net: ip6_gre: always reports o_key to userspace

As Erspan_v4, Erspan_v6 protocol relies on o_key to configure
session id header field. However TUNNEL_KEY bit is cleared in
ip6erspan_tunnel_xmit since ERSPAN protocol does not set the key field
of the external GRE header and so the configured o_key is not reported
to userspace. The issue can be triggered with the following reproducer:

$ip link add ip6erspan1 type ip6erspan local 2000::1 remote 2000::2 \
    key 1 seq erspan_ver 1
$ip link set ip6erspan1 up
ip -d link sh ip6erspan1

ip6erspan1@NONE: <BROADCAST,MULTICAST> mtu 1422 qdisc noop state DOWN mode DEFAULT
    link/ether ba:ff:09:24:c3:0e brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 1500
    ip6erspan remote 2000::2 local 2000::1 encaplimit 4 flowlabel 0x00000 ikey 0.0.0.1 iseq oseq

Fix the issue adding TUNNEL_KEY bit to the o_flags parameter in
ip6gre_fill_info

Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 4416368..801a9a0 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -2098,12 +2098,17 @@ static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
        struct ip6_tnl *t = netdev_priv(dev);
        struct __ip6_tnl_parm *p = &t->parms;
+       __be16 o_flags = p->o_flags;
+
+       if ((p->erspan_ver == 1 || p->erspan_ver == 2) &&
+           !p->collect_md)
+               o_flags |= TUNNEL_KEY;
 
        if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
            nla_put_be16(skb, IFLA_GRE_IFLAGS,
                         gre_tnl_flags_to_gre_flags(p->i_flags)) ||
            nla_put_be16(skb, IFLA_GRE_OFLAGS,
-                        gre_tnl_flags_to_gre_flags(p->o_flags)) ||
+                        gre_tnl_flags_to_gre_flags(o_flags)) ||
            nla_put_be32(skb, IFLA_GRE_IKEY, p->i_key) ||
            nla_put_be32(skb, IFLA_GRE_OKEY, p->o_key) ||
            nla_put_in6_addr(skb, IFLA_GRE_LOCAL, &p->laddr) ||