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 /*
  51  * Structure that holds the parameters needed by the ipc operations
  52  * (see after)
  53  */
  54 struct ipc_params {
  55         key_t key;
  56         int flg;
  57         union {
  58                 size_t size;    /* for shared memories */
  59                 int nsems;      /* for semaphores */
  60         } u;                    /* holds the getnew() specific param */
  61 };
  62
  63 /*
  64  * Structure that holds some ipc operations. This structure is used to unify
  65  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  66  *      . routine to call to create a new ipc object. Can be one of newque,
  67  *        newary, newseg
  68  *      . routine to call to check permissions for a new ipc object.
  69  *        Can be one of security_msg_associate, security_sem_associate,
  70  *        security_shm_associate
  71  *      . routine to call for an extra check if needed
  72  */
  73 struct ipc_ops {
  74         int (*getnew)(struct ipc_namespace *, struct ipc_params *);
  75         int (*associate)(struct kern_ipc_perm *, int);
  76         int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
  77 };
  78
  79 struct seq_file;
  80 struct ipc_ids;
  81
  82 void ipc_init_ids(struct ipc_ids *);
  83 #ifdef CONFIG_PROC_FS
  84 void __init ipc_init_proc_interface(const char *path, const char *header,
  85                 int ids, int (*show)(struct seq_file *, void *));
  86 #else
  87 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  88 #endif
  89
  90 #define IPC_SEM_IDS     0
  91 #define IPC_MSG_IDS     1
  92 #define IPC_SHM_IDS     2
  93
  94 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  95 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
  96 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
  97
  98 /* must be called with ids->rwsem acquired for writing */
  99 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 100
 101 /* must be called with ids->rwsem acquired for reading */
 102 int ipc_get_maxid(struct ipc_ids *);
 103
 104 /* must be called with both locks acquired. */
 105 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 106
 107 /* must be called with ipcp locked */
 108 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 109
 110 /*
 111  * For allocation that need to be freed by RCU.
 112  * Objects are reference counted, they start with reference count 1.
 113  * getref increases the refcount, the putref call that reduces the recount
 114  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 115  *
 116  * refcount is initialized by ipc_addid(), before that point call_rcu()
 117  * must be used.
 118  */
 119 int ipc_rcu_getref(struct kern_ipc_perm *ptr);
 120 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 121                         void (*func)(struct rcu_head *head));
 122
 123 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 124 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 125
 126 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 127 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 128 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 129 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 130                                              struct ipc_ids *ids, int id, int cmd,
 131                                              struct ipc64_perm *perm, int extra_perm);
 132
 133 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 134 /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 135 # define ipc_parse_version(cmd) IPC_64
 136 #else
 137 int ipc_parse_version(int *cmd);
 138 #endif
 139
 140 extern void free_msg(struct msg_msg *msg);
 141 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 142 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 143 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 144
 145 static inline int ipc_buildid(int id, int seq)
 146 {
 147         return SEQ_MULTIPLIER * seq + id;
 148 }
 149
 150 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 151 {
 152         return uid / SEQ_MULTIPLIER != ipcp->seq;
 153 }
 154
 155 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 156 {
 157         spin_lock(&perm->lock);
 158 }
 159
 160 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 161 {
 162         spin_unlock(&perm->lock);
 163 }
 164
 165 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 166 {
 167         assert_spin_locked(&perm->lock);
 168 }
 169
 170 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 171 {
 172         ipc_unlock_object(perm);
 173         rcu_read_unlock();
 174 }
 175
 176 /*
 177  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 178  * where the respective ipc_ids.rwsem is not being held down.
 179  * Checks whether the ipc object is still around or if it's gone already, as
 180  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 181  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 182  * checkpoint case at sys_semtimedop() as noted in code commentary.
 183  */
 184 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 185 {
 186         return !perm->deleted;
 187 }
 188
 189 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 190 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 191                         const struct ipc_ops *ops, struct ipc_params *params);
 192 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 193                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 194 #endif