netdev - [PATCH net-next v2 7/9] net: tcp: use tcp_drop_reason() for tcp_rcv

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Date:   Fri, 18 Feb 2022 16:31:31 +0800
From:   menglong8.dong@...il.com
To:     dsahern@...nel.org, kuba@...nel.org
Cc:     edumazet@...gle.com, davem@...emloft.net, rostedt@...dmis.org,
        mingo@...hat.com, yoshfuji@...ux-ipv6.org, ast@...nel.org,
        daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com,
        imagedong@...cent.com, talalahmad@...gle.com,
        keescook@...omium.org, ilias.apalodimas@...aro.org, alobakin@...me,
        memxor@...il.com, atenart@...nel.org, bigeasy@...utronix.de,
        pabeni@...hat.com, linyunsheng@...wei.com, arnd@...db.de,
        yajun.deng@...ux.dev, roopa@...dia.com, willemb@...gle.com,
        vvs@...tuozzo.com, cong.wang@...edance.com,
        luiz.von.dentz@...el.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org, flyingpeng@...cent.com
Subject: [PATCH net-next v2 7/9] net: tcp: use tcp_drop_reason() for tcp_rcv_established()

From: Menglong Dong <imagedong@...cent.com>

Replace tcp_drop() used in tcp_rcv_established() with tcp_drop_reason().
Following drop reasons are added:

SKB_DROP_REASON_TCP_FLAGS

Signed-off-by: Menglong Dong <imagedong@...cent.com>
---
 include/linux/skbuff.h     | 1 +
 include/trace/events/skb.h | 1 +
 net/ipv4/tcp_input.c       | 9 +++++++--
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index f7f33c79945b..671db9f49efe 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -362,6 +362,7 @@ enum skb_drop_reason {
 					 * backlog (see
 					 * LINUX_MIB_TCPBACKLOGDROP)
 					 */
+	SKB_DROP_REASON_TCP_FLAGS,	/* TCP flags invalid */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index bfccd77e9071..d332e7313a61 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -32,6 +32,7 @@
 	   TCP_MD5UNEXPECTED)					\
 	EM(SKB_DROP_REASON_TCP_MD5FAILURE, TCP_MD5FAILURE)	\
 	EM(SKB_DROP_REASON_SOCKET_BACKLOG, SOCKET_BACKLOG)	\
+	EM(SKB_DROP_REASON_TCP_FLAGS, TCP_FLAGS)		\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0a2740add404..16ee1127e25d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5787,6 +5787,7 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
  */
 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 {
+	enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	const struct tcphdr *th = (const struct tcphdr *)skb->data;
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned int len = skb->len;
@@ -5875,6 +5876,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 				tp->rcv_rtt_last_tsecr = tp->rx_opt.rcv_tsecr;
 				return;
 			} else { /* Header too small */
+				reason = SKB_DROP_REASON_PKT_TOO_SMALL;
 				TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
 				goto discard;
 			}
@@ -5930,8 +5932,10 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 	if (len < (th->doff << 2) || tcp_checksum_complete(skb))
 		goto csum_error;
 
-	if (!th->ack && !th->rst && !th->syn)
+	if (!th->ack && !th->rst && !th->syn) {
+		reason = SKB_DROP_REASON_TCP_FLAGS;
 		goto discard;
+	}
 
 	/*
 	 *	Standard slow path.
@@ -5957,12 +5961,13 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
 	return;
 
 csum_error:
+	reason = SKB_DROP_REASON_TCP_CSUM;
 	trace_tcp_bad_csum(skb);
 	TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
 	TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
 
 discard:
-	tcp_drop(sk, skb);
+	tcp_drop_reason(sk, skb, reason);
 }
 EXPORT_SYMBOL(tcp_rcv_established);
 
-- 
2.34.1