2 * Copyright (C) 2016 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include "MetadataCrypt.h"
18 #include "KeyBuffer.h"
23 #include <sys/param.h>
25 #include <sys/types.h>
27 #include <android-base/logging.h>
28 #include <android-base/properties.h>
29 #include <android-base/strings.h>
30 #include <android-base/unique_fd.h>
31 #include <cutils/fs.h>
34 #include <libgsi/libgsi.h>
36 #include "Checkpoint.h"
37 #include "CryptoType.h"
38 #include "EncryptInplace.h"
39 #include "KeyStorage.h"
41 #include "Keymaster.h"
50 using android::fs_mgr::FstabEntry;
51 using android::fs_mgr::GetEntryForMountPoint;
52 using android::vold::KeyBuffer;
53 using namespace android::dm;
55 // Parsed from metadata options
56 struct CryptoOptions {
57 struct CryptoType cipher = invalid_crypto_type;
58 bool use_legacy_options_format = false;
59 bool set_dun = true; // Non-legacy driver always sets DUN
60 bool use_hw_wrapped_key = false;
63 static const std::string kDmNameUserdata = "userdata";
65 // The first entry in this table is the default crypto type.
66 constexpr CryptoType supported_crypto_types[] = {aes_256_xts, adiantum};
68 static_assert(validateSupportedCryptoTypes(64, supported_crypto_types,
69 array_length(supported_crypto_types)),
70 "We have a CryptoType which was incompletely constructed.");
72 constexpr CryptoType legacy_aes_256_xts =
73 CryptoType().set_config_name("aes-256-xts").set_kernel_name("AES-256-XTS").set_keysize(64);
75 static_assert(isValidCryptoType(64, legacy_aes_256_xts),
76 "We have a CryptoType which was incompletely constructed.");
78 // Returns KeyGeneration suitable for key as described in CryptoOptions
79 const KeyGeneration makeGen(const CryptoOptions& options) {
80 return KeyGeneration{options.cipher.get_keysize(), true, options.use_hw_wrapped_key};
83 static bool mount_via_fs_mgr(const char* mount_point, const char* blk_device) {
84 // fs_mgr_do_mount runs fsck. Use setexeccon to run trusted
85 // partitions in the fsck domain.
86 if (setexeccon(android::vold::sFsckContext)) {
87 PLOG(ERROR) << "Failed to setexeccon";
90 auto mount_rc = fs_mgr_do_mount(&fstab_default, const_cast<char*>(mount_point),
91 const_cast<char*>(blk_device), nullptr,
92 android::vold::cp_needsCheckpoint(), true);
93 if (setexeccon(nullptr)) {
94 PLOG(ERROR) << "Failed to clear setexeccon";
98 LOG(ERROR) << "fs_mgr_do_mount failed with rc " << mount_rc;
101 LOG(DEBUG) << "Mounted " << mount_point;
105 static bool read_key(const std::string& metadata_key_dir, const KeyGeneration& gen,
107 if (metadata_key_dir.empty()) {
108 LOG(ERROR) << "Failed to get metadata_key_dir";
112 auto dir = metadata_key_dir + "/key";
113 LOG(DEBUG) << "metadata_key_dir/key: " << dir;
114 if (!MkdirsSync(dir, 0700)) return false;
115 auto temp = metadata_key_dir + "/tmp";
116 return retrieveOrGenerateKey(dir, temp, kEmptyAuthentication, gen, key);
119 static bool get_number_of_sectors(const std::string& real_blkdev, uint64_t* nr_sec) {
120 if (android::vold::GetBlockDev512Sectors(real_blkdev, nr_sec) != android::OK) {
121 PLOG(ERROR) << "Unable to measure size of " << real_blkdev;
127 static bool create_crypto_blk_dev(const std::string& dm_name, const std::string& blk_device,
128 const KeyBuffer& key, const CryptoOptions& options,
129 std::string* crypto_blkdev, uint64_t* nr_sec) {
130 if (!get_number_of_sectors(blk_device, nr_sec)) return false;
131 // TODO(paulcrowley): don't hardcode that DmTargetDefaultKey uses 4096-byte
135 KeyBuffer module_key;
136 if (options.use_hw_wrapped_key) {
137 if (!exportWrappedStorageKey(key, &module_key)) {
138 LOG(ERROR) << "Failed to get ephemeral wrapped key";
145 KeyBuffer hex_key_buffer;
146 if (android::vold::StrToHex(module_key, hex_key_buffer) != android::OK) {
147 LOG(ERROR) << "Failed to turn key to hex";
150 std::string hex_key(hex_key_buffer.data(), hex_key_buffer.size());
152 auto target = std::make_unique<DmTargetDefaultKey>(0, *nr_sec, options.cipher.get_kernel_name(),
153 hex_key, blk_device, 0);
154 if (options.use_legacy_options_format) target->SetUseLegacyOptionsFormat();
155 if (options.set_dun) target->SetSetDun();
156 if (options.use_hw_wrapped_key) target->SetWrappedKeyV0();
159 table.AddTarget(std::move(target));
161 auto& dm = DeviceMapper::Instance();
162 if (!dm.CreateDevice(dm_name, table, crypto_blkdev, std::chrono::seconds(5))) {
163 PLOG(ERROR) << "Could not create default-key device " << dm_name;
169 static const CryptoType& lookup_cipher(const std::string& cipher_name) {
170 if (cipher_name.empty()) return supported_crypto_types[0];
171 for (size_t i = 0; i < array_length(supported_crypto_types); i++) {
172 if (cipher_name == supported_crypto_types[i].get_config_name()) {
173 return supported_crypto_types[i];
176 return invalid_crypto_type;
179 static bool parse_options(const std::string& options_string, CryptoOptions* options) {
180 auto parts = android::base::Split(options_string, ":");
181 if (parts.size() < 1 || parts.size() > 2) {
182 LOG(ERROR) << "Invalid metadata encryption option: " << options_string;
185 std::string cipher_name = parts[0];
186 options->cipher = lookup_cipher(cipher_name);
187 if (options->cipher.get_kernel_name() == nullptr) {
188 LOG(ERROR) << "No metadata cipher named " << cipher_name << " found";
192 if (parts.size() == 2) {
193 if (parts[1] == "wrappedkey_v0") {
194 options->use_hw_wrapped_key = true;
196 LOG(ERROR) << "Invalid metadata encryption flag: " << parts[1];
203 bool fscrypt_mount_metadata_encrypted(const std::string& blk_device, const std::string& mount_point,
204 bool needs_encrypt, bool should_format,
205 const std::string& fs_type) {
206 LOG(DEBUG) << "fscrypt_mount_metadata_encrypted: " << mount_point
207 << " encrypt: " << needs_encrypt << " format: " << should_format << " with "
209 auto encrypted_state = android::base::GetProperty("ro.crypto.state", "");
210 if (encrypted_state != "" && encrypted_state != "encrypted") {
211 LOG(DEBUG) << "fscrypt_enable_crypto got unexpected starting state: " << encrypted_state;
215 auto data_rec = GetEntryForMountPoint(&fstab_default, mount_point);
217 LOG(ERROR) << "Failed to get data_rec for " << mount_point;
221 unsigned int options_format_version = android::base::GetUintProperty<unsigned int>(
222 "ro.crypto.dm_default_key.options_format.version",
223 (GetFirstApiLevel() <= __ANDROID_API_Q__ ? 1 : 2));
225 CryptoOptions options;
226 if (options_format_version == 1) {
227 if (!data_rec->metadata_encryption.empty()) {
228 LOG(ERROR) << "metadata_encryption options cannot be set in legacy mode";
231 options.cipher = legacy_aes_256_xts;
232 options.use_legacy_options_format = true;
233 options.set_dun = android::base::GetBoolProperty("ro.crypto.set_dun", false);
234 if (!options.set_dun && data_rec->fs_mgr_flags.checkpoint_blk) {
236 << "Block checkpoints and metadata encryption require ro.crypto.set_dun option";
239 } else if (options_format_version == 2) {
240 if (!parse_options(data_rec->metadata_encryption, &options)) return false;
242 LOG(ERROR) << "Unknown options_format_version: " << options_format_version;
246 auto gen = needs_encrypt ? makeGen(options) : neverGen();
248 if (!read_key(data_rec->metadata_key_dir, gen, &key)) return false;
250 std::string crypto_blkdev;
252 if (!create_crypto_blk_dev(kDmNameUserdata, blk_device, key, options, &crypto_blkdev, &nr_sec))
259 if (fs_type == "ext4") {
260 error = ext4::Format(crypto_blkdev, 0, mount_point);
261 } else if (fs_type == "f2fs") {
262 error = f2fs::Format(crypto_blkdev);
264 LOG(ERROR) << "Unknown filesystem type: " << fs_type;
267 LOG(DEBUG) << "Format (err=" << error << ") " << crypto_blkdev << " on " << mount_point;
268 if (error != 0) return false;
270 if (!encrypt_inplace(crypto_blkdev, blk_device, nr_sec, false)) return false;
274 LOG(DEBUG) << "Mounting metadata-encrypted filesystem:" << mount_point;
275 mount_via_fs_mgr(mount_point.c_str(), crypto_blkdev.c_str());
277 // Record that there's at least one fstab entry with metadata encryption
278 if (!android::base::SetProperty("ro.crypto.metadata.enabled", "true")) {
279 LOG(WARNING) << "failed to set ro.crypto.metadata.enabled"; // This isn't fatal
284 static bool get_volume_options(CryptoOptions* options) {
285 return parse_options(android::base::GetProperty("ro.crypto.volume.metadata.encryption", ""),
289 bool defaultkey_volume_keygen(KeyGeneration* gen) {
290 CryptoOptions options;
291 if (!get_volume_options(&options)) return false;
292 *gen = makeGen(options);
296 bool defaultkey_setup_ext_volume(const std::string& label, const std::string& blk_device,
297 const KeyBuffer& key, std::string* out_crypto_blkdev) {
298 LOG(DEBUG) << "defaultkey_setup_ext_volume: " << label << " " << blk_device;
300 CryptoOptions options;
301 if (!get_volume_options(&options)) return false;
303 return create_crypto_blk_dev(label, blk_device, key, options, out_crypto_blkdev, &nr_sec);
306 bool destroy_dsu_metadata_key(const std::string& dsu_slot) {
307 LOG(DEBUG) << "destroy_dsu_metadata_key: " << dsu_slot;
309 const auto dsu_metadata_key_dir = android::gsi::GetDsuMetadataKeyDir(dsu_slot);
310 if (!pathExists(dsu_metadata_key_dir)) {
311 LOG(DEBUG) << "DSU metadata_key_dir doesn't exist, nothing to remove: "
312 << dsu_metadata_key_dir;
316 // Ensure that the DSU key directory is different from the host OS'.
317 // Under normal circumstances, this should never happen, but handle it just in case.
318 if (auto data_rec = GetEntryForMountPoint(&fstab_default, "/data")) {
319 if (dsu_metadata_key_dir == data_rec->metadata_key_dir) {
320 LOG(ERROR) << "DSU metadata_key_dir is same as host OS: " << dsu_metadata_key_dir;
326 for (auto suffix : {"/key", "/tmp"}) {
327 const auto key_path = dsu_metadata_key_dir + suffix;
328 if (pathExists(key_path)) {
329 LOG(DEBUG) << "Destroy key: " << key_path;
330 if (!android::vold::destroyKey(key_path)) {
331 LOG(ERROR) << "Failed to destroyKey(): " << key_path;
340 LOG(DEBUG) << "Remove DSU metadata_key_dir: " << dsu_metadata_key_dir;
341 // DeleteDirContentsAndDir() already logged any error, so don't log repeatedly.
342 return android::vold::DeleteDirContentsAndDir(dsu_metadata_key_dir) == android::OK;
346 } // namespace android