util.h revision b2441318
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
17#define SEQ_MULTIPLIER	(IPCMNI)
18
19int sem_init(void);
20int msg_init(void);
21void shm_init(void);
22
23struct ipc_namespace;
24
25#ifdef CONFIG_POSIX_MQUEUE
26extern void mq_clear_sbinfo(struct ipc_namespace *ns);
27extern void mq_put_mnt(struct ipc_namespace *ns);
28#else
29static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
30static inline void mq_put_mnt(struct ipc_namespace *ns) { }
31#endif
32
33#ifdef CONFIG_SYSVIPC
34int sem_init_ns(struct ipc_namespace *ns);
35int msg_init_ns(struct ipc_namespace *ns);
36int shm_init_ns(struct ipc_namespace *ns);
37
38void sem_exit_ns(struct ipc_namespace *ns);
39void msg_exit_ns(struct ipc_namespace *ns);
40void shm_exit_ns(struct ipc_namespace *ns);
41#else
42static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
43static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
44static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
45
46static inline void sem_exit_ns(struct ipc_namespace *ns) { }
47static inline void msg_exit_ns(struct ipc_namespace *ns) { }
48static inline void shm_exit_ns(struct ipc_namespace *ns) { }
49#endif
50
51/*
52 * Structure that holds the parameters needed by the ipc operations
53 * (see after)
54 */
55struct ipc_params {
56	key_t key;
57	int flg;
58	union {
59		size_t size;	/* for shared memories */
60		int nsems;	/* for semaphores */
61	} u;			/* holds the getnew() specific param */
62};
63
64/*
65 * Structure that holds some ipc operations. This structure is used to unify
66 * the calls to sys_msgget(), sys_semget(), sys_shmget()
67 *      . routine to call to create a new ipc object. Can be one of newque,
68 *        newary, newseg
69 *      . routine to call to check permissions for a new ipc object.
70 *        Can be one of security_msg_associate, security_sem_associate,
71 *        security_shm_associate
72 *      . routine to call for an extra check if needed
73 */
74struct ipc_ops {
75	int (*getnew)(struct ipc_namespace *, struct ipc_params *);
76	int (*associate)(struct kern_ipc_perm *, int);
77	int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
78};
79
80struct seq_file;
81struct ipc_ids;
82
83int ipc_init_ids(struct ipc_ids *);
84#ifdef CONFIG_PROC_FS
85void __init ipc_init_proc_interface(const char *path, const char *header,
86		int ids, int (*show)(struct seq_file *, void *));
87#else
88#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
89#endif
90
91#define IPC_SEM_IDS	0
92#define IPC_MSG_IDS	1
93#define IPC_SHM_IDS	2
94
95#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
96#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
97#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
98
99/* must be called with ids->rwsem acquired for writing */
100int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
101
102/* must be called with ids->rwsem acquired for reading */
103int ipc_get_maxid(struct ipc_ids *);
104
105/* must be called with both locks acquired. */
106void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
107
108/* must be called with both locks acquired. */
109void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
110
111/* must be called with ipcp locked */
112int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
113
114/*
115 * For allocation that need to be freed by RCU.
116 * Objects are reference counted, they start with reference count 1.
117 * getref increases the refcount, the putref call that reduces the recount
118 * to 0 schedules the rcu destruction. Caller must guarantee locking.
119 *
120 * refcount is initialized by ipc_addid(), before that point call_rcu()
121 * must be used.
122 */
123int ipc_rcu_getref(struct kern_ipc_perm *ptr);
124void ipc_rcu_putref(struct kern_ipc_perm *ptr,
125			void (*func)(struct rcu_head *head));
126
127struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
128struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
129
130void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
131void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
132int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
133struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
134					     struct ipc_ids *ids, int id, int cmd,
135					     struct ipc64_perm *perm, int extra_perm);
136
137#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
138/* On IA-64, we always use the "64-bit version" of the IPC structures.  */
139# define ipc_parse_version(cmd)	IPC_64
140#else
141int ipc_parse_version(int *cmd);
142#endif
143
144extern void free_msg(struct msg_msg *msg);
145extern struct msg_msg *load_msg(const void __user *src, size_t len);
146extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
147extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
148
149static inline int ipc_buildid(int id, int seq)
150{
151	return SEQ_MULTIPLIER * seq + id;
152}
153
154static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
155{
156	return uid / SEQ_MULTIPLIER != ipcp->seq;
157}
158
159static inline void ipc_lock_object(struct kern_ipc_perm *perm)
160{
161	spin_lock(&perm->lock);
162}
163
164static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
165{
166	spin_unlock(&perm->lock);
167}
168
169static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
170{
171	assert_spin_locked(&perm->lock);
172}
173
174static inline void ipc_unlock(struct kern_ipc_perm *perm)
175{
176	ipc_unlock_object(perm);
177	rcu_read_unlock();
178}
179
180/*
181 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
182 * where the respective ipc_ids.rwsem is not being held down.
183 * Checks whether the ipc object is still around or if it's gone already, as
184 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
185 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
186 * checkpoint case at sys_semtimedop() as noted in code commentary.
187 */
188static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
189{
190	return !perm->deleted;
191}
192
193struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
194int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
195			const struct ipc_ops *ops, struct ipc_params *params);
196void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
197		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
198
199#ifdef CONFIG_COMPAT
200#include <linux/compat.h>
201struct compat_ipc_perm {
202	key_t key;
203	__compat_uid_t uid;
204	__compat_gid_t gid;
205	__compat_uid_t cuid;
206	__compat_gid_t cgid;
207	compat_mode_t mode;
208	unsigned short seq;
209};
210
211void to_compat_ipc_perm(struct compat_ipc_perm *, struct ipc64_perm *);
212void to_compat_ipc64_perm(struct compat_ipc64_perm *, struct ipc64_perm *);
213int get_compat_ipc_perm(struct ipc64_perm *, struct compat_ipc_perm __user *);
214int get_compat_ipc64_perm(struct ipc64_perm *,
215			  struct compat_ipc64_perm __user *);
216
217static inline int compat_ipc_parse_version(int *cmd)
218{
219#ifdef	CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
220	int version = *cmd & IPC_64;
221	*cmd &= ~IPC_64;
222	return version;
223#else
224	return IPC_64;
225#endif
226}
227#endif
228#endif
229