1/*
2 *  This program is free software; you can redistribute it and/or
3 *  modify it under the terms of the GNU General Public License as
4 *  published by the Free Software Foundation, version 2 of the
5 *  License.
6 */
7
8#include <linux/module.h>
9#include <linux/version.h>
10#include <linux/nsproxy.h>
11#include <linux/user_namespace.h>
12
13struct user_namespace init_user_ns = {
14	.kref = {
15		.refcount	= ATOMIC_INIT(2),
16	},
17	.root_user = &root_user,
18};
19
20EXPORT_SYMBOL_GPL(init_user_ns);
21
22#ifdef CONFIG_USER_NS
23
24/*
25 * Clone a new ns copying an original user ns, setting refcount to 1
26 * @old_ns: namespace to clone
27 * Return NULL on error (failure to kmalloc), new ns otherwise
28 */
29static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
30{
31	struct user_namespace *ns;
32	struct user_struct *new_user;
33	int n;
34
35	ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
36	if (!ns)
37		return ERR_PTR(-ENOMEM);
38
39	kref_init(&ns->kref);
40
41	for (n = 0; n < UIDHASH_SZ; ++n)
42		INIT_HLIST_HEAD(ns->uidhash_table + n);
43
44	/* Insert new root user.  */
45	ns->root_user = alloc_uid(ns, 0);
46	if (!ns->root_user) {
47		kfree(ns);
48		return ERR_PTR(-ENOMEM);
49	}
50
51	/* Reset current->user with a new one */
52	new_user = alloc_uid(ns, current->uid);
53	if (!new_user) {
54		free_uid(ns->root_user);
55		kfree(ns);
56		return ERR_PTR(-ENOMEM);
57	}
58
59	switch_uid(new_user);
60	return ns;
61}
62
63struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
64{
65	struct user_namespace *new_ns;
66
67	BUG_ON(!old_ns);
68	get_user_ns(old_ns);
69
70	if (!(flags & CLONE_NEWUSER))
71		return old_ns;
72
73	new_ns = clone_user_ns(old_ns);
74
75	put_user_ns(old_ns);
76	return new_ns;
77}
78
79void free_user_ns(struct kref *kref)
80{
81	struct user_namespace *ns;
82
83	ns = container_of(kref, struct user_namespace, kref);
84	release_uids(ns);
85	kfree(ns);
86}
87
88#endif /* CONFIG_USER_NS */
89