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 294