xref: /openbmc/linux/ipc/util.h (revision 643d1f7f)
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/idr.h>
14 #include <linux/err.h>
15 
16 #define USHRT_MAX 0xffff
17 #define SEQ_MULTIPLIER	(IPCMNI)
18 
19 void sem_init (void);
20 void msg_init (void);
21 void shm_init (void);
22 
23 int sem_init_ns(struct ipc_namespace *ns);
24 int msg_init_ns(struct ipc_namespace *ns);
25 int shm_init_ns(struct ipc_namespace *ns);
26 
27 void sem_exit_ns(struct ipc_namespace *ns);
28 void msg_exit_ns(struct ipc_namespace *ns);
29 void shm_exit_ns(struct ipc_namespace *ns);
30 
31 struct ipc_ids {
32 	int in_use;
33 	unsigned short seq;
34 	unsigned short seq_max;
35 	struct rw_semaphore rw_mutex;
36 	struct idr ipcs_idr;
37 };
38 
39 /*
40  * Structure that holds the parameters needed by the ipc operations
41  * (see after)
42  */
43 struct ipc_params {
44 	key_t key;
45 	int flg;
46 	union {
47 		size_t size;	/* for shared memories */
48 		int nsems;	/* for semaphores */
49 	} u;			/* holds the getnew() specific param */
50 };
51 
52 /*
53  * Structure that holds some ipc operations. This structure is used to unify
54  * the calls to sys_msgget(), sys_semget(), sys_shmget()
55  *      . routine to call to create a new ipc object. Can be one of newque,
56  *        newary, newseg
57  *      . routine to call to check permissions for a new ipc object.
58  *        Can be one of security_msg_associate, security_sem_associate,
59  *        security_shm_associate
60  *      . routine to call for an extra check if needed
61  */
62 struct ipc_ops {
63 	int (*getnew) (struct ipc_namespace *, struct ipc_params *);
64 	int (*associate) (struct kern_ipc_perm *, int);
65 	int (*more_checks) (struct kern_ipc_perm *, struct ipc_params *);
66 };
67 
68 struct seq_file;
69 
70 void ipc_init_ids(struct ipc_ids *);
71 #ifdef CONFIG_PROC_FS
72 void __init ipc_init_proc_interface(const char *path, const char *header,
73 		int ids, int (*show)(struct seq_file *, void *));
74 #else
75 #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
76 #endif
77 
78 #define IPC_SEM_IDS	0
79 #define IPC_MSG_IDS	1
80 #define IPC_SHM_IDS	2
81 
82 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
83 
84 /* must be called with ids->rw_mutex acquired for writing */
85 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
86 
87 /* must be called with ids->rw_mutex acquired for reading */
88 int ipc_get_maxid(struct ipc_ids *);
89 
90 /* must be called with both locks acquired. */
91 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
92 
93 /* must be called with ipcp locked */
94 int ipcperms(struct kern_ipc_perm *ipcp, short flg);
95 
96 /* for rare, potentially huge allocations.
97  * both function can sleep
98  */
99 void* ipc_alloc(int size);
100 void ipc_free(void* ptr, int size);
101 
102 /*
103  * For allocation that need to be freed by RCU.
104  * Objects are reference counted, they start with reference count 1.
105  * getref increases the refcount, the putref call that reduces the recount
106  * to 0 schedules the rcu destruction. Caller must guarantee locking.
107  */
108 void* ipc_rcu_alloc(int size);
109 void ipc_rcu_getref(void *ptr);
110 void ipc_rcu_putref(void *ptr);
111 
112 /*
113  * ipc_lock_down: called with rw_mutex held
114  * ipc_lock: called without that lock held
115  */
116 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
117 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
118 
119 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
120 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
121 
122 #if defined(__ia64__) || defined(__x86_64__) || defined(__hppa__) || defined(__XTENSA__)
123   /* On IA-64, we always use the "64-bit version" of the IPC structures.  */
124 # define ipc_parse_version(cmd)	IPC_64
125 #else
126 int ipc_parse_version (int *cmd);
127 #endif
128 
129 extern void free_msg(struct msg_msg *msg);
130 extern struct msg_msg *load_msg(const void __user *src, int len);
131 extern int store_msg(void __user *dest, struct msg_msg *msg, int len);
132 extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *,
133 			struct ipc_ops *, struct ipc_params *);
134 extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
135 			struct ipc_ops *, struct ipc_params *);
136 
137 static inline int ipc_buildid(int id, int seq)
138 {
139 	return SEQ_MULTIPLIER * seq + id;
140 }
141 
142 /*
143  * Must be called with ipcp locked
144  */
145 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
146 {
147 	if (uid / SEQ_MULTIPLIER != ipcp->seq)
148 		return 1;
149 	return 0;
150 }
151 
152 static inline void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
153 {
154 	rcu_read_lock();
155 	spin_lock(&perm->lock);
156 }
157 
158 static inline void ipc_unlock(struct kern_ipc_perm *perm)
159 {
160 	spin_unlock(&perm->lock);
161 	rcu_read_unlock();
162 }
163 
164 static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
165 						int id)
166 {
167 	struct kern_ipc_perm *out;
168 
169 	out = ipc_lock_down(ids, id);
170 	if (IS_ERR(out))
171 		return out;
172 
173 	if (ipc_checkid(out, id)) {
174 		ipc_unlock(out);
175 		return ERR_PTR(-EIDRM);
176 	}
177 
178 	return out;
179 }
180 
181 static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
182 						int id)
183 {
184 	struct kern_ipc_perm *out;
185 
186 	out = ipc_lock(ids, id);
187 	if (IS_ERR(out))
188 		return out;
189 
190 	if (ipc_checkid(out, id)) {
191 		ipc_unlock(out);
192 		return ERR_PTR(-EIDRM);
193 	}
194 
195 	return out;
196 }
197 
198 /**
199  * ipcget - Common sys_*get() code
200  * @ns : namsepace
201  * @ids : IPC identifier set
202  * @ops : operations to be called on ipc object creation, permission checks
203  *        and further checks
204  * @params : the parameters needed by the previous operations.
205  *
206  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
207  */
208 static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
209 			struct ipc_ops *ops, struct ipc_params *params)
210 {
211 	if (params->key == IPC_PRIVATE)
212 		return ipcget_new(ns, ids, ops, params);
213 	else
214 		return ipcget_public(ns, ids, ops, params);
215 }
216 
217 #endif
218