| Message ID | 20180903142336.32122-1-vincent.whitchurch@axis.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2,net-next] packet: add sockopt to ignore outgoing packets | expand |
From: Vincent Whitchurch <vincent.whitchurch@axis.com> Date: Mon, 3 Sep 2018 16:23:36 +0200 > 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> > --- > v2: Stricter value validation. > Moved ignore check out of skb_loop_sk(). Applied, thank you.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index ca5ab98053c8..8ef14d9edc58 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2317,6 +2317,7 @@ static inline struct sk_buff *call_gro_receive_sk(gro_receive_sk_t cb, struct packet_type { __be16 type; /* This is really htons(ether_type). */ + bool ignore_outgoing; struct net_device *dev; /* NULL is wildcarded here */ int (*func) (struct sk_buff *, struct net_device *, diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h index 67b61d91d89b..467b654bd4c7 100644 --- a/include/uapi/linux/if_packet.h +++ b/include/uapi/linux/if_packet.h @@ -57,6 +57,7 @@ struct sockaddr_ll { #define PACKET_QDISC_BYPASS 20 #define PACKET_ROLLOVER_STATS 21 #define PACKET_FANOUT_DATA 22 +#define PACKET_IGNORE_OUTGOING 23 #define PACKET_FANOUT_HASH 0 #define PACKET_FANOUT_LB 1 diff --git a/net/core/dev.c b/net/core/dev.c index 325fc5088370..09dcf190c081 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1970,6 +1970,9 @@ 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 5610061e7f2e..23336498eb9f 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;
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> --- v2: Stricter value validation. Moved ignore check out of skb_loop_sk(). include/linux/netdevice.h | 1 + include/uapi/linux/if_packet.h | 1 + net/core/dev.c | 3 +++ net/packet/af_packet.c | 17 +++++++++++++++++ 4 files changed, 22 insertions(+)