From fa788d986a3aac5069378ed04697bd06f83d3488 Mon Sep 17 00:00:00 2001 From: Vincent Whitchurch Date: Mon, 3 Sep 2018 16:23:36 +0200 Subject: 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: Vincent Whitchurch Signed-off-by: David S. Miller --- net/core/dev.c | 3 +++ net/packet/af_packet.c | 17 +++++++++++++++++ 2 files changed, 20 insertions(+) (limited to 'net') diff --git a/net/core/dev.c b/net/core/dev.c index 82114e1111e6..ca78dc5a79a3 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1969,6 +1969,9 @@ void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev) rcu_read_lock(); again: list_for_each_entry_rcu(ptype, ptype_list, list) { + if (ptype->ignore_outgoing) + continue; + /* Never send packets back to the socket * they originated from - MvS (miquels@drinkel.ow.org) */ diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 75c92a87e7b2..f85f67b5c1f4 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3805,6 +3805,20 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv 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: { unsigned int val; @@ -3928,6 +3942,9 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, ((u32)po->fanout->flags << 24)) : 0); break; + case PACKET_IGNORE_OUTGOING: + val = po->prot_hook.ignore_outgoing; + break; case PACKET_ROLLOVER_STATS: if (!po->rollover) return -EINVAL; -- cgit v1.2.3