Commit 987858e5 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

mptcp: ignore unsupported msg flags 

Currently mptcp_sendmsg() fails with EOPNOTSUPP if the
user-space provides some unsupported flag. That is unexpected
and may foul existing applications migrated to MPTCP, which
expect a different behavior.

Change the mentioned function to silently ignore the unsupported
flags except MSG_FASTOPEN. This is the only flags currently not
supported by MPTCP with user-space visible side-effects.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/162


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d976092c

net/mptcp/protocol.c

+5 −4
Original line number Diff line number Diff line
@@ -1614,9 +1614,13 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) 
	int ret = 0;

	long timeo;



	if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL))

	/* we don't support FASTOPEN yet */

	if (msg->msg_flags & MSG_FASTOPEN)

		return -EOPNOTSUPP;



	/* silently ignore everything else */

	msg->msg_flags &= MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL;



	mptcp_lock_sock(sk, __mptcp_wmem_reserve(sk, min_t(size_t, 1 << 20, len)));



	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
@@ -1951,9 +1955,6 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, 
	if (unlikely(flags & MSG_ERRQUEUE))

		return inet_recv_error(sk, msg, len, addr_len);



	if (msg->msg_flags & ~(MSG_WAITALL | MSG_DONTWAIT))

		return -EOPNOTSUPP;



	mptcp_lock_sock(sk, __mptcp_splice_receive_queue(sk));

	if (unlikely(sk->sk_state == TCP_LISTEN)) {

		copied = -ENOTCONN;