1/*
2 *  Copyright (C) 2007
3 *
4 *  Author: Eric Biederman <ebiederm@xmision.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/export.h>
13#include <linux/uts.h>
14#include <linux/utsname.h>
15#include <linux/sysctl.h>
16#include <linux/wait.h>
17
18#ifdef CONFIG_PROC_SYSCTL
19
20static void *get_uts(struct ctl_table *table, int write)
21{
22	char *which = table->data;
23	struct uts_namespace *uts_ns;
24
25	uts_ns = current->nsproxy->uts_ns;
26	which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
27
28	if (!write)
29		down_read(&uts_sem);
30	else
31		down_write(&uts_sem);
32	return which;
33}
34
35static void put_uts(struct ctl_table *table, int write, void *which)
36{
37	if (!write)
38		up_read(&uts_sem);
39	else
40		up_write(&uts_sem);
41}
42
43/*
44 *	Special case of dostring for the UTS structure. This has locks
45 *	to observe. Should this be in kernel/sys.c ????
46 */
47static int proc_do_uts_string(struct ctl_table *table, int write,
48		  void __user *buffer, size_t *lenp, loff_t *ppos)
49{
50	struct ctl_table uts_table;
51	int r;
52	memcpy(&uts_table, table, sizeof(uts_table));
53	uts_table.data = get_uts(table, write);
54	r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
55	put_uts(table, write, uts_table.data);
56
57	if (write)
58		proc_sys_poll_notify(table->poll);
59
60	return r;
61}
62#else
63#define proc_do_uts_string NULL
64#endif
65
66static DEFINE_CTL_TABLE_POLL(hostname_poll);
67static DEFINE_CTL_TABLE_POLL(domainname_poll);
68
69static struct ctl_table uts_kern_table[] = {
70	{
71		.procname	= "ostype",
72		.data		= init_uts_ns.name.sysname,
73		.maxlen		= sizeof(init_uts_ns.name.sysname),
74		.mode		= 0444,
75		.proc_handler	= proc_do_uts_string,
76	},
77	{
78		.procname	= "osrelease",
79		.data		= init_uts_ns.name.release,
80		.maxlen		= sizeof(init_uts_ns.name.release),
81		.mode		= 0444,
82		.proc_handler	= proc_do_uts_string,
83	},
84	{
85		.procname	= "version",
86		.data		= init_uts_ns.name.version,
87		.maxlen		= sizeof(init_uts_ns.name.version),
88		.mode		= 0444,
89		.proc_handler	= proc_do_uts_string,
90	},
91	{
92		.procname	= "hostname",
93		.data		= init_uts_ns.name.nodename,
94		.maxlen		= sizeof(init_uts_ns.name.nodename),
95		.mode		= 0644,
96		.proc_handler	= proc_do_uts_string,
97		.poll		= &hostname_poll,
98	},
99	{
100		.procname	= "domainname",
101		.data		= init_uts_ns.name.domainname,
102		.maxlen		= sizeof(init_uts_ns.name.domainname),
103		.mode		= 0644,
104		.proc_handler	= proc_do_uts_string,
105		.poll		= &domainname_poll,
106	},
107	{}
108};
109
110static struct ctl_table uts_root_table[] = {
111	{
112		.procname	= "kernel",
113		.mode		= 0555,
114		.child		= uts_kern_table,
115	},
116	{}
117};
118
119#ifdef CONFIG_PROC_SYSCTL
120/*
121 * Notify userspace about a change in a certain entry of uts_kern_table,
122 * identified by the parameter proc.
123 */
124void uts_proc_notify(enum uts_proc proc)
125{
126	struct ctl_table *table = &uts_kern_table[proc];
127
128	proc_sys_poll_notify(table->poll);
129}
130#endif
131
132static int __init utsname_sysctl_init(void)
133{
134	register_sysctl_table(uts_root_table);
135	return 0;
136}
137
138device_initcall(utsname_sysctl_init);
139