bpf: Add test_sock_fields for skb->sk and bpf_tcp_sock

This patch adds a C program to show the usage on
skb->sk and bpf_tcp_sock.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -23,7 +23,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	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_select_reuseport test_section_names \
-	test_netcnt test_tcpnotify_user
+	test_netcnt test_tcpnotify_user test_sock_fields
 
 BPF_OBJ_FILES = \
 	test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \
@@ -35,7 +35,8 @@ BPF_OBJ_FILES = \
 	sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
 	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
 	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o test_xdp_vlan.o \
-	xdp_dummy.o test_map_in_map.o test_spin_lock.o test_map_lock.o
+	xdp_dummy.o test_map_in_map.o test_spin_lock.o test_map_lock.o \
+	test_sock_fields_kern.o
 
 # Objects are built with default compilation flags and with sub-register
 # code-gen enabled.
@@ -111,6 +112,7 @@ $(OUTPUT)/test_progs: trace_helpers.c
 $(OUTPUT)/get_cgroup_id_user: cgroup_helpers.c
 $(OUTPUT)/test_cgroup_storage: cgroup_helpers.c
 $(OUTPUT)/test_netcnt: cgroup_helpers.c
+$(OUTPUT)/test_sock_fields: cgroup_helpers.c
 
 .PHONY: force
 

tools/testing/selftests/bpf/bpf_helpers.h

@@ -176,6 +176,10 @@ static void (*bpf_spin_lock)(struct bpf_spin_lock *lock) =
 	(void *) BPF_FUNC_spin_lock;
 static void (*bpf_spin_unlock)(struct bpf_spin_lock *lock) =
 	(void *) BPF_FUNC_spin_unlock;
+static struct bpf_sock *(*bpf_sk_fullsock)(struct bpf_sock *sk) =
+	(void *) BPF_FUNC_sk_fullsock;
+static struct bpf_tcp_sock *(*bpf_tcp_sock)(struct bpf_sock *sk) =
+	(void *) BPF_FUNC_tcp_sock;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions

tools/testing/selftests/bpf/test_sock_fields.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook */
+
+#include <sys/socket.h>
+#include <sys/epoll.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "cgroup_helpers.h"
+
+enum bpf_array_idx {
+	SRV_IDX,
+	CLI_IDX,
+	__NR_BPF_ARRAY_IDX,
+};
+
+#define CHECK(condition, tag, format...) ({				\
+	int __ret = !!(condition);					\
+	if (__ret) {							\
+		printf("%s(%d):FAIL:%s ", __func__, __LINE__, tag);	\
+		printf(format);						\
+		printf("\n");						\
+		exit(-1);						\
+	}								\
+})
+
+#define TEST_CGROUP "/test-bpf-sock-fields"
+#define DATA "Hello BPF!"
+#define DATA_LEN sizeof(DATA)
+
+static struct sockaddr_in6 srv_sa6, cli_sa6;
+static int linum_map_fd;
+static int addr_map_fd;
+static int tp_map_fd;
+static int sk_map_fd;
+static __u32 srv_idx = SRV_IDX;
+static __u32 cli_idx = CLI_IDX;
+
+static void init_loopback6(struct sockaddr_in6 *sa6)
+{
+	memset(sa6, 0, sizeof(*sa6));
+	sa6->sin6_family = AF_INET6;
+	sa6->sin6_addr = in6addr_loopback;
+}
+
+static void print_sk(const struct bpf_sock *sk)
+{
+	char src_ip4[24], dst_ip4[24];
+	char src_ip6[64], dst_ip6[64];
+
+	inet_ntop(AF_INET, &sk->src_ip4, src_ip4, sizeof(src_ip4));
+	inet_ntop(AF_INET6, &sk->src_ip6, src_ip6, sizeof(src_ip6));
+	inet_ntop(AF_INET, &sk->dst_ip4, dst_ip4, sizeof(dst_ip4));
+	inet_ntop(AF_INET6, &sk->dst_ip6, dst_ip6, sizeof(dst_ip6));
+
+	printf("state:%u bound_dev_if:%u family:%u type:%u protocol:%u mark:%u priority:%u "
+	       "src_ip4:%x(%s) src_ip6:%x:%x:%x:%x(%s) src_port:%u "
+	       "dst_ip4:%x(%s) dst_ip6:%x:%x:%x:%x(%s) dst_port:%u\n",
+	       sk->state, sk->bound_dev_if, sk->family, sk->type, sk->protocol,
+	       sk->mark, sk->priority,
+	       sk->src_ip4, src_ip4,
+	       sk->src_ip6[0], sk->src_ip6[1], sk->src_ip6[2], sk->src_ip6[3],
+	       src_ip6, sk->src_port,
+	       sk->dst_ip4, dst_ip4,
+	       sk->dst_ip6[0], sk->dst_ip6[1], sk->dst_ip6[2], sk->dst_ip6[3],
+	       dst_ip6, ntohs(sk->dst_port));
+}
+
+static void print_tp(const struct bpf_tcp_sock *tp)
+{
+	printf("snd_cwnd:%u srtt_us:%u rtt_min:%u snd_ssthresh:%u rcv_nxt:%u "
+	       "snd_nxt:%u snd:una:%u mss_cache:%u ecn_flags:%u "
+	       "rate_delivered:%u rate_interval_us:%u packets_out:%u "
+	       "retrans_out:%u total_retrans:%u segs_in:%u data_segs_in:%u "
+	       "segs_out:%u data_segs_out:%u lost_out:%u sacked_out:%u "
+	       "bytes_received:%llu bytes_acked:%llu\n",
+	       tp->snd_cwnd, tp->srtt_us, tp->rtt_min, tp->snd_ssthresh,
+	       tp->rcv_nxt, tp->snd_nxt, tp->snd_una, tp->mss_cache,
+	       tp->ecn_flags, tp->rate_delivered, tp->rate_interval_us,
+	       tp->packets_out, tp->retrans_out, tp->total_retrans,
+	       tp->segs_in, tp->data_segs_in, tp->segs_out,
+	       tp->data_segs_out, tp->lost_out, tp->sacked_out,
+	       tp->bytes_received, tp->bytes_acked);
+}
+
+static void check_result(void)
+{
+	struct bpf_tcp_sock srv_tp, cli_tp;
+	struct bpf_sock srv_sk, cli_sk;
+	__u32 linum, idx0 = 0;
+	int err;
+
+	err = bpf_map_lookup_elem(linum_map_fd, &idx0, &linum);
+	CHECK(err == -1, "bpf_map_lookup_elem(linum_map_fd)",
+	      "err:%d errno:%d", err, errno);
+
+	err = bpf_map_lookup_elem(sk_map_fd, &srv_idx, &srv_sk);
+	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &srv_idx)",
+	      "err:%d errno:%d", err, errno);
+	err = bpf_map_lookup_elem(tp_map_fd, &srv_idx, &srv_tp);
+	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &srv_idx)",
+	      "err:%d errno:%d", err, errno);
+
+	err = bpf_map_lookup_elem(sk_map_fd, &cli_idx, &cli_sk);
+	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &cli_idx)",
+	      "err:%d errno:%d", err, errno);
+	err = bpf_map_lookup_elem(tp_map_fd, &cli_idx, &cli_tp);
+	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &cli_idx)",
+	      "err:%d errno:%d", err, errno);
+
+	printf("srv_sk: ");
+	print_sk(&srv_sk);
+	printf("\n");
+
+	printf("cli_sk: ");
+	print_sk(&cli_sk);
+	printf("\n");
+
+	printf("srv_tp: ");
+	print_tp(&srv_tp);
+	printf("\n");
+
+	printf("cli_tp: ");
+	print_tp(&cli_tp);
+	printf("\n");
+
+	CHECK(srv_sk.state == 10 ||
+	      !srv_sk.state ||
+	      srv_sk.family != AF_INET6 ||
+	      srv_sk.protocol != IPPROTO_TCP ||
+	      memcmp(srv_sk.src_ip6, &in6addr_loopback,
+		     sizeof(srv_sk.src_ip6)) ||
+	      memcmp(srv_sk.dst_ip6, &in6addr_loopback,
+		     sizeof(srv_sk.dst_ip6)) ||
+	      srv_sk.src_port != ntohs(srv_sa6.sin6_port) ||
+	      srv_sk.dst_port != cli_sa6.sin6_port,
+	      "Unexpected srv_sk", "Check srv_sk output. linum:%u", linum);
+
+	CHECK(cli_sk.state == 10 ||
+	      !cli_sk.state ||
+	      cli_sk.family != AF_INET6 ||
+	      cli_sk.protocol != IPPROTO_TCP ||
+	      memcmp(cli_sk.src_ip6, &in6addr_loopback,
+		     sizeof(cli_sk.src_ip6)) ||
+	      memcmp(cli_sk.dst_ip6, &in6addr_loopback,
+		     sizeof(cli_sk.dst_ip6)) ||
+	      cli_sk.src_port != ntohs(cli_sa6.sin6_port) ||
+	      cli_sk.dst_port != srv_sa6.sin6_port,
+	      "Unexpected cli_sk", "Check cli_sk output. linum:%u", linum);
+
+	CHECK(srv_tp.data_segs_out != 1 ||
+	      srv_tp.data_segs_in ||
+	      srv_tp.snd_cwnd != 10 ||
+	      srv_tp.total_retrans ||
+	      srv_tp.bytes_acked != DATA_LEN,
+	      "Unexpected srv_tp", "Check srv_tp output. linum:%u", linum);
+
+	CHECK(cli_tp.data_segs_out ||
+	      cli_tp.data_segs_in != 1 ||
+	      cli_tp.snd_cwnd != 10 ||
+	      cli_tp.total_retrans ||
+	      cli_tp.bytes_received != DATA_LEN,
+	      "Unexpected cli_tp", "Check cli_tp output. linum:%u", linum);
+}
+
+static void test(void)
+{
+	int listen_fd, cli_fd, accept_fd, epfd, err;
+	struct epoll_event ev;
+	socklen_t addrlen;
+
+	addrlen = sizeof(struct sockaddr_in6);
+	ev.events = EPOLLIN;
+
+	epfd = epoll_create(1);
+	CHECK(epfd == -1, "epoll_create()", "epfd:%d errno:%d", epfd, errno);
+
+	/* Prepare listen_fd */
+	listen_fd = socket(AF_INET6, SOCK_STREAM | SOCK_NONBLOCK, 0);
+	CHECK(listen_fd == -1, "socket()", "listen_fd:%d errno:%d",
+	      listen_fd, errno);
+
+	init_loopback6(&srv_sa6);
+	err = bind(listen_fd, (struct sockaddr *)&srv_sa6, sizeof(srv_sa6));
+	CHECK(err, "bind(listen_fd)", "err:%d errno:%d", err, errno);
+
+	err = getsockname(listen_fd, (struct sockaddr *)&srv_sa6, &addrlen);
+	CHECK(err, "getsockname(listen_fd)", "err:%d errno:%d", err, errno);
+
+	err = listen(listen_fd, 1);
+	CHECK(err, "listen(listen_fd)", "err:%d errno:%d", err, errno);
+
+	/* Prepare cli_fd */
+	cli_fd = socket(AF_INET6, SOCK_STREAM | SOCK_NONBLOCK, 0);
+	CHECK(cli_fd == -1, "socket()", "cli_fd:%d errno:%d", cli_fd, errno);
+
+	init_loopback6(&cli_sa6);
+	err = bind(cli_fd, (struct sockaddr *)&cli_sa6, sizeof(cli_sa6));
+	CHECK(err, "bind(cli_fd)", "err:%d errno:%d", err, errno);
+
+	err = getsockname(cli_fd, (struct sockaddr *)&cli_sa6, &addrlen);
+	CHECK(err, "getsockname(cli_fd)", "err:%d errno:%d",
+	      err, errno);
+
+	/* Update addr_map with srv_sa6 and cli_sa6 */
+	err = bpf_map_update_elem(addr_map_fd, &srv_idx, &srv_sa6, 0);
+	CHECK(err, "map_update", "err:%d errno:%d", err, errno);
+
+	err = bpf_map_update_elem(addr_map_fd, &cli_idx, &cli_sa6, 0);
+	CHECK(err, "map_update", "err:%d errno:%d", err, errno);
+
+	/* Connect from cli_sa6 to srv_sa6 */
+	err = connect(cli_fd, (struct sockaddr *)&srv_sa6, addrlen);
+	printf("srv_sa6.sin6_port:%u cli_sa6.sin6_port:%u\n\n",
+	       ntohs(srv_sa6.sin6_port), ntohs(cli_sa6.sin6_port));
+	CHECK(err && errno != EINPROGRESS,
+	      "connect(cli_fd)", "err:%d errno:%d", err, errno);
+
+	ev.data.fd = listen_fd;
+	err = epoll_ctl(epfd, EPOLL_CTL_ADD, listen_fd, &ev);
+	CHECK(err, "epoll_ctl(EPOLL_CTL_ADD, listen_fd)", "err:%d errno:%d",
+	      err, errno);
+
+	/* Accept the connection */
+	/* Have some timeout in accept(listen_fd). Just in case. */
+	err = epoll_wait(epfd, &ev, 1, 1000);
+	CHECK(err != 1 || ev.data.fd != listen_fd,
+	      "epoll_wait(listen_fd)",
+	      "err:%d errno:%d ev.data.fd:%d listen_fd:%d",
+	      err, errno, ev.data.fd, listen_fd);
+
+	accept_fd = accept(listen_fd, NULL, NULL);
+	CHECK(accept_fd == -1, "accept(listen_fd)", "accept_fd:%d errno:%d",
+	      accept_fd, errno);
+	close(listen_fd);
+
+	/* Send some data from accept_fd to cli_fd */
+	err = send(accept_fd, DATA, DATA_LEN, 0);
+	CHECK(err != DATA_LEN, "send(accept_fd)", "err:%d errno:%d",
+	      err, errno);
+
+	/* Have some timeout in recv(cli_fd). Just in case. */
+	ev.data.fd = cli_fd;
+	err = epoll_ctl(epfd, EPOLL_CTL_ADD, cli_fd, &ev);
+	CHECK(err, "epoll_ctl(EPOLL_CTL_ADD, cli_fd)", "err:%d errno:%d",
+	      err, errno);
+
+	err = epoll_wait(epfd, &ev, 1, 1000);
+	CHECK(err != 1 || ev.data.fd != cli_fd,
+	      "epoll_wait(cli_fd)", "err:%d errno:%d ev.data.fd:%d cli_fd:%d",
+	      err, errno, ev.data.fd, cli_fd);
+
+	err = recv(cli_fd, NULL, 0, MSG_TRUNC);
+	CHECK(err, "recv(cli_fd)", "err:%d errno:%d", err, errno);
+
+	close(epfd);
+	close(accept_fd);
+	close(cli_fd);
+
+	check_result();
+}
+
+int main(int argc, char **argv)
+{
+	struct bpf_prog_load_attr attr = {
+		.file = "test_sock_fields_kern.o",
+		.prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+		.expected_attach_type = BPF_CGROUP_INET_EGRESS,
+	};
+	int cgroup_fd, prog_fd, err;
+	struct bpf_object *obj;
+	struct bpf_map *map;
+
+	err = setup_cgroup_environment();
+	CHECK(err, "setup_cgroup_environment()", "err:%d errno:%d",
+	      err, errno);
+
+	atexit(cleanup_cgroup_environment);
+
+	/* Create a cgroup, get fd, and join it */
+	cgroup_fd = create_and_get_cgroup(TEST_CGROUP);
+	CHECK(cgroup_fd == -1, "create_and_get_cgroup()",
+	      "cgroup_fd:%d errno:%d", cgroup_fd, errno);
+
+	err = join_cgroup(TEST_CGROUP);
+	CHECK(err, "join_cgroup", "err:%d errno:%d", err, errno);
+
+	err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
+	CHECK(err, "bpf_prog_load_xattr()", "err:%d", err);
+
+	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_INET_EGRESS, 0);
+	CHECK(err == -1, "bpf_prog_attach(CPF_CGROUP_INET_EGRESS)",
+	      "err:%d errno%d", err, errno);
+	close(cgroup_fd);
+
+	map = bpf_object__find_map_by_name(obj, "addr_map");
+	CHECK(!map, "cannot find addr_map", "(null)");
+	addr_map_fd = bpf_map__fd(map);
+
+	map = bpf_object__find_map_by_name(obj, "sock_result_map");
+	CHECK(!map, "cannot find sock_result_map", "(null)");
+	sk_map_fd = bpf_map__fd(map);
+
+	map = bpf_object__find_map_by_name(obj, "tcp_sock_result_map");
+	CHECK(!map, "cannot find tcp_sock_result_map", "(null)");
+	tp_map_fd = bpf_map__fd(map);
+
+	map = bpf_object__find_map_by_name(obj, "linum_map");
+	CHECK(!map, "cannot find linum_map", "(null)");
+	linum_map_fd = bpf_map__fd(map);
+
+	test();
+
+	bpf_object__close(obj);
+	cleanup_cgroup_environment();
+
+	printf("PASS\n");
+
+	return 0;
+}

tools/testing/selftests/bpf/test_sock_fields_kern.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook */
+
+#include <linux/bpf.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+enum bpf_array_idx {
+	SRV_IDX,
+	CLI_IDX,
+	__NR_BPF_ARRAY_IDX,
+};
+
+struct bpf_map_def SEC("maps") addr_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(struct sockaddr_in6),
+	.max_entries = __NR_BPF_ARRAY_IDX,
+};
+
+struct bpf_map_def SEC("maps") sock_result_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(struct bpf_sock),
+	.max_entries = __NR_BPF_ARRAY_IDX,
+};
+
+struct bpf_map_def SEC("maps") tcp_sock_result_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(struct bpf_tcp_sock),
+	.max_entries = __NR_BPF_ARRAY_IDX,
+};
+
+struct bpf_map_def SEC("maps") linum_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+};
+
+static bool is_loopback6(__u32 *a6)
+{
+	return !a6[0] && !a6[1] && !a6[2] && a6[3] == bpf_htonl(1);
+}
+
+static void skcpy(struct bpf_sock *dst,
+		  const struct bpf_sock *src)
+{
+	dst->bound_dev_if = src->bound_dev_if;
+	dst->family = src->family;
+	dst->type = src->type;
+	dst->protocol = src->protocol;
+	dst->mark = src->mark;
+	dst->priority = src->priority;
+	dst->src_ip4 = src->src_ip4;
+	dst->src_ip6[0] = src->src_ip6[0];
+	dst->src_ip6[1] = src->src_ip6[1];
+	dst->src_ip6[2] = src->src_ip6[2];
+	dst->src_ip6[3] = src->src_ip6[3];
+	dst->src_port = src->src_port;
+	dst->dst_ip4 = src->dst_ip4;
+	dst->dst_ip6[0] = src->dst_ip6[0];
+	dst->dst_ip6[1] = src->dst_ip6[1];
+	dst->dst_ip6[2] = src->dst_ip6[2];
+	dst->dst_ip6[3] = src->dst_ip6[3];
+	dst->dst_port = src->dst_port;
+	dst->state = src->state;
+}
+
+static void tpcpy(struct bpf_tcp_sock *dst,
+		  const struct bpf_tcp_sock *src)
+{
+	dst->snd_cwnd = src->snd_cwnd;
+	dst->srtt_us = src->srtt_us;
+	dst->rtt_min = src->rtt_min;
+	dst->snd_ssthresh = src->snd_ssthresh;
+	dst->rcv_nxt = src->rcv_nxt;
+	dst->snd_nxt = src->snd_nxt;
+	dst->snd_una = src->snd_una;
+	dst->mss_cache = src->mss_cache;
+	dst->ecn_flags = src->ecn_flags;
+	dst->rate_delivered = src->rate_delivered;
+	dst->rate_interval_us = src->rate_interval_us;
+	dst->packets_out = src->packets_out;
+	dst->retrans_out = src->retrans_out;
+	dst->total_retrans = src->total_retrans;
+	dst->segs_in = src->segs_in;
+	dst->data_segs_in = src->data_segs_in;
+	dst->segs_out = src->segs_out;
+	dst->data_segs_out = src->data_segs_out;
+	dst->lost_out = src->lost_out;
+	dst->sacked_out = src->sacked_out;
+	dst->bytes_received = src->bytes_received;
+	dst->bytes_acked = src->bytes_acked;
+}
+
+#define RETURN {						\
+	linum = __LINE__;					\
+	bpf_map_update_elem(&linum_map, &idx0, &linum, 0);	\
+	return 1;						\
+}
+
+SEC("cgroup_skb/egress")
+int read_sock_fields(struct __sk_buff *skb)
+{
+	__u32 srv_idx = SRV_IDX, cli_idx = CLI_IDX, idx;
+	struct sockaddr_in6 *srv_sa6, *cli_sa6;
+	struct bpf_tcp_sock *tp, *tp_ret;
+	struct bpf_sock *sk, *sk_ret;
+	__u32 linum, idx0 = 0;
+
+	sk = skb->sk;
+	if (!sk || sk->state == 10)
+		RETURN;
+
+	sk = bpf_sk_fullsock(sk);
+	if (!sk || sk->family != AF_INET6 || sk->protocol != IPPROTO_TCP ||
+	    !is_loopback6(sk->src_ip6))
+		RETURN;
+
+	tp = bpf_tcp_sock(sk);
+	if (!tp)
+		RETURN;
+
+	srv_sa6 = bpf_map_lookup_elem(&addr_map, &srv_idx);
+	cli_sa6 = bpf_map_lookup_elem(&addr_map, &cli_idx);
+	if (!srv_sa6 || !cli_sa6)
+		RETURN;
+
+	if (sk->src_port == bpf_ntohs(srv_sa6->sin6_port))
+		idx = srv_idx;
+	else if (sk->src_port == bpf_ntohs(cli_sa6->sin6_port))
+		idx = cli_idx;
+	else
+		RETURN;
+
+	sk_ret = bpf_map_lookup_elem(&sock_result_map, &idx);
+	tp_ret = bpf_map_lookup_elem(&tcp_sock_result_map, &idx);
+	if (!sk_ret || !tp_ret)
+		RETURN;
+
+	skcpy(sk_ret, sk);
+	tpcpy(tp_ret, tp);
+
+	RETURN;
+}
+
+char _license[] SEC("license") = "GPL";