Merge tag 'ecryptfs-3.9-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git...
[~shefty/rdma-dev.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                 sg_set_page(&sg[i], pg, 0, offset);
305                 remainder_of_page = PAGE_CACHE_SIZE - offset;
306                 if (size >= remainder_of_page) {
307                         sg[i].length = remainder_of_page;
308                         addr += remainder_of_page;
309                         size -= remainder_of_page;
310                 } else {
311                         sg[i].length = size;
312                         addr += size;
313                         size = 0;
314                 }
315                 i++;
316         }
317         if (size > 0)
318                 return -ENOMEM;
319         return i;
320 }
321
322 /**
323  * encrypt_scatterlist
324  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
325  * @dest_sg: Destination of encrypted data
326  * @src_sg: Data to be encrypted
327  * @size: Length of data to be encrypted
328  * @iv: iv to use during encryption
329  *
330  * Returns the number of bytes encrypted; negative value on error
331  */
332 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
333                                struct scatterlist *dest_sg,
334                                struct scatterlist *src_sg, int size,
335                                unsigned char *iv)
336 {
337         struct blkcipher_desc desc = {
338                 .tfm = crypt_stat->tfm,
339                 .info = iv,
340                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
341         };
342         int rc = 0;
343
344         BUG_ON(!crypt_stat || !crypt_stat->tfm
345                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
346         if (unlikely(ecryptfs_verbosity > 0)) {
347                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
348                                 crypt_stat->key_size);
349                 ecryptfs_dump_hex(crypt_stat->key,
350                                   crypt_stat->key_size);
351         }
352         /* Consider doing this once, when the file is opened */
353         mutex_lock(&crypt_stat->cs_tfm_mutex);
354         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
355                 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
356                                              crypt_stat->key_size);
357                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
358         }
359         if (rc) {
360                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
361                                 rc);
362                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
363                 rc = -EINVAL;
364                 goto out;
365         }
366         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
367         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
368         mutex_unlock(&crypt_stat->cs_tfm_mutex);
369 out:
370         return rc;
371 }
372
373 /**
374  * ecryptfs_lower_offset_for_extent
375  *
376  * Convert an eCryptfs page index into a lower byte offset
377  */
378 static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
379                                              struct ecryptfs_crypt_stat *crypt_stat)
380 {
381         (*offset) = ecryptfs_lower_header_size(crypt_stat)
382                     + (crypt_stat->extent_size * extent_num);
383 }
384
385 /**
386  * ecryptfs_encrypt_extent
387  * @enc_extent_page: Allocated page into which to encrypt the data in
388  *                   @page
389  * @crypt_stat: crypt_stat containing cryptographic context for the
390  *              encryption operation
391  * @page: Page containing plaintext data extent to encrypt
392  * @extent_offset: Page extent offset for use in generating IV
393  *
394  * Encrypts one extent of data.
395  *
396  * Return zero on success; non-zero otherwise
397  */
398 static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
399                                    struct ecryptfs_crypt_stat *crypt_stat,
400                                    struct page *page,
401                                    unsigned long extent_offset)
402 {
403         loff_t extent_base;
404         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
405         int rc;
406
407         extent_base = (((loff_t)page->index)
408                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
409         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
410                                 (extent_base + extent_offset));
411         if (rc) {
412                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
413                         "extent [0x%.16llx]; rc = [%d]\n",
414                         (unsigned long long)(extent_base + extent_offset), rc);
415                 goto out;
416         }
417         rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
418                                           page, (extent_offset
419                                                  * crypt_stat->extent_size),
420                                           crypt_stat->extent_size, extent_iv);
421         if (rc < 0) {
422                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
423                        "page->index = [%ld], extent_offset = [%ld]; "
424                        "rc = [%d]\n", __func__, page->index, extent_offset,
425                        rc);
426                 goto out;
427         }
428         rc = 0;
429 out:
430         return rc;
431 }
432
433 /**
434  * ecryptfs_encrypt_page
435  * @page: Page mapped from the eCryptfs inode for the file; contains
436  *        decrypted content that needs to be encrypted (to a temporary
437  *        page; not in place) and written out to the lower file
438  *
439  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
440  * that eCryptfs pages may straddle the lower pages -- for instance,
441  * if the file was created on a machine with an 8K page size
442  * (resulting in an 8K header), and then the file is copied onto a
443  * host with a 32K page size, then when reading page 0 of the eCryptfs
444  * file, 24K of page 0 of the lower file will be read and decrypted,
445  * and then 8K of page 1 of the lower file will be read and decrypted.
446  *
447  * Returns zero on success; negative on error
448  */
449 int ecryptfs_encrypt_page(struct page *page)
450 {
451         struct inode *ecryptfs_inode;
452         struct ecryptfs_crypt_stat *crypt_stat;
453         char *enc_extent_virt;
454         struct page *enc_extent_page = NULL;
455         loff_t extent_offset;
456         int rc = 0;
457
458         ecryptfs_inode = page->mapping->host;
459         crypt_stat =
460                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
461         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
462         enc_extent_page = alloc_page(GFP_USER);
463         if (!enc_extent_page) {
464                 rc = -ENOMEM;
465                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
466                                 "encrypted extent\n");
467                 goto out;
468         }
469         enc_extent_virt = kmap(enc_extent_page);
470         for (extent_offset = 0;
471              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
472              extent_offset++) {
473                 loff_t offset;
474
475                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
476                                              extent_offset);
477                 if (rc) {
478                         printk(KERN_ERR "%s: Error encrypting extent; "
479                                "rc = [%d]\n", __func__, rc);
480                         goto out;
481                 }
482                 ecryptfs_lower_offset_for_extent(
483                         &offset, ((((loff_t)page->index)
484                                    * (PAGE_CACHE_SIZE
485                                       / crypt_stat->extent_size))
486                                   + extent_offset), crypt_stat);
487                 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
488                                           offset, crypt_stat->extent_size);
489                 if (rc < 0) {
490                         ecryptfs_printk(KERN_ERR, "Error attempting "
491                                         "to write lower page; rc = [%d]"
492                                         "\n", rc);
493                         goto out;
494                 }
495         }
496         rc = 0;
497 out:
498         if (enc_extent_page) {
499                 kunmap(enc_extent_page);
500                 __free_page(enc_extent_page);
501         }
502         return rc;
503 }
504
505 static int ecryptfs_decrypt_extent(struct page *page,
506                                    struct ecryptfs_crypt_stat *crypt_stat,
507                                    struct page *enc_extent_page,
508                                    unsigned long extent_offset)
509 {
510         loff_t extent_base;
511         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
512         int rc;
513
514         extent_base = (((loff_t)page->index)
515                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
516         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
517                                 (extent_base + extent_offset));
518         if (rc) {
519                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
520                         "extent [0x%.16llx]; rc = [%d]\n",
521                         (unsigned long long)(extent_base + extent_offset), rc);
522                 goto out;
523         }
524         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
525                                           (extent_offset
526                                            * crypt_stat->extent_size),
527                                           enc_extent_page, 0,
528                                           crypt_stat->extent_size, extent_iv);
529         if (rc < 0) {
530                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
531                        "page->index = [%ld], extent_offset = [%ld]; "
532                        "rc = [%d]\n", __func__, page->index, extent_offset,
533                        rc);
534                 goto out;
535         }
536         rc = 0;
537 out:
538         return rc;
539 }
540
541 /**
542  * ecryptfs_decrypt_page
543  * @page: Page mapped from the eCryptfs inode for the file; data read
544  *        and decrypted from the lower file will be written into this
545  *        page
546  *
547  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
548  * that eCryptfs pages may straddle the lower pages -- for instance,
549  * if the file was created on a machine with an 8K page size
550  * (resulting in an 8K header), and then the file is copied onto a
551  * host with a 32K page size, then when reading page 0 of the eCryptfs
552  * file, 24K of page 0 of the lower file will be read and decrypted,
553  * and then 8K of page 1 of the lower file will be read and decrypted.
554  *
555  * Returns zero on success; negative on error
556  */
557 int ecryptfs_decrypt_page(struct page *page)
558 {
559         struct inode *ecryptfs_inode;
560         struct ecryptfs_crypt_stat *crypt_stat;
561         char *enc_extent_virt;
562         struct page *enc_extent_page = NULL;
563         unsigned long extent_offset;
564         int rc = 0;
565
566         ecryptfs_inode = page->mapping->host;
567         crypt_stat =
568                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
569         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
570         enc_extent_page = alloc_page(GFP_USER);
571         if (!enc_extent_page) {
572                 rc = -ENOMEM;
573                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
574                                 "encrypted extent\n");
575                 goto out;
576         }
577         enc_extent_virt = kmap(enc_extent_page);
578         for (extent_offset = 0;
579              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
580              extent_offset++) {
581                 loff_t offset;
582
583                 ecryptfs_lower_offset_for_extent(
584                         &offset, ((page->index * (PAGE_CACHE_SIZE
585                                                   / crypt_stat->extent_size))
586                                   + extent_offset), crypt_stat);
587                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
588                                          crypt_stat->extent_size,
589                                          ecryptfs_inode);
590                 if (rc < 0) {
591                         ecryptfs_printk(KERN_ERR, "Error attempting "
592                                         "to read lower page; rc = [%d]"
593                                         "\n", rc);
594                         goto out;
595                 }
596                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
597                                              extent_offset);
598                 if (rc) {
599                         printk(KERN_ERR "%s: Error encrypting extent; "
600                                "rc = [%d]\n", __func__, rc);
601                         goto out;
602                 }
603         }
604 out:
605         if (enc_extent_page) {
606                 kunmap(enc_extent_page);
607                 __free_page(enc_extent_page);
608         }
609         return rc;
610 }
611
612 /**
613  * decrypt_scatterlist
614  * @crypt_stat: Cryptographic context
615  * @dest_sg: The destination scatterlist to decrypt into
616  * @src_sg: The source scatterlist to decrypt from
617  * @size: The number of bytes to decrypt
618  * @iv: The initialization vector to use for the decryption
619  *
620  * Returns the number of bytes decrypted; negative value on error
621  */
622 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
623                                struct scatterlist *dest_sg,
624                                struct scatterlist *src_sg, int size,
625                                unsigned char *iv)
626 {
627         struct blkcipher_desc desc = {
628                 .tfm = crypt_stat->tfm,
629                 .info = iv,
630                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
631         };
632         int rc = 0;
633
634         /* Consider doing this once, when the file is opened */
635         mutex_lock(&crypt_stat->cs_tfm_mutex);
636         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
637                                      crypt_stat->key_size);
638         if (rc) {
639                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
640                                 rc);
641                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
642                 rc = -EINVAL;
643                 goto out;
644         }
645         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
646         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
647         mutex_unlock(&crypt_stat->cs_tfm_mutex);
648         if (rc) {
649                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
650                                 rc);
651                 goto out;
652         }
653         rc = size;
654 out:
655         return rc;
656 }
657
658 /**
659  * ecryptfs_encrypt_page_offset
660  * @crypt_stat: The cryptographic context
661  * @dst_page: The page to encrypt into
662  * @dst_offset: The offset in the page to encrypt into
663  * @src_page: The page to encrypt from
664  * @src_offset: The offset in the page to encrypt from
665  * @size: The number of bytes to encrypt
666  * @iv: The initialization vector to use for the encryption
667  *
668  * Returns the number of bytes encrypted
669  */
670 static int
671 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
672                              struct page *dst_page, int dst_offset,
673                              struct page *src_page, int src_offset, int size,
674                              unsigned char *iv)
675 {
676         struct scatterlist src_sg, dst_sg;
677
678         sg_init_table(&src_sg, 1);
679         sg_init_table(&dst_sg, 1);
680
681         sg_set_page(&src_sg, src_page, size, src_offset);
682         sg_set_page(&dst_sg, dst_page, size, dst_offset);
683         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
684 }
685
686 /**
687  * ecryptfs_decrypt_page_offset
688  * @crypt_stat: The cryptographic context
689  * @dst_page: The page to decrypt into
690  * @dst_offset: The offset in the page to decrypt into
691  * @src_page: The page to decrypt from
692  * @src_offset: The offset in the page to decrypt from
693  * @size: The number of bytes to decrypt
694  * @iv: The initialization vector to use for the decryption
695  *
696  * Returns the number of bytes decrypted
697  */
698 static int
699 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
700                              struct page *dst_page, int dst_offset,
701                              struct page *src_page, int src_offset, int size,
702                              unsigned char *iv)
703 {
704         struct scatterlist src_sg, dst_sg;
705
706         sg_init_table(&src_sg, 1);
707         sg_set_page(&src_sg, src_page, size, src_offset);
708
709         sg_init_table(&dst_sg, 1);
710         sg_set_page(&dst_sg, dst_page, size, dst_offset);
711
712         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
713 }
714
715 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
716
717 /**
718  * ecryptfs_init_crypt_ctx
719  * @crypt_stat: Uninitialized crypt stats structure
720  *
721  * Initialize the crypto context.
722  *
723  * TODO: Performance: Keep a cache of initialized cipher contexts;
724  * only init if needed
725  */
726 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
727 {
728         char *full_alg_name;
729         int rc = -EINVAL;
730
731         if (!crypt_stat->cipher) {
732                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
733                 goto out;
734         }
735         ecryptfs_printk(KERN_DEBUG,
736                         "Initializing cipher [%s]; strlen = [%d]; "
737                         "key_size_bits = [%zd]\n",
738                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
739                         crypt_stat->key_size << 3);
740         if (crypt_stat->tfm) {
741                 rc = 0;
742                 goto out;
743         }
744         mutex_lock(&crypt_stat->cs_tfm_mutex);
745         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
746                                                     crypt_stat->cipher, "cbc");
747         if (rc)
748                 goto out_unlock;
749         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
750                                                  CRYPTO_ALG_ASYNC);
751         kfree(full_alg_name);
752         if (IS_ERR(crypt_stat->tfm)) {
753                 rc = PTR_ERR(crypt_stat->tfm);
754                 crypt_stat->tfm = NULL;
755                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
756                                 "Error initializing cipher [%s]\n",
757                                 crypt_stat->cipher);
758                 goto out_unlock;
759         }
760         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
761         rc = 0;
762 out_unlock:
763         mutex_unlock(&crypt_stat->cs_tfm_mutex);
764 out:
765         return rc;
766 }
767
768 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
769 {
770         int extent_size_tmp;
771
772         crypt_stat->extent_mask = 0xFFFFFFFF;
773         crypt_stat->extent_shift = 0;
774         if (crypt_stat->extent_size == 0)
775                 return;
776         extent_size_tmp = crypt_stat->extent_size;
777         while ((extent_size_tmp & 0x01) == 0) {
778                 extent_size_tmp >>= 1;
779                 crypt_stat->extent_mask <<= 1;
780                 crypt_stat->extent_shift++;
781         }
782 }
783
784 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
785 {
786         /* Default values; may be overwritten as we are parsing the
787          * packets. */
788         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
789         set_extent_mask_and_shift(crypt_stat);
790         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
791         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
792                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
793         else {
794                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
795                         crypt_stat->metadata_size =
796                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
797                 else
798                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
799         }
800 }
801
802 /**
803  * ecryptfs_compute_root_iv
804  * @crypt_stats
805  *
806  * On error, sets the root IV to all 0's.
807  */
808 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
809 {
810         int rc = 0;
811         char dst[MD5_DIGEST_SIZE];
812
813         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
814         BUG_ON(crypt_stat->iv_bytes <= 0);
815         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
816                 rc = -EINVAL;
817                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
818                                 "cannot generate root IV\n");
819                 goto out;
820         }
821         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
822                                     crypt_stat->key_size);
823         if (rc) {
824                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
825                                 "MD5 while generating root IV\n");
826                 goto out;
827         }
828         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
829 out:
830         if (rc) {
831                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
832                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
833         }
834         return rc;
835 }
836
837 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
838 {
839         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
840         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
841         ecryptfs_compute_root_iv(crypt_stat);
842         if (unlikely(ecryptfs_verbosity > 0)) {
843                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
844                 ecryptfs_dump_hex(crypt_stat->key,
845                                   crypt_stat->key_size);
846         }
847 }
848
849 /**
850  * ecryptfs_copy_mount_wide_flags_to_inode_flags
851  * @crypt_stat: The inode's cryptographic context
852  * @mount_crypt_stat: The mount point's cryptographic context
853  *
854  * This function propagates the mount-wide flags to individual inode
855  * flags.
856  */
857 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
858         struct ecryptfs_crypt_stat *crypt_stat,
859         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
860 {
861         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
862                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
863         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
864                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
865         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
866                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
867                 if (mount_crypt_stat->flags
868                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
869                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
870                 else if (mount_crypt_stat->flags
871                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
872                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
873         }
874 }
875
876 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
877         struct ecryptfs_crypt_stat *crypt_stat,
878         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
879 {
880         struct ecryptfs_global_auth_tok *global_auth_tok;
881         int rc = 0;
882
883         mutex_lock(&crypt_stat->keysig_list_mutex);
884         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
885
886         list_for_each_entry(global_auth_tok,
887                             &mount_crypt_stat->global_auth_tok_list,
888                             mount_crypt_stat_list) {
889                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
890                         continue;
891                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
892                 if (rc) {
893                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
894                         goto out;
895                 }
896         }
897
898 out:
899         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
900         mutex_unlock(&crypt_stat->keysig_list_mutex);
901         return rc;
902 }
903
904 /**
905  * ecryptfs_set_default_crypt_stat_vals
906  * @crypt_stat: The inode's cryptographic context
907  * @mount_crypt_stat: The mount point's cryptographic context
908  *
909  * Default values in the event that policy does not override them.
910  */
911 static void ecryptfs_set_default_crypt_stat_vals(
912         struct ecryptfs_crypt_stat *crypt_stat,
913         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
914 {
915         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
916                                                       mount_crypt_stat);
917         ecryptfs_set_default_sizes(crypt_stat);
918         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
919         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
920         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
921         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
922         crypt_stat->mount_crypt_stat = mount_crypt_stat;
923 }
924
925 /**
926  * ecryptfs_new_file_context
927  * @ecryptfs_inode: The eCryptfs inode
928  *
929  * If the crypto context for the file has not yet been established,
930  * this is where we do that.  Establishing a new crypto context
931  * involves the following decisions:
932  *  - What cipher to use?
933  *  - What set of authentication tokens to use?
934  * Here we just worry about getting enough information into the
935  * authentication tokens so that we know that they are available.
936  * We associate the available authentication tokens with the new file
937  * via the set of signatures in the crypt_stat struct.  Later, when
938  * the headers are actually written out, we may again defer to
939  * userspace to perform the encryption of the session key; for the
940  * foreseeable future, this will be the case with public key packets.
941  *
942  * Returns zero on success; non-zero otherwise
943  */
944 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
945 {
946         struct ecryptfs_crypt_stat *crypt_stat =
947             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
948         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
949             &ecryptfs_superblock_to_private(
950                     ecryptfs_inode->i_sb)->mount_crypt_stat;
951         int cipher_name_len;
952         int rc = 0;
953
954         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
955         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
956         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
957                                                       mount_crypt_stat);
958         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
959                                                          mount_crypt_stat);
960         if (rc) {
961                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
962                        "to the inode key sigs; rc = [%d]\n", rc);
963                 goto out;
964         }
965         cipher_name_len =
966                 strlen(mount_crypt_stat->global_default_cipher_name);
967         memcpy(crypt_stat->cipher,
968                mount_crypt_stat->global_default_cipher_name,
969                cipher_name_len);
970         crypt_stat->cipher[cipher_name_len] = '\0';
971         crypt_stat->key_size =
972                 mount_crypt_stat->global_default_cipher_key_size;
973         ecryptfs_generate_new_key(crypt_stat);
974         rc = ecryptfs_init_crypt_ctx(crypt_stat);
975         if (rc)
976                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
977                                 "context for cipher [%s]: rc = [%d]\n",
978                                 crypt_stat->cipher, rc);
979 out:
980         return rc;
981 }
982
983 /**
984  * ecryptfs_validate_marker - check for the ecryptfs marker
985  * @data: The data block in which to check
986  *
987  * Returns zero if marker found; -EINVAL if not found
988  */
989 static int ecryptfs_validate_marker(char *data)
990 {
991         u32 m_1, m_2;
992
993         m_1 = get_unaligned_be32(data);
994         m_2 = get_unaligned_be32(data + 4);
995         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
996                 return 0;
997         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
998                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
999                         MAGIC_ECRYPTFS_MARKER);
1000         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1001                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1002         return -EINVAL;
1003 }
1004
1005 struct ecryptfs_flag_map_elem {
1006         u32 file_flag;
1007         u32 local_flag;
1008 };
1009
1010 /* Add support for additional flags by adding elements here. */
1011 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1012         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1013         {0x00000002, ECRYPTFS_ENCRYPTED},
1014         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1015         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1016 };
1017
1018 /**
1019  * ecryptfs_process_flags
1020  * @crypt_stat: The cryptographic context
1021  * @page_virt: Source data to be parsed
1022  * @bytes_read: Updated with the number of bytes read
1023  *
1024  * Returns zero on success; non-zero if the flag set is invalid
1025  */
1026 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1027                                   char *page_virt, int *bytes_read)
1028 {
1029         int rc = 0;
1030         int i;
1031         u32 flags;
1032
1033         flags = get_unaligned_be32(page_virt);
1034         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1035                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1036                 if (flags & ecryptfs_flag_map[i].file_flag) {
1037                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1038                 } else
1039                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1040         /* Version is in top 8 bits of the 32-bit flag vector */
1041         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1042         (*bytes_read) = 4;
1043         return rc;
1044 }
1045
1046 /**
1047  * write_ecryptfs_marker
1048  * @page_virt: The pointer to in a page to begin writing the marker
1049  * @written: Number of bytes written
1050  *
1051  * Marker = 0x3c81b7f5
1052  */
1053 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1054 {
1055         u32 m_1, m_2;
1056
1057         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1058         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1059         put_unaligned_be32(m_1, page_virt);
1060         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1061         put_unaligned_be32(m_2, page_virt);
1062         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1063 }
1064
1065 void ecryptfs_write_crypt_stat_flags(char *page_virt,
1066                                      struct ecryptfs_crypt_stat *crypt_stat,
1067                                      size_t *written)
1068 {
1069         u32 flags = 0;
1070         int i;
1071
1072         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1073                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1074                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1075                         flags |= ecryptfs_flag_map[i].file_flag;
1076         /* Version is in top 8 bits of the 32-bit flag vector */
1077         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1078         put_unaligned_be32(flags, page_virt);
1079         (*written) = 4;
1080 }
1081
1082 struct ecryptfs_cipher_code_str_map_elem {
1083         char cipher_str[16];
1084         u8 cipher_code;
1085 };
1086
1087 /* Add support for additional ciphers by adding elements here. The
1088  * cipher_code is whatever OpenPGP applicatoins use to identify the
1089  * ciphers. List in order of probability. */
1090 static struct ecryptfs_cipher_code_str_map_elem
1091 ecryptfs_cipher_code_str_map[] = {
1092         {"aes",RFC2440_CIPHER_AES_128 },
1093         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1094         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1095         {"cast5", RFC2440_CIPHER_CAST_5},
1096         {"twofish", RFC2440_CIPHER_TWOFISH},
1097         {"cast6", RFC2440_CIPHER_CAST_6},
1098         {"aes", RFC2440_CIPHER_AES_192},
1099         {"aes", RFC2440_CIPHER_AES_256}
1100 };
1101
1102 /**
1103  * ecryptfs_code_for_cipher_string
1104  * @cipher_name: The string alias for the cipher
1105  * @key_bytes: Length of key in bytes; used for AES code selection
1106  *
1107  * Returns zero on no match, or the cipher code on match
1108  */
1109 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1110 {
1111         int i;
1112         u8 code = 0;
1113         struct ecryptfs_cipher_code_str_map_elem *map =
1114                 ecryptfs_cipher_code_str_map;
1115
1116         if (strcmp(cipher_name, "aes") == 0) {
1117                 switch (key_bytes) {
1118                 case 16:
1119                         code = RFC2440_CIPHER_AES_128;
1120                         break;
1121                 case 24:
1122                         code = RFC2440_CIPHER_AES_192;
1123                         break;
1124                 case 32:
1125                         code = RFC2440_CIPHER_AES_256;
1126                 }
1127         } else {
1128                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1129                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1130                                 code = map[i].cipher_code;
1131                                 break;
1132                         }
1133         }
1134         return code;
1135 }
1136
1137 /**
1138  * ecryptfs_cipher_code_to_string
1139  * @str: Destination to write out the cipher name
1140  * @cipher_code: The code to convert to cipher name string
1141  *
1142  * Returns zero on success
1143  */
1144 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1145 {
1146         int rc = 0;
1147         int i;
1148
1149         str[0] = '\0';
1150         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1151                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1152                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1153         if (str[0] == '\0') {
1154                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1155                                 "[%d]\n", cipher_code);
1156                 rc = -EINVAL;
1157         }
1158         return rc;
1159 }
1160
1161 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1162 {
1163         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1164         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1165         int rc;
1166
1167         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1168                                  inode);
1169         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1170                 return rc >= 0 ? -EINVAL : rc;
1171         rc = ecryptfs_validate_marker(marker);
1172         if (!rc)
1173                 ecryptfs_i_size_init(file_size, inode);
1174         return rc;
1175 }
1176
1177 void
1178 ecryptfs_write_header_metadata(char *virt,
1179                                struct ecryptfs_crypt_stat *crypt_stat,
1180                                size_t *written)
1181 {
1182         u32 header_extent_size;
1183         u16 num_header_extents_at_front;
1184
1185         header_extent_size = (u32)crypt_stat->extent_size;
1186         num_header_extents_at_front =
1187                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1188         put_unaligned_be32(header_extent_size, virt);
1189         virt += 4;
1190         put_unaligned_be16(num_header_extents_at_front, virt);
1191         (*written) = 6;
1192 }
1193
1194 struct kmem_cache *ecryptfs_header_cache;
1195
1196 /**
1197  * ecryptfs_write_headers_virt
1198  * @page_virt: The virtual address to write the headers to
1199  * @max: The size of memory allocated at page_virt
1200  * @size: Set to the number of bytes written by this function
1201  * @crypt_stat: The cryptographic context
1202  * @ecryptfs_dentry: The eCryptfs dentry
1203  *
1204  * Format version: 1
1205  *
1206  *   Header Extent:
1207  *     Octets 0-7:        Unencrypted file size (big-endian)
1208  *     Octets 8-15:       eCryptfs special marker
1209  *     Octets 16-19:      Flags
1210  *      Octet 16:         File format version number (between 0 and 255)
1211  *      Octets 17-18:     Reserved
1212  *      Octet 19:         Bit 1 (lsb): Reserved
1213  *                        Bit 2: Encrypted?
1214  *                        Bits 3-8: Reserved
1215  *     Octets 20-23:      Header extent size (big-endian)
1216  *     Octets 24-25:      Number of header extents at front of file
1217  *                        (big-endian)
1218  *     Octet  26:         Begin RFC 2440 authentication token packet set
1219  *   Data Extent 0:
1220  *     Lower data (CBC encrypted)
1221  *   Data Extent 1:
1222  *     Lower data (CBC encrypted)
1223  *   ...
1224  *
1225  * Returns zero on success
1226  */
1227 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1228                                        size_t *size,
1229                                        struct ecryptfs_crypt_stat *crypt_stat,
1230                                        struct dentry *ecryptfs_dentry)
1231 {
1232         int rc;
1233         size_t written;
1234         size_t offset;
1235
1236         offset = ECRYPTFS_FILE_SIZE_BYTES;
1237         write_ecryptfs_marker((page_virt + offset), &written);
1238         offset += written;
1239         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1240                                         &written);
1241         offset += written;
1242         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1243                                        &written);
1244         offset += written;
1245         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1246                                               ecryptfs_dentry, &written,
1247                                               max - offset);
1248         if (rc)
1249                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1250                                 "set; rc = [%d]\n", rc);
1251         if (size) {
1252                 offset += written;
1253                 *size = offset;
1254         }
1255         return rc;
1256 }
1257
1258 static int
1259 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1260                                     char *virt, size_t virt_len)
1261 {
1262         int rc;
1263
1264         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1265                                   0, virt_len);
1266         if (rc < 0)
1267                 printk(KERN_ERR "%s: Error attempting to write header "
1268                        "information to lower file; rc = [%d]\n", __func__, rc);
1269         else
1270                 rc = 0;
1271         return rc;
1272 }
1273
1274 static int
1275 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1276                                  char *page_virt, size_t size)
1277 {
1278         int rc;
1279
1280         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1281                                size, 0);
1282         return rc;
1283 }
1284
1285 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1286                                                unsigned int order)
1287 {
1288         struct page *page;
1289
1290         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1291         if (page)
1292                 return (unsigned long) page_address(page);
1293         return 0;
1294 }
1295
1296 /**
1297  * ecryptfs_write_metadata
1298  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1299  * @ecryptfs_inode: The newly created eCryptfs inode
1300  *
1301  * Write the file headers out.  This will likely involve a userspace
1302  * callout, in which the session key is encrypted with one or more
1303  * public keys and/or the passphrase necessary to do the encryption is
1304  * retrieved via a prompt.  Exactly what happens at this point should
1305  * be policy-dependent.
1306  *
1307  * Returns zero on success; non-zero on error
1308  */
1309 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1310                             struct inode *ecryptfs_inode)
1311 {
1312         struct ecryptfs_crypt_stat *crypt_stat =
1313                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1314         unsigned int order;
1315         char *virt;
1316         size_t virt_len;
1317         size_t size = 0;
1318         int rc = 0;
1319
1320         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1321                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1322                         printk(KERN_ERR "Key is invalid; bailing out\n");
1323                         rc = -EINVAL;
1324                         goto out;
1325                 }
1326         } else {
1327                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1328                        __func__);
1329                 rc = -EINVAL;
1330                 goto out;
1331         }
1332         virt_len = crypt_stat->metadata_size;
1333         order = get_order(virt_len);
1334         /* Released in this function */
1335         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1336         if (!virt) {
1337                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1338                 rc = -ENOMEM;
1339                 goto out;
1340         }
1341         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1342         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1343                                          ecryptfs_dentry);
1344         if (unlikely(rc)) {
1345                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1346                        __func__, rc);
1347                 goto out_free;
1348         }
1349         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1350                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1351                                                       size);
1352         else
1353                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1354                                                          virt_len);
1355         if (rc) {
1356                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1357                        "rc = [%d]\n", __func__, rc);
1358                 goto out_free;
1359         }
1360 out_free:
1361         free_pages((unsigned long)virt, order);
1362 out:
1363         return rc;
1364 }
1365
1366 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1367 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1368 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1369                                  char *virt, int *bytes_read,
1370                                  int validate_header_size)
1371 {
1372         int rc = 0;
1373         u32 header_extent_size;
1374         u16 num_header_extents_at_front;
1375
1376         header_extent_size = get_unaligned_be32(virt);
1377         virt += sizeof(__be32);
1378         num_header_extents_at_front = get_unaligned_be16(virt);
1379         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1380                                      * (size_t)header_extent_size));
1381         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1382         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1383             && (crypt_stat->metadata_size
1384                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1385                 rc = -EINVAL;
1386                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1387                        crypt_stat->metadata_size);
1388         }
1389         return rc;
1390 }
1391
1392 /**
1393  * set_default_header_data
1394  * @crypt_stat: The cryptographic context
1395  *
1396  * For version 0 file format; this function is only for backwards
1397  * compatibility for files created with the prior versions of
1398  * eCryptfs.
1399  */
1400 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1401 {
1402         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1403 }
1404
1405 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1406 {
1407         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1408         struct ecryptfs_crypt_stat *crypt_stat;
1409         u64 file_size;
1410
1411         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1412         mount_crypt_stat =
1413                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1414         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1415                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1416                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1417                         file_size += crypt_stat->metadata_size;
1418         } else
1419                 file_size = get_unaligned_be64(page_virt);
1420         i_size_write(inode, (loff_t)file_size);
1421         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1422 }
1423
1424 /**
1425  * ecryptfs_read_headers_virt
1426  * @page_virt: The virtual address into which to read the headers
1427  * @crypt_stat: The cryptographic context
1428  * @ecryptfs_dentry: The eCryptfs dentry
1429  * @validate_header_size: Whether to validate the header size while reading
1430  *
1431  * Read/parse the header data. The header format is detailed in the
1432  * comment block for the ecryptfs_write_headers_virt() function.
1433  *
1434  * Returns zero on success
1435  */
1436 static int ecryptfs_read_headers_virt(char *page_virt,
1437                                       struct ecryptfs_crypt_stat *crypt_stat,
1438                                       struct dentry *ecryptfs_dentry,
1439                                       int validate_header_size)
1440 {
1441         int rc = 0;
1442         int offset;
1443         int bytes_read;
1444
1445         ecryptfs_set_default_sizes(crypt_stat);
1446         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1447                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1448         offset = ECRYPTFS_FILE_SIZE_BYTES;
1449         rc = ecryptfs_validate_marker(page_virt + offset);
1450         if (rc)
1451                 goto out;
1452         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1453                 ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1454         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1455         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1456                                     &bytes_read);
1457         if (rc) {
1458                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1459                 goto out;
1460         }
1461         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1462                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1463                                 "file version [%d] is supported by this "
1464                                 "version of eCryptfs\n",
1465                                 crypt_stat->file_version,
1466                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1467                 rc = -EINVAL;
1468                 goto out;
1469         }
1470         offset += bytes_read;
1471         if (crypt_stat->file_version >= 1) {
1472                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1473                                            &bytes_read, validate_header_size);
1474                 if (rc) {
1475                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1476                                         "metadata; rc = [%d]\n", rc);
1477                 }
1478                 offset += bytes_read;
1479         } else
1480                 set_default_header_data(crypt_stat);
1481         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1482                                        ecryptfs_dentry);
1483 out:
1484         return rc;
1485 }
1486
1487 /**
1488  * ecryptfs_read_xattr_region
1489  * @page_virt: The vitual address into which to read the xattr data
1490  * @ecryptfs_inode: The eCryptfs inode
1491  *
1492  * Attempts to read the crypto metadata from the extended attribute
1493  * region of the lower file.
1494  *
1495  * Returns zero on success; non-zero on error
1496  */
1497 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1498 {
1499         struct dentry *lower_dentry =
1500                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1501         ssize_t size;
1502         int rc = 0;
1503
1504         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1505                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1506         if (size < 0) {
1507                 if (unlikely(ecryptfs_verbosity > 0))
1508                         printk(KERN_INFO "Error attempting to read the [%s] "
1509                                "xattr from the lower file; return value = "
1510                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1511                 rc = -EINVAL;
1512                 goto out;
1513         }
1514 out:
1515         return rc;
1516 }
1517
1518 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1519                                             struct inode *inode)
1520 {
1521         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1522         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1523         int rc;
1524
1525         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1526                                      ECRYPTFS_XATTR_NAME, file_size,
1527                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1528         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1529                 return rc >= 0 ? -EINVAL : rc;
1530         rc = ecryptfs_validate_marker(marker);
1531         if (!rc)
1532                 ecryptfs_i_size_init(file_size, inode);
1533         return rc;
1534 }
1535
1536 /**
1537  * ecryptfs_read_metadata
1538  *
1539  * Common entry point for reading file metadata. From here, we could
1540  * retrieve the header information from the header region of the file,
1541  * the xattr region of the file, or some other repostory that is
1542  * stored separately from the file itself. The current implementation
1543  * supports retrieving the metadata information from the file contents
1544  * and from the xattr region.
1545  *
1546  * Returns zero if valid headers found and parsed; non-zero otherwise
1547  */
1548 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1549 {
1550         int rc;
1551         char *page_virt;
1552         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1553         struct ecryptfs_crypt_stat *crypt_stat =
1554             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1555         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1556                 &ecryptfs_superblock_to_private(
1557                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1558
1559         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1560                                                       mount_crypt_stat);
1561         /* Read the first page from the underlying file */
1562         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1563         if (!page_virt) {
1564                 rc = -ENOMEM;
1565                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1566                        __func__);
1567                 goto out;
1568         }
1569         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1570                                  ecryptfs_inode);
1571         if (rc >= 0)
1572                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1573                                                 ecryptfs_dentry,
1574                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1575         if (rc) {
1576                 /* metadata is not in the file header, so try xattrs */
1577                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1578                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1579                 if (rc) {
1580                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1581                                "file header region or xattr region, inode %lu\n",
1582                                 ecryptfs_inode->i_ino);
1583                         rc = -EINVAL;
1584                         goto out;
1585                 }
1586                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1587                                                 ecryptfs_dentry,
1588                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1589                 if (rc) {
1590                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1591                                "file xattr region either, inode %lu\n",
1592                                 ecryptfs_inode->i_ino);
1593                         rc = -EINVAL;
1594                 }
1595                 if (crypt_stat->mount_crypt_stat->flags
1596                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1597                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1598                 } else {
1599                         printk(KERN_WARNING "Attempt to access file with "
1600                                "crypto metadata only in the extended attribute "
1601                                "region, but eCryptfs was mounted without "
1602                                "xattr support enabled. eCryptfs will not treat "
1603                                "this like an encrypted file, inode %lu\n",
1604                                 ecryptfs_inode->i_ino);
1605                         rc = -EINVAL;
1606                 }
1607         }
1608 out:
1609         if (page_virt) {
1610                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1611                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1612         }
1613         return rc;
1614 }
1615
1616 /**
1617  * ecryptfs_encrypt_filename - encrypt filename
1618  *
1619  * CBC-encrypts the filename. We do not want to encrypt the same
1620  * filename with the same key and IV, which may happen with hard
1621  * links, so we prepend random bits to each filename.
1622  *
1623  * Returns zero on success; non-zero otherwise
1624  */
1625 static int
1626 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1627                           struct ecryptfs_crypt_stat *crypt_stat,
1628                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1629 {
1630         int rc = 0;
1631
1632         filename->encrypted_filename = NULL;
1633         filename->encrypted_filename_size = 0;
1634         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1635             || (mount_crypt_stat && (mount_crypt_stat->flags
1636                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1637                 size_t packet_size;
1638                 size_t remaining_bytes;
1639
1640                 rc = ecryptfs_write_tag_70_packet(
1641                         NULL, NULL,
1642                         &filename->encrypted_filename_size,
1643                         mount_crypt_stat, NULL,
1644                         filename->filename_size);
1645                 if (rc) {
1646                         printk(KERN_ERR "%s: Error attempting to get packet "
1647                                "size for tag 72; rc = [%d]\n", __func__,
1648                                rc);
1649                         filename->encrypted_filename_size = 0;
1650                         goto out;
1651                 }
1652                 filename->encrypted_filename =
1653                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1654                 if (!filename->encrypted_filename) {
1655                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1656                                "to kmalloc [%zd] bytes\n", __func__,
1657                                filename->encrypted_filename_size);
1658                         rc = -ENOMEM;
1659                         goto out;
1660                 }
1661                 remaining_bytes = filename->encrypted_filename_size;
1662                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1663                                                   &remaining_bytes,
1664                                                   &packet_size,
1665                                                   mount_crypt_stat,
1666                                                   filename->filename,
1667                                                   filename->filename_size);
1668                 if (rc) {
1669                         printk(KERN_ERR "%s: Error attempting to generate "
1670                                "tag 70 packet; rc = [%d]\n", __func__,
1671                                rc);
1672                         kfree(filename->encrypted_filename);
1673                         filename->encrypted_filename = NULL;
1674                         filename->encrypted_filename_size = 0;
1675                         goto out;
1676                 }
1677                 filename->encrypted_filename_size = packet_size;
1678         } else {
1679                 printk(KERN_ERR "%s: No support for requested filename "
1680                        "encryption method in this release\n", __func__);
1681                 rc = -EOPNOTSUPP;
1682                 goto out;
1683         }
1684 out:
1685         return rc;
1686 }
1687
1688 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1689                                   const char *name, size_t name_size)
1690 {
1691         int rc = 0;
1692
1693         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1694         if (!(*copied_name)) {
1695                 rc = -ENOMEM;
1696                 goto out;
1697         }
1698         memcpy((void *)(*copied_name), (void *)name, name_size);
1699         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1700                                                  * in printing out the
1701                                                  * string in debug
1702                                                  * messages */
1703         (*copied_name_size) = name_size;
1704 out:
1705         return rc;
1706 }
1707
1708 /**
1709  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1710  * @key_tfm: Crypto context for key material, set by this function
1711  * @cipher_name: Name of the cipher
1712  * @key_size: Size of the key in bytes
1713  *
1714  * Returns zero on success. Any crypto_tfm structs allocated here
1715  * should be released by other functions, such as on a superblock put
1716  * event, regardless of whether this function succeeds for fails.
1717  */
1718 static int
1719 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1720                             char *cipher_name, size_t *key_size)
1721 {
1722         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1723         char *full_alg_name = NULL;
1724         int rc;
1725
1726         *key_tfm = NULL;
1727         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1728                 rc = -EINVAL;
1729                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1730                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1731                 goto out;
1732         }
1733         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1734                                                     "ecb");
1735         if (rc)
1736                 goto out;
1737         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1738         if (IS_ERR(*key_tfm)) {
1739                 rc = PTR_ERR(*key_tfm);
1740                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1741                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1742                 goto out;
1743         }
1744         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1745         if (*key_size == 0) {
1746                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1747
1748                 *key_size = alg->max_keysize;
1749         }
1750         get_random_bytes(dummy_key, *key_size);
1751         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1752         if (rc) {
1753                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1754                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1755                        rc);
1756                 rc = -EINVAL;
1757                 goto out;
1758         }
1759 out:
1760         kfree(full_alg_name);
1761         return rc;
1762 }
1763
1764 struct kmem_cache *ecryptfs_key_tfm_cache;
1765 static struct list_head key_tfm_list;
1766 struct mutex key_tfm_list_mutex;
1767
1768 int __init ecryptfs_init_crypto(void)
1769 {
1770         mutex_init(&key_tfm_list_mutex);
1771         INIT_LIST_HEAD(&key_tfm_list);
1772         return 0;
1773 }
1774
1775 /**
1776  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1777  *
1778  * Called only at module unload time
1779  */
1780 int ecryptfs_destroy_crypto(void)
1781 {
1782         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1783
1784         mutex_lock(&key_tfm_list_mutex);
1785         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1786                                  key_tfm_list) {
1787                 list_del(&key_tfm->key_tfm_list);
1788                 if (key_tfm->key_tfm)
1789                         crypto_free_blkcipher(key_tfm->key_tfm);
1790                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1791         }
1792         mutex_unlock(&key_tfm_list_mutex);
1793         return 0;
1794 }
1795
1796 int
1797 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1798                          size_t key_size)
1799 {
1800         struct ecryptfs_key_tfm *tmp_tfm;
1801         int rc = 0;
1802
1803         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1804
1805         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1806         if (key_tfm != NULL)
1807                 (*key_tfm) = tmp_tfm;
1808         if (!tmp_tfm) {
1809                 rc = -ENOMEM;
1810                 printk(KERN_ERR "Error attempting to allocate from "
1811                        "ecryptfs_key_tfm_cache\n");
1812                 goto out;
1813         }
1814         mutex_init(&tmp_tfm->key_tfm_mutex);
1815         strncpy(tmp_tfm->cipher_name, cipher_name,
1816                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1817         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1818         tmp_tfm->key_size = key_size;
1819         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1820                                          tmp_tfm->cipher_name,
1821                                          &tmp_tfm->key_size);
1822         if (rc) {
1823                 printk(KERN_ERR "Error attempting to initialize key TFM "
1824                        "cipher with name = [%s]; rc = [%d]\n",
1825                        tmp_tfm->cipher_name, rc);
1826                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1827                 if (key_tfm != NULL)
1828                         (*key_tfm) = NULL;
1829                 goto out;
1830         }
1831         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1832 out:
1833         return rc;
1834 }
1835
1836 /**
1837  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1838  * @cipher_name: the name of the cipher to search for
1839  * @key_tfm: set to corresponding tfm if found
1840  *
1841  * Searches for cached key_tfm matching @cipher_name
1842  * Must be called with &key_tfm_list_mutex held
1843  * Returns 1 if found, with @key_tfm set
1844  * Returns 0 if not found, with @key_tfm set to NULL
1845  */
1846 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1847 {
1848         struct ecryptfs_key_tfm *tmp_key_tfm;
1849
1850         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1851
1852         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1853                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1854                         if (key_tfm)
1855                                 (*key_tfm) = tmp_key_tfm;
1856                         return 1;
1857                 }
1858         }
1859         if (key_tfm)
1860                 (*key_tfm) = NULL;
1861         return 0;
1862 }
1863
1864 /**
1865  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1866  *
1867  * @tfm: set to cached tfm found, or new tfm created
1868  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1869  * @cipher_name: the name of the cipher to search for and/or add
1870  *
1871  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1872  * Searches for cached item first, and creates new if not found.
1873  * Returns 0 on success, non-zero if adding new cipher failed
1874  */
1875 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1876                                                struct mutex **tfm_mutex,
1877                                                char *cipher_name)
1878 {
1879         struct ecryptfs_key_tfm *key_tfm;
1880         int rc = 0;
1881
1882         (*tfm) = NULL;
1883         (*tfm_mutex) = NULL;
1884
1885         mutex_lock(&key_tfm_list_mutex);
1886         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1887                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1888                 if (rc) {
1889                         printk(KERN_ERR "Error adding new key_tfm to list; "
1890                                         "rc = [%d]\n", rc);
1891                         goto out;
1892                 }
1893         }
1894         (*tfm) = key_tfm->key_tfm;
1895         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1896 out:
1897         mutex_unlock(&key_tfm_list_mutex);
1898         return rc;
1899 }
1900
1901 /* 64 characters forming a 6-bit target field */
1902 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1903                                                  "EFGHIJKLMNOPQRST"
1904                                                  "UVWXYZabcdefghij"
1905                                                  "klmnopqrstuvwxyz");
1906
1907 /* We could either offset on every reverse map or just pad some 0x00's
1908  * at the front here */
1909 static const unsigned char filename_rev_map[256] = {
1910         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1911         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1912         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1913         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1914         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1915         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1916         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1917         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1918         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1919         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1920         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1921         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1922         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1923         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1924         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1925         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1926 };
1927
1928 /**
1929  * ecryptfs_encode_for_filename
1930  * @dst: Destination location for encoded filename
1931  * @dst_size: Size of the encoded filename in bytes
1932  * @src: Source location for the filename to encode
1933  * @src_size: Size of the source in bytes
1934  */
1935 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1936                                   unsigned char *src, size_t src_size)
1937 {
1938         size_t num_blocks;
1939         size_t block_num = 0;
1940         size_t dst_offset = 0;
1941         unsigned char last_block[3];
1942
1943         if (src_size == 0) {
1944                 (*dst_size) = 0;
1945                 goto out;
1946         }
1947         num_blocks = (src_size / 3);
1948         if ((src_size % 3) == 0) {
1949                 memcpy(last_block, (&src[src_size - 3]), 3);
1950         } else {
1951                 num_blocks++;
1952                 last_block[2] = 0x00;
1953                 switch (src_size % 3) {
1954                 case 1:
1955                         last_block[0] = src[src_size - 1];
1956                         last_block[1] = 0x00;
1957                         break;
1958                 case 2:
1959                         last_block[0] = src[src_size - 2];
1960                         last_block[1] = src[src_size - 1];
1961                 }
1962         }
1963         (*dst_size) = (num_blocks * 4);
1964         if (!dst)
1965                 goto out;
1966         while (block_num < num_blocks) {
1967                 unsigned char *src_block;
1968                 unsigned char dst_block[4];
1969
1970                 if (block_num == (num_blocks - 1))
1971                         src_block = last_block;
1972                 else
1973                         src_block = &src[block_num * 3];
1974                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1975                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1976                                 | ((src_block[1] >> 4) & 0x0F));
1977                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1978                                 | ((src_block[2] >> 6) & 0x03));
1979                 dst_block[3] = (src_block[2] & 0x3F);
1980                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1981                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1982                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1983                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1984                 block_num++;
1985         }
1986 out:
1987         return;
1988 }
1989
1990 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1991 {
1992         /* Not exact; conservatively long. Every block of 4
1993          * encoded characters decodes into a block of 3
1994          * decoded characters. This segment of code provides
1995          * the caller with the maximum amount of allocated
1996          * space that @dst will need to point to in a
1997          * subsequent call. */
1998         return ((encoded_size + 1) * 3) / 4;
1999 }
2000
2001 /**
2002  * ecryptfs_decode_from_filename
2003  * @dst: If NULL, this function only sets @dst_size and returns. If
2004  *       non-NULL, this function decodes the encoded octets in @src
2005  *       into the memory that @dst points to.
2006  * @dst_size: Set to the size of the decoded string.
2007  * @src: The encoded set of octets to decode.
2008  * @src_size: The size of the encoded set of octets to decode.
2009  */
2010 static void
2011 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2012                               const unsigned char *src, size_t src_size)
2013 {
2014         u8 current_bit_offset = 0;
2015         size_t src_byte_offset = 0;
2016         size_t dst_byte_offset = 0;
2017
2018         if (dst == NULL) {
2019                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
2020                 goto out;
2021         }
2022         while (src_byte_offset < src_size) {
2023                 unsigned char src_byte =
2024                                 filename_rev_map[(int)src[src_byte_offset]];
2025
2026                 switch (current_bit_offset) {
2027                 case 0:
2028                         dst[dst_byte_offset] = (src_byte << 2);
2029                         current_bit_offset = 6;
2030                         break;
2031                 case 6:
2032                         dst[dst_byte_offset++] |= (src_byte >> 4);
2033                         dst[dst_byte_offset] = ((src_byte & 0xF)
2034                                                  << 4);
2035                         current_bit_offset = 4;
2036                         break;
2037                 case 4:
2038                         dst[dst_byte_offset++] |= (src_byte >> 2);
2039                         dst[dst_byte_offset] = (src_byte << 6);
2040                         current_bit_offset = 2;
2041                         break;
2042                 case 2:
2043                         dst[dst_byte_offset++] |= (src_byte);
2044                         dst[dst_byte_offset] = 0;
2045                         current_bit_offset = 0;
2046                         break;
2047                 }
2048                 src_byte_offset++;
2049         }
2050         (*dst_size) = dst_byte_offset;
2051 out:
2052         return;
2053 }
2054
2055 /**
2056  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2057  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2058  * @name: The plaintext name
2059  * @length: The length of the plaintext
2060  * @encoded_name: The encypted name
2061  *
2062  * Encrypts and encodes a filename into something that constitutes a
2063  * valid filename for a filesystem, with printable characters.
2064  *
2065  * We assume that we have a properly initialized crypto context,
2066  * pointed to by crypt_stat->tfm.
2067  *
2068  * Returns zero on success; non-zero on otherwise
2069  */
2070 int ecryptfs_encrypt_and_encode_filename(
2071         char **encoded_name,
2072         size_t *encoded_name_size,
2073         struct ecryptfs_crypt_stat *crypt_stat,
2074         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2075         const char *name, size_t name_size)
2076 {
2077         size_t encoded_name_no_prefix_size;
2078         int rc = 0;
2079
2080         (*encoded_name) = NULL;
2081         (*encoded_name_size) = 0;
2082         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2083             || (mount_crypt_stat && (mount_crypt_stat->flags
2084                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2085                 struct ecryptfs_filename *filename;
2086
2087                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2088                 if (!filename) {
2089                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2090                                "to kzalloc [%zd] bytes\n", __func__,
2091                                sizeof(*filename));
2092                         rc = -ENOMEM;
2093                         goto out;
2094                 }
2095                 filename->filename = (char *)name;
2096                 filename->filename_size = name_size;
2097                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2098                                                mount_crypt_stat);
2099                 if (rc) {
2100                         printk(KERN_ERR "%s: Error attempting to encrypt "
2101                                "filename; rc = [%d]\n", __func__, rc);
2102                         kfree(filename);
2103                         goto out;
2104                 }
2105                 ecryptfs_encode_for_filename(
2106                         NULL, &encoded_name_no_prefix_size,
2107                         filename->encrypted_filename,
2108                         filename->encrypted_filename_size);
2109                 if ((crypt_stat && (crypt_stat->flags
2110                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2111                     || (mount_crypt_stat
2112                         && (mount_crypt_stat->flags
2113                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2114                         (*encoded_name_size) =
2115                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2116                                  + encoded_name_no_prefix_size);
2117                 else
2118                         (*encoded_name_size) =
2119                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2120                                  + encoded_name_no_prefix_size);
2121                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2122                 if (!(*encoded_name)) {
2123                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2124                                "to kzalloc [%zd] bytes\n", __func__,
2125                                (*encoded_name_size));
2126                         rc = -ENOMEM;
2127                         kfree(filename->encrypted_filename);
2128                         kfree(filename);
2129                         goto out;
2130                 }
2131                 if ((crypt_stat && (crypt_stat->flags
2132                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2133                     || (mount_crypt_stat
2134                         && (mount_crypt_stat->flags
2135                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2136                         memcpy((*encoded_name),
2137                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2138                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2139                         ecryptfs_encode_for_filename(
2140                             ((*encoded_name)
2141                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2142                             &encoded_name_no_prefix_size,
2143                             filename->encrypted_filename,
2144                             filename->encrypted_filename_size);
2145                         (*encoded_name_size) =
2146                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2147                                  + encoded_name_no_prefix_size);
2148                         (*encoded_name)[(*encoded_name_size)] = '\0';
2149                 } else {
2150                         rc = -EOPNOTSUPP;
2151                 }
2152                 if (rc) {
2153                         printk(KERN_ERR "%s: Error attempting to encode "
2154                                "encrypted filename; rc = [%d]\n", __func__,
2155                                rc);
2156                         kfree((*encoded_name));
2157                         (*encoded_name) = NULL;
2158                         (*encoded_name_size) = 0;
2159                 }
2160                 kfree(filename->encrypted_filename);
2161                 kfree(filename);
2162         } else {
2163                 rc = ecryptfs_copy_filename(encoded_name,
2164                                             encoded_name_size,
2165                                             name, name_size);
2166         }
2167 out:
2168         return rc;
2169 }
2170
2171 /**
2172  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2173  * @plaintext_name: The plaintext name
2174  * @plaintext_name_size: The plaintext name size
2175  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2176  * @name: The filename in cipher text
2177  * @name_size: The cipher text name size
2178  *
2179  * Decrypts and decodes the filename.
2180  *
2181  * Returns zero on error; non-zero otherwise
2182  */
2183 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2184                                          size_t *plaintext_name_size,
2185                                          struct dentry *ecryptfs_dir_dentry,
2186                                          const char *name, size_t name_size)
2187 {
2188         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2189                 &ecryptfs_superblock_to_private(
2190                         ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2191         char *decoded_name;
2192         size_t decoded_name_size;
2193         size_t packet_size;
2194         int rc = 0;
2195
2196         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2197             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2198             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2199             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2200                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2201                 const char *orig_name = name;
2202                 size_t orig_name_size = name_size;
2203
2204                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2205                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2206                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2207                                               name, name_size);
2208                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2209                 if (!decoded_name) {
2210                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2211                                "to kmalloc [%zd] bytes\n", __func__,
2212                                decoded_name_size);
2213                         rc = -ENOMEM;
2214                         goto out;
2215                 }
2216                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2217                                               name, name_size);
2218                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2219                                                   plaintext_name_size,
2220                                                   &packet_size,
2221                                                   mount_crypt_stat,
2222                                                   decoded_name,
2223                                                   decoded_name_size);
2224                 if (rc) {
2225                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2226                                "from filename; copying through filename "
2227                                "as-is\n", __func__);
2228                         rc = ecryptfs_copy_filename(plaintext_name,
2229                                                     plaintext_name_size,
2230                                                     orig_name, orig_name_size);
2231                         goto out_free;
2232                 }
2233         } else {
2234                 rc = ecryptfs_copy_filename(plaintext_name,
2235                                             plaintext_name_size,
2236                                             name, name_size);
2237                 goto out;
2238         }
2239 out_free:
2240         kfree(decoded_name);
2241 out:
2242         return rc;
2243 }
2244
2245 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2246
2247 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2248                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2249 {
2250         struct blkcipher_desc desc;
2251         struct mutex *tfm_mutex;
2252         size_t cipher_blocksize;
2253         int rc;
2254
2255         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2256                 (*namelen) = lower_namelen;
2257                 return 0;
2258         }
2259
2260         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2261                         mount_crypt_stat->global_default_fn_cipher_name);
2262         if (unlikely(rc)) {
2263                 (*namelen) = 0;
2264                 return rc;
2265         }
2266
2267         mutex_lock(tfm_mutex);
2268         cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2269         mutex_unlock(tfm_mutex);
2270
2271         /* Return an exact amount for the common cases */
2272         if (lower_namelen == NAME_MAX
2273             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2274                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2275                 return 0;
2276         }
2277
2278         /* Return a safe estimate for the uncommon cases */
2279         (*namelen) = lower_namelen;
2280         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2281         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2282         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2283         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2284         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2285         /* Worst case is that the filename is padded nearly a full block size */
2286         (*namelen) -= cipher_blocksize - 1;
2287
2288         if ((*namelen) < 0)
2289                 (*namelen) = 0;
2290
2291         return 0;
2292 }