cryptfs.c revision 7df84120b25dca713f623528801385b00208c2aa
1/* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17/* TO DO: 18 * 1. Perhaps keep several copies of the encrypted key, in case something 19 * goes horribly wrong? 20 * 21 */ 22 23#include <sys/types.h> 24#include <sys/stat.h> 25#include <fcntl.h> 26#include <unistd.h> 27#include <stdio.h> 28#include <sys/ioctl.h> 29#include <linux/dm-ioctl.h> 30#include <libgen.h> 31#include <stdlib.h> 32#include <sys/param.h> 33#include <string.h> 34#include <sys/mount.h> 35#include <openssl/evp.h> 36#include <openssl/sha.h> 37#include <errno.h> 38#include <sys/reboot.h> 39#include "cryptfs.h" 40#define LOG_TAG "Cryptfs" 41#include "cutils/log.h" 42#include "cutils/properties.h" 43 44#define DM_CRYPT_BUF_SIZE 4096 45#define DATA_MNT_POINT "/data" 46 47char *me = "cryptfs"; 48 49static unsigned char saved_key_sha1[20] = { '\0' }; 50static int key_sha1_saved = 0; 51 52static void ioctl_init(struct dm_ioctl *io, size_t dataSize, const char *name, unsigned flags) 53{ 54 memset(io, 0, dataSize); 55 io->data_size = dataSize; 56 io->data_start = sizeof(struct dm_ioctl); 57 io->version[0] = 4; 58 io->version[1] = 0; 59 io->version[2] = 0; 60 io->flags = flags; 61 if (name) { 62 strncpy(io->name, name, sizeof(io->name)); 63 } 64} 65 66static unsigned int get_blkdev_size(int fd) 67{ 68 unsigned int nr_sec; 69 70 if ( (ioctl(fd, BLKGETSIZE, &nr_sec)) == -1) { 71 nr_sec = 0; 72 } 73 74 return nr_sec; 75} 76 77/* key can be NULL, in which case just write out the footer. Useful to 78 * update the failed mount count but not change the key. 79 */ 80static int put_crypt_ftr_and_key(char *real_blk_name, struct crypt_mnt_ftr *crypt_ftr, 81 unsigned char *key) 82{ 83 int fd; 84 unsigned int nr_sec, cnt; 85 off64_t off; 86 int rc = -1; 87 88 if ( (fd = open(real_blk_name, O_RDWR)) < 0) { 89 SLOGE("Cannot open real block device %s\n", real_blk_name); 90 return -1; 91 } 92 93 if ( (nr_sec = get_blkdev_size(fd)) == 0) { 94 SLOGE("Cannot get size of block device %s\n", real_blk_name); 95 goto errout; 96 } 97 98 /* If it's an encrypted Android partition, the last 16 Kbytes contain the 99 * encryption info footer and key, and plenty of bytes to spare for future 100 * growth. 101 */ 102 off = ((off64_t)nr_sec * 512) - CRYPT_FOOTER_OFFSET; 103 104 if (lseek64(fd, off, SEEK_SET) == -1) { 105 SLOGE("Cannot seek to real block device footer\n"); 106 goto errout; 107 } 108 109 if ((cnt = write(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr))) != sizeof(struct crypt_mnt_ftr)) { 110 SLOGE("Cannot write real block device footer\n"); 111 goto errout; 112 } 113 114 if (key) { 115 if (crypt_ftr->keysize != 16) { 116 SLOGE("Keysize of %d bits not supported for real block device %s\n", 117 crypt_ftr->keysize * 8, real_blk_name); 118 goto errout; 119 } 120 121 if ( (cnt = write(fd, key, crypt_ftr->keysize)) != crypt_ftr->keysize) { 122 SLOGE("Cannot write key for real block device %s\n", real_blk_name); 123 goto errout; 124 } 125 } 126 127 /* Success! */ 128 rc = 0; 129 130errout: 131 close(fd); 132 return rc; 133 134} 135 136static int get_crypt_ftr_and_key(char *real_blk_name, struct crypt_mnt_ftr *crypt_ftr, 137 unsigned char *key) 138{ 139 int fd; 140 unsigned int nr_sec, cnt; 141 off64_t off; 142 int rc = -1; 143 144 if ( (fd = open(real_blk_name, O_RDWR)) < 0) { 145 SLOGE("Cannot open real block device %s\n", real_blk_name); 146 return -1; 147 } 148 149 if ( (nr_sec = get_blkdev_size(fd)) == 0) { 150 SLOGE("Cannot get size of block device %s\n", real_blk_name); 151 goto errout; 152 } 153 154 /* If it's an encrypted Android partition, the last 16 Kbytes contain the 155 * encryption info footer and key, and plenty of bytes to spare for future 156 * growth. 157 */ 158 off = ((off64_t)nr_sec * 512) - CRYPT_FOOTER_OFFSET; 159 160 if (lseek64(fd, off, SEEK_SET) == -1) { 161 SLOGE("Cannot seek to real block device footer\n"); 162 goto errout; 163 } 164 165 if ( (cnt = read(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr))) != sizeof(struct crypt_mnt_ftr)) { 166 SLOGE("Cannot read real block device footer\n"); 167 goto errout; 168 } 169 170 if (crypt_ftr->magic != CRYPT_MNT_MAGIC) { 171 SLOGE("Bad magic for real block device %s\n", real_blk_name); 172 goto errout; 173 } 174 175 if (crypt_ftr->major_version != 1) { 176 SLOGE("Cannot understand major version %d real block device footer\n", 177 crypt_ftr->major_version); 178 goto errout; 179 } 180 181 if (crypt_ftr->minor_version != 0) { 182 SLOGW("Warning: crypto footer minor version %d, expected 0, continuing...\n", 183 crypt_ftr->minor_version); 184 } 185 186 if (crypt_ftr->ftr_size > sizeof(struct crypt_mnt_ftr)) { 187 /* the footer size is bigger than we expected. 188 * Skip to it's stated end so we can read the key. 189 */ 190 if (lseek(fd, crypt_ftr->ftr_size - sizeof(struct crypt_mnt_ftr), SEEK_CUR) == -1) { 191 SLOGE("Cannot seek to start of key\n"); 192 goto errout; 193 } 194 } 195 196 if (crypt_ftr->keysize != 16) { 197 SLOGE("Keysize of %d bits not supported for real block device %s\n", 198 crypt_ftr->keysize * 8, real_blk_name); 199 goto errout; 200 } 201 202 if ( (cnt = read(fd, key, crypt_ftr->keysize)) != crypt_ftr->keysize) { 203 SLOGE("Cannot read key for real block device %s\n", real_blk_name); 204 goto errout; 205 } 206 207 /* Success! */ 208 rc = 0; 209 210errout: 211 close(fd); 212 return rc; 213} 214 215/* Convert a binary key of specified length into an ascii hex string equivalent, 216 * without the leading 0x and with null termination 217 */ 218void convert_key_to_hex_ascii(unsigned char *master_key, unsigned int keysize, 219 char *master_key_ascii) 220{ 221 unsigned int i, a; 222 unsigned char nibble; 223 224 for (i=0, a=0; i<keysize; i++, a+=2) { 225 /* For each byte, write out two ascii hex digits */ 226 nibble = (master_key[i] >> 4) & 0xf; 227 master_key_ascii[a] = nibble + (nibble > 9 ? 0x37 : 0x30); 228 229 nibble = master_key[i] & 0xf; 230 master_key_ascii[a+1] = nibble + (nibble > 9 ? 0x37 : 0x30); 231 } 232 233 /* Add the null termination */ 234 master_key_ascii[a] = '\0'; 235 236} 237 238static int create_crypto_blk_dev(struct crypt_mnt_ftr *crypt_ftr, unsigned char *master_key, 239 char *real_blk_name, char *crypto_blk_name) 240{ 241 char buffer[DM_CRYPT_BUF_SIZE]; 242 char master_key_ascii[129]; /* Large enough to hold 512 bit key and null */ 243 char *crypt_params; 244 struct dm_ioctl *io; 245 struct dm_target_spec *tgt; 246 unsigned int minor; 247 int fd; 248 int retval = -1; 249 char *name ="datadev"; /* FIX ME: Make me a parameter */ 250 251 if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) { 252 SLOGE("Cannot open device-mapper\n"); 253 goto errout; 254 } 255 256 io = (struct dm_ioctl *) buffer; 257 258 ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); 259 if (ioctl(fd, DM_DEV_CREATE, io)) { 260 SLOGE("Cannot create dm-crypt device\n"); 261 goto errout; 262 } 263 264 /* Get the device status, in particular, the name of it's device file */ 265 ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); 266 if (ioctl(fd, DM_DEV_STATUS, io)) { 267 SLOGE("Cannot retrieve dm-crypt device status\n"); 268 goto errout; 269 } 270 minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00); 271 snprintf(crypto_blk_name, MAXPATHLEN, "/dev/block/dm-%u", minor); 272 273 /* Load the mapping table for this device */ 274 tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)]; 275 276 ioctl_init(io, 4096, name, 0); 277 io->target_count = 1; 278 tgt->status = 0; 279 tgt->sector_start = 0; 280 tgt->length = crypt_ftr->fs_size; 281 strcpy(tgt->target_type, "crypt"); 282 283 crypt_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec); 284 convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii); 285 sprintf(crypt_params, "%s %s 0 %s 0", crypt_ftr->crypto_type_name, 286 master_key_ascii, real_blk_name); 287 crypt_params += strlen(crypt_params) + 1; 288 crypt_params = (char *) (((unsigned long)crypt_params + 7) & ~8); /* Align to an 8 byte boundary */ 289 tgt->next = crypt_params - buffer; 290 291 if (ioctl(fd, DM_TABLE_LOAD, io)) { 292 SLOGE("Cannot load dm-crypt mapping table.\n"); 293 goto errout; 294 } 295 296 /* Resume this device to activate it */ 297 ioctl_init(io, 4096, name, 0); 298 299 if (ioctl(fd, DM_DEV_SUSPEND, io)) { 300 SLOGE("Cannot resume the dm-crypt device\n"); 301 goto errout; 302 } 303 304 /* We made it here with no errors. Woot! */ 305 retval = 0; 306 307errout: 308 close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */ 309 310 return retval; 311} 312 313static int delete_crypto_blk_dev(char *crypto_blkdev) 314{ 315 int fd; 316 char buffer[DM_CRYPT_BUF_SIZE]; 317 struct dm_ioctl *io; 318 char *name ="datadev"; /* FIX ME: Make me a paraameter */ 319 int retval = -1; 320 321 if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) { 322 SLOGE("Cannot open device-mapper\n"); 323 goto errout; 324 } 325 326 io = (struct dm_ioctl *) buffer; 327 328 ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); 329 if (ioctl(fd, DM_DEV_REMOVE, io)) { 330 SLOGE("Cannot remove dm-crypt device\n"); 331 goto errout; 332 } 333 334 /* We made it here with no errors. Woot! */ 335 retval = 0; 336 337errout: 338 close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */ 339 340 return retval; 341 342} 343 344#define HASH_COUNT 2000 345#define KEY_LEN_BYTES 16 346#define IV_LEN_BYTES 16 347 348static void pbkdf2(char *passwd, unsigned char *ikey) 349{ 350 unsigned char salt[32] = { 0 }; 351 352 /* To Do: Make a salt based on some immutable data about this device. 353 * IMEI, or MEID, or CPU serial number, or whatever we can find 354 */ 355 /* Turn the password into a key and IV that can decrypt the master key */ 356 PKCS5_PBKDF2_HMAC_SHA1(passwd, strlen(passwd), salt, sizeof(salt), 357 HASH_COUNT, KEY_LEN_BYTES+IV_LEN_BYTES, ikey); 358} 359 360static int encrypt_master_key(char *passwd, unsigned char *decrypted_master_key, 361 unsigned char *encrypted_master_key) 362{ 363 unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ 364 EVP_CIPHER_CTX e_ctx; 365 int encrypted_len, final_len; 366 367 /* Turn the password into a key and IV that can decrypt the master key */ 368 pbkdf2(passwd, ikey); 369 370 /* Initialize the decryption engine */ 371 if (! EVP_EncryptInit(&e_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) { 372 SLOGE("EVP_EncryptInit failed\n"); 373 return -1; 374 } 375 EVP_CIPHER_CTX_set_padding(&e_ctx, 0); /* Turn off padding as our data is block aligned */ 376 377 /* Encrypt the master key */ 378 if (! EVP_EncryptUpdate(&e_ctx, encrypted_master_key, &encrypted_len, 379 decrypted_master_key, KEY_LEN_BYTES)) { 380 SLOGE("EVP_EncryptUpdate failed\n"); 381 return -1; 382 } 383 if (! EVP_EncryptFinal(&e_ctx, encrypted_master_key + encrypted_len, &final_len)) { 384 SLOGE("EVP_EncryptFinal failed\n"); 385 return -1; 386 } 387 388 if (encrypted_len + final_len != KEY_LEN_BYTES) { 389 SLOGE("EVP_Encryption length check failed with %d, %d bytes\n", encrypted_len, final_len); 390 return -1; 391 } else { 392 return 0; 393 } 394} 395 396static int decrypt_master_key(char *passwd, unsigned char *encrypted_master_key, 397 unsigned char *decrypted_master_key) 398{ 399 unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ 400 EVP_CIPHER_CTX d_ctx; 401 int decrypted_len, final_len; 402 403 /* Turn the password into a key and IV that can decrypt the master key */ 404 pbkdf2(passwd, ikey); 405 406 /* Initialize the decryption engine */ 407 if (! EVP_DecryptInit(&d_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) { 408 return -1; 409 } 410 EVP_CIPHER_CTX_set_padding(&d_ctx, 0); /* Turn off padding as our data is block aligned */ 411 /* Decrypt the master key */ 412 if (! EVP_DecryptUpdate(&d_ctx, decrypted_master_key, &decrypted_len, 413 encrypted_master_key, KEY_LEN_BYTES)) { 414 return -1; 415 } 416 if (! EVP_DecryptFinal(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) { 417 return -1; 418 } 419 420 if (decrypted_len + final_len != KEY_LEN_BYTES) { 421 return -1; 422 } else { 423 return 0; 424 } 425} 426 427static int create_encrypted_random_key(char *passwd, unsigned char *master_key) 428{ 429 int fd; 430 unsigned char buf[KEY_LEN_BYTES]; 431 unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ 432 unsigned char salt[32] = { 0 }; 433 EVP_CIPHER_CTX e_ctx; 434 int encrypted_len, final_len; 435 436 /* Get some random bits for a key */ 437 fd = open("/dev/urandom", O_RDONLY); 438 read(fd, buf, sizeof(buf)); 439 close(fd); 440 441 /* Now encrypt it with the password */ 442 return encrypt_master_key(passwd, buf, master_key); 443} 444 445static int get_orig_mount_parms(char *mount_point, char *fs_type, char *real_blkdev, 446 unsigned long *mnt_flags, char *fs_options) 447{ 448 char mount_point2[32]; 449 char fs_flags[32]; 450 451 property_get("ro.crypto.fs_type", fs_type, ""); 452 property_get("ro.crypto.fs_real_blkdev", real_blkdev, ""); 453 property_get("ro.crypto.fs_mnt_point", mount_point2, ""); 454 property_get("ro.crypto.fs_options", fs_options, ""); 455 property_get("ro.crypto.fs_flags", fs_flags, ""); 456 *mnt_flags = strtol(fs_flags, 0, 0); 457 458 if (strcmp(mount_point, mount_point2)) { 459 /* Consistency check. These should match. If not, something odd happened. */ 460 return -1; 461 } 462 463 return 0; 464} 465 466static int wait_and_unmount(char *mountpoint) 467{ 468 int i, rc; 469#define WAIT_UNMOUNT_COUNT 20 470 471 /* Now umount the tmpfs filesystem */ 472 for (i=0; i<WAIT_UNMOUNT_COUNT; i++) { 473 if (umount(mountpoint)) { 474 sleep(1); 475 i++; 476 } else { 477 break; 478 } 479 } 480 481 if (i < WAIT_UNMOUNT_COUNT) { 482 SLOGD("unmounting %s succeeded\n", mountpoint); 483 rc = 0; 484 } else { 485 SLOGE("unmounting %s failed\n", mountpoint); 486 rc = -1; 487 } 488 489 return rc; 490} 491 492#define DATA_PREP_TIMEOUT 100 493static int prep_data_fs(void) 494{ 495 int i; 496 497 /* Do the prep of the /data filesystem */ 498 property_set("vold.post_fs_data_done", "0"); 499 property_set("vold.decrypt", "trigger_post_fs_data"); 500 SLOGD("Just triggered post_fs_data\n"); 501 502 /* Wait a max of 25 seconds, hopefully it takes much less */ 503 for (i=0; i<DATA_PREP_TIMEOUT; i++) { 504 char p[16];; 505 506 property_get("vold.post_fs_data_done", p, "0"); 507 if (*p == '1') { 508 break; 509 } else { 510 usleep(250000); 511 } 512 } 513 if (i == DATA_PREP_TIMEOUT) { 514 /* Ugh, we failed to prep /data in time. Bail. */ 515 return -1; 516 } else { 517 SLOGD("post_fs_data done\n"); 518 return 0; 519 } 520} 521 522int cryptfs_restart(void) 523{ 524 char fs_type[32]; 525 char real_blkdev[MAXPATHLEN]; 526 char crypto_blkdev[MAXPATHLEN]; 527 char fs_options[256]; 528 unsigned long mnt_flags; 529 struct stat statbuf; 530 int rc = -1, i; 531 532 /* Here is where we shut down the framework. The init scripts 533 * start all services in one of three classes: core, main or late_start. 534 * On boot, we start core and main. Now, we stop main, but not core, 535 * as core includes vold and a few other really important things that 536 * we need to keep running. Once main has stopped, we should be able 537 * to umount the tmpfs /data, then mount the encrypted /data. 538 * We then restart the class main, and also the class late_start. 539 * At the moment, I've only put a few things in late_start that I know 540 * are not needed to bring up the framework, and that also cause problems 541 * with unmounting the tmpfs /data, but I hope to add add more services 542 * to the late_start class as we optimize this to decrease the delay 543 * till the user is asked for the password to the filesystem. 544 */ 545 546 /* The init files are setup to stop the class main when vold.decrypt is 547 * set to trigger_reset_main. 548 */ 549 property_set("vold.decrypt", "trigger_reset_main"); 550 SLOGD("Just asked init to shut down class main\n"); 551 552 /* Now that the framework is shutdown, we should be able to umount() 553 * the tmpfs filesystem, and mount the real one. 554 */ 555 556 property_get("ro.crypto.fs_crypto_blkdev", crypto_blkdev, ""); 557 if (strlen(crypto_blkdev) == 0) { 558 SLOGE("fs_crypto_blkdev not set\n"); 559 return -1; 560 } 561 562 if (! get_orig_mount_parms(DATA_MNT_POINT, fs_type, real_blkdev, &mnt_flags, fs_options)) { 563 SLOGD("Just got orig mount parms\n"); 564 565 if (! (rc = wait_and_unmount(DATA_MNT_POINT)) ) { 566 /* If that succeeded, then mount the decrypted filesystem */ 567 mount(crypto_blkdev, DATA_MNT_POINT, fs_type, mnt_flags, fs_options); 568 569 /* Create necessary paths on /data */ 570 if (prep_data_fs()) { 571 return -1; 572 } 573 574 /* startup service classes main and late_start */ 575 property_set("vold.decrypt", "trigger_restart_framework"); 576 SLOGD("Just triggered restart_framework\n"); 577 578 /* Give it a few moments to get started */ 579 sleep(1); 580 } 581 } 582 583 return rc; 584} 585 586static int test_mount_encrypted_fs(char *passwd, char *mount_point) 587{ 588 struct crypt_mnt_ftr crypt_ftr; 589 /* Allocate enough space for a 256 bit key, but we may use less */ 590 unsigned char encrypted_master_key[32], decrypted_master_key[32]; 591 char crypto_blkdev[MAXPATHLEN]; 592 char real_blkdev[MAXPATHLEN]; 593 char fs_type[32]; 594 char fs_options[256]; 595 char tmp_mount_point[64]; 596 unsigned long mnt_flags; 597 unsigned int orig_failed_decrypt_count; 598 int rc; 599 600 if (get_orig_mount_parms(mount_point, fs_type, real_blkdev, &mnt_flags, fs_options)) { 601 SLOGE("Error reading original mount parms for mount point %s\n", mount_point); 602 return -1; 603 } 604 605 if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key)) { 606 SLOGE("Error getting crypt footer and key\n"); 607 return -1; 608 } 609 SLOGD("crypt_ftr->fs_size = %lld\n", crypt_ftr.fs_size); 610 orig_failed_decrypt_count = crypt_ftr.failed_decrypt_count; 611 612 if (! (crypt_ftr.flags & CRYPT_MNT_KEY_UNENCRYPTED) ) { 613 decrypt_master_key(passwd, encrypted_master_key, decrypted_master_key); 614 } 615 616 if (create_crypto_blk_dev(&crypt_ftr, decrypted_master_key, 617 real_blkdev, crypto_blkdev)) { 618 SLOGE("Error creating decrypted block device\n"); 619 return -1; 620 } 621 622 /* If init detects an encrypted filesystme, it writes a file for each such 623 * encrypted fs into the tmpfs /data filesystem, and then the framework finds those 624 * files and passes that data to me */ 625 /* Create a tmp mount point to try mounting the decryptd fs 626 * Since we're here, the mount_point should be a tmpfs filesystem, so make 627 * a directory in it to test mount the decrypted filesystem. 628 */ 629 sprintf(tmp_mount_point, "%s/tmp_mnt", mount_point); 630 mkdir(tmp_mount_point, 0755); 631 if ( mount(crypto_blkdev, tmp_mount_point, "ext4", MS_RDONLY, "") ) { 632 SLOGE("Error temp mounting decrypted block device\n"); 633 delete_crypto_blk_dev(crypto_blkdev); 634 crypt_ftr.failed_decrypt_count++; 635 } else { 636 /* Success, so just umount and we'll mount it properly when we restart 637 * the framework. 638 */ 639 umount(tmp_mount_point); 640 crypt_ftr.failed_decrypt_count = 0; 641 } 642 643 if (orig_failed_decrypt_count != crypt_ftr.failed_decrypt_count) { 644 put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, 0); 645 } 646 647 if (crypt_ftr.failed_decrypt_count) { 648 /* We failed to mount the device, so return an error */ 649 rc = crypt_ftr.failed_decrypt_count; 650 651 } else { 652 /* Woot! Success! Save the name of the crypto block device 653 * so we can mount it when restarting the framework. 654 */ 655 property_set("ro.crypto.fs_crypto_blkdev", crypto_blkdev); 656 /* Also save a SHA1 of the master key so we can know if we 657 * successfully decrypted the key when we want to change the 658 * password on it. 659 */ 660 SHA1(decrypted_master_key, KEY_LEN_BYTES, saved_key_sha1); 661 key_sha1_saved = 1; 662 rc = 0; 663 } 664 665 return rc; 666} 667 668int cryptfs_check_passwd(char *passwd) 669{ 670 int rc = -1; 671 672 rc = test_mount_encrypted_fs(passwd, DATA_MNT_POINT); 673 674 return rc; 675} 676 677/* Initialize a crypt_mnt_ftr structure. The keysize is 678 * defaulted to 16 bytes, and the filesystem size to 0. 679 * Presumably, at a minimum, the caller will update the 680 * filesystem size and crypto_type_name after calling this function. 681 */ 682static void cryptfs_init_crypt_mnt_ftr(struct crypt_mnt_ftr *ftr) 683{ 684 ftr->magic = CRYPT_MNT_MAGIC; 685 ftr->major_version = 1; 686 ftr->minor_version = 0; 687 ftr->ftr_size = sizeof(struct crypt_mnt_ftr); 688 ftr->flags = 0; 689 ftr->keysize = 16; 690 ftr->spare1 = 0; 691 ftr->fs_size = 0; 692 ftr->failed_decrypt_count = 0; 693 ftr->crypto_type_name[0] = '\0'; 694} 695 696static int cryptfs_enable_wipe(char *crypto_blkdev, off64_t size) 697{ 698 char cmdline[256]; 699 int rc = -1; 700 701 snprintf(cmdline, sizeof(cmdline), "/system/bin/make_ext4fs -a /data -l %lld %s", 702 size * 512, crypto_blkdev); 703 SLOGI("Making empty filesystem with command %s\n", cmdline); 704 if (system(cmdline)) { 705 SLOGE("Error creating empty filesystem on %s\n", crypto_blkdev); 706 } else { 707 SLOGD("Successfully created empty filesystem on %s\n", crypto_blkdev); 708 rc = 0; 709 } 710 711 return rc; 712} 713 714static inline int unix_read(int fd, void* buff, int len) 715{ 716 int ret; 717 do { ret = read(fd, buff, len); } while (ret < 0 && errno == EINTR); 718 return ret; 719} 720 721static inline int unix_write(int fd, const void* buff, int len) 722{ 723 int ret; 724 do { ret = write(fd, buff, len); } while (ret < 0 && errno == EINTR); 725 return ret; 726} 727 728#define CRYPT_INPLACE_BUFSIZE 4096 729#define CRYPT_SECTORS_PER_BUFSIZE (CRYPT_INPLACE_BUFSIZE / 512) 730static int cryptfs_enable_inplace(char *crypto_blkdev, char *real_blkdev, off64_t size) 731{ 732 int realfd, cryptofd; 733 char *buf[CRYPT_INPLACE_BUFSIZE]; 734 int rc = -1; 735 off64_t numblocks, i, remainder; 736 off64_t one_pct, cur_pct, new_pct; 737 738 if ( (realfd = open(real_blkdev, O_RDONLY)) < 0) { 739 SLOGE("Error opening real_blkdev %s for inplace encrypt\n", real_blkdev); 740 return -1; 741 } 742 743 if ( (cryptofd = open(crypto_blkdev, O_WRONLY)) < 0) { 744 SLOGE("Error opening crypto_blkdev %s for inplace encrypt\n", crypto_blkdev); 745 close(realfd); 746 return -1; 747 } 748 749 /* This is pretty much a simple loop of reading 4K, and writing 4K. 750 * The size passed in is the number of 512 byte sectors in the filesystem. 751 * So compute the number of whole 4K blocks we should read/write, 752 * and the remainder. 753 */ 754 numblocks = size / CRYPT_SECTORS_PER_BUFSIZE; 755 remainder = size % CRYPT_SECTORS_PER_BUFSIZE; 756 757 SLOGE("Encrypting filesystem in place..."); 758 759 one_pct = numblocks / 100; 760 cur_pct = 0; 761 /* process the majority of the filesystem in blocks */ 762 for (i=0; i<numblocks; i++) { 763 new_pct = i / one_pct; 764 if (new_pct > cur_pct) { 765 char buf[8]; 766 767 cur_pct = new_pct; 768 snprintf(buf, sizeof(buf), "%lld", cur_pct); 769 property_set("vold.encrypt_progress", buf); 770 } 771 if (unix_read(realfd, buf, CRYPT_INPLACE_BUFSIZE) <= 0) { 772 SLOGE("Error reading real_blkdev %s for inplace encrypt\n", crypto_blkdev); 773 goto errout; 774 } 775 if (unix_write(cryptofd, buf, CRYPT_INPLACE_BUFSIZE) <= 0) { 776 SLOGE("Error writing crypto_blkdev %s for inplace encrypt\n", crypto_blkdev); 777 goto errout; 778 } 779 } 780 781 /* Do any remaining sectors */ 782 for (i=0; i<remainder; i++) { 783 if (unix_read(realfd, buf, 512) <= 0) { 784 SLOGE("Error reading rival sectors from real_blkdev %s for inplace encrypt\n", crypto_blkdev); 785 goto errout; 786 } 787 if (unix_write(cryptofd, buf, 512) <= 0) { 788 SLOGE("Error writing final sectors to crypto_blkdev %s for inplace encrypt\n", crypto_blkdev); 789 goto errout; 790 } 791 } 792 793 property_set("vold.encrypt_progress", "100"); 794 795 rc = 0; 796 797errout: 798 close(realfd); 799 close(cryptofd); 800 801 return rc; 802} 803 804#define CRYPTO_ENABLE_WIPE 1 805#define CRYPTO_ENABLE_INPLACE 2 806 807#define FRAMEWORK_BOOT_WAIT 60 808 809int cryptfs_enable(char *howarg, char *passwd) 810{ 811 int how = 0; 812 char crypto_blkdev[MAXPATHLEN], real_blkdev[MAXPATHLEN]; 813 char fs_type[32], fs_options[256], mount_point[32]; 814 unsigned long mnt_flags, nr_sec; 815 unsigned char master_key[16], decrypted_master_key[16]; 816 int rc=-1, fd, i; 817 struct crypt_mnt_ftr crypt_ftr; 818 char tmpfs_options[80]; 819 820 if (!strcmp(howarg, "wipe")) { 821 how = CRYPTO_ENABLE_WIPE; 822 } else if (! strcmp(howarg, "inplace")) { 823 how = CRYPTO_ENABLE_INPLACE; 824 } else { 825 /* Shouldn't happen, as CommandListener vets the args */ 826 return -1; 827 } 828 829 get_orig_mount_parms(mount_point, fs_type, real_blkdev, &mnt_flags, fs_options); 830 831 /* The init files are setup to stop the class main and late start when 832 * vold sets trigger_shutdown_framework. 833 */ 834 property_set("vold.decrypt", "trigger_shutdown_framework"); 835 SLOGD("Just asked init to shut down class main\n"); 836 837 if (wait_and_unmount("/mnt/sdcard")) { 838 return -1; 839 } 840 841 /* Now unmount the /data partition. */ 842 if (wait_and_unmount(DATA_MNT_POINT)) { 843 return -1; 844 } 845 846 /* Do extra work for a better UX when doing the long inplace encryption */ 847 if (how == CRYPTO_ENABLE_INPLACE) { 848 /* Now that /data is unmounted, we need to mount a tmpfs 849 * /data, set a property saying we're doing inplace encryption, 850 * and restart the framework. 851 */ 852 property_get("ro.crypto.tmpfs_options", tmpfs_options, ""); 853 if (mount("tmpfs", DATA_MNT_POINT, "tmpfs", MS_NOATIME | MS_NOSUID | MS_NODEV, 854 tmpfs_options) < 0) { 855 return -1; 856 } 857 /* Tells the framework that inplace encryption is starting */ 858 property_set("vold.encrypt_progress", "0"); 859 860 /* restart the framework. */ 861 /* Create necessary paths on /data */ 862 if (prep_data_fs()) { 863 return -1; 864 } 865 866 /* startup service classes main and late_start */ 867 property_set("vold.decrypt", "trigger_restart_min_framework"); 868 SLOGD("Just triggered restart_min_framework\n"); 869 870 /* OK, the framework is restarted and will soon be showing a 871 * progress bar. Time to setup an encrypted mapping, and 872 * either write a new filesystem, or encrypt in place updating 873 * the progress bar as we work. 874 */ 875 } 876 877 /* Start the actual work of making an encrypted filesystem */ 878 fd = open(real_blkdev, O_RDONLY); 879 if ( (nr_sec = get_blkdev_size(fd)) == 0) { 880 SLOGE("Cannot get size of block device %s\n", real_blkdev); 881 return -1; 882 } 883 close(fd); 884 885 /* Initialize a crypt_mnt_ftr for the partition */ 886 cryptfs_init_crypt_mnt_ftr(&crypt_ftr); 887 crypt_ftr.fs_size = nr_sec - (CRYPT_FOOTER_OFFSET / 512); 888 strcpy((char *)crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256"); 889 890 /* Make an encrypted master key */ 891 if (create_encrypted_random_key(passwd, master_key)) { 892 SLOGE("Cannot create encrypted master key\n"); 893 return -1; 894 } 895 896 /* Write the key to the end of the partition */ 897 put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, master_key); 898 899 decrypt_master_key(passwd, master_key, decrypted_master_key); 900 create_crypto_blk_dev(&crypt_ftr, decrypted_master_key, real_blkdev, crypto_blkdev); 901 902 if (how == CRYPTO_ENABLE_WIPE) { 903 rc = cryptfs_enable_wipe(crypto_blkdev, crypt_ftr.fs_size); 904 } else if (how == CRYPTO_ENABLE_INPLACE) { 905 rc = cryptfs_enable_inplace(crypto_blkdev, real_blkdev, crypt_ftr.fs_size); 906 } else { 907 /* Shouldn't happen */ 908 SLOGE("cryptfs_enable: internal error, unknown option\n"); 909 return -1; 910 } 911 912 /* Undo the dm-crypt mapping whether we succeed or not */ 913 delete_crypto_blk_dev(crypto_blkdev); 914 915 if (! rc) { 916 /* Success */ 917 sleep(2); /* Give the UI a change to show 100% progress */ 918 sync(); 919 reboot(LINUX_REBOOT_CMD_RESTART); 920 } 921 922 /* Only returns on error */ 923 return rc; 924} 925 926int cryptfs_changepw(char *oldpw, char *newpw) 927{ 928 struct crypt_mnt_ftr crypt_ftr; 929 unsigned char encrypted_master_key[32], decrypted_master_key[32]; 930 unsigned char new_key_sha1[20]; 931 char real_blkdev[MAXPATHLEN]; 932 933 /* This is only allowed after we've successfully decrypted the master key */ 934 if (! key_sha1_saved) { 935 SLOGE("Key not saved"); 936 return -1; 937 } 938 939 property_get("ro.crypto.fs_real_blkdev", real_blkdev, ""); 940 if (strlen(real_blkdev) == 0) { 941 SLOGE("Can't find real blkdev"); 942 return -1; 943 } 944 945 /* get key */ 946 if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key)) { 947 SLOGE("Error getting crypt footer and key"); 948 return -1; 949 } 950 951 /* decrypt key with old passwd */ 952 decrypt_master_key(oldpw, encrypted_master_key, decrypted_master_key); 953 954 /* compute sha1 of decrypted key */ 955 SHA1(decrypted_master_key, KEY_LEN_BYTES, new_key_sha1); 956 957 /* If computed sha1 and saved sha1 match, encrypt key with new passwd */ 958 if (! memcmp(saved_key_sha1, new_key_sha1, sizeof(saved_key_sha1))) { 959 /* they match, it's safe to re-encrypt the key */ 960 encrypt_master_key(newpw, decrypted_master_key, encrypted_master_key); 961 962 /* save the key */ 963 put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key); 964 } else { 965 SLOGE("SHA1 mismatch"); 966 return -1; 967 } 968 969 return 0; 970} 971 972