cryptfs.c revision 8ddbe40a8a8708dac7c472fa8c098c8f7b24534c
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 //SLOGD("crypt_params = %s\n", crypt_params); // Only for debugging, prints the master key! 288 crypt_params += strlen(crypt_params) + 1; 289 crypt_params = (char *) (((unsigned long)crypt_params + 7) & ~8); /* Align to an 8 byte boundary */ 290 tgt->next = crypt_params - buffer; 291 292 if (ioctl(fd, DM_TABLE_LOAD, io)) { 293 SLOGE("Cannot load dm-crypt mapping table.\n"); 294 goto errout; 295 } 296 297 /* Resume this device to activate it */ 298 ioctl_init(io, 4096, name, 0); 299 300 if (ioctl(fd, DM_DEV_SUSPEND, io)) { 301 SLOGE("Cannot resume the dm-crypt device\n"); 302 goto errout; 303 } 304 305 /* We made it here with no errors. Woot! */ 306 retval = 0; 307 308errout: 309 close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */ 310 311 return retval; 312} 313 314static int delete_crypto_blk_dev(char *crypto_blkdev) 315{ 316 int fd; 317 char buffer[DM_CRYPT_BUF_SIZE]; 318 struct dm_ioctl *io; 319 char *name ="datadev"; /* FIX ME: Make me a paraameter */ 320 int retval = -1; 321 322 if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) { 323 SLOGE("Cannot open device-mapper\n"); 324 goto errout; 325 } 326 327 io = (struct dm_ioctl *) buffer; 328 329 ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0); 330 if (ioctl(fd, DM_DEV_REMOVE, io)) { 331 SLOGE("Cannot remove dm-crypt device\n"); 332 goto errout; 333 } 334 335 /* We made it here with no errors. Woot! */ 336 retval = 0; 337 338errout: 339 close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */ 340 341 return retval; 342 343} 344 345#define HASH_COUNT 2000 346#define KEY_LEN_BYTES 16 347#define IV_LEN_BYTES 16 348 349static void pbkdf2(char *passwd, unsigned char *ikey) 350{ 351 unsigned char salt[32] = { 0 }; 352 353 /* To Do: Make a salt based on some immutable data about this device. 354 * IMEI, or MEID, or CPU serial number, or whatever we can find 355 */ 356 /* Turn the password into a key and IV that can decrypt the master key */ 357 PKCS5_PBKDF2_HMAC_SHA1(passwd, strlen(passwd), salt, sizeof(salt), 358 HASH_COUNT, KEY_LEN_BYTES+IV_LEN_BYTES, ikey); 359} 360 361static int encrypt_master_key(char *passwd, unsigned char *decrypted_master_key, 362 unsigned char *encrypted_master_key) 363{ 364 unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ 365 EVP_CIPHER_CTX e_ctx; 366 int encrypted_len, final_len; 367 368 /* Turn the password into a key and IV that can decrypt the master key */ 369 pbkdf2(passwd, ikey); 370 371 /* Initialize the decryption engine */ 372 if (! EVP_EncryptInit(&e_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) { 373 SLOGE("EVP_EncryptInit failed\n"); 374 return -1; 375 } 376 EVP_CIPHER_CTX_set_padding(&e_ctx, 0); /* Turn off padding as our data is block aligned */ 377 378 /* Encrypt the master key */ 379 if (! EVP_EncryptUpdate(&e_ctx, encrypted_master_key, &encrypted_len, 380 decrypted_master_key, KEY_LEN_BYTES)) { 381 SLOGE("EVP_EncryptUpdate failed\n"); 382 return -1; 383 } 384 if (! EVP_EncryptFinal(&e_ctx, encrypted_master_key + encrypted_len, &final_len)) { 385 SLOGE("EVP_EncryptFinal failed\n"); 386 return -1; 387 } 388 389 if (encrypted_len + final_len != KEY_LEN_BYTES) { 390 SLOGE("EVP_Encryption length check failed with %d, %d bytes\n", encrypted_len, final_len); 391 return -1; 392 } else { 393 return 0; 394 } 395} 396 397static int decrypt_master_key(char *passwd, unsigned char *encrypted_master_key, 398 unsigned char *decrypted_master_key) 399{ 400 unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ 401 EVP_CIPHER_CTX d_ctx; 402 int decrypted_len, final_len; 403 404 /* Turn the password into a key and IV that can decrypt the master key */ 405 pbkdf2(passwd, ikey); 406 407 /* Initialize the decryption engine */ 408 if (! EVP_DecryptInit(&d_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) { 409 return -1; 410 } 411 EVP_CIPHER_CTX_set_padding(&d_ctx, 0); /* Turn off padding as our data is block aligned */ 412 /* Decrypt the master key */ 413 if (! EVP_DecryptUpdate(&d_ctx, decrypted_master_key, &decrypted_len, 414 encrypted_master_key, KEY_LEN_BYTES)) { 415 return -1; 416 } 417 if (! EVP_DecryptFinal(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) { 418 return -1; 419 } 420 421 if (decrypted_len + final_len != KEY_LEN_BYTES) { 422 return -1; 423 } else { 424 return 0; 425 } 426} 427 428static int create_encrypted_random_key(char *passwd, unsigned char *master_key) 429{ 430 int fd; 431 unsigned char buf[KEY_LEN_BYTES]; 432 unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */ 433 unsigned char salt[32] = { 0 }; 434 EVP_CIPHER_CTX e_ctx; 435 int encrypted_len, final_len; 436 437 /* Get some random bits for a key */ 438 fd = open("/dev/urandom", O_RDONLY); 439 read(fd, buf, sizeof(buf)); 440 close(fd); 441 442 /* Now encrypt it with the password */ 443 return encrypt_master_key(passwd, buf, master_key); 444} 445 446static int get_orig_mount_parms(char *mount_point, char *fs_type, char *real_blkdev, 447 unsigned long *mnt_flags, char *fs_options) 448{ 449 char mount_point2[32]; 450 char fs_flags[32]; 451 452 property_get("ro.crypto.fs_type", fs_type, ""); 453 property_get("ro.crypto.fs_real_blkdev", real_blkdev, ""); 454 property_get("ro.crypto.fs_mnt_point", mount_point2, ""); 455 property_get("ro.crypto.fs_options", fs_options, ""); 456 property_get("ro.crypto.fs_flags", fs_flags, ""); 457 *mnt_flags = strtol(fs_flags, 0, 0); 458 459 if (strcmp(mount_point, mount_point2)) { 460 /* Consistency check. These should match. If not, something odd happened. */ 461 return -1; 462 } 463 464 return 0; 465} 466 467static int wait_and_unmount(char *mountpoint) 468{ 469 int i, rc; 470#define WAIT_UNMOUNT_COUNT 20 471 472 /* Now umount the tmpfs filesystem */ 473 for (i=0; i<WAIT_UNMOUNT_COUNT; i++) { 474 if (umount(mountpoint)) { 475 sleep(1); 476 i++; 477 } else { 478 break; 479 } 480 } 481 482 if (i < WAIT_UNMOUNT_COUNT) { 483 SLOGD("unmounting %s succeeded\n", mountpoint); 484 rc = 0; 485 } else { 486 SLOGE("unmounting %s failed\n", mountpoint); 487 rc = -1; 488 } 489 490 return rc; 491} 492 493#define DATA_PREP_TIMEOUT 100 494static int prep_data_fs(void) 495{ 496 int i; 497 498 /* Do the prep of the /data filesystem */ 499 property_set("vold.post_fs_data_done", "0"); 500 property_set("vold.decrypt", "trigger_post_fs_data"); 501 SLOGD("Just triggered post_fs_data\n"); 502 503 /* Wait a max of 25 seconds, hopefully it takes much less */ 504 for (i=0; i<DATA_PREP_TIMEOUT; i++) { 505 char p[16];; 506 507 property_get("vold.post_fs_data_done", p, "0"); 508 if (*p == '1') { 509 break; 510 } else { 511 usleep(250000); 512 } 513 } 514 if (i == DATA_PREP_TIMEOUT) { 515 /* Ugh, we failed to prep /data in time. Bail. */ 516 return -1; 517 } else { 518 SLOGD("post_fs_data done\n"); 519 return 0; 520 } 521} 522 523int cryptfs_restart(void) 524{ 525 char fs_type[32]; 526 char real_blkdev[MAXPATHLEN]; 527 char crypto_blkdev[MAXPATHLEN]; 528 char fs_options[256]; 529 unsigned long mnt_flags; 530 struct stat statbuf; 531 int rc = -1, i; 532 533 /* Here is where we shut down the framework. The init scripts 534 * start all services in one of three classes: core, main or late_start. 535 * On boot, we start core and main. Now, we stop main, but not core, 536 * as core includes vold and a few other really important things that 537 * we need to keep running. Once main has stopped, we should be able 538 * to umount the tmpfs /data, then mount the encrypted /data. 539 * We then restart the class main, and also the class late_start. 540 * At the moment, I've only put a few things in late_start that I know 541 * are not needed to bring up the framework, and that also cause problems 542 * with unmounting the tmpfs /data, but I hope to add add more services 543 * to the late_start class as we optimize this to decrease the delay 544 * till the user is asked for the password to the filesystem. 545 */ 546 547 /* The init files are setup to stop the class main when vold.decrypt is 548 * set to trigger_reset_main. 549 */ 550 property_set("vold.decrypt", "trigger_reset_main"); 551 SLOGD("Just asked init to shut down class main\n"); 552 553 /* Now that the framework is shutdown, we should be able to umount() 554 * the tmpfs filesystem, and mount the real one. 555 */ 556 557 property_get("ro.crypto.fs_crypto_blkdev", crypto_blkdev, ""); 558 if (strlen(crypto_blkdev) == 0) { 559 SLOGE("fs_crypto_blkdev not set\n"); 560 return -1; 561 } 562 563 if (! get_orig_mount_parms(DATA_MNT_POINT, fs_type, real_blkdev, &mnt_flags, fs_options)) { 564 SLOGD("Just got orig mount parms\n"); 565 566 if (! (rc = wait_and_unmount(DATA_MNT_POINT)) ) { 567 /* If that succeeded, then mount the decrypted filesystem */ 568 mount(crypto_blkdev, DATA_MNT_POINT, fs_type, mnt_flags, fs_options); 569 570 /* Create necessary paths on /data */ 571 if (prep_data_fs()) { 572 return -1; 573 } 574 575 /* startup service classes main and late_start */ 576 property_set("vold.decrypt", "trigger_restart_framework"); 577 SLOGD("Just triggered restart_framework\n"); 578 579 /* Give it a few moments to get started */ 580 sleep(1); 581 } 582 } 583 584 return rc; 585} 586 587static int test_mount_encrypted_fs(char *passwd, char *mount_point) 588{ 589 struct crypt_mnt_ftr crypt_ftr; 590 /* Allocate enough space for a 256 bit key, but we may use less */ 591 unsigned char encrypted_master_key[32], decrypted_master_key[32]; 592 char crypto_blkdev[MAXPATHLEN]; 593 char real_blkdev[MAXPATHLEN]; 594 char fs_type[32]; 595 char fs_options[256]; 596 char tmp_mount_point[64]; 597 unsigned long mnt_flags; 598 unsigned int orig_failed_decrypt_count; 599 int rc; 600 601 if (get_orig_mount_parms(mount_point, fs_type, real_blkdev, &mnt_flags, fs_options)) { 602 SLOGE("Error reading original mount parms for mount point %s\n", mount_point); 603 return -1; 604 } 605 606 if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key)) { 607 SLOGE("Error getting crypt footer and key\n"); 608 return -1; 609 } 610 SLOGD("crypt_ftr->fs_size = %lld\n", crypt_ftr.fs_size); 611 orig_failed_decrypt_count = crypt_ftr.failed_decrypt_count; 612 613 if (! (crypt_ftr.flags & CRYPT_MNT_KEY_UNENCRYPTED) ) { 614 decrypt_master_key(passwd, encrypted_master_key, decrypted_master_key); 615 } 616 617 if (create_crypto_blk_dev(&crypt_ftr, decrypted_master_key, 618 real_blkdev, crypto_blkdev)) { 619 SLOGE("Error creating decrypted block device\n"); 620 return -1; 621 } 622 623 /* If init detects an encrypted filesystme, it writes a file for each such 624 * encrypted fs into the tmpfs /data filesystem, and then the framework finds those 625 * files and passes that data to me */ 626 /* Create a tmp mount point to try mounting the decryptd fs 627 * Since we're here, the mount_point should be a tmpfs filesystem, so make 628 * a directory in it to test mount the decrypted filesystem. 629 */ 630 sprintf(tmp_mount_point, "%s/tmp_mnt", mount_point); 631 mkdir(tmp_mount_point, 0755); 632 if ( mount(crypto_blkdev, tmp_mount_point, "ext4", MS_RDONLY, "") ) { 633 SLOGE("Error temp mounting decrypted block device\n"); 634 delete_crypto_blk_dev(crypto_blkdev); 635 crypt_ftr.failed_decrypt_count++; 636 } else { 637 /* Success, so just umount and we'll mount it properly when we restart 638 * the framework. 639 */ 640 umount(tmp_mount_point); 641 crypt_ftr.failed_decrypt_count = 0; 642 } 643 644 if (orig_failed_decrypt_count != crypt_ftr.failed_decrypt_count) { 645 put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, 0); 646 } 647 648 if (crypt_ftr.failed_decrypt_count) { 649 /* We failed to mount the device, so return an error */ 650 rc = crypt_ftr.failed_decrypt_count; 651 652 } else { 653 /* Woot! Success! Save the name of the crypto block device 654 * so we can mount it when restarting the framework. 655 */ 656 property_set("ro.crypto.fs_crypto_blkdev", crypto_blkdev); 657 /* Also save a SHA1 of the master key so we can know if we 658 * successfully decrypted the key when we want to change the 659 * password on it. 660 */ 661 SHA1(decrypted_master_key, KEY_LEN_BYTES, saved_key_sha1); 662 key_sha1_saved = 1; 663 rc = 0; 664 } 665 666 return rc; 667} 668 669int cryptfs_check_passwd(char *passwd) 670{ 671 int rc = -1; 672 673 rc = test_mount_encrypted_fs(passwd, DATA_MNT_POINT); 674 675 return rc; 676} 677 678/* Initialize a crypt_mnt_ftr structure. The keysize is 679 * defaulted to 16 bytes, and the filesystem size to 0. 680 * Presumably, at a minimum, the caller will update the 681 * filesystem size and crypto_type_name after calling this function. 682 */ 683static void cryptfs_init_crypt_mnt_ftr(struct crypt_mnt_ftr *ftr) 684{ 685 ftr->magic = CRYPT_MNT_MAGIC; 686 ftr->major_version = 1; 687 ftr->minor_version = 0; 688 ftr->ftr_size = sizeof(struct crypt_mnt_ftr); 689 ftr->flags = 0; 690 ftr->keysize = 16; 691 ftr->spare1 = 0; 692 ftr->fs_size = 0; 693 ftr->failed_decrypt_count = 0; 694 ftr->crypto_type_name[0] = '\0'; 695} 696 697static int cryptfs_enable_wipe(char *crypto_blkdev, off64_t size) 698{ 699 char cmdline[256]; 700 int rc = -1; 701 702 snprintf(cmdline, sizeof(cmdline), "/system/bin/make_ext4fs -a /data -l %lld %s", 703 size * 512, crypto_blkdev); 704 SLOGI("Making empty filesystem with command %s\n", cmdline); 705 if (system(cmdline)) { 706 SLOGE("Error creating empty filesystem on %s\n", crypto_blkdev); 707 } else { 708 SLOGD("Successfully created empty filesystem on %s\n", crypto_blkdev); 709 rc = 0; 710 } 711 712 return rc; 713} 714 715static inline int unix_read(int fd, void* buff, int len) 716{ 717 int ret; 718 do { ret = read(fd, buff, len); } while (ret < 0 && errno == EINTR); 719 return ret; 720} 721 722static inline int unix_write(int fd, const void* buff, int len) 723{ 724 int ret; 725 do { ret = write(fd, buff, len); } while (ret < 0 && errno == EINTR); 726 return ret; 727} 728 729#define CRYPT_INPLACE_BUFSIZE 4096 730#define CRYPT_SECTORS_PER_BUFSIZE (CRYPT_INPLACE_BUFSIZE / 512) 731static int cryptfs_enable_inplace(char *crypto_blkdev, char *real_blkdev, off64_t size) 732{ 733 int realfd, cryptofd; 734 char *buf[CRYPT_INPLACE_BUFSIZE]; 735 int rc = -1; 736 off64_t numblocks, i, remainder; 737 off64_t one_pct, cur_pct, new_pct; 738 739 if ( (realfd = open(real_blkdev, O_RDONLY)) < 0) { 740 SLOGE("Error opening real_blkdev %s for inplace encrypt\n", real_blkdev); 741 return -1; 742 } 743 744 if ( (cryptofd = open(crypto_blkdev, O_WRONLY)) < 0) { 745 SLOGE("Error opening crypto_blkdev %s for inplace encrypt\n", crypto_blkdev); 746 close(realfd); 747 return -1; 748 } 749 750 /* This is pretty much a simple loop of reading 4K, and writing 4K. 751 * The size passed in is the number of 512 byte sectors in the filesystem. 752 * So compute the number of whole 4K blocks we should read/write, 753 * and the remainder. 754 */ 755 numblocks = size / CRYPT_SECTORS_PER_BUFSIZE; 756 remainder = size % CRYPT_SECTORS_PER_BUFSIZE; 757 758 SLOGE("Encrypting filesystem in place..."); 759 760 one_pct = numblocks / 100; 761 cur_pct = 0; 762 /* process the majority of the filesystem in blocks */ 763 for (i=0; i<numblocks; i++) { 764 new_pct = i / one_pct; 765 if (new_pct > cur_pct) { 766 char buf[8]; 767 768 cur_pct = new_pct; 769 snprintf(buf, sizeof(buf), "%lld", cur_pct); 770 property_set("vold.encrypt_progress", buf); 771 } 772 if (unix_read(realfd, buf, CRYPT_INPLACE_BUFSIZE) <= 0) { 773 SLOGE("Error reading real_blkdev %s for inplace encrypt\n", crypto_blkdev); 774 goto errout; 775 } 776 if (unix_write(cryptofd, buf, CRYPT_INPLACE_BUFSIZE) <= 0) { 777 SLOGE("Error writing crypto_blkdev %s for inplace encrypt\n", crypto_blkdev); 778 goto errout; 779 } 780 } 781 782 /* Do any remaining sectors */ 783 for (i=0; i<remainder; i++) { 784 if (unix_read(realfd, buf, 512) <= 0) { 785 SLOGE("Error reading rival sectors from real_blkdev %s for inplace encrypt\n", crypto_blkdev); 786 goto errout; 787 } 788 if (unix_write(cryptofd, buf, 512) <= 0) { 789 SLOGE("Error writing final sectors to crypto_blkdev %s for inplace encrypt\n", crypto_blkdev); 790 goto errout; 791 } 792 } 793 794 property_set("vold.encrypt_progress", "100"); 795 796 rc = 0; 797 798errout: 799 close(realfd); 800 close(cryptofd); 801 802 return rc; 803} 804 805#define CRYPTO_ENABLE_WIPE 1 806#define CRYPTO_ENABLE_INPLACE 2 807 808#define FRAMEWORK_BOOT_WAIT 60 809 810int cryptfs_enable(char *howarg, char *passwd) 811{ 812 int how = 0; 813 char crypto_blkdev[MAXPATHLEN], real_blkdev[MAXPATHLEN]; 814 char fs_type[32], fs_options[256], mount_point[32]; 815 unsigned long mnt_flags, nr_sec; 816 unsigned char master_key[16], decrypted_master_key[16]; 817 int rc=-1, fd, i; 818 struct crypt_mnt_ftr crypt_ftr; 819 char tmpfs_options[80]; 820 821 if (!strcmp(howarg, "wipe")) { 822 how = CRYPTO_ENABLE_WIPE; 823 } else if (! strcmp(howarg, "inplace")) { 824 how = CRYPTO_ENABLE_INPLACE; 825 } else { 826 /* Shouldn't happen, as CommandListener vets the args */ 827 return -1; 828 } 829 830 get_orig_mount_parms(mount_point, fs_type, real_blkdev, &mnt_flags, fs_options); 831 832 /* The init files are setup to stop the class main and late start when 833 * vold sets trigger_shutdown_framework. 834 */ 835 property_set("vold.decrypt", "trigger_shutdown_framework"); 836 SLOGD("Just asked init to shut down class main\n"); 837 838 if (wait_and_unmount("/mnt/sdcard")) { 839 return -1; 840 } 841 842 /* Now unmount the /data partition. */ 843 if (wait_and_unmount(DATA_MNT_POINT)) { 844 return -1; 845 } 846 847 /* Do extra work for a better UX when doing the long inplace encryption */ 848 if (how == CRYPTO_ENABLE_INPLACE) { 849 /* Now that /data is unmounted, we need to mount a tmpfs 850 * /data, set a property saying we're doing inplace encryption, 851 * and restart the framework. 852 */ 853 property_get("ro.crypto.tmpfs_options", tmpfs_options, ""); 854 if (mount("tmpfs", DATA_MNT_POINT, "tmpfs", MS_NOATIME | MS_NOSUID | MS_NODEV, 855 tmpfs_options) < 0) { 856 return -1; 857 } 858 /* Tells the framework that inplace encryption is starting */ 859 property_set("vold.encrypt_progress", "startup"); 860 861 /* restart the framework. */ 862 /* Create necessary paths on /data */ 863 if (prep_data_fs()) { 864 return -1; 865 } 866 867 /* startup service classes main and late_start */ 868 property_set("vold.decrypt", "trigger_restart_min_framework"); 869 SLOGD("Just triggered restart_min_framework\n"); 870 871 /* Wait till the framework is ready */ 872 for (i=0; i<FRAMEWORK_BOOT_WAIT; i++) { 873 char progress_state[32]; 874 875 sleep(1); 876 property_get("vold.encrypt_progress", progress_state, ""); 877 if (! strcmp(progress_state, "ready")) { 878 break; 879 } 880 } 881 if (i == FRAMEWORK_BOOT_WAIT) { 882 /* The framework never rebooted, so abort */ 883 return -1; 884 } 885 /* OK, the framework is restarted and displaying a progress bar, 886 * time to setup an encrypted mapping, and either write a new 887 * filesystem or encrypt in place, updating the progress bar 888 * as we work. 889 */ 890 } 891 892 /* Start the actual work of making an encrypted filesystem */ 893 fd = open(real_blkdev, O_RDONLY); 894 if ( (nr_sec = get_blkdev_size(fd)) == 0) { 895 SLOGE("Cannot get size of block device %s\n", real_blkdev); 896 return -1; 897 } 898 close(fd); 899 900 /* Initialize a crypt_mnt_ftr for the partition */ 901 cryptfs_init_crypt_mnt_ftr(&crypt_ftr); 902 crypt_ftr.fs_size = nr_sec - (CRYPT_FOOTER_OFFSET / 512); 903 strcpy((char *)crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256"); 904 905 /* Make an encrypted master key */ 906 if (create_encrypted_random_key(passwd, master_key)) { 907 SLOGE("Cannot create encrypted master key\n"); 908 return -1; 909 } 910 911 /* Write the key to the end of the partition */ 912 put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, master_key); 913 914 decrypt_master_key(passwd, master_key, decrypted_master_key); 915 create_crypto_blk_dev(&crypt_ftr, decrypted_master_key, real_blkdev, crypto_blkdev); 916 917 if (how == CRYPTO_ENABLE_WIPE) { 918 rc = cryptfs_enable_wipe(crypto_blkdev, crypt_ftr.fs_size); 919 } else if (how == CRYPTO_ENABLE_INPLACE) { 920 rc = cryptfs_enable_inplace(crypto_blkdev, real_blkdev, crypt_ftr.fs_size); 921 } else { 922 /* Shouldn't happen */ 923 SLOGE("cryptfs_enable: internal error, unknown option\n"); 924 return -1; 925 } 926 927 /* Undo the dm-crypt mapping whether we succeed or not */ 928 delete_crypto_blk_dev(crypto_blkdev); 929 930 if (! rc) { 931 /* Success */ 932 sleep(2); /* Give the UI a change to show 100% progress */ 933 sync(); 934 reboot(LINUX_REBOOT_CMD_RESTART); 935 } 936 937 /* Only returns on error */ 938 return rc; 939} 940 941int cryptfs_changepw(char *oldpw, char *newpw) 942{ 943 struct crypt_mnt_ftr crypt_ftr; 944 unsigned char encrypted_master_key[32], decrypted_master_key[32]; 945 unsigned char new_key_sha1[20]; 946 char real_blkdev[MAXPATHLEN]; 947 948 /* This is only allowed after we've successfully decrypted the master key */ 949 if (! key_sha1_saved) { 950 return -1; 951 } 952 953 property_get("ro.crypto.fs_real_blkdev", real_blkdev, ""); 954 if (strlen(real_blkdev) == 0) { 955 return -1; 956 } 957 958 /* get key */ 959 if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key)) { 960 SLOGE("Error getting crypt footer and key\n"); 961 return -1; 962 } 963 964 /* decrypt key with old passwd */ 965 decrypt_master_key(oldpw, encrypted_master_key, decrypted_master_key); 966 967 /* compute sha1 of decrypted key */ 968 SHA1(decrypted_master_key, KEY_LEN_BYTES, new_key_sha1); 969 970 /* If computed sha1 and saved sha1 match, encrypt key with new passwd */ 971 if (! memcmp(saved_key_sha1, new_key_sha1, sizeof(saved_key_sha1))) { 972 /* they match, it's safe to re-encrypt the key */ 973 encrypt_master_key(newpw, decrypted_master_key, encrypted_master_key); 974 975 /* save the key */ 976 put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key); 977 } else { 978 SLOGE("SHA1 mismatch"); 979 return -1; 980 } 981 982 return 0; 983} 984 985