Merge branch 'vlan_tpid'

Atzm Watanabe says:

====================
packet: deliver VLAN TPID to userspace

This patchset enables userspace to get VLAN TPID as well as the VLAN TCI.

After the 802.1AD support, userspace packet receivers (packet dumper,
software switch, and the like) need how to know VLAN TPID in order to
reconstruct original tagged frame.

v4: Simply use sizeof(tp_padding) for zeroing the padding bytes,
    commented by David Laight.
    Use __u16 for tp_vlan_tpid in tpacket_hdr_variant1,
    commented by Daniel Borkmann.

v3: Add a definition which indicates whether tp_vlan_tpid is valid.
    Explicitly define pad bytes for tpacket{2,3}_hdr and pick the area
    for tp_vlan_tpid from the definition.  Commented by David Laight.

v2: Add BUILD_BUG_ON() to make current aligned size of
    struct tpacket{2,3}_hdr clear.  Commented by Ben Hutchings.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 33 insertions, 14 deletions

diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index 1e24aa701cbd..e9d844c80c11 100644
--- a/include/uapi/linux/if_packet.h
+++ b/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;
-	__u16		tp_padding;
+	__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 {
@@ -154,6 +158,7 @@ struct tpacket3_hdr {
 	union {
 		struct tpacket_hdr_variant1 hv1;
 	};
+	__u8		tp_padding[8];
 };
 
 struct tpacket_bd_ts {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 24675f06f4fd..dd3840846ce2 100644
--- a/net/packet/af_packet.c
+++ b/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)
@@ -1812,6 +1815,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 	struct timespec ts;
 	__u32 ts_status;
 
+	/* struct tpacket{2,3}_hdr is aligned to a multiple of TPACKET_ALIGNMENT.
+	 * We may add members to them until current aligned size without forcing
+	 * userspace to call getsockopt(..., PACKET_HDRLEN, ...).
+	 */
+	BUILD_BUG_ON(TPACKET_ALIGN(sizeof(*h.h2)) != 32);
+	BUILD_BUG_ON(TPACKET_ALIGN(sizeof(*h.h3)) != 48);
+
 	if (skb->pkt_type == PACKET_LOOPBACK)
 		goto drop;
 
@@ -1918,11 +1928,13 @@ 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;
 		}
-		h.h2->tp_padding = 0;
+		memset(h.h2->tp_padding, 0, sizeof(h.h2->tp_padding));
 		hdrlen = sizeof(*h.h2);
 		break;
 	case TPACKET_V3:
@@ -1936,6 +1948,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 		h.h3->tp_net = netoff;
 		h.h3->tp_sec  = ts.tv_sec;
 		h.h3->tp_nsec = ts.tv_nsec;
+		memset(h.h3->tp_padding, 0, sizeof(h.h3->tp_padding));
 		hdrlen = sizeof(*h.h3);
 		break;
 	default:
@@ -2867,11 +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);
 	}