netdev - Re: [PATCH net-next v9 05/10] tcp: use drop reasons in cookie check for ipv6

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Message-ID: <20240223192851.6413-1-kuniyu@amazon.com>
Date: Fri, 23 Feb 2024 11:28:51 -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 05/10] tcp: use drop reasons in cookie check for ipv6

From: Jason Xing <kerneljasonxing@...il.com>
Date: Fri, 23 Feb 2024 18:28:46 +0800
> From: Jason Xing <kernelxing@...cent.com>
> 
> Like what I did to ipv4 mode, refine this part: adding more drop
> reasons for better tracing.
> 
> 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/
> 1. add reviewed-by tag (David)
> 
> v8
> Link: https://lore.kernel.org/netdev/CANn89i+b+bYqX0aVv9KtSm=nLmEQznamZmqaOzfqtJm_ux9JBw@mail.gmail.com/
> 1. add reviewed-by tag (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.
> 
> v5:
> Link: https://lore.kernel.org/netdev/CANn89i+iELpsoea6+C-08m6+=JkneEEM=nAj-28eNtcOCkwQjw@mail.gmail.com/
> 1. Reuse SKB_DROP_REASON_NOMEM to handle failure of request socket allocation (Eric)
> 2. Reuse NO_SOCKET instead of introducing COOKIE_NOCHILD
> 3. Reuse IP_OUTNOROUTES instead of INVALID_DST (Eric)
> ---
>  net/ipv6/syncookies.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
> index ea0d9954a29f..8bad0a44a0a6 100644
> --- a/net/ipv6/syncookies.c
> +++ b/net/ipv6/syncookies.c
> @@ -190,16 +190,20 @@ struct sock *cookie_v6_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);
>  
>  	ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
>  	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
>  
> -	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;
> +	}
>  
>  	if (ipv6_opt_accepted(sk, skb, &TCP_SKB_CB(skb)->header.h6) ||
>  	    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
> @@ -236,8 +240,10 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
>  		security_req_classify_flow(req, flowi6_to_flowi_common(&fl6));
>  
>  		dst = ip6_dst_lookup_flow(net, sk, &fl6, final_p);
> -		if (IS_ERR(dst))
> +		if (IS_ERR(dst)) {
> +			SKB_DR_SET(reason, IP_OUTNOROUTES);
>  			goto out_free;
> +		}
>  	}
>  
>  	req->rsk_window_clamp = tp->window_clamp ? :dst_metric(dst, RTAX_WINDOW);
> @@ -257,8 +263,10 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
>  	ireq->ecn_ok &= cookie_ecn_ok(net, dst);
>  
>  	ret = tcp_get_cookie_sock(sk, skb, req, dst);
> -	if (!ret)
> +	if (!ret) {
> +		SKB_DR_SET(reason, NO_SOCKET);
>  		goto out_drop;
> +	}
>  out:
>  	return ret;
>  out_free:
> -- 
> 2.37.3