Drop packets to VPN address ingressing via non-VPN interface
Cherry-pick of aosp/2795711 to backport VPN security fix to non-mainline
U devices.
Since isTetheringFeatureNotChickenedOut is not available on U branch,
this feature is enabled on T+ devices without kill switch.
Also, this CL removes test changes since CSTest utilities are not
available on u branches.
When there are addresses that are used by a single VPN interface,
ConnectivityService sets ingress discard rules to drop packets to this
address from the non-Vpn interfaces
Bug: 193031925
Test: TH
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:d493a3aa7dcca3219b139616c9de3c6ee8181f86)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:1027bc813ea6a5b97bc0f55401e01f5eec91e94a)
Merged-In: I5933d42f3fd257139fb803ede1391e10d9d1211b
Change-Id: I5933d42f3fd257139fb803ede1391e10d9d1211b
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 120486c1..0882870 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -936,6 +936,9 @@
private final Map<String, ApplicationSelfCertifiedNetworkCapabilities>
mSelfCertifiedCapabilityCache = new HashMap<>();
+ // Flag to drop packets to VPN addresses ingressing via non-VPN interfaces.
+ private final boolean mIngressToVpnAddressFiltering;
+
/**
* Implements support for the legacy "one network per network type" model.
*
@@ -1798,6 +1801,7 @@
activityManager.registerUidFrozenStateChangedCallback(
(Runnable r) -> r.run(), frozenStateChangedCallback);
}
+ mIngressToVpnAddressFiltering = mDeps.isAtLeastT();
}
/**
@@ -4776,6 +4780,7 @@
if (mDscpPolicyTracker != null) {
mDscpPolicyTracker.removeAllDscpPolicies(nai, false);
}
+ updateIngressToVpnAddressFiltering(null, nai.linkProperties, nai);
try {
mNetd.networkDestroy(nai.network.getNetId());
} catch (RemoteException | ServiceSpecificException e) {
@@ -8014,6 +8019,8 @@
// new interface (the interface name -> index map becomes initialized)
updateVpnFiltering(newLp, oldLp, networkAgent);
+ updateIngressToVpnAddressFiltering(newLp, oldLp, networkAgent);
+
updateMtu(newLp, oldLp);
// TODO - figure out what to do for clat
// for (LinkProperties lp : newLp.getStackedLinks()) {
@@ -8337,6 +8344,87 @@
}
}
+ /**
+ * Returns ingress discard rules to drop packets to VPN addresses ingressing via non-VPN
+ * interfaces.
+ * Ingress discard rule is added to the address iff
+ * 1. The address is not a link local address
+ * 2. The address is used by a single VPN interface and not used by any other
+ * interfaces even non-VPN ones
+ * This method can be called during network disconnects, when nai has already been removed from
+ * mNetworkAgentInfos.
+ *
+ * @param nai This method generates rules assuming lp of this nai is the lp at the second
+ * argument.
+ * @param lp This method generates rules assuming lp of nai at the first argument is this lp.
+ * Caller passes old lp to generate old rules and new lp to generate new rules.
+ * @return ingress discard rules. Set of pairs of addresses and interface names
+ */
+ private Set<Pair<InetAddress, String>> generateIngressDiscardRules(
+ @NonNull final NetworkAgentInfo nai, @Nullable final LinkProperties lp) {
+ Set<NetworkAgentInfo> nais = new ArraySet<>(mNetworkAgentInfos);
+ nais.add(nai);
+ // Determine how many networks each IP address is currently configured on.
+ // Ingress rules are added only for IP addresses that are configured on single interface.
+ final Map<InetAddress, Integer> addressOwnerCounts = new ArrayMap<>();
+ for (final NetworkAgentInfo agent : nais) {
+ if (agent.isDestroyed()) {
+ continue;
+ }
+ final LinkProperties agentLp = (nai == agent) ? lp : agent.linkProperties;
+ if (agentLp == null) {
+ continue;
+ }
+ for (final InetAddress addr: agentLp.getAllAddresses()) {
+ addressOwnerCounts.put(addr, addressOwnerCounts.getOrDefault(addr, 0) + 1);
+ }
+ }
+
+ // Iterates all networks instead of only generating rule for nai that was passed in since
+ // lp of the nai change could cause/resolve address collision and result in affecting rule
+ // for different network.
+ final Set<Pair<InetAddress, String>> ingressDiscardRules = new ArraySet<>();
+ for (final NetworkAgentInfo agent : nais) {
+ if (!agent.isVPN() || agent.isDestroyed()) {
+ continue;
+ }
+ final LinkProperties agentLp = (nai == agent) ? lp : agent.linkProperties;
+ if (agentLp == null || agentLp.getInterfaceName() == null) {
+ continue;
+ }
+
+ for (final InetAddress addr: agentLp.getAllAddresses()) {
+ if (addressOwnerCounts.get(addr) == 1 && !addr.isLinkLocalAddress()) {
+ ingressDiscardRules.add(new Pair<>(addr, agentLp.getInterfaceName()));
+ }
+ }
+ }
+ return ingressDiscardRules;
+ }
+
+ private void updateIngressToVpnAddressFiltering(@Nullable LinkProperties newLp,
+ @Nullable LinkProperties oldLp, @NonNull NetworkAgentInfo nai) {
+ // Having isAtleastT to avoid NewApi linter error (b/303382209)
+ if (!mIngressToVpnAddressFiltering || !mDeps.isAtLeastT()) {
+ return;
+ }
+ final CompareOrUpdateResult<InetAddress, Pair<InetAddress, String>> ruleDiff =
+ new CompareOrUpdateResult<>(
+ generateIngressDiscardRules(nai, oldLp),
+ generateIngressDiscardRules(nai, newLp),
+ (rule) -> rule.first);
+ for (Pair<InetAddress, String> rule: ruleDiff.removed) {
+ mBpfNetMaps.removeIngressDiscardRule(rule.first);
+ }
+ for (Pair<InetAddress, String> rule: ruleDiff.added) {
+ mBpfNetMaps.setIngressDiscardRule(rule.first, rule.second);
+ }
+ // setIngressDiscardRule overrides the existing rule
+ for (Pair<InetAddress, String> rule: ruleDiff.updated) {
+ mBpfNetMaps.setIngressDiscardRule(rule.first, rule.second);
+ }
+ }
+
private void updateWakeOnLan(@NonNull LinkProperties lp) {
if (mWolSupportedInterfaces == null) {
mWolSupportedInterfaces = new ArraySet<>(mResources.get().getStringArray(
