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
  18 void sem_init(void);
  19 void msg_init(void);
  20 void shm_init(void);
  21
  22 struct ipc_namespace;
  23
  24 #ifdef CONFIG_POSIX_MQUEUE
  25 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  26 extern void mq_put_mnt(struct ipc_namespace *ns);
  27 #else
  28 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  29 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
  30 #endif
  31
  32 #ifdef CONFIG_SYSVIPC
  33 void sem_init_ns(struct ipc_namespace *ns);
  34 void msg_init_ns(struct ipc_namespace *ns);
  35 void shm_init_ns(struct ipc_namespace *ns);
  36
  37 void sem_exit_ns(struct ipc_namespace *ns);
  38 void msg_exit_ns(struct ipc_namespace *ns);
  39 void shm_exit_ns(struct ipc_namespace *ns);
  40 #else
  41 static inline void sem_init_ns(struct ipc_namespace *ns) { }
  42 static inline void msg_init_ns(struct ipc_namespace *ns) { }
  43 static inline void shm_init_ns(struct ipc_namespace *ns) { }
  44
  45 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  46 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  47 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  48 #endif
  49
  50 struct 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  */
  61 struct 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  */
  80 struct 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
  86 struct seq_file;
  87 struct ipc_ids;
  88
  89 void ipc_init_ids(struct ipc_ids *);
  90 #ifdef CONFIG_PROC_FS
  91 void __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 */
 106 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 107
 108 /* must be called with ids->rwsem acquired for reading */
 109 int ipc_get_maxid(struct ipc_ids *);
 110
 111 /* must be called with both locks acquired. */
 112 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 113
 114 /* must be called with ipcp locked */
 115 int 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  */
 120 void *ipc_alloc(int size);
 121 void ipc_free(void *ptr, int size);
 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  */
 129 void *ipc_rcu_alloc(int size);
 130 int ipc_rcu_getref(void *ptr);
 131 void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head));
 132 void ipc_rcu_free(struct rcu_head *head);
 133
 134 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 135 struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id);
 136
 137 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 138 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 139 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 140 struct 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
 148 int ipc_parse_version(int *cmd);
 149 #endif
 150
 151 extern void free_msg(struct msg_msg *msg);
 152 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 153 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 154 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 155
 156 extern void recompute_msgmni(struct ipc_namespace *);
 157
 158 static inline int ipc_buildid(int id, int seq)
 159 {
 160         return SEQ_MULTIPLIER * seq + id;
 161 }
 162
 163 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 164 {
 165         return uid / SEQ_MULTIPLIER != ipcp->seq;
 166 }
 167
 168 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 169 {
 170         spin_lock(&perm->lock);
 171 }
 172
 173 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 174 {
 175         spin_unlock(&perm->lock);
 176 }
 177
 178 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 179 {
 180         assert_spin_locked(&perm->lock);
 181 }
 182
 183 static 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  */
 197 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 198 {
 199         return !perm->deleted;
 200 }
 201
 202 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 203 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 204                         const struct ipc_ops *ops, struct ipc_params *params);
 205 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 206                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 207 #endif