MetadataCrypt.cpp - platform/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 "KeyBuffer.h"

 #include <algorithm>
 #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/file.h>
 #include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <android-base/unique_fd.h>
 #include <cutils/fs.h>
 #include <fs_mgr.h>

 #include "Checkpoint.h"
 #include "EncryptInplace.h"
 #include "KeyStorage.h"
 #include "KeyUtil.h"
 #include "Keymaster.h"
 #include "Utils.h"
 #include "VoldUtil.h"

 #define DM_CRYPT_BUF_SIZE 4096
 #define TABLE_LOAD_RETRIES 10
 #define DEFAULT_KEY_TARGET_TYPE "default-key"

 using android::fs_mgr::FstabEntry;
 using android::fs_mgr::GetEntryForMountPoint;
 using android::vold::KeyBuffer;

 static const std::string kDmNameUserdata = "userdata";

 static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
 static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";

 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(android::vold::sFsckContext)) {
         PLOG(ERROR) << "Failed to setexeccon";
         return false;
     }
     auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
                                     const_cast<char*>(blk_device), nullptr,
                                     android::vold::cp_needsCheckpoint());
     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;
 }

 namespace android {
 namespace vold {

 // Note: It is possible to orphan a key if it is removed before deleting
 // Update this once keymaster APIs change, and we have a proper commit.
 static void commit_key(const std::string& dir) {
     while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
         LOG(ERROR) << "Wait for boot timed out";
     }
     Keymaster keymaster;
     auto keyPath = dir + "/" + kFn_keymaster_key_blob;
     auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
     std::string key;

     if (!android::base::ReadFileToString(keyPath, &key)) {
         LOG(ERROR) << "Failed to read old key: " << dir;
         return;
     }
     if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
         PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
         return;
     }
     if (!keymaster.deleteKey(key)) {
         LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
     }
     LOG(INFO) << "Old Key deleted: " << dir;
 }

 static bool read_key(const FstabEntry& data_rec, bool create_if_absent, KeyBuffer* key) {
     if (data_rec.key_dir.empty()) {
         LOG(ERROR) << "Failed to get key_dir";
         return false;
     }
     std::string key_dir = data_rec.key_dir;
     std::string sKey;
     auto dir = key_dir + "/key";
     LOG(DEBUG) << "key_dir/key: " << dir;
     if (fs_mkdirs(dir.c_str(), 0700)) {
         PLOG(ERROR) << "Creating directories: " << dir;
         return false;
     }
     auto temp = key_dir + "/tmp";
     auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
     /* If we have a leftover upgraded key, delete it.
      * We either failed an update and must return to the old key,
      * or we rebooted before commiting the keys in a freak accident.
      * Either way, we can re-upgrade the key if we need to.
      */
     Keymaster keymaster;
     if (pathExists(newKeyPath)) {
         if (!android::base::ReadFileToString(newKeyPath, &sKey))
             LOG(ERROR) << "Failed to read old key: " << dir;
         else if (!keymaster.deleteKey(sKey))
             LOG(ERROR) << "Old key deletion failed, continuing anyway: " << dir;
         else
             unlink(newKeyPath.c_str());
     }
     bool needs_cp = cp_needsCheckpoint();
     if (!android::vold::retrieveKey(create_if_absent, dir, temp, key, needs_cp)) return false;
     if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
     return true;
 }

 }  // namespace vold
 }  // namespace android

 static KeyBuffer default_key_params(const std::string& real_blkdev, const KeyBuffer& key) {
     KeyBuffer hex_key;
     if (android::vold::StrToHex(key, hex_key) != android::OK) {
         LOG(ERROR) << "Failed to turn key to hex";
         return KeyBuffer();
     }
     auto res = KeyBuffer() + "AES-256-XTS " + hex_key + " " + real_blkdev.c_str() + " 0";
     return res;
 }

 static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
     if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {
         PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
         return false;
     }
     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 KeyBuffer& crypt_params,
                                   std::string* crypto_blkdev) {
     android::base::unique_fd dm_fd(
         TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR | O_CLOEXEC, 0)));
     if (dm_fd == -1) {
         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);
     size_t paramix = io->data_start + sizeof(struct dm_target_spec);
     size_t nullix = paramix + crypt_params.size();
     size_t 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));
     memcpy(buffer + paramix, crypt_params.data(),
            std::min(crypt_params.size(), 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;
 }

 bool fscrypt_mount_metadata_encrypted(const std::string& mount_point, bool needs_encrypt) {
     LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
     auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
     if (encrypted_state != "") {
         LOG(DEBUG) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
         return false;
     }

     auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
     if (!data_rec) {
         LOG(ERROR) << "Failed to get data_rec";
         return false;
     }
     KeyBuffer key;
     if (!read_key(*data_rec, needs_encrypt, &key)) 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
     if (needs_encrypt) {
         LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
         off64_t size_already_done = 0;
         auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), data_rec->blk_device.data(), nr_sec,
                                          &size_already_done, nr_sec, 0, false);
         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";
     }

     LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;
     mount_via_fs_mgr(data_rec->mount_point.c_str(), crypto_blkdev.c_str());
     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 "KeyBuffer.h"

	#include <algorithm>
	#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/file.h>
	#include <android-base/logging.h>
	#include <android-base/properties.h>
	#include <android-base/unique_fd.h>
	#include <cutils/fs.h>
	#include <fs_mgr.h>

	#include "Checkpoint.h"
	#include "EncryptInplace.h"
	#include "KeyStorage.h"
	#include "KeyUtil.h"
	#include "Keymaster.h"
	#include "Utils.h"
	#include "VoldUtil.h"

	#define DM_CRYPT_BUF_SIZE 4096
	#define TABLE_LOAD_RETRIES 10
	#define DEFAULT_KEY_TARGET_TYPE "default-key"

	using android::fs_mgr::FstabEntry;
	using android::fs_mgr::GetEntryForMountPoint;
	using android::vold::KeyBuffer;

	static const std::string kDmNameUserdata = "userdata";

	static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
	static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";

	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(android::vold::sFsckContext)) {
	PLOG(ERROR) << "Failed to setexeccon";
	return false;
	}
	auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
	const_cast<char*>(blk_device), nullptr,
	android::vold::cp_needsCheckpoint());
	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;
	}

	namespace android {
	namespace vold {

	// Note: It is possible to orphan a key if it is removed before deleting
	// Update this once keymaster APIs change, and we have a proper commit.
	static void commit_key(const std::string& dir) {
	while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
	LOG(ERROR) << "Wait for boot timed out";
	}
	Keymaster keymaster;
	auto keyPath = dir + "/" + kFn_keymaster_key_blob;
	auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
	std::string key;

	if (!android::base::ReadFileToString(keyPath, &key)) {
	LOG(ERROR) << "Failed to read old key: " << dir;
	return;
	}
	if (rename(newKeyPath.c_str(), keyPath.c_str()) != 0) {
	PLOG(ERROR) << "Unable to move upgraded key to location: " << keyPath;
	return;
	}
	if (!keymaster.deleteKey(key)) {
	LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
	}
	LOG(INFO) << "Old Key deleted: " << dir;
	}

	static bool read_key(const FstabEntry& data_rec, bool create_if_absent, KeyBuffer* key) {
	if (data_rec.key_dir.empty()) {
	LOG(ERROR) << "Failed to get key_dir";
	return false;
	}
	std::string key_dir = data_rec.key_dir;
	std::string sKey;
	auto dir = key_dir + "/key";
	LOG(DEBUG) << "key_dir/key: " << dir;
	if (fs_mkdirs(dir.c_str(), 0700)) {
	PLOG(ERROR) << "Creating directories: " << dir;
	return false;
	}
	auto temp = key_dir + "/tmp";
	auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
	/* If we have a leftover upgraded key, delete it.
	* We either failed an update and must return to the old key,
	* or we rebooted before commiting the keys in a freak accident.
	* Either way, we can re-upgrade the key if we need to.
	*/
	Keymaster keymaster;
	if (pathExists(newKeyPath)) {
	if (!android::base::ReadFileToString(newKeyPath, &sKey))
	LOG(ERROR) << "Failed to read old key: " << dir;
	else if (!keymaster.deleteKey(sKey))
	LOG(ERROR) << "Old key deletion failed, continuing anyway: " << dir;
	else
	unlink(newKeyPath.c_str());
	}
	bool needs_cp = cp_needsCheckpoint();
	if (!android::vold::retrieveKey(create_if_absent, dir, temp, key, needs_cp)) return false;
	if (needs_cp && pathExists(newKeyPath)) std::thread(commit_key, dir).detach();
	return true;
	}

	} // namespace vold
	} // namespace android

	static KeyBuffer default_key_params(const std::string& real_blkdev, const KeyBuffer& key) {
	KeyBuffer hex_key;
	if (android::vold::StrToHex(key, hex_key) != android::OK) {
	LOG(ERROR) << "Failed to turn key to hex";
	return KeyBuffer();
	}
	auto res = KeyBuffer() + "AES-256-XTS " + hex_key + " " + real_blkdev.c_str() + " 0";
	return res;
	}

	static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
	if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {
	PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
	return false;
	}
	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 KeyBuffer& crypt_params,
	std::string* crypto_blkdev) {
	android::base::unique_fd dm_fd(
	TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR \| O_CLOEXEC, 0)));
	if (dm_fd == -1) {
	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);
	size_t paramix = io->data_start + sizeof(struct dm_target_spec);
	size_t nullix = paramix + crypt_params.size();
	size_t 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));
	memcpy(buffer + paramix, crypt_params.data(),
	std::min(crypt_params.size(), 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;
	}

	bool fscrypt_mount_metadata_encrypted(const std::string& mount_point, bool needs_encrypt) {
	LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point << " " << needs_encrypt;
	auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
	if (encrypted_state != "") {
	LOG(DEBUG) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
	return false;
	}

	auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
	if (!data_rec) {
	LOG(ERROR) << "Failed to get data_rec";
	return false;
	}
	KeyBuffer key;
	if (!read_key(*data_rec, needs_encrypt, &key)) 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
	if (needs_encrypt) {
	LOG(INFO) << "Beginning inplace encryption, nr_sec: " << nr_sec;
	off64_t size_already_done = 0;
	auto rc = cryptfs_enable_inplace(crypto_blkdev.data(), data_rec->blk_device.data(), nr_sec,
	&size_already_done, nr_sec, 0, false);
	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";
	}

	LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;
	mount_via_fs_mgr(data_rec->mount_point.c_str(), crypto_blkdev.c_str());
	return true;
	}