netdev - Re: [PATCH net] vsock/bpf: Handle EINTR connect() racing against sockmap update

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: <wt72yg4zs5zqubpyrgccibuo5zpfwjlm5t2bnmfd4j3z2k5lio@3qqnuqs7loet>
Date: Fri, 7 Mar 2025 15:33:18 +0100
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>, 
	Bobby Eshleman <bobby.eshleman@...edance.com>, "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org, 
	bpf@...r.kernel.org
Subject: Re: [PATCH net] vsock/bpf: Handle EINTR connect() racing against
 sockmap update

On Fri, Mar 07, 2025 at 10:27:50AM +0100, Michal Luczaj wrote:
>Signal delivered during connect() may result in a disconnect of an already
>TCP_ESTABLISHED socket. Problem is that such established socket might have
>been placed in a sockmap before the connection was closed. We end up with a
>SS_UNCONNECTED vsock in a sockmap. And this, combined with the ability to
>reassign (unconnected) vsock's transport to NULL, breaks the sockmap
>contract. As manifested by WARN_ON_ONCE.
>
>Ensure the socket does not stay in sockmap.
>
>WARNING: CPU: 10 PID: 1310 at net/vmw_vsock/vsock_bpf.c:90 vsock_bpf_recvmsg+0xb4b/0xdf0
>CPU: 10 UID: 0 PID: 1310 Comm: a.out Tainted: G        W          6.14.0-rc4+
> sock_recvmsg+0x1b2/0x220
> __sys_recvfrom+0x190/0x270
> __x64_sys_recvfrom+0xdc/0x1b0
> do_syscall_64+0x93/0x1b0
> entry_SYSCALL_64_after_hwframe+0x76/0x7e
>
>Fixes: 634f1a7110b4 ("vsock: support sockmap")
>Signed-off-by: Michal Luczaj <mhal@...x.co>
>---
> net/vmw_vsock/af_vsock.c  | 10 +++++++++-
> net/vmw_vsock/vsock_bpf.c |  1 +
> 2 files changed, 10 insertions(+), 1 deletion(-)

I can't see this patch on the virtualization ML, are you using 
get_maintainer.pl?

$ ./scripts/get_maintainer.pl -f net/vmw_vsock/af_vsock.c
Stefano Garzarella <sgarzare@...hat.com> (maintainer:VM SOCKETS (AF_VSOCK))
"David S. Miller" <davem@...emloft.net> (maintainer:NETWORKING [GENERAL])
Eric Dumazet <edumazet@...gle.com> (maintainer:NETWORKING [GENERAL])
Jakub Kicinski <kuba@...nel.org> (maintainer:NETWORKING [GENERAL])
Paolo Abeni <pabeni@...hat.com> (maintainer:NETWORKING [GENERAL])
Simon Horman <horms@...nel.org> (reviewer:NETWORKING [GENERAL])
virtualization@...ts.linux.dev (open list:VM SOCKETS (AF_VSOCK))
netdev@...r.kernel.org (open list:VM SOCKETS (AF_VSOCK))
linux-kernel@...r.kernel.org (open list)

BTW the patch LGTM, thanks for the fix!

Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>

>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 7742a9ae0131310bba197830a241541b2cde6123..e5a6d1d413634f414370595c02bcd77664780d8e 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1581,7 +1581,15 @@ static int vsock_connect(struct socket *sock, struct sockaddr *addr,
>
> 		if (signal_pending(current)) {
> 			err = sock_intr_errno(timeout);
>-			sk->sk_state = sk->sk_state == TCP_ESTABLISHED ? TCP_CLOSING : TCP_CLOSE;
>+			if (sk->sk_state == TCP_ESTABLISHED) {
>+				/* Might have raced with a sockmap update. */
>+				if (sk->sk_prot->unhash)
>+					sk->sk_prot->unhash(sk);
>+
>+				sk->sk_state = TCP_CLOSING;
>+			} else {
>+				sk->sk_state = TCP_CLOSE;
>+			}
> 			sock->state = SS_UNCONNECTED;
> 			vsock_transport_cancel_pkt(vsk);
> 			vsock_remove_connected(vsk);
>diff --git a/net/vmw_vsock/vsock_bpf.c b/net/vmw_vsock/vsock_bpf.c
>index 07b96d56f3a577af71021b1b8132743554996c4f..c68fdaf09046b68254dac3ea70ffbe73dfa45cef 100644
>--- a/net/vmw_vsock/vsock_bpf.c
>+++ b/net/vmw_vsock/vsock_bpf.c
>@@ -127,6 +127,7 @@ static void vsock_bpf_rebuild_protos(struct proto *prot, const struct proto *bas
> {
> 	*prot        = *base;
> 	prot->close  = sock_map_close;
>+	prot->unhash = sock_map_unhash;
> 	prot->recvmsg = vsock_bpf_recvmsg;
> 	prot->sock_is_readable = sk_msg_is_readable;
> }
>
>---
>base-commit: b1455a45afcf789f98032ec93c16fea0facdec93
>change-id: 20250305-vsock-trans-signal-race-d62f7718d099
>
>Best regards,
>-- 
>Michal Luczaj <mhal@...x.co>
>