xref: /openbmc/linux/fs/ecryptfs/main.c (revision 612a462a)
1 /**
2  * eCryptfs: Linux filesystem encryption layer
3  *
4  * Copyright (C) 1997-2003 Erez Zadok
5  * Copyright (C) 2001-2003 Stony Brook University
6  * Copyright (C) 2004-2007 International Business Machines Corp.
7  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
8  *              Michael C. Thompson <mcthomps@us.ibm.com>
9  *              Tyler Hicks <tyhicks@ou.edu>
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public License as
13  * published by the Free Software Foundation; either version 2 of the
14  * License, or (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful, but
17  * WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19  * General Public License for more details.
20  *
21  * You should have received a copy of the GNU General Public License
22  * along with this program; if not, write to the Free Software
23  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
24  * 02111-1307, USA.
25  */
26 
27 #include <linux/dcache.h>
28 #include <linux/file.h>
29 #include <linux/module.h>
30 #include <linux/namei.h>
31 #include <linux/skbuff.h>
32 #include <linux/mount.h>
33 #include <linux/pagemap.h>
34 #include <linux/key.h>
35 #include <linux/parser.h>
36 #include <linux/fs_stack.h>
37 #include <linux/slab.h>
38 #include <linux/magic.h>
39 #include "ecryptfs_kernel.h"
40 
41 /**
42  * Module parameter that defines the ecryptfs_verbosity level.
43  */
44 int ecryptfs_verbosity = 0;
45 
46 module_param(ecryptfs_verbosity, int, 0);
47 MODULE_PARM_DESC(ecryptfs_verbosity,
48 		 "Initial verbosity level (0 or 1; defaults to "
49 		 "0, which is Quiet)");
50 
51 /**
52  * Module parameter that defines the number of message buffer elements
53  */
54 unsigned int ecryptfs_message_buf_len = ECRYPTFS_DEFAULT_MSG_CTX_ELEMS;
55 
56 module_param(ecryptfs_message_buf_len, uint, 0);
57 MODULE_PARM_DESC(ecryptfs_message_buf_len,
58 		 "Number of message buffer elements");
59 
60 /**
61  * Module parameter that defines the maximum guaranteed amount of time to wait
62  * for a response from ecryptfsd.  The actual sleep time will be, more than
63  * likely, a small amount greater than this specified value, but only less if
64  * the message successfully arrives.
65  */
66 signed long ecryptfs_message_wait_timeout = ECRYPTFS_MAX_MSG_CTX_TTL / HZ;
67 
68 module_param(ecryptfs_message_wait_timeout, long, 0);
69 MODULE_PARM_DESC(ecryptfs_message_wait_timeout,
70 		 "Maximum number of seconds that an operation will "
71 		 "sleep while waiting for a message response from "
72 		 "userspace");
73 
74 /**
75  * Module parameter that is an estimate of the maximum number of users
76  * that will be concurrently using eCryptfs. Set this to the right
77  * value to balance performance and memory use.
78  */
79 unsigned int ecryptfs_number_of_users = ECRYPTFS_DEFAULT_NUM_USERS;
80 
81 module_param(ecryptfs_number_of_users, uint, 0);
82 MODULE_PARM_DESC(ecryptfs_number_of_users, "An estimate of the number of "
83 		 "concurrent users of eCryptfs");
84 
85 void __ecryptfs_printk(const char *fmt, ...)
86 {
87 	va_list args;
88 	va_start(args, fmt);
89 	if (fmt[1] == '7') { /* KERN_DEBUG */
90 		if (ecryptfs_verbosity >= 1)
91 			vprintk(fmt, args);
92 	} else
93 		vprintk(fmt, args);
94 	va_end(args);
95 }
96 
97 /**
98  * ecryptfs_init_lower_file
99  * @ecryptfs_dentry: Fully initialized eCryptfs dentry object, with
100  *                   the lower dentry and the lower mount set
101  *
102  * eCryptfs only ever keeps a single open file for every lower
103  * inode. All I/O operations to the lower inode occur through that
104  * file. When the first eCryptfs dentry that interposes with the first
105  * lower dentry for that inode is created, this function creates the
106  * lower file struct and associates it with the eCryptfs
107  * inode. When all eCryptfs files associated with the inode are released, the
108  * file is closed.
109  *
110  * The lower file will be opened with read/write permissions, if
111  * possible. Otherwise, it is opened read-only.
112  *
113  * This function does nothing if a lower file is already
114  * associated with the eCryptfs inode.
115  *
116  * Returns zero on success; non-zero otherwise
117  */
118 static int ecryptfs_init_lower_file(struct dentry *dentry,
119 				    struct file **lower_file)
120 {
121 	const struct cred *cred = current_cred();
122 	struct path *path = ecryptfs_dentry_to_lower_path(dentry);
123 	int rc;
124 
125 	rc = ecryptfs_privileged_open(lower_file, path->dentry, path->mnt,
126 				      cred);
127 	if (rc) {
128 		printk(KERN_ERR "Error opening lower file "
129 		       "for lower_dentry [0x%p] and lower_mnt [0x%p]; "
130 		       "rc = [%d]\n", path->dentry, path->mnt, rc);
131 		(*lower_file) = NULL;
132 	}
133 	return rc;
134 }
135 
136 int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode)
137 {
138 	struct ecryptfs_inode_info *inode_info;
139 	int count, rc = 0;
140 
141 	inode_info = ecryptfs_inode_to_private(inode);
142 	mutex_lock(&inode_info->lower_file_mutex);
143 	count = atomic_inc_return(&inode_info->lower_file_count);
144 	if (WARN_ON_ONCE(count < 1))
145 		rc = -EINVAL;
146 	else if (count == 1) {
147 		rc = ecryptfs_init_lower_file(dentry,
148 					      &inode_info->lower_file);
149 		if (rc)
150 			atomic_set(&inode_info->lower_file_count, 0);
151 	}
152 	mutex_unlock(&inode_info->lower_file_mutex);
153 	return rc;
154 }
155 
156 void ecryptfs_put_lower_file(struct inode *inode)
157 {
158 	struct ecryptfs_inode_info *inode_info;
159 
160 	inode_info = ecryptfs_inode_to_private(inode);
161 	if (atomic_dec_and_mutex_lock(&inode_info->lower_file_count,
162 				      &inode_info->lower_file_mutex)) {
163 		filemap_write_and_wait(inode->i_mapping);
164 		fput(inode_info->lower_file);
165 		inode_info->lower_file = NULL;
166 		mutex_unlock(&inode_info->lower_file_mutex);
167 	}
168 }
169 
170 enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig,
171        ecryptfs_opt_cipher, ecryptfs_opt_ecryptfs_cipher,
172        ecryptfs_opt_ecryptfs_key_bytes,
173        ecryptfs_opt_passthrough, ecryptfs_opt_xattr_metadata,
174        ecryptfs_opt_encrypted_view, ecryptfs_opt_fnek_sig,
175        ecryptfs_opt_fn_cipher, ecryptfs_opt_fn_cipher_key_bytes,
176        ecryptfs_opt_unlink_sigs, ecryptfs_opt_mount_auth_tok_only,
177        ecryptfs_opt_check_dev_ruid,
178        ecryptfs_opt_err };
179 
180 static const match_table_t tokens = {
181 	{ecryptfs_opt_sig, "sig=%s"},
182 	{ecryptfs_opt_ecryptfs_sig, "ecryptfs_sig=%s"},
183 	{ecryptfs_opt_cipher, "cipher=%s"},
184 	{ecryptfs_opt_ecryptfs_cipher, "ecryptfs_cipher=%s"},
185 	{ecryptfs_opt_ecryptfs_key_bytes, "ecryptfs_key_bytes=%u"},
186 	{ecryptfs_opt_passthrough, "ecryptfs_passthrough"},
187 	{ecryptfs_opt_xattr_metadata, "ecryptfs_xattr_metadata"},
188 	{ecryptfs_opt_encrypted_view, "ecryptfs_encrypted_view"},
189 	{ecryptfs_opt_fnek_sig, "ecryptfs_fnek_sig=%s"},
190 	{ecryptfs_opt_fn_cipher, "ecryptfs_fn_cipher=%s"},
191 	{ecryptfs_opt_fn_cipher_key_bytes, "ecryptfs_fn_key_bytes=%u"},
192 	{ecryptfs_opt_unlink_sigs, "ecryptfs_unlink_sigs"},
193 	{ecryptfs_opt_mount_auth_tok_only, "ecryptfs_mount_auth_tok_only"},
194 	{ecryptfs_opt_check_dev_ruid, "ecryptfs_check_dev_ruid"},
195 	{ecryptfs_opt_err, NULL}
196 };
197 
198 static int ecryptfs_init_global_auth_toks(
199 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
200 {
201 	struct ecryptfs_global_auth_tok *global_auth_tok;
202 	struct ecryptfs_auth_tok *auth_tok;
203 	int rc = 0;
204 
205 	list_for_each_entry(global_auth_tok,
206 			    &mount_crypt_stat->global_auth_tok_list,
207 			    mount_crypt_stat_list) {
208 		rc = ecryptfs_keyring_auth_tok_for_sig(
209 			&global_auth_tok->global_auth_tok_key, &auth_tok,
210 			global_auth_tok->sig);
211 		if (rc) {
212 			printk(KERN_ERR "Could not find valid key in user "
213 			       "session keyring for sig specified in mount "
214 			       "option: [%s]\n", global_auth_tok->sig);
215 			global_auth_tok->flags |= ECRYPTFS_AUTH_TOK_INVALID;
216 			goto out;
217 		} else {
218 			global_auth_tok->flags &= ~ECRYPTFS_AUTH_TOK_INVALID;
219 			up_write(&(global_auth_tok->global_auth_tok_key)->sem);
220 		}
221 	}
222 out:
223 	return rc;
224 }
225 
226 static void ecryptfs_init_mount_crypt_stat(
227 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
228 {
229 	memset((void *)mount_crypt_stat, 0,
230 	       sizeof(struct ecryptfs_mount_crypt_stat));
231 	INIT_LIST_HEAD(&mount_crypt_stat->global_auth_tok_list);
232 	mutex_init(&mount_crypt_stat->global_auth_tok_list_mutex);
233 	mount_crypt_stat->flags |= ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED;
234 }
235 
236 /**
237  * ecryptfs_parse_options
238  * @sb: The ecryptfs super block
239  * @options: The options passed to the kernel
240  * @check_ruid: set to 1 if device uid should be checked against the ruid
241  *
242  * Parse mount options:
243  * debug=N 	   - ecryptfs_verbosity level for debug output
244  * sig=XXX	   - description(signature) of the key to use
245  *
246  * Returns the dentry object of the lower-level (lower/interposed)
247  * directory; We want to mount our stackable file system on top of
248  * that lower directory.
249  *
250  * The signature of the key to use must be the description of a key
251  * already in the keyring. Mounting will fail if the key can not be
252  * found.
253  *
254  * Returns zero on success; non-zero on error
255  */
256 static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
257 				  uid_t *check_ruid)
258 {
259 	char *p;
260 	int rc = 0;
261 	int sig_set = 0;
262 	int cipher_name_set = 0;
263 	int fn_cipher_name_set = 0;
264 	int cipher_key_bytes;
265 	int cipher_key_bytes_set = 0;
266 	int fn_cipher_key_bytes;
267 	int fn_cipher_key_bytes_set = 0;
268 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
269 		&sbi->mount_crypt_stat;
270 	substring_t args[MAX_OPT_ARGS];
271 	int token;
272 	char *sig_src;
273 	char *cipher_name_dst;
274 	char *cipher_name_src;
275 	char *fn_cipher_name_dst;
276 	char *fn_cipher_name_src;
277 	char *fnek_dst;
278 	char *fnek_src;
279 	char *cipher_key_bytes_src;
280 	char *fn_cipher_key_bytes_src;
281 	u8 cipher_code;
282 
283 	*check_ruid = 0;
284 
285 	if (!options) {
286 		rc = -EINVAL;
287 		goto out;
288 	}
289 	ecryptfs_init_mount_crypt_stat(mount_crypt_stat);
290 	while ((p = strsep(&options, ",")) != NULL) {
291 		if (!*p)
292 			continue;
293 		token = match_token(p, tokens, args);
294 		switch (token) {
295 		case ecryptfs_opt_sig:
296 		case ecryptfs_opt_ecryptfs_sig:
297 			sig_src = args[0].from;
298 			rc = ecryptfs_add_global_auth_tok(mount_crypt_stat,
299 							  sig_src, 0);
300 			if (rc) {
301 				printk(KERN_ERR "Error attempting to register "
302 				       "global sig; rc = [%d]\n", rc);
303 				goto out;
304 			}
305 			sig_set = 1;
306 			break;
307 		case ecryptfs_opt_cipher:
308 		case ecryptfs_opt_ecryptfs_cipher:
309 			cipher_name_src = args[0].from;
310 			cipher_name_dst =
311 				mount_crypt_stat->
312 				global_default_cipher_name;
313 			strncpy(cipher_name_dst, cipher_name_src,
314 				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
315 			cipher_name_dst[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
316 			cipher_name_set = 1;
317 			break;
318 		case ecryptfs_opt_ecryptfs_key_bytes:
319 			cipher_key_bytes_src = args[0].from;
320 			cipher_key_bytes =
321 				(int)simple_strtol(cipher_key_bytes_src,
322 						   &cipher_key_bytes_src, 0);
323 			mount_crypt_stat->global_default_cipher_key_size =
324 				cipher_key_bytes;
325 			cipher_key_bytes_set = 1;
326 			break;
327 		case ecryptfs_opt_passthrough:
328 			mount_crypt_stat->flags |=
329 				ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED;
330 			break;
331 		case ecryptfs_opt_xattr_metadata:
332 			mount_crypt_stat->flags |=
333 				ECRYPTFS_XATTR_METADATA_ENABLED;
334 			break;
335 		case ecryptfs_opt_encrypted_view:
336 			mount_crypt_stat->flags |=
337 				ECRYPTFS_XATTR_METADATA_ENABLED;
338 			mount_crypt_stat->flags |=
339 				ECRYPTFS_ENCRYPTED_VIEW_ENABLED;
340 			break;
341 		case ecryptfs_opt_fnek_sig:
342 			fnek_src = args[0].from;
343 			fnek_dst =
344 				mount_crypt_stat->global_default_fnek_sig;
345 			strncpy(fnek_dst, fnek_src, ECRYPTFS_SIG_SIZE_HEX);
346 			mount_crypt_stat->global_default_fnek_sig[
347 				ECRYPTFS_SIG_SIZE_HEX] = '\0';
348 			rc = ecryptfs_add_global_auth_tok(
349 				mount_crypt_stat,
350 				mount_crypt_stat->global_default_fnek_sig,
351 				ECRYPTFS_AUTH_TOK_FNEK);
352 			if (rc) {
353 				printk(KERN_ERR "Error attempting to register "
354 				       "global fnek sig [%s]; rc = [%d]\n",
355 				       mount_crypt_stat->global_default_fnek_sig,
356 				       rc);
357 				goto out;
358 			}
359 			mount_crypt_stat->flags |=
360 				(ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES
361 				 | ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK);
362 			break;
363 		case ecryptfs_opt_fn_cipher:
364 			fn_cipher_name_src = args[0].from;
365 			fn_cipher_name_dst =
366 				mount_crypt_stat->global_default_fn_cipher_name;
367 			strncpy(fn_cipher_name_dst, fn_cipher_name_src,
368 				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
369 			mount_crypt_stat->global_default_fn_cipher_name[
370 				ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
371 			fn_cipher_name_set = 1;
372 			break;
373 		case ecryptfs_opt_fn_cipher_key_bytes:
374 			fn_cipher_key_bytes_src = args[0].from;
375 			fn_cipher_key_bytes =
376 				(int)simple_strtol(fn_cipher_key_bytes_src,
377 						   &fn_cipher_key_bytes_src, 0);
378 			mount_crypt_stat->global_default_fn_cipher_key_bytes =
379 				fn_cipher_key_bytes;
380 			fn_cipher_key_bytes_set = 1;
381 			break;
382 		case ecryptfs_opt_unlink_sigs:
383 			mount_crypt_stat->flags |= ECRYPTFS_UNLINK_SIGS;
384 			break;
385 		case ecryptfs_opt_mount_auth_tok_only:
386 			mount_crypt_stat->flags |=
387 				ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY;
388 			break;
389 		case ecryptfs_opt_check_dev_ruid:
390 			*check_ruid = 1;
391 			break;
392 		case ecryptfs_opt_err:
393 		default:
394 			printk(KERN_WARNING
395 			       "%s: eCryptfs: unrecognized option [%s]\n",
396 			       __func__, p);
397 		}
398 	}
399 	if (!sig_set) {
400 		rc = -EINVAL;
401 		ecryptfs_printk(KERN_ERR, "You must supply at least one valid "
402 				"auth tok signature as a mount "
403 				"parameter; see the eCryptfs README\n");
404 		goto out;
405 	}
406 	if (!cipher_name_set) {
407 		int cipher_name_len = strlen(ECRYPTFS_DEFAULT_CIPHER);
408 
409 		BUG_ON(cipher_name_len > ECRYPTFS_MAX_CIPHER_NAME_SIZE);
410 		strcpy(mount_crypt_stat->global_default_cipher_name,
411 		       ECRYPTFS_DEFAULT_CIPHER);
412 	}
413 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
414 	    && !fn_cipher_name_set)
415 		strcpy(mount_crypt_stat->global_default_fn_cipher_name,
416 		       mount_crypt_stat->global_default_cipher_name);
417 	if (!cipher_key_bytes_set)
418 		mount_crypt_stat->global_default_cipher_key_size = 0;
419 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
420 	    && !fn_cipher_key_bytes_set)
421 		mount_crypt_stat->global_default_fn_cipher_key_bytes =
422 			mount_crypt_stat->global_default_cipher_key_size;
423 
424 	cipher_code = ecryptfs_code_for_cipher_string(
425 		mount_crypt_stat->global_default_cipher_name,
426 		mount_crypt_stat->global_default_cipher_key_size);
427 	if (!cipher_code) {
428 		ecryptfs_printk(KERN_ERR,
429 				"eCryptfs doesn't support cipher: %s",
430 				mount_crypt_stat->global_default_cipher_name);
431 		rc = -EINVAL;
432 		goto out;
433 	}
434 
435 	mutex_lock(&key_tfm_list_mutex);
436 	if (!ecryptfs_tfm_exists(mount_crypt_stat->global_default_cipher_name,
437 				 NULL)) {
438 		rc = ecryptfs_add_new_key_tfm(
439 			NULL, mount_crypt_stat->global_default_cipher_name,
440 			mount_crypt_stat->global_default_cipher_key_size);
441 		if (rc) {
442 			printk(KERN_ERR "Error attempting to initialize "
443 			       "cipher with name = [%s] and key size = [%td]; "
444 			       "rc = [%d]\n",
445 			       mount_crypt_stat->global_default_cipher_name,
446 			       mount_crypt_stat->global_default_cipher_key_size,
447 			       rc);
448 			rc = -EINVAL;
449 			mutex_unlock(&key_tfm_list_mutex);
450 			goto out;
451 		}
452 	}
453 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
454 	    && !ecryptfs_tfm_exists(
455 		    mount_crypt_stat->global_default_fn_cipher_name, NULL)) {
456 		rc = ecryptfs_add_new_key_tfm(
457 			NULL, mount_crypt_stat->global_default_fn_cipher_name,
458 			mount_crypt_stat->global_default_fn_cipher_key_bytes);
459 		if (rc) {
460 			printk(KERN_ERR "Error attempting to initialize "
461 			       "cipher with name = [%s] and key size = [%td]; "
462 			       "rc = [%d]\n",
463 			       mount_crypt_stat->global_default_fn_cipher_name,
464 			       mount_crypt_stat->global_default_fn_cipher_key_bytes,
465 			       rc);
466 			rc = -EINVAL;
467 			mutex_unlock(&key_tfm_list_mutex);
468 			goto out;
469 		}
470 	}
471 	mutex_unlock(&key_tfm_list_mutex);
472 	rc = ecryptfs_init_global_auth_toks(mount_crypt_stat);
473 	if (rc)
474 		printk(KERN_WARNING "One or more global auth toks could not "
475 		       "properly register; rc = [%d]\n", rc);
476 out:
477 	return rc;
478 }
479 
480 struct kmem_cache *ecryptfs_sb_info_cache;
481 static struct file_system_type ecryptfs_fs_type;
482 
483 /**
484  * ecryptfs_get_sb
485  * @fs_type
486  * @flags
487  * @dev_name: The path to mount over
488  * @raw_data: The options passed into the kernel
489  */
490 static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags,
491 			const char *dev_name, void *raw_data)
492 {
493 	struct super_block *s;
494 	struct ecryptfs_sb_info *sbi;
495 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
496 	struct ecryptfs_dentry_info *root_info;
497 	const char *err = "Getting sb failed";
498 	struct inode *inode;
499 	struct path path;
500 	uid_t check_ruid;
501 	int rc;
502 
503 	sbi = kmem_cache_zalloc(ecryptfs_sb_info_cache, GFP_KERNEL);
504 	if (!sbi) {
505 		rc = -ENOMEM;
506 		goto out;
507 	}
508 
509 	rc = ecryptfs_parse_options(sbi, raw_data, &check_ruid);
510 	if (rc) {
511 		err = "Error parsing options";
512 		goto out;
513 	}
514 	mount_crypt_stat = &sbi->mount_crypt_stat;
515 
516 	s = sget(fs_type, NULL, set_anon_super, flags, NULL);
517 	if (IS_ERR(s)) {
518 		rc = PTR_ERR(s);
519 		goto out;
520 	}
521 
522 	rc = super_setup_bdi(s);
523 	if (rc)
524 		goto out1;
525 
526 	ecryptfs_set_superblock_private(s, sbi);
527 
528 	/* ->kill_sb() will take care of sbi after that point */
529 	sbi = NULL;
530 	s->s_op = &ecryptfs_sops;
531 	s->s_xattr = ecryptfs_xattr_handlers;
532 	s->s_d_op = &ecryptfs_dops;
533 
534 	err = "Reading sb failed";
535 	rc = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
536 	if (rc) {
537 		ecryptfs_printk(KERN_WARNING, "kern_path() failed\n");
538 		goto out1;
539 	}
540 	if (path.dentry->d_sb->s_type == &ecryptfs_fs_type) {
541 		rc = -EINVAL;
542 		printk(KERN_ERR "Mount on filesystem of type "
543 			"eCryptfs explicitly disallowed due to "
544 			"known incompatibilities\n");
545 		goto out_free;
546 	}
547 
548 	if (check_ruid && !uid_eq(d_inode(path.dentry)->i_uid, current_uid())) {
549 		rc = -EPERM;
550 		printk(KERN_ERR "Mount of device (uid: %d) not owned by "
551 		       "requested user (uid: %d)\n",
552 			i_uid_read(d_inode(path.dentry)),
553 			from_kuid(&init_user_ns, current_uid()));
554 		goto out_free;
555 	}
556 
557 	ecryptfs_set_superblock_lower(s, path.dentry->d_sb);
558 
559 	/**
560 	 * Set the POSIX ACL flag based on whether they're enabled in the lower
561 	 * mount.
562 	 */
563 	s->s_flags = flags & ~MS_POSIXACL;
564 	s->s_flags |= path.dentry->d_sb->s_flags & MS_POSIXACL;
565 
566 	/**
567 	 * Force a read-only eCryptfs mount when:
568 	 *   1) The lower mount is ro
569 	 *   2) The ecryptfs_encrypted_view mount option is specified
570 	 */
571 	if (sb_rdonly(path.dentry->d_sb) || mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
572 		s->s_flags |= MS_RDONLY;
573 
574 	s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
575 	s->s_blocksize = path.dentry->d_sb->s_blocksize;
576 	s->s_magic = ECRYPTFS_SUPER_MAGIC;
577 	s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
578 
579 	rc = -EINVAL;
580 	if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
581 		pr_err("eCryptfs: maximum fs stacking depth exceeded\n");
582 		goto out_free;
583 	}
584 
585 	inode = ecryptfs_get_inode(d_inode(path.dentry), s);
586 	rc = PTR_ERR(inode);
587 	if (IS_ERR(inode))
588 		goto out_free;
589 
590 	s->s_root = d_make_root(inode);
591 	if (!s->s_root) {
592 		rc = -ENOMEM;
593 		goto out_free;
594 	}
595 
596 	rc = -ENOMEM;
597 	root_info = kmem_cache_zalloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
598 	if (!root_info)
599 		goto out_free;
600 
601 	/* ->kill_sb() will take care of root_info */
602 	ecryptfs_set_dentry_private(s->s_root, root_info);
603 	root_info->lower_path = path;
604 
605 	s->s_flags |= MS_ACTIVE;
606 	return dget(s->s_root);
607 
608 out_free:
609 	path_put(&path);
610 out1:
611 	deactivate_locked_super(s);
612 out:
613 	if (sbi) {
614 		ecryptfs_destroy_mount_crypt_stat(&sbi->mount_crypt_stat);
615 		kmem_cache_free(ecryptfs_sb_info_cache, sbi);
616 	}
617 	printk(KERN_ERR "%s; rc = [%d]\n", err, rc);
618 	return ERR_PTR(rc);
619 }
620 
621 /**
622  * ecryptfs_kill_block_super
623  * @sb: The ecryptfs super block
624  *
625  * Used to bring the superblock down and free the private data.
626  */
627 static void ecryptfs_kill_block_super(struct super_block *sb)
628 {
629 	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
630 	kill_anon_super(sb);
631 	if (!sb_info)
632 		return;
633 	ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
634 	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
635 }
636 
637 static struct file_system_type ecryptfs_fs_type = {
638 	.owner = THIS_MODULE,
639 	.name = "ecryptfs",
640 	.mount = ecryptfs_mount,
641 	.kill_sb = ecryptfs_kill_block_super,
642 	.fs_flags = 0
643 };
644 MODULE_ALIAS_FS("ecryptfs");
645 
646 /**
647  * inode_info_init_once
648  *
649  * Initializes the ecryptfs_inode_info_cache when it is created
650  */
651 static void
652 inode_info_init_once(void *vptr)
653 {
654 	struct ecryptfs_inode_info *ei = (struct ecryptfs_inode_info *)vptr;
655 
656 	inode_init_once(&ei->vfs_inode);
657 }
658 
659 static struct ecryptfs_cache_info {
660 	struct kmem_cache **cache;
661 	const char *name;
662 	size_t size;
663 	unsigned long flags;
664 	void (*ctor)(void *obj);
665 } ecryptfs_cache_infos[] = {
666 	{
667 		.cache = &ecryptfs_auth_tok_list_item_cache,
668 		.name = "ecryptfs_auth_tok_list_item",
669 		.size = sizeof(struct ecryptfs_auth_tok_list_item),
670 	},
671 	{
672 		.cache = &ecryptfs_file_info_cache,
673 		.name = "ecryptfs_file_cache",
674 		.size = sizeof(struct ecryptfs_file_info),
675 	},
676 	{
677 		.cache = &ecryptfs_dentry_info_cache,
678 		.name = "ecryptfs_dentry_info_cache",
679 		.size = sizeof(struct ecryptfs_dentry_info),
680 	},
681 	{
682 		.cache = &ecryptfs_inode_info_cache,
683 		.name = "ecryptfs_inode_cache",
684 		.size = sizeof(struct ecryptfs_inode_info),
685 		.flags = SLAB_ACCOUNT,
686 		.ctor = inode_info_init_once,
687 	},
688 	{
689 		.cache = &ecryptfs_sb_info_cache,
690 		.name = "ecryptfs_sb_cache",
691 		.size = sizeof(struct ecryptfs_sb_info),
692 	},
693 	{
694 		.cache = &ecryptfs_header_cache,
695 		.name = "ecryptfs_headers",
696 		.size = PAGE_SIZE,
697 	},
698 	{
699 		.cache = &ecryptfs_xattr_cache,
700 		.name = "ecryptfs_xattr_cache",
701 		.size = PAGE_SIZE,
702 	},
703 	{
704 		.cache = &ecryptfs_key_record_cache,
705 		.name = "ecryptfs_key_record_cache",
706 		.size = sizeof(struct ecryptfs_key_record),
707 	},
708 	{
709 		.cache = &ecryptfs_key_sig_cache,
710 		.name = "ecryptfs_key_sig_cache",
711 		.size = sizeof(struct ecryptfs_key_sig),
712 	},
713 	{
714 		.cache = &ecryptfs_global_auth_tok_cache,
715 		.name = "ecryptfs_global_auth_tok_cache",
716 		.size = sizeof(struct ecryptfs_global_auth_tok),
717 	},
718 	{
719 		.cache = &ecryptfs_key_tfm_cache,
720 		.name = "ecryptfs_key_tfm_cache",
721 		.size = sizeof(struct ecryptfs_key_tfm),
722 	},
723 };
724 
725 static void ecryptfs_free_kmem_caches(void)
726 {
727 	int i;
728 
729 	/*
730 	 * Make sure all delayed rcu free inodes are flushed before we
731 	 * destroy cache.
732 	 */
733 	rcu_barrier();
734 
735 	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
736 		struct ecryptfs_cache_info *info;
737 
738 		info = &ecryptfs_cache_infos[i];
739 		kmem_cache_destroy(*(info->cache));
740 	}
741 }
742 
743 /**
744  * ecryptfs_init_kmem_caches
745  *
746  * Returns zero on success; non-zero otherwise
747  */
748 static int ecryptfs_init_kmem_caches(void)
749 {
750 	int i;
751 
752 	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
753 		struct ecryptfs_cache_info *info;
754 
755 		info = &ecryptfs_cache_infos[i];
756 		*(info->cache) = kmem_cache_create(info->name, info->size, 0,
757 				SLAB_HWCACHE_ALIGN | info->flags, info->ctor);
758 		if (!*(info->cache)) {
759 			ecryptfs_free_kmem_caches();
760 			ecryptfs_printk(KERN_WARNING, "%s: "
761 					"kmem_cache_create failed\n",
762 					info->name);
763 			return -ENOMEM;
764 		}
765 	}
766 	return 0;
767 }
768 
769 static struct kobject *ecryptfs_kobj;
770 
771 static ssize_t version_show(struct kobject *kobj,
772 			    struct kobj_attribute *attr, char *buff)
773 {
774 	return snprintf(buff, PAGE_SIZE, "%d\n", ECRYPTFS_VERSIONING_MASK);
775 }
776 
777 static struct kobj_attribute version_attr = __ATTR_RO(version);
778 
779 static struct attribute *attributes[] = {
780 	&version_attr.attr,
781 	NULL,
782 };
783 
784 static struct attribute_group attr_group = {
785 	.attrs = attributes,
786 };
787 
788 static int do_sysfs_registration(void)
789 {
790 	int rc;
791 
792 	ecryptfs_kobj = kobject_create_and_add("ecryptfs", fs_kobj);
793 	if (!ecryptfs_kobj) {
794 		printk(KERN_ERR "Unable to create ecryptfs kset\n");
795 		rc = -ENOMEM;
796 		goto out;
797 	}
798 	rc = sysfs_create_group(ecryptfs_kobj, &attr_group);
799 	if (rc) {
800 		printk(KERN_ERR
801 		       "Unable to create ecryptfs version attributes\n");
802 		kobject_put(ecryptfs_kobj);
803 	}
804 out:
805 	return rc;
806 }
807 
808 static void do_sysfs_unregistration(void)
809 {
810 	sysfs_remove_group(ecryptfs_kobj, &attr_group);
811 	kobject_put(ecryptfs_kobj);
812 }
813 
814 static int __init ecryptfs_init(void)
815 {
816 	int rc;
817 
818 	if (ECRYPTFS_DEFAULT_EXTENT_SIZE > PAGE_SIZE) {
819 		rc = -EINVAL;
820 		ecryptfs_printk(KERN_ERR, "The eCryptfs extent size is "
821 				"larger than the host's page size, and so "
822 				"eCryptfs cannot run on this system. The "
823 				"default eCryptfs extent size is [%u] bytes; "
824 				"the page size is [%lu] bytes.\n",
825 				ECRYPTFS_DEFAULT_EXTENT_SIZE,
826 				(unsigned long)PAGE_SIZE);
827 		goto out;
828 	}
829 	rc = ecryptfs_init_kmem_caches();
830 	if (rc) {
831 		printk(KERN_ERR
832 		       "Failed to allocate one or more kmem_cache objects\n");
833 		goto out;
834 	}
835 	rc = do_sysfs_registration();
836 	if (rc) {
837 		printk(KERN_ERR "sysfs registration failed\n");
838 		goto out_free_kmem_caches;
839 	}
840 	rc = ecryptfs_init_kthread();
841 	if (rc) {
842 		printk(KERN_ERR "%s: kthread initialization failed; "
843 		       "rc = [%d]\n", __func__, rc);
844 		goto out_do_sysfs_unregistration;
845 	}
846 	rc = ecryptfs_init_messaging();
847 	if (rc) {
848 		printk(KERN_ERR "Failure occurred while attempting to "
849 				"initialize the communications channel to "
850 				"ecryptfsd\n");
851 		goto out_destroy_kthread;
852 	}
853 	rc = ecryptfs_init_crypto();
854 	if (rc) {
855 		printk(KERN_ERR "Failure whilst attempting to init crypto; "
856 		       "rc = [%d]\n", rc);
857 		goto out_release_messaging;
858 	}
859 	rc = register_filesystem(&ecryptfs_fs_type);
860 	if (rc) {
861 		printk(KERN_ERR "Failed to register filesystem\n");
862 		goto out_destroy_crypto;
863 	}
864 	if (ecryptfs_verbosity > 0)
865 		printk(KERN_CRIT "eCryptfs verbosity set to %d. Secret values "
866 			"will be written to the syslog!\n", ecryptfs_verbosity);
867 
868 	goto out;
869 out_destroy_crypto:
870 	ecryptfs_destroy_crypto();
871 out_release_messaging:
872 	ecryptfs_release_messaging();
873 out_destroy_kthread:
874 	ecryptfs_destroy_kthread();
875 out_do_sysfs_unregistration:
876 	do_sysfs_unregistration();
877 out_free_kmem_caches:
878 	ecryptfs_free_kmem_caches();
879 out:
880 	return rc;
881 }
882 
883 static void __exit ecryptfs_exit(void)
884 {
885 	int rc;
886 
887 	rc = ecryptfs_destroy_crypto();
888 	if (rc)
889 		printk(KERN_ERR "Failure whilst attempting to destroy crypto; "
890 		       "rc = [%d]\n", rc);
891 	ecryptfs_release_messaging();
892 	ecryptfs_destroy_kthread();
893 	do_sysfs_unregistration();
894 	unregister_filesystem(&ecryptfs_fs_type);
895 	ecryptfs_free_kmem_caches();
896 }
897 
898 MODULE_AUTHOR("Michael A. Halcrow <mhalcrow@us.ibm.com>");
899 MODULE_DESCRIPTION("eCryptfs");
900 
901 MODULE_LICENSE("GPL");
902 
903 module_init(ecryptfs_init)
904 module_exit(ecryptfs_exit)
905