xref: /openbmc/linux/kernel/utsname.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/version.h>
16 
17 /*
18  * Clone a new ns copying an original utsname, setting refcount to 1
19  * @old_ns: namespace to clone
20  * Return NULL on error (failure to kmalloc), new ns otherwise
21  */
22 static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
23 {
24 	struct uts_namespace *ns;
25 
26 	ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
27 	if (ns) {
28 		memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
29 		kref_init(&ns->kref);
30 	}
31 	return ns;
32 }
33 
34 /*
35  * Copy task tsk's utsname namespace, or clone it if flags
36  * specifies CLONE_NEWUTS.  In latter case, changes to the
37  * utsname of this process won't be seen by parent, and vice
38  * versa.
39  */
40 struct uts_namespace *copy_utsname(int flags, struct uts_namespace *old_ns)
41 {
42 	struct uts_namespace *new_ns;
43 
44 	BUG_ON(!old_ns);
45 	get_uts_ns(old_ns);
46 
47 	if (!(flags & CLONE_NEWUTS))
48 		return old_ns;
49 
50 	new_ns = clone_uts_ns(old_ns);
51 
52 	put_uts_ns(old_ns);
53 	return new_ns;
54 }
55 
56 void free_uts_ns(struct kref *kref)
57 {
58 	struct uts_namespace *ns;
59 
60 	ns = container_of(kref, struct uts_namespace, kref);
61 	kfree(ns);
62 }
63