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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/module.h>
13#include <linux/uts.h>
14#include <linux/utsname.h>
15#include <linux/sysctl.h>
16
17static void *get_uts(ctl_table *table, int write)
18{
19 char *which = table->data;
20 struct uts_namespace *uts_ns;
21
22 uts_ns = current->nsproxy->uts_ns;
23 which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
24
25 if (!write)
26 down_read(&uts_sem);
27 else
28 down_write(&uts_sem);
29 return which;
30}
31
32static void put_uts(ctl_table *table, int write, void *which)
33{
34 if (!write)
35 up_read(&uts_sem);
36 else
37 up_write(&uts_sem);
38}
39
40#ifdef CONFIG_PROC_SYSCTL
41/*
42 * Special case of dostring for the UTS structure. This has locks
43 * to observe. Should this be in kernel/sys.c ????
44 */
45static int proc_do_uts_string(ctl_table *table, int write,
46 void __user *buffer, size_t *lenp, loff_t *ppos)
47{
48 struct ctl_table uts_table;
49 int r;
50 memcpy(&uts_table, table, sizeof(uts_table));
51 uts_table.data = get_uts(table, write);
52 r = proc_dostring(&uts_table,write,buffer,lenp, ppos);
53 put_uts(table, write, uts_table.data);
54 return r;
55}
56#else
57#define proc_do_uts_string NULL
58#endif
59
60static struct ctl_table uts_kern_table[] = {
61 {
62 .procname = "ostype",
63 .data = init_uts_ns.name.sysname,
64 .maxlen = sizeof(init_uts_ns.name.sysname),
65 .mode = 0444,
66 .proc_handler = proc_do_uts_string,
67 },
68 {
69 .procname = "osrelease",
70 .data = init_uts_ns.name.release,
71 .maxlen = sizeof(init_uts_ns.name.release),
72 .mode = 0444,
73 .proc_handler = proc_do_uts_string,
74 },
75 {
76 .procname = "version",
77 .data = init_uts_ns.name.version,
78 .maxlen = sizeof(init_uts_ns.name.version),
79 .mode = 0444,
80 .proc_handler = proc_do_uts_string,
81 },
82 {
83 .procname = "hostname",
84 .data = init_uts_ns.name.nodename,
85 .maxlen = sizeof(init_uts_ns.name.nodename),
86 .mode = 0644,
87 .proc_handler = proc_do_uts_string,
88 },
89 {
90 .procname = "domainname",
91 .data = init_uts_ns.name.domainname,
92 .maxlen = sizeof(init_uts_ns.name.domainname),
93 .mode = 0644,
94 .proc_handler = proc_do_uts_string,
95 },
96 {}
97};
98
99static struct ctl_table uts_root_table[] = {
100 {
101 .procname = "kernel",
102 .mode = 0555,
103 .child = uts_kern_table,
104 },
105 {}
106};
107
108static int __init utsname_sysctl_init(void)
109{
110 register_sysctl_table(uts_root_table);
111 return 0;
112}
113
114__initcall(utsname_sysctl_init);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2007
4 *
5 * Author: Eric Biederman <ebiederm@xmision.com>
6 */
7
8#include <linux/export.h>
9#include <linux/uts.h>
10#include <linux/utsname.h>
11#include <linux/random.h>
12#include <linux/sysctl.h>
13#include <linux/wait.h>
14#include <linux/rwsem.h>
15
16#ifdef CONFIG_PROC_SYSCTL
17
18static void *get_uts(struct ctl_table *table)
19{
20 char *which = table->data;
21 struct uts_namespace *uts_ns;
22
23 uts_ns = current->nsproxy->uts_ns;
24 which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
25
26 return which;
27}
28
29/*
30 * Special case of dostring for the UTS structure. This has locks
31 * to observe. Should this be in kernel/sys.c ????
32 */
33static int proc_do_uts_string(struct ctl_table *table, int write,
34 void *buffer, size_t *lenp, loff_t *ppos)
35{
36 struct ctl_table uts_table;
37 int r;
38 char tmp_data[__NEW_UTS_LEN + 1];
39
40 memcpy(&uts_table, table, sizeof(uts_table));
41 uts_table.data = tmp_data;
42
43 /*
44 * Buffer the value in tmp_data so that proc_dostring() can be called
45 * without holding any locks.
46 * We also need to read the original value in the write==1 case to
47 * support partial writes.
48 */
49 down_read(&uts_sem);
50 memcpy(tmp_data, get_uts(table), sizeof(tmp_data));
51 up_read(&uts_sem);
52 r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
53
54 if (write) {
55 /*
56 * Write back the new value.
57 * Note that, since we dropped uts_sem, the result can
58 * theoretically be incorrect if there are two parallel writes
59 * at non-zero offsets to the same sysctl.
60 */
61 add_device_randomness(tmp_data, sizeof(tmp_data));
62 down_write(&uts_sem);
63 memcpy(get_uts(table), tmp_data, sizeof(tmp_data));
64 up_write(&uts_sem);
65 proc_sys_poll_notify(table->poll);
66 }
67
68 return r;
69}
70#else
71#define proc_do_uts_string NULL
72#endif
73
74static DEFINE_CTL_TABLE_POLL(hostname_poll);
75static DEFINE_CTL_TABLE_POLL(domainname_poll);
76
77// Note: update 'enum uts_proc' to match any changes to this table
78static struct ctl_table uts_kern_table[] = {
79 {
80 .procname = "arch",
81 .data = init_uts_ns.name.machine,
82 .maxlen = sizeof(init_uts_ns.name.machine),
83 .mode = 0444,
84 .proc_handler = proc_do_uts_string,
85 },
86 {
87 .procname = "ostype",
88 .data = init_uts_ns.name.sysname,
89 .maxlen = sizeof(init_uts_ns.name.sysname),
90 .mode = 0444,
91 .proc_handler = proc_do_uts_string,
92 },
93 {
94 .procname = "osrelease",
95 .data = init_uts_ns.name.release,
96 .maxlen = sizeof(init_uts_ns.name.release),
97 .mode = 0444,
98 .proc_handler = proc_do_uts_string,
99 },
100 {
101 .procname = "version",
102 .data = init_uts_ns.name.version,
103 .maxlen = sizeof(init_uts_ns.name.version),
104 .mode = 0444,
105 .proc_handler = proc_do_uts_string,
106 },
107 {
108 .procname = "hostname",
109 .data = init_uts_ns.name.nodename,
110 .maxlen = sizeof(init_uts_ns.name.nodename),
111 .mode = 0644,
112 .proc_handler = proc_do_uts_string,
113 .poll = &hostname_poll,
114 },
115 {
116 .procname = "domainname",
117 .data = init_uts_ns.name.domainname,
118 .maxlen = sizeof(init_uts_ns.name.domainname),
119 .mode = 0644,
120 .proc_handler = proc_do_uts_string,
121 .poll = &domainname_poll,
122 },
123 {}
124};
125
126#ifdef CONFIG_PROC_SYSCTL
127/*
128 * Notify userspace about a change in a certain entry of uts_kern_table,
129 * identified by the parameter proc.
130 */
131void uts_proc_notify(enum uts_proc proc)
132{
133 struct ctl_table *table = &uts_kern_table[proc];
134
135 proc_sys_poll_notify(table->poll);
136}
137#endif
138
139static int __init utsname_sysctl_init(void)
140{
141 register_sysctl("kernel", uts_kern_table);
142 return 0;
143}
144
145device_initcall(utsname_sysctl_init);