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/err.h>
  14
  15#define SEQ_MULTIPLIER  (IPCMNI)
  16
  17void sem_init (void);
  18void msg_init (void);
  19void shm_init (void);
  20
  21struct ipc_namespace;
  22
  23void sem_init_ns(struct ipc_namespace *ns);
  24void msg_init_ns(struct ipc_namespace *ns);
  25void shm_init_ns(struct ipc_namespace *ns);
  26
  27void sem_exit_ns(struct ipc_namespace *ns);
  28void msg_exit_ns(struct ipc_namespace *ns);
  29void shm_exit_ns(struct ipc_namespace *ns);
  30
  31/*
  32 * Structure that holds the parameters needed by the ipc operations
  33 * (see after)
  34 */
  35struct ipc_params {
  36        key_t key;
  37        int flg;
  38        union {
  39                size_t size;    /* for shared memories */
  40                int nsems;      /* for semaphores */
  41        } u;                    /* holds the getnew() specific param */
  42};
  43
  44/*
  45 * Structure that holds some ipc operations. This structure is used to unify
  46 * the calls to sys_msgget(), sys_semget(), sys_shmget()
  47 *      . routine to call to create a new ipc object. Can be one of newque,
  48 *        newary, newseg
  49 *      . routine to call to check permissions for a new ipc object.
  50 *        Can be one of security_msg_associate, security_sem_associate,
  51 *        security_shm_associate
  52 *      . routine to call for an extra check if needed
  53 */
  54struct ipc_ops {
  55        int (*getnew) (struct ipc_namespace *, struct ipc_params *);
  56        int (*associate) (struct kern_ipc_perm *, int);
  57        int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
  58};
  59
  60struct seq_file;
  61struct ipc_ids;
  62
  63void ipc_init_ids(struct ipc_ids *);
  64#ifdef CONFIG_PROC_FS
  65void __init ipc_init_proc_interface(const char *path, const char *header,
  66                int ids, int (*show)(struct seq_file *, void *));
  67#else
  68#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  69#endif
  70
  71#define IPC_SEM_IDS     0
  72#define IPC_MSG_IDS     1
  73#define IPC_SHM_IDS     2
  74
  75#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  76
  77/* must be called with ids->rw_mutex acquired for writing */
  78int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  79
  80/* must be called with ids->rw_mutex acquired for reading */
  81int ipc_get_maxid(struct ipc_ids *);
  82
  83/* must be called with both locks acquired. */
  84void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
  85
  86/* must be called with ipcp locked */
  87int ipcperms(struct kern_ipc_perm *ipcp, short flg);
  88
  89/* for rare, potentially huge allocations.
  90 * both function can sleep
  91 */
  92void* ipc_alloc(int size);
  93void ipc_free(void* ptr, int size);
  94
  95/*
  96 * For allocation that need to be freed by RCU.
  97 * Objects are reference counted, they start with reference count 1.
  98 * getref increases the refcount, the putref call that reduces the recount
  99 * to 0 schedules the rcu destruction. Caller must guarantee locking.
 100 */
 101void* ipc_rcu_alloc(int size);
 102void ipc_rcu_getref(void *ptr);
 103void ipc_rcu_putref(void *ptr);
 104
 105struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 106
 107void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 108void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 109void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 110struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
 111                                      struct ipc64_perm *perm, int extra_perm);
 112
 113#if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 114  /* On IA-64, we always use the "64-bit version" of the IPC structures.  */ 
 115# define ipc_parse_version(cmd) IPC_64
 116#else
 117int ipc_parse_version (int *cmd);
 118#endif
 119
 120extern void free_msg(struct msg_msg *msg);
 121extern struct msg_msg *load_msg(const void __user *src, int len);
 122extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 123
 124extern void recompute_msgmni(struct ipc_namespace *);
 125
 126static inline int ipc_buildid(int id, int seq)
 127{
 128        return SEQ_MULTIPLIER * seq + id;
 129}
 130
 131/*
 132 * Must be called with ipcp locked
 133 */
 134static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 135{
 136        if (uid / SEQ_MULTIPLIER != ipcp->seq)
 137                return 1;
 138        return 0;
 139}
 140
 141static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 142{
 143        rcu_read_lock();
 144        spin_lock(&perm->lock);
 145}
 146
 147static inline void ipc_unlock(struct kern_ipc_perm *perm)
 148{
 149        spin_unlock(&perm->lock);
 150        rcu_read_unlock();
 151}
 152
 153struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
 154int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 155                        struct ipc_ops *ops, struct ipc_params *params);
 156
 157#endif
 158