1// SPDX-License-Identifier: GPL-2.0-or-later
2
3#define _GNU_SOURCE
4#include <fcntl.h>
5#include <sys/stat.h>
6#include <sys/types.h>
7#include <syscall.h>
8#include <unistd.h>
9
10#include "../kselftest.h"
11
12int sys_fchmodat2(int dfd, const char *filename, mode_t mode, int flags)
13{
14	int ret = syscall(__NR_fchmodat2, dfd, filename, mode, flags);
15
16	return ret >= 0 ? ret : -errno;
17}
18
19int setup_testdir(void)
20{
21	int dfd, ret;
22	char dirname[] = "/tmp/ksft-fchmodat2.XXXXXX";
23
24	/* Make the top-level directory. */
25	if (!mkdtemp(dirname))
26		ksft_exit_fail_msg("%s: failed to create tmpdir\n", __func__);
27
28	dfd = open(dirname, O_PATH | O_DIRECTORY);
29	if (dfd < 0)
30		ksft_exit_fail_msg("%s: failed to open tmpdir\n", __func__);
31
32	ret = openat(dfd, "regfile", O_CREAT | O_WRONLY | O_TRUNC, 0644);
33	if (ret < 0)
34		ksft_exit_fail_msg("%s: failed to create file in tmpdir\n",
35				__func__);
36	close(ret);
37
38	ret = symlinkat("regfile", dfd, "symlink");
39	if (ret < 0)
40		ksft_exit_fail_msg("%s: failed to create symlink in tmpdir\n",
41				__func__);
42
43	return dfd;
44}
45
46int expect_mode(int dfd, const char *filename, mode_t expect_mode)
47{
48	struct stat st;
49	int ret = fstatat(dfd, filename, &st, AT_SYMLINK_NOFOLLOW);
50
51	if (ret)
52		ksft_exit_fail_msg("%s: %s: fstatat failed\n",
53				__func__, filename);
54
55	return (st.st_mode == expect_mode);
56}
57
58void test_regfile(void)
59{
60	int dfd, ret;
61
62	dfd = setup_testdir();
63
64	ret = sys_fchmodat2(dfd, "regfile", 0640, 0);
65
66	if (ret < 0)
67		ksft_exit_fail_msg("%s: fchmodat2(noflag) failed\n", __func__);
68
69	if (!expect_mode(dfd, "regfile", 0100640))
70		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2\n",
71				__func__);
72
73	ret = sys_fchmodat2(dfd, "regfile", 0600, AT_SYMLINK_NOFOLLOW);
74
75	if (ret < 0)
76		ksft_exit_fail_msg("%s: fchmodat2(AT_SYMLINK_NOFOLLOW) failed\n",
77				__func__);
78
79	if (!expect_mode(dfd, "regfile", 0100600))
80		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2 with nofollow\n",
81				__func__);
82
83	ksft_test_result_pass("fchmodat2(regfile)\n");
84}
85
86void test_symlink(void)
87{
88	int dfd, ret;
89
90	dfd = setup_testdir();
91
92	ret = sys_fchmodat2(dfd, "symlink", 0640, 0);
93
94	if (ret < 0)
95		ksft_exit_fail_msg("%s: fchmodat2(noflag) failed\n", __func__);
96
97	if (!expect_mode(dfd, "regfile", 0100640))
98		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2\n",
99				__func__);
100
101	if (!expect_mode(dfd, "symlink", 0120777))
102		ksft_exit_fail_msg("%s: wrong symlink mode bits after fchmodat2\n",
103				__func__);
104
105	ret = sys_fchmodat2(dfd, "symlink", 0600, AT_SYMLINK_NOFOLLOW);
106
107	/*
108	 * On certain filesystems (xfs or btrfs), chmod operation fails. So we
109	 * first check the symlink target but if the operation fails we mark the
110	 * test as skipped.
111	 *
112	 * https://sourceware.org/legacy-ml/libc-alpha/2020-02/msg00467.html
113	 */
114	if (ret == 0 && !expect_mode(dfd, "symlink", 0120600))
115		ksft_exit_fail_msg("%s: wrong symlink mode bits after fchmodat2 with nofollow\n",
116				__func__);
117
118	if (!expect_mode(dfd, "regfile", 0100640))
119		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2 with nofollow\n",
120				__func__);
121
122	if (ret != 0)
123		ksft_test_result_skip("fchmodat2(symlink)\n");
124	else
125		ksft_test_result_pass("fchmodat2(symlink)\n");
126}
127
128#define NUM_TESTS 2
129
130int main(int argc, char **argv)
131{
132	ksft_print_header();
133	ksft_set_plan(NUM_TESTS);
134
135	test_regfile();
136	test_symlink();
137
138	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
139		ksft_exit_fail();
140	else
141		ksft_exit_pass();
142}
143