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

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