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Source at commit ec7cab4cbb721bff91ec924ec691efd8daf36579 created 12 years 8 months ago. By Maarten ter Huurne, MIPS: JZ4740: A320: Updated quickstart documentation. | |
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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 | #include <linux/user_namespace.h> |
18 | |
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 | |
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 task_struct *tsk, |
35 | struct uts_namespace *old_ns) |
36 | { |
37 | struct uts_namespace *ns; |
38 | |
39 | ns = create_uts_ns(); |
40 | if (!ns) |
41 | return ERR_PTR(-ENOMEM); |
42 | |
43 | down_read(&uts_sem); |
44 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); |
45 | ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns); |
46 | up_read(&uts_sem); |
47 | return ns; |
48 | } |
49 | |
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 | */ |
56 | struct uts_namespace *copy_utsname(unsigned long flags, |
57 | struct task_struct *tsk) |
58 | { |
59 | struct uts_namespace *old_ns = tsk->nsproxy->uts_ns; |
60 | struct uts_namespace *new_ns; |
61 | |
62 | BUG_ON(!old_ns); |
63 | get_uts_ns(old_ns); |
64 | |
65 | if (!(flags & CLONE_NEWUTS)) |
66 | return old_ns; |
67 | |
68 | new_ns = clone_uts_ns(tsk, old_ns); |
69 | |
70 | put_uts_ns(old_ns); |
71 | return new_ns; |
72 | } |
73 | |
74 | void free_uts_ns(struct kref *kref) |
75 | { |
76 | struct uts_namespace *ns; |
77 | |
78 | ns = container_of(kref, struct uts_namespace, kref); |
79 | put_user_ns(ns->user_ns); |
80 | kfree(ns); |
81 | } |
82 |
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