| /* |
| * Copyright (C) 2018 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. |
| */ |
| |
| package com.android.server.connectivity; |
| |
| import static android.net.ConnectivityManager.PRIVATE_DNS_DEFAULT_MODE_FALLBACK; |
| import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OFF; |
| import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_PROVIDER_HOSTNAME; |
| import static android.provider.Settings.Global.DNS_RESOLVER_MAX_SAMPLES; |
| import static android.provider.Settings.Global.DNS_RESOLVER_MIN_SAMPLES; |
| import static android.provider.Settings.Global.DNS_RESOLVER_SAMPLE_VALIDITY_SECONDS; |
| import static android.provider.Settings.Global.DNS_RESOLVER_SUCCESS_THRESHOLD_PERCENT; |
| import static android.provider.Settings.Global.PRIVATE_DNS_DEFAULT_MODE; |
| import static android.provider.Settings.Global.PRIVATE_DNS_MODE; |
| import static android.provider.Settings.Global.PRIVATE_DNS_SPECIFIER; |
| |
| import android.content.ContentResolver; |
| import android.content.Context; |
| import android.content.Intent; |
| import android.net.LinkProperties; |
| import android.net.Network; |
| import android.net.NetworkUtils; |
| import android.net.Uri; |
| import android.net.shared.PrivateDnsConfig; |
| import android.os.Binder; |
| import android.os.INetworkManagementService; |
| import android.os.UserHandle; |
| import android.provider.Settings; |
| import android.text.TextUtils; |
| import android.util.Pair; |
| import android.util.Slog; |
| |
| import java.net.InetAddress; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.stream.Collectors; |
| |
| |
| /** |
| * Encapsulate the management of DNS settings for networks. |
| * |
| * This class it NOT designed for concurrent access. Furthermore, all non-static |
| * methods MUST be called from ConnectivityService's thread. |
| * |
| * [ Private DNS ] |
| * The code handling Private DNS is spread across several components, but this |
| * seems like the least bad place to collect all the observations. |
| * |
| * Private DNS handling and updating occurs in response to several different |
| * events. Each is described here with its corresponding intended handling. |
| * |
| * [A] Event: A new network comes up. |
| * Mechanics: |
| * [1] ConnectivityService gets notifications from NetworkAgents. |
| * [2] in updateNetworkInfo(), the first time the NetworkAgent goes into |
| * into CONNECTED state, the Private DNS configuration is retrieved, |
| * programmed, and strict mode hostname resolution (if applicable) is |
| * enqueued in NetworkAgent's NetworkMonitor, via a call to |
| * handlePerNetworkPrivateDnsConfig(). |
| * [3] Re-resolution of strict mode hostnames that fail to return any |
| * IP addresses happens inside NetworkMonitor; it sends itself a |
| * delayed CMD_EVALUATE_PRIVATE_DNS message in a simple backoff |
| * schedule. |
| * [4] Successfully resolved hostnames are sent to ConnectivityService |
| * inside an EVENT_PRIVATE_DNS_CONFIG_RESOLVED message. The resolved |
| * IP addresses are programmed into netd via: |
| * |
| * updatePrivateDns() -> updateDnses() |
| * |
| * both of which make calls into DnsManager. |
| * [5] Upon a successful hostname resolution NetworkMonitor initiates a |
| * validation attempt in the form of a lookup for a one-time hostname |
| * that uses Private DNS. |
| * |
| * [B] Event: Private DNS settings are changed. |
| * Mechanics: |
| * [1] ConnectivityService gets notifications from its SettingsObserver. |
| * [2] handlePrivateDnsSettingsChanged() is called, which calls |
| * handlePerNetworkPrivateDnsConfig() and the process proceeds |
| * as if from A.3 above. |
| * |
| * [C] Event: An application calls ConnectivityManager#reportBadNetwork(). |
| * Mechanics: |
| * [1] NetworkMonitor is notified and initiates a reevaluation, which |
| * always bypasses Private DNS. |
| * [2] Once completed, NetworkMonitor checks if strict mode is in operation |
| * and if so enqueues another evaluation of Private DNS, as if from |
| * step A.5 above. |
| * |
| * @hide |
| */ |
| public class DnsManager { |
| private static final String TAG = DnsManager.class.getSimpleName(); |
| private static final PrivateDnsConfig PRIVATE_DNS_OFF = new PrivateDnsConfig(); |
| |
| /* Defaults for resolver parameters. */ |
| private static final int DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS = 1800; |
| private static final int DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT = 25; |
| private static final int DNS_RESOLVER_DEFAULT_MIN_SAMPLES = 8; |
| private static final int DNS_RESOLVER_DEFAULT_MAX_SAMPLES = 64; |
| |
| public static PrivateDnsConfig getPrivateDnsConfig(ContentResolver cr) { |
| final String mode = getPrivateDnsMode(cr); |
| |
| final boolean useTls = !TextUtils.isEmpty(mode) && !PRIVATE_DNS_MODE_OFF.equals(mode); |
| |
| if (PRIVATE_DNS_MODE_PROVIDER_HOSTNAME.equals(mode)) { |
| final String specifier = getStringSetting(cr, PRIVATE_DNS_SPECIFIER); |
| return new PrivateDnsConfig(specifier, null); |
| } |
| |
| return new PrivateDnsConfig(useTls); |
| } |
| |
| public static Uri[] getPrivateDnsSettingsUris() { |
| return new Uri[]{ |
| Settings.Global.getUriFor(PRIVATE_DNS_DEFAULT_MODE), |
| Settings.Global.getUriFor(PRIVATE_DNS_MODE), |
| Settings.Global.getUriFor(PRIVATE_DNS_SPECIFIER), |
| }; |
| } |
| |
| public static class PrivateDnsValidationUpdate { |
| final public int netId; |
| final public InetAddress ipAddress; |
| final public String hostname; |
| final public boolean validated; |
| |
| public PrivateDnsValidationUpdate(int netId, InetAddress ipAddress, |
| String hostname, boolean validated) { |
| this.netId = netId; |
| this.ipAddress = ipAddress; |
| this.hostname = hostname; |
| this.validated = validated; |
| } |
| } |
| |
| private static class PrivateDnsValidationStatuses { |
| enum ValidationStatus { |
| IN_PROGRESS, |
| FAILED, |
| SUCCEEDED |
| } |
| |
| // Validation statuses of <hostname, ipAddress> pairs for a single netId |
| // Caution : not thread-safe. As mentioned in the top file comment, all |
| // methods of this class must only be called on ConnectivityService's thread. |
| private Map<Pair<String, InetAddress>, ValidationStatus> mValidationMap; |
| |
| private PrivateDnsValidationStatuses() { |
| mValidationMap = new HashMap<>(); |
| } |
| |
| private boolean hasValidatedServer() { |
| for (ValidationStatus status : mValidationMap.values()) { |
| if (status == ValidationStatus.SUCCEEDED) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private void updateTrackedDnses(String[] ipAddresses, String hostname) { |
| Set<Pair<String, InetAddress>> latestDnses = new HashSet<>(); |
| for (String ipAddress : ipAddresses) { |
| try { |
| latestDnses.add(new Pair(hostname, |
| InetAddress.parseNumericAddress(ipAddress))); |
| } catch (IllegalArgumentException e) {} |
| } |
| // Remove <hostname, ipAddress> pairs that should not be tracked. |
| for (Iterator<Map.Entry<Pair<String, InetAddress>, ValidationStatus>> it = |
| mValidationMap.entrySet().iterator(); it.hasNext(); ) { |
| Map.Entry<Pair<String, InetAddress>, ValidationStatus> entry = it.next(); |
| if (!latestDnses.contains(entry.getKey())) { |
| it.remove(); |
| } |
| } |
| // Add new <hostname, ipAddress> pairs that should be tracked. |
| for (Pair<String, InetAddress> p : latestDnses) { |
| if (!mValidationMap.containsKey(p)) { |
| mValidationMap.put(p, ValidationStatus.IN_PROGRESS); |
| } |
| } |
| } |
| |
| private void updateStatus(PrivateDnsValidationUpdate update) { |
| Pair<String, InetAddress> p = new Pair(update.hostname, |
| update.ipAddress); |
| if (!mValidationMap.containsKey(p)) { |
| return; |
| } |
| if (update.validated) { |
| mValidationMap.put(p, ValidationStatus.SUCCEEDED); |
| } else { |
| mValidationMap.put(p, ValidationStatus.FAILED); |
| } |
| } |
| |
| private LinkProperties fillInValidatedPrivateDns(LinkProperties lp) { |
| lp.setValidatedPrivateDnsServers(Collections.EMPTY_LIST); |
| mValidationMap.forEach((key, value) -> { |
| if (value == ValidationStatus.SUCCEEDED) { |
| lp.addValidatedPrivateDnsServer(key.second); |
| } |
| }); |
| return lp; |
| } |
| } |
| |
| private final Context mContext; |
| private final ContentResolver mContentResolver; |
| private final INetworkManagementService mNMS; |
| private final MockableSystemProperties mSystemProperties; |
| // TODO: Replace these Maps with SparseArrays. |
| private final Map<Integer, PrivateDnsConfig> mPrivateDnsMap; |
| private final Map<Integer, PrivateDnsValidationStatuses> mPrivateDnsValidationMap; |
| |
| private int mNumDnsEntries; |
| private int mSampleValidity; |
| private int mSuccessThreshold; |
| private int mMinSamples; |
| private int mMaxSamples; |
| private String mPrivateDnsMode; |
| private String mPrivateDnsSpecifier; |
| |
| public DnsManager(Context ctx, INetworkManagementService nms, MockableSystemProperties sp) { |
| mContext = ctx; |
| mContentResolver = mContext.getContentResolver(); |
| mNMS = nms; |
| mSystemProperties = sp; |
| mPrivateDnsMap = new HashMap<>(); |
| mPrivateDnsValidationMap = new HashMap<>(); |
| |
| // TODO: Create and register ContentObservers to track every setting |
| // used herein, posting messages to respond to changes. |
| } |
| |
| public PrivateDnsConfig getPrivateDnsConfig() { |
| return getPrivateDnsConfig(mContentResolver); |
| } |
| |
| public void removeNetwork(Network network) { |
| mPrivateDnsMap.remove(network.netId); |
| mPrivateDnsValidationMap.remove(network.netId); |
| } |
| |
| public PrivateDnsConfig updatePrivateDns(Network network, PrivateDnsConfig cfg) { |
| Slog.w(TAG, "updatePrivateDns(" + network + ", " + cfg + ")"); |
| return (cfg != null) |
| ? mPrivateDnsMap.put(network.netId, cfg) |
| : mPrivateDnsMap.remove(network.netId); |
| } |
| |
| public void updatePrivateDnsStatus(int netId, LinkProperties lp) { |
| // Use the PrivateDnsConfig data pushed to this class instance |
| // from ConnectivityService. |
| final PrivateDnsConfig privateDnsCfg = mPrivateDnsMap.getOrDefault(netId, |
| PRIVATE_DNS_OFF); |
| |
| final boolean useTls = privateDnsCfg.useTls; |
| final PrivateDnsValidationStatuses statuses = |
| useTls ? mPrivateDnsValidationMap.get(netId) : null; |
| final boolean validated = (null != statuses) && statuses.hasValidatedServer(); |
| final boolean strictMode = privateDnsCfg.inStrictMode(); |
| final String tlsHostname = strictMode ? privateDnsCfg.hostname : null; |
| final boolean usingPrivateDns = strictMode || validated; |
| |
| lp.setUsePrivateDns(usingPrivateDns); |
| lp.setPrivateDnsServerName(tlsHostname); |
| if (usingPrivateDns && null != statuses) { |
| statuses.fillInValidatedPrivateDns(lp); |
| } else { |
| lp.setValidatedPrivateDnsServers(Collections.EMPTY_LIST); |
| } |
| } |
| |
| public void updatePrivateDnsValidation(PrivateDnsValidationUpdate update) { |
| final PrivateDnsValidationStatuses statuses = |
| mPrivateDnsValidationMap.get(update.netId); |
| if (statuses == null) return; |
| statuses.updateStatus(update); |
| } |
| |
| public void setDnsConfigurationForNetwork( |
| int netId, LinkProperties lp, boolean isDefaultNetwork) { |
| final String[] assignedServers = NetworkUtils.makeStrings(lp.getDnsServers()); |
| final String[] domainStrs = getDomainStrings(lp.getDomains()); |
| |
| updateParametersSettings(); |
| final int[] params = { mSampleValidity, mSuccessThreshold, mMinSamples, mMaxSamples }; |
| |
| // We only use the PrivateDnsConfig data pushed to this class instance |
| // from ConnectivityService because it works in coordination with |
| // NetworkMonitor to decide which networks need validation and runs the |
| // blocking calls to resolve Private DNS strict mode hostnames. |
| // |
| // At this time we do not attempt to enable Private DNS on non-Internet |
| // networks like IMS. |
| final PrivateDnsConfig privateDnsCfg = mPrivateDnsMap.getOrDefault(netId, |
| PRIVATE_DNS_OFF); |
| |
| final boolean useTls = privateDnsCfg.useTls; |
| final boolean strictMode = privateDnsCfg.inStrictMode(); |
| final String tlsHostname = strictMode ? privateDnsCfg.hostname : ""; |
| final String[] tlsServers = |
| strictMode ? NetworkUtils.makeStrings( |
| Arrays.stream(privateDnsCfg.ips) |
| .filter((ip) -> lp.isReachable(ip)) |
| .collect(Collectors.toList())) |
| : useTls ? assignedServers // Opportunistic |
| : new String[0]; // Off |
| |
| // Prepare to track the validation status of the DNS servers in the |
| // resolver config when private DNS is in opportunistic or strict mode. |
| if (useTls) { |
| if (!mPrivateDnsValidationMap.containsKey(netId)) { |
| mPrivateDnsValidationMap.put(netId, new PrivateDnsValidationStatuses()); |
| } |
| mPrivateDnsValidationMap.get(netId).updateTrackedDnses(tlsServers, tlsHostname); |
| } else { |
| mPrivateDnsValidationMap.remove(netId); |
| } |
| |
| Slog.d(TAG, String.format("setDnsConfigurationForNetwork(%d, %s, %s, %s, %s, %s)", |
| netId, Arrays.toString(assignedServers), Arrays.toString(domainStrs), |
| Arrays.toString(params), tlsHostname, Arrays.toString(tlsServers))); |
| try { |
| mNMS.setDnsConfigurationForNetwork( |
| netId, assignedServers, domainStrs, params, tlsHostname, tlsServers); |
| } catch (Exception e) { |
| Slog.e(TAG, "Error setting DNS configuration: " + e); |
| return; |
| } |
| |
| // TODO: netd should listen on [::1]:53 and proxy queries to the current |
| // default network, and we should just set net.dns1 to ::1, not least |
| // because applications attempting to use net.dns resolvers will bypass |
| // the privacy protections of things like DNS-over-TLS. |
| if (isDefaultNetwork) setDefaultDnsSystemProperties(lp.getDnsServers()); |
| flushVmDnsCache(); |
| } |
| |
| public void setDefaultDnsSystemProperties(Collection<InetAddress> dnses) { |
| int last = 0; |
| for (InetAddress dns : dnses) { |
| ++last; |
| setNetDnsProperty(last, dns.getHostAddress()); |
| } |
| for (int i = last + 1; i <= mNumDnsEntries; ++i) { |
| setNetDnsProperty(i, ""); |
| } |
| mNumDnsEntries = last; |
| } |
| |
| private void flushVmDnsCache() { |
| /* |
| * Tell the VMs to toss their DNS caches |
| */ |
| final Intent intent = new Intent(Intent.ACTION_CLEAR_DNS_CACHE); |
| intent.addFlags(Intent.FLAG_RECEIVER_REPLACE_PENDING); |
| /* |
| * Connectivity events can happen before boot has completed ... |
| */ |
| intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT); |
| final long ident = Binder.clearCallingIdentity(); |
| try { |
| mContext.sendBroadcastAsUser(intent, UserHandle.ALL); |
| } finally { |
| Binder.restoreCallingIdentity(ident); |
| } |
| } |
| |
| private void updateParametersSettings() { |
| mSampleValidity = getIntSetting( |
| DNS_RESOLVER_SAMPLE_VALIDITY_SECONDS, |
| DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS); |
| if (mSampleValidity < 0 || mSampleValidity > 65535) { |
| Slog.w(TAG, "Invalid sampleValidity=" + mSampleValidity + ", using default=" + |
| DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS); |
| mSampleValidity = DNS_RESOLVER_DEFAULT_SAMPLE_VALIDITY_SECONDS; |
| } |
| |
| mSuccessThreshold = getIntSetting( |
| DNS_RESOLVER_SUCCESS_THRESHOLD_PERCENT, |
| DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT); |
| if (mSuccessThreshold < 0 || mSuccessThreshold > 100) { |
| Slog.w(TAG, "Invalid successThreshold=" + mSuccessThreshold + ", using default=" + |
| DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT); |
| mSuccessThreshold = DNS_RESOLVER_DEFAULT_SUCCESS_THRESHOLD_PERCENT; |
| } |
| |
| mMinSamples = getIntSetting(DNS_RESOLVER_MIN_SAMPLES, DNS_RESOLVER_DEFAULT_MIN_SAMPLES); |
| mMaxSamples = getIntSetting(DNS_RESOLVER_MAX_SAMPLES, DNS_RESOLVER_DEFAULT_MAX_SAMPLES); |
| if (mMinSamples < 0 || mMinSamples > mMaxSamples || mMaxSamples > 64) { |
| Slog.w(TAG, "Invalid sample count (min, max)=(" + mMinSamples + ", " + mMaxSamples + |
| "), using default=(" + DNS_RESOLVER_DEFAULT_MIN_SAMPLES + ", " + |
| DNS_RESOLVER_DEFAULT_MAX_SAMPLES + ")"); |
| mMinSamples = DNS_RESOLVER_DEFAULT_MIN_SAMPLES; |
| mMaxSamples = DNS_RESOLVER_DEFAULT_MAX_SAMPLES; |
| } |
| } |
| |
| private int getIntSetting(String which, int dflt) { |
| return Settings.Global.getInt(mContentResolver, which, dflt); |
| } |
| |
| private void setNetDnsProperty(int which, String value) { |
| final String key = "net.dns" + which; |
| // Log and forget errors setting unsupported properties. |
| try { |
| mSystemProperties.set(key, value); |
| } catch (Exception e) { |
| Slog.e(TAG, "Error setting unsupported net.dns property: ", e); |
| } |
| } |
| |
| private static String getPrivateDnsMode(ContentResolver cr) { |
| String mode = getStringSetting(cr, PRIVATE_DNS_MODE); |
| if (TextUtils.isEmpty(mode)) mode = getStringSetting(cr, PRIVATE_DNS_DEFAULT_MODE); |
| if (TextUtils.isEmpty(mode)) mode = PRIVATE_DNS_DEFAULT_MODE_FALLBACK; |
| return mode; |
| } |
| |
| private static String getStringSetting(ContentResolver cr, String which) { |
| return Settings.Global.getString(cr, which); |
| } |
| |
| private static String[] getDomainStrings(String domains) { |
| return (TextUtils.isEmpty(domains)) ? new String[0] : domains.split(" "); |
| } |
| } |