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cryptfs.c
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cryptfs.c
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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;
extern struct fstab *fstab;
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;
}
/* 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(fstab, 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(fstab, 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 load_crypto_mapping_table(struct crypt_mnt_ftr *crypt_ftr, unsigned char *master_key,
char *real_blk_name, const char *name, int fd,
char *extra_params)
{
char buffer[DM_CRYPT_BUF_SIZE];
struct dm_ioctl *io;
struct dm_target_spec *tgt;
char *crypt_params;
char master_key_ascii[129]; /* Large enough to hold 512 bit key and null */
int i;
io = (struct dm_ioctl *) buffer;
/* Load the mapping table for this device */
tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
ioctl_init(io, DM_CRYPT_BUF_SIZE, 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 %s", crypt_ftr->crypto_type_name,
master_key_ascii, real_blk_name, extra_params);
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) {
/* We failed to load the table, return an error */
return -1;
} else {
return i + 1;
}
}
static int get_dm_crypt_version(int fd, const char *name, int *version)
{
char buffer[DM_CRYPT_BUF_SIZE];
struct dm_ioctl *io;
struct dm_target_versions *v;
int i;
io = (struct dm_ioctl *) buffer;
ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0);
if (ioctl(fd, DM_LIST_VERSIONS, io)) {
return -1;
}
/* Iterate over the returned versions, looking for name of "crypt".
* When found, get and return the version.
*/
v = (struct dm_target_versions *) &buffer[sizeof(struct dm_ioctl)];
while (v->next) {
if (! strcmp(v->name, "crypt")) {
/* We found the crypt driver, return the version, and get out */
version[0] = v->version[0];
version[1] = v->version[1];
version[2] = v->version[2];
return 0;
}
v = (struct dm_target_versions *)(((char *)v) + v->next);
}
return -1;
}
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;
int version[3];
char *extra_params;
int load_count;
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);
extra_params = "";
if (! get_dm_crypt_version(fd, name, version)) {
/* Support for allow_discards was added in version 1.11.0 */
if ((version[0] >= 2) ||
((version[0] == 1) && (version[1] >= 11))) {
extra_params = "1 allow_discards";
SLOGI("Enabling support for allow_discards in dmcrypt.\n");
}
}
load_count = load_crypto_mapping_table(crypt_ftr, master_key, real_blk_name, name,
fd, extra_params);
if (load_count < 0) {
SLOGE("Cannot load dm-crypt mapping table.\n");
goto errout;
} else if (load_count > 1) {
SLOGI("Took %d tries to load dmcrypt table.\n", load_count);
}
/* Resume this device to activate it */
ioctl_init(io, DM_CRYPT_BUF_SIZE, 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 200
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 50 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. */
SLOGE("post_fs_data timed out!\n");
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");
/* Ugh, shutting down the framework is not synchronous, so until it
* can be fixed, this horrible hack will wait a moment for it all to
* shut down before proceeding. Without it, some devices cannot
* restart the graphics services.
*/
sleep(2);
/* 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(fstab, 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(fstab, 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(fstab, 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(fstab, 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(fstab, 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, "");