fs/ecryptfs/crypto.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  *
   4  * Copyright (C) 1997-2004 Erez Zadok
   5  * Copyright (C) 2001-2004 Stony Brook University
   6  * Copyright (C) 2004-2007 International Business Machines Corp.
   7  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   8  *              Michael C. Thompson <mcthomps@us.ibm.com>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of the
  13  * License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  23  * 02111-1307, USA.
  24  */
  25
  26 #include <linux/fs.h>
  27 #include <linux/mount.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/random.h>
  30 #include <linux/compiler.h>
  31 #include <linux/key.h>
  32 #include <linux/namei.h>
  33 #include <linux/crypto.h>
  34 #include <linux/file.h>
  35 #include <linux/scatterlist.h>
  36 #include <linux/slab.h>
  37 #include <asm/unaligned.h>
  38 #include "ecryptfs_kernel.h"
  39
  40 static int
  41 ecryptfs_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);
  45 static int
  46 ecryptfs_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  */
  58 void 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  */
  73 void 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  */
  95 static 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         }
 141 out:
 142         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
 143         return rc;
 144 }
 145
 146 static 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;
 164 out:
 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  */
 179 int 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         }
 213 out:
 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  */
 223 void
 224 ecryptfs_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  */
 241 void 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
 257 void 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  */
 291 int 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  */
 335 static 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);
 372 out:
 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  */
 381 static 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  */
 401 static 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         if (unlikely(ecryptfs_verbosity > 0)) {
 421                 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
 422                                 "with iv:\n");
 423                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
 424                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
 425                                 "encryption:\n");
 426                 ecryptfs_dump_hex((char *)
 427                                   (page_address(page)
 428                                    + (extent_offset * crypt_stat->extent_size)),
 429                                   8);
 430         }
 431         rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
 432                                           page, (extent_offset
 433                                                  * crypt_stat->extent_size),
 434                                           crypt_stat->extent_size, extent_iv);
 435         if (rc < 0) {
 436                 printk(KERN_ERR "%s: Error attempting to encrypt page with "
 437                        "page->index = [%ld], extent_offset = [%ld]; "
 438                        "rc = [%d]\n", __func__, page->index, extent_offset,
 439                        rc);
 440                 goto out;
 441         }
 442         rc = 0;
 443         if (unlikely(ecryptfs_verbosity > 0)) {
 444                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16llx]; "
 445                         "rc = [%d]\n",
 446                         (unsigned long long)(extent_base + extent_offset), rc);
 447                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 448                                 "encryption:\n");
 449                 ecryptfs_dump_hex((char *)(page_address(enc_extent_page)), 8);
 450         }
 451 out:
 452         return rc;
 453 }
 454
 455 /**
 456  * ecryptfs_encrypt_page
 457  * @page: Page mapped from the eCryptfs inode for the file; contains
 458  *        decrypted content that needs to be encrypted (to a temporary
 459  *        page; not in place) and written out to the lower file
 460  *
 461  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 462  * that eCryptfs pages may straddle the lower pages -- for instance,
 463  * if the file was created on a machine with an 8K page size
 464  * (resulting in an 8K header), and then the file is copied onto a
 465  * host with a 32K page size, then when reading page 0 of the eCryptfs
 466  * file, 24K of page 0 of the lower file will be read and decrypted,
 467  * and then 8K of page 1 of the lower file will be read and decrypted.
 468  *
 469  * Returns zero on success; negative on error
 470  */
 471 int ecryptfs_encrypt_page(struct page *page)
 472 {
 473         struct inode *ecryptfs_inode;
 474         struct ecryptfs_crypt_stat *crypt_stat;
 475         char *enc_extent_virt;
 476         struct page *enc_extent_page = NULL;
 477         loff_t extent_offset;
 478         int rc = 0;
 479
 480         ecryptfs_inode = page->mapping->host;
 481         crypt_stat =
 482                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 483         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 484         enc_extent_page = alloc_page(GFP_USER);
 485         if (!enc_extent_page) {
 486                 rc = -ENOMEM;
 487                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 488                                 "encrypted extent\n");
 489                 goto out;
 490         }
 491         enc_extent_virt = kmap(enc_extent_page);
 492         for (extent_offset = 0;
 493              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 494              extent_offset++) {
 495                 loff_t offset;
 496
 497                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
 498                                              extent_offset);
 499                 if (rc) {
 500                         printk(KERN_ERR "%s: Error encrypting extent; "
 501                                "rc = [%d]\n", __func__, rc);
 502                         goto out;
 503                 }
 504                 ecryptfs_lower_offset_for_extent(
 505                         &offset, ((((loff_t)page->index)
 506                                    * (PAGE_CACHE_SIZE
 507                                       / crypt_stat->extent_size))
 508                                   + extent_offset), crypt_stat);
 509                 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
 510                                           offset, crypt_stat->extent_size);
 511                 if (rc < 0) {
 512                         ecryptfs_printk(KERN_ERR, "Error attempting "
 513                                         "to write lower page; rc = [%d]"
 514                                         "\n", rc);
 515                         goto out;
 516                 }
 517         }
 518         rc = 0;
 519 out:
 520         if (enc_extent_page) {
 521                 kunmap(enc_extent_page);
 522                 __free_page(enc_extent_page);
 523         }
 524         return rc;
 525 }
 526
 527 static int ecryptfs_decrypt_extent(struct page *page,
 528                                    struct ecryptfs_crypt_stat *crypt_stat,
 529                                    struct page *enc_extent_page,
 530                                    unsigned long extent_offset)
 531 {
 532         loff_t extent_base;
 533         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 534         int rc;
 535
 536         extent_base = (((loff_t)page->index)
 537                        * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
 538         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 539                                 (extent_base + extent_offset));
 540         if (rc) {
 541                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 542                         "extent [0x%.16llx]; rc = [%d]\n",
 543                         (unsigned long long)(extent_base + extent_offset), rc);
 544                 goto out;
 545         }
 546         if (unlikely(ecryptfs_verbosity > 0)) {
 547                 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
 548                                 "with iv:\n");
 549                 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
 550                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
 551                                 "decryption:\n");
 552                 ecryptfs_dump_hex((char *)
 553                                   (page_address(enc_extent_page)
 554                                    + (extent_offset * crypt_stat->extent_size)),
 555                                   8);
 556         }
 557         rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
 558                                           (extent_offset
 559                                            * crypt_stat->extent_size),
 560                                           enc_extent_page, 0,
 561                                           crypt_stat->extent_size, extent_iv);
 562         if (rc < 0) {
 563                 printk(KERN_ERR "%s: Error attempting to decrypt to page with "
 564                        "page->index = [%ld], extent_offset = [%ld]; "
 565                        "rc = [%d]\n", __func__, page->index, extent_offset,
 566                        rc);
 567                 goto out;
 568         }
 569         rc = 0;
 570         if (unlikely(ecryptfs_verbosity > 0)) {
 571                 ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16llx]; "
 572                         "rc = [%d]\n",
 573                         (unsigned long long)(extent_base + extent_offset), rc);
 574                 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 575                                 "decryption:\n");
 576                 ecryptfs_dump_hex((char *)(page_address(page)
 577                                            + (extent_offset
 578                                               * crypt_stat->extent_size)), 8);
 579         }
 580 out:
 581         return rc;
 582 }
 583
 584 /**
 585  * ecryptfs_decrypt_page
 586  * @page: Page mapped from the eCryptfs inode for the file; data read
 587  *        and decrypted from the lower file will be written into this
 588  *        page
 589  *
 590  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 591  * that eCryptfs pages may straddle the lower pages -- for instance,
 592  * if the file was created on a machine with an 8K page size
 593  * (resulting in an 8K header), and then the file is copied onto a
 594  * host with a 32K page size, then when reading page 0 of the eCryptfs
 595  * file, 24K of page 0 of the lower file will be read and decrypted,
 596  * and then 8K of page 1 of the lower file will be read and decrypted.
 597  *
 598  * Returns zero on success; negative on error
 599  */
 600 int ecryptfs_decrypt_page(struct page *page)
 601 {
 602         struct inode *ecryptfs_inode;
 603         struct ecryptfs_crypt_stat *crypt_stat;
 604         char *enc_extent_virt;
 605         struct page *enc_extent_page = NULL;
 606         unsigned long extent_offset;
 607         int rc = 0;
 608
 609         ecryptfs_inode = page->mapping->host;
 610         crypt_stat =
 611                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 612         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 613         enc_extent_page = alloc_page(GFP_USER);
 614         if (!enc_extent_page) {
 615                 rc = -ENOMEM;
 616                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 617                                 "encrypted extent\n");
 618                 goto out;
 619         }
 620         enc_extent_virt = kmap(enc_extent_page);
 621         for (extent_offset = 0;
 622              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 623              extent_offset++) {
 624                 loff_t offset;
 625
 626                 ecryptfs_lower_offset_for_extent(
 627                         &offset, ((page->index * (PAGE_CACHE_SIZE
 628                                                   / crypt_stat->extent_size))
 629                                   + extent_offset), crypt_stat);
 630                 rc = ecryptfs_read_lower(enc_extent_virt, offset,
 631                                          crypt_stat->extent_size,
 632                                          ecryptfs_inode);
 633                 if (rc < 0) {
 634                         ecryptfs_printk(KERN_ERR, "Error attempting "
 635                                         "to read lower page; rc = [%d]"
 636                                         "\n", rc);
 637                         goto out;
 638                 }
 639                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
 640                                              extent_offset);
 641                 if (rc) {
 642                         printk(KERN_ERR "%s: Error encrypting extent; "
 643                                "rc = [%d]\n", __func__, rc);
 644                         goto out;
 645                 }
 646         }
 647 out:
 648         if (enc_extent_page) {
 649                 kunmap(enc_extent_page);
 650                 __free_page(enc_extent_page);
 651         }
 652         return rc;
 653 }
 654
 655 /**
 656  * decrypt_scatterlist
 657  * @crypt_stat: Cryptographic context
 658  * @dest_sg: The destination scatterlist to decrypt into
 659  * @src_sg: The source scatterlist to decrypt from
 660  * @size: The number of bytes to decrypt
 661  * @iv: The initialization vector to use for the decryption
 662  *
 663  * Returns the number of bytes decrypted; negative value on error
 664  */
 665 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 666                                struct scatterlist *dest_sg,
 667                                struct scatterlist *src_sg, int size,
 668                                unsigned char *iv)
 669 {
 670         struct blkcipher_desc desc = {
 671                 .tfm = crypt_stat->tfm,
 672                 .info = iv,
 673                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 674         };
 675         int rc = 0;
 676
 677         /* Consider doing this once, when the file is opened */
 678         mutex_lock(&crypt_stat->cs_tfm_mutex);
 679         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 680                                      crypt_stat->key_size);
 681         if (rc) {
 682                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 683                                 rc);
 684                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 685                 rc = -EINVAL;
 686                 goto out;
 687         }
 688         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
 689         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
 690         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 691         if (rc) {
 692                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
 693                                 rc);
 694                 goto out;
 695         }
 696         rc = size;
 697 out:
 698         return rc;
 699 }
 700
 701 /**
 702  * ecryptfs_encrypt_page_offset
 703  * @crypt_stat: The cryptographic context
 704  * @dst_page: The page to encrypt into
 705  * @dst_offset: The offset in the page to encrypt into
 706  * @src_page: The page to encrypt from
 707  * @src_offset: The offset in the page to encrypt from
 708  * @size: The number of bytes to encrypt
 709  * @iv: The initialization vector to use for the encryption
 710  *
 711  * Returns the number of bytes encrypted
 712  */
 713 static int
 714 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 715                              struct page *dst_page, int dst_offset,
 716                              struct page *src_page, int src_offset, int size,
 717                              unsigned char *iv)
 718 {
 719         struct scatterlist src_sg, dst_sg;
 720
 721         sg_init_table(&src_sg, 1);
 722         sg_init_table(&dst_sg, 1);
 723
 724         sg_set_page(&src_sg, src_page, size, src_offset);
 725         sg_set_page(&dst_sg, dst_page, size, dst_offset);
 726         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 727 }
 728
 729 /**
 730  * ecryptfs_decrypt_page_offset
 731  * @crypt_stat: The cryptographic context
 732  * @dst_page: The page to decrypt into
 733  * @dst_offset: The offset in the page to decrypt into
 734  * @src_page: The page to decrypt from
 735  * @src_offset: The offset in the page to decrypt from
 736  * @size: The number of bytes to decrypt
 737  * @iv: The initialization vector to use for the decryption
 738  *
 739  * Returns the number of bytes decrypted
 740  */
 741 static int
 742 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 743                              struct page *dst_page, int dst_offset,
 744                              struct page *src_page, int src_offset, int size,
 745                              unsigned char *iv)
 746 {
 747         struct scatterlist src_sg, dst_sg;
 748
 749         sg_init_table(&src_sg, 1);
 750         sg_set_page(&src_sg, src_page, size, src_offset);
 751
 752         sg_init_table(&dst_sg, 1);
 753         sg_set_page(&dst_sg, dst_page, size, dst_offset);
 754
 755         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 756 }
 757
 758 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 759
 760 /**
 761  * ecryptfs_init_crypt_ctx
 762  * @crypt_stat: Uninitialized crypt stats structure
 763  *
 764  * Initialize the crypto context.
 765  *
 766  * TODO: Performance: Keep a cache of initialized cipher contexts;
 767  * only init if needed
 768  */
 769 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 770 {
 771         char *full_alg_name;
 772         int rc = -EINVAL;
 773
 774         if (!crypt_stat->cipher) {
 775                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
 776                 goto out;
 777         }
 778         ecryptfs_printk(KERN_DEBUG,
 779                         "Initializing cipher [%s]; strlen = [%d]; "
 780                         "key_size_bits = [%zd]\n",
 781                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 782                         crypt_stat->key_size << 3);
 783         if (crypt_stat->tfm) {
 784                 rc = 0;
 785                 goto out;
 786         }
 787         mutex_lock(&crypt_stat->cs_tfm_mutex);
 788         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 789                                                     crypt_stat->cipher, "cbc");
 790         if (rc)
 791                 goto out_unlock;
 792         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
 793                                                  CRYPTO_ALG_ASYNC);
 794         kfree(full_alg_name);
 795         if (IS_ERR(crypt_stat->tfm)) {
 796                 rc = PTR_ERR(crypt_stat->tfm);
 797                 crypt_stat->tfm = NULL;
 798                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 799                                 "Error initializing cipher [%s]\n",
 800                                 crypt_stat->cipher);
 801                 goto out_unlock;
 802         }
 803         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 804         rc = 0;
 805 out_unlock:
 806         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 807 out:
 808         return rc;
 809 }
 810
 811 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 812 {
 813         int extent_size_tmp;
 814
 815         crypt_stat->extent_mask = 0xFFFFFFFF;
 816         crypt_stat->extent_shift = 0;
 817         if (crypt_stat->extent_size == 0)
 818                 return;
 819         extent_size_tmp = crypt_stat->extent_size;
 820         while ((extent_size_tmp & 0x01) == 0) {
 821                 extent_size_tmp >>= 1;
 822                 crypt_stat->extent_mask <<= 1;
 823                 crypt_stat->extent_shift++;
 824         }
 825 }
 826
 827 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 828 {
 829         /* Default values; may be overwritten as we are parsing the
 830          * packets. */
 831         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 832         set_extent_mask_and_shift(crypt_stat);
 833         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 834         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 835                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 836         else {
 837                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 838                         crypt_stat->metadata_size =
 839                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 840                 else
 841                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
 842         }
 843 }
 844
 845 /**
 846  * ecryptfs_compute_root_iv
 847  * @crypt_stats
 848  *
 849  * On error, sets the root IV to all 0's.
 850  */
 851 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 852 {
 853         int rc = 0;
 854         char dst[MD5_DIGEST_SIZE];
 855
 856         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 857         BUG_ON(crypt_stat->iv_bytes <= 0);
 858         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 859                 rc = -EINVAL;
 860                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 861                                 "cannot generate root IV\n");
 862                 goto out;
 863         }
 864         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 865                                     crypt_stat->key_size);
 866         if (rc) {
 867                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 868                                 "MD5 while generating root IV\n");
 869                 goto out;
 870         }
 871         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 872 out:
 873         if (rc) {
 874                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 875                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 876         }
 877         return rc;
 878 }
 879
 880 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 881 {
 882         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 883         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 884         ecryptfs_compute_root_iv(crypt_stat);
 885         if (unlikely(ecryptfs_verbosity > 0)) {
 886                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 887                 ecryptfs_dump_hex(crypt_stat->key,
 888                                   crypt_stat->key_size);
 889         }
 890 }
 891
 892 /**
 893  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 894  * @crypt_stat: The inode's cryptographic context
 895  * @mount_crypt_stat: The mount point's cryptographic context
 896  *
 897  * This function propagates the mount-wide flags to individual inode
 898  * flags.
 899  */
 900 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 901         struct ecryptfs_crypt_stat *crypt_stat,
 902         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 903 {
 904         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 905                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 906         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 907                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 908         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 909                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 910                 if (mount_crypt_stat->flags
 911                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 912                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 913                 else if (mount_crypt_stat->flags
 914                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 915                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 916         }
 917 }
 918
 919 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 920         struct ecryptfs_crypt_stat *crypt_stat,
 921         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 922 {
 923         struct ecryptfs_global_auth_tok *global_auth_tok;
 924         int rc = 0;
 925
 926         mutex_lock(&crypt_stat->keysig_list_mutex);
 927         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 928
 929         list_for_each_entry(global_auth_tok,
 930                             &mount_crypt_stat->global_auth_tok_list,
 931                             mount_crypt_stat_list) {
 932                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 933                         continue;
 934                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 935                 if (rc) {
 936                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 937                         goto out;
 938                 }
 939         }
 940
 941 out:
 942         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 943         mutex_unlock(&crypt_stat->keysig_list_mutex);
 944         return rc;
 945 }
 946
 947 /**
 948  * ecryptfs_set_default_crypt_stat_vals
 949  * @crypt_stat: The inode's cryptographic context
 950  * @mount_crypt_stat: The mount point's cryptographic context
 951  *
 952  * Default values in the event that policy does not override them.
 953  */
 954 static void ecryptfs_set_default_crypt_stat_vals(
 955         struct ecryptfs_crypt_stat *crypt_stat,
 956         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 957 {
 958         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 959                                                       mount_crypt_stat);
 960         ecryptfs_set_default_sizes(crypt_stat);
 961         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 962         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 963         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 964         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 965         crypt_stat->mount_crypt_stat = mount_crypt_stat;
 966 }
 967
 968 /**
 969  * ecryptfs_new_file_context
 970  * @ecryptfs_inode: The eCryptfs inode
 971  *
 972  * If the crypto context for the file has not yet been established,
 973  * this is where we do that.  Establishing a new crypto context
 974  * involves the following decisions:
 975  *  - What cipher to use?
 976  *  - What set of authentication tokens to use?
 977  * Here we just worry about getting enough information into the
 978  * authentication tokens so that we know that they are available.
 979  * We associate the available authentication tokens with the new file
 980  * via the set of signatures in the crypt_stat struct.  Later, when
 981  * the headers are actually written out, we may again defer to
 982  * userspace to perform the encryption of the session key; for the
 983  * foreseeable future, this will be the case with public key packets.
 984  *
 985  * Returns zero on success; non-zero otherwise
 986  */
 987 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 988 {
 989         struct ecryptfs_crypt_stat *crypt_stat =
 990             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 991         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 992             &ecryptfs_superblock_to_private(
 993                     ecryptfs_inode->i_sb)->mount_crypt_stat;
 994         int cipher_name_len;
 995         int rc = 0;
 996
 997         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 998         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 999         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1000                                                       mount_crypt_stat);
1001         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1002                                                          mount_crypt_stat);
1003         if (rc) {
1004                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1005                        "to the inode key sigs; rc = [%d]\n", rc);
1006                 goto out;
1007         }
1008         cipher_name_len =
1009                 strlen(mount_crypt_stat->global_default_cipher_name);
1010         memcpy(crypt_stat->cipher,
1011                mount_crypt_stat->global_default_cipher_name,
1012                cipher_name_len);
1013         crypt_stat->cipher[cipher_name_len] = '\0';
1014         crypt_stat->key_size =
1015                 mount_crypt_stat->global_default_cipher_key_size;
1016         ecryptfs_generate_new_key(crypt_stat);
1017         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1018         if (rc)
1019                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1020                                 "context for cipher [%s]: rc = [%d]\n",
1021                                 crypt_stat->cipher, rc);
1022 out:
1023         return rc;
1024 }
1025
1026 /**
1027  * ecryptfs_validate_marker - check for the ecryptfs marker
1028  * @data: The data block in which to check
1029  *
1030  * Returns zero if marker found; -EINVAL if not found
1031  */
1032 static int ecryptfs_validate_marker(char *data)
1033 {
1034         u32 m_1, m_2;
1035
1036         m_1 = get_unaligned_be32(data);
1037         m_2 = get_unaligned_be32(data + 4);
1038         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1039                 return 0;
1040         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1041                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1042                         MAGIC_ECRYPTFS_MARKER);
1043         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1044                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1045         return -EINVAL;
1046 }
1047
1048 struct ecryptfs_flag_map_elem {
1049         u32 file_flag;
1050         u32 local_flag;
1051 };
1052
1053 /* Add support for additional flags by adding elements here. */
1054 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1055         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1056         {0x00000002, ECRYPTFS_ENCRYPTED},
1057         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
1058         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
1059 };
1060
1061 /**
1062  * ecryptfs_process_flags
1063  * @crypt_stat: The cryptographic context
1064  * @page_virt: Source data to be parsed
1065  * @bytes_read: Updated with the number of bytes read
1066  *
1067  * Returns zero on success; non-zero if the flag set is invalid
1068  */
1069 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1070                                   char *page_virt, int *bytes_read)
1071 {
1072         int rc = 0;
1073         int i;
1074         u32 flags;
1075
1076         flags = get_unaligned_be32(page_virt);
1077         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1078                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1079                 if (flags & ecryptfs_flag_map[i].file_flag) {
1080                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1081                 } else
1082                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1083         /* Version is in top 8 bits of the 32-bit flag vector */
1084         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1085         (*bytes_read) = 4;
1086         return rc;
1087 }
1088
1089 /**
1090  * write_ecryptfs_marker
1091  * @page_virt: The pointer to in a page to begin writing the marker
1092  * @written: Number of bytes written
1093  *
1094  * Marker = 0x3c81b7f5
1095  */
1096 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1097 {
1098         u32 m_1, m_2;
1099
1100         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1101         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1102         put_unaligned_be32(m_1, page_virt);
1103         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
1104         put_unaligned_be32(m_2, page_virt);
1105         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1106 }
1107
1108 void ecryptfs_write_crypt_stat_flags(char *page_virt,
1109                                      struct ecryptfs_crypt_stat *crypt_stat,
1110                                      size_t *written)
1111 {
1112         u32 flags = 0;
1113         int i;
1114
1115         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1116                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1117                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1118                         flags |= ecryptfs_flag_map[i].file_flag;
1119         /* Version is in top 8 bits of the 32-bit flag vector */
1120         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1121         put_unaligned_be32(flags, page_virt);
1122         (*written) = 4;
1123 }
1124
1125 struct ecryptfs_cipher_code_str_map_elem {
1126         char cipher_str[16];
1127         u8 cipher_code;
1128 };
1129
1130 /* Add support for additional ciphers by adding elements here. The
1131  * cipher_code is whatever OpenPGP applicatoins use to identify the
1132  * ciphers. List in order of probability. */
1133 static struct ecryptfs_cipher_code_str_map_elem
1134 ecryptfs_cipher_code_str_map[] = {
1135         {"aes",RFC2440_CIPHER_AES_128 },
1136         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1137         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1138         {"cast5", RFC2440_CIPHER_CAST_5},
1139         {"twofish", RFC2440_CIPHER_TWOFISH},
1140         {"cast6", RFC2440_CIPHER_CAST_6},
1141         {"aes", RFC2440_CIPHER_AES_192},
1142         {"aes", RFC2440_CIPHER_AES_256}
1143 };
1144
1145 /**
1146  * ecryptfs_code_for_cipher_string
1147  * @cipher_name: The string alias for the cipher
1148  * @key_bytes: Length of key in bytes; used for AES code selection
1149  *
1150  * Returns zero on no match, or the cipher code on match
1151  */
1152 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
1153 {
1154         int i;
1155         u8 code = 0;
1156         struct ecryptfs_cipher_code_str_map_elem *map =
1157                 ecryptfs_cipher_code_str_map;
1158
1159         if (strcmp(cipher_name, "aes") == 0) {
1160                 switch (key_bytes) {
1161                 case 16:
1162                         code = RFC2440_CIPHER_AES_128;
1163                         break;
1164                 case 24:
1165                         code = RFC2440_CIPHER_AES_192;
1166                         break;
1167                 case 32:
1168                         code = RFC2440_CIPHER_AES_256;
1169                 }
1170         } else {
1171                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1172                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1173                                 code = map[i].cipher_code;
1174                                 break;
1175                         }
1176         }
1177         return code;
1178 }
1179
1180 /**
1181  * ecryptfs_cipher_code_to_string
1182  * @str: Destination to write out the cipher name
1183  * @cipher_code: The code to convert to cipher name string
1184  *
1185  * Returns zero on success
1186  */
1187 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1188 {
1189         int rc = 0;
1190         int i;
1191
1192         str[0] = '\0';
1193         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1194                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1195                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1196         if (str[0] == '\0') {
1197                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1198                                 "[%d]\n", cipher_code);
1199                 rc = -EINVAL;
1200         }
1201         return rc;
1202 }
1203
1204 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1205 {
1206         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1207         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1208         int rc;
1209
1210         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1211                                  inode);
1212         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1213                 return rc >= 0 ? -EINVAL : rc;
1214         rc = ecryptfs_validate_marker(marker);
1215         if (!rc)
1216                 ecryptfs_i_size_init(file_size, inode);
1217         return rc;
1218 }
1219
1220 void
1221 ecryptfs_write_header_metadata(char *virt,
1222                                struct ecryptfs_crypt_stat *crypt_stat,
1223                                size_t *written)
1224 {
1225         u32 header_extent_size;
1226         u16 num_header_extents_at_front;
1227
1228         header_extent_size = (u32)crypt_stat->extent_size;
1229         num_header_extents_at_front =
1230                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1231         put_unaligned_be32(header_extent_size, virt);
1232         virt += 4;
1233         put_unaligned_be16(num_header_extents_at_front, virt);
1234         (*written) = 6;
1235 }
1236
1237 struct kmem_cache *ecryptfs_header_cache;
1238
1239 /**
1240  * ecryptfs_write_headers_virt
1241  * @page_virt: The virtual address to write the headers to
1242  * @max: The size of memory allocated at page_virt
1243  * @size: Set to the number of bytes written by this function
1244  * @crypt_stat: The cryptographic context
1245  * @ecryptfs_dentry: The eCryptfs dentry
1246  *
1247  * Format version: 1
1248  *
1249  *   Header Extent:
1250  *     Octets 0-7:        Unencrypted file size (big-endian)
1251  *     Octets 8-15:       eCryptfs special marker
1252  *     Octets 16-19:      Flags
1253  *      Octet 16:         File format version number (between 0 and 255)
1254  *      Octets 17-18:     Reserved
1255  *      Octet 19:         Bit 1 (lsb): Reserved
1256  *                        Bit 2: Encrypted?
1257  *                        Bits 3-8: Reserved
1258  *     Octets 20-23:      Header extent size (big-endian)
1259  *     Octets 24-25:      Number of header extents at front of file
1260  *                        (big-endian)
1261  *     Octet  26:         Begin RFC 2440 authentication token packet set
1262  *   Data Extent 0:
1263  *     Lower data (CBC encrypted)
1264  *   Data Extent 1:
1265  *     Lower data (CBC encrypted)
1266  *   ...
1267  *
1268  * Returns zero on success
1269  */
1270 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1271                                        size_t *size,
1272                                        struct ecryptfs_crypt_stat *crypt_stat,
1273                                        struct dentry *ecryptfs_dentry)
1274 {
1275         int rc;
1276         size_t written;
1277         size_t offset;
1278
1279         offset = ECRYPTFS_FILE_SIZE_BYTES;
1280         write_ecryptfs_marker((page_virt + offset), &written);
1281         offset += written;
1282         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1283                                         &written);
1284         offset += written;
1285         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1286                                        &written);
1287         offset += written;
1288         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1289                                               ecryptfs_dentry, &written,
1290                                               max - offset);
1291         if (rc)
1292                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1293                                 "set; rc = [%d]\n", rc);
1294         if (size) {
1295                 offset += written;
1296                 *size = offset;
1297         }
1298         return rc;
1299 }
1300
1301 static int
1302 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1303                                     char *virt, size_t virt_len)
1304 {
1305         int rc;
1306
1307         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1308                                   0, virt_len);
1309         if (rc < 0)
1310                 printk(KERN_ERR "%s: Error attempting to write header "
1311                        "information to lower file; rc = [%d]\n", __func__, rc);
1312         else
1313                 rc = 0;
1314         return rc;
1315 }
1316
1317 static int
1318 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1319                                  char *page_virt, size_t size)
1320 {
1321         int rc;
1322
1323         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1324                                size, 0);
1325         return rc;
1326 }
1327
1328 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1329                                                unsigned int order)
1330 {
1331         struct page *page;
1332
1333         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1334         if (page)
1335                 return (unsigned long) page_address(page);
1336         return 0;
1337 }
1338
1339 /**
1340  * ecryptfs_write_metadata
1341  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1342  * @ecryptfs_inode: The newly created eCryptfs inode
1343  *
1344  * Write the file headers out.  This will likely involve a userspace
1345  * callout, in which the session key is encrypted with one or more
1346  * public keys and/or the passphrase necessary to do the encryption is
1347  * retrieved via a prompt.  Exactly what happens at this point should
1348  * be policy-dependent.
1349  *
1350  * Returns zero on success; non-zero on error
1351  */
1352 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1353                             struct inode *ecryptfs_inode)
1354 {
1355         struct ecryptfs_crypt_stat *crypt_stat =
1356                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1357         unsigned int order;
1358         char *virt;
1359         size_t virt_len;
1360         size_t size = 0;
1361         int rc = 0;
1362
1363         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1364                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1365                         printk(KERN_ERR "Key is invalid; bailing out\n");
1366                         rc = -EINVAL;
1367                         goto out;
1368                 }
1369         } else {
1370                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1371                        __func__);
1372                 rc = -EINVAL;
1373                 goto out;
1374         }
1375         virt_len = crypt_stat->metadata_size;
1376         order = get_order(virt_len);
1377         /* Released in this function */
1378         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1379         if (!virt) {
1380                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1381                 rc = -ENOMEM;
1382                 goto out;
1383         }
1384         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1385         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1386                                          ecryptfs_dentry);
1387         if (unlikely(rc)) {
1388                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1389                        __func__, rc);
1390                 goto out_free;
1391         }
1392         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1393                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1394                                                       size);
1395         else
1396                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1397                                                          virt_len);
1398         if (rc) {
1399                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1400                        "rc = [%d]\n", __func__, rc);
1401                 goto out_free;
1402         }
1403 out_free:
1404         free_pages((unsigned long)virt, order);
1405 out:
1406         return rc;
1407 }
1408
1409 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1410 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1411 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1412                                  char *virt, int *bytes_read,
1413                                  int validate_header_size)
1414 {
1415         int rc = 0;
1416         u32 header_extent_size;
1417         u16 num_header_extents_at_front;
1418
1419         header_extent_size = get_unaligned_be32(virt);
1420         virt += sizeof(__be32);
1421         num_header_extents_at_front = get_unaligned_be16(virt);
1422         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1423                                      * (size_t)header_extent_size));
1424         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1425         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1426             && (crypt_stat->metadata_size
1427                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1428                 rc = -EINVAL;
1429                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1430                        crypt_stat->metadata_size);
1431         }
1432         return rc;
1433 }
1434
1435 /**
1436  * set_default_header_data
1437  * @crypt_stat: The cryptographic context
1438  *
1439  * For version 0 file format; this function is only for backwards
1440  * compatibility for files created with the prior versions of
1441  * eCryptfs.
1442  */
1443 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1444 {
1445         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1446 }
1447
1448 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1449 {
1450         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1451         struct ecryptfs_crypt_stat *crypt_stat;
1452         u64 file_size;
1453
1454         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1455         mount_crypt_stat =
1456                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1457         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1458                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1459                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1460                         file_size += crypt_stat->metadata_size;
1461         } else
1462                 file_size = get_unaligned_be64(page_virt);
1463         i_size_write(inode, (loff_t)file_size);
1464         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1465 }
1466
1467 /**
1468  * ecryptfs_read_headers_virt
1469  * @page_virt: The virtual address into which to read the headers
1470  * @crypt_stat: The cryptographic context
1471  * @ecryptfs_dentry: The eCryptfs dentry
1472  * @validate_header_size: Whether to validate the header size while reading
1473  *
1474  * Read/parse the header data. The header format is detailed in the
1475  * comment block for the ecryptfs_write_headers_virt() function.
1476  *
1477  * Returns zero on success
1478  */
1479 static int ecryptfs_read_headers_virt(char *page_virt,
1480                                       struct ecryptfs_crypt_stat *crypt_stat,
1481                                       struct dentry *ecryptfs_dentry,
1482                                       int validate_header_size)
1483 {
1484         int rc = 0;
1485         int offset;
1486         int bytes_read;
1487
1488         ecryptfs_set_default_sizes(crypt_stat);
1489         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1490                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1491         offset = ECRYPTFS_FILE_SIZE_BYTES;
1492         rc = ecryptfs_validate_marker(page_virt + offset);
1493         if (rc)
1494                 goto out;
1495         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1496                 ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1497         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1498         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1499                                     &bytes_read);
1500         if (rc) {
1501                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1502                 goto out;
1503         }
1504         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1505                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1506                                 "file version [%d] is supported by this "
1507                                 "version of eCryptfs\n",
1508                                 crypt_stat->file_version,
1509                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1510                 rc = -EINVAL;
1511                 goto out;
1512         }
1513         offset += bytes_read;
1514         if (crypt_stat->file_version >= 1) {
1515                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1516                                            &bytes_read, validate_header_size);
1517                 if (rc) {
1518                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1519                                         "metadata; rc = [%d]\n", rc);
1520                 }
1521                 offset += bytes_read;
1522         } else
1523                 set_default_header_data(crypt_stat);
1524         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1525                                        ecryptfs_dentry);
1526 out:
1527         return rc;
1528 }
1529
1530 /**
1531  * ecryptfs_read_xattr_region
1532  * @page_virt: The vitual address into which to read the xattr data
1533  * @ecryptfs_inode: The eCryptfs inode
1534  *
1535  * Attempts to read the crypto metadata from the extended attribute
1536  * region of the lower file.
1537  *
1538  * Returns zero on success; non-zero on error
1539  */
1540 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1541 {
1542         struct dentry *lower_dentry =
1543                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1544         ssize_t size;
1545         int rc = 0;
1546
1547         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1548                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1549         if (size < 0) {
1550                 if (unlikely(ecryptfs_verbosity > 0))
1551                         printk(KERN_INFO "Error attempting to read the [%s] "
1552                                "xattr from the lower file; return value = "
1553                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1554                 rc = -EINVAL;
1555                 goto out;
1556         }
1557 out:
1558         return rc;
1559 }
1560
1561 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1562                                             struct inode *inode)
1563 {
1564         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1565         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1566         int rc;
1567
1568         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1569                                      ECRYPTFS_XATTR_NAME, file_size,
1570                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1571         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1572                 return rc >= 0 ? -EINVAL : rc;
1573         rc = ecryptfs_validate_marker(marker);
1574         if (!rc)
1575                 ecryptfs_i_size_init(file_size, inode);
1576         return rc;
1577 }
1578
1579 /**
1580  * ecryptfs_read_metadata
1581  *
1582  * Common entry point for reading file metadata. From here, we could
1583  * retrieve the header information from the header region of the file,
1584  * the xattr region of the file, or some other repostory that is
1585  * stored separately from the file itself. The current implementation
1586  * supports retrieving the metadata information from the file contents
1587  * and from the xattr region.
1588  *
1589  * Returns zero if valid headers found and parsed; non-zero otherwise
1590  */
1591 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1592 {
1593         int rc = 0;
1594         char *page_virt = NULL;
1595         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1596         struct ecryptfs_crypt_stat *crypt_stat =
1597             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1598         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1599                 &ecryptfs_superblock_to_private(
1600                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1601
1602         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1603                                                       mount_crypt_stat);
1604         /* Read the first page from the underlying file */
1605         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1606         if (!page_virt) {
1607                 rc = -ENOMEM;
1608                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1609                        __func__);
1610                 goto out;
1611         }
1612         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1613                                  ecryptfs_inode);
1614         if (rc >= 0)
1615                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1616                                                 ecryptfs_dentry,
1617                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1618         if (rc) {
1619                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1620                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1621                 if (rc) {
1622                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1623                                "file header region or xattr region\n");
1624                         rc = -EINVAL;
1625                         goto out;
1626                 }
1627                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1628                                                 ecryptfs_dentry,
1629                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1630                 if (rc) {
1631                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1632                                "file xattr region either\n");
1633                         rc = -EINVAL;
1634                 }
1635                 if (crypt_stat->mount_crypt_stat->flags
1636                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1637                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1638                 } else {
1639                         printk(KERN_WARNING "Attempt to access file with "
1640                                "crypto metadata only in the extended attribute "
1641                                "region, but eCryptfs was mounted without "
1642                                "xattr support enabled. eCryptfs will not treat "
1643                                "this like an encrypted file.\n");
1644                         rc = -EINVAL;
1645                 }
1646         }
1647 out:
1648         if (page_virt) {
1649                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1650                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1651         }
1652         return rc;
1653 }
1654
1655 /**
1656  * ecryptfs_encrypt_filename - encrypt filename
1657  *
1658  * CBC-encrypts the filename. We do not want to encrypt the same
1659  * filename with the same key and IV, which may happen with hard
1660  * links, so we prepend random bits to each filename.
1661  *
1662  * Returns zero on success; non-zero otherwise
1663  */
1664 static int
1665 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1666                           struct ecryptfs_crypt_stat *crypt_stat,
1667                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1668 {
1669         int rc = 0;
1670
1671         filename->encrypted_filename = NULL;
1672         filename->encrypted_filename_size = 0;
1673         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1674             || (mount_crypt_stat && (mount_crypt_stat->flags
1675                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1676                 size_t packet_size;
1677                 size_t remaining_bytes;
1678
1679                 rc = ecryptfs_write_tag_70_packet(
1680                         NULL, NULL,
1681                         &filename->encrypted_filename_size,
1682                         mount_crypt_stat, NULL,
1683                         filename->filename_size);
1684                 if (rc) {
1685                         printk(KERN_ERR "%s: Error attempting to get packet "
1686                                "size for tag 72; rc = [%d]\n", __func__,
1687                                rc);
1688                         filename->encrypted_filename_size = 0;
1689                         goto out;
1690                 }
1691                 filename->encrypted_filename =
1692                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1693                 if (!filename->encrypted_filename) {
1694                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1695                                "to kmalloc [%zd] bytes\n", __func__,
1696                                filename->encrypted_filename_size);
1697                         rc = -ENOMEM;
1698                         goto out;
1699                 }
1700                 remaining_bytes = filename->encrypted_filename_size;
1701                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1702                                                   &remaining_bytes,
1703                                                   &packet_size,
1704                                                   mount_crypt_stat,
1705                                                   filename->filename,
1706                                                   filename->filename_size);
1707                 if (rc) {
1708                         printk(KERN_ERR "%s: Error attempting to generate "
1709                                "tag 70 packet; rc = [%d]\n", __func__,
1710                                rc);
1711                         kfree(filename->encrypted_filename);
1712                         filename->encrypted_filename = NULL;
1713                         filename->encrypted_filename_size = 0;
1714                         goto out;
1715                 }
1716                 filename->encrypted_filename_size = packet_size;
1717         } else {
1718                 printk(KERN_ERR "%s: No support for requested filename "
1719                        "encryption method in this release\n", __func__);
1720                 rc = -EOPNOTSUPP;
1721                 goto out;
1722         }
1723 out:
1724         return rc;
1725 }
1726
1727 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1728                                   const char *name, size_t name_size)
1729 {
1730         int rc = 0;
1731
1732         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1733         if (!(*copied_name)) {
1734                 rc = -ENOMEM;
1735                 goto out;
1736         }
1737         memcpy((void *)(*copied_name), (void *)name, name_size);
1738         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1739                                                  * in printing out the
1740                                                  * string in debug
1741                                                  * messages */
1742         (*copied_name_size) = name_size;
1743 out:
1744         return rc;
1745 }
1746
1747 /**
1748  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1749  * @key_tfm: Crypto context for key material, set by this function
1750  * @cipher_name: Name of the cipher
1751  * @key_size: Size of the key in bytes
1752  *
1753  * Returns zero on success. Any crypto_tfm structs allocated here
1754  * should be released by other functions, such as on a superblock put
1755  * event, regardless of whether this function succeeds for fails.
1756  */
1757 static int
1758 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1759                             char *cipher_name, size_t *key_size)
1760 {
1761         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1762         char *full_alg_name = NULL;
1763         int rc;
1764
1765         *key_tfm = NULL;
1766         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1767                 rc = -EINVAL;
1768                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1769                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1770                 goto out;
1771         }
1772         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1773                                                     "ecb");
1774         if (rc)
1775                 goto out;
1776         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1777         if (IS_ERR(*key_tfm)) {
1778                 rc = PTR_ERR(*key_tfm);
1779                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1780                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1781                 goto out;
1782         }
1783         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1784         if (*key_size == 0) {
1785                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1786
1787                 *key_size = alg->max_keysize;
1788         }
1789         get_random_bytes(dummy_key, *key_size);
1790         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1791         if (rc) {
1792                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1793                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1794                        rc);
1795                 rc = -EINVAL;
1796                 goto out;
1797         }
1798 out:
1799         kfree(full_alg_name);
1800         return rc;
1801 }
1802
1803 struct kmem_cache *ecryptfs_key_tfm_cache;
1804 static struct list_head key_tfm_list;
1805 struct mutex key_tfm_list_mutex;
1806
1807 int __init ecryptfs_init_crypto(void)
1808 {
1809         mutex_init(&key_tfm_list_mutex);
1810         INIT_LIST_HEAD(&key_tfm_list);
1811         return 0;
1812 }
1813
1814 /**
1815  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1816  *
1817  * Called only at module unload time
1818  */
1819 int ecryptfs_destroy_crypto(void)
1820 {
1821         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1822
1823         mutex_lock(&key_tfm_list_mutex);
1824         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1825                                  key_tfm_list) {
1826                 list_del(&key_tfm->key_tfm_list);
1827                 if (key_tfm->key_tfm)
1828                         crypto_free_blkcipher(key_tfm->key_tfm);
1829                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1830         }
1831         mutex_unlock(&key_tfm_list_mutex);
1832         return 0;
1833 }
1834
1835 int
1836 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1837                          size_t key_size)
1838 {
1839         struct ecryptfs_key_tfm *tmp_tfm;
1840         int rc = 0;
1841
1842         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1843
1844         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1845         if (key_tfm != NULL)
1846                 (*key_tfm) = tmp_tfm;
1847         if (!tmp_tfm) {
1848                 rc = -ENOMEM;
1849                 printk(KERN_ERR "Error attempting to allocate from "
1850                        "ecryptfs_key_tfm_cache\n");
1851                 goto out;
1852         }
1853         mutex_init(&tmp_tfm->key_tfm_mutex);
1854         strncpy(tmp_tfm->cipher_name, cipher_name,
1855                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1856         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1857         tmp_tfm->key_size = key_size;
1858         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1859                                          tmp_tfm->cipher_name,
1860                                          &tmp_tfm->key_size);
1861         if (rc) {
1862                 printk(KERN_ERR "Error attempting to initialize key TFM "
1863                        "cipher with name = [%s]; rc = [%d]\n",
1864                        tmp_tfm->cipher_name, rc);
1865                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1866                 if (key_tfm != NULL)
1867                         (*key_tfm) = NULL;
1868                 goto out;
1869         }
1870         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1871 out:
1872         return rc;
1873 }
1874
1875 /**
1876  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1877  * @cipher_name: the name of the cipher to search for
1878  * @key_tfm: set to corresponding tfm if found
1879  *
1880  * Searches for cached key_tfm matching @cipher_name
1881  * Must be called with &key_tfm_list_mutex held
1882  * Returns 1 if found, with @key_tfm set
1883  * Returns 0 if not found, with @key_tfm set to NULL
1884  */
1885 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1886 {
1887         struct ecryptfs_key_tfm *tmp_key_tfm;
1888
1889         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1890
1891         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1892                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1893                         if (key_tfm)
1894                                 (*key_tfm) = tmp_key_tfm;
1895                         return 1;
1896                 }
1897         }
1898         if (key_tfm)
1899                 (*key_tfm) = NULL;
1900         return 0;
1901 }
1902
1903 /**
1904  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1905  *
1906  * @tfm: set to cached tfm found, or new tfm created
1907  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1908  * @cipher_name: the name of the cipher to search for and/or add
1909  *
1910  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1911  * Searches for cached item first, and creates new if not found.
1912  * Returns 0 on success, non-zero if adding new cipher failed
1913  */
1914 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1915                                                struct mutex **tfm_mutex,
1916                                                char *cipher_name)
1917 {
1918         struct ecryptfs_key_tfm *key_tfm;
1919         int rc = 0;
1920
1921         (*tfm) = NULL;
1922         (*tfm_mutex) = NULL;
1923
1924         mutex_lock(&key_tfm_list_mutex);
1925         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1926                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1927                 if (rc) {
1928                         printk(KERN_ERR "Error adding new key_tfm to list; "
1929                                         "rc = [%d]\n", rc);
1930                         goto out;
1931                 }
1932         }
1933         (*tfm) = key_tfm->key_tfm;
1934         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1935 out:
1936         mutex_unlock(&key_tfm_list_mutex);
1937         return rc;
1938 }
1939
1940 /* 64 characters forming a 6-bit target field */
1941 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1942                                                  "EFGHIJKLMNOPQRST"
1943                                                  "UVWXYZabcdefghij"
1944                                                  "klmnopqrstuvwxyz");
1945
1946 /* We could either offset on every reverse map or just pad some 0x00's
1947  * at the front here */
1948 static const unsigned char filename_rev_map[256] = {
1949         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1950         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1951         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1952         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1953         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1954         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1955         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1956         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1957         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1958         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1959         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1960         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1961         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1962         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1963         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1964         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1965 };
1966
1967 /**
1968  * ecryptfs_encode_for_filename
1969  * @dst: Destination location for encoded filename
1970  * @dst_size: Size of the encoded filename in bytes
1971  * @src: Source location for the filename to encode
1972  * @src_size: Size of the source in bytes
1973  */
1974 void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1975                                   unsigned char *src, size_t src_size)
1976 {
1977         size_t num_blocks;
1978         size_t block_num = 0;
1979         size_t dst_offset = 0;
1980         unsigned char last_block[3];
1981
1982         if (src_size == 0) {
1983                 (*dst_size) = 0;
1984                 goto out;
1985         }
1986         num_blocks = (src_size / 3);
1987         if ((src_size % 3) == 0) {
1988                 memcpy(last_block, (&src[src_size - 3]), 3);
1989         } else {
1990                 num_blocks++;
1991                 last_block[2] = 0x00;
1992                 switch (src_size % 3) {
1993                 case 1:
1994                         last_block[0] = src[src_size - 1];
1995                         last_block[1] = 0x00;
1996                         break;
1997                 case 2:
1998                         last_block[0] = src[src_size - 2];
1999                         last_block[1] = src[src_size - 1];
2000                 }
2001         }
2002         (*dst_size) = (num_blocks * 4);
2003         if (!dst)
2004                 goto out;
2005         while (block_num < num_blocks) {
2006                 unsigned char *src_block;
2007                 unsigned char dst_block[4];
2008
2009                 if (block_num == (num_blocks - 1))
2010                         src_block = last_block;
2011                 else
2012                         src_block = &src[block_num * 3];
2013                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
2014                 dst_block[1] = (((src_block[0] << 4) & 0x30)
2015                                 | ((src_block[1] >> 4) & 0x0F));
2016                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
2017                                 | ((src_block[2] >> 6) & 0x03));
2018                 dst_block[3] = (src_block[2] & 0x3F);
2019                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
2020                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
2021                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
2022                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
2023                 block_num++;
2024         }
2025 out:
2026         return;
2027 }
2028
2029 /**
2030  * ecryptfs_decode_from_filename
2031  * @dst: If NULL, this function only sets @dst_size and returns. If
2032  *       non-NULL, this function decodes the encoded octets in @src
2033  *       into the memory that @dst points to.
2034  * @dst_size: Set to the size of the decoded string.
2035  * @src: The encoded set of octets to decode.
2036  * @src_size: The size of the encoded set of octets to decode.
2037  */
2038 static void
2039 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
2040                               const unsigned char *src, size_t src_size)
2041 {
2042         u8 current_bit_offset = 0;
2043         size_t src_byte_offset = 0;
2044         size_t dst_byte_offset = 0;
2045
2046         if (dst == NULL) {
2047                 /* Not exact; conservatively long. Every block of 4
2048                  * encoded characters decodes into a block of 3
2049                  * decoded characters. This segment of code provides
2050                  * the caller with the maximum amount of allocated
2051                  * space that @dst will need to point to in a
2052                  * subsequent call. */
2053                 (*dst_size) = (((src_size + 1) * 3) / 4);
2054                 goto out;
2055         }
2056         while (src_byte_offset < src_size) {
2057                 unsigned char src_byte =
2058                                 filename_rev_map[(int)src[src_byte_offset]];
2059
2060                 switch (current_bit_offset) {
2061                 case 0:
2062                         dst[dst_byte_offset] = (src_byte << 2);
2063                         current_bit_offset = 6;
2064                         break;
2065                 case 6:
2066                         dst[dst_byte_offset++] |= (src_byte >> 4);
2067                         dst[dst_byte_offset] = ((src_byte & 0xF)
2068                                                  << 4);
2069                         current_bit_offset = 4;
2070                         break;
2071                 case 4:
2072                         dst[dst_byte_offset++] |= (src_byte >> 2);
2073                         dst[dst_byte_offset] = (src_byte << 6);
2074                         current_bit_offset = 2;
2075                         break;
2076                 case 2:
2077                         dst[dst_byte_offset++] |= (src_byte);
2078                         dst[dst_byte_offset] = 0;
2079                         current_bit_offset = 0;
2080                         break;
2081                 }
2082                 src_byte_offset++;
2083         }
2084         (*dst_size) = dst_byte_offset;
2085 out:
2086         return;
2087 }
2088
2089 /**
2090  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
2091  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
2092  * @name: The plaintext name
2093  * @length: The length of the plaintext
2094  * @encoded_name: The encypted name
2095  *
2096  * Encrypts and encodes a filename into something that constitutes a
2097  * valid filename for a filesystem, with printable characters.
2098  *
2099  * We assume that we have a properly initialized crypto context,
2100  * pointed to by crypt_stat->tfm.
2101  *
2102  * Returns zero on success; non-zero on otherwise
2103  */
2104 int ecryptfs_encrypt_and_encode_filename(
2105         char **encoded_name,
2106         size_t *encoded_name_size,
2107         struct ecryptfs_crypt_stat *crypt_stat,
2108         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2109         const char *name, size_t name_size)
2110 {
2111         size_t encoded_name_no_prefix_size;
2112         int rc = 0;
2113
2114         (*encoded_name) = NULL;
2115         (*encoded_name_size) = 0;
2116         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
2117             || (mount_crypt_stat && (mount_crypt_stat->flags
2118                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
2119                 struct ecryptfs_filename *filename;
2120
2121                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
2122                 if (!filename) {
2123                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2124                                "to kzalloc [%zd] bytes\n", __func__,
2125                                sizeof(*filename));
2126                         rc = -ENOMEM;
2127                         goto out;
2128                 }
2129                 filename->filename = (char *)name;
2130                 filename->filename_size = name_size;
2131                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
2132                                                mount_crypt_stat);
2133                 if (rc) {
2134                         printk(KERN_ERR "%s: Error attempting to encrypt "
2135                                "filename; rc = [%d]\n", __func__, rc);
2136                         kfree(filename);
2137                         goto out;
2138                 }
2139                 ecryptfs_encode_for_filename(
2140                         NULL, &encoded_name_no_prefix_size,
2141                         filename->encrypted_filename,
2142                         filename->encrypted_filename_size);
2143                 if ((crypt_stat && (crypt_stat->flags
2144                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2145                     || (mount_crypt_stat
2146                         && (mount_crypt_stat->flags
2147                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
2148                         (*encoded_name_size) =
2149                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2150                                  + encoded_name_no_prefix_size);
2151                 else
2152                         (*encoded_name_size) =
2153                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2154                                  + encoded_name_no_prefix_size);
2155                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
2156                 if (!(*encoded_name)) {
2157                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2158                                "to kzalloc [%zd] bytes\n", __func__,
2159                                (*encoded_name_size));
2160                         rc = -ENOMEM;
2161                         kfree(filename->encrypted_filename);
2162                         kfree(filename);
2163                         goto out;
2164                 }
2165                 if ((crypt_stat && (crypt_stat->flags
2166                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2167                     || (mount_crypt_stat
2168                         && (mount_crypt_stat->flags
2169                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2170                         memcpy((*encoded_name),
2171                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2172                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2173                         ecryptfs_encode_for_filename(
2174                             ((*encoded_name)
2175                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2176                             &encoded_name_no_prefix_size,
2177                             filename->encrypted_filename,
2178                             filename->encrypted_filename_size);
2179                         (*encoded_name_size) =
2180                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2181                                  + encoded_name_no_prefix_size);
2182                         (*encoded_name)[(*encoded_name_size)] = '\0';
2183                 } else {
2184                         rc = -EOPNOTSUPP;
2185                 }
2186                 if (rc) {
2187                         printk(KERN_ERR "%s: Error attempting to encode "
2188                                "encrypted filename; rc = [%d]\n", __func__,
2189                                rc);
2190                         kfree((*encoded_name));
2191                         (*encoded_name) = NULL;
2192                         (*encoded_name_size) = 0;
2193                 }
2194                 kfree(filename->encrypted_filename);
2195                 kfree(filename);
2196         } else {
2197                 rc = ecryptfs_copy_filename(encoded_name,
2198                                             encoded_name_size,
2199                                             name, name_size);
2200         }
2201 out:
2202         return rc;
2203 }
2204
2205 /**
2206  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2207  * @plaintext_name: The plaintext name
2208  * @plaintext_name_size: The plaintext name size
2209  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2210  * @name: The filename in cipher text
2211  * @name_size: The cipher text name size
2212  *
2213  * Decrypts and decodes the filename.
2214  *
2215  * Returns zero on error; non-zero otherwise
2216  */
2217 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2218                                          size_t *plaintext_name_size,
2219                                          struct dentry *ecryptfs_dir_dentry,
2220                                          const char *name, size_t name_size)
2221 {
2222         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2223                 &ecryptfs_superblock_to_private(
2224                         ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
2225         char *decoded_name;
2226         size_t decoded_name_size;
2227         size_t packet_size;
2228         int rc = 0;
2229
2230         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2231             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2232             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2233             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2234                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2235                 const char *orig_name = name;
2236                 size_t orig_name_size = name_size;
2237
2238                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2239                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2240                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2241                                               name, name_size);
2242                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2243                 if (!decoded_name) {
2244                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2245                                "to kmalloc [%zd] bytes\n", __func__,
2246                                decoded_name_size);
2247                         rc = -ENOMEM;
2248                         goto out;
2249                 }
2250                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2251                                               name, name_size);
2252                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2253                                                   plaintext_name_size,
2254                                                   &packet_size,
2255                                                   mount_crypt_stat,
2256                                                   decoded_name,
2257                                                   decoded_name_size);
2258                 if (rc) {
2259                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2260                                "from filename; copying through filename "
2261                                "as-is\n", __func__);
2262                         rc = ecryptfs_copy_filename(plaintext_name,
2263                                                     plaintext_name_size,
2264                                                     orig_name, orig_name_size);
2265                         goto out_free;
2266                 }
2267         } else {
2268                 rc = ecryptfs_copy_filename(plaintext_name,
2269                                             plaintext_name_size,
2270                                             name, name_size);
2271                 goto out;
2272         }
2273 out_free:
2274         kfree(decoded_name);
2275 out:
2276         return rc;
2277 }