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1 | /* | |
2 | * Copyright (C) 2004 IBM Corporation | |
3 | * | |
4 | * Author: Serge Hallyn <serue@us.ibm.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License as | |
8 | * published by the Free Software Foundation, version 2 of the | |
9 | * License. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/uts.h> | |
14 | #include <linux/utsname.h> | |
15 | #include <linux/err.h> | |
16 | #include <linux/slab.h> | |
17 | ||
18 | /* | |
19 | * Clone a new ns copying an original utsname, setting refcount to 1 | |
20 | * @old_ns: namespace to clone | |
21 | * Return NULL on error (failure to kmalloc), new ns otherwise | |
22 | */ | |
23 | static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns) | |
24 | { | |
25 | struct uts_namespace *ns; | |
26 | ||
27 | ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); | |
28 | if (!ns) | |
29 | return ERR_PTR(-ENOMEM); | |
30 | ||
31 | down_read(&uts_sem); | |
32 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); | |
33 | up_read(&uts_sem); | |
34 | kref_init(&ns->kref); | |
35 | return ns; | |
36 | } | |
37 | ||
38 | /* | |
39 | * Copy task tsk's utsname namespace, or clone it if flags | |
40 | * specifies CLONE_NEWUTS. In latter case, changes to the | |
41 | * utsname of this process won't be seen by parent, and vice | |
42 | * versa. | |
43 | */ | |
44 | struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns) | |
45 | { | |
46 | struct uts_namespace *new_ns; | |
47 | ||
48 | BUG_ON(!old_ns); | |
49 | get_uts_ns(old_ns); | |
50 | ||
51 | if (!(flags & CLONE_NEWUTS)) | |
52 | return old_ns; | |
53 | ||
54 | new_ns = clone_uts_ns(old_ns); | |
55 | ||
56 | put_uts_ns(old_ns); | |
57 | return new_ns; | |
58 | } | |
59 | ||
60 | void free_uts_ns(struct kref *kref) | |
61 | { | |
62 | struct uts_namespace *ns; | |
63 | ||
64 | ns = container_of(kref, struct uts_namespace, kref); | |
65 | kfree(ns); | |
66 | } |