fs/ecryptfs/keystore.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * eCryptfs: Linux filesystem encryption layer
   4  * In-kernel key management code.  Includes functions to parse and
   5  * write authentication token-related packets with the underlying
   6  * file.
   7  *
   8  * Copyright (C) 2004-2006 International Business Machines Corp.
   9  *   Author(s): Michael A. Halcrow <[email protected]>
  10  *              Michael C. Thompson <[email protected]>
  11  *              Trevor S. Highland <[email protected]>
  12  */
  13
  14 #include <crypto/hash.h>
  15 #include <crypto/skcipher.h>
  16 #include <linux/string.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/key.h>
  19 #include <linux/random.h>
  20 #include <linux/scatterlist.h>
  21 #include <linux/slab.h>
  22 #include "ecryptfs_kernel.h"
  23
  24 /*
  25  * request_key returned an error instead of a valid key address;
  26  * determine the type of error, make appropriate log entries, and
  27  * return an error code.
  28  */
  29 static int process_request_key_err(long err_code)
  30 {
  31         int rc = 0;
  32
  33         switch (err_code) {
  34         case -ENOKEY:
  35                 ecryptfs_printk(KERN_WARNING, "No key\n");
  36                 rc = -ENOENT;
  37                 break;
  38         case -EKEYEXPIRED:
  39                 ecryptfs_printk(KERN_WARNING, "Key expired\n");
  40                 rc = -ETIME;
  41                 break;
  42         case -EKEYREVOKED:
  43                 ecryptfs_printk(KERN_WARNING, "Key revoked\n");
  44                 rc = -EINVAL;
  45                 break;
  46         default:
  47                 ecryptfs_printk(KERN_WARNING, "Unknown error code: "
  48                                 "[0x%.16lx]\n", err_code);
  49                 rc = -EINVAL;
  50         }
  51         return rc;
  52 }
  53
  54 static int process_find_global_auth_tok_for_sig_err(int err_code)
  55 {
  56         int rc = err_code;
  57
  58         switch (err_code) {
  59         case -ENOENT:
  60                 ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
  61                 break;
  62         case -EINVAL:
  63                 ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
  64                 break;
  65         default:
  66                 rc = process_request_key_err(err_code);
  67                 break;
  68         }
  69         return rc;
  70 }
  71
  72 /**
  73  * ecryptfs_parse_packet_length
  74  * @data: Pointer to memory containing length at offset
  75  * @size: This function writes the decoded size to this memory
  76  *        address; zero on error
  77  * @length_size: The number of bytes occupied by the encoded length
  78  *
  79  * Returns zero on success; non-zero on error
  80  */
  81 int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
  82                                  size_t *length_size)
  83 {
  84         int rc = 0;
  85
  86         (*length_size) = 0;
  87         (*size) = 0;
  88         if (data[0] < 192) {
  89                 /* One-byte length */
  90                 (*size) = data[0];
  91                 (*length_size) = 1;
  92         } else if (data[0] < 224) {
  93                 /* Two-byte length */
  94                 (*size) = (data[0] - 192) * 256;
  95                 (*size) += data[1] + 192;
  96                 (*length_size) = 2;
  97         } else if (data[0] == 255) {
  98                 /* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
  99                 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
 100                                 "supported\n");
 101                 rc = -EINVAL;
 102                 goto out;
 103         } else {
 104                 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
 105                 rc = -EINVAL;
 106                 goto out;
 107         }
 108 out:
 109         return rc;
 110 }
 111
 112 /**
 113  * ecryptfs_write_packet_length
 114  * @dest: The byte array target into which to write the length. Must
 115  *        have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
 116  * @size: The length to write.
 117  * @packet_size_length: The number of bytes used to encode the packet
 118  *                      length is written to this address.
 119  *
 120  * Returns zero on success; non-zero on error.
 121  */
 122 int ecryptfs_write_packet_length(char *dest, size_t size,
 123                                  size_t *packet_size_length)
 124 {
 125         int rc = 0;
 126
 127         if (size < 192) {
 128                 dest[0] = size;
 129                 (*packet_size_length) = 1;
 130         } else if (size < 65536) {
 131                 dest[0] = (((size - 192) / 256) + 192);
 132                 dest[1] = ((size - 192) % 256);
 133                 (*packet_size_length) = 2;
 134         } else {
 135                 /* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
 136                 rc = -EINVAL;
 137                 ecryptfs_printk(KERN_WARNING,
 138                                 "Unsupported packet size: [%zd]\n", size);
 139         }
 140         return rc;
 141 }
 142
 143 static int
 144 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
 145                     char **packet, size_t *packet_len)
 146 {
 147         size_t i = 0;
 148         size_t data_len;
 149         size_t packet_size_len;
 150         char *message;
 151         int rc;
 152
 153         /*
 154          *              ***** TAG 64 Packet Format *****
 155          *    | Content Type                       | 1 byte       |
 156          *    | Key Identifier Size                | 1 or 2 bytes |
 157          *    | Key Identifier                     | arbitrary    |
 158          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 159          *    | Encrypted File Encryption Key      | arbitrary    |
 160          */
 161         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
 162                     + session_key->encrypted_key_size);
 163         *packet = kmalloc(data_len, GFP_KERNEL);
 164         message = *packet;
 165         if (!message) {
 166                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 167                 rc = -ENOMEM;
 168                 goto out;
 169         }
 170         message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
 171         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 172                                           &packet_size_len);
 173         if (rc) {
 174                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 175                                 "header; cannot generate packet length\n");
 176                 goto out;
 177         }
 178         i += packet_size_len;
 179         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 180         i += ECRYPTFS_SIG_SIZE_HEX;
 181         rc = ecryptfs_write_packet_length(&message[i],
 182                                           session_key->encrypted_key_size,
 183                                           &packet_size_len);
 184         if (rc) {
 185                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 186                                 "header; cannot generate packet length\n");
 187                 goto out;
 188         }
 189         i += packet_size_len;
 190         memcpy(&message[i], session_key->encrypted_key,
 191                session_key->encrypted_key_size);
 192         i += session_key->encrypted_key_size;
 193         *packet_len = i;
 194 out:
 195         return rc;
 196 }
 197
 198 static int
 199 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
 200                     struct ecryptfs_message *msg)
 201 {
 202         size_t i = 0;
 203         char *data;
 204         size_t data_len;
 205         size_t m_size;
 206         size_t message_len;
 207         u16 checksum = 0;
 208         u16 expected_checksum = 0;
 209         int rc;
 210
 211         /*
 212          *              ***** TAG 65 Packet Format *****
 213          *         | Content Type             | 1 byte       |
 214          *         | Status Indicator         | 1 byte       |
 215          *         | File Encryption Key Size | 1 or 2 bytes |
 216          *         | File Encryption Key      | arbitrary    |
 217          */
 218         message_len = msg->data_len;
 219         data = msg->data;
 220         if (message_len < 4) {
 221                 rc = -EIO;
 222                 goto out;
 223         }
 224         if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
 225                 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
 226                 rc = -EIO;
 227                 goto out;
 228         }
 229         if (data[i++]) {
 230                 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
 231                                 "[%d]\n", data[i-1]);
 232                 rc = -EIO;
 233                 goto out;
 234         }
 235         rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
 236         if (rc) {
 237                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 238                                 "rc = [%d]\n", rc);
 239                 goto out;
 240         }
 241         i += data_len;
 242         if (message_len < (i + m_size)) {
 243                 ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
 244                                 "is shorter than expected\n");
 245                 rc = -EIO;
 246                 goto out;
 247         }
 248         if (m_size < 3) {
 249                 ecryptfs_printk(KERN_ERR,
 250                                 "The decrypted key is not long enough to "
 251                                 "include a cipher code and checksum\n");
 252                 rc = -EIO;
 253                 goto out;
 254         }
 255         *cipher_code = data[i++];
 256         /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
 257         session_key->decrypted_key_size = m_size - 3;
 258         if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
 259                 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
 260                                 "the maximum key size [%d]\n",
 261                                 session_key->decrypted_key_size,
 262                                 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 263                 rc = -EIO;
 264                 goto out;
 265         }
 266         memcpy(session_key->decrypted_key, &data[i],
 267                session_key->decrypted_key_size);
 268         i += session_key->decrypted_key_size;
 269         expected_checksum += (unsigned char)(data[i++]) << 8;
 270         expected_checksum += (unsigned char)(data[i++]);
 271         for (i = 0; i < session_key->decrypted_key_size; i++)
 272                 checksum += session_key->decrypted_key[i];
 273         if (expected_checksum != checksum) {
 274                 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
 275                                 "encryption  key; expected [%x]; calculated "
 276                                 "[%x]\n", expected_checksum, checksum);
 277                 rc = -EIO;
 278         }
 279 out:
 280         return rc;
 281 }
 282
 283
 284 static int
 285 write_tag_66_packet(char *signature, u8 cipher_code,
 286                     struct ecryptfs_crypt_stat *crypt_stat, char **packet,
 287                     size_t *packet_len)
 288 {
 289         size_t i = 0;
 290         size_t j;
 291         size_t data_len;
 292         size_t checksum = 0;
 293         size_t packet_size_len;
 294         char *message;
 295         int rc;
 296
 297         /*
 298          *              ***** TAG 66 Packet Format *****
 299          *         | Content Type             | 1 byte       |
 300          *         | Key Identifier Size      | 1 or 2 bytes |
 301          *         | Key Identifier           | arbitrary    |
 302          *         | File Encryption Key Size | 1 or 2 bytes |
 303          *         | Cipher Code              | 1 byte       |
 304          *         | File Encryption Key      | arbitrary    |
 305          *         | Checksum                 | 2 bytes      |
 306          */
 307         data_len = (8 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
 308         *packet = kmalloc(data_len, GFP_KERNEL);
 309         message = *packet;
 310         if (!message) {
 311                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 312                 rc = -ENOMEM;
 313                 goto out;
 314         }
 315         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
 316         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 317                                           &packet_size_len);
 318         if (rc) {
 319                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 320                                 "header; cannot generate packet length\n");
 321                 goto out;
 322         }
 323         i += packet_size_len;
 324         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 325         i += ECRYPTFS_SIG_SIZE_HEX;
 326         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
 327         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
 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         message[i++] = cipher_code;
 336         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
 337         i += crypt_stat->key_size;
 338         for (j = 0; j < crypt_stat->key_size; j++)
 339                 checksum += crypt_stat->key[j];
 340         message[i++] = (checksum / 256) % 256;
 341         message[i++] = (checksum % 256);
 342         *packet_len = i;
 343 out:
 344         return rc;
 345 }
 346
 347 static int
 348 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
 349                     struct ecryptfs_message *msg)
 350 {
 351         size_t i = 0;
 352         char *data;
 353         size_t data_len;
 354         size_t message_len;
 355         int rc;
 356
 357         /*
 358          *              ***** TAG 65 Packet Format *****
 359          *    | Content Type                       | 1 byte       |
 360          *    | Status Indicator                   | 1 byte       |
 361          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 362          *    | Encrypted File Encryption Key      | arbitrary    |
 363          */
 364         message_len = msg->data_len;
 365         data = msg->data;
 366         /* verify that everything through the encrypted FEK size is present */
 367         if (message_len < 4) {
 368                 rc = -EIO;
 369                 printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
 370                        "message length is [%d]\n", __func__, message_len, 4);
 371                 goto out;
 372         }
 373         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
 374                 rc = -EIO;
 375                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
 376                        __func__);
 377                 goto out;
 378         }
 379         if (data[i++]) {
 380                 rc = -EIO;
 381                 printk(KERN_ERR "%s: Status indicator has non zero "
 382                        "value [%d]\n", __func__, data[i-1]);
 383
 384                 goto out;
 385         }
 386         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
 387                                           &data_len);
 388         if (rc) {
 389                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 390                                 "rc = [%d]\n", rc);
 391                 goto out;
 392         }
 393         i += data_len;
 394         if (message_len < (i + key_rec->enc_key_size)) {
 395                 rc = -EIO;
 396                 printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
 397                        __func__, message_len, (i + key_rec->enc_key_size));
 398                 goto out;
 399         }
 400         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
 401                 rc = -EIO;
 402                 printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
 403                        "the maximum key size [%d]\n", __func__,
 404                        key_rec->enc_key_size,
 405                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 406                 goto out;
 407         }
 408         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
 409 out:
 410         return rc;
 411 }
 412
 413 /**
 414  * ecryptfs_verify_version
 415  * @version: The version number to confirm
 416  *
 417  * Returns zero on good version; non-zero otherwise
 418  */
 419 static int ecryptfs_verify_version(u16 version)
 420 {
 421         int rc = 0;
 422         unsigned char major;
 423         unsigned char minor;
 424
 425         major = ((version >> 8) & 0xFF);
 426         minor = (version & 0xFF);
 427         if (major != ECRYPTFS_VERSION_MAJOR) {
 428                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
 429                                 "Expected [%d]; got [%d]\n",
 430                                 ECRYPTFS_VERSION_MAJOR, major);
 431                 rc = -EINVAL;
 432                 goto out;
 433         }
 434         if (minor != ECRYPTFS_VERSION_MINOR) {
 435                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
 436                                 "Expected [%d]; got [%d]\n",
 437                                 ECRYPTFS_VERSION_MINOR, minor);
 438                 rc = -EINVAL;
 439                 goto out;
 440         }
 441 out:
 442         return rc;
 443 }
 444
 445 /**
 446  * ecryptfs_verify_auth_tok_from_key
 447  * @auth_tok_key: key containing the authentication token
 448  * @auth_tok: authentication token
 449  *
 450  * Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
 451  * -EKEYREVOKED if the key was revoked before we acquired its semaphore.
 452  */
 453 static int
 454 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
 455                                   struct ecryptfs_auth_tok **auth_tok)
 456 {
 457         int rc = 0;
 458
 459         (*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
 460         if (IS_ERR(*auth_tok)) {
 461                 rc = PTR_ERR(*auth_tok);
 462                 *auth_tok = NULL;
 463                 goto out;
 464         }
 465
 466         if (ecryptfs_verify_version((*auth_tok)->version)) {
 467                 printk(KERN_ERR "Data structure version mismatch. Userspace "
 468                        "tools must match eCryptfs kernel module with major "
 469                        "version [%d] and minor version [%d]\n",
 470                        ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
 471                 rc = -EINVAL;
 472                 goto out;
 473         }
 474         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
 475             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
 476                 printk(KERN_ERR "Invalid auth_tok structure "
 477                        "returned from key query\n");
 478                 rc = -EINVAL;
 479                 goto out;
 480         }
 481 out:
 482         return rc;
 483 }
 484
 485 static int
 486 ecryptfs_find_global_auth_tok_for_sig(
 487         struct key **auth_tok_key,
 488         struct ecryptfs_auth_tok **auth_tok,
 489         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
 490 {
 491         struct ecryptfs_global_auth_tok *walker;
 492         int rc = 0;
 493
 494         (*auth_tok_key) = NULL;
 495         (*auth_tok) = NULL;
 496         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 497         list_for_each_entry(walker,
 498                             &mount_crypt_stat->global_auth_tok_list,
 499                             mount_crypt_stat_list) {
 500                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
 501                         continue;
 502
 503                 if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
 504                         rc = -EINVAL;
 505                         goto out;
 506                 }
 507
 508                 rc = key_validate(walker->global_auth_tok_key);
 509                 if (rc) {
 510                         if (rc == -EKEYEXPIRED)
 511                                 goto out;
 512                         goto out_invalid_auth_tok;
 513                 }
 514
 515                 down_write(&(walker->global_auth_tok_key->sem));
 516                 rc = ecryptfs_verify_auth_tok_from_key(
 517                                 walker->global_auth_tok_key, auth_tok);
 518                 if (rc)
 519                         goto out_invalid_auth_tok_unlock;
 520
 521                 (*auth_tok_key) = walker->global_auth_tok_key;
 522                 key_get(*auth_tok_key);
 523                 goto out;
 524         }
 525         rc = -ENOENT;
 526         goto out;
 527 out_invalid_auth_tok_unlock:
 528         up_write(&(walker->global_auth_tok_key->sem));
 529 out_invalid_auth_tok:
 530         printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
 531         walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
 532         key_put(walker->global_auth_tok_key);
 533         walker->global_auth_tok_key = NULL;
 534 out:
 535         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 536         return rc;
 537 }
 538
 539 /**
 540  * ecryptfs_find_auth_tok_for_sig
 541  * @auth_tok_key: key containing the authentication token
 542  * @auth_tok: Set to the matching auth_tok; NULL if not found
 543  * @mount_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[2];
 600         struct scatterlist dst_sg[2];
 601         struct crypto_skcipher *skcipher_tfm;
 602         struct skcipher_request *skcipher_req;
 603         char iv[ECRYPTFS_MAX_IV_BYTES];
 604         char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 605         char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 606         struct crypto_shash *hash_tfm;
 607         struct shash_desc *hash_desc;
 608 };
 609
 610 /*
 611  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
 612  * @filename: NULL-terminated filename string
 613  *
 614  * This is the simplest mechanism for achieving filename encryption in
 615  * eCryptfs. It encrypts the given filename with the mount-wide
 616  * filename encryption key (FNEK) and stores it in a packet to @dest,
 617  * which the callee will encode and write directly into the dentry
 618  * name.
 619  */
 620 int
 621 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 622                              size_t *packet_size,
 623                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 624                              char *filename, size_t filename_size)
 625 {
 626         struct ecryptfs_write_tag_70_packet_silly_stack *s;
 627         struct key *auth_tok_key = NULL;
 628         int rc = 0;
 629
 630         s = kzalloc(sizeof(*s), GFP_KERNEL);
 631         if (!s)
 632                 return -ENOMEM;
 633
 634         (*packet_size) = 0;
 635         rc = ecryptfs_find_auth_tok_for_sig(
 636                 &auth_tok_key,
 637                 &s->auth_tok, mount_crypt_stat,
 638                 mount_crypt_stat->global_default_fnek_sig);
 639         if (rc) {
 640                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 641                        "fnek sig [%s]; rc = [%d]\n", __func__,
 642                        mount_crypt_stat->global_default_fnek_sig, rc);
 643                 goto out;
 644         }
 645         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
 646                 &s->skcipher_tfm,
 647                 &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
 648         if (unlikely(rc)) {
 649                 printk(KERN_ERR "Internal error whilst attempting to get "
 650                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 651                        mount_crypt_stat->global_default_fn_cipher_name, rc);
 652                 goto out;
 653         }
 654         mutex_lock(s->tfm_mutex);
 655         s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
 656         /* Plus one for the \0 separator between the random prefix
 657          * and the plaintext filename */
 658         s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
 659         s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
 660         if ((s->block_aligned_filename_size % s->block_size) != 0) {
 661                 s->num_rand_bytes += (s->block_size
 662                                       - (s->block_aligned_filename_size
 663                                          % s->block_size));
 664                 s->block_aligned_filename_size = (s->num_rand_bytes
 665                                                   + filename_size);
 666         }
 667         /* Octet 0: Tag 70 identifier
 668          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 669          *              and block-aligned encrypted filename size)
 670          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 671          * Octet N2-N3: Cipher identifier (1 octet)
 672          * Octets N3-N4: Block-aligned encrypted filename
 673          *  - Consists of a minimum number of random characters, a \0
 674          *    separator, and then the filename */
 675         s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
 676                               + s->block_aligned_filename_size);
 677         if (!dest) {
 678                 (*packet_size) = s->max_packet_size;
 679                 goto out_unlock;
 680         }
 681         if (s->max_packet_size > (*remaining_bytes)) {
 682                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
 683                        "[%zd] available\n", __func__, s->max_packet_size,
 684                        (*remaining_bytes));
 685                 rc = -EINVAL;
 686                 goto out_unlock;
 687         }
 688
 689         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
 690         if (!s->skcipher_req) {
 691                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
 692                        "skcipher_request_alloc for %s\n", __func__,
 693                        crypto_skcipher_driver_name(s->skcipher_tfm));
 694                 rc = -ENOMEM;
 695                 goto out_unlock;
 696         }
 697
 698         skcipher_request_set_callback(s->skcipher_req,
 699                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 700
 701         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
 702                                             GFP_KERNEL);
 703         if (!s->block_aligned_filename) {
 704                 rc = -ENOMEM;
 705                 goto out_unlock;
 706         }
 707         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
 708         rc = ecryptfs_write_packet_length(&dest[s->i],
 709                                           (ECRYPTFS_SIG_SIZE
 710                                            + 1 /* Cipher code */
 711                                            + s->block_aligned_filename_size),
 712                                           &s->packet_size_len);
 713         if (rc) {
 714                 printk(KERN_ERR "%s: Error generating tag 70 packet "
 715                        "header; cannot generate packet length; rc = [%d]\n",
 716                        __func__, rc);
 717                 goto out_free_unlock;
 718         }
 719         s->i += s->packet_size_len;
 720         ecryptfs_from_hex(&dest[s->i],
 721                           mount_crypt_stat->global_default_fnek_sig,
 722                           ECRYPTFS_SIG_SIZE);
 723         s->i += ECRYPTFS_SIG_SIZE;
 724         s->cipher_code = ecryptfs_code_for_cipher_string(
 725                 mount_crypt_stat->global_default_fn_cipher_name,
 726                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 727         if (s->cipher_code == 0) {
 728                 printk(KERN_WARNING "%s: Unable to generate code for "
 729                        "cipher [%s] with key bytes [%zd]\n", __func__,
 730                        mount_crypt_stat->global_default_fn_cipher_name,
 731                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 732                 rc = -EINVAL;
 733                 goto out_free_unlock;
 734         }
 735         dest[s->i++] = s->cipher_code;
 736         /* TODO: Support other key modules than passphrase for
 737          * filename encryption */
 738         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
 739                 rc = -EOPNOTSUPP;
 740                 printk(KERN_INFO "%s: Filename encryption only supports "
 741                        "password tokens\n", __func__);
 742                 goto out_free_unlock;
 743         }
 744         s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
 745         if (IS_ERR(s->hash_tfm)) {
 746                         rc = PTR_ERR(s->hash_tfm);
 747                         printk(KERN_ERR "%s: Error attempting to "
 748                                "allocate hash crypto context; rc = [%d]\n",
 749                                __func__, rc);
 750                         goto out_free_unlock;
 751         }
 752
 753         s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
 754                                crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
 755         if (!s->hash_desc) {
 756                 rc = -ENOMEM;
 757                 goto out_release_free_unlock;
 758         }
 759
 760         s->hash_desc->tfm = s->hash_tfm;
 761
 762         rc = crypto_shash_digest(s->hash_desc,
 763                                  (u8 *)s->auth_tok->token.password.session_key_encryption_key,
 764                                  s->auth_tok->token.password.session_key_encryption_key_bytes,
 765                                  s->hash);
 766         if (rc) {
 767                 printk(KERN_ERR
 768                        "%s: Error computing crypto hash; rc = [%d]\n",
 769                        __func__, rc);
 770                 goto out_release_free_unlock;
 771         }
 772         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
 773                 s->block_aligned_filename[s->j] =
 774                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
 775                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
 776                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
 777                         rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
 778                                                 ECRYPTFS_TAG_70_DIGEST_SIZE,
 779                                                 s->tmp_hash);
 780                         if (rc) {
 781                                 printk(KERN_ERR
 782                                        "%s: Error computing crypto hash; "
 783                                        "rc = [%d]\n", __func__, rc);
 784                                 goto out_release_free_unlock;
 785                         }
 786                         memcpy(s->hash, s->tmp_hash,
 787                                ECRYPTFS_TAG_70_DIGEST_SIZE);
 788                 }
 789                 if (s->block_aligned_filename[s->j] == '\0')
 790                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
 791         }
 792         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 793                filename_size);
 794         rc = virt_to_scatterlist(s->block_aligned_filename,
 795                                  s->block_aligned_filename_size, s->src_sg, 2);
 796         if (rc < 1) {
 797                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 798                        "convert filename memory to scatterlist; rc = [%d]. "
 799                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 800                        s->block_aligned_filename_size);
 801                 goto out_release_free_unlock;
 802         }
 803         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
 804                                  s->dst_sg, 2);
 805         if (rc < 1) {
 806                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 807                        "convert encrypted filename memory to scatterlist; "
 808                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 809                        __func__, rc, s->block_aligned_filename_size);
 810                 goto out_release_free_unlock;
 811         }
 812         /* The characters in the first block effectively do the job
 813          * of the IV here, so we just use 0's for the IV. Note the
 814          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
 815          * >= ECRYPTFS_MAX_IV_BYTES. */
 816         rc = crypto_skcipher_setkey(
 817                 s->skcipher_tfm,
 818                 s->auth_tok->token.password.session_key_encryption_key,
 819                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 820         if (rc < 0) {
 821                 printk(KERN_ERR "%s: Error setting key for crypto context; "
 822                        "rc = [%d]. s->auth_tok->token.password.session_key_"
 823                        "encryption_key = [0x%p]; mount_crypt_stat->"
 824                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
 825                        rc,
 826                        s->auth_tok->token.password.session_key_encryption_key,
 827                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 828                 goto out_release_free_unlock;
 829         }
 830         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
 831                                    s->block_aligned_filename_size, s->iv);
 832         rc = crypto_skcipher_encrypt(s->skcipher_req);
 833         if (rc) {
 834                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
 835                        "rc = [%d]\n", __func__, rc);
 836                 goto out_release_free_unlock;
 837         }
 838         s->i += s->block_aligned_filename_size;
 839         (*packet_size) = s->i;
 840         (*remaining_bytes) -= (*packet_size);
 841 out_release_free_unlock:
 842         crypto_free_shash(s->hash_tfm);
 843 out_free_unlock:
 844         kfree_sensitive(s->block_aligned_filename);
 845 out_unlock:
 846         mutex_unlock(s->tfm_mutex);
 847 out:
 848         if (auth_tok_key) {
 849                 up_write(&(auth_tok_key->sem));
 850                 key_put(auth_tok_key);
 851         }
 852         skcipher_request_free(s->skcipher_req);
 853         kfree_sensitive(s->hash_desc);
 854         kfree(s);
 855         return rc;
 856 }
 857
 858 struct ecryptfs_parse_tag_70_packet_silly_stack {
 859         u8 cipher_code;
 860         size_t max_packet_size;
 861         size_t packet_size_len;
 862         size_t parsed_tag_70_packet_size;
 863         size_t block_aligned_filename_size;
 864         size_t block_size;
 865         size_t i;
 866         struct mutex *tfm_mutex;
 867         char *decrypted_filename;
 868         struct ecryptfs_auth_tok *auth_tok;
 869         struct scatterlist src_sg[2];
 870         struct scatterlist dst_sg[2];
 871         struct crypto_skcipher *skcipher_tfm;
 872         struct skcipher_request *skcipher_req;
 873         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 874         char iv[ECRYPTFS_MAX_IV_BYTES];
 875         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
 876 };
 877
 878 /**
 879  * ecryptfs_parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 880  * @filename: This function kmalloc's the memory for the filename
 881  * @filename_size: This function sets this to the amount of memory
 882  *                 kmalloc'd for the filename
 883  * @packet_size: This function sets this to the the number of octets
 884  *               in the packet parsed
 885  * @mount_crypt_stat: The mount-wide cryptographic context
 886  * @data: The memory location containing the start of the tag 70
 887  *        packet
 888  * @max_packet_size: The maximum legal size of the packet to be parsed
 889  *                   from @data
 890  *
 891  * Returns zero on success; non-zero otherwise
 892  */
 893 int
 894 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 895                              size_t *packet_size,
 896                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 897                              char *data, size_t max_packet_size)
 898 {
 899         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
 900         struct key *auth_tok_key = NULL;
 901         int rc = 0;
 902
 903         (*packet_size) = 0;
 904         (*filename_size) = 0;
 905         (*filename) = NULL;
 906         s = kzalloc(sizeof(*s), GFP_KERNEL);
 907         if (!s)
 908                 return -ENOMEM;
 909
 910         if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
 911                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
 912                        "at least [%d]\n", __func__, max_packet_size,
 913                        ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
 914                 rc = -EINVAL;
 915                 goto out;
 916         }
 917         /* Octet 0: Tag 70 identifier
 918          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 919          *              and block-aligned encrypted filename size)
 920          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 921          * Octet N2-N3: Cipher identifier (1 octet)
 922          * Octets N3-N4: Block-aligned encrypted filename
 923          *  - Consists of a minimum number of random numbers, a \0
 924          *    separator, and then the filename */
 925         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
 926                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
 927                        "tag [0x%.2x]\n", __func__,
 928                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
 929                 rc = -EINVAL;
 930                 goto out;
 931         }
 932         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
 933                                           &s->parsed_tag_70_packet_size,
 934                                           &s->packet_size_len);
 935         if (rc) {
 936                 printk(KERN_WARNING "%s: Error parsing packet length; "
 937                        "rc = [%d]\n", __func__, rc);
 938                 goto out;
 939         }
 940         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
 941                                           - ECRYPTFS_SIG_SIZE - 1);
 942         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
 943             > max_packet_size) {
 944                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
 945                        "size is [%zd]\n", __func__, max_packet_size,
 946                        (1 + s->packet_size_len + 1
 947                         + s->block_aligned_filename_size));
 948                 rc = -EINVAL;
 949                 goto out;
 950         }
 951         (*packet_size) += s->packet_size_len;
 952         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
 953                         ECRYPTFS_SIG_SIZE);
 954         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 955         (*packet_size) += ECRYPTFS_SIG_SIZE;
 956         s->cipher_code = data[(*packet_size)++];
 957         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
 958         if (rc) {
 959                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
 960                        __func__, s->cipher_code);
 961                 goto out;
 962         }
 963         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
 964                                             &s->auth_tok, mount_crypt_stat,
 965                                             s->fnek_sig_hex);
 966         if (rc) {
 967                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 968                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
 969                        rc);
 970                 goto out;
 971         }
 972         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
 973                                                         &s->tfm_mutex,
 974                                                         s->cipher_string);
 975         if (unlikely(rc)) {
 976                 printk(KERN_ERR "Internal error whilst attempting to get "
 977                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 978                        s->cipher_string, rc);
 979                 goto out;
 980         }
 981         mutex_lock(s->tfm_mutex);
 982         rc = virt_to_scatterlist(&data[(*packet_size)],
 983                                  s->block_aligned_filename_size, s->src_sg, 2);
 984         if (rc < 1) {
 985                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 986                        "convert encrypted filename memory to scatterlist; "
 987                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 988                        __func__, rc, s->block_aligned_filename_size);
 989                 goto out_unlock;
 990         }
 991         (*packet_size) += s->block_aligned_filename_size;
 992         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
 993                                         GFP_KERNEL);
 994         if (!s->decrypted_filename) {
 995                 rc = -ENOMEM;
 996                 goto out_unlock;
 997         }
 998         rc = virt_to_scatterlist(s->decrypted_filename,
 999                                  s->block_aligned_filename_size, s->dst_sg, 2);
1000         if (rc < 1) {
1001                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1002                        "convert decrypted filename memory to scatterlist; "
1003                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1004                        __func__, rc, s->block_aligned_filename_size);
1005                 goto out_free_unlock;
1006         }
1007
1008         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
1009         if (!s->skcipher_req) {
1010                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1011                        "skcipher_request_alloc for %s\n", __func__,
1012                        crypto_skcipher_driver_name(s->skcipher_tfm));
1013                 rc = -ENOMEM;
1014                 goto out_free_unlock;
1015         }
1016
1017         skcipher_request_set_callback(s->skcipher_req,
1018                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
1019
1020         /* The characters in the first block effectively do the job of
1021          * the IV here, so we just use 0's for the IV. Note the
1022          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1023          * >= ECRYPTFS_MAX_IV_BYTES. */
1024         /* TODO: Support other key modules than passphrase for
1025          * filename encryption */
1026         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1027                 rc = -EOPNOTSUPP;
1028                 printk(KERN_INFO "%s: Filename encryption only supports "
1029                        "password tokens\n", __func__);
1030                 goto out_free_unlock;
1031         }
1032         rc = crypto_skcipher_setkey(
1033                 s->skcipher_tfm,
1034                 s->auth_tok->token.password.session_key_encryption_key,
1035                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1036         if (rc < 0) {
1037                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1038                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1039                        "encryption_key = [0x%p]; mount_crypt_stat->"
1040                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1041                        rc,
1042                        s->auth_tok->token.password.session_key_encryption_key,
1043                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1044                 goto out_free_unlock;
1045         }
1046         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
1047                                    s->block_aligned_filename_size, s->iv);
1048         rc = crypto_skcipher_decrypt(s->skcipher_req);
1049         if (rc) {
1050                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1051                        "rc = [%d]\n", __func__, rc);
1052                 goto out_free_unlock;
1053         }
1054
1055         while (s->i < s->block_aligned_filename_size &&
1056                s->decrypted_filename[s->i] != '\0')
1057                 s->i++;
1058         if (s->i == s->block_aligned_filename_size) {
1059                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1060                        "find valid separator between random characters and "
1061                        "the filename\n", __func__);
1062                 rc = -EINVAL;
1063                 goto out_free_unlock;
1064         }
1065         s->i++;
1066         (*filename_size) = (s->block_aligned_filename_size - s->i);
1067         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1068                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1069                        "invalid\n", __func__, (*filename_size));
1070                 rc = -EINVAL;
1071                 goto out_free_unlock;
1072         }
1073         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1074         if (!(*filename)) {
1075                 rc = -ENOMEM;
1076                 goto out_free_unlock;
1077         }
1078         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1079         (*filename)[(*filename_size)] = '\0';
1080 out_free_unlock:
1081         kfree(s->decrypted_filename);
1082 out_unlock:
1083         mutex_unlock(s->tfm_mutex);
1084 out:
1085         if (rc) {
1086                 (*packet_size) = 0;
1087                 (*filename_size) = 0;
1088                 (*filename) = NULL;
1089         }
1090         if (auth_tok_key) {
1091                 up_write(&(auth_tok_key->sem));
1092                 key_put(auth_tok_key);
1093         }
1094         skcipher_request_free(s->skcipher_req);
1095         kfree(s);
1096         return rc;
1097 }
1098
1099 static int
1100 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1101 {
1102         int rc = 0;
1103
1104         (*sig) = NULL;
1105         switch (auth_tok->token_type) {
1106         case ECRYPTFS_PASSWORD:
1107                 (*sig) = auth_tok->token.password.signature;
1108                 break;
1109         case ECRYPTFS_PRIVATE_KEY:
1110                 (*sig) = auth_tok->token.private_key.signature;
1111                 break;
1112         default:
1113                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1114                        auth_tok->token_type);
1115                 rc = -EINVAL;
1116         }
1117         return rc;
1118 }
1119
1120 /**
1121  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1122  * @auth_tok: The key authentication token used to decrypt the session key
1123  * @crypt_stat: The cryptographic context
1124  *
1125  * Returns zero on success; non-zero error otherwise.
1126  */
1127 static int
1128 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1129                                   struct ecryptfs_crypt_stat *crypt_stat)
1130 {
1131         u8 cipher_code = 0;
1132         struct ecryptfs_msg_ctx *msg_ctx;
1133         struct ecryptfs_message *msg = NULL;
1134         char *auth_tok_sig;
1135         char *payload = NULL;
1136         size_t payload_len = 0;
1137         int rc;
1138
1139         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1140         if (rc) {
1141                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1142                        auth_tok->token_type);
1143                 goto out;
1144         }
1145         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1146                                  &payload, &payload_len);
1147         if (rc) {
1148                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1149                 goto out;
1150         }
1151         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1152         if (rc) {
1153                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1154                                 "ecryptfsd: %d\n", rc);
1155                 goto out;
1156         }
1157         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1158         if (rc) {
1159                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1160                                 "from the user space daemon\n");
1161                 rc = -EIO;
1162                 goto out;
1163         }
1164         rc = parse_tag_65_packet(&(auth_tok->session_key),
1165                                  &cipher_code, msg);
1166         if (rc) {
1167                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1168                        rc);
1169                 goto out;
1170         }
1171         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1172         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1173                auth_tok->session_key.decrypted_key_size);
1174         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1175         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1176         if (rc) {
1177                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1178                                 cipher_code);
1179                 goto out;
1180         }
1181         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1182         if (ecryptfs_verbosity > 0) {
1183                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1184                 ecryptfs_dump_hex(crypt_stat->key,
1185                                   crypt_stat->key_size);
1186         }
1187 out:
1188         kfree(msg);
1189         kfree(payload);
1190         return rc;
1191 }
1192
1193 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1194 {
1195         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1196         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1197
1198         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1199                                  auth_tok_list_head, list) {
1200                 list_del(&auth_tok_list_item->list);
1201                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1202                                 auth_tok_list_item);
1203         }
1204 }
1205
1206 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1207
1208 /**
1209  * parse_tag_1_packet
1210  * @crypt_stat: The cryptographic context to modify based on packet contents
1211  * @data: The raw bytes of the packet.
1212  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1213  *                 a new authentication token will be placed at the
1214  *                 end of this list for this packet.
1215  * @new_auth_tok: Pointer to a pointer to memory that this function
1216  *                allocates; sets the memory address of the pointer to
1217  *                NULL on error. This object is added to the
1218  *                auth_tok_list.
1219  * @packet_size: This function writes the size of the parsed packet
1220  *               into this memory location; zero on error.
1221  * @max_packet_size: The maximum allowable packet size
1222  *
1223  * Returns zero on success; non-zero on error.
1224  */
1225 static int
1226 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1227                    unsigned char *data, struct list_head *auth_tok_list,
1228                    struct ecryptfs_auth_tok **new_auth_tok,
1229                    size_t *packet_size, size_t max_packet_size)
1230 {
1231         size_t body_size;
1232         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1233         size_t length_size;
1234         int rc = 0;
1235
1236         (*packet_size) = 0;
1237         (*new_auth_tok) = NULL;
1238         /**
1239          * This format is inspired by OpenPGP; see RFC 2440
1240          * packet tag 1
1241          *
1242          * Tag 1 identifier (1 byte)
1243          * Max Tag 1 packet size (max 3 bytes)
1244          * Version (1 byte)
1245          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1246          * Cipher identifier (1 byte)
1247          * Encrypted key size (arbitrary)
1248          *
1249          * 12 bytes minimum packet size
1250          */
1251         if (unlikely(max_packet_size < 12)) {
1252                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1253                 rc = -EINVAL;
1254                 goto out;
1255         }
1256         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1257                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1258                        ECRYPTFS_TAG_1_PACKET_TYPE);
1259                 rc = -EINVAL;
1260                 goto out;
1261         }
1262         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1263          * at end of function upon failure */
1264         auth_tok_list_item =
1265                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1266                                   GFP_KERNEL);
1267         if (!auth_tok_list_item) {
1268                 printk(KERN_ERR "Unable to allocate memory\n");
1269                 rc = -ENOMEM;
1270                 goto out;
1271         }
1272         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1273         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1274                                           &length_size);
1275         if (rc) {
1276                 printk(KERN_WARNING "Error parsing packet length; "
1277                        "rc = [%d]\n", rc);
1278                 goto out_free;
1279         }
1280         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1281                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1282                 rc = -EINVAL;
1283                 goto out_free;
1284         }
1285         (*packet_size) += length_size;
1286         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1287                 printk(KERN_WARNING "Packet size exceeds max\n");
1288                 rc = -EINVAL;
1289                 goto out_free;
1290         }
1291         if (unlikely(data[(*packet_size)++] != 0x03)) {
1292                 printk(KERN_WARNING "Unknown version number [%d]\n",
1293                        data[(*packet_size) - 1]);
1294                 rc = -EINVAL;
1295                 goto out_free;
1296         }
1297         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1298                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1299         *packet_size += ECRYPTFS_SIG_SIZE;
1300         /* This byte is skipped because the kernel does not need to
1301          * know which public key encryption algorithm was used */
1302         (*packet_size)++;
1303         (*new_auth_tok)->session_key.encrypted_key_size =
1304                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1305         if ((*new_auth_tok)->session_key.encrypted_key_size
1306             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1307                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1308                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1309                 rc = -EINVAL;
1310                 goto out_free;
1311         }
1312         memcpy((*new_auth_tok)->session_key.encrypted_key,
1313                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1314         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1315         (*new_auth_tok)->session_key.flags &=
1316                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1317         (*new_auth_tok)->session_key.flags |=
1318                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1319         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1320         (*new_auth_tok)->flags = 0;
1321         (*new_auth_tok)->session_key.flags &=
1322                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1323         (*new_auth_tok)->session_key.flags &=
1324                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1325         list_add(&auth_tok_list_item->list, auth_tok_list);
1326         goto out;
1327 out_free:
1328         (*new_auth_tok) = NULL;
1329         memset(auth_tok_list_item, 0,
1330                sizeof(struct ecryptfs_auth_tok_list_item));
1331         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1332                         auth_tok_list_item);
1333 out:
1334         if (rc)
1335                 (*packet_size) = 0;
1336         return rc;
1337 }
1338
1339 /**
1340  * parse_tag_3_packet
1341  * @crypt_stat: The cryptographic context to modify based on packet
1342  *              contents.
1343  * @data: The raw bytes of the packet.
1344  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1345  *                 a new authentication token will be placed at the end
1346  *                 of this list for this packet.
1347  * @new_auth_tok: Pointer to a pointer to memory that this function
1348  *                allocates; sets the memory address of the pointer to
1349  *                NULL on error. This object is added to the
1350  *                auth_tok_list.
1351  * @packet_size: This function writes the size of the parsed packet
1352  *               into this memory location; zero on error.
1353  * @max_packet_size: maximum number of bytes to parse
1354  *
1355  * Returns zero on success; non-zero on error.
1356  */
1357 static int
1358 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1359                    unsigned char *data, struct list_head *auth_tok_list,
1360                    struct ecryptfs_auth_tok **new_auth_tok,
1361                    size_t *packet_size, size_t max_packet_size)
1362 {
1363         size_t body_size;
1364         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1365         size_t length_size;
1366         int rc = 0;
1367
1368         (*packet_size) = 0;
1369         (*new_auth_tok) = NULL;
1370         /**
1371          *This format is inspired by OpenPGP; see RFC 2440
1372          * packet tag 3
1373          *
1374          * Tag 3 identifier (1 byte)
1375          * Max Tag 3 packet size (max 3 bytes)
1376          * Version (1 byte)
1377          * Cipher code (1 byte)
1378          * S2K specifier (1 byte)
1379          * Hash identifier (1 byte)
1380          * Salt (ECRYPTFS_SALT_SIZE)
1381          * Hash iterations (1 byte)
1382          * Encrypted key (arbitrary)
1383          *
1384          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1385          */
1386         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1387                 printk(KERN_ERR "Max packet size too large\n");
1388                 rc = -EINVAL;
1389                 goto out;
1390         }
1391         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1392                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1393                        ECRYPTFS_TAG_3_PACKET_TYPE);
1394                 rc = -EINVAL;
1395                 goto out;
1396         }
1397         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1398          * at end of function upon failure */
1399         auth_tok_list_item =
1400             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1401         if (!auth_tok_list_item) {
1402                 printk(KERN_ERR "Unable to allocate memory\n");
1403                 rc = -ENOMEM;
1404                 goto out;
1405         }
1406         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1407         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1408                                           &length_size);
1409         if (rc) {
1410                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1411                        rc);
1412                 goto out_free;
1413         }
1414         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1415                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1416                 rc = -EINVAL;
1417                 goto out_free;
1418         }
1419         (*packet_size) += length_size;
1420         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1421                 printk(KERN_ERR "Packet size exceeds max\n");
1422                 rc = -EINVAL;
1423                 goto out_free;
1424         }
1425         (*new_auth_tok)->session_key.encrypted_key_size =
1426                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1427         if ((*new_auth_tok)->session_key.encrypted_key_size
1428             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1429                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1430                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1431                 rc = -EINVAL;
1432                 goto out_free;
1433         }
1434         if (unlikely(data[(*packet_size)++] != 0x04)) {
1435                 printk(KERN_WARNING "Unknown version number [%d]\n",
1436                        data[(*packet_size) - 1]);
1437                 rc = -EINVAL;
1438                 goto out_free;
1439         }
1440         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1441                                             (u16)data[(*packet_size)]);
1442         if (rc)
1443                 goto out_free;
1444         /* A little extra work to differentiate among the AES key
1445          * sizes; see RFC2440 */
1446         switch(data[(*packet_size)++]) {
1447         case RFC2440_CIPHER_AES_192:
1448                 crypt_stat->key_size = 24;
1449                 break;
1450         default:
1451                 crypt_stat->key_size =
1452                         (*new_auth_tok)->session_key.encrypted_key_size;
1453         }
1454         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1455         if (rc)
1456                 goto out_free;
1457         if (unlikely(data[(*packet_size)++] != 0x03)) {
1458                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1459                 rc = -ENOSYS;
1460                 goto out_free;
1461         }
1462         /* TODO: finish the hash mapping */
1463         switch (data[(*packet_size)++]) {
1464         case 0x01: /* See RFC2440 for these numbers and their mappings */
1465                 /* Choose MD5 */
1466                 memcpy((*new_auth_tok)->token.password.salt,
1467                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1468                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1469                 /* This conversion was taken straight from RFC2440 */
1470                 (*new_auth_tok)->token.password.hash_iterations =
1471                         ((u32) 16 + (data[(*packet_size)] & 15))
1472                                 << ((data[(*packet_size)] >> 4) + 6);
1473                 (*packet_size)++;
1474                 /* Friendly reminder:
1475                  * (*new_auth_tok)->session_key.encrypted_key_size =
1476                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1477                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1478                        &data[(*packet_size)],
1479                        (*new_auth_tok)->session_key.encrypted_key_size);
1480                 (*packet_size) +=
1481                         (*new_auth_tok)->session_key.encrypted_key_size;
1482                 (*new_auth_tok)->session_key.flags &=
1483                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1484                 (*new_auth_tok)->session_key.flags |=
1485                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1486                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1487                 break;
1488         default:
1489                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1490                                 "[%d]\n", data[(*packet_size) - 1]);
1491                 rc = -ENOSYS;
1492                 goto out_free;
1493         }
1494         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1495         /* TODO: Parametarize; we might actually want userspace to
1496          * decrypt the session key. */
1497         (*new_auth_tok)->session_key.flags &=
1498                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1499         (*new_auth_tok)->session_key.flags &=
1500                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1501         list_add(&auth_tok_list_item->list, auth_tok_list);
1502         goto out;
1503 out_free:
1504         (*new_auth_tok) = NULL;
1505         memset(auth_tok_list_item, 0,
1506                sizeof(struct ecryptfs_auth_tok_list_item));
1507         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1508                         auth_tok_list_item);
1509 out:
1510         if (rc)
1511                 (*packet_size) = 0;
1512         return rc;
1513 }
1514
1515 /**
1516  * parse_tag_11_packet
1517  * @data: The raw bytes of the packet
1518  * @contents: This function writes the data contents of the literal
1519  *            packet into this memory location
1520  * @max_contents_bytes: The maximum number of bytes that this function
1521  *                      is allowed to write into contents
1522  * @tag_11_contents_size: This function writes the size of the parsed
1523  *                        contents into this memory location; zero on
1524  *                        error
1525  * @packet_size: This function writes the size of the parsed packet
1526  *               into this memory location; zero on error
1527  * @max_packet_size: maximum number of bytes to parse
1528  *
1529  * Returns zero on success; non-zero on error.
1530  */
1531 static int
1532 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1533                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1534                     size_t *packet_size, size_t max_packet_size)
1535 {
1536         size_t body_size;
1537         size_t length_size;
1538         int rc = 0;
1539
1540         (*packet_size) = 0;
1541         (*tag_11_contents_size) = 0;
1542         /* This format is inspired by OpenPGP; see RFC 2440
1543          * packet tag 11
1544          *
1545          * Tag 11 identifier (1 byte)
1546          * Max Tag 11 packet size (max 3 bytes)
1547          * Binary format specifier (1 byte)
1548          * Filename length (1 byte)
1549          * Filename ("_CONSOLE") (8 bytes)
1550          * Modification date (4 bytes)
1551          * Literal data (arbitrary)
1552          *
1553          * We need at least 16 bytes of data for the packet to even be
1554          * valid.
1555          */
1556         if (max_packet_size < 16) {
1557                 printk(KERN_ERR "Maximum packet size too small\n");
1558                 rc = -EINVAL;
1559                 goto out;
1560         }
1561         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1562                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1563                 rc = -EINVAL;
1564                 goto out;
1565         }
1566         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1567                                           &length_size);
1568         if (rc) {
1569                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1570                 goto out;
1571         }
1572         if (body_size < 14) {
1573                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1574                 rc = -EINVAL;
1575                 goto out;
1576         }
1577         (*packet_size) += length_size;
1578         (*tag_11_contents_size) = (body_size - 14);
1579         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1580                 printk(KERN_ERR "Packet size exceeds max\n");
1581                 rc = -EINVAL;
1582                 goto out;
1583         }
1584         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1585                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1586                        "expected size\n");
1587                 rc = -EINVAL;
1588                 goto out;
1589         }
1590         if (data[(*packet_size)++] != 0x62) {
1591                 printk(KERN_WARNING "Unrecognizable packet\n");
1592                 rc = -EINVAL;
1593                 goto out;
1594         }
1595         if (data[(*packet_size)++] != 0x08) {
1596                 printk(KERN_WARNING "Unrecognizable packet\n");
1597                 rc = -EINVAL;
1598                 goto out;
1599         }
1600         (*packet_size) += 12; /* Ignore filename and modification date */
1601         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1602         (*packet_size) += (*tag_11_contents_size);
1603 out:
1604         if (rc) {
1605                 (*packet_size) = 0;
1606                 (*tag_11_contents_size) = 0;
1607         }
1608         return rc;
1609 }
1610
1611 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1612                                       struct ecryptfs_auth_tok **auth_tok,
1613                                       char *sig)
1614 {
1615         int rc = 0;
1616
1617         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1618         if (IS_ERR(*auth_tok_key)) {
1619                 (*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1620                 if (IS_ERR(*auth_tok_key)) {
1621                         printk(KERN_ERR "Could not find key with description: [%s]\n",
1622                               sig);
1623                         rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1624                         (*auth_tok_key) = NULL;
1625                         goto out;
1626                 }
1627         }
1628         down_write(&(*auth_tok_key)->sem);
1629         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1630         if (rc) {
1631                 up_write(&(*auth_tok_key)->sem);
1632                 key_put(*auth_tok_key);
1633                 (*auth_tok_key) = NULL;
1634                 goto out;
1635         }
1636 out:
1637         return rc;
1638 }
1639
1640 /**
1641  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1642  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1643  * @crypt_stat: The cryptographic context
1644  *
1645  * Returns zero on success; non-zero error otherwise
1646  */
1647 static int
1648 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1649                                          struct ecryptfs_crypt_stat *crypt_stat)
1650 {
1651         struct scatterlist dst_sg[2];
1652         struct scatterlist src_sg[2];
1653         struct mutex *tfm_mutex;
1654         struct crypto_skcipher *tfm;
1655         struct skcipher_request *req = NULL;
1656         int rc = 0;
1657
1658         if (unlikely(ecryptfs_verbosity > 0)) {
1659                 ecryptfs_printk(
1660                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1661                         auth_tok->token.password.session_key_encryption_key_bytes);
1662                 ecryptfs_dump_hex(
1663                         auth_tok->token.password.session_key_encryption_key,
1664                         auth_tok->token.password.session_key_encryption_key_bytes);
1665         }
1666         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
1667                                                         crypt_stat->cipher);
1668         if (unlikely(rc)) {
1669                 printk(KERN_ERR "Internal error whilst attempting to get "
1670                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1671                        crypt_stat->cipher, rc);
1672                 goto out;
1673         }
1674         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1675                                  auth_tok->session_key.encrypted_key_size,
1676                                  src_sg, 2);
1677         if (rc < 1 || rc > 2) {
1678                 printk(KERN_ERR "Internal error whilst attempting to convert "
1679                         "auth_tok->session_key.encrypted_key to scatterlist; "
1680                         "expected rc = 1; got rc = [%d]. "
1681                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1682                         auth_tok->session_key.encrypted_key_size);
1683                 goto out;
1684         }
1685         auth_tok->session_key.decrypted_key_size =
1686                 auth_tok->session_key.encrypted_key_size;
1687         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1688                                  auth_tok->session_key.decrypted_key_size,
1689                                  dst_sg, 2);
1690         if (rc < 1 || rc > 2) {
1691                 printk(KERN_ERR "Internal error whilst attempting to convert "
1692                         "auth_tok->session_key.decrypted_key to scatterlist; "
1693                         "expected rc = 1; got rc = [%d]\n", rc);
1694                 goto out;
1695         }
1696         mutex_lock(tfm_mutex);
1697         req = skcipher_request_alloc(tfm, GFP_KERNEL);
1698         if (!req) {
1699                 mutex_unlock(tfm_mutex);
1700                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1701                        "skcipher_request_alloc for %s\n", __func__,
1702                        crypto_skcipher_driver_name(tfm));
1703                 rc = -ENOMEM;
1704                 goto out;
1705         }
1706
1707         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
1708                                       NULL, NULL);
1709         rc = crypto_skcipher_setkey(
1710                 tfm, auth_tok->token.password.session_key_encryption_key,
1711                 crypt_stat->key_size);
1712         if (unlikely(rc < 0)) {
1713                 mutex_unlock(tfm_mutex);
1714                 printk(KERN_ERR "Error setting key for crypto context\n");
1715                 rc = -EINVAL;
1716                 goto out;
1717         }
1718         skcipher_request_set_crypt(req, src_sg, dst_sg,
1719                                    auth_tok->session_key.encrypted_key_size,
1720                                    NULL);
1721         rc = crypto_skcipher_decrypt(req);
1722         mutex_unlock(tfm_mutex);
1723         if (unlikely(rc)) {
1724                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1725                 goto out;
1726         }
1727         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1728         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1729                auth_tok->session_key.decrypted_key_size);
1730         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1731         if (unlikely(ecryptfs_verbosity > 0)) {
1732                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1733                                 crypt_stat->key_size);
1734                 ecryptfs_dump_hex(crypt_stat->key,
1735                                   crypt_stat->key_size);
1736         }
1737 out:
1738         skcipher_request_free(req);
1739         return rc;
1740 }
1741
1742 /**
1743  * ecryptfs_parse_packet_set
1744  * @crypt_stat: The cryptographic context
1745  * @src: Virtual address of region of memory containing the packets
1746  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1747  *
1748  * Get crypt_stat to have the file's session key if the requisite key
1749  * is available to decrypt the session key.
1750  *
1751  * Returns Zero if a valid authentication token was retrieved and
1752  * processed; negative value for file not encrypted or for error
1753  * conditions.
1754  */
1755 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1756                               unsigned char *src,
1757                               struct dentry *ecryptfs_dentry)
1758 {
1759         size_t i = 0;
1760         size_t found_auth_tok;
1761         size_t next_packet_is_auth_tok_packet;
1762         struct list_head auth_tok_list;
1763         struct ecryptfs_auth_tok *matching_auth_tok;
1764         struct ecryptfs_auth_tok *candidate_auth_tok;
1765         char *candidate_auth_tok_sig;
1766         size_t packet_size;
1767         struct ecryptfs_auth_tok *new_auth_tok;
1768         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1769         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1770         size_t tag_11_contents_size;
1771         size_t tag_11_packet_size;
1772         struct key *auth_tok_key = NULL;
1773         int rc = 0;
1774
1775         INIT_LIST_HEAD(&auth_tok_list);
1776         /* Parse the header to find as many packets as we can; these will be
1777          * added the our &auth_tok_list */
1778         next_packet_is_auth_tok_packet = 1;
1779         while (next_packet_is_auth_tok_packet) {
1780                 size_t max_packet_size = ((PAGE_SIZE - 8) - i);
1781
1782                 switch (src[i]) {
1783                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1784                         rc = parse_tag_3_packet(crypt_stat,
1785                                                 (unsigned char *)&src[i],
1786                                                 &auth_tok_list, &new_auth_tok,
1787                                                 &packet_size, max_packet_size);
1788                         if (rc) {
1789                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1790                                                 "tag 3 packet\n");
1791                                 rc = -EIO;
1792                                 goto out_wipe_list;
1793                         }
1794                         i += packet_size;
1795                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1796                                                  sig_tmp_space,
1797                                                  ECRYPTFS_SIG_SIZE,
1798                                                  &tag_11_contents_size,
1799                                                  &tag_11_packet_size,
1800                                                  max_packet_size);
1801                         if (rc) {
1802                                 ecryptfs_printk(KERN_ERR, "No valid "
1803                                                 "(ecryptfs-specific) literal "
1804                                                 "packet containing "
1805                                                 "authentication token "
1806                                                 "signature found after "
1807                                                 "tag 3 packet\n");
1808                                 rc = -EIO;
1809                                 goto out_wipe_list;
1810                         }
1811                         i += tag_11_packet_size;
1812                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1813                                 ecryptfs_printk(KERN_ERR, "Expected "
1814                                                 "signature of size [%d]; "
1815                                                 "read size [%zd]\n",
1816                                                 ECRYPTFS_SIG_SIZE,
1817                                                 tag_11_contents_size);
1818                                 rc = -EIO;
1819                                 goto out_wipe_list;
1820                         }
1821                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1822                                         sig_tmp_space, tag_11_contents_size);
1823                         new_auth_tok->token.password.signature[
1824                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1825                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1826                         break;
1827                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1828                         rc = parse_tag_1_packet(crypt_stat,
1829                                                 (unsigned char *)&src[i],
1830                                                 &auth_tok_list, &new_auth_tok,
1831                                                 &packet_size, max_packet_size);
1832                         if (rc) {
1833                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1834                                                 "tag 1 packet\n");
1835                                 rc = -EIO;
1836                                 goto out_wipe_list;
1837                         }
1838                         i += packet_size;
1839                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1840                         break;
1841                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1842                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1843                                         "(Tag 11 not allowed by itself)\n");
1844                         rc = -EIO;
1845                         goto out_wipe_list;
1846                 default:
1847                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1848                                         "of the file header; hex value of "
1849                                         "character is [0x%.2x]\n", i, src[i]);
1850                         next_packet_is_auth_tok_packet = 0;
1851                 }
1852         }
1853         if (list_empty(&auth_tok_list)) {
1854                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1855                        "eCryptfs file; this is not supported in this version "
1856                        "of the eCryptfs kernel module\n");
1857                 rc = -EINVAL;
1858                 goto out;
1859         }
1860         /* auth_tok_list contains the set of authentication tokens
1861          * parsed from the metadata. We need to find a matching
1862          * authentication token that has the secret component(s)
1863          * necessary to decrypt the EFEK in the auth_tok parsed from
1864          * the metadata. There may be several potential matches, but
1865          * just one will be sufficient to decrypt to get the FEK. */
1866 find_next_matching_auth_tok:
1867         found_auth_tok = 0;
1868         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1869                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1870                 if (unlikely(ecryptfs_verbosity > 0)) {
1871                         ecryptfs_printk(KERN_DEBUG,
1872                                         "Considering candidate auth tok:\n");
1873                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1874                 }
1875                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1876                                                candidate_auth_tok);
1877                 if (rc) {
1878                         printk(KERN_ERR
1879                                "Unrecognized candidate auth tok type: [%d]\n",
1880                                candidate_auth_tok->token_type);
1881                         rc = -EINVAL;
1882                         goto out_wipe_list;
1883                 }
1884                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1885                                                &matching_auth_tok,
1886                                                crypt_stat->mount_crypt_stat,
1887                                                candidate_auth_tok_sig);
1888                 if (!rc) {
1889                         found_auth_tok = 1;
1890                         goto found_matching_auth_tok;
1891                 }
1892         }
1893         if (!found_auth_tok) {
1894                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1895                                 "authentication token\n");
1896                 rc = -EIO;
1897                 goto out_wipe_list;
1898         }
1899 found_matching_auth_tok:
1900         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1901                 memcpy(&(candidate_auth_tok->token.private_key),
1902                        &(matching_auth_tok->token.private_key),
1903                        sizeof(struct ecryptfs_private_key));
1904                 up_write(&(auth_tok_key->sem));
1905                 key_put(auth_tok_key);
1906                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1907                                                        crypt_stat);
1908         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1909                 memcpy(&(candidate_auth_tok->token.password),
1910                        &(matching_auth_tok->token.password),
1911                        sizeof(struct ecryptfs_password));
1912                 up_write(&(auth_tok_key->sem));
1913                 key_put(auth_tok_key);
1914                 rc = decrypt_passphrase_encrypted_session_key(
1915                         candidate_auth_tok, crypt_stat);
1916         } else {
1917                 up_write(&(auth_tok_key->sem));
1918                 key_put(auth_tok_key);
1919                 rc = -EINVAL;
1920         }
1921         if (rc) {
1922                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1923
1924                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1925                                 "session key for authentication token with sig "
1926                                 "[%.*s]; rc = [%d]. Removing auth tok "
1927                                 "candidate from the list and searching for "
1928                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1929                                 candidate_auth_tok_sig, rc);
1930                 list_for_each_entry_safe(auth_tok_list_item,
1931                                          auth_tok_list_item_tmp,
1932                                          &auth_tok_list, list) {
1933                         if (candidate_auth_tok
1934                             == &auth_tok_list_item->auth_tok) {
1935                                 list_del(&auth_tok_list_item->list);
1936                                 kmem_cache_free(
1937                                         ecryptfs_auth_tok_list_item_cache,
1938                                         auth_tok_list_item);
1939                                 goto find_next_matching_auth_tok;
1940                         }
1941                 }
1942                 BUG();
1943         }
1944         rc = ecryptfs_compute_root_iv(crypt_stat);
1945         if (rc) {
1946                 ecryptfs_printk(KERN_ERR, "Error computing "
1947                                 "the root IV\n");
1948                 goto out_wipe_list;
1949         }
1950         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1951         if (rc) {
1952                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1953                                 "context for cipher [%s]; rc = [%d]\n",
1954                                 crypt_stat->cipher, rc);
1955         }
1956 out_wipe_list:
1957         wipe_auth_tok_list(&auth_tok_list);
1958 out:
1959         return rc;
1960 }
1961
1962 static int
1963 pki_encrypt_session_key(struct key *auth_tok_key,
1964                         struct ecryptfs_auth_tok *auth_tok,
1965                         struct ecryptfs_crypt_stat *crypt_stat,
1966                         struct ecryptfs_key_record *key_rec)
1967 {
1968         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1969         char *payload = NULL;
1970         size_t payload_len = 0;
1971         struct ecryptfs_message *msg;
1972         int rc;
1973
1974         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1975                                  ecryptfs_code_for_cipher_string(
1976                                          crypt_stat->cipher,
1977                                          crypt_stat->key_size),
1978                                  crypt_stat, &payload, &payload_len);
1979         up_write(&(auth_tok_key->sem));
1980         key_put(auth_tok_key);
1981         if (rc) {
1982                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1983                 goto out;
1984         }
1985         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1986         if (rc) {
1987                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1988                                 "ecryptfsd: %d\n", rc);
1989                 goto out;
1990         }
1991         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1992         if (rc) {
1993                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1994                                 "from the user space daemon\n");
1995                 rc = -EIO;
1996                 goto out;
1997         }
1998         rc = parse_tag_67_packet(key_rec, msg);
1999         if (rc)
2000                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
2001         kfree(msg);
2002 out:
2003         kfree(payload);
2004         return rc;
2005 }
2006 /**
2007  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2008  * @dest: Buffer into which to write the packet
2009  * @remaining_bytes: Maximum number of bytes that can be writtn
2010  * @auth_tok_key: The authentication token key to unlock and put when done with
2011  *                @auth_tok
2012  * @auth_tok: The authentication token used for generating the tag 1 packet
2013  * @crypt_stat: The cryptographic context
2014  * @key_rec: The key record struct for the tag 1 packet
2015  * @packet_size: This function will write the number of bytes that end
2016  *               up constituting the packet; set to zero on error
2017  *
2018  * Returns zero on success; non-zero on error.
2019  */
2020 static int
2021 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2022                    struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2023                    struct ecryptfs_crypt_stat *crypt_stat,
2024                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2025 {
2026         size_t i;
2027         size_t encrypted_session_key_valid = 0;
2028         size_t packet_size_length;
2029         size_t max_packet_size;
2030         int rc = 0;
2031
2032         (*packet_size) = 0;
2033         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2034                           ECRYPTFS_SIG_SIZE);
2035         encrypted_session_key_valid = 0;
2036         for (i = 0; i < crypt_stat->key_size; i++)
2037                 encrypted_session_key_valid |=
2038                         auth_tok->session_key.encrypted_key[i];
2039         if (encrypted_session_key_valid) {
2040                 memcpy(key_rec->enc_key,
2041                        auth_tok->session_key.encrypted_key,
2042                        auth_tok->session_key.encrypted_key_size);
2043                 up_write(&(auth_tok_key->sem));
2044                 key_put(auth_tok_key);
2045                 goto encrypted_session_key_set;
2046         }
2047         if (auth_tok->session_key.encrypted_key_size == 0)
2048                 auth_tok->session_key.encrypted_key_size =
2049                         auth_tok->token.private_key.key_size;
2050         rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2051                                      key_rec);
2052         if (rc) {
2053                 printk(KERN_ERR "Failed to encrypt session key via a key "
2054                        "module; rc = [%d]\n", rc);
2055                 goto out;
2056         }
2057         if (ecryptfs_verbosity > 0) {
2058                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2059                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2060         }
2061 encrypted_session_key_set:
2062         /* This format is inspired by OpenPGP; see RFC 2440
2063          * packet tag 1 */
2064         max_packet_size = (1                         /* Tag 1 identifier */
2065                            + 3                       /* Max Tag 1 packet size */
2066                            + 1                       /* Version */
2067                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2068                            + 1                       /* Cipher identifier */
2069                            + key_rec->enc_key_size); /* Encrypted key size */
2070         if (max_packet_size > (*remaining_bytes)) {
2071                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2072                        "need up to [%td] bytes, but there are only [%td] "
2073                        "available\n", max_packet_size, (*remaining_bytes));
2074                 rc = -EINVAL;
2075                 goto out;
2076         }
2077         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2078         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2079                                           (max_packet_size - 4),
2080                                           &packet_size_length);
2081         if (rc) {
2082                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2083                                 "header; cannot generate packet length\n");
2084                 goto out;
2085         }
2086         (*packet_size) += packet_size_length;
2087         dest[(*packet_size)++] = 0x03; /* version 3 */
2088         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2089         (*packet_size) += ECRYPTFS_SIG_SIZE;
2090         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2091         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2092                key_rec->enc_key_size);
2093         (*packet_size) += key_rec->enc_key_size;
2094 out:
2095         if (rc)
2096                 (*packet_size) = 0;
2097         else
2098                 (*remaining_bytes) -= (*packet_size);
2099         return rc;
2100 }
2101
2102 /**
2103  * write_tag_11_packet
2104  * @dest: Target into which Tag 11 packet is to be written
2105  * @remaining_bytes: Maximum packet length
2106  * @contents: Byte array of contents to copy in
2107  * @contents_length: Number of bytes in contents
2108  * @packet_length: Length of the Tag 11 packet written; zero on error
2109  *
2110  * Returns zero on success; non-zero on error.
2111  */
2112 static int
2113 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2114                     size_t contents_length, size_t *packet_length)
2115 {
2116         size_t packet_size_length;
2117         size_t max_packet_size;
2118         int rc = 0;
2119
2120         (*packet_length) = 0;
2121         /* This format is inspired by OpenPGP; see RFC 2440
2122          * packet tag 11 */
2123         max_packet_size = (1                   /* Tag 11 identifier */
2124                            + 3                 /* Max Tag 11 packet size */
2125                            + 1                 /* Binary format specifier */
2126                            + 1                 /* Filename length */
2127                            + 8                 /* Filename ("_CONSOLE") */
2128                            + 4                 /* Modification date */
2129                            + contents_length); /* Literal data */
2130         if (max_packet_size > (*remaining_bytes)) {
2131                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2132                        "need up to [%td] bytes, but there are only [%td] "
2133                        "available\n", max_packet_size, (*remaining_bytes));
2134                 rc = -EINVAL;
2135                 goto out;
2136         }
2137         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2138         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2139                                           (max_packet_size - 4),
2140                                           &packet_size_length);
2141         if (rc) {
2142                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2143                        "generate packet length. rc = [%d]\n", rc);
2144                 goto out;
2145         }
2146         (*packet_length) += packet_size_length;
2147         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2148         dest[(*packet_length)++] = 8;
2149         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2150         (*packet_length) += 8;
2151         memset(&dest[(*packet_length)], 0x00, 4);
2152         (*packet_length) += 4;
2153         memcpy(&dest[(*packet_length)], contents, contents_length);
2154         (*packet_length) += contents_length;
2155  out:
2156         if (rc)
2157                 (*packet_length) = 0;
2158         else
2159                 (*remaining_bytes) -= (*packet_length);
2160         return rc;
2161 }
2162
2163 /**
2164  * write_tag_3_packet
2165  * @dest: Buffer into which to write the packet
2166  * @remaining_bytes: Maximum number of bytes that can be written
2167  * @auth_tok: Authentication token
2168  * @crypt_stat: The cryptographic context
2169  * @key_rec: encrypted key
2170  * @packet_size: This function will write the number of bytes that end
2171  *               up constituting the packet; set to zero on error
2172  *
2173  * Returns zero on success; non-zero on error.
2174  */
2175 static int
2176 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2177                    struct ecryptfs_auth_tok *auth_tok,
2178                    struct ecryptfs_crypt_stat *crypt_stat,
2179                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2180 {
2181         size_t i;
2182         size_t encrypted_session_key_valid = 0;
2183         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2184         struct scatterlist dst_sg[2];
2185         struct scatterlist src_sg[2];
2186         struct mutex *tfm_mutex = NULL;
2187         u8 cipher_code;
2188         size_t packet_size_length;
2189         size_t max_packet_size;
2190         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2191                 crypt_stat->mount_crypt_stat;
2192         struct crypto_skcipher *tfm;
2193         struct skcipher_request *req;
2194         int rc = 0;
2195
2196         (*packet_size) = 0;
2197         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2198                           ECRYPTFS_SIG_SIZE);
2199         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2200                                                         crypt_stat->cipher);
2201         if (unlikely(rc)) {
2202                 printk(KERN_ERR "Internal error whilst attempting to get "
2203                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2204                        crypt_stat->cipher, rc);
2205                 goto out;
2206         }
2207         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2208                 printk(KERN_WARNING "No key size specified at mount; "
2209                        "defaulting to [%d]\n",
2210                        crypto_skcipher_max_keysize(tfm));
2211                 mount_crypt_stat->global_default_cipher_key_size =
2212                         crypto_skcipher_max_keysize(tfm);
2213         }
2214         if (crypt_stat->key_size == 0)
2215                 crypt_stat->key_size =
2216                         mount_crypt_stat->global_default_cipher_key_size;
2217         if (auth_tok->session_key.encrypted_key_size == 0)
2218                 auth_tok->session_key.encrypted_key_size =
2219                         crypt_stat->key_size;
2220         if (crypt_stat->key_size == 24
2221             && strcmp("aes", crypt_stat->cipher) == 0) {
2222                 memset((crypt_stat->key + 24), 0, 8);
2223                 auth_tok->session_key.encrypted_key_size = 32;
2224         } else
2225                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2226         key_rec->enc_key_size =
2227                 auth_tok->session_key.encrypted_key_size;
2228         encrypted_session_key_valid = 0;
2229         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2230                 encrypted_session_key_valid |=
2231                         auth_tok->session_key.encrypted_key[i];
2232         if (encrypted_session_key_valid) {
2233                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2234                                 "using auth_tok->session_key.encrypted_key, "
2235                                 "where key_rec->enc_key_size = [%zd]\n",
2236                                 key_rec->enc_key_size);
2237                 memcpy(key_rec->enc_key,
2238                        auth_tok->session_key.encrypted_key,
2239                        key_rec->enc_key_size);
2240                 goto encrypted_session_key_set;
2241         }
2242         if (auth_tok->token.password.flags &
2243             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2244                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2245                                 "session key encryption key of size [%d]\n",
2246                                 auth_tok->token.password.
2247                                 session_key_encryption_key_bytes);
2248                 memcpy(session_key_encryption_key,
2249                        auth_tok->token.password.session_key_encryption_key,
2250                        crypt_stat->key_size);
2251                 ecryptfs_printk(KERN_DEBUG,
2252                                 "Cached session key encryption key:\n");
2253                 if (ecryptfs_verbosity > 0)
2254                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2255         }
2256         if (unlikely(ecryptfs_verbosity > 0)) {
2257                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2258                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2259         }
2260         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2261                                  src_sg, 2);
2262         if (rc < 1 || rc > 2) {
2263                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2264                                 "for crypt_stat session key; expected rc = 1; "
2265                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2266                                 rc, key_rec->enc_key_size);
2267                 rc = -ENOMEM;
2268                 goto out;
2269         }
2270         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2271                                  dst_sg, 2);
2272         if (rc < 1 || rc > 2) {
2273                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2274                                 "for crypt_stat encrypted session key; "
2275                                 "expected rc = 1; got rc = [%d]. "
2276                                 "key_rec->enc_key_size = [%zd]\n", rc,
2277                                 key_rec->enc_key_size);
2278                 rc = -ENOMEM;
2279                 goto out;
2280         }
2281         mutex_lock(tfm_mutex);
2282         rc = crypto_skcipher_setkey(tfm, session_key_encryption_key,
2283                                     crypt_stat->key_size);
2284         if (rc < 0) {
2285                 mutex_unlock(tfm_mutex);
2286                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2287                                 "context; rc = [%d]\n", rc);
2288                 goto out;
2289         }
2290
2291         req = skcipher_request_alloc(tfm, GFP_KERNEL);
2292         if (!req) {
2293                 mutex_unlock(tfm_mutex);
2294                 ecryptfs_printk(KERN_ERR, "Out of kernel memory whilst "
2295                                 "attempting to skcipher_request_alloc for "
2296                                 "%s\n", crypto_skcipher_driver_name(tfm));
2297                 rc = -ENOMEM;
2298                 goto out;
2299         }
2300
2301         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
2302                                       NULL, NULL);
2303
2304         rc = 0;
2305         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2306                         crypt_stat->key_size);
2307         skcipher_request_set_crypt(req, src_sg, dst_sg,
2308                                    (*key_rec).enc_key_size, NULL);
2309         rc = crypto_skcipher_encrypt(req);
2310         mutex_unlock(tfm_mutex);
2311         skcipher_request_free(req);
2312         if (rc) {
2313                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2314                 goto out;
2315         }
2316         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2317         if (ecryptfs_verbosity > 0) {
2318                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2319                                 key_rec->enc_key_size);
2320                 ecryptfs_dump_hex(key_rec->enc_key,
2321                                   key_rec->enc_key_size);
2322         }
2323 encrypted_session_key_set:
2324         /* This format is inspired by OpenPGP; see RFC 2440
2325          * packet tag 3 */
2326         max_packet_size = (1                         /* Tag 3 identifier */
2327                            + 3                       /* Max Tag 3 packet size */
2328                            + 1                       /* Version */
2329                            + 1                       /* Cipher code */
2330                            + 1                       /* S2K specifier */
2331                            + 1                       /* Hash identifier */
2332                            + ECRYPTFS_SALT_SIZE      /* Salt */
2333                            + 1                       /* Hash iterations */
2334                            + key_rec->enc_key_size); /* Encrypted key size */
2335         if (max_packet_size > (*remaining_bytes)) {
2336                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2337                        "there are only [%td] available\n", max_packet_size,
2338                        (*remaining_bytes));
2339                 rc = -EINVAL;
2340                 goto out;
2341         }
2342         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2343         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2344          * to get the number of octets in the actual Tag 3 packet */
2345         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2346                                           (max_packet_size - 4),
2347                                           &packet_size_length);
2348         if (rc) {
2349                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2350                        "generate packet length. rc = [%d]\n", rc);
2351                 goto out;
2352         }
2353         (*packet_size) += packet_size_length;
2354         dest[(*packet_size)++] = 0x04; /* version 4 */
2355         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2356          * specified with strings */
2357         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2358                                                       crypt_stat->key_size);
2359         if (cipher_code == 0) {
2360                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2361                                 "cipher [%s]\n", crypt_stat->cipher);
2362                 rc = -EINVAL;
2363                 goto out;
2364         }
2365         dest[(*packet_size)++] = cipher_code;
2366         dest[(*packet_size)++] = 0x03;  /* S2K */
2367         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2368         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2369                ECRYPTFS_SALT_SIZE);
2370         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2371         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2372         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2373                key_rec->enc_key_size);
2374         (*packet_size) += key_rec->enc_key_size;
2375 out:
2376         if (rc)
2377                 (*packet_size) = 0;
2378         else
2379                 (*remaining_bytes) -= (*packet_size);
2380         return rc;
2381 }
2382
2383 struct kmem_cache *ecryptfs_key_record_cache;
2384
2385 /**
2386  * ecryptfs_generate_key_packet_set
2387  * @dest_base: Virtual address from which to write the key record set
2388  * @crypt_stat: The cryptographic context from which the
2389  *              authentication tokens will be retrieved
2390  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2391  *                   for the global parameters
2392  * @len: The amount written
2393  * @max: The maximum amount of data allowed to be written
2394  *
2395  * Generates a key packet set and writes it to the virtual address
2396  * passed in.
2397  *
2398  * Returns zero on success; non-zero on error.
2399  */
2400 int
2401 ecryptfs_generate_key_packet_set(char *dest_base,
2402                                  struct ecryptfs_crypt_stat *crypt_stat,
2403                                  struct dentry *ecryptfs_dentry, size_t *len,
2404                                  size_t max)
2405 {
2406         struct ecryptfs_auth_tok *auth_tok;
2407         struct key *auth_tok_key = NULL;
2408         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2409                 &ecryptfs_superblock_to_private(
2410                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2411         size_t written;
2412         struct ecryptfs_key_record *key_rec;
2413         struct ecryptfs_key_sig *key_sig;
2414         int rc = 0;
2415
2416         (*len) = 0;
2417         mutex_lock(&crypt_stat->keysig_list_mutex);
2418         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2419         if (!key_rec) {
2420                 rc = -ENOMEM;
2421                 goto out;
2422         }
2423         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2424                             crypt_stat_list) {
2425                 memset(key_rec, 0, sizeof(*key_rec));
2426                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2427                                                            &auth_tok,
2428                                                            mount_crypt_stat,
2429                                                            key_sig->keysig);
2430                 if (rc) {
2431                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2432                                "sig = [%s]\n", key_sig->keysig);
2433                         rc = process_find_global_auth_tok_for_sig_err(rc);
2434                         goto out_free;
2435                 }
2436                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2437                         rc = write_tag_3_packet((dest_base + (*len)),
2438                                                 &max, auth_tok,
2439                                                 crypt_stat, key_rec,
2440                                                 &written);
2441                         up_write(&(auth_tok_key->sem));
2442                         key_put(auth_tok_key);
2443                         if (rc) {
2444                                 ecryptfs_printk(KERN_WARNING, "Error "
2445                                                 "writing tag 3 packet\n");
2446                                 goto out_free;
2447                         }
2448                         (*len) += written;
2449                         /* Write auth tok signature packet */
2450                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2451                                                  key_rec->sig,
2452                                                  ECRYPTFS_SIG_SIZE, &written);
2453                         if (rc) {
2454                                 ecryptfs_printk(KERN_ERR, "Error writing "
2455                                                 "auth tok signature packet\n");
2456                                 goto out_free;
2457                         }
2458                         (*len) += written;
2459                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2460                         rc = write_tag_1_packet(dest_base + (*len), &max,
2461                                                 auth_tok_key, auth_tok,
2462                                                 crypt_stat, key_rec, &written);
2463                         if (rc) {
2464                                 ecryptfs_printk(KERN_WARNING, "Error "
2465                                                 "writing tag 1 packet\n");
2466                                 goto out_free;
2467                         }
2468                         (*len) += written;
2469                 } else {
2470                         up_write(&(auth_tok_key->sem));
2471                         key_put(auth_tok_key);
2472                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2473                                         "authentication token type\n");
2474                         rc = -EINVAL;
2475                         goto out_free;
2476                 }
2477         }
2478         if (likely(max > 0)) {
2479                 dest_base[(*len)] = 0x00;
2480         } else {
2481                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2482                 rc = -EIO;
2483         }
2484 out_free:
2485         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2486 out:
2487         if (rc)
2488                 (*len) = 0;
2489         mutex_unlock(&crypt_stat->keysig_list_mutex);
2490         return rc;
2491 }
2492
2493 struct kmem_cache *ecryptfs_key_sig_cache;
2494
2495 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2496 {
2497         struct ecryptfs_key_sig *new_key_sig;
2498
2499         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2500         if (!new_key_sig)
2501                 return -ENOMEM;
2502
2503         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2504         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2505         /* Caller must hold keysig_list_mutex */
2506         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2507
2508         return 0;
2509 }
2510
2511 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2512
2513 int
2514 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2515                              char *sig, u32 global_auth_tok_flags)
2516 {
2517         struct ecryptfs_global_auth_tok *new_auth_tok;
2518
2519         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2520                                         GFP_KERNEL);
2521         if (!new_auth_tok)
2522                 return -ENOMEM;
2523
2524         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2525         new_auth_tok->flags = global_auth_tok_flags;
2526         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2527         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2528         list_add(&new_auth_tok->mount_crypt_stat_list,
2529                  &mount_crypt_stat->global_auth_tok_list);
2530         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2531         return 0;
2532 }
2533