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// SPDX-License-Identifier: BSD-2-Clause
/*
* Copyright (c) 2021 Klara Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/kmem.h>
#include <linux/file.h>
#include <linux/magic.h>
#include <sys/zone.h>
#include <sys/string.h>
#if defined(CONFIG_USER_NS)
#include <linux/statfs.h>
#include <linux/proc_ns.h>
#endif
#include <sys/mutex.h>
static kmutex_t zone_datasets_lock;
static struct list_head zone_datasets;
typedef struct zone_datasets {
struct list_head zds_list; /* zone_datasets linkage */
struct user_namespace *zds_userns; /* namespace reference */
struct list_head zds_datasets; /* datasets for the namespace */
} zone_datasets_t;
typedef struct zone_dataset {
struct list_head zd_list; /* zone_dataset linkage */
size_t zd_dsnamelen; /* length of name */
char zd_dsname[]; /* name of the member dataset */
} zone_dataset_t;
#ifdef CONFIG_USER_NS
/*
* Returns:
* - 0 on success
* - EBADF if it cannot open the provided file descriptor
* - ENOTTY if the file itself is a not a user namespace file. We want to
* intercept this error in the ZFS layer. We cannot just return one of the
* ZFS_ERR_* errors here as we want to preserve the seperation of the ZFS
* and the SPL layers.
*/
static int
user_ns_get(int fd, struct user_namespace **userns)
{
struct kstatfs st;
struct file *nsfile;
struct ns_common *ns;
int error;
if ((nsfile = fget(fd)) == NULL)
return (EBADF);
if (vfs_statfs(&nsfile->f_path, &st) != 0) {
error = ENOTTY;
goto done;
}
if (st.f_type != NSFS_MAGIC) {
error = ENOTTY;
goto done;
}
ns = get_proc_ns(file_inode(nsfile));
if (ns->ops->type != CLONE_NEWUSER) {
error = ENOTTY;
goto done;
}
*userns = container_of(ns, struct user_namespace, ns);
error = 0;
done:
fput(nsfile);
return (error);
}
#endif /* CONFIG_USER_NS */
static unsigned int
user_ns_zoneid(struct user_namespace *user_ns)
{
unsigned int r;
r = user_ns->ns.inum;
return (r);
}
static struct zone_datasets *
zone_datasets_lookup(unsigned int nsinum)
{
zone_datasets_t *zds;
list_for_each_entry(zds, &zone_datasets, zds_list) {
if (user_ns_zoneid(zds->zds_userns) == nsinum)
return (zds);
}
return (NULL);
}
#ifdef CONFIG_USER_NS
static struct zone_dataset *
zone_dataset_lookup(zone_datasets_t *zds, const char *dataset, size_t dsnamelen)
{
zone_dataset_t *zd;
list_for_each_entry(zd, &zds->zds_datasets, zd_list) {
if (zd->zd_dsnamelen != dsnamelen)
continue;
if (strncmp(zd->zd_dsname, dataset, dsnamelen) == 0)
return (zd);
}
return (NULL);
}
static int
zone_dataset_cred_check(cred_t *cred)
{
if (!uid_eq(cred->uid, GLOBAL_ROOT_UID))
return (EPERM);
return (0);
}
#endif /* CONFIG_USER_NS */
static int
zone_dataset_name_check(const char *dataset, size_t *dsnamelen)
{
if (dataset[0] == '\0' || dataset[0] == '/')
return (ENOENT);
*dsnamelen = strlen(dataset);
/* Ignore trailing slash, if supplied. */
if (dataset[*dsnamelen - 1] == '/')
(*dsnamelen)--;
return (0);
}
int
zone_dataset_attach(cred_t *cred, const char *dataset, int userns_fd)
{
#ifdef CONFIG_USER_NS
struct user_namespace *userns;
zone_datasets_t *zds;
zone_dataset_t *zd;
int error;
size_t dsnamelen;
if ((error = zone_dataset_cred_check(cred)) != 0)
return (error);
if ((error = zone_dataset_name_check(dataset, &dsnamelen)) != 0)
return (error);
if ((error = user_ns_get(userns_fd, &userns)) != 0)
return (error);
mutex_enter(&zone_datasets_lock);
zds = zone_datasets_lookup(user_ns_zoneid(userns));
if (zds == NULL) {
zds = kmem_alloc(sizeof (zone_datasets_t), KM_SLEEP);
INIT_LIST_HEAD(&zds->zds_list);
INIT_LIST_HEAD(&zds->zds_datasets);
zds->zds_userns = userns;
/*
* Lock the namespace by incresing its refcount to prevent
* the namespace ID from being reused.
*/
get_user_ns(userns);
list_add_tail(&zds->zds_list, &zone_datasets);
} else {
zd = zone_dataset_lookup(zds, dataset, dsnamelen);
if (zd != NULL) {
mutex_exit(&zone_datasets_lock);
return (EEXIST);
}
}
zd = kmem_alloc(sizeof (zone_dataset_t) + dsnamelen + 1, KM_SLEEP);
zd->zd_dsnamelen = dsnamelen;
strlcpy(zd->zd_dsname, dataset, dsnamelen + 1);
INIT_LIST_HEAD(&zd->zd_list);
list_add_tail(&zd->zd_list, &zds->zds_datasets);
mutex_exit(&zone_datasets_lock);
return (0);
#else
return (ENXIO);
#endif /* CONFIG_USER_NS */
}
EXPORT_SYMBOL(zone_dataset_attach);
int
zone_dataset_detach(cred_t *cred, const char *dataset, int userns_fd)
{
#ifdef CONFIG_USER_NS
struct user_namespace *userns;
zone_datasets_t *zds;
zone_dataset_t *zd;
int error;
size_t dsnamelen;
if ((error = zone_dataset_cred_check(cred)) != 0)
return (error);
if ((error = zone_dataset_name_check(dataset, &dsnamelen)) != 0)
return (error);
if ((error = user_ns_get(userns_fd, &userns)) != 0)
return (error);
mutex_enter(&zone_datasets_lock);
zds = zone_datasets_lookup(user_ns_zoneid(userns));
if (zds != NULL)
zd = zone_dataset_lookup(zds, dataset, dsnamelen);
if (zds == NULL || zd == NULL) {
mutex_exit(&zone_datasets_lock);
return (ENOENT);
}
list_del(&zd->zd_list);
kmem_free(zd, sizeof (*zd) + zd->zd_dsnamelen + 1);
/* Prune the namespace entry if it has no more delegations. */
if (list_empty(&zds->zds_datasets)) {
/*
* Decrease the refcount now that the namespace is no longer
* used. It is no longer necessary to prevent the namespace ID
* from being reused.
*/
put_user_ns(userns);
list_del(&zds->zds_list);
kmem_free(zds, sizeof (*zds));
}
mutex_exit(&zone_datasets_lock);
return (0);
#else
return (ENXIO);
#endif /* CONFIG_USER_NS */
}
EXPORT_SYMBOL(zone_dataset_detach);
/*
* A dataset is visible if:
* - It is a parent of a namespace entry.
* - It is one of the namespace entries.
* - It is a child of a namespace entry.
*
* A dataset is writable if:
* - It is one of the namespace entries.
* - It is a child of a namespace entry.
*
* The parent datasets of namespace entries are visible and
* read-only to provide a path back to the root of the pool.
*/
int
zone_dataset_visible(const char *dataset, int *write)
{
zone_datasets_t *zds;
zone_dataset_t *zd;
size_t dsnamelen, zd_len;
int visible;
/* Default to read-only, in case visible is returned. */
if (write != NULL)
*write = 0;
if (zone_dataset_name_check(dataset, &dsnamelen) != 0)
return (0);
if (INGLOBALZONE(curproc)) {
if (write != NULL)
*write = 1;
return (1);
}
mutex_enter(&zone_datasets_lock);
zds = zone_datasets_lookup(crgetzoneid(curproc->cred));
if (zds == NULL) {
mutex_exit(&zone_datasets_lock);
return (0);
}
visible = 0;
list_for_each_entry(zd, &zds->zds_datasets, zd_list) {
zd_len = strlen(zd->zd_dsname);
if (zd_len > dsnamelen) {
/*
* The name of the namespace entry is longer than that
* of the dataset, so it could be that the dataset is a
* parent of the namespace entry.
*/
visible = memcmp(zd->zd_dsname, dataset,
dsnamelen) == 0 &&
zd->zd_dsname[dsnamelen] == '/';
if (visible)
break;
} else if (zd_len == dsnamelen) {
/*
* The name of the namespace entry is as long as that
* of the dataset, so perhaps the dataset itself is the
* namespace entry.
*/
visible = memcmp(zd->zd_dsname, dataset, zd_len) == 0;
if (visible) {
if (write != NULL)
*write = 1;
break;
}
} else {
/*
* The name of the namespace entry is shorter than that
* of the dataset, so perhaps the dataset is a child of
* the namespace entry.
*/
visible = memcmp(zd->zd_dsname, dataset,
zd_len) == 0 && dataset[zd_len] == '/';
if (visible) {
if (write != NULL)
*write = 1;
break;
}
}
}
mutex_exit(&zone_datasets_lock);
return (visible);
}
EXPORT_SYMBOL(zone_dataset_visible);
unsigned int
global_zoneid(void)
{
unsigned int z = 0;
#if defined(CONFIG_USER_NS)
z = user_ns_zoneid(&init_user_ns);
#endif
return (z);
}
EXPORT_SYMBOL(global_zoneid);
unsigned int
crgetzoneid(const cred_t *cr)
{
unsigned int r = 0;
#if defined(CONFIG_USER_NS)
r = user_ns_zoneid(cr->user_ns);
#endif
return (r);
}
EXPORT_SYMBOL(crgetzoneid);
boolean_t
inglobalzone(proc_t *proc)
{
#if defined(CONFIG_USER_NS)
return (proc->cred->user_ns == &init_user_ns);
#else
return (B_TRUE);
#endif
}
EXPORT_SYMBOL(inglobalzone);
int
spl_zone_init(void)
{
mutex_init(&zone_datasets_lock, NULL, MUTEX_DEFAULT, NULL);
INIT_LIST_HEAD(&zone_datasets);
return (0);
}
void
spl_zone_fini(void)
{
zone_datasets_t *zds;
zone_dataset_t *zd;
/*
* It would be better to assert an empty zone_datasets, but since
* there's no automatic mechanism for cleaning them up if the user
* namespace is destroyed, just do it here, since spl is about to go
* out of context.
*/
while (!list_empty(&zone_datasets)) {
zds = list_entry(zone_datasets.next, zone_datasets_t, zds_list);
while (!list_empty(&zds->zds_datasets)) {
zd = list_entry(zds->zds_datasets.next,
zone_dataset_t, zd_list);
list_del(&zd->zd_list);
kmem_free(zd, sizeof (*zd) + zd->zd_dsnamelen + 1);
}
put_user_ns(zds->zds_userns);
list_del(&zds->zds_list);
kmem_free(zds, sizeof (*zds));
}
mutex_destroy(&zone_datasets_lock);
}
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