Commit 27b29f63 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

bpf: add bpf_redirect() helper 



Existing bpf_clone_redirect() helper clones skb before redirecting
it to RX or TX of destination netdev.
Introduce bpf_redirect() helper that does that without cloning.

Benchmarked with two hosts using 10G ixgbe NICs.
One host is doing line rate pktgen.
Another host is configured as:
$ tc qdisc add dev $dev ingress
$ tc filter add dev $dev root pref 10 u32 match u32 0 0 flowid 1:2 \
   action bpf run object-file tcbpf1_kern.o section clone_redirect_xmit drop
so it receives the packet on $dev and immediately xmits it on $dev + 1
The section 'clone_redirect_xmit' in tcbpf1_kern.o file has the program
that does bpf_clone_redirect() and performance is 2.0 Mpps

$ tc filter add dev $dev root pref 10 u32 match u32 0 0 flowid 1:2 \
   action bpf run object-file tcbpf1_kern.o section redirect_xmit drop
which is using bpf_redirect() - 2.4 Mpps

and using cls_bpf with integrated actions as:
$ tc filter add dev $dev root pref 10 \
  bpf run object-file tcbpf1_kern.o section redirect_xmit integ_act classid 1
performance is 2.5 Mpps

To summarize:
u32+act_bpf using clone_redirect - 2.0 Mpps
u32+act_bpf using redirect - 2.4 Mpps
cls_bpf using redirect - 2.5 Mpps

For comparison linux bridge in this setup is doing 2.1 Mpps
and ixgbe rx + drop in ip_rcv - 7.8 Mpps

Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarJohn Fastabend <john.r.fastabend@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 045efa82

include/net/sch_generic.h

+1 −0
Original line number Diff line number Diff line
@@ -402,6 +402,7 @@ void __qdisc_calculate_pkt_len(struct sk_buff *skb, 
			       const struct qdisc_size_table *stab);

bool tcf_destroy(struct tcf_proto *tp, bool force);

void tcf_destroy_chain(struct tcf_proto __rcu **fl);

int skb_do_redirect(struct sk_buff *);



/* Reset all TX qdiscs greater then index of a device.  */

static inline void qdisc_reset_all_tx_gt(struct net_device *dev, unsigned int i)

include/uapi/linux/bpf.h

+8 −0
Original line number Diff line number Diff line
@@ -272,6 +272,14 @@ enum bpf_func_id { 
	BPF_FUNC_skb_get_tunnel_key,

	BPF_FUNC_skb_set_tunnel_key,

	BPF_FUNC_perf_event_read,	/* u64 bpf_perf_event_read(&map, index) */

	/**

	 * bpf_redirect(ifindex, flags) - redirect to another netdev

	 * @ifindex: ifindex of the net device

	 * @flags: bit 0 - if set, redirect to ingress instead of egress

	 *         other bits - reserved

	 * Return: TC_ACT_REDIRECT

	 */

	BPF_FUNC_redirect,

	__BPF_FUNC_MAX_ID,

};

include/uapi/linux/pkt_cls.h

+1 −0
Original line number Diff line number Diff line
@@ -87,6 +87,7 @@ enum { 
#define TC_ACT_STOLEN		4

#define TC_ACT_QUEUED		5

#define TC_ACT_REPEAT		6

#define TC_ACT_REDIRECT		7

#define TC_ACT_JUMP		0x10000000



/* Action type identifiers*/

net/core/dev.c

+8 −0
Original line number Diff line number Diff line
@@ -3670,6 +3670,14 @@ static inline struct sk_buff *handle_ing(struct sk_buff *skb, 
	case TC_ACT_QUEUED:

		kfree_skb(skb);

		return NULL;

	case TC_ACT_REDIRECT:

		/* skb_mac_header check was done by cls/act_bpf, so

		 * we can safely push the L2 header back before

		 * redirecting to another netdev

		 */

		__skb_push(skb, skb->mac_len);

		skb_do_redirect(skb);

		return NULL;

	default:

		break;

	}

net/core/filter.c

+44 −0
Original line number Diff line number Diff line
@@ -1427,6 +1427,48 @@ const struct bpf_func_proto bpf_clone_redirect_proto = { 
	.arg3_type      = ARG_ANYTHING,

};



struct redirect_info {

	u32 ifindex;

	u32 flags;

};



static DEFINE_PER_CPU(struct redirect_info, redirect_info);

static u64 bpf_redirect(u64 ifindex, u64 flags, u64 r3, u64 r4, u64 r5)

{

	struct redirect_info *ri = this_cpu_ptr(&redirect_info);



	ri->ifindex = ifindex;

	ri->flags = flags;

	return TC_ACT_REDIRECT;

}



int skb_do_redirect(struct sk_buff *skb)

{

	struct redirect_info *ri = this_cpu_ptr(&redirect_info);

	struct net_device *dev;



	dev = dev_get_by_index_rcu(dev_net(skb->dev), ri->ifindex);

	ri->ifindex = 0;

	if (unlikely(!dev)) {

		kfree_skb(skb);

		return -EINVAL;

	}



	if (BPF_IS_REDIRECT_INGRESS(ri->flags))

		return dev_forward_skb(dev, skb);



	skb->dev = dev;

	return dev_queue_xmit(skb);

}



const struct bpf_func_proto bpf_redirect_proto = {

	.func           = bpf_redirect,

	.gpl_only       = false,

	.ret_type       = RET_INTEGER,

	.arg1_type      = ARG_ANYTHING,

	.arg2_type      = ARG_ANYTHING,

};



static u64 bpf_get_cgroup_classid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)

{

	return task_get_classid((struct sk_buff *) (unsigned long) r1);
@@ -1607,6 +1649,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id) 
		return &bpf_skb_get_tunnel_key_proto;

	case BPF_FUNC_skb_set_tunnel_key:

		return bpf_get_skb_set_tunnel_key_proto();

	case BPF_FUNC_redirect:

		return &bpf_redirect_proto;

	default:

		return sk_filter_func_proto(func_id);

	}

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