Merge branch 'bpf-cgroup-bind-connect'

Andrey Ignatov says:

====================
v2->v3:
- rebase due to conflicts
- fix ipv6=m build

v1->v2:
- support expected_attach_type at prog load time so that prog (incl.
  context accesses and calls to helpers) can be validated with regard to
  specific attach point it is supposed to be attached to.
  Later, at attach time, attach type is checked so that it must be same as
  at load time if it was provided
- reworked hooks to rely on expected_attach_type, and reduced number of new
  prog types from 6 to just 1: BPF_PROG_TYPE_CGROUP_SOCK_ADDR
- reused BPF_PROG_TYPE_CGROUP_SOCK for sys_bind post-hooks
- add selftests for post-sys_bind hook

For our container management we've been using complicated and fragile setup
consisting of LD_PRELOAD wrapper intercepting bind and connect calls from
all containerized applications. Unfortunately it doesn't work for apps that
don't use glibc and changing all applications that run in the datacenter
is not possible due to 3rd party code and libraries (despite being
open source code) and sheer amount of legacy code that has to be rewritten
(we're rewriting what we can in parallel)

These applications are written without containers in mind and have
builtin assumptions about network services. Like an application X
expects to connect localhost:special_port and find service Y in there.
To move application X and service Y into two different containers
LD_PRELOAD approach is used to help one service connect to another
without rewriting them.
Moving these two applications into different L2 (netns) or L3 (vrf)
network isolation scopes doesn't help to solve the problem, since
applications need to see each other like they were running on
the host without containers.
So if app X and app Y would run in different netns something
would need to punch a connectivity hole in those namespaces.
That would be real layering violation (with corresponding
network debugging pains), since clean l2, l3 abstraction would
suddenly support something that breaks through the layers.

Instead we used LD_PRELOAD (and now bpf programs) at bind/connect
time to help applications discover and connect to each other.
All applications are running in init_nens and there are no vrfs.
After bind/connect the normal fib/neighbor core networking
logic works as it should always do and the whole system is
clean from network point of view and can be debugged with
standard tools.

We also considered resurrecting Hannes's afnetns work,
but all hierarchical namespace abstraction don't work due
to these builtin networking assumptions inside the apps.
To run an application inside cgroup container that was not written
with containers in mind we have to make an illusion of running
in non-containerized environment.
In some cases we remember the port and container id in the post-bind hook
in a bpf map and when some other task in a different container is trying
to connect to a service we need to know where this service is running.
It can be remote and can be local. Both client and service may or may not
be written with containers in mind and this sockaddr rewrite is providing
connectivity and load balancing feature.

BPF+cgroup looks to be the best solution for this problem.
Hence we introduce 3 hooks:
- at entry into sys_bind and sys_connect
  to let bpf prog look and modify 'struct sockaddr' provided
  by user space and fail bind/connect when appropriate
- post sys_bind after port is allocated

The approach works great and has zero overhead for anyone who doesn't
use it and very low overhead when deployed.

Different use case for this feature is to do low overhead firewall
that doesn't need to inspect all packets and works at bind/connect time.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 588 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c
new file mode 100644
index 000000000000..d488f20926e8
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sock_addr.c
@@ -0,0 +1,588 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <linux/filter.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "cgroup_helpers.h"
+
+#define CG_PATH	"/foo"
+#define CONNECT4_PROG_PATH	"./connect4_prog.o"
+#define CONNECT6_PROG_PATH	"./connect6_prog.o"
+
+#define SERV4_IP		"192.168.1.254"
+#define SERV4_REWRITE_IP	"127.0.0.1"
+#define SERV4_PORT		4040
+#define SERV4_REWRITE_PORT	4444
+
+#define SERV6_IP		"face:b00c:1234:5678::abcd"
+#define SERV6_REWRITE_IP	"::1"
+#define SERV6_PORT		6060
+#define SERV6_REWRITE_PORT	6666
+
+#define INET_NTOP_BUF	40
+
+typedef int (*load_fn)(enum bpf_attach_type, const char *comment);
+typedef int (*info_fn)(int, struct sockaddr *, socklen_t *);
+
+struct program {
+	enum bpf_attach_type type;
+	load_fn	loadfn;
+	int fd;
+	const char *name;
+	enum bpf_attach_type invalid_type;
+};
+
+char bpf_log_buf[BPF_LOG_BUF_SIZE];
+
+static int mk_sockaddr(int domain, const char *ip, unsigned short port,
+		       struct sockaddr *addr, socklen_t addr_len)
+{
+	struct sockaddr_in6 *addr6;
+	struct sockaddr_in *addr4;
+
+	if (domain != AF_INET && domain != AF_INET6) {
+		log_err("Unsupported address family");
+		return -1;
+	}
+
+	memset(addr, 0, addr_len);
+
+	if (domain == AF_INET) {
+		if (addr_len < sizeof(struct sockaddr_in))
+			return -1;
+		addr4 = (struct sockaddr_in *)addr;
+		addr4->sin_family = domain;
+		addr4->sin_port = htons(port);
+		if (inet_pton(domain, ip, (void *)&addr4->sin_addr) != 1) {
+			log_err("Invalid IPv4: %s", ip);
+			return -1;
+		}
+	} else if (domain == AF_INET6) {
+		if (addr_len < sizeof(struct sockaddr_in6))
+			return -1;
+		addr6 = (struct sockaddr_in6 *)addr;
+		addr6->sin6_family = domain;
+		addr6->sin6_port = htons(port);
+		if (inet_pton(domain, ip, (void *)&addr6->sin6_addr) != 1) {
+			log_err("Invalid IPv6: %s", ip);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static int load_insns(enum bpf_attach_type attach_type,
+		      const struct bpf_insn *insns, size_t insns_cnt,
+		      const char *comment)
+{
+	struct bpf_load_program_attr load_attr;
+	int ret;
+
+	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
+	load_attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR;
+	load_attr.expected_attach_type = attach_type;
+	load_attr.insns = insns;
+	load_attr.insns_cnt = insns_cnt;
+	load_attr.license = "GPL";
+
+	ret = bpf_load_program_xattr(&load_attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
+	if (ret < 0 && comment) {
+		log_err(">>> Loading %s program error.\n"
+			">>> Output from verifier:\n%s\n-------\n",
+			comment, bpf_log_buf);
+	}
+
+	return ret;
+}
+
+/* [1] These testing programs try to read different context fields, including
+ * narrow loads of different sizes from user_ip4 and user_ip6, and write to
+ * those allowed to be overridden.
+ *
+ * [2] BPF_LD_IMM64 & BPF_JMP_REG are used below whenever there is a need to
+ * compare a register with unsigned 32bit integer. BPF_JMP_IMM can't be used
+ * in such cases since it accepts only _signed_ 32bit integer as IMM
+ * argument. Also note that BPF_LD_IMM64 contains 2 instructions what matters
+ * to count jumps properly.
+ */
+
+static int bind4_prog_load(enum bpf_attach_type attach_type,
+			   const char *comment)
+{
+	union {
+		uint8_t u4_addr8[4];
+		uint16_t u4_addr16[2];
+		uint32_t u4_addr32;
+	} ip4;
+	struct sockaddr_in addr4_rw;
+
+	if (inet_pton(AF_INET, SERV4_IP, (void *)&ip4) != 1) {
+		log_err("Invalid IPv4: %s", SERV4_IP);
+		return -1;
+	}
+
+	if (mk_sockaddr(AF_INET, SERV4_REWRITE_IP, SERV4_REWRITE_PORT,
+			(struct sockaddr *)&addr4_rw, sizeof(addr4_rw)) == -1)
+		return -1;
+
+	/* See [1]. */
+	struct bpf_insn insns[] = {
+		BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+		/* if (sk.family == AF_INET && */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, family)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, AF_INET, 16),
+
+		/*     (sk.type == SOCK_DGRAM || sk.type == SOCK_STREAM) && */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, type)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, SOCK_DGRAM, 1),
+		BPF_JMP_A(1),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, SOCK_STREAM, 12),
+
+		/*     1st_byte_of_user_ip4 == expected && */
+		BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, user_ip4)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr8[0], 10),
+
+		/*     1st_half_of_user_ip4 == expected && */
+		BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, user_ip4)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip4.u4_addr16[0], 8),
+
+		/*     whole_user_ip4 == expected) { */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, user_ip4)),
+		BPF_LD_IMM64(BPF_REG_8, ip4.u4_addr32), /* See [2]. */
+		BPF_JMP_REG(BPF_JNE, BPF_REG_7, BPF_REG_8, 4),
+
+		/*      user_ip4 = addr4_rw.sin_addr */
+		BPF_MOV32_IMM(BPF_REG_7, addr4_rw.sin_addr.s_addr),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, user_ip4)),
+
+		/*      user_port = addr4_rw.sin_port */
+		BPF_MOV32_IMM(BPF_REG_7, addr4_rw.sin_port),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, user_port)),
+		/* } */
+
+		/* return 1 */
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_EXIT_INSN(),
+	};
+
+	return load_insns(attach_type, insns,
+			  sizeof(insns) / sizeof(struct bpf_insn), comment);
+}
+
+static int bind6_prog_load(enum bpf_attach_type attach_type,
+			   const char *comment)
+{
+	struct sockaddr_in6 addr6_rw;
+	struct in6_addr ip6;
+
+	if (inet_pton(AF_INET6, SERV6_IP, (void *)&ip6) != 1) {
+		log_err("Invalid IPv6: %s", SERV6_IP);
+		return -1;
+	}
+
+	if (mk_sockaddr(AF_INET6, SERV6_REWRITE_IP, SERV6_REWRITE_PORT,
+			(struct sockaddr *)&addr6_rw, sizeof(addr6_rw)) == -1)
+		return -1;
+
+	/* See [1]. */
+	struct bpf_insn insns[] = {
+		BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+		/* if (sk.family == AF_INET6 && */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, family)),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, AF_INET6, 18),
+
+		/*            5th_byte_of_user_ip6 == expected && */
+		BPF_LDX_MEM(BPF_B, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, user_ip6[1])),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip6.s6_addr[4], 16),
+
+		/*            3rd_half_of_user_ip6 == expected && */
+		BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, user_ip6[1])),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_7, ip6.s6_addr16[2], 14),
+
+		/*            last_word_of_user_ip6 == expected) { */
+		BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+			    offsetof(struct bpf_sock_addr, user_ip6[3])),
+		BPF_LD_IMM64(BPF_REG_8, ip6.s6_addr32[3]),  /* See [2]. */
+		BPF_JMP_REG(BPF_JNE, BPF_REG_7, BPF_REG_8, 10),
+
+
+#define STORE_IPV6_WORD(N)						       \
+		BPF_MOV32_IMM(BPF_REG_7, addr6_rw.sin6_addr.s6_addr32[N]),     \
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,		       \
+			    offsetof(struct bpf_sock_addr, user_ip6[N]))
+
+		/*      user_ip6 = addr6_rw.sin6_addr */
+		STORE_IPV6_WORD(0),
+		STORE_IPV6_WORD(1),
+		STORE_IPV6_WORD(2),
+		STORE_IPV6_WORD(3),
+
+		/*      user_port = addr6_rw.sin6_port */
+		BPF_MOV32_IMM(BPF_REG_7, addr6_rw.sin6_port),
+		BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_7,
+			    offsetof(struct bpf_sock_addr, user_port)),
+
+		/* } */
+
+		/* return 1 */
+		BPF_MOV64_IMM(BPF_REG_0, 1),
+		BPF_EXIT_INSN(),
+	};
+
+	return load_insns(attach_type, insns,
+			  sizeof(insns) / sizeof(struct bpf_insn), comment);
+}
+
+static int connect_prog_load_path(const char *path,
+				  enum bpf_attach_type attach_type,
+				  const char *comment)
+{
+	struct bpf_prog_load_attr attr;
+	struct bpf_object *obj;
+	int prog_fd;
+
+	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
+	attr.file = path;
+	attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR;
+	attr.expected_attach_type = attach_type;
+
+	if (bpf_prog_load_xattr(&attr, &obj, &prog_fd)) {
+		if (comment)
+			log_err(">>> Loading %s program at %s error.\n",
+				comment, path);
+		return -1;
+	}
+
+	return prog_fd;
+}
+
+static int connect4_prog_load(enum bpf_attach_type attach_type,
+			      const char *comment)
+{
+	return connect_prog_load_path(CONNECT4_PROG_PATH, attach_type, comment);
+}
+
+static int connect6_prog_load(enum bpf_attach_type attach_type,
+			      const char *comment)
+{
+	return connect_prog_load_path(CONNECT6_PROG_PATH, attach_type, comment);
+}
+
+static void print_ip_port(int sockfd, info_fn fn, const char *fmt)
+{
+	char addr_buf[INET_NTOP_BUF];
+	struct sockaddr_storage addr;
+	struct sockaddr_in6 *addr6;
+	struct sockaddr_in *addr4;
+	socklen_t addr_len;
+	unsigned short port;
+	void *nip;
+
+	addr_len = sizeof(struct sockaddr_storage);
+	memset(&addr, 0, addr_len);
+
+	if (fn(sockfd, (struct sockaddr *)&addr, (socklen_t *)&addr_len) == 0) {
+		if (addr.ss_family == AF_INET) {
+			addr4 = (struct sockaddr_in *)&addr;
+			nip = (void *)&addr4->sin_addr;
+			port = ntohs(addr4->sin_port);
+		} else if (addr.ss_family == AF_INET6) {
+			addr6 = (struct sockaddr_in6 *)&addr;
+			nip = (void *)&addr6->sin6_addr;
+			port = ntohs(addr6->sin6_port);
+		} else {
+			return;
+		}
+		const char *addr_str =
+			inet_ntop(addr.ss_family, nip, addr_buf, INET_NTOP_BUF);
+		printf(fmt, addr_str ? addr_str : "??", port);
+	}
+}
+
+static void print_local_ip_port(int sockfd, const char *fmt)
+{
+	print_ip_port(sockfd, getsockname, fmt);
+}
+
+static void print_remote_ip_port(int sockfd, const char *fmt)
+{
+	print_ip_port(sockfd, getpeername, fmt);
+}
+
+static int start_server(int type, const struct sockaddr_storage *addr,
+			socklen_t addr_len)
+{
+
+	int fd;
+
+	fd = socket(addr->ss_family, type, 0);
+	if (fd == -1) {
+		log_err("Failed to create server socket");
+		goto out;
+	}
+
+	if (bind(fd, (const struct sockaddr *)addr, addr_len) == -1) {
+		log_err("Failed to bind server socket");
+		goto close_out;
+	}
+
+	if (type == SOCK_STREAM) {
+		if (listen(fd, 128) == -1) {
+			log_err("Failed to listen on server socket");
+			goto close_out;
+		}
+	}
+
+	print_local_ip_port(fd, "\t   Actual: bind(%s, %d)\n");
+
+	goto out;
+close_out:
+	close(fd);
+	fd = -1;
+out:
+	return fd;
+}
+
+static int connect_to_server(int type, const struct sockaddr_storage *addr,
+			     socklen_t addr_len)
+{
+	int domain;
+	int fd;
+
+	domain = addr->ss_family;
+
+	if (domain != AF_INET && domain != AF_INET6) {
+		log_err("Unsupported address family");
+		return -1;
+	}
+
+	fd = socket(domain, type, 0);
+	if (fd == -1) {
+		log_err("Failed to creating client socket");
+		return -1;
+	}
+
+	if (connect(fd, (const struct sockaddr *)addr, addr_len) == -1) {
+		log_err("Fail to connect to server");
+		goto err;
+	}
+
+	print_remote_ip_port(fd, "\t   Actual: connect(%s, %d)");
+	print_local_ip_port(fd, " from (%s, %d)\n");
+
+	return 0;
+err:
+	close(fd);
+	return -1;
+}
+
+static void print_test_case_num(int domain, int type)
+{
+	static int test_num;
+
+	printf("Test case #%d (%s/%s):\n", ++test_num,
+	       (domain == AF_INET ? "IPv4" :
+		domain == AF_INET6 ? "IPv6" :
+		"unknown_domain"),
+	       (type == SOCK_STREAM ? "TCP" :
+		type == SOCK_DGRAM ? "UDP" :
+		"unknown_type"));
+}
+
+static int run_test_case(int domain, int type, const char *ip,
+			 unsigned short port)
+{
+	struct sockaddr_storage addr;
+	socklen_t addr_len = sizeof(addr);
+	int servfd = -1;
+	int err = 0;
+
+	print_test_case_num(domain, type);
+
+	if (mk_sockaddr(domain, ip, port, (struct sockaddr *)&addr,
+			addr_len) == -1)
+		return -1;
+
+	printf("\tRequested: bind(%s, %d) ..\n", ip, port);
+	servfd = start_server(type, &addr, addr_len);
+	if (servfd == -1)
+		goto err;
+
+	printf("\tRequested: connect(%s, %d) from (*, *) ..\n", ip, port);
+	if (connect_to_server(type, &addr, addr_len))
+		goto err;
+
+	goto out;
+err:
+	err = -1;
+out:
+	close(servfd);
+	return err;
+}
+
+static void close_progs_fds(struct program *progs, size_t prog_cnt)
+{
+	size_t i;
+
+	for (i = 0; i < prog_cnt; ++i) {
+		close(progs[i].fd);
+		progs[i].fd = -1;
+	}
+}
+
+static int load_and_attach_progs(int cgfd, struct program *progs,
+				 size_t prog_cnt)
+{
+	size_t i;
+
+	for (i = 0; i < prog_cnt; ++i) {
+		printf("Load %s with invalid type (can pollute stderr) ",
+		       progs[i].name);
+		fflush(stdout);
+		progs[i].fd = progs[i].loadfn(progs[i].invalid_type, NULL);
+		if (progs[i].fd != -1) {
+			log_err("Load with invalid type accepted for %s",
+				progs[i].name);
+			goto err;
+		}
+		printf("... REJECTED\n");
+
+		printf("Load %s with valid type", progs[i].name);
+		progs[i].fd = progs[i].loadfn(progs[i].type, progs[i].name);
+		if (progs[i].fd == -1) {
+			log_err("Failed to load program %s", progs[i].name);
+			goto err;
+		}
+		printf(" ... OK\n");
+
+		printf("Attach %s with invalid type", progs[i].name);
+		if (bpf_prog_attach(progs[i].fd, cgfd, progs[i].invalid_type,
+				    BPF_F_ALLOW_OVERRIDE) != -1) {
+			log_err("Attach with invalid type accepted for %s",
+				progs[i].name);
+			goto err;
+		}
+		printf(" ... REJECTED\n");
+
+		printf("Attach %s with valid type", progs[i].name);
+		if (bpf_prog_attach(progs[i].fd, cgfd, progs[i].type,
+				    BPF_F_ALLOW_OVERRIDE) == -1) {
+			log_err("Failed to attach program %s", progs[i].name);
+			goto err;
+		}
+		printf(" ... OK\n");
+	}
+
+	return 0;
+err:
+	close_progs_fds(progs, prog_cnt);
+	return -1;
+}
+
+static int run_domain_test(int domain, int cgfd, struct program *progs,
+			   size_t prog_cnt, const char *ip, unsigned short port)
+{
+	int err = 0;
+
+	if (load_and_attach_progs(cgfd, progs, prog_cnt) == -1)
+		goto err;
+
+	if (run_test_case(domain, SOCK_STREAM, ip, port) == -1)
+		goto err;
+
+	if (run_test_case(domain, SOCK_DGRAM, ip, port) == -1)
+		goto err;
+
+	goto out;
+err:
+	err = -1;
+out:
+	close_progs_fds(progs, prog_cnt);
+	return err;
+}
+
+static int run_test(void)
+{
+	size_t inet6_prog_cnt;
+	size_t inet_prog_cnt;
+	int cgfd = -1;
+	int err = 0;
+
+	struct program inet6_progs[] = {
+		{BPF_CGROUP_INET6_BIND, bind6_prog_load, -1, "bind6",
+		 BPF_CGROUP_INET4_BIND},
+		{BPF_CGROUP_INET6_CONNECT, connect6_prog_load, -1, "connect6",
+		 BPF_CGROUP_INET4_CONNECT},
+	};
+	inet6_prog_cnt = sizeof(inet6_progs) / sizeof(struct program);
+
+	struct program inet_progs[] = {
+		{BPF_CGROUP_INET4_BIND, bind4_prog_load, -1, "bind4",
+		 BPF_CGROUP_INET6_BIND},
+		{BPF_CGROUP_INET4_CONNECT, connect4_prog_load, -1, "connect4",
+		 BPF_CGROUP_INET6_CONNECT},
+	};
+	inet_prog_cnt = sizeof(inet_progs) / sizeof(struct program);
+
+	if (setup_cgroup_environment())
+		goto err;
+
+	cgfd = create_and_get_cgroup(CG_PATH);
+	if (!cgfd)
+		goto err;
+
+	if (join_cgroup(CG_PATH))
+		goto err;
+
+	if (run_domain_test(AF_INET, cgfd, inet_progs, inet_prog_cnt, SERV4_IP,
+			    SERV4_PORT) == -1)
+		goto err;
+
+	if (run_domain_test(AF_INET6, cgfd, inet6_progs, inet6_prog_cnt,
+			    SERV6_IP, SERV6_PORT) == -1)
+		goto err;
+
+	goto out;
+err:
+	err = -1;
+out:
+	close(cgfd);
+	cleanup_cgroup_environment();
+	printf(err ? "### FAIL\n" : "### SUCCESS\n");
+	return err;
+}
+
+int main(int argc, char **argv)
+{
+	if (argc < 2) {
+		fprintf(stderr,
+			"%s has to be run via %s.sh. Skip direct run.\n",
+			argv[0], argv[0]);
+		exit(0);
+	}
+	return run_test();
+}