1/*	$OpenBSD: setresuid_effective_exec.c,v 1.3 2021/12/15 18:42:38 anton Exp $	*/
2/*
3 *	Written by Bret Stephen Lambert <blambert@openbsd.org> 2014
4 *	Public Domain.
5 */
6
7#include <sys/types.h>
8#include <sys/signal.h>
9#include <sys/proc.h>
10#include <sys/sysctl.h>
11#include <sys/wait.h>
12
13#include <err.h>
14#include <stdio.h>
15#include <stdlib.h>
16#include <string.h>
17#include <pwd.h>
18#include <unistd.h>
19
20#include "setuid_regress.h"
21
22int
23main(int argc, char *argv[])
24{
25	struct kinfo_proc	 kproc;
26	struct passwd		*pw;
27	char			*toexec = NULL;
28	uid_t			 uid;
29
30	if (argc > 1) {
31		argv ++;
32		if ((toexec = strdup(argv[0])) == NULL)
33			err(1, "strdup");
34	}
35
36	if ((pw = getpwnam(_SETUID_REGRESS_USER)) == NULL)
37		err(1, "unknown user \"%s\"", _SETUID_REGRESS_USER);
38
39	uid = getuid();
40
41	if (setresuid(-1, pw->pw_uid, -1) == -1)
42		err(1, "setuid");
43	checkuids(uid, pw->pw_uid, uid, "setuid");
44
45	/* should only respond to setuid upon exec */
46	if (issetugid())
47		errx(1, "process incorrectly as issetugid()");
48
49	if (read_kproc_pid(&kproc, getpid()) == -1)
50		err(1, "kproc read failed");
51
52	if (!(kproc.p_psflags & PS_SUGID))
53		errx(1, "PS_SUGID not set");
54	if (kproc.p_psflags & PS_SUGIDEXEC)
55		errx(1, "PS_SUGIDEXEC incorrectly set");
56
57	if (toexec != NULL)
58		if (execv(toexec, argv) == -1)
59			err(1, "exec of %s failed", toexec);
60	free(toexec);
61
62	exit(0);
63}
64