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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/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 <openssl/sha.h>
#include <errno.h>
#include <ext4.h>
#include <linux/kdev_t.h>
#include <fs_mgr.h>
#include <time.h>
#include <math.h>
#include "cryptfs.h"
#define LOG_TAG "Cryptfs"
#include "cutils/log.h"
#include "cutils/properties.h"
#include "cutils/android_reboot.h"
#include "hardware_legacy/power.h"
#include <logwrap/logwrap.h>
#include "VolumeManager.h"
#include "VoldUtil.h"
#include "crypto_scrypt.h"
#include "Ext4Crypt.h"
#include "ext4_crypt_init_extensions.h"
#include "ext4_utils.h"
#include "f2fs_sparseblock.h"
#include "CheckBattery.h"
#include "Process.h"
#include <hardware/keymaster0.h>
#include <hardware/keymaster1.h>
#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 DEFAULT_HEX_PASSWORD "64656661756c745f70617373776f7264"
#define DEFAULT_PASSWORD "default_password"
#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 int previous_type;
#ifdef MINIVOLD
inline int release_wake_lock(const char* id) { return 0; }
inline int acquire_wake_lock(int lock, const char* id) { return 0; }
static const char* kMkExt4fsPath = "/sbin/mke2fs";
static const char* kMkF2fsPath = "/sbin/mkfs.f2fs";
#else
static const char* kMkExt4fsPath = "/system/bin/make_ext4fs";
static const char* kMkF2fsPath = "/system/bin/mkfs.f2fs";
#endif
#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 put_crypt_ftr_and_key(struct crypt_mnt_ftr *crypt_ftr);
static int test_mount_hw_encrypted_fs(struct crypt_mnt_ftr* crypt_ftr,
char *passwd, char *mount_point, char *label);
int cryptfs_changepw_hw_fde(int crypt_type, const char *currentpw,
const char *newpw);
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)) {
SLOGE("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;
}
char* fix_broken_cm12_pattern(const char* passwd)
{
size_t index, length;
bool is_broken = 0;
if (!passwd) {
return NULL;
}
length = strlen(passwd);
// Check password can be a broken cm12 pattern - it has something
// that isn't a 1-9 digit.
for (index = 0; index < length; index ++) {
if (passwd[index] < '1' || passwd[index] > '9') {
is_broken = 1;
}
}
if (!is_broken) return NULL;
// Allocate room for adjusted passwd and null terminate
char* adjusted = malloc((length*2) + 1);
unsigned int i, a;
unsigned char nibble;
for (i=0, a=0; i<length; i++, a+=2) {
/* For each byte, write out two ascii hex digits */
nibble = (passwd[i] >> 4) & 0xf;
adjusted[a] = nibble + (nibble > 10 ? 0x2c : 0x2d);
nibble = passwd[i] & 0xf;
if (!nibble) { nibble=0x10; adjusted[a]--; };
adjusted[a+1] = nibble + (nibble > 10 ? 0x56 : 0x2f);
}
adjusted[a] = '\0';
return adjusted;
}
static int verify_and_update_hw_fde_passwd(char *passwd,
struct crypt_mnt_ftr* crypt_ftr)
{
char* new_passwd = NULL;
unsigned char newpw[32] = {0};
int key_index = -1;
int passwd_updated = -1;
int ascii_passwd_updated = (crypt_ftr->flags & CRYPT_ASCII_PASSWORD_UPDATED);
key_index = verify_hw_fde_passwd(passwd, crypt_ftr);
if (key_index < 0) {
++crypt_ftr->failed_decrypt_count;
if (ascii_passwd_updated) {
SLOGI("Ascii password was updated");
} else {
/* Code in else part would execute only once:
* When device is upgraded from L->M release.
* Once upgraded, code flow should never come here.
* L release passed actual password in hex, so try with hex
* Each nible of passwd was encoded as a byte, so allocate memory
* twice of password len plus one more byte for null termination
*/
if (crypt_ftr->crypt_type == CRYPT_TYPE_DEFAULT) {
new_passwd = (char*)malloc(strlen(DEFAULT_HEX_PASSWORD) + 1);
if (new_passwd == NULL) {
SLOGE("System out of memory. Password verification incomplete");
goto out;
}
strlcpy(new_passwd, DEFAULT_HEX_PASSWORD, strlen(DEFAULT_HEX_PASSWORD) + 1);
} else {
if (crypt_ftr->crypt_type == CRYPT_TYPE_PATTERN) {
new_passwd = fix_broken_cm12_pattern(passwd);
}
if (new_passwd == NULL) { // not an old broken pattern
new_passwd = (char*)malloc(strlen(passwd) * 2 + 1);
if (new_passwd == NULL) {
SLOGE("System out of memory. Password verification incomplete");
goto out;
}
convert_key_to_hex_ascii((const unsigned char*)passwd,
strlen(passwd), new_passwd);
}
}
key_index = set_hw_device_encryption_key((const char*)new_passwd,
(char*) crypt_ftr->crypto_type_name);
if (key_index >=0) {
crypt_ftr->failed_decrypt_count = 0;
SLOGI("Hex password verified...will try to update with Ascii value");
/* Before updating password, tie that with keymaster to tie with ROT */
if (get_keymaster_hw_fde_passwd(passwd, newpw,
crypt_ftr->salt, crypt_ftr)) {
passwd_updated = update_hw_device_encryption_key(new_passwd,
passwd, (char*)crypt_ftr->crypto_type_name);
} else {
passwd_updated = update_hw_device_encryption_key(new_passwd,
(const char*)newpw, (char*)crypt_ftr->crypto_type_name);
}
if (passwd_updated >= 0) {
crypt_ftr->flags |= CRYPT_ASCII_PASSWORD_UPDATED;
SLOGI("Ascii password recorded and updated");
} else {
SLOGI("Passwd verified, could not update...Will try next time");
}
} else {
++crypt_ftr->failed_decrypt_count;
}
free(new_passwd);
}
} else {
if (!ascii_passwd_updated)
crypt_ftr->flags |= CRYPT_ASCII_PASSWORD_UPDATED;
}
out:
// update footer before leaving
put_crypt_ftr_and_key(crypt_ftr);
return key_index;
}
#endif
#ifndef MINIVOLD // no HALs in recovery...
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) {
ALOGE("could not find any keystore module");
goto err;
}
SLOGI("keymaster module name is %s", mod->name);
SLOGI("keymaster version is %d", mod->module_api_version);
*keymaster0_dev = NULL;
*keymaster1_dev = NULL;
if (mod->module_api_version == KEYMASTER_MODULE_API_VERSION_1_0) {
SLOGI("Found keymaster1 module, using keymaster1 API.");
rc = keymaster1_open(mod, keymaster1_dev);
} else {
SLOGI("Found keymaster0 module, using keymaster0 API.");
rc = keymaster0_open(mod, keymaster0_dev);
}
if (rc) {
ALOGE("could not open keymaster device in %s (%s)",
KEYSTORE_HARDWARE_MODULE_ID, strerror(-rc));
goto err;
}
return 0;
err:
*keymaster0_dev = NULL;
*keymaster1_dev = NULL;
return rc;
}
#endif
/* Should we use keymaster? */
static int keymaster_check_compatibility()
{
#ifdef MINIVOLD
return -1;
#else
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
int rc = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
SLOGE("Failed to init keymaster");
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;
#endif
}
/* Create a new keymaster key and store it in this footer */
static int keymaster_create_key(struct crypt_mnt_ftr *ftr)
{
#ifdef MINIVOLD // no HALs in recovery...
return -1;
#else
uint8_t* key = 0;
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
SLOGE("Failed to init keymaster");
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, ¶m_set,
&key_blob,
NULL /* characteristics */);
if (error != KM_ERROR_OK) {
SLOGE("Failed to generate keymaster1 key, error %d", 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(¶ms, '\0', sizeof(params));
params.public_exponent = RSA_EXPONENT;
params.modulus_size = RSA_KEY_SIZE;
if (keymaster0_dev->generate_keypair(keymaster0_dev, TYPE_RSA, ¶ms,
&key, &key_size)) {
SLOGE("Failed to generate keypair");
rc = -1;
goto out;
}
} else {
SLOGE("Cryptfs bug: keymaster_init succeeded but didn't initialize a device");
rc = -1;
goto out;
}
if (key_size > KEYMASTER_BLOB_SIZE) {
SLOGE("Keymaster key too large for crypto footer");
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;
#endif
}
/* 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)
{
#ifdef MINIVOLD // no HALs in recovery...
return -1;
#else
int rc = 0;
keymaster0_device_t *keymaster0_dev = 0;
keymaster1_device_t *keymaster1_dev = 0;
if (keymaster_init(&keymaster0_dev, &keymaster1_dev)) {
SLOGE("Failed to init keymaster");
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));
SLOGI("Signing safely-padded object");
break;
default:
SLOGE("Unknown KDF type %d", 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,
¶ms,
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,
¶m_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,
¶m_set, NULL /* out_params */,
&op_handle);
}
if (error != KM_ERROR_OK) {
SLOGE("Error starting keymaster signature transaction: %d", 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) {
SLOGE("Error sending data to keymaster signature transaction: %d", 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.
SLOGE("Keymaster update() did not consume all data.");
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) {
SLOGE("Error finishing keymaster signature transaction: %d", error);
rc = -1;
goto out;
}
*signature = (uint8_t*)tmp_sig.data;
*signature_size = tmp_sig.data_length;
} else {
SLOGE("Cryptfs bug: keymaster_init succeded but didn't initialize a device.");
rc = -1;
goto out;
}
out:
if (keymaster1_dev)
keymaster1_close(keymaster1_dev);
if (keymaster0_dev)
keymaster0_close(keymaster0_dev);
return rc;
#endif
}
/* 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;
extern struct fstab *fstab;
enum RebootType {reboot, recovery, shutdown};
static void cryptfs_reboot(enum RebootType rt)
{
switch(rt) {
case reboot:
property_set(ANDROID_RB_PROPERTY, "reboot");
break;
case recovery:
property_set(ANDROID_RB_PROPERTY, "reboot,recovery");
break;
case shutdown:
property_set(ANDROID_RB_PROPERTY, "shutdown");
break;
}
sleep(20);
/* Shouldn't get here, reboot should happen before sleep times out */
return;
}
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) {
strlcpy(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)) {
SLOGW("bad scrypt parameters '%s' should be like '12:8:1'; using defaults", 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_fs_size(char *dev)
{
int fd, block_size;
struct ext4_super_block sb;
off64_t len;
if ((fd = open(dev, O_RDONLY|O_CLOEXEC)) < 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);
if (le32_to_cpu(sb.s_magic) != EXT4_SUPER_MAGIC) {
SLOGE("Not a valid ext4 superblock");
return 0;
}
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 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;
char key_loc[PROPERTY_VALUE_MAX];
char real_blkdev[PROPERTY_VALUE_MAX];
int rc = -1;
if (!cached_data) {
fs_mgr_get_crypt_info(fstab, key_loc, real_blkdev, sizeof(key_loc));
if (!strcmp(key_loc, KEY_IN_FOOTER)) {
if ( (fd = open(real_blkdev, O_RDWR|O_CLOEXEC)) < 0) {
SLOGE("Cannot open real block device %s\n", real_blkdev);
return -1;
}
unsigned long nr_sec = 0;
get_blkdev_size(fd, &nr_sec);
if (nr_sec != 0) {
/* 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 {
SLOGE("Cannot get size of block device %s\n", real_blkdev);
}
close(fd);
} else {
strlcpy(cached_metadata_fname, key_loc, 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;
}
/* 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(struct crypt_mnt_ftr *crypt_ftr)
{
int fd;
unsigned int cnt;
/* starting_off is set to the SEEK_SET offset
* where the crypto structure starts
*/
off64_t starting_off;
int rc = -1;
char *fname = NULL;
struct stat statbuf;
if (get_crypt_ftr_info(&fname, &starting_off)) {
SLOGE("Unable to get crypt_ftr_info\n");
return -1;
}
if (fname[0] != '/') {
SLOGE("Unexpected value for crypto key location\n");
return -1;
}
if ( (fd = open(fname, O_RDWR | O_CREAT|O_CLOEXEC, 0600)) < 0) {
SLOGE("Cannot open footer file %s for put\n", fname);
return -1;
}
/* Seek to the start of the crypt footer */
if (lseek64(fd, starting_off, SEEK_SET) == -1) {
SLOGE("Cannot seek to real block device footer\n");
goto errout;
}
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;
}
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)) {
if (ftruncate(fd, 0x4000)) {
SLOGE("Cannot set footer file size\n");
goto errout;
}
}
/* Success! */
rc = 0;
errout:
close(fd);
return rc;
}
static inline int unix_read(int fd, void* buff, int len)
{
return TEMP_FAILURE_RETRY(read(fd, buff, len));
}
static inline int unix_write(int fd, const void* buff, int len)
{
return TEMP_FAILURE_RETRY(write(fd, buff, len));
}
static void init_empty_persist_data(struct crypt_persist_data *pdata, int len)
{
memset(pdata, 0, len);
pdata->persist_magic = PERSIST_DATA_MAGIC;
pdata->persist_valid_entries = 0;
}
/* A routine to update the passed in crypt_ftr to the lastest version.
* fd is open read/write on the device that holds the crypto footer and persistent
* data, crypt_ftr is a pointer to the struct to be updated, and offset is the
* absolute offset to the start of the crypt_mnt_ftr on the passed in fd.
*/
static void upgrade_crypt_ftr(int fd, struct crypt_mnt_ftr *crypt_ftr, off64_t offset)
{
int orig_major = crypt_ftr->major_version;
int orig_minor = crypt_ftr->minor_version;
if ((crypt_ftr->major_version == 1) && (crypt_ftr->minor_version == 0)) {
struct crypt_persist_data *pdata;
off64_t pdata_offset = offset + CRYPT_FOOTER_TO_PERSIST_OFFSET;
SLOGW("upgrading crypto footer to 1.1");
pdata = malloc(CRYPT_PERSIST_DATA_SIZE);
if (pdata == NULL) {
SLOGE("Cannot allocate persisent data\n");
return;
}
memset(pdata, 0, CRYPT_PERSIST_DATA_SIZE);
/* Need to initialize the persistent data area */
if (lseek64(fd, pdata_offset, SEEK_SET) == -1) {
SLOGE("Cannot seek to persisent data offset\n");
free(pdata);
return;
}
/* Write all zeros to the first copy, making it invalid */
unix_write(fd, pdata, CRYPT_PERSIST_DATA_SIZE);
/* Write a valid but empty structure to the second copy */
init_empty_persist_data(pdata, CRYPT_PERSIST_DATA_SIZE);
unix_write(fd, pdata, CRYPT_PERSIST_DATA_SIZE);
/* Update the footer */
crypt_ftr->persist_data_size = CRYPT_PERSIST_DATA_SIZE;
crypt_ftr->persist_data_offset[0] = pdata_offset;
crypt_ftr->persist_data_offset[1] = pdata_offset + CRYPT_PERSIST_DATA_SIZE;
crypt_ftr->minor_version = 1;
free(pdata);
}
if ((crypt_ftr->major_version == 1) && (crypt_ftr->minor_version == 1)) {
SLOGW("upgrading crypto footer to 1.2");
/* But keep the old kdf_type.
* It will get updated later to KDF_SCRYPT after the password has been verified.
*/
crypt_ftr->kdf_type = KDF_PBKDF2;
get_device_scrypt_params(crypt_ftr);
crypt_ftr->minor_version = 2;
}
if ((crypt_ftr->major_version == 1) && (crypt_ftr->minor_version == 2)) {
SLOGW("upgrading crypto footer to 1.3");
crypt_ftr->crypt_type = CRYPT_TYPE_PASSWORD;
crypt_ftr->minor_version = 3;
}
if ((orig_major != crypt_ftr->major_version) || (orig_minor != crypt_ftr->minor_version)) {
if (lseek64(fd, offset, SEEK_SET) == -1) {
SLOGE("Cannot seek to crypt footer\n");
return;
}
unix_write(fd, crypt_ftr, sizeof(struct crypt_mnt_ftr));
}
}
static int get_crypt_ftr_and_key(struct crypt_mnt_ftr *crypt_ftr)
{
int fd;
unsigned int cnt;
off64_t starting_off;
int rc = -1;
char *fname = NULL;
struct stat statbuf;
if (get_crypt_ftr_info(&fname, &starting_off)) {
SLOGE("Unable to get crypt_ftr_info\n");
return -1;
}
if (fname[0] != '/') {
SLOGE("Unexpected value for crypto key location\n");
return -1;
}
if ( (fd = open(fname, O_RDWR|O_CLOEXEC)) < 0) {
SLOGE("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)) {
SLOGE("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) {
SLOGE("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)) {
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 != CURRENT_MAJOR_VERSION) {
SLOGE("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) {
SLOGW("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);
}