From: Antonio Quartulli <antonio@openvpn.net>
Date: Tue, 15 Apr 2025 11:17:30 +0000 (+0200)
Subject: ovpn: add support for MSG_NOSIGNAL in tcp_sendmsg
X-Git-Tag: v6.16-rc1~132^2~277^2~10
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=36bb1d713a15e361e74249b75a9fd26d64967a7b;p=thirdparty%2Flinux.git

ovpn: add support for MSG_NOSIGNAL in tcp_sendmsg

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>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-13-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---

diff --git a/drivers/net/ovpn/skb.h b/drivers/net/ovpn/skb.h
index bd3cbcfc770d2..64430880f1dae 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 588ff6b044010..7c42d84987ad3 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: