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