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 <mhalcrow@us.ibm.com>
  10  *              Michael C. Thompson <mcthomps@us.ibm.com>
  11  *              Trevor S. Highland <trevor.highland@gmail.com>
  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_key: key containing the authentication token
 540  * @auth_tok: Set to the matching auth_tok; NULL if not found
 541  * @mount_crypt_stat: inode crypt_stat crypto context
 542  * @sig: Sig of auth_tok to find
 543  *
 544  * For now, this function simply looks at the registered auth_tok's
 545  * linked off the mount_crypt_stat, so all the auth_toks that can be
 546  * used must be registered at mount time. This function could
 547  * potentially try a lot harder to find auth_tok's (e.g., by calling
 548  * out to ecryptfsd to dynamically retrieve an auth_tok object) so
 549  * that static registration of auth_tok's will no longer be necessary.
 550  *
 551  * Returns zero on no error; non-zero on error
 552  */
 553 static int
 554 ecryptfs_find_auth_tok_for_sig(
 555         struct key **auth_tok_key,
 556         struct ecryptfs_auth_tok **auth_tok,
 557         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 558         char *sig)
 559 {
 560         int rc = 0;
 561
 562         rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
 563                                                    mount_crypt_stat, sig);
 564         if (rc == -ENOENT) {
 565                 /* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
 566                  * mount_crypt_stat structure, we prevent to use auth toks that
 567                  * are not inserted through the ecryptfs_add_global_auth_tok
 568                  * function.
 569                  */
 570                 if (mount_crypt_stat->flags
 571                                 & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 572                         return -EINVAL;
 573
 574                 rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
 575                                                        sig);
 576         }
 577         return rc;
 578 }
 579
 580 /*
 581  * write_tag_70_packet can gobble a lot of stack space. We stuff most
 582  * of the function's parameters in a kmalloc'd struct to help reduce
 583  * eCryptfs' overall stack usage.
 584  */
 585 struct ecryptfs_write_tag_70_packet_silly_stack {
 586         u8 cipher_code;
 587         size_t max_packet_size;
 588         size_t packet_size_len;
 589         size_t block_aligned_filename_size;
 590         size_t block_size;
 591         size_t i;
 592         size_t j;
 593         size_t num_rand_bytes;
 594         struct mutex *tfm_mutex;
 595         char *block_aligned_filename;
 596         struct ecryptfs_auth_tok *auth_tok;
 597         struct scatterlist src_sg[2];
 598         struct scatterlist dst_sg[2];
 599         struct crypto_skcipher *skcipher_tfm;
 600         struct skcipher_request *skcipher_req;
 601         char iv[ECRYPTFS_MAX_IV_BYTES];
 602         char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 603         char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 604         struct crypto_shash *hash_tfm;
 605         struct shash_desc *hash_desc;
 606 };
 607
 608 /*
 609  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
 610  * @filename: NULL-terminated filename string
 611  *
 612  * This is the simplest mechanism for achieving filename encryption in
 613  * eCryptfs. It encrypts the given filename with the mount-wide
 614  * filename encryption key (FNEK) and stores it in a packet to @dest,
 615  * which the callee will encode and write directly into the dentry
 616  * name.
 617  */
 618 int
 619 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 620                              size_t *packet_size,
 621                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 622                              char *filename, size_t filename_size)
 623 {
 624         struct ecryptfs_write_tag_70_packet_silly_stack *s;
 625         struct key *auth_tok_key = NULL;
 626         int rc = 0;
 627
 628         s = kzalloc(sizeof(*s), GFP_KERNEL);
 629         if (!s)
 630                 return -ENOMEM;
 631
 632         (*packet_size) = 0;
 633         rc = ecryptfs_find_auth_tok_for_sig(
 634                 &auth_tok_key,
 635                 &s->auth_tok, mount_crypt_stat,
 636                 mount_crypt_stat->global_default_fnek_sig);
 637         if (rc) {
 638                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 639                        "fnek sig [%s]; rc = [%d]\n", __func__,
 640                        mount_crypt_stat->global_default_fnek_sig, rc);
 641                 goto out;
 642         }
 643         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
 644                 &s->skcipher_tfm,
 645                 &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
 646         if (unlikely(rc)) {
 647                 printk(KERN_ERR "Internal error whilst attempting to get "
 648                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 649                        mount_crypt_stat->global_default_fn_cipher_name, rc);
 650                 goto out;
 651         }
 652         mutex_lock(s->tfm_mutex);
 653         s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
 654         /* Plus one for the \0 separator between the random prefix
 655          * and the plaintext filename */
 656         s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
 657         s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
 658         if ((s->block_aligned_filename_size % s->block_size) != 0) {
 659                 s->num_rand_bytes += (s->block_size
 660                                       - (s->block_aligned_filename_size
 661                                          % s->block_size));
 662                 s->block_aligned_filename_size = (s->num_rand_bytes
 663                                                   + filename_size);
 664         }
 665         /* Octet 0: Tag 70 identifier
 666          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 667          *              and block-aligned encrypted filename size)
 668          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 669          * Octet N2-N3: Cipher identifier (1 octet)
 670          * Octets N3-N4: Block-aligned encrypted filename
 671          *  - Consists of a minimum number of random characters, a \0
 672          *    separator, and then the filename */
 673         s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
 674                               + s->block_aligned_filename_size);
 675         if (!dest) {
 676                 (*packet_size) = s->max_packet_size;
 677                 goto out_unlock;
 678         }
 679         if (s->max_packet_size > (*remaining_bytes)) {
 680                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
 681                        "[%zd] available\n", __func__, s->max_packet_size,
 682                        (*remaining_bytes));
 683                 rc = -EINVAL;
 684                 goto out_unlock;
 685         }
 686
 687         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
 688         if (!s->skcipher_req) {
 689                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
 690                        "skcipher_request_alloc for %s\n", __func__,
 691                        crypto_skcipher_driver_name(s->skcipher_tfm));
 692                 rc = -ENOMEM;
 693                 goto out_unlock;
 694         }
 695
 696         skcipher_request_set_callback(s->skcipher_req,
 697                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 698
 699         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
 700                                             GFP_KERNEL);
 701         if (!s->block_aligned_filename) {
 702                 rc = -ENOMEM;
 703                 goto out_unlock;
 704         }
 705         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
 706         rc = ecryptfs_write_packet_length(&dest[s->i],
 707                                           (ECRYPTFS_SIG_SIZE
 708                                            + 1 /* Cipher code */
 709                                            + s->block_aligned_filename_size),
 710                                           &s->packet_size_len);
 711         if (rc) {
 712                 printk(KERN_ERR "%s: Error generating tag 70 packet "
 713                        "header; cannot generate packet length; rc = [%d]\n",
 714                        __func__, rc);
 715                 goto out_free_unlock;
 716         }
 717         s->i += s->packet_size_len;
 718         ecryptfs_from_hex(&dest[s->i],
 719                           mount_crypt_stat->global_default_fnek_sig,
 720                           ECRYPTFS_SIG_SIZE);
 721         s->i += ECRYPTFS_SIG_SIZE;
 722         s->cipher_code = ecryptfs_code_for_cipher_string(
 723                 mount_crypt_stat->global_default_fn_cipher_name,
 724                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 725         if (s->cipher_code == 0) {
 726                 printk(KERN_WARNING "%s: Unable to generate code for "
 727                        "cipher [%s] with key bytes [%zd]\n", __func__,
 728                        mount_crypt_stat->global_default_fn_cipher_name,
 729                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 730                 rc = -EINVAL;
 731                 goto out_free_unlock;
 732         }
 733         dest[s->i++] = s->cipher_code;
 734         /* TODO: Support other key modules than passphrase for
 735          * filename encryption */
 736         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
 737                 rc = -EOPNOTSUPP;
 738                 printk(KERN_INFO "%s: Filename encryption only supports "
 739                        "password tokens\n", __func__);
 740                 goto out_free_unlock;
 741         }
 742         s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
 743         if (IS_ERR(s->hash_tfm)) {
 744                         rc = PTR_ERR(s->hash_tfm);
 745                         printk(KERN_ERR "%s: Error attempting to "
 746                                "allocate hash crypto context; rc = [%d]\n",
 747                                __func__, rc);
 748                         goto out_free_unlock;
 749         }
 750
 751         s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
 752                                crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
 753         if (!s->hash_desc) {
 754                 rc = -ENOMEM;
 755                 goto out_release_free_unlock;
 756         }
 757
 758         s->hash_desc->tfm = s->hash_tfm;
 759
 760         rc = crypto_shash_digest(s->hash_desc,
 761                                  (u8 *)s->auth_tok->token.password.session_key_encryption_key,
 762                                  s->auth_tok->token.password.session_key_encryption_key_bytes,
 763                                  s->hash);
 764         if (rc) {
 765                 printk(KERN_ERR
 766                        "%s: Error computing crypto hash; rc = [%d]\n",
 767                        __func__, rc);
 768                 goto out_release_free_unlock;
 769         }
 770         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
 771                 s->block_aligned_filename[s->j] =
 772                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
 773                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
 774                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
 775                         rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
 776                                                 ECRYPTFS_TAG_70_DIGEST_SIZE,
 777                                                 s->tmp_hash);
 778                         if (rc) {
 779                                 printk(KERN_ERR
 780                                        "%s: Error computing crypto hash; "
 781                                        "rc = [%d]\n", __func__, rc);
 782                                 goto out_release_free_unlock;
 783                         }
 784                         memcpy(s->hash, s->tmp_hash,
 785                                ECRYPTFS_TAG_70_DIGEST_SIZE);
 786                 }
 787                 if (s->block_aligned_filename[s->j] == '\0')
 788                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
 789         }
 790         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 791                filename_size);
 792         rc = virt_to_scatterlist(s->block_aligned_filename,
 793                                  s->block_aligned_filename_size, s->src_sg, 2);
 794         if (rc < 1) {
 795                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 796                        "convert filename memory to scatterlist; rc = [%d]. "
 797                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 798                        s->block_aligned_filename_size);
 799                 goto out_release_free_unlock;
 800         }
 801         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
 802                                  s->dst_sg, 2);
 803         if (rc < 1) {
 804                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 805                        "convert encrypted filename memory to scatterlist; "
 806                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 807                        __func__, rc, s->block_aligned_filename_size);
 808                 goto out_release_free_unlock;
 809         }
 810         /* The characters in the first block effectively do the job
 811          * of the IV here, so we just use 0's for the IV. Note the
 812          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
 813          * >= ECRYPTFS_MAX_IV_BYTES. */
 814         rc = crypto_skcipher_setkey(
 815                 s->skcipher_tfm,
 816                 s->auth_tok->token.password.session_key_encryption_key,
 817                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 818         if (rc < 0) {
 819                 printk(KERN_ERR "%s: Error setting key for crypto context; "
 820                        "rc = [%d]. s->auth_tok->token.password.session_key_"
 821                        "encryption_key = [0x%p]; mount_crypt_stat->"
 822                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
 823                        rc,
 824                        s->auth_tok->token.password.session_key_encryption_key,
 825                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 826                 goto out_release_free_unlock;
 827         }
 828         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
 829                                    s->block_aligned_filename_size, s->iv);
 830         rc = crypto_skcipher_encrypt(s->skcipher_req);
 831         if (rc) {
 832                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
 833                        "rc = [%d]\n", __func__, rc);
 834                 goto out_release_free_unlock;
 835         }
 836         s->i += s->block_aligned_filename_size;
 837         (*packet_size) = s->i;
 838         (*remaining_bytes) -= (*packet_size);
 839 out_release_free_unlock:
 840         crypto_free_shash(s->hash_tfm);
 841 out_free_unlock:
 842         kfree_sensitive(s->block_aligned_filename);
 843 out_unlock:
 844         mutex_unlock(s->tfm_mutex);
 845 out:
 846         if (auth_tok_key) {
 847                 up_write(&(auth_tok_key->sem));
 848                 key_put(auth_tok_key);
 849         }
 850         skcipher_request_free(s->skcipher_req);
 851         kfree_sensitive(s->hash_desc);
 852         kfree(s);
 853         return rc;
 854 }
 855
 856 struct ecryptfs_parse_tag_70_packet_silly_stack {
 857         u8 cipher_code;
 858         size_t max_packet_size;
 859         size_t packet_size_len;
 860         size_t parsed_tag_70_packet_size;
 861         size_t block_aligned_filename_size;
 862         size_t block_size;
 863         size_t i;
 864         struct mutex *tfm_mutex;
 865         char *decrypted_filename;
 866         struct ecryptfs_auth_tok *auth_tok;
 867         struct scatterlist src_sg[2];
 868         struct scatterlist dst_sg[2];
 869         struct crypto_skcipher *skcipher_tfm;
 870         struct skcipher_request *skcipher_req;
 871         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 872         char iv[ECRYPTFS_MAX_IV_BYTES];
 873         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
 874 };
 875
 876 /**
 877  * ecryptfs_parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 878  * @filename: This function kmalloc's the memory for the filename
 879  * @filename_size: This function sets this to the amount of memory
 880  *                 kmalloc'd for the filename
 881  * @packet_size: This function sets this to the the number of octets
 882  *               in the packet parsed
 883  * @mount_crypt_stat: The mount-wide cryptographic context
 884  * @data: The memory location containing the start of the tag 70
 885  *        packet
 886  * @max_packet_size: The maximum legal size of the packet to be parsed
 887  *                   from @data
 888  *
 889  * Returns zero on success; non-zero otherwise
 890  */
 891 int
 892 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 893                              size_t *packet_size,
 894                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 895                              char *data, size_t max_packet_size)
 896 {
 897         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
 898         struct key *auth_tok_key = NULL;
 899         int rc = 0;
 900
 901         (*packet_size) = 0;
 902         (*filename_size) = 0;
 903         (*filename) = NULL;
 904         s = kzalloc(sizeof(*s), GFP_KERNEL);
 905         if (!s)
 906                 return -ENOMEM;
 907
 908         if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
 909                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
 910                        "at least [%d]\n", __func__, max_packet_size,
 911                        ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
 912                 rc = -EINVAL;
 913                 goto out;
 914         }
 915         /* Octet 0: Tag 70 identifier
 916          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 917          *              and block-aligned encrypted filename size)
 918          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 919          * Octet N2-N3: Cipher identifier (1 octet)
 920          * Octets N3-N4: Block-aligned encrypted filename
 921          *  - Consists of a minimum number of random numbers, a \0
 922          *    separator, and then the filename */
 923         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
 924                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
 925                        "tag [0x%.2x]\n", __func__,
 926                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
 927                 rc = -EINVAL;
 928                 goto out;
 929         }
 930         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
 931                                           &s->parsed_tag_70_packet_size,
 932                                           &s->packet_size_len);
 933         if (rc) {
 934                 printk(KERN_WARNING "%s: Error parsing packet length; "
 935                        "rc = [%d]\n", __func__, rc);
 936                 goto out;
 937         }
 938         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
 939                                           - ECRYPTFS_SIG_SIZE - 1);
 940         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
 941             > max_packet_size) {
 942                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
 943                        "size is [%zd]\n", __func__, max_packet_size,
 944                        (1 + s->packet_size_len + 1
 945                         + s->block_aligned_filename_size));
 946                 rc = -EINVAL;
 947                 goto out;
 948         }
 949         (*packet_size) += s->packet_size_len;
 950         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
 951                         ECRYPTFS_SIG_SIZE);
 952         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 953         (*packet_size) += ECRYPTFS_SIG_SIZE;
 954         s->cipher_code = data[(*packet_size)++];
 955         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
 956         if (rc) {
 957                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
 958                        __func__, s->cipher_code);
 959                 goto out;
 960         }
 961         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
 962                                             &s->auth_tok, mount_crypt_stat,
 963                                             s->fnek_sig_hex);
 964         if (rc) {
 965                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 966                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
 967                        rc);
 968                 goto out;
 969         }
 970         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
 971                                                         &s->tfm_mutex,
 972                                                         s->cipher_string);
 973         if (unlikely(rc)) {
 974                 printk(KERN_ERR "Internal error whilst attempting to get "
 975                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 976                        s->cipher_string, rc);
 977                 goto out;
 978         }
 979         mutex_lock(s->tfm_mutex);
 980         rc = virt_to_scatterlist(&data[(*packet_size)],
 981                                  s->block_aligned_filename_size, s->src_sg, 2);
 982         if (rc < 1) {
 983                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 984                        "convert encrypted filename memory to scatterlist; "
 985                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 986                        __func__, rc, s->block_aligned_filename_size);
 987                 goto out_unlock;
 988         }
 989         (*packet_size) += s->block_aligned_filename_size;
 990         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
 991                                         GFP_KERNEL);
 992         if (!s->decrypted_filename) {
 993                 rc = -ENOMEM;
 994                 goto out_unlock;
 995         }
 996         rc = virt_to_scatterlist(s->decrypted_filename,
 997                                  s->block_aligned_filename_size, s->dst_sg, 2);
 998         if (rc < 1) {
 999                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1000                        "convert decrypted filename memory to scatterlist; "
1001                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1002                        __func__, rc, s->block_aligned_filename_size);
1003                 goto out_free_unlock;
1004         }
1005
1006         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
1007         if (!s->skcipher_req) {
1008                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1009                        "skcipher_request_alloc for %s\n", __func__,
1010                        crypto_skcipher_driver_name(s->skcipher_tfm));
1011                 rc = -ENOMEM;
1012                 goto out_free_unlock;
1013         }
1014
1015         skcipher_request_set_callback(s->skcipher_req,
1016                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
1017
1018         /* The characters in the first block effectively do the job of
1019          * the IV here, so we just use 0's for the IV. Note the
1020          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1021          * >= ECRYPTFS_MAX_IV_BYTES. */
1022         /* TODO: Support other key modules than passphrase for
1023          * filename encryption */
1024         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1025                 rc = -EOPNOTSUPP;
1026                 printk(KERN_INFO "%s: Filename encryption only supports "
1027                        "password tokens\n", __func__);
1028                 goto out_free_unlock;
1029         }
1030         rc = crypto_skcipher_setkey(
1031                 s->skcipher_tfm,
1032                 s->auth_tok->token.password.session_key_encryption_key,
1033                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1034         if (rc < 0) {
1035                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1036                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1037                        "encryption_key = [0x%p]; mount_crypt_stat->"
1038                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1039                        rc,
1040                        s->auth_tok->token.password.session_key_encryption_key,
1041                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1042                 goto out_free_unlock;
1043         }
1044         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
1045                                    s->block_aligned_filename_size, s->iv);
1046         rc = crypto_skcipher_decrypt(s->skcipher_req);
1047         if (rc) {
1048                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1049                        "rc = [%d]\n", __func__, rc);
1050                 goto out_free_unlock;
1051         }
1052
1053         while (s->i < s->block_aligned_filename_size &&
1054                s->decrypted_filename[s->i] != '\0')
1055                 s->i++;
1056         if (s->i == s->block_aligned_filename_size) {
1057                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1058                        "find valid separator between random characters and "
1059                        "the filename\n", __func__);
1060                 rc = -EINVAL;
1061                 goto out_free_unlock;
1062         }
1063         s->i++;
1064         (*filename_size) = (s->block_aligned_filename_size - s->i);
1065         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1066                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1067                        "invalid\n", __func__, (*filename_size));
1068                 rc = -EINVAL;
1069                 goto out_free_unlock;
1070         }
1071         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1072         if (!(*filename)) {
1073                 rc = -ENOMEM;
1074                 goto out_free_unlock;
1075         }
1076         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1077         (*filename)[(*filename_size)] = '\0';
1078 out_free_unlock:
1079         kfree(s->decrypted_filename);
1080 out_unlock:
1081         mutex_unlock(s->tfm_mutex);
1082 out:
1083         if (rc) {
1084                 (*packet_size) = 0;
1085                 (*filename_size) = 0;
1086                 (*filename) = NULL;
1087         }
1088         if (auth_tok_key) {
1089                 up_write(&(auth_tok_key->sem));
1090                 key_put(auth_tok_key);
1091         }
1092         skcipher_request_free(s->skcipher_req);
1093         kfree(s);
1094         return rc;
1095 }
1096
1097 static int
1098 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1099 {
1100         int rc = 0;
1101
1102         (*sig) = NULL;
1103         switch (auth_tok->token_type) {
1104         case ECRYPTFS_PASSWORD:
1105                 (*sig) = auth_tok->token.password.signature;
1106                 break;
1107         case ECRYPTFS_PRIVATE_KEY:
1108                 (*sig) = auth_tok->token.private_key.signature;
1109                 break;
1110         default:
1111                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1112                        auth_tok->token_type);
1113                 rc = -EINVAL;
1114         }
1115         return rc;
1116 }
1117
1118 /**
1119  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1120  * @auth_tok: The key authentication token used to decrypt the session key
1121  * @crypt_stat: The cryptographic context
1122  *
1123  * Returns zero on success; non-zero error otherwise.
1124  */
1125 static int
1126 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1127                                   struct ecryptfs_crypt_stat *crypt_stat)
1128 {
1129         u8 cipher_code = 0;
1130         struct ecryptfs_msg_ctx *msg_ctx;
1131         struct ecryptfs_message *msg = NULL;
1132         char *auth_tok_sig;
1133         char *payload = NULL;
1134         size_t payload_len = 0;
1135         int rc;
1136
1137         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1138         if (rc) {
1139                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1140                        auth_tok->token_type);
1141                 goto out;
1142         }
1143         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1144                                  &payload, &payload_len);
1145         if (rc) {
1146                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1147                 goto out;
1148         }
1149         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1150         if (rc) {
1151                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1152                                 "ecryptfsd: %d\n", rc);
1153                 goto out;
1154         }
1155         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1156         if (rc) {
1157                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1158                                 "from the user space daemon\n");
1159                 rc = -EIO;
1160                 goto out;
1161         }
1162         rc = parse_tag_65_packet(&(auth_tok->session_key),
1163                                  &cipher_code, msg);
1164         if (rc) {
1165                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1166                        rc);
1167                 goto out;
1168         }
1169         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1170         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1171                auth_tok->session_key.decrypted_key_size);
1172         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1173         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1174         if (rc) {
1175                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1176                                 cipher_code);
1177                 goto out;
1178         }
1179         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1180         if (ecryptfs_verbosity > 0) {
1181                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1182                 ecryptfs_dump_hex(crypt_stat->key,
1183                                   crypt_stat->key_size);
1184         }
1185 out:
1186         kfree(msg);
1187         kfree(payload);
1188         return rc;
1189 }
1190
1191 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1192 {
1193         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1194         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1195
1196         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1197                                  auth_tok_list_head, list) {
1198                 list_del(&auth_tok_list_item->list);
1199                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1200                                 auth_tok_list_item);
1201         }
1202 }
1203
1204 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1205
1206 /**
1207  * parse_tag_1_packet
1208  * @crypt_stat: The cryptographic context to modify based on packet contents
1209  * @data: The raw bytes of the packet.
1210  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1211  *                 a new authentication token will be placed at the
1212  *                 end of this list for this packet.
1213  * @new_auth_tok: Pointer to a pointer to memory that this function
1214  *                allocates; sets the memory address of the pointer to
1215  *                NULL on error. This object is added to the
1216  *                auth_tok_list.
1217  * @packet_size: This function writes the size of the parsed packet
1218  *               into this memory location; zero on error.
1219  * @max_packet_size: The maximum allowable packet size
1220  *
1221  * Returns zero on success; non-zero on error.
1222  */
1223 static int
1224 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1225                    unsigned char *data, struct list_head *auth_tok_list,
1226                    struct ecryptfs_auth_tok **new_auth_tok,
1227                    size_t *packet_size, size_t max_packet_size)
1228 {
1229         size_t body_size;
1230         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1231         size_t length_size;
1232         int rc = 0;
1233
1234         (*packet_size) = 0;
1235         (*new_auth_tok) = NULL;
1236         /**
1237          * This format is inspired by OpenPGP; see RFC 2440
1238          * packet tag 1
1239          *
1240          * Tag 1 identifier (1 byte)
1241          * Max Tag 1 packet size (max 3 bytes)
1242          * Version (1 byte)
1243          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1244          * Cipher identifier (1 byte)
1245          * Encrypted key size (arbitrary)
1246          *
1247          * 12 bytes minimum packet size
1248          */
1249         if (unlikely(max_packet_size < 12)) {
1250                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1251                 rc = -EINVAL;
1252                 goto out;
1253         }
1254         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1255                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1256                        ECRYPTFS_TAG_1_PACKET_TYPE);
1257                 rc = -EINVAL;
1258                 goto out;
1259         }
1260         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1261          * at end of function upon failure */
1262         auth_tok_list_item =
1263                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1264                                   GFP_KERNEL);
1265         if (!auth_tok_list_item) {
1266                 printk(KERN_ERR "Unable to allocate memory\n");
1267                 rc = -ENOMEM;
1268                 goto out;
1269         }
1270         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1271         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1272                                           &length_size);
1273         if (rc) {
1274                 printk(KERN_WARNING "Error parsing packet length; "
1275                        "rc = [%d]\n", rc);
1276                 goto out_free;
1277         }
1278         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1279                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1280                 rc = -EINVAL;
1281                 goto out_free;
1282         }
1283         (*packet_size) += length_size;
1284         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1285                 printk(KERN_WARNING "Packet size exceeds max\n");
1286                 rc = -EINVAL;
1287                 goto out_free;
1288         }
1289         if (unlikely(data[(*packet_size)++] != 0x03)) {
1290                 printk(KERN_WARNING "Unknown version number [%d]\n",
1291                        data[(*packet_size) - 1]);
1292                 rc = -EINVAL;
1293                 goto out_free;
1294         }
1295         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1296                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1297         *packet_size += ECRYPTFS_SIG_SIZE;
1298         /* This byte is skipped because the kernel does not need to
1299          * know which public key encryption algorithm was used */
1300         (*packet_size)++;
1301         (*new_auth_tok)->session_key.encrypted_key_size =
1302                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1303         if ((*new_auth_tok)->session_key.encrypted_key_size
1304             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1305                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1306                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1307                 rc = -EINVAL;
1308                 goto out_free;
1309         }
1310         memcpy((*new_auth_tok)->session_key.encrypted_key,
1311                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1312         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1313         (*new_auth_tok)->session_key.flags &=
1314                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1315         (*new_auth_tok)->session_key.flags |=
1316                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1317         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1318         (*new_auth_tok)->flags = 0;
1319         (*new_auth_tok)->session_key.flags &=
1320                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1321         (*new_auth_tok)->session_key.flags &=
1322                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1323         list_add(&auth_tok_list_item->list, auth_tok_list);
1324         goto out;
1325 out_free:
1326         (*new_auth_tok) = NULL;
1327         memset(auth_tok_list_item, 0,
1328                sizeof(struct ecryptfs_auth_tok_list_item));
1329         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1330                         auth_tok_list_item);
1331 out:
1332         if (rc)
1333                 (*packet_size) = 0;
1334         return rc;
1335 }
1336
1337 /**
1338  * parse_tag_3_packet
1339  * @crypt_stat: The cryptographic context to modify based on packet
1340  *              contents.
1341  * @data: The raw bytes of the packet.
1342  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1343  *                 a new authentication token will be placed at the end
1344  *                 of this list for this packet.
1345  * @new_auth_tok: Pointer to a pointer to memory that this function
1346  *                allocates; sets the memory address of the pointer to
1347  *                NULL on error. This object is added to the
1348  *                auth_tok_list.
1349  * @packet_size: This function writes the size of the parsed packet
1350  *               into this memory location; zero on error.
1351  * @max_packet_size: maximum number of bytes to parse
1352  *
1353  * Returns zero on success; non-zero on error.
1354  */
1355 static int
1356 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1357                    unsigned char *data, struct list_head *auth_tok_list,
1358                    struct ecryptfs_auth_tok **new_auth_tok,
1359                    size_t *packet_size, size_t max_packet_size)
1360 {
1361         size_t body_size;
1362         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1363         size_t length_size;
1364         int rc = 0;
1365
1366         (*packet_size) = 0;
1367         (*new_auth_tok) = NULL;
1368         /**
1369          *This format is inspired by OpenPGP; see RFC 2440
1370          * packet tag 3
1371          *
1372          * Tag 3 identifier (1 byte)
1373          * Max Tag 3 packet size (max 3 bytes)
1374          * Version (1 byte)
1375          * Cipher code (1 byte)
1376          * S2K specifier (1 byte)
1377          * Hash identifier (1 byte)
1378          * Salt (ECRYPTFS_SALT_SIZE)
1379          * Hash iterations (1 byte)
1380          * Encrypted key (arbitrary)
1381          *
1382          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1383          */
1384         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1385                 printk(KERN_ERR "Max packet size too large\n");
1386                 rc = -EINVAL;
1387                 goto out;
1388         }
1389         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1390                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1391                        ECRYPTFS_TAG_3_PACKET_TYPE);
1392                 rc = -EINVAL;
1393                 goto out;
1394         }
1395         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1396          * at end of function upon failure */
1397         auth_tok_list_item =
1398             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1399         if (!auth_tok_list_item) {
1400                 printk(KERN_ERR "Unable to allocate memory\n");
1401                 rc = -ENOMEM;
1402                 goto out;
1403         }
1404         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1405         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1406                                           &length_size);
1407         if (rc) {
1408                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1409                        rc);
1410                 goto out_free;
1411         }
1412         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1413                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1414                 rc = -EINVAL;
1415                 goto out_free;
1416         }
1417         (*packet_size) += length_size;
1418         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1419                 printk(KERN_ERR "Packet size exceeds max\n");
1420                 rc = -EINVAL;
1421                 goto out_free;
1422         }
1423         (*new_auth_tok)->session_key.encrypted_key_size =
1424                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1425         if ((*new_auth_tok)->session_key.encrypted_key_size
1426             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1427                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1428                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1429                 rc = -EINVAL;
1430                 goto out_free;
1431         }
1432         if (unlikely(data[(*packet_size)++] != 0x04)) {
1433                 printk(KERN_WARNING "Unknown version number [%d]\n",
1434                        data[(*packet_size) - 1]);
1435                 rc = -EINVAL;
1436                 goto out_free;
1437         }
1438         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1439                                             (u16)data[(*packet_size)]);
1440         if (rc)
1441                 goto out_free;
1442         /* A little extra work to differentiate among the AES key
1443          * sizes; see RFC2440 */
1444         switch(data[(*packet_size)++]) {
1445         case RFC2440_CIPHER_AES_192:
1446                 crypt_stat->key_size = 24;
1447                 break;
1448         default:
1449                 crypt_stat->key_size =
1450                         (*new_auth_tok)->session_key.encrypted_key_size;
1451         }
1452         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1453         if (rc)
1454                 goto out_free;
1455         if (unlikely(data[(*packet_size)++] != 0x03)) {
1456                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1457                 rc = -ENOSYS;
1458                 goto out_free;
1459         }
1460         /* TODO: finish the hash mapping */
1461         switch (data[(*packet_size)++]) {
1462         case 0x01: /* See RFC2440 for these numbers and their mappings */
1463                 /* Choose MD5 */
1464                 memcpy((*new_auth_tok)->token.password.salt,
1465                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1466                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1467                 /* This conversion was taken straight from RFC2440 */
1468                 (*new_auth_tok)->token.password.hash_iterations =
1469                         ((u32) 16 + (data[(*packet_size)] & 15))
1470                                 << ((data[(*packet_size)] >> 4) + 6);
1471                 (*packet_size)++;
1472                 /* Friendly reminder:
1473                  * (*new_auth_tok)->session_key.encrypted_key_size =
1474                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1475                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1476                        &data[(*packet_size)],
1477                        (*new_auth_tok)->session_key.encrypted_key_size);
1478                 (*packet_size) +=
1479                         (*new_auth_tok)->session_key.encrypted_key_size;
1480                 (*new_auth_tok)->session_key.flags &=
1481                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1482                 (*new_auth_tok)->session_key.flags |=
1483                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1484                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1485                 break;
1486         default:
1487                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1488                                 "[%d]\n", data[(*packet_size) - 1]);
1489                 rc = -ENOSYS;
1490                 goto out_free;
1491         }
1492         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1493         /* TODO: Parametarize; we might actually want userspace to
1494          * decrypt the session key. */
1495         (*new_auth_tok)->session_key.flags &=
1496                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1497         (*new_auth_tok)->session_key.flags &=
1498                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1499         list_add(&auth_tok_list_item->list, auth_tok_list);
1500         goto out;
1501 out_free:
1502         (*new_auth_tok) = NULL;
1503         memset(auth_tok_list_item, 0,
1504                sizeof(struct ecryptfs_auth_tok_list_item));
1505         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1506                         auth_tok_list_item);
1507 out:
1508         if (rc)
1509                 (*packet_size) = 0;
1510         return rc;
1511 }
1512
1513 /**
1514  * parse_tag_11_packet
1515  * @data: The raw bytes of the packet
1516  * @contents: This function writes the data contents of the literal
1517  *            packet into this memory location
1518  * @max_contents_bytes: The maximum number of bytes that this function
1519  *                      is allowed to write into contents
1520  * @tag_11_contents_size: This function writes the size of the parsed
1521  *                        contents into this memory location; zero on
1522  *                        error
1523  * @packet_size: This function writes the size of the parsed packet
1524  *               into this memory location; zero on error
1525  * @max_packet_size: maximum number of bytes to parse
1526  *
1527  * Returns zero on success; non-zero on error.
1528  */
1529 static int
1530 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1531                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1532                     size_t *packet_size, size_t max_packet_size)
1533 {
1534         size_t body_size;
1535         size_t length_size;
1536         int rc = 0;
1537
1538         (*packet_size) = 0;
1539         (*tag_11_contents_size) = 0;
1540         /* This format is inspired by OpenPGP; see RFC 2440
1541          * packet tag 11
1542          *
1543          * Tag 11 identifier (1 byte)
1544          * Max Tag 11 packet size (max 3 bytes)
1545          * Binary format specifier (1 byte)
1546          * Filename length (1 byte)
1547          * Filename ("_CONSOLE") (8 bytes)
1548          * Modification date (4 bytes)
1549          * Literal data (arbitrary)
1550          *
1551          * We need at least 16 bytes of data for the packet to even be
1552          * valid.
1553          */
1554         if (max_packet_size < 16) {
1555                 printk(KERN_ERR "Maximum packet size too small\n");
1556                 rc = -EINVAL;
1557                 goto out;
1558         }
1559         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1560                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1561                 rc = -EINVAL;
1562                 goto out;
1563         }
1564         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1565                                           &length_size);
1566         if (rc) {
1567                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1568                 goto out;
1569         }
1570         if (body_size < 14) {
1571                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1572                 rc = -EINVAL;
1573                 goto out;
1574         }
1575         (*packet_size) += length_size;
1576         (*tag_11_contents_size) = (body_size - 14);
1577         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1578                 printk(KERN_ERR "Packet size exceeds max\n");
1579                 rc = -EINVAL;
1580                 goto out;
1581         }
1582         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1583                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1584                        "expected size\n");
1585                 rc = -EINVAL;
1586                 goto out;
1587         }
1588         if (data[(*packet_size)++] != 0x62) {
1589                 printk(KERN_WARNING "Unrecognizable packet\n");
1590                 rc = -EINVAL;
1591                 goto out;
1592         }
1593         if (data[(*packet_size)++] != 0x08) {
1594                 printk(KERN_WARNING "Unrecognizable packet\n");
1595                 rc = -EINVAL;
1596                 goto out;
1597         }
1598         (*packet_size) += 12; /* Ignore filename and modification date */
1599         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1600         (*packet_size) += (*tag_11_contents_size);
1601 out:
1602         if (rc) {
1603                 (*packet_size) = 0;
1604                 (*tag_11_contents_size) = 0;
1605         }
1606         return rc;
1607 }
1608
1609 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1610                                       struct ecryptfs_auth_tok **auth_tok,
1611                                       char *sig)
1612 {
1613         int rc = 0;
1614
1615         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1616         if (IS_ERR(*auth_tok_key)) {
1617                 (*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1618                 if (IS_ERR(*auth_tok_key)) {
1619                         printk(KERN_ERR "Could not find key with description: [%s]\n",
1620                               sig);
1621                         rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1622                         (*auth_tok_key) = NULL;
1623                         goto out;
1624                 }
1625         }
1626         down_write(&(*auth_tok_key)->sem);
1627         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1628         if (rc) {
1629                 up_write(&(*auth_tok_key)->sem);
1630                 key_put(*auth_tok_key);
1631                 (*auth_tok_key) = NULL;
1632                 goto out;
1633         }
1634 out:
1635         return rc;
1636 }
1637
1638 /**
1639  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1640  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1641  * @crypt_stat: The cryptographic context
1642  *
1643  * Returns zero on success; non-zero error otherwise
1644  */
1645 static int
1646 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1647                                          struct ecryptfs_crypt_stat *crypt_stat)
1648 {
1649         struct scatterlist dst_sg[2];
1650         struct scatterlist src_sg[2];
1651         struct mutex *tfm_mutex;
1652         struct crypto_skcipher *tfm;
1653         struct skcipher_request *req = NULL;
1654         int rc = 0;
1655
1656         if (unlikely(ecryptfs_verbosity > 0)) {
1657                 ecryptfs_printk(
1658                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1659                         auth_tok->token.password.session_key_encryption_key_bytes);
1660                 ecryptfs_dump_hex(
1661                         auth_tok->token.password.session_key_encryption_key,
1662                         auth_tok->token.password.session_key_encryption_key_bytes);
1663         }
1664         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
1665                                                         crypt_stat->cipher);
1666         if (unlikely(rc)) {
1667                 printk(KERN_ERR "Internal error whilst attempting to get "
1668                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1669                        crypt_stat->cipher, rc);
1670                 goto out;
1671         }
1672         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1673                                  auth_tok->session_key.encrypted_key_size,
1674                                  src_sg, 2);
1675         if (rc < 1 || rc > 2) {
1676                 printk(KERN_ERR "Internal error whilst attempting to convert "
1677                         "auth_tok->session_key.encrypted_key to scatterlist; "
1678                         "expected rc = 1; got rc = [%d]. "
1679                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1680                         auth_tok->session_key.encrypted_key_size);
1681                 goto out;
1682         }
1683         auth_tok->session_key.decrypted_key_size =
1684                 auth_tok->session_key.encrypted_key_size;
1685         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1686                                  auth_tok->session_key.decrypted_key_size,
1687                                  dst_sg, 2);
1688         if (rc < 1 || rc > 2) {
1689                 printk(KERN_ERR "Internal error whilst attempting to convert "
1690                         "auth_tok->session_key.decrypted_key to scatterlist; "
1691                         "expected rc = 1; got rc = [%d]\n", rc);
1692                 goto out;
1693         }
1694         mutex_lock(tfm_mutex);
1695         req = skcipher_request_alloc(tfm, GFP_KERNEL);
1696         if (!req) {
1697                 mutex_unlock(tfm_mutex);
1698                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1699                        "skcipher_request_alloc for %s\n", __func__,
1700                        crypto_skcipher_driver_name(tfm));
1701                 rc = -ENOMEM;
1702                 goto out;
1703         }
1704
1705         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
1706                                       NULL, NULL);
1707         rc = crypto_skcipher_setkey(
1708                 tfm, auth_tok->token.password.session_key_encryption_key,
1709                 crypt_stat->key_size);
1710         if (unlikely(rc < 0)) {
1711                 mutex_unlock(tfm_mutex);
1712                 printk(KERN_ERR "Error setting key for crypto context\n");
1713                 rc = -EINVAL;
1714                 goto out;
1715         }
1716         skcipher_request_set_crypt(req, src_sg, dst_sg,
1717                                    auth_tok->session_key.encrypted_key_size,
1718                                    NULL);
1719         rc = crypto_skcipher_decrypt(req);
1720         mutex_unlock(tfm_mutex);
1721         if (unlikely(rc)) {
1722                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1723                 goto out;
1724         }
1725         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1726         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1727                auth_tok->session_key.decrypted_key_size);
1728         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1729         if (unlikely(ecryptfs_verbosity > 0)) {
1730                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1731                                 crypt_stat->key_size);
1732                 ecryptfs_dump_hex(crypt_stat->key,
1733                                   crypt_stat->key_size);
1734         }
1735 out:
1736         skcipher_request_free(req);
1737         return rc;
1738 }
1739
1740 /**
1741  * ecryptfs_parse_packet_set
1742  * @crypt_stat: The cryptographic context
1743  * @src: Virtual address of region of memory containing the packets
1744  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1745  *
1746  * Get crypt_stat to have the file's session key if the requisite key
1747  * is available to decrypt the session key.
1748  *
1749  * Returns Zero if a valid authentication token was retrieved and
1750  * processed; negative value for file not encrypted or for error
1751  * conditions.
1752  */
1753 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1754                               unsigned char *src,
1755                               struct dentry *ecryptfs_dentry)
1756 {
1757         size_t i = 0;
1758         size_t found_auth_tok;
1759         size_t next_packet_is_auth_tok_packet;
1760         struct list_head auth_tok_list;
1761         struct ecryptfs_auth_tok *matching_auth_tok;
1762         struct ecryptfs_auth_tok *candidate_auth_tok;
1763         char *candidate_auth_tok_sig;
1764         size_t packet_size;
1765         struct ecryptfs_auth_tok *new_auth_tok;
1766         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1767         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1768         size_t tag_11_contents_size;
1769         size_t tag_11_packet_size;
1770         struct key *auth_tok_key = NULL;
1771         int rc = 0;
1772
1773         INIT_LIST_HEAD(&auth_tok_list);
1774         /* Parse the header to find as many packets as we can; these will be
1775          * added the our &auth_tok_list */
1776         next_packet_is_auth_tok_packet = 1;
1777         while (next_packet_is_auth_tok_packet) {
1778                 size_t max_packet_size = ((PAGE_SIZE - 8) - i);
1779
1780                 switch (src[i]) {
1781                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1782                         rc = parse_tag_3_packet(crypt_stat,
1783                                                 (unsigned char *)&src[i],
1784                                                 &auth_tok_list, &new_auth_tok,
1785                                                 &packet_size, max_packet_size);
1786                         if (rc) {
1787                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1788                                                 "tag 3 packet\n");
1789                                 rc = -EIO;
1790                                 goto out_wipe_list;
1791                         }
1792                         i += packet_size;
1793                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1794                                                  sig_tmp_space,
1795                                                  ECRYPTFS_SIG_SIZE,
1796                                                  &tag_11_contents_size,
1797                                                  &tag_11_packet_size,
1798                                                  max_packet_size);
1799                         if (rc) {
1800                                 ecryptfs_printk(KERN_ERR, "No valid "
1801                                                 "(ecryptfs-specific) literal "
1802                                                 "packet containing "
1803                                                 "authentication token "
1804                                                 "signature found after "
1805                                                 "tag 3 packet\n");
1806                                 rc = -EIO;
1807                                 goto out_wipe_list;
1808                         }
1809                         i += tag_11_packet_size;
1810                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1811                                 ecryptfs_printk(KERN_ERR, "Expected "
1812                                                 "signature of size [%d]; "
1813                                                 "read size [%zd]\n",
1814                                                 ECRYPTFS_SIG_SIZE,
1815                                                 tag_11_contents_size);
1816                                 rc = -EIO;
1817                                 goto out_wipe_list;
1818                         }
1819                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1820                                         sig_tmp_space, tag_11_contents_size);
1821                         new_auth_tok->token.password.signature[
1822                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1823                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1824                         break;
1825                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1826                         rc = parse_tag_1_packet(crypt_stat,
1827                                                 (unsigned char *)&src[i],
1828                                                 &auth_tok_list, &new_auth_tok,
1829                                                 &packet_size, max_packet_size);
1830                         if (rc) {
1831                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1832                                                 "tag 1 packet\n");
1833                                 rc = -EIO;
1834                                 goto out_wipe_list;
1835                         }
1836                         i += packet_size;
1837                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1838                         break;
1839                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1840                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1841                                         "(Tag 11 not allowed by itself)\n");
1842                         rc = -EIO;
1843                         goto out_wipe_list;
1844                 default:
1845                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1846                                         "of the file header; hex value of "
1847                                         "character is [0x%.2x]\n", i, src[i]);
1848                         next_packet_is_auth_tok_packet = 0;
1849                 }
1850         }
1851         if (list_empty(&auth_tok_list)) {
1852                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1853                        "eCryptfs file; this is not supported in this version "
1854                        "of the eCryptfs kernel module\n");
1855                 rc = -EINVAL;
1856                 goto out;
1857         }
1858         /* auth_tok_list contains the set of authentication tokens
1859          * parsed from the metadata. We need to find a matching
1860          * authentication token that has the secret component(s)
1861          * necessary to decrypt the EFEK in the auth_tok parsed from
1862          * the metadata. There may be several potential matches, but
1863          * just one will be sufficient to decrypt to get the FEK. */
1864 find_next_matching_auth_tok:
1865         found_auth_tok = 0;
1866         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1867                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1868                 if (unlikely(ecryptfs_verbosity > 0)) {
1869                         ecryptfs_printk(KERN_DEBUG,
1870                                         "Considering candidate auth tok:\n");
1871                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1872                 }
1873                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1874                                                candidate_auth_tok);
1875                 if (rc) {
1876                         printk(KERN_ERR
1877                                "Unrecognized candidate auth tok type: [%d]\n",
1878                                candidate_auth_tok->token_type);
1879                         rc = -EINVAL;
1880                         goto out_wipe_list;
1881                 }
1882                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1883                                                &matching_auth_tok,
1884                                                crypt_stat->mount_crypt_stat,
1885                                                candidate_auth_tok_sig);
1886                 if (!rc) {
1887                         found_auth_tok = 1;
1888                         goto found_matching_auth_tok;
1889                 }
1890         }
1891         if (!found_auth_tok) {
1892                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1893                                 "authentication token\n");
1894                 rc = -EIO;
1895                 goto out_wipe_list;
1896         }
1897 found_matching_auth_tok:
1898         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1899                 memcpy(&(candidate_auth_tok->token.private_key),
1900                        &(matching_auth_tok->token.private_key),
1901                        sizeof(struct ecryptfs_private_key));
1902                 up_write(&(auth_tok_key->sem));
1903                 key_put(auth_tok_key);
1904                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1905                                                        crypt_stat);
1906         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1907                 memcpy(&(candidate_auth_tok->token.password),
1908                        &(matching_auth_tok->token.password),
1909                        sizeof(struct ecryptfs_password));
1910                 up_write(&(auth_tok_key->sem));
1911                 key_put(auth_tok_key);
1912                 rc = decrypt_passphrase_encrypted_session_key(
1913                         candidate_auth_tok, crypt_stat);
1914         } else {
1915                 up_write(&(auth_tok_key->sem));
1916                 key_put(auth_tok_key);
1917                 rc = -EINVAL;
1918         }
1919         if (rc) {
1920                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1921
1922                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1923                                 "session key for authentication token with sig "
1924                                 "[%.*s]; rc = [%d]. Removing auth tok "
1925                                 "candidate from the list and searching for "
1926                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1927                                 candidate_auth_tok_sig, rc);
1928                 list_for_each_entry_safe(auth_tok_list_item,
1929                                          auth_tok_list_item_tmp,
1930                                          &auth_tok_list, list) {
1931                         if (candidate_auth_tok
1932                             == &auth_tok_list_item->auth_tok) {
1933                                 list_del(&auth_tok_list_item->list);
1934                                 kmem_cache_free(
1935                                         ecryptfs_auth_tok_list_item_cache,
1936                                         auth_tok_list_item);
1937                                 goto find_next_matching_auth_tok;
1938                         }
1939                 }
1940                 BUG();
1941         }
1942         rc = ecryptfs_compute_root_iv(crypt_stat);
1943         if (rc) {
1944                 ecryptfs_printk(KERN_ERR, "Error computing "
1945                                 "the root IV\n");
1946                 goto out_wipe_list;
1947         }
1948         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1949         if (rc) {
1950                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1951                                 "context for cipher [%s]; rc = [%d]\n",
1952                                 crypt_stat->cipher, rc);
1953         }
1954 out_wipe_list:
1955         wipe_auth_tok_list(&auth_tok_list);
1956 out:
1957         return rc;
1958 }
1959
1960 static int
1961 pki_encrypt_session_key(struct key *auth_tok_key,
1962                         struct ecryptfs_auth_tok *auth_tok,
1963                         struct ecryptfs_crypt_stat *crypt_stat,
1964                         struct ecryptfs_key_record *key_rec)
1965 {
1966         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1967         char *payload = NULL;
1968         size_t payload_len = 0;
1969         struct ecryptfs_message *msg;
1970         int rc;
1971
1972         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1973                                  ecryptfs_code_for_cipher_string(
1974                                          crypt_stat->cipher,
1975                                          crypt_stat->key_size),
1976                                  crypt_stat, &payload, &payload_len);
1977         up_write(&(auth_tok_key->sem));
1978         key_put(auth_tok_key);
1979         if (rc) {
1980                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1981                 goto out;
1982         }
1983         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1984         if (rc) {
1985                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1986                                 "ecryptfsd: %d\n", rc);
1987                 goto out;
1988         }
1989         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1990         if (rc) {
1991                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1992                                 "from the user space daemon\n");
1993                 rc = -EIO;
1994                 goto out;
1995         }
1996         rc = parse_tag_67_packet(key_rec, msg);
1997         if (rc)
1998                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
1999         kfree(msg);
2000 out:
2001         kfree(payload);
2002         return rc;
2003 }
2004 /**
2005  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2006  * @dest: Buffer into which to write the packet
2007  * @remaining_bytes: Maximum number of bytes that can be writtn
2008  * @auth_tok_key: The authentication token key to unlock and put when done with
2009  *                @auth_tok
2010  * @auth_tok: The authentication token used for generating the tag 1 packet
2011  * @crypt_stat: The cryptographic context
2012  * @key_rec: The key record struct for the tag 1 packet
2013  * @packet_size: This function will write the number of bytes that end
2014  *               up constituting the packet; set to zero on error
2015  *
2016  * Returns zero on success; non-zero on error.
2017  */
2018 static int
2019 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2020                    struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2021                    struct ecryptfs_crypt_stat *crypt_stat,
2022                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2023 {
2024         size_t i;
2025         size_t encrypted_session_key_valid = 0;
2026         size_t packet_size_length;
2027         size_t max_packet_size;
2028         int rc = 0;
2029
2030         (*packet_size) = 0;
2031         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2032                           ECRYPTFS_SIG_SIZE);
2033         encrypted_session_key_valid = 0;
2034         for (i = 0; i < crypt_stat->key_size; i++)
2035                 encrypted_session_key_valid |=
2036                         auth_tok->session_key.encrypted_key[i];
2037         if (encrypted_session_key_valid) {
2038                 memcpy(key_rec->enc_key,
2039                        auth_tok->session_key.encrypted_key,
2040                        auth_tok->session_key.encrypted_key_size);
2041                 up_write(&(auth_tok_key->sem));
2042                 key_put(auth_tok_key);
2043                 goto encrypted_session_key_set;
2044         }
2045         if (auth_tok->session_key.encrypted_key_size == 0)
2046                 auth_tok->session_key.encrypted_key_size =
2047                         auth_tok->token.private_key.key_size;
2048         rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2049                                      key_rec);
2050         if (rc) {
2051                 printk(KERN_ERR "Failed to encrypt session key via a key "
2052                        "module; rc = [%d]\n", rc);
2053                 goto out;
2054         }
2055         if (ecryptfs_verbosity > 0) {
2056                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2057                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2058         }
2059 encrypted_session_key_set:
2060         /* This format is inspired by OpenPGP; see RFC 2440
2061          * packet tag 1 */
2062         max_packet_size = (1                         /* Tag 1 identifier */
2063                            + 3                       /* Max Tag 1 packet size */
2064                            + 1                       /* Version */
2065                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2066                            + 1                       /* Cipher identifier */
2067                            + key_rec->enc_key_size); /* Encrypted key size */
2068         if (max_packet_size > (*remaining_bytes)) {
2069                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2070                        "need up to [%td] bytes, but there are only [%td] "
2071                        "available\n", max_packet_size, (*remaining_bytes));
2072                 rc = -EINVAL;
2073                 goto out;
2074         }
2075         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2076         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2077                                           (max_packet_size - 4),
2078                                           &packet_size_length);
2079         if (rc) {
2080                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2081                                 "header; cannot generate packet length\n");
2082                 goto out;
2083         }
2084         (*packet_size) += packet_size_length;
2085         dest[(*packet_size)++] = 0x03; /* version 3 */
2086         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2087         (*packet_size) += ECRYPTFS_SIG_SIZE;
2088         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2089         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2090                key_rec->enc_key_size);
2091         (*packet_size) += key_rec->enc_key_size;
2092 out:
2093         if (rc)
2094                 (*packet_size) = 0;
2095         else
2096                 (*remaining_bytes) -= (*packet_size);
2097         return rc;
2098 }
2099
2100 /**
2101  * write_tag_11_packet
2102  * @dest: Target into which Tag 11 packet is to be written
2103  * @remaining_bytes: Maximum packet length
2104  * @contents: Byte array of contents to copy in
2105  * @contents_length: Number of bytes in contents
2106  * @packet_length: Length of the Tag 11 packet written; zero on error
2107  *
2108  * Returns zero on success; non-zero on error.
2109  */
2110 static int
2111 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2112                     size_t contents_length, size_t *packet_length)
2113 {
2114         size_t packet_size_length;
2115         size_t max_packet_size;
2116         int rc = 0;
2117
2118         (*packet_length) = 0;
2119         /* This format is inspired by OpenPGP; see RFC 2440
2120          * packet tag 11 */
2121         max_packet_size = (1                   /* Tag 11 identifier */
2122                            + 3                 /* Max Tag 11 packet size */
2123                            + 1                 /* Binary format specifier */
2124                            + 1                 /* Filename length */
2125                            + 8                 /* Filename ("_CONSOLE") */
2126                            + 4                 /* Modification date */
2127                            + contents_length); /* Literal data */
2128         if (max_packet_size > (*remaining_bytes)) {
2129                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2130                        "need up to [%td] bytes, but there are only [%td] "
2131                        "available\n", max_packet_size, (*remaining_bytes));
2132                 rc = -EINVAL;
2133                 goto out;
2134         }
2135         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2136         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2137                                           (max_packet_size - 4),
2138                                           &packet_size_length);
2139         if (rc) {
2140                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2141                        "generate packet length. rc = [%d]\n", rc);
2142                 goto out;
2143         }
2144         (*packet_length) += packet_size_length;
2145         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2146         dest[(*packet_length)++] = 8;
2147         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2148         (*packet_length) += 8;
2149         memset(&dest[(*packet_length)], 0x00, 4);
2150         (*packet_length) += 4;
2151         memcpy(&dest[(*packet_length)], contents, contents_length);
2152         (*packet_length) += contents_length;
2153  out:
2154         if (rc)
2155                 (*packet_length) = 0;
2156         else
2157                 (*remaining_bytes) -= (*packet_length);
2158         return rc;
2159 }
2160
2161 /**
2162  * write_tag_3_packet
2163  * @dest: Buffer into which to write the packet
2164  * @remaining_bytes: Maximum number of bytes that can be written
2165  * @auth_tok: Authentication token
2166  * @crypt_stat: The cryptographic context
2167  * @key_rec: encrypted key
2168  * @packet_size: This function will write the number of bytes that end
2169  *               up constituting the packet; set to zero on error
2170  *
2171  * Returns zero on success; non-zero on error.
2172  */
2173 static int
2174 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2175                    struct ecryptfs_auth_tok *auth_tok,
2176                    struct ecryptfs_crypt_stat *crypt_stat,
2177                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2178 {
2179         size_t i;
2180         size_t encrypted_session_key_valid = 0;
2181         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2182         struct scatterlist dst_sg[2];
2183         struct scatterlist src_sg[2];
2184         struct mutex *tfm_mutex = NULL;
2185         u8 cipher_code;
2186         size_t packet_size_length;
2187         size_t max_packet_size;
2188         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2189                 crypt_stat->mount_crypt_stat;
2190         struct crypto_skcipher *tfm;
2191         struct skcipher_request *req;
2192         int rc = 0;
2193
2194         (*packet_size) = 0;
2195         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2196                           ECRYPTFS_SIG_SIZE);
2197         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2198                                                         crypt_stat->cipher);
2199         if (unlikely(rc)) {
2200                 printk(KERN_ERR "Internal error whilst attempting to get "
2201                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2202                        crypt_stat->cipher, rc);
2203                 goto out;
2204         }
2205         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2206                 printk(KERN_WARNING "No key size specified at mount; "
2207                        "defaulting to [%d]\n",
2208                        crypto_skcipher_max_keysize(tfm));
2209                 mount_crypt_stat->global_default_cipher_key_size =
2210                         crypto_skcipher_max_keysize(tfm);
2211         }
2212         if (crypt_stat->key_size == 0)
2213                 crypt_stat->key_size =
2214                         mount_crypt_stat->global_default_cipher_key_size;
2215         if (auth_tok->session_key.encrypted_key_size == 0)
2216                 auth_tok->session_key.encrypted_key_size =
2217                         crypt_stat->key_size;
2218         if (crypt_stat->key_size == 24
2219             && strcmp("aes", crypt_stat->cipher) == 0) {
2220                 memset((crypt_stat->key + 24), 0, 8);
2221                 auth_tok->session_key.encrypted_key_size = 32;
2222         } else
2223                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2224         key_rec->enc_key_size =
2225                 auth_tok->session_key.encrypted_key_size;
2226         encrypted_session_key_valid = 0;
2227         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2228                 encrypted_session_key_valid |=
2229                         auth_tok->session_key.encrypted_key[i];
2230         if (encrypted_session_key_valid) {
2231                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2232                                 "using auth_tok->session_key.encrypted_key, "
2233                                 "where key_rec->enc_key_size = [%zd]\n",
2234                                 key_rec->enc_key_size);
2235                 memcpy(key_rec->enc_key,
2236                        auth_tok->session_key.encrypted_key,
2237                        key_rec->enc_key_size);
2238                 goto encrypted_session_key_set;
2239         }
2240         if (auth_tok->token.password.flags &
2241             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2242                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2243                                 "session key encryption key of size [%d]\n",
2244                                 auth_tok->token.password.
2245                                 session_key_encryption_key_bytes);
2246                 memcpy(session_key_encryption_key,
2247                        auth_tok->token.password.session_key_encryption_key,
2248                        crypt_stat->key_size);
2249                 ecryptfs_printk(KERN_DEBUG,
2250                                 "Cached session key encryption key:\n");
2251                 if (ecryptfs_verbosity > 0)
2252                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2253         }
2254         if (unlikely(ecryptfs_verbosity > 0)) {
2255                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2256                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2257         }
2258         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2259                                  src_sg, 2);
2260         if (rc < 1 || rc > 2) {
2261                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2262                                 "for crypt_stat session key; expected rc = 1; "
2263                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2264                                 rc, key_rec->enc_key_size);
2265                 rc = -ENOMEM;
2266                 goto out;
2267         }
2268         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2269                                  dst_sg, 2);
2270         if (rc < 1 || rc > 2) {
2271                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2272                                 "for crypt_stat encrypted session key; "
2273                                 "expected rc = 1; got rc = [%d]. "
2274                                 "key_rec->enc_key_size = [%zd]\n", rc,
2275                                 key_rec->enc_key_size);
2276                 rc = -ENOMEM;
2277                 goto out;
2278         }
2279         mutex_lock(tfm_mutex);
2280         rc = crypto_skcipher_setkey(tfm, session_key_encryption_key,
2281                                     crypt_stat->key_size);
2282         if (rc < 0) {
2283                 mutex_unlock(tfm_mutex);
2284                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2285                                 "context; rc = [%d]\n", rc);
2286                 goto out;
2287         }
2288
2289         req = skcipher_request_alloc(tfm, GFP_KERNEL);
2290         if (!req) {
2291                 mutex_unlock(tfm_mutex);
2292                 ecryptfs_printk(KERN_ERR, "Out of kernel memory whilst "
2293                                 "attempting to skcipher_request_alloc for "
2294                                 "%s\n", crypto_skcipher_driver_name(tfm));
2295                 rc = -ENOMEM;
2296                 goto out;
2297         }
2298
2299         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
2300                                       NULL, NULL);
2301
2302         rc = 0;
2303         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2304                         crypt_stat->key_size);
2305         skcipher_request_set_crypt(req, src_sg, dst_sg,
2306                                    (*key_rec).enc_key_size, NULL);
2307         rc = crypto_skcipher_encrypt(req);
2308         mutex_unlock(tfm_mutex);
2309         skcipher_request_free(req);
2310         if (rc) {
2311                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2312                 goto out;
2313         }
2314         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2315         if (ecryptfs_verbosity > 0) {
2316                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2317                                 key_rec->enc_key_size);
2318                 ecryptfs_dump_hex(key_rec->enc_key,
2319                                   key_rec->enc_key_size);
2320         }
2321 encrypted_session_key_set:
2322         /* This format is inspired by OpenPGP; see RFC 2440
2323          * packet tag 3 */
2324         max_packet_size = (1                         /* Tag 3 identifier */
2325                            + 3                       /* Max Tag 3 packet size */
2326                            + 1                       /* Version */
2327                            + 1                       /* Cipher code */
2328                            + 1                       /* S2K specifier */
2329                            + 1                       /* Hash identifier */
2330                            + ECRYPTFS_SALT_SIZE      /* Salt */
2331                            + 1                       /* Hash iterations */
2332                            + key_rec->enc_key_size); /* Encrypted key size */
2333         if (max_packet_size > (*remaining_bytes)) {
2334                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2335                        "there are only [%td] available\n", max_packet_size,
2336                        (*remaining_bytes));
2337                 rc = -EINVAL;
2338                 goto out;
2339         }
2340         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2341         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2342          * to get the number of octets in the actual Tag 3 packet */
2343         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2344                                           (max_packet_size - 4),
2345                                           &packet_size_length);
2346         if (rc) {
2347                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2348                        "generate packet length. rc = [%d]\n", rc);
2349                 goto out;
2350         }
2351         (*packet_size) += packet_size_length;
2352         dest[(*packet_size)++] = 0x04; /* version 4 */
2353         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2354          * specified with strings */
2355         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2356                                                       crypt_stat->key_size);
2357         if (cipher_code == 0) {
2358                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2359                                 "cipher [%s]\n", crypt_stat->cipher);
2360                 rc = -EINVAL;
2361                 goto out;
2362         }
2363         dest[(*packet_size)++] = cipher_code;
2364         dest[(*packet_size)++] = 0x03;  /* S2K */
2365         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2366         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2367                ECRYPTFS_SALT_SIZE);
2368         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2369         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2370         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2371                key_rec->enc_key_size);
2372         (*packet_size) += key_rec->enc_key_size;
2373 out:
2374         if (rc)
2375                 (*packet_size) = 0;
2376         else
2377                 (*remaining_bytes) -= (*packet_size);
2378         return rc;
2379 }
2380
2381 struct kmem_cache *ecryptfs_key_record_cache;
2382
2383 /**
2384  * ecryptfs_generate_key_packet_set
2385  * @dest_base: Virtual address from which to write the key record set
2386  * @crypt_stat: The cryptographic context from which the
2387  *              authentication tokens will be retrieved
2388  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2389  *                   for the global parameters
2390  * @len: The amount written
2391  * @max: The maximum amount of data allowed to be written
2392  *
2393  * Generates a key packet set and writes it to the virtual address
2394  * passed in.
2395  *
2396  * Returns zero on success; non-zero on error.
2397  */
2398 int
2399 ecryptfs_generate_key_packet_set(char *dest_base,
2400                                  struct ecryptfs_crypt_stat *crypt_stat,
2401                                  struct dentry *ecryptfs_dentry, size_t *len,
2402                                  size_t max)
2403 {
2404         struct ecryptfs_auth_tok *auth_tok;
2405         struct key *auth_tok_key = NULL;
2406         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2407                 &ecryptfs_superblock_to_private(
2408                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2409         size_t written;
2410         struct ecryptfs_key_record *key_rec;
2411         struct ecryptfs_key_sig *key_sig;
2412         int rc = 0;
2413
2414         (*len) = 0;
2415         mutex_lock(&crypt_stat->keysig_list_mutex);
2416         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2417         if (!key_rec) {
2418                 rc = -ENOMEM;
2419                 goto out;
2420         }
2421         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2422                             crypt_stat_list) {
2423                 memset(key_rec, 0, sizeof(*key_rec));
2424                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2425                                                            &auth_tok,
2426                                                            mount_crypt_stat,
2427                                                            key_sig->keysig);
2428                 if (rc) {
2429                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2430                                "sig = [%s]\n", key_sig->keysig);
2431                         rc = process_find_global_auth_tok_for_sig_err(rc);
2432                         goto out_free;
2433                 }
2434                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2435                         rc = write_tag_3_packet((dest_base + (*len)),
2436                                                 &max, auth_tok,
2437                                                 crypt_stat, key_rec,
2438                                                 &written);
2439                         up_write(&(auth_tok_key->sem));
2440                         key_put(auth_tok_key);
2441                         if (rc) {
2442                                 ecryptfs_printk(KERN_WARNING, "Error "
2443                                                 "writing tag 3 packet\n");
2444                                 goto out_free;
2445                         }
2446                         (*len) += written;
2447                         /* Write auth tok signature packet */
2448                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2449                                                  key_rec->sig,
2450                                                  ECRYPTFS_SIG_SIZE, &written);
2451                         if (rc) {
2452                                 ecryptfs_printk(KERN_ERR, "Error writing "
2453                                                 "auth tok signature packet\n");
2454                                 goto out_free;
2455                         }
2456                         (*len) += written;
2457                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2458                         rc = write_tag_1_packet(dest_base + (*len), &max,
2459                                                 auth_tok_key, auth_tok,
2460                                                 crypt_stat, key_rec, &written);
2461                         if (rc) {
2462                                 ecryptfs_printk(KERN_WARNING, "Error "
2463                                                 "writing tag 1 packet\n");
2464                                 goto out_free;
2465                         }
2466                         (*len) += written;
2467                 } else {
2468                         up_write(&(auth_tok_key->sem));
2469                         key_put(auth_tok_key);
2470                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2471                                         "authentication token type\n");
2472                         rc = -EINVAL;
2473                         goto out_free;
2474                 }
2475         }
2476         if (likely(max > 0)) {
2477                 dest_base[(*len)] = 0x00;
2478         } else {
2479                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2480                 rc = -EIO;
2481         }
2482 out_free:
2483         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2484 out:
2485         if (rc)
2486                 (*len) = 0;
2487         mutex_unlock(&crypt_stat->keysig_list_mutex);
2488         return rc;
2489 }
2490
2491 struct kmem_cache *ecryptfs_key_sig_cache;
2492
2493 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2494 {
2495         struct ecryptfs_key_sig *new_key_sig;
2496
2497         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2498         if (!new_key_sig)
2499                 return -ENOMEM;
2500
2501         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2502         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2503         /* Caller must hold keysig_list_mutex */
2504         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2505
2506         return 0;
2507 }
2508
2509 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2510
2511 int
2512 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2513                              char *sig, u32 global_auth_tok_flags)
2514 {
2515         struct ecryptfs_global_auth_tok *new_auth_tok;
2516
2517         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2518                                         GFP_KERNEL);
2519         if (!new_auth_tok)
2520                 return -ENOMEM;
2521
2522         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2523         new_auth_tok->flags = global_auth_tok_flags;
2524         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2525         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2526         list_add(&new_auth_tok->mount_crypt_stat_list,
2527                  &mount_crypt_stat->global_auth_tok_list);
2528         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2529         return 0;
2530 }
2531