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 USHRT_MAX 0xffff
  16 #define SEQ_MULTIPLIER  (IPCMNI)
  17
  18 void sem_init (void);
  19 void msg_init (void);
  20 void shm_init (void);
  21
  22 struct ipc_namespace;
  23
  24 void sem_init_ns(struct ipc_namespace *ns);
  25 void msg_init_ns(struct ipc_namespace *ns);
  26 void shm_init_ns(struct ipc_namespace *ns);
  27
  28 void sem_exit_ns(struct ipc_namespace *ns);
  29 void msg_exit_ns(struct ipc_namespace *ns);
  30 void shm_exit_ns(struct ipc_namespace *ns);
  31
  32 /*
  33  * Structure that holds the parameters needed by the ipc operations
  34  * (see after)
  35  */
  36 struct ipc_params {
  37         key_t key;
  38         int flg;
  39         union {
  40                 size_t size;    /* for shared memories */
  41                 int nsems;      /* for semaphores */
  42         } u;                    /* holds the getnew() specific param */
  43 };
  44
  45 /*
  46  * Structure that holds some ipc operations. This structure is used to unify
  47  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  48  *      . routine to call to create a new ipc object. Can be one of newque,
  49  *        newary, newseg
  50  *      . routine to call to check permissions for a new ipc object.
  51  *        Can be one of security_msg_associate, security_sem_associate,
  52  *        security_shm_associate
  53  *      . routine to call for an extra check if needed
  54  */
  55 struct ipc_ops {
  56         int (*getnew) (struct ipc_namespace *, struct ipc_params *);
  57         int (*associate) (struct kern_ipc_perm *, int);
  58         int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
  59 };
  60
  61 struct seq_file;
  62 struct ipc_ids;
  63
  64 void ipc_init_ids(struct ipc_ids *);
  65 #ifdef CONFIG_PROC_FS
  66 void __init ipc_init_proc_interface(const char *path, const char *header,
  67                 int ids, int (*show)(struct seq_file *, void *));
  68 #else
  69 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  70 #endif
  71
  72 #define IPC_SEM_IDS     0
  73 #define IPC_MSG_IDS     1
  74 #define IPC_SHM_IDS     2
  75
  76 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  77
  78 /* must be called with ids->rw_mutex acquired for writing */
  79 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
  80
  81 /* must be called with ids->rw_mutex acquired for reading */
  82 int ipc_get_maxid(struct ipc_ids *);
  83
  84 /* must be called with both locks acquired. */
  85 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
  86
  87 /* must be called with ipcp locked */
  88 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
  89
  90 /* for rare, potentially huge allocations.
  91  * both function can sleep
  92  */
  93 void* ipc_alloc(int size);
  94 void ipc_free(void* ptr, int size);
  95
  96 /*
  97  * For allocation that need to be freed by RCU.
  98  * Objects are reference counted, they start with reference count 1.
  99  * getref increases the refcount, the putref call that reduces the recount
 100  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 101  */
 102 void* ipc_rcu_alloc(int size);
 103 void ipc_rcu_getref(void *ptr);
 104 void ipc_rcu_putref(void *ptr);
 105
 106 /*
 107  * ipc_lock_down: called with rw_mutex held
 108  * ipc_lock: called without that lock held
 109  */
 110 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 111 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 112
 113 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 114 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 115
 116 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
 117   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 118 # define ipc_parse_version(cmd) IPC_64
 119 #else
 120 int ipc_parse_version (int *cmd);
 121 #endif
 122
 123 extern void free_msg(struct msg_msg *msg);
 124 extern struct msg_msg *load_msg(const void __user *src, int len);
 125 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
 126
 127 static inline int ipc_buildid(int id, int seq)
 128 {
 129         return SEQ_MULTIPLIER * seq + id;
 130 }
 131
 132 /*
 133  * Must be called with ipcp locked
 134  */
 135 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 136 {
 137         if (uid / SEQ_MULTIPLIER != ipcp->seq)
 138                 return 1;
 139         return 0;
 140 }
 141
 142 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 143 {
 144         rcu_read_lock();
 145         spin_lock(&perm->lock);
 146 }
 147
 148 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 149 {
 150         spin_unlock(&perm->lock);
 151         rcu_read_unlock();
 152 }
 153
 154 struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id);
 155 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
 156 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 157                         struct ipc_ops *ops, struct ipc_params *params);
 158
 159 #endif