1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) Linux Test Project, 2001-2021
4 * Copyright (c) International Business Machines Corp., 2001
5 * 07/2001 Ported by Wayne Boyer
6 */
7
8 /*\
9 * [Description]
10 *
11 * Verify that, fchown(2) succeeds to change the group of a file specified
12 * by path when called by non-root user with the following constraints:
13 *
14 * - euid of the process is equal to the owner of the file
15 * - the intended gid is either egid, or one of the supplementary gids
16 * of the process.
17 *
18 * Also verify that fchown() clears the setuid/setgid bits set on the file.
19 */
20
21 #include <grp.h>
22 #include <pwd.h>
23 #include <fcntl.h>
24 #include <sys/stat.h>
25 #include <sys/types.h>
26
27 #include "tst_test.h"
28 #include "compat_tst_16.h"
29
30 #define FILE_MODE (S_IFREG|S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)
31 #define NEW_PERMS (S_IFREG|S_IRWXU|S_IRWXG|S_ISUID|S_ISGID)
32 #define FILENAME "fchown03_testfile"
33
34 static int fd;
35 static struct passwd *ltpuser;
36
check_owner(struct stat * s,uid_t exp_uid,gid_t exp_gid)37 static void check_owner(struct stat *s, uid_t exp_uid, gid_t exp_gid)
38 {
39 if (s->st_uid != exp_uid || s->st_gid != exp_gid)
40 tst_res(TFAIL, "%s: wrong owner set to (uid=%d, gid=%d), expected (uid=%d, gid=%d)",
41 FILENAME, s->st_uid, s->st_gid, exp_uid, exp_gid);
42 }
43
check_mode(struct stat * s,mode_t exp_mode)44 static void check_mode(struct stat *s, mode_t exp_mode)
45 {
46 if (s->st_mode != exp_mode)
47 tst_res(TFAIL, "%s: wrong mode permissions %#o, expected %#o",
48 FILENAME, s->st_mode, exp_mode);
49 }
50
run(void)51 static void run(void)
52 {
53 uid_t uid;
54 gid_t gid;
55 struct stat stat_buf;
56
57 SAFE_SETEUID(0);
58 SAFE_FCHOWN(fd, -1, 0);
59 SAFE_FCHMOD(fd, NEW_PERMS);
60 SAFE_SETEUID(ltpuser->pw_uid);
61
62 UID16_CHECK((uid = geteuid()), "fchown");
63 GID16_CHECK((gid = getegid()), "fchown");
64
65 SAFE_STAT(FILENAME, &stat_buf);
66 check_owner(&stat_buf, uid, 0);
67 check_mode(&stat_buf, NEW_PERMS);
68
69 TST_EXP_PASS(FCHOWN(fd, -1, gid), "fchown(fd, %d, %d)", -1, gid);
70 SAFE_STAT(FILENAME, &stat_buf);
71 check_owner(&stat_buf, uid, gid);
72 check_mode(&stat_buf, NEW_PERMS & ~(S_ISUID | S_ISGID));
73 }
74
setup(void)75 static void setup(void)
76 {
77 ltpuser = SAFE_GETPWNAM("nobody");
78 SAFE_SETEGID(ltpuser->pw_gid);
79 SAFE_SETEUID(ltpuser->pw_uid);
80
81 fd = SAFE_OPEN(FILENAME, O_RDWR | O_CREAT, FILE_MODE);
82 }
83
cleanup(void)84 static void cleanup(void)
85 {
86 SAFE_SETEGID(0);
87 SAFE_SETEUID(0);
88
89 if (fd > 0)
90 SAFE_CLOSE(fd);
91 }
92
93 static struct tst_test test = {
94 .needs_root = 1,
95 .needs_tmpdir = 1,
96 .setup = setup,
97 .cleanup = cleanup,
98 .test_all = run,
99 };
100