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From: menglong8.dong@gmail.com
To: edumazet@google.com
Cc: rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net,
	yoshfuji@linux-ipv6.org, dsahern@kernel.org, kuba@kernel.org,
	pabeni@redhat.com, imagedong@tencent.com, kafai@fb.com,
	talalahmad@google.com, keescook@chromium.org,
	dongli.zhang@oracle.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, Jiang Biao <benbjiang@tencent.com>,
	Hao Peng <flyingpeng@tencent.com>
Subject: [PATCH net-next v2 8/9] net: tcp: add skb drop reasons to tcp tw code path
Date: Tue, 17 May 2022 16:10:07 +0800	[thread overview]
Message-ID: <20220517081008.294325-9-imagedong@tencent.com> (raw)
In-Reply-To: <20220517081008.294325-1-imagedong@tencent.com>

From: Menglong Dong <imagedong@tencent.com>

In order to get the reasons of skb drops, add a function argument of
type 'enum skb_drop_reason *reason' to tcp_timewait_state_process().

In the origin code, all packets to time-wait socket are treated as
dropping with kfree_skb(), which can make users confused. Therefore,
we use consume_skb() for the skbs that are 'good'. We can check the
value of 'reason' to decide use kfree_skb() or consume_skb().

The new reason 'TIMEWAIT' is added for the case that the skb is dropped
as the socket in time-wait state.

Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
v2:
- skb is not freed on TCP_TW_ACK and 'ret' is not initizalized, fix
  it (Eric Dumazet)
---
 include/linux/skbuff.h   |  5 +++++
 include/net/tcp.h        |  7 ++++---
 net/ipv4/tcp_ipv4.c      |  9 ++++++++-
 net/ipv4/tcp_minisocks.c | 24 ++++++++++++++++++++----
 net/ipv6/tcp_ipv6.c      |  9 ++++++++-
 5 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4578bbab5a3e..8d18fc5a5af6 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -560,6 +560,10 @@ struct sk_buff;
  * SKB_DROP_REASON_TCP_REQQFULLDROP
  *	request queue of the listen socket is full, corresponding to
  *	LINUX_MIB_TCPREQQFULLDROP
+ *
+ * SKB_DROP_REASON_TIMEWAIT
+ *	socket is in time-wait state and all packet that received will
+ *	be treated as 'drop', except a good 'SYN' packet
  */
 #define __DEFINE_SKB_DROP_REASON(FN)	\
 	FN(NOT_SPECIFIED)		\
@@ -631,6 +635,7 @@ struct sk_buff;
 	FN(TCP_ABORTONDATA)		\
 	FN(LISTENOVERFLOWS)		\
 	FN(TCP_REQQFULLDROP)		\
+	FN(TIMEWAIT)			\
 	FN(MAX)
 
 /* The reason of skb drop, which is used in kfree_skb_reason().
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 082dd0627e2e..88217b8d95ac 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -380,9 +380,10 @@ enum tcp_tw_status {
 };
 
 
-enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
-					      struct sk_buff *skb,
-					      const struct tcphdr *th);
+enum tcp_tw_status
+tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
+			   const struct tcphdr *th,
+			   enum skb_drop_reason *reason);
 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 			   struct request_sock *req, bool fastopen,
 			   bool *lost_race);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 708f92b03f42..3c163b54b0f8 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2134,7 +2134,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		inet_twsk_put(inet_twsk(sk));
 		goto csum_error;
 	}
-	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
+	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th,
+					   &drop_reason)) {
 	case TCP_TW_SYN: {
 		struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev),
 							&tcp_hashinfo, skb,
@@ -2150,11 +2151,17 @@ int tcp_v4_rcv(struct sk_buff *skb)
 			refcounted = false;
 			goto process;
 		}
+		/* TCP_FLAGS or NO_SOCKET? */
+		SKB_DR_SET(drop_reason, TCP_FLAGS);
 	}
 		/* to ACK */
 		fallthrough;
 	case TCP_TW_ACK:
 		tcp_v4_timewait_ack(sk, skb);
+		if (!drop_reason) {
+			consume_skb(skb);
+			return 0;
+		}
 		break;
 	case TCP_TW_RST:
 		tcp_v4_send_reset(sk, skb);
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 1a21018f6f64..329724118b7f 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -83,13 +83,15 @@ tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw,
  */
 enum tcp_tw_status
 tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
-			   const struct tcphdr *th)
+			   const struct tcphdr *th,
+			   enum skb_drop_reason *reason)
 {
 	struct tcp_options_received tmp_opt;
 	struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
 	bool paws_reject = false;
 
 	tmp_opt.saw_tstamp = 0;
+	*reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
 		tcp_parse_options(twsk_net(tw), skb, &tmp_opt, 0, NULL);
 
@@ -113,11 +115,16 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 			return tcp_timewait_check_oow_rate_limit(
 				tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2);
 
-		if (th->rst)
+		if (th->rst) {
+			SKB_DR_SET(*reason, TCP_RESET);
 			goto kill;
+		}
 
-		if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt))
+		if (th->syn && !before(TCP_SKB_CB(skb)->seq,
+				       tcptw->tw_rcv_nxt)) {
+			SKB_DR_SET(*reason, TCP_FLAGS);
 			return TCP_TW_RST;
+		}
 
 		/* Dup ACK? */
 		if (!th->ack ||
@@ -143,6 +150,9 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 		}
 
 		inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN);
+
+		/* skb should be free normally on this case. */
+		*reason = SKB_NOT_DROPPED_YET;
 		return TCP_TW_ACK;
 	}
 
@@ -174,6 +184,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 			 * protocol bug yet.
 			 */
 			if (twsk_net(tw)->ipv4.sysctl_tcp_rfc1337 == 0) {
+				SKB_DR_SET(*reason, TCP_RESET);
 kill:
 				inet_twsk_deschedule_put(tw);
 				return TCP_TW_SUCCESS;
@@ -216,11 +227,14 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 		if (isn == 0)
 			isn++;
 		TCP_SKB_CB(skb)->tcp_tw_isn = isn;
+		*reason = SKB_NOT_DROPPED_YET;
 		return TCP_TW_SYN;
 	}
 
-	if (paws_reject)
+	if (paws_reject) {
+		SKB_DR_SET(*reason, TCP_RFC7323_PAWS);
 		__NET_INC_STATS(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED);
+	}
 
 	if (!th->rst) {
 		/* In this case we must reset the TIMEWAIT timer.
@@ -232,9 +246,11 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
 		if (paws_reject || th->ack)
 			inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN);
 
+		SKB_DR_OR(*reason, TIMEWAIT);
 		return tcp_timewait_check_oow_rate_limit(
 			tw, skb, LINUX_MIB_TCPACKSKIPPEDTIMEWAIT);
 	}
+	SKB_DR_SET(*reason, TCP_RESET);
 	inet_twsk_put(tw);
 	return TCP_TW_SUCCESS;
 }
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 27c51991bd54..132b27763229 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1772,6 +1772,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 	}
 
 discard_it:
+	SKB_DR_OR(drop_reason, NOT_SPECIFIED);
 	kfree_skb_reason(skb, drop_reason);
 	return 0;
 
@@ -1795,7 +1796,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		goto csum_error;
 	}
 
-	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
+	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th,
+					   &drop_reason)) {
 	case TCP_TW_SYN:
 	{
 		struct sock *sk2;
@@ -1815,11 +1817,16 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 			refcounted = false;
 			goto process;
 		}
+		SKB_DR_SET(drop_reason, TCP_FLAGS);
 	}
 		/* to ACK */
 		fallthrough;
 	case TCP_TW_ACK:
 		tcp_v6_timewait_ack(sk, skb);
+		if (!drop_reason) {
+			consume_skb(skb);
+			return 0;
+		}
 		break;
 	case TCP_TW_RST:
 		tcp_v6_send_reset(sk, skb);
-- 
2.36.1


  parent reply	other threads:[~2022-05-17  8:14 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-17  8:09 [PATCH net-next v2 0/9] net: tcp: add skb drop reasons to tcp state change menglong8.dong
2022-05-17  8:10 ` [PATCH net-next v2 1/9] net: skb: introduce __DEFINE_SKB_DROP_REASON() to simply the code menglong8.dong
2022-05-18  1:14   ` Jakub Kicinski
2022-05-18  2:15     ` Menglong Dong
2022-05-17  8:10 ` [PATCH net-next v2 2/9] net: skb: introduce __skb_queue_purge_reason() menglong8.dong
2022-05-17  8:10 ` [PATCH net-next v2 3/9] net: sock: introduce sk_stream_kill_queues_reason() menglong8.dong
2022-05-17  8:10 ` [PATCH net-next v2 4/9] net: inet: add skb drop reason to inet_csk_destroy_sock() menglong8.dong
2022-05-17  8:10 ` [PATCH net-next v2 5/9] net: tcp: make tcp_rcv_synsent_state_process() return drop reasons menglong8.dong
2022-05-17  8:10 ` [PATCH net-next v2 6/9] net: tcp: make tcp_rcv_state_process() return drop reason menglong8.dong
2022-05-17  8:10 ` [PATCH net-next v2 7/9] net: tcp: add skb drop reasons to tcp connect requesting menglong8.dong
2022-05-17  8:10 ` menglong8.dong [this message]
2022-05-17  8:10 ` [PATCH net-next v2 9/9] net: tcp: add skb drop reasons to route_req() menglong8.dong

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