Commit fa788d98 authored by Vincent Whitchurch's avatar Vincent Whitchurch Committed by David S. Miller
Browse files

packet: add sockopt to ignore outgoing packets 



Currently, the only way to ignore outgoing packets on a packet socket is
via the BPF filter.  With MSG_ZEROCOPY, packets that are looped into
AF_PACKET are copied in dev_queue_xmit_nit(), and this copy happens even
if the filter run from packet_rcv() would reject them.  So the presence
of a packet socket on the interface takes away the benefits of
MSG_ZEROCOPY, even if the packet socket is not interested in outgoing
packets.  (Even when MSG_ZEROCOPY is not used, the skb is unnecessarily
cloned, but the cost for that is much lower.)

Add a socket option to allow AF_PACKET sockets to ignore outgoing
packets to solve this.  Note that the *BSDs already have something
similar: BIOCSSEESENT/BIOCSDIRECTION and BIOCSDIRFILT.

The first intended user is lldpd.

Signed-off-by: default avatarVincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 05dcc712

include/linux/netdevice.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -2343,6 +2343,7 @@ static inline struct sk_buff *call_gro_receive_sk(gro_receive_sk_t cb, 




struct packet_type {

struct packet_type {

	__be16			type;	/* This is really htons(ether_type). */

	__be16			type;	/* This is really htons(ether_type). */

	bool			ignore_outgoing;

	struct net_device	*dev;	/* NULL is wildcarded here	     */

	struct net_device	*dev;	/* NULL is wildcarded here	     */

	int			(*func) (struct sk_buff *,

	int			(*func) (struct sk_buff *,

					 struct net_device *,

					 struct net_device *,

include/uapi/linux/if_packet.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -57,6 +57,7 @@ struct sockaddr_ll { 
#define PACKET_QDISC_BYPASS		20

#define PACKET_QDISC_BYPASS		20

#define PACKET_ROLLOVER_STATS		21

#define PACKET_ROLLOVER_STATS		21

#define PACKET_FANOUT_DATA		22

#define PACKET_FANOUT_DATA		22

#define PACKET_IGNORE_OUTGOING		23





#define PACKET_FANOUT_HASH		0

#define PACKET_FANOUT_HASH		0

#define PACKET_FANOUT_LB		1

#define PACKET_FANOUT_LB		1

net/core/dev.c

+3 −0
Original line number Original line Diff line number Diff line
@@ -1969,6 +1969,9 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev) 
	rcu_read_lock();

	rcu_read_lock();

again:

again:

	list_for_each_entry_rcu(ptype, ptype_list, list) {

	list_for_each_entry_rcu(ptype, ptype_list, list) {

		if (ptype->ignore_outgoing)

			continue;



		/* Never send packets back to the socket

		/* Never send packets back to the socket

		 * they originated from - MvS (miquels@drinkel.ow.org)

		 * they originated from - MvS (miquels@drinkel.ow.org)

		 */

		 */

net/packet/af_packet.c

+17 −0
Original line number Original line Diff line number Diff line
@@ -3805,6 +3805,20 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv 




		return fanout_set_data(po, optval, optlen);

		return fanout_set_data(po, optval, optlen);

	}

	}

	case PACKET_IGNORE_OUTGOING:

	{

		int val;



		if (optlen != sizeof(val))

			return -EINVAL;

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

			return -EFAULT;

		if (val < 0 || val > 1)

			return -EINVAL;



		po->prot_hook.ignore_outgoing = !!val;

		return 0;

	}

	case PACKET_TX_HAS_OFF:

	case PACKET_TX_HAS_OFF:

	{

	{

		unsigned int val;

		unsigned int val;
@@ -3928,6 +3942,9 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, 
			((u32)po->fanout->flags << 24)) :

			((u32)po->fanout->flags << 24)) :

		       0);

		       0);

		break;

		break;

	case PACKET_IGNORE_OUTGOING:

		val = po->prot_hook.ignore_outgoing;

		break;

	case PACKET_ROLLOVER_STATS:

	case PACKET_ROLLOVER_STATS:

		if (!po->rollover)

		if (!po->rollover)

			return -EINVAL;

			return -EINVAL;

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