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Paul Crowley1ef25582016-01-21 20:26:12 +00001/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17#include "KeyStorage.h"
18
Daniel Rosenbergd2906b82019-06-07 14:18:14 -070019#include "Checkpoint.h"
Paul Crowley1ef25582016-01-21 20:26:12 +000020#include "Keymaster.h"
Paul Crowley63c18d32016-02-10 14:02:47 +000021#include "ScryptParameters.h"
Paul Crowley1ef25582016-01-21 20:26:12 +000022#include "Utils.h"
23
Daniel Rosenberga48730a2019-06-06 20:38:38 -070024#include <thread>
Paul Crowley1ef25582016-01-21 20:26:12 +000025#include <vector>
26
27#include <errno.h>
Paul Crowleydff8c722016-05-16 08:14:56 -070028#include <stdio.h>
Paul Crowley1ef25582016-01-21 20:26:12 +000029#include <sys/stat.h>
30#include <sys/types.h>
31#include <sys/wait.h>
32#include <unistd.h>
33
Paul Crowley6ab2cab2017-01-04 22:32:40 -080034#include <openssl/err.h>
35#include <openssl/evp.h>
Paul Crowley1ef25582016-01-21 20:26:12 +000036#include <openssl/sha.h>
37
38#include <android-base/file.h>
39#include <android-base/logging.h>
Daniel Rosenberga48730a2019-06-06 20:38:38 -070040#include <android-base/properties.h>
Daniel Rosenbergd2906b82019-06-07 14:18:14 -070041#include <android-base/unique_fd.h>
Paul Crowley1ef25582016-01-21 20:26:12 +000042
Paul Crowley63c18d32016-02-10 14:02:47 +000043#include <cutils/properties.h>
44
Paul Crowley320e5e12016-03-04 14:07:05 -080045#include <hardware/hw_auth_token.h>
Shawn Willden35f0f222020-01-16 13:21:42 -070046#include <keymasterV4_1/authorization_set.h>
47#include <keymasterV4_1/keymaster_utils.h>
Paul Crowley320e5e12016-03-04 14:07:05 -080048
Paul Crowley63c18d32016-02-10 14:02:47 +000049extern "C" {
50
51#include "crypto_scrypt.h"
Paul Crowley63c18d32016-02-10 14:02:47 +000052}
53
Paul Crowley1ef25582016-01-21 20:26:12 +000054namespace android {
55namespace vold {
56
Paul Crowleydf528a72016-03-09 09:31:37 -080057const KeyAuthentication kEmptyAuthentication{"", ""};
Paul Crowley05720802016-02-08 15:55:41 +000058
Paul Crowley1ef25582016-01-21 20:26:12 +000059static constexpr size_t AES_KEY_BYTES = 32;
60static constexpr size_t GCM_NONCE_BYTES = 12;
61static constexpr size_t GCM_MAC_BYTES = 16;
Paul Crowleydf528a72016-03-09 09:31:37 -080062static constexpr size_t SALT_BYTES = 1 << 4;
63static constexpr size_t SECDISCARDABLE_BYTES = 1 << 14;
64static constexpr size_t STRETCHED_BYTES = 1 << 6;
Paul Crowley1ef25582016-01-21 20:26:12 +000065
Shawn Willden785365b2018-01-20 09:37:36 -070066static constexpr uint32_t AUTH_TIMEOUT = 30; // Seconds
Paul Crowleyb3de3372016-04-27 12:58:41 -070067
Paul Crowley05720802016-02-08 15:55:41 +000068static const char* kCurrentVersion = "1";
Paul Crowley1ef25582016-01-21 20:26:12 +000069static const char* kRmPath = "/system/bin/rm";
70static const char* kSecdiscardPath = "/system/bin/secdiscard";
Paul Crowley63c18d32016-02-10 14:02:47 +000071static const char* kStretch_none = "none";
72static const char* kStretch_nopassword = "nopassword";
73static const std::string kStretchPrefix_scrypt = "scrypt ";
Paul Crowley6ab2cab2017-01-04 22:32:40 -080074static const char* kHashPrefix_secdiscardable = "Android secdiscardable SHA512";
75static const char* kHashPrefix_keygen = "Android key wrapping key generation SHA512";
Paul Crowley1ef25582016-01-21 20:26:12 +000076static const char* kFn_encrypted_key = "encrypted_key";
Paul Crowley05720802016-02-08 15:55:41 +000077static const char* kFn_keymaster_key_blob = "keymaster_key_blob";
Paul Crowleydff8c722016-05-16 08:14:56 -070078static const char* kFn_keymaster_key_blob_upgraded = "keymaster_key_blob_upgraded";
Paul Crowley63c18d32016-02-10 14:02:47 +000079static const char* kFn_salt = "salt";
Paul Crowley1ef25582016-01-21 20:26:12 +000080static const char* kFn_secdiscardable = "secdiscardable";
Paul Crowley05720802016-02-08 15:55:41 +000081static const char* kFn_stretching = "stretching";
82static const char* kFn_version = "version";
Paul Crowley1ef25582016-01-21 20:26:12 +000083
Paul Crowley13ffd8e2016-01-27 14:30:22 +000084static bool checkSize(const std::string& kind, size_t actual, size_t expected) {
Paul Crowley1ef25582016-01-21 20:26:12 +000085 if (actual != expected) {
Paul Crowleydf528a72016-03-09 09:31:37 -080086 LOG(ERROR) << "Wrong number of bytes in " << kind << ", expected " << expected << " got "
87 << actual;
Paul Crowley1ef25582016-01-21 20:26:12 +000088 return false;
89 }
90 return true;
91}
92
Paul Crowley26a53882017-10-26 11:16:39 -070093static void hashWithPrefix(char const* prefix, const std::string& tohash, std::string* res) {
Paul Crowley1ef25582016-01-21 20:26:12 +000094 SHA512_CTX c;
95
96 SHA512_Init(&c);
97 // Personalise the hashing by introducing a fixed prefix.
98 // Hashing applications should use personalization except when there is a
99 // specific reason not to; see section 4.11 of https://www.schneier.com/skein1.3.pdf
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800100 std::string hashingPrefix = prefix;
101 hashingPrefix.resize(SHA512_CBLOCK);
102 SHA512_Update(&c, hashingPrefix.data(), hashingPrefix.size());
103 SHA512_Update(&c, tohash.data(), tohash.size());
Paul Crowley26a53882017-10-26 11:16:39 -0700104 res->assign(SHA512_DIGEST_LENGTH, '\0');
105 SHA512_Final(reinterpret_cast<uint8_t*>(&(*res)[0]), &c);
Paul Crowley1ef25582016-01-21 20:26:12 +0000106}
107
Paul Crowleydf528a72016-03-09 09:31:37 -0800108static bool generateKeymasterKey(Keymaster& keymaster, const KeyAuthentication& auth,
109 const std::string& appId, std::string* key) {
Shawn Willden35351812018-01-22 09:08:32 -0700110 auto paramBuilder = km::AuthorizationSetBuilder()
Paul Crowleydf528a72016-03-09 09:31:37 -0800111 .AesEncryptionKey(AES_KEY_BYTES * 8)
Shawn Willden35351812018-01-22 09:08:32 -0700112 .GcmModeMinMacLen(GCM_MAC_BYTES * 8)
113 .Authorization(km::TAG_APPLICATION_ID, km::support::blob2hidlVec(appId));
Paul Crowley320e5e12016-03-04 14:07:05 -0800114 if (auth.token.empty()) {
115 LOG(DEBUG) << "Creating key that doesn't need auth token";
Shawn Willden35351812018-01-22 09:08:32 -0700116 paramBuilder.Authorization(km::TAG_NO_AUTH_REQUIRED);
Paul Crowley320e5e12016-03-04 14:07:05 -0800117 } else {
118 LOG(DEBUG) << "Auth token required for key";
119 if (auth.token.size() != sizeof(hw_auth_token_t)) {
120 LOG(ERROR) << "Auth token should be " << sizeof(hw_auth_token_t) << " bytes, was "
Paul Crowleydf528a72016-03-09 09:31:37 -0800121 << auth.token.size() << " bytes";
Paul Crowley320e5e12016-03-04 14:07:05 -0800122 return false;
123 }
Paul Crowleydf528a72016-03-09 09:31:37 -0800124 const hw_auth_token_t* at = reinterpret_cast<const hw_auth_token_t*>(auth.token.data());
Paul Crowleyd281de72018-08-30 15:25:19 -0700125 auto user_id = at->user_id; // Make a copy because at->user_id is unaligned.
126 paramBuilder.Authorization(km::TAG_USER_SECURE_ID, user_id);
Shawn Willden35351812018-01-22 09:08:32 -0700127 paramBuilder.Authorization(km::TAG_USER_AUTH_TYPE, km::HardwareAuthenticatorType::PASSWORD);
128 paramBuilder.Authorization(km::TAG_AUTH_TIMEOUT, AUTH_TIMEOUT);
Paul Crowley320e5e12016-03-04 14:07:05 -0800129 }
Shawn Willden8431fe22018-12-06 07:45:02 -0700130
131 auto paramsWithRollback = paramBuilder;
132 paramsWithRollback.Authorization(km::TAG_ROLLBACK_RESISTANCE);
133
134 // Generate rollback-resistant key if possible.
135 return keymaster.generateKey(paramsWithRollback, key) ||
136 keymaster.generateKey(paramBuilder, key);
Paul Crowley320e5e12016-03-04 14:07:05 -0800137}
138
Barani Muthukumaran3dfb0942020-02-03 13:06:45 -0800139bool generateWrappedStorageKey(KeyBuffer* key) {
140 Keymaster keymaster;
141 if (!keymaster) return false;
142 std::string key_temp;
143 auto paramBuilder = km::AuthorizationSetBuilder().AesEncryptionKey(AES_KEY_BYTES * 8);
Barani Muthukumaran3dfb0942020-02-03 13:06:45 -0800144 paramBuilder.Authorization(km::TAG_STORAGE_KEY);
Gaurav Kashyap75736a82020-09-11 15:24:01 -0700145 auto paramsWithRollback = paramBuilder;
146 paramsWithRollback.Authorization(km::TAG_ROLLBACK_RESISTANCE);
147 if (!keymaster.generateKey(paramsWithRollback, &key_temp)) {
148 if (!keymaster.generateKey(paramBuilder, &key_temp)) return false;
149 }
Barani Muthukumaran3dfb0942020-02-03 13:06:45 -0800150 *key = KeyBuffer(key_temp.size());
151 memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
152 return true;
153}
154
155bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key) {
156 Keymaster keymaster;
157 if (!keymaster) return false;
158 std::string key_temp;
159
160 if (!keymaster.exportKey(kmKey, &key_temp)) return false;
161 *key = KeyBuffer(key_temp.size());
162 memcpy(reinterpret_cast<void*>(key->data()), key_temp.c_str(), key->size());
163 return true;
164}
165
Shawn Willden35351812018-01-22 09:08:32 -0700166static std::pair<km::AuthorizationSet, km::HardwareAuthToken> beginParams(
167 const KeyAuthentication& auth, const std::string& appId) {
168 auto paramBuilder = km::AuthorizationSetBuilder()
169 .GcmModeMacLen(GCM_MAC_BYTES * 8)
170 .Authorization(km::TAG_APPLICATION_ID, km::support::blob2hidlVec(appId));
171 km::HardwareAuthToken authToken;
Paul Crowley320e5e12016-03-04 14:07:05 -0800172 if (!auth.token.empty()) {
173 LOG(DEBUG) << "Supplying auth token to Keymaster";
Shawn Willden35351812018-01-22 09:08:32 -0700174 authToken = km::support::hidlVec2AuthToken(km::support::blob2hidlVec(auth.token));
Paul Crowley320e5e12016-03-04 14:07:05 -0800175 }
Shawn Willden35351812018-01-22 09:08:32 -0700176 return {paramBuilder, authToken};
Paul Crowley1ef25582016-01-21 20:26:12 +0000177}
178
Paul Crowleydf528a72016-03-09 09:31:37 -0800179static bool readFileToString(const std::string& filename, std::string* result) {
Paul Crowleya051eb72016-03-08 16:08:32 -0800180 if (!android::base::ReadFileToString(filename, result)) {
Paul Crowleydf528a72016-03-09 09:31:37 -0800181 PLOG(ERROR) << "Failed to read from " << filename;
182 return false;
Paul Crowley13ffd8e2016-01-27 14:30:22 +0000183 }
184 return true;
185}
186
Paul Crowley26a53882017-10-26 11:16:39 -0700187static bool readRandomBytesOrLog(size_t count, std::string* out) {
188 auto status = ReadRandomBytes(count, *out);
189 if (status != OK) {
190 LOG(ERROR) << "Random read failed with status: " << status;
191 return false;
192 }
193 return true;
194}
195
196bool createSecdiscardable(const std::string& filename, std::string* hash) {
197 std::string secdiscardable;
198 if (!readRandomBytesOrLog(SECDISCARDABLE_BYTES, &secdiscardable)) return false;
199 if (!writeStringToFile(secdiscardable, filename)) return false;
200 hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash);
201 return true;
202}
203
204bool readSecdiscardable(const std::string& filename, std::string* hash) {
205 std::string secdiscardable;
206 if (!readFileToString(filename, &secdiscardable)) return false;
207 hashWithPrefix(kHashPrefix_secdiscardable, secdiscardable, hash);
208 return true;
209}
210
Daniel Rosenberga48730a2019-06-06 20:38:38 -0700211static void deferedKmDeleteKey(const std::string& kmkey) {
212 while (!android::base::WaitForProperty("vold.checkpoint_committed", "1")) {
213 LOG(ERROR) << "Wait for boot timed out";
214 }
215 Keymaster keymaster;
216 if (!keymaster || !keymaster.deleteKey(kmkey)) {
217 LOG(ERROR) << "Defered Key deletion failed during upgrade";
218 }
219}
220
221bool kmDeleteKey(Keymaster& keymaster, const std::string& kmKey) {
222 bool needs_cp = cp_needsCheckpoint();
223
224 if (needs_cp) {
225 std::thread(deferedKmDeleteKey, kmKey).detach();
226 LOG(INFO) << "Deferring Key deletion during upgrade";
227 return true;
228 } else {
229 return keymaster.deleteKey(kmKey);
230 }
231}
232
Shawn Willden35351812018-01-22 09:08:32 -0700233static KeymasterOperation begin(Keymaster& keymaster, const std::string& dir,
234 km::KeyPurpose purpose, const km::AuthorizationSet& keyParams,
235 const km::AuthorizationSet& opParams,
236 const km::HardwareAuthToken& authToken,
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800237 km::AuthorizationSet* outParams, bool keepOld) {
Paul Crowleydff8c722016-05-16 08:14:56 -0700238 auto kmKeyPath = dir + "/" + kFn_keymaster_key_blob;
239 std::string kmKey;
240 if (!readFileToString(kmKeyPath, &kmKey)) return KeymasterOperation();
Shawn Willden35351812018-01-22 09:08:32 -0700241 km::AuthorizationSet inParams(keyParams);
Janis Danisevskis8e537b82016-10-26 14:27:10 +0100242 inParams.append(opParams.begin(), opParams.end());
Paul Crowleydff8c722016-05-16 08:14:56 -0700243 for (;;) {
Shawn Willden35351812018-01-22 09:08:32 -0700244 auto opHandle = keymaster.begin(purpose, kmKey, inParams, authToken, outParams);
Paul Crowleydff8c722016-05-16 08:14:56 -0700245 if (opHandle) {
246 return opHandle;
247 }
Shawn Willden35351812018-01-22 09:08:32 -0700248 if (opHandle.errorCode() != km::ErrorCode::KEY_REQUIRES_UPGRADE) return opHandle;
Paul Crowleydff8c722016-05-16 08:14:56 -0700249 LOG(DEBUG) << "Upgrading key: " << dir;
250 std::string newKey;
251 if (!keymaster.upgradeKey(kmKey, keyParams, &newKey)) return KeymasterOperation();
252 auto newKeyPath = dir + "/" + kFn_keymaster_key_blob_upgraded;
253 if (!writeStringToFile(newKey, newKeyPath)) return KeymasterOperation();
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800254 if (!keepOld) {
255 if (rename(newKeyPath.c_str(), kmKeyPath.c_str()) != 0) {
256 PLOG(ERROR) << "Unable to move upgraded key to location: " << kmKeyPath;
257 return KeymasterOperation();
258 }
Woody Lin37c82f52019-03-11 20:58:20 +0800259 if (!android::vold::FsyncDirectory(dir)) {
260 LOG(ERROR) << "Key dir sync failed: " << dir;
261 return KeymasterOperation();
262 }
Daniel Rosenberga48730a2019-06-06 20:38:38 -0700263 if (!kmDeleteKey(keymaster, kmKey)) {
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800264 LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
265 }
Paul Crowleydff8c722016-05-16 08:14:56 -0700266 }
267 kmKey = newKey;
268 LOG(INFO) << "Key upgraded: " << dir;
269 }
270}
271
272static bool encryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir,
Shawn Willden35351812018-01-22 09:08:32 -0700273 const km::AuthorizationSet& keyParams,
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800274 const km::HardwareAuthToken& authToken, const KeyBuffer& message,
275 std::string* ciphertext, bool keepOld) {
Shawn Willden35351812018-01-22 09:08:32 -0700276 km::AuthorizationSet opParams;
277 km::AuthorizationSet outParams;
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800278 auto opHandle = begin(keymaster, dir, km::KeyPurpose::ENCRYPT, keyParams, opParams, authToken,
279 &outParams, keepOld);
Paul Crowleydff8c722016-05-16 08:14:56 -0700280 if (!opHandle) return false;
Shawn Willden35351812018-01-22 09:08:32 -0700281 auto nonceBlob = outParams.GetTagValue(km::TAG_NONCE);
Janis Danisevskis8e537b82016-10-26 14:27:10 +0100282 if (!nonceBlob.isOk()) {
Paul Crowleydff8c722016-05-16 08:14:56 -0700283 LOG(ERROR) << "GCM encryption but no nonce generated";
284 return false;
285 }
286 // nonceBlob here is just a pointer into existing data, must not be freed
Shawn Willden785365b2018-01-20 09:37:36 -0700287 std::string nonce(reinterpret_cast<const char*>(&nonceBlob.value()[0]),
288 nonceBlob.value().size());
Paul Crowleydff8c722016-05-16 08:14:56 -0700289 if (!checkSize("nonce", nonce.size(), GCM_NONCE_BYTES)) return false;
290 std::string body;
291 if (!opHandle.updateCompletely(message, &body)) return false;
292
293 std::string mac;
294 if (!opHandle.finish(&mac)) return false;
295 if (!checkSize("mac", mac.size(), GCM_MAC_BYTES)) return false;
296 *ciphertext = nonce + body + mac;
297 return true;
298}
299
300static bool decryptWithKeymasterKey(Keymaster& keymaster, const std::string& dir,
Shawn Willden35351812018-01-22 09:08:32 -0700301 const km::AuthorizationSet& keyParams,
302 const km::HardwareAuthToken& authToken,
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800303 const std::string& ciphertext, KeyBuffer* message,
304 bool keepOld) {
Paul Crowleydff8c722016-05-16 08:14:56 -0700305 auto nonce = ciphertext.substr(0, GCM_NONCE_BYTES);
306 auto bodyAndMac = ciphertext.substr(GCM_NONCE_BYTES);
Shawn Willden35351812018-01-22 09:08:32 -0700307 auto opParams = km::AuthorizationSetBuilder().Authorization(km::TAG_NONCE,
308 km::support::blob2hidlVec(nonce));
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800309 auto opHandle = begin(keymaster, dir, km::KeyPurpose::DECRYPT, keyParams, opParams, authToken,
310 nullptr, keepOld);
Paul Crowleydff8c722016-05-16 08:14:56 -0700311 if (!opHandle) return false;
312 if (!opHandle.updateCompletely(bodyAndMac, message)) return false;
313 if (!opHandle.finish(nullptr)) return false;
314 return true;
315}
316
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800317static std::string getStretching(const KeyAuthentication& auth) {
318 if (!auth.usesKeymaster()) {
319 return kStretch_none;
320 } else if (auth.secret.empty()) {
321 return kStretch_nopassword;
322 } else {
323 char paramstr[PROPERTY_VALUE_MAX];
Paul Crowley63c18d32016-02-10 14:02:47 +0000324
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800325 property_get(SCRYPT_PROP, paramstr, SCRYPT_DEFAULTS);
326 return std::string() + kStretchPrefix_scrypt + paramstr;
327 }
Paul Crowley63c18d32016-02-10 14:02:47 +0000328}
329
Paul Crowleydf528a72016-03-09 09:31:37 -0800330static bool stretchingNeedsSalt(const std::string& stretching) {
Paul Crowley63c18d32016-02-10 14:02:47 +0000331 return stretching != kStretch_nopassword && stretching != kStretch_none;
332}
333
Paul Crowleydf528a72016-03-09 09:31:37 -0800334static bool stretchSecret(const std::string& stretching, const std::string& secret,
335 const std::string& salt, std::string* stretched) {
Paul Crowley63c18d32016-02-10 14:02:47 +0000336 if (stretching == kStretch_nopassword) {
337 if (!secret.empty()) {
Paul Crowleyd9b92952016-03-04 13:45:00 -0800338 LOG(WARNING) << "Password present but stretching is nopassword";
Paul Crowley63c18d32016-02-10 14:02:47 +0000339 // Continue anyway
340 }
Paul Crowleya051eb72016-03-08 16:08:32 -0800341 stretched->clear();
Paul Crowley63c18d32016-02-10 14:02:47 +0000342 } else if (stretching == kStretch_none) {
Paul Crowleya051eb72016-03-08 16:08:32 -0800343 *stretched = secret;
Paul Crowleydf528a72016-03-09 09:31:37 -0800344 } else if (std::equal(kStretchPrefix_scrypt.begin(), kStretchPrefix_scrypt.end(),
345 stretching.begin())) {
Paul Crowley63c18d32016-02-10 14:02:47 +0000346 int Nf, rf, pf;
Paul Crowleydf528a72016-03-09 09:31:37 -0800347 if (!parse_scrypt_parameters(stretching.substr(kStretchPrefix_scrypt.size()).c_str(), &Nf,
348 &rf, &pf)) {
Paul Crowley63c18d32016-02-10 14:02:47 +0000349 LOG(ERROR) << "Unable to parse scrypt params in stretching: " << stretching;
350 return false;
351 }
Paul Crowleya051eb72016-03-08 16:08:32 -0800352 stretched->assign(STRETCHED_BYTES, '\0');
Paul Crowleydf528a72016-03-09 09:31:37 -0800353 if (crypto_scrypt(reinterpret_cast<const uint8_t*>(secret.data()), secret.size(),
Shawn Willden785365b2018-01-20 09:37:36 -0700354 reinterpret_cast<const uint8_t*>(salt.data()), salt.size(), 1 << Nf,
355 1 << rf, 1 << pf, reinterpret_cast<uint8_t*>(&(*stretched)[0]),
356 stretched->size()) != 0) {
Paul Crowley63c18d32016-02-10 14:02:47 +0000357 LOG(ERROR) << "scrypt failed with params: " << stretching;
358 return false;
359 }
360 } else {
361 LOG(ERROR) << "Unknown stretching type: " << stretching;
362 return false;
363 }
364 return true;
365}
366
Paul Crowleydf528a72016-03-09 09:31:37 -0800367static bool generateAppId(const KeyAuthentication& auth, const std::string& stretching,
Paul Crowley26a53882017-10-26 11:16:39 -0700368 const std::string& salt, const std::string& secdiscardable_hash,
Paul Crowleydf528a72016-03-09 09:31:37 -0800369 std::string* appId) {
Paul Crowley63c18d32016-02-10 14:02:47 +0000370 std::string stretched;
Paul Crowleya051eb72016-03-08 16:08:32 -0800371 if (!stretchSecret(stretching, auth.secret, salt, &stretched)) return false;
Paul Crowley26a53882017-10-26 11:16:39 -0700372 *appId = secdiscardable_hash + stretched;
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800373 return true;
374}
375
376static void logOpensslError() {
377 LOG(ERROR) << "Openssl error: " << ERR_get_error();
378}
379
Shawn Willden785365b2018-01-20 09:37:36 -0700380static bool encryptWithoutKeymaster(const std::string& preKey, const KeyBuffer& plaintext,
381 std::string* ciphertext) {
Paul Crowley26a53882017-10-26 11:16:39 -0700382 std::string key;
383 hashWithPrefix(kHashPrefix_keygen, preKey, &key);
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800384 key.resize(AES_KEY_BYTES);
385 if (!readRandomBytesOrLog(GCM_NONCE_BYTES, ciphertext)) return false;
386 auto ctx = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>(
387 EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free);
388 if (!ctx) {
389 logOpensslError();
390 return false;
391 }
392 if (1 != EVP_EncryptInit_ex(ctx.get(), EVP_aes_256_gcm(), NULL,
Shawn Willden785365b2018-01-20 09:37:36 -0700393 reinterpret_cast<const uint8_t*>(key.data()),
394 reinterpret_cast<const uint8_t*>(ciphertext->data()))) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800395 logOpensslError();
396 return false;
397 }
398 ciphertext->resize(GCM_NONCE_BYTES + plaintext.size() + GCM_MAC_BYTES);
399 int outlen;
Shawn Willden785365b2018-01-20 09:37:36 -0700400 if (1 != EVP_EncryptUpdate(
401 ctx.get(), reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES),
402 &outlen, reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext.size())) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800403 logOpensslError();
404 return false;
405 }
406 if (outlen != static_cast<int>(plaintext.size())) {
407 LOG(ERROR) << "GCM ciphertext length should be " << plaintext.size() << " was " << outlen;
408 return false;
409 }
Shawn Willden785365b2018-01-20 09:37:36 -0700410 if (1 != EVP_EncryptFinal_ex(
411 ctx.get(),
412 reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES + plaintext.size()),
413 &outlen)) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800414 logOpensslError();
415 return false;
416 }
417 if (outlen != 0) {
418 LOG(ERROR) << "GCM EncryptFinal should be 0, was " << outlen;
419 return false;
420 }
421 if (1 != EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_GET_TAG, GCM_MAC_BYTES,
Shawn Willden785365b2018-01-20 09:37:36 -0700422 reinterpret_cast<uint8_t*>(&(*ciphertext)[0] + GCM_NONCE_BYTES +
423 plaintext.size()))) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800424 logOpensslError();
425 return false;
426 }
427 return true;
428}
429
Shawn Willden785365b2018-01-20 09:37:36 -0700430static bool decryptWithoutKeymaster(const std::string& preKey, const std::string& ciphertext,
431 KeyBuffer* plaintext) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800432 if (ciphertext.size() < GCM_NONCE_BYTES + GCM_MAC_BYTES) {
433 LOG(ERROR) << "GCM ciphertext too small: " << ciphertext.size();
434 return false;
435 }
Paul Crowley26a53882017-10-26 11:16:39 -0700436 std::string key;
437 hashWithPrefix(kHashPrefix_keygen, preKey, &key);
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800438 key.resize(AES_KEY_BYTES);
439 auto ctx = std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)>(
440 EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free);
441 if (!ctx) {
442 logOpensslError();
443 return false;
444 }
445 if (1 != EVP_DecryptInit_ex(ctx.get(), EVP_aes_256_gcm(), NULL,
Shawn Willden785365b2018-01-20 09:37:36 -0700446 reinterpret_cast<const uint8_t*>(key.data()),
447 reinterpret_cast<const uint8_t*>(ciphertext.data()))) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800448 logOpensslError();
449 return false;
450 }
Pavel Grafove2e2d302017-08-01 17:15:53 +0100451 *plaintext = KeyBuffer(ciphertext.size() - GCM_NONCE_BYTES - GCM_MAC_BYTES);
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800452 int outlen;
Shawn Willden785365b2018-01-20 09:37:36 -0700453 if (1 != EVP_DecryptUpdate(ctx.get(), reinterpret_cast<uint8_t*>(&(*plaintext)[0]), &outlen,
454 reinterpret_cast<const uint8_t*>(ciphertext.data() + GCM_NONCE_BYTES),
455 plaintext->size())) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800456 logOpensslError();
457 return false;
458 }
459 if (outlen != static_cast<int>(plaintext->size())) {
460 LOG(ERROR) << "GCM plaintext length should be " << plaintext->size() << " was " << outlen;
461 return false;
462 }
463 if (1 != EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_TAG, GCM_MAC_BYTES,
Shawn Willden785365b2018-01-20 09:37:36 -0700464 const_cast<void*>(reinterpret_cast<const void*>(
465 ciphertext.data() + GCM_NONCE_BYTES + plaintext->size())))) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800466 logOpensslError();
467 return false;
468 }
469 if (1 != EVP_DecryptFinal_ex(ctx.get(),
Shawn Willden785365b2018-01-20 09:37:36 -0700470 reinterpret_cast<uint8_t*>(&(*plaintext)[0] + plaintext->size()),
471 &outlen)) {
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800472 logOpensslError();
473 return false;
474 }
475 if (outlen != 0) {
476 LOG(ERROR) << "GCM EncryptFinal should be 0, was " << outlen;
477 return false;
478 }
Paul Crowley63c18d32016-02-10 14:02:47 +0000479 return true;
Paul Crowley05720802016-02-08 15:55:41 +0000480}
481
Paul Crowleyf71ace32016-06-02 11:01:19 -0700482bool pathExists(const std::string& path) {
483 return access(path.c_str(), F_OK) == 0;
484}
485
Pavel Grafove2e2d302017-08-01 17:15:53 +0100486bool storeKey(const std::string& dir, const KeyAuthentication& auth, const KeyBuffer& key) {
Paul Crowley1ef25582016-01-21 20:26:12 +0000487 if (TEMP_FAILURE_RETRY(mkdir(dir.c_str(), 0700)) == -1) {
488 PLOG(ERROR) << "key mkdir " << dir;
489 return false;
490 }
Paul Crowleydf528a72016-03-09 09:31:37 -0800491 if (!writeStringToFile(kCurrentVersion, dir + "/" + kFn_version)) return false;
Paul Crowley26a53882017-10-26 11:16:39 -0700492 std::string secdiscardable_hash;
493 if (!createSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false;
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800494 std::string stretching = getStretching(auth);
Paul Crowleydf528a72016-03-09 09:31:37 -0800495 if (!writeStringToFile(stretching, dir + "/" + kFn_stretching)) return false;
Paul Crowley63c18d32016-02-10 14:02:47 +0000496 std::string salt;
497 if (stretchingNeedsSalt(stretching)) {
498 if (ReadRandomBytes(SALT_BYTES, salt) != OK) {
499 LOG(ERROR) << "Random read failed";
500 return false;
501 }
Paul Crowleydf528a72016-03-09 09:31:37 -0800502 if (!writeStringToFile(salt, dir + "/" + kFn_salt)) return false;
Paul Crowley63c18d32016-02-10 14:02:47 +0000503 }
Paul Crowley320e5e12016-03-04 14:07:05 -0800504 std::string appId;
Paul Crowley26a53882017-10-26 11:16:39 -0700505 if (!generateAppId(auth, stretching, salt, secdiscardable_hash, &appId)) return false;
Paul Crowley320e5e12016-03-04 14:07:05 -0800506 std::string encryptedKey;
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800507 if (auth.usesKeymaster()) {
508 Keymaster keymaster;
509 if (!keymaster) return false;
510 std::string kmKey;
511 if (!generateKeymasterKey(keymaster, auth, appId, &kmKey)) return false;
512 if (!writeStringToFile(kmKey, dir + "/" + kFn_keymaster_key_blob)) return false;
Shawn Willden35351812018-01-22 09:08:32 -0700513 km::AuthorizationSet keyParams;
514 km::HardwareAuthToken authToken;
515 std::tie(keyParams, authToken) = beginParams(auth, appId);
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800516 if (!encryptWithKeymasterKey(keymaster, dir, keyParams, authToken, key, &encryptedKey,
517 false))
Shawn Willden35351812018-01-22 09:08:32 -0700518 return false;
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800519 } else {
520 if (!encryptWithoutKeymaster(appId, key, &encryptedKey)) return false;
521 }
Paul Crowley13ffd8e2016-01-27 14:30:22 +0000522 if (!writeStringToFile(encryptedKey, dir + "/" + kFn_encrypted_key)) return false;
Paul Crowley621d9b92018-12-07 15:36:09 -0800523 if (!FsyncDirectory(dir)) return false;
Paul Crowley1ef25582016-01-21 20:26:12 +0000524 return true;
525}
526
Paul Crowleyf71ace32016-06-02 11:01:19 -0700527bool storeKeyAtomically(const std::string& key_path, const std::string& tmp_path,
Pavel Grafove2e2d302017-08-01 17:15:53 +0100528 const KeyAuthentication& auth, const KeyBuffer& key) {
Paul Crowleyf71ace32016-06-02 11:01:19 -0700529 if (pathExists(key_path)) {
530 LOG(ERROR) << "Already exists, cannot create key at: " << key_path;
531 return false;
532 }
533 if (pathExists(tmp_path)) {
534 LOG(DEBUG) << "Already exists, destroying: " << tmp_path;
535 destroyKey(tmp_path); // May be partially created so ignore errors
536 }
537 if (!storeKey(tmp_path, auth, key)) return false;
538 if (rename(tmp_path.c_str(), key_path.c_str()) != 0) {
539 PLOG(ERROR) << "Unable to move new key to location: " << key_path;
540 return false;
541 }
542 LOG(DEBUG) << "Created key: " << key_path;
543 return true;
544}
545
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800546bool retrieveKey(const std::string& dir, const KeyAuthentication& auth, KeyBuffer* key,
547 bool keepOld) {
Paul Crowley05720802016-02-08 15:55:41 +0000548 std::string version;
Paul Crowleya051eb72016-03-08 16:08:32 -0800549 if (!readFileToString(dir + "/" + kFn_version, &version)) return false;
Paul Crowley05720802016-02-08 15:55:41 +0000550 if (version != kCurrentVersion) {
551 LOG(ERROR) << "Version mismatch, expected " << kCurrentVersion << " got " << version;
552 return false;
553 }
Paul Crowley26a53882017-10-26 11:16:39 -0700554 std::string secdiscardable_hash;
555 if (!readSecdiscardable(dir + "/" + kFn_secdiscardable, &secdiscardable_hash)) return false;
Paul Crowley63c18d32016-02-10 14:02:47 +0000556 std::string stretching;
Paul Crowleya051eb72016-03-08 16:08:32 -0800557 if (!readFileToString(dir + "/" + kFn_stretching, &stretching)) return false;
Paul Crowley63c18d32016-02-10 14:02:47 +0000558 std::string salt;
559 if (stretchingNeedsSalt(stretching)) {
Paul Crowleydf528a72016-03-09 09:31:37 -0800560 if (!readFileToString(dir + "/" + kFn_salt, &salt)) return false;
Paul Crowley63c18d32016-02-10 14:02:47 +0000561 }
Paul Crowley320e5e12016-03-04 14:07:05 -0800562 std::string appId;
Paul Crowley26a53882017-10-26 11:16:39 -0700563 if (!generateAppId(auth, stretching, salt, secdiscardable_hash, &appId)) return false;
Paul Crowley13ffd8e2016-01-27 14:30:22 +0000564 std::string encryptedMessage;
Paul Crowleya051eb72016-03-08 16:08:32 -0800565 if (!readFileToString(dir + "/" + kFn_encrypted_key, &encryptedMessage)) return false;
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800566 if (auth.usesKeymaster()) {
567 Keymaster keymaster;
568 if (!keymaster) return false;
Shawn Willden35351812018-01-22 09:08:32 -0700569 km::AuthorizationSet keyParams;
570 km::HardwareAuthToken authToken;
571 std::tie(keyParams, authToken) = beginParams(auth, appId);
Daniel Rosenberg690d6de2018-12-14 01:08:10 -0800572 if (!decryptWithKeymasterKey(keymaster, dir, keyParams, authToken, encryptedMessage, key,
573 keepOld))
Shawn Willden785365b2018-01-20 09:37:36 -0700574 return false;
Paul Crowley6ab2cab2017-01-04 22:32:40 -0800575 } else {
576 if (!decryptWithoutKeymaster(appId, encryptedMessage, key)) return false;
577 }
578 return true;
Paul Crowley1ef25582016-01-21 20:26:12 +0000579}
580
Paul Crowleydf528a72016-03-09 09:31:37 -0800581static bool deleteKey(const std::string& dir) {
Paul Crowley13ffd8e2016-01-27 14:30:22 +0000582 std::string kmKey;
Paul Crowleya051eb72016-03-08 16:08:32 -0800583 if (!readFileToString(dir + "/" + kFn_keymaster_key_blob, &kmKey)) return false;
Paul Crowley1ef25582016-01-21 20:26:12 +0000584 Keymaster keymaster;
585 if (!keymaster) return false;
Paul Crowley13ffd8e2016-01-27 14:30:22 +0000586 if (!keymaster.deleteKey(kmKey)) return false;
Paul Crowley1ef25582016-01-21 20:26:12 +0000587 return true;
588}
589
Rubin Xu2436e272017-04-27 20:43:10 +0100590bool runSecdiscardSingle(const std::string& file) {
Shawn Willden785365b2018-01-20 09:37:36 -0700591 if (ForkExecvp(std::vector<std::string>{kSecdiscardPath, "--", file}) != 0) {
Rubin Xu2436e272017-04-27 20:43:10 +0100592 LOG(ERROR) << "secdiscard failed";
593 return false;
594 }
595 return true;
596}
597
Paul Crowleydf528a72016-03-09 09:31:37 -0800598static bool recursiveDeleteKey(const std::string& dir) {
599 if (ForkExecvp(std::vector<std::string>{kRmPath, "-rf", dir}) != 0) {
Paul Crowley1ef25582016-01-21 20:26:12 +0000600 LOG(ERROR) << "recursive delete failed";
601 return false;
602 }
603 return true;
604}
605
Paul Crowleydf528a72016-03-09 09:31:37 -0800606bool destroyKey(const std::string& dir) {
Paul Crowley1ef25582016-01-21 20:26:12 +0000607 bool success = true;
608 // Try each thing, even if previous things failed.
Paul Crowleyff19b052017-10-26 11:28:55 -0700609 bool uses_km = pathExists(dir + "/" + kFn_keymaster_key_blob);
610 if (uses_km) {
611 success &= deleteKey(dir);
612 }
613 auto secdiscard_cmd = std::vector<std::string>{
Paul Crowley14c8c072018-09-18 13:30:21 -0700614 kSecdiscardPath,
615 "--",
616 dir + "/" + kFn_encrypted_key,
617 dir + "/" + kFn_secdiscardable,
Paul Crowleyff19b052017-10-26 11:28:55 -0700618 };
619 if (uses_km) {
620 secdiscard_cmd.emplace_back(dir + "/" + kFn_keymaster_key_blob);
621 }
622 if (ForkExecvp(secdiscard_cmd) != 0) {
623 LOG(ERROR) << "secdiscard failed";
624 success = false;
625 }
Paul Crowley13ffd8e2016-01-27 14:30:22 +0000626 success &= recursiveDeleteKey(dir);
Paul Crowley1ef25582016-01-21 20:26:12 +0000627 return success;
628}
629
630} // namespace vold
631} // namespace android