#define _GNU_SOURCE

#include <sys/syscall.h>
#include <unistd.h>
#include <pthread.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <time.h>
#include <sys/prctl.h>
#include <dirent.h>
#include <sys/mount.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_tun.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/if_arp.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/uio.h>

__attribute__((noreturn)) static void doexit(int status)
{
	volatile unsigned i;
	syscall(__NR_exit_group, status);
	for (i = 0;; i++) {
	}
}

#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <setjmp.h>
#include <signal.h>
#include <string.h>

const int kFailStatus = 67;
const int kRetryStatus = 69;

 static void fail(const char* msg, ...)
{
	int e = errno;
	va_list args;
	va_start(args, msg);
	vfprintf(stderr, msg, args);
	va_end(args);
	fprintf(stderr, " (errno %d)\n", e);
	doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
}

 static void exitf(const char* msg, ...)
{
	int e = errno;
	va_list args;
	va_start(args, msg);
	vfprintf(stderr, msg, args);
	va_end(args);
	fprintf(stderr, " (errno %d)\n", e);
	doexit(kRetryStatus);
}

static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
	uintptr_t addr = (uintptr_t)info->si_addr;
	const uintptr_t prog_start = 1 << 20;
	const uintptr_t prog_end = 100 << 20;
	if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) && (addr < prog_start || addr > prog_end)) {
		_longjmp(segv_env, 1);
	}
	doexit(sig);
	for (;;) {
	}
}

static void install_segv_handler()
{
	struct sigaction sa;

	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = SIG_IGN;
	syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
	syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);

	memset(&sa, 0, sizeof(sa));
	sa.sa_sigaction = segv_handler;
	sa.sa_flags = SA_NODEFER | SA_SIGINFO;
	sigaction(SIGSEGV, &sa, NULL);
	sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...) { __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); if (_setjmp(segv_env) == 0) { __VA_ARGS__; } __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); }

static uint64_t current_time_ms()
{
	struct timespec ts;

	if (clock_gettime(CLOCK_MONOTONIC, &ts))
		fail("clock_gettime failed");
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static void use_temporary_dir()
{
	char tmpdir_template[] = "./syzkaller.XXXXXX";
	char* tmpdir = mkdtemp(tmpdir_template);
	if (!tmpdir)
		fail("failed to mkdtemp");
	if (chmod(tmpdir, 0777))
		fail("failed to chmod");
	if (chdir(tmpdir))
		fail("failed to chdir");
}

static void vsnprintf_check(char* str, size_t size, const char* format, va_list args)
{
	int rv;

	rv = vsnprintf(str, size, format, args);
	if (rv < 0)
		fail("tun: snprintf failed");
	if ((size_t)rv >= size)
		fail("tun: string '%s...' doesn't fit into buffer", str);
}

static void snprintf_check(char* str, size_t size, const char* format, ...)
{
	va_list args;

	va_start(args, format);
	vsnprintf_check(str, size, format, args);
	va_end(args);
}

#define COMMAND_MAX_LEN 128
#define PATH_PREFIX "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin "
#define PATH_PREFIX_LEN (sizeof(PATH_PREFIX) - 1)

static void execute_command(const char* format, ...)
{
	va_list args;
	char command[PATH_PREFIX_LEN + COMMAND_MAX_LEN];
	int rv;

	va_start(args, format);
	memcpy(command, PATH_PREFIX, PATH_PREFIX_LEN);
	vsnprintf_check(command + PATH_PREFIX_LEN, COMMAND_MAX_LEN, format, args);
	rv = system(command);
	if (rv != 0)
		fail("tun: command \"%s\" failed with code %d", &command[0], rv);

	va_end(args);
}

static int tunfd = -1;
static int tun_frags_enabled;

#define SYZ_TUN_MAX_PACKET_SIZE 1000

#define MAX_PIDS 32
#define ADDR_MAX_LEN 32

#define LOCAL_MAC "aa:aa:aa:aa:aa:%02hx"
#define REMOTE_MAC "bb:bb:bb:bb:bb:%02hx"

#define LOCAL_IPV4 "172.20.%d.170"
#define REMOTE_IPV4 "172.20.%d.187"

#define LOCAL_IPV6 "fe80::%02hxaa"
#define REMOTE_IPV6 "fe80::%02hxbb"

#define IFF_NAPI 0x0010
#define IFF_NAPI_FRAGS 0x0020

static void initialize_tun(uint64_t pid)
{
	if (pid >= MAX_PIDS)
		fail("tun: no more than %d executors", MAX_PIDS);
	int id = pid;

	tunfd = open("/dev/net/tun", O_RDWR | O_NONBLOCK);
	if (tunfd == -1) {
		printf("tun: can't open /dev/net/tun: please enable CONFIG_TUN=y\n");
		printf("otherwise fuzzing or reproducing might not work as intended\n");
		return;
	}

	char iface[IFNAMSIZ];
	snprintf_check(iface, sizeof(iface), "syz%d", id);

	struct ifreq ifr;
	memset(&ifr, 0, sizeof(ifr));
	strncpy(ifr.ifr_name, iface, IFNAMSIZ);
	ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_NAPI | IFF_NAPI_FRAGS;
	if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0) {
		ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
		if (ioctl(tunfd, TUNSETIFF, (void*)&ifr) < 0)
			fail("tun: ioctl(TUNSETIFF) failed");
	}
	if (ioctl(tunfd, TUNGETIFF, (void*)&ifr) < 0)
		fail("tun: ioctl(TUNGETIFF) failed");
	tun_frags_enabled = (ifr.ifr_flags & IFF_NAPI_FRAGS) != 0;

	char local_mac[ADDR_MAX_LEN];
	snprintf_check(local_mac, sizeof(local_mac), LOCAL_MAC, id);
	char remote_mac[ADDR_MAX_LEN];
	snprintf_check(remote_mac, sizeof(remote_mac), REMOTE_MAC, id);

	char local_ipv4[ADDR_MAX_LEN];
	snprintf_check(local_ipv4, sizeof(local_ipv4), LOCAL_IPV4, id);
	char remote_ipv4[ADDR_MAX_LEN];
	snprintf_check(remote_ipv4, sizeof(remote_ipv4), REMOTE_IPV4, id);

	char local_ipv6[ADDR_MAX_LEN];
	snprintf_check(local_ipv6, sizeof(local_ipv6), LOCAL_IPV6, id);
	char remote_ipv6[ADDR_MAX_LEN];
	snprintf_check(remote_ipv6, sizeof(remote_ipv6), REMOTE_IPV6, id);

	execute_command("sysctl -w net.ipv6.conf.%s.accept_dad=0", iface);

	execute_command("sysctl -w net.ipv6.conf.%s.router_solicitations=0", iface);

	execute_command("ip link set dev %s address %s", iface, local_mac);
	execute_command("ip addr add %s/24 dev %s", local_ipv4, iface);
	execute_command("ip -6 addr add %s/120 dev %s", local_ipv6, iface);
	execute_command("ip neigh add %s lladdr %s dev %s nud permanent", remote_ipv4, remote_mac, iface);
	execute_command("ip -6 neigh add %s lladdr %s dev %s nud permanent", remote_ipv6, remote_mac, iface);
	execute_command("ip link set dev %s up", iface);
}

static void setup_tun(uint64_t pid, bool enable_tun)
{
	if (enable_tun)
		initialize_tun(pid);
}

static int read_tun(char* data, int size)
{
	if (tunfd < 0)
		return -1;

	int rv = read(tunfd, data, size);
	if (rv < 0) {
		if (errno == EAGAIN)
			return -1;
		if (errno == EBADFD)
			return -1;
		fail("tun: read failed with %d", rv);
	}
	return rv;
}

static void flush_tun()
{
	char data[SYZ_TUN_MAX_PACKET_SIZE];
	while (read_tun(&data[0], sizeof(data)) != -1)
		;
}

static void remove_dir(const char* dir)
{
	DIR* dp;
	struct dirent* ep;
	int iter = 0;
retry:
	dp = opendir(dir);
	if (dp == NULL) {
		if (errno == EMFILE) {
			exitf("opendir(%s) failed due to NOFILE, exiting");
		}
		exitf("opendir(%s) failed", dir);
	}
	while ((ep = readdir(dp))) {
		if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0)
			continue;
		char filename[FILENAME_MAX];
		snprintf(filename, sizeof(filename), "%s/%s", dir, ep->d_name);
		struct stat st;
		if (lstat(filename, &st))
			exitf("lstat(%s) failed", filename);
		if (S_ISDIR(st.st_mode)) {
			remove_dir(filename);
			continue;
		}
		int i;
		for (i = 0;; i++) {
			if (unlink(filename) == 0)
				break;
			if (errno == EROFS) {
				break;
			}
			if (errno != EBUSY || i > 100)
				exitf("unlink(%s) failed", filename);
			if (umount2(filename, MNT_DETACH))
				exitf("umount(%s) failed", filename);
		}
	}
	closedir(dp);
	int i;
	for (i = 0;; i++) {
		if (rmdir(dir) == 0)
			break;
		if (i < 100) {
			if (errno == EROFS) {
				break;
			}
			if (errno == EBUSY) {
				if (umount2(dir, MNT_DETACH))
					exitf("umount(%s) failed", dir);
				continue;
			}
			if (errno == ENOTEMPTY) {
				if (iter < 100) {
					iter++;
					goto retry;
				}
			}
		}
		exitf("rmdir(%s) failed", dir);
	}
}

static void test();

void loop()
{
	int iter;
	for (iter = 0;; iter++) {
		char cwdbuf[256];
		sprintf(cwdbuf, "./%d", iter);
		if (mkdir(cwdbuf, 0777))
			fail("failed to mkdir");
		int pid = fork();
		if (pid < 0)
			fail("clone failed");
		if (pid == 0) {
			prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
			setpgrp();
			if (chdir(cwdbuf))
				fail("failed to chdir");
			flush_tun();
			test();
			doexit(0);
		}
		int status = 0;
		uint64_t start = current_time_ms();
		for (;;) {
			int res = waitpid(-1, &status, __WALL | WNOHANG);
			if (res == pid)
				break;
			usleep(1000);
			if (current_time_ms() - start > 5 * 1000) {
				kill(-pid, SIGKILL);
				kill(pid, SIGKILL);
				while (waitpid(-1, &status, __WALL) != pid) {
				}
				break;
			}
		}
		remove_dir(cwdbuf);
	}
}

long r[5];
void *thr(void *arg)
{
	switch ((long)arg) {
	case 0:
		r[0] = syscall(__NR_mmap, 0x20000000ul, 0xb4c000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul);
		break;
	case 1:
		r[1] = syscall(__NR_socket, 0xaul, 0x1ul, 0x0ul);
		break;
	case 2:
		NONFAILING(*(uint32_t*)0x204feffc = (uint32_t)0x100000807);
		r[3] = syscall(__NR_setsockopt, r[1], 0x29ul, 0xd1ul, 0x204feffcul, 0x4ul);
		break;
	case 3:
		r[4] = syscall(__NR_listen, r[1], 0x3ul);
		break;
	}
	return 0;
}

void test()
{
	long i;
	pthread_t th[8];

	memset(r, -1, sizeof(r));
	for (i = 0; i < 4; i++) {
		pthread_create(&th[i], 0, thr, (void*)i);
		usleep(rand()%10000);
	}
	usleep(rand()%100000);
}

int main()
{
	int i;	for (i = 0; i < 8; i++) {
		if (fork() == 0) {
			install_segv_handler();
			use_temporary_dir();
			setup_tun(i, true);
			loop();
			return 0;
		}
	}
	sleep(1000000);
	return 0;
}