Commit 1de00964 authored Dec 17, 2018 by Nick Kralevich

NativeHandle.java: dup() with O_CLOEXEC

Don't use Os.dup(), as it creates file handles which leak across exec()
boundaries. Instead, use fcntl(F_DUPFD_CLOEXEC);

O_CLOEXEC is essential for ensuring that file descriptors do not leak
across an exec() boundary. Setting O_CLOEXEC ensures that file
descriptors can't linger around unnecessarily in an exec()ed process
which doesn't use them, making more efficient use of resources.
Additionally, O_CLOEXEC is important in ensuring that untrusted
exec()ed code cannot take advantage of leaked file descriptors.

Test: Android compiles and boots
Bug: 120983106
Change-Id: I99a66834cc6b9bb25e1b4daf75384ec6a91ae9e2

parent bc292422

core/java/android/os/NativeHandle.java

+6 −1

Original line number	Diff line number	Diff line
		@@ -16,6 +16,8 @@

		package android.os;

		import static android.system.OsConstants.F_DUPFD_CLOEXEC;

		import android.annotation.NonNull;
		import android.annotation.SystemApi;
		import android.system.ErrnoException;
		@@ -108,7 +110,10 @@ public final class NativeHandle implements Closeable {
		FileDescriptor[] fds = new FileDescriptor[mFds.length];
		try {
		for (int i = 0; i < mFds.length; i++) {
		fds[i] = Os.dup(mFds[i]);
		FileDescriptor newFd = new FileDescriptor();
		int fdint = Os.fcntlInt(mFds[i], F_DUPFD_CLOEXEC, 0);
		newFd.setInt$(fdint);
		fds[i] = newFd;
		}
		} catch (ErrnoException e) {
		e.rethrowAsIOException();