/* * linux/ipc/util.h * Copyright (C) 1999 Christoph Rohland * * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com> * namespaces support. 2006 OpenVZ, SWsoft Inc. * Pavel Emelianov <xemul@openvz.org> */ #ifndef _IPC_UTIL_H #define _IPC_UTIL_H #include <linux/unistd.h> #include <linux/err.h> #define SEQ_MULTIPLIER (IPCMNI) void sem_init(void); void msg_init(void); void shm_init(void); struct ipc_namespace; #ifdef CONFIG_POSIX_MQUEUE extern void mq_clear_sbinfo(struct ipc_namespace *ns); extern void mq_put_mnt(struct ipc_namespace *ns); #else static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { } static inline void mq_put_mnt(struct ipc_namespace *ns) { } #endif #ifdef CONFIG_SYSVIPC void sem_init_ns(struct ipc_namespace *ns); void msg_init_ns(struct ipc_namespace *ns); void shm_init_ns(struct ipc_namespace *ns); void sem_exit_ns(struct ipc_namespace *ns); void msg_exit_ns(struct ipc_namespace *ns); void shm_exit_ns(struct ipc_namespace *ns); #else static inline void sem_init_ns(struct ipc_namespace *ns) { } static inline void msg_init_ns(struct ipc_namespace *ns) { } static inline void shm_init_ns(struct ipc_namespace *ns) { } static inline void sem_exit_ns(struct ipc_namespace *ns) { } static inline void msg_exit_ns(struct ipc_namespace *ns) { } static inline void shm_exit_ns(struct ipc_namespace *ns) { } #endif struct ipc_rcu { struct rcu_head rcu; atomic_t refcount; } ____cacheline_aligned_in_smp; #define ipc_rcu_to_struct(p) ((void *)(p+1)) /* * Structure that holds the parameters needed by the ipc operations * (see after) */ struct ipc_params { key_t key; int flg; union { size_t size; /* for shared memories */ int nsems; /* for semaphores */ } u; /* holds the getnew() specific param */ }; /* * Structure that holds some ipc operations. This structure is used to unify * the calls to sys_msgget(), sys_semget(), sys_shmget() * . routine to call to create a new ipc object. Can be one of newque, * newary, newseg * . routine to call to check permissions for a new ipc object. * Can be one of security_msg_associate, security_sem_associate, * security_shm_associate * . routine to call for an extra check if needed */ struct ipc_ops { int (*getnew)(struct ipc_namespace *, struct ipc_params *); int (*associate)(struct kern_ipc_perm *, int); int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *); }; struct seq_file; struct ipc_ids; void ipc_init_ids(struct ipc_ids *); #ifdef CONFIG_PROC_FS void __init ipc_init_proc_interface(const char *path, const char *header, int ids, int (*show)(struct seq_file *, void *)); #else #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) #endif #define IPC_SEM_IDS 0 #define IPC_MSG_IDS 1 #define IPC_SHM_IDS 2 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER) #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX) /* must be called with ids->rwsem acquired for writing */ int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); /* must be called with ids->rwsem acquired for reading */ int ipc_get_maxid(struct ipc_ids *); /* must be called with both locks acquired. */ void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); /* must be called with ipcp locked */ int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg); /* for rare, potentially huge allocations. * both function can sleep */ void *ipc_alloc(int size); void ipc_free(void *ptr); /* * For allocation that need to be freed by RCU. * Objects are reference counted, they start with reference count 1. * getref increases the refcount, the putref call that reduces the recount * to 0 schedules the rcu destruction. Caller must guarantee locking. */ void *ipc_rcu_alloc(int size); int ipc_rcu_getref(void *ptr); void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head)); void ipc_rcu_free(struct rcu_head *head); struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id); void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, struct ipc_ids *ids, int id, int cmd, struct ipc64_perm *perm, int extra_perm); #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION /* On IA-64, we always use the "64-bit version" of the IPC structures. */ # define ipc_parse_version(cmd) IPC_64 #else int ipc_parse_version(int *cmd); #endif extern void free_msg(struct msg_msg *msg); extern struct msg_msg *load_msg(const void __user *src, size_t len); extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst); extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len); extern void recompute_msgmni(struct ipc_namespace *); static inline int ipc_buildid(int id, int seq) { return SEQ_MULTIPLIER * seq + id; } static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) { return uid / SEQ_MULTIPLIER != ipcp->seq; } static inline void ipc_lock_object(struct kern_ipc_perm *perm) { spin_lock(&perm->lock); } static inline void ipc_unlock_object(struct kern_ipc_perm *perm) { spin_unlock(&perm->lock); } static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm) { assert_spin_locked(&perm->lock); } static inline void ipc_unlock(struct kern_ipc_perm *perm) { ipc_unlock_object(perm); rcu_read_unlock(); } /* * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths * where the respective ipc_ids.rwsem is not being held down. * Checks whether the ipc object is still around or if it's gone already, as * ipc_rmid() may have already freed the ID while the ipc lock was spinning. * Needs to be called with kern_ipc_perm.lock held -- exception made for one * checkpoint case at sys_semtimedop() as noted in code commentary. */ static inline bool ipc_valid_object(struct kern_ipc_perm *perm) { return !perm->deleted; } struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, const struct ipc_ops *ops, struct ipc_params *params); void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)); #endif