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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 | static struct uts_namespace *create_uts_ns(void) | |
19 | { | |
20 | struct uts_namespace *uts_ns; | |
21 | ||
22 | uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); | |
23 | if (uts_ns) | |
24 | kref_init(&uts_ns->kref); | |
25 | return uts_ns; | |
26 | } | |
27 | ||
28 | /* | |
29 | * Clone a new ns copying an original utsname, setting refcount to 1 | |
30 | * @old_ns: namespace to clone | |
31 | * Return NULL on error (failure to kmalloc), new ns otherwise | |
32 | */ | |
33 | static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns) | |
34 | { | |
35 | struct uts_namespace *ns; | |
36 | ||
37 | ns = create_uts_ns(); | |
38 | if (!ns) | |
39 | return ERR_PTR(-ENOMEM); | |
40 | ||
41 | down_read(&uts_sem); | |
42 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); | |
43 | up_read(&uts_sem); | |
44 | return ns; | |
45 | } | |
46 | ||
47 | /* | |
48 | * Copy task tsk's utsname namespace, or clone it if flags | |
49 | * specifies CLONE_NEWUTS. In latter case, changes to the | |
50 | * utsname of this process won't be seen by parent, and vice | |
51 | * versa. | |
52 | */ | |
53 | struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns) | |
54 | { | |
55 | struct uts_namespace *new_ns; | |
56 | ||
57 | BUG_ON(!old_ns); | |
58 | get_uts_ns(old_ns); | |
59 | ||
60 | if (!(flags & CLONE_NEWUTS)) | |
61 | return old_ns; | |
62 | ||
63 | new_ns = clone_uts_ns(old_ns); | |
64 | ||
65 | put_uts_ns(old_ns); | |
66 | return new_ns; | |
67 | } | |
68 | ||
69 | void free_uts_ns(struct kref *kref) | |
70 | { | |
71 | struct uts_namespace *ns; | |
72 | ||
73 | ns = container_of(kref, struct uts_namespace, kref); | |
74 | kfree(ns); | |
75 | } |