293 lines
10 KiB
C++
293 lines
10 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "MetadataCrypt.h"
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#include "KeyBuffer.h"
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#include <algorithm>
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#include <string>
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#include <thread>
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#include <vector>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <linux/dm-ioctl.h>
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#include <android-base/file.h>
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#include <android-base/logging.h>
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#include <android-base/properties.h>
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#include <android-base/unique_fd.h>
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#include <cutils/fs.h>
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#include <fs_mgr.h>
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#include "Checkpoint.h"
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#include "EncryptInplace.h"
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#include "KeyStorage.h"
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#include "KeyUtil.h"
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#include "Keymaster.h"
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#include "Utils.h"
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#include "VoldUtil.h"
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#define DM_CRYPT_BUF_SIZE 4096
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#define TABLE_LOAD_RETRIES 10
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#define DEFAULT_KEY_TARGET_TYPE "default-key"
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using android::fs_mgr::FstabEntry;
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using android::fs_mgr::GetEntryForMountPoint;
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using android::vold::KeyBuffer;
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static const std::string kDmNameUserdata = "userdata";
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static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
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static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
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static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
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// fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
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// partitions in the fsck domain.
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if (setexeccon(android::vold::sFsckContext)) {
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PLOG(ERROR) << "Failed to setexeccon";
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return false;
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}
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auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
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const_cast<char*>(blk_device), nullptr,
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android::vold::cp_needsCheckpoint());
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if (setexeccon(nullptr)) {
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PLOG(ERROR) << "Failed to clear setexeccon";
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return false;
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}
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if (mount_rc != 0) {
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LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc;
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return false;
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}
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LOG(DEBUG) << "Mounted " << mount_point;
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return true;
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}
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namespace android {
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namespace vold {
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// Note: It is possible to orphan a key if it is removed before deleting
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// Update this once keymaster APIs change, and we have a proper commit.
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static void commit_key(const std::string& dir) {
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while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
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LOG(ERROR) << "Wait for boot timed out";
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}
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Keymaster keymaster;
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auto keyPath = dir + "/" + kFn_keymaster_key_blob;
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auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
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std::string key;
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if (!android::base::ReadFileToString(keyPath, &key)) {
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LOG(ERROR) << "Failed to read old key: " << dir;
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return;
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}
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if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
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PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
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return;
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}
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if (!keymaster.deleteKey(key)) {
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LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
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}
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LOG(INFO) << "Old Key deleted: " << dir;
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}
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static bool read_key(const FstabEntry& data_rec, bool create_if_absent, KeyBuffer* key) {
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if (data_rec.key_dir.empty()) {
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LOG(ERROR) << "Failed to get key_dir";
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return false;
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}
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std::string key_dir = data_rec.key_dir;
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std::string sKey;
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auto dir = key_dir + "/key";
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LOG(DEBUG) << "key_dir/key: " << dir;
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if (fs_mkdirs(dir.c_str(), 0700)) {
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PLOG(ERROR) << "Creating directories: " << dir;
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return false;
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}
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auto temp = key_dir + "/tmp";
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auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
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/* If we have a leftover upgraded key, delete it.
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* We either failed an update and must return to the old key,
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* or we rebooted before commiting the keys in a freak accident.
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* Either way, we can re-upgrade the key if we need to.
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*/
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Keymaster keymaster;
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if (pathExists(newKeyPath)) {
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if (!android::base::ReadFileToString(newKeyPath, &sKey))
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LOG(ERROR) << "Failed to read old key: " << dir;
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else if (!keymaster.deleteKey(sKey))
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LOG(ERROR) << "Old key deletion failed, continuing anyway: " << dir;
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else
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unlink(newKeyPath.c_str());
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}
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bool needs_cp = cp_needsCheckpoint();
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if (!android::vold::retrieveKey(create_if_absent, dir, temp, key, needs_cp)) return false;
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if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
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return true;
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}
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} // namespace vold
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} // namespace android
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static KeyBuffer default_key_params(const std::string& real_blkdev, const KeyBuffer& key) {
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KeyBuffer hex_key;
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if (android::vold::StrToHex(key, hex_key) != android::OK) {
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LOG(ERROR) << "Failed to turn key to hex";
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return KeyBuffer();
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}
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auto res = KeyBuffer() + "AES-256-XTS " + hex_key + " " + real_blkdev.c_str() + " 0";
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return res;
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}
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static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
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if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {
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PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
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return false;
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}
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return true;
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}
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static struct dm_ioctl* dm_ioctl_init(char* buffer, size_t buffer_size, const std::string& dm_name) {
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if (buffer_size < sizeof(dm_ioctl)) {
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LOG(ERROR) << "dm_ioctl buffer too small";
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return nullptr;
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}
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memset(buffer, 0, buffer_size);
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struct dm_ioctl* io = (struct dm_ioctl*)buffer;
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io->data_size = buffer_size;
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io->data_start = sizeof(struct dm_ioctl);
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io->version[0] = 4;
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io->version[1] = 0;
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io->version[2] = 0;
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io->flags = 0;
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dm_name.copy(io->name, sizeof(io->name));
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return io;
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}
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static bool create_crypto_blk_dev(const std::string& dm_name, uint64_t nr_sec,
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const std::string& target_type, const KeyBuffer& crypt_params,
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std::string* crypto_blkdev) {
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android::base::unique_fd dm_fd(
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TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR | O_CLOEXEC, 0)));
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if (dm_fd == -1) {
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PLOG(ERROR) << "Cannot open device-mapper";
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return false;
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}
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alignas(struct dm_ioctl) char buffer[DM_CRYPT_BUF_SIZE];
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auto io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
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if (!io || ioctl(dm_fd.get(), DM_DEV_CREATE, io) != 0) {
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PLOG(ERROR) << "Cannot create dm-crypt device " << dm_name;
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return false;
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}
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// Get the device status, in particular, the name of its device file
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io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
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if (ioctl(dm_fd.get(), DM_DEV_STATUS, io) != 0) {
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PLOG(ERROR) << "Cannot retrieve dm-crypt device status " << dm_name;
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return false;
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}
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*crypto_blkdev = std::string() + "/dev/block/dm-" +
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std::to_string((io->dev & 0xff) | ((io->dev >> 12) & 0xfff00));
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io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
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size_t paramix = io->data_start + sizeof(struct dm_target_spec);
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size_t nullix = paramix + crypt_params.size();
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size_t endix = (nullix + 1 + 7) & 8; // Add room for \0 and align to 8 byte boundary
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if (endix > sizeof(buffer)) {
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LOG(ERROR) << "crypt_params too big for DM_CRYPT_BUF_SIZE";
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return false;
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}
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io->target_count = 1;
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auto tgt = (struct dm_target_spec*)(buffer + io->data_start);
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tgt->status = 0;
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tgt->sector_start = 0;
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tgt->length = nr_sec;
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target_type.copy(tgt->target_type, sizeof(tgt->target_type));
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memcpy(buffer + paramix, crypt_params.data(),
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std::min(crypt_params.size(), sizeof(buffer) - paramix));
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buffer[nullix] = '\0';
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tgt->next = endix;
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for (int i = 0;; i++) {
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if (ioctl(dm_fd.get(), DM_TABLE_LOAD, io) == 0) {
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break;
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}
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if (i + 1 >= TABLE_LOAD_RETRIES) {
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PLOG(ERROR) << "DM_TABLE_LOAD ioctl failed";
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return false;
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}
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PLOG(INFO) << "DM_TABLE_LOAD ioctl failed, retrying";
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usleep(500000);
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}
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// Resume this device to activate it
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io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
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if (ioctl(dm_fd.get(), DM_DEV_SUSPEND, io)) {
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PLOG(ERROR) << "Cannot resume dm-crypt device " << dm_name;
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return false;
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}
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return true;
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}
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bool fscrypt_mount_metadata_encrypted(const std::string& mount_point, bool needs_encrypt) {
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LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
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auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
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if (encrypted_state != "") {
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LOG(DEBUG) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
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return false;
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}
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auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
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if (!data_rec) {
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LOG(ERROR) << "Failed to get data_rec";
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return false;
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}
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KeyBuffer key;
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if (!read_key(*data_rec, needs_encrypt, &key)) return false;
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uint64_t nr_sec;
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if (!get_number_of_sectors(data_rec->blk_device, &nr_sec)) return false;
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std::string crypto_blkdev;
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if (!create_crypto_blk_dev(kDmNameUserdata, nr_sec, DEFAULT_KEY_TARGET_TYPE,
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default_key_params(data_rec->blk_device, key), &crypto_blkdev))
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return false;
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// FIXME handle the corrupt case
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if (needs_encrypt) {
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LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
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off64_t size_already_done = 0;
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auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), data_rec->blk_device.data(), nr_sec,
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&size_already_done, nr_sec, 0, false);
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if (rc != 0) {
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LOG(ERROR) << "Inplace crypto failed with code: " << rc;
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return false;
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}
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if (static_cast<uint64_t>(size_already_done) != nr_sec) {
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LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done;
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return false;
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}
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LOG(INFO) << "Inplace encryption complete";
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}
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LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;
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mount_via_fs_mgr(data_rec->mount_point.c_str(), crypto_blkdev.c_str());
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return true;
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}
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