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
18 void sem_init(void);
19 void msg_init(void);
20 void shm_init(void);
21
22 struct ipc_namespace;
23
24 #ifdef CONFIG_POSIX_MQUEUE
25 extern void mq_clear_sbinfo(struct ipc_namespace *ns);
26 extern void mq_put_mnt(struct ipc_namespace *ns);
27 #else
mq_clear_sbinfo(struct ipc_namespace * ns)28 static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
mq_put_mnt(struct ipc_namespace * ns)29 static inline void mq_put_mnt(struct ipc_namespace *ns) { }
30 #endif
31
32 #ifdef CONFIG_SYSVIPC
33 void sem_init_ns(struct ipc_namespace *ns);
34 void msg_init_ns(struct ipc_namespace *ns);
35 void shm_init_ns(struct ipc_namespace *ns);
36
37 void sem_exit_ns(struct ipc_namespace *ns);
38 void msg_exit_ns(struct ipc_namespace *ns);
39 void shm_exit_ns(struct ipc_namespace *ns);
40 #else
sem_init_ns(struct ipc_namespace * ns)41 static inline void sem_init_ns(struct ipc_namespace *ns) { }
msg_init_ns(struct ipc_namespace * ns)42 static inline void msg_init_ns(struct ipc_namespace *ns) { }
shm_init_ns(struct ipc_namespace * ns)43 static inline void shm_init_ns(struct ipc_namespace *ns) { }
44
sem_exit_ns(struct ipc_namespace * ns)45 static inline void sem_exit_ns(struct ipc_namespace *ns) { }
msg_exit_ns(struct ipc_namespace * ns)46 static inline void msg_exit_ns(struct ipc_namespace *ns) { }
shm_exit_ns(struct ipc_namespace * ns)47 static inline void shm_exit_ns(struct ipc_namespace *ns) { }
48 #endif
49
50 struct 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 */
61 struct 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 */
80 struct 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
86 struct seq_file;
87 struct ipc_ids;
88
89 void ipc_init_ids(struct ipc_ids *);
90 #ifdef CONFIG_PROC_FS
91 void __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 #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
104
105 /* must be called with ids->rwsem acquired for writing */
106 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
107
108 /* must be called with ids->rwsem acquired for reading */
109 int ipc_get_maxid(struct ipc_ids *);
110
111 /* must be called with both locks acquired. */
112 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
113
114 /* must be called with ipcp locked */
115 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
116
117 /* for rare, potentially huge allocations.
118 * both function can sleep
119 */
120 void *ipc_alloc(int size);
121 void ipc_free(void *ptr, int size);
122
123 /*
124 * For allocation that need to be freed by RCU.
125 * Objects are reference counted, they start with reference count 1.
126 * getref increases the refcount, the putref call that reduces the recount
127 * to 0 schedules the rcu destruction. Caller must guarantee locking.
128 */
129 void *ipc_rcu_alloc(int size);
130 int ipc_rcu_getref(void *ptr);
131 void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head));
132 void ipc_rcu_free(struct rcu_head *head);
133
134 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
135 struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id);
136
137 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
138 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
139 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
140 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
141 struct ipc_ids *ids, int id, int cmd,
142 struct ipc64_perm *perm, int extra_perm);
143
144 #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
145 /* On IA-64, we always use the "64-bit version" of the IPC structures. */
146 # define ipc_parse_version(cmd) IPC_64
147 #else
148 int ipc_parse_version(int *cmd);
149 #endif
150
151 extern void free_msg(struct msg_msg *msg);
152 extern struct msg_msg *load_msg(const void __user *src, size_t len);
153 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
154 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
155
156 extern void recompute_msgmni(struct ipc_namespace *);
157
ipc_buildid(int id,int seq)158 static inline int ipc_buildid(int id, int seq)
159 {
160 return SEQ_MULTIPLIER * seq + id;
161 }
162
ipc_checkid(struct kern_ipc_perm * ipcp,int uid)163 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
164 {
165 return uid / SEQ_MULTIPLIER != ipcp->seq;
166 }
167
ipc_lock_object(struct kern_ipc_perm * perm)168 static inline void ipc_lock_object(struct kern_ipc_perm *perm)
169 {
170 spin_lock(&perm->lock);
171 }
172
ipc_unlock_object(struct kern_ipc_perm * perm)173 static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
174 {
175 spin_unlock(&perm->lock);
176 }
177
ipc_assert_locked_object(struct kern_ipc_perm * perm)178 static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
179 {
180 assert_spin_locked(&perm->lock);
181 }
182
ipc_unlock(struct kern_ipc_perm * perm)183 static inline void ipc_unlock(struct kern_ipc_perm *perm)
184 {
185 ipc_unlock_object(perm);
186 rcu_read_unlock();
187 }
188
189 /*
190 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
191 * where the respective ipc_ids.rwsem is not being held down.
192 * Checks whether the ipc object is still around or if it's gone already, as
193 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
194 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
195 * checkpoint case at sys_semtimedop() as noted in code commentary.
196 */
ipc_valid_object(struct kern_ipc_perm * perm)197 static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
198 {
199 return !perm->deleted;
200 }
201
202 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
203 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
204 const struct ipc_ops *ops, struct ipc_params *params);
205 void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
206 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
207 #endif
208