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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/nsproxy.h> | |
10 | #include <linux/slab.h> | |
11 | #include <linux/user_namespace.h> | |
12 | #include <linux/cred.h> | |
13 | ||
14 | /* | |
15 | * Create a new user namespace, deriving the creator from the user in the | |
16 | * passed credentials, and replacing that user with the new root user for the | |
17 | * new namespace. | |
18 | * | |
19 | * This is called by copy_creds(), which will finish setting the target task's | |
20 | * credentials. | |
21 | */ | |
22 | int create_user_ns(struct cred *new) | |
23 | { | |
24 | struct user_namespace *ns; | |
25 | struct user_struct *root_user; | |
26 | int n; | |
27 | ||
28 | ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL); | |
29 | if (!ns) | |
30 | return -ENOMEM; | |
31 | ||
32 | kref_init(&ns->kref); | |
33 | ||
34 | for (n = 0; n < UIDHASH_SZ; ++n) | |
35 | INIT_HLIST_HEAD(ns->uidhash_table + n); | |
36 | ||
37 | /* Alloc new root user. */ | |
38 | root_user = alloc_uid(ns, 0); | |
39 | if (!root_user) { | |
40 | kfree(ns); | |
41 | return -ENOMEM; | |
42 | } | |
43 | ||
44 | /* set the new root user in the credentials under preparation */ | |
45 | ns->creator = new->user; | |
46 | new->user = root_user; | |
47 | new->uid = new->euid = new->suid = new->fsuid = 0; | |
48 | new->gid = new->egid = new->sgid = new->fsgid = 0; | |
49 | put_group_info(new->group_info); | |
50 | new->group_info = get_group_info(&init_groups); | |
51 | #ifdef CONFIG_KEYS | |
52 | key_put(new->request_key_auth); | |
53 | new->request_key_auth = NULL; | |
54 | #endif | |
55 | /* tgcred will be cleared in our caller bc CLONE_THREAD won't be set */ | |
56 | ||
57 | /* alloc_uid() incremented the userns refcount. Just set it to 1 */ | |
58 | kref_set(&ns->kref, 1); | |
59 | ||
60 | return 0; | |
61 | } | |
62 | ||
63 | /* | |
64 | * Deferred destructor for a user namespace. This is required because | |
65 | * free_user_ns() may be called with uidhash_lock held, but we need to call | |
66 | * back to free_uid() which will want to take the lock again. | |
67 | */ | |
68 | static void free_user_ns_work(struct work_struct *work) | |
69 | { | |
70 | struct user_namespace *ns = | |
71 | container_of(work, struct user_namespace, destroyer); | |
72 | free_uid(ns->creator); | |
73 | kfree(ns); | |
74 | } | |
75 | ||
76 | void free_user_ns(struct kref *kref) | |
77 | { | |
78 | struct user_namespace *ns = | |
79 | container_of(kref, struct user_namespace, kref); | |
80 | ||
81 | INIT_WORK(&ns->destroyer, free_user_ns_work); | |
82 | schedule_work(&ns->destroyer); | |
83 | } | |
84 | EXPORT_SYMBOL(free_user_ns); |