Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 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 | |
Ken Chen | 5471dca | 2019-04-15 15:25:35 +0800 | [diff] [blame] | 17 | #define LOG_TAG "resolv" |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 18 | |
Mike Yu | 303b0df | 2018-12-24 17:05:02 +0800 | [diff] [blame] | 19 | #include "PrivateDnsConfiguration.h" |
| 20 | |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 21 | #include <android-base/logging.h> |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 22 | #include <netdb.h> |
| 23 | #include <sys/socket.h> |
| 24 | |
Bernie Innocenti | ec4219b | 2019-01-30 11:16:36 +0900 | [diff] [blame] | 25 | #include "DnsTlsTransport.h" |
Mike Yu | 303b0df | 2018-12-24 17:05:02 +0800 | [diff] [blame] | 26 | #include "ResolverEventReporter.h" |
Bernie Innocenti | ec4219b | 2019-01-30 11:16:36 +0900 | [diff] [blame] | 27 | #include "netd_resolv/resolv.h" |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 28 | #include "netdutils/BackoffSequence.h" |
| 29 | |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 30 | namespace android { |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 31 | namespace net { |
| 32 | |
| 33 | std::string addrToString(const sockaddr_storage* addr) { |
| 34 | char out[INET6_ADDRSTRLEN] = {0}; |
| 35 | getnameinfo((const sockaddr*) addr, sizeof(sockaddr_storage), out, INET6_ADDRSTRLEN, nullptr, 0, |
| 36 | NI_NUMERICHOST); |
| 37 | return std::string(out); |
| 38 | } |
| 39 | |
| 40 | bool parseServer(const char* server, sockaddr_storage* parsed) { |
| 41 | addrinfo hints = {.ai_family = AF_UNSPEC, .ai_flags = AI_NUMERICHOST | AI_NUMERICSERV}; |
| 42 | addrinfo* res; |
| 43 | |
| 44 | int err = getaddrinfo(server, "853", &hints, &res); |
| 45 | if (err != 0) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 46 | LOG(WARNING) << "Failed to parse server address (" << server << "): " << gai_strerror(err); |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 47 | return false; |
| 48 | } |
| 49 | |
| 50 | memcpy(parsed, res->ai_addr, res->ai_addrlen); |
| 51 | freeaddrinfo(res); |
| 52 | return true; |
| 53 | } |
| 54 | |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 55 | int PrivateDnsConfiguration::set(int32_t netId, uint32_t mark, |
| 56 | const std::vector<std::string>& servers, const std::string& name, |
| 57 | const std::set<std::vector<uint8_t>>& fingerprints) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 58 | LOG(VERBOSE) << "PrivateDnsConfiguration::set(" << netId << ", " << mark << ", " |
| 59 | << servers.size() << ", " << name << ", " << fingerprints.size() << ")"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 60 | |
| 61 | const bool explicitlyConfigured = !name.empty() || !fingerprints.empty(); |
| 62 | |
| 63 | // Parse the list of servers that has been passed in |
| 64 | std::set<DnsTlsServer> tlsServers; |
| 65 | for (size_t i = 0; i < servers.size(); ++i) { |
| 66 | sockaddr_storage parsed; |
| 67 | if (!parseServer(servers[i].c_str(), &parsed)) { |
| 68 | return -EINVAL; |
| 69 | } |
| 70 | DnsTlsServer server(parsed); |
| 71 | server.name = name; |
| 72 | server.fingerprints = fingerprints; |
| 73 | tlsServers.insert(server); |
| 74 | } |
| 75 | |
| 76 | std::lock_guard guard(mPrivateDnsLock); |
| 77 | if (explicitlyConfigured) { |
| 78 | mPrivateDnsModes[netId] = PrivateDnsMode::STRICT; |
| 79 | } else if (!tlsServers.empty()) { |
| 80 | mPrivateDnsModes[netId] = PrivateDnsMode::OPPORTUNISTIC; |
| 81 | } else { |
| 82 | mPrivateDnsModes[netId] = PrivateDnsMode::OFF; |
| 83 | mPrivateDnsTransports.erase(netId); |
| 84 | return 0; |
| 85 | } |
| 86 | |
| 87 | // Create the tracker if it was not present |
| 88 | auto netPair = mPrivateDnsTransports.find(netId); |
| 89 | if (netPair == mPrivateDnsTransports.end()) { |
| 90 | // No TLS tracker yet for this netId. |
| 91 | bool added; |
| 92 | std::tie(netPair, added) = mPrivateDnsTransports.emplace(netId, PrivateDnsTracker()); |
| 93 | if (!added) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 94 | LOG(ERROR) << "Memory error while recording private DNS for netId " << netId; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 95 | return -ENOMEM; |
| 96 | } |
| 97 | } |
| 98 | auto& tracker = netPair->second; |
| 99 | |
| 100 | // Remove any servers from the tracker that are not in |servers| exactly. |
| 101 | for (auto it = tracker.begin(); it != tracker.end();) { |
| 102 | if (tlsServers.count(it->first) == 0) { |
| 103 | it = tracker.erase(it); |
| 104 | } else { |
| 105 | ++it; |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | // Add any new or changed servers to the tracker, and initiate async checks for them. |
| 110 | for (const auto& server : tlsServers) { |
| 111 | if (needsValidation(tracker, server)) { |
| 112 | validatePrivateDnsProvider(server, tracker, netId, mark); |
| 113 | } |
| 114 | } |
| 115 | return 0; |
| 116 | } |
| 117 | |
| 118 | PrivateDnsStatus PrivateDnsConfiguration::getStatus(unsigned netId) { |
| 119 | PrivateDnsStatus status{PrivateDnsMode::OFF, {}}; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 120 | std::lock_guard guard(mPrivateDnsLock); |
| 121 | |
| 122 | const auto mode = mPrivateDnsModes.find(netId); |
| 123 | if (mode == mPrivateDnsModes.end()) return status; |
| 124 | status.mode = mode->second; |
| 125 | |
| 126 | const auto netPair = mPrivateDnsTransports.find(netId); |
| 127 | if (netPair != mPrivateDnsTransports.end()) { |
| 128 | for (const auto& serverPair : netPair->second) { |
| 129 | if (serverPair.second == Validation::success) { |
| 130 | status.validatedServers.push_back(serverPair.first); |
| 131 | } |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | return status; |
| 136 | } |
| 137 | |
| 138 | void PrivateDnsConfiguration::getStatus(unsigned netId, ExternalPrivateDnsStatus* status) { |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 139 | std::lock_guard guard(mPrivateDnsLock); |
| 140 | |
| 141 | const auto mode = mPrivateDnsModes.find(netId); |
| 142 | if (mode == mPrivateDnsModes.end()) return; |
| 143 | status->mode = mode->second; |
| 144 | |
| 145 | const auto netPair = mPrivateDnsTransports.find(netId); |
| 146 | if (netPair != mPrivateDnsTransports.end()) { |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 147 | int count = 0; |
| 148 | for (const auto& serverPair : netPair->second) { |
| 149 | status->serverStatus[count].ss = serverPair.first.ss; |
| 150 | status->serverStatus[count].hostname = |
| 151 | serverPair.first.name.empty() ? "" : serverPair.first.name.c_str(); |
| 152 | status->serverStatus[count].validation = serverPair.second; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 153 | count++; |
Bernie Innocenti | 4c2a461 | 2018-11-20 19:23:56 +0900 | [diff] [blame] | 154 | if (count >= MAXNS) break; // Lose the rest |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 155 | } |
Bernie Innocenti | 9339022 | 2019-01-10 18:33:45 +0900 | [diff] [blame] | 156 | status->numServers = count; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 157 | } |
| 158 | } |
| 159 | |
| 160 | void PrivateDnsConfiguration::clear(unsigned netId) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 161 | LOG(DEBUG) << "PrivateDnsConfiguration::clear(" << netId << ")"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 162 | std::lock_guard guard(mPrivateDnsLock); |
| 163 | mPrivateDnsModes.erase(netId); |
| 164 | mPrivateDnsTransports.erase(netId); |
| 165 | } |
| 166 | |
| 167 | void PrivateDnsConfiguration::validatePrivateDnsProvider(const DnsTlsServer& server, |
| 168 | PrivateDnsTracker& tracker, unsigned netId, |
| 169 | uint32_t mark) REQUIRES(mPrivateDnsLock) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 170 | LOG(VERBOSE) << "validatePrivateDnsProvider(" << addrToString(&server.ss) << ", " << netId |
| 171 | << ")"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 172 | |
| 173 | tracker[server] = Validation::in_process; |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 174 | LOG(VERBOSE) << "Server " << addrToString(&server.ss) |
| 175 | << " marked as in_process. Tracker now has size " << tracker.size(); |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 176 | // Note that capturing |server| and |netId| in this lambda create copies. |
| 177 | std::thread validate_thread([this, server, netId, mark] { |
| 178 | // cat /proc/sys/net/ipv4/tcp_syn_retries yields "6". |
| 179 | // |
| 180 | // Start with a 1 minute delay and backoff to once per hour. |
| 181 | // |
| 182 | // Assumptions: |
| 183 | // [1] Each TLS validation is ~10KB of certs+handshake+payload. |
| 184 | // [2] Network typically provision clients with <=4 nameservers. |
| 185 | // [3] Average month has 30 days. |
| 186 | // |
| 187 | // Each validation pass in a given hour is ~1.2MB of data. And 24 |
| 188 | // such validation passes per day is about ~30MB per month, in the |
| 189 | // worst case. Otherwise, this will cost ~600 SYNs per month |
| 190 | // (6 SYNs per ip, 4 ips per validation pass, 24 passes per day). |
Bernie Innocenti | 23c6e2a | 2019-05-16 15:18:35 +0900 | [diff] [blame] | 191 | auto backoff = netdutils::BackoffSequence<>::Builder() |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 192 | .withInitialRetransmissionTime(std::chrono::seconds(60)) |
| 193 | .withMaximumRetransmissionTime(std::chrono::seconds(3600)) |
| 194 | .build(); |
| 195 | |
| 196 | while (true) { |
| 197 | // ::validate() is a blocking call that performs network operations. |
| 198 | // It can take milliseconds to minutes, up to the SYN retry limit. |
| 199 | const bool success = DnsTlsTransport::validate(server, netId, mark); |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 200 | LOG(VERBOSE) << "validateDnsTlsServer returned " << success << " for " |
| 201 | << addrToString(&server.ss); |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 202 | |
| 203 | const bool needs_reeval = this->recordPrivateDnsValidation(server, netId, success); |
| 204 | if (!needs_reeval) { |
| 205 | break; |
| 206 | } |
| 207 | |
| 208 | if (backoff.hasNextTimeout()) { |
| 209 | std::this_thread::sleep_for(backoff.getNextTimeout()); |
| 210 | } else { |
| 211 | break; |
| 212 | } |
| 213 | } |
| 214 | }); |
| 215 | validate_thread.detach(); |
| 216 | } |
| 217 | |
| 218 | bool PrivateDnsConfiguration::recordPrivateDnsValidation(const DnsTlsServer& server, unsigned netId, |
| 219 | bool success) { |
| 220 | constexpr bool NEEDS_REEVALUATION = true; |
| 221 | constexpr bool DONT_REEVALUATE = false; |
| 222 | |
| 223 | std::lock_guard guard(mPrivateDnsLock); |
| 224 | |
| 225 | auto netPair = mPrivateDnsTransports.find(netId); |
| 226 | if (netPair == mPrivateDnsTransports.end()) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 227 | LOG(WARNING) << "netId " << netId << " was erased during private DNS validation"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 228 | return DONT_REEVALUATE; |
| 229 | } |
| 230 | |
| 231 | const auto mode = mPrivateDnsModes.find(netId); |
| 232 | if (mode == mPrivateDnsModes.end()) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 233 | LOG(WARNING) << "netId " << netId << " has no private DNS validation mode"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 234 | return DONT_REEVALUATE; |
| 235 | } |
| 236 | const bool modeDoesReevaluation = (mode->second == PrivateDnsMode::STRICT); |
| 237 | |
| 238 | bool reevaluationStatus = |
| 239 | (success || !modeDoesReevaluation) ? DONT_REEVALUATE : NEEDS_REEVALUATION; |
| 240 | |
| 241 | auto& tracker = netPair->second; |
| 242 | auto serverPair = tracker.find(server); |
| 243 | if (serverPair == tracker.end()) { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 244 | LOG(WARNING) << "Server " << addrToString(&server.ss) |
| 245 | << " was removed during private DNS validation"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 246 | success = false; |
| 247 | reevaluationStatus = DONT_REEVALUATE; |
| 248 | } else if (!(serverPair->first == server)) { |
| 249 | // TODO: It doesn't seem correct to overwrite the tracker entry for |
| 250 | // |server| down below in this circumstance... Fix this. |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 251 | LOG(WARNING) << "Server " << addrToString(&server.ss) |
| 252 | << " was changed during private DNS validation"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 253 | success = false; |
| 254 | reevaluationStatus = DONT_REEVALUATE; |
| 255 | } |
| 256 | |
Mike Yu | 303b0df | 2018-12-24 17:05:02 +0800 | [diff] [blame] | 257 | // Send a validation event to NetdEventListenerService. |
Hungming Chen | a32c8c1 | 2019-01-25 10:47:40 +0800 | [diff] [blame] | 258 | const auto& listeners = ResolverEventReporter::getInstance().getListeners(); |
| 259 | if (listeners.size() != 0) { |
| 260 | for (const auto& it : listeners) { |
| 261 | it->onPrivateDnsValidationEvent(netId, addrToString(&server.ss), server.name, success); |
| 262 | } |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 263 | LOG(VERBOSE) << "Sent validation " << (success ? "success" : "failure") |
| 264 | << " event on netId " << netId << " for " << addrToString(&server.ss) |
| 265 | << " with hostname " << server.name; |
Mike Yu | 303b0df | 2018-12-24 17:05:02 +0800 | [diff] [blame] | 266 | } else { |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 267 | LOG(ERROR) |
| 268 | << "Validation event not sent since no INetdEventListener receiver is available."; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 269 | } |
| 270 | |
| 271 | if (success) { |
| 272 | tracker[server] = Validation::success; |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 273 | LOG(VERBOSE) << "Validation succeeded for " << addrToString(&server.ss) |
| 274 | << "! Tracker now has " << tracker.size() << " entries."; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 275 | } else { |
| 276 | // Validation failure is expected if a user is on a captive portal. |
| 277 | // TODO: Trigger a second validation attempt after captive portal login |
| 278 | // succeeds. |
| 279 | tracker[server] = (reevaluationStatus == NEEDS_REEVALUATION) ? Validation::in_process |
| 280 | : Validation::fail; |
chenbruce | aff8584 | 2019-05-31 15:46:42 +0800 | [diff] [blame^] | 281 | LOG(VERBOSE) << "Validation failed for " << addrToString(&server.ss) << "!"; |
Mike Yu | b601ff7 | 2018-11-01 20:07:00 +0800 | [diff] [blame] | 282 | } |
| 283 | |
| 284 | return reevaluationStatus; |
| 285 | } |
| 286 | |
| 287 | // Start validation for newly added servers as well as any servers that have |
| 288 | // landed in Validation::fail state. Note that servers that have failed |
| 289 | // multiple validation attempts but for which there is still a validating |
| 290 | // thread running are marked as being Validation::in_process. |
| 291 | bool PrivateDnsConfiguration::needsValidation(const PrivateDnsTracker& tracker, |
| 292 | const DnsTlsServer& server) { |
| 293 | const auto& iter = tracker.find(server); |
| 294 | return (iter == tracker.end()) || (iter->second == Validation::fail); |
| 295 | } |
| 296 | |
| 297 | PrivateDnsConfiguration gPrivateDnsConfiguration; |
| 298 | |
| 299 | } // namespace net |
| 300 | } // namespace android |