usb/host: introduce USB_ARCH_HAS_XHCI
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / user_namespace.c
blob9da289c34f22f161974e6b6b5eaa753d8af960f3
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/nsproxy.h>
10 #include <linux/slab.h>
11 #include <linux/user_namespace.h>
12 #include <linux/highuid.h>
13 #include <linux/cred.h>
15 static struct kmem_cache *user_ns_cachep __read_mostly;
18 * Create a new user namespace, deriving the creator from the user in the
19 * passed credentials, and replacing that user with the new root user for the
20 * new namespace.
22 * This is called by copy_creds(), which will finish setting the target task's
23 * credentials.
25 int create_user_ns(struct cred *new)
27 struct user_namespace *ns;
28 struct user_struct *root_user;
29 int n;
31 ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);
32 if (!ns)
33 return -ENOMEM;
35 kref_init(&ns->kref);
37 for (n = 0; n < UIDHASH_SZ; ++n)
38 INIT_HLIST_HEAD(ns->uidhash_table + n);
40 /* Alloc new root user. */
41 root_user = alloc_uid(ns, 0);
42 if (!root_user) {
43 kmem_cache_free(user_ns_cachep, ns);
44 return -ENOMEM;
47 /* set the new root user in the credentials under preparation */
48 ns->creator = new->user;
49 new->user = root_user;
50 new->uid = new->euid = new->suid = new->fsuid = 0;
51 new->gid = new->egid = new->sgid = new->fsgid = 0;
52 put_group_info(new->group_info);
53 new->group_info = get_group_info(&init_groups);
54 #ifdef CONFIG_KEYS
55 key_put(new->request_key_auth);
56 new->request_key_auth = NULL;
57 #endif
58 /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
60 /* root_user holds a reference to ns, our reference can be dropped */
61 put_user_ns(ns);
63 return 0;
67 * Deferred destructor for a user namespace. This is required because
68 * free_user_ns() may be called with uidhash_lock held, but we need to call
69 * back to free_uid() which will want to take the lock again.
71 static void free_user_ns_work(struct work_struct *work)
73 struct user_namespace *ns =
74 container_of(work, struct user_namespace, destroyer);
75 free_uid(ns->creator);
76 kmem_cache_free(user_ns_cachep, ns);
79 void free_user_ns(struct kref *kref)
81 struct user_namespace *ns =
82 container_of(kref, struct user_namespace, kref);
84 INIT_WORK(&ns->destroyer, free_user_ns_work);
85 schedule_work(&ns->destroyer);
87 EXPORT_SYMBOL(free_user_ns);
89 uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid)
91 struct user_namespace *tmp;
93 if (likely(to == cred->user->user_ns))
94 return uid;
97 /* Is cred->user the creator of the target user_ns
98 * or the creator of one of it's parents?
100 for ( tmp = to; tmp != &init_user_ns;
101 tmp = tmp->creator->user_ns ) {
102 if (cred->user == tmp->creator) {
103 return (uid_t)0;
107 /* No useful relationship so no mapping */
108 return overflowuid;
111 gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid)
113 struct user_namespace *tmp;
115 if (likely(to == cred->user->user_ns))
116 return gid;
118 /* Is cred->user the creator of the target user_ns
119 * or the creator of one of it's parents?
121 for ( tmp = to; tmp != &init_user_ns;
122 tmp = tmp->creator->user_ns ) {
123 if (cred->user == tmp->creator) {
124 return (gid_t)0;
128 /* No useful relationship so no mapping */
129 return overflowgid;
132 static __init int user_namespaces_init(void)
134 user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
135 return 0;
137 module_init(user_namespaces_init);