linux-kernel - Re: [PATCH net-next v4 2/3] vsock: Move lingering logic to af

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <hcme242wm3h33zvbo6g6xinhbsjkeaawhsjjutxrhkjoh6xhin@gm5yvzv4ao7k>
Date: Tue, 6 May 2025 11:53:51 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Michal Luczaj <mhal@...x.co>
Cc: "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez <eperezma@...hat.com>, 
	Stefan Hajnoczi <stefanha@...hat.com>, virtualization@...ts.linux.dev, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH net-next v4 2/3] vsock: Move lingering logic to af_vsock
 core

On Thu, May 01, 2025 at 10:05:23AM +0200, Michal Luczaj wrote:
>Lingering should be transport-independent in the long run. In preparation
>for supporting other transports, as well the linger on shutdown(), move
>code to core.
>
>Generalize by querying vsock_transport::unsent_bytes(), guard against the
>callback being unimplemented. Do not pass sk_lingertime explicitly. Pull
>SOCK_LINGER check into vsock_linger().
>
>Flatten the function. Remove the nested block by inverting the condition:
>return early on !timeout.
>
>Suggested-by: Stefano Garzarella <sgarzare@...hat.com>
>Signed-off-by: Michal Luczaj <mhal@...x.co>
>---
> include/net/af_vsock.h                  |  1 +
> net/vmw_vsock/af_vsock.c                | 30 ++++++++++++++++++++++++++++++
> net/vmw_vsock/virtio_transport_common.c | 23 ++---------------------
> 3 files changed, 33 insertions(+), 21 deletions(-)
>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index 9e85424c834353d016a527070dd62e15ff3bfce1..d56e6e135158939087d060dfcf65d3fdaea53bf3 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -221,6 +221,7 @@ void vsock_for_each_connected_socket(struct vsock_transport *transport,
> 				     void (*fn)(struct sock *sk));
> int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock 
> *psk);
> bool vsock_find_cid(unsigned int cid);
>+void vsock_linger(struct sock *sk);
>
> /**** TAP ****/
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index fc6afbc8d6806a4d98c66abc3af4bd139c583b08..a31ad6b141cd38d1806df4b5d417924bb8607e32 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1013,6 +1013,36 @@ static int vsock_getname(struct socket *sock,
> 	return err;
> }
>
>+void vsock_linger(struct sock *sk)
>+{
>+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
>+	ssize_t (*unsent)(struct vsock_sock *vsk);
>+	struct vsock_sock *vsk = vsock_sk(sk);
>+	long timeout;
>+
>+	if (!sock_flag(sk, SOCK_LINGER))
>+		return;
>+
>+	timeout = sk->sk_lingertime;
>+	if (!timeout)
>+		return;
>+
>+	/* unsent_bytes() may be unimplemented. */

This comment IMO should be enriched, as it is now it doesn't add much to 
the code. I'm thinking on something like this:
     Transports must implement `unsent_bytes` if they want to support
     SOCK_LINGER through `vsock_linger()` since we use it to check when
     the socket can be closed.

The rest LGTM!

Thanks,
Stefano

>+	unsent = vsk->transport->unsent_bytes;
>+	if (!unsent)
>+		return;
>+
>+	add_wait_queue(sk_sleep(sk), &wait);
>+
>+	do {
>+		if (sk_wait_event(sk, &timeout, unsent(vsk) == 0, &wait))
>+			break;
>+	} while (!signal_pending(current) && timeout);
>+
>+	remove_wait_queue(sk_sleep(sk), &wait);
>+}
>+EXPORT_SYMBOL_GPL(vsock_linger);
>+
> static int vsock_shutdown(struct socket *sock, int mode)
> {
> 	int err;
>diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>index 
>045ac53f69735e1979162aea8c9ab5961407640c..aa308f285bf1bcf4c689407033de854c6f85a639 
>100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -1192,25 +1192,6 @@ static void virtio_transport_remove_sock(struct vsock_sock *vsk)
> 	vsock_remove_sock(vsk);
> }
>
>-static void virtio_transport_wait_close(struct sock *sk, long timeout)
>-{
>-	if (timeout) {
>-		DEFINE_WAIT_FUNC(wait, woken_wake_function);
>-		struct vsock_sock *vsk = vsock_sk(sk);
>-
>-		add_wait_queue(sk_sleep(sk), &wait);
>-
>-		do {
>-			if (sk_wait_event(sk, &timeout,
>-					  virtio_transport_unsent_bytes(vsk) == 0,
>-					  &wait))
>-				break;
>-		} while (!signal_pending(current) && timeout);
>-
>-		remove_wait_queue(sk_sleep(sk), &wait);
>-	}
>-}
>-
> static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
> 					       bool cancel_timeout)
> {
>@@ -1280,8 +1261,8 @@ static bool virtio_transport_close(struct vsock_sock *vsk)
> 	if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
> 		(void)virtio_transport_shutdown(vsk, SHUTDOWN_MASK);
>
>-	if (sock_flag(sk, SOCK_LINGER) && !(current->flags & PF_EXITING))
>-		virtio_transport_wait_close(sk, sk->sk_lingertime);
>+	if (!(current->flags & PF_EXITING))
>+		vsock_linger(sk);
>
> 	if (sock_flag(sk, SOCK_DONE)) {
> 		return true;
>
>-- 
>2.49.0
>