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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <AK/Vector.h>
28#include <alloca.h>
29#include <grp.h>
30#include <pwd.h>
31#include <stdio.h>
32#include <string.h>
33#include <unistd.h>
34
35extern "C" int main(int, char**);
36
37int main(int argc, char** argv)
38{
39 uid_t uid = 0;
40 gid_t gid = 0;
41 struct passwd* pwd = nullptr;
42 if (argc > 1) {
43 pwd = getpwnam(argv[1]);
44 if (!pwd) {
45 fprintf(stderr, "No such user: %s\n", argv[1]);
46 return 1;
47 }
48 uid = pwd->pw_uid;
49 gid = pwd->pw_gid;
50 }
51
52 if (!pwd)
53 pwd = getpwuid(0);
54
55 if (!pwd) {
56 fprintf(stderr, "No passwd entry.\n");
57 return 1;
58 }
59
60 Vector<gid_t> extra_gids;
61 for (auto* group = getgrent(); group; group = getgrent()) {
62 for (size_t i = 0; group->gr_mem[i]; ++i) {
63 if (!strcmp(pwd->pw_name, group->gr_mem[i]))
64 extra_gids.append(group->gr_gid);
65 }
66 }
67 endgrent();
68
69 int rc = setgroups(extra_gids.size(), extra_gids.data());
70 if (rc < 0) {
71 perror("setgroups");
72 return 1;
73 }
74 rc = setgid(gid);
75 if (rc < 0) {
76 perror("setgid");
77 return 1;
78 }
79 rc = setuid(uid);
80 if (rc < 0) {
81 perror("setuid");
82 return 1;
83 }
84 rc = execl("/bin/sh", "sh", nullptr);
85 perror("execl");
86 return 1;
87}