summaryrefslogtreecommitdiff
path: root/fs/ecryptfs/messaging.c
blob: a9d87c47f72dfda1c047d736f68512e7cff028ba (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
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2004-2006 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
 *		Tyler Hicks <tyhicks@ou.edu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */
#include <linux/sched.h>
#include "ecryptfs_kernel.h"

static LIST_HEAD(ecryptfs_msg_ctx_free_list);
static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
static struct mutex ecryptfs_msg_ctx_lists_mux;

static struct hlist_head *ecryptfs_daemon_id_hash;
static struct mutex ecryptfs_daemon_id_hash_mux;
static int ecryptfs_hash_buckets;
#define ecryptfs_uid_hash(uid) \
        hash_long((unsigned long)uid, ecryptfs_hash_buckets)

static unsigned int ecryptfs_msg_counter;
static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;

/**
 * ecryptfs_acquire_free_msg_ctx
 * @msg_ctx: The context that was acquired from the free list
 *
 * Acquires a context element from the free list and locks the mutex
 * on the context.  Returns zero on success; non-zero on error or upon
 * failure to acquire a free context element.  Be sure to lock the
 * list mutex before calling.
 */
static int ecryptfs_acquire_free_msg_ctx(struct ecryptfs_msg_ctx **msg_ctx)
{
	struct list_head *p;
	int rc;

	if (list_empty(&ecryptfs_msg_ctx_free_list)) {
		ecryptfs_printk(KERN_WARNING, "The eCryptfs free "
				"context list is empty.  It may be helpful to "
				"specify the ecryptfs_message_buf_len "
				"parameter to be greater than the current "
				"value of [%d]\n", ecryptfs_message_buf_len);
		rc = -ENOMEM;
		goto out;
	}
	list_for_each(p, &ecryptfs_msg_ctx_free_list) {
		*msg_ctx = list_entry(p, struct ecryptfs_msg_ctx, node);
		if (mutex_trylock(&(*msg_ctx)->mux)) {
			(*msg_ctx)->task = current;
			rc = 0;
			goto out;
		}
	}
	rc = -ENOMEM;
out:
	return rc;
}

/**
 * ecryptfs_msg_ctx_free_to_alloc
 * @msg_ctx: The context to move from the free list to the alloc list
 *
 * Be sure to lock the list mutex and the context mutex before
 * calling.
 */
static void ecryptfs_msg_ctx_free_to_alloc(struct ecryptfs_msg_ctx *msg_ctx)
{
	list_move(&msg_ctx->node, &ecryptfs_msg_ctx_alloc_list);
	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_PENDING;
	msg_ctx->counter = ++ecryptfs_msg_counter;
}

/**
 * ecryptfs_msg_ctx_alloc_to_free
 * @msg_ctx: The context to move from the alloc list to the free list
 *
 * Be sure to lock the list mutex and the context mutex before
 * calling.
 */
static void ecryptfs_msg_ctx_alloc_to_free(struct ecryptfs_msg_ctx *msg_ctx)
{
	list_move(&(msg_ctx->node), &ecryptfs_msg_ctx_free_list);
	if (msg_ctx->msg)
		kfree(msg_ctx->msg);
	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_FREE;
}

/**
 * ecryptfs_find_daemon_id
 * @uid: The user id which maps to the desired daemon id
 * @id: If return value is zero, points to the desired daemon id
 *      pointer
 *
 * Search the hash list for the given user id.  Returns zero if the
 * user id exists in the list; non-zero otherwise.  The daemon id hash
 * mutex should be held before calling this function.
 */
static int ecryptfs_find_daemon_id(uid_t uid, struct ecryptfs_daemon_id **id)
{
	struct hlist_node *elem;
	int rc;

	hlist_for_each_entry(*id, elem,
			     &ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)],
			     id_chain) {
		if ((*id)->uid == uid) {
			rc = 0;
			goto out;
		}
	}
	rc = -EINVAL;
out:
	return rc;
}

static int ecryptfs_send_raw_message(unsigned int transport, u16 msg_type,
				     pid_t pid)
{
	int rc;

	switch(transport) {
	case ECRYPTFS_TRANSPORT_NETLINK:
		rc = ecryptfs_send_netlink(NULL, 0, NULL, msg_type, 0, pid);
		break;
	case ECRYPTFS_TRANSPORT_CONNECTOR:
	case ECRYPTFS_TRANSPORT_RELAYFS:
	default:
		rc = -ENOSYS;
	}
	return rc;
}

/**
 * ecryptfs_process_helo
 * @transport: The underlying transport (netlink, etc.)
 * @uid: The user ID owner of the message
 * @pid: The process ID for the userspace program that sent the
 *       message
 *
 * Adds the uid and pid values to the daemon id hash.  If a uid
 * already has a daemon pid registered, the daemon will be
 * unregistered before the new daemon id is put into the hash list.
 * Returns zero after adding a new daemon id to the hash list;
 * non-zero otherwise.
 */
int ecryptfs_process_helo(unsigned int transport, uid_t uid, pid_t pid)
{
	struct ecryptfs_daemon_id *new_id;
	struct ecryptfs_daemon_id *old_id;
	int rc;

	mutex_lock(&ecryptfs_daemon_id_hash_mux);
	new_id = kmalloc(sizeof(*new_id), GFP_KERNEL);
	if (!new_id) {
		rc = -ENOMEM;
		ecryptfs_printk(KERN_ERR, "Failed to allocate memory; unable "
				"to register daemon [%d] for user [%d]\n",
				pid, uid);
		goto unlock;
	}
	if (!ecryptfs_find_daemon_id(uid, &old_id)) {
		printk(KERN_WARNING "Received request from user [%d] "
		       "to register daemon [%d]; unregistering daemon "
		       "[%d]\n", uid, pid, old_id->pid);
		hlist_del(&old_id->id_chain);
		rc = ecryptfs_send_raw_message(transport, ECRYPTFS_NLMSG_QUIT,
					       old_id->pid);
		if (rc)
			printk(KERN_WARNING "Failed to send QUIT "
			       "message to daemon [%d]; rc = [%d]\n",
			       old_id->pid, rc);
		kfree(old_id);
	}
	new_id->uid = uid;
	new_id->pid = pid;
	hlist_add_head(&new_id->id_chain,
		       &ecryptfs_daemon_id_hash[ecryptfs_uid_hash(uid)]);
	rc = 0;
unlock:
	mutex_unlock(&ecryptfs_daemon_id_hash_mux);
	return rc;
}

/**
 * ecryptfs_process_quit
 * @uid: The user ID owner of the message
 * @pid: The process ID for the userspace program that sent the
 *       message
 *
 * Deletes the corresponding daemon id for the given uid and pid, if
 * it is the registered that is requesting the deletion. Returns zero
 * after deleting the desired daemon id; non-zero otherwise.
 */
int ecryptfs_process_quit(uid_t uid, pid_t pid)
{
	struct ecryptfs_daemon_id *id;
	int rc;

	mutex_lock(&ecryptfs_daemon_id_hash_mux);
	if (ecryptfs_find_daemon_id(uid, &id)) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_ERR, "Received request from user [%d] to "
				"unregister unrecognized daemon [%d]\n", uid,
				pid);
		goto unlock;
	}
	if (id->pid != pid) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_WARNING, "Received request from user [%d] "
				"with pid [%d] to unregister daemon [%d]\n",
				uid, pid, id->pid);
		goto unlock;
	}
	hlist_del(&id->id_chain);
	kfree(id);
	rc = 0;
unlock:
	mutex_unlock(&ecryptfs_daemon_id_hash_mux);
	return rc;
}

/**
 * ecryptfs_process_reponse
 * @msg: The ecryptfs message received; the caller should sanity check
 *       msg->data_len
 * @pid: The process ID of the userspace application that sent the
 *       message
 * @seq: The sequence number of the message
 *
 * Processes a response message after sending a operation request to
 * userspace. Returns zero upon delivery to desired context element;
 * non-zero upon delivery failure or error.
 */
int ecryptfs_process_response(struct ecryptfs_message *msg, uid_t uid,
			      pid_t pid, u32 seq)
{
	struct ecryptfs_daemon_id *id;
	struct ecryptfs_msg_ctx *msg_ctx;
	int msg_size;
	int rc;

	if (msg->index >= ecryptfs_message_buf_len) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_ERR, "Attempt to reference "
				"context buffer at index [%d]; maximum "
				"allowable is [%d]\n", msg->index,
				(ecryptfs_message_buf_len - 1));
		goto out;
	}
	msg_ctx = &ecryptfs_msg_ctx_arr[msg->index];
	mutex_lock(&msg_ctx->mux);
	if (ecryptfs_find_daemon_id(msg_ctx->task->euid, &id)) {
		rc = -EBADMSG;
		ecryptfs_printk(KERN_WARNING, "User [%d] received a "
				"message response from process [%d] but does "
				"not have a registered daemon\n",
				msg_ctx->task->euid, pid);
		goto wake_up;
	}
	if (msg_ctx->task->euid != uid) {
		rc = -EBADMSG;
		ecryptfs_printk(KERN_WARNING, "Received message from user "
				"[%d]; expected message from user [%d]\n",
				uid, msg_ctx->task->euid);
		goto unlock;
	}
	if (id->pid != pid) {
		rc = -EBADMSG;
		ecryptfs_printk(KERN_ERR, "User [%d] received a "
				"message response from an unrecognized "
				"process [%d]\n", msg_ctx->task->euid, pid);
		goto unlock;
	}
	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_PENDING) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_WARNING, "Desired context element is not "
				"pending a response\n");
		goto unlock;
	} else if (msg_ctx->counter != seq) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_WARNING, "Invalid message sequence; "
				"expected [%d]; received [%d]\n",
				msg_ctx->counter, seq);
		goto unlock;
	}
	msg_size = sizeof(*msg) + msg->data_len;
	msg_ctx->msg = kmalloc(msg_size, GFP_KERNEL);
	if (!msg_ctx->msg) {
		rc = -ENOMEM;
		ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
		goto unlock;
	}
	memcpy(msg_ctx->msg, msg, msg_size);
	msg_ctx->state = ECRYPTFS_MSG_CTX_STATE_DONE;
	rc = 0;
wake_up:
	wake_up_process(msg_ctx->task);
unlock:
	mutex_unlock(&msg_ctx->mux);
out:
	return rc;
}

/**
 * ecryptfs_send_message
 * @transport: The transport over which to send the message (i.e.,
 *             netlink)
 * @data: The data to send
 * @data_len: The length of data
 * @msg_ctx: The message context allocated for the send
 */
int ecryptfs_send_message(unsigned int transport, char *data, int data_len,
			  struct ecryptfs_msg_ctx **msg_ctx)
{
	struct ecryptfs_daemon_id *id;
	int rc;

	mutex_lock(&ecryptfs_daemon_id_hash_mux);
	if (ecryptfs_find_daemon_id(current->euid, &id)) {
		mutex_unlock(&ecryptfs_daemon_id_hash_mux);
		rc = -ENOTCONN;
		ecryptfs_printk(KERN_ERR, "User [%d] does not have a daemon "
				"registered\n", current->euid);
		goto out;
	}
	mutex_unlock(&ecryptfs_daemon_id_hash_mux);
	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	rc = ecryptfs_acquire_free_msg_ctx(msg_ctx);
	if (rc) {
		mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
		ecryptfs_printk(KERN_WARNING, "Could not claim a free "
				"context element\n");
		goto out;
	}
	ecryptfs_msg_ctx_free_to_alloc(*msg_ctx);
	mutex_unlock(&(*msg_ctx)->mux);
	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	switch (transport) {
	case ECRYPTFS_TRANSPORT_NETLINK:
		rc = ecryptfs_send_netlink(data, data_len, *msg_ctx,
					   ECRYPTFS_NLMSG_REQUEST, 0, id->pid);
		break;
	case ECRYPTFS_TRANSPORT_CONNECTOR:
	case ECRYPTFS_TRANSPORT_RELAYFS:
	default:
		rc = -ENOSYS;
	}
	if (rc) {
		printk(KERN_ERR "Error attempting to send message to userspace "
		       "daemon; rc = [%d]\n", rc);
	}
out:
	return rc;
}

/**
 * ecryptfs_wait_for_response
 * @msg_ctx: The context that was assigned when sending a message
 * @msg: The incoming message from userspace; not set if rc != 0
 *
 * Sleeps until awaken by ecryptfs_receive_message or until the amount
 * of time exceeds ecryptfs_message_wait_timeout.  If zero is
 * returned, msg will point to a valid message from userspace; a
 * non-zero value is returned upon failure to receive a message or an
 * error occurs.
 */
int ecryptfs_wait_for_response(struct ecryptfs_msg_ctx *msg_ctx,
			       struct ecryptfs_message **msg)
{
	signed long timeout = ecryptfs_message_wait_timeout * HZ;
	int rc = 0;

sleep:
	timeout = schedule_timeout_interruptible(timeout);
	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	mutex_lock(&msg_ctx->mux);
	if (msg_ctx->state != ECRYPTFS_MSG_CTX_STATE_DONE) {
		if (timeout) {
			mutex_unlock(&msg_ctx->mux);
			mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
			goto sleep;
		}
		rc = -ENOMSG;
	} else {
		*msg = msg_ctx->msg;
		msg_ctx->msg = NULL;
	}
	ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
	mutex_unlock(&msg_ctx->mux);
	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	return rc;
}

int ecryptfs_init_messaging(unsigned int transport)
{
	int i;
	int rc = 0;

	if (ecryptfs_number_of_users > ECRYPTFS_MAX_NUM_USERS) {
		ecryptfs_number_of_users = ECRYPTFS_MAX_NUM_USERS;
		ecryptfs_printk(KERN_WARNING, "Specified number of users is "
				"too large, defaulting to [%d] users\n",
				ecryptfs_number_of_users);
	}
	mutex_init(&ecryptfs_daemon_id_hash_mux);
	mutex_lock(&ecryptfs_daemon_id_hash_mux);
	ecryptfs_hash_buckets = 0;
	while (ecryptfs_number_of_users >> ++ecryptfs_hash_buckets);
	ecryptfs_daemon_id_hash = kmalloc(sizeof(struct hlist_head)
					  * ecryptfs_hash_buckets, GFP_KERNEL);
	if (!ecryptfs_daemon_id_hash) {
		rc = -ENOMEM;
		ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
		goto out;
	}
	for (i = 0; i < ecryptfs_hash_buckets; i++)
		INIT_HLIST_HEAD(&ecryptfs_daemon_id_hash[i]);
	mutex_unlock(&ecryptfs_daemon_id_hash_mux);

	ecryptfs_msg_ctx_arr = kmalloc((sizeof(struct ecryptfs_msg_ctx)
				      * ecryptfs_message_buf_len), GFP_KERNEL);
	if (!ecryptfs_msg_ctx_arr) {
		rc = -ENOMEM;
		ecryptfs_printk(KERN_ERR, "Failed to allocate memory\n");
		goto out;
	}
	mutex_init(&ecryptfs_msg_ctx_lists_mux);
	mutex_lock(&ecryptfs_msg_ctx_lists_mux);
	ecryptfs_msg_counter = 0;
	for (i = 0; i < ecryptfs_message_buf_len; i++) {
		INIT_LIST_HEAD(&ecryptfs_msg_ctx_arr[i].node);
		mutex_init(&ecryptfs_msg_ctx_arr[i].mux);
		mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
		ecryptfs_msg_ctx_arr[i].index = i;
		ecryptfs_msg_ctx_arr[i].state = ECRYPTFS_MSG_CTX_STATE_FREE;
		ecryptfs_msg_ctx_arr[i].counter = 0;
		ecryptfs_msg_ctx_arr[i].task = NULL;
		ecryptfs_msg_ctx_arr[i].msg = NULL;
		list_add_tail(&ecryptfs_msg_ctx_arr[i].node,
			      &ecryptfs_msg_ctx_free_list);
		mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
	}
	mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	switch(transport) {
	case ECRYPTFS_TRANSPORT_NETLINK:
		rc = ecryptfs_init_netlink();
		if (rc)
			ecryptfs_release_messaging(transport);
		break;
	case ECRYPTFS_TRANSPORT_CONNECTOR:
	case ECRYPTFS_TRANSPORT_RELAYFS:
	default:
		rc = -ENOSYS;
	}
out:
	return rc;
}

void ecryptfs_release_messaging(unsigned int transport)
{
	if (ecryptfs_msg_ctx_arr) {
		int i;

		mutex_lock(&ecryptfs_msg_ctx_lists_mux);
		for (i = 0; i < ecryptfs_message_buf_len; i++) {
			mutex_lock(&ecryptfs_msg_ctx_arr[i].mux);
			if (ecryptfs_msg_ctx_arr[i].msg)
				kfree(ecryptfs_msg_ctx_arr[i].msg);
			mutex_unlock(&ecryptfs_msg_ctx_arr[i].mux);
		}
		kfree(ecryptfs_msg_ctx_arr);
		mutex_unlock(&ecryptfs_msg_ctx_lists_mux);
	}
	if (ecryptfs_daemon_id_hash) {
		struct hlist_node *elem;
		struct ecryptfs_daemon_id *id;
		int i;

		mutex_lock(&ecryptfs_daemon_id_hash_mux);
		for (i = 0; i < ecryptfs_hash_buckets; i++) {
			hlist_for_each_entry(id, elem,
					     &ecryptfs_daemon_id_hash[i],
					     id_chain) {
				hlist_del(elem);
				kfree(id);
			}
		}
		kfree(ecryptfs_daemon_id_hash);
		mutex_unlock(&ecryptfs_daemon_id_hash_mux);
	}
	switch(transport) {
	case ECRYPTFS_TRANSPORT_NETLINK:
		ecryptfs_release_netlink();
		break;
	case ECRYPTFS_TRANSPORT_CONNECTOR:
	case ECRYPTFS_TRANSPORT_RELAYFS:
	default:
		break;
	}
	return;
}