Add support for metadata encryption
Support encrypting metadata in /userdata using the dm-default-key
driver with a key in the /metadata partition.
Bug: 29189559
Test: Angler & Marlin build and boot
Change-Id: I716b117508d4bb4f6a4039293acb848cbc60f67b
diff --git a/MetadataCrypt.cpp b/MetadataCrypt.cpp
new file mode 100644
index 0000000..b707549
--- /dev/null
+++ b/MetadataCrypt.cpp
@@ -0,0 +1,312 @@
+/*
+ * Copyright (C) 2016 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 "MetadataCrypt.h"
+
+#include <string>
+#include <thread>
+#include <vector>
+
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <linux/dm-ioctl.h>
+
+#include <android-base/logging.h>
+#include <cutils/properties.h>
+#include <fs_mgr.h>
+
+#include "AutoCloseFD.h"
+#include "EncryptInplace.h"
+#include "KeyStorage.h"
+#include "KeyUtil.h"
+#include "secontext.h"
+#include "Utils.h"
+#include "VoldUtil.h"
+
+extern struct fstab *fstab;
+#define DM_CRYPT_BUF_SIZE 4096
+#define TABLE_LOAD_RETRIES 10
+#define DEFAULT_KEY_TARGET_TYPE "default-key"
+
+static const std::string kDmNameUserdata = "userdata";
+
+static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
+ // fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
+ // partitions in the fsck domain.
+ if (setexeccon(secontextFsck())) {
+ PLOG(ERROR) << "Failed to setexeccon";
+ return false;
+ }
+ auto mount_rc = fs_mgr_do_mount(fstab, const_cast<char*>(mount_point),
+ const_cast<char*>(blk_device), nullptr);
+ if (setexeccon(nullptr)) {
+ PLOG(ERROR) << "Failed to clear setexeccon";
+ return false;
+ }
+ if (mount_rc != 0) {
+ LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc;
+ return false;
+ }
+ LOG(DEBUG) << "Mounted " << mount_point;
+ return true;
+}
+
+static bool read_key(bool create_if_absent, std::string* key) {
+ auto data_rec = fs_mgr_get_crypt_entry(fstab);
+ if (!data_rec) {
+ LOG(ERROR) << "Failed to get data_rec";
+ return false;
+ }
+ if (!data_rec->key_dir) {
+ LOG(ERROR) << "Failed to get key_dir";
+ return false;
+ }
+ LOG(DEBUG) << "key_dir: " << data_rec->key_dir;
+ if (!android::vold::pathExists(data_rec->key_dir)) {
+ if (mkdir(data_rec->key_dir, 0777) != 0) {
+ PLOG(ERROR) << "Unable to create: " << data_rec->key_dir;
+ return false;
+ }
+ LOG(DEBUG) << "Created: " << data_rec->key_dir;
+ }
+ std::string key_dir = data_rec->key_dir;
+ auto dir = key_dir + "/key";
+ auto temp = key_dir + "/tmp";
+ if (!android::vold::retrieveKey(create_if_absent, dir, temp, key)) return false;
+ return true;
+}
+
+static std::string default_key_params(const std::string& real_blkdev, const std::string& key) {
+ std::string hex_key;
+ if (android::vold::StrToHex(key, hex_key) != android::OK) {
+ LOG(ERROR) << "Failed to turn key to hex";
+ return "";
+ }
+ auto res = std::string() + "AES-256-XTS " + hex_key + " " + real_blkdev + " 0";
+ LOG(DEBUG) << "crypt_params: " << res;
+ return res;
+}
+
+static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t *nr_sec) {
+ AutoCloseFD dev_fd(real_blkdev, O_RDONLY);
+ if (!dev_fd) {
+ PLOG(ERROR) << "Unable to open " << real_blkdev << " to measure size";
+ return false;
+ }
+ unsigned long res;
+ // TODO: should use BLKGETSIZE64
+ get_blkdev_size(dev_fd.get(), &res);
+ if (res == 0) {
+ PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
+ return false;
+ }
+ *nr_sec = res;
+ return true;
+}
+
+static struct dm_ioctl* dm_ioctl_init(char *buffer, size_t buffer_size,
+ const std::string& dm_name) {
+ if (buffer_size < sizeof(dm_ioctl)) {
+ LOG(ERROR) << "dm_ioctl buffer too small";
+ return nullptr;
+ }
+
+ memset(buffer, 0, buffer_size);
+ struct dm_ioctl* io = (struct dm_ioctl*) buffer;
+ io->data_size = buffer_size;
+ io->data_start = sizeof(struct dm_ioctl);
+ io->version[0] = 4;
+ io->version[1] = 0;
+ io->version[2] = 0;
+ io->flags = 0;
+ dm_name.copy(io->name, sizeof(io->name));
+ return io;
+}
+
+static bool create_crypto_blk_dev(const std::string& dm_name, uint64_t nr_sec,
+ const std::string& target_type, const std::string& crypt_params,
+ std::string* crypto_blkdev) {
+ AutoCloseFD dm_fd("/dev/device-mapper", O_RDWR);
+ if (!dm_fd) {
+ PLOG(ERROR) << "Cannot open device-mapper";
+ return false;
+ }
+ alignas(struct dm_ioctl) char buffer[DM_CRYPT_BUF_SIZE];
+ auto io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
+ if (!io || ioctl(dm_fd.get(), DM_DEV_CREATE, io) != 0) {
+ PLOG(ERROR) << "Cannot create dm-crypt device " << dm_name;
+ return false;
+ }
+
+ // Get the device status, in particular, the name of its device file
+ io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
+ if (ioctl(dm_fd.get(), DM_DEV_STATUS, io) != 0) {
+ PLOG(ERROR) << "Cannot retrieve dm-crypt device status " << dm_name;
+ return false;
+ }
+ *crypto_blkdev = std::string() + "/dev/block/dm-" + std::to_string(
+ (io->dev & 0xff) | ((io->dev >> 12) & 0xfff00));
+
+ io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
+ unsigned long paramix = io->data_start + sizeof(struct dm_target_spec);
+ unsigned long nullix = paramix + crypt_params.size();
+ unsigned long endix = (nullix + 1 + 7) & 8; // Add room for \0 and align to 8 byte boundary
+
+ if (endix > sizeof(buffer)) {
+ LOG(ERROR) << "crypt_params too big for DM_CRYPT_BUF_SIZE";
+ return false;
+ }
+
+ io->target_count = 1;
+ auto tgt = (struct dm_target_spec *) (buffer + io->data_start);
+ tgt->status = 0;
+ tgt->sector_start = 0;
+ tgt->length = nr_sec;
+ target_type.copy(tgt->target_type, sizeof(tgt->target_type));
+ crypt_params.copy(buffer + paramix, sizeof(buffer) - paramix);
+ buffer[nullix] = '\0';
+ tgt->next = endix;
+
+ for (int i = 0; ; i++) {
+ if (ioctl(dm_fd.get(), DM_TABLE_LOAD, io) == 0) {
+ break;
+ }
+ if (i+1 >= TABLE_LOAD_RETRIES) {
+ PLOG(ERROR) << "DM_TABLE_LOAD ioctl failed";
+ return false;
+ }
+ PLOG(INFO) << "DM_TABLE_LOAD ioctl failed, retrying";
+ usleep(500000);
+ }
+
+ // Resume this device to activate it
+ io = dm_ioctl_init(buffer, sizeof(buffer), dm_name);
+ if (ioctl(dm_fd.get(), DM_DEV_SUSPEND, io)) {
+ PLOG(ERROR) << "Cannot resume dm-crypt device " << dm_name;
+ return false;
+ }
+ return true;
+}
+
+#define DATA_PREP_TIMEOUT 1000
+static bool prep_data_fs(void)
+{
+ // NOTE: post_fs_data results in init calling back around to vold, so all
+ // callers to this method must be async
+
+ /* Do the prep of the /data filesystem */
+ property_set("vold.post_fs_data_done", "0");
+ property_set("vold.decrypt", "trigger_post_fs_data");
+ LOG(DEBUG) << "Waiting for post_fs_data_done";
+
+ /* Wait a max of 50 seconds, hopefully it takes much less */
+ for (int i = 0; ; i++) {
+ char p[PROPERTY_VALUE_MAX];
+
+ property_get("vold.post_fs_data_done", p, "0");
+ if (*p == '1') {
+ LOG(INFO) << "Successful data prep";
+ return true;
+ }
+ if (i + 1 == DATA_PREP_TIMEOUT) {
+ LOG(ERROR) << "post_fs_data timed out";
+ return false;
+ }
+ usleep(50000);
+ }
+}
+
+static void async_kick_off() {
+ LOG(DEBUG) << "Asynchronously restarting framework";
+ sleep(2); // TODO: this mirrors cryptfs, but can it be made shorter?
+ property_set("vold.decrypt", "trigger_load_persist_props");
+ if (!prep_data_fs()) return;
+ /* startup service classes main and late_start */
+ property_set("vold.decrypt", "trigger_restart_framework");
+}
+
+bool e4crypt_mount_metadata_encrypted() {
+ LOG(DEBUG) << "e4crypt_mount_default_encrypted";
+ std::string key;
+ if (!read_key(false, &key)) return false;
+ auto data_rec = fs_mgr_get_crypt_entry(fstab);
+ if (!data_rec) {
+ LOG(ERROR) << "Failed to get data_rec";
+ return false;
+ }
+ uint64_t nr_sec;
+ if (!get_number_of_sectors(data_rec->blk_device, &nr_sec)) return false;
+ std::string crypto_blkdev;
+ if (!create_crypto_blk_dev(kDmNameUserdata, nr_sec, DEFAULT_KEY_TARGET_TYPE,
+ default_key_params(data_rec->blk_device, key), &crypto_blkdev)) return false;
+ // FIXME handle the corrupt case
+
+ LOG(DEBUG) << "Restarting filesystem for metadata encryption";
+ mount_via_fs_mgr(data_rec->mount_point, crypto_blkdev.c_str());
+ std::thread(&async_kick_off).detach();
+ return true;
+}
+
+bool e4crypt_enable_crypto() {
+ LOG(DEBUG) << "e4crypt_enable_crypto";
+ char encrypted_state[PROPERTY_VALUE_MAX];
+ property_get("ro.crypto.state", encrypted_state, "");
+ if (strcmp(encrypted_state, "")) {
+ LOG(DEBUG) << "e4crypt_enable_crypto got unexpected starting state: " << encrypted_state;
+ return false;
+ }
+
+ std::string key_ref;
+ if (!read_key(true, &key_ref)) return false;
+
+ auto data_rec = fs_mgr_get_crypt_entry(fstab);
+ if (!data_rec) {
+ LOG(ERROR) << "Failed to get data_rec";
+ return false;
+ }
+ uint64_t nr_sec;
+ if (!get_number_of_sectors(data_rec->blk_device, &nr_sec)) return false;
+
+ std::string crypto_blkdev;
+ if (!create_crypto_blk_dev(kDmNameUserdata, nr_sec, DEFAULT_KEY_TARGET_TYPE,
+ default_key_params(data_rec->blk_device, key_ref), &crypto_blkdev)) return false;
+
+ LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
+ off64_t size_already_done = 0;
+ auto rc = cryptfs_enable_inplace(const_cast<char *>(crypto_blkdev.c_str()),
+ data_rec->blk_device, nr_sec, &size_already_done, nr_sec, 0);
+ if (rc != 0) {
+ LOG(ERROR) << "Inplace crypto failed with code: " << rc;
+ return false;
+ }
+ if (static_cast<uint64_t>(size_already_done) != nr_sec) {
+ LOG(ERROR) << "Inplace crypto only got up to sector: " << size_already_done;
+ return false;
+ }
+ LOG(INFO) << "Inplace encryption complete";
+
+ property_set("ro.crypto.state", "encrypted");
+ property_set("ro.crypto.type", "file");
+
+ mount_via_fs_mgr(data_rec->mount_point, crypto_blkdev.c_str());
+ property_set("vold.decrypt", "trigger_reset_main");
+ std::thread(&async_kick_off).detach();
+ return true;
+}