fs/ecryptfs/keystore.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  * In-kernel key management code.  Includes functions to parse and
   4  * write authentication token-related packets with the underlying
   5  * file.
   6  *
   7  * Copyright (C) 2004-2006 International Business Machines Corp.
   8  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
   9  *              Michael C. Thompson <mcthomps@us.ibm.com>
  10  *              Trevor S. Highland <trevor.highland@gmail.com>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  25  * 02111-1307, USA.
  26  */
  27
  28 #include <linux/string.h>
  29 #include <linux/syscalls.h>
  30 #include <linux/pagemap.h>
  31 #include <linux/key.h>
  32 #include <linux/random.h>
  33 #include <linux/crypto.h>
  34 #include <linux/scatterlist.h>
  35 #include <linux/slab.h>
  36 #include "ecryptfs_kernel.h"
  37
  38 /**
  39  * request_key returned an error instead of a valid key address;
  40  * determine the type of error, make appropriate log entries, and
  41  * return an error code.
  42  */
  43 static int process_request_key_err(long err_code)
  44 {
  45         int rc = 0;
  46
  47         switch (err_code) {
  48         case -ENOKEY:
  49                 ecryptfs_printk(KERN_WARNING, "No key\n");
  50                 rc = -ENOENT;
  51                 break;
  52         case -EKEYEXPIRED:
  53                 ecryptfs_printk(KERN_WARNING, "Key expired\n");
  54                 rc = -ETIME;
  55                 break;
  56         case -EKEYREVOKED:
  57                 ecryptfs_printk(KERN_WARNING, "Key revoked\n");
  58                 rc = -EINVAL;
  59                 break;
  60         default:
  61                 ecryptfs_printk(KERN_WARNING, "Unknown error code: "
  62                                 "[0x%.16lx]\n", err_code);
  63                 rc = -EINVAL;
  64         }
  65         return rc;
  66 }
  67
  68 static int process_find_global_auth_tok_for_sig_err(int err_code)
  69 {
  70         int rc = err_code;
  71
  72         switch (err_code) {
  73         case -ENOENT:
  74                 ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
  75                 break;
  76         case -EINVAL:
  77                 ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
  78                 break;
  79         default:
  80                 rc = process_request_key_err(err_code);
  81                 break;
  82         }
  83         return rc;
  84 }
  85
  86 /**
  87  * ecryptfs_parse_packet_length
  88  * @data: Pointer to memory containing length at offset
  89  * @size: This function writes the decoded size to this memory
  90  *        address; zero on error
  91  * @length_size: The number of bytes occupied by the encoded length
  92  *
  93  * Returns zero on success; non-zero on error
  94  */
  95 int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
  96                                  size_t *length_size)
  97 {
  98         int rc = 0;
  99
 100         (*length_size) = 0;
 101         (*size) = 0;
 102         if (data[0] < 192) {
 103                 /* One-byte length */
 104                 (*size) = (unsigned char)data[0];
 105                 (*length_size) = 1;
 106         } else if (data[0] < 224) {
 107                 /* Two-byte length */
 108                 (*size) = (((unsigned char)(data[0]) - 192) * 256);
 109                 (*size) += ((unsigned char)(data[1]) + 192);
 110                 (*length_size) = 2;
 111         } else if (data[0] == 255) {
 112                 /* Five-byte length; we're not supposed to see this */
 113                 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
 114                                 "supported\n");
 115                 rc = -EINVAL;
 116                 goto out;
 117         } else {
 118                 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
 119                 rc = -EINVAL;
 120                 goto out;
 121         }
 122 out:
 123         return rc;
 124 }
 125
 126 /**
 127  * ecryptfs_write_packet_length
 128  * @dest: The byte array target into which to write the length. Must
 129  *        have at least 5 bytes allocated.
 130  * @size: The length to write.
 131  * @packet_size_length: The number of bytes used to encode the packet
 132  *                      length is written to this address.
 133  *
 134  * Returns zero on success; non-zero on error.
 135  */
 136 int ecryptfs_write_packet_length(char *dest, size_t size,
 137                                  size_t *packet_size_length)
 138 {
 139         int rc = 0;
 140
 141         if (size < 192) {
 142                 dest[0] = size;
 143                 (*packet_size_length) = 1;
 144         } else if (size < 65536) {
 145                 dest[0] = (((size - 192) / 256) + 192);
 146                 dest[1] = ((size - 192) % 256);
 147                 (*packet_size_length) = 2;
 148         } else {
 149                 rc = -EINVAL;
 150                 ecryptfs_printk(KERN_WARNING,
 151                                 "Unsupported packet size: [%zd]\n", size);
 152         }
 153         return rc;
 154 }
 155
 156 static int
 157 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
 158                     char **packet, size_t *packet_len)
 159 {
 160         size_t i = 0;
 161         size_t data_len;
 162         size_t packet_size_len;
 163         char *message;
 164         int rc;
 165
 166         /*
 167          *              ***** TAG 64 Packet Format *****
 168          *    | Content Type                       | 1 byte       |
 169          *    | Key Identifier Size                | 1 or 2 bytes |
 170          *    | Key Identifier                     | arbitrary    |
 171          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 172          *    | Encrypted File Encryption Key      | arbitrary    |
 173          */
 174         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
 175                     + session_key->encrypted_key_size);
 176         *packet = kmalloc(data_len, GFP_KERNEL);
 177         message = *packet;
 178         if (!message) {
 179                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 180                 rc = -ENOMEM;
 181                 goto out;
 182         }
 183         message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
 184         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 185                                           &packet_size_len);
 186         if (rc) {
 187                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 188                                 "header; cannot generate packet length\n");
 189                 goto out;
 190         }
 191         i += packet_size_len;
 192         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 193         i += ECRYPTFS_SIG_SIZE_HEX;
 194         rc = ecryptfs_write_packet_length(&message[i],
 195                                           session_key->encrypted_key_size,
 196                                           &packet_size_len);
 197         if (rc) {
 198                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 199                                 "header; cannot generate packet length\n");
 200                 goto out;
 201         }
 202         i += packet_size_len;
 203         memcpy(&message[i], session_key->encrypted_key,
 204                session_key->encrypted_key_size);
 205         i += session_key->encrypted_key_size;
 206         *packet_len = i;
 207 out:
 208         return rc;
 209 }
 210
 211 static int
 212 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
 213                     struct ecryptfs_message *msg)
 214 {
 215         size_t i = 0;
 216         char *data;
 217         size_t data_len;
 218         size_t m_size;
 219         size_t message_len;
 220         u16 checksum = 0;
 221         u16 expected_checksum = 0;
 222         int rc;
 223
 224         /*
 225          *              ***** TAG 65 Packet Format *****
 226          *         | Content Type             | 1 byte       |
 227          *         | Status Indicator         | 1 byte       |
 228          *         | File Encryption Key Size | 1 or 2 bytes |
 229          *         | File Encryption Key      | arbitrary    |
 230          */
 231         message_len = msg->data_len;
 232         data = msg->data;
 233         if (message_len < 4) {
 234                 rc = -EIO;
 235                 goto out;
 236         }
 237         if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
 238                 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
 239                 rc = -EIO;
 240                 goto out;
 241         }
 242         if (data[i++]) {
 243                 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
 244                                 "[%d]\n", data[i-1]);
 245                 rc = -EIO;
 246                 goto out;
 247         }
 248         rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
 249         if (rc) {
 250                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 251                                 "rc = [%d]\n", rc);
 252                 goto out;
 253         }
 254         i += data_len;
 255         if (message_len < (i + m_size)) {
 256                 ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
 257                                 "is shorter than expected\n");
 258                 rc = -EIO;
 259                 goto out;
 260         }
 261         if (m_size < 3) {
 262                 ecryptfs_printk(KERN_ERR,
 263                                 "The decrypted key is not long enough to "
 264                                 "include a cipher code and checksum\n");
 265                 rc = -EIO;
 266                 goto out;
 267         }
 268         *cipher_code = data[i++];
 269         /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
 270         session_key->decrypted_key_size = m_size - 3;
 271         if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
 272                 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
 273                                 "the maximum key size [%d]\n",
 274                                 session_key->decrypted_key_size,
 275                                 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 276                 rc = -EIO;
 277                 goto out;
 278         }
 279         memcpy(session_key->decrypted_key, &data[i],
 280                session_key->decrypted_key_size);
 281         i += session_key->decrypted_key_size;
 282         expected_checksum += (unsigned char)(data[i++]) << 8;
 283         expected_checksum += (unsigned char)(data[i++]);
 284         for (i = 0; i < session_key->decrypted_key_size; i++)
 285                 checksum += session_key->decrypted_key[i];
 286         if (expected_checksum != checksum) {
 287                 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
 288                                 "encryption  key; expected [%x]; calculated "
 289                                 "[%x]\n", expected_checksum, checksum);
 290                 rc = -EIO;
 291         }
 292 out:
 293         return rc;
 294 }
 295
 296
 297 static int
 298 write_tag_66_packet(char *signature, u8 cipher_code,
 299                     struct ecryptfs_crypt_stat *crypt_stat, char **packet,
 300                     size_t *packet_len)
 301 {
 302         size_t i = 0;
 303         size_t j;
 304         size_t data_len;
 305         size_t checksum = 0;
 306         size_t packet_size_len;
 307         char *message;
 308         int rc;
 309
 310         /*
 311          *              ***** TAG 66 Packet Format *****
 312          *         | Content Type             | 1 byte       |
 313          *         | Key Identifier Size      | 1 or 2 bytes |
 314          *         | Key Identifier           | arbitrary    |
 315          *         | File Encryption Key Size | 1 or 2 bytes |
 316          *         | File Encryption Key      | arbitrary    |
 317          */
 318         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
 319         *packet = kmalloc(data_len, GFP_KERNEL);
 320         message = *packet;
 321         if (!message) {
 322                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 323                 rc = -ENOMEM;
 324                 goto out;
 325         }
 326         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
 327         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 328                                           &packet_size_len);
 329         if (rc) {
 330                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 331                                 "header; cannot generate packet length\n");
 332                 goto out;
 333         }
 334         i += packet_size_len;
 335         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 336         i += ECRYPTFS_SIG_SIZE_HEX;
 337         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
 338         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
 339                                           &packet_size_len);
 340         if (rc) {
 341                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 342                                 "header; cannot generate packet length\n");
 343                 goto out;
 344         }
 345         i += packet_size_len;
 346         message[i++] = cipher_code;
 347         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
 348         i += crypt_stat->key_size;
 349         for (j = 0; j < crypt_stat->key_size; j++)
 350                 checksum += crypt_stat->key[j];
 351         message[i++] = (checksum / 256) % 256;
 352         message[i++] = (checksum % 256);
 353         *packet_len = i;
 354 out:
 355         return rc;
 356 }
 357
 358 static int
 359 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
 360                     struct ecryptfs_message *msg)
 361 {
 362         size_t i = 0;
 363         char *data;
 364         size_t data_len;
 365         size_t message_len;
 366         int rc;
 367
 368         /*
 369          *              ***** TAG 65 Packet Format *****
 370          *    | Content Type                       | 1 byte       |
 371          *    | Status Indicator                   | 1 byte       |
 372          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 373          *    | Encrypted File Encryption Key      | arbitrary    |
 374          */
 375         message_len = msg->data_len;
 376         data = msg->data;
 377         /* verify that everything through the encrypted FEK size is present */
 378         if (message_len < 4) {
 379                 rc = -EIO;
 380                 printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
 381                        "message length is [%d]\n", __func__, message_len, 4);
 382                 goto out;
 383         }
 384         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
 385                 rc = -EIO;
 386                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
 387                        __func__);
 388                 goto out;
 389         }
 390         if (data[i++]) {
 391                 rc = -EIO;
 392                 printk(KERN_ERR "%s: Status indicator has non zero "
 393                        "value [%d]\n", __func__, data[i-1]);
 394
 395                 goto out;
 396         }
 397         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
 398                                           &data_len);
 399         if (rc) {
 400                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 401                                 "rc = [%d]\n", rc);
 402                 goto out;
 403         }
 404         i += data_len;
 405         if (message_len < (i + key_rec->enc_key_size)) {
 406                 rc = -EIO;
 407                 printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
 408                        __func__, message_len, (i + key_rec->enc_key_size));
 409                 goto out;
 410         }
 411         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
 412                 rc = -EIO;
 413                 printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
 414                        "the maximum key size [%d]\n", __func__,
 415                        key_rec->enc_key_size,
 416                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 417                 goto out;
 418         }
 419         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
 420 out:
 421         return rc;
 422 }
 423
 424 /**
 425  * ecryptfs_verify_version
 426  * @version: The version number to confirm
 427  *
 428  * Returns zero on good version; non-zero otherwise
 429  */
 430 static int ecryptfs_verify_version(u16 version)
 431 {
 432         int rc = 0;
 433         unsigned char major;
 434         unsigned char minor;
 435
 436         major = ((version >> 8) & 0xFF);
 437         minor = (version & 0xFF);
 438         if (major != ECRYPTFS_VERSION_MAJOR) {
 439                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
 440                                 "Expected [%d]; got [%d]\n",
 441                                 ECRYPTFS_VERSION_MAJOR, major);
 442                 rc = -EINVAL;
 443                 goto out;
 444         }
 445         if (minor != ECRYPTFS_VERSION_MINOR) {
 446                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
 447                                 "Expected [%d]; got [%d]\n",
 448                                 ECRYPTFS_VERSION_MINOR, minor);
 449                 rc = -EINVAL;
 450                 goto out;
 451         }
 452 out:
 453         return rc;
 454 }
 455
 456 /**
 457  * ecryptfs_verify_auth_tok_from_key
 458  * @auth_tok_key: key containing the authentication token
 459  * @auth_tok: authentication token
 460  *
 461  * Returns zero on valid auth tok; -EINVAL otherwise
 462  */
 463 static int
 464 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
 465                                   struct ecryptfs_auth_tok **auth_tok)
 466 {
 467         int rc = 0;
 468
 469         (*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
 470         if (ecryptfs_verify_version((*auth_tok)->version)) {
 471                 printk(KERN_ERR "Data structure version mismatch. Userspace "
 472                        "tools must match eCryptfs kernel module with major "
 473                        "version [%d] and minor version [%d]\n",
 474                        ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
 475                 rc = -EINVAL;
 476                 goto out;
 477         }
 478         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
 479             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
 480                 printk(KERN_ERR "Invalid auth_tok structure "
 481                        "returned from key query\n");
 482                 rc = -EINVAL;
 483                 goto out;
 484         }
 485 out:
 486         return rc;
 487 }
 488
 489 static int
 490 ecryptfs_find_global_auth_tok_for_sig(
 491         struct key **auth_tok_key,
 492         struct ecryptfs_auth_tok **auth_tok,
 493         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
 494 {
 495         struct ecryptfs_global_auth_tok *walker;
 496         int rc = 0;
 497
 498         (*auth_tok_key) = NULL;
 499         (*auth_tok) = NULL;
 500         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 501         list_for_each_entry(walker,
 502                             &mount_crypt_stat->global_auth_tok_list,
 503                             mount_crypt_stat_list) {
 504                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
 505                         continue;
 506
 507                 if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
 508                         rc = -EINVAL;
 509                         goto out;
 510                 }
 511
 512                 rc = key_validate(walker->global_auth_tok_key);
 513                 if (rc) {
 514                         if (rc == -EKEYEXPIRED)
 515                                 goto out;
 516                         goto out_invalid_auth_tok;
 517                 }
 518
 519                 rc = ecryptfs_verify_auth_tok_from_key(
 520                                 walker->global_auth_tok_key, auth_tok);
 521                 if (rc)
 522                         goto out_invalid_auth_tok;
 523
 524                 (*auth_tok_key) = walker->global_auth_tok_key;
 525                 key_get(*auth_tok_key);
 526                 goto out;
 527         }
 528         rc = -ENOENT;
 529         goto out;
 530 out_invalid_auth_tok:
 531         printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
 532         walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
 533         key_put(walker->global_auth_tok_key);
 534         walker->global_auth_tok_key = NULL;
 535 out:
 536         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 537         return rc;
 538 }
 539
 540 /**
 541  * ecryptfs_find_auth_tok_for_sig
 542  * @auth_tok: Set to the matching auth_tok; NULL if not found
 543  * @crypt_stat: inode crypt_stat crypto context
 544  * @sig: Sig of auth_tok to find
 545  *
 546  * For now, this function simply looks at the registered auth_tok's
 547  * linked off the mount_crypt_stat, so all the auth_toks that can be
 548  * used must be registered at mount time. This function could
 549  * potentially try a lot harder to find auth_tok's (e.g., by calling
 550  * out to ecryptfsd to dynamically retrieve an auth_tok object) so
 551  * that static registration of auth_tok's will no longer be necessary.
 552  *
 553  * Returns zero on no error; non-zero on error
 554  */
 555 static int
 556 ecryptfs_find_auth_tok_for_sig(
 557         struct key **auth_tok_key,
 558         struct ecryptfs_auth_tok **auth_tok,
 559         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 560         char *sig)
 561 {
 562         int rc = 0;
 563
 564         rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
 565                                                    mount_crypt_stat, sig);
 566         if (rc == -ENOENT) {
 567                 /* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
 568                  * mount_crypt_stat structure, we prevent to use auth toks that
 569                  * are not inserted through the ecryptfs_add_global_auth_tok
 570                  * function.
 571                  */
 572                 if (mount_crypt_stat->flags
 573                                 & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 574                         return -EINVAL;
 575
 576                 rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
 577                                                        sig);
 578         }
 579         return rc;
 580 }
 581
 582 /**
 583  * write_tag_70_packet can gobble a lot of stack space. We stuff most
 584  * of the function's parameters in a kmalloc'd struct to help reduce
 585  * eCryptfs' overall stack usage.
 586  */
 587 struct ecryptfs_write_tag_70_packet_silly_stack {
 588         u8 cipher_code;
 589         size_t max_packet_size;
 590         size_t packet_size_len;
 591         size_t block_aligned_filename_size;
 592         size_t block_size;
 593         size_t i;
 594         size_t j;
 595         size_t num_rand_bytes;
 596         struct mutex *tfm_mutex;
 597         char *block_aligned_filename;
 598         struct ecryptfs_auth_tok *auth_tok;
 599         struct scatterlist src_sg;
 600         struct scatterlist dst_sg;
 601         struct blkcipher_desc desc;
 602         char iv[ECRYPTFS_MAX_IV_BYTES];
 603         char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 604         char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 605         struct hash_desc hash_desc;
 606         struct scatterlist hash_sg;
 607 };
 608
 609 /**
 610  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
 611  * @filename: NULL-terminated filename string
 612  *
 613  * This is the simplest mechanism for achieving filename encryption in
 614  * eCryptfs. It encrypts the given filename with the mount-wide
 615  * filename encryption key (FNEK) and stores it in a packet to @dest,
 616  * which the callee will encode and write directly into the dentry
 617  * name.
 618  */
 619 int
 620 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 621                              size_t *packet_size,
 622                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 623                              char *filename, size_t filename_size)
 624 {
 625         struct ecryptfs_write_tag_70_packet_silly_stack *s;
 626         struct key *auth_tok_key = NULL;
 627         int rc = 0;
 628
 629         s = kmalloc(sizeof(*s), GFP_KERNEL);
 630         if (!s) {
 631                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 632                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
 633                 rc = -ENOMEM;
 634                 goto out;
 635         }
 636         s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 637         (*packet_size) = 0;
 638         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
 639                 &s->desc.tfm,
 640                 &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
 641         if (unlikely(rc)) {
 642                 printk(KERN_ERR "Internal error whilst attempting to get "
 643                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 644                        mount_crypt_stat->global_default_fn_cipher_name, rc);
 645                 goto out;
 646         }
 647         mutex_lock(s->tfm_mutex);
 648         s->block_size = crypto_blkcipher_blocksize(s->desc.tfm);
 649         /* Plus one for the \0 separator between the random prefix
 650          * and the plaintext filename */
 651         s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
 652         s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
 653         if ((s->block_aligned_filename_size % s->block_size) != 0) {
 654                 s->num_rand_bytes += (s->block_size
 655                                       - (s->block_aligned_filename_size
 656                                          % s->block_size));
 657                 s->block_aligned_filename_size = (s->num_rand_bytes
 658                                                   + filename_size);
 659         }
 660         /* Octet 0: Tag 70 identifier
 661          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 662          *              and block-aligned encrypted filename size)
 663          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 664          * Octet N2-N3: Cipher identifier (1 octet)
 665          * Octets N3-N4: Block-aligned encrypted filename
 666          *  - Consists of a minimum number of random characters, a \0
 667          *    separator, and then the filename */
 668         s->max_packet_size = (1                   /* Tag 70 identifier */
 669                               + 3                 /* Max Tag 70 packet size */
 670                               + ECRYPTFS_SIG_SIZE /* FNEK sig */
 671                               + 1                 /* Cipher identifier */
 672                               + s->block_aligned_filename_size);
 673         if (dest == NULL) {
 674                 (*packet_size) = s->max_packet_size;
 675                 goto out_unlock;
 676         }
 677         if (s->max_packet_size > (*remaining_bytes)) {
 678                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
 679                        "[%zd] available\n", __func__, s->max_packet_size,
 680                        (*remaining_bytes));
 681                 rc = -EINVAL;
 682                 goto out_unlock;
 683         }
 684         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
 685                                             GFP_KERNEL);
 686         if (!s->block_aligned_filename) {
 687                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
 688                        "kzalloc [%zd] bytes\n", __func__,
 689                        s->block_aligned_filename_size);
 690                 rc = -ENOMEM;
 691                 goto out_unlock;
 692         }
 693         s->i = 0;
 694         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
 695         rc = ecryptfs_write_packet_length(&dest[s->i],
 696                                           (ECRYPTFS_SIG_SIZE
 697                                            + 1 /* Cipher code */
 698                                            + s->block_aligned_filename_size),
 699                                           &s->packet_size_len);
 700         if (rc) {
 701                 printk(KERN_ERR "%s: Error generating tag 70 packet "
 702                        "header; cannot generate packet length; rc = [%d]\n",
 703                        __func__, rc);
 704                 goto out_free_unlock;
 705         }
 706         s->i += s->packet_size_len;
 707         ecryptfs_from_hex(&dest[s->i],
 708                           mount_crypt_stat->global_default_fnek_sig,
 709                           ECRYPTFS_SIG_SIZE);
 710         s->i += ECRYPTFS_SIG_SIZE;
 711         s->cipher_code = ecryptfs_code_for_cipher_string(
 712                 mount_crypt_stat->global_default_fn_cipher_name,
 713                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 714         if (s->cipher_code == 0) {
 715                 printk(KERN_WARNING "%s: Unable to generate code for "
 716                        "cipher [%s] with key bytes [%zd]\n", __func__,
 717                        mount_crypt_stat->global_default_fn_cipher_name,
 718                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 719                 rc = -EINVAL;
 720                 goto out_free_unlock;
 721         }
 722         dest[s->i++] = s->cipher_code;
 723         rc = ecryptfs_find_auth_tok_for_sig(
 724                 &auth_tok_key,
 725                 &s->auth_tok, mount_crypt_stat,
 726                 mount_crypt_stat->global_default_fnek_sig);
 727         if (rc) {
 728                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 729                        "fnek sig [%s]; rc = [%d]\n", __func__,
 730                        mount_crypt_stat->global_default_fnek_sig, rc);
 731                 goto out_free_unlock;
 732         }
 733         /* TODO: Support other key modules than passphrase for
 734          * filename encryption */
 735         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
 736                 rc = -EOPNOTSUPP;
 737                 printk(KERN_INFO "%s: Filename encryption only supports "
 738                        "password tokens\n", __func__);
 739                 goto out_free_unlock;
 740         }
 741         sg_init_one(
 742                 &s->hash_sg,
 743                 (u8 *)s->auth_tok->token.password.session_key_encryption_key,
 744                 s->auth_tok->token.password.session_key_encryption_key_bytes);
 745         s->hash_desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 746         s->hash_desc.tfm = crypto_alloc_hash(ECRYPTFS_TAG_70_DIGEST, 0,
 747                                              CRYPTO_ALG_ASYNC);
 748         if (IS_ERR(s->hash_desc.tfm)) {
 749                         rc = PTR_ERR(s->hash_desc.tfm);
 750                         printk(KERN_ERR "%s: Error attempting to "
 751                                "allocate hash crypto context; rc = [%d]\n",
 752                                __func__, rc);
 753                         goto out_free_unlock;
 754         }
 755         rc = crypto_hash_init(&s->hash_desc);
 756         if (rc) {
 757                 printk(KERN_ERR
 758                        "%s: Error initializing crypto hash; rc = [%d]\n",
 759                        __func__, rc);
 760                 goto out_release_free_unlock;
 761         }
 762         rc = crypto_hash_update(
 763                 &s->hash_desc, &s->hash_sg,
 764                 s->auth_tok->token.password.session_key_encryption_key_bytes);
 765         if (rc) {
 766                 printk(KERN_ERR
 767                        "%s: Error updating crypto hash; rc = [%d]\n",
 768                        __func__, rc);
 769                 goto out_release_free_unlock;
 770         }
 771         rc = crypto_hash_final(&s->hash_desc, s->hash);
 772         if (rc) {
 773                 printk(KERN_ERR
 774                        "%s: Error finalizing crypto hash; rc = [%d]\n",
 775                        __func__, rc);
 776                 goto out_release_free_unlock;
 777         }
 778         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
 779                 s->block_aligned_filename[s->j] =
 780                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
 781                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
 782                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
 783                         sg_init_one(&s->hash_sg, (u8 *)s->hash,
 784                                     ECRYPTFS_TAG_70_DIGEST_SIZE);
 785                         rc = crypto_hash_init(&s->hash_desc);
 786                         if (rc) {
 787                                 printk(KERN_ERR
 788                                        "%s: Error initializing crypto hash; "
 789                                        "rc = [%d]\n", __func__, rc);
 790                                 goto out_release_free_unlock;
 791                         }
 792                         rc = crypto_hash_update(&s->hash_desc, &s->hash_sg,
 793                                                 ECRYPTFS_TAG_70_DIGEST_SIZE);
 794                         if (rc) {
 795                                 printk(KERN_ERR
 796                                        "%s: Error updating crypto hash; "
 797                                        "rc = [%d]\n", __func__, rc);
 798                                 goto out_release_free_unlock;
 799                         }
 800                         rc = crypto_hash_final(&s->hash_desc, s->tmp_hash);
 801                         if (rc) {
 802                                 printk(KERN_ERR
 803                                        "%s: Error finalizing crypto hash; "
 804                                        "rc = [%d]\n", __func__, rc);
 805                                 goto out_release_free_unlock;
 806                         }
 807                         memcpy(s->hash, s->tmp_hash,
 808                                ECRYPTFS_TAG_70_DIGEST_SIZE);
 809                 }
 810                 if (s->block_aligned_filename[s->j] == '\0')
 811                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
 812         }
 813         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 814                filename_size);
 815         rc = virt_to_scatterlist(s->block_aligned_filename,
 816                                  s->block_aligned_filename_size, &s->src_sg, 1);
 817         if (rc != 1) {
 818                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 819                        "convert filename memory to scatterlist; "
 820                        "expected rc = 1; got rc = [%d]. "
 821                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 822                        s->block_aligned_filename_size);
 823                 goto out_release_free_unlock;
 824         }
 825         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
 826                                  &s->dst_sg, 1);
 827         if (rc != 1) {
 828                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 829                        "convert encrypted filename memory to scatterlist; "
 830                        "expected rc = 1; got rc = [%d]. "
 831                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 832                        s->block_aligned_filename_size);
 833                 goto out_release_free_unlock;
 834         }
 835         /* The characters in the first block effectively do the job
 836          * of the IV here, so we just use 0's for the IV. Note the
 837          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
 838          * >= ECRYPTFS_MAX_IV_BYTES. */
 839         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
 840         s->desc.info = s->iv;
 841         rc = crypto_blkcipher_setkey(
 842                 s->desc.tfm,
 843                 s->auth_tok->token.password.session_key_encryption_key,
 844                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 845         if (rc < 0) {
 846                 printk(KERN_ERR "%s: Error setting key for crypto context; "
 847                        "rc = [%d]. s->auth_tok->token.password.session_key_"
 848                        "encryption_key = [0x%p]; mount_crypt_stat->"
 849                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
 850                        rc,
 851                        s->auth_tok->token.password.session_key_encryption_key,
 852                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 853                 goto out_release_free_unlock;
 854         }
 855         rc = crypto_blkcipher_encrypt_iv(&s->desc, &s->dst_sg, &s->src_sg,
 856                                          s->block_aligned_filename_size);
 857         if (rc) {
 858                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
 859                        "rc = [%d]\n", __func__, rc);
 860                 goto out_release_free_unlock;
 861         }
 862         s->i += s->block_aligned_filename_size;
 863         (*packet_size) = s->i;
 864         (*remaining_bytes) -= (*packet_size);
 865 out_release_free_unlock:
 866         crypto_free_hash(s->hash_desc.tfm);
 867 out_free_unlock:
 868         kzfree(s->block_aligned_filename);
 869 out_unlock:
 870         mutex_unlock(s->tfm_mutex);
 871 out:
 872         if (auth_tok_key)
 873                 key_put(auth_tok_key);
 874         kfree(s);
 875         return rc;
 876 }
 877
 878 struct ecryptfs_parse_tag_70_packet_silly_stack {
 879         u8 cipher_code;
 880         size_t max_packet_size;
 881         size_t packet_size_len;
 882         size_t parsed_tag_70_packet_size;
 883         size_t block_aligned_filename_size;
 884         size_t block_size;
 885         size_t i;
 886         struct mutex *tfm_mutex;
 887         char *decrypted_filename;
 888         struct ecryptfs_auth_tok *auth_tok;
 889         struct scatterlist src_sg;
 890         struct scatterlist dst_sg;
 891         struct blkcipher_desc desc;
 892         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 893         char iv[ECRYPTFS_MAX_IV_BYTES];
 894         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
 895 };
 896
 897 /**
 898  * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 899  * @filename: This function kmalloc's the memory for the filename
 900  * @filename_size: This function sets this to the amount of memory
 901  *                 kmalloc'd for the filename
 902  * @packet_size: This function sets this to the the number of octets
 903  *               in the packet parsed
 904  * @mount_crypt_stat: The mount-wide cryptographic context
 905  * @data: The memory location containing the start of the tag 70
 906  *        packet
 907  * @max_packet_size: The maximum legal size of the packet to be parsed
 908  *                   from @data
 909  *
 910  * Returns zero on success; non-zero otherwise
 911  */
 912 int
 913 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 914                              size_t *packet_size,
 915                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 916                              char *data, size_t max_packet_size)
 917 {
 918         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
 919         struct key *auth_tok_key = NULL;
 920         int rc = 0;
 921
 922         (*packet_size) = 0;
 923         (*filename_size) = 0;
 924         (*filename) = NULL;
 925         s = kmalloc(sizeof(*s), GFP_KERNEL);
 926         if (!s) {
 927                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 928                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
 929                 rc = -ENOMEM;
 930                 goto out;
 931         }
 932         s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 933         if (max_packet_size < (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1)) {
 934                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
 935                        "at least [%d]\n", __func__, max_packet_size,
 936                         (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1));
 937                 rc = -EINVAL;
 938                 goto out;
 939         }
 940         /* Octet 0: Tag 70 identifier
 941          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 942          *              and block-aligned encrypted filename size)
 943          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 944          * Octet N2-N3: Cipher identifier (1 octet)
 945          * Octets N3-N4: Block-aligned encrypted filename
 946          *  - Consists of a minimum number of random numbers, a \0
 947          *    separator, and then the filename */
 948         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
 949                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
 950                        "tag [0x%.2x]\n", __func__,
 951                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
 952                 rc = -EINVAL;
 953                 goto out;
 954         }
 955         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
 956                                           &s->parsed_tag_70_packet_size,
 957                                           &s->packet_size_len);
 958         if (rc) {
 959                 printk(KERN_WARNING "%s: Error parsing packet length; "
 960                        "rc = [%d]\n", __func__, rc);
 961                 goto out;
 962         }
 963         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
 964                                           - ECRYPTFS_SIG_SIZE - 1);
 965         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
 966             > max_packet_size) {
 967                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
 968                        "size is [%zd]\n", __func__, max_packet_size,
 969                        (1 + s->packet_size_len + 1
 970                         + s->block_aligned_filename_size));
 971                 rc = -EINVAL;
 972                 goto out;
 973         }
 974         (*packet_size) += s->packet_size_len;
 975         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
 976                         ECRYPTFS_SIG_SIZE);
 977         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 978         (*packet_size) += ECRYPTFS_SIG_SIZE;
 979         s->cipher_code = data[(*packet_size)++];
 980         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
 981         if (rc) {
 982                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
 983                        __func__, s->cipher_code);
 984                 goto out;
 985         }
 986         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->desc.tfm,
 987                                                         &s->tfm_mutex,
 988                                                         s->cipher_string);
 989         if (unlikely(rc)) {
 990                 printk(KERN_ERR "Internal error whilst attempting to get "
 991                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 992                        s->cipher_string, rc);
 993                 goto out;
 994         }
 995         mutex_lock(s->tfm_mutex);
 996         rc = virt_to_scatterlist(&data[(*packet_size)],
 997                                  s->block_aligned_filename_size, &s->src_sg, 1);
 998         if (rc != 1) {
 999                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1000                        "convert encrypted filename memory to scatterlist; "
1001                        "expected rc = 1; got rc = [%d]. "
1002                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
1003                        s->block_aligned_filename_size);
1004                 goto out_unlock;
1005         }
1006         (*packet_size) += s->block_aligned_filename_size;
1007         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
1008                                         GFP_KERNEL);
1009         if (!s->decrypted_filename) {
1010                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1011                        "kmalloc [%zd] bytes\n", __func__,
1012                        s->block_aligned_filename_size);
1013                 rc = -ENOMEM;
1014                 goto out_unlock;
1015         }
1016         rc = virt_to_scatterlist(s->decrypted_filename,
1017                                  s->block_aligned_filename_size, &s->dst_sg, 1);
1018         if (rc != 1) {
1019                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1020                        "convert decrypted filename memory to scatterlist; "
1021                        "expected rc = 1; got rc = [%d]. "
1022                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
1023                        s->block_aligned_filename_size);
1024                 goto out_free_unlock;
1025         }
1026         /* The characters in the first block effectively do the job of
1027          * the IV here, so we just use 0's for the IV. Note the
1028          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1029          * >= ECRYPTFS_MAX_IV_BYTES. */
1030         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
1031         s->desc.info = s->iv;
1032         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1033                                             &s->auth_tok, mount_crypt_stat,
1034                                             s->fnek_sig_hex);
1035         if (rc) {
1036                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
1037                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
1038                        rc);
1039                 goto out_free_unlock;
1040         }
1041         /* TODO: Support other key modules than passphrase for
1042          * filename encryption */
1043         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1044                 rc = -EOPNOTSUPP;
1045                 printk(KERN_INFO "%s: Filename encryption only supports "
1046                        "password tokens\n", __func__);
1047                 goto out_free_unlock;
1048         }
1049         rc = crypto_blkcipher_setkey(
1050                 s->desc.tfm,
1051                 s->auth_tok->token.password.session_key_encryption_key,
1052                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1053         if (rc < 0) {
1054                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1055                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1056                        "encryption_key = [0x%p]; mount_crypt_stat->"
1057                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1058                        rc,
1059                        s->auth_tok->token.password.session_key_encryption_key,
1060                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1061                 goto out_free_unlock;
1062         }
1063         rc = crypto_blkcipher_decrypt_iv(&s->desc, &s->dst_sg, &s->src_sg,
1064                                          s->block_aligned_filename_size);
1065         if (rc) {
1066                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1067                        "rc = [%d]\n", __func__, rc);
1068                 goto out_free_unlock;
1069         }
1070         s->i = 0;
1071         while (s->decrypted_filename[s->i] != '\0'
1072                && s->i < s->block_aligned_filename_size)
1073                 s->i++;
1074         if (s->i == s->block_aligned_filename_size) {
1075                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1076                        "find valid separator between random characters and "
1077                        "the filename\n", __func__);
1078                 rc = -EINVAL;
1079                 goto out_free_unlock;
1080         }
1081         s->i++;
1082         (*filename_size) = (s->block_aligned_filename_size - s->i);
1083         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1084                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1085                        "invalid\n", __func__, (*filename_size));
1086                 rc = -EINVAL;
1087                 goto out_free_unlock;
1088         }
1089         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1090         if (!(*filename)) {
1091                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1092                        "kmalloc [%zd] bytes\n", __func__,
1093                        ((*filename_size) + 1));
1094                 rc = -ENOMEM;
1095                 goto out_free_unlock;
1096         }
1097         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1098         (*filename)[(*filename_size)] = '\0';
1099 out_free_unlock:
1100         kfree(s->decrypted_filename);
1101 out_unlock:
1102         mutex_unlock(s->tfm_mutex);
1103 out:
1104         if (rc) {
1105                 (*packet_size) = 0;
1106                 (*filename_size) = 0;
1107                 (*filename) = NULL;
1108         }
1109         if (auth_tok_key)
1110                 key_put(auth_tok_key);
1111         kfree(s);
1112         return rc;
1113 }
1114
1115 static int
1116 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1117 {
1118         int rc = 0;
1119
1120         (*sig) = NULL;
1121         switch (auth_tok->token_type) {
1122         case ECRYPTFS_PASSWORD:
1123                 (*sig) = auth_tok->token.password.signature;
1124                 break;
1125         case ECRYPTFS_PRIVATE_KEY:
1126                 (*sig) = auth_tok->token.private_key.signature;
1127                 break;
1128         default:
1129                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1130                        auth_tok->token_type);
1131                 rc = -EINVAL;
1132         }
1133         return rc;
1134 }
1135
1136 /**
1137  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1138  * @auth_tok: The key authentication token used to decrypt the session key
1139  * @crypt_stat: The cryptographic context
1140  *
1141  * Returns zero on success; non-zero error otherwise.
1142  */
1143 static int
1144 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1145                                   struct ecryptfs_crypt_stat *crypt_stat)
1146 {
1147         u8 cipher_code = 0;
1148         struct ecryptfs_msg_ctx *msg_ctx;
1149         struct ecryptfs_message *msg = NULL;
1150         char *auth_tok_sig;
1151         char *payload;
1152         size_t payload_len;
1153         int rc;
1154
1155         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1156         if (rc) {
1157                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1158                        auth_tok->token_type);
1159                 goto out;
1160         }
1161         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1162                                  &payload, &payload_len);
1163         if (rc) {
1164                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1165                 goto out;
1166         }
1167         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1168         if (rc) {
1169                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1170                                 "ecryptfsd\n");
1171                 goto out;
1172         }
1173         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1174         if (rc) {
1175                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1176                                 "from the user space daemon\n");
1177                 rc = -EIO;
1178                 goto out;
1179         }
1180         rc = parse_tag_65_packet(&(auth_tok->session_key),
1181                                  &cipher_code, msg);
1182         if (rc) {
1183                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1184                        rc);
1185                 goto out;
1186         }
1187         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1188         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1189                auth_tok->session_key.decrypted_key_size);
1190         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1191         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1192         if (rc) {
1193                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1194                                 cipher_code)
1195                 goto out;
1196         }
1197         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1198         if (ecryptfs_verbosity > 0) {
1199                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1200                 ecryptfs_dump_hex(crypt_stat->key,
1201                                   crypt_stat->key_size);
1202         }
1203 out:
1204         if (msg)
1205                 kfree(msg);
1206         return rc;
1207 }
1208
1209 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1210 {
1211         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1212         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1213
1214         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1215                                  auth_tok_list_head, list) {
1216                 list_del(&auth_tok_list_item->list);
1217                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1218                                 auth_tok_list_item);
1219         }
1220 }
1221
1222 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1223
1224 /**
1225  * parse_tag_1_packet
1226  * @crypt_stat: The cryptographic context to modify based on packet contents
1227  * @data: The raw bytes of the packet.
1228  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1229  *                 a new authentication token will be placed at the
1230  *                 end of this list for this packet.
1231  * @new_auth_tok: Pointer to a pointer to memory that this function
1232  *                allocates; sets the memory address of the pointer to
1233  *                NULL on error. This object is added to the
1234  *                auth_tok_list.
1235  * @packet_size: This function writes the size of the parsed packet
1236  *               into this memory location; zero on error.
1237  * @max_packet_size: The maximum allowable packet size
1238  *
1239  * Returns zero on success; non-zero on error.
1240  */
1241 static int
1242 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1243                    unsigned char *data, struct list_head *auth_tok_list,
1244                    struct ecryptfs_auth_tok **new_auth_tok,
1245                    size_t *packet_size, size_t max_packet_size)
1246 {
1247         size_t body_size;
1248         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1249         size_t length_size;
1250         int rc = 0;
1251
1252         (*packet_size) = 0;
1253         (*new_auth_tok) = NULL;
1254         /**
1255          * This format is inspired by OpenPGP; see RFC 2440
1256          * packet tag 1
1257          *
1258          * Tag 1 identifier (1 byte)
1259          * Max Tag 1 packet size (max 3 bytes)
1260          * Version (1 byte)
1261          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1262          * Cipher identifier (1 byte)
1263          * Encrypted key size (arbitrary)
1264          *
1265          * 12 bytes minimum packet size
1266          */
1267         if (unlikely(max_packet_size < 12)) {
1268                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1269                 rc = -EINVAL;
1270                 goto out;
1271         }
1272         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1273                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1274                        ECRYPTFS_TAG_1_PACKET_TYPE);
1275                 rc = -EINVAL;
1276                 goto out;
1277         }
1278         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1279          * at end of function upon failure */
1280         auth_tok_list_item =
1281                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1282                                   GFP_KERNEL);
1283         if (!auth_tok_list_item) {
1284                 printk(KERN_ERR "Unable to allocate memory\n");
1285                 rc = -ENOMEM;
1286                 goto out;
1287         }
1288         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1289         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1290                                           &length_size);
1291         if (rc) {
1292                 printk(KERN_WARNING "Error parsing packet length; "
1293                        "rc = [%d]\n", rc);
1294                 goto out_free;
1295         }
1296         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1297                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1298                 rc = -EINVAL;
1299                 goto out_free;
1300         }
1301         (*packet_size) += length_size;
1302         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1303                 printk(KERN_WARNING "Packet size exceeds max\n");
1304                 rc = -EINVAL;
1305                 goto out_free;
1306         }
1307         if (unlikely(data[(*packet_size)++] != 0x03)) {
1308                 printk(KERN_WARNING "Unknown version number [%d]\n",
1309                        data[(*packet_size) - 1]);
1310                 rc = -EINVAL;
1311                 goto out_free;
1312         }
1313         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1314                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1315         *packet_size += ECRYPTFS_SIG_SIZE;
1316         /* This byte is skipped because the kernel does not need to
1317          * know which public key encryption algorithm was used */
1318         (*packet_size)++;
1319         (*new_auth_tok)->session_key.encrypted_key_size =
1320                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1321         if ((*new_auth_tok)->session_key.encrypted_key_size
1322             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1323                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1324                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
1325                 rc = -EINVAL;
1326                 goto out;
1327         }
1328         memcpy((*new_auth_tok)->session_key.encrypted_key,
1329                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1330         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1331         (*new_auth_tok)->session_key.flags &=
1332                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1333         (*new_auth_tok)->session_key.flags |=
1334                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1335         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1336         (*new_auth_tok)->flags = 0;
1337         (*new_auth_tok)->session_key.flags &=
1338                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1339         (*new_auth_tok)->session_key.flags &=
1340                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1341         list_add(&auth_tok_list_item->list, auth_tok_list);
1342         goto out;
1343 out_free:
1344         (*new_auth_tok) = NULL;
1345         memset(auth_tok_list_item, 0,
1346                sizeof(struct ecryptfs_auth_tok_list_item));
1347         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1348                         auth_tok_list_item);
1349 out:
1350         if (rc)
1351                 (*packet_size) = 0;
1352         return rc;
1353 }
1354
1355 /**
1356  * parse_tag_3_packet
1357  * @crypt_stat: The cryptographic context to modify based on packet
1358  *              contents.
1359  * @data: The raw bytes of the packet.
1360  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1361  *                 a new authentication token will be placed at the end
1362  *                 of this list for this packet.
1363  * @new_auth_tok: Pointer to a pointer to memory that this function
1364  *                allocates; sets the memory address of the pointer to
1365  *                NULL on error. This object is added to the
1366  *                auth_tok_list.
1367  * @packet_size: This function writes the size of the parsed packet
1368  *               into this memory location; zero on error.
1369  * @max_packet_size: maximum number of bytes to parse
1370  *
1371  * Returns zero on success; non-zero on error.
1372  */
1373 static int
1374 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1375                    unsigned char *data, struct list_head *auth_tok_list,
1376                    struct ecryptfs_auth_tok **new_auth_tok,
1377                    size_t *packet_size, size_t max_packet_size)
1378 {
1379         size_t body_size;
1380         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1381         size_t length_size;
1382         int rc = 0;
1383
1384         (*packet_size) = 0;
1385         (*new_auth_tok) = NULL;
1386         /**
1387          *This format is inspired by OpenPGP; see RFC 2440
1388          * packet tag 3
1389          *
1390          * Tag 3 identifier (1 byte)
1391          * Max Tag 3 packet size (max 3 bytes)
1392          * Version (1 byte)
1393          * Cipher code (1 byte)
1394          * S2K specifier (1 byte)
1395          * Hash identifier (1 byte)
1396          * Salt (ECRYPTFS_SALT_SIZE)
1397          * Hash iterations (1 byte)
1398          * Encrypted key (arbitrary)
1399          *
1400          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1401          */
1402         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1403                 printk(KERN_ERR "Max packet size too large\n");
1404                 rc = -EINVAL;
1405                 goto out;
1406         }
1407         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1408                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1409                        ECRYPTFS_TAG_3_PACKET_TYPE);
1410                 rc = -EINVAL;
1411                 goto out;
1412         }
1413         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1414          * at end of function upon failure */
1415         auth_tok_list_item =
1416             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1417         if (!auth_tok_list_item) {
1418                 printk(KERN_ERR "Unable to allocate memory\n");
1419                 rc = -ENOMEM;
1420                 goto out;
1421         }
1422         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1423         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1424                                           &length_size);
1425         if (rc) {
1426                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1427                        rc);
1428                 goto out_free;
1429         }
1430         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1431                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1432                 rc = -EINVAL;
1433                 goto out_free;
1434         }
1435         (*packet_size) += length_size;
1436         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1437                 printk(KERN_ERR "Packet size exceeds max\n");
1438                 rc = -EINVAL;
1439                 goto out_free;
1440         }
1441         (*new_auth_tok)->session_key.encrypted_key_size =
1442                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1443         if ((*new_auth_tok)->session_key.encrypted_key_size
1444             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1445                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1446                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1447                 rc = -EINVAL;
1448                 goto out_free;
1449         }
1450         if (unlikely(data[(*packet_size)++] != 0x04)) {
1451                 printk(KERN_WARNING "Unknown version number [%d]\n",
1452                        data[(*packet_size) - 1]);
1453                 rc = -EINVAL;
1454                 goto out_free;
1455         }
1456         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1457                                             (u16)data[(*packet_size)]);
1458         if (rc)
1459                 goto out_free;
1460         /* A little extra work to differentiate among the AES key
1461          * sizes; see RFC2440 */
1462         switch(data[(*packet_size)++]) {
1463         case RFC2440_CIPHER_AES_192:
1464                 crypt_stat->key_size = 24;
1465                 break;
1466         default:
1467                 crypt_stat->key_size =
1468                         (*new_auth_tok)->session_key.encrypted_key_size;
1469         }
1470         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1471         if (rc)
1472                 goto out_free;
1473         if (unlikely(data[(*packet_size)++] != 0x03)) {
1474                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1475                 rc = -ENOSYS;
1476                 goto out_free;
1477         }
1478         /* TODO: finish the hash mapping */
1479         switch (data[(*packet_size)++]) {
1480         case 0x01: /* See RFC2440 for these numbers and their mappings */
1481                 /* Choose MD5 */
1482                 memcpy((*new_auth_tok)->token.password.salt,
1483                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1484                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1485                 /* This conversion was taken straight from RFC2440 */
1486                 (*new_auth_tok)->token.password.hash_iterations =
1487                         ((u32) 16 + (data[(*packet_size)] & 15))
1488                                 << ((data[(*packet_size)] >> 4) + 6);
1489                 (*packet_size)++;
1490                 /* Friendly reminder:
1491                  * (*new_auth_tok)->session_key.encrypted_key_size =
1492                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1493                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1494                        &data[(*packet_size)],
1495                        (*new_auth_tok)->session_key.encrypted_key_size);
1496                 (*packet_size) +=
1497                         (*new_auth_tok)->session_key.encrypted_key_size;
1498                 (*new_auth_tok)->session_key.flags &=
1499                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1500                 (*new_auth_tok)->session_key.flags |=
1501                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1502                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1503                 break;
1504         default:
1505                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1506                                 "[%d]\n", data[(*packet_size) - 1]);
1507                 rc = -ENOSYS;
1508                 goto out_free;
1509         }
1510         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1511         /* TODO: Parametarize; we might actually want userspace to
1512          * decrypt the session key. */
1513         (*new_auth_tok)->session_key.flags &=
1514                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1515         (*new_auth_tok)->session_key.flags &=
1516                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1517         list_add(&auth_tok_list_item->list, auth_tok_list);
1518         goto out;
1519 out_free:
1520         (*new_auth_tok) = NULL;
1521         memset(auth_tok_list_item, 0,
1522                sizeof(struct ecryptfs_auth_tok_list_item));
1523         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1524                         auth_tok_list_item);
1525 out:
1526         if (rc)
1527                 (*packet_size) = 0;
1528         return rc;
1529 }
1530
1531 /**
1532  * parse_tag_11_packet
1533  * @data: The raw bytes of the packet
1534  * @contents: This function writes the data contents of the literal
1535  *            packet into this memory location
1536  * @max_contents_bytes: The maximum number of bytes that this function
1537  *                      is allowed to write into contents
1538  * @tag_11_contents_size: This function writes the size of the parsed
1539  *                        contents into this memory location; zero on
1540  *                        error
1541  * @packet_size: This function writes the size of the parsed packet
1542  *               into this memory location; zero on error
1543  * @max_packet_size: maximum number of bytes to parse
1544  *
1545  * Returns zero on success; non-zero on error.
1546  */
1547 static int
1548 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1549                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1550                     size_t *packet_size, size_t max_packet_size)
1551 {
1552         size_t body_size;
1553         size_t length_size;
1554         int rc = 0;
1555
1556         (*packet_size) = 0;
1557         (*tag_11_contents_size) = 0;
1558         /* This format is inspired by OpenPGP; see RFC 2440
1559          * packet tag 11
1560          *
1561          * Tag 11 identifier (1 byte)
1562          * Max Tag 11 packet size (max 3 bytes)
1563          * Binary format specifier (1 byte)
1564          * Filename length (1 byte)
1565          * Filename ("_CONSOLE") (8 bytes)
1566          * Modification date (4 bytes)
1567          * Literal data (arbitrary)
1568          *
1569          * We need at least 16 bytes of data for the packet to even be
1570          * valid.
1571          */
1572         if (max_packet_size < 16) {
1573                 printk(KERN_ERR "Maximum packet size too small\n");
1574                 rc = -EINVAL;
1575                 goto out;
1576         }
1577         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1578                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1579                 rc = -EINVAL;
1580                 goto out;
1581         }
1582         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1583                                           &length_size);
1584         if (rc) {
1585                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1586                 goto out;
1587         }
1588         if (body_size < 14) {
1589                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1590                 rc = -EINVAL;
1591                 goto out;
1592         }
1593         (*packet_size) += length_size;
1594         (*tag_11_contents_size) = (body_size - 14);
1595         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1596                 printk(KERN_ERR "Packet size exceeds max\n");
1597                 rc = -EINVAL;
1598                 goto out;
1599         }
1600         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1601                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1602                        "expected size\n");
1603                 rc = -EINVAL;
1604                 goto out;
1605         }
1606         if (data[(*packet_size)++] != 0x62) {
1607                 printk(KERN_WARNING "Unrecognizable packet\n");
1608                 rc = -EINVAL;
1609                 goto out;
1610         }
1611         if (data[(*packet_size)++] != 0x08) {
1612                 printk(KERN_WARNING "Unrecognizable packet\n");
1613                 rc = -EINVAL;
1614                 goto out;
1615         }
1616         (*packet_size) += 12; /* Ignore filename and modification date */
1617         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1618         (*packet_size) += (*tag_11_contents_size);
1619 out:
1620         if (rc) {
1621                 (*packet_size) = 0;
1622                 (*tag_11_contents_size) = 0;
1623         }
1624         return rc;
1625 }
1626
1627 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1628                                       struct ecryptfs_auth_tok **auth_tok,
1629                                       char *sig)
1630 {
1631         int rc = 0;
1632
1633         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1634         if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1635                 printk(KERN_ERR "Could not find key with description: [%s]\n",
1636                        sig);
1637                 rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1638                 (*auth_tok_key) = NULL;
1639                 goto out;
1640         }
1641
1642         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1643         if (rc) {
1644                 key_put(*auth_tok_key);
1645                 (*auth_tok_key) = NULL;
1646                 goto out;
1647         }
1648 out:
1649         return rc;
1650 }
1651
1652 /**
1653  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1654  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1655  * @crypt_stat: The cryptographic context
1656  *
1657  * Returns zero on success; non-zero error otherwise
1658  */
1659 static int
1660 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1661                                          struct ecryptfs_crypt_stat *crypt_stat)
1662 {
1663         struct scatterlist dst_sg[2];
1664         struct scatterlist src_sg[2];
1665         struct mutex *tfm_mutex;
1666         struct blkcipher_desc desc = {
1667                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
1668         };
1669         int rc = 0;
1670
1671         if (unlikely(ecryptfs_verbosity > 0)) {
1672                 ecryptfs_printk(
1673                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1674                         auth_tok->token.password.session_key_encryption_key_bytes);
1675                 ecryptfs_dump_hex(
1676                         auth_tok->token.password.session_key_encryption_key,
1677                         auth_tok->token.password.session_key_encryption_key_bytes);
1678         }
1679         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
1680                                                         crypt_stat->cipher);
1681         if (unlikely(rc)) {
1682                 printk(KERN_ERR "Internal error whilst attempting to get "
1683                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1684                        crypt_stat->cipher, rc);
1685                 goto out;
1686         }
1687         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1688                                  auth_tok->session_key.encrypted_key_size,
1689                                  src_sg, 2);
1690         if (rc < 1 || rc > 2) {
1691                 printk(KERN_ERR "Internal error whilst attempting to convert "
1692                         "auth_tok->session_key.encrypted_key to scatterlist; "
1693                         "expected rc = 1; got rc = [%d]. "
1694                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1695                         auth_tok->session_key.encrypted_key_size);
1696                 goto out;
1697         }
1698         auth_tok->session_key.decrypted_key_size =
1699                 auth_tok->session_key.encrypted_key_size;
1700         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1701                                  auth_tok->session_key.decrypted_key_size,
1702                                  dst_sg, 2);
1703         if (rc < 1 || rc > 2) {
1704                 printk(KERN_ERR "Internal error whilst attempting to convert "
1705                         "auth_tok->session_key.decrypted_key to scatterlist; "
1706                         "expected rc = 1; got rc = [%d]\n", rc);
1707                 goto out;
1708         }
1709         mutex_lock(tfm_mutex);
1710         rc = crypto_blkcipher_setkey(
1711                 desc.tfm, auth_tok->token.password.session_key_encryption_key,
1712                 crypt_stat->key_size);
1713         if (unlikely(rc < 0)) {
1714                 mutex_unlock(tfm_mutex);
1715                 printk(KERN_ERR "Error setting key for crypto context\n");
1716                 rc = -EINVAL;
1717                 goto out;
1718         }
1719         rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
1720                                       auth_tok->session_key.encrypted_key_size);
1721         mutex_unlock(tfm_mutex);
1722         if (unlikely(rc)) {
1723                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1724                 goto out;
1725         }
1726         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1727         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1728                auth_tok->session_key.decrypted_key_size);
1729         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1730         if (unlikely(ecryptfs_verbosity > 0)) {
1731                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1732                                 crypt_stat->key_size);
1733                 ecryptfs_dump_hex(crypt_stat->key,
1734                                   crypt_stat->key_size);
1735         }
1736 out:
1737         return rc;
1738 }
1739
1740 /**
1741  * ecryptfs_parse_packet_set
1742  * @crypt_stat: The cryptographic context
1743  * @src: Virtual address of region of memory containing the packets
1744  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1745  *
1746  * Get crypt_stat to have the file's session key if the requisite key
1747  * is available to decrypt the session key.
1748  *
1749  * Returns Zero if a valid authentication token was retrieved and
1750  * processed; negative value for file not encrypted or for error
1751  * conditions.
1752  */
1753 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1754                               unsigned char *src,
1755                               struct dentry *ecryptfs_dentry)
1756 {
1757         size_t i = 0;
1758         size_t found_auth_tok;
1759         size_t next_packet_is_auth_tok_packet;
1760         struct list_head auth_tok_list;
1761         struct ecryptfs_auth_tok *matching_auth_tok;
1762         struct ecryptfs_auth_tok *candidate_auth_tok;
1763         char *candidate_auth_tok_sig;
1764         size_t packet_size;
1765         struct ecryptfs_auth_tok *new_auth_tok;
1766         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1767         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1768         size_t tag_11_contents_size;
1769         size_t tag_11_packet_size;
1770         struct key *auth_tok_key = NULL;
1771         int rc = 0;
1772
1773         INIT_LIST_HEAD(&auth_tok_list);
1774         /* Parse the header to find as many packets as we can; these will be
1775          * added the our &auth_tok_list */
1776         next_packet_is_auth_tok_packet = 1;
1777         while (next_packet_is_auth_tok_packet) {
1778                 size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
1779
1780                 switch (src[i]) {
1781                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1782                         rc = parse_tag_3_packet(crypt_stat,
1783                                                 (unsigned char *)&src[i],
1784                                                 &auth_tok_list, &new_auth_tok,
1785                                                 &packet_size, max_packet_size);
1786                         if (rc) {
1787                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1788                                                 "tag 3 packet\n");
1789                                 rc = -EIO;
1790                                 goto out_wipe_list;
1791                         }
1792                         i += packet_size;
1793                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1794                                                  sig_tmp_space,
1795                                                  ECRYPTFS_SIG_SIZE,
1796                                                  &tag_11_contents_size,
1797                                                  &tag_11_packet_size,
1798                                                  max_packet_size);
1799                         if (rc) {
1800                                 ecryptfs_printk(KERN_ERR, "No valid "
1801                                                 "(ecryptfs-specific) literal "
1802                                                 "packet containing "
1803                                                 "authentication token "
1804                                                 "signature found after "
1805                                                 "tag 3 packet\n");
1806                                 rc = -EIO;
1807                                 goto out_wipe_list;
1808                         }
1809                         i += tag_11_packet_size;
1810                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1811                                 ecryptfs_printk(KERN_ERR, "Expected "
1812                                                 "signature of size [%d]; "
1813                                                 "read size [%zd]\n",
1814                                                 ECRYPTFS_SIG_SIZE,
1815                                                 tag_11_contents_size);
1816                                 rc = -EIO;
1817                                 goto out_wipe_list;
1818                         }
1819                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1820                                         sig_tmp_space, tag_11_contents_size);
1821                         new_auth_tok->token.password.signature[
1822                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1823                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1824                         break;
1825                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1826                         rc = parse_tag_1_packet(crypt_stat,
1827                                                 (unsigned char *)&src[i],
1828                                                 &auth_tok_list, &new_auth_tok,
1829                                                 &packet_size, max_packet_size);
1830                         if (rc) {
1831                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1832                                                 "tag 1 packet\n");
1833                                 rc = -EIO;
1834                                 goto out_wipe_list;
1835                         }
1836                         i += packet_size;
1837                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1838                         break;
1839                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1840                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1841                                         "(Tag 11 not allowed by itself)\n");
1842                         rc = -EIO;
1843                         goto out_wipe_list;
1844                         break;
1845                 default:
1846                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1847                                         "of the file header; hex value of "
1848                                         "character is [0x%.2x]\n", i, src[i]);
1849                         next_packet_is_auth_tok_packet = 0;
1850                 }
1851         }
1852         if (list_empty(&auth_tok_list)) {
1853                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1854                        "eCryptfs file; this is not supported in this version "
1855                        "of the eCryptfs kernel module\n");
1856                 rc = -EINVAL;
1857                 goto out;
1858         }
1859         /* auth_tok_list contains the set of authentication tokens
1860          * parsed from the metadata. We need to find a matching
1861          * authentication token that has the secret component(s)
1862          * necessary to decrypt the EFEK in the auth_tok parsed from
1863          * the metadata. There may be several potential matches, but
1864          * just one will be sufficient to decrypt to get the FEK. */
1865 find_next_matching_auth_tok:
1866         found_auth_tok = 0;
1867         if (auth_tok_key) {
1868                 key_put(auth_tok_key);
1869                 auth_tok_key = NULL;
1870         }
1871         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1872                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1873                 if (unlikely(ecryptfs_verbosity > 0)) {
1874                         ecryptfs_printk(KERN_DEBUG,
1875                                         "Considering cadidate auth tok:\n");
1876                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1877                 }
1878                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1879                                                candidate_auth_tok);
1880                 if (rc) {
1881                         printk(KERN_ERR
1882                                "Unrecognized candidate auth tok type: [%d]\n",
1883                                candidate_auth_tok->token_type);
1884                         rc = -EINVAL;
1885                         goto out_wipe_list;
1886                 }
1887                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1888                                                &matching_auth_tok,
1889                                                crypt_stat->mount_crypt_stat,
1890                                                candidate_auth_tok_sig);
1891                 if (!rc) {
1892                         found_auth_tok = 1;
1893                         goto found_matching_auth_tok;
1894                 }
1895         }
1896         if (!found_auth_tok) {
1897                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1898                                 "authentication token\n");
1899                 rc = -EIO;
1900                 goto out_wipe_list;
1901         }
1902 found_matching_auth_tok:
1903         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1904                 memcpy(&(candidate_auth_tok->token.private_key),
1905                        &(matching_auth_tok->token.private_key),
1906                        sizeof(struct ecryptfs_private_key));
1907                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1908                                                        crypt_stat);
1909         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1910                 memcpy(&(candidate_auth_tok->token.password),
1911                        &(matching_auth_tok->token.password),
1912                        sizeof(struct ecryptfs_password));
1913                 rc = decrypt_passphrase_encrypted_session_key(
1914                         candidate_auth_tok, crypt_stat);
1915         }
1916         if (rc) {
1917                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1918
1919                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1920                                 "session key for authentication token with sig "
1921                                 "[%.*s]; rc = [%d]. Removing auth tok "
1922                                 "candidate from the list and searching for "
1923                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1924                                 candidate_auth_tok_sig, rc);
1925                 list_for_each_entry_safe(auth_tok_list_item,
1926                                          auth_tok_list_item_tmp,
1927                                          &auth_tok_list, list) {
1928                         if (candidate_auth_tok
1929                             == &auth_tok_list_item->auth_tok) {
1930                                 list_del(&auth_tok_list_item->list);
1931                                 kmem_cache_free(
1932                                         ecryptfs_auth_tok_list_item_cache,
1933                                         auth_tok_list_item);
1934                                 goto find_next_matching_auth_tok;
1935                         }
1936                 }
1937                 BUG();
1938         }
1939         rc = ecryptfs_compute_root_iv(crypt_stat);
1940         if (rc) {
1941                 ecryptfs_printk(KERN_ERR, "Error computing "
1942                                 "the root IV\n");
1943                 goto out_wipe_list;
1944         }
1945         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1946         if (rc) {
1947                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1948                                 "context for cipher [%s]; rc = [%d]\n",
1949                                 crypt_stat->cipher, rc);
1950         }
1951 out_wipe_list:
1952         wipe_auth_tok_list(&auth_tok_list);
1953 out:
1954         if (auth_tok_key)
1955                 key_put(auth_tok_key);
1956         return rc;
1957 }
1958
1959 static int
1960 pki_encrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
1961                         struct ecryptfs_crypt_stat *crypt_stat,
1962                         struct ecryptfs_key_record *key_rec)
1963 {
1964         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1965         char *payload = NULL;
1966         size_t payload_len;
1967         struct ecryptfs_message *msg;
1968         int rc;
1969
1970         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1971                                  ecryptfs_code_for_cipher_string(
1972                                          crypt_stat->cipher,
1973                                          crypt_stat->key_size),
1974                                  crypt_stat, &payload, &payload_len);
1975         if (rc) {
1976                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1977                 goto out;
1978         }
1979         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1980         if (rc) {
1981                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1982                                 "ecryptfsd\n");
1983                 goto out;
1984         }
1985         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1986         if (rc) {
1987                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1988                                 "from the user space daemon\n");
1989                 rc = -EIO;
1990                 goto out;
1991         }
1992         rc = parse_tag_67_packet(key_rec, msg);
1993         if (rc)
1994                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
1995         kfree(msg);
1996 out:
1997         kfree(payload);
1998         return rc;
1999 }
2000 /**
2001  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2002  * @dest: Buffer into which to write the packet
2003  * @remaining_bytes: Maximum number of bytes that can be writtn
2004  * @auth_tok: The authentication token used for generating the tag 1 packet
2005  * @crypt_stat: The cryptographic context
2006  * @key_rec: The key record struct for the tag 1 packet
2007  * @packet_size: This function will write the number of bytes that end
2008  *               up constituting the packet; set to zero on error
2009  *
2010  * Returns zero on success; non-zero on error.
2011  */
2012 static int
2013 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2014                    struct ecryptfs_auth_tok *auth_tok,
2015                    struct ecryptfs_crypt_stat *crypt_stat,
2016                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2017 {
2018         size_t i;
2019         size_t encrypted_session_key_valid = 0;
2020         size_t packet_size_length;
2021         size_t max_packet_size;
2022         int rc = 0;
2023
2024         (*packet_size) = 0;
2025         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2026                           ECRYPTFS_SIG_SIZE);
2027         encrypted_session_key_valid = 0;
2028         for (i = 0; i < crypt_stat->key_size; i++)
2029                 encrypted_session_key_valid |=
2030                         auth_tok->session_key.encrypted_key[i];
2031         if (encrypted_session_key_valid) {
2032                 memcpy(key_rec->enc_key,
2033                        auth_tok->session_key.encrypted_key,
2034                        auth_tok->session_key.encrypted_key_size);
2035                 goto encrypted_session_key_set;
2036         }
2037         if (auth_tok->session_key.encrypted_key_size == 0)
2038                 auth_tok->session_key.encrypted_key_size =
2039                         auth_tok->token.private_key.key_size;
2040         rc = pki_encrypt_session_key(auth_tok, crypt_stat, key_rec);
2041         if (rc) {
2042                 printk(KERN_ERR "Failed to encrypt session key via a key "
2043                        "module; rc = [%d]\n", rc);
2044                 goto out;
2045         }
2046         if (ecryptfs_verbosity > 0) {
2047                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2048                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2049         }
2050 encrypted_session_key_set:
2051         /* This format is inspired by OpenPGP; see RFC 2440
2052          * packet tag 1 */
2053         max_packet_size = (1                         /* Tag 1 identifier */
2054                            + 3                       /* Max Tag 1 packet size */
2055                            + 1                       /* Version */
2056                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2057                            + 1                       /* Cipher identifier */
2058                            + key_rec->enc_key_size); /* Encrypted key size */
2059         if (max_packet_size > (*remaining_bytes)) {
2060                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2061                        "need up to [%td] bytes, but there are only [%td] "
2062                        "available\n", max_packet_size, (*remaining_bytes));
2063                 rc = -EINVAL;
2064                 goto out;
2065         }
2066         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2067         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2068                                           (max_packet_size - 4),
2069                                           &packet_size_length);
2070         if (rc) {
2071                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2072                                 "header; cannot generate packet length\n");
2073                 goto out;
2074         }
2075         (*packet_size) += packet_size_length;
2076         dest[(*packet_size)++] = 0x03; /* version 3 */
2077         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2078         (*packet_size) += ECRYPTFS_SIG_SIZE;
2079         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2080         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2081                key_rec->enc_key_size);
2082         (*packet_size) += key_rec->enc_key_size;
2083 out:
2084         if (rc)
2085                 (*packet_size) = 0;
2086         else
2087                 (*remaining_bytes) -= (*packet_size);
2088         return rc;
2089 }
2090
2091 /**
2092  * write_tag_11_packet
2093  * @dest: Target into which Tag 11 packet is to be written
2094  * @remaining_bytes: Maximum packet length
2095  * @contents: Byte array of contents to copy in
2096  * @contents_length: Number of bytes in contents
2097  * @packet_length: Length of the Tag 11 packet written; zero on error
2098  *
2099  * Returns zero on success; non-zero on error.
2100  */
2101 static int
2102 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2103                     size_t contents_length, size_t *packet_length)
2104 {
2105         size_t packet_size_length;
2106         size_t max_packet_size;
2107         int rc = 0;
2108
2109         (*packet_length) = 0;
2110         /* This format is inspired by OpenPGP; see RFC 2440
2111          * packet tag 11 */
2112         max_packet_size = (1                   /* Tag 11 identifier */
2113                            + 3                 /* Max Tag 11 packet size */
2114                            + 1                 /* Binary format specifier */
2115                            + 1                 /* Filename length */
2116                            + 8                 /* Filename ("_CONSOLE") */
2117                            + 4                 /* Modification date */
2118                            + contents_length); /* Literal data */
2119         if (max_packet_size > (*remaining_bytes)) {
2120                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2121                        "need up to [%td] bytes, but there are only [%td] "
2122                        "available\n", max_packet_size, (*remaining_bytes));
2123                 rc = -EINVAL;
2124                 goto out;
2125         }
2126         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2127         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2128                                           (max_packet_size - 4),
2129                                           &packet_size_length);
2130         if (rc) {
2131                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2132                        "generate packet length. rc = [%d]\n", rc);
2133                 goto out;
2134         }
2135         (*packet_length) += packet_size_length;
2136         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2137         dest[(*packet_length)++] = 8;
2138         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2139         (*packet_length) += 8;
2140         memset(&dest[(*packet_length)], 0x00, 4);
2141         (*packet_length) += 4;
2142         memcpy(&dest[(*packet_length)], contents, contents_length);
2143         (*packet_length) += contents_length;
2144  out:
2145         if (rc)
2146                 (*packet_length) = 0;
2147         else
2148                 (*remaining_bytes) -= (*packet_length);
2149         return rc;
2150 }
2151
2152 /**
2153  * write_tag_3_packet
2154  * @dest: Buffer into which to write the packet
2155  * @remaining_bytes: Maximum number of bytes that can be written
2156  * @auth_tok: Authentication token
2157  * @crypt_stat: The cryptographic context
2158  * @key_rec: encrypted key
2159  * @packet_size: This function will write the number of bytes that end
2160  *               up constituting the packet; set to zero on error
2161  *
2162  * Returns zero on success; non-zero on error.
2163  */
2164 static int
2165 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2166                    struct ecryptfs_auth_tok *auth_tok,
2167                    struct ecryptfs_crypt_stat *crypt_stat,
2168                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2169 {
2170         size_t i;
2171         size_t encrypted_session_key_valid = 0;
2172         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2173         struct scatterlist dst_sg[2];
2174         struct scatterlist src_sg[2];
2175         struct mutex *tfm_mutex = NULL;
2176         u8 cipher_code;
2177         size_t packet_size_length;
2178         size_t max_packet_size;
2179         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2180                 crypt_stat->mount_crypt_stat;
2181         struct blkcipher_desc desc = {
2182                 .tfm = NULL,
2183                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
2184         };
2185         int rc = 0;
2186
2187         (*packet_size) = 0;
2188         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2189                           ECRYPTFS_SIG_SIZE);
2190         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2191                                                         crypt_stat->cipher);
2192         if (unlikely(rc)) {
2193                 printk(KERN_ERR "Internal error whilst attempting to get "
2194                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2195                        crypt_stat->cipher, rc);
2196                 goto out;
2197         }
2198         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2199                 struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);
2200
2201                 printk(KERN_WARNING "No key size specified at mount; "
2202                        "defaulting to [%d]\n", alg->max_keysize);
2203                 mount_crypt_stat->global_default_cipher_key_size =
2204                         alg->max_keysize;
2205         }
2206         if (crypt_stat->key_size == 0)
2207                 crypt_stat->key_size =
2208                         mount_crypt_stat->global_default_cipher_key_size;
2209         if (auth_tok->session_key.encrypted_key_size == 0)
2210                 auth_tok->session_key.encrypted_key_size =
2211                         crypt_stat->key_size;
2212         if (crypt_stat->key_size == 24
2213             && strcmp("aes", crypt_stat->cipher) == 0) {
2214                 memset((crypt_stat->key + 24), 0, 8);
2215                 auth_tok->session_key.encrypted_key_size = 32;
2216         } else
2217                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2218         key_rec->enc_key_size =
2219                 auth_tok->session_key.encrypted_key_size;
2220         encrypted_session_key_valid = 0;
2221         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2222                 encrypted_session_key_valid |=
2223                         auth_tok->session_key.encrypted_key[i];
2224         if (encrypted_session_key_valid) {
2225                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2226                                 "using auth_tok->session_key.encrypted_key, "
2227                                 "where key_rec->enc_key_size = [%zd]\n",
2228                                 key_rec->enc_key_size);
2229                 memcpy(key_rec->enc_key,
2230                        auth_tok->session_key.encrypted_key,
2231                        key_rec->enc_key_size);
2232                 goto encrypted_session_key_set;
2233         }
2234         if (auth_tok->token.password.flags &
2235             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2236                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2237                                 "session key encryption key of size [%d]\n",
2238                                 auth_tok->token.password.
2239                                 session_key_encryption_key_bytes);
2240                 memcpy(session_key_encryption_key,
2241                        auth_tok->token.password.session_key_encryption_key,
2242                        crypt_stat->key_size);
2243                 ecryptfs_printk(KERN_DEBUG,
2244                                 "Cached session key " "encryption key: \n");
2245                 if (ecryptfs_verbosity > 0)
2246                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2247         }
2248         if (unlikely(ecryptfs_verbosity > 0)) {
2249                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2250                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2251         }
2252         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2253                                  src_sg, 2);
2254         if (rc < 1 || rc > 2) {
2255                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2256                                 "for crypt_stat session key; expected rc = 1; "
2257                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2258                                 rc, key_rec->enc_key_size);
2259                 rc = -ENOMEM;
2260                 goto out;
2261         }
2262         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2263                                  dst_sg, 2);
2264         if (rc < 1 || rc > 2) {
2265                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2266                                 "for crypt_stat encrypted session key; "
2267                                 "expected rc = 1; got rc = [%d]. "
2268                                 "key_rec->enc_key_size = [%zd]\n", rc,
2269                                 key_rec->enc_key_size);
2270                 rc = -ENOMEM;
2271                 goto out;
2272         }
2273         mutex_lock(tfm_mutex);
2274         rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
2275                                      crypt_stat->key_size);
2276         if (rc < 0) {
2277                 mutex_unlock(tfm_mutex);
2278                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2279                                 "context; rc = [%d]\n", rc);
2280                 goto out;
2281         }
2282         rc = 0;
2283         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2284                         crypt_stat->key_size);
2285         rc = crypto_blkcipher_encrypt(&desc, dst_sg, src_sg,
2286                                       (*key_rec).enc_key_size);
2287         mutex_unlock(tfm_mutex);
2288         if (rc) {
2289                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2290                 goto out;
2291         }
2292         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2293         if (ecryptfs_verbosity > 0) {
2294                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2295                                 key_rec->enc_key_size);
2296                 ecryptfs_dump_hex(key_rec->enc_key,
2297                                   key_rec->enc_key_size);
2298         }
2299 encrypted_session_key_set:
2300         /* This format is inspired by OpenPGP; see RFC 2440
2301          * packet tag 3 */
2302         max_packet_size = (1                         /* Tag 3 identifier */
2303                            + 3                       /* Max Tag 3 packet size */
2304                            + 1                       /* Version */
2305                            + 1                       /* Cipher code */
2306                            + 1                       /* S2K specifier */
2307                            + 1                       /* Hash identifier */
2308                            + ECRYPTFS_SALT_SIZE      /* Salt */
2309                            + 1                       /* Hash iterations */
2310                            + key_rec->enc_key_size); /* Encrypted key size */
2311         if (max_packet_size > (*remaining_bytes)) {
2312                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2313                        "there are only [%td] available\n", max_packet_size,
2314                        (*remaining_bytes));
2315                 rc = -EINVAL;
2316                 goto out;
2317         }
2318         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2319         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2320          * to get the number of octets in the actual Tag 3 packet */
2321         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2322                                           (max_packet_size - 4),
2323                                           &packet_size_length);
2324         if (rc) {
2325                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2326                        "generate packet length. rc = [%d]\n", rc);
2327                 goto out;
2328         }
2329         (*packet_size) += packet_size_length;
2330         dest[(*packet_size)++] = 0x04; /* version 4 */
2331         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2332          * specified with strings */
2333         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2334                                                       crypt_stat->key_size);
2335         if (cipher_code == 0) {
2336                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2337                                 "cipher [%s]\n", crypt_stat->cipher);
2338                 rc = -EINVAL;
2339                 goto out;
2340         }
2341         dest[(*packet_size)++] = cipher_code;
2342         dest[(*packet_size)++] = 0x03;  /* S2K */
2343         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2344         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2345                ECRYPTFS_SALT_SIZE);
2346         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2347         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2348         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2349                key_rec->enc_key_size);
2350         (*packet_size) += key_rec->enc_key_size;
2351 out:
2352         if (rc)
2353                 (*packet_size) = 0;
2354         else
2355                 (*remaining_bytes) -= (*packet_size);
2356         return rc;
2357 }
2358
2359 struct kmem_cache *ecryptfs_key_record_cache;
2360
2361 /**
2362  * ecryptfs_generate_key_packet_set
2363  * @dest_base: Virtual address from which to write the key record set
2364  * @crypt_stat: The cryptographic context from which the
2365  *              authentication tokens will be retrieved
2366  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2367  *                   for the global parameters
2368  * @len: The amount written
2369  * @max: The maximum amount of data allowed to be written
2370  *
2371  * Generates a key packet set and writes it to the virtual address
2372  * passed in.
2373  *
2374  * Returns zero on success; non-zero on error.
2375  */
2376 int
2377 ecryptfs_generate_key_packet_set(char *dest_base,
2378                                  struct ecryptfs_crypt_stat *crypt_stat,
2379                                  struct dentry *ecryptfs_dentry, size_t *len,
2380                                  size_t max)
2381 {
2382         struct ecryptfs_auth_tok *auth_tok;
2383         struct key *auth_tok_key = NULL;
2384         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2385                 &ecryptfs_superblock_to_private(
2386                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2387         size_t written;
2388         struct ecryptfs_key_record *key_rec;
2389         struct ecryptfs_key_sig *key_sig;
2390         int rc = 0;
2391
2392         (*len) = 0;
2393         mutex_lock(&crypt_stat->keysig_list_mutex);
2394         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2395         if (!key_rec) {
2396                 rc = -ENOMEM;
2397                 goto out;
2398         }
2399         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2400                             crypt_stat_list) {
2401                 memset(key_rec, 0, sizeof(*key_rec));
2402                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2403                                                            &auth_tok,
2404                                                            mount_crypt_stat,
2405                                                            key_sig->keysig);
2406                 if (rc) {
2407                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2408                                "sig = [%s]\n", key_sig->keysig);
2409                         rc = process_find_global_auth_tok_for_sig_err(rc);
2410                         goto out_free;
2411                 }
2412                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2413                         rc = write_tag_3_packet((dest_base + (*len)),
2414                                                 &max, auth_tok,
2415                                                 crypt_stat, key_rec,
2416                                                 &written);
2417                         if (rc) {
2418                                 ecryptfs_printk(KERN_WARNING, "Error "
2419                                                 "writing tag 3 packet\n");
2420                                 goto out_free;
2421                         }
2422                         (*len) += written;
2423                         /* Write auth tok signature packet */
2424                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2425                                                  key_rec->sig,
2426                                                  ECRYPTFS_SIG_SIZE, &written);
2427                         if (rc) {
2428                                 ecryptfs_printk(KERN_ERR, "Error writing "
2429                                                 "auth tok signature packet\n");
2430                                 goto out_free;
2431                         }
2432                         (*len) += written;
2433                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2434                         rc = write_tag_1_packet(dest_base + (*len),
2435                                                 &max, auth_tok,
2436                                                 crypt_stat, key_rec, &written);
2437                         if (rc) {
2438                                 ecryptfs_printk(KERN_WARNING, "Error "
2439                                                 "writing tag 1 packet\n");
2440                                 goto out_free;
2441                         }
2442                         (*len) += written;
2443                 } else {
2444                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2445                                         "authentication token type\n");
2446                         rc = -EINVAL;
2447                         goto out_free;
2448                 }
2449                 key_put(auth_tok_key);
2450                 auth_tok_key = NULL;
2451         }
2452         if (likely(max > 0)) {
2453                 dest_base[(*len)] = 0x00;
2454         } else {
2455                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2456                 rc = -EIO;
2457         }
2458 out_free:
2459         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2460 out:
2461         if (rc)
2462                 (*len) = 0;
2463         if (auth_tok_key)
2464                 key_put(auth_tok_key);
2465
2466         mutex_unlock(&crypt_stat->keysig_list_mutex);
2467         return rc;
2468 }
2469
2470 struct kmem_cache *ecryptfs_key_sig_cache;
2471
2472 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2473 {
2474         struct ecryptfs_key_sig *new_key_sig;
2475
2476         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2477         if (!new_key_sig) {
2478                 printk(KERN_ERR
2479                        "Error allocating from ecryptfs_key_sig_cache\n");
2480                 return -ENOMEM;
2481         }
2482         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2483         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2484         /* Caller must hold keysig_list_mutex */
2485         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2486
2487         return 0;
2488 }
2489
2490 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2491
2492 int
2493 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2494                              char *sig, u32 global_auth_tok_flags)
2495 {
2496         struct ecryptfs_global_auth_tok *new_auth_tok;
2497         int rc = 0;
2498
2499         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2500                                         GFP_KERNEL);
2501         if (!new_auth_tok) {
2502                 rc = -ENOMEM;
2503                 printk(KERN_ERR "Error allocating from "
2504                        "ecryptfs_global_auth_tok_cache\n");
2505                 goto out;
2506         }
2507         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2508         new_auth_tok->flags = global_auth_tok_flags;
2509         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2510         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2511         list_add(&new_auth_tok->mount_crypt_stat_list,
2512                  &mount_crypt_stat->global_auth_tok_list);
2513         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2514 out:
2515         return rc;
2516 }
2517