Commit 3c84f8ea authored by Peilin Ye's avatar Peilin Ye Committed by Yongqiang Liu
Browse files

ip_gre: Make o_seqno start from 0 in native mode 

stable inclusion
from stable-4.19.242
commit fc926663635277fe808c5b68d0f74db1f40d67d8
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5A6BA


CVE: NA

--------------------------------

[ Upstream commit ff827beb ]

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: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarPeilin Ye <peilin.ye@bytedance.com>
Acked-by: default avatarWilliam Tu <u9012063@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarYongqiang Liu <liuyongqiang13@huawei.com>
parent f0a25b1e

net/ipv4/ip_gre.c

+3 −5
Original line number Diff line number Diff line
@@ -435,14 +435,12 @@ 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);

}