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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: Ben Greear <greearb@candelatech.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ben Greear 2011-06-01 06:49:10 +00:00 committed by David S. Miller
parent 41be5a4a36
commit a3bcc23e89
2 changed files with 13 additions and 3 deletions
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1
include/linux/if_packet.h
View File

@ -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

15
net/packet/af_packet.c
View File

@ -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;
h.h2->tp_vlan_tci = vlan_tx_tag_get(skb);
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);
aux.tp_vlan_tci = vlan_tx_tag_get(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);
}