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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.
*/
#define LOG_TAG "Cryptfs"
#include "cryptfs.h"
#include "Checkpoint.h"
#include "CryptoType.h"
#include "EncryptInplace.h"
#include "FsCrypt.h"
#include "Keymaster.h"
#include "Process.h"
#include "ScryptParameters.h"
#include "Utils.h"
#include "VoldUtil.h"
#include "VolumeManager.h"
#include <android-base/parseint.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <bootloader_message/bootloader_message.h>
#include <cutils/android_reboot.h>
#include <cutils/properties.h>
#include <ext4_utils/ext4_utils.h>
#include <f2fs_sparseblock.h>
#include <fs_mgr.h>
#include <fscrypt/fscrypt.h>
#include <libdm/dm.h>
#include <log/log.h>
#include <logwrap/logwrap.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <selinux/selinux.h>
#include <wakelock/wakelock.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <libgen.h>
#include <linux/kdev_t.h>
#include <math.h>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <chrono>
#include <thread>
#ifdef CONFIG_HW_DISK_ENCRYPTION
#include <linux/dm-ioctl.h>
#include <sys/ioctl.h>
#include <cryptfs_hw.h>
#endif
extern "C" {
#include <crypto_scrypt.h>
}
using android::base::ParseUint;
using android::base::StringPrintf;
using android::fs_mgr::GetEntryForMountPoint;
using android::vold::CryptoType;
using android::vold::KeyBuffer;
using android::vold::KeyGeneration;
using namespace android::dm;
using namespace std::chrono_literals;
/* The current cryptfs version */
#define CURRENT_MAJOR_VERSION 1
#define CURRENT_MINOR_VERSION 3
#define CRYPT_FOOTER_TO_PERSIST_OFFSET 0x1000
#define CRYPT_PERSIST_DATA_SIZE 0x1000
#define MAX_CRYPTO_TYPE_NAME_LEN 64
#define MAX_KEY_LEN 48
#define SALT_LEN 16
#define SCRYPT_LEN 32
/* definitions of flags in the structure below */
#define CRYPT_MNT_KEY_UNENCRYPTED 0x1 /* The key for the partition is not encrypted. */
#define CRYPT_ENCRYPTION_IN_PROGRESS \
0x2 /* Encryption partially completed, \
encrypted_upto valid*/
#define CRYPT_INCONSISTENT_STATE \
0x4 /* Set when starting encryption, clear when \
exit cleanly, either through success or \
correctly marked partial encryption */
#define CRYPT_DATA_CORRUPT \
0x8 /* Set when encryption is fine, but the \
underlying volume is corrupt */
#define CRYPT_FORCE_ENCRYPTION \
0x10 /* Set when it is time to encrypt this \
volume on boot. Everything in this \
structure is set up correctly as \
though device is encrypted except \
that the master key is encrypted with the \
default password. */
#define CRYPT_FORCE_COMPLETE \
0x20 /* Set when the above encryption cycle is \
complete. On next cryptkeeper entry, match \
the password. If it matches fix the master \
key and remove this flag. */
/* Allowed values for type in the structure below */
#define CRYPT_TYPE_PASSWORD \
0 /* master_key is encrypted with a password \
* Must be zero to be compatible with pre-L \
* devices where type is always password.*/
#define CRYPT_TYPE_DEFAULT \
1 /* master_key is encrypted with default \
* password */
#define CRYPT_TYPE_PATTERN 2 /* master_key is encrypted with a pattern */
#define CRYPT_TYPE_PIN 3 /* master_key is encrypted with a pin */
#define CRYPT_TYPE_MAX_TYPE 3 /* type cannot be larger than this value */
#define CRYPT_MNT_MAGIC 0xD0B5B1C4
#define PERSIST_DATA_MAGIC 0xE950CD44
/* Key Derivation Function algorithms */
#define KDF_PBKDF2 1
#define KDF_SCRYPT 2
/* Algorithms 3 & 4 deprecated before shipping outside of google, so removed */
#define KDF_SCRYPT_KEYMASTER 5
/* Maximum allowed keymaster blob size. */
#define KEYMASTER_BLOB_SIZE 2048
/* __le32 and __le16 defined in system/extras/ext4_utils/ext4_utils.h */
#define __le8 unsigned char
#if !defined(SHA256_DIGEST_LENGTH)
#define SHA256_DIGEST_LENGTH 32
#endif
/* This structure starts 16,384 bytes before the end of a hardware
* partition that is encrypted, or in a separate partition. It's location
* is specified by a property set in init.<device>.rc.
* The structure allocates 48 bytes for a key, but the real key size is
* specified in the struct. Currently, the code is hardcoded to use 128
* bit keys.
* The fields after salt are only valid in rev 1.1 and later stuctures.
* Obviously, the filesystem does not include the last 16 kbytes
* of the partition if the crypt_mnt_ftr lives at the end of the
* partition.
*/
struct crypt_mnt_ftr {
__le32 magic; /* See above */
__le16 major_version;
__le16 minor_version;
__le32 ftr_size; /* in bytes, not including key following */
__le32 flags; /* See above */
__le32 keysize; /* in bytes */
__le32 crypt_type; /* how master_key is encrypted. Must be a
* CRYPT_TYPE_XXX value */
__le64 fs_size; /* Size of the encrypted fs, in 512 byte sectors */
__le32 failed_decrypt_count; /* count of # of failed attempts to decrypt and
mount, set to 0 on successful mount */
unsigned char crypto_type_name[MAX_CRYPTO_TYPE_NAME_LEN]; /* The type of encryption
needed to decrypt this
partition, null terminated */
__le32 spare2; /* ignored */
unsigned char master_key[MAX_KEY_LEN]; /* The encrypted key for decrypting the filesystem */
unsigned char salt[SALT_LEN]; /* The salt used for this encryption */
__le64 persist_data_offset[2]; /* Absolute offset to both copies of crypt_persist_data
* on device with that info, either the footer of the
* real_blkdevice or the metadata partition. */
__le32 persist_data_size; /* The number of bytes allocated to each copy of the
* persistent data table*/
__le8 kdf_type; /* The key derivation function used. */
/* scrypt parameters. See www.tarsnap.com/scrypt/scrypt.pdf */
__le8 N_factor; /* (1 << N) */
__le8 r_factor; /* (1 << r) */
__le8 p_factor; /* (1 << p) */
__le64 encrypted_upto; /* If we are in state CRYPT_ENCRYPTION_IN_PROGRESS and
we have to stop (e.g. power low) this is the last
encrypted 512 byte sector.*/
__le8 hash_first_block[SHA256_DIGEST_LENGTH]; /* When CRYPT_ENCRYPTION_IN_PROGRESS
set, hash of first block, used
to validate before continuing*/
/* key_master key, used to sign the derived key which is then used to generate
* the intermediate key
* This key should be used for no other purposes! We use this key to sign unpadded
* data, which is acceptable but only if the key is not reused elsewhere. */
__le8 keymaster_blob[KEYMASTER_BLOB_SIZE];
__le32 keymaster_blob_size;
/* Store scrypt of salted intermediate key. When decryption fails, we can
check if this matches, and if it does, we know that the problem is with the
drive, and there is no point in asking the user for more passwords.
Note that if any part of this structure is corrupt, this will not match and
we will continue to believe the user entered the wrong password. In that
case the only solution is for the user to enter a password enough times to
force a wipe.
Note also that there is no need to worry about migration. If this data is
wrong, we simply won't recognise a right password, and will continue to
prompt. On the first password change, this value will be populated and
then we will be OK.
*/
unsigned char scrypted_intermediate_key[SCRYPT_LEN];
/* sha of this structure with this element set to zero
Used when encrypting on reboot to validate structure before doing something
fatal
*/
unsigned char sha256[SHA256_DIGEST_LENGTH];
};
/* Persistant data that should be available before decryption.
* Things like airplane mode, locale and timezone are kept
* here and can be retrieved by the CryptKeeper UI to properly
* configure the phone before asking for the password
* This is only valid if the major and minor version above
* is set to 1.1 or higher.
*
* This is a 4K structure. There are 2 copies, and the code alternates
* writing one and then clearing the previous one. The reading
* code reads the first valid copy it finds, based on the magic number.
* The absolute offset to the first of the two copies is kept in rev 1.1
* and higher crypt_mnt_ftr structures.
*/
struct crypt_persist_entry {
char key[PROPERTY_KEY_MAX];
char val[PROPERTY_VALUE_MAX];
};
/* Should be exactly 4K in size */
struct crypt_persist_data {
__le32 persist_magic;
__le32 persist_valid_entries;
__le32 persist_spare[30];
struct crypt_persist_entry persist_entry[0];
};
static int wait_and_unmount(const char* mountpoint, bool kill);
typedef int (*kdf_func)(const char* passwd, const unsigned char* salt, unsigned char* ikey,
void* params);
#define UNUSED __attribute__((unused))
#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
constexpr CryptoType aes_128_cbc = CryptoType()
.set_config_name("AES-128-CBC")
.set_kernel_name("aes-cbc-essiv:sha256")
.set_keysize(16);
constexpr CryptoType supported_crypto_types[] = {aes_128_cbc, android::vold::adiantum};
static_assert(validateSupportedCryptoTypes(MAX_KEY_LEN, supported_crypto_types,
array_length(supported_crypto_types)),
"We have a CryptoType with keysize > MAX_KEY_LEN or which was "
"incompletely constructed.");
static const CryptoType& get_crypto_type() {
// 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.
static CryptoType crypto_type =
lookup_crypto_algorithm(supported_crypto_types, array_length(supported_crypto_types),
aes_128_cbc, "ro.crypto.fde_algorithm");
return crypto_type;
}
const KeyGeneration cryptfs_get_keygen() {
return KeyGeneration{get_crypto_type().get_keysize(), true, false};
}
/* 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;
}
/**
* 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;
}
static uint64_t get_fs_size(const char* dev) {
int fd, block_size;
struct ext4_super_block sb;
uint64_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 = (((uint64_t)sb.s_blocks_count_hi << 32) + sb.s_blocks_count_lo) * block_size;
/* return length in sectors */
return len / 512;
}
static void get_crypt_info(std::string* key_loc, std::string* real_blk_device) {
for (const auto& entry : fstab_default) {
if (!entry.fs_mgr_flags.vold_managed &&
(entry.fs_mgr_flags.crypt || entry.fs_mgr_flags.force_crypt ||
entry.fs_mgr_flags.force_fde_or_fbe || entry.fs_mgr_flags.file_encryption)) {
if (key_loc != nullptr) {
*key_loc = entry.key_loc;
}
if (real_blk_device != nullptr) {
*real_blk_device = entry.blk_device;
}
return;
}
}
}
static int get_crypt_ftr_info(char** metadata_fname, off64_t* off) {
static int cached_data = 0;
static uint64_t cached_off = 0;
static char cached_metadata_fname[PROPERTY_VALUE_MAX] = "";
char key_loc[PROPERTY_VALUE_MAX];
char real_blkdev[PROPERTY_VALUE_MAX];
int rc = -1;
if (!cached_data) {
std::string key_loc;
std::string real_blkdev;
get_crypt_info(&key_loc, &real_blkdev);
if (key_loc == KEY_IN_FOOTER) {
if (android::vold::GetBlockDevSize(real_blkdev, &cached_off) == android::OK) {
/* 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.c_str(), sizeof(cached_metadata_fname));
cached_off -= CRYPT_FOOTER_OFFSET;
cached_data = 1;
} else {
SLOGE("Cannot get size of block device %s\n", real_blkdev.c_str());
}
} else {
strlcpy(cached_metadata_fname, key_loc.c_str(), 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;