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acce292c CLG |
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> | |
1aeb272c | 11 | #include <linux/slab.h> |
acce292c CLG |
12 | #include <linux/user_namespace.h> |
13 | ||
77ec739d SH |
14 | /* |
15 | * Clone a new ns copying an original user ns, setting refcount to 1 | |
16 | * @old_ns: namespace to clone | |
17 | * Return NULL on error (failure to kmalloc), new ns otherwise | |
18 | */ | |
19 | static struct user_namespace *clone_user_ns(struct user_namespace *old_ns) | |
20 | { | |
21 | struct user_namespace *ns; | |
22 | struct user_struct *new_user; | |
23 | int n; | |
24 | ||
25 | ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL); | |
26 | if (!ns) | |
467e9f4b | 27 | return ERR_PTR(-ENOMEM); |
77ec739d SH |
28 | |
29 | kref_init(&ns->kref); | |
30 | ||
31 | for (n = 0; n < UIDHASH_SZ; ++n) | |
735de223 | 32 | INIT_HLIST_HEAD(ns->uidhash_table + n); |
77ec739d SH |
33 | |
34 | /* Insert new root user. */ | |
35 | ns->root_user = alloc_uid(ns, 0); | |
36 | if (!ns->root_user) { | |
37 | kfree(ns); | |
467e9f4b | 38 | return ERR_PTR(-ENOMEM); |
77ec739d SH |
39 | } |
40 | ||
41 | /* Reset current->user with a new one */ | |
42 | new_user = alloc_uid(ns, current->uid); | |
43 | if (!new_user) { | |
44 | free_uid(ns->root_user); | |
45 | kfree(ns); | |
467e9f4b | 46 | return ERR_PTR(-ENOMEM); |
77ec739d SH |
47 | } |
48 | ||
49 | switch_uid(new_user); | |
50 | return ns; | |
51 | } | |
52 | ||
acce292c CLG |
53 | struct user_namespace * copy_user_ns(int flags, struct user_namespace *old_ns) |
54 | { | |
55 | struct user_namespace *new_ns; | |
56 | ||
57 | BUG_ON(!old_ns); | |
58 | get_user_ns(old_ns); | |
59 | ||
77ec739d SH |
60 | if (!(flags & CLONE_NEWUSER)) |
61 | return old_ns; | |
62 | ||
63 | new_ns = clone_user_ns(old_ns); | |
64 | ||
65 | put_user_ns(old_ns); | |
acce292c CLG |
66 | return new_ns; |
67 | } | |
68 | ||
69 | void free_user_ns(struct kref *kref) | |
70 | { | |
71 | struct user_namespace *ns; | |
72 | ||
73 | ns = container_of(kref, struct user_namespace, kref); | |
28f300d2 | 74 | release_uids(ns); |
acce292c CLG |
75 | kfree(ns); |
76 | } | |
6a3fd92e | 77 | EXPORT_SYMBOL(free_user_ns); |