[PATCH net] erspan: set erspan_ver to 1 by default when adding an erspan dev

[PATCH net] erspan: set erspan_ver to 1 by default when adding an erspan dev

[Xin Long]

After erspan_ver is introudced, if erspan_ver is not set in iproute, its
value will be left 0 by default. Since Commit 02f99df1875c ("erspan: fix
invalid erspan version."), it has broken the traffic due to the version
check in erspan_xmit if users are not aware of 'erspan_ver' param, like
using an old version of iproute.

To fix this compatibility problem, it sets erspan_ver to 1 by default
when adding an erspan dev in erspan_setup. Note that we can't do it in
ipgre_netlink_parms, as this function is also used by ipgre_changelink.

Fixes: 02f99df1875c ("erspan: fix invalid erspan version.")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/ipv4/ip_gre.c  | 3 +++
 net/ipv6/ip6_gre.c | 1 +
 2 files changed, 4 insertions(+)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 51a5d06..ae714ae 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1508,11 +1508,14 @@ static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
 
 static void erspan_setup(struct net_device *dev)
 {
+	struct ip_tunnel *t = netdev_priv(dev);
+
 	ether_setup(dev);
 	dev->netdev_ops = &erspan_netdev_ops;
 	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
 	ip_tunnel_setup(dev, erspan_net_id);
+	t->erspan_ver = 1;
 }
 
 static const struct nla_policy ipgre_policy[IFLA_GRE_MAX + 1] = {
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 18a3794..e493b04 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -1778,6 +1778,7 @@ static void ip6gre_netlink_parms(struct nlattr *data[],
 	if (data[IFLA_GRE_COLLECT_METADATA])
 		parms->collect_md = true;
 
+	parms->erspan_ver = 1;
 	if (data[IFLA_GRE_ERSPAN_VER])
 		parms->erspan_ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]);
 
-- 
2.1.0

Re: [PATCH net] erspan: set erspan_ver to 1 by default when adding an erspan dev

[David Miller]

From: Xin Long <lucien.xin@gmail.com>
Date: Mon, 27 Aug 2018 18:41:32 +0800

> After erspan_ver is introudced, if erspan_ver is not set in iproute, its
> value will be left 0 by default. Since Commit 02f99df1875c ("erspan: fix
> invalid erspan version."), it has broken the traffic due to the version
> check in erspan_xmit if users are not aware of 'erspan_ver' param, like
> using an old version of iproute.
> 
> To fix this compatibility problem, it sets erspan_ver to 1 by default
> when adding an erspan dev in erspan_setup. Note that we can't do it in
> ipgre_netlink_parms, as this function is also used by ipgre_changelink.
> 
> Fixes: 02f99df1875c ("erspan: fix invalid erspan version.")
> Reported-by: Jianlin Shi <jishi@redhat.com>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>

Applied and queued up for -stable.