blob: 60ddccca464dd2a9f54ebe50401cdd009b3084ca [file] [log] [blame]
* linux/ipc/util.h
* Copyright (C) 1999 Christoph Rohland
* ipc helper functions (c) 1999 Manfred Spraul <>
* namespaces support. 2006 OpenVZ, SWsoft Inc.
* Pavel Emelianov <>
#ifndef _IPC_UTIL_H
#define _IPC_UTIL_H
#include <linux/unistd.h>
#include <linux/err.h>
void sem_init(void);
void msg_init(void);
void shm_init(void);
struct ipc_namespace;
extern void mq_clear_sbinfo(struct ipc_namespace *ns);
extern void mq_put_mnt(struct ipc_namespace *ns);
static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
static inline void mq_put_mnt(struct ipc_namespace *ns) { }
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);
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) { }
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 *);
void __init ipc_init_proc_interface(const char *path, const char *header,
int ids, int (*show)(struct seq_file *, void *));
#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
#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)
/* 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);
/* On IA-64, we always use the "64-bit version" of the IPC structures. */
# define ipc_parse_version(cmd) IPC_64
int ipc_parse_version(int *cmd);
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);
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)
static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
static inline void ipc_unlock(struct kern_ipc_perm *perm)
* 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 *));