[BR01.1] Support BpfNetMapsReader
A helper class to *read* java BpfMaps. This is designed to
provide direct bpf access in the caller process through
ConnectivityManager APIs.
The change also removes any statical link to
net-utils-device-common-struct from service-connectivity.
This is because net-utils-device-common-struct is already
included in framework-connectivity. Including it again in
service-connectivity would create a r8 build fail by circular
dependency.
Test: atest FrameworksNetTests:android.net.connectivity.com.android.server.BpfNetMapsTest
Test: atest ConnectivityCoverageTests:android.net.connectivity.com.android.net.module.util.StructTest
Test: atest FrameworksNetTests:android.net.connectivity.android.net.BpfNetMapsReaderTest
Bug: 297836825
Change-Id: I7a6d2eb816d0dc7343167bddd672806b199f44fe
diff --git a/framework/Android.bp b/framework/Android.bp
index 182c558..449e652 100644
--- a/framework/Android.bp
+++ b/framework/Android.bp
@@ -101,7 +101,7 @@
"framework-connectivity-javastream-protos",
],
impl_only_static_libs: [
- "net-utils-device-common-struct",
+ "net-utils-device-common-bpf",
],
libs: [
"androidx.annotation_annotation",
@@ -130,7 +130,7 @@
// to generate the SDK stubs.
// Even if the library is included in "impl_only_static_libs" of defaults. This is still
// needed because java_library which doesn't understand "impl_only_static_libs".
- "net-utils-device-common-struct",
+ "net-utils-device-common-bpf",
],
libs: [
// This cannot be in the defaults clause above because if it were, it would be used
diff --git a/framework/src/android/net/BpfNetMapsReader.java b/framework/src/android/net/BpfNetMapsReader.java
new file mode 100644
index 0000000..49e874a
--- /dev/null
+++ b/framework/src/android/net/BpfNetMapsReader.java
@@ -0,0 +1,179 @@
+/*
+ * Copyright (C) 2023 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 android.net;
+
+import static android.net.BpfNetMapsConstants.CONFIGURATION_MAP_PATH;
+import static android.net.BpfNetMapsConstants.UID_OWNER_MAP_PATH;
+import static android.net.BpfNetMapsConstants.UID_RULES_CONFIGURATION_KEY;
+import static android.net.BpfNetMapsUtils.getMatchByFirewallChain;
+import static android.net.BpfNetMapsUtils.isFirewallAllowList;
+import static android.net.BpfNetMapsUtils.throwIfPreT;
+import static android.net.ConnectivityManager.FIREWALL_RULE_ALLOW;
+import static android.net.ConnectivityManager.FIREWALL_RULE_DENY;
+
+import android.annotation.NonNull;
+import android.annotation.RequiresApi;
+import android.os.Build;
+import android.os.ServiceSpecificException;
+import android.system.ErrnoException;
+import android.system.Os;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.modules.utils.build.SdkLevel;
+import com.android.net.module.util.BpfMap;
+import com.android.net.module.util.IBpfMap;
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.S32;
+import com.android.net.module.util.Struct.U32;
+
+/**
+ * A helper class to *read* java BpfMaps.
+ * @hide
+ */
+@RequiresApi(Build.VERSION_CODES.TIRAMISU) // BPF maps were only mainlined in T
+public class BpfNetMapsReader {
+ // Locally store the handle of bpf maps. The FileDescriptors are statically cached inside the
+ // BpfMap implementation.
+
+ // Bpf map to store various networking configurations, the format of the value is different
+ // for different keys. See BpfNetMapsConstants#*_CONFIGURATION_KEY for keys.
+ private final IBpfMap<S32, U32> mConfigurationMap;
+ // Bpf map to store per uid traffic control configurations.
+ // See {@link UidOwnerValue} for more detail.
+ private final IBpfMap<S32, UidOwnerValue> mUidOwnerMap;
+ private final Dependencies mDeps;
+
+ public BpfNetMapsReader() {
+ this(new Dependencies());
+ }
+
+ @VisibleForTesting
+ public BpfNetMapsReader(@NonNull Dependencies deps) {
+ if (!SdkLevel.isAtLeastT()) {
+ throw new UnsupportedOperationException(
+ BpfNetMapsReader.class.getSimpleName() + " is not supported below Android T");
+ }
+ mDeps = deps;
+ mConfigurationMap = mDeps.getConfigurationMap();
+ mUidOwnerMap = mDeps.getUidOwnerMap();
+ }
+
+ /**
+ * Dependencies of BpfNetMapReader, for injection in tests.
+ */
+ @VisibleForTesting
+ public static class Dependencies {
+ /** Get the configuration map. */
+ public IBpfMap<S32, U32> getConfigurationMap() {
+ try {
+ return new BpfMap<>(CONFIGURATION_MAP_PATH, BpfMap.BPF_F_RDONLY,
+ S32.class, U32.class);
+ } catch (ErrnoException e) {
+ throw new IllegalStateException("Cannot open configuration map", e);
+ }
+ }
+
+ /** Get the uid owner map. */
+ public IBpfMap<S32, UidOwnerValue> getUidOwnerMap() {
+ try {
+ return new BpfMap<>(UID_OWNER_MAP_PATH, BpfMap.BPF_F_RDONLY,
+ S32.class, UidOwnerValue.class);
+ } catch (ErrnoException e) {
+ throw new IllegalStateException("Cannot open uid owner map", e);
+ }
+ }
+ }
+
+ /**
+ * Get the specified firewall chain's status.
+ *
+ * @param chain target chain
+ * @return {@code true} if chain is enabled, {@code false} if chain is not enabled.
+ * @throws UnsupportedOperationException if called on pre-T devices.
+ * @throws ServiceSpecificException in case of failure, with an error code indicating the
+ * cause of the failure.
+ */
+ public boolean isChainEnabled(final int chain) {
+ return isChainEnabled(mConfigurationMap, chain);
+ }
+
+ /**
+ * Get firewall rule of specified firewall chain on specified uid.
+ *
+ * @param chain target chain
+ * @param uid target uid
+ * @return either {@link ConnectivityManager#FIREWALL_RULE_ALLOW} or
+ * {@link ConnectivityManager#FIREWALL_RULE_DENY}.
+ * @throws UnsupportedOperationException if called on pre-T devices.
+ * @throws ServiceSpecificException in case of failure, with an error code indicating the
+ * cause of the failure.
+ */
+ public int getUidRule(final int chain, final int uid) {
+ return getUidRule(mUidOwnerMap, chain, uid);
+ }
+
+ /**
+ * Get the specified firewall chain's status.
+ *
+ * @param configurationMap target configurationMap
+ * @param chain target chain
+ * @return {@code true} if chain is enabled, {@code false} if chain is not enabled.
+ * @throws UnsupportedOperationException if called on pre-T devices.
+ * @throws ServiceSpecificException in case of failure, with an error code indicating the
+ * cause of the failure.
+ */
+ public static boolean isChainEnabled(
+ final IBpfMap<Struct.S32, Struct.U32> configurationMap, final int chain) {
+ throwIfPreT("isChainEnabled is not available on pre-T devices");
+
+ final long match = getMatchByFirewallChain(chain);
+ try {
+ final Struct.U32 config = configurationMap.getValue(UID_RULES_CONFIGURATION_KEY);
+ return (config.val & match) != 0;
+ } catch (ErrnoException e) {
+ throw new ServiceSpecificException(e.errno,
+ "Unable to get firewall chain status: " + Os.strerror(e.errno));
+ }
+ }
+
+ /**
+ * Get firewall rule of specified firewall chain on specified uid.
+ *
+ * @param uidOwnerMap target uidOwnerMap.
+ * @param chain target chain.
+ * @param uid target uid.
+ * @return either FIREWALL_RULE_ALLOW or FIREWALL_RULE_DENY
+ * @throws UnsupportedOperationException if called on pre-T devices.
+ * @throws ServiceSpecificException in case of failure, with an error code indicating the
+ * cause of the failure.
+ */
+ public static int getUidRule(final IBpfMap<Struct.S32, UidOwnerValue> uidOwnerMap,
+ final int chain, final int uid) {
+ throwIfPreT("getUidRule is not available on pre-T devices");
+
+ final long match = getMatchByFirewallChain(chain);
+ final boolean isAllowList = isFirewallAllowList(chain);
+ try {
+ final UidOwnerValue uidMatch = uidOwnerMap.getValue(new Struct.S32(uid));
+ final boolean isMatchEnabled = uidMatch != null && (uidMatch.rule & match) != 0;
+ return isMatchEnabled == isAllowList ? FIREWALL_RULE_ALLOW : FIREWALL_RULE_DENY;
+ } catch (ErrnoException e) {
+ throw new ServiceSpecificException(e.errno,
+ "Unable to get uid rule status: " + Os.strerror(e.errno));
+ }
+ }
+}
diff --git a/framework/src/android/net/BpfNetMapsUtils.java b/framework/src/android/net/BpfNetMapsUtils.java
index d464e3d..28d5891 100644
--- a/framework/src/android/net/BpfNetMapsUtils.java
+++ b/framework/src/android/net/BpfNetMapsUtils.java
@@ -39,6 +39,8 @@
import android.os.ServiceSpecificException;
import android.util.Pair;
+import com.android.modules.utils.build.SdkLevel;
+
import java.util.StringJoiner;
/**
@@ -124,4 +126,15 @@
}
return sj.toString();
}
+
+ public static final boolean PRE_T = !SdkLevel.isAtLeastT();
+
+ /**
+ * Throw UnsupportedOperationException if SdkLevel is before T.
+ */
+ public static void throwIfPreT(final String msg) {
+ if (PRE_T) {
+ throw new UnsupportedOperationException(msg);
+ }
+ }
}
diff --git a/framework/src/android/net/UidOwnerValue.java b/framework/src/android/net/UidOwnerValue.java
new file mode 100644
index 0000000..e8ae604
--- /dev/null
+++ b/framework/src/android/net/UidOwnerValue.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2023 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 android.net;
+
+import com.android.net.module.util.Struct;
+
+/**
+ * Value type for per uid traffic control configuration map.
+ *
+ * @hide
+ */
+public class UidOwnerValue extends Struct {
+ // Allowed interface index. Only applicable if IIF_MATCH is set in the rule bitmask below.
+ @Field(order = 0, type = Type.S32)
+ public final int iif;
+
+ // A bitmask of match type.
+ @Field(order = 1, type = Type.U32)
+ public final long rule;
+
+ public UidOwnerValue(final int iif, final long rule) {
+ this.iif = iif;
+ this.rule = rule;
+ }
+}