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cryptfs.cpp
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cryptfs.cpp
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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_utils/ext4_crypt.h>
#include <ext4_utils/ext4_utils.h>
#include <linux/kdev_t.h>
#include <fs_mgr.h>
#include <time.h>
#include <math.h>
#include <selinux/selinux.h>
#include "cryptfs.h"
#include "secontext.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 "ScryptParameters.h"
#include "Utils.h"
#include "VolumeManager.h"
#include "VoldUtil.h"
#include "Ext4Crypt.h"
#include "f2fs_sparseblock.h"
#include "EncryptInplace.h"
#include "Process.h"
#include "Keymaster.h"
#include "android-base/properties.h"
#include "android-base/stringprintf.h"
#include <bootloader_message/bootloader_message.h>
#ifdef CONFIG_HW_DISK_ENCRYPTION
#include <cryptfs_hw.h>
#endif
extern "C" {
#include <crypto_scrypt.h>
}
using android::base::StringPrintf;
using namespace std::chrono_literals;
#define UNUSED __attribute__((unused))
#define DM_CRYPT_BUF_SIZE 4096
#define HASH_COUNT 2000
constexpr size_t INTERMEDIATE_KEY_LEN_BYTES = 16;
constexpr size_t INTERMEDIATE_IV_LEN_BYTES = 16;
constexpr size_t INTERMEDIATE_BUF_SIZE =
(INTERMEDIATE_KEY_LEN_BYTES + INTERMEDIATE_IV_LEN_BYTES);
// SCRYPT_LEN is used by struct crypt_mnt_ftr for its intermediate key.
static_assert(INTERMEDIATE_BUF_SIZE == SCRYPT_LEN,
"Mismatch of intermediate key sizes");
#define KEY_IN_FOOTER "footer"
#define DEFAULT_HEX_PASSWORD "64656661756c745f70617373776f7264"
#define DEFAULT_PASSWORD "default_password"
#define CRYPTO_BLOCK_DEVICE "userdata"
#define BREADCRUMB_FILE "/data/misc/vold/convert_fde"
#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 KEY_LEN_BYTES 16
#define RETRY_MOUNT_ATTEMPTS 10
#define RETRY_MOUNT_DELAY_SECONDS 1
#define CREATE_CRYPTO_BLK_DEV_FLAGS_ALLOW_ENCRYPT_OVERRIDE (1)
static int put_crypt_ftr_and_key(struct crypt_mnt_ftr* crypt_ftr);
static unsigned char saved_master_key[MAX_KEY_LEN];
static char *saved_mount_point;
static int master_key_saved = 0;
static struct crypt_persist_data *persist_data = NULL;
static int previous_type;
#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,
const char *passwd, const char *mount_point, const char *label);
int cryptfs_changepw_hw_fde(int crypt_type, const char *currentpw,
const char *newpw);
int cryptfs_check_passwd_hw(char *passwd);
int cryptfs_get_master_key(struct crypt_mnt_ftr* ftr, const char* password,
unsigned char* master_key);
static void convert_key_to_hex_ascii_for_upgrade(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 ? 0x57 : 0x30);
nibble = master_key[i] & 0xf;
master_key_ascii[a + 1] = nibble + (nibble > 9 ? 0x57 : 0x30);
}
/* Add the null termination */
master_key_ascii[a] = '\0';
}
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(const 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;
}
static int verify_and_update_hw_fde_passwd(const 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 {
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_for_upgrade((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
/* Should we use keymaster? */
static int keymaster_check_compatibility()
{
return keymaster_compatibility_cryptfs_scrypt();
}
/* Create a new keymaster key and store it in this footer */
static int keymaster_create_key(struct crypt_mnt_ftr *ftr)
{
if (ftr->keymaster_blob_size) {
SLOGI("Already have key");
return 0;
}
int rc = keymaster_create_key_for_cryptfs_scrypt(RSA_KEY_SIZE, RSA_EXPONENT,
KEYMASTER_CRYPTFS_RATE_LIMIT, ftr->keymaster_blob, KEYMASTER_BLOB_SIZE,
&ftr->keymaster_blob_size);
if (rc) {
if (ftr->keymaster_blob_size > KEYMASTER_BLOB_SIZE) {
SLOGE("Keymaster key blob too large");
ftr->keymaster_blob_size = 0;
}
SLOGE("Failed to generate keypair");
return -1;
}
return 0;
}
/* 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)
{
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, std::min((size_t)RSA_KEY_SIZE_BYTES - 1, object_size));
SLOGI("Signing safely-padded object");
break;
default:
SLOGE("Unknown KDF type %d", ftr->kdf_type);
return -1;
}
for (;;) {
auto result = keymaster_sign_object_for_cryptfs_scrypt(
ftr->keymaster_blob, ftr->keymaster_blob_size, KEYMASTER_CRYPTFS_RATE_LIMIT, to_sign,
to_sign_size, signature, signature_size);
switch (result) {
case KeymasterSignResult::ok:
return 0;
case KeymasterSignResult::upgrade:
break;
default:
return -1;
}
SLOGD("Upgrading key");
if (keymaster_upgrade_key_for_cryptfs_scrypt(
RSA_KEY_SIZE, RSA_EXPONENT, KEYMASTER_CRYPTFS_RATE_LIMIT, ftr->keymaster_blob,
ftr->keymaster_blob_size, ftr->keymaster_blob, KEYMASTER_BLOB_SIZE,
&ftr->keymaster_blob_size) != 0) {
SLOGE("Failed to upgrade key");
return -1;
}
if (put_crypt_ftr_and_key(ftr) != 0) {
SLOGE("Failed to write upgraded key to disk");
}
SLOGD("Key upgraded successfully");
}
}
/* 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;
enum class RebootType {reboot, recovery, shutdown};
static void cryptfs_reboot(RebootType rt)
{
switch (rt) {
case RebootType::reboot:
property_set(ANDROID_RB_PROPERTY, "reboot");
break;
case RebootType::recovery:
property_set(ANDROID_RB_PROPERTY, "reboot,recovery");
break;
case RebootType::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));
}
}
namespace {
struct CryptoType;
// Use to get the CryptoType in use on this device.
const CryptoType &get_crypto_type();
struct CryptoType {
// We should only be constructing CryptoTypes as part of
// supported_crypto_types[]. We do it via this pseudo-builder pattern,
// which isn't pure or fully protected as a concession to being able to
// do it all at compile time. Add new CryptoTypes in
// supported_crypto_types[] below.
constexpr CryptoType() : CryptoType(nullptr, nullptr, 0xFFFFFFFF) {}
constexpr CryptoType set_keysize(uint32_t size) const {
return CryptoType(this->property_name, this->crypto_name, size);
}
constexpr CryptoType set_property_name(const char *property) const {
return CryptoType(property, this->crypto_name, this->keysize);
}
constexpr CryptoType set_crypto_name(const char *crypto) const {
return CryptoType(this->property_name, crypto, this->keysize);
}
constexpr const char *get_property_name() const { return property_name; }
constexpr const char *get_crypto_name() const { return crypto_name; }
constexpr uint32_t get_keysize() const { return keysize; }
private:
const char *property_name;
const char *crypto_name;
uint32_t keysize;
constexpr CryptoType(const char *property, const char *crypto,
uint32_t ksize)
: property_name(property), crypto_name(crypto), keysize(ksize) {}
friend const CryptoType &get_crypto_type();
static const CryptoType &get_device_crypto_algorithm();
};
// We only want to parse this read-only property once. But we need to wait
// until the system is initialized before we can read it. So we use a static
// scoped within this function to get it only once.
const CryptoType &get_crypto_type() {
static CryptoType crypto_type = CryptoType::get_device_crypto_algorithm();
return crypto_type;
}
constexpr CryptoType default_crypto_type = CryptoType()
.set_property_name("AES-128-CBC")
.set_crypto_name("aes-cbc-essiv:sha256")
.set_keysize(16);
constexpr CryptoType supported_crypto_types[] = {
default_crypto_type,
CryptoType()
.set_property_name("adiantum")
.set_crypto_name("xchacha12,aes-adiantum-plain64")
.set_keysize(32),
// Add new CryptoTypes here. Order is not important.
};
// ---------- START COMPILE-TIME SANITY CHECK BLOCK -------------------------
// We confirm all supported_crypto_types have a small enough keysize and
// had both set_property_name() and set_crypto_name() called.
template <typename T, size_t N>
constexpr size_t array_length(T (&)[N]) { return N; }
constexpr bool indexOutOfBoundsForCryptoTypes(size_t index) {
return (index >= array_length(supported_crypto_types));
}
constexpr bool isValidCryptoType(const CryptoType &crypto_type) {
return ((crypto_type.get_property_name() != nullptr) &&
(crypto_type.get_crypto_name() != nullptr) &&
(crypto_type.get_keysize() <= MAX_KEY_LEN));
}
// Note in C++11 that constexpr functions can only have a single line.
// So our code is a bit convoluted (using recursion instead of a loop),
// but it's asserting at compile time that all of our key lengths are valid.
constexpr bool validateSupportedCryptoTypes(size_t index) {
return indexOutOfBoundsForCryptoTypes(index) ||
(isValidCryptoType(supported_crypto_types[index]) &&
validateSupportedCryptoTypes(index + 1));
}
static_assert(validateSupportedCryptoTypes(0),
"We have a CryptoType with keysize > MAX_KEY_LEN or which was "
"incompletely constructed.");
// ---------- END COMPILE-TIME SANITY CHECK BLOCK -------------------------
// Don't call this directly, use get_crypto_type(), which caches this result.
const CryptoType &CryptoType::get_device_crypto_algorithm() {
constexpr char CRYPT_ALGO_PROP[] = "ro.crypto.fde_algorithm";
char paramstr[PROPERTY_VALUE_MAX];
property_get(CRYPT_ALGO_PROP, paramstr,
default_crypto_type.get_property_name());
for (auto const &ctype : supported_crypto_types) {
if (strcmp(paramstr, ctype.get_property_name()) == 0) {
return ctype;
}
}
ALOGE("Invalid name (%s) for %s. Defaulting to %s\n", paramstr,
CRYPT_ALGO_PROP, default_crypto_type.get_property_name());
return default_crypto_type;
}
} // namespace
/**
* 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) {
char paramstr[PROPERTY_VALUE_MAX];
int Nf, rf, pf;
property_get(SCRYPT_PROP, paramstr, SCRYPT_DEFAULTS);
if (!parse_scrypt_parameters(paramstr, &Nf, &rf, &pf)) {
SLOGW("bad scrypt parameters '%s' should be like '12:8:1'; using defaults", paramstr);
parse_scrypt_parameters(SCRYPT_DEFAULTS, &Nf, &rf, &pf);
}
ftr->N_factor = Nf;
ftr->r_factor = rf;
ftr->p_factor = pf;
}
uint32_t cryptfs_get_keysize() {
return get_crypto_type().get_keysize();
}
const char *cryptfs_get_crypto_name() {
return get_crypto_type().get_crypto_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|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_default, 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;
}
/* Set sha256 checksum in structure */
static void set_ftr_sha(struct crypt_mnt_ftr *crypt_ftr)
{
SHA256_CTX c;
SHA256_Init(&c);
memset(crypt_ftr->sha256, 0, sizeof(crypt_ftr->sha256));
SHA256_Update(&c, crypt_ftr, sizeof(*crypt_ftr));
SHA256_Final(crypt_ftr->sha256, &c);
}
/* 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;
set_ftr_sha(crypt_ftr);
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 bool check_ftr_sha(const struct crypt_mnt_ftr *crypt_ftr)
{
struct crypt_mnt_ftr copy;
memcpy(©, crypt_ftr, sizeof(copy));
set_ftr_sha(©);
return memcmp(copy.sha256, crypt_ftr->sha256, sizeof(copy.sha256)) == 0;
}
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 = (crypt_persist_data *)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;
}
// We risk buffer overflows with oversized keys, so we just reject them.
// 0-sized keys are problematic (essentially by-passing encryption), and
// AES-CBC key wrapping only works for multiples of 16 bytes.
if ((crypt_ftr->keysize == 0) || ((crypt_ftr->keysize % 16) != 0) ||
(crypt_ftr->keysize > MAX_KEY_LEN)) {
SLOGE("Invalid keysize (%u) for block device %s; Must be non-zero, "
"divisible by 16, and <= %d\n", crypt_ftr->keysize, fname,
MAX_KEY_LEN);
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);
}
/* Success! */
rc = 0;
errout:
close(fd);
return rc;
}
static int validate_persistent_data_storage(struct crypt_mnt_ftr *crypt_ftr)
{
if (crypt_ftr->persist_data_offset[0] + crypt_ftr->persist_data_size >
crypt_ftr->persist_data_offset[1]) {
SLOGE("Crypt_ftr persist data regions overlap");
return -1;
}
if (crypt_ftr->persist_data_offset[0] >= crypt_ftr->persist_data_offset[1]) {
SLOGE("Crypt_ftr persist data region 0 starts after region 1");
return -1;
}
if (((crypt_ftr->persist_data_offset[1] + crypt_ftr->persist_data_size) -
(crypt_ftr->persist_data_offset[0] - CRYPT_FOOTER_TO_PERSIST_OFFSET)) >
CRYPT_FOOTER_OFFSET) {
SLOGE("Persistent data extends past crypto footer");
return -1;
}
return 0;
}
static int load_persistent_data(void)
{
struct crypt_mnt_ftr crypt_ftr;
struct crypt_persist_data *pdata = NULL;
char encrypted_state[PROPERTY_VALUE_MAX];
char *fname;
int found = 0;
int fd;
int ret;
int i;
if (persist_data) {
/* Nothing to do, we've already loaded or initialized it */
return 0;
}
/* If not encrypted, just allocate an empty table and initialize it */
property_get("ro.crypto.state", encrypted_state, "");
if (strcmp(encrypted_state, "encrypted") ) {
pdata = (crypt_persist_data*)malloc(CRYPT_PERSIST_DATA_SIZE);
if (pdata) {
init_empty_persist_data(pdata, CRYPT_PERSIST_DATA_SIZE);
persist_data = pdata;
return 0;
}
return -1;
}
if(get_crypt_ftr_and_key(&crypt_ftr)) {
return -1;
}
if ((crypt_ftr.major_version < 1)
|| (crypt_ftr.major_version == 1 && crypt_ftr.minor_version < 1)) {
SLOGE("Crypt_ftr version doesn't support persistent data");
return -1;
}
if (get_crypt_ftr_info(&fname, NULL)) {
return -1;
}
ret = validate_persistent_data_storage(&crypt_ftr);
if (ret) {
return -1;
}
fd = open(fname, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
SLOGE("Cannot open %s metadata file", fname);
return -1;
}
pdata = (crypt_persist_data*)malloc(crypt_ftr.persist_data_size);
if (pdata == NULL) {
SLOGE("Cannot allocate memory for persistent data");
goto err;
}
for (i = 0; i < 2; i++) {
if (lseek64(fd, crypt_ftr.persist_data_offset[i], SEEK_SET) < 0) {
SLOGE("Cannot seek to read persistent data on %s", fname);
goto err2;
}
if (unix_read(fd, pdata, crypt_ftr.persist_data_size) < 0){
SLOGE("Error reading persistent data on iteration %d", i);
goto err2;
}
if (pdata->persist_magic == PERSIST_DATA_MAGIC) {
found = 1;
break;
}
}
if (!found) {
SLOGI("Could not find valid persistent data, creating");
init_empty_persist_data(pdata, crypt_ftr.persist_data_size);
}
/* Success */