[LTP] [PATCH v6 4/5] Add fchmodat2_01 test

[Andrea Cervesato]

From: Andrea Cervesato <andrea.cervesato@suse.com>

This test verifies that fchmodat2() syscall is properly working with
AT_SYMLINK_NOFOLLOW on regular files. When AT_SYMLINK_NOFOLLOW is used
on symbolic links instead, we check for EOPNOTSUPP, since the feature is
not implemented for VFS.

Reviewed-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                                   |   2 +
 testcases/kernel/syscalls/fchmodat2/.gitignore     |   1 +
 testcases/kernel/syscalls/fchmodat2/Makefile       |   7 ++
 testcases/kernel/syscalls/fchmodat2/fchmodat2_01.c | 117 +++++++++++++++++++++
 4 files changed, 127 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index 9b3cba667..50298d01e 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -270,6 +270,8 @@ fchmod06 fchmod06
 fchmodat01 fchmodat01
 fchmodat02 fchmodat02
 
+fchmodat2_01 fchmodat2_01
+
 fchown01 fchown01
 fchown01_16 fchown01_16
 fchown02 fchown02
diff --git a/testcases/kernel/syscalls/fchmodat2/.gitignore b/testcases/kernel/syscalls/fchmodat2/.gitignore
new file mode 100644
index 000000000..47d5e2427
--- /dev/null
+++ b/testcases/kernel/syscalls/fchmodat2/.gitignore
@@ -0,0 +1 @@
+fchmodat2_01
diff --git a/testcases/kernel/syscalls/fchmodat2/Makefile b/testcases/kernel/syscalls/fchmodat2/Makefile
new file mode 100644
index 000000000..8cf1b9024
--- /dev/null
+++ b/testcases/kernel/syscalls/fchmodat2/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+
+top_srcdir		?= ../../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syscalls/fchmodat2/fchmodat2_01.c b/testcases/kernel/syscalls/fchmodat2/fchmodat2_01.c
new file mode 100644
index 000000000..f9f353e76
--- /dev/null
+++ b/testcases/kernel/syscalls/fchmodat2/fchmodat2_01.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * This test verifies that fchmodat2() syscall is properly working with
+ * regular files, symbolic links and directories. AT_SYMLINK_NOFOLLOW is a
+ * special feature that is not enabled in VFS for symbolic links since
+ * (introduced by 5d1f903f75a8), so we only verify that EOPNOTSUPP is correctly
+ * raised when used on those particular files.
+ */
+
+#include "tst_test.h"
+#include "tst_safe_file_at.h"
+#include "lapi/fcntl.h"
+#include "lapi/stat.h"
+
+#define MNTPOINT "mntpoint"
+#define FNAME "myfile"
+#define SNAME "symlink"
+#define DNAME "mydir"
+#define DNAME_PATH MNTPOINT"/"DNAME
+
+static int fd_dir = -1;
+
+static void verify_mode(int dirfd, const char *path, mode_t mode)
+{
+	struct stat st;
+
+	SAFE_FSTATAT(dirfd, path, &st, AT_SYMLINK_NOFOLLOW);
+	TST_EXP_EQ_LI(st.st_mode, mode);
+}
+
+static void test_regular_file(void)
+{
+	tst_res(TINFO, "Using regular files");
+
+	SAFE_CHMOD(MNTPOINT"/"FNAME, 0640);
+
+	SAFE_FCHMODAT2(fd_dir, FNAME, 0700, 0);
+	verify_mode(fd_dir, FNAME, S_IFREG | 0700);
+
+	SAFE_FCHMODAT2(fd_dir, FNAME, 0700, AT_SYMLINK_NOFOLLOW);
+	verify_mode(fd_dir, FNAME, S_IFREG | 0700);
+}
+
+static void test_symbolic_link(void)
+{
+	tst_res(TINFO, "Using symbolic link");
+
+	SAFE_FCHMODAT2(fd_dir, SNAME, 0700, 0);
+	verify_mode(fd_dir, FNAME, S_IFREG | 0700);
+	verify_mode(fd_dir, SNAME, S_IFLNK | 0777);
+
+	TST_EXP_FAIL(tst_syscall(__NR_fchmodat2,
+		fd_dir, SNAME, 0640, AT_SYMLINK_NOFOLLOW),
+		EOPNOTSUPP);
+}
+
+static void test_empty_folder(void)
+{
+	tst_res(TINFO, "Using empty folder");
+
+	int fd;
+
+	SAFE_CHMOD(DNAME_PATH, 0640);
+	fd = SAFE_OPEN(DNAME_PATH, O_PATH | O_DIRECTORY, 0640);
+
+	SAFE_FCHMODAT2(fd, "", 0777, AT_EMPTY_PATH);
+	verify_mode(fd_dir, DNAME, S_IFDIR | 0777);
+
+	SAFE_CLOSE(fd);
+}
+
+static void run(void)
+{
+	test_regular_file();
+	test_empty_folder();
+	test_symbolic_link();
+}
+
+static void setup(void)
+{
+	fd_dir = SAFE_OPEN(MNTPOINT, O_PATH | O_DIRECTORY, 0640);
+
+	if (access(DNAME_PATH, F_OK) == -1)
+		SAFE_MKDIR(DNAME_PATH, 0640);
+
+	SAFE_TOUCH(MNTPOINT"/"FNAME, 0640, NULL);
+	SAFE_SYMLINKAT(FNAME, fd_dir, SNAME);
+}
+
+static void cleanup(void)
+{
+	SAFE_UNLINKAT(fd_dir, SNAME, 0);
+	SAFE_RMDIR(DNAME_PATH);
+
+	if (fd_dir != -1)
+		SAFE_CLOSE(fd_dir);
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.setup = setup,
+	.cleanup = cleanup,
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.format_device = 1,
+	.all_filesystems = 1,
+	.tags = (const struct tst_tag[]) {
+		{"linux-git", "5d1f903f75a8"},
+		{}
+	}
+};

-- 
2.43.0