fs/ecryptfs/crypto.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * eCryptfs: Linux filesystem encryption layer
   4  *
   5  * Copyright (C) 1997-2004 Erez Zadok
   6  * Copyright (C) 2001-2004 Stony Brook University
   7  * Copyright (C) 2004-2007 International Business Machines Corp.
   8  *   Author(s): Michael A. Halcrow <[email protected]>
   9  *              Michael C. Thompson <[email protected]>
  10  */
  11
  12 #include <crypto/hash.h>
  13 #include <crypto/skcipher.h>
  14 #include <linux/fs.h>
  15 #include <linux/mount.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/random.h>
  18 #include <linux/compiler.h>
  19 #include <linux/key.h>
  20 #include <linux/namei.h>
  21 #include <linux/file.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/slab.h>
  24 #include <linux/unaligned.h>
  25 #include <linux/kernel.h>
  26 #include <linux/xattr.h>
  27 #include "ecryptfs_kernel.h"
  28
  29 #define DECRYPT         0
  30 #define ENCRYPT         1
  31
  32 /**
  33  * ecryptfs_from_hex
  34  * @dst: Buffer to take the bytes from src hex; must be at least of
  35  *       size (src_size / 2)
  36  * @src: Buffer to be converted from a hex string representation to raw value
  37  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  38  */
  39 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  40 {
  41         int x;
  42         char tmp[3] = { 0, };
  43
  44         for (x = 0; x < dst_size; x++) {
  45                 tmp[0] = src[x * 2];
  46                 tmp[1] = src[x * 2 + 1];
  47                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  48         }
  49 }
  50
  51 /**
  52  * ecryptfs_calculate_md5 - calculates the md5 of @src
  53  * @dst: Pointer to 16 bytes of allocated memory
  54  * @crypt_stat: Pointer to crypt_stat struct for the current inode
  55  * @src: Data to be md5'd
  56  * @len: Length of @src
  57  *
  58  * Uses the allocated crypto context that crypt_stat references to
  59  * generate the MD5 sum of the contents of src.
  60  */
  61 static int ecryptfs_calculate_md5(char *dst,
  62                                   struct ecryptfs_crypt_stat *crypt_stat,
  63                                   char *src, int len)
  64 {
  65         int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst);
  66
  67         if (rc) {
  68                 printk(KERN_ERR
  69                        "%s: Error computing crypto hash; rc = [%d]\n",
  70                        __func__, rc);
  71                 goto out;
  72         }
  73 out:
  74         return rc;
  75 }
  76
  77 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
  78                                                   char *cipher_name,
  79                                                   char *chaining_modifier)
  80 {
  81         int cipher_name_len = strlen(cipher_name);
  82         int chaining_modifier_len = strlen(chaining_modifier);
  83         int algified_name_len;
  84         int rc;
  85
  86         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
  87         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
  88         if (!(*algified_name)) {
  89                 rc = -ENOMEM;
  90                 goto out;
  91         }
  92         snprintf((*algified_name), algified_name_len, "%s(%s)",
  93                  chaining_modifier, cipher_name);
  94         rc = 0;
  95 out:
  96         return rc;
  97 }
  98
  99 /**
 100  * ecryptfs_derive_iv
 101  * @iv: destination for the derived iv vale
 102  * @crypt_stat: Pointer to crypt_stat struct for the current inode
 103  * @offset: Offset of the extent whose IV we are to derive
 104  *
 105  * Generate the initialization vector from the given root IV and page
 106  * offset.
 107  *
 108  * Returns zero on success; non-zero on error.
 109  */
 110 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 111                        loff_t offset)
 112 {
 113         int rc = 0;
 114         char dst[MD5_DIGEST_SIZE];
 115         char src[ECRYPTFS_MAX_IV_BYTES + 16];
 116
 117         if (unlikely(ecryptfs_verbosity > 0)) {
 118                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 119                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 120         }
 121         /* TODO: It is probably secure to just cast the least
 122          * significant bits of the root IV into an unsigned long and
 123          * add the offset to that rather than go through all this
 124          * hashing business. -Halcrow */
 125         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 126         memset((src + crypt_stat->iv_bytes), 0, 16);
 127         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
 128         if (unlikely(ecryptfs_verbosity > 0)) {
 129                 ecryptfs_printk(KERN_DEBUG, "source:\n");
 130                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 131         }
 132         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 133                                     (crypt_stat->iv_bytes + 16));
 134         if (rc) {
 135                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 136                                 "MD5 while generating IV for a page\n");
 137                 goto out;
 138         }
 139         memcpy(iv, dst, crypt_stat->iv_bytes);
 140         if (unlikely(ecryptfs_verbosity > 0)) {
 141                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 142                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 143         }
 144 out:
 145         return rc;
 146 }
 147
 148 /**
 149  * ecryptfs_init_crypt_stat
 150  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 151  *
 152  * Initialize the crypt_stat structure.
 153  */
 154 int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 155 {
 156         struct crypto_shash *tfm;
 157         int rc;
 158
 159         tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
 160         if (IS_ERR(tfm)) {
 161                 rc = PTR_ERR(tfm);
 162                 ecryptfs_printk(KERN_ERR, "Error attempting to "
 163                                 "allocate crypto context; rc = [%d]\n",
 164                                 rc);
 165                 return rc;
 166         }
 167
 168         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 169         INIT_LIST_HEAD(&crypt_stat->keysig_list);
 170         mutex_init(&crypt_stat->keysig_list_mutex);
 171         mutex_init(&crypt_stat->cs_mutex);
 172         mutex_init(&crypt_stat->cs_tfm_mutex);
 173         crypt_stat->hash_tfm = tfm;
 174         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 175
 176         return 0;
 177 }
 178
 179 /**
 180  * ecryptfs_destroy_crypt_stat
 181  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 182  *
 183  * Releases all memory associated with a crypt_stat struct.
 184  */
 185 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 186 {
 187         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 188
 189         crypto_free_skcipher(crypt_stat->tfm);
 190         crypto_free_shash(crypt_stat->hash_tfm);
 191         list_for_each_entry_safe(key_sig, key_sig_tmp,
 192                                  &crypt_stat->keysig_list, crypt_stat_list) {
 193                 list_del(&key_sig->crypt_stat_list);
 194                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 195         }
 196         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 197 }
 198
 199 void ecryptfs_destroy_mount_crypt_stat(
 200         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 201 {
 202         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 203
 204         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 205                 return;
 206         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 207         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 208                                  &mount_crypt_stat->global_auth_tok_list,
 209                                  mount_crypt_stat_list) {
 210                 list_del(&auth_tok->mount_crypt_stat_list);
 211                 if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 212                         key_put(auth_tok->global_auth_tok_key);
 213                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 214         }
 215         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 216         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 217 }
 218
 219 /**
 220  * virt_to_scatterlist
 221  * @addr: Virtual address
 222  * @size: Size of data; should be an even multiple of the block size
 223  * @sg: Pointer to scatterlist array; set to NULL to obtain only
 224  *      the number of scatterlist structs required in array
 225  * @sg_size: Max array size
 226  *
 227  * Fills in a scatterlist array with page references for a passed
 228  * virtual address.
 229  *
 230  * Returns the number of scatterlist structs in array used
 231  */
 232 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 233                         int sg_size)
 234 {
 235         int i = 0;
 236         struct page *pg;
 237         int offset;
 238         int remainder_of_page;
 239
 240         sg_init_table(sg, sg_size);
 241
 242         while (size > 0 && i < sg_size) {
 243                 pg = virt_to_page(addr);
 244                 offset = offset_in_page(addr);
 245                 sg_set_page(&sg[i], pg, 0, offset);
 246                 remainder_of_page = PAGE_SIZE - offset;
 247                 if (size >= remainder_of_page) {
 248                         sg[i].length = remainder_of_page;
 249                         addr += remainder_of_page;
 250                         size -= remainder_of_page;
 251                 } else {
 252                         sg[i].length = size;
 253                         addr += size;
 254                         size = 0;
 255                 }
 256                 i++;
 257         }
 258         if (size > 0)
 259                 return -ENOMEM;
 260         return i;
 261 }
 262
 263 /**
 264  * crypt_scatterlist
 265  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 266  * @dst_sg: Destination of the data after performing the crypto operation
 267  * @src_sg: Data to be encrypted or decrypted
 268  * @size: Length of data
 269  * @iv: IV to use
 270  * @op: ENCRYPT or DECRYPT to indicate the desired operation
 271  *
 272  * Returns the number of bytes encrypted or decrypted; negative value on error
 273  */
 274 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 275                              struct scatterlist *dst_sg,
 276                              struct scatterlist *src_sg, int size,
 277                              unsigned char *iv, int op)
 278 {
 279         struct skcipher_request *req = NULL;
 280         DECLARE_CRYPTO_WAIT(ecr);
 281         int rc = 0;
 282
 283         if (unlikely(ecryptfs_verbosity > 0)) {
 284                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 285                                 crypt_stat->key_size);
 286                 ecryptfs_dump_hex(crypt_stat->key,
 287                                   crypt_stat->key_size);
 288         }
 289
 290         mutex_lock(&crypt_stat->cs_tfm_mutex);
 291         req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
 292         if (!req) {
 293                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 294                 rc = -ENOMEM;
 295                 goto out;
 296         }
 297
 298         skcipher_request_set_callback(req,
 299                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 300                         crypto_req_done, &ecr);
 301         /* Consider doing this once, when the file is opened */
 302         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 303                 rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 304                                             crypt_stat->key_size);
 305                 if (rc) {
 306                         ecryptfs_printk(KERN_ERR,
 307                                         "Error setting key; rc = [%d]\n",
 308                                         rc);
 309                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 310                         rc = -EINVAL;
 311                         goto out;
 312                 }
 313                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
 314         }
 315         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 316         skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 317         rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
 318                              crypto_skcipher_decrypt(req);
 319         rc = crypto_wait_req(rc, &ecr);
 320 out:
 321         skcipher_request_free(req);
 322         return rc;
 323 }
 324
 325 /*
 326  * lower_offset_for_page
 327  *
 328  * Convert an eCryptfs page index into a lower byte offset
 329  */
 330 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 331                                     struct folio *folio)
 332 {
 333         return ecryptfs_lower_header_size(crypt_stat) +
 334                (loff_t)folio->index * PAGE_SIZE;
 335 }
 336
 337 /**
 338  * crypt_extent
 339  * @crypt_stat: crypt_stat containing cryptographic context for the
 340  *              encryption operation
 341  * @dst_page: The page to write the result into
 342  * @src_page: The page to read from
 343  * @page_index: The offset in the file (in units of PAGE_SIZE)
 344  * @extent_offset: Page extent offset for use in generating IV
 345  * @op: ENCRYPT or DECRYPT to indicate the desired operation
 346  *
 347  * Encrypts or decrypts one extent of data.
 348  *
 349  * Return zero on success; non-zero otherwise
 350  */
 351 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 352                         struct page *dst_page,
 353                         struct page *src_page,
 354                         pgoff_t page_index,
 355                         unsigned long extent_offset, int op)
 356 {
 357         loff_t extent_base;
 358         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 359         struct scatterlist src_sg, dst_sg;
 360         size_t extent_size = crypt_stat->extent_size;
 361         int rc;
 362
 363         extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
 364         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 365                                 (extent_base + extent_offset));
 366         if (rc) {
 367                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 368                         "extent [0x%.16llx]; rc = [%d]\n",
 369                         (unsigned long long)(extent_base + extent_offset), rc);
 370                 goto out;
 371         }
 372
 373         sg_init_table(&src_sg, 1);
 374         sg_init_table(&dst_sg, 1);
 375
 376         sg_set_page(&src_sg, src_page, extent_size,
 377                     extent_offset * extent_size);
 378         sg_set_page(&dst_sg, dst_page, extent_size,
 379                     extent_offset * extent_size);
 380
 381         rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 382                                extent_iv, op);
 383         if (rc < 0) {
 384                 printk(KERN_ERR "%s: Error attempting to crypt page with "
 385                        "page_index = [%ld], extent_offset = [%ld]; "
 386                        "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 387                 goto out;
 388         }
 389         rc = 0;
 390 out:
 391         return rc;
 392 }
 393
 394 /**
 395  * ecryptfs_encrypt_page
 396  * @folio: Folio mapped from the eCryptfs inode for the file; contains
 397  *        decrypted content that needs to be encrypted (to a temporary
 398  *        page; not in place) and written out to the lower file
 399  *
 400  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 401  * that eCryptfs pages may straddle the lower pages -- for instance,
 402  * if the file was created on a machine with an 8K page size
 403  * (resulting in an 8K header), and then the file is copied onto a
 404  * host with a 32K page size, then when reading page 0 of the eCryptfs
 405  * file, 24K of page 0 of the lower file will be read and decrypted,
 406  * and then 8K of page 1 of the lower file will be read and decrypted.
 407  *
 408  * Returns zero on success; negative on error
 409  */
 410 int ecryptfs_encrypt_page(struct folio *folio)
 411 {
 412         struct inode *ecryptfs_inode;
 413         struct ecryptfs_crypt_stat *crypt_stat;
 414         char *enc_extent_virt;
 415         struct page *enc_extent_page = NULL;
 416         loff_t extent_offset;
 417         loff_t lower_offset;
 418         int rc = 0;
 419
 420         ecryptfs_inode = folio->mapping->host;
 421         crypt_stat =
 422                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 423         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 424         enc_extent_page = alloc_page(GFP_USER);
 425         if (!enc_extent_page) {
 426                 rc = -ENOMEM;
 427                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 428                                 "encrypted extent\n");
 429                 goto out;
 430         }
 431
 432         for (extent_offset = 0;
 433              extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 434              extent_offset++) {
 435                 rc = crypt_extent(crypt_stat, enc_extent_page,
 436                                 folio_page(folio, 0), folio->index,
 437                                 extent_offset, ENCRYPT);
 438                 if (rc) {
 439                         printk(KERN_ERR "%s: Error encrypting extent; "
 440                                "rc = [%d]\n", __func__, rc);
 441                         goto out;
 442                 }
 443         }
 444
 445         lower_offset = lower_offset_for_page(crypt_stat, folio);
 446         enc_extent_virt = kmap_local_page(enc_extent_page);
 447         rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 448                                   PAGE_SIZE);
 449         kunmap_local(enc_extent_virt);
 450         if (rc < 0) {
 451                 ecryptfs_printk(KERN_ERR,
 452                         "Error attempting to write lower page; rc = [%d]\n",
 453                         rc);
 454                 goto out;
 455         }
 456         rc = 0;
 457 out:
 458         if (enc_extent_page) {
 459                 __free_page(enc_extent_page);
 460         }
 461         return rc;
 462 }
 463
 464 /**
 465  * ecryptfs_decrypt_page
 466  * @folio: Folio mapped from the eCryptfs inode for the file; data read
 467  *        and decrypted from the lower file will be written into this
 468  *        page
 469  *
 470  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 471  * that eCryptfs pages may straddle the lower pages -- for instance,
 472  * if the file was created on a machine with an 8K page size
 473  * (resulting in an 8K header), and then the file is copied onto a
 474  * host with a 32K page size, then when reading page 0 of the eCryptfs
 475  * file, 24K of page 0 of the lower file will be read and decrypted,
 476  * and then 8K of page 1 of the lower file will be read and decrypted.
 477  *
 478  * Returns zero on success; negative on error
 479  */
 480 int ecryptfs_decrypt_page(struct folio *folio)
 481 {
 482         struct inode *ecryptfs_inode;
 483         struct ecryptfs_crypt_stat *crypt_stat;
 484         char *page_virt;
 485         unsigned long extent_offset;
 486         loff_t lower_offset;
 487         int rc = 0;
 488
 489         ecryptfs_inode = folio->mapping->host;
 490         crypt_stat =
 491                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 492         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 493
 494         lower_offset = lower_offset_for_page(crypt_stat, folio);
 495         page_virt = kmap_local_folio(folio, 0);
 496         rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
 497                                  ecryptfs_inode);
 498         kunmap_local(page_virt);
 499         if (rc < 0) {
 500                 ecryptfs_printk(KERN_ERR,
 501                         "Error attempting to read lower page; rc = [%d]\n",
 502                         rc);
 503                 goto out;
 504         }
 505
 506         for (extent_offset = 0;
 507              extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
 508              extent_offset++) {
 509                 struct page *page = folio_page(folio, 0);
 510                 rc = crypt_extent(crypt_stat, page, page, folio->index,
 511                                 extent_offset, DECRYPT);
 512                 if (rc) {
 513                         printk(KERN_ERR "%s: Error decrypting extent; "
 514                                "rc = [%d]\n", __func__, rc);
 515                         goto out;
 516                 }
 517         }
 518 out:
 519         return rc;
 520 }
 521
 522 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 523
 524 /**
 525  * ecryptfs_init_crypt_ctx
 526  * @crypt_stat: Uninitialized crypt stats structure
 527  *
 528  * Initialize the crypto context.
 529  *
 530  * TODO: Performance: Keep a cache of initialized cipher contexts;
 531  * only init if needed
 532  */
 533 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 534 {
 535         char *full_alg_name;
 536         int rc = -EINVAL;
 537
 538         ecryptfs_printk(KERN_DEBUG,
 539                         "Initializing cipher [%s]; strlen = [%d]; "
 540                         "key_size_bits = [%zd]\n",
 541                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 542                         crypt_stat->key_size << 3);
 543         mutex_lock(&crypt_stat->cs_tfm_mutex);
 544         if (crypt_stat->tfm) {
 545                 rc = 0;
 546                 goto out_unlock;
 547         }
 548         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 549                                                     crypt_stat->cipher, "cbc");
 550         if (rc)
 551                 goto out_unlock;
 552         crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
 553         if (IS_ERR(crypt_stat->tfm)) {
 554                 rc = PTR_ERR(crypt_stat->tfm);
 555                 crypt_stat->tfm = NULL;
 556                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 557                                 "Error initializing cipher [%s]\n",
 558                                 full_alg_name);
 559                 goto out_free;
 560         }
 561         crypto_skcipher_set_flags(crypt_stat->tfm,
 562                                   CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
 563         rc = 0;
 564 out_free:
 565         kfree(full_alg_name);
 566 out_unlock:
 567         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 568         return rc;
 569 }
 570
 571 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 572 {
 573         int extent_size_tmp;
 574
 575         crypt_stat->extent_mask = 0xFFFFFFFF;
 576         crypt_stat->extent_shift = 0;
 577         if (crypt_stat->extent_size == 0)
 578                 return;
 579         extent_size_tmp = crypt_stat->extent_size;
 580         while ((extent_size_tmp & 0x01) == 0) {
 581                 extent_size_tmp >>= 1;
 582                 crypt_stat->extent_mask <<= 1;
 583                 crypt_stat->extent_shift++;
 584         }
 585 }
 586
 587 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 588 {
 589         /* Default values; may be overwritten as we are parsing the
 590          * packets. */
 591         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 592         set_extent_mask_and_shift(crypt_stat);
 593         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 594         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 595                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 596         else {
 597                 if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 598                         crypt_stat->metadata_size =
 599                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 600                 else
 601                         crypt_stat->metadata_size = PAGE_SIZE;
 602         }
 603 }
 604
 605 /*
 606  * ecryptfs_compute_root_iv
 607  *
 608  * On error, sets the root IV to all 0's.
 609  */
 610 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 611 {
 612         int rc = 0;
 613         char dst[MD5_DIGEST_SIZE];
 614
 615         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 616         BUG_ON(crypt_stat->iv_bytes <= 0);
 617         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 618                 rc = -EINVAL;
 619                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 620                                 "cannot generate root IV\n");
 621                 goto out;
 622         }
 623         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 624                                     crypt_stat->key_size);
 625         if (rc) {
 626                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 627                                 "MD5 while generating root IV\n");
 628                 goto out;
 629         }
 630         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 631 out:
 632         if (rc) {
 633                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 634                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 635         }
 636         return rc;
 637 }
 638
 639 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 640 {
 641         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 642         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 643         ecryptfs_compute_root_iv(crypt_stat);
 644         if (unlikely(ecryptfs_verbosity > 0)) {
 645                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 646                 ecryptfs_dump_hex(crypt_stat->key,
 647                                   crypt_stat->key_size);
 648         }
 649 }
 650
 651 /**
 652  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 653  * @crypt_stat: The inode's cryptographic context
 654  * @mount_crypt_stat: The mount point's cryptographic context
 655  *
 656  * This function propagates the mount-wide flags to individual inode
 657  * flags.
 658  */
 659 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 660         struct ecryptfs_crypt_stat *crypt_stat,
 661         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 662 {
 663         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 664                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 665         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 666                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 667         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 668                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 669                 if (mount_crypt_stat->flags
 670                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 671                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 672                 else if (mount_crypt_stat->flags
 673                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 674                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 675         }
 676 }
 677
 678 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 679         struct ecryptfs_crypt_stat *crypt_stat,
 680         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 681 {
 682         struct ecryptfs_global_auth_tok *global_auth_tok;
 683         int rc = 0;
 684
 685         mutex_lock(&crypt_stat->keysig_list_mutex);
 686         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 687
 688         list_for_each_entry(global_auth_tok,
 689                             &mount_crypt_stat->global_auth_tok_list,
 690                             mount_crypt_stat_list) {
 691                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 692                         continue;
 693                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 694                 if (rc) {
 695                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 696                         goto out;
 697                 }
 698         }
 699
 700 out:
 701         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 702         mutex_unlock(&crypt_stat->keysig_list_mutex);
 703         return rc;
 704 }
 705
 706 /**
 707  * ecryptfs_set_default_crypt_stat_vals
 708  * @crypt_stat: The inode's cryptographic context
 709  * @mount_crypt_stat: The mount point's cryptographic context
 710  *
 711  * Default values in the event that policy does not override them.
 712  */
 713 static void ecryptfs_set_default_crypt_stat_vals(
 714         struct ecryptfs_crypt_stat *crypt_stat,
 715         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 716 {
 717         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 718                                                       mount_crypt_stat);
 719         ecryptfs_set_default_sizes(crypt_stat);
 720         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 721         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 722         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 723         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 724         crypt_stat->mount_crypt_stat = mount_crypt_stat;
 725 }
 726
 727 /**
 728  * ecryptfs_new_file_context
 729  * @ecryptfs_inode: The eCryptfs inode
 730  *
 731  * If the crypto context for the file has not yet been established,
 732  * this is where we do that.  Establishing a new crypto context
 733  * involves the following decisions:
 734  *  - What cipher to use?
 735  *  - What set of authentication tokens to use?
 736  * Here we just worry about getting enough information into the
 737  * authentication tokens so that we know that they are available.
 738  * We associate the available authentication tokens with the new file
 739  * via the set of signatures in the crypt_stat struct.  Later, when
 740  * the headers are actually written out, we may again defer to
 741  * userspace to perform the encryption of the session key; for the
 742  * foreseeable future, this will be the case with public key packets.
 743  *
 744  * Returns zero on success; non-zero otherwise
 745  */
 746 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 747 {
 748         struct ecryptfs_crypt_stat *crypt_stat =
 749             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 750         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 751             &ecryptfs_superblock_to_private(
 752                     ecryptfs_inode->i_sb)->mount_crypt_stat;
 753         int cipher_name_len;
 754         int rc = 0;
 755
 756         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 757         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 758         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 759                                                       mount_crypt_stat);
 760         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 761                                                          mount_crypt_stat);
 762         if (rc) {
 763                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 764                        "to the inode key sigs; rc = [%d]\n", rc);
 765                 goto out;
 766         }
 767         cipher_name_len =
 768                 strlen(mount_crypt_stat->global_default_cipher_name);
 769         memcpy(crypt_stat->cipher,
 770                mount_crypt_stat->global_default_cipher_name,
 771                cipher_name_len);
 772         crypt_stat->cipher[cipher_name_len] = '\0';
 773         crypt_stat->key_size =
 774                 mount_crypt_stat->global_default_cipher_key_size;
 775         ecryptfs_generate_new_key(crypt_stat);
 776         rc = ecryptfs_init_crypt_ctx(crypt_stat);
 777         if (rc)
 778                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 779                                 "context for cipher [%s]: rc = [%d]\n",
 780                                 crypt_stat->cipher, rc);
 781 out:
 782         return rc;
 783 }
 784
 785 /**
 786  * ecryptfs_validate_marker - check for the ecryptfs marker
 787  * @data: The data block in which to check
 788  *
 789  * Returns zero if marker found; -EINVAL if not found
 790  */
 791 static int ecryptfs_validate_marker(char *data)
 792 {
 793         u32 m_1, m_2;
 794
 795         m_1 = get_unaligned_be32(data);
 796         m_2 = get_unaligned_be32(data + 4);
 797         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 798                 return 0;
 799         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
 800                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
 801                         MAGIC_ECRYPTFS_MARKER);
 802         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
 803                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
 804         return -EINVAL;
 805 }
 806
 807 struct ecryptfs_flag_map_elem {
 808         u32 file_flag;
 809         u32 local_flag;
 810 };
 811
 812 /* Add support for additional flags by adding elements here. */
 813 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 814         {0x00000001, ECRYPTFS_ENABLE_HMAC},
 815         {0x00000002, ECRYPTFS_ENCRYPTED},
 816         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
 817         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 818 };
 819
 820 /**
 821  * ecryptfs_process_flags
 822  * @crypt_stat: The cryptographic context
 823  * @page_virt: Source data to be parsed
 824  * @bytes_read: Updated with the number of bytes read
 825  */
 826 static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
 827                                   char *page_virt, int *bytes_read)
 828 {
 829         int i;
 830         u32 flags;
 831
 832         flags = get_unaligned_be32(page_virt);
 833         for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
 834                 if (flags & ecryptfs_flag_map[i].file_flag) {
 835                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
 836                 } else
 837                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
 838         /* Version is in top 8 bits of the 32-bit flag vector */
 839         crypt_stat->file_version = ((flags >> 24) & 0xFF);
 840         (*bytes_read) = 4;
 841 }
 842
 843 /**
 844  * write_ecryptfs_marker
 845  * @page_virt: The pointer to in a page to begin writing the marker
 846  * @written: Number of bytes written
 847  *
 848  * Marker = 0x3c81b7f5
 849  */
 850 static void write_ecryptfs_marker(char *page_virt, size_t *written)
 851 {
 852         u32 m_1, m_2;
 853
 854         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 855         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 856         put_unaligned_be32(m_1, page_virt);
 857         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 858         put_unaligned_be32(m_2, page_virt);
 859         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 860 }
 861
 862 void ecryptfs_write_crypt_stat_flags(char *page_virt,
 863                                      struct ecryptfs_crypt_stat *crypt_stat,
 864                                      size_t *written)
 865 {
 866         u32 flags = 0;
 867         int i;
 868
 869         for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
 870                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
 871                         flags |= ecryptfs_flag_map[i].file_flag;
 872         /* Version is in top 8 bits of the 32-bit flag vector */
 873         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
 874         put_unaligned_be32(flags, page_virt);
 875         (*written) = 4;
 876 }
 877
 878 struct ecryptfs_cipher_code_str_map_elem {
 879         char cipher_str[16];
 880         u8 cipher_code;
 881 };
 882
 883 /* Add support for additional ciphers by adding elements here. The
 884  * cipher_code is whatever OpenPGP applications use to identify the
 885  * ciphers. List in order of probability. */
 886 static struct ecryptfs_cipher_code_str_map_elem
 887 ecryptfs_cipher_code_str_map[] = {
 888         {"aes",RFC2440_CIPHER_AES_128 },
 889         {"blowfish", RFC2440_CIPHER_BLOWFISH},
 890         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
 891         {"cast5", RFC2440_CIPHER_CAST_5},
 892         {"twofish", RFC2440_CIPHER_TWOFISH},
 893         {"cast6", RFC2440_CIPHER_CAST_6},
 894         {"aes", RFC2440_CIPHER_AES_192},
 895         {"aes", RFC2440_CIPHER_AES_256}
 896 };
 897
 898 /**
 899  * ecryptfs_code_for_cipher_string
 900  * @cipher_name: The string alias for the cipher
 901  * @key_bytes: Length of key in bytes; used for AES code selection
 902  *
 903  * Returns zero on no match, or the cipher code on match
 904  */
 905 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 906 {
 907         int i;
 908         u8 code = 0;
 909         struct ecryptfs_cipher_code_str_map_elem *map =
 910                 ecryptfs_cipher_code_str_map;
 911
 912         if (strcmp(cipher_name, "aes") == 0) {
 913                 switch (key_bytes) {
 914                 case 16:
 915                         code = RFC2440_CIPHER_AES_128;
 916                         break;
 917                 case 24:
 918                         code = RFC2440_CIPHER_AES_192;
 919                         break;
 920                 case 32:
 921                         code = RFC2440_CIPHER_AES_256;
 922                 }
 923         } else {
 924                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
 925                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
 926                                 code = map[i].cipher_code;
 927                                 break;
 928                         }
 929         }
 930         return code;
 931 }
 932
 933 /**
 934  * ecryptfs_cipher_code_to_string
 935  * @str: Destination to write out the cipher name
 936  * @cipher_code: The code to convert to cipher name string
 937  *
 938  * Returns zero on success
 939  */
 940 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
 941 {
 942         int rc = 0;
 943         int i;
 944
 945         str[0] = '\0';
 946         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
 947                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
 948                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
 949         if (str[0] == '\0') {
 950                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
 951                                 "[%d]\n", cipher_code);
 952                 rc = -EINVAL;
 953         }
 954         return rc;
 955 }
 956
 957 int ecryptfs_read_and_validate_header_region(struct inode *inode)
 958 {
 959         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
 960         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
 961         int rc;
 962
 963         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
 964                                  inode);
 965         if (rc < 0)
 966                 return rc;
 967         else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
 968                 return -EINVAL;
 969         rc = ecryptfs_validate_marker(marker);
 970         if (!rc)
 971                 ecryptfs_i_size_init(file_size, inode);
 972         return rc;
 973 }
 974
 975 void
 976 ecryptfs_write_header_metadata(char *virt,
 977                                struct ecryptfs_crypt_stat *crypt_stat,
 978                                size_t *written)
 979 {
 980         u32 header_extent_size;
 981         u16 num_header_extents_at_front;
 982
 983         header_extent_size = (u32)crypt_stat->extent_size;
 984         num_header_extents_at_front =
 985                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
 986         put_unaligned_be32(header_extent_size, virt);
 987         virt += 4;
 988         put_unaligned_be16(num_header_extents_at_front, virt);
 989         (*written) = 6;
 990 }
 991
 992 struct kmem_cache *ecryptfs_header_cache;
 993
 994 /**
 995  * ecryptfs_write_headers_virt
 996  * @page_virt: The virtual address to write the headers to
 997  * @max: The size of memory allocated at page_virt
 998  * @size: Set to the number of bytes written by this function
 999  * @crypt_stat: The cryptographic context
1000  * @ecryptfs_dentry: The eCryptfs dentry
1001  *
1002  * Format version: 1
1003  *
1004  *   Header Extent:
1005  *     Octets 0-7:        Unencrypted file size (big-endian)
1006  *     Octets 8-15:       eCryptfs special marker
1007  *     Octets 16-19:      Flags
1008  *      Octet 16:         File format version number (between 0 and 255)
1009  *      Octets 17-18:     Reserved
1010  *      Octet 19:         Bit 1 (lsb): Reserved
1011  *                        Bit 2: Encrypted?
1012  *                        Bits 3-8: Reserved
1013  *     Octets 20-23:      Header extent size (big-endian)
1014  *     Octets 24-25:      Number of header extents at front of file
1015  *                        (big-endian)
1016  *     Octet  26:         Begin RFC 2440 authentication token packet set
1017  *   Data Extent 0:
1018  *     Lower data (CBC encrypted)
1019  *   Data Extent 1:
1020  *     Lower data (CBC encrypted)
1021  *   ...
1022  *
1023  * Returns zero on success
1024  */
1025 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1026                                        size_t *size,
1027                                        struct ecryptfs_crypt_stat *crypt_stat,
1028                                        struct dentry *ecryptfs_dentry)
1029 {
1030         int rc;
1031         size_t written;
1032         size_t offset;
1033
1034         offset = ECRYPTFS_FILE_SIZE_BYTES;
1035         write_ecryptfs_marker((page_virt + offset), &written);
1036         offset += written;
1037         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1038                                         &written);
1039         offset += written;
1040         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1041                                        &written);
1042         offset += written;
1043         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1044                                               ecryptfs_dentry, &written,
1045                                               max - offset);
1046         if (rc)
1047                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1048                                 "set; rc = [%d]\n", rc);
1049         if (size) {
1050                 offset += written;
1051                 *size = offset;
1052         }
1053         return rc;
1054 }
1055
1056 static int
1057 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1058                                     char *virt, size_t virt_len)
1059 {
1060         int rc;
1061
1062         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1063                                   0, virt_len);
1064         if (rc < 0)
1065                 printk(KERN_ERR "%s: Error attempting to write header "
1066                        "information to lower file; rc = [%d]\n", __func__, rc);
1067         else
1068                 rc = 0;
1069         return rc;
1070 }
1071
1072 static int
1073 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1074                                  struct inode *ecryptfs_inode,
1075                                  char *page_virt, size_t size)
1076 {
1077         int rc;
1078         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
1079         struct inode *lower_inode = d_inode(lower_dentry);
1080
1081         if (!(lower_inode->i_opflags & IOP_XATTR)) {
1082                 rc = -EOPNOTSUPP;
1083                 goto out;
1084         }
1085
1086         inode_lock(lower_inode);
1087         rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
1088                             ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1089         if (!rc && ecryptfs_inode)
1090                 fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
1091         inode_unlock(lower_inode);
1092 out:
1093         return rc;
1094 }
1095
1096 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1097                                                unsigned int order)
1098 {
1099         struct page *page;
1100
1101         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1102         if (page)
1103                 return (unsigned long) page_address(page);
1104         return 0;
1105 }
1106
1107 /**
1108  * ecryptfs_write_metadata
1109  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1110  * @ecryptfs_inode: The newly created eCryptfs inode
1111  *
1112  * Write the file headers out.  This will likely involve a userspace
1113  * callout, in which the session key is encrypted with one or more
1114  * public keys and/or the passphrase necessary to do the encryption is
1115  * retrieved via a prompt.  Exactly what happens at this point should
1116  * be policy-dependent.
1117  *
1118  * Returns zero on success; non-zero on error
1119  */
1120 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1121                             struct inode *ecryptfs_inode)
1122 {
1123         struct ecryptfs_crypt_stat *crypt_stat =
1124                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1125         unsigned int order;
1126         char *virt;
1127         size_t virt_len;
1128         size_t size = 0;
1129         int rc = 0;
1130
1131         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1132                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1133                         printk(KERN_ERR "Key is invalid; bailing out\n");
1134                         rc = -EINVAL;
1135                         goto out;
1136                 }
1137         } else {
1138                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1139                        __func__);
1140                 rc = -EINVAL;
1141                 goto out;
1142         }
1143         virt_len = crypt_stat->metadata_size;
1144         order = get_order(virt_len);
1145         /* Released in this function */
1146         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1147         if (!virt) {
1148                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1149                 rc = -ENOMEM;
1150                 goto out;
1151         }
1152         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1153         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1154                                          ecryptfs_dentry);
1155         if (unlikely(rc)) {
1156                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1157                        __func__, rc);
1158                 goto out_free;
1159         }
1160         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1161                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1162                                                       virt, size);
1163         else
1164                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1165                                                          virt_len);
1166         if (rc) {
1167                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1168                        "rc = [%d]\n", __func__, rc);
1169                 goto out_free;
1170         }
1171 out_free:
1172         free_pages((unsigned long)virt, order);
1173 out:
1174         return rc;
1175 }
1176
1177 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1178 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1179 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1180                                  char *virt, int *bytes_read,
1181                                  int validate_header_size)
1182 {
1183         int rc = 0;
1184         u32 header_extent_size;
1185         u16 num_header_extents_at_front;
1186
1187         header_extent_size = get_unaligned_be32(virt);
1188         virt += sizeof(__be32);
1189         num_header_extents_at_front = get_unaligned_be16(virt);
1190         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1191                                      * (size_t)header_extent_size));
1192         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1193         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1194             && (crypt_stat->metadata_size
1195                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1196                 rc = -EINVAL;
1197                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1198                        crypt_stat->metadata_size);
1199         }
1200         return rc;
1201 }
1202
1203 /**
1204  * set_default_header_data
1205  * @crypt_stat: The cryptographic context
1206  *
1207  * For version 0 file format; this function is only for backwards
1208  * compatibility for files created with the prior versions of
1209  * eCryptfs.
1210  */
1211 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1212 {
1213         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1214 }
1215
1216 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1217 {
1218         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1219         struct ecryptfs_crypt_stat *crypt_stat;
1220         u64 file_size;
1221
1222         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1223         mount_crypt_stat =
1224                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1225         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1226                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1227                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1228                         file_size += crypt_stat->metadata_size;
1229         } else
1230                 file_size = get_unaligned_be64(page_virt);
1231         i_size_write(inode, (loff_t)file_size);
1232         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1233 }
1234
1235 /**
1236  * ecryptfs_read_headers_virt
1237  * @page_virt: The virtual address into which to read the headers
1238  * @crypt_stat: The cryptographic context
1239  * @ecryptfs_dentry: The eCryptfs dentry
1240  * @validate_header_size: Whether to validate the header size while reading
1241  *
1242  * Read/parse the header data. The header format is detailed in the
1243  * comment block for the ecryptfs_write_headers_virt() function.
1244  *
1245  * Returns zero on success
1246  */
1247 static int ecryptfs_read_headers_virt(char *page_virt,
1248                                       struct ecryptfs_crypt_stat *crypt_stat,
1249                                       struct dentry *ecryptfs_dentry,
1250                                       int validate_header_size)
1251 {
1252         int rc = 0;
1253         int offset;
1254         int bytes_read;
1255
1256         ecryptfs_set_default_sizes(crypt_stat);
1257         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1258                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1259         offset = ECRYPTFS_FILE_SIZE_BYTES;
1260         rc = ecryptfs_validate_marker(page_virt + offset);
1261         if (rc)
1262                 goto out;
1263         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1264                 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1265         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1266         ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
1267         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1268                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1269                                 "file version [%d] is supported by this "
1270                                 "version of eCryptfs\n",
1271                                 crypt_stat->file_version,
1272                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1273                 rc = -EINVAL;
1274                 goto out;
1275         }
1276         offset += bytes_read;
1277         if (crypt_stat->file_version >= 1) {
1278                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1279                                            &bytes_read, validate_header_size);
1280                 if (rc) {
1281                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1282                                         "metadata; rc = [%d]\n", rc);
1283                 }
1284                 offset += bytes_read;
1285         } else
1286                 set_default_header_data(crypt_stat);
1287         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1288                                        ecryptfs_dentry);
1289 out:
1290         return rc;
1291 }
1292
1293 /**
1294  * ecryptfs_read_xattr_region
1295  * @page_virt: The vitual address into which to read the xattr data
1296  * @ecryptfs_inode: The eCryptfs inode
1297  *
1298  * Attempts to read the crypto metadata from the extended attribute
1299  * region of the lower file.
1300  *
1301  * Returns zero on success; non-zero on error
1302  */
1303 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1304 {
1305         struct dentry *lower_dentry =
1306                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1307         ssize_t size;
1308         int rc = 0;
1309
1310         size = ecryptfs_getxattr_lower(lower_dentry,
1311                                        ecryptfs_inode_to_lower(ecryptfs_inode),
1312                                        ECRYPTFS_XATTR_NAME,
1313                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1314         if (size < 0) {
1315                 if (unlikely(ecryptfs_verbosity > 0))
1316                         printk(KERN_INFO "Error attempting to read the [%s] "
1317                                "xattr from the lower file; return value = "
1318                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1319                 rc = -EINVAL;
1320                 goto out;
1321         }
1322 out:
1323         return rc;
1324 }
1325
1326 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1327                                             struct inode *inode)
1328 {
1329         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1330         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1331         int rc;
1332
1333         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1334                                      ecryptfs_inode_to_lower(inode),
1335                                      ECRYPTFS_XATTR_NAME, file_size,
1336                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1337         if (rc < 0)
1338                 return rc;
1339         else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1340                 return -EINVAL;
1341         rc = ecryptfs_validate_marker(marker);
1342         if (!rc)
1343                 ecryptfs_i_size_init(file_size, inode);
1344         return rc;
1345 }
1346
1347 /*
1348  * ecryptfs_read_metadata
1349  *
1350  * Common entry point for reading file metadata. From here, we could
1351  * retrieve the header information from the header region of the file,
1352  * the xattr region of the file, or some other repository that is
1353  * stored separately from the file itself. The current implementation
1354  * supports retrieving the metadata information from the file contents
1355  * and from the xattr region.
1356  *
1357  * Returns zero if valid headers found and parsed; non-zero otherwise
1358  */
1359 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1360 {
1361         int rc;
1362         char *page_virt;
1363         struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1364         struct ecryptfs_crypt_stat *crypt_stat =
1365             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1366         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1367                 &ecryptfs_superblock_to_private(
1368                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1369
1370         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1371                                                       mount_crypt_stat);
1372         /* Read the first page from the underlying file */
1373         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1374         if (!page_virt) {
1375                 rc = -ENOMEM;
1376                 goto out;
1377         }
1378         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1379                                  ecryptfs_inode);
1380         if (rc >= 0)
1381                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1382                                                 ecryptfs_dentry,
1383                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1384         if (rc) {
1385                 /* metadata is not in the file header, so try xattrs */
1386                 memset(page_virt, 0, PAGE_SIZE);
1387                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1388                 if (rc) {
1389                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1390                                "file header region or xattr region, inode %lu\n",
1391                                 ecryptfs_inode->i_ino);
1392                         rc = -EINVAL;
1393                         goto out;
1394                 }
1395                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1396                                                 ecryptfs_dentry,
1397                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1398                 if (rc) {
1399                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1400                                "file xattr region either, inode %lu\n",
1401                                 ecryptfs_inode->i_ino);
1402                         rc = -EINVAL;
1403                 }
1404                 if (crypt_stat->mount_crypt_stat->flags
1405                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1406                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1407                 } else {
1408                         printk(KERN_WARNING "Attempt to access file with "
1409                                "crypto metadata only in the extended attribute "
1410                                "region, but eCryptfs was mounted without "
1411                                "xattr support enabled. eCryptfs will not treat "
1412                                "this like an encrypted file, inode %lu\n",
1413                                 ecryptfs_inode->i_ino);
1414                         rc = -EINVAL;
1415                 }
1416         }
1417 out:
1418         if (page_virt) {
1419                 memset(page_virt, 0, PAGE_SIZE);
1420                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1421         }
1422         return rc;
1423 }
1424
1425 /*
1426  * ecryptfs_encrypt_filename - encrypt filename
1427  *
1428  * CBC-encrypts the filename. We do not want to encrypt the same
1429  * filename with the same key and IV, which may happen with hard
1430  * links, so we prepend random bits to each filename.
1431  *
1432  * Returns zero on success; non-zero otherwise
1433  */
1434 static int
1435 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1436                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1437 {
1438         int rc = 0;
1439
1440         filename->encrypted_filename = NULL;
1441         filename->encrypted_filename_size = 0;
1442         if (mount_crypt_stat && (mount_crypt_stat->flags
1443                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1444                 size_t packet_size;
1445                 size_t remaining_bytes;
1446
1447                 rc = ecryptfs_write_tag_70_packet(
1448                         NULL, NULL,
1449                         &filename->encrypted_filename_size,
1450                         mount_crypt_stat, NULL,
1451                         filename->filename_size);
1452                 if (rc) {
1453                         printk(KERN_ERR "%s: Error attempting to get packet "
1454                                "size for tag 72; rc = [%d]\n", __func__,
1455                                rc);
1456                         filename->encrypted_filename_size = 0;
1457                         goto out;
1458                 }
1459                 filename->encrypted_filename =
1460                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1461                 if (!filename->encrypted_filename) {
1462                         rc = -ENOMEM;
1463                         goto out;
1464                 }
1465                 remaining_bytes = filename->encrypted_filename_size;
1466                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1467                                                   &remaining_bytes,
1468                                                   &packet_size,
1469                                                   mount_crypt_stat,
1470                                                   filename->filename,
1471                                                   filename->filename_size);
1472                 if (rc) {
1473                         printk(KERN_ERR "%s: Error attempting to generate "
1474                                "tag 70 packet; rc = [%d]\n", __func__,
1475                                rc);
1476                         kfree(filename->encrypted_filename);
1477                         filename->encrypted_filename = NULL;
1478                         filename->encrypted_filename_size = 0;
1479                         goto out;
1480                 }
1481                 filename->encrypted_filename_size = packet_size;
1482         } else {
1483                 printk(KERN_ERR "%s: No support for requested filename "
1484                        "encryption method in this release\n", __func__);
1485                 rc = -EOPNOTSUPP;
1486                 goto out;
1487         }
1488 out:
1489         return rc;
1490 }
1491
1492 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1493                                   const char *name, size_t name_size)
1494 {
1495         int rc = 0;
1496
1497         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1498         if (!(*copied_name)) {
1499                 rc = -ENOMEM;
1500                 goto out;
1501         }
1502         memcpy((void *)(*copied_name), (void *)name, name_size);
1503         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1504                                                  * in printing out the
1505                                                  * string in debug
1506                                                  * messages */
1507         (*copied_name_size) = name_size;
1508 out:
1509         return rc;
1510 }
1511
1512 /**
1513  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1514  * @key_tfm: Crypto context for key material, set by this function
1515  * @cipher_name: Name of the cipher
1516  * @key_size: Size of the key in bytes
1517  *
1518  * Returns zero on success. Any crypto_tfm structs allocated here
1519  * should be released by other functions, such as on a superblock put
1520  * event, regardless of whether this function succeeds for fails.
1521  */
1522 static int
1523 ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1524                             char *cipher_name, size_t *key_size)
1525 {
1526         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1527         char *full_alg_name = NULL;
1528         int rc;
1529
1530         *key_tfm = NULL;
1531         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1532                 rc = -EINVAL;
1533                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1534                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1535                 goto out;
1536         }
1537         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1538                                                     "ecb");
1539         if (rc)
1540                 goto out;
1541         *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1542         if (IS_ERR(*key_tfm)) {
1543                 rc = PTR_ERR(*key_tfm);
1544                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1545                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1546                 goto out;
1547         }
1548         crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1549         if (*key_size == 0)
1550                 *key_size = crypto_skcipher_max_keysize(*key_tfm);
1551         get_random_bytes(dummy_key, *key_size);
1552         rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1553         if (rc) {
1554                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1555                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1556                        rc);
1557                 rc = -EINVAL;
1558                 goto out;
1559         }
1560 out:
1561         kfree(full_alg_name);
1562         return rc;
1563 }
1564
1565 struct kmem_cache *ecryptfs_key_tfm_cache;
1566 static struct list_head key_tfm_list;
1567 DEFINE_MUTEX(key_tfm_list_mutex);
1568
1569 int __init ecryptfs_init_crypto(void)
1570 {
1571         INIT_LIST_HEAD(&key_tfm_list);
1572         return 0;
1573 }
1574
1575 /**
1576  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1577  *
1578  * Called only at module unload time
1579  */
1580 int ecryptfs_destroy_crypto(void)
1581 {
1582         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1583
1584         mutex_lock(&key_tfm_list_mutex);
1585         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1586                                  key_tfm_list) {
1587                 list_del(&key_tfm->key_tfm_list);
1588                 crypto_free_skcipher(key_tfm->key_tfm);
1589                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1590         }
1591         mutex_unlock(&key_tfm_list_mutex);
1592         return 0;
1593 }
1594
1595 int
1596 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1597                          size_t key_size)
1598 {
1599         struct ecryptfs_key_tfm *tmp_tfm;
1600         int rc = 0;
1601
1602         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1603
1604         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1605         if (key_tfm)
1606                 (*key_tfm) = tmp_tfm;
1607         if (!tmp_tfm) {
1608                 rc = -ENOMEM;
1609                 goto out;
1610         }
1611         mutex_init(&tmp_tfm->key_tfm_mutex);
1612         strscpy(tmp_tfm->cipher_name, cipher_name);
1613         tmp_tfm->key_size = key_size;
1614         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1615                                          tmp_tfm->cipher_name,
1616                                          &tmp_tfm->key_size);
1617         if (rc) {
1618                 printk(KERN_ERR "Error attempting to initialize key TFM "
1619                        "cipher with name = [%s]; rc = [%d]\n",
1620                        tmp_tfm->cipher_name, rc);
1621                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1622                 if (key_tfm)
1623                         (*key_tfm) = NULL;
1624                 goto out;
1625         }
1626         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1627 out:
1628         return rc;
1629 }
1630
1631 /**
1632  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1633  * @cipher_name: the name of the cipher to search for
1634  * @key_tfm: set to corresponding tfm if found
1635  *
1636  * Searches for cached key_tfm matching @cipher_name
1637  * Must be called with &key_tfm_list_mutex held
1638  * Returns 1 if found, with @key_tfm set
1639  * Returns 0 if not found, with @key_tfm set to NULL
1640  */
1641 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1642 {
1643         struct ecryptfs_key_tfm *tmp_key_tfm;
1644
1645         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1646
1647         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1648                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1649                         if (key_tfm)
1650                                 (*key_tfm) = tmp_key_tfm;
1651                         return 1;
1652                 }
1653         }
1654         if (key_tfm)
1655                 (*key_tfm) = NULL;
1656         return 0;
1657 }
1658
1659 /**
1660  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1661  *
1662  * @tfm: set to cached tfm found, or new tfm created
1663  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1664  * @cipher_name: the name of the cipher to search for and/or add
1665  *
1666  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1667  * Searches for cached item first, and creates new if not found.
1668  * Returns 0 on success, non-zero if adding new cipher failed
1669  */
1670 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1671                                                struct mutex **tfm_mutex,
1672                                                char *cipher_name)
1673 {
1674         struct ecryptfs_key_tfm *key_tfm;
1675         int rc = 0;
1676
1677         (*tfm) = NULL;
1678         (*tfm_mutex) = NULL;
1679
1680         mutex_lock(&key_tfm_list_mutex);
1681         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1682                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1683                 if (rc) {
1684                         printk(KERN_ERR "Error adding new key_tfm to list; "
1685                                         "rc = [%d]\n", rc);
1686                         goto out;
1687                 }
1688         }
1689         (*tfm) = key_tfm->key_tfm;
1690         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1691 out:
1692         mutex_unlock(&key_tfm_list_mutex);
1693         return rc;
1694 }
1695
1696 /* 64 characters forming a 6-bit target field */
1697 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1698                                                  "EFGHIJKLMNOPQRST"
1699                                                  "UVWXYZabcdefghij"
1700                                                  "klmnopqrstuvwxyz");
1701
1702 /* We could either offset on every reverse map or just pad some 0x00's
1703  * at the front here */
1704 static const unsigned char filename_rev_map[256] = {
1705         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1706         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1707         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1708         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1709         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1710         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1711         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1712         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1713         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1714         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1715         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1716         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1717         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1718         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1719         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1720         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1721 };
1722
1723 /**
1724  * ecryptfs_encode_for_filename
1725  * @dst: Destination location for encoded filename
1726  * @dst_size: Size of the encoded filename in bytes
1727  * @src: Source location for the filename to encode
1728  * @src_size: Size of the source in bytes
1729  */
1730 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1731                                   unsigned char *src, size_t src_size)
1732 {
1733         size_t num_blocks;
1734         size_t block_num = 0;
1735         size_t dst_offset = 0;
1736         unsigned char last_block[3];
1737
1738         if (src_size == 0) {
1739                 (*dst_size) = 0;
1740                 goto out;
1741         }
1742         num_blocks = (src_size / 3);
1743         if ((src_size % 3) == 0) {
1744                 memcpy(last_block, (&src[src_size - 3]), 3);
1745         } else {
1746                 num_blocks++;
1747                 last_block[2] = 0x00;
1748                 switch (src_size % 3) {
1749                 case 1:
1750                         last_block[0] = src[src_size - 1];
1751                         last_block[1] = 0x00;
1752                         break;
1753                 case 2:
1754                         last_block[0] = src[src_size - 2];
1755                         last_block[1] = src[src_size - 1];
1756                 }
1757         }
1758         (*dst_size) = (num_blocks * 4);
1759         if (!dst)
1760                 goto out;
1761         while (block_num < num_blocks) {
1762                 unsigned char *src_block;
1763                 unsigned char dst_block[4];
1764
1765                 if (block_num == (num_blocks - 1))
1766                         src_block = last_block;
1767                 else
1768                         src_block = &src[block_num * 3];
1769                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1770                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1771                                 | ((src_block[1] >> 4) & 0x0F));
1772                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1773                                 | ((src_block[2] >> 6) & 0x03));
1774                 dst_block[3] = (src_block[2] & 0x3F);
1775                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1776                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1777                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1778                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1779                 block_num++;
1780         }
1781 out:
1782         return;
1783 }
1784
1785 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1786 {
1787         /* Not exact; conservatively long. Every block of 4
1788          * encoded characters decodes into a block of 3
1789          * decoded characters. This segment of code provides
1790          * the caller with the maximum amount of allocated
1791          * space that @dst will need to point to in a
1792          * subsequent call. */
1793         return ((encoded_size + 1) * 3) / 4;
1794 }
1795
1796 /**
1797  * ecryptfs_decode_from_filename
1798  * @dst: If NULL, this function only sets @dst_size and returns. If
1799  *       non-NULL, this function decodes the encoded octets in @src
1800  *       into the memory that @dst points to.
1801  * @dst_size: Set to the size of the decoded string.
1802  * @src: The encoded set of octets to decode.
1803  * @src_size: The size of the encoded set of octets to decode.
1804  */
1805 static void
1806 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1807                               const unsigned char *src, size_t src_size)
1808 {
1809         u8 current_bit_offset = 0;
1810         size_t src_byte_offset = 0;
1811         size_t dst_byte_offset = 0;
1812
1813         if (!dst) {
1814                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1815                 goto out;
1816         }
1817         while (src_byte_offset < src_size) {
1818                 unsigned char src_byte =
1819                                 filename_rev_map[(int)src[src_byte_offset]];
1820
1821                 switch (current_bit_offset) {
1822                 case 0:
1823                         dst[dst_byte_offset] = (src_byte << 2);
1824                         current_bit_offset = 6;
1825                         break;
1826                 case 6:
1827                         dst[dst_byte_offset++] |= (src_byte >> 4);
1828                         dst[dst_byte_offset] = ((src_byte & 0xF)
1829                                                  << 4);
1830                         current_bit_offset = 4;
1831                         break;
1832                 case 4:
1833                         dst[dst_byte_offset++] |= (src_byte >> 2);
1834                         dst[dst_byte_offset] = (src_byte << 6);
1835                         current_bit_offset = 2;
1836                         break;
1837                 case 2:
1838                         dst[dst_byte_offset++] |= (src_byte);
1839                         current_bit_offset = 0;
1840                         break;
1841                 }
1842                 src_byte_offset++;
1843         }
1844         (*dst_size) = dst_byte_offset;
1845 out:
1846         return;
1847 }
1848
1849 /**
1850  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1851  * @encoded_name: The encrypted name
1852  * @encoded_name_size: Length of the encrypted name
1853  * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1854  * @name: The plaintext name
1855  * @name_size: The length of the plaintext name
1856  *
1857  * Encrypts and encodes a filename into something that constitutes a
1858  * valid filename for a filesystem, with printable characters.
1859  *
1860  * We assume that we have a properly initialized crypto context,
1861  * pointed to by crypt_stat->tfm.
1862  *
1863  * Returns zero on success; non-zero on otherwise
1864  */
1865 int ecryptfs_encrypt_and_encode_filename(
1866         char **encoded_name,
1867         size_t *encoded_name_size,
1868         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1869         const char *name, size_t name_size)
1870 {
1871         size_t encoded_name_no_prefix_size;
1872         int rc = 0;
1873
1874         (*encoded_name) = NULL;
1875         (*encoded_name_size) = 0;
1876         if (mount_crypt_stat && (mount_crypt_stat->flags
1877                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1878                 struct ecryptfs_filename *filename;
1879
1880                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1881                 if (!filename) {
1882                         rc = -ENOMEM;
1883                         goto out;
1884                 }
1885                 filename->filename = (char *)name;
1886                 filename->filename_size = name_size;
1887                 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1888                 if (rc) {
1889                         printk(KERN_ERR "%s: Error attempting to encrypt "
1890                                "filename; rc = [%d]\n", __func__, rc);
1891                         kfree(filename);
1892                         goto out;
1893                 }
1894                 ecryptfs_encode_for_filename(
1895                         NULL, &encoded_name_no_prefix_size,
1896                         filename->encrypted_filename,
1897                         filename->encrypted_filename_size);
1898                 if (mount_crypt_stat
1899                         && (mount_crypt_stat->flags
1900                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1901                         (*encoded_name_size) =
1902                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1903                                  + encoded_name_no_prefix_size);
1904                 else
1905                         (*encoded_name_size) =
1906                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1907                                  + encoded_name_no_prefix_size);
1908                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1909                 if (!(*encoded_name)) {
1910                         rc = -ENOMEM;
1911                         kfree(filename->encrypted_filename);
1912                         kfree(filename);
1913                         goto out;
1914                 }
1915                 if (mount_crypt_stat
1916                         && (mount_crypt_stat->flags
1917                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1918                         memcpy((*encoded_name),
1919                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1920                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1921                         ecryptfs_encode_for_filename(
1922                             ((*encoded_name)
1923                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1924                             &encoded_name_no_prefix_size,
1925                             filename->encrypted_filename,
1926                             filename->encrypted_filename_size);
1927                         (*encoded_name_size) =
1928                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1929                                  + encoded_name_no_prefix_size);
1930                         (*encoded_name)[(*encoded_name_size)] = '\0';
1931                 } else {
1932                         rc = -EOPNOTSUPP;
1933                 }
1934                 if (rc) {
1935                         printk(KERN_ERR "%s: Error attempting to encode "
1936                                "encrypted filename; rc = [%d]\n", __func__,
1937                                rc);
1938                         kfree((*encoded_name));
1939                         (*encoded_name) = NULL;
1940                         (*encoded_name_size) = 0;
1941                 }
1942                 kfree(filename->encrypted_filename);
1943                 kfree(filename);
1944         } else {
1945                 rc = ecryptfs_copy_filename(encoded_name,
1946                                             encoded_name_size,
1947                                             name, name_size);
1948         }
1949 out:
1950         return rc;
1951 }
1952
1953 /**
1954  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1955  * @plaintext_name: The plaintext name
1956  * @plaintext_name_size: The plaintext name size
1957  * @sb: Ecryptfs's super_block
1958  * @name: The filename in cipher text
1959  * @name_size: The cipher text name size
1960  *
1961  * Decrypts and decodes the filename.
1962  *
1963  * Returns zero on error; non-zero otherwise
1964  */
1965 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
1966                                          size_t *plaintext_name_size,
1967                                          struct super_block *sb,
1968                                          const char *name, size_t name_size)
1969 {
1970         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1971                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
1972         char *decoded_name;
1973         size_t decoded_name_size;
1974         size_t packet_size;
1975         int rc = 0;
1976
1977         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
1978             !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
1979                 if (is_dot_dotdot(name, name_size)) {
1980                         rc = ecryptfs_copy_filename(plaintext_name,
1981                                                     plaintext_name_size,
1982                                                     name, name_size);
1983                         goto out;
1984                 }
1985
1986                 if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
1987                     strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1988                             ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
1989                         rc = -EINVAL;
1990                         goto out;
1991                 }
1992
1993                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1994                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1995                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
1996                                               name, name_size);
1997                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
1998                 if (!decoded_name) {
1999                         rc = -ENOMEM;
2000                         goto out;
2001                 }
2002                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2003                                               name, name_size);
2004                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2005                                                   plaintext_name_size,
2006                                                   &packet_size,
2007                                                   mount_crypt_stat,
2008                                                   decoded_name,
2009                                                   decoded_name_size);
2010                 if (rc) {
2011                         ecryptfs_printk(KERN_DEBUG,
2012                                         "%s: Could not parse tag 70 packet from filename\n",
2013                                         __func__);
2014                         goto out_free;
2015                 }
2016         } else {
2017                 rc = ecryptfs_copy_filename(plaintext_name,
2018                                             plaintext_name_size,
2019                                             name, name_size);
2020                 goto out;
2021         }
2022 out_free:
2023         kfree(decoded_name);
2024 out:
2025         return rc;
2026 }
2027
2028 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2029
2030 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2031                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2032 {
2033         struct crypto_skcipher *tfm;
2034         struct mutex *tfm_mutex;
2035         size_t cipher_blocksize;
2036         int rc;
2037
2038         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2039                 (*namelen) = lower_namelen;
2040                 return 0;
2041         }
2042
2043         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2044                         mount_crypt_stat->global_default_fn_cipher_name);
2045         if (unlikely(rc)) {
2046                 (*namelen) = 0;
2047                 return rc;
2048         }
2049
2050         mutex_lock(tfm_mutex);
2051         cipher_blocksize = crypto_skcipher_blocksize(tfm);
2052         mutex_unlock(tfm_mutex);
2053
2054         /* Return an exact amount for the common cases */
2055         if (lower_namelen == NAME_MAX
2056             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2057                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2058                 return 0;
2059         }
2060
2061         /* Return a safe estimate for the uncommon cases */
2062         (*namelen) = lower_namelen;
2063         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2064         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2065         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2066         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2067         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2068         /* Worst case is that the filename is padded nearly a full block size */
2069         (*namelen) -= cipher_blocksize - 1;
2070
2071         if ((*namelen) < 0)
2072                 (*namelen) = 0;
2073
2074         return 0;
2075 }