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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
Yuanhan Liucd89f462013-02-27 17:05:22 -080018#ifdef CONFIG_PROC_SYSCTL
19
Joe Perches6f8fd1d2014-06-06 14:38:08 -070020static void *get_uts(struct ctl_table *table, int write)
Eric W. Biederman39732ac2007-02-14 00:33:58 -080021{
22 char *which = table->data;
Pavel Emelyanov32df81c2007-11-28 16:21:38 -080023 struct uts_namespace *uts_ns;
24
25 uts_ns = current->nsproxy->uts_ns;
26 which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
Cedric Le Goater7d69a1f2007-07-15 23:40:58 -070027
Eric W. Biederman39732ac2007-02-14 00:33:58 -080028 if (!write)
29 down_read(&uts_sem);
30 else
31 down_write(&uts_sem);
32 return which;
33}
34
Joe Perches6f8fd1d2014-06-06 14:38:08 -070035static void put_uts(struct ctl_table *table, int write, void *which)
Eric W. Biederman39732ac2007-02-14 00:33:58 -080036{
37 if (!write)
38 up_read(&uts_sem);
39 else
40 up_write(&uts_sem);
41}
42
Eric W. Biederman39732ac2007-02-14 00:33:58 -080043/*
44 * Special case of dostring for the UTS structure. This has locks
45 * to observe. Should this be in kernel/sys.c ????
46 */
Joe Perches6f8fd1d2014-06-06 14:38:08 -070047static int proc_do_uts_string(struct ctl_table *table, int write,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080048 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);
Fabian Frederick95583e42014-06-04 16:11:26 -070054 r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
Eric W. Biederman39732ac2007-02-14 00:33:58 -080055 put_uts(table, write, uts_table.data);
Lucas De Marchif1ecf062011-11-02 13:39:22 -070056
57 if (write)
58 proc_sys_poll_notify(table->poll);
59
Eric W. Biederman39732ac2007-02-14 00:33:58 -080060 return r;
61}
62#else
63#define proc_do_uts_string NULL
64#endif
65
Lucas De Marchif1ecf062011-11-02 13:39:22 -070066static DEFINE_CTL_TABLE_POLL(hostname_poll);
67static DEFINE_CTL_TABLE_POLL(domainname_poll);
68
Eric W. Biederman39732ac2007-02-14 00:33:58 -080069static struct ctl_table uts_kern_table[] = {
70 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080071 .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,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080076 },
77 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080078 .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,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080083 },
84 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080085 .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,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080090 },
91 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -080092 .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,
Lucas De Marchif1ecf062011-11-02 13:39:22 -070097 .poll = &hostname_poll,
Eric W. Biederman39732ac2007-02-14 00:33:58 -080098 },
99 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800100 .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,
Lucas De Marchif1ecf062011-11-02 13:39:22 -0700105 .poll = &domainname_poll,
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800106 },
107 {}
108};
109
110static struct ctl_table uts_root_table[] = {
111 {
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800112 .procname = "kernel",
113 .mode = 0555,
114 .child = uts_kern_table,
115 },
116 {}
117};
118
Lucas De Marchif1ecf062011-11-02 13:39:22 -0700119#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
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800132static int __init utsname_sysctl_init(void)
133{
Eric W. Biederman0b4d4142007-02-14 00:34:09 -0800134 register_sysctl_table(uts_root_table);
Eric W. Biederman39732ac2007-02-14 00:33:58 -0800135 return 0;
136}
137
Fabian Frederick95583e42014-06-04 16:11:26 -0700138device_initcall(utsname_sysctl_init);