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 #include <linux/pid.h>
  18
  19 /*
  20  * The IPC ID contains 2 separate numbers - index and sequence number.
  21  * By default,
  22  *   bits  0-14: index (32k, 15 bits)
  23  *   bits 15-30: sequence number (64k, 16 bits)
  24  *
  25  * When IPCMNI extension mode is turned on, the composition changes:
  26  *   bits  0-23: index (16M, 24 bits)
  27  *   bits 24-30: sequence number (128, 7 bits)
  28  */
  29 #define IPCMNI_SHIFT            15
  30 #define IPCMNI_EXTEND_SHIFT     24
  31 #define IPCMNI_EXTEND_MIN_CYCLE (RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE)
  32 #define IPCMNI                  (1 << IPCMNI_SHIFT)
  33 #define IPCMNI_EXTEND           (1 << IPCMNI_EXTEND_SHIFT)
  34
  35 #ifdef CONFIG_SYSVIPC_SYSCTL
  36 extern int ipc_mni;
  37 extern int ipc_mni_shift;
  38 extern int ipc_min_cycle;
  39
  40 #define ipcmni_seq_shift()      ipc_mni_shift
  41 #define IPCMNI_IDX_MASK         ((1 << ipc_mni_shift) - 1)
  42
  43 #else /* CONFIG_SYSVIPC_SYSCTL */
  44
  45 #define ipc_mni                 IPCMNI
  46 #define ipc_min_cycle           ((int)RADIX_TREE_MAP_SIZE)
  47 #define ipcmni_seq_shift()      IPCMNI_SHIFT
  48 #define IPCMNI_IDX_MASK         ((1 << IPCMNI_SHIFT) - 1)
  49 #endif /* CONFIG_SYSVIPC_SYSCTL */
  50
  51 void sem_init(void);
  52 void msg_init(void);
  53 void shm_init(void);
  54
  55 struct ipc_namespace;
  56 struct pid_namespace;
  57
  58 #ifdef CONFIG_POSIX_MQUEUE
  59 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  60 #else
  61 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  62 #endif
  63
  64 #ifdef CONFIG_SYSVIPC
  65 void sem_init_ns(struct ipc_namespace *ns);
  66 int msg_init_ns(struct ipc_namespace *ns);
  67 void shm_init_ns(struct ipc_namespace *ns);
  68
  69 void sem_exit_ns(struct ipc_namespace *ns);
  70 void msg_exit_ns(struct ipc_namespace *ns);
  71 void shm_exit_ns(struct ipc_namespace *ns);
  72 #else
  73 static inline void sem_init_ns(struct ipc_namespace *ns) { }
  74 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
  75 static inline void shm_init_ns(struct ipc_namespace *ns) { }
  76
  77 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  78 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  79 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  80 #endif
  81
  82 /*
  83  * Structure that holds the parameters needed by the ipc operations
  84  * (see after)
  85  */
  86 struct ipc_params {
  87         key_t key;
  88         int flg;
  89         union {
  90                 size_t size;    /* for shared memories */
  91                 int nsems;      /* for semaphores */
  92         } u;                    /* holds the getnew() specific param */
  93 };
  94
  95 /*
  96  * Structure that holds some ipc operations. This structure is used to unify
  97  * the calls to sys_msgget(), sys_semget(), sys_shmget()
  98  *      . routine to call to create a new ipc object. Can be one of newque,
  99  *        newary, newseg
 100  *      . routine to call to check permissions for a new ipc object.
 101  *        Can be one of security_msg_associate, security_sem_associate,
 102  *        security_shm_associate
 103  *      . routine to call for an extra check if needed
 104  */
 105 struct ipc_ops {
 106         int (*getnew)(struct ipc_namespace *, struct ipc_params *);
 107         int (*associate)(struct kern_ipc_perm *, int);
 108         int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
 109 };
 110
 111 struct seq_file;
 112 struct ipc_ids;
 113
 114 void ipc_init_ids(struct ipc_ids *ids);
 115 #ifdef CONFIG_PROC_FS
 116 void __init ipc_init_proc_interface(const char *path, const char *header,
 117                 int ids, int (*show)(struct seq_file *, void *));
 118 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
 119 #else
 120 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
 121 #endif
 122
 123 #define IPC_SEM_IDS     0
 124 #define IPC_MSG_IDS     1
 125 #define IPC_SHM_IDS     2
 126
 127 #define ipcid_to_idx(id)  ((id) & IPCMNI_IDX_MASK)
 128 #define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
 129 #define ipcid_seq_max()   (INT_MAX >> ipcmni_seq_shift())
 130
 131 /* must be called with ids->rwsem acquired for writing */
 132 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 133
 134 /* must be called with both locks acquired. */
 135 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 136
 137 /* must be called with both locks acquired. */
 138 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
 139
 140 /* must be called with ipcp locked */
 141 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 142
 143 /**
 144  * ipc_get_maxidx - get the highest assigned index
 145  * @ids: ipc identifier set
 146  *
 147  * The function returns the highest assigned index for @ids. The function
 148  * doesn't scan the idr tree, it uses a cached value.
 149  *
 150  * Called with ipc_ids.rwsem held for reading.
 151  */
 152 static inline int ipc_get_maxidx(struct ipc_ids *ids)
 153 {
 154         if (ids->in_use == 0)
 155                 return -1;
 156
 157         if (ids->in_use == ipc_mni)
 158                 return ipc_mni - 1;
 159
 160         return ids->max_idx;
 161 }
 162
 163 /*
 164  * For allocation that need to be freed by RCU.
 165  * Objects are reference counted, they start with reference count 1.
 166  * getref increases the refcount, the putref call that reduces the recount
 167  * to 0 schedules the rcu destruction. Caller must guarantee locking.
 168  *
 169  * refcount is initialized by ipc_addid(), before that point call_rcu()
 170  * must be used.
 171  */
 172 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
 173 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 174                         void (*func)(struct rcu_head *head));
 175
 176 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
 177
 178 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
 179 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
 180 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
 181 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
 182                                              struct ipc_ids *ids, int id, int cmd,
 183                                              struct ipc64_perm *perm, int extra_perm);
 184
 185 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
 186 {
 187         struct pid *old = *pos;
 188         if (old != pid) {
 189                 *pos = get_pid(pid);
 190                 put_pid(old);
 191         }
 192 }
 193
 194 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 195 int ipc_parse_version(int *cmd);
 196 #endif
 197
 198 extern void free_msg(struct msg_msg *msg);
 199 extern struct msg_msg *load_msg(const void __user *src, size_t len);
 200 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 201 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 202
 203 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
 204 {
 205         return ipcid_to_seqx(id) != ipcp->seq;
 206 }
 207
 208 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
 209 {
 210         spin_lock(&perm->lock);
 211 }
 212
 213 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
 214 {
 215         spin_unlock(&perm->lock);
 216 }
 217
 218 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
 219 {
 220         assert_spin_locked(&perm->lock);
 221 }
 222
 223 static inline void ipc_unlock(struct kern_ipc_perm *perm)
 224 {
 225         ipc_unlock_object(perm);
 226         rcu_read_unlock();
 227 }
 228
 229 /*
 230  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
 231  * where the respective ipc_ids.rwsem is not being held down.
 232  * Checks whether the ipc object is still around or if it's gone already, as
 233  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
 234  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
 235  * checkpoint case at sys_semtimedop() as noted in code commentary.
 236  */
 237 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
 238 {
 239         return !perm->deleted;
 240 }
 241
 242 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
 243 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 244                         const struct ipc_ops *ops, struct ipc_params *params);
 245 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
 246                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
 247
 248 static inline int sem_check_semmni(struct ipc_namespace *ns) {
 249         /*
 250          * Check semmni range [0, ipc_mni]
 251          * semmni is the last element of sem_ctls[4] array
 252          */
 253         return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
 254                 ? -ERANGE : 0;
 255 }
 256
 257 #ifdef CONFIG_COMPAT
 258 #include <linux/compat.h>
 259 struct compat_ipc_perm {
 260         key_t key;
 261         __compat_uid_t uid;
 262         __compat_gid_t gid;
 263         __compat_uid_t cuid;
 264         __compat_gid_t cgid;
 265         compat_mode_t mode;
 266         unsigned short seq;
 267 };
 268
 269 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
 270 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
 271 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
 272 int get_compat_ipc64_perm(struct ipc64_perm *,
 273                           struct compat_ipc64_perm __user *);
 274
 275 static inline int compat_ipc_parse_version(int *cmd)
 276 {
 277         int version = *cmd & IPC_64;
 278         *cmd &= ~IPC_64;
 279         return version;
 280 }
 281
 282 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
 283 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
 284 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
 285                         compat_long_t msgtyp, int msgflg);
 286 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
 287                        compat_ssize_t msgsz, int msgflg);
 288 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
 289
 290 #endif
 291
 292 #endif