netfilter: xtables: limit xt_mac to ethernet devices
I do not see a point of allowing the MAC module to work with devices
that don't possibly have one, e.g. various tunnel interfaces such as
tun and sit.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/net/netfilter/xt_mac.c b/net/netfilter/xt_mac.c
index 2039d07..b971ce9 100644
--- a/net/netfilter/xt_mac.c
+++ b/net/netfilter/xt_mac.c
@@ -10,6 +10,7 @@
#include <linux/module.h>
#include <linux/skbuff.h>
+#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/etherdevice.h>
@@ -29,6 +30,8 @@
const struct xt_mac_info *info = par->matchinfo;
bool ret;
+ if (skb->dev == NULL || skb->dev->type != ARPHRD_ETHER)
+ return false;
if (skb_mac_header(skb) < skb->head)
return false;
if (skb_mac_header(skb) + ETH_HLEN > skb->data)