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xdp: bpf redirect with map sample program
Signed-off-by: John Fastabend <[email protected]> Tested-by: Andy Gospodarek <[email protected]> Acked-by: Daniel Borkmann <[email protected]> Acked-by: Jesper Dangaard Brouer <[email protected]> Signed-off-by: David S. Miller <[email protected]>
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‎samples/bpf/Makefile

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Original file line numberDiff line numberDiff line change
@@ -38,6 +38,7 @@ hostprogs-y += test_map_in_map
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hostprogs-y += per_socket_stats_example
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hostprogs-y += load_sock_ops
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hostprogs-y += xdp_redirect
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hostprogs-y += xdp_redirect_map
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# Libbpf dependencies
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LIBBPF := ../../tools/lib/bpf/bpf.o
@@ -80,6 +81,7 @@ xdp_tx_iptunnel-objs := bpf_load.o $(LIBBPF) xdp_tx_iptunnel_user.o
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test_map_in_map-objs := bpf_load.o $(LIBBPF) test_map_in_map_user.o
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per_socket_stats_example-objs := $(LIBBPF) cookie_uid_helper_example.o
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xdp_redirect-objs := bpf_load.o $(LIBBPF) xdp_redirect_user.o
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xdp_redirect_map-objs := bpf_load.o $(LIBBPF) xdp_redirect_map_user.o
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# Tell kbuild to always build the programs
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always := $(hostprogs-y)
@@ -122,6 +124,7 @@ always += tcp_cong_kern.o
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always += tcp_iw_kern.o
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always += tcp_clamp_kern.o
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always += xdp_redirect_kern.o
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always += xdp_redirect_map_kern.o
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126129
HOSTCFLAGS += -I$(objtree)/usr/include
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HOSTCFLAGS += -I$(srctree)/tools/lib/
@@ -159,6 +162,7 @@ HOSTLOADLIBES_lwt_len_hist += -l elf
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HOSTLOADLIBES_xdp_tx_iptunnel += -lelf
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HOSTLOADLIBES_test_map_in_map += -lelf
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HOSTLOADLIBES_xdp_redirect += -lelf
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HOSTLOADLIBES_xdp_redirect_map += -lelf
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# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
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# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang

‎samples/bpf/xdp_redirect_map_kern.c

Lines changed: 83 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,83 @@
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/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#define KBUILD_MODNAME "foo"
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#include <uapi/linux/bpf.h>
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#include <linux/in.h>
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#include <linux/if_ether.h>
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#include <linux/if_packet.h>
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#include <linux/if_vlan.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include "bpf_helpers.h"
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struct bpf_map_def SEC("maps") tx_port = {
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.type = BPF_MAP_TYPE_DEVMAP,
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.key_size = sizeof(int),
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.value_size = sizeof(int),
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.max_entries = 100,
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};
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struct bpf_map_def SEC("maps") rxcnt = {
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(long),
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.max_entries = 1,
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};
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static void swap_src_dst_mac(void *data)
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{
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unsigned short *p = data;
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unsigned short dst[3];
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dst[0] = p[0];
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dst[1] = p[1];
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dst[2] = p[2];
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p[0] = p[3];
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p[1] = p[4];
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p[2] = p[5];
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p[3] = dst[0];
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p[4] = dst[1];
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p[5] = dst[2];
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}
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SEC("xdp_redirect_map")
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int xdp_redirect_map_prog(struct xdp_md *ctx)
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{
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void *data_end = (void *)(long)ctx->data_end;
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void *data = (void *)(long)ctx->data;
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struct ethhdr *eth = data;
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int rc = XDP_DROP;
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int vport, port = 0, m = 0;
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long *value;
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u32 key = 0;
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u64 nh_off;
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nh_off = sizeof(*eth);
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if (data + nh_off > data_end)
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return rc;
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/* constant virtual port */
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vport = 0;
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/* count packet in global counter */
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value = bpf_map_lookup_elem(&rxcnt, &key);
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if (value)
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*value += 1;
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swap_src_dst_mac(data);
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/* send packet out physical port */
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return bpf_redirect_map(&tx_port, vport, 0);
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}
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83+
char _license[] SEC("license") = "GPL";

‎samples/bpf/xdp_redirect_map_user.c

Lines changed: 105 additions & 0 deletions
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@@ -0,0 +1,105 @@
1+
/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
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*
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* This program is free software; you can redistribute it and/or
4+
* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/bpf.h>
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#include <assert.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "bpf_load.h"
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#include "bpf_util.h"
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#include "libbpf.h"
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static int ifindex_in;
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static int ifindex_out;
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28+
static void int_exit(int sig)
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{
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set_link_xdp_fd(ifindex_in, -1, 0);
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exit(0);
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}
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/* simple per-protocol drop counter
35+
*/
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static void poll_stats(int interval, int ifindex)
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{
38+
unsigned int nr_cpus = bpf_num_possible_cpus();
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__u64 values[nr_cpus], prev[nr_cpus];
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41+
memset(prev, 0, sizeof(prev));
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while (1) {
44+
__u64 sum = 0;
45+
__u32 key = 0;
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int i;
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48+
sleep(interval);
49+
assert(bpf_map_lookup_elem(map_fd[1], &key, values) == 0);
50+
for (i = 0; i < nr_cpus; i++)
51+
sum += (values[i] - prev[i]);
52+
if (sum)
53+
printf("ifindex %i: %10llu pkt/s\n",
54+
ifindex, sum / interval);
55+
memcpy(prev, values, sizeof(values));
56+
}
57+
}
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59+
int main(int ac, char **argv)
60+
{
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char filename[256];
62+
int ret, key = 0;
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64+
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
65+
66+
if (ac != 3) {
67+
printf("usage: %s IFINDEX_IN IFINDEX_OUT\n", argv[0]);
68+
return 1;
69+
}
70+
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ifindex_in = strtoul(argv[1], NULL, 0);
72+
ifindex_out = strtoul(argv[2], NULL, 0);
73+
74+
if (load_bpf_file(filename)) {
75+
printf("%s", bpf_log_buf);
76+
return 1;
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}
78+
79+
if (!prog_fd[0]) {
80+
printf("load_bpf_file: %s\n", strerror(errno));
81+
return 1;
82+
}
83+
84+
signal(SIGINT, int_exit);
85+
86+
if (set_link_xdp_fd(ifindex_in, prog_fd[0], 0) < 0) {
87+
printf("link set xdp fd failed\n");
88+
return 1;
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}
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91+
printf("map[0] (vports) = %i, map[1] (map) = %i, map[2] (count) = %i\n",
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map_fd[0], map_fd[1], map_fd[2]);
93+
94+
/* populate virtual to physical port map */
95+
ret = bpf_map_update_elem(map_fd[0], &key, &ifindex_out, 0);
96+
if (ret) {
97+
perror("bpf_update_elem");
98+
goto out;
99+
}
100+
101+
poll_stats(2, ifindex_out);
102+
103+
out:
104+
return 0;
105+
}

‎tools/testing/selftests/bpf/bpf_helpers.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,8 @@ static int (*bpf_clone_redirect)(void *ctx, int ifindex, int flags) =
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(void *) BPF_FUNC_clone_redirect;
3939
static int (*bpf_redirect)(int ifindex, int flags) =
4040
(void *) BPF_FUNC_redirect;
41+
static int (*bpf_redirect_map)(void *map, int key, int flags) =
42+
(void *) BPF_FUNC_redirect_map;
4143
static int (*bpf_perf_event_output)(void *ctx, void *map,
4244
unsigned long long flags, void *data,
4345
int size) =

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