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