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 (!crypt_stat || !crypt_stat->tfm
300 || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
301 return -EINVAL;
302
303 if (unlikely(ecryptfs_verbosity > 0)) {
304 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
305 crypt_stat->key_size);
306 ecryptfs_dump_hex(crypt_stat->key,
307 crypt_stat->key_size);
308 }
309
310 init_completion(&ecr.completion);
311
312 mutex_lock(&crypt_stat->cs_tfm_mutex);
313 req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
314 if (!req) {
315 mutex_unlock(&crypt_stat->cs_tfm_mutex);
316 rc = -ENOMEM;
317 goto out;
318 }
319
320 skcipher_request_set_callback(req,
321 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
322 extent_crypt_complete, &ecr);
323 /* Consider doing this once, when the file is opened */
324 if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
325 rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
326 crypt_stat->key_size);
327 if (rc) {
328 ecryptfs_printk(KERN_ERR,
329 "Error setting key; rc = [%d]\n",
330 rc);
331 mutex_unlock(&crypt_stat->cs_tfm_mutex);
332 rc = -EINVAL;
333 goto out;
334 }
335 crypt_stat->flags |= ECRYPTFS_KEY_SET;
336 }
337 mutex_unlock(&crypt_stat->cs_tfm_mutex);
338 skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
339 rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
340 crypto_skcipher_decrypt(req);
341 if (rc == -EINPROGRESS || rc == -EBUSY) {
342 struct extent_crypt_result *ecr = req->base.data;
343
344 wait_for_completion(&ecr->completion);
345 rc = ecr->rc;
346 reinit_completion(&ecr->completion);
347 }
348 out:
349 skcipher_request_free(req);
350 return rc;
351 }
352
353 /*
354 * lower_offset_for_page
355 *
356 * Convert an eCryptfs page index into a lower byte offset
357 */
lower_offset_for_page(struct ecryptfs_crypt_stat * crypt_stat,struct page * page)358 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
359 struct page *page)
360 {
361 return ecryptfs_lower_header_size(crypt_stat) +
362 ((loff_t)page->index << PAGE_SHIFT);
363 }
364
365 /**
366 * crypt_extent
367 * @crypt_stat: crypt_stat containing cryptographic context for the
368 * encryption operation
369 * @dst_page: The page to write the result into
370 * @src_page: The page to read from
371 * @extent_offset: Page extent offset for use in generating IV
372 * @op: ENCRYPT or DECRYPT to indicate the desired operation
373 *
374 * Encrypts or decrypts one extent of data.
375 *
376 * Return zero on success; non-zero otherwise
377 */
crypt_extent(struct ecryptfs_crypt_stat * crypt_stat,struct page * dst_page,struct page * src_page,unsigned long extent_offset,int op)378 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
379 struct page *dst_page,
380 struct page *src_page,
381 unsigned long extent_offset, int op)
382 {
383 pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
384 loff_t extent_base;
385 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
386 struct scatterlist src_sg, dst_sg;
387 size_t extent_size = crypt_stat->extent_size;
388 int rc;
389
390 extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
391 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
392 (extent_base + extent_offset));
393 if (rc) {
394 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
395 "extent [0x%.16llx]; rc = [%d]\n",
396 (unsigned long long)(extent_base + extent_offset), rc);
397 goto out;
398 }
399
400 sg_init_table(&src_sg, 1);
401 sg_init_table(&dst_sg, 1);
402
403 sg_set_page(&src_sg, src_page, extent_size,
404 extent_offset * extent_size);
405 sg_set_page(&dst_sg, dst_page, extent_size,
406 extent_offset * extent_size);
407
408 rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
409 extent_iv, op);
410 if (rc < 0) {
411 printk(KERN_ERR "%s: Error attempting to crypt page with "
412 "page_index = [%ld], extent_offset = [%ld]; "
413 "rc = [%d]\n", __func__, page_index, extent_offset, rc);
414 goto out;
415 }
416 rc = 0;
417 out:
418 return rc;
419 }
420
421 /**
422 * ecryptfs_encrypt_page
423 * @page: Page mapped from the eCryptfs inode for the file; contains
424 * decrypted content that needs to be encrypted (to a temporary
425 * page; not in place) and written out to the lower file
426 *
427 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
428 * that eCryptfs pages may straddle the lower pages -- for instance,
429 * if the file was created on a machine with an 8K page size
430 * (resulting in an 8K header), and then the file is copied onto a
431 * host with a 32K page size, then when reading page 0 of the eCryptfs
432 * file, 24K of page 0 of the lower file will be read and decrypted,
433 * and then 8K of page 1 of the lower file will be read and decrypted.
434 *
435 * Returns zero on success; negative on error
436 */
ecryptfs_encrypt_page(struct page * page)437 int ecryptfs_encrypt_page(struct page *page)
438 {
439 struct inode *ecryptfs_inode;
440 struct ecryptfs_crypt_stat *crypt_stat;
441 char *enc_extent_virt;
442 struct page *enc_extent_page = NULL;
443 loff_t extent_offset;
444 loff_t lower_offset;
445 int rc = 0;
446
447 ecryptfs_inode = page->mapping->host;
448 crypt_stat =
449 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
450 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
451 enc_extent_page = alloc_page(GFP_USER);
452 if (!enc_extent_page) {
453 rc = -ENOMEM;
454 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
455 "encrypted extent\n");
456 goto out;
457 }
458
459 for (extent_offset = 0;
460 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
461 extent_offset++) {
462 rc = crypt_extent(crypt_stat, enc_extent_page, page,
463 extent_offset, ENCRYPT);
464 if (rc) {
465 printk(KERN_ERR "%s: Error encrypting extent; "
466 "rc = [%d]\n", __func__, rc);
467 goto out;
468 }
469 }
470
471 lower_offset = lower_offset_for_page(crypt_stat, page);
472 enc_extent_virt = kmap(enc_extent_page);
473 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
474 PAGE_SIZE);
475 kunmap(enc_extent_page);
476 if (rc < 0) {
477 ecryptfs_printk(KERN_ERR,
478 "Error attempting to write lower page; rc = [%d]\n",
479 rc);
480 goto out;
481 }
482 rc = 0;
483 out:
484 if (enc_extent_page) {
485 __free_page(enc_extent_page);
486 }
487 return rc;
488 }
489
490 /**
491 * ecryptfs_decrypt_page
492 * @page: Page mapped from the eCryptfs inode for the file; data read
493 * and decrypted from the lower file will be written into this
494 * page
495 *
496 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
497 * that eCryptfs pages may straddle the lower pages -- for instance,
498 * if the file was created on a machine with an 8K page size
499 * (resulting in an 8K header), and then the file is copied onto a
500 * host with a 32K page size, then when reading page 0 of the eCryptfs
501 * file, 24K of page 0 of the lower file will be read and decrypted,
502 * and then 8K of page 1 of the lower file will be read and decrypted.
503 *
504 * Returns zero on success; negative on error
505 */
ecryptfs_decrypt_page(struct page * page)506 int ecryptfs_decrypt_page(struct page *page)
507 {
508 struct inode *ecryptfs_inode;
509 struct ecryptfs_crypt_stat *crypt_stat;
510 char *page_virt;
511 unsigned long extent_offset;
512 loff_t lower_offset;
513 int rc = 0;
514
515 ecryptfs_inode = page->mapping->host;
516 crypt_stat =
517 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
518 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
519
520 lower_offset = lower_offset_for_page(crypt_stat, page);
521 page_virt = kmap(page);
522 rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
523 ecryptfs_inode);
524 kunmap(page);
525 if (rc < 0) {
526 ecryptfs_printk(KERN_ERR,
527 "Error attempting to read lower page; rc = [%d]\n",
528 rc);
529 goto out;
530 }
531
532 for (extent_offset = 0;
533 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
534 extent_offset++) {
535 rc = crypt_extent(crypt_stat, page, page,
536 extent_offset, DECRYPT);
537 if (rc) {
538 printk(KERN_ERR "%s: Error decrypting extent; "
539 "rc = [%d]\n", __func__, rc);
540 goto out;
541 }
542 }
543 out:
544 return rc;
545 }
546
547 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
548
549 /**
550 * ecryptfs_init_crypt_ctx
551 * @crypt_stat: Uninitialized crypt stats structure
552 *
553 * Initialize the crypto context.
554 *
555 * TODO: Performance: Keep a cache of initialized cipher contexts;
556 * only init if needed
557 */
ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat * crypt_stat)558 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
559 {
560 char *full_alg_name;
561 int rc = -EINVAL;
562
563 ecryptfs_printk(KERN_DEBUG,
564 "Initializing cipher [%s]; strlen = [%d]; "
565 "key_size_bits = [%zd]\n",
566 crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
567 crypt_stat->key_size << 3);
568 mutex_lock(&crypt_stat->cs_tfm_mutex);
569 if (crypt_stat->tfm) {
570 rc = 0;
571 goto out_unlock;
572 }
573 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
574 crypt_stat->cipher, "cbc");
575 if (rc)
576 goto out_unlock;
577 crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
578 if (IS_ERR(crypt_stat->tfm)) {
579 rc = PTR_ERR(crypt_stat->tfm);
580 crypt_stat->tfm = NULL;
581 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
582 "Error initializing cipher [%s]\n",
583 full_alg_name);
584 goto out_free;
585 }
586 crypto_skcipher_set_flags(crypt_stat->tfm,
587 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
588 rc = 0;
589 out_free:
590 kfree(full_alg_name);
591 out_unlock:
592 mutex_unlock(&crypt_stat->cs_tfm_mutex);
593 return rc;
594 }
595
set_extent_mask_and_shift(struct ecryptfs_crypt_stat * crypt_stat)596 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
597 {
598 int extent_size_tmp;
599
600 crypt_stat->extent_mask = 0xFFFFFFFF;
601 crypt_stat->extent_shift = 0;
602 if (crypt_stat->extent_size == 0)
603 return;
604 extent_size_tmp = crypt_stat->extent_size;
605 while ((extent_size_tmp & 0x01) == 0) {
606 extent_size_tmp >>= 1;
607 crypt_stat->extent_mask <<= 1;
608 crypt_stat->extent_shift++;
609 }
610 }
611
ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat * crypt_stat)612 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
613 {
614 /* Default values; may be overwritten as we are parsing the
615 * packets. */
616 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
617 set_extent_mask_and_shift(crypt_stat);
618 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
619 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
620 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
621 else {
622 if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
623 crypt_stat->metadata_size =
624 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
625 else
626 crypt_stat->metadata_size = PAGE_SIZE;
627 }
628 }
629
630 /*
631 * ecryptfs_compute_root_iv
632 *
633 * On error, sets the root IV to all 0's.
634 */
ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat * crypt_stat)635 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
636 {
637 int rc = 0;
638 char dst[MD5_DIGEST_SIZE];
639
640 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
641 BUG_ON(crypt_stat->iv_bytes <= 0);
642 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
643 rc = -EINVAL;
644 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
645 "cannot generate root IV\n");
646 goto out;
647 }
648 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
649 crypt_stat->key_size);
650 if (rc) {
651 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
652 "MD5 while generating root IV\n");
653 goto out;
654 }
655 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
656 out:
657 if (rc) {
658 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
659 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
660 }
661 return rc;
662 }
663
ecryptfs_generate_new_key(struct ecryptfs_crypt_stat * crypt_stat)664 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
665 {
666 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
667 crypt_stat->flags |= ECRYPTFS_KEY_VALID;
668 ecryptfs_compute_root_iv(crypt_stat);
669 if (unlikely(ecryptfs_verbosity > 0)) {
670 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
671 ecryptfs_dump_hex(crypt_stat->key,
672 crypt_stat->key_size);
673 }
674 }
675
676 /**
677 * ecryptfs_copy_mount_wide_flags_to_inode_flags
678 * @crypt_stat: The inode's cryptographic context
679 * @mount_crypt_stat: The mount point's cryptographic context
680 *
681 * This function propagates the mount-wide flags to individual inode
682 * flags.
683 */
ecryptfs_copy_mount_wide_flags_to_inode_flags(struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)684 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
685 struct ecryptfs_crypt_stat *crypt_stat,
686 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
687 {
688 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
689 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
690 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
691 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
692 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
693 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
694 if (mount_crypt_stat->flags
695 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
696 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
697 else if (mount_crypt_stat->flags
698 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
699 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
700 }
701 }
702
ecryptfs_copy_mount_wide_sigs_to_inode_sigs(struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)703 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
704 struct ecryptfs_crypt_stat *crypt_stat,
705 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
706 {
707 struct ecryptfs_global_auth_tok *global_auth_tok;
708 int rc = 0;
709
710 mutex_lock(&crypt_stat->keysig_list_mutex);
711 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
712
713 list_for_each_entry(global_auth_tok,
714 &mount_crypt_stat->global_auth_tok_list,
715 mount_crypt_stat_list) {
716 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
717 continue;
718 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
719 if (rc) {
720 printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
721 goto out;
722 }
723 }
724
725 out:
726 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
727 mutex_unlock(&crypt_stat->keysig_list_mutex);
728 return rc;
729 }
730
731 /**
732 * ecryptfs_set_default_crypt_stat_vals
733 * @crypt_stat: The inode's cryptographic context
734 * @mount_crypt_stat: The mount point's cryptographic context
735 *
736 * Default values in the event that policy does not override them.
737 */
ecryptfs_set_default_crypt_stat_vals(struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)738 static void ecryptfs_set_default_crypt_stat_vals(
739 struct ecryptfs_crypt_stat *crypt_stat,
740 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
741 {
742 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
743 mount_crypt_stat);
744 ecryptfs_set_default_sizes(crypt_stat);
745 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
746 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
747 crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
748 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
749 crypt_stat->mount_crypt_stat = mount_crypt_stat;
750 }
751
752 /**
753 * ecryptfs_new_file_context
754 * @ecryptfs_inode: The eCryptfs inode
755 *
756 * If the crypto context for the file has not yet been established,
757 * this is where we do that. Establishing a new crypto context
758 * involves the following decisions:
759 * - What cipher to use?
760 * - What set of authentication tokens to use?
761 * Here we just worry about getting enough information into the
762 * authentication tokens so that we know that they are available.
763 * We associate the available authentication tokens with the new file
764 * via the set of signatures in the crypt_stat struct. Later, when
765 * the headers are actually written out, we may again defer to
766 * userspace to perform the encryption of the session key; for the
767 * foreseeable future, this will be the case with public key packets.
768 *
769 * Returns zero on success; non-zero otherwise
770 */
ecryptfs_new_file_context(struct inode * ecryptfs_inode)771 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
772 {
773 struct ecryptfs_crypt_stat *crypt_stat =
774 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
775 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
776 &ecryptfs_superblock_to_private(
777 ecryptfs_inode->i_sb)->mount_crypt_stat;
778 int cipher_name_len;
779 int rc = 0;
780
781 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
782 crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
783 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
784 mount_crypt_stat);
785 rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
786 mount_crypt_stat);
787 if (rc) {
788 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
789 "to the inode key sigs; rc = [%d]\n", rc);
790 goto out;
791 }
792 cipher_name_len =
793 strlen(mount_crypt_stat->global_default_cipher_name);
794 memcpy(crypt_stat->cipher,
795 mount_crypt_stat->global_default_cipher_name,
796 cipher_name_len);
797 crypt_stat->cipher[cipher_name_len] = '\0';
798 crypt_stat->key_size =
799 mount_crypt_stat->global_default_cipher_key_size;
800 ecryptfs_generate_new_key(crypt_stat);
801 rc = ecryptfs_init_crypt_ctx(crypt_stat);
802 if (rc)
803 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
804 "context for cipher [%s]: rc = [%d]\n",
805 crypt_stat->cipher, rc);
806 out:
807 return rc;
808 }
809
810 /**
811 * ecryptfs_validate_marker - check for the ecryptfs marker
812 * @data: The data block in which to check
813 *
814 * Returns zero if marker found; -EINVAL if not found
815 */
ecryptfs_validate_marker(char * data)816 static int ecryptfs_validate_marker(char *data)
817 {
818 u32 m_1, m_2;
819
820 m_1 = get_unaligned_be32(data);
821 m_2 = get_unaligned_be32(data + 4);
822 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
823 return 0;
824 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
825 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
826 MAGIC_ECRYPTFS_MARKER);
827 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
828 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
829 return -EINVAL;
830 }
831
832 struct ecryptfs_flag_map_elem {
833 u32 file_flag;
834 u32 local_flag;
835 };
836
837 /* Add support for additional flags by adding elements here. */
838 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
839 {0x00000001, ECRYPTFS_ENABLE_HMAC},
840 {0x00000002, ECRYPTFS_ENCRYPTED},
841 {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
842 {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
843 };
844
845 /**
846 * ecryptfs_process_flags
847 * @crypt_stat: The cryptographic context
848 * @page_virt: Source data to be parsed
849 * @bytes_read: Updated with the number of bytes read
850 */
ecryptfs_process_flags(struct ecryptfs_crypt_stat * crypt_stat,char * page_virt,int * bytes_read)851 static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
852 char *page_virt, int *bytes_read)
853 {
854 int i;
855 u32 flags;
856
857 flags = get_unaligned_be32(page_virt);
858 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
859 if (flags & ecryptfs_flag_map[i].file_flag) {
860 crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
861 } else
862 crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
863 /* Version is in top 8 bits of the 32-bit flag vector */
864 crypt_stat->file_version = ((flags >> 24) & 0xFF);
865 (*bytes_read) = 4;
866 }
867
868 /**
869 * write_ecryptfs_marker
870 * @page_virt: The pointer to in a page to begin writing the marker
871 * @written: Number of bytes written
872 *
873 * Marker = 0x3c81b7f5
874 */
write_ecryptfs_marker(char * page_virt,size_t * written)875 static void write_ecryptfs_marker(char *page_virt, size_t *written)
876 {
877 u32 m_1, m_2;
878
879 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
880 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
881 put_unaligned_be32(m_1, page_virt);
882 page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
883 put_unaligned_be32(m_2, page_virt);
884 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
885 }
886
ecryptfs_write_crypt_stat_flags(char * page_virt,struct ecryptfs_crypt_stat * crypt_stat,size_t * written)887 void ecryptfs_write_crypt_stat_flags(char *page_virt,
888 struct ecryptfs_crypt_stat *crypt_stat,
889 size_t *written)
890 {
891 u32 flags = 0;
892 int i;
893
894 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
895 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
896 flags |= ecryptfs_flag_map[i].file_flag;
897 /* Version is in top 8 bits of the 32-bit flag vector */
898 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
899 put_unaligned_be32(flags, page_virt);
900 (*written) = 4;
901 }
902
903 struct ecryptfs_cipher_code_str_map_elem {
904 char cipher_str[16];
905 u8 cipher_code;
906 };
907
908 /* Add support for additional ciphers by adding elements here. The
909 * cipher_code is whatever OpenPGP applications use to identify the
910 * ciphers. List in order of probability. */
911 static struct ecryptfs_cipher_code_str_map_elem
912 ecryptfs_cipher_code_str_map[] = {
913 {"aes",RFC2440_CIPHER_AES_128 },
914 {"blowfish", RFC2440_CIPHER_BLOWFISH},
915 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
916 {"cast5", RFC2440_CIPHER_CAST_5},
917 {"twofish", RFC2440_CIPHER_TWOFISH},
918 {"cast6", RFC2440_CIPHER_CAST_6},
919 {"aes", RFC2440_CIPHER_AES_192},
920 {"aes", RFC2440_CIPHER_AES_256}
921 };
922
923 /**
924 * ecryptfs_code_for_cipher_string
925 * @cipher_name: The string alias for the cipher
926 * @key_bytes: Length of key in bytes; used for AES code selection
927 *
928 * Returns zero on no match, or the cipher code on match
929 */
ecryptfs_code_for_cipher_string(char * cipher_name,size_t key_bytes)930 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
931 {
932 int i;
933 u8 code = 0;
934 struct ecryptfs_cipher_code_str_map_elem *map =
935 ecryptfs_cipher_code_str_map;
936
937 if (strcmp(cipher_name, "aes") == 0) {
938 switch (key_bytes) {
939 case 16:
940 code = RFC2440_CIPHER_AES_128;
941 break;
942 case 24:
943 code = RFC2440_CIPHER_AES_192;
944 break;
945 case 32:
946 code = RFC2440_CIPHER_AES_256;
947 }
948 } else {
949 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
950 if (strcmp(cipher_name, map[i].cipher_str) == 0) {
951 code = map[i].cipher_code;
952 break;
953 }
954 }
955 return code;
956 }
957
958 /**
959 * ecryptfs_cipher_code_to_string
960 * @str: Destination to write out the cipher name
961 * @cipher_code: The code to convert to cipher name string
962 *
963 * Returns zero on success
964 */
ecryptfs_cipher_code_to_string(char * str,u8 cipher_code)965 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
966 {
967 int rc = 0;
968 int i;
969
970 str[0] = '\0';
971 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
972 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
973 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
974 if (str[0] == '\0') {
975 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
976 "[%d]\n", cipher_code);
977 rc = -EINVAL;
978 }
979 return rc;
980 }
981
ecryptfs_read_and_validate_header_region(struct inode * inode)982 int ecryptfs_read_and_validate_header_region(struct inode *inode)
983 {
984 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
985 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
986 int rc;
987
988 rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
989 inode);
990 if (rc < 0)
991 return rc;
992 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
993 return -EINVAL;
994 rc = ecryptfs_validate_marker(marker);
995 if (!rc)
996 ecryptfs_i_size_init(file_size, inode);
997 return rc;
998 }
999
1000 void
ecryptfs_write_header_metadata(char * virt,struct ecryptfs_crypt_stat * crypt_stat,size_t * written)1001 ecryptfs_write_header_metadata(char *virt,
1002 struct ecryptfs_crypt_stat *crypt_stat,
1003 size_t *written)
1004 {
1005 u32 header_extent_size;
1006 u16 num_header_extents_at_front;
1007
1008 header_extent_size = (u32)crypt_stat->extent_size;
1009 num_header_extents_at_front =
1010 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1011 put_unaligned_be32(header_extent_size, virt);
1012 virt += 4;
1013 put_unaligned_be16(num_header_extents_at_front, virt);
1014 (*written) = 6;
1015 }
1016
1017 struct kmem_cache *ecryptfs_header_cache;
1018
1019 /**
1020 * ecryptfs_write_headers_virt
1021 * @page_virt: The virtual address to write the headers to
1022 * @max: The size of memory allocated at page_virt
1023 * @size: Set to the number of bytes written by this function
1024 * @crypt_stat: The cryptographic context
1025 * @ecryptfs_dentry: The eCryptfs dentry
1026 *
1027 * Format version: 1
1028 *
1029 * Header Extent:
1030 * Octets 0-7: Unencrypted file size (big-endian)
1031 * Octets 8-15: eCryptfs special marker
1032 * Octets 16-19: Flags
1033 * Octet 16: File format version number (between 0 and 255)
1034 * Octets 17-18: Reserved
1035 * Octet 19: Bit 1 (lsb): Reserved
1036 * Bit 2: Encrypted?
1037 * Bits 3-8: Reserved
1038 * Octets 20-23: Header extent size (big-endian)
1039 * Octets 24-25: Number of header extents at front of file
1040 * (big-endian)
1041 * Octet 26: Begin RFC 2440 authentication token packet set
1042 * Data Extent 0:
1043 * Lower data (CBC encrypted)
1044 * Data Extent 1:
1045 * Lower data (CBC encrypted)
1046 * ...
1047 *
1048 * Returns zero on success
1049 */
ecryptfs_write_headers_virt(char * page_virt,size_t max,size_t * size,struct ecryptfs_crypt_stat * crypt_stat,struct dentry * ecryptfs_dentry)1050 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1051 size_t *size,
1052 struct ecryptfs_crypt_stat *crypt_stat,
1053 struct dentry *ecryptfs_dentry)
1054 {
1055 int rc;
1056 size_t written;
1057 size_t offset;
1058
1059 offset = ECRYPTFS_FILE_SIZE_BYTES;
1060 write_ecryptfs_marker((page_virt + offset), &written);
1061 offset += written;
1062 ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1063 &written);
1064 offset += written;
1065 ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1066 &written);
1067 offset += written;
1068 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1069 ecryptfs_dentry, &written,
1070 max - offset);
1071 if (rc)
1072 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1073 "set; rc = [%d]\n", rc);
1074 if (size) {
1075 offset += written;
1076 *size = offset;
1077 }
1078 return rc;
1079 }
1080
1081 static int
ecryptfs_write_metadata_to_contents(struct inode * ecryptfs_inode,char * virt,size_t virt_len)1082 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1083 char *virt, size_t virt_len)
1084 {
1085 int rc;
1086
1087 rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1088 0, virt_len);
1089 if (rc < 0)
1090 printk(KERN_ERR "%s: Error attempting to write header "
1091 "information to lower file; rc = [%d]\n", __func__, rc);
1092 else
1093 rc = 0;
1094 return rc;
1095 }
1096
1097 static int
ecryptfs_write_metadata_to_xattr(struct dentry * ecryptfs_dentry,struct inode * ecryptfs_inode,char * page_virt,size_t size)1098 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1099 struct inode *ecryptfs_inode,
1100 char *page_virt, size_t size)
1101 {
1102 int rc;
1103 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
1104 struct inode *lower_inode = d_inode(lower_dentry);
1105
1106 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1107 rc = -EOPNOTSUPP;
1108 goto out;
1109 }
1110
1111 inode_lock(lower_inode);
1112 rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode,
1113 ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1114 if (!rc && ecryptfs_inode)
1115 fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
1116 inode_unlock(lower_inode);
1117 out:
1118 return rc;
1119 }
1120
ecryptfs_get_zeroed_pages(gfp_t gfp_mask,unsigned int order)1121 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1122 unsigned int order)
1123 {
1124 struct page *page;
1125
1126 page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1127 if (page)
1128 return (unsigned long) page_address(page);
1129 return 0;
1130 }
1131
1132 /**
1133 * ecryptfs_write_metadata
1134 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1135 * @ecryptfs_inode: The newly created eCryptfs inode
1136 *
1137 * Write the file headers out. This will likely involve a userspace
1138 * callout, in which the session key is encrypted with one or more
1139 * public keys and/or the passphrase necessary to do the encryption is
1140 * retrieved via a prompt. Exactly what happens at this point should
1141 * be policy-dependent.
1142 *
1143 * Returns zero on success; non-zero on error
1144 */
ecryptfs_write_metadata(struct dentry * ecryptfs_dentry,struct inode * ecryptfs_inode)1145 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1146 struct inode *ecryptfs_inode)
1147 {
1148 struct ecryptfs_crypt_stat *crypt_stat =
1149 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1150 unsigned int order;
1151 char *virt;
1152 size_t virt_len;
1153 size_t size = 0;
1154 int rc = 0;
1155
1156 if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1157 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1158 printk(KERN_ERR "Key is invalid; bailing out\n");
1159 rc = -EINVAL;
1160 goto out;
1161 }
1162 } else {
1163 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1164 __func__);
1165 rc = -EINVAL;
1166 goto out;
1167 }
1168 virt_len = crypt_stat->metadata_size;
1169 order = get_order(virt_len);
1170 /* Released in this function */
1171 virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1172 if (!virt) {
1173 printk(KERN_ERR "%s: Out of memory\n", __func__);
1174 rc = -ENOMEM;
1175 goto out;
1176 }
1177 /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1178 rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1179 ecryptfs_dentry);
1180 if (unlikely(rc)) {
1181 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1182 __func__, rc);
1183 goto out_free;
1184 }
1185 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1186 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1187 virt, size);
1188 else
1189 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1190 virt_len);
1191 if (rc) {
1192 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1193 "rc = [%d]\n", __func__, rc);
1194 goto out_free;
1195 }
1196 out_free:
1197 free_pages((unsigned long)virt, order);
1198 out:
1199 return rc;
1200 }
1201
1202 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1203 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
parse_header_metadata(struct ecryptfs_crypt_stat * crypt_stat,char * virt,int * bytes_read,int validate_header_size)1204 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1205 char *virt, int *bytes_read,
1206 int validate_header_size)
1207 {
1208 int rc = 0;
1209 u32 header_extent_size;
1210 u16 num_header_extents_at_front;
1211
1212 header_extent_size = get_unaligned_be32(virt);
1213 virt += sizeof(__be32);
1214 num_header_extents_at_front = get_unaligned_be16(virt);
1215 crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1216 * (size_t)header_extent_size));
1217 (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1218 if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1219 && (crypt_stat->metadata_size
1220 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1221 rc = -EINVAL;
1222 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1223 crypt_stat->metadata_size);
1224 }
1225 return rc;
1226 }
1227
1228 /**
1229 * set_default_header_data
1230 * @crypt_stat: The cryptographic context
1231 *
1232 * For version 0 file format; this function is only for backwards
1233 * compatibility for files created with the prior versions of
1234 * eCryptfs.
1235 */
set_default_header_data(struct ecryptfs_crypt_stat * crypt_stat)1236 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1237 {
1238 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1239 }
1240
ecryptfs_i_size_init(const char * page_virt,struct inode * inode)1241 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1242 {
1243 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1244 struct ecryptfs_crypt_stat *crypt_stat;
1245 u64 file_size;
1246
1247 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1248 mount_crypt_stat =
1249 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1250 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1251 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1252 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1253 file_size += crypt_stat->metadata_size;
1254 } else
1255 file_size = get_unaligned_be64(page_virt);
1256 i_size_write(inode, (loff_t)file_size);
1257 crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1258 }
1259
1260 /**
1261 * ecryptfs_read_headers_virt
1262 * @page_virt: The virtual address into which to read the headers
1263 * @crypt_stat: The cryptographic context
1264 * @ecryptfs_dentry: The eCryptfs dentry
1265 * @validate_header_size: Whether to validate the header size while reading
1266 *
1267 * Read/parse the header data. The header format is detailed in the
1268 * comment block for the ecryptfs_write_headers_virt() function.
1269 *
1270 * Returns zero on success
1271 */
ecryptfs_read_headers_virt(char * page_virt,struct ecryptfs_crypt_stat * crypt_stat,struct dentry * ecryptfs_dentry,int validate_header_size)1272 static int ecryptfs_read_headers_virt(char *page_virt,
1273 struct ecryptfs_crypt_stat *crypt_stat,
1274 struct dentry *ecryptfs_dentry,
1275 int validate_header_size)
1276 {
1277 int rc = 0;
1278 int offset;
1279 int bytes_read;
1280
1281 ecryptfs_set_default_sizes(crypt_stat);
1282 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1283 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1284 offset = ECRYPTFS_FILE_SIZE_BYTES;
1285 rc = ecryptfs_validate_marker(page_virt + offset);
1286 if (rc)
1287 goto out;
1288 if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1289 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1290 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1291 ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
1292 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1293 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1294 "file version [%d] is supported by this "
1295 "version of eCryptfs\n",
1296 crypt_stat->file_version,
1297 ECRYPTFS_SUPPORTED_FILE_VERSION);
1298 rc = -EINVAL;
1299 goto out;
1300 }
1301 offset += bytes_read;
1302 if (crypt_stat->file_version >= 1) {
1303 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1304 &bytes_read, validate_header_size);
1305 if (rc) {
1306 ecryptfs_printk(KERN_WARNING, "Error reading header "
1307 "metadata; rc = [%d]\n", rc);
1308 }
1309 offset += bytes_read;
1310 } else
1311 set_default_header_data(crypt_stat);
1312 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1313 ecryptfs_dentry);
1314 out:
1315 return rc;
1316 }
1317
1318 /**
1319 * ecryptfs_read_xattr_region
1320 * @page_virt: The vitual address into which to read the xattr data
1321 * @ecryptfs_inode: The eCryptfs inode
1322 *
1323 * Attempts to read the crypto metadata from the extended attribute
1324 * region of the lower file.
1325 *
1326 * Returns zero on success; non-zero on error
1327 */
ecryptfs_read_xattr_region(char * page_virt,struct inode * ecryptfs_inode)1328 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1329 {
1330 struct dentry *lower_dentry =
1331 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1332 ssize_t size;
1333 int rc = 0;
1334
1335 size = ecryptfs_getxattr_lower(lower_dentry,
1336 ecryptfs_inode_to_lower(ecryptfs_inode),
1337 ECRYPTFS_XATTR_NAME,
1338 page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1339 if (size < 0) {
1340 if (unlikely(ecryptfs_verbosity > 0))
1341 printk(KERN_INFO "Error attempting to read the [%s] "
1342 "xattr from the lower file; return value = "
1343 "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1344 rc = -EINVAL;
1345 goto out;
1346 }
1347 out:
1348 return rc;
1349 }
1350
ecryptfs_read_and_validate_xattr_region(struct dentry * dentry,struct inode * inode)1351 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1352 struct inode *inode)
1353 {
1354 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1355 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1356 int rc;
1357
1358 rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1359 ecryptfs_inode_to_lower(inode),
1360 ECRYPTFS_XATTR_NAME, file_size,
1361 ECRYPTFS_SIZE_AND_MARKER_BYTES);
1362 if (rc < 0)
1363 return rc;
1364 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1365 return -EINVAL;
1366 rc = ecryptfs_validate_marker(marker);
1367 if (!rc)
1368 ecryptfs_i_size_init(file_size, inode);
1369 return rc;
1370 }
1371
1372 /*
1373 * ecryptfs_read_metadata
1374 *
1375 * Common entry point for reading file metadata. From here, we could
1376 * retrieve the header information from the header region of the file,
1377 * the xattr region of the file, or some other repository that is
1378 * stored separately from the file itself. The current implementation
1379 * supports retrieving the metadata information from the file contents
1380 * and from the xattr region.
1381 *
1382 * Returns zero if valid headers found and parsed; non-zero otherwise
1383 */
ecryptfs_read_metadata(struct dentry * ecryptfs_dentry)1384 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1385 {
1386 int rc;
1387 char *page_virt;
1388 struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1389 struct ecryptfs_crypt_stat *crypt_stat =
1390 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1391 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1392 &ecryptfs_superblock_to_private(
1393 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1394
1395 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1396 mount_crypt_stat);
1397 /* Read the first page from the underlying file */
1398 page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1399 if (!page_virt) {
1400 rc = -ENOMEM;
1401 goto out;
1402 }
1403 rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1404 ecryptfs_inode);
1405 if (rc >= 0)
1406 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1407 ecryptfs_dentry,
1408 ECRYPTFS_VALIDATE_HEADER_SIZE);
1409 if (rc) {
1410 /* metadata is not in the file header, so try xattrs */
1411 memset(page_virt, 0, PAGE_SIZE);
1412 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1413 if (rc) {
1414 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1415 "file header region or xattr region, inode %lu\n",
1416 ecryptfs_inode->i_ino);
1417 rc = -EINVAL;
1418 goto out;
1419 }
1420 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1421 ecryptfs_dentry,
1422 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1423 if (rc) {
1424 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1425 "file xattr region either, inode %lu\n",
1426 ecryptfs_inode->i_ino);
1427 rc = -EINVAL;
1428 }
1429 if (crypt_stat->mount_crypt_stat->flags
1430 & ECRYPTFS_XATTR_METADATA_ENABLED) {
1431 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1432 } else {
1433 printk(KERN_WARNING "Attempt to access file with "
1434 "crypto metadata only in the extended attribute "
1435 "region, but eCryptfs was mounted without "
1436 "xattr support enabled. eCryptfs will not treat "
1437 "this like an encrypted file, inode %lu\n",
1438 ecryptfs_inode->i_ino);
1439 rc = -EINVAL;
1440 }
1441 }
1442 out:
1443 if (page_virt) {
1444 memset(page_virt, 0, PAGE_SIZE);
1445 kmem_cache_free(ecryptfs_header_cache, page_virt);
1446 }
1447 return rc;
1448 }
1449
1450 /*
1451 * ecryptfs_encrypt_filename - encrypt filename
1452 *
1453 * CBC-encrypts the filename. We do not want to encrypt the same
1454 * filename with the same key and IV, which may happen with hard
1455 * links, so we prepend random bits to each filename.
1456 *
1457 * Returns zero on success; non-zero otherwise
1458 */
1459 static int
ecryptfs_encrypt_filename(struct ecryptfs_filename * filename,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)1460 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1461 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1462 {
1463 int rc = 0;
1464
1465 filename->encrypted_filename = NULL;
1466 filename->encrypted_filename_size = 0;
1467 if (mount_crypt_stat && (mount_crypt_stat->flags
1468 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1469 size_t packet_size;
1470 size_t remaining_bytes;
1471
1472 rc = ecryptfs_write_tag_70_packet(
1473 NULL, NULL,
1474 &filename->encrypted_filename_size,
1475 mount_crypt_stat, NULL,
1476 filename->filename_size);
1477 if (rc) {
1478 printk(KERN_ERR "%s: Error attempting to get packet "
1479 "size for tag 72; rc = [%d]\n", __func__,
1480 rc);
1481 filename->encrypted_filename_size = 0;
1482 goto out;
1483 }
1484 filename->encrypted_filename =
1485 kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1486 if (!filename->encrypted_filename) {
1487 rc = -ENOMEM;
1488 goto out;
1489 }
1490 remaining_bytes = filename->encrypted_filename_size;
1491 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1492 &remaining_bytes,
1493 &packet_size,
1494 mount_crypt_stat,
1495 filename->filename,
1496 filename->filename_size);
1497 if (rc) {
1498 printk(KERN_ERR "%s: Error attempting to generate "
1499 "tag 70 packet; rc = [%d]\n", __func__,
1500 rc);
1501 kfree(filename->encrypted_filename);
1502 filename->encrypted_filename = NULL;
1503 filename->encrypted_filename_size = 0;
1504 goto out;
1505 }
1506 filename->encrypted_filename_size = packet_size;
1507 } else {
1508 printk(KERN_ERR "%s: No support for requested filename "
1509 "encryption method in this release\n", __func__);
1510 rc = -EOPNOTSUPP;
1511 goto out;
1512 }
1513 out:
1514 return rc;
1515 }
1516
ecryptfs_copy_filename(char ** copied_name,size_t * copied_name_size,const char * name,size_t name_size)1517 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1518 const char *name, size_t name_size)
1519 {
1520 int rc = 0;
1521
1522 (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1523 if (!(*copied_name)) {
1524 rc = -ENOMEM;
1525 goto out;
1526 }
1527 memcpy((void *)(*copied_name), (void *)name, name_size);
1528 (*copied_name)[(name_size)] = '\0'; /* Only for convenience
1529 * in printing out the
1530 * string in debug
1531 * messages */
1532 (*copied_name_size) = name_size;
1533 out:
1534 return rc;
1535 }
1536
1537 /**
1538 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1539 * @key_tfm: Crypto context for key material, set by this function
1540 * @cipher_name: Name of the cipher
1541 * @key_size: Size of the key in bytes
1542 *
1543 * Returns zero on success. Any crypto_tfm structs allocated here
1544 * should be released by other functions, such as on a superblock put
1545 * event, regardless of whether this function succeeds for fails.
1546 */
1547 static int
ecryptfs_process_key_cipher(struct crypto_skcipher ** key_tfm,char * cipher_name,size_t * key_size)1548 ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1549 char *cipher_name, size_t *key_size)
1550 {
1551 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1552 char *full_alg_name = NULL;
1553 int rc;
1554
1555 *key_tfm = NULL;
1556 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1557 rc = -EINVAL;
1558 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1559 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1560 goto out;
1561 }
1562 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1563 "ecb");
1564 if (rc)
1565 goto out;
1566 *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1567 if (IS_ERR(*key_tfm)) {
1568 rc = PTR_ERR(*key_tfm);
1569 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1570 "[%s]; rc = [%d]\n", full_alg_name, rc);
1571 goto out;
1572 }
1573 crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1574 if (*key_size == 0)
1575 *key_size = crypto_skcipher_max_keysize(*key_tfm);
1576 get_random_bytes(dummy_key, *key_size);
1577 rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1578 if (rc) {
1579 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1580 "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1581 rc);
1582 rc = -EINVAL;
1583 goto out;
1584 }
1585 out:
1586 kfree(full_alg_name);
1587 return rc;
1588 }
1589
1590 struct kmem_cache *ecryptfs_key_tfm_cache;
1591 static struct list_head key_tfm_list;
1592 DEFINE_MUTEX(key_tfm_list_mutex);
1593
ecryptfs_init_crypto(void)1594 int __init ecryptfs_init_crypto(void)
1595 {
1596 INIT_LIST_HEAD(&key_tfm_list);
1597 return 0;
1598 }
1599
1600 /**
1601 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1602 *
1603 * Called only at module unload time
1604 */
ecryptfs_destroy_crypto(void)1605 int ecryptfs_destroy_crypto(void)
1606 {
1607 struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1608
1609 mutex_lock(&key_tfm_list_mutex);
1610 list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1611 key_tfm_list) {
1612 list_del(&key_tfm->key_tfm_list);
1613 crypto_free_skcipher(key_tfm->key_tfm);
1614 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1615 }
1616 mutex_unlock(&key_tfm_list_mutex);
1617 return 0;
1618 }
1619
1620 int
ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm ** key_tfm,char * cipher_name,size_t key_size)1621 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1622 size_t key_size)
1623 {
1624 struct ecryptfs_key_tfm *tmp_tfm;
1625 int rc = 0;
1626
1627 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1628
1629 tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1630 if (key_tfm)
1631 (*key_tfm) = tmp_tfm;
1632 if (!tmp_tfm) {
1633 rc = -ENOMEM;
1634 goto out;
1635 }
1636 mutex_init(&tmp_tfm->key_tfm_mutex);
1637 strncpy(tmp_tfm->cipher_name, cipher_name,
1638 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1639 tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1640 tmp_tfm->key_size = key_size;
1641 rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1642 tmp_tfm->cipher_name,
1643 &tmp_tfm->key_size);
1644 if (rc) {
1645 printk(KERN_ERR "Error attempting to initialize key TFM "
1646 "cipher with name = [%s]; rc = [%d]\n",
1647 tmp_tfm->cipher_name, rc);
1648 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1649 if (key_tfm)
1650 (*key_tfm) = NULL;
1651 goto out;
1652 }
1653 list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1654 out:
1655 return rc;
1656 }
1657
1658 /**
1659 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1660 * @cipher_name: the name of the cipher to search for
1661 * @key_tfm: set to corresponding tfm if found
1662 *
1663 * Searches for cached key_tfm matching @cipher_name
1664 * Must be called with &key_tfm_list_mutex held
1665 * Returns 1 if found, with @key_tfm set
1666 * Returns 0 if not found, with @key_tfm set to NULL
1667 */
ecryptfs_tfm_exists(char * cipher_name,struct ecryptfs_key_tfm ** key_tfm)1668 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1669 {
1670 struct ecryptfs_key_tfm *tmp_key_tfm;
1671
1672 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1673
1674 list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1675 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1676 if (key_tfm)
1677 (*key_tfm) = tmp_key_tfm;
1678 return 1;
1679 }
1680 }
1681 if (key_tfm)
1682 (*key_tfm) = NULL;
1683 return 0;
1684 }
1685
1686 /**
1687 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1688 *
1689 * @tfm: set to cached tfm found, or new tfm created
1690 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1691 * @cipher_name: the name of the cipher to search for and/or add
1692 *
1693 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1694 * Searches for cached item first, and creates new if not found.
1695 * Returns 0 on success, non-zero if adding new cipher failed
1696 */
ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher ** tfm,struct mutex ** tfm_mutex,char * cipher_name)1697 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1698 struct mutex **tfm_mutex,
1699 char *cipher_name)
1700 {
1701 struct ecryptfs_key_tfm *key_tfm;
1702 int rc = 0;
1703
1704 (*tfm) = NULL;
1705 (*tfm_mutex) = NULL;
1706
1707 mutex_lock(&key_tfm_list_mutex);
1708 if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1709 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1710 if (rc) {
1711 printk(KERN_ERR "Error adding new key_tfm to list; "
1712 "rc = [%d]\n", rc);
1713 goto out;
1714 }
1715 }
1716 (*tfm) = key_tfm->key_tfm;
1717 (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1718 out:
1719 mutex_unlock(&key_tfm_list_mutex);
1720 return rc;
1721 }
1722
1723 /* 64 characters forming a 6-bit target field */
1724 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1725 "EFGHIJKLMNOPQRST"
1726 "UVWXYZabcdefghij"
1727 "klmnopqrstuvwxyz");
1728
1729 /* We could either offset on every reverse map or just pad some 0x00's
1730 * at the front here */
1731 static const unsigned char filename_rev_map[256] = {
1732 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1733 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1734 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1735 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1736 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1737 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1738 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1739 0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1740 0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1741 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1742 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1743 0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1744 0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1745 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1746 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1747 0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1748 };
1749
1750 /**
1751 * ecryptfs_encode_for_filename
1752 * @dst: Destination location for encoded filename
1753 * @dst_size: Size of the encoded filename in bytes
1754 * @src: Source location for the filename to encode
1755 * @src_size: Size of the source in bytes
1756 */
ecryptfs_encode_for_filename(unsigned char * dst,size_t * dst_size,unsigned char * src,size_t src_size)1757 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1758 unsigned char *src, size_t src_size)
1759 {
1760 size_t num_blocks;
1761 size_t block_num = 0;
1762 size_t dst_offset = 0;
1763 unsigned char last_block[3];
1764
1765 if (src_size == 0) {
1766 (*dst_size) = 0;
1767 goto out;
1768 }
1769 num_blocks = (src_size / 3);
1770 if ((src_size % 3) == 0) {
1771 memcpy(last_block, (&src[src_size - 3]), 3);
1772 } else {
1773 num_blocks++;
1774 last_block[2] = 0x00;
1775 switch (src_size % 3) {
1776 case 1:
1777 last_block[0] = src[src_size - 1];
1778 last_block[1] = 0x00;
1779 break;
1780 case 2:
1781 last_block[0] = src[src_size - 2];
1782 last_block[1] = src[src_size - 1];
1783 }
1784 }
1785 (*dst_size) = (num_blocks * 4);
1786 if (!dst)
1787 goto out;
1788 while (block_num < num_blocks) {
1789 unsigned char *src_block;
1790 unsigned char dst_block[4];
1791
1792 if (block_num == (num_blocks - 1))
1793 src_block = last_block;
1794 else
1795 src_block = &src[block_num * 3];
1796 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1797 dst_block[1] = (((src_block[0] << 4) & 0x30)
1798 | ((src_block[1] >> 4) & 0x0F));
1799 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1800 | ((src_block[2] >> 6) & 0x03));
1801 dst_block[3] = (src_block[2] & 0x3F);
1802 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1803 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1804 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1805 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1806 block_num++;
1807 }
1808 out:
1809 return;
1810 }
1811
ecryptfs_max_decoded_size(size_t encoded_size)1812 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1813 {
1814 /* Not exact; conservatively long. Every block of 4
1815 * encoded characters decodes into a block of 3
1816 * decoded characters. This segment of code provides
1817 * the caller with the maximum amount of allocated
1818 * space that @dst will need to point to in a
1819 * subsequent call. */
1820 return ((encoded_size + 1) * 3) / 4;
1821 }
1822
1823 /**
1824 * ecryptfs_decode_from_filename
1825 * @dst: If NULL, this function only sets @dst_size and returns. If
1826 * non-NULL, this function decodes the encoded octets in @src
1827 * into the memory that @dst points to.
1828 * @dst_size: Set to the size of the decoded string.
1829 * @src: The encoded set of octets to decode.
1830 * @src_size: The size of the encoded set of octets to decode.
1831 */
1832 static void
ecryptfs_decode_from_filename(unsigned char * dst,size_t * dst_size,const unsigned char * src,size_t src_size)1833 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1834 const unsigned char *src, size_t src_size)
1835 {
1836 u8 current_bit_offset = 0;
1837 size_t src_byte_offset = 0;
1838 size_t dst_byte_offset = 0;
1839
1840 if (!dst) {
1841 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1842 goto out;
1843 }
1844 while (src_byte_offset < src_size) {
1845 unsigned char src_byte =
1846 filename_rev_map[(int)src[src_byte_offset]];
1847
1848 switch (current_bit_offset) {
1849 case 0:
1850 dst[dst_byte_offset] = (src_byte << 2);
1851 current_bit_offset = 6;
1852 break;
1853 case 6:
1854 dst[dst_byte_offset++] |= (src_byte >> 4);
1855 dst[dst_byte_offset] = ((src_byte & 0xF)
1856 << 4);
1857 current_bit_offset = 4;
1858 break;
1859 case 4:
1860 dst[dst_byte_offset++] |= (src_byte >> 2);
1861 dst[dst_byte_offset] = (src_byte << 6);
1862 current_bit_offset = 2;
1863 break;
1864 case 2:
1865 dst[dst_byte_offset++] |= (src_byte);
1866 current_bit_offset = 0;
1867 break;
1868 }
1869 src_byte_offset++;
1870 }
1871 (*dst_size) = dst_byte_offset;
1872 out:
1873 return;
1874 }
1875
1876 /**
1877 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1878 * @encoded_name: The encrypted name
1879 * @encoded_name_size: Length of the encrypted name
1880 * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1881 * @name: The plaintext name
1882 * @name_size: The length of the plaintext name
1883 *
1884 * Encrypts and encodes a filename into something that constitutes a
1885 * valid filename for a filesystem, with printable characters.
1886 *
1887 * We assume that we have a properly initialized crypto context,
1888 * pointed to by crypt_stat->tfm.
1889 *
1890 * Returns zero on success; non-zero on otherwise
1891 */
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)1892 int ecryptfs_encrypt_and_encode_filename(
1893 char **encoded_name,
1894 size_t *encoded_name_size,
1895 struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1896 const char *name, size_t name_size)
1897 {
1898 size_t encoded_name_no_prefix_size;
1899 int rc = 0;
1900
1901 (*encoded_name) = NULL;
1902 (*encoded_name_size) = 0;
1903 if (mount_crypt_stat && (mount_crypt_stat->flags
1904 & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1905 struct ecryptfs_filename *filename;
1906
1907 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1908 if (!filename) {
1909 rc = -ENOMEM;
1910 goto out;
1911 }
1912 filename->filename = (char *)name;
1913 filename->filename_size = name_size;
1914 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1915 if (rc) {
1916 printk(KERN_ERR "%s: Error attempting to encrypt "
1917 "filename; rc = [%d]\n", __func__, rc);
1918 kfree(filename);
1919 goto out;
1920 }
1921 ecryptfs_encode_for_filename(
1922 NULL, &encoded_name_no_prefix_size,
1923 filename->encrypted_filename,
1924 filename->encrypted_filename_size);
1925 if (mount_crypt_stat
1926 && (mount_crypt_stat->flags
1927 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1928 (*encoded_name_size) =
1929 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1930 + encoded_name_no_prefix_size);
1931 else
1932 (*encoded_name_size) =
1933 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1934 + encoded_name_no_prefix_size);
1935 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1936 if (!(*encoded_name)) {
1937 rc = -ENOMEM;
1938 kfree(filename->encrypted_filename);
1939 kfree(filename);
1940 goto out;
1941 }
1942 if (mount_crypt_stat
1943 && (mount_crypt_stat->flags
1944 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1945 memcpy((*encoded_name),
1946 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1947 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1948 ecryptfs_encode_for_filename(
1949 ((*encoded_name)
1950 + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1951 &encoded_name_no_prefix_size,
1952 filename->encrypted_filename,
1953 filename->encrypted_filename_size);
1954 (*encoded_name_size) =
1955 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1956 + encoded_name_no_prefix_size);
1957 (*encoded_name)[(*encoded_name_size)] = '\0';
1958 } else {
1959 rc = -EOPNOTSUPP;
1960 }
1961 if (rc) {
1962 printk(KERN_ERR "%s: Error attempting to encode "
1963 "encrypted filename; rc = [%d]\n", __func__,
1964 rc);
1965 kfree((*encoded_name));
1966 (*encoded_name) = NULL;
1967 (*encoded_name_size) = 0;
1968 }
1969 kfree(filename->encrypted_filename);
1970 kfree(filename);
1971 } else {
1972 rc = ecryptfs_copy_filename(encoded_name,
1973 encoded_name_size,
1974 name, name_size);
1975 }
1976 out:
1977 return rc;
1978 }
1979
is_dot_dotdot(const char * name,size_t name_size)1980 static bool is_dot_dotdot(const char *name, size_t name_size)
1981 {
1982 if (name_size == 1 && name[0] == '.')
1983 return true;
1984 else if (name_size == 2 && name[0] == '.' && name[1] == '.')
1985 return true;
1986
1987 return false;
1988 }
1989
1990 /**
1991 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1992 * @plaintext_name: The plaintext name
1993 * @plaintext_name_size: The plaintext name size
1994 * @sb: Ecryptfs's super_block
1995 * @name: The filename in cipher text
1996 * @name_size: The cipher text name size
1997 *
1998 * Decrypts and decodes the filename.
1999 *
2000 * Returns zero on error; non-zero otherwise
2001 */
ecryptfs_decode_and_decrypt_filename(char ** plaintext_name,size_t * plaintext_name_size,struct super_block * sb,const char * name,size_t name_size)2002 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2003 size_t *plaintext_name_size,
2004 struct super_block *sb,
2005 const char *name, size_t name_size)
2006 {
2007 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2008 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2009 char *decoded_name;
2010 size_t decoded_name_size;
2011 size_t packet_size;
2012 int rc = 0;
2013
2014 if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
2015 !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
2016 if (is_dot_dotdot(name, name_size)) {
2017 rc = ecryptfs_copy_filename(plaintext_name,
2018 plaintext_name_size,
2019 name, name_size);
2020 goto out;
2021 }
2022
2023 if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
2024 strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2025 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
2026 rc = -EINVAL;
2027 goto out;
2028 }
2029
2030 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2031 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2032 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2033 name, name_size);
2034 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2035 if (!decoded_name) {
2036 rc = -ENOMEM;
2037 goto out;
2038 }
2039 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2040 name, name_size);
2041 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2042 plaintext_name_size,
2043 &packet_size,
2044 mount_crypt_stat,
2045 decoded_name,
2046 decoded_name_size);
2047 if (rc) {
2048 ecryptfs_printk(KERN_DEBUG,
2049 "%s: Could not parse tag 70 packet from filename\n",
2050 __func__);
2051 goto out_free;
2052 }
2053 } else {
2054 rc = ecryptfs_copy_filename(plaintext_name,
2055 plaintext_name_size,
2056 name, name_size);
2057 goto out;
2058 }
2059 out_free:
2060 kfree(decoded_name);
2061 out:
2062 return rc;
2063 }
2064
2065 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143
2066
ecryptfs_set_f_namelen(long * namelen,long lower_namelen,struct ecryptfs_mount_crypt_stat * mount_crypt_stat)2067 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2068 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2069 {
2070 struct crypto_skcipher *tfm;
2071 struct mutex *tfm_mutex;
2072 size_t cipher_blocksize;
2073 int rc;
2074
2075 if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2076 (*namelen) = lower_namelen;
2077 return 0;
2078 }
2079
2080 rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2081 mount_crypt_stat->global_default_fn_cipher_name);
2082 if (unlikely(rc)) {
2083 (*namelen) = 0;
2084 return rc;
2085 }
2086
2087 mutex_lock(tfm_mutex);
2088 cipher_blocksize = crypto_skcipher_blocksize(tfm);
2089 mutex_unlock(tfm_mutex);
2090
2091 /* Return an exact amount for the common cases */
2092 if (lower_namelen == NAME_MAX
2093 && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2094 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2095 return 0;
2096 }
2097
2098 /* Return a safe estimate for the uncommon cases */
2099 (*namelen) = lower_namelen;
2100 (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2101 /* Since this is the max decoded size, subtract 1 "decoded block" len */
2102 (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2103 (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2104 (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2105 /* Worst case is that the filename is padded nearly a full block size */
2106 (*namelen) -= cipher_blocksize - 1;
2107
2108 if ((*namelen) < 0)
2109 (*namelen) = 0;
2110
2111 return 0;
2112 }
2113