commit d7b63f8f93edb6977f097e3b63fd91059f92717a
author Hungming Chen <nuccachen@google.com> Sat Jan 22 22:15:56 2022 +0800
committer Hungming Chen <nuccachen@google.com> Tue Jan 25 20:32:11 2022 +0800
tree 293e50dd013f91ceca8f65d539a16fde1d155c92
parent 9d11ddfd5c3872b7ced68ecdef76af8fc0183981

[CLATJ#23] Close the file descriptor manually

ParcelFileDescriptor rely on garbage collection to close handler.
When there is any error during starting clat or quick on/off
IPv6 only network, the file descriptor may not be able to be closed
before next clatStart is called. This may be problematic. For
example, the same v4- tun interface has not closed yet and clatStart
has been called again.

Test: connect/disconnect to IPv6 only network and ping 8.8.8.8
      repeat 10 times
Change-Id: I8e1c66206dc221827a039213ecc86d5cbd777dff

service/src/com/android/server/connectivity/ClatCoordinator.java

diff --git a/service/src/com/android/server/connectivity/ClatCoordinator.java b/service/src/com/android/server/connectivity/ClatCoordinator.java
index 9cdc086..7616457 100644
--- a/service/src/com/android/server/connectivity/ClatCoordinator.java
+++ b/service/src/com/android/server/connectivity/ClatCoordinator.java
@@ -257,6 +257,7 @@
         try {
             mNetd.interfaceSetEnableIPv6(tunIface, false /* enabled */);
         } catch (RemoteException | ServiceSpecificException e) {
+            tunFd.close();
             Log.e(TAG, "Disable IPv6 on " + tunIface + " failed: " + e);
         }
 
@@ -273,6 +274,7 @@
         try {
             mNetd.interfaceSetMtu(tunIface, mtu);
         } catch (RemoteException | ServiceSpecificException e) {
+            tunFd.close();
             throw new IOException("Set MTU " + mtu + " on " + tunIface + " failed: " + e);
         }
         final InterfaceConfigurationParcel ifConfig = new InterfaceConfigurationParcel();
@@ -284,6 +286,7 @@
         try {
             mNetd.interfaceSetCfg(ifConfig);
         } catch (RemoteException | ServiceSpecificException e) {
+            tunFd.close();
             throw new IOException("Setting IPv4 address to " + ifConfig.ipv4Addr + "/"
                     + ifConfig.prefixLength + " failed on " + ifConfig.ifName + ": " + e);
         }
@@ -293,11 +296,12 @@
         final ParcelFileDescriptor readSock6;
         try {
             // Use a JNI call to get native file descriptor instead of Os.socket() because we would
-            // like to use ParcelFileDescriptor to close file descriptor automatically. But ctor
+            // like to use ParcelFileDescriptor to manage file descriptor. But ctor
             // ParcelFileDescriptor(FileDescriptor fd) is a @hide function. Need to use native file
             // descriptor to initialize ParcelFileDescriptor object instead.
             readSock6 = mDeps.adoptFd(mDeps.openPacketSocket());
         } catch (IOException e) {
+            tunFd.close();
             throw new IOException("Open packet socket failed: " + e);
         }
 
@@ -308,11 +312,16 @@
             // reason why we use jniOpenPacketSocket6().
             writeSock6 = mDeps.adoptFd(mDeps.openRawSocket6(fwmark));
         } catch (IOException e) {
+            tunFd.close();
+            readSock6.close();
             throw new IOException("Open raw socket failed: " + e);
         }
 
         final int ifaceIndex = mDeps.getInterfaceIndex(iface);
         if (ifaceIndex == INVALID_IFINDEX) {
+            tunFd.close();
+            readSock6.close();
+            writeSock6.close();
             throw new IOException("Fail to get interface index for interface " + iface);
         }
 
@@ -320,6 +329,9 @@
         try {
             mDeps.addAnycastSetsockopt(writeSock6.getFileDescriptor(), v6, ifaceIndex);
         } catch (IOException e) {
+            tunFd.close();
+            readSock6.close();
+            writeSock6.close();
             throw new IOException("add anycast sockopt failed: " + e);
         }
 
@@ -327,6 +339,9 @@
         try {
             mDeps.configurePacketSocket(readSock6.getFileDescriptor(), v6, ifaceIndex);
         } catch (IOException e) {
+            tunFd.close();
+            readSock6.close();
+            writeSock6.close();
             throw new IOException("configure packet socket failed: " + e);
         }
 
@@ -340,6 +355,10 @@
             mXlatLocalAddress6 = v6;
         } catch (IOException e) {
             throw new IOException("Error start clatd on " + iface + ": " + e);
+        } finally {
+            tunFd.close();
+            readSock6.close();
+            writeSock6.close();
         }
 
         return v6;