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Subject[PATCH net-next v2 6/6] vxlan: allow multiple VXLANs with same VNI for IPv6 link-local addresses
Date
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>
---

v2: use VXLAN_F_IPV6_LINKLOCAL in vxlan_vs_find_vni; rebase.

drivers/net/vxlan.c | 73 ++++++++++++++++++++++++++++++++++-------------------
1 file changed, 47 insertions(+), 26 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 2995b57a1551..9054245f0770 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -224,7 +224,8 @@ 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;

@@ -233,17 +234,27 @@ 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;

@@ -251,7 +262,7 @@ 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. */
@@ -1342,7 +1353,7 @@ 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;

@@ -2006,8 +2017,10 @@ 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)
@@ -2023,7 +2036,7 @@ 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) {
@@ -2055,6 +2068,7 @@ 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;
@@ -2075,6 +2089,7 @@ 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;
@@ -2108,6 +2123,7 @@ 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);
@@ -2125,8 +2141,7 @@ 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,
@@ -2139,8 +2154,8 @@ 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) {
@@ -2162,8 +2177,7 @@ 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,
@@ -2178,8 +2192,8 @@ 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;
}
@@ -2982,13 +2996,20 @@ 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)) ==
- (conf->flags & (VXLAN_F_RCV_FLAGS | VXLAN_F_IPV6))) {
- pr_info("duplicate VNI %u\n", be32_to_cpu(conf->vni));
- return -EEXIST;
- }
+ 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)))
+ continue;
+
+ if ((conf->flags & VXLAN_F_IPV6_LINKLOCAL) &&
+ tmp->cfg.remote_ifindex != conf->remote_ifindex)
+ continue;
+
+ pr_info("duplicate VNI %u\n", be32_to_cpu(conf->vni));
+ return -EEXIST;
}

return 0;
--
2.12.2
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