/* Copyright (c) 2016 Facebook * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. */ #define KBUILD_MODNAME "foo" #include <linux/if_ether.h> #include <linux/ip.h> #include <linux/ipv6.h> #include <linux/in.h> #include <linux/tcp.h> #include <linux/udp.h> #include <uapi/linux/bpf.h> #include <net/ip.h> #include "bpf_helpers.h" #define DEFAULT_PKTGEN_UDP_PORT 9 #define DEBUG 0 static int tcp(void *data, uint64_t tp_off, void *data_end) { struct tcphdr *tcp = data + tp_off; if (tcp + 1 > data_end) return 0; if (tcp->dest == htons(80) || tcp->source == htons(80)) return TC_ACT_SHOT; return 0; } static int udp(void *data, uint64_t tp_off, void *data_end) { struct udphdr *udp = data + tp_off; if (udp + 1 > data_end) return 0; if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) || udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) { if (DEBUG) { char fmt[] = "udp port 9 indeed\n"; bpf_trace_printk(fmt, sizeof(fmt)); } return TC_ACT_SHOT; } return 0; } static int parse_ipv4(void *data, uint64_t nh_off, void *data_end) { struct iphdr *iph; uint64_t ihl_len; iph = data + nh_off; if (iph + 1 > data_end) return 0; if (ip_is_fragment(iph)) return 0; ihl_len = iph->ihl * 4; if (iph->protocol == IPPROTO_IPIP) { iph = data + nh_off + ihl_len; if (iph + 1 > data_end) return 0; ihl_len += iph->ihl * 4; } if (iph->protocol == IPPROTO_TCP) return tcp(data, nh_off + ihl_len, data_end); else if (iph->protocol == IPPROTO_UDP) return udp(data, nh_off + ihl_len, data_end); return 0; } static int parse_ipv6(void *data, uint64_t nh_off, void *data_end) { struct ipv6hdr *ip6h; struct iphdr *iph; uint64_t ihl_len = sizeof(struct ipv6hdr); uint64_t nexthdr; ip6h = data + nh_off; if (ip6h + 1 > data_end) return 0; nexthdr = ip6h->nexthdr; if (nexthdr == IPPROTO_IPIP) { iph = data + nh_off + ihl_len; if (iph + 1 > data_end) return 0; ihl_len += iph->ihl * 4; nexthdr = iph->protocol; } else if (nexthdr == IPPROTO_IPV6) { ip6h = data + nh_off + ihl_len; if (ip6h + 1 > data_end) return 0; ihl_len += sizeof(struct ipv6hdr); nexthdr = ip6h->nexthdr; } if (nexthdr == IPPROTO_TCP) return tcp(data, nh_off + ihl_len, data_end); else if (nexthdr == IPPROTO_UDP) return udp(data, nh_off + ihl_len, data_end); return 0; } struct vlan_hdr { uint16_t h_vlan_TCI; uint16_t h_vlan_encapsulated_proto; }; SEC("varlen") int handle_ingress(struct __sk_buff *skb) { void *data = (void *)(long)skb->data; struct ethhdr *eth = data; void *data_end = (void *)(long)skb->data_end; uint64_t h_proto, nh_off; nh_off = sizeof(*eth); if (data + nh_off > data_end) return 0; h_proto = eth->h_proto; if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { struct vlan_hdr *vhdr; vhdr = data + nh_off; nh_off += sizeof(struct vlan_hdr); if (data + nh_off > data_end) return 0; h_proto = vhdr->h_vlan_encapsulated_proto; } if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { struct vlan_hdr *vhdr; vhdr = data + nh_off; nh_off += sizeof(struct vlan_hdr); if (data + nh_off > data_end) return 0; h_proto = vhdr->h_vlan_encapsulated_proto; } if (h_proto == htons(ETH_P_IP)) return parse_ipv4(data, nh_off, data_end); else if (h_proto == htons(ETH_P_IPV6)) return parse_ipv6(data, nh_off, data_end); return 0; } char _license[] SEC("license") = "GPL";