MetadataCrypt.cpp - SHIFTPHONES/android_system_vold - Gitiles

 /*
  * 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;
 }
	/*
	* 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;
	}