Unverified Commit 4859c257 authored by Alexey Gladkov's avatar Alexey Gladkov Committed by Christian Brauner
Browse files

selftests: Add fchmodat2 selftest 



The test marks as skipped if a syscall with the AT_SYMLINK_NOFOLLOW flag
fails. This is because not all filesystems support changing the mode
bits of symlinks properly. These filesystems return an error but change
the mode bits:

newfstatat(4, "regfile", {st_mode=S_IFREG|0640, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0
newfstatat(4, "symlink", {st_mode=S_IFLNK|0777, st_size=7, ...}, AT_SYMLINK_NOFOLLOW) = 0
syscall_0x1c3(0x4, 0x55fa1f244396, 0x180, 0x100, 0x55fa1f24438e, 0x34) = -1 EOPNOTSUPP (Operation not supported)
newfstatat(4, "regfile", {st_mode=S_IFREG|0640, st_size=0, ...}, AT_SYMLINK_NOFOLLOW) = 0

This happens with btrfs and xfs:

 $ tools/testing/selftests/fchmodat2/fchmodat2_test
 TAP version 13
 1..1
 ok 1 # SKIP fchmodat2(symlink)
 # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:1 error:0

 $ stat /tmp/ksft-fchmodat2.*/symlink
   File: /tmp/ksft-fchmodat2.3NCqlE/symlink -> regfile
   Size: 7               Blocks: 0          IO Block: 4096   symbolic link
 Device: 7,0     Inode: 133         Links: 1
 Access: (0600/lrw-------)  Uid: (    0/    root)   Gid: (    0/    root)

Signed-off-by: default avatarAlexey Gladkov <legion@kernel.org>
Message-Id: <4532a04a870ff589ba62ceeacf76f0bd81b9ba01.1689092120.git.legion@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 78252deb

tools/testing/selftests/Makefile

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@@ -18,6 +18,7 @@ TARGETS += drivers/net/bonding 
TARGETS += drivers/net/team

TARGETS += efivarfs

TARGETS += exec

TARGETS += fchmodat2

TARGETS += filesystems

TARGETS += filesystems/binderfs

TARGETS += filesystems/epoll

tools/testing/selftests/fchmodat2/.gitignore

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# SPDX-License-Identifier: GPL-2.0-only

/*_test

tools/testing/selftests/fchmodat2/Makefile

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# SPDX-License-Identifier: GPL-2.0-or-later



CFLAGS += -Wall -O2 -g -fsanitize=address -fsanitize=undefined

TEST_GEN_PROGS := fchmodat2_test



include ../lib.mk

tools/testing/selftests/fchmodat2/fchmodat2_test.c

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// SPDX-License-Identifier: GPL-2.0-or-later



#define _GNU_SOURCE

#include <fcntl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <syscall.h>

#include <unistd.h>



#include "../kselftest.h"



#ifndef __NR_fchmodat2

	#if defined __alpha__

		#define __NR_fchmodat2 562

	#elif defined _MIPS_SIM

		#if _MIPS_SIM == _MIPS_SIM_ABI32	/* o32 */

			#define __NR_fchmodat2 (452 + 4000)

		#endif

		#if _MIPS_SIM == _MIPS_SIM_NABI32	/* n32 */

			#define __NR_fchmodat2 (452 + 6000)

		#endif

		#if _MIPS_SIM == _MIPS_SIM_ABI64	/* n64 */

			#define __NR_fchmodat2 (452 + 5000)

		#endif

	#elif defined __ia64__

		#define __NR_fchmodat2 (452 + 1024)

	#else

		#define __NR_fchmodat2 452

	#endif

#endif



int sys_fchmodat2(int dfd, const char *filename, mode_t mode, int flags)

{

	int ret = syscall(__NR_fchmodat2, dfd, filename, mode, flags);



	return ret >= 0 ? ret : -errno;

}



int setup_testdir(void)

{

	int dfd, ret;

	char dirname[] = "/tmp/ksft-fchmodat2.XXXXXX";



	/* Make the top-level directory. */

	if (!mkdtemp(dirname))

		ksft_exit_fail_msg("%s: failed to create tmpdir\n", __func__);



	dfd = open(dirname, O_PATH | O_DIRECTORY);

	if (dfd < 0)

		ksft_exit_fail_msg("%s: failed to open tmpdir\n", __func__);



	ret = openat(dfd, "regfile", O_CREAT | O_WRONLY | O_TRUNC, 0644);

	if (ret < 0)

		ksft_exit_fail_msg("%s: failed to create file in tmpdir\n",

				__func__);

	close(ret);



	ret = symlinkat("regfile", dfd, "symlink");

	if (ret < 0)

		ksft_exit_fail_msg("%s: failed to create symlink in tmpdir\n",

				__func__);



	return dfd;

}



int expect_mode(int dfd, const char *filename, mode_t expect_mode)

{

	struct stat st;

	int ret = fstatat(dfd, filename, &st, AT_SYMLINK_NOFOLLOW);



	if (ret)

		ksft_exit_fail_msg("%s: %s: fstatat failed\n",

				__func__, filename);



	return (st.st_mode == expect_mode);

}



void test_regfile(void)

{

	int dfd, ret;



	dfd = setup_testdir();



	ret = sys_fchmodat2(dfd, "regfile", 0640, 0);



	if (ret < 0)

		ksft_exit_fail_msg("%s: fchmodat2(noflag) failed\n", __func__);



	if (!expect_mode(dfd, "regfile", 0100640))

		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2\n",

				__func__);



	ret = sys_fchmodat2(dfd, "regfile", 0600, AT_SYMLINK_NOFOLLOW);



	if (ret < 0)

		ksft_exit_fail_msg("%s: fchmodat2(AT_SYMLINK_NOFOLLOW) failed\n",

				__func__);



	if (!expect_mode(dfd, "regfile", 0100600))

		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2 with nofollow\n",

				__func__);



	ksft_test_result_pass("fchmodat2(regfile)\n");

}



void test_symlink(void)

{

	int dfd, ret;



	dfd = setup_testdir();



	ret = sys_fchmodat2(dfd, "symlink", 0640, 0);



	if (ret < 0)

		ksft_exit_fail_msg("%s: fchmodat2(noflag) failed\n", __func__);



	if (!expect_mode(dfd, "regfile", 0100640))

		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2\n",

				__func__);



	if (!expect_mode(dfd, "symlink", 0120777))

		ksft_exit_fail_msg("%s: wrong symlink mode bits after fchmodat2\n",

				__func__);



	ret = sys_fchmodat2(dfd, "symlink", 0600, AT_SYMLINK_NOFOLLOW);



	/*

	 * On certain filesystems (xfs or btrfs), chmod operation fails. So we

	 * first check the symlink target but if the operation fails we mark the

	 * test as skipped.

	 *

	 * https://sourceware.org/legacy-ml/libc-alpha/2020-02/msg00467.html

	 */

	if (ret == 0 && !expect_mode(dfd, "symlink", 0120600))

		ksft_exit_fail_msg("%s: wrong symlink mode bits after fchmodat2 with nofollow\n",

				__func__);



	if (!expect_mode(dfd, "regfile", 0100640))

		ksft_exit_fail_msg("%s: wrong file mode bits after fchmodat2 with nofollow\n",

				__func__);



	if (ret != 0)

		ksft_test_result_skip("fchmodat2(symlink)\n");

	else

		ksft_test_result_pass("fchmodat2(symlink)\n");

}



#define NUM_TESTS 2



int main(int argc, char **argv)

{

	ksft_print_header();

	ksft_set_plan(NUM_TESTS);



	test_regfile();

	test_symlink();



	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)

		ksft_exit_fail();

	else

		ksft_exit_pass();

}