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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 <linux/fs.h>
 27 #include <linux/mount.h>
 28 #include <linux/pagemap.h>
 29 #include <linux/random.h>
 30 #include <linux/compiler.h>
 31 #include <linux/key.h>
 32 #include <linux/namei.h>
 33 #include <linux/crypto.h>
 34 #include <linux/file.h>
 35 #include <linux/scatterlist.h>
 36 #include <linux/slab.h>
 37 #include <asm/unaligned.h>
 38 #include "ecryptfs_kernel.h"
 39 
 40 #define DECRYPT         0
 41 #define ENCRYPT         1
 42 
 43 /**
 44  * ecryptfs_to_hex
 45  * @dst: Buffer to take hex character representation of contents of
 46  *       src; must be at least of size (src_size * 2)
 47  * @src: Buffer to be converted to a hex string respresentation
 48  * @src_size: number of bytes to convert
 49  */
 50 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
 51 {
 52         int x;
 53 
 54         for (x = 0; x < src_size; x++)
 55                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
 56 }
 57 
 58 /**
 59  * ecryptfs_from_hex
 60  * @dst: Buffer to take the bytes from src hex; must be at least of
 61  *       size (src_size / 2)
 62  * @src: Buffer to be converted from a hex string respresentation to raw value
 63  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
 64  */
 65 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
 66 {
 67         int x;
 68         char tmp[3] = { 0, };
 69 
 70         for (x = 0; x < dst_size; x++) {
 71                 tmp[0] = src[x * 2];
 72                 tmp[1] = src[x * 2 + 1];
 73                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
 74         }
 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 scatterlist sg;
 92         struct hash_desc desc = {
 93                 .tfm = crypt_stat->hash_tfm,
 94                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 95         };
 96         int rc = 0;
 97 
 98         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
 99         sg_init_one(&sg, (u8 *)src, len);
100         if (!desc.tfm) {
101                 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
102                                              CRYPTO_ALG_ASYNC);
103                 if (IS_ERR(desc.tfm)) {
104                         rc = PTR_ERR(desc.tfm);
105                         ecryptfs_printk(KERN_ERR, "Error attempting to "
106                                         "allocate crypto context; rc = [%d]\n",
107                                         rc);
108                         goto out;
109                 }
110                 crypt_stat->hash_tfm = desc.tfm;
111         }
112         rc = crypto_hash_init(&desc);
113         if (rc) {
114                 printk(KERN_ERR
115                        "%s: Error initializing crypto hash; rc = [%d]\n",
116                        __func__, rc);
117                 goto out;
118         }
119         rc = crypto_hash_update(&desc, &sg, len);
120         if (rc) {
121                 printk(KERN_ERR
122                        "%s: Error updating crypto hash; rc = [%d]\n",
123                        __func__, rc);
124                 goto out;
125         }
126         rc = crypto_hash_final(&desc, dst);
127         if (rc) {
128                 printk(KERN_ERR
129                        "%s: Error finalizing crypto hash; rc = [%d]\n",
130                        __func__, rc);
131                 goto out;
132         }
133 out:
134         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
135         return rc;
136 }
137 
138 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
139                                                   char *cipher_name,
140                                                   char *chaining_modifier)
141 {
142         int cipher_name_len = strlen(cipher_name);
143         int chaining_modifier_len = strlen(chaining_modifier);
144         int algified_name_len;
145         int rc;
146 
147         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
148         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
149         if (!(*algified_name)) {
150                 rc = -ENOMEM;
151                 goto out;
152         }
153         snprintf((*algified_name), algified_name_len, "%s(%s)",
154                  chaining_modifier, cipher_name);
155         rc = 0;
156 out:
157         return rc;
158 }
159 
160 /**
161  * ecryptfs_derive_iv
162  * @iv: destination for the derived iv vale
163  * @crypt_stat: Pointer to crypt_stat struct for the current inode
164  * @offset: Offset of the extent whose IV we are to derive
165  *
166  * Generate the initialization vector from the given root IV and page
167  * offset.
168  *
169  * Returns zero on success; non-zero on error.
170  */
171 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
172                        loff_t offset)
173 {
174         int rc = 0;
175         char dst[MD5_DIGEST_SIZE];
176         char src[ECRYPTFS_MAX_IV_BYTES + 16];
177 
178         if (unlikely(ecryptfs_verbosity > 0)) {
179                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
180                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
181         }
182         /* TODO: It is probably secure to just cast the least
183          * significant bits of the root IV into an unsigned long and
184          * add the offset to that rather than go through all this
185          * hashing business. -Halcrow */
186         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
187         memset((src + crypt_stat->iv_bytes), 0, 16);
188         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
189         if (unlikely(ecryptfs_verbosity > 0)) {
190                 ecryptfs_printk(KERN_DEBUG, "source:\n");
191                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
192         }
193         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
194                                     (crypt_stat->iv_bytes + 16));
195         if (rc) {
196                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
197                                 "MD5 while generating IV for a page\n");
198                 goto out;
199         }
200         memcpy(iv, dst, crypt_stat->iv_bytes);
201         if (unlikely(ecryptfs_verbosity > 0)) {
202                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
203                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
204         }
205 out:
206         return rc;
207 }
208 
209 /**
210  * ecryptfs_init_crypt_stat
211  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
212  *
213  * Initialize the crypt_stat structure.
214  */
215 void
216 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
217 {
218         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
219         INIT_LIST_HEAD(&crypt_stat->keysig_list);
220         mutex_init(&crypt_stat->keysig_list_mutex);
221         mutex_init(&crypt_stat->cs_mutex);
222         mutex_init(&crypt_stat->cs_tfm_mutex);
223         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
224         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
225 }
226 
227 /**
228  * ecryptfs_destroy_crypt_stat
229  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
230  *
231  * Releases all memory associated with a crypt_stat struct.
232  */
233 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
234 {
235         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
236 
237         if (crypt_stat->tfm)
238                 crypto_free_ablkcipher(crypt_stat->tfm);
239         if (crypt_stat->hash_tfm)
240                 crypto_free_hash(crypt_stat->hash_tfm);
241         list_for_each_entry_safe(key_sig, key_sig_tmp,
242                                  &crypt_stat->keysig_list, crypt_stat_list) {
243                 list_del(&key_sig->crypt_stat_list);
244                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
245         }
246         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
247 }
248 
249 void ecryptfs_destroy_mount_crypt_stat(
250         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
251 {
252         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
253 
254         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
255                 return;
256         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
257         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
258                                  &mount_crypt_stat->global_auth_tok_list,
259                                  mount_crypt_stat_list) {
260                 list_del(&auth_tok->mount_crypt_stat_list);
261                 if (auth_tok->global_auth_tok_key
262                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
263                         key_put(auth_tok->global_auth_tok_key);
264                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
265         }
266         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
267         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
268 }
269 
270 /**
271  * virt_to_scatterlist
272  * @addr: Virtual address
273  * @size: Size of data; should be an even multiple of the block size
274  * @sg: Pointer to scatterlist array; set to NULL to obtain only
275  *      the number of scatterlist structs required in array
276  * @sg_size: Max array size
277  *
278  * Fills in a scatterlist array with page references for a passed
279  * virtual address.
280  *
281  * Returns the number of scatterlist structs in array used
282  */
283 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
284                         int sg_size)
285 {
286         int i = 0;
287         struct page *pg;
288         int offset;
289         int remainder_of_page;
290 
291         sg_init_table(sg, sg_size);
292 
293         while (size > 0 && i < sg_size) {
294                 pg = virt_to_page(addr);
295                 offset = offset_in_page(addr);
296                 sg_set_page(&sg[i], pg, 0, offset);
297                 remainder_of_page = PAGE_CACHE_SIZE - offset;
298                 if (size >= remainder_of_page) {
299                         sg[i].length = remainder_of_page;
300                         addr += remainder_of_page;
301                         size -= remainder_of_page;
302                 } else {
303                         sg[i].length = size;
304                         addr += size;
305                         size = 0;
306                 }
307                 i++;
308         }
309         if (size > 0)
310                 return -ENOMEM;
311         return i;
312 }
313 
314 struct extent_crypt_result {
315         struct completion completion;
316         int rc;
317 };
318 
319 static void extent_crypt_complete(struct crypto_async_request *req, int rc)
320 {
321         struct extent_crypt_result *ecr = req->data;
322 
323         if (rc == -EINPROGRESS)
324                 return;
325 
326         ecr->rc = rc;
327         complete(&ecr->completion);
328 }
329 
330 /**
331  * crypt_scatterlist
332  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
333  * @dst_sg: Destination of the data after performing the crypto operation
334  * @src_sg: Data to be encrypted or decrypted
335  * @size: Length of data
336  * @iv: IV to use
337  * @op: ENCRYPT or DECRYPT to indicate the desired operation
338  *
339  * Returns the number of bytes encrypted or decrypted; negative value on error
340  */
341 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
342                              struct scatterlist *dst_sg,
343                              struct scatterlist *src_sg, int size,
344                              unsigned char *iv, int op)
345 {
346         struct ablkcipher_request *req = NULL;
347         struct extent_crypt_result ecr;
348         int rc = 0;
349 
350         BUG_ON(!crypt_stat || !crypt_stat->tfm
351                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
352         if (unlikely(ecryptfs_verbosity > 0)) {
353                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
354                                 crypt_stat->key_size);
355                 ecryptfs_dump_hex(crypt_stat->key,
356                                   crypt_stat->key_size);
357         }
358 
359         init_completion(&ecr.completion);
360 
361         mutex_lock(&crypt_stat->cs_tfm_mutex);
362         req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
363         if (!req) {
364                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
365                 rc = -ENOMEM;
366                 goto out;
367         }
368 
369         ablkcipher_request_set_callback(req,
370                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
371                         extent_crypt_complete, &ecr);
372         /* Consider doing this once, when the file is opened */
373         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
374                 rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
375                                               crypt_stat->key_size);
376                 if (rc) {
377                         ecryptfs_printk(KERN_ERR,
378                                         "Error setting key; rc = [%d]\n",
379                                         rc);
380                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
381                         rc = -EINVAL;
382                         goto out;
383                 }
384                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
385         }
386         mutex_unlock(&crypt_stat->cs_tfm_mutex);
387         ablkcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
388         rc = op == ENCRYPT ? crypto_ablkcipher_encrypt(req) :
389                              crypto_ablkcipher_decrypt(req);
390         if (rc == -EINPROGRESS || rc == -EBUSY) {
391                 struct extent_crypt_result *ecr = req->base.data;
392 
393                 wait_for_completion(&ecr->completion);
394                 rc = ecr->rc;
395                 INIT_COMPLETION(ecr->completion);
396         }
397 out:
398         ablkcipher_request_free(req);
399         return rc;
400 }
401 
402 /**
403  * lower_offset_for_page
404  *
405  * Convert an eCryptfs page index into a lower byte offset
406  */
407 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
408                                     struct page *page)
409 {
410         return ecryptfs_lower_header_size(crypt_stat) +
411                ((loff_t)page->index << PAGE_CACHE_SHIFT);
412 }
413 
414 /**
415  * crypt_extent
416  * @crypt_stat: crypt_stat containing cryptographic context for the
417  *              encryption operation
418  * @dst_page: The page to write the result into
419  * @src_page: The page to read from
420  * @extent_offset: Page extent offset for use in generating IV
421  * @op: ENCRYPT or DECRYPT to indicate the desired operation
422  *
423  * Encrypts or decrypts one extent of data.
424  *
425  * Return zero on success; non-zero otherwise
426  */
427 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
428                         struct page *dst_page,
429                         struct page *src_page,
430                         unsigned long extent_offset, int op)
431 {
432         pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
433         loff_t extent_base;
434         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
435         struct scatterlist src_sg, dst_sg;
436         size_t extent_size = crypt_stat->extent_size;
437         int rc;
438 
439         extent_base = (((loff_t)page_index) * (PAGE_CACHE_SIZE / extent_size));
440         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
441                                 (extent_base + extent_offset));
442         if (rc) {
443                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
444                         "extent [0x%.16llx]; rc = [%d]\n",
445                         (unsigned long long)(extent_base + extent_offset), rc);
446                 goto out;
447         }
448 
449         sg_init_table(&src_sg, 1);
450         sg_init_table(&dst_sg, 1);
451 
452         sg_set_page(&src_sg, src_page, extent_size,
453                     extent_offset * extent_size);
454         sg_set_page(&dst_sg, dst_page, extent_size,
455                     extent_offset * extent_size);
456 
457         rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
458                                extent_iv, op);
459         if (rc < 0) {
460                 printk(KERN_ERR "%s: Error attempting to crypt page with "
461                        "page_index = [%ld], extent_offset = [%ld]; "
462                        "rc = [%d]\n", __func__, page_index, extent_offset, rc);
463                 goto out;
464         }
465         rc = 0;
466 out:
467         return rc;
468 }
469 
470 /**
471  * ecryptfs_encrypt_page
472  * @page: Page mapped from the eCryptfs inode for the file; contains
473  *        decrypted content that needs to be encrypted (to a temporary
474  *        page; not in place) and written out to the lower file
475  *
476  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
477  * that eCryptfs pages may straddle the lower pages -- for instance,
478  * if the file was created on a machine with an 8K page size
479  * (resulting in an 8K header), and then the file is copied onto a
480  * host with a 32K page size, then when reading page 0 of the eCryptfs
481  * file, 24K of page 0 of the lower file will be read and decrypted,
482  * and then 8K of page 1 of the lower file will be read and decrypted.
483  *
484  * Returns zero on success; negative on error
485  */
486 int ecryptfs_encrypt_page(struct page *page)
487 {
488         struct inode *ecryptfs_inode;
489         struct ecryptfs_crypt_stat *crypt_stat;
490         char *enc_extent_virt;
491         struct page *enc_extent_page = NULL;
492         loff_t extent_offset;
493         loff_t lower_offset;
494         int rc = 0;
495 
496         ecryptfs_inode = page->mapping->host;
497         crypt_stat =
498                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
499         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
500         enc_extent_page = alloc_page(GFP_USER);
501         if (!enc_extent_page) {
502                 rc = -ENOMEM;
503                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
504                                 "encrypted extent\n");
505                 goto out;
506         }
507 
508         for (extent_offset = 0;
509              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
510              extent_offset++) {
511                 rc = crypt_extent(crypt_stat, enc_extent_page, page,
512                                   extent_offset, ENCRYPT);
513                 if (rc) {
514                         printk(KERN_ERR "%s: Error encrypting extent; "
515                                "rc = [%d]\n", __func__, rc);
516                         goto out;
517                 }
518         }
519 
520         lower_offset = lower_offset_for_page(crypt_stat, page);
521         enc_extent_virt = kmap(enc_extent_page);
522         rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
523                                   PAGE_CACHE_SIZE);
524         kunmap(enc_extent_page);
525         if (rc < 0) {
526                 ecryptfs_printk(KERN_ERR,
527                         "Error attempting to write lower page; rc = [%d]\n",
528                         rc);
529                 goto out;
530         }
531         rc = 0;
532 out:
533         if (enc_extent_page) {
534                 __free_page(enc_extent_page);
535         }
536         return rc;
537 }
538 
539 /**
540  * ecryptfs_decrypt_page
541  * @page: Page mapped from the eCryptfs inode for the file; data read
542  *        and decrypted from the lower file will be written into this
543  *        page
544  *
545  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
546  * that eCryptfs pages may straddle the lower pages -- for instance,
547  * if the file was created on a machine with an 8K page size
548  * (resulting in an 8K header), and then the file is copied onto a
549  * host with a 32K page size, then when reading page 0 of the eCryptfs
550  * file, 24K of page 0 of the lower file will be read and decrypted,
551  * and then 8K of page 1 of the lower file will be read and decrypted.
552  *
553  * Returns zero on success; negative on error
554  */
555 int ecryptfs_decrypt_page(struct page *page)
556 {
557         struct inode *ecryptfs_inode;
558         struct ecryptfs_crypt_stat *crypt_stat;
559         char *page_virt;
560         unsigned long extent_offset;
561         loff_t lower_offset;
562         int rc = 0;
563 
564         ecryptfs_inode = page->mapping->host;
565         crypt_stat =
566                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
567         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
568 
569         lower_offset = lower_offset_for_page(crypt_stat, page);
570         page_virt = kmap(page);
571         rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_CACHE_SIZE,
572                                  ecryptfs_inode);
573         kunmap(page);
574         if (rc < 0) {
575                 ecryptfs_printk(KERN_ERR,
576                         "Error attempting to read lower page; rc = [%d]\n",
577                         rc);
578                 goto out;
579         }
580 
581         for (extent_offset = 0;
582              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
583              extent_offset++) {
584                 rc = crypt_extent(crypt_stat, page, page,
585                                   extent_offset, DECRYPT);
586                 if (rc) {
587                         printk(KERN_ERR "%s: Error encrypting extent; "
588                                "rc = [%d]\n", __func__, rc);
589                         goto out;
590                 }
591         }
592 out:
593         return rc;
594 }
595 
596 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
597 
598 /**
599  * ecryptfs_init_crypt_ctx
600  * @crypt_stat: Uninitialized crypt stats structure
601  *
602  * Initialize the crypto context.
603  *
604  * TODO: Performance: Keep a cache of initialized cipher contexts;
605  * only init if needed
606  */
607 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
608 {
609         char *full_alg_name;
610         int rc = -EINVAL;
611 
612         ecryptfs_printk(KERN_DEBUG,
613                         "Initializing cipher [%s]; strlen = [%d]; "
614                         "key_size_bits = [%zd]\n",
615                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
616                         crypt_stat->key_size << 3);
617         mutex_lock(&crypt_stat->cs_tfm_mutex);
618         if (crypt_stat->tfm) {
619                 rc = 0;
620                 goto out_unlock;
621         }
622         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
623                                                     crypt_stat->cipher, "cbc");
624         if (rc)
625                 goto out_unlock;
626         crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
627         if (IS_ERR(crypt_stat->tfm)) {
628                 rc = PTR_ERR(crypt_stat->tfm);
629                 crypt_stat->tfm = NULL;
630                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
631                                 "Error initializing cipher [%s]\n",
632                                 full_alg_name);
633                 goto out_free;
634         }
635         crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
636         rc = 0;
637 out_free:
638         kfree(full_alg_name);
639 out_unlock:
640         mutex_unlock(&crypt_stat->cs_tfm_mutex);
641         return rc;
642 }
643 
644 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
645 {
646         int extent_size_tmp;
647 
648         crypt_stat->extent_mask = 0xFFFFFFFF;
649         crypt_stat->extent_shift = 0;
650         if (crypt_stat->extent_size == 0)
651                 return;
652         extent_size_tmp = crypt_stat->extent_size;
653         while ((extent_size_tmp & 0x01) == 0) {
654                 extent_size_tmp >>= 1;
655                 crypt_stat->extent_mask <<= 1;
656                 crypt_stat->extent_shift++;
657         }
658 }
659 
660 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
661 {
662         /* Default values; may be overwritten as we are parsing the
663          * packets. */
664         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
665         set_extent_mask_and_shift(crypt_stat);
666         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
667         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
668                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
669         else {
670                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
671                         crypt_stat->metadata_size =
672                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
673                 else
674                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
675         }
676 }
677 
678 /**
679  * ecryptfs_compute_root_iv
680  * @crypt_stats
681  *
682  * On error, sets the root IV to all 0's.
683  */
684 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
685 {
686         int rc = 0;
687         char dst[MD5_DIGEST_SIZE];
688 
689         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
690         BUG_ON(crypt_stat->iv_bytes <= 0);
691         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
692                 rc = -EINVAL;
693                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
694                                 "cannot generate root IV\n");
695                 goto out;
696         }
697         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
698                                     crypt_stat->key_size);
699         if (rc) {
700                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
701                                 "MD5 while generating root IV\n");
702                 goto out;
703         }
704         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
705 out:
706         if (rc) {
707                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
708                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
709         }
710         return rc;
711 }
712 
713 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
714 {
715         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
716         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
717         ecryptfs_compute_root_iv(crypt_stat);
718         if (unlikely(ecryptfs_verbosity > 0)) {
719                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
720                 ecryptfs_dump_hex(crypt_stat->key,
721                                   crypt_stat->key_size);
722         }
723 }
724 
725 /**
726  * ecryptfs_copy_mount_wide_flags_to_inode_flags
727  * @crypt_stat: The inode's cryptographic context
728  * @mount_crypt_stat: The mount point's cryptographic context
729  *
730  * This function propagates the mount-wide flags to individual inode
731  * flags.
732  */
733 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
734         struct ecryptfs_crypt_stat *crypt_stat,
735         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
736 {
737         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
738                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
739         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
740                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
741         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
742                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
743                 if (mount_crypt_stat->flags
744                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
745                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
746                 else if (mount_crypt_stat->flags
747                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
748                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
749         }
750 }
751 
752 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
753         struct ecryptfs_crypt_stat *crypt_stat,
754         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
755 {
756         struct ecryptfs_global_auth_tok *global_auth_tok;
757         int rc = 0;
758 
759         mutex_lock(&crypt_stat->keysig_list_mutex);
760         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
761 
762         list_for_each_entry(global_auth_tok,
763                             &mount_crypt_stat->global_auth_tok_list,
764                             mount_crypt_stat_list) {
765                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
766                         continue;
767                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
768                 if (rc) {
769                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
770                         goto out;
771                 }
772         }
773 
774 out:
775         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
776         mutex_unlock(&crypt_stat->keysig_list_mutex);
777         return rc;
778 }
779 
780 /**
781  * ecryptfs_set_default_crypt_stat_vals
782  * @crypt_stat: The inode's cryptographic context
783  * @mount_crypt_stat: The mount point's cryptographic context
784  *
785  * Default values in the event that policy does not override them.
786  */
787 static void ecryptfs_set_default_crypt_stat_vals(
788         struct ecryptfs_crypt_stat *crypt_stat,
789         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
790 {
791         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
792                                                       mount_crypt_stat);
793         ecryptfs_set_default_sizes(crypt_stat);
794         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
795         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
796         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
797         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
798         crypt_stat->mount_crypt_stat = mount_crypt_stat;
799 }
800 
801 /**
802  * ecryptfs_new_file_context
803  * @ecryptfs_inode: The eCryptfs inode
804  *
805  * If the crypto context for the file has not yet been established,
806  * this is where we do that.  Establishing a new crypto context
807  * involves the following decisions:
808  *  - What cipher to use?
809  *  - What set of authentication tokens to use?
810  * Here we just worry about getting enough information into the
811  * authentication tokens so that we know that they are available.
812  * We associate the available authentication tokens with the new file
813  * via the set of signatures in the crypt_stat struct.  Later, when
814  * the headers are actually written out, we may again defer to
815  * userspace to perform the encryption of the session key; for the
816  * foreseeable future, this will be the case with public key packets.
817  *
818  * Returns zero on success; non-zero otherwise
819  */
820 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
821 {
822         struct ecryptfs_crypt_stat *crypt_stat =
823             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
824         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
825             &ecryptfs_superblock_to_private(
826                     ecryptfs_inode->i_sb)->mount_crypt_stat;
827         int cipher_name_len;
828         int rc = 0;
829 
830         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
831         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
832         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
833                                                       mount_crypt_stat);
834         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
835                                                          mount_crypt_stat);
836         if (rc) {
837                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
838                        "to the inode key sigs; rc = [%d]\n", rc);
839                 goto out;
840         }
841         cipher_name_len =
842                 strlen(mount_crypt_stat->global_default_cipher_name);
843         memcpy(crypt_stat->cipher,
844                mount_crypt_stat->global_default_cipher_name,
845                cipher_name_len);
846         crypt_stat->cipher[cipher_name_len] = '\0';
847         crypt_stat->key_size =
848                 mount_crypt_stat->global_default_cipher_key_size;
849         ecryptfs_generate_new_key(crypt_stat);
850         rc = ecryptfs_init_crypt_ctx(crypt_stat);
851         if (rc)
852                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
853                                 "context for cipher [%s]: rc = [%d]\n",
854                                 crypt_stat->cipher, rc);
855 out:
856         return rc;
857 }
858 
859 /**
860  * ecryptfs_validate_marker - check for the ecryptfs marker
861  * @data: The data block in which to check
862  *
863  * Returns zero if marker found; -EINVAL if not found
864  */
865 static int ecryptfs_validate_marker(char *data)
866 {
867         u32 m_1, m_2;
868 
869         m_1 = get_unaligned_be32(data);
870         m_2 = get_unaligned_be32(data + 4);
871         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
872                 return 0;
873         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
874                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
875                         MAGIC_ECRYPTFS_MARKER);
876         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
877                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
878         return -EINVAL;
879 }
880 
881 struct ecryptfs_flag_map_elem {
882         u32 file_flag;
883         u32 local_flag;
884 };
885 
886 /* Add support for additional flags by adding elements here. */
887 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
888         {0x00000001, ECRYPTFS_ENABLE_HMAC},
889         {0x00000002, ECRYPTFS_ENCRYPTED},
890         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
891         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
892 };
893 
894 /**
895  * ecryptfs_process_flags
896  * @crypt_stat: The cryptographic context
897  * @page_virt: Source data to be parsed
898  * @bytes_read: Updated with the number of bytes read
899  *
900  * Returns zero on success; non-zero if the flag set is invalid
901  */
902 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
903                                   char *page_virt, int *bytes_read)
904 {
905         int rc = 0;
906         int i;
907         u32 flags;
908 
909         flags = get_unaligned_be32(page_virt);
910         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
911                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
912                 if (flags & ecryptfs_flag_map[i].file_flag) {
913                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
914                 } else
915                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
916         /* Version is in top 8 bits of the 32-bit flag vector */
917         crypt_stat->file_version = ((flags >> 24) & 0xFF);
918         (*bytes_read) = 4;
919         return rc;
920 }
921 
922 /**
923  * write_ecryptfs_marker
924  * @page_virt: The pointer to in a page to begin writing the marker
925  * @written: Number of bytes written
926  *
927  * Marker = 0x3c81b7f5
928  */
929 static void write_ecryptfs_marker(char *page_virt, size_t *written)
930 {
931         u32 m_1, m_2;
932 
933         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
934         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
935         put_unaligned_be32(m_1, page_virt);
936         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
937         put_unaligned_be32(m_2, page_virt);
938         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
939 }
940 
941 void ecryptfs_write_crypt_stat_flags(char *page_virt,
942                                      struct ecryptfs_crypt_stat *crypt_stat,
943                                      size_t *written)
944 {
945         u32 flags = 0;
946         int i;
947 
948         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
949                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
950                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
951                         flags |= ecryptfs_flag_map[i].file_flag;
952         /* Version is in top 8 bits of the 32-bit flag vector */
953         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
954         put_unaligned_be32(flags, page_virt);
955         (*written) = 4;
956 }
957 
958 struct ecryptfs_cipher_code_str_map_elem {
959         char cipher_str[16];
960         u8 cipher_code;
961 };
962 
963 /* Add support for additional ciphers by adding elements here. The
964  * cipher_code is whatever OpenPGP applicatoins use to identify the
965  * ciphers. List in order of probability. */
966 static struct ecryptfs_cipher_code_str_map_elem
967 ecryptfs_cipher_code_str_map[] = {
968         {"aes",RFC2440_CIPHER_AES_128 },
969         {"blowfish", RFC2440_CIPHER_BLOWFISH},
970         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
971         {"cast5", RFC2440_CIPHER_CAST_5},
972         {"twofish", RFC2440_CIPHER_TWOFISH},
973         {"cast6", RFC2440_CIPHER_CAST_6},
974         {"aes", RFC2440_CIPHER_AES_192},
975         {"aes", RFC2440_CIPHER_AES_256}
976 };
977 
978 /**
979  * ecryptfs_code_for_cipher_string
980  * @cipher_name: The string alias for the cipher
981  * @key_bytes: Length of key in bytes; used for AES code selection
982  *
983  * Returns zero on no match, or the cipher code on match
984  */
985 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
986 {
987         int i;
988         u8 code = 0;
989         struct ecryptfs_cipher_code_str_map_elem *map =
990                 ecryptfs_cipher_code_str_map;
991 
992         if (strcmp(cipher_name, "aes") == 0) {
993                 switch (key_bytes) {
994                 case 16:
995                         code = RFC2440_CIPHER_AES_128;
996                         break;
997                 case 24:
998                         code = RFC2440_CIPHER_AES_192;
999                         break;
1000                 case 32:
1001                         code = RFC2440_CIPHER_AES_256;
1002                 }
1003         } else {
1004                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1005                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1006                                 code = map[i].cipher_code;
1007                                 break;
1008                         }
1009         }
1010         return code;
1011 }
1012 
1013 /**
1014  * ecryptfs_cipher_code_to_string
1015  * @str: Destination to write out the cipher name
1016  * @cipher_code: The code to convert to cipher name string
1017  *
1018  * Returns zero on success
1019  */
1020 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1021 {
1022         int rc = 0;
1023         int i;
1024 
1025         str[0] = '\0';
1026         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1027                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1028                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1029         if (str[0] == '\0') {
1030                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1031                                 "[%d]\n", cipher_code);
1032                 rc = -EINVAL;
1033         }
1034         return rc;
1035 }
1036 
1037 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1038 {
1039         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1040         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1041         int rc;
1042 
1043         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1044                                  inode);
1045         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1046                 return rc >= 0 ? -EINVAL : rc;
1047         rc = ecryptfs_validate_marker(marker);
1048         if (!rc)
1049                 ecryptfs_i_size_init(file_size, inode);
1050         return rc;
1051 }
1052 
1053 void
1054 ecryptfs_write_header_metadata(char *virt,
1055                                struct ecryptfs_crypt_stat *crypt_stat,
1056                                size_t *written)
1057 {
1058         u32 header_extent_size;
1059         u16 num_header_extents_at_front;
1060 
1061         header_extent_size = (u32)crypt_stat->extent_size;
1062         num_header_extents_at_front =
1063                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1064         put_unaligned_be32(header_extent_size, virt);
1065         virt += 4;
1066         put_unaligned_be16(num_header_extents_at_front, virt);
1067         (*written) = 6;
1068 }
1069 
1070 struct kmem_cache *ecryptfs_header_cache;
1071 
1072 /**
1073  * ecryptfs_write_headers_virt
1074  * @page_virt: The virtual address to write the headers to
1075  * @max: The size of memory allocated at page_virt
1076  * @size: Set to the number of bytes written by this function
1077  * @crypt_stat: The cryptographic context
1078  * @ecryptfs_dentry: The eCryptfs dentry
1079  *
1080  * Format version: 1
1081  *
1082  *   Header Extent:
1083  *     Octets 0-7:        Unencrypted file size (big-endian)
1084  *     Octets 8-15:       eCryptfs special marker
1085  *     Octets 16-19:      Flags
1086  *      Octet 16:         File format version number (between 0 and 255)
1087  *      Octets 17-18:     Reserved
1088  *      Octet 19:         Bit 1 (lsb): Reserved
1089  *                        Bit 2: Encrypted?
1090  *                        Bits 3-8: Reserved
1091  *     Octets 20-23:      Header extent size (big-endian)
1092  *     Octets 24-25:      Number of header extents at front of file
1093  *                        (big-endian)
1094  *     Octet  26:         Begin RFC 2440 authentication token packet set
1095  *   Data Extent 0:
1096  *     Lower data (CBC encrypted)
1097  *   Data Extent 1:
1098  *     Lower data (CBC encrypted)
1099  *   ...
1100  *
1101  * Returns zero on success
1102  */
1103 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1104                                        size_t *size,
1105                                        struct ecryptfs_crypt_stat *crypt_stat,
1106                                        struct dentry *ecryptfs_dentry)
1107 {
1108         int rc;
1109         size_t written;
1110         size_t offset;
1111 
1112         offset = ECRYPTFS_FILE_SIZE_BYTES;
1113         write_ecryptfs_marker((page_virt + offset), &written);
1114         offset += written;
1115         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1116                                         &written);
1117         offset += written;
1118         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1119                                        &written);
1120         offset += written;
1121         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1122                                               ecryptfs_dentry, &written,
1123                                               max - offset);
1124         if (rc)
1125                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1126                                 "set; rc = [%d]\n", rc);
1127         if (size) {
1128                 offset += written;
1129                 *size = offset;
1130         }
1131         return rc;
1132 }
1133 
1134 static int
1135 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1136                                     char *virt, size_t virt_len)
1137 {
1138         int rc;
1139 
1140         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1141                                   0, virt_len);
1142         if (rc < 0)
1143                 printk(KERN_ERR "%s: Error attempting to write header "
1144                        "information to lower file; rc = [%d]\n", __func__, rc);
1145         else
1146                 rc = 0;
1147         return rc;
1148 }
1149 
1150 static int
1151 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1152                                  char *page_virt, size_t size)
1153 {
1154         int rc;
1155 
1156         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1157                                size, 0);
1158         return rc;
1159 }
1160 
1161 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1162                                                unsigned int order)
1163 {
1164         struct page *page;
1165 
1166         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1167         if (page)
1168                 return (unsigned long) page_address(page);
1169         return 0;
1170 }
1171 
1172 /**
1173  * ecryptfs_write_metadata
1174  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1175  * @ecryptfs_inode: The newly created eCryptfs inode
1176  *
1177  * Write the file headers out.  This will likely involve a userspace
1178  * callout, in which the session key is encrypted with one or more
1179  * public keys and/or the passphrase necessary to do the encryption is
1180  * retrieved via a prompt.  Exactly what happens at this point should
1181  * be policy-dependent.
1182  *
1183  * Returns zero on success; non-zero on error
1184  */
1185 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1186                             struct inode *ecryptfs_inode)
1187 {
1188         struct ecryptfs_crypt_stat *crypt_stat =
1189                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1190         unsigned int order;
1191         char *virt;
1192         size_t virt_len;
1193         size_t size = 0;
1194         int rc = 0;
1195 
1196         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1197                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1198                         printk(KERN_ERR "Key is invalid; bailing out\n");
1199                         rc = -EINVAL;
1200                         goto out;
1201                 }
1202         } else {
1203                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1204                        __func__);
1205                 rc = -EINVAL;
1206                 goto out;
1207         }
1208         virt_len = crypt_stat->metadata_size;
1209         order = get_order(virt_len);
1210         /* Released in this function */
1211         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1212         if (!virt) {
1213                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1214                 rc = -ENOMEM;
1215                 goto out;
1216         }
1217         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1218         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1219                                          ecryptfs_dentry);
1220         if (unlikely(rc)) {
1221                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1222                        __func__, rc);
1223                 goto out_free;
1224         }
1225         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1226                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1227                                                       size);
1228         else
1229                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1230                                                          virt_len);
1231         if (rc) {
1232                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1233                        "rc = [%d]\n", __func__, rc);
1234                 goto out_free;
1235         }
1236 out_free:
1237         free_pages((unsigned long)virt, order);
1238 out:
1239         return rc;
1240 }
1241 
1242 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1243 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1244 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1245                                  char *virt, int *bytes_read,
1246                                  int validate_header_size)
1247 {
1248         int rc = 0;
1249         u32 header_extent_size;
1250         u16 num_header_extents_at_front;
1251 
1252         header_extent_size = get_unaligned_be32(virt);
1253         virt += sizeof(__be32);
1254         num_header_extents_at_front = get_unaligned_be16(virt);
1255         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1256                                      * (size_t)header_extent_size));
1257         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1258         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1259             && (crypt_stat->metadata_size
1260                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1261                 rc = -EINVAL;
1262                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1263                        crypt_stat->metadata_size);
1264         }
1265         return rc;
1266 }
1267 
1268 /**
1269  * set_default_header_data
1270  * @crypt_stat: The cryptographic context
1271  *
1272  * For version 0 file format; this function is only for backwards
1273  * compatibility for files created with the prior versions of
1274  * eCryptfs.
1275  */
1276 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1277 {
1278         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1279 }
1280 
1281 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1282 {
1283         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1284         struct ecryptfs_crypt_stat *crypt_stat;
1285         u64 file_size;
1286 
1287         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1288         mount_crypt_stat =
1289                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1290         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1291                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1292                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1293                         file_size += crypt_stat->metadata_size;
1294         } else
1295                 file_size = get_unaligned_be64(page_virt);
1296         i_size_write(inode, (loff_t)file_size);
1297         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1298 }
1299 
1300 /**
1301  * ecryptfs_read_headers_virt
1302  * @page_virt: The virtual address into which to read the headers
1303  * @crypt_stat: The cryptographic context
1304  * @ecryptfs_dentry: The eCryptfs dentry
1305  * @validate_header_size: Whether to validate the header size while reading
1306  *
1307  * Read/parse the header data. The header format is detailed in the
1308  * comment block for the ecryptfs_write_headers_virt() function.
1309  *
1310  * Returns zero on success
1311  */
1312 static int ecryptfs_read_headers_virt(char *page_virt,
1313                                       struct ecryptfs_crypt_stat *crypt_stat,
1314                                       struct dentry *ecryptfs_dentry,
1315                                       int validate_header_size)
1316 {
1317         int rc = 0;
1318         int offset;
1319         int bytes_read;
1320 
1321         ecryptfs_set_default_sizes(crypt_stat);
1322         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1323                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1324         offset = ECRYPTFS_FILE_SIZE_BYTES;
1325         rc = ecryptfs_validate_marker(page_virt + offset);
1326         if (rc)
1327                 goto out;
1328         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1329                 ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1330         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1331         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1332                                     &bytes_read);
1333         if (rc) {
1334                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1335                 goto out;
1336         }
1337         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1338                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1339                                 "file version [%d] is supported by this "
1340                                 "version of eCryptfs\n",
1341                                 crypt_stat->file_version,
1342                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1343                 rc = -EINVAL;
1344                 goto out;
1345         }
1346         offset += bytes_read;
1347         if (crypt_stat->file_version >= 1) {
1348                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1349                                            &bytes_read, validate_header_size);
1350                 if (rc) {
1351                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1352                                         "metadata; rc = [%d]\n", rc);
1353                 }
1354                 offset += bytes_read;
1355         } else
1356                 set_default_header_data(crypt_stat);
1357         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1358                                        ecryptfs_dentry);
1359 out:
1360         return rc;
1361 }
1362 
1363 /**
1364  * ecryptfs_read_xattr_region
1365  * @page_virt: The vitual address into which to read the xattr data
1366  * @ecryptfs_inode: The eCryptfs inode
1367  *
1368  * Attempts to read the crypto metadata from the extended attribute
1369  * region of the lower file.
1370  *
1371  * Returns zero on success; non-zero on error
1372  */
1373 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1374 {
1375         struct dentry *lower_dentry =
1376                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1377         ssize_t size;
1378         int rc = 0;
1379 
1380         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1381                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1382         if (size < 0) {
1383                 if (unlikely(ecryptfs_verbosity > 0))
1384                         printk(KERN_INFO "Error attempting to read the [%s] "
1385                                "xattr from the lower file; return value = "
1386                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1387                 rc = -EINVAL;
1388                 goto out;
1389         }
1390 out:
1391         return rc;
1392 }
1393 
1394 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1395                                             struct inode *inode)
1396 {
1397         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1398         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1399         int rc;
1400 
1401         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1402                                      ECRYPTFS_XATTR_NAME, file_size,
1403                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1404         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1405                 return rc >= 0 ? -EINVAL : rc;
1406         rc = ecryptfs_validate_marker(marker);
1407         if (!rc)
1408                 ecryptfs_i_size_init(file_size, inode);
1409         return rc;
1410 }
1411 
1412 /**
1413  * ecryptfs_read_metadata
1414  *
1415  * Common entry point for reading file metadata. From here, we could
1416  * retrieve the header information from the header region of the file,
1417  * the xattr region of the file, or some other repostory that is
1418  * stored separately from the file itself. The current implementation
1419  * supports retrieving the metadata information from the file contents
1420  * and from the xattr region.
1421  *
1422  * Returns zero if valid headers found and parsed; non-zero otherwise
1423  */
1424 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1425 {
1426         int rc;
1427         char *page_virt;
1428         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1429         struct ecryptfs_crypt_stat *crypt_stat =
1430             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1431         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1432                 &ecryptfs_superblock_to_private(
1433                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1434 
1435         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1436                                                       mount_crypt_stat);
1437         /* Read the first page from the underlying file */
1438         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1439         if (!page_virt) {
1440                 rc = -ENOMEM;
1441                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1442                        __func__);
1443                 goto out;
1444         }
1445         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1446                                  ecryptfs_inode);
1447         if (rc >= 0)
1448                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1449                                                 ecryptfs_dentry,
1450                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1451         if (rc) {
1452                 /* metadata is not in the file header, so try xattrs */
1453                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1454                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1455                 if (rc) {
1456                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1457                                "file header region or xattr region, inode %lu\n",
1458                                 ecryptfs_inode->i_ino);
1459                         rc = -EINVAL;
1460                         goto out;
1461                 }
1462                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1463                                                 ecryptfs_dentry,
1464                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1465                 if (rc) {
1466                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1467                                "file xattr region either, inode %lu\n",
1468                                 ecryptfs_inode->i_ino);
1469                         rc = -EINVAL;
1470                 }
1471                 if (crypt_stat->mount_crypt_stat->flags
1472                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1473                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1474                 } else {
1475                         printk(KERN_WARNING "Attempt to access file with "
1476                                "crypto metadata only in the extended attribute "
1477                                "region, but eCryptfs was mounted without "
1478                                "xattr support enabled. eCryptfs will not treat "
1479                                "this like an encrypted file, inode %lu\n",
1480                                 ecryptfs_inode->i_ino);
1481                         rc = -EINVAL;
1482                 }
1483         }
1484 out:
1485         if (page_virt) {
1486                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1487                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1488         }
1489         return rc;
1490 }
1491 
1492 /**
1493  * ecryptfs_encrypt_filename - encrypt filename
1494  *
1495  * CBC-encrypts the filename. We do not want to encrypt the same
1496  * filename with the same key and IV, which may happen with hard
1497  * links, so we prepend random bits to each filename.
1498  *
1499  * Returns zero on success; non-zero otherwise
1500  */
1501 static int
1502 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1503                           struct ecryptfs_crypt_stat *crypt_stat,
1504                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1505 {
1506         int rc = 0;
1507 
1508         filename->encrypted_filename = NULL;
1509         filename->encrypted_filename_size = 0;
1510         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1511             || (mount_crypt_stat && (mount_crypt_stat->flags
1512                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1513                 size_t packet_size;
1514                 size_t remaining_bytes;
1515 
1516                 rc = ecryptfs_write_tag_70_packet(
1517                         NULL, NULL,
1518                         &filename->encrypted_filename_size,
1519                         mount_crypt_stat, NULL,
1520                         filename->filename_size);
1521                 if (rc) {
1522                         printk(KERN_ERR "%s: Error attempting to get packet "
1523                                "size for tag 72; rc = [%d]\n", __func__,
1524                                rc);
1525                         filename->encrypted_filename_size = 0;
1526                         goto out;
1527                 }
1528                 filename->encrypted_filename =
1529                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1530                 if (!filename->encrypted_filename) {
1531                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1532                                "to kmalloc [%zd] bytes\n", __func__,
1533                                filename->encrypted_filename_size);
1534                         rc = -ENOMEM;
1535                         goto out;
1536                 }
1537                 remaining_bytes = filename->encrypted_filename_size;
1538                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1539                                                   &remaining_bytes,
1540                                                   &packet_size,
1541                                                   mount_crypt_stat,
1542                                                   filename->filename,
1543                                                   filename->filename_size);
1544                 if (rc) {
1545                         printk(KERN_ERR "%s: Error attempting to generate "
1546                                "tag 70 packet; rc = [%d]\n", __func__,
1547                                rc);
1548                         kfree(filename->encrypted_filename);
1549                         filename->encrypted_filename = NULL;
1550                         filename->encrypted_filename_size = 0;
1551                         goto out;
1552                 }
1553                 filename->encrypted_filename_size = packet_size;
1554         } else {
1555                 printk(KERN_ERR "%s: No support for requested filename "
1556                        "encryption method in this release\n", __func__);
1557                 rc = -EOPNOTSUPP;
1558                 goto out;
1559         }
1560 out:
1561         return rc;
1562 }
1563 
1564 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1565                                   const char *name, size_t name_size)
1566 {
1567         int rc = 0;
1568 
1569         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1570         if (!(*copied_name)) {
1571                 rc = -ENOMEM;
1572                 goto out;
1573         }
1574         memcpy((void *)(*copied_name), (void *)name, name_size);
1575         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1576                                                  * in printing out the
1577                                                  * string in debug
1578                                                  * messages */
1579         (*copied_name_size) = name_size;
1580 out:
1581         return rc;
1582 }
1583 
1584 /**
1585  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1586  * @key_tfm: Crypto context for key material, set by this function
1587  * @cipher_name: Name of the cipher
1588  * @key_size: Size of the key in bytes
1589  *
1590  * Returns zero on success. Any crypto_tfm structs allocated here
1591  * should be released by other functions, such as on a superblock put
1592  * event, regardless of whether this function succeeds for fails.
1593  */
1594 static int
1595 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1596                             char *cipher_name, size_t *key_size)
1597 {
1598         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1599         char *full_alg_name = NULL;
1600         int rc;
1601 
1602         *key_tfm = NULL;
1603         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1604                 rc = -EINVAL;
1605                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1606                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1607                 goto out;
1608         }
1609         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1610                                                     "ecb");
1611         if (rc)
1612                 goto out;
1613         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1614         if (IS_ERR(*key_tfm)) {
1615                 rc = PTR_ERR(*key_tfm);
1616                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1617                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1618                 goto out;
1619         }
1620         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1621         if (*key_size == 0) {
1622                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1623 
1624                 *key_size = alg->max_keysize;
1625         }
1626         get_random_bytes(dummy_key, *key_size);
1627         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1628         if (rc) {
1629                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1630                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1631                        rc);
1632                 rc = -EINVAL;
1633                 goto out;
1634         }
1635 out:
1636         kfree(full_alg_name);
1637         return rc;
1638 }
1639 
1640 struct kmem_cache *ecryptfs_key_tfm_cache;
1641 static struct list_head key_tfm_list;
1642 struct mutex key_tfm_list_mutex;
1643 
1644 int __init ecryptfs_init_crypto(void)
1645 {
1646         mutex_init(&key_tfm_list_mutex);
1647         INIT_LIST_HEAD(&key_tfm_list);
1648         return 0;
1649 }
1650 
1651 /**
1652  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1653  *
1654  * Called only at module unload time
1655  */
1656 int ecryptfs_destroy_crypto(void)
1657 {
1658         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1659 
1660         mutex_lock(&key_tfm_list_mutex);
1661         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1662                                  key_tfm_list) {
1663                 list_del(&key_tfm->key_tfm_list);
1664                 if (key_tfm->key_tfm)
1665                         crypto_free_blkcipher(key_tfm->key_tfm);
1666                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1667         }
1668         mutex_unlock(&key_tfm_list_mutex);
1669         return 0;
1670 }
1671 
1672 int
1673 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1674                          size_t key_size)
1675 {
1676         struct ecryptfs_key_tfm *tmp_tfm;
1677         int rc = 0;
1678 
1679         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1680 
1681         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1682         if (key_tfm != NULL)
1683                 (*key_tfm) = tmp_tfm;
1684         if (!tmp_tfm) {
1685                 rc = -ENOMEM;
1686                 printk(KERN_ERR "Error attempting to allocate from "
1687                        "ecryptfs_key_tfm_cache\n");
1688                 goto out;
1689         }
1690         mutex_init(&tmp_tfm->key_tfm_mutex);
1691         strncpy(tmp_tfm->cipher_name, cipher_name,
1692                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1693         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1694         tmp_tfm->key_size = key_size;
1695         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1696                                          tmp_tfm->cipher_name,
1697                                          &tmp_tfm->key_size);
1698         if (rc) {
1699                 printk(KERN_ERR "Error attempting to initialize key TFM "
1700                        "cipher with name = [%s]; rc = [%d]\n",
1701                        tmp_tfm->cipher_name, rc);
1702                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1703                 if (key_tfm != NULL)
1704                         (*key_tfm) = NULL;
1705                 goto out;
1706         }
1707         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1708 out:
1709         return rc;
1710 }
1711 
1712 /**
1713  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1714  * @cipher_name: the name of the cipher to search for
1715  * @key_tfm: set to corresponding tfm if found
1716  *
1717  * Searches for cached key_tfm matching @cipher_name
1718  * Must be called with &key_tfm_list_mutex held
1719  * Returns 1 if found, with @key_tfm set
1720  * Returns 0 if not found, with @key_tfm set to NULL
1721  */
1722 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1723 {
1724         struct ecryptfs_key_tfm *tmp_key_tfm;
1725 
1726         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1727 
1728         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1729                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1730                         if (key_tfm)
1731                                 (*key_tfm) = tmp_key_tfm;
1732                         return 1;
1733                 }
1734         }
1735         if (key_tfm)
1736                 (*key_tfm) = NULL;
1737         return 0;
1738 }
1739 
1740 /**
1741  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1742  *
1743  * @tfm: set to cached tfm found, or new tfm created
1744  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1745  * @cipher_name: the name of the cipher to search for and/or add
1746  *
1747  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1748  * Searches for cached item first, and creates new if not found.
1749  * Returns 0 on success, non-zero if adding new cipher failed
1750  */
1751 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1752                                                struct mutex **tfm_mutex,
1753                                                char *cipher_name)
1754 {
1755         struct ecryptfs_key_tfm *key_tfm;
1756         int rc = 0;
1757 
1758         (*tfm) = NULL;
1759         (*tfm_mutex) = NULL;
1760 
1761         mutex_lock(&key_tfm_list_mutex);
1762         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1763                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1764                 if (rc) {
1765                         printk(KERN_ERR "Error adding new key_tfm to list; "
1766                                         "rc = [%d]\n", rc);
1767                         goto out;
1768                 }
1769         }
1770         (*tfm) = key_tfm->key_tfm;
1771         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1772 out:
1773         mutex_unlock(&key_tfm_list_mutex);
1774         return rc;
1775 }
1776 
1777 /* 64 characters forming a 6-bit target field */
1778 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1779                                                  "EFGHIJKLMNOPQRST"
1780                                                  "UVWXYZabcdefghij"
1781                                                  "klmnopqrstuvwxyz");
1782 
1783 /* We could either offset on every reverse map or just pad some 0x00's
1784  * at the front here */
1785 static const unsigned char filename_rev_map[256] = {
1786         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1787         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1788         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1789         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1790         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1791         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1792         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1793         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1794         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1795         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1796         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1797         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1798         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1799         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1800         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1801         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1802 };
1803 
1804 /**
1805  * ecryptfs_encode_for_filename
1806  * @dst: Destination location for encoded filename
1807  * @dst_size: Size of the encoded filename in bytes
1808  * @src: Source location for the filename to encode
1809  * @src_size: Size of the source in bytes
1810  */
1811 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1812                                   unsigned char *src, size_t src_size)
1813 {
1814         size_t num_blocks;
1815         size_t block_num = 0;
1816         size_t dst_offset = 0;
1817         unsigned char last_block[3];
1818 
1819         if (src_size == 0) {
1820                 (*dst_size) = 0;
1821                 goto out;
1822         }
1823         num_blocks = (src_size / 3);
1824         if ((src_size % 3) == 0) {
1825                 memcpy(last_block, (&src[src_size - 3]), 3);
1826         } else {
1827                 num_blocks++;
1828                 last_block[2] = 0x00;
1829                 switch (src_size % 3) {
1830                 case 1:
1831                         last_block[0] = src[src_size - 1];
1832                         last_block[1] = 0x00;
1833                         break;
1834                 case 2:
1835                         last_block[0] = src[src_size - 2];
1836                         last_block[1] = src[src_size - 1];
1837                 }
1838         }
1839         (*dst_size) = (num_blocks * 4);
1840         if (!dst)
1841                 goto out;
1842         while (block_num < num_blocks) {
1843                 unsigned char *src_block;
1844                 unsigned char dst_block[4];
1845 
1846                 if (block_num == (num_blocks - 1))
1847                         src_block = last_block;
1848                 else
1849                         src_block = &src[block_num * 3];
1850                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1851                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1852                                 | ((src_block[1] >> 4) & 0x0F));
1853                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1854                                 | ((src_block[2] >> 6) & 0x03));
1855                 dst_block[3] = (src_block[2] & 0x3F);
1856                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1857                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1858                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1859                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1860                 block_num++;
1861         }
1862 out:
1863         return;
1864 }
1865 
1866 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1867 {
1868         /* Not exact; conservatively long. Every block of 4
1869          * encoded characters decodes into a block of 3
1870          * decoded characters. This segment of code provides
1871          * the caller with the maximum amount of allocated
1872          * space that @dst will need to point to in a
1873          * subsequent call. */
1874         return ((encoded_size + 1) * 3) / 4;
1875 }
1876 
1877 /**
1878  * ecryptfs_decode_from_filename
1879  * @dst: If NULL, this function only sets @dst_size and returns. If
1880  *       non-NULL, this function decodes the encoded octets in @src
1881  *       into the memory that @dst points to.
1882  * @dst_size: Set to the size of the decoded string.
1883  * @src: The encoded set of octets to decode.
1884  * @src_size: The size of the encoded set of octets to decode.
1885  */
1886 static void
1887 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1888                               const unsigned char *src, size_t src_size)
1889 {
1890         u8 current_bit_offset = 0;
1891         size_t src_byte_offset = 0;
1892         size_t dst_byte_offset = 0;
1893 
1894         if (dst == NULL) {
1895                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1896                 goto out;
1897         }
1898         while (src_byte_offset < src_size) {
1899                 unsigned char src_byte =
1900                                 filename_rev_map[(int)src[src_byte_offset]];
1901 
1902                 switch (current_bit_offset) {
1903                 case 0:
1904                         dst[dst_byte_offset] = (src_byte << 2);
1905                         current_bit_offset = 6;
1906                         break;
1907                 case 6:
1908                         dst[dst_byte_offset++] |= (src_byte >> 4);
1909                         dst[dst_byte_offset] = ((src_byte & 0xF)
1910                                                  << 4);
1911                         current_bit_offset = 4;
1912                         break;
1913                 case 4:
1914                         dst[dst_byte_offset++] |= (src_byte >> 2);
1915                         dst[dst_byte_offset] = (src_byte << 6);
1916                         current_bit_offset = 2;
1917                         break;
1918                 case 2:
1919                         dst[dst_byte_offset++] |= (src_byte);
1920                         current_bit_offset = 0;
1921                         break;
1922                 }
1923                 src_byte_offset++;
1924         }
1925         (*dst_size) = dst_byte_offset;
1926 out:
1927         return;
1928 }
1929 
1930 /**
1931  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1932  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1933  * @name: The plaintext name
1934  * @length: The length of the plaintext
1935  * @encoded_name: The encypted name
1936  *
1937  * Encrypts and encodes a filename into something that constitutes a
1938  * valid filename for a filesystem, with printable characters.
1939  *
1940  * We assume that we have a properly initialized crypto context,
1941  * pointed to by crypt_stat->tfm.
1942  *
1943  * Returns zero on success; non-zero on otherwise
1944  */
1945 int ecryptfs_encrypt_and_encode_filename(
1946         char **encoded_name,
1947         size_t *encoded_name_size,
1948         struct ecryptfs_crypt_stat *crypt_stat,
1949         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1950         const char *name, size_t name_size)
1951 {
1952         size_t encoded_name_no_prefix_size;
1953         int rc = 0;
1954 
1955         (*encoded_name) = NULL;
1956         (*encoded_name_size) = 0;
1957         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
1958             || (mount_crypt_stat && (mount_crypt_stat->flags
1959                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
1960                 struct ecryptfs_filename *filename;
1961 
1962                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1963                 if (!filename) {
1964                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1965                                "to kzalloc [%zd] bytes\n", __func__,
1966                                sizeof(*filename));
1967                         rc = -ENOMEM;
1968                         goto out;
1969                 }
1970                 filename->filename = (char *)name;
1971                 filename->filename_size = name_size;
1972                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
1973                                                mount_crypt_stat);
1974                 if (rc) {
1975                         printk(KERN_ERR "%s: Error attempting to encrypt "
1976                                "filename; rc = [%d]\n", __func__, rc);
1977                         kfree(filename);
1978                         goto out;
1979                 }
1980                 ecryptfs_encode_for_filename(
1981                         NULL, &encoded_name_no_prefix_size,
1982                         filename->encrypted_filename,
1983                         filename->encrypted_filename_size);
1984                 if ((crypt_stat && (crypt_stat->flags
1985                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1986                     || (mount_crypt_stat
1987                         && (mount_crypt_stat->flags
1988                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
1989                         (*encoded_name_size) =
1990                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1991                                  + encoded_name_no_prefix_size);
1992                 else
1993                         (*encoded_name_size) =
1994                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1995                                  + encoded_name_no_prefix_size);
1996                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1997                 if (!(*encoded_name)) {
1998                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1999                                "to kzalloc [%zd] bytes\n", __func__,
2000                                (*encoded_name_size));
2001                         rc = -ENOMEM;
2002                         kfree(filename->encrypted_filename);
2003                         kfree(filename);
2004                         goto out;
2005                 }
2006                 if ((crypt_stat && (crypt_stat->flags
2007                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2008                     || (mount_crypt_stat
2009                         && (mount_crypt_stat->flags
2010                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2011                         memcpy((*encoded_name),
2012                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2013                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2014                         ecryptfs_encode_for_filename(
2015                             ((*encoded_name)
2016                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2017                             &encoded_name_no_prefix_size,
2018                             filename->encrypted_filename,
2019                             filename->encrypted_filename_size);
2020                         (*encoded_name_size) =
2021                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2022                                  + encoded_name_no_prefix_size);
2023                         (*encoded_name)[(*encoded_name_size)] = '\0';
2024                 } else {
2025                         rc = -EOPNOTSUPP;
2026                 }
2027                 if (rc) {
2028                         printk(KERN_ERR "%s: Error attempting to encode "
2029                                "encrypted filename; rc = [%d]\n", __func__,
2030                                rc);
2031                         kfree((*encoded_name));
2032                         (*encoded_name) = NULL;
2033                         (*encoded_name_size) = 0;
2034                 }
2035                 kfree(filename->encrypted_filename);
2036                 kfree(filename);
2037         } else {
2038                 rc = ecryptfs_copy_filename(encoded_name,
2039                                             encoded_name_size,
2040                                             name, name_size);
2041         }
2042 out:
2043         return rc;
2044 }
2045 
2046 /**
2047  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2048  * @plaintext_name: The plaintext name
2049  * @plaintext_name_size: The plaintext name size
2050  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2051  * @name: The filename in cipher text
2052  * @name_size: The cipher text name size
2053  *
2054  * Decrypts and decodes the filename.
2055  *
2056  * Returns zero on error; non-zero otherwise
2057  */
2058 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2059                                          size_t *plaintext_name_size,
2060                                          struct super_block *sb,
2061                                          const char *name, size_t name_size)
2062 {
2063         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2064                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2065         char *decoded_name;
2066         size_t decoded_name_size;
2067         size_t packet_size;
2068         int rc = 0;
2069 
2070         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2071             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2072             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2073             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2074                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2075                 const char *orig_name = name;
2076                 size_t orig_name_size = name_size;
2077 
2078                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2079                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2080                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2081                                               name, name_size);
2082                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2083                 if (!decoded_name) {
2084                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2085                                "to kmalloc [%zd] bytes\n", __func__,
2086                                decoded_name_size);
2087                         rc = -ENOMEM;
2088                         goto out;
2089                 }
2090                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2091                                               name, name_size);
2092                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2093                                                   plaintext_name_size,
2094                                                   &packet_size,
2095                                                   mount_crypt_stat,
2096                                                   decoded_name,
2097                                                   decoded_name_size);
2098                 if (rc) {
2099                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2100                                "from filename; copying through filename "
2101                                "as-is\n", __func__);
2102                         rc = ecryptfs_copy_filename(plaintext_name,
2103                                                     plaintext_name_size,
2104                                                     orig_name, orig_name_size);
2105                         goto out_free;
2106                 }
2107         } else {
2108                 rc = ecryptfs_copy_filename(plaintext_name,
2109                                             plaintext_name_size,
2110                                             name, name_size);
2111                 goto out;
2112         }
2113 out_free:
2114         kfree(decoded_name);
2115 out:
2116         return rc;
2117 }
2118 
2119 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2120 
2121 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2122                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2123 {
2124         struct blkcipher_desc desc;
2125         struct mutex *tfm_mutex;
2126         size_t cipher_blocksize;
2127         int rc;
2128 
2129         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2130                 (*namelen) = lower_namelen;
2131                 return 0;
2132         }
2133 
2134         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2135                         mount_crypt_stat->global_default_fn_cipher_name);
2136         if (unlikely(rc)) {
2137                 (*namelen) = 0;
2138                 return rc;
2139         }
2140 
2141         mutex_lock(tfm_mutex);
2142         cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2143         mutex_unlock(tfm_mutex);
2144 
2145         /* Return an exact amount for the common cases */
2146         if (lower_namelen == NAME_MAX
2147             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2148                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2149                 return 0;
2150         }
2151 
2152         /* Return a safe estimate for the uncommon cases */
2153         (*namelen) = lower_namelen;
2154         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2155         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2156         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2157         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2158         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2159         /* Worst case is that the filename is padded nearly a full block size */
2160         (*namelen) -= cipher_blocksize - 1;
2161 
2162         if ((*namelen) < 0)
2163                 (*namelen) = 0;
2164 
2165         return 0;
2166 }
2167 

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