xref: /linux/fs/ecryptfs/crypto.c (revision 1e1159bb97cf4191849b4b03f77ab32977c2ece6)
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 	       (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 			dst[dst_byte_offset] = 0;
1921 			current_bit_offset = 0;
1922 			break;
1923 		}
1924 		src_byte_offset++;
1925 	}
1926 	(*dst_size) = dst_byte_offset;
1927 out:
1928 	return;
1929 }
1930 
1931 /**
1932  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1933  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1934  * @name: The plaintext name
1935  * @length: The length of the plaintext
1936  * @encoded_name: The encypted name
1937  *
1938  * Encrypts and encodes a filename into something that constitutes a
1939  * valid filename for a filesystem, with printable characters.
1940  *
1941  * We assume that we have a properly initialized crypto context,
1942  * pointed to by crypt_stat->tfm.
1943  *
1944  * Returns zero on success; non-zero on otherwise
1945  */
1946 int ecryptfs_encrypt_and_encode_filename(
1947 	char **encoded_name,
1948 	size_t *encoded_name_size,
1949 	struct ecryptfs_crypt_stat *crypt_stat,
1950 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1951 	const char *name, size_t name_size)
1952 {
1953 	size_t encoded_name_no_prefix_size;
1954 	int rc = 0;
1955 
1956 	(*encoded_name) = NULL;
1957 	(*encoded_name_size) = 0;
1958 	if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
1959 	    || (mount_crypt_stat && (mount_crypt_stat->flags
1960 				     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
1961 		struct ecryptfs_filename *filename;
1962 
1963 		filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1964 		if (!filename) {
1965 			printk(KERN_ERR "%s: Out of memory whilst attempting "
1966 			       "to kzalloc [%zd] bytes\n", __func__,
1967 			       sizeof(*filename));
1968 			rc = -ENOMEM;
1969 			goto out;
1970 		}
1971 		filename->filename = (char *)name;
1972 		filename->filename_size = name_size;
1973 		rc = ecryptfs_encrypt_filename(filename, crypt_stat,
1974 					       mount_crypt_stat);
1975 		if (rc) {
1976 			printk(KERN_ERR "%s: Error attempting to encrypt "
1977 			       "filename; rc = [%d]\n", __func__, rc);
1978 			kfree(filename);
1979 			goto out;
1980 		}
1981 		ecryptfs_encode_for_filename(
1982 			NULL, &encoded_name_no_prefix_size,
1983 			filename->encrypted_filename,
1984 			filename->encrypted_filename_size);
1985 		if ((crypt_stat && (crypt_stat->flags
1986 				    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1987 		    || (mount_crypt_stat
1988 			&& (mount_crypt_stat->flags
1989 			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
1990 			(*encoded_name_size) =
1991 				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1992 				 + encoded_name_no_prefix_size);
1993 		else
1994 			(*encoded_name_size) =
1995 				(ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1996 				 + encoded_name_no_prefix_size);
1997 		(*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1998 		if (!(*encoded_name)) {
1999 			printk(KERN_ERR "%s: Out of memory whilst attempting "
2000 			       "to kzalloc [%zd] bytes\n", __func__,
2001 			       (*encoded_name_size));
2002 			rc = -ENOMEM;
2003 			kfree(filename->encrypted_filename);
2004 			kfree(filename);
2005 			goto out;
2006 		}
2007 		if ((crypt_stat && (crypt_stat->flags
2008 				    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2009 		    || (mount_crypt_stat
2010 			&& (mount_crypt_stat->flags
2011 			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2012 			memcpy((*encoded_name),
2013 			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2014 			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2015 			ecryptfs_encode_for_filename(
2016 			    ((*encoded_name)
2017 			     + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2018 			    &encoded_name_no_prefix_size,
2019 			    filename->encrypted_filename,
2020 			    filename->encrypted_filename_size);
2021 			(*encoded_name_size) =
2022 				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2023 				 + encoded_name_no_prefix_size);
2024 			(*encoded_name)[(*encoded_name_size)] = '\0';
2025 		} else {
2026 			rc = -EOPNOTSUPP;
2027 		}
2028 		if (rc) {
2029 			printk(KERN_ERR "%s: Error attempting to encode "
2030 			       "encrypted filename; rc = [%d]\n", __func__,
2031 			       rc);
2032 			kfree((*encoded_name));
2033 			(*encoded_name) = NULL;
2034 			(*encoded_name_size) = 0;
2035 		}
2036 		kfree(filename->encrypted_filename);
2037 		kfree(filename);
2038 	} else {
2039 		rc = ecryptfs_copy_filename(encoded_name,
2040 					    encoded_name_size,
2041 					    name, name_size);
2042 	}
2043 out:
2044 	return rc;
2045 }
2046 
2047 /**
2048  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2049  * @plaintext_name: The plaintext name
2050  * @plaintext_name_size: The plaintext name size
2051  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2052  * @name: The filename in cipher text
2053  * @name_size: The cipher text name size
2054  *
2055  * Decrypts and decodes the filename.
2056  *
2057  * Returns zero on error; non-zero otherwise
2058  */
2059 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2060 					 size_t *plaintext_name_size,
2061 					 struct super_block *sb,
2062 					 const char *name, size_t name_size)
2063 {
2064 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2065 		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2066 	char *decoded_name;
2067 	size_t decoded_name_size;
2068 	size_t packet_size;
2069 	int rc = 0;
2070 
2071 	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2072 	    && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2073 	    && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2074 	    && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2075 			ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2076 		const char *orig_name = name;
2077 		size_t orig_name_size = name_size;
2078 
2079 		name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2080 		name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2081 		ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2082 					      name, name_size);
2083 		decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2084 		if (!decoded_name) {
2085 			printk(KERN_ERR "%s: Out of memory whilst attempting "
2086 			       "to kmalloc [%zd] bytes\n", __func__,
2087 			       decoded_name_size);
2088 			rc = -ENOMEM;
2089 			goto out;
2090 		}
2091 		ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2092 					      name, name_size);
2093 		rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2094 						  plaintext_name_size,
2095 						  &packet_size,
2096 						  mount_crypt_stat,
2097 						  decoded_name,
2098 						  decoded_name_size);
2099 		if (rc) {
2100 			printk(KERN_INFO "%s: Could not parse tag 70 packet "
2101 			       "from filename; copying through filename "
2102 			       "as-is\n", __func__);
2103 			rc = ecryptfs_copy_filename(plaintext_name,
2104 						    plaintext_name_size,
2105 						    orig_name, orig_name_size);
2106 			goto out_free;
2107 		}
2108 	} else {
2109 		rc = ecryptfs_copy_filename(plaintext_name,
2110 					    plaintext_name_size,
2111 					    name, name_size);
2112 		goto out;
2113 	}
2114 out_free:
2115 	kfree(decoded_name);
2116 out:
2117 	return rc;
2118 }
2119 
2120 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16	143
2121 
2122 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2123 			   struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2124 {
2125 	struct blkcipher_desc desc;
2126 	struct mutex *tfm_mutex;
2127 	size_t cipher_blocksize;
2128 	int rc;
2129 
2130 	if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2131 		(*namelen) = lower_namelen;
2132 		return 0;
2133 	}
2134 
2135 	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2136 			mount_crypt_stat->global_default_fn_cipher_name);
2137 	if (unlikely(rc)) {
2138 		(*namelen) = 0;
2139 		return rc;
2140 	}
2141 
2142 	mutex_lock(tfm_mutex);
2143 	cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2144 	mutex_unlock(tfm_mutex);
2145 
2146 	/* Return an exact amount for the common cases */
2147 	if (lower_namelen == NAME_MAX
2148 	    && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2149 		(*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2150 		return 0;
2151 	}
2152 
2153 	/* Return a safe estimate for the uncommon cases */
2154 	(*namelen) = lower_namelen;
2155 	(*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2156 	/* Since this is the max decoded size, subtract 1 "decoded block" len */
2157 	(*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2158 	(*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2159 	(*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2160 	/* Worst case is that the filename is padded nearly a full block size */
2161 	(*namelen) -= cipher_blocksize - 1;
2162 
2163 	if ((*namelen) < 0)
2164 		(*namelen) = 0;
2165 
2166 	return 0;
2167 }
2168