util.h revision 53dad6d3
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
18void sem_init (void);
19void 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
33void sem_init_ns(struct ipc_namespace *ns);
34void msg_init_ns(struct ipc_namespace *ns);
35void 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 void sem_init_ns(struct ipc_namespace *ns) { }
42static inline void msg_init_ns(struct ipc_namespace *ns) { }
43static inline void shm_init_ns(struct ipc_namespace *ns) { }
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
50struct ipc_rcu {
51	struct rcu_head rcu;
52	atomic_t refcount;
53} ____cacheline_aligned_in_smp;
54
55#define ipc_rcu_to_struct(p)  ((void *)(p+1))
56
57/*
58 * Structure that holds the parameters needed by the ipc operations
59 * (see after)
60 */
61struct ipc_params {
62	key_t key;
63	int flg;
64	union {
65		size_t size;	/* for shared memories */
66		int nsems;	/* for semaphores */
67	} u;			/* holds the getnew() specific param */
68};
69
70/*
71 * Structure that holds some ipc operations. This structure is used to unify
72 * the calls to sys_msgget(), sys_semget(), sys_shmget()
73 *      . routine to call to create a new ipc object. Can be one of newque,
74 *        newary, newseg
75 *      . routine to call to check permissions for a new ipc object.
76 *        Can be one of security_msg_associate, security_sem_associate,
77 *        security_shm_associate
78 *      . routine to call for an extra check if needed
79 */
80struct ipc_ops {
81	int (*getnew) (struct ipc_namespace *, struct ipc_params *);
82	int (*associate) (struct kern_ipc_perm *, int);
83	int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
84};
85
86struct seq_file;
87struct ipc_ids;
88
89void ipc_init_ids(struct ipc_ids *);
90#ifdef CONFIG_PROC_FS
91void __init ipc_init_proc_interface(const char *path, const char *header,
92		int ids, int (*show)(struct seq_file *, void *));
93#else
94#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
95#endif
96
97#define IPC_SEM_IDS	0
98#define IPC_MSG_IDS	1
99#define IPC_SHM_IDS	2
100
101#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
102#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
103
104/* must be called with ids->rwsem acquired for writing */
105int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
106
107/* must be called with ids->rwsem acquired for reading */
108int ipc_get_maxid(struct ipc_ids *);
109
110/* must be called with both locks acquired. */
111void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
112
113/* must be called with ipcp locked */
114int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
115
116/* for rare, potentially huge allocations.
117 * both function can sleep
118 */
119void* ipc_alloc(int size);
120void ipc_free(void* ptr, int size);
121
122/*
123 * For allocation that need to be freed by RCU.
124 * Objects are reference counted, they start with reference count 1.
125 * getref increases the refcount, the putref call that reduces the recount
126 * to 0 schedules the rcu destruction. Caller must guarantee locking.
127 */
128void* ipc_rcu_alloc(int size);
129int ipc_rcu_getref(void *ptr);
130void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head));
131void ipc_rcu_free(struct rcu_head *head);
132
133struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
134struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id);
135
136void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
137void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
138int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
139struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
140					     struct ipc_ids *ids, int id, int cmd,
141					     struct ipc64_perm *perm, int extra_perm);
142
143#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
144  /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
145# define ipc_parse_version(cmd)	IPC_64
146#else
147int ipc_parse_version (int *cmd);
148#endif
149
150extern void free_msg(struct msg_msg *msg);
151extern struct msg_msg *load_msg(const void __user *src, int len);
152extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
153extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
154
155extern void recompute_msgmni(struct ipc_namespace *);
156
157static inline int ipc_buildid(int id, int seq)
158{
159	return SEQ_MULTIPLIER * seq + id;
160}
161
162static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
163{
164	return uid / SEQ_MULTIPLIER != ipcp->seq;
165}
166
167static inline void ipc_lock_object(struct kern_ipc_perm *perm)
168{
169	spin_lock(&perm->lock);
170}
171
172static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
173{
174	spin_unlock(&perm->lock);
175}
176
177static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
178{
179	assert_spin_locked(&perm->lock);
180}
181
182static inline void ipc_unlock(struct kern_ipc_perm *perm)
183{
184	ipc_unlock_object(perm);
185	rcu_read_unlock();
186}
187
188struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
189int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
190			struct ipc_ops *ops, struct ipc_params *params);
191void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
192		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
193#endif
194