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237fead6 MH |
1 | /** |
2 | * eCryptfs: Linux filesystem encryption layer | |
3 | * | |
4 | * Copyright (C) 1997-2004 Erez Zadok | |
5 | * Copyright (C) 2001-2004 Stony Brook University | |
6 | * Copyright (C) 2004-2006 International Business Machines Corp. | |
7 | * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> | |
8 | * Michael C. Thompson <mcthomps@us.ibm.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License as | |
12 | * published by the Free Software Foundation; either version 2 of the | |
13 | * License, or (at your option) any later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, but | |
16 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public License | |
21 | * along with this program; if not, write to the Free Software | |
22 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA | |
23 | * 02111-1307, USA. | |
24 | */ | |
25 | ||
26 | #include <linux/fs.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/pagemap.h> | |
29 | #include <linux/random.h> | |
30 | #include <linux/compiler.h> | |
31 | #include <linux/key.h> | |
32 | #include <linux/namei.h> | |
33 | #include <linux/crypto.h> | |
34 | #include <linux/file.h> | |
35 | #include <linux/scatterlist.h> | |
36 | #include "ecryptfs_kernel.h" | |
37 | ||
38 | static int | |
39 | ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, | |
40 | struct page *dst_page, int dst_offset, | |
41 | struct page *src_page, int src_offset, int size, | |
42 | unsigned char *iv); | |
43 | static int | |
44 | ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, | |
45 | struct page *dst_page, int dst_offset, | |
46 | struct page *src_page, int src_offset, int size, | |
47 | unsigned char *iv); | |
48 | ||
49 | /** | |
50 | * ecryptfs_to_hex | |
51 | * @dst: Buffer to take hex character representation of contents of | |
52 | * src; must be at least of size (src_size * 2) | |
53 | * @src: Buffer to be converted to a hex string respresentation | |
54 | * @src_size: number of bytes to convert | |
55 | */ | |
56 | void ecryptfs_to_hex(char *dst, char *src, size_t src_size) | |
57 | { | |
58 | int x; | |
59 | ||
60 | for (x = 0; x < src_size; x++) | |
61 | sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]); | |
62 | } | |
63 | ||
64 | /** | |
65 | * ecryptfs_from_hex | |
66 | * @dst: Buffer to take the bytes from src hex; must be at least of | |
67 | * size (src_size / 2) | |
68 | * @src: Buffer to be converted from a hex string respresentation to raw value | |
69 | * @dst_size: size of dst buffer, or number of hex characters pairs to convert | |
70 | */ | |
71 | void ecryptfs_from_hex(char *dst, char *src, int dst_size) | |
72 | { | |
73 | int x; | |
74 | char tmp[3] = { 0, }; | |
75 | ||
76 | for (x = 0; x < dst_size; x++) { | |
77 | tmp[0] = src[x * 2]; | |
78 | tmp[1] = src[x * 2 + 1]; | |
79 | dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16); | |
80 | } | |
81 | } | |
82 | ||
83 | /** | |
84 | * ecryptfs_calculate_md5 - calculates the md5 of @src | |
85 | * @dst: Pointer to 16 bytes of allocated memory | |
86 | * @crypt_stat: Pointer to crypt_stat struct for the current inode | |
87 | * @src: Data to be md5'd | |
88 | * @len: Length of @src | |
89 | * | |
90 | * Uses the allocated crypto context that crypt_stat references to | |
91 | * generate the MD5 sum of the contents of src. | |
92 | */ | |
93 | static int ecryptfs_calculate_md5(char *dst, | |
94 | struct ecryptfs_crypt_stat *crypt_stat, | |
95 | char *src, int len) | |
96 | { | |
237fead6 | 97 | struct scatterlist sg; |
565d9724 MH |
98 | struct hash_desc desc = { |
99 | .tfm = crypt_stat->hash_tfm, | |
100 | .flags = CRYPTO_TFM_REQ_MAY_SLEEP | |
101 | }; | |
102 | int rc = 0; | |
237fead6 | 103 | |
565d9724 | 104 | mutex_lock(&crypt_stat->cs_hash_tfm_mutex); |
237fead6 | 105 | sg_init_one(&sg, (u8 *)src, len); |
565d9724 MH |
106 | if (!desc.tfm) { |
107 | desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0, | |
108 | CRYPTO_ALG_ASYNC); | |
109 | if (IS_ERR(desc.tfm)) { | |
110 | rc = PTR_ERR(desc.tfm); | |
237fead6 | 111 | ecryptfs_printk(KERN_ERR, "Error attempting to " |
565d9724 MH |
112 | "allocate crypto context; rc = [%d]\n", |
113 | rc); | |
237fead6 MH |
114 | goto out; |
115 | } | |
565d9724 | 116 | crypt_stat->hash_tfm = desc.tfm; |
237fead6 | 117 | } |
565d9724 MH |
118 | crypto_hash_init(&desc); |
119 | crypto_hash_update(&desc, &sg, len); | |
120 | crypto_hash_final(&desc, dst); | |
121 | mutex_unlock(&crypt_stat->cs_hash_tfm_mutex); | |
237fead6 MH |
122 | out: |
123 | return rc; | |
124 | } | |
125 | ||
126 | /** | |
127 | * ecryptfs_derive_iv | |
128 | * @iv: destination for the derived iv vale | |
129 | * @crypt_stat: Pointer to crypt_stat struct for the current inode | |
130 | * @offset: Offset of the page whose's iv we are to derive | |
131 | * | |
132 | * Generate the initialization vector from the given root IV and page | |
133 | * offset. | |
134 | * | |
135 | * Returns zero on success; non-zero on error. | |
136 | */ | |
137 | static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat, | |
138 | pgoff_t offset) | |
139 | { | |
140 | int rc = 0; | |
141 | char dst[MD5_DIGEST_SIZE]; | |
142 | char src[ECRYPTFS_MAX_IV_BYTES + 16]; | |
143 | ||
144 | if (unlikely(ecryptfs_verbosity > 0)) { | |
145 | ecryptfs_printk(KERN_DEBUG, "root iv:\n"); | |
146 | ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes); | |
147 | } | |
148 | /* TODO: It is probably secure to just cast the least | |
149 | * significant bits of the root IV into an unsigned long and | |
150 | * add the offset to that rather than go through all this | |
151 | * hashing business. -Halcrow */ | |
152 | memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes); | |
153 | memset((src + crypt_stat->iv_bytes), 0, 16); | |
154 | snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset); | |
155 | if (unlikely(ecryptfs_verbosity > 0)) { | |
156 | ecryptfs_printk(KERN_DEBUG, "source:\n"); | |
157 | ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16)); | |
158 | } | |
159 | rc = ecryptfs_calculate_md5(dst, crypt_stat, src, | |
160 | (crypt_stat->iv_bytes + 16)); | |
161 | if (rc) { | |
162 | ecryptfs_printk(KERN_WARNING, "Error attempting to compute " | |
163 | "MD5 while generating IV for a page\n"); | |
164 | goto out; | |
165 | } | |
166 | memcpy(iv, dst, crypt_stat->iv_bytes); | |
167 | if (unlikely(ecryptfs_verbosity > 0)) { | |
168 | ecryptfs_printk(KERN_DEBUG, "derived iv:\n"); | |
169 | ecryptfs_dump_hex(iv, crypt_stat->iv_bytes); | |
170 | } | |
171 | out: | |
172 | return rc; | |
173 | } | |
174 | ||
175 | /** | |
176 | * ecryptfs_init_crypt_stat | |
177 | * @crypt_stat: Pointer to the crypt_stat struct to initialize. | |
178 | * | |
179 | * Initialize the crypt_stat structure. | |
180 | */ | |
181 | void | |
182 | ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) | |
183 | { | |
184 | memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); | |
185 | mutex_init(&crypt_stat->cs_mutex); | |
186 | mutex_init(&crypt_stat->cs_tfm_mutex); | |
565d9724 | 187 | mutex_init(&crypt_stat->cs_hash_tfm_mutex); |
237fead6 MH |
188 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED); |
189 | } | |
190 | ||
191 | /** | |
192 | * ecryptfs_destruct_crypt_stat | |
193 | * @crypt_stat: Pointer to the crypt_stat struct to initialize. | |
194 | * | |
195 | * Releases all memory associated with a crypt_stat struct. | |
196 | */ | |
197 | void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) | |
198 | { | |
199 | if (crypt_stat->tfm) | |
200 | crypto_free_tfm(crypt_stat->tfm); | |
565d9724 MH |
201 | if (crypt_stat->hash_tfm) |
202 | crypto_free_hash(crypt_stat->hash_tfm); | |
237fead6 MH |
203 | memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); |
204 | } | |
205 | ||
206 | void ecryptfs_destruct_mount_crypt_stat( | |
207 | struct ecryptfs_mount_crypt_stat *mount_crypt_stat) | |
208 | { | |
209 | if (mount_crypt_stat->global_auth_tok_key) | |
210 | key_put(mount_crypt_stat->global_auth_tok_key); | |
211 | if (mount_crypt_stat->global_key_tfm) | |
212 | crypto_free_tfm(mount_crypt_stat->global_key_tfm); | |
213 | memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat)); | |
214 | } | |
215 | ||
216 | /** | |
217 | * virt_to_scatterlist | |
218 | * @addr: Virtual address | |
219 | * @size: Size of data; should be an even multiple of the block size | |
220 | * @sg: Pointer to scatterlist array; set to NULL to obtain only | |
221 | * the number of scatterlist structs required in array | |
222 | * @sg_size: Max array size | |
223 | * | |
224 | * Fills in a scatterlist array with page references for a passed | |
225 | * virtual address. | |
226 | * | |
227 | * Returns the number of scatterlist structs in array used | |
228 | */ | |
229 | int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg, | |
230 | int sg_size) | |
231 | { | |
232 | int i = 0; | |
233 | struct page *pg; | |
234 | int offset; | |
235 | int remainder_of_page; | |
236 | ||
237 | while (size > 0 && i < sg_size) { | |
238 | pg = virt_to_page(addr); | |
239 | offset = offset_in_page(addr); | |
240 | if (sg) { | |
241 | sg[i].page = pg; | |
242 | sg[i].offset = offset; | |
243 | } | |
244 | remainder_of_page = PAGE_CACHE_SIZE - offset; | |
245 | if (size >= remainder_of_page) { | |
246 | if (sg) | |
247 | sg[i].length = remainder_of_page; | |
248 | addr += remainder_of_page; | |
249 | size -= remainder_of_page; | |
250 | } else { | |
251 | if (sg) | |
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 | /** | |
264 | * encrypt_scatterlist | |
265 | * @crypt_stat: Pointer to the crypt_stat struct to initialize. | |
266 | * @dest_sg: Destination of encrypted data | |
267 | * @src_sg: Data to be encrypted | |
268 | * @size: Length of data to be encrypted | |
269 | * @iv: iv to use during encryption | |
270 | * | |
271 | * Returns the number of bytes encrypted; negative value on error | |
272 | */ | |
273 | static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, | |
274 | struct scatterlist *dest_sg, | |
275 | struct scatterlist *src_sg, int size, | |
276 | unsigned char *iv) | |
277 | { | |
278 | int rc = 0; | |
279 | ||
280 | BUG_ON(!crypt_stat || !crypt_stat->tfm | |
281 | || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
282 | ECRYPTFS_STRUCT_INITIALIZED)); | |
283 | if (unlikely(ecryptfs_verbosity > 0)) { | |
284 | ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n", | |
285 | crypt_stat->key_size); | |
286 | ecryptfs_dump_hex(crypt_stat->key, | |
287 | crypt_stat->key_size); | |
288 | } | |
289 | /* Consider doing this once, when the file is opened */ | |
290 | mutex_lock(&crypt_stat->cs_tfm_mutex); | |
291 | rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key, | |
292 | crypt_stat->key_size); | |
293 | if (rc) { | |
294 | ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n", | |
295 | rc); | |
296 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
297 | rc = -EINVAL; | |
298 | goto out; | |
299 | } | |
300 | ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size); | |
301 | crypto_cipher_encrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, iv); | |
302 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
303 | out: | |
304 | return rc; | |
305 | } | |
306 | ||
307 | static void | |
308 | ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx, | |
309 | int *byte_offset, | |
310 | struct ecryptfs_crypt_stat *crypt_stat, | |
311 | unsigned long extent_num) | |
312 | { | |
313 | unsigned long lower_extent_num; | |
314 | int extents_occupied_by_headers_at_front; | |
315 | int bytes_occupied_by_headers_at_front; | |
316 | int extent_offset; | |
317 | int extents_per_page; | |
318 | ||
319 | bytes_occupied_by_headers_at_front = | |
320 | ( crypt_stat->header_extent_size | |
321 | * crypt_stat->num_header_extents_at_front ); | |
322 | extents_occupied_by_headers_at_front = | |
323 | ( bytes_occupied_by_headers_at_front | |
324 | / crypt_stat->extent_size ); | |
325 | lower_extent_num = extents_occupied_by_headers_at_front + extent_num; | |
326 | extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; | |
327 | (*lower_page_idx) = lower_extent_num / extents_per_page; | |
328 | extent_offset = lower_extent_num % extents_per_page; | |
329 | (*byte_offset) = extent_offset * crypt_stat->extent_size; | |
330 | ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = " | |
331 | "[%d]\n", crypt_stat->header_extent_size); | |
332 | ecryptfs_printk(KERN_DEBUG, " * crypt_stat->" | |
333 | "num_header_extents_at_front = [%d]\n", | |
334 | crypt_stat->num_header_extents_at_front); | |
335 | ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_" | |
336 | "front = [%d]\n", extents_occupied_by_headers_at_front); | |
337 | ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n", | |
338 | lower_extent_num); | |
339 | ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n", | |
340 | extents_per_page); | |
341 | ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n", | |
342 | (*lower_page_idx)); | |
343 | ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n", | |
344 | extent_offset); | |
345 | ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n", | |
346 | (*byte_offset)); | |
347 | } | |
348 | ||
349 | static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx, | |
350 | struct page *lower_page, | |
351 | struct inode *lower_inode, | |
352 | int byte_offset_in_page, int bytes_to_write) | |
353 | { | |
354 | int rc = 0; | |
355 | ||
356 | if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) { | |
357 | rc = ecryptfs_commit_lower_page(lower_page, lower_inode, | |
358 | ctx->param.lower_file, | |
359 | byte_offset_in_page, | |
360 | bytes_to_write); | |
361 | if (rc) { | |
362 | ecryptfs_printk(KERN_ERR, "Error calling lower " | |
363 | "commit; rc = [%d]\n", rc); | |
364 | goto out; | |
365 | } | |
366 | } else { | |
367 | rc = ecryptfs_writepage_and_release_lower_page(lower_page, | |
368 | lower_inode, | |
369 | ctx->param.wbc); | |
370 | if (rc) { | |
371 | ecryptfs_printk(KERN_ERR, "Error calling lower " | |
372 | "writepage(); rc = [%d]\n", rc); | |
373 | goto out; | |
374 | } | |
375 | } | |
376 | out: | |
377 | return rc; | |
378 | } | |
379 | ||
380 | static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx, | |
381 | struct page **lower_page, | |
382 | struct inode *lower_inode, | |
383 | unsigned long lower_page_idx, | |
384 | int byte_offset_in_page) | |
385 | { | |
386 | int rc = 0; | |
387 | ||
388 | if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) { | |
389 | /* TODO: Limit this to only the data extents that are | |
390 | * needed */ | |
391 | rc = ecryptfs_get_lower_page(lower_page, lower_inode, | |
392 | ctx->param.lower_file, | |
393 | lower_page_idx, | |
394 | byte_offset_in_page, | |
395 | (PAGE_CACHE_SIZE | |
396 | - byte_offset_in_page)); | |
397 | if (rc) { | |
398 | ecryptfs_printk( | |
399 | KERN_ERR, "Error attempting to grab, map, " | |
400 | "and prepare_write lower page with index " | |
401 | "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc); | |
402 | goto out; | |
403 | } | |
404 | } else { | |
405 | rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, | |
406 | lower_inode, | |
407 | lower_page_idx); | |
408 | if (rc) { | |
409 | ecryptfs_printk( | |
410 | KERN_ERR, "Error attempting to grab and map " | |
411 | "lower page with index [0x%.16x]; rc = [%d]\n", | |
412 | lower_page_idx, rc); | |
413 | goto out; | |
414 | } | |
415 | } | |
416 | out: | |
417 | return rc; | |
418 | } | |
419 | ||
420 | /** | |
421 | * ecryptfs_encrypt_page | |
422 | * @ctx: The context of the page | |
423 | * | |
424 | * Encrypt an eCryptfs page. This is done on a per-extent basis. Note | |
425 | * that eCryptfs pages may straddle the lower pages -- for instance, | |
426 | * if the file was created on a machine with an 8K page size | |
427 | * (resulting in an 8K header), and then the file is copied onto a | |
428 | * host with a 32K page size, then when reading page 0 of the eCryptfs | |
429 | * file, 24K of page 0 of the lower file will be read and decrypted, | |
430 | * and then 8K of page 1 of the lower file will be read and decrypted. | |
431 | * | |
432 | * The actual operations performed on each page depends on the | |
433 | * contents of the ecryptfs_page_crypt_context struct. | |
434 | * | |
435 | * Returns zero on success; negative on error | |
436 | */ | |
437 | int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx) | |
438 | { | |
439 | char extent_iv[ECRYPTFS_MAX_IV_BYTES]; | |
440 | unsigned long base_extent; | |
441 | unsigned long extent_offset = 0; | |
442 | unsigned long lower_page_idx = 0; | |
443 | unsigned long prior_lower_page_idx = 0; | |
444 | struct page *lower_page; | |
445 | struct inode *lower_inode; | |
446 | struct ecryptfs_inode_info *inode_info; | |
447 | struct ecryptfs_crypt_stat *crypt_stat; | |
448 | int rc = 0; | |
449 | int lower_byte_offset = 0; | |
450 | int orig_byte_offset = 0; | |
451 | int num_extents_per_page; | |
452 | #define ECRYPTFS_PAGE_STATE_UNREAD 0 | |
453 | #define ECRYPTFS_PAGE_STATE_READ 1 | |
454 | #define ECRYPTFS_PAGE_STATE_MODIFIED 2 | |
455 | #define ECRYPTFS_PAGE_STATE_WRITTEN 3 | |
456 | int page_state; | |
457 | ||
458 | lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host); | |
459 | inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host); | |
460 | crypt_stat = &inode_info->crypt_stat; | |
461 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) { | |
462 | rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode, | |
463 | ctx->param.lower_file); | |
464 | if (rc) | |
465 | ecryptfs_printk(KERN_ERR, "Error attempting to copy " | |
466 | "page at index [0x%.16x]\n", | |
467 | ctx->page->index); | |
468 | goto out; | |
469 | } | |
470 | num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; | |
471 | base_extent = (ctx->page->index * num_extents_per_page); | |
472 | page_state = ECRYPTFS_PAGE_STATE_UNREAD; | |
473 | while (extent_offset < num_extents_per_page) { | |
474 | ecryptfs_extent_to_lwr_pg_idx_and_offset( | |
475 | &lower_page_idx, &lower_byte_offset, crypt_stat, | |
476 | (base_extent + extent_offset)); | |
477 | if (prior_lower_page_idx != lower_page_idx | |
478 | && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) { | |
479 | rc = ecryptfs_write_out_page(ctx, lower_page, | |
480 | lower_inode, | |
481 | orig_byte_offset, | |
482 | (PAGE_CACHE_SIZE | |
483 | - orig_byte_offset)); | |
484 | if (rc) { | |
485 | ecryptfs_printk(KERN_ERR, "Error attempting " | |
486 | "to write out page; rc = [%d]" | |
487 | "\n", rc); | |
488 | goto out; | |
489 | } | |
490 | page_state = ECRYPTFS_PAGE_STATE_WRITTEN; | |
491 | } | |
492 | if (page_state == ECRYPTFS_PAGE_STATE_UNREAD | |
493 | || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) { | |
494 | rc = ecryptfs_read_in_page(ctx, &lower_page, | |
495 | lower_inode, lower_page_idx, | |
496 | lower_byte_offset); | |
497 | if (rc) { | |
498 | ecryptfs_printk(KERN_ERR, "Error attempting " | |
499 | "to read in lower page with " | |
500 | "index [0x%.16x]; rc = [%d]\n", | |
501 | lower_page_idx, rc); | |
502 | goto out; | |
503 | } | |
504 | orig_byte_offset = lower_byte_offset; | |
505 | prior_lower_page_idx = lower_page_idx; | |
506 | page_state = ECRYPTFS_PAGE_STATE_READ; | |
507 | } | |
508 | BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED | |
509 | || page_state == ECRYPTFS_PAGE_STATE_READ)); | |
510 | rc = ecryptfs_derive_iv(extent_iv, crypt_stat, | |
511 | (base_extent + extent_offset)); | |
512 | if (rc) { | |
513 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
514 | "derive IV for extent [0x%.16x]; " | |
515 | "rc = [%d]\n", | |
516 | (base_extent + extent_offset), rc); | |
517 | goto out; | |
518 | } | |
519 | if (unlikely(ecryptfs_verbosity > 0)) { | |
520 | ecryptfs_printk(KERN_DEBUG, "Encrypting extent " | |
521 | "with iv:\n"); | |
522 | ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes); | |
523 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes before " | |
524 | "encryption:\n"); | |
525 | ecryptfs_dump_hex((char *) | |
526 | (page_address(ctx->page) | |
527 | + (extent_offset | |
528 | * crypt_stat->extent_size)), 8); | |
529 | } | |
530 | rc = ecryptfs_encrypt_page_offset( | |
531 | crypt_stat, lower_page, lower_byte_offset, ctx->page, | |
532 | (extent_offset * crypt_stat->extent_size), | |
533 | crypt_stat->extent_size, extent_iv); | |
534 | ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; " | |
535 | "rc = [%d]\n", | |
536 | (base_extent + extent_offset), rc); | |
537 | if (unlikely(ecryptfs_verbosity > 0)) { | |
538 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes after " | |
539 | "encryption:\n"); | |
540 | ecryptfs_dump_hex((char *)(page_address(lower_page) | |
541 | + lower_byte_offset), 8); | |
542 | } | |
543 | page_state = ECRYPTFS_PAGE_STATE_MODIFIED; | |
544 | extent_offset++; | |
545 | } | |
546 | BUG_ON(orig_byte_offset != 0); | |
547 | rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0, | |
548 | (lower_byte_offset | |
549 | + crypt_stat->extent_size)); | |
550 | if (rc) { | |
551 | ecryptfs_printk(KERN_ERR, "Error attempting to write out " | |
552 | "page; rc = [%d]\n", rc); | |
553 | goto out; | |
554 | } | |
555 | out: | |
556 | return rc; | |
557 | } | |
558 | ||
559 | /** | |
560 | * ecryptfs_decrypt_page | |
561 | * @file: The ecryptfs file | |
562 | * @page: The page in ecryptfs to decrypt | |
563 | * | |
564 | * Decrypt an eCryptfs page. This is done on a per-extent basis. Note | |
565 | * that eCryptfs pages may straddle the lower pages -- for instance, | |
566 | * if the file was created on a machine with an 8K page size | |
567 | * (resulting in an 8K header), and then the file is copied onto a | |
568 | * host with a 32K page size, then when reading page 0 of the eCryptfs | |
569 | * file, 24K of page 0 of the lower file will be read and decrypted, | |
570 | * and then 8K of page 1 of the lower file will be read and decrypted. | |
571 | * | |
572 | * Returns zero on success; negative on error | |
573 | */ | |
574 | int ecryptfs_decrypt_page(struct file *file, struct page *page) | |
575 | { | |
576 | char extent_iv[ECRYPTFS_MAX_IV_BYTES]; | |
577 | unsigned long base_extent; | |
578 | unsigned long extent_offset = 0; | |
579 | unsigned long lower_page_idx = 0; | |
580 | unsigned long prior_lower_page_idx = 0; | |
581 | struct page *lower_page; | |
582 | char *lower_page_virt = NULL; | |
583 | struct inode *lower_inode; | |
584 | struct ecryptfs_crypt_stat *crypt_stat; | |
585 | int rc = 0; | |
586 | int byte_offset; | |
587 | int num_extents_per_page; | |
588 | int page_state; | |
589 | ||
590 | crypt_stat = &(ecryptfs_inode_to_private( | |
591 | page->mapping->host)->crypt_stat); | |
592 | lower_inode = ecryptfs_inode_to_lower(page->mapping->host); | |
593 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) { | |
594 | rc = ecryptfs_do_readpage(file, page, page->index); | |
595 | if (rc) | |
596 | ecryptfs_printk(KERN_ERR, "Error attempting to copy " | |
597 | "page at index [0x%.16x]\n", | |
598 | page->index); | |
599 | goto out; | |
600 | } | |
601 | num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; | |
602 | base_extent = (page->index * num_extents_per_page); | |
603 | lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache, | |
604 | SLAB_KERNEL); | |
605 | if (!lower_page_virt) { | |
606 | rc = -ENOMEM; | |
607 | ecryptfs_printk(KERN_ERR, "Error getting page for encrypted " | |
608 | "lower page(s)\n"); | |
609 | goto out; | |
610 | } | |
611 | lower_page = virt_to_page(lower_page_virt); | |
612 | page_state = ECRYPTFS_PAGE_STATE_UNREAD; | |
613 | while (extent_offset < num_extents_per_page) { | |
614 | ecryptfs_extent_to_lwr_pg_idx_and_offset( | |
615 | &lower_page_idx, &byte_offset, crypt_stat, | |
616 | (base_extent + extent_offset)); | |
617 | if (prior_lower_page_idx != lower_page_idx | |
618 | || page_state == ECRYPTFS_PAGE_STATE_UNREAD) { | |
619 | rc = ecryptfs_do_readpage(file, lower_page, | |
620 | lower_page_idx); | |
621 | if (rc) { | |
622 | ecryptfs_printk(KERN_ERR, "Error reading " | |
623 | "lower encrypted page; rc = " | |
624 | "[%d]\n", rc); | |
625 | goto out; | |
626 | } | |
627 | prior_lower_page_idx = lower_page_idx; | |
628 | page_state = ECRYPTFS_PAGE_STATE_READ; | |
629 | } | |
630 | rc = ecryptfs_derive_iv(extent_iv, crypt_stat, | |
631 | (base_extent + extent_offset)); | |
632 | if (rc) { | |
633 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
634 | "derive IV for extent [0x%.16x]; rc = " | |
635 | "[%d]\n", | |
636 | (base_extent + extent_offset), rc); | |
637 | goto out; | |
638 | } | |
639 | if (unlikely(ecryptfs_verbosity > 0)) { | |
640 | ecryptfs_printk(KERN_DEBUG, "Decrypting extent " | |
641 | "with iv:\n"); | |
642 | ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes); | |
643 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes before " | |
644 | "decryption:\n"); | |
645 | ecryptfs_dump_hex((lower_page_virt + byte_offset), 8); | |
646 | } | |
647 | rc = ecryptfs_decrypt_page_offset(crypt_stat, page, | |
648 | (extent_offset | |
649 | * crypt_stat->extent_size), | |
650 | lower_page, byte_offset, | |
651 | crypt_stat->extent_size, | |
652 | extent_iv); | |
653 | if (rc != crypt_stat->extent_size) { | |
654 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
655 | "decrypt extent [0x%.16x]\n", | |
656 | (base_extent + extent_offset)); | |
657 | goto out; | |
658 | } | |
659 | rc = 0; | |
660 | if (unlikely(ecryptfs_verbosity > 0)) { | |
661 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes after " | |
662 | "decryption:\n"); | |
663 | ecryptfs_dump_hex((char *)(page_address(page) | |
664 | + byte_offset), 8); | |
665 | } | |
666 | extent_offset++; | |
667 | } | |
668 | out: | |
669 | if (lower_page_virt) | |
670 | kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt); | |
671 | return rc; | |
672 | } | |
673 | ||
674 | /** | |
675 | * decrypt_scatterlist | |
676 | * | |
677 | * Returns the number of bytes decrypted; negative value on error | |
678 | */ | |
679 | static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, | |
680 | struct scatterlist *dest_sg, | |
681 | struct scatterlist *src_sg, int size, | |
682 | unsigned char *iv) | |
683 | { | |
684 | int rc = 0; | |
685 | ||
686 | /* Consider doing this once, when the file is opened */ | |
687 | mutex_lock(&crypt_stat->cs_tfm_mutex); | |
688 | rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key, | |
689 | crypt_stat->key_size); | |
690 | if (rc) { | |
691 | ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n", | |
692 | rc); | |
693 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
694 | rc = -EINVAL; | |
695 | goto out; | |
696 | } | |
697 | ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size); | |
698 | rc = crypto_cipher_decrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, | |
699 | iv); | |
700 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
701 | if (rc) { | |
702 | ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n", | |
703 | rc); | |
704 | goto out; | |
705 | } | |
706 | rc = size; | |
707 | out: | |
708 | return rc; | |
709 | } | |
710 | ||
711 | /** | |
712 | * ecryptfs_encrypt_page_offset | |
713 | * | |
714 | * Returns the number of bytes encrypted | |
715 | */ | |
716 | static int | |
717 | ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, | |
718 | struct page *dst_page, int dst_offset, | |
719 | struct page *src_page, int src_offset, int size, | |
720 | unsigned char *iv) | |
721 | { | |
722 | struct scatterlist src_sg, dst_sg; | |
723 | ||
724 | src_sg.page = src_page; | |
725 | src_sg.offset = src_offset; | |
726 | src_sg.length = size; | |
727 | dst_sg.page = dst_page; | |
728 | dst_sg.offset = dst_offset; | |
729 | dst_sg.length = size; | |
730 | return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv); | |
731 | } | |
732 | ||
733 | /** | |
734 | * ecryptfs_decrypt_page_offset | |
735 | * | |
736 | * Returns the number of bytes decrypted | |
737 | */ | |
738 | static int | |
739 | ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, | |
740 | struct page *dst_page, int dst_offset, | |
741 | struct page *src_page, int src_offset, int size, | |
742 | unsigned char *iv) | |
743 | { | |
744 | struct scatterlist src_sg, dst_sg; | |
745 | ||
746 | src_sg.page = src_page; | |
747 | src_sg.offset = src_offset; | |
748 | src_sg.length = size; | |
749 | dst_sg.page = dst_page; | |
750 | dst_sg.offset = dst_offset; | |
751 | dst_sg.length = size; | |
752 | return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv); | |
753 | } | |
754 | ||
755 | #define ECRYPTFS_MAX_SCATTERLIST_LEN 4 | |
756 | ||
757 | /** | |
758 | * ecryptfs_init_crypt_ctx | |
759 | * @crypt_stat: Uninitilized crypt stats structure | |
760 | * | |
761 | * Initialize the crypto context. | |
762 | * | |
763 | * TODO: Performance: Keep a cache of initialized cipher contexts; | |
764 | * only init if needed | |
765 | */ | |
766 | int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat) | |
767 | { | |
768 | int rc = -EINVAL; | |
769 | ||
770 | if (!crypt_stat->cipher) { | |
771 | ecryptfs_printk(KERN_ERR, "No cipher specified\n"); | |
772 | goto out; | |
773 | } | |
774 | ecryptfs_printk(KERN_DEBUG, | |
775 | "Initializing cipher [%s]; strlen = [%d]; " | |
776 | "key_size_bits = [%d]\n", | |
777 | crypt_stat->cipher, (int)strlen(crypt_stat->cipher), | |
778 | crypt_stat->key_size << 3); | |
779 | if (crypt_stat->tfm) { | |
780 | rc = 0; | |
781 | goto out; | |
782 | } | |
783 | mutex_lock(&crypt_stat->cs_tfm_mutex); | |
784 | crypt_stat->tfm = crypto_alloc_tfm(crypt_stat->cipher, | |
785 | ECRYPTFS_DEFAULT_CHAINING_MODE | |
786 | | CRYPTO_TFM_REQ_WEAK_KEY); | |
787 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
788 | if (!crypt_stat->tfm) { | |
789 | ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): " | |
790 | "Error initializing cipher [%s]\n", | |
791 | crypt_stat->cipher); | |
792 | goto out; | |
793 | } | |
794 | rc = 0; | |
795 | out: | |
796 | return rc; | |
797 | } | |
798 | ||
799 | static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat) | |
800 | { | |
801 | int extent_size_tmp; | |
802 | ||
803 | crypt_stat->extent_mask = 0xFFFFFFFF; | |
804 | crypt_stat->extent_shift = 0; | |
805 | if (crypt_stat->extent_size == 0) | |
806 | return; | |
807 | extent_size_tmp = crypt_stat->extent_size; | |
808 | while ((extent_size_tmp & 0x01) == 0) { | |
809 | extent_size_tmp >>= 1; | |
810 | crypt_stat->extent_mask <<= 1; | |
811 | crypt_stat->extent_shift++; | |
812 | } | |
813 | } | |
814 | ||
815 | void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat) | |
816 | { | |
817 | /* Default values; may be overwritten as we are parsing the | |
818 | * packets. */ | |
819 | crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE; | |
820 | set_extent_mask_and_shift(crypt_stat); | |
821 | crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES; | |
822 | if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) { | |
823 | crypt_stat->header_extent_size = | |
824 | ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE; | |
825 | } else | |
826 | crypt_stat->header_extent_size = PAGE_CACHE_SIZE; | |
827 | crypt_stat->num_header_extents_at_front = 1; | |
828 | } | |
829 | ||
830 | /** | |
831 | * ecryptfs_compute_root_iv | |
832 | * @crypt_stats | |
833 | * | |
834 | * On error, sets the root IV to all 0's. | |
835 | */ | |
836 | int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat) | |
837 | { | |
838 | int rc = 0; | |
839 | char dst[MD5_DIGEST_SIZE]; | |
840 | ||
841 | BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE); | |
842 | BUG_ON(crypt_stat->iv_bytes <= 0); | |
843 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) { | |
844 | rc = -EINVAL; | |
845 | ecryptfs_printk(KERN_WARNING, "Session key not valid; " | |
846 | "cannot generate root IV\n"); | |
847 | goto out; | |
848 | } | |
849 | rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key, | |
850 | crypt_stat->key_size); | |
851 | if (rc) { | |
852 | ecryptfs_printk(KERN_WARNING, "Error attempting to compute " | |
853 | "MD5 while generating root IV\n"); | |
854 | goto out; | |
855 | } | |
856 | memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes); | |
857 | out: | |
858 | if (rc) { | |
859 | memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes); | |
860 | ECRYPTFS_SET_FLAG(crypt_stat->flags, | |
861 | ECRYPTFS_SECURITY_WARNING); | |
862 | } | |
863 | return rc; | |
864 | } | |
865 | ||
866 | static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat) | |
867 | { | |
868 | get_random_bytes(crypt_stat->key, crypt_stat->key_size); | |
869 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); | |
870 | ecryptfs_compute_root_iv(crypt_stat); | |
871 | if (unlikely(ecryptfs_verbosity > 0)) { | |
872 | ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n"); | |
873 | ecryptfs_dump_hex(crypt_stat->key, | |
874 | crypt_stat->key_size); | |
875 | } | |
876 | } | |
877 | ||
878 | /** | |
879 | * ecryptfs_set_default_crypt_stat_vals | |
880 | * @crypt_stat | |
881 | * | |
882 | * Default values in the event that policy does not override them. | |
883 | */ | |
884 | static void ecryptfs_set_default_crypt_stat_vals( | |
885 | struct ecryptfs_crypt_stat *crypt_stat, | |
886 | struct ecryptfs_mount_crypt_stat *mount_crypt_stat) | |
887 | { | |
888 | ecryptfs_set_default_sizes(crypt_stat); | |
889 | strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER); | |
890 | crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES; | |
891 | ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); | |
892 | crypt_stat->file_version = ECRYPTFS_FILE_VERSION; | |
893 | crypt_stat->mount_crypt_stat = mount_crypt_stat; | |
894 | } | |
895 | ||
896 | /** | |
897 | * ecryptfs_new_file_context | |
898 | * @ecryptfs_dentry | |
899 | * | |
900 | * If the crypto context for the file has not yet been established, | |
901 | * this is where we do that. Establishing a new crypto context | |
902 | * involves the following decisions: | |
903 | * - What cipher to use? | |
904 | * - What set of authentication tokens to use? | |
905 | * Here we just worry about getting enough information into the | |
906 | * authentication tokens so that we know that they are available. | |
907 | * We associate the available authentication tokens with the new file | |
908 | * via the set of signatures in the crypt_stat struct. Later, when | |
909 | * the headers are actually written out, we may again defer to | |
910 | * userspace to perform the encryption of the session key; for the | |
911 | * foreseeable future, this will be the case with public key packets. | |
912 | * | |
913 | * Returns zero on success; non-zero otherwise | |
914 | */ | |
915 | /* Associate an authentication token(s) with the file */ | |
916 | int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry) | |
917 | { | |
918 | int rc = 0; | |
919 | struct ecryptfs_crypt_stat *crypt_stat = | |
920 | &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat; | |
921 | struct ecryptfs_mount_crypt_stat *mount_crypt_stat = | |
922 | &ecryptfs_superblock_to_private( | |
923 | ecryptfs_dentry->d_sb)->mount_crypt_stat; | |
924 | int cipher_name_len; | |
925 | ||
926 | ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat); | |
927 | /* See if there are mount crypt options */ | |
928 | if (mount_crypt_stat->global_auth_tok) { | |
929 | ecryptfs_printk(KERN_DEBUG, "Initializing context for new " | |
930 | "file using mount_crypt_stat\n"); | |
931 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED); | |
932 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); | |
933 | memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++], | |
934 | mount_crypt_stat->global_auth_tok_sig, | |
935 | ECRYPTFS_SIG_SIZE_HEX); | |
936 | cipher_name_len = | |
937 | strlen(mount_crypt_stat->global_default_cipher_name); | |
938 | memcpy(crypt_stat->cipher, | |
939 | mount_crypt_stat->global_default_cipher_name, | |
940 | cipher_name_len); | |
941 | crypt_stat->cipher[cipher_name_len] = '\0'; | |
942 | crypt_stat->key_size = | |
943 | mount_crypt_stat->global_default_cipher_key_size; | |
944 | ecryptfs_generate_new_key(crypt_stat); | |
945 | } else | |
946 | /* We should not encounter this scenario since we | |
947 | * should detect lack of global_auth_tok at mount time | |
948 | * TODO: Applies to 0.1 release only; remove in future | |
949 | * release */ | |
950 | BUG(); | |
951 | rc = ecryptfs_init_crypt_ctx(crypt_stat); | |
952 | if (rc) | |
953 | ecryptfs_printk(KERN_ERR, "Error initializing cryptographic " | |
954 | "context for cipher [%s]: rc = [%d]\n", | |
955 | crypt_stat->cipher, rc); | |
956 | return rc; | |
957 | } | |
958 | ||
959 | /** | |
960 | * contains_ecryptfs_marker - check for the ecryptfs marker | |
961 | * @data: The data block in which to check | |
962 | * | |
963 | * Returns one if marker found; zero if not found | |
964 | */ | |
965 | int contains_ecryptfs_marker(char *data) | |
966 | { | |
967 | u32 m_1, m_2; | |
968 | ||
969 | memcpy(&m_1, data, 4); | |
970 | m_1 = be32_to_cpu(m_1); | |
971 | memcpy(&m_2, (data + 4), 4); | |
972 | m_2 = be32_to_cpu(m_2); | |
973 | if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2) | |
974 | return 1; | |
975 | ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; " | |
976 | "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2, | |
977 | MAGIC_ECRYPTFS_MARKER); | |
978 | ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = " | |
979 | "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER)); | |
980 | return 0; | |
981 | } | |
982 | ||
983 | struct ecryptfs_flag_map_elem { | |
984 | u32 file_flag; | |
985 | u32 local_flag; | |
986 | }; | |
987 | ||
988 | /* Add support for additional flags by adding elements here. */ | |
989 | static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = { | |
990 | {0x00000001, ECRYPTFS_ENABLE_HMAC}, | |
991 | {0x00000002, ECRYPTFS_ENCRYPTED} | |
992 | }; | |
993 | ||
994 | /** | |
995 | * ecryptfs_process_flags | |
996 | * @crypt_stat | |
997 | * @page_virt: Source data to be parsed | |
998 | * @bytes_read: Updated with the number of bytes read | |
999 | * | |
1000 | * Returns zero on success; non-zero if the flag set is invalid | |
1001 | */ | |
1002 | static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat, | |
1003 | char *page_virt, int *bytes_read) | |
1004 | { | |
1005 | int rc = 0; | |
1006 | int i; | |
1007 | u32 flags; | |
1008 | ||
1009 | memcpy(&flags, page_virt, 4); | |
1010 | flags = be32_to_cpu(flags); | |
1011 | for (i = 0; i < ((sizeof(ecryptfs_flag_map) | |
1012 | / sizeof(struct ecryptfs_flag_map_elem))); i++) | |
1013 | if (flags & ecryptfs_flag_map[i].file_flag) { | |
1014 | ECRYPTFS_SET_FLAG(crypt_stat->flags, | |
1015 | ecryptfs_flag_map[i].local_flag); | |
1016 | } else | |
1017 | ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, | |
1018 | ecryptfs_flag_map[i].local_flag); | |
1019 | /* Version is in top 8 bits of the 32-bit flag vector */ | |
1020 | crypt_stat->file_version = ((flags >> 24) & 0xFF); | |
1021 | (*bytes_read) = 4; | |
1022 | return rc; | |
1023 | } | |
1024 | ||
1025 | /** | |
1026 | * write_ecryptfs_marker | |
1027 | * @page_virt: The pointer to in a page to begin writing the marker | |
1028 | * @written: Number of bytes written | |
1029 | * | |
1030 | * Marker = 0x3c81b7f5 | |
1031 | */ | |
1032 | static void write_ecryptfs_marker(char *page_virt, size_t *written) | |
1033 | { | |
1034 | u32 m_1, m_2; | |
1035 | ||
1036 | get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); | |
1037 | m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER); | |
1038 | m_1 = cpu_to_be32(m_1); | |
1039 | memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); | |
1040 | m_2 = cpu_to_be32(m_2); | |
1041 | memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2, | |
1042 | (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); | |
1043 | (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; | |
1044 | } | |
1045 | ||
1046 | static void | |
1047 | write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat, | |
1048 | size_t *written) | |
1049 | { | |
1050 | u32 flags = 0; | |
1051 | int i; | |
1052 | ||
1053 | for (i = 0; i < ((sizeof(ecryptfs_flag_map) | |
1054 | / sizeof(struct ecryptfs_flag_map_elem))); i++) | |
1055 | if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
1056 | ecryptfs_flag_map[i].local_flag)) | |
1057 | flags |= ecryptfs_flag_map[i].file_flag; | |
1058 | /* Version is in top 8 bits of the 32-bit flag vector */ | |
1059 | flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000); | |
1060 | flags = cpu_to_be32(flags); | |
1061 | memcpy(page_virt, &flags, 4); | |
1062 | (*written) = 4; | |
1063 | } | |
1064 | ||
1065 | struct ecryptfs_cipher_code_str_map_elem { | |
1066 | char cipher_str[16]; | |
1067 | u16 cipher_code; | |
1068 | }; | |
1069 | ||
1070 | /* Add support for additional ciphers by adding elements here. The | |
1071 | * cipher_code is whatever OpenPGP applicatoins use to identify the | |
1072 | * ciphers. List in order of probability. */ | |
1073 | static struct ecryptfs_cipher_code_str_map_elem | |
1074 | ecryptfs_cipher_code_str_map[] = { | |
1075 | {"aes",RFC2440_CIPHER_AES_128 }, | |
1076 | {"blowfish", RFC2440_CIPHER_BLOWFISH}, | |
1077 | {"des3_ede", RFC2440_CIPHER_DES3_EDE}, | |
1078 | {"cast5", RFC2440_CIPHER_CAST_5}, | |
1079 | {"twofish", RFC2440_CIPHER_TWOFISH}, | |
1080 | {"cast6", RFC2440_CIPHER_CAST_6}, | |
1081 | {"aes", RFC2440_CIPHER_AES_192}, | |
1082 | {"aes", RFC2440_CIPHER_AES_256} | |
1083 | }; | |
1084 | ||
1085 | /** | |
1086 | * ecryptfs_code_for_cipher_string | |
1087 | * @str: The string representing the cipher name | |
1088 | * | |
1089 | * Returns zero on no match, or the cipher code on match | |
1090 | */ | |
1091 | u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat) | |
1092 | { | |
1093 | int i; | |
1094 | u16 code = 0; | |
1095 | struct ecryptfs_cipher_code_str_map_elem *map = | |
1096 | ecryptfs_cipher_code_str_map; | |
1097 | ||
1098 | if (strcmp(crypt_stat->cipher, "aes") == 0) { | |
1099 | switch (crypt_stat->key_size) { | |
1100 | case 16: | |
1101 | code = RFC2440_CIPHER_AES_128; | |
1102 | break; | |
1103 | case 24: | |
1104 | code = RFC2440_CIPHER_AES_192; | |
1105 | break; | |
1106 | case 32: | |
1107 | code = RFC2440_CIPHER_AES_256; | |
1108 | } | |
1109 | } else { | |
1110 | for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) | |
1111 | if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){ | |
1112 | code = map[i].cipher_code; | |
1113 | break; | |
1114 | } | |
1115 | } | |
1116 | return code; | |
1117 | } | |
1118 | ||
1119 | /** | |
1120 | * ecryptfs_cipher_code_to_string | |
1121 | * @str: Destination to write out the cipher name | |
1122 | * @cipher_code: The code to convert to cipher name string | |
1123 | * | |
1124 | * Returns zero on success | |
1125 | */ | |
1126 | int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code) | |
1127 | { | |
1128 | int rc = 0; | |
1129 | int i; | |
1130 | ||
1131 | str[0] = '\0'; | |
1132 | for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) | |
1133 | if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code) | |
1134 | strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str); | |
1135 | if (str[0] == '\0') { | |
1136 | ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: " | |
1137 | "[%d]\n", cipher_code); | |
1138 | rc = -EINVAL; | |
1139 | } | |
1140 | return rc; | |
1141 | } | |
1142 | ||
1143 | /** | |
1144 | * ecryptfs_read_header_region | |
1145 | * @data | |
1146 | * @dentry | |
1147 | * @nd | |
1148 | * | |
1149 | * Returns zero on success; non-zero otherwise | |
1150 | */ | |
1151 | int ecryptfs_read_header_region(char *data, struct dentry *dentry, | |
1152 | struct vfsmount *mnt) | |
1153 | { | |
1154 | struct file *file; | |
1155 | mm_segment_t oldfs; | |
1156 | int rc; | |
1157 | ||
1158 | mnt = mntget(mnt); | |
1159 | file = dentry_open(dentry, mnt, O_RDONLY); | |
1160 | if (IS_ERR(file)) { | |
1161 | ecryptfs_printk(KERN_DEBUG, "Error opening file to " | |
1162 | "read header region\n"); | |
1163 | mntput(mnt); | |
1164 | rc = PTR_ERR(file); | |
1165 | goto out; | |
1166 | } | |
1167 | file->f_pos = 0; | |
1168 | oldfs = get_fs(); | |
1169 | set_fs(get_ds()); | |
1170 | /* For releases 0.1 and 0.2, all of the header information | |
1171 | * fits in the first data extent-sized region. */ | |
1172 | rc = file->f_op->read(file, (char __user *)data, | |
1173 | ECRYPTFS_DEFAULT_EXTENT_SIZE, &file->f_pos); | |
1174 | set_fs(oldfs); | |
1175 | fput(file); | |
1176 | rc = 0; | |
1177 | out: | |
1178 | return rc; | |
1179 | } | |
1180 | ||
1181 | static void | |
1182 | write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat, | |
1183 | size_t *written) | |
1184 | { | |
1185 | u32 header_extent_size; | |
1186 | u16 num_header_extents_at_front; | |
1187 | ||
1188 | header_extent_size = (u32)crypt_stat->header_extent_size; | |
1189 | num_header_extents_at_front = | |
1190 | (u16)crypt_stat->num_header_extents_at_front; | |
1191 | header_extent_size = cpu_to_be32(header_extent_size); | |
1192 | memcpy(virt, &header_extent_size, 4); | |
1193 | virt += 4; | |
1194 | num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front); | |
1195 | memcpy(virt, &num_header_extents_at_front, 2); | |
1196 | (*written) = 6; | |
1197 | } | |
1198 | ||
1199 | struct kmem_cache *ecryptfs_header_cache_0; | |
1200 | struct kmem_cache *ecryptfs_header_cache_1; | |
1201 | struct kmem_cache *ecryptfs_header_cache_2; | |
1202 | ||
1203 | /** | |
1204 | * ecryptfs_write_headers_virt | |
1205 | * @page_virt | |
1206 | * @crypt_stat | |
1207 | * @ecryptfs_dentry | |
1208 | * | |
1209 | * Format version: 1 | |
1210 | * | |
1211 | * Header Extent: | |
1212 | * Octets 0-7: Unencrypted file size (big-endian) | |
1213 | * Octets 8-15: eCryptfs special marker | |
1214 | * Octets 16-19: Flags | |
1215 | * Octet 16: File format version number (between 0 and 255) | |
1216 | * Octets 17-18: Reserved | |
1217 | * Octet 19: Bit 1 (lsb): Reserved | |
1218 | * Bit 2: Encrypted? | |
1219 | * Bits 3-8: Reserved | |
1220 | * Octets 20-23: Header extent size (big-endian) | |
1221 | * Octets 24-25: Number of header extents at front of file | |
1222 | * (big-endian) | |
1223 | * Octet 26: Begin RFC 2440 authentication token packet set | |
1224 | * Data Extent 0: | |
1225 | * Lower data (CBC encrypted) | |
1226 | * Data Extent 1: | |
1227 | * Lower data (CBC encrypted) | |
1228 | * ... | |
1229 | * | |
1230 | * Returns zero on success | |
1231 | */ | |
1232 | int ecryptfs_write_headers_virt(char *page_virt, | |
1233 | struct ecryptfs_crypt_stat *crypt_stat, | |
1234 | struct dentry *ecryptfs_dentry) | |
1235 | { | |
1236 | int rc; | |
1237 | size_t written; | |
1238 | size_t offset; | |
1239 | ||
1240 | offset = ECRYPTFS_FILE_SIZE_BYTES; | |
1241 | write_ecryptfs_marker((page_virt + offset), &written); | |
1242 | offset += written; | |
1243 | write_ecryptfs_flags((page_virt + offset), crypt_stat, &written); | |
1244 | offset += written; | |
1245 | write_header_metadata((page_virt + offset), crypt_stat, &written); | |
1246 | offset += written; | |
1247 | rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat, | |
1248 | ecryptfs_dentry, &written, | |
1249 | PAGE_CACHE_SIZE - offset); | |
1250 | if (rc) | |
1251 | ecryptfs_printk(KERN_WARNING, "Error generating key packet " | |
1252 | "set; rc = [%d]\n", rc); | |
1253 | return rc; | |
1254 | } | |
1255 | ||
1256 | /** | |
1257 | * ecryptfs_write_headers | |
1258 | * @lower_file: The lower file struct, which was returned from dentry_open | |
1259 | * | |
1260 | * Write the file headers out. This will likely involve a userspace | |
1261 | * callout, in which the session key is encrypted with one or more | |
1262 | * public keys and/or the passphrase necessary to do the encryption is | |
1263 | * retrieved via a prompt. Exactly what happens at this point should | |
1264 | * be policy-dependent. | |
1265 | * | |
1266 | * Returns zero on success; non-zero on error | |
1267 | */ | |
1268 | int ecryptfs_write_headers(struct dentry *ecryptfs_dentry, | |
1269 | struct file *lower_file) | |
1270 | { | |
1271 | mm_segment_t oldfs; | |
1272 | struct ecryptfs_crypt_stat *crypt_stat; | |
1273 | char *page_virt; | |
1274 | int current_header_page; | |
1275 | int header_pages; | |
1276 | int rc = 0; | |
1277 | ||
1278 | crypt_stat = &ecryptfs_inode_to_private( | |
1279 | ecryptfs_dentry->d_inode)->crypt_stat; | |
1280 | if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
1281 | ECRYPTFS_ENCRYPTED))) { | |
1282 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
1283 | ECRYPTFS_KEY_VALID)) { | |
1284 | ecryptfs_printk(KERN_DEBUG, "Key is " | |
1285 | "invalid; bailing out\n"); | |
1286 | rc = -EINVAL; | |
1287 | goto out; | |
1288 | } | |
1289 | } else { | |
1290 | rc = -EINVAL; | |
1291 | ecryptfs_printk(KERN_WARNING, | |
1292 | "Called with crypt_stat->encrypted == 0\n"); | |
1293 | goto out; | |
1294 | } | |
1295 | /* Released in this function */ | |
1296 | page_virt = kmem_cache_alloc(ecryptfs_header_cache_0, SLAB_USER); | |
1297 | if (!page_virt) { | |
1298 | ecryptfs_printk(KERN_ERR, "Out of memory\n"); | |
1299 | rc = -ENOMEM; | |
1300 | goto out; | |
1301 | } | |
1302 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1303 | rc = ecryptfs_write_headers_virt(page_virt, crypt_stat, | |
1304 | ecryptfs_dentry); | |
1305 | if (unlikely(rc)) { | |
1306 | ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n"); | |
1307 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1308 | goto out_free; | |
1309 | } | |
1310 | ecryptfs_printk(KERN_DEBUG, | |
1311 | "Writing key packet set to underlying file\n"); | |
1312 | lower_file->f_pos = 0; | |
1313 | oldfs = get_fs(); | |
1314 | set_fs(get_ds()); | |
1315 | ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->" | |
1316 | "write() w/ header page; lower_file->f_pos = " | |
1317 | "[0x%.16x]\n", lower_file->f_pos); | |
1318 | lower_file->f_op->write(lower_file, (char __user *)page_virt, | |
1319 | PAGE_CACHE_SIZE, &lower_file->f_pos); | |
1320 | header_pages = ((crypt_stat->header_extent_size | |
1321 | * crypt_stat->num_header_extents_at_front) | |
1322 | / PAGE_CACHE_SIZE); | |
1323 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1324 | current_header_page = 1; | |
1325 | while (current_header_page < header_pages) { | |
1326 | ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->" | |
1327 | "write() w/ zero'd page; lower_file->f_pos = " | |
1328 | "[0x%.16x]\n", lower_file->f_pos); | |
1329 | lower_file->f_op->write(lower_file, (char __user *)page_virt, | |
1330 | PAGE_CACHE_SIZE, &lower_file->f_pos); | |
1331 | current_header_page++; | |
1332 | } | |
1333 | set_fs(oldfs); | |
1334 | ecryptfs_printk(KERN_DEBUG, | |
1335 | "Done writing key packet set to underlying file.\n"); | |
1336 | out_free: | |
1337 | kmem_cache_free(ecryptfs_header_cache_0, page_virt); | |
1338 | out: | |
1339 | return rc; | |
1340 | } | |
1341 | ||
1342 | static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat, | |
1343 | char *virt, int *bytes_read) | |
1344 | { | |
1345 | int rc = 0; | |
1346 | u32 header_extent_size; | |
1347 | u16 num_header_extents_at_front; | |
1348 | ||
1349 | memcpy(&header_extent_size, virt, 4); | |
1350 | header_extent_size = be32_to_cpu(header_extent_size); | |
1351 | virt += 4; | |
1352 | memcpy(&num_header_extents_at_front, virt, 2); | |
1353 | num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front); | |
1354 | crypt_stat->header_extent_size = (int)header_extent_size; | |
1355 | crypt_stat->num_header_extents_at_front = | |
1356 | (int)num_header_extents_at_front; | |
1357 | (*bytes_read) = 6; | |
1358 | if ((crypt_stat->header_extent_size | |
1359 | * crypt_stat->num_header_extents_at_front) | |
1360 | < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) { | |
1361 | rc = -EINVAL; | |
1362 | ecryptfs_printk(KERN_WARNING, "Invalid header extent size: " | |
1363 | "[%d]\n", crypt_stat->header_extent_size); | |
1364 | } | |
1365 | return rc; | |
1366 | } | |
1367 | ||
1368 | /** | |
1369 | * set_default_header_data | |
1370 | * | |
1371 | * For version 0 file format; this function is only for backwards | |
1372 | * compatibility for files created with the prior versions of | |
1373 | * eCryptfs. | |
1374 | */ | |
1375 | static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat) | |
1376 | { | |
1377 | crypt_stat->header_extent_size = 4096; | |
1378 | crypt_stat->num_header_extents_at_front = 1; | |
1379 | } | |
1380 | ||
1381 | /** | |
1382 | * ecryptfs_read_headers_virt | |
1383 | * | |
1384 | * Read/parse the header data. The header format is detailed in the | |
1385 | * comment block for the ecryptfs_write_headers_virt() function. | |
1386 | * | |
1387 | * Returns zero on success | |
1388 | */ | |
1389 | static int ecryptfs_read_headers_virt(char *page_virt, | |
1390 | struct ecryptfs_crypt_stat *crypt_stat, | |
1391 | struct dentry *ecryptfs_dentry) | |
1392 | { | |
1393 | int rc = 0; | |
1394 | int offset; | |
1395 | int bytes_read; | |
1396 | ||
1397 | ecryptfs_set_default_sizes(crypt_stat); | |
1398 | crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private( | |
1399 | ecryptfs_dentry->d_sb)->mount_crypt_stat; | |
1400 | offset = ECRYPTFS_FILE_SIZE_BYTES; | |
1401 | rc = contains_ecryptfs_marker(page_virt + offset); | |
1402 | if (rc == 0) { | |
1403 | rc = -EINVAL; | |
1404 | goto out; | |
1405 | } | |
1406 | offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; | |
1407 | rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset), | |
1408 | &bytes_read); | |
1409 | if (rc) { | |
1410 | ecryptfs_printk(KERN_WARNING, "Error processing flags\n"); | |
1411 | goto out; | |
1412 | } | |
1413 | if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) { | |
1414 | ecryptfs_printk(KERN_WARNING, "File version is [%d]; only " | |
1415 | "file version [%d] is supported by this " | |
1416 | "version of eCryptfs\n", | |
1417 | crypt_stat->file_version, | |
1418 | ECRYPTFS_SUPPORTED_FILE_VERSION); | |
1419 | rc = -EINVAL; | |
1420 | goto out; | |
1421 | } | |
1422 | offset += bytes_read; | |
1423 | if (crypt_stat->file_version >= 1) { | |
1424 | rc = parse_header_metadata(crypt_stat, (page_virt + offset), | |
1425 | &bytes_read); | |
1426 | if (rc) { | |
1427 | ecryptfs_printk(KERN_WARNING, "Error reading header " | |
1428 | "metadata; rc = [%d]\n", rc); | |
1429 | } | |
1430 | offset += bytes_read; | |
1431 | } else | |
1432 | set_default_header_data(crypt_stat); | |
1433 | rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset), | |
1434 | ecryptfs_dentry); | |
1435 | out: | |
1436 | return rc; | |
1437 | } | |
1438 | ||
1439 | /** | |
1440 | * ecryptfs_read_headers | |
1441 | * | |
1442 | * Returns zero if valid headers found and parsed; non-zero otherwise | |
1443 | */ | |
1444 | int ecryptfs_read_headers(struct dentry *ecryptfs_dentry, | |
1445 | struct file *lower_file) | |
1446 | { | |
1447 | int rc = 0; | |
1448 | char *page_virt = NULL; | |
1449 | mm_segment_t oldfs; | |
1450 | ssize_t bytes_read; | |
1451 | struct ecryptfs_crypt_stat *crypt_stat = | |
1452 | &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat; | |
1453 | ||
1454 | /* Read the first page from the underlying file */ | |
1455 | page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_USER); | |
1456 | if (!page_virt) { | |
1457 | rc = -ENOMEM; | |
1458 | ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n"); | |
1459 | goto out; | |
1460 | } | |
1461 | lower_file->f_pos = 0; | |
1462 | oldfs = get_fs(); | |
1463 | set_fs(get_ds()); | |
1464 | bytes_read = lower_file->f_op->read(lower_file, | |
1465 | (char __user *)page_virt, | |
1466 | ECRYPTFS_DEFAULT_EXTENT_SIZE, | |
1467 | &lower_file->f_pos); | |
1468 | set_fs(oldfs); | |
1469 | if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) { | |
1470 | rc = -EINVAL; | |
1471 | goto out; | |
1472 | } | |
1473 | rc = ecryptfs_read_headers_virt(page_virt, crypt_stat, | |
1474 | ecryptfs_dentry); | |
1475 | if (rc) { | |
1476 | ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not " | |
1477 | "found\n"); | |
1478 | rc = -EINVAL; | |
1479 | } | |
1480 | out: | |
1481 | if (page_virt) { | |
1482 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1483 | kmem_cache_free(ecryptfs_header_cache_1, page_virt); | |
1484 | } | |
1485 | return rc; | |
1486 | } | |
1487 | ||
1488 | /** | |
1489 | * ecryptfs_encode_filename - converts a plaintext file name to cipher text | |
1490 | * @crypt_stat: The crypt_stat struct associated with the file anem to encode | |
1491 | * @name: The plaintext name | |
1492 | * @length: The length of the plaintext | |
1493 | * @encoded_name: The encypted name | |
1494 | * | |
1495 | * Encrypts and encodes a filename into something that constitutes a | |
1496 | * valid filename for a filesystem, with printable characters. | |
1497 | * | |
1498 | * We assume that we have a properly initialized crypto context, | |
1499 | * pointed to by crypt_stat->tfm. | |
1500 | * | |
1501 | * TODO: Implement filename decoding and decryption here, in place of | |
1502 | * memcpy. We are keeping the framework around for now to (1) | |
1503 | * facilitate testing of the components needed to implement filename | |
1504 | * encryption and (2) to provide a code base from which other | |
1505 | * developers in the community can easily implement this feature. | |
1506 | * | |
1507 | * Returns the length of encoded filename; negative if error | |
1508 | */ | |
1509 | int | |
1510 | ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat, | |
1511 | const char *name, int length, char **encoded_name) | |
1512 | { | |
1513 | int error = 0; | |
1514 | ||
1515 | (*encoded_name) = kmalloc(length + 2, GFP_KERNEL); | |
1516 | if (!(*encoded_name)) { | |
1517 | error = -ENOMEM; | |
1518 | goto out; | |
1519 | } | |
1520 | /* TODO: Filename encryption is a scheduled feature for a | |
1521 | * future version of eCryptfs. This function is here only for | |
1522 | * the purpose of providing a framework for other developers | |
1523 | * to easily implement filename encryption. Hint: Replace this | |
1524 | * memcpy() with a call to encrypt and encode the | |
1525 | * filename, the set the length accordingly. */ | |
1526 | memcpy((void *)(*encoded_name), (void *)name, length); | |
1527 | (*encoded_name)[length] = '\0'; | |
1528 | error = length + 1; | |
1529 | out: | |
1530 | return error; | |
1531 | } | |
1532 | ||
1533 | /** | |
1534 | * ecryptfs_decode_filename - converts the cipher text name to plaintext | |
1535 | * @crypt_stat: The crypt_stat struct associated with the file | |
1536 | * @name: The filename in cipher text | |
1537 | * @length: The length of the cipher text name | |
1538 | * @decrypted_name: The plaintext name | |
1539 | * | |
1540 | * Decodes and decrypts the filename. | |
1541 | * | |
1542 | * We assume that we have a properly initialized crypto context, | |
1543 | * pointed to by crypt_stat->tfm. | |
1544 | * | |
1545 | * TODO: Implement filename decoding and decryption here, in place of | |
1546 | * memcpy. We are keeping the framework around for now to (1) | |
1547 | * facilitate testing of the components needed to implement filename | |
1548 | * encryption and (2) to provide a code base from which other | |
1549 | * developers in the community can easily implement this feature. | |
1550 | * | |
1551 | * Returns the length of decoded filename; negative if error | |
1552 | */ | |
1553 | int | |
1554 | ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat, | |
1555 | const char *name, int length, char **decrypted_name) | |
1556 | { | |
1557 | int error = 0; | |
1558 | ||
1559 | (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL); | |
1560 | if (!(*decrypted_name)) { | |
1561 | error = -ENOMEM; | |
1562 | goto out; | |
1563 | } | |
1564 | /* TODO: Filename encryption is a scheduled feature for a | |
1565 | * future version of eCryptfs. This function is here only for | |
1566 | * the purpose of providing a framework for other developers | |
1567 | * to easily implement filename encryption. Hint: Replace this | |
1568 | * memcpy() with a call to decode and decrypt the | |
1569 | * filename, the set the length accordingly. */ | |
1570 | memcpy((void *)(*decrypted_name), (void *)name, length); | |
1571 | (*decrypted_name)[length + 1] = '\0'; /* Only for convenience | |
1572 | * in printing out the | |
1573 | * string in debug | |
1574 | * messages */ | |
1575 | error = length; | |
1576 | out: | |
1577 | return error; | |
1578 | } | |
1579 | ||
1580 | /** | |
1581 | * ecryptfs_process_cipher - Perform cipher initialization. | |
237fead6 | 1582 | * @key_tfm: Crypto context for key material, set by this function |
e5d9cbde MH |
1583 | * @cipher_name: Name of the cipher |
1584 | * @key_size: Size of the key in bytes | |
237fead6 MH |
1585 | * |
1586 | * Returns zero on success. Any crypto_tfm structs allocated here | |
1587 | * should be released by other functions, such as on a superblock put | |
1588 | * event, regardless of whether this function succeeds for fails. | |
1589 | */ | |
1590 | int | |
e5d9cbde MH |
1591 | ecryptfs_process_cipher(struct crypto_tfm **key_tfm, char *cipher_name, |
1592 | size_t *key_size) | |
237fead6 MH |
1593 | { |
1594 | char dummy_key[ECRYPTFS_MAX_KEY_BYTES]; | |
1595 | int rc; | |
1596 | ||
e5d9cbde MH |
1597 | *key_tfm = NULL; |
1598 | if (*key_size > ECRYPTFS_MAX_KEY_BYTES) { | |
237fead6 MH |
1599 | rc = -EINVAL; |
1600 | printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum " | |
e5d9cbde | 1601 | "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES); |
237fead6 MH |
1602 | goto out; |
1603 | } | |
1604 | *key_tfm = crypto_alloc_tfm(cipher_name, CRYPTO_TFM_REQ_WEAK_KEY); | |
1605 | if (!(*key_tfm)) { | |
1606 | rc = -EINVAL; | |
1607 | printk(KERN_ERR "Unable to allocate crypto cipher with name " | |
1608 | "[%s]\n", cipher_name); | |
1609 | goto out; | |
1610 | } | |
e5d9cbde MH |
1611 | if (*key_size == 0) |
1612 | *key_size = crypto_tfm_alg_max_keysize(*key_tfm); | |
1613 | get_random_bytes(dummy_key, *key_size); | |
1614 | rc = crypto_cipher_setkey(*key_tfm, dummy_key, *key_size); | |
237fead6 MH |
1615 | if (rc) { |
1616 | printk(KERN_ERR "Error attempting to set key of size [%Zd] for " | |
e5d9cbde | 1617 | "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc); |
237fead6 MH |
1618 | rc = -EINVAL; |
1619 | goto out; | |
1620 | } | |
1621 | out: | |
1622 | return rc; | |
1623 | } |