Line data Source code
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
61 : static inline void mq_clear_sbinfo(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
74 : static inline void sem_init_ns(struct ipc_namespace *ns) { }
75 : static inline void msg_init_ns(struct ipc_namespace *ns) { }
76 : static inline void shm_init_ns(struct ipc_namespace *ns) { }
77 :
78 : static inline void sem_exit_ns(struct ipc_namespace *ns) { }
79 : static inline void msg_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 : */
150 0 : static inline int ipc_get_maxidx(struct ipc_ids *ids)
151 : {
152 0 : if (ids->in_use == 0)
153 : return -1;
154 :
155 0 : if (ids->in_use == ipc_mni)
156 0 : return ipc_mni - 1;
157 :
158 0 : 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 :
183 0 : static inline void ipc_update_pid(struct pid **pos, struct pid *pid)
184 : {
185 0 : struct pid *old = *pos;
186 0 : if (old != pid) {
187 0 : *pos = get_pid(pid);
188 0 : put_pid(old);
189 : }
190 0 : }
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 :
201 0 : static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
202 : {
203 0 : return ipcid_to_seqx(id) != ipcp->seq;
204 : }
205 :
206 0 : static inline void ipc_lock_object(struct kern_ipc_perm *perm)
207 : {
208 0 : spin_lock(&perm->lock);
209 0 : }
210 :
211 0 : static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
212 : {
213 0 : spin_unlock(&perm->lock);
214 0 : }
215 :
216 0 : static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
217 : {
218 0 : assert_spin_locked(&perm->lock);
219 0 : }
220 :
221 0 : static inline void ipc_unlock(struct kern_ipc_perm *perm)
222 : {
223 0 : ipc_unlock_object(perm);
224 0 : rcu_read_unlock();
225 0 : }
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 : */
235 0 : static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
236 : {
237 0 : 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 :
246 0 : 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 0 : return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > ipc_mni))
252 0 : ? -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 :
273 0 : static inline int compat_ipc_parse_version(int *cmd)
274 : {
275 0 : int version = *cmd & IPC_64;
276 0 : *cmd &= ~IPC_64;
277 0 : 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
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