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 293