[bpf-next,8/8] samples/bpf: Add xdp_trafficgen sample

Commit Message

Toke Høiland-Jørgensen Dec. 2, 2021, 12:02 a.m. UTC

This adds an XDP-based traffic generator sample which uses the DO_REDIRECT
flag of bpf_prog_run(). It works by building the initial packet in
userspace and passing it to the kernel where an XDP program redirects the
packet to the target interface. The traffic generator supports two modes of
operation: one that just sends copies of the same packet as fast as it can
without touching the packet data at all, and one that rewrites the
destination port number of each packet, making the generated traffic span a
range of port numbers.

The dynamic mode is included to demonstrate how the bpf_prog_run() facility
enables building a completely programmable packet generator using XDP.
Using the dynamic mode has about a 10% overhead compared to the static
mode, because the latter completely avoids touching the page data.

Signed-off-by: Toke Høiland-Jørgensen <[e-mail]>
---
 samples/bpf/.gitignore            |   1 +
 samples/bpf/Makefile              |   4 +
 samples/bpf/xdp_redirect.bpf.c    |  34 +++
 samples/bpf/xdp_trafficgen_user.c | 444 ++++++++++++++++++++++++++++++
 4 files changed, 483 insertions(+)
 create mode 100644 samples/bpf/xdp_trafficgen_user.c

Patch

diff --git a/samples/bpf/.gitignore b/samples/bpf/.gitignore
index 0e7bfdbff80a..935672cbdd80 100644
--- a/samples/bpf/.gitignore
+++ b/samples/bpf/.gitignore
@@ -49,6 +49,7 @@  xdp_redirect_map_multi
 xdp_router_ipv4
 xdp_rxq_info
 xdp_sample_pkts
+xdp_trafficgen
 xdp_tx_iptunnel
 xdpsock
 xdpsock_ctrl_proc
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index a886dff1ba89..590a09c8e7a5 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -58,6 +58,7 @@  tprogs-y += xdp_redirect_cpu
 tprogs-y += xdp_redirect_map_multi
 tprogs-y += xdp_redirect_map
 tprogs-y += xdp_redirect
+tprogs-y += xdp_trafficgen
 tprogs-y += xdp_monitor
 
 # Libbpf dependencies
@@ -123,6 +124,7 @@  xdp_redirect_map_multi-objs := xdp_redirect_map_multi_user.o $(XDP_SAMPLE)
 xdp_redirect_cpu-objs := xdp_redirect_cpu_user.o $(XDP_SAMPLE)
 xdp_redirect_map-objs := xdp_redirect_map_user.o $(XDP_SAMPLE)
 xdp_redirect-objs := xdp_redirect_user.o $(XDP_SAMPLE)
+xdp_trafficgen-objs := xdp_trafficgen_user.o $(XDP_SAMPLE)
 xdp_monitor-objs := xdp_monitor_user.o $(XDP_SAMPLE)
 
 # Tell kbuild to always build the programs
@@ -221,6 +223,7 @@  TPROGLDLIBS_map_perf_test	+= -lrt
 TPROGLDLIBS_test_overhead	+= -lrt
 TPROGLDLIBS_xdpsock		+= -pthread -lcap
 TPROGLDLIBS_xsk_fwd		+= -pthread
+TPROGLDLIBS_xdp_trafficgen	+= -pthread
 
 # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
 # make M=samples/bpf LLC=~/git/llvm-project/llvm/build/bin/llc CLANG=~/git/llvm-project/llvm/build/bin/clang
@@ -336,6 +339,7 @@  $(obj)/xdp_redirect_cpu_user.o: $(obj)/xdp_redirect_cpu.skel.h
 $(obj)/xdp_redirect_map_multi_user.o: $(obj)/xdp_redirect_map_multi.skel.h
 $(obj)/xdp_redirect_map_user.o: $(obj)/xdp_redirect_map.skel.h
 $(obj)/xdp_redirect_user.o: $(obj)/xdp_redirect.skel.h
+$(obj)/xdp_trafficgen_user.o: $(obj)/xdp_redirect.skel.h
 $(obj)/xdp_monitor_user.o: $(obj)/xdp_monitor.skel.h
 
 $(obj)/tracex5_kern.o: $(obj)/syscall_nrs.h
diff --git a/samples/bpf/xdp_redirect.bpf.c b/samples/bpf/xdp_redirect.bpf.c
index 7c02bacfe96b..a09c6f576b79 100644
--- a/samples/bpf/xdp_redirect.bpf.c
+++ b/samples/bpf/xdp_redirect.bpf.c
@@ -39,6 +39,40 @@  int xdp_redirect_prog(struct xdp_md *ctx)
 	return bpf_redirect(ifindex_out, 0);
 }
 
+SEC("xdp")
+int xdp_redirect_notouch(struct xdp_md *ctx)
+{
+	return bpf_redirect(ifindex_out, 0);
+}
+
+const volatile __u16 port_start;
+const volatile __u16 port_range;
+volatile __u16 next_port = 0;
+
+SEC("xdp")
+int xdp_redirect_update_port(struct xdp_md *ctx)
+{
+	void *data_end = (void *)(long)ctx->data_end;
+	void *data = (void *)(long)ctx->data;
+	__u16 cur_port, cksum_diff;
+	struct udphdr *hdr;
+
+	hdr = data + (sizeof(struct ethhdr) + sizeof(struct ipv6hdr));
+	if (hdr + 1 > data_end)
+		return XDP_ABORTED;
+
+	cur_port = bpf_ntohs(hdr->dest);
+	cksum_diff = next_port - cur_port;
+	if (cksum_diff) {
+		hdr->check = bpf_htons(~(~bpf_ntohs(hdr->check) + cksum_diff));
+		hdr->dest = bpf_htons(next_port);
+	}
+	if (next_port++ >= port_start + port_range - 1)
+		next_port = port_start;
+
+	return bpf_redirect(ifindex_out, 0);
+}
+
 /* Redirect require an XDP bpf_prog loaded on the TX device */
 SEC("xdp")
 int xdp_redirect_dummy_prog(struct xdp_md *ctx)
diff --git a/samples/bpf/xdp_trafficgen_user.c b/samples/bpf/xdp_trafficgen_user.c
new file mode 100644
index 000000000000..92e09ee385c7
--- /dev/null
+++ b/samples/bpf/xdp_trafficgen_user.c
@@ -0,0 +1,444 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2021 Toke Høiland-Jørgensen <[e-mail]>
+ */
+static const char *__doc__ =
+"XDP trafficgen tool, using bpf_redirect helper\n"
+"Usage: xdp_trafficgen [options] <IFINDEX|IFNAME>_OUT\n";
+
+#define _GNU_SOURCE
+#include <linux/bpf.h>
+#include <linux/if_link.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/ipv6.h>
+#include <linux/in6.h>
+#include <linux/udp.h>
+#include <assert.h>
+#include <errno.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <net/if.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <limits.h>
+#include <getopt.h>
+#include <pthread.h>
+#include <arpa/inet.h>
+#include <netinet/ether.h>
+#include <sys/resource.h>
+#include <sys/ioctl.h>
+#include <bpf/bpf.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/libbpf.h>
+#include "bpf_util.h"
+#include "xdp_sample_user.h"
+#include "xdp_redirect.skel.h"
+
+static int mask = SAMPLE_REDIRECT_ERR_CNT |
+		  SAMPLE_EXCEPTION_CNT | SAMPLE_DEVMAP_XMIT_CNT_MULTI;
+
+DEFINE_SAMPLE_INIT(xdp_redirect);
+
+static const struct option long_options[] = {
+	{"dst-mac",	required_argument,	NULL, 'm' },
+	{"src-mac",	required_argument,	NULL, 'M' },
+	{"dst-ip",	required_argument,	NULL, 'a' },
+	{"src-ip",	required_argument,	NULL, 'A' },
+	{"dst-port",	required_argument,	NULL, 'p' },
+	{"src-port",	required_argument,	NULL, 'P' },
+	{"dynamic-ports", required_argument,	NULL, 'd' },
+	{"help",	no_argument,		NULL, 'h' },
+	{"stats",	no_argument,		NULL, 's' },
+	{"interval",	required_argument,	NULL, 'i' },
+	{"n-pkts",	required_argument,	NULL, 'n' },
+	{"threads",	required_argument,	NULL, 't' },
+	{"verbose",	no_argument,		NULL, 'v' },
+	{}
+};
+
+static int sample_res;
+static bool sample_exited;
+
+static void *run_samples(void *arg)
+{
+	unsigned long *interval = arg;
+
+	sample_res = sample_run(*interval, NULL, NULL);
+	sample_exited = true;
+	return NULL;
+}
+
+struct ipv6_packet {
+	struct ethhdr eth;
+	struct ipv6hdr iph;
+	struct udphdr udp;
+	__u8 payload[64 - sizeof(struct udphdr)
+		     - sizeof(struct ethhdr) - sizeof(struct ipv6hdr)];
+} __packed;
+static struct ipv6_packet pkt_v6 = {
+	.eth.h_proto = __bpf_constant_htons(ETH_P_IPV6),
+	.iph.version = 6,
+	.iph.nexthdr = IPPROTO_UDP,
+	.iph.payload_len = bpf_htons(sizeof(struct ipv6_packet)
+				     - offsetof(struct ipv6_packet, udp)),
+	.iph.hop_limit = 1,
+	.iph.saddr.s6_addr16 = {bpf_htons(0xfe80), 0, 0, 0, 0, 0, 0, bpf_htons(1)},
+	.iph.daddr.s6_addr16 = {bpf_htons(0xfe80), 0, 0, 0, 0, 0, 0, bpf_htons(2)},
+	.udp.source = bpf_htons(1),
+	.udp.dest = bpf_htons(1),
+	.udp.len = bpf_htons(sizeof(struct ipv6_packet)
+			     - offsetof(struct ipv6_packet, udp)),
+};
+
+struct thread_config {
+	void *pkt;
+	size_t pkt_size;
+	__u32 cpu_core_id;
+	__u32 num_pkts;
+	int prog_fd;
+};
+
+struct config {
+	__be64 src_mac;
+	__be64 dst_mac;
+	struct in6_addr src_ip;
+	struct in6_addr dst_ip;
+	__be16 src_port;
+	__be16 dst_port;
+	int ifindex;
+	char ifname[IFNAMSIZ];
+};
+
+/* Get the mac address of the interface given interface name */
+static __be64 getmac(char *iface)
+{
+	struct ifreq ifr;
+	__be64 mac = 0;
+	int fd, i;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		return -1;
+	ifr.ifr_addr.sa_family = AF_INET;
+	memcpy(&ifr.ifr_name, iface, IFNAMSIZ);
+	if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
+		fprintf(stderr, "ioctl failed leaving....\n");
+		close(fd);
+		return -1;
+	}
+	for (i = 0; i < 6 ; i++)
+		*((__u8 *)&mac + i) = (__u8)ifr.ifr_hwaddr.sa_data[i];
+	close(fd);
+	return mac;
+}
+
+static void *run_traffic(void *arg)
+{
+	const struct thread_config *cfg = arg;
+	struct xdp_md ctx_in = {
+		.data_end = cfg->pkt_size,
+	};
+	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
+			    .data_in = cfg->pkt,
+			    .data_size_in = cfg->pkt_size,
+			    .ctx_in = &ctx_in,
+			    .ctx_size_in = sizeof(ctx_in),
+			    .repeat = cfg->num_pkts ?: 1 << 24,
+			    .flags = BPF_F_TEST_XDP_DO_REDIRECT,
+		);
+	__u64 iterations = 0;
+	cpu_set_t cpu_cores;
+	int err;
+
+	CPU_ZERO(&cpu_cores);
+	CPU_SET(cfg->cpu_core_id, &cpu_cores);
+	pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpu_cores);
+	do {
+		err = bpf_prog_test_run_opts(cfg->prog_fd, &opts);
+		if (err) {
+			printf("bpf_prog_test_run ret %d errno %d\n", err, errno);
+			break;
+		}
+		iterations += opts.repeat;
+	} while (!sample_exited && (!cfg->num_pkts || cfg->num_pkts < iterations));
+	return NULL;
+}
+
+static __be16 calc_udp_cksum(const struct ipv6_packet *pkt)
+{
+	__u32 chksum = pkt->iph.nexthdr + bpf_ntohs(pkt->iph.payload_len);
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		chksum += bpf_ntohs(pkt->iph.saddr.s6_addr16[i]);
+		chksum += bpf_ntohs(pkt->iph.daddr.s6_addr16[i]);
+	}
+	chksum += bpf_ntohs(pkt->udp.source);
+	chksum += bpf_ntohs(pkt->udp.dest);
+	chksum += bpf_ntohs(pkt->udp.len);
+
+	while (chksum >> 16)
+		chksum = (chksum & 0xFFFF) + (chksum >> 16);
+	return bpf_htons(~chksum);
+}
+
+static int prepare_pkt(struct config *cfg)
+{
+	__be64 src_mac = cfg->src_mac;
+	struct in6_addr nulladdr = {};
+	int i;
+
+	if (!src_mac) {
+		src_mac = getmac(cfg->ifname);
+		if (src_mac == -1)
+			return -1;
+	}
+	for (i = 0; i < 6 ; i++) {
+		pkt_v6.eth.h_source[i] = *((__u8 *)&src_mac + i);
+		if (cfg->dst_mac)
+			pkt_v6.eth.h_dest[i] = *((__u8 *)&cfg->dst_mac + i);
+	}
+	if (memcmp(&cfg->src_ip, &nulladdr, sizeof(nulladdr)))
+		pkt_v6.iph.saddr = cfg->src_ip;
+	if (memcmp(&cfg->dst_ip, &nulladdr, sizeof(nulladdr)))
+		pkt_v6.iph.daddr = cfg->dst_ip;
+	if (cfg->src_port)
+		pkt_v6.udp.source = cfg->src_port;
+	if (cfg->dst_port)
+		pkt_v6.udp.dest = cfg->dst_port;
+	pkt_v6.udp.check = calc_udp_cksum(&pkt_v6);
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	unsigned long interval = 2, threads = 1, dynports = 0;
+	__u64 num_pkts = 0;
+	pthread_t sample_thread, *runner_threads = NULL;
+	struct thread_config *t = NULL, tcfg = {
+		.pkt = &pkt_v6,
+		.pkt_size = sizeof(pkt_v6),
+	};
+	int ret = EXIT_FAIL_OPTION;
+	struct xdp_redirect *skel;
+	struct config cfg = {};
+	bool error = true;
+	int opt, i, err;
+
+	while ((opt = getopt_long(argc, argv, "a:A:d:hi:m:M:n:p:P:t:vs",
+				  long_options, NULL)) != -1) {
+		switch (opt) {
+		case 'a':
+			if (!inet_pton(AF_INET6, optarg, &cfg.dst_ip)) {
+				fprintf(stderr, "Invalid IPv6 address: %s\n", optarg);
+				return -1;
+			}
+			break;
+		case 'A':
+			if (!inet_pton(AF_INET6, optarg, &cfg.src_ip)) {
+				fprintf(stderr, "Invalid IPv6 address: %s\n", optarg);
+				return -1;
+			}
+			break;
+		case 'd':
+			dynports = strtoul(optarg, NULL, 0);
+			if (dynports < 2 || dynports >= 65535) {
+				fprintf(stderr, "Dynamic port range must be >1 and < 65535\n");
+				return -1;
+			}
+			break;
+		case 'i':
+			interval = strtoul(optarg, NULL, 0);
+			if (interval < 1 || interval == ULONG_MAX) {
+				fprintf(stderr, "Need non-zero interval\n");
+				return -1;
+			}
+			break;
+		case 't':
+			threads = strtoul(optarg, NULL, 0);
+			if (threads < 1 || threads == ULONG_MAX) {
+				fprintf(stderr, "Need at least 1 thread\n");
+				return -1;
+			}
+			break;
+		case 'm':
+		case 'M':
+			struct ether_addr *a;
+
+			a = ether_aton(optarg);
+			if (!a) {
+				fprintf(stderr, "Invalid MAC: %s\n", optarg);
+				return -1;
+			}
+			if (opt == 'm')
+				memcpy(&cfg.dst_mac, a, sizeof(*a));
+			else
+				memcpy(&cfg.src_mac, a, sizeof(*a));
+			break;
+		case 'n':
+			num_pkts = strtoull(optarg, NULL, 0);
+			if (num_pkts >= 1ULL << 32) {
+				fprintf(stderr, "Can send up to 2^32-1 pkts or infinite (0)\n");
+				return -1;
+			}
+			tcfg.num_pkts = num_pkts;
+			break;
+		case 'p':
+		case 'P':
+			unsigned long p;
+
+			p = strtoul(optarg, NULL, 0);
+			if (!p || p > 0xFFFF) {
+				fprintf(stderr, "Invalid port: %s\n", optarg);
+				return -1;
+			}
+			if (opt == 'p')
+				cfg.dst_port = bpf_htons(p);
+			else
+				cfg.src_port = bpf_htons(p);
+			break;
+		case 'v':
+			sample_switch_mode();
+			break;
+		case 's':
+			mask |= SAMPLE_REDIRECT_CNT;
+			break;
+		case 'h':
+			error = false;
+		default:
+			sample_usage(argv, long_options, __doc__, mask, error);
+			return ret;
+		}
+	}
+
+	if (argc <= optind) {
+		sample_usage(argv, long_options, __doc__, mask, true);
+		return ret;
+	}
+
+	cfg.ifindex = if_nametoindex(argv[optind]);
+	if (!cfg.ifindex)
+		cfg.ifindex = strtoul(argv[optind], NULL, 0);
+
+	if (!cfg.ifindex) {
+		fprintf(stderr, "Bad interface index or name\n");
+		sample_usage(argv, long_options, __doc__, mask, true);
+		goto end;
+	}
+
+	if (!if_indextoname(cfg.ifindex, cfg.ifname)) {
+		fprintf(stderr, "Failed to if_indextoname for %d: %s\n", cfg.ifindex,
+			strerror(errno));
+		goto end;
+	}
+
+	err = prepare_pkt(&cfg);
+	if (err)
+		goto end;
+
+	if (dynports) {
+		if (!cfg.dst_port) {
+			fprintf(stderr, "Must specify dst port when using dynamic port range\n");
+			goto end;
+		}
+
+		if (dynports + bpf_ntohs(cfg.dst_port) - 1 > 65535) {
+			fprintf(stderr, "Dynamic port range must end <= 65535\n");
+			goto end;
+		}
+	}
+
+	skel = xdp_redirect__open();
+	if (!skel) {
+		fprintf(stderr, "Failed to xdp_redirect__open: %s\n", strerror(errno));
+		ret = EXIT_FAIL_BPF;
+		goto end;
+	}
+
+	ret = sample_init_pre_load(skel);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to sample_init_pre_load: %s\n", strerror(-ret));
+		ret = EXIT_FAIL_BPF;
+		goto end_destroy;
+	}
+
+	skel->rodata->to_match[0] = cfg.ifindex;
+	skel->rodata->ifindex_out = cfg.ifindex;
+	skel->rodata->port_start = bpf_ntohs(cfg.dst_port);
+	skel->rodata->port_range = dynports;
+	skel->bss->next_port = bpf_ntohs(cfg.dst_port);
+
+	ret = xdp_redirect__load(skel);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to xdp_redirect__load: %s\n", strerror(errno));
+		ret = EXIT_FAIL_BPF;
+		goto end_destroy;
+	}
+
+	if (dynports)
+		tcfg.prog_fd = bpf_program__fd(skel->progs.xdp_redirect_update_port);
+	else
+		tcfg.prog_fd = bpf_program__fd(skel->progs.xdp_redirect_notouch);
+
+	ret = sample_init(skel, mask);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to initialize sample: %s\n", strerror(-ret));
+		ret = EXIT_FAIL;
+		goto end_destroy;
+	}
+
+	ret = EXIT_FAIL;
+
+	runner_threads = calloc(sizeof(pthread_t), threads);
+	if (!runner_threads) {
+		fprintf(stderr, "Couldn't allocate memory\n");
+		goto end_destroy;
+	}
+	t = calloc(sizeof(struct thread_config), threads);
+	if (!t) {
+		fprintf(stderr, "Couldn't allocate memory\n");
+		goto end_destroy;
+	}
+
+	printf("Transmitting on %s (ifindex %d; driver %s)\n",
+	       cfg.ifname, cfg.ifindex, get_driver_name(cfg.ifindex));
+
+	sample_exited = false;
+	ret = pthread_create(&sample_thread, NULL, run_samples, &interval);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to create sample thread: %s\n", strerror(-ret));
+		goto end_destroy;
+	}
+	sleep(1);
+	for (i = 0; i < threads; i++) {
+		memcpy(&t[i], &tcfg, sizeof(tcfg));
+		tcfg.cpu_core_id++;
+
+		ret = pthread_create(&runner_threads[i], NULL, run_traffic, &t[i]);
+		if (ret < 0) {
+			fprintf(stderr, "Failed to create traffic thread: %s\n", strerror(-ret));
+			ret = EXIT_FAIL;
+			goto end_cancel;
+		}
+	}
+	pthread_join(sample_thread, NULL);
+	for (i = 0; i < 0; i++)
+		pthread_join(runner_threads[i], NULL);
+	ret = sample_res;
+	goto end_destroy;
+
+end_cancel:
+	pthread_cancel(sample_thread);
+	for (i = 0; i < 0; i++)
+		pthread_cancel(runner_threads[i]);
+end_destroy:
+	xdp_redirect__destroy(skel);
+	free(runner_threads);
+	free(t);
+end:
+	sample_exit(ret);
+}