util.h revision 0cfb6aee
1/*
2 * linux/ipc/util.h
3 * Copyright (C) 1999 Christoph Rohland
4 *
5 * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
6 * namespaces support.      2006 OpenVZ, SWsoft Inc.
7 *                               Pavel Emelianov <xemul@openvz.org>
8 */
9
10#ifndef _IPC_UTIL_H
11#define _IPC_UTIL_H
12
13#include <linux/unistd.h>
14#include <linux/err.h>
15
16#define SEQ_MULTIPLIER	(IPCMNI)
17
18int sem_init(void);
19int msg_init(void);
20void shm_init(void);
21
22struct ipc_namespace;
23
24#ifdef CONFIG_POSIX_MQUEUE
25extern void mq_clear_sbinfo(struct ipc_namespace *ns);
26extern void mq_put_mnt(struct ipc_namespace *ns);
27#else
28static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
29static inline void mq_put_mnt(struct ipc_namespace *ns) { }
30#endif
31
32#ifdef CONFIG_SYSVIPC
33int sem_init_ns(struct ipc_namespace *ns);
34int msg_init_ns(struct ipc_namespace *ns);
35int shm_init_ns(struct ipc_namespace *ns);
36
37void sem_exit_ns(struct ipc_namespace *ns);
38void msg_exit_ns(struct ipc_namespace *ns);
39void shm_exit_ns(struct ipc_namespace *ns);
40#else
41static inline int sem_init_ns(struct ipc_namespace *ns) { return 0; }
42static inline int msg_init_ns(struct ipc_namespace *ns) { return 0; }
43static inline int shm_init_ns(struct ipc_namespace *ns) { return 0; }
44
45static inline void sem_exit_ns(struct ipc_namespace *ns) { }
46static inline void msg_exit_ns(struct ipc_namespace *ns) { }
47static inline void shm_exit_ns(struct ipc_namespace *ns) { }
48#endif
49
50/*
51 * Structure that holds the parameters needed by the ipc operations
52 * (see after)
53 */
54struct ipc_params {
55	key_t key;
56	int flg;
57	union {
58		size_t size;	/* for shared memories */
59		int nsems;	/* for semaphores */
60	} u;			/* holds the getnew() specific param */
61};
62
63/*
64 * Structure that holds some ipc operations. This structure is used to unify
65 * the calls to sys_msgget(), sys_semget(), sys_shmget()
66 *      . routine to call to create a new ipc object. Can be one of newque,
67 *        newary, newseg
68 *      . routine to call to check permissions for a new ipc object.
69 *        Can be one of security_msg_associate, security_sem_associate,
70 *        security_shm_associate
71 *      . routine to call for an extra check if needed
72 */
73struct ipc_ops {
74	int (*getnew)(struct ipc_namespace *, struct ipc_params *);
75	int (*associate)(struct kern_ipc_perm *, int);
76	int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
77};
78
79struct seq_file;
80struct ipc_ids;
81
82int ipc_init_ids(struct ipc_ids *);
83#ifdef CONFIG_PROC_FS
84void __init ipc_init_proc_interface(const char *path, const char *header,
85		int ids, int (*show)(struct seq_file *, void *));
86#else
87#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
88#endif
89
90#define IPC_SEM_IDS	0
91#define IPC_MSG_IDS	1
92#define IPC_SHM_IDS	2
93
94#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
95#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
96#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
97
98/* must be called with ids->rwsem acquired for writing */
99int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
100
101/* must be called with ids->rwsem acquired for reading */
102int ipc_get_maxid(struct ipc_ids *);
103
104/* must be called with both locks acquired. */
105void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
106
107/* must be called with both locks acquired. */
108void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
109
110/* must be called with ipcp locked */
111int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
112
113/*
114 * For allocation that need to be freed by RCU.
115 * Objects are reference counted, they start with reference count 1.
116 * getref increases the refcount, the putref call that reduces the recount
117 * to 0 schedules the rcu destruction. Caller must guarantee locking.
118 *
119 * refcount is initialized by ipc_addid(), before that point call_rcu()
120 * must be used.
121 */
122int ipc_rcu_getref(struct kern_ipc_perm *ptr);
123void ipc_rcu_putref(struct kern_ipc_perm *ptr,
124			void (*func)(struct rcu_head *head));
125
126struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
127struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);
128
129void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
130void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
131int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
132struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
133					     struct ipc_ids *ids, int id, int cmd,
134					     struct ipc64_perm *perm, int extra_perm);
135
136#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
137/* On IA-64, we always use the "64-bit version" of the IPC structures.  */
138# define ipc_parse_version(cmd)	IPC_64
139#else
140int ipc_parse_version(int *cmd);
141#endif
142
143extern void free_msg(struct msg_msg *msg);
144extern struct msg_msg *load_msg(const void __user *src, size_t len);
145extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
146extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
147
148static inline int ipc_buildid(int id, int seq)
149{
150	return SEQ_MULTIPLIER * seq + id;
151}
152
153static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
154{
155	return uid / SEQ_MULTIPLIER != ipcp->seq;
156}
157
158static inline void ipc_lock_object(struct kern_ipc_perm *perm)
159{
160	spin_lock(&perm->lock);
161}
162
163static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
164{
165	spin_unlock(&perm->lock);
166}
167
168static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
169{
170	assert_spin_locked(&perm->lock);
171}
172
173static inline void ipc_unlock(struct kern_ipc_perm *perm)
174{
175	ipc_unlock_object(perm);
176	rcu_read_unlock();
177}
178
179/*
180 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
181 * where the respective ipc_ids.rwsem is not being held down.
182 * Checks whether the ipc object is still around or if it's gone already, as
183 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
184 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
185 * checkpoint case at sys_semtimedop() as noted in code commentary.
186 */
187static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
188{
189	return !perm->deleted;
190}
191
192struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
193int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
194			const struct ipc_ops *ops, struct ipc_params *params);
195void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
196		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
197#endif
198