blob: 193339ec96c2fb64aefe97b9df6601adba454e24 [file] [log] [blame]
/*
* 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 "cryptfs.h"
#define LOG_TAG "Cryptfs"
#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
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
#define KEY_LEN_BYTES_SAMSUNG (sizeof(edk_t))
#endif
#define KEY_LEN_BYTES 16
#define IV_LEN_BYTES 16
#define KEY_LOC_PROP "ro.crypto.keyfile.userdata"
#define KEY_IN_FOOTER "footer"
#define EXT4_FS 1
#define FAT_FS 2
#ifndef EXPAND
#define STRINGIFY(x) #x
#define EXPAND(x) STRINGIFY(x)
#endif
char *me = "cryptfs";
static char *saved_data_blkdev;
static char *saved_mount_point;
static int master_key_saved = 0;
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
static int using_samsung_encryption = 0;
//static edk_t saved_master_key;
static unsigned char saved_master_key[KEY_LEN_BYTES_SAMSUNG];
edk_payload_t edk_payload;
#else
static unsigned char saved_master_key[KEY_LEN_BYTES];
#endif
int cryptfs_setup_volume(const char *label, const char *real_blkdev, char *crypto_blkdev);
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_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)
{
// we don't need to update it...
return 0;
}
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;
property_get(KEY_LOC_PROP, key_loc, KEY_IN_FOOTER);
if (!strcmp(key_loc, KEY_IN_FOOTER)) {
fname = real_blk_name;
if ( (fd = open(fname, O_RDONLY)) < 0) {
printf("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) {
printf("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) {
printf("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
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
&& statbuf.st_size != 0x8000
#endif
)) {
printf("footer file %s is not the expected size!\n", fname);
goto errout;
}
} else {
printf("Unexpected value for" KEY_LOC_PROP "\n");
return -1;;
}
if ( (cnt = read(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr))) != sizeof(struct crypt_mnt_ftr)) {
printf("Cannot read real block device footer\n");
goto errout;
}
if (crypt_ftr->magic != CRYPT_MNT_MAGIC) {
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
if (crypt_ftr->magic != CRYPT_MNT_MAGIC_SAMSUNG) {
printf("Bad magic for real block device %s\n", fname);
goto errout;
} else {
printf("Using Samsung encryption.\n");
using_samsung_encryption = 1;
if ( (cnt = read(fd, &edk_payload, sizeof(edk_payload_t))) != sizeof(edk_payload_t)) {
printf("Cannot read EDK payload from real block device footer\n");
goto errout;
}
if (lseek64(fd, sizeof(__le32), SEEK_CUR) == -1) {
printf("Cannot seek past unknown data from real block device footer\n");
goto errout;
}
memcpy(key, &edk_payload, sizeof(edk_payload_t));
}
#else
printf("Bad magic for real block device %s\n", fname);
goto errout;
#endif
}
if (crypt_ftr->major_version != 1) {
printf("Cannot understand major version %d real block device footer\n",
crypt_ftr->major_version);
goto errout;
}
if (crypt_ftr->minor_version != 0) {
printf("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 (lseek64(fd, crypt_ftr->ftr_size - sizeof(struct crypt_mnt_ftr), SEEK_CUR) == -1) {
printf("Cannot seek to start of key\n");
goto errout;
}
}
if (crypt_ftr->keysize > sizeof(saved_master_key)) {
printf("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) {
printf("Cannot read key for real block device %s\n", fname);
goto errout;
}
if (lseek64(fd, KEY_TO_SALT_PADDING, SEEK_CUR) == -1) {
printf("Cannot seek to real block device salt\n");
goto errout;
}
if ( (cnt = read(fd, salt, SALT_LEN)) != SALT_LEN) {
printf("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,
const 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 retval = -1;
if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) {
printf("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)) {
printf("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)) {
printf("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);
//printf("cryptsetup params: '%s'\n", crypt_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;
if (ioctl(fd, DM_TABLE_LOAD, io)) {
printf("Cannot load dm-crypt mapping table.\n");
goto errout;
}
/* Resume this device to activate it */
ioctl_init(io, 4096, name, 0);
if (ioctl(fd, DM_DEV_SUSPEND, io)) {
printf("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(const 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 ) {
printf("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)) {
printf("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 decrypt_master_key(char *passwd, unsigned char *salt,
unsigned char *encrypted_master_key,
unsigned char *decrypted_master_key)
{
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
if (using_samsung_encryption) {
property_set("rw.km_fips_status", "ready");
return decrypt_EDK((dek_t*)decrypted_master_key, (edk_payload_t*)encrypted_master_key, passwd);
}
#endif
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 get_orig_mount_parms(
const char *mount_point, char *fs_type, char *real_blkdev,
unsigned long *mnt_flags, char *fs_options)
{
char mount_point2[PROPERTY_VALUE_MAX];
char fs_flags[PROPERTY_VALUE_MAX];
property_get("ro.crypto.fs_type", fs_type, "");
property_get("ro.crypto.fs_real_blkdev", real_blkdev, "");
property_get("ro.crypto.fs_mnt_point", mount_point2, "");
property_get("ro.crypto.fs_options", fs_options, "");
property_get("ro.crypto.fs_flags", fs_flags, "");
*mnt_flags = strtol(fs_flags, 0, 0);
if (strcmp(mount_point, mount_point2)) {
/* Consistency check. These should match. If not, something odd happened. */
return -1;
}
return 0;
}
static int get_orig_mount_parms_sd(
const char *mount_point, char *fs_type, char *real_blkdev)
{
char mount_point2[PROPERTY_VALUE_MAX];
property_get("ro.crypto.sd_fs_type", fs_type, "");
property_get("ro.crypto.sd_fs_real_blkdev", real_blkdev, "");
property_get("ro.crypto.sd_fs_mnt_point", mount_point2, "");
if (strcmp(mount_point, mount_point2)) {
/* Consistency check. These should match. If not, something odd happened. */
return -1;
}
return 0;
}
static int test_mount_encrypted_fs(
char *passwd, char *mount_point, char *label, char *crypto_blkdev)
{
struct crypt_mnt_ftr crypt_ftr;
/* Allocate enough space for a 256 bit key, but we may use less */
unsigned char encrypted_master_key[256], decrypted_master_key[32];
unsigned char salt[SALT_LEN];
char real_blkdev[MAXPATHLEN];
char fs_type[PROPERTY_VALUE_MAX];
char fs_options[PROPERTY_VALUE_MAX];
char tmp_mount_point[MAXPATHLEN];
unsigned long mnt_flags;
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") ) {
printf("encrypted fs already validated or not running with encryption, aborting %s\n", encrypted_state);
return -1;
}
if (get_orig_mount_parms(mount_point, fs_type, real_blkdev, &mnt_flags, fs_options)) {
printf("Error reading original mount parms for mount point %s\n", mount_point);
return -1;
}
if (get_crypt_ftr_and_key(real_blkdev, &crypt_ftr, encrypted_master_key, salt)) {
printf("Error getting crypt footer and key\n");
return -1;
}
//printf("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)) {
printf("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 ( mount(crypto_blkdev, tmp_mount_point, fs_type, MS_RDONLY, "") ) {
printf("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;
}
rmdir(tmp_mount_point);
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, sizeof(saved_master_key));
saved_data_blkdev = strdup(real_blkdev);
saved_mount_point = strdup(mount_point);
master_key_saved = 1;
rc = 0;
}
return rc;
}
static int test_mount_encrypted_fs_sd(
const char *passwd, const char *mount_point, const char *label)
{
char real_blkdev[MAXPATHLEN];
char crypto_blkdev[MAXPATHLEN];
char tmp_mount_point[MAXPATHLEN];
char encrypted_state[PROPERTY_VALUE_MAX];
char fs_type[PROPERTY_VALUE_MAX];
int rc;
property_get("ro.crypto.state", encrypted_state, "");
if ( !master_key_saved || strcmp(encrypted_state, "encrypted") ) {
printf("encrypted fs not yet validated or not running with encryption, aborting\n");
return -1;
}
if (get_orig_mount_parms_sd(mount_point, fs_type, real_blkdev)) {
printf("Error reading original mount parms for mount point %s\n", mount_point);
return -1;
}
rc = cryptfs_setup_volume(label, real_blkdev, crypto_blkdev);
if(rc){
printf("Error setting up cryptfs volume %s\n", real_blkdev);
return -1;
}
sprintf(tmp_mount_point, "%s/tmp_mnt", mount_point);
mkdir(tmp_mount_point, 0755);
if ( mount(crypto_blkdev, tmp_mount_point, fs_type, MS_RDONLY, "") ) {
printf("Error temp mounting decrypted block device\n");
delete_crypto_blk_dev(label);
} else {
/* Success, so just umount and we'll mount it properly when we restart
* the framework.
*/
umount(tmp_mount_point);
property_set("ro.crypto.sd_fs_crypto_blkdev", crypto_blkdev);
}
rmdir(tmp_mount_point);
return rc;
}
/*
* 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, const char *real_blkdev, char *crypto_blkdev)
{
struct crypt_mnt_ftr sd_crypt_ftr;
unsigned char key[256], salt[32];
struct stat statbuf;
int nr_sec, fd, rc;
/* 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;
}
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
if(using_samsung_encryption) {
if(!access("/efs/essiv", R_OK)){
strcpy(sd_crypt_ftr.crypto_type_name, "aes-cbc-plain:sha1");
}
else if(!access("/efs/cryptprop_essiv", R_OK)){
strcpy(sd_crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256");
}
}
#endif
sd_crypt_ftr.fs_size = nr_sec;
rc = create_crypto_blk_dev(
&sd_crypt_ftr, saved_master_key, real_blkdev, crypto_blkdev, label);
stat(crypto_blkdev, &statbuf);
return rc;
}
int cryptfs_crypto_complete(void)
{
return -1;
}
int cryptfs_check_passwd(const char *passwd)
{
char pwbuf[256];
char crypto_blkdev_data[MAXPATHLEN];
int rc = -1;
strcpy(pwbuf, passwd);
rc = test_mount_encrypted_fs(pwbuf, DATA_MNT_POINT, "userdata", crypto_blkdev_data);
#ifdef TW_INCLUDE_CRYPTO_SAMSUNG
if(using_samsung_encryption) {
int rc2 = 1;
#ifndef RECOVERY_SDCARD_ON_DATA
#ifdef TW_INTERNAL_STORAGE_PATH
// internal storage for non data/media devices
if(!rc) {
strcpy(pwbuf, passwd);
rc2 = test_mount_encrypted_fs_sd(
pwbuf, EXPAND(TW_INTERNAL_STORAGE_PATH),
EXPAND(TW_INTERNAL_STORAGE_MOUNT_POINT));
}
#endif
#endif
#ifdef TW_EXTERNAL_STORAGE_PATH
printf("Temp mounting /data\n");
// mount data so mount_ecryptfs_drive can access edk in /data/system/
rc2 = mount(crypto_blkdev_data, DATA_MNT_POINT, CRYPTO_FS_TYPE, MS_RDONLY, "");
// external sd
char decrypt_external[256], external_blkdev[256];
property_get("ro.crypto.external_encrypted", decrypt_external, "0");
// Mount the external storage as ecryptfs so that ecryptfs can act as a pass-through
if (!rc2 && strcmp(decrypt_external, "1") == 0) {
printf("Mounting external with ecryptfs...\n");
strcpy(pwbuf, passwd);
rc2 = mount_ecryptfs_drive(
pwbuf, EXPAND(TW_EXTERNAL_STORAGE_PATH),
EXPAND(TW_EXTERNAL_STORAGE_PATH), 0);
if (rc2 == 0)
property_set("ro.crypto.external_use_ecryptfs", "1");
else
property_set("ro.crypto.external_use_ecryptfs", "0");
} else {
printf("Unable to mount external storage with ecryptfs.\n");
umount(EXPAND(TW_EXTERNAL_STORAGE_PATH));
}
umount(DATA_MNT_POINT);
}
#endif // #ifdef TW_EXTERNAL_STORAGE_PATH
#endif // #ifdef TW_INCLUDE_CRYPTO_SAMSUNG
return rc;
}