git.oblomov.eu Git - linux-2.6/blob - 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         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_destruct_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_destruct_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_destruct_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->header_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->header_extent_size = "
 380                         "[%d]\n", crypt_stat->header_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  *
 726  * Returns the number of bytes decrypted; negative value on error
 727  */
 728 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 729                                struct scatterlist *dest_sg,
 730                                struct scatterlist *src_sg, int size,
 731                                unsigned char *iv)
 732 {
 733         struct blkcipher_desc desc = {
 734                 .tfm = crypt_stat->tfm,
 735                 .info = iv,
 736                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
 737         };
 738         int rc = 0;
 739
 740         /* Consider doing this once, when the file is opened */
 741         mutex_lock(&crypt_stat->cs_tfm_mutex);
 742         rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 743                                      crypt_stat->key_size);
 744         if (rc) {
 745                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
 746                                 rc);
 747                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 748                 rc = -EINVAL;
 749                 goto out;
 750         }
 751         ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
 752         rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
 753         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 754         if (rc) {
 755                 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
 756                                 rc);
 757                 goto out;
 758         }
 759         rc = size;
 760 out:
 761         return rc;
 762 }
 763
 764 /**
 765  * ecryptfs_encrypt_page_offset
 766  *
 767  * Returns the number of bytes encrypted
 768  */
 769 static int
 770 ecryptfs_encrypt_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 encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 784 }
 785
 786 /**
 787  * ecryptfs_decrypt_page_offset
 788  *
 789  * Returns the number of bytes decrypted
 790  */
 791 static int
 792 ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
 793                              struct page *dst_page, int dst_offset,
 794                              struct page *src_page, int src_offset, int size,
 795                              unsigned char *iv)
 796 {
 797         struct scatterlist src_sg, dst_sg;
 798
 799         src_sg.page = src_page;
 800         src_sg.offset = src_offset;
 801         src_sg.length = size;
 802         dst_sg.page = dst_page;
 803         dst_sg.offset = dst_offset;
 804         dst_sg.length = size;
 805         return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
 806 }
 807
 808 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 809
 810 /**
 811  * ecryptfs_init_crypt_ctx
 812  * @crypt_stat: Uninitilized crypt stats structure
 813  *
 814  * Initialize the crypto context.
 815  *
 816  * TODO: Performance: Keep a cache of initialized cipher contexts;
 817  * only init if needed
 818  */
 819 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 820 {
 821         char *full_alg_name;
 822         int rc = -EINVAL;
 823
 824         if (!crypt_stat->cipher) {
 825                 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
 826                 goto out;
 827         }
 828         ecryptfs_printk(KERN_DEBUG,
 829                         "Initializing cipher [%s]; strlen = [%d]; "
 830                         "key_size_bits = [%d]\n",
 831                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 832                         crypt_stat->key_size << 3);
 833         if (crypt_stat->tfm) {
 834                 rc = 0;
 835                 goto out;
 836         }
 837         mutex_lock(&crypt_stat->cs_tfm_mutex);
 838         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 839                                                     crypt_stat->cipher, "cbc");
 840         if (rc)
 841                 goto out;
 842         crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
 843                                                  CRYPTO_ALG_ASYNC);
 844         kfree(full_alg_name);
 845         if (IS_ERR(crypt_stat->tfm)) {
 846                 rc = PTR_ERR(crypt_stat->tfm);
 847                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 848                                 "Error initializing cipher [%s]\n",
 849                                 crypt_stat->cipher);
 850                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 851                 goto out;
 852         }
 853         crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 854         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 855         rc = 0;
 856 out:
 857         return rc;
 858 }
 859
 860 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 861 {
 862         int extent_size_tmp;
 863
 864         crypt_stat->extent_mask = 0xFFFFFFFF;
 865         crypt_stat->extent_shift = 0;
 866         if (crypt_stat->extent_size == 0)
 867                 return;
 868         extent_size_tmp = crypt_stat->extent_size;
 869         while ((extent_size_tmp & 0x01) == 0) {
 870                 extent_size_tmp >>= 1;
 871                 crypt_stat->extent_mask <<= 1;
 872                 crypt_stat->extent_shift++;
 873         }
 874 }
 875
 876 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 877 {
 878         /* Default values; may be overwritten as we are parsing the
 879          * packets. */
 880         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 881         set_extent_mask_and_shift(crypt_stat);
 882         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 883         if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
 884                 crypt_stat->header_extent_size =
 885                         ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 886         } else
 887                 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
 888         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 889                 crypt_stat->num_header_extents_at_front = 0;
 890         else
 891                 crypt_stat->num_header_extents_at_front = 1;
 892 }
 893
 894 /**
 895  * ecryptfs_compute_root_iv
 896  * @crypt_stats
 897  *
 898  * On error, sets the root IV to all 0's.
 899  */
 900 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 901 {
 902         int rc = 0;
 903         char dst[MD5_DIGEST_SIZE];
 904
 905         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 906         BUG_ON(crypt_stat->iv_bytes <= 0);
 907         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 908                 rc = -EINVAL;
 909                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 910                                 "cannot generate root IV\n");
 911                 goto out;
 912         }
 913         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 914                                     crypt_stat->key_size);
 915         if (rc) {
 916                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 917                                 "MD5 while generating root IV\n");
 918                 goto out;
 919         }
 920         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 921 out:
 922         if (rc) {
 923                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 924                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 925         }
 926         return rc;
 927 }
 928
 929 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 930 {
 931         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 932         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 933         ecryptfs_compute_root_iv(crypt_stat);
 934         if (unlikely(ecryptfs_verbosity > 0)) {
 935                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 936                 ecryptfs_dump_hex(crypt_stat->key,
 937                                   crypt_stat->key_size);
 938         }
 939 }
 940
 941 /**
 942  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 943  *
 944  * This function propagates the mount-wide flags to individual inode
 945  * flags.
 946  */
 947 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 948         struct ecryptfs_crypt_stat *crypt_stat,
 949         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 950 {
 951         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 952                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 953         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 954                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 955 }
 956
 957 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 958         struct ecryptfs_crypt_stat *crypt_stat,
 959         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 960 {
 961         struct ecryptfs_global_auth_tok *global_auth_tok;
 962         int rc = 0;
 963
 964         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 965         list_for_each_entry(global_auth_tok,
 966                             &mount_crypt_stat->global_auth_tok_list,
 967                             mount_crypt_stat_list) {
 968                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 969                 if (rc) {
 970                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 971                         mutex_unlock(
 972                                 &mount_crypt_stat->global_auth_tok_list_mutex);
 973                         goto out;
 974                 }
 975         }
 976         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 977 out:
 978         return rc;
 979 }
 980
 981 /**
 982  * ecryptfs_set_default_crypt_stat_vals
 983  * @crypt_stat
 984  *
 985  * Default values in the event that policy does not override them.
 986  */
 987 static void ecryptfs_set_default_crypt_stat_vals(
 988         struct ecryptfs_crypt_stat *crypt_stat,
 989         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 990 {
 991         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 992                                                       mount_crypt_stat);
 993         ecryptfs_set_default_sizes(crypt_stat);
 994         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 995         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 996         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 997         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 998         crypt_stat->mount_crypt_stat = mount_crypt_stat;
 999 }
1000
1001 /**
1002  * ecryptfs_new_file_context
1003  * @ecryptfs_dentry
1004  *
1005  * If the crypto context for the file has not yet been established,
1006  * this is where we do that.  Establishing a new crypto context
1007  * involves the following decisions:
1008  *  - What cipher to use?
1009  *  - What set of authentication tokens to use?
1010  * Here we just worry about getting enough information into the
1011  * authentication tokens so that we know that they are available.
1012  * We associate the available authentication tokens with the new file
1013  * via the set of signatures in the crypt_stat struct.  Later, when
1014  * the headers are actually written out, we may again defer to
1015  * userspace to perform the encryption of the session key; for the
1016  * foreseeable future, this will be the case with public key packets.
1017  *
1018  * Returns zero on success; non-zero otherwise
1019  */
1020 /* Associate an authentication token(s) with the file */
1021 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
1022 {
1023         struct ecryptfs_crypt_stat *crypt_stat =
1024             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1025         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1026             &ecryptfs_superblock_to_private(
1027                     ecryptfs_dentry->d_sb)->mount_crypt_stat;
1028         int cipher_name_len;
1029         int rc = 0;
1030
1031         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
1032         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1033         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1034         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1035                                                       mount_crypt_stat);
1036         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
1037                                                          mount_crypt_stat);
1038         if (rc) {
1039                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
1040                        "to the inode key sigs; rc = [%d]\n", rc);
1041                 goto out;
1042         }
1043         cipher_name_len =
1044                 strlen(mount_crypt_stat->global_default_cipher_name);
1045         memcpy(crypt_stat->cipher,
1046                mount_crypt_stat->global_default_cipher_name,
1047                cipher_name_len);
1048         crypt_stat->cipher[cipher_name_len] = '\0';
1049         crypt_stat->key_size =
1050                 mount_crypt_stat->global_default_cipher_key_size;
1051         ecryptfs_generate_new_key(crypt_stat);
1052         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1053         if (rc)
1054                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1055                                 "context for cipher [%s]: rc = [%d]\n",
1056                                 crypt_stat->cipher, rc);
1057 out:
1058         return rc;
1059 }
1060
1061 /**
1062  * contains_ecryptfs_marker - check for the ecryptfs marker
1063  * @data: The data block in which to check
1064  *
1065  * Returns one if marker found; zero if not found
1066  */
1067 static int contains_ecryptfs_marker(char *data)
1068 {
1069         u32 m_1, m_2;
1070
1071         memcpy(&m_1, data, 4);
1072         m_1 = be32_to_cpu(m_1);
1073         memcpy(&m_2, (data + 4), 4);
1074         m_2 = be32_to_cpu(m_2);
1075         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1076                 return 1;
1077         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1078                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1079                         MAGIC_ECRYPTFS_MARKER);
1080         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1081                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1082         return 0;
1083 }
1084
1085 struct ecryptfs_flag_map_elem {
1086         u32 file_flag;
1087         u32 local_flag;
1088 };
1089
1090 /* Add support for additional flags by adding elements here. */
1091 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1092         {0x00000001, ECRYPTFS_ENABLE_HMAC},
1093         {0x00000002, ECRYPTFS_ENCRYPTED},
1094         {0x00000004, ECRYPTFS_METADATA_IN_XATTR}
1095 };
1096
1097 /**
1098  * ecryptfs_process_flags
1099  * @crypt_stat
1100  * @page_virt: Source data to be parsed
1101  * @bytes_read: Updated with the number of bytes read
1102  *
1103  * Returns zero on success; non-zero if the flag set is invalid
1104  */
1105 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1106                                   char *page_virt, int *bytes_read)
1107 {
1108         int rc = 0;
1109         int i;
1110         u32 flags;
1111
1112         memcpy(&flags, page_virt, 4);
1113         flags = be32_to_cpu(flags);
1114         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1115                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1116                 if (flags & ecryptfs_flag_map[i].file_flag) {
1117                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
1118                 } else
1119                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
1120         /* Version is in top 8 bits of the 32-bit flag vector */
1121         crypt_stat->file_version = ((flags >> 24) & 0xFF);
1122         (*bytes_read) = 4;
1123         return rc;
1124 }
1125
1126 /**
1127  * write_ecryptfs_marker
1128  * @page_virt: The pointer to in a page to begin writing the marker
1129  * @written: Number of bytes written
1130  *
1131  * Marker = 0x3c81b7f5
1132  */
1133 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1134 {
1135         u32 m_1, m_2;
1136
1137         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1138         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1139         m_1 = cpu_to_be32(m_1);
1140         memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1141         m_2 = cpu_to_be32(m_2);
1142         memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1143                (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1144         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1145 }
1146
1147 static void
1148 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1149                      size_t *written)
1150 {
1151         u32 flags = 0;
1152         int i;
1153
1154         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1155                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
1156                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
1157                         flags |= ecryptfs_flag_map[i].file_flag;
1158         /* Version is in top 8 bits of the 32-bit flag vector */
1159         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1160         flags = cpu_to_be32(flags);
1161         memcpy(page_virt, &flags, 4);
1162         (*written) = 4;
1163 }
1164
1165 struct ecryptfs_cipher_code_str_map_elem {
1166         char cipher_str[16];
1167         u16 cipher_code;
1168 };
1169
1170 /* Add support for additional ciphers by adding elements here. The
1171  * cipher_code is whatever OpenPGP applicatoins use to identify the
1172  * ciphers. List in order of probability. */
1173 static struct ecryptfs_cipher_code_str_map_elem
1174 ecryptfs_cipher_code_str_map[] = {
1175         {"aes",RFC2440_CIPHER_AES_128 },
1176         {"blowfish", RFC2440_CIPHER_BLOWFISH},
1177         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1178         {"cast5", RFC2440_CIPHER_CAST_5},
1179         {"twofish", RFC2440_CIPHER_TWOFISH},
1180         {"cast6", RFC2440_CIPHER_CAST_6},
1181         {"aes", RFC2440_CIPHER_AES_192},
1182         {"aes", RFC2440_CIPHER_AES_256}
1183 };
1184
1185 /**
1186  * ecryptfs_code_for_cipher_string
1187  * @str: The string representing the cipher name
1188  *
1189  * Returns zero on no match, or the cipher code on match
1190  */
1191 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1192 {
1193         int i;
1194         u16 code = 0;
1195         struct ecryptfs_cipher_code_str_map_elem *map =
1196                 ecryptfs_cipher_code_str_map;
1197
1198         if (strcmp(crypt_stat->cipher, "aes") == 0) {
1199                 switch (crypt_stat->key_size) {
1200                 case 16:
1201                         code = RFC2440_CIPHER_AES_128;
1202                         break;
1203                 case 24:
1204                         code = RFC2440_CIPHER_AES_192;
1205                         break;
1206                 case 32:
1207                         code = RFC2440_CIPHER_AES_256;
1208                 }
1209         } else {
1210                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1211                         if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1212                                 code = map[i].cipher_code;
1213                                 break;
1214                         }
1215         }
1216         return code;
1217 }
1218
1219 /**
1220  * ecryptfs_cipher_code_to_string
1221  * @str: Destination to write out the cipher name
1222  * @cipher_code: The code to convert to cipher name string
1223  *
1224  * Returns zero on success
1225  */
1226 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1227 {
1228         int rc = 0;
1229         int i;
1230
1231         str[0] = '\0';
1232         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1233                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1234                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1235         if (str[0] == '\0') {
1236                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1237                                 "[%d]\n", cipher_code);
1238                 rc = -EINVAL;
1239         }
1240         return rc;
1241 }
1242
1243 /**
1244  * ecryptfs_read_header_region
1245  * @data
1246  * @dentry
1247  * @nd
1248  *
1249  * Returns zero on success; non-zero otherwise
1250  */
1251 static int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1252                                        struct vfsmount *mnt)
1253 {
1254         struct file *lower_file;
1255         mm_segment_t oldfs;
1256         int rc;
1257
1258         if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
1259                                            O_RDONLY))) {
1260                 printk(KERN_ERR
1261                        "Error opening lower_file to read header region\n");
1262                 goto out;
1263         }
1264         lower_file->f_pos = 0;
1265         oldfs = get_fs();
1266         set_fs(get_ds());
1267         rc = lower_file->f_op->read(lower_file, (char __user *)data,
1268                               ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
1269         set_fs(oldfs);
1270         if ((rc = ecryptfs_close_lower_file(lower_file))) {
1271                 printk(KERN_ERR "Error closing lower_file\n");
1272                 goto out;
1273         }
1274         rc = 0;
1275 out:
1276         return rc;
1277 }
1278
1279 int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
1280                                              struct vfsmount *mnt)
1281 {
1282         int rc;
1283
1284         rc = ecryptfs_read_header_region(data, dentry, mnt);
1285         if (rc)
1286                 goto out;
1287         if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES))
1288                 rc = -EINVAL;
1289 out:
1290         return rc;
1291 }
1292
1293
1294 void
1295 ecryptfs_write_header_metadata(char *virt,
1296                                struct ecryptfs_crypt_stat *crypt_stat,
1297                                size_t *written)
1298 {
1299         u32 header_extent_size;
1300         u16 num_header_extents_at_front;
1301
1302         header_extent_size = (u32)crypt_stat->header_extent_size;
1303         num_header_extents_at_front =
1304                 (u16)crypt_stat->num_header_extents_at_front;
1305         header_extent_size = cpu_to_be32(header_extent_size);
1306         memcpy(virt, &header_extent_size, 4);
1307         virt += 4;
1308         num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1309         memcpy(virt, &num_header_extents_at_front, 2);
1310         (*written) = 6;
1311 }
1312
1313 struct kmem_cache *ecryptfs_header_cache_0;
1314 struct kmem_cache *ecryptfs_header_cache_1;
1315 struct kmem_cache *ecryptfs_header_cache_2;
1316
1317 /**
1318  * ecryptfs_write_headers_virt
1319  * @page_virt
1320  * @crypt_stat
1321  * @ecryptfs_dentry
1322  *
1323  * Format version: 1
1324  *
1325  *   Header Extent:
1326  *     Octets 0-7:        Unencrypted file size (big-endian)
1327  *     Octets 8-15:       eCryptfs special marker
1328  *     Octets 16-19:      Flags
1329  *      Octet 16:         File format version number (between 0 and 255)
1330  *      Octets 17-18:     Reserved
1331  *      Octet 19:         Bit 1 (lsb): Reserved
1332  *                        Bit 2: Encrypted?
1333  *                        Bits 3-8: Reserved
1334  *     Octets 20-23:      Header extent size (big-endian)
1335  *     Octets 24-25:      Number of header extents at front of file
1336  *                        (big-endian)
1337  *     Octet  26:         Begin RFC 2440 authentication token packet set
1338  *   Data Extent 0:
1339  *     Lower data (CBC encrypted)
1340  *   Data Extent 1:
1341  *     Lower data (CBC encrypted)
1342  *   ...
1343  *
1344  * Returns zero on success
1345  */
1346 static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
1347                                        struct ecryptfs_crypt_stat *crypt_stat,
1348                                        struct dentry *ecryptfs_dentry)
1349 {
1350         int rc;
1351         size_t written;
1352         size_t offset;
1353
1354         offset = ECRYPTFS_FILE_SIZE_BYTES;
1355         write_ecryptfs_marker((page_virt + offset), &written);
1356         offset += written;
1357         write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1358         offset += written;
1359         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1360                                        &written);
1361         offset += written;
1362         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1363                                               ecryptfs_dentry, &written,
1364                                               PAGE_CACHE_SIZE - offset);
1365         if (rc)
1366                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1367                                 "set; rc = [%d]\n", rc);
1368         if (size) {
1369                 offset += written;
1370                 *size = offset;
1371         }
1372         return rc;
1373 }
1374
1375 static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
1376                                                struct file *lower_file,
1377                                                char *page_virt)
1378 {
1379         mm_segment_t oldfs;
1380         int current_header_page;
1381         int header_pages;
1382         ssize_t size;
1383         int rc = 0;
1384
1385         lower_file->f_pos = 0;
1386         oldfs = get_fs();
1387         set_fs(get_ds());
1388         size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE,
1389                          &lower_file->f_pos);
1390         if (size < 0) {
1391                 rc = (int)size;
1392                 printk(KERN_ERR "Error attempting to write lower page; "
1393                        "rc = [%d]\n", rc);
1394                 set_fs(oldfs);
1395                 goto out;
1396         }
1397         header_pages = ((crypt_stat->header_extent_size
1398                          * crypt_stat->num_header_extents_at_front)
1399                         / PAGE_CACHE_SIZE);
1400         memset(page_virt, 0, PAGE_CACHE_SIZE);
1401         current_header_page = 1;
1402         while (current_header_page < header_pages) {
1403                 size = vfs_write(lower_file, (char __user *)page_virt,
1404                                  PAGE_CACHE_SIZE, &lower_file->f_pos);
1405                 if (size < 0) {
1406                         rc = (int)size;
1407                         printk(KERN_ERR "Error attempting to write lower page; "
1408                                "rc = [%d]\n", rc);
1409                         set_fs(oldfs);
1410                         goto out;
1411                 }
1412                 current_header_page++;
1413         }
1414         set_fs(oldfs);
1415 out:
1416         return rc;
1417 }
1418
1419 static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1420                                             struct ecryptfs_crypt_stat *crypt_stat,
1421                                             char *page_virt, size_t size)
1422 {
1423         int rc;
1424
1425         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1426                                size, 0);
1427         return rc;
1428 }
1429
1430 /**
1431  * ecryptfs_write_metadata
1432  * @lower_file: The lower file struct, which was returned from dentry_open
1433  *
1434  * Write the file headers out.  This will likely involve a userspace
1435  * callout, in which the session key is encrypted with one or more
1436  * public keys and/or the passphrase necessary to do the encryption is
1437  * retrieved via a prompt.  Exactly what happens at this point should
1438  * be policy-dependent.
1439  *
1440  * Returns zero on success; non-zero on error
1441  */
1442 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1443                             struct file *lower_file)
1444 {
1445         struct ecryptfs_crypt_stat *crypt_stat;
1446         char *page_virt;
1447         size_t size;
1448         int rc = 0;
1449
1450         crypt_stat = &ecryptfs_inode_to_private(
1451                 ecryptfs_dentry->d_inode)->crypt_stat;
1452         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1453                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1454                         ecryptfs_printk(KERN_DEBUG, "Key is "
1455                                         "invalid; bailing out\n");
1456                         rc = -EINVAL;
1457                         goto out;
1458                 }
1459         } else {
1460                 rc = -EINVAL;
1461                 ecryptfs_printk(KERN_WARNING,
1462                                 "Called with crypt_stat->encrypted == 0\n");
1463                 goto out;
1464         }
1465         /* Released in this function */
1466         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
1467         if (!page_virt) {
1468                 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1469                 rc = -ENOMEM;
1470                 goto out;
1471         }
1472         rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
1473                                          ecryptfs_dentry);
1474         if (unlikely(rc)) {
1475                 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1476                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1477                 goto out_free;
1478         }
1479         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1480                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
1481                                                       crypt_stat, page_virt,
1482                                                       size);
1483         else
1484                 rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file,
1485                                                          page_virt);
1486         if (rc) {
1487                 printk(KERN_ERR "Error writing metadata out to lower file; "
1488                        "rc = [%d]\n", rc);
1489                 goto out_free;
1490         }
1491 out_free:
1492         kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1493 out:
1494         return rc;
1495 }
1496
1497 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1498 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1499 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1500                                  char *virt, int *bytes_read,
1501                                  int validate_header_size)
1502 {
1503         int rc = 0;
1504         u32 header_extent_size;
1505         u16 num_header_extents_at_front;
1506
1507         memcpy(&header_extent_size, virt, 4);
1508         header_extent_size = be32_to_cpu(header_extent_size);
1509         virt += 4;
1510         memcpy(&num_header_extents_at_front, virt, 2);
1511         num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1512         crypt_stat->header_extent_size = (int)header_extent_size;
1513         crypt_stat->num_header_extents_at_front =
1514                 (int)num_header_extents_at_front;
1515         (*bytes_read) = 6;
1516         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1517             && ((crypt_stat->header_extent_size
1518                  * crypt_stat->num_header_extents_at_front)
1519                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1520                 rc = -EINVAL;
1521                 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1522                                 "[%d]\n", crypt_stat->header_extent_size);
1523         }
1524         return rc;
1525 }
1526
1527 /**
1528  * set_default_header_data
1529  *
1530  * For version 0 file format; this function is only for backwards
1531  * compatibility for files created with the prior versions of
1532  * eCryptfs.
1533  */
1534 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1535 {
1536         crypt_stat->header_extent_size = 4096;
1537         crypt_stat->num_header_extents_at_front = 1;
1538 }
1539
1540 /**
1541  * ecryptfs_read_headers_virt
1542  *
1543  * Read/parse the header data. The header format is detailed in the
1544  * comment block for the ecryptfs_write_headers_virt() function.
1545  *
1546  * Returns zero on success
1547  */
1548 static int ecryptfs_read_headers_virt(char *page_virt,
1549                                       struct ecryptfs_crypt_stat *crypt_stat,
1550                                       struct dentry *ecryptfs_dentry,
1551                                       int validate_header_size)
1552 {
1553         int rc = 0;
1554         int offset;
1555         int bytes_read;
1556
1557         ecryptfs_set_default_sizes(crypt_stat);
1558         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1559                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1560         offset = ECRYPTFS_FILE_SIZE_BYTES;
1561         rc = contains_ecryptfs_marker(page_virt + offset);
1562         if (rc == 0) {
1563                 rc = -EINVAL;
1564                 goto out;
1565         }
1566         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1567         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1568                                     &bytes_read);
1569         if (rc) {
1570                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1571                 goto out;
1572         }
1573         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1574                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1575                                 "file version [%d] is supported by this "
1576                                 "version of eCryptfs\n",
1577                                 crypt_stat->file_version,
1578                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1579                 rc = -EINVAL;
1580                 goto out;
1581         }
1582         offset += bytes_read;
1583         if (crypt_stat->file_version >= 1) {
1584                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1585                                            &bytes_read, validate_header_size);
1586                 if (rc) {
1587                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1588                                         "metadata; rc = [%d]\n", rc);
1589                 }
1590                 offset += bytes_read;
1591         } else
1592                 set_default_header_data(crypt_stat);
1593         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1594                                        ecryptfs_dentry);
1595 out:
1596         return rc;
1597 }
1598
1599 /**
1600  * ecryptfs_read_xattr_region
1601  *
1602  * Attempts to read the crypto metadata from the extended attribute
1603  * region of the lower file.
1604  */
1605 int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry)
1606 {
1607         ssize_t size;
1608         int rc = 0;
1609
1610         size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME,
1611                                  page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1612         if (size < 0) {
1613                 printk(KERN_DEBUG "Error attempting to read the [%s] "
1614                        "xattr from the lower file; return value = [%zd]\n",
1615                        ECRYPTFS_XATTR_NAME, size);
1616                 rc = -EINVAL;
1617                 goto out;
1618         }
1619 out:
1620         return rc;
1621 }
1622
1623 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1624                                             struct dentry *ecryptfs_dentry)
1625 {
1626         int rc;
1627
1628         rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry);
1629         if (rc)
1630                 goto out;
1631         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1632                 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1633                         "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1634                 rc = -EINVAL;
1635         }
1636 out:
1637         return rc;
1638 }
1639
1640 /**
1641  * ecryptfs_read_metadata
1642  *
1643  * Common entry point for reading file metadata. From here, we could
1644  * retrieve the header information from the header region of the file,
1645  * the xattr region of the file, or some other repostory that is
1646  * stored separately from the file itself. The current implementation
1647  * supports retrieving the metadata information from the file contents
1648  * and from the xattr region.
1649  *
1650  * Returns zero if valid headers found and parsed; non-zero otherwise
1651  */
1652 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
1653                            struct file *lower_file)
1654 {
1655         int rc = 0;
1656         char *page_virt = NULL;
1657         mm_segment_t oldfs;
1658         ssize_t bytes_read;
1659         struct ecryptfs_crypt_stat *crypt_stat =
1660             &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1661         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1662                 &ecryptfs_superblock_to_private(
1663                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1664
1665         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1666                                                       mount_crypt_stat);
1667         /* Read the first page from the underlying file */
1668         page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1669         if (!page_virt) {
1670                 rc = -ENOMEM;
1671                 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1672                 goto out;
1673         }
1674         lower_file->f_pos = 0;
1675         oldfs = get_fs();
1676         set_fs(get_ds());
1677         bytes_read = lower_file->f_op->read(lower_file,
1678                                             (char __user *)page_virt,
1679                                             ECRYPTFS_DEFAULT_EXTENT_SIZE,
1680                                             &lower_file->f_pos);
1681         set_fs(oldfs);
1682         if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1683                 rc = -EINVAL;
1684                 goto out;
1685         }
1686         rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1687                                         ecryptfs_dentry,
1688                                         ECRYPTFS_VALIDATE_HEADER_SIZE);
1689         if (rc) {
1690                 rc = ecryptfs_read_xattr_region(page_virt,
1691                                                 ecryptfs_dentry);
1692                 if (rc) {
1693                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1694                                "file header region or xattr region\n");
1695                         rc = -EINVAL;
1696                         goto out;
1697                 }
1698                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1699                                                 ecryptfs_dentry,
1700                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1701                 if (rc) {
1702                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1703                                "file xattr region either\n");
1704                         rc = -EINVAL;
1705                 }
1706                 if (crypt_stat->mount_crypt_stat->flags
1707                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1708                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1709                 } else {
1710                         printk(KERN_WARNING "Attempt to access file with "
1711                                "crypto metadata only in the extended attribute "
1712                                "region, but eCryptfs was mounted without "
1713                                "xattr support enabled. eCryptfs will not treat "
1714                                "this like an encrypted file.\n");
1715                         rc = -EINVAL;
1716                 }
1717         }
1718 out:
1719         if (page_virt) {
1720                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1721                 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1722         }
1723         return rc;
1724 }
1725
1726 /**
1727  * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1728  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1729  * @name: The plaintext name
1730  * @length: The length of the plaintext
1731  * @encoded_name: The encypted name
1732  *
1733  * Encrypts and encodes a filename into something that constitutes a
1734  * valid filename for a filesystem, with printable characters.
1735  *
1736  * We assume that we have a properly initialized crypto context,
1737  * pointed to by crypt_stat->tfm.
1738  *
1739  * TODO: Implement filename decoding and decryption here, in place of
1740  * memcpy. We are keeping the framework around for now to (1)
1741  * facilitate testing of the components needed to implement filename
1742  * encryption and (2) to provide a code base from which other
1743  * developers in the community can easily implement this feature.
1744  *
1745  * Returns the length of encoded filename; negative if error
1746  */
1747 int
1748 ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1749                          const char *name, int length, char **encoded_name)
1750 {
1751         int error = 0;
1752
1753         (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1754         if (!(*encoded_name)) {
1755                 error = -ENOMEM;
1756                 goto out;
1757         }
1758         /* TODO: Filename encryption is a scheduled feature for a
1759          * future version of eCryptfs. This function is here only for
1760          * the purpose of providing a framework for other developers
1761          * to easily implement filename encryption. Hint: Replace this
1762          * memcpy() with a call to encrypt and encode the
1763          * filename, the set the length accordingly. */
1764         memcpy((void *)(*encoded_name), (void *)name, length);
1765         (*encoded_name)[length] = '\0';
1766         error = length + 1;
1767 out:
1768         return error;
1769 }
1770
1771 /**
1772  * ecryptfs_decode_filename - converts the cipher text name to plaintext
1773  * @crypt_stat: The crypt_stat struct associated with the file
1774  * @name: The filename in cipher text
1775  * @length: The length of the cipher text name
1776  * @decrypted_name: The plaintext name
1777  *
1778  * Decodes and decrypts the filename.
1779  *
1780  * We assume that we have a properly initialized crypto context,
1781  * pointed to by crypt_stat->tfm.
1782  *
1783  * TODO: Implement filename decoding and decryption here, in place of
1784  * memcpy. We are keeping the framework around for now to (1)
1785  * facilitate testing of the components needed to implement filename
1786  * encryption and (2) to provide a code base from which other
1787  * developers in the community can easily implement this feature.
1788  *
1789  * Returns the length of decoded filename; negative if error
1790  */
1791 int
1792 ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1793                          const char *name, int length, char **decrypted_name)
1794 {
1795         int error = 0;
1796
1797         (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1798         if (!(*decrypted_name)) {
1799                 error = -ENOMEM;
1800                 goto out;
1801         }
1802         /* TODO: Filename encryption is a scheduled feature for a
1803          * future version of eCryptfs. This function is here only for
1804          * the purpose of providing a framework for other developers
1805          * to easily implement filename encryption. Hint: Replace this
1806          * memcpy() with a call to decode and decrypt the
1807          * filename, the set the length accordingly. */
1808         memcpy((void *)(*decrypted_name), (void *)name, length);
1809         (*decrypted_name)[length + 1] = '\0';   /* Only for convenience
1810                                                  * in printing out the
1811                                                  * string in debug
1812                                                  * messages */
1813         error = length;
1814 out:
1815         return error;
1816 }
1817
1818 /**
1819  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1820  * @key_tfm: Crypto context for key material, set by this function
1821  * @cipher_name: Name of the cipher
1822  * @key_size: Size of the key in bytes
1823  *
1824  * Returns zero on success. Any crypto_tfm structs allocated here
1825  * should be released by other functions, such as on a superblock put
1826  * event, regardless of whether this function succeeds for fails.
1827  */
1828 int
1829 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1830                             char *cipher_name, size_t *key_size)
1831 {
1832         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1833         char *full_alg_name;
1834         int rc;
1835
1836         *key_tfm = NULL;
1837         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1838                 rc = -EINVAL;
1839                 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1840                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1841                 goto out;
1842         }
1843         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1844                                                     "ecb");
1845         if (rc)
1846                 goto out;
1847         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1848         kfree(full_alg_name);
1849         if (IS_ERR(*key_tfm)) {
1850                 rc = PTR_ERR(*key_tfm);
1851                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1852                        "[%s]; rc = [%d]\n", cipher_name, rc);
1853                 goto out;
1854         }
1855         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1856         if (*key_size == 0) {
1857                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1858
1859                 *key_size = alg->max_keysize;
1860         }
1861         get_random_bytes(dummy_key, *key_size);
1862         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1863         if (rc) {
1864                 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1865                        "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
1866                 rc = -EINVAL;
1867                 goto out;
1868         }
1869 out:
1870         return rc;
1871 }
1872
1873 struct kmem_cache *ecryptfs_key_tfm_cache;
1874 struct list_head key_tfm_list;
1875 struct mutex key_tfm_list_mutex;
1876
1877 int ecryptfs_init_crypto(void)
1878 {
1879         mutex_init(&key_tfm_list_mutex);
1880         INIT_LIST_HEAD(&key_tfm_list);
1881         return 0;
1882 }
1883
1884 int ecryptfs_destruct_crypto(void)
1885 {
1886         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1887
1888         mutex_lock(&key_tfm_list_mutex);
1889         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1890                                  key_tfm_list) {
1891                 list_del(&key_tfm->key_tfm_list);
1892                 if (key_tfm->key_tfm)
1893                         crypto_free_blkcipher(key_tfm->key_tfm);
1894                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1895         }
1896         mutex_unlock(&key_tfm_list_mutex);
1897         return 0;
1898 }
1899
1900 int
1901 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1902                          size_t key_size)
1903 {
1904         struct ecryptfs_key_tfm *tmp_tfm;
1905         int rc = 0;
1906
1907         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1908         if (key_tfm != NULL)
1909                 (*key_tfm) = tmp_tfm;
1910         if (!tmp_tfm) {
1911                 rc = -ENOMEM;
1912                 printk(KERN_ERR "Error attempting to allocate from "
1913                        "ecryptfs_key_tfm_cache\n");
1914                 goto out;
1915         }
1916         mutex_init(&tmp_tfm->key_tfm_mutex);
1917         strncpy(tmp_tfm->cipher_name, cipher_name,
1918                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1919         tmp_tfm->key_size = key_size;
1920         if ((rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1921                                               tmp_tfm->cipher_name,
1922                                               &tmp_tfm->key_size))) {
1923                 printk(KERN_ERR "Error attempting to initialize key TFM "
1924                        "cipher with name = [%s]; rc = [%d]\n",
1925                        tmp_tfm->cipher_name, rc);
1926                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1927                 if (key_tfm != NULL)
1928                         (*key_tfm) = NULL;
1929                 goto out;
1930         }
1931         mutex_lock(&key_tfm_list_mutex);
1932         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1933         mutex_unlock(&key_tfm_list_mutex);
1934 out:
1935         return rc;
1936 }
1937
1938 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1939                                                struct mutex **tfm_mutex,
1940                                                char *cipher_name)
1941 {
1942         struct ecryptfs_key_tfm *key_tfm;
1943         int rc = 0;
1944
1945         (*tfm) = NULL;
1946         (*tfm_mutex) = NULL;
1947         mutex_lock(&key_tfm_list_mutex);
1948         list_for_each_entry(key_tfm, &key_tfm_list, key_tfm_list) {
1949                 if (strcmp(key_tfm->cipher_name, cipher_name) == 0) {
1950                         (*tfm) = key_tfm->key_tfm;
1951                         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1952                         mutex_unlock(&key_tfm_list_mutex);
1953                         goto out;
1954                 }
1955         }
1956         mutex_unlock(&key_tfm_list_mutex);
1957         if ((rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0))) {
1958                 printk(KERN_ERR "Error adding new key_tfm to list; rc = [%d]\n",
1959                        rc);
1960                 goto out;
1961         }
1962         (*tfm) = key_tfm->key_tfm;
1963         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1964 out:
1965         return rc;
1966 }