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linux-7.2.3/tools/testing/selftests/filesystems/statmount/.gitignore

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+statmount_test_ns
+/*_test

linux-7.2.3/tools/testing/selftests/filesystems/statmount/Makefile

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+CFLAGS += -Wall -O2 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES)
+LDLIBS += -lcap
+
+TEST_GEN_PROGS := statmount_test statmount_test_ns listmount_test
+
+include ../../lib.mk
+
+$(OUTPUT)/statmount_test_ns: ../utils.c

linux-7.2.3/tools/testing/selftests/filesystems/statmount/listmount_test.c

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright (c) 2024 Christian Brauner <brauner@kernel.org>
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <unistd.h>
+
+#include "statmount.h"
+#include "kselftest_harness.h"
+
+#ifndef LISTMOUNT_REVERSE
+#define LISTMOUNT_REVERSE    (1 << 0) /* List later mounts first */
+#endif
+
+#define LISTMNT_BUFFER 10
+
+/* Check that all mount ids are in increasing order. */
+TEST(listmount_forward)
+{
+	uint64_t list[LISTMNT_BUFFER], last_mnt_id = 0;
+
+	for (;;) {
+		ssize_t nr_mounts;
+
+		nr_mounts = listmount(LSMT_ROOT, 0, last_mnt_id,
+				      list, LISTMNT_BUFFER, 0);
+		ASSERT_GE(nr_mounts, 0);
+		if (nr_mounts == 0)
+			break;
+
+		for (size_t cur = 0; cur < nr_mounts; cur++) {
+			if (cur < nr_mounts - 1)
+				ASSERT_LT(list[cur], list[cur + 1]);
+			last_mnt_id = list[cur];
+		}
+	}
+}
+
+/* Check that all mount ids are in decreasing order. */
+TEST(listmount_backward)
+{
+	uint64_t list[LISTMNT_BUFFER], last_mnt_id = 0;
+
+	for (;;) {
+		ssize_t nr_mounts;
+
+		nr_mounts = listmount(LSMT_ROOT, 0, last_mnt_id,
+				      list, LISTMNT_BUFFER, LISTMOUNT_REVERSE);
+		ASSERT_GE(nr_mounts, 0);
+		if (nr_mounts == 0)
+			break;
+
+		for (size_t cur = 0; cur < nr_mounts; cur++) {
+			if (cur < nr_mounts - 1)
+				ASSERT_GT(list[cur], list[cur + 1]);
+			last_mnt_id = list[cur];
+		}
+	}
+}
+
+TEST_HARNESS_MAIN

linux-7.2.3/tools/testing/selftests/filesystems/statmount/statmount.h

@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __STATMOUNT_H
+#define __STATMOUNT_H
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <linux/mount.h>
+#include <asm/unistd.h>
+
+#define STATMOUNT_BUFSIZE (1 << 15)
+
+#ifndef __NR_statmount
+	#if defined __alpha__
+		#define __NR_statmount 567
+	#elif defined _MIPS_SIM
+		#if _MIPS_SIM == _MIPS_SIM_ABI32	/* o32 */
+			#define __NR_statmount 4457
+		#endif
+		#if _MIPS_SIM == _MIPS_SIM_NABI32	/* n32 */
+			#define __NR_statmount 6457
+		#endif
+		#if _MIPS_SIM == _MIPS_SIM_ABI64	/* n64 */
+			#define __NR_statmount 5457
+		#endif
+	#else
+		#define __NR_statmount 457
+	#endif
+#endif
+
+#ifndef __NR_listmount
+	#if defined __alpha__
+		#define __NR_listmount 568
+	#elif defined _MIPS_SIM
+		#if _MIPS_SIM == _MIPS_SIM_ABI32	/* o32 */
+			#define __NR_listmount 4458
+		#endif
+		#if _MIPS_SIM == _MIPS_SIM_NABI32	/* n32 */
+			#define __NR_listmount 6458
+		#endif
+		#if _MIPS_SIM == _MIPS_SIM_ABI64	/* n64 */
+			#define __NR_listmount 5458
+		#endif
+	#else
+		#define __NR_listmount 458
+	#endif
+#endif
+
+static inline int statmount(uint64_t mnt_id, uint64_t mnt_ns_id, uint32_t fd,
+			    uint64_t mask, struct statmount *buf, size_t bufsize,
+			    unsigned int flags)
+{
+	struct mnt_id_req req = {
+		.size = MNT_ID_REQ_SIZE_VER0,
+		.param = mask,
+	};
+
+	if (flags & STATMOUNT_BY_FD) {
+		req.size = MNT_ID_REQ_SIZE_VER1;
+		req.mnt_fd = fd;
+	} else {
+		req.mnt_id = mnt_id;
+		if (mnt_ns_id) {
+			req.size = MNT_ID_REQ_SIZE_VER1;
+			req.mnt_ns_id = mnt_ns_id;
+		}
+	}
+
+	return syscall(__NR_statmount, &req, buf, bufsize, flags);
+}
+
+static inline ssize_t listmount(uint64_t mnt_id, uint64_t mnt_ns_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,
+	};
+
+	if (mnt_ns_id) {
+		req.size = MNT_ID_REQ_SIZE_VER1;
+		req.mnt_ns_id = mnt_ns_id;
+	}
+
+	return syscall(__NR_listmount, &req, list, num, flags);
+}
+
+static inline struct statmount *statmount_alloc(uint64_t mnt_id, uint64_t mnt_ns_id,
+						 uint64_t mask, unsigned int flags)
+{
+	struct statmount *buf;
+	size_t bufsize = STATMOUNT_BUFSIZE;
+	int ret;
+
+	for (;;) {
+		buf = malloc(bufsize);
+		if (!buf)
+			return NULL;
+
+		ret = statmount(mnt_id, mnt_ns_id, 0, mask, buf, bufsize, flags);
+		if (ret == 0)
+			return buf;
+
+		free(buf);
+		if (errno != EOVERFLOW)
+			return NULL;
+
+		bufsize <<= 1;
+	}
+}
+
+static inline struct statmount *statmount_alloc_by_fd(int fd, uint64_t mask)
+{
+	struct statmount *buf;
+	size_t bufsize = STATMOUNT_BUFSIZE;
+	int ret;
+
+	for (;;) {
+		buf = malloc(bufsize);
+		if (!buf)
+			return NULL;
+
+		ret = statmount(0, 0, fd, mask, buf, bufsize, STATMOUNT_BY_FD);
+		if (ret == 0)
+			return buf;
+
+		free(buf);
+		if (errno != EOVERFLOW)
+			return NULL;
+
+		bufsize <<= 1;
+	}
+}
+
+#endif /* __STATMOUNT_H */

linux-7.2.3/tools/testing/selftests/filesystems/statmount/statmount_test.c

@@ -0,0 +1,894 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <stddef.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/stat.h>
+
+#include "statmount.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", "omfs", "openpromfs", "overlay", "pipefs", "proc",
+	"pstore", "pvfs2", "qnx4", "qnx6", "ramfs", "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 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 FILE *f_mountinfo;
+
+static void cleanup_namespace(void)
+{
+	int ret;
+
+	ret = fchdir(orig_root);
+	if (ret == -1)
+		ksft_perror("fchdir to original root");
+
+	ret = chroot(".");
+	if (ret == -1)
+		ksft_perror("chroot to original root");
+
+	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|CLONE_NEWPID);
+	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);
+
+	f_mountinfo = fopen("/proc/self/mountinfo", "re");
+	if (!f_mountinfo)
+		ksft_exit_fail_msg("failed to open mountinfo: %s\n",
+				   strerror(errno));
+
+	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 void test_listmount_empty_root(void)
+{
+	ssize_t res;
+	const unsigned int size = 32;
+	uint64_t list[size];
+
+	res = listmount(LSMT_ROOT, 0, 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, 0, 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, 0, 0, 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, 0, 0, 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, 0, STATMOUNT_MNT_POINT, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount mount point: %s\n",
+				      strerror(errno));
+		return;
+	}
+
+	if (!(sm->mask & STATMOUNT_MNT_POINT)) {
+		ksft_test_result_fail("missing STATMOUNT_MNT_POINT in mask\n");
+		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, 0, STATMOUNT_MNT_ROOT, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount mount root: %s\n",
+				      strerror(errno));
+		return;
+	}
+	if (!(sm->mask & STATMOUNT_MNT_ROOT)) {
+		ksft_test_result_fail("missing STATMOUNT_MNT_ROOT in mask\n");
+		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, 0, STATMOUNT_FS_TYPE, 0);
+	if (!sm) {
+		ksft_test_result_fail("statmount fs type: %s\n",
+				      strerror(errno));
+		return;
+	}
+	if (!(sm->mask & STATMOUNT_FS_TYPE)) {
+		ksft_test_result_fail("missing STATMOUNT_FS_TYPE in mask\n");
+		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_mnt_opts(void)
+{
+	struct statmount *sm;
+	const char *statmount_opts;
+	char *line = NULL;
+	size_t len = 0;
+
+	sm = statmount_alloc(root_id, 0, STATMOUNT_MNT_BASIC | STATMOUNT_MNT_OPTS,
+			     0);
+	if (!sm) {
+		ksft_test_result_fail("statmount mnt opts: %s\n",
+				      strerror(errno));
+		return;
+	}
+
+	if (!(sm->mask & STATMOUNT_MNT_BASIC)) {
+		ksft_test_result_fail("missing STATMOUNT_MNT_BASIC in mask\n");
+		return;
+	}
+
+	while (getline(&line, &len, f_mountinfo) != -1) {
+		int i;
+		char *p, *p2;
+		unsigned int old_mnt_id;
+
+		old_mnt_id = atoi(line);
+		if (old_mnt_id != sm->mnt_id_old)
+			continue;
+
+		for (p = line, i = 0; p && i < 5; i++)
+			p = strchr(p + 1, ' ');
+		if (!p)
+			continue;
+
+		p2 = strchr(p + 1, ' ');
+		if (!p2)
+			continue;
+		*p2 = '\0';
+		p = strchr(p2 + 1, '-');
+		if (!p)
+			continue;
+		for (p++, i = 0; p && i < 2; i++)
+			p = strchr(p + 1, ' ');
+		if (!p)
+			continue;
+		p++;
+
+		/* skip generic superblock options */
+		if (strncmp(p, "ro", 2) == 0)
+			p += 2;
+		else if (strncmp(p, "rw", 2) == 0)
+			p += 2;
+		if (*p == ',')
+			p++;
+		if (strncmp(p, "sync", 4) == 0)
+			p += 4;
+		if (*p == ',')
+			p++;
+		if (strncmp(p, "dirsync", 7) == 0)
+			p += 7;
+		if (*p == ',')
+			p++;
+		if (strncmp(p, "lazytime", 8) == 0)
+			p += 8;
+		if (*p == ',')
+			p++;
+		p2 = strrchr(p, '\n');
+		if (p2)
+			*p2 = '\0';
+
+		if (sm->mask & STATMOUNT_MNT_OPTS)
+			statmount_opts = sm->str + sm->mnt_opts;
+		else
+			statmount_opts = "";
+		if (strcmp(statmount_opts, p) != 0)
+			ksft_test_result_fail(
+				"unexpected mount options: '%s' != '%s'\n",
+				statmount_opts, p);
+		else
+			ksft_test_result_pass("statmount mount options\n");
+		free(sm);
+		free(line);
+		return;
+	}
+
+	ksft_test_result_fail("didnt't find mount entry\n");
+	free(sm);
+	free(line);
+}
+
+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, 0, 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, 0, 0, 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, 0, 0, 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, 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, 0, 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");
+}
+
+static void test_statmount_by_fd(void)
+{
+	struct statmount *sm = NULL;
+	char tmpdir[] = "/statmount.fd.XXXXXX";
+	const char root[] = "/test";
+	char subdir[PATH_MAX], tmproot[PATH_MAX];
+	int fd;
+
+	if (!mkdtemp(tmpdir)) {
+		ksft_perror("mkdtemp");
+		return;
+	}
+
+	if (mount("statmount.test", tmpdir, "tmpfs", 0, NULL)) {
+		ksft_perror("mount");
+		rmdir(tmpdir);
+		return;
+	}
+
+	snprintf(subdir, PATH_MAX, "%s%s", tmpdir, root);
+	snprintf(tmproot, PATH_MAX, "%s/%s", tmpdir, "chroot");
+
+	if (mkdir(subdir, 0755)) {
+		ksft_perror("mkdir");
+		goto err_tmpdir;
+	}
+
+	if (mount(subdir, subdir, NULL, MS_BIND, 0)) {
+		ksft_perror("mount");
+		goto err_subdir;
+	}
+
+	if (mkdir(tmproot, 0755)) {
+		ksft_perror("mkdir");
+		goto err_subdir;
+	}
+
+	fd = open(subdir, O_PATH);
+	if (fd < 0) {
+		ksft_perror("open");
+		goto err_tmproot;
+	}
+
+	if (chroot(tmproot)) {
+		ksft_perror("chroot");
+		goto err_fd;
+	}
+
+	sm = statmount_alloc_by_fd(fd, STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT);
+	if (!sm) {
+		ksft_test_result_fail("statmount by fd failed: %s\n", strerror(errno));
+		goto err_chroot;
+	}
+
+	if (sm->size < sizeof(*sm)) {
+		ksft_test_result_fail("unexpected size: %u < %u\n",
+				      sm->size, (uint32_t) sizeof(*sm));
+		goto err_chroot;
+	}
+
+	if (sm->mask & STATMOUNT_MNT_POINT) {
+		ksft_test_result_fail("STATMOUNT_MNT_POINT unexpectedly set in statmount\n");
+		goto err_chroot;
+	}
+
+	if (!(sm->mask & STATMOUNT_MNT_ROOT)) {
+		ksft_test_result_fail("STATMOUNT_MNT_ROOT not set in statmount\n");
+		goto err_chroot;
+	}
+
+	if (strcmp(root, sm->str + sm->mnt_root) != 0) {
+		ksft_test_result_fail("statmount returned incorrect mnt_root,"
+			"statmount mnt_root: %s != %s\n",
+			sm->str + sm->mnt_root, root);
+		goto err_chroot;
+	}
+
+	if (chroot(".")) {
+		ksft_perror("chroot");
+		goto out;
+	}
+
+	free(sm);
+	sm = statmount_alloc_by_fd(fd, STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT);
+	if (!sm) {
+		ksft_test_result_fail("statmount by fd failed: %s\n", strerror(errno));
+		goto err_fd;
+	}
+
+	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 & STATMOUNT_MNT_POINT)) {
+		ksft_test_result_fail("STATMOUNT_MNT_POINT not set in statmount\n");
+		goto out;
+	}
+
+	if (!(sm->mask & STATMOUNT_MNT_ROOT)) {
+		ksft_test_result_fail("STATMOUNT_MNT_ROOT not set in statmount\n");
+		goto out;
+	}
+
+	if (strcmp(subdir, sm->str + sm->mnt_point) != 0) {
+		ksft_test_result_fail("statmount returned incorrect mnt_point,"
+			"statmount mnt_point: %s != %s\n", sm->str + sm->mnt_point, subdir);
+		goto out;
+	}
+
+	if (strcmp(root, sm->str + sm->mnt_root) != 0) {
+		ksft_test_result_fail("statmount returned incorrect mnt_root,"
+			"statmount mnt_root: %s != %s\n", sm->str + sm->mnt_root, root);
+		goto out;
+	}
+
+	ksft_test_result_pass("statmount by fd\n");
+	goto out;
+err_chroot:
+	chroot(".");
+out:
+	free(sm);
+err_fd:
+	close(fd);
+err_tmproot:
+	rmdir(tmproot);
+err_subdir:
+	umount2(subdir, MNT_DETACH);
+	rmdir(subdir);
+err_tmpdir:
+	umount2(tmpdir, MNT_DETACH);
+	rmdir(tmpdir);
+}
+
+static void test_statmount_by_fd_unmounted(void)
+{
+	const char root[] = "/test.unmounted";
+	char tmpdir[] = "/statmount.fd.XXXXXX";
+	char subdir[PATH_MAX];
+	int fd;
+	struct statmount *sm = NULL;
+
+	if (!mkdtemp(tmpdir)) {
+		ksft_perror("mkdtemp");
+		return;
+	}
+
+	if (mount("statmount.test", tmpdir, "tmpfs", 0, NULL)) {
+		ksft_perror("mount");
+		rmdir(tmpdir);
+		return;
+	}
+
+	snprintf(subdir, PATH_MAX, "%s%s", tmpdir, root);
+
+	if (mkdir(subdir, 0755)) {
+		ksft_perror("mkdir");
+		goto err_tmpdir;
+	}
+
+	if (mount(subdir, subdir, 0, MS_BIND, NULL)) {
+		ksft_perror("mount");
+		goto err_subdir;
+	}
+
+	fd = open(subdir, O_PATH);
+	if (fd < 0) {
+		ksft_perror("open");
+		goto err_subdir;
+	}
+
+	if (umount2(tmpdir, MNT_DETACH)) {
+		ksft_perror("umount2");
+		goto err_fd;
+	}
+
+	sm = statmount_alloc_by_fd(fd, STATMOUNT_MNT_POINT | STATMOUNT_MNT_ROOT);
+	if (!sm) {
+		ksft_test_result_fail("statmount by fd unmounted: %s\n",
+				      strerror(errno));
+		goto err_sm;
+	}
+
+	if (sm->size < sizeof(*sm)) {
+		ksft_test_result_fail("unexpected size: %u < %u\n",
+				      sm->size, (uint32_t) sizeof(*sm));
+		goto err_sm;
+	}
+
+	if (sm->mask & STATMOUNT_MNT_POINT) {
+		ksft_test_result_fail("STATMOUNT_MNT_POINT unexpectedly set in mask\n");
+		goto err_sm;
+	}
+
+	if (!(sm->mask & STATMOUNT_MNT_ROOT)) {
+		ksft_test_result_fail("STATMOUNT_MNT_ROOT not set in mask\n");
+		goto err_sm;
+	}
+
+	if (strcmp(sm->str + sm->mnt_root, root) != 0) {
+		ksft_test_result_fail("statmount returned incorrect mnt_root,"
+			"statmount mnt_root: %s != %s\n",
+			sm->str + sm->mnt_root, root);
+		goto err_sm;
+	}
+
+	ksft_test_result_pass("statmount by fd on unmounted mount\n");
+err_sm:
+	free(sm);
+err_fd:
+	close(fd);
+err_subdir:
+	umount2(subdir, MNT_DETACH);
+	rmdir(subdir);
+err_tmpdir:
+	umount2(tmpdir, MNT_DETACH);
+	rmdir(tmpdir);
+}
+
+#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 | STATMOUNT_MNT_NS_ID;
+
+	ksft_print_header();
+
+	ret = statmount(0, 0, 0, 0, NULL, 0, 0);
+	assert(ret == -1);
+	if (errno == ENOSYS)
+		ksft_exit_skip("statmount() syscall not supported\n");
+
+	setup_namespace();
+
+	ksft_set_plan(17);
+	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_mnt_opts();
+	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();
+	test_statmount_by_fd_unmounted();
+	test_statmount_by_fd();
+
+
+	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+		ksft_exit_fail();
+	else
+		ksft_exit_pass();
+}

linux-7.2.3/tools/testing/selftests/filesystems/statmount/statmount_test_ns.c

@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <sched.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <linux/nsfs.h>
+#include <linux/stat.h>
+
+#include "statmount.h"
+#include "../utils.h"
+#include "kselftest.h"
+
+#define NSID_PASS 0
+#define NSID_FAIL 1
+#define NSID_SKIP 2
+#define NSID_ERROR 3
+
+static void handle_result(int ret, const char *testname)
+{
+	if (ret == NSID_PASS)
+		ksft_test_result_pass("%s\n", testname);
+	else if (ret == NSID_FAIL)
+		ksft_test_result_fail("%s\n", testname);
+	else if (ret == NSID_ERROR)
+		ksft_exit_fail_msg("%s\n", testname);
+	else
+		ksft_test_result_skip("%s\n", testname);
+}
+
+static int get_mnt_ns_id(const char *mnt_ns, uint64_t *mnt_ns_id)
+{
+	int fd = open(mnt_ns, O_RDONLY);
+
+	if (fd < 0) {
+		ksft_print_msg("failed to open for ns %s: %s\n",
+			       mnt_ns, strerror(errno));
+		sleep(60);
+		return NSID_ERROR;
+	}
+
+	if (ioctl(fd, NS_GET_MNTNS_ID, mnt_ns_id) < 0) {
+		ksft_print_msg("failed to get the nsid for ns %s: %s\n",
+			       mnt_ns, strerror(errno));
+		return NSID_ERROR;
+	}
+	close(fd);
+	return NSID_PASS;
+}
+
+static int setup_namespace(void)
+{
+	if (setup_userns() != 0)
+		return NSID_ERROR;
+
+	return NSID_PASS;
+}
+
+static int _test_statmount_mnt_ns_id(void)
+{
+	struct statmount sm;
+	uint64_t mnt_ns_id;
+	uint64_t root_id;
+	int ret;
+
+	ret = get_mnt_ns_id("/proc/self/ns/mnt", &mnt_ns_id);
+	if (ret != NSID_PASS)
+		return ret;
+
+	root_id = get_unique_mnt_id("/");
+	if (!root_id)
+		return NSID_ERROR;
+
+	ret = statmount(root_id, 0, 0, STATMOUNT_MNT_NS_ID, &sm, sizeof(sm), 0);
+	if (ret == -1) {
+		ksft_print_msg("statmount mnt ns id: %s\n", strerror(errno));
+		return NSID_ERROR;
+	}
+
+	if (sm.size != sizeof(sm)) {
+		ksft_print_msg("unexpected size: %u != %u\n", sm.size,
+			       (uint32_t)sizeof(sm));
+		return NSID_FAIL;
+	}
+	if (sm.mask != STATMOUNT_MNT_NS_ID) {
+		ksft_print_msg("statmount mnt ns id unavailable\n");
+		return NSID_SKIP;
+	}
+
+	if (sm.mnt_ns_id != mnt_ns_id) {
+		ksft_print_msg("unexpected mnt ns ID: 0x%llx != 0x%llx\n",
+			       (unsigned long long)sm.mnt_ns_id,
+			       (unsigned long long)mnt_ns_id);
+		return NSID_FAIL;
+	}
+
+	return NSID_PASS;
+}
+
+static int _test_statmount_mnt_ns_id_by_fd(void)
+{
+	struct statmount sm;
+	uint64_t mnt_ns_id;
+	int ret, fd, mounted = 1, status = NSID_ERROR;
+	char mnt[] = "/statmount.fd.XXXXXX";
+
+	ret = get_mnt_ns_id("/proc/self/ns/mnt", &mnt_ns_id);
+	if (ret != NSID_PASS)
+		return ret;
+
+	if (!mkdtemp(mnt)) {
+		ksft_print_msg("statmount by fd mnt ns id mkdtemp: %s\n", strerror(errno));
+		return NSID_ERROR;
+	}
+
+	if (mount(mnt, mnt, NULL, MS_BIND, 0)) {
+		ksft_print_msg("statmount by fd mnt ns id mount: %s\n", strerror(errno));
+		status = NSID_ERROR;
+		goto err;
+	}
+
+	fd = open(mnt, O_PATH);
+	if (fd < 0) {
+		ksft_print_msg("statmount by fd mnt ns id open: %s\n", strerror(errno));
+		goto err;
+	}
+
+	ret = statmount(0, 0, fd, STATMOUNT_MNT_NS_ID, &sm, sizeof(sm), STATMOUNT_BY_FD);
+	if (ret == -1) {
+		ksft_print_msg("statmount mnt ns id statmount: %s\n", strerror(errno));
+		status = NSID_ERROR;
+		goto out;
+	}
+
+	if (sm.size != sizeof(sm)) {
+		ksft_print_msg("unexpected size: %u != %u\n", sm.size,
+			       (uint32_t)sizeof(sm));
+		status = NSID_FAIL;
+		goto out;
+	}
+	if (sm.mask != STATMOUNT_MNT_NS_ID) {
+		ksft_print_msg("statmount mnt ns id unavailable\n");
+		status = NSID_SKIP;
+		goto out;
+	}
+
+	if (sm.mnt_ns_id != mnt_ns_id) {
+		ksft_print_msg("unexpected mnt ns ID: 0x%llx != 0x%llx\n",
+			       (unsigned long long)sm.mnt_ns_id,
+			       (unsigned long long)mnt_ns_id);
+		status = NSID_FAIL;
+		goto out;
+	}
+
+	mounted = 0;
+	if (umount2(mnt, MNT_DETACH)) {
+		ksft_print_msg("statmount by fd mnt ns id umount2: %s\n", strerror(errno));
+		goto out;
+	}
+
+	ret = statmount(0, 0, fd, STATMOUNT_MNT_NS_ID, &sm, sizeof(sm), STATMOUNT_BY_FD);
+	if (ret == -1) {
+		ksft_print_msg("statmount mnt ns id statmount: %s\n", strerror(errno));
+		status = NSID_ERROR;
+		goto out;
+	}
+
+	if (sm.size != sizeof(sm)) {
+		ksft_print_msg("unexpected size: %u != %u\n", sm.size,
+			       (uint32_t)sizeof(sm));
+		status = NSID_FAIL;
+		goto out;
+	}
+
+	if (sm.mask == STATMOUNT_MNT_NS_ID) {
+		ksft_print_msg("unexpected STATMOUNT_MNT_NS_ID in mask\n");
+		status = NSID_FAIL;
+		goto out;
+	}
+
+	status = NSID_PASS;
+out:
+	close(fd);
+	if (mounted)
+		umount2(mnt, MNT_DETACH);
+err:
+	rmdir(mnt);
+	return status;
+}
+
+
+static void test_statmount_mnt_ns_id(void)
+{
+	pid_t pid;
+	int ret;
+
+	pid = fork();
+	if (pid < 0)
+		ksft_exit_fail_msg("failed to fork: %s\n", strerror(errno));
+
+	/* We're the original pid, wait for the result. */
+	if (pid != 0) {
+		ret = wait_for_pid(pid);
+		handle_result(ret, "test statmount ns id");
+		return;
+	}
+
+	ret = setup_namespace();
+	if (ret != NSID_PASS)
+		exit(ret);
+	ret = _test_statmount_mnt_ns_id();
+	if (ret != NSID_PASS)
+		exit(ret);
+	ret = _test_statmount_mnt_ns_id_by_fd();
+	exit(ret);
+}
+
+static int validate_external_listmount(pid_t pid, uint64_t child_nr_mounts)
+{
+	uint64_t list[256];
+	uint64_t mnt_ns_id;
+	uint64_t nr_mounts;
+	char buf[256];
+	int ret;
+
+	/* Get the mount ns id for our child. */
+	snprintf(buf, sizeof(buf), "/proc/%lu/ns/mnt", (unsigned long)pid);
+	ret = get_mnt_ns_id(buf, &mnt_ns_id);
+
+	nr_mounts = listmount(LSMT_ROOT, mnt_ns_id, 0, list, 256, 0);
+	if (nr_mounts == (uint64_t)-1) {
+		ksft_print_msg("listmount: %s\n", strerror(errno));
+		return NSID_ERROR;
+	}
+
+	if (nr_mounts != child_nr_mounts) {
+		ksft_print_msg("listmount results is %zi != %zi\n", nr_mounts,
+			       child_nr_mounts);
+		return NSID_FAIL;
+	}
+
+	/* Validate that all of our entries match our mnt_ns_id. */
+	for (int i = 0; i < nr_mounts; i++) {
+		struct statmount sm;
+
+		ret = statmount(list[i], mnt_ns_id, 0, STATMOUNT_MNT_NS_ID, &sm,
+				sizeof(sm), 0);
+		if (ret < 0) {
+			ksft_print_msg("statmount mnt ns id: %s\n", strerror(errno));
+			return NSID_ERROR;
+		}
+
+		if (sm.mask != STATMOUNT_MNT_NS_ID) {
+			ksft_print_msg("statmount mnt ns id unavailable\n");
+			return NSID_SKIP;
+		}
+
+		if (sm.mnt_ns_id != mnt_ns_id) {
+			ksft_print_msg("listmount gave us the wrong ns id: 0x%llx != 0x%llx\n",
+				       (unsigned long long)sm.mnt_ns_id,
+				       (unsigned long long)mnt_ns_id);
+			return NSID_FAIL;
+		}
+	}
+
+	return NSID_PASS;
+}
+
+static void test_listmount_ns(void)
+{
+	uint64_t nr_mounts;
+	char pval;
+	int child_ready_pipe[2];
+	int parent_ready_pipe[2];
+	pid_t pid;
+	int ret, child_ret;
+
+	if (pipe(child_ready_pipe) < 0)
+		ksft_exit_fail_msg("failed to create the child pipe: %s\n",
+				   strerror(errno));
+	if (pipe(parent_ready_pipe) < 0)
+		ksft_exit_fail_msg("failed to create the parent pipe: %s\n",
+				   strerror(errno));
+
+	pid = fork();
+	if (pid < 0)
+		ksft_exit_fail_msg("failed to fork: %s\n", strerror(errno));
+
+	if (pid == 0) {
+		char cval;
+		uint64_t list[256];
+
+		close(child_ready_pipe[0]);
+		close(parent_ready_pipe[1]);
+
+		ret = setup_namespace();
+		if (ret != NSID_PASS)
+			exit(ret);
+
+		nr_mounts = listmount(LSMT_ROOT, 0, 0, list, 256, 0);
+		if (nr_mounts == (uint64_t)-1) {
+			ksft_print_msg("listmount: %s\n", strerror(errno));
+			exit(NSID_FAIL);
+		}
+
+		/*
+		 * Tell our parent how many mounts we have, and then wait for it
+		 * to tell us we're done.
+		 */
+		if (write(child_ready_pipe[1], &nr_mounts, sizeof(nr_mounts)) !=
+					sizeof(nr_mounts))
+			ret = NSID_ERROR;
+		if (read(parent_ready_pipe[0], &cval, sizeof(cval)) != sizeof(cval))
+			ret = NSID_ERROR;
+		exit(NSID_PASS);
+	}
+
+	close(child_ready_pipe[1]);
+	close(parent_ready_pipe[0]);
+
+	/* Wait until the child has created everything. */
+	if (read(child_ready_pipe[0], &nr_mounts, sizeof(nr_mounts)) !=
+	    sizeof(nr_mounts))
+		ret = NSID_ERROR;
+
+	ret = validate_external_listmount(pid, nr_mounts);
+
+	if (write(parent_ready_pipe[1], &pval, sizeof(pval)) != sizeof(pval))
+		ret = NSID_ERROR;
+
+	child_ret = wait_for_pid(pid);
+	if (child_ret != NSID_PASS)
+		ret = child_ret;
+	handle_result(ret, "test listmount ns id");
+}
+
+int main(void)
+{
+	int ret;
+
+	ksft_print_header();
+	ret = statmount(0, 0, 0, 0, NULL, 0, 0);
+	assert(ret == -1);
+	if (errno == ENOSYS)
+		ksft_exit_skip("statmount() syscall not supported\n");
+
+	ksft_set_plan(2);
+	test_statmount_mnt_ns_id();
+	test_listmount_ns();
+
+	if (ksft_get_fail_cnt() + ksft_get_error_cnt() > 0)
+		ksft_exit_fail();
+	else
+		ksft_exit_pass();
+}