commit cb448f5c783c47a82528dbc55b93fcdd972e172a
author Motomu Utsumi <motomuman@google.com> Fri Mar 22 19:34:38 2024 +0900
committer Motomu Utsumi <motomuman@google.com> Tue Mar 26 19:16:54 2024 +0900
tree 6ed275b2073523380f9dc11befbad752561845d3
parent 619c41c01c936de055455dfb16505c8d4a314ca6

Fix isUidNetworkingBlocked for system uids

Update isUidNetworkingBlocked to return false for system uids regardless
of firewall chain status since this is an actual behavior

Bug: 328732146
Test: TH
Change-Id: Ic4760b927f51a1229e9af09c79b5261f85fe89d1

framework/src/android/net/BpfNetMapsUtils.java

diff --git a/framework/src/android/net/BpfNetMapsUtils.java b/framework/src/android/net/BpfNetMapsUtils.java
index 3c91db2..19ecafb 100644
--- a/framework/src/android/net/BpfNetMapsUtils.java
+++ b/framework/src/android/net/BpfNetMapsUtils.java
@@ -47,6 +47,7 @@
 import static android.net.ConnectivityManager.FIREWALL_RULE_DENY;
 import static android.system.OsConstants.EINVAL;
 
+import android.os.Process;
 import android.os.ServiceSpecificException;
 import android.system.ErrnoException;
 import android.system.Os;
@@ -239,6 +240,12 @@
     ) {
         throwIfPreT("isUidBlockedByFirewallChains is not available on pre-T devices");
 
+        // System uid is not blocked by firewall chains, see bpf_progs/netd.c
+        // TODO: use UserHandle.isCore() once it is accessible
+        if (uid < Process.FIRST_APPLICATION_UID) {
+            return false;
+        }
+
         final long uidRuleConfig;
         final long uidMatch;
         try {

tests/unit/java/android/net/NetworkStackBpfNetMapsTest.kt

diff --git a/tests/unit/java/android/net/NetworkStackBpfNetMapsTest.kt b/tests/unit/java/android/net/NetworkStackBpfNetMapsTest.kt
index ca98269..a9ccbdd 100644
--- a/tests/unit/java/android/net/NetworkStackBpfNetMapsTest.kt
+++ b/tests/unit/java/android/net/NetworkStackBpfNetMapsTest.kt
@@ -26,6 +26,7 @@
 import android.net.BpfNetMapsConstants.UID_RULES_CONFIGURATION_KEY
 import android.net.BpfNetMapsUtils.getMatchByFirewallChain
 import android.os.Build.VERSION_CODES
+import android.os.Process.FIRST_APPLICATION_UID
 import com.android.net.module.util.IBpfMap
 import com.android.net.module.util.Struct.S32
 import com.android.net.module.util.Struct.U32
@@ -42,7 +43,7 @@
 import org.junit.Test
 import org.junit.runner.RunWith
 
-private const val TEST_UID1 = 1234
+private const val TEST_UID1 = 11234
 private const val TEST_UID2 = TEST_UID1 + 1
 private const val TEST_UID3 = TEST_UID2 + 1
 private const val NO_IIF = 0
@@ -231,6 +232,24 @@
     }
 
     @Test
+    fun testIsUidNetworkingBlocked_SystemUid() {
+        mockDataSaverEnabled(enabled = false)
+        testConfigurationMap.updateEntry(UID_RULES_CONFIGURATION_KEY, U32(0))
+        mockChainEnabled(ConnectivityManager.FIREWALL_CHAIN_DOZABLE, true)
+
+        for (uid in FIRST_APPLICATION_UID - 5..FIRST_APPLICATION_UID + 5) {
+            // system uid is not blocked regardless of firewall chains
+            val expectBlocked = uid >= FIRST_APPLICATION_UID
+            testUidOwnerMap.updateEntry(S32(uid), UidOwnerValue(NO_IIF, PENALTY_BOX_MATCH))
+            assertEquals(
+                expectBlocked,
+                    isUidNetworkingBlocked(uid, metered = true),
+                    "isUidNetworkingBlocked returns unexpected value for uid = " + uid
+            )
+        }
+    }
+
+    @Test
     fun testGetDataSaverEnabled() {
         testDataSaverEnabledMap.updateEntry(DATA_SAVER_ENABLED_KEY, U8(DATA_SAVER_DISABLED))
         assertFalse(bpfNetMapsReader.dataSaverEnabled)