1 /* $OpenBSD: syscallwx.c,v 1.2 2023/01/09 11:50:01 anton Exp $ */
2 /*
3 * Copyright (c) 2018 Todd Mortimer <mortimer@openbsd.org>
4 * Copyright (c) 2019 Alexander Bluhm <bluhm@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/mman.h>
20
21 #include <err.h>
22 #include <signal.h>
23 #include <string.h>
24 #include <unistd.h>
25
26 extern void gadget_getpid(void);
27 static void handler(int);
28
29 int
main(int argc,char * argv[])30 main(int argc, char *argv[])
31 {
32 union {
33 void *p;
34 void (*gadget)(void);
35 } addr;
36 int psz = getpagesize();
37
38 if (signal(SIGSEGV, handler) == SIG_ERR)
39 err(1, "signal");
40
41 addr.p = mmap(NULL, psz, PROT_READ | PROT_WRITE | PROT_EXEC,
42 MAP_PRIVATE | MAP_ANON, -1, 0);
43 if (addr.p == NULL)
44 err(1, "mmap");
45 memcpy(addr.p, gadget_getpid, psz);
46 addr.gadget();
47 return 3;
48 }
49
50 static void
handler(int signum)51 handler(int signum)
52 {
53 _exit(0);
54 }
55