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 */
clone_uts_ns(struct uts_namespace * old_ns)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 */
copy_utsname(unsigned long flags,struct uts_namespace * old_ns)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
free_uts_ns(struct kref * kref)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 }
67