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 /*
  19  * The IPC ID contains 2 separate numbers - index and sequence number.
  20  * By default,
  21  *   bits  0-14: index (32k, 15 bits)
  22  *   bits 15-30: sequence number (64k, 16 bits)
  23  *
  24  * When IPCMNI extension mode is turned on, the composition changes:
  25  *   bits  0-23: index (16M, 24 bits)
  26  *   bits 24-30: sequence number (128, 7 bits)
  27  */
  28 #define IPCMNI_SHIFT            15
  29 #define IPCMNI_EXTEND_SHIFT     24
  30 #define IPCMNI_EXTEND_MIN_CYCLE (RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE)
  31 #define IPCMNI                  (1 << IPCMNI_SHIFT)
  32 #define IPCMNI_EXTEND           (1 << IPCMNI_EXTEND_SHIFT)
  33
  34 #ifdef CONFIG_SYSVIPC_SYSCTL
  35 extern int ipc_mni;
  36 extern int ipc_mni_shift;
  37 extern int ipc_min_cycle;
  38
  39 #define ipcmni_seq_shift()      ipc_mni_shift
  40 #define IPCMNI_IDX_MASK         ((1 << ipc_mni_shift) - 1)
  41
  42 #else /* CONFIG_SYSVIPC_SYSCTL */
  43
  44 #define ipc_mni                 IPCMNI
  45 #define ipc_min_cycle           ((int)RADIX_TREE_MAP_SIZE)
  46 #define ipcmni_seq_shift()      IPCMNI_SHIFT
  47 #define IPCMNI_IDX_MASK         ((1 << IPCMNI_SHIFT) - 1)
  48 #endif /* CONFIG_SYSVIPC_SYSCTL */
  49
  50 void sem_init(void);
  51 void msg_init(void);
  52 void shm_init(void);
  53
  54 struct ipc_namespace;
  55 struct pid_namespace;
  56
  57 #ifdef CONFIG_POSIX_MQUEUE
  58 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  59 extern void mq_put_mnt(struct ipc_namespace *ns);
  60 #else
  61 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  62 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
  63 #endif
  64
  65 #ifdef CONFIG_SYSVIPC
  66 void sem_init_ns(struct ipc_namespace *ns);
  67 void msg_init_ns(struct ipc_namespace *ns);
  68 void shm_init_ns(struct ipc_namespace *ns);
  69
  70 void sem_exit_ns(struct ipc_namespace *ns);
  71 void msg_exit_ns(struct ipc_namespace *ns);
  72 void shm_exit_ns(struct ipc_namespace *ns);
  73 #else
  74 static inline void sem_init_ns(struct ipc_namespace *ns) { }
  75 static inline void msg_init_ns(struct ipc_namespace *ns) { }
  76 static inline void shm_init_ns(struct ipc_namespace *ns) { }
  77
  78 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  79 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  80 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  81 #endif
  82
  83 /*
  84  * Structure that holds the parameters needed by the ipc operations
  85  * (see after)
  86  */
  87 struct ipc_params {
  88         key_t key;
  89         int flg;
  90         union {
  91                 size_t size;    /* for shared memories */
  92                 int nsems;      /* for semaphores */
  93         } u;                    /* holds the getnew() specific param */
  94 };
  95
  96 /*
  97  * Structure that holds some ipc operations. This structure is used to unify
  98  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  99  *      . routine to call to create a new ipc object. Can be one of newque,
 100  *        newary, newseg
 101  *      . routine to call to check permissions for a new ipc object.
 102  *        Can be one of security_msg_associate, security_sem_associate,
 103  *        security_shm_associate
 104  *      . routine to call for an extra check if needed
 105  */
 106 struct ipc_ops {
 107         int (*getnew)(struct ipc_namespace *, struct ipc_params *);
 108         int (*associate)(struct kern_ipc_perm *, int);
 109         int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
 110 };
 111
 112 struct seq_file;
 113 struct ipc_ids;
 114
 115 void ipc_init_ids(struct ipc_ids *ids);
 116 #ifdef CONFIG_PROC_FS
 117 void __init ipc_init_proc_interface(const char *path, const char *header,
 118                 int ids, int (*show)(struct seq_file *, void *));
 119 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
 120 #else
 121 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
 122 #endif
 123
 124 #define IPC_SEM_IDS     0
 125 #define IPC_MSG_IDS     1
 126 #define IPC_SHM_IDS     2
 127
 128 #define ipcid_to_idx(id)  ((id) & IPCMNI_IDX_MASK)
 129 #define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
 130 #define ipcid_seq_max()   (INT_MAX >> ipcmni_seq_shift())
 131
 132 /* must be called with ids->rwsem acquired for writing */
 133 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 134
 135 /* must be called with both locks acquired. */
 136 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 137
 138 /* must be called with both locks acquired. */
 139 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
 140
 141 /* must be called with ipcp locked */
 142 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 143
 144 /**
 145  * ipc_get_maxidx - get the highest assigned index
 146  * @ids: ipc identifier set
 147  *
 148  * The function returns the highest assigned index for @ids. The function
 149  * doesn't scan the idr tree, it uses a cached value.
 150  *
 151  * Called with ipc_ids.rwsem held for reading.
 152  */
 153 static inline int ipc_get_maxidx(struct ipc_ids *ids)
 154 {
 155         if (ids->in_use == 0)
 156                 return -1;
 157
 158         if (ids->in_use == ipc_mni)
 159                 return ipc_mni - 1;
 160
 161         return ids->max_idx;
 162 }
 163
 164 /*
 165  * For allocation that need to be freed by RCU.
 166  * Objects are reference counted, they start with reference count 1.
 167  * getref increases the refcount, the putref call that reduces the recount
 168  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 169  *
 170  * refcount is initialized by ipc_addid(), before that point call_rcu()
 171  * must be used.
 172  */
 173 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
 174 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 175                         void (*func)(struct rcu_head *head));
 176
 177 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 178
 179 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 180 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 181 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 182 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
 183                                              struct ipc_ids *ids, int id, int cmd,
 184                                              struct ipc64_perm *perm, int extra_perm);
 185
 186 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
 187 {
 188         struct pid *old = *pos;
 189         if (old != pid) {
 190                 *pos = get_pid(pid);
 191                 put_pid(old);
 192         }
 193 }
 194
 195 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 196 int ipc_parse_version(int *cmd);
 197 #endif
 198
 199 extern void free_msg(struct msg_msg *msg);
 200 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 201 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 202 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 203
 204 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
 205 {
 206         return ipcid_to_seqx(id) != ipcp->seq;
 207 }
 208
 209 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 210 {
 211         spin_lock(&perm->lock);
 212 }
 213
 214 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 215 {
 216         spin_unlock(&perm->lock);
 217 }
 218
 219 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 220 {
 221         assert_spin_locked(&perm->lock);
 222 }
 223
 224 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 225 {
 226         ipc_unlock_object(perm);
 227         rcu_read_unlock();
 228 }
 229
 230 /*
 231  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 232  * where the respective ipc_ids.rwsem is not being held down.
 233  * Checks whether the ipc object is still around or if it's gone already, as
 234  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 235  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 236  * checkpoint case at sys_semtimedop() as noted in code commentary.
 237  */
 238 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 239 {
 240         return !perm->deleted;
 241 }
 242
 243 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 244 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 245                         const struct ipc_ops *ops, struct ipc_params *params);
 246 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 247                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 248
 249 static inline int sem_check_semmni(struct ipc_namespace *ns) {
 250         /*
 251          * Check semmni range [0, ipc_mni]
 252          * semmni is the last element of sem_ctls[4] array
 253          */
 254         return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
 255                 ? -ERANGE : 0;
 256 }
 257
 258 #ifdef CONFIG_COMPAT
 259 #include <linux/compat.h>
 260 struct compat_ipc_perm {
 261         key_t key;
 262         __compat_uid_t uid;
 263         __compat_gid_t gid;
 264         __compat_uid_t cuid;
 265         __compat_gid_t cgid;
 266         compat_mode_t mode;
 267         unsigned short seq;
 268 };
 269
 270 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
 271 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
 272 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
 273 int get_compat_ipc64_perm(struct ipc64_perm *,
 274                           struct compat_ipc64_perm __user *);
 275
 276 static inline int compat_ipc_parse_version(int *cmd)
 277 {
 278         int version = *cmd & IPC_64;
 279         *cmd &= ~IPC_64;
 280         return version;
 281 }
 282
 283 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
 284 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
 285 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
 286                         compat_long_t msgtyp, int msgflg);
 287 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
 288                        compat_ssize_t msgsz, int msgflg);
 289 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
 290
 291 #endif
 292
 293 #endif