packet: deliver VLAN TPID to userspace

This enables userspace to get VLAN TPID as well as the VLAN TCI.
Signed-off-by: NAtzm Watanabe <atzm@stratosphere.co.jp>
Acked-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/uapi/linux/if_packet.h

@@ -84,17 +84,18 @@ struct tpacket_auxdata {
 	__u16		tp_mac;
 	__u16		tp_net;
 	__u16		tp_vlan_tci;
-	__u16		tp_padding;
+	__u16		tp_vlan_tpid;
 };
 
 /* Rx ring - header status */
-#define TP_STATUS_KERNEL	      0
-#define TP_STATUS_USER		(1 << 0)
-#define TP_STATUS_COPY		(1 << 1)
-#define TP_STATUS_LOSING	(1 << 2)
-#define TP_STATUS_CSUMNOTREADY	(1 << 3)
-#define TP_STATUS_VLAN_VALID	(1 << 4) /* auxdata has valid tp_vlan_tci */
-#define TP_STATUS_BLK_TMO	(1 << 5)
+#define TP_STATUS_KERNEL		      0
+#define TP_STATUS_USER			(1 << 0)
+#define TP_STATUS_COPY			(1 << 1)
+#define TP_STATUS_LOSING		(1 << 2)
+#define TP_STATUS_CSUMNOTREADY		(1 << 3)
+#define TP_STATUS_VLAN_VALID		(1 << 4) /* auxdata has valid tp_vlan_tci */
+#define TP_STATUS_BLK_TMO		(1 << 5)
+#define TP_STATUS_VLAN_TPID_VALID	(1 << 6) /* auxdata has valid tp_vlan_tpid */
 
 /* Tx ring - header status */
 #define TP_STATUS_AVAILABLE	      0
@@ -133,12 +134,15 @@ struct tpacket2_hdr {
 	__u32		tp_sec;
 	__u32		tp_nsec;
 	__u16		tp_vlan_tci;
-	__u8		tp_padding[6];
+	__u16		tp_vlan_tpid;
+	__u8		tp_padding[4];
 };
 
 struct tpacket_hdr_variant1 {
 	__u32	tp_rxhash;
 	__u32	tp_vlan_tci;
+	__u16	tp_vlan_tpid;
+	__u16	tp_padding;
 };
 
 struct tpacket3_hdr {
@@ -154,7 +158,7 @@ struct tpacket3_hdr {
 	union {
 		struct tpacket_hdr_variant1 hv1;
 	};
-	__u8		tp_padding[12];
+	__u8		tp_padding[8];
 };
 
 struct tpacket_bd_ts {

net/packet/af_packet.c

@@ -977,9 +977,11 @@ static void prb_fill_vlan_info(struct tpacket_kbdq_core *pkc,
 {
 	if (vlan_tx_tag_present(pkc->skb)) {
 		ppd->hv1.tp_vlan_tci = vlan_tx_tag_get(pkc->skb);
-		ppd->tp_status = TP_STATUS_VLAN_VALID;
+		ppd->hv1.tp_vlan_tpid = ntohs(pkc->skb->vlan_proto);
+		ppd->tp_status = TP_STATUS_VLAN_VALID | TP_STATUS_VLAN_TPID_VALID;
 	} else {
 		ppd->hv1.tp_vlan_tci = 0;
+		ppd->hv1.tp_vlan_tpid = 0;
 		ppd->tp_status = TP_STATUS_AVAILABLE;
 	}
 }
@@ -987,6 +989,7 @@ static void prb_fill_vlan_info(struct tpacket_kbdq_core *pkc,
 static void prb_run_all_ft_ops(struct tpacket_kbdq_core *pkc,
 			struct tpacket3_hdr *ppd)
 {
+	ppd->hv1.tp_padding = 0;
 	prb_fill_vlan_info(pkc, ppd);
 
 	if (pkc->feature_req_word & TP_FT_REQ_FILL_RXHASH)
@@ -1925,9 +1928,11 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		h.h2->tp_nsec = ts.tv_nsec;
 		if (vlan_tx_tag_present(skb)) {
 			h.h2->tp_vlan_tci = vlan_tx_tag_get(skb);
-			status |= TP_STATUS_VLAN_VALID;
+			h.h2->tp_vlan_tpid = ntohs(skb->vlan_proto);
+			status |= TP_STATUS_VLAN_VALID | TP_STATUS_VLAN_TPID_VALID;
 		} else {
 			h.h2->tp_vlan_tci = 0;
+			h.h2->tp_vlan_tpid = 0;
 		}
 		memset(h.h2->tp_padding, 0, sizeof(h.h2->tp_padding));
 		hdrlen = sizeof(*h.h2);
@@ -2875,11 +2880,12 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
 		aux.tp_net = skb_network_offset(skb);
 		if (vlan_tx_tag_present(skb)) {
 			aux.tp_vlan_tci = vlan_tx_tag_get(skb);
-			aux.tp_status |= TP_STATUS_VLAN_VALID;
+			aux.tp_vlan_tpid = ntohs(skb->vlan_proto);
+			aux.tp_status |= TP_STATUS_VLAN_VALID | TP_STATUS_VLAN_TPID_VALID;
 		} else {
 			aux.tp_vlan_tci = 0;
+			aux.tp_vlan_tpid = 0;
 		}
-		aux.tp_padding = 0;
 		put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
 	}