Re: [PATCH net-next v9 08/10] tcp: add dropreasons in tcp_rcv_state_process()

[Kuniyuki Iwashima <kuniyu@amazon.com>]

From: Jason Xing <kerneljasonxing@gmail.com>
Date: Fri, 23 Feb 2024 18:28:49 +0800
> From: Jason Xing <kernelxing@tencent.com>
> 
> In this patch, I equipped this function with more dropreasons, but
> it still doesn't work yet, which I will do later.
> 
> Signed-off-by: Jason Xing <kernelxing@tencent.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> Reviewed-by: David Ahern <dsahern@kernel.org>

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


> --
> v9
> Link: https://lore.kernel.org/netdev/CAL+tcoCbsbM=HyXRqs2+QVrY8FSKmqYC47m87Axiyk1wk4omwQ@mail.gmail.com/
> Link: https://lore.kernel.org/netdev/c5640fc4-16dc-4058-97c6-bd84bae4fda1@kernel.org/
> 1. nit: remove unnecessary else (David)
> 2. add reviewed-by tag (David)
> 
> v8
> Link: https://lore.kernel.org/netdev/CANn89iJJ9XTVeC=qbSNUnOhQMAsfBfouc9qUJY7MxgQtYGmB3Q@mail.gmail.com/
> 1. add reviewed-by tag (Eric)
> 
> v5:
> Link: https://lore.kernel.org/netdev/3a495358-4c47-4a9f-b116-5f9c8b44e5ab@kernel.org/
> 1. Use new name (TCP_ABORT_ON_DATA) for readability (David)
> ---
>  include/net/tcp.h    |  2 +-
>  net/ipv4/tcp_input.c | 19 ++++++++++++-------
>  2 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 58e65af74ad1..e5af9a5b411b 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -348,7 +348,7 @@ void tcp_wfree(struct sk_buff *skb);
>  void tcp_write_timer_handler(struct sock *sk);
>  void tcp_delack_timer_handler(struct sock *sk);
>  int tcp_ioctl(struct sock *sk, int cmd, int *karg);
> -int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
> +enum skb_drop_reason tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
>  void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
>  void tcp_rcv_space_adjust(struct sock *sk);
>  int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 83308cca1610..5d874817a78d 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -6619,7 +6619,8 @@ static void tcp_rcv_synrecv_state_fastopen(struct sock *sk)
>   *	address independent.
>   */
>  
> -int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
> +enum skb_drop_reason
> +tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
>  {
>  	struct tcp_sock *tp = tcp_sk(sk);
>  	struct inet_connection_sock *icsk = inet_csk(sk);
> @@ -6635,7 +6636,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
>  
>  	case TCP_LISTEN:
>  		if (th->ack)
> -			return 1;
> +			return SKB_DROP_REASON_TCP_FLAGS;
>  
>  		if (th->rst) {
>  			SKB_DR_SET(reason, TCP_RESET);
> @@ -6704,8 +6705,12 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
>  				  FLAG_NO_CHALLENGE_ACK);
>  
>  	if ((int)reason <= 0) {
> -		if (sk->sk_state == TCP_SYN_RECV)
> -			return 1;	/* send one RST */
> +		if (sk->sk_state == TCP_SYN_RECV) {
> +			/* send one RST */
> +			if (!reason)
> +				return SKB_DROP_REASON_TCP_OLD_ACK;
> +			return -reason;
> +		}
>  		/* accept old ack during closing */
>  		if ((int)reason < 0) {
>  			tcp_send_challenge_ack(sk);
> @@ -6781,7 +6786,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
>  		if (READ_ONCE(tp->linger2) < 0) {
>  			tcp_done(sk);
>  			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
> -			return 1;
> +			return SKB_DROP_REASON_TCP_ABORT_ON_DATA;
>  		}
>  		if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
>  		    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
> @@ -6790,7 +6795,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
>  				tcp_fastopen_active_disable(sk);
>  			tcp_done(sk);
>  			NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
> -			return 1;
> +			return SKB_DROP_REASON_TCP_ABORT_ON_DATA;
>  		}
>  
>  		tmo = tcp_fin_time(sk);
> @@ -6855,7 +6860,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
>  			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
>  				NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
>  				tcp_reset(sk, skb);
> -				return 1;
> +				return SKB_DROP_REASON_TCP_ABORT_ON_DATA;
>  			}
>  		}
>  		fallthrough;
> -- 
> 2.37.3