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
sys_fchmodat2(int dfd,const char * filename,mode_t mode,int flags)12 int 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
setup_testdir(void)19 int 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
expect_mode(int dfd,const char * filename,mode_t expect_mode)46 int 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
test_regfile(void)58 void 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
test_symlink(void)86 void 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
main(int argc,char ** argv)130 int 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