Add helper method to enfore a package name belongs to an uid

This is no-op refactor to move utility methods from
ConnectivityService to a common place.

Test: atest NetworkStaticLibTests#com.android.net.moduletests.util.PermissionUtilsTest#testEnforcePackageNameMatchesUid
Bug: N/A
Change-Id: I5802dedcc91fa6e130a5c534bba5080ca37dbeec
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 7339d08..66e10a2 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -3004,26 +3004,6 @@
         return false;
     }
 
-    private int getAppUid(final String app, final UserHandle user) {
-        final PackageManager pm =
-                mContext.createContextAsUser(user, 0 /* flags */).getPackageManager();
-        final long token = Binder.clearCallingIdentity();
-        try {
-            return pm.getPackageUid(app, 0 /* flags */);
-        } catch (PackageManager.NameNotFoundException e) {
-            return -1;
-        } finally {
-            Binder.restoreCallingIdentity(token);
-        }
-    }
-
-    private void verifyCallingUidAndPackage(String packageName, int callingUid) {
-        final UserHandle user = UserHandle.getUserHandleForUid(callingUid);
-        if (getAppUid(packageName, user) != callingUid) {
-            throw new SecurityException(packageName + " does not belong to uid " + callingUid);
-        }
-    }
-
     /**
      * Ensure that a network route exists to deliver traffic to the specified
      * host via the specified network interface.
@@ -3039,7 +3019,8 @@
         if (disallowedBecauseSystemCaller()) {
             return false;
         }
-        verifyCallingUidAndPackage(callingPackageName, mDeps.getCallingUid());
+        PermissionUtils.enforcePackageNameMatchesUid(
+                mContext, mDeps.getCallingUid(), callingPackageName);
         enforceChangePermission(callingPackageName, callingAttributionTag);
         if (mProtectedNetworks.contains(networkType)) {
             enforceConnectivityRestrictedNetworksPermission(true /* checkUidsAllowedList */);
diff --git a/staticlibs/framework/com/android/net/module/util/PermissionUtils.java b/staticlibs/framework/com/android/net/module/util/PermissionUtils.java
index 8315b8f..f167d3d 100644
--- a/staticlibs/framework/com/android/net/module/util/PermissionUtils.java
+++ b/staticlibs/framework/com/android/net/module/util/PermissionUtils.java
@@ -27,7 +27,9 @@
 import android.annotation.Nullable;
 import android.content.Context;
 import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
 import android.os.Binder;
+import android.os.UserHandle;
 
 import java.io.PrintWriter;
 import java.util.ArrayList;
@@ -183,4 +185,33 @@
         }
         return result;
     }
+
+    /**
+     * Enforces that the given package name belongs to the given uid.
+     *
+     * @param context {@link android.content.Context} for the process.
+     * @param uid User ID to check the package ownership for.
+     * @param packageName Package name to verify.
+     * @throws SecurityException If the package does not belong to the specified uid.
+     */
+    public static void enforcePackageNameMatchesUid(
+            @NonNull Context context, int uid, @Nullable String packageName) {
+        final UserHandle user = UserHandle.getUserHandleForUid(uid);
+        if (getAppUid(context, packageName, user) != uid) {
+            throw new SecurityException(packageName + " does not belong to uid " + uid);
+        }
+    }
+
+    private static int getAppUid(Context context, final String app, final UserHandle user) {
+        final PackageManager pm =
+                context.createContextAsUser(user, 0 /* flags */).getPackageManager();
+        final long token = Binder.clearCallingIdentity();
+        try {
+            return pm.getPackageUid(app, 0 /* flags */);
+        } catch (PackageManager.NameNotFoundException e) {
+            return -1;
+        } finally {
+            Binder.restoreCallingIdentity(token);
+        }
+    }
 }
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/PermissionUtilsTest.kt b/staticlibs/tests/unit/src/com/android/net/module/util/PermissionUtilsTest.kt
index c5a91a4..d5b43fb 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/PermissionUtilsTest.kt
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/PermissionUtilsTest.kt
@@ -19,6 +19,7 @@
 import android.Manifest.permission.NETWORK_STACK
 import android.content.Context
 import android.content.pm.PackageManager
+import android.content.pm.PackageManager.NameNotFoundException
 import android.content.pm.PackageManager.PERMISSION_DENIED
 import android.content.pm.PackageManager.PERMISSION_GRANTED
 import android.net.NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK
@@ -28,6 +29,7 @@
 import com.android.net.module.util.PermissionUtils.enforceAnyPermissionOf
 import com.android.net.module.util.PermissionUtils.enforceNetworkStackPermission
 import com.android.net.module.util.PermissionUtils.enforceNetworkStackPermissionOr
+import com.android.net.module.util.PermissionUtils.enforcePackageNameMatchesUid
 import com.android.net.module.util.PermissionUtils.enforceSystemFeature
 import com.android.testutils.DevSdkIgnoreRule
 import com.android.testutils.DevSdkIgnoreRunner
@@ -42,7 +44,10 @@
 import org.junit.runner.RunWith
 import org.mockito.ArgumentMatchers
 import org.mockito.ArgumentMatchers.any
+import org.mockito.ArgumentMatchers.anyInt
+import org.mockito.ArgumentMatchers.eq
 import org.mockito.Mockito.doReturn
+import org.mockito.Mockito.doThrow
 import org.mockito.Mockito.mock
 
 /** Tests for PermissionUtils */
@@ -53,6 +58,9 @@
     val ignoreRule = DevSdkIgnoreRule()
     private val TEST_PERMISSION1 = "android.permission.TEST_PERMISSION1"
     private val TEST_PERMISSION2 = "android.permission.TEST_PERMISSION2"
+    private val TEST_UID1 = 1234
+    private val TEST_UID2 = 1235
+    private val TEST_PACKAGE_NAME = "test.package"
     private val mockContext = mock(Context::class.java)
     private val mockPackageManager = mock(PackageManager::class.java)
 
@@ -61,6 +69,7 @@
     @Before
     fun setup() {
         doReturn(mockPackageManager).`when`(mockContext).packageManager
+        doReturn(mockContext).`when`(mockContext).createContextAsUser(any(), anyInt())
     }
 
     @Test
@@ -141,4 +150,24 @@
             Assert.fail("Exception should have not been thrown with system feature enabled")
         }
     }
+
+    @Test
+    fun testEnforcePackageNameMatchesUid() {
+        // Verify name not found throws.
+        doThrow(NameNotFoundException()).`when`(mockPackageManager)
+            .getPackageUid(eq(TEST_PACKAGE_NAME), anyInt())
+        assertFailsWith<SecurityException> {
+            enforcePackageNameMatchesUid(mockContext, TEST_UID1, TEST_PACKAGE_NAME)
+        }
+
+        // Verify uid mismatch throws.
+        doReturn(TEST_UID1).`when`(mockPackageManager)
+            .getPackageUid(eq(TEST_PACKAGE_NAME), anyInt())
+        assertFailsWith<SecurityException> {
+            enforcePackageNameMatchesUid(mockContext, TEST_UID2, TEST_PACKAGE_NAME)
+        }
+
+        // Verify uid match passes.
+        enforcePackageNameMatchesUid(mockContext, TEST_UID1, TEST_PACKAGE_NAME)
+    }
 }