blob: 51f7ca58ac6742989c61c0e0fc8d73bc7eab6bf7
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 |
28 | static inline void mq_clear_sbinfo(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 |
41 | static inline void sem_init_ns(struct ipc_namespace *ns) { } |
42 | static inline void msg_init_ns(struct ipc_namespace *ns) { } |
43 | static inline void shm_init_ns(struct ipc_namespace *ns) { } |
44 | |
45 | static inline void sem_exit_ns(struct ipc_namespace *ns) { } |
46 | static inline void msg_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); |
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_idr(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 | |
158 | static inline int ipc_buildid(int id, int seq) |
159 | { |
160 | return SEQ_MULTIPLIER * seq + id; |
161 | } |
162 | |
163 | static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid) |
164 | { |
165 | return uid / SEQ_MULTIPLIER != ipcp->seq; |
166 | } |
167 | |
168 | static inline void ipc_lock_object(struct kern_ipc_perm *perm) |
169 | { |
170 | spin_lock(&perm->lock); |
171 | } |
172 | |
173 | static inline void ipc_unlock_object(struct kern_ipc_perm *perm) |
174 | { |
175 | spin_unlock(&perm->lock); |
176 | } |
177 | |
178 | static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm) |
179 | { |
180 | assert_spin_locked(&perm->lock); |
181 | } |
182 | |
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 | */ |
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 |