fchmodat2_test.c

  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}