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
  17 void sem_init (void);
  18 void msg_init (void);
  19 void shm_init (void);
  20
  21 struct ipc_namespace;
  22
  23 #ifdef CONFIG_POSIX_MQUEUE
  24 void mq_exit_ns(struct ipc_namespace *ns);
  25 #else
  26 static inline void mq_exit_ns(struct ipc_namespace *ns) { }
  27 #endif
  28
  29 #ifdef CONFIG_SYSVIPC
  30 void sem_init_ns(struct ipc_namespace *ns);
  31 void msg_init_ns(struct ipc_namespace *ns);
  32 void shm_init_ns(struct ipc_namespace *ns);
  33
  34 void sem_exit_ns(struct ipc_namespace *ns);
  35 void msg_exit_ns(struct ipc_namespace *ns);
  36 void shm_exit_ns(struct ipc_namespace *ns);
  37 #else
  38 static inline void sem_init_ns(struct ipc_namespace *ns) { }
  39 static inline void msg_init_ns(struct ipc_namespace *ns) { }
  40 static inline void shm_init_ns(struct ipc_namespace *ns) { }
  41
  42 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  43 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  44 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  45 #endif
  46
  47 /*
  48  * Structure that holds the parameters needed by the ipc operations
  49  * (see after)
  50  */
  51 struct ipc_params {
  52         key_t key;
  53         int flg;
  54         union {
  55                 size_t size;    /* for shared memories */
  56                 int nsems;      /* for semaphores */
  57         } u;                    /* holds the getnew() specific param */
  58 };
  59
  60 /*
  61  * Structure that holds some ipc operations. This structure is used to unify
  62  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  63  *      . routine to call to create a new ipc object. Can be one of newque,
  64  *        newary, newseg
  65  *      . routine to call to check permissions for a new ipc object.
  66  *        Can be one of security_msg_associate, security_sem_associate,
  67  *        security_shm_associate
  68  *      . routine to call for an extra check if needed
  69  */
  70 struct ipc_ops {
  71         int (*getnew) (struct ipc_namespace *, struct ipc_params *);
  72         int (*associate) (struct kern_ipc_perm *, int);
  73         int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
  74 };
  75
  76 struct seq_file;
  77 struct ipc_ids;
  78
  79 void ipc_init_ids(struct ipc_ids *);
  80 #ifdef CONFIG_PROC_FS
  81 void __init ipc_init_proc_interface(const char *path, const char *header,
  82                 int ids, int (*show)(struct seq_file *, void *));
  83 #else
  84 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  85 #endif
  86
  87 #define IPC_SEM_IDS     0
  88 #define IPC_MSG_IDS     1
  89 #define IPC_SHM_IDS     2
  90
  91 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  92
  93 /* must be called with ids->rw_mutex acquired for writing */
  94 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  95
  96 /* must be called with ids->rw_mutex acquired for reading */
  97 int ipc_get_maxid(struct ipc_ids *);
  98
  99 /* must be called with both locks acquired. */
 100 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 101
 102 /* must be called with ipcp locked */
 103 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
 104
 105 /* for rare, potentially huge allocations.
 106  * both function can sleep
 107  */
 108 void* ipc_alloc(int size);
 109 void ipc_free(void* ptr, int size);
 110
 111 /*
 112  * For allocation that need to be freed by RCU.
 113  * Objects are reference counted, they start with reference count 1.
 114  * getref increases the refcount, the putref call that reduces the recount
 115  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 116  */
 117 void* ipc_rcu_alloc(int size);
 118 void ipc_rcu_getref(void *ptr);
 119 void ipc_rcu_putref(void *ptr);
 120
 121 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 122
 123 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 124 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 125 void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 126 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
 127                                       struct ipc64_perm *perm, int extra_perm);
 128
 129 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 130   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 131 # define ipc_parse_version(cmd) IPC_64
 132 #else
 133 int ipc_parse_version (int *cmd);
 134 #endif
 135
 136 extern void free_msg(struct msg_msg *msg);
 137 extern struct msg_msg *load_msg(const void __user *src, int len);
 138 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 139
 140 extern void recompute_msgmni(struct ipc_namespace *);
 141
 142 static inline int ipc_buildid(int id, int seq)
 143 {
 144         return SEQ_MULTIPLIER * seq + id;
 145 }
 146
 147 /*
 148  * Must be called with ipcp locked
 149  */
 150 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 151 {
 152         if (uid / SEQ_MULTIPLIER != ipcp->seq)
 153                 return 1;
 154         return 0;
 155 }
 156
 157 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 158 {
 159         rcu_read_lock();
 160         spin_lock(&perm->lock);
 161 }
 162
 163 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 164 {
 165         spin_unlock(&perm->lock);
 166         rcu_read_unlock();
 167 }
 168
 169 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
 170 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 171                         struct ipc_ops *ops, struct ipc_params *params);
 172
 173 #endif