net: ip_gre: do not report erspan_ver for gre or gretap [Linux 5.0]

This Linux kernel change "net: ip_gre: do not report erspan_ver for gre or gretap" is included in the Linux 5.0 release. This change is authored by Lorenzo Bianconi <lorenzo.bianconi [at] redhat.com> on Tue Feb 19 17:42:05 2019 +0100. The commit for this change in Linux stable tree is 2bdf700 (patch).

net: ip_gre: do not report erspan_ver for gre or gretap

Report erspan version field to userspace in ipgre_fill_info just for
erspan tunnels. The issue can be triggered with the following reproducer:

$ip link add name gre1 type gre local 192.168.0.1 remote 192.168.1.1
$ip link set dev gre1 up
$ip -d link sh gre1
13: [email protected]: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/gre 192.168.0.1 peer 192.168.1.1 promiscuity 0 minmtu 0 maxmtu 0
    gre remote 192.168.1.1 local 192.168.0.1 ttl inherit erspan_ver 0 addrgenmode eui64 numtxqueues 1 numrxqueues 1

Fixes: f551c91de262 ("net: erspan: introduce erspan v2 for ip_gre")
Signed-off-by: Lorenzo Bianconi <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

There are 33 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 net/ipv4/ip_gre.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 3978f80..6ae89f2 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1457,9 +1457,23 @@ static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
    struct ip_tunnel_parm *p = &t->parms;
    __be16 o_flags = p->o_flags;

-   if ((t->erspan_ver == 1 || t->erspan_ver == 2) &&
-       !t->collect_md)
-       o_flags |= TUNNEL_KEY;
+   if (t->erspan_ver == 1 || t->erspan_ver == 2) {
+       if (!t->collect_md)
+           o_flags |= TUNNEL_KEY;
+
+       if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, t->erspan_ver))
+           goto nla_put_failure;
+
+       if (t->erspan_ver == 1) {
+           if (nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, t->index))
+               goto nla_put_failure;
+       } else {
+           if (nla_put_u8(skb, IFLA_GRE_ERSPAN_DIR, t->dir))
+               goto nla_put_failure;
+           if (nla_put_u16(skb, IFLA_GRE_ERSPAN_HWID, t->hwid))
+               goto nla_put_failure;
+       }
+   }

    if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
        nla_put_be16(skb, IFLA_GRE_IFLAGS,
@@ -1495,19 +1509,6 @@ static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
            goto nla_put_failure;
    }

-   if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, t->erspan_ver))
-       goto nla_put_failure;
-
-   if (t->erspan_ver == 1) {
-       if (nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, t->index))
-           goto nla_put_failure;
-   } else if (t->erspan_ver == 2) {
-       if (nla_put_u8(skb, IFLA_GRE_ERSPAN_DIR, t->dir))
-           goto nla_put_failure;
-       if (nla_put_u16(skb, IFLA_GRE_ERSPAN_HWID, t->hwid))
-           goto nla_put_failure;
-   }
-
    return 0;

 nla_put_failure:

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