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 IPCMNI 32768  /* <= MAX_INT limit for ipc arrays (including sysctl changes) */
  19 #define SEQ_MULTIPLIER  (IPCMNI)
  20
  21 int sem_init(void);
  22 int msg_init(void);
  23 void shm_init(void);
  24
  25 struct ipc_namespace;
  26 struct pid_namespace;
  27
  28 #ifdef CONFIG_POSIX_MQUEUE
  29 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  30 extern void mq_put_mnt(struct ipc_namespace *ns);
  31 #else
  32 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  33 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
  34 #endif
  35
  36 #ifdef CONFIG_SYSVIPC
  37 int sem_init_ns(struct ipc_namespace *ns);
  38 int msg_init_ns(struct ipc_namespace *ns);
  39 int shm_init_ns(struct ipc_namespace *ns);
  40
  41 void sem_exit_ns(struct ipc_namespace *ns);
  42 void msg_exit_ns(struct ipc_namespace *ns);
  43 void shm_exit_ns(struct ipc_namespace *ns);
  44 #else
  45 static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
  46 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
  47 static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
  48
  49 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  50 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  51 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  52 #endif
  53
  54 /*
  55  * Structure that holds the parameters needed by the ipc operations
  56  * (see after)
  57  */
  58 struct ipc_params {
  59         key_t key;
  60         int flg;
  61         union {
  62                 size_t size;    /* for shared memories */
  63                 int nsems;      /* for semaphores */
  64         } u;                    /* holds the getnew() specific param */
  65 };
  66
  67 /*
  68  * Structure that holds some ipc operations. This structure is used to unify
  69  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  70  *      . routine to call to create a new ipc object. Can be one of newque,
  71  *        newary, newseg
  72  *      . routine to call to check permissions for a new ipc object.
  73  *        Can be one of security_msg_associate, security_sem_associate,
  74  *        security_shm_associate
  75  *      . routine to call for an extra check if needed
  76  */
  77 struct ipc_ops {
  78         int (*getnew)(struct ipc_namespace *, struct ipc_params *);
  79         int (*associate)(struct kern_ipc_perm *, int);
  80         int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
  81 };
  82
  83 struct seq_file;
  84 struct ipc_ids;
  85
  86 int ipc_init_ids(struct ipc_ids *);
  87 #ifdef CONFIG_PROC_FS
  88 void __init ipc_init_proc_interface(const char *path, const char *header,
  89                 int ids, int (*show)(struct seq_file *, void *));
  90 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
  91 #else
  92 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  93 #endif
  94
  95 #define IPC_SEM_IDS     0
  96 #define IPC_MSG_IDS     1
  97 #define IPC_SHM_IDS     2
  98
  99 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
 100 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
 101 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
 102
 103 /* must be called with ids->rwsem acquired for writing */
 104 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 105
 106 /* must be called with both locks acquired. */
 107 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 108
 109 /* must be called with both locks acquired. */
 110 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
 111
 112 /* must be called with ipcp locked */
 113 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 114
 115 /**
 116  * ipc_get_maxid - get the last assigned id
 117  * @ids: ipc identifier set
 118  *
 119  * Called with ipc_ids.rwsem held for reading.
 120  */
 121 static inline int ipc_get_maxid(struct ipc_ids *ids)
 122 {
 123         if (ids->in_use == 0)
 124                 return -1;
 125
 126         if (ids->in_use == IPCMNI)
 127                 return IPCMNI - 1;
 128
 129         return ids->max_id;
 130 }
 131
 132 /*
 133  * For allocation that need to be freed by RCU.
 134  * Objects are reference counted, they start with reference count 1.
 135  * getref increases the refcount, the putref call that reduces the recount
 136  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 137  *
 138  * refcount is initialized by ipc_addid(), before that point call_rcu()
 139  * must be used.
 140  */
 141 int ipc_rcu_getref(struct kern_ipc_perm *ptr);
 142 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 143                         void (*func)(struct rcu_head *head));
 144
 145 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 146 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 147
 148 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 149 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 150 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 151 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 152                                              struct ipc_ids *ids, int id, int cmd,
 153                                              struct ipc64_perm *perm, int extra_perm);
 154
 155 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
 156 {
 157         struct pid *old = *pos;
 158         if (old != pid) {
 159                 *pos = get_pid(pid);
 160                 put_pid(old);
 161         }
 162 }
 163
 164 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 165 /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
 166 # define ipc_parse_version(cmd) IPC_64
 167 #else
 168 int ipc_parse_version(int *cmd);
 169 #endif
 170
 171 extern void free_msg(struct msg_msg *msg);
 172 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 173 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 174 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 175
 176 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 177 {
 178         return uid / SEQ_MULTIPLIER != ipcp->seq;
 179 }
 180
 181 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 182 {
 183         spin_lock(&perm->lock);
 184 }
 185
 186 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 187 {
 188         spin_unlock(&perm->lock);
 189 }
 190
 191 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 192 {
 193         assert_spin_locked(&perm->lock);
 194 }
 195
 196 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 197 {
 198         ipc_unlock_object(perm);
 199         rcu_read_unlock();
 200 }
 201
 202 /*
 203  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 204  * where the respective ipc_ids.rwsem is not being held down.
 205  * Checks whether the ipc object is still around or if it's gone already, as
 206  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 207  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 208  * checkpoint case at sys_semtimedop() as noted in code commentary.
 209  */
 210 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 211 {
 212         return !perm->deleted;
 213 }
 214
 215 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 216 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 217                         const struct ipc_ops *ops, struct ipc_params *params);
 218 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 219                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 220
 221 #ifdef CONFIG_COMPAT
 222 #include <linux/compat.h>
 223 struct compat_ipc_perm {
 224         key_t key;
 225         __compat_uid_t uid;
 226         __compat_gid_t gid;
 227         __compat_uid_t cuid;
 228         __compat_gid_t cgid;
 229         compat_mode_t mode;
 230         unsigned short seq;
 231 };
 232
 233 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
 234 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
 235 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
 236 int get_compat_ipc64_perm(struct ipc64_perm *,
 237                           struct compat_ipc64_perm __user *);
 238
 239 static inline int compat_ipc_parse_version(int *cmd)
 240 {
 241 #ifdef  CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 242         int version = *cmd & IPC_64;
 243         *cmd &= ~IPC_64;
 244         return version;
 245 #else
 246         return IPC_64;
 247 #endif
 248 }
 249 #endif
 250
 251 /* for __ARCH_WANT_SYS_IPC */
 252 long ksys_semtimedop(int semid, struct sembuf __user *tsops,
 253                      unsigned int nsops,
 254                      const struct __kernel_timespec __user *timeout);
 255 long ksys_semget(key_t key, int nsems, int semflg);
 256 long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg);
 257 long ksys_msgget(key_t key, int msgflg);
 258 long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf);
 259 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
 260                  long msgtyp, int msgflg);
 261 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
 262                  int msgflg);
 263 long ksys_shmget(key_t key, size_t size, int shmflg);
 264 long ksys_shmdt(char __user *shmaddr);
 265 long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf);
 266
 267 /* for CONFIG_ARCH_WANT_OLD_COMPAT_IPC */
 268 long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
 269                             unsigned int nsops,
 270                             const struct compat_timespec __user *timeout);
 271 #ifdef CONFIG_COMPAT
 272 long compat_ksys_semctl(int semid, int semnum, int cmd, int arg);
 273 long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr);
 274 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
 275                         compat_long_t msgtyp, int msgflg);
 276 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
 277                        compat_ssize_t msgsz, int msgflg);
 278 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr);
 279 #endif /* CONFIG_COMPAT */
 280
 281 #endif