fs/ecryptfs/keystore.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  * In-kernel key management code.  Includes functions to parse and
   4  * write authentication token-related packets with the underlying
   5  * file.
   6  *
   7  * Copyright (C) 2004-2006 International Business Machines Corp.
   8  *   Author(s): Michael A. Halcrow <[email protected]>
   9  *              Michael C. Thompson <[email protected]>
  10  *              Trevor S. Highland <[email protected]>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  25  * 02111-1307, USA.
  26  */
  27
  28 #include <linux/string.h>
  29 #include <linux/pagemap.h>
  30 #include <linux/key.h>
  31 #include <linux/random.h>
  32 #include <linux/crypto.h>
  33 #include <linux/scatterlist.h>
  34 #include <linux/slab.h>
  35 #include "ecryptfs_kernel.h"
  36
  37 /**
  38  * request_key returned an error instead of a valid key address;
  39  * determine the type of error, make appropriate log entries, and
  40  * return an error code.
  41  */
  42 static int process_request_key_err(long err_code)
  43 {
  44         int rc = 0;
  45
  46         switch (err_code) {
  47         case -ENOKEY:
  48                 ecryptfs_printk(KERN_WARNING, "No key\n");
  49                 rc = -ENOENT;
  50                 break;
  51         case -EKEYEXPIRED:
  52                 ecryptfs_printk(KERN_WARNING, "Key expired\n");
  53                 rc = -ETIME;
  54                 break;
  55         case -EKEYREVOKED:
  56                 ecryptfs_printk(KERN_WARNING, "Key revoked\n");
  57                 rc = -EINVAL;
  58                 break;
  59         default:
  60                 ecryptfs_printk(KERN_WARNING, "Unknown error code: "
  61                                 "[0x%.16lx]\n", err_code);
  62                 rc = -EINVAL;
  63         }
  64         return rc;
  65 }
  66
  67 static int process_find_global_auth_tok_for_sig_err(int err_code)
  68 {
  69         int rc = err_code;
  70
  71         switch (err_code) {
  72         case -ENOENT:
  73                 ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
  74                 break;
  75         case -EINVAL:
  76                 ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
  77                 break;
  78         default:
  79                 rc = process_request_key_err(err_code);
  80                 break;
  81         }
  82         return rc;
  83 }
  84
  85 /**
  86  * ecryptfs_parse_packet_length
  87  * @data: Pointer to memory containing length at offset
  88  * @size: This function writes the decoded size to this memory
  89  *        address; zero on error
  90  * @length_size: The number of bytes occupied by the encoded length
  91  *
  92  * Returns zero on success; non-zero on error
  93  */
  94 int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
  95                                  size_t *length_size)
  96 {
  97         int rc = 0;
  98
  99         (*length_size) = 0;
 100         (*size) = 0;
 101         if (data[0] < 192) {
 102                 /* One-byte length */
 103                 (*size) = data[0];
 104                 (*length_size) = 1;
 105         } else if (data[0] < 224) {
 106                 /* Two-byte length */
 107                 (*size) = (data[0] - 192) * 256;
 108                 (*size) += data[1] + 192;
 109                 (*length_size) = 2;
 110         } else if (data[0] == 255) {
 111                 /* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
 112                 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
 113                                 "supported\n");
 114                 rc = -EINVAL;
 115                 goto out;
 116         } else {
 117                 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
 118                 rc = -EINVAL;
 119                 goto out;
 120         }
 121 out:
 122         return rc;
 123 }
 124
 125 /**
 126  * ecryptfs_write_packet_length
 127  * @dest: The byte array target into which to write the length. Must
 128  *        have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
 129  * @size: The length to write.
 130  * @packet_size_length: The number of bytes used to encode the packet
 131  *                      length is written to this address.
 132  *
 133  * Returns zero on success; non-zero on error.
 134  */
 135 int ecryptfs_write_packet_length(char *dest, size_t size,
 136                                  size_t *packet_size_length)
 137 {
 138         int rc = 0;
 139
 140         if (size < 192) {
 141                 dest[0] = size;
 142                 (*packet_size_length) = 1;
 143         } else if (size < 65536) {
 144                 dest[0] = (((size - 192) / 256) + 192);
 145                 dest[1] = ((size - 192) % 256);
 146                 (*packet_size_length) = 2;
 147         } else {
 148                 /* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
 149                 rc = -EINVAL;
 150                 ecryptfs_printk(KERN_WARNING,
 151                                 "Unsupported packet size: [%zd]\n", size);
 152         }
 153         return rc;
 154 }
 155
 156 static int
 157 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
 158                     char **packet, size_t *packet_len)
 159 {
 160         size_t i = 0;
 161         size_t data_len;
 162         size_t packet_size_len;
 163         char *message;
 164         int rc;
 165
 166         /*
 167          *              ***** TAG 64 Packet Format *****
 168          *    | Content Type                       | 1 byte       |
 169          *    | Key Identifier Size                | 1 or 2 bytes |
 170          *    | Key Identifier                     | arbitrary    |
 171          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 172          *    | Encrypted File Encryption Key      | arbitrary    |
 173          */
 174         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
 175                     + session_key->encrypted_key_size);
 176         *packet = kmalloc(data_len, GFP_KERNEL);
 177         message = *packet;
 178         if (!message) {
 179                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 180                 rc = -ENOMEM;
 181                 goto out;
 182         }
 183         message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
 184         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 185                                           &packet_size_len);
 186         if (rc) {
 187                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 188                                 "header; cannot generate packet length\n");
 189                 goto out;
 190         }
 191         i += packet_size_len;
 192         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 193         i += ECRYPTFS_SIG_SIZE_HEX;
 194         rc = ecryptfs_write_packet_length(&message[i],
 195                                           session_key->encrypted_key_size,
 196                                           &packet_size_len);
 197         if (rc) {
 198                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 199                                 "header; cannot generate packet length\n");
 200                 goto out;
 201         }
 202         i += packet_size_len;
 203         memcpy(&message[i], session_key->encrypted_key,
 204                session_key->encrypted_key_size);
 205         i += session_key->encrypted_key_size;
 206         *packet_len = i;
 207 out:
 208         return rc;
 209 }
 210
 211 static int
 212 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
 213                     struct ecryptfs_message *msg)
 214 {
 215         size_t i = 0;
 216         char *data;
 217         size_t data_len;
 218         size_t m_size;
 219         size_t message_len;
 220         u16 checksum = 0;
 221         u16 expected_checksum = 0;
 222         int rc;
 223
 224         /*
 225          *              ***** TAG 65 Packet Format *****
 226          *         | Content Type             | 1 byte       |
 227          *         | Status Indicator         | 1 byte       |
 228          *         | File Encryption Key Size | 1 or 2 bytes |
 229          *         | File Encryption Key      | arbitrary    |
 230          */
 231         message_len = msg->data_len;
 232         data = msg->data;
 233         if (message_len < 4) {
 234                 rc = -EIO;
 235                 goto out;
 236         }
 237         if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
 238                 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
 239                 rc = -EIO;
 240                 goto out;
 241         }
 242         if (data[i++]) {
 243                 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
 244                                 "[%d]\n", data[i-1]);
 245                 rc = -EIO;
 246                 goto out;
 247         }
 248         rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
 249         if (rc) {
 250                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 251                                 "rc = [%d]\n", rc);
 252                 goto out;
 253         }
 254         i += data_len;
 255         if (message_len < (i + m_size)) {
 256                 ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
 257                                 "is shorter than expected\n");
 258                 rc = -EIO;
 259                 goto out;
 260         }
 261         if (m_size < 3) {
 262                 ecryptfs_printk(KERN_ERR,
 263                                 "The decrypted key is not long enough to "
 264                                 "include a cipher code and checksum\n");
 265                 rc = -EIO;
 266                 goto out;
 267         }
 268         *cipher_code = data[i++];
 269         /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
 270         session_key->decrypted_key_size = m_size - 3;
 271         if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
 272                 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
 273                                 "the maximum key size [%d]\n",
 274                                 session_key->decrypted_key_size,
 275                                 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 276                 rc = -EIO;
 277                 goto out;
 278         }
 279         memcpy(session_key->decrypted_key, &data[i],
 280                session_key->decrypted_key_size);
 281         i += session_key->decrypted_key_size;
 282         expected_checksum += (unsigned char)(data[i++]) << 8;
 283         expected_checksum += (unsigned char)(data[i++]);
 284         for (i = 0; i < session_key->decrypted_key_size; i++)
 285                 checksum += session_key->decrypted_key[i];
 286         if (expected_checksum != checksum) {
 287                 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
 288                                 "encryption  key; expected [%x]; calculated "
 289                                 "[%x]\n", expected_checksum, checksum);
 290                 rc = -EIO;
 291         }
 292 out:
 293         return rc;
 294 }
 295
 296
 297 static int
 298 write_tag_66_packet(char *signature, u8 cipher_code,
 299                     struct ecryptfs_crypt_stat *crypt_stat, char **packet,
 300                     size_t *packet_len)
 301 {
 302         size_t i = 0;
 303         size_t j;
 304         size_t data_len;
 305         size_t checksum = 0;
 306         size_t packet_size_len;
 307         char *message;
 308         int rc;
 309
 310         /*
 311          *              ***** TAG 66 Packet Format *****
 312          *         | Content Type             | 1 byte       |
 313          *         | Key Identifier Size      | 1 or 2 bytes |
 314          *         | Key Identifier           | arbitrary    |
 315          *         | File Encryption Key Size | 1 or 2 bytes |
 316          *         | File Encryption Key      | arbitrary    |
 317          */
 318         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
 319         *packet = kmalloc(data_len, GFP_KERNEL);
 320         message = *packet;
 321         if (!message) {
 322                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 323                 rc = -ENOMEM;
 324                 goto out;
 325         }
 326         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
 327         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 328                                           &packet_size_len);
 329         if (rc) {
 330                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 331                                 "header; cannot generate packet length\n");
 332                 goto out;
 333         }
 334         i += packet_size_len;
 335         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 336         i += ECRYPTFS_SIG_SIZE_HEX;
 337         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
 338         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
 339                                           &packet_size_len);
 340         if (rc) {
 341                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 342                                 "header; cannot generate packet length\n");
 343                 goto out;
 344         }
 345         i += packet_size_len;
 346         message[i++] = cipher_code;
 347         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
 348         i += crypt_stat->key_size;
 349         for (j = 0; j < crypt_stat->key_size; j++)
 350                 checksum += crypt_stat->key[j];
 351         message[i++] = (checksum / 256) % 256;
 352         message[i++] = (checksum % 256);
 353         *packet_len = i;
 354 out:
 355         return rc;
 356 }
 357
 358 static int
 359 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
 360                     struct ecryptfs_message *msg)
 361 {
 362         size_t i = 0;
 363         char *data;
 364         size_t data_len;
 365         size_t message_len;
 366         int rc;
 367
 368         /*
 369          *              ***** TAG 65 Packet Format *****
 370          *    | Content Type                       | 1 byte       |
 371          *    | Status Indicator                   | 1 byte       |
 372          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 373          *    | Encrypted File Encryption Key      | arbitrary    |
 374          */
 375         message_len = msg->data_len;
 376         data = msg->data;
 377         /* verify that everything through the encrypted FEK size is present */
 378         if (message_len < 4) {
 379                 rc = -EIO;
 380                 printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
 381                        "message length is [%d]\n", __func__, message_len, 4);
 382                 goto out;
 383         }
 384         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
 385                 rc = -EIO;
 386                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
 387                        __func__);
 388                 goto out;
 389         }
 390         if (data[i++]) {
 391                 rc = -EIO;
 392                 printk(KERN_ERR "%s: Status indicator has non zero "
 393                        "value [%d]\n", __func__, data[i-1]);
 394
 395                 goto out;
 396         }
 397         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
 398                                           &data_len);
 399         if (rc) {
 400                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 401                                 "rc = [%d]\n", rc);
 402                 goto out;
 403         }
 404         i += data_len;
 405         if (message_len < (i + key_rec->enc_key_size)) {
 406                 rc = -EIO;
 407                 printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
 408                        __func__, message_len, (i + key_rec->enc_key_size));
 409                 goto out;
 410         }
 411         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
 412                 rc = -EIO;
 413                 printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
 414                        "the maximum key size [%d]\n", __func__,
 415                        key_rec->enc_key_size,
 416                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 417                 goto out;
 418         }
 419         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
 420 out:
 421         return rc;
 422 }
 423
 424 /**
 425  * ecryptfs_verify_version
 426  * @version: The version number to confirm
 427  *
 428  * Returns zero on good version; non-zero otherwise
 429  */
 430 static int ecryptfs_verify_version(u16 version)
 431 {
 432         int rc = 0;
 433         unsigned char major;
 434         unsigned char minor;
 435
 436         major = ((version >> 8) & 0xFF);
 437         minor = (version & 0xFF);
 438         if (major != ECRYPTFS_VERSION_MAJOR) {
 439                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
 440                                 "Expected [%d]; got [%d]\n",
 441                                 ECRYPTFS_VERSION_MAJOR, major);
 442                 rc = -EINVAL;
 443                 goto out;
 444         }
 445         if (minor != ECRYPTFS_VERSION_MINOR) {
 446                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
 447                                 "Expected [%d]; got [%d]\n",
 448                                 ECRYPTFS_VERSION_MINOR, minor);
 449                 rc = -EINVAL;
 450                 goto out;
 451         }
 452 out:
 453         return rc;
 454 }
 455
 456 /**
 457  * ecryptfs_verify_auth_tok_from_key
 458  * @auth_tok_key: key containing the authentication token
 459  * @auth_tok: authentication token
 460  *
 461  * Returns zero on valid auth tok; -EINVAL otherwise
 462  */
 463 static int
 464 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
 465                                   struct ecryptfs_auth_tok **auth_tok)
 466 {
 467         int rc = 0;
 468
 469         (*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
 470         if (ecryptfs_verify_version((*auth_tok)->version)) {
 471                 printk(KERN_ERR "Data structure version mismatch. Userspace "
 472                        "tools must match eCryptfs kernel module with major "
 473                        "version [%d] and minor version [%d]\n",
 474                        ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
 475                 rc = -EINVAL;
 476                 goto out;
 477         }
 478         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
 479             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
 480                 printk(KERN_ERR "Invalid auth_tok structure "
 481                        "returned from key query\n");
 482                 rc = -EINVAL;
 483                 goto out;
 484         }
 485 out:
 486         return rc;
 487 }
 488
 489 static int
 490 ecryptfs_find_global_auth_tok_for_sig(
 491         struct key **auth_tok_key,
 492         struct ecryptfs_auth_tok **auth_tok,
 493         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
 494 {
 495         struct ecryptfs_global_auth_tok *walker;
 496         int rc = 0;
 497
 498         (*auth_tok_key) = NULL;
 499         (*auth_tok) = NULL;
 500         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 501         list_for_each_entry(walker,
 502                             &mount_crypt_stat->global_auth_tok_list,
 503                             mount_crypt_stat_list) {
 504                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
 505                         continue;
 506
 507                 if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
 508                         rc = -EINVAL;
 509                         goto out;
 510                 }
 511
 512                 rc = key_validate(walker->global_auth_tok_key);
 513                 if (rc) {
 514                         if (rc == -EKEYEXPIRED)
 515                                 goto out;
 516                         goto out_invalid_auth_tok;
 517                 }
 518
 519                 down_write(&(walker->global_auth_tok_key->sem));
 520                 rc = ecryptfs_verify_auth_tok_from_key(
 521                                 walker->global_auth_tok_key, auth_tok);
 522                 if (rc)
 523                         goto out_invalid_auth_tok_unlock;
 524
 525                 (*auth_tok_key) = walker->global_auth_tok_key;
 526                 key_get(*auth_tok_key);
 527                 goto out;
 528         }
 529         rc = -ENOENT;
 530         goto out;
 531 out_invalid_auth_tok_unlock:
 532         up_write(&(walker->global_auth_tok_key->sem));
 533 out_invalid_auth_tok:
 534         printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
 535         walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
 536         key_put(walker->global_auth_tok_key);
 537         walker->global_auth_tok_key = NULL;
 538 out:
 539         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 540         return rc;
 541 }
 542
 543 /**
 544  * ecryptfs_find_auth_tok_for_sig
 545  * @auth_tok: Set to the matching auth_tok; NULL if not found
 546  * @crypt_stat: inode crypt_stat crypto context
 547  * @sig: Sig of auth_tok to find
 548  *
 549  * For now, this function simply looks at the registered auth_tok's
 550  * linked off the mount_crypt_stat, so all the auth_toks that can be
 551  * used must be registered at mount time. This function could
 552  * potentially try a lot harder to find auth_tok's (e.g., by calling
 553  * out to ecryptfsd to dynamically retrieve an auth_tok object) so
 554  * that static registration of auth_tok's will no longer be necessary.
 555  *
 556  * Returns zero on no error; non-zero on error
 557  */
 558 static int
 559 ecryptfs_find_auth_tok_for_sig(
 560         struct key **auth_tok_key,
 561         struct ecryptfs_auth_tok **auth_tok,
 562         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 563         char *sig)
 564 {
 565         int rc = 0;
 566
 567         rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
 568                                                    mount_crypt_stat, sig);
 569         if (rc == -ENOENT) {
 570                 /* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
 571                  * mount_crypt_stat structure, we prevent to use auth toks that
 572                  * are not inserted through the ecryptfs_add_global_auth_tok
 573                  * function.
 574                  */
 575                 if (mount_crypt_stat->flags
 576                                 & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 577                         return -EINVAL;
 578
 579                 rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
 580                                                        sig);
 581         }
 582         return rc;
 583 }
 584
 585 /**
 586  * write_tag_70_packet can gobble a lot of stack space. We stuff most
 587  * of the function's parameters in a kmalloc'd struct to help reduce
 588  * eCryptfs' overall stack usage.
 589  */
 590 struct ecryptfs_write_tag_70_packet_silly_stack {
 591         u8 cipher_code;
 592         size_t max_packet_size;
 593         size_t packet_size_len;
 594         size_t block_aligned_filename_size;
 595         size_t block_size;
 596         size_t i;
 597         size_t j;
 598         size_t num_rand_bytes;
 599         struct mutex *tfm_mutex;
 600         char *block_aligned_filename;
 601         struct ecryptfs_auth_tok *auth_tok;
 602         struct scatterlist src_sg[2];
 603         struct scatterlist dst_sg[2];
 604         struct blkcipher_desc desc;
 605         char iv[ECRYPTFS_MAX_IV_BYTES];
 606         char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 607         char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
 608         struct hash_desc hash_desc;
 609         struct scatterlist hash_sg;
 610 };
 611
 612 /**
 613  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
 614  * @filename: NULL-terminated filename string
 615  *
 616  * This is the simplest mechanism for achieving filename encryption in
 617  * eCryptfs. It encrypts the given filename with the mount-wide
 618  * filename encryption key (FNEK) and stores it in a packet to @dest,
 619  * which the callee will encode and write directly into the dentry
 620  * name.
 621  */
 622 int
 623 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 624                              size_t *packet_size,
 625                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 626                              char *filename, size_t filename_size)
 627 {
 628         struct ecryptfs_write_tag_70_packet_silly_stack *s;
 629         struct key *auth_tok_key = NULL;
 630         int rc = 0;
 631
 632         s = kmalloc(sizeof(*s), GFP_KERNEL);
 633         if (!s) {
 634                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 635                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
 636                 rc = -ENOMEM;
 637                 goto out;
 638         }
 639         s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 640         (*packet_size) = 0;
 641         rc = ecryptfs_find_auth_tok_for_sig(
 642                 &auth_tok_key,
 643                 &s->auth_tok, mount_crypt_stat,
 644                 mount_crypt_stat->global_default_fnek_sig);
 645         if (rc) {
 646                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 647                        "fnek sig [%s]; rc = [%d]\n", __func__,
 648                        mount_crypt_stat->global_default_fnek_sig, rc);
 649                 goto out;
 650         }
 651         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
 652                 &s->desc.tfm,
 653                 &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
 654         if (unlikely(rc)) {
 655                 printk(KERN_ERR "Internal error whilst attempting to get "
 656                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
 657                        mount_crypt_stat->global_default_fn_cipher_name, rc);
 658                 goto out;
 659         }
 660         mutex_lock(s->tfm_mutex);
 661         s->block_size = crypto_blkcipher_blocksize(s->desc.tfm);
 662         /* Plus one for the \0 separator between the random prefix
 663          * and the plaintext filename */
 664         s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
 665         s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
 666         if ((s->block_aligned_filename_size % s->block_size) != 0) {
 667                 s->num_rand_bytes += (s->block_size
 668                                       - (s->block_aligned_filename_size
 669                                          % s->block_size));
 670                 s->block_aligned_filename_size = (s->num_rand_bytes
 671                                                   + filename_size);
 672         }
 673         /* Octet 0: Tag 70 identifier
 674          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 675          *              and block-aligned encrypted filename size)
 676          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 677          * Octet N2-N3: Cipher identifier (1 octet)
 678          * Octets N3-N4: Block-aligned encrypted filename
 679          *  - Consists of a minimum number of random characters, a \0
 680          *    separator, and then the filename */
 681         s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
 682                               + s->block_aligned_filename_size);
 683         if (dest == NULL) {
 684                 (*packet_size) = s->max_packet_size;
 685                 goto out_unlock;
 686         }
 687         if (s->max_packet_size > (*remaining_bytes)) {
 688                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
 689                        "[%zd] available\n", __func__, s->max_packet_size,
 690                        (*remaining_bytes));
 691                 rc = -EINVAL;
 692                 goto out_unlock;
 693         }
 694         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
 695                                             GFP_KERNEL);
 696         if (!s->block_aligned_filename) {
 697                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
 698                        "kzalloc [%zd] bytes\n", __func__,
 699                        s->block_aligned_filename_size);
 700                 rc = -ENOMEM;
 701                 goto out_unlock;
 702         }
 703         s->i = 0;
 704         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
 705         rc = ecryptfs_write_packet_length(&dest[s->i],
 706                                           (ECRYPTFS_SIG_SIZE
 707                                            + 1 /* Cipher code */
 708                                            + s->block_aligned_filename_size),
 709                                           &s->packet_size_len);
 710         if (rc) {
 711                 printk(KERN_ERR "%s: Error generating tag 70 packet "
 712                        "header; cannot generate packet length; rc = [%d]\n",
 713                        __func__, rc);
 714                 goto out_free_unlock;
 715         }
 716         s->i += s->packet_size_len;
 717         ecryptfs_from_hex(&dest[s->i],
 718                           mount_crypt_stat->global_default_fnek_sig,
 719                           ECRYPTFS_SIG_SIZE);
 720         s->i += ECRYPTFS_SIG_SIZE;
 721         s->cipher_code = ecryptfs_code_for_cipher_string(
 722                 mount_crypt_stat->global_default_fn_cipher_name,
 723                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 724         if (s->cipher_code == 0) {
 725                 printk(KERN_WARNING "%s: Unable to generate code for "
 726                        "cipher [%s] with key bytes [%zd]\n", __func__,
 727                        mount_crypt_stat->global_default_fn_cipher_name,
 728                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 729                 rc = -EINVAL;
 730                 goto out_free_unlock;
 731         }
 732         dest[s->i++] = s->cipher_code;
 733         /* TODO: Support other key modules than passphrase for
 734          * filename encryption */
 735         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
 736                 rc = -EOPNOTSUPP;
 737                 printk(KERN_INFO "%s: Filename encryption only supports "
 738                        "password tokens\n", __func__);
 739                 goto out_free_unlock;
 740         }
 741         sg_init_one(
 742                 &s->hash_sg,
 743                 (u8 *)s->auth_tok->token.password.session_key_encryption_key,
 744                 s->auth_tok->token.password.session_key_encryption_key_bytes);
 745         s->hash_desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 746         s->hash_desc.tfm = crypto_alloc_hash(ECRYPTFS_TAG_70_DIGEST, 0,
 747                                              CRYPTO_ALG_ASYNC);
 748         if (IS_ERR(s->hash_desc.tfm)) {
 749                         rc = PTR_ERR(s->hash_desc.tfm);
 750                         printk(KERN_ERR "%s: Error attempting to "
 751                                "allocate hash crypto context; rc = [%d]\n",
 752                                __func__, rc);
 753                         goto out_free_unlock;
 754         }
 755         rc = crypto_hash_init(&s->hash_desc);
 756         if (rc) {
 757                 printk(KERN_ERR
 758                        "%s: Error initializing crypto hash; rc = [%d]\n",
 759                        __func__, rc);
 760                 goto out_release_free_unlock;
 761         }
 762         rc = crypto_hash_update(
 763                 &s->hash_desc, &s->hash_sg,
 764                 s->auth_tok->token.password.session_key_encryption_key_bytes);
 765         if (rc) {
 766                 printk(KERN_ERR
 767                        "%s: Error updating crypto hash; rc = [%d]\n",
 768                        __func__, rc);
 769                 goto out_release_free_unlock;
 770         }
 771         rc = crypto_hash_final(&s->hash_desc, s->hash);
 772         if (rc) {
 773                 printk(KERN_ERR
 774                        "%s: Error finalizing crypto hash; rc = [%d]\n",
 775                        __func__, rc);
 776                 goto out_release_free_unlock;
 777         }
 778         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
 779                 s->block_aligned_filename[s->j] =
 780                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
 781                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
 782                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
 783                         sg_init_one(&s->hash_sg, (u8 *)s->hash,
 784                                     ECRYPTFS_TAG_70_DIGEST_SIZE);
 785                         rc = crypto_hash_init(&s->hash_desc);
 786                         if (rc) {
 787                                 printk(KERN_ERR
 788                                        "%s: Error initializing crypto hash; "
 789                                        "rc = [%d]\n", __func__, rc);
 790                                 goto out_release_free_unlock;
 791                         }
 792                         rc = crypto_hash_update(&s->hash_desc, &s->hash_sg,
 793                                                 ECRYPTFS_TAG_70_DIGEST_SIZE);
 794                         if (rc) {
 795                                 printk(KERN_ERR
 796                                        "%s: Error updating crypto hash; "
 797                                        "rc = [%d]\n", __func__, rc);
 798                                 goto out_release_free_unlock;
 799                         }
 800                         rc = crypto_hash_final(&s->hash_desc, s->tmp_hash);
 801                         if (rc) {
 802                                 printk(KERN_ERR
 803                                        "%s: Error finalizing crypto hash; "
 804                                        "rc = [%d]\n", __func__, rc);
 805                                 goto out_release_free_unlock;
 806                         }
 807                         memcpy(s->hash, s->tmp_hash,
 808                                ECRYPTFS_TAG_70_DIGEST_SIZE);
 809                 }
 810                 if (s->block_aligned_filename[s->j] == '\0')
 811                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
 812         }
 813         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 814                filename_size);
 815         rc = virt_to_scatterlist(s->block_aligned_filename,
 816                                  s->block_aligned_filename_size, s->src_sg, 2);
 817         if (rc < 1) {
 818                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 819                        "convert filename memory to scatterlist; rc = [%d]. "
 820                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 821                        s->block_aligned_filename_size);
 822                 goto out_release_free_unlock;
 823         }
 824         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
 825                                  s->dst_sg, 2);
 826         if (rc < 1) {
 827                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 828                        "convert encrypted filename memory to scatterlist; "
 829                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 830                        __func__, rc, s->block_aligned_filename_size);
 831                 goto out_release_free_unlock;
 832         }
 833         /* The characters in the first block effectively do the job
 834          * of the IV here, so we just use 0's for the IV. Note the
 835          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
 836          * >= ECRYPTFS_MAX_IV_BYTES. */
 837         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
 838         s->desc.info = s->iv;
 839         rc = crypto_blkcipher_setkey(
 840                 s->desc.tfm,
 841                 s->auth_tok->token.password.session_key_encryption_key,
 842                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 843         if (rc < 0) {
 844                 printk(KERN_ERR "%s: Error setting key for crypto context; "
 845                        "rc = [%d]. s->auth_tok->token.password.session_key_"
 846                        "encryption_key = [0x%p]; mount_crypt_stat->"
 847                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
 848                        rc,
 849                        s->auth_tok->token.password.session_key_encryption_key,
 850                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 851                 goto out_release_free_unlock;
 852         }
 853         rc = crypto_blkcipher_encrypt_iv(&s->desc, s->dst_sg, s->src_sg,
 854                                          s->block_aligned_filename_size);
 855         if (rc) {
 856                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
 857                        "rc = [%d]\n", __func__, rc);
 858                 goto out_release_free_unlock;
 859         }
 860         s->i += s->block_aligned_filename_size;
 861         (*packet_size) = s->i;
 862         (*remaining_bytes) -= (*packet_size);
 863 out_release_free_unlock:
 864         crypto_free_hash(s->hash_desc.tfm);
 865 out_free_unlock:
 866         kzfree(s->block_aligned_filename);
 867 out_unlock:
 868         mutex_unlock(s->tfm_mutex);
 869 out:
 870         if (auth_tok_key) {
 871                 up_write(&(auth_tok_key->sem));
 872                 key_put(auth_tok_key);
 873         }
 874         kfree(s);
 875         return rc;
 876 }
 877
 878 struct ecryptfs_parse_tag_70_packet_silly_stack {
 879         u8 cipher_code;
 880         size_t max_packet_size;
 881         size_t packet_size_len;
 882         size_t parsed_tag_70_packet_size;
 883         size_t block_aligned_filename_size;
 884         size_t block_size;
 885         size_t i;
 886         struct mutex *tfm_mutex;
 887         char *decrypted_filename;
 888         struct ecryptfs_auth_tok *auth_tok;
 889         struct scatterlist src_sg[2];
 890         struct scatterlist dst_sg[2];
 891         struct blkcipher_desc desc;
 892         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 893         char iv[ECRYPTFS_MAX_IV_BYTES];
 894         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
 895 };
 896
 897 /**
 898  * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 899  * @filename: This function kmalloc's the memory for the filename
 900  * @filename_size: This function sets this to the amount of memory
 901  *                 kmalloc'd for the filename
 902  * @packet_size: This function sets this to the the number of octets
 903  *               in the packet parsed
 904  * @mount_crypt_stat: The mount-wide cryptographic context
 905  * @data: The memory location containing the start of the tag 70
 906  *        packet
 907  * @max_packet_size: The maximum legal size of the packet to be parsed
 908  *                   from @data
 909  *
 910  * Returns zero on success; non-zero otherwise
 911  */
 912 int
 913 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 914                              size_t *packet_size,
 915                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 916                              char *data, size_t max_packet_size)
 917 {
 918         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
 919         struct key *auth_tok_key = NULL;
 920         int rc = 0;
 921
 922         (*packet_size) = 0;
 923         (*filename_size) = 0;
 924         (*filename) = NULL;
 925         s = kmalloc(sizeof(*s), GFP_KERNEL);
 926         if (!s) {
 927                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 928                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
 929                 rc = -ENOMEM;
 930                 goto out;
 931         }
 932         s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 933         if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
 934                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
 935                        "at least [%d]\n", __func__, max_packet_size,
 936                        ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
 937                 rc = -EINVAL;
 938                 goto out;
 939         }
 940         /* Octet 0: Tag 70 identifier
 941          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 942          *              and block-aligned encrypted filename size)
 943          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 944          * Octet N2-N3: Cipher identifier (1 octet)
 945          * Octets N3-N4: Block-aligned encrypted filename
 946          *  - Consists of a minimum number of random numbers, a \0
 947          *    separator, and then the filename */
 948         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
 949                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
 950                        "tag [0x%.2x]\n", __func__,
 951                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
 952                 rc = -EINVAL;
 953                 goto out;
 954         }
 955         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
 956                                           &s->parsed_tag_70_packet_size,
 957                                           &s->packet_size_len);
 958         if (rc) {
 959                 printk(KERN_WARNING "%s: Error parsing packet length; "
 960                        "rc = [%d]\n", __func__, rc);
 961                 goto out;
 962         }
 963         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
 964                                           - ECRYPTFS_SIG_SIZE - 1);
 965         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
 966             > max_packet_size) {
 967                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
 968                        "size is [%zd]\n", __func__, max_packet_size,
 969                        (1 + s->packet_size_len + 1
 970                         + s->block_aligned_filename_size));
 971                 rc = -EINVAL;
 972                 goto out;
 973         }
 974         (*packet_size) += s->packet_size_len;
 975         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
 976                         ECRYPTFS_SIG_SIZE);
 977         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 978         (*packet_size) += ECRYPTFS_SIG_SIZE;
 979         s->cipher_code = data[(*packet_size)++];
 980         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
 981         if (rc) {
 982                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
 983                        __func__, s->cipher_code);
 984                 goto out;
 985         }
 986         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
 987                                             &s->auth_tok, mount_crypt_stat,
 988                                             s->fnek_sig_hex);
 989         if (rc) {
 990                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 991                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
 992                        rc);
 993                 goto out;
 994         }
 995         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->desc.tfm,
 996                                                         &s->tfm_mutex,
 997                                                         s->cipher_string);
 998         if (unlikely(rc)) {
 999                 printk(KERN_ERR "Internal error whilst attempting to get "
1000                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1001                        s->cipher_string, rc);
1002                 goto out;
1003         }
1004         mutex_lock(s->tfm_mutex);
1005         rc = virt_to_scatterlist(&data[(*packet_size)],
1006                                  s->block_aligned_filename_size, s->src_sg, 2);
1007         if (rc < 1) {
1008                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1009                        "convert encrypted filename memory to scatterlist; "
1010                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1011                        __func__, rc, s->block_aligned_filename_size);
1012                 goto out_unlock;
1013         }
1014         (*packet_size) += s->block_aligned_filename_size;
1015         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
1016                                         GFP_KERNEL);
1017         if (!s->decrypted_filename) {
1018                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1019                        "kmalloc [%zd] bytes\n", __func__,
1020                        s->block_aligned_filename_size);
1021                 rc = -ENOMEM;
1022                 goto out_unlock;
1023         }
1024         rc = virt_to_scatterlist(s->decrypted_filename,
1025                                  s->block_aligned_filename_size, s->dst_sg, 2);
1026         if (rc < 1) {
1027                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1028                        "convert decrypted filename memory to scatterlist; "
1029                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1030                        __func__, rc, s->block_aligned_filename_size);
1031                 goto out_free_unlock;
1032         }
1033         /* The characters in the first block effectively do the job of
1034          * the IV here, so we just use 0's for the IV. Note the
1035          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1036          * >= ECRYPTFS_MAX_IV_BYTES. */
1037         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
1038         s->desc.info = s->iv;
1039         /* TODO: Support other key modules than passphrase for
1040          * filename encryption */
1041         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1042                 rc = -EOPNOTSUPP;
1043                 printk(KERN_INFO "%s: Filename encryption only supports "
1044                        "password tokens\n", __func__);
1045                 goto out_free_unlock;
1046         }
1047         rc = crypto_blkcipher_setkey(
1048                 s->desc.tfm,
1049                 s->auth_tok->token.password.session_key_encryption_key,
1050                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1051         if (rc < 0) {
1052                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1053                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1054                        "encryption_key = [0x%p]; mount_crypt_stat->"
1055                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1056                        rc,
1057                        s->auth_tok->token.password.session_key_encryption_key,
1058                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1059                 goto out_free_unlock;
1060         }
1061         rc = crypto_blkcipher_decrypt_iv(&s->desc, s->dst_sg, s->src_sg,
1062                                          s->block_aligned_filename_size);
1063         if (rc) {
1064                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1065                        "rc = [%d]\n", __func__, rc);
1066                 goto out_free_unlock;
1067         }
1068         s->i = 0;
1069         while (s->decrypted_filename[s->i] != '\0'
1070                && s->i < s->block_aligned_filename_size)
1071                 s->i++;
1072         if (s->i == s->block_aligned_filename_size) {
1073                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1074                        "find valid separator between random characters and "
1075                        "the filename\n", __func__);
1076                 rc = -EINVAL;
1077                 goto out_free_unlock;
1078         }
1079         s->i++;
1080         (*filename_size) = (s->block_aligned_filename_size - s->i);
1081         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1082                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1083                        "invalid\n", __func__, (*filename_size));
1084                 rc = -EINVAL;
1085                 goto out_free_unlock;
1086         }
1087         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1088         if (!(*filename)) {
1089                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1090                        "kmalloc [%zd] bytes\n", __func__,
1091                        ((*filename_size) + 1));
1092                 rc = -ENOMEM;
1093                 goto out_free_unlock;
1094         }
1095         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1096         (*filename)[(*filename_size)] = '\0';
1097 out_free_unlock:
1098         kfree(s->decrypted_filename);
1099 out_unlock:
1100         mutex_unlock(s->tfm_mutex);
1101 out:
1102         if (rc) {
1103                 (*packet_size) = 0;
1104                 (*filename_size) = 0;
1105                 (*filename) = NULL;
1106         }
1107         if (auth_tok_key) {
1108                 up_write(&(auth_tok_key->sem));
1109                 key_put(auth_tok_key);
1110         }
1111         kfree(s);
1112         return rc;
1113 }
1114
1115 static int
1116 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1117 {
1118         int rc = 0;
1119
1120         (*sig) = NULL;
1121         switch (auth_tok->token_type) {
1122         case ECRYPTFS_PASSWORD:
1123                 (*sig) = auth_tok->token.password.signature;
1124                 break;
1125         case ECRYPTFS_PRIVATE_KEY:
1126                 (*sig) = auth_tok->token.private_key.signature;
1127                 break;
1128         default:
1129                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1130                        auth_tok->token_type);
1131                 rc = -EINVAL;
1132         }
1133         return rc;
1134 }
1135
1136 /**
1137  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1138  * @auth_tok: The key authentication token used to decrypt the session key
1139  * @crypt_stat: The cryptographic context
1140  *
1141  * Returns zero on success; non-zero error otherwise.
1142  */
1143 static int
1144 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1145                                   struct ecryptfs_crypt_stat *crypt_stat)
1146 {
1147         u8 cipher_code = 0;
1148         struct ecryptfs_msg_ctx *msg_ctx;
1149         struct ecryptfs_message *msg = NULL;
1150         char *auth_tok_sig;
1151         char *payload = NULL;
1152         size_t payload_len = 0;
1153         int rc;
1154
1155         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1156         if (rc) {
1157                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1158                        auth_tok->token_type);
1159                 goto out;
1160         }
1161         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1162                                  &payload, &payload_len);
1163         if (rc) {
1164                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1165                 goto out;
1166         }
1167         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1168         if (rc) {
1169                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1170                                 "ecryptfsd: %d\n", rc);
1171                 goto out;
1172         }
1173         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1174         if (rc) {
1175                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1176                                 "from the user space daemon\n");
1177                 rc = -EIO;
1178                 goto out;
1179         }
1180         rc = parse_tag_65_packet(&(auth_tok->session_key),
1181                                  &cipher_code, msg);
1182         if (rc) {
1183                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1184                        rc);
1185                 goto out;
1186         }
1187         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1188         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1189                auth_tok->session_key.decrypted_key_size);
1190         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1191         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1192         if (rc) {
1193                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1194                                 cipher_code)
1195                 goto out;
1196         }
1197         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1198         if (ecryptfs_verbosity > 0) {
1199                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1200                 ecryptfs_dump_hex(crypt_stat->key,
1201                                   crypt_stat->key_size);
1202         }
1203 out:
1204         kfree(msg);
1205         kfree(payload);
1206         return rc;
1207 }
1208
1209 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1210 {
1211         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1212         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1213
1214         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1215                                  auth_tok_list_head, list) {
1216                 list_del(&auth_tok_list_item->list);
1217                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1218                                 auth_tok_list_item);
1219         }
1220 }
1221
1222 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1223
1224 /**
1225  * parse_tag_1_packet
1226  * @crypt_stat: The cryptographic context to modify based on packet contents
1227  * @data: The raw bytes of the packet.
1228  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1229  *                 a new authentication token will be placed at the
1230  *                 end of this list for this packet.
1231  * @new_auth_tok: Pointer to a pointer to memory that this function
1232  *                allocates; sets the memory address of the pointer to
1233  *                NULL on error. This object is added to the
1234  *                auth_tok_list.
1235  * @packet_size: This function writes the size of the parsed packet
1236  *               into this memory location; zero on error.
1237  * @max_packet_size: The maximum allowable packet size
1238  *
1239  * Returns zero on success; non-zero on error.
1240  */
1241 static int
1242 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1243                    unsigned char *data, struct list_head *auth_tok_list,
1244                    struct ecryptfs_auth_tok **new_auth_tok,
1245                    size_t *packet_size, size_t max_packet_size)
1246 {
1247         size_t body_size;
1248         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1249         size_t length_size;
1250         int rc = 0;
1251
1252         (*packet_size) = 0;
1253         (*new_auth_tok) = NULL;
1254         /**
1255          * This format is inspired by OpenPGP; see RFC 2440
1256          * packet tag 1
1257          *
1258          * Tag 1 identifier (1 byte)
1259          * Max Tag 1 packet size (max 3 bytes)
1260          * Version (1 byte)
1261          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1262          * Cipher identifier (1 byte)
1263          * Encrypted key size (arbitrary)
1264          *
1265          * 12 bytes minimum packet size
1266          */
1267         if (unlikely(max_packet_size < 12)) {
1268                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1269                 rc = -EINVAL;
1270                 goto out;
1271         }
1272         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1273                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1274                        ECRYPTFS_TAG_1_PACKET_TYPE);
1275                 rc = -EINVAL;
1276                 goto out;
1277         }
1278         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1279          * at end of function upon failure */
1280         auth_tok_list_item =
1281                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1282                                   GFP_KERNEL);
1283         if (!auth_tok_list_item) {
1284                 printk(KERN_ERR "Unable to allocate memory\n");
1285                 rc = -ENOMEM;
1286                 goto out;
1287         }
1288         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1289         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1290                                           &length_size);
1291         if (rc) {
1292                 printk(KERN_WARNING "Error parsing packet length; "
1293                        "rc = [%d]\n", rc);
1294                 goto out_free;
1295         }
1296         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1297                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1298                 rc = -EINVAL;
1299                 goto out_free;
1300         }
1301         (*packet_size) += length_size;
1302         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1303                 printk(KERN_WARNING "Packet size exceeds max\n");
1304                 rc = -EINVAL;
1305                 goto out_free;
1306         }
1307         if (unlikely(data[(*packet_size)++] != 0x03)) {
1308                 printk(KERN_WARNING "Unknown version number [%d]\n",
1309                        data[(*packet_size) - 1]);
1310                 rc = -EINVAL;
1311                 goto out_free;
1312         }
1313         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1314                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1315         *packet_size += ECRYPTFS_SIG_SIZE;
1316         /* This byte is skipped because the kernel does not need to
1317          * know which public key encryption algorithm was used */
1318         (*packet_size)++;
1319         (*new_auth_tok)->session_key.encrypted_key_size =
1320                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1321         if ((*new_auth_tok)->session_key.encrypted_key_size
1322             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1323                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1324                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
1325                 rc = -EINVAL;
1326                 goto out;
1327         }
1328         memcpy((*new_auth_tok)->session_key.encrypted_key,
1329                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1330         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1331         (*new_auth_tok)->session_key.flags &=
1332                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1333         (*new_auth_tok)->session_key.flags |=
1334                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1335         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1336         (*new_auth_tok)->flags = 0;
1337         (*new_auth_tok)->session_key.flags &=
1338                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1339         (*new_auth_tok)->session_key.flags &=
1340                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1341         list_add(&auth_tok_list_item->list, auth_tok_list);
1342         goto out;
1343 out_free:
1344         (*new_auth_tok) = NULL;
1345         memset(auth_tok_list_item, 0,
1346                sizeof(struct ecryptfs_auth_tok_list_item));
1347         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1348                         auth_tok_list_item);
1349 out:
1350         if (rc)
1351                 (*packet_size) = 0;
1352         return rc;
1353 }
1354
1355 /**
1356  * parse_tag_3_packet
1357  * @crypt_stat: The cryptographic context to modify based on packet
1358  *              contents.
1359  * @data: The raw bytes of the packet.
1360  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1361  *                 a new authentication token will be placed at the end
1362  *                 of this list for this packet.
1363  * @new_auth_tok: Pointer to a pointer to memory that this function
1364  *                allocates; sets the memory address of the pointer to
1365  *                NULL on error. This object is added to the
1366  *                auth_tok_list.
1367  * @packet_size: This function writes the size of the parsed packet
1368  *               into this memory location; zero on error.
1369  * @max_packet_size: maximum number of bytes to parse
1370  *
1371  * Returns zero on success; non-zero on error.
1372  */
1373 static int
1374 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1375                    unsigned char *data, struct list_head *auth_tok_list,
1376                    struct ecryptfs_auth_tok **new_auth_tok,
1377                    size_t *packet_size, size_t max_packet_size)
1378 {
1379         size_t body_size;
1380         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1381         size_t length_size;
1382         int rc = 0;
1383
1384         (*packet_size) = 0;
1385         (*new_auth_tok) = NULL;
1386         /**
1387          *This format is inspired by OpenPGP; see RFC 2440
1388          * packet tag 3
1389          *
1390          * Tag 3 identifier (1 byte)
1391          * Max Tag 3 packet size (max 3 bytes)
1392          * Version (1 byte)
1393          * Cipher code (1 byte)
1394          * S2K specifier (1 byte)
1395          * Hash identifier (1 byte)
1396          * Salt (ECRYPTFS_SALT_SIZE)
1397          * Hash iterations (1 byte)
1398          * Encrypted key (arbitrary)
1399          *
1400          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1401          */
1402         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1403                 printk(KERN_ERR "Max packet size too large\n");
1404                 rc = -EINVAL;
1405                 goto out;
1406         }
1407         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1408                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1409                        ECRYPTFS_TAG_3_PACKET_TYPE);
1410                 rc = -EINVAL;
1411                 goto out;
1412         }
1413         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1414          * at end of function upon failure */
1415         auth_tok_list_item =
1416             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1417         if (!auth_tok_list_item) {
1418                 printk(KERN_ERR "Unable to allocate memory\n");
1419                 rc = -ENOMEM;
1420                 goto out;
1421         }
1422         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1423         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1424                                           &length_size);
1425         if (rc) {
1426                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1427                        rc);
1428                 goto out_free;
1429         }
1430         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1431                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1432                 rc = -EINVAL;
1433                 goto out_free;
1434         }
1435         (*packet_size) += length_size;
1436         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1437                 printk(KERN_ERR "Packet size exceeds max\n");
1438                 rc = -EINVAL;
1439                 goto out_free;
1440         }
1441         (*new_auth_tok)->session_key.encrypted_key_size =
1442                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1443         if ((*new_auth_tok)->session_key.encrypted_key_size
1444             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1445                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1446                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1447                 rc = -EINVAL;
1448                 goto out_free;
1449         }
1450         if (unlikely(data[(*packet_size)++] != 0x04)) {
1451                 printk(KERN_WARNING "Unknown version number [%d]\n",
1452                        data[(*packet_size) - 1]);
1453                 rc = -EINVAL;
1454                 goto out_free;
1455         }
1456         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1457                                             (u16)data[(*packet_size)]);
1458         if (rc)
1459                 goto out_free;
1460         /* A little extra work to differentiate among the AES key
1461          * sizes; see RFC2440 */
1462         switch(data[(*packet_size)++]) {
1463         case RFC2440_CIPHER_AES_192:
1464                 crypt_stat->key_size = 24;
1465                 break;
1466         default:
1467                 crypt_stat->key_size =
1468                         (*new_auth_tok)->session_key.encrypted_key_size;
1469         }
1470         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1471         if (rc)
1472                 goto out_free;
1473         if (unlikely(data[(*packet_size)++] != 0x03)) {
1474                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1475                 rc = -ENOSYS;
1476                 goto out_free;
1477         }
1478         /* TODO: finish the hash mapping */
1479         switch (data[(*packet_size)++]) {
1480         case 0x01: /* See RFC2440 for these numbers and their mappings */
1481                 /* Choose MD5 */
1482                 memcpy((*new_auth_tok)->token.password.salt,
1483                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1484                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1485                 /* This conversion was taken straight from RFC2440 */
1486                 (*new_auth_tok)->token.password.hash_iterations =
1487                         ((u32) 16 + (data[(*packet_size)] & 15))
1488                                 << ((data[(*packet_size)] >> 4) + 6);
1489                 (*packet_size)++;
1490                 /* Friendly reminder:
1491                  * (*new_auth_tok)->session_key.encrypted_key_size =
1492                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1493                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1494                        &data[(*packet_size)],
1495                        (*new_auth_tok)->session_key.encrypted_key_size);
1496                 (*packet_size) +=
1497                         (*new_auth_tok)->session_key.encrypted_key_size;
1498                 (*new_auth_tok)->session_key.flags &=
1499                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1500                 (*new_auth_tok)->session_key.flags |=
1501                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1502                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1503                 break;
1504         default:
1505                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1506                                 "[%d]\n", data[(*packet_size) - 1]);
1507                 rc = -ENOSYS;
1508                 goto out_free;
1509         }
1510         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1511         /* TODO: Parametarize; we might actually want userspace to
1512          * decrypt the session key. */
1513         (*new_auth_tok)->session_key.flags &=
1514                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1515         (*new_auth_tok)->session_key.flags &=
1516                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1517         list_add(&auth_tok_list_item->list, auth_tok_list);
1518         goto out;
1519 out_free:
1520         (*new_auth_tok) = NULL;
1521         memset(auth_tok_list_item, 0,
1522                sizeof(struct ecryptfs_auth_tok_list_item));
1523         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1524                         auth_tok_list_item);
1525 out:
1526         if (rc)
1527                 (*packet_size) = 0;
1528         return rc;
1529 }
1530
1531 /**
1532  * parse_tag_11_packet
1533  * @data: The raw bytes of the packet
1534  * @contents: This function writes the data contents of the literal
1535  *            packet into this memory location
1536  * @max_contents_bytes: The maximum number of bytes that this function
1537  *                      is allowed to write into contents
1538  * @tag_11_contents_size: This function writes the size of the parsed
1539  *                        contents into this memory location; zero on
1540  *                        error
1541  * @packet_size: This function writes the size of the parsed packet
1542  *               into this memory location; zero on error
1543  * @max_packet_size: maximum number of bytes to parse
1544  *
1545  * Returns zero on success; non-zero on error.
1546  */
1547 static int
1548 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1549                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1550                     size_t *packet_size, size_t max_packet_size)
1551 {
1552         size_t body_size;
1553         size_t length_size;
1554         int rc = 0;
1555
1556         (*packet_size) = 0;
1557         (*tag_11_contents_size) = 0;
1558         /* This format is inspired by OpenPGP; see RFC 2440
1559          * packet tag 11
1560          *
1561          * Tag 11 identifier (1 byte)
1562          * Max Tag 11 packet size (max 3 bytes)
1563          * Binary format specifier (1 byte)
1564          * Filename length (1 byte)
1565          * Filename ("_CONSOLE") (8 bytes)
1566          * Modification date (4 bytes)
1567          * Literal data (arbitrary)
1568          *
1569          * We need at least 16 bytes of data for the packet to even be
1570          * valid.
1571          */
1572         if (max_packet_size < 16) {
1573                 printk(KERN_ERR "Maximum packet size too small\n");
1574                 rc = -EINVAL;
1575                 goto out;
1576         }
1577         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1578                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1579                 rc = -EINVAL;
1580                 goto out;
1581         }
1582         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1583                                           &length_size);
1584         if (rc) {
1585                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1586                 goto out;
1587         }
1588         if (body_size < 14) {
1589                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1590                 rc = -EINVAL;
1591                 goto out;
1592         }
1593         (*packet_size) += length_size;
1594         (*tag_11_contents_size) = (body_size - 14);
1595         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1596                 printk(KERN_ERR "Packet size exceeds max\n");
1597                 rc = -EINVAL;
1598                 goto out;
1599         }
1600         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1601                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1602                        "expected size\n");
1603                 rc = -EINVAL;
1604                 goto out;
1605         }
1606         if (data[(*packet_size)++] != 0x62) {
1607                 printk(KERN_WARNING "Unrecognizable packet\n");
1608                 rc = -EINVAL;
1609                 goto out;
1610         }
1611         if (data[(*packet_size)++] != 0x08) {
1612                 printk(KERN_WARNING "Unrecognizable packet\n");
1613                 rc = -EINVAL;
1614                 goto out;
1615         }
1616         (*packet_size) += 12; /* Ignore filename and modification date */
1617         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1618         (*packet_size) += (*tag_11_contents_size);
1619 out:
1620         if (rc) {
1621                 (*packet_size) = 0;
1622                 (*tag_11_contents_size) = 0;
1623         }
1624         return rc;
1625 }
1626
1627 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1628                                       struct ecryptfs_auth_tok **auth_tok,
1629                                       char *sig)
1630 {
1631         int rc = 0;
1632
1633         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1634         if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1635                 (*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1636                 if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1637                         printk(KERN_ERR "Could not find key with description: [%s]\n",
1638                               sig);
1639                         rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1640                         (*auth_tok_key) = NULL;
1641                         goto out;
1642                 }
1643         }
1644         down_write(&(*auth_tok_key)->sem);
1645         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1646         if (rc) {
1647                 up_write(&(*auth_tok_key)->sem);
1648                 key_put(*auth_tok_key);
1649                 (*auth_tok_key) = NULL;
1650                 goto out;
1651         }
1652 out:
1653         return rc;
1654 }
1655
1656 /**
1657  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1658  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1659  * @crypt_stat: The cryptographic context
1660  *
1661  * Returns zero on success; non-zero error otherwise
1662  */
1663 static int
1664 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1665                                          struct ecryptfs_crypt_stat *crypt_stat)
1666 {
1667         struct scatterlist dst_sg[2];
1668         struct scatterlist src_sg[2];
1669         struct mutex *tfm_mutex;
1670         struct blkcipher_desc desc = {
1671                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
1672         };
1673         int rc = 0;
1674
1675         if (unlikely(ecryptfs_verbosity > 0)) {
1676                 ecryptfs_printk(
1677                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1678                         auth_tok->token.password.session_key_encryption_key_bytes);
1679                 ecryptfs_dump_hex(
1680                         auth_tok->token.password.session_key_encryption_key,
1681                         auth_tok->token.password.session_key_encryption_key_bytes);
1682         }
1683         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
1684                                                         crypt_stat->cipher);
1685         if (unlikely(rc)) {
1686                 printk(KERN_ERR "Internal error whilst attempting to get "
1687                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1688                        crypt_stat->cipher, rc);
1689                 goto out;
1690         }
1691         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1692                                  auth_tok->session_key.encrypted_key_size,
1693                                  src_sg, 2);
1694         if (rc < 1 || rc > 2) {
1695                 printk(KERN_ERR "Internal error whilst attempting to convert "
1696                         "auth_tok->session_key.encrypted_key to scatterlist; "
1697                         "expected rc = 1; got rc = [%d]. "
1698                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1699                         auth_tok->session_key.encrypted_key_size);
1700                 goto out;
1701         }
1702         auth_tok->session_key.decrypted_key_size =
1703                 auth_tok->session_key.encrypted_key_size;
1704         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1705                                  auth_tok->session_key.decrypted_key_size,
1706                                  dst_sg, 2);
1707         if (rc < 1 || rc > 2) {
1708                 printk(KERN_ERR "Internal error whilst attempting to convert "
1709                         "auth_tok->session_key.decrypted_key to scatterlist; "
1710                         "expected rc = 1; got rc = [%d]\n", rc);
1711                 goto out;
1712         }
1713         mutex_lock(tfm_mutex);
1714         rc = crypto_blkcipher_setkey(
1715                 desc.tfm, auth_tok->token.password.session_key_encryption_key,
1716                 crypt_stat->key_size);
1717         if (unlikely(rc < 0)) {
1718                 mutex_unlock(tfm_mutex);
1719                 printk(KERN_ERR "Error setting key for crypto context\n");
1720                 rc = -EINVAL;
1721                 goto out;
1722         }
1723         rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
1724                                       auth_tok->session_key.encrypted_key_size);
1725         mutex_unlock(tfm_mutex);
1726         if (unlikely(rc)) {
1727                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1728                 goto out;
1729         }
1730         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1731         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1732                auth_tok->session_key.decrypted_key_size);
1733         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1734         if (unlikely(ecryptfs_verbosity > 0)) {
1735                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1736                                 crypt_stat->key_size);
1737                 ecryptfs_dump_hex(crypt_stat->key,
1738                                   crypt_stat->key_size);
1739         }
1740 out:
1741         return rc;
1742 }
1743
1744 /**
1745  * ecryptfs_parse_packet_set
1746  * @crypt_stat: The cryptographic context
1747  * @src: Virtual address of region of memory containing the packets
1748  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1749  *
1750  * Get crypt_stat to have the file's session key if the requisite key
1751  * is available to decrypt the session key.
1752  *
1753  * Returns Zero if a valid authentication token was retrieved and
1754  * processed; negative value for file not encrypted or for error
1755  * conditions.
1756  */
1757 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1758                               unsigned char *src,
1759                               struct dentry *ecryptfs_dentry)
1760 {
1761         size_t i = 0;
1762         size_t found_auth_tok;
1763         size_t next_packet_is_auth_tok_packet;
1764         struct list_head auth_tok_list;
1765         struct ecryptfs_auth_tok *matching_auth_tok;
1766         struct ecryptfs_auth_tok *candidate_auth_tok;
1767         char *candidate_auth_tok_sig;
1768         size_t packet_size;
1769         struct ecryptfs_auth_tok *new_auth_tok;
1770         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1771         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1772         size_t tag_11_contents_size;
1773         size_t tag_11_packet_size;
1774         struct key *auth_tok_key = NULL;
1775         int rc = 0;
1776
1777         INIT_LIST_HEAD(&auth_tok_list);
1778         /* Parse the header to find as many packets as we can; these will be
1779          * added the our &auth_tok_list */
1780         next_packet_is_auth_tok_packet = 1;
1781         while (next_packet_is_auth_tok_packet) {
1782                 size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
1783
1784                 switch (src[i]) {
1785                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1786                         rc = parse_tag_3_packet(crypt_stat,
1787                                                 (unsigned char *)&src[i],
1788                                                 &auth_tok_list, &new_auth_tok,
1789                                                 &packet_size, max_packet_size);
1790                         if (rc) {
1791                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1792                                                 "tag 3 packet\n");
1793                                 rc = -EIO;
1794                                 goto out_wipe_list;
1795                         }
1796                         i += packet_size;
1797                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1798                                                  sig_tmp_space,
1799                                                  ECRYPTFS_SIG_SIZE,
1800                                                  &tag_11_contents_size,
1801                                                  &tag_11_packet_size,
1802                                                  max_packet_size);
1803                         if (rc) {
1804                                 ecryptfs_printk(KERN_ERR, "No valid "
1805                                                 "(ecryptfs-specific) literal "
1806                                                 "packet containing "
1807                                                 "authentication token "
1808                                                 "signature found after "
1809                                                 "tag 3 packet\n");
1810                                 rc = -EIO;
1811                                 goto out_wipe_list;
1812                         }
1813                         i += tag_11_packet_size;
1814                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1815                                 ecryptfs_printk(KERN_ERR, "Expected "
1816                                                 "signature of size [%d]; "
1817                                                 "read size [%zd]\n",
1818                                                 ECRYPTFS_SIG_SIZE,
1819                                                 tag_11_contents_size);
1820                                 rc = -EIO;
1821                                 goto out_wipe_list;
1822                         }
1823                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1824                                         sig_tmp_space, tag_11_contents_size);
1825                         new_auth_tok->token.password.signature[
1826                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1827                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1828                         break;
1829                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1830                         rc = parse_tag_1_packet(crypt_stat,
1831                                                 (unsigned char *)&src[i],
1832                                                 &auth_tok_list, &new_auth_tok,
1833                                                 &packet_size, max_packet_size);
1834                         if (rc) {
1835                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1836                                                 "tag 1 packet\n");
1837                                 rc = -EIO;
1838                                 goto out_wipe_list;
1839                         }
1840                         i += packet_size;
1841                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1842                         break;
1843                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1844                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1845                                         "(Tag 11 not allowed by itself)\n");
1846                         rc = -EIO;
1847                         goto out_wipe_list;
1848                 default:
1849                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1850                                         "of the file header; hex value of "
1851                                         "character is [0x%.2x]\n", i, src[i]);
1852                         next_packet_is_auth_tok_packet = 0;
1853                 }
1854         }
1855         if (list_empty(&auth_tok_list)) {
1856                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1857                        "eCryptfs file; this is not supported in this version "
1858                        "of the eCryptfs kernel module\n");
1859                 rc = -EINVAL;
1860                 goto out;
1861         }
1862         /* auth_tok_list contains the set of authentication tokens
1863          * parsed from the metadata. We need to find a matching
1864          * authentication token that has the secret component(s)
1865          * necessary to decrypt the EFEK in the auth_tok parsed from
1866          * the metadata. There may be several potential matches, but
1867          * just one will be sufficient to decrypt to get the FEK. */
1868 find_next_matching_auth_tok:
1869         found_auth_tok = 0;
1870         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1871                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1872                 if (unlikely(ecryptfs_verbosity > 0)) {
1873                         ecryptfs_printk(KERN_DEBUG,
1874                                         "Considering cadidate auth tok:\n");
1875                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1876                 }
1877                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1878                                                candidate_auth_tok);
1879                 if (rc) {
1880                         printk(KERN_ERR
1881                                "Unrecognized candidate auth tok type: [%d]\n",
1882                                candidate_auth_tok->token_type);
1883                         rc = -EINVAL;
1884                         goto out_wipe_list;
1885                 }
1886                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1887                                                &matching_auth_tok,
1888                                                crypt_stat->mount_crypt_stat,
1889                                                candidate_auth_tok_sig);
1890                 if (!rc) {
1891                         found_auth_tok = 1;
1892                         goto found_matching_auth_tok;
1893                 }
1894         }
1895         if (!found_auth_tok) {
1896                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1897                                 "authentication token\n");
1898                 rc = -EIO;
1899                 goto out_wipe_list;
1900         }
1901 found_matching_auth_tok:
1902         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1903                 memcpy(&(candidate_auth_tok->token.private_key),
1904                        &(matching_auth_tok->token.private_key),
1905                        sizeof(struct ecryptfs_private_key));
1906                 up_write(&(auth_tok_key->sem));
1907                 key_put(auth_tok_key);
1908                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1909                                                        crypt_stat);
1910         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1911                 memcpy(&(candidate_auth_tok->token.password),
1912                        &(matching_auth_tok->token.password),
1913                        sizeof(struct ecryptfs_password));
1914                 up_write(&(auth_tok_key->sem));
1915                 key_put(auth_tok_key);
1916                 rc = decrypt_passphrase_encrypted_session_key(
1917                         candidate_auth_tok, crypt_stat);
1918         } else {
1919                 up_write(&(auth_tok_key->sem));
1920                 key_put(auth_tok_key);
1921                 rc = -EINVAL;
1922         }
1923         if (rc) {
1924                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1925
1926                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1927                                 "session key for authentication token with sig "
1928                                 "[%.*s]; rc = [%d]. Removing auth tok "
1929                                 "candidate from the list and searching for "
1930                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1931                                 candidate_auth_tok_sig, rc);
1932                 list_for_each_entry_safe(auth_tok_list_item,
1933                                          auth_tok_list_item_tmp,
1934                                          &auth_tok_list, list) {
1935                         if (candidate_auth_tok
1936                             == &auth_tok_list_item->auth_tok) {
1937                                 list_del(&auth_tok_list_item->list);
1938                                 kmem_cache_free(
1939                                         ecryptfs_auth_tok_list_item_cache,
1940                                         auth_tok_list_item);
1941                                 goto find_next_matching_auth_tok;
1942                         }
1943                 }
1944                 BUG();
1945         }
1946         rc = ecryptfs_compute_root_iv(crypt_stat);
1947         if (rc) {
1948                 ecryptfs_printk(KERN_ERR, "Error computing "
1949                                 "the root IV\n");
1950                 goto out_wipe_list;
1951         }
1952         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1953         if (rc) {
1954                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1955                                 "context for cipher [%s]; rc = [%d]\n",
1956                                 crypt_stat->cipher, rc);
1957         }
1958 out_wipe_list:
1959         wipe_auth_tok_list(&auth_tok_list);
1960 out:
1961         return rc;
1962 }
1963
1964 static int
1965 pki_encrypt_session_key(struct key *auth_tok_key,
1966                         struct ecryptfs_auth_tok *auth_tok,
1967                         struct ecryptfs_crypt_stat *crypt_stat,
1968                         struct ecryptfs_key_record *key_rec)
1969 {
1970         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1971         char *payload = NULL;
1972         size_t payload_len = 0;
1973         struct ecryptfs_message *msg;
1974         int rc;
1975
1976         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1977                                  ecryptfs_code_for_cipher_string(
1978                                          crypt_stat->cipher,
1979                                          crypt_stat->key_size),
1980                                  crypt_stat, &payload, &payload_len);
1981         up_write(&(auth_tok_key->sem));
1982         key_put(auth_tok_key);
1983         if (rc) {
1984                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1985                 goto out;
1986         }
1987         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1988         if (rc) {
1989                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1990                                 "ecryptfsd: %d\n", rc);
1991                 goto out;
1992         }
1993         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1994         if (rc) {
1995                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1996                                 "from the user space daemon\n");
1997                 rc = -EIO;
1998                 goto out;
1999         }
2000         rc = parse_tag_67_packet(key_rec, msg);
2001         if (rc)
2002                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
2003         kfree(msg);
2004 out:
2005         kfree(payload);
2006         return rc;
2007 }
2008 /**
2009  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2010  * @dest: Buffer into which to write the packet
2011  * @remaining_bytes: Maximum number of bytes that can be writtn
2012  * @auth_tok_key: The authentication token key to unlock and put when done with
2013  *                @auth_tok
2014  * @auth_tok: The authentication token used for generating the tag 1 packet
2015  * @crypt_stat: The cryptographic context
2016  * @key_rec: The key record struct for the tag 1 packet
2017  * @packet_size: This function will write the number of bytes that end
2018  *               up constituting the packet; set to zero on error
2019  *
2020  * Returns zero on success; non-zero on error.
2021  */
2022 static int
2023 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2024                    struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2025                    struct ecryptfs_crypt_stat *crypt_stat,
2026                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2027 {
2028         size_t i;
2029         size_t encrypted_session_key_valid = 0;
2030         size_t packet_size_length;
2031         size_t max_packet_size;
2032         int rc = 0;
2033
2034         (*packet_size) = 0;
2035         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2036                           ECRYPTFS_SIG_SIZE);
2037         encrypted_session_key_valid = 0;
2038         for (i = 0; i < crypt_stat->key_size; i++)
2039                 encrypted_session_key_valid |=
2040                         auth_tok->session_key.encrypted_key[i];
2041         if (encrypted_session_key_valid) {
2042                 memcpy(key_rec->enc_key,
2043                        auth_tok->session_key.encrypted_key,
2044                        auth_tok->session_key.encrypted_key_size);
2045                 up_write(&(auth_tok_key->sem));
2046                 key_put(auth_tok_key);
2047                 goto encrypted_session_key_set;
2048         }
2049         if (auth_tok->session_key.encrypted_key_size == 0)
2050                 auth_tok->session_key.encrypted_key_size =
2051                         auth_tok->token.private_key.key_size;
2052         rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2053                                      key_rec);
2054         if (rc) {
2055                 printk(KERN_ERR "Failed to encrypt session key via a key "
2056                        "module; rc = [%d]\n", rc);
2057                 goto out;
2058         }
2059         if (ecryptfs_verbosity > 0) {
2060                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2061                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2062         }
2063 encrypted_session_key_set:
2064         /* This format is inspired by OpenPGP; see RFC 2440
2065          * packet tag 1 */
2066         max_packet_size = (1                         /* Tag 1 identifier */
2067                            + 3                       /* Max Tag 1 packet size */
2068                            + 1                       /* Version */
2069                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2070                            + 1                       /* Cipher identifier */
2071                            + key_rec->enc_key_size); /* Encrypted key size */
2072         if (max_packet_size > (*remaining_bytes)) {
2073                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2074                        "need up to [%td] bytes, but there are only [%td] "
2075                        "available\n", max_packet_size, (*remaining_bytes));
2076                 rc = -EINVAL;
2077                 goto out;
2078         }
2079         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2080         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2081                                           (max_packet_size - 4),
2082                                           &packet_size_length);
2083         if (rc) {
2084                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2085                                 "header; cannot generate packet length\n");
2086                 goto out;
2087         }
2088         (*packet_size) += packet_size_length;
2089         dest[(*packet_size)++] = 0x03; /* version 3 */
2090         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2091         (*packet_size) += ECRYPTFS_SIG_SIZE;
2092         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2093         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2094                key_rec->enc_key_size);
2095         (*packet_size) += key_rec->enc_key_size;
2096 out:
2097         if (rc)
2098                 (*packet_size) = 0;
2099         else
2100                 (*remaining_bytes) -= (*packet_size);
2101         return rc;
2102 }
2103
2104 /**
2105  * write_tag_11_packet
2106  * @dest: Target into which Tag 11 packet is to be written
2107  * @remaining_bytes: Maximum packet length
2108  * @contents: Byte array of contents to copy in
2109  * @contents_length: Number of bytes in contents
2110  * @packet_length: Length of the Tag 11 packet written; zero on error
2111  *
2112  * Returns zero on success; non-zero on error.
2113  */
2114 static int
2115 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2116                     size_t contents_length, size_t *packet_length)
2117 {
2118         size_t packet_size_length;
2119         size_t max_packet_size;
2120         int rc = 0;
2121
2122         (*packet_length) = 0;
2123         /* This format is inspired by OpenPGP; see RFC 2440
2124          * packet tag 11 */
2125         max_packet_size = (1                   /* Tag 11 identifier */
2126                            + 3                 /* Max Tag 11 packet size */
2127                            + 1                 /* Binary format specifier */
2128                            + 1                 /* Filename length */
2129                            + 8                 /* Filename ("_CONSOLE") */
2130                            + 4                 /* Modification date */
2131                            + contents_length); /* Literal data */
2132         if (max_packet_size > (*remaining_bytes)) {
2133                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2134                        "need up to [%td] bytes, but there are only [%td] "
2135                        "available\n", max_packet_size, (*remaining_bytes));
2136                 rc = -EINVAL;
2137                 goto out;
2138         }
2139         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2140         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2141                                           (max_packet_size - 4),
2142                                           &packet_size_length);
2143         if (rc) {
2144                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2145                        "generate packet length. rc = [%d]\n", rc);
2146                 goto out;
2147         }
2148         (*packet_length) += packet_size_length;
2149         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2150         dest[(*packet_length)++] = 8;
2151         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2152         (*packet_length) += 8;
2153         memset(&dest[(*packet_length)], 0x00, 4);
2154         (*packet_length) += 4;
2155         memcpy(&dest[(*packet_length)], contents, contents_length);
2156         (*packet_length) += contents_length;
2157  out:
2158         if (rc)
2159                 (*packet_length) = 0;
2160         else
2161                 (*remaining_bytes) -= (*packet_length);
2162         return rc;
2163 }
2164
2165 /**
2166  * write_tag_3_packet
2167  * @dest: Buffer into which to write the packet
2168  * @remaining_bytes: Maximum number of bytes that can be written
2169  * @auth_tok: Authentication token
2170  * @crypt_stat: The cryptographic context
2171  * @key_rec: encrypted key
2172  * @packet_size: This function will write the number of bytes that end
2173  *               up constituting the packet; set to zero on error
2174  *
2175  * Returns zero on success; non-zero on error.
2176  */
2177 static int
2178 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2179                    struct ecryptfs_auth_tok *auth_tok,
2180                    struct ecryptfs_crypt_stat *crypt_stat,
2181                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2182 {
2183         size_t i;
2184         size_t encrypted_session_key_valid = 0;
2185         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2186         struct scatterlist dst_sg[2];
2187         struct scatterlist src_sg[2];
2188         struct mutex *tfm_mutex = NULL;
2189         u8 cipher_code;
2190         size_t packet_size_length;
2191         size_t max_packet_size;
2192         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2193                 crypt_stat->mount_crypt_stat;
2194         struct blkcipher_desc desc = {
2195                 .tfm = NULL,
2196                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
2197         };
2198         int rc = 0;
2199
2200         (*packet_size) = 0;
2201         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2202                           ECRYPTFS_SIG_SIZE);
2203         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2204                                                         crypt_stat->cipher);
2205         if (unlikely(rc)) {
2206                 printk(KERN_ERR "Internal error whilst attempting to get "
2207                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2208                        crypt_stat->cipher, rc);
2209                 goto out;
2210         }
2211         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2212                 struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);
2213
2214                 printk(KERN_WARNING "No key size specified at mount; "
2215                        "defaulting to [%d]\n", alg->max_keysize);
2216                 mount_crypt_stat->global_default_cipher_key_size =
2217                         alg->max_keysize;
2218         }
2219         if (crypt_stat->key_size == 0)
2220                 crypt_stat->key_size =
2221                         mount_crypt_stat->global_default_cipher_key_size;
2222         if (auth_tok->session_key.encrypted_key_size == 0)
2223                 auth_tok->session_key.encrypted_key_size =
2224                         crypt_stat->key_size;
2225         if (crypt_stat->key_size == 24
2226             && strcmp("aes", crypt_stat->cipher) == 0) {
2227                 memset((crypt_stat->key + 24), 0, 8);
2228                 auth_tok->session_key.encrypted_key_size = 32;
2229         } else
2230                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2231         key_rec->enc_key_size =
2232                 auth_tok->session_key.encrypted_key_size;
2233         encrypted_session_key_valid = 0;
2234         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2235                 encrypted_session_key_valid |=
2236                         auth_tok->session_key.encrypted_key[i];
2237         if (encrypted_session_key_valid) {
2238                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2239                                 "using auth_tok->session_key.encrypted_key, "
2240                                 "where key_rec->enc_key_size = [%zd]\n",
2241                                 key_rec->enc_key_size);
2242                 memcpy(key_rec->enc_key,
2243                        auth_tok->session_key.encrypted_key,
2244                        key_rec->enc_key_size);
2245                 goto encrypted_session_key_set;
2246         }
2247         if (auth_tok->token.password.flags &
2248             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2249                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2250                                 "session key encryption key of size [%d]\n",
2251                                 auth_tok->token.password.
2252                                 session_key_encryption_key_bytes);
2253                 memcpy(session_key_encryption_key,
2254                        auth_tok->token.password.session_key_encryption_key,
2255                        crypt_stat->key_size);
2256                 ecryptfs_printk(KERN_DEBUG,
2257                                 "Cached session key encryption key:\n");
2258                 if (ecryptfs_verbosity > 0)
2259                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2260         }
2261         if (unlikely(ecryptfs_verbosity > 0)) {
2262                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2263                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2264         }
2265         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2266                                  src_sg, 2);
2267         if (rc < 1 || rc > 2) {
2268                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2269                                 "for crypt_stat session key; expected rc = 1; "
2270                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2271                                 rc, key_rec->enc_key_size);
2272                 rc = -ENOMEM;
2273                 goto out;
2274         }
2275         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2276                                  dst_sg, 2);
2277         if (rc < 1 || rc > 2) {
2278                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2279                                 "for crypt_stat encrypted session key; "
2280                                 "expected rc = 1; got rc = [%d]. "
2281                                 "key_rec->enc_key_size = [%zd]\n", rc,
2282                                 key_rec->enc_key_size);
2283                 rc = -ENOMEM;
2284                 goto out;
2285         }
2286         mutex_lock(tfm_mutex);
2287         rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
2288                                      crypt_stat->key_size);
2289         if (rc < 0) {
2290                 mutex_unlock(tfm_mutex);
2291                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2292                                 "context; rc = [%d]\n", rc);
2293                 goto out;
2294         }
2295         rc = 0;
2296         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2297                         crypt_stat->key_size);
2298         rc = crypto_blkcipher_encrypt(&desc, dst_sg, src_sg,
2299                                       (*key_rec).enc_key_size);
2300         mutex_unlock(tfm_mutex);
2301         if (rc) {
2302                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2303                 goto out;
2304         }
2305         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2306         if (ecryptfs_verbosity > 0) {
2307                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2308                                 key_rec->enc_key_size);
2309                 ecryptfs_dump_hex(key_rec->enc_key,
2310                                   key_rec->enc_key_size);
2311         }
2312 encrypted_session_key_set:
2313         /* This format is inspired by OpenPGP; see RFC 2440
2314          * packet tag 3 */
2315         max_packet_size = (1                         /* Tag 3 identifier */
2316                            + 3                       /* Max Tag 3 packet size */
2317                            + 1                       /* Version */
2318                            + 1                       /* Cipher code */
2319                            + 1                       /* S2K specifier */
2320                            + 1                       /* Hash identifier */
2321                            + ECRYPTFS_SALT_SIZE      /* Salt */
2322                            + 1                       /* Hash iterations */
2323                            + key_rec->enc_key_size); /* Encrypted key size */
2324         if (max_packet_size > (*remaining_bytes)) {
2325                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2326                        "there are only [%td] available\n", max_packet_size,
2327                        (*remaining_bytes));
2328                 rc = -EINVAL;
2329                 goto out;
2330         }
2331         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2332         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2333          * to get the number of octets in the actual Tag 3 packet */
2334         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2335                                           (max_packet_size - 4),
2336                                           &packet_size_length);
2337         if (rc) {
2338                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2339                        "generate packet length. rc = [%d]\n", rc);
2340                 goto out;
2341         }
2342         (*packet_size) += packet_size_length;
2343         dest[(*packet_size)++] = 0x04; /* version 4 */
2344         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2345          * specified with strings */
2346         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2347                                                       crypt_stat->key_size);
2348         if (cipher_code == 0) {
2349                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2350                                 "cipher [%s]\n", crypt_stat->cipher);
2351                 rc = -EINVAL;
2352                 goto out;
2353         }
2354         dest[(*packet_size)++] = cipher_code;
2355         dest[(*packet_size)++] = 0x03;  /* S2K */
2356         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2357         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2358                ECRYPTFS_SALT_SIZE);
2359         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2360         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2361         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2362                key_rec->enc_key_size);
2363         (*packet_size) += key_rec->enc_key_size;
2364 out:
2365         if (rc)
2366                 (*packet_size) = 0;
2367         else
2368                 (*remaining_bytes) -= (*packet_size);
2369         return rc;
2370 }
2371
2372 struct kmem_cache *ecryptfs_key_record_cache;
2373
2374 /**
2375  * ecryptfs_generate_key_packet_set
2376  * @dest_base: Virtual address from which to write the key record set
2377  * @crypt_stat: The cryptographic context from which the
2378  *              authentication tokens will be retrieved
2379  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2380  *                   for the global parameters
2381  * @len: The amount written
2382  * @max: The maximum amount of data allowed to be written
2383  *
2384  * Generates a key packet set and writes it to the virtual address
2385  * passed in.
2386  *
2387  * Returns zero on success; non-zero on error.
2388  */
2389 int
2390 ecryptfs_generate_key_packet_set(char *dest_base,
2391                                  struct ecryptfs_crypt_stat *crypt_stat,
2392                                  struct dentry *ecryptfs_dentry, size_t *len,
2393                                  size_t max)
2394 {
2395         struct ecryptfs_auth_tok *auth_tok;
2396         struct key *auth_tok_key = NULL;
2397         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2398                 &ecryptfs_superblock_to_private(
2399                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2400         size_t written;
2401         struct ecryptfs_key_record *key_rec;
2402         struct ecryptfs_key_sig *key_sig;
2403         int rc = 0;
2404
2405         (*len) = 0;
2406         mutex_lock(&crypt_stat->keysig_list_mutex);
2407         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2408         if (!key_rec) {
2409                 rc = -ENOMEM;
2410                 goto out;
2411         }
2412         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2413                             crypt_stat_list) {
2414                 memset(key_rec, 0, sizeof(*key_rec));
2415                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2416                                                            &auth_tok,
2417                                                            mount_crypt_stat,
2418                                                            key_sig->keysig);
2419                 if (rc) {
2420                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2421                                "sig = [%s]\n", key_sig->keysig);
2422                         rc = process_find_global_auth_tok_for_sig_err(rc);
2423                         goto out_free;
2424                 }
2425                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2426                         rc = write_tag_3_packet((dest_base + (*len)),
2427                                                 &max, auth_tok,
2428                                                 crypt_stat, key_rec,
2429                                                 &written);
2430                         up_write(&(auth_tok_key->sem));
2431                         key_put(auth_tok_key);
2432                         if (rc) {
2433                                 ecryptfs_printk(KERN_WARNING, "Error "
2434                                                 "writing tag 3 packet\n");
2435                                 goto out_free;
2436                         }
2437                         (*len) += written;
2438                         /* Write auth tok signature packet */
2439                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2440                                                  key_rec->sig,
2441                                                  ECRYPTFS_SIG_SIZE, &written);
2442                         if (rc) {
2443                                 ecryptfs_printk(KERN_ERR, "Error writing "
2444                                                 "auth tok signature packet\n");
2445                                 goto out_free;
2446                         }
2447                         (*len) += written;
2448                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2449                         rc = write_tag_1_packet(dest_base + (*len), &max,
2450                                                 auth_tok_key, auth_tok,
2451                                                 crypt_stat, key_rec, &written);
2452                         if (rc) {
2453                                 ecryptfs_printk(KERN_WARNING, "Error "
2454                                                 "writing tag 1 packet\n");
2455                                 goto out_free;
2456                         }
2457                         (*len) += written;
2458                 } else {
2459                         up_write(&(auth_tok_key->sem));
2460                         key_put(auth_tok_key);
2461                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2462                                         "authentication token type\n");
2463                         rc = -EINVAL;
2464                         goto out_free;
2465                 }
2466         }
2467         if (likely(max > 0)) {
2468                 dest_base[(*len)] = 0x00;
2469         } else {
2470                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2471                 rc = -EIO;
2472         }
2473 out_free:
2474         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2475 out:
2476         if (rc)
2477                 (*len) = 0;
2478         mutex_unlock(&crypt_stat->keysig_list_mutex);
2479         return rc;
2480 }
2481
2482 struct kmem_cache *ecryptfs_key_sig_cache;
2483
2484 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2485 {
2486         struct ecryptfs_key_sig *new_key_sig;
2487
2488         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2489         if (!new_key_sig) {
2490                 printk(KERN_ERR
2491                        "Error allocating from ecryptfs_key_sig_cache\n");
2492                 return -ENOMEM;
2493         }
2494         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2495         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2496         /* Caller must hold keysig_list_mutex */
2497         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2498
2499         return 0;
2500 }
2501
2502 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2503
2504 int
2505 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2506                              char *sig, u32 global_auth_tok_flags)
2507 {
2508         struct ecryptfs_global_auth_tok *new_auth_tok;
2509         int rc = 0;
2510
2511         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2512                                         GFP_KERNEL);
2513         if (!new_auth_tok) {
2514                 rc = -ENOMEM;
2515                 printk(KERN_ERR "Error allocating from "
2516                        "ecryptfs_global_auth_tok_cache\n");
2517                 goto out;
2518         }
2519         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2520         new_auth_tok->flags = global_auth_tok_flags;
2521         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2522         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2523         list_add(&new_auth_tok->mount_crypt_stat_list,
2524                  &mount_crypt_stat->global_auth_tok_list);
2525         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2526 out:
2527         return rc;
2528 }
2529