[PATCH net-next V3 2/3] net-next: copy user configured flowlabel to reset packet

[Shaohua Li]

From: Shaohua Li <s...@fb.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 <ka...@fb.com>
Cc: Eric Dumazet <eric.duma...@gmail.com>
Cc: Florent Fourcot <f...@fourcot.fr>
Cc: Cong Wang <xiyou.wangc...@gmail.com>
Cc: Tom Herbert <t...@herbertland.com>
Signed-off-by: Shaohua Li <s...@fb.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 1e4ce06..b8383be 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -902,6 +902,8 @@ 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;
@@ -955,7 +957,21 @@ 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