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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 #include <linux/ipc_namespace.h>
 17 
 18 #define IPCMNI 32768  /* <= MAX_INT limit for ipc arrays (including sysctl changes) */
 19 #define SEQ_MULTIPLIER  (IPCMNI)
 20 
 21 void sem_init(void);
 22 void msg_init(void);
 23 void shm_init(void);
 24 
 25 struct ipc_namespace;
 26 struct pid_namespace;
 27 
 28 #ifdef CONFIG_POSIX_MQUEUE
 29 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
 30 extern void mq_put_mnt(struct ipc_namespace *ns);
 31 #else
 32 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
 33 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
 34 #endif
 35 
 36 #ifdef CONFIG_SYSVIPC
 37 void sem_init_ns(struct ipc_namespace *ns);
 38 void msg_init_ns(struct ipc_namespace *ns);
 39 void shm_init_ns(struct ipc_namespace *ns);
 40 
 41 void sem_exit_ns(struct ipc_namespace *ns);
 42 void msg_exit_ns(struct ipc_namespace *ns);
 43 void shm_exit_ns(struct ipc_namespace *ns);
 44 #else
 45 static inline void sem_init_ns(struct ipc_namespace *ns) { }
 46 static inline void msg_init_ns(struct ipc_namespace *ns) { }
 47 static inline void shm_init_ns(struct ipc_namespace *ns) { }
 48 
 49 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
 50 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
 51 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
 52 #endif
 53 
 54 /*
 55  * Structure that holds the parameters needed by the ipc operations
 56  * (see after)
 57  */
 58 struct ipc_params {
 59         key_t key;
 60         int flg;
 61         union {
 62                 size_t size;    /* for shared memories */
 63                 int nsems;      /* for semaphores */
 64         } u;                    /* holds the getnew() specific param */
 65 };
 66 
 67 /*
 68  * Structure that holds some ipc operations. This structure is used to unify
 69  * the calls to sys_msgget(), sys_semget(), sys_shmget()
 70  *      . routine to call to create a new ipc object. Can be one of newque,
 71  *        newary, newseg
 72  *      . routine to call to check permissions for a new ipc object.
 73  *        Can be one of security_msg_associate, security_sem_associate,
 74  *        security_shm_associate
 75  *      . routine to call for an extra check if needed
 76  */
 77 struct ipc_ops {
 78         int (*getnew)(struct ipc_namespace *, struct ipc_params *);
 79         int (*associate)(struct kern_ipc_perm *, int);
 80         int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
 81 };
 82 
 83 struct seq_file;
 84 struct ipc_ids;
 85 
 86 void ipc_init_ids(struct ipc_ids *ids);
 87 #ifdef CONFIG_PROC_FS
 88 void __init ipc_init_proc_interface(const char *path, const char *header,
 89                 int ids, int (*show)(struct seq_file *, void *));
 90 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
 91 #else
 92 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
 93 #endif
 94 
 95 #define IPC_SEM_IDS     0
 96 #define IPC_MSG_IDS     1
 97 #define IPC_SHM_IDS     2
 98 
 99 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
100 #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
101 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
102 
103 /* must be called with ids->rwsem acquired for writing */
104 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
105 
106 /* must be called with both locks acquired. */
107 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
108 
109 /* must be called with both locks acquired. */
110 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
111 
112 /* must be called with ipcp locked */
113 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
114 
115 /**
116  * ipc_get_maxidx - get the highest assigned index
117  * @ids: ipc identifier set
118  *
119  * Called with ipc_ids.rwsem held for reading.
120  */
121 static inline int ipc_get_maxidx(struct ipc_ids *ids)
122 {
123         if (ids->in_use == 0)
124                 return -1;
125 
126         if (ids->in_use == IPCMNI)
127                 return IPCMNI - 1;
128 
129         return ids->max_idx;
130 }
131 
132 /*
133  * For allocation that need to be freed by RCU.
134  * Objects are reference counted, they start with reference count 1.
135  * getref increases the refcount, the putref call that reduces the recount
136  * to 0 schedules the rcu destruction. Caller must guarantee locking.
137  *
138  * refcount is initialized by ipc_addid(), before that point call_rcu()
139  * must be used.
140  */
141 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
142 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
143                         void (*func)(struct rcu_head *head));
144 
145 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
146 
147 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
148 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
149 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
150 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
151                                              struct ipc_ids *ids, int id, int cmd,
152                                              struct ipc64_perm *perm, int extra_perm);
153 
154 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
155 {
156         struct pid *old = *pos;
157         if (old != pid) {
158                 *pos = get_pid(pid);
159                 put_pid(old);
160         }
161 }
162 
163 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
164 /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
165 # define ipc_parse_version(cmd) IPC_64
166 #else
167 int ipc_parse_version(int *cmd);
168 #endif
169 
170 extern void free_msg(struct msg_msg *msg);
171 extern struct msg_msg *load_msg(const void __user *src, size_t len);
172 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
173 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
174 
175 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
176 {
177         return ipcid_to_seqx(id) != ipcp->seq;
178 }
179 
180 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
181 {
182         spin_lock(&perm->lock);
183 }
184 
185 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
186 {
187         spin_unlock(&perm->lock);
188 }
189 
190 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
191 {
192         assert_spin_locked(&perm->lock);
193 }
194 
195 static inline void ipc_unlock(struct kern_ipc_perm *perm)
196 {
197         ipc_unlock_object(perm);
198         rcu_read_unlock();
199 }
200 
201 /*
202  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
203  * where the respective ipc_ids.rwsem is not being held down.
204  * Checks whether the ipc object is still around or if it's gone already, as
205  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
206  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
207  * checkpoint case at sys_semtimedop() as noted in code commentary.
208  */
209 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
210 {
211         return !perm->deleted;
212 }
213 
214 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
215 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
216                         const struct ipc_ops *ops, struct ipc_params *params);
217 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
218                 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
219 
220 #ifdef CONFIG_COMPAT
221 #include <linux/compat.h>
222 struct compat_ipc_perm {
223         key_t key;
224         __compat_uid_t uid;
225         __compat_gid_t gid;
226         __compat_uid_t cuid;
227         __compat_gid_t cgid;
228         compat_mode_t mode;
229         unsigned short seq;
230 };
231 
232 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
233 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
234 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
235 int get_compat_ipc64_perm(struct ipc64_perm *,
236                           struct compat_ipc64_perm __user *);
237 
238 static inline int compat_ipc_parse_version(int *cmd)
239 {
240 #ifdef  CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
241         int version = *cmd & IPC_64;
242         *cmd &= ~IPC_64;
243         return version;
244 #else
245         return IPC_64;
246 #endif
247 }
248 #endif
249 
250 /* for __ARCH_WANT_SYS_IPC */
251 long ksys_semtimedop(int semid, struct sembuf __user *tsops,
252                      unsigned int nsops,
253                      const struct __kernel_timespec __user *timeout);
254 long ksys_semget(key_t key, int nsems, int semflg);
255 long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg);
256 long ksys_msgget(key_t key, int msgflg);
257 long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf);
258 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
259                  long msgtyp, int msgflg);
260 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
261                  int msgflg);
262 long ksys_shmget(key_t key, size_t size, int shmflg);
263 long ksys_shmdt(char __user *shmaddr);
264 long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf);
265 
266 /* for CONFIG_ARCH_WANT_OLD_COMPAT_IPC */
267 long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
268                             unsigned int nsops,
269                             const struct compat_timespec __user *timeout);
270 #ifdef CONFIG_COMPAT
271 long compat_ksys_semctl(int semid, int semnum, int cmd, int arg);
272 long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr);
273 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
274                         compat_long_t msgtyp, int msgflg);
275 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
276                        compat_ssize_t msgsz, int msgflg);
277 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr);
278 #endif /* CONFIG_COMPAT */
279 
280 #endif
281 

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