fs/ecryptfs/keystore.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  * In-kernel key management code.  Includes functions to parse and
   4  * write authentication token-related packets with the underlying
   5  * file.
   6  *
   7  * Copyright (C) 2004-2006 International Business Machines Corp.
   8  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
   9  *              Michael C. Thompson <mcthomps@us.ibm.com>
  10  *              Trevor S. Highland <trevor.highland@gmail.com>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  25  * 02111-1307, USA.
  26  */
  27
  28 #include <linux/string.h>
  29 #include <linux/syscalls.h>
  30 #include <linux/pagemap.h>
  31 #include <linux/key.h>
  32 #include <linux/random.h>
  33 #include <linux/crypto.h>
  34 #include <linux/scatterlist.h>
  35 #include <linux/slab.h>
  36 #include "ecryptfs_kernel.h"
  37
  38 /**
  39  * request_key returned an error instead of a valid key address;
  40  * determine the type of error, make appropriate log entries, and
  41  * return an error code.
  42  */
  43 static int process_request_key_err(long err_code)
  44 {
  45         int rc = 0;
  46
  47         switch (err_code) {
  48         case -ENOKEY:
  49                 ecryptfs_printk(KERN_WARNING, "No key\n");
  50                 rc = -ENOENT;
  51                 break;
  52         case -EKEYEXPIRED:
  53                 ecryptfs_printk(KERN_WARNING, "Key expired\n");
  54                 rc = -ETIME;
  55                 break;
  56         case -EKEYREVOKED:
  57                 ecryptfs_printk(KERN_WARNING, "Key revoked\n");
  58                 rc = -EINVAL;
  59                 break;
  60         default:
  61                 ecryptfs_printk(KERN_WARNING, "Unknown error code: "
  62                                 "[0x%.16lx]\n", err_code);
  63                 rc = -EINVAL;
  64         }
  65         return rc;
  66 }
  67
  68 static int process_find_global_auth_tok_for_sig_err(int err_code)
  69 {
  70         int rc = err_code;
  71
  72         switch (err_code) {
  73         case -ENOENT:
  74                 ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
  75                 break;
  76         case -EINVAL:
  77                 ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
  78                 break;
  79         default:
  80                 rc = process_request_key_err(err_code);
  81                 break;
  82         }
  83         return rc;
  84 }
  85
  86 /**
  87  * ecryptfs_parse_packet_length
  88  * @data: Pointer to memory containing length at offset
  89  * @size: This function writes the decoded size to this memory
  90  *        address; zero on error
  91  * @length_size: The number of bytes occupied by the encoded length
  92  *
  93  * Returns zero on success; non-zero on error
  94  */
  95 int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
  96                                  size_t *length_size)
  97 {
  98         int rc = 0;
  99
 100         (*length_size) = 0;
 101         (*size) = 0;
 102         if (data[0] < 192) {
 103                 /* One-byte length */
 104                 (*size) = (unsigned char)data[0];
 105                 (*length_size) = 1;
 106         } else if (data[0] < 224) {
 107                 /* Two-byte length */
 108                 (*size) = (((unsigned char)(data[0]) - 192) * 256);
 109                 (*size) += ((unsigned char)(data[1]) + 192);
 110                 (*length_size) = 2;
 111         } else if (data[0] == 255) {
 112                 /* Five-byte length; we're not supposed to see this */
 113                 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
 114                                 "supported\n");
 115                 rc = -EINVAL;
 116                 goto out;
 117         } else {
 118                 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
 119                 rc = -EINVAL;
 120                 goto out;
 121         }
 122 out:
 123         return rc;
 124 }
 125
 126 /**
 127  * ecryptfs_write_packet_length
 128  * @dest: The byte array target into which to write the length. Must
 129  *        have at least 5 bytes allocated.
 130  * @size: The length to write.
 131  * @packet_size_length: The number of bytes used to encode the packet
 132  *                      length is written to this address.
 133  *
 134  * Returns zero on success; non-zero on error.
 135  */
 136 int ecryptfs_write_packet_length(char *dest, size_t size,
 137                                  size_t *packet_size_length)
 138 {
 139         int rc = 0;
 140
 141         if (size < 192) {
 142                 dest[0] = size;
 143                 (*packet_size_length) = 1;
 144         } else if (size < 65536) {
 145                 dest[0] = (((size - 192) / 256) + 192);
 146                 dest[1] = ((size - 192) % 256);
 147                 (*packet_size_length) = 2;
 148         } else {
 149                 rc = -EINVAL;
 150                 ecryptfs_printk(KERN_WARNING,
 151                                 "Unsupported packet size: [%zd]\n", size);
 152         }
 153         return rc;
 154 }
 155
 156 static int
 157 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
 158                     char **packet, size_t *packet_len)
 159 {
 160         size_t i = 0;
 161         size_t data_len;
 162         size_t packet_size_len;
 163         char *message;
 164         int rc;
 165
 166         /*
 167          *              ***** TAG 64 Packet Format *****
 168          *    | Content Type                       | 1 byte       |
 169          *    | Key Identifier Size                | 1 or 2 bytes |
 170          *    | Key Identifier                     | arbitrary    |
 171          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 172          *    | Encrypted File Encryption Key      | arbitrary    |
 173          */
 174         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
 175                     + session_key->encrypted_key_size);
 176         *packet = kmalloc(data_len, GFP_KERNEL);
 177         message = *packet;
 178         if (!message) {
 179                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 180                 rc = -ENOMEM;
 181                 goto out;
 182         }
 183         message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
 184         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 185                                           &packet_size_len);
 186         if (rc) {
 187                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 188                                 "header; cannot generate packet length\n");
 189                 goto out;
 190         }
 191         i += packet_size_len;
 192         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 193         i += ECRYPTFS_SIG_SIZE_HEX;
 194         rc = ecryptfs_write_packet_length(&message[i],
 195                                           session_key->encrypted_key_size,
 196                                           &packet_size_len);
 197         if (rc) {
 198                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
 199                                 "header; cannot generate packet length\n");
 200                 goto out;
 201         }
 202         i += packet_size_len;
 203         memcpy(&message[i], session_key->encrypted_key,
 204                session_key->encrypted_key_size);
 205         i += session_key->encrypted_key_size;
 206         *packet_len = i;
 207 out:
 208         return rc;
 209 }
 210
 211 static int
 212 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
 213                     struct ecryptfs_message *msg)
 214 {
 215         size_t i = 0;
 216         char *data;
 217         size_t data_len;
 218         size_t m_size;
 219         size_t message_len;
 220         u16 checksum = 0;
 221         u16 expected_checksum = 0;
 222         int rc;
 223
 224         /*
 225          *              ***** TAG 65 Packet Format *****
 226          *         | Content Type             | 1 byte       |
 227          *         | Status Indicator         | 1 byte       |
 228          *         | File Encryption Key Size | 1 or 2 bytes |
 229          *         | File Encryption Key      | arbitrary    |
 230          */
 231         message_len = msg->data_len;
 232         data = msg->data;
 233         if (message_len < 4) {
 234                 rc = -EIO;
 235                 goto out;
 236         }
 237         if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
 238                 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
 239                 rc = -EIO;
 240                 goto out;
 241         }
 242         if (data[i++]) {
 243                 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
 244                                 "[%d]\n", data[i-1]);
 245                 rc = -EIO;
 246                 goto out;
 247         }
 248         rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
 249         if (rc) {
 250                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 251                                 "rc = [%d]\n", rc);
 252                 goto out;
 253         }
 254         i += data_len;
 255         if (message_len < (i + m_size)) {
 256                 ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
 257                                 "is shorter than expected\n");
 258                 rc = -EIO;
 259                 goto out;
 260         }
 261         if (m_size < 3) {
 262                 ecryptfs_printk(KERN_ERR,
 263                                 "The decrypted key is not long enough to "
 264                                 "include a cipher code and checksum\n");
 265                 rc = -EIO;
 266                 goto out;
 267         }
 268         *cipher_code = data[i++];
 269         /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
 270         session_key->decrypted_key_size = m_size - 3;
 271         if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
 272                 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
 273                                 "the maximum key size [%d]\n",
 274                                 session_key->decrypted_key_size,
 275                                 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 276                 rc = -EIO;
 277                 goto out;
 278         }
 279         memcpy(session_key->decrypted_key, &data[i],
 280                session_key->decrypted_key_size);
 281         i += session_key->decrypted_key_size;
 282         expected_checksum += (unsigned char)(data[i++]) << 8;
 283         expected_checksum += (unsigned char)(data[i++]);
 284         for (i = 0; i < session_key->decrypted_key_size; i++)
 285                 checksum += session_key->decrypted_key[i];
 286         if (expected_checksum != checksum) {
 287                 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
 288                                 "encryption  key; expected [%x]; calculated "
 289                                 "[%x]\n", expected_checksum, checksum);
 290                 rc = -EIO;
 291         }
 292 out:
 293         return rc;
 294 }
 295
 296
 297 static int
 298 write_tag_66_packet(char *signature, u8 cipher_code,
 299                     struct ecryptfs_crypt_stat *crypt_stat, char **packet,
 300                     size_t *packet_len)
 301 {
 302         size_t i = 0;
 303         size_t j;
 304         size_t data_len;
 305         size_t checksum = 0;
 306         size_t packet_size_len;
 307         char *message;
 308         int rc;
 309
 310         /*
 311          *              ***** TAG 66 Packet Format *****
 312          *         | Content Type             | 1 byte       |
 313          *         | Key Identifier Size      | 1 or 2 bytes |
 314          *         | Key Identifier           | arbitrary    |
 315          *         | File Encryption Key Size | 1 or 2 bytes |
 316          *         | File Encryption Key      | arbitrary    |
 317          */
 318         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
 319         *packet = kmalloc(data_len, GFP_KERNEL);
 320         message = *packet;
 321         if (!message) {
 322                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
 323                 rc = -ENOMEM;
 324                 goto out;
 325         }
 326         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
 327         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
 328                                           &packet_size_len);
 329         if (rc) {
 330                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 331                                 "header; cannot generate packet length\n");
 332                 goto out;
 333         }
 334         i += packet_size_len;
 335         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
 336         i += ECRYPTFS_SIG_SIZE_HEX;
 337         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
 338         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
 339                                           &packet_size_len);
 340         if (rc) {
 341                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
 342                                 "header; cannot generate packet length\n");
 343                 goto out;
 344         }
 345         i += packet_size_len;
 346         message[i++] = cipher_code;
 347         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
 348         i += crypt_stat->key_size;
 349         for (j = 0; j < crypt_stat->key_size; j++)
 350                 checksum += crypt_stat->key[j];
 351         message[i++] = (checksum / 256) % 256;
 352         message[i++] = (checksum % 256);
 353         *packet_len = i;
 354 out:
 355         return rc;
 356 }
 357
 358 static int
 359 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
 360                     struct ecryptfs_message *msg)
 361 {
 362         size_t i = 0;
 363         char *data;
 364         size_t data_len;
 365         size_t message_len;
 366         int rc;
 367
 368         /*
 369          *              ***** TAG 65 Packet Format *****
 370          *    | Content Type                       | 1 byte       |
 371          *    | Status Indicator                   | 1 byte       |
 372          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
 373          *    | Encrypted File Encryption Key      | arbitrary    |
 374          */
 375         message_len = msg->data_len;
 376         data = msg->data;
 377         /* verify that everything through the encrypted FEK size is present */
 378         if (message_len < 4) {
 379                 rc = -EIO;
 380                 printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
 381                        "message length is [%d]\n", __func__, message_len, 4);
 382                 goto out;
 383         }
 384         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
 385                 rc = -EIO;
 386                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
 387                        __func__);
 388                 goto out;
 389         }
 390         if (data[i++]) {
 391                 rc = -EIO;
 392                 printk(KERN_ERR "%s: Status indicator has non zero "
 393                        "value [%d]\n", __func__, data[i-1]);
 394
 395                 goto out;
 396         }
 397         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
 398                                           &data_len);
 399         if (rc) {
 400                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
 401                                 "rc = [%d]\n", rc);
 402                 goto out;
 403         }
 404         i += data_len;
 405         if (message_len < (i + key_rec->enc_key_size)) {
 406                 rc = -EIO;
 407                 printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
 408                        __func__, message_len, (i + key_rec->enc_key_size));
 409                 goto out;
 410         }
 411         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
 412                 rc = -EIO;
 413                 printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
 414                        "the maximum key size [%d]\n", __func__,
 415                        key_rec->enc_key_size,
 416                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
 417                 goto out;
 418         }
 419         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
 420 out:
 421         return rc;
 422 }
 423
 424 /**
 425  * ecryptfs_verify_version
 426  * @version: The version number to confirm
 427  *
 428  * Returns zero on good version; non-zero otherwise
 429  */
 430 static int ecryptfs_verify_version(u16 version)
 431 {
 432         int rc = 0;
 433         unsigned char major;
 434         unsigned char minor;
 435
 436         major = ((version >> 8) & 0xFF);
 437         minor = (version & 0xFF);
 438         if (major != ECRYPTFS_VERSION_MAJOR) {
 439                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
 440                                 "Expected [%d]; got [%d]\n",
 441                                 ECRYPTFS_VERSION_MAJOR, major);
 442                 rc = -EINVAL;
 443                 goto out;
 444         }
 445         if (minor != ECRYPTFS_VERSION_MINOR) {
 446                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
 447                                 "Expected [%d]; got [%d]\n",
 448                                 ECRYPTFS_VERSION_MINOR, minor);
 449                 rc = -EINVAL;
 450                 goto out;
 451         }
 452 out:
 453         return rc;
 454 }
 455
 456 /**
 457  * ecryptfs_verify_auth_tok_from_key
 458  * @auth_tok_key: key containing the authentication token
 459  * @auth_tok: authentication token
 460  *
 461  * Returns zero on valid auth tok; -EINVAL otherwise
 462  */
 463 static int
 464 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
 465                                   struct ecryptfs_auth_tok **auth_tok)
 466 {
 467         int rc = 0;
 468
 469         (*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
 470         if (ecryptfs_verify_version((*auth_tok)->version)) {
 471                 printk(KERN_ERR "Data structure version mismatch. Userspace "
 472                        "tools must match eCryptfs kernel module with major "
 473                        "version [%d] and minor version [%d]\n",
 474                        ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
 475                 rc = -EINVAL;
 476                 goto out;
 477         }
 478         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
 479             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
 480                 printk(KERN_ERR "Invalid auth_tok structure "
 481                        "returned from key query\n");
 482                 rc = -EINVAL;
 483                 goto out;
 484         }
 485 out:
 486         return rc;
 487 }
 488
 489 static int
 490 ecryptfs_find_global_auth_tok_for_sig(
 491         struct key **auth_tok_key,
 492         struct ecryptfs_auth_tok **auth_tok,
 493         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
 494 {
 495         struct ecryptfs_global_auth_tok *walker;
 496         int rc = 0;
 497
 498         (*auth_tok_key) = NULL;
 499         (*auth_tok) = NULL;
 500         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 501         list_for_each_entry(walker,
 502                             &mount_crypt_stat->global_auth_tok_list,
 503                             mount_crypt_stat_list) {
 504                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
 505                         continue;
 506
 507                 if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
 508                         rc = -EINVAL;
 509                         goto out;
 510                 }
 511
 512                 rc = key_validate(walker->global_auth_tok_key);
 513                 if (rc) {
 514                         if (rc == -EKEYEXPIRED)
 515                                 goto out;
 516                         goto out_invalid_auth_tok;
 517                 }
 518
 519                 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 = (1                   /* Tag 70 identifier */
 682                               + 3                 /* Max Tag 70 packet size */
 683                               + ECRYPTFS_SIG_SIZE /* FNEK sig */
 684                               + 1                 /* Cipher identifier */
 685                               + s->block_aligned_filename_size);
 686         if (dest == NULL) {
 687                 (*packet_size) = s->max_packet_size;
 688                 goto out_unlock;
 689         }
 690         if (s->max_packet_size > (*remaining_bytes)) {
 691                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
 692                        "[%zd] available\n", __func__, s->max_packet_size,
 693                        (*remaining_bytes));
 694                 rc = -EINVAL;
 695                 goto out_unlock;
 696         }
 697         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
 698                                             GFP_KERNEL);
 699         if (!s->block_aligned_filename) {
 700                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
 701                        "kzalloc [%zd] bytes\n", __func__,
 702                        s->block_aligned_filename_size);
 703                 rc = -ENOMEM;
 704                 goto out_unlock;
 705         }
 706         s->i = 0;
 707         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
 708         rc = ecryptfs_write_packet_length(&dest[s->i],
 709                                           (ECRYPTFS_SIG_SIZE
 710                                            + 1 /* Cipher code */
 711                                            + s->block_aligned_filename_size),
 712                                           &s->packet_size_len);
 713         if (rc) {
 714                 printk(KERN_ERR "%s: Error generating tag 70 packet "
 715                        "header; cannot generate packet length; rc = [%d]\n",
 716                        __func__, rc);
 717                 goto out_free_unlock;
 718         }
 719         s->i += s->packet_size_len;
 720         ecryptfs_from_hex(&dest[s->i],
 721                           mount_crypt_stat->global_default_fnek_sig,
 722                           ECRYPTFS_SIG_SIZE);
 723         s->i += ECRYPTFS_SIG_SIZE;
 724         s->cipher_code = ecryptfs_code_for_cipher_string(
 725                 mount_crypt_stat->global_default_fn_cipher_name,
 726                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 727         if (s->cipher_code == 0) {
 728                 printk(KERN_WARNING "%s: Unable to generate code for "
 729                        "cipher [%s] with key bytes [%zd]\n", __func__,
 730                        mount_crypt_stat->global_default_fn_cipher_name,
 731                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 732                 rc = -EINVAL;
 733                 goto out_free_unlock;
 734         }
 735         dest[s->i++] = s->cipher_code;
 736         /* TODO: Support other key modules than passphrase for
 737          * filename encryption */
 738         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
 739                 rc = -EOPNOTSUPP;
 740                 printk(KERN_INFO "%s: Filename encryption only supports "
 741                        "password tokens\n", __func__);
 742                 goto out_free_unlock;
 743         }
 744         sg_init_one(
 745                 &s->hash_sg,
 746                 (u8 *)s->auth_tok->token.password.session_key_encryption_key,
 747                 s->auth_tok->token.password.session_key_encryption_key_bytes);
 748         s->hash_desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 749         s->hash_desc.tfm = crypto_alloc_hash(ECRYPTFS_TAG_70_DIGEST, 0,
 750                                              CRYPTO_ALG_ASYNC);
 751         if (IS_ERR(s->hash_desc.tfm)) {
 752                         rc = PTR_ERR(s->hash_desc.tfm);
 753                         printk(KERN_ERR "%s: Error attempting to "
 754                                "allocate hash crypto context; rc = [%d]\n",
 755                                __func__, rc);
 756                         goto out_free_unlock;
 757         }
 758         rc = crypto_hash_init(&s->hash_desc);
 759         if (rc) {
 760                 printk(KERN_ERR
 761                        "%s: Error initializing crypto hash; rc = [%d]\n",
 762                        __func__, rc);
 763                 goto out_release_free_unlock;
 764         }
 765         rc = crypto_hash_update(
 766                 &s->hash_desc, &s->hash_sg,
 767                 s->auth_tok->token.password.session_key_encryption_key_bytes);
 768         if (rc) {
 769                 printk(KERN_ERR
 770                        "%s: Error updating crypto hash; rc = [%d]\n",
 771                        __func__, rc);
 772                 goto out_release_free_unlock;
 773         }
 774         rc = crypto_hash_final(&s->hash_desc, s->hash);
 775         if (rc) {
 776                 printk(KERN_ERR
 777                        "%s: Error finalizing crypto hash; rc = [%d]\n",
 778                        __func__, rc);
 779                 goto out_release_free_unlock;
 780         }
 781         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
 782                 s->block_aligned_filename[s->j] =
 783                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
 784                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
 785                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
 786                         sg_init_one(&s->hash_sg, (u8 *)s->hash,
 787                                     ECRYPTFS_TAG_70_DIGEST_SIZE);
 788                         rc = crypto_hash_init(&s->hash_desc);
 789                         if (rc) {
 790                                 printk(KERN_ERR
 791                                        "%s: Error initializing crypto hash; "
 792                                        "rc = [%d]\n", __func__, rc);
 793                                 goto out_release_free_unlock;
 794                         }
 795                         rc = crypto_hash_update(&s->hash_desc, &s->hash_sg,
 796                                                 ECRYPTFS_TAG_70_DIGEST_SIZE);
 797                         if (rc) {
 798                                 printk(KERN_ERR
 799                                        "%s: Error updating crypto hash; "
 800                                        "rc = [%d]\n", __func__, rc);
 801                                 goto out_release_free_unlock;
 802                         }
 803                         rc = crypto_hash_final(&s->hash_desc, s->tmp_hash);
 804                         if (rc) {
 805                                 printk(KERN_ERR
 806                                        "%s: Error finalizing crypto hash; "
 807                                        "rc = [%d]\n", __func__, rc);
 808                                 goto out_release_free_unlock;
 809                         }
 810                         memcpy(s->hash, s->tmp_hash,
 811                                ECRYPTFS_TAG_70_DIGEST_SIZE);
 812                 }
 813                 if (s->block_aligned_filename[s->j] == '\0')
 814                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
 815         }
 816         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
 817                filename_size);
 818         rc = virt_to_scatterlist(s->block_aligned_filename,
 819                                  s->block_aligned_filename_size, s->src_sg, 2);
 820         if (rc < 1) {
 821                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 822                        "convert filename memory to scatterlist; rc = [%d]. "
 823                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
 824                        s->block_aligned_filename_size);
 825                 goto out_release_free_unlock;
 826         }
 827         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
 828                                  s->dst_sg, 2);
 829         if (rc < 1) {
 830                 printk(KERN_ERR "%s: Internal error whilst attempting to "
 831                        "convert encrypted filename memory to scatterlist; "
 832                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
 833                        __func__, rc, s->block_aligned_filename_size);
 834                 goto out_release_free_unlock;
 835         }
 836         /* The characters in the first block effectively do the job
 837          * of the IV here, so we just use 0's for the IV. Note the
 838          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
 839          * >= ECRYPTFS_MAX_IV_BYTES. */
 840         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
 841         s->desc.info = s->iv;
 842         rc = crypto_blkcipher_setkey(
 843                 s->desc.tfm,
 844                 s->auth_tok->token.password.session_key_encryption_key,
 845                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
 846         if (rc < 0) {
 847                 printk(KERN_ERR "%s: Error setting key for crypto context; "
 848                        "rc = [%d]. s->auth_tok->token.password.session_key_"
 849                        "encryption_key = [0x%p]; mount_crypt_stat->"
 850                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
 851                        rc,
 852                        s->auth_tok->token.password.session_key_encryption_key,
 853                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
 854                 goto out_release_free_unlock;
 855         }
 856         rc = crypto_blkcipher_encrypt_iv(&s->desc, s->dst_sg, s->src_sg,
 857                                          s->block_aligned_filename_size);
 858         if (rc) {
 859                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
 860                        "rc = [%d]\n", __func__, rc);
 861                 goto out_release_free_unlock;
 862         }
 863         s->i += s->block_aligned_filename_size;
 864         (*packet_size) = s->i;
 865         (*remaining_bytes) -= (*packet_size);
 866 out_release_free_unlock:
 867         crypto_free_hash(s->hash_desc.tfm);
 868 out_free_unlock:
 869         kzfree(s->block_aligned_filename);
 870 out_unlock:
 871         mutex_unlock(s->tfm_mutex);
 872 out:
 873         if (auth_tok_key) {
 874                 up_write(&(auth_tok_key->sem));
 875                 key_put(auth_tok_key);
 876         }
 877         kfree(s);
 878         return rc;
 879 }
 880
 881 struct ecryptfs_parse_tag_70_packet_silly_stack {
 882         u8 cipher_code;
 883         size_t max_packet_size;
 884         size_t packet_size_len;
 885         size_t parsed_tag_70_packet_size;
 886         size_t block_aligned_filename_size;
 887         size_t block_size;
 888         size_t i;
 889         struct mutex *tfm_mutex;
 890         char *decrypted_filename;
 891         struct ecryptfs_auth_tok *auth_tok;
 892         struct scatterlist src_sg[2];
 893         struct scatterlist dst_sg[2];
 894         struct blkcipher_desc desc;
 895         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
 896         char iv[ECRYPTFS_MAX_IV_BYTES];
 897         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
 898 };
 899
 900 /**
 901  * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 902  * @filename: This function kmalloc's the memory for the filename
 903  * @filename_size: This function sets this to the amount of memory
 904  *                 kmalloc'd for the filename
 905  * @packet_size: This function sets this to the the number of octets
 906  *               in the packet parsed
 907  * @mount_crypt_stat: The mount-wide cryptographic context
 908  * @data: The memory location containing the start of the tag 70
 909  *        packet
 910  * @max_packet_size: The maximum legal size of the packet to be parsed
 911  *                   from @data
 912  *
 913  * Returns zero on success; non-zero otherwise
 914  */
 915 int
 916 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 917                              size_t *packet_size,
 918                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 919                              char *data, size_t max_packet_size)
 920 {
 921         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
 922         struct key *auth_tok_key = NULL;
 923         int rc = 0;
 924
 925         (*packet_size) = 0;
 926         (*filename_size) = 0;
 927         (*filename) = NULL;
 928         s = kmalloc(sizeof(*s), GFP_KERNEL);
 929         if (!s) {
 930                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 931                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
 932                 rc = -ENOMEM;
 933                 goto out;
 934         }
 935         s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 936         if (max_packet_size < (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1)) {
 937                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
 938                        "at least [%d]\n", __func__, max_packet_size,
 939                         (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1));
 940                 rc = -EINVAL;
 941                 goto out;
 942         }
 943         /* Octet 0: Tag 70 identifier
 944          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
 945          *              and block-aligned encrypted filename size)
 946          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
 947          * Octet N2-N3: Cipher identifier (1 octet)
 948          * Octets N3-N4: Block-aligned encrypted filename
 949          *  - Consists of a minimum number of random numbers, a \0
 950          *    separator, and then the filename */
 951         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
 952                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
 953                        "tag [0x%.2x]\n", __func__,
 954                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
 955                 rc = -EINVAL;
 956                 goto out;
 957         }
 958         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
 959                                           &s->parsed_tag_70_packet_size,
 960                                           &s->packet_size_len);
 961         if (rc) {
 962                 printk(KERN_WARNING "%s: Error parsing packet length; "
 963                        "rc = [%d]\n", __func__, rc);
 964                 goto out;
 965         }
 966         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
 967                                           - ECRYPTFS_SIG_SIZE - 1);
 968         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
 969             > max_packet_size) {
 970                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
 971                        "size is [%zd]\n", __func__, max_packet_size,
 972                        (1 + s->packet_size_len + 1
 973                         + s->block_aligned_filename_size));
 974                 rc = -EINVAL;
 975                 goto out;
 976         }
 977         (*packet_size) += s->packet_size_len;
 978         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
 979                         ECRYPTFS_SIG_SIZE);
 980         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
 981         (*packet_size) += ECRYPTFS_SIG_SIZE;
 982         s->cipher_code = data[(*packet_size)++];
 983         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
 984         if (rc) {
 985                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
 986                        __func__, s->cipher_code);
 987                 goto out;
 988         }
 989         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
 990                                             &s->auth_tok, mount_crypt_stat,
 991                                             s->fnek_sig_hex);
 992         if (rc) {
 993                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
 994                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
 995                        rc);
 996                 goto out;
 997         }
 998         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->desc.tfm,
 999                                                         &s->tfm_mutex,
1000                                                         s->cipher_string);
1001         if (unlikely(rc)) {
1002                 printk(KERN_ERR "Internal error whilst attempting to get "
1003                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1004                        s->cipher_string, rc);
1005                 goto out;
1006         }
1007         mutex_lock(s->tfm_mutex);
1008         rc = virt_to_scatterlist(&data[(*packet_size)],
1009                                  s->block_aligned_filename_size, s->src_sg, 2);
1010         if (rc < 1) {
1011                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1012                        "convert encrypted filename memory to scatterlist; "
1013                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1014                        __func__, rc, s->block_aligned_filename_size);
1015                 goto out_unlock;
1016         }
1017         (*packet_size) += s->block_aligned_filename_size;
1018         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
1019                                         GFP_KERNEL);
1020         if (!s->decrypted_filename) {
1021                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1022                        "kmalloc [%zd] bytes\n", __func__,
1023                        s->block_aligned_filename_size);
1024                 rc = -ENOMEM;
1025                 goto out_unlock;
1026         }
1027         rc = virt_to_scatterlist(s->decrypted_filename,
1028                                  s->block_aligned_filename_size, s->dst_sg, 2);
1029         if (rc < 1) {
1030                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1031                        "convert decrypted filename memory to scatterlist; "
1032                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1033                        __func__, rc, s->block_aligned_filename_size);
1034                 goto out_free_unlock;
1035         }
1036         /* The characters in the first block effectively do the job of
1037          * the IV here, so we just use 0's for the IV. Note the
1038          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1039          * >= ECRYPTFS_MAX_IV_BYTES. */
1040         memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
1041         s->desc.info = s->iv;
1042         /* TODO: Support other key modules than passphrase for
1043          * filename encryption */
1044         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1045                 rc = -EOPNOTSUPP;
1046                 printk(KERN_INFO "%s: Filename encryption only supports "
1047                        "password tokens\n", __func__);
1048                 goto out_free_unlock;
1049         }
1050         rc = crypto_blkcipher_setkey(
1051                 s->desc.tfm,
1052                 s->auth_tok->token.password.session_key_encryption_key,
1053                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1054         if (rc < 0) {
1055                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1056                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1057                        "encryption_key = [0x%p]; mount_crypt_stat->"
1058                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1059                        rc,
1060                        s->auth_tok->token.password.session_key_encryption_key,
1061                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1062                 goto out_free_unlock;
1063         }
1064         rc = crypto_blkcipher_decrypt_iv(&s->desc, s->dst_sg, s->src_sg,
1065                                          s->block_aligned_filename_size);
1066         if (rc) {
1067                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1068                        "rc = [%d]\n", __func__, rc);
1069                 goto out_free_unlock;
1070         }
1071         s->i = 0;
1072         while (s->decrypted_filename[s->i] != '\0'
1073                && s->i < s->block_aligned_filename_size)
1074                 s->i++;
1075         if (s->i == s->block_aligned_filename_size) {
1076                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1077                        "find valid separator between random characters and "
1078                        "the filename\n", __func__);
1079                 rc = -EINVAL;
1080                 goto out_free_unlock;
1081         }
1082         s->i++;
1083         (*filename_size) = (s->block_aligned_filename_size - s->i);
1084         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1085                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1086                        "invalid\n", __func__, (*filename_size));
1087                 rc = -EINVAL;
1088                 goto out_free_unlock;
1089         }
1090         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1091         if (!(*filename)) {
1092                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1093                        "kmalloc [%zd] bytes\n", __func__,
1094                        ((*filename_size) + 1));
1095                 rc = -ENOMEM;
1096                 goto out_free_unlock;
1097         }
1098         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1099         (*filename)[(*filename_size)] = '\0';
1100 out_free_unlock:
1101         kfree(s->decrypted_filename);
1102 out_unlock:
1103         mutex_unlock(s->tfm_mutex);
1104 out:
1105         if (rc) {
1106                 (*packet_size) = 0;
1107                 (*filename_size) = 0;
1108                 (*filename) = NULL;
1109         }
1110         if (auth_tok_key) {
1111                 up_write(&(auth_tok_key->sem));
1112                 key_put(auth_tok_key);
1113         }
1114         kfree(s);
1115         return rc;
1116 }
1117
1118 static int
1119 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1120 {
1121         int rc = 0;
1122
1123         (*sig) = NULL;
1124         switch (auth_tok->token_type) {
1125         case ECRYPTFS_PASSWORD:
1126                 (*sig) = auth_tok->token.password.signature;
1127                 break;
1128         case ECRYPTFS_PRIVATE_KEY:
1129                 (*sig) = auth_tok->token.private_key.signature;
1130                 break;
1131         default:
1132                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1133                        auth_tok->token_type);
1134                 rc = -EINVAL;
1135         }
1136         return rc;
1137 }
1138
1139 /**
1140  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1141  * @auth_tok: The key authentication token used to decrypt the session key
1142  * @crypt_stat: The cryptographic context
1143  *
1144  * Returns zero on success; non-zero error otherwise.
1145  */
1146 static int
1147 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1148                                   struct ecryptfs_crypt_stat *crypt_stat)
1149 {
1150         u8 cipher_code = 0;
1151         struct ecryptfs_msg_ctx *msg_ctx;
1152         struct ecryptfs_message *msg = NULL;
1153         char *auth_tok_sig;
1154         char *payload = NULL;
1155         size_t payload_len;
1156         int rc;
1157
1158         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1159         if (rc) {
1160                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1161                        auth_tok->token_type);
1162                 goto out;
1163         }
1164         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1165                                  &payload, &payload_len);
1166         if (rc) {
1167                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1168                 goto out;
1169         }
1170         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1171         if (rc) {
1172                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1173                                 "ecryptfsd\n");
1174                 goto out;
1175         }
1176         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1177         if (rc) {
1178                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1179                                 "from the user space daemon\n");
1180                 rc = -EIO;
1181                 goto out;
1182         }
1183         rc = parse_tag_65_packet(&(auth_tok->session_key),
1184                                  &cipher_code, msg);
1185         if (rc) {
1186                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1187                        rc);
1188                 goto out;
1189         }
1190         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1191         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1192                auth_tok->session_key.decrypted_key_size);
1193         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1194         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1195         if (rc) {
1196                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1197                                 cipher_code)
1198                 goto out;
1199         }
1200         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1201         if (ecryptfs_verbosity > 0) {
1202                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1203                 ecryptfs_dump_hex(crypt_stat->key,
1204                                   crypt_stat->key_size);
1205         }
1206 out:
1207         if (msg)
1208                 kfree(msg);
1209         kfree(payload);
1210         return rc;
1211 }
1212
1213 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1214 {
1215         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1216         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1217
1218         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1219                                  auth_tok_list_head, list) {
1220                 list_del(&auth_tok_list_item->list);
1221                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1222                                 auth_tok_list_item);
1223         }
1224 }
1225
1226 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1227
1228 /**
1229  * parse_tag_1_packet
1230  * @crypt_stat: The cryptographic context to modify based on packet contents
1231  * @data: The raw bytes of the packet.
1232  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1233  *                 a new authentication token will be placed at the
1234  *                 end of this list for this packet.
1235  * @new_auth_tok: Pointer to a pointer to memory that this function
1236  *                allocates; sets the memory address of the pointer to
1237  *                NULL on error. This object is added to the
1238  *                auth_tok_list.
1239  * @packet_size: This function writes the size of the parsed packet
1240  *               into this memory location; zero on error.
1241  * @max_packet_size: The maximum allowable packet size
1242  *
1243  * Returns zero on success; non-zero on error.
1244  */
1245 static int
1246 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1247                    unsigned char *data, struct list_head *auth_tok_list,
1248                    struct ecryptfs_auth_tok **new_auth_tok,
1249                    size_t *packet_size, size_t max_packet_size)
1250 {
1251         size_t body_size;
1252         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1253         size_t length_size;
1254         int rc = 0;
1255
1256         (*packet_size) = 0;
1257         (*new_auth_tok) = NULL;
1258         /**
1259          * This format is inspired by OpenPGP; see RFC 2440
1260          * packet tag 1
1261          *
1262          * Tag 1 identifier (1 byte)
1263          * Max Tag 1 packet size (max 3 bytes)
1264          * Version (1 byte)
1265          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1266          * Cipher identifier (1 byte)
1267          * Encrypted key size (arbitrary)
1268          *
1269          * 12 bytes minimum packet size
1270          */
1271         if (unlikely(max_packet_size < 12)) {
1272                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1273                 rc = -EINVAL;
1274                 goto out;
1275         }
1276         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1277                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1278                        ECRYPTFS_TAG_1_PACKET_TYPE);
1279                 rc = -EINVAL;
1280                 goto out;
1281         }
1282         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1283          * at end of function upon failure */
1284         auth_tok_list_item =
1285                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1286                                   GFP_KERNEL);
1287         if (!auth_tok_list_item) {
1288                 printk(KERN_ERR "Unable to allocate memory\n");
1289                 rc = -ENOMEM;
1290                 goto out;
1291         }
1292         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1293         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1294                                           &length_size);
1295         if (rc) {
1296                 printk(KERN_WARNING "Error parsing packet length; "
1297                        "rc = [%d]\n", rc);
1298                 goto out_free;
1299         }
1300         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1301                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1302                 rc = -EINVAL;
1303                 goto out_free;
1304         }
1305         (*packet_size) += length_size;
1306         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1307                 printk(KERN_WARNING "Packet size exceeds max\n");
1308                 rc = -EINVAL;
1309                 goto out_free;
1310         }
1311         if (unlikely(data[(*packet_size)++] != 0x03)) {
1312                 printk(KERN_WARNING "Unknown version number [%d]\n",
1313                        data[(*packet_size) - 1]);
1314                 rc = -EINVAL;
1315                 goto out_free;
1316         }
1317         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1318                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1319         *packet_size += ECRYPTFS_SIG_SIZE;
1320         /* This byte is skipped because the kernel does not need to
1321          * know which public key encryption algorithm was used */
1322         (*packet_size)++;
1323         (*new_auth_tok)->session_key.encrypted_key_size =
1324                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1325         if ((*new_auth_tok)->session_key.encrypted_key_size
1326             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1327                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1328                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
1329                 rc = -EINVAL;
1330                 goto out;
1331         }
1332         memcpy((*new_auth_tok)->session_key.encrypted_key,
1333                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1334         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1335         (*new_auth_tok)->session_key.flags &=
1336                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1337         (*new_auth_tok)->session_key.flags |=
1338                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1339         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1340         (*new_auth_tok)->flags = 0;
1341         (*new_auth_tok)->session_key.flags &=
1342                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1343         (*new_auth_tok)->session_key.flags &=
1344                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1345         list_add(&auth_tok_list_item->list, auth_tok_list);
1346         goto out;
1347 out_free:
1348         (*new_auth_tok) = NULL;
1349         memset(auth_tok_list_item, 0,
1350                sizeof(struct ecryptfs_auth_tok_list_item));
1351         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1352                         auth_tok_list_item);
1353 out:
1354         if (rc)
1355                 (*packet_size) = 0;
1356         return rc;
1357 }
1358
1359 /**
1360  * parse_tag_3_packet
1361  * @crypt_stat: The cryptographic context to modify based on packet
1362  *              contents.
1363  * @data: The raw bytes of the packet.
1364  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1365  *                 a new authentication token will be placed at the end
1366  *                 of this list for this packet.
1367  * @new_auth_tok: Pointer to a pointer to memory that this function
1368  *                allocates; sets the memory address of the pointer to
1369  *                NULL on error. This object is added to the
1370  *                auth_tok_list.
1371  * @packet_size: This function writes the size of the parsed packet
1372  *               into this memory location; zero on error.
1373  * @max_packet_size: maximum number of bytes to parse
1374  *
1375  * Returns zero on success; non-zero on error.
1376  */
1377 static int
1378 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1379                    unsigned char *data, struct list_head *auth_tok_list,
1380                    struct ecryptfs_auth_tok **new_auth_tok,
1381                    size_t *packet_size, size_t max_packet_size)
1382 {
1383         size_t body_size;
1384         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1385         size_t length_size;
1386         int rc = 0;
1387
1388         (*packet_size) = 0;
1389         (*new_auth_tok) = NULL;
1390         /**
1391          *This format is inspired by OpenPGP; see RFC 2440
1392          * packet tag 3
1393          *
1394          * Tag 3 identifier (1 byte)
1395          * Max Tag 3 packet size (max 3 bytes)
1396          * Version (1 byte)
1397          * Cipher code (1 byte)
1398          * S2K specifier (1 byte)
1399          * Hash identifier (1 byte)
1400          * Salt (ECRYPTFS_SALT_SIZE)
1401          * Hash iterations (1 byte)
1402          * Encrypted key (arbitrary)
1403          *
1404          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1405          */
1406         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1407                 printk(KERN_ERR "Max packet size too large\n");
1408                 rc = -EINVAL;
1409                 goto out;
1410         }
1411         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1412                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1413                        ECRYPTFS_TAG_3_PACKET_TYPE);
1414                 rc = -EINVAL;
1415                 goto out;
1416         }
1417         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1418          * at end of function upon failure */
1419         auth_tok_list_item =
1420             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1421         if (!auth_tok_list_item) {
1422                 printk(KERN_ERR "Unable to allocate memory\n");
1423                 rc = -ENOMEM;
1424                 goto out;
1425         }
1426         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1427         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1428                                           &length_size);
1429         if (rc) {
1430                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1431                        rc);
1432                 goto out_free;
1433         }
1434         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1435                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1436                 rc = -EINVAL;
1437                 goto out_free;
1438         }
1439         (*packet_size) += length_size;
1440         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1441                 printk(KERN_ERR "Packet size exceeds max\n");
1442                 rc = -EINVAL;
1443                 goto out_free;
1444         }
1445         (*new_auth_tok)->session_key.encrypted_key_size =
1446                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1447         if ((*new_auth_tok)->session_key.encrypted_key_size
1448             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1449                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1450                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1451                 rc = -EINVAL;
1452                 goto out_free;
1453         }
1454         if (unlikely(data[(*packet_size)++] != 0x04)) {
1455                 printk(KERN_WARNING "Unknown version number [%d]\n",
1456                        data[(*packet_size) - 1]);
1457                 rc = -EINVAL;
1458                 goto out_free;
1459         }
1460         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1461                                             (u16)data[(*packet_size)]);
1462         if (rc)
1463                 goto out_free;
1464         /* A little extra work to differentiate among the AES key
1465          * sizes; see RFC2440 */
1466         switch(data[(*packet_size)++]) {
1467         case RFC2440_CIPHER_AES_192:
1468                 crypt_stat->key_size = 24;
1469                 break;
1470         default:
1471                 crypt_stat->key_size =
1472                         (*new_auth_tok)->session_key.encrypted_key_size;
1473         }
1474         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1475         if (rc)
1476                 goto out_free;
1477         if (unlikely(data[(*packet_size)++] != 0x03)) {
1478                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1479                 rc = -ENOSYS;
1480                 goto out_free;
1481         }
1482         /* TODO: finish the hash mapping */
1483         switch (data[(*packet_size)++]) {
1484         case 0x01: /* See RFC2440 for these numbers and their mappings */
1485                 /* Choose MD5 */
1486                 memcpy((*new_auth_tok)->token.password.salt,
1487                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1488                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1489                 /* This conversion was taken straight from RFC2440 */
1490                 (*new_auth_tok)->token.password.hash_iterations =
1491                         ((u32) 16 + (data[(*packet_size)] & 15))
1492                                 << ((data[(*packet_size)] >> 4) + 6);
1493                 (*packet_size)++;
1494                 /* Friendly reminder:
1495                  * (*new_auth_tok)->session_key.encrypted_key_size =
1496                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1497                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1498                        &data[(*packet_size)],
1499                        (*new_auth_tok)->session_key.encrypted_key_size);
1500                 (*packet_size) +=
1501                         (*new_auth_tok)->session_key.encrypted_key_size;
1502                 (*new_auth_tok)->session_key.flags &=
1503                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1504                 (*new_auth_tok)->session_key.flags |=
1505                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1506                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1507                 break;
1508         default:
1509                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1510                                 "[%d]\n", data[(*packet_size) - 1]);
1511                 rc = -ENOSYS;
1512                 goto out_free;
1513         }
1514         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1515         /* TODO: Parametarize; we might actually want userspace to
1516          * decrypt the session key. */
1517         (*new_auth_tok)->session_key.flags &=
1518                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1519         (*new_auth_tok)->session_key.flags &=
1520                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1521         list_add(&auth_tok_list_item->list, auth_tok_list);
1522         goto out;
1523 out_free:
1524         (*new_auth_tok) = NULL;
1525         memset(auth_tok_list_item, 0,
1526                sizeof(struct ecryptfs_auth_tok_list_item));
1527         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1528                         auth_tok_list_item);
1529 out:
1530         if (rc)
1531                 (*packet_size) = 0;
1532         return rc;
1533 }
1534
1535 /**
1536  * parse_tag_11_packet
1537  * @data: The raw bytes of the packet
1538  * @contents: This function writes the data contents of the literal
1539  *            packet into this memory location
1540  * @max_contents_bytes: The maximum number of bytes that this function
1541  *                      is allowed to write into contents
1542  * @tag_11_contents_size: This function writes the size of the parsed
1543  *                        contents into this memory location; zero on
1544  *                        error
1545  * @packet_size: This function writes the size of the parsed packet
1546  *               into this memory location; zero on error
1547  * @max_packet_size: maximum number of bytes to parse
1548  *
1549  * Returns zero on success; non-zero on error.
1550  */
1551 static int
1552 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1553                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1554                     size_t *packet_size, size_t max_packet_size)
1555 {
1556         size_t body_size;
1557         size_t length_size;
1558         int rc = 0;
1559
1560         (*packet_size) = 0;
1561         (*tag_11_contents_size) = 0;
1562         /* This format is inspired by OpenPGP; see RFC 2440
1563          * packet tag 11
1564          *
1565          * Tag 11 identifier (1 byte)
1566          * Max Tag 11 packet size (max 3 bytes)
1567          * Binary format specifier (1 byte)
1568          * Filename length (1 byte)
1569          * Filename ("_CONSOLE") (8 bytes)
1570          * Modification date (4 bytes)
1571          * Literal data (arbitrary)
1572          *
1573          * We need at least 16 bytes of data for the packet to even be
1574          * valid.
1575          */
1576         if (max_packet_size < 16) {
1577                 printk(KERN_ERR "Maximum packet size too small\n");
1578                 rc = -EINVAL;
1579                 goto out;
1580         }
1581         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1582                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1583                 rc = -EINVAL;
1584                 goto out;
1585         }
1586         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1587                                           &length_size);
1588         if (rc) {
1589                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1590                 goto out;
1591         }
1592         if (body_size < 14) {
1593                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1594                 rc = -EINVAL;
1595                 goto out;
1596         }
1597         (*packet_size) += length_size;
1598         (*tag_11_contents_size) = (body_size - 14);
1599         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1600                 printk(KERN_ERR "Packet size exceeds max\n");
1601                 rc = -EINVAL;
1602                 goto out;
1603         }
1604         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1605                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1606                        "expected size\n");
1607                 rc = -EINVAL;
1608                 goto out;
1609         }
1610         if (data[(*packet_size)++] != 0x62) {
1611                 printk(KERN_WARNING "Unrecognizable packet\n");
1612                 rc = -EINVAL;
1613                 goto out;
1614         }
1615         if (data[(*packet_size)++] != 0x08) {
1616                 printk(KERN_WARNING "Unrecognizable packet\n");
1617                 rc = -EINVAL;
1618                 goto out;
1619         }
1620         (*packet_size) += 12; /* Ignore filename and modification date */
1621         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1622         (*packet_size) += (*tag_11_contents_size);
1623 out:
1624         if (rc) {
1625                 (*packet_size) = 0;
1626                 (*tag_11_contents_size) = 0;
1627         }
1628         return rc;
1629 }
1630
1631 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1632                                       struct ecryptfs_auth_tok **auth_tok,
1633                                       char *sig)
1634 {
1635         int rc = 0;
1636
1637         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1638         if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1639                 (*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1640                 if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1641                         printk(KERN_ERR "Could not find key with description: [%s]\n",
1642                               sig);
1643                         rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1644                         (*auth_tok_key) = NULL;
1645                         goto out;
1646                 }
1647         }
1648         down_write(&(*auth_tok_key)->sem);
1649         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1650         if (rc) {
1651                 up_write(&(*auth_tok_key)->sem);
1652                 key_put(*auth_tok_key);
1653                 (*auth_tok_key) = NULL;
1654                 goto out;
1655         }
1656 out:
1657         return rc;
1658 }
1659
1660 /**
1661  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1662  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1663  * @crypt_stat: The cryptographic context
1664  *
1665  * Returns zero on success; non-zero error otherwise
1666  */
1667 static int
1668 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1669                                          struct ecryptfs_crypt_stat *crypt_stat)
1670 {
1671         struct scatterlist dst_sg[2];
1672         struct scatterlist src_sg[2];
1673         struct mutex *tfm_mutex;
1674         struct blkcipher_desc desc = {
1675                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
1676         };
1677         int rc = 0;
1678
1679         if (unlikely(ecryptfs_verbosity > 0)) {
1680                 ecryptfs_printk(
1681                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1682                         auth_tok->token.password.session_key_encryption_key_bytes);
1683                 ecryptfs_dump_hex(
1684                         auth_tok->token.password.session_key_encryption_key,
1685                         auth_tok->token.password.session_key_encryption_key_bytes);
1686         }
1687         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
1688                                                         crypt_stat->cipher);
1689         if (unlikely(rc)) {
1690                 printk(KERN_ERR "Internal error whilst attempting to get "
1691                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1692                        crypt_stat->cipher, rc);
1693                 goto out;
1694         }
1695         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1696                                  auth_tok->session_key.encrypted_key_size,
1697                                  src_sg, 2);
1698         if (rc < 1 || rc > 2) {
1699                 printk(KERN_ERR "Internal error whilst attempting to convert "
1700                         "auth_tok->session_key.encrypted_key to scatterlist; "
1701                         "expected rc = 1; got rc = [%d]. "
1702                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1703                         auth_tok->session_key.encrypted_key_size);
1704                 goto out;
1705         }
1706         auth_tok->session_key.decrypted_key_size =
1707                 auth_tok->session_key.encrypted_key_size;
1708         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1709                                  auth_tok->session_key.decrypted_key_size,
1710                                  dst_sg, 2);
1711         if (rc < 1 || rc > 2) {
1712                 printk(KERN_ERR "Internal error whilst attempting to convert "
1713                         "auth_tok->session_key.decrypted_key to scatterlist; "
1714                         "expected rc = 1; got rc = [%d]\n", rc);
1715                 goto out;
1716         }
1717         mutex_lock(tfm_mutex);
1718         rc = crypto_blkcipher_setkey(
1719                 desc.tfm, auth_tok->token.password.session_key_encryption_key,
1720                 crypt_stat->key_size);
1721         if (unlikely(rc < 0)) {
1722                 mutex_unlock(tfm_mutex);
1723                 printk(KERN_ERR "Error setting key for crypto context\n");
1724                 rc = -EINVAL;
1725                 goto out;
1726         }
1727         rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
1728                                       auth_tok->session_key.encrypted_key_size);
1729         mutex_unlock(tfm_mutex);
1730         if (unlikely(rc)) {
1731                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1732                 goto out;
1733         }
1734         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1735         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1736                auth_tok->session_key.decrypted_key_size);
1737         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1738         if (unlikely(ecryptfs_verbosity > 0)) {
1739                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1740                                 crypt_stat->key_size);
1741                 ecryptfs_dump_hex(crypt_stat->key,
1742                                   crypt_stat->key_size);
1743         }
1744 out:
1745         return rc;
1746 }
1747
1748 /**
1749  * ecryptfs_parse_packet_set
1750  * @crypt_stat: The cryptographic context
1751  * @src: Virtual address of region of memory containing the packets
1752  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1753  *
1754  * Get crypt_stat to have the file's session key if the requisite key
1755  * is available to decrypt the session key.
1756  *
1757  * Returns Zero if a valid authentication token was retrieved and
1758  * processed; negative value for file not encrypted or for error
1759  * conditions.
1760  */
1761 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1762                               unsigned char *src,
1763                               struct dentry *ecryptfs_dentry)
1764 {
1765         size_t i = 0;
1766         size_t found_auth_tok;
1767         size_t next_packet_is_auth_tok_packet;
1768         struct list_head auth_tok_list;
1769         struct ecryptfs_auth_tok *matching_auth_tok;
1770         struct ecryptfs_auth_tok *candidate_auth_tok;
1771         char *candidate_auth_tok_sig;
1772         size_t packet_size;
1773         struct ecryptfs_auth_tok *new_auth_tok;
1774         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1775         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1776         size_t tag_11_contents_size;
1777         size_t tag_11_packet_size;
1778         struct key *auth_tok_key = NULL;
1779         int rc = 0;
1780
1781         INIT_LIST_HEAD(&auth_tok_list);
1782         /* Parse the header to find as many packets as we can; these will be
1783          * added the our &auth_tok_list */
1784         next_packet_is_auth_tok_packet = 1;
1785         while (next_packet_is_auth_tok_packet) {
1786                 size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
1787
1788                 switch (src[i]) {
1789                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1790                         rc = parse_tag_3_packet(crypt_stat,
1791                                                 (unsigned char *)&src[i],
1792                                                 &auth_tok_list, &new_auth_tok,
1793                                                 &packet_size, max_packet_size);
1794                         if (rc) {
1795                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1796                                                 "tag 3 packet\n");
1797                                 rc = -EIO;
1798                                 goto out_wipe_list;
1799                         }
1800                         i += packet_size;
1801                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1802                                                  sig_tmp_space,
1803                                                  ECRYPTFS_SIG_SIZE,
1804                                                  &tag_11_contents_size,
1805                                                  &tag_11_packet_size,
1806                                                  max_packet_size);
1807                         if (rc) {
1808                                 ecryptfs_printk(KERN_ERR, "No valid "
1809                                                 "(ecryptfs-specific) literal "
1810                                                 "packet containing "
1811                                                 "authentication token "
1812                                                 "signature found after "
1813                                                 "tag 3 packet\n");
1814                                 rc = -EIO;
1815                                 goto out_wipe_list;
1816                         }
1817                         i += tag_11_packet_size;
1818                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1819                                 ecryptfs_printk(KERN_ERR, "Expected "
1820                                                 "signature of size [%d]; "
1821                                                 "read size [%zd]\n",
1822                                                 ECRYPTFS_SIG_SIZE,
1823                                                 tag_11_contents_size);
1824                                 rc = -EIO;
1825                                 goto out_wipe_list;
1826                         }
1827                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1828                                         sig_tmp_space, tag_11_contents_size);
1829                         new_auth_tok->token.password.signature[
1830                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1831                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1832                         break;
1833                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1834                         rc = parse_tag_1_packet(crypt_stat,
1835                                                 (unsigned char *)&src[i],
1836                                                 &auth_tok_list, &new_auth_tok,
1837                                                 &packet_size, max_packet_size);
1838                         if (rc) {
1839                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1840                                                 "tag 1 packet\n");
1841                                 rc = -EIO;
1842                                 goto out_wipe_list;
1843                         }
1844                         i += packet_size;
1845                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1846                         break;
1847                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1848                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1849                                         "(Tag 11 not allowed by itself)\n");
1850                         rc = -EIO;
1851                         goto out_wipe_list;
1852                         break;
1853                 default:
1854                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1855                                         "of the file header; hex value of "
1856                                         "character is [0x%.2x]\n", i, src[i]);
1857                         next_packet_is_auth_tok_packet = 0;
1858                 }
1859         }
1860         if (list_empty(&auth_tok_list)) {
1861                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1862                        "eCryptfs file; this is not supported in this version "
1863                        "of the eCryptfs kernel module\n");
1864                 rc = -EINVAL;
1865                 goto out;
1866         }
1867         /* auth_tok_list contains the set of authentication tokens
1868          * parsed from the metadata. We need to find a matching
1869          * authentication token that has the secret component(s)
1870          * necessary to decrypt the EFEK in the auth_tok parsed from
1871          * the metadata. There may be several potential matches, but
1872          * just one will be sufficient to decrypt to get the FEK. */
1873 find_next_matching_auth_tok:
1874         found_auth_tok = 0;
1875         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1876                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1877                 if (unlikely(ecryptfs_verbosity > 0)) {
1878                         ecryptfs_printk(KERN_DEBUG,
1879                                         "Considering cadidate auth tok:\n");
1880                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1881                 }
1882                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1883                                                candidate_auth_tok);
1884                 if (rc) {
1885                         printk(KERN_ERR
1886                                "Unrecognized candidate auth tok type: [%d]\n",
1887                                candidate_auth_tok->token_type);
1888                         rc = -EINVAL;
1889                         goto out_wipe_list;
1890                 }
1891                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1892                                                &matching_auth_tok,
1893                                                crypt_stat->mount_crypt_stat,
1894                                                candidate_auth_tok_sig);
1895                 if (!rc) {
1896                         found_auth_tok = 1;
1897                         goto found_matching_auth_tok;
1898                 }
1899         }
1900         if (!found_auth_tok) {
1901                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1902                                 "authentication token\n");
1903                 rc = -EIO;
1904                 goto out_wipe_list;
1905         }
1906 found_matching_auth_tok:
1907         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1908                 memcpy(&(candidate_auth_tok->token.private_key),
1909                        &(matching_auth_tok->token.private_key),
1910                        sizeof(struct ecryptfs_private_key));
1911                 up_write(&(auth_tok_key->sem));
1912                 key_put(auth_tok_key);
1913                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1914                                                        crypt_stat);
1915         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1916                 memcpy(&(candidate_auth_tok->token.password),
1917                        &(matching_auth_tok->token.password),
1918                        sizeof(struct ecryptfs_password));
1919                 up_write(&(auth_tok_key->sem));
1920                 key_put(auth_tok_key);
1921                 rc = decrypt_passphrase_encrypted_session_key(
1922                         candidate_auth_tok, crypt_stat);
1923         } else {
1924                 up_write(&(auth_tok_key->sem));
1925                 key_put(auth_tok_key);
1926                 rc = -EINVAL;
1927         }
1928         if (rc) {
1929                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1930
1931                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1932                                 "session key for authentication token with sig "
1933                                 "[%.*s]; rc = [%d]. Removing auth tok "
1934                                 "candidate from the list and searching for "
1935                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1936                                 candidate_auth_tok_sig, rc);
1937                 list_for_each_entry_safe(auth_tok_list_item,
1938                                          auth_tok_list_item_tmp,
1939                                          &auth_tok_list, list) {
1940                         if (candidate_auth_tok
1941                             == &auth_tok_list_item->auth_tok) {
1942                                 list_del(&auth_tok_list_item->list);
1943                                 kmem_cache_free(
1944                                         ecryptfs_auth_tok_list_item_cache,
1945                                         auth_tok_list_item);
1946                                 goto find_next_matching_auth_tok;
1947                         }
1948                 }
1949                 BUG();
1950         }
1951         rc = ecryptfs_compute_root_iv(crypt_stat);
1952         if (rc) {
1953                 ecryptfs_printk(KERN_ERR, "Error computing "
1954                                 "the root IV\n");
1955                 goto out_wipe_list;
1956         }
1957         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1958         if (rc) {
1959                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1960                                 "context for cipher [%s]; rc = [%d]\n",
1961                                 crypt_stat->cipher, rc);
1962         }
1963 out_wipe_list:
1964         wipe_auth_tok_list(&auth_tok_list);
1965 out:
1966         return rc;
1967 }
1968
1969 static int
1970 pki_encrypt_session_key(struct key *auth_tok_key,
1971                         struct ecryptfs_auth_tok *auth_tok,
1972                         struct ecryptfs_crypt_stat *crypt_stat,
1973                         struct ecryptfs_key_record *key_rec)
1974 {
1975         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1976         char *payload = NULL;
1977         size_t payload_len = 0;
1978         struct ecryptfs_message *msg;
1979         int rc;
1980
1981         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1982                                  ecryptfs_code_for_cipher_string(
1983                                          crypt_stat->cipher,
1984                                          crypt_stat->key_size),
1985                                  crypt_stat, &payload, &payload_len);
1986         up_write(&(auth_tok_key->sem));
1987         key_put(auth_tok_key);
1988         if (rc) {
1989                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1990                 goto out;
1991         }
1992         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1993         if (rc) {
1994                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1995                                 "ecryptfsd\n");
1996                 goto out;
1997         }
1998         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1999         if (rc) {
2000                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
2001                                 "from the user space daemon\n");
2002                 rc = -EIO;
2003                 goto out;
2004         }
2005         rc = parse_tag_67_packet(key_rec, msg);
2006         if (rc)
2007                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
2008         kfree(msg);
2009 out:
2010         kfree(payload);
2011         return rc;
2012 }
2013 /**
2014  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2015  * @dest: Buffer into which to write the packet
2016  * @remaining_bytes: Maximum number of bytes that can be writtn
2017  * @auth_tok_key: The authentication token key to unlock and put when done with
2018  *                @auth_tok
2019  * @auth_tok: The authentication token used for generating the tag 1 packet
2020  * @crypt_stat: The cryptographic context
2021  * @key_rec: The key record struct for the tag 1 packet
2022  * @packet_size: This function will write the number of bytes that end
2023  *               up constituting the packet; set to zero on error
2024  *
2025  * Returns zero on success; non-zero on error.
2026  */
2027 static int
2028 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2029                    struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2030                    struct ecryptfs_crypt_stat *crypt_stat,
2031                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2032 {
2033         size_t i;
2034         size_t encrypted_session_key_valid = 0;
2035         size_t packet_size_length;
2036         size_t max_packet_size;
2037         int rc = 0;
2038
2039         (*packet_size) = 0;
2040         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2041                           ECRYPTFS_SIG_SIZE);
2042         encrypted_session_key_valid = 0;
2043         for (i = 0; i < crypt_stat->key_size; i++)
2044                 encrypted_session_key_valid |=
2045                         auth_tok->session_key.encrypted_key[i];
2046         if (encrypted_session_key_valid) {
2047                 memcpy(key_rec->enc_key,
2048                        auth_tok->session_key.encrypted_key,
2049                        auth_tok->session_key.encrypted_key_size);
2050                 up_write(&(auth_tok_key->sem));
2051                 key_put(auth_tok_key);
2052                 goto encrypted_session_key_set;
2053         }
2054         if (auth_tok->session_key.encrypted_key_size == 0)
2055                 auth_tok->session_key.encrypted_key_size =
2056                         auth_tok->token.private_key.key_size;
2057         rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2058                                      key_rec);
2059         if (rc) {
2060                 printk(KERN_ERR "Failed to encrypt session key via a key "
2061                        "module; rc = [%d]\n", rc);
2062                 goto out;
2063         }
2064         if (ecryptfs_verbosity > 0) {
2065                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2066                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2067         }
2068 encrypted_session_key_set:
2069         /* This format is inspired by OpenPGP; see RFC 2440
2070          * packet tag 1 */
2071         max_packet_size = (1                         /* Tag 1 identifier */
2072                            + 3                       /* Max Tag 1 packet size */
2073                            + 1                       /* Version */
2074                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2075                            + 1                       /* Cipher identifier */
2076                            + key_rec->enc_key_size); /* Encrypted key size */
2077         if (max_packet_size > (*remaining_bytes)) {
2078                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2079                        "need up to [%td] bytes, but there are only [%td] "
2080                        "available\n", max_packet_size, (*remaining_bytes));
2081                 rc = -EINVAL;
2082                 goto out;
2083         }
2084         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2085         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2086                                           (max_packet_size - 4),
2087                                           &packet_size_length);
2088         if (rc) {
2089                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2090                                 "header; cannot generate packet length\n");
2091                 goto out;
2092         }
2093         (*packet_size) += packet_size_length;
2094         dest[(*packet_size)++] = 0x03; /* version 3 */
2095         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2096         (*packet_size) += ECRYPTFS_SIG_SIZE;
2097         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2098         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2099                key_rec->enc_key_size);
2100         (*packet_size) += key_rec->enc_key_size;
2101 out:
2102         if (rc)
2103                 (*packet_size) = 0;
2104         else
2105                 (*remaining_bytes) -= (*packet_size);
2106         return rc;
2107 }
2108
2109 /**
2110  * write_tag_11_packet
2111  * @dest: Target into which Tag 11 packet is to be written
2112  * @remaining_bytes: Maximum packet length
2113  * @contents: Byte array of contents to copy in
2114  * @contents_length: Number of bytes in contents
2115  * @packet_length: Length of the Tag 11 packet written; zero on error
2116  *
2117  * Returns zero on success; non-zero on error.
2118  */
2119 static int
2120 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2121                     size_t contents_length, size_t *packet_length)
2122 {
2123         size_t packet_size_length;
2124         size_t max_packet_size;
2125         int rc = 0;
2126
2127         (*packet_length) = 0;
2128         /* This format is inspired by OpenPGP; see RFC 2440
2129          * packet tag 11 */
2130         max_packet_size = (1                   /* Tag 11 identifier */
2131                            + 3                 /* Max Tag 11 packet size */
2132                            + 1                 /* Binary format specifier */
2133                            + 1                 /* Filename length */
2134                            + 8                 /* Filename ("_CONSOLE") */
2135                            + 4                 /* Modification date */
2136                            + contents_length); /* Literal data */
2137         if (max_packet_size > (*remaining_bytes)) {
2138                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2139                        "need up to [%td] bytes, but there are only [%td] "
2140                        "available\n", max_packet_size, (*remaining_bytes));
2141                 rc = -EINVAL;
2142                 goto out;
2143         }
2144         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2145         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2146                                           (max_packet_size - 4),
2147                                           &packet_size_length);
2148         if (rc) {
2149                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2150                        "generate packet length. rc = [%d]\n", rc);
2151                 goto out;
2152         }
2153         (*packet_length) += packet_size_length;
2154         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2155         dest[(*packet_length)++] = 8;
2156         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2157         (*packet_length) += 8;
2158         memset(&dest[(*packet_length)], 0x00, 4);
2159         (*packet_length) += 4;
2160         memcpy(&dest[(*packet_length)], contents, contents_length);
2161         (*packet_length) += contents_length;
2162  out:
2163         if (rc)
2164                 (*packet_length) = 0;
2165         else
2166                 (*remaining_bytes) -= (*packet_length);
2167         return rc;
2168 }
2169
2170 /**
2171  * write_tag_3_packet
2172  * @dest: Buffer into which to write the packet
2173  * @remaining_bytes: Maximum number of bytes that can be written
2174  * @auth_tok: Authentication token
2175  * @crypt_stat: The cryptographic context
2176  * @key_rec: encrypted key
2177  * @packet_size: This function will write the number of bytes that end
2178  *               up constituting the packet; set to zero on error
2179  *
2180  * Returns zero on success; non-zero on error.
2181  */
2182 static int
2183 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2184                    struct ecryptfs_auth_tok *auth_tok,
2185                    struct ecryptfs_crypt_stat *crypt_stat,
2186                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2187 {
2188         size_t i;
2189         size_t encrypted_session_key_valid = 0;
2190         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2191         struct scatterlist dst_sg[2];
2192         struct scatterlist src_sg[2];
2193         struct mutex *tfm_mutex = NULL;
2194         u8 cipher_code;
2195         size_t packet_size_length;
2196         size_t max_packet_size;
2197         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2198                 crypt_stat->mount_crypt_stat;
2199         struct blkcipher_desc desc = {
2200                 .tfm = NULL,
2201                 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
2202         };
2203         int rc = 0;
2204
2205         (*packet_size) = 0;
2206         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2207                           ECRYPTFS_SIG_SIZE);
2208         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
2209                                                         crypt_stat->cipher);
2210         if (unlikely(rc)) {
2211                 printk(KERN_ERR "Internal error whilst attempting to get "
2212                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2213                        crypt_stat->cipher, rc);
2214                 goto out;
2215         }
2216         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2217                 struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);
2218
2219                 printk(KERN_WARNING "No key size specified at mount; "
2220                        "defaulting to [%d]\n", alg->max_keysize);
2221                 mount_crypt_stat->global_default_cipher_key_size =
2222                         alg->max_keysize;
2223         }
2224         if (crypt_stat->key_size == 0)
2225                 crypt_stat->key_size =
2226                         mount_crypt_stat->global_default_cipher_key_size;
2227         if (auth_tok->session_key.encrypted_key_size == 0)
2228                 auth_tok->session_key.encrypted_key_size =
2229                         crypt_stat->key_size;
2230         if (crypt_stat->key_size == 24
2231             && strcmp("aes", crypt_stat->cipher) == 0) {
2232                 memset((crypt_stat->key + 24), 0, 8);
2233                 auth_tok->session_key.encrypted_key_size = 32;
2234         } else
2235                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2236         key_rec->enc_key_size =
2237                 auth_tok->session_key.encrypted_key_size;
2238         encrypted_session_key_valid = 0;
2239         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2240                 encrypted_session_key_valid |=
2241                         auth_tok->session_key.encrypted_key[i];
2242         if (encrypted_session_key_valid) {
2243                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2244                                 "using auth_tok->session_key.encrypted_key, "
2245                                 "where key_rec->enc_key_size = [%zd]\n",
2246                                 key_rec->enc_key_size);
2247                 memcpy(key_rec->enc_key,
2248                        auth_tok->session_key.encrypted_key,
2249                        key_rec->enc_key_size);
2250                 goto encrypted_session_key_set;
2251         }
2252         if (auth_tok->token.password.flags &
2253             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2254                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2255                                 "session key encryption key of size [%d]\n",
2256                                 auth_tok->token.password.
2257                                 session_key_encryption_key_bytes);
2258                 memcpy(session_key_encryption_key,
2259                        auth_tok->token.password.session_key_encryption_key,
2260                        crypt_stat->key_size);
2261                 ecryptfs_printk(KERN_DEBUG,
2262                                 "Cached session key encryption key:\n");
2263                 if (ecryptfs_verbosity > 0)
2264                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2265         }
2266         if (unlikely(ecryptfs_verbosity > 0)) {
2267                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2268                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2269         }
2270         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2271                                  src_sg, 2);
2272         if (rc < 1 || rc > 2) {
2273                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2274                                 "for crypt_stat session key; expected rc = 1; "
2275                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2276                                 rc, key_rec->enc_key_size);
2277                 rc = -ENOMEM;
2278                 goto out;
2279         }
2280         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2281                                  dst_sg, 2);
2282         if (rc < 1 || rc > 2) {
2283                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2284                                 "for crypt_stat encrypted session key; "
2285                                 "expected rc = 1; got rc = [%d]. "
2286                                 "key_rec->enc_key_size = [%zd]\n", rc,
2287                                 key_rec->enc_key_size);
2288                 rc = -ENOMEM;
2289                 goto out;
2290         }
2291         mutex_lock(tfm_mutex);
2292         rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
2293                                      crypt_stat->key_size);
2294         if (rc < 0) {
2295                 mutex_unlock(tfm_mutex);
2296                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2297                                 "context; rc = [%d]\n", rc);
2298                 goto out;
2299         }
2300         rc = 0;
2301         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2302                         crypt_stat->key_size);
2303         rc = crypto_blkcipher_encrypt(&desc, dst_sg, src_sg,
2304                                       (*key_rec).enc_key_size);
2305         mutex_unlock(tfm_mutex);
2306         if (rc) {
2307                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2308                 goto out;
2309         }
2310         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2311         if (ecryptfs_verbosity > 0) {
2312                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2313                                 key_rec->enc_key_size);
2314                 ecryptfs_dump_hex(key_rec->enc_key,
2315                                   key_rec->enc_key_size);
2316         }
2317 encrypted_session_key_set:
2318         /* This format is inspired by OpenPGP; see RFC 2440
2319          * packet tag 3 */
2320         max_packet_size = (1                         /* Tag 3 identifier */
2321                            + 3                       /* Max Tag 3 packet size */
2322                            + 1                       /* Version */
2323                            + 1                       /* Cipher code */
2324                            + 1                       /* S2K specifier */
2325                            + 1                       /* Hash identifier */
2326                            + ECRYPTFS_SALT_SIZE      /* Salt */
2327                            + 1                       /* Hash iterations */
2328                            + key_rec->enc_key_size); /* Encrypted key size */
2329         if (max_packet_size > (*remaining_bytes)) {
2330                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2331                        "there are only [%td] available\n", max_packet_size,
2332                        (*remaining_bytes));
2333                 rc = -EINVAL;
2334                 goto out;
2335         }
2336         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2337         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2338          * to get the number of octets in the actual Tag 3 packet */
2339         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2340                                           (max_packet_size - 4),
2341                                           &packet_size_length);
2342         if (rc) {
2343                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2344                        "generate packet length. rc = [%d]\n", rc);
2345                 goto out;
2346         }
2347         (*packet_size) += packet_size_length;
2348         dest[(*packet_size)++] = 0x04; /* version 4 */
2349         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2350          * specified with strings */
2351         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2352                                                       crypt_stat->key_size);
2353         if (cipher_code == 0) {
2354                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2355                                 "cipher [%s]\n", crypt_stat->cipher);
2356                 rc = -EINVAL;
2357                 goto out;
2358         }
2359         dest[(*packet_size)++] = cipher_code;
2360         dest[(*packet_size)++] = 0x03;  /* S2K */
2361         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2362         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2363                ECRYPTFS_SALT_SIZE);
2364         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2365         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2366         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2367                key_rec->enc_key_size);
2368         (*packet_size) += key_rec->enc_key_size;
2369 out:
2370         if (rc)
2371                 (*packet_size) = 0;
2372         else
2373                 (*remaining_bytes) -= (*packet_size);
2374         return rc;
2375 }
2376
2377 struct kmem_cache *ecryptfs_key_record_cache;
2378
2379 /**
2380  * ecryptfs_generate_key_packet_set
2381  * @dest_base: Virtual address from which to write the key record set
2382  * @crypt_stat: The cryptographic context from which the
2383  *              authentication tokens will be retrieved
2384  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2385  *                   for the global parameters
2386  * @len: The amount written
2387  * @max: The maximum amount of data allowed to be written
2388  *
2389  * Generates a key packet set and writes it to the virtual address
2390  * passed in.
2391  *
2392  * Returns zero on success; non-zero on error.
2393  */
2394 int
2395 ecryptfs_generate_key_packet_set(char *dest_base,
2396                                  struct ecryptfs_crypt_stat *crypt_stat,
2397                                  struct dentry *ecryptfs_dentry, size_t *len,
2398                                  size_t max)
2399 {
2400         struct ecryptfs_auth_tok *auth_tok;
2401         struct key *auth_tok_key = NULL;
2402         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2403                 &ecryptfs_superblock_to_private(
2404                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2405         size_t written;
2406         struct ecryptfs_key_record *key_rec;
2407         struct ecryptfs_key_sig *key_sig;
2408         int rc = 0;
2409
2410         (*len) = 0;
2411         mutex_lock(&crypt_stat->keysig_list_mutex);
2412         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2413         if (!key_rec) {
2414                 rc = -ENOMEM;
2415                 goto out;
2416         }
2417         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2418                             crypt_stat_list) {
2419                 memset(key_rec, 0, sizeof(*key_rec));
2420                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2421                                                            &auth_tok,
2422                                                            mount_crypt_stat,
2423                                                            key_sig->keysig);
2424                 if (rc) {
2425                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2426                                "sig = [%s]\n", key_sig->keysig);
2427                         rc = process_find_global_auth_tok_for_sig_err(rc);
2428                         goto out_free;
2429                 }
2430                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2431                         rc = write_tag_3_packet((dest_base + (*len)),
2432                                                 &max, auth_tok,
2433                                                 crypt_stat, key_rec,
2434                                                 &written);
2435                         up_write(&(auth_tok_key->sem));
2436                         key_put(auth_tok_key);
2437                         if (rc) {
2438                                 ecryptfs_printk(KERN_WARNING, "Error "
2439                                                 "writing tag 3 packet\n");
2440                                 goto out_free;
2441                         }
2442                         (*len) += written;
2443                         /* Write auth tok signature packet */
2444                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2445                                                  key_rec->sig,
2446                                                  ECRYPTFS_SIG_SIZE, &written);
2447                         if (rc) {
2448                                 ecryptfs_printk(KERN_ERR, "Error writing "
2449                                                 "auth tok signature packet\n");
2450                                 goto out_free;
2451                         }
2452                         (*len) += written;
2453                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2454                         rc = write_tag_1_packet(dest_base + (*len), &max,
2455                                                 auth_tok_key, auth_tok,
2456                                                 crypt_stat, key_rec, &written);
2457                         if (rc) {
2458                                 ecryptfs_printk(KERN_WARNING, "Error "
2459                                                 "writing tag 1 packet\n");
2460                                 goto out_free;
2461                         }
2462                         (*len) += written;
2463                 } else {
2464                         up_write(&(auth_tok_key->sem));
2465                         key_put(auth_tok_key);
2466                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2467                                         "authentication token type\n");
2468                         rc = -EINVAL;
2469                         goto out_free;
2470                 }
2471         }
2472         if (likely(max > 0)) {
2473                 dest_base[(*len)] = 0x00;
2474         } else {
2475                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2476                 rc = -EIO;
2477         }
2478 out_free:
2479         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2480 out:
2481         if (rc)
2482                 (*len) = 0;
2483         mutex_unlock(&crypt_stat->keysig_list_mutex);
2484         return rc;
2485 }
2486
2487 struct kmem_cache *ecryptfs_key_sig_cache;
2488
2489 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2490 {
2491         struct ecryptfs_key_sig *new_key_sig;
2492
2493         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2494         if (!new_key_sig) {
2495                 printk(KERN_ERR
2496                        "Error allocating from ecryptfs_key_sig_cache\n");
2497                 return -ENOMEM;
2498         }
2499         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2500         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2501         /* Caller must hold keysig_list_mutex */
2502         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2503
2504         return 0;
2505 }
2506
2507 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2508
2509 int
2510 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2511                              char *sig, u32 global_auth_tok_flags)
2512 {
2513         struct ecryptfs_global_auth_tok *new_auth_tok;
2514         int rc = 0;
2515
2516         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2517                                         GFP_KERNEL);
2518         if (!new_auth_tok) {
2519                 rc = -ENOMEM;
2520                 printk(KERN_ERR "Error allocating from "
2521                        "ecryptfs_global_auth_tok_cache\n");
2522                 goto out;
2523         }
2524         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2525         new_auth_tok->flags = global_auth_tok_flags;
2526         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2527         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2528         list_add(&new_auth_tok->mount_crypt_stat_list,
2529                  &mount_crypt_stat->global_auth_tok_list);
2530         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2531 out:
2532         return rc;
2533 }
2534