sched: reintroduce topology.h tunings
[wrt350n-kernel.git] / kernel / user_namespace.c
blob7af90fc4f0fd3d870c1f5dbb3b0771fc16bbc5a4
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 */
8 #include <linux/module.h>
9 #include <linux/version.h>
10 #include <linux/nsproxy.h>
11 #include <linux/user_namespace.h>
13 struct user_namespace init_user_ns = {
14 .kref = {
15 .refcount = ATOMIC_INIT(2),
17 .root_user = &root_user,
20 EXPORT_SYMBOL_GPL(init_user_ns);
22 #ifdef CONFIG_USER_NS
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
29 static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
31 struct user_namespace *ns;
32 struct user_struct *new_user;
33 int n;
35 ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
36 if (!ns)
37 return ERR_PTR(-ENOMEM);
39 kref_init(&ns->kref);
41 for (n = 0; n < UIDHASH_SZ; ++n)
42 INIT_HLIST_HEAD(ns->uidhash_table + n);
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);
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);
59 switch_uid(new_user);
60 return ns;
63 struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns)
65 struct user_namespace *new_ns;
67 BUG_ON(!old_ns);
68 get_user_ns(old_ns);
70 if (!(flags & CLONE_NEWUSER))
71 return old_ns;
73 new_ns = clone_user_ns(old_ns);
75 put_user_ns(old_ns);
76 return new_ns;
79 void free_user_ns(struct kref *kref)
81 struct user_namespace *ns;
83 ns = container_of(kref, struct user_namespace, kref);
84 release_uids(ns);
85 kfree(ns);
88 #endif /* CONFIG_USER_NS */