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 #include <linux/pid.h>
18
19 /*
20 * The IPC ID contains 2 separate numbers - index and sequence number.
21 * By default,
22 * bits 0-14: index (32k, 15 bits)
23 * bits 15-30: sequence number (64k, 16 bits)
24 *
25 * When IPCMNI extension mode is turned on, the composition changes:
26 * bits 0-23: index (16M, 24 bits)
27 * bits 24-30: sequence number (128, 7 bits)
28 */
29 #define IPCMNI_SHIFT 15
30 #define IPCMNI_EXTEND_SHIFT 24
31 #define IPCMNI_EXTEND_MIN_CYCLE (RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE)
32 #define IPCMNI (1 << IPCMNI_SHIFT)
33 #define IPCMNI_EXTEND (1 << IPCMNI_EXTEND_SHIFT)
34
35 #ifdef CONFIG_SYSVIPC_SYSCTL
36 extern int ipc_mni;
37 extern int ipc_mni_shift;
38 extern int ipc_min_cycle;
39
40 #define ipcmni_seq_shift() ipc_mni_shift
41 #define IPCMNI_IDX_MASK ((1 << ipc_mni_shift) - 1)
42
43 #else /* CONFIG_SYSVIPC_SYSCTL */
44
45 #define ipc_mni IPCMNI
46 #define ipc_min_cycle ((int)RADIX_TREE_MAP_SIZE)
47 #define ipcmni_seq_shift() IPCMNI_SHIFT
48 #define IPCMNI_IDX_MASK ((1 << IPCMNI_SHIFT) - 1)
49 #endif /* CONFIG_SYSVIPC_SYSCTL */
50
51 void sem_init(void);
52 void msg_init(void);
53 void shm_init(void);
54
55 struct ipc_namespace;
56 struct pid_namespace;
57
58 #ifdef CONFIG_POSIX_MQUEUE
59 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
60 #else
61 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
62 #endif
63
64 #ifdef CONFIG_SYSVIPC
65 void sem_init_ns(struct ipc_namespace *ns);
66 int msg_init_ns(struct ipc_namespace *ns);
67 void shm_init_ns(struct ipc_namespace *ns);
68
69 void sem_exit_ns(struct ipc_namespace *ns);
70 void msg_exit_ns(struct ipc_namespace *ns);
71 void shm_exit_ns(struct ipc_namespace *ns);
72 #else
73 static inline void sem_init_ns(struct ipc_namespace *ns) { }
74 static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
75 static inline void shm_init_ns(struct ipc_namespace *ns) { }
76
77 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
78 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
79 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
80 #endif
81
82 /*
83 * Structure that holds the parameters needed by the ipc operations
84 * (see after)
85 */
86 struct ipc_params {
87 key_t key;
88 int flg;
89 union {
90 size_t size; /* for shared memories */
91 int nsems; /* for semaphores */
92 } u; /* holds the getnew() specific param */
93 };
94
95 /*
96 * Structure that holds some ipc operations. This structure is used to unify
97 * the calls to sys_msgget(), sys_semget(), sys_shmget()
98 * . routine to call to create a new ipc object. Can be one of newque,
99 * newary, newseg
100 * . routine to call to check permissions for a new ipc object.
101 * Can be one of security_msg_associate, security_sem_associate,
102 * security_shm_associate
103 * . routine to call for an extra check if needed
104 */
105 struct ipc_ops {
106 int (*getnew)(struct ipc_namespace *, struct ipc_params *);
107 int (*associate)(struct kern_ipc_perm *, int);
108 int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
109 };
110
111 struct seq_file;
112 struct ipc_ids;
113
114 void ipc_init_ids(struct ipc_ids *ids);
115 #ifdef CONFIG_PROC_FS
116 void __init ipc_init_proc_interface(const char *path, const char *header,
117 int ids, int (*show)(struct seq_file *, void *));
118 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *);
119 #else
120 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
121 #endif
122
123 #define IPC_SEM_IDS 0
124 #define IPC_MSG_IDS 1
125 #define IPC_SHM_IDS 2
126
127 #define ipcid_to_idx(id) ((id) & IPCMNI_IDX_MASK)
128 #define ipcid_to_seqx(id) ((id) >> ipcmni_seq_shift())
129 #define ipcid_seq_max() (INT_MAX >> ipcmni_seq_shift())
130
131 /* must be called with ids->rwsem acquired for writing */
132 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
133
134 /* must be called with both locks acquired. */
135 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
136
137 /* must be called with both locks acquired. */
138 void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
139
140 /* must be called with ipcp locked */
141 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
142
143 /**
144 * ipc_get_maxidx - get the highest assigned index
145 * @ids: ipc identifier set
146 *
147 * The function returns the highest assigned index for @ids. The function
148 * doesn't scan the idr tree, it uses a cached value.
149 *
150 * Called with ipc_ids.rwsem held for reading.
151 */
152 static inline int ipc_get_maxidx(struct ipc_ids *ids)
153 {
154 if (ids->in_use == 0)
155 return -1;
156
157 if (ids->in_use == ipc_mni)
158 return ipc_mni - 1;
159
160 return ids->max_idx;
161 }
162
163 /*
164 * For allocation that need to be freed by RCU.
165 * Objects are reference counted, they start with reference count 1.
166 * getref increases the refcount, the putref call that reduces the recount
167 * to 0 schedules the rcu destruction. Caller must guarantee locking.
168 *
169 * refcount is initialized by ipc_addid(), before that point call_rcu()
170 * must be used.
171 */
172 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
173 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
174 void (*func)(struct rcu_head *head));
175
176 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
177
178 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
179 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
180 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
181 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
182 struct ipc_ids *ids, int id, int cmd,
183 struct ipc64_perm *perm, int extra_perm);
184
185 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
186 {
187 struct pid *old = *pos;
188 if (old != pid) {
189 *pos = get_pid(pid);
190 put_pid(old);
191 }
192 }
193
194 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
195 int ipc_parse_version(int *cmd);
196 #endif
197
198 extern void free_msg(struct msg_msg *msg);
199 extern struct msg_msg *load_msg(const void __user *src, size_t len);
200 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
201 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
202
203 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
204 {
205 return ipcid_to_seqx(id) != ipcp->seq;
206 }
207
208 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
209 {
210 spin_lock(&perm->lock);
211 }
212
213 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
214 {
215 spin_unlock(&perm->lock);
216 }
217
218 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
219 {
220 assert_spin_locked(&perm->lock);
221 }
222
223 static inline void ipc_unlock(struct kern_ipc_perm *perm)
224 {
225 ipc_unlock_object(perm);
226 rcu_read_unlock();
227 }
228
229 /*
230 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
231 * where the respective ipc_ids.rwsem is not being held down.
232 * Checks whether the ipc object is still around or if it's gone already, as
233 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
234 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
235 * checkpoint case at sys_semtimedop() as noted in code commentary.
236 */
237 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
238 {
239 return !perm->deleted;
240 }
241
242 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
243 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
244 const struct ipc_ops *ops, struct ipc_params *params);
245 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
246 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
247
248 static inline int sem_check_semmni(struct ipc_namespace *ns) {
249 /*
250 * Check semmni range [0, ipc_mni]
251 * semmni is the last element of sem_ctls[4] array
252 */
253 return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
254 ? -ERANGE : 0;
255 }
256
257 #ifdef CONFIG_COMPAT
258 #include <linux/compat.h>
259 struct compat_ipc_perm {
260 key_t key;
261 __compat_uid_t uid;
262 __compat_gid_t gid;
263 __compat_uid_t cuid;
264 __compat_gid_t cgid;
265 compat_mode_t mode;
266 unsigned short seq;
267 };
268
269 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
270 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
271 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
272 int get_compat_ipc64_perm(struct ipc64_perm *,
273 struct compat_ipc64_perm __user *);
274
275 static inline int compat_ipc_parse_version(int *cmd)
276 {
277 int version = *cmd & IPC_64;
278 *cmd &= ~IPC_64;
279 return version;
280 }
281
282 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
283 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
284 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
285 compat_long_t msgtyp, int msgflg);
286 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
287 compat_ssize_t msgsz, int msgflg);
288 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
289
290 #endif
291
292 #endif
293
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