vxlan: allow multiple VXLANs with same VNI for IPv6 link-local addresses

As link-local addresses are only valid for a single interface, we can allow
to use the same VNI for multiple independent VXLANs, as long as the used
interfaces are distinct. This way, VXLANs can always be used as a drop-in
replacement for VLANs with greater ID space.

This also extends VNI lookup to respect the ifindex when link-local IPv6
addresses are used, so using the same VNI on multiple interfaces can
actually work.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 45a8a54..653b2bb 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -226,7 +226,8 @@ static struct vxlan_sock *vxlan_find_sock(struct net *net, sa_family_t family,
        return NULL;
 }
 
-static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, __be32 vni)
+static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, int ifindex,
+                                          __be32 vni)
 {
        struct vxlan_dev *vxlan;
 
@@ -235,17 +236,27 @@ static struct vxlan_dev *vxlan_vs_find_vni(struct vxlan_sock *vs, __be32 vni)
                vni = 0;
 
        hlist_for_each_entry_rcu(vxlan, vni_head(vs, vni), hlist) {
-               if (vxlan->default_dst.remote_vni == vni)
-                       return vxlan;
+               if (vxlan->default_dst.remote_vni != vni)
+                       continue;
+
+               if (IS_ENABLED(CONFIG_IPV6)) {
+                       const struct vxlan_config *cfg = &vxlan->cfg;
+
+                       if ((cfg->flags & VXLAN_F_IPV6_LINKLOCAL) &&
+                           cfg->remote_ifindex != ifindex)
+                               continue;
+               }
+
+               return vxlan;
        }
 
        return NULL;
 }
 
 /* Look up VNI in a per net namespace table */
-static struct vxlan_dev *vxlan_find_vni(struct net *net, __be32 vni,
-                                       sa_family_t family, __be16 port,
-                                       u32 flags)
+static struct vxlan_dev *vxlan_find_vni(struct net *net, int ifindex,
+                                       __be32 vni, sa_family_t family,
+                                       __be16 port, u32 flags)
 {
        struct vxlan_sock *vs;
 
@@ -253,7 +264,7 @@ static struct vxlan_dev *vxlan_find_vni(struct net *net, __be32 vni,
        if (!vs)
                return NULL;
 
-       return vxlan_vs_find_vni(vs, vni);
+       return vxlan_vs_find_vni(vs, ifindex, vni);
 }
 
 /* Fill in neighbour message in skbuff. */
@@ -1360,7 +1371,7 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
 
        vni = vxlan_vni(vxlan_hdr(skb)->vx_vni);
 
-       vxlan = vxlan_vs_find_vni(vs, vni);
+       vxlan = vxlan_vs_find_vni(vs, skb->dev->ifindex, vni);
        if (!vxlan)
                goto drop;
 
@@ -2022,8 +2033,10 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,
 }
 
 static int encap_bypass_if_local(struct sk_buff *skb, struct net_device *dev,
-                                struct vxlan_dev *vxlan, union vxlan_addr *daddr,
-                                __be16 dst_port, __be32 vni, struct dst_entry *dst,
+                                struct vxlan_dev *vxlan,
+                                union vxlan_addr *daddr,
+                                __be16 dst_port, int dst_ifindex, __be32 vni,
+                                struct dst_entry *dst,
                                 u32 rt_flags)
 {
 #if IS_ENABLED(CONFIG_IPV6)
@@ -2039,7 +2052,7 @@ static int encap_bypass_if_local(struct sk_buff *skb, struct net_device *dev,
                struct vxlan_dev *dst_vxlan;
 
                dst_release(dst);
-               dst_vxlan = vxlan_find_vni(vxlan->net, vni,
+               dst_vxlan = vxlan_find_vni(vxlan->net, dst_ifindex, vni,
                                           daddr->sa.sa_family, dst_port,
                                           vxlan->cfg.flags);
                if (!dst_vxlan) {
@@ -2071,6 +2084,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
        struct dst_entry *ndst = NULL;
        __be32 vni, label;
        __u8 tos, ttl;
+       int ifindex;
        int err;
        u32 flags = vxlan->cfg.flags;
        bool udp_sum = false;
@@ -2091,6 +2105,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
 
                dst_port = rdst->remote_port ? rdst->remote_port : vxlan->cfg.dst_port;
                vni = (rdst->remote_vni) ? : default_vni;
+               ifindex = rdst->remote_ifindex;
                local_ip = vxlan->cfg.saddr;
                dst_cache = &rdst->dst_cache;
                md->gbp = skb->mark;
@@ -2124,6 +2139,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                dst = &remote_ip;
                dst_port = info->key.tp_dst ? : vxlan->cfg.dst_port;
                vni = tunnel_id_to_key32(info->key.tun_id);
+               ifindex = 0;
                dst_cache = &info->dst_cache;
                if (info->options_len)
                        md = ip_tunnel_info_opts(info);
@@ -2141,8 +2157,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                struct rtable *rt;
                __be16 df = 0;
 
-               rt = vxlan_get_route(vxlan, dev, sock4, skb,
-                                    rdst ? rdst->remote_ifindex : 0, tos,
+               rt = vxlan_get_route(vxlan, dev, sock4, skb, ifindex, tos,
                                     dst->sin.sin_addr.s_addr,
                                     &local_ip.sin.sin_addr.s_addr,
                                     dst_port, src_port,
@@ -2155,8 +2170,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                /* Bypass encapsulation if the destination is local */
                if (!info) {
                        err = encap_bypass_if_local(skb, dev, vxlan, dst,
-                                                   dst_port, vni, &rt->dst,
-                                                   rt->rt_flags);
+                                                   dst_port, ifindex, vni,
+                                                   &rt->dst, rt->rt_flags);
                        if (err)
                                goto out_unlock;
                } else if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT) {
@@ -2178,8 +2193,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
        } else {
                struct vxlan_sock *sock6 = rcu_dereference(vxlan->vn6_sock);
 
-               ndst = vxlan6_get_route(vxlan, dev, sock6, skb,
-                                       rdst ? rdst->remote_ifindex : 0, tos,
+               ndst = vxlan6_get_route(vxlan, dev, sock6, skb, ifindex, tos,
                                        label, &dst->sin6.sin6_addr,
                                        &local_ip.sin6.sin6_addr,
                                        dst_port, src_port,
@@ -2194,8 +2208,8 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                        u32 rt6i_flags = ((struct rt6_info *)ndst)->rt6i_flags;
 
                        err = encap_bypass_if_local(skb, dev, vxlan, dst,
-                                                   dst_port, vni, ndst,
-                                                   rt6i_flags);
+                                                   dst_port, ifindex, vni,
+                                                   ndst, rt6i_flags);
                        if (err)
                                goto out_unlock;
                }
@@ -2993,11 +3007,19 @@ static int vxlan_config_validate(struct net *src_net, struct vxlan_config *conf,
                if (tmp == old)
                        continue;
 
-               if (tmp->cfg.vni == conf->vni &&
-                   tmp->cfg.dst_port == conf->dst_port &&
-                   (tmp->cfg.flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)) ==
+               if (tmp->cfg.vni != conf->vni)
+                       continue;
+               if (tmp->cfg.dst_port != conf->dst_port)
+                       continue;
+               if ((tmp->cfg.flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)) !=
                    (conf->flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6)))
-                       return -EEXIST;
+                       continue;
+
+               if ((conf->flags & VXLAN_F_IPV6_LINKLOCAL) &&
+                   tmp->cfg.remote_ifindex != conf->remote_ifindex)
+                       continue;
+
+               return -EEXIST;
        }
 
        return 0;