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 static 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         INIT_LIST_HEAD(&crypt_stat->keysig_list);
 208         mutex_init(&crypt_stat->keysig_list_mutex);
 209         mutex_init(&crypt_stat->cs_mutex);
 210         mutex_init(&crypt_stat->cs_tfm_mutex);
 211         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
 212         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 213 }
 214
 215 /**
 216  * ecryptfs_destroy_crypt_stat
 217  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 218  *
 219  * Releases all memory associated with a crypt_stat struct.
 220  */
 221 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 222 {
 223         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 224
 225         if (crypt_stat->tfm)
 226                 crypto_free_blkcipher(crypt_stat->tfm);
 227         if (crypt_stat->hash_tfm)
 228                 crypto_free_hash(crypt_stat->hash_tfm);
 229         mutex_lock(&crypt_stat->keysig_list_mutex);
 230         list_for_each_entry_safe(key_sig, key_sig_tmp,
 231                                  &crypt_stat->keysig_list, crypt_stat_list) {
 232                 list_del(&key_sig->crypt_stat_list);
 233                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 234         }
 235         mutex_unlock(&crypt_stat->keysig_list_mutex);
 236         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 237 }
 238
 239 void ecryptfs_destroy_mount_crypt_stat(
 240         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 241 {
 242         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 243
 244         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 245                 return;
 246         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 247         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 248                                  &mount_crypt_stat->global_auth_tok_list,
 249                                  mount_crypt_stat_list) {
 250                 list_del(&auth_tok->mount_crypt_stat_list);
 251                 mount_crypt_stat->num_global_auth_toks--;
 252                 if (auth_tok->global_auth_tok_key
 253                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 254                         key_put(auth_tok->global_auth_tok_key);
 255                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 256         }
 257         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 258         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 259 }
 260
 261 /**
 262  * virt_to_scatterlist
 263  * @addr: Virtual address
 264  * @size: Size of data; should be an even multiple of the block size
 265  * @sg: Pointer to scatterlist array; set to NULL to obtain only
 266  *      the number of scatterlist structs required in array
 267  * @sg_size: Max array size
 268  *
 269  * Fills in a scatterlist array with page references for a passed
 270  * virtual address.
 271  *
 272  * Returns the number of scatterlist structs in array used
 273  */
 274 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 275                         int sg_size)
 276 {
 277         int i = 0;
 278         struct page *pg;
 279         int offset;
 280         int remainder_of_page;
 281
 282         while (size > 0 && i < sg_size) {
 283                 pg = virt_to_page(addr);
 284                 offset = offset_in_page(addr);
 285                 if (sg) {
 286                         sg[i].page = pg;
 287                         sg[i].offset = offset;
 288                 }
 289                 remainder_of_page = PAGE_CACHE_SIZE - offset;
 290                 if (size >= remainder_of_page) {
 291                         if (sg)
 292                                 sg[i].length = remainder_of_page;
 293                         addr += remainder_of_page;
 294                         size -= remainder_of_page;
 295                 } else {
 296                         if (sg)
 297                                 sg[i].length = size;
 298                         addr += size;
 299                         size = 0;
 300                 }
 301                 i++;
 302         }
 303         if (size > 0)
 304                 return -ENOMEM;
 305         return i;
 306 }
 307
 308 /**
 309  * encrypt_scatterlist
 310  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 311  * @dest_sg: Destination of encrypted data
 312  * @src_sg: Data to be encrypted
 313  * @size: Length of data to be encrypted
 314  * @iv: iv to use during encryption
 315  *
 316  * Returns the number of bytes encrypted; negative value on error
 317  */
 318 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 319                                struct scatterlist *dest_sg,
 320                                struct scatterlist *src_sg, int size,
 321                                unsigned char *iv)
 322 {
 323         struct blkcipher_desc desc = {
 324                 .tfm = crypt_stat->tfm,
 325                 .info = iv,
 326                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 327         };
 328         int rc = 0;
 329
 330         BUG_ON(!crypt_stat || !crypt_stat->tfm
 331                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 332         if (unlikely(ecryptfs_verbosity > 0)) {
 333                 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
 334                                 crypt_stat->key_size);
 335                 ecryptfs_dump_hex(crypt_stat->key,
 336                                   crypt_stat->key_size);
 337         }
 338         /* Consider doing this once, when the file is opened */
 339         mutex_lock(&crypt_stat->cs_tfm_mutex);
 340         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 341                                      crypt_stat->key_size);
 342         if (rc) {
 343                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 344                                 rc);
 345                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 346                 rc = -EINVAL;
 347                 goto out;
 348         }
 349         ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
 350         crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
 351         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 352 out:
 353         return rc;
 354 }
 355
 356 static void
 357 ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
 358                                          int *byte_offset,
 359                                          struct ecryptfs_crypt_stat *crypt_stat,
 360                                          unsigned long extent_num)
 361 {
 362         unsigned long lower_extent_num;
 363         int extents_occupied_by_headers_at_front;
 364         int bytes_occupied_by_headers_at_front;
 365         int extent_offset;
 366         int extents_per_page;
 367
 368         bytes_occupied_by_headers_at_front =
 369                 (crypt_stat->extent_size
 370                  * crypt_stat->num_header_extents_at_front);
 371         extents_occupied_by_headers_at_front =
 372                 ( bytes_occupied_by_headers_at_front
 373                   / crypt_stat->extent_size );
 374         lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
 375         extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
 376         (*lower_page_idx) = lower_extent_num / extents_per_page;
 377         extent_offset = lower_extent_num % extents_per_page;
 378         (*byte_offset) = extent_offset * crypt_stat->extent_size;
 379         ecryptfs_printk(KERN_DEBUG, " * crypt_stat->extent_size = "
 380                         "[%d]\n", crypt_stat->extent_size);
 381         ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
 382                         "num_header_extents_at_front = [%d]\n",
 383                         crypt_stat->num_header_extents_at_front);
 384         ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
 385                         "front = [%d]\n", extents_occupied_by_headers_at_front);
 386         ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
 387                         lower_extent_num);
 388         ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
 389                         extents_per_page);
 390         ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
 391                         (*lower_page_idx));
 392         ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
 393                         extent_offset);
 394         ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
 395                         (*byte_offset));
 396 }
 397
 398 static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
 399                                    struct page *lower_page,
 400                                    struct inode *lower_inode,
 401                                    int byte_offset_in_page, int bytes_to_write)
 402 {
 403         int rc = 0;
 404
 405         if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
 406                 rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
 407                                                 ctx->param.lower_file,
 408                                                 byte_offset_in_page,
 409                                                 bytes_to_write);
 410                 if (rc) {
 411                         ecryptfs_printk(KERN_ERR, "Error calling lower "
 412                                         "commit; rc = [%d]\n", rc);
 413                         goto out;
 414                 }
 415         } else {
 416                 rc = ecryptfs_writepage_and_release_lower_page(lower_page,
 417                                                                lower_inode,
 418                                                                ctx->param.wbc);
 419                 if (rc) {
 420                         ecryptfs_printk(KERN_ERR, "Error calling lower "
 421                                         "writepage(); rc = [%d]\n", rc);
 422                         goto out;
 423                 }
 424         }
 425 out:
 426         return rc;
 427 }
 428
 429 static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
 430                                  struct page **lower_page,
 431                                  struct inode *lower_inode,
 432                                  unsigned long lower_page_idx,
 433                                  int byte_offset_in_page)
 434 {
 435         int rc = 0;
 436
 437         if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
 438                 /* TODO: Limit this to only the data extents that are
 439                  * needed */
 440                 rc = ecryptfs_get_lower_page(lower_page, lower_inode,
 441                                              ctx->param.lower_file,
 442                                              lower_page_idx,
 443                                              byte_offset_in_page,
 444                                              (PAGE_CACHE_SIZE
 445                                               - byte_offset_in_page));
 446                 if (rc) {
 447                         ecryptfs_printk(
 448                                 KERN_ERR, "Error attempting to grab, map, "
 449                                 "and prepare_write lower page with index "
 450                                 "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
 451                         goto out;
 452                 }
 453         } else {
 454                 *lower_page = grab_cache_page(lower_inode->i_mapping,
 455                                               lower_page_idx);
 456                 if (!(*lower_page)) {
 457                         rc = -EINVAL;
 458                         ecryptfs_printk(
 459                                 KERN_ERR, "Error attempting to grab and map "
 460                                 "lower page with index [0x%.16x]; rc = [%d]\n",
 461                                 lower_page_idx, rc);
 462                         goto out;
 463                 }
 464         }
 465 out:
 466         return rc;
 467 }
 468
 469 /**
 470  * ecryptfs_encrypt_page
 471  * @ctx: The context of the page
 472  *
 473  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 474  * that eCryptfs pages may straddle the lower pages -- for instance,
 475  * if the file was created on a machine with an 8K page size
 476  * (resulting in an 8K header), and then the file is copied onto a
 477  * host with a 32K page size, then when reading page 0 of the eCryptfs
 478  * file, 24K of page 0 of the lower file will be read and decrypted,
 479  * and then 8K of page 1 of the lower file will be read and decrypted.
 480  *
 481  * The actual operations performed on each page depends on the
 482  * contents of the ecryptfs_page_crypt_context struct.
 483  *
 484  * Returns zero on success; negative on error
 485  */
 486 int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
 487 {
 488         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 489         unsigned long base_extent;
 490         unsigned long extent_offset = 0;
 491         unsigned long lower_page_idx = 0;
 492         unsigned long prior_lower_page_idx = 0;
 493         struct page *lower_page;
 494         struct inode *lower_inode;
 495         struct ecryptfs_inode_info *inode_info;
 496         struct ecryptfs_crypt_stat *crypt_stat;
 497         int rc = 0;
 498         int lower_byte_offset = 0;
 499         int orig_byte_offset = 0;
 500         int num_extents_per_page;
 501 #define ECRYPTFS_PAGE_STATE_UNREAD    0
 502 #define ECRYPTFS_PAGE_STATE_READ      1
 503 #define ECRYPTFS_PAGE_STATE_MODIFIED  2
 504 #define ECRYPTFS_PAGE_STATE_WRITTEN   3
 505         int page_state;
 506
 507         lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
 508         inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
 509         crypt_stat = &inode_info->crypt_stat;
 510         if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 511                 rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
 512                                                  ctx->param.lower_file);
 513                 if (rc)
 514                         ecryptfs_printk(KERN_ERR, "Error attempting to copy "
 515                                         "page at index [0x%.16x]\n",
 516                                         ctx->page->index);
 517                 goto out;
 518         }
 519         num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
 520         base_extent = (ctx->page->index * num_extents_per_page);
 521         page_state = ECRYPTFS_PAGE_STATE_UNREAD;
 522         while (extent_offset < num_extents_per_page) {
 523                 ecryptfs_extent_to_lwr_pg_idx_and_offset(
 524                         &lower_page_idx, &lower_byte_offset, crypt_stat,
 525                         (base_extent + extent_offset));
 526                 if (prior_lower_page_idx != lower_page_idx
 527                     && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
 528                         rc = ecryptfs_write_out_page(ctx, lower_page,
 529                                                      lower_inode,
 530                                                      orig_byte_offset,
 531                                                      (PAGE_CACHE_SIZE
 532                                                       - orig_byte_offset));
 533                         if (rc) {
 534                                 ecryptfs_printk(KERN_ERR, "Error attempting "
 535                                                 "to write out page; rc = [%d]"
 536                                                 "\n", rc);
 537                                 goto out;
 538                         }
 539                         page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
 540                 }
 541                 if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
 542                     || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
 543                         rc = ecryptfs_read_in_page(ctx, &lower_page,
 544                                                    lower_inode, lower_page_idx,
 545                                                    lower_byte_offset);
 546                         if (rc) {
 547                                 ecryptfs_printk(KERN_ERR, "Error attempting "
 548                                                 "to read in lower page with "
 549                                                 "index [0x%.16x]; rc = [%d]\n",
 550                                                 lower_page_idx, rc);
 551                                 goto out;
 552                         }
 553                         orig_byte_offset = lower_byte_offset;
 554                         prior_lower_page_idx = lower_page_idx;
 555                         page_state = ECRYPTFS_PAGE_STATE_READ;
 556                 }
 557                 BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
 558                          || page_state == ECRYPTFS_PAGE_STATE_READ));
 559                 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 560                                         (base_extent + extent_offset));
 561                 if (rc) {
 562                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 563                                         "derive IV for extent [0x%.16x]; "
 564                                         "rc = [%d]\n",
 565                                         (base_extent + extent_offset), rc);
 566                         goto out;
 567                 }
 568                 if (unlikely(ecryptfs_verbosity > 0)) {
 569                         ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
 570                                         "with iv:\n");
 571                         ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
 572                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
 573                                         "encryption:\n");
 574                         ecryptfs_dump_hex((char *)
 575                                           (page_address(ctx->page)
 576                                            + (extent_offset
 577                                               * crypt_stat->extent_size)), 8);
 578                 }
 579                 rc = ecryptfs_encrypt_page_offset(
 580                         crypt_stat, lower_page, lower_byte_offset, ctx->page,
 581                         (extent_offset * crypt_stat->extent_size),
 582                         crypt_stat->extent_size, extent_iv);
 583                 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
 584                                 "rc = [%d]\n",
 585                                 (base_extent + extent_offset), rc);
 586                 if (unlikely(ecryptfs_verbosity > 0)) {
 587                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 588                                         "encryption:\n");
 589                         ecryptfs_dump_hex((char *)(page_address(lower_page)
 590                                                    + lower_byte_offset), 8);
 591                 }
 592                 page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
 593                 extent_offset++;
 594         }
 595         BUG_ON(orig_byte_offset != 0);
 596         rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
 597                                      (lower_byte_offset
 598                                       + crypt_stat->extent_size));
 599         if (rc) {
 600                 ecryptfs_printk(KERN_ERR, "Error attempting to write out "
 601                                 "page; rc = [%d]\n", rc);
 602                                 goto out;
 603         }
 604 out:
 605         return rc;
 606 }
 607
 608 /**
 609  * ecryptfs_decrypt_page
 610  * @file: The ecryptfs file
 611  * @page: The page in ecryptfs to decrypt
 612  *
 613  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 614  * that eCryptfs pages may straddle the lower pages -- for instance,
 615  * if the file was created on a machine with an 8K page size
 616  * (resulting in an 8K header), and then the file is copied onto a
 617  * host with a 32K page size, then when reading page 0 of the eCryptfs
 618  * file, 24K of page 0 of the lower file will be read and decrypted,
 619  * and then 8K of page 1 of the lower file will be read and decrypted.
 620  *
 621  * Returns zero on success; negative on error
 622  */
 623 int ecryptfs_decrypt_page(struct file *file, struct page *page)
 624 {
 625         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 626         unsigned long base_extent;
 627         unsigned long extent_offset = 0;
 628         unsigned long lower_page_idx = 0;
 629         unsigned long prior_lower_page_idx = 0;
 630         struct page *lower_page;
 631         char *lower_page_virt = NULL;
 632         struct inode *lower_inode;
 633         struct ecryptfs_crypt_stat *crypt_stat;
 634         int rc = 0;
 635         int byte_offset;
 636         int num_extents_per_page;
 637         int page_state;
 638
 639         crypt_stat = &(ecryptfs_inode_to_private(
 640                                page->mapping->host)->crypt_stat);
 641         lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
 642         if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 643                 rc = ecryptfs_do_readpage(file, page, page->index);
 644                 if (rc)
 645                         ecryptfs_printk(KERN_ERR, "Error attempting to copy "
 646                                         "page at index [0x%.16x]\n",
 647                                         page->index);
 648                 goto out;
 649         }
 650         num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
 651         base_extent = (page->index * num_extents_per_page);
 652         lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
 653                                            GFP_KERNEL);
 654         if (!lower_page_virt) {
 655                 rc = -ENOMEM;
 656                 ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
 657                                 "lower page(s)\n");
 658                 goto out;
 659         }
 660         lower_page = virt_to_page(lower_page_virt);
 661         page_state = ECRYPTFS_PAGE_STATE_UNREAD;
 662         while (extent_offset < num_extents_per_page) {
 663                 ecryptfs_extent_to_lwr_pg_idx_and_offset(
 664                         &lower_page_idx, &byte_offset, crypt_stat,
 665                         (base_extent + extent_offset));
 666                 if (prior_lower_page_idx != lower_page_idx
 667                     || page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
 668                         rc = ecryptfs_do_readpage(file, lower_page,
 669                                                   lower_page_idx);
 670                         if (rc) {
 671                                 ecryptfs_printk(KERN_ERR, "Error reading "
 672                                                 "lower encrypted page; rc = "
 673                                                 "[%d]\n", rc);
 674                                 goto out;
 675                         }
 676                         prior_lower_page_idx = lower_page_idx;
 677                         page_state = ECRYPTFS_PAGE_STATE_READ;
 678                 }
 679                 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 680                                         (base_extent + extent_offset));
 681                 if (rc) {
 682                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 683                                         "derive IV for extent [0x%.16x]; rc = "
 684                                         "[%d]\n",
 685                                         (base_extent + extent_offset), rc);
 686                         goto out;
 687                 }
 688                 if (unlikely(ecryptfs_verbosity > 0)) {
 689                         ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
 690                                         "with iv:\n");
 691                         ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
 692                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
 693                                         "decryption:\n");
 694                         ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
 695                 }
 696                 rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
 697                                                   (extent_offset
 698                                                    * crypt_stat->extent_size),
 699                                                   lower_page, byte_offset,
 700                                                   crypt_stat->extent_size,
 701                                                   extent_iv);
 702                 if (rc != crypt_stat->extent_size) {
 703                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 704                                         "decrypt extent [0x%.16x]\n",
 705                                         (base_extent + extent_offset));
 706                         goto out;
 707                 }
 708                 rc = 0;
 709                 if (unlikely(ecryptfs_verbosity > 0)) {
 710                         ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 711                                         "decryption:\n");
 712                         ecryptfs_dump_hex((char *)(page_address(page)
 713                                                    + byte_offset), 8);
 714                 }
 715                 extent_offset++;
 716         }
 717 out:
 718         if (lower_page_virt)
 719                 kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
 720         return rc;
 721 }
 722
 723 /**
 724  * decrypt_scatterlist
 725  * @crypt_stat: Cryptographic context
 726  * @dest_sg: The destination scatterlist to decrypt into
 727  * @src_sg: The source scatterlist to decrypt from
 728  * @size: The number of bytes to decrypt
 729  * @iv: The initialization vector to use for the decryption
 730  *
 731  * Returns the number of bytes decrypted; negative value on error
 732  */
 733 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 734                                struct scatterlist *dest_sg,
 735                                struct scatterlist *src_sg, int size,
 736                                unsigned char *iv)
 737 {
 738         struct blkcipher_desc desc = {
 739                 .tfm = crypt_stat->tfm,
 740                 .info = iv,
 741                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 742         };
 743         int rc = 0;
 744
 745         /* Consider doing this once, when the file is opened */
 746         mutex_lock(&crypt_stat->cs_tfm_mutex);
 747         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 748                                      crypt_stat->key_size);
 749         if (rc) {
 750                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 751                                 rc);
 752                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 753                 rc = -EINVAL;
 754                 goto out;
 755         }
 756         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
 757         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
 758         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 759         if (rc) {
 760                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
 761                                 rc);
 762                 goto out;
 763         }
 764         rc = size;
 765 out:
 766         return rc;
 767 }
 768
 769 /**
 770  * ecryptfs_encrypt_page_offset
 771  * @crypt_stat: The cryptographic context
 772  * @dst_page: The page to encrypt into
 773  * @dst_offset: The offset in the page to encrypt into
 774  * @src_page: The page to encrypt from
 775  * @src_offset: The offset in the page to encrypt from
 776  * @size: The number of bytes to encrypt
 777  * @iv: The initialization vector to use for the encryption
 778  *
 779  * Returns the number of bytes encrypted
 780  */
 781 static int
 782 ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 783                              struct page *dst_page, int dst_offset,
 784                              struct page *src_page, int src_offset, int size,
 785                              unsigned char *iv)
 786 {
 787         struct scatterlist src_sg, dst_sg;
 788
 789         src_sg.page = src_page;
 790         src_sg.offset = src_offset;
 791         src_sg.length = size;
 792         dst_sg.page = dst_page;
 793         dst_sg.offset = dst_offset;
 794         dst_sg.length = size;
 795         return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 796 }
 797
 798 /**
 799  * ecryptfs_decrypt_page_offset
 800  * @crypt_stat: The cryptographic context
 801  * @dst_page: The page to decrypt into
 802  * @dst_offset: The offset in the page to decrypt into
 803  * @src_page: The page to decrypt from
 804  * @src_offset: The offset in the page to decrypt from
 805  * @size: The number of bytes to decrypt
 806  * @iv: The initialization vector to use for the decryption
 807  *
 808  * Returns the number of bytes decrypted
 809  */
 810 static int
 811 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 812                              struct page *dst_page, int dst_offset,
 813                              struct page *src_page, int src_offset, int size,
 814                              unsigned char *iv)
 815 {
 816         struct scatterlist src_sg, dst_sg;
 817
 818         src_sg.page = src_page;
 819         src_sg.offset = src_offset;
 820         src_sg.length = size;
 821         dst_sg.page = dst_page;
 822         dst_sg.offset = dst_offset;
 823         dst_sg.length = size;
 824         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 825 }
 826
 827 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 828
 829 /**
 830  * ecryptfs_init_crypt_ctx
 831  * @crypt_stat: Uninitilized crypt stats structure
 832  *
 833  * Initialize the crypto context.
 834  *
 835  * TODO: Performance: Keep a cache of initialized cipher contexts;
 836  * only init if needed
 837  */
 838 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 839 {
 840         char *full_alg_name;
 841         int rc = -EINVAL;
 842
 843         if (!crypt_stat->cipher) {
 844                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
 845                 goto out;
 846         }
 847         ecryptfs_printk(KERN_DEBUG,
 848                         "Initializing cipher [%s]; strlen = [%d]; "
 849                         "key_size_bits = [%d]\n",
 850                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 851                         crypt_stat->key_size << 3);
 852         if (crypt_stat->tfm) {
 853                 rc = 0;
 854                 goto out;
 855         }
 856         mutex_lock(&crypt_stat->cs_tfm_mutex);
 857         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 858                                                     crypt_stat->cipher, "cbc");
 859         if (rc)
 860                 goto out;
 861         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
 862                                                  CRYPTO_ALG_ASYNC);
 863         kfree(full_alg_name);
 864         if (IS_ERR(crypt_stat->tfm)) {
 865                 rc = PTR_ERR(crypt_stat->tfm);
 866                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 867                                 "Error initializing cipher [%s]\n",
 868                                 crypt_stat->cipher);
 869                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 870                 goto out;
 871         }
 872         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 873         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 874         rc = 0;
 875 out:
 876         return rc;
 877 }
 878
 879 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 880 {
 881         int extent_size_tmp;
 882
 883         crypt_stat->extent_mask = 0xFFFFFFFF;
 884         crypt_stat->extent_shift = 0;
 885         if (crypt_stat->extent_size == 0)
 886                 return;
 887         extent_size_tmp = crypt_stat->extent_size;
 888         while ((extent_size_tmp & 0x01) == 0) {
 889                 extent_size_tmp >>= 1;
 890                 crypt_stat->extent_mask <<= 1;
 891                 crypt_stat->extent_shift++;
 892         }
 893 }
 894
 895 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 896 {
 897         /* Default values; may be overwritten as we are parsing the
 898          * packets. */
 899         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 900         set_extent_mask_and_shift(crypt_stat);
 901         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 902         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 903                 crypt_stat->num_header_extents_at_front = 0;
 904         else {
 905                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 906                         crypt_stat->num_header_extents_at_front =
 907                                 (ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE
 908                                  / crypt_stat->extent_size);
 909                 else
 910                         crypt_stat->num_header_extents_at_front =
 911                                 (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 912         }
 913 }
 914
 915 /**
 916  * ecryptfs_compute_root_iv
 917  * @crypt_stats
 918  *
 919  * On error, sets the root IV to all 0's.
 920  */
 921 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 922 {
 923         int rc = 0;
 924         char dst[MD5_DIGEST_SIZE];
 925
 926         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 927         BUG_ON(crypt_stat->iv_bytes <= 0);
 928         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 929                 rc = -EINVAL;
 930                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 931                                 "cannot generate root IV\n");
 932                 goto out;
 933         }
 934         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 935                                     crypt_stat->key_size);
 936         if (rc) {
 937                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 938                                 "MD5 while generating root IV\n");
 939                 goto out;
 940         }
 941         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 942 out:
 943         if (rc) {
 944                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 945                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 946         }
 947         return rc;
 948 }
 949
 950 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 951 {
 952         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 953         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 954         ecryptfs_compute_root_iv(crypt_stat);
 955         if (unlikely(ecryptfs_verbosity > 0)) {
 956                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 957                 ecryptfs_dump_hex(crypt_stat->key,
 958                                   crypt_stat->key_size);
 959         }
 960 }
 961
 962 /**
 963  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 964  * @crypt_stat: The inode's cryptographic context
 965  * @mount_crypt_stat: The mount point's cryptographic context
 966  *
 967  * This function propagates the mount-wide flags to individual inode
 968  * flags.
 969  */
 970 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 971         struct ecryptfs_crypt_stat *crypt_stat,
 972         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 973 {
 974         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 975                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 976         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 977                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 978 }
 979
 980 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 981         struct ecryptfs_crypt_stat *crypt_stat,
 982         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 983 {
 984         struct ecryptfs_global_auth_tok *global_auth_tok;
 985         int rc = 0;
 986
 987         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 988         list_for_each_entry(global_auth_tok,
 989                             &mount_crypt_stat->global_auth_tok_list,
 990                             mount_crypt_stat_list) {
 991                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 992                 if (rc) {
 993                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 994                         mutex_unlock(
 995                                 &mount_crypt_stat->global_auth_tok_list_mutex);
 996                         goto out;
 997                 }
 998         }
 999         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
1000 out:
1001         return rc;
1002 }
1003
1004 /**
1005  * ecryptfs_set_default_crypt_stat_vals
1006  * @crypt_stat: The inode's cryptographic context
1007  * @mount_crypt_stat: The mount point's cryptographic context
1008  *
1009  * Default values in the event that policy does not override them.
1010  */
1011 static void ecryptfs_set_default_crypt_stat_vals(
1012         struct ecryptfs_crypt_stat *crypt_stat,
1013         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1014 {
1015         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1016                                                       mount_crypt_stat);
1017         ecryptfs_set_default_sizes(crypt_stat);
1018         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
1019         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
1020         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
1021         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
1022         crypt_stat->mount_crypt_stat = mount_crypt_stat;
1023 }
1024
1025 /**
1026  * ecryptfs_new_file_context
1027  * @ecryptfs_dentry: The eCryptfs dentry
1028  *
1029  * If the crypto context for the file has not yet been established,
1030  * this is where we do that.  Establishing a new crypto context
1031  * involves the following decisions:
1032  *  - What cipher to use?
1033  *  - What set of authentication tokens to use?
1034  * Here we just worry about getting enough information into the
1035  * authentication tokens so that we know that they are available.
1036  * We associate the available authentication tokens with the new file
1037  * via the set of signatures in the crypt_stat struct.  Later, when
1038  * the headers are actually written out, we may again defer to
1039  * userspace to perform the encryption of the session key; for the
1040  * foreseeable future, this will be the case with public key packets.
1041  *
1042  * Returns zero on success; non-zero otherwise
1043  */
1044 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
1045 {
1046         struct ecryptfs_crypt_stat *crypt_stat =
1047             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1048         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1049             &ecryptfs_superblock_to_private(
1050                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
1051         int cipher_name_len;
1052         int rc = 0;
1053
1054         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
1055         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
1056         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1057                                                       mount_crypt_stat);
1058         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1059                                                          mount_crypt_stat);
1060         if (rc) {
1061                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1062                        "to the inode key sigs; rc = [%d]\n", rc);
1063                 goto out;
1064         }
1065         cipher_name_len =
1066                 strlen(mount_crypt_stat->global_default_cipher_name);
1067         memcpy(crypt_stat->cipher,
1068                mount_crypt_stat->global_default_cipher_name,
1069                cipher_name_len);
1070         crypt_stat->cipher[cipher_name_len] = '\0';
1071         crypt_stat->key_size =
1072                 mount_crypt_stat->global_default_cipher_key_size;
1073         ecryptfs_generate_new_key(crypt_stat);
1074         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1075         if (rc)
1076                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1077                                 "context for cipher [%s]: rc = [%d]\n",
1078                                 crypt_stat->cipher, rc);
1079 out:
1080         return rc;
1081 }
1082
1083 /**
1084  * contains_ecryptfs_marker - check for the ecryptfs marker
1085  * @data: The data block in which to check
1086  *
1087  * Returns one if marker found; zero if not found
1088  */
1089 static int contains_ecryptfs_marker(char *data)
1090 {
1091         u32 m_1, m_2;
1092
1093         memcpy(&m_1, data, 4);
1094         m_1 = be32_to_cpu(m_1);
1095         memcpy(&m_2, (data + 4), 4);
1096         m_2 = be32_to_cpu(m_2);
1097         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1098                 return 1;
1099         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1100                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1101                         MAGIC_ECRYPTFS_MARKER);
1102         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1103                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1104         return 0;
1105 }
1106
1107 struct ecryptfs_flag_map_elem {
1108         u32 file_flag;
1109         u32 local_flag;
1110 };
1111
1112 /* Add support for additional flags by adding elements here. */
1113 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1114         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1115         {0x00000002, ECRYPTFS_ENCRYPTED},
1116         {0x00000004, ECRYPTFS_METADATA_IN_XATTR}
1117 };
1118
1119 /**
1120  * ecryptfs_process_flags
1121  * @crypt_stat: The cryptographic context
1122  * @page_virt: Source data to be parsed
1123  * @bytes_read: Updated with the number of bytes read
1124  *
1125  * Returns zero on success; non-zero if the flag set is invalid
1126  */
1127 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1128                                   char *page_virt, int *bytes_read)
1129 {
1130         int rc = 0;
1131         int i;
1132         u32 flags;
1133
1134         memcpy(&flags, page_virt, 4);
1135         flags = be32_to_cpu(flags);
1136         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1137                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1138                 if (flags & ecryptfs_flag_map[i].file_flag) {
1139                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1140                 } else
1141                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1142         /* Version is in top 8 bits of the 32-bit flag vector */
1143         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1144         (*bytes_read) = 4;
1145         return rc;
1146 }
1147
1148 /**
1149  * write_ecryptfs_marker
1150  * @page_virt: The pointer to in a page to begin writing the marker
1151  * @written: Number of bytes written
1152  *
1153  * Marker = 0x3c81b7f5
1154  */
1155 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1156 {
1157         u32 m_1, m_2;
1158
1159         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1160         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1161         m_1 = cpu_to_be32(m_1);
1162         memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1163         m_2 = cpu_to_be32(m_2);
1164         memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1165                (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1166         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1167 }
1168
1169 static void
1170 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1171                      size_t *written)
1172 {
1173         u32 flags = 0;
1174         int i;
1175
1176         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1177                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1178                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1179                         flags |= ecryptfs_flag_map[i].file_flag;
1180         /* Version is in top 8 bits of the 32-bit flag vector */
1181         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1182         flags = cpu_to_be32(flags);
1183         memcpy(page_virt, &flags, 4);
1184         (*written) = 4;
1185 }
1186
1187 struct ecryptfs_cipher_code_str_map_elem {
1188         char cipher_str[16];
1189         u16 cipher_code;
1190 };
1191
1192 /* Add support for additional ciphers by adding elements here. The
1193  * cipher_code is whatever OpenPGP applicatoins use to identify the
1194  * ciphers. List in order of probability. */
1195 static struct ecryptfs_cipher_code_str_map_elem
1196 ecryptfs_cipher_code_str_map[] = {
1197         {"aes",RFC2440_CIPHER_AES_128 },
1198         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1199         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1200         {"cast5", RFC2440_CIPHER_CAST_5},
1201         {"twofish", RFC2440_CIPHER_TWOFISH},
1202         {"cast6", RFC2440_CIPHER_CAST_6},
1203         {"aes", RFC2440_CIPHER_AES_192},
1204         {"aes", RFC2440_CIPHER_AES_256}
1205 };
1206
1207 /**
1208  * ecryptfs_code_for_cipher_string
1209  * @crypt_stat: The cryptographic context
1210  *
1211  * Returns zero on no match, or the cipher code on match
1212  */
1213 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1214 {
1215         int i;
1216         u16 code = 0;
1217         struct ecryptfs_cipher_code_str_map_elem *map =
1218                 ecryptfs_cipher_code_str_map;
1219
1220         if (strcmp(crypt_stat->cipher, "aes") == 0) {
1221                 switch (crypt_stat->key_size) {
1222                 case 16:
1223                         code = RFC2440_CIPHER_AES_128;
1224                         break;
1225                 case 24:
1226                         code = RFC2440_CIPHER_AES_192;
1227                         break;
1228                 case 32:
1229                         code = RFC2440_CIPHER_AES_256;
1230                 }
1231         } else {
1232                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1233                         if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1234                                 code = map[i].cipher_code;
1235                                 break;
1236                         }
1237         }
1238         return code;
1239 }
1240
1241 /**
1242  * ecryptfs_cipher_code_to_string
1243  * @str: Destination to write out the cipher name
1244  * @cipher_code: The code to convert to cipher name string
1245  *
1246  * Returns zero on success
1247  */
1248 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1249 {
1250         int rc = 0;
1251         int i;
1252
1253         str[0] = '\0';
1254         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1255                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1256                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1257         if (str[0] == '\0') {
1258                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1259                                 "[%d]\n", cipher_code);
1260                 rc = -EINVAL;
1261         }
1262         return rc;
1263 }
1264
1265 /**
1266  * ecryptfs_read_header_region
1267  * @data: The virtual address to write header region data into
1268  * @dentry: The lower dentry
1269  * @mnt: The lower VFS mount
1270  *
1271  * Returns zero on success; non-zero otherwise
1272  */
1273 static int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1274                                        struct vfsmount *mnt)
1275 {
1276         struct file *lower_file;
1277         mm_segment_t oldfs;
1278         int rc;
1279
1280         rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt, O_RDONLY);
1281         if (rc) {
1282                 printk(KERN_ERR
1283                        "Error opening lower_file to read header region\n");
1284                 goto out;
1285         }
1286         lower_file->f_pos = 0;
1287         oldfs = get_fs();
1288         set_fs(get_ds());
1289         rc = lower_file->f_op->read(lower_file, (char __user *)data,
1290                               ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
1291         set_fs(oldfs);
1292         rc = ecryptfs_close_lower_file(lower_file);
1293         if (rc) {
1294                 printk(KERN_ERR "Error closing lower_file\n");
1295                 goto out;
1296         }
1297         rc = 0;
1298 out:
1299         return rc;
1300 }
1301
1302 int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
1303                                              struct vfsmount *mnt)
1304 {
1305         int rc;
1306
1307         rc = ecryptfs_read_header_region(data, dentry, mnt);
1308         if (rc)
1309                 goto out;
1310         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES))
1311                 rc = -EINVAL;
1312 out:
1313         return rc;
1314 }
1315
1316
1317 void
1318 ecryptfs_write_header_metadata(char *virt,
1319                                struct ecryptfs_crypt_stat *crypt_stat,
1320                                size_t *written)
1321 {
1322         u32 header_extent_size;
1323         u16 num_header_extents_at_front;
1324
1325         header_extent_size = (u32)crypt_stat->extent_size;
1326         num_header_extents_at_front =
1327                 (u16)crypt_stat->num_header_extents_at_front;
1328         header_extent_size = cpu_to_be32(header_extent_size);
1329         memcpy(virt, &header_extent_size, 4);
1330         virt += 4;
1331         num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1332         memcpy(virt, &num_header_extents_at_front, 2);
1333         (*written) = 6;
1334 }
1335
1336 struct kmem_cache *ecryptfs_header_cache_0;
1337 struct kmem_cache *ecryptfs_header_cache_1;
1338 struct kmem_cache *ecryptfs_header_cache_2;
1339
1340 /**
1341  * ecryptfs_write_headers_virt
1342  * @page_virt: The virtual address to write the headers to
1343  * @size: Set to the number of bytes written by this function
1344  * @crypt_stat: The cryptographic context
1345  * @ecryptfs_dentry: The eCryptfs dentry
1346  *
1347  * Format version: 1
1348  *
1349  *   Header Extent:
1350  *     Octets 0-7:        Unencrypted file size (big-endian)
1351  *     Octets 8-15:       eCryptfs special marker
1352  *     Octets 16-19:      Flags
1353  *      Octet 16:         File format version number (between 0 and 255)
1354  *      Octets 17-18:     Reserved
1355  *      Octet 19:         Bit 1 (lsb): Reserved
1356  *                        Bit 2: Encrypted?
1357  *                        Bits 3-8: Reserved
1358  *     Octets 20-23:      Header extent size (big-endian)
1359  *     Octets 24-25:      Number of header extents at front of file
1360  *                        (big-endian)
1361  *     Octet  26:         Begin RFC 2440 authentication token packet set
1362  *   Data Extent 0:
1363  *     Lower data (CBC encrypted)
1364  *   Data Extent 1:
1365  *     Lower data (CBC encrypted)
1366  *   ...
1367  *
1368  * Returns zero on success
1369  */
1370 static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
1371                                        struct ecryptfs_crypt_stat *crypt_stat,
1372                                        struct dentry *ecryptfs_dentry)
1373 {
1374         int rc;
1375         size_t written;
1376         size_t offset;
1377
1378         offset = ECRYPTFS_FILE_SIZE_BYTES;
1379         write_ecryptfs_marker((page_virt + offset), &written);
1380         offset += written;
1381         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1382         offset += written;
1383         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1384                                        &written);
1385         offset += written;
1386         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1387                                               ecryptfs_dentry, &written,
1388                                               PAGE_CACHE_SIZE - offset);
1389         if (rc)
1390                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1391                                 "set; rc = [%d]\n", rc);
1392         if (size) {
1393                 offset += written;
1394                 *size = offset;
1395         }
1396         return rc;
1397 }
1398
1399 static int
1400 ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
1401                                     struct file *lower_file, char *page_virt)
1402 {
1403         mm_segment_t oldfs;
1404         int current_header_page;
1405         int header_pages;
1406         ssize_t size;
1407         int rc = 0;
1408
1409         lower_file->f_pos = 0;
1410         oldfs = get_fs();
1411         set_fs(get_ds());
1412         size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE,
1413                          &lower_file->f_pos);
1414         if (size < 0) {
1415                 rc = (int)size;
1416                 printk(KERN_ERR "Error attempting to write lower page; "
1417                        "rc = [%d]\n", rc);
1418                 set_fs(oldfs);
1419                 goto out;
1420         }
1421         header_pages = ((crypt_stat->extent_size
1422                          * crypt_stat->num_header_extents_at_front)
1423                         / PAGE_CACHE_SIZE);
1424         memset(page_virt, 0, PAGE_CACHE_SIZE);
1425         current_header_page = 1;
1426         while (current_header_page < header_pages) {
1427                 size = vfs_write(lower_file, (char __user *)page_virt,
1428                                  PAGE_CACHE_SIZE, &lower_file->f_pos);
1429                 if (size < 0) {
1430                         rc = (int)size;
1431                         printk(KERN_ERR "Error attempting to write lower page; "
1432                                "rc = [%d]\n", rc);
1433                         set_fs(oldfs);
1434                         goto out;
1435                 }
1436                 current_header_page++;
1437         }
1438         set_fs(oldfs);
1439 out:
1440         return rc;
1441 }
1442
1443 static int
1444 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1445                                  struct ecryptfs_crypt_stat *crypt_stat,
1446                                  char *page_virt, size_t size)
1447 {
1448         int rc;
1449
1450         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1451                                size, 0);
1452         return rc;
1453 }
1454
1455 /**
1456  * ecryptfs_write_metadata
1457  * @ecryptfs_dentry: The eCryptfs dentry
1458  * @lower_file: The lower file struct, which was returned from dentry_open
1459  *
1460  * Write the file headers out.  This will likely involve a userspace
1461  * callout, in which the session key is encrypted with one or more
1462  * public keys and/or the passphrase necessary to do the encryption is
1463  * retrieved via a prompt.  Exactly what happens at this point should
1464  * be policy-dependent.
1465  *
1466  * Returns zero on success; non-zero on error
1467  */
1468 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1469                             struct file *lower_file)
1470 {
1471         struct ecryptfs_crypt_stat *crypt_stat;
1472         char *page_virt;
1473         size_t size;
1474         int rc = 0;
1475
1476         crypt_stat = &ecryptfs_inode_to_private(
1477                 ecryptfs_dentry->d_inode)->crypt_stat;
1478         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1479                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1480                         ecryptfs_printk(KERN_DEBUG, "Key is "
1481                                         "invalid; bailing out\n");
1482                         rc = -EINVAL;
1483                         goto out;
1484                 }
1485         } else {
1486                 rc = -EINVAL;
1487                 ecryptfs_printk(KERN_WARNING,
1488                                 "Called with crypt_stat->encrypted == 0\n");
1489                 goto out;
1490         }
1491         /* Released in this function */
1492         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
1493         if (!page_virt) {
1494                 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1495                 rc = -ENOMEM;
1496                 goto out;
1497         }
1498         rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
1499                                          ecryptfs_dentry);
1500         if (unlikely(rc)) {
1501                 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1502                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1503                 goto out_free;
1504         }
1505         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1506                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
1507                                                       crypt_stat, page_virt,
1508                                                       size);
1509         else
1510                 rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file,
1511                                                          page_virt);
1512         if (rc) {
1513                 printk(KERN_ERR "Error writing metadata out to lower file; "
1514                        "rc = [%d]\n", rc);
1515                 goto out_free;
1516         }
1517 out_free:
1518         kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1519 out:
1520         return rc;
1521 }
1522
1523 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1524 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1525 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1526                                  char *virt, int *bytes_read,
1527                                  int validate_header_size)
1528 {
1529         int rc = 0;
1530         u32 header_extent_size;
1531         u16 num_header_extents_at_front;
1532
1533         memcpy(&header_extent_size, virt, 4);
1534         header_extent_size = be32_to_cpu(header_extent_size);
1535         virt += 4;
1536         memcpy(&num_header_extents_at_front, virt, 2);
1537         num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1538         crypt_stat->num_header_extents_at_front =
1539                 (int)num_header_extents_at_front;
1540         (*bytes_read) = (sizeof(u32) + sizeof(u16));
1541         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1542             && ((crypt_stat->extent_size
1543                  * crypt_stat->num_header_extents_at_front)
1544                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1545                 rc = -EINVAL;
1546                 printk(KERN_WARNING "Invalid number of header extents: [%zd]\n",
1547                        crypt_stat->num_header_extents_at_front);
1548         }
1549         return rc;
1550 }
1551
1552 /**
1553  * set_default_header_data
1554  * @crypt_stat: The cryptographic context
1555  *
1556  * For version 0 file format; this function is only for backwards
1557  * compatibility for files created with the prior versions of
1558  * eCryptfs.
1559  */
1560 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1561 {
1562         crypt_stat->num_header_extents_at_front = 2;
1563 }
1564
1565 /**
1566  * ecryptfs_read_headers_virt
1567  * @page_virt: The virtual address into which to read the headers
1568  * @crypt_stat: The cryptographic context
1569  * @ecryptfs_dentry: The eCryptfs dentry
1570  * @validate_header_size: Whether to validate the header size while reading
1571  *
1572  * Read/parse the header data. The header format is detailed in the
1573  * comment block for the ecryptfs_write_headers_virt() function.
1574  *
1575  * Returns zero on success
1576  */
1577 static int ecryptfs_read_headers_virt(char *page_virt,
1578                                       struct ecryptfs_crypt_stat *crypt_stat,
1579                                       struct dentry *ecryptfs_dentry,
1580                                       int validate_header_size)
1581 {
1582         int rc = 0;
1583         int offset;
1584         int bytes_read;
1585
1586         ecryptfs_set_default_sizes(crypt_stat);
1587         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1588                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1589         offset = ECRYPTFS_FILE_SIZE_BYTES;
1590         rc = contains_ecryptfs_marker(page_virt + offset);
1591         if (rc == 0) {
1592                 rc = -EINVAL;
1593                 goto out;
1594         }
1595         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1596         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1597                                     &bytes_read);
1598         if (rc) {
1599                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1600                 goto out;
1601         }
1602         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1603                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1604                                 "file version [%d] is supported by this "
1605                                 "version of eCryptfs\n",
1606                                 crypt_stat->file_version,
1607                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1608                 rc = -EINVAL;
1609                 goto out;
1610         }
1611         offset += bytes_read;
1612         if (crypt_stat->file_version >= 1) {
1613                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1614                                            &bytes_read, validate_header_size);
1615                 if (rc) {
1616                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1617                                         "metadata; rc = [%d]\n", rc);
1618                 }
1619                 offset += bytes_read;
1620         } else
1621                 set_default_header_data(crypt_stat);
1622         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1623                                        ecryptfs_dentry);
1624 out:
1625         return rc;
1626 }
1627
1628 /**
1629  * ecryptfs_read_xattr_region
1630  * @page_virt: The vitual address into which to read the xattr data
1631  * @ecryptfs_dentry: The eCryptfs dentry
1632  *
1633  * Attempts to read the crypto metadata from the extended attribute
1634  * region of the lower file.
1635  *
1636  * Returns zero on success; non-zero on error
1637  */
1638 int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry)
1639 {
1640         ssize_t size;
1641         int rc = 0;
1642
1643         size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME,
1644                                  page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1645         if (size < 0) {
1646                 printk(KERN_DEBUG "Error attempting to read the [%s] "
1647                        "xattr from the lower file; return value = [%zd]\n",
1648                        ECRYPTFS_XATTR_NAME, size);
1649                 rc = -EINVAL;
1650                 goto out;
1651         }
1652 out:
1653         return rc;
1654 }
1655
1656 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1657                                             struct dentry *ecryptfs_dentry)
1658 {
1659         int rc;
1660
1661         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry);
1662         if (rc)
1663                 goto out;
1664         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1665                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1666                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1667                 rc = -EINVAL;
1668         }
1669 out:
1670         return rc;
1671 }
1672
1673 /**
1674  * ecryptfs_read_metadata
1675  * @ecryptfs_dentry: The eCryptfs dentry
1676  * @lower_file: The lower file from which to read the metadata
1677  *
1678  * Common entry point for reading file metadata. From here, we could
1679  * retrieve the header information from the header region of the file,
1680  * the xattr region of the file, or some other repostory that is
1681  * stored separately from the file itself. The current implementation
1682  * supports retrieving the metadata information from the file contents
1683  * and from the xattr region.
1684  *
1685  * Returns zero if valid headers found and parsed; non-zero otherwise
1686  */
1687 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
1688                            struct file *lower_file)
1689 {
1690         int rc = 0;
1691         char *page_virt = NULL;
1692         mm_segment_t oldfs;
1693         ssize_t bytes_read;
1694         struct ecryptfs_crypt_stat *crypt_stat =
1695             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1696         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1697                 &ecryptfs_superblock_to_private(
1698                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1699
1700         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1701                                                       mount_crypt_stat);
1702         /* Read the first page from the underlying file */
1703         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1704         if (!page_virt) {
1705                 rc = -ENOMEM;
1706                 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1707                 goto out;
1708         }
1709         lower_file->f_pos = 0;
1710         oldfs = get_fs();
1711         set_fs(get_ds());
1712         bytes_read = lower_file->f_op->read(lower_file,
1713                                             (char __user *)page_virt,
1714                                             ECRYPTFS_DEFAULT_EXTENT_SIZE,
1715                                             &lower_file->f_pos);
1716         set_fs(oldfs);
1717         if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1718                 rc = -EINVAL;
1719                 goto out;
1720         }
1721         rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1722                                         ecryptfs_dentry,
1723                                         ECRYPTFS_VALIDATE_HEADER_SIZE);
1724         if (rc) {
1725                 rc = ecryptfs_read_xattr_region(page_virt,
1726                                                 ecryptfs_dentry);
1727                 if (rc) {
1728                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1729                                "file header region or xattr region\n");
1730                         rc = -EINVAL;
1731                         goto out;
1732                 }
1733                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1734                                                 ecryptfs_dentry,
1735                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1736                 if (rc) {
1737                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1738                                "file xattr region either\n");
1739                         rc = -EINVAL;
1740                 }
1741                 if (crypt_stat->mount_crypt_stat->flags
1742                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1743                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1744                 } else {
1745                         printk(KERN_WARNING "Attempt to access file with "
1746                                "crypto metadata only in the extended attribute "
1747                                "region, but eCryptfs was mounted without "
1748                                "xattr support enabled. eCryptfs will not treat "
1749                                "this like an encrypted file.\n");
1750                         rc = -EINVAL;
1751                 }
1752         }
1753 out:
1754         if (page_virt) {
1755                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1756                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1757         }
1758         return rc;
1759 }
1760
1761 /**
1762  * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1763  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1764  * @name: The plaintext name
1765  * @length: The length of the plaintext
1766  * @encoded_name: The encypted name
1767  *
1768  * Encrypts and encodes a filename into something that constitutes a
1769  * valid filename for a filesystem, with printable characters.
1770  *
1771  * We assume that we have a properly initialized crypto context,
1772  * pointed to by crypt_stat->tfm.
1773  *
1774  * TODO: Implement filename decoding and decryption here, in place of
1775  * memcpy. We are keeping the framework around for now to (1)
1776  * facilitate testing of the components needed to implement filename
1777  * encryption and (2) to provide a code base from which other
1778  * developers in the community can easily implement this feature.
1779  *
1780  * Returns the length of encoded filename; negative if error
1781  */
1782 int
1783 ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1784                          const char *name, int length, char **encoded_name)
1785 {
1786         int error = 0;
1787
1788         (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1789         if (!(*encoded_name)) {
1790                 error = -ENOMEM;
1791                 goto out;
1792         }
1793         /* TODO: Filename encryption is a scheduled feature for a
1794          * future version of eCryptfs. This function is here only for
1795          * the purpose of providing a framework for other developers
1796          * to easily implement filename encryption. Hint: Replace this
1797          * memcpy() with a call to encrypt and encode the
1798          * filename, the set the length accordingly. */
1799         memcpy((void *)(*encoded_name), (void *)name, length);
1800         (*encoded_name)[length] = '\0';
1801         error = length + 1;
1802 out:
1803         return error;
1804 }
1805
1806 /**
1807  * ecryptfs_decode_filename - converts the cipher text name to plaintext
1808  * @crypt_stat: The crypt_stat struct associated with the file
1809  * @name: The filename in cipher text
1810  * @length: The length of the cipher text name
1811  * @decrypted_name: The plaintext name
1812  *
1813  * Decodes and decrypts the filename.
1814  *
1815  * We assume that we have a properly initialized crypto context,
1816  * pointed to by crypt_stat->tfm.
1817  *
1818  * TODO: Implement filename decoding and decryption here, in place of
1819  * memcpy. We are keeping the framework around for now to (1)
1820  * facilitate testing of the components needed to implement filename
1821  * encryption and (2) to provide a code base from which other
1822  * developers in the community can easily implement this feature.
1823  *
1824  * Returns the length of decoded filename; negative if error
1825  */
1826 int
1827 ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1828                          const char *name, int length, char **decrypted_name)
1829 {
1830         int error = 0;
1831
1832         (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1833         if (!(*decrypted_name)) {
1834                 error = -ENOMEM;
1835                 goto out;
1836         }
1837         /* TODO: Filename encryption is a scheduled feature for a
1838          * future version of eCryptfs. This function is here only for
1839          * the purpose of providing a framework for other developers
1840          * to easily implement filename encryption. Hint: Replace this
1841          * memcpy() with a call to decode and decrypt the
1842          * filename, the set the length accordingly. */
1843         memcpy((void *)(*decrypted_name), (void *)name, length);
1844         (*decrypted_name)[length + 1] = '\0';   /* Only for convenience
1845                                                  * in printing out the
1846                                                  * string in debug
1847                                                  * messages */
1848         error = length;
1849 out:
1850         return error;
1851 }
1852
1853 /**
1854  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1855  * @key_tfm: Crypto context for key material, set by this function
1856  * @cipher_name: Name of the cipher
1857  * @key_size: Size of the key in bytes
1858  *
1859  * Returns zero on success. Any crypto_tfm structs allocated here
1860  * should be released by other functions, such as on a superblock put
1861  * event, regardless of whether this function succeeds for fails.
1862  */
1863 static int
1864 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1865                             char *cipher_name, size_t *key_size)
1866 {
1867         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1868         char *full_alg_name;
1869         int rc;
1870
1871         *key_tfm = NULL;
1872         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1873                 rc = -EINVAL;
1874                 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1875                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1876                 goto out;
1877         }
1878         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1879                                                     "ecb");
1880         if (rc)
1881                 goto out;
1882         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1883         kfree(full_alg_name);
1884         if (IS_ERR(*key_tfm)) {
1885                 rc = PTR_ERR(*key_tfm);
1886                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1887                        "[%s]; rc = [%d]\n", cipher_name, rc);
1888                 goto out;
1889         }
1890         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1891         if (*key_size == 0) {
1892                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1893
1894                 *key_size = alg->max_keysize;
1895         }
1896         get_random_bytes(dummy_key, *key_size);
1897         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1898         if (rc) {
1899                 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1900                        "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
1901                 rc = -EINVAL;
1902                 goto out;
1903         }
1904 out:
1905         return rc;
1906 }
1907
1908 struct kmem_cache *ecryptfs_key_tfm_cache;
1909 struct list_head key_tfm_list;
1910 struct mutex key_tfm_list_mutex;
1911
1912 int ecryptfs_init_crypto(void)
1913 {
1914         mutex_init(&key_tfm_list_mutex);
1915         INIT_LIST_HEAD(&key_tfm_list);
1916         return 0;
1917 }
1918
1919 int ecryptfs_destroy_crypto(void)
1920 {
1921         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1922
1923         mutex_lock(&key_tfm_list_mutex);
1924         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1925                                  key_tfm_list) {
1926                 list_del(&key_tfm->key_tfm_list);
1927                 if (key_tfm->key_tfm)
1928                         crypto_free_blkcipher(key_tfm->key_tfm);
1929                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1930         }
1931         mutex_unlock(&key_tfm_list_mutex);
1932         return 0;
1933 }
1934
1935 int
1936 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1937                          size_t key_size)
1938 {
1939         struct ecryptfs_key_tfm *tmp_tfm;
1940         int rc = 0;
1941
1942         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1943         if (key_tfm != NULL)
1944                 (*key_tfm) = tmp_tfm;
1945         if (!tmp_tfm) {
1946                 rc = -ENOMEM;
1947                 printk(KERN_ERR "Error attempting to allocate from "
1948                        "ecryptfs_key_tfm_cache\n");
1949                 goto out;
1950         }
1951         mutex_init(&tmp_tfm->key_tfm_mutex);
1952         strncpy(tmp_tfm->cipher_name, cipher_name,
1953                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1954         tmp_tfm->key_size = key_size;
1955         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1956                                          tmp_tfm->cipher_name,
1957                                          &tmp_tfm->key_size);
1958         if (rc) {
1959                 printk(KERN_ERR "Error attempting to initialize key TFM "
1960                        "cipher with name = [%s]; rc = [%d]\n",
1961                        tmp_tfm->cipher_name, rc);
1962                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1963                 if (key_tfm != NULL)
1964                         (*key_tfm) = NULL;
1965                 goto out;
1966         }
1967         mutex_lock(&key_tfm_list_mutex);
1968         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1969         mutex_unlock(&key_tfm_list_mutex);
1970 out:
1971         return rc;
1972 }
1973
1974 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1975                                                struct mutex **tfm_mutex,
1976                                                char *cipher_name)
1977 {
1978         struct ecryptfs_key_tfm *key_tfm;
1979         int rc = 0;
1980
1981         (*tfm) = NULL;
1982         (*tfm_mutex) = NULL;
1983         mutex_lock(&key_tfm_list_mutex);
1984         list_for_each_entry(key_tfm, &key_tfm_list, key_tfm_list) {
1985                 if (strcmp(key_tfm->cipher_name, cipher_name) == 0) {
1986                         (*tfm) = key_tfm->key_tfm;
1987                         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1988                         mutex_unlock(&key_tfm_list_mutex);
1989                         goto out;
1990                 }
1991         }
1992         mutex_unlock(&key_tfm_list_mutex);
1993         rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1994         if (rc) {
1995                 printk(KERN_ERR "Error adding new key_tfm to list; rc = [%d]\n",
1996                        rc);
1997                 goto out;
1998         }
1999         (*tfm) = key_tfm->key_tfm;
2000         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
2001 out:
2002         return rc;
2003 }