/*
* Copyright (C) 2013 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.
*/
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <libgen.h>
#include <time.h>
#include <android-base/file.h>
#include <android-base/strings.h>
#include <cutils/properties.h>
#include <logwrap/logwrap.h>
#include "mincrypt/rsa.h"
#include "mincrypt/sha.h"
#include "mincrypt/sha256.h"
#include "fec/io.h"
#include "fs_mgr.h"
#include "fs_mgr_priv.h"
#include "fs_mgr_priv_verity.h"
#define FSTAB_PREFIX "/fstab."
#define VERITY_TABLE_RSA_KEY "/verity_key"
#define VERITY_TABLE_HASH_IDX 8
#define VERITY_TABLE_SALT_IDX 9
#define VERITY_TABLE_OPT_RESTART "restart_on_corruption"
#define VERITY_TABLE_OPT_LOGGING "ignore_corruption"
#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks"
#define VERITY_TABLE_OPT_FEC_FORMAT \
"use_fec_from_device %s fec_start %" PRIu64 " fec_blocks %" PRIu64 \
" fec_roots %u " VERITY_TABLE_OPT_IGNZERO
#define VERITY_TABLE_OPT_FEC_ARGS 9
#define METADATA_MAGIC 0x01564c54
#define METADATA_TAG_MAX_LENGTH 63
#define METADATA_EOD "eod"
#define VERITY_LASTSIG_TAG "verity_lastsig"
#define VERITY_STATE_TAG "verity_state"
#define VERITY_STATE_HEADER 0x83c0ae9d
#define VERITY_STATE_VERSION 1
#define VERITY_KMSG_RESTART "dm-verity device corrupted"
#define VERITY_KMSG_BUFSIZE 1024
#define __STRINGIFY(x) #x
#define STRINGIFY(x) __STRINGIFY(x)
struct verity_state {
uint32_t header;
uint32_t version;
int32_t mode;
};
extern struct fs_info info;
static RSAPublicKey *load_key(const char *path)
{
RSAPublicKey* key = static_cast<RSAPublicKey*>(malloc(sizeof(RSAPublicKey)));
if (!key) {
ERROR("Can't malloc key\n");
return NULL;
}
FILE* f = fopen(path, "r");
if (!f) {
ERROR("Can't open '%s'\n", path);
free(key);
return NULL;
}
if (!fread(key, sizeof(*key), 1, f)) {
ERROR("Could not read key!\n");
fclose(f);
free(key);
return NULL;
}
if (key->len != RSANUMWORDS) {
ERROR("Invalid key length %d\n", key->len);
fclose(f);
free(key);
return NULL;
}
fclose(f);
return key;
}
static int verify_table(const uint8_t *signature, const char *table,
uint32_t table_length)
{
RSAPublicKey *key;
uint8_t hash_buf[SHA256_DIGEST_SIZE];
int retval = -1;
// Hash the table
SHA256_hash((uint8_t*)table, table_length, hash_buf);
// Now get the public key from the keyfile
key = load_key(VERITY_TABLE_RSA_KEY);
if (!key) {
ERROR("Couldn't load verity keys\n");
goto out;
}
// verify the result
if (!RSA_verify(key,
signature,
RSANUMBYTES,
(uint8_t*) hash_buf,
SHA256_DIGEST_SIZE)) {
ERROR("Couldn't verify table\n");
goto out;
}
retval = 0;
out:
free(key);
return retval;
}
static int verify_verity_signature(const struct fec_verity_metadata& verity)
{
if (verify_table(verity.signature, verity.table,
verity.table_length) == 0 ||
verify_table(verity.ecc_signature, verity.table,
verity.table_length) == 0) {
return 0;
}
return -1;
}
static int invalidate_table(char *table, size_t table_length)
{
size_t n = 0;
size_t idx = 0;
size_t cleared = 0;
while (n < table_length) {
if (table[n++] == ' ') {
++idx;
}
if (idx != VERITY_TABLE_HASH_IDX && idx != VERITY_TABLE_SALT_IDX) {
continue;
}
while (n < table_length && table[n] != ' ') {
table[n++] = '0';
}
if (++cleared == 2) {
return 0;
}
}
return -1;
}
static void verity_ioctl_init(struct dm_ioctl *io, const char *name, unsigned flags)
{
memset(io, 0, DM_BUF_SIZE);
io->data_size = DM_BUF_SIZE;
io->data_start = sizeof(struct dm_ioctl);
io->version[0] = 4;
io->version[1] = 0;
io->version[2] = 0;
io->flags = flags | DM_READONLY_FLAG;
if (name) {
strlcpy(io->name, name, sizeof(io->name));
}
}
static int create_verity_device(struct dm_ioctl *io, char *name, int fd)
{
verity_ioctl_init(io, name, 1);
if (ioctl(fd, DM_DEV_CREATE, io)) {
ERROR("Error creating device mapping (%s)", strerror(errno));
return -1;
}
return 0;
}
static int get_verity_device_name(struct dm_ioctl *io, char *name, int fd, char **dev_name)
{
verity_ioctl_init(io, name, 0);
if (ioctl(fd, DM_DEV_STATUS, io)) {
ERROR("Error fetching verity device number (%s)", strerror(errno));
return -1;
}
int dev_num = (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00);
if (asprintf(dev_name, "/dev/block/dm-%u", dev_num) < 0) {
ERROR("Error getting verity block device name (%s)", strerror(errno));
return -1;
}
return 0;
}
struct verity_table_params {
char *table;
int mode;
struct fec_ecc_metadata ecc;
const char *ecc_dev;
};
typedef bool (*format_verity_table_func)(char *buf, const size_t bufsize,
const struct verity_table_params *params);
static bool format_verity_table(char *buf, const size_t bufsize,
const struct verity_table_params *params)
{
const char *mode_flag = NULL;
int res = -1;
if (params->mode == VERITY_MODE_RESTART) {
mode_flag = VERITY_TABLE_OPT_RESTART;
} else if (params->mode == VERITY_MODE_LOGGING) {
mode_flag = VERITY_TABLE_OPT_LOGGING;
}
if (params->ecc.valid) {
if (mode_flag) {
res = snprintf(buf, bufsize,
"%s %u %s " VERITY_TABLE_OPT_FEC_FORMAT,
params->table, 1 + VERITY_TABLE_OPT_FEC_ARGS, mode_flag, params->ecc_dev,
params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots);
} else {
res = snprintf(buf, bufsize,
"%s %u " VERITY_TABLE_OPT_FEC_FORMAT,
params->table, VERITY_TABLE_OPT_FEC_ARGS, params->ecc_dev,
params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots);
}
} else if (mode_flag) {
res = snprintf(buf, bufsize, "%s 2 " VERITY_TABLE_OPT_IGNZERO " %s", params->table,
mode_flag);
} else {
res = snprintf(buf, bufsize, "%s 1 " VERITY_TABLE_OPT_IGNZERO, params->table);
}
if (res < 0 || (size_t)res >= bufsize) {
ERROR("Error building verity table; insufficient buffer size?\n");
return false;
}
return true;
}
static bool format_legacy_verity_table(char *buf, const size_t bufsize,
const struct verity_table_params *params)
{
int res;
if (params->mode == VERITY_MODE_EIO) {
res = strlcpy(buf, params->table, bufsize);
} else {
res = snprintf(buf, bufsize, "%s %d", params->table, params->mode);
}
if (res < 0 || (size_t)res >= bufsize) {
ERROR("Error building verity table; insufficient buffer size?\n");
return false;
}
return true;
}
static int load_verity_table(struct dm_ioctl *io, char *name, uint64_t device_size, int fd,
const struct verity_table_params *params, format_verity_table_func format)
{
char *verity_params;
char *buffer = (char*) io;
size_t bufsize;
verity_ioctl_init(io, name, DM_STATUS_TABLE_FLAG);
struct dm_target_spec *tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)];
// set tgt arguments
io->target_count = 1;
tgt->status = 0;
tgt->sector_start = 0;
tgt->length = device_size / 512;
strcpy(tgt->target_type, "verity");
// build the verity params
verity_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec);
bufsize = DM_BUF_SIZE - (verity_params - buffer);
if (!format(verity_params, bufsize, params)) {
ERROR("Failed to format verity parameters\n");
return -1;
}
INFO("loading verity table: '%s'", verity_params);
// set next target boundary
verity_params += strlen(verity_params) + 1;
verity_params = (char*)(((unsigned long)verity_params + 7) & ~8);
tgt->next = verity_params - buffer;
// send the ioctl to load the verity table
if (ioctl(fd, DM_TABLE_LOAD, io)) {
ERROR("Error loading verity table (%s)\n", strerror(errno));
return -1;
}
return 0;
}
static int resume_verity_table(struct dm_ioctl *io, char *name, int fd)
{
verity_ioctl_init(io, name, 0);
if (ioctl(fd, DM_DEV_SUSPEND, io)) {
ERROR("Error activating verity device (%s)", strerror(errno));
return -1;
}
return 0;
}
static int test_access(char *device) {
int tries = 25;
while (tries--) {
if (!access(device, F_OK) || errno != ENOENT) {
return 0;
}
usleep(40 * 1000);
}
return -1;
}
static int check_verity_restart(const char *fname)
{
char buffer[VERITY_KMSG_BUFSIZE + 1];
int fd;
int rc = 0;
ssize_t size;
struct stat s;
fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
if (errno != ENOENT) {
ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
}
goto out;
}
if (fstat(fd, &s) == -1) {
ERROR("Failed to fstat %s (%s)\n", fname, strerror(errno));
goto out;
}
size = VERITY_KMSG_BUFSIZE;
if (size > s.st_size) {
size = s.st_size;
}
if (lseek(fd, s.st_size - size, SEEK_SET) == -1) {
ERROR("Failed to lseek %jd %s (%s)\n", (intmax_t)(s.st_size - size), fname,
strerror(errno));
goto out;
}
if (!android::base::ReadFully(fd, buffer, size)) {
ERROR("Failed to read %zd bytes from %s (%s)\n", size, fname,
strerror(errno));
goto out;
}
buffer[size] = '\0';
if (strstr(buffer, VERITY_KMSG_RESTART) != NULL) {
rc = 1;
}
out:
if (fd != -1) {
close(fd);
}
return rc;
}
static int was_verity_restart()
{
static const char *files[] = {
"/sys/fs/pstore/console-ramoops",
"/proc/last_kmsg",
NULL
};
int i;
for (i = 0; files[i]; ++i) {
if (check_verity_restart(files[i])) {
return 1;
}
}
return 0;
}
static int metadata_add(FILE *fp, long start, const char *tag,
unsigned int length, off64_t *offset)
{
if (fseek(fp, start, SEEK_SET) < 0 ||
fprintf(fp, "%s %u\n", tag, length) < 0) {
return -1;
}
*offset = ftell(fp);
if (fseek(fp, length, SEEK_CUR) < 0 ||
fprintf(fp, METADATA_EOD " 0\n") < 0) {
return -1;
}
return 0;
}
static int metadata_find(const char *fname, const char *stag,
unsigned int slength, off64_t *offset)
{
FILE *fp = NULL;
char tag[METADATA_TAG_MAX_LENGTH + 1];
int rc = -1;
int n;
long start = 0x4000; /* skip cryptfs metadata area */
uint32_t magic;
unsigned int length = 0;
if (!fname) {
return -1;
}
fp = fopen(fname, "r+");
if (!fp) {
ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
goto out;
}
/* check magic */
if (fseek(fp, start, SEEK_SET) < 0 ||
fread(&magic, sizeof(magic), 1, fp) != 1) {
ERROR("Failed to read magic from %s (%s)\n", fname, strerror(errno));
goto out;
}
if (magic != METADATA_MAGIC) {
magic = METADATA_MAGIC;
if (fseek(fp, start, SEEK_SET) < 0 ||
fwrite(&magic, sizeof(magic), 1, fp) != 1) {
ERROR("Failed to write magic to %s (%s)\n", fname, strerror(errno));
goto out;
}
rc = metadata_add(fp, start + sizeof(magic), stag, slength, offset);
if (rc < 0) {
ERROR("Failed to add metadata to %s: %s\n", fname, strerror(errno));
}
goto out;
}
start += sizeof(magic);
while (1) {
n = fscanf(fp, "%" STRINGIFY(METADATA_TAG_MAX_LENGTH) "s %u\n",
tag, &length);
if (n == 2 && strcmp(tag, METADATA_EOD)) {
/* found a tag */
start = ftell(fp);
if (!strcmp(tag, stag) && length == slength) {
*offset = start;
rc = 0;
goto out;
}
start += length;
if (fseek(fp, length, SEEK_CUR) < 0) {
ERROR("Failed to seek %s (%s)\n", fname, strerror(errno));
goto out;
}
} else {
rc = metadata_add(fp, start, stag, slength, offset);
if (rc < 0) {
ERROR("Failed to write metadata to %s: %s\n", fname,
strerror(errno));
}
goto out;
}
}
out:
if (fp) {
fflush(fp);
fclose(fp);
}
return rc;
}
static int write_verity_state(const char *fname, off64_t offset, int32_t mode)
{
int fd;
int rc = -1;
struct verity_state s = { VERITY_STATE_HEADER, VERITY_STATE_VERSION, mode };
fd = TEMP_FAILURE_RETRY(open(fname, O_WRONLY | O_SYNC | O_CLOEXEC));
if (fd == -1) {
ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(pwrite64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
ERROR("Failed to write %zu bytes to %s to offset %" PRIu64 " (%s)\n",
sizeof(s), fname, offset, strerror(errno));
goto out;
}
rc = 0;
out:
if (fd != -1) {
close(fd);
}
return rc;
}
static int read_verity_state(const char *fname, off64_t offset, int *mode)
{
int fd = -1;
int rc = -1;
struct verity_state s;
fd = TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
ERROR("Failed to open %s (%s)\n", fname, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(pread64(fd, &s, sizeof(s), offset)) != sizeof(s)) {
ERROR("Failed to read %zu bytes from %s offset %" PRIu64 " (%s)\n",
sizeof(s), fname, offset, strerror(errno));
goto out;
}
if (s.header != VERITY_STATE_HEADER) {
/* space allocated, but no state written. write default state */
*mode = VERITY_MODE_DEFAULT;
rc = write_verity_state(fname, offset, *mode);
goto out;
}
if (s.version != VERITY_STATE_VERSION) {
ERROR("Unsupported verity state version (%u)\n", s.version);
goto out;
}
if (s.mode < VERITY_MODE_EIO ||
s.mode > VERITY_MODE_LAST) {
ERROR("Unsupported verity mode (%u)\n", s.mode);
goto out;
}
*mode = s.mode;
rc = 0;
out:
if (fd != -1) {
close(fd);
}
return rc;
}
static int compare_last_signature(struct fstab_rec *fstab, int *match)
{
char tag[METADATA_TAG_MAX_LENGTH + 1];
int fd = -1;
int rc = -1;
off64_t offset = 0;
struct fec_handle *f = NULL;
struct fec_verity_metadata verity;
uint8_t curr[SHA256_DIGEST_SIZE];
uint8_t prev[SHA256_DIGEST_SIZE];
*match = 1;
if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE,
FEC_DEFAULT_ROOTS) == -1) {
ERROR("Failed to open '%s' (%s)\n", fstab->blk_device,
strerror(errno));
return rc;
}
// read verity metadata
if (fec_verity_get_metadata(f, &verity) == -1) {
ERROR("Failed to get verity metadata '%s' (%s)\n", fstab->blk_device,
strerror(errno));
goto out;
}
SHA256_hash(verity.signature, RSANUMBYTES, curr);
if (snprintf(tag, sizeof(tag), VERITY_LASTSIG_TAG "_%s",
basename(fstab->mount_point)) >= (int)sizeof(tag)) {
ERROR("Metadata tag name too long for %s\n", fstab->mount_point);
goto out;
}
if (metadata_find(fstab->verity_loc, tag, SHA256_DIGEST_SIZE,
&offset) < 0) {
goto out;
}
fd = TEMP_FAILURE_RETRY(open(fstab->verity_loc, O_RDWR | O_SYNC | O_CLOEXEC));
if (fd == -1) {
ERROR("Failed to open %s: %s\n", fstab->verity_loc, strerror(errno));
goto out;
}
if (TEMP_FAILURE_RETRY(pread64(fd, prev, sizeof(prev),
offset)) != sizeof(prev)) {
ERROR("Failed to read %zu bytes from %s offset %" PRIu64 " (%s)\n",
sizeof(prev), fstab->verity_loc, offset, strerror(errno));
goto out;
}
*match = !memcmp(curr, prev, SHA256_DIGEST_SIZE);
if (!*match) {
/* update current signature hash */
if (TEMP_FAILURE_RETRY(pwrite64(fd, curr, sizeof(curr),
offset)) != sizeof(curr)) {
ERROR("Failed to write %zu bytes to %s offset %" PRIu64 " (%s)\n",
sizeof(curr), fstab->verity_loc, offset, strerror(errno));
goto out;
}
}
rc = 0;
out:
fec_close(f);
return rc;
}
static int get_verity_state_offset(struct fstab_rec *fstab, off64_t *offset)
{
char tag[METADATA_TAG_MAX_LENGTH + 1];
if (snprintf(tag, sizeof(tag), VERITY_STATE_TAG "_%s",
basename(fstab->mount_point)) >= (int)sizeof(tag)) {
ERROR("Metadata tag name too long for %s\n", fstab->mount_point);
return -1;
}
return metadata_find(fstab->verity_loc, tag, sizeof(struct verity_state),
offset);
}
static int load_verity_state(struct fstab_rec *fstab, int *mode)
{
char propbuf[PROPERTY_VALUE_MAX];
int match = 0;
off64_t offset = 0;
/* unless otherwise specified, use EIO mode */
*mode = VERITY_MODE_EIO;
/* use the kernel parameter if set */
property_get("ro.boot.veritymode", propbuf, "");
if (*propbuf != '\0') {
if (!strcmp(propbuf, "enforcing")) {
*mode = VERITY_MODE_DEFAULT;
}
return 0;
}
if (get_verity_state_offset(fstab, &offset) < 0) {
/* fall back to stateless behavior */
return 0;
}
if (was_verity_restart()) {
/* device was restarted after dm-verity detected a corrupted
* block, so use EIO mode */
return write_verity_state(fstab->verity_loc, offset, *mode);
}
if (!compare_last_signature(fstab, &match) && !match) {
/* partition has been reflashed, reset dm-verity state */
*mode = VERITY_MODE_DEFAULT;
return write_verity_state(fstab->verity_loc, offset, *mode);
}
return read_verity_state(fstab->verity_loc, offset, mode);
}
int fs_mgr_load_verity_state(int *mode)
{
char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
char propbuf[PROPERTY_VALUE_MAX];
int rc = -1;
int i;
int current;
struct fstab *fstab = NULL;
/* return the default mode, unless any of the verified partitions are in
* logging mode, in which case return that */
*mode = VERITY_MODE_DEFAULT;
property_get("ro.hardware", propbuf, "");
snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
fstab = fs_mgr_read_fstab(fstab_filename);
if (!fstab) {
ERROR("Failed to read %s\n", fstab_filename);
goto out;
}
for (i = 0; i < fstab->num_entries; i++) {
if (!fs_mgr_is_verified(&fstab->recs[i])) {
continue;
}
rc = load_verity_state(&fstab->recs[i], ¤t);
if (rc < 0) {
continue;
}
if (current != VERITY_MODE_DEFAULT) {
*mode = current;
break;
}
}
rc = 0;
out:
if (fstab) {
fs_mgr_free_fstab(fstab);
}
return rc;
}
int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback)
{
alignas(dm_ioctl) char buffer[DM_BUF_SIZE];
bool system_root = false;
char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
const char *mount_point;
char propbuf[PROPERTY_VALUE_MAX];
char *status;
int fd = -1;
int i;
int mode;
int rc = -1;
struct dm_ioctl *io = (struct dm_ioctl *) buffer;
struct fstab *fstab = NULL;
if (!callback) {
return -1;
}
if (fs_mgr_load_verity_state(&mode) == -1) {
return -1;
}
fd = TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR | O_CLOEXEC));
if (fd == -1) {
ERROR("Error opening device mapper (%s)\n", strerror(errno));
goto out;
}
property_get("ro.hardware", propbuf, "");
snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX"%s", propbuf);
property_get("ro.build.system_root_image", propbuf, "");
system_root = !strcmp(propbuf, "true");
fstab = fs_mgr_read_fstab(fstab_filename);
if (!fstab) {
ERROR("Failed to read %s\n", fstab_filename);
goto out;
}
for (i = 0; i < fstab->num_entries; i++) {
if (!fs_mgr_is_verified(&fstab->recs[i])) {
continue;
}
if (system_root && !strcmp(fstab->recs[i].mount_point, "/")) {
mount_point = "system";
} else {
mount_point = basename(fstab->recs[i].mount_point);
}
verity_ioctl_init(io, mount_point, 0);
if (ioctl(fd, DM_TABLE_STATUS, io)) {
ERROR("Failed to query DM_TABLE_STATUS for %s (%s)\n", mount_point,
strerror(errno));
continue;
}
status = &buffer[io->data_start + sizeof(struct dm_target_spec)];
if (*status == 'C' || *status == 'V') {
callback(&fstab->recs[i], mount_point, mode, *status);
}
}
rc = 0;
out:
if (fstab) {
fs_mgr_free_fstab(fstab);
}
if (fd) {
close(fd);
}
return rc;
}
static void update_verity_table_blk_device(char *blk_device, char **table)
{
std::string result, word;
auto tokens = android::base::Split(*table, " ");
for (const auto token : tokens) {
if (android::base::StartsWith(token, "/dev/block/") &&
android::base::StartsWith(blk_device, token.c_str())) {
word = blk_device;
} else {
word = token;
}
if (result.empty()) {
result = word;
} else {
result += " " + word;
}
}
if (result.empty()) {
return;
}
free(*table);
*table = strdup(result.c_str());
}
int fs_mgr_setup_verity(struct fstab_rec *fstab)
{
int retval = FS_MGR_SETUP_VERITY_FAIL;
int fd = -1;
char *verity_blk_name = NULL;
struct fec_handle *f = NULL;
struct fec_verity_metadata verity;
struct verity_table_params params = { .table = NULL };
alignas(dm_ioctl) char buffer[DM_BUF_SIZE];
struct dm_ioctl *io = (struct dm_ioctl *) buffer;
char *mount_point = basename(fstab->mount_point);
if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE,
FEC_DEFAULT_ROOTS) < 0) {
ERROR("Failed to open '%s' (%s)\n", fstab->blk_device,
strerror(errno));
return retval;
}
// read verity metadata
if (fec_verity_get_metadata(f, &verity) < 0) {
ERROR("Failed to get verity metadata '%s' (%s)\n", fstab->blk_device,
strerror(errno));
goto out;
}
#ifdef ALLOW_ADBD_DISABLE_VERITY
if (verity.disabled) {
retval = FS_MGR_SETUP_VERITY_DISABLED;
INFO("Attempt to cleanly disable verity - only works in USERDEBUG\n");
goto out;
}
#endif
// read ecc metadata
if (fec_ecc_get_metadata(f, ¶ms.ecc) < 0) {
params.ecc.valid = false;
}
params.ecc_dev = fstab->blk_device;
// get the device mapper fd
if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) {
ERROR("Error opening device mapper (%s)\n", strerror(errno));
goto out;
}
// create the device
if (create_verity_device(io, mount_point, fd) < 0) {
ERROR("Couldn't create verity device!\n");
goto out;
}
// get the name of the device file
if (get_verity_device_name(io, mount_point, fd, &verity_blk_name) < 0) {
ERROR("Couldn't get verity device number!\n");
goto out;
}
if (load_verity_state(fstab, ¶ms.mode) < 0) {
/* if accessing or updating the state failed, switch to the default
* safe mode. This makes sure the device won't end up in an endless
* restart loop, and no corrupted data will be exposed to userspace
* without a warning. */
params.mode = VERITY_MODE_EIO;
}
if (!verity.table) {
goto out;
}
params.table = strdup(verity.table);
if (!params.table) {
goto out;
}
// verify the signature on the table
if (verify_verity_signature(verity) < 0) {
if (params.mode == VERITY_MODE_LOGGING) {
// the user has been warned, allow mounting without dm-verity
retval = FS_MGR_SETUP_VERITY_SUCCESS;
goto out;
}
// invalidate root hash and salt to trigger device-specific recovery
if (invalidate_table(params.table, verity.table_length) < 0) {
goto out;
}
}
INFO("Enabling dm-verity for %s (mode %d)\n", mount_point, params.mode);
if (fstab->fs_mgr_flags & MF_SLOTSELECT) {
// Update the verity params using the actual block device path
update_verity_table_blk_device(fstab->blk_device, ¶ms.table);
}
// load the verity mapping table
if (load_verity_table(io, mount_point, verity.data_size, fd, ¶ms,
format_verity_table) == 0) {
goto loaded;
}
if (params.ecc.valid) {
// kernel may not support error correction, try without
INFO("Disabling error correction for %s\n", mount_point);
params.ecc.valid = false;
if (load_verity_table(io, mount_point, verity.data_size, fd, ¶ms,
format_verity_table) == 0) {
goto loaded;
}
}
// try the legacy format for backwards compatibility
if (load_verity_table(io, mount_point, verity.data_size, fd, ¶ms,
format_legacy_verity_table) == 0) {
goto loaded;
}
if (params.mode != VERITY_MODE_EIO) {
// as a last resort, EIO mode should always be supported
INFO("Falling back to EIO mode for %s\n", mount_point);
params.mode = VERITY_MODE_EIO;
if (load_verity_table(io, mount_point, verity.data_size, fd, ¶ms,
format_legacy_verity_table) == 0) {
goto loaded;
}
}
ERROR("Failed to load verity table for %s\n", mount_point);
goto out;
loaded:
// activate the device
if (resume_verity_table(io, mount_point, fd) < 0) {
goto out;
}
// mark the underlying block device as read-only
fs_mgr_set_blk_ro(fstab->blk_device);
// assign the new verity block device as the block device
free(fstab->blk_device);
fstab->blk_device = verity_blk_name;
verity_blk_name = 0;
// make sure we've set everything up properly
if (test_access(fstab->blk_device) < 0) {
goto out;
}
retval = FS_MGR_SETUP_VERITY_SUCCESS;
out:
if (fd != -1) {
close(fd);
}
fec_close(f);
free(params.table);
free(verity_blk_name);
return retval;
}