packet: deliver VLAN TCI to userspace

Store the VLAN tag in the auxillary data/tpacket2_hdr so userspace can
properly deal with hardware VLAN tagging/stripping.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_packet.h

@@ -59,6 +59,7 @@ struct tpacket_auxdata
 	__u32		tp_snaplen;
 	__u16		tp_mac;
 	__u16		tp_net;
+	__u16		tp_vlan_tci;
 };
 
 struct tpacket_hdr
@@ -90,6 +91,7 @@ struct tpacket2_hdr
 	__u16		tp_net;
 	__u32		tp_sec;
 	__u32		tp_nsec;
+	__u16		tp_vlan_tci;
 };
 
 #define TPACKET2_HDRLEN		(TPACKET_ALIGN(sizeof(struct tpacket2_hdr)) + sizeof(struct sockaddr_ll))

net/packet/af_packet.c

@@ -702,6 +702,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
 			getnstimeofday(&ts);
 		h.h2->tp_sec = ts.tv_sec;
 		h.h2->tp_nsec = ts.tv_nsec;
+		h.h2->tp_vlan_tci = skb->vlan_tci;
 		hdrlen = sizeof(*h.h2);
 		break;
 	default:
@@ -1172,6 +1173,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
 		aux.tp_snaplen = skb->len;
 		aux.tp_mac = 0;
 		aux.tp_net = skb_network_offset(skb);
+		aux.tp_vlan_tci = skb->vlan_tci;
 
 		put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
 	}