184 lines
4 KiB
C
184 lines
4 KiB
C
/*
|
|
* Copyright (C) 2004 IBM Corporation
|
|
*
|
|
* Author: Serge Hallyn <serue@us.ibm.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation, version 2 of the
|
|
* License.
|
|
*/
|
|
|
|
#include <linux/export.h>
|
|
#include <linux/uts.h>
|
|
#include <linux/utsname.h>
|
|
#include <linux/err.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/cred.h>
|
|
#include <linux/user_namespace.h>
|
|
#include <linux/proc_ns.h>
|
|
#include <linux/sched/task.h>
|
|
|
|
static struct kmem_cache *uts_ns_cache __ro_after_init;
|
|
|
|
static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
|
|
{
|
|
return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
|
|
}
|
|
|
|
static void dec_uts_namespaces(struct ucounts *ucounts)
|
|
{
|
|
dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
|
|
}
|
|
|
|
static struct uts_namespace *create_uts_ns(void)
|
|
{
|
|
struct uts_namespace *uts_ns;
|
|
|
|
uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
|
|
if (uts_ns)
|
|
kref_init(&uts_ns->kref);
|
|
return uts_ns;
|
|
}
|
|
|
|
/*
|
|
* Clone a new ns copying an original utsname, setting refcount to 1
|
|
* @old_ns: namespace to clone
|
|
* Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
|
|
*/
|
|
static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
|
|
struct uts_namespace *old_ns)
|
|
{
|
|
struct uts_namespace *ns;
|
|
struct ucounts *ucounts;
|
|
int err;
|
|
|
|
err = -ENOSPC;
|
|
ucounts = inc_uts_namespaces(user_ns);
|
|
if (!ucounts)
|
|
goto fail;
|
|
|
|
err = -ENOMEM;
|
|
ns = create_uts_ns();
|
|
if (!ns)
|
|
goto fail_dec;
|
|
|
|
err = ns_alloc_inum(&ns->ns);
|
|
if (err)
|
|
goto fail_free;
|
|
|
|
ns->ucounts = ucounts;
|
|
ns->ns.ops = &utsns_operations;
|
|
|
|
down_read(&uts_sem);
|
|
memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
|
|
ns->user_ns = get_user_ns(user_ns);
|
|
up_read(&uts_sem);
|
|
return ns;
|
|
|
|
fail_free:
|
|
kmem_cache_free(uts_ns_cache, ns);
|
|
fail_dec:
|
|
dec_uts_namespaces(ucounts);
|
|
fail:
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
/*
|
|
* Copy task tsk's utsname namespace, or clone it if flags
|
|
* specifies CLONE_NEWUTS. In latter case, changes to the
|
|
* utsname of this process won't be seen by parent, and vice
|
|
* versa.
|
|
*/
|
|
struct uts_namespace *copy_utsname(unsigned long flags,
|
|
struct user_namespace *user_ns, struct uts_namespace *old_ns)
|
|
{
|
|
struct uts_namespace *new_ns;
|
|
|
|
BUG_ON(!old_ns);
|
|
get_uts_ns(old_ns);
|
|
|
|
if (!(flags & CLONE_NEWUTS))
|
|
return old_ns;
|
|
|
|
new_ns = clone_uts_ns(user_ns, old_ns);
|
|
|
|
put_uts_ns(old_ns);
|
|
return new_ns;
|
|
}
|
|
|
|
void free_uts_ns(struct kref *kref)
|
|
{
|
|
struct uts_namespace *ns;
|
|
|
|
ns = container_of(kref, struct uts_namespace, kref);
|
|
dec_uts_namespaces(ns->ucounts);
|
|
put_user_ns(ns->user_ns);
|
|
ns_free_inum(&ns->ns);
|
|
kmem_cache_free(uts_ns_cache, ns);
|
|
}
|
|
|
|
static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
|
|
{
|
|
return container_of(ns, struct uts_namespace, ns);
|
|
}
|
|
|
|
static struct ns_common *utsns_get(struct task_struct *task)
|
|
{
|
|
struct uts_namespace *ns = NULL;
|
|
struct nsproxy *nsproxy;
|
|
|
|
task_lock(task);
|
|
nsproxy = task->nsproxy;
|
|
if (nsproxy) {
|
|
ns = nsproxy->uts_ns;
|
|
get_uts_ns(ns);
|
|
}
|
|
task_unlock(task);
|
|
|
|
return ns ? &ns->ns : NULL;
|
|
}
|
|
|
|
static void utsns_put(struct ns_common *ns)
|
|
{
|
|
put_uts_ns(to_uts_ns(ns));
|
|
}
|
|
|
|
static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
|
|
{
|
|
struct uts_namespace *ns = to_uts_ns(new);
|
|
|
|
if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
|
|
!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
get_uts_ns(ns);
|
|
put_uts_ns(nsproxy->uts_ns);
|
|
nsproxy->uts_ns = ns;
|
|
return 0;
|
|
}
|
|
|
|
static struct user_namespace *utsns_owner(struct ns_common *ns)
|
|
{
|
|
return to_uts_ns(ns)->user_ns;
|
|
}
|
|
|
|
const struct proc_ns_operations utsns_operations = {
|
|
.name = "uts",
|
|
.type = CLONE_NEWUTS,
|
|
.get = utsns_get,
|
|
.put = utsns_put,
|
|
.install = utsns_install,
|
|
.owner = utsns_owner,
|
|
};
|
|
|
|
void __init uts_ns_init(void)
|
|
{
|
|
uts_ns_cache = kmem_cache_create_usercopy(
|
|
"uts_namespace", sizeof(struct uts_namespace), 0,
|
|
SLAB_PANIC|SLAB_ACCOUNT,
|
|
offsetof(struct uts_namespace, name),
|
|
sizeof_field(struct uts_namespace, name),
|
|
NULL);
|
|
}
|