Relax global restrict for system services.

Since we control system services, we can ensure they are using little
data when data usage is globally restricted.  Continue restricting
AID_MEDIA and AID_DRM, since they respond to app requests.

Bug: 6377903, 5772564
Change-Id: I196bf334f903397ea6a67e6802240ee792e47b54

Author: jsharkey

core/java/android/os/Process.java

@@ -91,6 +91,12 @@ public class Process {
      */
     public static final int MEDIA_UID = 1013;
 
+    /**
+     * Defines the UID/GID for the DRM process.
+     * @hide
+     */
+    public static final int DRM_UID = 1019;
+
     /**
      * Defines the GID for the group that allows write access to the SD card.
      * @hide

services/java/com/android/server/net/NetworkPolicyManagerService.java

@@ -1665,20 +1665,9 @@ private void updateRulesForRestrictBackgroundLocked() {
             updateRulesForAppLocked(appId);
         }
 
-        // and catch system UIDs
-        // TODO: keep in sync with android_filesystem_config.h
-        for (int uid = 1000; uid <= 1025; uid++) {
-            updateRulesForUidLocked(uid);
-        }
-        for (int uid = 2000; uid <= 2002; uid++) {
-            updateRulesForUidLocked(uid);
-        }
-        for (int uid = 3000; uid <= 3007; uid++) {
-            updateRulesForUidLocked(uid);
-        }
-        for (int uid = 9998; uid <= 9999; uid++) {
-            updateRulesForUidLocked(uid);
-        }
+        // limit data usage for some internal system services
+        updateRulesForUidLocked(android.os.Process.MEDIA_UID);
+        updateRulesForUidLocked(android.os.Process.DRM_UID);
     }
 
     private void updateRulesForAppLocked(int appId) {
@@ -1688,7 +1677,19 @@ private void updateRulesForAppLocked(int appId) {
         }
     }
 
+    private static boolean isUidValidForRules(int uid) {
+        // allow rules on specific system services, and any apps
+        if (uid == android.os.Process.MEDIA_UID || uid == android.os.Process.DRM_UID
+                || UserId.isApp(uid)) {
+            return true;
+        }
+
+        return false;
+    }
+
     private void updateRulesForUidLocked(int uid) {
+        if (!isUidValidForRules(uid)) return;
+
         final int appId = UserId.getAppId(uid);
         final int appPolicy = getAppPolicy(appId);
         final boolean uidForeground = isUidForeground(uid);