1 // SPDX-License-Identifier: GPL-2.0-only
2 /**
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 2008 International Business Machines Corp.
6 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
7 */
8
9 #include <linux/fs.h>
10 #include <linux/hash.h>
11 #include <linux/random.h>
12 #include <linux/miscdevice.h>
13 #include <linux/poll.h>
14 #include <linux/slab.h>
15 #include <linux/wait.h>
16 #include <linux/module.h>
17 #include "ecryptfs_kernel.h"
18
19 static atomic_t ecryptfs_num_miscdev_opens;
20
21 /**
22 * ecryptfs_miscdev_poll
23 * @file: dev file
24 * @pt: dev poll table (ignored)
25 *
26 * Returns the poll mask
27 */
28 static __poll_t
ecryptfs_miscdev_poll(struct file * file,poll_table * pt)29 ecryptfs_miscdev_poll(struct file *file, poll_table *pt)
30 {
31 struct ecryptfs_daemon *daemon = file->private_data;
32 __poll_t mask = 0;
33
34 mutex_lock(&daemon->mux);
35 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
36 printk(KERN_WARNING "%s: Attempt to poll on zombified "
37 "daemon\n", __func__);
38 goto out_unlock_daemon;
39 }
40 if (daemon->flags & ECRYPTFS_DAEMON_IN_READ)
41 goto out_unlock_daemon;
42 if (daemon->flags & ECRYPTFS_DAEMON_IN_POLL)
43 goto out_unlock_daemon;
44 daemon->flags |= ECRYPTFS_DAEMON_IN_POLL;
45 mutex_unlock(&daemon->mux);
46 poll_wait(file, &daemon->wait, pt);
47 mutex_lock(&daemon->mux);
48 if (!list_empty(&daemon->msg_ctx_out_queue))
49 mask |= EPOLLIN | EPOLLRDNORM;
50 out_unlock_daemon:
51 daemon->flags &= ~ECRYPTFS_DAEMON_IN_POLL;
52 mutex_unlock(&daemon->mux);
53 return mask;
54 }
55
56 /**
57 * ecryptfs_miscdev_open
58 * @inode: inode of miscdev handle (ignored)
59 * @file: file for miscdev handle
60 *
61 * Returns zero on success; non-zero otherwise
62 */
63 static int
ecryptfs_miscdev_open(struct inode * inode,struct file * file)64 ecryptfs_miscdev_open(struct inode *inode, struct file *file)
65 {
66 struct ecryptfs_daemon *daemon = NULL;
67 int rc;
68
69 mutex_lock(&ecryptfs_daemon_hash_mux);
70 rc = ecryptfs_find_daemon_by_euid(&daemon);
71 if (!rc) {
72 rc = -EINVAL;
73 goto out_unlock_daemon_list;
74 }
75 rc = ecryptfs_spawn_daemon(&daemon, file);
76 if (rc) {
77 printk(KERN_ERR "%s: Error attempting to spawn daemon; "
78 "rc = [%d]\n", __func__, rc);
79 goto out_unlock_daemon_list;
80 }
81 mutex_lock(&daemon->mux);
82 if (daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN) {
83 rc = -EBUSY;
84 goto out_unlock_daemon;
85 }
86 daemon->flags |= ECRYPTFS_DAEMON_MISCDEV_OPEN;
87 file->private_data = daemon;
88 atomic_inc(&ecryptfs_num_miscdev_opens);
89 out_unlock_daemon:
90 mutex_unlock(&daemon->mux);
91 out_unlock_daemon_list:
92 mutex_unlock(&ecryptfs_daemon_hash_mux);
93 return rc;
94 }
95
96 /**
97 * ecryptfs_miscdev_release
98 * @inode: inode of fs/ecryptfs/euid handle (ignored)
99 * @file: file for fs/ecryptfs/euid handle
100 *
101 * This keeps the daemon registered until the daemon sends another
102 * ioctl to fs/ecryptfs/ctl or until the kernel module unregisters.
103 *
104 * Returns zero on success; non-zero otherwise
105 */
106 static int
ecryptfs_miscdev_release(struct inode * inode,struct file * file)107 ecryptfs_miscdev_release(struct inode *inode, struct file *file)
108 {
109 struct ecryptfs_daemon *daemon = file->private_data;
110 int rc;
111
112 mutex_lock(&daemon->mux);
113 BUG_ON(!(daemon->flags & ECRYPTFS_DAEMON_MISCDEV_OPEN));
114 daemon->flags &= ~ECRYPTFS_DAEMON_MISCDEV_OPEN;
115 atomic_dec(&ecryptfs_num_miscdev_opens);
116 mutex_unlock(&daemon->mux);
117
118 mutex_lock(&ecryptfs_daemon_hash_mux);
119 rc = ecryptfs_exorcise_daemon(daemon);
120 mutex_unlock(&ecryptfs_daemon_hash_mux);
121 if (rc) {
122 printk(KERN_CRIT "%s: Fatal error whilst attempting to "
123 "shut down daemon; rc = [%d]. Please report this "
124 "bug.\n", __func__, rc);
125 BUG();
126 }
127 return rc;
128 }
129
130 /**
131 * ecryptfs_send_miscdev
132 * @data: Data to send to daemon; may be NULL
133 * @data_size: Amount of data to send to daemon
134 * @msg_ctx: Message context, which is used to handle the reply. If
135 * this is NULL, then we do not expect a reply.
136 * @msg_type: Type of message
137 * @msg_flags: Flags for message
138 * @daemon: eCryptfs daemon object
139 *
140 * Add msg_ctx to queue and then, if it exists, notify the blocked
141 * miscdevess about the data being available. Must be called with
142 * ecryptfs_daemon_hash_mux held.
143 *
144 * Returns zero on success; non-zero otherwise
145 */
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)146 int ecryptfs_send_miscdev(char *data, size_t data_size,
147 struct ecryptfs_msg_ctx *msg_ctx, u8 msg_type,
148 u16 msg_flags, struct ecryptfs_daemon *daemon)
149 {
150 struct ecryptfs_message *msg;
151
152 msg = kmalloc((sizeof(*msg) + data_size), GFP_KERNEL);
153 if (!msg)
154 return -ENOMEM;
155
156 mutex_lock(&msg_ctx->mux);
157 msg_ctx->msg = msg;
158 msg_ctx->msg->index = msg_ctx->index;
159 msg_ctx->msg->data_len = data_size;
160 msg_ctx->type = msg_type;
161 memcpy(msg_ctx->msg->data, data, data_size);
162 msg_ctx->msg_size = (sizeof(*msg_ctx->msg) + data_size);
163 list_add_tail(&msg_ctx->daemon_out_list, &daemon->msg_ctx_out_queue);
164 mutex_unlock(&msg_ctx->mux);
165
166 mutex_lock(&daemon->mux);
167 daemon->num_queued_msg_ctx++;
168 wake_up_interruptible(&daemon->wait);
169 mutex_unlock(&daemon->mux);
170
171 return 0;
172 }
173
174 /*
175 * miscdevfs packet format:
176 * Octet 0: Type
177 * Octets 1-4: network byte order msg_ctx->counter
178 * Octets 5-N0: Size of struct ecryptfs_message to follow
179 * Octets N0-N1: struct ecryptfs_message (including data)
180 *
181 * Octets 5-N1 not written if the packet type does not include a message
182 */
183 #define PKT_TYPE_SIZE 1
184 #define PKT_CTR_SIZE 4
185 #define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
186 #define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
187 + ECRYPTFS_MIN_PKT_LEN_SIZE)
188 /* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
189 #define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
190 + ECRYPTFS_MAX_PKT_LEN_SIZE \
191 + sizeof(struct ecryptfs_message) \
192 + 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
193 #define PKT_TYPE_OFFSET 0
194 #define PKT_CTR_OFFSET PKT_TYPE_SIZE
195 #define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
196
197 /**
198 * ecryptfs_miscdev_read - format and send message from queue
199 * @file: miscdevfs handle
200 * @buf: User buffer into which to copy the next message on the daemon queue
201 * @count: Amount of space available in @buf
202 * @ppos: Offset in file (ignored)
203 *
204 * Pulls the most recent message from the daemon queue, formats it for
205 * being sent via a miscdevfs handle, and copies it into @buf
206 *
207 * Returns the number of bytes copied into the user buffer
208 */
209 static ssize_t
ecryptfs_miscdev_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)210 ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
211 loff_t *ppos)
212 {
213 struct ecryptfs_daemon *daemon = file->private_data;
214 struct ecryptfs_msg_ctx *msg_ctx;
215 size_t packet_length_size;
216 char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
217 size_t i;
218 size_t total_length;
219 int rc;
220
221 mutex_lock(&daemon->mux);
222 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
223 rc = 0;
224 printk(KERN_WARNING "%s: Attempt to read from zombified "
225 "daemon\n", __func__);
226 goto out_unlock_daemon;
227 }
228 if (daemon->flags & ECRYPTFS_DAEMON_IN_READ) {
229 rc = 0;
230 goto out_unlock_daemon;
231 }
232 /* This daemon will not go away so long as this flag is set */
233 daemon->flags |= ECRYPTFS_DAEMON_IN_READ;
234 check_list:
235 if (list_empty(&daemon->msg_ctx_out_queue)) {
236 mutex_unlock(&daemon->mux);
237 rc = wait_event_interruptible(
238 daemon->wait, !list_empty(&daemon->msg_ctx_out_queue));
239 mutex_lock(&daemon->mux);
240 if (rc < 0) {
241 rc = 0;
242 goto out_unlock_daemon;
243 }
244 }
245 if (daemon->flags & ECRYPTFS_DAEMON_ZOMBIE) {
246 rc = 0;
247 goto out_unlock_daemon;
248 }
249 if (list_empty(&daemon->msg_ctx_out_queue)) {
250 /* Something else jumped in since the
251 * wait_event_interruptable() and removed the
252 * message from the queue; try again */
253 goto check_list;
254 }
255 msg_ctx = list_first_entry(&daemon->msg_ctx_out_queue,
256 struct ecryptfs_msg_ctx, daemon_out_list);
257 BUG_ON(!msg_ctx);
258 mutex_lock(&msg_ctx->mux);
259 if (msg_ctx->msg) {
260 rc = ecryptfs_write_packet_length(packet_length,
261 msg_ctx->msg_size,
262 &packet_length_size);
263 if (rc) {
264 rc = 0;
265 printk(KERN_WARNING "%s: Error writing packet length; "
266 "rc = [%d]\n", __func__, rc);
267 goto out_unlock_msg_ctx;
268 }
269 } else {
270 packet_length_size = 0;
271 msg_ctx->msg_size = 0;
272 }
273 total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
274 + msg_ctx->msg_size);
275 if (count < total_length) {
276 rc = 0;
277 printk(KERN_WARNING "%s: Only given user buffer of "
278 "size [%zd], but we need [%zd] to read the "
279 "pending message\n", __func__, count, total_length);
280 goto out_unlock_msg_ctx;
281 }
282 rc = -EFAULT;
283 if (put_user(msg_ctx->type, buf))
284 goto out_unlock_msg_ctx;
285 if (put_user(cpu_to_be32(msg_ctx->counter),
286 (__be32 __user *)(&buf[PKT_CTR_OFFSET])))
287 goto out_unlock_msg_ctx;
288 i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
289 if (msg_ctx->msg) {
290 if (copy_to_user(&buf[i], packet_length, packet_length_size))
291 goto out_unlock_msg_ctx;
292 i += packet_length_size;
293 if (copy_to_user(&buf[i], msg_ctx->msg, msg_ctx->msg_size))
294 goto out_unlock_msg_ctx;
295 i += msg_ctx->msg_size;
296 }
297 rc = i;
298 list_del(&msg_ctx->daemon_out_list);
299 kfree(msg_ctx->msg);
300 msg_ctx->msg = NULL;
301 /* We do not expect a reply from the userspace daemon for any
302 * message type other than ECRYPTFS_MSG_REQUEST */
303 if (msg_ctx->type != ECRYPTFS_MSG_REQUEST)
304 ecryptfs_msg_ctx_alloc_to_free(msg_ctx);
305 out_unlock_msg_ctx:
306 mutex_unlock(&msg_ctx->mux);
307 out_unlock_daemon:
308 daemon->flags &= ~ECRYPTFS_DAEMON_IN_READ;
309 mutex_unlock(&daemon->mux);
310 return rc;
311 }
312
313 /**
314 * ecryptfs_miscdev_response - miscdevess response to message previously sent to daemon
315 * @data: Bytes comprising struct ecryptfs_message
316 * @data_size: sizeof(struct ecryptfs_message) + data len
317 * @seq: Sequence number for miscdev response packet
318 *
319 * Returns zero on success; non-zero otherwise
320 */
ecryptfs_miscdev_response(struct ecryptfs_daemon * daemon,char * data,size_t data_size,u32 seq)321 static int ecryptfs_miscdev_response(struct ecryptfs_daemon *daemon, char *data,
322 size_t data_size, u32 seq)
323 {
324 struct ecryptfs_message *msg = (struct ecryptfs_message *)data;
325 int rc;
326
327 if ((sizeof(*msg) + msg->data_len) != data_size) {
328 printk(KERN_WARNING "%s: (sizeof(*msg) + msg->data_len) = "
329 "[%zd]; data_size = [%zd]. Invalid packet.\n", __func__,
330 (sizeof(*msg) + msg->data_len), data_size);
331 rc = -EINVAL;
332 goto out;
333 }
334 rc = ecryptfs_process_response(daemon, msg, seq);
335 if (rc)
336 printk(KERN_ERR
337 "Error processing response message; rc = [%d]\n", rc);
338 out:
339 return rc;
340 }
341
342 /**
343 * ecryptfs_miscdev_write - handle write to daemon miscdev handle
344 * @file: File for misc dev handle
345 * @buf: Buffer containing user data
346 * @count: Amount of data in @buf
347 * @ppos: Pointer to offset in file (ignored)
348 *
349 * Returns the number of bytes read from @buf
350 */
351 static ssize_t
ecryptfs_miscdev_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)352 ecryptfs_miscdev_write(struct file *file, const char __user *buf,
353 size_t count, loff_t *ppos)
354 {
355 __be32 counter_nbo;
356 u32 seq;
357 size_t packet_size, packet_size_length;
358 char *data;
359 unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
360 ssize_t rc;
361
362 if (count == 0) {
363 return 0;
364 } else if (count == MIN_NON_MSG_PKT_SIZE) {
365 /* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
366 goto memdup;
367 } else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
368 printk(KERN_WARNING "%s: Acceptable packet size range is "
369 "[%d-%zu], but amount of data written is [%zu].\n",
370 __func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
371 return -EINVAL;
372 }
373
374 if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
375 sizeof(packet_size_peek))) {
376 printk(KERN_WARNING "%s: Error while inspecting packet size\n",
377 __func__);
378 return -EFAULT;
379 }
380
381 rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
382 &packet_size_length);
383 if (rc) {
384 printk(KERN_WARNING "%s: Error parsing packet length; "
385 "rc = [%zd]\n", __func__, rc);
386 return rc;
387 }
388
389 if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
390 != count) {
391 printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
392 packet_size);
393 return -EINVAL;
394 }
395
396 memdup:
397 data = memdup_user(buf, count);
398 if (IS_ERR(data)) {
399 printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
400 __func__, PTR_ERR(data));
401 return PTR_ERR(data);
402 }
403 switch (data[PKT_TYPE_OFFSET]) {
404 case ECRYPTFS_MSG_RESPONSE:
405 if (count < (MIN_MSG_PKT_SIZE
406 + sizeof(struct ecryptfs_message))) {
407 printk(KERN_WARNING "%s: Minimum acceptable packet "
408 "size is [%zd], but amount of data written is "
409 "only [%zd]. Discarding response packet.\n",
410 __func__,
411 (MIN_MSG_PKT_SIZE
412 + sizeof(struct ecryptfs_message)), count);
413 rc = -EINVAL;
414 goto out_free;
415 }
416 memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
417 seq = be32_to_cpu(counter_nbo);
418 rc = ecryptfs_miscdev_response(file->private_data,
419 &data[PKT_LEN_OFFSET + packet_size_length],
420 packet_size, seq);
421 if (rc) {
422 printk(KERN_WARNING "%s: Failed to deliver miscdev "
423 "response to requesting operation; rc = [%zd]\n",
424 __func__, rc);
425 goto out_free;
426 }
427 break;
428 case ECRYPTFS_MSG_HELO:
429 case ECRYPTFS_MSG_QUIT:
430 break;
431 default:
432 ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
433 "message of unrecognized type [%d]\n",
434 data[0]);
435 rc = -EINVAL;
436 goto out_free;
437 }
438 rc = count;
439 out_free:
440 kfree(data);
441 return rc;
442 }
443
444
445 static const struct file_operations ecryptfs_miscdev_fops = {
446 .owner = THIS_MODULE,
447 .open = ecryptfs_miscdev_open,
448 .poll = ecryptfs_miscdev_poll,
449 .read = ecryptfs_miscdev_read,
450 .write = ecryptfs_miscdev_write,
451 .release = ecryptfs_miscdev_release,
452 .llseek = noop_llseek,
453 };
454
455 static struct miscdevice ecryptfs_miscdev = {
456 .minor = MISC_DYNAMIC_MINOR,
457 .name = "ecryptfs",
458 .fops = &ecryptfs_miscdev_fops
459 };
460
461 /**
462 * ecryptfs_init_ecryptfs_miscdev
463 *
464 * Messages sent to the userspace daemon from the kernel are placed on
465 * a queue associated with the daemon. The next read against the
466 * miscdev handle by that daemon will return the oldest message placed
467 * on the message queue for the daemon.
468 *
469 * Returns zero on success; non-zero otherwise
470 */
ecryptfs_init_ecryptfs_miscdev(void)471 int __init ecryptfs_init_ecryptfs_miscdev(void)
472 {
473 int rc;
474
475 atomic_set(&ecryptfs_num_miscdev_opens, 0);
476 rc = misc_register(&ecryptfs_miscdev);
477 if (rc)
478 printk(KERN_ERR "%s: Failed to register miscellaneous device "
479 "for communications with userspace daemons; rc = [%d]\n",
480 __func__, rc);
481 return rc;
482 }
483
484 /**
485 * ecryptfs_destroy_ecryptfs_miscdev
486 *
487 * All of the daemons must be exorcised prior to calling this
488 * function.
489 */
ecryptfs_destroy_ecryptfs_miscdev(void)490 void ecryptfs_destroy_ecryptfs_miscdev(void)
491 {
492 BUG_ON(atomic_read(&ecryptfs_num_miscdev_opens) != 0);
493 misc_deregister(&ecryptfs_miscdev);
494 }
495