crypto.c

   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 */
  38void 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
  50static 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((*algified_name), algified_name_len, "%s(%s)",
  66		 chaining_modifier, cipher_name);
  67	rc = 0;
  68out:
  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 */
  81void 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(crypt_stat->root_iv, 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((src + crypt_stat->iv_bytes), 16, "%lld", offset);
  98	if (unlikely(ecryptfs_verbosity > 0)) {
  99		ecryptfs_printk(KERN_DEBUG, "source:\n");
 100		ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 101	}
 102	md5(src, crypt_stat->iv_bytes + 16, 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(iv, 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 */
 116void 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(&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 */
 132void 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(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(&key_sig->crypt_stat_list);
 140		kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 141	}
 142	memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 143}
 144
 145void 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(&auth_tok->mount_crypt_stat_list);
 157		if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 158			key_put(auth_tok->global_auth_tok_key);
 159		kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 160	}
 161	mutex_unlock(&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 */
 178int 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[i], pg, 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 */
 220static 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(crypt_stat->key,
 233				  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(&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			crypto_req_done, &ecr);
 247	/* Consider doing this once, when the file is opened */
 248	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 249		rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 250					    crypt_stat->key_size);
 251		if (rc) {
 252			ecryptfs_printk(KERN_ERR,
 253					"Error setting key; rc = [%d]\n",
 254					rc);
 255			mutex_unlock(&crypt_stat->cs_tfm_mutex);
 256			rc = -EINVAL;
 257			goto out;
 258		}
 259		crypt_stat->flags |= ECRYPTFS_KEY_SET;
 260	}
 261	mutex_unlock(&crypt_stat->cs_tfm_mutex);
 262	skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 263	rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
 264			     crypto_skcipher_decrypt(req);
 265	rc = crypto_wait_req(rc, &ecr);
 266out:
 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 */
 276static 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 */
 297static 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(extent_iv, crypt_stat, extent_base + extent_offset);
 311
 312	sg_init_table(&src_sg, 1);
 313	sg_init_table(&dst_sg, 1);
 314
 315	sg_set_page(&src_sg, src_page, extent_size,
 316		    extent_offset * extent_size);
 317	sg_set_page(&dst_sg, dst_page, extent_size,
 318		    extent_offset * extent_size);
 319
 320	rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 321			       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;
 329out:
 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 */
 349int 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(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, enc_extent_page,
 375				folio_page(folio, 0), 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(enc_extent_page);
 386	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, 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;
 396out:
 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 */
 419int 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(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, 0);
 435	rc = ecryptfs_read_lower(page_virt, 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, page, page, 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	}
 457out:
 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 */
 472int 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(&full_alg_name,
 488						    crypt_stat->cipher, "cbc");
 489	if (rc)
 490		goto out_unlock;
 491	crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
 492	if (IS_ERR(crypt_stat->tfm)) {
 493		rc = PTR_ERR(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(crypt_stat->tfm,
 501				  CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
 502	rc = 0;
 503out_free:
 504	kfree(full_alg_name);
 505out_unlock:
 506	mutex_unlock(&crypt_stat->cs_tfm_mutex);
 507	return rc;
 508}
 509
 510static 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
 526void 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 */
 549int 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(crypt_stat->key, crypt_stat->key_size, dst);
 563	memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 564	return 0;
 565}
 566
 567static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 568{
 569	get_random_bytes(crypt_stat->key, 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(crypt_stat->key,
 575				  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 */
 587static 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
 606static 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, global_auth_tok->sig);
 622		if (rc) {
 623			printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 624			goto out;
 625		}
 626	}
 627
 628out:
 629	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 630	mutex_unlock(&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 */
 641static 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(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 */
 674int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 675{
 676	struct ecryptfs_crypt_stat *crypt_stat =
 677	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 678	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 679	    &ecryptfs_superblock_to_private(
 680		    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);
 709out:
 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 */
 719static int ecryptfs_validate_marker(char *data)
 720{
 721	u32 m_1, m_2;
 722
 723	m_1 = get_unaligned_be32(data);
 724	m_2 = get_unaligned_be32(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
 735struct ecryptfs_flag_map_elem {
 736	u32 file_flag;
 737	u32 local_flag;
 738};
 739
 740/* Add support for additional flags by adding elements here. */
 741static 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 */
 754static 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(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 */
 778static void write_ecryptfs_marker(char *page_virt, size_t *written)
 779{
 780	u32 m_1, m_2;
 781
 782	get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 783	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 784	put_unaligned_be32(m_1, page_virt);
 785	page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 786	put_unaligned_be32(m_2, page_virt);
 787	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 788}
 789
 790void 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(flags, page_virt);
 803	(*written) = 4;
 804}
 805
 806struct 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. */
 814static struct ecryptfs_cipher_code_str_map_elem
 815ecryptfs_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 */
 833u8 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 */
 868int 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(str, 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
 885int 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(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
 892				 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(marker);
 898	if (!rc)
 899		ecryptfs_i_size_init(file_size, inode);
 900	return rc;
 901}
 902
 903void
 904ecryptfs_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(header_extent_size, virt);
 915	virt += 4;
 916	put_unaligned_be16(num_header_extents_at_front, virt);
 917	(*written) = 6;
 918}
 919
 920struct 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 */
 953static 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 + offset), &written);
 964	offset += written;
 965	ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
 966					&written);
 967	offset += written;
 968	ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
 969				       &written);
 970	offset += written;
 971	rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
 972					      ecryptfs_dentry, &written,
 973					      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
 984static int
 985ecryptfs_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, virt,
 991				  0, 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
1000static int
1001ecryptfs_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(ecryptfs_dentry);
1007	struct inode *lower_inode = d_inode(lower_dentry);
1008
1009	if (!(lower_inode->i_opflags & IOP_XATTR)) {
1010		rc = -EOPNOTSUPP;
1011		goto out;
1012	}
1013
1014	inode_lock(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(ecryptfs_inode, lower_inode);
1019	inode_unlock(lower_inode);
1020out:
1021	return rc;
1022}
1023
1024static 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 */
1048int 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(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(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(virt, virt_len, &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						      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	}
1099out_free:
1100	free_pages((unsigned long)virt, order);
1101out:
1102	return rc;
1103}
1104
1105#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1106#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1107static 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(virt);
1116	virt += sizeof(__be32);
1117	num_header_extents_at_front = get_unaligned_be16(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 */
1139static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1140{
1141	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1142}
1143
1144void 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(inode->i_sb)->mount_crypt_stat;
1153	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1154		file_size = i_size_read(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(page_virt);
1159	i_size_write(inode, (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 */
1175static 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		ecryptfs_dentry->d_sb)->mount_crypt_stat;
1187	offset = ECRYPTFS_FILE_SIZE_BYTES;
1188	rc = ecryptfs_validate_marker(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, d_inode(ecryptfs_dentry));
1193	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1194	ecryptfs_process_flags(crypt_stat, (page_virt + offset), &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, (page_virt + offset),
1207					   &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, (page_virt + offset),
1216				       ecryptfs_dentry);
1217out:
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 */
1231int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1232{
1233	struct dentry *lower_dentry =
1234		ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1235	ssize_t size;
1236	int rc = 0;
1237
1238	size = ecryptfs_getxattr_lower(lower_dentry,
1239				       ecryptfs_inode_to_lower(ecryptfs_inode),
1240				       ECRYPTFS_XATTR_NAME,
1241				       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	}
1250out:
1251	return rc;
1252}
1253
1254int 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(ecryptfs_dentry_to_lower(dentry),
1262				     ecryptfs_inode_to_lower(inode),
1263				     ECRYPTFS_XATTR_NAME, 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(marker);
1270	if (!rc)
1271		ecryptfs_i_size_init(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 */
1287int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1288{
1289	int rc;
1290	char *page_virt;
1291	struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1292	struct ecryptfs_crypt_stat *crypt_stat =
1293	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1294	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1295		&ecryptfs_superblock_to_private(
1296			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(page_virt, 0, 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	}
1345out:
1346	if (page_virt) {
1347		memset(page_virt, 0, PAGE_SIZE);
1348		kmem_cache_free(ecryptfs_header_cache, 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 */
1362static int
1363ecryptfs_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			&filename->encrypted_filename_size,
1378			mount_crypt_stat, NULL,
1379			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(filename->encrypted_filename,
1395						  &remaining_bytes,
1396						  &packet_size,
1397						  mount_crypt_stat,
1398						  filename->filename,
1399						  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(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	}
1416out:
1417	return rc;
1418}
1419
1420static 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;
1436out:
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 */
1450static int
1451ecryptfs_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(&full_alg_name, cipher_name,
1466						    "ecb");
1467	if (rc)
1468		goto out;
1469	*key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1470	if (IS_ERR(*key_tfm)) {
1471		rc = PTR_ERR(*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(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1477	if (*key_size == 0)
1478		*key_size = crypto_skcipher_max_keysize(*key_tfm);
1479	get_random_bytes(dummy_key, *key_size);
1480	rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *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	}
1488out:
1489	kfree(full_alg_name);
1490	return rc;
1491}
1492
1493struct kmem_cache *ecryptfs_key_tfm_cache;
1494static struct list_head key_tfm_list;
1495DEFINE_MUTEX(key_tfm_list_mutex);
1496
1497int __init ecryptfs_init_crypto(void)
1498{
1499	INIT_LIST_HEAD(&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 */
1508int 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(&key_tfm->key_tfm_list);
1516		crypto_free_skcipher(key_tfm->key_tfm);
1517		kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1518	}
1519	mutex_unlock(&key_tfm_list_mutex);
1520	return 0;
1521}
1522
1523int
1524ecryptfs_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(&tmp_tfm->key_tfm,
1543					 tmp_tfm->cipher_name,
1544					 &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(ecryptfs_key_tfm_cache, tmp_tfm);
1550		if (key_tfm)
1551			(*key_tfm) = NULL;
1552		goto out;
1553	}
1554	list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1555out:
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 */
1569int 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 */
1598int 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)) {
1610		rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 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;
1619out:
1620	mutex_unlock(&key_tfm_list_mutex);
1621	return rc;
1622}
1623
1624/* 64 characters forming a 6-bit target field */
1625static 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 */
1632static 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 */
1658static 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	}
1709out:
1710	return;
1711}
1712
1713static 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 */
1733static void
1734ecryptfs_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(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;
1773out:
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 */
1793int 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(filename);
1820			goto out;
1821		}
1822		ecryptfs_encode_for_filename(
1823			NULL, &encoded_name_no_prefix_size,
1824			filename->encrypted_filename,
1825			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(filename->encrypted_filename);
1840			kfree(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			    ((*encoded_name)
1851			     + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1852			    &encoded_name_no_prefix_size,
1853			    filename->encrypted_filename,
1854			    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((*encoded_name));
1867			(*encoded_name) = NULL;
1868			(*encoded_name_size) = 0;
1869		}
1870		kfree(filename->encrypted_filename);
1871		kfree(filename);
1872	} else {
1873		rc = ecryptfs_copy_filename(encoded_name,
1874					    encoded_name_size,
1875					    name, name_size);
1876	}
1877out:
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 */
1893int 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, name_size)) {
1908			rc = ecryptfs_copy_filename(plaintext_name,
1909						    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, &decoded_name_size,
1924					      name, 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(decoded_name, &decoded_name_size,
1931					      name, name_size);
1932		rc = ecryptfs_parse_tag_70_packet(plaintext_name,
1933						  plaintext_name_size,
1934						  &packet_size,
1935						  mount_crypt_stat,
1936						  decoded_name,
1937						  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(plaintext_name,
1946					    plaintext_name_size,
1947					    name, name_size);
1948		goto out;
1949	}
1950out_free:
1951	kfree(decoded_name);
1952out:
1953	return rc;
1954}
1955
1956#define ENC_NAME_MAX_BLOCKLEN_8_OR_16	143
1957
1958int 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_mutex,
1972			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(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(*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}