diff mbox series

[net-next,3/5] mptcp: ignore unsupported msg flags

Message ID 20210423181709.330233-4-mathew.j.martineau@linux.intel.com
State New
Headers show
Series [net-next,1/5] mptcp: implement dummy MSG_ERRQUEUE support | expand

Commit Message

Mat Martineau April 23, 2021, 6:17 p.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

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: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index ae08c563c712..a996dd5bb0c2 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -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;