[PATCH net-next v20 14/25] ovpn: add support for MSG_NOSIGNAL in tcp_sendmsg

[Antonio Quartulli]

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 <eduma...@google.com>
Cc: Paolo Abeni <pab...@redhat.com>
Signed-off-by: Antonio Quartulli <anto...@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 
2d343bce477156a9f60ce92d18c815b7c832d2af..10cb0493290c9c4b90fb2734bcc208853d77dfd3
 100644
--- a/drivers/net/ovpn/tcp.c
+++ b/drivers/net/ovpn/tcp.c
@@ -215,6 +215,7 @@ 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;
@@ -225,9 +226,11 @@ 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;
@@ -370,7 +373,7 @@ 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;
        }
@@ -403,6 +406,7 @@ 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