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