add selftest for statmount/listmount

Initial selftest for the new statmount() and listmount() syscalls.

Signed-off-by: Miklos Szeredi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Christian Brauner <[e-mail]>

tools/testing/selftests/Makefile

···
 TARGETS += filesystems/binderfs
 TARGETS += filesystems/epoll
 TARGETS += filesystems/fat
+TARGETS += filesystems/statmount
 TARGETS += firmware
 TARGETS += fpu
 TARGETS += ftrace

tools/testing/selftests/filesystems/statmount/.gitignore

···
+# SPDX-License-Identifier: GPL-2.0-only
+/*_test

tools/testing/selftests/filesystems/statmount/Makefile

···
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES)
+TEST_GEN_PROGS := statmount_test
+
+include ../../lib.mk

tools/testing/selftests/filesystems/statmount/statmount_test.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <stdint.h>
+#include <sched.h>
+#include <fcntl.h>
+#include <sys/param.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <linux/mount.h>
+#include <linux/stat.h>
+#include <asm/unistd.h>
+
+#include "../../kselftest.h"
+
+static const char *const known_fs[] = {
+	"9p", "adfs", "affs", "afs", "aio", "anon_inodefs", "apparmorfs",
+	"autofs", "bcachefs", "bdev", "befs", "bfs", "binder", "binfmt_misc",
+	"bpf", "btrfs", "btrfs_test_fs", "ceph", "cgroup", "cgroup2", "cifs",
+	"coda", "configfs", "cpuset", "cramfs", "cxl", "dax", "debugfs",
+	"devpts", "devtmpfs", "dmabuf", "drm", "ecryptfs", "efivarfs", "efs",
+	"erofs", "exfat", "ext2", "ext3", "ext4", "f2fs", "functionfs",
+	"fuse", "fuseblk", "fusectl", "gadgetfs", "gfs2", "gfs2meta", "hfs",
+	"hfsplus", "hostfs", "hpfs", "hugetlbfs", "ibmasmfs", "iomem",
+	"ipathfs", "iso9660", "jffs2", "jfs", "minix", "mqueue", "msdos",
+	"nfs", "nfs4", "nfsd", "nilfs2", "nsfs", "ntfs", "ntfs3", "ocfs2",
+	"ocfs2_dlmfs", "ocxlflash", "omfs", "openpromfs", "overlay", "pipefs",
+	"proc", "pstore", "pvfs2", "qnx4", "qnx6", "ramfs", "reiserfs",
+	"resctrl", "romfs", "rootfs", "rpc_pipefs", "s390_hypfs", "secretmem",
+	"securityfs", "selinuxfs", "smackfs", "smb3", "sockfs", "spufs",
+	"squashfs", "sysfs", "sysv", "tmpfs", "tracefs", "ubifs", "udf",
+	"ufs", "v7", "vboxsf", "vfat", "virtiofs", "vxfs", "xenfs", "xfs",
+	"zonefs", NULL };
+
+static int statmount(uint64_t mnt_id, uint64_t mask, struct statmount *buf,
+		     size_t bufsize, unsigned int flags)
+{
+	struct mnt_id_req req = {
+		.size = MNT_ID_REQ_SIZE_VER0,
+		.mnt_id = mnt_id,
+		.param = mask,
+	};
+
+	return syscall(__NR_statmount, &req, buf, bufsize, flags);
+}
+
+static struct statmount *statmount_alloc(uint64_t mnt_id, uint64_t mask, unsigned int flags)
+{
+	size_t bufsize = 1 << 15;
+	struct statmount *buf = NULL, *tmp = alloca(bufsize);
+	int tofree = 0;
+	int ret;
+
+	for (;;) {
+		ret = statmount(mnt_id, mask, tmp, bufsize, flags);
+		if (ret != -1)
+			break;
+		if (tofree)
+			free(tmp);
+		if (errno != EOVERFLOW)
+			return NULL;
+		bufsize <<= 1;
+		tofree = 1;
+		tmp = malloc(bufsize);
+		if (!tmp)
+			return NULL;
+	}
+	buf = malloc(tmp->size);
+	if (buf)
+		memcpy(buf, tmp, tmp->size);
+	if (tofree)
+		free(tmp);
+
+	return buf;
+}
+
+static void write_file(const char *path, const char *val)
+{
+	int fd = open(path, O_WRONLY);
+	size_t len = strlen(val);
+	int ret;
+
+	if (fd == -1)
+		ksft_exit_fail_msg("opening %s for write: %s\n", path, strerror(errno));
+
+	ret = write(fd, val, len);
+	if (ret == -1)
+		ksft_exit_fail_msg("writing to %s: %s\n", path, strerror(errno));
+	if (ret != len)
+		ksft_exit_fail_msg("short write to %s\n", path);
+
+	ret = close(fd);
+	if (ret == -1)
+		ksft_exit_fail_msg("closing %s\n", path);
+}
+
+static uint64_t get_mnt_id(const char *name, const char *path, uint64_t mask)
+{
+	struct statx sx;
+	int ret;
+
+	ret = statx(AT_FDCWD, path, 0, mask, &sx);
+	if (ret == -1)
+		ksft_exit_fail_msg("retrieving %s mount ID for %s: %s\n",
+				   mask & STATX_MNT_ID_UNIQUE ? "unique" : "old",
+				   name, strerror(errno));
+	if (!(sx.stx_mask & mask))
+		ksft_exit_fail_msg("no %s mount ID available for %s\n",
+				   mask & STATX_MNT_ID_UNIQUE ? "unique" : "old",
+				   name);
+
+	return sx.stx_mnt_id;
+}
+
+
+static char root_mntpoint[] = "/tmp/statmount_test_root.XXXXXX";
+static int orig_root;
+static uint64_t root_id, parent_id;
+static uint32_t old_root_id, old_parent_id;
+
+
+static void cleanup_namespace(void)
+{
+	fchdir(orig_root);
+	chroot(".");
+	umount2(root_mntpoint, MNT_DETACH);
+	rmdir(root_mntpoint);
+}
+
+static void setup_namespace(void)
+{
+	int ret;
+	char buf[32];
+	uid_t uid = getuid();
+	gid_t gid = getgid();
+
+	ret = unshare(CLONE_NEWNS|CLONE_NEWUSER);
+	if (ret == -1)
+		ksft_exit_fail_msg("unsharing mountns and userns: %s\n",
+				   strerror(errno));
+
+	sprintf(buf, "0 %d 1", uid);
+	write_file("/proc/self/uid_map", buf);
+	write_file("/proc/self/setgroups", "deny");
+	sprintf(buf, "0 %d 1", gid);
+	write_file("/proc/self/gid_map", buf);
+
+	ret = mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL);
+	if (ret == -1)
+		ksft_exit_fail_msg("making mount tree private: %s\n",
+				   strerror(errno));
+
+	if (!mkdtemp(root_mntpoint))
+		ksft_exit_fail_msg("creating temporary directory %s: %s\n",
+				   root_mntpoint, strerror(errno));
+
+	old_parent_id = get_mnt_id("parent", root_mntpoint, STATX_MNT_ID);
+	parent_id = get_mnt_id("parent", root_mntpoint, STATX_MNT_ID_UNIQUE);
+
+	orig_root = open("/", O_PATH);
+	if (orig_root == -1)
+		ksft_exit_fail_msg("opening root directory: %s",
+				   strerror(errno));
+
+	atexit(cleanup_namespace);
+
+	ret = mount(root_mntpoint, root_mntpoint, NULL, MS_BIND, NULL);
+	if (ret == -1)
+		ksft_exit_fail_msg("mounting temp root %s: %s\n",
+				   root_mntpoint, strerror(errno));
+
+	ret = chroot(root_mntpoint);
+	if (ret == -1)
+		ksft_exit_fail_msg("chroot to temp root %s: %s\n",
+				   root_mntpoint, strerror(errno));
+
+	ret = chdir("/");
+	if (ret == -1)
+		ksft_exit_fail_msg("chdir to root: %s\n", strerror(errno));
+
+	old_root_id = get_mnt_id("root", "/", STATX_MNT_ID);
+	root_id = get_mnt_id("root", "/", STATX_MNT_ID_UNIQUE);
+}
+
+static int setup_mount_tree(int log2_num)
+{
+	int ret, i;
+
+	ret = mount("", "/", NULL, MS_REC|MS_SHARED, NULL);
+	if (ret == -1) {
+		ksft_test_result_fail("making mount tree shared: %s\n",
+				   strerror(errno));
+		return -1;
+	}
+
+	for (i = 0; i < log2_num; i++) {
+		ret = mount("/", "/", NULL, MS_BIND, NULL);
+		if (ret == -1) {
+			ksft_test_result_fail("mounting submount %s: %s\n",
+					      root_mntpoint, strerror(errno));
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static ssize_t listmount(uint64_t mnt_id, uint64_t last_mnt_id,
+			 uint64_t list[], size_t num, unsigned int flags)
+{
+	struct mnt_id_req req = {
+		.size = MNT_ID_REQ_SIZE_VER0,
+		.mnt_id = mnt_id,
+		.param = last_mnt_id,
+	};
+
+	return syscall(__NR_listmount, &req, list, num, flags);
+}
+
+static void test_listmount_empty_root(void)
+{
+	ssize_t res;
+	const unsigned int size = 32;
+	uint64_t list[size];
+
+	res = listmount(LSMT_ROOT, 0, list, size, 0);
+	if (res == -1) {
+		ksft_test_result_fail("listmount: %s\n", strerror(errno));
+		return;
+	}
+	if (res != 1) {
+		ksft_test_result_fail("listmount result is %zi != 1\n", res);
+		return;
+	}
+
+	if (list[0] != root_id) {
+		ksft_test_result_fail("listmount ID doesn't match 0x%llx != 0x%llx\n",
+				      (unsigned long long) list[0],
+				      (unsigned long long) root_id);
+		return;
+	}
+
+	ksft_test_result_pass("listmount empty root\n");
+}
+
+static void test_statmount_zero_mask(void)
+{
+	struct statmount sm;
+	int ret;
+
+	ret = statmount(root_id, 0, &sm, sizeof(sm), 0);
+	if (ret == -1) {
+		ksft_test_result_fail("statmount zero mask: %s\n",
+				      strerror(errno));
+		return;
+	}
+	if (sm.size != sizeof(sm)) {
+		ksft_test_result_fail("unexpected size: %u != %u\n",
+				      sm.size, (uint32_t) sizeof(sm));
+		return;
+	}
+	if (sm.mask != 0) {
+		ksft_test_result_fail("unexpected mask: 0x%llx != 0x0\n",
+				      (unsigned long long) sm.mask);
+		return;
+	}
+
+	ksft_test_result_pass("statmount zero mask\n");
+}
+
+static void test_statmount_mnt_basic(void)
+{
+	struct statmount sm;
+	int ret;
+	uint64_t mask = STATMOUNT_MNT_BASIC;
+
+	ret = statmount(root_id, mask, &sm, sizeof(sm), 0);
+	if (ret == -1) {
+		ksft_test_result_fail("statmount mnt basic: %s\n",
+				      strerror(errno));
+		return;
+	}
+	if (sm.size != sizeof(sm)) {
+		ksft_test_result_fail("unexpected size: %u != %u\n",
+				      sm.size, (uint32_t) sizeof(sm));
+		return;
+	}
+	if (sm.mask != mask) {
+		ksft_test_result_skip("statmount mnt basic unavailable\n");
+		return;
+	}
+
+	if (sm.mnt_id != root_id) {
+		ksft_test_result_fail("unexpected root ID: 0x%llx != 0x%llx\n",
+				      (unsigned long long) sm.mnt_id,
+				      (unsigned long long) root_id);
+		return;
+	}
+
+	if (sm.mnt_id_old != old_root_id) {
+		ksft_test_result_fail("unexpected old root ID: %u != %u\n",
+				      sm.mnt_id_old, old_root_id);
+		return;
+	}
+
+	if (sm.mnt_parent_id != parent_id) {
+		ksft_test_result_fail("unexpected parent ID: 0x%llx != 0x%llx\n",
+				      (unsigned long long) sm.mnt_parent_id,
+				      (unsigned long long) parent_id);
+		return;
+	}
+
+	if (sm.mnt_parent_id_old != old_parent_id) {
+		ksft_test_result_fail("unexpected old parent ID: %u != %u\n",
+				      sm.mnt_parent_id_old, old_parent_id);
+		return;
+	}
+
+	if (sm.mnt_propagation != MS_PRIVATE) {
+		ksft_test_result_fail("unexpected propagation: 0x%llx\n",
+				      (unsigned long long) sm.mnt_propagation);
+		return;
+	}
+
+	ksft_test_result_pass("statmount mnt basic\n");
+}
+
+
+static void test_statmount_sb_basic(void)
+{
+	struct statmount sm;
+	int ret;
+	uint64_t mask = STATMOUNT_SB_BASIC;
+	struct statx sx;
+	struct statfs sf;
+
+	ret = statmount(root_id, mask, &sm, sizeof(sm), 0);
+	if (ret == -1) {
+		ksft_test_result_fail("statmount sb basic: %s\n",
+				      strerror(errno));
+		return;
+	}
+	if (sm.size != sizeof(sm)) {
+		ksft_test_result_fail("unexpected size: %u != %u\n",
+				      sm.size, (uint32_t) sizeof(sm));
+		return;
+	}
+	if (sm.mask != mask) {
+		ksft_test_result_skip("statmount sb basic unavailable\n");
+		return;
+	}
+
+	ret = statx(AT_FDCWD, "/", 0, 0, &sx);
+	if (ret == -1) {
+		ksft_test_result_fail("stat root failed: %s\n",
+				      strerror(errno));
+		return;
+	}
+
+	if (sm.sb_dev_major != sx.stx_dev_major ||
+	    sm.sb_dev_minor != sx.stx_dev_minor) {
+		ksft_test_result_fail("unexpected sb dev %u:%u != %u:%u\n",
+				      sm.sb_dev_major, sm.sb_dev_minor,
+				      sx.stx_dev_major, sx.stx_dev_minor);
+		return;
+	}
+
+	ret = statfs("/", &sf);
+	if (ret == -1) {
+		ksft_test_result_fail("statfs root failed: %s\n",
+				      strerror(errno));
+		return;
+	}
+
+	if (sm.sb_magic != sf.f_type) {
+		ksft_test_result_fail("unexpected sb magic: 0x%llx != 0x%lx\n",
+				      (unsigned long long) sm.sb_magic,
+				      sf.f_type);
+		return;
+	}
+
+	ksft_test_result_pass("statmount sb basic\n");
+}
+
+static void test_statmount_mnt_point(void)
+{
+	struct statmount *sm;
+
+	sm = statmount_alloc(root_id, STATMOUNT_MNT_POINT, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount mount point: %s\n",
+				      strerror(errno));
+		return;
+	}
+
+	if (strcmp(sm->str + sm->mnt_point, "/") != 0) {
+		ksft_test_result_fail("unexpected mount point: '%s' != '/'\n",
+				      sm->str + sm->mnt_point);
+		goto out;
+	}
+	ksft_test_result_pass("statmount mount point\n");
+out:
+	free(sm);
+}
+
+static void test_statmount_mnt_root(void)
+{
+	struct statmount *sm;
+	const char *mnt_root, *last_dir, *last_root;
+
+	last_dir = strrchr(root_mntpoint, '/');
+	assert(last_dir);
+	last_dir++;
+
+	sm = statmount_alloc(root_id, STATMOUNT_MNT_ROOT, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount mount root: %s\n",
+				      strerror(errno));
+		return;
+	}
+	mnt_root = sm->str + sm->mnt_root;
+	last_root = strrchr(mnt_root, '/');
+	if (last_root)
+		last_root++;
+	else
+		last_root = mnt_root;
+
+	if (strcmp(last_dir, last_root) != 0) {
+		ksft_test_result_fail("unexpected mount root last component: '%s' != '%s'\n",
+				      last_root, last_dir);
+		goto out;
+	}
+	ksft_test_result_pass("statmount mount root\n");
+out:
+	free(sm);
+}
+
+static void test_statmount_fs_type(void)
+{
+	struct statmount *sm;
+	const char *fs_type;
+	const char *const *s;
+
+	sm = statmount_alloc(root_id, STATMOUNT_FS_TYPE, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount fs type: %s\n",
+				      strerror(errno));
+		return;
+	}
+	fs_type = sm->str + sm->fs_type;
+	for (s = known_fs; s != NULL; s++) {
+		if (strcmp(fs_type, *s) == 0)
+			break;
+	}
+	if (!s)
+		ksft_print_msg("unknown filesystem type: %s\n", fs_type);
+
+	ksft_test_result_pass("statmount fs type\n");
+	free(sm);
+}
+
+static void test_statmount_string(uint64_t mask, size_t off, const char *name)
+{
+	struct statmount *sm;
+	size_t len, shortsize, exactsize;
+	uint32_t start, i;
+	int ret;
+
+	sm = statmount_alloc(root_id, mask, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount %s: %s\n", name,
+				      strerror(errno));
+		goto out;
+	}
+	if (sm->size < sizeof(*sm)) {
+		ksft_test_result_fail("unexpected size: %u < %u\n",
+				      sm->size, (uint32_t) sizeof(*sm));
+		goto out;
+	}
+	if (sm->mask != mask) {
+		ksft_test_result_skip("statmount %s unavailable\n", name);
+		goto out;
+	}
+	len = sm->size - sizeof(*sm);
+	start = ((uint32_t *) sm)[off];
+
+	for (i = start;; i++) {
+		if (i >= len) {
+			ksft_test_result_fail("string out of bounds\n");
+			goto out;
+		}
+		if (!sm->str[i])
+			break;
+	}
+	exactsize = sm->size;
+	shortsize = sizeof(*sm) + i;
+
+	ret = statmount(root_id, mask, sm, exactsize, 0);
+	if (ret == -1) {
+		ksft_test_result_fail("statmount exact size: %s\n",
+				      strerror(errno));
+		goto out;
+	}
+	errno = 0;
+	ret = statmount(root_id, mask, sm, shortsize, 0);
+	if (ret != -1 || errno != EOVERFLOW) {
+		ksft_test_result_fail("should have failed with EOVERFLOW: %s\n",
+				      strerror(errno));
+		goto out;
+	}
+
+	ksft_test_result_pass("statmount string %s\n", name);
+out:
+	free(sm);
+}
+
+static void test_listmount_tree(void)
+{
+	ssize_t res;
+	const unsigned int log2_num = 4;
+	const unsigned int step = 3;
+	const unsigned int size = (1 << log2_num) + step + 1;
+	size_t num, expect = 1 << log2_num;
+	uint64_t list[size];
+	uint64_t list2[size];
+	size_t i;
+
+
+	res = setup_mount_tree(log2_num);
+	if (res == -1)
+		return;
+
+	num = res = listmount(LSMT_ROOT, 0, list, size, 0);
+	if (res == -1) {
+		ksft_test_result_fail("listmount: %s\n", strerror(errno));
+		return;
+	}
+	if (num != expect) {
+		ksft_test_result_fail("listmount result is %zi != %zi\n",
+				      res, expect);
+		return;
+	}
+
+	for (i = 0; i < size - step;) {
+		res = listmount(LSMT_ROOT, i ? list2[i - 1] : 0, list2 + i, step, 0);
+		if (res == -1)
+			ksft_test_result_fail("short listmount: %s\n",
+					      strerror(errno));
+		i += res;
+		if (res < step)
+			break;
+	}
+	if (i != num) {
+		ksft_test_result_fail("different number of entries: %zu != %zu\n",
+				      i, num);
+		return;
+	}
+	for (i = 0; i < num; i++) {
+		if (list2[i] != list[i]) {
+			ksft_test_result_fail("different value for entry %zu: 0x%llx != 0x%llx\n",
+					      i,
+					      (unsigned long long) list2[i],
+					      (unsigned long long) list[i]);
+		}
+	}
+
+	ksft_test_result_pass("listmount tree\n");
+}
+
+#define str_off(memb) (offsetof(struct statmount, memb) / sizeof(uint32_t))
+
+int main(void)
+{
+	int ret;
+	uint64_t all_mask = STATMOUNT_SB_BASIC | STATMOUNT_MNT_BASIC |
+		STATMOUNT_PROPAGATE_FROM | STATMOUNT_MNT_ROOT |
+		STATMOUNT_MNT_POINT | STATMOUNT_FS_TYPE;
+
+	ksft_print_header();
+
+	ret = statmount(0, 0, NULL, 0, 0);
+	assert(ret == -1);
+	if (errno == ENOSYS)
+		ksft_exit_skip("statmount() syscall not supported\n");
+
+	setup_namespace();
+
+	ksft_set_plan(14);
+	test_listmount_empty_root();
+	test_statmount_zero_mask();
+	test_statmount_mnt_basic();
+	test_statmount_sb_basic();
+	test_statmount_mnt_root();
+	test_statmount_mnt_point();
+	test_statmount_fs_type();
+	test_statmount_string(STATMOUNT_MNT_ROOT, str_off(mnt_root), "mount root");
+	test_statmount_string(STATMOUNT_MNT_POINT, str_off(mnt_point), "mount point");
+	test_statmount_string(STATMOUNT_FS_TYPE, str_off(fs_type), "fs type");
+	test_statmount_string(all_mask, str_off(mnt_root), "mount root & all");
+	test_statmount_string(all_mask, str_off(mnt_point), "mount point & all");
+	test_statmount_string(all_mask, str_off(fs_type), "fs type & all");
+
+	test_listmount_tree();
+
+
+	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+		ksft_exit_fail();
+	else
+		ksft_exit_pass();
+}