Re: [PATCH net] vxlan: Fix regression when dropping packets due to invalid src addresses

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On 6/2/24 10:37 AM, Ido Schimmel wrote:
On Fri, May 31, 2024 at 05:41:37PM +0200, Daniel Borkmann wrote:
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index f78dd0438843..7353f27b02dc 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -1605,6 +1605,7 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
  			  struct vxlan_sock *vs,
  			  struct sk_buff *skb, __be32 vni)
  {
+	bool learning = vxlan->cfg.flags & VXLAN_F_LEARN;
  	union vxlan_addr saddr;
  	u32 ifindex = skb->dev->ifindex;
@@ -1616,8 +1617,11 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
  	if (ether_addr_equal(eth_hdr(skb)->h_source, vxlan->dev->dev_addr))
  		return false;
- /* Ignore packets from invalid src-address */
-	if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
+	/* Ignore packets from invalid src-address when in learning mode,
+	 * otherwise let them through e.g. when originating from NOARP
+	 * devices with all-zero mac, etc.
+	 */
+	if (learning && !is_valid_ether_addr(eth_hdr(skb)->h_source))
  		return false;
/* Get address from the outer IP header */
@@ -1631,7 +1635,7 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
  #endif
  	}
- if ((vxlan->cfg.flags & VXLAN_F_LEARN) &&
+	if (learning &&
  	    vxlan_snoop(skb->dev, &saddr, eth_hdr(skb)->h_source, ifindex, vni))
  		return false;

Daniel, I think we can simply move this check out of the main path to
vxlan_snoop() which is only called when learning is enabled:

diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index 7496c14e8329..89f3945b448f 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -1446,6 +1446,10 @@ static bool vxlan_snoop(struct net_device *dev,
         struct vxlan_fdb *f;
         u32 ifindex = 0;
+ /* Ignore packets from invalid src-address */
+       if (!is_valid_ether_addr(src_mac))
+               return true;
+
  #if IS_ENABLED(CONFIG_IPV6)
         if (src_ip->sa.sa_family == AF_INET6 &&
             (ipv6_addr_type(&src_ip->sin6.sin6_addr) & IPV6_ADDR_LINKLOCAL))
@@ -1616,10 +1620,6 @@ static bool vxlan_set_mac(struct vxlan_dev *vxlan,
         if (ether_addr_equal(eth_hdr(skb)->h_source, vxlan->dev->dev_addr))
                 return false;
- /* Ignore packets from invalid src-address */
-       if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
-               return false;
-
         /* Get address from the outer IP header */
         if (vxlan_get_sk_family(vs) == AF_INET) {
                 saddr.sin.sin_addr.s_addr = ip_hdr(skb)->saddr;

WDYT?

Makes sense, that looks better. Will send a v2, thanks Ido!




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