CIFS: Fix too big maxBuf size for SMB3 mounts
[linux-3.10.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_ablkcipher(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 struct extent_crypt_result {
323         struct completion completion;
324         int rc;
325 };
326
327 static void extent_crypt_complete(struct crypto_async_request *req, int rc)
328 {
329         struct extent_crypt_result *ecr = req->data;
330
331         if (rc == -EINPROGRESS)
332                 return;
333
334         ecr->rc = rc;
335         complete(&ecr->completion);
336 }
337
338 /**
339  * encrypt_scatterlist
340  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
341  * @dest_sg: Destination of encrypted data
342  * @src_sg: Data to be encrypted
343  * @size: Length of data to be encrypted
344  * @iv: iv to use during encryption
345  *
346  * Returns the number of bytes encrypted; negative value on error
347  */
348 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
349                                struct scatterlist *dest_sg,
350                                struct scatterlist *src_sg, int size,
351                                unsigned char *iv)
352 {
353         struct ablkcipher_request *req = NULL;
354         struct extent_crypt_result ecr;
355         int rc = 0;
356
357         BUG_ON(!crypt_stat || !crypt_stat->tfm
358                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
359         if (unlikely(ecryptfs_verbosity > 0)) {
360                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
361                                 crypt_stat->key_size);
362                 ecryptfs_dump_hex(crypt_stat->key,
363                                   crypt_stat->key_size);
364         }
365
366         init_completion(&ecr.completion);
367
368         mutex_lock(&crypt_stat->cs_tfm_mutex);
369         req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
370         if (!req) {
371                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
372                 rc = -ENOMEM;
373                 goto out;
374         }
375
376         ablkcipher_request_set_callback(req,
377                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
378                         extent_crypt_complete, &ecr);
379         /* Consider doing this once, when the file is opened */
380         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
381                 rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
382                                               crypt_stat->key_size);
383                 if (rc) {
384                         ecryptfs_printk(KERN_ERR,
385                                         "Error setting key; rc = [%d]\n",
386                                         rc);
387                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
388                         rc = -EINVAL;
389                         goto out;
390                 }
391                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
392         }
393         mutex_unlock(&crypt_stat->cs_tfm_mutex);
394         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
395         ablkcipher_request_set_crypt(req, src_sg, dest_sg, size, iv);
396         rc = crypto_ablkcipher_encrypt(req);
397         if (rc == -EINPROGRESS || rc == -EBUSY) {
398                 struct extent_crypt_result *ecr = req->base.data;
399
400                 wait_for_completion(&ecr->completion);
401                 rc = ecr->rc;
402                 INIT_COMPLETION(ecr->completion);
403         }
404 out:
405         ablkcipher_request_free(req);
406         return rc;
407 }
408
409 /**
410  * ecryptfs_lower_offset_for_extent
411  *
412  * Convert an eCryptfs page index into a lower byte offset
413  */
414 static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
415                                              struct ecryptfs_crypt_stat *crypt_stat)
416 {
417         (*offset) = ecryptfs_lower_header_size(crypt_stat)
418                     + (crypt_stat->extent_size * extent_num);
419 }
420
421 /**
422  * ecryptfs_encrypt_extent
423  * @enc_extent_page: Allocated page into which to encrypt the data in
424  *                   @page
425  * @crypt_stat: crypt_stat containing cryptographic context for the
426  *              encryption operation
427  * @page: Page containing plaintext data extent to encrypt
428  * @extent_offset: Page extent offset for use in generating IV
429  *
430  * Encrypts one extent of data.
431  *
432  * Return zero on success; non-zero otherwise
433  */
434 static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
435                                    struct ecryptfs_crypt_stat *crypt_stat,
436                                    struct page *page,
437                                    unsigned long extent_offset)
438 {
439         loff_t extent_base;
440         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
441         int rc;
442
443         extent_base = (((loff_t)page->index)
444                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
445         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
446                                 (extent_base + extent_offset));
447         if (rc) {
448                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
449                         "extent [0x%.16llx]; rc = [%d]\n",
450                         (unsigned long long)(extent_base + extent_offset), rc);
451                 goto out;
452         }
453         rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
454                                           page, (extent_offset
455                                                  * crypt_stat->extent_size),
456                                           crypt_stat->extent_size, extent_iv);
457         if (rc < 0) {
458                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
459                        "page->index = [%ld], extent_offset = [%ld]; "
460                        "rc = [%d]\n", __func__, page->index, extent_offset,
461                        rc);
462                 goto out;
463         }
464         rc = 0;
465 out:
466         return rc;
467 }
468
469 /**
470  * ecryptfs_encrypt_page
471  * @page: Page mapped from the eCryptfs inode for the file; contains
472  *        decrypted content that needs to be encrypted (to a temporary
473  *        page; not in place) and written out to the lower file
474  *
475  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
476  * that eCryptfs pages may straddle the lower pages -- for instance,
477  * if the file was created on a machine with an 8K page size
478  * (resulting in an 8K header), and then the file is copied onto a
479  * host with a 32K page size, then when reading page 0 of the eCryptfs
480  * file, 24K of page 0 of the lower file will be read and decrypted,
481  * and then 8K of page 1 of the lower file will be read and decrypted.
482  *
483  * Returns zero on success; negative on error
484  */
485 int ecryptfs_encrypt_page(struct page *page)
486 {
487         struct inode *ecryptfs_inode;
488         struct ecryptfs_crypt_stat *crypt_stat;
489         char *enc_extent_virt;
490         struct page *enc_extent_page = NULL;
491         loff_t extent_offset;
492         int rc = 0;
493
494         ecryptfs_inode = page->mapping->host;
495         crypt_stat =
496                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
497         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
498         enc_extent_page = alloc_page(GFP_USER);
499         if (!enc_extent_page) {
500                 rc = -ENOMEM;
501                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
502                                 "encrypted extent\n");
503                 goto out;
504         }
505         enc_extent_virt = kmap(enc_extent_page);
506         for (extent_offset = 0;
507              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
508              extent_offset++) {
509                 loff_t offset;
510
511                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
512                                              extent_offset);
513                 if (rc) {
514                         printk(KERN_ERR "%s: Error encrypting extent; "
515                                "rc = [%d]\n", __func__, rc);
516                         goto out;
517                 }
518                 ecryptfs_lower_offset_for_extent(
519                         &offset, ((((loff_t)page->index)
520                                    * (PAGE_CACHE_SIZE
521                                       / crypt_stat->extent_size))
522                                   + extent_offset), crypt_stat);
523                 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
524                                           offset, crypt_stat->extent_size);
525                 if (rc < 0) {
526                         ecryptfs_printk(KERN_ERR, "Error attempting "
527                                         "to write lower page; rc = [%d]"
528                                         "\n", rc);
529                         goto out;
530                 }
531         }
532         rc = 0;
533 out:
534         if (enc_extent_page) {
535                 kunmap(enc_extent_page);
536                 __free_page(enc_extent_page);
537         }
538         return rc;
539 }
540
541 static int ecryptfs_decrypt_extent(struct page *page,
542                                    struct ecryptfs_crypt_stat *crypt_stat,
543                                    struct page *enc_extent_page,
544                                    unsigned long extent_offset)
545 {
546         loff_t extent_base;
547         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
548         int rc;
549
550         extent_base = (((loff_t)page->index)
551                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
552         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
553                                 (extent_base + extent_offset));
554         if (rc) {
555                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
556                         "extent [0x%.16llx]; rc = [%d]\n",
557                         (unsigned long long)(extent_base + extent_offset), rc);
558                 goto out;
559         }
560         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
561                                           (extent_offset
562                                            * crypt_stat->extent_size),
563                                           enc_extent_page, 0,
564                                           crypt_stat->extent_size, extent_iv);
565         if (rc < 0) {
566                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
567                        "page->index = [%ld], extent_offset = [%ld]; "
568                        "rc = [%d]\n", __func__, page->index, extent_offset,
569                        rc);
570                 goto out;
571         }
572         rc = 0;
573 out:
574         return rc;
575 }
576
577 /**
578  * ecryptfs_decrypt_page
579  * @page: Page mapped from the eCryptfs inode for the file; data read
580  *        and decrypted from the lower file will be written into this
581  *        page
582  *
583  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
584  * that eCryptfs pages may straddle the lower pages -- for instance,
585  * if the file was created on a machine with an 8K page size
586  * (resulting in an 8K header), and then the file is copied onto a
587  * host with a 32K page size, then when reading page 0 of the eCryptfs
588  * file, 24K of page 0 of the lower file will be read and decrypted,
589  * and then 8K of page 1 of the lower file will be read and decrypted.
590  *
591  * Returns zero on success; negative on error
592  */
593 int ecryptfs_decrypt_page(struct page *page)
594 {
595         struct inode *ecryptfs_inode;
596         struct ecryptfs_crypt_stat *crypt_stat;
597         char *enc_extent_virt;
598         struct page *enc_extent_page = NULL;
599         unsigned long extent_offset;
600         int rc = 0;
601
602         ecryptfs_inode = page->mapping->host;
603         crypt_stat =
604                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
605         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
606         enc_extent_page = alloc_page(GFP_USER);
607         if (!enc_extent_page) {
608                 rc = -ENOMEM;
609                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
610                                 "encrypted extent\n");
611                 goto out;
612         }
613         enc_extent_virt = kmap(enc_extent_page);
614         for (extent_offset = 0;
615              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
616              extent_offset++) {
617                 loff_t offset;
618
619                 ecryptfs_lower_offset_for_extent(
620                         &offset, ((page->index * (PAGE_CACHE_SIZE
621                                                   / crypt_stat->extent_size))
622                                   + extent_offset), crypt_stat);
623                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
624                                          crypt_stat->extent_size,
625                                          ecryptfs_inode);
626                 if (rc < 0) {
627                         ecryptfs_printk(KERN_ERR, "Error attempting "
628                                         "to read lower page; rc = [%d]"
629                                         "\n", rc);
630                         goto out;
631                 }
632                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
633                                              extent_offset);
634                 if (rc) {
635                         printk(KERN_ERR "%s: Error encrypting extent; "
636                                "rc = [%d]\n", __func__, rc);
637                         goto out;
638                 }
639         }
640 out:
641         if (enc_extent_page) {
642                 kunmap(enc_extent_page);
643                 __free_page(enc_extent_page);
644         }
645         return rc;
646 }
647
648 /**
649  * decrypt_scatterlist
650  * @crypt_stat: Cryptographic context
651  * @dest_sg: The destination scatterlist to decrypt into
652  * @src_sg: The source scatterlist to decrypt from
653  * @size: The number of bytes to decrypt
654  * @iv: The initialization vector to use for the decryption
655  *
656  * Returns the number of bytes decrypted; negative value on error
657  */
658 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
659                                struct scatterlist *dest_sg,
660                                struct scatterlist *src_sg, int size,
661                                unsigned char *iv)
662 {
663         struct ablkcipher_request *req = NULL;
664         struct extent_crypt_result ecr;
665         int rc = 0;
666
667         BUG_ON(!crypt_stat || !crypt_stat->tfm
668                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
669         if (unlikely(ecryptfs_verbosity > 0)) {
670                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
671                                 crypt_stat->key_size);
672                 ecryptfs_dump_hex(crypt_stat->key,
673                                   crypt_stat->key_size);
674         }
675
676         init_completion(&ecr.completion);
677
678         mutex_lock(&crypt_stat->cs_tfm_mutex);
679         req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
680         if (!req) {
681                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
682                 rc = -ENOMEM;
683                 goto out;
684         }
685
686         ablkcipher_request_set_callback(req,
687                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
688                         extent_crypt_complete, &ecr);
689         /* Consider doing this once, when the file is opened */
690         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
691                 rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
692                                               crypt_stat->key_size);
693                 if (rc) {
694                         ecryptfs_printk(KERN_ERR,
695                                         "Error setting key; rc = [%d]\n",
696                                         rc);
697                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
698                         rc = -EINVAL;
699                         goto out;
700                 }
701                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
702         }
703         mutex_unlock(&crypt_stat->cs_tfm_mutex);
704         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
705         ablkcipher_request_set_crypt(req, src_sg, dest_sg, size, iv);
706         rc = crypto_ablkcipher_decrypt(req);
707         if (rc == -EINPROGRESS || rc == -EBUSY) {
708                 struct extent_crypt_result *ecr = req->base.data;
709
710                 wait_for_completion(&ecr->completion);
711                 rc = ecr->rc;
712                 INIT_COMPLETION(ecr->completion);
713         }
714 out:
715         ablkcipher_request_free(req);
716         return rc;
717
718 }
719
720 /**
721  * ecryptfs_encrypt_page_offset
722  * @crypt_stat: The cryptographic context
723  * @dst_page: The page to encrypt into
724  * @dst_offset: The offset in the page to encrypt into
725  * @src_page: The page to encrypt from
726  * @src_offset: The offset in the page to encrypt from
727  * @size: The number of bytes to encrypt
728  * @iv: The initialization vector to use for the encryption
729  *
730  * Returns the number of bytes encrypted
731  */
732 static int
733 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
734                              struct page *dst_page, int dst_offset,
735                              struct page *src_page, int src_offset, int size,
736                              unsigned char *iv)
737 {
738         struct scatterlist src_sg, dst_sg;
739
740         sg_init_table(&src_sg, 1);
741         sg_init_table(&dst_sg, 1);
742
743         sg_set_page(&src_sg, src_page, size, src_offset);
744         sg_set_page(&dst_sg, dst_page, size, dst_offset);
745         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
746 }
747
748 /**
749  * ecryptfs_decrypt_page_offset
750  * @crypt_stat: The cryptographic context
751  * @dst_page: The page to decrypt into
752  * @dst_offset: The offset in the page to decrypt into
753  * @src_page: The page to decrypt from
754  * @src_offset: The offset in the page to decrypt from
755  * @size: The number of bytes to decrypt
756  * @iv: The initialization vector to use for the decryption
757  *
758  * Returns the number of bytes decrypted
759  */
760 static int
761 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
762                              struct page *dst_page, int dst_offset,
763                              struct page *src_page, int src_offset, int size,
764                              unsigned char *iv)
765 {
766         struct scatterlist src_sg, dst_sg;
767
768         sg_init_table(&src_sg, 1);
769         sg_set_page(&src_sg, src_page, size, src_offset);
770
771         sg_init_table(&dst_sg, 1);
772         sg_set_page(&dst_sg, dst_page, size, dst_offset);
773
774         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
775 }
776
777 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
778
779 /**
780  * ecryptfs_init_crypt_ctx
781  * @crypt_stat: Uninitialized crypt stats structure
782  *
783  * Initialize the crypto context.
784  *
785  * TODO: Performance: Keep a cache of initialized cipher contexts;
786  * only init if needed
787  */
788 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
789 {
790         char *full_alg_name;
791         int rc = -EINVAL;
792
793         if (!crypt_stat->cipher) {
794                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
795                 goto out;
796         }
797         ecryptfs_printk(KERN_DEBUG,
798                         "Initializing cipher [%s]; strlen = [%d]; "
799                         "key_size_bits = [%zd]\n",
800                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
801                         crypt_stat->key_size << 3);
802         if (crypt_stat->tfm) {
803                 rc = 0;
804                 goto out;
805         }
806         mutex_lock(&crypt_stat->cs_tfm_mutex);
807         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
808                                                     crypt_stat->cipher, "cbc");
809         if (rc)
810                 goto out_unlock;
811         crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
812         kfree(full_alg_name);
813         if (IS_ERR(crypt_stat->tfm)) {
814                 rc = PTR_ERR(crypt_stat->tfm);
815                 crypt_stat->tfm = NULL;
816                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
817                                 "Error initializing cipher [%s]\n",
818                                 crypt_stat->cipher);
819                 goto out_unlock;
820         }
821         crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
822         rc = 0;
823 out_unlock:
824         mutex_unlock(&crypt_stat->cs_tfm_mutex);
825 out:
826         return rc;
827 }
828
829 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
830 {
831         int extent_size_tmp;
832
833         crypt_stat->extent_mask = 0xFFFFFFFF;
834         crypt_stat->extent_shift = 0;
835         if (crypt_stat->extent_size == 0)
836                 return;
837         extent_size_tmp = crypt_stat->extent_size;
838         while ((extent_size_tmp & 0x01) == 0) {
839                 extent_size_tmp >>= 1;
840                 crypt_stat->extent_mask <<= 1;
841                 crypt_stat->extent_shift++;
842         }
843 }
844
845 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
846 {
847         /* Default values; may be overwritten as we are parsing the
848          * packets. */
849         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
850         set_extent_mask_and_shift(crypt_stat);
851         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
852         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
853                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
854         else {
855                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
856                         crypt_stat->metadata_size =
857                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
858                 else
859                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
860         }
861 }
862
863 /**
864  * ecryptfs_compute_root_iv
865  * @crypt_stats
866  *
867  * On error, sets the root IV to all 0's.
868  */
869 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
870 {
871         int rc = 0;
872         char dst[MD5_DIGEST_SIZE];
873
874         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
875         BUG_ON(crypt_stat->iv_bytes <= 0);
876         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
877                 rc = -EINVAL;
878                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
879                                 "cannot generate root IV\n");
880                 goto out;
881         }
882         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
883                                     crypt_stat->key_size);
884         if (rc) {
885                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
886                                 "MD5 while generating root IV\n");
887                 goto out;
888         }
889         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
890 out:
891         if (rc) {
892                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
893                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
894         }
895         return rc;
896 }
897
898 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
899 {
900         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
901         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
902         ecryptfs_compute_root_iv(crypt_stat);
903         if (unlikely(ecryptfs_verbosity > 0)) {
904                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
905                 ecryptfs_dump_hex(crypt_stat->key,
906                                   crypt_stat->key_size);
907         }
908 }
909
910 /**
911  * ecryptfs_copy_mount_wide_flags_to_inode_flags
912  * @crypt_stat: The inode's cryptographic context
913  * @mount_crypt_stat: The mount point's cryptographic context
914  *
915  * This function propagates the mount-wide flags to individual inode
916  * flags.
917  */
918 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
919         struct ecryptfs_crypt_stat *crypt_stat,
920         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
921 {
922         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
923                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
924         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
925                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
926         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
927                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
928                 if (mount_crypt_stat->flags
929                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
930                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
931                 else if (mount_crypt_stat->flags
932                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
933                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
934         }
935 }
936
937 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
938         struct ecryptfs_crypt_stat *crypt_stat,
939         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
940 {
941         struct ecryptfs_global_auth_tok *global_auth_tok;
942         int rc = 0;
943
944         mutex_lock(&crypt_stat->keysig_list_mutex);
945         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
946
947         list_for_each_entry(global_auth_tok,
948                             &mount_crypt_stat->global_auth_tok_list,
949                             mount_crypt_stat_list) {
950                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
951                         continue;
952                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
953                 if (rc) {
954                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
955                         goto out;
956                 }
957         }
958
959 out:
960         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
961         mutex_unlock(&crypt_stat->keysig_list_mutex);
962         return rc;
963 }
964
965 /**
966  * ecryptfs_set_default_crypt_stat_vals
967  * @crypt_stat: The inode's cryptographic context
968  * @mount_crypt_stat: The mount point's cryptographic context
969  *
970  * Default values in the event that policy does not override them.
971  */
972 static void ecryptfs_set_default_crypt_stat_vals(
973         struct ecryptfs_crypt_stat *crypt_stat,
974         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
975 {
976         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
977                                                       mount_crypt_stat);
978         ecryptfs_set_default_sizes(crypt_stat);
979         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
980         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
981         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
982         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
983         crypt_stat->mount_crypt_stat = mount_crypt_stat;
984 }
985
986 /**
987  * ecryptfs_new_file_context
988  * @ecryptfs_inode: The eCryptfs inode
989  *
990  * If the crypto context for the file has not yet been established,
991  * this is where we do that.  Establishing a new crypto context
992  * involves the following decisions:
993  *  - What cipher to use?
994  *  - What set of authentication tokens to use?
995  * Here we just worry about getting enough information into the
996  * authentication tokens so that we know that they are available.
997  * We associate the available authentication tokens with the new file
998  * via the set of signatures in the crypt_stat struct.  Later, when
999  * the headers are actually written out, we may again defer to
1000  * userspace to perform the encryption of the session key; for the
1001  * foreseeable future, this will be the case with public key packets.
1002  *
1003  * Returns zero on success; non-zero otherwise
1004  */
1005 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
1006 {
1007         struct ecryptfs_crypt_stat *crypt_stat =
1008             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1009         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1010             &ecryptfs_superblock_to_private(
1011                     ecryptfs_inode->i_sb)->mount_crypt_stat;
1012         int cipher_name_len;
1013         int rc = 0;
1014
1015         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
1016         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1017         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1018                                                       mount_crypt_stat);
1019         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1020                                                          mount_crypt_stat);
1021         if (rc) {
1022                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1023                        "to the inode key sigs; rc = [%d]\n", rc);
1024                 goto out;
1025         }
1026         cipher_name_len =
1027                 strlen(mount_crypt_stat->global_default_cipher_name);
1028         memcpy(crypt_stat->cipher,
1029                mount_crypt_stat->global_default_cipher_name,
1030                cipher_name_len);
1031         crypt_stat->cipher[cipher_name_len] = '\0';
1032         crypt_stat->key_size =
1033                 mount_crypt_stat->global_default_cipher_key_size;
1034         ecryptfs_generate_new_key(crypt_stat);
1035         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1036         if (rc)
1037                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1038                                 "context for cipher [%s]: rc = [%d]\n",
1039                                 crypt_stat->cipher, rc);
1040 out:
1041         return rc;
1042 }
1043
1044 /**
1045  * ecryptfs_validate_marker - check for the ecryptfs marker
1046  * @data: The data block in which to check
1047  *
1048  * Returns zero if marker found; -EINVAL if not found
1049  */
1050 static int ecryptfs_validate_marker(char *data)
1051 {
1052         u32 m_1, m_2;
1053
1054         m_1 = get_unaligned_be32(data);
1055         m_2 = get_unaligned_be32(data + 4);
1056         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1057                 return 0;
1058         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1059                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1060                         MAGIC_ECRYPTFS_MARKER);
1061         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1062                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1063         return -EINVAL;
1064 }
1065
1066 struct ecryptfs_flag_map_elem {
1067         u32 file_flag;
1068         u32 local_flag;
1069 };
1070
1071 /* Add support for additional flags by adding elements here. */
1072 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1073         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1074         {0x00000002, ECRYPTFS_ENCRYPTED},
1075         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1076         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1077 };
1078
1079 /**
1080  * ecryptfs_process_flags
1081  * @crypt_stat: The cryptographic context
1082  * @page_virt: Source data to be parsed
1083  * @bytes_read: Updated with the number of bytes read
1084  *
1085  * Returns zero on success; non-zero if the flag set is invalid
1086  */
1087 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1088                                   char *page_virt, int *bytes_read)
1089 {
1090         int rc = 0;
1091         int i;
1092         u32 flags;
1093
1094         flags = get_unaligned_be32(page_virt);
1095         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1096                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1097                 if (flags & ecryptfs_flag_map[i].file_flag) {
1098                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1099                 } else
1100                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1101         /* Version is in top 8 bits of the 32-bit flag vector */
1102         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1103         (*bytes_read) = 4;
1104         return rc;
1105 }
1106
1107 /**
1108  * write_ecryptfs_marker
1109  * @page_virt: The pointer to in a page to begin writing the marker
1110  * @written: Number of bytes written
1111  *
1112  * Marker = 0x3c81b7f5
1113  */
1114 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1115 {
1116         u32 m_1, m_2;
1117
1118         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1119         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1120         put_unaligned_be32(m_1, page_virt);
1121         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1122         put_unaligned_be32(m_2, page_virt);
1123         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1124 }
1125
1126 void ecryptfs_write_crypt_stat_flags(char *page_virt,
1127                                      struct ecryptfs_crypt_stat *crypt_stat,
1128                                      size_t *written)
1129 {
1130         u32 flags = 0;
1131         int i;
1132
1133         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1134                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1135                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1136                         flags |= ecryptfs_flag_map[i].file_flag;
1137         /* Version is in top 8 bits of the 32-bit flag vector */
1138         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1139         put_unaligned_be32(flags, page_virt);
1140         (*written) = 4;
1141 }
1142
1143 struct ecryptfs_cipher_code_str_map_elem {
1144         char cipher_str[16];
1145         u8 cipher_code;
1146 };
1147
1148 /* Add support for additional ciphers by adding elements here. The
1149  * cipher_code is whatever OpenPGP applicatoins use to identify the
1150  * ciphers. List in order of probability. */
1151 static struct ecryptfs_cipher_code_str_map_elem
1152 ecryptfs_cipher_code_str_map[] = {
1153         {"aes",RFC2440_CIPHER_AES_128 },
1154         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1155         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1156         {"cast5", RFC2440_CIPHER_CAST_5},
1157         {"twofish", RFC2440_CIPHER_TWOFISH},
1158         {"cast6", RFC2440_CIPHER_CAST_6},
1159         {"aes", RFC2440_CIPHER_AES_192},
1160         {"aes", RFC2440_CIPHER_AES_256}
1161 };
1162
1163 /**
1164  * ecryptfs_code_for_cipher_string
1165  * @cipher_name: The string alias for the cipher
1166  * @key_bytes: Length of key in bytes; used for AES code selection
1167  *
1168  * Returns zero on no match, or the cipher code on match
1169  */
1170 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1171 {
1172         int i;
1173         u8 code = 0;
1174         struct ecryptfs_cipher_code_str_map_elem *map =
1175                 ecryptfs_cipher_code_str_map;
1176
1177         if (strcmp(cipher_name, "aes") == 0) {
1178                 switch (key_bytes) {
1179                 case 16:
1180                         code = RFC2440_CIPHER_AES_128;
1181                         break;
1182                 case 24:
1183                         code = RFC2440_CIPHER_AES_192;
1184                         break;
1185                 case 32:
1186                         code = RFC2440_CIPHER_AES_256;
1187                 }
1188         } else {
1189                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1190                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1191                                 code = map[i].cipher_code;
1192                                 break;
1193                         }
1194         }
1195         return code;
1196 }
1197
1198 /**
1199  * ecryptfs_cipher_code_to_string
1200  * @str: Destination to write out the cipher name
1201  * @cipher_code: The code to convert to cipher name string
1202  *
1203  * Returns zero on success
1204  */
1205 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1206 {
1207         int rc = 0;
1208         int i;
1209
1210         str[0] = '\0';
1211         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1212                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1213                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1214         if (str[0] == '\0') {
1215                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1216                                 "[%d]\n", cipher_code);
1217                 rc = -EINVAL;
1218         }
1219         return rc;
1220 }
1221
1222 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1223 {
1224         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1225         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1226         int rc;
1227
1228         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1229                                  inode);
1230         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1231                 return rc >= 0 ? -EINVAL : rc;
1232         rc = ecryptfs_validate_marker(marker);
1233         if (!rc)
1234                 ecryptfs_i_size_init(file_size, inode);
1235         return rc;
1236 }
1237
1238 void
1239 ecryptfs_write_header_metadata(char *virt,
1240                                struct ecryptfs_crypt_stat *crypt_stat,
1241                                size_t *written)
1242 {
1243         u32 header_extent_size;
1244         u16 num_header_extents_at_front;
1245
1246         header_extent_size = (u32)crypt_stat->extent_size;
1247         num_header_extents_at_front =
1248                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1249         put_unaligned_be32(header_extent_size, virt);
1250         virt += 4;
1251         put_unaligned_be16(num_header_extents_at_front, virt);
1252         (*written) = 6;
1253 }
1254
1255 struct kmem_cache *ecryptfs_header_cache;
1256
1257 /**
1258  * ecryptfs_write_headers_virt
1259  * @page_virt: The virtual address to write the headers to
1260  * @max: The size of memory allocated at page_virt
1261  * @size: Set to the number of bytes written by this function
1262  * @crypt_stat: The cryptographic context
1263  * @ecryptfs_dentry: The eCryptfs dentry
1264  *
1265  * Format version: 1
1266  *
1267  *   Header Extent:
1268  *     Octets 0-7:        Unencrypted file size (big-endian)
1269  *     Octets 8-15:       eCryptfs special marker
1270  *     Octets 16-19:      Flags
1271  *      Octet 16:         File format version number (between 0 and 255)
1272  *      Octets 17-18:     Reserved
1273  *      Octet 19:         Bit 1 (lsb): Reserved
1274  *                        Bit 2: Encrypted?
1275  *                        Bits 3-8: Reserved
1276  *     Octets 20-23:      Header extent size (big-endian)
1277  *     Octets 24-25:      Number of header extents at front of file
1278  *                        (big-endian)
1279  *     Octet  26:         Begin RFC 2440 authentication token packet set
1280  *   Data Extent 0:
1281  *     Lower data (CBC encrypted)
1282  *   Data Extent 1:
1283  *     Lower data (CBC encrypted)
1284  *   ...
1285  *
1286  * Returns zero on success
1287  */
1288 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1289                                        size_t *size,
1290                                        struct ecryptfs_crypt_stat *crypt_stat,
1291                                        struct dentry *ecryptfs_dentry)
1292 {
1293         int rc;
1294         size_t written;
1295         size_t offset;
1296
1297         offset = ECRYPTFS_FILE_SIZE_BYTES;
1298         write_ecryptfs_marker((page_virt + offset), &written);
1299         offset += written;
1300         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1301                                         &written);
1302         offset += written;
1303         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1304                                        &written);
1305         offset += written;
1306         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1307                                               ecryptfs_dentry, &written,
1308                                               max - offset);
1309         if (rc)
1310                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1311                                 "set; rc = [%d]\n", rc);
1312         if (size) {
1313                 offset += written;
1314                 *size = offset;
1315         }
1316         return rc;
1317 }
1318
1319 static int
1320 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1321                                     char *virt, size_t virt_len)
1322 {
1323         int rc;
1324
1325         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1326                                   0, virt_len);
1327         if (rc < 0)
1328                 printk(KERN_ERR "%s: Error attempting to write header "
1329                        "information to lower file; rc = [%d]\n", __func__, rc);
1330         else
1331                 rc = 0;
1332         return rc;
1333 }
1334
1335 static int
1336 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1337                                  char *page_virt, size_t size)
1338 {
1339         int rc;
1340
1341         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1342                                size, 0);
1343         return rc;
1344 }
1345
1346 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1347                                                unsigned int order)
1348 {
1349         struct page *page;
1350
1351         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1352         if (page)
1353                 return (unsigned long) page_address(page);
1354         return 0;
1355 }
1356
1357 /**
1358  * ecryptfs_write_metadata
1359  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1360  * @ecryptfs_inode: The newly created eCryptfs inode
1361  *
1362  * Write the file headers out.  This will likely involve a userspace
1363  * callout, in which the session key is encrypted with one or more
1364  * public keys and/or the passphrase necessary to do the encryption is
1365  * retrieved via a prompt.  Exactly what happens at this point should
1366  * be policy-dependent.
1367  *
1368  * Returns zero on success; non-zero on error
1369  */
1370 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1371                             struct inode *ecryptfs_inode)
1372 {
1373         struct ecryptfs_crypt_stat *crypt_stat =
1374                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1375         unsigned int order;
1376         char *virt;
1377         size_t virt_len;
1378         size_t size = 0;
1379         int rc = 0;
1380
1381         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1382                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1383                         printk(KERN_ERR "Key is invalid; bailing out\n");
1384                         rc = -EINVAL;
1385                         goto out;
1386                 }
1387         } else {
1388                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1389                        __func__);
1390                 rc = -EINVAL;
1391                 goto out;
1392         }
1393         virt_len = crypt_stat->metadata_size;
1394         order = get_order(virt_len);
1395         /* Released in this function */
1396         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1397         if (!virt) {
1398                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1399                 rc = -ENOMEM;
1400                 goto out;
1401         }
1402         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1403         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1404                                          ecryptfs_dentry);
1405         if (unlikely(rc)) {
1406                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1407                        __func__, rc);
1408                 goto out_free;
1409         }
1410         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1411                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1412                                                       size);
1413         else
1414                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1415                                                          virt_len);
1416         if (rc) {
1417                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1418                        "rc = [%d]\n", __func__, rc);
1419                 goto out_free;
1420         }
1421 out_free:
1422         free_pages((unsigned long)virt, order);
1423 out:
1424         return rc;
1425 }
1426
1427 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1428 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1429 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1430                                  char *virt, int *bytes_read,
1431                                  int validate_header_size)
1432 {
1433         int rc = 0;
1434         u32 header_extent_size;
1435         u16 num_header_extents_at_front;
1436
1437         header_extent_size = get_unaligned_be32(virt);
1438         virt += sizeof(__be32);
1439         num_header_extents_at_front = get_unaligned_be16(virt);
1440         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1441                                      * (size_t)header_extent_size));
1442         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1443         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1444             && (crypt_stat->metadata_size
1445                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1446                 rc = -EINVAL;
1447                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1448                        crypt_stat->metadata_size);
1449         }
1450         return rc;
1451 }
1452
1453 /**
1454  * set_default_header_data
1455  * @crypt_stat: The cryptographic context
1456  *
1457  * For version 0 file format; this function is only for backwards
1458  * compatibility for files created with the prior versions of
1459  * eCryptfs.
1460  */
1461 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1462 {
1463         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1464 }
1465
1466 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1467 {
1468         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1469         struct ecryptfs_crypt_stat *crypt_stat;
1470         u64 file_size;
1471
1472         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1473         mount_crypt_stat =
1474                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1475         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1476                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1477                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1478                         file_size += crypt_stat->metadata_size;
1479         } else
1480                 file_size = get_unaligned_be64(page_virt);
1481         i_size_write(inode, (loff_t)file_size);
1482         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1483 }
1484
1485 /**
1486  * ecryptfs_read_headers_virt
1487  * @page_virt: The virtual address into which to read the headers
1488  * @crypt_stat: The cryptographic context
1489  * @ecryptfs_dentry: The eCryptfs dentry
1490  * @validate_header_size: Whether to validate the header size while reading
1491  *
1492  * Read/parse the header data. The header format is detailed in the
1493  * comment block for the ecryptfs_write_headers_virt() function.
1494  *
1495  * Returns zero on success
1496  */
1497 static int ecryptfs_read_headers_virt(char *page_virt,
1498                                       struct ecryptfs_crypt_stat *crypt_stat,
1499                                       struct dentry *ecryptfs_dentry,
1500                                       int validate_header_size)
1501 {
1502         int rc = 0;
1503         int offset;
1504         int bytes_read;
1505
1506         ecryptfs_set_default_sizes(crypt_stat);
1507         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1508                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1509         offset = ECRYPTFS_FILE_SIZE_BYTES;
1510         rc = ecryptfs_validate_marker(page_virt + offset);
1511         if (rc)
1512                 goto out;
1513         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1514                 ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1515         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1516         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1517                                     &bytes_read);
1518         if (rc) {
1519                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1520                 goto out;
1521         }
1522         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1523                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1524                                 "file version [%d] is supported by this "
1525                                 "version of eCryptfs\n",
1526                                 crypt_stat->file_version,
1527                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1528                 rc = -EINVAL;
1529                 goto out;
1530         }
1531         offset += bytes_read;
1532         if (crypt_stat->file_version >= 1) {
1533                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1534                                            &bytes_read, validate_header_size);
1535                 if (rc) {
1536                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1537                                         "metadata; rc = [%d]\n", rc);
1538                 }
1539                 offset += bytes_read;
1540         } else
1541                 set_default_header_data(crypt_stat);
1542         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1543                                        ecryptfs_dentry);
1544 out:
1545         return rc;
1546 }
1547
1548 /**
1549  * ecryptfs_read_xattr_region
1550  * @page_virt: The vitual address into which to read the xattr data
1551  * @ecryptfs_inode: The eCryptfs inode
1552  *
1553  * Attempts to read the crypto metadata from the extended attribute
1554  * region of the lower file.
1555  *
1556  * Returns zero on success; non-zero on error
1557  */
1558 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1559 {
1560         struct dentry *lower_dentry =
1561                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1562         ssize_t size;
1563         int rc = 0;
1564
1565         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1566                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1567         if (size < 0) {
1568                 if (unlikely(ecryptfs_verbosity > 0))
1569                         printk(KERN_INFO "Error attempting to read the [%s] "
1570                                "xattr from the lower file; return value = "
1571                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1572                 rc = -EINVAL;
1573                 goto out;
1574         }
1575 out:
1576         return rc;
1577 }
1578
1579 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1580                                             struct inode *inode)
1581 {
1582         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1583         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1584         int rc;
1585
1586         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1587                                      ECRYPTFS_XATTR_NAME, file_size,
1588                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1589         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1590                 return rc >= 0 ? -EINVAL : rc;
1591         rc = ecryptfs_validate_marker(marker);
1592         if (!rc)
1593                 ecryptfs_i_size_init(file_size, inode);
1594         return rc;
1595 }
1596
1597 /**
1598  * ecryptfs_read_metadata
1599  *
1600  * Common entry point for reading file metadata. From here, we could
1601  * retrieve the header information from the header region of the file,
1602  * the xattr region of the file, or some other repostory that is
1603  * stored separately from the file itself. The current implementation
1604  * supports retrieving the metadata information from the file contents
1605  * and from the xattr region.
1606  *
1607  * Returns zero if valid headers found and parsed; non-zero otherwise
1608  */
1609 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1610 {
1611         int rc;
1612         char *page_virt;
1613         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1614         struct ecryptfs_crypt_stat *crypt_stat =
1615             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1616         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1617                 &ecryptfs_superblock_to_private(
1618                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1619
1620         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1621                                                       mount_crypt_stat);
1622         /* Read the first page from the underlying file */
1623         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1624         if (!page_virt) {
1625                 rc = -ENOMEM;
1626                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1627                        __func__);
1628                 goto out;
1629         }
1630         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1631                                  ecryptfs_inode);
1632         if (rc >= 0)
1633                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1634                                                 ecryptfs_dentry,
1635                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1636         if (rc) {
1637                 /* metadata is not in the file header, so try xattrs */
1638                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1639                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1640                 if (rc) {
1641                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1642                                "file header region or xattr region, inode %lu\n",
1643                                 ecryptfs_inode->i_ino);
1644                         rc = -EINVAL;
1645                         goto out;
1646                 }
1647                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1648                                                 ecryptfs_dentry,
1649                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1650                 if (rc) {
1651                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1652                                "file xattr region either, inode %lu\n",
1653                                 ecryptfs_inode->i_ino);
1654                         rc = -EINVAL;
1655                 }
1656                 if (crypt_stat->mount_crypt_stat->flags
1657                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1658                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1659                 } else {
1660                         printk(KERN_WARNING "Attempt to access file with "
1661                                "crypto metadata only in the extended attribute "
1662                                "region, but eCryptfs was mounted without "
1663                                "xattr support enabled. eCryptfs will not treat "
1664                                "this like an encrypted file, inode %lu\n",
1665                                 ecryptfs_inode->i_ino);
1666                         rc = -EINVAL;
1667                 }
1668         }
1669 out:
1670         if (page_virt) {
1671                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1672                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1673         }
1674         return rc;
1675 }
1676
1677 /**
1678  * ecryptfs_encrypt_filename - encrypt filename
1679  *
1680  * CBC-encrypts the filename. We do not want to encrypt the same
1681  * filename with the same key and IV, which may happen with hard
1682  * links, so we prepend random bits to each filename.
1683  *
1684  * Returns zero on success; non-zero otherwise
1685  */
1686 static int
1687 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1688                           struct ecryptfs_crypt_stat *crypt_stat,
1689                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1690 {
1691         int rc = 0;
1692
1693         filename->encrypted_filename = NULL;
1694         filename->encrypted_filename_size = 0;
1695         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1696             || (mount_crypt_stat && (mount_crypt_stat->flags
1697                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1698                 size_t packet_size;
1699                 size_t remaining_bytes;
1700
1701                 rc = ecryptfs_write_tag_70_packet(
1702                         NULL, NULL,
1703                         &filename->encrypted_filename_size,
1704                         mount_crypt_stat, NULL,
1705                         filename->filename_size);
1706                 if (rc) {
1707                         printk(KERN_ERR "%s: Error attempting to get packet "
1708                                "size for tag 72; rc = [%d]\n", __func__,
1709                                rc);
1710                         filename->encrypted_filename_size = 0;
1711                         goto out;
1712                 }
1713                 filename->encrypted_filename =
1714                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1715                 if (!filename->encrypted_filename) {
1716                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1717                                "to kmalloc [%zd] bytes\n", __func__,
1718                                filename->encrypted_filename_size);
1719                         rc = -ENOMEM;
1720                         goto out;
1721                 }
1722                 remaining_bytes = filename->encrypted_filename_size;
1723                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1724                                                   &remaining_bytes,
1725                                                   &packet_size,
1726                                                   mount_crypt_stat,
1727                                                   filename->filename,
1728                                                   filename->filename_size);
1729                 if (rc) {
1730                         printk(KERN_ERR "%s: Error attempting to generate "
1731                                "tag 70 packet; rc = [%d]\n", __func__,
1732                                rc);
1733                         kfree(filename->encrypted_filename);
1734                         filename->encrypted_filename = NULL;
1735                         filename->encrypted_filename_size = 0;
1736                         goto out;
1737                 }
1738                 filename->encrypted_filename_size = packet_size;
1739         } else {
1740                 printk(KERN_ERR "%s: No support for requested filename "
1741                        "encryption method in this release\n", __func__);
1742                 rc = -EOPNOTSUPP;
1743                 goto out;
1744         }
1745 out:
1746         return rc;
1747 }
1748
1749 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1750                                   const char *name, size_t name_size)
1751 {
1752         int rc = 0;
1753
1754         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1755         if (!(*copied_name)) {
1756                 rc = -ENOMEM;
1757                 goto out;
1758         }
1759         memcpy((void *)(*copied_name), (void *)name, name_size);
1760         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1761                                                  * in printing out the
1762                                                  * string in debug
1763                                                  * messages */
1764         (*copied_name_size) = name_size;
1765 out:
1766         return rc;
1767 }
1768
1769 /**
1770  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1771  * @key_tfm: Crypto context for key material, set by this function
1772  * @cipher_name: Name of the cipher
1773  * @key_size: Size of the key in bytes
1774  *
1775  * Returns zero on success. Any crypto_tfm structs allocated here
1776  * should be released by other functions, such as on a superblock put
1777  * event, regardless of whether this function succeeds for fails.
1778  */
1779 static int
1780 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1781                             char *cipher_name, size_t *key_size)
1782 {
1783         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1784         char *full_alg_name = NULL;
1785         int rc;
1786
1787         *key_tfm = NULL;
1788         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1789                 rc = -EINVAL;
1790                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1791                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1792                 goto out;
1793         }
1794         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1795                                                     "ecb");
1796         if (rc)
1797                 goto out;
1798         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1799         if (IS_ERR(*key_tfm)) {
1800                 rc = PTR_ERR(*key_tfm);
1801                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1802                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1803                 goto out;
1804         }
1805         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1806         if (*key_size == 0) {
1807                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1808
1809                 *key_size = alg->max_keysize;
1810         }
1811         get_random_bytes(dummy_key, *key_size);
1812         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1813         if (rc) {
1814                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1815                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1816                        rc);
1817                 rc = -EINVAL;
1818                 goto out;
1819         }
1820 out:
1821         kfree(full_alg_name);
1822         return rc;
1823 }
1824
1825 struct kmem_cache *ecryptfs_key_tfm_cache;
1826 static struct list_head key_tfm_list;
1827 struct mutex key_tfm_list_mutex;
1828
1829 int __init ecryptfs_init_crypto(void)
1830 {
1831         mutex_init(&key_tfm_list_mutex);
1832         INIT_LIST_HEAD(&key_tfm_list);
1833         return 0;
1834 }
1835
1836 /**
1837  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1838  *
1839  * Called only at module unload time
1840  */
1841 int ecryptfs_destroy_crypto(void)
1842 {
1843         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1844
1845         mutex_lock(&key_tfm_list_mutex);
1846         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1847                                  key_tfm_list) {
1848                 list_del(&key_tfm->key_tfm_list);
1849                 if (key_tfm->key_tfm)
1850                         crypto_free_blkcipher(key_tfm->key_tfm);
1851                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1852         }
1853         mutex_unlock(&key_tfm_list_mutex);
1854         return 0;
1855 }
1856
1857 int
1858 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1859                          size_t key_size)
1860 {
1861         struct ecryptfs_key_tfm *tmp_tfm;
1862         int rc = 0;
1863
1864         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1865
1866         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1867         if (key_tfm != NULL)
1868                 (*key_tfm) = tmp_tfm;
1869         if (!tmp_tfm) {
1870                 rc = -ENOMEM;
1871                 printk(KERN_ERR "Error attempting to allocate from "
1872                        "ecryptfs_key_tfm_cache\n");
1873                 goto out;
1874         }
1875         mutex_init(&tmp_tfm->key_tfm_mutex);
1876         strncpy(tmp_tfm->cipher_name, cipher_name,
1877                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1878         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1879         tmp_tfm->key_size = key_size;
1880         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1881                                          tmp_tfm->cipher_name,
1882                                          &tmp_tfm->key_size);
1883         if (rc) {
1884                 printk(KERN_ERR "Error attempting to initialize key TFM "
1885                        "cipher with name = [%s]; rc = [%d]\n",
1886                        tmp_tfm->cipher_name, rc);
1887                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1888                 if (key_tfm != NULL)
1889                         (*key_tfm) = NULL;
1890                 goto out;
1891         }
1892         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1893 out:
1894         return rc;
1895 }
1896
1897 /**
1898  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1899  * @cipher_name: the name of the cipher to search for
1900  * @key_tfm: set to corresponding tfm if found
1901  *
1902  * Searches for cached key_tfm matching @cipher_name
1903  * Must be called with &key_tfm_list_mutex held
1904  * Returns 1 if found, with @key_tfm set
1905  * Returns 0 if not found, with @key_tfm set to NULL
1906  */
1907 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1908 {
1909         struct ecryptfs_key_tfm *tmp_key_tfm;
1910
1911         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1912
1913         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1914                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1915                         if (key_tfm)
1916                                 (*key_tfm) = tmp_key_tfm;
1917                         return 1;
1918                 }
1919         }
1920         if (key_tfm)
1921                 (*key_tfm) = NULL;
1922         return 0;
1923 }
1924
1925 /**
1926  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1927  *
1928  * @tfm: set to cached tfm found, or new tfm created
1929  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1930  * @cipher_name: the name of the cipher to search for and/or add
1931  *
1932  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1933  * Searches for cached item first, and creates new if not found.
1934  * Returns 0 on success, non-zero if adding new cipher failed
1935  */
1936 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1937                                                struct mutex **tfm_mutex,
1938                                                char *cipher_name)
1939 {
1940         struct ecryptfs_key_tfm *key_tfm;
1941         int rc = 0;
1942
1943         (*tfm) = NULL;
1944         (*tfm_mutex) = NULL;
1945
1946         mutex_lock(&key_tfm_list_mutex);
1947         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1948                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1949                 if (rc) {
1950                         printk(KERN_ERR "Error adding new key_tfm to list; "
1951                                         "rc = [%d]\n", rc);
1952                         goto out;
1953                 }
1954         }
1955         (*tfm) = key_tfm->key_tfm;
1956         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1957 out:
1958         mutex_unlock(&key_tfm_list_mutex);
1959         return rc;
1960 }
1961
1962 /* 64 characters forming a 6-bit target field */
1963 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1964                                                  "EFGHIJKLMNOPQRST"
1965                                                  "UVWXYZabcdefghij"
1966                                                  "klmnopqrstuvwxyz");
1967
1968 /* We could either offset on every reverse map or just pad some 0x00's
1969  * at the front here */
1970 static const unsigned char filename_rev_map[256] = {
1971         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1972         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1973         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1974         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1975         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1976         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1977         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1978         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1979         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1980         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1981         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1982         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1983         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1984         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1985         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1986         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1987 };
1988
1989 /**
1990  * ecryptfs_encode_for_filename
1991  * @dst: Destination location for encoded filename
1992  * @dst_size: Size of the encoded filename in bytes
1993  * @src: Source location for the filename to encode
1994  * @src_size: Size of the source in bytes
1995  */
1996 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1997                                   unsigned char *src, size_t src_size)
1998 {
1999         size_t num_blocks;
2000         size_t block_num = 0;
2001         size_t dst_offset = 0;
2002         unsigned char last_block[3];
2003
2004         if (src_size == 0) {
2005                 (*dst_size) = 0;
2006                 goto out;
2007         }
2008         num_blocks = (src_size / 3);
2009         if ((src_size % 3) == 0) {
2010                 memcpy(last_block, (&src[src_size - 3]), 3);
2011         } else {
2012                 num_blocks++;
2013                 last_block[2] = 0x00;
2014                 switch (src_size % 3) {
2015                 case 1:
2016                         last_block[0] = src[src_size - 1];
2017                         last_block[1] = 0x00;
2018                         break;
2019                 case 2:
2020                         last_block[0] = src[src_size - 2];
2021                         last_block[1] = src[src_size - 1];
2022                 }
2023         }
2024         (*dst_size) = (num_blocks * 4);
2025         if (!dst)
2026                 goto out;
2027         while (block_num < num_blocks) {
2028                 unsigned char *src_block;
2029                 unsigned char dst_block[4];
2030
2031                 if (block_num == (num_blocks - 1))
2032                         src_block = last_block;
2033                 else
2034                         src_block = &src[block_num * 3];
2035                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
2036                 dst_block[1] = (((src_block[0] << 4) & 0x30)
2037                                 | ((src_block[1] >> 4) & 0x0F));
2038                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
2039                                 | ((src_block[2] >> 6) & 0x03));
2040                 dst_block[3] = (src_block[2] & 0x3F);
2041                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
2042                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
2043                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
2044                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
2045                 block_num++;
2046         }
2047 out:
2048         return;
2049 }
2050
2051 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
2052 {
2053         /* Not exact; conservatively long. Every block of 4
2054          * encoded characters decodes into a block of 3
2055          * decoded characters. This segment of code provides
2056          * the caller with the maximum amount of allocated
2057          * space that @dst will need to point to in a
2058          * subsequent call. */
2059         return ((encoded_size + 1) * 3) / 4;
2060 }
2061
2062 /**
2063  * ecryptfs_decode_from_filename
2064  * @dst: If NULL, this function only sets @dst_size and returns. If
2065  *       non-NULL, this function decodes the encoded octets in @src
2066  *       into the memory that @dst points to.
2067  * @dst_size: Set to the size of the decoded string.
2068  * @src: The encoded set of octets to decode.
2069  * @src_size: The size of the encoded set of octets to decode.
2070  */
2071 static void
2072 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2073                               const unsigned char *src, size_t src_size)
2074 {
2075         u8 current_bit_offset = 0;
2076         size_t src_byte_offset = 0;
2077         size_t dst_byte_offset = 0;
2078
2079         if (dst == NULL) {
2080                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
2081                 goto out;
2082         }
2083         while (src_byte_offset < src_size) {
2084                 unsigned char src_byte =
2085                                 filename_rev_map[(int)src[src_byte_offset]];
2086
2087                 switch (current_bit_offset) {
2088                 case 0:
2089                         dst[dst_byte_offset] = (src_byte << 2);
2090                         current_bit_offset = 6;
2091                         break;
2092                 case 6:
2093                         dst[dst_byte_offset++] |= (src_byte >> 4);
2094                         dst[dst_byte_offset] = ((src_byte & 0xF)
2095                                                  << 4);
2096                         current_bit_offset = 4;
2097                         break;
2098                 case 4:
2099                         dst[dst_byte_offset++] |= (src_byte >> 2);
2100                         dst[dst_byte_offset] = (src_byte << 6);
2101                         current_bit_offset = 2;
2102                         break;
2103                 case 2:
2104                         dst[dst_byte_offset++] |= (src_byte);
2105                         dst[dst_byte_offset] = 0;
2106                         current_bit_offset = 0;
2107                         break;
2108                 }
2109                 src_byte_offset++;
2110         }
2111         (*dst_size) = dst_byte_offset;
2112 out:
2113         return;
2114 }
2115
2116 /**
2117  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2118  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2119  * @name: The plaintext name
2120  * @length: The length of the plaintext
2121  * @encoded_name: The encypted name
2122  *
2123  * Encrypts and encodes a filename into something that constitutes a
2124  * valid filename for a filesystem, with printable characters.
2125  *
2126  * We assume that we have a properly initialized crypto context,
2127  * pointed to by crypt_stat->tfm.
2128  *
2129  * Returns zero on success; non-zero on otherwise
2130  */
2131 int ecryptfs_encrypt_and_encode_filename(
2132         char **encoded_name,
2133         size_t *encoded_name_size,
2134         struct ecryptfs_crypt_stat *crypt_stat,
2135         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2136         const char *name, size_t name_size)
2137 {
2138         size_t encoded_name_no_prefix_size;
2139         int rc = 0;
2140
2141         (*encoded_name) = NULL;
2142         (*encoded_name_size) = 0;
2143         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2144             || (mount_crypt_stat && (mount_crypt_stat->flags
2145                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2146                 struct ecryptfs_filename *filename;
2147
2148                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2149                 if (!filename) {
2150                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2151                                "to kzalloc [%zd] bytes\n", __func__,
2152                                sizeof(*filename));
2153                         rc = -ENOMEM;
2154                         goto out;
2155                 }
2156                 filename->filename = (char *)name;
2157                 filename->filename_size = name_size;
2158                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2159                                                mount_crypt_stat);
2160                 if (rc) {
2161                         printk(KERN_ERR "%s: Error attempting to encrypt "
2162                                "filename; rc = [%d]\n", __func__, rc);
2163                         kfree(filename);
2164                         goto out;
2165                 }
2166                 ecryptfs_encode_for_filename(
2167                         NULL, &encoded_name_no_prefix_size,
2168                         filename->encrypted_filename,
2169                         filename->encrypted_filename_size);
2170                 if ((crypt_stat && (crypt_stat->flags
2171                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2172                     || (mount_crypt_stat
2173                         && (mount_crypt_stat->flags
2174                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2175                         (*encoded_name_size) =
2176                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2177                                  + encoded_name_no_prefix_size);
2178                 else
2179                         (*encoded_name_size) =
2180                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2181                                  + encoded_name_no_prefix_size);
2182                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2183                 if (!(*encoded_name)) {
2184                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2185                                "to kzalloc [%zd] bytes\n", __func__,
2186                                (*encoded_name_size));
2187                         rc = -ENOMEM;
2188                         kfree(filename->encrypted_filename);
2189                         kfree(filename);
2190                         goto out;
2191                 }
2192                 if ((crypt_stat && (crypt_stat->flags
2193                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2194                     || (mount_crypt_stat
2195                         && (mount_crypt_stat->flags
2196                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2197                         memcpy((*encoded_name),
2198                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2199                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2200                         ecryptfs_encode_for_filename(
2201                             ((*encoded_name)
2202                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2203                             &encoded_name_no_prefix_size,
2204                             filename->encrypted_filename,
2205                             filename->encrypted_filename_size);
2206                         (*encoded_name_size) =
2207                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2208                                  + encoded_name_no_prefix_size);
2209                         (*encoded_name)[(*encoded_name_size)] = '\0';
2210                 } else {
2211                         rc = -EOPNOTSUPP;
2212                 }
2213                 if (rc) {
2214                         printk(KERN_ERR "%s: Error attempting to encode "
2215                                "encrypted filename; rc = [%d]\n", __func__,
2216                                rc);
2217                         kfree((*encoded_name));
2218                         (*encoded_name) = NULL;
2219                         (*encoded_name_size) = 0;
2220                 }
2221                 kfree(filename->encrypted_filename);
2222                 kfree(filename);
2223         } else {
2224                 rc = ecryptfs_copy_filename(encoded_name,
2225                                             encoded_name_size,
2226                                             name, name_size);
2227         }
2228 out:
2229         return rc;
2230 }
2231
2232 /**
2233  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2234  * @plaintext_name: The plaintext name
2235  * @plaintext_name_size: The plaintext name size
2236  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2237  * @name: The filename in cipher text
2238  * @name_size: The cipher text name size
2239  *
2240  * Decrypts and decodes the filename.
2241  *
2242  * Returns zero on error; non-zero otherwise
2243  */
2244 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2245                                          size_t *plaintext_name_size,
2246                                          struct dentry *ecryptfs_dir_dentry,
2247                                          const char *name, size_t name_size)
2248 {
2249         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2250                 &ecryptfs_superblock_to_private(
2251                         ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2252         char *decoded_name;
2253         size_t decoded_name_size;
2254         size_t packet_size;
2255         int rc = 0;
2256
2257         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2258             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2259             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2260             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2261                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2262                 const char *orig_name = name;
2263                 size_t orig_name_size = name_size;
2264
2265                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2266                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2267                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2268                                               name, name_size);
2269                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2270                 if (!decoded_name) {
2271                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2272                                "to kmalloc [%zd] bytes\n", __func__,
2273                                decoded_name_size);
2274                         rc = -ENOMEM;
2275                         goto out;
2276                 }
2277                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2278                                               name, name_size);
2279                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2280                                                   plaintext_name_size,
2281                                                   &packet_size,
2282                                                   mount_crypt_stat,
2283                                                   decoded_name,
2284                                                   decoded_name_size);
2285                 if (rc) {
2286                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2287                                "from filename; copying through filename "
2288                                "as-is\n", __func__);
2289                         rc = ecryptfs_copy_filename(plaintext_name,
2290                                                     plaintext_name_size,
2291                                                     orig_name, orig_name_size);
2292                         goto out_free;
2293                 }
2294         } else {
2295                 rc = ecryptfs_copy_filename(plaintext_name,
2296                                             plaintext_name_size,
2297                                             name, name_size);
2298                 goto out;
2299         }
2300 out_free:
2301         kfree(decoded_name);
2302 out:
2303         return rc;
2304 }
2305
2306 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2307
2308 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2309                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2310 {
2311         struct blkcipher_desc desc;
2312         struct mutex *tfm_mutex;
2313         size_t cipher_blocksize;
2314         int rc;
2315
2316         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2317                 (*namelen) = lower_namelen;
2318                 return 0;
2319         }
2320
2321         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2322                         mount_crypt_stat->global_default_fn_cipher_name);
2323         if (unlikely(rc)) {
2324                 (*namelen) = 0;
2325                 return rc;
2326         }
2327
2328         mutex_lock(tfm_mutex);
2329         cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2330         mutex_unlock(tfm_mutex);
2331
2332         /* Return an exact amount for the common cases */
2333         if (lower_namelen == NAME_MAX
2334             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2335                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2336                 return 0;
2337         }
2338
2339         /* Return a safe estimate for the uncommon cases */
2340         (*namelen) = lower_namelen;
2341         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2342         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2343         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2344         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2345         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2346         /* Worst case is that the filename is padded nearly a full block size */
2347         (*namelen) -= cipher_blocksize - 1;
2348
2349         if ((*namelen) < 0)
2350                 (*namelen) = 0;
2351
2352         return 0;
2353 }