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