xref: /openbmc/linux/ipc/util.h (revision a2818ee4)
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 static inline int sem_check_semmni(struct ipc_namespace *ns) {
221 	/*
222 	 * Check semmni range [0, IPCMNI]
223 	 * semmni is the last element of sem_ctls[4] array
224 	 */
225 	return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > IPCMNI))
226 		? -ERANGE : 0;
227 }
228 
229 #ifdef CONFIG_COMPAT
230 #include <linux/compat.h>
231 struct compat_ipc_perm {
232 	key_t key;
233 	__compat_uid_t uid;
234 	__compat_gid_t gid;
235 	__compat_uid_t cuid;
236 	__compat_gid_t cgid;
237 	compat_mode_t mode;
238 	unsigned short seq;
239 };
240 
241 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
242 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
243 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
244 int get_compat_ipc64_perm(struct ipc64_perm *,
245 			  struct compat_ipc64_perm __user *);
246 
247 static inline int compat_ipc_parse_version(int *cmd)
248 {
249 #ifdef	CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
250 	int version = *cmd & IPC_64;
251 	*cmd &= ~IPC_64;
252 	return version;
253 #else
254 	return IPC_64;
255 #endif
256 }
257 #endif
258 
259 /* for __ARCH_WANT_SYS_IPC */
260 long ksys_semtimedop(int semid, struct sembuf __user *tsops,
261 		     unsigned int nsops,
262 		     const struct __kernel_timespec __user *timeout);
263 long ksys_semget(key_t key, int nsems, int semflg);
264 long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg);
265 long ksys_msgget(key_t key, int msgflg);
266 long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf);
267 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
268 		 long msgtyp, int msgflg);
269 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
270 		 int msgflg);
271 long ksys_shmget(key_t key, size_t size, int shmflg);
272 long ksys_shmdt(char __user *shmaddr);
273 long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf);
274 
275 /* for CONFIG_ARCH_WANT_OLD_COMPAT_IPC */
276 long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
277 			    unsigned int nsops,
278 			    const struct old_timespec32 __user *timeout);
279 #ifdef CONFIG_COMPAT
280 long compat_ksys_semctl(int semid, int semnum, int cmd, int arg);
281 long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr);
282 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
283 			compat_long_t msgtyp, int msgflg);
284 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
285 		       compat_ssize_t msgsz, int msgflg);
286 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr);
287 #endif /* CONFIG_COMPAT */
288 
289 #endif
290