offload - ignore ethernet packets not destined for us

Test: atest, TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Icabd1db48a1189425a941384d534c0f18bf20827

Tethering/bpf_progs/offload.c

@@ -50,6 +50,9 @@ static inline __always_inline int do_forward6(struct __sk_buff* skb, const bool
     struct ethhdr* eth = is_ethernet ? data : NULL;  // used iff is_ethernet
     struct ipv6hdr* ip6 = is_ethernet ? (void*)(eth + 1) : data;
 
+    // Require ethernet dst mac address to be our unicast address.
+    if (is_ethernet && (skb->pkt_type != PACKET_HOST)) return TC_ACT_OK;
+
     // Must be meta-ethernet IPv6 frame
     if (skb->protocol != htons(ETH_P_IPV6)) return TC_ACT_OK;