1 /* 2 * Copyright (C) 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 #include <memory> 18 #include <mutex> 19 #include <vector> 20 21 #include <keystore/keymaster_types.h> 22 23 #ifndef KEYSTORE_AUTH_TOKEN_TABLE_H_ 24 #define KEYSTORE_AUTH_TOKEN_TABLE_H_ 25 26 namespace keystore { 27 28 using keymaster::HardwareAuthToken; 29 30 namespace test { 31 class AuthTokenTableTest; 32 } // namespace test 33 34 time_t clock_gettime_raw(); 35 36 /** 37 * AuthTokenTable manages a set of received authorization tokens and can provide the appropriate 38 * token for authorizing a key operation. 39 * 40 * To keep the table from growing without bound, superseded entries are removed when possible, and 41 * least recently used entries are automatically pruned when when the table exceeds a size limit, 42 * which is expected to be relatively small, since the implementation uses a linear search. 43 */ 44 class AuthTokenTable { 45 public: 46 explicit AuthTokenTable(size_t max_entries = 32, time_t (*clock_function)() = clock_gettime_raw) max_entries_(max_entries)47 : max_entries_(max_entries), last_off_body_(clock_function()), 48 clock_function_(clock_function) {} 49 50 enum Error { 51 OK, 52 AUTH_NOT_REQUIRED = -1, 53 AUTH_TOKEN_EXPIRED = -2, // Found a matching token, but it's too old. 54 AUTH_TOKEN_WRONG_SID = -3, // Found a token with the right challenge, but wrong SID. This 55 // most likely indicates that the authenticator was updated 56 // (e.g. new fingerprint enrolled). 57 OP_HANDLE_REQUIRED = -4, // The key requires auth per use but op_handle was zero. 58 AUTH_TOKEN_NOT_FOUND = -5, 59 }; 60 61 /** 62 * Add an authorization token to the table. 63 */ 64 void AddAuthenticationToken(HardwareAuthToken&& auth_token); 65 66 /** 67 * Find an authorization token that authorizes the operation specified by \p operation_handle on 68 * a key with the characteristics specified in \p key_info. 69 * 70 * This method is O(n * m), where n is the number of KM_TAG_USER_SECURE_ID entries in key_info 71 * and m is the number of entries in the table. It could be made better, but n and m should 72 * always be small. 73 * 74 * The table retains ownership of the returned object. 75 */ 76 std::tuple<Error, HardwareAuthToken> FindAuthorization(const AuthorizationSet& key_info, 77 KeyPurpose purpose, uint64_t op_handle); 78 79 /** 80 * Mark operation completed. This allows tokens associated with the specified operation to be 81 * superseded by new tokens. 82 */ 83 void MarkCompleted(const uint64_t op_handle); 84 85 /** 86 * Update the last_off_body_ timestamp so that tokens which remain authorized only so long as 87 * the device stays on body can be revoked. 88 */ 89 void onDeviceOffBody(); 90 91 void Clear(); 92 93 /** 94 * This function shall only be used for testing. 95 * 96 * BEWARE: Since the auth token table can be accessed 97 * concurrently, the size may be out dated as soon as it returns. 98 */ 99 size_t size() const; 100 101 private: 102 friend class AuthTokenTableTest; 103 104 class Entry { 105 public: 106 Entry(HardwareAuthToken&& token, time_t current_time); Entry(Entry && entry)107 Entry(Entry&& entry) noexcept { *this = std::move(entry); } 108 109 void operator=(Entry&& rhs) noexcept { 110 token_ = std::move(rhs.token_); 111 time_received_ = rhs.time_received_; 112 last_use_ = rhs.last_use_; 113 operation_completed_ = rhs.operation_completed_; 114 } 115 116 bool operator<(const Entry& rhs) const { return last_use_ < rhs.last_use_; } 117 118 void UpdateLastUse(time_t time); 119 120 bool Supersedes(const Entry& entry) const; 121 bool SatisfiesAuth(const std::vector<uint64_t>& sids, HardwareAuthenticatorType auth_type); 122 is_newer_than(const Entry * entry)123 bool is_newer_than(const Entry* entry) const { 124 if (!entry) return true; 125 uint64_t ts = token_.timestamp; 126 uint64_t other_ts = entry->token_.timestamp; 127 // Normally comparing timestamp_host_order alone is sufficient, but here is an 128 // additional hack to compare time_received value for some devices where their auth 129 // tokens contain fixed timestamp (due to the a stuck secure RTC on them) 130 return (ts > other_ts) || 131 ((ts == other_ts) && (time_received_ > entry->time_received_)); 132 } 133 mark_completed()134 void mark_completed() { operation_completed_ = true; } 135 token()136 const HardwareAuthToken& token() const & { return token_; } time_received()137 time_t time_received() const { return time_received_; } completed()138 bool completed() const { return operation_completed_; } 139 140 private: SatisfiesAuth(uint64_t sid,HardwareAuthenticatorType auth_type)141 bool SatisfiesAuth(uint64_t sid, HardwareAuthenticatorType auth_type) const { 142 return (sid == token_.userId || sid == token_.authenticatorId) && 143 (auth_type & token_.authenticatorType) != 0; 144 } 145 146 HardwareAuthToken token_; 147 time_t time_received_; 148 time_t last_use_; 149 bool operation_completed_; 150 }; 151 152 std::tuple<Error, HardwareAuthToken> 153 FindAuthPerOpAuthorization(const std::vector<uint64_t>& sids, 154 HardwareAuthenticatorType auth_type, uint64_t op_handle); 155 std::tuple<Error, HardwareAuthToken> FindTimedAuthorization(const std::vector<uint64_t>& sids, 156 HardwareAuthenticatorType auth_type, 157 const AuthorizationSet& key_info); 158 void ExtractSids(const AuthorizationSet& key_info, std::vector<uint64_t>* sids); 159 void RemoveEntriesSupersededBy(const Entry& entry); 160 bool IsSupersededBySomeEntry(const Entry& entry); 161 162 /** 163 * Guards the entries_ vector against concurrent modification. All public facing methods 164 * reading of modifying the vector must grab this mutex. 165 */ 166 mutable std::mutex entries_mutex_; 167 std::vector<Entry> entries_; 168 size_t max_entries_; 169 time_t last_off_body_; 170 time_t (*clock_function_)(); 171 }; 172 173 } // namespace keystore 174 175 #endif // KEYSTORE_AUTH_TOKEN_TABLE_H_ 176