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Always drop non-VPN ingress in lockdown mode

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When "Block connections without VPN" is specified, incoming traffic
from non-VPN interfaces should be blocked regardless of the
determination made by ConnectivityService#getVpnIsolationInterface.
Outgoing traffic to non-VPN interfaces is already blocked in this case.
(Loopback is excluded as usual.)

Test: `adb shell dumpsys connectivity trafficcontroller` will now show
the tunnel interface for uids affected by lockdown when
getVpnIsolationInterface returns null (wildcard), to block non-VPN
ingress to such uids. This will return to 0 (wildcard) when lockdown
is toggled back off.

Also includes squashed change:

Author: Tommy Webb <tommy@calyxinstitute.org>
Date:   Mon May 1 16:52:28 2023 -0400

    fixup! Always drop non-VPN ingress in lockdown mode

    For lockdown purposes, force an update of VPN filtering whenever the
    interface names for a VPN have changed, to ensure that the BPF owner
    map uses the most up-to-date interface for ingress filtering.

    Issue: calyxos#1651
    Change-Id: Ia0c75a723134023906134597b395653c7a570686

Co-authored-by: Tommy Webb <tommy@calyxinstitute.org>
Issue: calyxos#1255
Bug: 206482423
Change-Id: Id7954816566cb06bf2e9869ea98b20678835df9d
This commit is contained in:
Oliver Scott 2022-10-27 23:52:45 +00:00 • committed by Thomas Turner
commit 19f95c26ad
2 changed files with 61 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

31
service/src/com/android/server/ConnectivityService.java
View file

@ -7954,6 +7954,10 @@ public class ConnectivityService extends IConnectivityManager.Stub {
final boolean curMetered = nai.networkCapabilities.isMetered();
maybeNotifyNetworkBlocked(nai, curMetered, curMetered,
mVpnBlockedUidRanges, newVpnBlockedUidRanges);
if (nai.isVPN()) {
updateVpnFiltering(nai.linkProperties, nai.linkProperties, nai, true /* force */);
}
});
mVpnBlockedUidRanges = newVpnBlockedUidRanges;
@ -10090,11 +10094,16 @@ public class ConnectivityService extends IConnectivityManager.Stub {
// the LinkProperties for the network are accurate.
networkAgent.clatd.fixupLinkProperties(oldLp, newLp);
updateInterfaces(newLp, oldLp, netId, networkAgent);
final boolean anyIfaceChanges =
updateInterfaces(newLp, oldLp, netId, networkAgent);
// If any interface names changed, ensure VPN filtering is updated so that ingress filtering
// uses the most up-to-date allowed interface.
final boolean shouldForceUpdateVpnFiltering = networkAgent.isVPN() && anyIfaceChanges;
// update filtering rules, need to happen after the interface update so netd knows about the
// new interface (the interface name -> index map becomes initialized)
updateVpnFiltering(newLp, oldLp, networkAgent);
updateVpnFiltering(newLp, oldLp, networkAgent, shouldForceUpdateVpnFiltering);
updateIngressToVpnAddressFiltering(newLp, oldLp, networkAgent);
@ -10247,7 +10256,8 @@ public class ConnectivityService extends IConnectivityManager.Stub {
}
}
private void updateInterfaces(final @NonNull LinkProperties newLp,
/** Return whether there were any added or removed interface names. */
private boolean updateInterfaces(final @NonNull LinkProperties newLp,
final @Nullable LinkProperties oldLp, final int netId,
final @NonNull NetworkAgentInfo nai) {
final CompareResult<String> interfaceDiff = new CompareResult<>(
@ -10281,6 +10291,7 @@ public class ConnectivityService extends IConnectivityManager.Stub {
loge("Exception removing interface: " + e);
}
}
return !(interfaceDiff.added.isEmpty() && interfaceDiff.removed.isEmpty());
}
/**
@ -10569,7 +10580,7 @@ public class ConnectivityService extends IConnectivityManager.Stub {
}
private void updateVpnFiltering(@NonNull LinkProperties newLp, @Nullable LinkProperties oldLp,
@NonNull NetworkAgentInfo nai) {
@NonNull NetworkAgentInfo nai, boolean force) {
final String oldIface = getVpnIsolationInterface(nai, nai.networkCapabilities, oldLp);
final String newIface = getVpnIsolationInterface(nai, nai.networkCapabilities, newLp);
final boolean wasFiltering = requiresVpnAllowRule(nai, oldLp, oldIface);
@ -10580,7 +10591,7 @@ public class ConnectivityService extends IConnectivityManager.Stub {
return;
}
if (Objects.equals(oldIface, newIface) && (wasFiltering == needsFiltering)) {
if (!force && Objects.equals(oldIface, newIface) && (wasFiltering == needsFiltering)) {
// Nothing changed.
return;
}
@ -10597,9 +10608,13 @@ public class ConnectivityService extends IConnectivityManager.Stub {
// old rules are being removed.
if (wasFiltering) {
mPermissionMonitor.onVpnUidRangesRemoved(oldIface, ranges, vpnAppUid);
mPermissionMonitor.updateVpnLockdownUidInterfaceRules(oldLp.getInterfaceName(), ranges,
vpnAppUid, false /* add */);
}
if (needsFiltering) {
mPermissionMonitor.onVpnUidRangesAdded(newIface, ranges, vpnAppUid);
mPermissionMonitor.updateVpnLockdownUidInterfaceRules(newLp.getInterfaceName(), ranges,
vpnAppUid, true /* add */);
}
}
@ -11339,9 +11354,15 @@ public class ConnectivityService extends IConnectivityManager.Stub {
if (wasFiltering && !prevRanges.isEmpty()) {
mPermissionMonitor.onVpnUidRangesRemoved(oldIface, prevRanges,
prevNc.getOwnerUid());
mPermissionMonitor.updateVpnLockdownUidInterfaceRules(
nai.linkProperties.getInterfaceName(), prevRanges, prevNc.getOwnerUid(),
false /* add */);
}
if (shouldFilter && !newRanges.isEmpty()) {
mPermissionMonitor.onVpnUidRangesAdded(newIface, newRanges, newNc.getOwnerUid());
mPermissionMonitor.updateVpnLockdownUidInterfaceRules(
nai.linkProperties.getInterfaceName(), newRanges, newNc.getOwnerUid(),
true /* add */);
}
} catch (Exception e) {
// Never crash!

35
service/src/com/android/server/connectivity/PermissionMonitor.java
View file

@ -1025,6 +1025,7 @@ public class PermissionMonitor {
// packets to that UID is fine.
final Set<Integer> changedUids = intersectUids(rangesToAdd, mAllApps);
removeBypassingUids(changedUids, vpnAppUid);
removeVpnLockdownUids(iface, changedUids);
updateVpnUidsInterfaceRules(iface, changedUids, true /* add */);
if (mVpnInterfaceUidRanges.containsKey(iface)) {
mVpnInterfaceUidRanges.get(iface).addAll(rangesToAdd);
@ -1047,6 +1048,7 @@ public class PermissionMonitor {
// ranges and update Netd about them.
final Set<Integer> changedUids = intersectUids(rangesToRemove, mAllApps);
removeBypassingUids(changedUids, vpnAppUid);
removeVpnLockdownUids(iface, changedUids);
updateVpnUidsInterfaceRules(iface, changedUids, false /* add */);
Set<UidRange> existingRanges = mVpnInterfaceUidRanges.getOrDefault(iface, null);
if (existingRanges == null) {
@ -1059,6 +1061,27 @@ public class PermissionMonitor {
}
}
/**
* Called when a set of UID ranges are added/removed from an active VPN network and when
* UID ranges under VPN Lockdown are updated
*
* @param iface The VPN network's interface name. Null iface indicates that the interface is not
* available.
* @param rangesToModify Existing UID ranges to be modified on the VPN network
* @param add {@code true} to add the UID rules, {@code false} to remove them.
* @param vpnAppUid The uid of the VPN app
*/
public synchronized void updateVpnLockdownUidInterfaceRules(@Nullable String iface,
Set<UidRange> rangesToModify, int vpnAppUid, boolean add) {
if (iface != null) {
Set<Integer> uidsToModify = intersectUids(rangesToModify, mAllApps);
removeBypassingUids(uidsToModify, vpnAppUid);
Set<Integer> vpnLockdownUids = intersectUids(mVpnLockdownUidRanges.getSet(), mAllApps);
uidsToModify.retainAll(vpnLockdownUids);
updateVpnUidsInterfaceRules(iface, uidsToModify, add);
}
}
/**
* Called when UID ranges under VPN Lockdown are updated
*
@ -1147,6 +1170,18 @@ public class PermissionMonitor {
uids.removeIf(this::hasRestrictedNetworksPermission);
}
/**
* Remove all apps which are under VPN Lockdown from the list of uids
*
* @param iface The interface name of the active VPN connection
* @param uids The list of uids to operate on
*/
private void removeVpnLockdownUids(@Nullable String iface, Set<Integer> uids) {
if (iface == null) {
uids.removeAll(intersectUids(mVpnLockdownUidRanges.getSet(), mAllApps));
}
}
/**
* Update netd about the list of uids that are under an active VPN connection which they cannot
* bypass.