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4865ecf1 SH |
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> | |
467e9f4b | 15 | #include <linux/err.h> |
1aeb272c | 16 | #include <linux/slab.h> |
59607db3 | 17 | #include <linux/user_namespace.h> |
4865ecf1 | 18 | |
4c2a7e72 AD |
19 | static struct uts_namespace *create_uts_ns(void) |
20 | { | |
21 | struct uts_namespace *uts_ns; | |
22 | ||
23 | uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); | |
24 | if (uts_ns) | |
25 | kref_init(&uts_ns->kref); | |
26 | return uts_ns; | |
27 | } | |
28 | ||
071df104 SH |
29 | /* |
30 | * Clone a new ns copying an original utsname, setting refcount to 1 | |
31 | * @old_ns: namespace to clone | |
32 | * Return NULL on error (failure to kmalloc), new ns otherwise | |
33 | */ | |
34 | static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns) | |
35 | { | |
36 | struct uts_namespace *ns; | |
37 | ||
4c2a7e72 | 38 | ns = create_uts_ns(); |
467e9f4b CLG |
39 | if (!ns) |
40 | return ERR_PTR(-ENOMEM); | |
41 | ||
efc63c4f | 42 | down_read(&uts_sem); |
467e9f4b | 43 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); |
59607db3 SH |
44 | ns->user_ns = old_ns->user_ns; |
45 | get_user_ns(ns->user_ns); | |
efc63c4f | 46 | up_read(&uts_sem); |
071df104 SH |
47 | return ns; |
48 | } | |
49 | ||
4865ecf1 SH |
50 | /* |
51 | * Copy task tsk's utsname namespace, or clone it if flags | |
52 | * specifies CLONE_NEWUTS. In latter case, changes to the | |
53 | * utsname of this process won't be seen by parent, and vice | |
54 | * versa. | |
55 | */ | |
213dd266 | 56 | struct uts_namespace *copy_utsname(unsigned long flags, struct uts_namespace *old_ns) |
4865ecf1 | 57 | { |
071df104 | 58 | struct uts_namespace *new_ns; |
4865ecf1 | 59 | |
e3222c4e | 60 | BUG_ON(!old_ns); |
4865ecf1 SH |
61 | get_uts_ns(old_ns); |
62 | ||
071df104 | 63 | if (!(flags & CLONE_NEWUTS)) |
e3222c4e | 64 | return old_ns; |
071df104 SH |
65 | |
66 | new_ns = clone_uts_ns(old_ns); | |
071df104 | 67 | |
071df104 | 68 | put_uts_ns(old_ns); |
e3222c4e | 69 | return new_ns; |
4865ecf1 SH |
70 | } |
71 | ||
72 | void free_uts_ns(struct kref *kref) | |
73 | { | |
74 | struct uts_namespace *ns; | |
75 | ||
76 | ns = container_of(kref, struct uts_namespace, kref); | |
59607db3 | 77 | put_user_ns(ns->user_ns); |
4865ecf1 SH |
78 | kfree(ns); |
79 | } |