1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 1997-2004 Erez Zadok
6 * Copyright (C) 2001-2004 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 */
11
12 #include <crypto/hash.h>
13 #include <crypto/skcipher.h>
14 #include <linux/fs.h>
15 #include <linux/mount.h>
16 #include <linux/pagemap.h>
17 #include <linux/random.h>
18 #include <linux/compiler.h>
19 #include <linux/key.h>
20 #include <linux/namei.h>
21 #include <linux/file.h>
22 #include <linux/scatterlist.h>
23 #include <linux/slab.h>
24 #include <asm/unaligned.h>
25 #include <linux/kernel.h>
26 #include <linux/xattr.h>
27 #include "ecryptfs_kernel.h"
28
29 #define DECRYPT 0
30 #define ENCRYPT 1
31
32 /**
33 * ecryptfs_from_hex
34 * @dst: Buffer to take the bytes from src hex; must be at least of
35 * size (src_size / 2)
36 * @src: Buffer to be converted from a hex string representation to raw value
37 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
38 */
ecryptfs_from_hex(char * dst,char * src,int dst_size)39 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
40 {
41 int x;
42 char tmp[3] = { 0, };
43
44 for (x = 0; x < dst_size; x++) {
45 tmp[0] = src[x * 2];
46 tmp[1] = src[x * 2 + 1];
47 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
48 }
49 }
50
51 /**
52 * ecryptfs_calculate_md5 - calculates the md5 of @src
53 * @dst: Pointer to 16 bytes of allocated memory
54 * @crypt_stat: Pointer to crypt_stat struct for the current inode
55 * @src: Data to be md5'd
56 * @len: Length of @src
57 *
58 * Uses the allocated crypto context that crypt_stat references to
59 * generate the MD5 sum of the contents of src.
60 */
ecryptfs_calculate_md5(char * dst,struct ecryptfs_crypt_stat * crypt_stat,char * src,int len)61 static int ecryptfs_calculate_md5(char *dst,
62 struct ecryptfs_crypt_stat *crypt_stat,
63 char *src, int len)
64 {
65 int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst);
66
67 if (rc) {
68 printk(KERN_ERR
69 "%s: Error computing crypto hash; rc = [%d]\n",
70 __func__, rc);
71 goto out;
72 }
73 out:
74 return rc;
75 }
76
ecryptfs_crypto_api_algify_cipher_name(char ** algified_name,char * cipher_name,char * chaining_modifier)77 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
78 char *cipher_name,
79 char *chaining_modifier)
80 {
81 int cipher_name_len = strlen(cipher_name);
82 int chaining_modifier_len = strlen(chaining_modifier);
83 int algified_name_len;
84 int rc;
85
86 algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
87 (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
88 if (!(*algified_name)) {
89 rc = -ENOMEM;
90 goto out;
91 }
92 snprintf((*algified_name), algified_name_len, "%s(%s)",
93 chaining_modifier, cipher_name);
94 rc = 0;
95 out:
96 return rc;
97 }
98
99 /**
100 * ecryptfs_derive_iv
101 * @iv: destination for the derived iv vale
102 * @crypt_stat: Pointer to crypt_stat struct for the current inode
103 * @offset: Offset of the extent whose IV we are to derive
104 *
105 * Generate the initialization vector from the given root IV and page
106 * offset.
107 *
108 * Returns zero on success; non-zero on error.
109 */
ecryptfs_derive_iv(char * iv,struct ecryptfs_crypt_stat * crypt_stat,loff_t offset)110 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
111 loff_t offset)
112 {
113 int rc = 0;
114 char dst[MD5_DIGEST_SIZE];
115 char src[ECRYPTFS_MAX_IV_BYTES + 16];
116
117 if (unlikely(ecryptfs_verbosity > 0)) {
118 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
119 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
120 }
121 /* TODO: It is probably secure to just cast the least
122 * significant bits of the root IV into an unsigned long and
123 * add the offset to that rather than go through all this
124 * hashing business. -Halcrow */
125 memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
126 memset((src + crypt_stat->iv_bytes), 0, 16);
127 snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
128 if (unlikely(ecryptfs_verbosity > 0)) {
129 ecryptfs_printk(KERN_DEBUG, "source:\n");
130 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
131 }
132 rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
133 (crypt_stat->iv_bytes + 16));
134 if (rc) {
135 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
136 "MD5 while generating IV for a page\n");
137 goto out;
138 }
139 memcpy(iv, dst, crypt_stat->iv_bytes);
140 if (unlikely(ecryptfs_verbosity > 0)) {
141 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
142 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
143 }
144 out:
145 return rc;
146 }
147
148 /**
149 * ecryptfs_init_crypt_stat
150 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
151 *
152 * Initialize the crypt_stat structure.
153 */
ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat * crypt_stat)154 int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
155 {
156 struct crypto_shash *tfm;
157 int rc;
158
159 tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
160 if (IS_ERR(tfm)) {
161 rc = PTR_ERR(tfm);
162 ecryptfs_printk(KERN_ERR, "Error attempting to "
163 "allocate crypto context; rc = [%d]\n",
164 rc);
165 return rc;
166 }
167
168 memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
169 INIT_LIST_HEAD(&crypt_stat->keysig_list);
170 mutex_init(&crypt_stat->keysig_list_mutex);
171 mutex_init(&crypt_stat->cs_mutex);
172 mutex_init(&crypt_stat->cs_tfm_mutex);
173 crypt_stat->hash_tfm = tfm;
174 crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
175
176 return 0;
177 }
178
179 /**
180 * ecryptfs_destroy_crypt_stat
181 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
182 *
183 * Releases all memory associated with a crypt_stat struct.
184 */
ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat * crypt_stat)185 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
186 {
187 struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
188
189 crypto_free_skcipher(crypt_stat->tfm);
190 crypto_free_shash(crypt_stat->hash_tfm);
191 list_for_each_entry_safe(key_sig, key_sig_tmp,
192 &crypt_stat->keysig_list, crypt_stat_list) {
193 list_del(&key_sig->crypt_stat_list);
194 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
195 }
196 memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
197 }
198
ecryptfs_destroy_mount_crypt_stat(struct ecryptfs_mount_crypt_stat * mount_crypt_stat)199 void ecryptfs_destroy_mount_crypt_stat(
200 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
201 {
202 struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
203
204 if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
205 return;
206 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
207 list_for_each_entry_safe(auth_tok, auth_tok_tmp,
208 &mount_crypt_stat->global_auth_tok_list,
209 mount_crypt_stat_list) {
210 list_del(&auth_tok->mount_crypt_stat_list);
211 if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
212 key_put(auth_tok->global_auth_tok_key);
213 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
214 }
215 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
216 memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
217 }
218
219 /**
220 * virt_to_scatterlist
221 * @addr: Virtual address
222 * @size: Size of data; should be an even multiple of the block size
223 * @sg: Pointer to scatterlist array; set to NULL to obtain only
224 * the number of scatterlist structs required in array
225 * @sg_size: Max array size
226 *
227 * Fills in a scatterlist array with page references for a passed
228 * virtual address.
229 *
230 * Returns the number of scatterlist structs in array used
231 */
virt_to_scatterlist(const void * addr,int size,struct scatterlist * sg,int sg_size)232 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
233 int sg_size)
234 {
235 int i = 0;
236 struct page *pg;
237 int offset;
238 int remainder_of_page;
239
240 sg_init_table(sg, sg_size);
241
242 while (size > 0 && i < sg_size) {
243 pg = virt_to_page(addr);
244 offset = offset_in_page(addr);
245 sg_set_page(&sg[i], pg, 0, offset);
246 remainder_of_page = PAGE_SIZE - offset;
247 if (size >= remainder_of_page) {
248 sg[i].length = remainder_of_page;
249 addr += remainder_of_page;
250 size -= remainder_of_page;
251 } else {
252 sg[i].length = size;
253 addr += size;
254 size = 0;
255 }
256 i++;
257 }
258 if (size > 0)
259 return -ENOMEM;
260 return i;
261 }
262
263 struct extent_crypt_result {
264 struct completion completion;
265 int rc;
266 };
267
extent_crypt_complete(struct crypto_async_request * req,int rc)268 static void extent_crypt_complete(struct crypto_async_request *req, int rc)
269 {
270 struct extent_crypt_result *ecr = req->data;
271
272 if (rc == -EINPROGRESS)
273 return;
274
275 ecr->rc = rc;
276 complete(&ecr->completion);
277 }
278
279 /**
280 * crypt_scatterlist
281 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
282 * @dst_sg: Destination of the data after performing the crypto operation
283 * @src_sg: Data to be encrypted or decrypted
284 * @size: Length of data
285 * @iv: IV to use
286 * @op: ENCRYPT or DECRYPT to indicate the desired operation
287 *
288 * Returns the number of bytes encrypted or decrypted; negative value on error
289 */
crypt_scatterlist(struct ecryptfs_crypt_stat * crypt_stat,struct scatterlist * dst_sg,struct scatterlist * src_sg,int size,unsigned char * iv,int op)290 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
291 struct scatterlist *dst_sg,
292 struct scatterlist *src_sg, int size,
293 unsigned char *iv, int op)
294 {
295 struct skcipher_request *req = NULL;
296 struct extent_crypt_result ecr;
297 int rc = 0;
298
299 if (unlikely(ecryptfs_verbosity > 0)) {
300 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
301 crypt_stat->key_size);
302 ecryptfs_dump_hex(crypt_stat->key,
303 crypt_stat->key_size);
304 }
305
306 init_completion(&ecr.completion);
307
308 mutex_lock(&crypt_stat->cs_tfm_mutex);
309 req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
310 if (!req) {
311 mutex_unlock(&crypt_stat->cs_tfm_mutex);
312 rc = -ENOMEM;
313 goto out;
314 }
315
316 skcipher_request_set_callback(req,
317 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
318 extent_crypt_complete, &ecr);
319 /* Consider doing this once, when the file is opened */
320 if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
321 rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
322 crypt_stat->key_size);
323 if (rc) {
324 ecryptfs_printk(KERN_ERR,
325 "Error setting key; rc = [%d]\n",
326 rc);
327 mutex_unlock(&crypt_stat->cs_tfm_mutex);
328 rc = -EINVAL;
329 goto out;
330 }
331 crypt_stat->flags |= ECRYPTFS_KEY_SET;
332 }
333 mutex_unlock(&crypt_stat->cs_tfm_mutex);
334 skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
335 rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
336 crypto_skcipher_decrypt(req);
337 if (rc == -EINPROGRESS || rc == -EBUSY) {
338 struct extent_crypt_result *ecr = req->base.data;
339
340 wait_for_completion(&ecr->completion);
341 rc = ecr->rc;
342 reinit_completion(&ecr->completion);
343 }
344 out:
345 skcipher_request_free(req);
346 return rc;
347 }
348
349 /*
350 * lower_offset_for_page
351 *
352 * Convert an eCryptfs page index into a lower byte offset
353 */
lower_offset_for_page(struct ecryptfs_crypt_stat * crypt_stat,struct page * page)354 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
355 struct page *page)
356 {
357 return ecryptfs_lower_header_size(crypt_stat) +
358 ((loff_t)page->index << PAGE_SHIFT);
359 }
360
361 /**
362 * crypt_extent
363 * @crypt_stat: crypt_stat containing cryptographic context for the
364 * encryption operation
365 * @dst_page: The page to write the result into
366 * @src_page: The page to read from
367 * @extent_offset: Page extent offset for use in generating IV
368 * @op: ENCRYPT or DECRYPT to indicate the desired operation
369 *
370 * Encrypts or decrypts one extent of data.
371 *
372 * Return zero on success; non-zero otherwise
373 */
crypt_extent(struct ecryptfs_crypt_stat * crypt_stat,struct page * dst_page,struct page * src_page,unsigned long extent_offset,int op)374 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
375 struct page *dst_page,
376 struct page *src_page,
377 unsigned long extent_offset, int op)
378 {
379 pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
380 loff_t extent_base;
381 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
382 struct scatterlist src_sg, dst_sg;
383 size_t extent_size = crypt_stat->extent_size;
384 int rc;
385
386 extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
387 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
388 (extent_base + extent_offset));
389 if (rc) {
390 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
391 "extent [0x%.16llx]; rc = [%d]\n",
392 (unsigned long long)(extent_base + extent_offset), rc);
393 goto out;
394 }
395
396 sg_init_table(&src_sg, 1);
397 sg_init_table(&dst_sg, 1);
398
399 sg_set_page(&src_sg, src_page, extent_size,
400 extent_offset * extent_size);
401 sg_set_page(&dst_sg, dst_page, extent_size,
402 extent_offset * extent_size);
403
404 rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
405 extent_iv, op);
406 if (rc < 0) {
407 printk(KERN_ERR "%s: Error attempting to crypt page with "
408 "page_index = [%ld], extent_offset = [%ld]; "
409 "rc = [%d]\n", __func__, page_index, extent_offset, rc);
410 goto out;
411 }
412 rc = 0;
413 out:
414 return rc;
415 }
416
417 /**
418 * ecryptfs_encrypt_page
419 * @page: Page mapped from the eCryptfs inode for the file; contains
420 * decrypted content that needs to be encrypted (to a temporary
421 * page; not in place) and written out to the lower file
422 *
423 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
424 * that eCryptfs pages may straddle the lower pages -- for instance,
425 * if the file was created on a machine with an 8K page size
426 * (resulting in an 8K header), and then the file is copied onto a
427 * host with a 32K page size, then when reading page 0 of the eCryptfs
428 * file, 24K of page 0 of the lower file will be read and decrypted,
429 * and then 8K of page 1 of the lower file will be read and decrypted.
430 *
431 * Returns zero on success; negative on error
432 */
ecryptfs_encrypt_page(struct page * page)433 int ecryptfs_encrypt_page(struct page *page)
434 {
435 struct inode *ecryptfs_inode;
436 struct ecryptfs_crypt_stat *crypt_stat;
437 char *enc_extent_virt;
438 struct page *enc_extent_page = NULL;
439 loff_t extent_offset;
440 loff_t lower_offset;
441 int rc = 0;
442
443 ecryptfs_inode = page->mapping->host;
444 crypt_stat =
445 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
446 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
447 enc_extent_page = alloc_page(GFP_USER);
448 if (!enc_extent_page) {
449 rc = -ENOMEM;
450 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
451 "encrypted extent\n");
452 goto out;
453 }
454
455 for (extent_offset = 0;
456 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
457 extent_offset++) {
458 rc = crypt_extent(crypt_stat, enc_extent_page, page,
459 extent_offset, ENCRYPT);
460 if (rc) {
461 printk(KERN_ERR "%s: Error encrypting extent; "
462 "rc = [%d]\n", __func__, rc);
463 goto out;
464 }
465 }
466
467 lower_offset = lower_offset_for_page(crypt_stat, page);
468 enc_extent_virt = kmap(enc_extent_page);
469 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
470 PAGE_SIZE);
471 kunmap(enc_extent_page);
472 if (rc < 0) {
473 ecryptfs_printk(KERN_ERR,
474 "Error attempting to write lower page; rc = [%d]\n",
475 rc);
476 goto out;
477 }
478 rc = 0;
479 out:
480 if (enc_extent_page) {
481 __free_page(enc_extent_page);
482 }
483 return rc;
484 }
485
486 /**
487 * ecryptfs_decrypt_page
488 * @page: Page mapped from the eCryptfs inode for the file; data read
489 * and decrypted from the lower file will be written into this
490 * page
491 *
492 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
493 * that eCryptfs pages may straddle the lower pages -- for instance,
494 * if the file was created on a machine with an 8K page size
495 * (resulting in an 8K header), and then the file is copied onto a
496 * host with a 32K page size, then when reading page 0 of the eCryptfs
497 * file, 24K of page 0 of the lower file will be read and decrypted,
498 * and then 8K of page 1 of the lower file will be read and decrypted.
499 *
500 * Returns zero on success; negative on error
501 */
ecryptfs_decrypt_page(struct page * page)502 int ecryptfs_decrypt_page(struct page *page)
503 {
504 struct inode *ecryptfs_inode;
505 struct ecryptfs_crypt_stat *crypt_stat;
506 char *page_virt;
507 unsigned long extent_offset;
508 loff_t lower_offset;
509 int rc = 0;
510
511 ecryptfs_inode = page->mapping->host;
512 crypt_stat =
513 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
514 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
515
516 lower_offset = lower_offset_for_page(crypt_stat, page);
517 page_virt = kmap(page);
518 rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
519 ecryptfs_inode);
520 kunmap(page);
521 if (rc < 0) {
522 ecryptfs_printk(KERN_ERR,
523 "Error attempting to read lower page; rc = [%d]\n",
524 rc);
525 goto out;
526 }
527
528 for (extent_offset = 0;
529 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
530 extent_offset++) {
531 rc = crypt_extent(crypt_stat, page, page,
532 extent_offset, DECRYPT);
533 if (rc) {
534 printk(KERN_ERR "%s: Error decrypting extent; "
535 "rc = [%d]\n", __func__, rc);
536 goto out;
537 }
538 }
539 out:
540 return rc;
541 }
542
543 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
544
545 /**
546 * ecryptfs_init_crypt_ctx
547 * @crypt_stat: Uninitialized crypt stats structure
548 *
549 * Initialize the crypto context.
550 *
551 * TODO: Performance: Keep a cache of initialized cipher contexts;
552 * only init if needed
553 */
ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat * crypt_stat)554 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
555 {
556 char *full_alg_name;
557 int rc = -EINVAL;
558
559 ecryptfs_printk(KERN_DEBUG,
560 "Initializing cipher [%s]; strlen = [%d]; "
561 "key_size_bits = [%zd]\n",
562 crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
563 crypt_stat->key_size << 3);
564 mutex_lock(&crypt_stat->cs_tfm_mutex);
565 if (crypt_stat->tfm) {
566 rc = 0;
567 goto out_unlock;
568 }
569 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
570 crypt_stat->cipher, "cbc");
571 if (rc)
572 goto out_unlock;
573 crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
574 if (IS_ERR(crypt_stat->tfm)) {
575 rc = PTR_ERR(crypt_stat->tfm);
576 crypt_stat->tfm = NULL;
577 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
578 "Error initializing cipher [%s]\n",
579 full_alg_name);
580 goto out_free;
581 }
582 crypto_skcipher_set_flags(crypt_stat->tfm,
583 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
584 rc = 0;
585 out_free:
586 kfree(full_alg_name);
587 out_unlock:
588 mutex_unlock(&crypt_stat->cs_tfm_mutex);
589 return rc;
590 }
591
set_extent_mask_and_shift(struct ecryptfs_crypt_stat * crypt_stat)592 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
593 {
594 int extent_size_tmp;
595
596 crypt_stat->extent_mask = 0xFFFFFFFF;
597 crypt_stat->extent_shift = 0;
598 if (crypt_stat->extent_size == 0)
599 return;
600 extent_size_tmp = crypt_stat->extent_size;
601 while ((extent_size_tmp & 0x01) == 0) {
602 extent_size_tmp >>= 1;
603 crypt_stat->extent_mask <<= 1;
604 crypt_stat->extent_shift++;
605 }
606 }
607
ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat * crypt_stat)608 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
609 {
610 /* Default values; may be overwritten as we are parsing the
611 * packets. */
612 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
613 set_extent_mask_and_shift(crypt_stat);
614 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
615 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
616 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
617 else {
618 if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
619 crypt_stat->metadata_size =
620 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
621 else
622 crypt_stat->metadata_size = PAGE_SIZE;
623 }
624 }
625
626 /*
627 * ecryptfs_compute_root_iv
628 *
629 * On error, sets the root IV to all 0's.
630 */
ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat * crypt_stat)631 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
632 {
633 int rc = 0;
634 char dst[MD5_DIGEST_SIZE];
635
636 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
637 BUG_ON(crypt_stat->iv_bytes <= 0);
638 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
639 rc = -EINVAL;
640 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
641 "cannot generate root IV\n");
642 goto out;
643 }
644 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
645 crypt_stat->key_size);
646 if (rc) {
647 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
648 "MD5 while generating root IV\n");
649 goto out;
650 }
651 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
652 out:
653 if (rc) {
654 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
655 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
656 }
657 return rc;
658 }
659
ecryptfs_generate_new_key(struct ecryptfs_crypt_stat * crypt_stat)660 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
661 {
662 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
663 crypt_stat->flags |= ECRYPTFS_KEY_VALID;
664 ecryptfs_compute_root_iv(crypt_stat);
665 if (unlikely(ecryptfs_verbosity > 0)) {
666 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
667 ecryptfs_dump_hex(crypt_stat->key,
668 crypt_stat->key_size);
669 }
670 }
671
672 /**
673 * ecryptfs_copy_mount_wide_flags_to_inode_flags
674 * @crypt_stat: The inode's cryptographic context
675 * @mount_crypt_stat: The mount point's cryptographic context
676 *
677 * This function propagates the mount-wide flags to individual inode
678 * flags.
679 */
ecryptfs_copy_mount_wide_flags_to_inode_flags(struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)680 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
681 struct ecryptfs_crypt_stat *crypt_stat,
682 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
683 {
684 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
685 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
686 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
687 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
688 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
689 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
690 if (mount_crypt_stat->flags
691 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
692 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
693 else if (mount_crypt_stat->flags
694 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
695 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
696 }
697 }
698
ecryptfs_copy_mount_wide_sigs_to_inode_sigs(struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)699 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
700 struct ecryptfs_crypt_stat *crypt_stat,
701 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
702 {
703 struct ecryptfs_global_auth_tok *global_auth_tok;
704 int rc = 0;
705
706 mutex_lock(&crypt_stat->keysig_list_mutex);
707 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
708
709 list_for_each_entry(global_auth_tok,
710 &mount_crypt_stat->global_auth_tok_list,
711 mount_crypt_stat_list) {
712 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
713 continue;
714 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
715 if (rc) {
716 printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
717 goto out;
718 }
719 }
720
721 out:
722 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
723 mutex_unlock(&crypt_stat->keysig_list_mutex);
724 return rc;
725 }
726
727 /**
728 * ecryptfs_set_default_crypt_stat_vals
729 * @crypt_stat: The inode's cryptographic context
730 * @mount_crypt_stat: The mount point's cryptographic context
731 *
732 * Default values in the event that policy does not override them.
733 */
ecryptfs_set_default_crypt_stat_vals(struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)734 static void ecryptfs_set_default_crypt_stat_vals(
735 struct ecryptfs_crypt_stat *crypt_stat,
736 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
737 {
738 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
739 mount_crypt_stat);
740 ecryptfs_set_default_sizes(crypt_stat);
741 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
742 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
743 crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
744 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
745 crypt_stat->mount_crypt_stat = mount_crypt_stat;
746 }
747
748 /**
749 * ecryptfs_new_file_context
750 * @ecryptfs_inode: The eCryptfs inode
751 *
752 * If the crypto context for the file has not yet been established,
753 * this is where we do that. Establishing a new crypto context
754 * involves the following decisions:
755 * - What cipher to use?
756 * - What set of authentication tokens to use?
757 * Here we just worry about getting enough information into the
758 * authentication tokens so that we know that they are available.
759 * We associate the available authentication tokens with the new file
760 * via the set of signatures in the crypt_stat struct. Later, when
761 * the headers are actually written out, we may again defer to
762 * userspace to perform the encryption of the session key; for the
763 * foreseeable future, this will be the case with public key packets.
764 *
765 * Returns zero on success; non-zero otherwise
766 */
ecryptfs_new_file_context(struct inode * ecryptfs_inode)767 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
768 {
769 struct ecryptfs_crypt_stat *crypt_stat =
770 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
771 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
772 &ecryptfs_superblock_to_private(
773 ecryptfs_inode->i_sb)->mount_crypt_stat;
774 int cipher_name_len;
775 int rc = 0;
776
777 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
778 crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
779 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
780 mount_crypt_stat);
781 rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
782 mount_crypt_stat);
783 if (rc) {
784 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
785 "to the inode key sigs; rc = [%d]\n", rc);
786 goto out;
787 }
788 cipher_name_len =
789 strlen(mount_crypt_stat->global_default_cipher_name);
790 memcpy(crypt_stat->cipher,
791 mount_crypt_stat->global_default_cipher_name,
792 cipher_name_len);
793 crypt_stat->cipher[cipher_name_len] = '\0';
794 crypt_stat->key_size =
795 mount_crypt_stat->global_default_cipher_key_size;
796 ecryptfs_generate_new_key(crypt_stat);
797 rc = ecryptfs_init_crypt_ctx(crypt_stat);
798 if (rc)
799 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
800 "context for cipher [%s]: rc = [%d]\n",
801 crypt_stat->cipher, rc);
802 out:
803 return rc;
804 }
805
806 /**
807 * ecryptfs_validate_marker - check for the ecryptfs marker
808 * @data: The data block in which to check
809 *
810 * Returns zero if marker found; -EINVAL if not found
811 */
ecryptfs_validate_marker(char * data)812 static int ecryptfs_validate_marker(char *data)
813 {
814 u32 m_1, m_2;
815
816 m_1 = get_unaligned_be32(data);
817 m_2 = get_unaligned_be32(data + 4);
818 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
819 return 0;
820 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
821 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
822 MAGIC_ECRYPTFS_MARKER);
823 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
824 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
825 return -EINVAL;
826 }
827
828 struct ecryptfs_flag_map_elem {
829 u32 file_flag;
830 u32 local_flag;
831 };
832
833 /* Add support for additional flags by adding elements here. */
834 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
835 {0x00000001, ECRYPTFS_ENABLE_HMAC},
836 {0x00000002, ECRYPTFS_ENCRYPTED},
837 {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
838 {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
839 };
840
841 /**
842 * ecryptfs_process_flags
843 * @crypt_stat: The cryptographic context
844 * @page_virt: Source data to be parsed
845 * @bytes_read: Updated with the number of bytes read
846 */
ecryptfs_process_flags(struct ecryptfs_crypt_stat * crypt_stat,char * page_virt,int * bytes_read)847 static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
848 char *page_virt, int *bytes_read)
849 {
850 int i;
851 u32 flags;
852
853 flags = get_unaligned_be32(page_virt);
854 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
855 if (flags & ecryptfs_flag_map[i].file_flag) {
856 crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
857 } else
858 crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
859 /* Version is in top 8 bits of the 32-bit flag vector */
860 crypt_stat->file_version = ((flags >> 24) & 0xFF);
861 (*bytes_read) = 4;
862 }
863
864 /**
865 * write_ecryptfs_marker
866 * @page_virt: The pointer to in a page to begin writing the marker
867 * @written: Number of bytes written
868 *
869 * Marker = 0x3c81b7f5
870 */
write_ecryptfs_marker(char * page_virt,size_t * written)871 static void write_ecryptfs_marker(char *page_virt, size_t *written)
872 {
873 u32 m_1, m_2;
874
875 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
876 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
877 put_unaligned_be32(m_1, page_virt);
878 page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
879 put_unaligned_be32(m_2, page_virt);
880 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
881 }
882
ecryptfs_write_crypt_stat_flags(char * page_virt,struct ecryptfs_crypt_stat * crypt_stat,size_t * written)883 void ecryptfs_write_crypt_stat_flags(char *page_virt,
884 struct ecryptfs_crypt_stat *crypt_stat,
885 size_t *written)
886 {
887 u32 flags = 0;
888 int i;
889
890 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
891 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
892 flags |= ecryptfs_flag_map[i].file_flag;
893 /* Version is in top 8 bits of the 32-bit flag vector */
894 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
895 put_unaligned_be32(flags, page_virt);
896 (*written) = 4;
897 }
898
899 struct ecryptfs_cipher_code_str_map_elem {
900 char cipher_str[16];
901 u8 cipher_code;
902 };
903
904 /* Add support for additional ciphers by adding elements here. The
905 * cipher_code is whatever OpenPGP applications use to identify the
906 * ciphers. List in order of probability. */
907 static struct ecryptfs_cipher_code_str_map_elem
908 ecryptfs_cipher_code_str_map[] = {
909 {"aes",RFC2440_CIPHER_AES_128 },
910 {"blowfish", RFC2440_CIPHER_BLOWFISH},
911 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
912 {"cast5", RFC2440_CIPHER_CAST_5},
913 {"twofish", RFC2440_CIPHER_TWOFISH},
914 {"cast6", RFC2440_CIPHER_CAST_6},
915 {"aes", RFC2440_CIPHER_AES_192},
916 {"aes", RFC2440_CIPHER_AES_256}
917 };
918
919 /**
920 * ecryptfs_code_for_cipher_string
921 * @cipher_name: The string alias for the cipher
922 * @key_bytes: Length of key in bytes; used for AES code selection
923 *
924 * Returns zero on no match, or the cipher code on match
925 */
ecryptfs_code_for_cipher_string(char * cipher_name,size_t key_bytes)926 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
927 {
928 int i;
929 u8 code = 0;
930 struct ecryptfs_cipher_code_str_map_elem *map =
931 ecryptfs_cipher_code_str_map;
932
933 if (strcmp(cipher_name, "aes") == 0) {
934 switch (key_bytes) {
935 case 16:
936 code = RFC2440_CIPHER_AES_128;
937 break;
938 case 24:
939 code = RFC2440_CIPHER_AES_192;
940 break;
941 case 32:
942 code = RFC2440_CIPHER_AES_256;
943 }
944 } else {
945 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
946 if (strcmp(cipher_name, map[i].cipher_str) == 0) {
947 code = map[i].cipher_code;
948 break;
949 }
950 }
951 return code;
952 }
953
954 /**
955 * ecryptfs_cipher_code_to_string
956 * @str: Destination to write out the cipher name
957 * @cipher_code: The code to convert to cipher name string
958 *
959 * Returns zero on success
960 */
ecryptfs_cipher_code_to_string(char * str,u8 cipher_code)961 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
962 {
963 int rc = 0;
964 int i;
965
966 str[0] = '\0';
967 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
968 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
969 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
970 if (str[0] == '\0') {
971 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
972 "[%d]\n", cipher_code);
973 rc = -EINVAL;
974 }
975 return rc;
976 }
977
ecryptfs_read_and_validate_header_region(struct inode * inode)978 int ecryptfs_read_and_validate_header_region(struct inode *inode)
979 {
980 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
981 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
982 int rc;
983
984 rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
985 inode);
986 if (rc < 0)
987 return rc;
988 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
989 return -EINVAL;
990 rc = ecryptfs_validate_marker(marker);
991 if (!rc)
992 ecryptfs_i_size_init(file_size, inode);
993 return rc;
994 }
995
996 void
ecryptfs_write_header_metadata(char * virt,struct ecryptfs_crypt_stat * crypt_stat,size_t * written)997 ecryptfs_write_header_metadata(char *virt,
998 struct ecryptfs_crypt_stat *crypt_stat,
999 size_t *written)
1000 {
1001 u32 header_extent_size;
1002 u16 num_header_extents_at_front;
1003
1004 header_extent_size = (u32)crypt_stat->extent_size;
1005 num_header_extents_at_front =
1006 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1007 put_unaligned_be32(header_extent_size, virt);
1008 virt += 4;
1009 put_unaligned_be16(num_header_extents_at_front, virt);
1010 (*written) = 6;
1011 }
1012
1013 struct kmem_cache *ecryptfs_header_cache;
1014
1015 /**
1016 * ecryptfs_write_headers_virt
1017 * @page_virt: The virtual address to write the headers to
1018 * @max: The size of memory allocated at page_virt
1019 * @size: Set to the number of bytes written by this function
1020 * @crypt_stat: The cryptographic context
1021 * @ecryptfs_dentry: The eCryptfs dentry
1022 *
1023 * Format version: 1
1024 *
1025 * Header Extent:
1026 * Octets 0-7: Unencrypted file size (big-endian)
1027 * Octets 8-15: eCryptfs special marker
1028 * Octets 16-19: Flags
1029 * Octet 16: File format version number (between 0 and 255)
1030 * Octets 17-18: Reserved
1031 * Octet 19: Bit 1 (lsb): Reserved
1032 * Bit 2: Encrypted?
1033 * Bits 3-8: Reserved
1034 * Octets 20-23: Header extent size (big-endian)
1035 * Octets 24-25: Number of header extents at front of file
1036 * (big-endian)
1037 * Octet 26: Begin RFC 2440 authentication token packet set
1038 * Data Extent 0:
1039 * Lower data (CBC encrypted)
1040 * Data Extent 1:
1041 * Lower data (CBC encrypted)
1042 * ...
1043 *
1044 * Returns zero on success
1045 */
ecryptfs_write_headers_virt(char * page_virt,size_t max,size_t * size,struct ecryptfs_crypt_stat * crypt_stat,struct dentry * ecryptfs_dentry)1046 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1047 size_t *size,
1048 struct ecryptfs_crypt_stat *crypt_stat,
1049 struct dentry *ecryptfs_dentry)
1050 {
1051 int rc;
1052 size_t written;
1053 size_t offset;
1054
1055 offset = ECRYPTFS_FILE_SIZE_BYTES;
1056 write_ecryptfs_marker((page_virt + offset), &written);
1057 offset += written;
1058 ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1059 &written);
1060 offset += written;
1061 ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1062 &written);
1063 offset += written;
1064 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1065 ecryptfs_dentry, &written,
1066 max - offset);
1067 if (rc)
1068 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1069 "set; rc = [%d]\n", rc);
1070 if (size) {
1071 offset += written;
1072 *size = offset;
1073 }
1074 return rc;
1075 }
1076
1077 static int
ecryptfs_write_metadata_to_contents(struct inode * ecryptfs_inode,char * virt,size_t virt_len)1078 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1079 char *virt, size_t virt_len)
1080 {
1081 int rc;
1082
1083 rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1084 0, virt_len);
1085 if (rc < 0)
1086 printk(KERN_ERR "%s: Error attempting to write header "
1087 "information to lower file; rc = [%d]\n", __func__, rc);
1088 else
1089 rc = 0;
1090 return rc;
1091 }
1092
1093 static int
ecryptfs_write_metadata_to_xattr(struct dentry * ecryptfs_dentry,struct inode * ecryptfs_inode,char * page_virt,size_t size)1094 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1095 struct inode *ecryptfs_inode,
1096 char *page_virt, size_t size)
1097 {
1098 int rc;
1099 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
1100 struct inode *lower_inode = d_inode(lower_dentry);
1101
1102 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1103 rc = -EOPNOTSUPP;
1104 goto out;
1105 }
1106
1107 inode_lock(lower_inode);
1108 rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode,
1109 ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1110 if (!rc && ecryptfs_inode)
1111 fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
1112 inode_unlock(lower_inode);
1113 out:
1114 return rc;
1115 }
1116
ecryptfs_get_zeroed_pages(gfp_t gfp_mask,unsigned int order)1117 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1118 unsigned int order)
1119 {
1120 struct page *page;
1121
1122 page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1123 if (page)
1124 return (unsigned long) page_address(page);
1125 return 0;
1126 }
1127
1128 /**
1129 * ecryptfs_write_metadata
1130 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1131 * @ecryptfs_inode: The newly created eCryptfs inode
1132 *
1133 * Write the file headers out. This will likely involve a userspace
1134 * callout, in which the session key is encrypted with one or more
1135 * public keys and/or the passphrase necessary to do the encryption is
1136 * retrieved via a prompt. Exactly what happens at this point should
1137 * be policy-dependent.
1138 *
1139 * Returns zero on success; non-zero on error
1140 */
ecryptfs_write_metadata(struct dentry * ecryptfs_dentry,struct inode * ecryptfs_inode)1141 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1142 struct inode *ecryptfs_inode)
1143 {
1144 struct ecryptfs_crypt_stat *crypt_stat =
1145 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1146 unsigned int order;
1147 char *virt;
1148 size_t virt_len;
1149 size_t size = 0;
1150 int rc = 0;
1151
1152 if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1153 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1154 printk(KERN_ERR "Key is invalid; bailing out\n");
1155 rc = -EINVAL;
1156 goto out;
1157 }
1158 } else {
1159 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1160 __func__);
1161 rc = -EINVAL;
1162 goto out;
1163 }
1164 virt_len = crypt_stat->metadata_size;
1165 order = get_order(virt_len);
1166 /* Released in this function */
1167 virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1168 if (!virt) {
1169 printk(KERN_ERR "%s: Out of memory\n", __func__);
1170 rc = -ENOMEM;
1171 goto out;
1172 }
1173 /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1174 rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1175 ecryptfs_dentry);
1176 if (unlikely(rc)) {
1177 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1178 __func__, rc);
1179 goto out_free;
1180 }
1181 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1182 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1183 virt, size);
1184 else
1185 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1186 virt_len);
1187 if (rc) {
1188 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1189 "rc = [%d]\n", __func__, rc);
1190 goto out_free;
1191 }
1192 out_free:
1193 free_pages((unsigned long)virt, order);
1194 out:
1195 return rc;
1196 }
1197
1198 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1199 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
parse_header_metadata(struct ecryptfs_crypt_stat * crypt_stat,char * virt,int * bytes_read,int validate_header_size)1200 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1201 char *virt, int *bytes_read,
1202 int validate_header_size)
1203 {
1204 int rc = 0;
1205 u32 header_extent_size;
1206 u16 num_header_extents_at_front;
1207
1208 header_extent_size = get_unaligned_be32(virt);
1209 virt += sizeof(__be32);
1210 num_header_extents_at_front = get_unaligned_be16(virt);
1211 crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1212 * (size_t)header_extent_size));
1213 (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1214 if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1215 && (crypt_stat->metadata_size
1216 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1217 rc = -EINVAL;
1218 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1219 crypt_stat->metadata_size);
1220 }
1221 return rc;
1222 }
1223
1224 /**
1225 * set_default_header_data
1226 * @crypt_stat: The cryptographic context
1227 *
1228 * For version 0 file format; this function is only for backwards
1229 * compatibility for files created with the prior versions of
1230 * eCryptfs.
1231 */
set_default_header_data(struct ecryptfs_crypt_stat * crypt_stat)1232 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1233 {
1234 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1235 }
1236
ecryptfs_i_size_init(const char * page_virt,struct inode * inode)1237 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1238 {
1239 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1240 struct ecryptfs_crypt_stat *crypt_stat;
1241 u64 file_size;
1242
1243 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1244 mount_crypt_stat =
1245 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1246 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1247 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1248 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1249 file_size += crypt_stat->metadata_size;
1250 } else
1251 file_size = get_unaligned_be64(page_virt);
1252 i_size_write(inode, (loff_t)file_size);
1253 crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1254 }
1255
1256 /**
1257 * ecryptfs_read_headers_virt
1258 * @page_virt: The virtual address into which to read the headers
1259 * @crypt_stat: The cryptographic context
1260 * @ecryptfs_dentry: The eCryptfs dentry
1261 * @validate_header_size: Whether to validate the header size while reading
1262 *
1263 * Read/parse the header data. The header format is detailed in the
1264 * comment block for the ecryptfs_write_headers_virt() function.
1265 *
1266 * Returns zero on success
1267 */
ecryptfs_read_headers_virt(char * page_virt,struct ecryptfs_crypt_stat * crypt_stat,struct dentry * ecryptfs_dentry,int validate_header_size)1268 static int ecryptfs_read_headers_virt(char *page_virt,
1269 struct ecryptfs_crypt_stat *crypt_stat,
1270 struct dentry *ecryptfs_dentry,
1271 int validate_header_size)
1272 {
1273 int rc = 0;
1274 int offset;
1275 int bytes_read;
1276
1277 ecryptfs_set_default_sizes(crypt_stat);
1278 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1279 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1280 offset = ECRYPTFS_FILE_SIZE_BYTES;
1281 rc = ecryptfs_validate_marker(page_virt + offset);
1282 if (rc)
1283 goto out;
1284 if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1285 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1286 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1287 ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
1288 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1289 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1290 "file version [%d] is supported by this "
1291 "version of eCryptfs\n",
1292 crypt_stat->file_version,
1293 ECRYPTFS_SUPPORTED_FILE_VERSION);
1294 rc = -EINVAL;
1295 goto out;
1296 }
1297 offset += bytes_read;
1298 if (crypt_stat->file_version >= 1) {
1299 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1300 &bytes_read, validate_header_size);
1301 if (rc) {
1302 ecryptfs_printk(KERN_WARNING, "Error reading header "
1303 "metadata; rc = [%d]\n", rc);
1304 }
1305 offset += bytes_read;
1306 } else
1307 set_default_header_data(crypt_stat);
1308 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1309 ecryptfs_dentry);
1310 out:
1311 return rc;
1312 }
1313
1314 /**
1315 * ecryptfs_read_xattr_region
1316 * @page_virt: The vitual address into which to read the xattr data
1317 * @ecryptfs_inode: The eCryptfs inode
1318 *
1319 * Attempts to read the crypto metadata from the extended attribute
1320 * region of the lower file.
1321 *
1322 * Returns zero on success; non-zero on error
1323 */
ecryptfs_read_xattr_region(char * page_virt,struct inode * ecryptfs_inode)1324 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1325 {
1326 struct dentry *lower_dentry =
1327 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1328 ssize_t size;
1329 int rc = 0;
1330
1331 size = ecryptfs_getxattr_lower(lower_dentry,
1332 ecryptfs_inode_to_lower(ecryptfs_inode),
1333 ECRYPTFS_XATTR_NAME,
1334 page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1335 if (size < 0) {
1336 if (unlikely(ecryptfs_verbosity > 0))
1337 printk(KERN_INFO "Error attempting to read the [%s] "
1338 "xattr from the lower file; return value = "
1339 "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1340 rc = -EINVAL;
1341 goto out;
1342 }
1343 out:
1344 return rc;
1345 }
1346
ecryptfs_read_and_validate_xattr_region(struct dentry * dentry,struct inode * inode)1347 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1348 struct inode *inode)
1349 {
1350 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1351 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1352 int rc;
1353
1354 rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1355 ecryptfs_inode_to_lower(inode),
1356 ECRYPTFS_XATTR_NAME, file_size,
1357 ECRYPTFS_SIZE_AND_MARKER_BYTES);
1358 if (rc < 0)
1359 return rc;
1360 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1361 return -EINVAL;
1362 rc = ecryptfs_validate_marker(marker);
1363 if (!rc)
1364 ecryptfs_i_size_init(file_size, inode);
1365 return rc;
1366 }
1367
1368 /*
1369 * ecryptfs_read_metadata
1370 *
1371 * Common entry point for reading file metadata. From here, we could
1372 * retrieve the header information from the header region of the file,
1373 * the xattr region of the file, or some other repository that is
1374 * stored separately from the file itself. The current implementation
1375 * supports retrieving the metadata information from the file contents
1376 * and from the xattr region.
1377 *
1378 * Returns zero if valid headers found and parsed; non-zero otherwise
1379 */
ecryptfs_read_metadata(struct dentry * ecryptfs_dentry)1380 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1381 {
1382 int rc;
1383 char *page_virt;
1384 struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1385 struct ecryptfs_crypt_stat *crypt_stat =
1386 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1387 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1388 &ecryptfs_superblock_to_private(
1389 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1390
1391 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1392 mount_crypt_stat);
1393 /* Read the first page from the underlying file */
1394 page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1395 if (!page_virt) {
1396 rc = -ENOMEM;
1397 goto out;
1398 }
1399 rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1400 ecryptfs_inode);
1401 if (rc >= 0)
1402 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1403 ecryptfs_dentry,
1404 ECRYPTFS_VALIDATE_HEADER_SIZE);
1405 if (rc) {
1406 /* metadata is not in the file header, so try xattrs */
1407 memset(page_virt, 0, PAGE_SIZE);
1408 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1409 if (rc) {
1410 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1411 "file header region or xattr region, inode %lu\n",
1412 ecryptfs_inode->i_ino);
1413 rc = -EINVAL;
1414 goto out;
1415 }
1416 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1417 ecryptfs_dentry,
1418 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1419 if (rc) {
1420 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1421 "file xattr region either, inode %lu\n",
1422 ecryptfs_inode->i_ino);
1423 rc = -EINVAL;
1424 }
1425 if (crypt_stat->mount_crypt_stat->flags
1426 & ECRYPTFS_XATTR_METADATA_ENABLED) {
1427 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1428 } else {
1429 printk(KERN_WARNING "Attempt to access file with "
1430 "crypto metadata only in the extended attribute "
1431 "region, but eCryptfs was mounted without "
1432 "xattr support enabled. eCryptfs will not treat "
1433 "this like an encrypted file, inode %lu\n",
1434 ecryptfs_inode->i_ino);
1435 rc = -EINVAL;
1436 }
1437 }
1438 out:
1439 if (page_virt) {
1440 memset(page_virt, 0, PAGE_SIZE);
1441 kmem_cache_free(ecryptfs_header_cache, page_virt);
1442 }
1443 return rc;
1444 }
1445
1446 /*
1447 * ecryptfs_encrypt_filename - encrypt filename
1448 *
1449 * CBC-encrypts the filename. We do not want to encrypt the same
1450 * filename with the same key and IV, which may happen with hard
1451 * links, so we prepend random bits to each filename.
1452 *
1453 * Returns zero on success; non-zero otherwise
1454 */
1455 static int
ecryptfs_encrypt_filename(struct ecryptfs_filename * filename,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)1456 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1457 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1458 {
1459 int rc = 0;
1460
1461 filename->encrypted_filename = NULL;
1462 filename->encrypted_filename_size = 0;
1463 if (mount_crypt_stat && (mount_crypt_stat->flags
1464 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1465 size_t packet_size;
1466 size_t remaining_bytes;
1467
1468 rc = ecryptfs_write_tag_70_packet(
1469 NULL, NULL,
1470 &filename->encrypted_filename_size,
1471 mount_crypt_stat, NULL,
1472 filename->filename_size);
1473 if (rc) {
1474 printk(KERN_ERR "%s: Error attempting to get packet "
1475 "size for tag 72; rc = [%d]\n", __func__,
1476 rc);
1477 filename->encrypted_filename_size = 0;
1478 goto out;
1479 }
1480 filename->encrypted_filename =
1481 kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1482 if (!filename->encrypted_filename) {
1483 rc = -ENOMEM;
1484 goto out;
1485 }
1486 remaining_bytes = filename->encrypted_filename_size;
1487 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1488 &remaining_bytes,
1489 &packet_size,
1490 mount_crypt_stat,
1491 filename->filename,
1492 filename->filename_size);
1493 if (rc) {
1494 printk(KERN_ERR "%s: Error attempting to generate "
1495 "tag 70 packet; rc = [%d]\n", __func__,
1496 rc);
1497 kfree(filename->encrypted_filename);
1498 filename->encrypted_filename = NULL;
1499 filename->encrypted_filename_size = 0;
1500 goto out;
1501 }
1502 filename->encrypted_filename_size = packet_size;
1503 } else {
1504 printk(KERN_ERR "%s: No support for requested filename "
1505 "encryption method in this release\n", __func__);
1506 rc = -EOPNOTSUPP;
1507 goto out;
1508 }
1509 out:
1510 return rc;
1511 }
1512
ecryptfs_copy_filename(char ** copied_name,size_t * copied_name_size,const char * name,size_t name_size)1513 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1514 const char *name, size_t name_size)
1515 {
1516 int rc = 0;
1517
1518 (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1519 if (!(*copied_name)) {
1520 rc = -ENOMEM;
1521 goto out;
1522 }
1523 memcpy((void *)(*copied_name), (void *)name, name_size);
1524 (*copied_name)[(name_size)] = '\0'; /* Only for convenience
1525 * in printing out the
1526 * string in debug
1527 * messages */
1528 (*copied_name_size) = name_size;
1529 out:
1530 return rc;
1531 }
1532
1533 /**
1534 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1535 * @key_tfm: Crypto context for key material, set by this function
1536 * @cipher_name: Name of the cipher
1537 * @key_size: Size of the key in bytes
1538 *
1539 * Returns zero on success. Any crypto_tfm structs allocated here
1540 * should be released by other functions, such as on a superblock put
1541 * event, regardless of whether this function succeeds for fails.
1542 */
1543 static int
ecryptfs_process_key_cipher(struct crypto_skcipher ** key_tfm,char * cipher_name,size_t * key_size)1544 ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1545 char *cipher_name, size_t *key_size)
1546 {
1547 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1548 char *full_alg_name = NULL;
1549 int rc;
1550
1551 *key_tfm = NULL;
1552 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1553 rc = -EINVAL;
1554 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1555 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1556 goto out;
1557 }
1558 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1559 "ecb");
1560 if (rc)
1561 goto out;
1562 *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1563 if (IS_ERR(*key_tfm)) {
1564 rc = PTR_ERR(*key_tfm);
1565 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1566 "[%s]; rc = [%d]\n", full_alg_name, rc);
1567 goto out;
1568 }
1569 crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1570 if (*key_size == 0)
1571 *key_size = crypto_skcipher_max_keysize(*key_tfm);
1572 get_random_bytes(dummy_key, *key_size);
1573 rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1574 if (rc) {
1575 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1576 "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1577 rc);
1578 rc = -EINVAL;
1579 goto out;
1580 }
1581 out:
1582 kfree(full_alg_name);
1583 return rc;
1584 }
1585
1586 struct kmem_cache *ecryptfs_key_tfm_cache;
1587 static struct list_head key_tfm_list;
1588 DEFINE_MUTEX(key_tfm_list_mutex);
1589
ecryptfs_init_crypto(void)1590 int __init ecryptfs_init_crypto(void)
1591 {
1592 INIT_LIST_HEAD(&key_tfm_list);
1593 return 0;
1594 }
1595
1596 /**
1597 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1598 *
1599 * Called only at module unload time
1600 */
ecryptfs_destroy_crypto(void)1601 int ecryptfs_destroy_crypto(void)
1602 {
1603 struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1604
1605 mutex_lock(&key_tfm_list_mutex);
1606 list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1607 key_tfm_list) {
1608 list_del(&key_tfm->key_tfm_list);
1609 crypto_free_skcipher(key_tfm->key_tfm);
1610 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1611 }
1612 mutex_unlock(&key_tfm_list_mutex);
1613 return 0;
1614 }
1615
1616 int
ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm ** key_tfm,char * cipher_name,size_t key_size)1617 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1618 size_t key_size)
1619 {
1620 struct ecryptfs_key_tfm *tmp_tfm;
1621 int rc = 0;
1622
1623 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1624
1625 tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1626 if (key_tfm)
1627 (*key_tfm) = tmp_tfm;
1628 if (!tmp_tfm) {
1629 rc = -ENOMEM;
1630 goto out;
1631 }
1632 mutex_init(&tmp_tfm->key_tfm_mutex);
1633 strncpy(tmp_tfm->cipher_name, cipher_name,
1634 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1635 tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1636 tmp_tfm->key_size = key_size;
1637 rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1638 tmp_tfm->cipher_name,
1639 &tmp_tfm->key_size);
1640 if (rc) {
1641 printk(KERN_ERR "Error attempting to initialize key TFM "
1642 "cipher with name = [%s]; rc = [%d]\n",
1643 tmp_tfm->cipher_name, rc);
1644 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1645 if (key_tfm)
1646 (*key_tfm) = NULL;
1647 goto out;
1648 }
1649 list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1650 out:
1651 return rc;
1652 }
1653
1654 /**
1655 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1656 * @cipher_name: the name of the cipher to search for
1657 * @key_tfm: set to corresponding tfm if found
1658 *
1659 * Searches for cached key_tfm matching @cipher_name
1660 * Must be called with &key_tfm_list_mutex held
1661 * Returns 1 if found, with @key_tfm set
1662 * Returns 0 if not found, with @key_tfm set to NULL
1663 */
ecryptfs_tfm_exists(char * cipher_name,struct ecryptfs_key_tfm ** key_tfm)1664 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1665 {
1666 struct ecryptfs_key_tfm *tmp_key_tfm;
1667
1668 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1669
1670 list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1671 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1672 if (key_tfm)
1673 (*key_tfm) = tmp_key_tfm;
1674 return 1;
1675 }
1676 }
1677 if (key_tfm)
1678 (*key_tfm) = NULL;
1679 return 0;
1680 }
1681
1682 /**
1683 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1684 *
1685 * @tfm: set to cached tfm found, or new tfm created
1686 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1687 * @cipher_name: the name of the cipher to search for and/or add
1688 *
1689 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1690 * Searches for cached item first, and creates new if not found.
1691 * Returns 0 on success, non-zero if adding new cipher failed
1692 */
ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher ** tfm,struct mutex ** tfm_mutex,char * cipher_name)1693 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1694 struct mutex **tfm_mutex,
1695 char *cipher_name)
1696 {
1697 struct ecryptfs_key_tfm *key_tfm;
1698 int rc = 0;
1699
1700 (*tfm) = NULL;
1701 (*tfm_mutex) = NULL;
1702
1703 mutex_lock(&key_tfm_list_mutex);
1704 if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1705 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1706 if (rc) {
1707 printk(KERN_ERR "Error adding new key_tfm to list; "
1708 "rc = [%d]\n", rc);
1709 goto out;
1710 }
1711 }
1712 (*tfm) = key_tfm->key_tfm;
1713 (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1714 out:
1715 mutex_unlock(&key_tfm_list_mutex);
1716 return rc;
1717 }
1718
1719 /* 64 characters forming a 6-bit target field */
1720 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1721 "EFGHIJKLMNOPQRST"
1722 "UVWXYZabcdefghij"
1723 "klmnopqrstuvwxyz");
1724
1725 /* We could either offset on every reverse map or just pad some 0x00's
1726 * at the front here */
1727 static const unsigned char filename_rev_map[256] = {
1728 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1729 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1730 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1731 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1732 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1733 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1734 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1735 0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1736 0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1737 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1738 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1739 0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1740 0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1741 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1742 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1743 0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1744 };
1745
1746 /**
1747 * ecryptfs_encode_for_filename
1748 * @dst: Destination location for encoded filename
1749 * @dst_size: Size of the encoded filename in bytes
1750 * @src: Source location for the filename to encode
1751 * @src_size: Size of the source in bytes
1752 */
ecryptfs_encode_for_filename(unsigned char * dst,size_t * dst_size,unsigned char * src,size_t src_size)1753 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1754 unsigned char *src, size_t src_size)
1755 {
1756 size_t num_blocks;
1757 size_t block_num = 0;
1758 size_t dst_offset = 0;
1759 unsigned char last_block[3];
1760
1761 if (src_size == 0) {
1762 (*dst_size) = 0;
1763 goto out;
1764 }
1765 num_blocks = (src_size / 3);
1766 if ((src_size % 3) == 0) {
1767 memcpy(last_block, (&src[src_size - 3]), 3);
1768 } else {
1769 num_blocks++;
1770 last_block[2] = 0x00;
1771 switch (src_size % 3) {
1772 case 1:
1773 last_block[0] = src[src_size - 1];
1774 last_block[1] = 0x00;
1775 break;
1776 case 2:
1777 last_block[0] = src[src_size - 2];
1778 last_block[1] = src[src_size - 1];
1779 }
1780 }
1781 (*dst_size) = (num_blocks * 4);
1782 if (!dst)
1783 goto out;
1784 while (block_num < num_blocks) {
1785 unsigned char *src_block;
1786 unsigned char dst_block[4];
1787
1788 if (block_num == (num_blocks - 1))
1789 src_block = last_block;
1790 else
1791 src_block = &src[block_num * 3];
1792 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1793 dst_block[1] = (((src_block[0] << 4) & 0x30)
1794 | ((src_block[1] >> 4) & 0x0F));
1795 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1796 | ((src_block[2] >> 6) & 0x03));
1797 dst_block[3] = (src_block[2] & 0x3F);
1798 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1799 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1800 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1801 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1802 block_num++;
1803 }
1804 out:
1805 return;
1806 }
1807
ecryptfs_max_decoded_size(size_t encoded_size)1808 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1809 {
1810 /* Not exact; conservatively long. Every block of 4
1811 * encoded characters decodes into a block of 3
1812 * decoded characters. This segment of code provides
1813 * the caller with the maximum amount of allocated
1814 * space that @dst will need to point to in a
1815 * subsequent call. */
1816 return ((encoded_size + 1) * 3) / 4;
1817 }
1818
1819 /**
1820 * ecryptfs_decode_from_filename
1821 * @dst: If NULL, this function only sets @dst_size and returns. If
1822 * non-NULL, this function decodes the encoded octets in @src
1823 * into the memory that @dst points to.
1824 * @dst_size: Set to the size of the decoded string.
1825 * @src: The encoded set of octets to decode.
1826 * @src_size: The size of the encoded set of octets to decode.
1827 */
1828 static void
ecryptfs_decode_from_filename(unsigned char * dst,size_t * dst_size,const unsigned char * src,size_t src_size)1829 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1830 const unsigned char *src, size_t src_size)
1831 {
1832 u8 current_bit_offset = 0;
1833 size_t src_byte_offset = 0;
1834 size_t dst_byte_offset = 0;
1835
1836 if (!dst) {
1837 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1838 goto out;
1839 }
1840 while (src_byte_offset < src_size) {
1841 unsigned char src_byte =
1842 filename_rev_map[(int)src[src_byte_offset]];
1843
1844 switch (current_bit_offset) {
1845 case 0:
1846 dst[dst_byte_offset] = (src_byte << 2);
1847 current_bit_offset = 6;
1848 break;
1849 case 6:
1850 dst[dst_byte_offset++] |= (src_byte >> 4);
1851 dst[dst_byte_offset] = ((src_byte & 0xF)
1852 << 4);
1853 current_bit_offset = 4;
1854 break;
1855 case 4:
1856 dst[dst_byte_offset++] |= (src_byte >> 2);
1857 dst[dst_byte_offset] = (src_byte << 6);
1858 current_bit_offset = 2;
1859 break;
1860 case 2:
1861 dst[dst_byte_offset++] |= (src_byte);
1862 current_bit_offset = 0;
1863 break;
1864 }
1865 src_byte_offset++;
1866 }
1867 (*dst_size) = dst_byte_offset;
1868 out:
1869 return;
1870 }
1871
1872 /**
1873 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1874 * @encoded_name: The encrypted name
1875 * @encoded_name_size: Length of the encrypted name
1876 * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1877 * @name: The plaintext name
1878 * @name_size: The length of the plaintext name
1879 *
1880 * Encrypts and encodes a filename into something that constitutes a
1881 * valid filename for a filesystem, with printable characters.
1882 *
1883 * We assume that we have a properly initialized crypto context,
1884 * pointed to by crypt_stat->tfm.
1885 *
1886 * Returns zero on success; non-zero on otherwise
1887 */
ecryptfs_encrypt_and_encode_filename(char ** encoded_name,size_t * encoded_name_size,struct ecryptfs_mount_crypt_stat * mount_crypt_stat,const char * name,size_t name_size)1888 int ecryptfs_encrypt_and_encode_filename(
1889 char **encoded_name,
1890 size_t *encoded_name_size,
1891 struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1892 const char *name, size_t name_size)
1893 {
1894 size_t encoded_name_no_prefix_size;
1895 int rc = 0;
1896
1897 (*encoded_name) = NULL;
1898 (*encoded_name_size) = 0;
1899 if (mount_crypt_stat && (mount_crypt_stat->flags
1900 & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1901 struct ecryptfs_filename *filename;
1902
1903 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1904 if (!filename) {
1905 rc = -ENOMEM;
1906 goto out;
1907 }
1908 filename->filename = (char *)name;
1909 filename->filename_size = name_size;
1910 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1911 if (rc) {
1912 printk(KERN_ERR "%s: Error attempting to encrypt "
1913 "filename; rc = [%d]\n", __func__, rc);
1914 kfree(filename);
1915 goto out;
1916 }
1917 ecryptfs_encode_for_filename(
1918 NULL, &encoded_name_no_prefix_size,
1919 filename->encrypted_filename,
1920 filename->encrypted_filename_size);
1921 if (mount_crypt_stat
1922 && (mount_crypt_stat->flags
1923 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1924 (*encoded_name_size) =
1925 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1926 + encoded_name_no_prefix_size);
1927 else
1928 (*encoded_name_size) =
1929 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1930 + encoded_name_no_prefix_size);
1931 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1932 if (!(*encoded_name)) {
1933 rc = -ENOMEM;
1934 kfree(filename->encrypted_filename);
1935 kfree(filename);
1936 goto out;
1937 }
1938 if (mount_crypt_stat
1939 && (mount_crypt_stat->flags
1940 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1941 memcpy((*encoded_name),
1942 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1943 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1944 ecryptfs_encode_for_filename(
1945 ((*encoded_name)
1946 + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1947 &encoded_name_no_prefix_size,
1948 filename->encrypted_filename,
1949 filename->encrypted_filename_size);
1950 (*encoded_name_size) =
1951 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1952 + encoded_name_no_prefix_size);
1953 (*encoded_name)[(*encoded_name_size)] = '\0';
1954 } else {
1955 rc = -EOPNOTSUPP;
1956 }
1957 if (rc) {
1958 printk(KERN_ERR "%s: Error attempting to encode "
1959 "encrypted filename; rc = [%d]\n", __func__,
1960 rc);
1961 kfree((*encoded_name));
1962 (*encoded_name) = NULL;
1963 (*encoded_name_size) = 0;
1964 }
1965 kfree(filename->encrypted_filename);
1966 kfree(filename);
1967 } else {
1968 rc = ecryptfs_copy_filename(encoded_name,
1969 encoded_name_size,
1970 name, name_size);
1971 }
1972 out:
1973 return rc;
1974 }
1975
is_dot_dotdot(const char * name,size_t name_size)1976 static bool is_dot_dotdot(const char *name, size_t name_size)
1977 {
1978 if (name_size == 1 && name[0] == '.')
1979 return true;
1980 else if (name_size == 2 && name[0] == '.' && name[1] == '.')
1981 return true;
1982
1983 return false;
1984 }
1985
1986 /**
1987 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1988 * @plaintext_name: The plaintext name
1989 * @plaintext_name_size: The plaintext name size
1990 * @sb: Ecryptfs's super_block
1991 * @name: The filename in cipher text
1992 * @name_size: The cipher text name size
1993 *
1994 * Decrypts and decodes the filename.
1995 *
1996 * Returns zero on error; non-zero otherwise
1997 */
ecryptfs_decode_and_decrypt_filename(char ** plaintext_name,size_t * plaintext_name_size,struct super_block * sb,const char * name,size_t name_size)1998 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
1999 size_t *plaintext_name_size,
2000 struct super_block *sb,
2001 const char *name, size_t name_size)
2002 {
2003 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2004 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2005 char *decoded_name;
2006 size_t decoded_name_size;
2007 size_t packet_size;
2008 int rc = 0;
2009
2010 if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
2011 !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
2012 if (is_dot_dotdot(name, name_size)) {
2013 rc = ecryptfs_copy_filename(plaintext_name,
2014 plaintext_name_size,
2015 name, name_size);
2016 goto out;
2017 }
2018
2019 if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
2020 strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2021 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
2022 rc = -EINVAL;
2023 goto out;
2024 }
2025
2026 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2027 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2028 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2029 name, name_size);
2030 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2031 if (!decoded_name) {
2032 rc = -ENOMEM;
2033 goto out;
2034 }
2035 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2036 name, name_size);
2037 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2038 plaintext_name_size,
2039 &packet_size,
2040 mount_crypt_stat,
2041 decoded_name,
2042 decoded_name_size);
2043 if (rc) {
2044 ecryptfs_printk(KERN_DEBUG,
2045 "%s: Could not parse tag 70 packet from filename\n",
2046 __func__);
2047 goto out_free;
2048 }
2049 } else {
2050 rc = ecryptfs_copy_filename(plaintext_name,
2051 plaintext_name_size,
2052 name, name_size);
2053 goto out;
2054 }
2055 out_free:
2056 kfree(decoded_name);
2057 out:
2058 return rc;
2059 }
2060
2061 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143
2062
ecryptfs_set_f_namelen(long * namelen,long lower_namelen,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)2063 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2064 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2065 {
2066 struct crypto_skcipher *tfm;
2067 struct mutex *tfm_mutex;
2068 size_t cipher_blocksize;
2069 int rc;
2070
2071 if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2072 (*namelen) = lower_namelen;
2073 return 0;
2074 }
2075
2076 rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2077 mount_crypt_stat->global_default_fn_cipher_name);
2078 if (unlikely(rc)) {
2079 (*namelen) = 0;
2080 return rc;
2081 }
2082
2083 mutex_lock(tfm_mutex);
2084 cipher_blocksize = crypto_skcipher_blocksize(tfm);
2085 mutex_unlock(tfm_mutex);
2086
2087 /* Return an exact amount for the common cases */
2088 if (lower_namelen == NAME_MAX
2089 && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2090 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2091 return 0;
2092 }
2093
2094 /* Return a safe estimate for the uncommon cases */
2095 (*namelen) = lower_namelen;
2096 (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2097 /* Since this is the max decoded size, subtract 1 "decoded block" len */
2098 (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2099 (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2100 (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2101 /* Worst case is that the filename is padded nearly a full block size */
2102 (*namelen) -= cipher_blocksize - 1;
2103
2104 if ((*namelen) < 0)
2105 (*namelen) = 0;
2106
2107 return 0;
2108 }
2109