| /* |
| * Copyright (C) 2011 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #define LOG_TAG "ResolverController" |
| #define DBG 0 |
| |
| #include <algorithm> |
| #include <cstdlib> |
| #include <map> |
| #include <mutex> |
| #include <set> |
| #include <string> |
| #include <thread> |
| #include <utility> |
| #include <vector> |
| #include <cutils/log.h> |
| #include <net/if.h> |
| #include <sys/socket.h> |
| #include <netdb.h> |
| |
| #include <arpa/inet.h> |
| // NOTE: <resolv_netid.h> is a private C library header that provides |
| // declarations for _resolv_set_nameservers_for_net and |
| // _resolv_flush_cache_for_net |
| #include <resolv_netid.h> |
| #include <resolv_params.h> |
| #include <resolv_stats.h> |
| |
| #include <android-base/strings.h> |
| #include <android/net/INetd.h> |
| |
| #include "DumpWriter.h" |
| #include "NetdConstants.h" |
| #include "ResolverController.h" |
| #include "ResolverStats.h" |
| #include "dns/DnsTlsTransport.h" |
| |
| namespace android { |
| namespace net { |
| |
| namespace { |
| |
| struct PrivateDnsServer { |
| PrivateDnsServer(const sockaddr_storage& ss) : ss(ss) {} |
| const sockaddr_storage ss; |
| // For now, the fingerprints are always SHA-256. This is the only digest algorithm |
| // that is mandatory to support (https://tools.ietf.org/html/rfc7858#section-4.2). |
| std::set<std::vector<uint8_t>> fingerprints; |
| }; |
| |
| // This comparison ignores ports and fingerprints. |
| bool operator<(const PrivateDnsServer& x, const PrivateDnsServer& y) { |
| if (x.ss.ss_family != y.ss.ss_family) { |
| return x.ss.ss_family < y.ss.ss_family; |
| } |
| // Same address family. Compare IP addresses. |
| if (x.ss.ss_family == AF_INET) { |
| const sockaddr_in& x_sin = reinterpret_cast<const sockaddr_in&>(x.ss); |
| const sockaddr_in& y_sin = reinterpret_cast<const sockaddr_in&>(y.ss); |
| return x_sin.sin_addr.s_addr < y_sin.sin_addr.s_addr; |
| } else if (x.ss.ss_family == AF_INET6) { |
| const sockaddr_in6& x_sin6 = reinterpret_cast<const sockaddr_in6&>(x.ss); |
| const sockaddr_in6& y_sin6 = reinterpret_cast<const sockaddr_in6&>(y.ss); |
| return std::memcmp(x_sin6.sin6_addr.s6_addr, y_sin6.sin6_addr.s6_addr, 16) < 0; |
| } |
| return false; // Unknown address type. This is an error. |
| } |
| |
| bool parseServer(const char* server, in_port_t port, sockaddr_storage* parsed) { |
| sockaddr_in* sin = reinterpret_cast<sockaddr_in*>(parsed); |
| if (inet_pton(AF_INET, server, &(sin->sin_addr)) == 1) { |
| // IPv4 parse succeeded, so it's IPv4 |
| sin->sin_family = AF_INET; |
| sin->sin_port = htons(port); |
| return true; |
| } |
| sockaddr_in6* sin6 = reinterpret_cast<sockaddr_in6*>(parsed); |
| if (inet_pton(AF_INET6, server, &(sin6->sin6_addr)) == 1){ |
| // IPv6 parse succeeded, so it's IPv6. |
| sin6->sin6_family = AF_INET6; |
| sin6->sin6_port = htons(port); |
| return true; |
| } |
| if (DBG) { |
| ALOGW("Failed to parse server address: %s", server); |
| } |
| return false; |
| } |
| |
| // Structure for tracking the entire set of known Private DNS servers. |
| std::mutex privateDnsLock; |
| typedef std::set<PrivateDnsServer> PrivateDnsSet; |
| PrivateDnsSet privateDnsServers; |
| |
| // Structure for tracking the validation status of servers on a specific netid. |
| // Servers that fail validation are removed from the tracker, and can be retried. |
| enum class Validation : bool { in_process, success }; |
| typedef std::map<PrivateDnsServer, Validation> PrivateDnsTracker; |
| std::map<unsigned, PrivateDnsTracker> privateDnsTransports; |
| |
| PrivateDnsSet parseServers(const char** servers, int numservers, in_port_t port) { |
| PrivateDnsSet set; |
| for (int i = 0; i < numservers; ++i) { |
| sockaddr_storage parsed; |
| if (parseServer(servers[i], port, &parsed)) { |
| set.insert(parsed); |
| } |
| } |
| return set; |
| } |
| |
| void checkPrivateDnsProviders(const unsigned netId, const char** servers, int numservers) { |
| if (DBG) { |
| ALOGD("checkPrivateDnsProviders(%u)", netId); |
| } |
| |
| std::lock_guard<std::mutex> guard(privateDnsLock); |
| if (privateDnsServers.empty()) { |
| return; |
| } |
| |
| // First compute the intersection of the servers to check with the |
| // servers that are permitted to use DNS over TLS. The intersection |
| // will contain the port number to be used for Private DNS. |
| PrivateDnsSet serversToCheck = parseServers(servers, numservers, 53); |
| PrivateDnsSet intersection; |
| std::set_intersection(privateDnsServers.begin(), privateDnsServers.end(), |
| serversToCheck.begin(), serversToCheck.end(), |
| std::inserter(intersection, intersection.begin())); |
| if (intersection.empty()) { |
| return; |
| } |
| |
| auto netPair = privateDnsTransports.find(netId); |
| if (netPair == privateDnsTransports.end()) { |
| // New netId |
| bool added; |
| std::tie(netPair, added) = privateDnsTransports.emplace(netId, PrivateDnsTracker()); |
| if (!added) { |
| ALOGE("Memory error while checking private DNS for netId %d", netId); |
| return; |
| } |
| } |
| |
| auto& tracker = netPair->second; |
| for (const auto& privateServer : intersection) { |
| if (tracker.count(privateServer) != 0) { |
| continue; |
| } |
| tracker[privateServer] = Validation::in_process; |
| std::thread validate_thread([privateServer, netId] { |
| // validateDnsTlsServer() is a blocking call that performs network operations. |
| // It can take milliseconds to minutes, up to the SYN retry limit. |
| bool success = validateDnsTlsServer(netId, |
| privateServer.ss, privateServer.fingerprints); |
| std::lock_guard<std::mutex> guard(privateDnsLock); |
| auto netPair = privateDnsTransports.find(netId); |
| if (netPair == privateDnsTransports.end()) { |
| ALOGW("netId %u was erased during private DNS validation", netId); |
| return; |
| } |
| auto& tracker = netPair->second; |
| if (privateDnsServers.count(privateServer) == 0) { |
| ALOGW("Server was removed during private DNS validation"); |
| success = false; |
| } |
| if (success) { |
| tracker[privateServer] = Validation::success; |
| } else { |
| // Validation failure is expected if a user is on a captive portal. |
| // TODO: Trigger a second validation attempt after captive portal login |
| // succeeds. |
| tracker.erase(privateServer); |
| } |
| }); |
| validate_thread.detach(); |
| } |
| } |
| |
| void clearPrivateDnsProviders(unsigned netId) { |
| if (DBG) { |
| ALOGD("clearPrivateDnsProviders(%u)", netId); |
| } |
| std::lock_guard<std::mutex> guard(privateDnsLock); |
| privateDnsTransports.erase(netId); |
| } |
| |
| } // namespace |
| |
| int ResolverController::setDnsServers(unsigned netId, const char* searchDomains, |
| const char** servers, int numservers, const __res_params* params) { |
| if (DBG) { |
| ALOGD("setDnsServers netId = %u\n", netId); |
| } |
| checkPrivateDnsProviders(netId, servers, numservers); |
| return -_resolv_set_nameservers_for_net(netId, servers, numservers, searchDomains, params); |
| } |
| |
| bool ResolverController::shouldUseTls(unsigned netId, const sockaddr_storage& insecureServer, |
| sockaddr_storage* secureServer, std::set<std::vector<uint8_t>>* fingerprints) { |
| // This mutex is on the critical path of every DNS lookup that doesn't hit a local cache. |
| // If the overhead of mutex acquisition proves too high, we could reduce it by maintaining |
| // an atomic_int32_t counter of validated connections, and returning early if it's zero. |
| std::lock_guard<std::mutex> guard(privateDnsLock); |
| const auto netPair = privateDnsTransports.find(netId); |
| if (netPair == privateDnsTransports.end()) { |
| return false; |
| } |
| const auto& tracker = netPair->second; |
| const auto serverPair = tracker.find(insecureServer); |
| if (serverPair == tracker.end() || serverPair->second != Validation::success) { |
| return false; |
| } |
| const auto& validatedServer = serverPair->first; |
| *secureServer = validatedServer.ss; |
| *fingerprints = validatedServer.fingerprints; |
| return true; |
| } |
| |
| int ResolverController::clearDnsServers(unsigned netId) { |
| _resolv_set_nameservers_for_net(netId, NULL, 0, "", NULL); |
| if (DBG) { |
| ALOGD("clearDnsServers netId = %u\n", netId); |
| } |
| clearPrivateDnsProviders(netId); |
| return 0; |
| } |
| |
| int ResolverController::flushDnsCache(unsigned netId) { |
| if (DBG) { |
| ALOGD("flushDnsCache netId = %u\n", netId); |
| } |
| |
| _resolv_flush_cache_for_net(netId); |
| |
| return 0; |
| } |
| |
| int ResolverController::getDnsInfo(unsigned netId, std::vector<std::string>* servers, |
| std::vector<std::string>* domains, __res_params* params, |
| std::vector<android::net::ResolverStats>* stats) { |
| using android::net::ResolverStats; |
| using android::net::INetd; |
| static_assert(ResolverStats::STATS_SUCCESSES == INetd::RESOLVER_STATS_SUCCESSES && |
| ResolverStats::STATS_ERRORS == INetd::RESOLVER_STATS_ERRORS && |
| ResolverStats::STATS_TIMEOUTS == INetd::RESOLVER_STATS_TIMEOUTS && |
| ResolverStats::STATS_INTERNAL_ERRORS == INetd::RESOLVER_STATS_INTERNAL_ERRORS && |
| ResolverStats::STATS_RTT_AVG == INetd::RESOLVER_STATS_RTT_AVG && |
| ResolverStats::STATS_LAST_SAMPLE_TIME == INetd::RESOLVER_STATS_LAST_SAMPLE_TIME && |
| ResolverStats::STATS_USABLE == INetd::RESOLVER_STATS_USABLE && |
| ResolverStats::STATS_COUNT == INetd::RESOLVER_STATS_COUNT, |
| "AIDL and ResolverStats.h out of sync"); |
| int nscount = -1; |
| sockaddr_storage res_servers[MAXNS]; |
| int dcount = -1; |
| char res_domains[MAXDNSRCH][MAXDNSRCHPATH]; |
| __res_stats res_stats[MAXNS]; |
| servers->clear(); |
| domains->clear(); |
| *params = __res_params{}; |
| stats->clear(); |
| int revision_id = android_net_res_stats_get_info_for_net(netId, &nscount, res_servers, &dcount, |
| res_domains, params, res_stats); |
| |
| // If the netId is unknown (which can happen for valid net IDs for which no DNS servers have |
| // yet been configured), there is no revision ID. In this case there is no data to return. |
| if (revision_id < 0) { |
| return 0; |
| } |
| |
| // Verify that the returned data is sane. |
| if (nscount < 0 || nscount > MAXNS || dcount < 0 || dcount > MAXDNSRCH) { |
| ALOGE("%s: nscount=%d, dcount=%d", __FUNCTION__, nscount, dcount); |
| return -ENOTRECOVERABLE; |
| } |
| |
| // Determine which servers are considered usable by the resolver. |
| bool valid_servers[MAXNS]; |
| std::fill_n(valid_servers, MAXNS, false); |
| android_net_res_stats_get_usable_servers(params, res_stats, nscount, valid_servers); |
| |
| // Convert the server sockaddr structures to std::string. |
| stats->resize(nscount); |
| for (int i = 0 ; i < nscount ; ++i) { |
| char hbuf[NI_MAXHOST]; |
| int rv = getnameinfo(reinterpret_cast<const sockaddr*>(&res_servers[i]), |
| sizeof(res_servers[i]), hbuf, sizeof(hbuf), nullptr, 0, NI_NUMERICHOST); |
| std::string server_str; |
| if (rv == 0) { |
| server_str.assign(hbuf); |
| } else { |
| ALOGE("getnameinfo() failed for server #%d: %s", i, gai_strerror(rv)); |
| server_str.assign("<invalid>"); |
| } |
| servers->push_back(std::move(server_str)); |
| android::net::ResolverStats& cur_stats = (*stats)[i]; |
| android_net_res_stats_aggregate(&res_stats[i], &cur_stats.successes, &cur_stats.errors, |
| &cur_stats.timeouts, &cur_stats.internal_errors, &cur_stats.rtt_avg, |
| &cur_stats.last_sample_time); |
| cur_stats.usable = valid_servers[i]; |
| } |
| |
| // Convert the stack-allocated search domain strings to std::string. |
| for (int i = 0 ; i < dcount ; ++i) { |
| domains->push_back(res_domains[i]); |
| } |
| return 0; |
| } |
| |
| int ResolverController::setResolverConfiguration(int32_t netId, |
| const std::vector<std::string>& servers, const std::vector<std::string>& domains, |
| const std::vector<int32_t>& params) { |
| using android::net::INetd; |
| if (params.size() != INetd::RESOLVER_PARAMS_COUNT) { |
| ALOGE("%s: params.size()=%zu", __FUNCTION__, params.size()); |
| return -EINVAL; |
| } |
| |
| auto server_count = std::min<size_t>(MAXNS, servers.size()); |
| std::vector<const char*> server_ptrs; |
| for (size_t i = 0 ; i < server_count ; ++i) { |
| server_ptrs.push_back(servers[i].c_str()); |
| } |
| |
| std::string domains_str; |
| if (!domains.empty()) { |
| domains_str = domains[0]; |
| for (size_t i = 1 ; i < domains.size() ; ++i) { |
| domains_str += " " + domains[i]; |
| } |
| } |
| |
| __res_params res_params; |
| res_params.sample_validity = params[INetd::RESOLVER_PARAMS_SAMPLE_VALIDITY]; |
| res_params.success_threshold = params[INetd::RESOLVER_PARAMS_SUCCESS_THRESHOLD]; |
| res_params.min_samples = params[INetd::RESOLVER_PARAMS_MIN_SAMPLES]; |
| res_params.max_samples = params[INetd::RESOLVER_PARAMS_MAX_SAMPLES]; |
| |
| return setDnsServers(netId, domains_str.c_str(), server_ptrs.data(), server_ptrs.size(), |
| &res_params); |
| } |
| |
| int ResolverController::getResolverInfo(int32_t netId, std::vector<std::string>* servers, |
| std::vector<std::string>* domains, std::vector<int32_t>* params, |
| std::vector<int32_t>* stats) { |
| using android::net::ResolverStats; |
| using android::net::INetd; |
| __res_params res_params; |
| std::vector<ResolverStats> res_stats; |
| int ret = getDnsInfo(netId, servers, domains, &res_params, &res_stats); |
| if (ret != 0) { |
| return ret; |
| } |
| |
| // Serialize the information for binder. |
| ResolverStats::encodeAll(res_stats, stats); |
| |
| params->resize(INetd::RESOLVER_PARAMS_COUNT); |
| (*params)[INetd::RESOLVER_PARAMS_SAMPLE_VALIDITY] = res_params.sample_validity; |
| (*params)[INetd::RESOLVER_PARAMS_SUCCESS_THRESHOLD] = res_params.success_threshold; |
| (*params)[INetd::RESOLVER_PARAMS_MIN_SAMPLES] = res_params.min_samples; |
| (*params)[INetd::RESOLVER_PARAMS_MAX_SAMPLES] = res_params.max_samples; |
| return 0; |
| } |
| |
| void ResolverController::dump(DumpWriter& dw, unsigned netId) { |
| // No lock needed since Bionic's resolver locks all accessed data structures internally. |
| using android::net::ResolverStats; |
| std::vector<std::string> servers; |
| std::vector<std::string> domains; |
| __res_params params; |
| std::vector<ResolverStats> stats; |
| time_t now = time(nullptr); |
| int rv = getDnsInfo(netId, &servers, &domains, ¶ms, &stats); |
| dw.incIndent(); |
| if (rv != 0) { |
| dw.println("getDnsInfo() failed for netid %u", netId); |
| } else { |
| if (servers.empty()) { |
| dw.println("No DNS servers defined"); |
| } else { |
| dw.println("DNS servers: # IP (total, successes, errors, timeouts, internal errors, " |
| "RTT avg, last sample)"); |
| dw.incIndent(); |
| for (size_t i = 0 ; i < servers.size() ; ++i) { |
| if (i < stats.size()) { |
| const ResolverStats& s = stats[i]; |
| int total = s.successes + s.errors + s.timeouts + s.internal_errors; |
| if (total > 0) { |
| int time_delta = (s.last_sample_time > 0) ? now - s.last_sample_time : -1; |
| dw.println("%s (%d, %d, %d, %d, %d, %dms, %ds)%s", servers[i].c_str(), |
| total, s.successes, s.errors, s.timeouts, s.internal_errors, |
| s.rtt_avg, time_delta, s.usable ? "" : " BROKEN"); |
| } else { |
| dw.println("%s <no data>", servers[i].c_str()); |
| } |
| } else { |
| dw.println("%s <no stats>", servers[i].c_str()); |
| } |
| } |
| dw.decIndent(); |
| } |
| if (domains.empty()) { |
| dw.println("No search domains defined"); |
| } else { |
| std::string domains_str = android::base::Join(domains, ", "); |
| dw.println("search domains: %s", domains_str.c_str()); |
| } |
| if (params.sample_validity != 0) { |
| dw.println("DNS parameters: sample validity = %us, success threshold = %u%%, " |
| "samples (min, max) = (%u, %u)", params.sample_validity, |
| static_cast<unsigned>(params.success_threshold), |
| static_cast<unsigned>(params.min_samples), |
| static_cast<unsigned>(params.max_samples)); |
| } |
| } |
| dw.decIndent(); |
| } |
| |
| int ResolverController::addPrivateDnsServer(const std::string& server, int32_t port, |
| const std::string& fingerprintAlgorithm, |
| const std::set<std::vector<uint8_t>>& fingerprints) { |
| using android::net::INetd; |
| if (fingerprintAlgorithm.empty()) { |
| if (!fingerprints.empty()) { |
| return INetd::PRIVATE_DNS_BAD_FINGERPRINT; |
| } |
| } else if (fingerprintAlgorithm.compare("SHA-256") == 0) { |
| if (fingerprints.empty()) { |
| return INetd::PRIVATE_DNS_BAD_FINGERPRINT; |
| } |
| for (const auto& fingerprint : fingerprints) { |
| if (fingerprint.size() != SHA256_SIZE) { |
| return INetd::PRIVATE_DNS_BAD_FINGERPRINT; |
| } |
| } |
| } else { |
| return INetd::PRIVATE_DNS_UNKNOWN_ALGORITHM; |
| } |
| if (port <= 0 || port > 0xFFFF) { |
| return INetd::PRIVATE_DNS_BAD_PORT; |
| } |
| sockaddr_storage parsed; |
| if (!parseServer(server.c_str(), port, &parsed)) { |
| return INetd::PRIVATE_DNS_BAD_ADDRESS; |
| } |
| PrivateDnsServer privateServer(parsed); |
| privateServer.fingerprints = fingerprints; |
| std::lock_guard<std::mutex> guard(privateDnsLock); |
| // Ensure we overwrite any previous matching server. This is necessary because equality is |
| // based only on the IP address, not the port or fingerprints. |
| privateDnsServers.erase(privateServer); |
| privateDnsServers.insert(privateServer); |
| return INetd::PRIVATE_DNS_SUCCESS; |
| } |
| |
| int ResolverController::removePrivateDnsServer(const std::string& server) { |
| using android::net::INetd; |
| sockaddr_storage parsed; |
| if (!parseServer(server.c_str(), 0, &parsed)) { |
| return INetd::PRIVATE_DNS_BAD_ADDRESS; |
| } |
| std::lock_guard<std::mutex> guard(privateDnsLock); |
| privateDnsServers.erase(parsed); |
| for (auto& pair : privateDnsTransports) { |
| pair.second.erase(parsed); |
| } |
| return INetd::PRIVATE_DNS_SUCCESS; |
| } |
| |
| } // namespace net |
| } // namespace android |
