summaryrefslogtreecommitdiffstats
path: root/ipc/util.c
blob: 85d7a65b2301505c586da2b96467f52302f80a3b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
/*
 * linux/ipc/util.c
 * Copyright (C) 1992 Krishna Balasubramanian
 *
 * Sep 1997 - Call suser() last after "normal" permission checks so we
 *            get BSD style process accounting right.
 *            Occurs in several places in the IPC code.
 *            Chris Evans, <chris@ferret.lmh.ox.ac.uk>
 * Nov 1999 - ipc helper functions, unified SMP locking
 *	      Manfred Spraul <manfreds@colorfullife.com>
 */

#include <linux/config.h>
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/init.h>
#include <linux/msg.h>
#include <linux/smp_lock.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/highuid.h>

#if defined(CONFIG_SYSVIPC)

#include "util.h"

/**
 *	ipc_init	-	initialise IPC subsystem
 *
 *	The various system5 IPC resources (semaphores, messages and shared
 *	memory are initialised
 */
 
void __init ipc_init (void)
{
	sem_init();
	msg_init();
	shm_init();
	return;
}

/**
 *	ipc_init_ids		-	initialise IPC identifiers
 *	@ids: Identifier set
 *	@size: Number of identifiers
 *
 *	Given a size for the ipc identifier range (limited below IPCMNI)
 *	set up the sequence range to use then allocate and initialise the
 *	array itself. 
 */
 
void __init ipc_init_ids(struct ipc_ids* ids, int size)
{
	int i;
	sema_init(&ids->sem,1);

	if(size > IPCMNI)
		size = IPCMNI;
	ids->size = size;
	ids->in_use = 0;
	ids->max_id = -1;
	ids->seq = 0;
	{
		int seq_limit = INT_MAX/SEQ_MULTIPLIER;
		if(seq_limit > USHRT_MAX)
			ids->seq_max = USHRT_MAX;
		 else
		 	ids->seq_max = seq_limit;
	}

	ids->entries = ipc_alloc(sizeof(struct ipc_id)*size);

	if(ids->entries == NULL) {
		printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
		ids->size = 0;
	}
	ids->ary = SPIN_LOCK_UNLOCKED;
	for(i=0;i<size;i++)
		ids->entries[i].p = NULL;
}

/**
 *	ipc_findkey	-	find a key in an ipc identifier set	
 *	@ids: Identifier set
 *	@key: The key to find
 *
 *	Returns the identifier if found or -1 if not.
 */
 
int ipc_findkey(struct ipc_ids* ids, key_t key)
{
	int id;
	struct kern_ipc_perm* p;

	for (id = 0; id <= ids->max_id; id++) {
		p = ids->entries[id].p;
		if(p==NULL)
			continue;
		if (key == p->key)
			return id;
	}
	return -1;
}

static int grow_ary(struct ipc_ids* ids, int newsize)
{
	struct ipc_id* new;
	struct ipc_id* old;
	int i;

	if(newsize > IPCMNI)
		newsize = IPCMNI;
	if(newsize <= ids->size)
		return newsize;

	new = ipc_alloc(sizeof(struct ipc_id)*newsize);
	if(new == NULL)
		return ids->size;
	memcpy(new, ids->entries, sizeof(struct ipc_id)*ids->size);
	for(i=ids->size;i<newsize;i++) {
		new[i].p = NULL;
	}
	spin_lock(&ids->ary);

	old = ids->entries;
	ids->entries = new;
	i = ids->size;
	ids->size = newsize;
	spin_unlock(&ids->ary);
	ipc_free(old, sizeof(struct ipc_id)*i);
	return ids->size;
}

/**
 *	ipc_addid 	-	add an IPC identifier
 *	@ids: IPC identifier set
 *	@new: new IPC permission set
 *	@size: new size limit for the id array
 *
 *	Add an entry 'new' to the IPC arrays. The permissions object is
 *	initialised and the first free entry is set up and the id assigned
 *	is returned. The list is returned in a locked state on success.
 *	On failure the list is not locked and -1 is returned.
 */
 
int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
{
	int id;

	size = grow_ary(ids,size);
	for (id = 0; id < size; id++) {
		if(ids->entries[id].p == NULL)
			goto found;
	}
	return -1;
found:
	ids->in_use++;
	if (id > ids->max_id)
		ids->max_id = id;

	new->cuid = new->uid = current->euid;
	new->gid = new->cgid = current->egid;

	new->seq = ids->seq++;
	if(ids->seq > ids->seq_max)
		ids->seq = 0;

	spin_lock(&ids->ary);
	ids->entries[id].p = new;
	return id;
}

/**
 *	ipc_rmid	-	remove an IPC identifier
 *	@ids: identifier set
 *	@id: Identifier to remove
 *
 *	The identifier must be valid, and in use. The kernel will panic if
 *	fed an invalid identifier. The entry is removed and internal
 *	variables recomputed. The object associated with the identifier
 *	is returned.
 */
 
struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
{
	struct kern_ipc_perm* p;
	int lid = id % SEQ_MULTIPLIER;
	if(lid >= ids->size)
		BUG();
	p = ids->entries[lid].p;
	ids->entries[lid].p = NULL;
	if(p==NULL)
		BUG();
	ids->in_use--;

	if (lid == ids->max_id) {
		do {
			lid--;
			if(lid == -1)
				break;
		} while (ids->entries[lid].p == NULL);
		ids->max_id = lid;
	}
	return p;
}

/**
 *	ipc_alloc	-	allocate ipc space
 *	@size: size desired
 *
 *	Allocate memory from the appropriate pools and return a pointer to it.
 *	NULL is returned if the allocation fails
 */
 
void* ipc_alloc(int size)
{
	void* out;
	if(size > PAGE_SIZE)
		out = vmalloc(size);
	else
		out = kmalloc(size, GFP_KERNEL);
	return out;
}

/**
 *	ipc_free	-	free ipc space
 *	@ptr: pointer returned by ipc_alloc
 *	@size: size of block
 *
 *	Free a block created with ipc_alloc. The caller must know the size
 *	used in the allocation call.
 */
 
void ipc_free(void* ptr, int size)
{
	if(size > PAGE_SIZE)
		vfree(ptr);
	else
		kfree(ptr);
}

/**
 *	ipcperms	-	check IPC permissions
 *	@ipcp: IPC permission set
 *	@flag: desired permission set.
 *
 *	Check user, group, other permissions for access
 *	to ipc resources. return 0 if allowed
 */
 
int ipcperms (struct kern_ipc_perm *ipcp, short flag)
{	/* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
	int requested_mode, granted_mode;

	requested_mode = (flag >> 6) | (flag >> 3) | flag;
	granted_mode = ipcp->mode;
	if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
		granted_mode >>= 6;
	else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
		granted_mode >>= 3;
	/* is there some bit set in requested_mode but not in granted_mode? */
	if ((requested_mode & ~granted_mode & 0007) && 
	    !capable(CAP_IPC_OWNER))
		return -1;

	return 0;
}

/*
 * Functions to convert between the kern_ipc_perm structure and the
 * old/new ipc_perm structures
 */

/**
 *	kernel_to_ipc64_perm	-	convert kernel ipc permissions to user
 *	@in: kernel permissions
 *	@out: new style IPC permissions
 *
 *	Turn the kernel object 'in' into a set of permissions descriptions
 *	for returning to userspace (out).
 */
 

void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
{
	out->key	= in->key;
	out->uid	= in->uid;
	out->gid	= in->gid;
	out->cuid	= in->cuid;
	out->cgid	= in->cgid;
	out->mode	= in->mode;
	out->seq	= in->seq;
}

/**
 *	ipc64_perm_to_ipc_perm	-	convert old ipc permissions to new
 *	@in: new style IPC permissions
 *	@out: old style IPC permissions
 *
 *	Turn the new style permissions object in into a compatibility
 *	object and store it into the 'out' pointer.
 */
 
void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
{
	out->key	= in->key;
	out->uid	= NEW_TO_OLD_UID(in->uid);
	out->gid	= NEW_TO_OLD_GID(in->gid);
	out->cuid	= NEW_TO_OLD_UID(in->cuid);
	out->cgid	= NEW_TO_OLD_GID(in->cgid);
	out->mode	= in->mode;
	out->seq	= in->seq;
}

#ifndef __ia64__

/**
 *	ipc_parse_version	-	IPC call version
 *	@cmd: pointer to command
 *
 *	Return IPC_64 for new style IPC and IPC_OLD for old style IPC. 
 *	The cmd value is turned from an encoding command and version into
 *	just the command code.
 */
 
int ipc_parse_version (int *cmd)
{
	if (*cmd & IPC_64) {
		*cmd ^= IPC_64;
		return IPC_64;
	} else {
		return IPC_OLD;
	}
}

#endif /* __ia64__ */

#else
/*
 * Dummy functions when SYSV IPC isn't configured
 */

void sem_exit (void)
{
    return;
}

asmlinkage long sys_semget (key_t key, int nsems, int semflg)
{
	return -ENOSYS;
}

asmlinkage long sys_semop (int semid, struct sembuf *sops, unsigned nsops)
{
	return -ENOSYS;
}

asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
{
	return -ENOSYS;
}

asmlinkage long sys_msgget (key_t key, int msgflg)
{
	return -ENOSYS;
}

asmlinkage long sys_msgsnd (int msqid, struct msgbuf *msgp, size_t msgsz, int msgflg)
{
	return -ENOSYS;
}

asmlinkage long sys_msgrcv (int msqid, struct msgbuf *msgp, size_t msgsz, long msgtyp,
		       int msgflg)
{
	return -ENOSYS;
}

asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds *buf)
{
	return -ENOSYS;
}

asmlinkage long sys_shmget (key_t key, size_t size, int shmflag)
{
	return -ENOSYS;
}

asmlinkage long sys_shmat (int shmid, char *shmaddr, int shmflg, ulong *addr)
{
	return -ENOSYS;
}

asmlinkage long sys_shmdt (char *shmaddr)
{
	return -ENOSYS;
}

asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds *buf)
{
	return -ENOSYS;
}

#endif /* CONFIG_SYSVIPC */