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TOMOYO Linux Cross Reference
Linux/fs/ecryptfs/crypto.c

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  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 <crypto/hash.h>
 27 #include <crypto/skcipher.h>
 28 #include <linux/fs.h>
 29 #include <linux/mount.h>
 30 #include <linux/pagemap.h>
 31 #include <linux/random.h>
 32 #include <linux/compiler.h>
 33 #include <linux/key.h>
 34 #include <linux/namei.h>
 35 #include <linux/file.h>
 36 #include <linux/scatterlist.h>
 37 #include <linux/slab.h>
 38 #include <asm/unaligned.h>
 39 #include "ecryptfs_kernel.h"
 40 
 41 #define DECRYPT         0
 42 #define ENCRYPT         1
 43 
 44 /**
 45  * ecryptfs_to_hex
 46  * @dst: Buffer to take hex character representation of contents of
 47  *       src; must be at least of size (src_size * 2)
 48  * @src: Buffer to be converted to a hex string respresentation
 49  * @src_size: number of bytes to convert
 50  */
 51 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
 52 {
 53         int x;
 54 
 55         for (x = 0; x < src_size; x++)
 56                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
 57 }
 58 
 59 /**
 60  * ecryptfs_from_hex
 61  * @dst: Buffer to take the bytes from src hex; must be at least of
 62  *       size (src_size / 2)
 63  * @src: Buffer to be converted from a hex string respresentation to raw value
 64  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
 65  */
 66 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
 67 {
 68         int x;
 69         char tmp[3] = { 0, };
 70 
 71         for (x = 0; x < dst_size; x++) {
 72                 tmp[0] = src[x * 2];
 73                 tmp[1] = src[x * 2 + 1];
 74                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
 75         }
 76 }
 77 
 78 static int ecryptfs_hash_digest(struct crypto_shash *tfm,
 79                                 char *src, int len, char *dst)
 80 {
 81         SHASH_DESC_ON_STACK(desc, tfm);
 82         int err;
 83 
 84         desc->tfm = tfm;
 85         desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 86         err = crypto_shash_digest(desc, src, len, dst);
 87         shash_desc_zero(desc);
 88         return err;
 89 }
 90 
 91 /**
 92  * ecryptfs_calculate_md5 - calculates the md5 of @src
 93  * @dst: Pointer to 16 bytes of allocated memory
 94  * @crypt_stat: Pointer to crypt_stat struct for the current inode
 95  * @src: Data to be md5'd
 96  * @len: Length of @src
 97  *
 98  * Uses the allocated crypto context that crypt_stat references to
 99  * generate the MD5 sum of the contents of src.
100  */
101 static int ecryptfs_calculate_md5(char *dst,
102                                   struct ecryptfs_crypt_stat *crypt_stat,
103                                   char *src, int len)
104 {
105         struct crypto_shash *tfm;
106         int rc = 0;
107 
108         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
109         tfm = crypt_stat->hash_tfm;
110         if (!tfm) {
111                 tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
112                 if (IS_ERR(tfm)) {
113                         rc = PTR_ERR(tfm);
114                         ecryptfs_printk(KERN_ERR, "Error attempting to "
115                                         "allocate crypto context; rc = [%d]\n",
116                                         rc);
117                         goto out;
118                 }
119                 crypt_stat->hash_tfm = tfm;
120         }
121         rc = ecryptfs_hash_digest(tfm, src, len, dst);
122         if (rc) {
123                 printk(KERN_ERR
124                        "%s: Error computing crypto hash; rc = [%d]\n",
125                        __func__, rc);
126                 goto out;
127         }
128 out:
129         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
130         return rc;
131 }
132 
133 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
134                                                   char *cipher_name,
135                                                   char *chaining_modifier)
136 {
137         int cipher_name_len = strlen(cipher_name);
138         int chaining_modifier_len = strlen(chaining_modifier);
139         int algified_name_len;
140         int rc;
141 
142         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
143         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
144         if (!(*algified_name)) {
145                 rc = -ENOMEM;
146                 goto out;
147         }
148         snprintf((*algified_name), algified_name_len, "%s(%s)",
149                  chaining_modifier, cipher_name);
150         rc = 0;
151 out:
152         return rc;
153 }
154 
155 /**
156  * ecryptfs_derive_iv
157  * @iv: destination for the derived iv vale
158  * @crypt_stat: Pointer to crypt_stat struct for the current inode
159  * @offset: Offset of the extent whose IV we are to derive
160  *
161  * Generate the initialization vector from the given root IV and page
162  * offset.
163  *
164  * Returns zero on success; non-zero on error.
165  */
166 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
167                        loff_t offset)
168 {
169         int rc = 0;
170         char dst[MD5_DIGEST_SIZE];
171         char src[ECRYPTFS_MAX_IV_BYTES + 16];
172 
173         if (unlikely(ecryptfs_verbosity > 0)) {
174                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
175                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
176         }
177         /* TODO: It is probably secure to just cast the least
178          * significant bits of the root IV into an unsigned long and
179          * add the offset to that rather than go through all this
180          * hashing business. -Halcrow */
181         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
182         memset((src + crypt_stat->iv_bytes), 0, 16);
183         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
184         if (unlikely(ecryptfs_verbosity > 0)) {
185                 ecryptfs_printk(KERN_DEBUG, "source:\n");
186                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
187         }
188         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
189                                     (crypt_stat->iv_bytes + 16));
190         if (rc) {
191                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
192                                 "MD5 while generating IV for a page\n");
193                 goto out;
194         }
195         memcpy(iv, dst, crypt_stat->iv_bytes);
196         if (unlikely(ecryptfs_verbosity > 0)) {
197                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
198                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
199         }
200 out:
201         return rc;
202 }
203 
204 /**
205  * ecryptfs_init_crypt_stat
206  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
207  *
208  * Initialize the crypt_stat structure.
209  */
210 void
211 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
212 {
213         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
214         INIT_LIST_HEAD(&crypt_stat->keysig_list);
215         mutex_init(&crypt_stat->keysig_list_mutex);
216         mutex_init(&crypt_stat->cs_mutex);
217         mutex_init(&crypt_stat->cs_tfm_mutex);
218         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
219         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
220 }
221 
222 /**
223  * ecryptfs_destroy_crypt_stat
224  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
225  *
226  * Releases all memory associated with a crypt_stat struct.
227  */
228 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
229 {
230         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
231 
232         crypto_free_skcipher(crypt_stat->tfm);
233         crypto_free_shash(crypt_stat->hash_tfm);
234         list_for_each_entry_safe(key_sig, key_sig_tmp,
235                                  &crypt_stat->keysig_list, crypt_stat_list) {
236                 list_del(&key_sig->crypt_stat_list);
237                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
238         }
239         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
240 }
241 
242 void ecryptfs_destroy_mount_crypt_stat(
243         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
244 {
245         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
246 
247         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
248                 return;
249         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
250         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
251                                  &mount_crypt_stat->global_auth_tok_list,
252                                  mount_crypt_stat_list) {
253                 list_del(&auth_tok->mount_crypt_stat_list);
254                 if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
255                         key_put(auth_tok->global_auth_tok_key);
256                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
257         }
258         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
259         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
260 }
261 
262 /**
263  * virt_to_scatterlist
264  * @addr: Virtual address
265  * @size: Size of data; should be an even multiple of the block size
266  * @sg: Pointer to scatterlist array; set to NULL to obtain only
267  *      the number of scatterlist structs required in array
268  * @sg_size: Max array size
269  *
270  * Fills in a scatterlist array with page references for a passed
271  * virtual address.
272  *
273  * Returns the number of scatterlist structs in array used
274  */
275 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
276                         int sg_size)
277 {
278         int i = 0;
279         struct page *pg;
280         int offset;
281         int remainder_of_page;
282 
283         sg_init_table(sg, sg_size);
284 
285         while (size > 0 && i < sg_size) {
286                 pg = virt_to_page(addr);
287                 offset = offset_in_page(addr);
288                 sg_set_page(&sg[i], pg, 0, offset);
289                 remainder_of_page = PAGE_SIZE - offset;
290                 if (size >= remainder_of_page) {
291                         sg[i].length = remainder_of_page;
292                         addr += remainder_of_page;
293                         size -= remainder_of_page;
294                 } else {
295                         sg[i].length = size;
296                         addr += size;
297                         size = 0;
298                 }
299                 i++;
300         }
301         if (size > 0)
302                 return -ENOMEM;
303         return i;
304 }
305 
306 struct extent_crypt_result {
307         struct completion completion;
308         int rc;
309 };
310 
311 static void extent_crypt_complete(struct crypto_async_request *req, int rc)
312 {
313         struct extent_crypt_result *ecr = req->data;
314 
315         if (rc == -EINPROGRESS)
316                 return;
317 
318         ecr->rc = rc;
319         complete(&ecr->completion);
320 }
321 
322 /**
323  * crypt_scatterlist
324  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
325  * @dst_sg: Destination of the data after performing the crypto operation
326  * @src_sg: Data to be encrypted or decrypted
327  * @size: Length of data
328  * @iv: IV to use
329  * @op: ENCRYPT or DECRYPT to indicate the desired operation
330  *
331  * Returns the number of bytes encrypted or decrypted; negative value on error
332  */
333 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
334                              struct scatterlist *dst_sg,
335                              struct scatterlist *src_sg, int size,
336                              unsigned char *iv, int op)
337 {
338         struct skcipher_request *req = NULL;
339         struct extent_crypt_result ecr;
340         int rc = 0;
341 
342         BUG_ON(!crypt_stat || !crypt_stat->tfm
343                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
344         if (unlikely(ecryptfs_verbosity > 0)) {
345                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
346                                 crypt_stat->key_size);
347                 ecryptfs_dump_hex(crypt_stat->key,
348                                   crypt_stat->key_size);
349         }
350 
351         init_completion(&ecr.completion);
352 
353         mutex_lock(&crypt_stat->cs_tfm_mutex);
354         req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
355         if (!req) {
356                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
357                 rc = -ENOMEM;
358                 goto out;
359         }
360 
361         skcipher_request_set_callback(req,
362                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
363                         extent_crypt_complete, &ecr);
364         /* Consider doing this once, when the file is opened */
365         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
366                 rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
367                                             crypt_stat->key_size);
368                 if (rc) {
369                         ecryptfs_printk(KERN_ERR,
370                                         "Error setting key; rc = [%d]\n",
371                                         rc);
372                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
373                         rc = -EINVAL;
374                         goto out;
375                 }
376                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
377         }
378         mutex_unlock(&crypt_stat->cs_tfm_mutex);
379         skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
380         rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
381                              crypto_skcipher_decrypt(req);
382         if (rc == -EINPROGRESS || rc == -EBUSY) {
383                 struct extent_crypt_result *ecr = req->base.data;
384 
385                 wait_for_completion(&ecr->completion);
386                 rc = ecr->rc;
387                 reinit_completion(&ecr->completion);
388         }
389 out:
390         skcipher_request_free(req);
391         return rc;
392 }
393 
394 /**
395  * lower_offset_for_page
396  *
397  * Convert an eCryptfs page index into a lower byte offset
398  */
399 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
400                                     struct page *page)
401 {
402         return ecryptfs_lower_header_size(crypt_stat) +
403                ((loff_t)page->index << PAGE_SHIFT);
404 }
405 
406 /**
407  * crypt_extent
408  * @crypt_stat: crypt_stat containing cryptographic context for the
409  *              encryption operation
410  * @dst_page: The page to write the result into
411  * @src_page: The page to read from
412  * @extent_offset: Page extent offset for use in generating IV
413  * @op: ENCRYPT or DECRYPT to indicate the desired operation
414  *
415  * Encrypts or decrypts one extent of data.
416  *
417  * Return zero on success; non-zero otherwise
418  */
419 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
420                         struct page *dst_page,
421                         struct page *src_page,
422                         unsigned long extent_offset, int op)
423 {
424         pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
425         loff_t extent_base;
426         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
427         struct scatterlist src_sg, dst_sg;
428         size_t extent_size = crypt_stat->extent_size;
429         int rc;
430 
431         extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
432         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
433                                 (extent_base + extent_offset));
434         if (rc) {
435                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
436                         "extent [0x%.16llx]; rc = [%d]\n",
437                         (unsigned long long)(extent_base + extent_offset), rc);
438                 goto out;
439         }
440 
441         sg_init_table(&src_sg, 1);
442         sg_init_table(&dst_sg, 1);
443 
444         sg_set_page(&src_sg, src_page, extent_size,
445                     extent_offset * extent_size);
446         sg_set_page(&dst_sg, dst_page, extent_size,
447                     extent_offset * extent_size);
448 
449         rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
450                                extent_iv, op);
451         if (rc < 0) {
452                 printk(KERN_ERR "%s: Error attempting to crypt page with "
453                        "page_index = [%ld], extent_offset = [%ld]; "
454                        "rc = [%d]\n", __func__, page_index, extent_offset, rc);
455                 goto out;
456         }
457         rc = 0;
458 out:
459         return rc;
460 }
461 
462 /**
463  * ecryptfs_encrypt_page
464  * @page: Page mapped from the eCryptfs inode for the file; contains
465  *        decrypted content that needs to be encrypted (to a temporary
466  *        page; not in place) and written out to the lower file
467  *
468  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
469  * that eCryptfs pages may straddle the lower pages -- for instance,
470  * if the file was created on a machine with an 8K page size
471  * (resulting in an 8K header), and then the file is copied onto a
472  * host with a 32K page size, then when reading page 0 of the eCryptfs
473  * file, 24K of page 0 of the lower file will be read and decrypted,
474  * and then 8K of page 1 of the lower file will be read and decrypted.
475  *
476  * Returns zero on success; negative on error
477  */
478 int ecryptfs_encrypt_page(struct page *page)
479 {
480         struct inode *ecryptfs_inode;
481         struct ecryptfs_crypt_stat *crypt_stat;
482         char *enc_extent_virt;
483         struct page *enc_extent_page = NULL;
484         loff_t extent_offset;
485         loff_t lower_offset;
486         int rc = 0;
487 
488         ecryptfs_inode = page->mapping->host;
489         crypt_stat =
490                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
491         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
492         enc_extent_page = alloc_page(GFP_USER);
493         if (!enc_extent_page) {
494                 rc = -ENOMEM;
495                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
496                                 "encrypted extent\n");
497                 goto out;
498         }
499 
500         for (extent_offset = 0;
501              extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
502              extent_offset++) {
503                 rc = crypt_extent(crypt_stat, enc_extent_page, page,
504                                   extent_offset, ENCRYPT);
505                 if (rc) {
506                         printk(KERN_ERR "%s: Error encrypting extent; "
507                                "rc = [%d]\n", __func__, rc);
508                         goto out;
509                 }
510         }
511 
512         lower_offset = lower_offset_for_page(crypt_stat, page);
513         enc_extent_virt = kmap(enc_extent_page);
514         rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
515                                   PAGE_SIZE);
516         kunmap(enc_extent_page);
517         if (rc < 0) {
518                 ecryptfs_printk(KERN_ERR,
519                         "Error attempting to write lower page; rc = [%d]\n",
520                         rc);
521                 goto out;
522         }
523         rc = 0;
524 out:
525         if (enc_extent_page) {
526                 __free_page(enc_extent_page);
527         }
528         return rc;
529 }
530 
531 /**
532  * ecryptfs_decrypt_page
533  * @page: Page mapped from the eCryptfs inode for the file; data read
534  *        and decrypted from the lower file will be written into this
535  *        page
536  *
537  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
538  * that eCryptfs pages may straddle the lower pages -- for instance,
539  * if the file was created on a machine with an 8K page size
540  * (resulting in an 8K header), and then the file is copied onto a
541  * host with a 32K page size, then when reading page 0 of the eCryptfs
542  * file, 24K of page 0 of the lower file will be read and decrypted,
543  * and then 8K of page 1 of the lower file will be read and decrypted.
544  *
545  * Returns zero on success; negative on error
546  */
547 int ecryptfs_decrypt_page(struct page *page)
548 {
549         struct inode *ecryptfs_inode;
550         struct ecryptfs_crypt_stat *crypt_stat;
551         char *page_virt;
552         unsigned long extent_offset;
553         loff_t lower_offset;
554         int rc = 0;
555 
556         ecryptfs_inode = page->mapping->host;
557         crypt_stat =
558                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
559         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
560 
561         lower_offset = lower_offset_for_page(crypt_stat, page);
562         page_virt = kmap(page);
563         rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
564                                  ecryptfs_inode);
565         kunmap(page);
566         if (rc < 0) {
567                 ecryptfs_printk(KERN_ERR,
568                         "Error attempting to read lower page; rc = [%d]\n",
569                         rc);
570                 goto out;
571         }
572 
573         for (extent_offset = 0;
574              extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
575              extent_offset++) {
576                 rc = crypt_extent(crypt_stat, page, page,
577                                   extent_offset, DECRYPT);
578                 if (rc) {
579                         printk(KERN_ERR "%s: Error encrypting extent; "
580                                "rc = [%d]\n", __func__, rc);
581                         goto out;
582                 }
583         }
584 out:
585         return rc;
586 }
587 
588 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
589 
590 /**
591  * ecryptfs_init_crypt_ctx
592  * @crypt_stat: Uninitialized crypt stats structure
593  *
594  * Initialize the crypto context.
595  *
596  * TODO: Performance: Keep a cache of initialized cipher contexts;
597  * only init if needed
598  */
599 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
600 {
601         char *full_alg_name;
602         int rc = -EINVAL;
603 
604         ecryptfs_printk(KERN_DEBUG,
605                         "Initializing cipher [%s]; strlen = [%d]; "
606                         "key_size_bits = [%zd]\n",
607                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
608                         crypt_stat->key_size << 3);
609         mutex_lock(&crypt_stat->cs_tfm_mutex);
610         if (crypt_stat->tfm) {
611                 rc = 0;
612                 goto out_unlock;
613         }
614         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
615                                                     crypt_stat->cipher, "cbc");
616         if (rc)
617                 goto out_unlock;
618         crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
619         if (IS_ERR(crypt_stat->tfm)) {
620                 rc = PTR_ERR(crypt_stat->tfm);
621                 crypt_stat->tfm = NULL;
622                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
623                                 "Error initializing cipher [%s]\n",
624                                 full_alg_name);
625                 goto out_free;
626         }
627         crypto_skcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
628         rc = 0;
629 out_free:
630         kfree(full_alg_name);
631 out_unlock:
632         mutex_unlock(&crypt_stat->cs_tfm_mutex);
633         return rc;
634 }
635 
636 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
637 {
638         int extent_size_tmp;
639 
640         crypt_stat->extent_mask = 0xFFFFFFFF;
641         crypt_stat->extent_shift = 0;
642         if (crypt_stat->extent_size == 0)
643                 return;
644         extent_size_tmp = crypt_stat->extent_size;
645         while ((extent_size_tmp & 0x01) == 0) {
646                 extent_size_tmp >>= 1;
647                 crypt_stat->extent_mask <<= 1;
648                 crypt_stat->extent_shift++;
649         }
650 }
651 
652 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
653 {
654         /* Default values; may be overwritten as we are parsing the
655          * packets. */
656         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
657         set_extent_mask_and_shift(crypt_stat);
658         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
659         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
660                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
661         else {
662                 if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
663                         crypt_stat->metadata_size =
664                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
665                 else
666                         crypt_stat->metadata_size = PAGE_SIZE;
667         }
668 }
669 
670 /**
671  * ecryptfs_compute_root_iv
672  * @crypt_stats
673  *
674  * On error, sets the root IV to all 0's.
675  */
676 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
677 {
678         int rc = 0;
679         char dst[MD5_DIGEST_SIZE];
680 
681         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
682         BUG_ON(crypt_stat->iv_bytes <= 0);
683         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
684                 rc = -EINVAL;
685                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
686                                 "cannot generate root IV\n");
687                 goto out;
688         }
689         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
690                                     crypt_stat->key_size);
691         if (rc) {
692                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
693                                 "MD5 while generating root IV\n");
694                 goto out;
695         }
696         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
697 out:
698         if (rc) {
699                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
700                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
701         }
702         return rc;
703 }
704 
705 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
706 {
707         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
708         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
709         ecryptfs_compute_root_iv(crypt_stat);
710         if (unlikely(ecryptfs_verbosity > 0)) {
711                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
712                 ecryptfs_dump_hex(crypt_stat->key,
713                                   crypt_stat->key_size);
714         }
715 }
716 
717 /**
718  * ecryptfs_copy_mount_wide_flags_to_inode_flags
719  * @crypt_stat: The inode's cryptographic context
720  * @mount_crypt_stat: The mount point's cryptographic context
721  *
722  * This function propagates the mount-wide flags to individual inode
723  * flags.
724  */
725 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
726         struct ecryptfs_crypt_stat *crypt_stat,
727         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
728 {
729         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
730                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
731         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
732                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
733         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
734                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
735                 if (mount_crypt_stat->flags
736                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
737                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
738                 else if (mount_crypt_stat->flags
739                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
740                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
741         }
742 }
743 
744 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
745         struct ecryptfs_crypt_stat *crypt_stat,
746         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
747 {
748         struct ecryptfs_global_auth_tok *global_auth_tok;
749         int rc = 0;
750 
751         mutex_lock(&crypt_stat->keysig_list_mutex);
752         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
753 
754         list_for_each_entry(global_auth_tok,
755                             &mount_crypt_stat->global_auth_tok_list,
756                             mount_crypt_stat_list) {
757                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
758                         continue;
759                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
760                 if (rc) {
761                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
762                         goto out;
763                 }
764         }
765 
766 out:
767         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
768         mutex_unlock(&crypt_stat->keysig_list_mutex);
769         return rc;
770 }
771 
772 /**
773  * ecryptfs_set_default_crypt_stat_vals
774  * @crypt_stat: The inode's cryptographic context
775  * @mount_crypt_stat: The mount point's cryptographic context
776  *
777  * Default values in the event that policy does not override them.
778  */
779 static void ecryptfs_set_default_crypt_stat_vals(
780         struct ecryptfs_crypt_stat *crypt_stat,
781         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
782 {
783         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
784                                                       mount_crypt_stat);
785         ecryptfs_set_default_sizes(crypt_stat);
786         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
787         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
788         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
789         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
790         crypt_stat->mount_crypt_stat = mount_crypt_stat;
791 }
792 
793 /**
794  * ecryptfs_new_file_context
795  * @ecryptfs_inode: The eCryptfs inode
796  *
797  * If the crypto context for the file has not yet been established,
798  * this is where we do that.  Establishing a new crypto context
799  * involves the following decisions:
800  *  - What cipher to use?
801  *  - What set of authentication tokens to use?
802  * Here we just worry about getting enough information into the
803  * authentication tokens so that we know that they are available.
804  * We associate the available authentication tokens with the new file
805  * via the set of signatures in the crypt_stat struct.  Later, when
806  * the headers are actually written out, we may again defer to
807  * userspace to perform the encryption of the session key; for the
808  * foreseeable future, this will be the case with public key packets.
809  *
810  * Returns zero on success; non-zero otherwise
811  */
812 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
813 {
814         struct ecryptfs_crypt_stat *crypt_stat =
815             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
816         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
817             &ecryptfs_superblock_to_private(
818                     ecryptfs_inode->i_sb)->mount_crypt_stat;
819         int cipher_name_len;
820         int rc = 0;
821 
822         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
823         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
824         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
825                                                       mount_crypt_stat);
826         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
827                                                          mount_crypt_stat);
828         if (rc) {
829                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
830                        "to the inode key sigs; rc = [%d]\n", rc);
831                 goto out;
832         }
833         cipher_name_len =
834                 strlen(mount_crypt_stat->global_default_cipher_name);
835         memcpy(crypt_stat->cipher,
836                mount_crypt_stat->global_default_cipher_name,
837                cipher_name_len);
838         crypt_stat->cipher[cipher_name_len] = '\0';
839         crypt_stat->key_size =
840                 mount_crypt_stat->global_default_cipher_key_size;
841         ecryptfs_generate_new_key(crypt_stat);
842         rc = ecryptfs_init_crypt_ctx(crypt_stat);
843         if (rc)
844                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
845                                 "context for cipher [%s]: rc = [%d]\n",
846                                 crypt_stat->cipher, rc);
847 out:
848         return rc;
849 }
850 
851 /**
852  * ecryptfs_validate_marker - check for the ecryptfs marker
853  * @data: The data block in which to check
854  *
855  * Returns zero if marker found; -EINVAL if not found
856  */
857 static int ecryptfs_validate_marker(char *data)
858 {
859         u32 m_1, m_2;
860 
861         m_1 = get_unaligned_be32(data);
862         m_2 = get_unaligned_be32(data + 4);
863         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
864                 return 0;
865         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
866                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
867                         MAGIC_ECRYPTFS_MARKER);
868         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
869                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
870         return -EINVAL;
871 }
872 
873 struct ecryptfs_flag_map_elem {
874         u32 file_flag;
875         u32 local_flag;
876 };
877 
878 /* Add support for additional flags by adding elements here. */
879 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
880         {0x00000001, ECRYPTFS_ENABLE_HMAC},
881         {0x00000002, ECRYPTFS_ENCRYPTED},
882         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
883         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
884 };
885 
886 /**
887  * ecryptfs_process_flags
888  * @crypt_stat: The cryptographic context
889  * @page_virt: Source data to be parsed
890  * @bytes_read: Updated with the number of bytes read
891  *
892  * Returns zero on success; non-zero if the flag set is invalid
893  */
894 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
895                                   char *page_virt, int *bytes_read)
896 {
897         int rc = 0;
898         int i;
899         u32 flags;
900 
901         flags = get_unaligned_be32(page_virt);
902         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
903                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
904                 if (flags & ecryptfs_flag_map[i].file_flag) {
905                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
906                 } else
907                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
908         /* Version is in top 8 bits of the 32-bit flag vector */
909         crypt_stat->file_version = ((flags >> 24) & 0xFF);
910         (*bytes_read) = 4;
911         return rc;
912 }
913 
914 /**
915  * write_ecryptfs_marker
916  * @page_virt: The pointer to in a page to begin writing the marker
917  * @written: Number of bytes written
918  *
919  * Marker = 0x3c81b7f5
920  */
921 static void write_ecryptfs_marker(char *page_virt, size_t *written)
922 {
923         u32 m_1, m_2;
924 
925         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
926         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
927         put_unaligned_be32(m_1, page_virt);
928         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
929         put_unaligned_be32(m_2, page_virt);
930         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
931 }
932 
933 void ecryptfs_write_crypt_stat_flags(char *page_virt,
934                                      struct ecryptfs_crypt_stat *crypt_stat,
935                                      size_t *written)
936 {
937         u32 flags = 0;
938         int i;
939 
940         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
941                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
942                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
943                         flags |= ecryptfs_flag_map[i].file_flag;
944         /* Version is in top 8 bits of the 32-bit flag vector */
945         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
946         put_unaligned_be32(flags, page_virt);
947         (*written) = 4;
948 }
949 
950 struct ecryptfs_cipher_code_str_map_elem {
951         char cipher_str[16];
952         u8 cipher_code;
953 };
954 
955 /* Add support for additional ciphers by adding elements here. The
956  * cipher_code is whatever OpenPGP applicatoins use to identify the
957  * ciphers. List in order of probability. */
958 static struct ecryptfs_cipher_code_str_map_elem
959 ecryptfs_cipher_code_str_map[] = {
960         {"aes",RFC2440_CIPHER_AES_128 },
961         {"blowfish", RFC2440_CIPHER_BLOWFISH},
962         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
963         {"cast5", RFC2440_CIPHER_CAST_5},
964         {"twofish", RFC2440_CIPHER_TWOFISH},
965         {"cast6", RFC2440_CIPHER_CAST_6},
966         {"aes", RFC2440_CIPHER_AES_192},
967         {"aes", RFC2440_CIPHER_AES_256}
968 };
969 
970 /**
971  * ecryptfs_code_for_cipher_string
972  * @cipher_name: The string alias for the cipher
973  * @key_bytes: Length of key in bytes; used for AES code selection
974  *
975  * Returns zero on no match, or the cipher code on match
976  */
977 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
978 {
979         int i;
980         u8 code = 0;
981         struct ecryptfs_cipher_code_str_map_elem *map =
982                 ecryptfs_cipher_code_str_map;
983 
984         if (strcmp(cipher_name, "aes") == 0) {
985                 switch (key_bytes) {
986                 case 16:
987                         code = RFC2440_CIPHER_AES_128;
988                         break;
989                 case 24:
990                         code = RFC2440_CIPHER_AES_192;
991                         break;
992                 case 32:
993                         code = RFC2440_CIPHER_AES_256;
994                 }
995         } else {
996                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
997                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
998                                 code = map[i].cipher_code;
999                                 break;
1000                         }
1001         }
1002         return code;
1003 }
1004 
1005 /**
1006  * ecryptfs_cipher_code_to_string
1007  * @str: Destination to write out the cipher name
1008  * @cipher_code: The code to convert to cipher name string
1009  *
1010  * Returns zero on success
1011  */
1012 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1013 {
1014         int rc = 0;
1015         int i;
1016 
1017         str[0] = '\0';
1018         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1019                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1020                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1021         if (str[0] == '\0') {
1022                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1023                                 "[%d]\n", cipher_code);
1024                 rc = -EINVAL;
1025         }
1026         return rc;
1027 }
1028 
1029 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1030 {
1031         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1032         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1033         int rc;
1034 
1035         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1036                                  inode);
1037         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1038                 return rc >= 0 ? -EINVAL : rc;
1039         rc = ecryptfs_validate_marker(marker);
1040         if (!rc)
1041                 ecryptfs_i_size_init(file_size, inode);
1042         return rc;
1043 }
1044 
1045 void
1046 ecryptfs_write_header_metadata(char *virt,
1047                                struct ecryptfs_crypt_stat *crypt_stat,
1048                                size_t *written)
1049 {
1050         u32 header_extent_size;
1051         u16 num_header_extents_at_front;
1052 
1053         header_extent_size = (u32)crypt_stat->extent_size;
1054         num_header_extents_at_front =
1055                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1056         put_unaligned_be32(header_extent_size, virt);
1057         virt += 4;
1058         put_unaligned_be16(num_header_extents_at_front, virt);
1059         (*written) = 6;
1060 }
1061 
1062 struct kmem_cache *ecryptfs_header_cache;
1063 
1064 /**
1065  * ecryptfs_write_headers_virt
1066  * @page_virt: The virtual address to write the headers to
1067  * @max: The size of memory allocated at page_virt
1068  * @size: Set to the number of bytes written by this function
1069  * @crypt_stat: The cryptographic context
1070  * @ecryptfs_dentry: The eCryptfs dentry
1071  *
1072  * Format version: 1
1073  *
1074  *   Header Extent:
1075  *     Octets 0-7:        Unencrypted file size (big-endian)
1076  *     Octets 8-15:       eCryptfs special marker
1077  *     Octets 16-19:      Flags
1078  *      Octet 16:         File format version number (between 0 and 255)
1079  *      Octets 17-18:     Reserved
1080  *      Octet 19:         Bit 1 (lsb): Reserved
1081  *                        Bit 2: Encrypted?
1082  *                        Bits 3-8: Reserved
1083  *     Octets 20-23:      Header extent size (big-endian)
1084  *     Octets 24-25:      Number of header extents at front of file
1085  *                        (big-endian)
1086  *     Octet  26:         Begin RFC 2440 authentication token packet set
1087  *   Data Extent 0:
1088  *     Lower data (CBC encrypted)
1089  *   Data Extent 1:
1090  *     Lower data (CBC encrypted)
1091  *   ...
1092  *
1093  * Returns zero on success
1094  */
1095 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1096                                        size_t *size,
1097                                        struct ecryptfs_crypt_stat *crypt_stat,
1098                                        struct dentry *ecryptfs_dentry)
1099 {
1100         int rc;
1101         size_t written;
1102         size_t offset;
1103 
1104         offset = ECRYPTFS_FILE_SIZE_BYTES;
1105         write_ecryptfs_marker((page_virt + offset), &written);
1106         offset += written;
1107         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1108                                         &written);
1109         offset += written;
1110         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1111                                        &written);
1112         offset += written;
1113         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1114                                               ecryptfs_dentry, &written,
1115                                               max - offset);
1116         if (rc)
1117                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1118                                 "set; rc = [%d]\n", rc);
1119         if (size) {
1120                 offset += written;
1121                 *size = offset;
1122         }
1123         return rc;
1124 }
1125 
1126 static int
1127 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1128                                     char *virt, size_t virt_len)
1129 {
1130         int rc;
1131 
1132         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1133                                   0, virt_len);
1134         if (rc < 0)
1135                 printk(KERN_ERR "%s: Error attempting to write header "
1136                        "information to lower file; rc = [%d]\n", __func__, rc);
1137         else
1138                 rc = 0;
1139         return rc;
1140 }
1141 
1142 static int
1143 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1144                                  char *page_virt, size_t size)
1145 {
1146         int rc;
1147 
1148         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1149                                size, 0);
1150         return rc;
1151 }
1152 
1153 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1154                                                unsigned int order)
1155 {
1156         struct page *page;
1157 
1158         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1159         if (page)
1160                 return (unsigned long) page_address(page);
1161         return 0;
1162 }
1163 
1164 /**
1165  * ecryptfs_write_metadata
1166  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1167  * @ecryptfs_inode: The newly created eCryptfs inode
1168  *
1169  * Write the file headers out.  This will likely involve a userspace
1170  * callout, in which the session key is encrypted with one or more
1171  * public keys and/or the passphrase necessary to do the encryption is
1172  * retrieved via a prompt.  Exactly what happens at this point should
1173  * be policy-dependent.
1174  *
1175  * Returns zero on success; non-zero on error
1176  */
1177 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1178                             struct inode *ecryptfs_inode)
1179 {
1180         struct ecryptfs_crypt_stat *crypt_stat =
1181                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1182         unsigned int order;
1183         char *virt;
1184         size_t virt_len;
1185         size_t size = 0;
1186         int rc = 0;
1187 
1188         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1189                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1190                         printk(KERN_ERR "Key is invalid; bailing out\n");
1191                         rc = -EINVAL;
1192                         goto out;
1193                 }
1194         } else {
1195                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1196                        __func__);
1197                 rc = -EINVAL;
1198                 goto out;
1199         }
1200         virt_len = crypt_stat->metadata_size;
1201         order = get_order(virt_len);
1202         /* Released in this function */
1203         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1204         if (!virt) {
1205                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1206                 rc = -ENOMEM;
1207                 goto out;
1208         }
1209         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1210         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1211                                          ecryptfs_dentry);
1212         if (unlikely(rc)) {
1213                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1214                        __func__, rc);
1215                 goto out_free;
1216         }
1217         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1218                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1219                                                       size);
1220         else
1221                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1222                                                          virt_len);
1223         if (rc) {
1224                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1225                        "rc = [%d]\n", __func__, rc);
1226                 goto out_free;
1227         }
1228 out_free:
1229         free_pages((unsigned long)virt, order);
1230 out:
1231         return rc;
1232 }
1233 
1234 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1235 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1236 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1237                                  char *virt, int *bytes_read,
1238                                  int validate_header_size)
1239 {
1240         int rc = 0;
1241         u32 header_extent_size;
1242         u16 num_header_extents_at_front;
1243 
1244         header_extent_size = get_unaligned_be32(virt);
1245         virt += sizeof(__be32);
1246         num_header_extents_at_front = get_unaligned_be16(virt);
1247         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1248                                      * (size_t)header_extent_size));
1249         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1250         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1251             && (crypt_stat->metadata_size
1252                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1253                 rc = -EINVAL;
1254                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1255                        crypt_stat->metadata_size);
1256         }
1257         return rc;
1258 }
1259 
1260 /**
1261  * set_default_header_data
1262  * @crypt_stat: The cryptographic context
1263  *
1264  * For version 0 file format; this function is only for backwards
1265  * compatibility for files created with the prior versions of
1266  * eCryptfs.
1267  */
1268 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1269 {
1270         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1271 }
1272 
1273 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1274 {
1275         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1276         struct ecryptfs_crypt_stat *crypt_stat;
1277         u64 file_size;
1278 
1279         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1280         mount_crypt_stat =
1281                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1282         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1283                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1284                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1285                         file_size += crypt_stat->metadata_size;
1286         } else
1287                 file_size = get_unaligned_be64(page_virt);
1288         i_size_write(inode, (loff_t)file_size);
1289         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1290 }
1291 
1292 /**
1293  * ecryptfs_read_headers_virt
1294  * @page_virt: The virtual address into which to read the headers
1295  * @crypt_stat: The cryptographic context
1296  * @ecryptfs_dentry: The eCryptfs dentry
1297  * @validate_header_size: Whether to validate the header size while reading
1298  *
1299  * Read/parse the header data. The header format is detailed in the
1300  * comment block for the ecryptfs_write_headers_virt() function.
1301  *
1302  * Returns zero on success
1303  */
1304 static int ecryptfs_read_headers_virt(char *page_virt,
1305                                       struct ecryptfs_crypt_stat *crypt_stat,
1306                                       struct dentry *ecryptfs_dentry,
1307                                       int validate_header_size)
1308 {
1309         int rc = 0;
1310         int offset;
1311         int bytes_read;
1312 
1313         ecryptfs_set_default_sizes(crypt_stat);
1314         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1315                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1316         offset = ECRYPTFS_FILE_SIZE_BYTES;
1317         rc = ecryptfs_validate_marker(page_virt + offset);
1318         if (rc)
1319                 goto out;
1320         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1321                 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1322         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1323         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1324                                     &bytes_read);
1325         if (rc) {
1326                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1327                 goto out;
1328         }
1329         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1330                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1331                                 "file version [%d] is supported by this "
1332                                 "version of eCryptfs\n",
1333                                 crypt_stat->file_version,
1334                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1335                 rc = -EINVAL;
1336                 goto out;
1337         }
1338         offset += bytes_read;
1339         if (crypt_stat->file_version >= 1) {
1340                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1341                                            &bytes_read, validate_header_size);
1342                 if (rc) {
1343                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1344                                         "metadata; rc = [%d]\n", rc);
1345                 }
1346                 offset += bytes_read;
1347         } else
1348                 set_default_header_data(crypt_stat);
1349         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1350                                        ecryptfs_dentry);
1351 out:
1352         return rc;
1353 }
1354 
1355 /**
1356  * ecryptfs_read_xattr_region
1357  * @page_virt: The vitual address into which to read the xattr data
1358  * @ecryptfs_inode: The eCryptfs inode
1359  *
1360  * Attempts to read the crypto metadata from the extended attribute
1361  * region of the lower file.
1362  *
1363  * Returns zero on success; non-zero on error
1364  */
1365 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1366 {
1367         struct dentry *lower_dentry =
1368                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1369         ssize_t size;
1370         int rc = 0;
1371 
1372         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1373                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1374         if (size < 0) {
1375                 if (unlikely(ecryptfs_verbosity > 0))
1376                         printk(KERN_INFO "Error attempting to read the [%s] "
1377                                "xattr from the lower file; return value = "
1378                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1379                 rc = -EINVAL;
1380                 goto out;
1381         }
1382 out:
1383         return rc;
1384 }
1385 
1386 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1387                                             struct inode *inode)
1388 {
1389         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1390         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1391         int rc;
1392 
1393         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1394                                      ECRYPTFS_XATTR_NAME, file_size,
1395                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1396         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1397                 return rc >= 0 ? -EINVAL : rc;
1398         rc = ecryptfs_validate_marker(marker);
1399         if (!rc)
1400                 ecryptfs_i_size_init(file_size, inode);
1401         return rc;
1402 }
1403 
1404 /**
1405  * ecryptfs_read_metadata
1406  *
1407  * Common entry point for reading file metadata. From here, we could
1408  * retrieve the header information from the header region of the file,
1409  * the xattr region of the file, or some other repostory that is
1410  * stored separately from the file itself. The current implementation
1411  * supports retrieving the metadata information from the file contents
1412  * and from the xattr region.
1413  *
1414  * Returns zero if valid headers found and parsed; non-zero otherwise
1415  */
1416 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1417 {
1418         int rc;
1419         char *page_virt;
1420         struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1421         struct ecryptfs_crypt_stat *crypt_stat =
1422             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1423         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1424                 &ecryptfs_superblock_to_private(
1425                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1426 
1427         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1428                                                       mount_crypt_stat);
1429         /* Read the first page from the underlying file */
1430         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1431         if (!page_virt) {
1432                 rc = -ENOMEM;
1433                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1434                        __func__);
1435                 goto out;
1436         }
1437         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1438                                  ecryptfs_inode);
1439         if (rc >= 0)
1440                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1441                                                 ecryptfs_dentry,
1442                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1443         if (rc) {
1444                 /* metadata is not in the file header, so try xattrs */
1445                 memset(page_virt, 0, PAGE_SIZE);
1446                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1447                 if (rc) {
1448                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1449                                "file header region or xattr region, inode %lu\n",
1450                                 ecryptfs_inode->i_ino);
1451                         rc = -EINVAL;
1452                         goto out;
1453                 }
1454                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1455                                                 ecryptfs_dentry,
1456                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1457                 if (rc) {
1458                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1459                                "file xattr region either, inode %lu\n",
1460                                 ecryptfs_inode->i_ino);
1461                         rc = -EINVAL;
1462                 }
1463                 if (crypt_stat->mount_crypt_stat->flags
1464                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1465                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1466                 } else {
1467                         printk(KERN_WARNING "Attempt to access file with "
1468                                "crypto metadata only in the extended attribute "
1469                                "region, but eCryptfs was mounted without "
1470                                "xattr support enabled. eCryptfs will not treat "
1471                                "this like an encrypted file, inode %lu\n",
1472                                 ecryptfs_inode->i_ino);
1473                         rc = -EINVAL;
1474                 }
1475         }
1476 out:
1477         if (page_virt) {
1478                 memset(page_virt, 0, PAGE_SIZE);
1479                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1480         }
1481         return rc;
1482 }
1483 
1484 /**
1485  * ecryptfs_encrypt_filename - encrypt filename
1486  *
1487  * CBC-encrypts the filename. We do not want to encrypt the same
1488  * filename with the same key and IV, which may happen with hard
1489  * links, so we prepend random bits to each filename.
1490  *
1491  * Returns zero on success; non-zero otherwise
1492  */
1493 static int
1494 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1495                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1496 {
1497         int rc = 0;
1498 
1499         filename->encrypted_filename = NULL;
1500         filename->encrypted_filename_size = 0;
1501         if (mount_crypt_stat && (mount_crypt_stat->flags
1502                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1503                 size_t packet_size;
1504                 size_t remaining_bytes;
1505 
1506                 rc = ecryptfs_write_tag_70_packet(
1507                         NULL, NULL,
1508                         &filename->encrypted_filename_size,
1509                         mount_crypt_stat, NULL,
1510                         filename->filename_size);
1511                 if (rc) {
1512                         printk(KERN_ERR "%s: Error attempting to get packet "
1513                                "size for tag 72; rc = [%d]\n", __func__,
1514                                rc);
1515                         filename->encrypted_filename_size = 0;
1516                         goto out;
1517                 }
1518                 filename->encrypted_filename =
1519                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1520                 if (!filename->encrypted_filename) {
1521                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1522                                "to kmalloc [%zd] bytes\n", __func__,
1523                                filename->encrypted_filename_size);
1524                         rc = -ENOMEM;
1525                         goto out;
1526                 }
1527                 remaining_bytes = filename->encrypted_filename_size;
1528                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1529                                                   &remaining_bytes,
1530                                                   &packet_size,
1531                                                   mount_crypt_stat,
1532                                                   filename->filename,
1533                                                   filename->filename_size);
1534                 if (rc) {
1535                         printk(KERN_ERR "%s: Error attempting to generate "
1536                                "tag 70 packet; rc = [%d]\n", __func__,
1537                                rc);
1538                         kfree(filename->encrypted_filename);
1539                         filename->encrypted_filename = NULL;
1540                         filename->encrypted_filename_size = 0;
1541                         goto out;
1542                 }
1543                 filename->encrypted_filename_size = packet_size;
1544         } else {
1545                 printk(KERN_ERR "%s: No support for requested filename "
1546                        "encryption method in this release\n", __func__);
1547                 rc = -EOPNOTSUPP;
1548                 goto out;
1549         }
1550 out:
1551         return rc;
1552 }
1553 
1554 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1555                                   const char *name, size_t name_size)
1556 {
1557         int rc = 0;
1558 
1559         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1560         if (!(*copied_name)) {
1561                 rc = -ENOMEM;
1562                 goto out;
1563         }
1564         memcpy((void *)(*copied_name), (void *)name, name_size);
1565         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1566                                                  * in printing out the
1567                                                  * string in debug
1568                                                  * messages */
1569         (*copied_name_size) = name_size;
1570 out:
1571         return rc;
1572 }
1573 
1574 /**
1575  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1576  * @key_tfm: Crypto context for key material, set by this function
1577  * @cipher_name: Name of the cipher
1578  * @key_size: Size of the key in bytes
1579  *
1580  * Returns zero on success. Any crypto_tfm structs allocated here
1581  * should be released by other functions, such as on a superblock put
1582  * event, regardless of whether this function succeeds for fails.
1583  */
1584 static int
1585 ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1586                             char *cipher_name, size_t *key_size)
1587 {
1588         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1589         char *full_alg_name = NULL;
1590         int rc;
1591 
1592         *key_tfm = NULL;
1593         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1594                 rc = -EINVAL;
1595                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1596                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1597                 goto out;
1598         }
1599         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1600                                                     "ecb");
1601         if (rc)
1602                 goto out;
1603         *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1604         if (IS_ERR(*key_tfm)) {
1605                 rc = PTR_ERR(*key_tfm);
1606                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1607                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1608                 goto out;
1609         }
1610         crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1611         if (*key_size == 0)
1612                 *key_size = crypto_skcipher_default_keysize(*key_tfm);
1613         get_random_bytes(dummy_key, *key_size);
1614         rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1615         if (rc) {
1616                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1617                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1618                        rc);
1619                 rc = -EINVAL;
1620                 goto out;
1621         }
1622 out:
1623         kfree(full_alg_name);
1624         return rc;
1625 }
1626 
1627 struct kmem_cache *ecryptfs_key_tfm_cache;
1628 static struct list_head key_tfm_list;
1629 struct mutex key_tfm_list_mutex;
1630 
1631 int __init ecryptfs_init_crypto(void)
1632 {
1633         mutex_init(&key_tfm_list_mutex);
1634         INIT_LIST_HEAD(&key_tfm_list);
1635         return 0;
1636 }
1637 
1638 /**
1639  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1640  *
1641  * Called only at module unload time
1642  */
1643 int ecryptfs_destroy_crypto(void)
1644 {
1645         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1646 
1647         mutex_lock(&key_tfm_list_mutex);
1648         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1649                                  key_tfm_list) {
1650                 list_del(&key_tfm->key_tfm_list);
1651                 crypto_free_skcipher(key_tfm->key_tfm);
1652                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1653         }
1654         mutex_unlock(&key_tfm_list_mutex);
1655         return 0;
1656 }
1657 
1658 int
1659 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1660                          size_t key_size)
1661 {
1662         struct ecryptfs_key_tfm *tmp_tfm;
1663         int rc = 0;
1664 
1665         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1666 
1667         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1668         if (key_tfm != NULL)
1669                 (*key_tfm) = tmp_tfm;
1670         if (!tmp_tfm) {
1671                 rc = -ENOMEM;
1672                 printk(KERN_ERR "Error attempting to allocate from "
1673                        "ecryptfs_key_tfm_cache\n");
1674                 goto out;
1675         }
1676         mutex_init(&tmp_tfm->key_tfm_mutex);
1677         strncpy(tmp_tfm->cipher_name, cipher_name,
1678                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1679         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1680         tmp_tfm->key_size = key_size;
1681         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1682                                          tmp_tfm->cipher_name,
1683                                          &tmp_tfm->key_size);
1684         if (rc) {
1685                 printk(KERN_ERR "Error attempting to initialize key TFM "
1686                        "cipher with name = [%s]; rc = [%d]\n",
1687                        tmp_tfm->cipher_name, rc);
1688                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1689                 if (key_tfm != NULL)
1690                         (*key_tfm) = NULL;
1691                 goto out;
1692         }
1693         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1694 out:
1695         return rc;
1696 }
1697 
1698 /**
1699  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1700  * @cipher_name: the name of the cipher to search for
1701  * @key_tfm: set to corresponding tfm if found
1702  *
1703  * Searches for cached key_tfm matching @cipher_name
1704  * Must be called with &key_tfm_list_mutex held
1705  * Returns 1 if found, with @key_tfm set
1706  * Returns 0 if not found, with @key_tfm set to NULL
1707  */
1708 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1709 {
1710         struct ecryptfs_key_tfm *tmp_key_tfm;
1711 
1712         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1713 
1714         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1715                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1716                         if (key_tfm)
1717                                 (*key_tfm) = tmp_key_tfm;
1718                         return 1;
1719                 }
1720         }
1721         if (key_tfm)
1722                 (*key_tfm) = NULL;
1723         return 0;
1724 }
1725 
1726 /**
1727  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1728  *
1729  * @tfm: set to cached tfm found, or new tfm created
1730  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1731  * @cipher_name: the name of the cipher to search for and/or add
1732  *
1733  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1734  * Searches for cached item first, and creates new if not found.
1735  * Returns 0 on success, non-zero if adding new cipher failed
1736  */
1737 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1738                                                struct mutex **tfm_mutex,
1739                                                char *cipher_name)
1740 {
1741         struct ecryptfs_key_tfm *key_tfm;
1742         int rc = 0;
1743 
1744         (*tfm) = NULL;
1745         (*tfm_mutex) = NULL;
1746 
1747         mutex_lock(&key_tfm_list_mutex);
1748         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1749                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1750                 if (rc) {
1751                         printk(KERN_ERR "Error adding new key_tfm to list; "
1752                                         "rc = [%d]\n", rc);
1753                         goto out;
1754                 }
1755         }
1756         (*tfm) = key_tfm->key_tfm;
1757         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1758 out:
1759         mutex_unlock(&key_tfm_list_mutex);
1760         return rc;
1761 }
1762 
1763 /* 64 characters forming a 6-bit target field */
1764 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1765                                                  "EFGHIJKLMNOPQRST"
1766                                                  "UVWXYZabcdefghij"
1767                                                  "klmnopqrstuvwxyz");
1768 
1769 /* We could either offset on every reverse map or just pad some 0x00's
1770  * at the front here */
1771 static const unsigned char filename_rev_map[256] = {
1772         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1773         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1774         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1775         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1776         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1777         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1778         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1779         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1780         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1781         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1782         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1783         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1784         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1785         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1786         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1787         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1788 };
1789 
1790 /**
1791  * ecryptfs_encode_for_filename
1792  * @dst: Destination location for encoded filename
1793  * @dst_size: Size of the encoded filename in bytes
1794  * @src: Source location for the filename to encode
1795  * @src_size: Size of the source in bytes
1796  */
1797 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1798                                   unsigned char *src, size_t src_size)
1799 {
1800         size_t num_blocks;
1801         size_t block_num = 0;
1802         size_t dst_offset = 0;
1803         unsigned char last_block[3];
1804 
1805         if (src_size == 0) {
1806                 (*dst_size) = 0;
1807                 goto out;
1808         }
1809         num_blocks = (src_size / 3);
1810         if ((src_size % 3) == 0) {
1811                 memcpy(last_block, (&src[src_size - 3]), 3);
1812         } else {
1813                 num_blocks++;
1814                 last_block[2] = 0x00;
1815                 switch (src_size % 3) {
1816                 case 1:
1817                         last_block[0] = src[src_size - 1];
1818                         last_block[1] = 0x00;
1819                         break;
1820                 case 2:
1821                         last_block[0] = src[src_size - 2];
1822                         last_block[1] = src[src_size - 1];
1823                 }
1824         }
1825         (*dst_size) = (num_blocks * 4);
1826         if (!dst)
1827                 goto out;
1828         while (block_num < num_blocks) {
1829                 unsigned char *src_block;
1830                 unsigned char dst_block[4];
1831 
1832                 if (block_num == (num_blocks - 1))
1833                         src_block = last_block;
1834                 else
1835                         src_block = &src[block_num * 3];
1836                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1837                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1838                                 | ((src_block[1] >> 4) & 0x0F));
1839                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1840                                 | ((src_block[2] >> 6) & 0x03));
1841                 dst_block[3] = (src_block[2] & 0x3F);
1842                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1843                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1844                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1845                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1846                 block_num++;
1847         }
1848 out:
1849         return;
1850 }
1851 
1852 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1853 {
1854         /* Not exact; conservatively long. Every block of 4
1855          * encoded characters decodes into a block of 3
1856          * decoded characters. This segment of code provides
1857          * the caller with the maximum amount of allocated
1858          * space that @dst will need to point to in a
1859          * subsequent call. */
1860         return ((encoded_size + 1) * 3) / 4;
1861 }
1862 
1863 /**
1864  * ecryptfs_decode_from_filename
1865  * @dst: If NULL, this function only sets @dst_size and returns. If
1866  *       non-NULL, this function decodes the encoded octets in @src
1867  *       into the memory that @dst points to.
1868  * @dst_size: Set to the size of the decoded string.
1869  * @src: The encoded set of octets to decode.
1870  * @src_size: The size of the encoded set of octets to decode.
1871  */
1872 static void
1873 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1874                               const unsigned char *src, size_t src_size)
1875 {
1876         u8 current_bit_offset = 0;
1877         size_t src_byte_offset = 0;
1878         size_t dst_byte_offset = 0;
1879 
1880         if (dst == NULL) {
1881                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1882                 goto out;
1883         }
1884         while (src_byte_offset < src_size) {
1885                 unsigned char src_byte =
1886                                 filename_rev_map[(int)src[src_byte_offset]];
1887 
1888                 switch (current_bit_offset) {
1889                 case 0:
1890                         dst[dst_byte_offset] = (src_byte << 2);
1891                         current_bit_offset = 6;
1892                         break;
1893                 case 6:
1894                         dst[dst_byte_offset++] |= (src_byte >> 4);
1895                         dst[dst_byte_offset] = ((src_byte & 0xF)
1896                                                  << 4);
1897                         current_bit_offset = 4;
1898                         break;
1899                 case 4:
1900                         dst[dst_byte_offset++] |= (src_byte >> 2);
1901                         dst[dst_byte_offset] = (src_byte << 6);
1902                         current_bit_offset = 2;
1903                         break;
1904                 case 2:
1905                         dst[dst_byte_offset++] |= (src_byte);
1906                         current_bit_offset = 0;
1907                         break;
1908                 }
1909                 src_byte_offset++;
1910         }
1911         (*dst_size) = dst_byte_offset;
1912 out:
1913         return;
1914 }
1915 
1916 /**
1917  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1918  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1919  * @name: The plaintext name
1920  * @length: The length of the plaintext
1921  * @encoded_name: The encypted name
1922  *
1923  * Encrypts and encodes a filename into something that constitutes a
1924  * valid filename for a filesystem, with printable characters.
1925  *
1926  * We assume that we have a properly initialized crypto context,
1927  * pointed to by crypt_stat->tfm.
1928  *
1929  * Returns zero on success; non-zero on otherwise
1930  */
1931 int ecryptfs_encrypt_and_encode_filename(
1932         char **encoded_name,
1933         size_t *encoded_name_size,
1934         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1935         const char *name, size_t name_size)
1936 {
1937         size_t encoded_name_no_prefix_size;
1938         int rc = 0;
1939 
1940         (*encoded_name) = NULL;
1941         (*encoded_name_size) = 0;
1942         if (mount_crypt_stat && (mount_crypt_stat->flags
1943                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1944                 struct ecryptfs_filename *filename;
1945 
1946                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1947                 if (!filename) {
1948                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1949                                "to kzalloc [%zd] bytes\n", __func__,
1950                                sizeof(*filename));
1951                         rc = -ENOMEM;
1952                         goto out;
1953                 }
1954                 filename->filename = (char *)name;
1955                 filename->filename_size = name_size;
1956                 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1957                 if (rc) {
1958                         printk(KERN_ERR "%s: Error attempting to encrypt "
1959                                "filename; rc = [%d]\n", __func__, rc);
1960                         kfree(filename);
1961                         goto out;
1962                 }
1963                 ecryptfs_encode_for_filename(
1964                         NULL, &encoded_name_no_prefix_size,
1965                         filename->encrypted_filename,
1966                         filename->encrypted_filename_size);
1967                 if (mount_crypt_stat
1968                         && (mount_crypt_stat->flags
1969                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1970                         (*encoded_name_size) =
1971                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1972                                  + encoded_name_no_prefix_size);
1973                 else
1974                         (*encoded_name_size) =
1975                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1976                                  + encoded_name_no_prefix_size);
1977                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1978                 if (!(*encoded_name)) {
1979                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1980                                "to kzalloc [%zd] bytes\n", __func__,
1981                                (*encoded_name_size));
1982                         rc = -ENOMEM;
1983                         kfree(filename->encrypted_filename);
1984                         kfree(filename);
1985                         goto out;
1986                 }
1987                 if (mount_crypt_stat
1988                         && (mount_crypt_stat->flags
1989                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1990                         memcpy((*encoded_name),
1991                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1992                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1993                         ecryptfs_encode_for_filename(
1994                             ((*encoded_name)
1995                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1996                             &encoded_name_no_prefix_size,
1997                             filename->encrypted_filename,
1998                             filename->encrypted_filename_size);
1999                         (*encoded_name_size) =
2000                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2001                                  + encoded_name_no_prefix_size);
2002                         (*encoded_name)[(*encoded_name_size)] = '\0';
2003                 } else {
2004                         rc = -EOPNOTSUPP;
2005                 }
2006                 if (rc) {
2007                         printk(KERN_ERR "%s: Error attempting to encode "
2008                                "encrypted filename; rc = [%d]\n", __func__,
2009                                rc);
2010                         kfree((*encoded_name));
2011                         (*encoded_name) = NULL;
2012                         (*encoded_name_size) = 0;
2013                 }
2014                 kfree(filename->encrypted_filename);
2015                 kfree(filename);
2016         } else {
2017                 rc = ecryptfs_copy_filename(encoded_name,
2018                                             encoded_name_size,
2019                                             name, name_size);
2020         }
2021 out:
2022         return rc;
2023 }
2024 
2025 /**
2026  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2027  * @plaintext_name: The plaintext name
2028  * @plaintext_name_size: The plaintext name size
2029  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2030  * @name: The filename in cipher text
2031  * @name_size: The cipher text name size
2032  *
2033  * Decrypts and decodes the filename.
2034  *
2035  * Returns zero on error; non-zero otherwise
2036  */
2037 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2038                                          size_t *plaintext_name_size,
2039                                          struct super_block *sb,
2040                                          const char *name, size_t name_size)
2041 {
2042         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2043                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2044         char *decoded_name;
2045         size_t decoded_name_size;
2046         size_t packet_size;
2047         int rc = 0;
2048 
2049         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2050             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2051             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2052             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2053                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2054                 const char *orig_name = name;
2055                 size_t orig_name_size = name_size;
2056 
2057                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2058                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2059                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2060                                               name, name_size);
2061                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2062                 if (!decoded_name) {
2063                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2064                                "to kmalloc [%zd] bytes\n", __func__,
2065                                decoded_name_size);
2066                         rc = -ENOMEM;
2067                         goto out;
2068                 }
2069                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2070                                               name, name_size);
2071                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2072                                                   plaintext_name_size,
2073                                                   &packet_size,
2074                                                   mount_crypt_stat,
2075                                                   decoded_name,
2076                                                   decoded_name_size);
2077                 if (rc) {
2078                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2079                                "from filename; copying through filename "
2080                                "as-is\n", __func__);
2081                         rc = ecryptfs_copy_filename(plaintext_name,
2082                                                     plaintext_name_size,
2083                                                     orig_name, orig_name_size);
2084                         goto out_free;
2085                 }
2086         } else {
2087                 rc = ecryptfs_copy_filename(plaintext_name,
2088                                             plaintext_name_size,
2089                                             name, name_size);
2090                 goto out;
2091         }
2092 out_free:
2093         kfree(decoded_name);
2094 out:
2095         return rc;
2096 }
2097 
2098 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2099 
2100 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2101                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2102 {
2103         struct crypto_skcipher *tfm;
2104         struct mutex *tfm_mutex;
2105         size_t cipher_blocksize;
2106         int rc;
2107 
2108         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2109                 (*namelen) = lower_namelen;
2110                 return 0;
2111         }
2112 
2113         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2114                         mount_crypt_stat->global_default_fn_cipher_name);
2115         if (unlikely(rc)) {
2116                 (*namelen) = 0;
2117                 return rc;
2118         }
2119 
2120         mutex_lock(tfm_mutex);
2121         cipher_blocksize = crypto_skcipher_blocksize(tfm);
2122         mutex_unlock(tfm_mutex);
2123 
2124         /* Return an exact amount for the common cases */
2125         if (lower_namelen == NAME_MAX
2126             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2127                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2128                 return 0;
2129         }
2130 
2131         /* Return a safe estimate for the uncommon cases */
2132         (*namelen) = lower_namelen;
2133         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2134         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2135         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2136         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2137         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2138         /* Worst case is that the filename is padded nearly a full block size */
2139         (*namelen) -= cipher_blocksize - 1;
2140 
2141         if ((*namelen) < 0)
2142                 (*namelen) = 0;
2143 
2144         return 0;
2145 }
2146 

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