eCryptfs: Remove unnecessary grow_file() function
[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 <linux/slab.h>
37 #include <asm/unaligned.h>
38 #include "ecryptfs_kernel.h"
39
40 static int
41 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
42                              struct page *dst_page, int dst_offset,
43                              struct page *src_page, int src_offset, int size,
44                              unsigned char *iv);
45 static int
46 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
47                              struct page *dst_page, int dst_offset,
48                              struct page *src_page, int src_offset, int size,
49                              unsigned char *iv);
50
51 /**
52  * ecryptfs_to_hex
53  * @dst: Buffer to take hex character representation of contents of
54  *       src; must be at least of size (src_size * 2)
55  * @src: Buffer to be converted to a hex string respresentation
56  * @src_size: number of bytes to convert
57  */
58 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
59 {
60         int x;
61
62         for (x = 0; x < src_size; x++)
63                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
64 }
65
66 /**
67  * ecryptfs_from_hex
68  * @dst: Buffer to take the bytes from src hex; must be at least of
69  *       size (src_size / 2)
70  * @src: Buffer to be converted from a hex string respresentation to raw value
71  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
72  */
73 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
74 {
75         int x;
76         char tmp[3] = { 0, };
77
78         for (x = 0; x < dst_size; x++) {
79                 tmp[0] = src[x * 2];
80                 tmp[1] = src[x * 2 + 1];
81                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
82         }
83 }
84
85 /**
86  * ecryptfs_calculate_md5 - calculates the md5 of @src
87  * @dst: Pointer to 16 bytes of allocated memory
88  * @crypt_stat: Pointer to crypt_stat struct for the current inode
89  * @src: Data to be md5'd
90  * @len: Length of @src
91  *
92  * Uses the allocated crypto context that crypt_stat references to
93  * generate the MD5 sum of the contents of src.
94  */
95 static int ecryptfs_calculate_md5(char *dst,
96                                   struct ecryptfs_crypt_stat *crypt_stat,
97                                   char *src, int len)
98 {
99         struct scatterlist sg;
100         struct hash_desc desc = {
101                 .tfm = crypt_stat->hash_tfm,
102                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
103         };
104         int rc = 0;
105
106         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
107         sg_init_one(&sg, (u8 *)src, len);
108         if (!desc.tfm) {
109                 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
110                                              CRYPTO_ALG_ASYNC);
111                 if (IS_ERR(desc.tfm)) {
112                         rc = PTR_ERR(desc.tfm);
113                         ecryptfs_printk(KERN_ERR, "Error attempting to "
114                                         "allocate crypto context; rc = [%d]\n",
115                                         rc);
116                         goto out;
117                 }
118                 crypt_stat->hash_tfm = desc.tfm;
119         }
120         rc = crypto_hash_init(&desc);
121         if (rc) {
122                 printk(KERN_ERR
123                        "%s: Error initializing crypto hash; rc = [%d]\n",
124                        __func__, rc);
125                 goto out;
126         }
127         rc = crypto_hash_update(&desc, &sg, len);
128         if (rc) {
129                 printk(KERN_ERR
130                        "%s: Error updating crypto hash; rc = [%d]\n",
131                        __func__, rc);
132                 goto out;
133         }
134         rc = crypto_hash_final(&desc, dst);
135         if (rc) {
136                 printk(KERN_ERR
137                        "%s: Error finalizing crypto hash; rc = [%d]\n",
138                        __func__, rc);
139                 goto out;
140         }
141 out:
142         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
143         return rc;
144 }
145
146 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
147                                                   char *cipher_name,
148                                                   char *chaining_modifier)
149 {
150         int cipher_name_len = strlen(cipher_name);
151         int chaining_modifier_len = strlen(chaining_modifier);
152         int algified_name_len;
153         int rc;
154
155         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
156         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
157         if (!(*algified_name)) {
158                 rc = -ENOMEM;
159                 goto out;
160         }
161         snprintf((*algified_name), algified_name_len, "%s(%s)",
162                  chaining_modifier, cipher_name);
163         rc = 0;
164 out:
165         return rc;
166 }
167
168 /**
169  * ecryptfs_derive_iv
170  * @iv: destination for the derived iv vale
171  * @crypt_stat: Pointer to crypt_stat struct for the current inode
172  * @offset: Offset of the extent whose IV we are to derive
173  *
174  * Generate the initialization vector from the given root IV and page
175  * offset.
176  *
177  * Returns zero on success; non-zero on error.
178  */
179 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
180                        loff_t offset)
181 {
182         int rc = 0;
183         char dst[MD5_DIGEST_SIZE];
184         char src[ECRYPTFS_MAX_IV_BYTES + 16];
185
186         if (unlikely(ecryptfs_verbosity > 0)) {
187                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
188                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
189         }
190         /* TODO: It is probably secure to just cast the least
191          * significant bits of the root IV into an unsigned long and
192          * add the offset to that rather than go through all this
193          * hashing business. -Halcrow */
194         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
195         memset((src + crypt_stat->iv_bytes), 0, 16);
196         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
197         if (unlikely(ecryptfs_verbosity > 0)) {
198                 ecryptfs_printk(KERN_DEBUG, "source:\n");
199                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
200         }
201         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
202                                     (crypt_stat->iv_bytes + 16));
203         if (rc) {
204                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
205                                 "MD5 while generating IV for a page\n");
206                 goto out;
207         }
208         memcpy(iv, dst, crypt_stat->iv_bytes);
209         if (unlikely(ecryptfs_verbosity > 0)) {
210                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
211                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
212         }
213 out:
214         return rc;
215 }
216
217 /**
218  * ecryptfs_init_crypt_stat
219  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
220  *
221  * Initialize the crypt_stat structure.
222  */
223 void
224 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
225 {
226         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
227         INIT_LIST_HEAD(&crypt_stat->keysig_list);
228         mutex_init(&crypt_stat->keysig_list_mutex);
229         mutex_init(&crypt_stat->cs_mutex);
230         mutex_init(&crypt_stat->cs_tfm_mutex);
231         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
232         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
233 }
234
235 /**
236  * ecryptfs_destroy_crypt_stat
237  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
238  *
239  * Releases all memory associated with a crypt_stat struct.
240  */
241 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
242 {
243         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
244
245         if (crypt_stat->tfm)
246                 crypto_free_blkcipher(crypt_stat->tfm);
247         if (crypt_stat->hash_tfm)
248                 crypto_free_hash(crypt_stat->hash_tfm);
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         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
255 }
256
257 void ecryptfs_destroy_mount_crypt_stat(
258         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
259 {
260         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
261
262         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
263                 return;
264         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
265         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
266                                  &mount_crypt_stat->global_auth_tok_list,
267                                  mount_crypt_stat_list) {
268                 list_del(&auth_tok->mount_crypt_stat_list);
269                 mount_crypt_stat->num_global_auth_toks--;
270                 if (auth_tok->global_auth_tok_key
271                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
272                         key_put(auth_tok->global_auth_tok_key);
273                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
274         }
275         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
276         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
277 }
278
279 /**
280  * virt_to_scatterlist
281  * @addr: Virtual address
282  * @size: Size of data; should be an even multiple of the block size
283  * @sg: Pointer to scatterlist array; set to NULL to obtain only
284  *      the number of scatterlist structs required in array
285  * @sg_size: Max array size
286  *
287  * Fills in a scatterlist array with page references for a passed
288  * virtual address.
289  *
290  * Returns the number of scatterlist structs in array used
291  */
292 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
293                         int sg_size)
294 {
295         int i = 0;
296         struct page *pg;
297         int offset;
298         int remainder_of_page;
299
300         sg_init_table(sg, sg_size);
301
302         while (size > 0 && i < sg_size) {
303                 pg = virt_to_page(addr);
304                 offset = offset_in_page(addr);
305                 if (sg)
306                         sg_set_page(&sg[i], pg, 0, offset);
307                 remainder_of_page = PAGE_CACHE_SIZE - offset;
308                 if (size >= remainder_of_page) {
309                         if (sg)
310                                 sg[i].length = remainder_of_page;
311                         addr += remainder_of_page;
312                         size -= remainder_of_page;
313                 } else {
314                         if (sg)
315                                 sg[i].length = size;
316                         addr += size;
317                         size = 0;
318                 }
319                 i++;
320         }
321         if (size > 0)
322                 return -ENOMEM;
323         return i;
324 }
325
326 /**
327  * encrypt_scatterlist
328  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
329  * @dest_sg: Destination of encrypted data
330  * @src_sg: Data to be encrypted
331  * @size: Length of data to be encrypted
332  * @iv: iv to use during encryption
333  *
334  * Returns the number of bytes encrypted; negative value on error
335  */
336 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
337                                struct scatterlist *dest_sg,
338                                struct scatterlist *src_sg, int size,
339                                unsigned char *iv)
340 {
341         struct blkcipher_desc desc = {
342                 .tfm = crypt_stat->tfm,
343                 .info = iv,
344                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
345         };
346         int rc = 0;
347
348         BUG_ON(!crypt_stat || !crypt_stat->tfm
349                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
350         if (unlikely(ecryptfs_verbosity > 0)) {
351                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
352                                 crypt_stat->key_size);
353                 ecryptfs_dump_hex(crypt_stat->key,
354                                   crypt_stat->key_size);
355         }
356         /* Consider doing this once, when the file is opened */
357         mutex_lock(&crypt_stat->cs_tfm_mutex);
358         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
359                 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
360                                              crypt_stat->key_size);
361                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
362         }
363         if (rc) {
364                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
365                                 rc);
366                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
367                 rc = -EINVAL;
368                 goto out;
369         }
370         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
371         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
372         mutex_unlock(&crypt_stat->cs_tfm_mutex);
373 out:
374         return rc;
375 }
376
377 /**
378  * ecryptfs_lower_offset_for_extent
379  *
380  * Convert an eCryptfs page index into a lower byte offset
381  */
382 static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
383                                              struct ecryptfs_crypt_stat *crypt_stat)
384 {
385         (*offset) = ecryptfs_lower_header_size(crypt_stat)
386                     + (crypt_stat->extent_size * extent_num);
387 }
388
389 /**
390  * ecryptfs_encrypt_extent
391  * @enc_extent_page: Allocated page into which to encrypt the data in
392  *                   @page
393  * @crypt_stat: crypt_stat containing cryptographic context for the
394  *              encryption operation
395  * @page: Page containing plaintext data extent to encrypt
396  * @extent_offset: Page extent offset for use in generating IV
397  *
398  * Encrypts one extent of data.
399  *
400  * Return zero on success; non-zero otherwise
401  */
402 static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
403                                    struct ecryptfs_crypt_stat *crypt_stat,
404                                    struct page *page,
405                                    unsigned long extent_offset)
406 {
407         loff_t extent_base;
408         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
409         int rc;
410
411         extent_base = (((loff_t)page->index)
412                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
413         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
414                                 (extent_base + extent_offset));
415         if (rc) {
416                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
417                         "extent [0x%.16llx]; rc = [%d]\n",
418                         (unsigned long long)(extent_base + extent_offset), rc);
419                 goto out;
420         }
421         if (unlikely(ecryptfs_verbosity > 0)) {
422                 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
423                                 "with iv:\n");
424                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
425                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
426                                 "encryption:\n");
427                 ecryptfs_dump_hex((char *)
428                                   (page_address(page)
429                                    + (extent_offset * crypt_stat->extent_size)),
430                                   8);
431         }
432         rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
433                                           page, (extent_offset
434                                                  * crypt_stat->extent_size),
435                                           crypt_stat->extent_size, extent_iv);
436         if (rc < 0) {
437                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
438                        "page->index = [%ld], extent_offset = [%ld]; "
439                        "rc = [%d]\n", __func__, page->index, extent_offset,
440                        rc);
441                 goto out;
442         }
443         rc = 0;
444         if (unlikely(ecryptfs_verbosity > 0)) {
445                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16llx]; "
446                         "rc = [%d]\n",
447                         (unsigned long long)(extent_base + extent_offset), rc);
448                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
449                                 "encryption:\n");
450                 ecryptfs_dump_hex((char *)(page_address(enc_extent_page)), 8);
451         }
452 out:
453         return rc;
454 }
455
456 /**
457  * ecryptfs_encrypt_page
458  * @page: Page mapped from the eCryptfs inode for the file; contains
459  *        decrypted content that needs to be encrypted (to a temporary
460  *        page; not in place) and written out to the lower file
461  *
462  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
463  * that eCryptfs pages may straddle the lower pages -- for instance,
464  * if the file was created on a machine with an 8K page size
465  * (resulting in an 8K header), and then the file is copied onto a
466  * host with a 32K page size, then when reading page 0 of the eCryptfs
467  * file, 24K of page 0 of the lower file will be read and decrypted,
468  * and then 8K of page 1 of the lower file will be read and decrypted.
469  *
470  * Returns zero on success; negative on error
471  */
472 int ecryptfs_encrypt_page(struct page *page)
473 {
474         struct inode *ecryptfs_inode;
475         struct ecryptfs_crypt_stat *crypt_stat;
476         char *enc_extent_virt;
477         struct page *enc_extent_page = NULL;
478         loff_t extent_offset;
479         int rc = 0;
480
481         ecryptfs_inode = page->mapping->host;
482         crypt_stat =
483                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
484         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
485         enc_extent_page = alloc_page(GFP_USER);
486         if (!enc_extent_page) {
487                 rc = -ENOMEM;
488                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
489                                 "encrypted extent\n");
490                 goto out;
491         }
492         enc_extent_virt = kmap(enc_extent_page);
493         for (extent_offset = 0;
494              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
495              extent_offset++) {
496                 loff_t offset;
497
498                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
499                                              extent_offset);
500                 if (rc) {
501                         printk(KERN_ERR "%s: Error encrypting extent; "
502                                "rc = [%d]\n", __func__, rc);
503                         goto out;
504                 }
505                 ecryptfs_lower_offset_for_extent(
506                         &offset, ((((loff_t)page->index)
507                                    * (PAGE_CACHE_SIZE
508                                       / crypt_stat->extent_size))
509                                   + extent_offset), crypt_stat);
510                 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
511                                           offset, crypt_stat->extent_size);
512                 if (rc < 0) {
513                         ecryptfs_printk(KERN_ERR, "Error attempting "
514                                         "to write lower page; rc = [%d]"
515                                         "\n", rc);
516                         goto out;
517                 }
518         }
519         rc = 0;
520 out:
521         if (enc_extent_page) {
522                 kunmap(enc_extent_page);
523                 __free_page(enc_extent_page);
524         }
525         return rc;
526 }
527
528 static int ecryptfs_decrypt_extent(struct page *page,
529                                    struct ecryptfs_crypt_stat *crypt_stat,
530                                    struct page *enc_extent_page,
531                                    unsigned long extent_offset)
532 {
533         loff_t extent_base;
534         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
535         int rc;
536
537         extent_base = (((loff_t)page->index)
538                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
539         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
540                                 (extent_base + extent_offset));
541         if (rc) {
542                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
543                         "extent [0x%.16llx]; rc = [%d]\n",
544                         (unsigned long long)(extent_base + extent_offset), rc);
545                 goto out;
546         }
547         if (unlikely(ecryptfs_verbosity > 0)) {
548                 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
549                                 "with iv:\n");
550                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
551                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
552                                 "decryption:\n");
553                 ecryptfs_dump_hex((char *)
554                                   (page_address(enc_extent_page)
555                                    + (extent_offset * crypt_stat->extent_size)),
556                                   8);
557         }
558         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
559                                           (extent_offset
560                                            * crypt_stat->extent_size),
561                                           enc_extent_page, 0,
562                                           crypt_stat->extent_size, extent_iv);
563         if (rc < 0) {
564                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
565                        "page->index = [%ld], extent_offset = [%ld]; "
566                        "rc = [%d]\n", __func__, page->index, extent_offset,
567                        rc);
568                 goto out;
569         }
570         rc = 0;
571         if (unlikely(ecryptfs_verbosity > 0)) {
572                 ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16llx]; "
573                         "rc = [%d]\n",
574                         (unsigned long long)(extent_base + extent_offset), rc);
575                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
576                                 "decryption:\n");
577                 ecryptfs_dump_hex((char *)(page_address(page)
578                                            + (extent_offset
579                                               * crypt_stat->extent_size)), 8);
580         }
581 out:
582         return rc;
583 }
584
585 /**
586  * ecryptfs_decrypt_page
587  * @page: Page mapped from the eCryptfs inode for the file; data read
588  *        and decrypted from the lower file will be written into this
589  *        page
590  *
591  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
592  * that eCryptfs pages may straddle the lower pages -- for instance,
593  * if the file was created on a machine with an 8K page size
594  * (resulting in an 8K header), and then the file is copied onto a
595  * host with a 32K page size, then when reading page 0 of the eCryptfs
596  * file, 24K of page 0 of the lower file will be read and decrypted,
597  * and then 8K of page 1 of the lower file will be read and decrypted.
598  *
599  * Returns zero on success; negative on error
600  */
601 int ecryptfs_decrypt_page(struct page *page)
602 {
603         struct inode *ecryptfs_inode;
604         struct ecryptfs_crypt_stat *crypt_stat;
605         char *enc_extent_virt;
606         struct page *enc_extent_page = NULL;
607         unsigned long extent_offset;
608         int rc = 0;
609
610         ecryptfs_inode = page->mapping->host;
611         crypt_stat =
612                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
613         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
614         enc_extent_page = alloc_page(GFP_USER);
615         if (!enc_extent_page) {
616                 rc = -ENOMEM;
617                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
618                                 "encrypted extent\n");
619                 goto out;
620         }
621         enc_extent_virt = kmap(enc_extent_page);
622         for (extent_offset = 0;
623              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
624              extent_offset++) {
625                 loff_t offset;
626
627                 ecryptfs_lower_offset_for_extent(
628                         &offset, ((page->index * (PAGE_CACHE_SIZE
629                                                   / crypt_stat->extent_size))
630                                   + extent_offset), crypt_stat);
631                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
632                                          crypt_stat->extent_size,
633                                          ecryptfs_inode);
634                 if (rc < 0) {
635                         ecryptfs_printk(KERN_ERR, "Error attempting "
636                                         "to read lower page; rc = [%d]"
637                                         "\n", rc);
638                         goto out;
639                 }
640                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
641                                              extent_offset);
642                 if (rc) {
643                         printk(KERN_ERR "%s: Error encrypting extent; "
644                                "rc = [%d]\n", __func__, rc);
645                         goto out;
646                 }
647         }
648 out:
649         if (enc_extent_page) {
650                 kunmap(enc_extent_page);
651                 __free_page(enc_extent_page);
652         }
653         return rc;
654 }
655
656 /**
657  * decrypt_scatterlist
658  * @crypt_stat: Cryptographic context
659  * @dest_sg: The destination scatterlist to decrypt into
660  * @src_sg: The source scatterlist to decrypt from
661  * @size: The number of bytes to decrypt
662  * @iv: The initialization vector to use for the decryption
663  *
664  * Returns the number of bytes decrypted; negative value on error
665  */
666 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
667                                struct scatterlist *dest_sg,
668                                struct scatterlist *src_sg, int size,
669                                unsigned char *iv)
670 {
671         struct blkcipher_desc desc = {
672                 .tfm = crypt_stat->tfm,
673                 .info = iv,
674                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
675         };
676         int rc = 0;
677
678         /* Consider doing this once, when the file is opened */
679         mutex_lock(&crypt_stat->cs_tfm_mutex);
680         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
681                                      crypt_stat->key_size);
682         if (rc) {
683                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
684                                 rc);
685                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
686                 rc = -EINVAL;
687                 goto out;
688         }
689         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
690         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
691         mutex_unlock(&crypt_stat->cs_tfm_mutex);
692         if (rc) {
693                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
694                                 rc);
695                 goto out;
696         }
697         rc = size;
698 out:
699         return rc;
700 }
701
702 /**
703  * ecryptfs_encrypt_page_offset
704  * @crypt_stat: The cryptographic context
705  * @dst_page: The page to encrypt into
706  * @dst_offset: The offset in the page to encrypt into
707  * @src_page: The page to encrypt from
708  * @src_offset: The offset in the page to encrypt from
709  * @size: The number of bytes to encrypt
710  * @iv: The initialization vector to use for the encryption
711  *
712  * Returns the number of bytes encrypted
713  */
714 static int
715 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
716                              struct page *dst_page, int dst_offset,
717                              struct page *src_page, int src_offset, int size,
718                              unsigned char *iv)
719 {
720         struct scatterlist src_sg, dst_sg;
721
722         sg_init_table(&src_sg, 1);
723         sg_init_table(&dst_sg, 1);
724
725         sg_set_page(&src_sg, src_page, size, src_offset);
726         sg_set_page(&dst_sg, dst_page, size, dst_offset);
727         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
728 }
729
730 /**
731  * ecryptfs_decrypt_page_offset
732  * @crypt_stat: The cryptographic context
733  * @dst_page: The page to decrypt into
734  * @dst_offset: The offset in the page to decrypt into
735  * @src_page: The page to decrypt from
736  * @src_offset: The offset in the page to decrypt from
737  * @size: The number of bytes to decrypt
738  * @iv: The initialization vector to use for the decryption
739  *
740  * Returns the number of bytes decrypted
741  */
742 static int
743 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
744                              struct page *dst_page, int dst_offset,
745                              struct page *src_page, int src_offset, int size,
746                              unsigned char *iv)
747 {
748         struct scatterlist src_sg, dst_sg;
749
750         sg_init_table(&src_sg, 1);
751         sg_set_page(&src_sg, src_page, size, src_offset);
752
753         sg_init_table(&dst_sg, 1);
754         sg_set_page(&dst_sg, dst_page, size, dst_offset);
755
756         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
757 }
758
759 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
760
761 /**
762  * ecryptfs_init_crypt_ctx
763  * @crypt_stat: Uninitialized crypt stats structure
764  *
765  * Initialize the crypto context.
766  *
767  * TODO: Performance: Keep a cache of initialized cipher contexts;
768  * only init if needed
769  */
770 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
771 {
772         char *full_alg_name;
773         int rc = -EINVAL;
774
775         if (!crypt_stat->cipher) {
776                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
777                 goto out;
778         }
779         ecryptfs_printk(KERN_DEBUG,
780                         "Initializing cipher [%s]; strlen = [%d]; "
781                         "key_size_bits = [%zd]\n",
782                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
783                         crypt_stat->key_size << 3);
784         if (crypt_stat->tfm) {
785                 rc = 0;
786                 goto out;
787         }
788         mutex_lock(&crypt_stat->cs_tfm_mutex);
789         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
790                                                     crypt_stat->cipher, "cbc");
791         if (rc)
792                 goto out_unlock;
793         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
794                                                  CRYPTO_ALG_ASYNC);
795         kfree(full_alg_name);
796         if (IS_ERR(crypt_stat->tfm)) {
797                 rc = PTR_ERR(crypt_stat->tfm);
798                 crypt_stat->tfm = NULL;
799                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
800                                 "Error initializing cipher [%s]\n",
801                                 crypt_stat->cipher);
802                 goto out_unlock;
803         }
804         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
805         rc = 0;
806 out_unlock:
807         mutex_unlock(&crypt_stat->cs_tfm_mutex);
808 out:
809         return rc;
810 }
811
812 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
813 {
814         int extent_size_tmp;
815
816         crypt_stat->extent_mask = 0xFFFFFFFF;
817         crypt_stat->extent_shift = 0;
818         if (crypt_stat->extent_size == 0)
819                 return;
820         extent_size_tmp = crypt_stat->extent_size;
821         while ((extent_size_tmp & 0x01) == 0) {
822                 extent_size_tmp >>= 1;
823                 crypt_stat->extent_mask <<= 1;
824                 crypt_stat->extent_shift++;
825         }
826 }
827
828 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
829 {
830         /* Default values; may be overwritten as we are parsing the
831          * packets. */
832         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
833         set_extent_mask_and_shift(crypt_stat);
834         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
835         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
836                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
837         else {
838                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
839                         crypt_stat->metadata_size =
840                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
841                 else
842                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
843         }
844 }
845
846 /**
847  * ecryptfs_compute_root_iv
848  * @crypt_stats
849  *
850  * On error, sets the root IV to all 0's.
851  */
852 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
853 {
854         int rc = 0;
855         char dst[MD5_DIGEST_SIZE];
856
857         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
858         BUG_ON(crypt_stat->iv_bytes <= 0);
859         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
860                 rc = -EINVAL;
861                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
862                                 "cannot generate root IV\n");
863                 goto out;
864         }
865         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
866                                     crypt_stat->key_size);
867         if (rc) {
868                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
869                                 "MD5 while generating root IV\n");
870                 goto out;
871         }
872         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
873 out:
874         if (rc) {
875                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
876                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
877         }
878         return rc;
879 }
880
881 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
882 {
883         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
884         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
885         ecryptfs_compute_root_iv(crypt_stat);
886         if (unlikely(ecryptfs_verbosity > 0)) {
887                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
888                 ecryptfs_dump_hex(crypt_stat->key,
889                                   crypt_stat->key_size);
890         }
891 }
892
893 /**
894  * ecryptfs_copy_mount_wide_flags_to_inode_flags
895  * @crypt_stat: The inode's cryptographic context
896  * @mount_crypt_stat: The mount point's cryptographic context
897  *
898  * This function propagates the mount-wide flags to individual inode
899  * flags.
900  */
901 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
902         struct ecryptfs_crypt_stat *crypt_stat,
903         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
904 {
905         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
906                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
907         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
908                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
909         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
910                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
911                 if (mount_crypt_stat->flags
912                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
913                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
914                 else if (mount_crypt_stat->flags
915                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
916                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
917         }
918 }
919
920 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
921         struct ecryptfs_crypt_stat *crypt_stat,
922         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
923 {
924         struct ecryptfs_global_auth_tok *global_auth_tok;
925         int rc = 0;
926
927         mutex_lock(&crypt_stat->keysig_list_mutex);
928         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
929
930         list_for_each_entry(global_auth_tok,
931                             &mount_crypt_stat->global_auth_tok_list,
932                             mount_crypt_stat_list) {
933                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
934                         continue;
935                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
936                 if (rc) {
937                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
938                         goto out;
939                 }
940         }
941
942 out:
943         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
944         mutex_unlock(&crypt_stat->keysig_list_mutex);
945         return rc;
946 }
947
948 /**
949  * ecryptfs_set_default_crypt_stat_vals
950  * @crypt_stat: The inode's cryptographic context
951  * @mount_crypt_stat: The mount point's cryptographic context
952  *
953  * Default values in the event that policy does not override them.
954  */
955 static void ecryptfs_set_default_crypt_stat_vals(
956         struct ecryptfs_crypt_stat *crypt_stat,
957         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
958 {
959         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
960                                                       mount_crypt_stat);
961         ecryptfs_set_default_sizes(crypt_stat);
962         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
963         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
964         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
965         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
966         crypt_stat->mount_crypt_stat = mount_crypt_stat;
967 }
968
969 /**
970  * ecryptfs_new_file_context
971  * @ecryptfs_dentry: The eCryptfs dentry
972  *
973  * If the crypto context for the file has not yet been established,
974  * this is where we do that.  Establishing a new crypto context
975  * involves the following decisions:
976  *  - What cipher to use?
977  *  - What set of authentication tokens to use?
978  * Here we just worry about getting enough information into the
979  * authentication tokens so that we know that they are available.
980  * We associate the available authentication tokens with the new file
981  * via the set of signatures in the crypt_stat struct.  Later, when
982  * the headers are actually written out, we may again defer to
983  * userspace to perform the encryption of the session key; for the
984  * foreseeable future, this will be the case with public key packets.
985  *
986  * Returns zero on success; non-zero otherwise
987  */
988 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
989 {
990         struct ecryptfs_crypt_stat *crypt_stat =
991             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
992         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
993             &ecryptfs_superblock_to_private(
994                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
995         int cipher_name_len;
996         int rc = 0;
997
998         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
999         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1000         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1001                                                       mount_crypt_stat);
1002         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1003                                                          mount_crypt_stat);
1004         if (rc) {
1005                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1006                        "to the inode key sigs; rc = [%d]\n", rc);
1007                 goto out;
1008         }
1009         cipher_name_len =
1010                 strlen(mount_crypt_stat->global_default_cipher_name);
1011         memcpy(crypt_stat->cipher,
1012                mount_crypt_stat->global_default_cipher_name,
1013                cipher_name_len);
1014         crypt_stat->cipher[cipher_name_len] = '\0';
1015         crypt_stat->key_size =
1016                 mount_crypt_stat->global_default_cipher_key_size;
1017         ecryptfs_generate_new_key(crypt_stat);
1018         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1019         if (rc)
1020                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1021                                 "context for cipher [%s]: rc = [%d]\n",
1022                                 crypt_stat->cipher, rc);
1023 out:
1024         return rc;
1025 }
1026
1027 /**
1028  * contains_ecryptfs_marker - check for the ecryptfs marker
1029  * @data: The data block in which to check
1030  *
1031  * Returns one if marker found; zero if not found
1032  */
1033 static int contains_ecryptfs_marker(char *data)
1034 {
1035         u32 m_1, m_2;
1036
1037         m_1 = get_unaligned_be32(data);
1038         m_2 = get_unaligned_be32(data + 4);
1039         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1040                 return 1;
1041         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1042                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1043                         MAGIC_ECRYPTFS_MARKER);
1044         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1045                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1046         return 0;
1047 }
1048
1049 struct ecryptfs_flag_map_elem {
1050         u32 file_flag;
1051         u32 local_flag;
1052 };
1053
1054 /* Add support for additional flags by adding elements here. */
1055 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1056         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1057         {0x00000002, ECRYPTFS_ENCRYPTED},
1058         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1059         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1060 };
1061
1062 /**
1063  * ecryptfs_process_flags
1064  * @crypt_stat: The cryptographic context
1065  * @page_virt: Source data to be parsed
1066  * @bytes_read: Updated with the number of bytes read
1067  *
1068  * Returns zero on success; non-zero if the flag set is invalid
1069  */
1070 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1071                                   char *page_virt, int *bytes_read)
1072 {
1073         int rc = 0;
1074         int i;
1075         u32 flags;
1076
1077         flags = get_unaligned_be32(page_virt);
1078         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1079                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1080                 if (flags & ecryptfs_flag_map[i].file_flag) {
1081                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1082                 } else
1083                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1084         /* Version is in top 8 bits of the 32-bit flag vector */
1085         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1086         (*bytes_read) = 4;
1087         return rc;
1088 }
1089
1090 /**
1091  * write_ecryptfs_marker
1092  * @page_virt: The pointer to in a page to begin writing the marker
1093  * @written: Number of bytes written
1094  *
1095  * Marker = 0x3c81b7f5
1096  */
1097 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1098 {
1099         u32 m_1, m_2;
1100
1101         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1102         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1103         put_unaligned_be32(m_1, page_virt);
1104         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1105         put_unaligned_be32(m_2, page_virt);
1106         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1107 }
1108
1109 void ecryptfs_write_crypt_stat_flags(char *page_virt,
1110                                      struct ecryptfs_crypt_stat *crypt_stat,
1111                                      size_t *written)
1112 {
1113         u32 flags = 0;
1114         int i;
1115
1116         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1117                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1118                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1119                         flags |= ecryptfs_flag_map[i].file_flag;
1120         /* Version is in top 8 bits of the 32-bit flag vector */
1121         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1122         put_unaligned_be32(flags, page_virt);
1123         (*written) = 4;
1124 }
1125
1126 struct ecryptfs_cipher_code_str_map_elem {
1127         char cipher_str[16];
1128         u8 cipher_code;
1129 };
1130
1131 /* Add support for additional ciphers by adding elements here. The
1132  * cipher_code is whatever OpenPGP applicatoins use to identify the
1133  * ciphers. List in order of probability. */
1134 static struct ecryptfs_cipher_code_str_map_elem
1135 ecryptfs_cipher_code_str_map[] = {
1136         {"aes",RFC2440_CIPHER_AES_128 },
1137         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1138         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1139         {"cast5", RFC2440_CIPHER_CAST_5},
1140         {"twofish", RFC2440_CIPHER_TWOFISH},
1141         {"cast6", RFC2440_CIPHER_CAST_6},
1142         {"aes", RFC2440_CIPHER_AES_192},
1143         {"aes", RFC2440_CIPHER_AES_256}
1144 };
1145
1146 /**
1147  * ecryptfs_code_for_cipher_string
1148  * @cipher_name: The string alias for the cipher
1149  * @key_bytes: Length of key in bytes; used for AES code selection
1150  *
1151  * Returns zero on no match, or the cipher code on match
1152  */
1153 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1154 {
1155         int i;
1156         u8 code = 0;
1157         struct ecryptfs_cipher_code_str_map_elem *map =
1158                 ecryptfs_cipher_code_str_map;
1159
1160         if (strcmp(cipher_name, "aes") == 0) {
1161                 switch (key_bytes) {
1162                 case 16:
1163                         code = RFC2440_CIPHER_AES_128;
1164                         break;
1165                 case 24:
1166                         code = RFC2440_CIPHER_AES_192;
1167                         break;
1168                 case 32:
1169                         code = RFC2440_CIPHER_AES_256;
1170                 }
1171         } else {
1172                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1173                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1174                                 code = map[i].cipher_code;
1175                                 break;
1176                         }
1177         }
1178         return code;
1179 }
1180
1181 /**
1182  * ecryptfs_cipher_code_to_string
1183  * @str: Destination to write out the cipher name
1184  * @cipher_code: The code to convert to cipher name string
1185  *
1186  * Returns zero on success
1187  */
1188 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1189 {
1190         int rc = 0;
1191         int i;
1192
1193         str[0] = '\0';
1194         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1195                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1196                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1197         if (str[0] == '\0') {
1198                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1199                                 "[%d]\n", cipher_code);
1200                 rc = -EINVAL;
1201         }
1202         return rc;
1203 }
1204
1205 int ecryptfs_read_and_validate_header_region(char *data,
1206                                              struct inode *ecryptfs_inode)
1207 {
1208         struct ecryptfs_crypt_stat *crypt_stat =
1209                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
1210         int rc;
1211
1212         if (crypt_stat->extent_size == 0)
1213                 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
1214         rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
1215                                  ecryptfs_inode);
1216         if (rc < 0) {
1217                 printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
1218                        __func__, rc);
1219                 goto out;
1220         }
1221         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) {
1222                 rc = -EINVAL;
1223         } else
1224                 rc = 0;
1225 out:
1226         return rc;
1227 }
1228
1229 void
1230 ecryptfs_write_header_metadata(char *virt,
1231                                struct ecryptfs_crypt_stat *crypt_stat,
1232                                size_t *written)
1233 {
1234         u32 header_extent_size;
1235         u16 num_header_extents_at_front;
1236
1237         header_extent_size = (u32)crypt_stat->extent_size;
1238         num_header_extents_at_front =
1239                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1240         put_unaligned_be32(header_extent_size, virt);
1241         virt += 4;
1242         put_unaligned_be16(num_header_extents_at_front, virt);
1243         (*written) = 6;
1244 }
1245
1246 struct kmem_cache *ecryptfs_header_cache_1;
1247 struct kmem_cache *ecryptfs_header_cache_2;
1248
1249 /**
1250  * ecryptfs_write_headers_virt
1251  * @page_virt: The virtual address to write the headers to
1252  * @max: The size of memory allocated at page_virt
1253  * @size: Set to the number of bytes written by this function
1254  * @crypt_stat: The cryptographic context
1255  * @ecryptfs_dentry: The eCryptfs dentry
1256  *
1257  * Format version: 1
1258  *
1259  *   Header Extent:
1260  *     Octets 0-7:        Unencrypted file size (big-endian)
1261  *     Octets 8-15:       eCryptfs special marker
1262  *     Octets 16-19:      Flags
1263  *      Octet 16:         File format version number (between 0 and 255)
1264  *      Octets 17-18:     Reserved
1265  *      Octet 19:         Bit 1 (lsb): Reserved
1266  *                        Bit 2: Encrypted?
1267  *                        Bits 3-8: Reserved
1268  *     Octets 20-23:      Header extent size (big-endian)
1269  *     Octets 24-25:      Number of header extents at front of file
1270  *                        (big-endian)
1271  *     Octet  26:         Begin RFC 2440 authentication token packet set
1272  *   Data Extent 0:
1273  *     Lower data (CBC encrypted)
1274  *   Data Extent 1:
1275  *     Lower data (CBC encrypted)
1276  *   ...
1277  *
1278  * Returns zero on success
1279  */
1280 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1281                                        size_t *size,
1282                                        struct ecryptfs_crypt_stat *crypt_stat,
1283                                        struct dentry *ecryptfs_dentry)
1284 {
1285         int rc;
1286         size_t written;
1287         size_t offset;
1288
1289         offset = ECRYPTFS_FILE_SIZE_BYTES;
1290         write_ecryptfs_marker((page_virt + offset), &written);
1291         offset += written;
1292         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1293                                         &written);
1294         offset += written;
1295         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1296                                        &written);
1297         offset += written;
1298         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1299                                               ecryptfs_dentry, &written,
1300                                               max - offset);
1301         if (rc)
1302                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1303                                 "set; rc = [%d]\n", rc);
1304         if (size) {
1305                 offset += written;
1306                 *size = offset;
1307         }
1308         return rc;
1309 }
1310
1311 static int
1312 ecryptfs_write_metadata_to_contents(struct dentry *ecryptfs_dentry,
1313                                     char *virt, size_t virt_len)
1314 {
1315         int rc;
1316
1317         rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
1318                                   0, virt_len);
1319         if (rc < 0)
1320                 printk(KERN_ERR "%s: Error attempting to write header "
1321                        "information to lower file; rc = [%d]\n", __func__, rc);
1322         else
1323                 rc = 0;
1324         return rc;
1325 }
1326
1327 static int
1328 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1329                                  char *page_virt, size_t size)
1330 {
1331         int rc;
1332
1333         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1334                                size, 0);
1335         return rc;
1336 }
1337
1338 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1339                                                unsigned int order)
1340 {
1341         struct page *page;
1342
1343         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1344         if (page)
1345                 return (unsigned long) page_address(page);
1346         return 0;
1347 }
1348
1349 /**
1350  * ecryptfs_write_metadata
1351  * @ecryptfs_dentry: The eCryptfs dentry
1352  *
1353  * Write the file headers out.  This will likely involve a userspace
1354  * callout, in which the session key is encrypted with one or more
1355  * public keys and/or the passphrase necessary to do the encryption is
1356  * retrieved via a prompt.  Exactly what happens at this point should
1357  * be policy-dependent.
1358  *
1359  * Returns zero on success; non-zero on error
1360  */
1361 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
1362 {
1363         struct ecryptfs_crypt_stat *crypt_stat =
1364                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1365         unsigned int order;
1366         char *virt;
1367         size_t virt_len;
1368         size_t size = 0;
1369         int rc = 0;
1370
1371         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1372                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1373                         printk(KERN_ERR "Key is invalid; bailing out\n");
1374                         rc = -EINVAL;
1375                         goto out;
1376                 }
1377         } else {
1378                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1379                        __func__);
1380                 rc = -EINVAL;
1381                 goto out;
1382         }
1383         virt_len = crypt_stat->metadata_size;
1384         order = get_order(virt_len);
1385         /* Released in this function */
1386         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1387         if (!virt) {
1388                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1389                 rc = -ENOMEM;
1390                 goto out;
1391         }
1392         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1393         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1394                                          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, virt,
1402                                                       size);
1403         else
1404                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_dentry, virt,
1405                                                          virt_len);
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_pages((unsigned long)virt, order);
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->metadata_size = (((size_t)num_header_extents_at_front
1431                                      * (size_t)header_extent_size));
1432         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1433         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1434             && (crypt_stat->metadata_size
1435                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1436                 rc = -EINVAL;
1437                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1438                        crypt_stat->metadata_size);
1439         }
1440         return rc;
1441 }
1442
1443 /**
1444  * set_default_header_data
1445  * @crypt_stat: The cryptographic context
1446  *
1447  * For version 0 file format; this function is only for backwards
1448  * compatibility for files created with the prior versions of
1449  * eCryptfs.
1450  */
1451 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1452 {
1453         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1454 }
1455
1456 /**
1457  * ecryptfs_read_headers_virt
1458  * @page_virt: The virtual address into which to read the headers
1459  * @crypt_stat: The cryptographic context
1460  * @ecryptfs_dentry: The eCryptfs dentry
1461  * @validate_header_size: Whether to validate the header size while reading
1462  *
1463  * Read/parse the header data. The header format is detailed in the
1464  * comment block for the ecryptfs_write_headers_virt() function.
1465  *
1466  * Returns zero on success
1467  */
1468 static int ecryptfs_read_headers_virt(char *page_virt,
1469                                       struct ecryptfs_crypt_stat *crypt_stat,
1470                                       struct dentry *ecryptfs_dentry,
1471                                       int validate_header_size)
1472 {
1473         int rc = 0;
1474         int offset;
1475         int bytes_read;
1476
1477         ecryptfs_set_default_sizes(crypt_stat);
1478         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1479                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1480         offset = ECRYPTFS_FILE_SIZE_BYTES;
1481         rc = contains_ecryptfs_marker(page_virt + offset);
1482         if (rc == 0) {
1483                 rc = -EINVAL;
1484                 goto out;
1485         }
1486         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1487         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1488                                     &bytes_read);
1489         if (rc) {
1490                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1491                 goto out;
1492         }
1493         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1494                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1495                                 "file version [%d] is supported by this "
1496                                 "version of eCryptfs\n",
1497                                 crypt_stat->file_version,
1498                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1499                 rc = -EINVAL;
1500                 goto out;
1501         }
1502         offset += bytes_read;
1503         if (crypt_stat->file_version >= 1) {
1504                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1505                                            &bytes_read, validate_header_size);
1506                 if (rc) {
1507                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1508                                         "metadata; rc = [%d]\n", rc);
1509                 }
1510                 offset += bytes_read;
1511         } else
1512                 set_default_header_data(crypt_stat);
1513         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1514                                        ecryptfs_dentry);
1515 out:
1516         return rc;
1517 }
1518
1519 /**
1520  * ecryptfs_read_xattr_region
1521  * @page_virt: The vitual address into which to read the xattr data
1522  * @ecryptfs_inode: The eCryptfs inode
1523  *
1524  * Attempts to read the crypto metadata from the extended attribute
1525  * region of the lower file.
1526  *
1527  * Returns zero on success; non-zero on error
1528  */
1529 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1530 {
1531         struct dentry *lower_dentry =
1532                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1533         ssize_t size;
1534         int rc = 0;
1535
1536         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1537                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1538         if (size < 0) {
1539                 if (unlikely(ecryptfs_verbosity > 0))
1540                         printk(KERN_INFO "Error attempting to read the [%s] "
1541                                "xattr from the lower file; return value = "
1542                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1543                 rc = -EINVAL;
1544                 goto out;
1545         }
1546 out:
1547         return rc;
1548 }
1549
1550 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1551                                             struct dentry *ecryptfs_dentry)
1552 {
1553         int rc;
1554
1555         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
1556         if (rc)
1557                 goto out;
1558         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1559                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1560                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1561                 rc = -EINVAL;
1562         }
1563 out:
1564         return rc;
1565 }
1566
1567 /**
1568  * ecryptfs_read_metadata
1569  *
1570  * Common entry point for reading file metadata. From here, we could
1571  * retrieve the header information from the header region of the file,
1572  * the xattr region of the file, or some other repostory that is
1573  * stored separately from the file itself. The current implementation
1574  * supports retrieving the metadata information from the file contents
1575  * and from the xattr region.
1576  *
1577  * Returns zero if valid headers found and parsed; non-zero otherwise
1578  */
1579 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1580 {
1581         int rc = 0;
1582         char *page_virt = NULL;
1583         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1584         struct ecryptfs_crypt_stat *crypt_stat =
1585             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1586         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1587                 &ecryptfs_superblock_to_private(
1588                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1589
1590         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1591                                                       mount_crypt_stat);
1592         /* Read the first page from the underlying file */
1593         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1594         if (!page_virt) {
1595                 rc = -ENOMEM;
1596                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1597                        __func__);
1598                 goto out;
1599         }
1600         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1601                                  ecryptfs_inode);
1602         if (rc >= 0)
1603                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1604                                                 ecryptfs_dentry,
1605                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1606         if (rc) {
1607                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1608                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1609                 if (rc) {
1610                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1611                                "file header region or xattr region\n");
1612                         rc = -EINVAL;
1613                         goto out;
1614                 }
1615                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1616                                                 ecryptfs_dentry,
1617                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1618                 if (rc) {
1619                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1620                                "file xattr region either\n");
1621                         rc = -EINVAL;
1622                 }
1623                 if (crypt_stat->mount_crypt_stat->flags
1624                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1625                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1626                 } else {
1627                         printk(KERN_WARNING "Attempt to access file with "
1628                                "crypto metadata only in the extended attribute "
1629                                "region, but eCryptfs was mounted without "
1630                                "xattr support enabled. eCryptfs will not treat "
1631                                "this like an encrypted file.\n");
1632                         rc = -EINVAL;
1633                 }
1634         }
1635 out:
1636         if (page_virt) {
1637                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1638                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1639         }
1640         return rc;
1641 }
1642
1643 /**
1644  * ecryptfs_encrypt_filename - encrypt filename
1645  *
1646  * CBC-encrypts the filename. We do not want to encrypt the same
1647  * filename with the same key and IV, which may happen with hard
1648  * links, so we prepend random bits to each filename.
1649  *
1650  * Returns zero on success; non-zero otherwise
1651  */
1652 static int
1653 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1654                           struct ecryptfs_crypt_stat *crypt_stat,
1655                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1656 {
1657         int rc = 0;
1658
1659         filename->encrypted_filename = NULL;
1660         filename->encrypted_filename_size = 0;
1661         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1662             || (mount_crypt_stat && (mount_crypt_stat->flags
1663                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1664                 size_t packet_size;
1665                 size_t remaining_bytes;
1666
1667                 rc = ecryptfs_write_tag_70_packet(
1668                         NULL, NULL,
1669                         &filename->encrypted_filename_size,
1670                         mount_crypt_stat, NULL,
1671                         filename->filename_size);
1672                 if (rc) {
1673                         printk(KERN_ERR "%s: Error attempting to get packet "
1674                                "size for tag 72; rc = [%d]\n", __func__,
1675                                rc);
1676                         filename->encrypted_filename_size = 0;
1677                         goto out;
1678                 }
1679                 filename->encrypted_filename =
1680                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1681                 if (!filename->encrypted_filename) {
1682                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1683                                "to kmalloc [%zd] bytes\n", __func__,
1684                                filename->encrypted_filename_size);
1685                         rc = -ENOMEM;
1686                         goto out;
1687                 }
1688                 remaining_bytes = filename->encrypted_filename_size;
1689                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1690                                                   &remaining_bytes,
1691                                                   &packet_size,
1692                                                   mount_crypt_stat,
1693                                                   filename->filename,
1694                                                   filename->filename_size);
1695                 if (rc) {
1696                         printk(KERN_ERR "%s: Error attempting to generate "
1697                                "tag 70 packet; rc = [%d]\n", __func__,
1698                                rc);
1699                         kfree(filename->encrypted_filename);
1700                         filename->encrypted_filename = NULL;
1701                         filename->encrypted_filename_size = 0;
1702                         goto out;
1703                 }
1704                 filename->encrypted_filename_size = packet_size;
1705         } else {
1706                 printk(KERN_ERR "%s: No support for requested filename "
1707                        "encryption method in this release\n", __func__);
1708                 rc = -EOPNOTSUPP;
1709                 goto out;
1710         }
1711 out:
1712         return rc;
1713 }
1714
1715 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1716                                   const char *name, size_t name_size)
1717 {
1718         int rc = 0;
1719
1720         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1721         if (!(*copied_name)) {
1722                 rc = -ENOMEM;
1723                 goto out;
1724         }
1725         memcpy((void *)(*copied_name), (void *)name, name_size);
1726         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1727                                                  * in printing out the
1728                                                  * string in debug
1729                                                  * messages */
1730         (*copied_name_size) = name_size;
1731 out:
1732         return rc;
1733 }
1734
1735 /**
1736  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1737  * @key_tfm: Crypto context for key material, set by this function
1738  * @cipher_name: Name of the cipher
1739  * @key_size: Size of the key in bytes
1740  *
1741  * Returns zero on success. Any crypto_tfm structs allocated here
1742  * should be released by other functions, such as on a superblock put
1743  * event, regardless of whether this function succeeds for fails.
1744  */
1745 static int
1746 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1747                             char *cipher_name, size_t *key_size)
1748 {
1749         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1750         char *full_alg_name = NULL;
1751         int rc;
1752
1753         *key_tfm = NULL;
1754         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1755                 rc = -EINVAL;
1756                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1757                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1758                 goto out;
1759         }
1760         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1761                                                     "ecb");
1762         if (rc)
1763                 goto out;
1764         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1765         if (IS_ERR(*key_tfm)) {
1766                 rc = PTR_ERR(*key_tfm);
1767                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1768                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1769                 goto out;
1770         }
1771         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1772         if (*key_size == 0) {
1773                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1774
1775                 *key_size = alg->max_keysize;
1776         }
1777         get_random_bytes(dummy_key, *key_size);
1778         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1779         if (rc) {
1780                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1781                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1782                        rc);
1783                 rc = -EINVAL;
1784                 goto out;
1785         }
1786 out:
1787         kfree(full_alg_name);
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 __init 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                 } else {
2172                         rc = -EOPNOTSUPP;
2173                 }
2174                 if (rc) {
2175                         printk(KERN_ERR "%s: Error attempting to encode "
2176                                "encrypted filename; rc = [%d]\n", __func__,
2177                                rc);
2178                         kfree((*encoded_name));
2179                         (*encoded_name) = NULL;
2180                         (*encoded_name_size) = 0;
2181                 }
2182                 kfree(filename->encrypted_filename);
2183                 kfree(filename);
2184         } else {
2185                 rc = ecryptfs_copy_filename(encoded_name,
2186                                             encoded_name_size,
2187                                             name, name_size);
2188         }
2189 out:
2190         return rc;
2191 }
2192
2193 /**
2194  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2195  * @plaintext_name: The plaintext name
2196  * @plaintext_name_size: The plaintext name size
2197  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2198  * @name: The filename in cipher text
2199  * @name_size: The cipher text name size
2200  *
2201  * Decrypts and decodes the filename.
2202  *
2203  * Returns zero on error; non-zero otherwise
2204  */
2205 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2206                                          size_t *plaintext_name_size,
2207                                          struct dentry *ecryptfs_dir_dentry,
2208                                          const char *name, size_t name_size)
2209 {
2210         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2211                 &ecryptfs_superblock_to_private(
2212                         ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2213         char *decoded_name;
2214         size_t decoded_name_size;
2215         size_t packet_size;
2216         int rc = 0;
2217
2218         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2219             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2220             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2221             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2222                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2223                 const char *orig_name = name;
2224                 size_t orig_name_size = name_size;
2225
2226                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2227                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2228                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2229                                               name, name_size);
2230                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2231                 if (!decoded_name) {
2232                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2233                                "to kmalloc [%zd] bytes\n", __func__,
2234                                decoded_name_size);
2235                         rc = -ENOMEM;
2236                         goto out;
2237                 }
2238                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2239                                               name, name_size);
2240                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2241                                                   plaintext_name_size,
2242                                                   &packet_size,
2243                                                   mount_crypt_stat,
2244                                                   decoded_name,
2245                                                   decoded_name_size);
2246                 if (rc) {
2247                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2248                                "from filename; copying through filename "
2249                                "as-is\n", __func__);
2250                         rc = ecryptfs_copy_filename(plaintext_name,
2251                                                     plaintext_name_size,
2252                                                     orig_name, orig_name_size);
2253                         goto out_free;
2254                 }
2255         } else {
2256                 rc = ecryptfs_copy_filename(plaintext_name,
2257                                             plaintext_name_size,
2258                                             name, name_size);
2259                 goto out;
2260         }
2261 out_free:
2262         kfree(decoded_name);
2263 out:
2264         return rc;
2265 }