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Eric W. Biederman39732ac2007-02-14 00:33:58 -08001/*
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
Paul Gortmaker9984de12011-05-23 14:51:41 -040012#include <linux/export.h>
Eric W. Biederman39732ac2007-02-14 00:33:58 -080013#include <linux/uts.h>
14#include <linux/utsname.h>
Eric W. Biederman39732ac2007-02-14 00:33:58 -080015#include <linux/sysctl.h>
Lucas De Marchif1ecf062011-11-02 13:39:22 -070016#include <linux/wait.h>
Eric W. Biederman39732ac2007-02-14 00:33:58 -080017
18static void *get_uts(ctl_table *table, int write)
19{
20 char *which = table->data;
Pavel Emelyanov32df81c2007-11-28 16:21:38 -080021 struct uts_namespace *uts_ns;
22
23 uts_ns = current->nsproxy->uts_ns;
24 which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
Cedric Le Goater7d69a1f2007-07-15 23:40:58 -070025
Eric W. Biederman39732ac2007-02-14 00:33:58 -080026 if (!write)
27 down_read(&uts_sem);
28 else
29 down_write(&uts_sem);
30 return which;
31}
32
33static void put_uts(ctl_table *table, int write, void *which)
34{
35 if (!write)
36 up_read(&uts_sem);
37 else
38 up_write(&uts_sem);
39}
40
Serge E. Hallyn11dea192009-04-02 16:58:27 -070041#ifdef CONFIG_PROC_SYSCTL
Eric W. Biederman39732ac2007-02-14 00:33:58 -080042/*
43 * Special case of dostring for the UTS structure. This has locks
44 * to observe. Should this be in kernel/sys.c ????
45 */
Alexey Dobriyan8d65af72009-09-23 15:57:19 -070046static int proc_do_uts_string(ctl_table *table, int write,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080047 void __user *buffer, size_t *lenp, loff_t *ppos)
48{
49 struct ctl_table uts_table;
50 int r;
51 memcpy(&uts_table, table, sizeof(uts_table));
52 uts_table.data = get_uts(table, write);
Alexey Dobriyan8d65af72009-09-23 15:57:19 -070053 r = proc_dostring(&uts_table,write,buffer,lenp, ppos);
Eric W. Biederman39732ac2007-02-14 00:33:58 -080054 put_uts(table, write, uts_table.data);
Lucas De Marchif1ecf062011-11-02 13:39:22 -070055
56 if (write)
57 proc_sys_poll_notify(table->poll);
58
Eric W. Biederman39732ac2007-02-14 00:33:58 -080059 return r;
60}
61#else
62#define proc_do_uts_string NULL
63#endif
64
Lucas De Marchif1ecf062011-11-02 13:39:22 -070065static DEFINE_CTL_TABLE_POLL(hostname_poll);
66static DEFINE_CTL_TABLE_POLL(domainname_poll);
67
Eric W. Biederman39732ac2007-02-14 00:33:58 -080068static struct ctl_table uts_kern_table[] = {
69 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080070 .procname = "ostype",
71 .data = init_uts_ns.name.sysname,
72 .maxlen = sizeof(init_uts_ns.name.sysname),
73 .mode = 0444,
74 .proc_handler = proc_do_uts_string,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080075 },
76 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080077 .procname = "osrelease",
78 .data = init_uts_ns.name.release,
79 .maxlen = sizeof(init_uts_ns.name.release),
80 .mode = 0444,
81 .proc_handler = proc_do_uts_string,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080082 },
83 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080084 .procname = "version",
85 .data = init_uts_ns.name.version,
86 .maxlen = sizeof(init_uts_ns.name.version),
87 .mode = 0444,
88 .proc_handler = proc_do_uts_string,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080089 },
90 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080091 .procname = "hostname",
92 .data = init_uts_ns.name.nodename,
93 .maxlen = sizeof(init_uts_ns.name.nodename),
94 .mode = 0644,
95 .proc_handler = proc_do_uts_string,
Lucas De Marchif1ecf062011-11-02 13:39:22 -070096 .poll = &hostname_poll,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080097 },
98 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080099 .procname = "domainname",
100 .data = init_uts_ns.name.domainname,
101 .maxlen = sizeof(init_uts_ns.name.domainname),
102 .mode = 0644,
103 .proc_handler = proc_do_uts_string,
Lucas De Marchif1ecf062011-11-02 13:39:22 -0700104 .poll = &domainname_poll,
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800105 },
106 {}
107};
108
109static struct ctl_table uts_root_table[] = {
110 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800111 .procname = "kernel",
112 .mode = 0555,
113 .child = uts_kern_table,
114 },
115 {}
116};
117
Lucas De Marchif1ecf062011-11-02 13:39:22 -0700118#ifdef CONFIG_PROC_SYSCTL
119/*
120 * Notify userspace about a change in a certain entry of uts_kern_table,
121 * identified by the parameter proc.
122 */
123void uts_proc_notify(enum uts_proc proc)
124{
125 struct ctl_table *table = &uts_kern_table[proc];
126
127 proc_sys_poll_notify(table->poll);
128}
129#endif
130
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800131static int __init utsname_sysctl_init(void)
132{
Eric W. Biederman0b4d4142007-02-14 00:34:09 -0800133 register_sysctl_table(uts_root_table);
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800134 return 0;
135}
136
137__initcall(utsname_sysctl_init);