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