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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 <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/dm-ioctl.h>
#include <libgen.h>
#include <stdlib.h>
#include <sys/param.h>
#include <string.h>
#include <sys/mount.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <errno.h>
#include <ext4.h>
#include <linux/kdev_t.h>
#include <fs_mgr.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"
#define UNUSED __attribute__((unused))
#define DM_CRYPT_BUF_SIZE 4096
#define DATA_MNT_POINT "/data"
#define HASH_COUNT 2000
#define KEY_LEN_BYTES 16
#define IV_LEN_BYTES 16
#define KEY_IN_FOOTER "footer"
#define EXT4_FS 1
#define FAT_FS 2
#define TABLE_LOAD_RETRIES 10
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;
extern struct fstab *fstab;
static void cryptfs_reboot(int recovery)
{
if (recovery) {
property_set(ANDROID_RB_PROPERTY, "reboot,recovery");
} else {
property_set(ANDROID_RB_PROPERTY, "reboot");
}
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) {
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)) {
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)) < 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);
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];
unsigned int nr_sec;
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)) < 0) {
SLOGE("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 {
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 nr_sec, 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, 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");
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;
}
if ((crypt_ftr->major_version == 1) && (crypt_ftr->minor_version)) {
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 ((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 nr_sec, 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)) < 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);
}
/* 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 = 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.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);
if (fd < 0) {
SLOGE("Cannot open %s metadata file", fname);
return -1;
}
if (persist_data == NULL) {
pdata = 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 */
persist_data = pdata;
close(fd);
return 0;
err2:
free(pdata);
err:
close(fd);
return -1;
}
static int save_persistent_data(void)
{
struct crypt_mnt_ftr crypt_ftr;
struct crypt_persist_data *pdata;
char *fname;
off64_t write_offset;
off64_t erase_offset;
int found = 0;
int fd;
int ret;
if (persist_data == NULL) {
SLOGE("No persistent data to save");
return -1;
}
if(get_crypt_ftr_and_key(&crypt_ftr)) {
return -1;
}
if ((crypt_ftr.major_version != 1) || (crypt_ftr.minor_version != 1)) {
SLOGE("Crypt_ftr version doesn't support persistent data");
return -1;
}
ret = validate_persistent_data_storage(&crypt_ftr);
if (ret) {
return -1;
}
if (get_crypt_ftr_info(&fname, NULL)) {
return -1;
}
fd = open(fname, O_RDWR);
if (fd < 0) {
SLOGE("Cannot open %s metadata file", fname);
return -1;
}
pdata = malloc(crypt_ftr.persist_data_size);
if (pdata == NULL) {
SLOGE("Cannot allocate persistant data");
goto err;
}
if (lseek64(fd, crypt_ftr.persist_data_offset[0], 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 before save");
goto err2;
}
if (pdata->persist_magic == PERSIST_DATA_MAGIC) {
/* The first copy is the curent valid copy, so write to
* the second copy and erase this one */
write_offset = crypt_ftr.persist_data_offset[1];
erase_offset = crypt_ftr.persist_data_offset[0];
} else {
/* The second copy must be the valid copy, so write to
* the first copy, and erase the second */
write_offset = crypt_ftr.persist_data_offset[0];
erase_offset = crypt_ftr.persist_data_offset[1];
}
/* Write the new copy first, if successful, then erase the old copy */
if (lseek(fd, write_offset, SEEK_SET) < 0) {
SLOGE("Cannot seek to write persistent data");
goto err2;
}
if (unix_write(fd, persist_data, crypt_ftr.persist_data_size) ==
(int) crypt_ftr.persist_data_size) {
if (lseek(fd, erase_offset, SEEK_SET) < 0) {
SLOGE("Cannot seek to erase previous persistent data");
goto err2;
}
fsync(fd);
memset(pdata, 0, crypt_ftr.persist_data_size);
if (unix_write(fd, pdata, crypt_ftr.persist_data_size) !=
(int) crypt_ftr.persist_data_size) {
SLOGE("Cannot write to erase previous persistent data");
goto err2;
}
fsync(fd);
} else {
SLOGE("Cannot write to save persistent data");
goto err2;
}
/* Success */
free(pdata);
close(fd);
return 0;
err2:
free(pdata);
err:
close(fd);
return -1;
}
/* Convert a binary key of specified length into an ascii hex string equivalent,
* without the leading 0x and with null termination
*/
void convert_key_to_hex_ascii(unsigned char *master_key, unsigned int keysize,
char *master_key_ascii)
{
unsigned int i, a;
unsigned char nibble;
for (i=0, a=0; i<keysize; i++, a+=2) {
/* For each byte, write out two ascii hex digits */
nibble = (master_key[i] >> 4) & 0xf;
master_key_ascii[a] = nibble + (nibble > 9 ? 0x37 : 0x30);
nibble = master_key[i] & 0xf;
master_key_ascii[a+1] = nibble + (nibble > 9 ? 0x37 : 0x30);
}
/* Add the null termination */
master_key_ascii[a] = '\0';
}
static int load_crypto_mapping_table(struct crypt_mnt_ftr *crypt_ftr, unsigned char *master_key,
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;
strcpy(tgt->target_type, "crypt");
crypt_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
convert_key_to_hex_ascii(master_key, crypt_ftr->keysize, master_key_ascii);
sprintf(crypt_params, "%s %s 0 %s 0 %s", crypt_ftr->crypto_type_name,
master_key_ascii, 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;
}
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 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) {
if (! strcmp(v->name, "crypt")) {
/* 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, unsigned char *master_key,
char *real_blk_name, char *crypto_blk_name, const char *name)
{
char buffer[DM_CRYPT_BUF_SIZE];
char master_key_ascii[129]; /* Large enough to hold 512 bit key and null */
char *crypt_params;
struct dm_ioctl *io;
struct dm_target_spec *tgt;
unsigned int minor;
int fd;
int i;
int retval = -1;
int version[3];
char *extra_params;
int load_count;
if ((fd = open("/dev/device-mapper", O_RDWR)) < 0 ) {
SLOGE("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)) {
SLOGE("Cannot create dm-crypt device\n");
goto errout;
}
/* Get the device status, in particular, the name of it's device file */
ioctl_init(io, DM_CRYPT_BUF_SIZE, name, 0);
if (ioctl(fd, DM_DEV_STATUS, io)) {
SLOGE("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);
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";
SLOGI("Enabling support for allow_discards in dmcrypt.\n");
}
}
load_count = load_crypto_mapping_table(crypt_ftr, master_key, real_blk_name, name,
fd, extra_params);
if (load_count < 0) {
SLOGE("Cannot load dm-crypt mapping table.\n");
goto errout;
} else if (load_count > 1) {
SLOGI("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)) {
SLOGE("Cannot resume the dm-crypt device\n");
goto errout;
}
/* We made it here with no errors. Woot! */
retval = 0;
errout:
close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */
return retval;
}
static int delete_crypto_blk_dev(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 ) {
SLOGE("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)) {
SLOGE("Cannot remove dm-crypt device\n");
goto errout;
}
/* We made it here with no errors. Woot! */
retval = 0;
errout:
close(fd); /* If fd is <0 from a failed open call, it's safe to just ignore the close error */
return retval;
}
static void pbkdf2(char *passwd, unsigned char *salt, unsigned char *ikey, void *params UNUSED) {
/* Turn the password into a key and IV that can decrypt the master key */
PKCS5_PBKDF2_HMAC_SHA1(passwd, strlen(passwd), salt, SALT_LEN,
HASH_COUNT, KEY_LEN_BYTES+IV_LEN_BYTES, ikey);
}
static void scrypt(char *passwd, unsigned char *salt, unsigned char *ikey, void *params) {
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 */
crypto_scrypt((unsigned char *) passwd, strlen(passwd), salt, SALT_LEN, N, r, p, ikey,
KEY_LEN_BYTES + IV_LEN_BYTES);
}
static int encrypt_master_key(char *passwd, unsigned char *salt,
unsigned char *decrypted_master_key,
unsigned char *encrypted_master_key,
struct crypt_mnt_ftr *crypt_ftr)
{
unsigned char ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */
EVP_CIPHER_CTX e_ctx;
int encrypted_len, final_len;
/* Turn the password into a key and IV that can decrypt the master key */
get_device_scrypt_params(crypt_ftr);
scrypt(passwd, salt, ikey, crypt_ftr);
/* Initialize the decryption engine */
if (! EVP_EncryptInit(&e_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptInit failed\n");
return -1;
}
EVP_CIPHER_CTX_set_padding(&e_ctx, 0); /* Turn off padding as our data is block aligned */
/* Encrypt the master key */
if (! EVP_EncryptUpdate(&e_ctx, encrypted_master_key, &encrypted_len,
decrypted_master_key, KEY_LEN_BYTES)) {
SLOGE("EVP_EncryptUpdate failed\n");
return -1;
}
if (! EVP_EncryptFinal(&e_ctx, encrypted_master_key + encrypted_len, &final_len)) {
SLOGE("EVP_EncryptFinal failed\n");
return -1;
}
if (encrypted_len + final_len != KEY_LEN_BYTES) {
SLOGE("EVP_Encryption length check failed with %d, %d bytes\n", encrypted_len, final_len);
return -1;
} else {
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 ikey[32+32] = { 0 }; /* Big enough to hold a 256 bit key and 256 bit IV */
EVP_CIPHER_CTX d_ctx;
int decrypted_len, final_len;
/* Turn the password into a key and IV that can decrypt the master key */
kdf(passwd, salt, ikey, kdf_params);
/* Initialize the decryption engine */
if (! EVP_DecryptInit(&d_ctx, EVP_aes_128_cbc(), ikey, ikey+KEY_LEN_BYTES)) {
return -1;
}
EVP_CIPHER_CTX_set_padding(&d_ctx, 0); /* Turn off padding as our data is block aligned */
/* Decrypt the master key */
if (! EVP_DecryptUpdate(&d_ctx, decrypted_master_key, &decrypted_len,
encrypted_master_key, KEY_LEN_BYTES)) {
return -1;
}
if (! EVP_DecryptFinal(&d_ctx, decrypted_master_key + decrypted_len, &final_len)) {
return -1;
}
if (decrypted_len + final_len != KEY_LEN_BYTES) {
return -1;
} else {
return 0;
}
}
static void get_kdf_func(struct crypt_mnt_ftr *ftr, kdf_func *kdf, void** kdf_params)
{
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)
{
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);
if (ret != 0) {
SLOGW("failure decrypting master key");
}
return ret;
}
static int create_encrypted_random_key(char *passwd, unsigned char *master_key, unsigned char *salt,
struct crypt_mnt_ftr *crypt_ftr) {
int fd;
unsigned char key_buf[KEY_LEN_BYTES];
EVP_CIPHER_CTX e_ctx;
int encrypted_len, final_len;
/* Get some random bits for a key */
fd = open("/dev/urandom", O_RDONLY);
read(fd, key_buf, sizeof(key_buf));