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mptcp: ignore unsupported msg flags

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2021-04-23 11:17:07 -07:00 committed by David S. Miller
parent d976092ce1
commit 987858e5d0
1 changed files with 5 additions and 4 deletions
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9
net/mptcp/protocol.c
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@ -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;