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