1	// SPDX-License-Identifier: GPL-2.0-or-later
2	/*
3	* eCryptfs: Linux filesystem encryption layer
4	*
5	* Copyright (C) 1997-2004 Erez Zadok
6	* Copyright (C) 2001-2004 Stony Brook University
7	* Copyright (C) 2004-2007 International Business Machines Corp.
8	* Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
9	* Michael C. Thompson <mcthomps@us.ibm.com>
10	*/
11
12	#include <crypto/skcipher.h>
13	#include <linux/fs.h>
14	#include <linux/mount.h>
15	#include <linux/pagemap.h>
16	#include <linux/random.h>
17	#include <linux/compiler.h>
18	#include <linux/key.h>
19	#include <linux/namei.h>
20	#include <linux/file.h>
21	#include <linux/scatterlist.h>
22	#include <linux/slab.h>
23	#include <linux/unaligned.h>
24	#include <linux/kernel.h>
25	#include <linux/xattr.h>
26	#include "ecryptfs_kernel.h"
27
28	#define DECRYPT 0
29	#define ENCRYPT 1
30
31	/**
32	* ecryptfs_from_hex
33	* @dst: Buffer to take the bytes from src hex; must be at least of
34	* size (src_size / 2)
35	* @src: Buffer to be converted from a hex string representation to raw value
36	* @dst_size: size of dst buffer, or number of hex characters pairs to convert
37	*/
38	void ecryptfs_from_hex(char *dst, char *src, int dst_size)
39	{
40	int x;
41	char tmp[3] = { 0, };
42
43	for (x = 0; x < dst_size; x++) {
44	tmp[0] = src[x * 2];
45	tmp[1] = src[x * 2 + 1];
46	dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
47	}
48	}
49
50	static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
51	char *cipher_name,
52	char *chaining_modifier)
53	{
54	int cipher_name_len = strlen(cipher_name);
55	int chaining_modifier_len = strlen(chaining_modifier);
56	int algified_name_len;
57	int rc;
58
59	algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
60	(*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
61	if (!(*algified_name)) {
62	rc = -ENOMEM;
63	goto out;
64	}
65	snprintf(buf: (*algified_name), size: algified_name_len, fmt: "%s(%s)",
66	chaining_modifier, cipher_name);
67	rc = 0;
68	out:
69	return rc;
70	}
71
72	/**
73	* ecryptfs_derive_iv
74	* @iv: destination for the derived iv vale
75	* @crypt_stat: Pointer to crypt_stat struct for the current inode
76	* @offset: Offset of the extent whose IV we are to derive
77	*
78	* Generate the initialization vector from the given root IV and page
79	* offset.
80	*/
81	void ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
82	loff_t offset)
83	{
84	char dst[MD5_DIGEST_SIZE];
85	char src[ECRYPTFS_MAX_IV_BYTES + 16];
86
87	if (unlikely(ecryptfs_verbosity > 0)) {
88	ecryptfs_printk(KERN_DEBUG, "root iv:\n");
89	ecryptfs_dump_hex(data: crypt_stat->root_iv, bytes: crypt_stat->iv_bytes);
90	}
91	/* TODO: It is probably secure to just cast the least
92	* significant bits of the root IV into an unsigned long and
93	* add the offset to that rather than go through all this
94	* hashing business. -Halcrow */
95	memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
96	memset((src + crypt_stat->iv_bytes), 0, 16);
97	snprintf(buf: (src + crypt_stat->iv_bytes), size: 16, fmt: "%lld", offset);
98	if (unlikely(ecryptfs_verbosity > 0)) {
99	ecryptfs_printk(KERN_DEBUG, "source:\n");
100	ecryptfs_dump_hex(data: src, bytes: (crypt_stat->iv_bytes + 16));
101	}
102	md5(data: src, len: crypt_stat->iv_bytes + 16, out: dst);
103	memcpy(iv, dst, crypt_stat->iv_bytes);
104	if (unlikely(ecryptfs_verbosity > 0)) {
105	ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
106	ecryptfs_dump_hex(data: iv, bytes: crypt_stat->iv_bytes);
107	}
108	}
109
110	/**
111	* ecryptfs_init_crypt_stat
112	* @crypt_stat: Pointer to the crypt_stat struct to initialize.
113	*
114	* Initialize the crypt_stat structure.
115	*/
116	void ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
117	{
118	memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
119	INIT_LIST_HEAD(list: &crypt_stat->keysig_list);
120	mutex_init(&crypt_stat->keysig_list_mutex);
121	mutex_init(&crypt_stat->cs_mutex);
122	mutex_init(&crypt_stat->cs_tfm_mutex);
123	crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
124	}
125
126	/**
127	* ecryptfs_destroy_crypt_stat
128	* @crypt_stat: Pointer to the crypt_stat struct to initialize.
129	*
130	* Releases all memory associated with a crypt_stat struct.
131	*/
132	void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
133	{
134	struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
135
136	crypto_free_skcipher(tfm: crypt_stat->tfm);
137	list_for_each_entry_safe(key_sig, key_sig_tmp,
138	&crypt_stat->keysig_list, crypt_stat_list) {
139	list_del(entry: &key_sig->crypt_stat_list);
140	kmem_cache_free(s: ecryptfs_key_sig_cache, objp: key_sig);
141	}
142	memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
143	}
144
145	void ecryptfs_destroy_mount_crypt_stat(
146	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
147	{
148	struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
149
150	if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
151	return;
152	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
153	list_for_each_entry_safe(auth_tok, auth_tok_tmp,
154	&mount_crypt_stat->global_auth_tok_list,
155	mount_crypt_stat_list) {
156	list_del(entry: &auth_tok->mount_crypt_stat_list);
157	if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
158	key_put(key: auth_tok->global_auth_tok_key);
159	kmem_cache_free(s: ecryptfs_global_auth_tok_cache, objp: auth_tok);
160	}
161	mutex_unlock(lock: &mount_crypt_stat->global_auth_tok_list_mutex);
162	memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
163	}
164
165	/**
166	* virt_to_scatterlist
167	* @addr: Virtual address
168	* @size: Size of data; should be an even multiple of the block size
169	* @sg: Pointer to scatterlist array; set to NULL to obtain only
170	* the number of scatterlist structs required in array
171	* @sg_size: Max array size
172	*
173	* Fills in a scatterlist array with page references for a passed
174	* virtual address.
175	*
176	* Returns the number of scatterlist structs in array used
177	*/
178	int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
179	int sg_size)
180	{
181	int i = 0;
182	struct page *pg;
183	int offset;
184	int remainder_of_page;
185
186	sg_init_table(sg, sg_size);
187
188	while (size > 0 && i < sg_size) {
189	pg = virt_to_page(addr);
190	offset = offset_in_page(addr);
191	sg_set_page(sg: &sg[i], page: pg, len: 0, offset);
192	remainder_of_page = PAGE_SIZE - offset;
193	if (size >= remainder_of_page) {
194	sg[i].length = remainder_of_page;
195	addr += remainder_of_page;
196	size -= remainder_of_page;
197	} else {
198	sg[i].length = size;
199	addr += size;
200	size = 0;
201	}
202	i++;
203	}
204	if (size > 0)
205	return -ENOMEM;
206	return i;
207	}
208
209	/**
210	* crypt_scatterlist
211	* @crypt_stat: Pointer to the crypt_stat struct to initialize.
212	* @dst_sg: Destination of the data after performing the crypto operation
213	* @src_sg: Data to be encrypted or decrypted
214	* @size: Length of data
215	* @iv: IV to use
216	* @op: ENCRYPT or DECRYPT to indicate the desired operation
217	*
218	* Returns the number of bytes encrypted or decrypted; negative value on error
219	*/
220	static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
221	struct scatterlist *dst_sg,
222	struct scatterlist *src_sg, int size,
223	unsigned char *iv, int op)
224	{
225	struct skcipher_request *req = NULL;
226	DECLARE_CRYPTO_WAIT(ecr);
227	int rc = 0;
228
229	if (unlikely(ecryptfs_verbosity > 0)) {
230	ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
231	crypt_stat->key_size);
232	ecryptfs_dump_hex(data: crypt_stat->key,
233	bytes: crypt_stat->key_size);
234	}
235
236	mutex_lock(&crypt_stat->cs_tfm_mutex);
237	req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
238	if (!req) {
239	mutex_unlock(lock: &crypt_stat->cs_tfm_mutex);
240	rc = -ENOMEM;
241	goto out;
242	}
243
244	skcipher_request_set_callback(req,
245	CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
246	compl: crypto_req_done, data: &ecr);
247	/* Consider doing this once, when the file is opened */
248	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
249	rc = crypto_skcipher_setkey(tfm: crypt_stat->tfm, key: crypt_stat->key,
250	keylen: crypt_stat->key_size);
251	if (rc) {
252	ecryptfs_printk(KERN_ERR,
253	"Error setting key; rc = [%d]\n",
254	rc);
255	mutex_unlock(lock: &crypt_stat->cs_tfm_mutex);
256	rc = -EINVAL;
257	goto out;
258	}
259	crypt_stat->flags |= ECRYPTFS_KEY_SET;
260	}
261	mutex_unlock(lock: &crypt_stat->cs_tfm_mutex);
262	skcipher_request_set_crypt(req, src: src_sg, dst: dst_sg, cryptlen: size, iv);
263	rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
264	crypto_skcipher_decrypt(req);
265	rc = crypto_wait_req(err: rc, wait: &ecr);
266	out:
267	skcipher_request_free(req);
268	return rc;
269	}
270
271	/*
272	* lower_offset_for_page
273	*
274	* Convert an eCryptfs page index into a lower byte offset
275	*/
276	static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
277	struct folio *folio)
278	{
279	return ecryptfs_lower_header_size(crypt_stat) +
280	(loff_t)folio->index * PAGE_SIZE;
281	}
282
283	/**
284	* crypt_extent
285	* @crypt_stat: crypt_stat containing cryptographic context for the
286	* encryption operation
287	* @dst_page: The page to write the result into
288	* @src_page: The page to read from
289	* @page_index: The offset in the file (in units of PAGE_SIZE)
290	* @extent_offset: Page extent offset for use in generating IV
291	* @op: ENCRYPT or DECRYPT to indicate the desired operation
292	*
293	* Encrypts or decrypts one extent of data.
294	*
295	* Return zero on success; non-zero otherwise
296	*/
297	static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
298	struct page *dst_page,
299	struct page *src_page,
300	pgoff_t page_index,
301	unsigned long extent_offset, int op)
302	{
303	loff_t extent_base;
304	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
305	struct scatterlist src_sg, dst_sg;
306	size_t extent_size = crypt_stat->extent_size;
307	int rc;
308
309	extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
310	ecryptfs_derive_iv(iv: extent_iv, crypt_stat, offset: extent_base + extent_offset);
311
312	sg_init_table(&src_sg, 1);
313	sg_init_table(&dst_sg, 1);
314
315	sg_set_page(sg: &src_sg, page: src_page, len: extent_size,
316	offset: extent_offset * extent_size);
317	sg_set_page(sg: &dst_sg, page: dst_page, len: extent_size,
318	offset: extent_offset * extent_size);
319
320	rc = crypt_scatterlist(crypt_stat, dst_sg: &dst_sg, src_sg: &src_sg, size: extent_size,
321	iv: extent_iv, op);
322	if (rc < 0) {
323	printk(KERN_ERR "%s: Error attempting to crypt page with "
324	"page_index = [%ld], extent_offset = [%ld]; "
325	"rc = [%d]\n", __func__, page_index, extent_offset, rc);
326	goto out;
327	}
328	rc = 0;
329	out:
330	return rc;
331	}
332
333	/**
334	* ecryptfs_encrypt_page
335	* @folio: Folio mapped from the eCryptfs inode for the file; contains
336	* decrypted content that needs to be encrypted (to a temporary
337	* page; not in place) and written out to the lower file
338	*
339	* Encrypt an eCryptfs page. This is done on a per-extent basis. Note
340	* that eCryptfs pages may straddle the lower pages -- for instance,
341	* if the file was created on a machine with an 8K page size
342	* (resulting in an 8K header), and then the file is copied onto a
343	* host with a 32K page size, then when reading page 0 of the eCryptfs
344	* file, 24K of page 0 of the lower file will be read and decrypted,
345	* and then 8K of page 1 of the lower file will be read and decrypted.
346	*
347	* Returns zero on success; negative on error
348	*/
349	int ecryptfs_encrypt_page(struct folio *folio)
350	{
351	struct inode *ecryptfs_inode;
352	struct ecryptfs_crypt_stat *crypt_stat;
353	char *enc_extent_virt;
354	struct page *enc_extent_page = NULL;
355	loff_t extent_offset;
356	loff_t lower_offset;
357	int rc = 0;
358
359	ecryptfs_inode = folio->mapping->host;
360	crypt_stat =
361	&(ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat);
362	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
363	enc_extent_page = alloc_page(GFP_USER);
364	if (!enc_extent_page) {
365	rc = -ENOMEM;
366	ecryptfs_printk(KERN_ERR, "Error allocating memory for "
367	"encrypted extent\n");
368	goto out;
369	}
370
371	for (extent_offset = 0;
372	extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
373	extent_offset++) {
374	rc = crypt_extent(crypt_stat, dst_page: enc_extent_page,
375	folio_page(folio, 0), page_index: folio->index,
376	extent_offset, ENCRYPT);
377	if (rc) {
378	printk(KERN_ERR "%s: Error encrypting extent; "
379	"rc = [%d]\n", __func__, rc);
380	goto out;
381	}
382	}
383
384	lower_offset = lower_offset_for_page(crypt_stat, folio);
385	enc_extent_virt = kmap_local_page(page: enc_extent_page);
386	rc = ecryptfs_write_lower(ecryptfs_inode, data: enc_extent_virt, offset: lower_offset,
387	PAGE_SIZE);
388	kunmap_local(enc_extent_virt);
389	if (rc < 0) {
390	ecryptfs_printk(KERN_ERR,
391	"Error attempting to write lower page; rc = [%d]\n",
392	rc);
393	goto out;
394	}
395	rc = 0;
396	out:
397	if (enc_extent_page) {
398	__free_page(enc_extent_page);
399	}
400	return rc;
401	}
402
403	/**
404	* ecryptfs_decrypt_page
405	* @folio: Folio mapped from the eCryptfs inode for the file; data read
406	* and decrypted from the lower file will be written into this
407	* page
408	*
409	* Decrypt an eCryptfs page. This is done on a per-extent basis. Note
410	* that eCryptfs pages may straddle the lower pages -- for instance,
411	* if the file was created on a machine with an 8K page size
412	* (resulting in an 8K header), and then the file is copied onto a
413	* host with a 32K page size, then when reading page 0 of the eCryptfs
414	* file, 24K of page 0 of the lower file will be read and decrypted,
415	* and then 8K of page 1 of the lower file will be read and decrypted.
416	*
417	* Returns zero on success; negative on error
418	*/
419	int ecryptfs_decrypt_page(struct folio *folio)
420	{
421	struct inode *ecryptfs_inode;
422	struct ecryptfs_crypt_stat *crypt_stat;
423	char *page_virt;
424	unsigned long extent_offset;
425	loff_t lower_offset;
426	int rc = 0;
427
428	ecryptfs_inode = folio->mapping->host;
429	crypt_stat =
430	&(ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat);
431	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
432
433	lower_offset = lower_offset_for_page(crypt_stat, folio);
434	page_virt = kmap_local_folio(folio, offset: 0);
435	rc = ecryptfs_read_lower(data: page_virt, offset: lower_offset, PAGE_SIZE,
436	ecryptfs_inode);
437	kunmap_local(page_virt);
438	if (rc < 0) {
439	ecryptfs_printk(KERN_ERR,
440	"Error attempting to read lower page; rc = [%d]\n",
441	rc);
442	goto out;
443	}
444
445	for (extent_offset = 0;
446	extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
447	extent_offset++) {
448	struct page *page = folio_page(folio, 0);
449	rc = crypt_extent(crypt_stat, dst_page: page, src_page: page, page_index: folio->index,
450	extent_offset, DECRYPT);
451	if (rc) {
452	printk(KERN_ERR "%s: Error decrypting extent; "
453	"rc = [%d]\n", __func__, rc);
454	goto out;
455	}
456	}
457	out:
458	return rc;
459	}
460
461	#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
462
463	/**
464	* ecryptfs_init_crypt_ctx
465	* @crypt_stat: Uninitialized crypt stats structure
466	*
467	* Initialize the crypto context.
468	*
469	* TODO: Performance: Keep a cache of initialized cipher contexts;
470	* only init if needed
471	*/
472	int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
473	{
474	char *full_alg_name;
475	int rc = -EINVAL;
476
477	ecryptfs_printk(KERN_DEBUG,
478	"Initializing cipher [%s]; strlen = [%d]; "
479	"key_size_bits = [%zd]\n",
480	crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
481	crypt_stat->key_size << 3);
482	mutex_lock(&crypt_stat->cs_tfm_mutex);
483	if (crypt_stat->tfm) {
484	rc = 0;
485	goto out_unlock;
486	}
487	rc = ecryptfs_crypto_api_algify_cipher_name(algified_name: &full_alg_name,
488	cipher_name: crypt_stat->cipher, chaining_modifier: "cbc");
489	if (rc)
490	goto out_unlock;
491	crypt_stat->tfm = crypto_alloc_skcipher(alg_name: full_alg_name, type: 0, mask: 0);
492	if (IS_ERR(ptr: crypt_stat->tfm)) {
493	rc = PTR_ERR(ptr: crypt_stat->tfm);
494	crypt_stat->tfm = NULL;
495	ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
496	"Error initializing cipher [%s]\n",
497	full_alg_name);
498	goto out_free;
499	}
500	crypto_skcipher_set_flags(tfm: crypt_stat->tfm,
501	CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
502	rc = 0;
503	out_free:
504	kfree(objp: full_alg_name);
505	out_unlock:
506	mutex_unlock(lock: &crypt_stat->cs_tfm_mutex);
507	return rc;
508	}
509
510	static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
511	{
512	int extent_size_tmp;
513
514	crypt_stat->extent_mask = 0xFFFFFFFF;
515	crypt_stat->extent_shift = 0;
516	if (crypt_stat->extent_size == 0)
517	return;
518	extent_size_tmp = crypt_stat->extent_size;
519	while ((extent_size_tmp & 0x01) == 0) {
520	extent_size_tmp >>= 1;
521	crypt_stat->extent_mask <<= 1;
522	crypt_stat->extent_shift++;
523	}
524	}
525
526	void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
527	{
528	/* Default values; may be overwritten as we are parsing the
529	* packets. */
530	crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
531	set_extent_mask_and_shift(crypt_stat);
532	crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
533	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
534	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
535	else {
536	if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
537	crypt_stat->metadata_size =
538	ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
539	else
540	crypt_stat->metadata_size = PAGE_SIZE;
541	}
542	}
543
544	/*
545	* ecryptfs_compute_root_iv
546	*
547	* On error, sets the root IV to all 0's.
548	*/
549	int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
550	{
551	char dst[MD5_DIGEST_SIZE];
552
553	BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
554	BUG_ON(crypt_stat->iv_bytes <= 0);
555	if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
556	ecryptfs_printk(KERN_WARNING, "Session key not valid; "
557	"cannot generate root IV\n");
558	memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
559	crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
560	return -EINVAL;
561	}
562	md5(data: crypt_stat->key, len: crypt_stat->key_size, out: dst);
563	memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
564	return 0;
565	}
566
567	static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
568	{
569	get_random_bytes(buf: crypt_stat->key, len: crypt_stat->key_size);
570	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
571	ecryptfs_compute_root_iv(crypt_stat);
572	if (unlikely(ecryptfs_verbosity > 0)) {
573	ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
574	ecryptfs_dump_hex(data: crypt_stat->key,
575	bytes: crypt_stat->key_size);
576	}
577	}
578
579	/**
580	* ecryptfs_copy_mount_wide_flags_to_inode_flags
581	* @crypt_stat: The inode's cryptographic context
582	* @mount_crypt_stat: The mount point's cryptographic context
583	*
584	* This function propagates the mount-wide flags to individual inode
585	* flags.
586	*/
587	static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
588	struct ecryptfs_crypt_stat *crypt_stat,
589	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
590	{
591	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
592	crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
593	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
594	crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
595	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
596	crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
597	if (mount_crypt_stat->flags
598	& ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
599	crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
600	else if (mount_crypt_stat->flags
601	& ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
602	crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
603	}
604	}
605
606	static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
607	struct ecryptfs_crypt_stat *crypt_stat,
608	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
609	{
610	struct ecryptfs_global_auth_tok *global_auth_tok;
611	int rc = 0;
612
613	mutex_lock(&crypt_stat->keysig_list_mutex);
614	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
615
616	list_for_each_entry(global_auth_tok,
617	&mount_crypt_stat->global_auth_tok_list,
618	mount_crypt_stat_list) {
619	if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
620	continue;
621	rc = ecryptfs_add_keysig(crypt_stat, sig: global_auth_tok->sig);
622	if (rc) {
623	printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
624	goto out;
625	}
626	}
627
628	out:
629	mutex_unlock(lock: &mount_crypt_stat->global_auth_tok_list_mutex);
630	mutex_unlock(lock: &crypt_stat->keysig_list_mutex);
631	return rc;
632	}
633
634	/**
635	* ecryptfs_set_default_crypt_stat_vals
636	* @crypt_stat: The inode's cryptographic context
637	* @mount_crypt_stat: The mount point's cryptographic context
638	*
639	* Default values in the event that policy does not override them.
640	*/
641	static void ecryptfs_set_default_crypt_stat_vals(
642	struct ecryptfs_crypt_stat *crypt_stat,
643	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
644	{
645	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
646	mount_crypt_stat);
647	ecryptfs_set_default_sizes(crypt_stat);
648	strcpy(p: crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
649	crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
650	crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
651	crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
652	crypt_stat->mount_crypt_stat = mount_crypt_stat;
653	}
654
655	/**
656	* ecryptfs_new_file_context
657	* @ecryptfs_inode: The eCryptfs inode
658	*
659	* If the crypto context for the file has not yet been established,
660	* this is where we do that. Establishing a new crypto context
661	* involves the following decisions:
662	* - What cipher to use?
663	* - What set of authentication tokens to use?
664	* Here we just worry about getting enough information into the
665	* authentication tokens so that we know that they are available.
666	* We associate the available authentication tokens with the new file
667	* via the set of signatures in the crypt_stat struct. Later, when
668	* the headers are actually written out, we may again defer to
669	* userspace to perform the encryption of the session key; for the
670	* foreseeable future, this will be the case with public key packets.
671	*
672	* Returns zero on success; non-zero otherwise
673	*/
674	int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
675	{
676	struct ecryptfs_crypt_stat *crypt_stat =
677	&ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat;
678	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
679	&ecryptfs_superblock_to_private(
680	sb: ecryptfs_inode->i_sb)->mount_crypt_stat;
681	int cipher_name_len;
682	int rc = 0;
683
684	ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
685	crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
686	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
687	mount_crypt_stat);
688	rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
689	mount_crypt_stat);
690	if (rc) {
691	printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
692	"to the inode key sigs; rc = [%d]\n", rc);
693	goto out;
694	}
695	cipher_name_len =
696	strlen(mount_crypt_stat->global_default_cipher_name);
697	memcpy(crypt_stat->cipher,
698	mount_crypt_stat->global_default_cipher_name,
699	cipher_name_len);
700	crypt_stat->cipher[cipher_name_len] = '\0';
701	crypt_stat->key_size =
702	mount_crypt_stat->global_default_cipher_key_size;
703	ecryptfs_generate_new_key(crypt_stat);
704	rc = ecryptfs_init_crypt_ctx(crypt_stat);
705	if (rc)
706	ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
707	"context for cipher [%s]: rc = [%d]\n",
708	crypt_stat->cipher, rc);
709	out:
710	return rc;
711	}
712
713	/**
714	* ecryptfs_validate_marker - check for the ecryptfs marker
715	* @data: The data block in which to check
716	*
717	* Returns zero if marker found; -EINVAL if not found
718	*/
719	static int ecryptfs_validate_marker(char *data)
720	{
721	u32 m_1, m_2;
722
723	m_1 = get_unaligned_be32(p: data);
724	m_2 = get_unaligned_be32(p: data + 4);
725	if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
726	return 0;
727	ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
728	"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
729	MAGIC_ECRYPTFS_MARKER);
730	ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
731	"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
732	return -EINVAL;
733	}
734
735	struct ecryptfs_flag_map_elem {
736	u32 file_flag;
737	u32 local_flag;
738	};
739
740	/* Add support for additional flags by adding elements here. */
741	static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
742	{0x00000001, ECRYPTFS_ENABLE_HMAC},
743	{0x00000002, ECRYPTFS_ENCRYPTED},
744	{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
745	{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
746	};
747
748	/**
749	* ecryptfs_process_flags
750	* @crypt_stat: The cryptographic context
751	* @page_virt: Source data to be parsed
752	* @bytes_read: Updated with the number of bytes read
753	*/
754	static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
755	char *page_virt, int *bytes_read)
756	{
757	int i;
758	u32 flags;
759
760	flags = get_unaligned_be32(p: page_virt);
761	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
762	if (flags & ecryptfs_flag_map[i].file_flag) {
763	crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
764	} else
765	crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
766	/* Version is in top 8 bits of the 32-bit flag vector */
767	crypt_stat->file_version = ((flags >> 24) & 0xFF);
768	(*bytes_read) = 4;
769	}
770
771	/**
772	* write_ecryptfs_marker
773	* @page_virt: The pointer to in a page to begin writing the marker
774	* @written: Number of bytes written
775	*
776	* Marker = 0x3c81b7f5
777	*/
778	static void write_ecryptfs_marker(char *page_virt, size_t *written)
779	{
780	u32 m_1, m_2;
781
782	get_random_bytes(buf: &m_1, len: (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
783	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
784	put_unaligned_be32(val: m_1, p: page_virt);
785	page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
786	put_unaligned_be32(val: m_2, p: page_virt);
787	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
788	}
789
790	void ecryptfs_write_crypt_stat_flags(char *page_virt,
791	struct ecryptfs_crypt_stat *crypt_stat,
792	size_t *written)
793	{
794	u32 flags = 0;
795	int i;
796
797	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
798	if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
799	flags |= ecryptfs_flag_map[i].file_flag;
800	/* Version is in top 8 bits of the 32-bit flag vector */
801	flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
802	put_unaligned_be32(val: flags, p: page_virt);
803	(*written) = 4;
804	}
805
806	struct ecryptfs_cipher_code_str_map_elem {
807	char cipher_str[16];
808	u8 cipher_code;
809	};
810
811	/* Add support for additional ciphers by adding elements here. The
812	* cipher_code is whatever OpenPGP applications use to identify the
813	* ciphers. List in order of probability. */
814	static struct ecryptfs_cipher_code_str_map_elem
815	ecryptfs_cipher_code_str_map[] = {
816	{"aes",RFC2440_CIPHER_AES_128 },
817	{"blowfish", RFC2440_CIPHER_BLOWFISH},
818	{"des3_ede", RFC2440_CIPHER_DES3_EDE},
819	{"cast5", RFC2440_CIPHER_CAST_5},
820	{"twofish", RFC2440_CIPHER_TWOFISH},
821	{"cast6", RFC2440_CIPHER_CAST_6},
822	{"aes", RFC2440_CIPHER_AES_192},
823	{"aes", RFC2440_CIPHER_AES_256}
824	};
825
826	/**
827	* ecryptfs_code_for_cipher_string
828	* @cipher_name: The string alias for the cipher
829	* @key_bytes: Length of key in bytes; used for AES code selection
830	*
831	* Returns zero on no match, or the cipher code on match
832	*/
833	u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
834	{
835	int i;
836	u8 code = 0;
837	struct ecryptfs_cipher_code_str_map_elem *map =
838	ecryptfs_cipher_code_str_map;
839
840	if (strcmp(cipher_name, "aes") == 0) {
841	switch (key_bytes) {
842	case 16:
843	code = RFC2440_CIPHER_AES_128;
844	break;
845	case 24:
846	code = RFC2440_CIPHER_AES_192;
847	break;
848	case 32:
849	code = RFC2440_CIPHER_AES_256;
850	}
851	} else {
852	for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
853	if (strcmp(cipher_name, map[i].cipher_str) == 0) {
854	code = map[i].cipher_code;
855	break;
856	}
857	}
858	return code;
859	}
860
861	/**
862	* ecryptfs_cipher_code_to_string
863	* @str: Destination to write out the cipher name
864	* @cipher_code: The code to convert to cipher name string
865	*
866	* Returns zero on success
867	*/
868	int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
869	{
870	int rc = 0;
871	int i;
872
873	str[0] = '\0';
874	for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
875	if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
876	strcpy(p: str, q: ecryptfs_cipher_code_str_map[i].cipher_str);
877	if (str[0] == '\0') {
878	ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
879	"[%d]\n", cipher_code);
880	rc = -EINVAL;
881	}
882	return rc;
883	}
884
885	int ecryptfs_read_and_validate_header_region(struct inode *inode)
886	{
887	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
888	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
889	int rc;
890
891	rc = ecryptfs_read_lower(data: file_size, offset: 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
892	ecryptfs_inode: inode);
893	if (rc < 0)
894	return rc;
895	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
896	return -EINVAL;
897	rc = ecryptfs_validate_marker(data: marker);
898	if (!rc)
899	ecryptfs_i_size_init(page_virt: file_size, inode);
900	return rc;
901	}
902
903	void
904	ecryptfs_write_header_metadata(char *virt,
905	struct ecryptfs_crypt_stat *crypt_stat,
906	size_t *written)
907	{
908	u32 header_extent_size;
909	u16 num_header_extents_at_front;
910
911	header_extent_size = (u32)crypt_stat->extent_size;
912	num_header_extents_at_front =
913	(u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
914	put_unaligned_be32(val: header_extent_size, p: virt);
915	virt += 4;
916	put_unaligned_be16(val: num_header_extents_at_front, p: virt);
917	(*written) = 6;
918	}
919
920	struct kmem_cache *ecryptfs_header_cache;
921
922	/**
923	* ecryptfs_write_headers_virt
924	* @page_virt: The virtual address to write the headers to
925	* @max: The size of memory allocated at page_virt
926	* @size: Set to the number of bytes written by this function
927	* @crypt_stat: The cryptographic context
928	* @ecryptfs_dentry: The eCryptfs dentry
929	*
930	* Format version: 1
931	*
932	* Header Extent:
933	* Octets 0-7: Unencrypted file size (big-endian)
934	* Octets 8-15: eCryptfs special marker
935	* Octets 16-19: Flags
936	* Octet 16: File format version number (between 0 and 255)
937	* Octets 17-18: Reserved
938	* Octet 19: Bit 1 (lsb): Reserved
939	* Bit 2: Encrypted?
940	* Bits 3-8: Reserved
941	* Octets 20-23: Header extent size (big-endian)
942	* Octets 24-25: Number of header extents at front of file
943	* (big-endian)
944	* Octet 26: Begin RFC 2440 authentication token packet set
945	* Data Extent 0:
946	* Lower data (CBC encrypted)
947	* Data Extent 1:
948	* Lower data (CBC encrypted)
949	* ...
950	*
951	* Returns zero on success
952	*/
953	static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
954	size_t *size,
955	struct ecryptfs_crypt_stat *crypt_stat,
956	struct dentry *ecryptfs_dentry)
957	{
958	int rc;
959	size_t written;
960	size_t offset;
961
962	offset = ECRYPTFS_FILE_SIZE_BYTES;
963	write_ecryptfs_marker(page_virt: (page_virt + offset), written: &written);
964	offset += written;
965	ecryptfs_write_crypt_stat_flags(page_virt: (page_virt + offset), crypt_stat,
966	written: &written);
967	offset += written;
968	ecryptfs_write_header_metadata(virt: (page_virt + offset), crypt_stat,
969	written: &written);
970	offset += written;
971	rc = ecryptfs_generate_key_packet_set(dest_base: (page_virt + offset), crypt_stat,
972	ecryptfs_dentry, len: &written,
973	max: max - offset);
974	if (rc)
975	ecryptfs_printk(KERN_WARNING, "Error generating key packet "
976	"set; rc = [%d]\n", rc);
977	if (size) {
978	offset += written;
979	*size = offset;
980	}
981	return rc;
982	}
983
984	static int
985	ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
986	char *virt, size_t virt_len)
987	{
988	int rc;
989
990	rc = ecryptfs_write_lower(ecryptfs_inode, data: virt,
991	offset: 0, size: virt_len);
992	if (rc < 0)
993	printk(KERN_ERR "%s: Error attempting to write header "
994	"information to lower file; rc = [%d]\n", __func__, rc);
995	else
996	rc = 0;
997	return rc;
998	}
999
1000	static int
1001	ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1002	struct inode *ecryptfs_inode,
1003	char *page_virt, size_t size)
1004	{
1005	int rc;
1006	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry: ecryptfs_dentry);
1007	struct inode *lower_inode = d_inode(dentry: lower_dentry);
1008
1009	if (!(lower_inode->i_opflags & IOP_XATTR)) {
1010	rc = -EOPNOTSUPP;
1011	goto out;
1012	}
1013
1014	inode_lock(inode: lower_inode);
1015	rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
1016	ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1017	if (!rc && ecryptfs_inode)
1018	fsstack_copy_attr_all(dest: ecryptfs_inode, src: lower_inode);
1019	inode_unlock(inode: lower_inode);
1020	out:
1021	return rc;
1022	}
1023
1024	static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1025	unsigned int order)
1026	{
1027	struct page *page;
1028
1029	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1030	if (page)
1031	return (unsigned long) page_address(page);
1032	return 0;
1033	}
1034
1035	/**
1036	* ecryptfs_write_metadata
1037	* @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1038	* @ecryptfs_inode: The newly created eCryptfs inode
1039	*
1040	* Write the file headers out. This will likely involve a userspace
1041	* callout, in which the session key is encrypted with one or more
1042	* public keys and/or the passphrase necessary to do the encryption is
1043	* retrieved via a prompt. Exactly what happens at this point should
1044	* be policy-dependent.
1045	*
1046	* Returns zero on success; non-zero on error
1047	*/
1048	int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1049	struct inode *ecryptfs_inode)
1050	{
1051	struct ecryptfs_crypt_stat *crypt_stat =
1052	&ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat;
1053	unsigned int order;
1054	char *virt;
1055	size_t virt_len;
1056	size_t size = 0;
1057	int rc = 0;
1058
1059	if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1060	if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1061	printk(KERN_ERR "Key is invalid; bailing out\n");
1062	rc = -EINVAL;
1063	goto out;
1064	}
1065	} else {
1066	printk(KERN_WARNING "%s: Encrypted flag not set\n",
1067	__func__);
1068	rc = -EINVAL;
1069	goto out;
1070	}
1071	virt_len = crypt_stat->metadata_size;
1072	order = get_order(size: virt_len);
1073	/* Released in this function */
1074	virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1075	if (!virt) {
1076	printk(KERN_ERR "%s: Out of memory\n", __func__);
1077	rc = -ENOMEM;
1078	goto out;
1079	}
1080	/* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1081	rc = ecryptfs_write_headers_virt(page_virt: virt, max: virt_len, size: &size, crypt_stat,
1082	ecryptfs_dentry);
1083	if (unlikely(rc)) {
1084	printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1085	__func__, rc);
1086	goto out_free;
1087	}
1088	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1089	rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1090	page_virt: virt, size);
1091	else
1092	rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1093	virt_len);
1094	if (rc) {
1095	printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1096	"rc = [%d]\n", __func__, rc);
1097	goto out_free;
1098	}
1099	out_free:
1100	free_pages(addr: (unsigned long)virt, order);
1101	out:
1102	return rc;
1103	}
1104
1105	#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1106	#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1107	static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1108	char *virt, int *bytes_read,
1109	int validate_header_size)
1110	{
1111	int rc = 0;
1112	u32 header_extent_size;
1113	u16 num_header_extents_at_front;
1114
1115	header_extent_size = get_unaligned_be32(p: virt);
1116	virt += sizeof(__be32);
1117	num_header_extents_at_front = get_unaligned_be16(p: virt);
1118	crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1119	* (size_t)header_extent_size));
1120	(*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1121	if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1122	&& (crypt_stat->metadata_size
1123	< ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1124	rc = -EINVAL;
1125	printk(KERN_WARNING "Invalid header size: [%zd]\n",
1126	crypt_stat->metadata_size);
1127	}
1128	return rc;
1129	}
1130
1131	/**
1132	* set_default_header_data
1133	* @crypt_stat: The cryptographic context
1134	*
1135	* For version 0 file format; this function is only for backwards
1136	* compatibility for files created with the prior versions of
1137	* eCryptfs.
1138	*/
1139	static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1140	{
1141	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1142	}
1143
1144	void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1145	{
1146	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1147	struct ecryptfs_crypt_stat *crypt_stat;
1148	u64 file_size;
1149
1150	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1151	mount_crypt_stat =
1152	&ecryptfs_superblock_to_private(sb: inode->i_sb)->mount_crypt_stat;
1153	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1154	file_size = i_size_read(inode: ecryptfs_inode_to_lower(inode));
1155	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1156	file_size += crypt_stat->metadata_size;
1157	} else
1158	file_size = get_unaligned_be64(p: page_virt);
1159	i_size_write(inode, i_size: (loff_t)file_size);
1160	crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1161	}
1162
1163	/**
1164	* ecryptfs_read_headers_virt
1165	* @page_virt: The virtual address into which to read the headers
1166	* @crypt_stat: The cryptographic context
1167	* @ecryptfs_dentry: The eCryptfs dentry
1168	* @validate_header_size: Whether to validate the header size while reading
1169	*
1170	* Read/parse the header data. The header format is detailed in the
1171	* comment block for the ecryptfs_write_headers_virt() function.
1172	*
1173	* Returns zero on success
1174	*/
1175	static int ecryptfs_read_headers_virt(char *page_virt,
1176	struct ecryptfs_crypt_stat *crypt_stat,
1177	struct dentry *ecryptfs_dentry,
1178	int validate_header_size)
1179	{
1180	int rc = 0;
1181	int offset;
1182	int bytes_read;
1183
1184	ecryptfs_set_default_sizes(crypt_stat);
1185	crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1186	sb: ecryptfs_dentry->d_sb)->mount_crypt_stat;
1187	offset = ECRYPTFS_FILE_SIZE_BYTES;
1188	rc = ecryptfs_validate_marker(data: page_virt + offset);
1189	if (rc)
1190	goto out;
1191	if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1192	ecryptfs_i_size_init(page_virt, inode: d_inode(dentry: ecryptfs_dentry));
1193	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1194	ecryptfs_process_flags(crypt_stat, page_virt: (page_virt + offset), bytes_read: &bytes_read);
1195	if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1196	ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1197	"file version [%d] is supported by this "
1198	"version of eCryptfs\n",
1199	crypt_stat->file_version,
1200	ECRYPTFS_SUPPORTED_FILE_VERSION);
1201	rc = -EINVAL;
1202	goto out;
1203	}
1204	offset += bytes_read;
1205	if (crypt_stat->file_version >= 1) {
1206	rc = parse_header_metadata(crypt_stat, virt: (page_virt + offset),
1207	bytes_read: &bytes_read, validate_header_size);
1208	if (rc) {
1209	ecryptfs_printk(KERN_WARNING, "Error reading header "
1210	"metadata; rc = [%d]\n", rc);
1211	}
1212	offset += bytes_read;
1213	} else
1214	set_default_header_data(crypt_stat);
1215	rc = ecryptfs_parse_packet_set(crypt_stat, src: (page_virt + offset),
1216	ecryptfs_dentry);
1217	out:
1218	return rc;
1219	}
1220
1221	/**
1222	* ecryptfs_read_xattr_region
1223	* @page_virt: The vitual address into which to read the xattr data
1224	* @ecryptfs_inode: The eCryptfs inode
1225	*
1226	* Attempts to read the crypto metadata from the extended attribute
1227	* region of the lower file.
1228	*
1229	* Returns zero on success; non-zero on error
1230	*/
1231	int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1232	{
1233	struct dentry *lower_dentry =
1234	ecryptfs_inode_to_private(inode: ecryptfs_inode)->lower_file->f_path.dentry;
1235	ssize_t size;
1236	int rc = 0;
1237
1238	size = ecryptfs_getxattr_lower(lower_dentry,
1239	lower_inode: ecryptfs_inode_to_lower(inode: ecryptfs_inode),
1240	ECRYPTFS_XATTR_NAME,
1241	value: page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1242	if (size < 0) {
1243	if (unlikely(ecryptfs_verbosity > 0))
1244	printk(KERN_INFO "Error attempting to read the [%s] "
1245	"xattr from the lower file; return value = "
1246	"[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1247	rc = -EINVAL;
1248	goto out;
1249	}
1250	out:
1251	return rc;
1252	}
1253
1254	int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1255	struct inode *inode)
1256	{
1257	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1258	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1259	int rc;
1260
1261	rc = ecryptfs_getxattr_lower(lower_dentry: ecryptfs_dentry_to_lower(dentry),
1262	lower_inode: ecryptfs_inode_to_lower(inode),
1263	ECRYPTFS_XATTR_NAME, value: file_size,
1264	ECRYPTFS_SIZE_AND_MARKER_BYTES);
1265	if (rc < 0)
1266	return rc;
1267	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1268	return -EINVAL;
1269	rc = ecryptfs_validate_marker(data: marker);
1270	if (!rc)
1271	ecryptfs_i_size_init(page_virt: file_size, inode);
1272	return rc;
1273	}
1274
1275	/*
1276	* ecryptfs_read_metadata
1277	*
1278	* Common entry point for reading file metadata. From here, we could
1279	* retrieve the header information from the header region of the file,
1280	* the xattr region of the file, or some other repository that is
1281	* stored separately from the file itself. The current implementation
1282	* supports retrieving the metadata information from the file contents
1283	* and from the xattr region.
1284	*
1285	* Returns zero if valid headers found and parsed; non-zero otherwise
1286	*/
1287	int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1288	{
1289	int rc;
1290	char *page_virt;
1291	struct inode *ecryptfs_inode = d_inode(dentry: ecryptfs_dentry);
1292	struct ecryptfs_crypt_stat *crypt_stat =
1293	&ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat;
1294	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1295	&ecryptfs_superblock_to_private(
1296	sb: ecryptfs_dentry->d_sb)->mount_crypt_stat;
1297
1298	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1299	mount_crypt_stat);
1300	/* Read the first page from the underlying file */
1301	page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1302	if (!page_virt) {
1303	rc = -ENOMEM;
1304	goto out;
1305	}
1306	rc = ecryptfs_read_lower(data: page_virt, offset: 0, size: crypt_stat->extent_size,
1307	ecryptfs_inode);
1308	if (rc >= 0)
1309	rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1310	ecryptfs_dentry,
1311	ECRYPTFS_VALIDATE_HEADER_SIZE);
1312	if (rc) {
1313	/* metadata is not in the file header, so try xattrs */
1314	memset(page_virt, 0, PAGE_SIZE);
1315	rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1316	if (rc) {
1317	printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1318	"file header region or xattr region, inode %lu\n",
1319	ecryptfs_inode->i_ino);
1320	rc = -EINVAL;
1321	goto out;
1322	}
1323	rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1324	ecryptfs_dentry,
1325	ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1326	if (rc) {
1327	printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1328	"file xattr region either, inode %lu\n",
1329	ecryptfs_inode->i_ino);
1330	rc = -EINVAL;
1331	}
1332	if (crypt_stat->mount_crypt_stat->flags
1333	& ECRYPTFS_XATTR_METADATA_ENABLED) {
1334	crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1335	} else {
1336	printk(KERN_WARNING "Attempt to access file with "
1337	"crypto metadata only in the extended attribute "
1338	"region, but eCryptfs was mounted without "
1339	"xattr support enabled. eCryptfs will not treat "
1340	"this like an encrypted file, inode %lu\n",
1341	ecryptfs_inode->i_ino);
1342	rc = -EINVAL;
1343	}
1344	}
1345	out:
1346	if (page_virt) {
1347	memset(page_virt, 0, PAGE_SIZE);
1348	kmem_cache_free(s: ecryptfs_header_cache, objp: page_virt);
1349	}
1350	return rc;
1351	}
1352
1353	/*
1354	* ecryptfs_encrypt_filename - encrypt filename
1355	*
1356	* CBC-encrypts the filename. We do not want to encrypt the same
1357	* filename with the same key and IV, which may happen with hard
1358	* links, so we prepend random bits to each filename.
1359	*
1360	* Returns zero on success; non-zero otherwise
1361	*/
1362	static int
1363	ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1364	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1365	{
1366	int rc = 0;
1367
1368	filename->encrypted_filename = NULL;
1369	filename->encrypted_filename_size = 0;
1370	if (mount_crypt_stat && (mount_crypt_stat->flags
1371	& ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1372	size_t packet_size;
1373	size_t remaining_bytes;
1374
1375	rc = ecryptfs_write_tag_70_packet(
1376	NULL, NULL,
1377	packet_size: &filename->encrypted_filename_size,
1378	mount_crypt_stat, NULL,
1379	filename_size: filename->filename_size);
1380	if (rc) {
1381	printk(KERN_ERR "%s: Error attempting to get packet "
1382	"size for tag 72; rc = [%d]\n", __func__,
1383	rc);
1384	filename->encrypted_filename_size = 0;
1385	goto out;
1386	}
1387	filename->encrypted_filename =
1388	kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1389	if (!filename->encrypted_filename) {
1390	rc = -ENOMEM;
1391	goto out;
1392	}
1393	remaining_bytes = filename->encrypted_filename_size;
1394	rc = ecryptfs_write_tag_70_packet(dest: filename->encrypted_filename,
1395	remaining_bytes: &remaining_bytes,
1396	packet_size: &packet_size,
1397	mount_crypt_stat,
1398	filename: filename->filename,
1399	filename_size: filename->filename_size);
1400	if (rc) {
1401	printk(KERN_ERR "%s: Error attempting to generate "
1402	"tag 70 packet; rc = [%d]\n", __func__,
1403	rc);
1404	kfree(objp: filename->encrypted_filename);
1405	filename->encrypted_filename = NULL;
1406	filename->encrypted_filename_size = 0;
1407	goto out;
1408	}
1409	filename->encrypted_filename_size = packet_size;
1410	} else {
1411	printk(KERN_ERR "%s: No support for requested filename "
1412	"encryption method in this release\n", __func__);
1413	rc = -EOPNOTSUPP;
1414	goto out;
1415	}
1416	out:
1417	return rc;
1418	}
1419
1420	static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1421	const char *name, size_t name_size)
1422	{
1423	int rc = 0;
1424
1425	(*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1426	if (!(*copied_name)) {
1427	rc = -ENOMEM;
1428	goto out;
1429	}
1430	memcpy((void *)(*copied_name), (void *)name, name_size);
1431	(*copied_name)[(name_size)] = '\0'; /* Only for convenience
1432	* in printing out the
1433	* string in debug
1434	* messages */
1435	(*copied_name_size) = name_size;
1436	out:
1437	return rc;
1438	}
1439
1440	/**
1441	* ecryptfs_process_key_cipher - Perform key cipher initialization.
1442	* @key_tfm: Crypto context for key material, set by this function
1443	* @cipher_name: Name of the cipher
1444	* @key_size: Size of the key in bytes
1445	*
1446	* Returns zero on success. Any crypto_tfm structs allocated here
1447	* should be released by other functions, such as on a superblock put
1448	* event, regardless of whether this function succeeds for fails.
1449	*/
1450	static int
1451	ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1452	char *cipher_name, size_t *key_size)
1453	{
1454	char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1455	char *full_alg_name = NULL;
1456	int rc;
1457
1458	*key_tfm = NULL;
1459	if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1460	rc = -EINVAL;
1461	printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1462	"allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1463	goto out;
1464	}
1465	rc = ecryptfs_crypto_api_algify_cipher_name(algified_name: &full_alg_name, cipher_name,
1466	chaining_modifier: "ecb");
1467	if (rc)
1468	goto out;
1469	*key_tfm = crypto_alloc_skcipher(alg_name: full_alg_name, type: 0, CRYPTO_ALG_ASYNC);
1470	if (IS_ERR(ptr: *key_tfm)) {
1471	rc = PTR_ERR(ptr: *key_tfm);
1472	printk(KERN_ERR "Unable to allocate crypto cipher with name "
1473	"[%s]; rc = [%d]\n", full_alg_name, rc);
1474	goto out;
1475	}
1476	crypto_skcipher_set_flags(tfm: *key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1477	if (*key_size == 0)
1478	*key_size = crypto_skcipher_max_keysize(tfm: *key_tfm);
1479	get_random_bytes(buf: dummy_key, len: *key_size);
1480	rc = crypto_skcipher_setkey(tfm: *key_tfm, key: dummy_key, keylen: *key_size);
1481	if (rc) {
1482	printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1483	"cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1484	rc);
1485	rc = -EINVAL;
1486	goto out;
1487	}
1488	out:
1489	kfree(objp: full_alg_name);
1490	return rc;
1491	}
1492
1493	struct kmem_cache *ecryptfs_key_tfm_cache;
1494	static struct list_head key_tfm_list;
1495	DEFINE_MUTEX(key_tfm_list_mutex);
1496
1497	int __init ecryptfs_init_crypto(void)
1498	{
1499	INIT_LIST_HEAD(list: &key_tfm_list);
1500	return 0;
1501	}
1502
1503	/**
1504	* ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1505	*
1506	* Called only at module unload time
1507	*/
1508	int ecryptfs_destroy_crypto(void)
1509	{
1510	struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1511
1512	mutex_lock(&key_tfm_list_mutex);
1513	list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1514	key_tfm_list) {
1515	list_del(entry: &key_tfm->key_tfm_list);
1516	crypto_free_skcipher(tfm: key_tfm->key_tfm);
1517	kmem_cache_free(s: ecryptfs_key_tfm_cache, objp: key_tfm);
1518	}
1519	mutex_unlock(lock: &key_tfm_list_mutex);
1520	return 0;
1521	}
1522
1523	int
1524	ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1525	size_t key_size)
1526	{
1527	struct ecryptfs_key_tfm *tmp_tfm;
1528	int rc = 0;
1529
1530	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1531
1532	tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1533	if (key_tfm)
1534	(*key_tfm) = tmp_tfm;
1535	if (!tmp_tfm) {
1536	rc = -ENOMEM;
1537	goto out;
1538	}
1539	mutex_init(&tmp_tfm->key_tfm_mutex);
1540	strscpy(tmp_tfm->cipher_name, cipher_name);
1541	tmp_tfm->key_size = key_size;
1542	rc = ecryptfs_process_key_cipher(key_tfm: &tmp_tfm->key_tfm,
1543	cipher_name: tmp_tfm->cipher_name,
1544	key_size: &tmp_tfm->key_size);
1545	if (rc) {
1546	printk(KERN_ERR "Error attempting to initialize key TFM "
1547	"cipher with name = [%s]; rc = [%d]\n",
1548	tmp_tfm->cipher_name, rc);
1549	kmem_cache_free(s: ecryptfs_key_tfm_cache, objp: tmp_tfm);
1550	if (key_tfm)
1551	(*key_tfm) = NULL;
1552	goto out;
1553	}
1554	list_add(new: &tmp_tfm->key_tfm_list, head: &key_tfm_list);
1555	out:
1556	return rc;
1557	}
1558
1559	/**
1560	* ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1561	* @cipher_name: the name of the cipher to search for
1562	* @key_tfm: set to corresponding tfm if found
1563	*
1564	* Searches for cached key_tfm matching @cipher_name
1565	* Must be called with &key_tfm_list_mutex held
1566	* Returns 1 if found, with @key_tfm set
1567	* Returns 0 if not found, with @key_tfm set to NULL
1568	*/
1569	int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1570	{
1571	struct ecryptfs_key_tfm *tmp_key_tfm;
1572
1573	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1574
1575	list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1576	if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1577	if (key_tfm)
1578	(*key_tfm) = tmp_key_tfm;
1579	return 1;
1580	}
1581	}
1582	if (key_tfm)
1583	(*key_tfm) = NULL;
1584	return 0;
1585	}
1586
1587	/**
1588	* ecryptfs_get_tfm_and_mutex_for_cipher_name
1589	*
1590	* @tfm: set to cached tfm found, or new tfm created
1591	* @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1592	* @cipher_name: the name of the cipher to search for and/or add
1593	*
1594	* Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1595	* Searches for cached item first, and creates new if not found.
1596	* Returns 0 on success, non-zero if adding new cipher failed
1597	*/
1598	int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1599	struct mutex **tfm_mutex,
1600	char *cipher_name)
1601	{
1602	struct ecryptfs_key_tfm *key_tfm;
1603	int rc = 0;
1604
1605	(*tfm) = NULL;
1606	(*tfm_mutex) = NULL;
1607
1608	mutex_lock(&key_tfm_list_mutex);
1609	if (!ecryptfs_tfm_exists(cipher_name, key_tfm: &key_tfm)) {
1610	rc = ecryptfs_add_new_key_tfm(key_tfm: &key_tfm, cipher_name, key_size: 0);
1611	if (rc) {
1612	printk(KERN_ERR "Error adding new key_tfm to list; "
1613	"rc = [%d]\n", rc);
1614	goto out;
1615	}
1616	}
1617	(*tfm) = key_tfm->key_tfm;
1618	(*tfm_mutex) = &key_tfm->key_tfm_mutex;
1619	out:
1620	mutex_unlock(lock: &key_tfm_list_mutex);
1621	return rc;
1622	}
1623
1624	/* 64 characters forming a 6-bit target field */
1625	static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1626	"EFGHIJKLMNOPQRST"
1627	"UVWXYZabcdefghij"
1628	"klmnopqrstuvwxyz");
1629
1630	/* We could either offset on every reverse map or just pad some 0x00's
1631	* at the front here */
1632	static const unsigned char filename_rev_map[256] = {
1633	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1634	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1635	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1636	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1637	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1638	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1639	0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1640	0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1641	0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1642	0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1643	0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1644	0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1645	0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1646	0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1647	0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1648	0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1649	};
1650
1651	/**
1652	* ecryptfs_encode_for_filename
1653	* @dst: Destination location for encoded filename
1654	* @dst_size: Size of the encoded filename in bytes
1655	* @src: Source location for the filename to encode
1656	* @src_size: Size of the source in bytes
1657	*/
1658	static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1659	unsigned char *src, size_t src_size)
1660	{
1661	size_t num_blocks;
1662	size_t block_num = 0;
1663	size_t dst_offset = 0;
1664	unsigned char last_block[3];
1665
1666	if (src_size == 0) {
1667	(*dst_size) = 0;
1668	goto out;
1669	}
1670	num_blocks = (src_size / 3);
1671	if ((src_size % 3) == 0) {
1672	memcpy(last_block, (&src[src_size - 3]), 3);
1673	} else {
1674	num_blocks++;
1675	last_block[2] = 0x00;
1676	switch (src_size % 3) {
1677	case 1:
1678	last_block[0] = src[src_size - 1];
1679	last_block[1] = 0x00;
1680	break;
1681	case 2:
1682	last_block[0] = src[src_size - 2];
1683	last_block[1] = src[src_size - 1];
1684	}
1685	}
1686	(*dst_size) = (num_blocks * 4);
1687	if (!dst)
1688	goto out;
1689	while (block_num < num_blocks) {
1690	unsigned char *src_block;
1691	unsigned char dst_block[4];
1692
1693	if (block_num == (num_blocks - 1))
1694	src_block = last_block;
1695	else
1696	src_block = &src[block_num * 3];
1697	dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1698	dst_block[1] = (((src_block[0] << 4) & 0x30)
1699	| ((src_block[1] >> 4) & 0x0F));
1700	dst_block[2] = (((src_block[1] << 2) & 0x3C)
1701	| ((src_block[2] >> 6) & 0x03));
1702	dst_block[3] = (src_block[2] & 0x3F);
1703	dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1704	dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1705	dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1706	dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1707	block_num++;
1708	}
1709	out:
1710	return;
1711	}
1712
1713	static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1714	{
1715	/* Not exact; conservatively long. Every block of 4
1716	* encoded characters decodes into a block of 3
1717	* decoded characters. This segment of code provides
1718	* the caller with the maximum amount of allocated
1719	* space that @dst will need to point to in a
1720	* subsequent call. */
1721	return ((encoded_size + 1) * 3) / 4;
1722	}
1723
1724	/**
1725	* ecryptfs_decode_from_filename
1726	* @dst: If NULL, this function only sets @dst_size and returns. If
1727	* non-NULL, this function decodes the encoded octets in @src
1728	* into the memory that @dst points to.
1729	* @dst_size: Set to the size of the decoded string.
1730	* @src: The encoded set of octets to decode.
1731	* @src_size: The size of the encoded set of octets to decode.
1732	*/
1733	static void
1734	ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1735	const unsigned char *src, size_t src_size)
1736	{
1737	u8 current_bit_offset = 0;
1738	size_t src_byte_offset = 0;
1739	size_t dst_byte_offset = 0;
1740
1741	if (!dst) {
1742	(*dst_size) = ecryptfs_max_decoded_size(encoded_size: src_size);
1743	goto out;
1744	}
1745	while (src_byte_offset < src_size) {
1746	unsigned char src_byte =
1747	filename_rev_map[(int)src[src_byte_offset]];
1748
1749	switch (current_bit_offset) {
1750	case 0:
1751	dst[dst_byte_offset] = (src_byte << 2);
1752	current_bit_offset = 6;
1753	break;
1754	case 6:
1755	dst[dst_byte_offset++] |= (src_byte >> 4);
1756	dst[dst_byte_offset] = ((src_byte & 0xF)
1757	<< 4);
1758	current_bit_offset = 4;
1759	break;
1760	case 4:
1761	dst[dst_byte_offset++] |= (src_byte >> 2);
1762	dst[dst_byte_offset] = (src_byte << 6);
1763	current_bit_offset = 2;
1764	break;
1765	case 2:
1766	dst[dst_byte_offset++] |= (src_byte);
1767	current_bit_offset = 0;
1768	break;
1769	}
1770	src_byte_offset++;
1771	}
1772	(*dst_size) = dst_byte_offset;
1773	out:
1774	return;
1775	}
1776
1777	/**
1778	* ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1779	* @encoded_name: The encrypted name
1780	* @encoded_name_size: Length of the encrypted name
1781	* @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1782	* @name: The plaintext name
1783	* @name_size: The length of the plaintext name
1784	*
1785	* Encrypts and encodes a filename into something that constitutes a
1786	* valid filename for a filesystem, with printable characters.
1787	*
1788	* We assume that we have a properly initialized crypto context,
1789	* pointed to by crypt_stat->tfm.
1790	*
1791	* Returns zero on success; non-zero on otherwise
1792	*/
1793	int ecryptfs_encrypt_and_encode_filename(
1794	char **encoded_name,
1795	size_t *encoded_name_size,
1796	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1797	const char *name, size_t name_size)
1798	{
1799	size_t encoded_name_no_prefix_size;
1800	int rc = 0;
1801
1802	(*encoded_name) = NULL;
1803	(*encoded_name_size) = 0;
1804	if (mount_crypt_stat && (mount_crypt_stat->flags
1805	& ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1806	struct ecryptfs_filename *filename;
1807
1808	filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1809	if (!filename) {
1810	rc = -ENOMEM;
1811	goto out;
1812	}
1813	filename->filename = (char *)name;
1814	filename->filename_size = name_size;
1815	rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1816	if (rc) {
1817	printk(KERN_ERR "%s: Error attempting to encrypt "
1818	"filename; rc = [%d]\n", __func__, rc);
1819	kfree(objp: filename);
1820	goto out;
1821	}
1822	ecryptfs_encode_for_filename(
1823	NULL, dst_size: &encoded_name_no_prefix_size,
1824	src: filename->encrypted_filename,
1825	src_size: filename->encrypted_filename_size);
1826	if (mount_crypt_stat
1827	&& (mount_crypt_stat->flags
1828	& ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1829	(*encoded_name_size) =
1830	(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1831	+ encoded_name_no_prefix_size);
1832	else
1833	(*encoded_name_size) =
1834	(ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1835	+ encoded_name_no_prefix_size);
1836	(*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1837	if (!(*encoded_name)) {
1838	rc = -ENOMEM;
1839	kfree(objp: filename->encrypted_filename);
1840	kfree(objp: filename);
1841	goto out;
1842	}
1843	if (mount_crypt_stat
1844	&& (mount_crypt_stat->flags
1845	& ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1846	memcpy((*encoded_name),
1847	ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1848	ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1849	ecryptfs_encode_for_filename(
1850	dst: ((*encoded_name)
1851	+ ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1852	dst_size: &encoded_name_no_prefix_size,
1853	src: filename->encrypted_filename,
1854	src_size: filename->encrypted_filename_size);
1855	(*encoded_name_size) =
1856	(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1857	+ encoded_name_no_prefix_size);
1858	(*encoded_name)[(*encoded_name_size)] = '\0';
1859	} else {
1860	rc = -EOPNOTSUPP;
1861	}
1862	if (rc) {
1863	printk(KERN_ERR "%s: Error attempting to encode "
1864	"encrypted filename; rc = [%d]\n", __func__,
1865	rc);
1866	kfree(objp: (*encoded_name));
1867	(*encoded_name) = NULL;
1868	(*encoded_name_size) = 0;
1869	}
1870	kfree(objp: filename->encrypted_filename);
1871	kfree(objp: filename);
1872	} else {
1873	rc = ecryptfs_copy_filename(copied_name: encoded_name,
1874	copied_name_size: encoded_name_size,
1875	name, name_size);
1876	}
1877	out:
1878	return rc;
1879	}
1880
1881	/**
1882	* ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1883	* @plaintext_name: The plaintext name
1884	* @plaintext_name_size: The plaintext name size
1885	* @sb: Ecryptfs's super_block
1886	* @name: The filename in cipher text
1887	* @name_size: The cipher text name size
1888	*
1889	* Decrypts and decodes the filename.
1890	*
1891	* Returns zero on error; non-zero otherwise
1892	*/
1893	int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
1894	size_t *plaintext_name_size,
1895	struct super_block *sb,
1896	const char *name, size_t name_size)
1897	{
1898	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1899	&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
1900	char *decoded_name;
1901	size_t decoded_name_size;
1902	size_t packet_size;
1903	int rc = 0;
1904
1905	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
1906	!(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
1907	if (is_dot_dotdot(name, len: name_size)) {
1908	rc = ecryptfs_copy_filename(copied_name: plaintext_name,
1909	copied_name_size: plaintext_name_size,
1910	name, name_size);
1911	goto out;
1912	}
1913
1914	if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
1915	strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1916	ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
1917	rc = -EINVAL;
1918	goto out;
1919	}
1920
1921	name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1922	name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1923	ecryptfs_decode_from_filename(NULL, dst_size: &decoded_name_size,
1924	src: name, src_size: name_size);
1925	decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
1926	if (!decoded_name) {
1927	rc = -ENOMEM;
1928	goto out;
1929	}
1930	ecryptfs_decode_from_filename(dst: decoded_name, dst_size: &decoded_name_size,
1931	src: name, src_size: name_size);
1932	rc = ecryptfs_parse_tag_70_packet(filename: plaintext_name,
1933	filename_size: plaintext_name_size,
1934	packet_size: &packet_size,
1935	mount_crypt_stat,
1936	data: decoded_name,
1937	max_packet_size: decoded_name_size);
1938	if (rc) {
1939	ecryptfs_printk(KERN_DEBUG,
1940	"%s: Could not parse tag 70 packet from filename\n",
1941	__func__);
1942	goto out_free;
1943	}
1944	} else {
1945	rc = ecryptfs_copy_filename(copied_name: plaintext_name,
1946	copied_name_size: plaintext_name_size,
1947	name, name_size);
1948	goto out;
1949	}
1950	out_free:
1951	kfree(objp: decoded_name);
1952	out:
1953	return rc;
1954	}
1955
1956	#define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143
1957
1958	int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
1959	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1960	{
1961	struct crypto_skcipher *tfm;
1962	struct mutex *tfm_mutex;
1963	size_t cipher_blocksize;
1964	int rc;
1965
1966	if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1967	(*namelen) = lower_namelen;
1968	return 0;
1969	}
1970
1971	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(tfm: &tfm, tfm_mutex: &tfm_mutex,
1972	cipher_name: mount_crypt_stat->global_default_fn_cipher_name);
1973	if (unlikely(rc)) {
1974	(*namelen) = 0;
1975	return rc;
1976	}
1977
1978	mutex_lock(tfm_mutex);
1979	cipher_blocksize = crypto_skcipher_blocksize(tfm);
1980	mutex_unlock(lock: tfm_mutex);
1981
1982	/* Return an exact amount for the common cases */
1983	if (lower_namelen == NAME_MAX
1984	&& (cipher_blocksize == 8 || cipher_blocksize == 16)) {
1985	(*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
1986	return 0;
1987	}
1988
1989	/* Return a safe estimate for the uncommon cases */
1990	(*namelen) = lower_namelen;
1991	(*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1992	/* Since this is the max decoded size, subtract 1 "decoded block" len */
1993	(*namelen) = ecryptfs_max_decoded_size(encoded_size: *namelen) - 3;
1994	(*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
1995	(*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
1996	/* Worst case is that the filename is padded nearly a full block size */
1997	(*namelen) -= cipher_blocksize - 1;
1998
1999	if ((*namelen) < 0)
2000	(*namelen) = 0;
2001
2002	return 0;
2003	}
2004