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 <linux/slab.h>
  37 #include <asm/unaligned.h>
  38 #include "ecryptfs_kernel.h"
  39
  40 #define DECRYPT         0
  41 #define ENCRYPT         1
  42
  43 /**
  44  * ecryptfs_to_hex
  45  * @dst: Buffer to take hex character representation of contents of
  46  *       src; must be at least of size (src_size * 2)
  47  * @src: Buffer to be converted to a hex string respresentation
  48  * @src_size: number of bytes to convert
  49  */
  50 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
  51 {
  52         int x;
  53
  54         for (x = 0; x < src_size; x++)
  55                 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
  56 }
  57
  58 /**
  59  * ecryptfs_from_hex
  60  * @dst: Buffer to take the bytes from src hex; must be at least of
  61  *       size (src_size / 2)
  62  * @src: Buffer to be converted from a hex string respresentation to raw value
  63  * @dst_size: size of dst buffer, or number of hex characters pairs to convert
  64  */
  65 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
  66 {
  67         int x;
  68         char tmp[3] = { 0, };
  69
  70         for (x = 0; x < dst_size; x++) {
  71                 tmp[0] = src[x * 2];
  72                 tmp[1] = src[x * 2 + 1];
  73                 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
  74         }
  75 }
  76
  77 /**
  78  * ecryptfs_calculate_md5 - calculates the md5 of @src
  79  * @dst: Pointer to 16 bytes of allocated memory
  80  * @crypt_stat: Pointer to crypt_stat struct for the current inode
  81  * @src: Data to be md5'd
  82  * @len: Length of @src
  83  *
  84  * Uses the allocated crypto context that crypt_stat references to
  85  * generate the MD5 sum of the contents of src.
  86  */
  87 static int ecryptfs_calculate_md5(char *dst,
  88                                   struct ecryptfs_crypt_stat *crypt_stat,
  89                                   char *src, int len)
  90 {
  91         struct scatterlist sg;
  92         struct hash_desc desc = {
  93                 .tfm = crypt_stat->hash_tfm,
  94                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
  95         };
  96         int rc = 0;
  97
  98         mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
  99         sg_init_one(&sg, (u8 *)src, len);
 100         if (!desc.tfm) {
 101                 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
 102                                              CRYPTO_ALG_ASYNC);
 103                 if (IS_ERR(desc.tfm)) {
 104                         rc = PTR_ERR(desc.tfm);
 105                         ecryptfs_printk(KERN_ERR, "Error attempting to "
 106                                         "allocate crypto context; rc = [%d]\n",
 107                                         rc);
 108                         goto out;
 109                 }
 110                 crypt_stat->hash_tfm = desc.tfm;
 111         }
 112         rc = crypto_hash_init(&desc);
 113         if (rc) {
 114                 printk(KERN_ERR
 115                        "%s: Error initializing crypto hash; rc = [%d]\n",
 116                        __func__, rc);
 117                 goto out;
 118         }
 119         rc = crypto_hash_update(&desc, &sg, len);
 120         if (rc) {
 121                 printk(KERN_ERR
 122                        "%s: Error updating crypto hash; rc = [%d]\n",
 123                        __func__, rc);
 124                 goto out;
 125         }
 126         rc = crypto_hash_final(&desc, dst);
 127         if (rc) {
 128                 printk(KERN_ERR
 129                        "%s: Error finalizing crypto hash; rc = [%d]\n",
 130                        __func__, rc);
 131                 goto out;
 132         }
 133 out:
 134         mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
 135         return rc;
 136 }
 137
 138 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
 139                                                   char *cipher_name,
 140                                                   char *chaining_modifier)
 141 {
 142         int cipher_name_len = strlen(cipher_name);
 143         int chaining_modifier_len = strlen(chaining_modifier);
 144         int algified_name_len;
 145         int rc;
 146
 147         algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
 148         (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
 149         if (!(*algified_name)) {
 150                 rc = -ENOMEM;
 151                 goto out;
 152         }
 153         snprintf((*algified_name), algified_name_len, "%s(%s)",
 154                  chaining_modifier, cipher_name);
 155         rc = 0;
 156 out:
 157         return rc;
 158 }
 159
 160 /**
 161  * ecryptfs_derive_iv
 162  * @iv: destination for the derived iv vale
 163  * @crypt_stat: Pointer to crypt_stat struct for the current inode
 164  * @offset: Offset of the extent whose IV we are to derive
 165  *
 166  * Generate the initialization vector from the given root IV and page
 167  * offset.
 168  *
 169  * Returns zero on success; non-zero on error.
 170  */
 171 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
 172                        loff_t offset)
 173 {
 174         int rc = 0;
 175         char dst[MD5_DIGEST_SIZE];
 176         char src[ECRYPTFS_MAX_IV_BYTES + 16];
 177
 178         if (unlikely(ecryptfs_verbosity > 0)) {
 179                 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
 180                 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
 181         }
 182         /* TODO: It is probably secure to just cast the least
 183          * significant bits of the root IV into an unsigned long and
 184          * add the offset to that rather than go through all this
 185          * hashing business. -Halcrow */
 186         memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
 187         memset((src + crypt_stat->iv_bytes), 0, 16);
 188         snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
 189         if (unlikely(ecryptfs_verbosity > 0)) {
 190                 ecryptfs_printk(KERN_DEBUG, "source:\n");
 191                 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
 192         }
 193         rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
 194                                     (crypt_stat->iv_bytes + 16));
 195         if (rc) {
 196                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 197                                 "MD5 while generating IV for a page\n");
 198                 goto out;
 199         }
 200         memcpy(iv, dst, crypt_stat->iv_bytes);
 201         if (unlikely(ecryptfs_verbosity > 0)) {
 202                 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
 203                 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
 204         }
 205 out:
 206         return rc;
 207 }
 208
 209 /**
 210  * ecryptfs_init_crypt_stat
 211  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 212  *
 213  * Initialize the crypt_stat structure.
 214  */
 215 void
 216 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 217 {
 218         memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 219         INIT_LIST_HEAD(&crypt_stat->keysig_list);
 220         mutex_init(&crypt_stat->keysig_list_mutex);
 221         mutex_init(&crypt_stat->cs_mutex);
 222         mutex_init(&crypt_stat->cs_tfm_mutex);
 223         mutex_init(&crypt_stat->cs_hash_tfm_mutex);
 224         crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
 225 }
 226
 227 /**
 228  * ecryptfs_destroy_crypt_stat
 229  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 230  *
 231  * Releases all memory associated with a crypt_stat struct.
 232  */
 233 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 234 {
 235         struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 236
 237         if (crypt_stat->tfm)
 238                 crypto_free_ablkcipher(crypt_stat->tfm);
 239         if (crypt_stat->hash_tfm)
 240                 crypto_free_hash(crypt_stat->hash_tfm);
 241         list_for_each_entry_safe(key_sig, key_sig_tmp,
 242                                  &crypt_stat->keysig_list, crypt_stat_list) {
 243                 list_del(&key_sig->crypt_stat_list);
 244                 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
 245         }
 246         memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
 247 }
 248
 249 void ecryptfs_destroy_mount_crypt_stat(
 250         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 251 {
 252         struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
 253
 254         if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
 255                 return;
 256         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 257         list_for_each_entry_safe(auth_tok, auth_tok_tmp,
 258                                  &mount_crypt_stat->global_auth_tok_list,
 259                                  mount_crypt_stat_list) {
 260                 list_del(&auth_tok->mount_crypt_stat_list);
 261                 if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 262                         key_put(auth_tok->global_auth_tok_key);
 263                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 264         }
 265         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 266         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 267 }
 268
 269 /**
 270  * virt_to_scatterlist
 271  * @addr: Virtual address
 272  * @size: Size of data; should be an even multiple of the block size
 273  * @sg: Pointer to scatterlist array; set to NULL to obtain only
 274  *      the number of scatterlist structs required in array
 275  * @sg_size: Max array size
 276  *
 277  * Fills in a scatterlist array with page references for a passed
 278  * virtual address.
 279  *
 280  * Returns the number of scatterlist structs in array used
 281  */
 282 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 283                         int sg_size)
 284 {
 285         int i = 0;
 286         struct page *pg;
 287         int offset;
 288         int remainder_of_page;
 289
 290         sg_init_table(sg, sg_size);
 291
 292         while (size > 0 && i < sg_size) {
 293                 pg = virt_to_page(addr);
 294                 offset = offset_in_page(addr);
 295                 sg_set_page(&sg[i], pg, 0, offset);
 296                 remainder_of_page = PAGE_CACHE_SIZE - offset;
 297                 if (size >= remainder_of_page) {
 298                         sg[i].length = remainder_of_page;
 299                         addr += remainder_of_page;
 300                         size -= remainder_of_page;
 301                 } else {
 302                         sg[i].length = size;
 303                         addr += size;
 304                         size = 0;
 305                 }
 306                 i++;
 307         }
 308         if (size > 0)
 309                 return -ENOMEM;
 310         return i;
 311 }
 312
 313 struct extent_crypt_result {
 314         struct completion completion;
 315         int rc;
 316 };
 317
 318 static void extent_crypt_complete(struct crypto_async_request *req, int rc)
 319 {
 320         struct extent_crypt_result *ecr = req->data;
 321
 322         if (rc == -EINPROGRESS)
 323                 return;
 324
 325         ecr->rc = rc;
 326         complete(&ecr->completion);
 327 }
 328
 329 /**
 330  * crypt_scatterlist
 331  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 332  * @dst_sg: Destination of the data after performing the crypto operation
 333  * @src_sg: Data to be encrypted or decrypted
 334  * @size: Length of data
 335  * @iv: IV to use
 336  * @op: ENCRYPT or DECRYPT to indicate the desired operation
 337  *
 338  * Returns the number of bytes encrypted or decrypted; negative value on error
 339  */
 340 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 341                              struct scatterlist *dst_sg,
 342                              struct scatterlist *src_sg, int size,
 343                              unsigned char *iv, int op)
 344 {
 345         struct ablkcipher_request *req = NULL;
 346         struct extent_crypt_result ecr;
 347         int rc = 0;
 348
 349         BUG_ON(!crypt_stat || !crypt_stat->tfm
 350                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 351         if (unlikely(ecryptfs_verbosity > 0)) {
 352                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 353                                 crypt_stat->key_size);
 354                 ecryptfs_dump_hex(crypt_stat->key,
 355                                   crypt_stat->key_size);
 356         }
 357
 358         init_completion(&ecr.completion);
 359
 360         mutex_lock(&crypt_stat->cs_tfm_mutex);
 361         req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
 362         if (!req) {
 363                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 364                 rc = -ENOMEM;
 365                 goto out;
 366         }
 367
 368         ablkcipher_request_set_callback(req,
 369                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 370                         extent_crypt_complete, &ecr);
 371         /* Consider doing this once, when the file is opened */
 372         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 373                 rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 374                                               crypt_stat->key_size);
 375                 if (rc) {
 376                         ecryptfs_printk(KERN_ERR,
 377                                         "Error setting key; rc = [%d]\n",
 378                                         rc);
 379                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 380                         rc = -EINVAL;
 381                         goto out;
 382                 }
 383                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
 384         }
 385         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 386         ablkcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 387         rc = op == ENCRYPT ? crypto_ablkcipher_encrypt(req) :
 388                              crypto_ablkcipher_decrypt(req);
 389         if (rc == -EINPROGRESS || rc == -EBUSY) {
 390                 struct extent_crypt_result *ecr = req->base.data;
 391
 392                 wait_for_completion(&ecr->completion);
 393                 rc = ecr->rc;
 394                 reinit_completion(&ecr->completion);
 395         }
 396 out:
 397         ablkcipher_request_free(req);
 398         return rc;
 399 }
 400
 401 /**
 402  * lower_offset_for_page
 403  *
 404  * Convert an eCryptfs page index into a lower byte offset
 405  */
 406 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 407                                     struct page *page)
 408 {
 409         return ecryptfs_lower_header_size(crypt_stat) +
 410                ((loff_t)page->index << PAGE_CACHE_SHIFT);
 411 }
 412
 413 /**
 414  * crypt_extent
 415  * @crypt_stat: crypt_stat containing cryptographic context for the
 416  *              encryption operation
 417  * @dst_page: The page to write the result into
 418  * @src_page: The page to read from
 419  * @extent_offset: Page extent offset for use in generating IV
 420  * @op: ENCRYPT or DECRYPT to indicate the desired operation
 421  *
 422  * Encrypts or decrypts one extent of data.
 423  *
 424  * Return zero on success; non-zero otherwise
 425  */
 426 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 427                         struct page *dst_page,
 428                         struct page *src_page,
 429                         unsigned long extent_offset, int op)
 430 {
 431         pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
 432         loff_t extent_base;
 433         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 434         struct scatterlist src_sg, dst_sg;
 435         size_t extent_size = crypt_stat->extent_size;
 436         int rc;
 437
 438         extent_base = (((loff_t)page_index) * (PAGE_CACHE_SIZE / extent_size));
 439         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 440                                 (extent_base + extent_offset));
 441         if (rc) {
 442                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 443                         "extent [0x%.16llx]; rc = [%d]\n",
 444                         (unsigned long long)(extent_base + extent_offset), rc);
 445                 goto out;
 446         }
 447
 448         sg_init_table(&src_sg, 1);
 449         sg_init_table(&dst_sg, 1);
 450
 451         sg_set_page(&src_sg, src_page, extent_size,
 452                     extent_offset * extent_size);
 453         sg_set_page(&dst_sg, dst_page, extent_size,
 454                     extent_offset * extent_size);
 455
 456         rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 457                                extent_iv, op);
 458         if (rc < 0) {
 459                 printk(KERN_ERR "%s: Error attempting to crypt page with "
 460                        "page_index = [%ld], extent_offset = [%ld]; "
 461                        "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 462                 goto out;
 463         }
 464         rc = 0;
 465 out:
 466         return rc;
 467 }
 468
 469 /**
 470  * ecryptfs_encrypt_page
 471  * @page: Page mapped from the eCryptfs inode for the file; contains
 472  *        decrypted content that needs to be encrypted (to a temporary
 473  *        page; not in place) and written out to the lower file
 474  *
 475  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 476  * that eCryptfs pages may straddle the lower pages -- for instance,
 477  * if the file was created on a machine with an 8K page size
 478  * (resulting in an 8K header), and then the file is copied onto a
 479  * host with a 32K page size, then when reading page 0 of the eCryptfs
 480  * file, 24K of page 0 of the lower file will be read and decrypted,
 481  * and then 8K of page 1 of the lower file will be read and decrypted.
 482  *
 483  * Returns zero on success; negative on error
 484  */
 485 int ecryptfs_encrypt_page(struct page *page)
 486 {
 487         struct inode *ecryptfs_inode;
 488         struct ecryptfs_crypt_stat *crypt_stat;
 489         char *enc_extent_virt;
 490         struct page *enc_extent_page = NULL;
 491         loff_t extent_offset;
 492         loff_t lower_offset;
 493         int rc = 0;
 494
 495         ecryptfs_inode = page->mapping->host;
 496         crypt_stat =
 497                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 498         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 499         enc_extent_page = alloc_page(GFP_USER);
 500         if (!enc_extent_page) {
 501                 rc = -ENOMEM;
 502                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 503                                 "encrypted extent\n");
 504                 goto out;
 505         }
 506
 507         for (extent_offset = 0;
 508              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 509              extent_offset++) {
 510                 rc = crypt_extent(crypt_stat, enc_extent_page, page,
 511                                   extent_offset, ENCRYPT);
 512                 if (rc) {
 513                         printk(KERN_ERR "%s: Error encrypting extent; "
 514                                "rc = [%d]\n", __func__, rc);
 515                         goto out;
 516                 }
 517         }
 518
 519         lower_offset = lower_offset_for_page(crypt_stat, page);
 520         enc_extent_virt = kmap(enc_extent_page);
 521         rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 522                                   PAGE_CACHE_SIZE);
 523         kunmap(enc_extent_page);
 524         if (rc < 0) {
 525                 ecryptfs_printk(KERN_ERR,
 526                         "Error attempting to write lower page; rc = [%d]\n",
 527                         rc);
 528                 goto out;
 529         }
 530         rc = 0;
 531 out:
 532         if (enc_extent_page) {
 533                 __free_page(enc_extent_page);
 534         }
 535         return rc;
 536 }
 537
 538 /**
 539  * ecryptfs_decrypt_page
 540  * @page: Page mapped from the eCryptfs inode for the file; data read
 541  *        and decrypted from the lower file will be written into this
 542  *        page
 543  *
 544  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 545  * that eCryptfs pages may straddle the lower pages -- for instance,
 546  * if the file was created on a machine with an 8K page size
 547  * (resulting in an 8K header), and then the file is copied onto a
 548  * host with a 32K page size, then when reading page 0 of the eCryptfs
 549  * file, 24K of page 0 of the lower file will be read and decrypted,
 550  * and then 8K of page 1 of the lower file will be read and decrypted.
 551  *
 552  * Returns zero on success; negative on error
 553  */
 554 int ecryptfs_decrypt_page(struct page *page)
 555 {
 556         struct inode *ecryptfs_inode;
 557         struct ecryptfs_crypt_stat *crypt_stat;
 558         char *page_virt;
 559         unsigned long extent_offset;
 560         loff_t lower_offset;
 561         int rc = 0;
 562
 563         ecryptfs_inode = page->mapping->host;
 564         crypt_stat =
 565                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 566         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 567
 568         lower_offset = lower_offset_for_page(crypt_stat, page);
 569         page_virt = kmap(page);
 570         rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_CACHE_SIZE,
 571                                  ecryptfs_inode);
 572         kunmap(page);
 573         if (rc < 0) {
 574                 ecryptfs_printk(KERN_ERR,
 575                         "Error attempting to read lower page; rc = [%d]\n",
 576                         rc);
 577                 goto out;
 578         }
 579
 580         for (extent_offset = 0;
 581              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 582              extent_offset++) {
 583                 rc = crypt_extent(crypt_stat, page, page,
 584                                   extent_offset, DECRYPT);
 585                 if (rc) {
 586                         printk(KERN_ERR "%s: Error encrypting extent; "
 587                                "rc = [%d]\n", __func__, rc);
 588                         goto out;
 589                 }
 590         }
 591 out:
 592         return rc;
 593 }
 594
 595 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 596
 597 /**
 598  * ecryptfs_init_crypt_ctx
 599  * @crypt_stat: Uninitialized crypt stats structure
 600  *
 601  * Initialize the crypto context.
 602  *
 603  * TODO: Performance: Keep a cache of initialized cipher contexts;
 604  * only init if needed
 605  */
 606 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 607 {
 608         char *full_alg_name;
 609         int rc = -EINVAL;
 610
 611         ecryptfs_printk(KERN_DEBUG,
 612                         "Initializing cipher [%s]; strlen = [%d]; "
 613                         "key_size_bits = [%zd]\n",
 614                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 615                         crypt_stat->key_size << 3);
 616         mutex_lock(&crypt_stat->cs_tfm_mutex);
 617         if (crypt_stat->tfm) {
 618                 rc = 0;
 619                 goto out_unlock;
 620         }
 621         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 622                                                     crypt_stat->cipher, "cbc");
 623         if (rc)
 624                 goto out_unlock;
 625         crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
 626         if (IS_ERR(crypt_stat->tfm)) {
 627                 rc = PTR_ERR(crypt_stat->tfm);
 628                 crypt_stat->tfm = NULL;
 629                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 630                                 "Error initializing cipher [%s]\n",
 631                                 full_alg_name);
 632                 goto out_free;
 633         }
 634         crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 635         rc = 0;
 636 out_free:
 637         kfree(full_alg_name);
 638 out_unlock:
 639         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 640         return rc;
 641 }
 642
 643 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 644 {
 645         int extent_size_tmp;
 646
 647         crypt_stat->extent_mask = 0xFFFFFFFF;
 648         crypt_stat->extent_shift = 0;
 649         if (crypt_stat->extent_size == 0)
 650                 return;
 651         extent_size_tmp = crypt_stat->extent_size;
 652         while ((extent_size_tmp & 0x01) == 0) {
 653                 extent_size_tmp >>= 1;
 654                 crypt_stat->extent_mask <<= 1;
 655                 crypt_stat->extent_shift++;
 656         }
 657 }
 658
 659 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 660 {
 661         /* Default values; may be overwritten as we are parsing the
 662          * packets. */
 663         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 664         set_extent_mask_and_shift(crypt_stat);
 665         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 666         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 667                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 668         else {
 669                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 670                         crypt_stat->metadata_size =
 671                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 672                 else
 673                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
 674         }
 675 }
 676
 677 /**
 678  * ecryptfs_compute_root_iv
 679  * @crypt_stats
 680  *
 681  * On error, sets the root IV to all 0's.
 682  */
 683 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 684 {
 685         int rc = 0;
 686         char dst[MD5_DIGEST_SIZE];
 687
 688         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 689         BUG_ON(crypt_stat->iv_bytes <= 0);
 690         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 691                 rc = -EINVAL;
 692                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 693                                 "cannot generate root IV\n");
 694                 goto out;
 695         }
 696         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 697                                     crypt_stat->key_size);
 698         if (rc) {
 699                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 700                                 "MD5 while generating root IV\n");
 701                 goto out;
 702         }
 703         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 704 out:
 705         if (rc) {
 706                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 707                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 708         }
 709         return rc;
 710 }
 711
 712 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 713 {
 714         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 715         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 716         ecryptfs_compute_root_iv(crypt_stat);
 717         if (unlikely(ecryptfs_verbosity > 0)) {
 718                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 719                 ecryptfs_dump_hex(crypt_stat->key,
 720                                   crypt_stat->key_size);
 721         }
 722 }
 723
 724 /**
 725  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 726  * @crypt_stat: The inode's cryptographic context
 727  * @mount_crypt_stat: The mount point's cryptographic context
 728  *
 729  * This function propagates the mount-wide flags to individual inode
 730  * flags.
 731  */
 732 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 733         struct ecryptfs_crypt_stat *crypt_stat,
 734         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 735 {
 736         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 737                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 738         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 739                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 740         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 741                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 742                 if (mount_crypt_stat->flags
 743                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 744                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 745                 else if (mount_crypt_stat->flags
 746                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 747                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 748         }
 749 }
 750
 751 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 752         struct ecryptfs_crypt_stat *crypt_stat,
 753         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 754 {
 755         struct ecryptfs_global_auth_tok *global_auth_tok;
 756         int rc = 0;
 757
 758         mutex_lock(&crypt_stat->keysig_list_mutex);
 759         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 760
 761         list_for_each_entry(global_auth_tok,
 762                             &mount_crypt_stat->global_auth_tok_list,
 763                             mount_crypt_stat_list) {
 764                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 765                         continue;
 766                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 767                 if (rc) {
 768                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 769                         goto out;
 770                 }
 771         }
 772
 773 out:
 774         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 775         mutex_unlock(&crypt_stat->keysig_list_mutex);
 776         return rc;
 777 }
 778
 779 /**
 780  * ecryptfs_set_default_crypt_stat_vals
 781  * @crypt_stat: The inode's cryptographic context
 782  * @mount_crypt_stat: The mount point's cryptographic context
 783  *
 784  * Default values in the event that policy does not override them.
 785  */
 786 static void ecryptfs_set_default_crypt_stat_vals(
 787         struct ecryptfs_crypt_stat *crypt_stat,
 788         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 789 {
 790         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 791                                                       mount_crypt_stat);
 792         ecryptfs_set_default_sizes(crypt_stat);
 793         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 794         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 795         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 796         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 797         crypt_stat->mount_crypt_stat = mount_crypt_stat;
 798 }
 799
 800 /**
 801  * ecryptfs_new_file_context
 802  * @ecryptfs_inode: The eCryptfs inode
 803  *
 804  * If the crypto context for the file has not yet been established,
 805  * this is where we do that.  Establishing a new crypto context
 806  * involves the following decisions:
 807  *  - What cipher to use?
 808  *  - What set of authentication tokens to use?
 809  * Here we just worry about getting enough information into the
 810  * authentication tokens so that we know that they are available.
 811  * We associate the available authentication tokens with the new file
 812  * via the set of signatures in the crypt_stat struct.  Later, when
 813  * the headers are actually written out, we may again defer to
 814  * userspace to perform the encryption of the session key; for the
 815  * foreseeable future, this will be the case with public key packets.
 816  *
 817  * Returns zero on success; non-zero otherwise
 818  */
 819 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 820 {
 821         struct ecryptfs_crypt_stat *crypt_stat =
 822             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 823         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 824             &ecryptfs_superblock_to_private(
 825                     ecryptfs_inode->i_sb)->mount_crypt_stat;
 826         int cipher_name_len;
 827         int rc = 0;
 828
 829         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 830         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 831         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 832                                                       mount_crypt_stat);
 833         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 834                                                          mount_crypt_stat);
 835         if (rc) {
 836                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 837                        "to the inode key sigs; rc = [%d]\n", rc);
 838                 goto out;
 839         }
 840         cipher_name_len =
 841                 strlen(mount_crypt_stat->global_default_cipher_name);
 842         memcpy(crypt_stat->cipher,
 843                mount_crypt_stat->global_default_cipher_name,
 844                cipher_name_len);
 845         crypt_stat->cipher[cipher_name_len] = '\0';
 846         crypt_stat->key_size =
 847                 mount_crypt_stat->global_default_cipher_key_size;
 848         ecryptfs_generate_new_key(crypt_stat);
 849         rc = ecryptfs_init_crypt_ctx(crypt_stat);
 850         if (rc)
 851                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 852                                 "context for cipher [%s]: rc = [%d]\n",
 853                                 crypt_stat->cipher, rc);
 854 out:
 855         return rc;
 856 }
 857
 858 /**
 859  * ecryptfs_validate_marker - check for the ecryptfs marker
 860  * @data: The data block in which to check
 861  *
 862  * Returns zero if marker found; -EINVAL if not found
 863  */
 864 static int ecryptfs_validate_marker(char *data)
 865 {
 866         u32 m_1, m_2;
 867
 868         m_1 = get_unaligned_be32(data);
 869         m_2 = get_unaligned_be32(data + 4);
 870         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 871                 return 0;
 872         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
 873                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
 874                         MAGIC_ECRYPTFS_MARKER);
 875         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
 876                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
 877         return -EINVAL;
 878 }
 879
 880 struct ecryptfs_flag_map_elem {
 881         u32 file_flag;
 882         u32 local_flag;
 883 };
 884
 885 /* Add support for additional flags by adding elements here. */
 886 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 887         {0x00000001, ECRYPTFS_ENABLE_HMAC},
 888         {0x00000002, ECRYPTFS_ENCRYPTED},
 889         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
 890         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 891 };
 892
 893 /**
 894  * ecryptfs_process_flags
 895  * @crypt_stat: The cryptographic context
 896  * @page_virt: Source data to be parsed
 897  * @bytes_read: Updated with the number of bytes read
 898  *
 899  * Returns zero on success; non-zero if the flag set is invalid
 900  */
 901 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
 902                                   char *page_virt, int *bytes_read)
 903 {
 904         int rc = 0;
 905         int i;
 906         u32 flags;
 907
 908         flags = get_unaligned_be32(page_virt);
 909         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 910                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
 911                 if (flags & ecryptfs_flag_map[i].file_flag) {
 912                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
 913                 } else
 914                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
 915         /* Version is in top 8 bits of the 32-bit flag vector */
 916         crypt_stat->file_version = ((flags >> 24) & 0xFF);
 917         (*bytes_read) = 4;
 918         return rc;
 919 }
 920
 921 /**
 922  * write_ecryptfs_marker
 923  * @page_virt: The pointer to in a page to begin writing the marker
 924  * @written: Number of bytes written
 925  *
 926  * Marker = 0x3c81b7f5
 927  */
 928 static void write_ecryptfs_marker(char *page_virt, size_t *written)
 929 {
 930         u32 m_1, m_2;
 931
 932         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 933         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 934         put_unaligned_be32(m_1, page_virt);
 935         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 936         put_unaligned_be32(m_2, page_virt);
 937         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 938 }
 939
 940 void ecryptfs_write_crypt_stat_flags(char *page_virt,
 941                                      struct ecryptfs_crypt_stat *crypt_stat,
 942                                      size_t *written)
 943 {
 944         u32 flags = 0;
 945         int i;
 946
 947         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 948                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
 949                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
 950                         flags |= ecryptfs_flag_map[i].file_flag;
 951         /* Version is in top 8 bits of the 32-bit flag vector */
 952         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
 953         put_unaligned_be32(flags, page_virt);
 954         (*written) = 4;
 955 }
 956
 957 struct ecryptfs_cipher_code_str_map_elem {
 958         char cipher_str[16];
 959         u8 cipher_code;
 960 };
 961
 962 /* Add support for additional ciphers by adding elements here. The
 963  * cipher_code is whatever OpenPGP applicatoins use to identify the
 964  * ciphers. List in order of probability. */
 965 static struct ecryptfs_cipher_code_str_map_elem
 966 ecryptfs_cipher_code_str_map[] = {
 967         {"aes",RFC2440_CIPHER_AES_128 },
 968         {"blowfish", RFC2440_CIPHER_BLOWFISH},
 969         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
 970         {"cast5", RFC2440_CIPHER_CAST_5},
 971         {"twofish", RFC2440_CIPHER_TWOFISH},
 972         {"cast6", RFC2440_CIPHER_CAST_6},
 973         {"aes", RFC2440_CIPHER_AES_192},
 974         {"aes", RFC2440_CIPHER_AES_256}
 975 };
 976
 977 /**
 978  * ecryptfs_code_for_cipher_string
 979  * @cipher_name: The string alias for the cipher
 980  * @key_bytes: Length of key in bytes; used for AES code selection
 981  *
 982  * Returns zero on no match, or the cipher code on match
 983  */
 984 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 985 {
 986         int i;
 987         u8 code = 0;
 988         struct ecryptfs_cipher_code_str_map_elem *map =
 989                 ecryptfs_cipher_code_str_map;
 990
 991         if (strcmp(cipher_name, "aes") == 0) {
 992                 switch (key_bytes) {
 993                 case 16:
 994                         code = RFC2440_CIPHER_AES_128;
 995                         break;
 996                 case 24:
 997                         code = RFC2440_CIPHER_AES_192;
 998                         break;
 999                 case 32:
1000                         code = RFC2440_CIPHER_AES_256;
1001                 }
1002         } else {
1003                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1004                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1005                                 code = map[i].cipher_code;
1006                                 break;
1007                         }
1008         }
1009         return code;
1010 }
1011
1012 /**
1013  * ecryptfs_cipher_code_to_string
1014  * @str: Destination to write out the cipher name
1015  * @cipher_code: The code to convert to cipher name string
1016  *
1017  * Returns zero on success
1018  */
1019 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1020 {
1021         int rc = 0;
1022         int i;
1023
1024         str[0] = '\0';
1025         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1026                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1027                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1028         if (str[0] == '\0') {
1029                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1030                                 "[%d]\n", cipher_code);
1031                 rc = -EINVAL;
1032         }
1033         return rc;
1034 }
1035
1036 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1037 {
1038         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1039         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1040         int rc;
1041
1042         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1043                                  inode);
1044         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1045                 return rc >= 0 ? -EINVAL : rc;
1046         rc = ecryptfs_validate_marker(marker);
1047         if (!rc)
1048                 ecryptfs_i_size_init(file_size, inode);
1049         return rc;
1050 }
1051
1052 void
1053 ecryptfs_write_header_metadata(char *virt,
1054                                struct ecryptfs_crypt_stat *crypt_stat,
1055                                size_t *written)
1056 {
1057         u32 header_extent_size;
1058         u16 num_header_extents_at_front;
1059
1060         header_extent_size = (u32)crypt_stat->extent_size;
1061         num_header_extents_at_front =
1062                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1063         put_unaligned_be32(header_extent_size, virt);
1064         virt += 4;
1065         put_unaligned_be16(num_header_extents_at_front, virt);
1066         (*written) = 6;
1067 }
1068
1069 struct kmem_cache *ecryptfs_header_cache;
1070
1071 /**
1072  * ecryptfs_write_headers_virt
1073  * @page_virt: The virtual address to write the headers to
1074  * @max: The size of memory allocated at page_virt
1075  * @size: Set to the number of bytes written by this function
1076  * @crypt_stat: The cryptographic context
1077  * @ecryptfs_dentry: The eCryptfs dentry
1078  *
1079  * Format version: 1
1080  *
1081  *   Header Extent:
1082  *     Octets 0-7:        Unencrypted file size (big-endian)
1083  *     Octets 8-15:       eCryptfs special marker
1084  *     Octets 16-19:      Flags
1085  *      Octet 16:         File format version number (between 0 and 255)
1086  *      Octets 17-18:     Reserved
1087  *      Octet 19:         Bit 1 (lsb): Reserved
1088  *                        Bit 2: Encrypted?
1089  *                        Bits 3-8: Reserved
1090  *     Octets 20-23:      Header extent size (big-endian)
1091  *     Octets 24-25:      Number of header extents at front of file
1092  *                        (big-endian)
1093  *     Octet  26:         Begin RFC 2440 authentication token packet set
1094  *   Data Extent 0:
1095  *     Lower data (CBC encrypted)
1096  *   Data Extent 1:
1097  *     Lower data (CBC encrypted)
1098  *   ...
1099  *
1100  * Returns zero on success
1101  */
1102 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1103                                        size_t *size,
1104                                        struct ecryptfs_crypt_stat *crypt_stat,
1105                                        struct dentry *ecryptfs_dentry)
1106 {
1107         int rc;
1108         size_t written;
1109         size_t offset;
1110
1111         offset = ECRYPTFS_FILE_SIZE_BYTES;
1112         write_ecryptfs_marker((page_virt + offset), &written);
1113         offset += written;
1114         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1115                                         &written);
1116         offset += written;
1117         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1118                                        &written);
1119         offset += written;
1120         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1121                                               ecryptfs_dentry, &written,
1122                                               max - offset);
1123         if (rc)
1124                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1125                                 "set; rc = [%d]\n", rc);
1126         if (size) {
1127                 offset += written;
1128                 *size = offset;
1129         }
1130         return rc;
1131 }
1132
1133 static int
1134 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1135                                     char *virt, size_t virt_len)
1136 {
1137         int rc;
1138
1139         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1140                                   0, virt_len);
1141         if (rc < 0)
1142                 printk(KERN_ERR "%s: Error attempting to write header "
1143                        "information to lower file; rc = [%d]\n", __func__, rc);
1144         else
1145                 rc = 0;
1146         return rc;
1147 }
1148
1149 static int
1150 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1151                                  char *page_virt, size_t size)
1152 {
1153         int rc;
1154
1155         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1156                                size, 0);
1157         return rc;
1158 }
1159
1160 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1161                                                unsigned int order)
1162 {
1163         struct page *page;
1164
1165         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1166         if (page)
1167                 return (unsigned long) page_address(page);
1168         return 0;
1169 }
1170
1171 /**
1172  * ecryptfs_write_metadata
1173  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1174  * @ecryptfs_inode: The newly created eCryptfs inode
1175  *
1176  * Write the file headers out.  This will likely involve a userspace
1177  * callout, in which the session key is encrypted with one or more
1178  * public keys and/or the passphrase necessary to do the encryption is
1179  * retrieved via a prompt.  Exactly what happens at this point should
1180  * be policy-dependent.
1181  *
1182  * Returns zero on success; non-zero on error
1183  */
1184 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1185                             struct inode *ecryptfs_inode)
1186 {
1187         struct ecryptfs_crypt_stat *crypt_stat =
1188                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1189         unsigned int order;
1190         char *virt;
1191         size_t virt_len;
1192         size_t size = 0;
1193         int rc = 0;
1194
1195         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1196                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1197                         printk(KERN_ERR "Key is invalid; bailing out\n");
1198                         rc = -EINVAL;
1199                         goto out;
1200                 }
1201         } else {
1202                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1203                        __func__);
1204                 rc = -EINVAL;
1205                 goto out;
1206         }
1207         virt_len = crypt_stat->metadata_size;
1208         order = get_order(virt_len);
1209         /* Released in this function */
1210         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1211         if (!virt) {
1212                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1213                 rc = -ENOMEM;
1214                 goto out;
1215         }
1216         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1217         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1218                                          ecryptfs_dentry);
1219         if (unlikely(rc)) {
1220                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1221                        __func__, rc);
1222                 goto out_free;
1223         }
1224         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1225                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1226                                                       size);
1227         else
1228                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1229                                                          virt_len);
1230         if (rc) {
1231                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1232                        "rc = [%d]\n", __func__, rc);
1233                 goto out_free;
1234         }
1235 out_free:
1236         free_pages((unsigned long)virt, order);
1237 out:
1238         return rc;
1239 }
1240
1241 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1242 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1243 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1244                                  char *virt, int *bytes_read,
1245                                  int validate_header_size)
1246 {
1247         int rc = 0;
1248         u32 header_extent_size;
1249         u16 num_header_extents_at_front;
1250
1251         header_extent_size = get_unaligned_be32(virt);
1252         virt += sizeof(__be32);
1253         num_header_extents_at_front = get_unaligned_be16(virt);
1254         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1255                                      * (size_t)header_extent_size));
1256         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1257         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1258             && (crypt_stat->metadata_size
1259                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1260                 rc = -EINVAL;
1261                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1262                        crypt_stat->metadata_size);
1263         }
1264         return rc;
1265 }
1266
1267 /**
1268  * set_default_header_data
1269  * @crypt_stat: The cryptographic context
1270  *
1271  * For version 0 file format; this function is only for backwards
1272  * compatibility for files created with the prior versions of
1273  * eCryptfs.
1274  */
1275 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1276 {
1277         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1278 }
1279
1280 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1281 {
1282         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1283         struct ecryptfs_crypt_stat *crypt_stat;
1284         u64 file_size;
1285
1286         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1287         mount_crypt_stat =
1288                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1289         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1290                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1291                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1292                         file_size += crypt_stat->metadata_size;
1293         } else
1294                 file_size = get_unaligned_be64(page_virt);
1295         i_size_write(inode, (loff_t)file_size);
1296         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1297 }
1298
1299 /**
1300  * ecryptfs_read_headers_virt
1301  * @page_virt: The virtual address into which to read the headers
1302  * @crypt_stat: The cryptographic context
1303  * @ecryptfs_dentry: The eCryptfs dentry
1304  * @validate_header_size: Whether to validate the header size while reading
1305  *
1306  * Read/parse the header data. The header format is detailed in the
1307  * comment block for the ecryptfs_write_headers_virt() function.
1308  *
1309  * Returns zero on success
1310  */
1311 static int ecryptfs_read_headers_virt(char *page_virt,
1312                                       struct ecryptfs_crypt_stat *crypt_stat,
1313                                       struct dentry *ecryptfs_dentry,
1314                                       int validate_header_size)
1315 {
1316         int rc = 0;
1317         int offset;
1318         int bytes_read;
1319
1320         ecryptfs_set_default_sizes(crypt_stat);
1321         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1322                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1323         offset = ECRYPTFS_FILE_SIZE_BYTES;
1324         rc = ecryptfs_validate_marker(page_virt + offset);
1325         if (rc)
1326                 goto out;
1327         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1328                 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1329         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1330         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1331                                     &bytes_read);
1332         if (rc) {
1333                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1334                 goto out;
1335         }
1336         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1337                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1338                                 "file version [%d] is supported by this "
1339                                 "version of eCryptfs\n",
1340                                 crypt_stat->file_version,
1341                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1342                 rc = -EINVAL;
1343                 goto out;
1344         }
1345         offset += bytes_read;
1346         if (crypt_stat->file_version >= 1) {
1347                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1348                                            &bytes_read, validate_header_size);
1349                 if (rc) {
1350                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1351                                         "metadata; rc = [%d]\n", rc);
1352                 }
1353                 offset += bytes_read;
1354         } else
1355                 set_default_header_data(crypt_stat);
1356         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1357                                        ecryptfs_dentry);
1358 out:
1359         return rc;
1360 }
1361
1362 /**
1363  * ecryptfs_read_xattr_region
1364  * @page_virt: The vitual address into which to read the xattr data
1365  * @ecryptfs_inode: The eCryptfs inode
1366  *
1367  * Attempts to read the crypto metadata from the extended attribute
1368  * region of the lower file.
1369  *
1370  * Returns zero on success; non-zero on error
1371  */
1372 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1373 {
1374         struct dentry *lower_dentry =
1375                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1376         ssize_t size;
1377         int rc = 0;
1378
1379         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1380                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1381         if (size < 0) {
1382                 if (unlikely(ecryptfs_verbosity > 0))
1383                         printk(KERN_INFO "Error attempting to read the [%s] "
1384                                "xattr from the lower file; return value = "
1385                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1386                 rc = -EINVAL;
1387                 goto out;
1388         }
1389 out:
1390         return rc;
1391 }
1392
1393 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1394                                             struct inode *inode)
1395 {
1396         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1397         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1398         int rc;
1399
1400         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1401                                      ECRYPTFS_XATTR_NAME, file_size,
1402                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1403         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1404                 return rc >= 0 ? -EINVAL : rc;
1405         rc = ecryptfs_validate_marker(marker);
1406         if (!rc)
1407                 ecryptfs_i_size_init(file_size, inode);
1408         return rc;
1409 }
1410
1411 /**
1412  * ecryptfs_read_metadata
1413  *
1414  * Common entry point for reading file metadata. From here, we could
1415  * retrieve the header information from the header region of the file,
1416  * the xattr region of the file, or some other repostory that is
1417  * stored separately from the file itself. The current implementation
1418  * supports retrieving the metadata information from the file contents
1419  * and from the xattr region.
1420  *
1421  * Returns zero if valid headers found and parsed; non-zero otherwise
1422  */
1423 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1424 {
1425         int rc;
1426         char *page_virt;
1427         struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1428         struct ecryptfs_crypt_stat *crypt_stat =
1429             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1430         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1431                 &ecryptfs_superblock_to_private(
1432                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1433
1434         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1435                                                       mount_crypt_stat);
1436         /* Read the first page from the underlying file */
1437         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1438         if (!page_virt) {
1439                 rc = -ENOMEM;
1440                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1441                        __func__);
1442                 goto out;
1443         }
1444         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1445                                  ecryptfs_inode);
1446         if (rc >= 0)
1447                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1448                                                 ecryptfs_dentry,
1449                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1450         if (rc) {
1451                 /* metadata is not in the file header, so try xattrs */
1452                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1453                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1454                 if (rc) {
1455                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1456                                "file header region or xattr region, inode %lu\n",
1457                                 ecryptfs_inode->i_ino);
1458                         rc = -EINVAL;
1459                         goto out;
1460                 }
1461                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1462                                                 ecryptfs_dentry,
1463                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1464                 if (rc) {
1465                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1466                                "file xattr region either, inode %lu\n",
1467                                 ecryptfs_inode->i_ino);
1468                         rc = -EINVAL;
1469                 }
1470                 if (crypt_stat->mount_crypt_stat->flags
1471                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1472                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1473                 } else {
1474                         printk(KERN_WARNING "Attempt to access file with "
1475                                "crypto metadata only in the extended attribute "
1476                                "region, but eCryptfs was mounted without "
1477                                "xattr support enabled. eCryptfs will not treat "
1478                                "this like an encrypted file, inode %lu\n",
1479                                 ecryptfs_inode->i_ino);
1480                         rc = -EINVAL;
1481                 }
1482         }
1483 out:
1484         if (page_virt) {
1485                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1486                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1487         }
1488         return rc;
1489 }
1490
1491 /**
1492  * ecryptfs_encrypt_filename - encrypt filename
1493  *
1494  * CBC-encrypts the filename. We do not want to encrypt the same
1495  * filename with the same key and IV, which may happen with hard
1496  * links, so we prepend random bits to each filename.
1497  *
1498  * Returns zero on success; non-zero otherwise
1499  */
1500 static int
1501 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1502                           struct ecryptfs_crypt_stat *crypt_stat,
1503                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1504 {
1505         int rc = 0;
1506
1507         filename->encrypted_filename = NULL;
1508         filename->encrypted_filename_size = 0;
1509         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1510             || (mount_crypt_stat && (mount_crypt_stat->flags
1511                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1512                 size_t packet_size;
1513                 size_t remaining_bytes;
1514
1515                 rc = ecryptfs_write_tag_70_packet(
1516                         NULL, NULL,
1517                         &filename->encrypted_filename_size,
1518                         mount_crypt_stat, NULL,
1519                         filename->filename_size);
1520                 if (rc) {
1521                         printk(KERN_ERR "%s: Error attempting to get packet "
1522                                "size for tag 72; rc = [%d]\n", __func__,
1523                                rc);
1524                         filename->encrypted_filename_size = 0;
1525                         goto out;
1526                 }
1527                 filename->encrypted_filename =
1528                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1529                 if (!filename->encrypted_filename) {
1530                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1531                                "to kmalloc [%zd] bytes\n", __func__,
1532                                filename->encrypted_filename_size);
1533                         rc = -ENOMEM;
1534                         goto out;
1535                 }
1536                 remaining_bytes = filename->encrypted_filename_size;
1537                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1538                                                   &remaining_bytes,
1539                                                   &packet_size,
1540                                                   mount_crypt_stat,
1541                                                   filename->filename,
1542                                                   filename->filename_size);
1543                 if (rc) {
1544                         printk(KERN_ERR "%s: Error attempting to generate "
1545                                "tag 70 packet; rc = [%d]\n", __func__,
1546                                rc);
1547                         kfree(filename->encrypted_filename);
1548                         filename->encrypted_filename = NULL;
1549                         filename->encrypted_filename_size = 0;
1550                         goto out;
1551                 }
1552                 filename->encrypted_filename_size = packet_size;
1553         } else {
1554                 printk(KERN_ERR "%s: No support for requested filename "
1555                        "encryption method in this release\n", __func__);
1556                 rc = -EOPNOTSUPP;
1557                 goto out;
1558         }
1559 out:
1560         return rc;
1561 }
1562
1563 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1564                                   const char *name, size_t name_size)
1565 {
1566         int rc = 0;
1567
1568         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1569         if (!(*copied_name)) {
1570                 rc = -ENOMEM;
1571                 goto out;
1572         }
1573         memcpy((void *)(*copied_name), (void *)name, name_size);
1574         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1575                                                  * in printing out the
1576                                                  * string in debug
1577                                                  * messages */
1578         (*copied_name_size) = name_size;
1579 out:
1580         return rc;
1581 }
1582
1583 /**
1584  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1585  * @key_tfm: Crypto context for key material, set by this function
1586  * @cipher_name: Name of the cipher
1587  * @key_size: Size of the key in bytes
1588  *
1589  * Returns zero on success. Any crypto_tfm structs allocated here
1590  * should be released by other functions, such as on a superblock put
1591  * event, regardless of whether this function succeeds for fails.
1592  */
1593 static int
1594 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1595                             char *cipher_name, size_t *key_size)
1596 {
1597         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1598         char *full_alg_name = NULL;
1599         int rc;
1600
1601         *key_tfm = NULL;
1602         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1603                 rc = -EINVAL;
1604                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1605                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1606                 goto out;
1607         }
1608         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1609                                                     "ecb");
1610         if (rc)
1611                 goto out;
1612         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1613         if (IS_ERR(*key_tfm)) {
1614                 rc = PTR_ERR(*key_tfm);
1615                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1616                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1617                 goto out;
1618         }
1619         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1620         if (*key_size == 0) {
1621                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1622
1623                 *key_size = alg->max_keysize;
1624         }
1625         get_random_bytes(dummy_key, *key_size);
1626         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1627         if (rc) {
1628                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1629                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1630                        rc);
1631                 rc = -EINVAL;
1632                 goto out;
1633         }
1634 out:
1635         kfree(full_alg_name);
1636         return rc;
1637 }
1638
1639 struct kmem_cache *ecryptfs_key_tfm_cache;
1640 static struct list_head key_tfm_list;
1641 struct mutex key_tfm_list_mutex;
1642
1643 int __init ecryptfs_init_crypto(void)
1644 {
1645         mutex_init(&key_tfm_list_mutex);
1646         INIT_LIST_HEAD(&key_tfm_list);
1647         return 0;
1648 }
1649
1650 /**
1651  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1652  *
1653  * Called only at module unload time
1654  */
1655 int ecryptfs_destroy_crypto(void)
1656 {
1657         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1658
1659         mutex_lock(&key_tfm_list_mutex);
1660         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1661                                  key_tfm_list) {
1662                 list_del(&key_tfm->key_tfm_list);
1663                 if (key_tfm->key_tfm)
1664                         crypto_free_blkcipher(key_tfm->key_tfm);
1665                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1666         }
1667         mutex_unlock(&key_tfm_list_mutex);
1668         return 0;
1669 }
1670
1671 int
1672 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1673                          size_t key_size)
1674 {
1675         struct ecryptfs_key_tfm *tmp_tfm;
1676         int rc = 0;
1677
1678         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1679
1680         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1681         if (key_tfm != NULL)
1682                 (*key_tfm) = tmp_tfm;
1683         if (!tmp_tfm) {
1684                 rc = -ENOMEM;
1685                 printk(KERN_ERR "Error attempting to allocate from "
1686                        "ecryptfs_key_tfm_cache\n");
1687                 goto out;
1688         }
1689         mutex_init(&tmp_tfm->key_tfm_mutex);
1690         strncpy(tmp_tfm->cipher_name, cipher_name,
1691                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1692         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1693         tmp_tfm->key_size = key_size;
1694         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1695                                          tmp_tfm->cipher_name,
1696                                          &tmp_tfm->key_size);
1697         if (rc) {
1698                 printk(KERN_ERR "Error attempting to initialize key TFM "
1699                        "cipher with name = [%s]; rc = [%d]\n",
1700                        tmp_tfm->cipher_name, rc);
1701                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1702                 if (key_tfm != NULL)
1703                         (*key_tfm) = NULL;
1704                 goto out;
1705         }
1706         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1707 out:
1708         return rc;
1709 }
1710
1711 /**
1712  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1713  * @cipher_name: the name of the cipher to search for
1714  * @key_tfm: set to corresponding tfm if found
1715  *
1716  * Searches for cached key_tfm matching @cipher_name
1717  * Must be called with &key_tfm_list_mutex held
1718  * Returns 1 if found, with @key_tfm set
1719  * Returns 0 if not found, with @key_tfm set to NULL
1720  */
1721 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1722 {
1723         struct ecryptfs_key_tfm *tmp_key_tfm;
1724
1725         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1726
1727         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1728                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1729                         if (key_tfm)
1730                                 (*key_tfm) = tmp_key_tfm;
1731                         return 1;
1732                 }
1733         }
1734         if (key_tfm)
1735                 (*key_tfm) = NULL;
1736         return 0;
1737 }
1738
1739 /**
1740  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1741  *
1742  * @tfm: set to cached tfm found, or new tfm created
1743  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1744  * @cipher_name: the name of the cipher to search for and/or add
1745  *
1746  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1747  * Searches for cached item first, and creates new if not found.
1748  * Returns 0 on success, non-zero if adding new cipher failed
1749  */
1750 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1751                                                struct mutex **tfm_mutex,
1752                                                char *cipher_name)
1753 {
1754         struct ecryptfs_key_tfm *key_tfm;
1755         int rc = 0;
1756
1757         (*tfm) = NULL;
1758         (*tfm_mutex) = NULL;
1759
1760         mutex_lock(&key_tfm_list_mutex);
1761         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1762                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1763                 if (rc) {
1764                         printk(KERN_ERR "Error adding new key_tfm to list; "
1765                                         "rc = [%d]\n", rc);
1766                         goto out;
1767                 }
1768         }
1769         (*tfm) = key_tfm->key_tfm;
1770         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1771 out:
1772         mutex_unlock(&key_tfm_list_mutex);
1773         return rc;
1774 }
1775
1776 /* 64 characters forming a 6-bit target field */
1777 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1778                                                  "EFGHIJKLMNOPQRST"
1779                                                  "UVWXYZabcdefghij"
1780                                                  "klmnopqrstuvwxyz");
1781
1782 /* We could either offset on every reverse map or just pad some 0x00's
1783  * at the front here */
1784 static const unsigned char filename_rev_map[256] = {
1785         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1786         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1787         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1788         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1789         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1790         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1791         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1792         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1793         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1794         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1795         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1796         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1797         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1798         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1799         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1800         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1801 };
1802
1803 /**
1804  * ecryptfs_encode_for_filename
1805  * @dst: Destination location for encoded filename
1806  * @dst_size: Size of the encoded filename in bytes
1807  * @src: Source location for the filename to encode
1808  * @src_size: Size of the source in bytes
1809  */
1810 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1811                                   unsigned char *src, size_t src_size)
1812 {
1813         size_t num_blocks;
1814         size_t block_num = 0;
1815         size_t dst_offset = 0;
1816         unsigned char last_block[3];
1817
1818         if (src_size == 0) {
1819                 (*dst_size) = 0;
1820                 goto out;
1821         }
1822         num_blocks = (src_size / 3);
1823         if ((src_size % 3) == 0) {
1824                 memcpy(last_block, (&src[src_size - 3]), 3);
1825         } else {
1826                 num_blocks++;
1827                 last_block[2] = 0x00;
1828                 switch (src_size % 3) {
1829                 case 1:
1830                         last_block[0] = src[src_size - 1];
1831                         last_block[1] = 0x00;
1832                         break;
1833                 case 2:
1834                         last_block[0] = src[src_size - 2];
1835                         last_block[1] = src[src_size - 1];
1836                 }
1837         }
1838         (*dst_size) = (num_blocks * 4);
1839         if (!dst)
1840                 goto out;
1841         while (block_num < num_blocks) {
1842                 unsigned char *src_block;
1843                 unsigned char dst_block[4];
1844
1845                 if (block_num == (num_blocks - 1))
1846                         src_block = last_block;
1847                 else
1848                         src_block = &src[block_num * 3];
1849                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1850                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1851                                 | ((src_block[1] >> 4) & 0x0F));
1852                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1853                                 | ((src_block[2] >> 6) & 0x03));
1854                 dst_block[3] = (src_block[2] & 0x3F);
1855                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1856                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1857                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1858                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1859                 block_num++;
1860         }
1861 out:
1862         return;
1863 }
1864
1865 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1866 {
1867         /* Not exact; conservatively long. Every block of 4
1868          * encoded characters decodes into a block of 3
1869          * decoded characters. This segment of code provides
1870          * the caller with the maximum amount of allocated
1871          * space that @dst will need to point to in a
1872          * subsequent call. */
1873         return ((encoded_size + 1) * 3) / 4;
1874 }
1875
1876 /**
1877  * ecryptfs_decode_from_filename
1878  * @dst: If NULL, this function only sets @dst_size and returns. If
1879  *       non-NULL, this function decodes the encoded octets in @src
1880  *       into the memory that @dst points to.
1881  * @dst_size: Set to the size of the decoded string.
1882  * @src: The encoded set of octets to decode.
1883  * @src_size: The size of the encoded set of octets to decode.
1884  */
1885 static void
1886 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1887                               const unsigned char *src, size_t src_size)
1888 {
1889         u8 current_bit_offset = 0;
1890         size_t src_byte_offset = 0;
1891         size_t dst_byte_offset = 0;
1892
1893         if (dst == NULL) {
1894                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1895                 goto out;
1896         }
1897         while (src_byte_offset < src_size) {
1898                 unsigned char src_byte =
1899                                 filename_rev_map[(int)src[src_byte_offset]];
1900
1901                 switch (current_bit_offset) {
1902                 case 0:
1903                         dst[dst_byte_offset] = (src_byte << 2);
1904                         current_bit_offset = 6;
1905                         break;
1906                 case 6:
1907                         dst[dst_byte_offset++] |= (src_byte >> 4);
1908                         dst[dst_byte_offset] = ((src_byte & 0xF)
1909                                                  << 4);
1910                         current_bit_offset = 4;
1911                         break;
1912                 case 4:
1913                         dst[dst_byte_offset++] |= (src_byte >> 2);
1914                         dst[dst_byte_offset] = (src_byte << 6);
1915                         current_bit_offset = 2;
1916                         break;
1917                 case 2:
1918                         dst[dst_byte_offset++] |= (src_byte);
1919                         current_bit_offset = 0;
1920                         break;
1921                 }
1922                 src_byte_offset++;
1923         }
1924         (*dst_size) = dst_byte_offset;
1925 out:
1926         return;
1927 }
1928
1929 /**
1930  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1931  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1932  * @name: The plaintext name
1933  * @length: The length of the plaintext
1934  * @encoded_name: The encypted name
1935  *
1936  * Encrypts and encodes a filename into something that constitutes a
1937  * valid filename for a filesystem, with printable characters.
1938  *
1939  * We assume that we have a properly initialized crypto context,
1940  * pointed to by crypt_stat->tfm.
1941  *
1942  * Returns zero on success; non-zero on otherwise
1943  */
1944 int ecryptfs_encrypt_and_encode_filename(
1945         char **encoded_name,
1946         size_t *encoded_name_size,
1947         struct ecryptfs_crypt_stat *crypt_stat,
1948         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1949         const char *name, size_t name_size)
1950 {
1951         size_t encoded_name_no_prefix_size;
1952         int rc = 0;
1953
1954         (*encoded_name) = NULL;
1955         (*encoded_name_size) = 0;
1956         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
1957             || (mount_crypt_stat && (mount_crypt_stat->flags
1958                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
1959                 struct ecryptfs_filename *filename;
1960
1961                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1962                 if (!filename) {
1963                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1964                                "to kzalloc [%zd] bytes\n", __func__,
1965                                sizeof(*filename));
1966                         rc = -ENOMEM;
1967                         goto out;
1968                 }
1969                 filename->filename = (char *)name;
1970                 filename->filename_size = name_size;
1971                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
1972                                                mount_crypt_stat);
1973                 if (rc) {
1974                         printk(KERN_ERR "%s: Error attempting to encrypt "
1975                                "filename; rc = [%d]\n", __func__, rc);
1976                         kfree(filename);
1977                         goto out;
1978                 }
1979                 ecryptfs_encode_for_filename(
1980                         NULL, &encoded_name_no_prefix_size,
1981                         filename->encrypted_filename,
1982                         filename->encrypted_filename_size);
1983                 if ((crypt_stat && (crypt_stat->flags
1984                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1985                     || (mount_crypt_stat
1986                         && (mount_crypt_stat->flags
1987                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
1988                         (*encoded_name_size) =
1989                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1990                                  + encoded_name_no_prefix_size);
1991                 else
1992                         (*encoded_name_size) =
1993                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1994                                  + encoded_name_no_prefix_size);
1995                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1996                 if (!(*encoded_name)) {
1997                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1998                                "to kzalloc [%zd] bytes\n", __func__,
1999                                (*encoded_name_size));
2000                         rc = -ENOMEM;
2001                         kfree(filename->encrypted_filename);
2002                         kfree(filename);
2003                         goto out;
2004                 }
2005                 if ((crypt_stat && (crypt_stat->flags
2006                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2007                     || (mount_crypt_stat
2008                         && (mount_crypt_stat->flags
2009                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2010                         memcpy((*encoded_name),
2011                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2012                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2013                         ecryptfs_encode_for_filename(
2014                             ((*encoded_name)
2015                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2016                             &encoded_name_no_prefix_size,
2017                             filename->encrypted_filename,
2018                             filename->encrypted_filename_size);
2019                         (*encoded_name_size) =
2020                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2021                                  + encoded_name_no_prefix_size);
2022                         (*encoded_name)[(*encoded_name_size)] = '\0';
2023                 } else {
2024                         rc = -EOPNOTSUPP;
2025                 }
2026                 if (rc) {
2027                         printk(KERN_ERR "%s: Error attempting to encode "
2028                                "encrypted filename; rc = [%d]\n", __func__,
2029                                rc);
2030                         kfree((*encoded_name));
2031                         (*encoded_name) = NULL;
2032                         (*encoded_name_size) = 0;
2033                 }
2034                 kfree(filename->encrypted_filename);
2035                 kfree(filename);
2036         } else {
2037                 rc = ecryptfs_copy_filename(encoded_name,
2038                                             encoded_name_size,
2039                                             name, name_size);
2040         }
2041 out:
2042         return rc;
2043 }
2044
2045 /**
2046  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2047  * @plaintext_name: The plaintext name
2048  * @plaintext_name_size: The plaintext name size
2049  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2050  * @name: The filename in cipher text
2051  * @name_size: The cipher text name size
2052  *
2053  * Decrypts and decodes the filename.
2054  *
2055  * Returns zero on error; non-zero otherwise
2056  */
2057 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2058                                          size_t *plaintext_name_size,
2059                                          struct super_block *sb,
2060                                          const char *name, size_t name_size)
2061 {
2062         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2063                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2064         char *decoded_name;
2065         size_t decoded_name_size;
2066         size_t packet_size;
2067         int rc = 0;
2068
2069         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2070             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2071             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2072             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2073                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2074                 const char *orig_name = name;
2075                 size_t orig_name_size = name_size;
2076
2077                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2078                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2079                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2080                                               name, name_size);
2081                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2082                 if (!decoded_name) {
2083                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2084                                "to kmalloc [%zd] bytes\n", __func__,
2085                                decoded_name_size);
2086                         rc = -ENOMEM;
2087                         goto out;
2088                 }
2089                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2090                                               name, name_size);
2091                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2092                                                   plaintext_name_size,
2093                                                   &packet_size,
2094                                                   mount_crypt_stat,
2095                                                   decoded_name,
2096                                                   decoded_name_size);
2097                 if (rc) {
2098                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2099                                "from filename; copying through filename "
2100                                "as-is\n", __func__);
2101                         rc = ecryptfs_copy_filename(plaintext_name,
2102                                                     plaintext_name_size,
2103                                                     orig_name, orig_name_size);
2104                         goto out_free;
2105                 }
2106         } else {
2107                 rc = ecryptfs_copy_filename(plaintext_name,
2108                                             plaintext_name_size,
2109                                             name, name_size);
2110                 goto out;
2111         }
2112 out_free:
2113         kfree(decoded_name);
2114 out:
2115         return rc;
2116 }
2117
2118 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2119
2120 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2121                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2122 {
2123         struct blkcipher_desc desc;
2124         struct mutex *tfm_mutex;
2125         size_t cipher_blocksize;
2126         int rc;
2127
2128         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2129                 (*namelen) = lower_namelen;
2130                 return 0;
2131         }
2132
2133         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2134                         mount_crypt_stat->global_default_fn_cipher_name);
2135         if (unlikely(rc)) {
2136                 (*namelen) = 0;
2137                 return rc;
2138         }
2139
2140         mutex_lock(tfm_mutex);
2141         cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2142         mutex_unlock(tfm_mutex);
2143
2144         /* Return an exact amount for the common cases */
2145         if (lower_namelen == NAME_MAX
2146             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2147                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2148                 return 0;
2149         }
2150
2151         /* Return a safe estimate for the uncommon cases */
2152         (*namelen) = lower_namelen;
2153         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2154         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2155         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2156         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2157         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2158         /* Worst case is that the filename is padded nearly a full block size */
2159         (*namelen) -= cipher_blocksize - 1;
2160
2161         if ((*namelen) < 0)
2162                 (*namelen) = 0;
2163
2164         return 0;
2165 }