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 void sem_init_ns(struct ipc_namespace *ns);
  24 void msg_init_ns(struct ipc_namespace *ns);
  25 void shm_init_ns(struct ipc_namespace *ns);
  26
  27 void sem_exit_ns(struct ipc_namespace *ns);
  28 void msg_exit_ns(struct ipc_namespace *ns);
  29 void shm_exit_ns(struct ipc_namespace *ns);
  30
  31 /*
  32  * Structure that holds the parameters needed by the ipc operations
  33  * (see after)
  34  */
  35 struct 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  */
  54 struct 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
  60 struct seq_file;
  61 struct ipc_ids;
  62
  63 void ipc_init_ids(struct ipc_ids *);
  64 #ifdef CONFIG_PROC_FS
  65 void __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 */
  78 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  79
  80 /* must be called with ids->rw_mutex acquired for reading */
  81 int ipc_get_maxid(struct ipc_ids *);
  82
  83 /* must be called with both locks acquired. */
  84 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
  85
  86 /* must be called with ipcp locked */
  87 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
  88
  89 /* for rare, potentially huge allocations.
  90  * both function can sleep
  91  */
  92 void* ipc_alloc(int size);
  93 void 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  */
 101 void* ipc_rcu_alloc(int size);
 102 void ipc_rcu_getref(void *ptr);
 103 void ipc_rcu_putref(void *ptr);
 104
 105 /*
 106  * ipc_lock_down: called with rw_mutex held
 107  * ipc_lock: called without that lock held
 108  */
 109 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 110 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 111
 112 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 113 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 114 void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 115 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
 116                                       struct ipc64_perm *perm, int extra_perm);
 117
 118 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 119   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 120 # define ipc_parse_version(cmd) IPC_64
 121 #else
 122 int ipc_parse_version (int *cmd);
 123 #endif
 124
 125 extern void free_msg(struct msg_msg *msg);
 126 extern struct msg_msg *load_msg(const void __user *src, int len);
 127 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 128
 129 extern void recompute_msgmni(struct ipc_namespace *);
 130
 131 static inline int ipc_buildid(int id, int seq)
 132 {
 133         return SEQ_MULTIPLIER * seq + id;
 134 }
 135
 136 /*
 137  * Must be called with ipcp locked
 138  */
 139 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 140 {
 141         if (uid / SEQ_MULTIPLIER != ipcp->seq)
 142                 return 1;
 143         return 0;
 144 }
 145
 146 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 147 {
 148         rcu_read_lock();
 149         spin_lock(&perm->lock);
 150 }
 151
 152 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 153 {
 154         spin_unlock(&perm->lock);
 155         rcu_read_unlock();
 156 }
 157
 158 struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id);
 159 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
 160 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 161                         struct ipc_ops *ops, struct ipc_params *params);
 162
 163 #endif