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/* test-uid.c --- playing with setuid.
* xscreensaver, Copyright (c) 1998, 2005 Jamie Zawinski <jwz@jwz.org>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
static void
print(void)
{
int uid = getuid();
int gid = getgid();
int euid = geteuid();
int egid = getegid();
struct passwd *p = 0;
struct group *g = 0;
gid_t groups[1024];
int n, size;
p = getpwuid (uid);
g = getgrgid (gid);
fprintf(stderr, "real user/group: %ld/%ld (%s/%s)\n", (long) uid, (long) gid,
(p && p->pw_name ? p->pw_name : "???"),
(g && g->gr_name ? g->gr_name : "???"));
p = getpwuid (euid);
g = getgrgid (egid);
fprintf(stderr, "eff. user/group: %ld/%ld (%s/%s)\n", (long)euid, (long)egid,
(p && p->pw_name ? p->pw_name : "???"),
(g && g->gr_name ? g->gr_name : "???"));
size = sizeof(groups) / sizeof(gid_t);
n = getgroups(size - 1, groups);
if (n < 0)
perror("getgroups failed");
else
{
int i;
fprintf (stderr, "eff. group list: [");
for (i = 0; i < n; i++)
{
g = getgrgid (groups[i]);
fprintf(stderr, "%s%s=%ld", (i == 0 ? "" : ", "),
(g->gr_name ? g->gr_name : "???"),
(long) groups[i]);
}
fprintf (stderr, "]\n");
}
}
int
main (int argc, char **argv)
{
int i;
struct passwd *p = 0;
struct group *g = 0;
if (argc <= 1)
{
fprintf(stderr,
"usage: %s [ user/group ... ]\n"
"\tEach argument may be a user name, or user/group.\n"
"\tThis program will attempt to setuid/setgid to each\n"
"\tin turn, and report the results. The user and group\n"
"\tnames may be strings, or numeric.\n",
argv[0]);
exit(1);
}
print();
for (i = 1; i < argc; i++)
{
char *user = argv[i];
char *group = strchr(user, '/');
if (!group)
group = strchr(user, '.');
if (group)
*group++ = 0;
if (group && *group)
{
long gid = 0;
int was_numeric = 0;
g = 0;
if (*group == '-' || (*group >= '0' && *group <= '9'))
if (1 == sscanf(group, "%ld", &gid))
{
g = getgrgid (gid);
was_numeric = 1;
}
if (!g)
g = getgrnam(group);
if (g)
{
gid = g->gr_gid;
group = g->gr_name;
}
else
{
if (was_numeric)
{
fprintf(stderr, "no group numbered %s.\n", group);
group = "";
}
else
{
fprintf(stderr, "no group named %s.\n", group);
goto NOGROUP;
}
}
fprintf(stderr, "setgroups(1, [%ld]) \"%s\"", gid, group);
{
gid_t g2 = gid;
if (setgroups(1, &g2) == 0)
fprintf(stderr, " succeeded.\n");
else
perror(" failed");
}
fprintf(stderr, "setgid(%ld) \"%s\"", gid, group);
if (setgid(gid) == 0)
fprintf(stderr, " succeeded.\n");
else
perror(" failed");
NOGROUP: ;
}
if (user && *user)
{
long uid = 0;
int was_numeric = 0;
p = 0;
if (*user == '-' || (*user >= '0' && *user <= '9'))
if (1 == sscanf(user, "%ld", &uid))
{
p = getpwuid (uid);
was_numeric = 1;
}
if (!p)
p = getpwnam(user);
if (p)
{
uid = p->pw_uid;
user = p->pw_name;
}
else
{
if (was_numeric)
{
fprintf(stderr, "no user numbered \"%s\".\n", user);
user = "";
}
else
{
fprintf(stderr, "no user named %s.\n", user);
goto NOUSER;
}
}
fprintf(stderr, "setuid(%ld) \"%s\"", uid, user);
if (setuid(uid) == 0)
fprintf(stderr, " succeeded.\n");
else
perror(" failed");
NOUSER: ;
}
print();
}
fprintf(stderr,
"running \"whoami\" and \"groups\" in a sub-process reports:\n");
fflush(stdout);
fflush(stderr);
system ("/bin/sh -c 'echo \"`whoami` / `groups`\"'");
fflush(stdout);
fflush(stderr);
exit(0);
}
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