// SPDX-License-Identifier: GPL-2.0
#include <linux/mount.h>
#include <linux/pseudo_fs.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/ktime.h>
#include <linux/seq_file.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <linux/nsfs.h>
#include <linux/uaccess.h>
#include <linux/mnt_namespace.h>
#include "mount.h"
#include "internal.h"
static struct vfsmount *nsfs_mnt;
static long ns_ioctl(struct file *filp, unsigned int ioctl,
unsigned long arg);
static const struct file_operations ns_file_operations = {
.unlocked_ioctl = ns_ioctl,
.compat_ioctl = compat_ptr_ioctl,
};
static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
{
struct inode *inode = d_inode(dentry);
struct ns_common *ns = inode->i_private;
const struct proc_ns_operations *ns_ops = ns->ops;
return dynamic_dname(buffer, buflen, "%s:[%lu]",
ns_ops->name, inode->i_ino);
}
const struct dentry_operations ns_dentry_operations = {
.d_delete = always_delete_dentry,
.d_dname = ns_dname,
.d_prune = stashed_dentry_prune,
};
static void nsfs_evict(struct inode *inode)
{
struct ns_common *ns = inode->i_private;
clear_inode(inode);
ns->ops->put(ns);
}
int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
void *private_data)
{
struct ns_common *ns;
ns = ns_get_cb(private_data);
if (!ns)
return -ENOENT;
return path_from_stashed(&ns->stashed, nsfs_mnt, ns, path);
}
struct ns_get_path_task_args {
const struct proc_ns_operations *ns_ops;
struct task_struct *task;
};
static struct ns_common *ns_get_path_task(void *private_data)
{
struct ns_get_path_task_args *args = private_data;
return args->ns_ops->get(args->task);
}
int ns_get_path(struct path *path, struct task_struct *task,
const struct proc_ns_operations *ns_ops)
{
struct ns_get_path_task_args args = {
.ns_ops = ns_ops,
.task = task,
};
return ns_get_path_cb(path, ns_get_path_task, &args);
}
/**
* open_namespace - open a namespace
* @ns: the namespace to open
*
* This will consume a reference to @ns indendent of success or failure.
*
* Return: A file descriptor on success or a negative error code on failure.
*/
int open_namespace(struct ns_common *ns)
{
struct path path __free(path_put) = {};
struct file *f;
int err;
/* call first to consume reference */
err = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path);
if (err < 0)
return err;
CLASS(get_unused_fd, fd)(O_CLOEXEC);
if (fd < 0)
return fd;
f = dentry_open(&path, O_RDONLY, current_cred());
if (IS_ERR(f))
return PTR_ERR(f);
fd_install(fd, f);
return take_fd(fd);
}
int open_related_ns(struct ns_common *ns,
struct ns_common *(*get_ns)(struct ns_common *ns))
{
struct ns_common *relative;
relative = get_ns(ns);
if (IS_ERR(relative))
return PTR_ERR(relative);
return open_namespace(relative);
}
EXPORT_SYMBOL_GPL(open_related_ns);
static int copy_ns_info_to_user(const struct mnt_namespace *mnt_ns,
struct mnt_ns_info __user *uinfo, size_t usize,
struct mnt_ns_info *kinfo)
{
/*
* If userspace and the kernel have the same struct size it can just
* be copied. If userspace provides an older struct, only the bits that
* userspace knows about will be copied. If userspace provides a new
* struct, only the bits that the kernel knows aobut will be copied and
* the size value will be set to the size the kernel knows about.
*/
kinfo->size = min(usize, sizeof(*kinfo));
kinfo->mnt_ns_id = mnt_ns->seq;
kinfo->nr_mounts = READ_ONCE(mnt_ns->nr_mounts);
/* Subtract the root mount of the mount namespace. */
if (kinfo->nr_mounts)
kinfo->nr_mounts--;
if (copy_to_user(uinfo, kinfo, kinfo->size))
return -EFAULT;
return 0;
}
static long ns_ioctl(struct file *filp, unsigned int ioctl,
unsigned long arg)
{
struct user_namespace *user_ns;
struct pid_namespace *pid_ns;
struct task_struct *tsk;
struct ns_common *ns = get_proc_ns(file_inode(filp));
struct mnt_namespace *mnt_ns;
bool previous = false;
uid_t __user *argp;
uid_t uid;
int ret;
switch (ioctl) {
case NS_GET_USERNS:
return open_related_ns(ns, ns_get_owner);
case NS_GET_PARENT:
if (!ns->ops->get_parent)
return -EINVAL;
return open_related_ns(ns, ns->ops->get_parent);
case NS_GET_NSTYPE:
return ns->ops->type;
case NS_GET_OWNER_UID:
if (ns->ops->type != CLONE_NEWUSER)
return -EINVAL;
user_ns = container_of(ns, struct user_namespace, ns);
argp = (uid_t __user *) arg;
uid = from_kuid_munged(current_user_ns(), user_ns->owner);
return put_user(uid, argp);
case NS_GET_MNTNS_ID: {
__u64 __user *idp;
__u64 id;
if (ns->ops->type != CLONE_NEWNS)
return -EINVAL;
mnt_ns = container_of(ns, struct mnt_namespace, ns);
idp = (__u64 __user *)arg;
id = mnt_ns->seq;
return put_user(id, idp);
}
case NS_GET_PID_FROM_PIDNS:
fallthrough;
case NS_GET_TGID_FROM_PIDNS:
fallthrough;
case NS_GET_PID_IN_PIDNS:
fallthrough;
case NS_GET_TGID_IN_PIDNS: {
if (ns->ops->type != CLONE_NEWPID)
return -EINVAL;
ret = -ESRCH;
pid_ns = container_of(ns, struct pid_namespace, ns);
guard(rcu)();
if (ioctl == NS_GET_PID_IN_PIDNS ||
ioctl == NS_GET_TGID_IN_PIDNS)
tsk = find_task_by_vpid(arg);
else
tsk = find_task_by_pid_ns(arg, pid_ns);
if (!tsk)
break;
switch (ioctl) {
case NS_GET_PID_FROM_PIDNS:
ret = task_pid_vnr(tsk);
break;
case NS_GET_TGID_FROM_PIDNS:
ret = task_tgid_vnr(tsk);
break;
case NS_GET_PID_IN_PIDNS:
ret = task_pid_nr_ns(tsk, pid_ns);
break;
case NS_GET_TGID_IN_PIDNS:
ret = task_tgid_nr_ns(tsk, pid_ns);
break;
default:
ret = 0;
break;
}
if (!ret)
ret = -ESRCH;
return ret;
}
}
/* extensible ioctls */
switch (_IOC_NR(ioctl)) {
case _IOC_NR(NS_MNT_GET_INFO): {
struct mnt_ns_info kinfo = {};
struct mnt_ns_info __user *uinfo = (struct mnt_ns_info __user *)arg;
size_t usize = _IOC_SIZE(ioctl);
if (ns->ops->type != CLONE_NEWNS)
return -EINVAL;
if (!uinfo)
return -EINVAL;
if (usize < MNT_NS_INFO_SIZE_VER0)
return -EINVAL;
return copy_ns_info_to_user(to_mnt_ns(ns), uinfo, usize, &kinfo);
}
case _IOC_NR(NS_MNT_GET_PREV):
previous = true;
fallthrough;
case _IOC_NR(NS_MNT_GET_NEXT): {
struct mnt_ns_info kinfo = {};
struct mnt_ns_info __user *uinfo = (struct mnt_ns_info __user *)arg;
struct path path __free(path_put) = {};
struct file *f __free(fput) = NULL;
size_t usize = _IOC_SIZE(ioctl);
if (ns->ops->type != CLONE_NEWNS)
return -EINVAL;
if (usize < MNT_NS_INFO_SIZE_VER0)
return -EINVAL;
if (previous)
mnt_ns = lookup_prev_mnt_ns(to_mnt_ns(ns));
else
mnt_ns = lookup_next_mnt_ns(to_mnt_ns(ns));
if (IS_ERR(mnt_ns))
return PTR_ERR(mnt_ns);
ns = to_ns_common(mnt_ns);
/* Transfer ownership of @mnt_ns reference to @path. */
ret = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path);
if (ret)
return ret;
CLASS(get_unused_fd, fd)(O_CLOEXEC);
if (fd < 0)
return fd;
f = dentry_open(&path, O_RDONLY, current_cred());
if (IS_ERR(f))
return PTR_ERR(f);
if (uinfo) {
/*
* If @uinfo is passed return all information about the
* mount namespace as well.
*/
ret = copy_ns_info_to_user(to_mnt_ns(ns), uinfo, usize, &kinfo);
if (ret)
return ret;
}
/* Transfer reference of @f to caller's fdtable. */
fd_install(fd, no_free_ptr(f));
/* File descriptor is live so hand it off to the caller. */
return take_fd(fd);
}
default:
ret = -ENOTTY;
}
return ret;
}
int ns_get_name(char *buf, size_t size, struct task_struct *task,
const struct proc_ns_operations *ns_ops)
{
struct ns_common *ns;
int res = -ENOENT;
const char *name;
ns = ns_ops->get(task);
if (ns) {
name = ns_ops->real_ns_name ? : ns_ops->name;
res = snprintf(buf, size, "%s:[%u]", name, ns->inum);
ns_ops->put(ns);
}
return res;
}
bool proc_ns_file(const struct file *file)
{
return file->f_op == &ns_file_operations;
}
/**
* ns_match() - Returns true if current namespace matches dev/ino provided.
* @ns: current namespace
* @dev: dev_t from nsfs that will be matched against current nsfs
* @ino: ino_t from nsfs that will be matched against current nsfs
*
* Return: true if dev and ino matches the current nsfs.
*/
bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
{
return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
}
static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
const struct ns_common *ns = inode->i_private;
const struct proc_ns_operations *ns_ops = ns->ops;
seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
return 0;
}
static const struct super_operations nsfs_ops = {
.statfs = simple_statfs,
.evict_inode = nsfs_evict,
.show_path = nsfs_show_path,
};
static int nsfs_init_inode(struct inode *inode, void *data)
{
struct ns_common *ns = data;
inode->i_private = data;
inode->i_mode |= S_IRUGO;
inode->i_fop = &ns_file_operations;
inode->i_ino = ns->inum;
return 0;
}
static void nsfs_put_data(void *data)
{
struct ns_common *ns = data;
ns->ops->put(ns);
}
static const struct stashed_operations nsfs_stashed_ops = {
.init_inode = nsfs_init_inode,
.put_data = nsfs_put_data,
};
static int nsfs_init_fs_context(struct fs_context *fc)
{
struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
if (!ctx)
return -ENOMEM;
ctx->ops = &nsfs_ops;
ctx->dops = &ns_dentry_operations;
fc->s_fs_info = (void *)&nsfs_stashed_ops;
return 0;
}
static struct file_system_type nsfs = {
.name = "nsfs",
.init_fs_context = nsfs_init_fs_context,
.kill_sb = kill_anon_super,
};
void __init nsfs_init(void)
{
nsfs_mnt = kern_mount(&nsfs);
if (IS_ERR(nsfs_mnt))
panic("can't set nsfs up\n");
nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;
}
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