--- /dev/null
+// 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();
+}
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