netdev - [PATCH net-next V2 2/2] net-next: copy user configured flowlabel to reset packet

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Message-Id: <11eb1b2ccee19babfe2337e275b633ac766a6cff.1512161808.git.shli@fb.com>
Date:   Fri,  1 Dec 2017 13:00:44 -0800
From:   Shaohua Li <shli@...nel.org>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     kafai@...com, eric.dumazet@...il.com, flo@...rcot.fr,
        xiyou.wangcong@...il.com, tom@...bertland.com,
        Shaohua Li <shli@...com>
Subject: [PATCH net-next V2 2/2] net-next: copy user configured flowlabel to reset packet

From: Shaohua Li <shli@...com>

Reset packet doesn't use user configured flowlabel, instead, it always
uses 0. This will cause inconsistency for flowlabel. tw sock already
records flowlabel info, so we can directly use it.

Cc: Martin KaFai Lau <kafai@...com>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: Florent Fourcot <flo@...rcot.fr>
Cc: Cong Wang <xiyou.wangcong@...il.com>
Cc: Tom Herbert <tom@...bertland.com>
Signed-off-by: Shaohua Li <shli@...com>
---
 net/ipv6/tcp_ipv6.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index a1a5802..9b678cd 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -901,6 +901,8 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
 	struct sock *sk1 = NULL;
 #endif
 	int oif = 0;
+	u8 tclass = 0;
+	__be32 flowlabel = 0;
 
 	if (th->rst)
 		return;
@@ -954,7 +956,21 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
 		trace_tcp_send_reset(sk, skb);
 	}
 
-	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);
+	if (sk) {
+		if (sk_fullsock(sk)) {
+			struct ipv6_pinfo *np = inet6_sk(sk);
+
+			tclass = np->tclass;
+			flowlabel = np->flow_label & IPV6_FLOWLABEL_MASK;
+		} else {
+			struct inet_timewait_sock *tw = inet_twsk(sk);
+
+			tclass = tw->tw_tclass;
+			flowlabel = cpu_to_be32(tw->tw_flowlabel);
+		}
+	}
+	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1,
+		tclass, flowlabel);
 
 #ifdef CONFIG_TCP_MD5SIG
 out:
-- 
2.9.5