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ip_gre: Make o_seqno start from 0 in native mode

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[ Upstream commit ff827beb706ed719c766acf36449801ded0c17fc ]

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 <peilin.ye@bytedance.com>
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Peilin Ye 2022-04-21 15:07:57 -07:00 committed by Greg Kroah-Hartman
parent 69555bb27b
commit 685ff7d244
1 changed files with 3 additions and 5 deletions
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8
net/ipv4/ip_gre.c
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@ -432,14 +432,12 @@ 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);
}