From ae8840825605f36f98f247323edc150e761cb64e Mon Sep 17 00:00:00 2001 From: David Stevens Date: Fri, 19 Apr 2013 00:36:26 +0000 Subject: [PATCH] VXLAN: Allow L2 redirection with L3 switching Allow L2 redirection when VXLAN L3 switching is enabled This patch restricts L3 switching to destination MAC addresses that are marked as routers in order to allow virtual IP appliances that do L2 redirection to function with VXLAN L3 switching enabled. We use L3 switching on VXLAN networks to avoid extra hops when the nominal router for cross-subnet traffic for a VM is remote and the ultimate destination may be local, or closer to the local node. Currently, the destination IP address takes precedence over the MAC address in all cases. Some network appliances receive packets for a virtualized IP address and redirect by changing the destination MAC address (only) to be the final destination for packet processing. VXLAN tunnel endpoints with L3 switching enabled may then overwrite this destination MAC address based on the packet IP address, resulting in potential loops and, at least, breaking L2 redirections that travel through tunnel endpoints. This patch limits L3 switching to the intended case where the original destination MAC address is a next-hop router and relies on the destination MAC address for all other cases, thus allowing L2 redirection and L3 switching to coexist peacefully. Signed-Off-By: David L Stevens Signed-off-by: David S. Miller --- drivers/net/vxlan.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 916a62149a12..a7fd9a089a35 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -98,6 +98,7 @@ struct vxlan_fdb { unsigned long used; struct vxlan_rdst remote; u16 state; /* see ndm_state */ + u8 flags; /* see ndm_flags */ u8 eth_addr[ETH_ALEN]; }; @@ -180,7 +181,7 @@ static int vxlan_fdb_info(struct sk_buff *skb, struct vxlan_dev *vxlan, ndm->ndm_family = AF_BRIDGE; ndm->ndm_state = fdb->state; ndm->ndm_ifindex = vxlan->dev->ifindex; - ndm->ndm_flags = NTF_SELF; + ndm->ndm_flags = fdb->flags; ndm->ndm_type = NDA_DST; if (send_eth && nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->eth_addr)) @@ -343,7 +344,8 @@ static int vxlan_fdb_append(struct vxlan_fdb *f, static int vxlan_fdb_create(struct vxlan_dev *vxlan, const u8 *mac, __be32 ip, __u16 state, __u16 flags, - __u32 port, __u32 vni, __u32 ifindex) + __u32 port, __u32 vni, __u32 ifindex, + __u8 ndm_flags) { struct vxlan_fdb *f; int notify = 0; @@ -360,6 +362,11 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan, f->updated = jiffies; notify = 1; } + if (f->flags != ndm_flags) { + f->flags = ndm_flags; + f->updated = jiffies; + notify = 1; + } if ((flags & NLM_F_APPEND) && is_multicast_ether_addr(f->eth_addr)) { int rc = vxlan_fdb_append(f, ip, port, vni, ifindex); @@ -387,6 +394,7 @@ static int vxlan_fdb_create(struct vxlan_dev *vxlan, f->remote.remote_ifindex = ifindex; f->remote.remote_next = NULL; f->state = state; + f->flags = ndm_flags; f->updated = f->used = jiffies; memcpy(f->eth_addr, mac, ETH_ALEN); @@ -480,7 +488,7 @@ static int vxlan_fdb_add(struct ndmsg *ndm, struct nlattr *tb[], spin_lock_bh(&vxlan->hash_lock); err = vxlan_fdb_create(vxlan, addr, ip, ndm->ndm_state, flags, port, - vni, ifindex); + vni, ifindex, ndm->ndm_flags); spin_unlock_bh(&vxlan->hash_lock); return err; @@ -568,7 +576,9 @@ static void vxlan_snoop(struct net_device *dev, err = vxlan_fdb_create(vxlan, src_mac, src_ip, NUD_REACHABLE, NLM_F_EXCL|NLM_F_CREATE, - vxlan_port, vxlan->default_dst.remote_vni, 0); + vxlan_port, + vxlan->default_dst.remote_vni, + 0, NTF_SELF); spin_unlock(&vxlan->hash_lock); } } @@ -1098,12 +1108,18 @@ static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev) if ((vxlan->flags & VXLAN_F_PROXY) && ntohs(eth->h_proto) == ETH_P_ARP) return arp_reduce(dev, skb); - else if ((vxlan->flags&VXLAN_F_RSC) && ntohs(eth->h_proto) == ETH_P_IP) - did_rsc = route_shortcircuit(dev, skb); f = vxlan_find_mac(vxlan, eth->h_dest); + did_rsc = false; + + if (f && (f->flags & NTF_ROUTER) && (vxlan->flags & VXLAN_F_RSC) && + ntohs(eth->h_proto) == ETH_P_IP) { + did_rsc = route_shortcircuit(dev, skb); + if (did_rsc) + f = vxlan_find_mac(vxlan, eth->h_dest); + } + if (f == NULL) { - did_rsc = false; rdst0 = &vxlan->default_dst; if (rdst0->remote_ip == htonl(INADDR_ANY) && -- 2.20.1