xref: /linux/ipc/util.h (revision fb377eb8)
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 /*
19  * The IPC ID contains 2 separate numbers - index and sequence number.
20  * By default,
21  *   bits  0-14: index (32k, 15 bits)
22  *   bits 15-30: sequence number (64k, 16 bits)
23  *
24  * When IPCMNI extension mode is turned on, the composition changes:
25  *   bits  0-23: index (16M, 24 bits)
26  *   bits 24-30: sequence number (128, 7 bits)
27  */
28 #define IPCMNI_SHIFT		15
29 #define IPCMNI_EXTEND_SHIFT	24
30 #define IPCMNI_EXTEND_MIN_CYCLE	(RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE)
31 #define IPCMNI			(1 << IPCMNI_SHIFT)
32 #define IPCMNI_EXTEND		(1 << IPCMNI_EXTEND_SHIFT)
33 
34 #ifdef CONFIG_SYSVIPC_SYSCTL
35 extern int ipc_mni;
36 extern int ipc_mni_shift;
37 extern int ipc_min_cycle;
38 
39 #define ipcmni_seq_shift()	ipc_mni_shift
40 #define IPCMNI_IDX_MASK		((1 << ipc_mni_shift) - 1)
41 
42 #else /* CONFIG_SYSVIPC_SYSCTL */
43 
44 #define ipc_mni			IPCMNI
45 #define ipc_min_cycle		((int)RADIX_TREE_MAP_SIZE)
46 #define ipcmni_seq_shift()	IPCMNI_SHIFT
47 #define IPCMNI_IDX_MASK		((1 << IPCMNI_SHIFT) - 1)
48 #endif /* CONFIG_SYSVIPC_SYSCTL */
49 
50 void sem_init(void);
51 void msg_init(void);
52 void shm_init(void);
53 
54 struct ipc_namespace;
55 struct pid_namespace;
56 
57 #ifdef CONFIG_POSIX_MQUEUE
58 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
59 extern void mq_put_mnt(struct ipc_namespace *ns);
60 #else
mq_clear_sbinfo(struct ipc_namespace * ns)61 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
mq_put_mnt(struct ipc_namespace * ns)62 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
63 #endif
64 
65 #ifdef CONFIG_SYSVIPC
66 void sem_init_ns(struct ipc_namespace *ns);
67 void msg_init_ns(struct ipc_namespace *ns);
68 void shm_init_ns(struct ipc_namespace *ns);
69 
70 void sem_exit_ns(struct ipc_namespace *ns);
71 void msg_exit_ns(struct ipc_namespace *ns);
72 void shm_exit_ns(struct ipc_namespace *ns);
73 #else
sem_init_ns(struct ipc_namespace * ns)74 static inline void sem_init_ns(struct ipc_namespace *ns) { }
msg_init_ns(struct ipc_namespace * ns)75 static inline void msg_init_ns(struct ipc_namespace *ns) { }
shm_init_ns(struct ipc_namespace * ns)76 static inline void shm_init_ns(struct ipc_namespace *ns) { }
77 
sem_exit_ns(struct ipc_namespace * ns)78 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
msg_exit_ns(struct ipc_namespace * ns)79 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
shm_exit_ns(struct ipc_namespace * ns)80 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
81 #endif
82 
83 /*
84  * Structure that holds the parameters needed by the ipc operations
85  * (see after)
86  */
87 struct ipc_params {
88 	key_t key;
89 	int flg;
90 	union {
91 		size_t size;	/* for shared memories */
92 		int nsems;	/* for semaphores */
93 	} u;			/* holds the getnew() specific param */
94 };
95 
96 /*
97  * Structure that holds some ipc operations. This structure is used to unify
98  * the calls to sys_msgget(), sys_semget(), sys_shmget()
99  *      . routine to call to create a new ipc object. Can be one of newque,
100  *        newary, newseg
101  *      . routine to call to check permissions for a new ipc object.
102  *        Can be one of security_msg_associate, security_sem_associate,
103  *        security_shm_associate
104  *      . routine to call for an extra check if needed
105  */
106 struct ipc_ops {
107 	int (*getnew)(struct ipc_namespace *, struct ipc_params *);
108 	int (*associate)(struct kern_ipc_perm *, int);
109 	int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
110 };
111 
112 struct seq_file;
113 struct ipc_ids;
114 
115 void ipc_init_ids(struct ipc_ids *ids);
116 #ifdef CONFIG_PROC_FS
117 void __init ipc_init_proc_interface(const char *path, const char *header,
118 		int ids, int (*show)(struct seq_file *, void *));
119 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
120 #else
121 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
122 #endif
123 
124 #define IPC_SEM_IDS	0
125 #define IPC_MSG_IDS	1
126 #define IPC_SHM_IDS	2
127 
128 #define ipcid_to_idx(id)  ((id) & IPCMNI_IDX_MASK)
129 #define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
130 #define ipcid_seq_max()	  (INT_MAX >> ipcmni_seq_shift())
131 
132 /* must be called with ids->rwsem acquired for writing */
133 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
134 
135 /* must be called with both locks acquired. */
136 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
137 
138 /* must be called with both locks acquired. */
139 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
140 
141 /* must be called with ipcp locked */
142 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
143 
144 /**
145  * ipc_get_maxidx - get the highest assigned index
146  * @ids: ipc identifier set
147  *
148  * Called with ipc_ids.rwsem held for reading.
149  */
ipc_get_maxidx(struct ipc_ids * ids)150 static inline int ipc_get_maxidx(struct ipc_ids *ids)
151 {
152 	if (ids->in_use == 0)
153 		return -1;
154 
155 	if (ids->in_use == ipc_mni)
156 		return ipc_mni - 1;
157 
158 	return ids->max_idx;
159 }
160 
161 /*
162  * For allocation that need to be freed by RCU.
163  * Objects are reference counted, they start with reference count 1.
164  * getref increases the refcount, the putref call that reduces the recount
165  * to 0 schedules the rcu destruction. Caller must guarantee locking.
166  *
167  * refcount is initialized by ipc_addid(), before that point call_rcu()
168  * must be used.
169  */
170 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
171 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
172 			void (*func)(struct rcu_head *head));
173 
174 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
175 
176 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
177 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
178 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
179 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
180 					     struct ipc_ids *ids, int id, int cmd,
181 					     struct ipc64_perm *perm, int extra_perm);
182 
ipc_update_pid(struct pid ** pos,struct pid * pid)183 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
184 {
185 	struct pid *old = *pos;
186 	if (old != pid) {
187 		*pos = get_pid(pid);
188 		put_pid(old);
189 	}
190 }
191 
192 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
193 int ipc_parse_version(int *cmd);
194 #endif
195 
196 extern void free_msg(struct msg_msg *msg);
197 extern struct msg_msg *load_msg(const void __user *src, size_t len);
198 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
199 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
200 
ipc_checkid(struct kern_ipc_perm * ipcp,int id)201 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
202 {
203 	return ipcid_to_seqx(id) != ipcp->seq;
204 }
205 
ipc_lock_object(struct kern_ipc_perm * perm)206 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
207 {
208 	spin_lock(&perm->lock);
209 }
210 
ipc_unlock_object(struct kern_ipc_perm * perm)211 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
212 {
213 	spin_unlock(&perm->lock);
214 }
215 
ipc_assert_locked_object(struct kern_ipc_perm * perm)216 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
217 {
218 	assert_spin_locked(&perm->lock);
219 }
220 
ipc_unlock(struct kern_ipc_perm * perm)221 static inline void ipc_unlock(struct kern_ipc_perm *perm)
222 {
223 	ipc_unlock_object(perm);
224 	rcu_read_unlock();
225 }
226 
227 /*
228  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
229  * where the respective ipc_ids.rwsem is not being held down.
230  * Checks whether the ipc object is still around or if it's gone already, as
231  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
232  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
233  * checkpoint case at sys_semtimedop() as noted in code commentary.
234  */
ipc_valid_object(struct kern_ipc_perm * perm)235 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
236 {
237 	return !perm->deleted;
238 }
239 
240 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
241 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
242 			const struct ipc_ops *ops, struct ipc_params *params);
243 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
244 		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
245 
sem_check_semmni(struct ipc_namespace * ns)246 static inline int sem_check_semmni(struct ipc_namespace *ns) {
247 	/*
248 	 * Check semmni range [0, ipc_mni]
249 	 * semmni is the last element of sem_ctls[4] array
250 	 */
251 	return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
252 		? -ERANGE : 0;
253 }
254 
255 #ifdef CONFIG_COMPAT
256 #include <linux/compat.h>
257 struct compat_ipc_perm {
258 	key_t key;
259 	__compat_uid_t uid;
260 	__compat_gid_t gid;
261 	__compat_uid_t cuid;
262 	__compat_gid_t cgid;
263 	compat_mode_t mode;
264 	unsigned short seq;
265 };
266 
267 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
268 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
269 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
270 int get_compat_ipc64_perm(struct ipc64_perm *,
271 			  struct compat_ipc64_perm __user *);
272 
compat_ipc_parse_version(int * cmd)273 static inline int compat_ipc_parse_version(int *cmd)
274 {
275 	int version = *cmd & IPC_64;
276 	*cmd &= ~IPC_64;
277 	return version;
278 }
279 
280 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
281 long compat_ksys_old_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_old_shmctl(int shmid, int cmd, void __user *uptr);
287 
288 #endif
289 
290 #endif
291