Subject: [PATCH net-next v8 08/10] tcp: add dropreasons in tcp_rcv_state_process()

From: Jason Xing <[email-masked]>
Date: Thu, 22 Feb 2024 19:30:01 +0800

From: Jason Xing <[email-masked]>

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 <[email-masked]>
Reviewed-by: Eric Dumazet <[email-masked]>
--
v8
Link: https://lore.kernel.org/netdev/CANn89iJJ9XTVeC=[email-masked]/
1. add reviewed-by tag (Eric)

v5:
Link: https://lore.kernel.org/netdev/[email-masked]/
1. Use new name (TCP_ABORT_ON_DATA) for readability (David)
---
 include/net/tcp.h    |  2 +-
 net/ipv4/tcp_input.c | 20 +++++++++++++-------
 2 files changed, 14 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..b257da06c0c7 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 +6705,13 @@ 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;
+			else
+				return -reason;
+		}
 		/* accept old ack during closing */
 		if ((int)reason < 0) {
 			tcp_send_challenge_ack(sk);
@@ -6781,7 +6787,7 @@ 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 +6796,7 @@ 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 +6861,7 @@ 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