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          *         | File Encryption Key      | arbitrary    |
 304          */
 305         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
 306         *packet = kmalloc(data_len, GFP_KERNEL);
 307         message = *packet;
 308         if (!message) {
 309                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 310                 rc = -ENOMEM;
 311                 goto out;
 312         }
 313         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
 314         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 315                                           &packet_size_len);
 316         if (rc) {
 317                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 318                                 "header; cannot generate packet length\n");
 319                 goto out;
 320         }
 321         i += packet_size_len;
 322         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 323         i += ECRYPTFS_SIG_SIZE_HEX;
 324         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
 325         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
 326                                           &packet_size_len);
 327         if (rc) {
 328                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 329                                 "header; cannot generate packet length\n");
 330                 goto out;
 331         }
 332         i += packet_size_len;
 333         message[i++] = cipher_code;
 334         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
 335         i += crypt_stat->key_size;
 336         for (j = 0; j < crypt_stat->key_size; j++)
 337                 checksum += crypt_stat->key[j];
 338         message[i++] = (checksum / 256) % 256;
 339         message[i++] = (checksum % 256);
 340         *packet_len = i;
 341 out:
 342         return rc;
 343 }
 344
 345 static int
 346 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
 347                     struct ecryptfs_message *msg)
 348 {
 349         size_t i = 0;
 350         char *data;
 351         size_t data_len;
 352         size_t message_len;
 353         int rc;
 354
 355         /*
 356          *              ***** TAG 65 Packet Format *****
 357          *    | Content Type                       | 1 byte       |
 358          *    | Status Indicator                   | 1 byte       |
 359          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 360          *    | Encrypted File Encryption Key      | arbitrary    |
 361          */
 362         message_len = msg->data_len;
 363         data = msg->data;
 364         /* verify that everything through the encrypted FEK size is present */
 365         if (message_len < 4) {
 366                 rc = -EIO;
 367                 printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
 368                        "message length is [%d]\n", __func__, message_len, 4);
 369                 goto out;
 370         }
 371         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
 372                 rc = -EIO;
 373                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
 374                        __func__);
 375                 goto out;
 376         }
 377         if (data[i++]) {
 378                 rc = -EIO;
 379                 printk(KERN_ERR "%s: Status indicator has non zero "
 380                        "value [%d]\n", __func__, data[i-1]);
 381
 382                 goto out;
 383         }
 384         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
 385                                           &data_len);
 386         if (rc) {
 387                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 388                                 "rc = [%d]\n", rc);
 389                 goto out;
 390         }
 391         i += data_len;
 392         if (message_len < (i + key_rec->enc_key_size)) {
 393                 rc = -EIO;
 394                 printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
 395                        __func__, message_len, (i + key_rec->enc_key_size));
 396                 goto out;
 397         }
 398         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
 399                 rc = -EIO;
 400                 printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
 401                        "the maximum key size [%d]\n", __func__,
 402                        key_rec->enc_key_size,
 403                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 404                 goto out;
 405         }
 406         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
 407 out:
 408         return rc;
 409 }
 410
 411 /**
 412  * ecryptfs_verify_version
 413  * @version: The version number to confirm
 414  *
 415  * Returns zero on good version; non-zero otherwise
 416  */
 417 static int ecryptfs_verify_version(u16 version)
 418 {
 419         int rc = 0;
 420         unsigned char major;
 421         unsigned char minor;
 422
 423         major = ((version >> 8) & 0xFF);
 424         minor = (version & 0xFF);
 425         if (major != ECRYPTFS_VERSION_MAJOR) {
 426                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
 427                                 "Expected [%d]; got [%d]\n",
 428                                 ECRYPTFS_VERSION_MAJOR, major);
 429                 rc = -EINVAL;
 430                 goto out;
 431         }
 432         if (minor != ECRYPTFS_VERSION_MINOR) {
 433                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
 434                                 "Expected [%d]; got [%d]\n",
 435                                 ECRYPTFS_VERSION_MINOR, minor);
 436                 rc = -EINVAL;
 437                 goto out;
 438         }
 439 out:
 440         return rc;
 441 }
 442
 443 /**
 444  * ecryptfs_verify_auth_tok_from_key
 445  * @auth_tok_key: key containing the authentication token
 446  * @auth_tok: authentication token
 447  *
 448  * Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
 449  * -EKEYREVOKED if the key was revoked before we acquired its semaphore.
 450  */
 451 static int
 452 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
 453                                   struct ecryptfs_auth_tok **auth_tok)
 454 {
 455         int rc = 0;
 456
 457         (*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
 458         if (IS_ERR(*auth_tok)) {
 459                 rc = PTR_ERR(*auth_tok);
 460                 *auth_tok = NULL;
 461                 goto out;
 462         }
 463
 464         if (ecryptfs_verify_version((*auth_tok)->version)) {
 465                 printk(KERN_ERR "Data structure version mismatch. Userspace "
 466                        "tools must match eCryptfs kernel module with major "
 467                        "version [%d] and minor version [%d]\n",
 468                        ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
 469                 rc = -EINVAL;
 470                 goto out;
 471         }
 472         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
 473             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
 474                 printk(KERN_ERR "Invalid auth_tok structure "
 475                        "returned from key query\n");
 476                 rc = -EINVAL;
 477                 goto out;
 478         }
 479 out:
 480         return rc;
 481 }
 482
 483 static int
 484 ecryptfs_find_global_auth_tok_for_sig(
 485         struct key **auth_tok_key,
 486         struct ecryptfs_auth_tok **auth_tok,
 487         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
 488 {
 489         struct ecryptfs_global_auth_tok *walker;
 490         int rc = 0;
 491
 492         (*auth_tok_key) = NULL;
 493         (*auth_tok) = NULL;
 494         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 495         list_for_each_entry(walker,
 496                             &mount_crypt_stat->global_auth_tok_list,
 497                             mount_crypt_stat_list) {
 498                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
 499                         continue;
 500
 501                 if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
 502                         rc = -EINVAL;
 503                         goto out;
 504                 }
 505
 506                 rc = key_validate(walker->global_auth_tok_key);
 507                 if (rc) {
 508                         if (rc == -EKEYEXPIRED)
 509                                 goto out;
 510                         goto out_invalid_auth_tok;
 511                 }
 512
 513                 down_write(&(walker->global_auth_tok_key->sem));
 514                 rc = ecryptfs_verify_auth_tok_from_key(
 515                                 walker->global_auth_tok_key, auth_tok);
 516                 if (rc)
 517                         goto out_invalid_auth_tok_unlock;
 518
 519                 (*auth_tok_key) = walker->global_auth_tok_key;
 520                 key_get(*auth_tok_key);
 521                 goto out;
 522         }
 523         rc = -ENOENT;
 524         goto out;
 525 out_invalid_auth_tok_unlock:
 526         up_write(&(walker->global_auth_tok_key->sem));
 527 out_invalid_auth_tok:
 528         printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
 529         walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
 530         key_put(walker->global_auth_tok_key);
 531         walker->global_auth_tok_key = NULL;
 532 out:
 533         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 534         return rc;
 535 }
 536
 537 /**
 538  * ecryptfs_find_auth_tok_for_sig
 539  * @auth_tok: Set to the matching auth_tok; NULL if not found
 540  * @crypt_stat: inode crypt_stat crypto context
 541  * @sig: Sig of auth_tok to find
 542  *
 543  * For now, this function simply looks at the registered auth_tok's
 544  * linked off the mount_crypt_stat, so all the auth_toks that can be
 545  * used must be registered at mount time. This function could
 546  * potentially try a lot harder to find auth_tok's (e.g., by calling
 547  * out to ecryptfsd to dynamically retrieve an auth_tok object) so
 548  * that static registration of auth_tok's will no longer be necessary.
 549  *
 550  * Returns zero on no error; non-zero on error
 551  */
 552 static int
 553 ecryptfs_find_auth_tok_for_sig(
 554         struct key **auth_tok_key,
 555         struct ecryptfs_auth_tok **auth_tok,
 556         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 557         char *sig)
 558 {
 559         int rc = 0;
 560
 561         rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
 562                                                    mount_crypt_stat, sig);
 563         if (rc == -ENOENT) {
 564                 /* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
 565                  * mount_crypt_stat structure, we prevent to use auth toks that
 566                  * are not inserted through the ecryptfs_add_global_auth_tok
 567                  * function.
 568                  */
 569                 if (mount_crypt_stat->flags
 570                                 & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 571                         return -EINVAL;
 572
 573                 rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
 574                                                        sig);
 575         }
 576         return rc;
 577 }
 578
 579 /**
 580  * write_tag_70_packet can gobble a lot of stack space. We stuff most
 581  * of the function's parameters in a kmalloc'd struct to help reduce
 582  * eCryptfs' overall stack usage.
 583  */
 584 struct ecryptfs_write_tag_70_packet_silly_stack {
 585         u8 cipher_code;
 586         size_t max_packet_size;
 587         size_t packet_size_len;
 588         size_t block_aligned_filename_size;
 589         size_t block_size;
 590         size_t i;
 591         size_t j;
 592         size_t num_rand_bytes;
 593         struct mutex *tfm_mutex;
 594         char *block_aligned_filename;
 595         struct ecryptfs_auth_tok *auth_tok;
 596         struct scatterlist src_sg[2];
 597         struct scatterlist dst_sg[2];
 598         struct crypto_skcipher *skcipher_tfm;
 599         struct skcipher_request *skcipher_req;
 600         char iv[ECRYPTFS_MAX_IV_BYTES];
 601         char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 602         char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 603         struct crypto_shash *hash_tfm;
 604         struct shash_desc *hash_desc;
 605 };
 606
 607 /**
 608  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
 609  * @filename: NULL-terminated filename string
 610  *
 611  * This is the simplest mechanism for achieving filename encryption in
 612  * eCryptfs. It encrypts the given filename with the mount-wide
 613  * filename encryption key (FNEK) and stores it in a packet to @dest,
 614  * which the callee will encode and write directly into the dentry
 615  * name.
 616  */
 617 int
 618 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 619                              size_t *packet_size,
 620                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 621                              char *filename, size_t filename_size)
 622 {
 623         struct ecryptfs_write_tag_70_packet_silly_stack *s;
 624         struct key *auth_tok_key = NULL;
 625         int rc = 0;
 626
 627         s = kzalloc(sizeof(*s), GFP_KERNEL);
 628         if (!s)
 629                 return -ENOMEM;
 630
 631         (*packet_size) = 0;
 632         rc = ecryptfs_find_auth_tok_for_sig(
 633                 &auth_tok_key,
 634                 &s->auth_tok, mount_crypt_stat,
 635                 mount_crypt_stat->global_default_fnek_sig);
 636         if (rc) {
 637                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 638                        "fnek sig [%s]; rc = [%d]\n", __func__,
 639                        mount_crypt_stat->global_default_fnek_sig, rc);
 640                 goto out;
 641         }
 642         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
 643                 &s->skcipher_tfm,
 644                 &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
 645         if (unlikely(rc)) {
 646                 printk(KERN_ERR "Internal error whilst attempting to get "
 647                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 648                        mount_crypt_stat->global_default_fn_cipher_name, rc);
 649                 goto out;
 650         }
 651         mutex_lock(s->tfm_mutex);
 652         s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
 653         /* Plus one for the \0 separator between the random prefix
 654          * and the plaintext filename */
 655         s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
 656         s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
 657         if ((s->block_aligned_filename_size % s->block_size) != 0) {
 658                 s->num_rand_bytes += (s->block_size
 659                                       - (s->block_aligned_filename_size
 660                                          % s->block_size));
 661                 s->block_aligned_filename_size = (s->num_rand_bytes
 662                                                   + filename_size);
 663         }
 664         /* Octet 0: Tag 70 identifier
 665          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 666          *              and block-aligned encrypted filename size)
 667          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 668          * Octet N2-N3: Cipher identifier (1 octet)
 669          * Octets N3-N4: Block-aligned encrypted filename
 670          *  - Consists of a minimum number of random characters, a \0
 671          *    separator, and then the filename */
 672         s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
 673                               + s->block_aligned_filename_size);
 674         if (!dest) {
 675                 (*packet_size) = s->max_packet_size;
 676                 goto out_unlock;
 677         }
 678         if (s->max_packet_size > (*remaining_bytes)) {
 679                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
 680                        "[%zd] available\n", __func__, s->max_packet_size,
 681                        (*remaining_bytes));
 682                 rc = -EINVAL;
 683                 goto out_unlock;
 684         }
 685
 686         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
 687         if (!s->skcipher_req) {
 688                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
 689                        "skcipher_request_alloc for %s\n", __func__,
 690                        crypto_skcipher_driver_name(s->skcipher_tfm));
 691                 rc = -ENOMEM;
 692                 goto out_unlock;
 693         }
 694
 695         skcipher_request_set_callback(s->skcipher_req,
 696                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 697
 698         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
 699                                             GFP_KERNEL);
 700         if (!s->block_aligned_filename) {
 701                 rc = -ENOMEM;
 702                 goto out_unlock;
 703         }
 704         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
 705         rc = ecryptfs_write_packet_length(&dest[s->i],
 706                                           (ECRYPTFS_SIG_SIZE
 707                                            + 1 /* Cipher code */
 708                                            + s->block_aligned_filename_size),
 709                                           &s->packet_size_len);
 710         if (rc) {
 711                 printk(KERN_ERR "%s: Error generating tag 70 packet "
 712                        "header; cannot generate packet length; rc = [%d]\n",
 713                        __func__, rc);
 714                 goto out_free_unlock;
 715         }
 716         s->i += s->packet_size_len;
 717         ecryptfs_from_hex(&dest[s->i],
 718                           mount_crypt_stat->global_default_fnek_sig,
 719                           ECRYPTFS_SIG_SIZE);
 720         s->i += ECRYPTFS_SIG_SIZE;
 721         s->cipher_code = ecryptfs_code_for_cipher_string(
 722                 mount_crypt_stat->global_default_fn_cipher_name,
 723                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 724         if (s->cipher_code == 0) {
 725                 printk(KERN_WARNING "%s: Unable to generate code for "
 726                        "cipher [%s] with key bytes [%zd]\n", __func__,
 727                        mount_crypt_stat->global_default_fn_cipher_name,
 728                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 729                 rc = -EINVAL;
 730                 goto out_free_unlock;
 731         }
 732         dest[s->i++] = s->cipher_code;
 733         /* TODO: Support other key modules than passphrase for
 734          * filename encryption */
 735         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
 736                 rc = -EOPNOTSUPP;
 737                 printk(KERN_INFO "%s: Filename encryption only supports "
 738                        "password tokens\n", __func__);
 739                 goto out_free_unlock;
 740         }
 741         s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
 742         if (IS_ERR(s->hash_tfm)) {
 743                         rc = PTR_ERR(s->hash_tfm);
 744                         printk(KERN_ERR "%s: Error attempting to "
 745                                "allocate hash crypto context; rc = [%d]\n",
 746                                __func__, rc);
 747                         goto out_free_unlock;
 748         }
 749
 750         s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
 751                                crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
 752         if (!s->hash_desc) {
 753                 rc = -ENOMEM;
 754                 goto out_release_free_unlock;
 755         }
 756
 757         s->hash_desc->tfm = s->hash_tfm;
 758
 759         rc = crypto_shash_digest(s->hash_desc,
 760                                  (u8 *)s->auth_tok->token.password.session_key_encryption_key,
 761                                  s->auth_tok->token.password.session_key_encryption_key_bytes,
 762                                  s->hash);
 763         if (rc) {
 764                 printk(KERN_ERR
 765                        "%s: Error computing crypto hash; rc = [%d]\n",
 766                        __func__, rc);
 767                 goto out_release_free_unlock;
 768         }
 769         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
 770                 s->block_aligned_filename[s->j] =
 771                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
 772                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
 773                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
 774                         rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
 775                                                 ECRYPTFS_TAG_70_DIGEST_SIZE,
 776                                                 s->tmp_hash);
 777                         if (rc) {
 778                                 printk(KERN_ERR
 779                                        "%s: Error computing crypto hash; "
 780                                        "rc = [%d]\n", __func__, rc);
 781                                 goto out_release_free_unlock;
 782                         }
 783                         memcpy(s->hash, s->tmp_hash,
 784                                ECRYPTFS_TAG_70_DIGEST_SIZE);
 785                 }
 786                 if (s->block_aligned_filename[s->j] == '\0')
 787                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
 788         }
 789         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 790                filename_size);
 791         rc = virt_to_scatterlist(s->block_aligned_filename,
 792                                  s->block_aligned_filename_size, s->src_sg, 2);
 793         if (rc < 1) {
 794                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 795                        "convert filename memory to scatterlist; rc = [%d]. "
 796                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 797                        s->block_aligned_filename_size);
 798                 goto out_release_free_unlock;
 799         }
 800         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
 801                                  s->dst_sg, 2);
 802         if (rc < 1) {
 803                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 804                        "convert encrypted filename memory to scatterlist; "
 805                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 806                        __func__, rc, s->block_aligned_filename_size);
 807                 goto out_release_free_unlock;
 808         }
 809         /* The characters in the first block effectively do the job
 810          * of the IV here, so we just use 0's for the IV. Note the
 811          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
 812          * >= ECRYPTFS_MAX_IV_BYTES. */
 813         rc = crypto_skcipher_setkey(
 814                 s->skcipher_tfm,
 815                 s->auth_tok->token.password.session_key_encryption_key,
 816                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 817         if (rc < 0) {
 818                 printk(KERN_ERR "%s: Error setting key for crypto context; "
 819                        "rc = [%d]. s->auth_tok->token.password.session_key_"
 820                        "encryption_key = [0x%p]; mount_crypt_stat->"
 821                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
 822                        rc,
 823                        s->auth_tok->token.password.session_key_encryption_key,
 824                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 825                 goto out_release_free_unlock;
 826         }
 827         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
 828                                    s->block_aligned_filename_size, s->iv);
 829         rc = crypto_skcipher_encrypt(s->skcipher_req);
 830         if (rc) {
 831                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
 832                        "rc = [%d]\n", __func__, rc);
 833                 goto out_release_free_unlock;
 834         }
 835         s->i += s->block_aligned_filename_size;
 836         (*packet_size) = s->i;
 837         (*remaining_bytes) -= (*packet_size);
 838 out_release_free_unlock:
 839         crypto_free_shash(s->hash_tfm);
 840 out_free_unlock:
 841         kzfree(s->block_aligned_filename);
 842 out_unlock:
 843         mutex_unlock(s->tfm_mutex);
 844 out:
 845         if (auth_tok_key) {
 846                 up_write(&(auth_tok_key->sem));
 847                 key_put(auth_tok_key);
 848         }
 849         skcipher_request_free(s->skcipher_req);
 850         kzfree(s->hash_desc);
 851         kfree(s);
 852         return rc;
 853 }
 854
 855 struct ecryptfs_parse_tag_70_packet_silly_stack {
 856         u8 cipher_code;
 857         size_t max_packet_size;
 858         size_t packet_size_len;
 859         size_t parsed_tag_70_packet_size;
 860         size_t block_aligned_filename_size;
 861         size_t block_size;
 862         size_t i;
 863         struct mutex *tfm_mutex;
 864         char *decrypted_filename;
 865         struct ecryptfs_auth_tok *auth_tok;
 866         struct scatterlist src_sg[2];
 867         struct scatterlist dst_sg[2];
 868         struct crypto_skcipher *skcipher_tfm;
 869         struct skcipher_request *skcipher_req;
 870         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 871         char iv[ECRYPTFS_MAX_IV_BYTES];
 872         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
 873 };
 874
 875 /**
 876  * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 877  * @filename: This function kmalloc's the memory for the filename
 878  * @filename_size: This function sets this to the amount of memory
 879  *                 kmalloc'd for the filename
 880  * @packet_size: This function sets this to the the number of octets
 881  *               in the packet parsed
 882  * @mount_crypt_stat: The mount-wide cryptographic context
 883  * @data: The memory location containing the start of the tag 70
 884  *        packet
 885  * @max_packet_size: The maximum legal size of the packet to be parsed
 886  *                   from @data
 887  *
 888  * Returns zero on success; non-zero otherwise
 889  */
 890 int
 891 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 892                              size_t *packet_size,
 893                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 894                              char *data, size_t max_packet_size)
 895 {
 896         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
 897         struct key *auth_tok_key = NULL;
 898         int rc = 0;
 899
 900         (*packet_size) = 0;
 901         (*filename_size) = 0;
 902         (*filename) = NULL;
 903         s = kzalloc(sizeof(*s), GFP_KERNEL);
 904         if (!s)
 905                 return -ENOMEM;
 906
 907         if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
 908                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
 909                        "at least [%d]\n", __func__, max_packet_size,
 910                        ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
 911                 rc = -EINVAL;
 912                 goto out;
 913         }
 914         /* Octet 0: Tag 70 identifier
 915          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 916          *              and block-aligned encrypted filename size)
 917          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 918          * Octet N2-N3: Cipher identifier (1 octet)
 919          * Octets N3-N4: Block-aligned encrypted filename
 920          *  - Consists of a minimum number of random numbers, a \0
 921          *    separator, and then the filename */
 922         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
 923                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
 924                        "tag [0x%.2x]\n", __func__,
 925                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
 926                 rc = -EINVAL;
 927                 goto out;
 928         }
 929         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
 930                                           &s->parsed_tag_70_packet_size,
 931                                           &s->packet_size_len);
 932         if (rc) {
 933                 printk(KERN_WARNING "%s: Error parsing packet length; "
 934                        "rc = [%d]\n", __func__, rc);
 935                 goto out;
 936         }
 937         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
 938                                           - ECRYPTFS_SIG_SIZE - 1);
 939         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
 940             > max_packet_size) {
 941                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
 942                        "size is [%zd]\n", __func__, max_packet_size,
 943                        (1 + s->packet_size_len + 1
 944                         + s->block_aligned_filename_size));
 945                 rc = -EINVAL;
 946                 goto out;
 947         }
 948         (*packet_size) += s->packet_size_len;
 949         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
 950                         ECRYPTFS_SIG_SIZE);
 951         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 952         (*packet_size) += ECRYPTFS_SIG_SIZE;
 953         s->cipher_code = data[(*packet_size)++];
 954         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
 955         if (rc) {
 956                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
 957                        __func__, s->cipher_code);
 958                 goto out;
 959         }
 960         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
 961                                             &s->auth_tok, mount_crypt_stat,
 962                                             s->fnek_sig_hex);
 963         if (rc) {
 964                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 965                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
 966                        rc);
 967                 goto out;
 968         }
 969         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
 970                                                         &s->tfm_mutex,
 971                                                         s->cipher_string);
 972         if (unlikely(rc)) {
 973                 printk(KERN_ERR "Internal error whilst attempting to get "
 974                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 975                        s->cipher_string, rc);
 976                 goto out;
 977         }
 978         mutex_lock(s->tfm_mutex);
 979         rc = virt_to_scatterlist(&data[(*packet_size)],
 980                                  s->block_aligned_filename_size, s->src_sg, 2);
 981         if (rc < 1) {
 982                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 983                        "convert encrypted filename memory to scatterlist; "
 984                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 985                        __func__, rc, s->block_aligned_filename_size);
 986                 goto out_unlock;
 987         }
 988         (*packet_size) += s->block_aligned_filename_size;
 989         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
 990                                         GFP_KERNEL);
 991         if (!s->decrypted_filename) {
 992                 rc = -ENOMEM;
 993                 goto out_unlock;
 994         }
 995         rc = virt_to_scatterlist(s->decrypted_filename,
 996                                  s->block_aligned_filename_size, s->dst_sg, 2);
 997         if (rc < 1) {
 998                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 999                        "convert decrypted filename memory to scatterlist; "
1000                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1001                        __func__, rc, s->block_aligned_filename_size);
1002                 goto out_free_unlock;
1003         }
1004
1005         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
1006         if (!s->skcipher_req) {
1007                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1008                        "skcipher_request_alloc for %s\n", __func__,
1009                        crypto_skcipher_driver_name(s->skcipher_tfm));
1010                 rc = -ENOMEM;
1011                 goto out_free_unlock;
1012         }
1013
1014         skcipher_request_set_callback(s->skcipher_req,
1015                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
1016
1017         /* The characters in the first block effectively do the job of
1018          * the IV here, so we just use 0's for the IV. Note the
1019          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1020          * >= ECRYPTFS_MAX_IV_BYTES. */
1021         /* TODO: Support other key modules than passphrase for
1022          * filename encryption */
1023         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1024                 rc = -EOPNOTSUPP;
1025                 printk(KERN_INFO "%s: Filename encryption only supports "
1026                        "password tokens\n", __func__);
1027                 goto out_free_unlock;
1028         }
1029         rc = crypto_skcipher_setkey(
1030                 s->skcipher_tfm,
1031                 s->auth_tok->token.password.session_key_encryption_key,
1032                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1033         if (rc < 0) {
1034                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1035                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1036                        "encryption_key = [0x%p]; mount_crypt_stat->"
1037                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1038                        rc,
1039                        s->auth_tok->token.password.session_key_encryption_key,
1040                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1041                 goto out_free_unlock;
1042         }
1043         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
1044                                    s->block_aligned_filename_size, s->iv);
1045         rc = crypto_skcipher_decrypt(s->skcipher_req);
1046         if (rc) {
1047                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1048                        "rc = [%d]\n", __func__, rc);
1049                 goto out_free_unlock;
1050         }
1051         while (s->decrypted_filename[s->i] != '\0'
1052                && s->i < s->block_aligned_filename_size)
1053                 s->i++;
1054         if (s->i == s->block_aligned_filename_size) {
1055                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1056                        "find valid separator between random characters and "
1057                        "the filename\n", __func__);
1058                 rc = -EINVAL;
1059                 goto out_free_unlock;
1060         }
1061         s->i++;
1062         (*filename_size) = (s->block_aligned_filename_size - s->i);
1063         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1064                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1065                        "invalid\n", __func__, (*filename_size));
1066                 rc = -EINVAL;
1067                 goto out_free_unlock;
1068         }
1069         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1070         if (!(*filename)) {
1071                 rc = -ENOMEM;
1072                 goto out_free_unlock;
1073         }
1074         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1075         (*filename)[(*filename_size)] = '\0';
1076 out_free_unlock:
1077         kfree(s->decrypted_filename);
1078 out_unlock:
1079         mutex_unlock(s->tfm_mutex);
1080 out:
1081         if (rc) {
1082                 (*packet_size) = 0;
1083                 (*filename_size) = 0;
1084                 (*filename) = NULL;
1085         }
1086         if (auth_tok_key) {
1087                 up_write(&(auth_tok_key->sem));
1088                 key_put(auth_tok_key);
1089         }
1090         skcipher_request_free(s->skcipher_req);
1091         kfree(s);
1092         return rc;
1093 }
1094
1095 static int
1096 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1097 {
1098         int rc = 0;
1099
1100         (*sig) = NULL;
1101         switch (auth_tok->token_type) {
1102         case ECRYPTFS_PASSWORD:
1103                 (*sig) = auth_tok->token.password.signature;
1104                 break;
1105         case ECRYPTFS_PRIVATE_KEY:
1106                 (*sig) = auth_tok->token.private_key.signature;
1107                 break;
1108         default:
1109                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1110                        auth_tok->token_type);
1111                 rc = -EINVAL;
1112         }
1113         return rc;
1114 }
1115
1116 /**
1117  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1118  * @auth_tok: The key authentication token used to decrypt the session key
1119  * @crypt_stat: The cryptographic context
1120  *
1121  * Returns zero on success; non-zero error otherwise.
1122  */
1123 static int
1124 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1125                                   struct ecryptfs_crypt_stat *crypt_stat)
1126 {
1127         u8 cipher_code = 0;
1128         struct ecryptfs_msg_ctx *msg_ctx;
1129         struct ecryptfs_message *msg = NULL;
1130         char *auth_tok_sig;
1131         char *payload = NULL;
1132         size_t payload_len = 0;
1133         int rc;
1134
1135         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1136         if (rc) {
1137                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1138                        auth_tok->token_type);
1139                 goto out;
1140         }
1141         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1142                                  &payload, &payload_len);
1143         if (rc) {
1144                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1145                 goto out;
1146         }
1147         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1148         if (rc) {
1149                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1150                                 "ecryptfsd: %d\n", rc);
1151                 goto out;
1152         }
1153         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1154         if (rc) {
1155                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1156                                 "from the user space daemon\n");
1157                 rc = -EIO;
1158                 goto out;
1159         }
1160         rc = parse_tag_65_packet(&(auth_tok->session_key),
1161                                  &cipher_code, msg);
1162         if (rc) {
1163                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1164                        rc);
1165                 goto out;
1166         }
1167         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1168         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1169                auth_tok->session_key.decrypted_key_size);
1170         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1171         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1172         if (rc) {
1173                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1174                                 cipher_code)
1175                 goto out;
1176         }
1177         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1178         if (ecryptfs_verbosity > 0) {
1179                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1180                 ecryptfs_dump_hex(crypt_stat->key,
1181                                   crypt_stat->key_size);
1182         }
1183 out:
1184         kfree(msg);
1185         kfree(payload);
1186         return rc;
1187 }
1188
1189 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1190 {
1191         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1192         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1193
1194         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1195                                  auth_tok_list_head, list) {
1196                 list_del(&auth_tok_list_item->list);
1197                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1198                                 auth_tok_list_item);
1199         }
1200 }
1201
1202 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1203
1204 /**
1205  * parse_tag_1_packet
1206  * @crypt_stat: The cryptographic context to modify based on packet contents
1207  * @data: The raw bytes of the packet.
1208  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1209  *                 a new authentication token will be placed at the
1210  *                 end of this list for this packet.
1211  * @new_auth_tok: Pointer to a pointer to memory that this function
1212  *                allocates; sets the memory address of the pointer to
1213  *                NULL on error. This object is added to the
1214  *                auth_tok_list.
1215  * @packet_size: This function writes the size of the parsed packet
1216  *               into this memory location; zero on error.
1217  * @max_packet_size: The maximum allowable packet size
1218  *
1219  * Returns zero on success; non-zero on error.
1220  */
1221 static int
1222 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1223                    unsigned char *data, struct list_head *auth_tok_list,
1224                    struct ecryptfs_auth_tok **new_auth_tok,
1225                    size_t *packet_size, size_t max_packet_size)
1226 {
1227         size_t body_size;
1228         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1229         size_t length_size;
1230         int rc = 0;
1231
1232         (*packet_size) = 0;
1233         (*new_auth_tok) = NULL;
1234         /**
1235          * This format is inspired by OpenPGP; see RFC 2440
1236          * packet tag 1
1237          *
1238          * Tag 1 identifier (1 byte)
1239          * Max Tag 1 packet size (max 3 bytes)
1240          * Version (1 byte)
1241          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1242          * Cipher identifier (1 byte)
1243          * Encrypted key size (arbitrary)
1244          *
1245          * 12 bytes minimum packet size
1246          */
1247         if (unlikely(max_packet_size < 12)) {
1248                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1249                 rc = -EINVAL;
1250                 goto out;
1251         }
1252         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1253                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1254                        ECRYPTFS_TAG_1_PACKET_TYPE);
1255                 rc = -EINVAL;
1256                 goto out;
1257         }
1258         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1259          * at end of function upon failure */
1260         auth_tok_list_item =
1261                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1262                                   GFP_KERNEL);
1263         if (!auth_tok_list_item) {
1264                 printk(KERN_ERR "Unable to allocate memory\n");
1265                 rc = -ENOMEM;
1266                 goto out;
1267         }
1268         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1269         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1270                                           &length_size);
1271         if (rc) {
1272                 printk(KERN_WARNING "Error parsing packet length; "
1273                        "rc = [%d]\n", rc);
1274                 goto out_free;
1275         }
1276         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1277                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1278                 rc = -EINVAL;
1279                 goto out_free;
1280         }
1281         (*packet_size) += length_size;
1282         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1283                 printk(KERN_WARNING "Packet size exceeds max\n");
1284                 rc = -EINVAL;
1285                 goto out_free;
1286         }
1287         if (unlikely(data[(*packet_size)++] != 0x03)) {
1288                 printk(KERN_WARNING "Unknown version number [%d]\n",
1289                        data[(*packet_size) - 1]);
1290                 rc = -EINVAL;
1291                 goto out_free;
1292         }
1293         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1294                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1295         *packet_size += ECRYPTFS_SIG_SIZE;
1296         /* This byte is skipped because the kernel does not need to
1297          * know which public key encryption algorithm was used */
1298         (*packet_size)++;
1299         (*new_auth_tok)->session_key.encrypted_key_size =
1300                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1301         if ((*new_auth_tok)->session_key.encrypted_key_size
1302             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1303                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1304                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1305                 rc = -EINVAL;
1306                 goto out;
1307         }
1308         memcpy((*new_auth_tok)->session_key.encrypted_key,
1309                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1310         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1311         (*new_auth_tok)->session_key.flags &=
1312                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1313         (*new_auth_tok)->session_key.flags |=
1314                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1315         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1316         (*new_auth_tok)->flags = 0;
1317         (*new_auth_tok)->session_key.flags &=
1318                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1319         (*new_auth_tok)->session_key.flags &=
1320                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1321         list_add(&auth_tok_list_item->list, auth_tok_list);
1322         goto out;
1323 out_free:
1324         (*new_auth_tok) = NULL;
1325         memset(auth_tok_list_item, 0,
1326                sizeof(struct ecryptfs_auth_tok_list_item));
1327         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1328                         auth_tok_list_item);
1329 out:
1330         if (rc)
1331                 (*packet_size) = 0;
1332         return rc;
1333 }
1334
1335 /**
1336  * parse_tag_3_packet
1337  * @crypt_stat: The cryptographic context to modify based on packet
1338  *              contents.
1339  * @data: The raw bytes of the packet.
1340  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1341  *                 a new authentication token will be placed at the end
1342  *                 of this list for this packet.
1343  * @new_auth_tok: Pointer to a pointer to memory that this function
1344  *                allocates; sets the memory address of the pointer to
1345  *                NULL on error. This object is added to the
1346  *                auth_tok_list.
1347  * @packet_size: This function writes the size of the parsed packet
1348  *               into this memory location; zero on error.
1349  * @max_packet_size: maximum number of bytes to parse
1350  *
1351  * Returns zero on success; non-zero on error.
1352  */
1353 static int
1354 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1355                    unsigned char *data, struct list_head *auth_tok_list,
1356                    struct ecryptfs_auth_tok **new_auth_tok,
1357                    size_t *packet_size, size_t max_packet_size)
1358 {
1359         size_t body_size;
1360         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1361         size_t length_size;
1362         int rc = 0;
1363
1364         (*packet_size) = 0;
1365         (*new_auth_tok) = NULL;
1366         /**
1367          *This format is inspired by OpenPGP; see RFC 2440
1368          * packet tag 3
1369          *
1370          * Tag 3 identifier (1 byte)
1371          * Max Tag 3 packet size (max 3 bytes)
1372          * Version (1 byte)
1373          * Cipher code (1 byte)
1374          * S2K specifier (1 byte)
1375          * Hash identifier (1 byte)
1376          * Salt (ECRYPTFS_SALT_SIZE)
1377          * Hash iterations (1 byte)
1378          * Encrypted key (arbitrary)
1379          *
1380          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1381          */
1382         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1383                 printk(KERN_ERR "Max packet size too large\n");
1384                 rc = -EINVAL;
1385                 goto out;
1386         }
1387         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1388                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1389                        ECRYPTFS_TAG_3_PACKET_TYPE);
1390                 rc = -EINVAL;
1391                 goto out;
1392         }
1393         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1394          * at end of function upon failure */
1395         auth_tok_list_item =
1396             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1397         if (!auth_tok_list_item) {
1398                 printk(KERN_ERR "Unable to allocate memory\n");
1399                 rc = -ENOMEM;
1400                 goto out;
1401         }
1402         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1403         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1404                                           &length_size);
1405         if (rc) {
1406                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1407                        rc);
1408                 goto out_free;
1409         }
1410         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1411                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1412                 rc = -EINVAL;
1413                 goto out_free;
1414         }
1415         (*packet_size) += length_size;
1416         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1417                 printk(KERN_ERR "Packet size exceeds max\n");
1418                 rc = -EINVAL;
1419                 goto out_free;
1420         }
1421         (*new_auth_tok)->session_key.encrypted_key_size =
1422                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1423         if ((*new_auth_tok)->session_key.encrypted_key_size
1424             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1425                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1426                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1427                 rc = -EINVAL;
1428                 goto out_free;
1429         }
1430         if (unlikely(data[(*packet_size)++] != 0x04)) {
1431                 printk(KERN_WARNING "Unknown version number [%d]\n",
1432                        data[(*packet_size) - 1]);
1433                 rc = -EINVAL;
1434                 goto out_free;
1435         }
1436         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1437                                             (u16)data[(*packet_size)]);
1438         if (rc)
1439                 goto out_free;
1440         /* A little extra work to differentiate among the AES key
1441          * sizes; see RFC2440 */
1442         switch(data[(*packet_size)++]) {
1443         case RFC2440_CIPHER_AES_192:
1444                 crypt_stat->key_size = 24;
1445                 break;
1446         default:
1447                 crypt_stat->key_size =
1448                         (*new_auth_tok)->session_key.encrypted_key_size;
1449         }
1450         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1451         if (rc)
1452                 goto out_free;
1453         if (unlikely(data[(*packet_size)++] != 0x03)) {
1454                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1455                 rc = -ENOSYS;
1456                 goto out_free;
1457         }
1458         /* TODO: finish the hash mapping */
1459         switch (data[(*packet_size)++]) {
1460         case 0x01: /* See RFC2440 for these numbers and their mappings */
1461                 /* Choose MD5 */
1462                 memcpy((*new_auth_tok)->token.password.salt,
1463                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1464                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1465                 /* This conversion was taken straight from RFC2440 */
1466                 (*new_auth_tok)->token.password.hash_iterations =
1467                         ((u32) 16 + (data[(*packet_size)] & 15))
1468                                 << ((data[(*packet_size)] >> 4) + 6);
1469                 (*packet_size)++;
1470                 /* Friendly reminder:
1471                  * (*new_auth_tok)->session_key.encrypted_key_size =
1472                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1473                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1474                        &data[(*packet_size)],
1475                        (*new_auth_tok)->session_key.encrypted_key_size);
1476                 (*packet_size) +=
1477                         (*new_auth_tok)->session_key.encrypted_key_size;
1478                 (*new_auth_tok)->session_key.flags &=
1479                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1480                 (*new_auth_tok)->session_key.flags |=
1481                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1482                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1483                 break;
1484         default:
1485                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1486                                 "[%d]\n", data[(*packet_size) - 1]);
1487                 rc = -ENOSYS;
1488                 goto out_free;
1489         }
1490         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1491         /* TODO: Parametarize; we might actually want userspace to
1492          * decrypt the session key. */
1493         (*new_auth_tok)->session_key.flags &=
1494                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1495         (*new_auth_tok)->session_key.flags &=
1496                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1497         list_add(&auth_tok_list_item->list, auth_tok_list);
1498         goto out;
1499 out_free:
1500         (*new_auth_tok) = NULL;
1501         memset(auth_tok_list_item, 0,
1502                sizeof(struct ecryptfs_auth_tok_list_item));
1503         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1504                         auth_tok_list_item);
1505 out:
1506         if (rc)
1507                 (*packet_size) = 0;
1508         return rc;
1509 }
1510
1511 /**
1512  * parse_tag_11_packet
1513  * @data: The raw bytes of the packet
1514  * @contents: This function writes the data contents of the literal
1515  *            packet into this memory location
1516  * @max_contents_bytes: The maximum number of bytes that this function
1517  *                      is allowed to write into contents
1518  * @tag_11_contents_size: This function writes the size of the parsed
1519  *                        contents into this memory location; zero on
1520  *                        error
1521  * @packet_size: This function writes the size of the parsed packet
1522  *               into this memory location; zero on error
1523  * @max_packet_size: maximum number of bytes to parse
1524  *
1525  * Returns zero on success; non-zero on error.
1526  */
1527 static int
1528 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1529                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1530                     size_t *packet_size, size_t max_packet_size)
1531 {
1532         size_t body_size;
1533         size_t length_size;
1534         int rc = 0;
1535
1536         (*packet_size) = 0;
1537         (*tag_11_contents_size) = 0;
1538         /* This format is inspired by OpenPGP; see RFC 2440
1539          * packet tag 11
1540          *
1541          * Tag 11 identifier (1 byte)
1542          * Max Tag 11 packet size (max 3 bytes)
1543          * Binary format specifier (1 byte)
1544          * Filename length (1 byte)
1545          * Filename ("_CONSOLE") (8 bytes)
1546          * Modification date (4 bytes)
1547          * Literal data (arbitrary)
1548          *
1549          * We need at least 16 bytes of data for the packet to even be
1550          * valid.
1551          */
1552         if (max_packet_size < 16) {
1553                 printk(KERN_ERR "Maximum packet size too small\n");
1554                 rc = -EINVAL;
1555                 goto out;
1556         }
1557         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1558                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1559                 rc = -EINVAL;
1560                 goto out;
1561         }
1562         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1563                                           &length_size);
1564         if (rc) {
1565                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1566                 goto out;
1567         }
1568         if (body_size < 14) {
1569                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1570                 rc = -EINVAL;
1571                 goto out;
1572         }
1573         (*packet_size) += length_size;
1574         (*tag_11_contents_size) = (body_size - 14);
1575         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1576                 printk(KERN_ERR "Packet size exceeds max\n");
1577                 rc = -EINVAL;
1578                 goto out;
1579         }
1580         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1581                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1582                        "expected size\n");
1583                 rc = -EINVAL;
1584                 goto out;
1585         }
1586         if (data[(*packet_size)++] != 0x62) {
1587                 printk(KERN_WARNING "Unrecognizable packet\n");
1588                 rc = -EINVAL;
1589                 goto out;
1590         }
1591         if (data[(*packet_size)++] != 0x08) {
1592                 printk(KERN_WARNING "Unrecognizable packet\n");
1593                 rc = -EINVAL;
1594                 goto out;
1595         }
1596         (*packet_size) += 12; /* Ignore filename and modification date */
1597         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1598         (*packet_size) += (*tag_11_contents_size);
1599 out:
1600         if (rc) {
1601                 (*packet_size) = 0;
1602                 (*tag_11_contents_size) = 0;
1603         }
1604         return rc;
1605 }
1606
1607 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1608                                       struct ecryptfs_auth_tok **auth_tok,
1609                                       char *sig)
1610 {
1611         int rc = 0;
1612
1613         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1614         if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1615                 (*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1616                 if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1617                         printk(KERN_ERR "Could not find key with description: [%s]\n",
1618                               sig);
1619                         rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1620                         (*auth_tok_key) = NULL;
1621                         goto out;
1622                 }
1623         }
1624         down_write(&(*auth_tok_key)->sem);
1625         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1626         if (rc) {
1627                 up_write(&(*auth_tok_key)->sem);
1628                 key_put(*auth_tok_key);
1629                 (*auth_tok_key) = NULL;
1630                 goto out;
1631         }
1632 out:
1633         return rc;
1634 }
1635
1636 /**
1637  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1638  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1639  * @crypt_stat: The cryptographic context
1640  *
1641  * Returns zero on success; non-zero error otherwise
1642  */
1643 static int
1644 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1645                                          struct ecryptfs_crypt_stat *crypt_stat)
1646 {
1647         struct scatterlist dst_sg[2];
1648         struct scatterlist src_sg[2];
1649         struct mutex *tfm_mutex;
1650         struct crypto_skcipher *tfm;
1651         struct skcipher_request *req = NULL;
1652         int rc = 0;
1653
1654         if (unlikely(ecryptfs_verbosity > 0)) {
1655                 ecryptfs_printk(
1656                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1657                         auth_tok->token.password.session_key_encryption_key_bytes);
1658                 ecryptfs_dump_hex(
1659                         auth_tok->token.password.session_key_encryption_key,
1660                         auth_tok->token.password.session_key_encryption_key_bytes);
1661         }
1662         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
1663                                                         crypt_stat->cipher);
1664         if (unlikely(rc)) {
1665                 printk(KERN_ERR "Internal error whilst attempting to get "
1666                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1667                        crypt_stat->cipher, rc);
1668                 goto out;
1669         }
1670         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1671                                  auth_tok->session_key.encrypted_key_size,
1672                                  src_sg, 2);
1673         if (rc < 1 || rc > 2) {
1674                 printk(KERN_ERR "Internal error whilst attempting to convert "
1675                         "auth_tok->session_key.encrypted_key to scatterlist; "
1676                         "expected rc = 1; got rc = [%d]. "
1677                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1678                         auth_tok->session_key.encrypted_key_size);
1679                 goto out;
1680         }
1681         auth_tok->session_key.decrypted_key_size =
1682                 auth_tok->session_key.encrypted_key_size;
1683         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1684                                  auth_tok->session_key.decrypted_key_size,
1685                                  dst_sg, 2);
1686         if (rc < 1 || rc > 2) {
1687                 printk(KERN_ERR "Internal error whilst attempting to convert "
1688                         "auth_tok->session_key.decrypted_key to scatterlist; "
1689                         "expected rc = 1; got rc = [%d]\n", rc);
1690                 goto out;
1691         }
1692         mutex_lock(tfm_mutex);
1693         req = skcipher_request_alloc(tfm, GFP_KERNEL);
1694         if (!req) {
1695                 mutex_unlock(tfm_mutex);
1696                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1697                        "skcipher_request_alloc for %s\n", __func__,
1698                        crypto_skcipher_driver_name(tfm));
1699                 rc = -ENOMEM;
1700                 goto out;
1701         }
1702
1703         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
1704                                       NULL, NULL);
1705         rc = crypto_skcipher_setkey(
1706                 tfm, auth_tok->token.password.session_key_encryption_key,
1707                 crypt_stat->key_size);
1708         if (unlikely(rc < 0)) {
1709                 mutex_unlock(tfm_mutex);
1710                 printk(KERN_ERR "Error setting key for crypto context\n");
1711                 rc = -EINVAL;
1712                 goto out;
1713         }
1714         skcipher_request_set_crypt(req, src_sg, dst_sg,
1715                                    auth_tok->session_key.encrypted_key_size,
1716                                    NULL);
1717         rc = crypto_skcipher_decrypt(req);
1718         mutex_unlock(tfm_mutex);
1719         if (unlikely(rc)) {
1720                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1721                 goto out;
1722         }
1723         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1724         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1725                auth_tok->session_key.decrypted_key_size);
1726         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1727         if (unlikely(ecryptfs_verbosity > 0)) {
1728                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1729                                 crypt_stat->key_size);
1730                 ecryptfs_dump_hex(crypt_stat->key,
1731                                   crypt_stat->key_size);
1732         }
1733 out:
1734         skcipher_request_free(req);
1735         return rc;
1736 }
1737
1738 /**
1739  * ecryptfs_parse_packet_set
1740  * @crypt_stat: The cryptographic context
1741  * @src: Virtual address of region of memory containing the packets
1742  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1743  *
1744  * Get crypt_stat to have the file's session key if the requisite key
1745  * is available to decrypt the session key.
1746  *
1747  * Returns Zero if a valid authentication token was retrieved and
1748  * processed; negative value for file not encrypted or for error
1749  * conditions.
1750  */
1751 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1752                               unsigned char *src,
1753                               struct dentry *ecryptfs_dentry)
1754 {
1755         size_t i = 0;
1756         size_t found_auth_tok;
1757         size_t next_packet_is_auth_tok_packet;
1758         struct list_head auth_tok_list;
1759         struct ecryptfs_auth_tok *matching_auth_tok;
1760         struct ecryptfs_auth_tok *candidate_auth_tok;
1761         char *candidate_auth_tok_sig;
1762         size_t packet_size;
1763         struct ecryptfs_auth_tok *new_auth_tok;
1764         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1765         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1766         size_t tag_11_contents_size;
1767         size_t tag_11_packet_size;
1768         struct key *auth_tok_key = NULL;
1769         int rc = 0;
1770
1771         INIT_LIST_HEAD(&auth_tok_list);
1772         /* Parse the header to find as many packets as we can; these will be
1773          * added the our &auth_tok_list */
1774         next_packet_is_auth_tok_packet = 1;
1775         while (next_packet_is_auth_tok_packet) {
1776                 size_t max_packet_size = ((PAGE_SIZE - 8) - i);
1777
1778                 switch (src[i]) {
1779                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1780                         rc = parse_tag_3_packet(crypt_stat,
1781                                                 (unsigned char *)&src[i],
1782                                                 &auth_tok_list, &new_auth_tok,
1783                                                 &packet_size, max_packet_size);
1784                         if (rc) {
1785                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1786                                                 "tag 3 packet\n");
1787                                 rc = -EIO;
1788                                 goto out_wipe_list;
1789                         }
1790                         i += packet_size;
1791                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1792                                                  sig_tmp_space,
1793                                                  ECRYPTFS_SIG_SIZE,
1794                                                  &tag_11_contents_size,
1795                                                  &tag_11_packet_size,
1796                                                  max_packet_size);
1797                         if (rc) {
1798                                 ecryptfs_printk(KERN_ERR, "No valid "
1799                                                 "(ecryptfs-specific) literal "
1800                                                 "packet containing "
1801                                                 "authentication token "
1802                                                 "signature found after "
1803                                                 "tag 3 packet\n");
1804                                 rc = -EIO;
1805                                 goto out_wipe_list;
1806                         }
1807                         i += tag_11_packet_size;
1808                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1809                                 ecryptfs_printk(KERN_ERR, "Expected "
1810                                                 "signature of size [%d]; "
1811                                                 "read size [%zd]\n",
1812                                                 ECRYPTFS_SIG_SIZE,
1813                                                 tag_11_contents_size);
1814                                 rc = -EIO;
1815                                 goto out_wipe_list;
1816                         }
1817                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1818                                         sig_tmp_space, tag_11_contents_size);
1819                         new_auth_tok->token.password.signature[
1820                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1821                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1822                         break;
1823                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1824                         rc = parse_tag_1_packet(crypt_stat,
1825                                                 (unsigned char *)&src[i],
1826                                                 &auth_tok_list, &new_auth_tok,
1827                                                 &packet_size, max_packet_size);
1828                         if (rc) {
1829                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1830                                                 "tag 1 packet\n");
1831                                 rc = -EIO;
1832                                 goto out_wipe_list;
1833                         }
1834                         i += packet_size;
1835                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1836                         break;
1837                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1838                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1839                                         "(Tag 11 not allowed by itself)\n");
1840                         rc = -EIO;
1841                         goto out_wipe_list;
1842                 default:
1843                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1844                                         "of the file header; hex value of "
1845                                         "character is [0x%.2x]\n", i, src[i]);
1846                         next_packet_is_auth_tok_packet = 0;
1847                 }
1848         }
1849         if (list_empty(&auth_tok_list)) {
1850                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1851                        "eCryptfs file; this is not supported in this version "
1852                        "of the eCryptfs kernel module\n");
1853                 rc = -EINVAL;
1854                 goto out;
1855         }
1856         /* auth_tok_list contains the set of authentication tokens
1857          * parsed from the metadata. We need to find a matching
1858          * authentication token that has the secret component(s)
1859          * necessary to decrypt the EFEK in the auth_tok parsed from
1860          * the metadata. There may be several potential matches, but
1861          * just one will be sufficient to decrypt to get the FEK. */
1862 find_next_matching_auth_tok:
1863         found_auth_tok = 0;
1864         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1865                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1866                 if (unlikely(ecryptfs_verbosity > 0)) {
1867                         ecryptfs_printk(KERN_DEBUG,
1868                                         "Considering candidate auth tok:\n");
1869                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1870                 }
1871                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1872                                                candidate_auth_tok);
1873                 if (rc) {
1874                         printk(KERN_ERR
1875                                "Unrecognized candidate auth tok type: [%d]\n",
1876                                candidate_auth_tok->token_type);
1877                         rc = -EINVAL;
1878                         goto out_wipe_list;
1879                 }
1880                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1881                                                &matching_auth_tok,
1882                                                crypt_stat->mount_crypt_stat,
1883                                                candidate_auth_tok_sig);
1884                 if (!rc) {
1885                         found_auth_tok = 1;
1886                         goto found_matching_auth_tok;
1887                 }
1888         }
1889         if (!found_auth_tok) {
1890                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1891                                 "authentication token\n");
1892                 rc = -EIO;
1893                 goto out_wipe_list;
1894         }
1895 found_matching_auth_tok:
1896         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1897                 memcpy(&(candidate_auth_tok->token.private_key),
1898                        &(matching_auth_tok->token.private_key),
1899                        sizeof(struct ecryptfs_private_key));
1900                 up_write(&(auth_tok_key->sem));
1901                 key_put(auth_tok_key);
1902                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1903                                                        crypt_stat);
1904         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1905                 memcpy(&(candidate_auth_tok->token.password),
1906                        &(matching_auth_tok->token.password),
1907                        sizeof(struct ecryptfs_password));
1908                 up_write(&(auth_tok_key->sem));
1909                 key_put(auth_tok_key);
1910                 rc = decrypt_passphrase_encrypted_session_key(
1911                         candidate_auth_tok, crypt_stat);
1912         } else {
1913                 up_write(&(auth_tok_key->sem));
1914                 key_put(auth_tok_key);
1915                 rc = -EINVAL;
1916         }
1917         if (rc) {
1918                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1919
1920                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1921                                 "session key for authentication token with sig "
1922                                 "[%.*s]; rc = [%d]. Removing auth tok "
1923                                 "candidate from the list and searching for "
1924                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1925                                 candidate_auth_tok_sig, rc);
1926                 list_for_each_entry_safe(auth_tok_list_item,
1927                                          auth_tok_list_item_tmp,
1928                                          &auth_tok_list, list) {
1929                         if (candidate_auth_tok
1930                             == &auth_tok_list_item->auth_tok) {
1931                                 list_del(&auth_tok_list_item->list);
1932                                 kmem_cache_free(
1933                                         ecryptfs_auth_tok_list_item_cache,
1934                                         auth_tok_list_item);
1935                                 goto find_next_matching_auth_tok;
1936                         }
1937                 }
1938                 BUG();
1939         }
1940         rc = ecryptfs_compute_root_iv(crypt_stat);
1941         if (rc) {
1942                 ecryptfs_printk(KERN_ERR, "Error computing "
1943                                 "the root IV\n");
1944                 goto out_wipe_list;
1945         }
1946         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1947         if (rc) {
1948                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1949                                 "context for cipher [%s]; rc = [%d]\n",
1950                                 crypt_stat->cipher, rc);
1951         }
1952 out_wipe_list:
1953         wipe_auth_tok_list(&auth_tok_list);
1954 out:
1955         return rc;
1956 }
1957
1958 static int
1959 pki_encrypt_session_key(struct key *auth_tok_key,
1960                         struct ecryptfs_auth_tok *auth_tok,
1961                         struct ecryptfs_crypt_stat *crypt_stat,
1962                         struct ecryptfs_key_record *key_rec)
1963 {
1964         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1965         char *payload = NULL;
1966         size_t payload_len = 0;
1967         struct ecryptfs_message *msg;
1968         int rc;
1969
1970         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1971                                  ecryptfs_code_for_cipher_string(
1972                                          crypt_stat->cipher,
1973                                          crypt_stat->key_size),
1974                                  crypt_stat, &payload, &payload_len);
1975         up_write(&(auth_tok_key->sem));
1976         key_put(auth_tok_key);
1977         if (rc) {
1978                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1979                 goto out;
1980         }
1981         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1982         if (rc) {
1983                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1984                                 "ecryptfsd: %d\n", rc);
1985                 goto out;
1986         }
1987         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1988         if (rc) {
1989                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1990                                 "from the user space daemon\n");
1991                 rc = -EIO;
1992                 goto out;
1993         }
1994         rc = parse_tag_67_packet(key_rec, msg);
1995         if (rc)
1996                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
1997         kfree(msg);
1998 out:
1999         kfree(payload);
2000         return rc;
2001 }
2002 /**
2003  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2004  * @dest: Buffer into which to write the packet
2005  * @remaining_bytes: Maximum number of bytes that can be writtn
2006  * @auth_tok_key: The authentication token key to unlock and put when done with
2007  *                @auth_tok
2008  * @auth_tok: The authentication token used for generating the tag 1 packet
2009  * @crypt_stat: The cryptographic context
2010  * @key_rec: The key record struct for the tag 1 packet
2011  * @packet_size: This function will write the number of bytes that end
2012  *               up constituting the packet; set to zero on error
2013  *
2014  * Returns zero on success; non-zero on error.
2015  */
2016 static int
2017 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2018                    struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2019                    struct ecryptfs_crypt_stat *crypt_stat,
2020                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2021 {
2022         size_t i;
2023         size_t encrypted_session_key_valid = 0;
2024         size_t packet_size_length;
2025         size_t max_packet_size;
2026         int rc = 0;
2027
2028         (*packet_size) = 0;
2029         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2030                           ECRYPTFS_SIG_SIZE);
2031         encrypted_session_key_valid = 0;
2032         for (i = 0; i < crypt_stat->key_size; i++)
2033                 encrypted_session_key_valid |=
2034                         auth_tok->session_key.encrypted_key[i];
2035         if (encrypted_session_key_valid) {
2036                 memcpy(key_rec->enc_key,
2037                        auth_tok->session_key.encrypted_key,
2038                        auth_tok->session_key.encrypted_key_size);
2039                 up_write(&(auth_tok_key->sem));
2040                 key_put(auth_tok_key);
2041                 goto encrypted_session_key_set;
2042         }
2043         if (auth_tok->session_key.encrypted_key_size == 0)
2044                 auth_tok->session_key.encrypted_key_size =
2045                         auth_tok->token.private_key.key_size;
2046         rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2047                                      key_rec);
2048         if (rc) {
2049                 printk(KERN_ERR "Failed to encrypt session key via a key "
2050                        "module; rc = [%d]\n", rc);
2051                 goto out;
2052         }
2053         if (ecryptfs_verbosity > 0) {
2054                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2055                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2056         }
2057 encrypted_session_key_set:
2058         /* This format is inspired by OpenPGP; see RFC 2440
2059          * packet tag 1 */
2060         max_packet_size = (1                         /* Tag 1 identifier */
2061                            + 3                       /* Max Tag 1 packet size */
2062                            + 1                       /* Version */
2063                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2064                            + 1                       /* Cipher identifier */
2065                            + key_rec->enc_key_size); /* Encrypted key size */
2066         if (max_packet_size > (*remaining_bytes)) {
2067                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2068                        "need up to [%td] bytes, but there are only [%td] "
2069                        "available\n", max_packet_size, (*remaining_bytes));
2070                 rc = -EINVAL;
2071                 goto out;
2072         }
2073         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2074         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2075                                           (max_packet_size - 4),
2076                                           &packet_size_length);
2077         if (rc) {
2078                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2079                                 "header; cannot generate packet length\n");
2080                 goto out;
2081         }
2082         (*packet_size) += packet_size_length;
2083         dest[(*packet_size)++] = 0x03; /* version 3 */
2084         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2085         (*packet_size) += ECRYPTFS_SIG_SIZE;
2086         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2087         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2088                key_rec->enc_key_size);
2089         (*packet_size) += key_rec->enc_key_size;
2090 out:
2091         if (rc)
2092                 (*packet_size) = 0;
2093         else
2094                 (*remaining_bytes) -= (*packet_size);
2095         return rc;
2096 }
2097
2098 /**
2099  * write_tag_11_packet
2100  * @dest: Target into which Tag 11 packet is to be written
2101  * @remaining_bytes: Maximum packet length
2102  * @contents: Byte array of contents to copy in
2103  * @contents_length: Number of bytes in contents
2104  * @packet_length: Length of the Tag 11 packet written; zero on error
2105  *
2106  * Returns zero on success; non-zero on error.
2107  */
2108 static int
2109 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2110                     size_t contents_length, size_t *packet_length)
2111 {
2112         size_t packet_size_length;
2113         size_t max_packet_size;
2114         int rc = 0;
2115
2116         (*packet_length) = 0;
2117         /* This format is inspired by OpenPGP; see RFC 2440
2118          * packet tag 11 */
2119         max_packet_size = (1                   /* Tag 11 identifier */
2120                            + 3                 /* Max Tag 11 packet size */
2121                            + 1                 /* Binary format specifier */
2122                            + 1                 /* Filename length */
2123                            + 8                 /* Filename ("_CONSOLE") */
2124                            + 4                 /* Modification date */
2125                            + contents_length); /* Literal data */
2126         if (max_packet_size > (*remaining_bytes)) {
2127                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2128                        "need up to [%td] bytes, but there are only [%td] "
2129                        "available\n", max_packet_size, (*remaining_bytes));
2130                 rc = -EINVAL;
2131                 goto out;
2132         }
2133         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2134         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2135                                           (max_packet_size - 4),
2136                                           &packet_size_length);
2137         if (rc) {
2138                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2139                        "generate packet length. rc = [%d]\n", rc);
2140                 goto out;
2141         }
2142         (*packet_length) += packet_size_length;
2143         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2144         dest[(*packet_length)++] = 8;
2145         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2146         (*packet_length) += 8;
2147         memset(&dest[(*packet_length)], 0x00, 4);
2148         (*packet_length) += 4;
2149         memcpy(&dest[(*packet_length)], contents, contents_length);
2150         (*packet_length) += contents_length;
2151  out:
2152         if (rc)
2153                 (*packet_length) = 0;
2154         else
2155                 (*remaining_bytes) -= (*packet_length);
2156         return rc;
2157 }
2158
2159 /**
2160  * write_tag_3_packet
2161  * @dest: Buffer into which to write the packet
2162  * @remaining_bytes: Maximum number of bytes that can be written
2163  * @auth_tok: Authentication token
2164  * @crypt_stat: The cryptographic context
2165  * @key_rec: encrypted key
2166  * @packet_size: This function will write the number of bytes that end
2167  *               up constituting the packet; set to zero on error
2168  *
2169  * Returns zero on success; non-zero on error.
2170  */
2171 static int
2172 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2173                    struct ecryptfs_auth_tok *auth_tok,
2174                    struct ecryptfs_crypt_stat *crypt_stat,
2175                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2176 {
2177         size_t i;
2178         size_t encrypted_session_key_valid = 0;
2179         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2180         struct scatterlist dst_sg[2];
2181         struct scatterlist src_sg[2];
2182         struct mutex *tfm_mutex = NULL;
2183         u8 cipher_code;
2184         size_t packet_size_length;
2185         size_t max_packet_size;
2186         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2187                 crypt_stat->mount_crypt_stat;
2188         struct crypto_skcipher *tfm;
2189         struct skcipher_request *req;
2190         int rc = 0;
2191
2192         (*packet_size) = 0;
2193         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2194                           ECRYPTFS_SIG_SIZE);
2195         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2196                                                         crypt_stat->cipher);
2197         if (unlikely(rc)) {
2198                 printk(KERN_ERR "Internal error whilst attempting to get "
2199                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2200                        crypt_stat->cipher, rc);
2201                 goto out;
2202         }
2203         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2204                 printk(KERN_WARNING "No key size specified at mount; "
2205                        "defaulting to [%d]\n",
2206                        crypto_skcipher_default_keysize(tfm));
2207                 mount_crypt_stat->global_default_cipher_key_size =
2208                         crypto_skcipher_default_keysize(tfm);
2209         }
2210         if (crypt_stat->key_size == 0)
2211                 crypt_stat->key_size =
2212                         mount_crypt_stat->global_default_cipher_key_size;
2213         if (auth_tok->session_key.encrypted_key_size == 0)
2214                 auth_tok->session_key.encrypted_key_size =
2215                         crypt_stat->key_size;
2216         if (crypt_stat->key_size == 24
2217             && strcmp("aes", crypt_stat->cipher) == 0) {
2218                 memset((crypt_stat->key + 24), 0, 8);
2219                 auth_tok->session_key.encrypted_key_size = 32;
2220         } else
2221                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2222         key_rec->enc_key_size =
2223                 auth_tok->session_key.encrypted_key_size;
2224         encrypted_session_key_valid = 0;
2225         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2226                 encrypted_session_key_valid |=
2227                         auth_tok->session_key.encrypted_key[i];
2228         if (encrypted_session_key_valid) {
2229                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2230                                 "using auth_tok->session_key.encrypted_key, "
2231                                 "where key_rec->enc_key_size = [%zd]\n",
2232                                 key_rec->enc_key_size);
2233                 memcpy(key_rec->enc_key,
2234                        auth_tok->session_key.encrypted_key,
2235                        key_rec->enc_key_size);
2236                 goto encrypted_session_key_set;
2237         }
2238         if (auth_tok->token.password.flags &
2239             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2240                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2241                                 "session key encryption key of size [%d]\n",
2242                                 auth_tok->token.password.
2243                                 session_key_encryption_key_bytes);
2244                 memcpy(session_key_encryption_key,
2245                        auth_tok->token.password.session_key_encryption_key,
2246                        crypt_stat->key_size);
2247                 ecryptfs_printk(KERN_DEBUG,
2248                                 "Cached session key encryption key:\n");
2249                 if (ecryptfs_verbosity > 0)
2250                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2251         }
2252         if (unlikely(ecryptfs_verbosity > 0)) {
2253                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2254                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2255         }
2256         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2257                                  src_sg, 2);
2258         if (rc < 1 || rc > 2) {
2259                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2260                                 "for crypt_stat session key; expected rc = 1; "
2261                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2262                                 rc, key_rec->enc_key_size);
2263                 rc = -ENOMEM;
2264                 goto out;
2265         }
2266         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2267                                  dst_sg, 2);
2268         if (rc < 1 || rc > 2) {
2269                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2270                                 "for crypt_stat encrypted session key; "
2271                                 "expected rc = 1; got rc = [%d]. "
2272                                 "key_rec->enc_key_size = [%zd]\n", rc,
2273                                 key_rec->enc_key_size);
2274                 rc = -ENOMEM;
2275                 goto out;
2276         }
2277         mutex_lock(tfm_mutex);
2278         rc = crypto_skcipher_setkey(tfm, session_key_encryption_key,
2279                                     crypt_stat->key_size);
2280         if (rc < 0) {
2281                 mutex_unlock(tfm_mutex);
2282                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2283                                 "context; rc = [%d]\n", rc);
2284                 goto out;
2285         }
2286
2287         req = skcipher_request_alloc(tfm, GFP_KERNEL);
2288         if (!req) {
2289                 mutex_unlock(tfm_mutex);
2290                 ecryptfs_printk(KERN_ERR, "Out of kernel memory whilst "
2291                                 "attempting to skcipher_request_alloc for "
2292                                 "%s\n", crypto_skcipher_driver_name(tfm));
2293                 rc = -ENOMEM;
2294                 goto out;
2295         }
2296
2297         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
2298                                       NULL, NULL);
2299
2300         rc = 0;
2301         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2302                         crypt_stat->key_size);
2303         skcipher_request_set_crypt(req, src_sg, dst_sg,
2304                                    (*key_rec).enc_key_size, NULL);
2305         rc = crypto_skcipher_encrypt(req);
2306         mutex_unlock(tfm_mutex);
2307         skcipher_request_free(req);
2308         if (rc) {
2309                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2310                 goto out;
2311         }
2312         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2313         if (ecryptfs_verbosity > 0) {
2314                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2315                                 key_rec->enc_key_size);
2316                 ecryptfs_dump_hex(key_rec->enc_key,
2317                                   key_rec->enc_key_size);
2318         }
2319 encrypted_session_key_set:
2320         /* This format is inspired by OpenPGP; see RFC 2440
2321          * packet tag 3 */
2322         max_packet_size = (1                         /* Tag 3 identifier */
2323                            + 3                       /* Max Tag 3 packet size */
2324                            + 1                       /* Version */
2325                            + 1                       /* Cipher code */
2326                            + 1                       /* S2K specifier */
2327                            + 1                       /* Hash identifier */
2328                            + ECRYPTFS_SALT_SIZE      /* Salt */
2329                            + 1                       /* Hash iterations */
2330                            + key_rec->enc_key_size); /* Encrypted key size */
2331         if (max_packet_size > (*remaining_bytes)) {
2332                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2333                        "there are only [%td] available\n", max_packet_size,
2334                        (*remaining_bytes));
2335                 rc = -EINVAL;
2336                 goto out;
2337         }
2338         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2339         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2340          * to get the number of octets in the actual Tag 3 packet */
2341         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2342                                           (max_packet_size - 4),
2343                                           &packet_size_length);
2344         if (rc) {
2345                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2346                        "generate packet length. rc = [%d]\n", rc);
2347                 goto out;
2348         }
2349         (*packet_size) += packet_size_length;
2350         dest[(*packet_size)++] = 0x04; /* version 4 */
2351         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2352          * specified with strings */
2353         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2354                                                       crypt_stat->key_size);
2355         if (cipher_code == 0) {
2356                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2357                                 "cipher [%s]\n", crypt_stat->cipher);
2358                 rc = -EINVAL;
2359                 goto out;
2360         }
2361         dest[(*packet_size)++] = cipher_code;
2362         dest[(*packet_size)++] = 0x03;  /* S2K */
2363         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2364         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2365                ECRYPTFS_SALT_SIZE);
2366         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2367         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2368         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2369                key_rec->enc_key_size);
2370         (*packet_size) += key_rec->enc_key_size;
2371 out:
2372         if (rc)
2373                 (*packet_size) = 0;
2374         else
2375                 (*remaining_bytes) -= (*packet_size);
2376         return rc;
2377 }
2378
2379 struct kmem_cache *ecryptfs_key_record_cache;
2380
2381 /**
2382  * ecryptfs_generate_key_packet_set
2383  * @dest_base: Virtual address from which to write the key record set
2384  * @crypt_stat: The cryptographic context from which the
2385  *              authentication tokens will be retrieved
2386  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2387  *                   for the global parameters
2388  * @len: The amount written
2389  * @max: The maximum amount of data allowed to be written
2390  *
2391  * Generates a key packet set and writes it to the virtual address
2392  * passed in.
2393  *
2394  * Returns zero on success; non-zero on error.
2395  */
2396 int
2397 ecryptfs_generate_key_packet_set(char *dest_base,
2398                                  struct ecryptfs_crypt_stat *crypt_stat,
2399                                  struct dentry *ecryptfs_dentry, size_t *len,
2400                                  size_t max)
2401 {
2402         struct ecryptfs_auth_tok *auth_tok;
2403         struct key *auth_tok_key = NULL;
2404         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2405                 &ecryptfs_superblock_to_private(
2406                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2407         size_t written;
2408         struct ecryptfs_key_record *key_rec;
2409         struct ecryptfs_key_sig *key_sig;
2410         int rc = 0;
2411
2412         (*len) = 0;
2413         mutex_lock(&crypt_stat->keysig_list_mutex);
2414         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2415         if (!key_rec) {
2416                 rc = -ENOMEM;
2417                 goto out;
2418         }
2419         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2420                             crypt_stat_list) {
2421                 memset(key_rec, 0, sizeof(*key_rec));
2422                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2423                                                            &auth_tok,
2424                                                            mount_crypt_stat,
2425                                                            key_sig->keysig);
2426                 if (rc) {
2427                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2428                                "sig = [%s]\n", key_sig->keysig);
2429                         rc = process_find_global_auth_tok_for_sig_err(rc);
2430                         goto out_free;
2431                 }
2432                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2433                         rc = write_tag_3_packet((dest_base + (*len)),
2434                                                 &max, auth_tok,
2435                                                 crypt_stat, key_rec,
2436                                                 &written);
2437                         up_write(&(auth_tok_key->sem));
2438                         key_put(auth_tok_key);
2439                         if (rc) {
2440                                 ecryptfs_printk(KERN_WARNING, "Error "
2441                                                 "writing tag 3 packet\n");
2442                                 goto out_free;
2443                         }
2444                         (*len) += written;
2445                         /* Write auth tok signature packet */
2446                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2447                                                  key_rec->sig,
2448                                                  ECRYPTFS_SIG_SIZE, &written);
2449                         if (rc) {
2450                                 ecryptfs_printk(KERN_ERR, "Error writing "
2451                                                 "auth tok signature packet\n");
2452                                 goto out_free;
2453                         }
2454                         (*len) += written;
2455                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2456                         rc = write_tag_1_packet(dest_base + (*len), &max,
2457                                                 auth_tok_key, auth_tok,
2458                                                 crypt_stat, key_rec, &written);
2459                         if (rc) {
2460                                 ecryptfs_printk(KERN_WARNING, "Error "
2461                                                 "writing tag 1 packet\n");
2462                                 goto out_free;
2463                         }
2464                         (*len) += written;
2465                 } else {
2466                         up_write(&(auth_tok_key->sem));
2467                         key_put(auth_tok_key);
2468                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2469                                         "authentication token type\n");
2470                         rc = -EINVAL;
2471                         goto out_free;
2472                 }
2473         }
2474         if (likely(max > 0)) {
2475                 dest_base[(*len)] = 0x00;
2476         } else {
2477                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2478                 rc = -EIO;
2479         }
2480 out_free:
2481         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2482 out:
2483         if (rc)
2484                 (*len) = 0;
2485         mutex_unlock(&crypt_stat->keysig_list_mutex);
2486         return rc;
2487 }
2488
2489 struct kmem_cache *ecryptfs_key_sig_cache;
2490
2491 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2492 {
2493         struct ecryptfs_key_sig *new_key_sig;
2494
2495         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2496         if (!new_key_sig)
2497                 return -ENOMEM;
2498
2499         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2500         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2501         /* Caller must hold keysig_list_mutex */
2502         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2503
2504         return 0;
2505 }
2506
2507 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2508
2509 int
2510 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2511                              char *sig, u32 global_auth_tok_flags)
2512 {
2513         struct ecryptfs_global_auth_tok *new_auth_tok;
2514
2515         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2516                                         GFP_KERNEL);
2517         if (!new_auth_tok)
2518                 return -ENOMEM;
2519
2520         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2521         new_auth_tok->flags = global_auth_tok_flags;
2522         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2523         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2524         list_add(&new_auth_tok->mount_crypt_stat_list,
2525                  &mount_crypt_stat->global_auth_tok_list);
2526         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2527         return 0;
2528 }
2529