netdev - Re: [Patch bpf-next v2 8/9] sock_map: update sock type checks for UDP

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Message-ID: <258c3229-1e60-20d9-e93f-9655ae969b6e@fb.com>
Date:   Tue, 2 Mar 2021 22:37:12 -0800
From:   Yonghong Song <yhs@...com>
To:     Cong Wang <xiyou.wangcong@...il.com>, <netdev@...r.kernel.org>
CC:     <bpf@...r.kernel.org>, <duanxiongchun@...edance.com>,
        <wangdongdong.6@...edance.com>, <jiang.wang@...edance.com>,
        Cong Wang <cong.wang@...edance.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: Re: [Patch bpf-next v2 8/9] sock_map: update sock type checks for UDP



On 3/1/21 6:37 PM, Cong Wang wrote:
> From: Cong Wang <cong.wang@...edance.com>
> 
> Now UDP supports sockmap and redirection, we can safely update
> the sock type checks for it accordingly.
> 
> Cc: John Fastabend <john.fastabend@...il.com>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: Jakub Sitnicki <jakub@...udflare.com>
> Cc: Lorenz Bauer <lmb@...udflare.com>
> Signed-off-by: Cong Wang <cong.wang@...edance.com>
> ---
>   net/core/sock_map.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/sock_map.c b/net/core/sock_map.c
> index 13d2af5bb81c..f7eee4b7b994 100644
> --- a/net/core/sock_map.c
> +++ b/net/core/sock_map.c
> @@ -549,7 +549,10 @@ static bool sk_is_udp(const struct sock *sk)
>   
>   static bool sock_map_redirect_allowed(const struct sock *sk)
>   {
> -	return sk_is_tcp(sk) && sk->sk_state != TCP_LISTEN;
> +	if (sk_is_tcp(sk))
> +		return sk->sk_state != TCP_LISTEN;
> +	else
> +		return sk->sk_state == TCP_ESTABLISHED;

Not a networking expert, a dump question. Here we tested
whether sk_is_tcp(sk) or not, if not we compare
sk->sk_state == TCP_ESTABLISHED, could this be
always false? Mostly I missed something, some comments
here will be good.

>   }
>   
>   static bool sock_map_sk_is_suitable(const struct sock *sk)
>