net: ip6_gre: do not report erspan_ver for ip6gre or ip6gretap [Linux 5.0]

This Linux kernel change "net: ip6_gre: do not report erspan_ver for ip6gre or ip6gretap" is included in the Linux 5.0 release. This change is authored by Lorenzo Bianconi <lorenzo.bianconi [at] redhat.com> on Tue Feb 19 17:42:06 2019 +0100. The commit for this change in Linux stable tree is 103d024 (patch).

net: ip6_gre: do not report erspan_ver for ip6gre or ip6gretap

Report erspan version field to userspace in ip6gre_fill_info just for
erspan_v6 tunnels. Moreover report IFLA_GRE_ERSPAN_INDEX only for
erspan version 1.
The issue can be triggered with the following reproducer:

$ip link add name gre6 type ip6gre local 2001::1 remote 2002::2
$ip link set gre6 up
$ip -d link sh gre6
14: [email protected]: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1448 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/gre6 2001::1 peer 2002::2 promiscuity 0 minmtu 0 maxmtu 0
    ip6gre remote 2002::2 local 2001::1 hoplimit 64 encaplimit 4 tclass 0x00 flowlabel 0x00000 erspan_index 0 erspan_ver 0 addrgenmode eui64

Fixes: 94d7d8f29287 ("ip6_gre: add erspan v2 support")
Signed-off-by: Lorenzo Bianconi <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

There are 36 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 net/ipv6/ip6_gre.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 4389089..0fdd010 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -2104,9 +2104,23 @@ static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *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 (p->erspan_ver == 1 || p->erspan_ver == 2) {
+       if (!p->collect_md)
+           o_flags |= TUNNEL_KEY;
+
+       if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, p->erspan_ver))
+           goto nla_put_failure;
+
+       if (p->erspan_ver == 1) {
+           if (nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, p->index))
+               goto nla_put_failure;
+       } else {
+           if (nla_put_u8(skb, IFLA_GRE_ERSPAN_DIR, p->dir))
+               goto nla_put_failure;
+           if (nla_put_u16(skb, IFLA_GRE_ERSPAN_HWID, p->hwid))
+               goto nla_put_failure;
+       }
+   }

    if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
        nla_put_be16(skb, IFLA_GRE_IFLAGS,
@@ -2121,8 +2135,7 @@ static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *dev)
        nla_put_u8(skb, IFLA_GRE_ENCAP_LIMIT, p->encap_limit) ||
        nla_put_be32(skb, IFLA_GRE_FLOWINFO, p->flowinfo) ||
        nla_put_u32(skb, IFLA_GRE_FLAGS, p->flags) ||
-       nla_put_u32(skb, IFLA_GRE_FWMARK, p->fwmark) ||
-       nla_put_u32(skb, IFLA_GRE_ERSPAN_INDEX, p->index))
+       nla_put_u32(skb, IFLA_GRE_FWMARK, p->fwmark))
        goto nla_put_failure;

    if (nla_put_u16(skb, IFLA_GRE_ENCAP_TYPE,
@@ -2140,19 +2153,6 @@ static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *dev)
            goto nla_put_failure;
    }

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

 nla_put_failure:

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