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