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gerrit.twrp.me / android_bootable_recovery / 67940a2a28bf7f07531d7fcf7bafb86f42e1646b / . / crypto / lollipop / cryptfs.c
blob: 56f10b92b6b53a6f8ac6cac612f54739c9642625 [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 <linux/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <ctype.h>
#include <fcntl.h>
#include <inttypes.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 <errno.h>
#include <linux/kdev_t.h>
#include <time.h>
#include "cryptfs.h"
#include "cutils/properties.h"
#include "crypto_scrypt.h"
#ifndef TW_CRYPTO_HAVE_KEYMASTERX
#include <hardware/keymaster.h>
#else
#include <stdbool.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <hardware/keymaster0.h>
#include <hardware/keymaster1.h>
#endif
#ifndef min /* already defined by windows.h */
#define min(a, b) ((a) < (b) ? (a) : (b))
#endif
#define UNUSED __attribute__((unused))
#define UNUSED __attribute__((unused))
#ifdef CONFIG_HW_DISK_ENCRYPTION
#include "cryptfs_hw.h"
#endif
#define DM_CRYPT_BUF_SIZE 4096
#define HASH_COUNT 2000
#define KEY_LEN_BYTES 16
#define IV_LEN_BYTES 16
#define KEY_IN_FOOTER "footer"
#define EXT4_FS 1
#define F2FS_FS 2
#define TABLE_LOAD_RETRIES 10
#define RSA_KEY_SIZE 2048
#define RSA_KEY_SIZE_BYTES (RSA_KEY_SIZE / 8)
#define RSA_EXPONENT 0x10001
#define KEYMASTER_CRYPTFS_RATE_LIMIT 1 // Maximum one try per second
#define RETRY_MOUNT_ATTEMPTS 10
#define RETRY_MOUNT_DELAY_SECONDS 1
char *me = "cryptfs";
static unsigned char saved_master_key[KEY_LEN_BYTES];
static char *saved_mount_point;
static int master_key_saved = 0;
static struct crypt_persist_data *persist_data = NULL;
static char key_fname[PROPERTY_VALUE_MAX] = "";
static char real_blkdev[PROPERTY_VALUE_MAX] = "";
static char file_system[PROPERTY_VALUE_MAX] = "";
#ifdef CONFIG_HW_DISK_ENCRYPTION
static int scrypt_keymaster(const char *passwd, const unsigned char *salt,
unsigned char *ikey, void *params);
static void convert_key_to_hex_ascii(const unsigned char *master_key,
unsigned int keysize, char *master_key_ascii);
static int get_keymaster_hw_fde_passwd(const char* passwd, unsigned char* newpw,
unsigned char* salt,
const struct crypt_mnt_ftr *ftr)
{
/* if newpw updated, return 0
* if newpw not updated return -1
*/
int rc = -1;
if (should_use_keymaster()) {
if (scrypt_keymaster(passwd, salt, newpw, (void*)ftr)) {
printf("scrypt failed");
} else {
rc = 0;
}
}
return rc;
}
static int verify_hw_fde_passwd(char *passwd, struct crypt_mnt_ftr* crypt_ftr)
{
unsigned char newpw[32] = {0};
int key_index;
if (get_keymaster_hw_fde_passwd(passwd, newpw, crypt_ftr->salt, crypt_ftr))
key_index = set_hw_device_encryption_key(passwd,
(char*) crypt_ftr->crypto_type_name);
else
key_index = set_hw_device_encryption_key((const char*)newpw,
(char*) crypt_ftr->crypto_type_name);
return key_index;
}
#endif
void set_partition_data(const char* block_device, const char* key_location, const char* fs)
{
strcpy(key_fname, key_location);
strcpy(real_blkdev, block_device);
strcpy(file_system, fs);
}
#ifndef TW_CRYPTO_HAVE_KEYMASTERX
static int keymaster_init(keymaster_device_t **keymaster_dev)
{
int rc;
const hw_module_t* mod;
rc = hw_get_module_by_class(KEYSTORE_HARDWARE_MODULE_ID, NULL, &mod);
if (rc) {
printf("could not find any keystore module\n");
goto out;
}
rc = keymaster_open(mod, keymaster_dev);
if (rc) {
printf("could not open keymaster device in %s (%s)\n",
KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc));
goto out;
}
return 0;
out:
*keymaster_dev = NULL;
return rc;
}
/* Should we use keymaster? */
static int keymaster_check_compatibility()
{
keymaster_device_t *keymaster_dev = 0;
int rc = 0;
if (keymaster_init(&keymaster_dev)) {
printf("Failed to init keymaster\n");
rc = -1;
goto out;
}
printf("keymaster version is %d\n", keymaster_dev->common.module->module_api_version);
#if (KEYMASTER_HEADER_VERSION >= 3)
if (keymaster_dev->common.module->module_api_version
< KEYMASTER_MODULE_API_VERSION_0_3) {
rc = 0;
goto out;
}
if (keymaster_dev->flags & KEYMASTER_BLOBS_ARE_STANDALONE) {
rc = 1;
}
#endif
out:
keymaster_close(keymaster_dev);
return rc;
}
/* Create a new keymaster key and store it in this footer */
static int keymaster_create_key(struct crypt_mnt_ftr *ftr)
{
uint8_t* key = 0;
keymaster_device_t *keymaster_dev = 0;
if (keymaster_init(&keymaster_dev)) {
printf("Failed to init keymaster\n");
return -1;
}
int rc = 0;
keymaster_rsa_keygen_params_t params;
memset(&params, '\0', sizeof(params));
params.public_exponent = RSA_EXPONENT;
params.modulus_size = RSA_KEY_SIZE;
size_t key_size;
if (keymaster_dev->generate_keypair(keymaster_dev, TYPE_RSA, &params,
&key, &key_size)) {
printf("Failed to generate keypair\n");
rc = -1;
goto out;
}
if (key_size > KEYMASTER_BLOB_SIZE) {
printf("Keymaster key too large for crypto footer\n");
rc = -1;
goto out;
}
memcpy(ftr->keymaster_blob, key, key_size);
ftr->keymaster_blob_size = key_size;
out:
keymaster_close(keymaster_dev);
free(key);
return rc;
}
/* This signs the given object using the keymaster key. */
static int keymaster_sign_object(struct crypt_mnt_ftr *ftr,
const unsigned char *object,
const size_t object_size,
unsigned char **signature,
size_t *signature_size)
{
int rc = 0;
keymaster_device_t *keymaster_dev = 0;
if (keymaster_init(&keymaster_dev)) {
printf("Failed to init keymaster\n");
return -1;
}
/* We currently set the digest type to DIGEST_NONE because it's the
* only supported value for keymaster. A similar issue exists with
* PADDING_NONE. Long term both of these should likely change.
*/
keymaster_rsa_sign_params_t params;
params.digest_type = DIGEST_NONE;
params.padding_type = PADDING_NONE;
unsigned char to_sign[RSA_KEY_SIZE_BYTES];
size_t to_sign_size = sizeof(to_sign);
memset(to_sign, 0, RSA_KEY_SIZE_BYTES);
// To sign a message with RSA, the message must satisfy two
// constraints:
//
// 1. The message, when interpreted as a big-endian numeric value, must
// be strictly less than the public modulus of the RSA key. Note
// that because the most significant bit of the public modulus is
// guaranteed to be 1 (else it's an (n-1)-bit key, not an n-bit
// key), an n-bit message with most significant bit 0 always
// satisfies this requirement.
//
// 2. The message must have the same length in bits as the public
// modulus of the RSA key. This requirement isn't mathematically
// necessary, but is necessary to ensure consistency in
// implementations.
switch (ftr->kdf_type) {
case KDF_SCRYPT_KEYMASTER_UNPADDED:
// This is broken: It produces a message which is shorter than
// the public modulus, failing criterion 2.
memcpy(to_sign, object, object_size);
to_sign_size = object_size;
printf("Signing unpadded object\n");
break;
case KDF_SCRYPT_KEYMASTER_BADLY_PADDED:
// This is broken: Since the value of object is uniformly
// distributed, it produces a message that is larger than the
// public modulus with probability 0.25.
memcpy(to_sign, object, min(RSA_KEY_SIZE_BYTES, object_size));
printf("Signing end-padded object\n");
break;
case KDF_SCRYPT_KEYMASTER:
// This ensures the most significant byte of the signed message
// is zero. We could have zero-padded to the left instead, but
// this approach is slightly more robust against changes in
// object size. However, it's still broken (but not unusably
// so) because we really should be using a proper RSA padding
// function, such as OAEP.
//
// TODO(paullawrence): When keymaster 0.4 is available, change
// this to use the padding options it provides.
memcpy(to_sign + 1, object, min(RSA_KEY_SIZE_BYTES - 1, object_size));
printf("Signing safely-padded object\n");
break;
default:
printf("Unknown KDF type %d\n", ftr->kdf_type);
return -1;
}
rc = keymaster_dev->sign_data(keymaster_dev,
&params,
ftr->keymaster_blob,
ftr->keymaster_blob_size,
to_sign,
to_sign_size,
signature,
signature_size);
keymaster_close(keymaster_dev);
return rc;
}
#else //#ifndef TW_CRYPTO_HAVE_KEYMASTERX
static int keymaster_init(keymaster0_device_t **keymaster0_dev,
keymaster1_device_t **keymaster1_dev)
{
int rc;
const hw_module_t* mod;
rc = hw_get_module_by_class(KEYSTORE_HARDWARE_MODULE_ID, NULL, &mod);
if (rc) {
printf("could not find any keystore module\n");
goto err;
}
printf("keymaster module name is %s\n", mod->name);
printf("keymaster version is %d\n", mod->module_api_version);
*keymaster0_dev = NULL;
*keymaster1_dev = NULL;
if (mod->module_api_version == KEYMASTER_MODULE_API_VERSION_1_0) {
printf("Found keymaster1 module, using keymaster1 API.\n");
rc = keymaster1_open(mod, keymaster1_dev);
} else {
printf("Found keymaster0 module, using keymaster0 API.\n");
rc = keymaster0_open(mod, keymaster0_dev);
}
if (rc) {
printf("could not open keymaster device in %s (%s)\n",
KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc));
goto err;
}
return 0;
err:
*keymaster0_dev = NULL;
*keymaster1_dev = NULL;
return rc;
}
/* Should we use keymaster? */
static int keymaster_check_compatibility()
{
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
int rc = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
printf("Failed to init keymaster\n");
rc = -1;
goto out;
}
if (keymaster1_dev) {
rc = 1;
goto out;
}
// TODO(swillden): Check to see if there's any reason to require v0.3. I think v0.1 and v0.2
// should work.
if (keymaster0_dev->common.module->module_api_version
< KEYMASTER_MODULE_API_VERSION_0_3) {
rc = 0;
goto out;
}
if (!(keymaster0_dev->flags & KEYMASTER_SOFTWARE_ONLY) &&
(keymaster0_dev->flags & KEYMASTER_BLOBS_ARE_STANDALONE)) {
rc = 1;
}
out:
if (keymaster1_dev) {
keymaster1_close(keymaster1_dev);
}
if (keymaster0_dev) {
keymaster0_close(keymaster0_dev);
}
return rc;
}
/* Create a new keymaster key and store it in this footer */
static int keymaster_create_key(struct crypt_mnt_ftr *ftr)
{
uint8_t* key = 0;
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
printf("Failed to init keymaster\n");
return -1;
}
int rc = 0;
size_t key_size = 0;
if (keymaster1_dev) {
keymaster_key_param_t params[] = {
/* Algorithm & size specifications. Stick with RSA for now. Switch to AES later. */
keymaster_param_enum(KM_TAG_ALGORITHM, KM_ALGORITHM_RSA),
keymaster_param_int(KM_TAG_KEY_SIZE, RSA_KEY_SIZE),
keymaster_param_long(KM_TAG_RSA_PUBLIC_EXPONENT, RSA_EXPONENT),
/* The only allowed purpose for this key is signing. */
keymaster_param_enum(KM_TAG_PURPOSE, KM_PURPOSE_SIGN),
/* Padding & digest specifications. */
keymaster_param_enum(KM_TAG_PADDING, KM_PAD_NONE),
keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_NONE),
/* Require that the key be usable in standalone mode. File system isn't available. */
keymaster_param_enum(KM_TAG_BLOB_USAGE_REQUIREMENTS, KM_BLOB_STANDALONE),
/* No auth requirements, because cryptfs is not yet integrated with gatekeeper. */
keymaster_param_bool(KM_TAG_NO_AUTH_REQUIRED),
/* Rate-limit key usage attempts, to rate-limit brute force */
keymaster_param_int(KM_TAG_MIN_SECONDS_BETWEEN_OPS, KEYMASTER_CRYPTFS_RATE_LIMIT),
};
keymaster_key_param_set_t param_set = { params, sizeof(params)/sizeof(*params) };
keymaster_key_blob_t key_blob;
keymaster_error_t error = keymaster1_dev->generate_key(keymaster1_dev, &param_set,
&key_blob,
NULL /* characteristics */);
if (error != KM_ERROR_OK) {
printf("Failed to generate keymaster1 key, error %d\n", error);
rc = -1;
goto out;
}
key = (uint8_t*)key_blob.key_material;
key_size = key_blob.key_material_size;
}
else if (keymaster0_dev) {
keymaster_rsa_keygen_params_t params;
memset(&params, '\0', sizeof(params));
params.public_exponent = RSA_EXPONENT;
params.modulus_size = RSA_KEY_SIZE;
if (keymaster0_dev->generate_keypair(keymaster0_dev, TYPE_RSA, &params,
&key, &key_size)) {
printf("Failed to generate keypair\n");
rc = -1;
goto out;
}
} else {
printf("Cryptfs bug: keymaster_init succeeded but didn't initialize a device\n");
rc = -1;
goto out;
}
if (key_size > KEYMASTER_BLOB_SIZE) {
printf("Keymaster key too large for crypto footer\n");
rc = -1;
goto out;
}
memcpy(ftr->keymaster_blob, key, key_size);
ftr->keymaster_blob_size = key_size;
out:
if (keymaster0_dev)
keymaster0_close(keymaster0_dev);
if (keymaster1_dev)
keymaster1_close(keymaster1_dev);
free(key);
return rc;
}
/* This signs the given object using the keymaster key. */
static int keymaster_sign_object(struct crypt_mnt_ftr *ftr,
const unsigned char *object,
const size_t object_size,
unsigned char **signature,
size_t *signature_size)
{
int rc = 0;
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
printf("Failed to init keymaster\n");
rc = -1;
goto out;
}
unsigned char to_sign[RSA_KEY_SIZE_BYTES];
size_t to_sign_size = sizeof(to_sign);
memset(to_sign, 0, RSA_KEY_SIZE_BYTES);
// To sign a message with RSA, the message must satisfy two
// constraints:
//
// 1. The message, when interpreted as a big-endian numeric value, must
// be strictly less than the public modulus of the RSA key. Note
// that because the most significant bit of the public modulus is
// guaranteed to be 1 (else it's an (n-1)-bit key, not an n-bit
// key), an n-bit message with most significant bit 0 always
// satisfies this requirement.
//
// 2. The message must have the same length in bits as the public
// modulus of the RSA key. This requirement isn't mathematically
// necessary, but is necessary to ensure consistency in
// implementations.
switch (ftr->kdf_type) {
case KDF_SCRYPT_KEYMASTER:
// This ensures the most significant byte of the signed message
// is zero. We could have zero-padded to the left instead, but
// this approach is slightly more robust against changes in
// object size. However, it's still broken (but not unusably
// so) because we really should be using a proper deterministic
// RSA padding function, such as PKCS1.
memcpy(to_sign + 1, object, min(RSA_KEY_SIZE_BYTES - 1, object_size));
printf("Signing safely-padded object\n");
break;
default:
printf("Unknown KDF type %d\n", ftr->kdf_type);
rc = -1;
goto out;
}
if (keymaster0_dev) {
keymaster_rsa_sign_params_t params;
params.digest_type = DIGEST_NONE;
params.padding_type = PADDING_NONE;
rc = keymaster0_dev->sign_data(keymaster0_dev,
&params,
ftr->keymaster_blob,
ftr->keymaster_blob_size,
to_sign,
to_sign_size,
signature,
signature_size);
goto out;
} else if (keymaster1_dev) {
keymaster_key_blob_t key = { ftr->keymaster_blob, ftr->keymaster_blob_size };
keymaster_key_param_t params[] = {
keymaster_param_enum(KM_TAG_PADDING, KM_PAD_NONE),
keymaster_param_enum(KM_TAG_DIGEST, KM_DIGEST_NONE),
};
keymaster_key_param_set_t param_set = { params, sizeof(params)/sizeof(*params) };
keymaster_operation_handle_t op_handle;
keymaster_error_t error = keymaster1_dev->begin(keymaster1_dev, KM_PURPOSE_SIGN, &key,
&param_set, NULL /* out_params */,
&op_handle);
if (error == KM_ERROR_KEY_RATE_LIMIT_EXCEEDED) {
// Key usage has been rate-limited. Wait a bit and try again.
sleep(KEYMASTER_CRYPTFS_RATE_LIMIT);
error = keymaster1_dev->begin(keymaster1_dev, KM_PURPOSE_SIGN, &key,
&param_set, NULL /* out_params */,
&op_handle);
}
if (error != KM_ERROR_OK) {
printf("Error starting keymaster signature transaction: %d\n", error);
rc = -1;
goto out;
}
keymaster_blob_t input = { to_sign, to_sign_size };
size_t input_consumed;
error = keymaster1_dev->update(keymaster1_dev, op_handle, NULL /* in_params */,
&input, &input_consumed, NULL /* out_params */,
NULL /* output */);
if (error != KM_ERROR_OK) {
printf("Error sending data to keymaster signature transaction: %d\n", error);
rc = -1;
goto out;
}
if (input_consumed != to_sign_size) {
// This should never happen. If it does, it's a bug in the keymaster implementation.
printf("Keymaster update() did not consume all data.\n");
keymaster1_dev->abort(keymaster1_dev, op_handle);
rc = -1;
goto out;
}
keymaster_blob_t tmp_sig;
error = keymaster1_dev->finish(keymaster1_dev, op_handle, NULL /* in_params */,
NULL /* verify signature */, NULL /* out_params */,
&tmp_sig);
if (error != KM_ERROR_OK) {
printf("Error finishing keymaster signature transaction: %d\n", error);
rc = -1;
goto out;
}
*signature = (uint8_t*)tmp_sig.data;
*signature_size = tmp_sig.data_length;
} else {
printf("Cryptfs bug: keymaster_init succeded but didn't initialize a device.\n");
rc = -1;
goto out;
}
out:
if (keymaster1_dev)
keymaster1_close(keymaster1_dev);
if (keymaster0_dev)
keymaster0_close(keymaster0_dev);
return rc;
}
#endif //#ifndef TW_CRYPTO_HAVE_KEYMASTERX
/* Store password when userdata is successfully decrypted and mounted.
* Cleared by cryptfs_clear_password
*
* To avoid a double prompt at boot, we need to store the CryptKeeper
* password and pass it to KeyGuard, which uses it to unlock KeyStore.
* Since the entire framework is torn down and rebuilt after encryption,
* we have to use a daemon or similar to store the password. Since vold
* is secured against IPC except from system processes, it seems a reasonable
* place to store this.
*
* password should be cleared once it has been used.
*
* password is aged out after password_max_age_seconds seconds.
*/
static char* password = 0;
static int password_expiry_time = 0;
static const int password_max_age_seconds = 60;
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));
}
}
/**
* Gets the default device scrypt parameters for key derivation time tuning.
* The parameters should lead to about one second derivation time for the
* given device.
*/
static void get_device_scrypt_params(struct crypt_mnt_ftr *ftr) {
const int default_params[] = SCRYPT_DEFAULTS;
int params[] = SCRYPT_DEFAULTS;
char paramstr[PROPERTY_VALUE_MAX];
char *token;
char *saveptr;
int i;
property_get(SCRYPT_PROP, paramstr, "");
if (paramstr[0] != '\0') {
/*
* The token we're looking for should be three integers separated by
* colons (e.g., "12:8:1"). Scan the property to make sure it matches.
*/
for (i = 0, token = strtok_r(paramstr, ":", &saveptr);
token != NULL && i < 3;
i++, token = strtok_r(NULL, ":", &saveptr)) {
char *endptr;
params[i] = strtol(token, &endptr, 10);
/*
* Check that there was a valid number and it's 8-bit. If not,
* break out and the end check will take the default values.
*/
if ((*token == '\0') || (*endptr != '\0') || params[i] < 0 || params[i] > 255) {
break;
}
}
/*
* If there were not enough tokens or a token was malformed (not an
* integer), it will end up here and the default parameters can be
* taken.
*/
if ((i != 3) || (token != NULL)) {
printf("bad scrypt parameters '%s' should be like '12:8:1'; using defaults\n", paramstr);
memcpy(params, default_params, sizeof(params));
}
}
ftr->N_factor = params[0];
ftr->r_factor = params[1];
ftr->p_factor = params[2];
}
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;
}
static int get_crypt_ftr_info(char **metadata_fname, off64_t *off)
{
static int cached_data = 0;
static off64_t cached_off = 0;
static char cached_metadata_fname[PROPERTY_VALUE_MAX] = "";
int fd;
unsigned int nr_sec;
int rc = -1;
if (!cached_data) {
printf("get_crypt_ftr_info crypto key location: '%s'\n", key_fname);
if (!strcmp(key_fname, KEY_IN_FOOTER)) {
if ( (fd = open(real_blkdev, O_RDWR)) < 0) {
printf("Cannot open real block device %s\n", real_blkdev);
return -1;
}
if ((nr_sec = get_blkdev_size(fd))) {
/* 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.
*/
strlcpy(cached_metadata_fname, real_blkdev, sizeof(cached_metadata_fname));
cached_off = ((off64_t)nr_sec * 512) - CRYPT_FOOTER_OFFSET;
cached_data = 1;
} else {
printf("Cannot get size of block device %s\n", real_blkdev);
}
close(fd);
} else {
strlcpy(cached_metadata_fname, key_fname, sizeof(cached_metadata_fname));
cached_off = 0;
cached_data = 1;
}
}
if (cached_data) {
if (metadata_fname) {
*metadata_fname = cached_metadata_fname;
}
if (off) {
*off = cached_off;
}
rc = 0;
}
return rc;
}
static int get_crypt_ftr_and_key(struct crypt_mnt_ftr *crypt_ftr)
{
int fd;
unsigned int nr_sec, cnt;
off64_t starting_off;
int rc = -1;
char *fname = NULL;
struct stat statbuf;
if (get_crypt_ftr_info(&fname, &starting_off)) {
printf("Unable to get crypt_ftr_info\n");
return -1;
}
if (fname[0] != '/') {
printf("Unexpected value for crypto key location\n");
return -1;
}
if ( (fd = open(fname, O_RDWR)) < 0) {
printf("Cannot open footer file %s for get\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)) {
printf("footer file %s is not the expected size!\n", fname);
goto errout;
}
/* Seek to the start of the crypt footer */
if (lseek64(fd, starting_off, SEEK_SET) == -1) {
printf("Cannot seek to real block device footer\n");
goto errout;
}
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) {
printf("Bad magic for real block device %s\n", fname);
goto errout;
}
if (crypt_ftr->major_version != CURRENT_MAJOR_VERSION) {
printf("Cannot understand major version %d real block device footer; expected %d\n",
crypt_ftr->major_version, CURRENT_MAJOR_VERSION);
goto errout;
}
if (crypt_ftr->minor_version > CURRENT_MINOR_VERSION) {
printf("Warning: crypto footer minor version %d, expected <= %d, continuing...\n",
crypt_ftr->minor_version, CURRENT_MINOR_VERSION);
}
/* If this is a verion 1.0 crypt_ftr, make it a 1.1 crypt footer, and update the
* copy on disk before returning.
*/
/*if (crypt_ftr->minor_version < CURRENT_MINOR_VERSION) {
upgrade_crypt_ftr(fd, crypt_ftr, starting_off);
}*/
/* Success! */
rc = 0;
errout:
close(fd);
return rc;
}
static int hexdigit (char c)
{
if (c >= '0' && c <= '9') return c - '0';
c = tolower(c);
if (c >= 'a' && c <= 'f') return c - 'a' + 10;
return -1;
}
static unsigned char* convert_hex_ascii_to_key(const char* master_key_ascii,
unsigned int* out_keysize)
{
unsigned int i;
*out_keysize = 0;
size_t size = strlen (master_key_ascii);
if (size % 2) {
printf("Trying to convert ascii string of odd length\n");
return NULL;
}
unsigned char* master_key = (unsigned char*) malloc(size / 2);
if (master_key == 0) {
printf("Cannot allocate\n");
return NULL;
}
for (i = 0; i < size; i += 2) {
int high_nibble = hexdigit (master_key_ascii[i]);
int low_nibble = hexdigit (master_key_ascii[i + 1]);
if(high_nibble < 0 || low_nibble < 0) {
printf("Invalid hex string\n");
free (master_key);
return NULL;
}
master_key[*out_keysize] = high_nibble * 16 + low_nibble;
(*out_keysize)++;
}
return master_key;
}
/* Convert a binary key of specified length into an ascii hex string equivalent,
* without the leading 0x and with null termination
*/
static void convert_key_to_hex_ascii(const 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, const unsigned char *master_key,
const 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;
#ifdef CONFIG_HW_DISK_ENCRYPTION
if(is_hw_disk_encryption((char*)crypt_ftr->crypto_type_name)) {
strlcpy(tgt->target_type, "req-crypt",DM_MAX_TYPE_NAME);
if (is_ice_enabled())
convert_key_to_hex_ascii(master_key, sizeof(int), master_key_ascii);
else
convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii);
}
else {
convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii);
strlcpy(tgt->target_type, "crypt", DM_MAX_TYPE_NAME);
}
#else
convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii);
strlcpy(tgt->target_type, "crypt", DM_MAX_TYPE_NAME);
#endif
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);
printf("%s: target_type = %s\n", __func__, tgt->target_type);
printf("%s: real_blk_name = %s, extra_params = %s\n", __func__, 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;
}
printf("%i\n", errno);
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 flag;
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) {
#ifdef CONFIG_HW_DISK_ENCRYPTION
if (is_hw_fde_enabled()) {
flag = (!strcmp(v->name, "crypt") || !strcmp(v->name, "req-crypt"));
} else {
flag = (!strcmp(v->name, "crypt"));
}
printf("get_dm_crypt_version flag: %i, name: '%s'\n", flag, v->name);
if (flag) {
#else
if (! strcmp(v->name, "crypt")) {
#endif
/* 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, const 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=0;
int i;
int retval = -1;
int version[3];
char *extra_params;
int load_count;
#ifdef CONFIG_HW_DISK_ENCRYPTION
char encrypted_state[PROPERTY_VALUE_MAX] = {0};
char progress[PROPERTY_VALUE_MAX] = {0};
#endif
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 %i\n", errno);
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);
#ifdef CONFIG_HW_DISK_ENCRYPTION
if(is_hw_disk_encryption((char*)crypt_ftr->crypto_type_name)) {
/* Set fde_enabled if either FDE completed or in-progress */
property_get("ro.crypto.state", encrypted_state, ""); /* FDE completed */
property_get("vold.encrypt_progress", progress, ""); /* FDE in progress */
if (!strcmp(encrypted_state, "encrypted") || strcmp(progress, "")) {
if (is_ice_enabled())
extra_params = "fde_enabled ice";
else
extra_params = "fde_enabled";
} else
extra_params = "fde_disabled";
} else {
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";
printf("Enabling support for allow_discards in dmcrypt.\n");
}
}
}
#else
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";
printf("Enabling support for allow_discards in dmcrypt.\n");
}
}
#endif
load_count = load_crypto_mapping_table(crypt_ftr, master_key, real_blk_name, name,
fd, extra_params);
if (load_count < 0) {
printf("Cannot load dm-crypt mapping table.\n");
goto errout;
} else if (load_count > 1) {
printf("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)) {
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;
}
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 ) {
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 int pbkdf2(const char *passwd, const unsigned char *salt,
unsigned char *ikey, void *params UNUSED)
{
printf("Using pbkdf2 for cryptfs KDF\n");
/* Turn the password into a key and IV that can decrypt the master key */
unsigned int keysize;
char* master_key = (char*)convert_hex_ascii_to_key(passwd, &keysize);
if (!master_key) return -1;
PKCS5_PBKDF2_HMAC_SHA1(master_key, keysize, salt, SALT_LEN,
HASH_COUNT, KEY_LEN_BYTES+IV_LEN_BYTES, ikey);
memset(master_key, 0, keysize);
free (master_key);
return 0;
}
static int scrypt(const char *passwd, const unsigned char *salt,
unsigned char *ikey, void *params)
{
printf("Using scrypt for cryptfs KDF\n");
struct crypt_mnt_ftr *ftr = (struct crypt_mnt_ftr *) params;
int N = 1 << ftr->N_factor;
int r = 1 << ftr->r_factor;
int p = 1 << ftr->p_factor;
/* Turn the password into a key and IV that can decrypt the master key */
unsigned int keysize;
unsigned char* master_key = convert_hex_ascii_to_key(passwd, &keysize);
if (!master_key) return -1;
crypto_scrypt(master_key, keysize, salt, SALT_LEN, N, r, p, ikey,
KEY_LEN_BYTES + IV_LEN_BYTES);
memset(master_key, 0, keysize);
free (master_key);
return 0;
}
static int scrypt_keymaster(const char *passwd, const unsigned char *salt,
unsigned char *ikey, void *params)
{
printf("Using scrypt with keymaster for cryptfs KDF\n");
int rc;
unsigned int key_size;
size_t signature_size;
unsigned char* signature;
struct crypt_mnt_ftr *ftr = (struct crypt_mnt_ftr *) params;
int N = 1 << ftr->N_factor;
int r = 1 << ftr->r_factor;
int p = 1 << ftr->p_factor;
unsigned char* master_key = convert_hex_ascii_to_key(passwd, &key_size);
if (!master_key) {
printf("Failed to convert passwd from hex\n");
return -1;
}
rc = crypto_scrypt(master_key, key_size, salt, SALT_LEN,
N, r, p, ikey, KEY_LEN_BYTES + IV_LEN_BYTES);
memset(master_key, 0, key_size);
free(master_key);
if (rc) {
printf("scrypt failed\n");
return -1;
}
if (keymaster_sign_object(ftr, ikey, KEY_LEN_BYTES + IV_LEN_BYTES,
&signature, &signature_size)) {
printf("Signing failed\n");
return -1;
}
rc = crypto_scrypt(signature, signature_size, salt, SALT_LEN,
N, r, p, ikey, KEY_LEN_BYTES + IV_LEN_BYTES);
free(signature);
if (rc) {
printf("scrypt failed\n");
return -1;
}
return 0;
}
static int decrypt_master_key_aux(char *passwd, unsigned char *salt,
unsigned char *encrypted_master_key,
unsigned char *decrypted_master_key,
kdf_func kdf, void *kdf_params,
unsigned char** intermediate_key,
size_t* intermediate_key_size)
{
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 an intermediate key and IV that can decrypt the
master key */
if (kdf(passwd, salt, ikey, kdf_params)) {
printf("kdf failed\n");
return -1;
}
/* 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;
}
#ifndef TW_CRYPTO_HAVE_KEYMASTERX
if (! EVP_DecryptFinal(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) {
#else
if (! EVP_DecryptFinal_ex(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) {
#endif
return -1;
}
if (decrypted_len + final_len != KEY_LEN_BYTES) {
return -1;
}
/* Copy intermediate key if needed by params */
if (intermediate_key && intermediate_key_size) {
*intermediate_key = (unsigned char*) malloc(KEY_LEN_BYTES);
if (intermediate_key) {
memcpy(*intermediate_key, ikey, KEY_LEN_BYTES);
*intermediate_key_size = KEY_LEN_BYTES;
}
}
return 0;
}
static void get_kdf_func(struct crypt_mnt_ftr *ftr, kdf_func *kdf, void** kdf_params)
{
if (ftr->kdf_type == KDF_SCRYPT_KEYMASTER_UNPADDED ||
ftr->kdf_type == KDF_SCRYPT_KEYMASTER_BADLY_PADDED ||
ftr->kdf_type == KDF_SCRYPT_KEYMASTER) {
*kdf = scrypt_keymaster;
*kdf_params = ftr;
} else if (ftr->kdf_type == KDF_SCRYPT) {
*kdf = scrypt;
*kdf_params = ftr;
} else {
*kdf = pbkdf2;
*kdf_params = NULL;
}
}
static int decrypt_master_key(char *passwd, unsigned char *decrypted_master_key,
struct crypt_mnt_ftr *crypt_ftr,
unsigned char** intermediate_key,
size_t* intermediate_key_size)
{
kdf_func kdf;
void *kdf_params;
int ret;
get_kdf_func(crypt_ftr, &kdf, &kdf_params);
ret = decrypt_master_key_aux(passwd, crypt_ftr->salt, crypt_ftr->master_key,
decrypted_master_key, kdf, kdf_params,
intermediate_key, intermediate_key_size);
if (ret != 0) {
printf("failure decrypting master key\n");
}
return ret;
}
static int test_mount_encrypted_fs(struct crypt_mnt_ftr* crypt_ftr,
char *passwd, char *mount_point, char *label)
{
/* Allocate enough space for a 256 bit key, but we may use less */
unsigned char decrypted_master_key[32];
char crypto_blkdev[MAXPATHLEN];
char tmp_mount_point[64];
int rc = 0;
kdf_func kdf;
void *kdf_params;
int use_keymaster = 0;
int upgrade = 0;
unsigned char* intermediate_key = 0;
size_t intermediate_key_size = 0;
printf("crypt_ftr->fs_size = %lld\n", crypt_ftr->fs_size);
if (! (crypt_ftr->flags & CRYPT_MNT_KEY_UNENCRYPTED) ) {
if (decrypt_master_key(passwd, decrypted_master_key, crypt_ftr,
&intermediate_key, &intermediate_key_size)) {
printf("Failed to decrypt master key\n");
rc = -1;
goto errout;
}
}
#ifdef CONFIG_HW_DISK_ENCRYPTION
int key_index = 0;
if(is_hw_disk_encryption((char*)crypt_ftr->crypto_type_name)) {
key_index = verify_hw_fde_passwd(passwd, crypt_ftr);
if (key_index < 0) {
rc = 1;
goto errout;
}
else {
if (is_ice_enabled()) {
if (create_crypto_blk_dev(crypt_ftr, (unsigned char*)&key_index,
real_blkdev, crypto_blkdev, label)) {
printf("Error creating decrypted block device");
rc = -1;
goto errout;
}
} else {
if (create_crypto_blk_dev(crypt_ftr, decrypted_master_key,
real_blkdev, crypto_blkdev, label)) {
printf("Error creating decrypted block device");
rc = -1;
goto errout;
}
}
}
} else {
/* in case HW FDE is delivered through OTA and device is already encrypted
* using SW FDE, we should let user continue using SW FDE until userdata is
* wiped.
*/
if (create_crypto_blk_dev(crypt_ftr, decrypted_master_key,
real_blkdev, crypto_blkdev, label)) {
printf("Error creating decrypted block device");
rc = -1;
goto errout;
}
}
#else
// Create crypto block device - all (non fatal) code paths
// need it
if (create_crypto_blk_dev(crypt_ftr, decrypted_master_key,
real_blkdev, crypto_blkdev, label)) {
printf("Error creating decrypted block device\n");
rc = -1;
goto errout;
}
#endif
/* Work out if the problem is the password or the data */
unsigned char scrypted_intermediate_key[sizeof(crypt_ftr->
scrypted_intermediate_key)];
int N = 1 << crypt_ftr->N_factor;
int r = 1 << crypt_ftr->r_factor;
int p = 1 << crypt_ftr->p_factor;
rc = crypto_scrypt(intermediate_key, intermediate_key_size,
crypt_ftr->salt, sizeof(crypt_ftr->salt),
N, r, p, scrypted_intermediate_key,
sizeof(scrypted_intermediate_key));
// Does the key match the crypto footer?
if (rc == 0 && memcmp(scrypted_intermediate_key,
crypt_ftr->scrypted_intermediate_key,
sizeof(scrypted_intermediate_key)) == 0) {
printf("Password matches\n");
rc = 0;
} else {
/* Try mounting the file system anyway, just in case the problem's with
* the footer, not the key. */
sprintf(tmp_mount_point, "%s/tmp_mnt", mount_point);
mkdir(tmp_mount_point, 0755);
if (mount(crypto_blkdev, tmp_mount_point, file_system, 0, NULL) != 0) {
printf("Error temp mounting decrypted block device '%s'\n", crypto_blkdev);
delete_crypto_blk_dev(label);
rc = 1;
} else {
/* Success! */
printf("Password did not match but decrypted drive mounted - continue\n");
umount(tmp_mount_point);
rc = 0;
}
}
if (rc == 0) {
// Don't increment the failed attempt counter as it doesn't
// make sense to do so in TWRP
/* 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);
// TWRP shouldn't change the stored key
}
errout:
if (intermediate_key) {
memset(intermediate_key, 0, intermediate_key_size);
free(intermediate_key);
}
return rc;
}
int check_unmounted_and_get_ftr(struct crypt_mnt_ftr* crypt_ftr)
{
char encrypted_state[PROPERTY_VALUE_MAX];
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\n");
//return -1;
}
if (get_crypt_ftr_and_key(crypt_ftr)) {
printf("Error getting crypt footer and key\n");
return -1;
}
return 0;
}
int cryptfs_check_footer()
{
int rc = -1;
struct crypt_mnt_ftr crypt_ftr;
rc = get_crypt_ftr_and_key(&crypt_ftr);
return rc;
}
int cryptfs_check_passwd(char *passwd)
{
struct crypt_mnt_ftr crypt_ftr;
int rc;
if (!passwd) {
printf("cryptfs_check_passwd: passwd is NULL!\n");
return -1;
}
rc = check_unmounted_and_get_ftr(&crypt_ftr);
if (rc)
return rc;
rc = test_mount_encrypted_fs(&crypt_ftr, passwd,
DATA_MNT_POINT, "userdata");
// try falling back to Lollipop hex passwords
if (rc) {
int hex_pass_len = strlen(passwd) * 2 + 1;
char *hex_passwd = (char *)malloc(hex_pass_len);
if (hex_passwd) {
convert_key_to_hex_ascii((unsigned char *)passwd,
strlen(passwd), hex_passwd);
rc = test_mount_encrypted_fs(&crypt_ftr, hex_passwd,
DATA_MNT_POINT, "userdata");
memset(hex_passwd, 0, hex_pass_len);
free(hex_passwd);
}
}
return rc;
}
/* Returns type of the password, default, pattern, pin or password.
*/
int cryptfs_get_password_type(void)
{
struct crypt_mnt_ftr crypt_ftr;
if (get_crypt_ftr_and_key(&crypt_ftr)) {
printf("Error getting crypt footer and key\n");
return -1;
}
if (crypt_ftr.flags & CRYPT_INCONSISTENT_STATE) {
return -1;
}
return crypt_ftr.crypt_type;
}
/*
* Called by vold when it's asked to mount an encrypted external
* storage volume. The incoming partition has no crypto header/footer,
* as any metadata is been stored in a separate, small partition.
*
* out_crypto_blkdev must be MAXPATHLEN.
*/
int cryptfs_setup_ext_volume(const char* label, const char* real_blkdev,
const unsigned char* key, int keysize, char* out_crypto_blkdev) {
int fd = open(real_blkdev, O_RDONLY|O_CLOEXEC);
if (fd == -1) {
printf("Failed to open %s: %s", real_blkdev, strerror(errno));
return -1;
}
unsigned long nr_sec = 0;
nr_sec = get_blkdev_size(fd);
close(fd);
if (nr_sec == 0) {
printf("Failed to get size of %s: %s", real_blkdev, strerror(errno));
return -1;
}
struct crypt_mnt_ftr ext_crypt_ftr;
memset(&ext_crypt_ftr, 0, sizeof(ext_crypt_ftr));
ext_crypt_ftr.fs_size = nr_sec;
ext_crypt_ftr.keysize = keysize;
strcpy((char*) ext_crypt_ftr.crypto_type_name, "aes-cbc-essiv:sha256");
return create_crypto_blk_dev(&ext_crypt_ftr, key, real_blkdev,
out_crypto_blkdev, label);
}
/*
* Called by vold when it's asked to unmount an encrypted external
* storage volume.
*/
int cryptfs_revert_ext_volume(const char* label) {
return delete_crypto_blk_dev((char*) label);
}