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
35extern int ipc_mni;
36extern int ipc_mni_shift;
37extern 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
50void sem_init(void);
51void msg_init(void);
52void shm_init(void);
53
54struct ipc_namespace;
55struct pid_namespace;
56
57#ifdef CONFIG_POSIX_MQUEUE
58extern void mq_clear_sbinfo(struct ipc_namespace *ns);
59extern void mq_put_mnt(struct ipc_namespace *ns);
60#else
61static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
62static inline void mq_put_mnt(struct ipc_namespace *ns) { }
63#endif
64
65#ifdef CONFIG_SYSVIPC
66void sem_init_ns(struct ipc_namespace *ns);
67void msg_init_ns(struct ipc_namespace *ns);
68void shm_init_ns(struct ipc_namespace *ns);
69
70void sem_exit_ns(struct ipc_namespace *ns);
71void msg_exit_ns(struct ipc_namespace *ns);
72void shm_exit_ns(struct ipc_namespace *ns);
73#else
74static inline void sem_init_ns(struct ipc_namespace *ns) { }
75static inline void msg_init_ns(struct ipc_namespace *ns) { }
76static inline void shm_init_ns(struct ipc_namespace *ns) { }
77
78static inline void sem_exit_ns(struct ipc_namespace *ns) { }
79static inline void msg_exit_ns(struct ipc_namespace *ns) { }
80static 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 */
87struct 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 */
106struct 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
112struct seq_file;
113struct ipc_ids;
114
115void ipc_init_ids(struct ipc_ids *ids);
116#ifdef CONFIG_PROC_FS
117void __init ipc_init_proc_interface(const char *path, const char *header,
118		int ids, int (*show)(struct seq_file *, void *));
119struct 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 */
133int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
134
135/* must be called with both locks acquired. */
136void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
137
138/* must be called with both locks acquired. */
139void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
140
141/* must be called with ipcp locked */
142int 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 */
153static 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 */
173bool ipc_rcu_getref(struct kern_ipc_perm *ptr);
174void ipc_rcu_putref(struct kern_ipc_perm *ptr,
175			void (*func)(struct rcu_head *head));
176
177struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
178
179void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
180void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
181int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
182struct 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
186static 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
196int ipc_parse_version(int *cmd);
197#endif
198
199extern void free_msg(struct msg_msg *msg);
200extern struct msg_msg *load_msg(const void __user *src, size_t len);
201extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
202extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
203
204static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int id)
205{
206	return ipcid_to_seqx(id) != ipcp->seq;
207}
208
209static inline void ipc_lock_object(struct kern_ipc_perm *perm)
210{
211	spin_lock(&perm->lock);
212}
213
214static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
215{
216	spin_unlock(&perm->lock);
217}
218
219static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
220{
221	assert_spin_locked(&perm->lock);
222}
223
224static 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 */
238static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
239{
240	return !perm->deleted;
241}
242
243struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
244int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
245			const struct ipc_ops *ops, struct ipc_params *params);
246void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
247		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
248
249static 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>
260struct 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
270void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
271void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
272int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
273int get_compat_ipc64_perm(struct ipc64_perm *,
274			  struct compat_ipc64_perm __user *);
275
276static inline int compat_ipc_parse_version(int *cmd)
277{
278	int version = *cmd & IPC_64;
279	*cmd &= ~IPC_64;
280	return version;
281}
282
283long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg);
284long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr);
285long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
286			compat_long_t msgtyp, int msgflg);
287long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
288		       compat_ssize_t msgsz, int msgflg);
289long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr);
290
291#endif
292
293#endif
294