eCryptfs: grammatical fix (destruct to destroy)
[linux-2.6.git] / fs / ecryptfs / crypto.c
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) 2004-2007 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         struct scatterlist sg;
98         struct hash_desc desc = {
99                 .tfm = crypt_stat->hash_tfm,
100                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
101         };
102         int rc = 0;
103
104         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
105         sg_init_one(&sg, (u8 *)src, len);
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);
111                         ecryptfs_printk(KERN_ERR, "Error attempting to "
112                                         "allocate crypto context; rc = [%d]\n",
113                                         rc);
114                         goto out;
115                 }
116                 crypt_stat->hash_tfm = desc.tfm;
117         }
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);
122 out:
123         return rc;
124 }
125
126 int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
127                                            char *cipher_name,
128                                            char *chaining_modifier)
129 {
130         int cipher_name_len = strlen(cipher_name);
131         int chaining_modifier_len = strlen(chaining_modifier);
132         int algified_name_len;
133         int rc;
134
135         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
136         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
137         if (!(*algified_name)) {
138                 rc = -ENOMEM;
139                 goto out;
140         }
141         snprintf((*algified_name), algified_name_len, "%s(%s)",
142                  chaining_modifier, cipher_name);
143         rc = 0;
144 out:
145         return rc;
146 }
147
148 /**
149  * ecryptfs_derive_iv
150  * @iv: destination for the derived iv vale
151  * @crypt_stat: Pointer to crypt_stat struct for the current inode
152  * @offset: Offset of the page whose's iv we are to derive
153  *
154  * Generate the initialization vector from the given root IV and page
155  * offset.
156  *
157  * Returns zero on success; non-zero on error.
158  */
159 static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
160                               pgoff_t offset)
161 {
162         int rc = 0;
163         char dst[MD5_DIGEST_SIZE];
164         char src[ECRYPTFS_MAX_IV_BYTES + 16];
165
166         if (unlikely(ecryptfs_verbosity > 0)) {
167                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
168                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
169         }
170         /* TODO: It is probably secure to just cast the least
171          * significant bits of the root IV into an unsigned long and
172          * add the offset to that rather than go through all this
173          * hashing business. -Halcrow */
174         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
175         memset((src + crypt_stat->iv_bytes), 0, 16);
176         snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset);
177         if (unlikely(ecryptfs_verbosity > 0)) {
178                 ecryptfs_printk(KERN_DEBUG, "source:\n");
179                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
180         }
181         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
182                                     (crypt_stat->iv_bytes + 16));
183         if (rc) {
184                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
185                                 "MD5 while generating IV for a page\n");
186                 goto out;
187         }
188         memcpy(iv, dst, crypt_stat->iv_bytes);
189         if (unlikely(ecryptfs_verbosity > 0)) {
190                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
191                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
192         }
193 out:
194         return rc;
195 }
196
197 /**
198  * ecryptfs_init_crypt_stat
199  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
200  *
201  * Initialize the crypt_stat structure.
202  */
203 void
204 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
205 {
206         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
207         INIT_LIST_HEAD(&crypt_stat->keysig_list);
208         mutex_init(&crypt_stat->keysig_list_mutex);
209         mutex_init(&crypt_stat->cs_mutex);
210         mutex_init(&crypt_stat->cs_tfm_mutex);
211         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
212         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
213 }
214
215 /**
216  * ecryptfs_destroy_crypt_stat
217  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
218  *
219  * Releases all memory associated with a crypt_stat struct.
220  */
221 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
222 {
223         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
224
225         if (crypt_stat->tfm)
226                 crypto_free_blkcipher(crypt_stat->tfm);
227         if (crypt_stat->hash_tfm)
228                 crypto_free_hash(crypt_stat->hash_tfm);
229         mutex_lock(&crypt_stat->keysig_list_mutex);
230         list_for_each_entry_safe(key_sig, key_sig_tmp,
231                                  &crypt_stat->keysig_list, crypt_stat_list) {
232                 list_del(&key_sig->crypt_stat_list);
233                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
234         }
235         mutex_unlock(&crypt_stat->keysig_list_mutex);
236         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
237 }
238
239 void ecryptfs_destroy_mount_crypt_stat(
240         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
241 {
242         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
243
244         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
245                 return;
246         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
247         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
248                                  &mount_crypt_stat->global_auth_tok_list,
249                                  mount_crypt_stat_list) {
250                 list_del(&auth_tok->mount_crypt_stat_list);
251                 mount_crypt_stat->num_global_auth_toks--;
252                 if (auth_tok->global_auth_tok_key
253                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
254                         key_put(auth_tok->global_auth_tok_key);
255                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
256         }
257         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
258         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
259 }
260
261 /**
262  * virt_to_scatterlist
263  * @addr: Virtual address
264  * @size: Size of data; should be an even multiple of the block size
265  * @sg: Pointer to scatterlist array; set to NULL to obtain only
266  *      the number of scatterlist structs required in array
267  * @sg_size: Max array size
268  *
269  * Fills in a scatterlist array with page references for a passed
270  * virtual address.
271  *
272  * Returns the number of scatterlist structs in array used
273  */
274 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
275                         int sg_size)
276 {
277         int i = 0;
278         struct page *pg;
279         int offset;
280         int remainder_of_page;
281
282         while (size > 0 && i < sg_size) {
283                 pg = virt_to_page(addr);
284                 offset = offset_in_page(addr);
285                 if (sg) {
286                         sg[i].page = pg;
287                         sg[i].offset = offset;
288                 }
289                 remainder_of_page = PAGE_CACHE_SIZE - offset;
290                 if (size >= remainder_of_page) {
291                         if (sg)
292                                 sg[i].length = remainder_of_page;
293                         addr += remainder_of_page;
294                         size -= remainder_of_page;
295                 } else {
296                         if (sg)
297                                 sg[i].length = size;
298                         addr += size;
299                         size = 0;
300                 }
301                 i++;
302         }
303         if (size > 0)
304                 return -ENOMEM;
305         return i;
306 }
307
308 /**
309  * encrypt_scatterlist
310  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
311  * @dest_sg: Destination of encrypted data
312  * @src_sg: Data to be encrypted
313  * @size: Length of data to be encrypted
314  * @iv: iv to use during encryption
315  *
316  * Returns the number of bytes encrypted; negative value on error
317  */
318 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
319                                struct scatterlist *dest_sg,
320                                struct scatterlist *src_sg, int size,
321                                unsigned char *iv)
322 {
323         struct blkcipher_desc desc = {
324                 .tfm = crypt_stat->tfm,
325                 .info = iv,
326                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
327         };
328         int rc = 0;
329
330         BUG_ON(!crypt_stat || !crypt_stat->tfm
331                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
332         if (unlikely(ecryptfs_verbosity > 0)) {
333                 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
334                                 crypt_stat->key_size);
335                 ecryptfs_dump_hex(crypt_stat->key,
336                                   crypt_stat->key_size);
337         }
338         /* Consider doing this once, when the file is opened */
339         mutex_lock(&crypt_stat->cs_tfm_mutex);
340         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
341                                      crypt_stat->key_size);
342         if (rc) {
343                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
344                                 rc);
345                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
346                 rc = -EINVAL;
347                 goto out;
348         }
349         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
350         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
351         mutex_unlock(&crypt_stat->cs_tfm_mutex);
352 out:
353         return rc;
354 }
355
356 static void
357 ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
358                                          int *byte_offset,
359                                          struct ecryptfs_crypt_stat *crypt_stat,
360                                          unsigned long extent_num)
361 {
362         unsigned long lower_extent_num;
363         int extents_occupied_by_headers_at_front;
364         int bytes_occupied_by_headers_at_front;
365         int extent_offset;
366         int extents_per_page;
367
368         bytes_occupied_by_headers_at_front =
369                 ( crypt_stat->header_extent_size
370                   * crypt_stat->num_header_extents_at_front );
371         extents_occupied_by_headers_at_front =
372                 ( bytes_occupied_by_headers_at_front
373                   / crypt_stat->extent_size );
374         lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
375         extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
376         (*lower_page_idx) = lower_extent_num / extents_per_page;
377         extent_offset = lower_extent_num % extents_per_page;
378         (*byte_offset) = extent_offset * crypt_stat->extent_size;
379         ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = "
380                         "[%d]\n", crypt_stat->header_extent_size);
381         ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
382                         "num_header_extents_at_front = [%d]\n",
383                         crypt_stat->num_header_extents_at_front);
384         ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
385                         "front = [%d]\n", extents_occupied_by_headers_at_front);
386         ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
387                         lower_extent_num);
388         ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
389                         extents_per_page);
390         ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
391                         (*lower_page_idx));
392         ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
393                         extent_offset);
394         ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
395                         (*byte_offset));
396 }
397
398 static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
399                                    struct page *lower_page,
400                                    struct inode *lower_inode,
401                                    int byte_offset_in_page, int bytes_to_write)
402 {
403         int rc = 0;
404
405         if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
406                 rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
407                                                 ctx->param.lower_file,
408                                                 byte_offset_in_page,
409                                                 bytes_to_write);
410                 if (rc) {
411                         ecryptfs_printk(KERN_ERR, "Error calling lower "
412                                         "commit; rc = [%d]\n", rc);
413                         goto out;
414                 }
415         } else {
416                 rc = ecryptfs_writepage_and_release_lower_page(lower_page,
417                                                                lower_inode,
418                                                                ctx->param.wbc);
419                 if (rc) {
420                         ecryptfs_printk(KERN_ERR, "Error calling lower "
421                                         "writepage(); rc = [%d]\n", rc);
422                         goto out;
423                 }
424         }
425 out:
426         return rc;
427 }
428
429 static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
430                                  struct page **lower_page,
431                                  struct inode *lower_inode,
432                                  unsigned long lower_page_idx,
433                                  int byte_offset_in_page)
434 {
435         int rc = 0;
436
437         if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
438                 /* TODO: Limit this to only the data extents that are
439                  * needed */
440                 rc = ecryptfs_get_lower_page(lower_page, lower_inode,
441                                              ctx->param.lower_file,
442                                              lower_page_idx,
443                                              byte_offset_in_page,
444                                              (PAGE_CACHE_SIZE
445                                               - byte_offset_in_page));
446                 if (rc) {
447                         ecryptfs_printk(
448                                 KERN_ERR, "Error attempting to grab, map, "
449                                 "and prepare_write lower page with index "
450                                 "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
451                         goto out;
452                 }
453         } else {
454                 *lower_page = grab_cache_page(lower_inode->i_mapping,
455                                               lower_page_idx);
456                 if (!(*lower_page)) {
457                         rc = -EINVAL;
458                         ecryptfs_printk(
459                                 KERN_ERR, "Error attempting to grab and map "
460                                 "lower page with index [0x%.16x]; rc = [%d]\n",
461                                 lower_page_idx, rc);
462                         goto out;
463                 }
464         }
465 out:
466         return rc;
467 }
468
469 /**
470  * ecryptfs_encrypt_page
471  * @ctx: The context of the page
472  *
473  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
474  * that eCryptfs pages may straddle the lower pages -- for instance,
475  * if the file was created on a machine with an 8K page size
476  * (resulting in an 8K header), and then the file is copied onto a
477  * host with a 32K page size, then when reading page 0 of the eCryptfs
478  * file, 24K of page 0 of the lower file will be read and decrypted,
479  * and then 8K of page 1 of the lower file will be read and decrypted.
480  *
481  * The actual operations performed on each page depends on the
482  * contents of the ecryptfs_page_crypt_context struct.
483  *
484  * Returns zero on success; negative on error
485  */
486 int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
487 {
488         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
489         unsigned long base_extent;
490         unsigned long extent_offset = 0;
491         unsigned long lower_page_idx = 0;
492         unsigned long prior_lower_page_idx = 0;
493         struct page *lower_page;
494         struct inode *lower_inode;
495         struct ecryptfs_inode_info *inode_info;
496         struct ecryptfs_crypt_stat *crypt_stat;
497         int rc = 0;
498         int lower_byte_offset = 0;
499         int orig_byte_offset = 0;
500         int num_extents_per_page;
501 #define ECRYPTFS_PAGE_STATE_UNREAD    0
502 #define ECRYPTFS_PAGE_STATE_READ      1
503 #define ECRYPTFS_PAGE_STATE_MODIFIED  2
504 #define ECRYPTFS_PAGE_STATE_WRITTEN   3
505         int page_state;
506
507         lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
508         inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
509         crypt_stat = &inode_info->crypt_stat;
510         if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
511                 rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
512                                                  ctx->param.lower_file);
513                 if (rc)
514                         ecryptfs_printk(KERN_ERR, "Error attempting to copy "
515                                         "page at index [0x%.16x]\n",
516                                         ctx->page->index);
517                 goto out;
518         }
519         num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
520         base_extent = (ctx->page->index * num_extents_per_page);
521         page_state = ECRYPTFS_PAGE_STATE_UNREAD;
522         while (extent_offset < num_extents_per_page) {
523                 ecryptfs_extent_to_lwr_pg_idx_and_offset(
524                         &lower_page_idx, &lower_byte_offset, crypt_stat,
525                         (base_extent + extent_offset));
526                 if (prior_lower_page_idx != lower_page_idx
527                     && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
528                         rc = ecryptfs_write_out_page(ctx, lower_page,
529                                                      lower_inode,
530                                                      orig_byte_offset,
531                                                      (PAGE_CACHE_SIZE
532                                                       - orig_byte_offset));
533                         if (rc) {
534                                 ecryptfs_printk(KERN_ERR, "Error attempting "
535                                                 "to write out page; rc = [%d]"
536                                                 "\n", rc);
537                                 goto out;
538                         }
539                         page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
540                 }
541                 if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
542                     || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
543                         rc = ecryptfs_read_in_page(ctx, &lower_page,
544                                                    lower_inode, lower_page_idx,
545                                                    lower_byte_offset);
546                         if (rc) {
547                                 ecryptfs_printk(KERN_ERR, "Error attempting "
548                                                 "to read in lower page with "
549                                                 "index [0x%.16x]; rc = [%d]\n",
550                                                 lower_page_idx, rc);
551                                 goto out;
552                         }
553                         orig_byte_offset = lower_byte_offset;
554                         prior_lower_page_idx = lower_page_idx;
555                         page_state = ECRYPTFS_PAGE_STATE_READ;
556                 }
557                 BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
558                          || page_state == ECRYPTFS_PAGE_STATE_READ));
559                 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
560                                         (base_extent + extent_offset));
561                 if (rc) {
562                         ecryptfs_printk(KERN_ERR, "Error attempting to "
563                                         "derive IV for extent [0x%.16x]; "
564                                         "rc = [%d]\n",
565                                         (base_extent + extent_offset), rc);
566                         goto out;
567                 }
568                 if (unlikely(ecryptfs_verbosity > 0)) {
569                         ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
570                                         "with iv:\n");
571                         ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
572                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
573                                         "encryption:\n");
574                         ecryptfs_dump_hex((char *)
575                                           (page_address(ctx->page)
576                                            + (extent_offset
577                                               * crypt_stat->extent_size)), 8);
578                 }
579                 rc = ecryptfs_encrypt_page_offset(
580                         crypt_stat, lower_page, lower_byte_offset, ctx->page,
581                         (extent_offset * crypt_stat->extent_size),
582                         crypt_stat->extent_size, extent_iv);
583                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
584                                 "rc = [%d]\n",
585                                 (base_extent + extent_offset), rc);
586                 if (unlikely(ecryptfs_verbosity > 0)) {
587                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
588                                         "encryption:\n");
589                         ecryptfs_dump_hex((char *)(page_address(lower_page)
590                                                    + lower_byte_offset), 8);
591                 }
592                 page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
593                 extent_offset++;
594         }
595         BUG_ON(orig_byte_offset != 0);
596         rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
597                                      (lower_byte_offset
598                                       + crypt_stat->extent_size));
599         if (rc) {
600                 ecryptfs_printk(KERN_ERR, "Error attempting to write out "
601                                 "page; rc = [%d]\n", rc);
602                                 goto out;
603         }
604 out:
605         return rc;
606 }
607
608 /**
609  * ecryptfs_decrypt_page
610  * @file: The ecryptfs file
611  * @page: The page in ecryptfs to decrypt
612  *
613  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
614  * that eCryptfs pages may straddle the lower pages -- for instance,
615  * if the file was created on a machine with an 8K page size
616  * (resulting in an 8K header), and then the file is copied onto a
617  * host with a 32K page size, then when reading page 0 of the eCryptfs
618  * file, 24K of page 0 of the lower file will be read and decrypted,
619  * and then 8K of page 1 of the lower file will be read and decrypted.
620  *
621  * Returns zero on success; negative on error
622  */
623 int ecryptfs_decrypt_page(struct file *file, struct page *page)
624 {
625         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
626         unsigned long base_extent;
627         unsigned long extent_offset = 0;
628         unsigned long lower_page_idx = 0;
629         unsigned long prior_lower_page_idx = 0;
630         struct page *lower_page;
631         char *lower_page_virt = NULL;
632         struct inode *lower_inode;
633         struct ecryptfs_crypt_stat *crypt_stat;
634         int rc = 0;
635         int byte_offset;
636         int num_extents_per_page;
637         int page_state;
638
639         crypt_stat = &(ecryptfs_inode_to_private(
640                                page->mapping->host)->crypt_stat);
641         lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
642         if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
643                 rc = ecryptfs_do_readpage(file, page, page->index);
644                 if (rc)
645                         ecryptfs_printk(KERN_ERR, "Error attempting to copy "
646                                         "page at index [0x%.16x]\n",
647                                         page->index);
648                 goto out;
649         }
650         num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
651         base_extent = (page->index * num_extents_per_page);
652         lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
653                                            GFP_KERNEL);
654         if (!lower_page_virt) {
655                 rc = -ENOMEM;
656                 ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
657                                 "lower page(s)\n");
658                 goto out;
659         }
660         lower_page = virt_to_page(lower_page_virt);
661         page_state = ECRYPTFS_PAGE_STATE_UNREAD;
662         while (extent_offset < num_extents_per_page) {
663                 ecryptfs_extent_to_lwr_pg_idx_and_offset(
664                         &lower_page_idx, &byte_offset, crypt_stat,
665                         (base_extent + extent_offset));
666                 if (prior_lower_page_idx != lower_page_idx
667                     || page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
668                         rc = ecryptfs_do_readpage(file, lower_page,
669                                                   lower_page_idx);
670                         if (rc) {
671                                 ecryptfs_printk(KERN_ERR, "Error reading "
672                                                 "lower encrypted page; rc = "
673                                                 "[%d]\n", rc);
674                                 goto out;
675                         }
676                         prior_lower_page_idx = lower_page_idx;
677                         page_state = ECRYPTFS_PAGE_STATE_READ;
678                 }
679                 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
680                                         (base_extent + extent_offset));
681                 if (rc) {
682                         ecryptfs_printk(KERN_ERR, "Error attempting to "
683                                         "derive IV for extent [0x%.16x]; rc = "
684                                         "[%d]\n",
685                                         (base_extent + extent_offset), rc);
686                         goto out;
687                 }
688                 if (unlikely(ecryptfs_verbosity > 0)) {
689                         ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
690                                         "with iv:\n");
691                         ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
692                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
693                                         "decryption:\n");
694                         ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
695                 }
696                 rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
697                                                   (extent_offset
698                                                    * crypt_stat->extent_size),
699                                                   lower_page, byte_offset,
700                                                   crypt_stat->extent_size,
701                                                   extent_iv);
702                 if (rc != crypt_stat->extent_size) {
703                         ecryptfs_printk(KERN_ERR, "Error attempting to "
704                                         "decrypt extent [0x%.16x]\n",
705                                         (base_extent + extent_offset));
706                         goto out;
707                 }
708                 rc = 0;
709                 if (unlikely(ecryptfs_verbosity > 0)) {
710                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
711                                         "decryption:\n");
712                         ecryptfs_dump_hex((char *)(page_address(page)
713                                                    + byte_offset), 8);
714                 }
715                 extent_offset++;
716         }
717 out:
718         if (lower_page_virt)
719                 kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
720         return rc;
721 }
722
723 /**
724  * decrypt_scatterlist
725  *
726  * Returns the number of bytes decrypted; negative value on error
727  */
728 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
729                                struct scatterlist *dest_sg,
730                                struct scatterlist *src_sg, int size,
731                                unsigned char *iv)
732 {
733         struct blkcipher_desc desc = {
734                 .tfm = crypt_stat->tfm,
735                 .info = iv,
736                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
737         };
738         int rc = 0;
739
740         /* Consider doing this once, when the file is opened */
741         mutex_lock(&crypt_stat->cs_tfm_mutex);
742         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
743                                      crypt_stat->key_size);
744         if (rc) {
745                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
746                                 rc);
747                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
748                 rc = -EINVAL;
749                 goto out;
750         }
751         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
752         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
753         mutex_unlock(&crypt_stat->cs_tfm_mutex);
754         if (rc) {
755                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
756                                 rc);
757                 goto out;
758         }
759         rc = size;
760 out:
761         return rc;
762 }
763
764 /**
765  * ecryptfs_encrypt_page_offset
766  *
767  * Returns the number of bytes encrypted
768  */
769 static int
770 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
771                              struct page *dst_page, int dst_offset,
772                              struct page *src_page, int src_offset, int size,
773                              unsigned char *iv)
774 {
775         struct scatterlist src_sg, dst_sg;
776
777         src_sg.page = src_page;
778         src_sg.offset = src_offset;
779         src_sg.length = size;
780         dst_sg.page = dst_page;
781         dst_sg.offset = dst_offset;
782         dst_sg.length = size;
783         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
784 }
785
786 /**
787  * ecryptfs_decrypt_page_offset
788  *
789  * Returns the number of bytes decrypted
790  */
791 static int
792 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
793                              struct page *dst_page, int dst_offset,
794                              struct page *src_page, int src_offset, int size,
795                              unsigned char *iv)
796 {
797         struct scatterlist src_sg, dst_sg;
798
799         src_sg.page = src_page;
800         src_sg.offset = src_offset;
801         src_sg.length = size;
802         dst_sg.page = dst_page;
803         dst_sg.offset = dst_offset;
804         dst_sg.length = size;
805         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
806 }
807
808 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
809
810 /**
811  * ecryptfs_init_crypt_ctx
812  * @crypt_stat: Uninitilized crypt stats structure
813  *
814  * Initialize the crypto context.
815  *
816  * TODO: Performance: Keep a cache of initialized cipher contexts;
817  * only init if needed
818  */
819 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
820 {
821         char *full_alg_name;
822         int rc = -EINVAL;
823
824         if (!crypt_stat->cipher) {
825                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
826                 goto out;
827         }
828         ecryptfs_printk(KERN_DEBUG,
829                         "Initializing cipher [%s]; strlen = [%d]; "
830                         "key_size_bits = [%d]\n",
831                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
832                         crypt_stat->key_size << 3);
833         if (crypt_stat->tfm) {
834                 rc = 0;
835                 goto out;
836         }
837         mutex_lock(&crypt_stat->cs_tfm_mutex);
838         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
839                                                     crypt_stat->cipher, "cbc");
840         if (rc)
841                 goto out;
842         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
843                                                  CRYPTO_ALG_ASYNC);
844         kfree(full_alg_name);
845         if (IS_ERR(crypt_stat->tfm)) {
846                 rc = PTR_ERR(crypt_stat->tfm);
847                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
848                                 "Error initializing cipher [%s]\n",
849                                 crypt_stat->cipher);
850                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
851                 goto out;
852         }
853         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
854         mutex_unlock(&crypt_stat->cs_tfm_mutex);
855         rc = 0;
856 out:
857         return rc;
858 }
859
860 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
861 {
862         int extent_size_tmp;
863
864         crypt_stat->extent_mask = 0xFFFFFFFF;
865         crypt_stat->extent_shift = 0;
866         if (crypt_stat->extent_size == 0)
867                 return;
868         extent_size_tmp = crypt_stat->extent_size;
869         while ((extent_size_tmp & 0x01) == 0) {
870                 extent_size_tmp >>= 1;
871                 crypt_stat->extent_mask <<= 1;
872                 crypt_stat->extent_shift++;
873         }
874 }
875
876 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
877 {
878         /* Default values; may be overwritten as we are parsing the
879          * packets. */
880         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
881         set_extent_mask_and_shift(crypt_stat);
882         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
883         if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
884                 crypt_stat->header_extent_size =
885                         ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
886         } else
887                 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
888         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
889                 crypt_stat->num_header_extents_at_front = 0;
890         else
891                 crypt_stat->num_header_extents_at_front = 1;
892 }
893
894 /**
895  * ecryptfs_compute_root_iv
896  * @crypt_stats
897  *
898  * On error, sets the root IV to all 0's.
899  */
900 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
901 {
902         int rc = 0;
903         char dst[MD5_DIGEST_SIZE];
904
905         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
906         BUG_ON(crypt_stat->iv_bytes <= 0);
907         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
908                 rc = -EINVAL;
909                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
910                                 "cannot generate root IV\n");
911                 goto out;
912         }
913         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
914                                     crypt_stat->key_size);
915         if (rc) {
916                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
917                                 "MD5 while generating root IV\n");
918                 goto out;
919         }
920         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
921 out:
922         if (rc) {
923                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
924                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
925         }
926         return rc;
927 }
928
929 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
930 {
931         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
932         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
933         ecryptfs_compute_root_iv(crypt_stat);
934         if (unlikely(ecryptfs_verbosity > 0)) {
935                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
936                 ecryptfs_dump_hex(crypt_stat->key,
937                                   crypt_stat->key_size);
938         }
939 }
940
941 /**
942  * ecryptfs_copy_mount_wide_flags_to_inode_flags
943  *
944  * This function propagates the mount-wide flags to individual inode
945  * flags.
946  */
947 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
948         struct ecryptfs_crypt_stat *crypt_stat,
949         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
950 {
951         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
952                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
953         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
954                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
955 }
956
957 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
958         struct ecryptfs_crypt_stat *crypt_stat,
959         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
960 {
961         struct ecryptfs_global_auth_tok *global_auth_tok;
962         int rc = 0;
963
964         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
965         list_for_each_entry(global_auth_tok,
966                             &mount_crypt_stat->global_auth_tok_list,
967                             mount_crypt_stat_list) {
968                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
969                 if (rc) {
970                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
971                         mutex_unlock(
972                                 &mount_crypt_stat->global_auth_tok_list_mutex);
973                         goto out;
974                 }
975         }
976         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
977 out:
978         return rc;
979 }
980
981 /**
982  * ecryptfs_set_default_crypt_stat_vals
983  * @crypt_stat
984  *
985  * Default values in the event that policy does not override them.
986  */
987 static void ecryptfs_set_default_crypt_stat_vals(
988         struct ecryptfs_crypt_stat *crypt_stat,
989         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
990 {
991         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
992                                                       mount_crypt_stat);
993         ecryptfs_set_default_sizes(crypt_stat);
994         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
995         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
996         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
997         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
998         crypt_stat->mount_crypt_stat = mount_crypt_stat;
999 }
1000
1001 /**
1002  * ecryptfs_new_file_context
1003  * @ecryptfs_dentry
1004  *
1005  * If the crypto context for the file has not yet been established,
1006  * this is where we do that.  Establishing a new crypto context
1007  * involves the following decisions:
1008  *  - What cipher to use?
1009  *  - What set of authentication tokens to use?
1010  * Here we just worry about getting enough information into the
1011  * authentication tokens so that we know that they are available.
1012  * We associate the available authentication tokens with the new file
1013  * via the set of signatures in the crypt_stat struct.  Later, when
1014  * the headers are actually written out, we may again defer to
1015  * userspace to perform the encryption of the session key; for the
1016  * foreseeable future, this will be the case with public key packets.
1017  *
1018  * Returns zero on success; non-zero otherwise
1019  */
1020 /* Associate an authentication token(s) with the file */
1021 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
1022 {
1023         struct ecryptfs_crypt_stat *crypt_stat =
1024             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1025         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1026             &ecryptfs_superblock_to_private(
1027                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
1028         int cipher_name_len;
1029         int rc = 0;
1030
1031         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
1032         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1033         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1034                                                       mount_crypt_stat);
1035         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1036                                                          mount_crypt_stat);
1037         if (rc) {
1038                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1039                        "to the inode key sigs; rc = [%d]\n", rc);
1040                 goto out;
1041         }
1042         cipher_name_len =
1043                 strlen(mount_crypt_stat->global_default_cipher_name);
1044         memcpy(crypt_stat->cipher,
1045                mount_crypt_stat->global_default_cipher_name,
1046                cipher_name_len);
1047         crypt_stat->cipher[cipher_name_len] = '\0';
1048         crypt_stat->key_size =
1049                 mount_crypt_stat->global_default_cipher_key_size;
1050         ecryptfs_generate_new_key(crypt_stat);
1051         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1052         if (rc)
1053                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1054                                 "context for cipher [%s]: rc = [%d]\n",
1055                                 crypt_stat->cipher, rc);
1056 out:
1057         return rc;
1058 }
1059
1060 /**
1061  * contains_ecryptfs_marker - check for the ecryptfs marker
1062  * @data: The data block in which to check
1063  *
1064  * Returns one if marker found; zero if not found
1065  */
1066 static int contains_ecryptfs_marker(char *data)
1067 {
1068         u32 m_1, m_2;
1069
1070         memcpy(&m_1, data, 4);
1071         m_1 = be32_to_cpu(m_1);
1072         memcpy(&m_2, (data + 4), 4);
1073         m_2 = be32_to_cpu(m_2);
1074         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1075                 return 1;
1076         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1077                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1078                         MAGIC_ECRYPTFS_MARKER);
1079         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1080                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1081         return 0;
1082 }
1083
1084 struct ecryptfs_flag_map_elem {
1085         u32 file_flag;
1086         u32 local_flag;
1087 };
1088
1089 /* Add support for additional flags by adding elements here. */
1090 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1091         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1092         {0x00000002, ECRYPTFS_ENCRYPTED},
1093         {0x00000004, ECRYPTFS_METADATA_IN_XATTR}
1094 };
1095
1096 /**
1097  * ecryptfs_process_flags
1098  * @crypt_stat
1099  * @page_virt: Source data to be parsed
1100  * @bytes_read: Updated with the number of bytes read
1101  *
1102  * Returns zero on success; non-zero if the flag set is invalid
1103  */
1104 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1105                                   char *page_virt, int *bytes_read)
1106 {
1107         int rc = 0;
1108         int i;
1109         u32 flags;
1110
1111         memcpy(&flags, page_virt, 4);
1112         flags = be32_to_cpu(flags);
1113         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1114                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1115                 if (flags & ecryptfs_flag_map[i].file_flag) {
1116                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1117                 } else
1118                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1119         /* Version is in top 8 bits of the 32-bit flag vector */
1120         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1121         (*bytes_read) = 4;
1122         return rc;
1123 }
1124
1125 /**
1126  * write_ecryptfs_marker
1127  * @page_virt: The pointer to in a page to begin writing the marker
1128  * @written: Number of bytes written
1129  *
1130  * Marker = 0x3c81b7f5
1131  */
1132 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1133 {
1134         u32 m_1, m_2;
1135
1136         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1137         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1138         m_1 = cpu_to_be32(m_1);
1139         memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1140         m_2 = cpu_to_be32(m_2);
1141         memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1142                (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1143         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1144 }
1145
1146 static void
1147 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1148                      size_t *written)
1149 {
1150         u32 flags = 0;
1151         int i;
1152
1153         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1154                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1155                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1156                         flags |= ecryptfs_flag_map[i].file_flag;
1157         /* Version is in top 8 bits of the 32-bit flag vector */
1158         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1159         flags = cpu_to_be32(flags);
1160         memcpy(page_virt, &flags, 4);
1161         (*written) = 4;
1162 }
1163
1164 struct ecryptfs_cipher_code_str_map_elem {
1165         char cipher_str[16];
1166         u16 cipher_code;
1167 };
1168
1169 /* Add support for additional ciphers by adding elements here. The
1170  * cipher_code is whatever OpenPGP applicatoins use to identify the
1171  * ciphers. List in order of probability. */
1172 static struct ecryptfs_cipher_code_str_map_elem
1173 ecryptfs_cipher_code_str_map[] = {
1174         {"aes",RFC2440_CIPHER_AES_128 },
1175         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1176         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1177         {"cast5", RFC2440_CIPHER_CAST_5},
1178         {"twofish", RFC2440_CIPHER_TWOFISH},
1179         {"cast6", RFC2440_CIPHER_CAST_6},
1180         {"aes", RFC2440_CIPHER_AES_192},
1181         {"aes", RFC2440_CIPHER_AES_256}
1182 };
1183
1184 /**
1185  * ecryptfs_code_for_cipher_string
1186  * @str: The string representing the cipher name
1187  *
1188  * Returns zero on no match, or the cipher code on match
1189  */
1190 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1191 {
1192         int i;
1193         u16 code = 0;
1194         struct ecryptfs_cipher_code_str_map_elem *map =
1195                 ecryptfs_cipher_code_str_map;
1196
1197         if (strcmp(crypt_stat->cipher, "aes") == 0) {
1198                 switch (crypt_stat->key_size) {
1199                 case 16:
1200                         code = RFC2440_CIPHER_AES_128;
1201                         break;
1202                 case 24:
1203                         code = RFC2440_CIPHER_AES_192;
1204                         break;
1205                 case 32:
1206                         code = RFC2440_CIPHER_AES_256;
1207                 }
1208         } else {
1209                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1210                         if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1211                                 code = map[i].cipher_code;
1212                                 break;
1213                         }
1214         }
1215         return code;
1216 }
1217
1218 /**
1219  * ecryptfs_cipher_code_to_string
1220  * @str: Destination to write out the cipher name
1221  * @cipher_code: The code to convert to cipher name string
1222  *
1223  * Returns zero on success
1224  */
1225 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1226 {
1227         int rc = 0;
1228         int i;
1229
1230         str[0] = '\0';
1231         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1232                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1233                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1234         if (str[0] == '\0') {
1235                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1236                                 "[%d]\n", cipher_code);
1237                 rc = -EINVAL;
1238         }
1239         return rc;
1240 }
1241
1242 /**
1243  * ecryptfs_read_header_region
1244  * @data
1245  * @dentry
1246  * @nd
1247  *
1248  * Returns zero on success; non-zero otherwise
1249  */
1250 static int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1251                                        struct vfsmount *mnt)
1252 {
1253         struct file *lower_file;
1254         mm_segment_t oldfs;
1255         int rc;
1256
1257         if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
1258                                            O_RDONLY))) {
1259                 printk(KERN_ERR
1260                        "Error opening lower_file to read header region\n");
1261                 goto out;
1262         }
1263         lower_file->f_pos = 0;
1264         oldfs = get_fs();
1265         set_fs(get_ds());
1266         rc = lower_file->f_op->read(lower_file, (char __user *)data,
1267                               ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
1268         set_fs(oldfs);
1269         if ((rc = ecryptfs_close_lower_file(lower_file))) {
1270                 printk(KERN_ERR "Error closing lower_file\n");
1271                 goto out;
1272         }
1273         rc = 0;
1274 out:
1275         return rc;
1276 }
1277
1278 int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
1279                                              struct vfsmount *mnt)
1280 {
1281         int rc;
1282
1283         rc = ecryptfs_read_header_region(data, dentry, mnt);
1284         if (rc)
1285                 goto out;
1286         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES))
1287                 rc = -EINVAL;
1288 out:
1289         return rc;
1290 }
1291
1292
1293 void
1294 ecryptfs_write_header_metadata(char *virt,
1295                                struct ecryptfs_crypt_stat *crypt_stat,
1296                                size_t *written)
1297 {
1298         u32 header_extent_size;
1299         u16 num_header_extents_at_front;
1300
1301         header_extent_size = (u32)crypt_stat->header_extent_size;
1302         num_header_extents_at_front =
1303                 (u16)crypt_stat->num_header_extents_at_front;
1304         header_extent_size = cpu_to_be32(header_extent_size);
1305         memcpy(virt, &header_extent_size, 4);
1306         virt += 4;
1307         num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1308         memcpy(virt, &num_header_extents_at_front, 2);
1309         (*written) = 6;
1310 }
1311
1312 struct kmem_cache *ecryptfs_header_cache_0;
1313 struct kmem_cache *ecryptfs_header_cache_1;
1314 struct kmem_cache *ecryptfs_header_cache_2;
1315
1316 /**
1317  * ecryptfs_write_headers_virt
1318  * @page_virt
1319  * @crypt_stat
1320  * @ecryptfs_dentry
1321  *
1322  * Format version: 1
1323  *
1324  *   Header Extent:
1325  *     Octets 0-7:        Unencrypted file size (big-endian)
1326  *     Octets 8-15:       eCryptfs special marker
1327  *     Octets 16-19:      Flags
1328  *      Octet 16:         File format version number (between 0 and 255)
1329  *      Octets 17-18:     Reserved
1330  *      Octet 19:         Bit 1 (lsb): Reserved
1331  *                        Bit 2: Encrypted?
1332  *                        Bits 3-8: Reserved
1333  *     Octets 20-23:      Header extent size (big-endian)
1334  *     Octets 24-25:      Number of header extents at front of file
1335  *                        (big-endian)
1336  *     Octet  26:         Begin RFC 2440 authentication token packet set
1337  *   Data Extent 0:
1338  *     Lower data (CBC encrypted)
1339  *   Data Extent 1:
1340  *     Lower data (CBC encrypted)
1341  *   ...
1342  *
1343  * Returns zero on success
1344  */
1345 static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
1346                                        struct ecryptfs_crypt_stat *crypt_stat,
1347                                        struct dentry *ecryptfs_dentry)
1348 {
1349         int rc;
1350         size_t written;
1351         size_t offset;
1352
1353         offset = ECRYPTFS_FILE_SIZE_BYTES;
1354         write_ecryptfs_marker((page_virt + offset), &written);
1355         offset += written;
1356         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1357         offset += written;
1358         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1359                                        &written);
1360         offset += written;
1361         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1362                                               ecryptfs_dentry, &written,
1363                                               PAGE_CACHE_SIZE - offset);
1364         if (rc)
1365                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1366                                 "set; rc = [%d]\n", rc);
1367         if (size) {
1368                 offset += written;
1369                 *size = offset;
1370         }
1371         return rc;
1372 }
1373
1374 static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
1375                                                struct file *lower_file,
1376                                                char *page_virt)
1377 {
1378         mm_segment_t oldfs;
1379         int current_header_page;
1380         int header_pages;
1381         ssize_t size;
1382         int rc = 0;
1383
1384         lower_file->f_pos = 0;
1385         oldfs = get_fs();
1386         set_fs(get_ds());
1387         size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE,
1388                          &lower_file->f_pos);
1389         if (size < 0) {
1390                 rc = (int)size;
1391                 printk(KERN_ERR "Error attempting to write lower page; "
1392                        "rc = [%d]\n", rc);
1393                 set_fs(oldfs);
1394                 goto out;
1395         }
1396         header_pages = ((crypt_stat->header_extent_size
1397                          * crypt_stat->num_header_extents_at_front)
1398                         / PAGE_CACHE_SIZE);
1399         memset(page_virt, 0, PAGE_CACHE_SIZE);
1400         current_header_page = 1;
1401         while (current_header_page < header_pages) {
1402                 size = vfs_write(lower_file, (char __user *)page_virt,
1403                                  PAGE_CACHE_SIZE, &lower_file->f_pos);
1404                 if (size < 0) {
1405                         rc = (int)size;
1406                         printk(KERN_ERR "Error attempting to write lower page; "
1407                                "rc = [%d]\n", rc);
1408                         set_fs(oldfs);
1409                         goto out;
1410                 }
1411                 current_header_page++;
1412         }
1413         set_fs(oldfs);
1414 out:
1415         return rc;
1416 }
1417
1418 static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1419                                             struct ecryptfs_crypt_stat *crypt_stat,
1420                                             char *page_virt, size_t size)
1421 {
1422         int rc;
1423
1424         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1425                                size, 0);
1426         return rc;
1427 }
1428
1429 /**
1430  * ecryptfs_write_metadata
1431  * @lower_file: The lower file struct, which was returned from dentry_open
1432  *
1433  * Write the file headers out.  This will likely involve a userspace
1434  * callout, in which the session key is encrypted with one or more
1435  * public keys and/or the passphrase necessary to do the encryption is
1436  * retrieved via a prompt.  Exactly what happens at this point should
1437  * be policy-dependent.
1438  *
1439  * Returns zero on success; non-zero on error
1440  */
1441 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1442                             struct file *lower_file)
1443 {
1444         struct ecryptfs_crypt_stat *crypt_stat;
1445         char *page_virt;
1446         size_t size;
1447         int rc = 0;
1448
1449         crypt_stat = &ecryptfs_inode_to_private(
1450                 ecryptfs_dentry->d_inode)->crypt_stat;
1451         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1452                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1453                         ecryptfs_printk(KERN_DEBUG, "Key is "
1454                                         "invalid; bailing out\n");
1455                         rc = -EINVAL;
1456                         goto out;
1457                 }
1458         } else {
1459                 rc = -EINVAL;
1460                 ecryptfs_printk(KERN_WARNING,
1461                                 "Called with crypt_stat->encrypted == 0\n");
1462                 goto out;
1463         }
1464         /* Released in this function */
1465         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
1466         if (!page_virt) {
1467                 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1468                 rc = -ENOMEM;
1469                 goto out;
1470         }
1471         rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
1472                                          ecryptfs_dentry);
1473         if (unlikely(rc)) {
1474                 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1475                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1476                 goto out_free;
1477         }
1478         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1479                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
1480                                                       crypt_stat, page_virt,
1481                                                       size);
1482         else
1483                 rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file,
1484                                                          page_virt);
1485         if (rc) {
1486                 printk(KERN_ERR "Error writing metadata out to lower file; "
1487                        "rc = [%d]\n", rc);
1488                 goto out_free;
1489         }
1490 out_free:
1491         kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1492 out:
1493         return rc;
1494 }
1495
1496 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1497 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1498 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1499                                  char *virt, int *bytes_read,
1500                                  int validate_header_size)
1501 {
1502         int rc = 0;
1503         u32 header_extent_size;
1504         u16 num_header_extents_at_front;
1505
1506         memcpy(&header_extent_size, virt, 4);
1507         header_extent_size = be32_to_cpu(header_extent_size);
1508         virt += 4;
1509         memcpy(&num_header_extents_at_front, virt, 2);
1510         num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1511         crypt_stat->header_extent_size = (int)header_extent_size;
1512         crypt_stat->num_header_extents_at_front =
1513                 (int)num_header_extents_at_front;
1514         (*bytes_read) = 6;
1515         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1516             && ((crypt_stat->header_extent_size
1517                  * crypt_stat->num_header_extents_at_front)
1518                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1519                 rc = -EINVAL;
1520                 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1521                                 "[%d]\n", crypt_stat->header_extent_size);
1522         }
1523         return rc;
1524 }
1525
1526 /**
1527  * set_default_header_data
1528  *
1529  * For version 0 file format; this function is only for backwards
1530  * compatibility for files created with the prior versions of
1531  * eCryptfs.
1532  */
1533 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1534 {
1535         crypt_stat->header_extent_size = 4096;
1536         crypt_stat->num_header_extents_at_front = 1;
1537 }
1538
1539 /**
1540  * ecryptfs_read_headers_virt
1541  *
1542  * Read/parse the header data. The header format is detailed in the
1543  * comment block for the ecryptfs_write_headers_virt() function.
1544  *
1545  * Returns zero on success
1546  */
1547 static int ecryptfs_read_headers_virt(char *page_virt,
1548                                       struct ecryptfs_crypt_stat *crypt_stat,
1549                                       struct dentry *ecryptfs_dentry,
1550                                       int validate_header_size)
1551 {
1552         int rc = 0;
1553         int offset;
1554         int bytes_read;
1555
1556         ecryptfs_set_default_sizes(crypt_stat);
1557         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1558                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1559         offset = ECRYPTFS_FILE_SIZE_BYTES;
1560         rc = contains_ecryptfs_marker(page_virt + offset);
1561         if (rc == 0) {
1562                 rc = -EINVAL;
1563                 goto out;
1564         }
1565         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1566         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1567                                     &bytes_read);
1568         if (rc) {
1569                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1570                 goto out;
1571         }
1572         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1573                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1574                                 "file version [%d] is supported by this "
1575                                 "version of eCryptfs\n",
1576                                 crypt_stat->file_version,
1577                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1578                 rc = -EINVAL;
1579                 goto out;
1580         }
1581         offset += bytes_read;
1582         if (crypt_stat->file_version >= 1) {
1583                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1584                                            &bytes_read, validate_header_size);
1585                 if (rc) {
1586                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1587                                         "metadata; rc = [%d]\n", rc);
1588                 }
1589                 offset += bytes_read;
1590         } else
1591                 set_default_header_data(crypt_stat);
1592         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1593                                        ecryptfs_dentry);
1594 out:
1595         return rc;
1596 }
1597
1598 /**
1599  * ecryptfs_read_xattr_region
1600  *
1601  * Attempts to read the crypto metadata from the extended attribute
1602  * region of the lower file.
1603  */
1604 int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry)
1605 {
1606         ssize_t size;
1607         int rc = 0;
1608
1609         size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME,
1610                                  page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1611         if (size < 0) {
1612                 printk(KERN_DEBUG "Error attempting to read the [%s] "
1613                        "xattr from the lower file; return value = [%zd]\n",
1614                        ECRYPTFS_XATTR_NAME, size);
1615                 rc = -EINVAL;
1616                 goto out;
1617         }
1618 out:
1619         return rc;
1620 }
1621
1622 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1623                                             struct dentry *ecryptfs_dentry)
1624 {
1625         int rc;
1626
1627         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry);
1628         if (rc)
1629                 goto out;
1630         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1631                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1632                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1633                 rc = -EINVAL;
1634         }
1635 out:
1636         return rc;
1637 }
1638
1639 /**
1640  * ecryptfs_read_metadata
1641  *
1642  * Common entry point for reading file metadata. From here, we could
1643  * retrieve the header information from the header region of the file,
1644  * the xattr region of the file, or some other repostory that is
1645  * stored separately from the file itself. The current implementation
1646  * supports retrieving the metadata information from the file contents
1647  * and from the xattr region.
1648  *
1649  * Returns zero if valid headers found and parsed; non-zero otherwise
1650  */
1651 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
1652                            struct file *lower_file)
1653 {
1654         int rc = 0;
1655         char *page_virt = NULL;
1656         mm_segment_t oldfs;
1657         ssize_t bytes_read;
1658         struct ecryptfs_crypt_stat *crypt_stat =
1659             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1660         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1661                 &ecryptfs_superblock_to_private(
1662                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1663
1664         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1665                                                       mount_crypt_stat);
1666         /* Read the first page from the underlying file */
1667         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1668         if (!page_virt) {
1669                 rc = -ENOMEM;
1670                 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1671                 goto out;
1672         }
1673         lower_file->f_pos = 0;
1674         oldfs = get_fs();
1675         set_fs(get_ds());
1676         bytes_read = lower_file->f_op->read(lower_file,
1677                                             (char __user *)page_virt,
1678                                             ECRYPTFS_DEFAULT_EXTENT_SIZE,
1679                                             &lower_file->f_pos);
1680         set_fs(oldfs);
1681         if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1682                 rc = -EINVAL;
1683                 goto out;
1684         }
1685         rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1686                                         ecryptfs_dentry,
1687                                         ECRYPTFS_VALIDATE_HEADER_SIZE);
1688         if (rc) {
1689                 rc = ecryptfs_read_xattr_region(page_virt,
1690                                                 ecryptfs_dentry);
1691                 if (rc) {
1692                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1693                                "file header region or xattr region\n");
1694                         rc = -EINVAL;
1695                         goto out;
1696                 }
1697                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1698                                                 ecryptfs_dentry,
1699                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1700                 if (rc) {
1701                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1702                                "file xattr region either\n");
1703                         rc = -EINVAL;
1704                 }
1705                 if (crypt_stat->mount_crypt_stat->flags
1706                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1707                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1708                 } else {
1709                         printk(KERN_WARNING "Attempt to access file with "
1710                                "crypto metadata only in the extended attribute "
1711                                "region, but eCryptfs was mounted without "
1712                                "xattr support enabled. eCryptfs will not treat "
1713                                "this like an encrypted file.\n");
1714                         rc = -EINVAL;
1715                 }
1716         }
1717 out:
1718         if (page_virt) {
1719                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1720                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1721         }
1722         return rc;
1723 }
1724
1725 /**
1726  * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1727  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1728  * @name: The plaintext name
1729  * @length: The length of the plaintext
1730  * @encoded_name: The encypted name
1731  *
1732  * Encrypts and encodes a filename into something that constitutes a
1733  * valid filename for a filesystem, with printable characters.
1734  *
1735  * We assume that we have a properly initialized crypto context,
1736  * pointed to by crypt_stat->tfm.
1737  *
1738  * TODO: Implement filename decoding and decryption here, in place of
1739  * memcpy. We are keeping the framework around for now to (1)
1740  * facilitate testing of the components needed to implement filename
1741  * encryption and (2) to provide a code base from which other
1742  * developers in the community can easily implement this feature.
1743  *
1744  * Returns the length of encoded filename; negative if error
1745  */
1746 int
1747 ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1748                          const char *name, int length, char **encoded_name)
1749 {
1750         int error = 0;
1751
1752         (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1753         if (!(*encoded_name)) {
1754                 error = -ENOMEM;
1755                 goto out;
1756         }
1757         /* TODO: Filename encryption is a scheduled feature for a
1758          * future version of eCryptfs. This function is here only for
1759          * the purpose of providing a framework for other developers
1760          * to easily implement filename encryption. Hint: Replace this
1761          * memcpy() with a call to encrypt and encode the
1762          * filename, the set the length accordingly. */
1763         memcpy((void *)(*encoded_name), (void *)name, length);
1764         (*encoded_name)[length] = '\0';
1765         error = length + 1;
1766 out:
1767         return error;
1768 }
1769
1770 /**
1771  * ecryptfs_decode_filename - converts the cipher text name to plaintext
1772  * @crypt_stat: The crypt_stat struct associated with the file
1773  * @name: The filename in cipher text
1774  * @length: The length of the cipher text name
1775  * @decrypted_name: The plaintext name
1776  *
1777  * Decodes and decrypts the filename.
1778  *
1779  * We assume that we have a properly initialized crypto context,
1780  * pointed to by crypt_stat->tfm.
1781  *
1782  * TODO: Implement filename decoding and decryption here, in place of
1783  * memcpy. We are keeping the framework around for now to (1)
1784  * facilitate testing of the components needed to implement filename
1785  * encryption and (2) to provide a code base from which other
1786  * developers in the community can easily implement this feature.
1787  *
1788  * Returns the length of decoded filename; negative if error
1789  */
1790 int
1791 ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1792                          const char *name, int length, char **decrypted_name)
1793 {
1794         int error = 0;
1795
1796         (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1797         if (!(*decrypted_name)) {
1798                 error = -ENOMEM;
1799                 goto out;
1800         }
1801         /* TODO: Filename encryption is a scheduled feature for a
1802          * future version of eCryptfs. This function is here only for
1803          * the purpose of providing a framework for other developers
1804          * to easily implement filename encryption. Hint: Replace this
1805          * memcpy() with a call to decode and decrypt the
1806          * filename, the set the length accordingly. */
1807         memcpy((void *)(*decrypted_name), (void *)name, length);
1808         (*decrypted_name)[length + 1] = '\0';   /* Only for convenience
1809                                                  * in printing out the
1810                                                  * string in debug
1811                                                  * messages */
1812         error = length;
1813 out:
1814         return error;
1815 }
1816
1817 /**
1818  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1819  * @key_tfm: Crypto context for key material, set by this function
1820  * @cipher_name: Name of the cipher
1821  * @key_size: Size of the key in bytes
1822  *
1823  * Returns zero on success. Any crypto_tfm structs allocated here
1824  * should be released by other functions, such as on a superblock put
1825  * event, regardless of whether this function succeeds for fails.
1826  */
1827 int
1828 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1829                             char *cipher_name, size_t *key_size)
1830 {
1831         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1832         char *full_alg_name;
1833         int rc;
1834
1835         *key_tfm = NULL;
1836         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1837                 rc = -EINVAL;
1838                 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1839                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1840                 goto out;
1841         }
1842         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1843                                                     "ecb");
1844         if (rc)
1845                 goto out;
1846         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1847         kfree(full_alg_name);
1848         if (IS_ERR(*key_tfm)) {
1849                 rc = PTR_ERR(*key_tfm);
1850                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1851                        "[%s]; rc = [%d]\n", cipher_name, rc);
1852                 goto out;
1853         }
1854         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1855         if (*key_size == 0) {
1856                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1857
1858                 *key_size = alg->max_keysize;
1859         }
1860         get_random_bytes(dummy_key, *key_size);
1861         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1862         if (rc) {
1863                 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1864                        "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
1865                 rc = -EINVAL;
1866                 goto out;
1867         }
1868 out:
1869         return rc;
1870 }
1871
1872 struct kmem_cache *ecryptfs_key_tfm_cache;
1873 struct list_head key_tfm_list;
1874 struct mutex key_tfm_list_mutex;
1875
1876 int ecryptfs_init_crypto(void)
1877 {
1878         mutex_init(&key_tfm_list_mutex);
1879         INIT_LIST_HEAD(&key_tfm_list);
1880         return 0;
1881 }
1882
1883 int ecryptfs_destroy_crypto(void)
1884 {
1885         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1886
1887         mutex_lock(&key_tfm_list_mutex);
1888         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1889                                  key_tfm_list) {
1890                 list_del(&key_tfm->key_tfm_list);
1891                 if (key_tfm->key_tfm)
1892                         crypto_free_blkcipher(key_tfm->key_tfm);
1893                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1894         }
1895         mutex_unlock(&key_tfm_list_mutex);
1896         return 0;
1897 }
1898
1899 int
1900 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1901                          size_t key_size)
1902 {
1903         struct ecryptfs_key_tfm *tmp_tfm;
1904         int rc = 0;
1905
1906         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1907         if (key_tfm != NULL)
1908                 (*key_tfm) = tmp_tfm;
1909         if (!tmp_tfm) {
1910                 rc = -ENOMEM;
1911                 printk(KERN_ERR "Error attempting to allocate from "
1912                        "ecryptfs_key_tfm_cache\n");
1913                 goto out;
1914         }
1915         mutex_init(&tmp_tfm->key_tfm_mutex);
1916         strncpy(tmp_tfm->cipher_name, cipher_name,
1917                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1918         tmp_tfm->key_size = key_size;
1919         if ((rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1920                                               tmp_tfm->cipher_name,
1921                                               &tmp_tfm->key_size))) {
1922                 printk(KERN_ERR "Error attempting to initialize key TFM "
1923                        "cipher with name = [%s]; rc = [%d]\n",
1924                        tmp_tfm->cipher_name, rc);
1925                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1926                 if (key_tfm != NULL)
1927                         (*key_tfm) = NULL;
1928                 goto out;
1929         }
1930         mutex_lock(&key_tfm_list_mutex);
1931         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1932         mutex_unlock(&key_tfm_list_mutex);
1933 out:
1934         return rc;
1935 }
1936
1937 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1938                                                struct mutex **tfm_mutex,
1939                                                char *cipher_name)
1940 {
1941         struct ecryptfs_key_tfm *key_tfm;
1942         int rc = 0;
1943
1944         (*tfm) = NULL;
1945         (*tfm_mutex) = NULL;
1946         mutex_lock(&key_tfm_list_mutex);
1947         list_for_each_entry(key_tfm, &key_tfm_list, key_tfm_list) {
1948                 if (strcmp(key_tfm->cipher_name, cipher_name) == 0) {
1949                         (*tfm) = key_tfm->key_tfm;
1950                         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1951                         mutex_unlock(&key_tfm_list_mutex);
1952                         goto out;
1953                 }
1954         }
1955         mutex_unlock(&key_tfm_list_mutex);
1956         if ((rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0))) {
1957                 printk(KERN_ERR "Error adding new key_tfm to list; rc = [%d]\n",
1958                        rc);
1959                 goto out;
1960         }
1961         (*tfm) = key_tfm->key_tfm;
1962         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1963 out:
1964         return rc;
1965 }