From ca7d8a337bd3e3eda49ab1b4dfa09ac9b335a56b Mon Sep 17 00:00:00 2001 From: Xin Long Date: Tue, 5 Sep 2017 17:26:33 +0800 Subject: [PATCH] ip6_gre: update mtu properly in ip6gre_err [ Upstream commit 5c25f30c93fdc5bf25e62101aeaae7a4f9b421b3 ] Now when probessing ICMPV6_PKT_TOOBIG, ip6gre_err only subtracts the offset of gre header from mtu info. The expected mtu of gre device should also subtract gre header. Otherwise, the next packets still can't be sent out. Jianlin found this issue when using the topo: client(ip6gre)<---->(nic1)route(nic2)<----->(ip6gre)server and reducing nic2's mtu, then both tcp and sctp's performance with big size data became 0. This patch is to fix it by also subtracting grehdr (tun->tun_hlen) from mtu info when updating gre device's mtu in ip6gre_err(). It also needs to subtract ETH_HLEN if gre dev'type is ARPHRD_ETHER. Reported-by: Jianlin Shi Signed-off-by: Xin Long Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6_gre.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index d2844ee469cb..f78afe43bdff 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -432,7 +432,9 @@ static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt, } break; case ICMPV6_PKT_TOOBIG: - mtu = be32_to_cpu(info) - offset; + mtu = be32_to_cpu(info) - offset - t->tun_hlen; + if (t->dev->type == ARPHRD_ETHER) + mtu -= ETH_HLEN; if (mtu < IPV6_MIN_MTU) mtu = IPV6_MIN_MTU; t->dev->mtu = mtu;