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Commit 8913336a authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

packet: add PACKET_RESERVE sockopt 



Add new sockopt to reserve some headroom in the mmaped ring frames in
front of the packet payload. This can be used f.i. when the VLAN header
needs to be (re)constructed to avoid moving the entire payload.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3ca4095f

include/linux/if_packet.h

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ struct sockaddr_ll 
#define PACKET_ORIGDEV			9

#define PACKET_VERSION			10

#define PACKET_HDRLEN			11

#define PACKET_RESERVE			12



struct tpacket_stats

{

net/packet/af_packet.c

+26 −3
Original line number Diff line number Diff line
@@ -188,6 +188,7 @@ struct packet_sock { 
	unsigned int		pg_vec_len;

	enum tpacket_versions	tp_version;

	unsigned int		tp_hdrlen;

	unsigned int		tp_reserve;

#endif

};
@@ -635,11 +636,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe 
		snaplen = res;



	if (sk->sk_type == SOCK_DGRAM) {

		macoff = netoff = TPACKET_ALIGN(po->tp_hdrlen) + 16;

		macoff = netoff = TPACKET_ALIGN(po->tp_hdrlen) + 16 +

				  po->tp_reserve;

	} else {

		unsigned maclen = skb_network_offset(skb);

		netoff = TPACKET_ALIGN(po->tp_hdrlen +

				       (maclen < 16 ? 16 : maclen));

				       (maclen < 16 ? 16 : maclen)) +

			po->tp_reserve;

		macoff = netoff - maclen;

	}
@@ -1448,6 +1451,19 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv 
			return -EINVAL;

		}

	}

	case PACKET_RESERVE:

	{

		unsigned int val;



		if (optlen != sizeof(val))

			return -EINVAL;

		if (po->pg_vec)

			return -EBUSY;

		if (copy_from_user(&val, optval, sizeof(val)))

			return -EFAULT;

		po->tp_reserve = val;

		return 0;

	}

#endif

	case PACKET_AUXDATA:

	{
@@ -1547,6 +1563,12 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, 
		}

		data = &val;

		break;

	case PACKET_RESERVE:

		if (len > sizeof(unsigned int))

			len = sizeof(unsigned int);

		val = po->tp_reserve;

		data = &val;

		break;

#endif

	default:

		return -ENOPROTOOPT;
@@ -1790,7 +1812,8 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing 
			return -EINVAL;

		if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))

			return -EINVAL;

		if (unlikely(req->tp_frame_size < po->tp_hdrlen))

		if (unlikely(req->tp_frame_size < po->tp_hdrlen +

						  po->tp_reserve))

			return -EINVAL;

		if (unlikely(req->tp_frame_size & (TPACKET_ALIGNMENT - 1)))

			return -EINVAL;