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 < 0)
1038                 return rc;
1039         else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1040                 return -EINVAL;
1041         rc = ecryptfs_validate_marker(marker);
1042         if (!rc)
1043                 ecryptfs_i_size_init(file_size, inode);
1044         return rc;
1045 }
1046
1047 void
1048 ecryptfs_write_header_metadata(char *virt,
1049                                struct ecryptfs_crypt_stat *crypt_stat,
1050                                size_t *written)
1051 {
1052         u32 header_extent_size;
1053         u16 num_header_extents_at_front;
1054
1055         header_extent_size = (u32)crypt_stat->extent_size;
1056         num_header_extents_at_front =
1057                 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
1058         put_unaligned_be32(header_extent_size, virt);
1059         virt += 4;
1060         put_unaligned_be16(num_header_extents_at_front, virt);
1061         (*written) = 6;
1062 }
1063
1064 struct kmem_cache *ecryptfs_header_cache;
1065
1066 /**
1067  * ecryptfs_write_headers_virt
1068  * @page_virt: The virtual address to write the headers to
1069  * @max: The size of memory allocated at page_virt
1070  * @size: Set to the number of bytes written by this function
1071  * @crypt_stat: The cryptographic context
1072  * @ecryptfs_dentry: The eCryptfs dentry
1073  *
1074  * Format version: 1
1075  *
1076  *   Header Extent:
1077  *     Octets 0-7:        Unencrypted file size (big-endian)
1078  *     Octets 8-15:       eCryptfs special marker
1079  *     Octets 16-19:      Flags
1080  *      Octet 16:         File format version number (between 0 and 255)
1081  *      Octets 17-18:     Reserved
1082  *      Octet 19:         Bit 1 (lsb): Reserved
1083  *                        Bit 2: Encrypted?
1084  *                        Bits 3-8: Reserved
1085  *     Octets 20-23:      Header extent size (big-endian)
1086  *     Octets 24-25:      Number of header extents at front of file
1087  *                        (big-endian)
1088  *     Octet  26:         Begin RFC 2440 authentication token packet set
1089  *   Data Extent 0:
1090  *     Lower data (CBC encrypted)
1091  *   Data Extent 1:
1092  *     Lower data (CBC encrypted)
1093  *   ...
1094  *
1095  * Returns zero on success
1096  */
1097 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1098                                        size_t *size,
1099                                        struct ecryptfs_crypt_stat *crypt_stat,
1100                                        struct dentry *ecryptfs_dentry)
1101 {
1102         int rc;
1103         size_t written;
1104         size_t offset;
1105
1106         offset = ECRYPTFS_FILE_SIZE_BYTES;
1107         write_ecryptfs_marker((page_virt + offset), &written);
1108         offset += written;
1109         ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1110                                         &written);
1111         offset += written;
1112         ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1113                                        &written);
1114         offset += written;
1115         rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1116                                               ecryptfs_dentry, &written,
1117                                               max - offset);
1118         if (rc)
1119                 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1120                                 "set; rc = [%d]\n", rc);
1121         if (size) {
1122                 offset += written;
1123                 *size = offset;
1124         }
1125         return rc;
1126 }
1127
1128 static int
1129 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1130                                     char *virt, size_t virt_len)
1131 {
1132         int rc;
1133
1134         rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1135                                   0, virt_len);
1136         if (rc < 0)
1137                 printk(KERN_ERR "%s: Error attempting to write header "
1138                        "information to lower file; rc = [%d]\n", __func__, rc);
1139         else
1140                 rc = 0;
1141         return rc;
1142 }
1143
1144 static int
1145 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1146                                  struct inode *ecryptfs_inode,
1147                                  char *page_virt, size_t size)
1148 {
1149         int rc;
1150
1151         rc = ecryptfs_setxattr(ecryptfs_dentry, ecryptfs_inode,
1152                                ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1153         return rc;
1154 }
1155
1156 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1157                                                unsigned int order)
1158 {
1159         struct page *page;
1160
1161         page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1162         if (page)
1163                 return (unsigned long) page_address(page);
1164         return 0;
1165 }
1166
1167 /**
1168  * ecryptfs_write_metadata
1169  * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1170  * @ecryptfs_inode: The newly created eCryptfs inode
1171  *
1172  * Write the file headers out.  This will likely involve a userspace
1173  * callout, in which the session key is encrypted with one or more
1174  * public keys and/or the passphrase necessary to do the encryption is
1175  * retrieved via a prompt.  Exactly what happens at this point should
1176  * be policy-dependent.
1177  *
1178  * Returns zero on success; non-zero on error
1179  */
1180 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1181                             struct inode *ecryptfs_inode)
1182 {
1183         struct ecryptfs_crypt_stat *crypt_stat =
1184                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1185         unsigned int order;
1186         char *virt;
1187         size_t virt_len;
1188         size_t size = 0;
1189         int rc = 0;
1190
1191         if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1192                 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1193                         printk(KERN_ERR "Key is invalid; bailing out\n");
1194                         rc = -EINVAL;
1195                         goto out;
1196                 }
1197         } else {
1198                 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1199                        __func__);
1200                 rc = -EINVAL;
1201                 goto out;
1202         }
1203         virt_len = crypt_stat->metadata_size;
1204         order = get_order(virt_len);
1205         /* Released in this function */
1206         virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1207         if (!virt) {
1208                 printk(KERN_ERR "%s: Out of memory\n", __func__);
1209                 rc = -ENOMEM;
1210                 goto out;
1211         }
1212         /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1213         rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1214                                          ecryptfs_dentry);
1215         if (unlikely(rc)) {
1216                 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1217                        __func__, rc);
1218                 goto out_free;
1219         }
1220         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1221                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1222                                                       virt, size);
1223         else
1224                 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1225                                                          virt_len);
1226         if (rc) {
1227                 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1228                        "rc = [%d]\n", __func__, rc);
1229                 goto out_free;
1230         }
1231 out_free:
1232         free_pages((unsigned long)virt, order);
1233 out:
1234         return rc;
1235 }
1236
1237 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1238 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1239 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1240                                  char *virt, int *bytes_read,
1241                                  int validate_header_size)
1242 {
1243         int rc = 0;
1244         u32 header_extent_size;
1245         u16 num_header_extents_at_front;
1246
1247         header_extent_size = get_unaligned_be32(virt);
1248         virt += sizeof(__be32);
1249         num_header_extents_at_front = get_unaligned_be16(virt);
1250         crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1251                                      * (size_t)header_extent_size));
1252         (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1253         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1254             && (crypt_stat->metadata_size
1255                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1256                 rc = -EINVAL;
1257                 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1258                        crypt_stat->metadata_size);
1259         }
1260         return rc;
1261 }
1262
1263 /**
1264  * set_default_header_data
1265  * @crypt_stat: The cryptographic context
1266  *
1267  * For version 0 file format; this function is only for backwards
1268  * compatibility for files created with the prior versions of
1269  * eCryptfs.
1270  */
1271 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1272 {
1273         crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1274 }
1275
1276 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1277 {
1278         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1279         struct ecryptfs_crypt_stat *crypt_stat;
1280         u64 file_size;
1281
1282         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1283         mount_crypt_stat =
1284                 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1285         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1286                 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1287                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1288                         file_size += crypt_stat->metadata_size;
1289         } else
1290                 file_size = get_unaligned_be64(page_virt);
1291         i_size_write(inode, (loff_t)file_size);
1292         crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1293 }
1294
1295 /**
1296  * ecryptfs_read_headers_virt
1297  * @page_virt: The virtual address into which to read the headers
1298  * @crypt_stat: The cryptographic context
1299  * @ecryptfs_dentry: The eCryptfs dentry
1300  * @validate_header_size: Whether to validate the header size while reading
1301  *
1302  * Read/parse the header data. The header format is detailed in the
1303  * comment block for the ecryptfs_write_headers_virt() function.
1304  *
1305  * Returns zero on success
1306  */
1307 static int ecryptfs_read_headers_virt(char *page_virt,
1308                                       struct ecryptfs_crypt_stat *crypt_stat,
1309                                       struct dentry *ecryptfs_dentry,
1310                                       int validate_header_size)
1311 {
1312         int rc = 0;
1313         int offset;
1314         int bytes_read;
1315
1316         ecryptfs_set_default_sizes(crypt_stat);
1317         crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1318                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1319         offset = ECRYPTFS_FILE_SIZE_BYTES;
1320         rc = ecryptfs_validate_marker(page_virt + offset);
1321         if (rc)
1322                 goto out;
1323         if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1324                 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1325         offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1326         rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1327                                     &bytes_read);
1328         if (rc) {
1329                 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1330                 goto out;
1331         }
1332         if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1333                 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1334                                 "file version [%d] is supported by this "
1335                                 "version of eCryptfs\n",
1336                                 crypt_stat->file_version,
1337                                 ECRYPTFS_SUPPORTED_FILE_VERSION);
1338                 rc = -EINVAL;
1339                 goto out;
1340         }
1341         offset += bytes_read;
1342         if (crypt_stat->file_version >= 1) {
1343                 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1344                                            &bytes_read, validate_header_size);
1345                 if (rc) {
1346                         ecryptfs_printk(KERN_WARNING, "Error reading header "
1347                                         "metadata; rc = [%d]\n", rc);
1348                 }
1349                 offset += bytes_read;
1350         } else
1351                 set_default_header_data(crypt_stat);
1352         rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1353                                        ecryptfs_dentry);
1354 out:
1355         return rc;
1356 }
1357
1358 /**
1359  * ecryptfs_read_xattr_region
1360  * @page_virt: The vitual address into which to read the xattr data
1361  * @ecryptfs_inode: The eCryptfs inode
1362  *
1363  * Attempts to read the crypto metadata from the extended attribute
1364  * region of the lower file.
1365  *
1366  * Returns zero on success; non-zero on error
1367  */
1368 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1369 {
1370         struct dentry *lower_dentry =
1371                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1372         ssize_t size;
1373         int rc = 0;
1374
1375         size = ecryptfs_getxattr_lower(lower_dentry,
1376                                        ecryptfs_inode_to_lower(ecryptfs_inode),
1377                                        ECRYPTFS_XATTR_NAME,
1378                                        page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1379         if (size < 0) {
1380                 if (unlikely(ecryptfs_verbosity > 0))
1381                         printk(KERN_INFO "Error attempting to read the [%s] "
1382                                "xattr from the lower file; return value = "
1383                                "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1384                 rc = -EINVAL;
1385                 goto out;
1386         }
1387 out:
1388         return rc;
1389 }
1390
1391 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1392                                             struct inode *inode)
1393 {
1394         u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1395         u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1396         int rc;
1397
1398         rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1399                                      ecryptfs_inode_to_lower(inode),
1400                                      ECRYPTFS_XATTR_NAME, file_size,
1401                                      ECRYPTFS_SIZE_AND_MARKER_BYTES);
1402         if (rc < 0)
1403                 return rc;
1404         else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1405                 return -EINVAL;
1406         rc = ecryptfs_validate_marker(marker);
1407         if (!rc)
1408                 ecryptfs_i_size_init(file_size, inode);
1409         return rc;
1410 }
1411
1412 /**
1413  * ecryptfs_read_metadata
1414  *
1415  * Common entry point for reading file metadata. From here, we could
1416  * retrieve the header information from the header region of the file,
1417  * the xattr region of the file, or some other repository that is
1418  * stored separately from the file itself. The current implementation
1419  * supports retrieving the metadata information from the file contents
1420  * and from the xattr region.
1421  *
1422  * Returns zero if valid headers found and parsed; non-zero otherwise
1423  */
1424 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1425 {
1426         int rc;
1427         char *page_virt;
1428         struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1429         struct ecryptfs_crypt_stat *crypt_stat =
1430             &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1431         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1432                 &ecryptfs_superblock_to_private(
1433                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
1434
1435         ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1436                                                       mount_crypt_stat);
1437         /* Read the first page from the underlying file */
1438         page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1439         if (!page_virt) {
1440                 rc = -ENOMEM;
1441                 printk(KERN_ERR "%s: Unable to allocate page_virt\n",
1442                        __func__);
1443                 goto out;
1444         }
1445         rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1446                                  ecryptfs_inode);
1447         if (rc >= 0)
1448                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1449                                                 ecryptfs_dentry,
1450                                                 ECRYPTFS_VALIDATE_HEADER_SIZE);
1451         if (rc) {
1452                 /* metadata is not in the file header, so try xattrs */
1453                 memset(page_virt, 0, PAGE_SIZE);
1454                 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1455                 if (rc) {
1456                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1457                                "file header region or xattr region, inode %lu\n",
1458                                 ecryptfs_inode->i_ino);
1459                         rc = -EINVAL;
1460                         goto out;
1461                 }
1462                 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1463                                                 ecryptfs_dentry,
1464                                                 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1465                 if (rc) {
1466                         printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1467                                "file xattr region either, inode %lu\n",
1468                                 ecryptfs_inode->i_ino);
1469                         rc = -EINVAL;
1470                 }
1471                 if (crypt_stat->mount_crypt_stat->flags
1472                     & ECRYPTFS_XATTR_METADATA_ENABLED) {
1473                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1474                 } else {
1475                         printk(KERN_WARNING "Attempt to access file with "
1476                                "crypto metadata only in the extended attribute "
1477                                "region, but eCryptfs was mounted without "
1478                                "xattr support enabled. eCryptfs will not treat "
1479                                "this like an encrypted file, inode %lu\n",
1480                                 ecryptfs_inode->i_ino);
1481                         rc = -EINVAL;
1482                 }
1483         }
1484 out:
1485         if (page_virt) {
1486                 memset(page_virt, 0, PAGE_SIZE);
1487                 kmem_cache_free(ecryptfs_header_cache, page_virt);
1488         }
1489         return rc;
1490 }
1491
1492 /**
1493  * ecryptfs_encrypt_filename - encrypt filename
1494  *
1495  * CBC-encrypts the filename. We do not want to encrypt the same
1496  * filename with the same key and IV, which may happen with hard
1497  * links, so we prepend random bits to each filename.
1498  *
1499  * Returns zero on success; non-zero otherwise
1500  */
1501 static int
1502 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1503                           struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1504 {
1505         int rc = 0;
1506
1507         filename->encrypted_filename = NULL;
1508         filename->encrypted_filename_size = 0;
1509         if (mount_crypt_stat && (mount_crypt_stat->flags
1510                                      & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1511                 size_t packet_size;
1512                 size_t remaining_bytes;
1513
1514                 rc = ecryptfs_write_tag_70_packet(
1515                         NULL, NULL,
1516                         &filename->encrypted_filename_size,
1517                         mount_crypt_stat, NULL,
1518                         filename->filename_size);
1519                 if (rc) {
1520                         printk(KERN_ERR "%s: Error attempting to get packet "
1521                                "size for tag 72; rc = [%d]\n", __func__,
1522                                rc);
1523                         filename->encrypted_filename_size = 0;
1524                         goto out;
1525                 }
1526                 filename->encrypted_filename =
1527                         kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1528                 if (!filename->encrypted_filename) {
1529                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1530                                "to kmalloc [%zd] bytes\n", __func__,
1531                                filename->encrypted_filename_size);
1532                         rc = -ENOMEM;
1533                         goto out;
1534                 }
1535                 remaining_bytes = filename->encrypted_filename_size;
1536                 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1537                                                   &remaining_bytes,
1538                                                   &packet_size,
1539                                                   mount_crypt_stat,
1540                                                   filename->filename,
1541                                                   filename->filename_size);
1542                 if (rc) {
1543                         printk(KERN_ERR "%s: Error attempting to generate "
1544                                "tag 70 packet; rc = [%d]\n", __func__,
1545                                rc);
1546                         kfree(filename->encrypted_filename);
1547                         filename->encrypted_filename = NULL;
1548                         filename->encrypted_filename_size = 0;
1549                         goto out;
1550                 }
1551                 filename->encrypted_filename_size = packet_size;
1552         } else {
1553                 printk(KERN_ERR "%s: No support for requested filename "
1554                        "encryption method in this release\n", __func__);
1555                 rc = -EOPNOTSUPP;
1556                 goto out;
1557         }
1558 out:
1559         return rc;
1560 }
1561
1562 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1563                                   const char *name, size_t name_size)
1564 {
1565         int rc = 0;
1566
1567         (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1568         if (!(*copied_name)) {
1569                 rc = -ENOMEM;
1570                 goto out;
1571         }
1572         memcpy((void *)(*copied_name), (void *)name, name_size);
1573         (*copied_name)[(name_size)] = '\0';     /* Only for convenience
1574                                                  * in printing out the
1575                                                  * string in debug
1576                                                  * messages */
1577         (*copied_name_size) = name_size;
1578 out:
1579         return rc;
1580 }
1581
1582 /**
1583  * ecryptfs_process_key_cipher - Perform key cipher initialization.
1584  * @key_tfm: Crypto context for key material, set by this function
1585  * @cipher_name: Name of the cipher
1586  * @key_size: Size of the key in bytes
1587  *
1588  * Returns zero on success. Any crypto_tfm structs allocated here
1589  * should be released by other functions, such as on a superblock put
1590  * event, regardless of whether this function succeeds for fails.
1591  */
1592 static int
1593 ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1594                             char *cipher_name, size_t *key_size)
1595 {
1596         char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1597         char *full_alg_name = NULL;
1598         int rc;
1599
1600         *key_tfm = NULL;
1601         if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1602                 rc = -EINVAL;
1603                 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1604                       "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1605                 goto out;
1606         }
1607         rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1608                                                     "ecb");
1609         if (rc)
1610                 goto out;
1611         *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1612         if (IS_ERR(*key_tfm)) {
1613                 rc = PTR_ERR(*key_tfm);
1614                 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1615                        "[%s]; rc = [%d]\n", full_alg_name, rc);
1616                 goto out;
1617         }
1618         crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1619         if (*key_size == 0)
1620                 *key_size = crypto_skcipher_default_keysize(*key_tfm);
1621         get_random_bytes(dummy_key, *key_size);
1622         rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1623         if (rc) {
1624                 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1625                        "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1626                        rc);
1627                 rc = -EINVAL;
1628                 goto out;
1629         }
1630 out:
1631         kfree(full_alg_name);
1632         return rc;
1633 }
1634
1635 struct kmem_cache *ecryptfs_key_tfm_cache;
1636 static struct list_head key_tfm_list;
1637 struct mutex key_tfm_list_mutex;
1638
1639 int __init ecryptfs_init_crypto(void)
1640 {
1641         mutex_init(&key_tfm_list_mutex);
1642         INIT_LIST_HEAD(&key_tfm_list);
1643         return 0;
1644 }
1645
1646 /**
1647  * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1648  *
1649  * Called only at module unload time
1650  */
1651 int ecryptfs_destroy_crypto(void)
1652 {
1653         struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1654
1655         mutex_lock(&key_tfm_list_mutex);
1656         list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1657                                  key_tfm_list) {
1658                 list_del(&key_tfm->key_tfm_list);
1659                 crypto_free_skcipher(key_tfm->key_tfm);
1660                 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1661         }
1662         mutex_unlock(&key_tfm_list_mutex);
1663         return 0;
1664 }
1665
1666 int
1667 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1668                          size_t key_size)
1669 {
1670         struct ecryptfs_key_tfm *tmp_tfm;
1671         int rc = 0;
1672
1673         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1674
1675         tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1676         if (key_tfm != NULL)
1677                 (*key_tfm) = tmp_tfm;
1678         if (!tmp_tfm) {
1679                 rc = -ENOMEM;
1680                 printk(KERN_ERR "Error attempting to allocate from "
1681                        "ecryptfs_key_tfm_cache\n");
1682                 goto out;
1683         }
1684         mutex_init(&tmp_tfm->key_tfm_mutex);
1685         strncpy(tmp_tfm->cipher_name, cipher_name,
1686                 ECRYPTFS_MAX_CIPHER_NAME_SIZE);
1687         tmp_tfm->cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
1688         tmp_tfm->key_size = key_size;
1689         rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1690                                          tmp_tfm->cipher_name,
1691                                          &tmp_tfm->key_size);
1692         if (rc) {
1693                 printk(KERN_ERR "Error attempting to initialize key TFM "
1694                        "cipher with name = [%s]; rc = [%d]\n",
1695                        tmp_tfm->cipher_name, rc);
1696                 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1697                 if (key_tfm != NULL)
1698                         (*key_tfm) = NULL;
1699                 goto out;
1700         }
1701         list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1702 out:
1703         return rc;
1704 }
1705
1706 /**
1707  * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1708  * @cipher_name: the name of the cipher to search for
1709  * @key_tfm: set to corresponding tfm if found
1710  *
1711  * Searches for cached key_tfm matching @cipher_name
1712  * Must be called with &key_tfm_list_mutex held
1713  * Returns 1 if found, with @key_tfm set
1714  * Returns 0 if not found, with @key_tfm set to NULL
1715  */
1716 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1717 {
1718         struct ecryptfs_key_tfm *tmp_key_tfm;
1719
1720         BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1721
1722         list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1723                 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1724                         if (key_tfm)
1725                                 (*key_tfm) = tmp_key_tfm;
1726                         return 1;
1727                 }
1728         }
1729         if (key_tfm)
1730                 (*key_tfm) = NULL;
1731         return 0;
1732 }
1733
1734 /**
1735  * ecryptfs_get_tfm_and_mutex_for_cipher_name
1736  *
1737  * @tfm: set to cached tfm found, or new tfm created
1738  * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1739  * @cipher_name: the name of the cipher to search for and/or add
1740  *
1741  * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1742  * Searches for cached item first, and creates new if not found.
1743  * Returns 0 on success, non-zero if adding new cipher failed
1744  */
1745 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1746                                                struct mutex **tfm_mutex,
1747                                                char *cipher_name)
1748 {
1749         struct ecryptfs_key_tfm *key_tfm;
1750         int rc = 0;
1751
1752         (*tfm) = NULL;
1753         (*tfm_mutex) = NULL;
1754
1755         mutex_lock(&key_tfm_list_mutex);
1756         if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1757                 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1758                 if (rc) {
1759                         printk(KERN_ERR "Error adding new key_tfm to list; "
1760                                         "rc = [%d]\n", rc);
1761                         goto out;
1762                 }
1763         }
1764         (*tfm) = key_tfm->key_tfm;
1765         (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1766 out:
1767         mutex_unlock(&key_tfm_list_mutex);
1768         return rc;
1769 }
1770
1771 /* 64 characters forming a 6-bit target field */
1772 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1773                                                  "EFGHIJKLMNOPQRST"
1774                                                  "UVWXYZabcdefghij"
1775                                                  "klmnopqrstuvwxyz");
1776
1777 /* We could either offset on every reverse map or just pad some 0x00's
1778  * at the front here */
1779 static const unsigned char filename_rev_map[256] = {
1780         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1781         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1782         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1783         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1784         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1785         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1786         0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1787         0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1788         0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1789         0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1790         0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1791         0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1792         0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1793         0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1794         0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1795         0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1796 };
1797
1798 /**
1799  * ecryptfs_encode_for_filename
1800  * @dst: Destination location for encoded filename
1801  * @dst_size: Size of the encoded filename in bytes
1802  * @src: Source location for the filename to encode
1803  * @src_size: Size of the source in bytes
1804  */
1805 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1806                                   unsigned char *src, size_t src_size)
1807 {
1808         size_t num_blocks;
1809         size_t block_num = 0;
1810         size_t dst_offset = 0;
1811         unsigned char last_block[3];
1812
1813         if (src_size == 0) {
1814                 (*dst_size) = 0;
1815                 goto out;
1816         }
1817         num_blocks = (src_size / 3);
1818         if ((src_size % 3) == 0) {
1819                 memcpy(last_block, (&src[src_size - 3]), 3);
1820         } else {
1821                 num_blocks++;
1822                 last_block[2] = 0x00;
1823                 switch (src_size % 3) {
1824                 case 1:
1825                         last_block[0] = src[src_size - 1];
1826                         last_block[1] = 0x00;
1827                         break;
1828                 case 2:
1829                         last_block[0] = src[src_size - 2];
1830                         last_block[1] = src[src_size - 1];
1831                 }
1832         }
1833         (*dst_size) = (num_blocks * 4);
1834         if (!dst)
1835                 goto out;
1836         while (block_num < num_blocks) {
1837                 unsigned char *src_block;
1838                 unsigned char dst_block[4];
1839
1840                 if (block_num == (num_blocks - 1))
1841                         src_block = last_block;
1842                 else
1843                         src_block = &src[block_num * 3];
1844                 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1845                 dst_block[1] = (((src_block[0] << 4) & 0x30)
1846                                 | ((src_block[1] >> 4) & 0x0F));
1847                 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1848                                 | ((src_block[2] >> 6) & 0x03));
1849                 dst_block[3] = (src_block[2] & 0x3F);
1850                 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1851                 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1852                 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1853                 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1854                 block_num++;
1855         }
1856 out:
1857         return;
1858 }
1859
1860 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1861 {
1862         /* Not exact; conservatively long. Every block of 4
1863          * encoded characters decodes into a block of 3
1864          * decoded characters. This segment of code provides
1865          * the caller with the maximum amount of allocated
1866          * space that @dst will need to point to in a
1867          * subsequent call. */
1868         return ((encoded_size + 1) * 3) / 4;
1869 }
1870
1871 /**
1872  * ecryptfs_decode_from_filename
1873  * @dst: If NULL, this function only sets @dst_size and returns. If
1874  *       non-NULL, this function decodes the encoded octets in @src
1875  *       into the memory that @dst points to.
1876  * @dst_size: Set to the size of the decoded string.
1877  * @src: The encoded set of octets to decode.
1878  * @src_size: The size of the encoded set of octets to decode.
1879  */
1880 static void
1881 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1882                               const unsigned char *src, size_t src_size)
1883 {
1884         u8 current_bit_offset = 0;
1885         size_t src_byte_offset = 0;
1886         size_t dst_byte_offset = 0;
1887
1888         if (dst == NULL) {
1889                 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1890                 goto out;
1891         }
1892         while (src_byte_offset < src_size) {
1893                 unsigned char src_byte =
1894                                 filename_rev_map[(int)src[src_byte_offset]];
1895
1896                 switch (current_bit_offset) {
1897                 case 0:
1898                         dst[dst_byte_offset] = (src_byte << 2);
1899                         current_bit_offset = 6;
1900                         break;
1901                 case 6:
1902                         dst[dst_byte_offset++] |= (src_byte >> 4);
1903                         dst[dst_byte_offset] = ((src_byte & 0xF)
1904                                                  << 4);
1905                         current_bit_offset = 4;
1906                         break;
1907                 case 4:
1908                         dst[dst_byte_offset++] |= (src_byte >> 2);
1909                         dst[dst_byte_offset] = (src_byte << 6);
1910                         current_bit_offset = 2;
1911                         break;
1912                 case 2:
1913                         dst[dst_byte_offset++] |= (src_byte);
1914                         current_bit_offset = 0;
1915                         break;
1916                 }
1917                 src_byte_offset++;
1918         }
1919         (*dst_size) = dst_byte_offset;
1920 out:
1921         return;
1922 }
1923
1924 /**
1925  * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1926  * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1927  * @name: The plaintext name
1928  * @length: The length of the plaintext
1929  * @encoded_name: The encypted name
1930  *
1931  * Encrypts and encodes a filename into something that constitutes a
1932  * valid filename for a filesystem, with printable characters.
1933  *
1934  * We assume that we have a properly initialized crypto context,
1935  * pointed to by crypt_stat->tfm.
1936  *
1937  * Returns zero on success; non-zero on otherwise
1938  */
1939 int ecryptfs_encrypt_and_encode_filename(
1940         char **encoded_name,
1941         size_t *encoded_name_size,
1942         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1943         const char *name, size_t name_size)
1944 {
1945         size_t encoded_name_no_prefix_size;
1946         int rc = 0;
1947
1948         (*encoded_name) = NULL;
1949         (*encoded_name_size) = 0;
1950         if (mount_crypt_stat && (mount_crypt_stat->flags
1951                                      & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1952                 struct ecryptfs_filename *filename;
1953
1954                 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1955                 if (!filename) {
1956                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1957                                "to kzalloc [%zd] bytes\n", __func__,
1958                                sizeof(*filename));
1959                         rc = -ENOMEM;
1960                         goto out;
1961                 }
1962                 filename->filename = (char *)name;
1963                 filename->filename_size = name_size;
1964                 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1965                 if (rc) {
1966                         printk(KERN_ERR "%s: Error attempting to encrypt "
1967                                "filename; rc = [%d]\n", __func__, rc);
1968                         kfree(filename);
1969                         goto out;
1970                 }
1971                 ecryptfs_encode_for_filename(
1972                         NULL, &encoded_name_no_prefix_size,
1973                         filename->encrypted_filename,
1974                         filename->encrypted_filename_size);
1975                 if (mount_crypt_stat
1976                         && (mount_crypt_stat->flags
1977                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1978                         (*encoded_name_size) =
1979                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1980                                  + encoded_name_no_prefix_size);
1981                 else
1982                         (*encoded_name_size) =
1983                                 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1984                                  + encoded_name_no_prefix_size);
1985                 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1986                 if (!(*encoded_name)) {
1987                         printk(KERN_ERR "%s: Out of memory whilst attempting "
1988                                "to kzalloc [%zd] bytes\n", __func__,
1989                                (*encoded_name_size));
1990                         rc = -ENOMEM;
1991                         kfree(filename->encrypted_filename);
1992                         kfree(filename);
1993                         goto out;
1994                 }
1995                 if (mount_crypt_stat
1996                         && (mount_crypt_stat->flags
1997                             & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1998                         memcpy((*encoded_name),
1999                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2000                                ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
2001                         ecryptfs_encode_for_filename(
2002                             ((*encoded_name)
2003                              + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
2004                             &encoded_name_no_prefix_size,
2005                             filename->encrypted_filename,
2006                             filename->encrypted_filename_size);
2007                         (*encoded_name_size) =
2008                                 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
2009                                  + encoded_name_no_prefix_size);
2010                         (*encoded_name)[(*encoded_name_size)] = '\0';
2011                 } else {
2012                         rc = -EOPNOTSUPP;
2013                 }
2014                 if (rc) {
2015                         printk(KERN_ERR "%s: Error attempting to encode "
2016                                "encrypted filename; rc = [%d]\n", __func__,
2017                                rc);
2018                         kfree((*encoded_name));
2019                         (*encoded_name) = NULL;
2020                         (*encoded_name_size) = 0;
2021                 }
2022                 kfree(filename->encrypted_filename);
2023                 kfree(filename);
2024         } else {
2025                 rc = ecryptfs_copy_filename(encoded_name,
2026                                             encoded_name_size,
2027                                             name, name_size);
2028         }
2029 out:
2030         return rc;
2031 }
2032
2033 /**
2034  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
2035  * @plaintext_name: The plaintext name
2036  * @plaintext_name_size: The plaintext name size
2037  * @ecryptfs_dir_dentry: eCryptfs directory dentry
2038  * @name: The filename in cipher text
2039  * @name_size: The cipher text name size
2040  *
2041  * Decrypts and decodes the filename.
2042  *
2043  * Returns zero on error; non-zero otherwise
2044  */
2045 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
2046                                          size_t *plaintext_name_size,
2047                                          struct super_block *sb,
2048                                          const char *name, size_t name_size)
2049 {
2050         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2051                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
2052         char *decoded_name;
2053         size_t decoded_name_size;
2054         size_t packet_size;
2055         int rc = 0;
2056
2057         if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
2058             && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
2059             && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
2060             && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
2061                         ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
2062                 const char *orig_name = name;
2063                 size_t orig_name_size = name_size;
2064
2065                 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2066                 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2067                 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
2068                                               name, name_size);
2069                 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
2070                 if (!decoded_name) {
2071                         printk(KERN_ERR "%s: Out of memory whilst attempting "
2072                                "to kmalloc [%zd] bytes\n", __func__,
2073                                decoded_name_size);
2074                         rc = -ENOMEM;
2075                         goto out;
2076                 }
2077                 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2078                                               name, name_size);
2079                 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2080                                                   plaintext_name_size,
2081                                                   &packet_size,
2082                                                   mount_crypt_stat,
2083                                                   decoded_name,
2084                                                   decoded_name_size);
2085                 if (rc) {
2086                         printk(KERN_INFO "%s: Could not parse tag 70 packet "
2087                                "from filename; copying through filename "
2088                                "as-is\n", __func__);
2089                         rc = ecryptfs_copy_filename(plaintext_name,
2090                                                     plaintext_name_size,
2091                                                     orig_name, orig_name_size);
2092                         goto out_free;
2093                 }
2094         } else {
2095                 rc = ecryptfs_copy_filename(plaintext_name,
2096                                             plaintext_name_size,
2097                                             name, name_size);
2098                 goto out;
2099         }
2100 out_free:
2101         kfree(decoded_name);
2102 out:
2103         return rc;
2104 }
2105
2106 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16   143
2107
2108 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2109                            struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2110 {
2111         struct crypto_skcipher *tfm;
2112         struct mutex *tfm_mutex;
2113         size_t cipher_blocksize;
2114         int rc;
2115
2116         if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2117                 (*namelen) = lower_namelen;
2118                 return 0;
2119         }
2120
2121         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2122                         mount_crypt_stat->global_default_fn_cipher_name);
2123         if (unlikely(rc)) {
2124                 (*namelen) = 0;
2125                 return rc;
2126         }
2127
2128         mutex_lock(tfm_mutex);
2129         cipher_blocksize = crypto_skcipher_blocksize(tfm);
2130         mutex_unlock(tfm_mutex);
2131
2132         /* Return an exact amount for the common cases */
2133         if (lower_namelen == NAME_MAX
2134             && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2135                 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2136                 return 0;
2137         }
2138
2139         /* Return a safe estimate for the uncommon cases */
2140         (*namelen) = lower_namelen;
2141         (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2142         /* Since this is the max decoded size, subtract 1 "decoded block" len */
2143         (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2144         (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2145         (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2146         /* Worst case is that the filename is padded nearly a full block size */
2147         (*namelen) -= cipher_blocksize - 1;
2148
2149         if ((*namelen) < 0)
2150                 (*namelen) = 0;
2151
2152         return 0;
2153 }