LXR linux/ipc/util.h

   1/*
   2 * linux/ipc/util.h
   3 * Copyright (C) 1999 Christoph Rohland
   4 *
   5 * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
   6 * namespaces support.      2006 OpenVZ, SWsoft Inc.
   7 *                               Pavel Emelianov <xemul@openvz.org>
   8 */
   9
  10#ifndef _IPC_UTIL_H
  11#define _IPC_UTIL_H
  12
  13#include <linux/unistd.h>
  14#include <linux/err.h>
  15
  16#define SEQ_MULTIPLIER  (IPCMNI)
  17
  18void sem_init(void);
  19void msg_init(void);
  20void shm_init(void);
  21
  22struct ipc_namespace;
  23
  24#ifdef CONFIG_POSIX_MQUEUE
  25extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  26extern void mq_put_mnt(struct ipc_namespace *ns);
  27#else
  28static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  29static inline void mq_put_mnt(struct ipc_namespace *ns) { }
  30#endif
  31
  32#ifdef CONFIG_SYSVIPC
  33void sem_init_ns(struct ipc_namespace *ns);
  34void msg_init_ns(struct ipc_namespace *ns);
  35void shm_init_ns(struct ipc_namespace *ns);
  36
  37void sem_exit_ns(struct ipc_namespace *ns);
  38void msg_exit_ns(struct ipc_namespace *ns);
  39void shm_exit_ns(struct ipc_namespace *ns);
  40#else
  41static inline void sem_init_ns(struct ipc_namespace *ns) { }
  42static inline void msg_init_ns(struct ipc_namespace *ns) { }
  43static inline void shm_init_ns(struct ipc_namespace *ns) { }
  44
  45static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  46static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  47static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  48#endif
  49
  50struct ipc_rcu {
  51        struct rcu_head rcu;
  52        atomic_t refcount;
  53} ____cacheline_aligned_in_smp;
  54
  55#define ipc_rcu_to_struct(p)  ((void *)(p+1))
  56
  57/*
  58 * Structure that holds the parameters needed by the ipc operations
  59 * (see after)
  60 */
  61struct ipc_params {
  62        key_t key;
  63        int flg;
  64        union {
  65                size_t size;    /* for shared memories */
  66                int nsems;      /* for semaphores */
  67        } u;                    /* holds the getnew() specific param */
  68};
  69
  70/*
  71 * Structure that holds some ipc operations. This structure is used to unify
  72 * the calls to sys_msgget(), sys_semget(), sys_shmget()
  73 *      . routine to call to create a new ipc object. Can be one of newque,
  74 *        newary, newseg
  75 *      . routine to call to check permissions for a new ipc object.
  76 *        Can be one of security_msg_associate, security_sem_associate,
  77 *        security_shm_associate
  78 *      . routine to call for an extra check if needed
  79 */
  80struct ipc_ops {
  81        int (*getnew)(struct ipc_namespace *, struct ipc_params *);
  82        int (*associate)(struct kern_ipc_perm *, int);
  83        int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
  84};
  85
  86struct seq_file;
  87struct ipc_ids;
  88
  89void ipc_init_ids(struct ipc_ids *);
  90#ifdef CONFIG_PROC_FS
  91void __init ipc_init_proc_interface(const char *path, const char *header,
  92                int ids, int (*show)(struct seq_file *, void *));
  93#else
  94#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  95#endif
  96
  97#define IPC_SEM_IDS     0
  98#define IPC_MSG_IDS     1
  99#define IPC_SHM_IDS     2
 100
 101#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
 102#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
 103#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
 104
 105/* must be called with ids->rwsem acquired for writing */
 106int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 107
 108/* must be called with ids->rwsem acquired for reading */
 109int ipc_get_maxid(struct ipc_ids *);
 110
 111/* must be called with both locks acquired. */
 112void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 113
 114/* must be called with ipcp locked */
 115int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 116
 117/* for rare, potentially huge allocations.
 118 * both function can sleep
 119 */
 120void *ipc_alloc(int size);
 121void ipc_free(void *ptr);
 122
 123/*
 124 * For allocation that need to be freed by RCU.
 125 * Objects are reference counted, they start with reference count 1.
 126 * getref increases the refcount, the putref call that reduces the recount
 127 * to 0 schedules the rcu destruction. Caller must guarantee locking.
 128 */
 129void *ipc_rcu_alloc(int size);
 130int ipc_rcu_getref(void *ptr);
 131void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head));
 132void ipc_rcu_free(struct rcu_head *head);
 133
 134struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 135struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 136
 137void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 138void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 139int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 140struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 141                                             struct ipc_ids *ids, int id, int cmd,
 142                                             struct ipc64_perm *perm, int extra_perm);
 143
 144#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 145/* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 146# define ipc_parse_version(cmd) IPC_64
 147#else
 148int ipc_parse_version(int *cmd);
 149#endif
 150
 151extern void free_msg(struct msg_msg *msg);
 152extern struct msg_msg *load_msg(const void __user *src, size_t len);
 153extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 154extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 155
 156extern void recompute_msgmni(struct ipc_namespace *);
 157
 158static inline int ipc_buildid(int id, int seq)
 159{
 160        return SEQ_MULTIPLIER * seq + id;
 161}
 162
 163static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 164{
 165        return uid / SEQ_MULTIPLIER != ipcp->seq;
 166}
 167
 168static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 169{
 170        spin_lock(&perm->lock);
 171}
 172
 173static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 174{
 175        spin_unlock(&perm->lock);
 176}
 177
 178static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 179{
 180        assert_spin_locked(&perm->lock);
 181}
 182
 183static inline void ipc_unlock(struct kern_ipc_perm *perm)
 184{
 185        ipc_unlock_object(perm);
 186        rcu_read_unlock();
 187}
 188
 189/*
 190 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 191 * where the respective ipc_ids.rwsem is not being held down.
 192 * Checks whether the ipc object is still around or if it's gone already, as
 193 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 194 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 195 * checkpoint case at sys_semtimedop() as noted in code commentary.
 196 */
 197static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 198{
 199        return !perm->deleted;
 200}
 201
 202struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 203int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 204                        const struct ipc_ops *ops, struct ipc_params *params);
 205void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 206                void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 207#endif
 208