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
  40static int
  41ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
  42                             struct page *dst_page, int dst_offset,
  43                             struct page *src_page, int src_offset, int size,
  44                             unsigned char *iv);
  45static int
  46ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
  47                             struct page *dst_page, int dst_offset,
  48                             struct page *src_page, int src_offset, int size,
  49                             unsigned char *iv);
  50
  51/**
  52 * ecryptfs_to_hex
  53 * @dst: Buffer to take hex character representation of contents of
  54 *       src; must be at least of size (src_size * 2)
  55 * @src: Buffer to be converted to a hex string respresentation
  56 * @src_size: number of bytes to convert
  57 */
  58void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
  59{
  60        int x;
  61
  62        for (x = 0; x < src_size; x++)
  63                sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
  64}
  65
  66/**
  67 * ecryptfs_from_hex
  68 * @dst: Buffer to take the bytes from src hex; must be at least of
  69 *       size (src_size / 2)
  70 * @src: Buffer to be converted from a hex string respresentation to raw value
  71 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  72 */
  73void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  74{
  75        int x;
  76        char tmp[3] = { 0, };
  77
  78        for (x = 0; x < dst_size; x++) {
  79                tmp[0] = src[x * 2];
  80                tmp[1] = src[x * 2 + 1];
  81                dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  82        }
  83}
  84
  85/**
  86 * ecryptfs_calculate_md5 - calculates the md5 of @src
  87 * @dst: Pointer to 16 bytes of allocated memory
  88 * @crypt_stat: Pointer to crypt_stat struct for the current inode
  89 * @src: Data to be md5'd
  90 * @len: Length of @src
  91 *
  92 * Uses the allocated crypto context that crypt_stat references to
  93 * generate the MD5 sum of the contents of src.
  94 */
  95static int ecryptfs_calculate_md5(char *dst,
  96                                  struct ecryptfs_crypt_stat *crypt_stat,
  97                                  char *src, int len)
  98{
  99        struct scatterlist sg;
 100        struct hash_desc desc = {
 101                .tfm = crypt_stat->hash_tfm,
 102                .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 103        };
 104        int rc = 0;
 105
 106        mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
 107        sg_init_one(&sg, (u8 *)src, len);
 108        if (!desc.tfm) {
 109                desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
 110                                             CRYPTO_ALG_ASYNC);
 111                if (IS_ERR(desc.tfm)) {
 112                        rc = PTR_ERR(desc.tfm);
 113                        ecryptfs_printk(KERN_ERR, "Error attempting to "
 114                                        "allocate crypto context; rc = [%d]\n",
 115                                        rc);
 116                        goto out;
 117                }
 118                crypt_stat->hash_tfm = desc.tfm;
 119        }
 120        rc = crypto_hash_init(&desc);
 121        if (rc) {
 122                printk(KERN_ERR
 123                       "%s: Error initializing crypto hash; rc = [%d]\n",
 124                       __func__, rc);
 125                goto out;
 126        }
 127        rc = crypto_hash_update(&desc, &sg, len);
 128        if (rc) {
 129                printk(KERN_ERR
 130                       "%s: Error updating crypto hash; rc = [%d]\n",
 131                       __func__, rc);
 132                goto out;
 133        }
 134        rc = crypto_hash_final(&desc, dst);
 135        if (rc) {
 136                printk(KERN_ERR
 137                       "%s: Error finalizing crypto hash; rc = [%d]\n",
 138                       __func__, rc);
 139                goto out;
 140        }
 141out:
 142        mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
 143        return rc;
 144}
 145
 146static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
 147                                                  char *cipher_name,
 148                                                  char *chaining_modifier)
 149{
 150        int cipher_name_len = strlen(cipher_name);
 151        int chaining_modifier_len = strlen(chaining_modifier);
 152        int algified_name_len;
 153        int rc;
 154
 155        algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
 156        (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
 157        if (!(*algified_name)) {
 158                rc = -ENOMEM;
 159                goto out;
 160        }
 161        snprintf((*algified_name), algified_name_len, "%s(%s)",
 162                 chaining_modifier, cipher_name);
 163        rc = 0;
 164out:
 165        return rc;
 166}
 167
 168/**
 169 * ecryptfs_derive_iv
 170 * @iv: destination for the derived iv vale
 171 * @crypt_stat: Pointer to crypt_stat struct for the current inode
 172 * @offset: Offset of the extent whose IV we are to derive
 173 *
 174 * Generate the initialization vector from the given root IV and page
 175 * offset.
 176 *
 177 * Returns zero on success; non-zero on error.
 178 */
 179int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 180                       loff_t offset)
 181{
 182        int rc = 0;
 183        char dst[MD5_DIGEST_SIZE];
 184        char src[ECRYPTFS_MAX_IV_BYTES + 16];
 185
 186        if (unlikely(ecryptfs_verbosity > 0)) {
 187                ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 188                ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 189        }
 190        /* TODO: It is probably secure to just cast the least
 191         * significant bits of the root IV into an unsigned long and
 192         * add the offset to that rather than go through all this
 193         * hashing business. -Halcrow */
 194        memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 195        memset((src + crypt_stat->iv_bytes), 0, 16);
 196        snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
 197        if (unlikely(ecryptfs_verbosity > 0)) {
 198                ecryptfs_printk(KERN_DEBUG, "source:\n");
 199                ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 200        }
 201        rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 202                                    (crypt_stat->iv_bytes + 16));
 203        if (rc) {
 204                ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 205                                "MD5 while generating IV for a page\n");
 206                goto out;
 207        }
 208        memcpy(iv, dst, crypt_stat->iv_bytes);
 209        if (unlikely(ecryptfs_verbosity > 0)) {
 210                ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 211                ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 212        }
 213out:
 214        return rc;
 215}
 216
 217/**
 218 * ecryptfs_init_crypt_stat
 219 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 220 *
 221 * Initialize the crypt_stat structure.
 222 */
 223void
 224ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 225{
 226        memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 227        INIT_LIST_HEAD(&crypt_stat->keysig_list);
 228        mutex_init(&crypt_stat->keysig_list_mutex);
 229        mutex_init(&crypt_stat->cs_mutex);
 230        mutex_init(&crypt_stat->cs_tfm_mutex);
 231        mutex_init(&crypt_stat->cs_hash_tfm_mutex);
 232        crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 233}
 234
 235/**
 236 * ecryptfs_destroy_crypt_stat
 237 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 238 *
 239 * Releases all memory associated with a crypt_stat struct.
 240 */
 241void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 242{
 243        struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 244
 245        if (crypt_stat->tfm)
 246                crypto_free_blkcipher(crypt_stat->tfm);
 247        if (crypt_stat->hash_tfm)
 248                crypto_free_hash(crypt_stat->hash_tfm);
 249        list_for_each_entry_safe(key_sig, key_sig_tmp,
 250                                 &crypt_stat->keysig_list, crypt_stat_list) {
 251                list_del(&key_sig->crypt_stat_list);
 252                kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 253        }
 254        memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 255}
 256
 257void ecryptfs_destroy_mount_crypt_stat(
 258        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 259{
 260        struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 261
 262        if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 263                return;
 264        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 265        list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 266                                 &mount_crypt_stat->global_auth_tok_list,
 267                                 mount_crypt_stat_list) {
 268                list_del(&auth_tok->mount_crypt_stat_list);
 269                if (auth_tok->global_auth_tok_key
 270                    && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 271                        key_put(auth_tok->global_auth_tok_key);
 272                kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 273        }
 274        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 275        memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 276}
 277
 278/**
 279 * virt_to_scatterlist
 280 * @addr: Virtual address
 281 * @size: Size of data; should be an even multiple of the block size
 282 * @sg: Pointer to scatterlist array; set to NULL to obtain only
 283 *      the number of scatterlist structs required in array
 284 * @sg_size: Max array size
 285 *
 286 * Fills in a scatterlist array with page references for a passed
 287 * virtual address.
 288 *
 289 * Returns the number of scatterlist structs in array used
 290 */
 291int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 292                        int sg_size)
 293{
 294        int i = 0;
 295        struct page *pg;
 296        int offset;
 297        int remainder_of_page;
 298
 299        sg_init_table(sg, sg_size);
 300
 301        while (size > 0 && i < sg_size) {
 302                pg = virt_to_page(addr);
 303                offset = offset_in_page(addr);
 304                if (sg)
 305                        sg_set_page(&sg[i], pg, 0, offset);
 306                remainder_of_page = PAGE_CACHE_SIZE - offset;
 307                if (size >= remainder_of_page) {
 308                        if (sg)
 309                                sg[i].length = remainder_of_page;
 310                        addr += remainder_of_page;
 311                        size -= remainder_of_page;
 312                } else {
 313                        if (sg)
 314                                sg[i].length = size;
 315                        addr += size;
 316                        size = 0;
 317                }
 318                i++;
 319        }
 320        if (size > 0)
 321                return -ENOMEM;
 322        return i;
 323}
 324
 325/**
 326 * encrypt_scatterlist
 327 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 328 * @dest_sg: Destination of encrypted data
 329 * @src_sg: Data to be encrypted
 330 * @size: Length of data to be encrypted
 331 * @iv: iv to use during encryption
 332 *
 333 * Returns the number of bytes encrypted; negative value on error
 334 */
 335static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 336                               struct scatterlist *dest_sg,
 337                               struct scatterlist *src_sg, int size,
 338                               unsigned char *iv)
 339{
 340        struct blkcipher_desc desc = {
 341                .tfm = crypt_stat->tfm,
 342                .info = iv,
 343                .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 344        };
 345        int rc = 0;
 346
 347        BUG_ON(!crypt_stat || !crypt_stat->tfm
 348               || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 349        if (unlikely(ecryptfs_verbosity > 0)) {
 350                ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 351                                crypt_stat->key_size);
 352                ecryptfs_dump_hex(crypt_stat->key,
 353                                  crypt_stat->key_size);
 354        }
 355        /* Consider doing this once, when the file is opened */
 356        mutex_lock(&crypt_stat->cs_tfm_mutex);
 357        if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 358                rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 359                                             crypt_stat->key_size);
 360                crypt_stat->flags |= ECRYPTFS_KEY_SET;
 361        }
 362        if (rc) {
 363                ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 364                                rc);
 365                mutex_unlock(&crypt_stat->cs_tfm_mutex);
 366                rc = -EINVAL;
 367                goto out;
 368        }
 369        ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
 370        crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
 371        mutex_unlock(&crypt_stat->cs_tfm_mutex);
 372out:
 373        return rc;
 374}
 375
 376/**
 377 * ecryptfs_lower_offset_for_extent
 378 *
 379 * Convert an eCryptfs page index into a lower byte offset
 380 */
 381static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
 382                                             struct ecryptfs_crypt_stat *crypt_stat)
 383{
 384        (*offset) = ecryptfs_lower_header_size(crypt_stat)
 385                    + (crypt_stat->extent_size * extent_num);
 386}
 387
 388/**
 389 * ecryptfs_encrypt_extent
 390 * @enc_extent_page: Allocated page into which to encrypt the data in
 391 *                   @page
 392 * @crypt_stat: crypt_stat containing cryptographic context for the
 393 *              encryption operation
 394 * @page: Page containing plaintext data extent to encrypt
 395 * @extent_offset: Page extent offset for use in generating IV
 396 *
 397 * Encrypts one extent of data.
 398 *
 399 * Return zero on success; non-zero otherwise
 400 */
 401static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
 402                                   struct ecryptfs_crypt_stat *crypt_stat,
 403                                   struct page *page,
 404                                   unsigned long extent_offset)
 405{
 406        loff_t extent_base;
 407        char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 408        int rc;
 409
 410        extent_base = (((loff_t)page->index)
 411                       * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
 412        rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 413                                (extent_base + extent_offset));
 414        if (rc) {
 415                ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 416                        "extent [0x%.16llx]; rc = [%d]\n",
 417                        (unsigned long long)(extent_base + extent_offset), rc);
 418                goto out;
 419        }
 420        rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
 421                                          page, (extent_offset
 422                                                 * crypt_stat->extent_size),
 423                                          crypt_stat->extent_size, extent_iv);
 424        if (rc < 0) {
 425                printk(KERN_ERR "%s: Error attempting to encrypt page with "
 426                       "page->index = [%ld], extent_offset = [%ld]; "
 427                       "rc = [%d]\n", __func__, page->index, extent_offset,
 428                       rc);
 429                goto out;
 430        }
 431        rc = 0;
 432out:
 433        return rc;
 434}
 435
 436/**
 437 * ecryptfs_encrypt_page
 438 * @page: Page mapped from the eCryptfs inode for the file; contains
 439 *        decrypted content that needs to be encrypted (to a temporary
 440 *        page; not in place) and written out to the lower file
 441 *
 442 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 443 * that eCryptfs pages may straddle the lower pages -- for instance,
 444 * if the file was created on a machine with an 8K page size
 445 * (resulting in an 8K header), and then the file is copied onto a
 446 * host with a 32K page size, then when reading page 0 of the eCryptfs
 447 * file, 24K of page 0 of the lower file will be read and decrypted,
 448 * and then 8K of page 1 of the lower file will be read and decrypted.
 449 *
 450 * Returns zero on success; negative on error
 451 */
 452int ecryptfs_encrypt_page(struct page *page)
 453{
 454        struct inode *ecryptfs_inode;
 455        struct ecryptfs_crypt_stat *crypt_stat;
 456        char *enc_extent_virt;
 457        struct page *enc_extent_page = NULL;
 458        loff_t extent_offset;
 459        int rc = 0;
 460
 461        ecryptfs_inode = page->mapping->host;
 462        crypt_stat =
 463                &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 464        BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 465        enc_extent_page = alloc_page(GFP_USER);
 466        if (!enc_extent_page) {
 467                rc = -ENOMEM;
 468                ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 469                                "encrypted extent\n");
 470                goto out;
 471        }
 472        enc_extent_virt = kmap(enc_extent_page);
 473        for (extent_offset = 0;
 474             extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 475             extent_offset++) {
 476                loff_t offset;
 477
 478                rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
 479                                             extent_offset);
 480                if (rc) {
 481                        printk(KERN_ERR "%s: Error encrypting extent; "
 482                               "rc = [%d]\n", __func__, rc);
 483                        goto out;
 484                }
 485                ecryptfs_lower_offset_for_extent(
 486                        &offset, ((((loff_t)page->index)
 487                                   * (PAGE_CACHE_SIZE
 488                                      / crypt_stat->extent_size))
 489                                  + extent_offset), crypt_stat);
 490                rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
 491                                          offset, crypt_stat->extent_size);
 492                if (rc < 0) {
 493                        ecryptfs_printk(KERN_ERR, "Error attempting "
 494                                        "to write lower page; rc = [%d]"
 495                                        "\n", rc);
 496                        goto out;
 497                }
 498        }
 499        rc = 0;
 500out:
 501        if (enc_extent_page) {
 502                kunmap(enc_extent_page);
 503                __free_page(enc_extent_page);
 504        }
 505        return rc;
 506}
 507
 508static int ecryptfs_decrypt_extent(struct page *page,
 509                                   struct ecryptfs_crypt_stat *crypt_stat,
 510                                   struct page *enc_extent_page,
 511                                   unsigned long extent_offset)
 512{
 513        loff_t extent_base;
 514        char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 515        int rc;
 516
 517        extent_base = (((loff_t)page->index)
 518                       * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
 519        rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 520                                (extent_base + extent_offset));
 521        if (rc) {
 522                ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 523                        "extent [0x%.16llx]; rc = [%d]\n",
 524                        (unsigned long long)(extent_base + extent_offset), rc);
 525                goto out;
 526        }
 527        rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
 528                                          (extent_offset
 529                                           * crypt_stat->extent_size),
 530                                          enc_extent_page, 0,
 531                                          crypt_stat->extent_size, extent_iv);
 532        if (rc < 0) {
 533                printk(KERN_ERR "%s: Error attempting to decrypt to page with "
 534                       "page->index = [%ld], extent_offset = [%ld]; "
 535                       "rc = [%d]\n", __func__, page->index, extent_offset,
 536                       rc);
 537                goto out;
 538        }
 539        rc = 0;
 540out:
 541        return rc;
 542}
 543
 544/**
 545 * ecryptfs_decrypt_page
 546 * @page: Page mapped from the eCryptfs inode for the file; data read
 547 *        and decrypted from the lower file will be written into this
 548 *        page
 549 *
 550 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 551 * that eCryptfs pages may straddle the lower pages -- for instance,
 552 * if the file was created on a machine with an 8K page size
 553 * (resulting in an 8K header), and then the file is copied onto a
 554 * host with a 32K page size, then when reading page 0 of the eCryptfs
 555 * file, 24K of page 0 of the lower file will be read and decrypted,
 556 * and then 8K of page 1 of the lower file will be read and decrypted.
 557 *
 558 * Returns zero on success; negative on error
 559 */
 560int ecryptfs_decrypt_page(struct page *page)
 561{
 562        struct inode *ecryptfs_inode;
 563        struct ecryptfs_crypt_stat *crypt_stat;
 564        char *enc_extent_virt;
 565        struct page *enc_extent_page = NULL;
 566        unsigned long extent_offset;
 567        int rc = 0;
 568
 569        ecryptfs_inode = page->mapping->host;
 570        crypt_stat =
 571                &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 572        BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 573        enc_extent_page = alloc_page(GFP_USER);
 574        if (!enc_extent_page) {
 575                rc = -ENOMEM;
 576                ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 577                                "encrypted extent\n");
 578                goto out;
 579        }
 580        enc_extent_virt = kmap(enc_extent_page);
 581        for (extent_offset = 0;
 582             extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 583             extent_offset++) {
 584                loff_t offset;
 585
 586                ecryptfs_lower_offset_for_extent(
 587                        &offset, ((page->index * (PAGE_CACHE_SIZE
 588                                                  / crypt_stat->extent_size))
 589                                  + extent_offset), crypt_stat);
 590                rc = ecryptfs_read_lower(enc_extent_virt, offset,
 591                                         crypt_stat->extent_size,
 592                                         ecryptfs_inode);
 593                if (rc < 0) {
 594                        ecryptfs_printk(KERN_ERR, "Error attempting "
 595                                        "to read lower page; rc = [%d]"
 596                                        "\n", rc);
 597                        goto out;
 598                }
 599                rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
 600                                             extent_offset);
 601                if (rc) {
 602                        printk(KERN_ERR "%s: Error encrypting extent; "
 603                               "rc = [%d]\n", __func__, rc);
 604                        goto out;
 605                }
 606        }
 607out:
 608        if (enc_extent_page) {
 609                kunmap(enc_extent_page);
 610                __free_page(enc_extent_page);
 611        }
 612        return rc;
 613}
 614
 615/**
 616 * decrypt_scatterlist
 617 * @crypt_stat: Cryptographic context
 618 * @dest_sg: The destination scatterlist to decrypt into
 619 * @src_sg: The source scatterlist to decrypt from
 620 * @size: The number of bytes to decrypt
 621 * @iv: The initialization vector to use for the decryption
 622 *
 623 * Returns the number of bytes decrypted; negative value on error
 624 */
 625static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 626                               struct scatterlist *dest_sg,
 627                               struct scatterlist *src_sg, int size,
 628                               unsigned char *iv)
 629{
 630        struct blkcipher_desc desc = {
 631                .tfm = crypt_stat->tfm,
 632                .info = iv,
 633                .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 634        };
 635        int rc = 0;
 636
 637        /* Consider doing this once, when the file is opened */
 638        mutex_lock(&crypt_stat->cs_tfm_mutex);
 639        rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 640                                     crypt_stat->key_size);
 641        if (rc) {
 642                ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 643                                rc);
 644                mutex_unlock(&crypt_stat->cs_tfm_mutex);
 645                rc = -EINVAL;
 646                goto out;
 647        }
 648        ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
 649        rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
 650        mutex_unlock(&crypt_stat->cs_tfm_mutex);
 651        if (rc) {
 652                ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
 653                                rc);
 654                goto out;
 655        }
 656        rc = size;
 657out:
 658        return rc;
 659}
 660
 661/**
 662 * ecryptfs_encrypt_page_offset
 663 * @crypt_stat: The cryptographic context
 664 * @dst_page: The page to encrypt into
 665 * @dst_offset: The offset in the page to encrypt into
 666 * @src_page: The page to encrypt from
 667 * @src_offset: The offset in the page to encrypt from
 668 * @size: The number of bytes to encrypt
 669 * @iv: The initialization vector to use for the encryption
 670 *
 671 * Returns the number of bytes encrypted
 672 */
 673static int
 674ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 675                             struct page *dst_page, int dst_offset,
 676                             struct page *src_page, int src_offset, int size,
 677                             unsigned char *iv)
 678{
 679        struct scatterlist src_sg, dst_sg;
 680
 681        sg_init_table(&src_sg, 1);
 682        sg_init_table(&dst_sg, 1);
 683
 684        sg_set_page(&src_sg, src_page, size, src_offset);
 685        sg_set_page(&dst_sg, dst_page, size, dst_offset);
 686        return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 687}
 688
 689/**
 690 * ecryptfs_decrypt_page_offset
 691 * @crypt_stat: The cryptographic context
 692 * @dst_page: The page to decrypt into
 693 * @dst_offset: The offset in the page to decrypt into
 694 * @src_page: The page to decrypt from
 695 * @src_offset: The offset in the page to decrypt from
 696 * @size: The number of bytes to decrypt
 697 * @iv: The initialization vector to use for the decryption
 698 *
 699 * Returns the number of bytes decrypted
 700 */
 701static int
 702ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 703                             struct page *dst_page, int dst_offset,
 704                             struct page *src_page, int src_offset, int size,
 705                             unsigned char *iv)
 706{
 707        struct scatterlist src_sg, dst_sg;
 708
 709        sg_init_table(&src_sg, 1);
 710        sg_set_page(&src_sg, src_page, size, src_offset);
 711
 712        sg_init_table(&dst_sg, 1);
 713        sg_set_page(&dst_sg, dst_page, size, dst_offset);
 714
 715        return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 716}
 717
 718#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 719
 720/**
 721 * ecryptfs_init_crypt_ctx
 722 * @crypt_stat: Uninitialized crypt stats structure
 723 *
 724 * Initialize the crypto context.
 725 *
 726 * TODO: Performance: Keep a cache of initialized cipher contexts;
 727 * only init if needed
 728 */
 729int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 730{
 731        char *full_alg_name;
 732        int rc = -EINVAL;
 733
 734        if (!crypt_stat->cipher) {
 735                ecryptfs_printk(KERN_ERR, "No cipher specified\n");
 736                goto out;
 737        }
 738        ecryptfs_printk(KERN_DEBUG,
 739                        "Initializing cipher [%s]; strlen = [%d]; "
 740                        "key_size_bits = [%zd]\n",
 741                        crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 742                        crypt_stat->key_size << 3);
 743        if (crypt_stat->tfm) {
 744                rc = 0;
 745                goto out;
 746        }
 747        mutex_lock(&crypt_stat->cs_tfm_mutex);
 748        rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 749                                                    crypt_stat->cipher, "cbc");
 750        if (rc)
 751                goto out_unlock;
 752        crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
 753                                                 CRYPTO_ALG_ASYNC);
 754        kfree(full_alg_name);
 755        if (IS_ERR(crypt_stat->tfm)) {
 756                rc = PTR_ERR(crypt_stat->tfm);
 757                crypt_stat->tfm = NULL;
 758                ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 759                                "Error initializing cipher [%s]\n",
 760                                crypt_stat->cipher);
 761                goto out_unlock;
 762        }
 763        crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 764        rc = 0;
 765out_unlock:
 766        mutex_unlock(&crypt_stat->cs_tfm_mutex);
 767out:
 768        return rc;
 769}
 770
 771static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 772{
 773        int extent_size_tmp;
 774
 775        crypt_stat->extent_mask = 0xFFFFFFFF;
 776        crypt_stat->extent_shift = 0;
 777        if (crypt_stat->extent_size == 0)
 778                return;
 779        extent_size_tmp = crypt_stat->extent_size;
 780        while ((extent_size_tmp & 0x01) == 0) {
 781                extent_size_tmp >>= 1;
 782                crypt_stat->extent_mask <<= 1;
 783                crypt_stat->extent_shift++;
 784        }
 785}
 786
 787void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 788{
 789        /* Default values; may be overwritten as we are parsing the
 790         * packets. */
 791        crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 792        set_extent_mask_and_shift(crypt_stat);
 793        crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 794        if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 795                crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 796        else {
 797                if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 798                        crypt_stat->metadata_size =
 799                                ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 800                else
 801                        crypt_stat->metadata_size = PAGE_CACHE_SIZE;
 802        }
 803}
 804
 805/**
 806 * ecryptfs_compute_root_iv
 807 * @crypt_stats
 808 *
 809 * On error, sets the root IV to all 0's.
 810 */
 811int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 812{
 813        int rc = 0;
 814        char dst[MD5_DIGEST_SIZE];
 815
 816        BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 817        BUG_ON(crypt_stat->iv_bytes <= 0);
 818        if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 819                rc = -EINVAL;
 820                ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 821                                "cannot generate root IV\n");
 822                goto out;
 823        }
 824        rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 825                                    crypt_stat->key_size);
 826        if (rc) {
 827                ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 828                                "MD5 while generating root IV\n");
 829                goto out;
 830        }
 831        memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 832out:
 833        if (rc) {
 834                memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 835                crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 836        }
 837        return rc;
 838}
 839
 840static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 841{
 842        get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 843        crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 844        ecryptfs_compute_root_iv(crypt_stat);
 845        if (unlikely(ecryptfs_verbosity > 0)) {
 846                ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 847                ecryptfs_dump_hex(crypt_stat->key,
 848                                  crypt_stat->key_size);
 849        }
 850}
 851
 852/**
 853 * ecryptfs_copy_mount_wide_flags_to_inode_flags
 854 * @crypt_stat: The inode's cryptographic context
 855 * @mount_crypt_stat: The mount point's cryptographic context
 856 *
 857 * This function propagates the mount-wide flags to individual inode
 858 * flags.
 859 */
 860static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 861        struct ecryptfs_crypt_stat *crypt_stat,
 862        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 863{
 864        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 865                crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 866        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 867                crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 868        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 869                crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 870                if (mount_crypt_stat->flags
 871                    & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 872                        crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 873                else if (mount_crypt_stat->flags
 874                         & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 875                        crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 876        }
 877}
 878
 879static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 880        struct ecryptfs_crypt_stat *crypt_stat,
 881        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 882{
 883        struct ecryptfs_global_auth_tok *global_auth_tok;
 884        int rc = 0;
 885
 886        mutex_lock(&crypt_stat->keysig_list_mutex);
 887        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 888
 889        list_for_each_entry(global_auth_tok,
 890                            &mount_crypt_stat->global_auth_tok_list,
 891                            mount_crypt_stat_list) {
 892                if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 893                        continue;
 894                rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 895                if (rc) {
 896                        printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 897                        goto out;
 898                }
 899        }
 900
 901out:
 902        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 903        mutex_unlock(&crypt_stat->keysig_list_mutex);
 904        return rc;
 905}
 906
 907/**
 908 * ecryptfs_set_default_crypt_stat_vals
 909 * @crypt_stat: The inode's cryptographic context
 910 * @mount_crypt_stat: The mount point's cryptographic context
 911 *
 912 * Default values in the event that policy does not override them.
 913 */
 914static void ecryptfs_set_default_crypt_stat_vals(
 915        struct ecryptfs_crypt_stat *crypt_stat,
 916        struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 917{
 918        ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 919                                                      mount_crypt_stat);
 920        ecryptfs_set_default_sizes(crypt_stat);
 921        strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 922        crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 923        crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 924        crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 925        crypt_stat->mount_crypt_stat = mount_crypt_stat;
 926}
 927
 928/**
 929 * ecryptfs_new_file_context
 930 * @ecryptfs_inode: The eCryptfs inode
 931 *
 932 * If the crypto context for the file has not yet been established,
 933 * this is where we do that.  Establishing a new crypto context
 934 * involves the following decisions:
 935 *  - What cipher to use?
 936 *  - What set of authentication tokens to use?
 937 * Here we just worry about getting enough information into the
 938 * authentication tokens so that we know that they are available.
 939 * We associate the available authentication tokens with the new file
 940 * via the set of signatures in the crypt_stat struct.  Later, when
 941 * the headers are actually written out, we may again defer to
 942 * userspace to perform the encryption of the session key; for the
 943 * foreseeable future, this will be the case with public key packets.
 944 *
 945 * Returns zero on success; non-zero otherwise
 946 */
 947int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 948{
 949        struct ecryptfs_crypt_stat *crypt_stat =
 950            &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 951        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 952            &ecryptfs_superblock_to_private(
 953                    ecryptfs_inode->i_sb)->mount_crypt_stat;
 954        int cipher_name_len;
 955        int rc = 0;
 956
 957        ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 958        crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 959        ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 960                                                      mount_crypt_stat);
 961        rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 962                                                         mount_crypt_stat);
 963        if (rc) {
 964                printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 965                       "to the inode key sigs; rc = [%d]\n", rc);
 966                goto out;
 967        }
 968        cipher_name_len =
 969                strlen(mount_crypt_stat->global_default_cipher_name);
 970        memcpy(crypt_stat->cipher,
 971               mount_crypt_stat->global_default_cipher_name,
 972               cipher_name_len);
 973        crypt_stat->cipher[cipher_name_len] = '\0';
 974        crypt_stat->key_size =
 975                mount_crypt_stat->global_default_cipher_key_size;
 976        ecryptfs_generate_new_key(crypt_stat);
 977        rc = ecryptfs_init_crypt_ctx(crypt_stat);
 978        if (rc)
 979                ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 980                                "context for cipher [%s]: rc = [%d]\n",
 981                                crypt_stat->cipher, rc);
 982out:
 983        return rc;
 984}
 985
 986/**
 987 * ecryptfs_validate_marker - check for the ecryptfs marker
 988 * @data: The data block in which to check
 989 *
 990 * Returns zero if marker found; -EINVAL if not found
 991 */
 992static int ecryptfs_validate_marker(char *data)
 993{
 994        u32 m_1, m_2;
 995
 996        m_1 = get_unaligned_be32(data);
 997        m_2 = get_unaligned_be32(data + 4);
 998        if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 999                return 0;
1000        ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1001                        "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1002                        MAGIC_ECRYPTFS_MARKER);
1003        ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1004                        "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1005        return -EINVAL;
1006}
1007
1008struct ecryptfs_flag_map_elem {
1009        u32 file_flag;
1010        u32 local_flag;
1011};
1012
1013/* Add support for additional flags by adding elements here. */
1014static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1015        {0x00000001, ECRYPTFS_ENABLE_HMAC},
1016        {0x00000002, ECRYPTFS_ENCRYPTED},
1017        {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1018        {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1019};
1020
1021/**
1022 * ecryptfs_process_flags
1023 * @crypt_stat: The cryptographic context
1024 * @page_virt: Source data to be parsed
1025 * @bytes_read: Updated with the number of bytes read
1026 *
1027 * Returns zero on success; non-zero if the flag set is invalid
1028 */
1029static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1030                                  char *page_virt, int *bytes_read)
1031{
1032        int rc = 0;
1033        int i;
1034        u32 flags;
1035
1036        flags = get_unaligned_be32(page_virt);
1037        for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1038                          / sizeof(struct ecryptfs_flag_map_elem))); i++)
1039                if (flags & ecryptfs_flag_map[i].file_flag) {
1040                        crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1041                } else
1042                        crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1043        /* Version is in top 8 bits of the 32-bit flag vector */
1044        crypt_stat->file_version = ((flags >> 24) & 0xFF);
1045        (*bytes_read) = 4;
1046        return rc;
1047}
1048
1049/**
1050 * write_ecryptfs_marker
1051 * @page_virt: The pointer to in a page to begin writing the marker
1052 * @written: Number of bytes written
1053 *
1054 * Marker = 0x3c81b7f5
1055 */
1056static void write_ecryptfs_marker(char *page_virt, size_t *written)
1057{
1058        u32 m_1, m_2;
1059
1060        get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1061        m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1062        put_unaligned_be32(m_1, page_virt);
1063        page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1064        put_unaligned_be32(m_2, page_virt);
1065        (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1066}
1067
1068void ecryptfs_write_crypt_stat_flags(char *page_virt,
1069                                     struct ecryptfs_crypt_stat *crypt_stat,
1070                                     size_t *written)
1071{
1072        u32 flags = 0;
1073        int i;
1074
1075        for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1076                          / sizeof(struct ecryptfs_flag_map_elem))); i++)
1077                if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1078                        flags |= ecryptfs_flag_map[i].file_flag;
1079        /* Version is in top 8 bits of the 32-bit flag vector */
1080        flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1081        put_unaligned_be32(flags, page_virt);
1082        (*written) = 4;
1083}
1084
1085struct ecryptfs_cipher_code_str_map_elem {
1086        char cipher_str[16];
1087        u8 cipher_code;
1088};
1089
1090/* Add support for additional ciphers by adding elements here. The
1091 * cipher_code is whatever OpenPGP applicatoins use to identify the
1092 * ciphers. List in order of probability. */
1093static struct ecryptfs_cipher_code_str_map_elem
1094ecryptfs_cipher_code_str_map[] = {
1095        {"aes",RFC2440_CIPHER_AES_128 },
1096        {"blowfish", RFC2440_CIPHER_BLOWFISH},
1097        {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1098        {"cast5", RFC2440_CIPHER_CAST_5},
1099        {"twofish", RFC2440_CIPHER_TWOFISH},
1100        {"cast6", RFC2440_CIPHER_CAST_6},
1101        {"aes", RFC2440_CIPHER_AES_192},
1102        {"aes", RFC2440_CIPHER_AES_256}
1103};
1104
1105/**
1106 * ecryptfs_code_for_cipher_string
1107 * @cipher_name: The string alias for the cipher
1108 * @key_bytes: Length of key in bytes; used for AES code selection
1109 *
1110 * Returns zero on no match, or the cipher code on match
1111 */
1112u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1113{
1114        int i;
1115        u8 code = 0;
1116        struct ecryptfs_cipher_code_str_map_elem *map =
1117                ecryptfs_cipher_code_str_map;
1118
1119        if (strcmp(cipher_name, "aes") == 0) {
1120                switch (key_bytes) {
1121                case 16:
1122                        code = RFC2440_CIPHER_AES_128;
1123                        break;
1124                case 24:
1125                        code = RFC2440_CIPHER_AES_192;
1126                        break;
1127                case 32:
1128                        code = RFC2440_CIPHER_AES_256;
1129                }
1130        } else {
1131                for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1132                        if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1133                                code = map[i].cipher_code;
1134                                break;
1135                        }
1136        }
1137        return code;
1138}
1139
1140/**
1141 * ecryptfs_cipher_code_to_string
1142 * @str: Destination to write out the cipher name
1143 * @cipher_code: The code to convert to cipher name string
1144 *
1145 * Returns zero on success
1146 */
1147int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1148{
1149        int rc = 0;
1150        int i;
1151
1152        str[0] = '\0';
1153        for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1154                if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1155                        strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1156        if (str[0] == '\0') {
1157                ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1158                                "[%d]\n", cipher_code);
1159                rc = -EINVAL;
1160        }
1161        return rc;
1162}
1163
1164int ecryptfs_read_and_validate_header_region(struct inode *inode)
1165{
1166        u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1167        u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1168        int rc;
1169
1170        rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1171                                 inode);
1172        if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1173                return rc >= 0 ? -EINVAL : rc;
1174        rc = ecryptfs_validate_marker(marker);
1175        if (!rc)
1176                ecryptfs_i_size_init(file_size, inode);
1177        return rc;
1178}
1179
1180void
1181ecryptfs_write_header_metadata(char *virt,
1182                               struct ecryptfs_crypt_stat *crypt_stat,
1183                               size_t *written)
1184{
1185        u32 header_extent_size;
1186        u16 num_header_extents_at_front;
1187
1188        header_extent_size = (u32)crypt_stat->extent_size;
1189        num_header_extents_at_front =
1190                (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1191        put_unaligned_be32(header_extent_size, virt);
1192        virt += 4;
1193        put_unaligned_be16(num_header_extents_at_front, virt);
1194        (*written) = 6;
1195}
1196
1197struct kmem_cache *ecryptfs_header_cache;
1198
1199/**
1200 * ecryptfs_write_headers_virt
1201 * @page_virt: The virtual address to write the headers to
1202 * @max: The size of memory allocated at page_virt
1203 * @size: Set to the number of bytes written by this function
1204 * @crypt_stat: The cryptographic context
1205 * @ecryptfs_dentry: The eCryptfs dentry
1206 *
1207 * Format version: 1
1208 *
1209 *   Header Extent:
1210 *     Octets 0-7:        Unencrypted file size (big-endian)
1211 *     Octets 8-15:       eCryptfs special marker
1212 *     Octets 16-19:      Flags
1213 *      Octet 16:         File format version number (between 0 and 255)
1214 *      Octets 17-18:     Reserved
1215 *      Octet 19:         Bit 1 (lsb): Reserved
1216 *                        Bit 2: Encrypted?
1217 *                        Bits 3-8: Reserved
1218 *     Octets 20-23:      Header extent size (big-endian)
1219 *     Octets 24-25:      Number of header extents at front of file
1220 *                        (big-endian)
1221 *     Octet  26:         Begin RFC 2440 authentication token packet set
1222 *   Data Extent 0:
1223 *     Lower data (CBC encrypted)
1224 *   Data Extent 1:
1225 *     Lower data (CBC encrypted)
1226 *   ...
1227 *
1228 * Returns zero on success
1229 */
1230static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1231                                       size_t *size,
1232                                       struct ecryptfs_crypt_stat *crypt_stat,
1233                                       struct dentry *ecryptfs_dentry)
1234{
1235        int rc;
1236        size_t written;
1237        size_t offset;
1238
1239        offset = ECRYPTFS_FILE_SIZE_BYTES;
1240        write_ecryptfs_marker((page_virt + offset), &written);
1241        offset += written;
1242        ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1243                                        &written);
1244        offset += written;
1245        ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1246                                       &written);
1247        offset += written;
1248        rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1249                                              ecryptfs_dentry, &written,
1250                                              max - offset);
1251        if (rc)
1252                ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1253                                "set; rc = [%d]\n", rc);
1254        if (size) {
1255                offset += written;
1256                *size = offset;
1257        }
1258        return rc;
1259}
1260
1261static int
1262ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1263                                    char *virt, size_t virt_len)
1264{
1265        int rc;
1266
1267        rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1268                                  0, virt_len);
1269        if (rc < 0)
1270                printk(KERN_ERR "%s: Error attempting to write header "
1271                       "information to lower file; rc = [%d]\n", __func__, rc);
1272        else
1273                rc = 0;
1274        return rc;
1275}
1276
1277static int
1278ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1279                                 char *page_virt, size_t size)
1280{
1281        int rc;
1282
1283        rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1284                               size, 0);
1285        return rc;
1286}
1287
1288static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1289                                               unsigned int order)
1290{
1291        struct page *page;
1292
1293        page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1294        if (page)
1295                return (unsigned long) page_address(page);
1296        return 0;
1297}
1298
1299/**
1300 * ecryptfs_write_metadata
1301 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1302 * @ecryptfs_inode: The newly created eCryptfs inode
1303 *
1304 * Write the file headers out.  This will likely involve a userspace
1305 * callout, in which the session key is encrypted with one or more
1306 * public keys and/or the passphrase necessary to do the encryption is
1307 * retrieved via a prompt.  Exactly what happens at this point should
1308 * be policy-dependent.
1309 *
1310 * Returns zero on success; non-zero on error
1311 */
1312int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1313                            struct inode *ecryptfs_inode)
1314{
1315        struct ecryptfs_crypt_stat *crypt_stat =
1316                &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1317        unsigned int order;
1318        char *virt;
1319        size_t virt_len;
1320        size_t size = 0;
1321        int rc = 0;
1322
1323        if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1324                if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1325                        printk(KERN_ERR "Key is invalid; bailing out\n");
1326                        rc = -EINVAL;
1327                        goto out;
1328                }
1329        } else {
1330                printk(KERN_WARNING "%s: Encrypted flag not set\n",
1331                       __func__);
1332                rc = -EINVAL;
1333                goto out;
1334        }
1335        virt_len = crypt_stat->metadata_size;
1336        order = get_order(virt_len);
1337        /* Released in this function */
1338        virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1339        if (!virt) {
1340                printk(KERN_ERR "%s: Out of memory\n", __func__);
1341                rc = -ENOMEM;
1342                goto out;
1343        }
1344        /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1345        rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1346                                         ecryptfs_dentry);
1347        if (unlikely(rc)) {
1348                printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1349                       __func__, rc);
1350                goto out_free;
1351        }
1352        if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1353                rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1354                                                      size);
1355        else
1356                rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1357                                                         virt_len);
1358        if (rc) {
1359                printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1360                       "rc = [%d]\n", __func__, rc);
1361                goto out_free;
1362        }
1363out_free:
1364        free_pages((unsigned long)virt, order);
1365out:
1366        return rc;
1367}
1368
1369#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1370#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1371static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1372                                 char *virt, int *bytes_read,
1373                                 int validate_header_size)
1374{
1375        int rc = 0;
1376        u32 header_extent_size;
1377        u16 num_header_extents_at_front;
1378
1379        header_extent_size = get_unaligned_be32(virt);
1380        virt += sizeof(__be32);
1381        num_header_extents_at_front = get_unaligned_be16(virt);
1382        crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1383                                     * (size_t)header_extent_size));
1384        (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1385        if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1386            && (crypt_stat->metadata_size
1387                < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1388                rc = -EINVAL;
1389                printk(KERN_WARNING "Invalid header size: [%zd]\n",
1390                       crypt_stat->metadata_size);
1391        }
1392        return rc;
1393}
1394
1395/**
1396 * set_default_header_data
1397 * @crypt_stat: The cryptographic context
1398 *
1399 * For version 0 file format; this function is only for backwards
1400 * compatibility for files created with the prior versions of
1401 * eCryptfs.
1402 */
1403static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1404{
1405        crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1406}
1407
1408void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1409{
1410        struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1411        struct ecryptfs_crypt_stat *crypt_stat;
1412        u64 file_size;
1413
1414        crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1415        mount_crypt_stat =
1416                &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1417        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1418                file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1419                if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1420                        file_size += crypt_stat->metadata_size;
1421        } else
1422                file_size = get_unaligned_be64(page_virt);
1423        i_size_write(inode, (loff_t)file_size);
1424        crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1425}
1426
1427/**
1428 * ecryptfs_read_headers_virt
1429 * @page_virt: The virtual address into which to read the headers
1430 * @crypt_stat: The cryptographic context
1431 * @ecryptfs_dentry: The eCryptfs dentry
1432 * @validate_header_size: Whether to validate the header size while reading
1433 *
1434 * Read/parse the header data. The header format is detailed in the
1435 * comment block for the ecryptfs_write_headers_virt() function.
1436 *
1437 * Returns zero on success
1438 */
1439static int ecryptfs_read_headers_virt(char *page_virt,
1440                                      struct ecryptfs_crypt_stat *crypt_stat,
1441                                      struct dentry *ecryptfs_dentry,
1442                                      int validate_header_size)
1443{
1444        int rc = 0;
1445        int offset;
1446        int bytes_read;
1447
1448        ecryptfs_set_default_sizes(crypt_stat);
1449        crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1450                ecryptfs_dentry->d_sb)->mount_crypt_stat;
1451        offset = ECRYPTFS_FILE_SIZE_BYTES;
1452        rc = ecryptfs_validate_marker(page_virt + offset);
1453        if (rc)
1454                goto out;
1455        if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1456                ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1457        offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1458        rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1459                                    &bytes_read);
1460        if (rc) {
1461                ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1462                goto out;
1463        }
1464        if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1465                ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1466                                "file version [%d] is supported by this "
1467                                "version of eCryptfs\n",
1468                                crypt_stat->file_version,
1469                                ECRYPTFS_SUPPORTED_FILE_VERSION);
1470                rc = -EINVAL;
1471                goto out;
1472        }
1473        offset += bytes_read;
1474        if (crypt_stat->file_version >= 1) {
1475                rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1476                                           &bytes_read, validate_header_size);
1477                if (rc) {
1478                        ecryptfs_printk(KERN_WARNING, "Error reading header "
1479                                        "metadata; rc = [%d]\n", rc);
1480                }
1481                offset += bytes_read;
1482        } else
1483                set_default_header_data(crypt_stat);
1484        rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1485                                       ecryptfs_dentry);
1486out:
1487        return rc;
1488}
1489
1490/**
1491 * ecryptfs_read_xattr_region
1492 * @page_virt: The vitual address into which to read the xattr data
1493 * @ecryptfs_inode: The eCryptfs inode
1494 *
1495 * Attempts to read the crypto metadata from the extended attribute
1496 * region of the lower file.
1497 *
1498 * Returns zero on success; non-zero on error
1499 */
1500int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1501{
1502        struct dentry *lower_dentry =
1503                ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1504        ssize_t size;
1505        int rc = 0;
1506
1507        size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1508                                       page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1509        if (size < 0) {
1510                if (unlikely(ecryptfs_verbosity > 0))
1511                        printk(KERN_INFO "Error attempting to read the [%s] "
1512                               "xattr from the lower file; return value = "
1513                               "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1514                rc = -EINVAL;
1515                goto out;
1516        }
1517out:
1518        return rc;
1519}
1520
1521int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1522                                            struct inode *inode)
1523{
1524        u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1525        u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1526        int rc;
1527
1528        rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1529                                     ECRYPTFS_XATTR_NAME, file_size,
1530                                     ECRYPTFS_SIZE_AND_MARKER_BYTES);
1531        if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1532                return rc >= 0 ? -EINVAL : rc;
1533        rc = ecryptfs_validate_marker(marker);
1534        if (!rc)
1535                ecryptfs_i_size_init(file_size, inode);
1536        return rc;
1537}
1538
1539/**
1540 * ecryptfs_read_metadata
1541 *
1542 * Common entry point for reading file metadata. From here, we could
1543 * retrieve the header information from the header region of the file,
1544 * the xattr region of the file, or some other repostory that is
1545 * stored separately from the file itself. The current implementation
1546 * supports retrieving the metadata information from the file contents
1547 * and from the xattr region.
1548 *
1549 * Returns zero if valid headers found and parsed; non-zero otherwise
1550 */
1551int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1552{
1553        int rc;
1554        char *page_virt;
1555        struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1556        struct ecryptfs_crypt_stat *crypt_stat =
1557            &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1558        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1559                &ecryptfs_superblock_to_private(
1560                        ecryptfs_dentry->d_sb)->mount_crypt_stat;
1561
1562        ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1563                                                      mount_crypt_stat);
1564        /* Read the first page from the underlying file */
1565        page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1566        if (!page_virt) {
1567                rc = -ENOMEM;
1568                printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1569                       __func__);
1570                goto out;
1571        }
1572        rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1573                                 ecryptfs_inode);
1574        if (rc >= 0)
1575                rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1576                                                ecryptfs_dentry,
1577                                                ECRYPTFS_VALIDATE_HEADER_SIZE);
1578        if (rc) {
1579                /* metadata is not in the file header, so try xattrs */
1580                memset(page_virt, 0, PAGE_CACHE_SIZE);
1581                rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1582                if (rc) {
1583                        printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1584                               "file header region or xattr region, inode %lu\n",
1585                                ecryptfs_inode->i_ino);
1586                        rc = -EINVAL;
1587                        goto out;
1588                }
1589                rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1590                                                ecryptfs_dentry,
1591                                                ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1592                if (rc) {
1593                        printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1594                               "file xattr region either, inode %lu\n",
1595                                ecryptfs_inode->i_ino);
1596                        rc = -EINVAL;
1597                }
1598                if (crypt_stat->mount_crypt_stat->flags
1599                    & ECRYPTFS_XATTR_METADATA_ENABLED) {
1600                        crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1601                } else {
1602                        printk(KERN_WARNING "Attempt to access file with "
1603                               "crypto metadata only in the extended attribute "
1604                               "region, but eCryptfs was mounted without "
1605                               "xattr support enabled. eCryptfs will not treat "
1606                               "this like an encrypted file, inode %lu\n",
1607                                ecryptfs_inode->i_ino);
1608                        rc = -EINVAL;
1609                }
1610        }
1611out:
1612        if (page_virt) {
1613                memset(page_virt, 0, PAGE_CACHE_SIZE);
1614                kmem_cache_free(ecryptfs_header_cache, page_virt);
1615        }
1616        return rc;
1617}
1618
1619/**
1620 * ecryptfs_encrypt_filename - encrypt filename
1621 *
1622 * CBC-encrypts the filename. We do not want to encrypt the same
1623 * filename with the same key and IV, which may happen with hard
1624 * links, so we prepend random bits to each filename.
1625 *
1626 * Returns zero on success; non-zero otherwise
1627 */
1628static int
1629ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1630                          struct ecryptfs_crypt_stat *crypt_stat,
1631                          struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1632{
1633        int rc = 0;
1634
1635        filename->encrypted_filename = NULL;
1636        filename->encrypted_filename_size = 0;
1637        if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1638            || (mount_crypt_stat && (mount_crypt_stat->flags
1639                                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1640                size_t packet_size;
1641                size_t remaining_bytes;
1642
1643                rc = ecryptfs_write_tag_70_packet(
1644                        NULL, NULL,
1645                        &filename->encrypted_filename_size,
1646                        mount_crypt_stat, NULL,
1647                        filename->filename_size);
1648                if (rc) {
1649                        printk(KERN_ERR "%s: Error attempting to get packet "
1650                               "size for tag 72; rc = [%d]\n", __func__,
1651                               rc);
1652                        filename->encrypted_filename_size = 0;
1653                        goto out;
1654                }
1655                filename->encrypted_filename =
1656                        kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1657                if (!filename->encrypted_filename) {
1658                        printk(KERN_ERR "%s: Out of memory whilst attempting "
1659                               "to kmalloc [%zd] bytes\n", __func__,
1660                               filename->encrypted_filename_size);
1661                        rc = -ENOMEM;
1662                        goto out;
1663                }
1664                remaining_bytes = filename->encrypted_filename_size;
1665                rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1666                                                  &remaining_bytes,
1667                                                  &packet_size,
1668                                                  mount_crypt_stat,
1669                                                  filename->filename,
1670                                                  filename->filename_size);
1671                if (rc) {
1672                        printk(KERN_ERR "%s: Error attempting to generate "
1673                               "tag 70 packet; rc = [%d]\n", __func__,
1674                               rc);
1675                        kfree(filename->encrypted_filename);
1676                        filename->encrypted_filename = NULL;
1677                        filename->encrypted_filename_size = 0;
1678                        goto out;
1679                }
1680                filename->encrypted_filename_size = packet_size;
1681        } else {
1682                printk(KERN_ERR "%s: No support for requested filename "
1683                       "encryption method in this release\n", __func__);
1684                rc = -EOPNOTSUPP;
1685                goto out;
1686        }
1687out:
1688        return rc;
1689}
1690
1691static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1692                                  const char *name, size_t name_size)
1693{
1694        int rc = 0;
1695
1696        (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1697        if (!(*copied_name)) {
1698                rc = -ENOMEM;
1699                goto out;
1700        }
1701        memcpy((void *)(*copied_name), (void *)name, name_size);
1702        (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1703                                                 * in printing out the
1704                                                 * string in debug
1705                                                 * messages */
1706        (*copied_name_size) = name_size;
1707out:
1708        return rc;
1709}
1710
1711/**
1712 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1713 * @key_tfm: Crypto context for key material, set by this function
1714 * @cipher_name: Name of the cipher
1715 * @key_size: Size of the key in bytes
1716 *
1717 * Returns zero on success. Any crypto_tfm structs allocated here
1718 * should be released by other functions, such as on a superblock put
1719 * event, regardless of whether this function succeeds for fails.
1720 */
1721static int
1722ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1723                            char *cipher_name, size_t *key_size)
1724{
1725        char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1726        char *full_alg_name = NULL;
1727        int rc;
1728
1729        *key_tfm = NULL;
1730        if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1731                rc = -EINVAL;
1732                printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1733                      "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1734                goto out;
1735        }
1736        rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1737                                                    "ecb");
1738        if (rc)
1739                goto out;
1740        *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1741        if (IS_ERR(*key_tfm)) {
1742                rc = PTR_ERR(*key_tfm);
1743                printk(KERN_ERR "Unable to allocate crypto cipher with name "
1744                       "[%s]; rc = [%d]\n", full_alg_name, rc);
1745                goto out;
1746        }
1747        crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1748        if (*key_size == 0) {
1749                struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1750
1751                *key_size = alg->max_keysize;
1752        }
1753        get_random_bytes(dummy_key, *key_size);
1754        rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1755        if (rc) {
1756                printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1757                       "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1758                       rc);
1759                rc = -EINVAL;
1760                goto out;
1761        }
1762out:
1763        kfree(full_alg_name);
1764        return rc;
1765}
1766
1767struct kmem_cache *ecryptfs_key_tfm_cache;
1768static struct list_head key_tfm_list;
1769struct mutex key_tfm_list_mutex;
1770
1771int __init ecryptfs_init_crypto(void)
1772{
1773        mutex_init(&key_tfm_list_mutex);
1774        INIT_LIST_HEAD(&key_tfm_list);
1775        return 0;
1776}
1777
1778/**
1779 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1780 *
1781 * Called only at module unload time
1782 */
1783int ecryptfs_destroy_crypto(void)
1784{
1785        struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1786
1787        mutex_lock(&key_tfm_list_mutex);
1788        list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1789                                 key_tfm_list) {
1790                list_del(&key_tfm->key_tfm_list);
1791                if (key_tfm->key_tfm)
1792                        crypto_free_blkcipher(key_tfm->key_tfm);
1793                kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1794        }
1795        mutex_unlock(&key_tfm_list_mutex);
1796        return 0;
1797}
1798
1799int
1800ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1801                         size_t key_size)
1802{
1803        struct ecryptfs_key_tfm *tmp_tfm;
1804        int rc = 0;
1805
1806        BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1807
1808        tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1809        if (key_tfm != NULL)
1810                (*key_tfm) = tmp_tfm;
1811        if (!tmp_tfm) {
1812                rc = -ENOMEM;
1813                printk(KERN_ERR "Error attempting to allocate from "
1814                       "ecryptfs_key_tfm_cache\n");
1815                goto out;
1816        }
1817        mutex_init(&tmp_tfm->key_tfm_mutex);
1818        strncpy(tmp_tfm->cipher_name, cipher_name,
1819                ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1820        tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1821        tmp_tfm->key_size = key_size;
1822        rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1823                                         tmp_tfm->cipher_name,
1824                                         &tmp_tfm->key_size);
1825        if (rc) {
1826                printk(KERN_ERR "Error attempting to initialize key TFM "
1827                       "cipher with name = [%s]; rc = [%d]\n",
1828                       tmp_tfm->cipher_name, rc);
1829                kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1830                if (key_tfm != NULL)
1831                        (*key_tfm) = NULL;
1832                goto out;
1833        }
1834        list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1835out:
1836        return rc;
1837}
1838
1839/**
1840 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1841 * @cipher_name: the name of the cipher to search for
1842 * @key_tfm: set to corresponding tfm if found
1843 *
1844 * Searches for cached key_tfm matching @cipher_name
1845 * Must be called with &key_tfm_list_mutex held
1846 * Returns 1 if found, with @key_tfm set
1847 * Returns 0 if not found, with @key_tfm set to NULL
1848 */
1849int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1850{
1851        struct ecryptfs_key_tfm *tmp_key_tfm;
1852
1853        BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1854
1855        list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1856                if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1857                        if (key_tfm)
1858                                (*key_tfm) = tmp_key_tfm;
1859                        return 1;
1860                }
1861        }
1862        if (key_tfm)
1863                (*key_tfm) = NULL;
1864        return 0;
1865}
1866
1867/**
1868 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1869 *
1870 * @tfm: set to cached tfm found, or new tfm created
1871 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1872 * @cipher_name: the name of the cipher to search for and/or add
1873 *
1874 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1875 * Searches for cached item first, and creates new if not found.
1876 * Returns 0 on success, non-zero if adding new cipher failed
1877 */
1878int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1879                                               struct mutex **tfm_mutex,
1880                                               char *cipher_name)
1881{
1882        struct ecryptfs_key_tfm *key_tfm;
1883        int rc = 0;
1884
1885        (*tfm) = NULL;
1886        (*tfm_mutex) = NULL;
1887
1888        mutex_lock(&key_tfm_list_mutex);
1889        if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1890                rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1891                if (rc) {
1892                        printk(KERN_ERR "Error adding new key_tfm to list; "
1893                                        "rc = [%d]\n", rc);
1894                        goto out;
1895                }
1896        }
1897        (*tfm) = key_tfm->key_tfm;
1898        (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1899out:
1900        mutex_unlock(&key_tfm_list_mutex);
1901        return rc;
1902}
1903
1904/* 64 characters forming a 6-bit target field */
1905static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1906                                                 "EFGHIJKLMNOPQRST"
1907                                                 "UVWXYZabcdefghij"
1908                                                 "klmnopqrstuvwxyz");
1909
1910/* We could either offset on every reverse map or just pad some 0x00's
1911 * at the front here */
1912static const unsigned char filename_rev_map[256] = {
1913        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1914        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1915        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1916        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1917        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1918        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1919        0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1920        0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1921        0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1922        0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1923        0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1924        0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1925        0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1926        0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1927        0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1928        0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1929};
1930
1931/**
1932 * ecryptfs_encode_for_filename
1933 * @dst: Destination location for encoded filename
1934 * @dst_size: Size of the encoded filename in bytes
1935 * @src: Source location for the filename to encode
1936 * @src_size: Size of the source in bytes
1937 */
1938void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1939                                  unsigned char *src, size_t src_size)
1940{
1941        size_t num_blocks;
1942        size_t block_num = 0;
1943        size_t dst_offset = 0;
1944        unsigned char last_block[3];
1945
1946        if (src_size == 0) {
1947                (*dst_size) = 0;
1948                goto out;
1949        }
1950        num_blocks = (src_size / 3);
1951        if ((src_size % 3) == 0) {
1952                memcpy(last_block, (&src[src_size - 3]), 3);
1953        } else {
1954                num_blocks++;
1955                last_block[2] = 0x00;
1956                switch (src_size % 3) {
1957                case 1:
1958                        last_block[0] = src[src_size - 1];
1959                        last_block[1] = 0x00;
1960                        break;
1961                case 2:
1962                        last_block[0] = src[src_size - 2];
1963                        last_block[1] = src[src_size - 1];
1964                }
1965        }
1966        (*dst_size) = (num_blocks * 4);
1967        if (!dst)
1968                goto out;
1969        while (block_num < num_blocks) {
1970                unsigned char *src_block;
1971                unsigned char dst_block[4];
1972
1973                if (block_num == (num_blocks - 1))
1974                        src_block = last_block;
1975                else
1976                        src_block = &src[block_num * 3];
1977                dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1978                dst_block[1] = (((src_block[0] << 4) & 0x30)
1979                                | ((src_block[1] >> 4) & 0x0F));
1980                dst_block[2] = (((src_block[1] << 2) & 0x3C)
1981                                | ((src_block[2] >> 6) & 0x03));
1982                dst_block[3] = (src_block[2] & 0x3F);
1983                dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1984                dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1985                dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1986                dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1987                block_num++;
1988        }
1989out:
1990        return;
1991}
1992
1993static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1994{
1995        /* Not exact; conservatively long. Every block of 4
1996         * encoded characters decodes into a block of 3
1997         * decoded characters. This segment of code provides
1998         * the caller with the maximum amount of allocated
1999         * space that @dst will need to point to in a
2000         * subsequent call. */
2001        return ((encoded_size + 1) * 3) / 4;
2002}
2003
2004/**
2005 * ecryptfs_decode_from_filename
2006 * @dst: If NULL, this function only sets @dst_size and returns. If
2007 *       non-NULL, this function decodes the encoded octets in @src
2008 *       into the memory that @dst points to.
2009 * @dst_size: Set to the size of the decoded string.
2010 * @src: The encoded set of octets to decode.
2011 * @src_size: The size of the encoded set of octets to decode.
2012 */
2013static void
2014ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2015                              const unsigned char *src, size_t src_size)
2016{
2017        u8 current_bit_offset = 0;
2018        size_t src_byte_offset = 0;
2019        size_t dst_byte_offset = 0;
2020
2021        if (dst == NULL) {
2022                (*dst_size) = ecryptfs_max_decoded_size(src_size);
2023                goto out;
2024        }
2025        while (src_byte_offset < src_size) {
2026                unsigned char src_byte =
2027                                filename_rev_map[(int)src[src_byte_offset]];
2028
2029                switch (current_bit_offset) {
2030                case 0:
2031                        dst[dst_byte_offset] = (src_byte << 2);
2032                        current_bit_offset = 6;
2033                        break;
2034                case 6:
2035                        dst[dst_byte_offset++] |= (src_byte >> 4);
2036                        dst[dst_byte_offset] = ((src_byte & 0xF)
2037                                                 << 4);
2038                        current_bit_offset = 4;
2039                        break;
2040                case 4:
2041                        dst[dst_byte_offset++] |= (src_byte >> 2);
2042                        dst[dst_byte_offset] = (src_byte << 6);
2043                        current_bit_offset = 2;
2044                        break;
2045                case 2:
2046                        dst[dst_byte_offset++] |= (src_byte);
2047                        dst[dst_byte_offset] = 0;
2048                        current_bit_offset = 0;
2049                        break;
2050                }
2051                src_byte_offset++;
2052        }
2053        (*dst_size) = dst_byte_offset;
2054out:
2055        return;
2056}
2057
2058/**
2059 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2060 * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2061 * @name: The plaintext name
2062 * @length: The length of the plaintext
2063 * @encoded_name: The encypted name
2064 *
2065 * Encrypts and encodes a filename into something that constitutes a
2066 * valid filename for a filesystem, with printable characters.
2067 *
2068 * We assume that we have a properly initialized crypto context,
2069 * pointed to by crypt_stat->tfm.
2070 *
2071 * Returns zero on success; non-zero on otherwise
2072 */
2073int ecryptfs_encrypt_and_encode_filename(
2074        char **encoded_name,
2075        size_t *encoded_name_size,
2076        struct ecryptfs_crypt_stat *crypt_stat,
2077        struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2078        const char *name, size_t name_size)
2079{
2080        size_t encoded_name_no_prefix_size;
2081        int rc = 0;
2082
2083        (*encoded_name) = NULL;
2084        (*encoded_name_size) = 0;
2085        if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2086            || (mount_crypt_stat && (mount_crypt_stat->flags
2087                                     & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2088                struct ecryptfs_filename *filename;
2089
2090                filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2091                if (!filename) {
2092                        printk(KERN_ERR "%s: Out of memory whilst attempting "
2093                               "to kzalloc [%zd] bytes\n", __func__,
2094                               sizeof(*filename));
2095                        rc = -ENOMEM;
2096                        goto out;
2097                }
2098                filename->filename = (char *)name;
2099                filename->filename_size = name_size;
2100                rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2101                                               mount_crypt_stat);
2102                if (rc) {
2103                        printk(KERN_ERR "%s: Error attempting to encrypt "
2104                               "filename; rc = [%d]\n", __func__, rc);
2105                        kfree(filename);
2106                        goto out;
2107                }
2108                ecryptfs_encode_for_filename(
2109                        NULL, &encoded_name_no_prefix_size,
2110                        filename->encrypted_filename,
2111                        filename->encrypted_filename_size);
2112                if ((crypt_stat && (crypt_stat->flags
2113                                    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2114                    || (mount_crypt_stat
2115                        && (mount_crypt_stat->flags
2116                            & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2117                        (*encoded_name_size) =
2118                                (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2119                                 + encoded_name_no_prefix_size);
2120                else
2121                        (*encoded_name_size) =
2122                                (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2123                                 + encoded_name_no_prefix_size);
2124                (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2125                if (!(*encoded_name)) {
2126                        printk(KERN_ERR "%s: Out of memory whilst attempting "
2127                               "to kzalloc [%zd] bytes\n", __func__,
2128                               (*encoded_name_size));
2129                        rc = -ENOMEM;
2130                        kfree(filename->encrypted_filename);
2131                        kfree(filename);
2132                        goto out;
2133                }
2134                if ((crypt_stat && (crypt_stat->flags
2135                                    & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2136                    || (mount_crypt_stat
2137                        && (mount_crypt_stat->flags
2138                            & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2139                        memcpy((*encoded_name),
2140                               ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2141                               ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2142                        ecryptfs_encode_for_filename(
2143                            ((*encoded_name)
2144                             + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2145                            &encoded_name_no_prefix_size,
2146                            filename->encrypted_filename,
2147                            filename->encrypted_filename_size);
2148                        (*encoded_name_size) =
2149                                (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2150                                 + encoded_name_no_prefix_size);
2151                        (*encoded_name)[(*encoded_name_size)] = '\0';
2152                } else {
2153                        rc = -EOPNOTSUPP;
2154                }
2155                if (rc) {
2156                        printk(KERN_ERR "%s: Error attempting to encode "
2157                               "encrypted filename; rc = [%d]\n", __func__,
2158                               rc);
2159                        kfree((*encoded_name));
2160                        (*encoded_name) = NULL;
2161                        (*encoded_name_size) = 0;
2162                }
2163                kfree(filename->encrypted_filename);
2164                kfree(filename);
2165        } else {
2166                rc = ecryptfs_copy_filename(encoded_name,
2167                                            encoded_name_size,
2168                                            name, name_size);
2169        }
2170out:
2171        return rc;
2172}
2173
2174/**
2175 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2176 * @plaintext_name: The plaintext name
2177 * @plaintext_name_size: The plaintext name size
2178 * @ecryptfs_dir_dentry: eCryptfs directory dentry
2179 * @name: The filename in cipher text
2180 * @name_size: The cipher text name size
2181 *
2182 * Decrypts and decodes the filename.
2183 *
2184 * Returns zero on error; non-zero otherwise
2185 */
2186int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2187                                         size_t *plaintext_name_size,
2188                                         struct dentry *ecryptfs_dir_dentry,
2189                                         const char *name, size_t name_size)
2190{
2191        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2192                &ecryptfs_superblock_to_private(
2193                        ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2194        char *decoded_name;
2195        size_t decoded_name_size;
2196        size_t packet_size;
2197        int rc = 0;
2198
2199        if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2200            && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2201            && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2202            && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2203                        ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2204                const char *orig_name = name;
2205                size_t orig_name_size = name_size;
2206
2207                name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2208                name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2209                ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2210                                              name, name_size);
2211                decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2212                if (!decoded_name) {
2213                        printk(KERN_ERR "%s: Out of memory whilst attempting "
2214                               "to kmalloc [%zd] bytes\n", __func__,
2215                               decoded_name_size);
2216                        rc = -ENOMEM;
2217                        goto out;
2218                }
2219                ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2220                                              name, name_size);
2221                rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2222                                                  plaintext_name_size,
2223                                                  &packet_size,
2224                                                  mount_crypt_stat,
2225                                                  decoded_name,
2226                                                  decoded_name_size);
2227                if (rc) {
2228                        printk(KERN_INFO "%s: Could not parse tag 70 packet "
2229                               "from filename; copying through filename "
2230                               "as-is\n", __func__);
2231                        rc = ecryptfs_copy_filename(plaintext_name,
2232                                                    plaintext_name_size,
2233                                                    orig_name, orig_name_size);
2234                        goto out_free;
2235                }
2236        } else {
2237                rc = ecryptfs_copy_filename(plaintext_name,
2238                                            plaintext_name_size,
2239                                            name, name_size);
2240                goto out;
2241        }
2242out_free:
2243        kfree(decoded_name);
2244out:
2245        return rc;
2246}
2247
2248#define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2249
2250int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2251                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2252{
2253        struct blkcipher_desc desc;
2254        struct mutex *tfm_mutex;
2255        size_t cipher_blocksize;
2256        int rc;
2257
2258        if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2259                (*namelen) = lower_namelen;
2260                return 0;
2261        }
2262
2263        rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2264                        mount_crypt_stat->global_default_fn_cipher_name);
2265        if (unlikely(rc)) {
2266                (*namelen) = 0;
2267                return rc;
2268        }
2269
2270        mutex_lock(tfm_mutex);
2271        cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2272        mutex_unlock(tfm_mutex);
2273
2274        /* Return an exact amount for the common cases */
2275        if (lower_namelen == NAME_MAX
2276            && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2277                (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2278                return 0;
2279        }
2280
2281        /* Return a safe estimate for the uncommon cases */
2282        (*namelen) = lower_namelen;
2283        (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2284        /* Since this is the max decoded size, subtract 1 "decoded block" len */
2285        (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2286        (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2287        (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2288        /* Worst case is that the filename is padded nearly a full block size */
2289        (*namelen) -= cipher_blocksize - 1;
2290
2291        if ((*namelen) < 0)
2292                (*namelen) = 0;
2293
2294        return 0;
2295}
2296
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