eCryptfs: Handle unrecognized tag 3 cipher codes
[linux-2.6.git] / fs / ecryptfs / crypto.c
1 /**
2  * eCryptfs: Linux filesystem encryption layer
3  *
4  * Copyright (C) 1997-2004 Erez Zadok
5  * Copyright (C) 2001-2004 Stony Brook University
6  * Copyright (C) 2004-2007 International Business Machines Corp.
7  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
8  *              Michael C. Thompson <mcthomps@us.ibm.com>
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License as
12  * published by the Free Software Foundation; either version 2 of the
13  * License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23  * 02111-1307, USA.
24  */
25
26 #include <linux/fs.h>
27 #include <linux/mount.h>
28 #include <linux/pagemap.h>
29 #include <linux/random.h>
30 #include <linux/compiler.h>
31 #include <linux/key.h>
32 #include <linux/namei.h>
33 #include <linux/crypto.h>
34 #include <linux/file.h>
35 #include <linux/scatterlist.h>
36 #include <asm/unaligned.h>
37 #include "ecryptfs_kernel.h"
38
39 static int
40 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
41                              struct page *dst_page, int dst_offset,
42                              struct page *src_page, int src_offset, int size,
43                              unsigned char *iv);
44 static int
45 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
46                              struct page *dst_page, int dst_offset,
47                              struct page *src_page, int src_offset, int size,
48                              unsigned char *iv);
49
50 /**
51  * ecryptfs_to_hex
52  * @dst: Buffer to take hex character representation of contents of
53  *       src; must be at least of size (src_size * 2)
54  * @src: Buffer to be converted to a hex string respresentation
55  * @src_size: number of bytes to convert
56  */
57 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
58 {
59         int x;
60
61         for (x = 0; x < src_size; x++)
62                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
63 }
64
65 /**
66  * ecryptfs_from_hex
67  * @dst: Buffer to take the bytes from src hex; must be at least of
68  *       size (src_size / 2)
69  * @src: Buffer to be converted from a hex string respresentation to raw value
70  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
71  */
72 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
73 {
74         int x;
75         char tmp[3] = { 0, };
76
77         for (x = 0; x < dst_size; x++) {
78                 tmp[0] = src[x * 2];
79                 tmp[1] = src[x * 2 + 1];
80                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
81         }
82 }
83
84 /**
85  * ecryptfs_calculate_md5 - calculates the md5 of @src
86  * @dst: Pointer to 16 bytes of allocated memory
87  * @crypt_stat: Pointer to crypt_stat struct for the current inode
88  * @src: Data to be md5'd
89  * @len: Length of @src
90  *
91  * Uses the allocated crypto context that crypt_stat references to
92  * generate the MD5 sum of the contents of src.
93  */
94 static int ecryptfs_calculate_md5(char *dst,
95                                   struct ecryptfs_crypt_stat *crypt_stat,
96                                   char *src, int len)
97 {
98         struct scatterlist sg;
99         struct hash_desc desc = {
100                 .tfm = crypt_stat->hash_tfm,
101                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
102         };
103         int rc = 0;
104
105         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
106         sg_init_one(&sg, (u8 *)src, len);
107         if (!desc.tfm) {
108                 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
109                                              CRYPTO_ALG_ASYNC);
110                 if (IS_ERR(desc.tfm)) {
111                         rc = PTR_ERR(desc.tfm);
112                         ecryptfs_printk(KERN_ERR, "Error attempting to "
113                                         "allocate crypto context; rc = [%d]\n",
114                                         rc);
115                         goto out;
116                 }
117                 crypt_stat->hash_tfm = desc.tfm;
118         }
119         rc = crypto_hash_init(&desc);
120         if (rc) {
121                 printk(KERN_ERR
122                        "%s: Error initializing crypto hash; rc = [%d]\n",
123                        __func__, rc);
124                 goto out;
125         }
126         rc = crypto_hash_update(&desc, &sg, len);
127         if (rc) {
128                 printk(KERN_ERR
129                        "%s: Error updating crypto hash; rc = [%d]\n",
130                        __func__, rc);
131                 goto out;
132         }
133         rc = crypto_hash_final(&desc, dst);
134         if (rc) {
135                 printk(KERN_ERR
136                        "%s: Error finalizing crypto hash; rc = [%d]\n",
137                        __func__, rc);
138                 goto out;
139         }
140 out:
141         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
142         return rc;
143 }
144
145 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
146                                                   char *cipher_name,
147                                                   char *chaining_modifier)
148 {
149         int cipher_name_len = strlen(cipher_name);
150         int chaining_modifier_len = strlen(chaining_modifier);
151         int algified_name_len;
152         int rc;
153
154         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
155         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
156         if (!(*algified_name)) {
157                 rc = -ENOMEM;
158                 goto out;
159         }
160         snprintf((*algified_name), algified_name_len, "%s(%s)",
161                  chaining_modifier, cipher_name);
162         rc = 0;
163 out:
164         return rc;
165 }
166
167 /**
168  * ecryptfs_derive_iv
169  * @iv: destination for the derived iv vale
170  * @crypt_stat: Pointer to crypt_stat struct for the current inode
171  * @offset: Offset of the extent whose IV we are to derive
172  *
173  * Generate the initialization vector from the given root IV and page
174  * offset.
175  *
176  * Returns zero on success; non-zero on error.
177  */
178 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
179                        loff_t offset)
180 {
181         int rc = 0;
182         char dst[MD5_DIGEST_SIZE];
183         char src[ECRYPTFS_MAX_IV_BYTES + 16];
184
185         if (unlikely(ecryptfs_verbosity > 0)) {
186                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
187                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
188         }
189         /* TODO: It is probably secure to just cast the least
190          * significant bits of the root IV into an unsigned long and
191          * add the offset to that rather than go through all this
192          * hashing business. -Halcrow */
193         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
194         memset((src + crypt_stat->iv_bytes), 0, 16);
195         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
196         if (unlikely(ecryptfs_verbosity > 0)) {
197                 ecryptfs_printk(KERN_DEBUG, "source:\n");
198                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
199         }
200         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
201                                     (crypt_stat->iv_bytes + 16));
202         if (rc) {
203                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
204                                 "MD5 while generating IV for a page\n");
205                 goto out;
206         }
207         memcpy(iv, dst, crypt_stat->iv_bytes);
208         if (unlikely(ecryptfs_verbosity > 0)) {
209                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
210                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
211         }
212 out:
213         return rc;
214 }
215
216 /**
217  * ecryptfs_init_crypt_stat
218  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
219  *
220  * Initialize the crypt_stat structure.
221  */
222 void
223 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
224 {
225         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
226         INIT_LIST_HEAD(&crypt_stat->keysig_list);
227         mutex_init(&crypt_stat->keysig_list_mutex);
228         mutex_init(&crypt_stat->cs_mutex);
229         mutex_init(&crypt_stat->cs_tfm_mutex);
230         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
231         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
232 }
233
234 /**
235  * ecryptfs_destroy_crypt_stat
236  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
237  *
238  * Releases all memory associated with a crypt_stat struct.
239  */
240 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
241 {
242         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
243
244         if (crypt_stat->tfm)
245                 crypto_free_blkcipher(crypt_stat->tfm);
246         if (crypt_stat->hash_tfm)
247                 crypto_free_hash(crypt_stat->hash_tfm);
248         list_for_each_entry_safe(key_sig, key_sig_tmp,
249                                  &crypt_stat->keysig_list, crypt_stat_list) {
250                 list_del(&key_sig->crypt_stat_list);
251                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
252         }
253         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
254 }
255
256 void ecryptfs_destroy_mount_crypt_stat(
257         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
258 {
259         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
260
261         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
262                 return;
263         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
264         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
265                                  &mount_crypt_stat->global_auth_tok_list,
266                                  mount_crypt_stat_list) {
267                 list_del(&auth_tok->mount_crypt_stat_list);
268                 mount_crypt_stat->num_global_auth_toks--;
269                 if (auth_tok->global_auth_tok_key
270                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
271                         key_put(auth_tok->global_auth_tok_key);
272                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
273         }
274         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
275         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
276 }
277
278 /**
279  * virt_to_scatterlist
280  * @addr: Virtual address
281  * @size: Size of data; should be an even multiple of the block size
282  * @sg: Pointer to scatterlist array; set to NULL to obtain only
283  *      the number of scatterlist structs required in array
284  * @sg_size: Max array size
285  *
286  * Fills in a scatterlist array with page references for a passed
287  * virtual address.
288  *
289  * Returns the number of scatterlist structs in array used
290  */
291 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
292                         int sg_size)
293 {
294         int i = 0;
295         struct page *pg;
296         int offset;
297         int remainder_of_page;
298
299         sg_init_table(sg, sg_size);
300
301         while (size > 0 && i < sg_size) {
302                 pg = virt_to_page(addr);
303                 offset = offset_in_page(addr);
304                 if (sg)
305                         sg_set_page(&sg[i], pg, 0, offset);
306                 remainder_of_page = PAGE_CACHE_SIZE - offset;
307                 if (size >= remainder_of_page) {
308                         if (sg)
309                                 sg[i].length = remainder_of_page;
310                         addr += remainder_of_page;
311                         size -= remainder_of_page;
312                 } else {
313                         if (sg)
314                                 sg[i].length = size;
315                         addr += size;
316                         size = 0;
317                 }
318                 i++;
319         }
320         if (size > 0)
321                 return -ENOMEM;
322         return i;
323 }
324
325 /**
326  * encrypt_scatterlist
327  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
328  * @dest_sg: Destination of encrypted data
329  * @src_sg: Data to be encrypted
330  * @size: Length of data to be encrypted
331  * @iv: iv to use during encryption
332  *
333  * Returns the number of bytes encrypted; negative value on error
334  */
335 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
336                                struct scatterlist *dest_sg,
337                                struct scatterlist *src_sg, int size,
338                                unsigned char *iv)
339 {
340         struct blkcipher_desc desc = {
341                 .tfm = crypt_stat->tfm,
342                 .info = iv,
343                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
344         };
345         int rc = 0;
346
347         BUG_ON(!crypt_stat || !crypt_stat->tfm
348                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
349         if (unlikely(ecryptfs_verbosity > 0)) {
350                 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
351                                 crypt_stat->key_size);
352                 ecryptfs_dump_hex(crypt_stat->key,
353                                   crypt_stat->key_size);
354         }
355         /* Consider doing this once, when the file is opened */
356         mutex_lock(&crypt_stat->cs_tfm_mutex);
357         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
358                 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
359                                              crypt_stat->key_size);
360                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
361         }
362         if (rc) {
363                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
364                                 rc);
365                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
366                 rc = -EINVAL;
367                 goto out;
368         }
369         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
370         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
371         mutex_unlock(&crypt_stat->cs_tfm_mutex);
372 out:
373         return rc;
374 }
375
376 /**
377  * ecryptfs_lower_offset_for_extent
378  *
379  * Convert an eCryptfs page index into a lower byte offset
380  */
381 static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
382                                              struct ecryptfs_crypt_stat *crypt_stat)
383 {
384         (*offset) = (crypt_stat->num_header_bytes_at_front
385                      + (crypt_stat->extent_size * extent_num));
386 }
387
388 /**
389  * ecryptfs_encrypt_extent
390  * @enc_extent_page: Allocated page into which to encrypt the data in
391  *                   @page
392  * @crypt_stat: crypt_stat containing cryptographic context for the
393  *              encryption operation
394  * @page: Page containing plaintext data extent to encrypt
395  * @extent_offset: Page extent offset for use in generating IV
396  *
397  * Encrypts one extent of data.
398  *
399  * Return zero on success; non-zero otherwise
400  */
401 static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
402                                    struct ecryptfs_crypt_stat *crypt_stat,
403                                    struct page *page,
404                                    unsigned long extent_offset)
405 {
406         loff_t extent_base;
407         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
408         int rc;
409
410         extent_base = (((loff_t)page->index)
411                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
412         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
413                                 (extent_base + extent_offset));
414         if (rc) {
415                 ecryptfs_printk(KERN_ERR, "Error attempting to "
416                                 "derive IV for extent [0x%.16x]; "
417                                 "rc = [%d]\n", (extent_base + extent_offset),
418                                 rc);
419                 goto out;
420         }
421         if (unlikely(ecryptfs_verbosity > 0)) {
422                 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
423                                 "with iv:\n");
424                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
425                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
426                                 "encryption:\n");
427                 ecryptfs_dump_hex((char *)
428                                   (page_address(page)
429                                    + (extent_offset * crypt_stat->extent_size)),
430                                   8);
431         }
432         rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
433                                           page, (extent_offset
434                                                  * crypt_stat->extent_size),
435                                           crypt_stat->extent_size, extent_iv);
436         if (rc < 0) {
437                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
438                        "page->index = [%ld], extent_offset = [%ld]; "
439                        "rc = [%d]\n", __func__, page->index, extent_offset,
440                        rc);
441                 goto out;
442         }
443         rc = 0;
444         if (unlikely(ecryptfs_verbosity > 0)) {
445                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
446                                 "rc = [%d]\n", (extent_base + extent_offset),
447                                 rc);
448                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
449                                 "encryption:\n");
450                 ecryptfs_dump_hex((char *)(page_address(enc_extent_page)), 8);
451         }
452 out:
453         return rc;
454 }
455
456 /**
457  * ecryptfs_encrypt_page
458  * @page: Page mapped from the eCryptfs inode for the file; contains
459  *        decrypted content that needs to be encrypted (to a temporary
460  *        page; not in place) and written out to the lower file
461  *
462  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
463  * that eCryptfs pages may straddle the lower pages -- for instance,
464  * if the file was created on a machine with an 8K page size
465  * (resulting in an 8K header), and then the file is copied onto a
466  * host with a 32K page size, then when reading page 0 of the eCryptfs
467  * file, 24K of page 0 of the lower file will be read and decrypted,
468  * and then 8K of page 1 of the lower file will be read and decrypted.
469  *
470  * Returns zero on success; negative on error
471  */
472 int ecryptfs_encrypt_page(struct page *page)
473 {
474         struct inode *ecryptfs_inode;
475         struct ecryptfs_crypt_stat *crypt_stat;
476         char *enc_extent_virt;
477         struct page *enc_extent_page = NULL;
478         loff_t extent_offset;
479         int rc = 0;
480
481         ecryptfs_inode = page->mapping->host;
482         crypt_stat =
483                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
484         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
485         enc_extent_page = alloc_page(GFP_USER);
486         if (!enc_extent_page) {
487                 rc = -ENOMEM;
488                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
489                                 "encrypted extent\n");
490                 goto out;
491         }
492         enc_extent_virt = kmap(enc_extent_page);
493         for (extent_offset = 0;
494              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
495              extent_offset++) {
496                 loff_t offset;
497
498                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
499                                              extent_offset);
500                 if (rc) {
501                         printk(KERN_ERR "%s: Error encrypting extent; "
502                                "rc = [%d]\n", __func__, rc);
503                         goto out;
504                 }
505                 ecryptfs_lower_offset_for_extent(
506                         &offset, ((((loff_t)page->index)
507                                    * (PAGE_CACHE_SIZE
508                                       / crypt_stat->extent_size))
509                                   + extent_offset), crypt_stat);
510                 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
511                                           offset, crypt_stat->extent_size);
512                 if (rc) {
513                         ecryptfs_printk(KERN_ERR, "Error attempting "
514                                         "to write lower page; rc = [%d]"
515                                         "\n", rc);
516                         goto out;
517                 }
518         }
519 out:
520         if (enc_extent_page) {
521                 kunmap(enc_extent_page);
522                 __free_page(enc_extent_page);
523         }
524         return rc;
525 }
526
527 static int ecryptfs_decrypt_extent(struct page *page,
528                                    struct ecryptfs_crypt_stat *crypt_stat,
529                                    struct page *enc_extent_page,
530                                    unsigned long extent_offset)
531 {
532         loff_t extent_base;
533         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
534         int rc;
535
536         extent_base = (((loff_t)page->index)
537                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
538         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
539                                 (extent_base + extent_offset));
540         if (rc) {
541                 ecryptfs_printk(KERN_ERR, "Error attempting to "
542                                 "derive IV for extent [0x%.16x]; "
543                                 "rc = [%d]\n", (extent_base + extent_offset),
544                                 rc);
545                 goto out;
546         }
547         if (unlikely(ecryptfs_verbosity > 0)) {
548                 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
549                                 "with iv:\n");
550                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
551                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
552                                 "decryption:\n");
553                 ecryptfs_dump_hex((char *)
554                                   (page_address(enc_extent_page)
555                                    + (extent_offset * crypt_stat->extent_size)),
556                                   8);
557         }
558         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
559                                           (extent_offset
560                                            * crypt_stat->extent_size),
561                                           enc_extent_page, 0,
562                                           crypt_stat->extent_size, extent_iv);
563         if (rc < 0) {
564                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
565                        "page->index = [%ld], extent_offset = [%ld]; "
566                        "rc = [%d]\n", __func__, page->index, extent_offset,
567                        rc);
568                 goto out;
569         }
570         rc = 0;
571         if (unlikely(ecryptfs_verbosity > 0)) {
572                 ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16x]; "
573                                 "rc = [%d]\n", (extent_base + extent_offset),
574                                 rc);
575                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
576                                 "decryption:\n");
577                 ecryptfs_dump_hex((char *)(page_address(page)
578                                            + (extent_offset
579                                               * crypt_stat->extent_size)), 8);
580         }
581 out:
582         return rc;
583 }
584
585 /**
586  * ecryptfs_decrypt_page
587  * @page: Page mapped from the eCryptfs inode for the file; data read
588  *        and decrypted from the lower file will be written into this
589  *        page
590  *
591  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
592  * that eCryptfs pages may straddle the lower pages -- for instance,
593  * if the file was created on a machine with an 8K page size
594  * (resulting in an 8K header), and then the file is copied onto a
595  * host with a 32K page size, then when reading page 0 of the eCryptfs
596  * file, 24K of page 0 of the lower file will be read and decrypted,
597  * and then 8K of page 1 of the lower file will be read and decrypted.
598  *
599  * Returns zero on success; negative on error
600  */
601 int ecryptfs_decrypt_page(struct page *page)
602 {
603         struct inode *ecryptfs_inode;
604         struct ecryptfs_crypt_stat *crypt_stat;
605         char *enc_extent_virt;
606         struct page *enc_extent_page = NULL;
607         unsigned long extent_offset;
608         int rc = 0;
609
610         ecryptfs_inode = page->mapping->host;
611         crypt_stat =
612                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
613         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
614         enc_extent_page = alloc_page(GFP_USER);
615         if (!enc_extent_page) {
616                 rc = -ENOMEM;
617                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
618                                 "encrypted extent\n");
619                 goto out;
620         }
621         enc_extent_virt = kmap(enc_extent_page);
622         for (extent_offset = 0;
623              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
624              extent_offset++) {
625                 loff_t offset;
626
627                 ecryptfs_lower_offset_for_extent(
628                         &offset, ((page->index * (PAGE_CACHE_SIZE
629                                                   / crypt_stat->extent_size))
630                                   + extent_offset), crypt_stat);
631                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
632                                          crypt_stat->extent_size,
633                                          ecryptfs_inode);
634                 if (rc) {
635                         ecryptfs_printk(KERN_ERR, "Error attempting "
636                                         "to read lower page; rc = [%d]"
637                                         "\n", rc);
638                         goto out;
639                 }
640                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
641                                              extent_offset);
642                 if (rc) {
643                         printk(KERN_ERR "%s: Error encrypting extent; "
644                                "rc = [%d]\n", __func__, rc);
645                         goto out;
646                 }
647         }
648 out:
649         if (enc_extent_page) {
650                 kunmap(enc_extent_page);
651                 __free_page(enc_extent_page);
652         }
653         return rc;
654 }
655
656 /**
657  * decrypt_scatterlist
658  * @crypt_stat: Cryptographic context
659  * @dest_sg: The destination scatterlist to decrypt into
660  * @src_sg: The source scatterlist to decrypt from
661  * @size: The number of bytes to decrypt
662  * @iv: The initialization vector to use for the decryption
663  *
664  * Returns the number of bytes decrypted; negative value on error
665  */
666 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
667                                struct scatterlist *dest_sg,
668                                struct scatterlist *src_sg, int size,
669                                unsigned char *iv)
670 {
671         struct blkcipher_desc desc = {
672                 .tfm = crypt_stat->tfm,
673                 .info = iv,
674                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
675         };
676         int rc = 0;
677
678         /* Consider doing this once, when the file is opened */
679         mutex_lock(&crypt_stat->cs_tfm_mutex);
680         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
681                                      crypt_stat->key_size);
682         if (rc) {
683                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
684                                 rc);
685                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
686                 rc = -EINVAL;
687                 goto out;
688         }
689         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
690         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
691         mutex_unlock(&crypt_stat->cs_tfm_mutex);
692         if (rc) {
693                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
694                                 rc);
695                 goto out;
696         }
697         rc = size;
698 out:
699         return rc;
700 }
701
702 /**
703  * ecryptfs_encrypt_page_offset
704  * @crypt_stat: The cryptographic context
705  * @dst_page: The page to encrypt into
706  * @dst_offset: The offset in the page to encrypt into
707  * @src_page: The page to encrypt from
708  * @src_offset: The offset in the page to encrypt from
709  * @size: The number of bytes to encrypt
710  * @iv: The initialization vector to use for the encryption
711  *
712  * Returns the number of bytes encrypted
713  */
714 static int
715 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
716                              struct page *dst_page, int dst_offset,
717                              struct page *src_page, int src_offset, int size,
718                              unsigned char *iv)
719 {
720         struct scatterlist src_sg, dst_sg;
721
722         sg_init_table(&src_sg, 1);
723         sg_init_table(&dst_sg, 1);
724
725         sg_set_page(&src_sg, src_page, size, src_offset);
726         sg_set_page(&dst_sg, dst_page, size, dst_offset);
727         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
728 }
729
730 /**
731  * ecryptfs_decrypt_page_offset
732  * @crypt_stat: The cryptographic context
733  * @dst_page: The page to decrypt into
734  * @dst_offset: The offset in the page to decrypt into
735  * @src_page: The page to decrypt from
736  * @src_offset: The offset in the page to decrypt from
737  * @size: The number of bytes to decrypt
738  * @iv: The initialization vector to use for the decryption
739  *
740  * Returns the number of bytes decrypted
741  */
742 static int
743 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
744                              struct page *dst_page, int dst_offset,
745                              struct page *src_page, int src_offset, int size,
746                              unsigned char *iv)
747 {
748         struct scatterlist src_sg, dst_sg;
749
750         sg_init_table(&src_sg, 1);
751         sg_set_page(&src_sg, src_page, size, src_offset);
752
753         sg_init_table(&dst_sg, 1);
754         sg_set_page(&dst_sg, dst_page, size, dst_offset);
755
756         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
757 }
758
759 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
760
761 /**
762  * ecryptfs_init_crypt_ctx
763  * @crypt_stat: Uninitilized crypt stats structure
764  *
765  * Initialize the crypto context.
766  *
767  * TODO: Performance: Keep a cache of initialized cipher contexts;
768  * only init if needed
769  */
770 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
771 {
772         char *full_alg_name;
773         int rc = -EINVAL;
774
775         if (!crypt_stat->cipher) {
776                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
777                 goto out;
778         }
779         ecryptfs_printk(KERN_DEBUG,
780                         "Initializing cipher [%s]; strlen = [%d]; "
781                         "key_size_bits = [%d]\n",
782                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
783                         crypt_stat->key_size << 3);
784         if (crypt_stat->tfm) {
785                 rc = 0;
786                 goto out;
787         }
788         mutex_lock(&crypt_stat->cs_tfm_mutex);
789         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
790                                                     crypt_stat->cipher, "cbc");
791         if (rc)
792                 goto out_unlock;
793         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
794                                                  CRYPTO_ALG_ASYNC);
795         kfree(full_alg_name);
796         if (IS_ERR(crypt_stat->tfm)) {
797                 rc = PTR_ERR(crypt_stat->tfm);
798                 crypt_stat->tfm = NULL;
799                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
800                                 "Error initializing cipher [%s]\n",
801                                 crypt_stat->cipher);
802                 goto out_unlock;
803         }
804         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
805         rc = 0;
806 out_unlock:
807         mutex_unlock(&crypt_stat->cs_tfm_mutex);
808 out:
809         return rc;
810 }
811
812 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
813 {
814         int extent_size_tmp;
815
816         crypt_stat->extent_mask = 0xFFFFFFFF;
817         crypt_stat->extent_shift = 0;
818         if (crypt_stat->extent_size == 0)
819                 return;
820         extent_size_tmp = crypt_stat->extent_size;
821         while ((extent_size_tmp & 0x01) == 0) {
822                 extent_size_tmp >>= 1;
823                 crypt_stat->extent_mask <<= 1;
824                 crypt_stat->extent_shift++;
825         }
826 }
827
828 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
829 {
830         /* Default values; may be overwritten as we are parsing the
831          * packets. */
832         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
833         set_extent_mask_and_shift(crypt_stat);
834         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
835         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
836                 crypt_stat->num_header_bytes_at_front = 0;
837         else {
838                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
839                         crypt_stat->num_header_bytes_at_front =
840                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
841                 else
842                         crypt_stat->num_header_bytes_at_front = PAGE_CACHE_SIZE;
843         }
844 }
845
846 /**
847  * ecryptfs_compute_root_iv
848  * @crypt_stats
849  *
850  * On error, sets the root IV to all 0's.
851  */
852 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
853 {
854         int rc = 0;
855         char dst[MD5_DIGEST_SIZE];
856
857         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
858         BUG_ON(crypt_stat->iv_bytes <= 0);
859         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
860                 rc = -EINVAL;
861                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
862                                 "cannot generate root IV\n");
863                 goto out;
864         }
865         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
866                                     crypt_stat->key_size);
867         if (rc) {
868                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
869                                 "MD5 while generating root IV\n");
870                 goto out;
871         }
872         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
873 out:
874         if (rc) {
875                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
876                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
877         }
878         return rc;
879 }
880
881 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
882 {
883         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
884         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
885         ecryptfs_compute_root_iv(crypt_stat);
886         if (unlikely(ecryptfs_verbosity > 0)) {
887                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
888                 ecryptfs_dump_hex(crypt_stat->key,
889                                   crypt_stat->key_size);
890         }
891 }
892
893 /**
894  * ecryptfs_copy_mount_wide_flags_to_inode_flags
895  * @crypt_stat: The inode's cryptographic context
896  * @mount_crypt_stat: The mount point's cryptographic context
897  *
898  * This function propagates the mount-wide flags to individual inode
899  * flags.
900  */
901 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
902         struct ecryptfs_crypt_stat *crypt_stat,
903         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
904 {
905         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
906                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
907         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
908                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
909         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
910                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
911                 if (mount_crypt_stat->flags
912                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
913                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
914                 else if (mount_crypt_stat->flags
915                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
916                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
917         }
918 }
919
920 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
921         struct ecryptfs_crypt_stat *crypt_stat,
922         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
923 {
924         struct ecryptfs_global_auth_tok *global_auth_tok;
925         int rc = 0;
926
927         mutex_lock(&crypt_stat->keysig_list_mutex);
928         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
929
930         list_for_each_entry(global_auth_tok,
931                             &mount_crypt_stat->global_auth_tok_list,
932                             mount_crypt_stat_list) {
933                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
934                         continue;
935                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
936                 if (rc) {
937                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
938                         goto out;
939                 }
940         }
941
942 out:
943         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
944         mutex_unlock(&crypt_stat->keysig_list_mutex);
945         return rc;
946 }
947
948 /**
949  * ecryptfs_set_default_crypt_stat_vals
950  * @crypt_stat: The inode's cryptographic context
951  * @mount_crypt_stat: The mount point's cryptographic context
952  *
953  * Default values in the event that policy does not override them.
954  */
955 static void ecryptfs_set_default_crypt_stat_vals(
956         struct ecryptfs_crypt_stat *crypt_stat,
957         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
958 {
959         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
960                                                       mount_crypt_stat);
961         ecryptfs_set_default_sizes(crypt_stat);
962         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
963         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
964         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
965         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
966         crypt_stat->mount_crypt_stat = mount_crypt_stat;
967 }
968
969 /**
970  * ecryptfs_new_file_context
971  * @ecryptfs_dentry: The eCryptfs dentry
972  *
973  * If the crypto context for the file has not yet been established,
974  * this is where we do that.  Establishing a new crypto context
975  * involves the following decisions:
976  *  - What cipher to use?
977  *  - What set of authentication tokens to use?
978  * Here we just worry about getting enough information into the
979  * authentication tokens so that we know that they are available.
980  * We associate the available authentication tokens with the new file
981  * via the set of signatures in the crypt_stat struct.  Later, when
982  * the headers are actually written out, we may again defer to
983  * userspace to perform the encryption of the session key; for the
984  * foreseeable future, this will be the case with public key packets.
985  *
986  * Returns zero on success; non-zero otherwise
987  */
988 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
989 {
990         struct ecryptfs_crypt_stat *crypt_stat =
991             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
992         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
993             &ecryptfs_superblock_to_private(
994                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
995         int cipher_name_len;
996         int rc = 0;
997
998         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
999         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1000         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1001                                                       mount_crypt_stat);
1002         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1003                                                          mount_crypt_stat);
1004         if (rc) {
1005                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1006                        "to the inode key sigs; rc = [%d]\n", rc);
1007                 goto out;
1008         }
1009         cipher_name_len =
1010                 strlen(mount_crypt_stat->global_default_cipher_name);
1011         memcpy(crypt_stat->cipher,
1012                mount_crypt_stat->global_default_cipher_name,
1013                cipher_name_len);
1014         crypt_stat->cipher[cipher_name_len] = '\0';
1015         crypt_stat->key_size =
1016                 mount_crypt_stat->global_default_cipher_key_size;
1017         ecryptfs_generate_new_key(crypt_stat);
1018         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1019         if (rc)
1020                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1021                                 "context for cipher [%s]: rc = [%d]\n",
1022                                 crypt_stat->cipher, rc);
1023 out:
1024         return rc;
1025 }
1026
1027 /**
1028  * contains_ecryptfs_marker - check for the ecryptfs marker
1029  * @data: The data block in which to check
1030  *
1031  * Returns one if marker found; zero if not found
1032  */
1033 static int contains_ecryptfs_marker(char *data)
1034 {
1035         u32 m_1, m_2;
1036
1037         m_1 = get_unaligned_be32(data);
1038         m_2 = get_unaligned_be32(data + 4);
1039         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1040                 return 1;
1041         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1042                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1043                         MAGIC_ECRYPTFS_MARKER);
1044         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1045                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1046         return 0;
1047 }
1048
1049 struct ecryptfs_flag_map_elem {
1050         u32 file_flag;
1051         u32 local_flag;
1052 };
1053
1054 /* Add support for additional flags by adding elements here. */
1055 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1056         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1057         {0x00000002, ECRYPTFS_ENCRYPTED},
1058         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1059         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1060 };
1061
1062 /**
1063  * ecryptfs_process_flags
1064  * @crypt_stat: The cryptographic context
1065  * @page_virt: Source data to be parsed
1066  * @bytes_read: Updated with the number of bytes read
1067  *
1068  * Returns zero on success; non-zero if the flag set is invalid
1069  */
1070 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1071                                   char *page_virt, int *bytes_read)
1072 {
1073         int rc = 0;
1074         int i;
1075         u32 flags;
1076
1077         flags = get_unaligned_be32(page_virt);
1078         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1079                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1080                 if (flags & ecryptfs_flag_map[i].file_flag) {
1081                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1082                 } else
1083                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1084         /* Version is in top 8 bits of the 32-bit flag vector */
1085         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1086         (*bytes_read) = 4;
1087         return rc;
1088 }
1089
1090 /**
1091  * write_ecryptfs_marker
1092  * @page_virt: The pointer to in a page to begin writing the marker
1093  * @written: Number of bytes written
1094  *
1095  * Marker = 0x3c81b7f5
1096  */
1097 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1098 {
1099         u32 m_1, m_2;
1100
1101         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1102         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1103         put_unaligned_be32(m_1, page_virt);
1104         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1105         put_unaligned_be32(m_2, page_virt);
1106         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1107 }
1108
1109 static void
1110 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1111                      size_t *written)
1112 {
1113         u32 flags = 0;
1114         int i;
1115
1116         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1117                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1118                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1119                         flags |= ecryptfs_flag_map[i].file_flag;
1120         /* Version is in top 8 bits of the 32-bit flag vector */
1121         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1122         put_unaligned_be32(flags, page_virt);
1123         (*written) = 4;
1124 }
1125
1126 struct ecryptfs_cipher_code_str_map_elem {
1127         char cipher_str[16];
1128         u8 cipher_code;
1129 };
1130
1131 /* Add support for additional ciphers by adding elements here. The
1132  * cipher_code is whatever OpenPGP applicatoins use to identify the
1133  * ciphers. List in order of probability. */
1134 static struct ecryptfs_cipher_code_str_map_elem
1135 ecryptfs_cipher_code_str_map[] = {
1136         {"aes",RFC2440_CIPHER_AES_128 },
1137         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1138         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1139         {"cast5", RFC2440_CIPHER_CAST_5},
1140         {"twofish", RFC2440_CIPHER_TWOFISH},
1141         {"cast6", RFC2440_CIPHER_CAST_6},
1142         {"aes", RFC2440_CIPHER_AES_192},
1143         {"aes", RFC2440_CIPHER_AES_256}
1144 };
1145
1146 /**
1147  * ecryptfs_code_for_cipher_string
1148  * @cipher_name: The string alias for the cipher
1149  * @key_bytes: Length of key in bytes; used for AES code selection
1150  *
1151  * Returns zero on no match, or the cipher code on match
1152  */
1153 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1154 {
1155         int i;
1156         u8 code = 0;
1157         struct ecryptfs_cipher_code_str_map_elem *map =
1158                 ecryptfs_cipher_code_str_map;
1159
1160         if (strcmp(cipher_name, "aes") == 0) {
1161                 switch (key_bytes) {
1162                 case 16:
1163                         code = RFC2440_CIPHER_AES_128;
1164                         break;
1165                 case 24:
1166                         code = RFC2440_CIPHER_AES_192;
1167                         break;
1168                 case 32:
1169                         code = RFC2440_CIPHER_AES_256;
1170                 }
1171         } else {
1172                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1173                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1174                                 code = map[i].cipher_code;
1175                                 break;
1176                         }
1177         }
1178         return code;
1179 }
1180
1181 /**
1182  * ecryptfs_cipher_code_to_string
1183  * @str: Destination to write out the cipher name
1184  * @cipher_code: The code to convert to cipher name string
1185  *
1186  * Returns zero on success
1187  */
1188 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1189 {
1190         int rc = 0;
1191         int i;
1192
1193         str[0] = '\0';
1194         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1195                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1196                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1197         if (str[0] == '\0') {
1198                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1199                                 "[%d]\n", cipher_code);
1200                 rc = -EINVAL;
1201         }
1202         return rc;
1203 }
1204
1205 int ecryptfs_read_and_validate_header_region(char *data,
1206                                              struct inode *ecryptfs_inode)
1207 {
1208         struct ecryptfs_crypt_stat *crypt_stat =
1209                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
1210         int rc;
1211
1212         if (crypt_stat->extent_size == 0)
1213                 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
1214         rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
1215                                  ecryptfs_inode);
1216         if (rc) {
1217                 printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
1218                        __func__, rc);
1219                 goto out;
1220         }
1221         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) {
1222                 rc = -EINVAL;
1223         }
1224 out:
1225         return rc;
1226 }
1227
1228 void
1229 ecryptfs_write_header_metadata(char *virt,
1230                                struct ecryptfs_crypt_stat *crypt_stat,
1231                                size_t *written)
1232 {
1233         u32 header_extent_size;
1234         u16 num_header_extents_at_front;
1235
1236         header_extent_size = (u32)crypt_stat->extent_size;
1237         num_header_extents_at_front =
1238                 (u16)(crypt_stat->num_header_bytes_at_front
1239                       / crypt_stat->extent_size);
1240         put_unaligned_be32(header_extent_size, virt);
1241         virt += 4;
1242         put_unaligned_be16(num_header_extents_at_front, virt);
1243         (*written) = 6;
1244 }
1245
1246 struct kmem_cache *ecryptfs_header_cache_1;
1247 struct kmem_cache *ecryptfs_header_cache_2;
1248
1249 /**
1250  * ecryptfs_write_headers_virt
1251  * @page_virt: The virtual address to write the headers to
1252  * @max: The size of memory allocated at page_virt
1253  * @size: Set to the number of bytes written by this function
1254  * @crypt_stat: The cryptographic context
1255  * @ecryptfs_dentry: The eCryptfs dentry
1256  *
1257  * Format version: 1
1258  *
1259  *   Header Extent:
1260  *     Octets 0-7:        Unencrypted file size (big-endian)
1261  *     Octets 8-15:       eCryptfs special marker
1262  *     Octets 16-19:      Flags
1263  *      Octet 16:         File format version number (between 0 and 255)
1264  *      Octets 17-18:     Reserved
1265  *      Octet 19:         Bit 1 (lsb): Reserved
1266  *                        Bit 2: Encrypted?
1267  *                        Bits 3-8: Reserved
1268  *     Octets 20-23:      Header extent size (big-endian)
1269  *     Octets 24-25:      Number of header extents at front of file
1270  *                        (big-endian)
1271  *     Octet  26:         Begin RFC 2440 authentication token packet set
1272  *   Data Extent 0:
1273  *     Lower data (CBC encrypted)
1274  *   Data Extent 1:
1275  *     Lower data (CBC encrypted)
1276  *   ...
1277  *
1278  * Returns zero on success
1279  */
1280 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1281                                        size_t *size,
1282                                        struct ecryptfs_crypt_stat *crypt_stat,
1283                                        struct dentry *ecryptfs_dentry)
1284 {
1285         int rc;
1286         size_t written;
1287         size_t offset;
1288
1289         offset = ECRYPTFS_FILE_SIZE_BYTES;
1290         write_ecryptfs_marker((page_virt + offset), &written);
1291         offset += written;
1292         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1293         offset += written;
1294         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1295                                        &written);
1296         offset += written;
1297         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1298                                               ecryptfs_dentry, &written,
1299                                               max - offset);
1300         if (rc)
1301                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1302                                 "set; rc = [%d]\n", rc);
1303         if (size) {
1304                 offset += written;
1305                 *size = offset;
1306         }
1307         return rc;
1308 }
1309
1310 static int
1311 ecryptfs_write_metadata_to_contents(struct dentry *ecryptfs_dentry,
1312                                     char *virt, size_t virt_len)
1313 {
1314         int rc;
1315
1316         rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
1317                                   0, virt_len);
1318         if (rc)
1319                 printk(KERN_ERR "%s: Error attempting to write header "
1320                        "information to lower file; rc = [%d]\n", __func__,
1321                        rc);
1322         return rc;
1323 }
1324
1325 static int
1326 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1327                                  char *page_virt, size_t size)
1328 {
1329         int rc;
1330
1331         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1332                                size, 0);
1333         return rc;
1334 }
1335
1336 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1337                                                unsigned int order)
1338 {
1339         struct page *page;
1340
1341         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1342         if (page)
1343                 return (unsigned long) page_address(page);
1344         return 0;
1345 }
1346
1347 /**
1348  * ecryptfs_write_metadata
1349  * @ecryptfs_dentry: The eCryptfs dentry
1350  *
1351  * Write the file headers out.  This will likely involve a userspace
1352  * callout, in which the session key is encrypted with one or more
1353  * public keys and/or the passphrase necessary to do the encryption is
1354  * retrieved via a prompt.  Exactly what happens at this point should
1355  * be policy-dependent.
1356  *
1357  * Returns zero on success; non-zero on error
1358  */
1359 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
1360 {
1361         struct ecryptfs_crypt_stat *crypt_stat =
1362                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1363         unsigned int order;
1364         char *virt;
1365         size_t virt_len;
1366         size_t size = 0;
1367         int rc = 0;
1368
1369         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1370                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1371                         printk(KERN_ERR "Key is invalid; bailing out\n");
1372                         rc = -EINVAL;
1373                         goto out;
1374                 }
1375         } else {
1376                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1377                        __func__);
1378                 rc = -EINVAL;
1379                 goto out;
1380         }
1381         virt_len = crypt_stat->num_header_bytes_at_front;
1382         order = get_order(virt_len);
1383         /* Released in this function */
1384         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1385         if (!virt) {
1386                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1387                 rc = -ENOMEM;
1388                 goto out;
1389         }
1390         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1391                                          ecryptfs_dentry);
1392         if (unlikely(rc)) {
1393                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1394                        __func__, rc);
1395                 goto out_free;
1396         }
1397         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1398                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1399                                                       size);
1400         else
1401                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_dentry, virt,
1402                                                          virt_len);
1403         if (rc) {
1404                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1405                        "rc = [%d]\n", __func__, rc);
1406                 goto out_free;
1407         }
1408 out_free:
1409         free_pages((unsigned long)virt, order);
1410 out:
1411         return rc;
1412 }
1413
1414 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1415 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1416 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1417                                  char *virt, int *bytes_read,
1418                                  int validate_header_size)
1419 {
1420         int rc = 0;
1421         u32 header_extent_size;
1422         u16 num_header_extents_at_front;
1423
1424         header_extent_size = get_unaligned_be32(virt);
1425         virt += sizeof(__be32);
1426         num_header_extents_at_front = get_unaligned_be16(virt);
1427         crypt_stat->num_header_bytes_at_front =
1428                 (((size_t)num_header_extents_at_front
1429                   * (size_t)header_extent_size));
1430         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1431         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1432             && (crypt_stat->num_header_bytes_at_front
1433                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1434                 rc = -EINVAL;
1435                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1436                        crypt_stat->num_header_bytes_at_front);
1437         }
1438         return rc;
1439 }
1440
1441 /**
1442  * set_default_header_data
1443  * @crypt_stat: The cryptographic context
1444  *
1445  * For version 0 file format; this function is only for backwards
1446  * compatibility for files created with the prior versions of
1447  * eCryptfs.
1448  */
1449 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1450 {
1451         crypt_stat->num_header_bytes_at_front =
1452                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1453 }
1454
1455 /**
1456  * ecryptfs_read_headers_virt
1457  * @page_virt: The virtual address into which to read the headers
1458  * @crypt_stat: The cryptographic context
1459  * @ecryptfs_dentry: The eCryptfs dentry
1460  * @validate_header_size: Whether to validate the header size while reading
1461  *
1462  * Read/parse the header data. The header format is detailed in the
1463  * comment block for the ecryptfs_write_headers_virt() function.
1464  *
1465  * Returns zero on success
1466  */
1467 static int ecryptfs_read_headers_virt(char *page_virt,
1468                                       struct ecryptfs_crypt_stat *crypt_stat,
1469                                       struct dentry *ecryptfs_dentry,
1470                                       int validate_header_size)
1471 {
1472         int rc = 0;
1473         int offset;
1474         int bytes_read;
1475
1476         ecryptfs_set_default_sizes(crypt_stat);
1477         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1478                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1479         offset = ECRYPTFS_FILE_SIZE_BYTES;
1480         rc = contains_ecryptfs_marker(page_virt + offset);
1481         if (rc == 0) {
1482                 rc = -EINVAL;
1483                 goto out;
1484         }
1485         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1486         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1487                                     &bytes_read);
1488         if (rc) {
1489                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1490                 goto out;
1491         }
1492         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1493                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1494                                 "file version [%d] is supported by this "
1495                                 "version of eCryptfs\n",
1496                                 crypt_stat->file_version,
1497                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1498                 rc = -EINVAL;
1499                 goto out;
1500         }
1501         offset += bytes_read;
1502         if (crypt_stat->file_version >= 1) {
1503                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1504                                            &bytes_read, validate_header_size);
1505                 if (rc) {
1506                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1507                                         "metadata; rc = [%d]\n", rc);
1508                 }
1509                 offset += bytes_read;
1510         } else
1511                 set_default_header_data(crypt_stat);
1512         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1513                                        ecryptfs_dentry);
1514 out:
1515         return rc;
1516 }
1517
1518 /**
1519  * ecryptfs_read_xattr_region
1520  * @page_virt: The vitual address into which to read the xattr data
1521  * @ecryptfs_inode: The eCryptfs inode
1522  *
1523  * Attempts to read the crypto metadata from the extended attribute
1524  * region of the lower file.
1525  *
1526  * Returns zero on success; non-zero on error
1527  */
1528 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1529 {
1530         struct dentry *lower_dentry =
1531                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1532         ssize_t size;
1533         int rc = 0;
1534
1535         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1536                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1537         if (size < 0) {
1538                 if (unlikely(ecryptfs_verbosity > 0))
1539                         printk(KERN_INFO "Error attempting to read the [%s] "
1540                                "xattr from the lower file; return value = "
1541                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1542                 rc = -EINVAL;
1543                 goto out;
1544         }
1545 out:
1546         return rc;
1547 }
1548
1549 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1550                                             struct dentry *ecryptfs_dentry)
1551 {
1552         int rc;
1553
1554         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
1555         if (rc)
1556                 goto out;
1557         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1558                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1559                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1560                 rc = -EINVAL;
1561         }
1562 out:
1563         return rc;
1564 }
1565
1566 /**
1567  * ecryptfs_read_metadata
1568  *
1569  * Common entry point for reading file metadata. From here, we could
1570  * retrieve the header information from the header region of the file,
1571  * the xattr region of the file, or some other repostory that is
1572  * stored separately from the file itself. The current implementation
1573  * supports retrieving the metadata information from the file contents
1574  * and from the xattr region.
1575  *
1576  * Returns zero if valid headers found and parsed; non-zero otherwise
1577  */
1578 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1579 {
1580         int rc = 0;
1581         char *page_virt = NULL;
1582         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1583         struct ecryptfs_crypt_stat *crypt_stat =
1584             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1585         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1586                 &ecryptfs_superblock_to_private(
1587                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1588
1589         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1590                                                       mount_crypt_stat);
1591         /* Read the first page from the underlying file */
1592         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1593         if (!page_virt) {
1594                 rc = -ENOMEM;
1595                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1596                        __func__);
1597                 goto out;
1598         }
1599         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1600                                  ecryptfs_inode);
1601         if (!rc)
1602                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1603                                                 ecryptfs_dentry,
1604                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1605         if (rc) {
1606                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1607                 if (rc) {
1608                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1609                                "file header region or xattr region\n");
1610                         rc = -EINVAL;
1611                         goto out;
1612                 }
1613                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1614                                                 ecryptfs_dentry,
1615                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1616                 if (rc) {
1617                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1618                                "file xattr region either\n");
1619                         rc = -EINVAL;
1620                 }
1621                 if (crypt_stat->mount_crypt_stat->flags
1622                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1623                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1624                 } else {
1625                         printk(KERN_WARNING "Attempt to access file with "
1626                                "crypto metadata only in the extended attribute "
1627                                "region, but eCryptfs was mounted without "
1628                                "xattr support enabled. eCryptfs will not treat "
1629                                "this like an encrypted file.\n");
1630                         rc = -EINVAL;
1631                 }
1632         }
1633 out:
1634         if (page_virt) {
1635                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1636                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1637         }
1638         return rc;
1639 }
1640
1641 /**
1642  * ecryptfs_encrypt_filename - encrypt filename
1643  *
1644  * CBC-encrypts the filename. We do not want to encrypt the same
1645  * filename with the same key and IV, which may happen with hard
1646  * links, so we prepend random bits to each filename.
1647  *
1648  * Returns zero on success; non-zero otherwise
1649  */
1650 static int
1651 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1652                           struct ecryptfs_crypt_stat *crypt_stat,
1653                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1654 {
1655         int rc = 0;
1656
1657         filename->encrypted_filename = NULL;
1658         filename->encrypted_filename_size = 0;
1659         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1660             || (mount_crypt_stat && (mount_crypt_stat->flags
1661                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1662                 size_t packet_size;
1663                 size_t remaining_bytes;
1664
1665                 rc = ecryptfs_write_tag_70_packet(
1666                         NULL, NULL,
1667                         &filename->encrypted_filename_size,
1668                         mount_crypt_stat, NULL,
1669                         filename->filename_size);
1670                 if (rc) {
1671                         printk(KERN_ERR "%s: Error attempting to get packet "
1672                                "size for tag 72; rc = [%d]\n", __func__,
1673                                rc);
1674                         filename->encrypted_filename_size = 0;
1675                         goto out;
1676                 }
1677                 filename->encrypted_filename =
1678                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1679                 if (!filename->encrypted_filename) {
1680                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1681                                "to kmalloc [%zd] bytes\n", __func__,
1682                                filename->encrypted_filename_size);
1683                         rc = -ENOMEM;
1684                         goto out;
1685                 }
1686                 remaining_bytes = filename->encrypted_filename_size;
1687                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1688                                                   &remaining_bytes,
1689                                                   &packet_size,
1690                                                   mount_crypt_stat,
1691                                                   filename->filename,
1692                                                   filename->filename_size);
1693                 if (rc) {
1694                         printk(KERN_ERR "%s: Error attempting to generate "
1695                                "tag 70 packet; rc = [%d]\n", __func__,
1696                                rc);
1697                         kfree(filename->encrypted_filename);
1698                         filename->encrypted_filename = NULL;
1699                         filename->encrypted_filename_size = 0;
1700                         goto out;
1701                 }
1702                 filename->encrypted_filename_size = packet_size;
1703         } else {
1704                 printk(KERN_ERR "%s: No support for requested filename "
1705                        "encryption method in this release\n", __func__);
1706                 rc = -ENOTSUPP;
1707                 goto out;
1708         }
1709 out:
1710         return rc;
1711 }
1712
1713 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1714                                   const char *name, size_t name_size)
1715 {
1716         int rc = 0;
1717
1718         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1719         if (!(*copied_name)) {
1720                 rc = -ENOMEM;
1721                 goto out;
1722         }
1723         memcpy((void *)(*copied_name), (void *)name, name_size);
1724         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1725                                                  * in printing out the
1726                                                  * string in debug
1727                                                  * messages */
1728         (*copied_name_size) = name_size;
1729 out:
1730         return rc;
1731 }
1732
1733 /**
1734  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1735  * @key_tfm: Crypto context for key material, set by this function
1736  * @cipher_name: Name of the cipher
1737  * @key_size: Size of the key in bytes
1738  *
1739  * Returns zero on success. Any crypto_tfm structs allocated here
1740  * should be released by other functions, such as on a superblock put
1741  * event, regardless of whether this function succeeds for fails.
1742  */
1743 static int
1744 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1745                             char *cipher_name, size_t *key_size)
1746 {
1747         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1748         char *full_alg_name;
1749         int rc;
1750
1751         *key_tfm = NULL;
1752         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1753                 rc = -EINVAL;
1754                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1755                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1756                 goto out;
1757         }
1758         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1759                                                     "ecb");
1760         if (rc)
1761                 goto out;
1762         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1763         kfree(full_alg_name);
1764         if (IS_ERR(*key_tfm)) {
1765                 rc = PTR_ERR(*key_tfm);
1766                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1767                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1768                 goto out;
1769         }
1770         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1771         if (*key_size == 0) {
1772                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1773
1774                 *key_size = alg->max_keysize;
1775         }
1776         get_random_bytes(dummy_key, *key_size);
1777         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1778         if (rc) {
1779                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1780                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1781                        rc);
1782                 rc = -EINVAL;
1783                 goto out;
1784         }
1785 out:
1786         return rc;
1787 }
1788
1789 struct kmem_cache *ecryptfs_key_tfm_cache;
1790 static struct list_head key_tfm_list;
1791 struct mutex key_tfm_list_mutex;
1792
1793 int ecryptfs_init_crypto(void)
1794 {
1795         mutex_init(&key_tfm_list_mutex);
1796         INIT_LIST_HEAD(&key_tfm_list);
1797         return 0;
1798 }
1799
1800 /**
1801  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1802  *
1803  * Called only at module unload time
1804  */
1805 int ecryptfs_destroy_crypto(void)
1806 {
1807         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1808
1809         mutex_lock(&key_tfm_list_mutex);
1810         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1811                                  key_tfm_list) {
1812                 list_del(&key_tfm->key_tfm_list);
1813                 if (key_tfm->key_tfm)
1814                         crypto_free_blkcipher(key_tfm->key_tfm);
1815                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1816         }
1817         mutex_unlock(&key_tfm_list_mutex);
1818         return 0;
1819 }
1820
1821 int
1822 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1823                          size_t key_size)
1824 {
1825         struct ecryptfs_key_tfm *tmp_tfm;
1826         int rc = 0;
1827
1828         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1829
1830         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1831         if (key_tfm != NULL)
1832                 (*key_tfm) = tmp_tfm;
1833         if (!tmp_tfm) {
1834                 rc = -ENOMEM;
1835                 printk(KERN_ERR "Error attempting to allocate from "
1836                        "ecryptfs_key_tfm_cache\n");
1837                 goto out;
1838         }
1839         mutex_init(&tmp_tfm->key_tfm_mutex);
1840         strncpy(tmp_tfm->cipher_name, cipher_name,
1841                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1842         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1843         tmp_tfm->key_size = key_size;
1844         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1845                                          tmp_tfm->cipher_name,
1846                                          &tmp_tfm->key_size);
1847         if (rc) {
1848                 printk(KERN_ERR "Error attempting to initialize key TFM "
1849                        "cipher with name = [%s]; rc = [%d]\n",
1850                        tmp_tfm->cipher_name, rc);
1851                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1852                 if (key_tfm != NULL)
1853                         (*key_tfm) = NULL;
1854                 goto out;
1855         }
1856         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1857 out:
1858         return rc;
1859 }
1860
1861 /**
1862  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1863  * @cipher_name: the name of the cipher to search for
1864  * @key_tfm: set to corresponding tfm if found
1865  *
1866  * Searches for cached key_tfm matching @cipher_name
1867  * Must be called with &key_tfm_list_mutex held
1868  * Returns 1 if found, with @key_tfm set
1869  * Returns 0 if not found, with @key_tfm set to NULL
1870  */
1871 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1872 {
1873         struct ecryptfs_key_tfm *tmp_key_tfm;
1874
1875         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1876
1877         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1878                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1879                         if (key_tfm)
1880                                 (*key_tfm) = tmp_key_tfm;
1881                         return 1;
1882                 }
1883         }
1884         if (key_tfm)
1885                 (*key_tfm) = NULL;
1886         return 0;
1887 }
1888
1889 /**
1890  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1891  *
1892  * @tfm: set to cached tfm found, or new tfm created
1893  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1894  * @cipher_name: the name of the cipher to search for and/or add
1895  *
1896  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1897  * Searches for cached item first, and creates new if not found.
1898  * Returns 0 on success, non-zero if adding new cipher failed
1899  */
1900 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1901                                                struct mutex **tfm_mutex,
1902                                                char *cipher_name)
1903 {
1904         struct ecryptfs_key_tfm *key_tfm;
1905         int rc = 0;
1906
1907         (*tfm) = NULL;
1908         (*tfm_mutex) = NULL;
1909
1910         mutex_lock(&key_tfm_list_mutex);
1911         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1912                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1913                 if (rc) {
1914                         printk(KERN_ERR "Error adding new key_tfm to list; "
1915                                         "rc = [%d]\n", rc);
1916                         goto out;
1917                 }
1918         }
1919         (*tfm) = key_tfm->key_tfm;
1920         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1921 out:
1922         mutex_unlock(&key_tfm_list_mutex);
1923         return rc;
1924 }
1925
1926 /* 64 characters forming a 6-bit target field */
1927 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1928                                                  "EFGHIJKLMNOPQRST"
1929                                                  "UVWXYZabcdefghij"
1930                                                  "klmnopqrstuvwxyz");
1931
1932 /* We could either offset on every reverse map or just pad some 0x00's
1933  * at the front here */
1934 static const unsigned char filename_rev_map[] = {
1935         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1936         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1937         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1938         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1939         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1940         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1941         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1942         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1943         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1944         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1945         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1946         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1947         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1948         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1949         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1950         0x3D, 0x3E, 0x3F
1951 };
1952
1953 /**
1954  * ecryptfs_encode_for_filename
1955  * @dst: Destination location for encoded filename
1956  * @dst_size: Size of the encoded filename in bytes
1957  * @src: Source location for the filename to encode
1958  * @src_size: Size of the source in bytes
1959  */
1960 void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1961                                   unsigned char *src, size_t src_size)
1962 {
1963         size_t num_blocks;
1964         size_t block_num = 0;
1965         size_t dst_offset = 0;
1966         unsigned char last_block[3];
1967
1968         if (src_size == 0) {
1969                 (*dst_size) = 0;
1970                 goto out;
1971         }
1972         num_blocks = (src_size / 3);
1973         if ((src_size % 3) == 0) {
1974                 memcpy(last_block, (&src[src_size - 3]), 3);
1975         } else {
1976                 num_blocks++;
1977                 last_block[2] = 0x00;
1978                 switch (src_size % 3) {
1979                 case 1:
1980                         last_block[0] = src[src_size - 1];
1981                         last_block[1] = 0x00;
1982                         break;
1983                 case 2:
1984                         last_block[0] = src[src_size - 2];
1985                         last_block[1] = src[src_size - 1];
1986                 }
1987         }
1988         (*dst_size) = (num_blocks * 4);
1989         if (!dst)
1990                 goto out;
1991         while (block_num < num_blocks) {
1992                 unsigned char *src_block;
1993                 unsigned char dst_block[4];
1994
1995                 if (block_num == (num_blocks - 1))
1996                         src_block = last_block;
1997                 else
1998                         src_block = &src[block_num * 3];
1999                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
2000                 dst_block[1] = (((src_block[0] << 4) & 0x30)
2001                                 | ((src_block[1] >> 4) & 0x0F));
2002                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
2003                                 | ((src_block[2] >> 6) & 0x03));
2004                 dst_block[3] = (src_block[2] & 0x3F);
2005                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
2006                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
2007                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
2008                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
2009                 block_num++;
2010         }
2011 out:
2012         return;
2013 }
2014
2015 /**
2016  * ecryptfs_decode_from_filename
2017  * @dst: If NULL, this function only sets @dst_size and returns. If
2018  *       non-NULL, this function decodes the encoded octets in @src
2019  *       into the memory that @dst points to.
2020  * @dst_size: Set to the size of the decoded string.
2021  * @src: The encoded set of octets to decode.
2022  * @src_size: The size of the encoded set of octets to decode.
2023  */
2024 static void
2025 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2026                               const unsigned char *src, size_t src_size)
2027 {
2028         u8 current_bit_offset = 0;
2029         size_t src_byte_offset = 0;
2030         size_t dst_byte_offset = 0;
2031
2032         if (dst == NULL) {
2033                 /* Not exact; conservatively long. Every block of 4
2034                  * encoded characters decodes into a block of 3
2035                  * decoded characters. This segment of code provides
2036                  * the caller with the maximum amount of allocated
2037                  * space that @dst will need to point to in a
2038                  * subsequent call. */
2039                 (*dst_size) = (((src_size + 1) * 3) / 4);
2040                 goto out;
2041         }
2042         while (src_byte_offset < src_size) {
2043                 unsigned char src_byte =
2044                                 filename_rev_map[(int)src[src_byte_offset]];
2045
2046                 switch (current_bit_offset) {
2047                 case 0:
2048                         dst[dst_byte_offset] = (src_byte << 2);
2049                         current_bit_offset = 6;
2050                         break;
2051                 case 6:
2052                         dst[dst_byte_offset++] |= (src_byte >> 4);
2053                         dst[dst_byte_offset] = ((src_byte & 0xF)
2054                                                  << 4);
2055                         current_bit_offset = 4;
2056                         break;
2057                 case 4:
2058                         dst[dst_byte_offset++] |= (src_byte >> 2);
2059                         dst[dst_byte_offset] = (src_byte << 6);
2060                         current_bit_offset = 2;
2061                         break;
2062                 case 2:
2063                         dst[dst_byte_offset++] |= (src_byte);
2064                         dst[dst_byte_offset] = 0;
2065                         current_bit_offset = 0;
2066                         break;
2067                 }
2068                 src_byte_offset++;
2069         }
2070         (*dst_size) = dst_byte_offset;
2071 out:
2072         return;
2073 }
2074
2075 /**
2076  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2077  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2078  * @name: The plaintext name
2079  * @length: The length of the plaintext
2080  * @encoded_name: The encypted name
2081  *
2082  * Encrypts and encodes a filename into something that constitutes a
2083  * valid filename for a filesystem, with printable characters.
2084  *
2085  * We assume that we have a properly initialized crypto context,
2086  * pointed to by crypt_stat->tfm.
2087  *
2088  * Returns zero on success; non-zero on otherwise
2089  */
2090 int ecryptfs_encrypt_and_encode_filename(
2091         char **encoded_name,
2092         size_t *encoded_name_size,
2093         struct ecryptfs_crypt_stat *crypt_stat,
2094         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2095         const char *name, size_t name_size)
2096 {
2097         size_t encoded_name_no_prefix_size;
2098         int rc = 0;
2099
2100         (*encoded_name) = NULL;
2101         (*encoded_name_size) = 0;
2102         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2103             || (mount_crypt_stat && (mount_crypt_stat->flags
2104                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2105                 struct ecryptfs_filename *filename;
2106
2107                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2108                 if (!filename) {
2109                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2110                                "to kzalloc [%zd] bytes\n", __func__,
2111                                sizeof(*filename));
2112                         rc = -ENOMEM;
2113                         goto out;
2114                 }
2115                 filename->filename = (char *)name;
2116                 filename->filename_size = name_size;
2117                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2118                                                mount_crypt_stat);
2119                 if (rc) {
2120                         printk(KERN_ERR "%s: Error attempting to encrypt "
2121                                "filename; rc = [%d]\n", __func__, rc);
2122                         kfree(filename);
2123                         goto out;
2124                 }
2125                 ecryptfs_encode_for_filename(
2126                         NULL, &encoded_name_no_prefix_size,
2127                         filename->encrypted_filename,
2128                         filename->encrypted_filename_size);
2129                 if ((crypt_stat && (crypt_stat->flags
2130                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2131                     || (mount_crypt_stat
2132                         && (mount_crypt_stat->flags
2133                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2134                         (*encoded_name_size) =
2135                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2136                                  + encoded_name_no_prefix_size);
2137                 else
2138                         (*encoded_name_size) =
2139                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2140                                  + encoded_name_no_prefix_size);
2141                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2142                 if (!(*encoded_name)) {
2143                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2144                                "to kzalloc [%zd] bytes\n", __func__,
2145                                (*encoded_name_size));
2146                         rc = -ENOMEM;
2147                         kfree(filename->encrypted_filename);
2148                         kfree(filename);
2149                         goto out;
2150                 }
2151                 if ((crypt_stat && (crypt_stat->flags
2152                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2153                     || (mount_crypt_stat
2154                         && (mount_crypt_stat->flags
2155                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2156                         memcpy((*encoded_name),
2157                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2158                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2159                         ecryptfs_encode_for_filename(
2160                             ((*encoded_name)
2161                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2162                             &encoded_name_no_prefix_size,
2163                             filename->encrypted_filename,
2164                             filename->encrypted_filename_size);
2165                         (*encoded_name_size) =
2166                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2167                                  + encoded_name_no_prefix_size);
2168                         (*encoded_name)[(*encoded_name_size)] = '\0';
2169                         (*encoded_name_size)++;
2170                 } else {
2171                         rc = -ENOTSUPP;
2172                 }
2173                 if (rc) {
2174                         printk(KERN_ERR "%s: Error attempting to encode "
2175                                "encrypted filename; rc = [%d]\n", __func__,
2176                                rc);
2177                         kfree((*encoded_name));
2178                         (*encoded_name) = NULL;
2179                         (*encoded_name_size) = 0;
2180                 }
2181                 kfree(filename->encrypted_filename);
2182                 kfree(filename);
2183         } else {
2184                 rc = ecryptfs_copy_filename(encoded_name,
2185                                             encoded_name_size,
2186                                             name, name_size);
2187         }
2188 out:
2189         return rc;
2190 }
2191
2192 /**
2193  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2194  * @plaintext_name: The plaintext name
2195  * @plaintext_name_size: The plaintext name size
2196  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2197  * @name: The filename in cipher text
2198  * @name_size: The cipher text name size
2199  *
2200  * Decrypts and decodes the filename.
2201  *
2202  * Returns zero on error; non-zero otherwise
2203  */
2204 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2205                                          size_t *plaintext_name_size,
2206                                          struct dentry *ecryptfs_dir_dentry,
2207                                          const char *name, size_t name_size)
2208 {
2209         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2210                 &ecryptfs_superblock_to_private(
2211                         ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2212         char *decoded_name;
2213         size_t decoded_name_size;
2214         size_t packet_size;
2215         int rc = 0;
2216
2217         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2218             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2219             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2220             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2221                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2222                 const char *orig_name = name;
2223                 size_t orig_name_size = name_size;
2224
2225                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2226                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2227                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2228                                               name, name_size);
2229                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2230                 if (!decoded_name) {
2231                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2232                                "to kmalloc [%zd] bytes\n", __func__,
2233                                decoded_name_size);
2234                         rc = -ENOMEM;
2235                         goto out;
2236                 }
2237                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2238                                               name, name_size);
2239                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2240                                                   plaintext_name_size,
2241                                                   &packet_size,
2242                                                   mount_crypt_stat,
2243                                                   decoded_name,
2244                                                   decoded_name_size);
2245                 if (rc) {
2246                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2247                                "from filename; copying through filename "
2248                                "as-is\n", __func__);
2249                         rc = ecryptfs_copy_filename(plaintext_name,
2250                                                     plaintext_name_size,
2251                                                     orig_name, orig_name_size);
2252                         goto out_free;
2253                 }
2254         } else {
2255                 rc = ecryptfs_copy_filename(plaintext_name,
2256                                             plaintext_name_size,
2257                                             name, name_size);
2258                 goto out;
2259         }
2260 out_free:
2261         kfree(decoded_name);
2262 out:
2263         return rc;
2264 }