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
8 #include <linux/export.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
22 * This is called by copy_creds(), which will finish setting the target task's
25 int create_user_ns(struct cred *new)
27 struct user_namespace *ns, *parent_ns = new->user_ns;
28 struct user_struct *root_user;
31 ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);
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);
43 kmem_cache_free(user_ns_cachep, ns);
47 /* set the new root user in the credentials under preparation */
48 ns->parent = parent_ns;
49 ns->creator = new->user;
50 new->user = root_user;
51 new->uid = new->euid = new->suid = new->fsuid = 0;
52 new->gid = new->egid = new->sgid = new->fsgid = 0;
53 put_group_info(new->group_info);
54 new->group_info = get_group_info(&init_groups);
56 key_put(new->request_key_auth);
57 new->request_key_auth = NULL;
59 /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */
61 /* Leave the reference to our user_ns with the new cred */
68 * Deferred destructor for a user namespace. This is required because
69 * free_user_ns() may be called with uidhash_lock held, but we need to call
70 * back to free_uid() which will want to take the lock again.
72 static void free_user_ns_work(struct work_struct *work)
74 struct user_namespace *parent, *ns =
75 container_of(work, struct user_namespace, destroyer);
77 free_uid(ns->creator);
78 kmem_cache_free(user_ns_cachep, ns);
82 void free_user_ns(struct kref *kref)
84 struct user_namespace *ns =
85 container_of(kref, struct user_namespace, kref);
87 INIT_WORK(&ns->destroyer, free_user_ns_work);
88 schedule_work(&ns->destroyer);
90 EXPORT_SYMBOL(free_user_ns);
92 uid_t user_ns_map_uid(struct user_namespace *to, const struct cred *cred, uid_t uid)
94 struct user_namespace *tmp;
96 if (likely(to == cred->user_ns))
100 /* Is cred->user the creator of the target user_ns
101 * or the creator of one of it's parents?
103 for ( tmp = to; tmp != &init_user_ns; tmp = tmp->parent ) {
104 if (cred->user == tmp->creator) {
109 /* No useful relationship so no mapping */
113 gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t gid)
115 struct user_namespace *tmp;
117 if (likely(to == cred->user_ns))
120 /* Is cred->user the creator of the target user_ns
121 * or the creator of one of it's parents?
123 for ( tmp = to; tmp != &init_user_ns; tmp = tmp->parent ) {
124 if (cred->user == tmp->creator) {
129 /* No useful relationship so no mapping */
133 static __init int user_namespaces_init(void)
135 user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
138 module_init(user_namespaces_init);