bpf: Test BPF_PROG_TYPE_SK_REUSEPORT

This patch add tests for the new BPF_PROG_TYPE_SK_REUSEPORT.

The tests cover:
- IPv4/IPv6 + TCP/UDP
- TCP syncookie
- TCP fastopen
- Cases when the bpf_sk_select_reuseport() returning errors
- Cases when the bpf prog returns SK_DROP
- Values from sk_reuseport_md
- outer_map => reuseport_array

The test depends on
commit 3eee1f75 ("bpf: fix bpf_skb_load_bytes_relative pkt length check")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/lib/bpf/bpf.c

@@ -92,6 +92,7 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
 	attr.btf_key_type_id = create_attr->btf_key_type_id;
 	attr.btf_value_type_id = create_attr->btf_value_type_id;
 	attr.map_ifindex = create_attr->map_ifindex;
+	attr.inner_map_fd = create_attr->inner_map_fd;
 
 	return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
 }

tools/lib/bpf/bpf.h

@@ -39,6 +39,7 @@ struct bpf_create_map_attr {
 	__u32 btf_key_type_id;
 	__u32 btf_value_type_id;
 	__u32 map_ifindex;
+	__u32 inner_map_fd;
 };
 
 int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr);

tools/testing/selftests/bpf/Makefile

@@ -23,7 +23,7 @@ $(TEST_CUSTOM_PROGS): $(OUTPUT)/%: %.c
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
 	test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
 	test_sock test_btf test_sockmap test_lirc_mode2_user get_cgroup_id_user \
-	test_socket_cookie test_cgroup_storage
+	test_socket_cookie test_cgroup_storage test_select_reuseport
 
 TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \
 	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \
@@ -34,7 +34,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
 	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o \
 	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \
 	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
-	get_cgroup_id_kern.o socket_cookie_prog.o
+	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \

tools/testing/selftests/bpf/bpf_helpers.h

@@ -111,6 +111,8 @@ static int (*bpf_xdp_adjust_tail)(void *ctx, int offset) =
 static int (*bpf_skb_get_xfrm_state)(void *ctx, int index, void *state,
 				     int size, int flags) =
 	(void *) BPF_FUNC_skb_get_xfrm_state;
+static int (*bpf_sk_select_reuseport)(void *ctx, void *map, void *key, __u32 flags) =
+	(void *) BPF_FUNC_sk_select_reuseport;
 static int (*bpf_get_stack)(void *ctx, void *buf, int size, int flags) =
 	(void *) BPF_FUNC_get_stack;
 static int (*bpf_fib_lookup)(void *ctx, struct bpf_fib_lookup *params,
@@ -173,6 +175,8 @@ struct bpf_map_def {
 
 static int (*bpf_skb_load_bytes)(void *ctx, int off, void *to, int len) =
 	(void *) BPF_FUNC_skb_load_bytes;
+static int (*bpf_skb_load_bytes_relative)(void *ctx, int off, void *to, int len, __u32 start_header) =
+	(void *) BPF_FUNC_skb_load_bytes_relative;
 static int (*bpf_skb_store_bytes)(void *ctx, int off, void *from, int len, int flags) =
 	(void *) BPF_FUNC_skb_store_bytes;
 static int (*bpf_l3_csum_replace)(void *ctx, int off, int from, int to, int flags) =

tools/testing/selftests/bpf/test_select_reuseport.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018 Facebook */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <linux/bpf.h>
+#include <linux/err.h>
+#include <linux/types.h>
+#include <linux/if_ether.h>
+#include <sys/types.h>
+#include <sys/epoll.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+#include "bpf_rlimit.h"
+#include "bpf_util.h"
+#include "test_select_reuseport_common.h"
+
+#define MIN_TCPHDR_LEN 20
+#define UDPHDR_LEN 8
+
+#define TCP_SYNCOOKIE_SYSCTL "/proc/sys/net/ipv4/tcp_syncookies"
+#define TCP_FO_SYSCTL "/proc/sys/net/ipv4/tcp_fastopen"
+#define REUSEPORT_ARRAY_SIZE 32
+
+static int result_map, tmp_index_ovr_map, linum_map, data_check_map;
+static enum result expected_results[NR_RESULTS];
+static int sk_fds[REUSEPORT_ARRAY_SIZE];
+static int reuseport_array, outer_map;
+static int select_by_skb_data_prog;
+static int saved_tcp_syncookie;
+static struct bpf_object *obj;
+static int saved_tcp_fo;
+static __u32 index_zero;
+static int epfd;
+
+static union sa46 {
+	struct sockaddr_in6 v6;
+	struct sockaddr_in v4;
+	sa_family_t family;
+} srv_sa;
+
+#define CHECK(condition, tag, format...) ({				\
+	int __ret = !!(condition);					\
+	if (__ret) {							\
+		printf("%s(%d):FAIL:%s ", __func__, __LINE__, tag);	\
+		printf(format);						\
+		exit(-1);						\
+	}								\
+})
+
+static void create_maps(void)
+{
+	struct bpf_create_map_attr attr = {};
+
+	/* Creating reuseport_array */
+	attr.name = "reuseport_array";
+	attr.map_type = BPF_MAP_TYPE_REUSEPORT_SOCKARRAY;
+	attr.key_size = sizeof(__u32);
+	attr.value_size = sizeof(__u32);
+	attr.max_entries = REUSEPORT_ARRAY_SIZE;
+
+	reuseport_array = bpf_create_map_xattr(&attr);
+	CHECK(reuseport_array == -1, "creating reuseport_array",
+	      "reuseport_array:%d errno:%d\n", reuseport_array, errno);
+
+	/* Creating outer_map */
+	attr.name = "outer_map";
+	attr.map_type = BPF_MAP_TYPE_ARRAY_OF_MAPS;
+	attr.key_size = sizeof(__u32);
+	attr.value_size = sizeof(__u32);
+	attr.max_entries = 1;
+	attr.inner_map_fd = reuseport_array;
+	outer_map = bpf_create_map_xattr(&attr);
+	CHECK(outer_map == -1, "creating outer_map",
+	      "outer_map:%d errno:%d\n", outer_map, errno);
+}
+
+static void prepare_bpf_obj(void)
+{
+	struct bpf_program *prog;
+	struct bpf_map *map;
+	int err;
+	struct bpf_object_open_attr attr = {
+		.file = "test_select_reuseport_kern.o",
+		.prog_type = BPF_PROG_TYPE_SK_REUSEPORT,
+	};
+
+	obj = bpf_object__open_xattr(&attr);
+	CHECK(IS_ERR_OR_NULL(obj), "open test_select_reuseport_kern.o",
+	      "obj:%p PTR_ERR(obj):%ld\n", obj, PTR_ERR(obj));
+
+	prog = bpf_program__next(NULL, obj);
+	CHECK(!prog, "get first bpf_program", "!prog\n");
+	bpf_program__set_type(prog, attr.prog_type);
+
+	map = bpf_object__find_map_by_name(obj, "outer_map");
+	CHECK(!map, "find outer_map", "!map\n");
+	err = bpf_map__reuse_fd(map, outer_map);
+	CHECK(err, "reuse outer_map", "err:%d\n", err);
+
+	err = bpf_object__load(obj);
+	CHECK(err, "load bpf_object", "err:%d\n", err);
+
+	select_by_skb_data_prog = bpf_program__fd(prog);
+	CHECK(select_by_skb_data_prog == -1, "get prog fd",
+	      "select_by_skb_data_prog:%d\n", select_by_skb_data_prog);
+
+	map = bpf_object__find_map_by_name(obj, "result_map");
+	CHECK(!map, "find result_map", "!map\n");
+	result_map = bpf_map__fd(map);
+	CHECK(result_map == -1, "get result_map fd",
+	      "result_map:%d\n", result_map);
+
+	map = bpf_object__find_map_by_name(obj, "tmp_index_ovr_map");
+	CHECK(!map, "find tmp_index_ovr_map", "!map\n");
+	tmp_index_ovr_map = bpf_map__fd(map);
+	CHECK(tmp_index_ovr_map == -1, "get tmp_index_ovr_map fd",
+	      "tmp_index_ovr_map:%d\n", tmp_index_ovr_map);
+
+	map = bpf_object__find_map_by_name(obj, "linum_map");
+	CHECK(!map, "find linum_map", "!map\n");
+	linum_map = bpf_map__fd(map);
+	CHECK(linum_map == -1, "get linum_map fd",
+	      "linum_map:%d\n", linum_map);
+
+	map = bpf_object__find_map_by_name(obj, "data_check_map");
+	CHECK(!map, "find data_check_map", "!map\n");
+	data_check_map = bpf_map__fd(map);
+	CHECK(data_check_map == -1, "get data_check_map fd",
+	      "data_check_map:%d\n", data_check_map);
+}
+
+static void sa46_init_loopback(union sa46 *sa, sa_family_t family)
+{
+	memset(sa, 0, sizeof(*sa));
+	sa->family = family;
+	if (sa->family == AF_INET6)
+		sa->v6.sin6_addr = in6addr_loopback;
+	else
+		sa->v4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+}
+
+static void sa46_init_inany(union sa46 *sa, sa_family_t family)
+{
+	memset(sa, 0, sizeof(*sa));
+	sa->family = family;
+	if (sa->family == AF_INET6)
+		sa->v6.sin6_addr = in6addr_any;
+	else
+		sa->v4.sin_addr.s_addr = INADDR_ANY;
+}
+
+static int read_int_sysctl(const char *sysctl)
+{
+	char buf[16];
+	int fd, ret;
+
+	fd = open(sysctl, 0);
+	CHECK(fd == -1, "open(sysctl)", "sysctl:%s fd:%d errno:%d\n",
+	      sysctl, fd, errno);
+
+	ret = read(fd, buf, sizeof(buf));
+	CHECK(ret <= 0, "read(sysctl)", "sysctl:%s ret:%d errno:%d\n",
+	      sysctl, ret, errno);
+	close(fd);
+
+	return atoi(buf);
+}
+
+static void write_int_sysctl(const char *sysctl, int v)
+{
+	int fd, ret, size;
+	char buf[16];
+
+	fd = open(sysctl, O_RDWR);
+	CHECK(fd == -1, "open(sysctl)", "sysctl:%s fd:%d errno:%d\n",
+	      sysctl, fd, errno);
+
+	size = snprintf(buf, sizeof(buf), "%d", v);
+	ret = write(fd, buf, size);
+	CHECK(ret != size, "write(sysctl)",
+	      "sysctl:%s ret:%d size:%d errno:%d\n", sysctl, ret, size, errno);
+	close(fd);
+}
+
+static void restore_sysctls(void)
+{
+	write_int_sysctl(TCP_FO_SYSCTL, saved_tcp_fo);
+	write_int_sysctl(TCP_SYNCOOKIE_SYSCTL, saved_tcp_syncookie);
+}
+
+static void enable_fastopen(void)
+{
+	int fo;
+
+	fo = read_int_sysctl(TCP_FO_SYSCTL);
+	write_int_sysctl(TCP_FO_SYSCTL, fo | 7);
+}
+
+static void enable_syncookie(void)
+{
+	write_int_sysctl(TCP_SYNCOOKIE_SYSCTL, 2);
+}
+
+static void disable_syncookie(void)
+{
+	write_int_sysctl(TCP_SYNCOOKIE_SYSCTL, 0);
+}
+
+static __u32 get_linum(void)
+{
+	__u32 linum;
+	int err;
+
+	err = bpf_map_lookup_elem(linum_map, &index_zero, &linum);
+	CHECK(err == -1, "lookup_elem(linum_map)", "err:%d errno:%d\n",
+	      err, errno);
+
+	return linum;
+}
+
+static void check_data(int type, sa_family_t family, const struct cmd *cmd,
+		       int cli_fd)
+{
+	struct data_check expected = {}, result;
+	union sa46 cli_sa;
+	socklen_t addrlen;
+	int err;
+
+	addrlen = sizeof(cli_sa);
+	err = getsockname(cli_fd, (struct sockaddr *)&cli_sa,
+			  &addrlen);
+	CHECK(err == -1, "getsockname(cli_fd)", "err:%d errno:%d\n",
+	      err, errno);
+
+	err = bpf_map_lookup_elem(data_check_map, &index_zero, &result);
+	CHECK(err == -1, "lookup_elem(data_check_map)", "err:%d errno:%d\n",
+	      err, errno);
+
+	if (type == SOCK_STREAM) {
+		expected.len = MIN_TCPHDR_LEN;
+		expected.ip_protocol = IPPROTO_TCP;
+	} else {
+		expected.len = UDPHDR_LEN;
+		expected.ip_protocol = IPPROTO_UDP;
+	}
+
+	if (family == AF_INET6) {
+		expected.eth_protocol = htons(ETH_P_IPV6);
+		expected.bind_inany = !srv_sa.v6.sin6_addr.s6_addr32[3] &&
+			!srv_sa.v6.sin6_addr.s6_addr32[2] &&
+			!srv_sa.v6.sin6_addr.s6_addr32[1] &&
+			!srv_sa.v6.sin6_addr.s6_addr32[0];
+
+		memcpy(&expected.skb_addrs[0], cli_sa.v6.sin6_addr.s6_addr32,
+		       sizeof(cli_sa.v6.sin6_addr));
+		memcpy(&expected.skb_addrs[4], &in6addr_loopback,
+		       sizeof(in6addr_loopback));
+		expected.skb_ports[0] = cli_sa.v6.sin6_port;
+		expected.skb_ports[1] = srv_sa.v6.sin6_port;
+	} else {
+		expected.eth_protocol = htons(ETH_P_IP);
+		expected.bind_inany = !srv_sa.v4.sin_addr.s_addr;
+
+		expected.skb_addrs[0] = cli_sa.v4.sin_addr.s_addr;
+		expected.skb_addrs[1] = htonl(INADDR_LOOPBACK);
+		expected.skb_ports[0] = cli_sa.v4.sin_port;
+		expected.skb_ports[1] = srv_sa.v4.sin_port;
+	}
+
+	if (memcmp(&result, &expected, offsetof(struct data_check,
+						equal_check_end))) {
+		printf("unexpected data_check\n");
+		printf("  result: (0x%x, %u, %u)\n",
+		       result.eth_protocol, result.ip_protocol,
+		       result.bind_inany);
+		printf("expected: (0x%x, %u, %u)\n",
+		       expected.eth_protocol, expected.ip_protocol,
+		       expected.bind_inany);
+		CHECK(1, "data_check result != expected",
+		      "bpf_prog_linum:%u\n", get_linum());
+	}
+
+	CHECK(!result.hash, "data_check result.hash empty",
+	      "result.hash:%u", result.hash);
+
+	expected.len += cmd ? sizeof(*cmd) : 0;
+	if (type == SOCK_STREAM)
+		CHECK(expected.len > result.len, "expected.len > result.len",
+		      "expected.len:%u result.len:%u bpf_prog_linum:%u\n",
+		      expected.len, result.len, get_linum());
+	else
+		CHECK(expected.len != result.len, "expected.len != result.len",
+		      "expected.len:%u result.len:%u bpf_prog_linum:%u\n",
+		      expected.len, result.len, get_linum());
+}
+
+static void check_results(void)
+{
+	__u32 results[NR_RESULTS];
+	__u32 i, broken = 0;
+	int err;
+
+	for (i = 0; i < NR_RESULTS; i++) {
+		err = bpf_map_lookup_elem(result_map, &i, &results[i]);
+		CHECK(err == -1, "lookup_elem(result_map)",
+		      "i:%u err:%d errno:%d\n", i, err, errno);
+	}
+
+	for (i = 0; i < NR_RESULTS; i++) {
+		if (results[i] != expected_results[i]) {
+			broken = i;
+			break;
+		}
+	}
+
+	if (i == NR_RESULTS)
+		return;
+
+	printf("unexpected result\n");
+	printf(" result: [");
+	printf("%u", results[0]);
+	for (i = 1; i < NR_RESULTS; i++)
+		printf(", %u", results[i]);
+	printf("]\n");
+
+	printf("expected: [");
+	printf("%u", expected_results[0]);
+	for (i = 1; i < NR_RESULTS; i++)
+		printf(", %u", expected_results[i]);
+	printf("]\n");
+
+	CHECK(expected_results[broken] != results[broken],
+	      "unexpected result",
+	      "expected_results[%u] != results[%u] bpf_prog_linum:%u\n",
+	      broken, broken, get_linum());
+}
+
+static int send_data(int type, sa_family_t family, void *data, size_t len,
+		     enum result expected)
+{
+	union sa46 cli_sa;
+	int fd, err;
+
+	fd = socket(family, type, 0);
+	CHECK(fd == -1, "socket()", "fd:%d errno:%d\n", fd, errno);
+
+	sa46_init_loopback(&cli_sa, family);
+	err = bind(fd, (struct sockaddr *)&cli_sa, sizeof(cli_sa));
+	CHECK(fd == -1, "bind(cli_sa)", "err:%d errno:%d\n", err, errno);
+
+	err = sendto(fd, data, len, MSG_FASTOPEN, (struct sockaddr *)&srv_sa,
+		     sizeof(srv_sa));
+	CHECK(err != len && expected >= PASS,
+	      "sendto()", "family:%u err:%d errno:%d expected:%d\n",
+	      family, err, errno, expected);
+
+	return fd;
+}
+
+static void do_test(int type, sa_family_t family, struct cmd *cmd,
+		    enum result expected)
+{
+	int nev, srv_fd, cli_fd;
+	struct epoll_event ev;
+	struct cmd rcv_cmd;
+	ssize_t nread;
+
+	cli_fd = send_data(type, family, cmd, cmd ? sizeof(*cmd) : 0,
+			   expected);
+	nev = epoll_wait(epfd, &ev, 1, expected >= PASS ? 5 : 0);
+	CHECK((nev <= 0 && expected >= PASS) ||
+	      (nev > 0 && expected < PASS),
+	      "nev <> expected",
+	      "nev:%d expected:%d type:%d family:%d data:(%d, %d)\n",
+	      nev, expected, type, family,
+	      cmd ? cmd->reuseport_index : -1,
+	      cmd ? cmd->pass_on_failure : -1);
+	check_results();
+	check_data(type, family, cmd, cli_fd);
+
+	if (expected < PASS)
+		return;
+
+	CHECK(expected != PASS_ERR_SK_SELECT_REUSEPORT &&
+	      cmd->reuseport_index != ev.data.u32,
+	      "check cmd->reuseport_index",
+	      "cmd:(%u, %u) ev.data.u32:%u\n",
+	      cmd->pass_on_failure, cmd->reuseport_index, ev.data.u32);
+
+	srv_fd = sk_fds[ev.data.u32];
+	if (type == SOCK_STREAM) {
+		int new_fd = accept(srv_fd, NULL, 0);
+
+		CHECK(new_fd == -1, "accept(srv_fd)",
+		      "ev.data.u32:%u new_fd:%d errno:%d\n",
+		      ev.data.u32, new_fd, errno);
+
+		nread = recv(new_fd, &rcv_cmd, sizeof(rcv_cmd), MSG_DONTWAIT);
+		CHECK(nread != sizeof(rcv_cmd),
+		      "recv(new_fd)",
+		      "ev.data.u32:%u nread:%zd sizeof(rcv_cmd):%zu errno:%d\n",
+		      ev.data.u32, nread, sizeof(rcv_cmd), errno);
+
+		close(new_fd);
+	} else {
+		nread = recv(srv_fd, &rcv_cmd, sizeof(rcv_cmd), MSG_DONTWAIT);
+		CHECK(nread != sizeof(rcv_cmd),
+		      "recv(sk_fds)",
+		      "ev.data.u32:%u nread:%zd sizeof(rcv_cmd):%zu errno:%d\n",
+		      ev.data.u32, nread, sizeof(rcv_cmd), errno);
+	}
+
+	close(cli_fd);
+}
+
+static void test_err_inner_map(int type, sa_family_t family)
+{
+	struct cmd cmd = {
+		.reuseport_index = 0,
+		.pass_on_failure = 0,
+	};
+
+	printf("%s: ", __func__);
+	expected_results[DROP_ERR_INNER_MAP]++;
+	do_test(type, family, &cmd, DROP_ERR_INNER_MAP);
+	printf("OK\n");
+}
+
+static void test_err_skb_data(int type, sa_family_t family)
+{
+	printf("%s: ", __func__);
+	expected_results[DROP_ERR_SKB_DATA]++;
+	do_test(type, family, NULL, DROP_ERR_SKB_DATA);
+	printf("OK\n");
+}
+
+static void test_err_sk_select_port(int type, sa_family_t family)
+{
+	struct cmd cmd = {
+		.reuseport_index = REUSEPORT_ARRAY_SIZE,
+		.pass_on_failure = 0,
+	};
+
+	printf("%s: ", __func__);
+	expected_results[DROP_ERR_SK_SELECT_REUSEPORT]++;
+	do_test(type, family, &cmd, DROP_ERR_SK_SELECT_REUSEPORT);
+	printf("OK\n");
+}
+
+static void test_pass(int type, sa_family_t family)
+{
+	struct cmd cmd;
+	int i;
+
+	printf("%s: ", __func__);
+	cmd.pass_on_failure = 0;
+	for (i = 0; i < REUSEPORT_ARRAY_SIZE; i++) {
+		expected_results[PASS]++;
+		cmd.reuseport_index = i;
+		do_test(type, family, &cmd, PASS);
+	}
+	printf("OK\n");
+}
+
+static void test_syncookie(int type, sa_family_t family)
+{
+	int err, tmp_index = 1;
+	struct cmd cmd = {
+		.reuseport_index = 0,
+		.pass_on_failure = 0,
+	};
+
+	if (type != SOCK_STREAM)
+		return;
+
+	printf("%s: ", __func__);
+	/*
+	 * +1 for TCP-SYN and
+	 * +1 for the TCP-ACK (ack the syncookie)
+	 */
+	expected_results[PASS] += 2;
+	enable_syncookie();
+	/*
+	 * Simulate TCP-SYN and TCP-ACK are handled by two different sk:
+	 * TCP-SYN: select sk_fds[tmp_index = 1] tmp_index is from the
+	 *          tmp_index_ovr_map
+	 * TCP-ACK: select sk_fds[reuseport_index = 0] reuseport_index
+	 *          is from the cmd.reuseport_index
+	 */
+	err = bpf_map_update_elem(tmp_index_ovr_map, &index_zero,
+				  &tmp_index, BPF_ANY);
+	CHECK(err == -1, "update_elem(tmp_index_ovr_map, 0, 1)",
+	      "err:%d errno:%d\n", err, errno);
+	do_test(type, family, &cmd, PASS);
+	err = bpf_map_lookup_elem(tmp_index_ovr_map, &index_zero,
+				  &tmp_index);
+	CHECK(err == -1 || tmp_index != -1,
+	      "lookup_elem(tmp_index_ovr_map)",
+	      "err:%d errno:%d tmp_index:%d\n",
+	      err, errno, tmp_index);
+	disable_syncookie();
+	printf("OK\n");
+}
+
+static void test_pass_on_err(int type, sa_family_t family)
+{
+	struct cmd cmd = {
+		.reuseport_index = REUSEPORT_ARRAY_SIZE,
+		.pass_on_failure = 1,
+	};
+
+	printf("%s: ", __func__);
+	expected_results[PASS_ERR_SK_SELECT_REUSEPORT] += 1;
+	do_test(type, family, &cmd, PASS_ERR_SK_SELECT_REUSEPORT);
+	printf("OK\n");
+}
+
+static void prepare_sk_fds(int type, sa_family_t family, bool inany)
+{
+	const int first = REUSEPORT_ARRAY_SIZE - 1;
+	int i, err, optval = 1;
+	struct epoll_event ev;
+	socklen_t addrlen;
+
+	if (inany)
+		sa46_init_inany(&srv_sa, family);
+	else
+		sa46_init_loopback(&srv_sa, family);
+	addrlen = sizeof(srv_sa);
+
+	/*
+	 * The sk_fds[] is filled from the back such that the order
+	 * is exactly opposite to the (struct sock_reuseport *)reuse->socks[].
+	 */
+	for (i = first; i >= 0; i--) {
+		sk_fds[i] = socket(family, type, 0);
+		CHECK(sk_fds[i] == -1, "socket()", "sk_fds[%d]:%d errno:%d\n",
+		      i, sk_fds[i], errno);
+		err = setsockopt(sk_fds[i], SOL_SOCKET, SO_REUSEPORT,
+				 &optval, sizeof(optval));
+		CHECK(err == -1, "setsockopt(SO_REUSEPORT)",
+		      "sk_fds[%d] err:%d errno:%d\n",
+		      i, err, errno);
+
+		if (i == first) {
+			err = setsockopt(sk_fds[i], SOL_SOCKET,
+					 SO_ATTACH_REUSEPORT_EBPF,
+					 &select_by_skb_data_prog,
+					 sizeof(select_by_skb_data_prog));
+			CHECK(err == -1, "setsockopt(SO_ATTACH_REUEPORT_EBPF)",
+			      "err:%d errno:%d\n", err, errno);
+		}
+
+		err = bind(sk_fds[i], (struct sockaddr *)&srv_sa, addrlen);
+		CHECK(err == -1, "bind()", "sk_fds[%d] err:%d errno:%d\n",
+		      i, err, errno);
+
+		if (type == SOCK_STREAM) {
+			err = listen(sk_fds[i], 10);
+			CHECK(err == -1, "listen()",
+			      "sk_fds[%d] err:%d errno:%d\n",
+			      i, err, errno);
+		}
+
+		err = bpf_map_update_elem(reuseport_array, &i, &sk_fds[i],
+					  BPF_NOEXIST);
+		CHECK(err == -1, "update_elem(reuseport_array)",
+		      "sk_fds[%d] err:%d errno:%d\n", i, err, errno);
+
+		if (i == first) {
+			socklen_t addrlen = sizeof(srv_sa);
+
+			err = getsockname(sk_fds[i], (struct sockaddr *)&srv_sa,
+					  &addrlen);
+			CHECK(err == -1, "getsockname()",
+			      "sk_fds[%d] err:%d errno:%d\n", i, err, errno);
+		}
+	}
+
+	epfd = epoll_create(1);
+	CHECK(epfd == -1, "epoll_create(1)",
+	      "epfd:%d errno:%d\n", epfd, errno);
+
+	ev.events = EPOLLIN;
+	for (i = 0; i < REUSEPORT_ARRAY_SIZE; i++) {
+		ev.data.u32 = i;
+		err = epoll_ctl(epfd, EPOLL_CTL_ADD, sk_fds[i], &ev);
+		CHECK(err, "epoll_ctl(EPOLL_CTL_ADD)", "sk_fds[%d]\n", i);
+	}
+}
+
+static void setup_per_test(int type, unsigned short family, bool inany)
+{
+	int ovr = -1, err;
+
+	prepare_sk_fds(type, family, inany);
+	err = bpf_map_update_elem(tmp_index_ovr_map, &index_zero, &ovr,
+				  BPF_ANY);
+	CHECK(err == -1, "update_elem(tmp_index_ovr_map, 0, -1)",
+	      "err:%d errno:%d\n", err, errno);
+}
+
+static void cleanup_per_test(void)
+{
+	int i, err;
+
+	for (i = 0; i < REUSEPORT_ARRAY_SIZE; i++)
+		close(sk_fds[i]);
+	close(epfd);
+
+	err = bpf_map_delete_elem(outer_map, &index_zero);
+	CHECK(err == -1, "delete_elem(outer_map)",
+	      "err:%d errno:%d\n", err, errno);
+}
+
+static void cleanup(void)
+{
+	close(outer_map);
+	close(reuseport_array);
+	bpf_object__close(obj);
+}
+
+static void test_all(void)
+{
+	/* Extra SOCK_STREAM to test bind_inany==true */
+	const int types[] = { SOCK_STREAM, SOCK_DGRAM, SOCK_STREAM };
+	const char * const type_strings[] = { "TCP", "UDP", "TCP" };
+	const char * const family_strings[] = { "IPv6", "IPv4" };
+	const unsigned short families[] = { AF_INET6, AF_INET };
+	const bool bind_inany[] = { false, false, true };
+	int t, f, err;
+
+	for (f = 0; f < ARRAY_SIZE(families); f++) {
+		unsigned short family = families[f];
+
+		for (t = 0; t < ARRAY_SIZE(types); t++) {
+			bool inany = bind_inany[t];
+			int type = types[t];
+
+			printf("######## %s/%s %s ########\n",
+			       family_strings[f], type_strings[t],
+				inany ? " INANY  " : "LOOPBACK");
+
+			setup_per_test(type, family, inany);
+
+			test_err_inner_map(type, family);
+
+			/* Install reuseport_array to the outer_map */
+			err = bpf_map_update_elem(outer_map, &index_zero,
+						  &reuseport_array, BPF_ANY);
+			CHECK(err == -1, "update_elem(outer_map)",
+			      "err:%d errno:%d\n", err, errno);
+
+			test_err_skb_data(type, family);
+			test_err_sk_select_port(type, family);
+			test_pass(type, family);
+			test_syncookie(type, family);
+			test_pass_on_err(type, family);
+
+			cleanup_per_test();
+			printf("\n");
+		}
+	}
+}
+
+int main(int argc, const char **argv)
+{
+	create_maps();
+	prepare_bpf_obj();
+	saved_tcp_fo = read_int_sysctl(TCP_FO_SYSCTL);
+	saved_tcp_syncookie = read_int_sysctl(TCP_SYNCOOKIE_SYSCTL);
+	enable_fastopen();
+	disable_syncookie();
+	atexit(restore_sysctls);
+
+	test_all();
+
+	cleanup();
+	return 0;
+}

tools/testing/selftests/bpf/test_select_reuseport_common.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#ifndef __TEST_SELECT_REUSEPORT_COMMON_H
+#define __TEST_SELECT_REUSEPORT_COMMON_H
+
+#include <linux/types.h>
+
+enum result {
+	DROP_ERR_INNER_MAP,
+	DROP_ERR_SKB_DATA,
+	DROP_ERR_SK_SELECT_REUSEPORT,
+	DROP_MISC,
+	PASS,
+	PASS_ERR_SK_SELECT_REUSEPORT,
+	NR_RESULTS,
+};
+
+struct cmd {
+	__u32 reuseport_index;
+	__u32 pass_on_failure;
+};
+
+struct data_check {
+	__u32 ip_protocol;
+	__u32 skb_addrs[8];
+	__u16 skb_ports[2];
+	__u16 eth_protocol;
+	__u8  bind_inany;
+	__u8  equal_check_end[0];
+
+	__u32 len;
+	__u32 hash;
+};
+
+#endif

tools/testing/selftests/bpf/test_select_reuseport_kern.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018 Facebook */
+
+#include <stdlib.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/bpf.h>
+#include <linux/types.h>
+#include <linux/if_ether.h>
+
+#include "bpf_endian.h"
+#include "bpf_helpers.h"
+#include "test_select_reuseport_common.h"
+
+int _version SEC("version") = 1;
+
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#endif
+
+struct bpf_map_def SEC("maps") outer_map = {
+	.type = BPF_MAP_TYPE_ARRAY_OF_MAPS,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+};
+
+struct bpf_map_def SEC("maps") result_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = NR_RESULTS,
+};
+
+struct bpf_map_def SEC("maps") tmp_index_ovr_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(int),
+	.max_entries = 1,
+};
+
+struct bpf_map_def SEC("maps") linum_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+};
+
+struct bpf_map_def SEC("maps") data_check_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(struct data_check),
+	.max_entries = 1,
+};
+
+#define GOTO_DONE(_result) ({			\
+	result = (_result);			\
+	linum = __LINE__;			\
+	goto done;				\
+})
+
+SEC("select_by_skb_data")
+int _select_by_skb_data(struct sk_reuseport_md *reuse_md)
+{
+	__u32 linum, index = 0, flags = 0, index_zero = 0;
+	__u32 *result_cnt, *linum_value;
+	struct data_check data_check = {};
+	struct cmd *cmd, cmd_copy;
+	void *data, *data_end;
+	void *reuseport_array;
+	enum result result;
+	int *index_ovr;
+	int err;
+
+	data = reuse_md->data;
+	data_end = reuse_md->data_end;
+	data_check.len = reuse_md->len;
+	data_check.eth_protocol = reuse_md->eth_protocol;
+	data_check.ip_protocol = reuse_md->ip_protocol;
+	data_check.hash = reuse_md->hash;
+	data_check.bind_inany = reuse_md->bind_inany;
+	if (data_check.eth_protocol == bpf_htons(ETH_P_IP)) {
+		if (bpf_skb_load_bytes_relative(reuse_md,
+						offsetof(struct iphdr, saddr),
+						data_check.skb_addrs, 8,
+						BPF_HDR_START_NET))
+			GOTO_DONE(DROP_MISC);
+	} else {
+		if (bpf_skb_load_bytes_relative(reuse_md,
+						offsetof(struct ipv6hdr, saddr),
+						data_check.skb_addrs, 32,
+						BPF_HDR_START_NET))
+			GOTO_DONE(DROP_MISC);
+	}
+
+	/*
+	 * The ip_protocol could be a compile time decision
+	 * if the bpf_prog.o is dedicated to either TCP or
+	 * UDP.
+	 *
+	 * Otherwise, reuse_md->ip_protocol or
+	 * the protocol field in the iphdr can be used.
+	 */
+	if (data_check.ip_protocol == IPPROTO_TCP) {
+		struct tcphdr *th = data;
+
+		if (th + 1 > data_end)
+			GOTO_DONE(DROP_MISC);
+
+		data_check.skb_ports[0] = th->source;
+		data_check.skb_ports[1] = th->dest;
+
+		if ((th->doff << 2) + sizeof(*cmd) > data_check.len)
+			GOTO_DONE(DROP_ERR_SKB_DATA);
+		if (bpf_skb_load_bytes(reuse_md, th->doff << 2, &cmd_copy,
+				       sizeof(cmd_copy)))
+			GOTO_DONE(DROP_MISC);
+		cmd = &cmd_copy;
+	} else if (data_check.ip_protocol == IPPROTO_UDP) {
+		struct udphdr *uh = data;
+
+		if (uh + 1 > data_end)
+			GOTO_DONE(DROP_MISC);
+
+		data_check.skb_ports[0] = uh->source;
+		data_check.skb_ports[1] = uh->dest;
+
+		if (sizeof(struct udphdr) + sizeof(*cmd) > data_check.len)
+			GOTO_DONE(DROP_ERR_SKB_DATA);
+		if (data + sizeof(struct udphdr) + sizeof(*cmd) > data_end) {
+			if (bpf_skb_load_bytes(reuse_md, sizeof(struct udphdr),
+					       &cmd_copy, sizeof(cmd_copy)))
+				GOTO_DONE(DROP_MISC);
+			cmd = &cmd_copy;
+		} else {
+			cmd = data + sizeof(struct udphdr);
+		}
+	} else {
+		GOTO_DONE(DROP_MISC);
+	}
+
+	reuseport_array = bpf_map_lookup_elem(&outer_map, &index_zero);
+	if (!reuseport_array)
+		GOTO_DONE(DROP_ERR_INNER_MAP);
+
+	index = cmd->reuseport_index;
+	index_ovr = bpf_map_lookup_elem(&tmp_index_ovr_map, &index_zero);
+	if (!index_ovr)
+		GOTO_DONE(DROP_MISC);
+
+	if (*index_ovr != -1) {
+		index = *index_ovr;
+		*index_ovr = -1;
+	}
+	err = bpf_sk_select_reuseport(reuse_md, reuseport_array, &index,
+				      flags);
+	if (!err)
+		GOTO_DONE(PASS);
+
+	if (cmd->pass_on_failure)
+		GOTO_DONE(PASS_ERR_SK_SELECT_REUSEPORT);
+	else
+		GOTO_DONE(DROP_ERR_SK_SELECT_REUSEPORT);
+
+done:
+	result_cnt = bpf_map_lookup_elem(&result_map, &result);
+	if (!result_cnt)
+		return SK_DROP;
+
+	bpf_map_update_elem(&linum_map, &index_zero, &linum, BPF_ANY);
+	bpf_map_update_elem(&data_check_map, &index_zero, &data_check, BPF_ANY);
+
+	(*result_cnt)++;
+	return result < PASS ? SK_DROP : SK_PASS;
+}
+
+char _license[] SEC("license") = "GPL";