[PATCH net-next v2 5/6] vxlan: fix snooping for link-local IPv6 addresses

[Matthias Schiffer]

If VXLAN is run over link-local IPv6 addresses, it is necessary to store
the ifindex in the FDB entries. Otherwise, the used interface is undefined
and unicast communication will most likely fail.

Signed-off-by: Matthias Schiffer <mschif...@universe-factory.net>
---

v2: use u32 instead of __u32

 drivers/net/vxlan.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 95a71546e8f2..2995b57a1551 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -941,16 +941,24 @@ static int vxlan_fdb_dump(struct sk_buff *skb, struct 
netlink_callback *cb,
  */
 static bool vxlan_snoop(struct net_device *dev,
                        union vxlan_addr *src_ip, const u8 *src_mac,
-                       __be32 vni)
+                       u32 src_ifindex, __be32 vni)
 {
        struct vxlan_dev *vxlan = netdev_priv(dev);
        struct vxlan_fdb *f;
+       u32 ifindex = 0;
+
+#if IS_ENABLED(CONFIG_IPV6)
+       if (src_ip->sa.sa_family == AF_INET6 &&
+           (ipv6_addr_type(&src_ip->sin6.sin6_addr) & IPV6_ADDR_LINKLOCAL))
+               ifindex = src_ifindex;
+#endif
 
        f = vxlan_find_mac(vxlan, src_mac, vni);
        if (likely(f)) {
                struct vxlan_rdst *rdst = first_remote_rcu(f);
 
-               if (likely(vxlan_addr_equal(&rdst->remote_ip, src_ip)))
+               if (likely(vxlan_addr_equal(&rdst->remote_ip, src_ip) &&
+                          rdst->remote_ifindex == ifindex))
                        return false;
 
                /* Don't migrate static entries, drop packets */
@@ -977,7 +985,7 @@ static bool vxlan_snoop(struct net_device *dev,
                                         vxlan->cfg.dst_port,
                                         vni,
                                         vxlan->default_dst.remote_vni,
-                                        0, NTF_SELF);
+                                        ifindex, NTF_SELF);
                spin_unlock(&vxlan->hash_lock);
        }
 
@@ -1246,6 +1254,7 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
                          struct sk_buff *skb, __be32 vni)
 {
        union vxlan_addr saddr;
+       u32 ifindex = skb->dev->ifindex;
 
        skb_reset_mac_header(skb);
        skb->protocol = eth_type_trans(skb, vxlan->dev);
@@ -1267,7 +1276,7 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
        }
 
        if ((vxlan->cfg.flags & VXLAN_F_LEARN) &&
-           vxlan_snoop(skb->dev, &saddr, eth_hdr(skb)->h_source, vni))
+           vxlan_snoop(skb->dev, &saddr, eth_hdr(skb)->h_source, ifindex, vni))
                return false;
 
        return true;
@@ -1978,7 +1987,8 @@ static void vxlan_encap_bypass(struct sk_buff *skb, 
struct vxlan_dev *src_vxlan,
        }
 
        if (dst_vxlan->cfg.flags & VXLAN_F_LEARN)
-               vxlan_snoop(skb->dev, &loopback, eth_hdr(skb)->h_source, vni);
+               vxlan_snoop(skb->dev, &loopback, eth_hdr(skb)->h_source, 0,
+                           vni);
 
        u64_stats_update_begin(&tx_stats->syncp);
        tx_stats->tx_packets++;
-- 
2.12.2