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Linux/ipc/util.h

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  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 

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