1 /* 2 * Copyright 2015 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 18 #pragma once 19 20 extern "C" { 21 #include <openssl/rand.h> 22 #include <openssl/sha.h> 23 24 #include <crypto_scrypt.h> 25 } 26 27 #include <android-base/memory.h> 28 #include <gatekeeper/gatekeeper.h> 29 30 #include <iostream> 31 #include <memory> 32 #include <unordered_map> 33 34 namespace gatekeeper { 35 36 struct fast_hash_t { 37 uint64_t salt; 38 uint8_t digest[SHA256_DIGEST_LENGTH]; 39 }; 40 41 class SoftGateKeeper : public GateKeeper { 42 public: 43 static const uint32_t SIGNATURE_LENGTH_BYTES = 32; 44 45 // scrypt params 46 static const uint64_t N = 16384; 47 static const uint32_t r = 8; 48 static const uint32_t p = 1; 49 50 static const int MAX_UINT_32_CHARS = 11; 51 SoftGateKeeper()52 SoftGateKeeper() { 53 key_.reset(new uint8_t[SIGNATURE_LENGTH_BYTES]); 54 memset(key_.get(), 0, SIGNATURE_LENGTH_BYTES); 55 } 56 ~SoftGateKeeper()57 virtual ~SoftGateKeeper() {} 58 GetAuthTokenKey(const uint8_t ** auth_token_key,uint32_t * length)59 virtual bool GetAuthTokenKey(const uint8_t** auth_token_key, uint32_t* length) const { 60 if (auth_token_key == NULL || length == NULL) return false; 61 *auth_token_key = key_.get(); 62 *length = SIGNATURE_LENGTH_BYTES; 63 return true; 64 } 65 GetPasswordKey(const uint8_t ** password_key,uint32_t * length)66 virtual void GetPasswordKey(const uint8_t** password_key, uint32_t* length) { 67 if (password_key == NULL || length == NULL) return; 68 *password_key = key_.get(); 69 *length = SIGNATURE_LENGTH_BYTES; 70 } 71 ComputePasswordSignature(uint8_t * signature,uint32_t signature_length,const uint8_t *,uint32_t,const uint8_t * password,uint32_t password_length,salt_t salt)72 virtual void ComputePasswordSignature(uint8_t* signature, uint32_t signature_length, 73 const uint8_t*, uint32_t, const uint8_t* password, 74 uint32_t password_length, salt_t salt) const { 75 if (signature == NULL) return; 76 crypto_scrypt(password, password_length, reinterpret_cast<uint8_t*>(&salt), sizeof(salt), N, 77 r, p, signature, signature_length); 78 } 79 GetRandom(void * random,uint32_t requested_length)80 virtual void GetRandom(void* random, uint32_t requested_length) const { 81 if (random == NULL) return; 82 RAND_pseudo_bytes((uint8_t*)random, requested_length); 83 } 84 ComputeSignature(uint8_t * signature,uint32_t signature_length,const uint8_t *,uint32_t,const uint8_t *,const uint32_t)85 virtual void ComputeSignature(uint8_t* signature, uint32_t signature_length, const uint8_t*, 86 uint32_t, const uint8_t*, const uint32_t) const { 87 if (signature == NULL) return; 88 memset(signature, 0, signature_length); 89 } 90 GetMillisecondsSinceBoot()91 virtual uint64_t GetMillisecondsSinceBoot() const { 92 #ifdef _WIN32 93 return GetTickCount64(); 94 #else 95 struct timespec time; 96 int res = clock_gettime(CLOCK_BOOTTIME, &time); 97 if (res < 0) return 0; 98 return (time.tv_sec * 1000) + (time.tv_nsec / 1000 / 1000); 99 #endif 100 } 101 IsHardwareBacked()102 virtual bool IsHardwareBacked() const { return false; } 103 GetFailureRecord(uint32_t uid,secure_id_t user_id,failure_record_t * record,bool)104 virtual bool GetFailureRecord(uint32_t uid, secure_id_t user_id, failure_record_t* record, 105 bool /* secure */) { 106 failure_record_t* stored = &failure_map_[uid]; 107 if (user_id != stored->secure_user_id) { 108 stored->secure_user_id = user_id; 109 stored->last_checked_timestamp = 0; 110 stored->failure_counter = 0; 111 } 112 memcpy(record, stored, sizeof(*record)); 113 return true; 114 } 115 ClearFailureRecord(uint32_t uid,secure_id_t user_id,bool)116 virtual bool ClearFailureRecord(uint32_t uid, secure_id_t user_id, bool /* secure */) { 117 failure_record_t* stored = &failure_map_[uid]; 118 stored->secure_user_id = user_id; 119 stored->last_checked_timestamp = 0; 120 stored->failure_counter = 0; 121 return true; 122 } 123 WriteFailureRecord(uint32_t uid,failure_record_t * record,bool)124 virtual bool WriteFailureRecord(uint32_t uid, failure_record_t* record, bool /* secure */) { 125 failure_map_[uid] = *record; 126 return true; 127 } 128 ComputeFastHash(const SizedBuffer & password,uint64_t salt)129 fast_hash_t ComputeFastHash(const SizedBuffer& password, uint64_t salt) { 130 fast_hash_t fast_hash; 131 size_t digest_size = password.size() + sizeof(salt); 132 std::unique_ptr<uint8_t[]> digest(new uint8_t[digest_size]); 133 memcpy(digest.get(), &salt, sizeof(salt)); 134 memcpy(digest.get() + sizeof(salt), password.Data<uint8_t>(), password.size()); 135 136 SHA256(digest.get(), digest_size, (uint8_t*)&fast_hash.digest); 137 138 fast_hash.salt = salt; 139 return fast_hash; 140 } 141 VerifyFast(const fast_hash_t & fast_hash,const SizedBuffer & password)142 bool VerifyFast(const fast_hash_t& fast_hash, const SizedBuffer& password) { 143 fast_hash_t computed = ComputeFastHash(password, fast_hash.salt); 144 return memcmp(computed.digest, fast_hash.digest, SHA256_DIGEST_LENGTH) == 0; 145 } 146 DoVerify(const password_handle_t * expected_handle,const SizedBuffer & password)147 bool DoVerify(const password_handle_t* expected_handle, const SizedBuffer& password) { 148 uint64_t user_id = android::base::get_unaligned<secure_id_t>(&expected_handle->user_id); 149 FastHashMap::const_iterator it = fast_hash_map_.find(user_id); 150 if (it != fast_hash_map_.end() && VerifyFast(it->second, password)) { 151 return true; 152 } else { 153 if (GateKeeper::DoVerify(expected_handle, password)) { 154 uint64_t salt; 155 GetRandom(&salt, sizeof(salt)); 156 fast_hash_map_[user_id] = ComputeFastHash(password, salt); 157 return true; 158 } 159 } 160 161 return false; 162 } 163 164 private: 165 typedef std::unordered_map<uint32_t, failure_record_t> FailureRecordMap; 166 typedef std::unordered_map<uint64_t, fast_hash_t> FastHashMap; 167 168 std::unique_ptr<uint8_t[]> key_; 169 FailureRecordMap failure_map_; 170 FastHashMap fast_hash_map_; 171 }; 172 } // namespace gatekeeper 173