From ff827beb706ed719c766acf36449801ded0c17fc Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Thu, 21 Apr 2022 15:07:57 -0700 Subject: [PATCH] ip_gre: Make o_seqno start from 0 in native mode For GRE and GRETAP devices, currently o_seqno starts from 1 in native mode. According to RFC 2890 2.2., "The first datagram is sent with a sequence number of 0." Fix it. It is worth mentioning that o_seqno already starts from 0 in collect_md mode, see gre_fb_xmit(), where tunnel->o_seqno is passed to gre_build_header() before getting incremented. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Peilin Ye Acked-by: William Tu Signed-off-by: David S. Miller --- net/ipv4/ip_gre.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 365caeb..21a8943 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -459,14 +459,12 @@ static void __gre_xmit(struct sk_buff *skb, struct net_device *dev, __be16 proto) { struct ip_tunnel *tunnel = netdev_priv(dev); - - if (tunnel->parms.o_flags & TUNNEL_SEQ) - tunnel->o_seqno++; + __be16 flags = tunnel->parms.o_flags; /* Push GRE header. */ gre_build_header(skb, tunnel->tun_hlen, - tunnel->parms.o_flags, proto, tunnel->parms.o_key, - htonl(tunnel->o_seqno)); + flags, proto, tunnel->parms.o_key, + (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++) : 0); ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol); } -- 2.7.4