xref: /openbmc/linux/fs/ecryptfs/main.c (revision c4f7ac64)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * eCryptfs: Linux filesystem encryption layer
4  *
5  * Copyright (C) 1997-2003 Erez Zadok
6  * Copyright (C) 2001-2003 Stony Brook University
7  * Copyright (C) 2004-2007 International Business Machines Corp.
8  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
9  *              Michael C. Thompson <mcthomps@us.ibm.com>
10  *              Tyler Hicks <code@tyhicks.com>
11  */
12 
13 #include <linux/dcache.h>
14 #include <linux/file.h>
15 #include <linux/module.h>
16 #include <linux/namei.h>
17 #include <linux/skbuff.h>
18 #include <linux/mount.h>
19 #include <linux/pagemap.h>
20 #include <linux/key.h>
21 #include <linux/parser.h>
22 #include <linux/fs_stack.h>
23 #include <linux/slab.h>
24 #include <linux/magic.h>
25 #include "ecryptfs_kernel.h"
26 
27 /*
28  * Module parameter that defines the ecryptfs_verbosity level.
29  */
30 int ecryptfs_verbosity = 0;
31 
32 module_param(ecryptfs_verbosity, int, 0);
33 MODULE_PARM_DESC(ecryptfs_verbosity,
34 		 "Initial verbosity level (0 or 1; defaults to "
35 		 "0, which is Quiet)");
36 
37 /*
38  * Module parameter that defines the number of message buffer elements
39  */
40 unsigned int ecryptfs_message_buf_len = ECRYPTFS_DEFAULT_MSG_CTX_ELEMS;
41 
42 module_param(ecryptfs_message_buf_len, uint, 0);
43 MODULE_PARM_DESC(ecryptfs_message_buf_len,
44 		 "Number of message buffer elements");
45 
46 /*
47  * Module parameter that defines the maximum guaranteed amount of time to wait
48  * for a response from ecryptfsd.  The actual sleep time will be, more than
49  * likely, a small amount greater than this specified value, but only less if
50  * the message successfully arrives.
51  */
52 signed long ecryptfs_message_wait_timeout = ECRYPTFS_MAX_MSG_CTX_TTL / HZ;
53 
54 module_param(ecryptfs_message_wait_timeout, long, 0);
55 MODULE_PARM_DESC(ecryptfs_message_wait_timeout,
56 		 "Maximum number of seconds that an operation will "
57 		 "sleep while waiting for a message response from "
58 		 "userspace");
59 
60 /*
61  * Module parameter that is an estimate of the maximum number of users
62  * that will be concurrently using eCryptfs. Set this to the right
63  * value to balance performance and memory use.
64  */
65 unsigned int ecryptfs_number_of_users = ECRYPTFS_DEFAULT_NUM_USERS;
66 
67 module_param(ecryptfs_number_of_users, uint, 0);
68 MODULE_PARM_DESC(ecryptfs_number_of_users, "An estimate of the number of "
69 		 "concurrent users of eCryptfs");
70 
71 void __ecryptfs_printk(const char *fmt, ...)
72 {
73 	va_list args;
74 	va_start(args, fmt);
75 	if (fmt[1] == '7') { /* KERN_DEBUG */
76 		if (ecryptfs_verbosity >= 1)
77 			vprintk(fmt, args);
78 	} else
79 		vprintk(fmt, args);
80 	va_end(args);
81 }
82 
83 /*
84  * ecryptfs_init_lower_file
85  * @ecryptfs_dentry: Fully initialized eCryptfs dentry object, with
86  *                   the lower dentry and the lower mount set
87  *
88  * eCryptfs only ever keeps a single open file for every lower
89  * inode. All I/O operations to the lower inode occur through that
90  * file. When the first eCryptfs dentry that interposes with the first
91  * lower dentry for that inode is created, this function creates the
92  * lower file struct and associates it with the eCryptfs
93  * inode. When all eCryptfs files associated with the inode are released, the
94  * file is closed.
95  *
96  * The lower file will be opened with read/write permissions, if
97  * possible. Otherwise, it is opened read-only.
98  *
99  * This function does nothing if a lower file is already
100  * associated with the eCryptfs inode.
101  *
102  * Returns zero on success; non-zero otherwise
103  */
104 static int ecryptfs_init_lower_file(struct dentry *dentry,
105 				    struct file **lower_file)
106 {
107 	const struct cred *cred = current_cred();
108 	struct path *path = ecryptfs_dentry_to_lower_path(dentry);
109 	int rc;
110 
111 	rc = ecryptfs_privileged_open(lower_file, path->dentry, path->mnt,
112 				      cred);
113 	if (rc) {
114 		printk(KERN_ERR "Error opening lower file "
115 		       "for lower_dentry [0x%p] and lower_mnt [0x%p]; "
116 		       "rc = [%d]\n", path->dentry, path->mnt, rc);
117 		(*lower_file) = NULL;
118 	}
119 	return rc;
120 }
121 
122 int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode)
123 {
124 	struct ecryptfs_inode_info *inode_info;
125 	int count, rc = 0;
126 
127 	inode_info = ecryptfs_inode_to_private(inode);
128 	mutex_lock(&inode_info->lower_file_mutex);
129 	count = atomic_inc_return(&inode_info->lower_file_count);
130 	if (WARN_ON_ONCE(count < 1))
131 		rc = -EINVAL;
132 	else if (count == 1) {
133 		rc = ecryptfs_init_lower_file(dentry,
134 					      &inode_info->lower_file);
135 		if (rc)
136 			atomic_set(&inode_info->lower_file_count, 0);
137 	}
138 	mutex_unlock(&inode_info->lower_file_mutex);
139 	return rc;
140 }
141 
142 void ecryptfs_put_lower_file(struct inode *inode)
143 {
144 	struct ecryptfs_inode_info *inode_info;
145 
146 	inode_info = ecryptfs_inode_to_private(inode);
147 	if (atomic_dec_and_mutex_lock(&inode_info->lower_file_count,
148 				      &inode_info->lower_file_mutex)) {
149 		filemap_write_and_wait(inode->i_mapping);
150 		fput(inode_info->lower_file);
151 		inode_info->lower_file = NULL;
152 		mutex_unlock(&inode_info->lower_file_mutex);
153 	}
154 }
155 
156 enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig,
157        ecryptfs_opt_cipher, ecryptfs_opt_ecryptfs_cipher,
158        ecryptfs_opt_ecryptfs_key_bytes,
159        ecryptfs_opt_passthrough, ecryptfs_opt_xattr_metadata,
160        ecryptfs_opt_encrypted_view, ecryptfs_opt_fnek_sig,
161        ecryptfs_opt_fn_cipher, ecryptfs_opt_fn_cipher_key_bytes,
162        ecryptfs_opt_unlink_sigs, ecryptfs_opt_mount_auth_tok_only,
163        ecryptfs_opt_check_dev_ruid,
164        ecryptfs_opt_err };
165 
166 static const match_table_t tokens = {
167 	{ecryptfs_opt_sig, "sig=%s"},
168 	{ecryptfs_opt_ecryptfs_sig, "ecryptfs_sig=%s"},
169 	{ecryptfs_opt_cipher, "cipher=%s"},
170 	{ecryptfs_opt_ecryptfs_cipher, "ecryptfs_cipher=%s"},
171 	{ecryptfs_opt_ecryptfs_key_bytes, "ecryptfs_key_bytes=%u"},
172 	{ecryptfs_opt_passthrough, "ecryptfs_passthrough"},
173 	{ecryptfs_opt_xattr_metadata, "ecryptfs_xattr_metadata"},
174 	{ecryptfs_opt_encrypted_view, "ecryptfs_encrypted_view"},
175 	{ecryptfs_opt_fnek_sig, "ecryptfs_fnek_sig=%s"},
176 	{ecryptfs_opt_fn_cipher, "ecryptfs_fn_cipher=%s"},
177 	{ecryptfs_opt_fn_cipher_key_bytes, "ecryptfs_fn_key_bytes=%u"},
178 	{ecryptfs_opt_unlink_sigs, "ecryptfs_unlink_sigs"},
179 	{ecryptfs_opt_mount_auth_tok_only, "ecryptfs_mount_auth_tok_only"},
180 	{ecryptfs_opt_check_dev_ruid, "ecryptfs_check_dev_ruid"},
181 	{ecryptfs_opt_err, NULL}
182 };
183 
184 static int ecryptfs_init_global_auth_toks(
185 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
186 {
187 	struct ecryptfs_global_auth_tok *global_auth_tok;
188 	struct ecryptfs_auth_tok *auth_tok;
189 	int rc = 0;
190 
191 	list_for_each_entry(global_auth_tok,
192 			    &mount_crypt_stat->global_auth_tok_list,
193 			    mount_crypt_stat_list) {
194 		rc = ecryptfs_keyring_auth_tok_for_sig(
195 			&global_auth_tok->global_auth_tok_key, &auth_tok,
196 			global_auth_tok->sig);
197 		if (rc) {
198 			printk(KERN_ERR "Could not find valid key in user "
199 			       "session keyring for sig specified in mount "
200 			       "option: [%s]\n", global_auth_tok->sig);
201 			global_auth_tok->flags |= ECRYPTFS_AUTH_TOK_INVALID;
202 			goto out;
203 		} else {
204 			global_auth_tok->flags &= ~ECRYPTFS_AUTH_TOK_INVALID;
205 			up_write(&(global_auth_tok->global_auth_tok_key)->sem);
206 		}
207 	}
208 out:
209 	return rc;
210 }
211 
212 static void ecryptfs_init_mount_crypt_stat(
213 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
214 {
215 	memset((void *)mount_crypt_stat, 0,
216 	       sizeof(struct ecryptfs_mount_crypt_stat));
217 	INIT_LIST_HEAD(&mount_crypt_stat->global_auth_tok_list);
218 	mutex_init(&mount_crypt_stat->global_auth_tok_list_mutex);
219 	mount_crypt_stat->flags |= ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED;
220 }
221 
222 /**
223  * ecryptfs_parse_options
224  * @sbi: The ecryptfs super block
225  * @options: The options passed to the kernel
226  * @check_ruid: set to 1 if device uid should be checked against the ruid
227  *
228  * Parse mount options:
229  * debug=N 	   - ecryptfs_verbosity level for debug output
230  * sig=XXX	   - description(signature) of the key to use
231  *
232  * Returns the dentry object of the lower-level (lower/interposed)
233  * directory; We want to mount our stackable file system on top of
234  * that lower directory.
235  *
236  * The signature of the key to use must be the description of a key
237  * already in the keyring. Mounting will fail if the key can not be
238  * found.
239  *
240  * Returns zero on success; non-zero on error
241  */
242 static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
243 				  uid_t *check_ruid)
244 {
245 	char *p;
246 	int rc = 0;
247 	int sig_set = 0;
248 	int cipher_name_set = 0;
249 	int fn_cipher_name_set = 0;
250 	int cipher_key_bytes;
251 	int cipher_key_bytes_set = 0;
252 	int fn_cipher_key_bytes;
253 	int fn_cipher_key_bytes_set = 0;
254 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
255 		&sbi->mount_crypt_stat;
256 	substring_t args[MAX_OPT_ARGS];
257 	int token;
258 	char *sig_src;
259 	char *cipher_name_dst;
260 	char *cipher_name_src;
261 	char *fn_cipher_name_dst;
262 	char *fn_cipher_name_src;
263 	char *fnek_dst;
264 	char *fnek_src;
265 	char *cipher_key_bytes_src;
266 	char *fn_cipher_key_bytes_src;
267 	u8 cipher_code;
268 
269 	*check_ruid = 0;
270 
271 	if (!options) {
272 		rc = -EINVAL;
273 		goto out;
274 	}
275 	ecryptfs_init_mount_crypt_stat(mount_crypt_stat);
276 	while ((p = strsep(&options, ",")) != NULL) {
277 		if (!*p)
278 			continue;
279 		token = match_token(p, tokens, args);
280 		switch (token) {
281 		case ecryptfs_opt_sig:
282 		case ecryptfs_opt_ecryptfs_sig:
283 			sig_src = args[0].from;
284 			rc = ecryptfs_add_global_auth_tok(mount_crypt_stat,
285 							  sig_src, 0);
286 			if (rc) {
287 				printk(KERN_ERR "Error attempting to register "
288 				       "global sig; rc = [%d]\n", rc);
289 				goto out;
290 			}
291 			sig_set = 1;
292 			break;
293 		case ecryptfs_opt_cipher:
294 		case ecryptfs_opt_ecryptfs_cipher:
295 			cipher_name_src = args[0].from;
296 			cipher_name_dst =
297 				mount_crypt_stat->
298 				global_default_cipher_name;
299 			strncpy(cipher_name_dst, cipher_name_src,
300 				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
301 			cipher_name_dst[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
302 			cipher_name_set = 1;
303 			break;
304 		case ecryptfs_opt_ecryptfs_key_bytes:
305 			cipher_key_bytes_src = args[0].from;
306 			cipher_key_bytes =
307 				(int)simple_strtol(cipher_key_bytes_src,
308 						   &cipher_key_bytes_src, 0);
309 			mount_crypt_stat->global_default_cipher_key_size =
310 				cipher_key_bytes;
311 			cipher_key_bytes_set = 1;
312 			break;
313 		case ecryptfs_opt_passthrough:
314 			mount_crypt_stat->flags |=
315 				ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED;
316 			break;
317 		case ecryptfs_opt_xattr_metadata:
318 			mount_crypt_stat->flags |=
319 				ECRYPTFS_XATTR_METADATA_ENABLED;
320 			break;
321 		case ecryptfs_opt_encrypted_view:
322 			mount_crypt_stat->flags |=
323 				ECRYPTFS_XATTR_METADATA_ENABLED;
324 			mount_crypt_stat->flags |=
325 				ECRYPTFS_ENCRYPTED_VIEW_ENABLED;
326 			break;
327 		case ecryptfs_opt_fnek_sig:
328 			fnek_src = args[0].from;
329 			fnek_dst =
330 				mount_crypt_stat->global_default_fnek_sig;
331 			strncpy(fnek_dst, fnek_src, ECRYPTFS_SIG_SIZE_HEX);
332 			mount_crypt_stat->global_default_fnek_sig[
333 				ECRYPTFS_SIG_SIZE_HEX] = '\0';
334 			rc = ecryptfs_add_global_auth_tok(
335 				mount_crypt_stat,
336 				mount_crypt_stat->global_default_fnek_sig,
337 				ECRYPTFS_AUTH_TOK_FNEK);
338 			if (rc) {
339 				printk(KERN_ERR "Error attempting to register "
340 				       "global fnek sig [%s]; rc = [%d]\n",
341 				       mount_crypt_stat->global_default_fnek_sig,
342 				       rc);
343 				goto out;
344 			}
345 			mount_crypt_stat->flags |=
346 				(ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES
347 				 | ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK);
348 			break;
349 		case ecryptfs_opt_fn_cipher:
350 			fn_cipher_name_src = args[0].from;
351 			fn_cipher_name_dst =
352 				mount_crypt_stat->global_default_fn_cipher_name;
353 			strncpy(fn_cipher_name_dst, fn_cipher_name_src,
354 				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
355 			mount_crypt_stat->global_default_fn_cipher_name[
356 				ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
357 			fn_cipher_name_set = 1;
358 			break;
359 		case ecryptfs_opt_fn_cipher_key_bytes:
360 			fn_cipher_key_bytes_src = args[0].from;
361 			fn_cipher_key_bytes =
362 				(int)simple_strtol(fn_cipher_key_bytes_src,
363 						   &fn_cipher_key_bytes_src, 0);
364 			mount_crypt_stat->global_default_fn_cipher_key_bytes =
365 				fn_cipher_key_bytes;
366 			fn_cipher_key_bytes_set = 1;
367 			break;
368 		case ecryptfs_opt_unlink_sigs:
369 			mount_crypt_stat->flags |= ECRYPTFS_UNLINK_SIGS;
370 			break;
371 		case ecryptfs_opt_mount_auth_tok_only:
372 			mount_crypt_stat->flags |=
373 				ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY;
374 			break;
375 		case ecryptfs_opt_check_dev_ruid:
376 			*check_ruid = 1;
377 			break;
378 		case ecryptfs_opt_err:
379 		default:
380 			printk(KERN_WARNING
381 			       "%s: eCryptfs: unrecognized option [%s]\n",
382 			       __func__, p);
383 		}
384 	}
385 	if (!sig_set) {
386 		rc = -EINVAL;
387 		ecryptfs_printk(KERN_ERR, "You must supply at least one valid "
388 				"auth tok signature as a mount "
389 				"parameter; see the eCryptfs README\n");
390 		goto out;
391 	}
392 	if (!cipher_name_set) {
393 		int cipher_name_len = strlen(ECRYPTFS_DEFAULT_CIPHER);
394 
395 		BUG_ON(cipher_name_len > ECRYPTFS_MAX_CIPHER_NAME_SIZE);
396 		strcpy(mount_crypt_stat->global_default_cipher_name,
397 		       ECRYPTFS_DEFAULT_CIPHER);
398 	}
399 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
400 	    && !fn_cipher_name_set)
401 		strcpy(mount_crypt_stat->global_default_fn_cipher_name,
402 		       mount_crypt_stat->global_default_cipher_name);
403 	if (!cipher_key_bytes_set)
404 		mount_crypt_stat->global_default_cipher_key_size = 0;
405 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
406 	    && !fn_cipher_key_bytes_set)
407 		mount_crypt_stat->global_default_fn_cipher_key_bytes =
408 			mount_crypt_stat->global_default_cipher_key_size;
409 
410 	cipher_code = ecryptfs_code_for_cipher_string(
411 		mount_crypt_stat->global_default_cipher_name,
412 		mount_crypt_stat->global_default_cipher_key_size);
413 	if (!cipher_code) {
414 		ecryptfs_printk(KERN_ERR,
415 				"eCryptfs doesn't support cipher: %s\n",
416 				mount_crypt_stat->global_default_cipher_name);
417 		rc = -EINVAL;
418 		goto out;
419 	}
420 
421 	mutex_lock(&key_tfm_list_mutex);
422 	if (!ecryptfs_tfm_exists(mount_crypt_stat->global_default_cipher_name,
423 				 NULL)) {
424 		rc = ecryptfs_add_new_key_tfm(
425 			NULL, mount_crypt_stat->global_default_cipher_name,
426 			mount_crypt_stat->global_default_cipher_key_size);
427 		if (rc) {
428 			printk(KERN_ERR "Error attempting to initialize "
429 			       "cipher with name = [%s] and key size = [%td]; "
430 			       "rc = [%d]\n",
431 			       mount_crypt_stat->global_default_cipher_name,
432 			       mount_crypt_stat->global_default_cipher_key_size,
433 			       rc);
434 			rc = -EINVAL;
435 			mutex_unlock(&key_tfm_list_mutex);
436 			goto out;
437 		}
438 	}
439 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
440 	    && !ecryptfs_tfm_exists(
441 		    mount_crypt_stat->global_default_fn_cipher_name, NULL)) {
442 		rc = ecryptfs_add_new_key_tfm(
443 			NULL, mount_crypt_stat->global_default_fn_cipher_name,
444 			mount_crypt_stat->global_default_fn_cipher_key_bytes);
445 		if (rc) {
446 			printk(KERN_ERR "Error attempting to initialize "
447 			       "cipher with name = [%s] and key size = [%td]; "
448 			       "rc = [%d]\n",
449 			       mount_crypt_stat->global_default_fn_cipher_name,
450 			       mount_crypt_stat->global_default_fn_cipher_key_bytes,
451 			       rc);
452 			rc = -EINVAL;
453 			mutex_unlock(&key_tfm_list_mutex);
454 			goto out;
455 		}
456 	}
457 	mutex_unlock(&key_tfm_list_mutex);
458 	rc = ecryptfs_init_global_auth_toks(mount_crypt_stat);
459 	if (rc)
460 		printk(KERN_WARNING "One or more global auth toks could not "
461 		       "properly register; rc = [%d]\n", rc);
462 out:
463 	return rc;
464 }
465 
466 struct kmem_cache *ecryptfs_sb_info_cache;
467 static struct file_system_type ecryptfs_fs_type;
468 
469 /*
470  * ecryptfs_mount
471  * @fs_type: The filesystem type that the superblock should belong to
472  * @flags: The flags associated with the mount
473  * @dev_name: The path to mount over
474  * @raw_data: The options passed into the kernel
475  */
476 static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags,
477 			const char *dev_name, void *raw_data)
478 {
479 	struct super_block *s;
480 	struct ecryptfs_sb_info *sbi;
481 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
482 	struct ecryptfs_dentry_info *root_info;
483 	const char *err = "Getting sb failed";
484 	struct inode *inode;
485 	struct path path;
486 	uid_t check_ruid;
487 	int rc;
488 
489 	sbi = kmem_cache_zalloc(ecryptfs_sb_info_cache, GFP_KERNEL);
490 	if (!sbi) {
491 		rc = -ENOMEM;
492 		goto out;
493 	}
494 
495 	if (!dev_name) {
496 		rc = -EINVAL;
497 		err = "Device name cannot be null";
498 		goto out;
499 	}
500 
501 	rc = ecryptfs_parse_options(sbi, raw_data, &check_ruid);
502 	if (rc) {
503 		err = "Error parsing options";
504 		goto out;
505 	}
506 	mount_crypt_stat = &sbi->mount_crypt_stat;
507 
508 	s = sget(fs_type, NULL, set_anon_super, flags, NULL);
509 	if (IS_ERR(s)) {
510 		rc = PTR_ERR(s);
511 		goto out;
512 	}
513 
514 	rc = super_setup_bdi(s);
515 	if (rc)
516 		goto out1;
517 
518 	ecryptfs_set_superblock_private(s, sbi);
519 
520 	/* ->kill_sb() will take care of sbi after that point */
521 	sbi = NULL;
522 	s->s_op = &ecryptfs_sops;
523 	s->s_xattr = ecryptfs_xattr_handlers;
524 	s->s_d_op = &ecryptfs_dops;
525 
526 	err = "Reading sb failed";
527 	rc = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
528 	if (rc) {
529 		ecryptfs_printk(KERN_WARNING, "kern_path() failed\n");
530 		goto out1;
531 	}
532 	if (path.dentry->d_sb->s_type == &ecryptfs_fs_type) {
533 		rc = -EINVAL;
534 		printk(KERN_ERR "Mount on filesystem of type "
535 			"eCryptfs explicitly disallowed due to "
536 			"known incompatibilities\n");
537 		goto out_free;
538 	}
539 
540 	if (mnt_user_ns(path.mnt) != &init_user_ns) {
541 		rc = -EINVAL;
542 		printk(KERN_ERR "Mounting on idmapped mounts currently disallowed\n");
543 		goto out_free;
544 	}
545 
546 	if (check_ruid && !uid_eq(d_inode(path.dentry)->i_uid, current_uid())) {
547 		rc = -EPERM;
548 		printk(KERN_ERR "Mount of device (uid: %d) not owned by "
549 		       "requested user (uid: %d)\n",
550 			i_uid_read(d_inode(path.dentry)),
551 			from_kuid(&init_user_ns, current_uid()));
552 		goto out_free;
553 	}
554 
555 	ecryptfs_set_superblock_lower(s, path.dentry->d_sb);
556 
557 	/**
558 	 * Set the POSIX ACL flag based on whether they're enabled in the lower
559 	 * mount.
560 	 */
561 	s->s_flags = flags & ~SB_POSIXACL;
562 	s->s_flags |= path.dentry->d_sb->s_flags & SB_POSIXACL;
563 
564 	/**
565 	 * Force a read-only eCryptfs mount when:
566 	 *   1) The lower mount is ro
567 	 *   2) The ecryptfs_encrypted_view mount option is specified
568 	 */
569 	if (sb_rdonly(path.dentry->d_sb) || mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
570 		s->s_flags |= SB_RDONLY;
571 
572 	s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
573 	s->s_blocksize = path.dentry->d_sb->s_blocksize;
574 	s->s_magic = ECRYPTFS_SUPER_MAGIC;
575 	s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1;
576 
577 	rc = -EINVAL;
578 	if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
579 		pr_err("eCryptfs: maximum fs stacking depth exceeded\n");
580 		goto out_free;
581 	}
582 
583 	inode = ecryptfs_get_inode(d_inode(path.dentry), s);
584 	rc = PTR_ERR(inode);
585 	if (IS_ERR(inode))
586 		goto out_free;
587 
588 	s->s_root = d_make_root(inode);
589 	if (!s->s_root) {
590 		rc = -ENOMEM;
591 		goto out_free;
592 	}
593 
594 	rc = -ENOMEM;
595 	root_info = kmem_cache_zalloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
596 	if (!root_info)
597 		goto out_free;
598 
599 	/* ->kill_sb() will take care of root_info */
600 	ecryptfs_set_dentry_private(s->s_root, root_info);
601 	root_info->lower_path = path;
602 
603 	s->s_flags |= SB_ACTIVE;
604 	return dget(s->s_root);
605 
606 out_free:
607 	path_put(&path);
608 out1:
609 	deactivate_locked_super(s);
610 out:
611 	if (sbi) {
612 		ecryptfs_destroy_mount_crypt_stat(&sbi->mount_crypt_stat);
613 		kmem_cache_free(ecryptfs_sb_info_cache, sbi);
614 	}
615 	printk(KERN_ERR "%s; rc = [%d]\n", err, rc);
616 	return ERR_PTR(rc);
617 }
618 
619 /**
620  * ecryptfs_kill_block_super
621  * @sb: The ecryptfs super block
622  *
623  * Used to bring the superblock down and free the private data.
624  */
625 static void ecryptfs_kill_block_super(struct super_block *sb)
626 {
627 	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
628 	kill_anon_super(sb);
629 	if (!sb_info)
630 		return;
631 	ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
632 	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
633 }
634 
635 static struct file_system_type ecryptfs_fs_type = {
636 	.owner = THIS_MODULE,
637 	.name = "ecryptfs",
638 	.mount = ecryptfs_mount,
639 	.kill_sb = ecryptfs_kill_block_super,
640 	.fs_flags = 0
641 };
642 MODULE_ALIAS_FS("ecryptfs");
643 
644 /*
645  * inode_info_init_once
646  *
647  * Initializes the ecryptfs_inode_info_cache when it is created
648  */
649 static void
650 inode_info_init_once(void *vptr)
651 {
652 	struct ecryptfs_inode_info *ei = (struct ecryptfs_inode_info *)vptr;
653 
654 	inode_init_once(&ei->vfs_inode);
655 }
656 
657 static struct ecryptfs_cache_info {
658 	struct kmem_cache **cache;
659 	const char *name;
660 	size_t size;
661 	slab_flags_t flags;
662 	void (*ctor)(void *obj);
663 } ecryptfs_cache_infos[] = {
664 	{
665 		.cache = &ecryptfs_auth_tok_list_item_cache,
666 		.name = "ecryptfs_auth_tok_list_item",
667 		.size = sizeof(struct ecryptfs_auth_tok_list_item),
668 	},
669 	{
670 		.cache = &ecryptfs_file_info_cache,
671 		.name = "ecryptfs_file_cache",
672 		.size = sizeof(struct ecryptfs_file_info),
673 	},
674 	{
675 		.cache = &ecryptfs_dentry_info_cache,
676 		.name = "ecryptfs_dentry_info_cache",
677 		.size = sizeof(struct ecryptfs_dentry_info),
678 	},
679 	{
680 		.cache = &ecryptfs_inode_info_cache,
681 		.name = "ecryptfs_inode_cache",
682 		.size = sizeof(struct ecryptfs_inode_info),
683 		.flags = SLAB_ACCOUNT,
684 		.ctor = inode_info_init_once,
685 	},
686 	{
687 		.cache = &ecryptfs_sb_info_cache,
688 		.name = "ecryptfs_sb_cache",
689 		.size = sizeof(struct ecryptfs_sb_info),
690 	},
691 	{
692 		.cache = &ecryptfs_header_cache,
693 		.name = "ecryptfs_headers",
694 		.size = PAGE_SIZE,
695 	},
696 	{
697 		.cache = &ecryptfs_xattr_cache,
698 		.name = "ecryptfs_xattr_cache",
699 		.size = PAGE_SIZE,
700 	},
701 	{
702 		.cache = &ecryptfs_key_record_cache,
703 		.name = "ecryptfs_key_record_cache",
704 		.size = sizeof(struct ecryptfs_key_record),
705 	},
706 	{
707 		.cache = &ecryptfs_key_sig_cache,
708 		.name = "ecryptfs_key_sig_cache",
709 		.size = sizeof(struct ecryptfs_key_sig),
710 	},
711 	{
712 		.cache = &ecryptfs_global_auth_tok_cache,
713 		.name = "ecryptfs_global_auth_tok_cache",
714 		.size = sizeof(struct ecryptfs_global_auth_tok),
715 	},
716 	{
717 		.cache = &ecryptfs_key_tfm_cache,
718 		.name = "ecryptfs_key_tfm_cache",
719 		.size = sizeof(struct ecryptfs_key_tfm),
720 	},
721 };
722 
723 static void ecryptfs_free_kmem_caches(void)
724 {
725 	int i;
726 
727 	/*
728 	 * Make sure all delayed rcu free inodes are flushed before we
729 	 * destroy cache.
730 	 */
731 	rcu_barrier();
732 
733 	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
734 		struct ecryptfs_cache_info *info;
735 
736 		info = &ecryptfs_cache_infos[i];
737 		kmem_cache_destroy(*(info->cache));
738 	}
739 }
740 
741 /**
742  * ecryptfs_init_kmem_caches
743  *
744  * Returns zero on success; non-zero otherwise
745  */
746 static int ecryptfs_init_kmem_caches(void)
747 {
748 	int i;
749 
750 	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
751 		struct ecryptfs_cache_info *info;
752 
753 		info = &ecryptfs_cache_infos[i];
754 		*(info->cache) = kmem_cache_create(info->name, info->size, 0,
755 				SLAB_HWCACHE_ALIGN | info->flags, info->ctor);
756 		if (!*(info->cache)) {
757 			ecryptfs_free_kmem_caches();
758 			ecryptfs_printk(KERN_WARNING, "%s: "
759 					"kmem_cache_create failed\n",
760 					info->name);
761 			return -ENOMEM;
762 		}
763 	}
764 	return 0;
765 }
766 
767 static struct kobject *ecryptfs_kobj;
768 
769 static ssize_t version_show(struct kobject *kobj,
770 			    struct kobj_attribute *attr, char *buff)
771 {
772 	return snprintf(buff, PAGE_SIZE, "%d\n", ECRYPTFS_VERSIONING_MASK);
773 }
774 
775 static struct kobj_attribute version_attr = __ATTR_RO(version);
776 
777 static struct attribute *attributes[] = {
778 	&version_attr.attr,
779 	NULL,
780 };
781 
782 static const struct attribute_group attr_group = {
783 	.attrs = attributes,
784 };
785 
786 static int do_sysfs_registration(void)
787 {
788 	int rc;
789 
790 	ecryptfs_kobj = kobject_create_and_add("ecryptfs", fs_kobj);
791 	if (!ecryptfs_kobj) {
792 		printk(KERN_ERR "Unable to create ecryptfs kset\n");
793 		rc = -ENOMEM;
794 		goto out;
795 	}
796 	rc = sysfs_create_group(ecryptfs_kobj, &attr_group);
797 	if (rc) {
798 		printk(KERN_ERR
799 		       "Unable to create ecryptfs version attributes\n");
800 		kobject_put(ecryptfs_kobj);
801 	}
802 out:
803 	return rc;
804 }
805 
806 static void do_sysfs_unregistration(void)
807 {
808 	sysfs_remove_group(ecryptfs_kobj, &attr_group);
809 	kobject_put(ecryptfs_kobj);
810 }
811 
812 static int __init ecryptfs_init(void)
813 {
814 	int rc;
815 
816 	if (ECRYPTFS_DEFAULT_EXTENT_SIZE > PAGE_SIZE) {
817 		rc = -EINVAL;
818 		ecryptfs_printk(KERN_ERR, "The eCryptfs extent size is "
819 				"larger than the host's page size, and so "
820 				"eCryptfs cannot run on this system. The "
821 				"default eCryptfs extent size is [%u] bytes; "
822 				"the page size is [%lu] bytes.\n",
823 				ECRYPTFS_DEFAULT_EXTENT_SIZE,
824 				(unsigned long)PAGE_SIZE);
825 		goto out;
826 	}
827 	rc = ecryptfs_init_kmem_caches();
828 	if (rc) {
829 		printk(KERN_ERR
830 		       "Failed to allocate one or more kmem_cache objects\n");
831 		goto out;
832 	}
833 	rc = do_sysfs_registration();
834 	if (rc) {
835 		printk(KERN_ERR "sysfs registration failed\n");
836 		goto out_free_kmem_caches;
837 	}
838 	rc = ecryptfs_init_kthread();
839 	if (rc) {
840 		printk(KERN_ERR "%s: kthread initialization failed; "
841 		       "rc = [%d]\n", __func__, rc);
842 		goto out_do_sysfs_unregistration;
843 	}
844 	rc = ecryptfs_init_messaging();
845 	if (rc) {
846 		printk(KERN_ERR "Failure occurred while attempting to "
847 				"initialize the communications channel to "
848 				"ecryptfsd\n");
849 		goto out_destroy_kthread;
850 	}
851 	rc = ecryptfs_init_crypto();
852 	if (rc) {
853 		printk(KERN_ERR "Failure whilst attempting to init crypto; "
854 		       "rc = [%d]\n", rc);
855 		goto out_release_messaging;
856 	}
857 	rc = register_filesystem(&ecryptfs_fs_type);
858 	if (rc) {
859 		printk(KERN_ERR "Failed to register filesystem\n");
860 		goto out_destroy_crypto;
861 	}
862 	if (ecryptfs_verbosity > 0)
863 		printk(KERN_CRIT "eCryptfs verbosity set to %d. Secret values "
864 			"will be written to the syslog!\n", ecryptfs_verbosity);
865 
866 	goto out;
867 out_destroy_crypto:
868 	ecryptfs_destroy_crypto();
869 out_release_messaging:
870 	ecryptfs_release_messaging();
871 out_destroy_kthread:
872 	ecryptfs_destroy_kthread();
873 out_do_sysfs_unregistration:
874 	do_sysfs_unregistration();
875 out_free_kmem_caches:
876 	ecryptfs_free_kmem_caches();
877 out:
878 	return rc;
879 }
880 
881 static void __exit ecryptfs_exit(void)
882 {
883 	int rc;
884 
885 	rc = ecryptfs_destroy_crypto();
886 	if (rc)
887 		printk(KERN_ERR "Failure whilst attempting to destroy crypto; "
888 		       "rc = [%d]\n", rc);
889 	ecryptfs_release_messaging();
890 	ecryptfs_destroy_kthread();
891 	do_sysfs_unregistration();
892 	unregister_filesystem(&ecryptfs_fs_type);
893 	ecryptfs_free_kmem_caches();
894 }
895 
896 MODULE_AUTHOR("Michael A. Halcrow <mhalcrow@us.ibm.com>");
897 MODULE_DESCRIPTION("eCryptfs");
898 
899 MODULE_LICENSE("GPL");
900 
901 module_init(ecryptfs_init)
902 module_exit(ecryptfs_exit)
903