[PATCH v21 13/24] ovpn: add support for MSG_NOSIGNAL in tcp_sendmsg

[Antonio Quartulli <antonio@openvpn.net>]

Userspace may want to pass the MSG_NOSIGNAL flag to
tcp_sendmsg() in order to avoid generating a SIGPIPE.

To pass this flag down the TCP stack a new skb sending API
accepting a flags argument is introduced.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 drivers/net/ovpn/skb.h |  1 +
 drivers/net/ovpn/tcp.c | 12 ++++++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ovpn/skb.h b/drivers/net/ovpn/skb.h
index bd3cbcfc770d2c28d234fcdd081b4d02e6496ea0..64430880f1dae33a41f698d713cf151be5b38577 100644
--- a/drivers/net/ovpn/skb.h
+++ b/drivers/net/ovpn/skb.h
@@ -25,6 +25,7 @@ struct ovpn_cb {
 	struct scatterlist *sg;
 	u8 *iv;
 	unsigned int payload_offset;
+	bool nosignal;
 };
 
 static inline struct ovpn_cb *ovpn_skb_cb(struct sk_buff *skb)
diff --git a/drivers/net/ovpn/tcp.c b/drivers/net/ovpn/tcp.c
index a5bfd06bc9499b6886b42e039095bb8ce93994fb..e05c9ba0e0f5f74bd99fc0ed918fb93cd1f3d494 100644
--- a/drivers/net/ovpn/tcp.c
+++ b/drivers/net/ovpn/tcp.c
@@ -220,6 +220,7 @@ void ovpn_tcp_socket_wait_finish(struct ovpn_socket *sock)
 static void ovpn_tcp_send_sock(struct ovpn_peer *peer, struct sock *sk)
 {
 	struct sk_buff *skb = peer->tcp.out_msg.skb;
+	int ret, flags;
 
 	if (!skb)
 		return;
@@ -230,9 +231,11 @@ static void ovpn_tcp_send_sock(struct ovpn_peer *peer, struct sock *sk)
 	peer->tcp.tx_in_progress = true;
 
 	do {
-		int ret = skb_send_sock_locked(sk, skb,
-					       peer->tcp.out_msg.offset,
-					       peer->tcp.out_msg.len);
+		flags = ovpn_skb_cb(skb)->nosignal ? MSG_NOSIGNAL : 0;
+		ret = skb_send_sock_locked_with_flags(sk, skb,
+						      peer->tcp.out_msg.offset,
+						      peer->tcp.out_msg.len,
+						      flags);
 		if (unlikely(ret < 0)) {
 			if (ret == -EAGAIN)
 				goto out;
@@ -380,7 +383,7 @@ static int ovpn_tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	rcu_read_unlock();
 	peer = sock->peer;
 
-	if (msg->msg_flags & ~MSG_DONTWAIT) {
+	if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_NOSIGNAL)) {
 		ret = -EOPNOTSUPP;
 		goto peer_free;
 	}
@@ -413,6 +416,7 @@ static int ovpn_tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 		goto peer_free;
 	}
 
+	ovpn_skb_cb(skb)->nosignal = msg->msg_flags & MSG_NOSIGNAL;
 	ovpn_tcp_send_sock_skb(peer, sk, skb);
 	ret = size;
 peer_free:

-- 
2.45.3