xref: /openbmc/linux/ipc/util.h (revision da27f796)
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 #else
mq_clear_sbinfo(struct ipc_namespace * ns)60 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
61 #endif
62 
63 #ifdef CONFIG_SYSVIPC
64 void sem_init_ns(struct ipc_namespace *ns);
65 int msg_init_ns(struct ipc_namespace *ns);
66 void shm_init_ns(struct ipc_namespace *ns);
67 
68 void sem_exit_ns(struct ipc_namespace *ns);
69 void msg_exit_ns(struct ipc_namespace *ns);
70 void shm_exit_ns(struct ipc_namespace *ns);
71 #else
sem_init_ns(struct ipc_namespace * ns)72 static inline void sem_init_ns(struct ipc_namespace *ns) { }
msg_init_ns(struct ipc_namespace * ns)73 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
shm_init_ns(struct ipc_namespace * ns)74 static inline void shm_init_ns(struct ipc_namespace *ns) { }
75 
sem_exit_ns(struct ipc_namespace * ns)76 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
msg_exit_ns(struct ipc_namespace * ns)77 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
shm_exit_ns(struct ipc_namespace * ns)78 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
79 #endif
80 
81 /*
82  * Structure that holds the parameters needed by the ipc operations
83  * (see after)
84  */
85 struct ipc_params {
86 	key_t key;
87 	int flg;
88 	union {
89 		size_t size;	/* for shared memories */
90 		int nsems;	/* for semaphores */
91 	} u;			/* holds the getnew() specific param */
92 };
93 
94 /*
95  * Structure that holds some ipc operations. This structure is used to unify
96  * the calls to sys_msgget(), sys_semget(), sys_shmget()
97  *      . routine to call to create a new ipc object. Can be one of newque,
98  *        newary, newseg
99  *      . routine to call to check permissions for a new ipc object.
100  *        Can be one of security_msg_associate, security_sem_associate,
101  *        security_shm_associate
102  *      . routine to call for an extra check if needed
103  */
104 struct ipc_ops {
105 	int (*getnew)(struct ipc_namespace *, struct ipc_params *);
106 	int (*associate)(struct kern_ipc_perm *, int);
107 	int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
108 };
109 
110 struct seq_file;
111 struct ipc_ids;
112 
113 void ipc_init_ids(struct ipc_ids *ids);
114 #ifdef CONFIG_PROC_FS
115 void __init ipc_init_proc_interface(const char *path, const char *header,
116 		int ids, int (*show)(struct seq_file *, void *));
117 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
118 #else
119 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
120 #endif
121 
122 #define IPC_SEM_IDS	0
123 #define IPC_MSG_IDS	1
124 #define IPC_SHM_IDS	2
125 
126 #define ipcid_to_idx(id)  ((id) & IPCMNI_IDX_MASK)
127 #define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
128 #define ipcid_seq_max()	  (INT_MAX >> ipcmni_seq_shift())
129 
130 /* must be called with ids->rwsem acquired for writing */
131 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
132 
133 /* must be called with both locks acquired. */
134 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
135 
136 /* must be called with both locks acquired. */
137 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
138 
139 /* must be called with ipcp locked */
140 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
141 
142 /**
143  * ipc_get_maxidx - get the highest assigned index
144  * @ids: ipc identifier set
145  *
146  * The function returns the highest assigned index for @ids. The function
147  * doesn't scan the idr tree, it uses a cached value.
148  *
149  * Called with ipc_ids.rwsem held for reading.
150  */
ipc_get_maxidx(struct ipc_ids * ids)151 static inline int ipc_get_maxidx(struct ipc_ids *ids)
152 {
153 	if (ids->in_use == 0)
154 		return -1;
155 
156 	if (ids->in_use == ipc_mni)
157 		return ipc_mni - 1;
158 
159 	return ids->max_idx;
160 }
161 
162 /*
163  * For allocation that need to be freed by RCU.
164  * Objects are reference counted, they start with reference count 1.
165  * getref increases the refcount, the putref call that reduces the recount
166  * to 0 schedules the rcu destruction. Caller must guarantee locking.
167  *
168  * refcount is initialized by ipc_addid(), before that point call_rcu()
169  * must be used.
170  */
171 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
172 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
173 			void (*func)(struct rcu_head *head));
174 
175 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
176 
177 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
178 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
179 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
180 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
181 					     struct ipc_ids *ids, int id, int cmd,
182 					     struct ipc64_perm *perm, int extra_perm);
183 
ipc_update_pid(struct pid ** pos,struct pid * pid)184 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
185 {
186 	struct pid *old = *pos;
187 	if (old != pid) {
188 		*pos = get_pid(pid);
189 		put_pid(old);
190 	}
191 }
192 
193 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
194 int ipc_parse_version(int *cmd);
195 #endif
196 
197 extern void free_msg(struct msg_msg *msg);
198 extern struct msg_msg *load_msg(const void __user *src, size_t len);
199 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
200 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
201 
ipc_checkid(struct kern_ipc_perm * ipcp,int id)202 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
203 {
204 	return ipcid_to_seqx(id) != ipcp->seq;
205 }
206 
ipc_lock_object(struct kern_ipc_perm * perm)207 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
208 {
209 	spin_lock(&perm->lock);
210 }
211 
ipc_unlock_object(struct kern_ipc_perm * perm)212 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
213 {
214 	spin_unlock(&perm->lock);
215 }
216 
ipc_assert_locked_object(struct kern_ipc_perm * perm)217 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
218 {
219 	assert_spin_locked(&perm->lock);
220 }
221 
ipc_unlock(struct kern_ipc_perm * perm)222 static inline void ipc_unlock(struct kern_ipc_perm *perm)
223 {
224 	ipc_unlock_object(perm);
225 	rcu_read_unlock();
226 }
227 
228 /*
229  * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
230  * where the respective ipc_ids.rwsem is not being held down.
231  * Checks whether the ipc object is still around or if it's gone already, as
232  * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
233  * Needs to be called with kern_ipc_perm.lock held -- exception made for one
234  * checkpoint case at sys_semtimedop() as noted in code commentary.
235  */
ipc_valid_object(struct kern_ipc_perm * perm)236 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
237 {
238 	return !perm->deleted;
239 }
240 
241 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
242 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
243 			const struct ipc_ops *ops, struct ipc_params *params);
244 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
245 		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
246 
sem_check_semmni(struct ipc_namespace * ns)247 static inline int sem_check_semmni(struct ipc_namespace *ns) {
248 	/*
249 	 * Check semmni range [0, ipc_mni]
250 	 * semmni is the last element of sem_ctls[4] array
251 	 */
252 	return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
253 		? -ERANGE : 0;
254 }
255 
256 #ifdef CONFIG_COMPAT
257 #include <linux/compat.h>
258 struct compat_ipc_perm {
259 	key_t key;
260 	__compat_uid_t uid;
261 	__compat_gid_t gid;
262 	__compat_uid_t cuid;
263 	__compat_gid_t cgid;
264 	compat_mode_t mode;
265 	unsigned short seq;
266 };
267 
268 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
269 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
270 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
271 int get_compat_ipc64_perm(struct ipc64_perm *,
272 			  struct compat_ipc64_perm __user *);
273 
compat_ipc_parse_version(int * cmd)274 static inline int compat_ipc_parse_version(int *cmd)
275 {
276 	int version = *cmd & IPC_64;
277 	*cmd &= ~IPC_64;
278 	return version;
279 }
280 
281 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
282 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
283 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
284 			compat_long_t msgtyp, int msgflg);
285 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
286 		       compat_ssize_t msgsz, int msgflg);
287 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
288 
289 #endif
290 
291 #endif
292