Commit a3bcc23e authored by Ben Greear's avatar Ben Greear Committed by David S. Miller
Browse files

af-packet: Add flag to distinguish VID 0 from no-vlan. 



Currently, user-space cannot determine if a 0 tcp_vlan_tci
means there is no VLAN tag or the VLAN ID was zero.

Add flag to make this explicit.  User-space can check for
TP_STATUS_VLAN_VALID || tp_vlan_tci > 0, which will be backwards
compatible. Older could would have just checked for tp_vlan_tci,
so it will work no worse than before.

Signed-off-by: default avatarBen Greear <greearb@candelatech.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 41be5a4a

include/linux/if_packet.h

+1 −0
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ struct tpacket_auxdata { 
#define TP_STATUS_COPY		0x2

#define TP_STATUS_LOSING	0x4

#define TP_STATUS_CSUMNOTREADY	0x8

#define TP_STATUS_VLAN_VALID   0x10 /* auxdata has valid tp_vlan_tci */



/* Tx ring - header status */

#define TP_STATUS_AVAILABLE	0x0

net/packet/af_packet.c

+12 −3
Original line number Diff line number Diff line
@@ -798,7 +798,12 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, 
			getnstimeofday(&ts);

		h.h2->tp_sec = ts.tv_sec;

		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;

		} else {

			h.h2->tp_vlan_tci = 0;

		}

		hdrlen = sizeof(*h.h2);

		break;

	default:
@@ -1725,8 +1730,12 @@ 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);

		if (vlan_tx_tag_present(skb)) {

			aux.tp_vlan_tci = vlan_tx_tag_get(skb);



			aux.tp_status |= TP_STATUS_VLAN_VALID;

		} else {

			aux.tp_vlan_tci = 0;

		}

		put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);

	}

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