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 void sem_init(void);
  22 void 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 void sem_init_ns(struct ipc_namespace *ns);
  38 void msg_init_ns(struct ipc_namespace *ns);
  39 void 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 void sem_init_ns(struct ipc_namespace *ns) { }
  46 static inline void msg_init_ns(struct ipc_namespace *ns) { }
  47 static inline void shm_init_ns(struct ipc_namespace *ns) { }
  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 void ipc_init_ids(struct ipc_ids *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_maxidx - get the highest assigned index
 117  * @ids: ipc identifier set
 118  *
 119  * Called with ipc_ids.rwsem held for reading.
 120  */
 121 static inline int ipc_get_maxidx(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_idx;
 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 bool 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_obtain_object_idr(struct ipc_ids *ids, int id);
 146
 147 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 148 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 149 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 150 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
 151                                              struct ipc_ids *ids, int id, int cmd,
 152                                              struct ipc64_perm *perm, int extra_perm);
 153
 154 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
 155 {
 156         struct pid *old = *pos;
 157         if (old != pid) {
 158                 *pos = get_pid(pid);
 159                 put_pid(old);
 160         }
 161 }
 162
 163 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 164 int ipc_parse_version(int *cmd);
 165 #endif
 166
 167 extern void free_msg(struct msg_msg *msg);
 168 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 169 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 170 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 171
 172 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
 173 {
 174         return ipcid_to_seqx(id) != ipcp->seq;
 175 }
 176
 177 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 178 {
 179         spin_lock(&perm->lock);
 180 }
 181
 182 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 183 {
 184         spin_unlock(&perm->lock);
 185 }
 186
 187 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 188 {
 189         assert_spin_locked(&perm->lock);
 190 }
 191
 192 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 193 {
 194         ipc_unlock_object(perm);
 195         rcu_read_unlock();
 196 }
 197
 198 /*
 199  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 200  * where the respective ipc_ids.rwsem is not being held down.
 201  * Checks whether the ipc object is still around or if it's gone already, as
 202  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 203  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 204  * checkpoint case at sys_semtimedop() as noted in code commentary.
 205  */
 206 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 207 {
 208         return !perm->deleted;
 209 }
 210
 211 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 212 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 213                         const struct ipc_ops *ops, struct ipc_params *params);
 214 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 215                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 216
 217 static inline int sem_check_semmni(struct ipc_namespace *ns) {
 218         /*
 219          * Check semmni range [0, IPCMNI]
 220          * semmni is the last element of sem_ctls[4] array
 221          */
 222         return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > IPCMNI))
 223                 ? -ERANGE : 0;
 224 }
 225
 226 #ifdef CONFIG_COMPAT
 227 #include <linux/compat.h>
 228 struct compat_ipc_perm {
 229         key_t key;
 230         __compat_uid_t uid;
 231         __compat_gid_t gid;
 232         __compat_uid_t cuid;
 233         __compat_gid_t cgid;
 234         compat_mode_t mode;
 235         unsigned short seq;
 236 };
 237
 238 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
 239 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
 240 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
 241 int get_compat_ipc64_perm(struct ipc64_perm *,
 242                           struct compat_ipc64_perm __user *);
 243
 244 static inline int compat_ipc_parse_version(int *cmd)
 245 {
 246         int version = *cmd & IPC_64;
 247         *cmd &= ~IPC_64;
 248         return version;
 249 }
 250 #endif
 251
 252 /* for __ARCH_WANT_SYS_IPC */
 253 long ksys_semtimedop(int semid, struct sembuf __user *tsops,
 254                      unsigned int nsops,
 255                      const struct __kernel_timespec __user *timeout);
 256 long ksys_semget(key_t key, int nsems, int semflg);
 257 long ksys_old_semctl(int semid, int semnum, int cmd, unsigned long arg);
 258 long ksys_msgget(key_t key, int msgflg);
 259 long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf);
 260 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
 261                  long msgtyp, int msgflg);
 262 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
 263                  int msgflg);
 264 long ksys_shmget(key_t key, size_t size, int shmflg);
 265 long ksys_shmdt(char __user *shmaddr);
 266 long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf);
 267
 268 /* for CONFIG_ARCH_WANT_OLD_COMPAT_IPC */
 269 long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
 270                             unsigned int nsops,
 271                             const struct old_timespec32 __user *timeout);
 272 #ifdef CONFIG_COMPAT
 273 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
 274 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
 275 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
 276                         compat_long_t msgtyp, int msgflg);
 277 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
 278                        compat_ssize_t msgsz, int msgflg);
 279 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
 280 #endif /* CONFIG_COMPAT */
 281
 282 #endif