blob: 52a7f747307b58a0cbd01b92f51a219e61869ee6 [file] [log] [blame]
/*
* Copyright (C) 2019 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 <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <libavb_user/libavb_user.h>
#include <stdarg.h>
#include <stdio.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <unistd.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include <fs_mgr.h>
#include <fs_mgr_overlayfs.h>
#include <fstab/fstab.h>
#include <log/log_properties.h>
#include "fec/io.h"
#ifdef ALLOW_DISABLE_VERITY
static const bool kAllowDisableVerity = true;
#else
static const bool kAllowDisableVerity = false;
#endif
using android::base::unique_fd;
static void suggest_run_adb_root() {
if (getuid() != 0) printf("Maybe run adb root?\n");
}
static bool make_block_device_writable(const std::string& dev) {
unique_fd fd(open(dev.c_str(), O_RDONLY | O_CLOEXEC));
if (fd == -1) {
return false;
}
int OFF = 0;
bool result = (ioctl(fd.get(), BLKROSET, &OFF) != -1);
return result;
}
/* Turn verity on/off */
static bool set_verity_enabled_state(const char* block_device, const char* mount_point,
bool enable) {
if (!make_block_device_writable(block_device)) {
printf("Could not make block device %s writable (%s).\n", block_device, strerror(errno));
return false;
}
fec::io fh(block_device, O_RDWR);
if (!fh) {
printf("Could not open block device %s (%s).\n", block_device, strerror(errno));
suggest_run_adb_root();
return false;
}
fec_verity_metadata metadata;
if (!fh.get_verity_metadata(metadata)) {
printf("Couldn't find verity metadata!\n");
return false;
}
if (!enable && metadata.disabled) {
printf("Verity already disabled on %s\n", mount_point);
return false;
}
if (enable && !metadata.disabled) {
printf("Verity already enabled on %s\n", mount_point);
return false;
}
if (!fh.set_verity_status(enable)) {
printf("Could not set verity %s flag on device %s with error %s\n",
enable ? "enabled" : "disabled", block_device, strerror(errno));
return false;
}
auto change = false;
errno = 0;
if (enable ? fs_mgr_overlayfs_teardown(mount_point, &change)
: fs_mgr_overlayfs_setup(nullptr, mount_point, &change)) {
if (change) {
printf("%s overlayfs for %s\n", enable ? "disabling" : "using", mount_point);
}
} else if (errno) {
int expected_errno = enable ? EBUSY : ENOENT;
if (errno != expected_errno) {
printf("Overlayfs %s for %s failed with error %s\n", enable ? "teardown" : "setup",
mount_point, strerror(errno));
}
}
printf("Verity %s on %s\n", enable ? "enabled" : "disabled", mount_point);
return true;
}
/* Helper function to get A/B suffix, if any. If the device isn't
* using A/B the empty string is returned. Otherwise either "_a",
* "_b", ... is returned.
*/
static std::string get_ab_suffix() {
return android::base::GetProperty("ro.boot.slot_suffix", "");
}
static bool is_avb_device_locked() {
return android::base::GetProperty("ro.boot.vbmeta.device_state", "") == "locked";
}
static bool overlayfs_setup(bool enable) {
auto change = false;
errno = 0;
if (enable ? fs_mgr_overlayfs_teardown(nullptr, &change)
: fs_mgr_overlayfs_setup(nullptr, nullptr, &change)) {
if (change) {
printf("%s overlayfs\n", enable ? "disabling" : "using");
}
} else if (errno) {
printf("Overlayfs %s failed with error %s\n", enable ? "teardown" : "setup", strerror(errno));
suggest_run_adb_root();
}
return change;
}
/* Use AVB to turn verity on/off */
static bool set_avb_verity_enabled_state(AvbOps* ops, bool enable_verity) {
std::string ab_suffix = get_ab_suffix();
bool verity_enabled;
if (is_avb_device_locked()) {
printf("Device is locked. Please unlock the device first\n");
return false;
}
if (!avb_user_verity_get(ops, ab_suffix.c_str(), &verity_enabled)) {
printf("Error getting verity state. Try adb root first?\n");
return false;
}
if ((verity_enabled && enable_verity) || (!verity_enabled && !enable_verity)) {
printf("verity is already %s\n", verity_enabled ? "enabled" : "disabled");
return false;
}
if (!avb_user_verity_set(ops, ab_suffix.c_str(), enable_verity)) {
printf("Error setting verity\n");
return false;
}
overlayfs_setup(enable_verity);
printf("Successfully %s verity\n", enable_verity ? "enabled" : "disabled");
return true;
}
int main(int argc, char* argv[]) {
if (argc == 0) {
LOG(FATAL) << "set-verity-state called with empty argv";
}
std::optional<bool> enable_opt;
std::string procname = android::base::Basename(argv[0]);
if (procname == "enable-verity") {
enable_opt = true;
} else if (procname == "disable-verity") {
enable_opt = false;
}
if (!enable_opt.has_value()) {
if (argc != 2) {
printf("usage: %s [1|0]\n", argv[0]);
return 1;
}
if (strcmp(argv[1], "1") == 0) {
enable_opt = true;
} else if (strcmp(argv[1], "0") == 0) {
enable_opt = false;
} else {
printf("usage: %s [1|0]\n", argv[0]);
return 1;
}
}
bool enable = enable_opt.value();
bool any_changed = false;
// Figure out if we're using VB1.0 or VB2.0 (aka AVB) - by
// contract, androidboot.vbmeta.digest is set by the bootloader
// when using AVB).
bool using_avb = !android::base::GetProperty("ro.boot.vbmeta.digest", "").empty();
// If using AVB, dm-verity is used on any build so we want it to
// be possible to disable/enable on any build (except USER). For
// VB1.0 dm-verity is only enabled on certain builds.
if (!using_avb) {
if (!kAllowDisableVerity) {
printf("%s only works for userdebug builds\n", argv[0]);
}
if (!android::base::GetBoolProperty("ro.secure", false)) {
overlayfs_setup(enable);
printf("verity not enabled - ENG build\n");
return 0;
}
}
// Should never be possible to disable dm-verity on a USER build
// regardless of using AVB or VB1.0.
if (!__android_log_is_debuggable()) {
printf("verity cannot be disabled/enabled - USER build\n");
return 0;
}
if (using_avb) {
// Yep, the system is using AVB.
AvbOps* ops = avb_ops_user_new();
if (ops == nullptr) {
printf("Error getting AVB ops\n");
return 1;
}
if (set_avb_verity_enabled_state(ops, enable)) {
any_changed = true;
}
avb_ops_user_free(ops);
}
if (!any_changed) any_changed = overlayfs_setup(enable);
if (any_changed) {
printf("Now reboot your device for settings to take effect\n");
}
return 0;
}