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
22 int
main(int argc,char * argv[])23 main(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