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 17 #define SEQ_MULTIPLIER (IPCMNI) 18 19 int sem_init(void); 20 int msg_init(void); 21 void shm_init(void); 22 23 struct ipc_namespace; 24 25 #ifdef CONFIG_POSIX_MQUEUE 26 extern void mq_clear_sbinfo(struct ipc_namespace *ns); 27 extern void mq_put_mnt(struct ipc_namespace *ns); 28 #else 29 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { } 30 static inline void mq_put_mnt(struct ipc_namespace *ns) { } 31 #endif 32 33 #ifdef CONFIG_SYSVIPC 34 int sem_init_ns(struct ipc_namespace *ns); 35 int msg_init_ns(struct ipc_namespace *ns); 36 int shm_init_ns(struct ipc_namespace *ns); 37 38 void sem_exit_ns(struct ipc_namespace *ns); 39 void msg_exit_ns(struct ipc_namespace *ns); 40 void shm_exit_ns(struct ipc_namespace *ns); 41 #else 42 static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; } 43 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; } 44 static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; } 45 46 static inline void sem_exit_ns(struct ipc_namespace *ns) { } 47 static inline void msg_exit_ns(struct ipc_namespace *ns) { } 48 static inline void shm_exit_ns(struct ipc_namespace *ns) { } 49 #endif 50 51 /* 52 * Structure that holds the parameters needed by the ipc operations 53 * (see after) 54 */ 55 struct ipc_params { 56 key_t key; 57 int flg; 58 union { 59 size_t size; /* for shared memories */ 60 int nsems; /* for semaphores */ 61 } u; /* holds the getnew() specific param */ 62 }; 63 64 /* 65 * Structure that holds some ipc operations. This structure is used to unify 66 * the calls to sys_msgget(), sys_semget(), sys_shmget() 67 * . routine to call to create a new ipc object. Can be one of newque, 68 * newary, newseg 69 * . routine to call to check permissions for a new ipc object. 70 * Can be one of security_msg_associate, security_sem_associate, 71 * security_shm_associate 72 * . routine to call for an extra check if needed 73 */ 74 struct ipc_ops { 75 int (*getnew)(struct ipc_namespace *, struct ipc_params *); 76 int (*associate)(struct kern_ipc_perm *, int); 77 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *); 78 }; 79 80 struct seq_file; 81 struct ipc_ids; 82 83 int ipc_init_ids(struct ipc_ids *); 84 #ifdef CONFIG_PROC_FS 85 void __init ipc_init_proc_interface(const char *path, const char *header, 86 int ids, int (*show)(struct seq_file *, void *)); 87 #else 88 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0) 89 #endif 90 91 #define IPC_SEM_IDS 0 92 #define IPC_MSG_IDS 1 93 #define IPC_SHM_IDS 2 94 95 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) 96 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER) 97 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX) 98 99 /* must be called with ids->rwsem acquired for writing */ 100 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); 101 102 /* must be called with ids->rwsem acquired for reading */ 103 int ipc_get_maxid(struct ipc_ids *); 104 105 /* must be called with both locks acquired. */ 106 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *); 107 108 /* must be called with both locks acquired. */ 109 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *); 110 111 /* must be called with ipcp locked */ 112 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg); 113 114 /* 115 * For allocation that need to be freed by RCU. 116 * Objects are reference counted, they start with reference count 1. 117 * getref increases the refcount, the putref call that reduces the recount 118 * to 0 schedules the rcu destruction. Caller must guarantee locking. 119 * 120 * refcount is initialized by ipc_addid(), before that point call_rcu() 121 * must be used. 122 */ 123 int ipc_rcu_getref(struct kern_ipc_perm *ptr); 124 void ipc_rcu_putref(struct kern_ipc_perm *ptr, 125 void (*func)(struct rcu_head *head)); 126 127 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int); 128 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id); 129 130 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out); 131 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out); 132 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out); 133 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, 134 struct ipc_ids *ids, int id, int cmd, 135 struct ipc64_perm *perm, int extra_perm); 136 137 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION 138 /* On IA-64, we always use the "64-bit version" of the IPC structures. */ 139 # define ipc_parse_version(cmd) IPC_64 140 #else 141 int ipc_parse_version(int *cmd); 142 #endif 143 144 extern void free_msg(struct msg_msg *msg); 145 extern struct msg_msg *load_msg(const void __user *src, size_t len); 146 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst); 147 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len); 148 149 static inline int ipc_buildid(int id, int seq) 150 { 151 return SEQ_MULTIPLIER * seq + id; 152 } 153 154 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) 155 { 156 return uid / SEQ_MULTIPLIER != ipcp->seq; 157 } 158 159 static inline void ipc_lock_object(struct kern_ipc_perm *perm) 160 { 161 spin_lock(&perm->lock); 162 } 163 164 static inline void ipc_unlock_object(struct kern_ipc_perm *perm) 165 { 166 spin_unlock(&perm->lock); 167 } 168 169 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm) 170 { 171 assert_spin_locked(&perm->lock); 172 } 173 174 static inline void ipc_unlock(struct kern_ipc_perm *perm) 175 { 176 ipc_unlock_object(perm); 177 rcu_read_unlock(); 178 } 179 180 /* 181 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths 182 * where the respective ipc_ids.rwsem is not being held down. 183 * Checks whether the ipc object is still around or if it's gone already, as 184 * ipc_rmid() may have already freed the ID while the ipc lock was spinning. 185 * Needs to be called with kern_ipc_perm.lock held -- exception made for one 186 * checkpoint case at sys_semtimedop() as noted in code commentary. 187 */ 188 static inline bool ipc_valid_object(struct kern_ipc_perm *perm) 189 { 190 return !perm->deleted; 191 } 192 193 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id); 194 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 195 const struct ipc_ops *ops, struct ipc_params *params); 196 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids, 197 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *)); 198 199 #ifdef CONFIG_COMPAT 200 #include <linux/compat.h> 201 struct compat_ipc_perm { 202 key_t key; 203 __compat_uid_t uid; 204 __compat_gid_t gid; 205 __compat_uid_t cuid; 206 __compat_gid_t cgid; 207 compat_mode_t mode; 208 unsigned short seq; 209 }; 210 211 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *); 212 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *); 213 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *); 214 int get_compat_ipc64_perm(struct ipc64_perm *, 215 struct compat_ipc64_perm __user *); 216 217 static inline int compat_ipc_parse_version(int *cmd) 218 { 219 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION 220 int version = *cmd & IPC_64; 221 *cmd &= ~IPC_64; 222 return version; 223 #else 224 return IPC_64; 225 #endif 226 } 227 #endif 228 #endif 229