linux-kernel - Re: It's back! (Re: [REGRESSION] NFS is creating a hidden port (left over from xs

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Date:   Tue, 6 Feb 2018 10:20:22 +0100
From:   Daniel Reichelt <hacking@...htgeist.net>
To:     Trond Myklebust <trondmy@...marydata.com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>
Subject: Re: It's back! (Re: [REGRESSION] NFS is creating a hidden port (left
 over from xs_bind() ))

On 02/06/2018 01:24 AM, Trond Myklebust wrote:
> Does the following fix the issue?
> 
> 8<-----------------------------------------------
> From 9b30889c548a4d45bfe6226e58de32504c1d682f Mon Sep 17 00:00:00 2001
> From: Trond Myklebust <trond.myklebust@...marydata.com>
> Date: Mon, 5 Feb 2018 10:20:06 -0500
> Subject: [PATCH] SUNRPC: Ensure we always close the socket after a connection
>  shuts down
> 
> Ensure that we release the TCP socket once it is in the TCP_CLOSE or
> TCP_TIME_WAIT state (and only then) so that we don't confuse rkhunter
> and its ilk.
> 
> Signed-off-by: Trond Myklebust <trond.myklebust@...marydata.com>
> ---
>  net/sunrpc/xprtsock.c | 23 ++++++++++-------------
>  1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 18803021f242..5d0108172ed3 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -807,13 +807,6 @@ static void xs_sock_reset_connection_flags(struct rpc_xprt *xprt)
>  	smp_mb__after_atomic();
>  }
>  
> -static void xs_sock_mark_closed(struct rpc_xprt *xprt)
> -{
> -	xs_sock_reset_connection_flags(xprt);
> -	/* Mark transport as closed and wake up all pending tasks */
> -	xprt_disconnect_done(xprt);
> -}
> -
>  /**
>   * xs_error_report - callback to handle TCP socket state errors
>   * @sk: socket
> @@ -833,9 +826,6 @@ static void xs_error_report(struct sock *sk)
>  	err = -sk->sk_err;
>  	if (err == 0)
>  		goto out;
> -	/* Is this a reset event? */
> -	if (sk->sk_state == TCP_CLOSE)
> -		xs_sock_mark_closed(xprt);
>  	dprintk("RPC:       xs_error_report client %p, error=%d...\n",
>  			xprt, -err);
>  	trace_rpc_socket_error(xprt, sk->sk_socket, err);
> @@ -1655,9 +1645,11 @@ static void xs_tcp_state_change(struct sock *sk)
>  		if (test_and_clear_bit(XPRT_SOCK_CONNECTING,
>  					&transport->sock_state))
>  			xprt_clear_connecting(xprt);
> +		clear_bit(XPRT_CLOSING, &xprt->state);
>  		if (sk->sk_err)
>  			xprt_wake_pending_tasks(xprt, -sk->sk_err);
> -		xs_sock_mark_closed(xprt);
> +		/* Trigger the socket release */
> +		xs_tcp_force_close(xprt);
>  	}
>   out:
>  	read_unlock_bh(&sk->sk_callback_lock);
> @@ -2265,14 +2257,19 @@ static void xs_tcp_shutdown(struct rpc_xprt *xprt)
>  {
>  	struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
>  	struct socket *sock = transport->sock;
> +	int skst = transport->inet ? transport->inet->sk_state : TCP_CLOSE;
>  
>  	if (sock == NULL)
>  		return;
> -	if (xprt_connected(xprt)) {
> +	switch (skst) {
> +	default:
>  		kernel_sock_shutdown(sock, SHUT_RDWR);
>  		trace_rpc_socket_shutdown(xprt, sock);
> -	} else
> +		break;
> +	case TCP_CLOSE:
> +	case TCP_TIME_WAIT:
>  		xs_reset_transport(transport);
> +	}
>  }
>  
>  static void xs_tcp_set_socket_timeouts(struct rpc_xprt *xprt,
> 


Previously, I've seen hidden ports within 5-6 minutes after re-starting
the nfsd and re-mounting nfs-exports on clients.

With this patch applied, I don't see any hidden ports after 15mins. I
guess it's a valid fix.


Thank you!

Daniel



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