eCryptfs: don't encrypt file key with filename key
[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 <asm/unaligned.h>
37 #include "ecryptfs_kernel.h"
38
39 static int
40 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
41                              struct page *dst_page, int dst_offset,
42                              struct page *src_page, int src_offset, int size,
43                              unsigned char *iv);
44 static int
45 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
46                              struct page *dst_page, int dst_offset,
47                              struct page *src_page, int src_offset, int size,
48                              unsigned char *iv);
49
50 /**
51  * ecryptfs_to_hex
52  * @dst: Buffer to take hex character representation of contents of
53  *       src; must be at least of size (src_size * 2)
54  * @src: Buffer to be converted to a hex string respresentation
55  * @src_size: number of bytes to convert
56  */
57 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
58 {
59         int x;
60
61         for (x = 0; x < src_size; x++)
62                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
63 }
64
65 /**
66  * ecryptfs_from_hex
67  * @dst: Buffer to take the bytes from src hex; must be at least of
68  *       size (src_size / 2)
69  * @src: Buffer to be converted from a hex string respresentation to raw value
70  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
71  */
72 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
73 {
74         int x;
75         char tmp[3] = { 0, };
76
77         for (x = 0; x < dst_size; x++) {
78                 tmp[0] = src[x * 2];
79                 tmp[1] = src[x * 2 + 1];
80                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
81         }
82 }
83
84 /**
85  * ecryptfs_calculate_md5 - calculates the md5 of @src
86  * @dst: Pointer to 16 bytes of allocated memory
87  * @crypt_stat: Pointer to crypt_stat struct for the current inode
88  * @src: Data to be md5'd
89  * @len: Length of @src
90  *
91  * Uses the allocated crypto context that crypt_stat references to
92  * generate the MD5 sum of the contents of src.
93  */
94 static int ecryptfs_calculate_md5(char *dst,
95                                   struct ecryptfs_crypt_stat *crypt_stat,
96                                   char *src, int len)
97 {
98         struct scatterlist sg;
99         struct hash_desc desc = {
100                 .tfm = crypt_stat->hash_tfm,
101                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
102         };
103         int rc = 0;
104
105         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
106         sg_init_one(&sg, (u8 *)src, len);
107         if (!desc.tfm) {
108                 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
109                                              CRYPTO_ALG_ASYNC);
110                 if (IS_ERR(desc.tfm)) {
111                         rc = PTR_ERR(desc.tfm);
112                         ecryptfs_printk(KERN_ERR, "Error attempting to "
113                                         "allocate crypto context; rc = [%d]\n",
114                                         rc);
115                         goto out;
116                 }
117                 crypt_stat->hash_tfm = desc.tfm;
118         }
119         rc = crypto_hash_init(&desc);
120         if (rc) {
121                 printk(KERN_ERR
122                        "%s: Error initializing crypto hash; rc = [%d]\n",
123                        __func__, rc);
124                 goto out;
125         }
126         rc = crypto_hash_update(&desc, &sg, len);
127         if (rc) {
128                 printk(KERN_ERR
129                        "%s: Error updating crypto hash; rc = [%d]\n",
130                        __func__, rc);
131                 goto out;
132         }
133         rc = crypto_hash_final(&desc, dst);
134         if (rc) {
135                 printk(KERN_ERR
136                        "%s: Error finalizing crypto hash; rc = [%d]\n",
137                        __func__, rc);
138                 goto out;
139         }
140 out:
141         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
142         return rc;
143 }
144
145 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
146                                                   char *cipher_name,
147                                                   char *chaining_modifier)
148 {
149         int cipher_name_len = strlen(cipher_name);
150         int chaining_modifier_len = strlen(chaining_modifier);
151         int algified_name_len;
152         int rc;
153
154         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
155         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
156         if (!(*algified_name)) {
157                 rc = -ENOMEM;
158                 goto out;
159         }
160         snprintf((*algified_name), algified_name_len, "%s(%s)",
161                  chaining_modifier, cipher_name);
162         rc = 0;
163 out:
164         return rc;
165 }
166
167 /**
168  * ecryptfs_derive_iv
169  * @iv: destination for the derived iv vale
170  * @crypt_stat: Pointer to crypt_stat struct for the current inode
171  * @offset: Offset of the extent whose IV we are to derive
172  *
173  * Generate the initialization vector from the given root IV and page
174  * offset.
175  *
176  * Returns zero on success; non-zero on error.
177  */
178 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
179                        loff_t offset)
180 {
181         int rc = 0;
182         char dst[MD5_DIGEST_SIZE];
183         char src[ECRYPTFS_MAX_IV_BYTES + 16];
184
185         if (unlikely(ecryptfs_verbosity > 0)) {
186                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
187                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
188         }
189         /* TODO: It is probably secure to just cast the least
190          * significant bits of the root IV into an unsigned long and
191          * add the offset to that rather than go through all this
192          * hashing business. -Halcrow */
193         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
194         memset((src + crypt_stat->iv_bytes), 0, 16);
195         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
196         if (unlikely(ecryptfs_verbosity > 0)) {
197                 ecryptfs_printk(KERN_DEBUG, "source:\n");
198                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
199         }
200         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
201                                     (crypt_stat->iv_bytes + 16));
202         if (rc) {
203                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
204                                 "MD5 while generating IV for a page\n");
205                 goto out;
206         }
207         memcpy(iv, dst, crypt_stat->iv_bytes);
208         if (unlikely(ecryptfs_verbosity > 0)) {
209                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
210                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
211         }
212 out:
213         return rc;
214 }
215
216 /**
217  * ecryptfs_init_crypt_stat
218  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
219  *
220  * Initialize the crypt_stat structure.
221  */
222 void
223 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
224 {
225         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
226         INIT_LIST_HEAD(&crypt_stat->keysig_list);
227         mutex_init(&crypt_stat->keysig_list_mutex);
228         mutex_init(&crypt_stat->cs_mutex);
229         mutex_init(&crypt_stat->cs_tfm_mutex);
230         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
231         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
232 }
233
234 /**
235  * ecryptfs_destroy_crypt_stat
236  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
237  *
238  * Releases all memory associated with a crypt_stat struct.
239  */
240 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
241 {
242         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
243
244         if (crypt_stat->tfm)
245                 crypto_free_blkcipher(crypt_stat->tfm);
246         if (crypt_stat->hash_tfm)
247                 crypto_free_hash(crypt_stat->hash_tfm);
248         mutex_lock(&crypt_stat->keysig_list_mutex);
249         list_for_each_entry_safe(key_sig, key_sig_tmp,
250                                  &crypt_stat->keysig_list, crypt_stat_list) {
251                 list_del(&key_sig->crypt_stat_list);
252                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
253         }
254         mutex_unlock(&crypt_stat->keysig_list_mutex);
255         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
256 }
257
258 void ecryptfs_destroy_mount_crypt_stat(
259         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
260 {
261         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
262
263         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
264                 return;
265         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
266         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
267                                  &mount_crypt_stat->global_auth_tok_list,
268                                  mount_crypt_stat_list) {
269                 list_del(&auth_tok->mount_crypt_stat_list);
270                 mount_crypt_stat->num_global_auth_toks--;
271                 if (auth_tok->global_auth_tok_key
272                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
273                         key_put(auth_tok->global_auth_tok_key);
274                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
275         }
276         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
277         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
278 }
279
280 /**
281  * virt_to_scatterlist
282  * @addr: Virtual address
283  * @size: Size of data; should be an even multiple of the block size
284  * @sg: Pointer to scatterlist array; set to NULL to obtain only
285  *      the number of scatterlist structs required in array
286  * @sg_size: Max array size
287  *
288  * Fills in a scatterlist array with page references for a passed
289  * virtual address.
290  *
291  * Returns the number of scatterlist structs in array used
292  */
293 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
294                         int sg_size)
295 {
296         int i = 0;
297         struct page *pg;
298         int offset;
299         int remainder_of_page;
300
301         sg_init_table(sg, sg_size);
302
303         while (size > 0 && i < sg_size) {
304                 pg = virt_to_page(addr);
305                 offset = offset_in_page(addr);
306                 if (sg)
307                         sg_set_page(&sg[i], pg, 0, offset);
308                 remainder_of_page = PAGE_CACHE_SIZE - offset;
309                 if (size >= remainder_of_page) {
310                         if (sg)
311                                 sg[i].length = remainder_of_page;
312                         addr += remainder_of_page;
313                         size -= remainder_of_page;
314                 } else {
315                         if (sg)
316                                 sg[i].length = size;
317                         addr += size;
318                         size = 0;
319                 }
320                 i++;
321         }
322         if (size > 0)
323                 return -ENOMEM;
324         return i;
325 }
326
327 /**
328  * encrypt_scatterlist
329  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
330  * @dest_sg: Destination of encrypted data
331  * @src_sg: Data to be encrypted
332  * @size: Length of data to be encrypted
333  * @iv: iv to use during encryption
334  *
335  * Returns the number of bytes encrypted; negative value on error
336  */
337 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
338                                struct scatterlist *dest_sg,
339                                struct scatterlist *src_sg, int size,
340                                unsigned char *iv)
341 {
342         struct blkcipher_desc desc = {
343                 .tfm = crypt_stat->tfm,
344                 .info = iv,
345                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
346         };
347         int rc = 0;
348
349         BUG_ON(!crypt_stat || !crypt_stat->tfm
350                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
351         if (unlikely(ecryptfs_verbosity > 0)) {
352                 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
353                                 crypt_stat->key_size);
354                 ecryptfs_dump_hex(crypt_stat->key,
355                                   crypt_stat->key_size);
356         }
357         /* Consider doing this once, when the file is opened */
358         mutex_lock(&crypt_stat->cs_tfm_mutex);
359         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
360                 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
361                                              crypt_stat->key_size);
362                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
363         }
364         if (rc) {
365                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
366                                 rc);
367                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
368                 rc = -EINVAL;
369                 goto out;
370         }
371         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
372         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
373         mutex_unlock(&crypt_stat->cs_tfm_mutex);
374 out:
375         return rc;
376 }
377
378 /**
379  * ecryptfs_lower_offset_for_extent
380  *
381  * Convert an eCryptfs page index into a lower byte offset
382  */
383 static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
384                                              struct ecryptfs_crypt_stat *crypt_stat)
385 {
386         (*offset) = (crypt_stat->num_header_bytes_at_front
387                      + (crypt_stat->extent_size * extent_num));
388 }
389
390 /**
391  * ecryptfs_encrypt_extent
392  * @enc_extent_page: Allocated page into which to encrypt the data in
393  *                   @page
394  * @crypt_stat: crypt_stat containing cryptographic context for the
395  *              encryption operation
396  * @page: Page containing plaintext data extent to encrypt
397  * @extent_offset: Page extent offset for use in generating IV
398  *
399  * Encrypts one extent of data.
400  *
401  * Return zero on success; non-zero otherwise
402  */
403 static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
404                                    struct ecryptfs_crypt_stat *crypt_stat,
405                                    struct page *page,
406                                    unsigned long extent_offset)
407 {
408         loff_t extent_base;
409         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
410         int rc;
411
412         extent_base = (((loff_t)page->index)
413                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
414         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
415                                 (extent_base + extent_offset));
416         if (rc) {
417                 ecryptfs_printk(KERN_ERR, "Error attempting to "
418                                 "derive IV for extent [0x%.16x]; "
419                                 "rc = [%d]\n", (extent_base + extent_offset),
420                                 rc);
421                 goto out;
422         }
423         if (unlikely(ecryptfs_verbosity > 0)) {
424                 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
425                                 "with iv:\n");
426                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
427                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
428                                 "encryption:\n");
429                 ecryptfs_dump_hex((char *)
430                                   (page_address(page)
431                                    + (extent_offset * crypt_stat->extent_size)),
432                                   8);
433         }
434         rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
435                                           page, (extent_offset
436                                                  * crypt_stat->extent_size),
437                                           crypt_stat->extent_size, extent_iv);
438         if (rc < 0) {
439                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
440                        "page->index = [%ld], extent_offset = [%ld]; "
441                        "rc = [%d]\n", __func__, page->index, extent_offset,
442                        rc);
443                 goto out;
444         }
445         rc = 0;
446         if (unlikely(ecryptfs_verbosity > 0)) {
447                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
448                                 "rc = [%d]\n", (extent_base + extent_offset),
449                                 rc);
450                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
451                                 "encryption:\n");
452                 ecryptfs_dump_hex((char *)(page_address(enc_extent_page)), 8);
453         }
454 out:
455         return rc;
456 }
457
458 /**
459  * ecryptfs_encrypt_page
460  * @page: Page mapped from the eCryptfs inode for the file; contains
461  *        decrypted content that needs to be encrypted (to a temporary
462  *        page; not in place) and written out to the lower file
463  *
464  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
465  * that eCryptfs pages may straddle the lower pages -- for instance,
466  * if the file was created on a machine with an 8K page size
467  * (resulting in an 8K header), and then the file is copied onto a
468  * host with a 32K page size, then when reading page 0 of the eCryptfs
469  * file, 24K of page 0 of the lower file will be read and decrypted,
470  * and then 8K of page 1 of the lower file will be read and decrypted.
471  *
472  * Returns zero on success; negative on error
473  */
474 int ecryptfs_encrypt_page(struct page *page)
475 {
476         struct inode *ecryptfs_inode;
477         struct ecryptfs_crypt_stat *crypt_stat;
478         char *enc_extent_virt;
479         struct page *enc_extent_page = NULL;
480         loff_t extent_offset;
481         int rc = 0;
482
483         ecryptfs_inode = page->mapping->host;
484         crypt_stat =
485                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
486         if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
487                 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page,
488                                                        0, PAGE_CACHE_SIZE);
489                 if (rc)
490                         printk(KERN_ERR "%s: Error attempting to copy "
491                                "page at index [%ld]\n", __func__,
492                                page->index);
493                 goto out;
494         }
495         enc_extent_page = alloc_page(GFP_USER);
496         if (!enc_extent_page) {
497                 rc = -ENOMEM;
498                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
499                                 "encrypted extent\n");
500                 goto out;
501         }
502         enc_extent_virt = kmap(enc_extent_page);
503         for (extent_offset = 0;
504              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
505              extent_offset++) {
506                 loff_t offset;
507
508                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
509                                              extent_offset);
510                 if (rc) {
511                         printk(KERN_ERR "%s: Error encrypting extent; "
512                                "rc = [%d]\n", __func__, rc);
513                         goto out;
514                 }
515                 ecryptfs_lower_offset_for_extent(
516                         &offset, ((((loff_t)page->index)
517                                    * (PAGE_CACHE_SIZE
518                                       / crypt_stat->extent_size))
519                                   + extent_offset), crypt_stat);
520                 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
521                                           offset, crypt_stat->extent_size);
522                 if (rc) {
523                         ecryptfs_printk(KERN_ERR, "Error attempting "
524                                         "to write lower page; rc = [%d]"
525                                         "\n", rc);
526                         goto out;
527                 }
528         }
529 out:
530         if (enc_extent_page) {
531                 kunmap(enc_extent_page);
532                 __free_page(enc_extent_page);
533         }
534         return rc;
535 }
536
537 static int ecryptfs_decrypt_extent(struct page *page,
538                                    struct ecryptfs_crypt_stat *crypt_stat,
539                                    struct page *enc_extent_page,
540                                    unsigned long extent_offset)
541 {
542         loff_t extent_base;
543         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
544         int rc;
545
546         extent_base = (((loff_t)page->index)
547                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
548         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
549                                 (extent_base + extent_offset));
550         if (rc) {
551                 ecryptfs_printk(KERN_ERR, "Error attempting to "
552                                 "derive IV for extent [0x%.16x]; "
553                                 "rc = [%d]\n", (extent_base + extent_offset),
554                                 rc);
555                 goto out;
556         }
557         if (unlikely(ecryptfs_verbosity > 0)) {
558                 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
559                                 "with iv:\n");
560                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
561                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
562                                 "decryption:\n");
563                 ecryptfs_dump_hex((char *)
564                                   (page_address(enc_extent_page)
565                                    + (extent_offset * crypt_stat->extent_size)),
566                                   8);
567         }
568         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
569                                           (extent_offset
570                                            * crypt_stat->extent_size),
571                                           enc_extent_page, 0,
572                                           crypt_stat->extent_size, extent_iv);
573         if (rc < 0) {
574                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
575                        "page->index = [%ld], extent_offset = [%ld]; "
576                        "rc = [%d]\n", __func__, page->index, extent_offset,
577                        rc);
578                 goto out;
579         }
580         rc = 0;
581         if (unlikely(ecryptfs_verbosity > 0)) {
582                 ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16x]; "
583                                 "rc = [%d]\n", (extent_base + extent_offset),
584                                 rc);
585                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
586                                 "decryption:\n");
587                 ecryptfs_dump_hex((char *)(page_address(page)
588                                            + (extent_offset
589                                               * crypt_stat->extent_size)), 8);
590         }
591 out:
592         return rc;
593 }
594
595 /**
596  * ecryptfs_decrypt_page
597  * @page: Page mapped from the eCryptfs inode for the file; data read
598  *        and decrypted from the lower file will be written into this
599  *        page
600  *
601  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
602  * that eCryptfs pages may straddle the lower pages -- for instance,
603  * if the file was created on a machine with an 8K page size
604  * (resulting in an 8K header), and then the file is copied onto a
605  * host with a 32K page size, then when reading page 0 of the eCryptfs
606  * file, 24K of page 0 of the lower file will be read and decrypted,
607  * and then 8K of page 1 of the lower file will be read and decrypted.
608  *
609  * Returns zero on success; negative on error
610  */
611 int ecryptfs_decrypt_page(struct page *page)
612 {
613         struct inode *ecryptfs_inode;
614         struct ecryptfs_crypt_stat *crypt_stat;
615         char *enc_extent_virt;
616         struct page *enc_extent_page = NULL;
617         unsigned long extent_offset;
618         int rc = 0;
619
620         ecryptfs_inode = page->mapping->host;
621         crypt_stat =
622                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
623         if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
624                 rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
625                                                       PAGE_CACHE_SIZE,
626                                                       ecryptfs_inode);
627                 if (rc)
628                         printk(KERN_ERR "%s: Error attempting to copy "
629                                "page at index [%ld]\n", __func__,
630                                page->index);
631                 goto out;
632         }
633         enc_extent_page = alloc_page(GFP_USER);
634         if (!enc_extent_page) {
635                 rc = -ENOMEM;
636                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
637                                 "encrypted extent\n");
638                 goto out;
639         }
640         enc_extent_virt = kmap(enc_extent_page);
641         for (extent_offset = 0;
642              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
643              extent_offset++) {
644                 loff_t offset;
645
646                 ecryptfs_lower_offset_for_extent(
647                         &offset, ((page->index * (PAGE_CACHE_SIZE
648                                                   / crypt_stat->extent_size))
649                                   + extent_offset), crypt_stat);
650                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
651                                          crypt_stat->extent_size,
652                                          ecryptfs_inode);
653                 if (rc) {
654                         ecryptfs_printk(KERN_ERR, "Error attempting "
655                                         "to read lower page; rc = [%d]"
656                                         "\n", rc);
657                         goto out;
658                 }
659                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
660                                              extent_offset);
661                 if (rc) {
662                         printk(KERN_ERR "%s: Error encrypting extent; "
663                                "rc = [%d]\n", __func__, rc);
664                         goto out;
665                 }
666         }
667 out:
668         if (enc_extent_page) {
669                 kunmap(enc_extent_page);
670                 __free_page(enc_extent_page);
671         }
672         return rc;
673 }
674
675 /**
676  * decrypt_scatterlist
677  * @crypt_stat: Cryptographic context
678  * @dest_sg: The destination scatterlist to decrypt into
679  * @src_sg: The source scatterlist to decrypt from
680  * @size: The number of bytes to decrypt
681  * @iv: The initialization vector to use for the decryption
682  *
683  * Returns the number of bytes decrypted; negative value on error
684  */
685 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
686                                struct scatterlist *dest_sg,
687                                struct scatterlist *src_sg, int size,
688                                unsigned char *iv)
689 {
690         struct blkcipher_desc desc = {
691                 .tfm = crypt_stat->tfm,
692                 .info = iv,
693                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
694         };
695         int rc = 0;
696
697         /* Consider doing this once, when the file is opened */
698         mutex_lock(&crypt_stat->cs_tfm_mutex);
699         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
700                                      crypt_stat->key_size);
701         if (rc) {
702                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
703                                 rc);
704                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
705                 rc = -EINVAL;
706                 goto out;
707         }
708         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
709         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
710         mutex_unlock(&crypt_stat->cs_tfm_mutex);
711         if (rc) {
712                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
713                                 rc);
714                 goto out;
715         }
716         rc = size;
717 out:
718         return rc;
719 }
720
721 /**
722  * ecryptfs_encrypt_page_offset
723  * @crypt_stat: The cryptographic context
724  * @dst_page: The page to encrypt into
725  * @dst_offset: The offset in the page to encrypt into
726  * @src_page: The page to encrypt from
727  * @src_offset: The offset in the page to encrypt from
728  * @size: The number of bytes to encrypt
729  * @iv: The initialization vector to use for the encryption
730  *
731  * Returns the number of bytes encrypted
732  */
733 static int
734 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
735                              struct page *dst_page, int dst_offset,
736                              struct page *src_page, int src_offset, int size,
737                              unsigned char *iv)
738 {
739         struct scatterlist src_sg, dst_sg;
740
741         sg_init_table(&src_sg, 1);
742         sg_init_table(&dst_sg, 1);
743
744         sg_set_page(&src_sg, src_page, size, src_offset);
745         sg_set_page(&dst_sg, dst_page, size, dst_offset);
746         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
747 }
748
749 /**
750  * ecryptfs_decrypt_page_offset
751  * @crypt_stat: The cryptographic context
752  * @dst_page: The page to decrypt into
753  * @dst_offset: The offset in the page to decrypt into
754  * @src_page: The page to decrypt from
755  * @src_offset: The offset in the page to decrypt from
756  * @size: The number of bytes to decrypt
757  * @iv: The initialization vector to use for the decryption
758  *
759  * Returns the number of bytes decrypted
760  */
761 static int
762 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
763                              struct page *dst_page, int dst_offset,
764                              struct page *src_page, int src_offset, int size,
765                              unsigned char *iv)
766 {
767         struct scatterlist src_sg, dst_sg;
768
769         sg_init_table(&src_sg, 1);
770         sg_set_page(&src_sg, src_page, size, src_offset);
771
772         sg_init_table(&dst_sg, 1);
773         sg_set_page(&dst_sg, dst_page, size, dst_offset);
774
775         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
776 }
777
778 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
779
780 /**
781  * ecryptfs_init_crypt_ctx
782  * @crypt_stat: Uninitilized crypt stats structure
783  *
784  * Initialize the crypto context.
785  *
786  * TODO: Performance: Keep a cache of initialized cipher contexts;
787  * only init if needed
788  */
789 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
790 {
791         char *full_alg_name;
792         int rc = -EINVAL;
793
794         if (!crypt_stat->cipher) {
795                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
796                 goto out;
797         }
798         ecryptfs_printk(KERN_DEBUG,
799                         "Initializing cipher [%s]; strlen = [%d]; "
800                         "key_size_bits = [%d]\n",
801                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
802                         crypt_stat->key_size << 3);
803         if (crypt_stat->tfm) {
804                 rc = 0;
805                 goto out;
806         }
807         mutex_lock(&crypt_stat->cs_tfm_mutex);
808         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
809                                                     crypt_stat->cipher, "cbc");
810         if (rc)
811                 goto out_unlock;
812         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
813                                                  CRYPTO_ALG_ASYNC);
814         kfree(full_alg_name);
815         if (IS_ERR(crypt_stat->tfm)) {
816                 rc = PTR_ERR(crypt_stat->tfm);
817                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
818                                 "Error initializing cipher [%s]\n",
819                                 crypt_stat->cipher);
820                 goto out_unlock;
821         }
822         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
823         rc = 0;
824 out_unlock:
825         mutex_unlock(&crypt_stat->cs_tfm_mutex);
826 out:
827         return rc;
828 }
829
830 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
831 {
832         int extent_size_tmp;
833
834         crypt_stat->extent_mask = 0xFFFFFFFF;
835         crypt_stat->extent_shift = 0;
836         if (crypt_stat->extent_size == 0)
837                 return;
838         extent_size_tmp = crypt_stat->extent_size;
839         while ((extent_size_tmp & 0x01) == 0) {
840                 extent_size_tmp >>= 1;
841                 crypt_stat->extent_mask <<= 1;
842                 crypt_stat->extent_shift++;
843         }
844 }
845
846 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
847 {
848         /* Default values; may be overwritten as we are parsing the
849          * packets. */
850         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
851         set_extent_mask_and_shift(crypt_stat);
852         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
853         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
854                 crypt_stat->num_header_bytes_at_front = 0;
855         else {
856                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
857                         crypt_stat->num_header_bytes_at_front =
858                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
859                 else
860                         crypt_stat->num_header_bytes_at_front = PAGE_CACHE_SIZE;
861         }
862 }
863
864 /**
865  * ecryptfs_compute_root_iv
866  * @crypt_stats
867  *
868  * On error, sets the root IV to all 0's.
869  */
870 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
871 {
872         int rc = 0;
873         char dst[MD5_DIGEST_SIZE];
874
875         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
876         BUG_ON(crypt_stat->iv_bytes <= 0);
877         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
878                 rc = -EINVAL;
879                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
880                                 "cannot generate root IV\n");
881                 goto out;
882         }
883         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
884                                     crypt_stat->key_size);
885         if (rc) {
886                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
887                                 "MD5 while generating root IV\n");
888                 goto out;
889         }
890         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
891 out:
892         if (rc) {
893                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
894                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
895         }
896         return rc;
897 }
898
899 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
900 {
901         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
902         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
903         ecryptfs_compute_root_iv(crypt_stat);
904         if (unlikely(ecryptfs_verbosity > 0)) {
905                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
906                 ecryptfs_dump_hex(crypt_stat->key,
907                                   crypt_stat->key_size);
908         }
909 }
910
911 /**
912  * ecryptfs_copy_mount_wide_flags_to_inode_flags
913  * @crypt_stat: The inode's cryptographic context
914  * @mount_crypt_stat: The mount point's cryptographic context
915  *
916  * This function propagates the mount-wide flags to individual inode
917  * flags.
918  */
919 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
920         struct ecryptfs_crypt_stat *crypt_stat,
921         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
922 {
923         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
924                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
925         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
926                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
927         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
928                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
929                 if (mount_crypt_stat->flags
930                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
931                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
932                 else if (mount_crypt_stat->flags
933                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
934                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
935         }
936 }
937
938 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
939         struct ecryptfs_crypt_stat *crypt_stat,
940         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
941 {
942         struct ecryptfs_global_auth_tok *global_auth_tok;
943         int rc = 0;
944
945         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
946         list_for_each_entry(global_auth_tok,
947                             &mount_crypt_stat->global_auth_tok_list,
948                             mount_crypt_stat_list) {
949                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
950                         continue;
951                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
952                 if (rc) {
953                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
954                         mutex_unlock(
955                                 &mount_crypt_stat->global_auth_tok_list_mutex);
956                         goto out;
957                 }
958         }
959         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
960 out:
961         return rc;
962 }
963
964 /**
965  * ecryptfs_set_default_crypt_stat_vals
966  * @crypt_stat: The inode's cryptographic context
967  * @mount_crypt_stat: The mount point's cryptographic context
968  *
969  * Default values in the event that policy does not override them.
970  */
971 static void ecryptfs_set_default_crypt_stat_vals(
972         struct ecryptfs_crypt_stat *crypt_stat,
973         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
974 {
975         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
976                                                       mount_crypt_stat);
977         ecryptfs_set_default_sizes(crypt_stat);
978         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
979         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
980         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
981         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
982         crypt_stat->mount_crypt_stat = mount_crypt_stat;
983 }
984
985 /**
986  * ecryptfs_new_file_context
987  * @ecryptfs_dentry: The eCryptfs dentry
988  *
989  * If the crypto context for the file has not yet been established,
990  * this is where we do that.  Establishing a new crypto context
991  * involves the following decisions:
992  *  - What cipher to use?
993  *  - What set of authentication tokens to use?
994  * Here we just worry about getting enough information into the
995  * authentication tokens so that we know that they are available.
996  * We associate the available authentication tokens with the new file
997  * via the set of signatures in the crypt_stat struct.  Later, when
998  * the headers are actually written out, we may again defer to
999  * userspace to perform the encryption of the session key; for the
1000  * foreseeable future, this will be the case with public key packets.
1001  *
1002  * Returns zero on success; non-zero otherwise
1003  */
1004 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
1005 {
1006         struct ecryptfs_crypt_stat *crypt_stat =
1007             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1008         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1009             &ecryptfs_superblock_to_private(
1010                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
1011         int cipher_name_len;
1012         int rc = 0;
1013
1014         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
1015         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1016         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1017                                                       mount_crypt_stat);
1018         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1019                                                          mount_crypt_stat);
1020         if (rc) {
1021                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1022                        "to the inode key sigs; rc = [%d]\n", rc);
1023                 goto out;
1024         }
1025         cipher_name_len =
1026                 strlen(mount_crypt_stat->global_default_cipher_name);
1027         memcpy(crypt_stat->cipher,
1028                mount_crypt_stat->global_default_cipher_name,
1029                cipher_name_len);
1030         crypt_stat->cipher[cipher_name_len] = '\0';
1031         crypt_stat->key_size =
1032                 mount_crypt_stat->global_default_cipher_key_size;
1033         ecryptfs_generate_new_key(crypt_stat);
1034         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1035         if (rc)
1036                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1037                                 "context for cipher [%s]: rc = [%d]\n",
1038                                 crypt_stat->cipher, rc);
1039 out:
1040         return rc;
1041 }
1042
1043 /**
1044  * contains_ecryptfs_marker - check for the ecryptfs marker
1045  * @data: The data block in which to check
1046  *
1047  * Returns one if marker found; zero if not found
1048  */
1049 static int contains_ecryptfs_marker(char *data)
1050 {
1051         u32 m_1, m_2;
1052
1053         m_1 = get_unaligned_be32(data);
1054         m_2 = get_unaligned_be32(data + 4);
1055         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1056                 return 1;
1057         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1058                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1059                         MAGIC_ECRYPTFS_MARKER);
1060         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1061                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1062         return 0;
1063 }
1064
1065 struct ecryptfs_flag_map_elem {
1066         u32 file_flag;
1067         u32 local_flag;
1068 };
1069
1070 /* Add support for additional flags by adding elements here. */
1071 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1072         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1073         {0x00000002, ECRYPTFS_ENCRYPTED},
1074         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1075         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1076 };
1077
1078 /**
1079  * ecryptfs_process_flags
1080  * @crypt_stat: The cryptographic context
1081  * @page_virt: Source data to be parsed
1082  * @bytes_read: Updated with the number of bytes read
1083  *
1084  * Returns zero on success; non-zero if the flag set is invalid
1085  */
1086 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1087                                   char *page_virt, int *bytes_read)
1088 {
1089         int rc = 0;
1090         int i;
1091         u32 flags;
1092
1093         flags = get_unaligned_be32(page_virt);
1094         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1095                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1096                 if (flags & ecryptfs_flag_map[i].file_flag) {
1097                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1098                 } else
1099                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1100         /* Version is in top 8 bits of the 32-bit flag vector */
1101         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1102         (*bytes_read) = 4;
1103         return rc;
1104 }
1105
1106 /**
1107  * write_ecryptfs_marker
1108  * @page_virt: The pointer to in a page to begin writing the marker
1109  * @written: Number of bytes written
1110  *
1111  * Marker = 0x3c81b7f5
1112  */
1113 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1114 {
1115         u32 m_1, m_2;
1116
1117         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1118         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1119         put_unaligned_be32(m_1, page_virt);
1120         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1121         put_unaligned_be32(m_2, page_virt);
1122         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1123 }
1124
1125 static void
1126 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1127                      size_t *written)
1128 {
1129         u32 flags = 0;
1130         int i;
1131
1132         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1133                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1134                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1135                         flags |= ecryptfs_flag_map[i].file_flag;
1136         /* Version is in top 8 bits of the 32-bit flag vector */
1137         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1138         put_unaligned_be32(flags, page_virt);
1139         (*written) = 4;
1140 }
1141
1142 struct ecryptfs_cipher_code_str_map_elem {
1143         char cipher_str[16];
1144         u8 cipher_code;
1145 };
1146
1147 /* Add support for additional ciphers by adding elements here. The
1148  * cipher_code is whatever OpenPGP applicatoins use to identify the
1149  * ciphers. List in order of probability. */
1150 static struct ecryptfs_cipher_code_str_map_elem
1151 ecryptfs_cipher_code_str_map[] = {
1152         {"aes",RFC2440_CIPHER_AES_128 },
1153         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1154         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1155         {"cast5", RFC2440_CIPHER_CAST_5},
1156         {"twofish", RFC2440_CIPHER_TWOFISH},
1157         {"cast6", RFC2440_CIPHER_CAST_6},
1158         {"aes", RFC2440_CIPHER_AES_192},
1159         {"aes", RFC2440_CIPHER_AES_256}
1160 };
1161
1162 /**
1163  * ecryptfs_code_for_cipher_string
1164  * @cipher_name: The string alias for the cipher
1165  * @key_bytes: Length of key in bytes; used for AES code selection
1166  *
1167  * Returns zero on no match, or the cipher code on match
1168  */
1169 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1170 {
1171         int i;
1172         u8 code = 0;
1173         struct ecryptfs_cipher_code_str_map_elem *map =
1174                 ecryptfs_cipher_code_str_map;
1175
1176         if (strcmp(cipher_name, "aes") == 0) {
1177                 switch (key_bytes) {
1178                 case 16:
1179                         code = RFC2440_CIPHER_AES_128;
1180                         break;
1181                 case 24:
1182                         code = RFC2440_CIPHER_AES_192;
1183                         break;
1184                 case 32:
1185                         code = RFC2440_CIPHER_AES_256;
1186                 }
1187         } else {
1188                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1189                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1190                                 code = map[i].cipher_code;
1191                                 break;
1192                         }
1193         }
1194         return code;
1195 }
1196
1197 /**
1198  * ecryptfs_cipher_code_to_string
1199  * @str: Destination to write out the cipher name
1200  * @cipher_code: The code to convert to cipher name string
1201  *
1202  * Returns zero on success
1203  */
1204 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1205 {
1206         int rc = 0;
1207         int i;
1208
1209         str[0] = '\0';
1210         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1211                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1212                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1213         if (str[0] == '\0') {
1214                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1215                                 "[%d]\n", cipher_code);
1216                 rc = -EINVAL;
1217         }
1218         return rc;
1219 }
1220
1221 int ecryptfs_read_and_validate_header_region(char *data,
1222                                              struct inode *ecryptfs_inode)
1223 {
1224         struct ecryptfs_crypt_stat *crypt_stat =
1225                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
1226         int rc;
1227
1228         if (crypt_stat->extent_size == 0)
1229                 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
1230         rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
1231                                  ecryptfs_inode);
1232         if (rc) {
1233                 printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
1234                        __func__, rc);
1235                 goto out;
1236         }
1237         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) {
1238                 rc = -EINVAL;
1239         }
1240 out:
1241         return rc;
1242 }
1243
1244 void
1245 ecryptfs_write_header_metadata(char *virt,
1246                                struct ecryptfs_crypt_stat *crypt_stat,
1247                                size_t *written)
1248 {
1249         u32 header_extent_size;
1250         u16 num_header_extents_at_front;
1251
1252         header_extent_size = (u32)crypt_stat->extent_size;
1253         num_header_extents_at_front =
1254                 (u16)(crypt_stat->num_header_bytes_at_front
1255                       / crypt_stat->extent_size);
1256         put_unaligned_be32(header_extent_size, virt);
1257         virt += 4;
1258         put_unaligned_be16(num_header_extents_at_front, virt);
1259         (*written) = 6;
1260 }
1261
1262 struct kmem_cache *ecryptfs_header_cache_1;
1263 struct kmem_cache *ecryptfs_header_cache_2;
1264
1265 /**
1266  * ecryptfs_write_headers_virt
1267  * @page_virt: The virtual address to write the headers to
1268  * @max: The size of memory allocated at page_virt
1269  * @size: Set to the number of bytes written by this function
1270  * @crypt_stat: The cryptographic context
1271  * @ecryptfs_dentry: The eCryptfs dentry
1272  *
1273  * Format version: 1
1274  *
1275  *   Header Extent:
1276  *     Octets 0-7:        Unencrypted file size (big-endian)
1277  *     Octets 8-15:       eCryptfs special marker
1278  *     Octets 16-19:      Flags
1279  *      Octet 16:         File format version number (between 0 and 255)
1280  *      Octets 17-18:     Reserved
1281  *      Octet 19:         Bit 1 (lsb): Reserved
1282  *                        Bit 2: Encrypted?
1283  *                        Bits 3-8: Reserved
1284  *     Octets 20-23:      Header extent size (big-endian)
1285  *     Octets 24-25:      Number of header extents at front of file
1286  *                        (big-endian)
1287  *     Octet  26:         Begin RFC 2440 authentication token packet set
1288  *   Data Extent 0:
1289  *     Lower data (CBC encrypted)
1290  *   Data Extent 1:
1291  *     Lower data (CBC encrypted)
1292  *   ...
1293  *
1294  * Returns zero on success
1295  */
1296 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1297                                        size_t *size,
1298                                        struct ecryptfs_crypt_stat *crypt_stat,
1299                                        struct dentry *ecryptfs_dentry)
1300 {
1301         int rc;
1302         size_t written;
1303         size_t offset;
1304
1305         offset = ECRYPTFS_FILE_SIZE_BYTES;
1306         write_ecryptfs_marker((page_virt + offset), &written);
1307         offset += written;
1308         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1309         offset += written;
1310         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1311                                        &written);
1312         offset += written;
1313         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1314                                               ecryptfs_dentry, &written,
1315                                               max - offset);
1316         if (rc)
1317                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1318                                 "set; rc = [%d]\n", rc);
1319         if (size) {
1320                 offset += written;
1321                 *size = offset;
1322         }
1323         return rc;
1324 }
1325
1326 static int
1327 ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
1328                                     struct dentry *ecryptfs_dentry,
1329                                     char *virt)
1330 {
1331         int rc;
1332
1333         rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
1334                                   0, crypt_stat->num_header_bytes_at_front);
1335         if (rc)
1336                 printk(KERN_ERR "%s: Error attempting to write header "
1337                        "information to lower file; rc = [%d]\n", __func__,
1338                        rc);
1339         return rc;
1340 }
1341
1342 static int
1343 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1344                                  struct ecryptfs_crypt_stat *crypt_stat,
1345                                  char *page_virt, size_t size)
1346 {
1347         int rc;
1348
1349         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1350                                size, 0);
1351         return rc;
1352 }
1353
1354 /**
1355  * ecryptfs_write_metadata
1356  * @ecryptfs_dentry: The eCryptfs dentry
1357  *
1358  * Write the file headers out.  This will likely involve a userspace
1359  * callout, in which the session key is encrypted with one or more
1360  * public keys and/or the passphrase necessary to do the encryption is
1361  * retrieved via a prompt.  Exactly what happens at this point should
1362  * be policy-dependent.
1363  *
1364  * Returns zero on success; non-zero on error
1365  */
1366 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
1367 {
1368         struct ecryptfs_crypt_stat *crypt_stat =
1369                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1370         char *virt;
1371         size_t size = 0;
1372         int rc = 0;
1373
1374         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1375                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1376                         printk(KERN_ERR "Key is invalid; bailing out\n");
1377                         rc = -EINVAL;
1378                         goto out;
1379                 }
1380         } else {
1381                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1382                        __func__);
1383                 rc = -EINVAL;
1384                 goto out;
1385         }
1386         /* Released in this function */
1387         virt = (char *)get_zeroed_page(GFP_KERNEL);
1388         if (!virt) {
1389                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1390                 rc = -ENOMEM;
1391                 goto out;
1392         }
1393         rc = ecryptfs_write_headers_virt(virt, PAGE_CACHE_SIZE, &size,
1394                                          crypt_stat, ecryptfs_dentry);
1395         if (unlikely(rc)) {
1396                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1397                        __func__, rc);
1398                 goto out_free;
1399         }
1400         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1401                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
1402                                                       crypt_stat, virt, size);
1403         else
1404                 rc = ecryptfs_write_metadata_to_contents(crypt_stat,
1405                                                          ecryptfs_dentry, virt);
1406         if (rc) {
1407                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1408                        "rc = [%d]\n", __func__, rc);
1409                 goto out_free;
1410         }
1411 out_free:
1412         free_page((unsigned long)virt);
1413 out:
1414         return rc;
1415 }
1416
1417 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1418 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1419 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1420                                  char *virt, int *bytes_read,
1421                                  int validate_header_size)
1422 {
1423         int rc = 0;
1424         u32 header_extent_size;
1425         u16 num_header_extents_at_front;
1426
1427         header_extent_size = get_unaligned_be32(virt);
1428         virt += sizeof(__be32);
1429         num_header_extents_at_front = get_unaligned_be16(virt);
1430         crypt_stat->num_header_bytes_at_front =
1431                 (((size_t)num_header_extents_at_front
1432                   * (size_t)header_extent_size));
1433         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1434         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1435             && (crypt_stat->num_header_bytes_at_front
1436                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1437                 rc = -EINVAL;
1438                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1439                        crypt_stat->num_header_bytes_at_front);
1440         }
1441         return rc;
1442 }
1443
1444 /**
1445  * set_default_header_data
1446  * @crypt_stat: The cryptographic context
1447  *
1448  * For version 0 file format; this function is only for backwards
1449  * compatibility for files created with the prior versions of
1450  * eCryptfs.
1451  */
1452 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1453 {
1454         crypt_stat->num_header_bytes_at_front =
1455                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1456 }
1457
1458 /**
1459  * ecryptfs_read_headers_virt
1460  * @page_virt: The virtual address into which to read the headers
1461  * @crypt_stat: The cryptographic context
1462  * @ecryptfs_dentry: The eCryptfs dentry
1463  * @validate_header_size: Whether to validate the header size while reading
1464  *
1465  * Read/parse the header data. The header format is detailed in the
1466  * comment block for the ecryptfs_write_headers_virt() function.
1467  *
1468  * Returns zero on success
1469  */
1470 static int ecryptfs_read_headers_virt(char *page_virt,
1471                                       struct ecryptfs_crypt_stat *crypt_stat,
1472                                       struct dentry *ecryptfs_dentry,
1473                                       int validate_header_size)
1474 {
1475         int rc = 0;
1476         int offset;
1477         int bytes_read;
1478
1479         ecryptfs_set_default_sizes(crypt_stat);
1480         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1481                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1482         offset = ECRYPTFS_FILE_SIZE_BYTES;
1483         rc = contains_ecryptfs_marker(page_virt + offset);
1484         if (rc == 0) {
1485                 rc = -EINVAL;
1486                 goto out;
1487         }
1488         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1489         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1490                                     &bytes_read);
1491         if (rc) {
1492                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1493                 goto out;
1494         }
1495         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1496                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1497                                 "file version [%d] is supported by this "
1498                                 "version of eCryptfs\n",
1499                                 crypt_stat->file_version,
1500                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1501                 rc = -EINVAL;
1502                 goto out;
1503         }
1504         offset += bytes_read;
1505         if (crypt_stat->file_version >= 1) {
1506                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1507                                            &bytes_read, validate_header_size);
1508                 if (rc) {
1509                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1510                                         "metadata; rc = [%d]\n", rc);
1511                 }
1512                 offset += bytes_read;
1513         } else
1514                 set_default_header_data(crypt_stat);
1515         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1516                                        ecryptfs_dentry);
1517 out:
1518         return rc;
1519 }
1520
1521 /**
1522  * ecryptfs_read_xattr_region
1523  * @page_virt: The vitual address into which to read the xattr data
1524  * @ecryptfs_inode: The eCryptfs inode
1525  *
1526  * Attempts to read the crypto metadata from the extended attribute
1527  * region of the lower file.
1528  *
1529  * Returns zero on success; non-zero on error
1530  */
1531 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1532 {
1533         struct dentry *lower_dentry =
1534                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1535         ssize_t size;
1536         int rc = 0;
1537
1538         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1539                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1540         if (size < 0) {
1541                 if (unlikely(ecryptfs_verbosity > 0))
1542                         printk(KERN_INFO "Error attempting to read the [%s] "
1543                                "xattr from the lower file; return value = "
1544                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1545                 rc = -EINVAL;
1546                 goto out;
1547         }
1548 out:
1549         return rc;
1550 }
1551
1552 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1553                                             struct dentry *ecryptfs_dentry)
1554 {
1555         int rc;
1556
1557         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
1558         if (rc)
1559                 goto out;
1560         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1561                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1562                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1563                 rc = -EINVAL;
1564         }
1565 out:
1566         return rc;
1567 }
1568
1569 /**
1570  * ecryptfs_read_metadata
1571  *
1572  * Common entry point for reading file metadata. From here, we could
1573  * retrieve the header information from the header region of the file,
1574  * the xattr region of the file, or some other repostory that is
1575  * stored separately from the file itself. The current implementation
1576  * supports retrieving the metadata information from the file contents
1577  * and from the xattr region.
1578  *
1579  * Returns zero if valid headers found and parsed; non-zero otherwise
1580  */
1581 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1582 {
1583         int rc = 0;
1584         char *page_virt = NULL;
1585         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1586         struct ecryptfs_crypt_stat *crypt_stat =
1587             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1588         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1589                 &ecryptfs_superblock_to_private(
1590                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1591
1592         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1593                                                       mount_crypt_stat);
1594         /* Read the first page from the underlying file */
1595         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1596         if (!page_virt) {
1597                 rc = -ENOMEM;
1598                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1599                        __func__);
1600                 goto out;
1601         }
1602         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1603                                  ecryptfs_inode);
1604         if (!rc)
1605                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1606                                                 ecryptfs_dentry,
1607                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1608         if (rc) {
1609                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1610                 if (rc) {
1611                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1612                                "file header region or xattr region\n");
1613                         rc = -EINVAL;
1614                         goto out;
1615                 }
1616                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1617                                                 ecryptfs_dentry,
1618                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1619                 if (rc) {
1620                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1621                                "file xattr region either\n");
1622                         rc = -EINVAL;
1623                 }
1624                 if (crypt_stat->mount_crypt_stat->flags
1625                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1626                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1627                 } else {
1628                         printk(KERN_WARNING "Attempt to access file with "
1629                                "crypto metadata only in the extended attribute "
1630                                "region, but eCryptfs was mounted without "
1631                                "xattr support enabled. eCryptfs will not treat "
1632                                "this like an encrypted file.\n");
1633                         rc = -EINVAL;
1634                 }
1635         }
1636 out:
1637         if (page_virt) {
1638                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1639                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1640         }
1641         return rc;
1642 }
1643
1644 /**
1645  * ecryptfs_encrypt_filename - encrypt filename
1646  *
1647  * CBC-encrypts the filename. We do not want to encrypt the same
1648  * filename with the same key and IV, which may happen with hard
1649  * links, so we prepend random bits to each filename.
1650  *
1651  * Returns zero on success; non-zero otherwise
1652  */
1653 static int
1654 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1655                           struct ecryptfs_crypt_stat *crypt_stat,
1656                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1657 {
1658         int rc = 0;
1659
1660         filename->encrypted_filename = NULL;
1661         filename->encrypted_filename_size = 0;
1662         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1663             || (mount_crypt_stat && (mount_crypt_stat->flags
1664                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1665                 size_t packet_size;
1666                 size_t remaining_bytes;
1667
1668                 rc = ecryptfs_write_tag_70_packet(
1669                         NULL, NULL,
1670                         &filename->encrypted_filename_size,
1671                         mount_crypt_stat, NULL,
1672                         filename->filename_size);
1673                 if (rc) {
1674                         printk(KERN_ERR "%s: Error attempting to get packet "
1675                                "size for tag 72; rc = [%d]\n", __func__,
1676                                rc);
1677                         filename->encrypted_filename_size = 0;
1678                         goto out;
1679                 }
1680                 filename->encrypted_filename =
1681                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1682                 if (!filename->encrypted_filename) {
1683                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1684                                "to kmalloc [%zd] bytes\n", __func__,
1685                                filename->encrypted_filename_size);
1686                         rc = -ENOMEM;
1687                         goto out;
1688                 }
1689                 remaining_bytes = filename->encrypted_filename_size;
1690                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1691                                                   &remaining_bytes,
1692                                                   &packet_size,
1693                                                   mount_crypt_stat,
1694                                                   filename->filename,
1695                                                   filename->filename_size);
1696                 if (rc) {
1697                         printk(KERN_ERR "%s: Error attempting to generate "
1698                                "tag 70 packet; rc = [%d]\n", __func__,
1699                                rc);
1700                         kfree(filename->encrypted_filename);
1701                         filename->encrypted_filename = NULL;
1702                         filename->encrypted_filename_size = 0;
1703                         goto out;
1704                 }
1705                 filename->encrypted_filename_size = packet_size;
1706         } else {
1707                 printk(KERN_ERR "%s: No support for requested filename "
1708                        "encryption method in this release\n", __func__);
1709                 rc = -ENOTSUPP;
1710                 goto out;
1711         }
1712 out:
1713         return rc;
1714 }
1715
1716 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1717                                   const char *name, size_t name_size)
1718 {
1719         int rc = 0;
1720
1721         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1722         if (!(*copied_name)) {
1723                 rc = -ENOMEM;
1724                 goto out;
1725         }
1726         memcpy((void *)(*copied_name), (void *)name, name_size);
1727         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1728                                                  * in printing out the
1729                                                  * string in debug
1730                                                  * messages */
1731         (*copied_name_size) = name_size;
1732 out:
1733         return rc;
1734 }
1735
1736 /**
1737  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1738  * @key_tfm: Crypto context for key material, set by this function
1739  * @cipher_name: Name of the cipher
1740  * @key_size: Size of the key in bytes
1741  *
1742  * Returns zero on success. Any crypto_tfm structs allocated here
1743  * should be released by other functions, such as on a superblock put
1744  * event, regardless of whether this function succeeds for fails.
1745  */
1746 static int
1747 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1748                             char *cipher_name, size_t *key_size)
1749 {
1750         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1751         char *full_alg_name;
1752         int rc;
1753
1754         *key_tfm = NULL;
1755         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1756                 rc = -EINVAL;
1757                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1758                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1759                 goto out;
1760         }
1761         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1762                                                     "ecb");
1763         if (rc)
1764                 goto out;
1765         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1766         kfree(full_alg_name);
1767         if (IS_ERR(*key_tfm)) {
1768                 rc = PTR_ERR(*key_tfm);
1769                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1770                        "[%s]; rc = [%d]\n", cipher_name, rc);
1771                 goto out;
1772         }
1773         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1774         if (*key_size == 0) {
1775                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1776
1777                 *key_size = alg->max_keysize;
1778         }
1779         get_random_bytes(dummy_key, *key_size);
1780         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1781         if (rc) {
1782                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1783                        "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
1784                 rc = -EINVAL;
1785                 goto out;
1786         }
1787 out:
1788         return rc;
1789 }
1790
1791 struct kmem_cache *ecryptfs_key_tfm_cache;
1792 static struct list_head key_tfm_list;
1793 struct mutex key_tfm_list_mutex;
1794
1795 int ecryptfs_init_crypto(void)
1796 {
1797         mutex_init(&key_tfm_list_mutex);
1798         INIT_LIST_HEAD(&key_tfm_list);
1799         return 0;
1800 }
1801
1802 /**
1803  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1804  *
1805  * Called only at module unload time
1806  */
1807 int ecryptfs_destroy_crypto(void)
1808 {
1809         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1810
1811         mutex_lock(&key_tfm_list_mutex);
1812         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1813                                  key_tfm_list) {
1814                 list_del(&key_tfm->key_tfm_list);
1815                 if (key_tfm->key_tfm)
1816                         crypto_free_blkcipher(key_tfm->key_tfm);
1817                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1818         }
1819         mutex_unlock(&key_tfm_list_mutex);
1820         return 0;
1821 }
1822
1823 int
1824 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1825                          size_t key_size)
1826 {
1827         struct ecryptfs_key_tfm *tmp_tfm;
1828         int rc = 0;
1829
1830         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1831
1832         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1833         if (key_tfm != NULL)
1834                 (*key_tfm) = tmp_tfm;
1835         if (!tmp_tfm) {
1836                 rc = -ENOMEM;
1837                 printk(KERN_ERR "Error attempting to allocate from "
1838                        "ecryptfs_key_tfm_cache\n");
1839                 goto out;
1840         }
1841         mutex_init(&tmp_tfm->key_tfm_mutex);
1842         strncpy(tmp_tfm->cipher_name, cipher_name,
1843                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1844         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1845         tmp_tfm->key_size = key_size;
1846         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1847                                          tmp_tfm->cipher_name,
1848                                          &tmp_tfm->key_size);
1849         if (rc) {
1850                 printk(KERN_ERR "Error attempting to initialize key TFM "
1851                        "cipher with name = [%s]; rc = [%d]\n",
1852                        tmp_tfm->cipher_name, rc);
1853                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1854                 if (key_tfm != NULL)
1855                         (*key_tfm) = NULL;
1856                 goto out;
1857         }
1858         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1859 out:
1860         return rc;
1861 }
1862
1863 /**
1864  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1865  * @cipher_name: the name of the cipher to search for
1866  * @key_tfm: set to corresponding tfm if found
1867  *
1868  * Searches for cached key_tfm matching @cipher_name
1869  * Must be called with &key_tfm_list_mutex held
1870  * Returns 1 if found, with @key_tfm set
1871  * Returns 0 if not found, with @key_tfm set to NULL
1872  */
1873 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1874 {
1875         struct ecryptfs_key_tfm *tmp_key_tfm;
1876
1877         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1878
1879         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1880                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1881                         if (key_tfm)
1882                                 (*key_tfm) = tmp_key_tfm;
1883                         return 1;
1884                 }
1885         }
1886         if (key_tfm)
1887                 (*key_tfm) = NULL;
1888         return 0;
1889 }
1890
1891 /**
1892  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1893  *
1894  * @tfm: set to cached tfm found, or new tfm created
1895  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1896  * @cipher_name: the name of the cipher to search for and/or add
1897  *
1898  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1899  * Searches for cached item first, and creates new if not found.
1900  * Returns 0 on success, non-zero if adding new cipher failed
1901  */
1902 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1903                                                struct mutex **tfm_mutex,
1904                                                char *cipher_name)
1905 {
1906         struct ecryptfs_key_tfm *key_tfm;
1907         int rc = 0;
1908
1909         (*tfm) = NULL;
1910         (*tfm_mutex) = NULL;
1911
1912         mutex_lock(&key_tfm_list_mutex);
1913         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1914                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1915                 if (rc) {
1916                         printk(KERN_ERR "Error adding new key_tfm to list; "
1917                                         "rc = [%d]\n", rc);
1918                         goto out;
1919                 }
1920         }
1921         (*tfm) = key_tfm->key_tfm;
1922         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1923 out:
1924         mutex_unlock(&key_tfm_list_mutex);
1925         return rc;
1926 }
1927
1928 /* 64 characters forming a 6-bit target field */
1929 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1930                                                  "EFGHIJKLMNOPQRST"
1931                                                  "UVWXYZabcdefghij"
1932                                                  "klmnopqrstuvwxyz");
1933
1934 /* We could either offset on every reverse map or just pad some 0x00's
1935  * at the front here */
1936 static const unsigned char filename_rev_map[] = {
1937         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1938         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1939         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1940         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1941         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1942         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1943         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1944         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1945         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1946         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1947         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1948         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1949         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1950         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1951         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1952         0x3D, 0x3E, 0x3F
1953 };
1954
1955 /**
1956  * ecryptfs_encode_for_filename
1957  * @dst: Destination location for encoded filename
1958  * @dst_size: Size of the encoded filename in bytes
1959  * @src: Source location for the filename to encode
1960  * @src_size: Size of the source in bytes
1961  */
1962 void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1963                                   unsigned char *src, size_t src_size)
1964 {
1965         size_t num_blocks;
1966         size_t block_num = 0;
1967         size_t dst_offset = 0;
1968         unsigned char last_block[3];
1969
1970         if (src_size == 0) {
1971                 (*dst_size) = 0;
1972                 goto out;
1973         }
1974         num_blocks = (src_size / 3);
1975         if ((src_size % 3) == 0) {
1976                 memcpy(last_block, (&src[src_size - 3]), 3);
1977         } else {
1978                 num_blocks++;
1979                 last_block[2] = 0x00;
1980                 switch (src_size % 3) {
1981                 case 1:
1982                         last_block[0] = src[src_size - 1];
1983                         last_block[1] = 0x00;
1984                         break;
1985                 case 2:
1986                         last_block[0] = src[src_size - 2];
1987                         last_block[1] = src[src_size - 1];
1988                 }
1989         }
1990         (*dst_size) = (num_blocks * 4);
1991         if (!dst)
1992                 goto out;
1993         while (block_num < num_blocks) {
1994                 unsigned char *src_block;
1995                 unsigned char dst_block[4];
1996
1997                 if (block_num == (num_blocks - 1))
1998                         src_block = last_block;
1999                 else
2000                         src_block = &src[block_num * 3];
2001                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
2002                 dst_block[1] = (((src_block[0] << 4) & 0x30)
2003                                 | ((src_block[1] >> 4) & 0x0F));
2004                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
2005                                 | ((src_block[2] >> 6) & 0x03));
2006                 dst_block[3] = (src_block[2] & 0x3F);
2007                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
2008                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
2009                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
2010                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
2011                 block_num++;
2012         }
2013 out:
2014         return;
2015 }
2016
2017 /**
2018  * ecryptfs_decode_from_filename
2019  * @dst: If NULL, this function only sets @dst_size and returns. If
2020  *       non-NULL, this function decodes the encoded octets in @src
2021  *       into the memory that @dst points to.
2022  * @dst_size: Set to the size of the decoded string.
2023  * @src: The encoded set of octets to decode.
2024  * @src_size: The size of the encoded set of octets to decode.
2025  */
2026 static void
2027 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2028                               const unsigned char *src, size_t src_size)
2029 {
2030         u8 current_bit_offset = 0;
2031         size_t src_byte_offset = 0;
2032         size_t dst_byte_offset = 0;
2033
2034         if (dst == NULL) {
2035                 /* Not exact; conservatively long. Every block of 4
2036                  * encoded characters decodes into a block of 3
2037                  * decoded characters. This segment of code provides
2038                  * the caller with the maximum amount of allocated
2039                  * space that @dst will need to point to in a
2040                  * subsequent call. */
2041                 (*dst_size) = (((src_size + 1) * 3) / 4);
2042                 goto out;
2043         }
2044         while (src_byte_offset < src_size) {
2045                 unsigned char src_byte =
2046                                 filename_rev_map[(int)src[src_byte_offset]];
2047
2048                 switch (current_bit_offset) {
2049                 case 0:
2050                         dst[dst_byte_offset] = (src_byte << 2);
2051                         current_bit_offset = 6;
2052                         break;
2053                 case 6:
2054                         dst[dst_byte_offset++] |= (src_byte >> 4);
2055                         dst[dst_byte_offset] = ((src_byte & 0xF)
2056                                                  << 4);
2057                         current_bit_offset = 4;
2058                         break;
2059                 case 4:
2060                         dst[dst_byte_offset++] |= (src_byte >> 2);
2061                         dst[dst_byte_offset] = (src_byte << 6);
2062                         current_bit_offset = 2;
2063                         break;
2064                 case 2:
2065                         dst[dst_byte_offset++] |= (src_byte);
2066                         dst[dst_byte_offset] = 0;
2067                         current_bit_offset = 0;
2068                         break;
2069                 }
2070                 src_byte_offset++;
2071         }
2072         (*dst_size) = dst_byte_offset;
2073 out:
2074         return;
2075 }
2076
2077 /**
2078  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2079  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2080  * @name: The plaintext name
2081  * @length: The length of the plaintext
2082  * @encoded_name: The encypted name
2083  *
2084  * Encrypts and encodes a filename into something that constitutes a
2085  * valid filename for a filesystem, with printable characters.
2086  *
2087  * We assume that we have a properly initialized crypto context,
2088  * pointed to by crypt_stat->tfm.
2089  *
2090  * Returns zero on success; non-zero on otherwise
2091  */
2092 int ecryptfs_encrypt_and_encode_filename(
2093         char **encoded_name,
2094         size_t *encoded_name_size,
2095         struct ecryptfs_crypt_stat *crypt_stat,
2096         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2097         const char *name, size_t name_size)
2098 {
2099         size_t encoded_name_no_prefix_size;
2100         int rc = 0;
2101
2102         (*encoded_name) = NULL;
2103         (*encoded_name_size) = 0;
2104         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2105             || (mount_crypt_stat && (mount_crypt_stat->flags
2106                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2107                 struct ecryptfs_filename *filename;
2108
2109                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2110                 if (!filename) {
2111                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2112                                "to kzalloc [%zd] bytes\n", __func__,
2113                                sizeof(*filename));
2114                         rc = -ENOMEM;
2115                         goto out;
2116                 }
2117                 filename->filename = (char *)name;
2118                 filename->filename_size = name_size;
2119                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2120                                                mount_crypt_stat);
2121                 if (rc) {
2122                         printk(KERN_ERR "%s: Error attempting to encrypt "
2123                                "filename; rc = [%d]\n", __func__, rc);
2124                         kfree(filename);
2125                         goto out;
2126                 }
2127                 ecryptfs_encode_for_filename(
2128                         NULL, &encoded_name_no_prefix_size,
2129                         filename->encrypted_filename,
2130                         filename->encrypted_filename_size);
2131                 if ((crypt_stat && (crypt_stat->flags
2132                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2133                     || (mount_crypt_stat
2134                         && (mount_crypt_stat->flags
2135                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2136                         (*encoded_name_size) =
2137                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2138                                  + encoded_name_no_prefix_size);
2139                 else
2140                         (*encoded_name_size) =
2141                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2142                                  + encoded_name_no_prefix_size);
2143                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2144                 if (!(*encoded_name)) {
2145                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2146                                "to kzalloc [%zd] bytes\n", __func__,
2147                                (*encoded_name_size));
2148                         rc = -ENOMEM;
2149                         kfree(filename->encrypted_filename);
2150                         kfree(filename);
2151                         goto out;
2152                 }
2153                 if ((crypt_stat && (crypt_stat->flags
2154                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2155                     || (mount_crypt_stat
2156                         && (mount_crypt_stat->flags
2157                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2158                         memcpy((*encoded_name),
2159                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2160                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2161                         ecryptfs_encode_for_filename(
2162                             ((*encoded_name)
2163                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2164                             &encoded_name_no_prefix_size,
2165                             filename->encrypted_filename,
2166                             filename->encrypted_filename_size);
2167                         (*encoded_name_size) =
2168                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2169                                  + encoded_name_no_prefix_size);
2170                         (*encoded_name)[(*encoded_name_size)] = '\0';
2171                         (*encoded_name_size)++;
2172                 } else {
2173                         rc = -ENOTSUPP;
2174                 }
2175                 if (rc) {
2176                         printk(KERN_ERR "%s: Error attempting to encode "
2177                                "encrypted filename; rc = [%d]\n", __func__,
2178                                rc);
2179                         kfree((*encoded_name));
2180                         (*encoded_name) = NULL;
2181                         (*encoded_name_size) = 0;
2182                 }
2183                 kfree(filename->encrypted_filename);
2184                 kfree(filename);
2185         } else {
2186                 rc = ecryptfs_copy_filename(encoded_name,
2187                                             encoded_name_size,
2188                                             name, name_size);
2189         }
2190 out:
2191         return rc;
2192 }
2193
2194 /**
2195  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2196  * @plaintext_name: The plaintext name
2197  * @plaintext_name_size: The plaintext name size
2198  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2199  * @name: The filename in cipher text
2200  * @name_size: The cipher text name size
2201  *
2202  * Decrypts and decodes the filename.
2203  *
2204  * Returns zero on error; non-zero otherwise
2205  */
2206 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2207                                          size_t *plaintext_name_size,
2208                                          struct dentry *ecryptfs_dir_dentry,
2209                                          const char *name, size_t name_size)
2210 {
2211         char *decoded_name;
2212         size_t decoded_name_size;
2213         size_t packet_size;
2214         int rc = 0;
2215
2216         if ((name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2217             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2218                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2219                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2220                         &ecryptfs_superblock_to_private(
2221                                 ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2222                 const char *orig_name = name;
2223                 size_t orig_name_size = name_size;
2224
2225                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2226                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2227                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2228                                               name, name_size);
2229                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2230                 if (!decoded_name) {
2231                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2232                                "to kmalloc [%zd] bytes\n", __func__,
2233                                decoded_name_size);
2234                         rc = -ENOMEM;
2235                         goto out;
2236                 }
2237                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2238                                               name, name_size);
2239                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2240                                                   plaintext_name_size,
2241                                                   &packet_size,
2242                                                   mount_crypt_stat,
2243                                                   decoded_name,
2244                                                   decoded_name_size);
2245                 if (rc) {
2246                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2247                                "from filename; copying through filename "
2248                                "as-is\n", __func__);
2249                         rc = ecryptfs_copy_filename(plaintext_name,
2250                                                     plaintext_name_size,
2251                                                     orig_name, orig_name_size);
2252                         goto out_free;
2253                 }
2254         } else {
2255                 rc = ecryptfs_copy_filename(plaintext_name,
2256                                             plaintext_name_size,
2257                                             name, name_size);
2258                 goto out;
2259         }
2260 out_free:
2261         kfree(decoded_name);
2262 out:
2263         return rc;
2264 }