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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 <[email protected]>
7 * namespaces support. 2006 OpenVZ, SWsoft Inc.
8 * Pavel Emelianov <[email protected]>
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
36extern int ipc_mni;
37extern int ipc_mni_shift;
38extern 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
51void sem_init(void);
52void msg_init(void);
53void shm_init(void);
54
55struct ipc_namespace;
56struct pid_namespace;
57
58#ifdef CONFIG_POSIX_MQUEUE
59extern void mq_clear_sbinfo(struct ipc_namespace *ns);
60#else
61static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
62#endif
63
64#ifdef CONFIG_SYSVIPC
65void sem_init_ns(struct ipc_namespace *ns);
66int msg_init_ns(struct ipc_namespace *ns);
67void shm_init_ns(struct ipc_namespace *ns);
68
69void sem_exit_ns(struct ipc_namespace *ns);
70void msg_exit_ns(struct ipc_namespace *ns);
71void shm_exit_ns(struct ipc_namespace *ns);
72#else
73static inline void sem_init_ns(struct ipc_namespace *ns) { }
74static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
75static inline void shm_init_ns(struct ipc_namespace *ns) { }
76
77static inline void sem_exit_ns(struct ipc_namespace *ns) { }
78static inline void msg_exit_ns(struct ipc_namespace *ns) { }
79static 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 */
86struct 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 */
105struct 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
111struct seq_file;
112struct ipc_ids;
113
114void ipc_init_ids(struct ipc_ids *ids);
115#ifdef CONFIG_PROC_FS
116void __init ipc_init_proc_interface(const char *path, const char *header,
117 int ids, int (*show)(struct seq_file *, void *));
118struct 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 */
132int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
133
134/* must be called with both locks acquired. */
135void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
136
137/* must be called with both locks acquired. */
138void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
139
140/* must be called with ipcp locked */
141int 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 */
152static 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 */
172bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
173void ipc_rcu_putref(struct kern_ipc_perm *ptr,
174 void (*func)(struct rcu_head *head));
175
176struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
177
178void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
179void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
180int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
181struct 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
185static 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
195int ipc_parse_version(int *cmd);
196#endif
197
198extern void free_msg(struct msg_msg *msg);
199extern struct msg_msg *load_msg(const void __user *src, size_t len);
200extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
201extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
202
203static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
204{
205 return ipcid_to_seqx(id) != ipcp->seq;
206}
207
208static inline void ipc_lock_object(struct kern_ipc_perm *perm)
209{
210 spin_lock(&perm->lock);
211}
212
213static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
214{
215 spin_unlock(&perm->lock);
216}
217
218static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
219{
220 assert_spin_locked(&perm->lock);
221}
222
223static 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 */
237static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
238{
239 return !perm->deleted;
240}
241
242struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
243int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
244 const struct ipc_ops *ops, struct ipc_params *params);
245void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
246 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
247
248static 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>
259struct 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
269void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
270void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
271int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
272int get_compat_ipc64_perm(struct ipc64_perm *,
273 struct compat_ipc64_perm __user *);
274
275static inline int compat_ipc_parse_version(int *cmd)
276{
277 int version = *cmd & IPC_64;
278 *cmd &= ~IPC_64;
279 return version;
280}
281
282long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
283long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
284long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
285 compat_long_t msgtyp, int msgflg);
286long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
287 compat_ssize_t msgsz, int msgflg);
288long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
289
290#endif
291
292#endif