Subject: [PATCH net-next 4/5] tcp: handle timewait cases in rstreason logic

From: Jason Xing <[email-masked]>
Date: Thu, 9 May 2024 21:13:05 +0800

From: Jason Xing <[email-masked]>

There are two possible cases where TCP layer can send an RST. Since they
happen in the same place, I think using one independent reason is enough
to identify this special situation.

Signed-off-by: Jason Xing <[email-masked]>
---
 include/net/rstreason.h | 5 +++++
 net/ipv4/tcp_ipv4.c     | 2 +-
 net/ipv6/tcp_ipv6.c     | 2 +-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/net/rstreason.h b/include/net/rstreason.h
index 61855d4b27e2..62e869089da4 100644
--- a/include/net/rstreason.h
+++ b/include/net/rstreason.h
@@ -15,6 +15,7 @@
 	FN(TCP_FLAGS)			\
 	FN(TCP_OLD_ACK)			\
 	FN(TCP_ABORT_ON_DATA)		\
+	FN(TCP_TIMEWAIT_SOCKET)		\
 	FN(MPTCP_RST_EUNSPEC)		\
 	FN(MPTCP_RST_EMPTCP)		\
 	FN(MPTCP_RST_ERESOURCE)		\
@@ -69,6 +70,10 @@ enum sk_rst_reason {
 	 */
 	SK_RST_REASON_TCP_ABORT_ON_DATA,
 
+	/* Here start with the independent reasons */
+	/** @SK_RST_REASON_TCP_TIMEWAIT_SOCKET: happen on the timewait socket */
+	SK_RST_REASON_TCP_TIMEWAIT_SOCKET,
+
 	/* Copy from include/uapi/linux/mptcp.h.
 	 * These reset fields will not be changed since they adhere to
 	 * RFC 8684. So do not touch them. I'm going to list each definition
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0427deca3e0e..d35cdb77d7b5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2421,7 +2421,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		tcp_v4_timewait_ack(sk, skb);
 		break;
 	case TCP_TW_RST:
-		tcp_v4_send_reset(sk, skb, sk_rst_convert_drop_reason(drop_reason));
+		tcp_v4_send_reset(sk, skb, SK_RST_REASON_TCP_TIMEWAIT_SOCKET);
 		inet_twsk_deschedule_put(inet_twsk(sk));
 		goto discard_it;
 	case TCP_TW_SUCCESS:;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 37201c4fb393..bee26b961835 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1999,7 +1999,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		tcp_v6_timewait_ack(sk, skb);
 		break;
 	case TCP_TW_RST:
-		tcp_v6_send_reset(sk, skb, sk_rst_convert_drop_reason(drop_reason));
+		tcp_v6_send_reset(sk, skb, SK_RST_REASON_TCP_TIMEWAIT_SOCKET);
 		inet_twsk_deschedule_put(inet_twsk(sk));
 		goto discard_it;
 	case TCP_TW_SUCCESS:
-- 
2.37.3