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[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 < 0) {
513                         ecryptfs_printk(KERN_ERR, "Error attempting "
514                                         "to write lower page; rc = [%d]"
515                                         "\n", rc);
516                         goto out;
517                 }
518         }
519         rc = 0;
520 out:
521         if (enc_extent_page) {
522                 kunmap(enc_extent_page);
523                 __free_page(enc_extent_page);
524         }
525         return rc;
526 }
527
528 static int ecryptfs_decrypt_extent(struct page *page,
529                                    struct ecryptfs_crypt_stat *crypt_stat,
530                                    struct page *enc_extent_page,
531                                    unsigned long extent_offset)
532 {
533         loff_t extent_base;
534         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
535         int rc;
536
537         extent_base = (((loff_t)page->index)
538                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
539         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
540                                 (extent_base + extent_offset));
541         if (rc) {
542                 ecryptfs_printk(KERN_ERR, "Error attempting to "
543                                 "derive IV for extent [0x%.16x]; "
544                                 "rc = [%d]\n", (extent_base + extent_offset),
545                                 rc);
546                 goto out;
547         }
548         if (unlikely(ecryptfs_verbosity > 0)) {
549                 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
550                                 "with iv:\n");
551                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
552                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
553                                 "decryption:\n");
554                 ecryptfs_dump_hex((char *)
555                                   (page_address(enc_extent_page)
556                                    + (extent_offset * crypt_stat->extent_size)),
557                                   8);
558         }
559         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
560                                           (extent_offset
561                                            * crypt_stat->extent_size),
562                                           enc_extent_page, 0,
563                                           crypt_stat->extent_size, extent_iv);
564         if (rc < 0) {
565                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
566                        "page->index = [%ld], extent_offset = [%ld]; "
567                        "rc = [%d]\n", __func__, page->index, extent_offset,
568                        rc);
569                 goto out;
570         }
571         rc = 0;
572         if (unlikely(ecryptfs_verbosity > 0)) {
573                 ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16x]; "
574                                 "rc = [%d]\n", (extent_base + extent_offset),
575                                 rc);
576                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
577                                 "decryption:\n");
578                 ecryptfs_dump_hex((char *)(page_address(page)
579                                            + (extent_offset
580                                               * crypt_stat->extent_size)), 8);
581         }
582 out:
583         return rc;
584 }
585
586 /**
587  * ecryptfs_decrypt_page
588  * @page: Page mapped from the eCryptfs inode for the file; data read
589  *        and decrypted from the lower file will be written into this
590  *        page
591  *
592  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
593  * that eCryptfs pages may straddle the lower pages -- for instance,
594  * if the file was created on a machine with an 8K page size
595  * (resulting in an 8K header), and then the file is copied onto a
596  * host with a 32K page size, then when reading page 0 of the eCryptfs
597  * file, 24K of page 0 of the lower file will be read and decrypted,
598  * and then 8K of page 1 of the lower file will be read and decrypted.
599  *
600  * Returns zero on success; negative on error
601  */
602 int ecryptfs_decrypt_page(struct page *page)
603 {
604         struct inode *ecryptfs_inode;
605         struct ecryptfs_crypt_stat *crypt_stat;
606         char *enc_extent_virt;
607         struct page *enc_extent_page = NULL;
608         unsigned long extent_offset;
609         int rc = 0;
610
611         ecryptfs_inode = page->mapping->host;
612         crypt_stat =
613                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
614         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
615         enc_extent_page = alloc_page(GFP_USER);
616         if (!enc_extent_page) {
617                 rc = -ENOMEM;
618                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
619                                 "encrypted extent\n");
620                 goto out;
621         }
622         enc_extent_virt = kmap(enc_extent_page);
623         for (extent_offset = 0;
624              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
625              extent_offset++) {
626                 loff_t offset;
627
628                 ecryptfs_lower_offset_for_extent(
629                         &offset, ((page->index * (PAGE_CACHE_SIZE
630                                                   / crypt_stat->extent_size))
631                                   + extent_offset), crypt_stat);
632                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
633                                          crypt_stat->extent_size,
634                                          ecryptfs_inode);
635                 if (rc < 0) {
636                         ecryptfs_printk(KERN_ERR, "Error attempting "
637                                         "to read lower page; rc = [%d]"
638                                         "\n", rc);
639                         goto out;
640                 }
641                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
642                                              extent_offset);
643                 if (rc) {
644                         printk(KERN_ERR "%s: Error encrypting extent; "
645                                "rc = [%d]\n", __func__, rc);
646                         goto out;
647                 }
648         }
649 out:
650         if (enc_extent_page) {
651                 kunmap(enc_extent_page);
652                 __free_page(enc_extent_page);
653         }
654         return rc;
655 }
656
657 /**
658  * decrypt_scatterlist
659  * @crypt_stat: Cryptographic context
660  * @dest_sg: The destination scatterlist to decrypt into
661  * @src_sg: The source scatterlist to decrypt from
662  * @size: The number of bytes to decrypt
663  * @iv: The initialization vector to use for the decryption
664  *
665  * Returns the number of bytes decrypted; negative value on error
666  */
667 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
668                                struct scatterlist *dest_sg,
669                                struct scatterlist *src_sg, int size,
670                                unsigned char *iv)
671 {
672         struct blkcipher_desc desc = {
673                 .tfm = crypt_stat->tfm,
674                 .info = iv,
675                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
676         };
677         int rc = 0;
678
679         /* Consider doing this once, when the file is opened */
680         mutex_lock(&crypt_stat->cs_tfm_mutex);
681         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
682                                      crypt_stat->key_size);
683         if (rc) {
684                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
685                                 rc);
686                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
687                 rc = -EINVAL;
688                 goto out;
689         }
690         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
691         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
692         mutex_unlock(&crypt_stat->cs_tfm_mutex);
693         if (rc) {
694                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
695                                 rc);
696                 goto out;
697         }
698         rc = size;
699 out:
700         return rc;
701 }
702
703 /**
704  * ecryptfs_encrypt_page_offset
705  * @crypt_stat: The cryptographic context
706  * @dst_page: The page to encrypt into
707  * @dst_offset: The offset in the page to encrypt into
708  * @src_page: The page to encrypt from
709  * @src_offset: The offset in the page to encrypt from
710  * @size: The number of bytes to encrypt
711  * @iv: The initialization vector to use for the encryption
712  *
713  * Returns the number of bytes encrypted
714  */
715 static int
716 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
717                              struct page *dst_page, int dst_offset,
718                              struct page *src_page, int src_offset, int size,
719                              unsigned char *iv)
720 {
721         struct scatterlist src_sg, dst_sg;
722
723         sg_init_table(&src_sg, 1);
724         sg_init_table(&dst_sg, 1);
725
726         sg_set_page(&src_sg, src_page, size, src_offset);
727         sg_set_page(&dst_sg, dst_page, size, dst_offset);
728         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
729 }
730
731 /**
732  * ecryptfs_decrypt_page_offset
733  * @crypt_stat: The cryptographic context
734  * @dst_page: The page to decrypt into
735  * @dst_offset: The offset in the page to decrypt into
736  * @src_page: The page to decrypt from
737  * @src_offset: The offset in the page to decrypt from
738  * @size: The number of bytes to decrypt
739  * @iv: The initialization vector to use for the decryption
740  *
741  * Returns the number of bytes decrypted
742  */
743 static int
744 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
745                              struct page *dst_page, int dst_offset,
746                              struct page *src_page, int src_offset, int size,
747                              unsigned char *iv)
748 {
749         struct scatterlist src_sg, dst_sg;
750
751         sg_init_table(&src_sg, 1);
752         sg_set_page(&src_sg, src_page, size, src_offset);
753
754         sg_init_table(&dst_sg, 1);
755         sg_set_page(&dst_sg, dst_page, size, dst_offset);
756
757         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
758 }
759
760 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
761
762 /**
763  * ecryptfs_init_crypt_ctx
764  * @crypt_stat: Uninitilized crypt stats structure
765  *
766  * Initialize the crypto context.
767  *
768  * TODO: Performance: Keep a cache of initialized cipher contexts;
769  * only init if needed
770  */
771 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
772 {
773         char *full_alg_name;
774         int rc = -EINVAL;
775
776         if (!crypt_stat->cipher) {
777                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
778                 goto out;
779         }
780         ecryptfs_printk(KERN_DEBUG,
781                         "Initializing cipher [%s]; strlen = [%d]; "
782                         "key_size_bits = [%d]\n",
783                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
784                         crypt_stat->key_size << 3);
785         if (crypt_stat->tfm) {
786                 rc = 0;
787                 goto out;
788         }
789         mutex_lock(&crypt_stat->cs_tfm_mutex);
790         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
791                                                     crypt_stat->cipher, "cbc");
792         if (rc)
793                 goto out_unlock;
794         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
795                                                  CRYPTO_ALG_ASYNC);
796         kfree(full_alg_name);
797         if (IS_ERR(crypt_stat->tfm)) {
798                 rc = PTR_ERR(crypt_stat->tfm);
799                 crypt_stat->tfm = NULL;
800                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
801                                 "Error initializing cipher [%s]\n",
802                                 crypt_stat->cipher);
803                 goto out_unlock;
804         }
805         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
806         rc = 0;
807 out_unlock:
808         mutex_unlock(&crypt_stat->cs_tfm_mutex);
809 out:
810         return rc;
811 }
812
813 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
814 {
815         int extent_size_tmp;
816
817         crypt_stat->extent_mask = 0xFFFFFFFF;
818         crypt_stat->extent_shift = 0;
819         if (crypt_stat->extent_size == 0)
820                 return;
821         extent_size_tmp = crypt_stat->extent_size;
822         while ((extent_size_tmp & 0x01) == 0) {
823                 extent_size_tmp >>= 1;
824                 crypt_stat->extent_mask <<= 1;
825                 crypt_stat->extent_shift++;
826         }
827 }
828
829 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
830 {
831         /* Default values; may be overwritten as we are parsing the
832          * packets. */
833         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
834         set_extent_mask_and_shift(crypt_stat);
835         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
836         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
837                 crypt_stat->num_header_bytes_at_front = 0;
838         else {
839                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
840                         crypt_stat->num_header_bytes_at_front =
841                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
842                 else
843                         crypt_stat->num_header_bytes_at_front = PAGE_CACHE_SIZE;
844         }
845 }
846
847 /**
848  * ecryptfs_compute_root_iv
849  * @crypt_stats
850  *
851  * On error, sets the root IV to all 0's.
852  */
853 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
854 {
855         int rc = 0;
856         char dst[MD5_DIGEST_SIZE];
857
858         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
859         BUG_ON(crypt_stat->iv_bytes <= 0);
860         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
861                 rc = -EINVAL;
862                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
863                                 "cannot generate root IV\n");
864                 goto out;
865         }
866         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
867                                     crypt_stat->key_size);
868         if (rc) {
869                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
870                                 "MD5 while generating root IV\n");
871                 goto out;
872         }
873         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
874 out:
875         if (rc) {
876                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
877                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
878         }
879         return rc;
880 }
881
882 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
883 {
884         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
885         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
886         ecryptfs_compute_root_iv(crypt_stat);
887         if (unlikely(ecryptfs_verbosity > 0)) {
888                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
889                 ecryptfs_dump_hex(crypt_stat->key,
890                                   crypt_stat->key_size);
891         }
892 }
893
894 /**
895  * ecryptfs_copy_mount_wide_flags_to_inode_flags
896  * @crypt_stat: The inode's cryptographic context
897  * @mount_crypt_stat: The mount point's cryptographic context
898  *
899  * This function propagates the mount-wide flags to individual inode
900  * flags.
901  */
902 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
903         struct ecryptfs_crypt_stat *crypt_stat,
904         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
905 {
906         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
907                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
908         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
909                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
910         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
911                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
912                 if (mount_crypt_stat->flags
913                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
914                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
915                 else if (mount_crypt_stat->flags
916                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
917                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
918         }
919 }
920
921 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
922         struct ecryptfs_crypt_stat *crypt_stat,
923         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
924 {
925         struct ecryptfs_global_auth_tok *global_auth_tok;
926         int rc = 0;
927
928         mutex_lock(&crypt_stat->keysig_list_mutex);
929         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
930
931         list_for_each_entry(global_auth_tok,
932                             &mount_crypt_stat->global_auth_tok_list,
933                             mount_crypt_stat_list) {
934                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
935                         continue;
936                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
937                 if (rc) {
938                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
939                         goto out;
940                 }
941         }
942
943 out:
944         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
945         mutex_unlock(&crypt_stat->keysig_list_mutex);
946         return rc;
947 }
948
949 /**
950  * ecryptfs_set_default_crypt_stat_vals
951  * @crypt_stat: The inode's cryptographic context
952  * @mount_crypt_stat: The mount point's cryptographic context
953  *
954  * Default values in the event that policy does not override them.
955  */
956 static void ecryptfs_set_default_crypt_stat_vals(
957         struct ecryptfs_crypt_stat *crypt_stat,
958         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
959 {
960         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
961                                                       mount_crypt_stat);
962         ecryptfs_set_default_sizes(crypt_stat);
963         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
964         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
965         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
966         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
967         crypt_stat->mount_crypt_stat = mount_crypt_stat;
968 }
969
970 /**
971  * ecryptfs_new_file_context
972  * @ecryptfs_dentry: The eCryptfs dentry
973  *
974  * If the crypto context for the file has not yet been established,
975  * this is where we do that.  Establishing a new crypto context
976  * involves the following decisions:
977  *  - What cipher to use?
978  *  - What set of authentication tokens to use?
979  * Here we just worry about getting enough information into the
980  * authentication tokens so that we know that they are available.
981  * We associate the available authentication tokens with the new file
982  * via the set of signatures in the crypt_stat struct.  Later, when
983  * the headers are actually written out, we may again defer to
984  * userspace to perform the encryption of the session key; for the
985  * foreseeable future, this will be the case with public key packets.
986  *
987  * Returns zero on success; non-zero otherwise
988  */
989 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
990 {
991         struct ecryptfs_crypt_stat *crypt_stat =
992             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
993         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
994             &ecryptfs_superblock_to_private(
995                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
996         int cipher_name_len;
997         int rc = 0;
998
999         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
1000         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1001         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1002                                                       mount_crypt_stat);
1003         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1004                                                          mount_crypt_stat);
1005         if (rc) {
1006                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1007                        "to the inode key sigs; rc = [%d]\n", rc);
1008                 goto out;
1009         }
1010         cipher_name_len =
1011                 strlen(mount_crypt_stat->global_default_cipher_name);
1012         memcpy(crypt_stat->cipher,
1013                mount_crypt_stat->global_default_cipher_name,
1014                cipher_name_len);
1015         crypt_stat->cipher[cipher_name_len] = '\0';
1016         crypt_stat->key_size =
1017                 mount_crypt_stat->global_default_cipher_key_size;
1018         ecryptfs_generate_new_key(crypt_stat);
1019         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1020         if (rc)
1021                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1022                                 "context for cipher [%s]: rc = [%d]\n",
1023                                 crypt_stat->cipher, rc);
1024 out:
1025         return rc;
1026 }
1027
1028 /**
1029  * contains_ecryptfs_marker - check for the ecryptfs marker
1030  * @data: The data block in which to check
1031  *
1032  * Returns one if marker found; zero if not found
1033  */
1034 static int contains_ecryptfs_marker(char *data)
1035 {
1036         u32 m_1, m_2;
1037
1038         m_1 = get_unaligned_be32(data);
1039         m_2 = get_unaligned_be32(data + 4);
1040         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1041                 return 1;
1042         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1043                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1044                         MAGIC_ECRYPTFS_MARKER);
1045         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1046                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1047         return 0;
1048 }
1049
1050 struct ecryptfs_flag_map_elem {
1051         u32 file_flag;
1052         u32 local_flag;
1053 };
1054
1055 /* Add support for additional flags by adding elements here. */
1056 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1057         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1058         {0x00000002, ECRYPTFS_ENCRYPTED},
1059         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1060         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1061 };
1062
1063 /**
1064  * ecryptfs_process_flags
1065  * @crypt_stat: The cryptographic context
1066  * @page_virt: Source data to be parsed
1067  * @bytes_read: Updated with the number of bytes read
1068  *
1069  * Returns zero on success; non-zero if the flag set is invalid
1070  */
1071 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1072                                   char *page_virt, int *bytes_read)
1073 {
1074         int rc = 0;
1075         int i;
1076         u32 flags;
1077
1078         flags = get_unaligned_be32(page_virt);
1079         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1080                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1081                 if (flags & ecryptfs_flag_map[i].file_flag) {
1082                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1083                 } else
1084                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1085         /* Version is in top 8 bits of the 32-bit flag vector */
1086         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1087         (*bytes_read) = 4;
1088         return rc;
1089 }
1090
1091 /**
1092  * write_ecryptfs_marker
1093  * @page_virt: The pointer to in a page to begin writing the marker
1094  * @written: Number of bytes written
1095  *
1096  * Marker = 0x3c81b7f5
1097  */
1098 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1099 {
1100         u32 m_1, m_2;
1101
1102         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1103         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1104         put_unaligned_be32(m_1, page_virt);
1105         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1106         put_unaligned_be32(m_2, page_virt);
1107         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1108 }
1109
1110 static void
1111 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1112                      size_t *written)
1113 {
1114         u32 flags = 0;
1115         int i;
1116
1117         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1118                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1119                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1120                         flags |= ecryptfs_flag_map[i].file_flag;
1121         /* Version is in top 8 bits of the 32-bit flag vector */
1122         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1123         put_unaligned_be32(flags, page_virt);
1124         (*written) = 4;
1125 }
1126
1127 struct ecryptfs_cipher_code_str_map_elem {
1128         char cipher_str[16];
1129         u8 cipher_code;
1130 };
1131
1132 /* Add support for additional ciphers by adding elements here. The
1133  * cipher_code is whatever OpenPGP applicatoins use to identify the
1134  * ciphers. List in order of probability. */
1135 static struct ecryptfs_cipher_code_str_map_elem
1136 ecryptfs_cipher_code_str_map[] = {
1137         {"aes",RFC2440_CIPHER_AES_128 },
1138         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1139         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1140         {"cast5", RFC2440_CIPHER_CAST_5},
1141         {"twofish", RFC2440_CIPHER_TWOFISH},
1142         {"cast6", RFC2440_CIPHER_CAST_6},
1143         {"aes", RFC2440_CIPHER_AES_192},
1144         {"aes", RFC2440_CIPHER_AES_256}
1145 };
1146
1147 /**
1148  * ecryptfs_code_for_cipher_string
1149  * @cipher_name: The string alias for the cipher
1150  * @key_bytes: Length of key in bytes; used for AES code selection
1151  *
1152  * Returns zero on no match, or the cipher code on match
1153  */
1154 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1155 {
1156         int i;
1157         u8 code = 0;
1158         struct ecryptfs_cipher_code_str_map_elem *map =
1159                 ecryptfs_cipher_code_str_map;
1160
1161         if (strcmp(cipher_name, "aes") == 0) {
1162                 switch (key_bytes) {
1163                 case 16:
1164                         code = RFC2440_CIPHER_AES_128;
1165                         break;
1166                 case 24:
1167                         code = RFC2440_CIPHER_AES_192;
1168                         break;
1169                 case 32:
1170                         code = RFC2440_CIPHER_AES_256;
1171                 }
1172         } else {
1173                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1174                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1175                                 code = map[i].cipher_code;
1176                                 break;
1177                         }
1178         }
1179         return code;
1180 }
1181
1182 /**
1183  * ecryptfs_cipher_code_to_string
1184  * @str: Destination to write out the cipher name
1185  * @cipher_code: The code to convert to cipher name string
1186  *
1187  * Returns zero on success
1188  */
1189 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1190 {
1191         int rc = 0;
1192         int i;
1193
1194         str[0] = '\0';
1195         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1196                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1197                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1198         if (str[0] == '\0') {
1199                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1200                                 "[%d]\n", cipher_code);
1201                 rc = -EINVAL;
1202         }
1203         return rc;
1204 }
1205
1206 int ecryptfs_read_and_validate_header_region(char *data,
1207                                              struct inode *ecryptfs_inode)
1208 {
1209         struct ecryptfs_crypt_stat *crypt_stat =
1210                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
1211         int rc;
1212
1213         if (crypt_stat->extent_size == 0)
1214                 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
1215         rc = ecryptfs_read_lower(data, 0, crypt_stat->extent_size,
1216                                  ecryptfs_inode);
1217         if (rc < 0) {
1218                 printk(KERN_ERR "%s: Error reading header region; rc = [%d]\n",
1219                        __func__, rc);
1220                 goto out;
1221         }
1222         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) {
1223                 rc = -EINVAL;
1224         } else
1225                 rc = 0;
1226 out:
1227         return rc;
1228 }
1229
1230 void
1231 ecryptfs_write_header_metadata(char *virt,
1232                                struct ecryptfs_crypt_stat *crypt_stat,
1233                                size_t *written)
1234 {
1235         u32 header_extent_size;
1236         u16 num_header_extents_at_front;
1237
1238         header_extent_size = (u32)crypt_stat->extent_size;
1239         num_header_extents_at_front =
1240                 (u16)(crypt_stat->num_header_bytes_at_front
1241                       / crypt_stat->extent_size);
1242         put_unaligned_be32(header_extent_size, virt);
1243         virt += 4;
1244         put_unaligned_be16(num_header_extents_at_front, virt);
1245         (*written) = 6;
1246 }
1247
1248 struct kmem_cache *ecryptfs_header_cache_1;
1249 struct kmem_cache *ecryptfs_header_cache_2;
1250
1251 /**
1252  * ecryptfs_write_headers_virt
1253  * @page_virt: The virtual address to write the headers to
1254  * @max: The size of memory allocated at page_virt
1255  * @size: Set to the number of bytes written by this function
1256  * @crypt_stat: The cryptographic context
1257  * @ecryptfs_dentry: The eCryptfs dentry
1258  *
1259  * Format version: 1
1260  *
1261  *   Header Extent:
1262  *     Octets 0-7:        Unencrypted file size (big-endian)
1263  *     Octets 8-15:       eCryptfs special marker
1264  *     Octets 16-19:      Flags
1265  *      Octet 16:         File format version number (between 0 and 255)
1266  *      Octets 17-18:     Reserved
1267  *      Octet 19:         Bit 1 (lsb): Reserved
1268  *                        Bit 2: Encrypted?
1269  *                        Bits 3-8: Reserved
1270  *     Octets 20-23:      Header extent size (big-endian)
1271  *     Octets 24-25:      Number of header extents at front of file
1272  *                        (big-endian)
1273  *     Octet  26:         Begin RFC 2440 authentication token packet set
1274  *   Data Extent 0:
1275  *     Lower data (CBC encrypted)
1276  *   Data Extent 1:
1277  *     Lower data (CBC encrypted)
1278  *   ...
1279  *
1280  * Returns zero on success
1281  */
1282 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1283                                        size_t *size,
1284                                        struct ecryptfs_crypt_stat *crypt_stat,
1285                                        struct dentry *ecryptfs_dentry)
1286 {
1287         int rc;
1288         size_t written;
1289         size_t offset;
1290
1291         offset = ECRYPTFS_FILE_SIZE_BYTES;
1292         write_ecryptfs_marker((page_virt + offset), &written);
1293         offset += written;
1294         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1295         offset += written;
1296         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1297                                        &written);
1298         offset += written;
1299         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1300                                               ecryptfs_dentry, &written,
1301                                               max - offset);
1302         if (rc)
1303                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1304                                 "set; rc = [%d]\n", rc);
1305         if (size) {
1306                 offset += written;
1307                 *size = offset;
1308         }
1309         return rc;
1310 }
1311
1312 static int
1313 ecryptfs_write_metadata_to_contents(struct dentry *ecryptfs_dentry,
1314                                     char *virt, size_t virt_len)
1315 {
1316         int rc;
1317
1318         rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
1319                                   0, virt_len);
1320         if (rc < 0)
1321                 printk(KERN_ERR "%s: Error attempting to write header "
1322                        "information to lower file; rc = [%d]\n", __func__, rc);
1323         else
1324                 rc = 0;
1325         return rc;
1326 }
1327
1328 static int
1329 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1330                                  char *page_virt, size_t size)
1331 {
1332         int rc;
1333
1334         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1335                                size, 0);
1336         return rc;
1337 }
1338
1339 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1340                                                unsigned int order)
1341 {
1342         struct page *page;
1343
1344         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1345         if (page)
1346                 return (unsigned long) page_address(page);
1347         return 0;
1348 }
1349
1350 /**
1351  * ecryptfs_write_metadata
1352  * @ecryptfs_dentry: The eCryptfs dentry
1353  *
1354  * Write the file headers out.  This will likely involve a userspace
1355  * callout, in which the session key is encrypted with one or more
1356  * public keys and/or the passphrase necessary to do the encryption is
1357  * retrieved via a prompt.  Exactly what happens at this point should
1358  * be policy-dependent.
1359  *
1360  * Returns zero on success; non-zero on error
1361  */
1362 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
1363 {
1364         struct ecryptfs_crypt_stat *crypt_stat =
1365                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1366         unsigned int order;
1367         char *virt;
1368         size_t virt_len;
1369         size_t size = 0;
1370         int rc = 0;
1371
1372         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1373                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1374                         printk(KERN_ERR "Key is invalid; bailing out\n");
1375                         rc = -EINVAL;
1376                         goto out;
1377                 }
1378         } else {
1379                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1380                        __func__);
1381                 rc = -EINVAL;
1382                 goto out;
1383         }
1384         virt_len = crypt_stat->num_header_bytes_at_front;
1385         order = get_order(virt_len);
1386         /* Released in this function */
1387         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1388         if (!virt) {
1389                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1390                 rc = -ENOMEM;
1391                 goto out;
1392         }
1393         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1394                                          ecryptfs_dentry);
1395         if (unlikely(rc)) {
1396                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1397                        __func__, rc);
1398                 goto out_free;
1399         }
1400         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1401                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1402                                                       size);
1403         else
1404                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_dentry, virt,
1405                                                          virt_len);
1406         if (rc) {
1407                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1408                        "rc = [%d]\n", __func__, rc);
1409                 goto out_free;
1410         }
1411 out_free:
1412         free_pages((unsigned long)virt, order);
1413 out:
1414         return rc;
1415 }
1416
1417 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1418 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1419 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1420                                  char *virt, int *bytes_read,
1421                                  int validate_header_size)
1422 {
1423         int rc = 0;
1424         u32 header_extent_size;
1425         u16 num_header_extents_at_front;
1426
1427         header_extent_size = get_unaligned_be32(virt);
1428         virt += sizeof(__be32);
1429         num_header_extents_at_front = get_unaligned_be16(virt);
1430         crypt_stat->num_header_bytes_at_front =
1431                 (((size_t)num_header_extents_at_front
1432                   * (size_t)header_extent_size));
1433         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1434         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1435             && (crypt_stat->num_header_bytes_at_front
1436                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1437                 rc = -EINVAL;
1438                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1439                        crypt_stat->num_header_bytes_at_front);
1440         }
1441         return rc;
1442 }
1443
1444 /**
1445  * set_default_header_data
1446  * @crypt_stat: The cryptographic context
1447  *
1448  * For version 0 file format; this function is only for backwards
1449  * compatibility for files created with the prior versions of
1450  * eCryptfs.
1451  */
1452 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1453 {
1454         crypt_stat->num_header_bytes_at_front =
1455                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1456 }
1457
1458 /**
1459  * ecryptfs_read_headers_virt
1460  * @page_virt: The virtual address into which to read the headers
1461  * @crypt_stat: The cryptographic context
1462  * @ecryptfs_dentry: The eCryptfs dentry
1463  * @validate_header_size: Whether to validate the header size while reading
1464  *
1465  * Read/parse the header data. The header format is detailed in the
1466  * comment block for the ecryptfs_write_headers_virt() function.
1467  *
1468  * Returns zero on success
1469  */
1470 static int ecryptfs_read_headers_virt(char *page_virt,
1471                                       struct ecryptfs_crypt_stat *crypt_stat,
1472                                       struct dentry *ecryptfs_dentry,
1473                                       int validate_header_size)
1474 {
1475         int rc = 0;
1476         int offset;
1477         int bytes_read;
1478
1479         ecryptfs_set_default_sizes(crypt_stat);
1480         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1481                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1482         offset = ECRYPTFS_FILE_SIZE_BYTES;
1483         rc = contains_ecryptfs_marker(page_virt + offset);
1484         if (rc == 0) {
1485                 rc = -EINVAL;
1486                 goto out;
1487         }
1488         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1489         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1490                                     &bytes_read);
1491         if (rc) {
1492                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1493                 goto out;
1494         }
1495         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1496                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1497                                 "file version [%d] is supported by this "
1498                                 "version of eCryptfs\n",
1499                                 crypt_stat->file_version,
1500                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1501                 rc = -EINVAL;
1502                 goto out;
1503         }
1504         offset += bytes_read;
1505         if (crypt_stat->file_version >= 1) {
1506                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1507                                            &bytes_read, validate_header_size);
1508                 if (rc) {
1509                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1510                                         "metadata; rc = [%d]\n", rc);
1511                 }
1512                 offset += bytes_read;
1513         } else
1514                 set_default_header_data(crypt_stat);
1515         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1516                                        ecryptfs_dentry);
1517 out:
1518         return rc;
1519 }
1520
1521 /**
1522  * ecryptfs_read_xattr_region
1523  * @page_virt: The vitual address into which to read the xattr data
1524  * @ecryptfs_inode: The eCryptfs inode
1525  *
1526  * Attempts to read the crypto metadata from the extended attribute
1527  * region of the lower file.
1528  *
1529  * Returns zero on success; non-zero on error
1530  */
1531 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1532 {
1533         struct dentry *lower_dentry =
1534                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1535         ssize_t size;
1536         int rc = 0;
1537
1538         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1539                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1540         if (size < 0) {
1541                 if (unlikely(ecryptfs_verbosity > 0))
1542                         printk(KERN_INFO "Error attempting to read the [%s] "
1543                                "xattr from the lower file; return value = "
1544                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1545                 rc = -EINVAL;
1546                 goto out;
1547         }
1548 out:
1549         return rc;
1550 }
1551
1552 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1553                                             struct dentry *ecryptfs_dentry)
1554 {
1555         int rc;
1556
1557         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
1558         if (rc)
1559                 goto out;
1560         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1561                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1562                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1563                 rc = -EINVAL;
1564         }
1565 out:
1566         return rc;
1567 }
1568
1569 /**
1570  * ecryptfs_read_metadata
1571  *
1572  * Common entry point for reading file metadata. From here, we could
1573  * retrieve the header information from the header region of the file,
1574  * the xattr region of the file, or some other repostory that is
1575  * stored separately from the file itself. The current implementation
1576  * supports retrieving the metadata information from the file contents
1577  * and from the xattr region.
1578  *
1579  * Returns zero if valid headers found and parsed; non-zero otherwise
1580  */
1581 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1582 {
1583         int rc = 0;
1584         char *page_virt = NULL;
1585         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1586         struct ecryptfs_crypt_stat *crypt_stat =
1587             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1588         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1589                 &ecryptfs_superblock_to_private(
1590                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1591
1592         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1593                                                       mount_crypt_stat);
1594         /* Read the first page from the underlying file */
1595         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1596         if (!page_virt) {
1597                 rc = -ENOMEM;
1598                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1599                        __func__);
1600                 goto out;
1601         }
1602         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1603                                  ecryptfs_inode);
1604         if (rc >= 0)
1605                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1606                                                 ecryptfs_dentry,
1607                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1608         if (rc) {
1609                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1610                 if (rc) {
1611                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1612                                "file header region or xattr region\n");
1613                         rc = -EINVAL;
1614                         goto out;
1615                 }
1616                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1617                                                 ecryptfs_dentry,
1618                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1619                 if (rc) {
1620                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1621                                "file xattr region either\n");
1622                         rc = -EINVAL;
1623                 }
1624                 if (crypt_stat->mount_crypt_stat->flags
1625                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1626                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1627                 } else {
1628                         printk(KERN_WARNING "Attempt to access file with "
1629                                "crypto metadata only in the extended attribute "
1630                                "region, but eCryptfs was mounted without "
1631                                "xattr support enabled. eCryptfs will not treat "
1632                                "this like an encrypted file.\n");
1633                         rc = -EINVAL;
1634                 }
1635         }
1636 out:
1637         if (page_virt) {
1638                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1639                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1640         }
1641         return rc;
1642 }
1643
1644 /**
1645  * ecryptfs_encrypt_filename - encrypt filename
1646  *
1647  * CBC-encrypts the filename. We do not want to encrypt the same
1648  * filename with the same key and IV, which may happen with hard
1649  * links, so we prepend random bits to each filename.
1650  *
1651  * Returns zero on success; non-zero otherwise
1652  */
1653 static int
1654 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1655                           struct ecryptfs_crypt_stat *crypt_stat,
1656                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1657 {
1658         int rc = 0;
1659
1660         filename->encrypted_filename = NULL;
1661         filename->encrypted_filename_size = 0;
1662         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1663             || (mount_crypt_stat && (mount_crypt_stat->flags
1664                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1665                 size_t packet_size;
1666                 size_t remaining_bytes;
1667
1668                 rc = ecryptfs_write_tag_70_packet(
1669                         NULL, NULL,
1670                         &filename->encrypted_filename_size,
1671                         mount_crypt_stat, NULL,
1672                         filename->filename_size);
1673                 if (rc) {
1674                         printk(KERN_ERR "%s: Error attempting to get packet "
1675                                "size for tag 72; rc = [%d]\n", __func__,
1676                                rc);
1677                         filename->encrypted_filename_size = 0;
1678                         goto out;
1679                 }
1680                 filename->encrypted_filename =
1681                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1682                 if (!filename->encrypted_filename) {
1683                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1684                                "to kmalloc [%zd] bytes\n", __func__,
1685                                filename->encrypted_filename_size);
1686                         rc = -ENOMEM;
1687                         goto out;
1688                 }
1689                 remaining_bytes = filename->encrypted_filename_size;
1690                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1691                                                   &remaining_bytes,
1692                                                   &packet_size,
1693                                                   mount_crypt_stat,
1694                                                   filename->filename,
1695                                                   filename->filename_size);
1696                 if (rc) {
1697                         printk(KERN_ERR "%s: Error attempting to generate "
1698                                "tag 70 packet; rc = [%d]\n", __func__,
1699                                rc);
1700                         kfree(filename->encrypted_filename);
1701                         filename->encrypted_filename = NULL;
1702                         filename->encrypted_filename_size = 0;
1703                         goto out;
1704                 }
1705                 filename->encrypted_filename_size = packet_size;
1706         } else {
1707                 printk(KERN_ERR "%s: No support for requested filename "
1708                        "encryption method in this release\n", __func__);
1709                 rc = -EOPNOTSUPP;
1710                 goto out;
1711         }
1712 out:
1713         return rc;
1714 }
1715
1716 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1717                                   const char *name, size_t name_size)
1718 {
1719         int rc = 0;
1720
1721         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1722         if (!(*copied_name)) {
1723                 rc = -ENOMEM;
1724                 goto out;
1725         }
1726         memcpy((void *)(*copied_name), (void *)name, name_size);
1727         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1728                                                  * in printing out the
1729                                                  * string in debug
1730                                                  * messages */
1731         (*copied_name_size) = name_size;
1732 out:
1733         return rc;
1734 }
1735
1736 /**
1737  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1738  * @key_tfm: Crypto context for key material, set by this function
1739  * @cipher_name: Name of the cipher
1740  * @key_size: Size of the key in bytes
1741  *
1742  * Returns zero on success. Any crypto_tfm structs allocated here
1743  * should be released by other functions, such as on a superblock put
1744  * event, regardless of whether this function succeeds for fails.
1745  */
1746 static int
1747 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1748                             char *cipher_name, size_t *key_size)
1749 {
1750         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1751         char *full_alg_name = NULL;
1752         int rc;
1753
1754         *key_tfm = NULL;
1755         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1756                 rc = -EINVAL;
1757                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1758                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1759                 goto out;
1760         }
1761         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1762                                                     "ecb");
1763         if (rc)
1764                 goto out;
1765         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1766         if (IS_ERR(*key_tfm)) {
1767                 rc = PTR_ERR(*key_tfm);
1768                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1769                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1770                 goto out;
1771         }
1772         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1773         if (*key_size == 0) {
1774                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1775
1776                 *key_size = alg->max_keysize;
1777         }
1778         get_random_bytes(dummy_key, *key_size);
1779         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1780         if (rc) {
1781                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1782                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1783                        rc);
1784                 rc = -EINVAL;
1785                 goto out;
1786         }
1787 out:
1788         kfree(full_alg_name);
1789         return rc;
1790 }
1791
1792 struct kmem_cache *ecryptfs_key_tfm_cache;
1793 static struct list_head key_tfm_list;
1794 struct mutex key_tfm_list_mutex;
1795
1796 int ecryptfs_init_crypto(void)
1797 {
1798         mutex_init(&key_tfm_list_mutex);
1799         INIT_LIST_HEAD(&key_tfm_list);
1800         return 0;
1801 }
1802
1803 /**
1804  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1805  *
1806  * Called only at module unload time
1807  */
1808 int ecryptfs_destroy_crypto(void)
1809 {
1810         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1811
1812         mutex_lock(&key_tfm_list_mutex);
1813         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1814                                  key_tfm_list) {
1815                 list_del(&key_tfm->key_tfm_list);
1816                 if (key_tfm->key_tfm)
1817                         crypto_free_blkcipher(key_tfm->key_tfm);
1818                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1819         }
1820         mutex_unlock(&key_tfm_list_mutex);
1821         return 0;
1822 }
1823
1824 int
1825 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1826                          size_t key_size)
1827 {
1828         struct ecryptfs_key_tfm *tmp_tfm;
1829         int rc = 0;
1830
1831         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1832
1833         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1834         if (key_tfm != NULL)
1835                 (*key_tfm) = tmp_tfm;
1836         if (!tmp_tfm) {
1837                 rc = -ENOMEM;
1838                 printk(KERN_ERR "Error attempting to allocate from "
1839                        "ecryptfs_key_tfm_cache\n");
1840                 goto out;
1841         }
1842         mutex_init(&tmp_tfm->key_tfm_mutex);
1843         strncpy(tmp_tfm->cipher_name, cipher_name,
1844                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1845         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1846         tmp_tfm->key_size = key_size;
1847         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1848                                          tmp_tfm->cipher_name,
1849                                          &tmp_tfm->key_size);
1850         if (rc) {
1851                 printk(KERN_ERR "Error attempting to initialize key TFM "
1852                        "cipher with name = [%s]; rc = [%d]\n",
1853                        tmp_tfm->cipher_name, rc);
1854                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1855                 if (key_tfm != NULL)
1856                         (*key_tfm) = NULL;
1857                 goto out;
1858         }
1859         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1860 out:
1861         return rc;
1862 }
1863
1864 /**
1865  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1866  * @cipher_name: the name of the cipher to search for
1867  * @key_tfm: set to corresponding tfm if found
1868  *
1869  * Searches for cached key_tfm matching @cipher_name
1870  * Must be called with &key_tfm_list_mutex held
1871  * Returns 1 if found, with @key_tfm set
1872  * Returns 0 if not found, with @key_tfm set to NULL
1873  */
1874 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1875 {
1876         struct ecryptfs_key_tfm *tmp_key_tfm;
1877
1878         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1879
1880         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1881                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1882                         if (key_tfm)
1883                                 (*key_tfm) = tmp_key_tfm;
1884                         return 1;
1885                 }
1886         }
1887         if (key_tfm)
1888                 (*key_tfm) = NULL;
1889         return 0;
1890 }
1891
1892 /**
1893  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1894  *
1895  * @tfm: set to cached tfm found, or new tfm created
1896  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1897  * @cipher_name: the name of the cipher to search for and/or add
1898  *
1899  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1900  * Searches for cached item first, and creates new if not found.
1901  * Returns 0 on success, non-zero if adding new cipher failed
1902  */
1903 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1904                                                struct mutex **tfm_mutex,
1905                                                char *cipher_name)
1906 {
1907         struct ecryptfs_key_tfm *key_tfm;
1908         int rc = 0;
1909
1910         (*tfm) = NULL;
1911         (*tfm_mutex) = NULL;
1912
1913         mutex_lock(&key_tfm_list_mutex);
1914         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1915                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1916                 if (rc) {
1917                         printk(KERN_ERR "Error adding new key_tfm to list; "
1918                                         "rc = [%d]\n", rc);
1919                         goto out;
1920                 }
1921         }
1922         (*tfm) = key_tfm->key_tfm;
1923         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1924 out:
1925         mutex_unlock(&key_tfm_list_mutex);
1926         return rc;
1927 }
1928
1929 /* 64 characters forming a 6-bit target field */
1930 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1931                                                  "EFGHIJKLMNOPQRST"
1932                                                  "UVWXYZabcdefghij"
1933                                                  "klmnopqrstuvwxyz");
1934
1935 /* We could either offset on every reverse map or just pad some 0x00's
1936  * at the front here */
1937 static const unsigned char filename_rev_map[] = {
1938         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1939         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1940         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1941         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1942         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1943         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1944         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1945         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1946         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1947         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1948         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1949         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1950         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1951         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1952         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1953         0x3D, 0x3E, 0x3F
1954 };
1955
1956 /**
1957  * ecryptfs_encode_for_filename
1958  * @dst: Destination location for encoded filename
1959  * @dst_size: Size of the encoded filename in bytes
1960  * @src: Source location for the filename to encode
1961  * @src_size: Size of the source in bytes
1962  */
1963 void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1964                                   unsigned char *src, size_t src_size)
1965 {
1966         size_t num_blocks;
1967         size_t block_num = 0;
1968         size_t dst_offset = 0;
1969         unsigned char last_block[3];
1970
1971         if (src_size == 0) {
1972                 (*dst_size) = 0;
1973                 goto out;
1974         }
1975         num_blocks = (src_size / 3);
1976         if ((src_size % 3) == 0) {
1977                 memcpy(last_block, (&src[src_size - 3]), 3);
1978         } else {
1979                 num_blocks++;
1980                 last_block[2] = 0x00;
1981                 switch (src_size % 3) {
1982                 case 1:
1983                         last_block[0] = src[src_size - 1];
1984                         last_block[1] = 0x00;
1985                         break;
1986                 case 2:
1987                         last_block[0] = src[src_size - 2];
1988                         last_block[1] = src[src_size - 1];
1989                 }
1990         }
1991         (*dst_size) = (num_blocks * 4);
1992         if (!dst)
1993                 goto out;
1994         while (block_num < num_blocks) {
1995                 unsigned char *src_block;
1996                 unsigned char dst_block[4];
1997
1998                 if (block_num == (num_blocks - 1))
1999                         src_block = last_block;
2000                 else
2001                         src_block = &src[block_num * 3];
2002                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
2003                 dst_block[1] = (((src_block[0] << 4) & 0x30)
2004                                 | ((src_block[1] >> 4) & 0x0F));
2005                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
2006                                 | ((src_block[2] >> 6) & 0x03));
2007                 dst_block[3] = (src_block[2] & 0x3F);
2008                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
2009                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
2010                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
2011                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
2012                 block_num++;
2013         }
2014 out:
2015         return;
2016 }
2017
2018 /**
2019  * ecryptfs_decode_from_filename
2020  * @dst: If NULL, this function only sets @dst_size and returns. If
2021  *       non-NULL, this function decodes the encoded octets in @src
2022  *       into the memory that @dst points to.
2023  * @dst_size: Set to the size of the decoded string.
2024  * @src: The encoded set of octets to decode.
2025  * @src_size: The size of the encoded set of octets to decode.
2026  */
2027 static void
2028 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2029                               const unsigned char *src, size_t src_size)
2030 {
2031         u8 current_bit_offset = 0;
2032         size_t src_byte_offset = 0;
2033         size_t dst_byte_offset = 0;
2034
2035         if (dst == NULL) {
2036                 /* Not exact; conservatively long. Every block of 4
2037                  * encoded characters decodes into a block of 3
2038                  * decoded characters. This segment of code provides
2039                  * the caller with the maximum amount of allocated
2040                  * space that @dst will need to point to in a
2041                  * subsequent call. */
2042                 (*dst_size) = (((src_size + 1) * 3) / 4);
2043                 goto out;
2044         }
2045         while (src_byte_offset < src_size) {
2046                 unsigned char src_byte =
2047                                 filename_rev_map[(int)src[src_byte_offset]];
2048
2049                 switch (current_bit_offset) {
2050                 case 0:
2051                         dst[dst_byte_offset] = (src_byte << 2);
2052                         current_bit_offset = 6;
2053                         break;
2054                 case 6:
2055                         dst[dst_byte_offset++] |= (src_byte >> 4);
2056                         dst[dst_byte_offset] = ((src_byte & 0xF)
2057                                                  << 4);
2058                         current_bit_offset = 4;
2059                         break;
2060                 case 4:
2061                         dst[dst_byte_offset++] |= (src_byte >> 2);
2062                         dst[dst_byte_offset] = (src_byte << 6);
2063                         current_bit_offset = 2;
2064                         break;
2065                 case 2:
2066                         dst[dst_byte_offset++] |= (src_byte);
2067                         dst[dst_byte_offset] = 0;
2068                         current_bit_offset = 0;
2069                         break;
2070                 }
2071                 src_byte_offset++;
2072         }
2073         (*dst_size) = dst_byte_offset;
2074 out:
2075         return;
2076 }
2077
2078 /**
2079  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2080  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2081  * @name: The plaintext name
2082  * @length: The length of the plaintext
2083  * @encoded_name: The encypted name
2084  *
2085  * Encrypts and encodes a filename into something that constitutes a
2086  * valid filename for a filesystem, with printable characters.
2087  *
2088  * We assume that we have a properly initialized crypto context,
2089  * pointed to by crypt_stat->tfm.
2090  *
2091  * Returns zero on success; non-zero on otherwise
2092  */
2093 int ecryptfs_encrypt_and_encode_filename(
2094         char **encoded_name,
2095         size_t *encoded_name_size,
2096         struct ecryptfs_crypt_stat *crypt_stat,
2097         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2098         const char *name, size_t name_size)
2099 {
2100         size_t encoded_name_no_prefix_size;
2101         int rc = 0;
2102
2103         (*encoded_name) = NULL;
2104         (*encoded_name_size) = 0;
2105         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2106             || (mount_crypt_stat && (mount_crypt_stat->flags
2107                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2108                 struct ecryptfs_filename *filename;
2109
2110                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2111                 if (!filename) {
2112                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2113                                "to kzalloc [%zd] bytes\n", __func__,
2114                                sizeof(*filename));
2115                         rc = -ENOMEM;
2116                         goto out;
2117                 }
2118                 filename->filename = (char *)name;
2119                 filename->filename_size = name_size;
2120                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2121                                                mount_crypt_stat);
2122                 if (rc) {
2123                         printk(KERN_ERR "%s: Error attempting to encrypt "
2124                                "filename; rc = [%d]\n", __func__, rc);
2125                         kfree(filename);
2126                         goto out;
2127                 }
2128                 ecryptfs_encode_for_filename(
2129                         NULL, &encoded_name_no_prefix_size,
2130                         filename->encrypted_filename,
2131                         filename->encrypted_filename_size);
2132                 if ((crypt_stat && (crypt_stat->flags
2133                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2134                     || (mount_crypt_stat
2135                         && (mount_crypt_stat->flags
2136                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2137                         (*encoded_name_size) =
2138                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2139                                  + encoded_name_no_prefix_size);
2140                 else
2141                         (*encoded_name_size) =
2142                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2143                                  + encoded_name_no_prefix_size);
2144                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2145                 if (!(*encoded_name)) {
2146                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2147                                "to kzalloc [%zd] bytes\n", __func__,
2148                                (*encoded_name_size));
2149                         rc = -ENOMEM;
2150                         kfree(filename->encrypted_filename);
2151                         kfree(filename);
2152                         goto out;
2153                 }
2154                 if ((crypt_stat && (crypt_stat->flags
2155                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2156                     || (mount_crypt_stat
2157                         && (mount_crypt_stat->flags
2158                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2159                         memcpy((*encoded_name),
2160                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2161                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2162                         ecryptfs_encode_for_filename(
2163                             ((*encoded_name)
2164                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2165                             &encoded_name_no_prefix_size,
2166                             filename->encrypted_filename,
2167                             filename->encrypted_filename_size);
2168                         (*encoded_name_size) =
2169                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2170                                  + encoded_name_no_prefix_size);
2171                         (*encoded_name)[(*encoded_name_size)] = '\0';
2172                         (*encoded_name_size)++;
2173                 } else {
2174                         rc = -EOPNOTSUPP;
2175                 }
2176                 if (rc) {
2177                         printk(KERN_ERR "%s: Error attempting to encode "
2178                                "encrypted filename; rc = [%d]\n", __func__,
2179                                rc);
2180                         kfree((*encoded_name));
2181                         (*encoded_name) = NULL;
2182                         (*encoded_name_size) = 0;
2183                 }
2184                 kfree(filename->encrypted_filename);
2185                 kfree(filename);
2186         } else {
2187                 rc = ecryptfs_copy_filename(encoded_name,
2188                                             encoded_name_size,
2189                                             name, name_size);
2190         }
2191 out:
2192         return rc;
2193 }
2194
2195 /**
2196  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2197  * @plaintext_name: The plaintext name
2198  * @plaintext_name_size: The plaintext name size
2199  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2200  * @name: The filename in cipher text
2201  * @name_size: The cipher text name size
2202  *
2203  * Decrypts and decodes the filename.
2204  *
2205  * Returns zero on error; non-zero otherwise
2206  */
2207 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2208                                          size_t *plaintext_name_size,
2209                                          struct dentry *ecryptfs_dir_dentry,
2210                                          const char *name, size_t name_size)
2211 {
2212         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2213                 &ecryptfs_superblock_to_private(
2214                         ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2215         char *decoded_name;
2216         size_t decoded_name_size;
2217         size_t packet_size;
2218         int rc = 0;
2219
2220         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2221             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2222             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2223             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2224                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2225                 const char *orig_name = name;
2226                 size_t orig_name_size = name_size;
2227
2228                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2229                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2230                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2231                                               name, name_size);
2232                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2233                 if (!decoded_name) {
2234                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2235                                "to kmalloc [%zd] bytes\n", __func__,
2236                                decoded_name_size);
2237                         rc = -ENOMEM;
2238                         goto out;
2239                 }
2240                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2241                                               name, name_size);
2242                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2243                                                   plaintext_name_size,
2244                                                   &packet_size,
2245                                                   mount_crypt_stat,
2246                                                   decoded_name,
2247                                                   decoded_name_size);
2248                 if (rc) {
2249                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2250                                "from filename; copying through filename "
2251                                "as-is\n", __func__);
2252                         rc = ecryptfs_copy_filename(plaintext_name,
2253                                                     plaintext_name_size,
2254                                                     orig_name, orig_name_size);
2255                         goto out_free;
2256                 }
2257         } else {
2258                 rc = ecryptfs_copy_filename(plaintext_name,
2259                                             plaintext_name_size,
2260                                             name, name_size);
2261                 goto out;
2262         }
2263 out_free:
2264         kfree(decoded_name);
2265 out:
2266         return rc;
2267 }