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 #define SEQ_MULTIPLIER (IPCMNI) 19 20 int sem_init(void); 21 int msg_init(void); 22 void shm_init(void); 23 24 struct ipc_namespace; 25 26 #ifdef CONFIG_POSIX_MQUEUE 27 extern void mq_clear_sbinfo(struct ipc_namespace *ns); 28 extern void mq_put_mnt(struct ipc_namespace *ns); 29 #else 30 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { } 31 static inline void mq_put_mnt(struct ipc_namespace *ns) { } 32 #endif 33 34 #ifdef CONFIG_SYSVIPC 35 int sem_init_ns(struct ipc_namespace *ns); 36 int msg_init_ns(struct ipc_namespace *ns); 37 int shm_init_ns(struct ipc_namespace *ns); 38 39 void sem_exit_ns(struct ipc_namespace *ns); 40 void msg_exit_ns(struct ipc_namespace *ns); 41 void shm_exit_ns(struct ipc_namespace *ns); 42 #else 43 static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; } 44 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; } 45 static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; } 46 47 static inline void sem_exit_ns(struct ipc_namespace *ns) { } 48 static inline void msg_exit_ns(struct ipc_namespace *ns) { } 49 static inline void shm_exit_ns(struct ipc_namespace *ns) { } 50 #endif 51 52 /* 53 * Structure that holds the parameters needed by the ipc operations 54 * (see after) 55 */ 56 struct ipc_params { 57 key_t key; 58 int flg; 59 union { 60 size_t size; /* for shared memories */ 61 int nsems; /* for semaphores */ 62 } u; /* holds the getnew() specific param */ 63 }; 64 65 /* 66 * Structure that holds some ipc operations. This structure is used to unify 67 * the calls to sys_msgget(), sys_semget(), sys_shmget() 68 * . routine to call to create a new ipc object. Can be one of newque, 69 * newary, newseg 70 * . routine to call to check permissions for a new ipc object. 71 * Can be one of security_msg_associate, security_sem_associate, 72 * security_shm_associate 73 * . routine to call for an extra check if needed 74 */ 75 struct ipc_ops { 76 int (*getnew)(struct ipc_namespace *, struct ipc_params *); 77 int (*associate)(struct kern_ipc_perm *, int); 78 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *); 79 }; 80 81 struct seq_file; 82 struct ipc_ids; 83 84 int ipc_init_ids(struct ipc_ids *); 85 #ifdef CONFIG_PROC_FS 86 void __init ipc_init_proc_interface(const char *path, const char *header, 87 int ids, int (*show)(struct seq_file *, void *)); 88 #else 89 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) 90 #endif 91 92 #define IPC_SEM_IDS 0 93 #define IPC_MSG_IDS 1 94 #define IPC_SHM_IDS 2 95 96 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) 97 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER) 98 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX) 99 100 /* must be called with ids->rwsem acquired for writing */ 101 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); 102 103 /* must be called with both locks acquired. */ 104 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); 105 106 /* must be called with both locks acquired. */ 107 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *); 108 109 /* must be called with ipcp locked */ 110 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg); 111 112 /** 113 * ipc_get_maxid - get the last assigned id 114 * @ids: ipc identifier set 115 * 116 * Called with ipc_ids.rwsem held for reading. 117 */ 118 static inline int ipc_get_maxid(struct ipc_ids *ids) 119 { 120 if (ids->in_use == 0) 121 return -1; 122 123 if (ids->in_use == IPCMNI) 124 return IPCMNI - 1; 125 126 return ids->max_id; 127 } 128 129 /* 130 * For allocation that need to be freed by RCU. 131 * Objects are reference counted, they start with reference count 1. 132 * getref increases the refcount, the putref call that reduces the recount 133 * to 0 schedules the rcu destruction. Caller must guarantee locking. 134 * 135 * refcount is initialized by ipc_addid(), before that point call_rcu() 136 * must be used. 137 */ 138 int ipc_rcu_getref(struct kern_ipc_perm *ptr); 139 void ipc_rcu_putref(struct kern_ipc_perm *ptr, 140 void (*func)(struct rcu_head *head)); 141 142 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); 143 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id); 144 145 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); 146 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); 147 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); 148 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, 149 struct ipc_ids *ids, int id, int cmd, 150 struct ipc64_perm *perm, int extra_perm); 151 152 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 153 /* On IA-64, we always use the "64-bit version" of the IPC structures. */ 154 # define ipc_parse_version(cmd) IPC_64 155 #else 156 int ipc_parse_version(int *cmd); 157 #endif 158 159 extern void free_msg(struct msg_msg *msg); 160 extern struct msg_msg *load_msg(const void __user *src, size_t len); 161 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst); 162 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len); 163 164 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) 165 { 166 return uid / SEQ_MULTIPLIER != ipcp->seq; 167 } 168 169 static inline void ipc_lock_object(struct kern_ipc_perm *perm) 170 { 171 spin_lock(&perm->lock); 172 } 173 174 static inline void ipc_unlock_object(struct kern_ipc_perm *perm) 175 { 176 spin_unlock(&perm->lock); 177 } 178 179 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm) 180 { 181 assert_spin_locked(&perm->lock); 182 } 183 184 static inline void ipc_unlock(struct kern_ipc_perm *perm) 185 { 186 ipc_unlock_object(perm); 187 rcu_read_unlock(); 188 } 189 190 /* 191 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths 192 * where the respective ipc_ids.rwsem is not being held down. 193 * Checks whether the ipc object is still around or if it's gone already, as 194 * ipc_rmid() may have already freed the ID while the ipc lock was spinning. 195 * Needs to be called with kern_ipc_perm.lock held -- exception made for one 196 * checkpoint case at sys_semtimedop() as noted in code commentary. 197 */ 198 static inline bool ipc_valid_object(struct kern_ipc_perm *perm) 199 { 200 return !perm->deleted; 201 } 202 203 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); 204 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 205 const struct ipc_ops *ops, struct ipc_params *params); 206 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, 207 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)); 208 209 #ifdef CONFIG_COMPAT 210 #include <linux/compat.h> 211 struct compat_ipc_perm { 212 key_t key; 213 __compat_uid_t uid; 214 __compat_gid_t gid; 215 __compat_uid_t cuid; 216 __compat_gid_t cgid; 217 compat_mode_t mode; 218 unsigned short seq; 219 }; 220 221 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *); 222 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *); 223 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *); 224 int get_compat_ipc64_perm(struct ipc64_perm *, 225 struct compat_ipc64_perm __user *); 226 227 static inline int compat_ipc_parse_version(int *cmd) 228 { 229 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION 230 int version = *cmd & IPC_64; 231 *cmd &= ~IPC_64; 232 return version; 233 #else 234 return IPC_64; 235 #endif 236 } 237 #endif 238 #endif 239