1 /**
2 * eCryptfs: Linux filesystem encryption layer
3 *
4 * Copyright (C) 2008 International Business Machines Corp.
5 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License version
9 * 2 as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
19 * 02111-1307, USA.
20 */
21
22 #include <linux/fs.h>
23 #include <linux/hash.h>
24 #include <linux/random.h>
25 #include <linux/miscdevice.h>
26 #include <linux/poll.h>
27 #include <linux/slab.h>
28 #include <linux/wait.h>
29 #include <linux/module.h>
30 #include "ecryptfs_kernel.h"
31
32 static atomic_t ecryptfs_num_miscdev_opens;
33
34 /**
35 * ecryptfs_miscdev_poll
36 * @file: dev file (ignored)
37 * @pt: dev poll table (ignored)
38 *
39 * Returns the poll mask
40 */
41 static unsigned int
ecryptfs_miscdev_poll(struct file * file,poll_table * pt)42 ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
43 {
44 struct ecryptfs_daemon *daemon;
45 unsigned int mask = 0;
46 uid_t euid = current_euid();
47 int rc;
48
49 mutex_lock(&ecryptfs_daemon_hash_mux);
50 /* TODO: Just use file->private_data? */
51 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
52 if (rc || !daemon) {
53 mutex_unlock(&ecryptfs_daemon_hash_mux);
54 return -EINVAL;
55 }
56 mutex_lock(&daemon->mux);
57 mutex_unlock(&ecryptfs_daemon_hash_mux);
58 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
59 printk(KERN_WARNING "%s: Attempt to poll on zombified "
60 "daemon\n", __func__);
61 goto out_unlock_daemon;
62 }
63 if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
64 goto out_unlock_daemon;
65 if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
66 goto out_unlock_daemon;
67 daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
68 mutex_unlock(&daemon->mux);
69 poll_wait(file, &daemon->wait, pt);
70 mutex_lock(&daemon->mux);
71 if (!list_empty(&daemon->msg_ctx_out_queue))
72 mask |= POLLIN | POLLRDNORM;
73 out_unlock_daemon:
74 daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
75 mutex_unlock(&daemon->mux);
76 return mask;
77 }
78
79 /**
80 * ecryptfs_miscdev_open
81 * @inode: inode of miscdev handle (ignored)
82 * @file: file for miscdev handle (ignored)
83 *
84 * Returns zero on success; non-zero otherwise
85 */
86 static int
ecryptfs_miscdev_open(struct inode * inode,struct file * file)87 ecryptfs_miscdev_open(struct inode *inode, struct file *file)
88 {
89 struct ecryptfs_daemon *daemon = NULL;
90 uid_t euid = current_euid();
91 int rc;
92
93 mutex_lock(&ecryptfs_daemon_hash_mux);
94 rc = try_module_get(THIS_MODULE);
95 if (rc == 0) {
96 rc = -EIO;
97 printk(KERN_ERR "%s: Error attempting to increment module use "
98 "count; rc = [%d]\n", __func__, rc);
99 goto out_unlock_daemon_list;
100 }
101 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
102 if (rc || !daemon) {
103 rc = ecryptfs_spawn_daemon(&daemon, euid, current_user_ns(),
104 task_pid(current));
105 if (rc) {
106 printk(KERN_ERR "%s: Error attempting to spawn daemon; "
107 "rc = [%d]\n", __func__, rc);
108 goto out_module_put_unlock_daemon_list;
109 }
110 }
111 mutex_lock(&daemon->mux);
112 if (daemon->pid != task_pid(current)) {
113 rc = -EINVAL;
114 printk(KERN_ERR "%s: pid [0x%p] has registered with euid [%d], "
115 "but pid [0x%p] has attempted to open the handle "
116 "instead\n", __func__, daemon->pid, daemon->euid,
117 task_pid(current));
118 goto out_unlock_daemon;
119 }
120 if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
121 rc = -EBUSY;
122 printk(KERN_ERR "%s: Miscellaneous device handle may only be "
123 "opened once per daemon; pid [0x%p] already has this "
124 "handle open\n", __func__, daemon->pid);
125 goto out_unlock_daemon;
126 }
127 daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN;
128 file->private_data = daemon;
129 atomic_inc(&ecryptfs_num_miscdev_opens);
130 out_unlock_daemon:
131 mutex_unlock(&daemon->mux);
132 out_module_put_unlock_daemon_list:
133 if (rc)
134 module_put(THIS_MODULE);
135 out_unlock_daemon_list:
136 mutex_unlock(&ecryptfs_daemon_hash_mux);
137 return rc;
138 }
139
140 /**
141 * ecryptfs_miscdev_release
142 * @inode: inode of fs/ecryptfs/euid handle (ignored)
143 * @file: file for fs/ecryptfs/euid handle (ignored)
144 *
145 * This keeps the daemon registered until the daemon sends another
146 * ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
147 *
148 * Returns zero on success; non-zero otherwise
149 */
150 static int
ecryptfs_miscdev_release(struct inode * inode,struct file * file)151 ecryptfs_miscdev_release(struct inode *inode, struct file *file)
152 {
153 struct ecryptfs_daemon *daemon = NULL;
154 uid_t euid = current_euid();
155 int rc;
156
157 mutex_lock(&ecryptfs_daemon_hash_mux);
158 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
159 if (rc || !daemon)
160 daemon = file->private_data;
161 mutex_lock(&daemon->mux);
162 BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
163 daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
164 atomic_dec(&ecryptfs_num_miscdev_opens);
165 mutex_unlock(&daemon->mux);
166 rc = ecryptfs_exorcise_daemon(daemon);
167 if (rc) {
168 printk(KERN_CRIT "%s: Fatal error whilst attempting to "
169 "shut down daemon; rc = [%d]. Please report this "
170 "bug.\n", __func__, rc);
171 BUG();
172 }
173 module_put(THIS_MODULE);
174 mutex_unlock(&ecryptfs_daemon_hash_mux);
175 return rc;
176 }
177
178 /**
179 * ecryptfs_send_miscdev
180 * @data: Data to send to daemon; may be NULL
181 * @data_size: Amount of data to send to daemon
182 * @msg_ctx: Message context, which is used to handle the reply. If
183 * this is NULL, then we do not expect a reply.
184 * @msg_type: Type of message
185 * @msg_flags: Flags for message
186 * @daemon: eCryptfs daemon object
187 *
188 * Add msg_ctx to queue and then, if it exists, notify the blocked
189 * miscdevess about the data being available. Must be called with
190 * ecryptfs_daemon_hash_mux held.
191 *
192 * Returns zero on success; non-zero otherwise
193 */
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)194 int ecryptfs_send_miscdev(char *data, size_t data_size,
195 struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
196 u16 msg_flags, struct ecryptfs_daemon *daemon)
197 {
198 struct ecryptfs_message *msg;
199
200 msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
201 if (!msg) {
202 printk(KERN_ERR "%s: Out of memory whilst attempting "
203 "to kmalloc(%zd, GFP_KERNEL)\n", __func__,
204 (sizeof(*msg) + data_size));
205 return -ENOMEM;
206 }
207
208 mutex_lock(&msg_ctx->mux);
209 msg_ctx->msg = msg;
210 msg_ctx->msg->index = msg_ctx->index;
211 msg_ctx->msg->data_len = data_size;
212 msg_ctx->type = msg_type;
213 memcpy(msg_ctx->msg->data, data, data_size);
214 msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
215 list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
216 mutex_unlock(&msg_ctx->mux);
217
218 mutex_lock(&daemon->mux);
219 daemon->num_queued_msg_ctx++;
220 wake_up_interruptible(&daemon->wait);
221 mutex_unlock(&daemon->mux);
222
223 return 0;
224 }
225
226 /*
227 * miscdevfs packet format:
228 * Octet 0: Type
229 * Octets 1-4: network byte order msg_ctx->counter
230 * Octets 5-N0: Size of struct ecryptfs_message to follow
231 * Octets N0-N1: struct ecryptfs_message (including data)
232 *
233 * Octets 5-N1 not written if the packet type does not include a message
234 */
235 #define PKT_TYPE_SIZE 1
236 #define PKT_CTR_SIZE 4
237 #define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
238 #define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
239 + ECRYPTFS_MIN_PKT_LEN_SIZE)
240 /* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
241 #define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
242 + ECRYPTFS_MAX_PKT_LEN_SIZE \
243 + sizeof(struct ecryptfs_message) \
244 + 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
245 #define PKT_TYPE_OFFSET 0
246 #define PKT_CTR_OFFSET PKT_TYPE_SIZE
247 #define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
248
249 /**
250 * ecryptfs_miscdev_read - format and send message from queue
251 * @file: fs/ecryptfs/euid miscdevfs handle (ignored)
252 * @buf: User buffer into which to copy the next message on the daemon queue
253 * @count: Amount of space available in @buf
254 * @ppos: Offset in file (ignored)
255 *
256 * Pulls the most recent message from the daemon queue, formats it for
257 * being sent via a miscdevfs handle, and copies it into @buf
258 *
259 * Returns the number of bytes copied into the user buffer
260 */
261 static ssize_t
ecryptfs_miscdev_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)262 ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
263 loff_t *ppos)
264 {
265 struct ecryptfs_daemon *daemon;
266 struct ecryptfs_msg_ctx *msg_ctx;
267 size_t packet_length_size;
268 char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
269 size_t i;
270 size_t total_length;
271 uid_t euid = current_euid();
272 int rc;
273
274 mutex_lock(&ecryptfs_daemon_hash_mux);
275 /* TODO: Just use file->private_data? */
276 rc = ecryptfs_find_daemon_by_euid(&daemon, euid, current_user_ns());
277 if (rc || !daemon) {
278 mutex_unlock(&ecryptfs_daemon_hash_mux);
279 return -EINVAL;
280 }
281 mutex_lock(&daemon->mux);
282 if (task_pid(current) != daemon->pid) {
283 mutex_unlock(&daemon->mux);
284 mutex_unlock(&ecryptfs_daemon_hash_mux);
285 return -EPERM;
286 }
287 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
288 rc = 0;
289 mutex_unlock(&ecryptfs_daemon_hash_mux);
290 printk(KERN_WARNING "%s: Attempt to read from zombified "
291 "daemon\n", __func__);
292 goto out_unlock_daemon;
293 }
294 if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
295 rc = 0;
296 mutex_unlock(&ecryptfs_daemon_hash_mux);
297 goto out_unlock_daemon;
298 }
299 /* This daemon will not go away so long as this flag is set */
300 daemon->flags |= ECRYPTFS_DAEMON_IN_READ;
301 mutex_unlock(&ecryptfs_daemon_hash_mux);
302 check_list:
303 if (list_empty(&daemon->msg_ctx_out_queue)) {
304 mutex_unlock(&daemon->mux);
305 rc = wait_event_interruptible(
306 daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
307 mutex_lock(&daemon->mux);
308 if (rc < 0) {
309 rc = 0;
310 goto out_unlock_daemon;
311 }
312 }
313 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
314 rc = 0;
315 goto out_unlock_daemon;
316 }
317 if (list_empty(&daemon->msg_ctx_out_queue)) {
318 /* Something else jumped in since the
319 * wait_event_interruptable() and removed the
320 * message from the queue; try again */
321 goto check_list;
322 }
323 msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
324 struct ecryptfs_msg_ctx, daemon_out_list);
325 BUG_ON(!msg_ctx);
326 mutex_lock(&msg_ctx->mux);
327 if (msg_ctx->msg) {
328 rc = ecryptfs_write_packet_length(packet_length,
329 msg_ctx->msg_size,
330 &packet_length_size);
331 if (rc) {
332 rc = 0;
333 printk(KERN_WARNING "%s: Error writing packet length; "
334 "rc = [%d]\n", __func__, rc);
335 goto out_unlock_msg_ctx;
336 }
337 } else {
338 packet_length_size = 0;
339 msg_ctx->msg_size = 0;
340 }
341 total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
342 + msg_ctx->msg_size);
343 if (count < total_length) {
344 rc = 0;
345 printk(KERN_WARNING "%s: Only given user buffer of "
346 "size [%zd], but we need [%zd] to read the "
347 "pending message\n", __func__, count, total_length);
348 goto out_unlock_msg_ctx;
349 }
350 rc = -EFAULT;
351 if (put_user(msg_ctx->type, buf))
352 goto out_unlock_msg_ctx;
353 if (put_user(cpu_to_be32(msg_ctx->counter),
354 (__be32 __user *)(&buf[PKT_CTR_OFFSET])))
355 goto out_unlock_msg_ctx;
356 i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
357 if (msg_ctx->msg) {
358 if (copy_to_user(&buf[i], packet_length, packet_length_size))
359 goto out_unlock_msg_ctx;
360 i += packet_length_size;
361 if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
362 goto out_unlock_msg_ctx;
363 i += msg_ctx->msg_size;
364 }
365 rc = i;
366 list_del(&msg_ctx->daemon_out_list);
367 kfree(msg_ctx->msg);
368 msg_ctx->msg = NULL;
369 /* We do not expect a reply from the userspace daemon for any
370 * message type other than ECRYPTFS_MSG_REQUEST */
371 if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
372 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
373 out_unlock_msg_ctx:
374 mutex_unlock(&msg_ctx->mux);
375 out_unlock_daemon:
376 daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
377 mutex_unlock(&daemon->mux);
378 return rc;
379 }
380
381 /**
382 * ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
383 * @data: Bytes comprising struct ecryptfs_message
384 * @data_size: sizeof(struct ecryptfs_message) + data len
385 * @euid: Effective user id of miscdevess sending the miscdev response
386 * @user_ns: The namespace in which @euid applies
387 * @pid: Miscdevess id of miscdevess sending the miscdev response
388 * @seq: Sequence number for miscdev response packet
389 *
390 * Returns zero on success; non-zero otherwise
391 */
ecryptfs_miscdev_response(char * data,size_t data_size,uid_t euid,struct user_namespace * user_ns,struct pid * pid,u32 seq)392 static int ecryptfs_miscdev_response(char *data, size_t data_size,
393 uid_t euid, struct user_namespace *user_ns,
394 struct pid *pid, u32 seq)
395 {
396 struct ecryptfs_message *msg = (struct ecryptfs_message *)data;
397 int rc;
398
399 if ((sizeof(*msg) + msg->data_len) != data_size) {
400 printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
401 "[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
402 (sizeof(*msg) + msg->data_len), data_size);
403 rc = -EINVAL;
404 goto out;
405 }
406 rc = ecryptfs_process_response(msg, euid, user_ns, pid, seq);
407 if (rc)
408 printk(KERN_ERR
409 "Error processing response message; rc = [%d]\n", rc);
410 out:
411 return rc;
412 }
413
414 /**
415 * ecryptfs_miscdev_write - handle write to daemon miscdev handle
416 * @file: File for misc dev handle (ignored)
417 * @buf: Buffer containing user data
418 * @count: Amount of data in @buf
419 * @ppos: Pointer to offset in file (ignored)
420 *
421 * Returns the number of bytes read from @buf
422 */
423 static ssize_t
ecryptfs_miscdev_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)424 ecryptfs_miscdev_write(struct file *file, const char __user *buf,
425 size_t count, loff_t *ppos)
426 {
427 __be32 counter_nbo;
428 u32 seq;
429 size_t packet_size, packet_size_length;
430 char *data;
431 uid_t euid = current_euid();
432 unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
433 ssize_t rc;
434
435 if (count == 0) {
436 return 0;
437 } else if (count == MIN_NON_MSG_PKT_SIZE) {
438 /* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
439 goto memdup;
440 } else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
441 printk(KERN_WARNING "%s: Acceptable packet size range is "
442 "[%d-%zu], but amount of data written is [%zu].",
443 __func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
444 return -EINVAL;
445 }
446
447 if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
448 sizeof(packet_size_peek))) {
449 printk(KERN_WARNING "%s: Error while inspecting packet size\n",
450 __func__);
451 return -EFAULT;
452 }
453
454 rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
455 &packet_size_length);
456 if (rc) {
457 printk(KERN_WARNING "%s: Error parsing packet length; "
458 "rc = [%zd]\n", __func__, rc);
459 return rc;
460 }
461
462 if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
463 != count) {
464 printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
465 packet_size);
466 return -EINVAL;
467 }
468
469 memdup:
470 data = memdup_user(buf, count);
471 if (IS_ERR(data)) {
472 printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
473 __func__, PTR_ERR(data));
474 return PTR_ERR(data);
475 }
476 switch (data[PKT_TYPE_OFFSET]) {
477 case ECRYPTFS_MSG_RESPONSE:
478 if (count < (MIN_MSG_PKT_SIZE
479 + sizeof(struct ecryptfs_message))) {
480 printk(KERN_WARNING "%s: Minimum acceptable packet "
481 "size is [%zd], but amount of data written is "
482 "only [%zd]. Discarding response packet.\n",
483 __func__,
484 (MIN_MSG_PKT_SIZE
485 + sizeof(struct ecryptfs_message)), count);
486 rc = -EINVAL;
487 goto out_free;
488 }
489 memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
490 seq = be32_to_cpu(counter_nbo);
491 rc = ecryptfs_miscdev_response(
492 &data[PKT_LEN_OFFSET + packet_size_length],
493 packet_size, euid, current_user_ns(),
494 task_pid(current), seq);
495 if (rc) {
496 printk(KERN_WARNING "%s: Failed to deliver miscdev "
497 "response to requesting operation; rc = [%zd]\n",
498 __func__, rc);
499 goto out_free;
500 }
501 break;
502 case ECRYPTFS_MSG_HELO:
503 case ECRYPTFS_MSG_QUIT:
504 break;
505 default:
506 ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
507 "message of unrecognized type [%d]\n",
508 data[0]);
509 rc = -EINVAL;
510 goto out_free;
511 }
512 rc = count;
513 out_free:
514 kfree(data);
515 return rc;
516 }
517
518
519 static const struct file_operations ecryptfs_miscdev_fops = {
520 .open = ecryptfs_miscdev_open,
521 .poll = ecryptfs_miscdev_poll,
522 .read = ecryptfs_miscdev_read,
523 .write = ecryptfs_miscdev_write,
524 .release = ecryptfs_miscdev_release,
525 .llseek = noop_llseek,
526 };
527
528 static struct miscdevice ecryptfs_miscdev = {
529 .minor = MISC_DYNAMIC_MINOR,
530 .name = "ecryptfs",
531 .fops = &ecryptfs_miscdev_fops
532 };
533
534 /**
535 * ecryptfs_init_ecryptfs_miscdev
536 *
537 * Messages sent to the userspace daemon from the kernel are placed on
538 * a queue associated with the daemon. The next read against the
539 * miscdev handle by that daemon will return the oldest message placed
540 * on the message queue for the daemon.
541 *
542 * Returns zero on success; non-zero otherwise
543 */
ecryptfs_init_ecryptfs_miscdev(void)544 int __init ecryptfs_init_ecryptfs_miscdev(void)
545 {
546 int rc;
547
548 atomic_set(&ecryptfs_num_miscdev_opens, 0);
549 rc = misc_register(&ecryptfs_miscdev);
550 if (rc)
551 printk(KERN_ERR "%s: Failed to register miscellaneous device "
552 "for communications with userspace daemons; rc = [%d]\n",
553 __func__, rc);
554 return rc;
555 }
556
557 /**
558 * ecryptfs_destroy_ecryptfs_miscdev
559 *
560 * All of the daemons must be exorcised prior to calling this
561 * function.
562 */
ecryptfs_destroy_ecryptfs_miscdev(void)563 void ecryptfs_destroy_ecryptfs_miscdev(void)
564 {
565 BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0);
566 misc_deregister(&ecryptfs_miscdev);
567 }
568