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