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->global_auth_tok_key
 262                     && !(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
 263                         key_put(auth_tok->global_auth_tok_key);
 264                 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
 265         }
 266         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 267         memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
 268 }
 269
 270 /**
 271  * virt_to_scatterlist
 272  * @addr: Virtual address
 273  * @size: Size of data; should be an even multiple of the block size
 274  * @sg: Pointer to scatterlist array; set to NULL to obtain only
 275  *      the number of scatterlist structs required in array
 276  * @sg_size: Max array size
 277  *
 278  * Fills in a scatterlist array with page references for a passed
 279  * virtual address.
 280  *
 281  * Returns the number of scatterlist structs in array used
 282  */
 283 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 284                         int sg_size)
 285 {
 286         int i = 0;
 287         struct page *pg;
 288         int offset;
 289         int remainder_of_page;
 290
 291         sg_init_table(sg, sg_size);
 292
 293         while (size > 0 && i < sg_size) {
 294                 pg = virt_to_page(addr);
 295                 offset = offset_in_page(addr);
 296                 sg_set_page(&sg[i], pg, 0, offset);
 297                 remainder_of_page = PAGE_CACHE_SIZE - offset;
 298                 if (size >= remainder_of_page) {
 299                         sg[i].length = remainder_of_page;
 300                         addr += remainder_of_page;
 301                         size -= remainder_of_page;
 302                 } else {
 303                         sg[i].length = size;
 304                         addr += size;
 305                         size = 0;
 306                 }
 307                 i++;
 308         }
 309         if (size > 0)
 310                 return -ENOMEM;
 311         return i;
 312 }
 313
 314 struct extent_crypt_result {
 315         struct completion completion;
 316         int rc;
 317 };
 318
 319 static void extent_crypt_complete(struct crypto_async_request *req, int rc)
 320 {
 321         struct extent_crypt_result *ecr = req->data;
 322
 323         if (rc == -EINPROGRESS)
 324                 return;
 325
 326         ecr->rc = rc;
 327         complete(&ecr->completion);
 328 }
 329
 330 /**
 331  * crypt_scatterlist
 332  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
 333  * @dst_sg: Destination of the data after performing the crypto operation
 334  * @src_sg: Data to be encrypted or decrypted
 335  * @size: Length of data
 336  * @iv: IV to use
 337  * @op: ENCRYPT or DECRYPT to indicate the desired operation
 338  *
 339  * Returns the number of bytes encrypted or decrypted; negative value on error
 340  */
 341 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 342                              struct scatterlist *dst_sg,
 343                              struct scatterlist *src_sg, int size,
 344                              unsigned char *iv, int op)
 345 {
 346         struct ablkcipher_request *req = NULL;
 347         struct extent_crypt_result ecr;
 348         int rc = 0;
 349
 350         BUG_ON(!crypt_stat || !crypt_stat->tfm
 351                || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 352         if (unlikely(ecryptfs_verbosity > 0)) {
 353                 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 354                                 crypt_stat->key_size);
 355                 ecryptfs_dump_hex(crypt_stat->key,
 356                                   crypt_stat->key_size);
 357         }
 358
 359         init_completion(&ecr.completion);
 360
 361         mutex_lock(&crypt_stat->cs_tfm_mutex);
 362         req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
 363         if (!req) {
 364                 mutex_unlock(&crypt_stat->cs_tfm_mutex);
 365                 rc = -ENOMEM;
 366                 goto out;
 367         }
 368
 369         ablkcipher_request_set_callback(req,
 370                         CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
 371                         extent_crypt_complete, &ecr);
 372         /* Consider doing this once, when the file is opened */
 373         if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 374                 rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
 375                                               crypt_stat->key_size);
 376                 if (rc) {
 377                         ecryptfs_printk(KERN_ERR,
 378                                         "Error setting key; rc = [%d]\n",
 379                                         rc);
 380                         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 381                         rc = -EINVAL;
 382                         goto out;
 383                 }
 384                 crypt_stat->flags |= ECRYPTFS_KEY_SET;
 385         }
 386         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 387         ablkcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
 388         rc = op == ENCRYPT ? crypto_ablkcipher_encrypt(req) :
 389                              crypto_ablkcipher_decrypt(req);
 390         if (rc == -EINPROGRESS || rc == -EBUSY) {
 391                 struct extent_crypt_result *ecr = req->base.data;
 392
 393                 wait_for_completion(&ecr->completion);
 394                 rc = ecr->rc;
 395                 reinit_completion(&ecr->completion);
 396         }
 397 out:
 398         ablkcipher_request_free(req);
 399         return rc;
 400 }
 401
 402 /**
 403  * lower_offset_for_page
 404  *
 405  * Convert an eCryptfs page index into a lower byte offset
 406  */
 407 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 408                                     struct page *page)
 409 {
 410         return ecryptfs_lower_header_size(crypt_stat) +
 411                ((loff_t)page->index << PAGE_CACHE_SHIFT);
 412 }
 413
 414 /**
 415  * crypt_extent
 416  * @crypt_stat: crypt_stat containing cryptographic context for the
 417  *              encryption operation
 418  * @dst_page: The page to write the result into
 419  * @src_page: The page to read from
 420  * @extent_offset: Page extent offset for use in generating IV
 421  * @op: ENCRYPT or DECRYPT to indicate the desired operation
 422  *
 423  * Encrypts or decrypts one extent of data.
 424  *
 425  * Return zero on success; non-zero otherwise
 426  */
 427 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
 428                         struct page *dst_page,
 429                         struct page *src_page,
 430                         unsigned long extent_offset, int op)
 431 {
 432         pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
 433         loff_t extent_base;
 434         char extent_iv[ECRYPTFS_MAX_IV_BYTES];
 435         struct scatterlist src_sg, dst_sg;
 436         size_t extent_size = crypt_stat->extent_size;
 437         int rc;
 438
 439         extent_base = (((loff_t)page_index) * (PAGE_CACHE_SIZE / extent_size));
 440         rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 441                                 (extent_base + extent_offset));
 442         if (rc) {
 443                 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
 444                         "extent [0x%.16llx]; rc = [%d]\n",
 445                         (unsigned long long)(extent_base + extent_offset), rc);
 446                 goto out;
 447         }
 448
 449         sg_init_table(&src_sg, 1);
 450         sg_init_table(&dst_sg, 1);
 451
 452         sg_set_page(&src_sg, src_page, extent_size,
 453                     extent_offset * extent_size);
 454         sg_set_page(&dst_sg, dst_page, extent_size,
 455                     extent_offset * extent_size);
 456
 457         rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
 458                                extent_iv, op);
 459         if (rc < 0) {
 460                 printk(KERN_ERR "%s: Error attempting to crypt page with "
 461                        "page_index = [%ld], extent_offset = [%ld]; "
 462                        "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 463                 goto out;
 464         }
 465         rc = 0;
 466 out:
 467         return rc;
 468 }
 469
 470 /**
 471  * ecryptfs_encrypt_page
 472  * @page: Page mapped from the eCryptfs inode for the file; contains
 473  *        decrypted content that needs to be encrypted (to a temporary
 474  *        page; not in place) and written out to the lower file
 475  *
 476  * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
 477  * that eCryptfs pages may straddle the lower pages -- for instance,
 478  * if the file was created on a machine with an 8K page size
 479  * (resulting in an 8K header), and then the file is copied onto a
 480  * host with a 32K page size, then when reading page 0 of the eCryptfs
 481  * file, 24K of page 0 of the lower file will be read and decrypted,
 482  * and then 8K of page 1 of the lower file will be read and decrypted.
 483  *
 484  * Returns zero on success; negative on error
 485  */
 486 int ecryptfs_encrypt_page(struct page *page)
 487 {
 488         struct inode *ecryptfs_inode;
 489         struct ecryptfs_crypt_stat *crypt_stat;
 490         char *enc_extent_virt;
 491         struct page *enc_extent_page = NULL;
 492         loff_t extent_offset;
 493         loff_t lower_offset;
 494         int rc = 0;
 495
 496         ecryptfs_inode = page->mapping->host;
 497         crypt_stat =
 498                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 499         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 500         enc_extent_page = alloc_page(GFP_USER);
 501         if (!enc_extent_page) {
 502                 rc = -ENOMEM;
 503                 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
 504                                 "encrypted extent\n");
 505                 goto out;
 506         }
 507
 508         for (extent_offset = 0;
 509              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 510              extent_offset++) {
 511                 rc = crypt_extent(crypt_stat, enc_extent_page, page,
 512                                   extent_offset, ENCRYPT);
 513                 if (rc) {
 514                         printk(KERN_ERR "%s: Error encrypting extent; "
 515                                "rc = [%d]\n", __func__, rc);
 516                         goto out;
 517                 }
 518         }
 519
 520         lower_offset = lower_offset_for_page(crypt_stat, page);
 521         enc_extent_virt = kmap(enc_extent_page);
 522         rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 523                                   PAGE_CACHE_SIZE);
 524         kunmap(enc_extent_page);
 525         if (rc < 0) {
 526                 ecryptfs_printk(KERN_ERR,
 527                         "Error attempting to write lower page; rc = [%d]\n",
 528                         rc);
 529                 goto out;
 530         }
 531         rc = 0;
 532 out:
 533         if (enc_extent_page) {
 534                 __free_page(enc_extent_page);
 535         }
 536         return rc;
 537 }
 538
 539 /**
 540  * ecryptfs_decrypt_page
 541  * @page: Page mapped from the eCryptfs inode for the file; data read
 542  *        and decrypted from the lower file will be written into this
 543  *        page
 544  *
 545  * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
 546  * that eCryptfs pages may straddle the lower pages -- for instance,
 547  * if the file was created on a machine with an 8K page size
 548  * (resulting in an 8K header), and then the file is copied onto a
 549  * host with a 32K page size, then when reading page 0 of the eCryptfs
 550  * file, 24K of page 0 of the lower file will be read and decrypted,
 551  * and then 8K of page 1 of the lower file will be read and decrypted.
 552  *
 553  * Returns zero on success; negative on error
 554  */
 555 int ecryptfs_decrypt_page(struct page *page)
 556 {
 557         struct inode *ecryptfs_inode;
 558         struct ecryptfs_crypt_stat *crypt_stat;
 559         char *page_virt;
 560         unsigned long extent_offset;
 561         loff_t lower_offset;
 562         int rc = 0;
 563
 564         ecryptfs_inode = page->mapping->host;
 565         crypt_stat =
 566                 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 567         BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 568
 569         lower_offset = lower_offset_for_page(crypt_stat, page);
 570         page_virt = kmap(page);
 571         rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_CACHE_SIZE,
 572                                  ecryptfs_inode);
 573         kunmap(page);
 574         if (rc < 0) {
 575                 ecryptfs_printk(KERN_ERR,
 576                         "Error attempting to read lower page; rc = [%d]\n",
 577                         rc);
 578                 goto out;
 579         }
 580
 581         for (extent_offset = 0;
 582              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 583              extent_offset++) {
 584                 rc = crypt_extent(crypt_stat, page, page,
 585                                   extent_offset, DECRYPT);
 586                 if (rc) {
 587                         printk(KERN_ERR "%s: Error encrypting extent; "
 588                                "rc = [%d]\n", __func__, rc);
 589                         goto out;
 590                 }
 591         }
 592 out:
 593         return rc;
 594 }
 595
 596 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 597
 598 /**
 599  * ecryptfs_init_crypt_ctx
 600  * @crypt_stat: Uninitialized crypt stats structure
 601  *
 602  * Initialize the crypto context.
 603  *
 604  * TODO: Performance: Keep a cache of initialized cipher contexts;
 605  * only init if needed
 606  */
 607 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 608 {
 609         char *full_alg_name;
 610         int rc = -EINVAL;
 611
 612         ecryptfs_printk(KERN_DEBUG,
 613                         "Initializing cipher [%s]; strlen = [%d]; "
 614                         "key_size_bits = [%zd]\n",
 615                         crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 616                         crypt_stat->key_size << 3);
 617         mutex_lock(&crypt_stat->cs_tfm_mutex);
 618         if (crypt_stat->tfm) {
 619                 rc = 0;
 620                 goto out_unlock;
 621         }
 622         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 623                                                     crypt_stat->cipher, "cbc");
 624         if (rc)
 625                 goto out_unlock;
 626         crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
 627         if (IS_ERR(crypt_stat->tfm)) {
 628                 rc = PTR_ERR(crypt_stat->tfm);
 629                 crypt_stat->tfm = NULL;
 630                 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 631                                 "Error initializing cipher [%s]\n",
 632                                 full_alg_name);
 633                 goto out_free;
 634         }
 635         crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 636         rc = 0;
 637 out_free:
 638         kfree(full_alg_name);
 639 out_unlock:
 640         mutex_unlock(&crypt_stat->cs_tfm_mutex);
 641         return rc;
 642 }
 643
 644 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
 645 {
 646         int extent_size_tmp;
 647
 648         crypt_stat->extent_mask = 0xFFFFFFFF;
 649         crypt_stat->extent_shift = 0;
 650         if (crypt_stat->extent_size == 0)
 651                 return;
 652         extent_size_tmp = crypt_stat->extent_size;
 653         while ((extent_size_tmp & 0x01) == 0) {
 654                 extent_size_tmp >>= 1;
 655                 crypt_stat->extent_mask <<= 1;
 656                 crypt_stat->extent_shift++;
 657         }
 658 }
 659
 660 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
 661 {
 662         /* Default values; may be overwritten as we are parsing the
 663          * packets. */
 664         crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
 665         set_extent_mask_and_shift(crypt_stat);
 666         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
 667         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 668                 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 669         else {
 670                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
 671                         crypt_stat->metadata_size =
 672                                 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 673                 else
 674                         crypt_stat->metadata_size = PAGE_CACHE_SIZE;
 675         }
 676 }
 677
 678 /**
 679  * ecryptfs_compute_root_iv
 680  * @crypt_stats
 681  *
 682  * On error, sets the root IV to all 0's.
 683  */
 684 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
 685 {
 686         int rc = 0;
 687         char dst[MD5_DIGEST_SIZE];
 688
 689         BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
 690         BUG_ON(crypt_stat->iv_bytes <= 0);
 691         if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
 692                 rc = -EINVAL;
 693                 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
 694                                 "cannot generate root IV\n");
 695                 goto out;
 696         }
 697         rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
 698                                     crypt_stat->key_size);
 699         if (rc) {
 700                 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
 701                                 "MD5 while generating root IV\n");
 702                 goto out;
 703         }
 704         memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
 705 out:
 706         if (rc) {
 707                 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
 708                 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
 709         }
 710         return rc;
 711 }
 712
 713 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
 714 {
 715         get_random_bytes(crypt_stat->key, crypt_stat->key_size);
 716         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 717         ecryptfs_compute_root_iv(crypt_stat);
 718         if (unlikely(ecryptfs_verbosity > 0)) {
 719                 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
 720                 ecryptfs_dump_hex(crypt_stat->key,
 721                                   crypt_stat->key_size);
 722         }
 723 }
 724
 725 /**
 726  * ecryptfs_copy_mount_wide_flags_to_inode_flags
 727  * @crypt_stat: The inode's cryptographic context
 728  * @mount_crypt_stat: The mount point's cryptographic context
 729  *
 730  * This function propagates the mount-wide flags to individual inode
 731  * flags.
 732  */
 733 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
 734         struct ecryptfs_crypt_stat *crypt_stat,
 735         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 736 {
 737         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 738                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
 739         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 740                 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
 741         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
 742                 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
 743                 if (mount_crypt_stat->flags
 744                     & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
 745                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
 746                 else if (mount_crypt_stat->flags
 747                          & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
 748                         crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
 749         }
 750 }
 751
 752 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
 753         struct ecryptfs_crypt_stat *crypt_stat,
 754         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 755 {
 756         struct ecryptfs_global_auth_tok *global_auth_tok;
 757         int rc = 0;
 758
 759         mutex_lock(&crypt_stat->keysig_list_mutex);
 760         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 761
 762         list_for_each_entry(global_auth_tok,
 763                             &mount_crypt_stat->global_auth_tok_list,
 764                             mount_crypt_stat_list) {
 765                 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
 766                         continue;
 767                 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
 768                 if (rc) {
 769                         printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
 770                         goto out;
 771                 }
 772         }
 773
 774 out:
 775         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 776         mutex_unlock(&crypt_stat->keysig_list_mutex);
 777         return rc;
 778 }
 779
 780 /**
 781  * ecryptfs_set_default_crypt_stat_vals
 782  * @crypt_stat: The inode's cryptographic context
 783  * @mount_crypt_stat: The mount point's cryptographic context
 784  *
 785  * Default values in the event that policy does not override them.
 786  */
 787 static void ecryptfs_set_default_crypt_stat_vals(
 788         struct ecryptfs_crypt_stat *crypt_stat,
 789         struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
 790 {
 791         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 792                                                       mount_crypt_stat);
 793         ecryptfs_set_default_sizes(crypt_stat);
 794         strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
 795         crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
 796         crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
 797         crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
 798         crypt_stat->mount_crypt_stat = mount_crypt_stat;
 799 }
 800
 801 /**
 802  * ecryptfs_new_file_context
 803  * @ecryptfs_inode: The eCryptfs inode
 804  *
 805  * If the crypto context for the file has not yet been established,
 806  * this is where we do that.  Establishing a new crypto context
 807  * involves the following decisions:
 808  *  - What cipher to use?
 809  *  - What set of authentication tokens to use?
 810  * Here we just worry about getting enough information into the
 811  * authentication tokens so that we know that they are available.
 812  * We associate the available authentication tokens with the new file
 813  * via the set of signatures in the crypt_stat struct.  Later, when
 814  * the headers are actually written out, we may again defer to
 815  * userspace to perform the encryption of the session key; for the
 816  * foreseeable future, this will be the case with public key packets.
 817  *
 818  * Returns zero on success; non-zero otherwise
 819  */
 820 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
 821 {
 822         struct ecryptfs_crypt_stat *crypt_stat =
 823             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
 824         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 825             &ecryptfs_superblock_to_private(
 826                     ecryptfs_inode->i_sb)->mount_crypt_stat;
 827         int cipher_name_len;
 828         int rc = 0;
 829
 830         ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
 831         crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
 832         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
 833                                                       mount_crypt_stat);
 834         rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
 835                                                          mount_crypt_stat);
 836         if (rc) {
 837                 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
 838                        "to the inode key sigs; rc = [%d]\n", rc);
 839                 goto out;
 840         }
 841         cipher_name_len =
 842                 strlen(mount_crypt_stat->global_default_cipher_name);
 843         memcpy(crypt_stat->cipher,
 844                mount_crypt_stat->global_default_cipher_name,
 845                cipher_name_len);
 846         crypt_stat->cipher[cipher_name_len] = '\0';
 847         crypt_stat->key_size =
 848                 mount_crypt_stat->global_default_cipher_key_size;
 849         ecryptfs_generate_new_key(crypt_stat);
 850         rc = ecryptfs_init_crypt_ctx(crypt_stat);
 851         if (rc)
 852                 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
 853                                 "context for cipher [%s]: rc = [%d]\n",
 854                                 crypt_stat->cipher, rc);
 855 out:
 856         return rc;
 857 }
 858
 859 /**
 860  * ecryptfs_validate_marker - check for the ecryptfs marker
 861  * @data: The data block in which to check
 862  *
 863  * Returns zero if marker found; -EINVAL if not found
 864  */
 865 static int ecryptfs_validate_marker(char *data)
 866 {
 867         u32 m_1, m_2;
 868
 869         m_1 = get_unaligned_be32(data);
 870         m_2 = get_unaligned_be32(data + 4);
 871         if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
 872                 return 0;
 873         ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
 874                         "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
 875                         MAGIC_ECRYPTFS_MARKER);
 876         ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
 877                         "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
 878         return -EINVAL;
 879 }
 880
 881 struct ecryptfs_flag_map_elem {
 882         u32 file_flag;
 883         u32 local_flag;
 884 };
 885
 886 /* Add support for additional flags by adding elements here. */
 887 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
 888         {0x00000001, ECRYPTFS_ENABLE_HMAC},
 889         {0x00000002, ECRYPTFS_ENCRYPTED},
 890         {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
 891         {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
 892 };
 893
 894 /**
 895  * ecryptfs_process_flags
 896  * @crypt_stat: The cryptographic context
 897  * @page_virt: Source data to be parsed
 898  * @bytes_read: Updated with the number of bytes read
 899  *
 900  * Returns zero on success; non-zero if the flag set is invalid
 901  */
 902 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
 903                                   char *page_virt, int *bytes_read)
 904 {
 905         int rc = 0;
 906         int i;
 907         u32 flags;
 908
 909         flags = get_unaligned_be32(page_virt);
 910         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 911                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
 912                 if (flags & ecryptfs_flag_map[i].file_flag) {
 913                         crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
 914                 } else
 915                         crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
 916         /* Version is in top 8 bits of the 32-bit flag vector */
 917         crypt_stat->file_version = ((flags >> 24) & 0xFF);
 918         (*bytes_read) = 4;
 919         return rc;
 920 }
 921
 922 /**
 923  * write_ecryptfs_marker
 924  * @page_virt: The pointer to in a page to begin writing the marker
 925  * @written: Number of bytes written
 926  *
 927  * Marker = 0x3c81b7f5
 928  */
 929 static void write_ecryptfs_marker(char *page_virt, size_t *written)
 930 {
 931         u32 m_1, m_2;
 932
 933         get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
 934         m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
 935         put_unaligned_be32(m_1, page_virt);
 936         page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
 937         put_unaligned_be32(m_2, page_virt);
 938         (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
 939 }
 940
 941 void ecryptfs_write_crypt_stat_flags(char *page_virt,
 942                                      struct ecryptfs_crypt_stat *crypt_stat,
 943                                      size_t *written)
 944 {
 945         u32 flags = 0;
 946         int i;
 947
 948         for (i = 0; i < ((sizeof(ecryptfs_flag_map)
 949                           / sizeof(struct ecryptfs_flag_map_elem))); i++)
 950                 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
 951                         flags |= ecryptfs_flag_map[i].file_flag;
 952         /* Version is in top 8 bits of the 32-bit flag vector */
 953         flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
 954         put_unaligned_be32(flags, page_virt);
 955         (*written) = 4;
 956 }
 957
 958 struct ecryptfs_cipher_code_str_map_elem {
 959         char cipher_str[16];
 960         u8 cipher_code;
 961 };
 962
 963 /* Add support for additional ciphers by adding elements here. The
 964  * cipher_code is whatever OpenPGP applicatoins use to identify the
 965  * ciphers. List in order of probability. */
 966 static struct ecryptfs_cipher_code_str_map_elem
 967 ecryptfs_cipher_code_str_map[] = {
 968         {"aes",RFC2440_CIPHER_AES_128 },
 969         {"blowfish", RFC2440_CIPHER_BLOWFISH},
 970         {"des3_ede", RFC2440_CIPHER_DES3_EDE},
 971         {"cast5", RFC2440_CIPHER_CAST_5},
 972         {"twofish", RFC2440_CIPHER_TWOFISH},
 973         {"cast6", RFC2440_CIPHER_CAST_6},
 974         {"aes", RFC2440_CIPHER_AES_192},
 975         {"aes", RFC2440_CIPHER_AES_256}
 976 };
 977
 978 /**
 979  * ecryptfs_code_for_cipher_string
 980  * @cipher_name: The string alias for the cipher
 981  * @key_bytes: Length of key in bytes; used for AES code selection
 982  *
 983  * Returns zero on no match, or the cipher code on match
 984  */
 985 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 986 {
 987         int i;
 988         u8 code = 0;
 989         struct ecryptfs_cipher_code_str_map_elem *map =
 990                 ecryptfs_cipher_code_str_map;
 991
 992         if (strcmp(cipher_name, "aes") == 0) {
 993                 switch (key_bytes) {
 994                 case 16:
 995                         code = RFC2440_CIPHER_AES_128;
 996                         break;
 997                 case 24:
 998                         code = RFC2440_CIPHER_AES_192;
 999                         break;
1000                 case 32:
1001                         code = RFC2440_CIPHER_AES_256;
1002                 }
1003         } else {
1004                 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1005                         if (strcmp(cipher_name, map[i].cipher_str) == 0) {
1006                                 code = map[i].cipher_code;
1007                                 break;
1008                         }
1009         }
1010         return code;
1011 }
1012
1013 /**
1014  * ecryptfs_cipher_code_to_string
1015  * @str: Destination to write out the cipher name
1016  * @cipher_code: The code to convert to cipher name string
1017  *
1018  * Returns zero on success
1019  */
1020 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
1021 {
1022         int rc = 0;
1023         int i;
1024
1025         str[0] = '\0';
1026         for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1027                 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1028                         strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1029         if (str[0] == '\0') {
1030                 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1031                                 "[%d]\n", cipher_code);
1032                 rc = -EINVAL;
1033         }
1034         return rc;
1035 }
1036
1037 int ecryptfs_read_and_validate_header_region(struct inode *inode)
1038 {
1039         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1040         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1041         int rc;
1042
1043         rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
1044                                  inode);
1045         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1046                 return rc >= 0 ? -EINVAL : rc;
1047         rc = ecryptfs_validate_marker(marker);
1048         if (!rc)
1049                 ecryptfs_i_size_init(file_size, inode);
1050         return rc;
1051 }
1052
1053 void
1054 ecryptfs_write_header_metadata(char *virt,
1055                                struct ecryptfs_crypt_stat *crypt_stat,
1056                                size_t *written)
1057 {
1058         u32 header_extent_size;
1059         u16 num_header_extents_at_front;
1060
1061         header_extent_size = (u32)crypt_stat->extent_size;
1062         num_header_extents_at_front =
1063                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1064         put_unaligned_be32(header_extent_size, virt);
1065         virt += 4;
1066         put_unaligned_be16(num_header_extents_at_front, virt);
1067         (*written) = 6;
1068 }
1069
1070 struct kmem_cache *ecryptfs_header_cache;
1071
1072 /**
1073  * ecryptfs_write_headers_virt
1074  * @page_virt: The virtual address to write the headers to
1075  * @max: The size of memory allocated at page_virt
1076  * @size: Set to the number of bytes written by this function
1077  * @crypt_stat: The cryptographic context
1078  * @ecryptfs_dentry: The eCryptfs dentry
1079  *
1080  * Format version: 1
1081  *
1082  *   Header Extent:
1083  *     Octets 0-7:        Unencrypted file size (big-endian)
1084  *     Octets 8-15:       eCryptfs special marker
1085  *     Octets 16-19:      Flags
1086  *      Octet 16:         File format version number (between 0 and 255)
1087  *      Octets 17-18:     Reserved
1088  *      Octet 19:         Bit 1 (lsb): Reserved
1089  *                        Bit 2: Encrypted?
1090  *                        Bits 3-8: Reserved
1091  *     Octets 20-23:      Header extent size (big-endian)
1092  *     Octets 24-25:      Number of header extents at front of file
1093  *                        (big-endian)
1094  *     Octet  26:         Begin RFC 2440 authentication token packet set
1095  *   Data Extent 0:
1096  *     Lower data (CBC encrypted)
1097  *   Data Extent 1:
1098  *     Lower data (CBC encrypted)
1099  *   ...
1100  *
1101  * Returns zero on success
1102  */
1103 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1104                                        size_t *size,
1105                                        struct ecryptfs_crypt_stat *crypt_stat,
1106                                        struct dentry *ecryptfs_dentry)
1107 {
1108         int rc;
1109         size_t written;
1110         size_t offset;
1111
1112         offset = ECRYPTFS_FILE_SIZE_BYTES;
1113         write_ecryptfs_marker((page_virt + offset), &written);
1114         offset += written;
1115         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1116                                         &written);
1117         offset += written;
1118         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1119                                        &written);
1120         offset += written;
1121         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1122                                               ecryptfs_dentry, &written,
1123                                               max - offset);
1124         if (rc)
1125                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1126                                 "set; rc = [%d]\n", rc);
1127         if (size) {
1128                 offset += written;
1129                 *size = offset;
1130         }
1131         return rc;
1132 }
1133
1134 static int
1135 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1136                                     char *virt, size_t virt_len)
1137 {
1138         int rc;
1139
1140         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1141                                   0, virt_len);
1142         if (rc < 0)
1143                 printk(KERN_ERR "%s: Error attempting to write header "
1144                        "information to lower file; rc = [%d]\n", __func__, rc);
1145         else
1146                 rc = 0;
1147         return rc;
1148 }
1149
1150 static int
1151 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1152                                  char *page_virt, size_t size)
1153 {
1154         int rc;
1155
1156         rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1157                                size, 0);
1158         return rc;
1159 }
1160
1161 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1162                                                unsigned int order)
1163 {
1164         struct page *page;
1165
1166         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1167         if (page)
1168                 return (unsigned long) page_address(page);
1169         return 0;
1170 }
1171
1172 /**
1173  * ecryptfs_write_metadata
1174  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1175  * @ecryptfs_inode: The newly created eCryptfs inode
1176  *
1177  * Write the file headers out.  This will likely involve a userspace
1178  * callout, in which the session key is encrypted with one or more
1179  * public keys and/or the passphrase necessary to do the encryption is
1180  * retrieved via a prompt.  Exactly what happens at this point should
1181  * be policy-dependent.
1182  *
1183  * Returns zero on success; non-zero on error
1184  */
1185 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1186                             struct inode *ecryptfs_inode)
1187 {
1188         struct ecryptfs_crypt_stat *crypt_stat =
1189                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1190         unsigned int order;
1191         char *virt;
1192         size_t virt_len;
1193         size_t size = 0;
1194         int rc = 0;
1195
1196         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1197                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1198                         printk(KERN_ERR "Key is invalid; bailing out\n");
1199                         rc = -EINVAL;
1200                         goto out;
1201                 }
1202         } else {
1203                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1204                        __func__);
1205                 rc = -EINVAL;
1206                 goto out;
1207         }
1208         virt_len = crypt_stat->metadata_size;
1209         order = get_order(virt_len);
1210         /* Released in this function */
1211         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1212         if (!virt) {
1213                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1214                 rc = -ENOMEM;
1215                 goto out;
1216         }
1217         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1218         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1219                                          ecryptfs_dentry);
1220         if (unlikely(rc)) {
1221                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1222                        __func__, rc);
1223                 goto out_free;
1224         }
1225         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1226                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
1227                                                       size);
1228         else
1229                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1230                                                          virt_len);
1231         if (rc) {
1232                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1233                        "rc = [%d]\n", __func__, rc);
1234                 goto out_free;
1235         }
1236 out_free:
1237         free_pages((unsigned long)virt, order);
1238 out:
1239         return rc;
1240 }
1241
1242 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1243 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1244 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1245                                  char *virt, int *bytes_read,
1246                                  int validate_header_size)
1247 {
1248         int rc = 0;
1249         u32 header_extent_size;
1250         u16 num_header_extents_at_front;
1251
1252         header_extent_size = get_unaligned_be32(virt);
1253         virt += sizeof(__be32);
1254         num_header_extents_at_front = get_unaligned_be16(virt);
1255         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1256                                      * (size_t)header_extent_size));
1257         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1258         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1259             && (crypt_stat->metadata_size
1260                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1261                 rc = -EINVAL;
1262                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1263                        crypt_stat->metadata_size);
1264         }
1265         return rc;
1266 }
1267
1268 /**
1269  * set_default_header_data
1270  * @crypt_stat: The cryptographic context
1271  *
1272  * For version 0 file format; this function is only for backwards
1273  * compatibility for files created with the prior versions of
1274  * eCryptfs.
1275  */
1276 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1277 {
1278         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1279 }
1280
1281 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1282 {
1283         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1284         struct ecryptfs_crypt_stat *crypt_stat;
1285         u64 file_size;
1286
1287         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1288         mount_crypt_stat =
1289                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1290         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1291                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1292                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1293                         file_size += crypt_stat->metadata_size;
1294         } else
1295                 file_size = get_unaligned_be64(page_virt);
1296         i_size_write(inode, (loff_t)file_size);
1297         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1298 }
1299
1300 /**
1301  * ecryptfs_read_headers_virt
1302  * @page_virt: The virtual address into which to read the headers
1303  * @crypt_stat: The cryptographic context
1304  * @ecryptfs_dentry: The eCryptfs dentry
1305  * @validate_header_size: Whether to validate the header size while reading
1306  *
1307  * Read/parse the header data. The header format is detailed in the
1308  * comment block for the ecryptfs_write_headers_virt() function.
1309  *
1310  * Returns zero on success
1311  */
1312 static int ecryptfs_read_headers_virt(char *page_virt,
1313                                       struct ecryptfs_crypt_stat *crypt_stat,
1314                                       struct dentry *ecryptfs_dentry,
1315                                       int validate_header_size)
1316 {
1317         int rc = 0;
1318         int offset;
1319         int bytes_read;
1320
1321         ecryptfs_set_default_sizes(crypt_stat);
1322         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1323                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1324         offset = ECRYPTFS_FILE_SIZE_BYTES;
1325         rc = ecryptfs_validate_marker(page_virt + offset);
1326         if (rc)
1327                 goto out;
1328         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1329                 ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
1330         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1331         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1332                                     &bytes_read);
1333         if (rc) {
1334                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1335                 goto out;
1336         }
1337         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1338                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1339                                 "file version [%d] is supported by this "
1340                                 "version of eCryptfs\n",
1341                                 crypt_stat->file_version,
1342                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1343                 rc = -EINVAL;
1344                 goto out;
1345         }
1346         offset += bytes_read;
1347         if (crypt_stat->file_version >= 1) {
1348                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1349                                            &bytes_read, validate_header_size);
1350                 if (rc) {
1351                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1352                                         "metadata; rc = [%d]\n", rc);
1353                 }
1354                 offset += bytes_read;
1355         } else
1356                 set_default_header_data(crypt_stat);
1357         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1358                                        ecryptfs_dentry);
1359 out:
1360         return rc;
1361 }
1362
1363 /**
1364  * ecryptfs_read_xattr_region
1365  * @page_virt: The vitual address into which to read the xattr data
1366  * @ecryptfs_inode: The eCryptfs inode
1367  *
1368  * Attempts to read the crypto metadata from the extended attribute
1369  * region of the lower file.
1370  *
1371  * Returns zero on success; non-zero on error
1372  */
1373 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1374 {
1375         struct dentry *lower_dentry =
1376                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
1377         ssize_t size;
1378         int rc = 0;
1379
1380         size = ecryptfs_getxattr_lower(lower_dentry, ECRYPTFS_XATTR_NAME,
1381                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1382         if (size < 0) {
1383                 if (unlikely(ecryptfs_verbosity > 0))
1384                         printk(KERN_INFO "Error attempting to read the [%s] "
1385                                "xattr from the lower file; return value = "
1386                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1387                 rc = -EINVAL;
1388                 goto out;
1389         }
1390 out:
1391         return rc;
1392 }
1393
1394 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1395                                             struct inode *inode)
1396 {
1397         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1398         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1399         int rc;
1400
1401         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1402                                      ECRYPTFS_XATTR_NAME, file_size,
1403                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1404         if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1405                 return rc >= 0 ? -EINVAL : rc;
1406         rc = ecryptfs_validate_marker(marker);
1407         if (!rc)
1408                 ecryptfs_i_size_init(file_size, inode);
1409         return rc;
1410 }
1411
1412 /**
1413  * ecryptfs_read_metadata
1414  *
1415  * Common entry point for reading file metadata. From here, we could
1416  * retrieve the header information from the header region of the file,
1417  * the xattr region of the file, or some other repostory that is
1418  * stored separately from the file itself. The current implementation
1419  * supports retrieving the metadata information from the file contents
1420  * and from the xattr region.
1421  *
1422  * Returns zero if valid headers found and parsed; non-zero otherwise
1423  */
1424 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1425 {
1426         int rc;
1427         char *page_virt;
1428         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
1429         struct ecryptfs_crypt_stat *crypt_stat =
1430             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1431         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1432                 &ecryptfs_superblock_to_private(
1433                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1434
1435         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1436                                                       mount_crypt_stat);
1437         /* Read the first page from the underlying file */
1438         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1439         if (!page_virt) {
1440                 rc = -ENOMEM;
1441                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1442                        __func__);
1443                 goto out;
1444         }
1445         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1446                                  ecryptfs_inode);
1447         if (rc >= 0)
1448                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1449                                                 ecryptfs_dentry,
1450                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1451         if (rc) {
1452                 /* metadata is not in the file header, so try xattrs */
1453                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1454                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1455                 if (rc) {
1456                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1457                                "file header region or xattr region, inode %lu\n",
1458                                 ecryptfs_inode->i_ino);
1459                         rc = -EINVAL;
1460                         goto out;
1461                 }
1462                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1463                                                 ecryptfs_dentry,
1464                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1465                 if (rc) {
1466                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1467                                "file xattr region either, inode %lu\n",
1468                                 ecryptfs_inode->i_ino);
1469                         rc = -EINVAL;
1470                 }
1471                 if (crypt_stat->mount_crypt_stat->flags
1472                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1473                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1474                 } else {
1475                         printk(KERN_WARNING "Attempt to access file with "
1476                                "crypto metadata only in the extended attribute "
1477                                "region, but eCryptfs was mounted without "
1478                                "xattr support enabled. eCryptfs will not treat "
1479                                "this like an encrypted file, inode %lu\n",
1480                                 ecryptfs_inode->i_ino);
1481                         rc = -EINVAL;
1482                 }
1483         }
1484 out:
1485         if (page_virt) {
1486                 memset(page_virt, 0, PAGE_CACHE_SIZE);
1487                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1488         }
1489         return rc;
1490 }
1491
1492 /**
1493  * ecryptfs_encrypt_filename - encrypt filename
1494  *
1495  * CBC-encrypts the filename. We do not want to encrypt the same
1496  * filename with the same key and IV, which may happen with hard
1497  * links, so we prepend random bits to each filename.
1498  *
1499  * Returns zero on success; non-zero otherwise
1500  */
1501 static int
1502 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1503                           struct ecryptfs_crypt_stat *crypt_stat,
1504                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1505 {
1506         int rc = 0;
1507
1508         filename->encrypted_filename = NULL;
1509         filename->encrypted_filename_size = 0;
1510         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1511             || (mount_crypt_stat && (mount_crypt_stat->flags
1512                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
1513                 size_t packet_size;
1514                 size_t remaining_bytes;
1515
1516                 rc = ecryptfs_write_tag_70_packet(
1517                         NULL, NULL,
1518                         &filename->encrypted_filename_size,
1519                         mount_crypt_stat, NULL,
1520                         filename->filename_size);
1521                 if (rc) {
1522                         printk(KERN_ERR "%s: Error attempting to get packet "
1523                                "size for tag 72; rc = [%d]\n", __func__,
1524                                rc);
1525                         filename->encrypted_filename_size = 0;
1526                         goto out;
1527                 }
1528                 filename->encrypted_filename =
1529                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1530                 if (!filename->encrypted_filename) {
1531                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1532                                "to kmalloc [%zd] bytes\n", __func__,
1533                                filename->encrypted_filename_size);
1534                         rc = -ENOMEM;
1535                         goto out;
1536                 }
1537                 remaining_bytes = filename->encrypted_filename_size;
1538                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1539                                                   &remaining_bytes,
1540                                                   &packet_size,
1541                                                   mount_crypt_stat,
1542                                                   filename->filename,
1543                                                   filename->filename_size);
1544                 if (rc) {
1545                         printk(KERN_ERR "%s: Error attempting to generate "
1546                                "tag 70 packet; rc = [%d]\n", __func__,
1547                                rc);
1548                         kfree(filename->encrypted_filename);
1549                         filename->encrypted_filename = NULL;
1550                         filename->encrypted_filename_size = 0;
1551                         goto out;
1552                 }
1553                 filename->encrypted_filename_size = packet_size;
1554         } else {
1555                 printk(KERN_ERR "%s: No support for requested filename "
1556                        "encryption method in this release\n", __func__);
1557                 rc = -EOPNOTSUPP;
1558                 goto out;
1559         }
1560 out:
1561         return rc;
1562 }
1563
1564 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1565                                   const char *name, size_t name_size)
1566 {
1567         int rc = 0;
1568
1569         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1570         if (!(*copied_name)) {
1571                 rc = -ENOMEM;
1572                 goto out;
1573         }
1574         memcpy((void *)(*copied_name), (void *)name, name_size);
1575         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1576                                                  * in printing out the
1577                                                  * string in debug
1578                                                  * messages */
1579         (*copied_name_size) = name_size;
1580 out:
1581         return rc;
1582 }
1583
1584 /**
1585  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1586  * @key_tfm: Crypto context for key material, set by this function
1587  * @cipher_name: Name of the cipher
1588  * @key_size: Size of the key in bytes
1589  *
1590  * Returns zero on success. Any crypto_tfm structs allocated here
1591  * should be released by other functions, such as on a superblock put
1592  * event, regardless of whether this function succeeds for fails.
1593  */
1594 static int
1595 ecryptfs_process_key_cipher(struct crypto_blkcipher **key_tfm,
1596                             char *cipher_name, size_t *key_size)
1597 {
1598         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1599         char *full_alg_name = NULL;
1600         int rc;
1601
1602         *key_tfm = NULL;
1603         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1604                 rc = -EINVAL;
1605                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1606                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1607                 goto out;
1608         }
1609         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1610                                                     "ecb");
1611         if (rc)
1612                 goto out;
1613         *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1614         if (IS_ERR(*key_tfm)) {
1615                 rc = PTR_ERR(*key_tfm);
1616                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1617                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1618                 goto out;
1619         }
1620         crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1621         if (*key_size == 0) {
1622                 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1623
1624                 *key_size = alg->max_keysize;
1625         }
1626         get_random_bytes(dummy_key, *key_size);
1627         rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1628         if (rc) {
1629                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1630                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1631                        rc);
1632                 rc = -EINVAL;
1633                 goto out;
1634         }
1635 out:
1636         kfree(full_alg_name);
1637         return rc;
1638 }
1639
1640 struct kmem_cache *ecryptfs_key_tfm_cache;
1641 static struct list_head key_tfm_list;
1642 struct mutex key_tfm_list_mutex;
1643
1644 int __init ecryptfs_init_crypto(void)
1645 {
1646         mutex_init(&key_tfm_list_mutex);
1647         INIT_LIST_HEAD(&key_tfm_list);
1648         return 0;
1649 }
1650
1651 /**
1652  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1653  *
1654  * Called only at module unload time
1655  */
1656 int ecryptfs_destroy_crypto(void)
1657 {
1658         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1659
1660         mutex_lock(&key_tfm_list_mutex);
1661         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1662                                  key_tfm_list) {
1663                 list_del(&key_tfm->key_tfm_list);
1664                 if (key_tfm->key_tfm)
1665                         crypto_free_blkcipher(key_tfm->key_tfm);
1666                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1667         }
1668         mutex_unlock(&key_tfm_list_mutex);
1669         return 0;
1670 }
1671
1672 int
1673 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1674                          size_t key_size)
1675 {
1676         struct ecryptfs_key_tfm *tmp_tfm;
1677         int rc = 0;
1678
1679         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1680
1681         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1682         if (key_tfm != NULL)
1683                 (*key_tfm) = tmp_tfm;
1684         if (!tmp_tfm) {
1685                 rc = -ENOMEM;
1686                 printk(KERN_ERR "Error attempting to allocate from "
1687                        "ecryptfs_key_tfm_cache\n");
1688                 goto out;
1689         }
1690         mutex_init(&tmp_tfm->key_tfm_mutex);
1691         strncpy(tmp_tfm->cipher_name, cipher_name,
1692                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1693         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1694         tmp_tfm->key_size = key_size;
1695         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1696                                          tmp_tfm->cipher_name,
1697                                          &tmp_tfm->key_size);
1698         if (rc) {
1699                 printk(KERN_ERR "Error attempting to initialize key TFM "
1700                        "cipher with name = [%s]; rc = [%d]\n",
1701                        tmp_tfm->cipher_name, rc);
1702                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1703                 if (key_tfm != NULL)
1704                         (*key_tfm) = NULL;
1705                 goto out;
1706         }
1707         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1708 out:
1709         return rc;
1710 }
1711
1712 /**
1713  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1714  * @cipher_name: the name of the cipher to search for
1715  * @key_tfm: set to corresponding tfm if found
1716  *
1717  * Searches for cached key_tfm matching @cipher_name
1718  * Must be called with &key_tfm_list_mutex held
1719  * Returns 1 if found, with @key_tfm set
1720  * Returns 0 if not found, with @key_tfm set to NULL
1721  */
1722 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1723 {
1724         struct ecryptfs_key_tfm *tmp_key_tfm;
1725
1726         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1727
1728         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1729                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1730                         if (key_tfm)
1731                                 (*key_tfm) = tmp_key_tfm;
1732                         return 1;
1733                 }
1734         }
1735         if (key_tfm)
1736                 (*key_tfm) = NULL;
1737         return 0;
1738 }
1739
1740 /**
1741  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1742  *
1743  * @tfm: set to cached tfm found, or new tfm created
1744  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1745  * @cipher_name: the name of the cipher to search for and/or add
1746  *
1747  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1748  * Searches for cached item first, and creates new if not found.
1749  * Returns 0 on success, non-zero if adding new cipher failed
1750  */
1751 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_blkcipher **tfm,
1752                                                struct mutex **tfm_mutex,
1753                                                char *cipher_name)
1754 {
1755         struct ecryptfs_key_tfm *key_tfm;
1756         int rc = 0;
1757
1758         (*tfm) = NULL;
1759         (*tfm_mutex) = NULL;
1760
1761         mutex_lock(&key_tfm_list_mutex);
1762         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1763                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1764                 if (rc) {
1765                         printk(KERN_ERR "Error adding new key_tfm to list; "
1766                                         "rc = [%d]\n", rc);
1767                         goto out;
1768                 }
1769         }
1770         (*tfm) = key_tfm->key_tfm;
1771         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1772 out:
1773         mutex_unlock(&key_tfm_list_mutex);
1774         return rc;
1775 }
1776
1777 /* 64 characters forming a 6-bit target field */
1778 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1779                                                  "EFGHIJKLMNOPQRST"
1780                                                  "UVWXYZabcdefghij"
1781                                                  "klmnopqrstuvwxyz");
1782
1783 /* We could either offset on every reverse map or just pad some 0x00's
1784  * at the front here */
1785 static const unsigned char filename_rev_map[256] = {
1786         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1787         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1788         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1789         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1790         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1791         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1792         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1793         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1794         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1795         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1796         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1797         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1798         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1799         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1800         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1801         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1802 };
1803
1804 /**
1805  * ecryptfs_encode_for_filename
1806  * @dst: Destination location for encoded filename
1807  * @dst_size: Size of the encoded filename in bytes
1808  * @src: Source location for the filename to encode
1809  * @src_size: Size of the source in bytes
1810  */
1811 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1812                                   unsigned char *src, size_t src_size)
1813 {
1814         size_t num_blocks;
1815         size_t block_num = 0;
1816         size_t dst_offset = 0;
1817         unsigned char last_block[3];
1818
1819         if (src_size == 0) {
1820                 (*dst_size) = 0;
1821                 goto out;
1822         }
1823         num_blocks = (src_size / 3);
1824         if ((src_size % 3) == 0) {
1825                 memcpy(last_block, (&src[src_size - 3]), 3);
1826         } else {
1827                 num_blocks++;
1828                 last_block[2] = 0x00;
1829                 switch (src_size % 3) {
1830                 case 1:
1831                         last_block[0] = src[src_size - 1];
1832                         last_block[1] = 0x00;
1833                         break;
1834                 case 2:
1835                         last_block[0] = src[src_size - 2];
1836                         last_block[1] = src[src_size - 1];
1837                 }
1838         }
1839         (*dst_size) = (num_blocks * 4);
1840         if (!dst)
1841                 goto out;
1842         while (block_num < num_blocks) {
1843                 unsigned char *src_block;
1844                 unsigned char dst_block[4];
1845
1846                 if (block_num == (num_blocks - 1))
1847                         src_block = last_block;
1848                 else
1849                         src_block = &src[block_num * 3];
1850                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1851                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1852                                 | ((src_block[1] >> 4) & 0x0F));
1853                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1854                                 | ((src_block[2] >> 6) & 0x03));
1855                 dst_block[3] = (src_block[2] & 0x3F);
1856                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1857                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1858                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1859                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1860                 block_num++;
1861         }
1862 out:
1863         return;
1864 }
1865
1866 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1867 {
1868         /* Not exact; conservatively long. Every block of 4
1869          * encoded characters decodes into a block of 3
1870          * decoded characters. This segment of code provides
1871          * the caller with the maximum amount of allocated
1872          * space that @dst will need to point to in a
1873          * subsequent call. */
1874         return ((encoded_size + 1) * 3) / 4;
1875 }
1876
1877 /**
1878  * ecryptfs_decode_from_filename
1879  * @dst: If NULL, this function only sets @dst_size and returns. If
1880  *       non-NULL, this function decodes the encoded octets in @src
1881  *       into the memory that @dst points to.
1882  * @dst_size: Set to the size of the decoded string.
1883  * @src: The encoded set of octets to decode.
1884  * @src_size: The size of the encoded set of octets to decode.
1885  */
1886 static void
1887 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1888                               const unsigned char *src, size_t src_size)
1889 {
1890         u8 current_bit_offset = 0;
1891         size_t src_byte_offset = 0;
1892         size_t dst_byte_offset = 0;
1893
1894         if (dst == NULL) {
1895                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1896                 goto out;
1897         }
1898         while (src_byte_offset < src_size) {
1899                 unsigned char src_byte =
1900                                 filename_rev_map[(int)src[src_byte_offset]];
1901
1902                 switch (current_bit_offset) {
1903                 case 0:
1904                         dst[dst_byte_offset] = (src_byte << 2);
1905                         current_bit_offset = 6;
1906                         break;
1907                 case 6:
1908                         dst[dst_byte_offset++] |= (src_byte >> 4);
1909                         dst[dst_byte_offset] = ((src_byte & 0xF)
1910                                                  << 4);
1911                         current_bit_offset = 4;
1912                         break;
1913                 case 4:
1914                         dst[dst_byte_offset++] |= (src_byte >> 2);
1915                         dst[dst_byte_offset] = (src_byte << 6);
1916                         current_bit_offset = 2;
1917                         break;
1918                 case 2:
1919                         dst[dst_byte_offset++] |= (src_byte);
1920                         current_bit_offset = 0;
1921                         break;
1922                 }
1923                 src_byte_offset++;
1924         }
1925         (*dst_size) = dst_byte_offset;
1926 out:
1927         return;
1928 }
1929
1930 /**
1931  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1932  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1933  * @name: The plaintext name
1934  * @length: The length of the plaintext
1935  * @encoded_name: The encypted name
1936  *
1937  * Encrypts and encodes a filename into something that constitutes a
1938  * valid filename for a filesystem, with printable characters.
1939  *
1940  * We assume that we have a properly initialized crypto context,
1941  * pointed to by crypt_stat->tfm.
1942  *
1943  * Returns zero on success; non-zero on otherwise
1944  */
1945 int ecryptfs_encrypt_and_encode_filename(
1946         char **encoded_name,
1947         size_t *encoded_name_size,
1948         struct ecryptfs_crypt_stat *crypt_stat,
1949         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1950         const char *name, size_t name_size)
1951 {
1952         size_t encoded_name_no_prefix_size;
1953         int rc = 0;
1954
1955         (*encoded_name) = NULL;
1956         (*encoded_name_size) = 0;
1957         if ((crypt_stat && (crypt_stat->flags & ECRYPTFS_ENCRYPT_FILENAMES))
1958             || (mount_crypt_stat && (mount_crypt_stat->flags
1959                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES))) {
1960                 struct ecryptfs_filename *filename;
1961
1962                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1963                 if (!filename) {
1964                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1965                                "to kzalloc [%zd] bytes\n", __func__,
1966                                sizeof(*filename));
1967                         rc = -ENOMEM;
1968                         goto out;
1969                 }
1970                 filename->filename = (char *)name;
1971                 filename->filename_size = name_size;
1972                 rc = ecryptfs_encrypt_filename(filename, crypt_stat,
1973                                                mount_crypt_stat);
1974                 if (rc) {
1975                         printk(KERN_ERR "%s: Error attempting to encrypt "
1976                                "filename; rc = [%d]\n", __func__, rc);
1977                         kfree(filename);
1978                         goto out;
1979                 }
1980                 ecryptfs_encode_for_filename(
1981                         NULL, &encoded_name_no_prefix_size,
1982                         filename->encrypted_filename,
1983                         filename->encrypted_filename_size);
1984                 if ((crypt_stat && (crypt_stat->flags
1985                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
1986                     || (mount_crypt_stat
1987                         && (mount_crypt_stat->flags
1988                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)))
1989                         (*encoded_name_size) =
1990                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1991                                  + encoded_name_no_prefix_size);
1992                 else
1993                         (*encoded_name_size) =
1994                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1995                                  + encoded_name_no_prefix_size);
1996                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1997                 if (!(*encoded_name)) {
1998                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1999                                "to kzalloc [%zd] bytes\n", __func__,
2000                                (*encoded_name_size));
2001                         rc = -ENOMEM;
2002                         kfree(filename->encrypted_filename);
2003                         kfree(filename);
2004                         goto out;
2005                 }
2006                 if ((crypt_stat && (crypt_stat->flags
2007                                     & ECRYPTFS_ENCFN_USE_MOUNT_FNEK))
2008                     || (mount_crypt_stat
2009                         && (mount_crypt_stat->flags
2010                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))) {
2011                         memcpy((*encoded_name),
2012                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2013                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2014                         ecryptfs_encode_for_filename(
2015                             ((*encoded_name)
2016                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2017                             &encoded_name_no_prefix_size,
2018                             filename->encrypted_filename,
2019                             filename->encrypted_filename_size);
2020                         (*encoded_name_size) =
2021                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2022                                  + encoded_name_no_prefix_size);
2023                         (*encoded_name)[(*encoded_name_size)] = '\0';
2024                 } else {
2025                         rc = -EOPNOTSUPP;
2026                 }
2027                 if (rc) {
2028                         printk(KERN_ERR "%s: Error attempting to encode "
2029                                "encrypted filename; rc = [%d]\n", __func__,
2030                                rc);
2031                         kfree((*encoded_name));
2032                         (*encoded_name) = NULL;
2033                         (*encoded_name_size) = 0;
2034                 }
2035                 kfree(filename->encrypted_filename);
2036                 kfree(filename);
2037         } else {
2038                 rc = ecryptfs_copy_filename(encoded_name,
2039                                             encoded_name_size,
2040                                             name, name_size);
2041         }
2042 out:
2043         return rc;
2044 }
2045
2046 /**
2047  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2048  * @plaintext_name: The plaintext name
2049  * @plaintext_name_size: The plaintext name size
2050  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2051  * @name: The filename in cipher text
2052  * @name_size: The cipher text name size
2053  *
2054  * Decrypts and decodes the filename.
2055  *
2056  * Returns zero on error; non-zero otherwise
2057  */
2058 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2059                                          size_t *plaintext_name_size,
2060                                          struct super_block *sb,
2061                                          const char *name, size_t name_size)
2062 {
2063         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2064                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2065         char *decoded_name;
2066         size_t decoded_name_size;
2067         size_t packet_size;
2068         int rc = 0;
2069
2070         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2071             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2072             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2073             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2074                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2075                 const char *orig_name = name;
2076                 size_t orig_name_size = name_size;
2077
2078                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2079                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2080                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2081                                               name, name_size);
2082                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2083                 if (!decoded_name) {
2084                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2085                                "to kmalloc [%zd] bytes\n", __func__,
2086                                decoded_name_size);
2087                         rc = -ENOMEM;
2088                         goto out;
2089                 }
2090                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2091                                               name, name_size);
2092                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2093                                                   plaintext_name_size,
2094                                                   &packet_size,
2095                                                   mount_crypt_stat,
2096                                                   decoded_name,
2097                                                   decoded_name_size);
2098                 if (rc) {
2099                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2100                                "from filename; copying through filename "
2101                                "as-is\n", __func__);
2102                         rc = ecryptfs_copy_filename(plaintext_name,
2103                                                     plaintext_name_size,
2104                                                     orig_name, orig_name_size);
2105                         goto out_free;
2106                 }
2107         } else {
2108                 rc = ecryptfs_copy_filename(plaintext_name,
2109                                             plaintext_name_size,
2110                                             name, name_size);
2111                 goto out;
2112         }
2113 out_free:
2114         kfree(decoded_name);
2115 out:
2116         return rc;
2117 }
2118
2119 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2120
2121 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2122                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2123 {
2124         struct blkcipher_desc desc;
2125         struct mutex *tfm_mutex;
2126         size_t cipher_blocksize;
2127         int rc;
2128
2129         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2130                 (*namelen) = lower_namelen;
2131                 return 0;
2132         }
2133
2134         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2135                         mount_crypt_stat->global_default_fn_cipher_name);
2136         if (unlikely(rc)) {
2137                 (*namelen) = 0;
2138                 return rc;
2139         }
2140
2141         mutex_lock(tfm_mutex);
2142         cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
2143         mutex_unlock(tfm_mutex);
2144
2145         /* Return an exact amount for the common cases */
2146         if (lower_namelen == NAME_MAX
2147             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2148                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2149                 return 0;
2150         }
2151
2152         /* Return a safe estimate for the uncommon cases */
2153         (*namelen) = lower_namelen;
2154         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2155         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2156         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2157         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2158         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2159         /* Worst case is that the filename is padded nearly a full block size */
2160         (*namelen) -= cipher_blocksize - 1;
2161
2162         if ((*namelen) < 0)
2163                 (*namelen) = 0;
2164
2165         return 0;
2166 }