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