linux/fs/ecryptfs/crypto.c
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   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 <linux/fs.h>
  27#include <linux/mount.h>
  28#include <linux/pagemap.h>
  29#include <linux/random.h>
  30#include <linux/compiler.h>
  31#include <linux/key.h>
  32#include <linux/namei.h>
  33#include <linux/crypto.h>
  34#include <linux/file.h>
  35#include <linux/scatterlist.h>
  36#include <linux/slab.h>
  37#include <asm/unaligned.h>
  38#include "ecryptfs_kernel.h"
  39
  40#define DECRYPT         0
  41#define ENCRYPT         1
  42
  43/**
  44 * ecryptfs_to_hex
  45 * @dst: Buffer to take hex character representation of contents of
  46 *       src; must be at least of size (src_size * 2)
  47 * @src: Buffer to be converted to a hex string respresentation
  48 * @src_size: number of bytes to convert
  49 */
  50void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
  51{
  52        int x;
  53
  54        for (x = 0; x < src_size; x++)
  55                sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
  56}
  57
  58/**
  59 * ecryptfs_from_hex
  60 * @dst: Buffer to take the bytes from src hex; must be at least of
  61 *       size (src_size / 2)
  62 * @src: Buffer to be converted from a hex string respresentation to raw value
  63 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  64 */
  65void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  66{
  67        int x;
  68        char tmp[3] = { 0, };
  69
  70        for (x = 0; x < dst_size; x++) {
  71                tmp[0] = src[x * 2];
  72                tmp[1] = src[x * 2 + 1];
  73                dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  74        }
  75}
  76
  77/**
  78 * ecryptfs_calculate_md5 - calculates the md5 of @src
  79 * @dst: Pointer to 16 bytes of allocated memory
  80 * @crypt_stat: Pointer to crypt_stat struct for the current inode
  81 * @src: Data to be md5'd
  82 * @len: Length of @src
  83 *
  84 * Uses the allocated crypto context that crypt_stat references to
  85 * generate the MD5 sum of the contents of src.
  86 */
  87static int ecryptfs_calculate_md5(char *dst,
  88                                  struct ecryptfs_crypt_stat *crypt_stat,
  89                                  char *src, int len)
  90{
  91        struct scatterlist sg;
  92        struct hash_desc desc = {
  93                .tfm = crypt_stat->hash_tfm,
  94                .flags = CRYPTO_TFM_REQ_MAY_SLEEP
  95        };
  96        int rc = 0;
  97
  98        mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
  99        sg_init_one(&sg, (u8 *)src, len);
 100        if (!desc.tfm) {
 101                desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
 102                                             CRYPTO_ALG_ASYNC);
 103                if (IS_ERR(desc.tfm)) {
 104                        rc = PTR_ERR(desc.tfm);
 105                        ecryptfs_printk(KERN_ERR, "Error attempting to "
 106                                        "allocate crypto context; rc = [%d]\n",
 107                                        rc);
 108                        goto out;
 109                }
 110                crypt_stat->hash_tfm = desc.tfm;
 111        }
 112        rc = crypto_hash_init(&desc);
 113        if (rc) {
 114                printk(KERN_ERR
 115                       "%s: Error initializing crypto hash; rc = [%d]\n",
 116                       __func__, rc);
 117                goto out;
 118        }
 119        rc = crypto_hash_update(&desc, &sg, len);
 120        if (rc) {
 121                printk(KERN_ERR
 122                       "%s: Error updating crypto hash; rc = [%d]\n",
 123                       __func__, rc);
 124                goto out;
 125        }
 126        rc = crypto_hash_final(&desc, dst);
 127        if (rc) {
 128                printk(KERN_ERR
 129                       "%s: Error finalizing crypto hash; rc = [%d]\n",
 130                       __func__, rc);
 131                goto out;
 132        }
 133out:
 134        mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
 135        return rc;
 136}
 137
 138static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
 139                                                  char *cipher_name,
 140                                                  char *chaining_modifier)
 141{
 142        int cipher_name_len = strlen(cipher_name);
 143        int chaining_modifier_len = strlen(chaining_modifier);
 144        int algified_name_len;
 145        int rc;
 146
 147        algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
 148        (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
 149        if (!(*algified_name)) {
 150                rc = -ENOMEM;
 151                goto out;
 152        }
 153        snprintf((*algified_name), algified_name_len, "%s(%s)",
 154                 chaining_modifier, cipher_name);
 155        rc = 0;
 156out:
 157        return rc;
 158}
 159
 160/**
 161 * ecryptfs_derive_iv
 162 * @iv: destination for the derived iv vale
 163 * @crypt_stat: Pointer to crypt_stat struct for the current inode
 164 * @offset: Offset of the extent whose IV we are to derive
 165 *
 166 * Generate the initialization vector from the given root IV and page
 167 * offset.
 168 *
 169 * Returns zero on success; non-zero on error.
 170 */
 171int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 172                       loff_t offset)
 173{
 174        int rc = 0;
 175        char dst[MD5_DIGEST_SIZE];
 176        char src[ECRYPTFS_MAX_IV_BYTES + 16];
 177
 178        if (unlikely(ecryptfs_verbosity > 0)) {
 179                ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 180                ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 181        }
 182        /* TODO: It is probably secure to just cast the least
 183         * significant bits of the root IV into an unsigned long and
 184         * add the offset to that rather than go through all this
 185         * hashing business. -Halcrow */
 186        memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 187        memset((src + crypt_stat->iv_bytes), 0, 16);
 188        snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
 189        if (unlikely(ecryptfs_verbosity > 0)) {
 190                ecryptfs_printk(KERN_DEBUG, "source:\n");
 191                ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 192        }
 193        rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 194                                    (crypt_stat->iv_bytes + 16));
 195        if (rc) {
 196                ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 197                                "MD5 while generating IV for a page\n");
 198                goto out;
 199        }
 200        memcpy(iv, dst, crypt_stat->iv_bytes);
 201        if (unlikely(ecryptfs_verbosity > 0)) {
 202                ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 203                ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 204        }
 205out:
 206        return rc;
 207}
 208
 209/**
 210 * ecryptfs_init_crypt_stat
 211 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 212 *
 213 * Initialize the crypt_stat structure.
 214 */
 215void
 216ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 217{
 218        memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 219        INIT_LIST_HEAD(&crypt_stat->keysig_list);
 220        mutex_init(&crypt_stat->keysig_list_mutex);
 221        mutex_init(&crypt_stat->cs_mutex);
 222        mutex_init(&crypt_stat->cs_tfm_mutex);
 223        mutex_init(&crypt_stat->cs_hash_tfm_mutex);
 224        crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 225}
 226
 227/**
 228 * ecryptfs_destroy_crypt_stat
 229 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 230 *
 231 * Releases all memory associated with a crypt_stat struct.
 232 */
 233void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 234{
 235        struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 236
 237        if (crypt_stat->tfm)
 238                crypto_free_ablkcipher(crypt_stat->tfm);
 239        if (crypt_stat->hash_tfm)
 240                crypto_free_hash(crypt_stat->hash_tfm);
 241        list_for_each_entry_safe(key_sig, key_sig_tmp,
 242                                 &crypt_stat->keysig_list, crypt_stat_list) {
 243                list_del(&key_sig->crypt_stat_list);
 244                kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 245        }
 246        memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 247}
 248
 249void ecryptfs_destroy_mount_crypt_stat(
 250        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 251{
 252        struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 253
 254        if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 255                return;
 256        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 257        list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 258                                 &mount_crypt_stat->global_auth_tok_list,
 259                                 mount_crypt_stat_list) {
 260                list_del(&auth_tok->mount_crypt_stat_list);
 261                if (auth_tok->global_auth_tok_key
 262                    && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 263                        key_put(auth_tok->global_auth_tok_key);
 264                kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 265        }
 266        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 267        memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 268}
 269
 270/**
 271 * virt_to_scatterlist
 272 * @addr: Virtual address
 273 * @size: Size of data; should be an even multiple of the block size
 274 * @sg: Pointer to scatterlist array; set to NULL to obtain only
 275 *      the number of scatterlist structs required in array
 276 * @sg_size: Max array size
 277 *
 278 * Fills in a scatterlist array with page references for a passed
 279 * virtual address.
 280 *
 281 * Returns the number of scatterlist structs in array used
 282 */
 283int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 284                        int sg_size)
 285{
 286        int i = 0;
 287        struct page *pg;
 288        int offset;
 289        int remainder_of_page;
 290
 291        sg_init_table(sg, sg_size);
 292
 293        while (size > 0 && i < sg_size) {
 294                pg = virt_to_page(addr);
 295                offset = offset_in_page(addr);
 296                sg_set_page(&sg[i], pg, 0, offset);
 297                remainder_of_page = PAGE_CACHE_SIZE - offset;
 298                if (size >= remainder_of_page) {
 299                        sg[i].length = remainder_of_page;
 300                        addr += remainder_of_page;
 301                        size -= remainder_of_page;
 302                } else {
 303                        sg[i].length = size;
 304                        addr += size;
 305                        size = 0;
 306                }
 307                i++;
 308        }
 309        if (size > 0)
 310                return -ENOMEM;
 311        return i;
 312}
 313
 314struct extent_crypt_result {
 315        struct completion completion;
 316        int rc;
 317};
 318
 319static void extent_crypt_complete(struct crypto_async_request *req, int rc)
 320{
 321        struct extent_crypt_result *ecr = req->data;
 322
 323        if (rc == -EINPROGRESS)
 324                return;
 325
 326        ecr->rc = rc;
 327        complete(&ecr->completion);
 328}
 329
 330/**
 331 * crypt_scatterlist
 332 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 333 * @dst_sg: Destination of the data after performing the crypto operation
 334 * @src_sg: Data to be encrypted or decrypted
 335 * @size: Length of data
 336 * @iv: IV to use
 337 * @op: ENCRYPT or DECRYPT to indicate the desired operation
 338 *
 339 * Returns the number of bytes encrypted or decrypted; negative value on error
 340 */
 341static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 342                             struct scatterlist *dst_sg,
 343                             struct scatterlist *src_sg, int size,
 344                             unsigned char *iv, int op)
 345{
 346        struct ablkcipher_request *req = NULL;
 347        struct extent_crypt_result ecr;
 348        int rc = 0;
 349
 350        BUG_ON(!crypt_stat || !crypt_stat->tfm
 351               || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 352        if (unlikely(ecryptfs_verbosity > 0)) {
 353                ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 354                                crypt_stat->key_size);
 355                ecryptfs_dump_hex(crypt_stat->key,
 356                                  crypt_stat->key_size);
 357        }
 358
 359        init_completion(&ecr.completion);
 360
 361        mutex_lock(&crypt_stat->cs_tfm_mutex);
 362        req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
 363        if (!req) {
 364                mutex_unlock(&crypt_stat->cs_tfm_mutex);
 365                rc = -ENOMEM;
 366                goto out;
 367        }
 368
 369        ablkcipher_request_set_callback(req,
 370                        CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 371                        extent_crypt_complete, &ecr);
 372        /* Consider doing this once, when the file is opened */
 373        if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 374                rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 375                                              crypt_stat->key_size);
 376                if (rc) {
 377                        ecryptfs_printk(KERN_ERR,
 378                                        "Error setting key; rc = [%d]\n",
 379                                        rc);
 380                        mutex_unlock(&crypt_stat->cs_tfm_mutex);
 381                        rc = -EINVAL;
 382                        goto out;
 383                }
 384                crypt_stat->flags |= ECRYPTFS_KEY_SET;
 385        }
 386        mutex_unlock(&crypt_stat->cs_tfm_mutex);
 387        ablkcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 388        rc = op == ENCRYPT ? crypto_ablkcipher_encrypt(req) :
 389                             crypto_ablkcipher_decrypt(req);
 390        if (rc == -EINPROGRESS || rc == -EBUSY) {
 391                struct extent_crypt_result *ecr = req->base.data;
 392
 393                wait_for_completion(&ecr->completion);
 394                rc = ecr->rc;
 395                INIT_COMPLETION(ecr->completion);
 396        }
 397out:
 398        ablkcipher_request_free(req);
 399        return rc;
 400}
 401
 402/**
 403 * lower_offset_for_page
 404 *
 405 * Convert an eCryptfs page index into a lower byte offset
 406 */
 407static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 408                                    struct page *page)
 409{
 410        return ecryptfs_lower_header_size(crypt_stat) +
 411               (page->index << PAGE_CACHE_SHIFT);
 412}
 413
 414/**
 415 * crypt_extent
 416 * @crypt_stat: crypt_stat containing cryptographic context for the
 417 *              encryption operation
 418 * @dst_page: The page to write the result into
 419 * @src_page: The page to read from
 420 * @extent_offset: Page extent offset for use in generating IV
 421 * @op: ENCRYPT or DECRYPT to indicate the desired operation
 422 *
 423 * Encrypts or decrypts one extent of data.
 424 *
 425 * Return zero on success; non-zero otherwise
 426 */
 427static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 428                        struct page *dst_page,
 429                        struct page *src_page,
 430                        unsigned long extent_offset, int op)
 431{
 432        pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
 433        loff_t extent_base;
 434        char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 435        struct scatterlist src_sg, dst_sg;
 436        size_t extent_size = crypt_stat->extent_size;
 437        int rc;
 438
 439        extent_base = (((loff_t)page_index) * (PAGE_CACHE_SIZE / extent_size));
 440        rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 441                                (extent_base + extent_offset));
 442        if (rc) {
 443                ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 444                        "extent [0x%.16llx]; rc = [%d]\n",
 445                        (unsigned long long)(extent_base + extent_offset), rc);
 446                goto out;
 447        }
 448
 449        sg_init_table(&src_sg, 1);
 450        sg_init_table(&dst_sg, 1);
 451
 452        sg_set_page(&src_sg, src_page, extent_size,
 453                    extent_offset * extent_size);
 454        sg_set_page(&dst_sg, dst_page, extent_size,
 455                    extent_offset * extent_size);
 456
 457        rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 458                               extent_iv, op);
 459        if (rc < 0) {
 460                printk(KERN_ERR "%s: Error attempting to crypt page with "
 461                       "page_index = [%ld], extent_offset = [%ld]; "
 462                       "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 463                goto out;
 464        }
 465        rc = 0;
 466out:
 467        return rc;
 468}
 469
 470/**
 471 * ecryptfs_encrypt_page
 472 * @page: Page mapped from the eCryptfs inode for the file; contains
 473 *        decrypted content that needs to be encrypted (to a temporary
 474 *        page; not in place) and written out to the lower file
 475 *
 476 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 477 * that eCryptfs pages may straddle the lower pages -- for instance,
 478 * if the file was created on a machine with an 8K page size
 479 * (resulting in an 8K header), and then the file is copied onto a
 480 * host with a 32K page size, then when reading page 0 of the eCryptfs
 481 * file, 24K of page 0 of the lower file will be read and decrypted,
 482 * and then 8K of page 1 of the lower file will be read and decrypted.
 483 *
 484 * Returns zero on success; negative on error
 485 */
 486int ecryptfs_encrypt_page(struct page *page)
 487{
 488        struct inode *ecryptfs_inode;
 489        struct ecryptfs_crypt_stat *crypt_stat;
 490        char *enc_extent_virt;
 491        struct page *enc_extent_page = NULL;
 492        loff_t extent_offset;
 493        loff_t lower_offset;
 494        int rc = 0;
 495
 496        ecryptfs_inode = page->mapping->host;
 497        crypt_stat =
 498                &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 499        BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 500        enc_extent_page = alloc_page(GFP_USER);
 501        if (!enc_extent_page) {
 502                rc = -ENOMEM;
 503                ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 504                                "encrypted extent\n");
 505                goto out;
 506        }
 507
 508        for (extent_offset = 0;
 509             extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 510             extent_offset++) {
 511                rc = crypt_extent(crypt_stat, enc_extent_page, page,
 512                                  extent_offset, ENCRYPT);
 513                if (rc) {
 514                        printk(KERN_ERR "%s: Error encrypting extent; "
 515                               "rc = [%d]\n", __func__, rc);
 516                        goto out;
 517                }
 518        }
 519
 520        lower_offset = lower_offset_for_page(crypt_stat, page);
 521        enc_extent_virt = kmap(enc_extent_page);
 522        rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 523                                  PAGE_CACHE_SIZE);
 524        kunmap(enc_extent_page);
 525        if (rc < 0) {
 526                ecryptfs_printk(KERN_ERR,
 527                        "Error attempting to write lower page; rc = [%d]\n",
 528                        rc);
 529                goto out;
 530        }
 531        rc = 0;
 532out:
 533        if (enc_extent_page) {
 534                __free_page(enc_extent_page);
 535        }
 536        return rc;
 537}
 538
 539/**
 540 * ecryptfs_decrypt_page
 541 * @page: Page mapped from the eCryptfs inode for the file; data read
 542 *        and decrypted from the lower file will be written into this
 543 *        page
 544 *
 545 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 546 * that eCryptfs pages may straddle the lower pages -- for instance,
 547 * if the file was created on a machine with an 8K page size
 548 * (resulting in an 8K header), and then the file is copied onto a
 549 * host with a 32K page size, then when reading page 0 of the eCryptfs
 550 * file, 24K of page 0 of the lower file will be read and decrypted,
 551 * and then 8K of page 1 of the lower file will be read and decrypted.
 552 *
 553 * Returns zero on success; negative on error
 554 */
 555int ecryptfs_decrypt_page(struct page *page)
 556{
 557        struct inode *ecryptfs_inode;
 558        struct ecryptfs_crypt_stat *crypt_stat;
 559        char *page_virt;
 560        unsigned long extent_offset;
 561        loff_t lower_offset;
 562        int rc = 0;
 563
 564        ecryptfs_inode = page->mapping->host;
 565        crypt_stat =
 566                &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 567        BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 568
 569        lower_offset = lower_offset_for_page(crypt_stat, page);
 570        page_virt = kmap(page);
 571        rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_CACHE_SIZE,
 572                                 ecryptfs_inode);
 573        kunmap(page);
 574        if (rc < 0) {
 575                ecryptfs_printk(KERN_ERR,
 576                        "Error attempting to read lower page; rc = [%d]\n",
 577                        rc);
 578                goto out;
 579        }
 580
 581        for (extent_offset = 0;
 582             extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 583             extent_offset++) {
 584                rc = crypt_extent(crypt_stat, page, page,
 585                                  extent_offset, DECRYPT);
 586                if (rc) {
 587                        printk(KERN_ERR "%s: Error encrypting extent; "
 588                               "rc = [%d]\n", __func__, rc);
 589                        goto out;
 590                }
 591        }
 592out:
 593        return rc;
 594}
 595
 596#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 597
 598/**
 599 * ecryptfs_init_crypt_ctx
 600 * @crypt_stat: Uninitialized crypt stats structure
 601 *
 602 * Initialize the crypto context.
 603 *
 604 * TODO: Performance: Keep a cache of initialized cipher contexts;
 605 * only init if needed
 606 */
 607int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 608{
 609        char *full_alg_name;
 610        int rc = -EINVAL;
 611
 612        if (!crypt_stat->cipher) {
 613                ecryptfs_printk(KERN_ERR, "No cipher specified\n");
 614                goto out;
 615        }
 616        ecryptfs_printk(KERN_DEBUG,
 617                        "Initializing cipher [%s]; strlen = [%d]; "
 618                        "key_size_bits = [%zd]\n",
 619                        crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 620                        crypt_stat->key_size << 3);
 621        if (crypt_stat->tfm) {
 622                rc = 0;
 623                goto out;
 624        }
 625        mutex_lock(&crypt_stat->cs_tfm_mutex);
 626        rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 627                                                    crypt_stat->cipher, "cbc");
 628        if (rc)
 629                goto out_unlock;
 630        crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
 631        kfree(full_alg_name);
 632        if (IS_ERR(crypt_stat->tfm)) {
 633                rc = PTR_ERR(crypt_stat->tfm);
 634                crypt_stat->tfm = NULL;
 635                ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 636                                "Error initializing cipher [%s]\n",
 637                                crypt_stat->cipher);
 638                goto out_unlock;
 639        }
 640        crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 641        rc = 0;
 642out_unlock:
 643        mutex_unlock(&crypt_stat->cs_tfm_mutex);
 644out:
 645        return rc;
 646}
 647
 648static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 649{
 650        int extent_size_tmp;
 651
 652        crypt_stat->extent_mask = 0xFFFFFFFF;
 653        crypt_stat->extent_shift = 0;
 654        if (crypt_stat->extent_size == 0)
 655                return;
 656        extent_size_tmp = crypt_stat->extent_size;
 657        while ((extent_size_tmp & 0x01) == 0) {
 658                extent_size_tmp >>= 1;
 659                crypt_stat->extent_mask <<= 1;
 660                crypt_stat->extent_shift++;
 661        }
 662}
 663
 664void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 665{
 666        /* Default values; may be overwritten as we are parsing the
 667         * packets. */
 668        crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 669        set_extent_mask_and_shift(crypt_stat);
 670        crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 671        if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 672                crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 673        else {
 674                if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 675                        crypt_stat->metadata_size =
 676                                ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 677                else
 678                        crypt_stat->metadata_size = PAGE_CACHE_SIZE;
 679        }
 680}
 681
 682/**
 683 * ecryptfs_compute_root_iv
 684 * @crypt_stats
 685 *
 686 * On error, sets the root IV to all 0's.
 687 */
 688int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 689{
 690        int rc = 0;
 691        char dst[MD5_DIGEST_SIZE];
 692
 693        BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 694        BUG_ON(crypt_stat->iv_bytes <= 0);
 695        if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 696                rc = -EINVAL;
 697                ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 698                                "cannot generate root IV\n");
 699                goto out;
 700        }
 701        rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 702                                    crypt_stat->key_size);
 703        if (rc) {
 704                ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 705                                "MD5 while generating root IV\n");
 706                goto out;
 707        }
 708        memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 709out:
 710        if (rc) {
 711                memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 712                crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 713        }
 714        return rc;
 715}
 716
 717static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 718{
 719        get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 720        crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 721        ecryptfs_compute_root_iv(crypt_stat);
 722        if (unlikely(ecryptfs_verbosity > 0)) {
 723                ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 724                ecryptfs_dump_hex(crypt_stat->key,
 725                                  crypt_stat->key_size);
 726        }
 727}
 728
 729/**
 730 * ecryptfs_copy_mount_wide_flags_to_inode_flags
 731 * @crypt_stat: The inode's cryptographic context
 732 * @mount_crypt_stat: The mount point's cryptographic context
 733 *
 734 * This function propagates the mount-wide flags to individual inode
 735 * flags.
 736 */
 737static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 738        struct ecryptfs_crypt_stat *crypt_stat,
 739        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 740{
 741        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 742                crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 743        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 744                crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 745        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 746                crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 747                if (mount_crypt_stat->flags
 748                    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 749                        crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 750                else if (mount_crypt_stat->flags
 751                         & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 752                        crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 753        }
 754}
 755
 756static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 757        struct ecryptfs_crypt_stat *crypt_stat,
 758        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 759{
 760        struct ecryptfs_global_auth_tok *global_auth_tok;
 761        int rc = 0;
 762
 763        mutex_lock(&crypt_stat->keysig_list_mutex);
 764        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 765
 766        list_for_each_entry(global_auth_tok,
 767                            &mount_crypt_stat->global_auth_tok_list,
 768                            mount_crypt_stat_list) {
 769                if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 770                        continue;
 771                rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 772                if (rc) {
 773                        printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 774                        goto out;
 775                }
 776        }
 777
 778out:
 779        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 780        mutex_unlock(&crypt_stat->keysig_list_mutex);
 781        return rc;
 782}
 783
 784/**
 785 * ecryptfs_set_default_crypt_stat_vals
 786 * @crypt_stat: The inode's cryptographic context
 787 * @mount_crypt_stat: The mount point's cryptographic context
 788 *
 789 * Default values in the event that policy does not override them.
 790 */
 791static void ecryptfs_set_default_crypt_stat_vals(
 792        struct ecryptfs_crypt_stat *crypt_stat,
 793        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 794{
 795        ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 796                                                      mount_crypt_stat);
 797        ecryptfs_set_default_sizes(crypt_stat);
 798        strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 799        crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 800        crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 801        crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 802        crypt_stat->mount_crypt_stat = mount_crypt_stat;
 803}
 804
 805/**
 806 * ecryptfs_new_file_context
 807 * @ecryptfs_inode: The eCryptfs inode
 808 *
 809 * If the crypto context for the file has not yet been established,
 810 * this is where we do that.  Establishing a new crypto context
 811 * involves the following decisions:
 812 *  - What cipher to use?
 813 *  - What set of authentication tokens to use?
 814 * Here we just worry about getting enough information into the
 815 * authentication tokens so that we know that they are available.
 816 * We associate the available authentication tokens with the new file
 817 * via the set of signatures in the crypt_stat struct.  Later, when
 818 * the headers are actually written out, we may again defer to
 819 * userspace to perform the encryption of the session key; for the
 820 * foreseeable future, this will be the case with public key packets.
 821 *
 822 * Returns zero on success; non-zero otherwise
 823 */
 824int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 825{
 826        struct ecryptfs_crypt_stat *crypt_stat =
 827            &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 828        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 829            &ecryptfs_superblock_to_private(
 830                    ecryptfs_inode->i_sb)->mount_crypt_stat;
 831        int cipher_name_len;
 832        int rc = 0;
 833
 834        ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 835        crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 836        ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 837                                                      mount_crypt_stat);
 838        rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 839                                                         mount_crypt_stat);
 840        if (rc) {
 841                printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 842                       "to the inode key sigs; rc = [%d]\n", rc);
 843                goto out;
 844        }
 845        cipher_name_len =
 846                strlen(mount_crypt_stat->global_default_cipher_name);
 847        memcpy(crypt_stat->cipher,
 848               mount_crypt_stat->global_default_cipher_name,
 849               cipher_name_len);
 850        crypt_stat->cipher[cipher_name_len] = '\0';
 851        crypt_stat->key_size =
 852                mount_crypt_stat->global_default_cipher_key_size;
 853        ecryptfs_generate_new_key(crypt_stat);
 854        rc = ecryptfs_init_crypt_ctx(crypt_stat);
 855        if (rc)
 856                ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 857                                "context for cipher [%s]: rc = [%d]\n",
 858                                crypt_stat->cipher, rc);
 859out:
 860        return rc;
 861}
 862
 863/**
 864 * ecryptfs_validate_marker - check for the ecryptfs marker
 865 * @data: The data block in which to check
 866 *
 867 * Returns zero if marker found; -EINVAL if not found
 868 */
 869static int ecryptfs_validate_marker(char *data)
 870{
 871        u32 m_1, m_2;
 872
 873        m_1 = get_unaligned_be32(data);
 874        m_2 = get_unaligned_be32(data + 4);
 875        if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 876                return 0;
 877        ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
 878                        "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
 879                        MAGIC_ECRYPTFS_MARKER);
 880        ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
 881                        "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
 882        return -EINVAL;
 883}
 884
 885struct ecryptfs_flag_map_elem {
 886        u32 file_flag;
 887        u32 local_flag;
 888};
 889
 890/* Add support for additional flags by adding elements here. */
 891static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 892        {0x00000001, ECRYPTFS_ENABLE_HMAC},
 893        {0x00000002, ECRYPTFS_ENCRYPTED},
 894        {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
 895        {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 896};
 897
 898/**
 899 * ecryptfs_process_flags
 900 * @crypt_stat: The cryptographic context
 901 * @page_virt: Source data to be parsed
 902 * @bytes_read: Updated with the number of bytes read
 903 *
 904 * Returns zero on success; non-zero if the flag set is invalid
 905 */
 906static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
 907                                  char *page_virt, int *bytes_read)
 908{
 909        int rc = 0;
 910        int i;
 911        u32 flags;
 912
 913        flags = get_unaligned_be32(page_virt);
 914        for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 915                          / sizeof(struct ecryptfs_flag_map_elem))); i++)
 916                if (flags & ecryptfs_flag_map[i].file_flag) {
 917                        crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
 918                } else
 919                        crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
 920        /* Version is in top 8 bits of the 32-bit flag vector */
 921        crypt_stat->file_version = ((flags >> 24) & 0xFF);
 922        (*bytes_read) = 4;
 923        return rc;
 924}
 925
 926/**
 927 * write_ecryptfs_marker
 928 * @page_virt: The pointer to in a page to begin writing the marker
 929 * @written: Number of bytes written
 930 *
 931 * Marker = 0x3c81b7f5
 932 */
 933static void write_ecryptfs_marker(char *page_virt, size_t *written)
 934{
 935        u32 m_1, m_2;
 936
 937        get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 938        m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 939        put_unaligned_be32(m_1, page_virt);
 940        page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 941        put_unaligned_be32(m_2, page_virt);
 942        (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 943}
 944
 945void ecryptfs_write_crypt_stat_flags(char *page_virt,
 946                                     struct ecryptfs_crypt_stat *crypt_stat,
 947                                     size_t *written)
 948{
 949        u32 flags = 0;
 950        int i;
 951
 952        for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 953                          / sizeof(struct ecryptfs_flag_map_elem))); i++)
 954                if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
 955                        flags |= ecryptfs_flag_map[i].file_flag;
 956        /* Version is in top 8 bits of the 32-bit flag vector */
 957        flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
 958        put_unaligned_be32(flags, page_virt);
 959        (*written) = 4;
 960}
 961
 962struct ecryptfs_cipher_code_str_map_elem {
 963        char cipher_str[16];
 964        u8 cipher_code;
 965};
 966
 967/* Add support for additional ciphers by adding elements here. The
 968 * cipher_code is whatever OpenPGP applicatoins use to identify the
 969 * ciphers. List in order of probability. */
 970static struct ecryptfs_cipher_code_str_map_elem
 971ecryptfs_cipher_code_str_map[] = {
 972        {"aes",RFC2440_CIPHER_AES_128 },
 973        {"blowfish", RFC2440_CIPHER_BLOWFISH},
 974        {"des3_ede", RFC2440_CIPHER_DES3_EDE},
 975        {"cast5", RFC2440_CIPHER_CAST_5},
 976        {"twofish", RFC2440_CIPHER_TWOFISH},
 977        {"cast6", RFC2440_CIPHER_CAST_6},
 978        {"aes", RFC2440_CIPHER_AES_192},
 979        {"aes", RFC2440_CIPHER_AES_256}
 980};
 981
 982/**
 983 * ecryptfs_code_for_cipher_string
 984 * @cipher_name: The string alias for the cipher
 985 * @key_bytes: Length of key in bytes; used for AES code selection
 986 *
 987 * Returns zero on no match, or the cipher code on match
 988 */
 989u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 990{
 991        int i;
 992        u8 code = 0;
 993        struct ecryptfs_cipher_code_str_map_elem *map =
 994                ecryptfs_cipher_code_str_map;
 995
 996        if (strcmp(cipher_name, "aes") == 0) {
 997                switch (key_bytes) {
 998                case 16:
 999                        code = RFC2440_CIPHER_AES_128;
1000                        break;
1001                case 24:
1002                        code = RFC2440_CIPHER_AES_192;
1003                        break;
1004                case 32:
1005                        code = RFC2440_CIPHER_AES_256;
1006                }
1007        } else {
1008                for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1009                        if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1010                                code = map[i].cipher_code;
1011                                break;
1012                        }
1013        }
1014        return code;
1015}
1016
1017/**
1018 * ecryptfs_cipher_code_to_string
1019 * @str: Destination to write out the cipher name
1020 * @cipher_code: The code to convert to cipher name string
1021 *
1022 * Returns zero on success
1023 */
1024int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1025{
1026        int rc = 0;
1027        int i;
1028
1029        str[0] = '\0';
1030        for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1031                if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1032                        strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1033        if (str[0] == '\0') {
1034                ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1035                                "[%d]\n", cipher_code);
1036                rc = -EINVAL;
1037        }
1038        return rc;
1039}
1040
1041int ecryptfs_read_and_validate_header_region(struct inode *inode)
1042{
1043        u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1044        u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1045        int rc;
1046
1047        rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1048                                 inode);
1049        if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1050                return rc >= 0 ? -EINVAL : rc;
1051        rc = ecryptfs_validate_marker(marker);
1052        if (!rc)
1053                ecryptfs_i_size_init(file_size, inode);
1054        return rc;
1055}
1056
1057void
1058ecryptfs_write_header_metadata(char *virt,
1059                               struct ecryptfs_crypt_stat *crypt_stat,
1060                               size_t *written)
1061{
1062        u32 header_extent_size;
1063        u16 num_header_extents_at_front;
1064
1065        header_extent_size = (u32)crypt_stat->extent_size;
1066        num_header_extents_at_front =
1067                (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1068        put_unaligned_be32(header_extent_size, virt);
1069        virt += 4;
1070        put_unaligned_be16(num_header_extents_at_front, virt);
1071        (*written) = 6;
1072}
1073
1074struct kmem_cache *ecryptfs_header_cache;
1075
1076/**
1077 * ecryptfs_write_headers_virt
1078 * @page_virt: The virtual address to write the headers to
1079 * @max: The size of memory allocated at page_virt
1080 * @size: Set to the number of bytes written by this function
1081 * @crypt_stat: The cryptographic context
1082 * @ecryptfs_dentry: The eCryptfs dentry
1083 *
1084 * Format version: 1
1085 *
1086 *   Header Extent:
1087 *     Octets 0-7:        Unencrypted file size (big-endian)
1088 *     Octets 8-15:       eCryptfs special marker
1089 *     Octets 16-19:      Flags
1090 *      Octet 16:         File format version number (between 0 and 255)
1091 *      Octets 17-18:     Reserved
1092 *      Octet 19:         Bit 1 (lsb): Reserved
1093 *                        Bit 2: Encrypted?
1094 *                        Bits 3-8: Reserved
1095 *     Octets 20-23:      Header extent size (big-endian)
1096 *     Octets 24-25:      Number of header extents at front of file
1097 *                        (big-endian)
1098 *     Octet  26:         Begin RFC 2440 authentication token packet set
1099 *   Data Extent 0:
1100 *     Lower data (CBC encrypted)
1101 *   Data Extent 1:
1102 *     Lower data (CBC encrypted)
1103 *   ...
1104 *
1105 * Returns zero on success
1106 */
1107static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1108                                       size_t *size,
1109                                       struct ecryptfs_crypt_stat *crypt_stat,
1110                                       struct dentry *ecryptfs_dentry)
1111{
1112        int rc;
1113        size_t written;
1114        size_t offset;
1115
1116        offset = ECRYPTFS_FILE_SIZE_BYTES;
1117        write_ecryptfs_marker((page_virt + offset), &written);
1118        offset += written;
1119        ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1120                                        &written);
1121        offset += written;
1122        ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1123                                       &written);
1124        offset += written;
1125        rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1126                                              ecryptfs_dentry, &written,
1127                                              max - offset);
1128        if (rc)
1129                ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1130                                "set; rc = [%d]\n", rc);
1131        if (size) {
1132                offset += written;
1133                *size = offset;
1134        }
1135        return rc;
1136}
1137
1138static int
1139ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1140                                    char *virt, size_t virt_len)
1141{
1142        int rc;
1143
1144        rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1145                                  0, virt_len);
1146        if (rc < 0)
1147                printk(KERN_ERR "%s: Error attempting to write header "
1148                       "information to lower file; rc = [%d]\n", __func__, rc);
1149        else
1150                rc = 0;
1151        return rc;
1152}
1153
1154static int
1155ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1156                                 char *page_virt, size_t size)
1157{
1158        int rc;
1159
1160        rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1161                               size, 0);
1162        return rc;
1163}
1164
1165static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1166                                               unsigned int order)
1167{
1168        struct page *page;
1169
1170        page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1171        if (page)
1172                return (unsigned long) page_address(page);
1173        return 0;
1174}
1175
1176/**
1177 * ecryptfs_write_metadata
1178 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1179 * @ecryptfs_inode: The newly created eCryptfs inode
1180 *
1181 * Write the file headers out.  This will likely involve a userspace
1182 * callout, in which the session key is encrypted with one or more
1183 * public keys and/or the passphrase necessary to do the encryption is
1184 * retrieved via a prompt.  Exactly what happens at this point should
1185 * be policy-dependent.
1186 *
1187 * Returns zero on success; non-zero on error
1188 */
1189int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1190                            struct inode *ecryptfs_inode)
1191{
1192        struct ecryptfs_crypt_stat *crypt_stat =
1193                &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1194        unsigned int order;
1195        char *virt;
1196        size_t virt_len;
1197        size_t size = 0;
1198        int rc = 0;
1199
1200        if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1201                if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1202                        printk(KERN_ERR "Key is invalid; bailing out\n");
1203                        rc = -EINVAL;
1204                        goto out;
1205                }
1206        } else {
1207                printk(KERN_WARNING "%s: Encrypted flag not set\n",
1208                       __func__);
1209                rc = -EINVAL;
1210                goto out;
1211        }
1212        virt_len = crypt_stat->metadata_size;
1213        order = get_order(virt_len);
1214        /* Released in this function */
1215        virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1216        if (!virt) {
1217                printk(KERN_ERR "%s: Out of memory\n", __func__);
1218                rc = -ENOMEM;
1219                goto out;
1220        }
1221        /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1222        rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1223                                         ecryptfs_dentry);
1224        if (unlikely(rc)) {
1225                printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1226                       __func__, rc);
1227                goto out_free;
1228        }
1229        if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1230                rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1231                                                      size);
1232        else
1233                rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1234                                                         virt_len);
1235        if (rc) {
1236                printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1237                       "rc = [%d]\n", __func__, rc);
1238                goto out_free;
1239        }
1240out_free:
1241        free_pages((unsigned long)virt, order);
1242out:
1243        return rc;
1244}
1245
1246#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1247#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1248static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1249                                 char *virt, int *bytes_read,
1250                                 int validate_header_size)
1251{
1252        int rc = 0;
1253        u32 header_extent_size;
1254        u16 num_header_extents_at_front;
1255
1256        header_extent_size = get_unaligned_be32(virt);
1257        virt += sizeof(__be32);
1258        num_header_extents_at_front = get_unaligned_be16(virt);
1259        crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1260                                     * (size_t)header_extent_size));
1261        (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1262        if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1263            && (crypt_stat->metadata_size
1264                < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1265                rc = -EINVAL;
1266                printk(KERN_WARNING "Invalid header size: [%zd]\n",
1267                       crypt_stat->metadata_size);
1268        }
1269        return rc;
1270}
1271
1272/**
1273 * set_default_header_data
1274 * @crypt_stat: The cryptographic context
1275 *
1276 * For version 0 file format; this function is only for backwards
1277 * compatibility for files created with the prior versions of
1278 * eCryptfs.
1279 */
1280static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1281{
1282        crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1283}
1284
1285void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1286{
1287        struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1288        struct ecryptfs_crypt_stat *crypt_stat;
1289        u64 file_size;
1290
1291        crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1292        mount_crypt_stat =
1293                &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1294        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1295                file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1296                if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1297                        file_size += crypt_stat->metadata_size;
1298        } else
1299                file_size = get_unaligned_be64(page_virt);
1300        i_size_write(inode, (loff_t)file_size);
1301        crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1302}
1303
1304/**
1305 * ecryptfs_read_headers_virt
1306 * @page_virt: The virtual address into which to read the headers
1307 * @crypt_stat: The cryptographic context
1308 * @ecryptfs_dentry: The eCryptfs dentry
1309 * @validate_header_size: Whether to validate the header size while reading
1310 *
1311 * Read/parse the header data. The header format is detailed in the
1312 * comment block for the ecryptfs_write_headers_virt() function.
1313 *
1314 * Returns zero on success
1315 */
1316static int ecryptfs_read_headers_virt(char *page_virt,
1317                                      struct ecryptfs_crypt_stat *crypt_stat,
1318                                      struct dentry *ecryptfs_dentry,
1319                                      int validate_header_size)
1320{
1321        int rc = 0;
1322        int offset;
1323        int bytes_read;
1324
1325        ecryptfs_set_default_sizes(crypt_stat);
1326        crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1327                ecryptfs_dentry->d_sb)->mount_crypt_stat;
1328        offset = ECRYPTFS_FILE_SIZE_BYTES;
1329        rc = ecryptfs_validate_marker(page_virt + offset);
1330        if (rc)
1331                goto out;
1332        if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1333                ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1334        offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1335        rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1336                                    &bytes_read);
1337        if (rc) {
1338                ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1339                goto out;
1340        }
1341        if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1342                ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1343                                "file version [%d] is supported by this "
1344                                "version of eCryptfs\n",
1345                                crypt_stat->file_version,
1346                                ECRYPTFS_SUPPORTED_FILE_VERSION);
1347                rc = -EINVAL;
1348                goto out;
1349        }
1350        offset += bytes_read;
1351        if (crypt_stat->file_version >= 1) {
1352                rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1353                                           &bytes_read, validate_header_size);
1354                if (rc) {
1355                        ecryptfs_printk(KERN_WARNING, "Error reading header "
1356                                        "metadata; rc = [%d]\n", rc);
1357                }
1358                offset += bytes_read;
1359        } else
1360                set_default_header_data(crypt_stat);
1361        rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1362                                       ecryptfs_dentry);
1363out:
1364        return rc;
1365}
1366
1367/**
1368 * ecryptfs_read_xattr_region
1369 * @page_virt: The vitual address into which to read the xattr data
1370 * @ecryptfs_inode: The eCryptfs inode
1371 *
1372 * Attempts to read the crypto metadata from the extended attribute
1373 * region of the lower file.
1374 *
1375 * Returns zero on success; non-zero on error
1376 */
1377int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1378{
1379        struct dentry *lower_dentry =
1380                ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1381        ssize_t size;
1382        int rc = 0;
1383
1384        size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1385                                       page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1386        if (size < 0) {
1387                if (unlikely(ecryptfs_verbosity > 0))
1388                        printk(KERN_INFO "Error attempting to read the [%s] "
1389                               "xattr from the lower file; return value = "
1390                               "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1391                rc = -EINVAL;
1392                goto out;
1393        }
1394out:
1395        return rc;
1396}
1397
1398int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1399                                            struct inode *inode)
1400{
1401        u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1402        u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1403        int rc;
1404
1405        rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1406                                     ECRYPTFS_XATTR_NAME, file_size,
1407                                     ECRYPTFS_SIZE_AND_MARKER_BYTES);
1408        if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1409                return rc >= 0 ? -EINVAL : rc;
1410        rc = ecryptfs_validate_marker(marker);
1411        if (!rc)
1412                ecryptfs_i_size_init(file_size, inode);
1413        return rc;
1414}
1415
1416/**
1417 * ecryptfs_read_metadata
1418 *
1419 * Common entry point for reading file metadata. From here, we could
1420 * retrieve the header information from the header region of the file,
1421 * the xattr region of the file, or some other repostory that is
1422 * stored separately from the file itself. The current implementation
1423 * supports retrieving the metadata information from the file contents
1424 * and from the xattr region.
1425 *
1426 * Returns zero if valid headers found and parsed; non-zero otherwise
1427 */
1428int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1429{
1430        int rc;
1431        char *page_virt;
1432        struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1433        struct ecryptfs_crypt_stat *crypt_stat =
1434            &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1435        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1436                &ecryptfs_superblock_to_private(
1437                        ecryptfs_dentry->d_sb)->mount_crypt_stat;
1438
1439        ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1440                                                      mount_crypt_stat);
1441        /* Read the first page from the underlying file */
1442        page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1443        if (!page_virt) {
1444                rc = -ENOMEM;
1445                printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1446                       __func__);
1447                goto out;
1448        }
1449        rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1450                                 ecryptfs_inode);
1451        if (rc >= 0)
1452                rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1453                                                ecryptfs_dentry,
1454                                                ECRYPTFS_VALIDATE_HEADER_SIZE);
1455        if (rc) {
1456                /* metadata is not in the file header, so try xattrs */
1457                memset(page_virt, 0, PAGE_CACHE_SIZE);
1458                rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1459                if (rc) {
1460                        printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1461                               "file header region or xattr region, inode %lu\n",
1462                                ecryptfs_inode->i_ino);
1463                        rc = -EINVAL;
1464                        goto out;
1465                }
1466                rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1467                                                ecryptfs_dentry,
1468                                                ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1469                if (rc) {
1470                        printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1471                               "file xattr region either, inode %lu\n",
1472                                ecryptfs_inode->i_ino);
1473                        rc = -EINVAL;
1474                }
1475                if (crypt_stat->mount_crypt_stat->flags
1476                    & ECRYPTFS_XATTR_METADATA_ENABLED) {
1477                        crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1478                } else {
1479                        printk(KERN_WARNING "Attempt to access file with "
1480                               "crypto metadata only in the extended attribute "
1481                               "region, but eCryptfs was mounted without "
1482                               "xattr support enabled. eCryptfs will not treat "
1483                               "this like an encrypted file, inode %lu\n",
1484                                ecryptfs_inode->i_ino);
1485                        rc = -EINVAL;
1486                }
1487        }
1488out:
1489        if (page_virt) {
1490                memset(page_virt, 0, PAGE_CACHE_SIZE);
1491                kmem_cache_free(ecryptfs_header_cache, page_virt);
1492        }
1493        return rc;
1494}
1495
1496/**
1497 * ecryptfs_encrypt_filename - encrypt filename
1498 *
1499 * CBC-encrypts the filename. We do not want to encrypt the same
1500 * filename with the same key and IV, which may happen with hard
1501 * links, so we prepend random bits to each filename.
1502 *
1503 * Returns zero on success; non-zero otherwise
1504 */
1505static int
1506ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1507                          struct ecryptfs_crypt_stat *crypt_stat,
1508                          struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1509{
1510        int rc = 0;
1511
1512        filename->encrypted_filename = NULL;
1513        filename->encrypted_filename_size = 0;
1514        if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1515            || (mount_crypt_stat && (mount_crypt_stat->flags
1516                                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1517                size_t packet_size;
1518                size_t remaining_bytes;
1519
1520                rc = ecryptfs_write_tag_70_packet(
1521                        NULL, NULL,
1522                        &filename->encrypted_filename_size,
1523                        mount_crypt_stat, NULL,
1524                        filename->filename_size);
1525                if (rc) {
1526                        printk(KERN_ERR "%s: Error attempting to get packet "
1527                               "size for tag 72; rc = [%d]\n", __func__,
1528                               rc);
1529                        filename->encrypted_filename_size = 0;
1530                        goto out;
1531                }
1532                filename->encrypted_filename =
1533                        kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1534                if (!filename->encrypted_filename) {
1535                        printk(KERN_ERR "%s: Out of memory whilst attempting "
1536                               "to kmalloc [%zd] bytes\n", __func__,
1537                               filename->encrypted_filename_size);
1538                        rc = -ENOMEM;
1539                        goto out;
1540                }
1541                remaining_bytes = filename->encrypted_filename_size;
1542                rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1543                                                  &remaining_bytes,
1544                                                  &packet_size,
1545                                                  mount_crypt_stat,
1546                                                  filename->filename,
1547                                                  filename->filename_size);
1548                if (rc) {
1549                        printk(KERN_ERR "%s: Error attempting to generate "
1550                               "tag 70 packet; rc = [%d]\n", __func__,
1551                               rc);
1552                        kfree(filename->encrypted_filename);
1553                        filename->encrypted_filename = NULL;
1554                        filename->encrypted_filename_size = 0;
1555                        goto out;
1556                }
1557                filename->encrypted_filename_size = packet_size;
1558        } else {
1559                printk(KERN_ERR "%s: No support for requested filename "
1560                       "encryption method in this release\n", __func__);
1561                rc = -EOPNOTSUPP;
1562                goto out;
1563        }
1564out:
1565        return rc;
1566}
1567
1568static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1569                                  const char *name, size_t name_size)
1570{
1571        int rc = 0;
1572
1573        (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1574        if (!(*copied_name)) {
1575                rc = -ENOMEM;
1576                goto out;
1577        }
1578        memcpy((void *)(*copied_name), (void *)name, name_size);
1579        (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1580                                                 * in printing out the
1581                                                 * string in debug
1582                                                 * messages */
1583        (*copied_name_size) = name_size;
1584out:
1585        return rc;
1586}
1587
1588/**
1589 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1590 * @key_tfm: Crypto context for key material, set by this function
1591 * @cipher_name: Name of the cipher
1592 * @key_size: Size of the key in bytes
1593 *
1594 * Returns zero on success. Any crypto_tfm structs allocated here
1595 * should be released by other functions, such as on a superblock put
1596 * event, regardless of whether this function succeeds for fails.
1597 */
1598static int
1599ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1600                            char *cipher_name, size_t *key_size)
1601{
1602        char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1603        char *full_alg_name = NULL;
1604        int rc;
1605
1606        *key_tfm = NULL;
1607        if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1608                rc = -EINVAL;
1609                printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1610                      "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1611                goto out;
1612        }
1613        rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1614                                                    "ecb");
1615        if (rc)
1616                goto out;
1617        *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1618        if (IS_ERR(*key_tfm)) {
1619                rc = PTR_ERR(*key_tfm);
1620                printk(KERN_ERR "Unable to allocate crypto cipher with name "
1621                       "[%s]; rc = [%d]\n", full_alg_name, rc);
1622                goto out;
1623        }
1624        crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1625        if (*key_size == 0) {
1626                struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1627
1628                *key_size = alg->max_keysize;
1629        }
1630        get_random_bytes(dummy_key, *key_size);
1631        rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1632        if (rc) {
1633                printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1634                       "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1635                       rc);
1636                rc = -EINVAL;
1637                goto out;
1638        }
1639out:
1640        kfree(full_alg_name);
1641        return rc;
1642}
1643
1644struct kmem_cache *ecryptfs_key_tfm_cache;
1645static struct list_head key_tfm_list;
1646struct mutex key_tfm_list_mutex;
1647
1648int __init ecryptfs_init_crypto(void)
1649{
1650        mutex_init(&key_tfm_list_mutex);
1651        INIT_LIST_HEAD(&key_tfm_list);
1652        return 0;
1653}
1654
1655/**
1656 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1657 *
1658 * Called only at module unload time
1659 */
1660int ecryptfs_destroy_crypto(void)
1661{
1662        struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1663
1664        mutex_lock(&key_tfm_list_mutex);
1665        list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1666                                 key_tfm_list) {
1667                list_del(&key_tfm->key_tfm_list);
1668                if (key_tfm->key_tfm)
1669                        crypto_free_blkcipher(key_tfm->key_tfm);
1670                kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1671        }
1672        mutex_unlock(&key_tfm_list_mutex);
1673        return 0;
1674}
1675
1676int
1677ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1678                         size_t key_size)
1679{
1680        struct ecryptfs_key_tfm *tmp_tfm;
1681        int rc = 0;
1682
1683        BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1684
1685        tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1686        if (key_tfm != NULL)
1687                (*key_tfm) = tmp_tfm;
1688        if (!tmp_tfm) {
1689                rc = -ENOMEM;
1690                printk(KERN_ERR "Error attempting to allocate from "
1691                       "ecryptfs_key_tfm_cache\n");
1692                goto out;
1693        }
1694        mutex_init(&tmp_tfm->key_tfm_mutex);
1695        strncpy(tmp_tfm->cipher_name, cipher_name,
1696                ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1697        tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1698        tmp_tfm->key_size = key_size;
1699        rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1700                                         tmp_tfm->cipher_name,
1701                                         &tmp_tfm->key_size);
1702        if (rc) {
1703                printk(KERN_ERR "Error attempting to initialize key TFM "
1704                       "cipher with name = [%s]; rc = [%d]\n",
1705                       tmp_tfm->cipher_name, rc);
1706                kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1707                if (key_tfm != NULL)
1708                        (*key_tfm) = NULL;
1709                goto out;
1710        }
1711        list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1712out:
1713        return rc;
1714}
1715
1716/**
1717 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1718 * @cipher_name: the name of the cipher to search for
1719 * @key_tfm: set to corresponding tfm if found
1720 *
1721 * Searches for cached key_tfm matching @cipher_name
1722 * Must be called with &key_tfm_list_mutex held
1723 * Returns 1 if found, with @key_tfm set
1724 * Returns 0 if not found, with @key_tfm set to NULL
1725 */
1726int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1727{
1728        struct ecryptfs_key_tfm *tmp_key_tfm;
1729
1730        BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1731
1732        list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1733                if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1734                        if (key_tfm)
1735                                (*key_tfm) = tmp_key_tfm;
1736                        return 1;
1737                }
1738        }
1739        if (key_tfm)
1740                (*key_tfm) = NULL;
1741        return 0;
1742}
1743
1744/**
1745 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1746 *
1747 * @tfm: set to cached tfm found, or new tfm created
1748 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1749 * @cipher_name: the name of the cipher to search for and/or add
1750 *
1751 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1752 * Searches for cached item first, and creates new if not found.
1753 * Returns 0 on success, non-zero if adding new cipher failed
1754 */
1755int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1756                                               struct mutex **tfm_mutex,
1757                                               char *cipher_name)
1758{
1759        struct ecryptfs_key_tfm *key_tfm;
1760        int rc = 0;
1761
1762        (*tfm) = NULL;
1763        (*tfm_mutex) = NULL;
1764
1765        mutex_lock(&key_tfm_list_mutex);
1766        if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1767                rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1768                if (rc) {
1769                        printk(KERN_ERR "Error adding new key_tfm to list; "
1770                                        "rc = [%d]\n", rc);
1771                        goto out;
1772                }
1773        }
1774        (*tfm) = key_tfm->key_tfm;
1775        (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1776out:
1777        mutex_unlock(&key_tfm_list_mutex);
1778        return rc;
1779}
1780
1781/* 64 characters forming a 6-bit target field */
1782static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1783                                                 "EFGHIJKLMNOPQRST"
1784                                                 "UVWXYZabcdefghij"
1785                                                 "klmnopqrstuvwxyz");
1786
1787/* We could either offset on every reverse map or just pad some 0x00's
1788 * at the front here */
1789static const unsigned char filename_rev_map[256] = {
1790        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1791        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1792        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1793        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1794        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1795        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1796        0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1797        0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1798        0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1799        0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1800        0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1801        0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1802        0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1803        0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1804        0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1805        0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1806};
1807
1808/**
1809 * ecryptfs_encode_for_filename
1810 * @dst: Destination location for encoded filename
1811 * @dst_size: Size of the encoded filename in bytes
1812 * @src: Source location for the filename to encode
1813 * @src_size: Size of the source in bytes
1814 */
1815static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1816                                  unsigned char *src, size_t src_size)
1817{
1818        size_t num_blocks;
1819        size_t block_num = 0;
1820        size_t dst_offset = 0;
1821        unsigned char last_block[3];
1822
1823        if (src_size == 0) {
1824                (*dst_size) = 0;
1825                goto out;
1826        }
1827        num_blocks = (src_size / 3);
1828        if ((src_size % 3) == 0) {
1829                memcpy(last_block, (&src[src_size - 3]), 3);
1830        } else {
1831                num_blocks++;
1832                last_block[2] = 0x00;
1833                switch (src_size % 3) {
1834                case 1:
1835                        last_block[0] = src[src_size - 1];
1836                        last_block[1] = 0x00;
1837                        break;
1838                case 2:
1839                        last_block[0] = src[src_size - 2];
1840                        last_block[1] = src[src_size - 1];
1841                }
1842        }
1843        (*dst_size) = (num_blocks * 4);
1844        if (!dst)
1845                goto out;
1846        while (block_num < num_blocks) {
1847                unsigned char *src_block;
1848                unsigned char dst_block[4];
1849
1850                if (block_num == (num_blocks - 1))
1851                        src_block = last_block;
1852                else
1853                        src_block = &src[block_num * 3];
1854                dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1855                dst_block[1] = (((src_block[0] << 4) & 0x30)
1856                                | ((src_block[1] >> 4) & 0x0F));
1857                dst_block[2] = (((src_block[1] << 2) & 0x3C)
1858                                | ((src_block[2] >> 6) & 0x03));
1859                dst_block[3] = (src_block[2] & 0x3F);
1860                dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1861                dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1862                dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1863                dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1864                block_num++;
1865        }
1866out:
1867        return;
1868}
1869
1870static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1871{
1872        /* Not exact; conservatively long. Every block of 4
1873         * encoded characters decodes into a block of 3
1874         * decoded characters. This segment of code provides
1875         * the caller with the maximum amount of allocated
1876         * space that @dst will need to point to in a
1877         * subsequent call. */
1878        return ((encoded_size + 1) * 3) / 4;
1879}
1880
1881/**
1882 * ecryptfs_decode_from_filename
1883 * @dst: If NULL, this function only sets @dst_size and returns. If
1884 *       non-NULL, this function decodes the encoded octets in @src
1885 *       into the memory that @dst points to.
1886 * @dst_size: Set to the size of the decoded string.
1887 * @src: The encoded set of octets to decode.
1888 * @src_size: The size of the encoded set of octets to decode.
1889 */
1890static void
1891ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1892                              const unsigned char *src, size_t src_size)
1893{
1894        u8 current_bit_offset = 0;
1895        size_t src_byte_offset = 0;
1896        size_t dst_byte_offset = 0;
1897
1898        if (dst == NULL) {
1899                (*dst_size) = ecryptfs_max_decoded_size(src_size);
1900                goto out;
1901        }
1902        while (src_byte_offset < src_size) {
1903                unsigned char src_byte =
1904                                filename_rev_map[(int)src[src_byte_offset]];
1905
1906                switch (current_bit_offset) {
1907                case 0:
1908                        dst[dst_byte_offset] = (src_byte << 2);
1909                        current_bit_offset = 6;
1910                        break;
1911                case 6:
1912                        dst[dst_byte_offset++] |= (src_byte >> 4);
1913                        dst[dst_byte_offset] = ((src_byte & 0xF)
1914                                                 << 4);
1915                        current_bit_offset = 4;
1916                        break;
1917                case 4:
1918                        dst[dst_byte_offset++] |= (src_byte >> 2);
1919                        dst[dst_byte_offset] = (src_byte << 6);
1920                        current_bit_offset = 2;
1921                        break;
1922                case 2:
1923                        dst[dst_byte_offset++] |= (src_byte);
1924                        dst[dst_byte_offset] = 0;
1925                        current_bit_offset = 0;
1926                        break;
1927                }
1928                src_byte_offset++;
1929        }
1930        (*dst_size) = dst_byte_offset;
1931out:
1932        return;
1933}
1934
1935/**
1936 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1937 * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1938 * @name: The plaintext name
1939 * @length: The length of the plaintext
1940 * @encoded_name: The encypted name
1941 *
1942 * Encrypts and encodes a filename into something that constitutes a
1943 * valid filename for a filesystem, with printable characters.
1944 *
1945 * We assume that we have a properly initialized crypto context,
1946 * pointed to by crypt_stat->tfm.
1947 *
1948 * Returns zero on success; non-zero on otherwise
1949 */
1950int ecryptfs_encrypt_and_encode_filename(
1951        char **encoded_name,
1952        size_t *encoded_name_size,
1953        struct ecryptfs_crypt_stat *crypt_stat,
1954        struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1955        const char *name, size_t name_size)
1956{
1957        size_t encoded_name_no_prefix_size;
1958        int rc = 0;
1959
1960        (*encoded_name) = NULL;
1961        (*encoded_name_size) = 0;
1962        if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
1963            || (mount_crypt_stat && (mount_crypt_stat->flags
1964                                     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
1965                struct ecryptfs_filename *filename;
1966
1967                filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1968                if (!filename) {
1969                        printk(KERN_ERR "%s: Out of memory whilst attempting "
1970                               "to kzalloc [%zd] bytes\n", __func__,
1971                               sizeof(*filename));
1972                        rc = -ENOMEM;
1973                        goto out;
1974                }
1975                filename->filename = (char *)name;
1976                filename->filename_size = name_size;
1977                rc = ecryptfs_encrypt_filename(filename, crypt_stat,
1978                                               mount_crypt_stat);
1979                if (rc) {
1980                        printk(KERN_ERR "%s: Error attempting to encrypt "
1981                               "filename; rc = [%d]\n", __func__, rc);
1982                        kfree(filename);
1983                        goto out;
1984                }
1985                ecryptfs_encode_for_filename(
1986                        NULL, &encoded_name_no_prefix_size,
1987                        filename->encrypted_filename,
1988                        filename->encrypted_filename_size);
1989                if ((crypt_stat && (crypt_stat->flags
1990                                    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1991                    || (mount_crypt_stat
1992                        && (mount_crypt_stat->flags
1993                            & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
1994                        (*encoded_name_size) =
1995                                (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1996                                 + encoded_name_no_prefix_size);
1997                else
1998                        (*encoded_name_size) =
1999                                (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2000                                 + encoded_name_no_prefix_size);
2001                (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2002                if (!(*encoded_name)) {
2003                        printk(KERN_ERR "%s: Out of memory whilst attempting "
2004                               "to kzalloc [%zd] bytes\n", __func__,
2005                               (*encoded_name_size));
2006                        rc = -ENOMEM;
2007                        kfree(filename->encrypted_filename);
2008                        kfree(filename);
2009                        goto out;
2010                }
2011                if ((crypt_stat && (crypt_stat->flags
2012                                    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2013                    || (mount_crypt_stat
2014                        && (mount_crypt_stat->flags
2015                            & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2016                        memcpy((*encoded_name),
2017                               ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2018                               ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2019                        ecryptfs_encode_for_filename(
2020                            ((*encoded_name)
2021                             + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2022                            &encoded_name_no_prefix_size,
2023                            filename->encrypted_filename,
2024                            filename->encrypted_filename_size);
2025                        (*encoded_name_size) =
2026                                (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2027                                 + encoded_name_no_prefix_size);
2028                        (*encoded_name)[(*encoded_name_size)] = '\0';
2029                } else {
2030                        rc = -EOPNOTSUPP;
2031                }
2032                if (rc) {
2033                        printk(KERN_ERR "%s: Error attempting to encode "
2034                               "encrypted filename; rc = [%d]\n", __func__,
2035                               rc);
2036                        kfree((*encoded_name));
2037                        (*encoded_name) = NULL;
2038                        (*encoded_name_size) = 0;
2039                }
2040                kfree(filename->encrypted_filename);
2041                kfree(filename);
2042        } else {
2043                rc = ecryptfs_copy_filename(encoded_name,
2044                                            encoded_name_size,
2045                                            name, name_size);
2046        }
2047out:
2048        return rc;
2049}
2050
2051/**
2052 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2053 * @plaintext_name: The plaintext name
2054 * @plaintext_name_size: The plaintext name size
2055 * @ecryptfs_dir_dentry: eCryptfs directory dentry
2056 * @name: The filename in cipher text
2057 * @name_size: The cipher text name size
2058 *
2059 * Decrypts and decodes the filename.
2060 *
2061 * Returns zero on error; non-zero otherwise
2062 */
2063int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2064                                         size_t *plaintext_name_size,
2065                                         struct super_block *sb,
2066                                         const char *name, size_t name_size)
2067{
2068        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2069                &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2070        char *decoded_name;
2071        size_t decoded_name_size;
2072        size_t packet_size;
2073        int rc = 0;
2074
2075        if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2076            && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2077            && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2078            && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2079                        ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2080                const char *orig_name = name;
2081                size_t orig_name_size = name_size;
2082
2083                name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2084                name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2085                ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2086                                              name, name_size);
2087                decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2088                if (!decoded_name) {
2089                        printk(KERN_ERR "%s: Out of memory whilst attempting "
2090                               "to kmalloc [%zd] bytes\n", __func__,
2091                               decoded_name_size);
2092                        rc = -ENOMEM;
2093                        goto out;
2094                }
2095                ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2096                                              name, name_size);
2097                rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2098                                                  plaintext_name_size,
2099                                                  &packet_size,
2100                                                  mount_crypt_stat,
2101                                                  decoded_name,
2102                                                  decoded_name_size);
2103                if (rc) {
2104                        printk(KERN_INFO "%s: Could not parse tag 70 packet "
2105                               "from filename; copying through filename "
2106                               "as-is\n", __func__);
2107                        rc = ecryptfs_copy_filename(plaintext_name,
2108                                                    plaintext_name_size,
2109                                                    orig_name, orig_name_size);
2110                        goto out_free;
2111                }
2112        } else {
2113                rc = ecryptfs_copy_filename(plaintext_name,
2114                                            plaintext_name_size,
2115                                            name, name_size);
2116                goto out;
2117        }
2118out_free:
2119        kfree(decoded_name);
2120out:
2121        return rc;
2122}
2123
2124#define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2125
2126int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2127                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2128{
2129        struct blkcipher_desc desc;
2130        struct mutex *tfm_mutex;
2131        size_t cipher_blocksize;
2132        int rc;
2133
2134        if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2135                (*namelen) = lower_namelen;
2136                return 0;
2137        }
2138
2139        rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2140                        mount_crypt_stat->global_default_fn_cipher_name);
2141        if (unlikely(rc)) {
2142                (*namelen) = 0;
2143                return rc;
2144        }
2145
2146        mutex_lock(tfm_mutex);
2147        cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2148        mutex_unlock(tfm_mutex);
2149
2150        /* Return an exact amount for the common cases */
2151        if (lower_namelen == NAME_MAX
2152            && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2153                (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2154                return 0;
2155        }
2156
2157        /* Return a safe estimate for the uncommon cases */
2158        (*namelen) = lower_namelen;
2159        (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2160        /* Since this is the max decoded size, subtract 1 "decoded block" len */
2161        (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2162        (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2163        (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2164        /* Worst case is that the filename is padded nearly a full block size */
2165        (*namelen) -= cipher_blocksize - 1;
2166
2167        if ((*namelen) < 0)
2168                (*namelen) = 0;
2169
2170        return 0;
2171}
2172
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