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