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platform_system_vold/cryptfs.c
Ken Sumrall 9dedfd473d Fix encryption on certain devices 
There is a race in the encryption code that after it accepts the
decryption password, it tells init to kill all the processes in
class "main", then it mounts the decrypted filesystem, preps it,
and restarts the framework.  For an unknown reason on some devices,
the new framework sometimes starts up before init has killed and
reaped all the old processes.  The proper fix is to make the killing
of the old framework synchronous, so vold waits till all the
processes have died.  But with factory rom a few days away, the
much more pragmatic solution of adding a sleep of 1 second after
telling init to kill the old framework will suffice.

Bug: 7271212
Change-Id: Ie971cd04abbc6f3f6500b4acd79d3b3b26d9561c
2012-10-09 14:30:00 -07:00

1471 lines
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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* TO DO:
* 1. Perhaps keep several copies of the encrypted key, in case something
* goes horribly wrong?
*
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/dm-ioctl.h>
#include <libgen.h>
#include <stdlib.h>
#include <sys/param.h>
#include <string.h>
#include <sys/mount.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <errno.h>
#include <cutils/android_reboot.h>
#include <ext4.h>
#include <linux/kdev_t.h>
#include <fs_mgr.h>
#include "cryptfs.h"
#define LOG_TAG "Cryptfs"
#include "cutils/android_reboot.h"
#include "cutils/log.h"
#include "cutils/properties.h"
#include "hardware_legacy/power.h"
#include "VolumeManager.h"
#define DM_CRYPT_BUF_SIZE 4096
#define DATA_MNT_POINT "/data"
#define HASH_COUNT 2000
#define KEY_LEN_BYTES 16
#define IV_LEN_BYTES 16
#define KEY_IN_FOOTER "footer"
#define EXT4_FS 1
#define FAT_FS 2
#define TABLE_LOAD_RETRIES 10
char *me = "cryptfs";
static unsigned char saved_master_key[KEY_LEN_BYTES];
static char *saved_data_blkdev;
static char *saved_mount_point;
static int master_key_saved = 0;
#define FSTAB_PREFIX "/fstab."
static char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
static void ioctl_init(struct dm_ioctl *io, size_t dataSize, const char *name, unsigned flags)
{
memset(io, 0, dataSize);
io->data_size = dataSize;
io->data_start = sizeof(struct dm_ioctl);
io->version[0] = 4;
io->version[1] = 0;
io->version[2] = 0;
io->flags = flags;
if (name) {
strncpy(io->name, name, sizeof(io->name));
}
}
static unsigned int get_fs_size(char *dev)
{
int fd, block_size;
struct ext4_super_block sb;
off64_t len;
if ((fd = open(dev, O_RDONLY)) < 0) {
SLOGE("Cannot open device to get filesystem size ");
return 0;
}
if (lseek64(fd, 1024, SEEK_SET) < 0) {
SLOGE("Cannot seek to superblock");
return 0;
}
if (read(fd, &sb, sizeof(sb)) != sizeof(sb)) {
SLOGE("Cannot read superblock");
return 0;
}
close(fd);
block_size = 1024 << sb.s_log_block_size;
/* compute length in bytes */
len = ( ((off64_t)sb.s_blocks_count_hi << 32) + sb.s_blocks_count_lo) * block_size;
/* return length in sectors */
return (unsigned int) (len / 512);
}
static unsigned int get_blkdev_size(int fd)
{
unsigned int nr_sec;
if ( (ioctl(fd, BLKGETSIZE, &nr_sec)) == -1) {
nr_sec = 0;
}
return nr_sec;
}
/* Get and cache the name of the fstab file so we don't
* keep talking over the socket to the property service.
*/
static char *get_fstab_filename(void)
{
if (fstab_filename[0] == 0) {
strcpy(fstab_filename, FSTAB_PREFIX);
property_get("ro.hardware", fstab_filename + sizeof(FSTAB_PREFIX) - 1, "");
}
return fstab_filename;
}
/* key or salt can be NULL, in which case just skip writing that value. Useful to
* update the failed mount count but not change the key.
*/
static int put_crypt_ftr_and_key(char *real_blk_name, struct crypt_mnt_ftr *crypt_ftr,
unsigned char *key, unsigned char *salt)
{
int fd;
unsigned int nr_sec, cnt;
off64_t off;
int rc = -1;
char *fname;
char key_loc[PROPERTY_VALUE_MAX];
struct stat statbuf;
fs_mgr_get_crypt_info(get_fstab_filename(), key_loc, 0, sizeof(key_loc));
if (!strcmp(key_loc, KEY_IN_FOOTER)) {
fname = real_blk_name;
if ( (fd = open(fname, O_RDWR)) < 0) {
SLOGE("Cannot open real block device %s\n", fname);
return -1;
}
if ( (nr_sec = get_blkdev_size(fd)) == 0) {
SLOGE("Cannot get size of block device %s\n", fname);
goto errout;
}
/* If it's an encrypted Android partition, the last 16 Kbytes contain the
* encryption info footer and key, and plenty of bytes to spare for future
* growth.
*/
off = ((off64_t)nr_sec * 512) - CRYPT_FOOTER_OFFSET;
if (lseek64(fd, off, SEEK_SET) == -1) {
SLOGE("Cannot seek to real block device footer\n");
goto errout;
}
} else if (key_loc[0] == '/') {
fname = key_loc;
if ( (fd = open(fname, O_RDWR | O_CREAT, 0600)) < 0) {
SLOGE("Cannot open footer file %s\n", fname);
return -1;
}
} else {
SLOGE("Unexpected value for crypto key location\n");
return -1;;
}
if ((cnt = write(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr))) != sizeof(struct crypt_mnt_ftr)) {
SLOGE("Cannot write real block device footer\n");
goto errout;
}
if (key) {
if (crypt_ftr->keysize != KEY_LEN_BYTES) {
SLOGE("Keysize of %d bits not supported for real block device %s\n",
crypt_ftr->keysize*8, fname);
goto errout;
}
if ( (cnt = write(fd, key, crypt_ftr->keysize)) != crypt_ftr->keysize) {
SLOGE("Cannot write key for real block device %s\n", fname);
goto errout;
}
}
if (salt) {
/* Compute the offset from the last write to the salt */
off = KEY_TO_SALT_PADDING;
if (! key)
off += crypt_ftr->keysize;
if (lseek64(fd, off, SEEK_CUR) == -1) {
SLOGE("Cannot seek to real block device salt \n");
goto errout;
}
if ( (cnt = write(fd, salt, SALT_LEN)) != SALT_LEN) {
SLOGE("Cannot write salt for real block device %s\n", fname);
goto errout;
}
}
fstat(fd, &statbuf);
/* If the keys are kept on a raw block device, do not try to truncate it. */
if (S_ISREG(statbuf.st_mode) && (key_loc[0] == '/')) {
if (ftruncate(fd, 0x4000)) {
SLOGE("Cannot set footer file size\n", fname);
goto errout;
}
}
/* Success! */
rc = 0;
errout:
close(fd);
return rc;
}
static int get_crypt_ftr_and_key(char *real_blk_name, struct crypt_mnt_ftr *crypt_ftr,
unsigned char *key, unsigned char *salt)
{
int fd;
unsigned int nr_sec, cnt;
off64_t off;
int rc = -1;
char key_loc[PROPERTY_VALUE_MAX];
char *fname;
struct stat statbuf;
fs_mgr_get_crypt_info(get_fstab_filename(), key_loc, 0, sizeof(key_loc));
if (!strcmp(key_loc, KEY_IN_FOOTER)) {
fname = real_blk_name;
if ( (fd = open(fname, O_RDONLY)) < 0) {
SLOGE("Cannot open real block device %s\n", fname);
return -1;
}
if ( (nr_sec = get_blkdev_size(fd)) == 0) {
SLOGE("Cannot get size of block device %s\n", fname);
goto errout;
}
/* If it's an encrypted Android partition, the last 16 Kbytes contain the
* encryption info footer and key, and plenty of bytes to spare for future
* growth.
*/
off = ((off64_t)nr_sec * 512) - CRYPT_FOOTER_OFFSET;
if (lseek64(fd, off, SEEK_SET) == -1) {
SLOGE("Cannot seek to real block device footer\n");
goto errout;
}
} else if (key_loc[0] == '/') {
fname = key_loc;
if ( (fd = open(fname, O_RDONLY)) < 0) {
SLOGE("Cannot open footer file %s\n", fname);
return -1;
}
/* Make sure it's 16 Kbytes in length */
fstat(fd, &statbuf);
if (S_ISREG(statbuf.st_mode) && (statbuf.st_size != 0x4000)) {
SLOGE("footer file %s is not the expected size!\n", fname);
goto errout;
}
} else {
SLOGE("Unexpected value for crypto key location\n");
return -1;;
}
if ( (cnt = read(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr))) != sizeof(struct crypt_mnt_ftr)) {
SLOGE("Cannot read real block device footer\n");
goto errout;
}
if (crypt_ftr->magic != CRYPT_MNT_MAGIC) {
SLOGE("Bad magic for real block device %s\n", fname);
goto errout;
}
if (crypt_ftr->major_version != 1) {
SLOGE("Cannot understand major version %d real block device footer\n",
crypt_ftr->major_version);
goto errout;
}
if (crypt_ftr->minor_version != 0) {
SLOGW("Warning: crypto footer minor version %d, expected 0, continuing...\n",
crypt_ftr->minor_version);
}
if (crypt_ftr->ftr_size > sizeof(struct crypt_mnt_ftr)) {
/* the footer size is bigger than we expected.
* Skip to it's stated end so we can read the key.
*/
if (lseek(fd, crypt_ftr->ftr_size - sizeof(struct crypt_mnt_ftr), SEEK_CUR) == -1) {
SLOGE("Cannot seek to start of key\n");
goto errout;
}
}
if (crypt_ftr->keysize != KEY_LEN_BYTES) {
SLOGE("Keysize of %d bits not supported for real block device %s\n",
crypt_ftr->keysize * 8, fname);
goto errout;
}
if ( (cnt = read(fd, key, crypt_ftr->keysize)) != crypt_ftr->keysize) {
SLOGE("Cannot read key for real block device %s\n", fname);
goto errout;
}
if (lseek64(fd, KEY_TO_SALT_PADDING, SEEK_CUR) == -1) {
SLOGE("Cannot seek to real block device salt\n");
goto errout;
}
if ( (cnt = read(fd, salt, SALT_LEN)) != SALT_LEN) {
SLOGE("Cannot read salt for real block device %s\n", fname);
goto errout;
}
/* Success! */
rc = 0;
errout:
close(fd);
return rc;
}
/* Convert a binary key of specified length into an ascii hex string equivalent,
* without the leading 0x and with null termination
*/
void convert_key_to_hex_ascii(unsigned char *master_key, unsigned int keysize,
char *master_key_ascii)
{
unsigned int i, a;
unsigned char nibble;
for (i=0, a=0; i<keysize; i++, a+=2) {
/* For each byte, write out two ascii hex digits */
nibble = (master_key[i] >> 4) & 0xf;
master_key_ascii[a] = nibble + (nibble > 9 ? 0x37 : 0x30);
nibble = master_key[i] & 0xf;
master_key_ascii[a+1] = nibble + (nibble > 9 ? 0x37 : 0x30);
}
/* Add the null termination */
master_key_ascii[a] = '\0';
}
static int create_crypto_blk_dev(struct crypt_mnt_ftr *crypt_ftr, unsigned char *master_key,
char *real_blk_name, char *crypto_blk_name, const char *name)
{
char buffer[DM_CRYPT_BUF_SIZE];
char master_key_ascii[129]; /* Large enough to hold 512 bit key and null */
char *crypt_params;
struct dm_ioctl *io;
struct dm_target_spec *tgt;
unsigned int minor;
int fd;
int i;
int retval = -1;
if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) {
SLOGE("Cannot open device-mapper\n");
goto errout;
}
io = (struct dm_ioctl *) buffer;
ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0);
if (ioctl(fd, DM_DEV_CREATE, io)) {
SLOGE("Cannot create dm-crypt device\n");
goto errout;
}
/* Get the device status, in particular, the name of it's device file */
ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0);
if (ioctl(fd, DM_DEV_STATUS, io)) {
SLOGE("Cannot retrieve dm-crypt device status\n");
goto errout;
}
minor = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
snprintf(crypto_blk_name, MAXPATHLEN, "/dev/block/dm-%u", minor);
/* Load the mapping table for this device */
tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
ioctl_init(io, 4096, name, 0);
io->target_count = 1;
tgt->status = 0;
tgt->sector_start = 0;
tgt->length = crypt_ftr->fs_size;
strcpy(tgt->target_type, "crypt");
crypt_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii);
sprintf(crypt_params, "%s %s 0 %s 0", crypt_ftr->crypto_type_name,
master_key_ascii, real_blk_name);
crypt_params += strlen(crypt_params) + 1;
crypt_params = (char *) (((unsigned long)crypt_params + 7) & ~8); /* Align to an 8 byte boundary */
tgt->next = crypt_params - buffer;
for (i = 0; i < TABLE_LOAD_RETRIES; i++) {
if (! ioctl(fd, DM_TABLE_LOAD, io)) {
break;
}
usleep(500000);
}
if (i == TABLE_LOAD_RETRIES) {
SLOGE("Cannot load dm-crypt mapping table.\n");
goto errout;
} else if (i) {
SLOGI("Took %d tries to load dmcrypt table.\n", i + 1);
}
/* Resume this device to activate it */
ioctl_init(io, 4096, name, 0);
if (ioctl(fd, DM_DEV_SUSPEND, io)) {
SLOGE("Cannot resume the dm-crypt device\n");
goto errout;
}
/* We made it here with no errors. Woot! */
retval = 0;
errout:
close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */
return retval;
}
static int delete_crypto_blk_dev(char *name)
{
int fd;
char buffer[DM_CRYPT_BUF_SIZE];
struct dm_ioctl *io;
int retval = -1;
if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) {
SLOGE("Cannot open device-mapper\n");
goto errout;
}
io = (struct dm_ioctl *) buffer;
ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0);
if (ioctl(fd, DM_DEV_REMOVE, io)) {
SLOGE("Cannot remove dm-crypt device\n");
goto errout;
}
/* We made it here with no errors. Woot! */
retval = 0;
errout:
close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */
return retval;
}
static void pbkdf2(char *passwd, unsigned char *salt, unsigned char *ikey)
{
/* Turn the password into a key and IV that can decrypt the master key */
PKCS5_PBKDF2_HMAC_SHA1(passwd, strlen(passwd), salt, SALT_LEN,
HASH_COUNT, KEY_LEN_BYTES+IV_LEN_BYTES, ikey);
}
static int encrypt_master_key(char *passwd, unsigned char *salt,
unsigned char *decrypted_master_key,
unsigned char *encrypted_master_key)
{
unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */
EVP_CIPHER_CTX e_ctx;
int encrypted_len, final_len;
/* Turn the password into a key and IV that can decrypt the master key */
pbkdf2(passwd, salt, ikey);
/* Initialize the decryption engine */
if (! EVP_EncryptInit(&e_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptInit failed\n");
return -1;
}
EVP_CIPHER_CTX_set_padding(&e_ctx, 0); /* Turn off padding as our data is block aligned */
/* Encrypt the master key */
if (! EVP_EncryptUpdate(&e_ctx, encrypted_master_key, &encrypted_len,
decrypted_master_key, KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptUpdate failed\n");
return -1;
}
if (! EVP_EncryptFinal(&e_ctx, encrypted_master_key + encrypted_len, &final_len)) {
SLOGE("EVP_EncryptFinal failed\n");
return -1;
}
if (encrypted_len + final_len != KEY_LEN_BYTES) {
SLOGE("EVP_Encryption length check failed with %d, %d bytes\n", encrypted_len, final_len);
return -1;
} else {
return 0;
}
}
static int decrypt_master_key(char *passwd, unsigned char *salt,
unsigned char *encrypted_master_key,
unsigned char *decrypted_master_key)
{
unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */
EVP_CIPHER_CTX d_ctx;
int decrypted_len, final_len;
/* Turn the password into a key and IV that can decrypt the master key */
pbkdf2(passwd, salt, ikey);
/* Initialize the decryption engine */
if (! EVP_DecryptInit(&d_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) {
return -1;
}
EVP_CIPHER_CTX_set_padding(&d_ctx, 0); /* Turn off padding as our data is block aligned */
/* Decrypt the master key */
if (! EVP_DecryptUpdate(&d_ctx, decrypted_master_key, &decrypted_len,
encrypted_master_key, KEY_LEN_BYTES)) {
return -1;
}
if (! EVP_DecryptFinal(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) {
return -1;
}
if (decrypted_len + final_len != KEY_LEN_BYTES) {
return -1;
} else {
return 0;
}
}
static int create_encrypted_random_key(char *passwd, unsigned char *master_key, unsigned char *salt)
{
int fd;
unsigned char key_buf[KEY_LEN_BYTES];
EVP_CIPHER_CTX e_ctx;
int encrypted_len, final_len;
/* Get some random bits for a key */
fd = open("/dev/urandom", O_RDONLY);
read(fd, key_buf, sizeof(key_buf));
read(fd, salt, SALT_LEN);
close(fd);
/* Now encrypt it with the password */
return encrypt_master_key(passwd, salt, key_buf, master_key);
}
static int wait_and_unmount(char *mountpoint)
{
int i, rc;
#define WAIT_UNMOUNT_COUNT 20
/* Now umount the tmpfs filesystem */
for (i=0; i<WAIT_UNMOUNT_COUNT; i++) {
if (umount(mountpoint)) {
if (errno == EINVAL) {
/* EINVAL is returned if the directory is not a mountpoint,
* i.e. there is no filesystem mounted there. So just get out.
*/
break;
}
sleep(1);
i++;
} else {
break;
}
}
if (i < WAIT_UNMOUNT_COUNT) {
SLOGD("unmounting %s succeeded\n", mountpoint);
rc = 0;
} else {
SLOGE("unmounting %s failed\n", mountpoint);
rc = -1;
}
return rc;
}
#define DATA_PREP_TIMEOUT 100
static int prep_data_fs(void)
{
int i;
/* Do the prep of the /data filesystem */
property_set("vold.post_fs_data_done", "0");
property_set("vold.decrypt", "trigger_post_fs_data");
SLOGD("Just triggered post_fs_data\n");
/* Wait a max of 25 seconds, hopefully it takes much less */
for (i=0; i<DATA_PREP_TIMEOUT; i++) {
char p[PROPERTY_VALUE_MAX];
property_get("vold.post_fs_data_done", p, "0");
if (*p == '1') {
break;
} else {
usleep(250000);
}
}
if (i == DATA_PREP_TIMEOUT) {
/* Ugh, we failed to prep /data in time. Bail. */
return -1;
} else {
SLOGD("post_fs_data done\n");
return 0;
}
}
int cryptfs_restart(void)
{
char fs_type[32];
char real_blkdev[MAXPATHLEN];
char crypto_blkdev[MAXPATHLEN];
char fs_options[256];
unsigned long mnt_flags;
struct stat statbuf;
int rc = -1, i;
static int restart_successful = 0;
/* Validate that it's OK to call this routine */
if (! master_key_saved) {
SLOGE("Encrypted filesystem not validated, aborting");
return -1;
}
if (restart_successful) {
SLOGE("System already restarted with encrypted disk, aborting");
return -1;
}
/* Here is where we shut down the framework. The init scripts
* start all services in one of three classes: core, main or late_start.
* On boot, we start core and main. Now, we stop main, but not core,
* as core includes vold and a few other really important things that
* we need to keep running. Once main has stopped, we should be able
* to umount the tmpfs /data, then mount the encrypted /data.
* We then restart the class main, and also the class late_start.
* At the moment, I've only put a few things in late_start that I know
* are not needed to bring up the framework, and that also cause problems
* with unmounting the tmpfs /data, but I hope to add add more services
* to the late_start class as we optimize this to decrease the delay
* till the user is asked for the password to the filesystem.
*/
/* The init files are setup to stop the class main when vold.decrypt is
* set to trigger_reset_main.
*/
property_set("vold.decrypt", "trigger_reset_main");
SLOGD("Just asked init to shut down class main\n");
/* Give everything a chance to shutdown */
sleep(1);
/* Now that the framework is shutdown, we should be able to umount()
* the tmpfs filesystem, and mount the real one.
*/
property_get("ro.crypto.fs_crypto_blkdev", crypto_blkdev, "");
if (strlen(crypto_blkdev) == 0) {
SLOGE("fs_crypto_blkdev not set\n");
return -1;
}
if (! (rc = wait_and_unmount(DATA_MNT_POINT)) ) {
/* If that succeeded, then mount the decrypted filesystem */
fs_mgr_do_mount(get_fstab_filename(), DATA_MNT_POINT, crypto_blkdev, 0);
property_set("vold.decrypt", "trigger_load_persist_props");
/* Create necessary paths on /data */
if (prep_data_fs()) {
return -1;
}
/* startup service classes main and late_start */
property_set("vold.decrypt", "trigger_restart_framework");
SLOGD("Just triggered restart_framework\n");
/* Give it a few moments to get started */
sleep(1);
}
if (rc == 0) {
restart_successful = 1;
}
return rc;
}
static int do_crypto_complete(char *mount_point)
{
struct crypt_mnt_ftr crypt_ftr;
unsigned char encrypted_master_key[32];
unsigned char salt[SALT_LEN];
char real_blkdev[MAXPATHLEN];
char encrypted_state[PROPERTY_VALUE_MAX];
char key_loc[PROPERTY_VALUE_MAX];
property_get("ro.crypto.state", encrypted_state, "");
if (strcmp(encrypted_state, "encrypted") ) {
SLOGE("not running with encryption, aborting");
return 1;
}
fs_mgr_get_crypt_info(get_fstab_filename(), 0, real_blkdev, sizeof(real_blkdev));
if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt)) {
fs_mgr_get_crypt_info(get_fstab_filename(), key_loc, 0, sizeof(key_loc));
/*
* Only report this error if key_loc is a file and it exists.
* If the device was never encrypted, and /data is not mountable for
* some reason, returning 1 should prevent the UI from presenting the
* a "enter password" screen, or worse, a "press button to wipe the
* device" screen.
*/
if ((key_loc[0] == '/') && (access("key_loc", F_OK) == -1)) {
SLOGE("master key file does not exist, aborting");
return 1;
} else {
SLOGE("Error getting crypt footer and key\n");
return -1;
}
}
if (crypt_ftr.flags & CRYPT_ENCRYPTION_IN_PROGRESS) {
SLOGE("Encryption process didn't finish successfully\n");
return -2; /* -2 is the clue to the UI that there is no usable data on the disk,
* and give the user an option to wipe the disk */
}
/* We passed the test! We shall diminish, and return to the west */
return 0;
}
static int test_mount_encrypted_fs(char *passwd, char *mount_point, char *label)
{
struct crypt_mnt_ftr crypt_ftr;
/* Allocate enough space for a 256 bit key, but we may use less */
unsigned char encrypted_master_key[32], decrypted_master_key[32];
unsigned char salt[SALT_LEN];
char crypto_blkdev[MAXPATHLEN];
char real_blkdev[MAXPATHLEN];
char tmp_mount_point[64];
unsigned int orig_failed_decrypt_count;
char encrypted_state[PROPERTY_VALUE_MAX];
int rc;
property_get("ro.crypto.state", encrypted_state, "");
if ( master_key_saved || strcmp(encrypted_state, "encrypted") ) {
SLOGE("encrypted fs already validated or not running with encryption, aborting");
return -1;
}
fs_mgr_get_crypt_info(get_fstab_filename(), 0, real_blkdev, sizeof(real_blkdev));
if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt)) {
SLOGE("Error getting crypt footer and key\n");
return -1;
}
SLOGD("crypt_ftr->fs_size = %lld\n", crypt_ftr.fs_size);
orig_failed_decrypt_count = crypt_ftr.failed_decrypt_count;
if (! (crypt_ftr.flags & CRYPT_MNT_KEY_UNENCRYPTED) ) {
decrypt_master_key(passwd, salt, encrypted_master_key, decrypted_master_key);
}
if (create_crypto_blk_dev(&crypt_ftr, decrypted_master_key,
real_blkdev, crypto_blkdev, label)) {
SLOGE("Error creating decrypted block device\n");
return -1;
}
/* If init detects an encrypted filesystme, it writes a file for each such
* encrypted fs into the tmpfs /data filesystem, and then the framework finds those
* files and passes that data to me */
/* Create a tmp mount point to try mounting the decryptd fs
* Since we're here, the mount_point should be a tmpfs filesystem, so make
* a directory in it to test mount the decrypted filesystem.
*/
sprintf(tmp_mount_point, "%s/tmp_mnt", mount_point);
mkdir(tmp_mount_point, 0755);
if (fs_mgr_do_mount(get_fstab_filename(), DATA_MNT_POINT, crypto_blkdev, tmp_mount_point)) {
SLOGE("Error temp mounting decrypted block device\n");
delete_crypto_blk_dev(label);
crypt_ftr.failed_decrypt_count++;
} else {
/* Success, so just umount and we'll mount it properly when we restart
* the framework.
*/
umount(tmp_mount_point);
crypt_ftr.failed_decrypt_count = 0;
}
if (orig_failed_decrypt_count != crypt_ftr.failed_decrypt_count) {
put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, 0, 0);
}
if (crypt_ftr.failed_decrypt_count) {
/* We failed to mount the device, so return an error */
rc = crypt_ftr.failed_decrypt_count;
} else {
/* Woot! Success! Save the name of the crypto block device
* so we can mount it when restarting the framework.
*/
property_set("ro.crypto.fs_crypto_blkdev", crypto_blkdev);
/* Also save a the master key so we can reencrypted the key
* the key when we want to change the password on it.
*/
memcpy(saved_master_key, decrypted_master_key, KEY_LEN_BYTES);
saved_data_blkdev = strdup(real_blkdev);
saved_mount_point = strdup(mount_point);
master_key_saved = 1;
rc = 0;
}
return rc;
}
/* Called by vold when it wants to undo the crypto mapping of a volume it
* manages. This is usually in response to a factory reset, when we want
* to undo the crypto mapping so the volume is formatted in the clear.
*/
int cryptfs_revert_volume(const char *label)
{
return delete_crypto_blk_dev((char *)label);
}
/*
* Called by vold when it's asked to mount an encrypted, nonremovable volume.
* Setup a dm-crypt mapping, use the saved master key from
* setting up the /data mapping, and return the new device path.
*/
int cryptfs_setup_volume(const char *label, int major, int minor,
char *crypto_sys_path, unsigned int max_path,
int *new_major, int *new_minor)
{
char real_blkdev[MAXPATHLEN], crypto_blkdev[MAXPATHLEN];
struct crypt_mnt_ftr sd_crypt_ftr;
unsigned char key[32], salt[32];
struct stat statbuf;
int nr_sec, fd;
sprintf(real_blkdev, "/dev/block/vold/%d:%d", major, minor);
/* Just want the footer, but gotta get it all */
get_crypt_ftr_and_key(saved_data_blkdev, &sd_crypt_ftr, key, salt);
/* Update the fs_size field to be the size of the volume */
fd = open(real_blkdev, O_RDONLY);
nr_sec = get_blkdev_size(fd);
close(fd);
if (nr_sec == 0) {
SLOGE("Cannot get size of volume %s\n", real_blkdev);
return -1;
}
sd_crypt_ftr.fs_size = nr_sec;
create_crypto_blk_dev(&sd_crypt_ftr, saved_master_key, real_blkdev,
crypto_blkdev, label);
stat(crypto_blkdev, &statbuf);
*new_major = MAJOR(statbuf.st_rdev);
*new_minor = MINOR(statbuf.st_rdev);
/* Create path to sys entry for this block device */
snprintf(crypto_sys_path, max_path, "/devices/virtual/block/%s", strrchr(crypto_blkdev, '/')+1);
return 0;
}
int cryptfs_crypto_complete(void)
{
return do_crypto_complete("/data");
}
int cryptfs_check_passwd(char *passwd)
{
int rc = -1;
rc = test_mount_encrypted_fs(passwd, DATA_MNT_POINT, "userdata");
return rc;
}
int cryptfs_verify_passwd(char *passwd)
{
struct crypt_mnt_ftr crypt_ftr;
/* Allocate enough space for a 256 bit key, but we may use less */
unsigned char encrypted_master_key[32], decrypted_master_key[32];
unsigned char salt[SALT_LEN];
char real_blkdev[MAXPATHLEN];
char encrypted_state[PROPERTY_VALUE_MAX];
int rc;
property_get("ro.crypto.state", encrypted_state, "");
if (strcmp(encrypted_state, "encrypted") ) {
SLOGE("device not encrypted, aborting");
return -2;
}
if (!master_key_saved) {
SLOGE("encrypted fs not yet mounted, aborting");
return -1;
}
if (!saved_mount_point) {
SLOGE("encrypted fs failed to save mount point, aborting");
return -1;
}
fs_mgr_get_crypt_info(get_fstab_filename(), 0, real_blkdev, sizeof(real_blkdev));
if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt)) {
SLOGE("Error getting crypt footer and key\n");
return -1;
}
if (crypt_ftr.flags & CRYPT_MNT_KEY_UNENCRYPTED) {
/* If the device has no password, then just say the password is valid */
rc = 0;
} else {
decrypt_master_key(passwd, salt, encrypted_master_key, decrypted_master_key);
if (!memcmp(decrypted_master_key, saved_master_key, crypt_ftr.keysize)) {
/* They match, the password is correct */
rc = 0;
} else {
/* If incorrect, sleep for a bit to prevent dictionary attacks */
sleep(1);
rc = 1;
}
}
return rc;
}
/* Initialize a crypt_mnt_ftr structure. The keysize is
* defaulted to 16 bytes, and the filesystem size to 0.
* Presumably, at a minimum, the caller will update the
* filesystem size and crypto_type_name after calling this function.
*/
static void cryptfs_init_crypt_mnt_ftr(struct crypt_mnt_ftr *ftr)
{
ftr->magic = CRYPT_MNT_MAGIC;
ftr->major_version = 1;
ftr->minor_version = 0;
ftr->ftr_size = sizeof(struct crypt_mnt_ftr);
ftr->flags = 0;
ftr->keysize = KEY_LEN_BYTES;
ftr->spare1 = 0;
ftr->fs_size = 0;
ftr->failed_decrypt_count = 0;
ftr->crypto_type_name[0] = '\0';
}
static int cryptfs_enable_wipe(char *crypto_blkdev, off64_t size, int type)
{
char cmdline[256];
int rc = -1;
if (type == EXT4_FS) {
snprintf(cmdline, sizeof(cmdline), "/system/bin/make_ext4fs -a /data -l %lld %s",
size * 512, crypto_blkdev);
SLOGI("Making empty filesystem with command %s\n", cmdline);
} else if (type== FAT_FS) {
snprintf(cmdline, sizeof(cmdline), "/system/bin/newfs_msdos -F 32 -O android -c 8 -s %lld %s",
size, crypto_blkdev);
SLOGI("Making empty filesystem with command %s\n", cmdline);
} else {
SLOGE("cryptfs_enable_wipe(): unknown filesystem type %d\n", type);
return -1;
}
if (system(cmdline)) {
SLOGE("Error creating empty filesystem on %s\n", crypto_blkdev);
} else {
SLOGD("Successfully created empty filesystem on %s\n", crypto_blkdev);
rc = 0;
}
return rc;
}
static inline int unix_read(int fd, void* buff, int len)
{
int ret;
do { ret = read(fd, buff, len); } while (ret < 0 && errno == EINTR);
return ret;
}
static inline int unix_write(int fd, const void* buff, int len)
{
int ret;
do { ret = write(fd, buff, len); } while (ret < 0 && errno == EINTR);
return ret;
}
#define CRYPT_INPLACE_BUFSIZE 4096
#define CRYPT_SECTORS_PER_BUFSIZE (CRYPT_INPLACE_BUFSIZE / 512)
static int cryptfs_enable_inplace(char *crypto_blkdev, char *real_blkdev, off64_t size,
off64_t *size_already_done, off64_t tot_size)
{
int realfd, cryptofd;
char *buf[CRYPT_INPLACE_BUFSIZE];
int rc = -1;
off64_t numblocks, i, remainder;
off64_t one_pct, cur_pct, new_pct;
off64_t blocks_already_done, tot_numblocks;
if ( (realfd = open(real_blkdev, O_RDONLY)) < 0) {
SLOGE("Error opening real_blkdev %s for inplace encrypt\n", real_blkdev);
return -1;
}
if ( (cryptofd = open(crypto_blkdev, O_WRONLY)) < 0) {
SLOGE("Error opening crypto_blkdev %s for inplace encrypt\n", crypto_blkdev);
close(realfd);
return -1;
}
/* This is pretty much a simple loop of reading 4K, and writing 4K.
* The size passed in is the number of 512 byte sectors in the filesystem.
* So compute the number of whole 4K blocks we should read/write,
* and the remainder.
*/
numblocks = size / CRYPT_SECTORS_PER_BUFSIZE;
remainder = size % CRYPT_SECTORS_PER_BUFSIZE;
tot_numblocks = tot_size / CRYPT_SECTORS_PER_BUFSIZE;
blocks_already_done = *size_already_done / CRYPT_SECTORS_PER_BUFSIZE;
SLOGE("Encrypting filesystem in place...");
one_pct = tot_numblocks / 100;
cur_pct = 0;
/* process the majority of the filesystem in blocks */
for (i=0; i<numblocks; i++) {
new_pct = (i + blocks_already_done) / one_pct;
if (new_pct > cur_pct) {
char buf[8];
cur_pct = new_pct;
snprintf(buf, sizeof(buf), "%lld", cur_pct);
property_set("vold.encrypt_progress", buf);
}
if (unix_read(realfd, buf, CRYPT_INPLACE_BUFSIZE) <= 0) {
SLOGE("Error reading real_blkdev %s for inplace encrypt\n", crypto_blkdev);
goto errout;
}
if (unix_write(cryptofd, buf, CRYPT_INPLACE_BUFSIZE) <= 0) {
SLOGE("Error writing crypto_blkdev %s for inplace encrypt\n", crypto_blkdev);
goto errout;
}
}
/* Do any remaining sectors */
for (i=0; i<remainder; i++) {
if (unix_read(realfd, buf, 512) <= 0) {
SLOGE("Error reading rival sectors from real_blkdev %s for inplace encrypt\n", crypto_blkdev);
goto errout;
}
if (unix_write(cryptofd, buf, 512) <= 0) {
SLOGE("Error writing final sectors to crypto_blkdev %s for inplace encrypt\n", crypto_blkdev);
goto errout;
}
}
*size_already_done += size;
rc = 0;
errout:
close(realfd);
close(cryptofd);
return rc;
}
#define CRYPTO_ENABLE_WIPE 1
#define CRYPTO_ENABLE_INPLACE 2
#define FRAMEWORK_BOOT_WAIT 60
static inline int should_encrypt(struct volume_info *volume)
{
return (volume->flags & (VOL_ENCRYPTABLE | VOL_NONREMOVABLE)) ==
(VOL_ENCRYPTABLE | VOL_NONREMOVABLE);
}
int cryptfs_enable(char *howarg, char *passwd)
{
int how = 0;
char crypto_blkdev[MAXPATHLEN], real_blkdev[MAXPATHLEN], sd_crypto_blkdev[MAXPATHLEN];
unsigned long nr_sec;
unsigned char master_key[KEY_LEN_BYTES], decrypted_master_key[KEY_LEN_BYTES];
unsigned char salt[SALT_LEN];
int rc=-1, fd, i, ret;
struct crypt_mnt_ftr crypt_ftr, sd_crypt_ftr;;
char tmpfs_options[PROPERTY_VALUE_MAX];
char encrypted_state[PROPERTY_VALUE_MAX];
char lockid[32] = { 0 };
char key_loc[PROPERTY_VALUE_MAX];
char fuse_sdcard[PROPERTY_VALUE_MAX];
char *sd_mnt_point;
char sd_blk_dev[256] = { 0 };
int num_vols;
struct volume_info *vol_list = 0;
off64_t cur_encryption_done=0, tot_encryption_size=0;
property_get("ro.crypto.state", encrypted_state, "");
if (strcmp(encrypted_state, "unencrypted")) {
SLOGE("Device is already running encrypted, aborting");
goto error_unencrypted;
}
fs_mgr_get_crypt_info(get_fstab_filename(), key_loc, 0, sizeof(key_loc));
if (!strcmp(howarg, "wipe")) {
how = CRYPTO_ENABLE_WIPE;
} else if (! strcmp(howarg, "inplace")) {
how = CRYPTO_ENABLE_INPLACE;
} else {
/* Shouldn't happen, as CommandListener vets the args */
goto error_unencrypted;
}
fs_mgr_get_crypt_info(get_fstab_filename(), 0, real_blkdev, sizeof(real_blkdev));
/* Get the size of the real block device */
fd = open(real_blkdev, O_RDONLY);
if ( (nr_sec = get_blkdev_size(fd)) == 0) {
SLOGE("Cannot get size of block device %s\n", real_blkdev);
goto error_unencrypted;
}
close(fd);
/* If doing inplace encryption, make sure the orig fs doesn't include the crypto footer */
if ((how == CRYPTO_ENABLE_INPLACE) && (!strcmp(key_loc, KEY_IN_FOOTER))) {
unsigned int fs_size_sec, max_fs_size_sec;
fs_size_sec = get_fs_size(real_blkdev);
max_fs_size_sec = nr_sec - (CRYPT_FOOTER_OFFSET / 512);
if (fs_size_sec > max_fs_size_sec) {
SLOGE("Orig filesystem overlaps crypto footer region. Cannot encrypt in place.");
goto error_unencrypted;
}
}
/* Get a wakelock as this may take a while, and we don't want the
* device to sleep on us. We'll grab a partial wakelock, and if the UI
* wants to keep the screen on, it can grab a full wakelock.
*/
snprintf(lockid, sizeof(lockid), "enablecrypto%d", (int) getpid());
acquire_wake_lock(PARTIAL_WAKE_LOCK, lockid);
/* Get the sdcard mount point */
sd_mnt_point = getenv("EMULATED_STORAGE_SOURCE");
if (!sd_mnt_point) {
sd_mnt_point = getenv("EXTERNAL_STORAGE");
}
if (!sd_mnt_point) {
sd_mnt_point = "/mnt/sdcard";
}
num_vols=vold_getNumDirectVolumes();
vol_list = malloc(sizeof(struct volume_info) * num_vols);
vold_getDirectVolumeList(vol_list);
for (i=0; i<num_vols; i++) {
if (should_encrypt(&vol_list[i])) {
fd = open(vol_list[i].blk_dev, O_RDONLY);
if ( (vol_list[i].size = get_blkdev_size(fd)) == 0) {
SLOGE("Cannot get size of block device %s\n", vol_list[i].blk_dev);
goto error_unencrypted;
}
close(fd);
ret=vold_disableVol(vol_list[i].label);
if ((ret < 0) && (ret != UNMOUNT_NOT_MOUNTED_ERR)) {
/* -2 is returned when the device exists but is not currently mounted.
* ignore the error and continue. */
SLOGE("Failed to unmount volume %s\n", vol_list[i].label);
goto error_unencrypted;
}
}
}
/* The init files are setup to stop the class main and late start when
* vold sets trigger_shutdown_framework.
*/
property_set("vold.decrypt", "trigger_shutdown_framework");
SLOGD("Just asked init to shut down class main\n");
if (vold_unmountAllAsecs()) {
/* Just report the error. If any are left mounted,
* umounting /data below will fail and handle the error.
*/
SLOGE("Error unmounting internal asecs");
}
property_get("ro.crypto.fuse_sdcard", fuse_sdcard, "");
if (!strcmp(fuse_sdcard, "true")) {
/* This is a device using the fuse layer to emulate the sdcard semantics
* on top of the userdata partition. vold does not manage it, it is managed
* by the sdcard service. The sdcard service was killed by the property trigger
* above, so just unmount it now. We must do this _AFTER_ killing the framework,
* unlike the case for vold managed devices above.
*/
if (wait_and_unmount(sd_mnt_point)) {
goto error_shutting_down;
}
}
/* Now unmount the /data partition. */
if (wait_and_unmount(DATA_MNT_POINT)) {
goto error_shutting_down;
}
/* Do extra work for a better UX when doing the long inplace encryption */
if (how == CRYPTO_ENABLE_INPLACE) {
/* Now that /data is unmounted, we need to mount a tmpfs
* /data, set a property saying we're doing inplace encryption,
* and restart the framework.
*/
if (fs_mgr_do_tmpfs_mount(DATA_MNT_POINT)) {
goto error_shutting_down;
}
/* Tells the framework that inplace encryption is starting */
property_set("vold.encrypt_progress", "0");
/* restart the framework. */
/* Create necessary paths on /data */
if (prep_data_fs()) {
goto error_shutting_down;
}
/* startup service classes main and late_start */
property_set("vold.decrypt", "trigger_restart_min_framework");
SLOGD("Just triggered restart_min_framework\n");
/* OK, the framework is restarted and will soon be showing a
* progress bar. Time to setup an encrypted mapping, and
* either write a new filesystem, or encrypt in place updating
* the progress bar as we work.
*/
}
/* Start the actual work of making an encrypted filesystem */
/* Initialize a crypt_mnt_ftr for the partition */
cryptfs_init_crypt_mnt_ftr(&crypt_ftr);
if (!strcmp(key_loc, KEY_IN_FOOTER)) {
crypt_ftr.fs_size = nr_sec - (CRYPT_FOOTER_OFFSET / 512);
} else {
crypt_ftr.fs_size = nr_sec;
}
crypt_ftr.flags |= CRYPT_ENCRYPTION_IN_PROGRESS;
strcpy((char *)crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256");
/* Make an encrypted master key */
if (create_encrypted_random_key(passwd, master_key, salt)) {
SLOGE("Cannot create encrypted master key\n");
goto error_unencrypted;
}
/* Write the key to the end of the partition */
put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, master_key, salt);
decrypt_master_key(passwd, salt, master_key, decrypted_master_key);
create_crypto_blk_dev(&crypt_ftr, decrypted_master_key, real_blkdev, crypto_blkdev,
"userdata");
/* The size of the userdata partition, and add in the vold volumes below */
tot_encryption_size = crypt_ftr.fs_size;
/* setup crypto mapping for all encryptable volumes handled by vold */
for (i=0; i<num_vols; i++) {
if (should_encrypt(&vol_list[i])) {
vol_list[i].crypt_ftr = crypt_ftr; /* gotta love struct assign */
vol_list[i].crypt_ftr.fs_size = vol_list[i].size;
create_crypto_blk_dev(&vol_list[i].crypt_ftr, decrypted_master_key,
vol_list[i].blk_dev, vol_list[i].crypto_blkdev,
vol_list[i].label);
tot_encryption_size += vol_list[i].size;
}
}
if (how == CRYPTO_ENABLE_WIPE) {
rc = cryptfs_enable_wipe(crypto_blkdev, crypt_ftr.fs_size, EXT4_FS);
/* Encrypt all encryptable volumes handled by vold */
if (!rc) {
for (i=0; i<num_vols; i++) {
if (should_encrypt(&vol_list[i])) {
rc = cryptfs_enable_wipe(vol_list[i].crypto_blkdev,
vol_list[i].crypt_ftr.fs_size, FAT_FS);
}
}
}
} else if (how == CRYPTO_ENABLE_INPLACE) {
rc = cryptfs_enable_inplace(crypto_blkdev, real_blkdev, crypt_ftr.fs_size,
&cur_encryption_done, tot_encryption_size);
/* Encrypt all encryptable volumes handled by vold */
if (!rc) {
for (i=0; i<num_vols; i++) {
if (should_encrypt(&vol_list[i])) {
rc = cryptfs_enable_inplace(vol_list[i].crypto_blkdev,
vol_list[i].blk_dev,
vol_list[i].crypt_ftr.fs_size,
&cur_encryption_done, tot_encryption_size);
}
}
}
if (!rc) {
/* The inplace routine never actually sets the progress to 100%
* due to the round down nature of integer division, so set it here */
property_set("vold.encrypt_progress", "100");
}
} else {
/* Shouldn't happen */
SLOGE("cryptfs_enable: internal error, unknown option\n");
goto error_unencrypted;
}
/* Undo the dm-crypt mapping whether we succeed or not */
delete_crypto_blk_dev("userdata");
for (i=0; i<num_vols; i++) {
if (should_encrypt(&vol_list[i])) {
delete_crypto_blk_dev(vol_list[i].label);
}
}
free(vol_list);
if (! rc) {
/* Success */
/* Clear the encryption in progres flag in the footer */
crypt_ftr.flags &= ~CRYPT_ENCRYPTION_IN_PROGRESS;
put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, 0, 0);
sleep(2); /* Give the UI a chance to show 100% progress */
android_reboot(ANDROID_RB_RESTART, 0, 0);
} else {
char value[PROPERTY_VALUE_MAX];
property_get("ro.vold.wipe_on_crypt_fail", value, "0");
if (!strcmp(value, "1")) {
/* wipe data if encryption failed */
SLOGE("encryption failed - rebooting into recovery to wipe data\n");
mkdir("/cache/recovery", 0700);
int fd = open("/cache/recovery/command", O_RDWR|O_CREAT|O_TRUNC, 0600);
if (fd >= 0) {
write(fd, "--wipe_data", strlen("--wipe_data") + 1);
close(fd);
} else {
SLOGE("could not open /cache/recovery/command\n");
}
android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
} else {
/* set property to trigger dialog */
property_set("vold.encrypt_progress", "error_partially_encrypted");
release_wake_lock(lockid);
}
return -1;
}
/* hrm, the encrypt step claims success, but the reboot failed.
* This should not happen.
* Set the property and return. Hope the framework can deal with it.
*/
property_set("vold.encrypt_progress", "error_reboot_failed");
release_wake_lock(lockid);
return rc;
error_unencrypted:
free(vol_list);
property_set("vold.encrypt_progress", "error_not_encrypted");
if (lockid[0]) {
release_wake_lock(lockid);
}
return -1;
error_shutting_down:
/* we failed, and have not encrypted anthing, so the users's data is still intact,
* but the framework is stopped and not restarted to show the error, so it's up to
* vold to restart the system.
*/
SLOGE("Error enabling encryption after framework is shutdown, no data changed, restarting system");
android_reboot(ANDROID_RB_RESTART, 0, 0);
/* shouldn't get here */
property_set("vold.encrypt_progress", "error_shutting_down");
free(vol_list);
if (lockid[0]) {
release_wake_lock(lockid);
}
return -1;
}
int cryptfs_changepw(char *newpw)
{
struct crypt_mnt_ftr crypt_ftr;
unsigned char encrypted_master_key[KEY_LEN_BYTES], decrypted_master_key[KEY_LEN_BYTES];
unsigned char salt[SALT_LEN];
char real_blkdev[MAXPATHLEN];
/* This is only allowed after we've successfully decrypted the master key */
if (! master_key_saved) {
SLOGE("Key not saved, aborting");
return -1;
}
fs_mgr_get_crypt_info(get_fstab_filename(), 0, real_blkdev, sizeof(real_blkdev));
if (strlen(real_blkdev) == 0) {
SLOGE("Can't find real blkdev");
return -1;
}
/* get key */
if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt)) {
SLOGE("Error getting crypt footer and key");
return -1;
}
encrypt_master_key(newpw, salt, saved_master_key, encrypted_master_key);
/* save the key */
put_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt);
return 0;
}
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