summaryrefslogtreecommitdiff
path: root/fs/ecryptfs/miscdev.c
blob: 3745f612bcd438cb477f8bb245afeb5f47495f89 (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
517
518
519
520
521
522
523
524
525
526
/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 2008 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
 *
 * 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/fs.h>
#include <linux/hash.h>
#include <linux/random.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/module.h>
#include "ecryptfs_kernel.h"

static atomic_t ecryptfs_num_miscdev_opens;

/**
 * ecryptfs_miscdev_poll
 * @file: dev file (ignored)
 * @pt: dev poll table (ignored)
 *
 * Returns the poll mask
 */
static unsigned int
ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
{
	struct ecryptfs_daemon *daemon;
	unsigned int mask = 0;
	uid_t euid = current_euid();
	int rc;

	mutex_lock(&ecryptfs_daemon_hash_mux);
	/* TODO: Just use file->private_data? */
	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
	BUG_ON(rc || !daemon);
	mutex_lock(&daemon->mux);
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
		printk(KERN_WARNING "%s: Attempt to poll on zombified "
		       "daemon\n", __func__);
		goto out_unlock_daemon;
	}
	if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
		goto out_unlock_daemon;
	if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
		goto out_unlock_daemon;
	daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
	mutex_unlock(&daemon->mux);
	poll_wait(file, &daemon->wait, pt);
	mutex_lock(&daemon->mux);
	if (!list_empty(&daemon->msg_ctx_out_queue))
		mask |= POLLIN | POLLRDNORM;
out_unlock_daemon:
	daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
	mutex_unlock(&daemon->mux);
	return mask;
}

/**
 * ecryptfs_miscdev_open
 * @inode: inode of miscdev handle (ignored)
 * @file: file for miscdev handle (ignored)
 *
 * Returns zero on success; non-zero otherwise
 */
static int
ecryptfs_miscdev_open(struct inode *inode, struct file *file)
{
	struct ecryptfs_daemon *daemon = NULL;
	uid_t euid = current_euid();
	int rc;

	mutex_lock(&ecryptfs_daemon_hash_mux);
	rc = try_module_get(THIS_MODULE);
	if (rc == 0) {
		rc = -EIO;
		printk(KERN_ERR "%s: Error attempting to increment module use "
		       "count; rc = [%d]\n", __func__, rc);
		goto out_unlock_daemon_list;
	}
	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
	if (rc || !daemon) {
		rc = ecryptfs_spawn_daemon(&daemon, euid, current_user_ns(),
					   task_pid(current));
		if (rc) {
			printk(KERN_ERR "%s: Error attempting to spawn daemon; "
			       "rc = [%d]\n", __func__, rc);
			goto out_module_put_unlock_daemon_list;
		}
	}
	mutex_lock(&daemon->mux);
	if (daemon->pid != task_pid(current)) {
		rc = -EINVAL;
		printk(KERN_ERR "%s: pid [0x%p] has registered with euid [%d], "
		       "but pid [0x%p] has attempted to open the handle "
		       "instead\n", __func__, daemon->pid, daemon->euid,
		       task_pid(current));
		goto out_unlock_daemon;
	}
	if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
		rc = -EBUSY;
		printk(KERN_ERR "%s: Miscellaneous device handle may only be "
		       "opened once per daemon; pid [0x%p] already has this "
		       "handle open\n", __func__, daemon->pid);
		goto out_unlock_daemon;
	}
	daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN;
	atomic_inc(&ecryptfs_num_miscdev_opens);
out_unlock_daemon:
	mutex_unlock(&daemon->mux);
out_module_put_unlock_daemon_list:
	if (rc)
		module_put(THIS_MODULE);
out_unlock_daemon_list:
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	return rc;
}

/**
 * ecryptfs_miscdev_release
 * @inode: inode of fs/ecryptfs/euid handle (ignored)
 * @file: file for fs/ecryptfs/euid handle (ignored)
 *
 * This keeps the daemon registered until the daemon sends another
 * ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
 *
 * Returns zero on success; non-zero otherwise
 */
static int
ecryptfs_miscdev_release(struct inode *inode, struct file *file)
{
	struct ecryptfs_daemon *daemon = NULL;
	uid_t euid = current_euid();
	int rc;

	mutex_lock(&ecryptfs_daemon_hash_mux);
	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
	BUG_ON(rc || !daemon);
	mutex_lock(&daemon->mux);
	BUG_ON(daemon->pid != task_pid(current));
	BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
	daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
	atomic_dec(&ecryptfs_num_miscdev_opens);
	mutex_unlock(&daemon->mux);
	rc = ecryptfs_exorcise_daemon(daemon);
	if (rc) {
		printk(KERN_CRIT "%s: Fatal error whilst attempting to "
		       "shut down daemon; rc = [%d]. Please report this "
		       "bug.\n", __func__, rc);
		BUG();
	}
	module_put(THIS_MODULE);
	mutex_unlock(&ecryptfs_daemon_hash_mux);
	return rc;
}

/**
 * ecryptfs_send_miscdev
 * @data: Data to send to daemon; may be NULL
 * @data_size: Amount of data to send to daemon
 * @msg_ctx: Message context, which is used to handle the reply. If
 *           this is NULL, then we do not expect a reply.
 * @msg_type: Type of message
 * @msg_flags: Flags for message
 * @daemon: eCryptfs daemon object
 *
 * Add msg_ctx to queue and then, if it exists, notify the blocked
 * miscdevess about the data being available. Must be called with
 * ecryptfs_daemon_hash_mux held.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_send_miscdev(char *data, size_t data_size,
			  struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
			  u16 msg_flags, struct ecryptfs_daemon *daemon)
{
	int rc = 0;

	mutex_lock(&msg_ctx->mux);
	msg_ctx->msg = kmalloc((sizeof(*msg_ctx->msg) + data_size),
			       GFP_KERNEL);
	if (!msg_ctx->msg) {
		rc = -ENOMEM;
		printk(KERN_ERR "%s: Out of memory whilst attempting "
		       "to kmalloc(%zd, GFP_KERNEL)\n", __func__,
		       (sizeof(*msg_ctx->msg) + data_size));
		goto out_unlock;
	}
	msg_ctx->msg->index = msg_ctx->index;
	msg_ctx->msg->data_len = data_size;
	msg_ctx->type = msg_type;
	memcpy(msg_ctx->msg->data, data, data_size);
	msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
	mutex_lock(&daemon->mux);
	list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
	daemon->num_queued_msg_ctx++;
	wake_up_interruptible(&daemon->wait);
	mutex_unlock(&daemon->mux);
out_unlock:
	mutex_unlock(&msg_ctx->mux);
	return rc;
}

/**
 * ecryptfs_miscdev_read - format and send message from queue
 * @file: fs/ecryptfs/euid miscdevfs handle (ignored)
 * @buf: User buffer into which to copy the next message on the daemon queue
 * @count: Amount of space available in @buf
 * @ppos: Offset in file (ignored)
 *
 * Pulls the most recent message from the daemon queue, formats it for
 * being sent via a miscdevfs handle, and copies it into @buf
 *
 * Returns the number of bytes copied into the user buffer
 */
static ssize_t
ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
		      loff_t *ppos)
{
	struct ecryptfs_daemon *daemon;
	struct ecryptfs_msg_ctx *msg_ctx;
	size_t packet_length_size;
	char packet_length[3];
	size_t i;
	size_t total_length;
	uid_t euid = current_euid();
	int rc;

	mutex_lock(&ecryptfs_daemon_hash_mux);
	/* TODO: Just use file->private_data? */
	rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
	BUG_ON(rc || !daemon);
	mutex_lock(&daemon->mux);
	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
		rc = 0;
		mutex_unlock(&ecryptfs_daemon_hash_mux);
		printk(KERN_WARNING "%s: Attempt to read from zombified "
		       "daemon\n", __func__);
		goto out_unlock_daemon;
	}
	if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
		rc = 0;
		mutex_unlock(&ecryptfs_daemon_hash_mux);
		goto out_unlock_daemon;
	}
	/* This daemon will not go away so long as this flag is set */
	daemon->flags |= ECRYPTFS_DAEMON_IN_READ;
	mutex_unlock(&ecryptfs_daemon_hash_mux);
check_list:
	if (list_empty(&daemon->msg_ctx_out_queue)) {
		mutex_unlock(&daemon->mux);
		rc = wait_event_interruptible(
			daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
		mutex_lock(&daemon->mux);
		if (rc < 0) {
			rc = 0;
			goto out_unlock_daemon;
		}
	}
	if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
		rc = 0;
		goto out_unlock_daemon;
	}
	if (list_empty(&daemon->msg_ctx_out_queue)) {
		/* Something else jumped in since the
		 * wait_event_interruptable() and removed the
		 * message from the queue; try again */
		goto check_list;
	}
	BUG_ON(euid != daemon->euid);
	BUG_ON(current_user_ns() != daemon->user_ns);
	BUG_ON(task_pid(current) != daemon->pid);
	msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
				   struct ecryptfs_msg_ctx, daemon_out_list);
	BUG_ON(!msg_ctx);
	mutex_lock(&msg_ctx->mux);
	if (msg_ctx->msg) {
		rc = ecryptfs_write_packet_length(packet_length,
						  msg_ctx->msg_size,
						  &packet_length_size);
		if (rc) {
			rc = 0;
			printk(KERN_WARNING "%s: Error writing packet length; "
			       "rc = [%d]\n", __func__, rc);
			goto out_unlock_msg_ctx;
		}
	} else {
		packet_length_size = 0;
		msg_ctx->msg_size = 0;
	}
	/* miscdevfs packet format:
	 *  Octet 0: Type
	 *  Octets 1-4: network byte order msg_ctx->counter
	 *  Octets 5-N0: Size of struct ecryptfs_message to follow
	 *  Octets N0-N1: struct ecryptfs_message (including data)
	 *
	 *  Octets 5-N1 not written if the packet type does not
	 *  include a message */
	total_length = (1 + 4 + packet_length_size + msg_ctx->msg_size);
	if (count < total_length) {
		rc = 0;
		printk(KERN_WARNING "%s: Only given user buffer of "
		       "size [%zd], but we need [%zd] to read the "
		       "pending message\n", __func__, count, total_length);
		goto out_unlock_msg_ctx;
	}
	rc = -EFAULT;
	if (put_user(msg_ctx->type, buf))
		goto out_unlock_msg_ctx;
	if (put_user(cpu_to_be32(msg_ctx->counter), (__be32 __user *)(buf + 1)))
		goto out_unlock_msg_ctx;
	i = 5;
	if (msg_ctx->msg) {
		if (copy_to_user(&buf[i], packet_length, packet_length_size))
			goto out_unlock_msg_ctx;
		i += packet_length_size;
		if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
			goto out_unlock_msg_ctx;
		i += msg_ctx->msg_size;
	}
	rc = i;
	list_del(&msg_ctx->daemon_out_list);
	kfree(msg_ctx->msg);
	msg_ctx->msg = NULL;
	/* We do not expect a reply from the userspace daemon for any
	 * message type other than ECRYPTFS_MSG_REQUEST */
	if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
		ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
out_unlock_msg_ctx:
	mutex_unlock(&msg_ctx->mux);
out_unlock_daemon:
	daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
	mutex_unlock(&daemon->mux);
	return rc;
}

/**
 * ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
 * @data: Bytes comprising struct ecryptfs_message
 * @data_size: sizeof(struct ecryptfs_message) + data len
 * @euid: Effective user id of miscdevess sending the miscdev response
 * @user_ns: The namespace in which @euid applies
 * @pid: Miscdevess id of miscdevess sending the miscdev response
 * @seq: Sequence number for miscdev response packet
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_miscdev_response(char *data, size_t data_size,
				     uid_t euid, struct user_namespace *user_ns,
				     struct pid *pid, u32 seq)
{
	struct ecryptfs_message *msg = (struct ecryptfs_message *)data;
	int rc;

	if ((sizeof(*msg) + msg->data_len) != data_size) {
		printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
		       "[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
		       (sizeof(*msg) + msg->data_len), data_size);
		rc = -EINVAL;
		goto out;
	}
	rc = ecryptfs_process_response(msg, euid, user_ns, pid, seq);
	if (rc)
		printk(KERN_ERR
		       "Error processing response message; rc = [%d]\n", rc);
out:
	return rc;
}

/**
 * ecryptfs_miscdev_write - handle write to daemon miscdev handle
 * @file: File for misc dev handle (ignored)
 * @buf: Buffer containing user data
 * @count: Amount of data in @buf
 * @ppos: Pointer to offset in file (ignored)
 *
 * miscdevfs packet format:
 *  Octet 0: Type
 *  Octets 1-4: network byte order msg_ctx->counter (0's for non-response)
 *  Octets 5-N0: Size of struct ecryptfs_message to follow
 *  Octets N0-N1: struct ecryptfs_message (including data)
 *
 * Returns the number of bytes read from @buf
 */
static ssize_t
ecryptfs_miscdev_write(struct file *file, const char __user *buf,
		       size_t count, loff_t *ppos)
{
	__be32 counter_nbo;
	u32 seq;
	size_t packet_size, packet_size_length, i;
	ssize_t sz = 0;
	char *data;
	uid_t euid = current_euid();
	int rc;

	if (count == 0)
		goto out;

	data = memdup_user(buf, count);
	if (IS_ERR(data)) {
		printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
		       __func__, PTR_ERR(data));
		goto out;
	}
	sz = count;
	i = 0;
	switch (data[i++]) {
	case ECRYPTFS_MSG_RESPONSE:
		if (count < (1 + 4 + 1 + sizeof(struct ecryptfs_message))) {
			printk(KERN_WARNING "%s: Minimum acceptable packet "
			       "size is [%zd], but amount of data written is "
			       "only [%zd]. Discarding response packet.\n",
			       __func__,
			       (1 + 4 + 1 + sizeof(struct ecryptfs_message)),
			       count);
			goto out_free;
		}
		memcpy(&counter_nbo, &data[i], 4);
		seq = be32_to_cpu(counter_nbo);
		i += 4;
		rc = ecryptfs_parse_packet_length(&data[i], &packet_size,
						  &packet_size_length);
		if (rc) {
			printk(KERN_WARNING "%s: Error parsing packet length; "
			       "rc = [%d]\n", __func__, rc);
			goto out_free;
		}
		i += packet_size_length;
		if ((1 + 4 + packet_size_length + packet_size) != count) {
			printk(KERN_WARNING "%s: (1 + packet_size_length([%zd])"
			       " + packet_size([%zd]))([%zd]) != "
			       "count([%zd]). Invalid packet format.\n",
			       __func__, packet_size_length, packet_size,
			       (1 + packet_size_length + packet_size), count);
			goto out_free;
		}
		rc = ecryptfs_miscdev_response(&data[i], packet_size,
					       euid, current_user_ns(),
					       task_pid(current), seq);
		if (rc)
			printk(KERN_WARNING "%s: Failed to deliver miscdev "
			       "response to requesting operation; rc = [%d]\n",
			       __func__, rc);
		break;
	case ECRYPTFS_MSG_HELO:
	case ECRYPTFS_MSG_QUIT:
		break;
	default:
		ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
				"message of unrecognized type [%d]\n",
				data[0]);
		break;
	}
out_free:
	kfree(data);
out:
	return sz;
}


static const struct file_operations ecryptfs_miscdev_fops = {
	.open    = ecryptfs_miscdev_open,
	.poll    = ecryptfs_miscdev_poll,
	.read    = ecryptfs_miscdev_read,
	.write   = ecryptfs_miscdev_write,
	.release = ecryptfs_miscdev_release,
};

static struct miscdevice ecryptfs_miscdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name  = "ecryptfs",
	.fops  = &ecryptfs_miscdev_fops
};

/**
 * ecryptfs_init_ecryptfs_miscdev
 *
 * Messages sent to the userspace daemon from the kernel are placed on
 * a queue associated with the daemon. The next read against the
 * miscdev handle by that daemon will return the oldest message placed
 * on the message queue for the daemon.
 *
 * Returns zero on success; non-zero otherwise
 */
int ecryptfs_init_ecryptfs_miscdev(void)
{
	int rc;

	atomic_set(&ecryptfs_num_miscdev_opens, 0);
	rc = misc_register(&ecryptfs_miscdev);
	if (rc)
		printk(KERN_ERR "%s: Failed to register miscellaneous device "
		       "for communications with userspace daemons; rc = [%d]\n",
		       __func__, rc);
	return rc;
}

/**
 * ecryptfs_destroy_ecryptfs_miscdev
 *
 * All of the daemons must be exorcised prior to calling this
 * function.
 */
void ecryptfs_destroy_ecryptfs_miscdev(void)
{
	BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0);
	misc_deregister(&ecryptfs_miscdev);
}