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 int 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 int msg_init_ns(struct ipc_namespace *ns) { return 0; }
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 * The function returns the highest assigned index for @ids. The function
149 * doesn't scan the idr tree, it uses a cached value.
150 *
151 * Called with ipc_ids.rwsem held for reading.
152 */
ipc_get_maxidx(struct ipc_ids * ids)153 static inline int ipc_get_maxidx(struct ipc_ids *ids)
154 {
155 if (ids->in_use == 0)
156 return -1;
157
158 if (ids->in_use == ipc_mni)
159 return ipc_mni - 1;
160
161 return ids->max_idx;
162 }
163
164 /*
165 * For allocation that need to be freed by RCU.
166 * Objects are reference counted, they start with reference count 1.
167 * getref increases the refcount, the putref call that reduces the recount
168 * to 0 schedules the rcu destruction. Caller must guarantee locking.
169 *
170 * refcount is initialized by ipc_addid(), before that point call_rcu()
171 * must be used.
172 */
173 bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
174 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
175 void (*func)(struct rcu_head *head));
176
177 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
178
179 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
180 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
181 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
182 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
183 struct ipc_ids *ids, int id, int cmd,
184 struct ipc64_perm *perm, int extra_perm);
185
ipc_update_pid(struct pid ** pos,struct pid * pid)186 static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
187 {
188 struct pid *old = *pos;
189 if (old != pid) {
190 *pos = get_pid(pid);
191 put_pid(old);
192 }
193 }
194
195 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
196 int ipc_parse_version(int *cmd);
197 #endif
198
199 extern void free_msg(struct msg_msg *msg);
200 extern struct msg_msg *load_msg(const void __user *src, size_t len);
201 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
202 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
203
ipc_checkid(struct kern_ipc_perm * ipcp,int id)204 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
205 {
206 return ipcid_to_seqx(id) != ipcp->seq;
207 }
208
ipc_lock_object(struct kern_ipc_perm * perm)209 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
210 {
211 spin_lock(&perm->lock);
212 }
213
ipc_unlock_object(struct kern_ipc_perm * perm)214 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
215 {
216 spin_unlock(&perm->lock);
217 }
218
ipc_assert_locked_object(struct kern_ipc_perm * perm)219 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
220 {
221 assert_spin_locked(&perm->lock);
222 }
223
ipc_unlock(struct kern_ipc_perm * perm)224 static inline void ipc_unlock(struct kern_ipc_perm *perm)
225 {
226 ipc_unlock_object(perm);
227 rcu_read_unlock();
228 }
229
230 /*
231 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
232 * where the respective ipc_ids.rwsem is not being held down.
233 * Checks whether the ipc object is still around or if it's gone already, as
234 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
235 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
236 * checkpoint case at sys_semtimedop() as noted in code commentary.
237 */
ipc_valid_object(struct kern_ipc_perm * perm)238 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
239 {
240 return !perm->deleted;
241 }
242
243 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
244 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
245 const struct ipc_ops *ops, struct ipc_params *params);
246 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
247 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
248
sem_check_semmni(struct ipc_namespace * ns)249 static inline int sem_check_semmni(struct ipc_namespace *ns) {
250 /*
251 * Check semmni range [0, ipc_mni]
252 * semmni is the last element of sem_ctls[4] array
253 */
254 return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
255 ? -ERANGE : 0;
256 }
257
258 #ifdef CONFIG_COMPAT
259 #include <linux/compat.h>
260 struct compat_ipc_perm {
261 key_t key;
262 __compat_uid_t uid;
263 __compat_gid_t gid;
264 __compat_uid_t cuid;
265 __compat_gid_t cgid;
266 compat_mode_t mode;
267 unsigned short seq;
268 };
269
270 void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
271 void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
272 int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
273 int get_compat_ipc64_perm(struct ipc64_perm *,
274 struct compat_ipc64_perm __user *);
275
compat_ipc_parse_version(int * cmd)276 static inline int compat_ipc_parse_version(int *cmd)
277 {
278 int version = *cmd & IPC_64;
279 *cmd &= ~IPC_64;
280 return version;
281 }
282
283 long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
284 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
285 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
286 compat_long_t msgtyp, int msgflg);
287 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
288 compat_ssize_t msgsz, int msgflg);
289 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
290
291 #endif
292
293 #endif
294