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Commit 57f89bfa authored by Ben Greear's avatar Ben Greear Committed by David S. Miller
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network: Allow af_packet to transmit +4 bytes for VLAN packets. 



This allows user-space to send a '1500' MTU VLAN packet on a
1500 MTU ethernet frame.  The extra 4 bytes of a VLAN header is
not usually charged against the MTU when other parts of the
network stack is transmitting vlans...

Signed-off-by: default avatarBen Greear <greearb@candelatech.com>
Reviewed-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ab889e66

net/packet/af_packet.c

+29 −2
Original line number Diff line number Diff line
@@ -465,7 +465,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock, 
	 */



	err = -EMSGSIZE;

	if (len > dev->mtu + dev->hard_header_len)

	if (len > dev->mtu + dev->hard_header_len + VLAN_HLEN)

		goto out_unlock;



	if (!skb) {
@@ -496,6 +496,19 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock, 
		goto retry;

	}



	if (len > (dev->mtu + dev->hard_header_len)) {

		/* Earlier code assumed this would be a VLAN pkt,

		 * double-check this now that we have the actual

		 * packet in hand.

		 */

		struct ethhdr *ehdr;

		skb_reset_mac_header(skb);

		ehdr = eth_hdr(skb);

		if (ehdr->h_proto != htons(ETH_P_8021Q)) {

			err = -EMSGSIZE;

			goto out_unlock;

		}

	}



	skb->protocol = proto;

	skb->dev = dev;
@@ -1199,7 +1212,7 @@ static int packet_snd(struct socket *sock, 
	}



	err = -EMSGSIZE;

	if (!gso_type && (len > dev->mtu+reserve))

	if (!gso_type && (len > dev->mtu + reserve + VLAN_HLEN))

		goto out_unlock;



	err = -ENOBUFS;
@@ -1224,6 +1237,20 @@ static int packet_snd(struct socket *sock, 
	if (err < 0)

		goto out_free;



	if (!gso_type && (len > dev->mtu + reserve)) {

		/* Earlier code assumed this would be a VLAN pkt,

		 * double-check this now that we have the actual

		 * packet in hand.

		 */

		struct ethhdr *ehdr;

		skb_reset_mac_header(skb);

		ehdr = eth_hdr(skb);

		if (ehdr->h_proto != htons(ETH_P_8021Q)) {

			err = -EMSGSIZE;

			goto out_free;

		}

	}



	skb->protocol = proto;

	skb->dev = dev;

	skb->priority = sk->sk_priority;