ipc/util.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * linux/ipc/util.h
   4  * Copyright (C) 1999 Christoph Rohland
   5  *
   6  * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
   7  * namespaces support.      2006 OpenVZ, SWsoft Inc.
   8  *                               Pavel Emelianov <xemul@openvz.org>
   9  */
  10
  11 #ifndef _IPC_UTIL_H
  12 #define _IPC_UTIL_H
  13
  14 #include <linux/unistd.h>
  15 #include <linux/err.h>
  16 #include <linux/ipc_namespace.h>
  17
  18 #define SEQ_MULTIPLIER  (IPCMNI)
  19
  20 int sem_init(void);
  21 int msg_init(void);
  22 void shm_init(void);
  23
  24 struct ipc_namespace;
  25
  26 #ifdef CONFIG_POSIX_MQUEUE
  27 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  28 extern void mq_put_mnt(struct ipc_namespace *ns);
  29 #else
  30 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  31 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
  32 #endif
  33
  34 #ifdef CONFIG_SYSVIPC
  35 int sem_init_ns(struct ipc_namespace *ns);
  36 int msg_init_ns(struct ipc_namespace *ns);
  37 int shm_init_ns(struct ipc_namespace *ns);
  38
  39 void sem_exit_ns(struct ipc_namespace *ns);
  40 void msg_exit_ns(struct ipc_namespace *ns);
  41 void shm_exit_ns(struct ipc_namespace *ns);
  42 #else
  43 static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
  44 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
  45 static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
  46
  47 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  48 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  49 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  50 #endif
  51
  52 /*
  53  * Structure that holds the parameters needed by the ipc operations
  54  * (see after)
  55  */
  56 struct ipc_params {
  57         key_t key;
  58         int flg;
  59         union {
  60                 size_t size;    /* for shared memories */
  61                 int nsems;      /* for semaphores */
  62         } u;                    /* holds the getnew() specific param */
  63 };
  64
  65 /*
  66  * Structure that holds some ipc operations. This structure is used to unify
  67  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  68  *      . routine to call to create a new ipc object. Can be one of newque,
  69  *        newary, newseg
  70  *      . routine to call to check permissions for a new ipc object.
  71  *        Can be one of security_msg_associate, security_sem_associate,
  72  *        security_shm_associate
  73  *      . routine to call for an extra check if needed
  74  */
  75 struct ipc_ops {
  76         int (*getnew)(struct ipc_namespace *, struct ipc_params *);
  77         int (*associate)(struct kern_ipc_perm *, int);
  78         int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
  79 };
  80
  81 struct seq_file;
  82 struct ipc_ids;
  83
  84 int ipc_init_ids(struct ipc_ids *);
  85 #ifdef CONFIG_PROC_FS
  86 void __init ipc_init_proc_interface(const char *path, const char *header,
  87                 int ids, int (*show)(struct seq_file *, void *));
  88 #else
  89 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  90 #endif
  91
  92 #define IPC_SEM_IDS     0
  93 #define IPC_MSG_IDS     1
  94 #define IPC_SHM_IDS     2
  95
  96 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
  97 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
  98 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
  99
 100 /* must be called with ids->rwsem acquired for writing */
 101 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 102
 103 /* must be called with both locks acquired. */
 104 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 105
 106 /* must be called with both locks acquired. */
 107 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
 108
 109 /* must be called with ipcp locked */
 110 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 111
 112 /**
 113  * ipc_get_maxid - get the last assigned id
 114  * @ids: ipc identifier set
 115  *
 116  * Called with ipc_ids.rwsem held for reading.
 117  */
 118 static inline int ipc_get_maxid(struct ipc_ids *ids)
 119 {
 120         if (ids->in_use == 0)
 121                 return -1;
 122
 123         if (ids->in_use == IPCMNI)
 124                 return IPCMNI - 1;
 125
 126         return ids->max_id;
 127 }
 128
 129 /*
 130  * For allocation that need to be freed by RCU.
 131  * Objects are reference counted, they start with reference count 1.
 132  * getref increases the refcount, the putref call that reduces the recount
 133  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 134  *
 135  * refcount is initialized by ipc_addid(), before that point call_rcu()
 136  * must be used.
 137  */
 138 int ipc_rcu_getref(struct kern_ipc_perm *ptr);
 139 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 140                         void (*func)(struct rcu_head *head));
 141
 142 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 143 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 144
 145 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 146 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 147 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 148 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 149                                              struct ipc_ids *ids, int id, int cmd,
 150                                              struct ipc64_perm *perm, int extra_perm);
 151
 152 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 153 /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 154 # define ipc_parse_version(cmd) IPC_64
 155 #else
 156 int ipc_parse_version(int *cmd);
 157 #endif
 158
 159 extern void free_msg(struct msg_msg *msg);
 160 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 161 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 162 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 163
 164 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 165 {
 166         return uid / SEQ_MULTIPLIER != ipcp->seq;
 167 }
 168
 169 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 170 {
 171         spin_lock(&perm->lock);
 172 }
 173
 174 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 175 {
 176         spin_unlock(&perm->lock);
 177 }
 178
 179 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 180 {
 181         assert_spin_locked(&perm->lock);
 182 }
 183
 184 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 185 {
 186         ipc_unlock_object(perm);
 187         rcu_read_unlock();
 188 }
 189
 190 /*
 191  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 192  * where the respective ipc_ids.rwsem is not being held down.
 193  * Checks whether the ipc object is still around or if it's gone already, as
 194  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 195  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 196  * checkpoint case at sys_semtimedop() as noted in code commentary.
 197  */
 198 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 199 {
 200         return !perm->deleted;
 201 }
 202
 203 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 204 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 205                         const struct ipc_ops *ops, struct ipc_params *params);
 206 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 207                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 208
 209 #ifdef CONFIG_COMPAT
 210 #include <linux/compat.h>
 211 struct compat_ipc_perm {
 212         key_t key;
 213         __compat_uid_t uid;
 214         __compat_gid_t gid;
 215         __compat_uid_t cuid;
 216         __compat_gid_t cgid;
 217         compat_mode_t mode;
 218         unsigned short seq;
 219 };
 220
 221 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
 222 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
 223 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
 224 int get_compat_ipc64_perm(struct ipc64_perm *,
 225                           struct compat_ipc64_perm __user *);
 226
 227 static inline int compat_ipc_parse_version(int *cmd)
 228 {
 229 #ifdef  CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 230         int version = *cmd & IPC_64;
 231         *cmd &= ~IPC_64;
 232         return version;
 233 #else
 234         return IPC_64;
 235 #endif
 236 }
 237 #endif
 238 #endif