From 5c4e17bbb8dffc47417115107534ea32635355d6 Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Thu, 21 Apr 2022 15:08:38 -0700 Subject: [PATCH] ip6_gre: Make o_seqno start from 0 in native mode For IP6GRE and IP6GRETAP 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 the "if (tunnel->parms.collect_md)" clause in __gre6_xmit(), where tunnel->o_seqno is passed to gre_build_header() before getting incremented. Fixes: 3d8fd70921d8 ("gre: Support GRE over IPv6") Signed-off-by: Peilin Ye Acked-by: William Tu Signed-off-by: David S. Miller --- net/ipv6/ip6_gre.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 9762367361463..d9e4ac94eab44 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -724,6 +724,7 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb, { struct ip6_tnl *tunnel = netdev_priv(dev); __be16 protocol; + __be16 flags; if (dev->type == ARPHRD_ETHER) IPCB(skb)->flags = 0; @@ -739,7 +740,6 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb, if (tunnel->parms.collect_md) { struct ip_tunnel_info *tun_info; const struct ip_tunnel_key *key; - __be16 flags; int tun_hlen; tun_info = skb_tunnel_info_txcheck(skb); @@ -770,15 +770,14 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb, : 0); } else { - if (tunnel->parms.o_flags & TUNNEL_SEQ) - tunnel->o_seqno++; - if (skb_cow_head(skb, dev->needed_headroom ?: tunnel->hlen)) return -ENOMEM; - gre_build_header(skb, tunnel->tun_hlen, tunnel->parms.o_flags, + flags = tunnel->parms.o_flags; + + gre_build_header(skb, tunnel->tun_hlen, flags, protocol, tunnel->parms.o_key, - htonl(tunnel->o_seqno)); + (flags & TUNNEL_SEQ) ? htonl(tunnel->o_seqno++) : 0); } return ip6_tnl_xmit(skb, dev, dsfield, fl6, encap_limit, pmtu, -- 2.39.5