Commit | Line | Data |
---|---|---|
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 | { | |
97 | int rc = 0; | |
98 | struct scatterlist sg; | |
99 | ||
100 | mutex_lock(&crypt_stat->cs_md5_tfm_mutex); | |
101 | sg_init_one(&sg, (u8 *)src, len); | |
102 | if (!crypt_stat->md5_tfm) { | |
103 | crypt_stat->md5_tfm = | |
104 | crypto_alloc_tfm("md5", CRYPTO_TFM_REQ_MAY_SLEEP); | |
105 | if (!crypt_stat->md5_tfm) { | |
106 | rc = -ENOMEM; | |
107 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
108 | "allocate crypto context\n"); | |
109 | goto out; | |
110 | } | |
111 | } | |
112 | crypto_digest_init(crypt_stat->md5_tfm); | |
113 | crypto_digest_update(crypt_stat->md5_tfm, &sg, 1); | |
114 | crypto_digest_final(crypt_stat->md5_tfm, dst); | |
115 | mutex_unlock(&crypt_stat->cs_md5_tfm_mutex); | |
116 | out: | |
117 | return rc; | |
118 | } | |
119 | ||
120 | /** | |
121 | * ecryptfs_derive_iv | |
122 | * @iv: destination for the derived iv vale | |
123 | * @crypt_stat: Pointer to crypt_stat struct for the current inode | |
124 | * @offset: Offset of the page whose's iv we are to derive | |
125 | * | |
126 | * Generate the initialization vector from the given root IV and page | |
127 | * offset. | |
128 | * | |
129 | * Returns zero on success; non-zero on error. | |
130 | */ | |
131 | static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat, | |
132 | pgoff_t offset) | |
133 | { | |
134 | int rc = 0; | |
135 | char dst[MD5_DIGEST_SIZE]; | |
136 | char src[ECRYPTFS_MAX_IV_BYTES + 16]; | |
137 | ||
138 | if (unlikely(ecryptfs_verbosity > 0)) { | |
139 | ecryptfs_printk(KERN_DEBUG, "root iv:\n"); | |
140 | ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes); | |
141 | } | |
142 | /* TODO: It is probably secure to just cast the least | |
143 | * significant bits of the root IV into an unsigned long and | |
144 | * add the offset to that rather than go through all this | |
145 | * hashing business. -Halcrow */ | |
146 | memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes); | |
147 | memset((src + crypt_stat->iv_bytes), 0, 16); | |
148 | snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset); | |
149 | if (unlikely(ecryptfs_verbosity > 0)) { | |
150 | ecryptfs_printk(KERN_DEBUG, "source:\n"); | |
151 | ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16)); | |
152 | } | |
153 | rc = ecryptfs_calculate_md5(dst, crypt_stat, src, | |
154 | (crypt_stat->iv_bytes + 16)); | |
155 | if (rc) { | |
156 | ecryptfs_printk(KERN_WARNING, "Error attempting to compute " | |
157 | "MD5 while generating IV for a page\n"); | |
158 | goto out; | |
159 | } | |
160 | memcpy(iv, dst, crypt_stat->iv_bytes); | |
161 | if (unlikely(ecryptfs_verbosity > 0)) { | |
162 | ecryptfs_printk(KERN_DEBUG, "derived iv:\n"); | |
163 | ecryptfs_dump_hex(iv, crypt_stat->iv_bytes); | |
164 | } | |
165 | out: | |
166 | return rc; | |
167 | } | |
168 | ||
169 | /** | |
170 | * ecryptfs_init_crypt_stat | |
171 | * @crypt_stat: Pointer to the crypt_stat struct to initialize. | |
172 | * | |
173 | * Initialize the crypt_stat structure. | |
174 | */ | |
175 | void | |
176 | ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) | |
177 | { | |
178 | memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); | |
179 | mutex_init(&crypt_stat->cs_mutex); | |
180 | mutex_init(&crypt_stat->cs_tfm_mutex); | |
181 | mutex_init(&crypt_stat->cs_md5_tfm_mutex); | |
182 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED); | |
183 | } | |
184 | ||
185 | /** | |
186 | * ecryptfs_destruct_crypt_stat | |
187 | * @crypt_stat: Pointer to the crypt_stat struct to initialize. | |
188 | * | |
189 | * Releases all memory associated with a crypt_stat struct. | |
190 | */ | |
191 | void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) | |
192 | { | |
193 | if (crypt_stat->tfm) | |
194 | crypto_free_tfm(crypt_stat->tfm); | |
195 | if (crypt_stat->md5_tfm) | |
196 | crypto_free_tfm(crypt_stat->md5_tfm); | |
197 | memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); | |
198 | } | |
199 | ||
200 | void ecryptfs_destruct_mount_crypt_stat( | |
201 | struct ecryptfs_mount_crypt_stat *mount_crypt_stat) | |
202 | { | |
203 | if (mount_crypt_stat->global_auth_tok_key) | |
204 | key_put(mount_crypt_stat->global_auth_tok_key); | |
205 | if (mount_crypt_stat->global_key_tfm) | |
206 | crypto_free_tfm(mount_crypt_stat->global_key_tfm); | |
207 | memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat)); | |
208 | } | |
209 | ||
210 | /** | |
211 | * virt_to_scatterlist | |
212 | * @addr: Virtual address | |
213 | * @size: Size of data; should be an even multiple of the block size | |
214 | * @sg: Pointer to scatterlist array; set to NULL to obtain only | |
215 | * the number of scatterlist structs required in array | |
216 | * @sg_size: Max array size | |
217 | * | |
218 | * Fills in a scatterlist array with page references for a passed | |
219 | * virtual address. | |
220 | * | |
221 | * Returns the number of scatterlist structs in array used | |
222 | */ | |
223 | int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg, | |
224 | int sg_size) | |
225 | { | |
226 | int i = 0; | |
227 | struct page *pg; | |
228 | int offset; | |
229 | int remainder_of_page; | |
230 | ||
231 | while (size > 0 && i < sg_size) { | |
232 | pg = virt_to_page(addr); | |
233 | offset = offset_in_page(addr); | |
234 | if (sg) { | |
235 | sg[i].page = pg; | |
236 | sg[i].offset = offset; | |
237 | } | |
238 | remainder_of_page = PAGE_CACHE_SIZE - offset; | |
239 | if (size >= remainder_of_page) { | |
240 | if (sg) | |
241 | sg[i].length = remainder_of_page; | |
242 | addr += remainder_of_page; | |
243 | size -= remainder_of_page; | |
244 | } else { | |
245 | if (sg) | |
246 | sg[i].length = size; | |
247 | addr += size; | |
248 | size = 0; | |
249 | } | |
250 | i++; | |
251 | } | |
252 | if (size > 0) | |
253 | return -ENOMEM; | |
254 | return i; | |
255 | } | |
256 | ||
257 | /** | |
258 | * encrypt_scatterlist | |
259 | * @crypt_stat: Pointer to the crypt_stat struct to initialize. | |
260 | * @dest_sg: Destination of encrypted data | |
261 | * @src_sg: Data to be encrypted | |
262 | * @size: Length of data to be encrypted | |
263 | * @iv: iv to use during encryption | |
264 | * | |
265 | * Returns the number of bytes encrypted; negative value on error | |
266 | */ | |
267 | static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, | |
268 | struct scatterlist *dest_sg, | |
269 | struct scatterlist *src_sg, int size, | |
270 | unsigned char *iv) | |
271 | { | |
272 | int rc = 0; | |
273 | ||
274 | BUG_ON(!crypt_stat || !crypt_stat->tfm | |
275 | || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
276 | ECRYPTFS_STRUCT_INITIALIZED)); | |
277 | if (unlikely(ecryptfs_verbosity > 0)) { | |
278 | ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n", | |
279 | crypt_stat->key_size); | |
280 | ecryptfs_dump_hex(crypt_stat->key, | |
281 | crypt_stat->key_size); | |
282 | } | |
283 | /* Consider doing this once, when the file is opened */ | |
284 | mutex_lock(&crypt_stat->cs_tfm_mutex); | |
285 | rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key, | |
286 | crypt_stat->key_size); | |
287 | if (rc) { | |
288 | ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n", | |
289 | rc); | |
290 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
291 | rc = -EINVAL; | |
292 | goto out; | |
293 | } | |
294 | ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size); | |
295 | crypto_cipher_encrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, iv); | |
296 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
297 | out: | |
298 | return rc; | |
299 | } | |
300 | ||
301 | static void | |
302 | ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx, | |
303 | int *byte_offset, | |
304 | struct ecryptfs_crypt_stat *crypt_stat, | |
305 | unsigned long extent_num) | |
306 | { | |
307 | unsigned long lower_extent_num; | |
308 | int extents_occupied_by_headers_at_front; | |
309 | int bytes_occupied_by_headers_at_front; | |
310 | int extent_offset; | |
311 | int extents_per_page; | |
312 | ||
313 | bytes_occupied_by_headers_at_front = | |
314 | ( crypt_stat->header_extent_size | |
315 | * crypt_stat->num_header_extents_at_front ); | |
316 | extents_occupied_by_headers_at_front = | |
317 | ( bytes_occupied_by_headers_at_front | |
318 | / crypt_stat->extent_size ); | |
319 | lower_extent_num = extents_occupied_by_headers_at_front + extent_num; | |
320 | extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; | |
321 | (*lower_page_idx) = lower_extent_num / extents_per_page; | |
322 | extent_offset = lower_extent_num % extents_per_page; | |
323 | (*byte_offset) = extent_offset * crypt_stat->extent_size; | |
324 | ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = " | |
325 | "[%d]\n", crypt_stat->header_extent_size); | |
326 | ecryptfs_printk(KERN_DEBUG, " * crypt_stat->" | |
327 | "num_header_extents_at_front = [%d]\n", | |
328 | crypt_stat->num_header_extents_at_front); | |
329 | ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_" | |
330 | "front = [%d]\n", extents_occupied_by_headers_at_front); | |
331 | ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n", | |
332 | lower_extent_num); | |
333 | ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n", | |
334 | extents_per_page); | |
335 | ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n", | |
336 | (*lower_page_idx)); | |
337 | ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n", | |
338 | extent_offset); | |
339 | ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n", | |
340 | (*byte_offset)); | |
341 | } | |
342 | ||
343 | static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx, | |
344 | struct page *lower_page, | |
345 | struct inode *lower_inode, | |
346 | int byte_offset_in_page, int bytes_to_write) | |
347 | { | |
348 | int rc = 0; | |
349 | ||
350 | if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) { | |
351 | rc = ecryptfs_commit_lower_page(lower_page, lower_inode, | |
352 | ctx->param.lower_file, | |
353 | byte_offset_in_page, | |
354 | bytes_to_write); | |
355 | if (rc) { | |
356 | ecryptfs_printk(KERN_ERR, "Error calling lower " | |
357 | "commit; rc = [%d]\n", rc); | |
358 | goto out; | |
359 | } | |
360 | } else { | |
361 | rc = ecryptfs_writepage_and_release_lower_page(lower_page, | |
362 | lower_inode, | |
363 | ctx->param.wbc); | |
364 | if (rc) { | |
365 | ecryptfs_printk(KERN_ERR, "Error calling lower " | |
366 | "writepage(); rc = [%d]\n", rc); | |
367 | goto out; | |
368 | } | |
369 | } | |
370 | out: | |
371 | return rc; | |
372 | } | |
373 | ||
374 | static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx, | |
375 | struct page **lower_page, | |
376 | struct inode *lower_inode, | |
377 | unsigned long lower_page_idx, | |
378 | int byte_offset_in_page) | |
379 | { | |
380 | int rc = 0; | |
381 | ||
382 | if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) { | |
383 | /* TODO: Limit this to only the data extents that are | |
384 | * needed */ | |
385 | rc = ecryptfs_get_lower_page(lower_page, lower_inode, | |
386 | ctx->param.lower_file, | |
387 | lower_page_idx, | |
388 | byte_offset_in_page, | |
389 | (PAGE_CACHE_SIZE | |
390 | - byte_offset_in_page)); | |
391 | if (rc) { | |
392 | ecryptfs_printk( | |
393 | KERN_ERR, "Error attempting to grab, map, " | |
394 | "and prepare_write lower page with index " | |
395 | "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc); | |
396 | goto out; | |
397 | } | |
398 | } else { | |
399 | rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, | |
400 | lower_inode, | |
401 | lower_page_idx); | |
402 | if (rc) { | |
403 | ecryptfs_printk( | |
404 | KERN_ERR, "Error attempting to grab and map " | |
405 | "lower page with index [0x%.16x]; rc = [%d]\n", | |
406 | lower_page_idx, rc); | |
407 | goto out; | |
408 | } | |
409 | } | |
410 | out: | |
411 | return rc; | |
412 | } | |
413 | ||
414 | /** | |
415 | * ecryptfs_encrypt_page | |
416 | * @ctx: The context of the page | |
417 | * | |
418 | * Encrypt an eCryptfs page. This is done on a per-extent basis. Note | |
419 | * that eCryptfs pages may straddle the lower pages -- for instance, | |
420 | * if the file was created on a machine with an 8K page size | |
421 | * (resulting in an 8K header), and then the file is copied onto a | |
422 | * host with a 32K page size, then when reading page 0 of the eCryptfs | |
423 | * file, 24K of page 0 of the lower file will be read and decrypted, | |
424 | * and then 8K of page 1 of the lower file will be read and decrypted. | |
425 | * | |
426 | * The actual operations performed on each page depends on the | |
427 | * contents of the ecryptfs_page_crypt_context struct. | |
428 | * | |
429 | * Returns zero on success; negative on error | |
430 | */ | |
431 | int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx) | |
432 | { | |
433 | char extent_iv[ECRYPTFS_MAX_IV_BYTES]; | |
434 | unsigned long base_extent; | |
435 | unsigned long extent_offset = 0; | |
436 | unsigned long lower_page_idx = 0; | |
437 | unsigned long prior_lower_page_idx = 0; | |
438 | struct page *lower_page; | |
439 | struct inode *lower_inode; | |
440 | struct ecryptfs_inode_info *inode_info; | |
441 | struct ecryptfs_crypt_stat *crypt_stat; | |
442 | int rc = 0; | |
443 | int lower_byte_offset = 0; | |
444 | int orig_byte_offset = 0; | |
445 | int num_extents_per_page; | |
446 | #define ECRYPTFS_PAGE_STATE_UNREAD 0 | |
447 | #define ECRYPTFS_PAGE_STATE_READ 1 | |
448 | #define ECRYPTFS_PAGE_STATE_MODIFIED 2 | |
449 | #define ECRYPTFS_PAGE_STATE_WRITTEN 3 | |
450 | int page_state; | |
451 | ||
452 | lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host); | |
453 | inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host); | |
454 | crypt_stat = &inode_info->crypt_stat; | |
455 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) { | |
456 | rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode, | |
457 | ctx->param.lower_file); | |
458 | if (rc) | |
459 | ecryptfs_printk(KERN_ERR, "Error attempting to copy " | |
460 | "page at index [0x%.16x]\n", | |
461 | ctx->page->index); | |
462 | goto out; | |
463 | } | |
464 | num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; | |
465 | base_extent = (ctx->page->index * num_extents_per_page); | |
466 | page_state = ECRYPTFS_PAGE_STATE_UNREAD; | |
467 | while (extent_offset < num_extents_per_page) { | |
468 | ecryptfs_extent_to_lwr_pg_idx_and_offset( | |
469 | &lower_page_idx, &lower_byte_offset, crypt_stat, | |
470 | (base_extent + extent_offset)); | |
471 | if (prior_lower_page_idx != lower_page_idx | |
472 | && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) { | |
473 | rc = ecryptfs_write_out_page(ctx, lower_page, | |
474 | lower_inode, | |
475 | orig_byte_offset, | |
476 | (PAGE_CACHE_SIZE | |
477 | - orig_byte_offset)); | |
478 | if (rc) { | |
479 | ecryptfs_printk(KERN_ERR, "Error attempting " | |
480 | "to write out page; rc = [%d]" | |
481 | "\n", rc); | |
482 | goto out; | |
483 | } | |
484 | page_state = ECRYPTFS_PAGE_STATE_WRITTEN; | |
485 | } | |
486 | if (page_state == ECRYPTFS_PAGE_STATE_UNREAD | |
487 | || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) { | |
488 | rc = ecryptfs_read_in_page(ctx, &lower_page, | |
489 | lower_inode, lower_page_idx, | |
490 | lower_byte_offset); | |
491 | if (rc) { | |
492 | ecryptfs_printk(KERN_ERR, "Error attempting " | |
493 | "to read in lower page with " | |
494 | "index [0x%.16x]; rc = [%d]\n", | |
495 | lower_page_idx, rc); | |
496 | goto out; | |
497 | } | |
498 | orig_byte_offset = lower_byte_offset; | |
499 | prior_lower_page_idx = lower_page_idx; | |
500 | page_state = ECRYPTFS_PAGE_STATE_READ; | |
501 | } | |
502 | BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED | |
503 | || page_state == ECRYPTFS_PAGE_STATE_READ)); | |
504 | rc = ecryptfs_derive_iv(extent_iv, crypt_stat, | |
505 | (base_extent + extent_offset)); | |
506 | if (rc) { | |
507 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
508 | "derive IV for extent [0x%.16x]; " | |
509 | "rc = [%d]\n", | |
510 | (base_extent + extent_offset), rc); | |
511 | goto out; | |
512 | } | |
513 | if (unlikely(ecryptfs_verbosity > 0)) { | |
514 | ecryptfs_printk(KERN_DEBUG, "Encrypting extent " | |
515 | "with iv:\n"); | |
516 | ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes); | |
517 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes before " | |
518 | "encryption:\n"); | |
519 | ecryptfs_dump_hex((char *) | |
520 | (page_address(ctx->page) | |
521 | + (extent_offset | |
522 | * crypt_stat->extent_size)), 8); | |
523 | } | |
524 | rc = ecryptfs_encrypt_page_offset( | |
525 | crypt_stat, lower_page, lower_byte_offset, ctx->page, | |
526 | (extent_offset * crypt_stat->extent_size), | |
527 | crypt_stat->extent_size, extent_iv); | |
528 | ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; " | |
529 | "rc = [%d]\n", | |
530 | (base_extent + extent_offset), rc); | |
531 | if (unlikely(ecryptfs_verbosity > 0)) { | |
532 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes after " | |
533 | "encryption:\n"); | |
534 | ecryptfs_dump_hex((char *)(page_address(lower_page) | |
535 | + lower_byte_offset), 8); | |
536 | } | |
537 | page_state = ECRYPTFS_PAGE_STATE_MODIFIED; | |
538 | extent_offset++; | |
539 | } | |
540 | BUG_ON(orig_byte_offset != 0); | |
541 | rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0, | |
542 | (lower_byte_offset | |
543 | + crypt_stat->extent_size)); | |
544 | if (rc) { | |
545 | ecryptfs_printk(KERN_ERR, "Error attempting to write out " | |
546 | "page; rc = [%d]\n", rc); | |
547 | goto out; | |
548 | } | |
549 | out: | |
550 | return rc; | |
551 | } | |
552 | ||
553 | /** | |
554 | * ecryptfs_decrypt_page | |
555 | * @file: The ecryptfs file | |
556 | * @page: The page in ecryptfs to decrypt | |
557 | * | |
558 | * Decrypt an eCryptfs page. This is done on a per-extent basis. Note | |
559 | * that eCryptfs pages may straddle the lower pages -- for instance, | |
560 | * if the file was created on a machine with an 8K page size | |
561 | * (resulting in an 8K header), and then the file is copied onto a | |
562 | * host with a 32K page size, then when reading page 0 of the eCryptfs | |
563 | * file, 24K of page 0 of the lower file will be read and decrypted, | |
564 | * and then 8K of page 1 of the lower file will be read and decrypted. | |
565 | * | |
566 | * Returns zero on success; negative on error | |
567 | */ | |
568 | int ecryptfs_decrypt_page(struct file *file, struct page *page) | |
569 | { | |
570 | char extent_iv[ECRYPTFS_MAX_IV_BYTES]; | |
571 | unsigned long base_extent; | |
572 | unsigned long extent_offset = 0; | |
573 | unsigned long lower_page_idx = 0; | |
574 | unsigned long prior_lower_page_idx = 0; | |
575 | struct page *lower_page; | |
576 | char *lower_page_virt = NULL; | |
577 | struct inode *lower_inode; | |
578 | struct ecryptfs_crypt_stat *crypt_stat; | |
579 | int rc = 0; | |
580 | int byte_offset; | |
581 | int num_extents_per_page; | |
582 | int page_state; | |
583 | ||
584 | crypt_stat = &(ecryptfs_inode_to_private( | |
585 | page->mapping->host)->crypt_stat); | |
586 | lower_inode = ecryptfs_inode_to_lower(page->mapping->host); | |
587 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) { | |
588 | rc = ecryptfs_do_readpage(file, page, page->index); | |
589 | if (rc) | |
590 | ecryptfs_printk(KERN_ERR, "Error attempting to copy " | |
591 | "page at index [0x%.16x]\n", | |
592 | page->index); | |
593 | goto out; | |
594 | } | |
595 | num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; | |
596 | base_extent = (page->index * num_extents_per_page); | |
597 | lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache, | |
598 | SLAB_KERNEL); | |
599 | if (!lower_page_virt) { | |
600 | rc = -ENOMEM; | |
601 | ecryptfs_printk(KERN_ERR, "Error getting page for encrypted " | |
602 | "lower page(s)\n"); | |
603 | goto out; | |
604 | } | |
605 | lower_page = virt_to_page(lower_page_virt); | |
606 | page_state = ECRYPTFS_PAGE_STATE_UNREAD; | |
607 | while (extent_offset < num_extents_per_page) { | |
608 | ecryptfs_extent_to_lwr_pg_idx_and_offset( | |
609 | &lower_page_idx, &byte_offset, crypt_stat, | |
610 | (base_extent + extent_offset)); | |
611 | if (prior_lower_page_idx != lower_page_idx | |
612 | || page_state == ECRYPTFS_PAGE_STATE_UNREAD) { | |
613 | rc = ecryptfs_do_readpage(file, lower_page, | |
614 | lower_page_idx); | |
615 | if (rc) { | |
616 | ecryptfs_printk(KERN_ERR, "Error reading " | |
617 | "lower encrypted page; rc = " | |
618 | "[%d]\n", rc); | |
619 | goto out; | |
620 | } | |
621 | prior_lower_page_idx = lower_page_idx; | |
622 | page_state = ECRYPTFS_PAGE_STATE_READ; | |
623 | } | |
624 | rc = ecryptfs_derive_iv(extent_iv, crypt_stat, | |
625 | (base_extent + extent_offset)); | |
626 | if (rc) { | |
627 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
628 | "derive IV for extent [0x%.16x]; rc = " | |
629 | "[%d]\n", | |
630 | (base_extent + extent_offset), rc); | |
631 | goto out; | |
632 | } | |
633 | if (unlikely(ecryptfs_verbosity > 0)) { | |
634 | ecryptfs_printk(KERN_DEBUG, "Decrypting extent " | |
635 | "with iv:\n"); | |
636 | ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes); | |
637 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes before " | |
638 | "decryption:\n"); | |
639 | ecryptfs_dump_hex((lower_page_virt + byte_offset), 8); | |
640 | } | |
641 | rc = ecryptfs_decrypt_page_offset(crypt_stat, page, | |
642 | (extent_offset | |
643 | * crypt_stat->extent_size), | |
644 | lower_page, byte_offset, | |
645 | crypt_stat->extent_size, | |
646 | extent_iv); | |
647 | if (rc != crypt_stat->extent_size) { | |
648 | ecryptfs_printk(KERN_ERR, "Error attempting to " | |
649 | "decrypt extent [0x%.16x]\n", | |
650 | (base_extent + extent_offset)); | |
651 | goto out; | |
652 | } | |
653 | rc = 0; | |
654 | if (unlikely(ecryptfs_verbosity > 0)) { | |
655 | ecryptfs_printk(KERN_DEBUG, "First 8 bytes after " | |
656 | "decryption:\n"); | |
657 | ecryptfs_dump_hex((char *)(page_address(page) | |
658 | + byte_offset), 8); | |
659 | } | |
660 | extent_offset++; | |
661 | } | |
662 | out: | |
663 | if (lower_page_virt) | |
664 | kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt); | |
665 | return rc; | |
666 | } | |
667 | ||
668 | /** | |
669 | * decrypt_scatterlist | |
670 | * | |
671 | * Returns the number of bytes decrypted; negative value on error | |
672 | */ | |
673 | static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, | |
674 | struct scatterlist *dest_sg, | |
675 | struct scatterlist *src_sg, int size, | |
676 | unsigned char *iv) | |
677 | { | |
678 | int rc = 0; | |
679 | ||
680 | /* Consider doing this once, when the file is opened */ | |
681 | mutex_lock(&crypt_stat->cs_tfm_mutex); | |
682 | rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key, | |
683 | crypt_stat->key_size); | |
684 | if (rc) { | |
685 | ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n", | |
686 | rc); | |
687 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
688 | rc = -EINVAL; | |
689 | goto out; | |
690 | } | |
691 | ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size); | |
692 | rc = crypto_cipher_decrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, | |
693 | iv); | |
694 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
695 | if (rc) { | |
696 | ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n", | |
697 | rc); | |
698 | goto out; | |
699 | } | |
700 | rc = size; | |
701 | out: | |
702 | return rc; | |
703 | } | |
704 | ||
705 | /** | |
706 | * ecryptfs_encrypt_page_offset | |
707 | * | |
708 | * Returns the number of bytes encrypted | |
709 | */ | |
710 | static int | |
711 | ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, | |
712 | struct page *dst_page, int dst_offset, | |
713 | struct page *src_page, int src_offset, int size, | |
714 | unsigned char *iv) | |
715 | { | |
716 | struct scatterlist src_sg, dst_sg; | |
717 | ||
718 | src_sg.page = src_page; | |
719 | src_sg.offset = src_offset; | |
720 | src_sg.length = size; | |
721 | dst_sg.page = dst_page; | |
722 | dst_sg.offset = dst_offset; | |
723 | dst_sg.length = size; | |
724 | return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv); | |
725 | } | |
726 | ||
727 | /** | |
728 | * ecryptfs_decrypt_page_offset | |
729 | * | |
730 | * Returns the number of bytes decrypted | |
731 | */ | |
732 | static int | |
733 | ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, | |
734 | struct page *dst_page, int dst_offset, | |
735 | struct page *src_page, int src_offset, int size, | |
736 | unsigned char *iv) | |
737 | { | |
738 | struct scatterlist src_sg, dst_sg; | |
739 | ||
740 | src_sg.page = src_page; | |
741 | src_sg.offset = src_offset; | |
742 | src_sg.length = size; | |
743 | dst_sg.page = dst_page; | |
744 | dst_sg.offset = dst_offset; | |
745 | dst_sg.length = size; | |
746 | return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv); | |
747 | } | |
748 | ||
749 | #define ECRYPTFS_MAX_SCATTERLIST_LEN 4 | |
750 | ||
751 | /** | |
752 | * ecryptfs_init_crypt_ctx | |
753 | * @crypt_stat: Uninitilized crypt stats structure | |
754 | * | |
755 | * Initialize the crypto context. | |
756 | * | |
757 | * TODO: Performance: Keep a cache of initialized cipher contexts; | |
758 | * only init if needed | |
759 | */ | |
760 | int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat) | |
761 | { | |
762 | int rc = -EINVAL; | |
763 | ||
764 | if (!crypt_stat->cipher) { | |
765 | ecryptfs_printk(KERN_ERR, "No cipher specified\n"); | |
766 | goto out; | |
767 | } | |
768 | ecryptfs_printk(KERN_DEBUG, | |
769 | "Initializing cipher [%s]; strlen = [%d]; " | |
770 | "key_size_bits = [%d]\n", | |
771 | crypt_stat->cipher, (int)strlen(crypt_stat->cipher), | |
772 | crypt_stat->key_size << 3); | |
773 | if (crypt_stat->tfm) { | |
774 | rc = 0; | |
775 | goto out; | |
776 | } | |
777 | mutex_lock(&crypt_stat->cs_tfm_mutex); | |
778 | crypt_stat->tfm = crypto_alloc_tfm(crypt_stat->cipher, | |
779 | ECRYPTFS_DEFAULT_CHAINING_MODE | |
780 | | CRYPTO_TFM_REQ_WEAK_KEY); | |
781 | mutex_unlock(&crypt_stat->cs_tfm_mutex); | |
782 | if (!crypt_stat->tfm) { | |
783 | ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): " | |
784 | "Error initializing cipher [%s]\n", | |
785 | crypt_stat->cipher); | |
786 | goto out; | |
787 | } | |
788 | rc = 0; | |
789 | out: | |
790 | return rc; | |
791 | } | |
792 | ||
793 | static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat) | |
794 | { | |
795 | int extent_size_tmp; | |
796 | ||
797 | crypt_stat->extent_mask = 0xFFFFFFFF; | |
798 | crypt_stat->extent_shift = 0; | |
799 | if (crypt_stat->extent_size == 0) | |
800 | return; | |
801 | extent_size_tmp = crypt_stat->extent_size; | |
802 | while ((extent_size_tmp & 0x01) == 0) { | |
803 | extent_size_tmp >>= 1; | |
804 | crypt_stat->extent_mask <<= 1; | |
805 | crypt_stat->extent_shift++; | |
806 | } | |
807 | } | |
808 | ||
809 | void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat) | |
810 | { | |
811 | /* Default values; may be overwritten as we are parsing the | |
812 | * packets. */ | |
813 | crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE; | |
814 | set_extent_mask_and_shift(crypt_stat); | |
815 | crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES; | |
816 | if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) { | |
817 | crypt_stat->header_extent_size = | |
818 | ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE; | |
819 | } else | |
820 | crypt_stat->header_extent_size = PAGE_CACHE_SIZE; | |
821 | crypt_stat->num_header_extents_at_front = 1; | |
822 | } | |
823 | ||
824 | /** | |
825 | * ecryptfs_compute_root_iv | |
826 | * @crypt_stats | |
827 | * | |
828 | * On error, sets the root IV to all 0's. | |
829 | */ | |
830 | int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat) | |
831 | { | |
832 | int rc = 0; | |
833 | char dst[MD5_DIGEST_SIZE]; | |
834 | ||
835 | BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE); | |
836 | BUG_ON(crypt_stat->iv_bytes <= 0); | |
837 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) { | |
838 | rc = -EINVAL; | |
839 | ecryptfs_printk(KERN_WARNING, "Session key not valid; " | |
840 | "cannot generate root IV\n"); | |
841 | goto out; | |
842 | } | |
843 | rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key, | |
844 | crypt_stat->key_size); | |
845 | if (rc) { | |
846 | ecryptfs_printk(KERN_WARNING, "Error attempting to compute " | |
847 | "MD5 while generating root IV\n"); | |
848 | goto out; | |
849 | } | |
850 | memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes); | |
851 | out: | |
852 | if (rc) { | |
853 | memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes); | |
854 | ECRYPTFS_SET_FLAG(crypt_stat->flags, | |
855 | ECRYPTFS_SECURITY_WARNING); | |
856 | } | |
857 | return rc; | |
858 | } | |
859 | ||
860 | static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat) | |
861 | { | |
862 | get_random_bytes(crypt_stat->key, crypt_stat->key_size); | |
863 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); | |
864 | ecryptfs_compute_root_iv(crypt_stat); | |
865 | if (unlikely(ecryptfs_verbosity > 0)) { | |
866 | ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n"); | |
867 | ecryptfs_dump_hex(crypt_stat->key, | |
868 | crypt_stat->key_size); | |
869 | } | |
870 | } | |
871 | ||
872 | /** | |
873 | * ecryptfs_set_default_crypt_stat_vals | |
874 | * @crypt_stat | |
875 | * | |
876 | * Default values in the event that policy does not override them. | |
877 | */ | |
878 | static void ecryptfs_set_default_crypt_stat_vals( | |
879 | struct ecryptfs_crypt_stat *crypt_stat, | |
880 | struct ecryptfs_mount_crypt_stat *mount_crypt_stat) | |
881 | { | |
882 | ecryptfs_set_default_sizes(crypt_stat); | |
883 | strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER); | |
884 | crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES; | |
885 | ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); | |
886 | crypt_stat->file_version = ECRYPTFS_FILE_VERSION; | |
887 | crypt_stat->mount_crypt_stat = mount_crypt_stat; | |
888 | } | |
889 | ||
890 | /** | |
891 | * ecryptfs_new_file_context | |
892 | * @ecryptfs_dentry | |
893 | * | |
894 | * If the crypto context for the file has not yet been established, | |
895 | * this is where we do that. Establishing a new crypto context | |
896 | * involves the following decisions: | |
897 | * - What cipher to use? | |
898 | * - What set of authentication tokens to use? | |
899 | * Here we just worry about getting enough information into the | |
900 | * authentication tokens so that we know that they are available. | |
901 | * We associate the available authentication tokens with the new file | |
902 | * via the set of signatures in the crypt_stat struct. Later, when | |
903 | * the headers are actually written out, we may again defer to | |
904 | * userspace to perform the encryption of the session key; for the | |
905 | * foreseeable future, this will be the case with public key packets. | |
906 | * | |
907 | * Returns zero on success; non-zero otherwise | |
908 | */ | |
909 | /* Associate an authentication token(s) with the file */ | |
910 | int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry) | |
911 | { | |
912 | int rc = 0; | |
913 | struct ecryptfs_crypt_stat *crypt_stat = | |
914 | &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat; | |
915 | struct ecryptfs_mount_crypt_stat *mount_crypt_stat = | |
916 | &ecryptfs_superblock_to_private( | |
917 | ecryptfs_dentry->d_sb)->mount_crypt_stat; | |
918 | int cipher_name_len; | |
919 | ||
920 | ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat); | |
921 | /* See if there are mount crypt options */ | |
922 | if (mount_crypt_stat->global_auth_tok) { | |
923 | ecryptfs_printk(KERN_DEBUG, "Initializing context for new " | |
924 | "file using mount_crypt_stat\n"); | |
925 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED); | |
926 | ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); | |
927 | memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++], | |
928 | mount_crypt_stat->global_auth_tok_sig, | |
929 | ECRYPTFS_SIG_SIZE_HEX); | |
930 | cipher_name_len = | |
931 | strlen(mount_crypt_stat->global_default_cipher_name); | |
932 | memcpy(crypt_stat->cipher, | |
933 | mount_crypt_stat->global_default_cipher_name, | |
934 | cipher_name_len); | |
935 | crypt_stat->cipher[cipher_name_len] = '\0'; | |
936 | crypt_stat->key_size = | |
937 | mount_crypt_stat->global_default_cipher_key_size; | |
938 | ecryptfs_generate_new_key(crypt_stat); | |
939 | } else | |
940 | /* We should not encounter this scenario since we | |
941 | * should detect lack of global_auth_tok at mount time | |
942 | * TODO: Applies to 0.1 release only; remove in future | |
943 | * release */ | |
944 | BUG(); | |
945 | rc = ecryptfs_init_crypt_ctx(crypt_stat); | |
946 | if (rc) | |
947 | ecryptfs_printk(KERN_ERR, "Error initializing cryptographic " | |
948 | "context for cipher [%s]: rc = [%d]\n", | |
949 | crypt_stat->cipher, rc); | |
950 | return rc; | |
951 | } | |
952 | ||
953 | /** | |
954 | * contains_ecryptfs_marker - check for the ecryptfs marker | |
955 | * @data: The data block in which to check | |
956 | * | |
957 | * Returns one if marker found; zero if not found | |
958 | */ | |
959 | int contains_ecryptfs_marker(char *data) | |
960 | { | |
961 | u32 m_1, m_2; | |
962 | ||
963 | memcpy(&m_1, data, 4); | |
964 | m_1 = be32_to_cpu(m_1); | |
965 | memcpy(&m_2, (data + 4), 4); | |
966 | m_2 = be32_to_cpu(m_2); | |
967 | if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2) | |
968 | return 1; | |
969 | ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; " | |
970 | "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2, | |
971 | MAGIC_ECRYPTFS_MARKER); | |
972 | ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = " | |
973 | "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER)); | |
974 | return 0; | |
975 | } | |
976 | ||
977 | struct ecryptfs_flag_map_elem { | |
978 | u32 file_flag; | |
979 | u32 local_flag; | |
980 | }; | |
981 | ||
982 | /* Add support for additional flags by adding elements here. */ | |
983 | static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = { | |
984 | {0x00000001, ECRYPTFS_ENABLE_HMAC}, | |
985 | {0x00000002, ECRYPTFS_ENCRYPTED} | |
986 | }; | |
987 | ||
988 | /** | |
989 | * ecryptfs_process_flags | |
990 | * @crypt_stat | |
991 | * @page_virt: Source data to be parsed | |
992 | * @bytes_read: Updated with the number of bytes read | |
993 | * | |
994 | * Returns zero on success; non-zero if the flag set is invalid | |
995 | */ | |
996 | static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat, | |
997 | char *page_virt, int *bytes_read) | |
998 | { | |
999 | int rc = 0; | |
1000 | int i; | |
1001 | u32 flags; | |
1002 | ||
1003 | memcpy(&flags, page_virt, 4); | |
1004 | flags = be32_to_cpu(flags); | |
1005 | for (i = 0; i < ((sizeof(ecryptfs_flag_map) | |
1006 | / sizeof(struct ecryptfs_flag_map_elem))); i++) | |
1007 | if (flags & ecryptfs_flag_map[i].file_flag) { | |
1008 | ECRYPTFS_SET_FLAG(crypt_stat->flags, | |
1009 | ecryptfs_flag_map[i].local_flag); | |
1010 | } else | |
1011 | ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, | |
1012 | ecryptfs_flag_map[i].local_flag); | |
1013 | /* Version is in top 8 bits of the 32-bit flag vector */ | |
1014 | crypt_stat->file_version = ((flags >> 24) & 0xFF); | |
1015 | (*bytes_read) = 4; | |
1016 | return rc; | |
1017 | } | |
1018 | ||
1019 | /** | |
1020 | * write_ecryptfs_marker | |
1021 | * @page_virt: The pointer to in a page to begin writing the marker | |
1022 | * @written: Number of bytes written | |
1023 | * | |
1024 | * Marker = 0x3c81b7f5 | |
1025 | */ | |
1026 | static void write_ecryptfs_marker(char *page_virt, size_t *written) | |
1027 | { | |
1028 | u32 m_1, m_2; | |
1029 | ||
1030 | get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); | |
1031 | m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER); | |
1032 | m_1 = cpu_to_be32(m_1); | |
1033 | memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); | |
1034 | m_2 = cpu_to_be32(m_2); | |
1035 | memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2, | |
1036 | (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); | |
1037 | (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; | |
1038 | } | |
1039 | ||
1040 | static void | |
1041 | write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat, | |
1042 | size_t *written) | |
1043 | { | |
1044 | u32 flags = 0; | |
1045 | int i; | |
1046 | ||
1047 | for (i = 0; i < ((sizeof(ecryptfs_flag_map) | |
1048 | / sizeof(struct ecryptfs_flag_map_elem))); i++) | |
1049 | if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
1050 | ecryptfs_flag_map[i].local_flag)) | |
1051 | flags |= ecryptfs_flag_map[i].file_flag; | |
1052 | /* Version is in top 8 bits of the 32-bit flag vector */ | |
1053 | flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000); | |
1054 | flags = cpu_to_be32(flags); | |
1055 | memcpy(page_virt, &flags, 4); | |
1056 | (*written) = 4; | |
1057 | } | |
1058 | ||
1059 | struct ecryptfs_cipher_code_str_map_elem { | |
1060 | char cipher_str[16]; | |
1061 | u16 cipher_code; | |
1062 | }; | |
1063 | ||
1064 | /* Add support for additional ciphers by adding elements here. The | |
1065 | * cipher_code is whatever OpenPGP applicatoins use to identify the | |
1066 | * ciphers. List in order of probability. */ | |
1067 | static struct ecryptfs_cipher_code_str_map_elem | |
1068 | ecryptfs_cipher_code_str_map[] = { | |
1069 | {"aes",RFC2440_CIPHER_AES_128 }, | |
1070 | {"blowfish", RFC2440_CIPHER_BLOWFISH}, | |
1071 | {"des3_ede", RFC2440_CIPHER_DES3_EDE}, | |
1072 | {"cast5", RFC2440_CIPHER_CAST_5}, | |
1073 | {"twofish", RFC2440_CIPHER_TWOFISH}, | |
1074 | {"cast6", RFC2440_CIPHER_CAST_6}, | |
1075 | {"aes", RFC2440_CIPHER_AES_192}, | |
1076 | {"aes", RFC2440_CIPHER_AES_256} | |
1077 | }; | |
1078 | ||
1079 | /** | |
1080 | * ecryptfs_code_for_cipher_string | |
1081 | * @str: The string representing the cipher name | |
1082 | * | |
1083 | * Returns zero on no match, or the cipher code on match | |
1084 | */ | |
1085 | u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat) | |
1086 | { | |
1087 | int i; | |
1088 | u16 code = 0; | |
1089 | struct ecryptfs_cipher_code_str_map_elem *map = | |
1090 | ecryptfs_cipher_code_str_map; | |
1091 | ||
1092 | if (strcmp(crypt_stat->cipher, "aes") == 0) { | |
1093 | switch (crypt_stat->key_size) { | |
1094 | case 16: | |
1095 | code = RFC2440_CIPHER_AES_128; | |
1096 | break; | |
1097 | case 24: | |
1098 | code = RFC2440_CIPHER_AES_192; | |
1099 | break; | |
1100 | case 32: | |
1101 | code = RFC2440_CIPHER_AES_256; | |
1102 | } | |
1103 | } else { | |
1104 | for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) | |
1105 | if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){ | |
1106 | code = map[i].cipher_code; | |
1107 | break; | |
1108 | } | |
1109 | } | |
1110 | return code; | |
1111 | } | |
1112 | ||
1113 | /** | |
1114 | * ecryptfs_cipher_code_to_string | |
1115 | * @str: Destination to write out the cipher name | |
1116 | * @cipher_code: The code to convert to cipher name string | |
1117 | * | |
1118 | * Returns zero on success | |
1119 | */ | |
1120 | int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code) | |
1121 | { | |
1122 | int rc = 0; | |
1123 | int i; | |
1124 | ||
1125 | str[0] = '\0'; | |
1126 | for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) | |
1127 | if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code) | |
1128 | strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str); | |
1129 | if (str[0] == '\0') { | |
1130 | ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: " | |
1131 | "[%d]\n", cipher_code); | |
1132 | rc = -EINVAL; | |
1133 | } | |
1134 | return rc; | |
1135 | } | |
1136 | ||
1137 | /** | |
1138 | * ecryptfs_read_header_region | |
1139 | * @data | |
1140 | * @dentry | |
1141 | * @nd | |
1142 | * | |
1143 | * Returns zero on success; non-zero otherwise | |
1144 | */ | |
1145 | int ecryptfs_read_header_region(char *data, struct dentry *dentry, | |
1146 | struct vfsmount *mnt) | |
1147 | { | |
1148 | struct file *file; | |
1149 | mm_segment_t oldfs; | |
1150 | int rc; | |
1151 | ||
1152 | mnt = mntget(mnt); | |
1153 | file = dentry_open(dentry, mnt, O_RDONLY); | |
1154 | if (IS_ERR(file)) { | |
1155 | ecryptfs_printk(KERN_DEBUG, "Error opening file to " | |
1156 | "read header region\n"); | |
1157 | mntput(mnt); | |
1158 | rc = PTR_ERR(file); | |
1159 | goto out; | |
1160 | } | |
1161 | file->f_pos = 0; | |
1162 | oldfs = get_fs(); | |
1163 | set_fs(get_ds()); | |
1164 | /* For releases 0.1 and 0.2, all of the header information | |
1165 | * fits in the first data extent-sized region. */ | |
1166 | rc = file->f_op->read(file, (char __user *)data, | |
1167 | ECRYPTFS_DEFAULT_EXTENT_SIZE, &file->f_pos); | |
1168 | set_fs(oldfs); | |
1169 | fput(file); | |
1170 | rc = 0; | |
1171 | out: | |
1172 | return rc; | |
1173 | } | |
1174 | ||
1175 | static void | |
1176 | write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat, | |
1177 | size_t *written) | |
1178 | { | |
1179 | u32 header_extent_size; | |
1180 | u16 num_header_extents_at_front; | |
1181 | ||
1182 | header_extent_size = (u32)crypt_stat->header_extent_size; | |
1183 | num_header_extents_at_front = | |
1184 | (u16)crypt_stat->num_header_extents_at_front; | |
1185 | header_extent_size = cpu_to_be32(header_extent_size); | |
1186 | memcpy(virt, &header_extent_size, 4); | |
1187 | virt += 4; | |
1188 | num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front); | |
1189 | memcpy(virt, &num_header_extents_at_front, 2); | |
1190 | (*written) = 6; | |
1191 | } | |
1192 | ||
1193 | struct kmem_cache *ecryptfs_header_cache_0; | |
1194 | struct kmem_cache *ecryptfs_header_cache_1; | |
1195 | struct kmem_cache *ecryptfs_header_cache_2; | |
1196 | ||
1197 | /** | |
1198 | * ecryptfs_write_headers_virt | |
1199 | * @page_virt | |
1200 | * @crypt_stat | |
1201 | * @ecryptfs_dentry | |
1202 | * | |
1203 | * Format version: 1 | |
1204 | * | |
1205 | * Header Extent: | |
1206 | * Octets 0-7: Unencrypted file size (big-endian) | |
1207 | * Octets 8-15: eCryptfs special marker | |
1208 | * Octets 16-19: Flags | |
1209 | * Octet 16: File format version number (between 0 and 255) | |
1210 | * Octets 17-18: Reserved | |
1211 | * Octet 19: Bit 1 (lsb): Reserved | |
1212 | * Bit 2: Encrypted? | |
1213 | * Bits 3-8: Reserved | |
1214 | * Octets 20-23: Header extent size (big-endian) | |
1215 | * Octets 24-25: Number of header extents at front of file | |
1216 | * (big-endian) | |
1217 | * Octet 26: Begin RFC 2440 authentication token packet set | |
1218 | * Data Extent 0: | |
1219 | * Lower data (CBC encrypted) | |
1220 | * Data Extent 1: | |
1221 | * Lower data (CBC encrypted) | |
1222 | * ... | |
1223 | * | |
1224 | * Returns zero on success | |
1225 | */ | |
1226 | int ecryptfs_write_headers_virt(char *page_virt, | |
1227 | struct ecryptfs_crypt_stat *crypt_stat, | |
1228 | struct dentry *ecryptfs_dentry) | |
1229 | { | |
1230 | int rc; | |
1231 | size_t written; | |
1232 | size_t offset; | |
1233 | ||
1234 | offset = ECRYPTFS_FILE_SIZE_BYTES; | |
1235 | write_ecryptfs_marker((page_virt + offset), &written); | |
1236 | offset += written; | |
1237 | write_ecryptfs_flags((page_virt + offset), crypt_stat, &written); | |
1238 | offset += written; | |
1239 | write_header_metadata((page_virt + offset), crypt_stat, &written); | |
1240 | offset += written; | |
1241 | rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat, | |
1242 | ecryptfs_dentry, &written, | |
1243 | PAGE_CACHE_SIZE - offset); | |
1244 | if (rc) | |
1245 | ecryptfs_printk(KERN_WARNING, "Error generating key packet " | |
1246 | "set; rc = [%d]\n", rc); | |
1247 | return rc; | |
1248 | } | |
1249 | ||
1250 | /** | |
1251 | * ecryptfs_write_headers | |
1252 | * @lower_file: The lower file struct, which was returned from dentry_open | |
1253 | * | |
1254 | * Write the file headers out. This will likely involve a userspace | |
1255 | * callout, in which the session key is encrypted with one or more | |
1256 | * public keys and/or the passphrase necessary to do the encryption is | |
1257 | * retrieved via a prompt. Exactly what happens at this point should | |
1258 | * be policy-dependent. | |
1259 | * | |
1260 | * Returns zero on success; non-zero on error | |
1261 | */ | |
1262 | int ecryptfs_write_headers(struct dentry *ecryptfs_dentry, | |
1263 | struct file *lower_file) | |
1264 | { | |
1265 | mm_segment_t oldfs; | |
1266 | struct ecryptfs_crypt_stat *crypt_stat; | |
1267 | char *page_virt; | |
1268 | int current_header_page; | |
1269 | int header_pages; | |
1270 | int rc = 0; | |
1271 | ||
1272 | crypt_stat = &ecryptfs_inode_to_private( | |
1273 | ecryptfs_dentry->d_inode)->crypt_stat; | |
1274 | if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
1275 | ECRYPTFS_ENCRYPTED))) { | |
1276 | if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, | |
1277 | ECRYPTFS_KEY_VALID)) { | |
1278 | ecryptfs_printk(KERN_DEBUG, "Key is " | |
1279 | "invalid; bailing out\n"); | |
1280 | rc = -EINVAL; | |
1281 | goto out; | |
1282 | } | |
1283 | } else { | |
1284 | rc = -EINVAL; | |
1285 | ecryptfs_printk(KERN_WARNING, | |
1286 | "Called with crypt_stat->encrypted == 0\n"); | |
1287 | goto out; | |
1288 | } | |
1289 | /* Released in this function */ | |
1290 | page_virt = kmem_cache_alloc(ecryptfs_header_cache_0, SLAB_USER); | |
1291 | if (!page_virt) { | |
1292 | ecryptfs_printk(KERN_ERR, "Out of memory\n"); | |
1293 | rc = -ENOMEM; | |
1294 | goto out; | |
1295 | } | |
1296 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1297 | rc = ecryptfs_write_headers_virt(page_virt, crypt_stat, | |
1298 | ecryptfs_dentry); | |
1299 | if (unlikely(rc)) { | |
1300 | ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n"); | |
1301 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1302 | goto out_free; | |
1303 | } | |
1304 | ecryptfs_printk(KERN_DEBUG, | |
1305 | "Writing key packet set to underlying file\n"); | |
1306 | lower_file->f_pos = 0; | |
1307 | oldfs = get_fs(); | |
1308 | set_fs(get_ds()); | |
1309 | ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->" | |
1310 | "write() w/ header page; lower_file->f_pos = " | |
1311 | "[0x%.16x]\n", lower_file->f_pos); | |
1312 | lower_file->f_op->write(lower_file, (char __user *)page_virt, | |
1313 | PAGE_CACHE_SIZE, &lower_file->f_pos); | |
1314 | header_pages = ((crypt_stat->header_extent_size | |
1315 | * crypt_stat->num_header_extents_at_front) | |
1316 | / PAGE_CACHE_SIZE); | |
1317 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1318 | current_header_page = 1; | |
1319 | while (current_header_page < header_pages) { | |
1320 | ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->" | |
1321 | "write() w/ zero'd page; lower_file->f_pos = " | |
1322 | "[0x%.16x]\n", lower_file->f_pos); | |
1323 | lower_file->f_op->write(lower_file, (char __user *)page_virt, | |
1324 | PAGE_CACHE_SIZE, &lower_file->f_pos); | |
1325 | current_header_page++; | |
1326 | } | |
1327 | set_fs(oldfs); | |
1328 | ecryptfs_printk(KERN_DEBUG, | |
1329 | "Done writing key packet set to underlying file.\n"); | |
1330 | out_free: | |
1331 | kmem_cache_free(ecryptfs_header_cache_0, page_virt); | |
1332 | out: | |
1333 | return rc; | |
1334 | } | |
1335 | ||
1336 | static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat, | |
1337 | char *virt, int *bytes_read) | |
1338 | { | |
1339 | int rc = 0; | |
1340 | u32 header_extent_size; | |
1341 | u16 num_header_extents_at_front; | |
1342 | ||
1343 | memcpy(&header_extent_size, virt, 4); | |
1344 | header_extent_size = be32_to_cpu(header_extent_size); | |
1345 | virt += 4; | |
1346 | memcpy(&num_header_extents_at_front, virt, 2); | |
1347 | num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front); | |
1348 | crypt_stat->header_extent_size = (int)header_extent_size; | |
1349 | crypt_stat->num_header_extents_at_front = | |
1350 | (int)num_header_extents_at_front; | |
1351 | (*bytes_read) = 6; | |
1352 | if ((crypt_stat->header_extent_size | |
1353 | * crypt_stat->num_header_extents_at_front) | |
1354 | < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) { | |
1355 | rc = -EINVAL; | |
1356 | ecryptfs_printk(KERN_WARNING, "Invalid header extent size: " | |
1357 | "[%d]\n", crypt_stat->header_extent_size); | |
1358 | } | |
1359 | return rc; | |
1360 | } | |
1361 | ||
1362 | /** | |
1363 | * set_default_header_data | |
1364 | * | |
1365 | * For version 0 file format; this function is only for backwards | |
1366 | * compatibility for files created with the prior versions of | |
1367 | * eCryptfs. | |
1368 | */ | |
1369 | static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat) | |
1370 | { | |
1371 | crypt_stat->header_extent_size = 4096; | |
1372 | crypt_stat->num_header_extents_at_front = 1; | |
1373 | } | |
1374 | ||
1375 | /** | |
1376 | * ecryptfs_read_headers_virt | |
1377 | * | |
1378 | * Read/parse the header data. The header format is detailed in the | |
1379 | * comment block for the ecryptfs_write_headers_virt() function. | |
1380 | * | |
1381 | * Returns zero on success | |
1382 | */ | |
1383 | static int ecryptfs_read_headers_virt(char *page_virt, | |
1384 | struct ecryptfs_crypt_stat *crypt_stat, | |
1385 | struct dentry *ecryptfs_dentry) | |
1386 | { | |
1387 | int rc = 0; | |
1388 | int offset; | |
1389 | int bytes_read; | |
1390 | ||
1391 | ecryptfs_set_default_sizes(crypt_stat); | |
1392 | crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private( | |
1393 | ecryptfs_dentry->d_sb)->mount_crypt_stat; | |
1394 | offset = ECRYPTFS_FILE_SIZE_BYTES; | |
1395 | rc = contains_ecryptfs_marker(page_virt + offset); | |
1396 | if (rc == 0) { | |
1397 | rc = -EINVAL; | |
1398 | goto out; | |
1399 | } | |
1400 | offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; | |
1401 | rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset), | |
1402 | &bytes_read); | |
1403 | if (rc) { | |
1404 | ecryptfs_printk(KERN_WARNING, "Error processing flags\n"); | |
1405 | goto out; | |
1406 | } | |
1407 | if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) { | |
1408 | ecryptfs_printk(KERN_WARNING, "File version is [%d]; only " | |
1409 | "file version [%d] is supported by this " | |
1410 | "version of eCryptfs\n", | |
1411 | crypt_stat->file_version, | |
1412 | ECRYPTFS_SUPPORTED_FILE_VERSION); | |
1413 | rc = -EINVAL; | |
1414 | goto out; | |
1415 | } | |
1416 | offset += bytes_read; | |
1417 | if (crypt_stat->file_version >= 1) { | |
1418 | rc = parse_header_metadata(crypt_stat, (page_virt + offset), | |
1419 | &bytes_read); | |
1420 | if (rc) { | |
1421 | ecryptfs_printk(KERN_WARNING, "Error reading header " | |
1422 | "metadata; rc = [%d]\n", rc); | |
1423 | } | |
1424 | offset += bytes_read; | |
1425 | } else | |
1426 | set_default_header_data(crypt_stat); | |
1427 | rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset), | |
1428 | ecryptfs_dentry); | |
1429 | out: | |
1430 | return rc; | |
1431 | } | |
1432 | ||
1433 | /** | |
1434 | * ecryptfs_read_headers | |
1435 | * | |
1436 | * Returns zero if valid headers found and parsed; non-zero otherwise | |
1437 | */ | |
1438 | int ecryptfs_read_headers(struct dentry *ecryptfs_dentry, | |
1439 | struct file *lower_file) | |
1440 | { | |
1441 | int rc = 0; | |
1442 | char *page_virt = NULL; | |
1443 | mm_segment_t oldfs; | |
1444 | ssize_t bytes_read; | |
1445 | struct ecryptfs_crypt_stat *crypt_stat = | |
1446 | &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat; | |
1447 | ||
1448 | /* Read the first page from the underlying file */ | |
1449 | page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_USER); | |
1450 | if (!page_virt) { | |
1451 | rc = -ENOMEM; | |
1452 | ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n"); | |
1453 | goto out; | |
1454 | } | |
1455 | lower_file->f_pos = 0; | |
1456 | oldfs = get_fs(); | |
1457 | set_fs(get_ds()); | |
1458 | bytes_read = lower_file->f_op->read(lower_file, | |
1459 | (char __user *)page_virt, | |
1460 | ECRYPTFS_DEFAULT_EXTENT_SIZE, | |
1461 | &lower_file->f_pos); | |
1462 | set_fs(oldfs); | |
1463 | if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) { | |
1464 | rc = -EINVAL; | |
1465 | goto out; | |
1466 | } | |
1467 | rc = ecryptfs_read_headers_virt(page_virt, crypt_stat, | |
1468 | ecryptfs_dentry); | |
1469 | if (rc) { | |
1470 | ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not " | |
1471 | "found\n"); | |
1472 | rc = -EINVAL; | |
1473 | } | |
1474 | out: | |
1475 | if (page_virt) { | |
1476 | memset(page_virt, 0, PAGE_CACHE_SIZE); | |
1477 | kmem_cache_free(ecryptfs_header_cache_1, page_virt); | |
1478 | } | |
1479 | return rc; | |
1480 | } | |
1481 | ||
1482 | /** | |
1483 | * ecryptfs_encode_filename - converts a plaintext file name to cipher text | |
1484 | * @crypt_stat: The crypt_stat struct associated with the file anem to encode | |
1485 | * @name: The plaintext name | |
1486 | * @length: The length of the plaintext | |
1487 | * @encoded_name: The encypted name | |
1488 | * | |
1489 | * Encrypts and encodes a filename into something that constitutes a | |
1490 | * valid filename for a filesystem, with printable characters. | |
1491 | * | |
1492 | * We assume that we have a properly initialized crypto context, | |
1493 | * pointed to by crypt_stat->tfm. | |
1494 | * | |
1495 | * TODO: Implement filename decoding and decryption here, in place of | |
1496 | * memcpy. We are keeping the framework around for now to (1) | |
1497 | * facilitate testing of the components needed to implement filename | |
1498 | * encryption and (2) to provide a code base from which other | |
1499 | * developers in the community can easily implement this feature. | |
1500 | * | |
1501 | * Returns the length of encoded filename; negative if error | |
1502 | */ | |
1503 | int | |
1504 | ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat, | |
1505 | const char *name, int length, char **encoded_name) | |
1506 | { | |
1507 | int error = 0; | |
1508 | ||
1509 | (*encoded_name) = kmalloc(length + 2, GFP_KERNEL); | |
1510 | if (!(*encoded_name)) { | |
1511 | error = -ENOMEM; | |
1512 | goto out; | |
1513 | } | |
1514 | /* TODO: Filename encryption is a scheduled feature for a | |
1515 | * future version of eCryptfs. This function is here only for | |
1516 | * the purpose of providing a framework for other developers | |
1517 | * to easily implement filename encryption. Hint: Replace this | |
1518 | * memcpy() with a call to encrypt and encode the | |
1519 | * filename, the set the length accordingly. */ | |
1520 | memcpy((void *)(*encoded_name), (void *)name, length); | |
1521 | (*encoded_name)[length] = '\0'; | |
1522 | error = length + 1; | |
1523 | out: | |
1524 | return error; | |
1525 | } | |
1526 | ||
1527 | /** | |
1528 | * ecryptfs_decode_filename - converts the cipher text name to plaintext | |
1529 | * @crypt_stat: The crypt_stat struct associated with the file | |
1530 | * @name: The filename in cipher text | |
1531 | * @length: The length of the cipher text name | |
1532 | * @decrypted_name: The plaintext name | |
1533 | * | |
1534 | * Decodes and decrypts the filename. | |
1535 | * | |
1536 | * We assume that we have a properly initialized crypto context, | |
1537 | * pointed to by crypt_stat->tfm. | |
1538 | * | |
1539 | * TODO: Implement filename decoding and decryption here, in place of | |
1540 | * memcpy. We are keeping the framework around for now to (1) | |
1541 | * facilitate testing of the components needed to implement filename | |
1542 | * encryption and (2) to provide a code base from which other | |
1543 | * developers in the community can easily implement this feature. | |
1544 | * | |
1545 | * Returns the length of decoded filename; negative if error | |
1546 | */ | |
1547 | int | |
1548 | ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat, | |
1549 | const char *name, int length, char **decrypted_name) | |
1550 | { | |
1551 | int error = 0; | |
1552 | ||
1553 | (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL); | |
1554 | if (!(*decrypted_name)) { | |
1555 | error = -ENOMEM; | |
1556 | goto out; | |
1557 | } | |
1558 | /* TODO: Filename encryption is a scheduled feature for a | |
1559 | * future version of eCryptfs. This function is here only for | |
1560 | * the purpose of providing a framework for other developers | |
1561 | * to easily implement filename encryption. Hint: Replace this | |
1562 | * memcpy() with a call to decode and decrypt the | |
1563 | * filename, the set the length accordingly. */ | |
1564 | memcpy((void *)(*decrypted_name), (void *)name, length); | |
1565 | (*decrypted_name)[length + 1] = '\0'; /* Only for convenience | |
1566 | * in printing out the | |
1567 | * string in debug | |
1568 | * messages */ | |
1569 | error = length; | |
1570 | out: | |
1571 | return error; | |
1572 | } | |
1573 | ||
1574 | /** | |
1575 | * ecryptfs_process_cipher - Perform cipher initialization. | |
1576 | * @tfm: Crypto context set by this function | |
1577 | * @key_tfm: Crypto context for key material, set by this function | |
1578 | * @cipher_name: Name of the cipher. | |
1579 | * @key_size: Size of the key in bytes. | |
1580 | * | |
1581 | * Returns zero on success. Any crypto_tfm structs allocated here | |
1582 | * should be released by other functions, such as on a superblock put | |
1583 | * event, regardless of whether this function succeeds for fails. | |
1584 | */ | |
1585 | int | |
1586 | ecryptfs_process_cipher(struct crypto_tfm **tfm, struct crypto_tfm **key_tfm, | |
1587 | char *cipher_name, size_t key_size) | |
1588 | { | |
1589 | char dummy_key[ECRYPTFS_MAX_KEY_BYTES]; | |
1590 | int rc; | |
1591 | ||
1592 | *tfm = *key_tfm = NULL; | |
1593 | if (key_size > ECRYPTFS_MAX_KEY_BYTES) { | |
1594 | rc = -EINVAL; | |
1595 | printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum " | |
1596 | "allowable is [%d]\n", key_size, ECRYPTFS_MAX_KEY_BYTES); | |
1597 | goto out; | |
1598 | } | |
1599 | *tfm = crypto_alloc_tfm(cipher_name, (ECRYPTFS_DEFAULT_CHAINING_MODE | |
1600 | | CRYPTO_TFM_REQ_WEAK_KEY)); | |
1601 | if (!(*tfm)) { | |
1602 | rc = -EINVAL; | |
1603 | printk(KERN_ERR "Unable to allocate crypto cipher with name " | |
1604 | "[%s]\n", cipher_name); | |
1605 | goto out; | |
1606 | } | |
1607 | *key_tfm = crypto_alloc_tfm(cipher_name, CRYPTO_TFM_REQ_WEAK_KEY); | |
1608 | if (!(*key_tfm)) { | |
1609 | rc = -EINVAL; | |
1610 | printk(KERN_ERR "Unable to allocate crypto cipher with name " | |
1611 | "[%s]\n", cipher_name); | |
1612 | goto out; | |
1613 | } | |
1614 | if (key_size < crypto_tfm_alg_min_keysize(*tfm)) { | |
1615 | rc = -EINVAL; | |
1616 | printk(KERN_ERR "Request key size is [%Zd]; minimum key size " | |
1617 | "supported by cipher [%s] is [%d]\n", key_size, | |
1618 | cipher_name, crypto_tfm_alg_min_keysize(*tfm)); | |
1619 | goto out; | |
1620 | } | |
1621 | if (key_size < crypto_tfm_alg_min_keysize(*key_tfm)) { | |
1622 | rc = -EINVAL; | |
1623 | printk(KERN_ERR "Request key size is [%Zd]; minimum key size " | |
1624 | "supported by cipher [%s] is [%d]\n", key_size, | |
1625 | cipher_name, crypto_tfm_alg_min_keysize(*key_tfm)); | |
1626 | goto out; | |
1627 | } | |
1628 | if (key_size > crypto_tfm_alg_max_keysize(*tfm)) { | |
1629 | rc = -EINVAL; | |
1630 | printk(KERN_ERR "Request key size is [%Zd]; maximum key size " | |
1631 | "supported by cipher [%s] is [%d]\n", key_size, | |
1632 | cipher_name, crypto_tfm_alg_min_keysize(*tfm)); | |
1633 | goto out; | |
1634 | } | |
1635 | if (key_size > crypto_tfm_alg_max_keysize(*key_tfm)) { | |
1636 | rc = -EINVAL; | |
1637 | printk(KERN_ERR "Request key size is [%Zd]; maximum key size " | |
1638 | "supported by cipher [%s] is [%d]\n", key_size, | |
1639 | cipher_name, crypto_tfm_alg_min_keysize(*key_tfm)); | |
1640 | goto out; | |
1641 | } | |
1642 | get_random_bytes(dummy_key, key_size); | |
1643 | rc = crypto_cipher_setkey(*tfm, dummy_key, key_size); | |
1644 | if (rc) { | |
1645 | printk(KERN_ERR "Error attempting to set key of size [%Zd] for " | |
1646 | "cipher [%s]; rc = [%d]\n", key_size, cipher_name, rc); | |
1647 | rc = -EINVAL; | |
1648 | goto out; | |
1649 | } | |
1650 | rc = crypto_cipher_setkey(*key_tfm, dummy_key, key_size); | |
1651 | if (rc) { | |
1652 | printk(KERN_ERR "Error attempting to set key of size [%Zd] for " | |
1653 | "cipher [%s]; rc = [%d]\n", key_size, cipher_name, rc); | |
1654 | rc = -EINVAL; | |
1655 | goto out; | |
1656 | } | |
1657 | out: | |
1658 | return rc; | |
1659 | } |