[PATCH net-next v18 14/25] ovpn: add support for MSG_NOSIGNAL in tcp_sendmsg

Antonio Quartulli
2025-01-13T09:31:23Z

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 fd19cc3081227e01c4c1ef25155de614b2dc2795..67c6e1e4a79041198f554d7c534bc2373ca96033 100644
--- a/drivers/net/ovpn/skb.h
+++ b/drivers/net/ovpn/skb.h
@@ -24,6 +24,7 @@ struct ovpn_cb {
struct aead_request *req;
struct scatterlist *sg;
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 f42b449b24d04ac247576d9de2c0513683e0072c..9776d87acc4742661423cd1824ac12b385889a97 100644
--- a/drivers/net/ovpn/tcp.c
+++ b/drivers/net/ovpn/tcp.c
@@ -217,6 +217,7 @@ void ovpn_tcp_socket_detach(struct ovpn_socket *ovpn_sock)
static void ovpn_tcp_send_sock(struct ovpn_peer *peer)
{
struct sk_buff *skb = peer->tcp.out_msg.skb;
+ int ret, flags;

if (!skb)
return;
@@ -227,9 +228,11 @@ static void ovpn_tcp_send_sock(struct ovpn_peer *peer)
peer->tcp.tx_in_progress = true;

do {
- int ret = skb_send_sock_locked(peer->sock->sock->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(peer->sock->sock->sk, skb,
+ peer->tcp.out_msg.offset,
+ peer->tcp.out_msg.len,
+ flags);
if (unlikely(ret < 0)) {
if (ret == -EAGAIN)
goto out;
@@ -369,7 +372,7 @@ static int ovpn_tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)

lock_sock(peer->sock->sock->sk);

- if (msg->msg_flags & ~MSG_DONTWAIT) {
+ if (msg->msg_flags & ~(MSG_DONTWAIT | MSG_NOSIGNAL)) {
ret = -EOPNOTSUPP;
goto peer_free;
}
@@ -402,6 +405,7 @@ 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(sock->peer, skb);
ret = size;
peer_free:

--
2.45.2