sample/bpf: Add xdp_redirect_map_multi for redirect_map broadcast test

This is a sample for xdp redirect broadcast. In the sample we could forward
all packets between given interfaces. There is also an option -X that could
enable 2nd xdp_prog on egress interface.

Signed-off-by: Hangbin Liu <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Acked-by: Toke Høiland-Jørgensen <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

samples/bpf/Makefile

···
 tprogs-y += per_socket_stats_example
 tprogs-y += xdp_redirect
 tprogs-y += xdp_redirect_map
+tprogs-y += xdp_redirect_map_multi
 tprogs-y += xdp_redirect_cpu
 tprogs-y += xdp_monitor
 tprogs-y += xdp_rxq_info
···
 per_socket_stats_example-objs := cookie_uid_helper_example.o
 xdp_redirect-objs := xdp_redirect_user.o
 xdp_redirect_map-objs := xdp_redirect_map_user.o
+xdp_redirect_map_multi-objs := xdp_redirect_map_multi_user.o
 xdp_redirect_cpu-objs := xdp_redirect_cpu_user.o
 xdp_monitor-objs := xdp_monitor_user.o
 xdp_rxq_info-objs := xdp_rxq_info_user.o
···
 always-y += tcp_dumpstats_kern.o
 always-y += xdp_redirect_kern.o
 always-y += xdp_redirect_map_kern.o
+always-y += xdp_redirect_map_multi_kern.o
 always-y += xdp_redirect_cpu_kern.o
 always-y += xdp_monitor_kern.o
 always-y += xdp_rxq_info_kern.o

samples/bpf/xdp_redirect_map_multi_kern.c

···
+// SPDX-License-Identifier: GPL-2.0
+#define KBUILD_MODNAME "foo"
+#include <uapi/linux/bpf.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_DEVMAP_HASH);
+	__uint(key_size, sizeof(int));
+	__uint(value_size, sizeof(int));
+	__uint(max_entries, 32);
+} forward_map_general SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_DEVMAP_HASH);
+	__uint(key_size, sizeof(int));
+	__uint(value_size, sizeof(struct bpf_devmap_val));
+	__uint(max_entries, 32);
+} forward_map_native SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__type(key, u32);
+	__type(value, long);
+	__uint(max_entries, 1);
+} rxcnt SEC(".maps");
+
+/* map to store egress interfaces mac addresses, set the
+ * max_entries to 1 and extend it in user sapce prog.
+ */
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, u32);
+	__type(value, __be64);
+	__uint(max_entries, 1);
+} mac_map SEC(".maps");
+
+static int xdp_redirect_map(struct xdp_md *ctx, void *forward_map)
+{
+	long *value;
+	u32 key = 0;
+
+	/* count packet in global counter */
+	value = bpf_map_lookup_elem(&rxcnt, &key);
+	if (value)
+		*value += 1;
+
+	return bpf_redirect_map(forward_map, key,
+				BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS);
+}
+
+SEC("xdp_redirect_general")
+int xdp_redirect_map_general(struct xdp_md *ctx)
+{
+	return xdp_redirect_map(ctx, &forward_map_general);
+}
+
+SEC("xdp_redirect_native")
+int xdp_redirect_map_native(struct xdp_md *ctx)
+{
+	return xdp_redirect_map(ctx, &forward_map_native);
+}
+
+SEC("xdp_devmap/map_prog")
+int xdp_devmap_prog(struct xdp_md *ctx)
+{
+	void *data_end = (void *)(long)ctx->data_end;
+	void *data = (void *)(long)ctx->data;
+	u32 key = ctx->egress_ifindex;
+	struct ethhdr *eth = data;
+	__be64 *mac;
+	u64 nh_off;
+
+	nh_off = sizeof(*eth);
+	if (data + nh_off > data_end)
+		return XDP_DROP;
+
+	mac = bpf_map_lookup_elem(&mac_map, &key);
+	if (mac)
+		__builtin_memcpy(eth->h_source, mac, ETH_ALEN);
+
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";

samples/bpf/xdp_redirect_map_multi_user.c

···
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <linux/if_link.h>
+#include <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <net/if.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <sys/resource.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include "bpf_util.h"
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#define MAX_IFACE_NUM 32
+
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static int ifaces[MAX_IFACE_NUM] = {};
+static int rxcnt_map_fd;
+
+static void int_exit(int sig)
+{
+	__u32 prog_id = 0;
+	int i;
+
+	for (i = 0; ifaces[i] > 0; i++) {
+		if (bpf_get_link_xdp_id(ifaces[i], &prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id)
+			bpf_set_link_xdp_fd(ifaces[i], -1, xdp_flags);
+	}
+
+	exit(0);
+}
+
+static void poll_stats(int interval)
+{
+	unsigned int nr_cpus = bpf_num_possible_cpus();
+	__u64 values[nr_cpus], prev[nr_cpus];
+
+	memset(prev, 0, sizeof(prev));
+
+	while (1) {
+		__u64 sum = 0;
+		__u32 key = 0;
+		int i;
+
+		sleep(interval);
+		assert(bpf_map_lookup_elem(rxcnt_map_fd, &key, values) == 0);
+		for (i = 0; i < nr_cpus; i++)
+			sum += (values[i] - prev[i]);
+		if (sum)
+			printf("Forwarding %10llu pkt/s\n", sum / interval);
+		memcpy(prev, values, sizeof(values));
+	}
+}
+
+static int get_mac_addr(unsigned int ifindex, void *mac_addr)
+{
+	char ifname[IF_NAMESIZE];
+	struct ifreq ifr;
+	int fd, ret = -1;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		return ret;
+
+	if (!if_indextoname(ifindex, ifname))
+		goto err_out;
+
+	strcpy(ifr.ifr_name, ifname);
+
+	if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0)
+		goto err_out;
+
+	memcpy(mac_addr, ifr.ifr_hwaddr.sa_data, 6 * sizeof(char));
+	ret = 0;
+
+err_out:
+	close(fd);
+	return ret;
+}
+
+static int update_mac_map(struct bpf_object *obj)
+{
+	int i, ret = -1, mac_map_fd;
+	unsigned char mac_addr[6];
+	unsigned int ifindex;
+
+	mac_map_fd = bpf_object__find_map_fd_by_name(obj, "mac_map");
+	if (mac_map_fd < 0) {
+		printf("find mac map fd failed\n");
+		return ret;
+	}
+
+	for (i = 0; ifaces[i] > 0; i++) {
+		ifindex = ifaces[i];
+
+		ret = get_mac_addr(ifindex, mac_addr);
+		if (ret < 0) {
+			printf("get interface %d mac failed\n", ifindex);
+			return ret;
+		}
+
+		ret = bpf_map_update_elem(mac_map_fd, &ifindex, mac_addr, 0);
+		if (ret) {
+			perror("bpf_update_elem mac_map_fd");
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void usage(const char *prog)
+{
+	fprintf(stderr,
+		"usage: %s [OPTS] <IFNAME|IFINDEX> <IFNAME|IFINDEX> ...\n"
+		"OPTS:\n"
+		"    -S    use skb-mode\n"
+		"    -N    enforce native mode\n"
+		"    -F    force loading prog\n"
+		"    -X    load xdp program on egress\n",
+		prog);
+}
+
+int main(int argc, char **argv)
+{
+	int i, ret, opt, forward_map_fd, max_ifindex = 0;
+	struct bpf_program *ingress_prog, *egress_prog;
+	int ingress_prog_fd, egress_prog_fd = 0;
+	struct bpf_devmap_val devmap_val;
+	bool attach_egress_prog = false;
+	char ifname[IF_NAMESIZE];
+	struct bpf_map *mac_map;
+	struct bpf_object *obj;
+	unsigned int ifindex;
+	char filename[256];
+
+	while ((opt = getopt(argc, argv, "SNFX")) != -1) {
+		switch (opt) {
+		case 'S':
+			xdp_flags |= XDP_FLAGS_SKB_MODE;
+			break;
+		case 'N':
+			/* default, set below */
+			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
+		case 'X':
+			attach_egress_prog = true;
+			break;
+		default:
+			usage(basename(argv[0]));
+			return 1;
+		}
+	}
+
+	if (!(xdp_flags & XDP_FLAGS_SKB_MODE)) {
+		xdp_flags |= XDP_FLAGS_DRV_MODE;
+	} else if (attach_egress_prog) {
+		printf("Load xdp program on egress with SKB mode not supported yet\n");
+		return 1;
+	}
+
+	if (optind == argc) {
+		printf("usage: %s <IFNAME|IFINDEX> <IFNAME|IFINDEX> ...\n", argv[0]);
+		return 1;
+	}
+
+	printf("Get interfaces");
+	for (i = 0; i < MAX_IFACE_NUM && argv[optind + i]; i++) {
+		ifaces[i] = if_nametoindex(argv[optind + i]);
+		if (!ifaces[i])
+			ifaces[i] = strtoul(argv[optind + i], NULL, 0);
+		if (!if_indextoname(ifaces[i], ifname)) {
+			perror("Invalid interface name or i");
+			return 1;
+		}
+
+		/* Find the largest index number */
+		if (ifaces[i] > max_ifindex)
+			max_ifindex = ifaces[i];
+
+		printf(" %d", ifaces[i]);
+	}
+	printf("\n");
+
+	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+	obj = bpf_object__open(filename);
+	if (libbpf_get_error(obj)) {
+		printf("ERROR: opening BPF object file failed\n");
+		obj = NULL;
+		goto err_out;
+	}
+
+	/* Reset the map size to max ifindex + 1 */
+	if (attach_egress_prog) {
+		mac_map = bpf_object__find_map_by_name(obj, "mac_map");
+		ret = bpf_map__resize(mac_map, max_ifindex + 1);
+		if (ret < 0) {
+			printf("ERROR: reset mac map size failed\n");
+			goto err_out;
+		}
+	}
+
+	/* load BPF program */
+	if (bpf_object__load(obj)) {
+		printf("ERROR: loading BPF object file failed\n");
+		goto err_out;
+	}
+
+	if (xdp_flags & XDP_FLAGS_SKB_MODE) {
+		ingress_prog = bpf_object__find_program_by_name(obj, "xdp_redirect_map_general");
+		forward_map_fd = bpf_object__find_map_fd_by_name(obj, "forward_map_general");
+	} else {
+		ingress_prog = bpf_object__find_program_by_name(obj, "xdp_redirect_map_native");
+		forward_map_fd = bpf_object__find_map_fd_by_name(obj, "forward_map_native");
+	}
+	if (!ingress_prog || forward_map_fd < 0) {
+		printf("finding ingress_prog/forward_map in obj file failed\n");
+		goto err_out;
+	}
+
+	ingress_prog_fd = bpf_program__fd(ingress_prog);
+	if (ingress_prog_fd < 0) {
+		printf("find ingress_prog fd failed\n");
+		goto err_out;
+	}
+
+	rxcnt_map_fd = bpf_object__find_map_fd_by_name(obj, "rxcnt");
+	if (rxcnt_map_fd < 0) {
+		printf("bpf_object__find_map_fd_by_name failed\n");
+		goto err_out;
+	}
+
+	if (attach_egress_prog) {
+		/* Update mac_map with all egress interfaces' mac addr */
+		if (update_mac_map(obj) < 0) {
+			printf("Error: update mac map failed");
+			goto err_out;
+		}
+
+		/* Find egress prog fd */
+		egress_prog = bpf_object__find_program_by_name(obj, "xdp_devmap_prog");
+		if (!egress_prog) {
+			printf("finding egress_prog in obj file failed\n");
+			goto err_out;
+		}
+		egress_prog_fd = bpf_program__fd(egress_prog);
+		if (egress_prog_fd < 0) {
+			printf("find egress_prog fd failed\n");
+			goto err_out;
+		}
+	}
+
+	/* Remove attached program when program is interrupted or killed */
+	signal(SIGINT, int_exit);
+	signal(SIGTERM, int_exit);
+
+	/* Init forward multicast groups */
+	for (i = 0; ifaces[i] > 0; i++) {
+		ifindex = ifaces[i];
+
+		/* bind prog_fd to each interface */
+		ret = bpf_set_link_xdp_fd(ifindex, ingress_prog_fd, xdp_flags);
+		if (ret) {
+			printf("Set xdp fd failed on %d\n", ifindex);
+			goto err_out;
+		}
+
+		/* Add all the interfaces to forward group and attach
+		 * egress devmap programe if exist
+		 */
+		devmap_val.ifindex = ifindex;
+		devmap_val.bpf_prog.fd = egress_prog_fd;
+		ret = bpf_map_update_elem(forward_map_fd, &ifindex, &devmap_val, 0);
+		if (ret) {
+			perror("bpf_map_update_elem forward_map");
+			goto err_out;
+		}
+	}
+
+	poll_stats(2);
+
+	return 0;
+
+err_out:
+	return 1;
+}