Linux Audio

Check our new training course

Linux debugging, profiling, tracing and performance analysis training

Apr 14-17, 2025
Register
Loading...
   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/hash.h>
  13#include <crypto/skcipher.h>
  14#include <linux/fs.h>
  15#include <linux/mount.h>
  16#include <linux/pagemap.h>
  17#include <linux/random.h>
  18#include <linux/compiler.h>
  19#include <linux/key.h>
  20#include <linux/namei.h>
  21#include <linux/file.h>
  22#include <linux/scatterlist.h>
  23#include <linux/slab.h>
  24#include <linux/unaligned.h>
  25#include <linux/kernel.h>
  26#include <linux/xattr.h>
  27#include "ecryptfs_kernel.h"
  28
  29#define DECRYPT		0
  30#define ENCRYPT		1
  31
  32/**
  33 * ecryptfs_from_hex
  34 * @dst: Buffer to take the bytes from src hex; must be at least of
  35 *       size (src_size / 2)
  36 * @src: Buffer to be converted from a hex string representation to raw value
  37 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  38 */
  39void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  40{
  41	int x;
  42	char tmp[3] = { 0, };
  43
  44	for (x = 0; x < dst_size; x++) {
  45		tmp[0] = src[x * 2];
  46		tmp[1] = src[x * 2 + 1];
  47		dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  48	}
  49}
  50
  51/**
  52 * ecryptfs_calculate_md5 - calculates the md5 of @src
  53 * @dst: Pointer to 16 bytes of allocated memory
  54 * @crypt_stat: Pointer to crypt_stat struct for the current inode
  55 * @src: Data to be md5'd
  56 * @len: Length of @src
  57 *
  58 * Uses the allocated crypto context that crypt_stat references to
  59 * generate the MD5 sum of the contents of src.
  60 */
  61static int ecryptfs_calculate_md5(char *dst,
  62				  struct ecryptfs_crypt_stat *crypt_stat,
  63				  char *src, int len)
  64{
  65	int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst);
  66
  67	if (rc) {
  68		printk(KERN_ERR
  69		       "%s: Error computing crypto hash; rc = [%d]\n",
  70		       __func__, rc);
  71		goto out;
  72	}
  73out:
  74	return rc;
  75}
  76
  77static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
  78						  char *cipher_name,
  79						  char *chaining_modifier)
  80{
  81	int cipher_name_len = strlen(cipher_name);
  82	int chaining_modifier_len = strlen(chaining_modifier);
  83	int algified_name_len;
  84	int rc;
  85
  86	algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
  87	(*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
  88	if (!(*algified_name)) {
  89		rc = -ENOMEM;
  90		goto out;
  91	}
  92	snprintf((*algified_name), algified_name_len, "%s(%s)",
  93		 chaining_modifier, cipher_name);
  94	rc = 0;
  95out:
  96	return rc;
  97}
  98
  99/**
 100 * ecryptfs_derive_iv
 101 * @iv: destination for the derived iv vale
 102 * @crypt_stat: Pointer to crypt_stat struct for the current inode
 103 * @offset: Offset of the extent whose IV we are to derive
 104 *
 105 * Generate the initialization vector from the given root IV and page
 106 * offset.
 107 *
 108 * Returns zero on success; non-zero on error.
 109 */
 110int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 111		       loff_t offset)
 112{
 113	int rc = 0;
 114	char dst[MD5_DIGEST_SIZE];
 115	char src[ECRYPTFS_MAX_IV_BYTES + 16];
 116
 117	if (unlikely(ecryptfs_verbosity > 0)) {
 118		ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 119		ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 120	}
 121	/* TODO: It is probably secure to just cast the least
 122	 * significant bits of the root IV into an unsigned long and
 123	 * add the offset to that rather than go through all this
 124	 * hashing business. -Halcrow */
 125	memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 126	memset((src + crypt_stat->iv_bytes), 0, 16);
 127	snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
 128	if (unlikely(ecryptfs_verbosity > 0)) {
 129		ecryptfs_printk(KERN_DEBUG, "source:\n");
 130		ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 131	}
 132	rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 133				    (crypt_stat->iv_bytes + 16));
 134	if (rc) {
 135		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 136				"MD5 while generating IV for a page\n");
 137		goto out;
 138	}
 139	memcpy(iv, dst, crypt_stat->iv_bytes);
 140	if (unlikely(ecryptfs_verbosity > 0)) {
 141		ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 142		ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 143	}
 144out:
 145	return rc;
 146}
 147
 148/**
 149 * ecryptfs_init_crypt_stat
 150 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 151 *
 152 * Initialize the crypt_stat structure.
 153 */
 154int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 155{
 156	struct crypto_shash *tfm;
 157	int rc;
 158
 159	tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
 160	if (IS_ERR(tfm)) {
 161		rc = PTR_ERR(tfm);
 162		ecryptfs_printk(KERN_ERR, "Error attempting to "
 163				"allocate crypto context; rc = [%d]\n",
 164				rc);
 165		return rc;
 166	}
 167
 168	memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 169	INIT_LIST_HEAD(&crypt_stat->keysig_list);
 170	mutex_init(&crypt_stat->keysig_list_mutex);
 171	mutex_init(&crypt_stat->cs_mutex);
 172	mutex_init(&crypt_stat->cs_tfm_mutex);
 173	crypt_stat->hash_tfm = tfm;
 174	crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 175
 176	return 0;
 177}
 178
 179/**
 180 * ecryptfs_destroy_crypt_stat
 181 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 182 *
 183 * Releases all memory associated with a crypt_stat struct.
 184 */
 185void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 186{
 187	struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 188
 189	crypto_free_skcipher(crypt_stat->tfm);
 190	crypto_free_shash(crypt_stat->hash_tfm);
 191	list_for_each_entry_safe(key_sig, key_sig_tmp,
 192				 &crypt_stat->keysig_list, crypt_stat_list) {
 193		list_del(&key_sig->crypt_stat_list);
 194		kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 195	}
 196	memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 197}
 198
 199void ecryptfs_destroy_mount_crypt_stat(
 200	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 201{
 202	struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 203
 204	if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 205		return;
 206	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 207	list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 208				 &mount_crypt_stat->global_auth_tok_list,
 209				 mount_crypt_stat_list) {
 210		list_del(&auth_tok->mount_crypt_stat_list);
 211		if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 212			key_put(auth_tok->global_auth_tok_key);
 213		kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 214	}
 215	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 216	memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 217}
 218
 219/**
 220 * virt_to_scatterlist
 221 * @addr: Virtual address
 222 * @size: Size of data; should be an even multiple of the block size
 223 * @sg: Pointer to scatterlist array; set to NULL to obtain only
 224 *      the number of scatterlist structs required in array
 225 * @sg_size: Max array size
 226 *
 227 * Fills in a scatterlist array with page references for a passed
 228 * virtual address.
 229 *
 230 * Returns the number of scatterlist structs in array used
 231 */
 232int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 233			int sg_size)
 234{
 235	int i = 0;
 236	struct page *pg;
 237	int offset;
 238	int remainder_of_page;
 239
 240	sg_init_table(sg, sg_size);
 241
 242	while (size > 0 && i < sg_size) {
 243		pg = virt_to_page(addr);
 244		offset = offset_in_page(addr);
 245		sg_set_page(&sg[i], pg, 0, offset);
 246		remainder_of_page = PAGE_SIZE - offset;
 247		if (size >= remainder_of_page) {
 248			sg[i].length = remainder_of_page;
 249			addr += remainder_of_page;
 250			size -= remainder_of_page;
 251		} else {
 252			sg[i].length = size;
 253			addr += size;
 254			size = 0;
 255		}
 256		i++;
 257	}
 258	if (size > 0)
 259		return -ENOMEM;
 260	return i;
 261}
 262
 263/**
 264 * crypt_scatterlist
 265 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 266 * @dst_sg: Destination of the data after performing the crypto operation
 267 * @src_sg: Data to be encrypted or decrypted
 268 * @size: Length of data
 269 * @iv: IV to use
 270 * @op: ENCRYPT or DECRYPT to indicate the desired operation
 271 *
 272 * Returns the number of bytes encrypted or decrypted; negative value on error
 273 */
 274static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 275			     struct scatterlist *dst_sg,
 276			     struct scatterlist *src_sg, int size,
 277			     unsigned char *iv, int op)
 278{
 279	struct skcipher_request *req = NULL;
 280	DECLARE_CRYPTO_WAIT(ecr);
 281	int rc = 0;
 282
 283	if (unlikely(ecryptfs_verbosity > 0)) {
 284		ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 285				crypt_stat->key_size);
 286		ecryptfs_dump_hex(crypt_stat->key,
 287				  crypt_stat->key_size);
 288	}
 289
 290	mutex_lock(&crypt_stat->cs_tfm_mutex);
 291	req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
 292	if (!req) {
 293		mutex_unlock(&crypt_stat->cs_tfm_mutex);
 294		rc = -ENOMEM;
 295		goto out;
 296	}
 297
 298	skcipher_request_set_callback(req,
 299			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 300			crypto_req_done, &ecr);
 301	/* Consider doing this once, when the file is opened */
 302	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 303		rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 304					    crypt_stat->key_size);
 305		if (rc) {
 306			ecryptfs_printk(KERN_ERR,
 307					"Error setting key; rc = [%d]\n",
 308					rc);
 309			mutex_unlock(&crypt_stat->cs_tfm_mutex);
 310			rc = -EINVAL;
 311			goto out;
 312		}
 313		crypt_stat->flags |= ECRYPTFS_KEY_SET;
 314	}
 315	mutex_unlock(&crypt_stat->cs_tfm_mutex);
 316	skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 317	rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
 318			     crypto_skcipher_decrypt(req);
 319	rc = crypto_wait_req(rc, &ecr);
 320out:
 321	skcipher_request_free(req);
 322	return rc;
 323}
 324
 325/*
 326 * lower_offset_for_page
 327 *
 328 * Convert an eCryptfs page index into a lower byte offset
 329 */
 330static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 331				    struct folio *folio)
 332{
 333	return ecryptfs_lower_header_size(crypt_stat) +
 334	       (loff_t)folio->index * PAGE_SIZE;
 335}
 336
 337/**
 338 * crypt_extent
 339 * @crypt_stat: crypt_stat containing cryptographic context for the
 340 *              encryption operation
 341 * @dst_page: The page to write the result into
 342 * @src_page: The page to read from
 343 * @page_index: The offset in the file (in units of PAGE_SIZE)
 344 * @extent_offset: Page extent offset for use in generating IV
 345 * @op: ENCRYPT or DECRYPT to indicate the desired operation
 346 *
 347 * Encrypts or decrypts one extent of data.
 348 *
 349 * Return zero on success; non-zero otherwise
 350 */
 351static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 352			struct page *dst_page,
 353			struct page *src_page,
 354			pgoff_t page_index,
 355			unsigned long extent_offset, int op)
 356{
 357	loff_t extent_base;
 358	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 359	struct scatterlist src_sg, dst_sg;
 360	size_t extent_size = crypt_stat->extent_size;
 361	int rc;
 362
 363	extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
 364	rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 365				(extent_base + extent_offset));
 366	if (rc) {
 367		ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 368			"extent [0x%.16llx]; rc = [%d]\n",
 369			(unsigned long long)(extent_base + extent_offset), rc);
 370		goto out;
 371	}
 372
 373	sg_init_table(&src_sg, 1);
 374	sg_init_table(&dst_sg, 1);
 375
 376	sg_set_page(&src_sg, src_page, extent_size,
 377		    extent_offset * extent_size);
 378	sg_set_page(&dst_sg, dst_page, extent_size,
 379		    extent_offset * extent_size);
 380
 381	rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 382			       extent_iv, op);
 383	if (rc < 0) {
 384		printk(KERN_ERR "%s: Error attempting to crypt page with "
 385		       "page_index = [%ld], extent_offset = [%ld]; "
 386		       "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 387		goto out;
 388	}
 389	rc = 0;
 390out:
 391	return rc;
 392}
 393
 394/**
 395 * ecryptfs_encrypt_page
 396 * @folio: Folio mapped from the eCryptfs inode for the file; contains
 397 *        decrypted content that needs to be encrypted (to a temporary
 398 *        page; not in place) and written out to the lower file
 399 *
 400 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 401 * that eCryptfs pages may straddle the lower pages -- for instance,
 402 * if the file was created on a machine with an 8K page size
 403 * (resulting in an 8K header), and then the file is copied onto a
 404 * host with a 32K page size, then when reading page 0 of the eCryptfs
 405 * file, 24K of page 0 of the lower file will be read and decrypted,
 406 * and then 8K of page 1 of the lower file will be read and decrypted.
 407 *
 408 * Returns zero on success; negative on error
 409 */
 410int ecryptfs_encrypt_page(struct folio *folio)
 411{
 412	struct inode *ecryptfs_inode;
 413	struct ecryptfs_crypt_stat *crypt_stat;
 414	char *enc_extent_virt;
 415	struct page *enc_extent_page = NULL;
 416	loff_t extent_offset;
 417	loff_t lower_offset;
 418	int rc = 0;
 419
 420	ecryptfs_inode = folio->mapping->host;
 421	crypt_stat =
 422		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 423	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 424	enc_extent_page = alloc_page(GFP_USER);
 425	if (!enc_extent_page) {
 426		rc = -ENOMEM;
 427		ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 428				"encrypted extent\n");
 429		goto out;
 430	}
 431
 432	for (extent_offset = 0;
 433	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 434	     extent_offset++) {
 435		rc = crypt_extent(crypt_stat, enc_extent_page,
 436				folio_page(folio, 0), folio->index,
 437				extent_offset, ENCRYPT);
 438		if (rc) {
 439			printk(KERN_ERR "%s: Error encrypting extent; "
 440			       "rc = [%d]\n", __func__, rc);
 441			goto out;
 442		}
 443	}
 444
 445	lower_offset = lower_offset_for_page(crypt_stat, folio);
 446	enc_extent_virt = kmap_local_page(enc_extent_page);
 447	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 448				  PAGE_SIZE);
 449	kunmap_local(enc_extent_virt);
 450	if (rc < 0) {
 451		ecryptfs_printk(KERN_ERR,
 452			"Error attempting to write lower page; rc = [%d]\n",
 453			rc);
 454		goto out;
 455	}
 456	rc = 0;
 457out:
 458	if (enc_extent_page) {
 459		__free_page(enc_extent_page);
 460	}
 461	return rc;
 462}
 463
 464/**
 465 * ecryptfs_decrypt_page
 466 * @folio: Folio mapped from the eCryptfs inode for the file; data read
 467 *        and decrypted from the lower file will be written into this
 468 *        page
 469 *
 470 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 471 * that eCryptfs pages may straddle the lower pages -- for instance,
 472 * if the file was created on a machine with an 8K page size
 473 * (resulting in an 8K header), and then the file is copied onto a
 474 * host with a 32K page size, then when reading page 0 of the eCryptfs
 475 * file, 24K of page 0 of the lower file will be read and decrypted,
 476 * and then 8K of page 1 of the lower file will be read and decrypted.
 477 *
 478 * Returns zero on success; negative on error
 479 */
 480int ecryptfs_decrypt_page(struct folio *folio)
 481{
 482	struct inode *ecryptfs_inode;
 483	struct ecryptfs_crypt_stat *crypt_stat;
 484	char *page_virt;
 485	unsigned long extent_offset;
 486	loff_t lower_offset;
 487	int rc = 0;
 488
 489	ecryptfs_inode = folio->mapping->host;
 490	crypt_stat =
 491		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 492	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 493
 494	lower_offset = lower_offset_for_page(crypt_stat, folio);
 495	page_virt = kmap_local_folio(folio, 0);
 496	rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
 497				 ecryptfs_inode);
 498	kunmap_local(page_virt);
 499	if (rc < 0) {
 500		ecryptfs_printk(KERN_ERR,
 501			"Error attempting to read lower page; rc = [%d]\n",
 502			rc);
 503		goto out;
 504	}
 505
 506	for (extent_offset = 0;
 507	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 508	     extent_offset++) {
 509		struct page *page = folio_page(folio, 0);
 510		rc = crypt_extent(crypt_stat, page, page, folio->index,
 511				extent_offset, DECRYPT);
 512		if (rc) {
 513			printk(KERN_ERR "%s: Error decrypting extent; "
 514			       "rc = [%d]\n", __func__, rc);
 515			goto out;
 516		}
 517	}
 518out:
 519	return rc;
 520}
 521
 522#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 523
 524/**
 525 * ecryptfs_init_crypt_ctx
 526 * @crypt_stat: Uninitialized crypt stats structure
 527 *
 528 * Initialize the crypto context.
 529 *
 530 * TODO: Performance: Keep a cache of initialized cipher contexts;
 531 * only init if needed
 532 */
 533int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 534{
 535	char *full_alg_name;
 536	int rc = -EINVAL;
 537
 538	ecryptfs_printk(KERN_DEBUG,
 539			"Initializing cipher [%s]; strlen = [%d]; "
 540			"key_size_bits = [%zd]\n",
 541			crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 542			crypt_stat->key_size << 3);
 543	mutex_lock(&crypt_stat->cs_tfm_mutex);
 544	if (crypt_stat->tfm) {
 545		rc = 0;
 546		goto out_unlock;
 547	}
 548	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 549						    crypt_stat->cipher, "cbc");
 550	if (rc)
 551		goto out_unlock;
 552	crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
 553	if (IS_ERR(crypt_stat->tfm)) {
 554		rc = PTR_ERR(crypt_stat->tfm);
 555		crypt_stat->tfm = NULL;
 556		ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 557				"Error initializing cipher [%s]\n",
 558				full_alg_name);
 559		goto out_free;
 560	}
 561	crypto_skcipher_set_flags(crypt_stat->tfm,
 562				  CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
 563	rc = 0;
 564out_free:
 565	kfree(full_alg_name);
 566out_unlock:
 567	mutex_unlock(&crypt_stat->cs_tfm_mutex);
 568	return rc;
 569}
 570
 571static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 572{
 573	int extent_size_tmp;
 574
 575	crypt_stat->extent_mask = 0xFFFFFFFF;
 576	crypt_stat->extent_shift = 0;
 577	if (crypt_stat->extent_size == 0)
 578		return;
 579	extent_size_tmp = crypt_stat->extent_size;
 580	while ((extent_size_tmp & 0x01) == 0) {
 581		extent_size_tmp >>= 1;
 582		crypt_stat->extent_mask <<= 1;
 583		crypt_stat->extent_shift++;
 584	}
 585}
 586
 587void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 588{
 589	/* Default values; may be overwritten as we are parsing the
 590	 * packets. */
 591	crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 592	set_extent_mask_and_shift(crypt_stat);
 593	crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 594	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 595		crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 596	else {
 597		if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 598			crypt_stat->metadata_size =
 599				ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 600		else
 601			crypt_stat->metadata_size = PAGE_SIZE;
 602	}
 603}
 604
 605/*
 606 * ecryptfs_compute_root_iv
 607 *
 608 * On error, sets the root IV to all 0's.
 609 */
 610int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 611{
 612	int rc = 0;
 613	char dst[MD5_DIGEST_SIZE];
 614
 615	BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 616	BUG_ON(crypt_stat->iv_bytes <= 0);
 617	if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 618		rc = -EINVAL;
 619		ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 620				"cannot generate root IV\n");
 621		goto out;
 622	}
 623	rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 624				    crypt_stat->key_size);
 625	if (rc) {
 626		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 627				"MD5 while generating root IV\n");
 628		goto out;
 629	}
 630	memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 631out:
 632	if (rc) {
 633		memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 634		crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 635	}
 636	return rc;
 637}
 638
 639static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 640{
 641	get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 642	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 643	ecryptfs_compute_root_iv(crypt_stat);
 644	if (unlikely(ecryptfs_verbosity > 0)) {
 645		ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 646		ecryptfs_dump_hex(crypt_stat->key,
 647				  crypt_stat->key_size);
 648	}
 649}
 650
 651/**
 652 * ecryptfs_copy_mount_wide_flags_to_inode_flags
 653 * @crypt_stat: The inode's cryptographic context
 654 * @mount_crypt_stat: The mount point's cryptographic context
 655 *
 656 * This function propagates the mount-wide flags to individual inode
 657 * flags.
 658 */
 659static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 660	struct ecryptfs_crypt_stat *crypt_stat,
 661	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 662{
 663	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 664		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 665	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 666		crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 667	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 668		crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 669		if (mount_crypt_stat->flags
 670		    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 671			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 672		else if (mount_crypt_stat->flags
 673			 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 674			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 675	}
 676}
 677
 678static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 679	struct ecryptfs_crypt_stat *crypt_stat,
 680	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 681{
 682	struct ecryptfs_global_auth_tok *global_auth_tok;
 683	int rc = 0;
 684
 685	mutex_lock(&crypt_stat->keysig_list_mutex);
 686	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 687
 688	list_for_each_entry(global_auth_tok,
 689			    &mount_crypt_stat->global_auth_tok_list,
 690			    mount_crypt_stat_list) {
 691		if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 692			continue;
 693		rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 694		if (rc) {
 695			printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 696			goto out;
 697		}
 698	}
 699
 700out:
 701	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 702	mutex_unlock(&crypt_stat->keysig_list_mutex);
 703	return rc;
 704}
 705
 706/**
 707 * ecryptfs_set_default_crypt_stat_vals
 708 * @crypt_stat: The inode's cryptographic context
 709 * @mount_crypt_stat: The mount point's cryptographic context
 710 *
 711 * Default values in the event that policy does not override them.
 712 */
 713static void ecryptfs_set_default_crypt_stat_vals(
 714	struct ecryptfs_crypt_stat *crypt_stat,
 715	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 716{
 717	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 718						      mount_crypt_stat);
 719	ecryptfs_set_default_sizes(crypt_stat);
 720	strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 721	crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 722	crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 723	crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 724	crypt_stat->mount_crypt_stat = mount_crypt_stat;
 725}
 726
 727/**
 728 * ecryptfs_new_file_context
 729 * @ecryptfs_inode: The eCryptfs inode
 730 *
 731 * If the crypto context for the file has not yet been established,
 732 * this is where we do that.  Establishing a new crypto context
 733 * involves the following decisions:
 734 *  - What cipher to use?
 735 *  - What set of authentication tokens to use?
 736 * Here we just worry about getting enough information into the
 737 * authentication tokens so that we know that they are available.
 738 * We associate the available authentication tokens with the new file
 739 * via the set of signatures in the crypt_stat struct.  Later, when
 740 * the headers are actually written out, we may again defer to
 741 * userspace to perform the encryption of the session key; for the
 742 * foreseeable future, this will be the case with public key packets.
 743 *
 744 * Returns zero on success; non-zero otherwise
 745 */
 746int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 747{
 748	struct ecryptfs_crypt_stat *crypt_stat =
 749	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 750	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 751	    &ecryptfs_superblock_to_private(
 752		    ecryptfs_inode->i_sb)->mount_crypt_stat;
 753	int cipher_name_len;
 754	int rc = 0;
 755
 756	ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 757	crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 758	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 759						      mount_crypt_stat);
 760	rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 761							 mount_crypt_stat);
 762	if (rc) {
 763		printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 764		       "to the inode key sigs; rc = [%d]\n", rc);
 765		goto out;
 766	}
 767	cipher_name_len =
 768		strlen(mount_crypt_stat->global_default_cipher_name);
 769	memcpy(crypt_stat->cipher,
 770	       mount_crypt_stat->global_default_cipher_name,
 771	       cipher_name_len);
 772	crypt_stat->cipher[cipher_name_len] = '\0';
 773	crypt_stat->key_size =
 774		mount_crypt_stat->global_default_cipher_key_size;
 775	ecryptfs_generate_new_key(crypt_stat);
 776	rc = ecryptfs_init_crypt_ctx(crypt_stat);
 777	if (rc)
 778		ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 779				"context for cipher [%s]: rc = [%d]\n",
 780				crypt_stat->cipher, rc);
 781out:
 782	return rc;
 783}
 784
 785/**
 786 * ecryptfs_validate_marker - check for the ecryptfs marker
 787 * @data: The data block in which to check
 788 *
 789 * Returns zero if marker found; -EINVAL if not found
 790 */
 791static int ecryptfs_validate_marker(char *data)
 792{
 793	u32 m_1, m_2;
 794
 795	m_1 = get_unaligned_be32(data);
 796	m_2 = get_unaligned_be32(data + 4);
 797	if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 798		return 0;
 799	ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
 800			"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
 801			MAGIC_ECRYPTFS_MARKER);
 802	ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
 803			"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
 804	return -EINVAL;
 805}
 806
 807struct ecryptfs_flag_map_elem {
 808	u32 file_flag;
 809	u32 local_flag;
 810};
 811
 812/* Add support for additional flags by adding elements here. */
 813static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 814	{0x00000001, ECRYPTFS_ENABLE_HMAC},
 815	{0x00000002, ECRYPTFS_ENCRYPTED},
 816	{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
 817	{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 818};
 819
 820/**
 821 * ecryptfs_process_flags
 822 * @crypt_stat: The cryptographic context
 823 * @page_virt: Source data to be parsed
 824 * @bytes_read: Updated with the number of bytes read
 825 */
 826static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
 827				  char *page_virt, int *bytes_read)
 828{
 829	int i;
 830	u32 flags;
 831
 832	flags = get_unaligned_be32(page_virt);
 833	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
 834		if (flags & ecryptfs_flag_map[i].file_flag) {
 835			crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
 836		} else
 837			crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
 838	/* Version is in top 8 bits of the 32-bit flag vector */
 839	crypt_stat->file_version = ((flags >> 24) & 0xFF);
 840	(*bytes_read) = 4;
 841}
 842
 843/**
 844 * write_ecryptfs_marker
 845 * @page_virt: The pointer to in a page to begin writing the marker
 846 * @written: Number of bytes written
 847 *
 848 * Marker = 0x3c81b7f5
 849 */
 850static void write_ecryptfs_marker(char *page_virt, size_t *written)
 851{
 852	u32 m_1, m_2;
 853
 854	get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 855	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 856	put_unaligned_be32(m_1, page_virt);
 857	page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 858	put_unaligned_be32(m_2, page_virt);
 859	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 860}
 861
 862void ecryptfs_write_crypt_stat_flags(char *page_virt,
 863				     struct ecryptfs_crypt_stat *crypt_stat,
 864				     size_t *written)
 865{
 866	u32 flags = 0;
 867	int i;
 868
 869	for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
 870		if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
 871			flags |= ecryptfs_flag_map[i].file_flag;
 872	/* Version is in top 8 bits of the 32-bit flag vector */
 873	flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
 874	put_unaligned_be32(flags, page_virt);
 875	(*written) = 4;
 876}
 877
 878struct ecryptfs_cipher_code_str_map_elem {
 879	char cipher_str[16];
 880	u8 cipher_code;
 881};
 882
 883/* Add support for additional ciphers by adding elements here. The
 884 * cipher_code is whatever OpenPGP applications use to identify the
 885 * ciphers. List in order of probability. */
 886static struct ecryptfs_cipher_code_str_map_elem
 887ecryptfs_cipher_code_str_map[] = {
 888	{"aes",RFC2440_CIPHER_AES_128 },
 889	{"blowfish", RFC2440_CIPHER_BLOWFISH},
 890	{"des3_ede", RFC2440_CIPHER_DES3_EDE},
 891	{"cast5", RFC2440_CIPHER_CAST_5},
 892	{"twofish", RFC2440_CIPHER_TWOFISH},
 893	{"cast6", RFC2440_CIPHER_CAST_6},
 894	{"aes", RFC2440_CIPHER_AES_192},
 895	{"aes", RFC2440_CIPHER_AES_256}
 896};
 897
 898/**
 899 * ecryptfs_code_for_cipher_string
 900 * @cipher_name: The string alias for the cipher
 901 * @key_bytes: Length of key in bytes; used for AES code selection
 902 *
 903 * Returns zero on no match, or the cipher code on match
 904 */
 905u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 906{
 907	int i;
 908	u8 code = 0;
 909	struct ecryptfs_cipher_code_str_map_elem *map =
 910		ecryptfs_cipher_code_str_map;
 911
 912	if (strcmp(cipher_name, "aes") == 0) {
 913		switch (key_bytes) {
 914		case 16:
 915			code = RFC2440_CIPHER_AES_128;
 916			break;
 917		case 24:
 918			code = RFC2440_CIPHER_AES_192;
 919			break;
 920		case 32:
 921			code = RFC2440_CIPHER_AES_256;
 922		}
 923	} else {
 924		for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
 925			if (strcmp(cipher_name, map[i].cipher_str) == 0) {
 926				code = map[i].cipher_code;
 927				break;
 928			}
 929	}
 930	return code;
 931}
 932
 933/**
 934 * ecryptfs_cipher_code_to_string
 935 * @str: Destination to write out the cipher name
 936 * @cipher_code: The code to convert to cipher name string
 937 *
 938 * Returns zero on success
 939 */
 940int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
 941{
 942	int rc = 0;
 943	int i;
 944
 945	str[0] = '\0';
 946	for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
 947		if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
 948			strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
 949	if (str[0] == '\0') {
 950		ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
 951				"[%d]\n", cipher_code);
 952		rc = -EINVAL;
 953	}
 954	return rc;
 955}
 956
 957int ecryptfs_read_and_validate_header_region(struct inode *inode)
 958{
 959	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
 960	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
 961	int rc;
 962
 963	rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
 964				 inode);
 965	if (rc < 0)
 966		return rc;
 967	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
 968		return -EINVAL;
 969	rc = ecryptfs_validate_marker(marker);
 970	if (!rc)
 971		ecryptfs_i_size_init(file_size, inode);
 972	return rc;
 973}
 974
 975void
 976ecryptfs_write_header_metadata(char *virt,
 977			       struct ecryptfs_crypt_stat *crypt_stat,
 978			       size_t *written)
 979{
 980	u32 header_extent_size;
 981	u16 num_header_extents_at_front;
 982
 983	header_extent_size = (u32)crypt_stat->extent_size;
 984	num_header_extents_at_front =
 985		(u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
 986	put_unaligned_be32(header_extent_size, virt);
 987	virt += 4;
 988	put_unaligned_be16(num_header_extents_at_front, virt);
 989	(*written) = 6;
 990}
 991
 992struct kmem_cache *ecryptfs_header_cache;
 993
 994/**
 995 * ecryptfs_write_headers_virt
 996 * @page_virt: The virtual address to write the headers to
 997 * @max: The size of memory allocated at page_virt
 998 * @size: Set to the number of bytes written by this function
 999 * @crypt_stat: The cryptographic context
1000 * @ecryptfs_dentry: The eCryptfs dentry
1001 *
1002 * Format version: 1
1003 *
1004 *   Header Extent:
1005 *     Octets 0-7:        Unencrypted file size (big-endian)
1006 *     Octets 8-15:       eCryptfs special marker
1007 *     Octets 16-19:      Flags
1008 *      Octet 16:         File format version number (between 0 and 255)
1009 *      Octets 17-18:     Reserved
1010 *      Octet 19:         Bit 1 (lsb): Reserved
1011 *                        Bit 2: Encrypted?
1012 *                        Bits 3-8: Reserved
1013 *     Octets 20-23:      Header extent size (big-endian)
1014 *     Octets 24-25:      Number of header extents at front of file
1015 *                        (big-endian)
1016 *     Octet  26:         Begin RFC 2440 authentication token packet set
1017 *   Data Extent 0:
1018 *     Lower data (CBC encrypted)
1019 *   Data Extent 1:
1020 *     Lower data (CBC encrypted)
1021 *   ...
1022 *
1023 * Returns zero on success
1024 */
1025static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1026				       size_t *size,
1027				       struct ecryptfs_crypt_stat *crypt_stat,
1028				       struct dentry *ecryptfs_dentry)
1029{
1030	int rc;
1031	size_t written;
1032	size_t offset;
1033
1034	offset = ECRYPTFS_FILE_SIZE_BYTES;
1035	write_ecryptfs_marker((page_virt + offset), &written);
1036	offset += written;
1037	ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1038					&written);
1039	offset += written;
1040	ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1041				       &written);
1042	offset += written;
1043	rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1044					      ecryptfs_dentry, &written,
1045					      max - offset);
1046	if (rc)
1047		ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1048				"set; rc = [%d]\n", rc);
1049	if (size) {
1050		offset += written;
1051		*size = offset;
1052	}
1053	return rc;
1054}
1055
1056static int
1057ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1058				    char *virt, size_t virt_len)
1059{
1060	int rc;
1061
1062	rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1063				  0, virt_len);
1064	if (rc < 0)
1065		printk(KERN_ERR "%s: Error attempting to write header "
1066		       "information to lower file; rc = [%d]\n", __func__, rc);
1067	else
1068		rc = 0;
1069	return rc;
1070}
1071
1072static int
1073ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1074				 struct inode *ecryptfs_inode,
1075				 char *page_virt, size_t size)
1076{
1077	int rc;
1078	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
1079	struct inode *lower_inode = d_inode(lower_dentry);
1080
1081	if (!(lower_inode->i_opflags & IOP_XATTR)) {
1082		rc = -EOPNOTSUPP;
1083		goto out;
1084	}
1085
1086	inode_lock(lower_inode);
1087	rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
1088			    ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1089	if (!rc && ecryptfs_inode)
1090		fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
1091	inode_unlock(lower_inode);
1092out:
1093	return rc;
1094}
1095
1096static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1097					       unsigned int order)
1098{
1099	struct page *page;
1100
1101	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1102	if (page)
1103		return (unsigned long) page_address(page);
1104	return 0;
1105}
1106
1107/**
1108 * ecryptfs_write_metadata
1109 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1110 * @ecryptfs_inode: The newly created eCryptfs inode
1111 *
1112 * Write the file headers out.  This will likely involve a userspace
1113 * callout, in which the session key is encrypted with one or more
1114 * public keys and/or the passphrase necessary to do the encryption is
1115 * retrieved via a prompt.  Exactly what happens at this point should
1116 * be policy-dependent.
1117 *
1118 * Returns zero on success; non-zero on error
1119 */
1120int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1121			    struct inode *ecryptfs_inode)
1122{
1123	struct ecryptfs_crypt_stat *crypt_stat =
1124		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1125	unsigned int order;
1126	char *virt;
1127	size_t virt_len;
1128	size_t size = 0;
1129	int rc = 0;
1130
1131	if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1132		if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1133			printk(KERN_ERR "Key is invalid; bailing out\n");
1134			rc = -EINVAL;
1135			goto out;
1136		}
1137	} else {
1138		printk(KERN_WARNING "%s: Encrypted flag not set\n",
1139		       __func__);
1140		rc = -EINVAL;
1141		goto out;
1142	}
1143	virt_len = crypt_stat->metadata_size;
1144	order = get_order(virt_len);
1145	/* Released in this function */
1146	virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1147	if (!virt) {
1148		printk(KERN_ERR "%s: Out of memory\n", __func__);
1149		rc = -ENOMEM;
1150		goto out;
1151	}
1152	/* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1153	rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1154					 ecryptfs_dentry);
1155	if (unlikely(rc)) {
1156		printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1157		       __func__, rc);
1158		goto out_free;
1159	}
1160	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1161		rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1162						      virt, size);
1163	else
1164		rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1165							 virt_len);
1166	if (rc) {
1167		printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1168		       "rc = [%d]\n", __func__, rc);
1169		goto out_free;
1170	}
1171out_free:
1172	free_pages((unsigned long)virt, order);
1173out:
1174	return rc;
1175}
1176
1177#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1178#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1179static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1180				 char *virt, int *bytes_read,
1181				 int validate_header_size)
1182{
1183	int rc = 0;
1184	u32 header_extent_size;
1185	u16 num_header_extents_at_front;
1186
1187	header_extent_size = get_unaligned_be32(virt);
1188	virt += sizeof(__be32);
1189	num_header_extents_at_front = get_unaligned_be16(virt);
1190	crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1191				     * (size_t)header_extent_size));
1192	(*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1193	if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1194	    && (crypt_stat->metadata_size
1195		< ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1196		rc = -EINVAL;
1197		printk(KERN_WARNING "Invalid header size: [%zd]\n",
1198		       crypt_stat->metadata_size);
1199	}
1200	return rc;
1201}
1202
1203/**
1204 * set_default_header_data
1205 * @crypt_stat: The cryptographic context
1206 *
1207 * For version 0 file format; this function is only for backwards
1208 * compatibility for files created with the prior versions of
1209 * eCryptfs.
1210 */
1211static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1212{
1213	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1214}
1215
1216void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1217{
1218	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1219	struct ecryptfs_crypt_stat *crypt_stat;
1220	u64 file_size;
1221
1222	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1223	mount_crypt_stat =
1224		&ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1225	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1226		file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1227		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1228			file_size += crypt_stat->metadata_size;
1229	} else
1230		file_size = get_unaligned_be64(page_virt);
1231	i_size_write(inode, (loff_t)file_size);
1232	crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1233}
1234
1235/**
1236 * ecryptfs_read_headers_virt
1237 * @page_virt: The virtual address into which to read the headers
1238 * @crypt_stat: The cryptographic context
1239 * @ecryptfs_dentry: The eCryptfs dentry
1240 * @validate_header_size: Whether to validate the header size while reading
1241 *
1242 * Read/parse the header data. The header format is detailed in the
1243 * comment block for the ecryptfs_write_headers_virt() function.
1244 *
1245 * Returns zero on success
1246 */
1247static int ecryptfs_read_headers_virt(char *page_virt,
1248				      struct ecryptfs_crypt_stat *crypt_stat,
1249				      struct dentry *ecryptfs_dentry,
1250				      int validate_header_size)
1251{
1252	int rc = 0;
1253	int offset;
1254	int bytes_read;
1255
1256	ecryptfs_set_default_sizes(crypt_stat);
1257	crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1258		ecryptfs_dentry->d_sb)->mount_crypt_stat;
1259	offset = ECRYPTFS_FILE_SIZE_BYTES;
1260	rc = ecryptfs_validate_marker(page_virt + offset);
1261	if (rc)
1262		goto out;
1263	if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1264		ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1265	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1266	ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
1267	if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1268		ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1269				"file version [%d] is supported by this "
1270				"version of eCryptfs\n",
1271				crypt_stat->file_version,
1272				ECRYPTFS_SUPPORTED_FILE_VERSION);
1273		rc = -EINVAL;
1274		goto out;
1275	}
1276	offset += bytes_read;
1277	if (crypt_stat->file_version >= 1) {
1278		rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1279					   &bytes_read, validate_header_size);
1280		if (rc) {
1281			ecryptfs_printk(KERN_WARNING, "Error reading header "
1282					"metadata; rc = [%d]\n", rc);
1283		}
1284		offset += bytes_read;
1285	} else
1286		set_default_header_data(crypt_stat);
1287	rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1288				       ecryptfs_dentry);
1289out:
1290	return rc;
1291}
1292
1293/**
1294 * ecryptfs_read_xattr_region
1295 * @page_virt: The vitual address into which to read the xattr data
1296 * @ecryptfs_inode: The eCryptfs inode
1297 *
1298 * Attempts to read the crypto metadata from the extended attribute
1299 * region of the lower file.
1300 *
1301 * Returns zero on success; non-zero on error
1302 */
1303int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1304{
1305	struct dentry *lower_dentry =
1306		ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1307	ssize_t size;
1308	int rc = 0;
1309
1310	size = ecryptfs_getxattr_lower(lower_dentry,
1311				       ecryptfs_inode_to_lower(ecryptfs_inode),
1312				       ECRYPTFS_XATTR_NAME,
1313				       page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1314	if (size < 0) {
1315		if (unlikely(ecryptfs_verbosity > 0))
1316			printk(KERN_INFO "Error attempting to read the [%s] "
1317			       "xattr from the lower file; return value = "
1318			       "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1319		rc = -EINVAL;
1320		goto out;
1321	}
1322out:
1323	return rc;
1324}
1325
1326int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1327					    struct inode *inode)
1328{
1329	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1330	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1331	int rc;
1332
1333	rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1334				     ecryptfs_inode_to_lower(inode),
1335				     ECRYPTFS_XATTR_NAME, file_size,
1336				     ECRYPTFS_SIZE_AND_MARKER_BYTES);
1337	if (rc < 0)
1338		return rc;
1339	else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1340		return -EINVAL;
1341	rc = ecryptfs_validate_marker(marker);
1342	if (!rc)
1343		ecryptfs_i_size_init(file_size, inode);
1344	return rc;
1345}
1346
1347/*
1348 * ecryptfs_read_metadata
1349 *
1350 * Common entry point for reading file metadata. From here, we could
1351 * retrieve the header information from the header region of the file,
1352 * the xattr region of the file, or some other repository that is
1353 * stored separately from the file itself. The current implementation
1354 * supports retrieving the metadata information from the file contents
1355 * and from the xattr region.
1356 *
1357 * Returns zero if valid headers found and parsed; non-zero otherwise
1358 */
1359int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1360{
1361	int rc;
1362	char *page_virt;
1363	struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1364	struct ecryptfs_crypt_stat *crypt_stat =
1365	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1366	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1367		&ecryptfs_superblock_to_private(
1368			ecryptfs_dentry->d_sb)->mount_crypt_stat;
1369
1370	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1371						      mount_crypt_stat);
1372	/* Read the first page from the underlying file */
1373	page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1374	if (!page_virt) {
1375		rc = -ENOMEM;
1376		goto out;
1377	}
1378	rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1379				 ecryptfs_inode);
1380	if (rc >= 0)
1381		rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1382						ecryptfs_dentry,
1383						ECRYPTFS_VALIDATE_HEADER_SIZE);
1384	if (rc) {
1385		/* metadata is not in the file header, so try xattrs */
1386		memset(page_virt, 0, PAGE_SIZE);
1387		rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1388		if (rc) {
1389			printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1390			       "file header region or xattr region, inode %lu\n",
1391				ecryptfs_inode->i_ino);
1392			rc = -EINVAL;
1393			goto out;
1394		}
1395		rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1396						ecryptfs_dentry,
1397						ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1398		if (rc) {
1399			printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1400			       "file xattr region either, inode %lu\n",
1401				ecryptfs_inode->i_ino);
1402			rc = -EINVAL;
1403		}
1404		if (crypt_stat->mount_crypt_stat->flags
1405		    & ECRYPTFS_XATTR_METADATA_ENABLED) {
1406			crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1407		} else {
1408			printk(KERN_WARNING "Attempt to access file with "
1409			       "crypto metadata only in the extended attribute "
1410			       "region, but eCryptfs was mounted without "
1411			       "xattr support enabled. eCryptfs will not treat "
1412			       "this like an encrypted file, inode %lu\n",
1413				ecryptfs_inode->i_ino);
1414			rc = -EINVAL;
1415		}
1416	}
1417out:
1418	if (page_virt) {
1419		memset(page_virt, 0, PAGE_SIZE);
1420		kmem_cache_free(ecryptfs_header_cache, page_virt);
1421	}
1422	return rc;
1423}
1424
1425/*
1426 * ecryptfs_encrypt_filename - encrypt filename
1427 *
1428 * CBC-encrypts the filename. We do not want to encrypt the same
1429 * filename with the same key and IV, which may happen with hard
1430 * links, so we prepend random bits to each filename.
1431 *
1432 * Returns zero on success; non-zero otherwise
1433 */
1434static int
1435ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1436			  struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1437{
1438	int rc = 0;
1439
1440	filename->encrypted_filename = NULL;
1441	filename->encrypted_filename_size = 0;
1442	if (mount_crypt_stat && (mount_crypt_stat->flags
1443				     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1444		size_t packet_size;
1445		size_t remaining_bytes;
1446
1447		rc = ecryptfs_write_tag_70_packet(
1448			NULL, NULL,
1449			&filename->encrypted_filename_size,
1450			mount_crypt_stat, NULL,
1451			filename->filename_size);
1452		if (rc) {
1453			printk(KERN_ERR "%s: Error attempting to get packet "
1454			       "size for tag 72; rc = [%d]\n", __func__,
1455			       rc);
1456			filename->encrypted_filename_size = 0;
1457			goto out;
1458		}
1459		filename->encrypted_filename =
1460			kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1461		if (!filename->encrypted_filename) {
1462			rc = -ENOMEM;
1463			goto out;
1464		}
1465		remaining_bytes = filename->encrypted_filename_size;
1466		rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1467						  &remaining_bytes,
1468						  &packet_size,
1469						  mount_crypt_stat,
1470						  filename->filename,
1471						  filename->filename_size);
1472		if (rc) {
1473			printk(KERN_ERR "%s: Error attempting to generate "
1474			       "tag 70 packet; rc = [%d]\n", __func__,
1475			       rc);
1476			kfree(filename->encrypted_filename);
1477			filename->encrypted_filename = NULL;
1478			filename->encrypted_filename_size = 0;
1479			goto out;
1480		}
1481		filename->encrypted_filename_size = packet_size;
1482	} else {
1483		printk(KERN_ERR "%s: No support for requested filename "
1484		       "encryption method in this release\n", __func__);
1485		rc = -EOPNOTSUPP;
1486		goto out;
1487	}
1488out:
1489	return rc;
1490}
1491
1492static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1493				  const char *name, size_t name_size)
1494{
1495	int rc = 0;
1496
1497	(*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1498	if (!(*copied_name)) {
1499		rc = -ENOMEM;
1500		goto out;
1501	}
1502	memcpy((void *)(*copied_name), (void *)name, name_size);
1503	(*copied_name)[(name_size)] = '\0';	/* Only for convenience
1504						 * in printing out the
1505						 * string in debug
1506						 * messages */
1507	(*copied_name_size) = name_size;
1508out:
1509	return rc;
1510}
1511
1512/**
1513 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1514 * @key_tfm: Crypto context for key material, set by this function
1515 * @cipher_name: Name of the cipher
1516 * @key_size: Size of the key in bytes
1517 *
1518 * Returns zero on success. Any crypto_tfm structs allocated here
1519 * should be released by other functions, such as on a superblock put
1520 * event, regardless of whether this function succeeds for fails.
1521 */
1522static int
1523ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1524			    char *cipher_name, size_t *key_size)
1525{
1526	char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1527	char *full_alg_name = NULL;
1528	int rc;
1529
1530	*key_tfm = NULL;
1531	if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1532		rc = -EINVAL;
1533		printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1534		      "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1535		goto out;
1536	}
1537	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1538						    "ecb");
1539	if (rc)
1540		goto out;
1541	*key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1542	if (IS_ERR(*key_tfm)) {
1543		rc = PTR_ERR(*key_tfm);
1544		printk(KERN_ERR "Unable to allocate crypto cipher with name "
1545		       "[%s]; rc = [%d]\n", full_alg_name, rc);
1546		goto out;
1547	}
1548	crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1549	if (*key_size == 0)
1550		*key_size = crypto_skcipher_max_keysize(*key_tfm);
1551	get_random_bytes(dummy_key, *key_size);
1552	rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1553	if (rc) {
1554		printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1555		       "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1556		       rc);
1557		rc = -EINVAL;
1558		goto out;
1559	}
1560out:
1561	kfree(full_alg_name);
1562	return rc;
1563}
1564
1565struct kmem_cache *ecryptfs_key_tfm_cache;
1566static struct list_head key_tfm_list;
1567DEFINE_MUTEX(key_tfm_list_mutex);
1568
1569int __init ecryptfs_init_crypto(void)
1570{
1571	INIT_LIST_HEAD(&key_tfm_list);
1572	return 0;
1573}
1574
1575/**
1576 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1577 *
1578 * Called only at module unload time
1579 */
1580int ecryptfs_destroy_crypto(void)
1581{
1582	struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1583
1584	mutex_lock(&key_tfm_list_mutex);
1585	list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1586				 key_tfm_list) {
1587		list_del(&key_tfm->key_tfm_list);
1588		crypto_free_skcipher(key_tfm->key_tfm);
1589		kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1590	}
1591	mutex_unlock(&key_tfm_list_mutex);
1592	return 0;
1593}
1594
1595int
1596ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1597			 size_t key_size)
1598{
1599	struct ecryptfs_key_tfm *tmp_tfm;
1600	int rc = 0;
1601
1602	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1603
1604	tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1605	if (key_tfm)
1606		(*key_tfm) = tmp_tfm;
1607	if (!tmp_tfm) {
1608		rc = -ENOMEM;
1609		goto out;
1610	}
1611	mutex_init(&tmp_tfm->key_tfm_mutex);
1612	strscpy(tmp_tfm->cipher_name, cipher_name);
1613	tmp_tfm->key_size = key_size;
1614	rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1615					 tmp_tfm->cipher_name,
1616					 &tmp_tfm->key_size);
1617	if (rc) {
1618		printk(KERN_ERR "Error attempting to initialize key TFM "
1619		       "cipher with name = [%s]; rc = [%d]\n",
1620		       tmp_tfm->cipher_name, rc);
1621		kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1622		if (key_tfm)
1623			(*key_tfm) = NULL;
1624		goto out;
1625	}
1626	list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1627out:
1628	return rc;
1629}
1630
1631/**
1632 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1633 * @cipher_name: the name of the cipher to search for
1634 * @key_tfm: set to corresponding tfm if found
1635 *
1636 * Searches for cached key_tfm matching @cipher_name
1637 * Must be called with &key_tfm_list_mutex held
1638 * Returns 1 if found, with @key_tfm set
1639 * Returns 0 if not found, with @key_tfm set to NULL
1640 */
1641int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1642{
1643	struct ecryptfs_key_tfm *tmp_key_tfm;
1644
1645	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1646
1647	list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1648		if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1649			if (key_tfm)
1650				(*key_tfm) = tmp_key_tfm;
1651			return 1;
1652		}
1653	}
1654	if (key_tfm)
1655		(*key_tfm) = NULL;
1656	return 0;
1657}
1658
1659/**
1660 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1661 *
1662 * @tfm: set to cached tfm found, or new tfm created
1663 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1664 * @cipher_name: the name of the cipher to search for and/or add
1665 *
1666 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1667 * Searches for cached item first, and creates new if not found.
1668 * Returns 0 on success, non-zero if adding new cipher failed
1669 */
1670int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1671					       struct mutex **tfm_mutex,
1672					       char *cipher_name)
1673{
1674	struct ecryptfs_key_tfm *key_tfm;
1675	int rc = 0;
1676
1677	(*tfm) = NULL;
1678	(*tfm_mutex) = NULL;
1679
1680	mutex_lock(&key_tfm_list_mutex);
1681	if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1682		rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1683		if (rc) {
1684			printk(KERN_ERR "Error adding new key_tfm to list; "
1685					"rc = [%d]\n", rc);
1686			goto out;
1687		}
1688	}
1689	(*tfm) = key_tfm->key_tfm;
1690	(*tfm_mutex) = &key_tfm->key_tfm_mutex;
1691out:
1692	mutex_unlock(&key_tfm_list_mutex);
1693	return rc;
1694}
1695
1696/* 64 characters forming a 6-bit target field */
1697static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1698						 "EFGHIJKLMNOPQRST"
1699						 "UVWXYZabcdefghij"
1700						 "klmnopqrstuvwxyz");
1701
1702/* We could either offset on every reverse map or just pad some 0x00's
1703 * at the front here */
1704static const unsigned char filename_rev_map[256] = {
1705	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1706	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1707	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1708	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1709	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1710	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1711	0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1712	0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1713	0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1714	0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1715	0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1716	0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1717	0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1718	0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1719	0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1720	0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1721};
1722
1723/**
1724 * ecryptfs_encode_for_filename
1725 * @dst: Destination location for encoded filename
1726 * @dst_size: Size of the encoded filename in bytes
1727 * @src: Source location for the filename to encode
1728 * @src_size: Size of the source in bytes
1729 */
1730static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1731				  unsigned char *src, size_t src_size)
1732{
1733	size_t num_blocks;
1734	size_t block_num = 0;
1735	size_t dst_offset = 0;
1736	unsigned char last_block[3];
1737
1738	if (src_size == 0) {
1739		(*dst_size) = 0;
1740		goto out;
1741	}
1742	num_blocks = (src_size / 3);
1743	if ((src_size % 3) == 0) {
1744		memcpy(last_block, (&src[src_size - 3]), 3);
1745	} else {
1746		num_blocks++;
1747		last_block[2] = 0x00;
1748		switch (src_size % 3) {
1749		case 1:
1750			last_block[0] = src[src_size - 1];
1751			last_block[1] = 0x00;
1752			break;
1753		case 2:
1754			last_block[0] = src[src_size - 2];
1755			last_block[1] = src[src_size - 1];
1756		}
1757	}
1758	(*dst_size) = (num_blocks * 4);
1759	if (!dst)
1760		goto out;
1761	while (block_num < num_blocks) {
1762		unsigned char *src_block;
1763		unsigned char dst_block[4];
1764
1765		if (block_num == (num_blocks - 1))
1766			src_block = last_block;
1767		else
1768			src_block = &src[block_num * 3];
1769		dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1770		dst_block[1] = (((src_block[0] << 4) & 0x30)
1771				| ((src_block[1] >> 4) & 0x0F));
1772		dst_block[2] = (((src_block[1] << 2) & 0x3C)
1773				| ((src_block[2] >> 6) & 0x03));
1774		dst_block[3] = (src_block[2] & 0x3F);
1775		dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1776		dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1777		dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1778		dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1779		block_num++;
1780	}
1781out:
1782	return;
1783}
1784
1785static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1786{
1787	/* Not exact; conservatively long. Every block of 4
1788	 * encoded characters decodes into a block of 3
1789	 * decoded characters. This segment of code provides
1790	 * the caller with the maximum amount of allocated
1791	 * space that @dst will need to point to in a
1792	 * subsequent call. */
1793	return ((encoded_size + 1) * 3) / 4;
1794}
1795
1796/**
1797 * ecryptfs_decode_from_filename
1798 * @dst: If NULL, this function only sets @dst_size and returns. If
1799 *       non-NULL, this function decodes the encoded octets in @src
1800 *       into the memory that @dst points to.
1801 * @dst_size: Set to the size of the decoded string.
1802 * @src: The encoded set of octets to decode.
1803 * @src_size: The size of the encoded set of octets to decode.
1804 */
1805static void
1806ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1807			      const unsigned char *src, size_t src_size)
1808{
1809	u8 current_bit_offset = 0;
1810	size_t src_byte_offset = 0;
1811	size_t dst_byte_offset = 0;
1812
1813	if (!dst) {
1814		(*dst_size) = ecryptfs_max_decoded_size(src_size);
1815		goto out;
1816	}
1817	while (src_byte_offset < src_size) {
1818		unsigned char src_byte =
1819				filename_rev_map[(int)src[src_byte_offset]];
1820
1821		switch (current_bit_offset) {
1822		case 0:
1823			dst[dst_byte_offset] = (src_byte << 2);
1824			current_bit_offset = 6;
1825			break;
1826		case 6:
1827			dst[dst_byte_offset++] |= (src_byte >> 4);
1828			dst[dst_byte_offset] = ((src_byte & 0xF)
1829						 << 4);
1830			current_bit_offset = 4;
1831			break;
1832		case 4:
1833			dst[dst_byte_offset++] |= (src_byte >> 2);
1834			dst[dst_byte_offset] = (src_byte << 6);
1835			current_bit_offset = 2;
1836			break;
1837		case 2:
1838			dst[dst_byte_offset++] |= (src_byte);
1839			current_bit_offset = 0;
1840			break;
1841		}
1842		src_byte_offset++;
1843	}
1844	(*dst_size) = dst_byte_offset;
1845out:
1846	return;
1847}
1848
1849/**
1850 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1851 * @encoded_name: The encrypted name
1852 * @encoded_name_size: Length of the encrypted name
1853 * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1854 * @name: The plaintext name
1855 * @name_size: The length of the plaintext name
1856 *
1857 * Encrypts and encodes a filename into something that constitutes a
1858 * valid filename for a filesystem, with printable characters.
1859 *
1860 * We assume that we have a properly initialized crypto context,
1861 * pointed to by crypt_stat->tfm.
1862 *
1863 * Returns zero on success; non-zero on otherwise
1864 */
1865int ecryptfs_encrypt_and_encode_filename(
1866	char **encoded_name,
1867	size_t *encoded_name_size,
1868	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1869	const char *name, size_t name_size)
1870{
1871	size_t encoded_name_no_prefix_size;
1872	int rc = 0;
1873
1874	(*encoded_name) = NULL;
1875	(*encoded_name_size) = 0;
1876	if (mount_crypt_stat && (mount_crypt_stat->flags
1877				     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1878		struct ecryptfs_filename *filename;
1879
1880		filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1881		if (!filename) {
1882			rc = -ENOMEM;
1883			goto out;
1884		}
1885		filename->filename = (char *)name;
1886		filename->filename_size = name_size;
1887		rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1888		if (rc) {
1889			printk(KERN_ERR "%s: Error attempting to encrypt "
1890			       "filename; rc = [%d]\n", __func__, rc);
1891			kfree(filename);
1892			goto out;
1893		}
1894		ecryptfs_encode_for_filename(
1895			NULL, &encoded_name_no_prefix_size,
1896			filename->encrypted_filename,
1897			filename->encrypted_filename_size);
1898		if (mount_crypt_stat
1899			&& (mount_crypt_stat->flags
1900			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1901			(*encoded_name_size) =
1902				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1903				 + encoded_name_no_prefix_size);
1904		else
1905			(*encoded_name_size) =
1906				(ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1907				 + encoded_name_no_prefix_size);
1908		(*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1909		if (!(*encoded_name)) {
1910			rc = -ENOMEM;
1911			kfree(filename->encrypted_filename);
1912			kfree(filename);
1913			goto out;
1914		}
1915		if (mount_crypt_stat
1916			&& (mount_crypt_stat->flags
1917			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1918			memcpy((*encoded_name),
1919			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1920			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1921			ecryptfs_encode_for_filename(
1922			    ((*encoded_name)
1923			     + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1924			    &encoded_name_no_prefix_size,
1925			    filename->encrypted_filename,
1926			    filename->encrypted_filename_size);
1927			(*encoded_name_size) =
1928				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1929				 + encoded_name_no_prefix_size);
1930			(*encoded_name)[(*encoded_name_size)] = '\0';
1931		} else {
1932			rc = -EOPNOTSUPP;
1933		}
1934		if (rc) {
1935			printk(KERN_ERR "%s: Error attempting to encode "
1936			       "encrypted filename; rc = [%d]\n", __func__,
1937			       rc);
1938			kfree((*encoded_name));
1939			(*encoded_name) = NULL;
1940			(*encoded_name_size) = 0;
1941		}
1942		kfree(filename->encrypted_filename);
1943		kfree(filename);
1944	} else {
1945		rc = ecryptfs_copy_filename(encoded_name,
1946					    encoded_name_size,
1947					    name, name_size);
1948	}
1949out:
1950	return rc;
1951}
1952
1953/**
1954 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1955 * @plaintext_name: The plaintext name
1956 * @plaintext_name_size: The plaintext name size
1957 * @sb: Ecryptfs's super_block
1958 * @name: The filename in cipher text
1959 * @name_size: The cipher text name size
1960 *
1961 * Decrypts and decodes the filename.
1962 *
1963 * Returns zero on error; non-zero otherwise
1964 */
1965int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
1966					 size_t *plaintext_name_size,
1967					 struct super_block *sb,
1968					 const char *name, size_t name_size)
1969{
1970	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1971		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
1972	char *decoded_name;
1973	size_t decoded_name_size;
1974	size_t packet_size;
1975	int rc = 0;
1976
1977	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
1978	    !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
1979		if (is_dot_dotdot(name, name_size)) {
1980			rc = ecryptfs_copy_filename(plaintext_name,
1981						    plaintext_name_size,
1982						    name, name_size);
1983			goto out;
1984		}
1985
1986		if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
1987		    strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1988			    ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
1989			rc = -EINVAL;
1990			goto out;
1991		}
1992
1993		name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1994		name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1995		ecryptfs_decode_from_filename(NULL, &decoded_name_size,
1996					      name, name_size);
1997		decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
1998		if (!decoded_name) {
1999			rc = -ENOMEM;
2000			goto out;
2001		}
2002		ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2003					      name, name_size);
2004		rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2005						  plaintext_name_size,
2006						  &packet_size,
2007						  mount_crypt_stat,
2008						  decoded_name,
2009						  decoded_name_size);
2010		if (rc) {
2011			ecryptfs_printk(KERN_DEBUG,
2012					"%s: Could not parse tag 70 packet from filename\n",
2013					__func__);
2014			goto out_free;
2015		}
2016	} else {
2017		rc = ecryptfs_copy_filename(plaintext_name,
2018					    plaintext_name_size,
2019					    name, name_size);
2020		goto out;
2021	}
2022out_free:
2023	kfree(decoded_name);
2024out:
2025	return rc;
2026}
2027
2028#define ENC_NAME_MAX_BLOCKLEN_8_OR_16	143
2029
2030int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2031			   struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2032{
2033	struct crypto_skcipher *tfm;
2034	struct mutex *tfm_mutex;
2035	size_t cipher_blocksize;
2036	int rc;
2037
2038	if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2039		(*namelen) = lower_namelen;
2040		return 0;
2041	}
2042
2043	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2044			mount_crypt_stat->global_default_fn_cipher_name);
2045	if (unlikely(rc)) {
2046		(*namelen) = 0;
2047		return rc;
2048	}
2049
2050	mutex_lock(tfm_mutex);
2051	cipher_blocksize = crypto_skcipher_blocksize(tfm);
2052	mutex_unlock(tfm_mutex);
2053
2054	/* Return an exact amount for the common cases */
2055	if (lower_namelen == NAME_MAX
2056	    && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2057		(*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2058		return 0;
2059	}
2060
2061	/* Return a safe estimate for the uncommon cases */
2062	(*namelen) = lower_namelen;
2063	(*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2064	/* Since this is the max decoded size, subtract 1 "decoded block" len */
2065	(*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2066	(*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2067	(*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2068	/* Worst case is that the filename is padded nearly a full block size */
2069	(*namelen) -= cipher_blocksize - 1;
2070
2071	if ((*namelen) < 0)
2072		(*namelen) = 0;
2073
2074	return 0;
2075}