bpf: Add test for bpf_redirect to ipip/ip6tnl

The test creates two netns, ns1 and ns2.  The host (the default netns)
has an ipip or ip6tnl dev configured for tunneling traffic to the ns2.

    ping VIPS from ns1 <----> host <--tunnel--> ns2 (VIPs at loopback)

The test is to have ns1 pinging VIPs configured at the loopback
interface in ns2.

The VIPs are 10.10.1.102 and 2401:face::66 (which are configured
at lo@ns2). [Note: 0x66 => 102].

At ns1, the VIPs are routed _via_ the host.

At the host, bpf programs are installed at the veth to redirect packets
from a veth to the ipip/ip6tnl.  The test is configured in a way so
that both ingress and egress can be tested.

At ns2, the ipip/ip6tnl dev is configured with the local and remote address
specified.  The return path is routed to the dev ipip/ip6tnl.

During egress test, the host also locally tests pinging the VIPs to ensure
that bpf_redirect at egress also works for the direct egress (i.e. not
forwarding from dev ve1 to ve2).

Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 486 insertions, 0 deletions

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 12b7304..72c5867 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -27,6 +27,7 @@ hostprogs-y += xdp2
 hostprogs-y += test_current_task_under_cgroup
 hostprogs-y += trace_event
 hostprogs-y += sampleip
+hostprogs-y += tc_l2_redirect
 
 test_verifier-objs := test_verifier.o libbpf.o
 test_maps-objs := test_maps.o libbpf.o
@@ -56,6 +57,7 @@ test_current_task_under_cgroup-objs := bpf_load.o libbpf.o \
 				       test_current_task_under_cgroup_user.o
 trace_event-objs := bpf_load.o libbpf.o trace_event_user.o
 sampleip-objs := bpf_load.o libbpf.o sampleip_user.o
+tc_l2_redirect-objs := bpf_load.o libbpf.o tc_l2_redirect_user.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
@@ -72,6 +74,7 @@ always += test_probe_write_user_kern.o
 always += trace_output_kern.o
 always += tcbpf1_kern.o
 always += tcbpf2_kern.o
+always += tc_l2_redirect_kern.o
 always += lathist_kern.o
 always += offwaketime_kern.o
 always += spintest_kern.o
@@ -111,6 +114,7 @@ HOSTLOADLIBES_xdp2 += -lelf
 HOSTLOADLIBES_test_current_task_under_cgroup += -lelf
 HOSTLOADLIBES_trace_event += -lelf
 HOSTLOADLIBES_sampleip += -lelf
+HOSTLOADLIBES_tc_l2_redirect += -l elf
 
 # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
 #  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
diff --git a/samples/bpf/tc_l2_redirect.sh b/samples/bpf/tc_l2_redirect.sh
new file mode 100755
index 0000000..80a05591
--- /dev/null
+++ b/samples/bpf/tc_l2_redirect.sh
@@ -0,0 +1,173 @@
+#!/bin/bash
+
+[[ -z $TC ]] && TC='tc'
+[[ -z $IP ]] && IP='ip'
+
+REDIRECT_USER='./tc_l2_redirect'
+REDIRECT_BPF='./tc_l2_redirect_kern.o'
+
+RP_FILTER=$(< /proc/sys/net/ipv4/conf/all/rp_filter)
+IPV6_FORWARDING=$(< /proc/sys/net/ipv6/conf/all/forwarding)
+
+function config_common {
+	local tun_type=$1
+
+	$IP netns add ns1
+	$IP netns add ns2
+	$IP link add ve1 type veth peer name vens1
+	$IP link add ve2 type veth peer name vens2
+	$IP link set dev ve1 up
+	$IP link set dev ve2 up
+	$IP link set dev ve1 mtu 1500
+	$IP link set dev ve2 mtu 1500
+	$IP link set dev vens1 netns ns1
+	$IP link set dev vens2 netns ns2
+
+	$IP -n ns1 link set dev lo up
+	$IP -n ns1 link set dev vens1 up
+	$IP -n ns1 addr add 10.1.1.101/24 dev vens1
+	$IP -n ns1 addr add 2401:db01::65/64 dev vens1 nodad
+	$IP -n ns1 route add default via 10.1.1.1 dev vens1
+	$IP -n ns1 route add default via 2401:db01::1 dev vens1
+
+	$IP -n ns2 link set dev lo up
+	$IP -n ns2 link set dev vens2 up
+	$IP -n ns2 addr add 10.2.1.102/24 dev vens2
+	$IP -n ns2 addr add 2401:db02::66/64 dev vens2 nodad
+	$IP -n ns2 addr add 10.10.1.102 dev lo
+	$IP -n ns2 addr add 2401:face::66/64 dev lo nodad
+	$IP -n ns2 link add ipt2 type ipip local 10.2.1.102 remote 10.2.1.1
+	$IP -n ns2 link add ip6t2 type ip6tnl mode any local 2401:db02::66 remote 2401:db02::1
+	$IP -n ns2 link set dev ipt2 up
+	$IP -n ns2 link set dev ip6t2 up
+	$IP netns exec ns2 $TC qdisc add dev vens2 clsact
+	$IP netns exec ns2 $TC filter add dev vens2 ingress bpf da obj $REDIRECT_BPF sec drop_non_tun_vip
+	if [[ $tun_type == "ipip" ]]; then
+		$IP -n ns2 route add 10.1.1.0/24 dev ipt2
+		$IP netns exec ns2 sysctl -q -w net.ipv4.conf.all.rp_filter=0
+		$IP netns exec ns2 sysctl -q -w net.ipv4.conf.ipt2.rp_filter=0
+	else
+		$IP -n ns2 route add 10.1.1.0/24 dev ip6t2
+		$IP -n ns2 route add 2401:db01::/64 dev ip6t2
+		$IP netns exec ns2 sysctl -q -w net.ipv4.conf.all.rp_filter=0
+		$IP netns exec ns2 sysctl -q -w net.ipv4.conf.ip6t2.rp_filter=0
+	fi
+
+	$IP addr add 10.1.1.1/24 dev ve1
+	$IP addr add 2401:db01::1/64 dev ve1 nodad
+	$IP addr add 10.2.1.1/24 dev ve2
+	$IP addr add 2401:db02::1/64 dev ve2 nodad
+
+	$TC qdisc add dev ve2 clsact
+	$TC filter add dev ve2 ingress bpf da obj $REDIRECT_BPF sec l2_to_iptun_ingress_forward
+
+	sysctl -q -w net.ipv4.conf.all.rp_filter=0
+	sysctl -q -w net.ipv6.conf.all.forwarding=1
+}
+
+function cleanup {
+	set +e
+	[[ -z $DEBUG ]] || set +x
+	$IP netns delete ns1 >& /dev/null
+	$IP netns delete ns2 >& /dev/null
+	$IP link del ve1 >& /dev/null
+	$IP link del ve2 >& /dev/null
+	$IP link del ipt >& /dev/null
+	$IP link del ip6t >& /dev/null
+	sysctl -q -w net.ipv4.conf.all.rp_filter=$RP_FILTER
+	sysctl -q -w net.ipv6.conf.all.forwarding=$IPV6_FORWARDING
+	rm -f /sys/fs/bpf/tc/globals/tun_iface
+	[[ -z $DEBUG ]] || set -x
+	set -e
+}
+
+function l2_to_ipip {
+	echo -n "l2_to_ipip $1: "
+
+	local dir=$1
+
+	config_common ipip
+
+	$IP link add ipt type ipip external
+	$IP link set dev ipt up
+	sysctl -q -w net.ipv4.conf.ipt.rp_filter=0
+	sysctl -q -w net.ipv4.conf.ipt.forwarding=1
+
+	if [[ $dir == "egress" ]]; then
+		$IP route add 10.10.1.0/24 via 10.2.1.102 dev ve2
+		$TC filter add dev ve2 egress bpf da obj $REDIRECT_BPF sec l2_to_iptun_ingress_redirect
+		sysctl -q -w net.ipv4.conf.ve1.forwarding=1
+	else
+		$TC qdisc add dev ve1 clsact
+		$TC filter add dev ve1 ingress bpf da obj $REDIRECT_BPF sec l2_to_iptun_ingress_redirect
+	fi
+
+	$REDIRECT_USER -U /sys/fs/bpf/tc/globals/tun_iface -i $(< /sys/class/net/ipt/ifindex)
+
+	$IP netns exec ns1 ping -c1 10.10.1.102 >& /dev/null
+
+	if [[ $dir == "egress" ]]; then
+		# test direct egress to ve2 (i.e. not forwarding from
+		# ve1 to ve2).
+		ping -c1 10.10.1.102 >& /dev/null
+	fi
+
+	cleanup
+
+	echo "OK"
+}
+
+function l2_to_ip6tnl {
+	echo -n "l2_to_ip6tnl $1: "
+
+	local dir=$1
+
+	config_common ip6tnl
+
+	$IP link add ip6t type ip6tnl mode any external
+	$IP link set dev ip6t up
+	sysctl -q -w net.ipv4.conf.ip6t.rp_filter=0
+	sysctl -q -w net.ipv4.conf.ip6t.forwarding=1
+
+	if [[ $dir == "egress" ]]; then
+		$IP route add 10.10.1.0/24 via 10.2.1.102 dev ve2
+		$IP route add 2401:face::/64 via 2401:db02::66 dev ve2
+		$TC filter add dev ve2 egress bpf da obj $REDIRECT_BPF sec l2_to_ip6tun_ingress_redirect
+		sysctl -q -w net.ipv4.conf.ve1.forwarding=1
+	else
+		$TC qdisc add dev ve1 clsact
+		$TC filter add dev ve1 ingress bpf da obj $REDIRECT_BPF sec l2_to_ip6tun_ingress_redirect
+	fi
+
+	$REDIRECT_USER -U /sys/fs/bpf/tc/globals/tun_iface -i $(< /sys/class/net/ip6t/ifindex)
+
+	$IP netns exec ns1 ping -c1 10.10.1.102 >& /dev/null
+	$IP netns exec ns1 ping -6 -c1 2401:face::66 >& /dev/null
+
+	if [[ $dir == "egress" ]]; then
+		# test direct egress to ve2 (i.e. not forwarding from
+		# ve1 to ve2).
+		ping -c1 10.10.1.102 >& /dev/null
+		ping -6 -c1 2401:face::66 >& /dev/null
+	fi
+
+	cleanup
+
+	echo "OK"
+}
+
+cleanup
+test_names="l2_to_ipip l2_to_ip6tnl"
+test_dirs="ingress egress"
+if [[ $# -ge 2 ]]; then
+	test_names=$1
+	test_dirs=$2
+elif [[ $# -ge 1 ]]; then
+	test_names=$1
+fi
+
+for t in $test_names; do
+	for d in $test_dirs; do
+		$t $d
+	done
+done
diff --git a/samples/bpf/tc_l2_redirect_kern.c b/samples/bpf/tc_l2_redirect_kern.c
new file mode 100644
index 0000000..92a4472
--- /dev/null
+++ b/samples/bpf/tc_l2_redirect_kern.c
@@ -0,0 +1,236 @@
+/* Copyright (c) 2016 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/if_packet.h>
+#include <uapi/linux/ip.h>
+#include <uapi/linux/ipv6.h>
+#include <uapi/linux/in.h>
+#include <uapi/linux/tcp.h>
+#include <uapi/linux/filter.h>
+#include <uapi/linux/pkt_cls.h>
+#include <net/ipv6.h>
+#include "bpf_helpers.h"
+
+#define _htonl __builtin_bswap32
+
+#define PIN_GLOBAL_NS		2
+struct bpf_elf_map {
+	__u32 type;
+	__u32 size_key;
+	__u32 size_value;
+	__u32 max_elem;
+	__u32 flags;
+	__u32 id;
+	__u32 pinning;
+};
+
+/* copy of 'struct ethhdr' without __packed */
+struct eth_hdr {
+	unsigned char   h_dest[ETH_ALEN];
+	unsigned char   h_source[ETH_ALEN];
+	unsigned short  h_proto;
+};
+
+struct bpf_elf_map SEC("maps") tun_iface = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.size_key = sizeof(int),
+	.size_value = sizeof(int),
+	.pinning = PIN_GLOBAL_NS,
+	.max_elem = 1,
+};
+
+static __always_inline bool is_vip_addr(__be16 eth_proto, __be32 daddr)
+{
+	if (eth_proto == htons(ETH_P_IP))
+		return (_htonl(0xffffff00) & daddr) == _htonl(0x0a0a0100);
+	else if (eth_proto == htons(ETH_P_IPV6))
+		return (daddr == _htonl(0x2401face));
+
+	return false;
+}
+
+SEC("l2_to_iptun_ingress_forward")
+int _l2_to_iptun_ingress_forward(struct __sk_buff *skb)
+{
+	struct bpf_tunnel_key tkey = {};
+	void *data = (void *)(long)skb->data;
+	struct eth_hdr *eth = data;
+	void *data_end = (void *)(long)skb->data_end;
+	int key = 0, *ifindex;
+
+	int ret;
+
+	if (data + sizeof(*eth) > data_end)
+		return TC_ACT_OK;
+
+	ifindex = bpf_map_lookup_elem(&tun_iface, &key);
+	if (!ifindex)
+		return TC_ACT_OK;
+
+	if (eth->h_proto == htons(ETH_P_IP)) {
+		char fmt4[] = "ingress forward to ifindex:%d daddr4:%x\n";
+		struct iphdr *iph = data + sizeof(*eth);
+
+		if (data + sizeof(*eth) + sizeof(*iph) > data_end)
+			return TC_ACT_OK;
+
+		if (iph->protocol != IPPROTO_IPIP)
+			return TC_ACT_OK;
+
+		bpf_trace_printk(fmt4, sizeof(fmt4), *ifindex,
+				 _htonl(iph->daddr));
+		return bpf_redirect(*ifindex, BPF_F_INGRESS);
+	} else if (eth->h_proto == htons(ETH_P_IPV6)) {
+		char fmt6[] = "ingress forward to ifindex:%d daddr6:%x::%x\n";
+		struct ipv6hdr *ip6h = data + sizeof(*eth);
+
+		if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
+			return TC_ACT_OK;
+
+		if (ip6h->nexthdr != IPPROTO_IPIP &&
+		    ip6h->nexthdr != IPPROTO_IPV6)
+			return TC_ACT_OK;
+
+		bpf_trace_printk(fmt6, sizeof(fmt6), *ifindex,
+				 _htonl(ip6h->daddr.s6_addr32[0]),
+				 _htonl(ip6h->daddr.s6_addr32[3]));
+		return bpf_redirect(*ifindex, BPF_F_INGRESS);
+	}
+
+	return TC_ACT_OK;
+}
+
+SEC("l2_to_iptun_ingress_redirect")
+int _l2_to_iptun_ingress_redirect(struct __sk_buff *skb)
+{
+	struct bpf_tunnel_key tkey = {};
+	void *data = (void *)(long)skb->data;
+	struct eth_hdr *eth = data;
+	void *data_end = (void *)(long)skb->data_end;
+	int key = 0, *ifindex;
+
+	int ret;
+
+	if (data + sizeof(*eth) > data_end)
+		return TC_ACT_OK;
+
+	ifindex = bpf_map_lookup_elem(&tun_iface, &key);
+	if (!ifindex)
+		return TC_ACT_OK;
+
+	if (eth->h_proto == htons(ETH_P_IP)) {
+		char fmt4[] = "e/ingress redirect daddr4:%x to ifindex:%d\n";
+		struct iphdr *iph = data + sizeof(*eth);
+		__be32 daddr = iph->daddr;
+
+		if (data + sizeof(*eth) + sizeof(*iph) > data_end)
+			return TC_ACT_OK;
+
+		if (!is_vip_addr(eth->h_proto, daddr))
+			return TC_ACT_OK;
+
+		bpf_trace_printk(fmt4, sizeof(fmt4), _htonl(daddr), *ifindex);
+	} else {
+		return TC_ACT_OK;
+	}
+
+	tkey.tunnel_id = 10000;
+	tkey.tunnel_ttl = 64;
+	tkey.remote_ipv4 = 0x0a020166; /* 10.2.1.102 */
+	bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), 0);
+	return bpf_redirect(*ifindex, 0);
+}
+
+SEC("l2_to_ip6tun_ingress_redirect")
+int _l2_to_ip6tun_ingress_redirect(struct __sk_buff *skb)
+{
+	struct bpf_tunnel_key tkey = {};
+	void *data = (void *)(long)skb->data;
+	struct eth_hdr *eth = data;
+	void *data_end = (void *)(long)skb->data_end;
+	int key = 0, *ifindex;
+
+	if (data + sizeof(*eth) > data_end)
+		return TC_ACT_OK;
+
+	ifindex = bpf_map_lookup_elem(&tun_iface, &key);
+	if (!ifindex)
+		return TC_ACT_OK;
+
+	if (eth->h_proto == htons(ETH_P_IP)) {
+		char fmt4[] = "e/ingress redirect daddr4:%x to ifindex:%d\n";
+		struct iphdr *iph = data + sizeof(*eth);
+
+		if (data + sizeof(*eth) + sizeof(*iph) > data_end)
+			return TC_ACT_OK;
+
+		if (!is_vip_addr(eth->h_proto, iph->daddr))
+			return TC_ACT_OK;
+
+		bpf_trace_printk(fmt4, sizeof(fmt4), _htonl(iph->daddr),
+				 *ifindex);
+	} else if (eth->h_proto == htons(ETH_P_IPV6)) {
+		char fmt6[] = "e/ingress redirect daddr6:%x to ifindex:%d\n";
+		struct ipv6hdr *ip6h = data + sizeof(*eth);
+
+		if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
+			return TC_ACT_OK;
+
+		if (!is_vip_addr(eth->h_proto, ip6h->daddr.s6_addr32[0]))
+			return TC_ACT_OK;
+
+		bpf_trace_printk(fmt6, sizeof(fmt6),
+				 _htonl(ip6h->daddr.s6_addr32[0]), *ifindex);
+	} else {
+		return TC_ACT_OK;
+	}
+
+	tkey.tunnel_id = 10000;
+	tkey.tunnel_ttl = 64;
+	/* 2401:db02:0:0:0:0:0:66 */
+	tkey.remote_ipv6[0] = _htonl(0x2401db02);
+	tkey.remote_ipv6[1] = 0;
+	tkey.remote_ipv6[2] = 0;
+	tkey.remote_ipv6[3] = _htonl(0x00000066);
+	bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), BPF_F_TUNINFO_IPV6);
+	return bpf_redirect(*ifindex, 0);
+}
+
+SEC("drop_non_tun_vip")
+int _drop_non_tun_vip(struct __sk_buff *skb)
+{
+	struct bpf_tunnel_key tkey = {};
+	void *data = (void *)(long)skb->data;
+	struct eth_hdr *eth = data;
+	void *data_end = (void *)(long)skb->data_end;
+
+	if (data + sizeof(*eth) > data_end)
+		return TC_ACT_OK;
+
+	if (eth->h_proto == htons(ETH_P_IP)) {
+		struct iphdr *iph = data + sizeof(*eth);
+
+		if (data + sizeof(*eth) + sizeof(*iph) > data_end)
+			return TC_ACT_OK;
+
+		if (is_vip_addr(eth->h_proto, iph->daddr))
+			return TC_ACT_SHOT;
+	} else if (eth->h_proto == htons(ETH_P_IPV6)) {
+		struct ipv6hdr *ip6h = data + sizeof(*eth);
+
+		if (data + sizeof(*eth) + sizeof(*ip6h) > data_end)
+			return TC_ACT_OK;
+
+		if (is_vip_addr(eth->h_proto, ip6h->daddr.s6_addr32[0]))
+			return TC_ACT_SHOT;
+	}
+
+	return TC_ACT_OK;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/samples/bpf/tc_l2_redirect_user.c b/samples/bpf/tc_l2_redirect_user.c
new file mode 100644
index 0000000..4013c53
--- /dev/null
+++ b/samples/bpf/tc_l2_redirect_user.c
@@ -0,0 +1,73 @@
+/* Copyright (c) 2016 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <linux/unistd.h>
+#include <linux/bpf.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+#include "libbpf.h"
+
+static void usage(void)
+{
+	printf("Usage: tc_l2_ipip_redirect [...]\n");
+	printf("       -U <file>   Update an already pinned BPF array\n");
+	printf("       -i <ifindex> Interface index\n");
+	printf("       -h          Display this help\n");
+}
+
+int main(int argc, char **argv)
+{
+	const char *pinned_file = NULL;
+	int ifindex = -1;
+	int array_key = 0;
+	int array_fd = -1;
+	int ret = -1;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "F:U:i:")) != -1) {
+		switch (opt) {
+		/* General args */
+		case 'U':
+			pinned_file = optarg;
+			break;
+		case 'i':
+			ifindex = atoi(optarg);
+			break;
+		default:
+			usage();
+			goto out;
+		}
+	}
+
+	if (ifindex < 0 || !pinned_file) {
+		usage();
+		goto out;
+	}
+
+	array_fd = bpf_obj_get(pinned_file);
+	if (array_fd < 0) {
+		fprintf(stderr, "bpf_obj_get(%s): %s(%d)\n",
+			pinned_file, strerror(errno), errno);
+		goto out;
+	}
+
+	/* bpf_tunnel_key.remote_ipv4 expects host byte orders */
+	ret = bpf_update_elem(array_fd, &array_key, &ifindex, 0);
+	if (ret) {
+		perror("bpf_update_elem");
+		goto out;
+	}
+
+out:
+	if (array_fd != -1)
+		close(array_fd);
+	return ret;
+}