1/**
   2 * eCryptfs: Linux filesystem encryption layer
   3 *
   4 * Copyright (C) 1997-2004 Erez Zadok
   5 * Copyright (C) 2001-2004 Stony Brook University
   6 * Copyright (C) 2004-2007 International Business Machines Corp.
   7 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   8 *   		Michael C. Thompson <mcthomps@us.ibm.com>
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License as
  12 * published by the Free Software Foundation; either version 2 of the
  13 * License, or (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful, but
  16 * WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 * General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, write to the Free Software
  22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  23 * 02111-1307, USA.
  24 */
  25
  26#include <crypto/hash.h>
  27#include <crypto/skcipher.h>
  28#include <linux/fs.h>
  29#include <linux/mount.h>
  30#include <linux/pagemap.h>
  31#include <linux/random.h>
  32#include <linux/compiler.h>
  33#include <linux/key.h>
  34#include <linux/namei.h>
  35#include <linux/file.h>
  36#include <linux/scatterlist.h>
  37#include <linux/slab.h>
  38#include <asm/unaligned.h>
 
  39#include "ecryptfs_kernel.h"
  40
  41#define DECRYPT		0
  42#define ENCRYPT		1
  43
  44/**
  45 * ecryptfs_to_hex
  46 * @dst: Buffer to take hex character representation of contents of
  47 *       src; must be at least of size (src_size * 2)
  48 * @src: Buffer to be converted to a hex string respresentation
  49 * @src_size: number of bytes to convert
  50 */
  51void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
  52{
  53	int x;
  54
  55	for (x = 0; x < src_size; x++)
  56		sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
  57}
  58
  59/**
  60 * ecryptfs_from_hex
  61 * @dst: Buffer to take the bytes from src hex; must be at least of
  62 *       size (src_size / 2)
  63 * @src: Buffer to be converted from a hex string respresentation to raw value
  64 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  65 */
  66void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  67{
  68	int x;
  69	char tmp[3] = { 0, };
  70
  71	for (x = 0; x < dst_size; x++) {
  72		tmp[0] = src[x * 2];
  73		tmp[1] = src[x * 2 + 1];
  74		dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  75	}
  76}
  77
  78static int ecryptfs_hash_digest(struct crypto_shash *tfm,
  79				char *src, int len, char *dst)
  80{
  81	SHASH_DESC_ON_STACK(desc, tfm);
  82	int err;
  83
  84	desc->tfm = tfm;
  85	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  86	err = crypto_shash_digest(desc, src, len, dst);
  87	shash_desc_zero(desc);
  88	return err;
  89}
  90
  91/**
  92 * ecryptfs_calculate_md5 - calculates the md5 of @src
  93 * @dst: Pointer to 16 bytes of allocated memory
  94 * @crypt_stat: Pointer to crypt_stat struct for the current inode
  95 * @src: Data to be md5'd
  96 * @len: Length of @src
  97 *
  98 * Uses the allocated crypto context that crypt_stat references to
  99 * generate the MD5 sum of the contents of src.
 100 */
 101static int ecryptfs_calculate_md5(char *dst,
 102				  struct ecryptfs_crypt_stat *crypt_stat,
 103				  char *src, int len)
 104{
 105	struct crypto_shash *tfm;
 106	int rc = 0;
 107
 108	mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
 109	tfm = crypt_stat->hash_tfm;
 110	if (!tfm) {
 111		tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
 112		if (IS_ERR(tfm)) {
 113			rc = PTR_ERR(tfm);
 114			ecryptfs_printk(KERN_ERR, "Error attempting to "
 115					"allocate crypto context; rc = [%d]\n",
 116					rc);
 117			goto out;
 118		}
 119		crypt_stat->hash_tfm = tfm;
 120	}
 121	rc = ecryptfs_hash_digest(tfm, src, len, dst);
 122	if (rc) {
 123		printk(KERN_ERR
 124		       "%s: Error computing crypto hash; rc = [%d]\n",
 125		       __func__, rc);
 126		goto out;
 127	}
 128out:
 129	mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
 130	return rc;
 131}
 132
 133static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
 134						  char *cipher_name,
 135						  char *chaining_modifier)
 136{
 137	int cipher_name_len = strlen(cipher_name);
 138	int chaining_modifier_len = strlen(chaining_modifier);
 139	int algified_name_len;
 140	int rc;
 141
 142	algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
 143	(*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
 144	if (!(*algified_name)) {
 145		rc = -ENOMEM;
 146		goto out;
 147	}
 148	snprintf((*algified_name), algified_name_len, "%s(%s)",
 149		 chaining_modifier, cipher_name);
 150	rc = 0;
 151out:
 152	return rc;
 153}
 154
 155/**
 156 * ecryptfs_derive_iv
 157 * @iv: destination for the derived iv vale
 158 * @crypt_stat: Pointer to crypt_stat struct for the current inode
 159 * @offset: Offset of the extent whose IV we are to derive
 160 *
 161 * Generate the initialization vector from the given root IV and page
 162 * offset.
 163 *
 164 * Returns zero on success; non-zero on error.
 165 */
 166int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 167		       loff_t offset)
 168{
 169	int rc = 0;
 170	char dst[MD5_DIGEST_SIZE];
 171	char src[ECRYPTFS_MAX_IV_BYTES + 16];
 172
 173	if (unlikely(ecryptfs_verbosity > 0)) {
 174		ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 175		ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 176	}
 177	/* TODO: It is probably secure to just cast the least
 178	 * significant bits of the root IV into an unsigned long and
 179	 * add the offset to that rather than go through all this
 180	 * hashing business. -Halcrow */
 181	memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 182	memset((src + crypt_stat->iv_bytes), 0, 16);
 183	snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
 184	if (unlikely(ecryptfs_verbosity > 0)) {
 185		ecryptfs_printk(KERN_DEBUG, "source:\n");
 186		ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 187	}
 188	rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 189				    (crypt_stat->iv_bytes + 16));
 190	if (rc) {
 191		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 192				"MD5 while generating IV for a page\n");
 193		goto out;
 194	}
 195	memcpy(iv, dst, crypt_stat->iv_bytes);
 196	if (unlikely(ecryptfs_verbosity > 0)) {
 197		ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 198		ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 199	}
 200out:
 201	return rc;
 202}
 203
 204/**
 205 * ecryptfs_init_crypt_stat
 206 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 207 *
 208 * Initialize the crypt_stat structure.
 209 */
 210void
 211ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 212{
 
 
 
 
 
 
 
 
 
 
 
 
 213	memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 214	INIT_LIST_HEAD(&crypt_stat->keysig_list);
 215	mutex_init(&crypt_stat->keysig_list_mutex);
 216	mutex_init(&crypt_stat->cs_mutex);
 217	mutex_init(&crypt_stat->cs_tfm_mutex);
 218	mutex_init(&crypt_stat->cs_hash_tfm_mutex);
 219	crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 
 
 220}
 221
 222/**
 223 * ecryptfs_destroy_crypt_stat
 224 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 225 *
 226 * Releases all memory associated with a crypt_stat struct.
 227 */
 228void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 229{
 230	struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 231
 232	crypto_free_skcipher(crypt_stat->tfm);
 233	crypto_free_shash(crypt_stat->hash_tfm);
 234	list_for_each_entry_safe(key_sig, key_sig_tmp,
 235				 &crypt_stat->keysig_list, crypt_stat_list) {
 236		list_del(&key_sig->crypt_stat_list);
 237		kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 238	}
 239	memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 240}
 241
 242void ecryptfs_destroy_mount_crypt_stat(
 243	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 244{
 245	struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 246
 247	if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 248		return;
 249	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 250	list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 251				 &mount_crypt_stat->global_auth_tok_list,
 252				 mount_crypt_stat_list) {
 253		list_del(&auth_tok->mount_crypt_stat_list);
 254		if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 255			key_put(auth_tok->global_auth_tok_key);
 256		kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 257	}
 258	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 259	memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 260}
 261
 262/**
 263 * virt_to_scatterlist
 264 * @addr: Virtual address
 265 * @size: Size of data; should be an even multiple of the block size
 266 * @sg: Pointer to scatterlist array; set to NULL to obtain only
 267 *      the number of scatterlist structs required in array
 268 * @sg_size: Max array size
 269 *
 270 * Fills in a scatterlist array with page references for a passed
 271 * virtual address.
 272 *
 273 * Returns the number of scatterlist structs in array used
 274 */
 275int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 276			int sg_size)
 277{
 278	int i = 0;
 279	struct page *pg;
 280	int offset;
 281	int remainder_of_page;
 282
 283	sg_init_table(sg, sg_size);
 284
 285	while (size > 0 && i < sg_size) {
 286		pg = virt_to_page(addr);
 287		offset = offset_in_page(addr);
 288		sg_set_page(&sg[i], pg, 0, offset);
 289		remainder_of_page = PAGE_SIZE - offset;
 290		if (size >= remainder_of_page) {
 291			sg[i].length = remainder_of_page;
 292			addr += remainder_of_page;
 293			size -= remainder_of_page;
 294		} else {
 295			sg[i].length = size;
 296			addr += size;
 297			size = 0;
 298		}
 299		i++;
 300	}
 301	if (size > 0)
 302		return -ENOMEM;
 303	return i;
 304}
 305
 306struct extent_crypt_result {
 307	struct completion completion;
 308	int rc;
 309};
 310
 311static void extent_crypt_complete(struct crypto_async_request *req, int rc)
 312{
 313	struct extent_crypt_result *ecr = req->data;
 314
 315	if (rc == -EINPROGRESS)
 316		return;
 317
 318	ecr->rc = rc;
 319	complete(&ecr->completion);
 320}
 321
 322/**
 323 * crypt_scatterlist
 324 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 325 * @dst_sg: Destination of the data after performing the crypto operation
 326 * @src_sg: Data to be encrypted or decrypted
 327 * @size: Length of data
 328 * @iv: IV to use
 329 * @op: ENCRYPT or DECRYPT to indicate the desired operation
 330 *
 331 * Returns the number of bytes encrypted or decrypted; negative value on error
 332 */
 333static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 334			     struct scatterlist *dst_sg,
 335			     struct scatterlist *src_sg, int size,
 336			     unsigned char *iv, int op)
 337{
 338	struct skcipher_request *req = NULL;
 339	struct extent_crypt_result ecr;
 340	int rc = 0;
 341
 342	BUG_ON(!crypt_stat || !crypt_stat->tfm
 343	       || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 344	if (unlikely(ecryptfs_verbosity > 0)) {
 345		ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 346				crypt_stat->key_size);
 347		ecryptfs_dump_hex(crypt_stat->key,
 348				  crypt_stat->key_size);
 349	}
 350
 351	init_completion(&ecr.completion);
 352
 353	mutex_lock(&crypt_stat->cs_tfm_mutex);
 354	req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
 355	if (!req) {
 356		mutex_unlock(&crypt_stat->cs_tfm_mutex);
 357		rc = -ENOMEM;
 358		goto out;
 359	}
 360
 361	skcipher_request_set_callback(req,
 362			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 363			extent_crypt_complete, &ecr);
 364	/* Consider doing this once, when the file is opened */
 365	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 366		rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 367					    crypt_stat->key_size);
 368		if (rc) {
 369			ecryptfs_printk(KERN_ERR,
 370					"Error setting key; rc = [%d]\n",
 371					rc);
 372			mutex_unlock(&crypt_stat->cs_tfm_mutex);
 373			rc = -EINVAL;
 374			goto out;
 375		}
 376		crypt_stat->flags |= ECRYPTFS_KEY_SET;
 377	}
 378	mutex_unlock(&crypt_stat->cs_tfm_mutex);
 379	skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 380	rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
 381			     crypto_skcipher_decrypt(req);
 382	if (rc == -EINPROGRESS || rc == -EBUSY) {
 383		struct extent_crypt_result *ecr = req->base.data;
 384
 385		wait_for_completion(&ecr->completion);
 386		rc = ecr->rc;
 387		reinit_completion(&ecr->completion);
 388	}
 389out:
 390	skcipher_request_free(req);
 391	return rc;
 392}
 393
 394/**
 395 * lower_offset_for_page
 396 *
 397 * Convert an eCryptfs page index into a lower byte offset
 398 */
 399static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 400				    struct page *page)
 401{
 402	return ecryptfs_lower_header_size(crypt_stat) +
 403	       ((loff_t)page->index << PAGE_SHIFT);
 404}
 405
 406/**
 407 * crypt_extent
 408 * @crypt_stat: crypt_stat containing cryptographic context for the
 409 *              encryption operation
 410 * @dst_page: The page to write the result into
 411 * @src_page: The page to read from
 412 * @extent_offset: Page extent offset for use in generating IV
 413 * @op: ENCRYPT or DECRYPT to indicate the desired operation
 414 *
 415 * Encrypts or decrypts one extent of data.
 416 *
 417 * Return zero on success; non-zero otherwise
 418 */
 419static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 420			struct page *dst_page,
 421			struct page *src_page,
 422			unsigned long extent_offset, int op)
 423{
 424	pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
 425	loff_t extent_base;
 426	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 427	struct scatterlist src_sg, dst_sg;
 428	size_t extent_size = crypt_stat->extent_size;
 429	int rc;
 430
 431	extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
 432	rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 433				(extent_base + extent_offset));
 434	if (rc) {
 435		ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 436			"extent [0x%.16llx]; rc = [%d]\n",
 437			(unsigned long long)(extent_base + extent_offset), rc);
 438		goto out;
 439	}
 440
 441	sg_init_table(&src_sg, 1);
 442	sg_init_table(&dst_sg, 1);
 443
 444	sg_set_page(&src_sg, src_page, extent_size,
 445		    extent_offset * extent_size);
 446	sg_set_page(&dst_sg, dst_page, extent_size,
 447		    extent_offset * extent_size);
 448
 449	rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 450			       extent_iv, op);
 451	if (rc < 0) {
 452		printk(KERN_ERR "%s: Error attempting to crypt page with "
 453		       "page_index = [%ld], extent_offset = [%ld]; "
 454		       "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 455		goto out;
 456	}
 457	rc = 0;
 458out:
 459	return rc;
 460}
 461
 462/**
 463 * ecryptfs_encrypt_page
 464 * @page: Page mapped from the eCryptfs inode for the file; contains
 465 *        decrypted content that needs to be encrypted (to a temporary
 466 *        page; not in place) and written out to the lower file
 467 *
 468 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 469 * that eCryptfs pages may straddle the lower pages -- for instance,
 470 * if the file was created on a machine with an 8K page size
 471 * (resulting in an 8K header), and then the file is copied onto a
 472 * host with a 32K page size, then when reading page 0 of the eCryptfs
 473 * file, 24K of page 0 of the lower file will be read and decrypted,
 474 * and then 8K of page 1 of the lower file will be read and decrypted.
 475 *
 476 * Returns zero on success; negative on error
 477 */
 478int ecryptfs_encrypt_page(struct page *page)
 479{
 480	struct inode *ecryptfs_inode;
 481	struct ecryptfs_crypt_stat *crypt_stat;
 482	char *enc_extent_virt;
 483	struct page *enc_extent_page = NULL;
 484	loff_t extent_offset;
 485	loff_t lower_offset;
 486	int rc = 0;
 487
 488	ecryptfs_inode = page->mapping->host;
 489	crypt_stat =
 490		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 491	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 492	enc_extent_page = alloc_page(GFP_USER);
 493	if (!enc_extent_page) {
 494		rc = -ENOMEM;
 495		ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 496				"encrypted extent\n");
 497		goto out;
 498	}
 499
 500	for (extent_offset = 0;
 501	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 502	     extent_offset++) {
 503		rc = crypt_extent(crypt_stat, enc_extent_page, page,
 504				  extent_offset, ENCRYPT);
 505		if (rc) {
 506			printk(KERN_ERR "%s: Error encrypting extent; "
 507			       "rc = [%d]\n", __func__, rc);
 508			goto out;
 509		}
 510	}
 511
 512	lower_offset = lower_offset_for_page(crypt_stat, page);
 513	enc_extent_virt = kmap(enc_extent_page);
 514	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 515				  PAGE_SIZE);
 516	kunmap(enc_extent_page);
 517	if (rc < 0) {
 518		ecryptfs_printk(KERN_ERR,
 519			"Error attempting to write lower page; rc = [%d]\n",
 520			rc);
 521		goto out;
 522	}
 523	rc = 0;
 524out:
 525	if (enc_extent_page) {
 526		__free_page(enc_extent_page);
 527	}
 528	return rc;
 529}
 530
 531/**
 532 * ecryptfs_decrypt_page
 533 * @page: Page mapped from the eCryptfs inode for the file; data read
 534 *        and decrypted from the lower file will be written into this
 535 *        page
 536 *
 537 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 538 * that eCryptfs pages may straddle the lower pages -- for instance,
 539 * if the file was created on a machine with an 8K page size
 540 * (resulting in an 8K header), and then the file is copied onto a
 541 * host with a 32K page size, then when reading page 0 of the eCryptfs
 542 * file, 24K of page 0 of the lower file will be read and decrypted,
 543 * and then 8K of page 1 of the lower file will be read and decrypted.
 544 *
 545 * Returns zero on success; negative on error
 546 */
 547int ecryptfs_decrypt_page(struct page *page)
 548{
 549	struct inode *ecryptfs_inode;
 550	struct ecryptfs_crypt_stat *crypt_stat;
 551	char *page_virt;
 552	unsigned long extent_offset;
 553	loff_t lower_offset;
 554	int rc = 0;
 555
 556	ecryptfs_inode = page->mapping->host;
 557	crypt_stat =
 558		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 559	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 560
 561	lower_offset = lower_offset_for_page(crypt_stat, page);
 562	page_virt = kmap(page);
 563	rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
 564				 ecryptfs_inode);
 565	kunmap(page);
 566	if (rc < 0) {
 567		ecryptfs_printk(KERN_ERR,
 568			"Error attempting to read lower page; rc = [%d]\n",
 569			rc);
 570		goto out;
 571	}
 572
 573	for (extent_offset = 0;
 574	     extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 575	     extent_offset++) {
 576		rc = crypt_extent(crypt_stat, page, page,
 577				  extent_offset, DECRYPT);
 578		if (rc) {
 579			printk(KERN_ERR "%s: Error encrypting extent; "
 580			       "rc = [%d]\n", __func__, rc);
 581			goto out;
 582		}
 583	}
 584out:
 585	return rc;
 586}
 587
 588#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 589
 590/**
 591 * ecryptfs_init_crypt_ctx
 592 * @crypt_stat: Uninitialized crypt stats structure
 593 *
 594 * Initialize the crypto context.
 595 *
 596 * TODO: Performance: Keep a cache of initialized cipher contexts;
 597 * only init if needed
 598 */
 599int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 600{
 601	char *full_alg_name;
 602	int rc = -EINVAL;
 603
 604	ecryptfs_printk(KERN_DEBUG,
 605			"Initializing cipher [%s]; strlen = [%d]; "
 606			"key_size_bits = [%zd]\n",
 607			crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 608			crypt_stat->key_size << 3);
 609	mutex_lock(&crypt_stat->cs_tfm_mutex);
 610	if (crypt_stat->tfm) {
 611		rc = 0;
 612		goto out_unlock;
 613	}
 614	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 615						    crypt_stat->cipher, "cbc");
 616	if (rc)
 617		goto out_unlock;
 618	crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
 619	if (IS_ERR(crypt_stat->tfm)) {
 620		rc = PTR_ERR(crypt_stat->tfm);
 621		crypt_stat->tfm = NULL;
 622		ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 623				"Error initializing cipher [%s]\n",
 624				full_alg_name);
 625		goto out_free;
 626	}
 627	crypto_skcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 628	rc = 0;
 629out_free:
 630	kfree(full_alg_name);
 631out_unlock:
 632	mutex_unlock(&crypt_stat->cs_tfm_mutex);
 633	return rc;
 634}
 635
 636static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 637{
 638	int extent_size_tmp;
 639
 640	crypt_stat->extent_mask = 0xFFFFFFFF;
 641	crypt_stat->extent_shift = 0;
 642	if (crypt_stat->extent_size == 0)
 643		return;
 644	extent_size_tmp = crypt_stat->extent_size;
 645	while ((extent_size_tmp & 0x01) == 0) {
 646		extent_size_tmp >>= 1;
 647		crypt_stat->extent_mask <<= 1;
 648		crypt_stat->extent_shift++;
 649	}
 650}
 651
 652void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 653{
 654	/* Default values; may be overwritten as we are parsing the
 655	 * packets. */
 656	crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 657	set_extent_mask_and_shift(crypt_stat);
 658	crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 659	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 660		crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 661	else {
 662		if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 663			crypt_stat->metadata_size =
 664				ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 665		else
 666			crypt_stat->metadata_size = PAGE_SIZE;
 667	}
 668}
 669
 670/**
 671 * ecryptfs_compute_root_iv
 672 * @crypt_stats
 673 *
 674 * On error, sets the root IV to all 0's.
 675 */
 676int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 677{
 678	int rc = 0;
 679	char dst[MD5_DIGEST_SIZE];
 680
 681	BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 682	BUG_ON(crypt_stat->iv_bytes <= 0);
 683	if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 684		rc = -EINVAL;
 685		ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 686				"cannot generate root IV\n");
 687		goto out;
 688	}
 689	rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 690				    crypt_stat->key_size);
 691	if (rc) {
 692		ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 693				"MD5 while generating root IV\n");
 694		goto out;
 695	}
 696	memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 697out:
 698	if (rc) {
 699		memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 700		crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 701	}
 702	return rc;
 703}
 704
 705static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 706{
 707	get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 708	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 709	ecryptfs_compute_root_iv(crypt_stat);
 710	if (unlikely(ecryptfs_verbosity > 0)) {
 711		ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 712		ecryptfs_dump_hex(crypt_stat->key,
 713				  crypt_stat->key_size);
 714	}
 715}
 716
 717/**
 718 * ecryptfs_copy_mount_wide_flags_to_inode_flags
 719 * @crypt_stat: The inode's cryptographic context
 720 * @mount_crypt_stat: The mount point's cryptographic context
 721 *
 722 * This function propagates the mount-wide flags to individual inode
 723 * flags.
 724 */
 725static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 726	struct ecryptfs_crypt_stat *crypt_stat,
 727	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 728{
 729	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 730		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 731	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 732		crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 733	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 734		crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 735		if (mount_crypt_stat->flags
 736		    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 737			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 738		else if (mount_crypt_stat->flags
 739			 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 740			crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 741	}
 742}
 743
 744static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 745	struct ecryptfs_crypt_stat *crypt_stat,
 746	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 747{
 748	struct ecryptfs_global_auth_tok *global_auth_tok;
 749	int rc = 0;
 750
 751	mutex_lock(&crypt_stat->keysig_list_mutex);
 752	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 753
 754	list_for_each_entry(global_auth_tok,
 755			    &mount_crypt_stat->global_auth_tok_list,
 756			    mount_crypt_stat_list) {
 757		if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 758			continue;
 759		rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 760		if (rc) {
 761			printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 762			goto out;
 763		}
 764	}
 765
 766out:
 767	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 768	mutex_unlock(&crypt_stat->keysig_list_mutex);
 769	return rc;
 770}
 771
 772/**
 773 * ecryptfs_set_default_crypt_stat_vals
 774 * @crypt_stat: The inode's cryptographic context
 775 * @mount_crypt_stat: The mount point's cryptographic context
 776 *
 777 * Default values in the event that policy does not override them.
 778 */
 779static void ecryptfs_set_default_crypt_stat_vals(
 780	struct ecryptfs_crypt_stat *crypt_stat,
 781	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 782{
 783	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 784						      mount_crypt_stat);
 785	ecryptfs_set_default_sizes(crypt_stat);
 786	strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 787	crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 788	crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 789	crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 790	crypt_stat->mount_crypt_stat = mount_crypt_stat;
 791}
 792
 793/**
 794 * ecryptfs_new_file_context
 795 * @ecryptfs_inode: The eCryptfs inode
 796 *
 797 * If the crypto context for the file has not yet been established,
 798 * this is where we do that.  Establishing a new crypto context
 799 * involves the following decisions:
 800 *  - What cipher to use?
 801 *  - What set of authentication tokens to use?
 802 * Here we just worry about getting enough information into the
 803 * authentication tokens so that we know that they are available.
 804 * We associate the available authentication tokens with the new file
 805 * via the set of signatures in the crypt_stat struct.  Later, when
 806 * the headers are actually written out, we may again defer to
 807 * userspace to perform the encryption of the session key; for the
 808 * foreseeable future, this will be the case with public key packets.
 809 *
 810 * Returns zero on success; non-zero otherwise
 811 */
 812int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 813{
 814	struct ecryptfs_crypt_stat *crypt_stat =
 815	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 816	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 817	    &ecryptfs_superblock_to_private(
 818		    ecryptfs_inode->i_sb)->mount_crypt_stat;
 819	int cipher_name_len;
 820	int rc = 0;
 821
 822	ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 823	crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 824	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 825						      mount_crypt_stat);
 826	rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 827							 mount_crypt_stat);
 828	if (rc) {
 829		printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 830		       "to the inode key sigs; rc = [%d]\n", rc);
 831		goto out;
 832	}
 833	cipher_name_len =
 834		strlen(mount_crypt_stat->global_default_cipher_name);
 835	memcpy(crypt_stat->cipher,
 836	       mount_crypt_stat->global_default_cipher_name,
 837	       cipher_name_len);
 838	crypt_stat->cipher[cipher_name_len] = '\0';
 839	crypt_stat->key_size =
 840		mount_crypt_stat->global_default_cipher_key_size;
 841	ecryptfs_generate_new_key(crypt_stat);
 842	rc = ecryptfs_init_crypt_ctx(crypt_stat);
 843	if (rc)
 844		ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 845				"context for cipher [%s]: rc = [%d]\n",
 846				crypt_stat->cipher, rc);
 847out:
 848	return rc;
 849}
 850
 851/**
 852 * ecryptfs_validate_marker - check for the ecryptfs marker
 853 * @data: The data block in which to check
 854 *
 855 * Returns zero if marker found; -EINVAL if not found
 856 */
 857static int ecryptfs_validate_marker(char *data)
 858{
 859	u32 m_1, m_2;
 860
 861	m_1 = get_unaligned_be32(data);
 862	m_2 = get_unaligned_be32(data + 4);
 863	if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 864		return 0;
 865	ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
 866			"MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
 867			MAGIC_ECRYPTFS_MARKER);
 868	ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
 869			"[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
 870	return -EINVAL;
 871}
 872
 873struct ecryptfs_flag_map_elem {
 874	u32 file_flag;
 875	u32 local_flag;
 876};
 877
 878/* Add support for additional flags by adding elements here. */
 879static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 880	{0x00000001, ECRYPTFS_ENABLE_HMAC},
 881	{0x00000002, ECRYPTFS_ENCRYPTED},
 882	{0x00000004, ECRYPTFS_METADATA_IN_XATTR},
 883	{0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 884};
 885
 886/**
 887 * ecryptfs_process_flags
 888 * @crypt_stat: The cryptographic context
 889 * @page_virt: Source data to be parsed
 890 * @bytes_read: Updated with the number of bytes read
 891 *
 892 * Returns zero on success; non-zero if the flag set is invalid
 893 */
 894static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
 895				  char *page_virt, int *bytes_read)
 896{
 897	int rc = 0;
 898	int i;
 899	u32 flags;
 900
 901	flags = get_unaligned_be32(page_virt);
 902	for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 903			  / sizeof(struct ecryptfs_flag_map_elem))); i++)
 904		if (flags & ecryptfs_flag_map[i].file_flag) {
 905			crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
 906		} else
 907			crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
 908	/* Version is in top 8 bits of the 32-bit flag vector */
 909	crypt_stat->file_version = ((flags >> 24) & 0xFF);
 910	(*bytes_read) = 4;
 911	return rc;
 912}
 913
 914/**
 915 * write_ecryptfs_marker
 916 * @page_virt: The pointer to in a page to begin writing the marker
 917 * @written: Number of bytes written
 918 *
 919 * Marker = 0x3c81b7f5
 920 */
 921static void write_ecryptfs_marker(char *page_virt, size_t *written)
 922{
 923	u32 m_1, m_2;
 924
 925	get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 926	m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 927	put_unaligned_be32(m_1, page_virt);
 928	page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 929	put_unaligned_be32(m_2, page_virt);
 930	(*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 931}
 932
 933void ecryptfs_write_crypt_stat_flags(char *page_virt,
 934				     struct ecryptfs_crypt_stat *crypt_stat,
 935				     size_t *written)
 936{
 937	u32 flags = 0;
 938	int i;
 939
 940	for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 941			  / sizeof(struct ecryptfs_flag_map_elem))); i++)
 942		if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
 943			flags |= ecryptfs_flag_map[i].file_flag;
 944	/* Version is in top 8 bits of the 32-bit flag vector */
 945	flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
 946	put_unaligned_be32(flags, page_virt);
 947	(*written) = 4;
 948}
 949
 950struct ecryptfs_cipher_code_str_map_elem {
 951	char cipher_str[16];
 952	u8 cipher_code;
 953};
 954
 955/* Add support for additional ciphers by adding elements here. The
 956 * cipher_code is whatever OpenPGP applicatoins use to identify the
 957 * ciphers. List in order of probability. */
 958static struct ecryptfs_cipher_code_str_map_elem
 959ecryptfs_cipher_code_str_map[] = {
 960	{"aes",RFC2440_CIPHER_AES_128 },
 961	{"blowfish", RFC2440_CIPHER_BLOWFISH},
 962	{"des3_ede", RFC2440_CIPHER_DES3_EDE},
 963	{"cast5", RFC2440_CIPHER_CAST_5},
 964	{"twofish", RFC2440_CIPHER_TWOFISH},
 965	{"cast6", RFC2440_CIPHER_CAST_6},
 966	{"aes", RFC2440_CIPHER_AES_192},
 967	{"aes", RFC2440_CIPHER_AES_256}
 968};
 969
 970/**
 971 * ecryptfs_code_for_cipher_string
 972 * @cipher_name: The string alias for the cipher
 973 * @key_bytes: Length of key in bytes; used for AES code selection
 974 *
 975 * Returns zero on no match, or the cipher code on match
 976 */
 977u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 978{
 979	int i;
 980	u8 code = 0;
 981	struct ecryptfs_cipher_code_str_map_elem *map =
 982		ecryptfs_cipher_code_str_map;
 983
 984	if (strcmp(cipher_name, "aes") == 0) {
 985		switch (key_bytes) {
 986		case 16:
 987			code = RFC2440_CIPHER_AES_128;
 988			break;
 989		case 24:
 990			code = RFC2440_CIPHER_AES_192;
 991			break;
 992		case 32:
 993			code = RFC2440_CIPHER_AES_256;
 994		}
 995	} else {
 996		for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
 997			if (strcmp(cipher_name, map[i].cipher_str) == 0) {
 998				code = map[i].cipher_code;
 999				break;
1000			}
1001	}
1002	return code;
1003}
1004
1005/**
1006 * ecryptfs_cipher_code_to_string
1007 * @str: Destination to write out the cipher name
1008 * @cipher_code: The code to convert to cipher name string
1009 *
1010 * Returns zero on success
1011 */
1012int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1013{
1014	int rc = 0;
1015	int i;
1016
1017	str[0] = '\0';
1018	for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1019		if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1020			strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1021	if (str[0] == '\0') {
1022		ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1023				"[%d]\n", cipher_code);
1024		rc = -EINVAL;
1025	}
1026	return rc;
1027}
1028
1029int ecryptfs_read_and_validate_header_region(struct inode *inode)
1030{
1031	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1032	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1033	int rc;
1034
1035	rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1036				 inode);
1037	if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1038		return rc >= 0 ? -EINVAL : rc;
1039	rc = ecryptfs_validate_marker(marker);
1040	if (!rc)
1041		ecryptfs_i_size_init(file_size, inode);
1042	return rc;
1043}
1044
1045void
1046ecryptfs_write_header_metadata(char *virt,
1047			       struct ecryptfs_crypt_stat *crypt_stat,
1048			       size_t *written)
1049{
1050	u32 header_extent_size;
1051	u16 num_header_extents_at_front;
1052
1053	header_extent_size = (u32)crypt_stat->extent_size;
1054	num_header_extents_at_front =
1055		(u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1056	put_unaligned_be32(header_extent_size, virt);
1057	virt += 4;
1058	put_unaligned_be16(num_header_extents_at_front, virt);
1059	(*written) = 6;
1060}
1061
1062struct kmem_cache *ecryptfs_header_cache;
1063
1064/**
1065 * ecryptfs_write_headers_virt
1066 * @page_virt: The virtual address to write the headers to
1067 * @max: The size of memory allocated at page_virt
1068 * @size: Set to the number of bytes written by this function
1069 * @crypt_stat: The cryptographic context
1070 * @ecryptfs_dentry: The eCryptfs dentry
1071 *
1072 * Format version: 1
1073 *
1074 *   Header Extent:
1075 *     Octets 0-7:        Unencrypted file size (big-endian)
1076 *     Octets 8-15:       eCryptfs special marker
1077 *     Octets 16-19:      Flags
1078 *      Octet 16:         File format version number (between 0 and 255)
1079 *      Octets 17-18:     Reserved
1080 *      Octet 19:         Bit 1 (lsb): Reserved
1081 *                        Bit 2: Encrypted?
1082 *                        Bits 3-8: Reserved
1083 *     Octets 20-23:      Header extent size (big-endian)
1084 *     Octets 24-25:      Number of header extents at front of file
1085 *                        (big-endian)
1086 *     Octet  26:         Begin RFC 2440 authentication token packet set
1087 *   Data Extent 0:
1088 *     Lower data (CBC encrypted)
1089 *   Data Extent 1:
1090 *     Lower data (CBC encrypted)
1091 *   ...
1092 *
1093 * Returns zero on success
1094 */
1095static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1096				       size_t *size,
1097				       struct ecryptfs_crypt_stat *crypt_stat,
1098				       struct dentry *ecryptfs_dentry)
1099{
1100	int rc;
1101	size_t written;
1102	size_t offset;
1103
1104	offset = ECRYPTFS_FILE_SIZE_BYTES;
1105	write_ecryptfs_marker((page_virt + offset), &written);
1106	offset += written;
1107	ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1108					&written);
1109	offset += written;
1110	ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1111				       &written);
1112	offset += written;
1113	rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1114					      ecryptfs_dentry, &written,
1115					      max - offset);
1116	if (rc)
1117		ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1118				"set; rc = [%d]\n", rc);
1119	if (size) {
1120		offset += written;
1121		*size = offset;
1122	}
1123	return rc;
1124}
1125
1126static int
1127ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1128				    char *virt, size_t virt_len)
1129{
1130	int rc;
1131
1132	rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1133				  0, virt_len);
1134	if (rc < 0)
1135		printk(KERN_ERR "%s: Error attempting to write header "
1136		       "information to lower file; rc = [%d]\n", __func__, rc);
1137	else
1138		rc = 0;
1139	return rc;
1140}
1141
1142static int
1143ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
 
1144				 char *page_virt, size_t size)
1145{
1146	int rc;
1147
1148	rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1149			       size, 0);
1150	return rc;
1151}
1152
1153static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1154					       unsigned int order)
1155{
1156	struct page *page;
1157
1158	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1159	if (page)
1160		return (unsigned long) page_address(page);
1161	return 0;
1162}
1163
1164/**
1165 * ecryptfs_write_metadata
1166 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1167 * @ecryptfs_inode: The newly created eCryptfs inode
1168 *
1169 * Write the file headers out.  This will likely involve a userspace
1170 * callout, in which the session key is encrypted with one or more
1171 * public keys and/or the passphrase necessary to do the encryption is
1172 * retrieved via a prompt.  Exactly what happens at this point should
1173 * be policy-dependent.
1174 *
1175 * Returns zero on success; non-zero on error
1176 */
1177int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1178			    struct inode *ecryptfs_inode)
1179{
1180	struct ecryptfs_crypt_stat *crypt_stat =
1181		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1182	unsigned int order;
1183	char *virt;
1184	size_t virt_len;
1185	size_t size = 0;
1186	int rc = 0;
1187
1188	if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1189		if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1190			printk(KERN_ERR "Key is invalid; bailing out\n");
1191			rc = -EINVAL;
1192			goto out;
1193		}
1194	} else {
1195		printk(KERN_WARNING "%s: Encrypted flag not set\n",
1196		       __func__);
1197		rc = -EINVAL;
1198		goto out;
1199	}
1200	virt_len = crypt_stat->metadata_size;
1201	order = get_order(virt_len);
1202	/* Released in this function */
1203	virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1204	if (!virt) {
1205		printk(KERN_ERR "%s: Out of memory\n", __func__);
1206		rc = -ENOMEM;
1207		goto out;
1208	}
1209	/* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1210	rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1211					 ecryptfs_dentry);
1212	if (unlikely(rc)) {
1213		printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1214		       __func__, rc);
1215		goto out_free;
1216	}
1217	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1218		rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1219						      size);
1220	else
1221		rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1222							 virt_len);
1223	if (rc) {
1224		printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1225		       "rc = [%d]\n", __func__, rc);
1226		goto out_free;
1227	}
1228out_free:
1229	free_pages((unsigned long)virt, order);
1230out:
1231	return rc;
1232}
1233
1234#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1235#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1236static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1237				 char *virt, int *bytes_read,
1238				 int validate_header_size)
1239{
1240	int rc = 0;
1241	u32 header_extent_size;
1242	u16 num_header_extents_at_front;
1243
1244	header_extent_size = get_unaligned_be32(virt);
1245	virt += sizeof(__be32);
1246	num_header_extents_at_front = get_unaligned_be16(virt);
1247	crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1248				     * (size_t)header_extent_size));
1249	(*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1250	if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1251	    && (crypt_stat->metadata_size
1252		< ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1253		rc = -EINVAL;
1254		printk(KERN_WARNING "Invalid header size: [%zd]\n",
1255		       crypt_stat->metadata_size);
1256	}
1257	return rc;
1258}
1259
1260/**
1261 * set_default_header_data
1262 * @crypt_stat: The cryptographic context
1263 *
1264 * For version 0 file format; this function is only for backwards
1265 * compatibility for files created with the prior versions of
1266 * eCryptfs.
1267 */
1268static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1269{
1270	crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1271}
1272
1273void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1274{
1275	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1276	struct ecryptfs_crypt_stat *crypt_stat;
1277	u64 file_size;
1278
1279	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1280	mount_crypt_stat =
1281		&ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1282	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1283		file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1284		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1285			file_size += crypt_stat->metadata_size;
1286	} else
1287		file_size = get_unaligned_be64(page_virt);
1288	i_size_write(inode, (loff_t)file_size);
1289	crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1290}
1291
1292/**
1293 * ecryptfs_read_headers_virt
1294 * @page_virt: The virtual address into which to read the headers
1295 * @crypt_stat: The cryptographic context
1296 * @ecryptfs_dentry: The eCryptfs dentry
1297 * @validate_header_size: Whether to validate the header size while reading
1298 *
1299 * Read/parse the header data. The header format is detailed in the
1300 * comment block for the ecryptfs_write_headers_virt() function.
1301 *
1302 * Returns zero on success
1303 */
1304static int ecryptfs_read_headers_virt(char *page_virt,
1305				      struct ecryptfs_crypt_stat *crypt_stat,
1306				      struct dentry *ecryptfs_dentry,
1307				      int validate_header_size)
1308{
1309	int rc = 0;
1310	int offset;
1311	int bytes_read;
1312
1313	ecryptfs_set_default_sizes(crypt_stat);
1314	crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1315		ecryptfs_dentry->d_sb)->mount_crypt_stat;
1316	offset = ECRYPTFS_FILE_SIZE_BYTES;
1317	rc = ecryptfs_validate_marker(page_virt + offset);
1318	if (rc)
1319		goto out;
1320	if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1321		ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1322	offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1323	rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1324				    &bytes_read);
1325	if (rc) {
1326		ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1327		goto out;
1328	}
1329	if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1330		ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1331				"file version [%d] is supported by this "
1332				"version of eCryptfs\n",
1333				crypt_stat->file_version,
1334				ECRYPTFS_SUPPORTED_FILE_VERSION);
1335		rc = -EINVAL;
1336		goto out;
1337	}
1338	offset += bytes_read;
1339	if (crypt_stat->file_version >= 1) {
1340		rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1341					   &bytes_read, validate_header_size);
1342		if (rc) {
1343			ecryptfs_printk(KERN_WARNING, "Error reading header "
1344					"metadata; rc = [%d]\n", rc);
1345		}
1346		offset += bytes_read;
1347	} else
1348		set_default_header_data(crypt_stat);
1349	rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1350				       ecryptfs_dentry);
1351out:
1352	return rc;
1353}
1354
1355/**
1356 * ecryptfs_read_xattr_region
1357 * @page_virt: The vitual address into which to read the xattr data
1358 * @ecryptfs_inode: The eCryptfs inode
1359 *
1360 * Attempts to read the crypto metadata from the extended attribute
1361 * region of the lower file.
1362 *
1363 * Returns zero on success; non-zero on error
1364 */
1365int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1366{
1367	struct dentry *lower_dentry =
1368		ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1369	ssize_t size;
1370	int rc = 0;
1371
1372	size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
 
 
1373				       page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1374	if (size < 0) {
1375		if (unlikely(ecryptfs_verbosity > 0))
1376			printk(KERN_INFO "Error attempting to read the [%s] "
1377			       "xattr from the lower file; return value = "
1378			       "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1379		rc = -EINVAL;
1380		goto out;
1381	}
1382out:
1383	return rc;
1384}
1385
1386int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1387					    struct inode *inode)
1388{
1389	u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1390	u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1391	int rc;
1392
1393	rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
 
1394				     ECRYPTFS_XATTR_NAME, file_size,
1395				     ECRYPTFS_SIZE_AND_MARKER_BYTES);
1396	if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1397		return rc >= 0 ? -EINVAL : rc;
1398	rc = ecryptfs_validate_marker(marker);
1399	if (!rc)
1400		ecryptfs_i_size_init(file_size, inode);
1401	return rc;
1402}
1403
1404/**
1405 * ecryptfs_read_metadata
1406 *
1407 * Common entry point for reading file metadata. From here, we could
1408 * retrieve the header information from the header region of the file,
1409 * the xattr region of the file, or some other repostory that is
1410 * stored separately from the file itself. The current implementation
1411 * supports retrieving the metadata information from the file contents
1412 * and from the xattr region.
1413 *
1414 * Returns zero if valid headers found and parsed; non-zero otherwise
1415 */
1416int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1417{
1418	int rc;
1419	char *page_virt;
1420	struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1421	struct ecryptfs_crypt_stat *crypt_stat =
1422	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1423	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1424		&ecryptfs_superblock_to_private(
1425			ecryptfs_dentry->d_sb)->mount_crypt_stat;
1426
1427	ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1428						      mount_crypt_stat);
1429	/* Read the first page from the underlying file */
1430	page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1431	if (!page_virt) {
1432		rc = -ENOMEM;
1433		printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1434		       __func__);
1435		goto out;
1436	}
1437	rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1438				 ecryptfs_inode);
1439	if (rc >= 0)
1440		rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1441						ecryptfs_dentry,
1442						ECRYPTFS_VALIDATE_HEADER_SIZE);
1443	if (rc) {
1444		/* metadata is not in the file header, so try xattrs */
1445		memset(page_virt, 0, PAGE_SIZE);
1446		rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1447		if (rc) {
1448			printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1449			       "file header region or xattr region, inode %lu\n",
1450				ecryptfs_inode->i_ino);
1451			rc = -EINVAL;
1452			goto out;
1453		}
1454		rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1455						ecryptfs_dentry,
1456						ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1457		if (rc) {
1458			printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1459			       "file xattr region either, inode %lu\n",
1460				ecryptfs_inode->i_ino);
1461			rc = -EINVAL;
1462		}
1463		if (crypt_stat->mount_crypt_stat->flags
1464		    & ECRYPTFS_XATTR_METADATA_ENABLED) {
1465			crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1466		} else {
1467			printk(KERN_WARNING "Attempt to access file with "
1468			       "crypto metadata only in the extended attribute "
1469			       "region, but eCryptfs was mounted without "
1470			       "xattr support enabled. eCryptfs will not treat "
1471			       "this like an encrypted file, inode %lu\n",
1472				ecryptfs_inode->i_ino);
1473			rc = -EINVAL;
1474		}
1475	}
1476out:
1477	if (page_virt) {
1478		memset(page_virt, 0, PAGE_SIZE);
1479		kmem_cache_free(ecryptfs_header_cache, page_virt);
1480	}
1481	return rc;
1482}
1483
1484/**
1485 * ecryptfs_encrypt_filename - encrypt filename
1486 *
1487 * CBC-encrypts the filename. We do not want to encrypt the same
1488 * filename with the same key and IV, which may happen with hard
1489 * links, so we prepend random bits to each filename.
1490 *
1491 * Returns zero on success; non-zero otherwise
1492 */
1493static int
1494ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1495			  struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1496{
1497	int rc = 0;
1498
1499	filename->encrypted_filename = NULL;
1500	filename->encrypted_filename_size = 0;
1501	if (mount_crypt_stat && (mount_crypt_stat->flags
1502				     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1503		size_t packet_size;
1504		size_t remaining_bytes;
1505
1506		rc = ecryptfs_write_tag_70_packet(
1507			NULL, NULL,
1508			&filename->encrypted_filename_size,
1509			mount_crypt_stat, NULL,
1510			filename->filename_size);
1511		if (rc) {
1512			printk(KERN_ERR "%s: Error attempting to get packet "
1513			       "size for tag 72; rc = [%d]\n", __func__,
1514			       rc);
1515			filename->encrypted_filename_size = 0;
1516			goto out;
1517		}
1518		filename->encrypted_filename =
1519			kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1520		if (!filename->encrypted_filename) {
1521			printk(KERN_ERR "%s: Out of memory whilst attempting "
1522			       "to kmalloc [%zd] bytes\n", __func__,
1523			       filename->encrypted_filename_size);
1524			rc = -ENOMEM;
1525			goto out;
1526		}
1527		remaining_bytes = filename->encrypted_filename_size;
1528		rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1529						  &remaining_bytes,
1530						  &packet_size,
1531						  mount_crypt_stat,
1532						  filename->filename,
1533						  filename->filename_size);
1534		if (rc) {
1535			printk(KERN_ERR "%s: Error attempting to generate "
1536			       "tag 70 packet; rc = [%d]\n", __func__,
1537			       rc);
1538			kfree(filename->encrypted_filename);
1539			filename->encrypted_filename = NULL;
1540			filename->encrypted_filename_size = 0;
1541			goto out;
1542		}
1543		filename->encrypted_filename_size = packet_size;
1544	} else {
1545		printk(KERN_ERR "%s: No support for requested filename "
1546		       "encryption method in this release\n", __func__);
1547		rc = -EOPNOTSUPP;
1548		goto out;
1549	}
1550out:
1551	return rc;
1552}
1553
1554static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1555				  const char *name, size_t name_size)
1556{
1557	int rc = 0;
1558
1559	(*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1560	if (!(*copied_name)) {
1561		rc = -ENOMEM;
1562		goto out;
1563	}
1564	memcpy((void *)(*copied_name), (void *)name, name_size);
1565	(*copied_name)[(name_size)] = '\0';	/* Only for convenience
1566						 * in printing out the
1567						 * string in debug
1568						 * messages */
1569	(*copied_name_size) = name_size;
1570out:
1571	return rc;
1572}
1573
1574/**
1575 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1576 * @key_tfm: Crypto context for key material, set by this function
1577 * @cipher_name: Name of the cipher
1578 * @key_size: Size of the key in bytes
1579 *
1580 * Returns zero on success. Any crypto_tfm structs allocated here
1581 * should be released by other functions, such as on a superblock put
1582 * event, regardless of whether this function succeeds for fails.
1583 */
1584static int
1585ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1586			    char *cipher_name, size_t *key_size)
1587{
1588	char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1589	char *full_alg_name = NULL;
1590	int rc;
1591
1592	*key_tfm = NULL;
1593	if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1594		rc = -EINVAL;
1595		printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1596		      "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1597		goto out;
1598	}
1599	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1600						    "ecb");
1601	if (rc)
1602		goto out;
1603	*key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1604	if (IS_ERR(*key_tfm)) {
1605		rc = PTR_ERR(*key_tfm);
1606		printk(KERN_ERR "Unable to allocate crypto cipher with name "
1607		       "[%s]; rc = [%d]\n", full_alg_name, rc);
1608		goto out;
1609	}
1610	crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1611	if (*key_size == 0)
1612		*key_size = crypto_skcipher_default_keysize(*key_tfm);
1613	get_random_bytes(dummy_key, *key_size);
1614	rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1615	if (rc) {
1616		printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1617		       "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1618		       rc);
1619		rc = -EINVAL;
1620		goto out;
1621	}
1622out:
1623	kfree(full_alg_name);
1624	return rc;
1625}
1626
1627struct kmem_cache *ecryptfs_key_tfm_cache;
1628static struct list_head key_tfm_list;
1629struct mutex key_tfm_list_mutex;
1630
1631int __init ecryptfs_init_crypto(void)
1632{
1633	mutex_init(&key_tfm_list_mutex);
1634	INIT_LIST_HEAD(&key_tfm_list);
1635	return 0;
1636}
1637
1638/**
1639 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1640 *
1641 * Called only at module unload time
1642 */
1643int ecryptfs_destroy_crypto(void)
1644{
1645	struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1646
1647	mutex_lock(&key_tfm_list_mutex);
1648	list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1649				 key_tfm_list) {
1650		list_del(&key_tfm->key_tfm_list);
1651		crypto_free_skcipher(key_tfm->key_tfm);
1652		kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1653	}
1654	mutex_unlock(&key_tfm_list_mutex);
1655	return 0;
1656}
1657
1658int
1659ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1660			 size_t key_size)
1661{
1662	struct ecryptfs_key_tfm *tmp_tfm;
1663	int rc = 0;
1664
1665	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1666
1667	tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1668	if (key_tfm != NULL)
1669		(*key_tfm) = tmp_tfm;
1670	if (!tmp_tfm) {
1671		rc = -ENOMEM;
1672		printk(KERN_ERR "Error attempting to allocate from "
1673		       "ecryptfs_key_tfm_cache\n");
1674		goto out;
1675	}
1676	mutex_init(&tmp_tfm->key_tfm_mutex);
1677	strncpy(tmp_tfm->cipher_name, cipher_name,
1678		ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1679	tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1680	tmp_tfm->key_size = key_size;
1681	rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1682					 tmp_tfm->cipher_name,
1683					 &tmp_tfm->key_size);
1684	if (rc) {
1685		printk(KERN_ERR "Error attempting to initialize key TFM "
1686		       "cipher with name = [%s]; rc = [%d]\n",
1687		       tmp_tfm->cipher_name, rc);
1688		kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1689		if (key_tfm != NULL)
1690			(*key_tfm) = NULL;
1691		goto out;
1692	}
1693	list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1694out:
1695	return rc;
1696}
1697
1698/**
1699 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1700 * @cipher_name: the name of the cipher to search for
1701 * @key_tfm: set to corresponding tfm if found
1702 *
1703 * Searches for cached key_tfm matching @cipher_name
1704 * Must be called with &key_tfm_list_mutex held
1705 * Returns 1 if found, with @key_tfm set
1706 * Returns 0 if not found, with @key_tfm set to NULL
1707 */
1708int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1709{
1710	struct ecryptfs_key_tfm *tmp_key_tfm;
1711
1712	BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1713
1714	list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1715		if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1716			if (key_tfm)
1717				(*key_tfm) = tmp_key_tfm;
1718			return 1;
1719		}
1720	}
1721	if (key_tfm)
1722		(*key_tfm) = NULL;
1723	return 0;
1724}
1725
1726/**
1727 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1728 *
1729 * @tfm: set to cached tfm found, or new tfm created
1730 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1731 * @cipher_name: the name of the cipher to search for and/or add
1732 *
1733 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1734 * Searches for cached item first, and creates new if not found.
1735 * Returns 0 on success, non-zero if adding new cipher failed
1736 */
1737int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1738					       struct mutex **tfm_mutex,
1739					       char *cipher_name)
1740{
1741	struct ecryptfs_key_tfm *key_tfm;
1742	int rc = 0;
1743
1744	(*tfm) = NULL;
1745	(*tfm_mutex) = NULL;
1746
1747	mutex_lock(&key_tfm_list_mutex);
1748	if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1749		rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1750		if (rc) {
1751			printk(KERN_ERR "Error adding new key_tfm to list; "
1752					"rc = [%d]\n", rc);
1753			goto out;
1754		}
1755	}
1756	(*tfm) = key_tfm->key_tfm;
1757	(*tfm_mutex) = &key_tfm->key_tfm_mutex;
1758out:
1759	mutex_unlock(&key_tfm_list_mutex);
1760	return rc;
1761}
1762
1763/* 64 characters forming a 6-bit target field */
1764static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1765						 "EFGHIJKLMNOPQRST"
1766						 "UVWXYZabcdefghij"
1767						 "klmnopqrstuvwxyz");
1768
1769/* We could either offset on every reverse map or just pad some 0x00's
1770 * at the front here */
1771static const unsigned char filename_rev_map[256] = {
1772	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1773	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1774	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1775	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1776	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1777	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1778	0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1779	0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1780	0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1781	0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1782	0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1783	0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1784	0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1785	0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1786	0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1787	0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1788};
1789
1790/**
1791 * ecryptfs_encode_for_filename
1792 * @dst: Destination location for encoded filename
1793 * @dst_size: Size of the encoded filename in bytes
1794 * @src: Source location for the filename to encode
1795 * @src_size: Size of the source in bytes
1796 */
1797static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1798				  unsigned char *src, size_t src_size)
1799{
1800	size_t num_blocks;
1801	size_t block_num = 0;
1802	size_t dst_offset = 0;
1803	unsigned char last_block[3];
1804
1805	if (src_size == 0) {
1806		(*dst_size) = 0;
1807		goto out;
1808	}
1809	num_blocks = (src_size / 3);
1810	if ((src_size % 3) == 0) {
1811		memcpy(last_block, (&src[src_size - 3]), 3);
1812	} else {
1813		num_blocks++;
1814		last_block[2] = 0x00;
1815		switch (src_size % 3) {
1816		case 1:
1817			last_block[0] = src[src_size - 1];
1818			last_block[1] = 0x00;
1819			break;
1820		case 2:
1821			last_block[0] = src[src_size - 2];
1822			last_block[1] = src[src_size - 1];
1823		}
1824	}
1825	(*dst_size) = (num_blocks * 4);
1826	if (!dst)
1827		goto out;
1828	while (block_num < num_blocks) {
1829		unsigned char *src_block;
1830		unsigned char dst_block[4];
1831
1832		if (block_num == (num_blocks - 1))
1833			src_block = last_block;
1834		else
1835			src_block = &src[block_num * 3];
1836		dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1837		dst_block[1] = (((src_block[0] << 4) & 0x30)
1838				| ((src_block[1] >> 4) & 0x0F));
1839		dst_block[2] = (((src_block[1] << 2) & 0x3C)
1840				| ((src_block[2] >> 6) & 0x03));
1841		dst_block[3] = (src_block[2] & 0x3F);
1842		dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1843		dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1844		dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1845		dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1846		block_num++;
1847	}
1848out:
1849	return;
1850}
1851
1852static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1853{
1854	/* Not exact; conservatively long. Every block of 4
1855	 * encoded characters decodes into a block of 3
1856	 * decoded characters. This segment of code provides
1857	 * the caller with the maximum amount of allocated
1858	 * space that @dst will need to point to in a
1859	 * subsequent call. */
1860	return ((encoded_size + 1) * 3) / 4;
1861}
1862
1863/**
1864 * ecryptfs_decode_from_filename
1865 * @dst: If NULL, this function only sets @dst_size and returns. If
1866 *       non-NULL, this function decodes the encoded octets in @src
1867 *       into the memory that @dst points to.
1868 * @dst_size: Set to the size of the decoded string.
1869 * @src: The encoded set of octets to decode.
1870 * @src_size: The size of the encoded set of octets to decode.
1871 */
1872static void
1873ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1874			      const unsigned char *src, size_t src_size)
1875{
1876	u8 current_bit_offset = 0;
1877	size_t src_byte_offset = 0;
1878	size_t dst_byte_offset = 0;
1879
1880	if (dst == NULL) {
1881		(*dst_size) = ecryptfs_max_decoded_size(src_size);
1882		goto out;
1883	}
1884	while (src_byte_offset < src_size) {
1885		unsigned char src_byte =
1886				filename_rev_map[(int)src[src_byte_offset]];
1887
1888		switch (current_bit_offset) {
1889		case 0:
1890			dst[dst_byte_offset] = (src_byte << 2);
1891			current_bit_offset = 6;
1892			break;
1893		case 6:
1894			dst[dst_byte_offset++] |= (src_byte >> 4);
1895			dst[dst_byte_offset] = ((src_byte & 0xF)
1896						 << 4);
1897			current_bit_offset = 4;
1898			break;
1899		case 4:
1900			dst[dst_byte_offset++] |= (src_byte >> 2);
1901			dst[dst_byte_offset] = (src_byte << 6);
1902			current_bit_offset = 2;
1903			break;
1904		case 2:
1905			dst[dst_byte_offset++] |= (src_byte);
1906			current_bit_offset = 0;
1907			break;
1908		}
1909		src_byte_offset++;
1910	}
1911	(*dst_size) = dst_byte_offset;
1912out:
1913	return;
1914}
1915
1916/**
1917 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1918 * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1919 * @name: The plaintext name
1920 * @length: The length of the plaintext
1921 * @encoded_name: The encypted name
1922 *
1923 * Encrypts and encodes a filename into something that constitutes a
1924 * valid filename for a filesystem, with printable characters.
1925 *
1926 * We assume that we have a properly initialized crypto context,
1927 * pointed to by crypt_stat->tfm.
1928 *
1929 * Returns zero on success; non-zero on otherwise
1930 */
1931int ecryptfs_encrypt_and_encode_filename(
1932	char **encoded_name,
1933	size_t *encoded_name_size,
1934	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1935	const char *name, size_t name_size)
1936{
1937	size_t encoded_name_no_prefix_size;
1938	int rc = 0;
1939
1940	(*encoded_name) = NULL;
1941	(*encoded_name_size) = 0;
1942	if (mount_crypt_stat && (mount_crypt_stat->flags
1943				     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1944		struct ecryptfs_filename *filename;
1945
1946		filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1947		if (!filename) {
1948			printk(KERN_ERR "%s: Out of memory whilst attempting "
1949			       "to kzalloc [%zd] bytes\n", __func__,
1950			       sizeof(*filename));
1951			rc = -ENOMEM;
1952			goto out;
1953		}
1954		filename->filename = (char *)name;
1955		filename->filename_size = name_size;
1956		rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1957		if (rc) {
1958			printk(KERN_ERR "%s: Error attempting to encrypt "
1959			       "filename; rc = [%d]\n", __func__, rc);
1960			kfree(filename);
1961			goto out;
1962		}
1963		ecryptfs_encode_for_filename(
1964			NULL, &encoded_name_no_prefix_size,
1965			filename->encrypted_filename,
1966			filename->encrypted_filename_size);
1967		if (mount_crypt_stat
1968			&& (mount_crypt_stat->flags
1969			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1970			(*encoded_name_size) =
1971				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1972				 + encoded_name_no_prefix_size);
1973		else
1974			(*encoded_name_size) =
1975				(ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1976				 + encoded_name_no_prefix_size);
1977		(*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1978		if (!(*encoded_name)) {
1979			printk(KERN_ERR "%s: Out of memory whilst attempting "
1980			       "to kzalloc [%zd] bytes\n", __func__,
1981			       (*encoded_name_size));
1982			rc = -ENOMEM;
1983			kfree(filename->encrypted_filename);
1984			kfree(filename);
1985			goto out;
1986		}
1987		if (mount_crypt_stat
1988			&& (mount_crypt_stat->flags
1989			    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1990			memcpy((*encoded_name),
1991			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1992			       ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1993			ecryptfs_encode_for_filename(
1994			    ((*encoded_name)
1995			     + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1996			    &encoded_name_no_prefix_size,
1997			    filename->encrypted_filename,
1998			    filename->encrypted_filename_size);
1999			(*encoded_name_size) =
2000				(ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2001				 + encoded_name_no_prefix_size);
2002			(*encoded_name)[(*encoded_name_size)] = '\0';
2003		} else {
2004			rc = -EOPNOTSUPP;
2005		}
2006		if (rc) {
2007			printk(KERN_ERR "%s: Error attempting to encode "
2008			       "encrypted filename; rc = [%d]\n", __func__,
2009			       rc);
2010			kfree((*encoded_name));
2011			(*encoded_name) = NULL;
2012			(*encoded_name_size) = 0;
2013		}
2014		kfree(filename->encrypted_filename);
2015		kfree(filename);
2016	} else {
2017		rc = ecryptfs_copy_filename(encoded_name,
2018					    encoded_name_size,
2019					    name, name_size);
2020	}
2021out:
2022	return rc;
2023}
2024
 
 
 
 
 
 
 
 
 
 
2025/**
2026 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2027 * @plaintext_name: The plaintext name
2028 * @plaintext_name_size: The plaintext name size
2029 * @ecryptfs_dir_dentry: eCryptfs directory dentry
2030 * @name: The filename in cipher text
2031 * @name_size: The cipher text name size
2032 *
2033 * Decrypts and decodes the filename.
2034 *
2035 * Returns zero on error; non-zero otherwise
2036 */
2037int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2038					 size_t *plaintext_name_size,
2039					 struct super_block *sb,
2040					 const char *name, size_t name_size)
2041{
2042	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2043		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2044	char *decoded_name;
2045	size_t decoded_name_size;
2046	size_t packet_size;
2047	int rc = 0;
2048
2049	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2050	    && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2051	    && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2052	    && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2053			ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2054		const char *orig_name = name;
2055		size_t orig_name_size = name_size;
 
 
 
 
 
 
 
 
2056
2057		name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2058		name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2059		ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2060					      name, name_size);
2061		decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2062		if (!decoded_name) {
2063			printk(KERN_ERR "%s: Out of memory whilst attempting "
2064			       "to kmalloc [%zd] bytes\n", __func__,
2065			       decoded_name_size);
2066			rc = -ENOMEM;
2067			goto out;
2068		}
2069		ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2070					      name, name_size);
2071		rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2072						  plaintext_name_size,
2073						  &packet_size,
2074						  mount_crypt_stat,
2075						  decoded_name,
2076						  decoded_name_size);
2077		if (rc) {
2078			printk(KERN_INFO "%s: Could not parse tag 70 packet "
2079			       "from filename; copying through filename "
2080			       "as-is\n", __func__);
2081			rc = ecryptfs_copy_filename(plaintext_name,
2082						    plaintext_name_size,
2083						    orig_name, orig_name_size);
2084			goto out_free;
2085		}
2086	} else {
2087		rc = ecryptfs_copy_filename(plaintext_name,
2088					    plaintext_name_size,
2089					    name, name_size);
2090		goto out;
2091	}
2092out_free:
2093	kfree(decoded_name);
2094out:
2095	return rc;
2096}
2097
2098#define ENC_NAME_MAX_BLOCKLEN_8_OR_16	143
2099
2100int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2101			   struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2102{
2103	struct crypto_skcipher *tfm;
2104	struct mutex *tfm_mutex;
2105	size_t cipher_blocksize;
2106	int rc;
2107
2108	if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2109		(*namelen) = lower_namelen;
2110		return 0;
2111	}
2112
2113	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2114			mount_crypt_stat->global_default_fn_cipher_name);
2115	if (unlikely(rc)) {
2116		(*namelen) = 0;
2117		return rc;
2118	}
2119
2120	mutex_lock(tfm_mutex);
2121	cipher_blocksize = crypto_skcipher_blocksize(tfm);
2122	mutex_unlock(tfm_mutex);
2123
2124	/* Return an exact amount for the common cases */
2125	if (lower_namelen == NAME_MAX
2126	    && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2127		(*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2128		return 0;
2129	}
2130
2131	/* Return a safe estimate for the uncommon cases */
2132	(*namelen) = lower_namelen;
2133	(*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2134	/* Since this is the max decoded size, subtract 1 "decoded block" len */
2135	(*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2136	(*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2137	(*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2138	/* Worst case is that the filename is padded nearly a full block size */
2139	(*namelen) -= cipher_blocksize - 1;
2140
2141	if ((*namelen) < 0)
2142		(*namelen) = 0;
2143
2144	return 0;
2145}