netdev - Re: [PATCH net-next v9 03/10] tcp: use drop reasons in cookie check for ipv4

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Message-ID: <20240223192237.4781-1-kuniyu@amazon.com>
Date: Fri, 23 Feb 2024 11:22:37 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <kerneljasonxing@...il.com>
CC: <davem@...emloft.net>, <dsahern@...nel.org>, <edumazet@...gle.com>,
	<kernelxing@...cent.com>, <kuba@...nel.org>, <kuniyu@...zon.com>,
	<netdev@...r.kernel.org>, <pabeni@...hat.com>
Subject: Re: [PATCH net-next v9 03/10] tcp: use drop reasons in cookie check for ipv4

From: Jason Xing <kerneljasonxing@...il.com>
Date: Fri, 23 Feb 2024 18:28:44 +0800
> From: Jason Xing <kernelxing@...cent.com>
> 
> Now it's time to use the prepared definitions to refine this part.
> Four reasons used might enough for now, I think.
> 
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> Reviewed-by: Eric Dumazet <edumazet@...gle.com>
> Reviewed-by: David Ahern <dsahern@...nel.org>

Reviewed-by: Kuniyuki Iwashima <kuniyu@...zon.com>


> --
> v9
> Link: https://lore.kernel.org/netdev/c5640fc4-16dc-4058-97c6-bd84bae4fda1@kernel.org/
> Link: https://lore.kernel.org/netdev/CANn89iLOxJxmOCH1LxXf-YwRBzKXcjPRmgQeQ6A3bKRmW8=ksg@mail.gmail.com/
> 1. add reviewed-by tag (David)
> 2. add reviewed-by tag (Eric)
> 
> v8
> Link: https://lore.kernel.org/netdev/CANn89iL-FH6jzoxhyKSMioj-zdBsHqNpR7YTGz8ytM=FZSGrug@mail.gmail.com/
> 1. refine the codes (Eric)
> 
> v6:
> Link: https://lore.kernel.org/netdev/20240215210922.19969-1-kuniyu@amazon.com/
> 1. Not use NOMEM because of MPTCP (Kuniyuki). I chose to use NO_SOCKET as
> an indicator which can be used as three kinds of cases to tell people that we're
> unable to get a valid one. It's a relatively general reason like what we did
> to TCP_FLAGS.
> Any better ideas/suggestions are welcome :)
> 
> v5:
> Link: https://lore.kernel.org/netdev/CANn89i+iELpsoea6+C-08m6+=JkneEEM=nAj-28eNtcOCkwQjw@mail.gmail.com/
> Link: https://lore.kernel.org/netdev/632c6fd4-e060-4b8e-a80e-5d545a6c6b6c@kernel.org/
> 1. Use SKB_DROP_REASON_IP_OUTNOROUTES instead of introducing a new one (Eric, David)
> 2. Reuse SKB_DROP_REASON_NOMEM to handle failure of request socket allocation (Eric)
> 3. Reuse NO_SOCKET instead of introducing COOKIE_NOCHILD
> ---
>  net/ipv4/syncookies.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
> index 38f331da6677..7972ad3d7c73 100644
> --- a/net/ipv4/syncookies.c
> +++ b/net/ipv4/syncookies.c
> @@ -421,8 +421,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
>  		if (IS_ERR(req))
>  			goto out;
>  	}
> -	if (!req)
> +	if (!req) {
> +		SKB_DR_SET(reason, NO_SOCKET);
>  		goto out_drop;
> +	}
>  
>  	ireq = inet_rsk(req);
>  
> @@ -434,8 +436,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
>  	 */
>  	RCU_INIT_POINTER(ireq->ireq_opt, tcp_v4_save_options(net, skb));
>  
> -	if (security_inet_conn_request(sk, skb, req))
> +	if (security_inet_conn_request(sk, skb, req)) {
> +		SKB_DR_SET(reason, SECURITY_HOOK);
>  		goto out_free;
> +	}
>  
>  	tcp_ao_syncookie(sk, skb, req, AF_INET);
>  
> @@ -452,8 +456,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
>  			   ireq->ir_loc_addr, th->source, th->dest, sk->sk_uid);
>  	security_req_classify_flow(req, flowi4_to_flowi_common(&fl4));
>  	rt = ip_route_output_key(net, &fl4);
> -	if (IS_ERR(rt))
> +	if (IS_ERR(rt)) {
> +		SKB_DR_SET(reason, IP_OUTNOROUTES);
>  		goto out_free;
> +	}
>  
>  	/* Try to redo what tcp_v4_send_synack did. */
>  	req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
> @@ -476,10 +482,11 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
>  	/* ip_queue_xmit() depends on our flow being setup
>  	 * Normal sockets get it right from inet_csk_route_child_sock()
>  	 */
> -	if (ret)
> -		inet_sk(ret)->cork.fl.u.ip4 = fl4;
> -	else
> +	if (!ret) {
> +		SKB_DR_SET(reason, NO_SOCKET);
>  		goto out_drop;
> +	}
> +	inet_sk(ret)->cork.fl.u.ip4 = fl4;
>  out:
>  	return ret;
>  out_free:
> -- 
> 2.37.3