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// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (c) 2024 Christian Brauner <brauner@kernel.org>
#define _GNU_SOURCE
#include <errno.h>
#include <limits.h>
#include <linux/types.h>
#include <inttypes.h>
#include <stdio.h>
#include "../../tools/testing/selftests/pidfd/pidfd.h"
#include "samples-vfs.h"
static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask,
struct statmount *stmnt, size_t bufsize,
unsigned int flags)
{
struct mnt_id_req req = {
.size = MNT_ID_REQ_SIZE_VER1,
.mnt_id = mnt_id,
.param = mask,
.mnt_ns_id = mnt_ns_id,
};
return syscall(__NR_statmount, &req, stmnt, bufsize, flags);
}
static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id,
__u64 mask, unsigned int flags)
{
size_t bufsize = 1 << 15;
struct statmount *stmnt = NULL, *tmp = NULL;
int ret;
for (;;) {
tmp = realloc(stmnt, bufsize);
if (!tmp)
goto out;
stmnt = tmp;
ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags);
if (!ret)
return stmnt;
if (errno != EOVERFLOW)
goto out;
bufsize <<= 1;
if (bufsize >= UINT_MAX / 2)
goto out;
}
out:
free(stmnt);
return NULL;
}
static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id,
__u64 list[], size_t num, unsigned int flags)
{
struct mnt_id_req req = {
.size = MNT_ID_REQ_SIZE_VER1,
.mnt_id = mnt_id,
.param = last_mnt_id,
.mnt_ns_id = mnt_ns_id,
};
return syscall(__NR_listmount, &req, list, num, flags);
}
int main(int argc, char *argv[])
{
#define LISTMNT_BUFFER 10
__u64 list[LISTMNT_BUFFER], last_mnt_id = 0;
int ret, pidfd, fd_mntns;
struct mnt_ns_info info = {};
pidfd = sys_pidfd_open(getpid(), 0);
if (pidfd < 0)
die_errno("pidfd_open failed");
fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0);
if (fd_mntns < 0)
die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed");
ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info);
if (ret < 0)
die_errno("ioctl(NS_GET_MNTNS_ID) failed");
printf("Listing %u mounts for mount namespace %" PRIu64 "\n",
info.nr_mounts, (uint64_t)info.mnt_ns_id);
for (;;) {
ssize_t nr_mounts;
next:
nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id,
info.mnt_ns_id, list, LISTMNT_BUFFER,
0);
if (nr_mounts <= 0) {
int fd_mntns_next;
printf("Finished listing %u mounts for mount namespace %" PRIu64 "\n\n",
info.nr_mounts, (uint64_t)info.mnt_ns_id);
fd_mntns_next = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info);
if (fd_mntns_next < 0) {
if (errno == ENOENT) {
printf("Finished listing all mount namespaces\n");
exit(0);
}
die_errno("ioctl(NS_MNT_GET_NEXT) failed");
}
close(fd_mntns);
fd_mntns = fd_mntns_next;
last_mnt_id = 0;
printf("Listing %u mounts for mount namespace %" PRIu64 "\n",
info.nr_mounts, (uint64_t)info.mnt_ns_id);
goto next;
}
for (size_t cur = 0; cur < nr_mounts; cur++) {
struct statmount *stmnt;
last_mnt_id = list[cur];
stmnt = sys_statmount(last_mnt_id, info.mnt_ns_id,
STATMOUNT_SB_BASIC |
STATMOUNT_MNT_BASIC |
STATMOUNT_MNT_ROOT |
STATMOUNT_MNT_POINT |
STATMOUNT_MNT_NS_ID |
STATMOUNT_MNT_OPTS |
STATMOUNT_FS_TYPE, 0);
if (!stmnt) {
printf("Failed to statmount(%" PRIu64 ") in mount namespace(%" PRIu64 ")\n",
(uint64_t)last_mnt_id, (uint64_t)info.mnt_ns_id);
continue;
}
printf("mnt_id:\t\t%" PRIu64 "\nmnt_parent_id:\t%" PRIu64 "\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n",
(uint64_t)stmnt->mnt_id,
(uint64_t)stmnt->mnt_parent_id,
stmnt->str + stmnt->fs_type,
stmnt->str + stmnt->mnt_root,
stmnt->str + stmnt->mnt_point,
stmnt->str + stmnt->mnt_opts);
free(stmnt);
}
}
exit(0);
}
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