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| author | Vincent Whitchurch <vincent.whitchurch@axis.com> | 2018-09-03 16:23:36 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-09-05 22:09:37 -0700 |
| commit | fa788d986a3aac5069378ed04697bd06f83d3488 (patch) | |
| tree | e335abac12b88e196f4c7c9e1012a66e93f53830 /net/packet | |
| parent | 05dcc71298643256948a2e17db7dbecc748719d2 (diff) | |
| download | lwn-fa788d986a3aac5069378ed04697bd06f83d3488.tar.gz lwn-fa788d986a3aac5069378ed04697bd06f83d3488.zip | |
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 <vincent.whitchurch@axis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
| -rw-r--r-- | net/packet/af_packet.c | 17 |
1 files changed, 17 insertions, 0 deletions
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; |