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 "ecryptfs_kernel.h"
  37
  38 static int
  39 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
  40                              struct page *dst_page, int dst_offset,
  41                              struct page *src_page, int src_offset, int size,
  42                              unsigned char *iv);
  43 static int
  44 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
  45                              struct page *dst_page, int dst_offset,
  46                              struct page *src_page, int src_offset, int size,
  47                              unsigned char *iv);
  48
  49 /**
  50  * ecryptfs_to_hex
  51  * @dst: Buffer to take hex character representation of contents of
  52  *       src; must be at least of size (src_size * 2)
  53  * @src: Buffer to be converted to a hex string respresentation
  54  * @src_size: number of bytes to convert
  55  */
  56 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
  57 {
  58         int x;
  59
  60         for (x = 0; x < src_size; x++)
  61                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
  62 }
  63
  64 /**
  65  * ecryptfs_from_hex
  66  * @dst: Buffer to take the bytes from src hex; must be at least of
  67  *       size (src_size / 2)
  68  * @src: Buffer to be converted from a hex string respresentation to raw value
  69  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  70  */
  71 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  72 {
  73         int x;
  74         char tmp[3] = { 0, };
  75
  76         for (x = 0; x < dst_size; x++) {
  77                 tmp[0] = src[x * 2];
  78                 tmp[1] = src[x * 2 + 1];
  79                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  80         }
  81 }
  82
  83 /**
  84  * ecryptfs_calculate_md5 - calculates the md5 of @src
  85  * @dst: Pointer to 16 bytes of allocated memory
  86  * @crypt_stat: Pointer to crypt_stat struct for the current inode
  87  * @src: Data to be md5'd
  88  * @len: Length of @src
  89  *
  90  * Uses the allocated crypto context that crypt_stat references to
  91  * generate the MD5 sum of the contents of src.
  92  */
  93 static int ecryptfs_calculate_md5(char *dst,
  94                                   struct ecryptfs_crypt_stat *crypt_stat,
  95                                   char *src, int len)
  96 {
  97         struct scatterlist sg;
  98         struct hash_desc desc = {
  99                 .tfm = crypt_stat->hash_tfm,
 100                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 101         };
 102         int rc = 0;
 103
 104         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
 105         sg_init_one(&sg, (u8 *)src, len);
 106         if (!desc.tfm) {
 107                 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
 108                                              CRYPTO_ALG_ASYNC);
 109                 if (IS_ERR(desc.tfm)) {
 110                         rc = PTR_ERR(desc.tfm);
 111                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 112                                         "allocate crypto context; rc = [%d]\n",
 113                                         rc);
 114                         goto out;
 115                 }
 116                 crypt_stat->hash_tfm = desc.tfm;
 117         }
 118         crypto_hash_init(&desc);
 119         crypto_hash_update(&desc, &sg, len);
 120         crypto_hash_final(&desc, dst);
 121         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
 122 out:
 123         return rc;
 124 }
 125
 126 int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
 127                                            char *cipher_name,
 128                                            char *chaining_modifier)
 129 {
 130         int cipher_name_len = strlen(cipher_name);
 131         int chaining_modifier_len = strlen(chaining_modifier);
 132         int algified_name_len;
 133         int rc;
 134
 135         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
 136         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
 137         if (!(*algified_name)) {
 138                 rc = -ENOMEM;
 139                 goto out;
 140         }
 141         snprintf((*algified_name), algified_name_len, "%s(%s)",
 142                  chaining_modifier, cipher_name);
 143         rc = 0;
 144 out:
 145         return rc;
 146 }
 147
 148 /**
 149  * ecryptfs_derive_iv
 150  * @iv: destination for the derived iv vale
 151  * @crypt_stat: Pointer to crypt_stat struct for the current inode
 152  * @offset: Offset of the page whose's iv we are to derive
 153  *
 154  * Generate the initialization vector from the given root IV and page
 155  * offset.
 156  *
 157  * Returns zero on success; non-zero on error.
 158  */
 159 static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 160                               pgoff_t offset)
 161 {
 162         int rc = 0;
 163         char dst[MD5_DIGEST_SIZE];
 164         char src[ECRYPTFS_MAX_IV_BYTES + 16];
 165
 166         if (unlikely(ecryptfs_verbosity > 0)) {
 167                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 168                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 169         }
 170         /* TODO: It is probably secure to just cast the least
 171          * significant bits of the root IV into an unsigned long and
 172          * add the offset to that rather than go through all this
 173          * hashing business. -Halcrow */
 174         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 175         memset((src + crypt_stat->iv_bytes), 0, 16);
 176         snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset);
 177         if (unlikely(ecryptfs_verbosity > 0)) {
 178                 ecryptfs_printk(KERN_DEBUG, "source:\n");
 179                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 180         }
 181         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 182                                     (crypt_stat->iv_bytes + 16));
 183         if (rc) {
 184                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 185                                 "MD5 while generating IV for a page\n");
 186                 goto out;
 187         }
 188         memcpy(iv, dst, crypt_stat->iv_bytes);
 189         if (unlikely(ecryptfs_verbosity > 0)) {
 190                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 191                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 192         }
 193 out:
 194         return rc;
 195 }
 196
 197 /**
 198  * ecryptfs_init_crypt_stat
 199  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 200  *
 201  * Initialize the crypt_stat structure.
 202  */
 203 void
 204 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 205 {
 206         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 207         mutex_init(&crypt_stat->cs_mutex);
 208         mutex_init(&crypt_stat->cs_tfm_mutex);
 209         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
 210         ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED);
 211 }
 212
 213 /**
 214  * ecryptfs_destruct_crypt_stat
 215  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 216  *
 217  * Releases all memory associated with a crypt_stat struct.
 218  */
 219 void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 220 {
 221         if (crypt_stat->tfm)
 222                 crypto_free_blkcipher(crypt_stat->tfm);
 223         if (crypt_stat->hash_tfm)
 224                 crypto_free_hash(crypt_stat->hash_tfm);
 225         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 226 }
 227
 228 void ecryptfs_destruct_mount_crypt_stat(
 229         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 230 {
 231         if (mount_crypt_stat->global_auth_tok_key)
 232                 key_put(mount_crypt_stat->global_auth_tok_key);
 233         if (mount_crypt_stat->global_key_tfm)
 234                 crypto_free_blkcipher(mount_crypt_stat->global_key_tfm);
 235         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 236 }
 237
 238 /**
 239  * virt_to_scatterlist
 240  * @addr: Virtual address
 241  * @size: Size of data; should be an even multiple of the block size
 242  * @sg: Pointer to scatterlist array; set to NULL to obtain only
 243  *      the number of scatterlist structs required in array
 244  * @sg_size: Max array size
 245  *
 246  * Fills in a scatterlist array with page references for a passed
 247  * virtual address.
 248  *
 249  * Returns the number of scatterlist structs in array used
 250  */
 251 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 252                         int sg_size)
 253 {
 254         int i = 0;
 255         struct page *pg;
 256         int offset;
 257         int remainder_of_page;
 258
 259         while (size > 0 && i < sg_size) {
 260                 pg = virt_to_page(addr);
 261                 offset = offset_in_page(addr);
 262                 if (sg) {
 263                         sg[i].page = pg;
 264                         sg[i].offset = offset;
 265                 }
 266                 remainder_of_page = PAGE_CACHE_SIZE - offset;
 267                 if (size >= remainder_of_page) {
 268                         if (sg)
 269                                 sg[i].length = remainder_of_page;
 270                         addr += remainder_of_page;
 271                         size -= remainder_of_page;
 272                 } else {
 273                         if (sg)
 274                                 sg[i].length = size;
 275                         addr += size;
 276                         size = 0;
 277                 }
 278                 i++;
 279         }
 280         if (size > 0)
 281                 return -ENOMEM;
 282         return i;
 283 }
 284
 285 /**
 286  * encrypt_scatterlist
 287  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 288  * @dest_sg: Destination of encrypted data
 289  * @src_sg: Data to be encrypted
 290  * @size: Length of data to be encrypted
 291  * @iv: iv to use during encryption
 292  *
 293  * Returns the number of bytes encrypted; negative value on error
 294  */
 295 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 296                                struct scatterlist *dest_sg,
 297                                struct scatterlist *src_sg, int size,
 298                                unsigned char *iv)
 299 {
 300         struct blkcipher_desc desc = {
 301                 .tfm = crypt_stat->tfm,
 302                 .info = iv,
 303                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 304         };
 305         int rc = 0;
 306
 307         BUG_ON(!crypt_stat || !crypt_stat->tfm
 308                || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
 309                                        ECRYPTFS_STRUCT_INITIALIZED));
 310         if (unlikely(ecryptfs_verbosity > 0)) {
 311                 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
 312                                 crypt_stat->key_size);
 313                 ecryptfs_dump_hex(crypt_stat->key,
 314                                   crypt_stat->key_size);
 315         }
 316         /* Consider doing this once, when the file is opened */
 317         mutex_lock(&crypt_stat->cs_tfm_mutex);
 318         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 319                                      crypt_stat->key_size);
 320         if (rc) {
 321                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 322                                 rc);
 323                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 324                 rc = -EINVAL;
 325                 goto out;
 326         }
 327         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
 328         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
 329         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 330 out:
 331         return rc;
 332 }
 333
 334 static void
 335 ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
 336                                          int *byte_offset,
 337                                          struct ecryptfs_crypt_stat *crypt_stat,
 338                                          unsigned long extent_num)
 339 {
 340         unsigned long lower_extent_num;
 341         int extents_occupied_by_headers_at_front;
 342         int bytes_occupied_by_headers_at_front;
 343         int extent_offset;
 344         int extents_per_page;
 345
 346         bytes_occupied_by_headers_at_front =
 347                 ( crypt_stat->header_extent_size
 348                   * crypt_stat->num_header_extents_at_front );
 349         extents_occupied_by_headers_at_front =
 350                 ( bytes_occupied_by_headers_at_front
 351                   / crypt_stat->extent_size );
 352         lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
 353         extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
 354         (*lower_page_idx) = lower_extent_num / extents_per_page;
 355         extent_offset = lower_extent_num % extents_per_page;
 356         (*byte_offset) = extent_offset * crypt_stat->extent_size;
 357         ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = "
 358                         "[%d]\n", crypt_stat->header_extent_size);
 359         ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
 360                         "num_header_extents_at_front = [%d]\n",
 361                         crypt_stat->num_header_extents_at_front);
 362         ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
 363                         "front = [%d]\n", extents_occupied_by_headers_at_front);
 364         ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
 365                         lower_extent_num);
 366         ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
 367                         extents_per_page);
 368         ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
 369                         (*lower_page_idx));
 370         ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
 371                         extent_offset);
 372         ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
 373                         (*byte_offset));
 374 }
 375
 376 static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
 377                                    struct page *lower_page,
 378                                    struct inode *lower_inode,
 379                                    int byte_offset_in_page, int bytes_to_write)
 380 {
 381         int rc = 0;
 382
 383         if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
 384                 rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
 385                                                 ctx->param.lower_file,
 386                                                 byte_offset_in_page,
 387                                                 bytes_to_write);
 388                 if (rc) {
 389                         ecryptfs_printk(KERN_ERR, "Error calling lower "
 390                                         "commit; rc = [%d]\n", rc);
 391                         goto out;
 392                 }
 393         } else {
 394                 rc = ecryptfs_writepage_and_release_lower_page(lower_page,
 395                                                                lower_inode,
 396                                                                ctx->param.wbc);
 397                 if (rc) {
 398                         ecryptfs_printk(KERN_ERR, "Error calling lower "
 399                                         "writepage(); rc = [%d]\n", rc);
 400                         goto out;
 401                 }
 402         }
 403 out:
 404         return rc;
 405 }
 406
 407 static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
 408                                  struct page **lower_page,
 409                                  struct inode *lower_inode,
 410                                  unsigned long lower_page_idx,
 411                                  int byte_offset_in_page)
 412 {
 413         int rc = 0;
 414
 415         if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
 416                 /* TODO: Limit this to only the data extents that are
 417                  * needed */
 418                 rc = ecryptfs_get_lower_page(lower_page, lower_inode,
 419                                              ctx->param.lower_file,
 420                                              lower_page_idx,
 421                                              byte_offset_in_page,
 422                                              (PAGE_CACHE_SIZE
 423                                               - byte_offset_in_page));
 424                 if (rc) {
 425                         ecryptfs_printk(
 426                                 KERN_ERR, "Error attempting to grab, map, "
 427                                 "and prepare_write lower page with index "
 428                                 "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
 429                         goto out;
 430                 }
 431         } else {
 432                 *lower_page = grab_cache_page(lower_inode->i_mapping,
 433                                               lower_page_idx);
 434                 if (!(*lower_page)) {
 435                         rc = -EINVAL;
 436                         ecryptfs_printk(
 437                                 KERN_ERR, "Error attempting to grab and map "
 438                                 "lower page with index [0x%.16x]; rc = [%d]\n",
 439                                 lower_page_idx, rc);
 440                         goto out;
 441                 }
 442         }
 443 out:
 444         return rc;
 445 }
 446
 447 /**
 448  * ecryptfs_encrypt_page
 449  * @ctx: The context of the page
 450  *
 451  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 452  * that eCryptfs pages may straddle the lower pages -- for instance,
 453  * if the file was created on a machine with an 8K page size
 454  * (resulting in an 8K header), and then the file is copied onto a
 455  * host with a 32K page size, then when reading page 0 of the eCryptfs
 456  * file, 24K of page 0 of the lower file will be read and decrypted,
 457  * and then 8K of page 1 of the lower file will be read and decrypted.
 458  *
 459  * The actual operations performed on each page depends on the
 460  * contents of the ecryptfs_page_crypt_context struct.
 461  *
 462  * Returns zero on success; negative on error
 463  */
 464 int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
 465 {
 466         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 467         unsigned long base_extent;
 468         unsigned long extent_offset = 0;
 469         unsigned long lower_page_idx = 0;
 470         unsigned long prior_lower_page_idx = 0;
 471         struct page *lower_page;
 472         struct inode *lower_inode;
 473         struct ecryptfs_inode_info *inode_info;
 474         struct ecryptfs_crypt_stat *crypt_stat;
 475         int rc = 0;
 476         int lower_byte_offset = 0;
 477         int orig_byte_offset = 0;
 478         int num_extents_per_page;
 479 #define ECRYPTFS_PAGE_STATE_UNREAD    0
 480 #define ECRYPTFS_PAGE_STATE_READ      1
 481 #define ECRYPTFS_PAGE_STATE_MODIFIED  2
 482 #define ECRYPTFS_PAGE_STATE_WRITTEN   3
 483         int page_state;
 484
 485         lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
 486         inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
 487         crypt_stat = &inode_info->crypt_stat;
 488         if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
 489                 rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
 490                                                  ctx->param.lower_file);
 491                 if (rc)
 492                         ecryptfs_printk(KERN_ERR, "Error attempting to copy "
 493                                         "page at index [0x%.16x]\n",
 494                                         ctx->page->index);
 495                 goto out;
 496         }
 497         num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
 498         base_extent = (ctx->page->index * num_extents_per_page);
 499         page_state = ECRYPTFS_PAGE_STATE_UNREAD;
 500         while (extent_offset < num_extents_per_page) {
 501                 ecryptfs_extent_to_lwr_pg_idx_and_offset(
 502                         &lower_page_idx, &lower_byte_offset, crypt_stat,
 503                         (base_extent + extent_offset));
 504                 if (prior_lower_page_idx != lower_page_idx
 505                     && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
 506                         rc = ecryptfs_write_out_page(ctx, lower_page,
 507                                                      lower_inode,
 508                                                      orig_byte_offset,
 509                                                      (PAGE_CACHE_SIZE
 510                                                       - orig_byte_offset));
 511                         if (rc) {
 512                                 ecryptfs_printk(KERN_ERR, "Error attempting "
 513                                                 "to write out page; rc = [%d]"
 514                                                 "\n", rc);
 515                                 goto out;
 516                         }
 517                         page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
 518                 }
 519                 if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
 520                     || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
 521                         rc = ecryptfs_read_in_page(ctx, &lower_page,
 522                                                    lower_inode, lower_page_idx,
 523                                                    lower_byte_offset);
 524                         if (rc) {
 525                                 ecryptfs_printk(KERN_ERR, "Error attempting "
 526                                                 "to read in lower page with "
 527                                                 "index [0x%.16x]; rc = [%d]\n",
 528                                                 lower_page_idx, rc);
 529                                 goto out;
 530                         }
 531                         orig_byte_offset = lower_byte_offset;
 532                         prior_lower_page_idx = lower_page_idx;
 533                         page_state = ECRYPTFS_PAGE_STATE_READ;
 534                 }
 535                 BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
 536                          || page_state == ECRYPTFS_PAGE_STATE_READ));
 537                 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 538                                         (base_extent + extent_offset));
 539                 if (rc) {
 540                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 541                                         "derive IV for extent [0x%.16x]; "
 542                                         "rc = [%d]\n",
 543                                         (base_extent + extent_offset), rc);
 544                         goto out;
 545                 }
 546                 if (unlikely(ecryptfs_verbosity > 0)) {
 547                         ecryptfs_printk(KERN_DEBUG, "Encrypting 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                                         "encryption:\n");
 552                         ecryptfs_dump_hex((char *)
 553                                           (page_address(ctx->page)
 554                                            + (extent_offset
 555                                               * crypt_stat->extent_size)), 8);
 556                 }
 557                 rc = ecryptfs_encrypt_page_offset(
 558                         crypt_stat, lower_page, lower_byte_offset, ctx->page,
 559                         (extent_offset * crypt_stat->extent_size),
 560                         crypt_stat->extent_size, extent_iv);
 561                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
 562                                 "rc = [%d]\n",
 563                                 (base_extent + extent_offset), rc);
 564                 if (unlikely(ecryptfs_verbosity > 0)) {
 565                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 566                                         "encryption:\n");
 567                         ecryptfs_dump_hex((char *)(page_address(lower_page)
 568                                                    + lower_byte_offset), 8);
 569                 }
 570                 page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
 571                 extent_offset++;
 572         }
 573         BUG_ON(orig_byte_offset != 0);
 574         rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
 575                                      (lower_byte_offset
 576                                       + crypt_stat->extent_size));
 577         if (rc) {
 578                 ecryptfs_printk(KERN_ERR, "Error attempting to write out "
 579                                 "page; rc = [%d]\n", rc);
 580                                 goto out;
 581         }
 582 out:
 583         return rc;
 584 }
 585
 586 /**
 587  * ecryptfs_decrypt_page
 588  * @file: The ecryptfs file
 589  * @page: The page in ecryptfs to decrypt
 590  *
 591  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 592  * that eCryptfs pages may straddle the lower pages -- for instance,
 593  * if the file was created on a machine with an 8K page size
 594  * (resulting in an 8K header), and then the file is copied onto a
 595  * host with a 32K page size, then when reading page 0 of the eCryptfs
 596  * file, 24K of page 0 of the lower file will be read and decrypted,
 597  * and then 8K of page 1 of the lower file will be read and decrypted.
 598  *
 599  * Returns zero on success; negative on error
 600  */
 601 int ecryptfs_decrypt_page(struct file *file, struct page *page)
 602 {
 603         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 604         unsigned long base_extent;
 605         unsigned long extent_offset = 0;
 606         unsigned long lower_page_idx = 0;
 607         unsigned long prior_lower_page_idx = 0;
 608         struct page *lower_page;
 609         char *lower_page_virt = NULL;
 610         struct inode *lower_inode;
 611         struct ecryptfs_crypt_stat *crypt_stat;
 612         int rc = 0;
 613         int byte_offset;
 614         int num_extents_per_page;
 615         int page_state;
 616
 617         crypt_stat = &(ecryptfs_inode_to_private(
 618                                page->mapping->host)->crypt_stat);
 619         lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
 620         if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
 621                 rc = ecryptfs_do_readpage(file, page, page->index);
 622                 if (rc)
 623                         ecryptfs_printk(KERN_ERR, "Error attempting to copy "
 624                                         "page at index [0x%.16x]\n",
 625                                         page->index);
 626                 goto out;
 627         }
 628         num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
 629         base_extent = (page->index * num_extents_per_page);
 630         lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
 631                                            GFP_KERNEL);
 632         if (!lower_page_virt) {
 633                 rc = -ENOMEM;
 634                 ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
 635                                 "lower page(s)\n");
 636                 goto out;
 637         }
 638         lower_page = virt_to_page(lower_page_virt);
 639         page_state = ECRYPTFS_PAGE_STATE_UNREAD;
 640         while (extent_offset < num_extents_per_page) {
 641                 ecryptfs_extent_to_lwr_pg_idx_and_offset(
 642                         &lower_page_idx, &byte_offset, crypt_stat,
 643                         (base_extent + extent_offset));
 644                 if (prior_lower_page_idx != lower_page_idx
 645                     || page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
 646                         rc = ecryptfs_do_readpage(file, lower_page,
 647                                                   lower_page_idx);
 648                         if (rc) {
 649                                 ecryptfs_printk(KERN_ERR, "Error reading "
 650                                                 "lower encrypted page; rc = "
 651                                                 "[%d]\n", rc);
 652                                 goto out;
 653                         }
 654                         prior_lower_page_idx = lower_page_idx;
 655                         page_state = ECRYPTFS_PAGE_STATE_READ;
 656                 }
 657                 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 658                                         (base_extent + extent_offset));
 659                 if (rc) {
 660                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 661                                         "derive IV for extent [0x%.16x]; rc = "
 662                                         "[%d]\n",
 663                                         (base_extent + extent_offset), rc);
 664                         goto out;
 665                 }
 666                 if (unlikely(ecryptfs_verbosity > 0)) {
 667                         ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
 668                                         "with iv:\n");
 669                         ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
 670                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
 671                                         "decryption:\n");
 672                         ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
 673                 }
 674                 rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
 675                                                   (extent_offset
 676                                                    * crypt_stat->extent_size),
 677                                                   lower_page, byte_offset,
 678                                                   crypt_stat->extent_size,
 679                                                   extent_iv);
 680                 if (rc != crypt_stat->extent_size) {
 681                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 682                                         "decrypt extent [0x%.16x]\n",
 683                                         (base_extent + extent_offset));
 684                         goto out;
 685                 }
 686                 rc = 0;
 687                 if (unlikely(ecryptfs_verbosity > 0)) {
 688                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 689                                         "decryption:\n");
 690                         ecryptfs_dump_hex((char *)(page_address(page)
 691                                                    + byte_offset), 8);
 692                 }
 693                 extent_offset++;
 694         }
 695 out:
 696         if (lower_page_virt)
 697                 kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
 698         return rc;
 699 }
 700
 701 /**
 702  * decrypt_scatterlist
 703  *
 704  * Returns the number of bytes decrypted; negative value on error
 705  */
 706 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 707                                struct scatterlist *dest_sg,
 708                                struct scatterlist *src_sg, int size,
 709                                unsigned char *iv)
 710 {
 711         struct blkcipher_desc desc = {
 712                 .tfm = crypt_stat->tfm,
 713                 .info = iv,
 714                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 715         };
 716         int rc = 0;
 717
 718         /* Consider doing this once, when the file is opened */
 719         mutex_lock(&crypt_stat->cs_tfm_mutex);
 720         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 721                                      crypt_stat->key_size);
 722         if (rc) {
 723                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 724                                 rc);
 725                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 726                 rc = -EINVAL;
 727                 goto out;
 728         }
 729         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
 730         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
 731         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 732         if (rc) {
 733                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
 734                                 rc);
 735                 goto out;
 736         }
 737         rc = size;
 738 out:
 739         return rc;
 740 }
 741
 742 /**
 743  * ecryptfs_encrypt_page_offset
 744  *
 745  * Returns the number of bytes encrypted
 746  */
 747 static int
 748 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 749                              struct page *dst_page, int dst_offset,
 750                              struct page *src_page, int src_offset, int size,
 751                              unsigned char *iv)
 752 {
 753         struct scatterlist src_sg, dst_sg;
 754
 755         src_sg.page = src_page;
 756         src_sg.offset = src_offset;
 757         src_sg.length = size;
 758         dst_sg.page = dst_page;
 759         dst_sg.offset = dst_offset;
 760         dst_sg.length = size;
 761         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 762 }
 763
 764 /**
 765  * ecryptfs_decrypt_page_offset
 766  *
 767  * Returns the number of bytes decrypted
 768  */
 769 static int
 770 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 771                              struct page *dst_page, int dst_offset,
 772                              struct page *src_page, int src_offset, int size,
 773                              unsigned char *iv)
 774 {
 775         struct scatterlist src_sg, dst_sg;
 776
 777         src_sg.page = src_page;
 778         src_sg.offset = src_offset;
 779         src_sg.length = size;
 780         dst_sg.page = dst_page;
 781         dst_sg.offset = dst_offset;
 782         dst_sg.length = size;
 783         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 784 }
 785
 786 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 787
 788 /**
 789  * ecryptfs_init_crypt_ctx
 790  * @crypt_stat: Uninitilized crypt stats structure
 791  *
 792  * Initialize the crypto context.
 793  *
 794  * TODO: Performance: Keep a cache of initialized cipher contexts;
 795  * only init if needed
 796  */
 797 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 798 {
 799         char *full_alg_name;
 800         int rc = -EINVAL;
 801
 802         if (!crypt_stat->cipher) {
 803                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
 804                 goto out;
 805         }
 806         ecryptfs_printk(KERN_DEBUG,
 807                         "Initializing cipher [%s]; strlen = [%d]; "
 808                         "key_size_bits = [%d]\n",
 809                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 810                         crypt_stat->key_size << 3);
 811         if (crypt_stat->tfm) {
 812                 rc = 0;
 813                 goto out;
 814         }
 815         mutex_lock(&crypt_stat->cs_tfm_mutex);
 816         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 817                                                     crypt_stat->cipher, "cbc");
 818         if (rc)
 819                 goto out;
 820         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
 821                                                  CRYPTO_ALG_ASYNC);
 822         kfree(full_alg_name);
 823         if (IS_ERR(crypt_stat->tfm)) {
 824                 rc = PTR_ERR(crypt_stat->tfm);
 825                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 826                                 "Error initializing cipher [%s]\n",
 827                                 crypt_stat->cipher);
 828                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 829                 goto out;
 830         }
 831         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 832         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 833         rc = 0;
 834 out:
 835         return rc;
 836 }
 837
 838 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 839 {
 840         int extent_size_tmp;
 841
 842         crypt_stat->extent_mask = 0xFFFFFFFF;
 843         crypt_stat->extent_shift = 0;
 844         if (crypt_stat->extent_size == 0)
 845                 return;
 846         extent_size_tmp = crypt_stat->extent_size;
 847         while ((extent_size_tmp & 0x01) == 0) {
 848                 extent_size_tmp >>= 1;
 849                 crypt_stat->extent_mask <<= 1;
 850                 crypt_stat->extent_shift++;
 851         }
 852 }
 853
 854 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 855 {
 856         /* Default values; may be overwritten as we are parsing the
 857          * packets. */
 858         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 859         set_extent_mask_and_shift(crypt_stat);
 860         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 861         if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
 862                 crypt_stat->header_extent_size =
 863                         ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 864         } else
 865                 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
 866         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 867                 crypt_stat->num_header_extents_at_front = 0;
 868         else
 869                 crypt_stat->num_header_extents_at_front = 1;
 870 }
 871
 872 /**
 873  * ecryptfs_compute_root_iv
 874  * @crypt_stats
 875  *
 876  * On error, sets the root IV to all 0's.
 877  */
 878 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 879 {
 880         int rc = 0;
 881         char dst[MD5_DIGEST_SIZE];
 882
 883         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 884         BUG_ON(crypt_stat->iv_bytes <= 0);
 885         if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) {
 886                 rc = -EINVAL;
 887                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 888                                 "cannot generate root IV\n");
 889                 goto out;
 890         }
 891         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 892                                     crypt_stat->key_size);
 893         if (rc) {
 894                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 895                                 "MD5 while generating root IV\n");
 896                 goto out;
 897         }
 898         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 899 out:
 900         if (rc) {
 901                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 902                 ECRYPTFS_SET_FLAG(crypt_stat->flags,
 903                                   ECRYPTFS_SECURITY_WARNING);
 904         }
 905         return rc;
 906 }
 907
 908 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 909 {
 910         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 911         ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
 912         ecryptfs_compute_root_iv(crypt_stat);
 913         if (unlikely(ecryptfs_verbosity > 0)) {
 914                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 915                 ecryptfs_dump_hex(crypt_stat->key,
 916                                   crypt_stat->key_size);
 917         }
 918 }
 919
 920 /**
 921  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 922  *
 923  * This function propagates the mount-wide flags to individual inode
 924  * flags.
 925  */
 926 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 927         struct ecryptfs_crypt_stat *crypt_stat,
 928         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 929 {
 930         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 931                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 932         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 933                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 934 }
 935
 936 /**
 937  * ecryptfs_set_default_crypt_stat_vals
 938  * @crypt_stat
 939  *
 940  * Default values in the event that policy does not override them.
 941  */
 942 static void ecryptfs_set_default_crypt_stat_vals(
 943         struct ecryptfs_crypt_stat *crypt_stat,
 944         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 945 {
 946         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 947                                                       mount_crypt_stat);
 948         ecryptfs_set_default_sizes(crypt_stat);
 949         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 950         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 951         ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
 952         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 953         crypt_stat->mount_crypt_stat = mount_crypt_stat;
 954 }
 955
 956 /**
 957  * ecryptfs_new_file_context
 958  * @ecryptfs_dentry
 959  *
 960  * If the crypto context for the file has not yet been established,
 961  * this is where we do that.  Establishing a new crypto context
 962  * involves the following decisions:
 963  *  - What cipher to use?
 964  *  - What set of authentication tokens to use?
 965  * Here we just worry about getting enough information into the
 966  * authentication tokens so that we know that they are available.
 967  * We associate the available authentication tokens with the new file
 968  * via the set of signatures in the crypt_stat struct.  Later, when
 969  * the headers are actually written out, we may again defer to
 970  * userspace to perform the encryption of the session key; for the
 971  * foreseeable future, this will be the case with public key packets.
 972  *
 973  * Returns zero on success; non-zero otherwise
 974  */
 975 /* Associate an authentication token(s) with the file */
 976 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
 977 {
 978         int rc = 0;
 979         struct ecryptfs_crypt_stat *crypt_stat =
 980             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
 981         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 982             &ecryptfs_superblock_to_private(
 983                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
 984         int cipher_name_len;
 985
 986         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 987         /* See if there are mount crypt options */
 988         if (mount_crypt_stat->global_auth_tok) {
 989                 ecryptfs_printk(KERN_DEBUG, "Initializing context for new "
 990                                 "file using mount_crypt_stat\n");
 991                 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
 992                 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
 993                 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 994                                                               mount_crypt_stat);
 995                 memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++],
 996                        mount_crypt_stat->global_auth_tok_sig,
 997                        ECRYPTFS_SIG_SIZE_HEX);
 998                 cipher_name_len =
 999                     strlen(mount_crypt_stat->global_default_cipher_name);
1000                 memcpy(crypt_stat->cipher,
1001                        mount_crypt_stat->global_default_cipher_name,
1002                        cipher_name_len);
1003                 crypt_stat->cipher[cipher_name_len] = '\0';
1004                 crypt_stat->key_size =
1005                         mount_crypt_stat->global_default_cipher_key_size;
1006                 ecryptfs_generate_new_key(crypt_stat);
1007         } else
1008                 /* We should not encounter this scenario since we
1009                  * should detect lack of global_auth_tok at mount time
1010                  * TODO: Applies to 0.1 release only; remove in future
1011                  * release */
1012                 BUG();
1013         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1014         if (rc)
1015                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1016                                 "context for cipher [%s]: rc = [%d]\n",
1017                                 crypt_stat->cipher, rc);
1018         return rc;
1019 }
1020
1021 /**
1022  * contains_ecryptfs_marker - check for the ecryptfs marker
1023  * @data: The data block in which to check
1024  *
1025  * Returns one if marker found; zero if not found
1026  */
1027 static int contains_ecryptfs_marker(char *data)
1028 {
1029         u32 m_1, m_2;
1030
1031         memcpy(&m_1, data, 4);
1032         m_1 = be32_to_cpu(m_1);
1033         memcpy(&m_2, (data + 4), 4);
1034         m_2 = be32_to_cpu(m_2);
1035         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1036                 return 1;
1037         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1038                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1039                         MAGIC_ECRYPTFS_MARKER);
1040         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1041                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1042         return 0;
1043 }
1044
1045 struct ecryptfs_flag_map_elem {
1046         u32 file_flag;
1047         u32 local_flag;
1048 };
1049
1050 /* Add support for additional flags by adding elements here. */
1051 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1052         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1053         {0x00000002, ECRYPTFS_ENCRYPTED},
1054         {0x00000004, ECRYPTFS_METADATA_IN_XATTR}
1055 };
1056
1057 /**
1058  * ecryptfs_process_flags
1059  * @crypt_stat
1060  * @page_virt: Source data to be parsed
1061  * @bytes_read: Updated with the number of bytes read
1062  *
1063  * Returns zero on success; non-zero if the flag set is invalid
1064  */
1065 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1066                                   char *page_virt, int *bytes_read)
1067 {
1068         int rc = 0;
1069         int i;
1070         u32 flags;
1071
1072         memcpy(&flags, page_virt, 4);
1073         flags = be32_to_cpu(flags);
1074         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1075                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1076                 if (flags & ecryptfs_flag_map[i].file_flag) {
1077                         ECRYPTFS_SET_FLAG(crypt_stat->flags,
1078                                           ecryptfs_flag_map[i].local_flag);
1079                 } else
1080                         ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
1081                                             ecryptfs_flag_map[i].local_flag);
1082         /* Version is in top 8 bits of the 32-bit flag vector */
1083         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1084         (*bytes_read) = 4;
1085         return rc;
1086 }
1087
1088 /**
1089  * write_ecryptfs_marker
1090  * @page_virt: The pointer to in a page to begin writing the marker
1091  * @written: Number of bytes written
1092  *
1093  * Marker = 0x3c81b7f5
1094  */
1095 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1096 {
1097         u32 m_1, m_2;
1098
1099         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1100         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1101         m_1 = cpu_to_be32(m_1);
1102         memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1103         m_2 = cpu_to_be32(m_2);
1104         memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1105                (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1106         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1107 }
1108
1109 static void
1110 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1111                      size_t *written)
1112 {
1113         u32 flags = 0;
1114         int i;
1115
1116         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1117                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1118                 if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1119                                         ecryptfs_flag_map[i].local_flag))
1120                         flags |= ecryptfs_flag_map[i].file_flag;
1121         /* Version is in top 8 bits of the 32-bit flag vector */
1122         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1123         flags = cpu_to_be32(flags);
1124         memcpy(page_virt, &flags, 4);
1125         (*written) = 4;
1126 }
1127
1128 struct ecryptfs_cipher_code_str_map_elem {
1129         char cipher_str[16];
1130         u16 cipher_code;
1131 };
1132
1133 /* Add support for additional ciphers by adding elements here. The
1134  * cipher_code is whatever OpenPGP applicatoins use to identify the
1135  * ciphers. List in order of probability. */
1136 static struct ecryptfs_cipher_code_str_map_elem
1137 ecryptfs_cipher_code_str_map[] = {
1138         {"aes",RFC2440_CIPHER_AES_128 },
1139         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1140         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1141         {"cast5", RFC2440_CIPHER_CAST_5},
1142         {"twofish", RFC2440_CIPHER_TWOFISH},
1143         {"cast6", RFC2440_CIPHER_CAST_6},
1144         {"aes", RFC2440_CIPHER_AES_192},
1145         {"aes", RFC2440_CIPHER_AES_256}
1146 };
1147
1148 /**
1149  * ecryptfs_code_for_cipher_string
1150  * @str: The string representing the cipher name
1151  *
1152  * Returns zero on no match, or the cipher code on match
1153  */
1154 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1155 {
1156         int i;
1157         u16 code = 0;
1158         struct ecryptfs_cipher_code_str_map_elem *map =
1159                 ecryptfs_cipher_code_str_map;
1160
1161         if (strcmp(crypt_stat->cipher, "aes") == 0) {
1162                 switch (crypt_stat->key_size) {
1163                 case 16:
1164                         code = RFC2440_CIPHER_AES_128;
1165                         break;
1166                 case 24:
1167                         code = RFC2440_CIPHER_AES_192;
1168                         break;
1169                 case 32:
1170                         code = RFC2440_CIPHER_AES_256;
1171                 }
1172         } else {
1173                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1174                         if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1175                                 code = map[i].cipher_code;
1176                                 break;
1177                         }
1178         }
1179         return code;
1180 }
1181
1182 /**
1183  * ecryptfs_cipher_code_to_string
1184  * @str: Destination to write out the cipher name
1185  * @cipher_code: The code to convert to cipher name string
1186  *
1187  * Returns zero on success
1188  */
1189 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1190 {
1191         int rc = 0;
1192         int i;
1193
1194         str[0] = '\0';
1195         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1196                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1197                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1198         if (str[0] == '\0') {
1199                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1200                                 "[%d]\n", cipher_code);
1201                 rc = -EINVAL;
1202         }
1203         return rc;
1204 }
1205
1206 /**
1207  * ecryptfs_read_header_region
1208  * @data
1209  * @dentry
1210  * @nd
1211  *
1212  * Returns zero on success; non-zero otherwise
1213  */
1214 static int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1215                                        struct vfsmount *mnt)
1216 {
1217         struct file *lower_file;
1218         mm_segment_t oldfs;
1219         int rc;
1220
1221         if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
1222                                            O_RDONLY))) {
1223                 printk(KERN_ERR
1224                        "Error opening lower_file to read header region\n");
1225                 goto out;
1226         }
1227         lower_file->f_pos = 0;
1228         oldfs = get_fs();
1229         set_fs(get_ds());
1230         /* For releases 0.1 and 0.2, all of the header information
1231          * fits in the first data extent-sized region. */
1232         rc = lower_file->f_op->read(lower_file, (char __user *)data,
1233                               ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
1234         set_fs(oldfs);
1235         if ((rc = ecryptfs_close_lower_file(lower_file))) {
1236                 printk(KERN_ERR "Error closing lower_file\n");
1237                 goto out;
1238         }
1239         rc = 0;
1240 out:
1241         return rc;
1242 }
1243
1244 int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
1245                                              struct vfsmount *mnt)
1246 {
1247         int rc;
1248
1249         rc = ecryptfs_read_header_region(data, dentry, mnt);
1250         if (rc)
1251                 goto out;
1252         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES))
1253                 rc = -EINVAL;
1254 out:
1255         return rc;
1256 }
1257
1258
1259 void
1260 ecryptfs_write_header_metadata(char *virt,
1261                                struct ecryptfs_crypt_stat *crypt_stat,
1262                                size_t *written)
1263 {
1264         u32 header_extent_size;
1265         u16 num_header_extents_at_front;
1266
1267         header_extent_size = (u32)crypt_stat->header_extent_size;
1268         num_header_extents_at_front =
1269                 (u16)crypt_stat->num_header_extents_at_front;
1270         header_extent_size = cpu_to_be32(header_extent_size);
1271         memcpy(virt, &header_extent_size, 4);
1272         virt += 4;
1273         num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1274         memcpy(virt, &num_header_extents_at_front, 2);
1275         (*written) = 6;
1276 }
1277
1278 struct kmem_cache *ecryptfs_header_cache_0;
1279 struct kmem_cache *ecryptfs_header_cache_1;
1280 struct kmem_cache *ecryptfs_header_cache_2;
1281
1282 /**
1283  * ecryptfs_write_headers_virt
1284  * @page_virt
1285  * @crypt_stat
1286  * @ecryptfs_dentry
1287  *
1288  * Format version: 1
1289  *
1290  *   Header Extent:
1291  *     Octets 0-7:        Unencrypted file size (big-endian)
1292  *     Octets 8-15:       eCryptfs special marker
1293  *     Octets 16-19:      Flags
1294  *      Octet 16:         File format version number (between 0 and 255)
1295  *      Octets 17-18:     Reserved
1296  *      Octet 19:         Bit 1 (lsb): Reserved
1297  *                        Bit 2: Encrypted?
1298  *                        Bits 3-8: Reserved
1299  *     Octets 20-23:      Header extent size (big-endian)
1300  *     Octets 24-25:      Number of header extents at front of file
1301  *                        (big-endian)
1302  *     Octet  26:         Begin RFC 2440 authentication token packet set
1303  *   Data Extent 0:
1304  *     Lower data (CBC encrypted)
1305  *   Data Extent 1:
1306  *     Lower data (CBC encrypted)
1307  *   ...
1308  *
1309  * Returns zero on success
1310  */
1311 static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
1312                                        struct ecryptfs_crypt_stat *crypt_stat,
1313                                        struct dentry *ecryptfs_dentry)
1314 {
1315         int rc;
1316         size_t written;
1317         size_t offset;
1318
1319         offset = ECRYPTFS_FILE_SIZE_BYTES;
1320         write_ecryptfs_marker((page_virt + offset), &written);
1321         offset += written;
1322         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1323         offset += written;
1324         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1325                                        &written);
1326         offset += written;
1327         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1328                                               ecryptfs_dentry, &written,
1329                                               PAGE_CACHE_SIZE - offset);
1330         if (rc)
1331                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1332                                 "set; rc = [%d]\n", rc);
1333         if (size) {
1334                 offset += written;
1335                 *size = offset;
1336         }
1337         return rc;
1338 }
1339
1340 static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
1341                                                struct file *lower_file,
1342                                                char *page_virt)
1343 {
1344         mm_segment_t oldfs;
1345         int current_header_page;
1346         int header_pages;
1347         ssize_t size;
1348         int rc = 0;
1349
1350         lower_file->f_pos = 0;
1351         oldfs = get_fs();
1352         set_fs(get_ds());
1353         size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE,
1354                          &lower_file->f_pos);
1355         if (size < 0) {
1356                 rc = (int)size;
1357                 printk(KERN_ERR "Error attempting to write lower page; "
1358                        "rc = [%d]\n", rc);
1359                 set_fs(oldfs);
1360                 goto out;
1361         }
1362         header_pages = ((crypt_stat->header_extent_size
1363                          * crypt_stat->num_header_extents_at_front)
1364                         / PAGE_CACHE_SIZE);
1365         memset(page_virt, 0, PAGE_CACHE_SIZE);
1366         current_header_page = 1;
1367         while (current_header_page < header_pages) {
1368                 size = vfs_write(lower_file, (char __user *)page_virt,
1369                                  PAGE_CACHE_SIZE, &lower_file->f_pos);
1370                 if (size < 0) {
1371                         rc = (int)size;
1372                         printk(KERN_ERR "Error attempting to write lower page; "
1373                                "rc = [%d]\n", rc);
1374                         set_fs(oldfs);
1375                         goto out;
1376                 }
1377                 current_header_page++;
1378         }
1379         set_fs(oldfs);
1380 out:
1381         return rc;
1382 }
1383
1384 static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1385                                             struct ecryptfs_crypt_stat *crypt_stat,
1386                                             char *page_virt, size_t size)
1387 {
1388         int rc;
1389
1390         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1391                                size, 0);
1392         return rc;
1393 }
1394
1395 /**
1396  * ecryptfs_write_metadata
1397  * @lower_file: The lower file struct, which was returned from dentry_open
1398  *
1399  * Write the file headers out.  This will likely involve a userspace
1400  * callout, in which the session key is encrypted with one or more
1401  * public keys and/or the passphrase necessary to do the encryption is
1402  * retrieved via a prompt.  Exactly what happens at this point should
1403  * be policy-dependent.
1404  *
1405  * Returns zero on success; non-zero on error
1406  */
1407 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1408                             struct file *lower_file)
1409 {
1410         struct ecryptfs_crypt_stat *crypt_stat;
1411         char *page_virt;
1412         size_t size;
1413         int rc = 0;
1414
1415         crypt_stat = &ecryptfs_inode_to_private(
1416                 ecryptfs_dentry->d_inode)->crypt_stat;
1417         if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1418                                        ECRYPTFS_ENCRYPTED))) {
1419                 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1420                                          ECRYPTFS_KEY_VALID)) {
1421                         ecryptfs_printk(KERN_DEBUG, "Key is "
1422                                         "invalid; bailing out\n");
1423                         rc = -EINVAL;
1424                         goto out;
1425                 }
1426         } else {
1427                 rc = -EINVAL;
1428                 ecryptfs_printk(KERN_WARNING,
1429                                 "Called with crypt_stat->encrypted == 0\n");
1430                 goto out;
1431         }
1432         /* Released in this function */
1433         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
1434         if (!page_virt) {
1435                 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1436                 rc = -ENOMEM;
1437                 goto out;
1438         }
1439         rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
1440                                          ecryptfs_dentry);
1441         if (unlikely(rc)) {
1442                 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1443                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1444                 goto out_free;
1445         }
1446         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1447                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
1448                                                       crypt_stat, page_virt,
1449                                                       size);
1450         else
1451                 rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file,
1452                                                          page_virt);
1453         if (rc) {
1454                 printk(KERN_ERR "Error writing metadata out to lower file; "
1455                        "rc = [%d]\n", rc);
1456                 goto out_free;
1457         }
1458 out_free:
1459         kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1460 out:
1461         return rc;
1462 }
1463
1464 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1465 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1466 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1467                                  char *virt, int *bytes_read,
1468                                  int validate_header_size)
1469 {
1470         int rc = 0;
1471         u32 header_extent_size;
1472         u16 num_header_extents_at_front;
1473
1474         memcpy(&header_extent_size, virt, 4);
1475         header_extent_size = be32_to_cpu(header_extent_size);
1476         virt += 4;
1477         memcpy(&num_header_extents_at_front, virt, 2);
1478         num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1479         crypt_stat->header_extent_size = (int)header_extent_size;
1480         crypt_stat->num_header_extents_at_front =
1481                 (int)num_header_extents_at_front;
1482         (*bytes_read) = 6;
1483         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1484             && ((crypt_stat->header_extent_size
1485                  * crypt_stat->num_header_extents_at_front)
1486                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1487                 rc = -EINVAL;
1488                 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1489                                 "[%d]\n", crypt_stat->header_extent_size);
1490         }
1491         return rc;
1492 }
1493
1494 /**
1495  * set_default_header_data
1496  *
1497  * For version 0 file format; this function is only for backwards
1498  * compatibility for files created with the prior versions of
1499  * eCryptfs.
1500  */
1501 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1502 {
1503         crypt_stat->header_extent_size = 4096;
1504         crypt_stat->num_header_extents_at_front = 1;
1505 }
1506
1507 /**
1508  * ecryptfs_read_headers_virt
1509  *
1510  * Read/parse the header data. The header format is detailed in the
1511  * comment block for the ecryptfs_write_headers_virt() function.
1512  *
1513  * Returns zero on success
1514  */
1515 static int ecryptfs_read_headers_virt(char *page_virt,
1516                                       struct ecryptfs_crypt_stat *crypt_stat,
1517                                       struct dentry *ecryptfs_dentry,
1518                                       int validate_header_size)
1519 {
1520         int rc = 0;
1521         int offset;
1522         int bytes_read;
1523
1524         ecryptfs_set_default_sizes(crypt_stat);
1525         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1526                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1527         offset = ECRYPTFS_FILE_SIZE_BYTES;
1528         rc = contains_ecryptfs_marker(page_virt + offset);
1529         if (rc == 0) {
1530                 rc = -EINVAL;
1531                 goto out;
1532         }
1533         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1534         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1535                                     &bytes_read);
1536         if (rc) {
1537                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1538                 goto out;
1539         }
1540         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1541                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1542                                 "file version [%d] is supported by this "
1543                                 "version of eCryptfs\n",
1544                                 crypt_stat->file_version,
1545                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1546                 rc = -EINVAL;
1547                 goto out;
1548         }
1549         offset += bytes_read;
1550         if (crypt_stat->file_version >= 1) {
1551                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1552                                            &bytes_read, validate_header_size);
1553                 if (rc) {
1554                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1555                                         "metadata; rc = [%d]\n", rc);
1556                 }
1557                 offset += bytes_read;
1558         } else
1559                 set_default_header_data(crypt_stat);
1560         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1561                                        ecryptfs_dentry);
1562 out:
1563         return rc;
1564 }
1565
1566 /**
1567  * ecryptfs_read_xattr_region
1568  *
1569  * Attempts to read the crypto metadata from the extended attribute
1570  * region of the lower file.
1571  */
1572 int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry)
1573 {
1574         ssize_t size;
1575         int rc = 0;
1576
1577         size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME,
1578                                  page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1579         if (size < 0) {
1580                 printk(KERN_DEBUG "Error attempting to read the [%s] "
1581                        "xattr from the lower file; return value = [%zd]\n",
1582                        ECRYPTFS_XATTR_NAME, size);
1583                 rc = -EINVAL;
1584                 goto out;
1585         }
1586 out:
1587         return rc;
1588 }
1589
1590 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1591                                             struct dentry *ecryptfs_dentry)
1592 {
1593         int rc;
1594
1595         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry);
1596         if (rc)
1597                 goto out;
1598         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1599                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1600                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1601                 rc = -EINVAL;
1602         }
1603 out:
1604         return rc;
1605 }
1606
1607 /**
1608  * ecryptfs_read_metadata
1609  *
1610  * Common entry point for reading file metadata. From here, we could
1611  * retrieve the header information from the header region of the file,
1612  * the xattr region of the file, or some other repostory that is
1613  * stored separately from the file itself. The current implementation
1614  * supports retrieving the metadata information from the file contents
1615  * and from the xattr region.
1616  *
1617  * Returns zero if valid headers found and parsed; non-zero otherwise
1618  */
1619 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
1620                            struct file *lower_file)
1621 {
1622         int rc = 0;
1623         char *page_virt = NULL;
1624         mm_segment_t oldfs;
1625         ssize_t bytes_read;
1626         struct ecryptfs_crypt_stat *crypt_stat =
1627             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1628         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1629                 &ecryptfs_superblock_to_private(
1630                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1631
1632         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1633                                                       mount_crypt_stat);
1634         /* Read the first page from the underlying file */
1635         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1636         if (!page_virt) {
1637                 rc = -ENOMEM;
1638                 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1639                 goto out;
1640         }
1641         lower_file->f_pos = 0;
1642         oldfs = get_fs();
1643         set_fs(get_ds());
1644         bytes_read = lower_file->f_op->read(lower_file,
1645                                             (char __user *)page_virt,
1646                                             ECRYPTFS_DEFAULT_EXTENT_SIZE,
1647                                             &lower_file->f_pos);
1648         set_fs(oldfs);
1649         if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1650                 rc = -EINVAL;
1651                 goto out;
1652         }
1653         rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1654                                         ecryptfs_dentry,
1655                                         ECRYPTFS_VALIDATE_HEADER_SIZE);
1656         if (rc) {
1657                 rc = ecryptfs_read_xattr_region(page_virt,
1658                                                 ecryptfs_dentry);
1659                 if (rc) {
1660                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1661                                "file header region or xattr region\n");
1662                         rc = -EINVAL;
1663                         goto out;
1664                 }
1665                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1666                                                 ecryptfs_dentry,
1667                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1668                 if (rc) {
1669                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1670                                "file xattr region either\n");
1671                         rc = -EINVAL;
1672                 }
1673                 if (crypt_stat->mount_crypt_stat->flags
1674                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1675                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1676                 } else {
1677                         printk(KERN_WARNING "Attempt to access file with "
1678                                "crypto metadata only in the extended attribute "
1679                                "region, but eCryptfs was mounted without "
1680                                "xattr support enabled. eCryptfs will not treat "
1681                                "this like an encrypted file.\n");
1682                         rc = -EINVAL;
1683                 }
1684         }
1685 out:
1686         if (page_virt) {
1687                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1688                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1689         }
1690         return rc;
1691 }
1692
1693 /**
1694  * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1695  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1696  * @name: The plaintext name
1697  * @length: The length of the plaintext
1698  * @encoded_name: The encypted name
1699  *
1700  * Encrypts and encodes a filename into something that constitutes a
1701  * valid filename for a filesystem, with printable characters.
1702  *
1703  * We assume that we have a properly initialized crypto context,
1704  * pointed to by crypt_stat->tfm.
1705  *
1706  * TODO: Implement filename decoding and decryption here, in place of
1707  * memcpy. We are keeping the framework around for now to (1)
1708  * facilitate testing of the components needed to implement filename
1709  * encryption and (2) to provide a code base from which other
1710  * developers in the community can easily implement this feature.
1711  *
1712  * Returns the length of encoded filename; negative if error
1713  */
1714 int
1715 ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1716                          const char *name, int length, char **encoded_name)
1717 {
1718         int error = 0;
1719
1720         (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1721         if (!(*encoded_name)) {
1722                 error = -ENOMEM;
1723                 goto out;
1724         }
1725         /* TODO: Filename encryption is a scheduled feature for a
1726          * future version of eCryptfs. This function is here only for
1727          * the purpose of providing a framework for other developers
1728          * to easily implement filename encryption. Hint: Replace this
1729          * memcpy() with a call to encrypt and encode the
1730          * filename, the set the length accordingly. */
1731         memcpy((void *)(*encoded_name), (void *)name, length);
1732         (*encoded_name)[length] = '\0';
1733         error = length + 1;
1734 out:
1735         return error;
1736 }
1737
1738 /**
1739  * ecryptfs_decode_filename - converts the cipher text name to plaintext
1740  * @crypt_stat: The crypt_stat struct associated with the file
1741  * @name: The filename in cipher text
1742  * @length: The length of the cipher text name
1743  * @decrypted_name: The plaintext name
1744  *
1745  * Decodes and decrypts the filename.
1746  *
1747  * We assume that we have a properly initialized crypto context,
1748  * pointed to by crypt_stat->tfm.
1749  *
1750  * TODO: Implement filename decoding and decryption here, in place of
1751  * memcpy. We are keeping the framework around for now to (1)
1752  * facilitate testing of the components needed to implement filename
1753  * encryption and (2) to provide a code base from which other
1754  * developers in the community can easily implement this feature.
1755  *
1756  * Returns the length of decoded filename; negative if error
1757  */
1758 int
1759 ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1760                          const char *name, int length, char **decrypted_name)
1761 {
1762         int error = 0;
1763
1764         (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1765         if (!(*decrypted_name)) {
1766                 error = -ENOMEM;
1767                 goto out;
1768         }
1769         /* TODO: Filename encryption is a scheduled feature for a
1770          * future version of eCryptfs. This function is here only for
1771          * the purpose of providing a framework for other developers
1772          * to easily implement filename encryption. Hint: Replace this
1773          * memcpy() with a call to decode and decrypt the
1774          * filename, the set the length accordingly. */
1775         memcpy((void *)(*decrypted_name), (void *)name, length);
1776         (*decrypted_name)[length + 1] = '\0';   /* Only for convenience
1777                                                  * in printing out the
1778                                                  * string in debug
1779                                                  * messages */
1780         error = length;
1781 out:
1782         return error;
1783 }
1784
1785 /**
1786  * ecryptfs_process_cipher - Perform cipher initialization.
1787  * @key_tfm: Crypto context for key material, set by this function
1788  * @cipher_name: Name of the cipher
1789  * @key_size: Size of the key in bytes
1790  *
1791  * Returns zero on success. Any crypto_tfm structs allocated here
1792  * should be released by other functions, such as on a superblock put
1793  * event, regardless of whether this function succeeds for fails.
1794  */
1795 int
1796 ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
1797                         size_t *key_size)
1798 {
1799         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1800         char *full_alg_name;
1801         int rc;
1802
1803         *key_tfm = NULL;
1804         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1805                 rc = -EINVAL;
1806                 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1807                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1808                 goto out;
1809         }
1810         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1811                                                     "ecb");
1812         if (rc)
1813                 goto out;
1814         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1815         kfree(full_alg_name);
1816         if (IS_ERR(*key_tfm)) {
1817                 rc = PTR_ERR(*key_tfm);
1818                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1819                        "[%s]; rc = [%d]\n", cipher_name, rc);
1820                 goto out;
1821         }
1822         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1823         if (*key_size == 0) {
1824                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1825
1826                 *key_size = alg->max_keysize;
1827         }
1828         get_random_bytes(dummy_key, *key_size);
1829         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1830         if (rc) {
1831                 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1832                        "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
1833                 rc = -EINVAL;
1834                 goto out;
1835         }
1836 out:
1837         return rc;
1838 }