macsec: Don't rely solely on the dst MAC address to identify destination MACsec device

Offloading device drivers will mark offloaded MACsec SKBs with the
corresponding SCI in the skb_metadata_dst so the macsec rx handler will
know to which interface to divert those skbs, in case of a marked skb
and a mismatch on the dst MAC address, divert the skb to the macsec
net_device where the macsec rx_handler will be called to consider cases
where relying solely on the dst MAC address is insufficient.

One such instance is when using MACsec with a VLAN as an inner
header, where the packet structure is ETHERNET | SECTAG | VLAN.
In such a scenario, the dst MAC address in the ethernet header
will correspond to the VLAN MAC address, resulting in a mismatch.
Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
Reviewed-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macsec.c

@@ -1021,8 +1021,12 @@ static enum rx_handler_result handle_not_macsec(struct sk_buff *skb)
 		 * the SecTAG, so we have to deduce which port to deliver to.
 		 */
 		if (macsec_is_offloaded(macsec) && netif_running(ndev)) {
-			if (md_dst && md_dst->type == METADATA_MACSEC &&
-			    (!find_rx_sc(&macsec->secy, md_dst->u.macsec_info.sci)))
+			struct macsec_rx_sc *rx_sc = NULL;
+
+			if (md_dst && md_dst->type == METADATA_MACSEC)
+				rx_sc = find_rx_sc(&macsec->secy, md_dst->u.macsec_info.sci);
+
+			if (md_dst && md_dst->type == METADATA_MACSEC && !rx_sc)
 				continue;
 
 			if (ether_addr_equal_64bits(hdr->h_dest,
@@ -1047,7 +1051,13 @@ static enum rx_handler_result handle_not_macsec(struct sk_buff *skb)
 					nskb->pkt_type = PACKET_MULTICAST;
 
 				__netif_rx(nskb);
+			} else if (rx_sc || ndev->flags & IFF_PROMISC) {
+				skb->dev = ndev;
+				skb->pkt_type = PACKET_HOST;
+				ret = RX_HANDLER_ANOTHER;
+				goto out;
 			}
+
 			continue;
 		}