/* SCTP kernel implementation * (C) Copyright IBM Corp. 2001, 2004 * Copyright (c) 1999-2000 Cisco, Inc. * Copyright (c) 1999-2001 Motorola, Inc. * Copyright (c) 2001-2002 Intel Corp. * Copyright (c) 2002 Nokia Corp. * * This is part of the SCTP Linux Kernel Implementation. * * These are the state functions for the state machine. * * This SCTP implementation is free software; * you can redistribute it and/or modify it under the terms of * the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * * This SCTP implementation is distributed in the hope that it * will be useful, but WITHOUT ANY WARRANTY; without even the implied * ************************ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with GNU CC; see the file COPYING. If not, see * . * * Please send any bug reports or fixes you make to the * email address(es): * lksctp developers * * Written or modified by: * La Monte H.P. Yarroll * Karl Knutson * Mathew Kotowsky * Sridhar Samudrala * Jon Grimm * Hui Huang * Dajiang Zhang * Daisy Chang * Ardelle Fan * Ryan Layer * Kevin Gao */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include static struct sctp_packet *sctp_abort_pkt_new(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, struct sctp_chunk *chunk, const void *payload, size_t paylen); static int sctp_eat_data(const struct sctp_association *asoc, struct sctp_chunk *chunk, sctp_cmd_seq_t *commands); static struct sctp_packet *sctp_ootb_pkt_new(struct net *net, const struct sctp_association *asoc, const struct sctp_chunk *chunk); static void sctp_send_stale_cookie_err(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const struct sctp_chunk *chunk, sctp_cmd_seq_t *commands, struct sctp_chunk *err_chunk); static sctp_disposition_t sctp_sf_do_5_2_6_stale(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); static sctp_disposition_t sctp_sf_shut_8_4_5(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); static sctp_disposition_t sctp_sf_tabort_8_4_8(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk); static sctp_disposition_t sctp_stop_t1_and_abort(struct net *net, sctp_cmd_seq_t *commands, __be16 error, int sk_err, const struct sctp_association *asoc, struct sctp_transport *transport); static sctp_disposition_t sctp_sf_abort_violation( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, void *arg, sctp_cmd_seq_t *commands, const __u8 *payload, const size_t paylen); static sctp_disposition_t sctp_sf_violation_chunklen( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); static sctp_disposition_t sctp_sf_violation_paramlen( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, void *ext, sctp_cmd_seq_t *commands); static sctp_disposition_t sctp_sf_violation_ctsn( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); static sctp_disposition_t sctp_sf_violation_chunk( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); static sctp_ierror_t sctp_sf_authenticate(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, struct sctp_chunk *chunk); static sctp_disposition_t __sctp_sf_do_9_1_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands); /* Small helper function that checks if the chunk length * is of the appropriate length. The 'required_length' argument * is set to be the size of a specific chunk we are testing. * Return Values: true = Valid length * false = Invalid length * */ static inline bool sctp_chunk_length_valid(struct sctp_chunk *chunk, __u16 required_length) { __u16 chunk_length = ntohs(chunk->chunk_hdr->length); /* Previously already marked? */ if (unlikely(chunk->pdiscard)) return false; if (unlikely(chunk_length < required_length)) return false; return true; } /********************************************************** * These are the state functions for handling chunk events. **********************************************************/ /* * Process the final SHUTDOWN COMPLETE. * * Section: 4 (C) (diagram), 9.2 * Upon reception of the SHUTDOWN COMPLETE chunk the endpoint will verify * that it is in SHUTDOWN-ACK-SENT state, if it is not the chunk should be * discarded. If the endpoint is in the SHUTDOWN-ACK-SENT state the endpoint * should stop the T2-shutdown timer and remove all knowledge of the * association (and thus the association enters the CLOSED state). * * Verification Tag: 8.5.1(C), sctpimpguide 2.41. * C) Rules for packet carrying SHUTDOWN COMPLETE: * ... * - The receiver of a SHUTDOWN COMPLETE shall accept the packet * if the Verification Tag field of the packet matches its own tag and * the T bit is not set * OR * it is set to its peer's tag and the T bit is set in the Chunk * Flags. * Otherwise, the receiver MUST silently discard the packet * and take no further action. An endpoint MUST ignore the * SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_4_C(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_ulpevent *ev; if (!sctp_vtag_verify_either(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* RFC 2960 6.10 Bundling * * An endpoint MUST NOT bundle INIT, INIT ACK or * SHUTDOWN COMPLETE with any other chunks. */ if (!chunk->singleton) return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands); /* Make sure that the SHUTDOWN_COMPLETE chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* RFC 2960 10.2 SCTP-to-ULP * * H) SHUTDOWN COMPLETE notification * * When SCTP completes the shutdown procedures (section 9.2) this * notification is passed to the upper layer. */ ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP, 0, 0, 0, NULL, GFP_ATOMIC); if (ev) sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); /* Upon reception of the SHUTDOWN COMPLETE chunk the endpoint * will verify that it is in SHUTDOWN-ACK-SENT state, if it is * not the chunk should be discarded. If the endpoint is in * the SHUTDOWN-ACK-SENT state the endpoint should stop the * T2-shutdown timer and remove all knowledge of the * association (and thus the association enters the CLOSED * state). */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_CLOSED)); SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL()); return SCTP_DISPOSITION_DELETE_TCB; } /* * Respond to a normal INIT chunk. * We are the side that is being asked for an association. * * Section: 5.1 Normal Establishment of an Association, B * B) "Z" shall respond immediately with an INIT ACK chunk. The * destination IP address of the INIT ACK MUST be set to the source * IP address of the INIT to which this INIT ACK is responding. In * the response, besides filling in other parameters, "Z" must set the * Verification Tag field to Tag_A, and also provide its own * Verification Tag (Tag_Z) in the Initiate Tag field. * * Verification Tag: Must be 0. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_1B_init(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_chunk *repl; struct sctp_association *new_asoc; struct sctp_chunk *err_chunk; struct sctp_packet *packet; sctp_unrecognized_param_t *unk_param; int len; /* 6.10 Bundling * An endpoint MUST NOT bundle INIT, INIT ACK or * SHUTDOWN COMPLETE with any other chunks. * * IG Section 2.11.2 * Furthermore, we require that the receiver of an INIT chunk MUST * enforce these rules by silently discarding an arriving packet * with an INIT chunk that is bundled with other chunks. */ if (!chunk->singleton) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* If the packet is an OOTB packet which is temporarily on the * control endpoint, respond with an ABORT. */ if (ep == sctp_sk(net->sctp.ctl_sock)->ep) { SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); } /* 3.1 A packet containing an INIT chunk MUST have a zero Verification * Tag. */ if (chunk->sctp_hdr->vtag != 0) return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); /* Make sure that the INIT chunk has a valid length. * Normally, this would cause an ABORT with a Protocol Violation * error, but since we don't have an association, we'll * just discard the packet. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_init_chunk_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* If the INIT is coming toward a closing socket, we'll send back * and ABORT. Essentially, this catches the race of INIT being * backloged to the socket at the same time as the user isses close(). * Since the socket and all its associations are going away, we * can treat this OOTB */ if (sctp_sstate(ep->base.sk, CLOSING)) return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); /* Verify the INIT chunk before processing it. */ err_chunk = NULL; if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type, (sctp_init_chunk_t *)chunk->chunk_hdr, chunk, &err_chunk)) { /* This chunk contains fatal error. It is to be discarded. * Send an ABORT, with causes if there is any. */ if (err_chunk) { packet = sctp_abort_pkt_new(net, ep, asoc, arg, (__u8 *)(err_chunk->chunk_hdr) + sizeof(sctp_chunkhdr_t), ntohs(err_chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t)); sctp_chunk_free(err_chunk); if (packet) { sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); return SCTP_DISPOSITION_CONSUME; } else { return SCTP_DISPOSITION_NOMEM; } } else { return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); } } /* Grab the INIT header. */ chunk->subh.init_hdr = (sctp_inithdr_t *)chunk->skb->data; /* Tag the variable length parameters. */ chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t)); new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC); if (!new_asoc) goto nomem; if (sctp_assoc_set_bind_addr_from_ep(new_asoc, sctp_scope(sctp_source(chunk)), GFP_ATOMIC) < 0) goto nomem_init; /* The call, sctp_process_init(), can fail on memory allocation. */ if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), (sctp_init_chunk_t *)chunk->chunk_hdr, GFP_ATOMIC)) goto nomem_init; /* B) "Z" shall respond immediately with an INIT ACK chunk. */ /* If there are errors need to be reported for unknown parameters, * make sure to reserve enough room in the INIT ACK for them. */ len = 0; if (err_chunk) len = ntohs(err_chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t); repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len); if (!repl) goto nomem_init; /* If there are errors need to be reported for unknown parameters, * include them in the outgoing INIT ACK as "Unrecognized parameter" * parameter. */ if (err_chunk) { /* Get the "Unrecognized parameter" parameter(s) out of the * ERROR chunk generated by sctp_verify_init(). Since the * error cause code for "unknown parameter" and the * "Unrecognized parameter" type is the same, we can * construct the parameters in INIT ACK by copying the * ERROR causes over. */ unk_param = (sctp_unrecognized_param_t *) ((__u8 *)(err_chunk->chunk_hdr) + sizeof(sctp_chunkhdr_t)); /* Replace the cause code with the "Unrecognized parameter" * parameter type. */ sctp_addto_chunk(repl, len, unk_param); sctp_chunk_free(err_chunk); } sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); /* * Note: After sending out INIT ACK with the State Cookie parameter, * "Z" MUST NOT allocate any resources, nor keep any states for the * new association. Otherwise, "Z" will be vulnerable to resource * attacks. */ sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL()); return SCTP_DISPOSITION_DELETE_TCB; nomem_init: sctp_association_free(new_asoc); nomem: if (err_chunk) sctp_chunk_free(err_chunk); return SCTP_DISPOSITION_NOMEM; } /* * Respond to a normal INIT ACK chunk. * We are the side that is initiating the association. * * Section: 5.1 Normal Establishment of an Association, C * C) Upon reception of the INIT ACK from "Z", "A" shall stop the T1-init * timer and leave COOKIE-WAIT state. "A" shall then send the State * Cookie received in the INIT ACK chunk in a COOKIE ECHO chunk, start * the T1-cookie timer, and enter the COOKIE-ECHOED state. * * Note: The COOKIE ECHO chunk can be bundled with any pending outbound * DATA chunks, but it MUST be the first chunk in the packet and * until the COOKIE ACK is returned the sender MUST NOT send any * other packets to the peer. * * Verification Tag: 3.3.3 * If the value of the Initiate Tag in a received INIT ACK chunk is * found to be 0, the receiver MUST treat it as an error and close the * association by transmitting an ABORT. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_1C_ack(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_init_chunk_t *initchunk; struct sctp_chunk *err_chunk; struct sctp_packet *packet; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* 6.10 Bundling * An endpoint MUST NOT bundle INIT, INIT ACK or * SHUTDOWN COMPLETE with any other chunks. */ if (!chunk->singleton) return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands); /* Make sure that the INIT-ACK chunk has a valid length */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_initack_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Grab the INIT header. */ chunk->subh.init_hdr = (sctp_inithdr_t *) chunk->skb->data; /* Verify the INIT chunk before processing it. */ err_chunk = NULL; if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type, (sctp_init_chunk_t *)chunk->chunk_hdr, chunk, &err_chunk)) { sctp_error_t error = SCTP_ERROR_NO_RESOURCE; /* This chunk contains fatal error. It is to be discarded. * Send an ABORT, with causes. If there are no causes, * then there wasn't enough memory. Just terminate * the association. */ if (err_chunk) { packet = sctp_abort_pkt_new(net, ep, asoc, arg, (__u8 *)(err_chunk->chunk_hdr) + sizeof(sctp_chunkhdr_t), ntohs(err_chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t)); sctp_chunk_free(err_chunk); if (packet) { sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); error = SCTP_ERROR_INV_PARAM; } } /* SCTP-AUTH, Section 6.3: * It should be noted that if the receiver wants to tear * down an association in an authenticated way only, the * handling of malformed packets should not result in * tearing down the association. * * This means that if we only want to abort associations * in an authenticated way (i.e AUTH+ABORT), then we * can't destroy this association just because the packet * was malformed. */ if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED, asoc, chunk->transport); } /* Tag the variable length parameters. Note that we never * convert the parameters in an INIT chunk. */ chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t)); initchunk = (sctp_init_chunk_t *) chunk->chunk_hdr; sctp_add_cmd_sf(commands, SCTP_CMD_PEER_INIT, SCTP_PEER_INIT(initchunk)); /* Reset init error count upon receipt of INIT-ACK. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL()); /* 5.1 C) "A" shall stop the T1-init timer and leave * COOKIE-WAIT state. "A" shall then ... start the T1-cookie * timer, and enter the COOKIE-ECHOED state. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_COOKIE_ECHOED)); /* SCTP-AUTH: genereate the assocition shared keys so that * we can potentially signe the COOKIE-ECHO. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_SHKEY, SCTP_NULL()); /* 5.1 C) "A" shall then send the State Cookie received in the * INIT ACK chunk in a COOKIE ECHO chunk, ... */ /* If there is any errors to report, send the ERROR chunk generated * for unknown parameters as well. */ sctp_add_cmd_sf(commands, SCTP_CMD_GEN_COOKIE_ECHO, SCTP_CHUNK(err_chunk)); return SCTP_DISPOSITION_CONSUME; } /* * Respond to a normal COOKIE ECHO chunk. * We are the side that is being asked for an association. * * Section: 5.1 Normal Establishment of an Association, D * D) Upon reception of the COOKIE ECHO chunk, Endpoint "Z" will reply * with a COOKIE ACK chunk after building a TCB and moving to * the ESTABLISHED state. A COOKIE ACK chunk may be bundled with * any pending DATA chunks (and/or SACK chunks), but the COOKIE ACK * chunk MUST be the first chunk in the packet. * * IMPLEMENTATION NOTE: An implementation may choose to send the * Communication Up notification to the SCTP user upon reception * of a valid COOKIE ECHO chunk. * * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules * D) Rules for packet carrying a COOKIE ECHO * * - When sending a COOKIE ECHO, the endpoint MUST use the value of the * Initial Tag received in the INIT ACK. * * - The receiver of a COOKIE ECHO follows the procedures in Section 5. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_association *new_asoc; sctp_init_chunk_t *peer_init; struct sctp_chunk *repl; struct sctp_ulpevent *ev, *ai_ev = NULL; int error = 0; struct sctp_chunk *err_chk_p; struct sock *sk; /* If the packet is an OOTB packet which is temporarily on the * control endpoint, respond with an ABORT. */ if (ep == sctp_sk(net->sctp.ctl_sock)->ep) { SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); } /* Make sure that the COOKIE_ECHO chunk has a valid length. * In this case, we check that we have enough for at least a * chunk header. More detailed verification is done * in sctp_unpack_cookie(). */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* If the endpoint is not listening or if the number of associations * on the TCP-style socket exceed the max backlog, respond with an * ABORT. */ sk = ep->base.sk; if (!sctp_sstate(sk, LISTENING) || (sctp_style(sk, TCP) && sk_acceptq_is_full(sk))) return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); /* "Decode" the chunk. We have no optional parameters so we * are in good shape. */ chunk->subh.cookie_hdr = (struct sctp_signed_cookie *)chunk->skb->data; if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t))) goto nomem; /* 5.1 D) Upon reception of the COOKIE ECHO chunk, Endpoint * "Z" will reply with a COOKIE ACK chunk after building a TCB * and moving to the ESTABLISHED state. */ new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error, &err_chk_p); /* FIXME: * If the re-build failed, what is the proper error path * from here? * * [We should abort the association. --piggy] */ if (!new_asoc) { /* FIXME: Several errors are possible. A bad cookie should * be silently discarded, but think about logging it too. */ switch (error) { case -SCTP_IERROR_NOMEM: goto nomem; case -SCTP_IERROR_STALE_COOKIE: sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands, err_chk_p); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); case -SCTP_IERROR_BAD_SIG: default: return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } } /* Delay state machine commands until later. * * Re-build the bind address for the association is done in * the sctp_unpack_cookie() already. */ /* This is a brand-new association, so these are not yet side * effects--it is safe to run them here. */ peer_init = &chunk->subh.cookie_hdr->c.peer_init[0]; if (!sctp_process_init(new_asoc, chunk, &chunk->subh.cookie_hdr->c.peer_addr, peer_init, GFP_ATOMIC)) goto nomem_init; /* SCTP-AUTH: Now that we've populate required fields in * sctp_process_init, set up the assocaition shared keys as * necessary so that we can potentially authenticate the ACK */ error = sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC); if (error) goto nomem_init; /* SCTP-AUTH: auth_chunk pointer is only set when the cookie-echo * is supposed to be authenticated and we have to do delayed * authentication. We've just recreated the association using * the information in the cookie and now it's much easier to * do the authentication. */ if (chunk->auth_chunk) { struct sctp_chunk auth; sctp_ierror_t ret; /* Make sure that we and the peer are AUTH capable */ if (!net->sctp.auth_enable || !new_asoc->peer.auth_capable) { sctp_association_free(new_asoc); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } /* set-up our fake chunk so that we can process it */ auth.skb = chunk->auth_chunk; auth.asoc = chunk->asoc; auth.sctp_hdr = chunk->sctp_hdr; auth.chunk_hdr = (sctp_chunkhdr_t *)skb_push(chunk->auth_chunk, sizeof(sctp_chunkhdr_t)); skb_pull(chunk->auth_chunk, sizeof(sctp_chunkhdr_t)); auth.transport = chunk->transport; ret = sctp_sf_authenticate(net, ep, new_asoc, type, &auth); if (ret != SCTP_IERROR_NO_ERROR) { sctp_association_free(new_asoc); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } } repl = sctp_make_cookie_ack(new_asoc, chunk); if (!repl) goto nomem_init; /* RFC 2960 5.1 Normal Establishment of an Association * * D) IMPLEMENTATION NOTE: An implementation may choose to * send the Communication Up notification to the SCTP user * upon reception of a valid COOKIE ECHO chunk. */ ev = sctp_ulpevent_make_assoc_change(new_asoc, 0, SCTP_COMM_UP, 0, new_asoc->c.sinit_num_ostreams, new_asoc->c.sinit_max_instreams, NULL, GFP_ATOMIC); if (!ev) goto nomem_ev; /* Sockets API Draft Section 5.3.1.6 * When a peer sends a Adaptation Layer Indication parameter , SCTP * delivers this notification to inform the application that of the * peers requested adaptation layer. */ if (new_asoc->peer.adaptation_ind) { ai_ev = sctp_ulpevent_make_adaptation_indication(new_asoc, GFP_ATOMIC); if (!ai_ev) goto nomem_aiev; } /* Add all the state machine commands now since we've created * everything. This way we don't introduce memory corruptions * during side-effect processing and correclty count established * associations. */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_ESTABLISHED)); SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB); SCTP_INC_STATS(net, SCTP_MIB_PASSIVEESTABS); sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL()); if (new_asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE)); /* This will send the COOKIE ACK */ sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); /* Queue the ASSOC_CHANGE event */ sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); /* Send up the Adaptation Layer Indication event */ if (ai_ev) sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ai_ev)); return SCTP_DISPOSITION_CONSUME; nomem_aiev: sctp_ulpevent_free(ev); nomem_ev: sctp_chunk_free(repl); nomem_init: sctp_association_free(new_asoc); nomem: return SCTP_DISPOSITION_NOMEM; } /* * Respond to a normal COOKIE ACK chunk. * We are the side that is asking for an association. * * RFC 2960 5.1 Normal Establishment of an Association * * E) Upon reception of the COOKIE ACK, endpoint "A" will move from the * COOKIE-ECHOED state to the ESTABLISHED state, stopping the T1-cookie * timer. It may also notify its ULP about the successful * establishment of the association with a Communication Up * notification (see Section 10). * * Verification Tag: * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_1E_ca(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_ulpevent *ev; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Verify that the chunk length for the COOKIE-ACK is OK. * If we don't do this, any bundled chunks may be junked. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Reset init error count upon receipt of COOKIE-ACK, * to avoid problems with the managemement of this * counter in stale cookie situations when a transition back * from the COOKIE-ECHOED state to the COOKIE-WAIT * state is performed. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL()); /* RFC 2960 5.1 Normal Establishment of an Association * * E) Upon reception of the COOKIE ACK, endpoint "A" will move * from the COOKIE-ECHOED state to the ESTABLISHED state, * stopping the T1-cookie timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_ESTABLISHED)); SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB); SCTP_INC_STATS(net, SCTP_MIB_ACTIVEESTABS); sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL()); if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE)); /* It may also notify its ULP about the successful * establishment of the association with a Communication Up * notification (see Section 10). */ ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP, 0, asoc->c.sinit_num_ostreams, asoc->c.sinit_max_instreams, NULL, GFP_ATOMIC); if (!ev) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); /* Sockets API Draft Section 5.3.1.6 * When a peer sends a Adaptation Layer Indication parameter , SCTP * delivers this notification to inform the application that of the * peers requested adaptation layer. */ if (asoc->peer.adaptation_ind) { ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC); if (!ev) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); } return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* Generate and sendout a heartbeat packet. */ static sctp_disposition_t sctp_sf_heartbeat(const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_transport *transport = (struct sctp_transport *) arg; struct sctp_chunk *reply; /* Send a heartbeat to our peer. */ reply = sctp_make_heartbeat(asoc, transport); if (!reply) return SCTP_DISPOSITION_NOMEM; /* Set rto_pending indicating that an RTT measurement * is started with this heartbeat chunk. */ sctp_add_cmd_sf(commands, SCTP_CMD_RTO_PENDING, SCTP_TRANSPORT(transport)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; } /* Generate a HEARTBEAT packet on the given transport. */ sctp_disposition_t sctp_sf_sendbeat_8_3(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_transport *transport = (struct sctp_transport *) arg; if (asoc->overall_error_count >= asoc->max_retrans) { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_DELETE_TCB; } /* Section 3.3.5. * The Sender-specific Heartbeat Info field should normally include * information about the sender's current time when this HEARTBEAT * chunk is sent and the destination transport address to which this * HEARTBEAT is sent (see Section 8.3). */ if (transport->param_flags & SPP_HB_ENABLE) { if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type, arg, commands)) return SCTP_DISPOSITION_NOMEM; /* Set transport error counter and association error counter * when sending heartbeat. */ sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT, SCTP_TRANSPORT(transport)); } sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_IDLE, SCTP_TRANSPORT(transport)); sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMER_UPDATE, SCTP_TRANSPORT(transport)); return SCTP_DISPOSITION_CONSUME; } /* resend asoc strreset_chunk. */ sctp_disposition_t sctp_sf_send_reconf(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_transport *transport = arg; if (asoc->overall_error_count >= asoc->max_retrans) { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_DELETE_TCB; } sctp_chunk_hold(asoc->strreset_chunk); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asoc->strreset_chunk)); sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport)); return SCTP_DISPOSITION_CONSUME; } /* * Process an heartbeat request. * * Section: 8.3 Path Heartbeat * The receiver of the HEARTBEAT should immediately respond with a * HEARTBEAT ACK that contains the Heartbeat Information field copied * from the received HEARTBEAT chunk. * * Verification Tag: 8.5 Verification Tag [Normal verification] * When receiving an SCTP packet, the endpoint MUST ensure that the * value in the Verification Tag field of the received SCTP packet * matches its own Tag. If the received Verification Tag value does not * match the receiver's own tag value, the receiver shall silently * discard the packet and shall not process it any further except for * those cases listed in Section 8.5.1 below. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_beat_8_3(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_paramhdr_t *param_hdr; struct sctp_chunk *chunk = arg; struct sctp_chunk *reply; size_t paylen = 0; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the HEARTBEAT chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_heartbeat_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* 8.3 The receiver of the HEARTBEAT should immediately * respond with a HEARTBEAT ACK that contains the Heartbeat * Information field copied from the received HEARTBEAT chunk. */ chunk->subh.hb_hdr = (sctp_heartbeathdr_t *) chunk->skb->data; param_hdr = (sctp_paramhdr_t *) chunk->subh.hb_hdr; paylen = ntohs(chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t); if (ntohs(param_hdr->length) > paylen) return sctp_sf_violation_paramlen(net, ep, asoc, type, arg, param_hdr, commands); if (!pskb_pull(chunk->skb, paylen)) goto nomem; reply = sctp_make_heartbeat_ack(asoc, chunk, param_hdr, paylen); if (!reply) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * Process the returning HEARTBEAT ACK. * * Section: 8.3 Path Heartbeat * Upon the receipt of the HEARTBEAT ACK, the sender of the HEARTBEAT * should clear the error counter of the destination transport * address to which the HEARTBEAT was sent, and mark the destination * transport address as active if it is not so marked. The endpoint may * optionally report to the upper layer when an inactive destination * address is marked as active due to the reception of the latest * HEARTBEAT ACK. The receiver of the HEARTBEAT ACK must also * clear the association overall error count as well (as defined * in section 8.1). * * The receiver of the HEARTBEAT ACK should also perform an RTT * measurement for that destination transport address using the time * value carried in the HEARTBEAT ACK chunk. * * Verification Tag: 8.5 Verification Tag [Normal verification] * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_backbeat_8_3(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; union sctp_addr from_addr; struct sctp_transport *link; sctp_sender_hb_info_t *hbinfo; unsigned long max_interval; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the HEARTBEAT-ACK chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t) + sizeof(sctp_sender_hb_info_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); hbinfo = (sctp_sender_hb_info_t *) chunk->skb->data; /* Make sure that the length of the parameter is what we expect */ if (ntohs(hbinfo->param_hdr.length) != sizeof(sctp_sender_hb_info_t)) { return SCTP_DISPOSITION_DISCARD; } from_addr = hbinfo->daddr; link = sctp_assoc_lookup_paddr(asoc, &from_addr); /* This should never happen, but lets log it if so. */ if (unlikely(!link)) { if (from_addr.sa.sa_family == AF_INET6) { net_warn_ratelimited("%s association %p could not find address %pI6\n", __func__, asoc, &from_addr.v6.sin6_addr); } else { net_warn_ratelimited("%s association %p could not find address %pI4\n", __func__, asoc, &from_addr.v4.sin_addr.s_addr); } return SCTP_DISPOSITION_DISCARD; } /* Validate the 64-bit random nonce. */ if (hbinfo->hb_nonce != link->hb_nonce) return SCTP_DISPOSITION_DISCARD; max_interval = link->hbinterval + link->rto; /* Check if the timestamp looks valid. */ if (time_after(hbinfo->sent_at, jiffies) || time_after(jiffies, hbinfo->sent_at + max_interval)) { pr_debug("%s: HEARTBEAT ACK with invalid timestamp received " "for transport:%p\n", __func__, link); return SCTP_DISPOSITION_DISCARD; } /* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of * the HEARTBEAT should clear the error counter of the * destination transport address to which the HEARTBEAT was * sent and mark the destination transport address as active if * it is not so marked. */ sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_ON, SCTP_TRANSPORT(link)); return SCTP_DISPOSITION_CONSUME; } /* Helper function to send out an abort for the restart * condition. */ static int sctp_sf_send_restart_abort(struct net *net, union sctp_addr *ssa, struct sctp_chunk *init, sctp_cmd_seq_t *commands) { int len; struct sctp_packet *pkt; union sctp_addr_param *addrparm; struct sctp_errhdr *errhdr; struct sctp_endpoint *ep; char buffer[sizeof(struct sctp_errhdr)+sizeof(union sctp_addr_param)]; struct sctp_af *af = sctp_get_af_specific(ssa->v4.sin_family); /* Build the error on the stack. We are way to malloc crazy * throughout the code today. */ errhdr = (struct sctp_errhdr *)buffer; addrparm = (union sctp_addr_param *)errhdr->variable; /* Copy into a parm format. */ len = af->to_addr_param(ssa, addrparm); len += sizeof(sctp_errhdr_t); errhdr->cause = SCTP_ERROR_RESTART; errhdr->length = htons(len); /* Assign to the control socket. */ ep = sctp_sk(net->sctp.ctl_sock)->ep; /* Association is NULL since this may be a restart attack and we * want to send back the attacker's vtag. */ pkt = sctp_abort_pkt_new(net, ep, NULL, init, errhdr, len); if (!pkt) goto out; sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(pkt)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); /* Discard the rest of the inbound packet. */ sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL()); out: /* Even if there is no memory, treat as a failure so * the packet will get dropped. */ return 0; } static bool list_has_sctp_addr(const struct list_head *list, union sctp_addr *ipaddr) { struct sctp_transport *addr; list_for_each_entry(addr, list, transports) { if (sctp_cmp_addr_exact(ipaddr, &addr->ipaddr)) return true; } return false; } /* A restart is occurring, check to make sure no new addresses * are being added as we may be under a takeover attack. */ static int sctp_sf_check_restart_addrs(const struct sctp_association *new_asoc, const struct sctp_association *asoc, struct sctp_chunk *init, sctp_cmd_seq_t *commands) { struct net *net = sock_net(new_asoc->base.sk); struct sctp_transport *new_addr; int ret = 1; /* Implementor's Guide - Section 5.2.2 * ... * Before responding the endpoint MUST check to see if the * unexpected INIT adds new addresses to the association. If new * addresses are added to the association, the endpoint MUST respond * with an ABORT.. */ /* Search through all current addresses and make sure * we aren't adding any new ones. */ list_for_each_entry(new_addr, &new_asoc->peer.transport_addr_list, transports) { if (!list_has_sctp_addr(&asoc->peer.transport_addr_list, &new_addr->ipaddr)) { sctp_sf_send_restart_abort(net, &new_addr->ipaddr, init, commands); ret = 0; break; } } /* Return success if all addresses were found. */ return ret; } /* Populate the verification/tie tags based on overlapping INIT * scenario. * * Note: Do not use in CLOSED or SHUTDOWN-ACK-SENT state. */ static void sctp_tietags_populate(struct sctp_association *new_asoc, const struct sctp_association *asoc) { switch (asoc->state) { /* 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State */ case SCTP_STATE_COOKIE_WAIT: new_asoc->c.my_vtag = asoc->c.my_vtag; new_asoc->c.my_ttag = asoc->c.my_vtag; new_asoc->c.peer_ttag = 0; break; case SCTP_STATE_COOKIE_ECHOED: new_asoc->c.my_vtag = asoc->c.my_vtag; new_asoc->c.my_ttag = asoc->c.my_vtag; new_asoc->c.peer_ttag = asoc->c.peer_vtag; break; /* 5.2.2 Unexpected INIT in States Other than CLOSED, COOKIE-ECHOED, * COOKIE-WAIT and SHUTDOWN-ACK-SENT */ default: new_asoc->c.my_ttag = asoc->c.my_vtag; new_asoc->c.peer_ttag = asoc->c.peer_vtag; break; } /* Other parameters for the endpoint SHOULD be copied from the * existing parameters of the association (e.g. number of * outbound streams) into the INIT ACK and cookie. */ new_asoc->rwnd = asoc->rwnd; new_asoc->c.sinit_num_ostreams = asoc->c.sinit_num_ostreams; new_asoc->c.sinit_max_instreams = asoc->c.sinit_max_instreams; new_asoc->c.initial_tsn = asoc->c.initial_tsn; } /* * Compare vtag/tietag values to determine unexpected COOKIE-ECHO * handling action. * * RFC 2960 5.2.4 Handle a COOKIE ECHO when a TCB exists. * * Returns value representing action to be taken. These action values * correspond to Action/Description values in RFC 2960, Table 2. */ static char sctp_tietags_compare(struct sctp_association *new_asoc, const struct sctp_association *asoc) { /* In this case, the peer may have restarted. */ if ((asoc->c.my_vtag != new_asoc->c.my_vtag) && (asoc->c.peer_vtag != new_asoc->c.peer_vtag) && (asoc->c.my_vtag == new_asoc->c.my_ttag) && (asoc->c.peer_vtag == new_asoc->c.peer_ttag)) return 'A'; /* Collision case B. */ if ((asoc->c.my_vtag == new_asoc->c.my_vtag) && ((asoc->c.peer_vtag != new_asoc->c.peer_vtag) || (0 == asoc->c.peer_vtag))) { return 'B'; } /* Collision case D. */ if ((asoc->c.my_vtag == new_asoc->c.my_vtag) && (asoc->c.peer_vtag == new_asoc->c.peer_vtag)) return 'D'; /* Collision case C. */ if ((asoc->c.my_vtag != new_asoc->c.my_vtag) && (asoc->c.peer_vtag == new_asoc->c.peer_vtag) && (0 == new_asoc->c.my_ttag) && (0 == new_asoc->c.peer_ttag)) return 'C'; /* No match to any of the special cases; discard this packet. */ return 'E'; } /* Common helper routine for both duplicate and simulataneous INIT * chunk handling. */ static sctp_disposition_t sctp_sf_do_unexpected_init( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_disposition_t retval; struct sctp_chunk *chunk = arg; struct sctp_chunk *repl; struct sctp_association *new_asoc; struct sctp_chunk *err_chunk; struct sctp_packet *packet; sctp_unrecognized_param_t *unk_param; int len; /* 6.10 Bundling * An endpoint MUST NOT bundle INIT, INIT ACK or * SHUTDOWN COMPLETE with any other chunks. * * IG Section 2.11.2 * Furthermore, we require that the receiver of an INIT chunk MUST * enforce these rules by silently discarding an arriving packet * with an INIT chunk that is bundled with other chunks. */ if (!chunk->singleton) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* 3.1 A packet containing an INIT chunk MUST have a zero Verification * Tag. */ if (chunk->sctp_hdr->vtag != 0) return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); /* Make sure that the INIT chunk has a valid length. * In this case, we generate a protocol violation since we have * an association established. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_init_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Grab the INIT header. */ chunk->subh.init_hdr = (sctp_inithdr_t *) chunk->skb->data; /* Tag the variable length parameters. */ chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t)); /* Verify the INIT chunk before processing it. */ err_chunk = NULL; if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type, (sctp_init_chunk_t *)chunk->chunk_hdr, chunk, &err_chunk)) { /* This chunk contains fatal error. It is to be discarded. * Send an ABORT, with causes if there is any. */ if (err_chunk) { packet = sctp_abort_pkt_new(net, ep, asoc, arg, (__u8 *)(err_chunk->chunk_hdr) + sizeof(sctp_chunkhdr_t), ntohs(err_chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t)); if (packet) { sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); retval = SCTP_DISPOSITION_CONSUME; } else { retval = SCTP_DISPOSITION_NOMEM; } goto cleanup; } else { return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); } } /* * Other parameters for the endpoint SHOULD be copied from the * existing parameters of the association (e.g. number of * outbound streams) into the INIT ACK and cookie. * FIXME: We are copying parameters from the endpoint not the * association. */ new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC); if (!new_asoc) goto nomem; if (sctp_assoc_set_bind_addr_from_ep(new_asoc, sctp_scope(sctp_source(chunk)), GFP_ATOMIC) < 0) goto nomem; /* In the outbound INIT ACK the endpoint MUST copy its current * Verification Tag and Peers Verification tag into a reserved * place (local tie-tag and per tie-tag) within the state cookie. */ if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), (sctp_init_chunk_t *)chunk->chunk_hdr, GFP_ATOMIC)) goto nomem; /* Make sure no new addresses are being added during the * restart. Do not do this check for COOKIE-WAIT state, * since there are no peer addresses to check against. * Upon return an ABORT will have been sent if needed. */ if (!sctp_state(asoc, COOKIE_WAIT)) { if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk, commands)) { retval = SCTP_DISPOSITION_CONSUME; goto nomem_retval; } } sctp_tietags_populate(new_asoc, asoc); /* B) "Z" shall respond immediately with an INIT ACK chunk. */ /* If there are errors need to be reported for unknown parameters, * make sure to reserve enough room in the INIT ACK for them. */ len = 0; if (err_chunk) { len = ntohs(err_chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t); } repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len); if (!repl) goto nomem; /* If there are errors need to be reported for unknown parameters, * include them in the outgoing INIT ACK as "Unrecognized parameter" * parameter. */ if (err_chunk) { /* Get the "Unrecognized parameter" parameter(s) out of the * ERROR chunk generated by sctp_verify_init(). Since the * error cause code for "unknown parameter" and the * "Unrecognized parameter" type is the same, we can * construct the parameters in INIT ACK by copying the * ERROR causes over. */ unk_param = (sctp_unrecognized_param_t *) ((__u8 *)(err_chunk->chunk_hdr) + sizeof(sctp_chunkhdr_t)); /* Replace the cause code with the "Unrecognized parameter" * parameter type. */ sctp_addto_chunk(repl, len, unk_param); } sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); /* * Note: After sending out INIT ACK with the State Cookie parameter, * "Z" MUST NOT allocate any resources for this new association. * Otherwise, "Z" will be vulnerable to resource attacks. */ sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL()); retval = SCTP_DISPOSITION_CONSUME; return retval; nomem: retval = SCTP_DISPOSITION_NOMEM; nomem_retval: if (new_asoc) sctp_association_free(new_asoc); cleanup: if (err_chunk) sctp_chunk_free(err_chunk); return retval; } /* * Handle simultaneous INIT. * This means we started an INIT and then we got an INIT request from * our peer. * * Section: 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State (Item B) * This usually indicates an initialization collision, i.e., each * endpoint is attempting, at about the same time, to establish an * association with the other endpoint. * * Upon receipt of an INIT in the COOKIE-WAIT or COOKIE-ECHOED state, an * endpoint MUST respond with an INIT ACK using the same parameters it * sent in its original INIT chunk (including its Verification Tag, * unchanged). These original parameters are combined with those from the * newly received INIT chunk. The endpoint shall also generate a State * Cookie with the INIT ACK. The endpoint uses the parameters sent in its * INIT to calculate the State Cookie. * * After that, the endpoint MUST NOT change its state, the T1-init * timer shall be left running and the corresponding TCB MUST NOT be * destroyed. The normal procedures for handling State Cookies when * a TCB exists will resolve the duplicate INITs to a single association. * * For an endpoint that is in the COOKIE-ECHOED state it MUST populate * its Tie-Tags with the Tag information of itself and its peer (see * section 5.2.2 for a description of the Tie-Tags). * * Verification Tag: Not explicit, but an INIT can not have a valid * verification tag, so we skip the check. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_2_1_siminit(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* Call helper to do the real work for both simulataneous and * duplicate INIT chunk handling. */ return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands); } /* * Handle duplicated INIT messages. These are usually delayed * restransmissions. * * Section: 5.2.2 Unexpected INIT in States Other than CLOSED, * COOKIE-ECHOED and COOKIE-WAIT * * Unless otherwise stated, upon reception of an unexpected INIT for * this association, the endpoint shall generate an INIT ACK with a * State Cookie. In the outbound INIT ACK the endpoint MUST copy its * current Verification Tag and peer's Verification Tag into a reserved * place within the state cookie. We shall refer to these locations as * the Peer's-Tie-Tag and the Local-Tie-Tag. The outbound SCTP packet * containing this INIT ACK MUST carry a Verification Tag value equal to * the Initiation Tag found in the unexpected INIT. And the INIT ACK * MUST contain a new Initiation Tag (randomly generated see Section * 5.3.1). Other parameters for the endpoint SHOULD be copied from the * existing parameters of the association (e.g. number of outbound * streams) into the INIT ACK and cookie. * * After sending out the INIT ACK, the endpoint shall take no further * actions, i.e., the existing association, including its current state, * and the corresponding TCB MUST NOT be changed. * * Note: Only when a TCB exists and the association is not in a COOKIE- * WAIT state are the Tie-Tags populated. For a normal association INIT * (i.e. the endpoint is in a COOKIE-WAIT state), the Tie-Tags MUST be * set to 0 (indicating that no previous TCB existed). The INIT ACK and * State Cookie are populated as specified in section 5.2.1. * * Verification Tag: Not specified, but an INIT has no way of knowing * what the verification tag could be, so we ignore it. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_2_2_dupinit(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* Call helper to do the real work for both simulataneous and * duplicate INIT chunk handling. */ return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands); } /* * Unexpected INIT-ACK handler. * * Section 5.2.3 * If an INIT ACK received by an endpoint in any state other than the * COOKIE-WAIT state, the endpoint should discard the INIT ACK chunk. * An unexpected INIT ACK usually indicates the processing of an old or * duplicated INIT chunk. */ sctp_disposition_t sctp_sf_do_5_2_3_initack(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* Per the above section, we'll discard the chunk if we have an * endpoint. If this is an OOTB INIT-ACK, treat it as such. */ if (ep == sctp_sk(net->sctp.ctl_sock)->ep) return sctp_sf_ootb(net, ep, asoc, type, arg, commands); else return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands); } /* Unexpected COOKIE-ECHO handler for peer restart (Table 2, action 'A') * * Section 5.2.4 * A) In this case, the peer may have restarted. */ static sctp_disposition_t sctp_sf_do_dupcook_a(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, struct sctp_chunk *chunk, sctp_cmd_seq_t *commands, struct sctp_association *new_asoc) { sctp_init_chunk_t *peer_init; struct sctp_ulpevent *ev; struct sctp_chunk *repl; struct sctp_chunk *err; sctp_disposition_t disposition; /* new_asoc is a brand-new association, so these are not yet * side effects--it is safe to run them here. */ peer_init = &chunk->subh.cookie_hdr->c.peer_init[0]; if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init, GFP_ATOMIC)) goto nomem; /* Make sure no new addresses are being added during the * restart. Though this is a pretty complicated attack * since you'd have to get inside the cookie. */ if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk, commands)) { return SCTP_DISPOSITION_CONSUME; } /* If the endpoint is in the SHUTDOWN-ACK-SENT state and recognizes * the peer has restarted (Action A), it MUST NOT setup a new * association but instead resend the SHUTDOWN ACK and send an ERROR * chunk with a "Cookie Received while Shutting Down" error cause to * its peer. */ if (sctp_state(asoc, SHUTDOWN_ACK_SENT)) { disposition = sctp_sf_do_9_2_reshutack(net, ep, asoc, SCTP_ST_CHUNK(chunk->chunk_hdr->type), chunk, commands); if (SCTP_DISPOSITION_NOMEM == disposition) goto nomem; err = sctp_make_op_error(asoc, chunk, SCTP_ERROR_COOKIE_IN_SHUTDOWN, NULL, 0, 0); if (err) sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(err)); return SCTP_DISPOSITION_CONSUME; } /* For now, stop pending T3-rtx and SACK timers, fail any unsent/unacked * data. Consider the optional choice of resending of this data. */ sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_SACK)); sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_OUTQUEUE, SCTP_NULL()); /* Stop pending T4-rto timer, teardown ASCONF queue, ASCONF-ACK queue * and ASCONF-ACK cache. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO)); sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_ASCONF_QUEUE, SCTP_NULL()); repl = sctp_make_cookie_ack(new_asoc, chunk); if (!repl) goto nomem; /* Report association restart to upper layer. */ ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_RESTART, 0, new_asoc->c.sinit_num_ostreams, new_asoc->c.sinit_max_instreams, NULL, GFP_ATOMIC); if (!ev) goto nomem_ev; /* Update the content of current association. */ sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc)); sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); if (sctp_state(asoc, SHUTDOWN_PENDING) && (sctp_sstate(asoc->base.sk, CLOSING) || sock_flag(asoc->base.sk, SOCK_DEAD))) { /* if were currently in SHUTDOWN_PENDING, but the socket * has been closed by user, don't transition to ESTABLISHED. * Instead trigger SHUTDOWN bundled with COOKIE_ACK. */ sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); return sctp_sf_do_9_2_start_shutdown(net, ep, asoc, SCTP_ST_CHUNK(0), NULL, commands); } else { sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_ESTABLISHED)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); } return SCTP_DISPOSITION_CONSUME; nomem_ev: sctp_chunk_free(repl); nomem: return SCTP_DISPOSITION_NOMEM; } /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'B') * * Section 5.2.4 * B) In this case, both sides may be attempting to start an association * at about the same time but the peer endpoint started its INIT * after responding to the local endpoint's INIT */ /* This case represents an initialization collision. */ static sctp_disposition_t sctp_sf_do_dupcook_b(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, struct sctp_chunk *chunk, sctp_cmd_seq_t *commands, struct sctp_association *new_asoc) { sctp_init_chunk_t *peer_init; struct sctp_chunk *repl; /* new_asoc is a brand-new association, so these are not yet * side effects--it is safe to run them here. */ peer_init = &chunk->subh.cookie_hdr->c.peer_init[0]; if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init, GFP_ATOMIC)) goto nomem; /* Update the content of current association. */ sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_ESTABLISHED)); SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB); sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL()); repl = sctp_make_cookie_ack(new_asoc, chunk); if (!repl) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); /* RFC 2960 5.1 Normal Establishment of an Association * * D) IMPLEMENTATION NOTE: An implementation may choose to * send the Communication Up notification to the SCTP user * upon reception of a valid COOKIE ECHO chunk. * * Sadly, this needs to be implemented as a side-effect, because * we are not guaranteed to have set the association id of the real * association and so these notifications need to be delayed until * the association id is allocated. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_CHANGE, SCTP_U8(SCTP_COMM_UP)); /* Sockets API Draft Section 5.3.1.6 * When a peer sends a Adaptation Layer Indication parameter , SCTP * delivers this notification to inform the application that of the * peers requested adaptation layer. * * This also needs to be done as a side effect for the same reason as * above. */ if (asoc->peer.adaptation_ind) sctp_add_cmd_sf(commands, SCTP_CMD_ADAPTATION_IND, SCTP_NULL()); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'C') * * Section 5.2.4 * C) In this case, the local endpoint's cookie has arrived late. * Before it arrived, the local endpoint sent an INIT and received an * INIT-ACK and finally sent a COOKIE ECHO with the peer's same tag * but a new tag of its own. */ /* This case represents an initialization collision. */ static sctp_disposition_t sctp_sf_do_dupcook_c(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, struct sctp_chunk *chunk, sctp_cmd_seq_t *commands, struct sctp_association *new_asoc) { /* The cookie should be silently discarded. * The endpoint SHOULD NOT change states and should leave * any timers running. */ return SCTP_DISPOSITION_DISCARD; } /* Unexpected COOKIE-ECHO handler lost chunk (Table 2, action 'D') * * Section 5.2.4 * * D) When both local and remote tags match the endpoint should always * enter the ESTABLISHED state, if it has not already done so. */ /* This case represents an initialization collision. */ static sctp_disposition_t sctp_sf_do_dupcook_d(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, struct sctp_chunk *chunk, sctp_cmd_seq_t *commands, struct sctp_association *new_asoc) { struct sctp_ulpevent *ev = NULL, *ai_ev = NULL; struct sctp_chunk *repl; /* Clarification from Implementor's Guide: * D) When both local and remote tags match the endpoint should * enter the ESTABLISHED state, if it is in the COOKIE-ECHOED state. * It should stop any cookie timer that may be running and send * a COOKIE ACK. */ /* Don't accidentally move back into established state. */ if (asoc->state < SCTP_STATE_ESTABLISHED) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_ESTABLISHED)); SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB); sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL()); /* RFC 2960 5.1 Normal Establishment of an Association * * D) IMPLEMENTATION NOTE: An implementation may choose * to send the Communication Up notification to the * SCTP user upon reception of a valid COOKIE * ECHO chunk. */ ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP, 0, asoc->c.sinit_num_ostreams, asoc->c.sinit_max_instreams, NULL, GFP_ATOMIC); if (!ev) goto nomem; /* Sockets API Draft Section 5.3.1.6 * When a peer sends a Adaptation Layer Indication parameter, * SCTP delivers this notification to inform the application * that of the peers requested adaptation layer. */ if (asoc->peer.adaptation_ind) { ai_ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC); if (!ai_ev) goto nomem; } } repl = sctp_make_cookie_ack(new_asoc, chunk); if (!repl) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); if (ev) sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); if (ai_ev) sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ai_ev)); return SCTP_DISPOSITION_CONSUME; nomem: if (ai_ev) sctp_ulpevent_free(ai_ev); if (ev) sctp_ulpevent_free(ev); return SCTP_DISPOSITION_NOMEM; } /* * Handle a duplicate COOKIE-ECHO. This usually means a cookie-carrying * chunk was retransmitted and then delayed in the network. * * Section: 5.2.4 Handle a COOKIE ECHO when a TCB exists * * Verification Tag: None. Do cookie validation. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_5_2_4_dupcook(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_disposition_t retval; struct sctp_chunk *chunk = arg; struct sctp_association *new_asoc; int error = 0; char action; struct sctp_chunk *err_chk_p; /* Make sure that the chunk has a valid length from the protocol * perspective. In this case check to make sure we have at least * enough for the chunk header. Cookie length verification is * done later. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* "Decode" the chunk. We have no optional parameters so we * are in good shape. */ chunk->subh.cookie_hdr = (struct sctp_signed_cookie *)chunk->skb->data; if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t))) goto nomem; /* In RFC 2960 5.2.4 3, if both Verification Tags in the State Cookie * of a duplicate COOKIE ECHO match the Verification Tags of the * current association, consider the State Cookie valid even if * the lifespan is exceeded. */ new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error, &err_chk_p); /* FIXME: * If the re-build failed, what is the proper error path * from here? * * [We should abort the association. --piggy] */ if (!new_asoc) { /* FIXME: Several errors are possible. A bad cookie should * be silently discarded, but think about logging it too. */ switch (error) { case -SCTP_IERROR_NOMEM: goto nomem; case -SCTP_IERROR_STALE_COOKIE: sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands, err_chk_p); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); case -SCTP_IERROR_BAD_SIG: default: return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } } /* Compare the tie_tag in cookie with the verification tag of * current association. */ action = sctp_tietags_compare(new_asoc, asoc); switch (action) { case 'A': /* Association restart. */ retval = sctp_sf_do_dupcook_a(net, ep, asoc, chunk, commands, new_asoc); break; case 'B': /* Collision case B. */ retval = sctp_sf_do_dupcook_b(net, ep, asoc, chunk, commands, new_asoc); break; case 'C': /* Collision case C. */ retval = sctp_sf_do_dupcook_c(net, ep, asoc, chunk, commands, new_asoc); break; case 'D': /* Collision case D. */ retval = sctp_sf_do_dupcook_d(net, ep, asoc, chunk, commands, new_asoc); break; default: /* Discard packet for all others. */ retval = sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); break; } /* Delete the tempory new association. */ sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC, SCTP_ASOC(new_asoc)); sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL()); /* Restore association pointer to provide SCTP command interpeter * with a valid context in case it needs to manipulate * the queues */ sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC, SCTP_ASOC((struct sctp_association *)asoc)); return retval; nomem: return SCTP_DISPOSITION_NOMEM; } /* * Process an ABORT. (SHUTDOWN-PENDING state) * * See sctp_sf_do_9_1_abort(). */ sctp_disposition_t sctp_sf_shutdown_pending_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; if (!sctp_vtag_verify_either(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the ABORT chunk has a valid length. * Since this is an ABORT chunk, we have to discard it * because of the following text: * RFC 2960, Section 3.3.7 * If an endpoint receives an ABORT with a format error or for an * association that doesn't exist, it MUST silently discard it. * Because the length is "invalid", we can't really discard just * as we do not know its true length. So, to be safe, discard the * packet. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* ADD-IP: Special case for ABORT chunks * F4) One special consideration is that ABORT Chunks arriving * destined to the IP address being deleted MUST be * ignored (see Section 5.3.1 for further details). */ if (SCTP_ADDR_DEL == sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest)) return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands); return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands); } /* * Process an ABORT. (SHUTDOWN-SENT state) * * See sctp_sf_do_9_1_abort(). */ sctp_disposition_t sctp_sf_shutdown_sent_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; if (!sctp_vtag_verify_either(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the ABORT chunk has a valid length. * Since this is an ABORT chunk, we have to discard it * because of the following text: * RFC 2960, Section 3.3.7 * If an endpoint receives an ABORT with a format error or for an * association that doesn't exist, it MUST silently discard it. * Because the length is "invalid", we can't really discard just * as we do not know its true length. So, to be safe, discard the * packet. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* ADD-IP: Special case for ABORT chunks * F4) One special consideration is that ABORT Chunks arriving * destined to the IP address being deleted MUST be * ignored (see Section 5.3.1 for further details). */ if (SCTP_ADDR_DEL == sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest)) return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands); /* Stop the T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); /* Stop the T5-shutdown guard timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands); } /* * Process an ABORT. (SHUTDOWN-ACK-SENT state) * * See sctp_sf_do_9_1_abort(). */ sctp_disposition_t sctp_sf_shutdown_ack_sent_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* The same T2 timer, so we should be able to use * common function with the SHUTDOWN-SENT state. */ return sctp_sf_shutdown_sent_abort(net, ep, asoc, type, arg, commands); } /* * Handle an Error received in COOKIE_ECHOED state. * * Only handle the error type of stale COOKIE Error, the other errors will * be ignored. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_cookie_echoed_err(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_errhdr_t *err; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the ERROR chunk has a valid length. * The parameter walking depends on this as well. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_operr_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Process the error here */ /* FUTURE FIXME: When PR-SCTP related and other optional * parms are emitted, this will have to change to handle multiple * errors. */ sctp_walk_errors(err, chunk->chunk_hdr) { if (SCTP_ERROR_STALE_COOKIE == err->cause) return sctp_sf_do_5_2_6_stale(net, ep, asoc, type, arg, commands); } /* It is possible to have malformed error causes, and that * will cause us to end the walk early. However, since * we are discarding the packet, there should be no adverse * affects. */ return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } /* * Handle a Stale COOKIE Error * * Section: 5.2.6 Handle Stale COOKIE Error * If the association is in the COOKIE-ECHOED state, the endpoint may elect * one of the following three alternatives. * ... * 3) Send a new INIT chunk to the endpoint, adding a Cookie * Preservative parameter requesting an extension to the lifetime of * the State Cookie. When calculating the time extension, an * implementation SHOULD use the RTT information measured based on the * previous COOKIE ECHO / ERROR exchange, and should add no more * than 1 second beyond the measured RTT, due to long State Cookie * lifetimes making the endpoint more subject to a replay attack. * * Verification Tag: Not explicit, but safe to ignore. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ static sctp_disposition_t sctp_sf_do_5_2_6_stale(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; u32 stale; sctp_cookie_preserve_param_t bht; sctp_errhdr_t *err; struct sctp_chunk *reply; struct sctp_bind_addr *bp; int attempts = asoc->init_err_counter + 1; if (attempts > asoc->max_init_attempts) { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED, SCTP_PERR(SCTP_ERROR_STALE_COOKIE)); return SCTP_DISPOSITION_DELETE_TCB; } err = (sctp_errhdr_t *)(chunk->skb->data); /* When calculating the time extension, an implementation * SHOULD use the RTT information measured based on the * previous COOKIE ECHO / ERROR exchange, and should add no * more than 1 second beyond the measured RTT, due to long * State Cookie lifetimes making the endpoint more subject to * a replay attack. * Measure of Staleness's unit is usec. (1/1000000 sec) * Suggested Cookie Life-span Increment's unit is msec. * (1/1000 sec) * In general, if you use the suggested cookie life, the value * found in the field of measure of staleness should be doubled * to give ample time to retransmit the new cookie and thus * yield a higher probability of success on the reattempt. */ stale = ntohl(*(__be32 *)((u8 *)err + sizeof(sctp_errhdr_t))); stale = (stale * 2) / 1000; bht.param_hdr.type = SCTP_PARAM_COOKIE_PRESERVATIVE; bht.param_hdr.length = htons(sizeof(bht)); bht.lifespan_increment = htonl(stale); /* Build that new INIT chunk. */ bp = (struct sctp_bind_addr *) &asoc->base.bind_addr; reply = sctp_make_init(asoc, bp, GFP_ATOMIC, sizeof(bht)); if (!reply) goto nomem; sctp_addto_chunk(reply, sizeof(bht), &bht); /* Clear peer's init_tag cached in assoc as we are sending a new INIT */ sctp_add_cmd_sf(commands, SCTP_CMD_CLEAR_INIT_TAG, SCTP_NULL()); /* Stop pending T3-rtx and heartbeat timers */ sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL()); /* Delete non-primary peer ip addresses since we are transitioning * back to the COOKIE-WAIT state */ sctp_add_cmd_sf(commands, SCTP_CMD_DEL_NON_PRIMARY, SCTP_NULL()); /* If we've sent any data bundled with COOKIE-ECHO we will need to * resend */ sctp_add_cmd_sf(commands, SCTP_CMD_T1_RETRAN, SCTP_TRANSPORT(asoc->peer.primary_path)); /* Cast away the const modifier, as we want to just * rerun it through as a sideffect. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_INC, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_COOKIE_WAIT)); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * Process an ABORT. * * Section: 9.1 * After checking the Verification Tag, the receiving endpoint shall * remove the association from its record, and shall report the * termination to its upper layer. * * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules * B) Rules for packet carrying ABORT: * * - The endpoint shall always fill in the Verification Tag field of the * outbound packet with the destination endpoint's tag value if it * is known. * * - If the ABORT is sent in response to an OOTB packet, the endpoint * MUST follow the procedure described in Section 8.4. * * - The receiver MUST accept the packet if the Verification Tag * matches either its own tag, OR the tag of its peer. Otherwise, the * receiver MUST silently discard the packet and take no further * action. * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_9_1_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; if (!sctp_vtag_verify_either(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the ABORT chunk has a valid length. * Since this is an ABORT chunk, we have to discard it * because of the following text: * RFC 2960, Section 3.3.7 * If an endpoint receives an ABORT with a format error or for an * association that doesn't exist, it MUST silently discard it. * Because the length is "invalid", we can't really discard just * as we do not know its true length. So, to be safe, discard the * packet. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* ADD-IP: Special case for ABORT chunks * F4) One special consideration is that ABORT Chunks arriving * destined to the IP address being deleted MUST be * ignored (see Section 5.3.1 for further details). */ if (SCTP_ADDR_DEL == sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest)) return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands); return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands); } static sctp_disposition_t __sctp_sf_do_9_1_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; unsigned int len; __be16 error = SCTP_ERROR_NO_ERROR; /* See if we have an error cause code in the chunk. */ len = ntohs(chunk->chunk_hdr->length); if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr)) { sctp_errhdr_t *err; sctp_walk_errors(err, chunk->chunk_hdr); if ((void *)err != (void *)chunk->chunk_end) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); error = ((sctp_errhdr_t *)chunk->skb->data)->cause; } sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNRESET)); /* ASSOC_FAILED will DELETE_TCB. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(error)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_ABORT; } /* * Process an ABORT. (COOKIE-WAIT state) * * See sctp_sf_do_9_1_abort() above. */ sctp_disposition_t sctp_sf_cookie_wait_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; unsigned int len; __be16 error = SCTP_ERROR_NO_ERROR; if (!sctp_vtag_verify_either(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the ABORT chunk has a valid length. * Since this is an ABORT chunk, we have to discard it * because of the following text: * RFC 2960, Section 3.3.7 * If an endpoint receives an ABORT with a format error or for an * association that doesn't exist, it MUST silently discard it. * Because the length is "invalid", we can't really discard just * as we do not know its true length. So, to be safe, discard the * packet. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* See if we have an error cause code in the chunk. */ len = ntohs(chunk->chunk_hdr->length); if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr)) error = ((sctp_errhdr_t *)chunk->skb->data)->cause; return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED, asoc, chunk->transport); } /* * Process an incoming ICMP as an ABORT. (COOKIE-WAIT state) */ sctp_disposition_t sctp_sf_cookie_wait_icmp_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { return sctp_stop_t1_and_abort(net, commands, SCTP_ERROR_NO_ERROR, ENOPROTOOPT, asoc, (struct sctp_transport *)arg); } /* * Process an ABORT. (COOKIE-ECHOED state) */ sctp_disposition_t sctp_sf_cookie_echoed_abort(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* There is a single T1 timer, so we should be able to use * common function with the COOKIE-WAIT state. */ return sctp_sf_cookie_wait_abort(net, ep, asoc, type, arg, commands); } /* * Stop T1 timer and abort association with "INIT failed". * * This is common code called by several sctp_sf_*_abort() functions above. */ static sctp_disposition_t sctp_stop_t1_and_abort(struct net *net, sctp_cmd_seq_t *commands, __be16 error, int sk_err, const struct sctp_association *asoc, struct sctp_transport *transport) { pr_debug("%s: ABORT received (INIT)\n", __func__); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_CLOSED)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(sk_err)); /* CMD_INIT_FAILED will DELETE_TCB. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED, SCTP_PERR(error)); return SCTP_DISPOSITION_ABORT; } /* * sctp_sf_do_9_2_shut * * Section: 9.2 * Upon the reception of the SHUTDOWN, the peer endpoint shall * - enter the SHUTDOWN-RECEIVED state, * * - stop accepting new data from its SCTP user * * - verify, by checking the Cumulative TSN Ack field of the chunk, * that all its outstanding DATA chunks have been received by the * SHUTDOWN sender. * * Once an endpoint as reached the SHUTDOWN-RECEIVED state it MUST NOT * send a SHUTDOWN in response to a ULP request. And should discard * subsequent SHUTDOWN chunks. * * If there are still outstanding DATA chunks left, the SHUTDOWN * receiver shall continue to follow normal data transmission * procedures defined in Section 6 until all outstanding DATA chunks * are acknowledged; however, the SHUTDOWN receiver MUST NOT accept * new data from its SCTP user. * * Verification Tag: 8.5 Verification Tag [Normal verification] * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_9_2_shutdown(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_shutdownhdr_t *sdh; sctp_disposition_t disposition; struct sctp_ulpevent *ev; __u32 ctsn; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the SHUTDOWN chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Convert the elaborate header. */ sdh = (sctp_shutdownhdr_t *)chunk->skb->data; skb_pull(chunk->skb, sizeof(sctp_shutdownhdr_t)); chunk->subh.shutdown_hdr = sdh; ctsn = ntohl(sdh->cum_tsn_ack); if (TSN_lt(ctsn, asoc->ctsn_ack_point)) { pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn, asoc->ctsn_ack_point); return SCTP_DISPOSITION_DISCARD; } /* If Cumulative TSN Ack beyond the max tsn currently * send, terminating the association and respond to the * sender with an ABORT. */ if (!TSN_lt(ctsn, asoc->next_tsn)) return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands); /* API 5.3.1.5 SCTP_SHUTDOWN_EVENT * When a peer sends a SHUTDOWN, SCTP delivers this notification to * inform the application that it should cease sending data. */ ev = sctp_ulpevent_make_shutdown_event(asoc, 0, GFP_ATOMIC); if (!ev) { disposition = SCTP_DISPOSITION_NOMEM; goto out; } sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); /* Upon the reception of the SHUTDOWN, the peer endpoint shall * - enter the SHUTDOWN-RECEIVED state, * - stop accepting new data from its SCTP user * * [This is implicit in the new state.] */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_SHUTDOWN_RECEIVED)); disposition = SCTP_DISPOSITION_CONSUME; if (sctp_outq_is_empty(&asoc->outqueue)) { disposition = sctp_sf_do_9_2_shutdown_ack(net, ep, asoc, type, arg, commands); } if (SCTP_DISPOSITION_NOMEM == disposition) goto out; /* - verify, by checking the Cumulative TSN Ack field of the * chunk, that all its outstanding DATA chunks have been * received by the SHUTDOWN sender. */ sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN, SCTP_BE32(chunk->subh.shutdown_hdr->cum_tsn_ack)); out: return disposition; } /* * sctp_sf_do_9_2_shut_ctsn * * Once an endpoint has reached the SHUTDOWN-RECEIVED state, * it MUST NOT send a SHUTDOWN in response to a ULP request. * The Cumulative TSN Ack of the received SHUTDOWN chunk * MUST be processed. */ sctp_disposition_t sctp_sf_do_9_2_shut_ctsn(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_shutdownhdr_t *sdh; __u32 ctsn; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the SHUTDOWN chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); sdh = (sctp_shutdownhdr_t *)chunk->skb->data; ctsn = ntohl(sdh->cum_tsn_ack); if (TSN_lt(ctsn, asoc->ctsn_ack_point)) { pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn, asoc->ctsn_ack_point); return SCTP_DISPOSITION_DISCARD; } /* If Cumulative TSN Ack beyond the max tsn currently * send, terminating the association and respond to the * sender with an ABORT. */ if (!TSN_lt(ctsn, asoc->next_tsn)) return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands); /* verify, by checking the Cumulative TSN Ack field of the * chunk, that all its outstanding DATA chunks have been * received by the SHUTDOWN sender. */ sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN, SCTP_BE32(sdh->cum_tsn_ack)); return SCTP_DISPOSITION_CONSUME; } /* RFC 2960 9.2 * If an endpoint is in SHUTDOWN-ACK-SENT state and receives an INIT chunk * (e.g., if the SHUTDOWN COMPLETE was lost) with source and destination * transport addresses (either in the IP addresses or in the INIT chunk) * that belong to this association, it should discard the INIT chunk and * retransmit the SHUTDOWN ACK chunk. */ sctp_disposition_t sctp_sf_do_9_2_reshutack(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = (struct sctp_chunk *) arg; struct sctp_chunk *reply; /* Make sure that the chunk has a valid length */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Since we are not going to really process this INIT, there * is no point in verifying chunk boundries. Just generate * the SHUTDOWN ACK. */ reply = sctp_make_shutdown_ack(asoc, chunk); if (NULL == reply) goto nomem; /* Set the transport for the SHUTDOWN ACK chunk and the timeout for * the T2-SHUTDOWN timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply)); /* and restart the T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * sctp_sf_do_ecn_cwr * * Section: Appendix A: Explicit Congestion Notification * * CWR: * * RFC 2481 details a specific bit for a sender to send in the header of * its next outbound TCP segment to indicate to its peer that it has * reduced its congestion window. This is termed the CWR bit. For * SCTP the same indication is made by including the CWR chunk. * This chunk contains one data element, i.e. the TSN number that * was sent in the ECNE chunk. This element represents the lowest * TSN number in the datagram that was originally marked with the * CE bit. * * Verification Tag: 8.5 Verification Tag [Normal verification] * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_ecn_cwr(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_cwrhdr_t *cwr; struct sctp_chunk *chunk = arg; u32 lowest_tsn; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); if (!sctp_chunk_length_valid(chunk, sizeof(sctp_ecne_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); cwr = (sctp_cwrhdr_t *) chunk->skb->data; skb_pull(chunk->skb, sizeof(sctp_cwrhdr_t)); lowest_tsn = ntohl(cwr->lowest_tsn); /* Does this CWR ack the last sent congestion notification? */ if (TSN_lte(asoc->last_ecne_tsn, lowest_tsn)) { /* Stop sending ECNE. */ sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CWR, SCTP_U32(lowest_tsn)); } return SCTP_DISPOSITION_CONSUME; } /* * sctp_sf_do_ecne * * Section: Appendix A: Explicit Congestion Notification * * ECN-Echo * * RFC 2481 details a specific bit for a receiver to send back in its * TCP acknowledgements to notify the sender of the Congestion * Experienced (CE) bit having arrived from the network. For SCTP this * same indication is made by including the ECNE chunk. This chunk * contains one data element, i.e. the lowest TSN associated with the IP * datagram marked with the CE bit..... * * Verification Tag: 8.5 Verification Tag [Normal verification] * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_ecne(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_ecnehdr_t *ecne; struct sctp_chunk *chunk = arg; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); if (!sctp_chunk_length_valid(chunk, sizeof(sctp_ecne_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); ecne = (sctp_ecnehdr_t *) chunk->skb->data; skb_pull(chunk->skb, sizeof(sctp_ecnehdr_t)); /* If this is a newer ECNE than the last CWR packet we sent out */ sctp_add_cmd_sf(commands, SCTP_CMD_ECN_ECNE, SCTP_U32(ntohl(ecne->lowest_tsn))); return SCTP_DISPOSITION_CONSUME; } /* * Section: 6.2 Acknowledgement on Reception of DATA Chunks * * The SCTP endpoint MUST always acknowledge the reception of each valid * DATA chunk. * * The guidelines on delayed acknowledgement algorithm specified in * Section 4.2 of [RFC2581] SHOULD be followed. Specifically, an * acknowledgement SHOULD be generated for at least every second packet * (not every second DATA chunk) received, and SHOULD be generated within * 200 ms of the arrival of any unacknowledged DATA chunk. In some * situations it may be beneficial for an SCTP transmitter to be more * conservative than the algorithms detailed in this document allow. * However, an SCTP transmitter MUST NOT be more aggressive than the * following algorithms allow. * * A SCTP receiver MUST NOT generate more than one SACK for every * incoming packet, other than to update the offered window as the * receiving application consumes new data. * * Verification Tag: 8.5 Verification Tag [Normal verification] * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_eat_data_6_2(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_arg_t force = SCTP_NOFORCE(); int error; if (!sctp_vtag_verify(chunk, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } if (!sctp_chunk_length_valid(chunk, sizeof(sctp_data_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); error = sctp_eat_data(asoc, chunk, commands); switch (error) { case SCTP_IERROR_NO_ERROR: break; case SCTP_IERROR_HIGH_TSN: case SCTP_IERROR_BAD_STREAM: SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS); goto discard_noforce; case SCTP_IERROR_DUP_TSN: case SCTP_IERROR_IGNORE_TSN: SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS); goto discard_force; case SCTP_IERROR_NO_DATA: return SCTP_DISPOSITION_ABORT; case SCTP_IERROR_PROTO_VIOLATION: return sctp_sf_abort_violation(net, ep, asoc, chunk, commands, (u8 *)chunk->subh.data_hdr, sizeof(sctp_datahdr_t)); default: BUG(); } if (chunk->chunk_hdr->flags & SCTP_DATA_SACK_IMM) force = SCTP_FORCE(); if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE)); } /* If this is the last chunk in a packet, we need to count it * toward sack generation. Note that we need to SACK every * OTHER packet containing data chunks, EVEN IF WE DISCARD * THEM. We elect to NOT generate SACK's if the chunk fails * the verification tag test. * * RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks * * The SCTP endpoint MUST always acknowledge the reception of * each valid DATA chunk. * * The guidelines on delayed acknowledgement algorithm * specified in Section 4.2 of [RFC2581] SHOULD be followed. * Specifically, an acknowledgement SHOULD be generated for at * least every second packet (not every second DATA chunk) * received, and SHOULD be generated within 200 ms of the * arrival of any unacknowledged DATA chunk. In some * situations it may be beneficial for an SCTP transmitter to * be more conservative than the algorithms detailed in this * document allow. However, an SCTP transmitter MUST NOT be * more aggressive than the following algorithms allow. */ if (chunk->end_of_packet) sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force); return SCTP_DISPOSITION_CONSUME; discard_force: /* RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks * * When a packet arrives with duplicate DATA chunk(s) and with * no new DATA chunk(s), the endpoint MUST immediately send a * SACK with no delay. If a packet arrives with duplicate * DATA chunk(s) bundled with new DATA chunks, the endpoint * MAY immediately send a SACK. Normally receipt of duplicate * DATA chunks will occur when the original SACK chunk was lost * and the peer's RTO has expired. The duplicate TSN number(s) * SHOULD be reported in the SACK as duplicate. */ /* In our case, we split the MAY SACK advice up whether or not * the last chunk is a duplicate.' */ if (chunk->end_of_packet) sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE()); return SCTP_DISPOSITION_DISCARD; discard_noforce: if (chunk->end_of_packet) sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force); return SCTP_DISPOSITION_DISCARD; } /* * sctp_sf_eat_data_fast_4_4 * * Section: 4 (4) * (4) In SHUTDOWN-SENT state the endpoint MUST acknowledge any received * DATA chunks without delay. * * Verification Tag: 8.5 Verification Tag [Normal verification] * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_eat_data_fast_4_4(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; int error; if (!sctp_vtag_verify(chunk, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } if (!sctp_chunk_length_valid(chunk, sizeof(sctp_data_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); error = sctp_eat_data(asoc, chunk, commands); switch (error) { case SCTP_IERROR_NO_ERROR: case SCTP_IERROR_HIGH_TSN: case SCTP_IERROR_DUP_TSN: case SCTP_IERROR_IGNORE_TSN: case SCTP_IERROR_BAD_STREAM: break; case SCTP_IERROR_NO_DATA: return SCTP_DISPOSITION_ABORT; case SCTP_IERROR_PROTO_VIOLATION: return sctp_sf_abort_violation(net, ep, asoc, chunk, commands, (u8 *)chunk->subh.data_hdr, sizeof(sctp_datahdr_t)); default: BUG(); } /* Go a head and force a SACK, since we are shutting down. */ /* Implementor's Guide. * * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately * respond to each received packet containing one or more DATA chunk(s) * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer */ if (chunk->end_of_packet) { /* We must delay the chunk creation since the cumulative * TSN has not been updated yet. */ sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE()); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); } return SCTP_DISPOSITION_CONSUME; } /* * Section: 6.2 Processing a Received SACK * D) Any time a SACK arrives, the endpoint performs the following: * * i) If Cumulative TSN Ack is less than the Cumulative TSN Ack Point, * then drop the SACK. Since Cumulative TSN Ack is monotonically * increasing, a SACK whose Cumulative TSN Ack is less than the * Cumulative TSN Ack Point indicates an out-of-order SACK. * * ii) Set rwnd equal to the newly received a_rwnd minus the number * of bytes still outstanding after processing the Cumulative TSN Ack * and the Gap Ack Blocks. * * iii) If the SACK is missing a TSN that was previously * acknowledged via a Gap Ack Block (e.g., the data receiver * reneged on the data), then mark the corresponding DATA chunk * as available for retransmit: Mark it as missing for fast * retransmit as described in Section 7.2.4 and if no retransmit * timer is running for the destination address to which the DATA * chunk was originally transmitted, then T3-rtx is started for * that destination address. * * Verification Tag: 8.5 Verification Tag [Normal verification] * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_eat_sack_6_2(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_sackhdr_t *sackh; __u32 ctsn; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the SACK chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_sack_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Pull the SACK chunk from the data buffer */ sackh = sctp_sm_pull_sack(chunk); /* Was this a bogus SACK? */ if (!sackh) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); chunk->subh.sack_hdr = sackh; ctsn = ntohl(sackh->cum_tsn_ack); /* i) If Cumulative TSN Ack is less than the Cumulative TSN * Ack Point, then drop the SACK. Since Cumulative TSN * Ack is monotonically increasing, a SACK whose * Cumulative TSN Ack is less than the Cumulative TSN Ack * Point indicates an out-of-order SACK. */ if (TSN_lt(ctsn, asoc->ctsn_ack_point)) { pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn, asoc->ctsn_ack_point); return SCTP_DISPOSITION_DISCARD; } /* If Cumulative TSN Ack beyond the max tsn currently * send, terminating the association and respond to the * sender with an ABORT. */ if (!TSN_lt(ctsn, asoc->next_tsn)) return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands); /* Return this SACK for further processing. */ sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK, SCTP_CHUNK(chunk)); /* Note: We do the rest of the work on the PROCESS_SACK * sideeffect. */ return SCTP_DISPOSITION_CONSUME; } /* * Generate an ABORT in response to a packet. * * Section: 8.4 Handle "Out of the blue" Packets, sctpimpguide 2.41 * * 8) The receiver should respond to the sender of the OOTB packet with * an ABORT. When sending the ABORT, the receiver of the OOTB packet * MUST fill in the Verification Tag field of the outbound packet * with the value found in the Verification Tag field of the OOTB * packet and set the T-bit in the Chunk Flags to indicate that the * Verification Tag is reflected. After sending this ABORT, the * receiver of the OOTB packet shall discard the OOTB packet and take * no further action. * * Verification Tag: * * The return value is the disposition of the chunk. */ static sctp_disposition_t sctp_sf_tabort_8_4_8(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_packet *packet = NULL; struct sctp_chunk *chunk = arg; struct sctp_chunk *abort; packet = sctp_ootb_pkt_new(net, asoc, chunk); if (!packet) return SCTP_DISPOSITION_NOMEM; /* Make an ABORT. The T bit will be set if the asoc * is NULL. */ abort = sctp_make_abort(asoc, chunk, 0); if (!abort) { sctp_ootb_pkt_free(packet); return SCTP_DISPOSITION_NOMEM; } /* Reflect vtag if T-Bit is set */ if (sctp_test_T_bit(abort)) packet->vtag = ntohl(chunk->sctp_hdr->vtag); /* Set the skb to the belonging sock for accounting. */ abort->skb->sk = ep->base.sk; sctp_packet_append_chunk(packet, abort); sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); return SCTP_DISPOSITION_CONSUME; } /* * Received an ERROR chunk from peer. Generate SCTP_REMOTE_ERROR * event as ULP notification for each cause included in the chunk. * * API 5.3.1.3 - SCTP_REMOTE_ERROR * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_operr_notify(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_errhdr_t *err; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the ERROR chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_operr_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); sctp_walk_errors(err, chunk->chunk_hdr); if ((void *)err != (void *)chunk->chunk_end) return sctp_sf_violation_paramlen(net, ep, asoc, type, arg, (void *)err, commands); sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_OPERR, SCTP_CHUNK(chunk)); return SCTP_DISPOSITION_CONSUME; } /* * Process an inbound SHUTDOWN ACK. * * From Section 9.2: * Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall * stop the T2-shutdown timer, send a SHUTDOWN COMPLETE chunk to its * peer, and remove all record of the association. * * The return value is the disposition. */ sctp_disposition_t sctp_sf_do_9_2_final(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_chunk *reply; struct sctp_ulpevent *ev; if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* 10.2 H) SHUTDOWN COMPLETE notification * * When SCTP completes the shutdown procedures (section 9.2) this * notification is passed to the upper layer. */ ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP, 0, 0, 0, NULL, GFP_ATOMIC); if (!ev) goto nomem; /* ...send a SHUTDOWN COMPLETE chunk to its peer, */ reply = sctp_make_shutdown_complete(asoc, chunk); if (!reply) goto nomem_chunk; /* Do all the commands now (after allocation), so that we * have consistent state if memory allocation failes */ sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); /* Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall * stop the T2-shutdown timer, */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_CLOSED)); SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); /* ...and remove all record of the association. */ sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL()); return SCTP_DISPOSITION_DELETE_TCB; nomem_chunk: sctp_ulpevent_free(ev); nomem: return SCTP_DISPOSITION_NOMEM; } /* * RFC 2960, 8.4 - Handle "Out of the blue" Packets, sctpimpguide 2.41. * * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should * respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE. * When sending the SHUTDOWN COMPLETE, the receiver of the OOTB * packet must fill in the Verification Tag field of the outbound * packet with the Verification Tag received in the SHUTDOWN ACK and * set the T-bit in the Chunk Flags to indicate that the Verification * Tag is reflected. * * 8) The receiver should respond to the sender of the OOTB packet with * an ABORT. When sending the ABORT, the receiver of the OOTB packet * MUST fill in the Verification Tag field of the outbound packet * with the value found in the Verification Tag field of the OOTB * packet and set the T-bit in the Chunk Flags to indicate that the * Verification Tag is reflected. After sending this ABORT, the * receiver of the OOTB packet shall discard the OOTB packet and take * no further action. */ sctp_disposition_t sctp_sf_ootb(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sk_buff *skb = chunk->skb; sctp_chunkhdr_t *ch; sctp_errhdr_t *err; __u8 *ch_end; int ootb_shut_ack = 0; int ootb_cookie_ack = 0; SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); ch = (sctp_chunkhdr_t *) chunk->chunk_hdr; do { /* Report violation if the chunk is less then minimal */ if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t)) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Report violation if chunk len overflows */ ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); if (ch_end > skb_tail_pointer(skb)) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Now that we know we at least have a chunk header, * do things that are type appropriate. */ if (SCTP_CID_SHUTDOWN_ACK == ch->type) ootb_shut_ack = 1; /* RFC 2960, Section 3.3.7 * Moreover, under any circumstances, an endpoint that * receives an ABORT MUST NOT respond to that ABORT by * sending an ABORT of its own. */ if (SCTP_CID_ABORT == ch->type) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR * or a COOKIE ACK the SCTP Packet should be silently * discarded. */ if (SCTP_CID_COOKIE_ACK == ch->type) ootb_cookie_ack = 1; if (SCTP_CID_ERROR == ch->type) { sctp_walk_errors(err, ch) { if (SCTP_ERROR_STALE_COOKIE == err->cause) { ootb_cookie_ack = 1; break; } } } ch = (sctp_chunkhdr_t *) ch_end; } while (ch_end < skb_tail_pointer(skb)); if (ootb_shut_ack) return sctp_sf_shut_8_4_5(net, ep, asoc, type, arg, commands); else if (ootb_cookie_ack) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); else return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands); } /* * Handle an "Out of the blue" SHUTDOWN ACK. * * Section: 8.4 5, sctpimpguide 2.41. * * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should * respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE. * When sending the SHUTDOWN COMPLETE, the receiver of the OOTB * packet must fill in the Verification Tag field of the outbound * packet with the Verification Tag received in the SHUTDOWN ACK and * set the T-bit in the Chunk Flags to indicate that the Verification * Tag is reflected. * * Inputs * (endpoint, asoc, type, arg, commands) * * Outputs * (sctp_disposition_t) * * The return value is the disposition of the chunk. */ static sctp_disposition_t sctp_sf_shut_8_4_5(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_packet *packet = NULL; struct sctp_chunk *chunk = arg; struct sctp_chunk *shut; packet = sctp_ootb_pkt_new(net, asoc, chunk); if (!packet) return SCTP_DISPOSITION_NOMEM; /* Make an SHUTDOWN_COMPLETE. * The T bit will be set if the asoc is NULL. */ shut = sctp_make_shutdown_complete(asoc, chunk); if (!shut) { sctp_ootb_pkt_free(packet); return SCTP_DISPOSITION_NOMEM; } /* Reflect vtag if T-Bit is set */ if (sctp_test_T_bit(shut)) packet->vtag = ntohl(chunk->sctp_hdr->vtag); /* Set the skb to the belonging sock for accounting. */ shut->skb->sk = ep->base.sk; sctp_packet_append_chunk(packet, shut); sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); /* If the chunk length is invalid, we don't want to process * the reset of the packet. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* We need to discard the rest of the packet to prevent * potential bomming attacks from additional bundled chunks. * This is documented in SCTP Threats ID. */ return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } /* * Handle SHUTDOWN ACK in COOKIE_ECHOED or COOKIE_WAIT state. * * Verification Tag: 8.5.1 E) Rules for packet carrying a SHUTDOWN ACK * If the receiver is in COOKIE-ECHOED or COOKIE-WAIT state the * procedures in section 8.4 SHOULD be followed, in other words it * should be treated as an Out Of The Blue packet. * [This means that we do NOT check the Verification Tag on these * chunks. --piggy ] * */ sctp_disposition_t sctp_sf_do_8_5_1_E_sa(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); /* Although we do have an association in this case, it corresponds * to a restarted association. So the packet is treated as an OOTB * packet and the state function that handles OOTB SHUTDOWN_ACK is * called with a NULL association. */ SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES); return sctp_sf_shut_8_4_5(net, ep, NULL, type, arg, commands); } /* ADDIP Section 4.2 Upon reception of an ASCONF Chunk. */ sctp_disposition_t sctp_sf_do_asconf(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_chunk *asconf_ack = NULL; struct sctp_paramhdr *err_param = NULL; sctp_addiphdr_t *hdr; __u32 serial; if (!sctp_vtag_verify(chunk, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } /* ADD-IP: Section 4.1.1 * This chunk MUST be sent in an authenticated way by using * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk * is received unauthenticated it MUST be silently discarded as * described in [I-D.ietf-tsvwg-sctp-auth]. */ if (!net->sctp.addip_noauth && !chunk->auth) return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands); /* Make sure that the ASCONF ADDIP chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_addip_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); hdr = (sctp_addiphdr_t *)chunk->skb->data; serial = ntohl(hdr->serial); /* Verify the ASCONF chunk before processing it. */ if (!sctp_verify_asconf(asoc, chunk, true, &err_param)) return sctp_sf_violation_paramlen(net, ep, asoc, type, arg, (void *)err_param, commands); /* ADDIP 5.2 E1) Compare the value of the serial number to the value * the endpoint stored in a new association variable * 'Peer-Serial-Number'. */ if (serial == asoc->peer.addip_serial + 1) { /* If this is the first instance of ASCONF in the packet, * we can clean our old ASCONF-ACKs. */ if (!chunk->has_asconf) sctp_assoc_clean_asconf_ack_cache(asoc); /* ADDIP 5.2 E4) When the Sequence Number matches the next one * expected, process the ASCONF as described below and after * processing the ASCONF Chunk, append an ASCONF-ACK Chunk to * the response packet and cache a copy of it (in the event it * later needs to be retransmitted). * * Essentially, do V1-V5. */ asconf_ack = sctp_process_asconf((struct sctp_association *) asoc, chunk); if (!asconf_ack) return SCTP_DISPOSITION_NOMEM; } else if (serial < asoc->peer.addip_serial + 1) { /* ADDIP 5.2 E2) * If the value found in the Sequence Number is less than the * ('Peer- Sequence-Number' + 1), simply skip to the next * ASCONF, and include in the outbound response packet * any previously cached ASCONF-ACK response that was * sent and saved that matches the Sequence Number of the * ASCONF. Note: It is possible that no cached ASCONF-ACK * Chunk exists. This will occur when an older ASCONF * arrives out of order. In such a case, the receiver * should skip the ASCONF Chunk and not include ASCONF-ACK * Chunk for that chunk. */ asconf_ack = sctp_assoc_lookup_asconf_ack(asoc, hdr->serial); if (!asconf_ack) return SCTP_DISPOSITION_DISCARD; /* Reset the transport so that we select the correct one * this time around. This is to make sure that we don't * accidentally use a stale transport that's been removed. */ asconf_ack->transport = NULL; } else { /* ADDIP 5.2 E5) Otherwise, the ASCONF Chunk is discarded since * it must be either a stale packet or from an attacker. */ return SCTP_DISPOSITION_DISCARD; } /* ADDIP 5.2 E6) The destination address of the SCTP packet * containing the ASCONF-ACK Chunks MUST be the source address of * the SCTP packet that held the ASCONF Chunks. * * To do this properly, we'll set the destination address of the chunk * and at the transmit time, will try look up the transport to use. * Since ASCONFs may be bundled, the correct transport may not be * created until we process the entire packet, thus this workaround. */ asconf_ack->dest = chunk->source; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack)); if (asoc->new_transport) { sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands); ((struct sctp_association *)asoc)->new_transport = NULL; } return SCTP_DISPOSITION_CONSUME; } /* * ADDIP Section 4.3 General rules for address manipulation * When building TLV parameters for the ASCONF Chunk that will add or * delete IP addresses the D0 to D13 rules should be applied: */ sctp_disposition_t sctp_sf_do_asconf_ack(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *asconf_ack = arg; struct sctp_chunk *last_asconf = asoc->addip_last_asconf; struct sctp_chunk *abort; struct sctp_paramhdr *err_param = NULL; sctp_addiphdr_t *addip_hdr; __u32 sent_serial, rcvd_serial; if (!sctp_vtag_verify(asconf_ack, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } /* ADD-IP, Section 4.1.2: * This chunk MUST be sent in an authenticated way by using * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk * is received unauthenticated it MUST be silently discarded as * described in [I-D.ietf-tsvwg-sctp-auth]. */ if (!net->sctp.addip_noauth && !asconf_ack->auth) return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands); /* Make sure that the ADDIP chunk has a valid length. */ if (!sctp_chunk_length_valid(asconf_ack, sizeof(sctp_addip_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); addip_hdr = (sctp_addiphdr_t *)asconf_ack->skb->data; rcvd_serial = ntohl(addip_hdr->serial); /* Verify the ASCONF-ACK chunk before processing it. */ if (!sctp_verify_asconf(asoc, asconf_ack, false, &err_param)) return sctp_sf_violation_paramlen(net, ep, asoc, type, arg, (void *)err_param, commands); if (last_asconf) { addip_hdr = (sctp_addiphdr_t *)last_asconf->subh.addip_hdr; sent_serial = ntohl(addip_hdr->serial); } else { sent_serial = asoc->addip_serial - 1; } /* D0) If an endpoint receives an ASCONF-ACK that is greater than or * equal to the next serial number to be used but no ASCONF chunk is * outstanding the endpoint MUST ABORT the association. Note that a * sequence number is greater than if it is no more than 2^^31-1 * larger than the current sequence number (using serial arithmetic). */ if (ADDIP_SERIAL_gte(rcvd_serial, sent_serial + 1) && !(asoc->addip_last_asconf)) { abort = sctp_make_abort(asoc, asconf_ack, sizeof(sctp_errhdr_t)); if (abort) { sctp_init_cause(abort, SCTP_ERROR_ASCONF_ACK, 0); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); } /* We are going to ABORT, so we might as well stop * processing the rest of the chunks in the packet. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO)); sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_ASCONF_ACK)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_ABORT; } if ((rcvd_serial == sent_serial) && asoc->addip_last_asconf) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO)); if (!sctp_process_asconf_ack((struct sctp_association *)asoc, asconf_ack)) { /* Successfully processed ASCONF_ACK. We can * release the next asconf if we have one. */ sctp_add_cmd_sf(commands, SCTP_CMD_SEND_NEXT_ASCONF, SCTP_NULL()); return SCTP_DISPOSITION_CONSUME; } abort = sctp_make_abort(asoc, asconf_ack, sizeof(sctp_errhdr_t)); if (abort) { sctp_init_cause(abort, SCTP_ERROR_RSRC_LOW, 0); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); } /* We are going to ABORT, so we might as well stop * processing the rest of the chunks in the packet. */ sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_ASCONF_ACK)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_ABORT; } return SCTP_DISPOSITION_DISCARD; } /* * PR-SCTP Section 3.6 Receiver Side Implementation of PR-SCTP * * When a FORWARD TSN chunk arrives, the data receiver MUST first update * its cumulative TSN point to the value carried in the FORWARD TSN * chunk, and then MUST further advance its cumulative TSN point locally * if possible. * After the above processing, the data receiver MUST stop reporting any * missing TSNs earlier than or equal to the new cumulative TSN point. * * Verification Tag: 8.5 Verification Tag [Normal verification] * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_eat_fwd_tsn(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_fwdtsn_hdr *fwdtsn_hdr; struct sctp_fwdtsn_skip *skip; __u16 len; __u32 tsn; if (!sctp_vtag_verify(chunk, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } if (!asoc->peer.prsctp_capable) return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands); /* Make sure that the FORWARD_TSN chunk has valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_fwdtsn_chunk))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data; chunk->subh.fwdtsn_hdr = fwdtsn_hdr; len = ntohs(chunk->chunk_hdr->length); len -= sizeof(struct sctp_chunkhdr); skb_pull(chunk->skb, len); tsn = ntohl(fwdtsn_hdr->new_cum_tsn); pr_debug("%s: TSN 0x%x\n", __func__, tsn); /* The TSN is too high--silently discard the chunk and count on it * getting retransmitted later. */ if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0) goto discard_noforce; /* Silently discard the chunk if stream-id is not valid */ sctp_walk_fwdtsn(skip, chunk) { if (ntohs(skip->stream) >= asoc->c.sinit_max_instreams) goto discard_noforce; } sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn)); if (len > sizeof(struct sctp_fwdtsn_hdr)) sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN, SCTP_CHUNK(chunk)); /* Count this as receiving DATA. */ if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE)); } /* FIXME: For now send a SACK, but DATA processing may * send another. */ sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_NOFORCE()); return SCTP_DISPOSITION_CONSUME; discard_noforce: return SCTP_DISPOSITION_DISCARD; } sctp_disposition_t sctp_sf_eat_fwd_tsn_fast( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_fwdtsn_hdr *fwdtsn_hdr; struct sctp_fwdtsn_skip *skip; __u16 len; __u32 tsn; if (!sctp_vtag_verify(chunk, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } if (!asoc->peer.prsctp_capable) return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands); /* Make sure that the FORWARD_TSN chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_fwdtsn_chunk))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data; chunk->subh.fwdtsn_hdr = fwdtsn_hdr; len = ntohs(chunk->chunk_hdr->length); len -= sizeof(struct sctp_chunkhdr); skb_pull(chunk->skb, len); tsn = ntohl(fwdtsn_hdr->new_cum_tsn); pr_debug("%s: TSN 0x%x\n", __func__, tsn); /* The TSN is too high--silently discard the chunk and count on it * getting retransmitted later. */ if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0) goto gen_shutdown; /* Silently discard the chunk if stream-id is not valid */ sctp_walk_fwdtsn(skip, chunk) { if (ntohs(skip->stream) >= asoc->c.sinit_max_instreams) goto gen_shutdown; } sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn)); if (len > sizeof(struct sctp_fwdtsn_hdr)) sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN, SCTP_CHUNK(chunk)); /* Go a head and force a SACK, since we are shutting down. */ gen_shutdown: /* Implementor's Guide. * * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately * respond to each received packet containing one or more DATA chunk(s) * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer */ sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE()); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); return SCTP_DISPOSITION_CONSUME; } /* * SCTP-AUTH Section 6.3 Receiving authenticated chukns * * The receiver MUST use the HMAC algorithm indicated in the HMAC * Identifier field. If this algorithm was not specified by the * receiver in the HMAC-ALGO parameter in the INIT or INIT-ACK chunk * during association setup, the AUTH chunk and all chunks after it MUST * be discarded and an ERROR chunk SHOULD be sent with the error cause * defined in Section 4.1. * * If an endpoint with no shared key receives a Shared Key Identifier * other than 0, it MUST silently discard all authenticated chunks. If * the endpoint has at least one endpoint pair shared key for the peer, * it MUST use the key specified by the Shared Key Identifier if a * key has been configured for that Shared Key Identifier. If no * endpoint pair shared key has been configured for that Shared Key * Identifier, all authenticated chunks MUST be silently discarded. * * Verification Tag: 8.5 Verification Tag [Normal verification] * * The return value is the disposition of the chunk. */ static sctp_ierror_t sctp_sf_authenticate(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, struct sctp_chunk *chunk) { struct sctp_authhdr *auth_hdr; struct sctp_hmac *hmac; unsigned int sig_len; __u16 key_id; __u8 *save_digest; __u8 *digest; /* Pull in the auth header, so we can do some more verification */ auth_hdr = (struct sctp_authhdr *)chunk->skb->data; chunk->subh.auth_hdr = auth_hdr; skb_pull(chunk->skb, sizeof(struct sctp_authhdr)); /* Make sure that we support the HMAC algorithm from the auth * chunk. */ if (!sctp_auth_asoc_verify_hmac_id(asoc, auth_hdr->hmac_id)) return SCTP_IERROR_AUTH_BAD_HMAC; /* Make sure that the provided shared key identifier has been * configured */ key_id = ntohs(auth_hdr->shkey_id); if (key_id != asoc->active_key_id && !sctp_auth_get_shkey(asoc, key_id)) return SCTP_IERROR_AUTH_BAD_KEYID; /* Make sure that the length of the signature matches what * we expect. */ sig_len = ntohs(chunk->chunk_hdr->length) - sizeof(sctp_auth_chunk_t); hmac = sctp_auth_get_hmac(ntohs(auth_hdr->hmac_id)); if (sig_len != hmac->hmac_len) return SCTP_IERROR_PROTO_VIOLATION; /* Now that we've done validation checks, we can compute and * verify the hmac. The steps involved are: * 1. Save the digest from the chunk. * 2. Zero out the digest in the chunk. * 3. Compute the new digest * 4. Compare saved and new digests. */ digest = auth_hdr->hmac; skb_pull(chunk->skb, sig_len); save_digest = kmemdup(digest, sig_len, GFP_ATOMIC); if (!save_digest) goto nomem; memset(digest, 0, sig_len); sctp_auth_calculate_hmac(asoc, chunk->skb, (struct sctp_auth_chunk *)chunk->chunk_hdr, GFP_ATOMIC); /* Discard the packet if the digests do not match */ if (memcmp(save_digest, digest, sig_len)) { kfree(save_digest); return SCTP_IERROR_BAD_SIG; } kfree(save_digest); chunk->auth = 1; return SCTP_IERROR_NO_ERROR; nomem: return SCTP_IERROR_NOMEM; } sctp_disposition_t sctp_sf_eat_auth(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_authhdr *auth_hdr; struct sctp_chunk *chunk = arg; struct sctp_chunk *err_chunk; sctp_ierror_t error; /* Make sure that the peer has AUTH capable */ if (!asoc->peer.auth_capable) return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands); if (!sctp_vtag_verify(chunk, asoc)) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG, SCTP_NULL()); return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); } /* Make sure that the AUTH chunk has valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_auth_chunk))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); auth_hdr = (struct sctp_authhdr *)chunk->skb->data; error = sctp_sf_authenticate(net, ep, asoc, type, chunk); switch (error) { case SCTP_IERROR_AUTH_BAD_HMAC: /* Generate the ERROR chunk and discard the rest * of the packet */ err_chunk = sctp_make_op_error(asoc, chunk, SCTP_ERROR_UNSUP_HMAC, &auth_hdr->hmac_id, sizeof(__u16), 0); if (err_chunk) { sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(err_chunk)); } /* Fall Through */ case SCTP_IERROR_AUTH_BAD_KEYID: case SCTP_IERROR_BAD_SIG: return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); case SCTP_IERROR_PROTO_VIOLATION: return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); case SCTP_IERROR_NOMEM: return SCTP_DISPOSITION_NOMEM; default: /* Prevent gcc warnings */ break; } if (asoc->active_key_id != ntohs(auth_hdr->shkey_id)) { struct sctp_ulpevent *ev; ev = sctp_ulpevent_make_authkey(asoc, ntohs(auth_hdr->shkey_id), SCTP_AUTH_NEWKEY, GFP_ATOMIC); if (!ev) return -ENOMEM; sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); } return SCTP_DISPOSITION_CONSUME; } /* * Process an unknown chunk. * * Section: 3.2. Also, 2.1 in the implementor's guide. * * Chunk Types are encoded such that the highest-order two bits specify * the action that must be taken if the processing endpoint does not * recognize the Chunk Type. * * 00 - Stop processing this SCTP packet and discard it, do not process * any further chunks within it. * * 01 - Stop processing this SCTP packet and discard it, do not process * any further chunks within it, and report the unrecognized * chunk in an 'Unrecognized Chunk Type'. * * 10 - Skip this chunk and continue processing. * * 11 - Skip this chunk and continue processing, but report in an ERROR * Chunk using the 'Unrecognized Chunk Type' cause of error. * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_unk_chunk(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *unk_chunk = arg; struct sctp_chunk *err_chunk; sctp_chunkhdr_t *hdr; pr_debug("%s: processing unknown chunk id:%d\n", __func__, type.chunk); if (!sctp_vtag_verify(unk_chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the chunk has a valid length. * Since we don't know the chunk type, we use a general * chunkhdr structure to make a comparison. */ if (!sctp_chunk_length_valid(unk_chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); switch (type.chunk & SCTP_CID_ACTION_MASK) { case SCTP_CID_ACTION_DISCARD: /* Discard the packet. */ return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); case SCTP_CID_ACTION_DISCARD_ERR: /* Generate an ERROR chunk as response. */ hdr = unk_chunk->chunk_hdr; err_chunk = sctp_make_op_error(asoc, unk_chunk, SCTP_ERROR_UNKNOWN_CHUNK, hdr, SCTP_PAD4(ntohs(hdr->length)), 0); if (err_chunk) { sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(err_chunk)); } /* Discard the packet. */ sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); return SCTP_DISPOSITION_CONSUME; case SCTP_CID_ACTION_SKIP: /* Skip the chunk. */ return SCTP_DISPOSITION_DISCARD; case SCTP_CID_ACTION_SKIP_ERR: /* Generate an ERROR chunk as response. */ hdr = unk_chunk->chunk_hdr; err_chunk = sctp_make_op_error(asoc, unk_chunk, SCTP_ERROR_UNKNOWN_CHUNK, hdr, SCTP_PAD4(ntohs(hdr->length)), 0); if (err_chunk) { sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(err_chunk)); } /* Skip the chunk. */ return SCTP_DISPOSITION_CONSUME; default: break; } return SCTP_DISPOSITION_DISCARD; } /* * Discard the chunk. * * Section: 0.2, 5.2.3, 5.2.5, 5.2.6, 6.0, 8.4.6, 8.5.1c, 9.2 * [Too numerous to mention...] * Verification Tag: No verification needed. * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_discard_chunk(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; /* Make sure that the chunk has a valid length. * Since we don't know the chunk type, we use a general * chunkhdr structure to make a comparison. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); pr_debug("%s: chunk:%d is discarded\n", __func__, type.chunk); return SCTP_DISPOSITION_DISCARD; } /* * Discard the whole packet. * * Section: 8.4 2) * * 2) If the OOTB packet contains an ABORT chunk, the receiver MUST * silently discard the OOTB packet and take no further action. * * Verification Tag: No verification necessary * * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_pdiscard(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS); sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL()); return SCTP_DISPOSITION_CONSUME; } /* * The other end is violating protocol. * * Section: Not specified * Verification Tag: Not specified * Inputs * (endpoint, asoc, chunk) * * Outputs * (asoc, reply_msg, msg_up, timers, counters) * * We simply tag the chunk as a violation. The state machine will log * the violation and continue. */ sctp_disposition_t sctp_sf_violation(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; /* Make sure that the chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); return SCTP_DISPOSITION_VIOLATION; } /* * Common function to handle a protocol violation. */ static sctp_disposition_t sctp_sf_abort_violation( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, void *arg, sctp_cmd_seq_t *commands, const __u8 *payload, const size_t paylen) { struct sctp_packet *packet = NULL; struct sctp_chunk *chunk = arg; struct sctp_chunk *abort = NULL; /* SCTP-AUTH, Section 6.3: * It should be noted that if the receiver wants to tear * down an association in an authenticated way only, the * handling of malformed packets should not result in * tearing down the association. * * This means that if we only want to abort associations * in an authenticated way (i.e AUTH+ABORT), then we * can't destroy this association just because the packet * was malformed. */ if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc)) goto discard; /* Make the abort chunk. */ abort = sctp_make_abort_violation(asoc, chunk, payload, paylen); if (!abort) goto nomem; if (asoc) { /* Treat INIT-ACK as a special case during COOKIE-WAIT. */ if (chunk->chunk_hdr->type == SCTP_CID_INIT_ACK && !asoc->peer.i.init_tag) { sctp_initack_chunk_t *initack; initack = (sctp_initack_chunk_t *)chunk->chunk_hdr; if (!sctp_chunk_length_valid(chunk, sizeof(sctp_initack_chunk_t))) abort->chunk_hdr->flags |= SCTP_CHUNK_FLAG_T; else { unsigned int inittag; inittag = ntohl(initack->init_hdr.init_tag); sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_INITTAG, SCTP_U32(inittag)); } } sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); if (asoc->state <= SCTP_STATE_COOKIE_ECHOED) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNREFUSED)); sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED, SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION)); } else { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION)); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); } } else { packet = sctp_ootb_pkt_new(net, asoc, chunk); if (!packet) goto nomem_pkt; if (sctp_test_T_bit(abort)) packet->vtag = ntohl(chunk->sctp_hdr->vtag); abort->skb->sk = ep->base.sk; sctp_packet_append_chunk(packet, abort); sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); } SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); discard: sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands); return SCTP_DISPOSITION_ABORT; nomem_pkt: sctp_chunk_free(abort); nomem: return SCTP_DISPOSITION_NOMEM; } /* * Handle a protocol violation when the chunk length is invalid. * "Invalid" length is identified as smaller than the minimal length a * given chunk can be. For example, a SACK chunk has invalid length * if its length is set to be smaller than the size of sctp_sack_chunk_t. * * We inform the other end by sending an ABORT with a Protocol Violation * error code. * * Section: Not specified * Verification Tag: Nothing to do * Inputs * (endpoint, asoc, chunk) * * Outputs * (reply_msg, msg_up, counters) * * Generate an ABORT chunk and terminate the association. */ static sctp_disposition_t sctp_sf_violation_chunklen( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { static const char err_str[] = "The following chunk had invalid length:"; return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str, sizeof(err_str)); } /* * Handle a protocol violation when the parameter length is invalid. * If the length is smaller than the minimum length of a given parameter, * or accumulated length in multi parameters exceeds the end of the chunk, * the length is considered as invalid. */ static sctp_disposition_t sctp_sf_violation_paramlen( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, void *ext, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; struct sctp_paramhdr *param = ext; struct sctp_chunk *abort = NULL; if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc)) goto discard; /* Make the abort chunk. */ abort = sctp_make_violation_paramlen(asoc, chunk, param); if (!abort) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION)); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); discard: sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands); return SCTP_DISPOSITION_ABORT; nomem: return SCTP_DISPOSITION_NOMEM; } /* Handle a protocol violation when the peer trying to advance the * cumulative tsn ack to a point beyond the max tsn currently sent. * * We inform the other end by sending an ABORT with a Protocol Violation * error code. */ static sctp_disposition_t sctp_sf_violation_ctsn( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { static const char err_str[] = "The cumulative tsn ack beyond the max tsn currently sent:"; return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str, sizeof(err_str)); } /* Handle protocol violation of an invalid chunk bundling. For example, * when we have an association and we receive bundled INIT-ACK, or * SHUDOWN-COMPLETE, our peer is clearly violationg the "MUST NOT bundle" * statement from the specs. Additionally, there might be an attacker * on the path and we may not want to continue this communication. */ static sctp_disposition_t sctp_sf_violation_chunk( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { static const char err_str[] = "The following chunk violates protocol:"; if (!asoc) return sctp_sf_violation(net, ep, asoc, type, arg, commands); return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str, sizeof(err_str)); } /*************************************************************************** * These are the state functions for handling primitive (Section 10) events. ***************************************************************************/ /* * sctp_sf_do_prm_asoc * * Section: 10.1 ULP-to-SCTP * B) Associate * * Format: ASSOCIATE(local SCTP instance name, destination transport addr, * outbound stream count) * -> association id [,destination transport addr list] [,outbound stream * count] * * This primitive allows the upper layer to initiate an association to a * specific peer endpoint. * * The peer endpoint shall be specified by one of the transport addresses * which defines the endpoint (see Section 1.4). If the local SCTP * instance has not been initialized, the ASSOCIATE is considered an * error. * [This is not relevant for the kernel implementation since we do all * initialization at boot time. It we hadn't initialized we wouldn't * get anywhere near this code.] * * An association id, which is a local handle to the SCTP association, * will be returned on successful establishment of the association. If * SCTP is not able to open an SCTP association with the peer endpoint, * an error is returned. * [In the kernel implementation, the struct sctp_association needs to * be created BEFORE causing this primitive to run.] * * Other association parameters may be returned, including the * complete destination transport addresses of the peer as well as the * outbound stream count of the local endpoint. One of the transport * address from the returned destination addresses will be selected by * the local endpoint as default primary path for sending SCTP packets * to this peer. The returned "destination transport addr list" can * be used by the ULP to change the default primary path or to force * sending a packet to a specific transport address. [All of this * stuff happens when the INIT ACK arrives. This is a NON-BLOCKING * function.] * * Mandatory attributes: * * o local SCTP instance name - obtained from the INITIALIZE operation. * [This is the argument asoc.] * o destination transport addr - specified as one of the transport * addresses of the peer endpoint with which the association is to be * established. * [This is asoc->peer.active_path.] * o outbound stream count - the number of outbound streams the ULP * would like to open towards this peer endpoint. * [BUG: This is not currently implemented.] * Optional attributes: * * None. * * The return value is a disposition. */ sctp_disposition_t sctp_sf_do_prm_asoc(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *repl; struct sctp_association *my_asoc; /* The comment below says that we enter COOKIE-WAIT AFTER * sending the INIT, but that doesn't actually work in our * implementation... */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_COOKIE_WAIT)); /* RFC 2960 5.1 Normal Establishment of an Association * * A) "A" first sends an INIT chunk to "Z". In the INIT, "A" * must provide its Verification Tag (Tag_A) in the Initiate * Tag field. Tag_A SHOULD be a random number in the range of * 1 to 4294967295 (see 5.3.1 for Tag value selection). ... */ repl = sctp_make_init(asoc, &asoc->base.bind_addr, GFP_ATOMIC, 0); if (!repl) goto nomem; /* Choose transport for INIT. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT, SCTP_CHUNK(repl)); /* Cast away the const modifier, as we want to just * rerun it through as a sideffect. */ my_asoc = (struct sctp_association *)asoc; sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(my_asoc)); /* After sending the INIT, "A" starts the T1-init timer and * enters the COOKIE-WAIT state. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * Process the SEND primitive. * * Section: 10.1 ULP-to-SCTP * E) Send * * Format: SEND(association id, buffer address, byte count [,context] * [,stream id] [,life time] [,destination transport address] * [,unorder flag] [,no-bundle flag] [,payload protocol-id] ) * -> result * * This is the main method to send user data via SCTP. * * Mandatory attributes: * * o association id - local handle to the SCTP association * * o buffer address - the location where the user message to be * transmitted is stored; * * o byte count - The size of the user data in number of bytes; * * Optional attributes: * * o context - an optional 32 bit integer that will be carried in the * sending failure notification to the ULP if the transportation of * this User Message fails. * * o stream id - to indicate which stream to send the data on. If not * specified, stream 0 will be used. * * o life time - specifies the life time of the user data. The user data * will not be sent by SCTP after the life time expires. This * parameter can be used to avoid efforts to transmit stale * user messages. SCTP notifies the ULP if the data cannot be * initiated to transport (i.e. sent to the destination via SCTP's * send primitive) within the life time variable. However, the * user data will be transmitted if SCTP has attempted to transmit a * chunk before the life time expired. * * o destination transport address - specified as one of the destination * transport addresses of the peer endpoint to which this packet * should be sent. Whenever possible, SCTP should use this destination * transport address for sending the packets, instead of the current * primary path. * * o unorder flag - this flag, if present, indicates that the user * would like the data delivered in an unordered fashion to the peer * (i.e., the U flag is set to 1 on all DATA chunks carrying this * message). * * o no-bundle flag - instructs SCTP not to bundle this user data with * other outbound DATA chunks. SCTP MAY still bundle even when * this flag is present, when faced with network congestion. * * o payload protocol-id - A 32 bit unsigned integer that is to be * passed to the peer indicating the type of payload protocol data * being transmitted. This value is passed as opaque data by SCTP. * * The return value is the disposition. */ sctp_disposition_t sctp_sf_do_prm_send(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_datamsg *msg = arg; sctp_add_cmd_sf(commands, SCTP_CMD_SEND_MSG, SCTP_DATAMSG(msg)); return SCTP_DISPOSITION_CONSUME; } /* * Process the SHUTDOWN primitive. * * Section: 10.1: * C) Shutdown * * Format: SHUTDOWN(association id) * -> result * * Gracefully closes an association. Any locally queued user data * will be delivered to the peer. The association will be terminated only * after the peer acknowledges all the SCTP packets sent. A success code * will be returned on successful termination of the association. If * attempting to terminate the association results in a failure, an error * code shall be returned. * * Mandatory attributes: * * o association id - local handle to the SCTP association * * Optional attributes: * * None. * * The return value is the disposition. */ sctp_disposition_t sctp_sf_do_9_2_prm_shutdown( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { int disposition; /* From 9.2 Shutdown of an Association * Upon receipt of the SHUTDOWN primitive from its upper * layer, the endpoint enters SHUTDOWN-PENDING state and * remains there until all outstanding data has been * acknowledged by its peer. The endpoint accepts no new data * from its upper layer, but retransmits data to the far end * if necessary to fill gaps. */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING)); disposition = SCTP_DISPOSITION_CONSUME; if (sctp_outq_is_empty(&asoc->outqueue)) { disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type, arg, commands); } return disposition; } /* * Process the ABORT primitive. * * Section: 10.1: * C) Abort * * Format: Abort(association id [, cause code]) * -> result * * Ungracefully closes an association. Any locally queued user data * will be discarded and an ABORT chunk is sent to the peer. A success code * will be returned on successful abortion of the association. If * attempting to abort the association results in a failure, an error * code shall be returned. * * Mandatory attributes: * * o association id - local handle to the SCTP association * * Optional attributes: * * o cause code - reason of the abort to be passed to the peer * * None. * * The return value is the disposition. */ sctp_disposition_t sctp_sf_do_9_1_prm_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* From 9.1 Abort of an Association * Upon receipt of the ABORT primitive from its upper * layer, the endpoint enters CLOSED state and * discard all outstanding data has been * acknowledged by its peer. The endpoint accepts no new data * from its upper layer, but retransmits data to the far end * if necessary to fill gaps. */ struct sctp_chunk *abort = arg; if (abort) sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); /* Even if we can't send the ABORT due to low memory delete the * TCB. This is a departure from our typical NOMEM handling. */ sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED)); /* Delete the established association. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_USER_ABORT)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_ABORT; } /* We tried an illegal operation on an association which is closed. */ sctp_disposition_t sctp_sf_error_closed(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR, SCTP_ERROR(-EINVAL)); return SCTP_DISPOSITION_CONSUME; } /* We tried an illegal operation on an association which is shutting * down. */ sctp_disposition_t sctp_sf_error_shutdown(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR, SCTP_ERROR(-ESHUTDOWN)); return SCTP_DISPOSITION_CONSUME; } /* * sctp_cookie_wait_prm_shutdown * * Section: 4 Note: 2 * Verification Tag: * Inputs * (endpoint, asoc) * * The RFC does not explicitly address this issue, but is the route through the * state table when someone issues a shutdown while in COOKIE_WAIT state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_cookie_wait_prm_shutdown( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_CLOSED)); SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS); sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL()); return SCTP_DISPOSITION_DELETE_TCB; } /* * sctp_cookie_echoed_prm_shutdown * * Section: 4 Note: 2 * Verification Tag: * Inputs * (endpoint, asoc) * * The RFC does not explcitly address this issue, but is the route through the * state table when someone issues a shutdown while in COOKIE_ECHOED state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_cookie_echoed_prm_shutdown( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* There is a single T1 timer, so we should be able to use * common function with the COOKIE-WAIT state. */ return sctp_sf_cookie_wait_prm_shutdown(net, ep, asoc, type, arg, commands); } /* * sctp_sf_cookie_wait_prm_abort * * Section: 4 Note: 2 * Verification Tag: * Inputs * (endpoint, asoc) * * The RFC does not explicitly address this issue, but is the route through the * state table when someone issues an abort while in COOKIE_WAIT state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_cookie_wait_prm_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *abort = arg; /* Stop T1-init timer */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); if (abort) sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_CLOSED)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); /* Even if we can't send the ABORT due to low memory delete the * TCB. This is a departure from our typical NOMEM handling. */ sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNREFUSED)); /* Delete the established association. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED, SCTP_PERR(SCTP_ERROR_USER_ABORT)); return SCTP_DISPOSITION_ABORT; } /* * sctp_sf_cookie_echoed_prm_abort * * Section: 4 Note: 3 * Verification Tag: * Inputs * (endpoint, asoc) * * The RFC does not explcitly address this issue, but is the route through the * state table when someone issues an abort while in COOKIE_ECHOED state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_cookie_echoed_prm_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* There is a single T1 timer, so we should be able to use * common function with the COOKIE-WAIT state. */ return sctp_sf_cookie_wait_prm_abort(net, ep, asoc, type, arg, commands); } /* * sctp_sf_shutdown_pending_prm_abort * * Inputs * (endpoint, asoc) * * The RFC does not explicitly address this issue, but is the route through the * state table when someone issues an abort while in SHUTDOWN-PENDING state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_shutdown_pending_prm_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* Stop the T5-shutdown guard timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands); } /* * sctp_sf_shutdown_sent_prm_abort * * Inputs * (endpoint, asoc) * * The RFC does not explicitly address this issue, but is the route through the * state table when someone issues an abort while in SHUTDOWN-SENT state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_shutdown_sent_prm_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* Stop the T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); /* Stop the T5-shutdown guard timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands); } /* * sctp_sf_cookie_echoed_prm_abort * * Inputs * (endpoint, asoc) * * The RFC does not explcitly address this issue, but is the route through the * state table when someone issues an abort while in COOKIE_ECHOED state. * * Outputs * (timers) */ sctp_disposition_t sctp_sf_shutdown_ack_sent_prm_abort( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { /* The same T2 timer, so we should be able to use * common function with the SHUTDOWN-SENT state. */ return sctp_sf_shutdown_sent_prm_abort(net, ep, asoc, type, arg, commands); } /* * Process the REQUESTHEARTBEAT primitive * * 10.1 ULP-to-SCTP * J) Request Heartbeat * * Format: REQUESTHEARTBEAT(association id, destination transport address) * * -> result * * Instructs the local endpoint to perform a HeartBeat on the specified * destination transport address of the given association. The returned * result should indicate whether the transmission of the HEARTBEAT * chunk to the destination address is successful. * * Mandatory attributes: * * o association id - local handle to the SCTP association * * o destination transport address - the transport address of the * association on which a heartbeat should be issued. */ sctp_disposition_t sctp_sf_do_prm_requestheartbeat( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type, (struct sctp_transport *)arg, commands)) return SCTP_DISPOSITION_NOMEM; /* * RFC 2960 (bis), section 8.3 * * D) Request an on-demand HEARTBEAT on a specific destination * transport address of a given association. * * The endpoint should increment the respective error counter of * the destination transport address each time a HEARTBEAT is sent * to that address and not acknowledged within one RTO. * */ sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT, SCTP_TRANSPORT(arg)); return SCTP_DISPOSITION_CONSUME; } /* * ADDIP Section 4.1 ASCONF Chunk Procedures * When an endpoint has an ASCONF signaled change to be sent to the * remote endpoint it should do A1 to A9 */ sctp_disposition_t sctp_sf_do_prm_asconf(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk)); sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk)); return SCTP_DISPOSITION_CONSUME; } /* RE-CONFIG Section 5.1 RECONF Chunk Procedures */ sctp_disposition_t sctp_sf_do_prm_reconf(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = arg; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk)); return SCTP_DISPOSITION_CONSUME; } /* * Ignore the primitive event * * The return value is the disposition of the primitive. */ sctp_disposition_t sctp_sf_ignore_primitive( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { pr_debug("%s: primitive type:%d is ignored\n", __func__, type.primitive); return SCTP_DISPOSITION_DISCARD; } /*************************************************************************** * These are the state functions for the OTHER events. ***************************************************************************/ /* * When the SCTP stack has no more user data to send or retransmit, this * notification is given to the user. Also, at the time when a user app * subscribes to this event, if there is no data to be sent or * retransmit, the stack will immediately send up this notification. */ sctp_disposition_t sctp_sf_do_no_pending_tsn( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_ulpevent *event; event = sctp_ulpevent_make_sender_dry_event(asoc, GFP_ATOMIC); if (!event) return SCTP_DISPOSITION_NOMEM; sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(event)); return SCTP_DISPOSITION_CONSUME; } /* * Start the shutdown negotiation. * * From Section 9.2: * Once all its outstanding data has been acknowledged, the endpoint * shall send a SHUTDOWN chunk to its peer including in the Cumulative * TSN Ack field the last sequential TSN it has received from the peer. * It shall then start the T2-shutdown timer and enter the SHUTDOWN-SENT * state. If the timer expires, the endpoint must re-send the SHUTDOWN * with the updated last sequential TSN received from its peer. * * The return value is the disposition. */ sctp_disposition_t sctp_sf_do_9_2_start_shutdown( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *reply; /* Once all its outstanding data has been acknowledged, the * endpoint shall send a SHUTDOWN chunk to its peer including * in the Cumulative TSN Ack field the last sequential TSN it * has received from the peer. */ reply = sctp_make_shutdown(asoc, NULL); if (!reply) goto nomem; /* Set the transport for the SHUTDOWN chunk and the timeout for the * T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply)); /* It shall then start the T2-shutdown timer */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); /* RFC 4960 Section 9.2 * The sender of the SHUTDOWN MAY also start an overall guard timer * 'T5-shutdown-guard' to bound the overall time for shutdown sequence. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE)); /* and enter the SHUTDOWN-SENT state. */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_SHUTDOWN_SENT)); /* sctp-implguide 2.10 Issues with Heartbeating and failover * * HEARTBEAT ... is discontinued after sending either SHUTDOWN * or SHUTDOWN-ACK. */ sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * Generate a SHUTDOWN ACK now that everything is SACK'd. * * From Section 9.2: * * If it has no more outstanding DATA chunks, the SHUTDOWN receiver * shall send a SHUTDOWN ACK and start a T2-shutdown timer of its own, * entering the SHUTDOWN-ACK-SENT state. If the timer expires, the * endpoint must re-send the SHUTDOWN ACK. * * The return value is the disposition. */ sctp_disposition_t sctp_sf_do_9_2_shutdown_ack( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = (struct sctp_chunk *) arg; struct sctp_chunk *reply; /* There are 2 ways of getting here: * 1) called in response to a SHUTDOWN chunk * 2) called when SCTP_EVENT_NO_PENDING_TSN event is issued. * * For the case (2), the arg parameter is set to NULL. We need * to check that we have a chunk before accessing it's fields. */ if (chunk) { if (!sctp_vtag_verify(chunk, asoc)) return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands); /* Make sure that the SHUTDOWN chunk has a valid length. */ if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk_t))) return sctp_sf_violation_chunklen(net, ep, asoc, type, arg, commands); } /* If it has no more outstanding DATA chunks, the SHUTDOWN receiver * shall send a SHUTDOWN ACK ... */ reply = sctp_make_shutdown_ack(asoc, chunk); if (!reply) goto nomem; /* Set the transport for the SHUTDOWN ACK chunk and the timeout for * the T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply)); /* and start/restart a T2-shutdown timer of its own, */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE)); /* Enter the SHUTDOWN-ACK-SENT state. */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_SHUTDOWN_ACK_SENT)); /* sctp-implguide 2.10 Issues with Heartbeating and failover * * HEARTBEAT ... is discontinued after sending either SHUTDOWN * or SHUTDOWN-ACK. */ sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * Ignore the event defined as other * * The return value is the disposition of the event. */ sctp_disposition_t sctp_sf_ignore_other(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { pr_debug("%s: the event other type:%d is ignored\n", __func__, type.other); return SCTP_DISPOSITION_DISCARD; } /************************************************************ * These are the state functions for handling timeout events. ************************************************************/ /* * RTX Timeout * * Section: 6.3.3 Handle T3-rtx Expiration * * Whenever the retransmission timer T3-rtx expires for a destination * address, do the following: * [See below] * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_do_6_3_3_rtx(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_transport *transport = arg; SCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS); if (asoc->overall_error_count >= asoc->max_retrans) { if (asoc->peer.zero_window_announced && asoc->state == SCTP_STATE_SHUTDOWN_PENDING) { /* * We are here likely because the receiver had its rwnd * closed for a while and we have not been able to * transmit the locally queued data within the maximum * retransmission attempts limit. Start the T5 * shutdown guard timer to give the receiver one last * chance and some additional time to recover before * aborting. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START_ONCE, SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD)); } else { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_DELETE_TCB; } } /* E1) For the destination address for which the timer * expires, adjust its ssthresh with rules defined in Section * 7.2.3 and set the cwnd <- MTU. */ /* E2) For the destination address for which the timer * expires, set RTO <- RTO * 2 ("back off the timer"). The * maximum value discussed in rule C7 above (RTO.max) may be * used to provide an upper bound to this doubling operation. */ /* E3) Determine how many of the earliest (i.e., lowest TSN) * outstanding DATA chunks for the address for which the * T3-rtx has expired will fit into a single packet, subject * to the MTU constraint for the path corresponding to the * destination transport address to which the retransmission * is being sent (this may be different from the address for * which the timer expires [see Section 6.4]). Call this * value K. Bundle and retransmit those K DATA chunks in a * single packet to the destination endpoint. * * Note: Any DATA chunks that were sent to the address for * which the T3-rtx timer expired but did not fit in one MTU * (rule E3 above), should be marked for retransmission and * sent as soon as cwnd allows (normally when a SACK arrives). */ /* Do some failure management (Section 8.2). */ sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport)); /* NB: Rules E4 and F1 are implicit in R1. */ sctp_add_cmd_sf(commands, SCTP_CMD_RETRAN, SCTP_TRANSPORT(transport)); return SCTP_DISPOSITION_CONSUME; } /* * Generate delayed SACK on timeout * * Section: 6.2 Acknowledgement on Reception of DATA Chunks * * The guidelines on delayed acknowledgement algorithm specified in * Section 4.2 of [RFC2581] SHOULD be followed. Specifically, an * acknowledgement SHOULD be generated for at least every second packet * (not every second DATA chunk) received, and SHOULD be generated * within 200 ms of the arrival of any unacknowledged DATA chunk. In * some situations it may be beneficial for an SCTP transmitter to be * more conservative than the algorithms detailed in this document * allow. However, an SCTP transmitter MUST NOT be more aggressive than * the following algorithms allow. */ sctp_disposition_t sctp_sf_do_6_2_sack(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { SCTP_INC_STATS(net, SCTP_MIB_DELAY_SACK_EXPIREDS); sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE()); return SCTP_DISPOSITION_CONSUME; } /* * sctp_sf_t1_init_timer_expire * * Section: 4 Note: 2 * Verification Tag: * Inputs * (endpoint, asoc) * * RFC 2960 Section 4 Notes * 2) If the T1-init timer expires, the endpoint MUST retransmit INIT * and re-start the T1-init timer without changing state. This MUST * be repeated up to 'Max.Init.Retransmits' times. After that, the * endpoint MUST abort the initialization process and report the * error to SCTP user. * * Outputs * (timers, events) * */ sctp_disposition_t sctp_sf_t1_init_timer_expire(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *repl = NULL; struct sctp_bind_addr *bp; int attempts = asoc->init_err_counter + 1; pr_debug("%s: timer T1 expired (INIT)\n", __func__); SCTP_INC_STATS(net, SCTP_MIB_T1_INIT_EXPIREDS); if (attempts <= asoc->max_init_attempts) { bp = (struct sctp_bind_addr *) &asoc->base.bind_addr; repl = sctp_make_init(asoc, bp, GFP_ATOMIC, 0); if (!repl) return SCTP_DISPOSITION_NOMEM; /* Choose transport for INIT. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT, SCTP_CHUNK(repl)); /* Issue a sideeffect to do the needed accounting. */ sctp_add_cmd_sf(commands, SCTP_CMD_INIT_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); } else { pr_debug("%s: giving up on INIT, attempts:%d " "max_init_attempts:%d\n", __func__, attempts, asoc->max_init_attempts); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); return SCTP_DISPOSITION_DELETE_TCB; } return SCTP_DISPOSITION_CONSUME; } /* * sctp_sf_t1_cookie_timer_expire * * Section: 4 Note: 2 * Verification Tag: * Inputs * (endpoint, asoc) * * RFC 2960 Section 4 Notes * 3) If the T1-cookie timer expires, the endpoint MUST retransmit * COOKIE ECHO and re-start the T1-cookie timer without changing * state. This MUST be repeated up to 'Max.Init.Retransmits' times. * After that, the endpoint MUST abort the initialization process and * report the error to SCTP user. * * Outputs * (timers, events) * */ sctp_disposition_t sctp_sf_t1_cookie_timer_expire(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *repl = NULL; int attempts = asoc->init_err_counter + 1; pr_debug("%s: timer T1 expired (COOKIE-ECHO)\n", __func__); SCTP_INC_STATS(net, SCTP_MIB_T1_COOKIE_EXPIREDS); if (attempts <= asoc->max_init_attempts) { repl = sctp_make_cookie_echo(asoc, NULL); if (!repl) return SCTP_DISPOSITION_NOMEM; sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT, SCTP_CHUNK(repl)); /* Issue a sideeffect to do the needed accounting. */ sctp_add_cmd_sf(commands, SCTP_CMD_COOKIEECHO_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); } else { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); return SCTP_DISPOSITION_DELETE_TCB; } return SCTP_DISPOSITION_CONSUME; } /* RFC2960 9.2 If the timer expires, the endpoint must re-send the SHUTDOWN * with the updated last sequential TSN received from its peer. * * An endpoint should limit the number of retransmissions of the * SHUTDOWN chunk to the protocol parameter 'Association.Max.Retrans'. * If this threshold is exceeded the endpoint should destroy the TCB and * MUST report the peer endpoint unreachable to the upper layer (and * thus the association enters the CLOSED state). The reception of any * packet from its peer (i.e. as the peer sends all of its queued DATA * chunks) should clear the endpoint's retransmission count and restart * the T2-Shutdown timer, giving its peer ample opportunity to transmit * all of its queued DATA chunks that have not yet been sent. */ sctp_disposition_t sctp_sf_t2_timer_expire(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *reply = NULL; pr_debug("%s: timer T2 expired\n", __func__); SCTP_INC_STATS(net, SCTP_MIB_T2_SHUTDOWN_EXPIREDS); ((struct sctp_association *)asoc)->shutdown_retries++; if (asoc->overall_error_count >= asoc->max_retrans) { sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); /* Note: CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */ sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_DELETE_TCB; } switch (asoc->state) { case SCTP_STATE_SHUTDOWN_SENT: reply = sctp_make_shutdown(asoc, NULL); break; case SCTP_STATE_SHUTDOWN_ACK_SENT: reply = sctp_make_shutdown_ack(asoc, NULL); break; default: BUG(); break; } if (!reply) goto nomem; /* Do some failure management (Section 8.2). * If we remove the transport an SHUTDOWN was last sent to, don't * do failure management. */ if (asoc->shutdown_last_sent_to) sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(asoc->shutdown_last_sent_to)); /* Set the transport for the SHUTDOWN/ACK chunk and the timeout for * the T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply)); /* Restart the T2-shutdown timer. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); return SCTP_DISPOSITION_CONSUME; nomem: return SCTP_DISPOSITION_NOMEM; } /* * ADDIP Section 4.1 ASCONF CHunk Procedures * If the T4 RTO timer expires the endpoint should do B1 to B5 */ sctp_disposition_t sctp_sf_t4_timer_expire( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *chunk = asoc->addip_last_asconf; struct sctp_transport *transport = chunk->transport; SCTP_INC_STATS(net, SCTP_MIB_T4_RTO_EXPIREDS); /* ADDIP 4.1 B1) Increment the error counters and perform path failure * detection on the appropriate destination address as defined in * RFC2960 [5] section 8.1 and 8.2. */ if (transport) sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport)); /* Reconfig T4 timer and transport. */ sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk)); /* ADDIP 4.1 B2) Increment the association error counters and perform * endpoint failure detection on the association as defined in * RFC2960 [5] section 8.1 and 8.2. * association error counter is incremented in SCTP_CMD_STRIKE. */ if (asoc->overall_error_count >= asoc->max_retrans) { sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP, SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO)); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_ABORT; } /* ADDIP 4.1 B3) Back-off the destination address RTO value to which * the ASCONF chunk was sent by doubling the RTO timer value. * This is done in SCTP_CMD_STRIKE. */ /* ADDIP 4.1 B4) Re-transmit the ASCONF Chunk last sent and if possible * choose an alternate destination address (please refer to RFC2960 * [5] section 6.4.1). An endpoint MUST NOT add new parameters to this * chunk, it MUST be the same (including its serial number) as the last * ASCONF sent. */ sctp_chunk_hold(asoc->addip_last_asconf); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asoc->addip_last_asconf)); /* ADDIP 4.1 B5) Restart the T-4 RTO timer. Note that if a different * destination is selected, then the RTO used will be that of the new * destination address. */ sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART, SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO)); return SCTP_DISPOSITION_CONSUME; } /* sctpimpguide-05 Section 2.12.2 * The sender of the SHUTDOWN MAY also start an overall guard timer * 'T5-shutdown-guard' to bound the overall time for shutdown sequence. * At the expiration of this timer the sender SHOULD abort the association * by sending an ABORT chunk. */ sctp_disposition_t sctp_sf_t5_timer_expire(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { struct sctp_chunk *reply = NULL; pr_debug("%s: timer T5 expired\n", __func__); SCTP_INC_STATS(net, SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS); reply = sctp_make_abort(asoc, NULL, 0); if (!reply) goto nomem; sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply)); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ETIMEDOUT)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_ERROR)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_DISPOSITION_DELETE_TCB; nomem: return SCTP_DISPOSITION_NOMEM; } /* Handle expiration of AUTOCLOSE timer. When the autoclose timer expires, * the association is automatically closed by starting the shutdown process. * The work that needs to be done is same as when SHUTDOWN is initiated by * the user. So this routine looks same as sctp_sf_do_9_2_prm_shutdown(). */ sctp_disposition_t sctp_sf_autoclose_timer_expire( struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { int disposition; SCTP_INC_STATS(net, SCTP_MIB_AUTOCLOSE_EXPIREDS); /* From 9.2 Shutdown of an Association * Upon receipt of the SHUTDOWN primitive from its upper * layer, the endpoint enters SHUTDOWN-PENDING state and * remains there until all outstanding data has been * acknowledged by its peer. The endpoint accepts no new data * from its upper layer, but retransmits data to the far end * if necessary to fill gaps. */ sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING)); disposition = SCTP_DISPOSITION_CONSUME; if (sctp_outq_is_empty(&asoc->outqueue)) { disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type, arg, commands); } return disposition; } /***************************************************************************** * These are sa state functions which could apply to all types of events. ****************************************************************************/ /* * This table entry is not implemented. * * Inputs * (endpoint, asoc, chunk) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_not_impl(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { return SCTP_DISPOSITION_NOT_IMPL; } /* * This table entry represents a bug. * * Inputs * (endpoint, asoc, chunk) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_bug(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { return SCTP_DISPOSITION_BUG; } /* * This table entry represents the firing of a timer in the wrong state. * Since timer deletion cannot be guaranteed a timer 'may' end up firing * when the association is in the wrong state. This event should * be ignored, so as to prevent any rearming of the timer. * * Inputs * (endpoint, asoc, chunk) * * The return value is the disposition of the chunk. */ sctp_disposition_t sctp_sf_timer_ignore(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const sctp_subtype_t type, void *arg, sctp_cmd_seq_t *commands) { pr_debug("%s: timer %d ignored\n", __func__, type.chunk); return SCTP_DISPOSITION_CONSUME; } /******************************************************************** * 2nd Level Abstractions ********************************************************************/ /* Pull the SACK chunk based on the SACK header. */ static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk) { struct sctp_sackhdr *sack; unsigned int len; __u16 num_blocks; __u16 num_dup_tsns; /* Protect ourselves from reading too far into * the skb from a bogus sender. */ sack = (struct sctp_sackhdr *) chunk->skb->data; num_blocks = ntohs(sack->num_gap_ack_blocks); num_dup_tsns = ntohs(sack->num_dup_tsns); len = sizeof(struct sctp_sackhdr); len += (num_blocks + num_dup_tsns) * sizeof(__u32); if (len > chunk->skb->len) return NULL; skb_pull(chunk->skb, len); return sack; } /* Create an ABORT packet to be sent as a response, with the specified * error causes. */ static struct sctp_packet *sctp_abort_pkt_new(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, struct sctp_chunk *chunk, const void *payload, size_t paylen) { struct sctp_packet *packet; struct sctp_chunk *abort; packet = sctp_ootb_pkt_new(net, asoc, chunk); if (packet) { /* Make an ABORT. * The T bit will be set if the asoc is NULL. */ abort = sctp_make_abort(asoc, chunk, paylen); if (!abort) { sctp_ootb_pkt_free(packet); return NULL; } /* Reflect vtag if T-Bit is set */ if (sctp_test_T_bit(abort)) packet->vtag = ntohl(chunk->sctp_hdr->vtag); /* Add specified error causes, i.e., payload, to the * end of the chunk. */ sctp_addto_chunk(abort, paylen, payload); /* Set the skb to the belonging sock for accounting. */ abort->skb->sk = ep->base.sk; sctp_packet_append_chunk(packet, abort); } return packet; } /* Allocate a packet for responding in the OOTB conditions. */ static struct sctp_packet *sctp_ootb_pkt_new(struct net *net, const struct sctp_association *asoc, const struct sctp_chunk *chunk) { struct sctp_packet *packet; struct sctp_transport *transport; __u16 sport; __u16 dport; __u32 vtag; /* Get the source and destination port from the inbound packet. */ sport = ntohs(chunk->sctp_hdr->dest); dport = ntohs(chunk->sctp_hdr->source); /* The V-tag is going to be the same as the inbound packet if no * association exists, otherwise, use the peer's vtag. */ if (asoc) { /* Special case the INIT-ACK as there is no peer's vtag * yet. */ switch (chunk->chunk_hdr->type) { case SCTP_CID_INIT_ACK: { sctp_initack_chunk_t *initack; initack = (sctp_initack_chunk_t *)chunk->chunk_hdr; vtag = ntohl(initack->init_hdr.init_tag); break; } default: vtag = asoc->peer.i.init_tag; break; } } else { /* Special case the INIT and stale COOKIE_ECHO as there is no * vtag yet. */ switch (chunk->chunk_hdr->type) { case SCTP_CID_INIT: { sctp_init_chunk_t *init; init = (sctp_init_chunk_t *)chunk->chunk_hdr; vtag = ntohl(init->init_hdr.init_tag); break; } default: vtag = ntohl(chunk->sctp_hdr->vtag); break; } } /* Make a transport for the bucket, Eliza... */ transport = sctp_transport_new(net, sctp_source(chunk), GFP_ATOMIC); if (!transport) goto nomem; /* Cache a route for the transport with the chunk's destination as * the source address. */ sctp_transport_route(transport, (union sctp_addr *)&chunk->dest, sctp_sk(net->sctp.ctl_sock)); packet = &transport->packet; sctp_packet_init(packet, transport, sport, dport); sctp_packet_config(packet, vtag, 0); return packet; nomem: return NULL; } /* Free the packet allocated earlier for responding in the OOTB condition. */ void sctp_ootb_pkt_free(struct sctp_packet *packet) { sctp_transport_free(packet->transport); } /* Send a stale cookie error when a invalid COOKIE ECHO chunk is found */ static void sctp_send_stale_cookie_err(struct net *net, const struct sctp_endpoint *ep, const struct sctp_association *asoc, const struct sctp_chunk *chunk, sctp_cmd_seq_t *commands, struct sctp_chunk *err_chunk) { struct sctp_packet *packet; if (err_chunk) { packet = sctp_ootb_pkt_new(net, asoc, chunk); if (packet) { struct sctp_signed_cookie *cookie; /* Override the OOTB vtag from the cookie. */ cookie = chunk->subh.cookie_hdr; packet->vtag = cookie->c.peer_vtag; /* Set the skb to the belonging sock for accounting. */ err_chunk->skb->sk = ep->base.sk; sctp_packet_append_chunk(packet, err_chunk); sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(packet)); SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS); } else sctp_chunk_free (err_chunk); } } /* Process a data chunk */ static int sctp_eat_data(const struct sctp_association *asoc, struct sctp_chunk *chunk, sctp_cmd_seq_t *commands) { sctp_datahdr_t *data_hdr; struct sctp_chunk *err; size_t datalen; sctp_verb_t deliver; int tmp; __u32 tsn; struct sctp_tsnmap *map = (struct sctp_tsnmap *)&asoc->peer.tsn_map; struct sock *sk = asoc->base.sk; struct net *net = sock_net(sk); u16 ssn; u16 sid; u8 ordered = 0; data_hdr = chunk->subh.data_hdr = (sctp_datahdr_t *)chunk->skb->data; skb_pull(chunk->skb, sizeof(sctp_datahdr_t)); tsn = ntohl(data_hdr->tsn); pr_debug("%s: TSN 0x%x\n", __func__, tsn); /* ASSERT: Now skb->data is really the user data. */ /* Process ECN based congestion. * * Since the chunk structure is reused for all chunks within * a packet, we use ecn_ce_done to track if we've already * done CE processing for this packet. * * We need to do ECN processing even if we plan to discard the * chunk later. */ if (asoc->peer.ecn_capable && !chunk->ecn_ce_done) { struct sctp_af *af = SCTP_INPUT_CB(chunk->skb)->af; chunk->ecn_ce_done = 1; if (af->is_ce(sctp_gso_headskb(chunk->skb))) { /* Do real work as sideffect. */ sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE, SCTP_U32(tsn)); } } tmp = sctp_tsnmap_check(&asoc->peer.tsn_map, tsn); if (tmp < 0) { /* The TSN is too high--silently discard the chunk and * count on it getting retransmitted later. */ if (chunk->asoc) chunk->asoc->stats.outofseqtsns++; return SCTP_IERROR_HIGH_TSN; } else if (tmp > 0) { /* This is a duplicate. Record it. */ sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_DUP, SCTP_U32(tsn)); return SCTP_IERROR_DUP_TSN; } /* This is a new TSN. */ /* Discard if there is no room in the receive window. * Actually, allow a little bit of overflow (up to a MTU). */ datalen = ntohs(chunk->chunk_hdr->length); datalen -= sizeof(sctp_data_chunk_t); deliver = SCTP_CMD_CHUNK_ULP; /* Think about partial delivery. */ if ((datalen >= asoc->rwnd) && (!asoc->ulpq.pd_mode)) { /* Even if we don't accept this chunk there is * memory pressure. */ sctp_add_cmd_sf(commands, SCTP_CMD_PART_DELIVER, SCTP_NULL()); } /* Spill over rwnd a little bit. Note: While allowed, this spill over * seems a bit troublesome in that frag_point varies based on * PMTU. In cases, such as loopback, this might be a rather * large spill over. */ if ((!chunk->data_accepted) && (!asoc->rwnd || asoc->rwnd_over || (datalen > asoc->rwnd + asoc->frag_point))) { /* If this is the next TSN, consider reneging to make * room. Note: Playing nice with a confused sender. A * malicious sender can still eat up all our buffer * space and in the future we may want to detect and * do more drastic reneging. */ if (sctp_tsnmap_has_gap(map) && (sctp_tsnmap_get_ctsn(map) + 1) == tsn) { pr_debug("%s: reneging for tsn:%u\n", __func__, tsn); deliver = SCTP_CMD_RENEGE; } else { pr_debug("%s: discard tsn:%u len:%zu, rwnd:%d\n", __func__, tsn, datalen, asoc->rwnd); return SCTP_IERROR_IGNORE_TSN; } } /* * Also try to renege to limit our memory usage in the event that * we are under memory pressure * If we can't renege, don't worry about it, the sk_rmem_schedule * in sctp_ulpevent_make_rcvmsg will drop the frame if we grow our * memory usage too much */ if (*sk->sk_prot_creator->memory_pressure) { if (sctp_tsnmap_has_gap(map) && (sctp_tsnmap_get_ctsn(map) + 1) == tsn) { pr_debug("%s: under pressure, reneging for tsn:%u\n", __func__, tsn); deliver = SCTP_CMD_RENEGE; } } /* * Section 3.3.10.9 No User Data (9) * * Cause of error * --------------- * No User Data: This error cause is returned to the originator of a * DATA chunk if a received DATA chunk has no user data. */ if (unlikely(0 == datalen)) { err = sctp_make_abort_no_data(asoc, chunk, tsn); if (err) { sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(err)); } /* We are going to ABORT, so we might as well stop * processing the rest of the chunks in the packet. */ sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL()); sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNABORTED)); sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(SCTP_ERROR_NO_DATA)); SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS); SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB); return SCTP_IERROR_NO_DATA; } chunk->data_accepted = 1; /* Note: Some chunks may get overcounted (if we drop) or overcounted * if we renege and the chunk arrives again. */ if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) { SCTP_INC_STATS(net, SCTP_MIB_INUNORDERCHUNKS); if (chunk->asoc) chunk->asoc->stats.iuodchunks++; } else { SCTP_INC_STATS(net, SCTP_MIB_INORDERCHUNKS); if (chunk->asoc) chunk->asoc->stats.iodchunks++; ordered = 1; } /* RFC 2960 6.5 Stream Identifier and Stream Sequence Number * * If an endpoint receive a DATA chunk with an invalid stream * identifier, it shall acknowledge the reception of the DATA chunk * following the normal procedure, immediately send an ERROR chunk * with cause set to "Invalid Stream Identifier" (See Section 3.3.10) * and discard the DATA chunk. */ sid = ntohs(data_hdr->stream); if (sid >= asoc->c.sinit_max_instreams) { /* Mark tsn as received even though we drop it */ sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_TSN, SCTP_U32(tsn)); err = sctp_make_op_error(asoc, chunk, SCTP_ERROR_INV_STRM, &data_hdr->stream, sizeof(data_hdr->stream), sizeof(u16)); if (err) sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(err)); return SCTP_IERROR_BAD_STREAM; } /* Check to see if the SSN is possible for this TSN. * The biggest gap we can record is 4K wide. Since SSNs wrap * at an unsigned short, there is no way that an SSN can * wrap and for a valid TSN. We can simply check if the current * SSN is smaller then the next expected one. If it is, it wrapped * and is invalid. */ ssn = ntohs(data_hdr->ssn); if (ordered && SSN_lt(ssn, sctp_ssn_peek(asoc->stream, in, sid))) return SCTP_IERROR_PROTO_VIOLATION; /* Send the data up to the user. Note: Schedule the * SCTP_CMD_CHUNK_ULP cmd before the SCTP_CMD_GEN_SACK, as the SACK * chunk needs the updated rwnd. */ sctp_add_cmd_sf(commands, deliver, SCTP_CHUNK(chunk)); return SCTP_IERROR_NO_ERROR; }