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