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
get_uts(ctl_table * table,int write)20 static void *get_uts(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
put_uts(ctl_table * table,int write,void * which)35 static void put_uts(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 */
proc_do_uts_string(ctl_table * table,int write,void __user * buffer,size_t * lenp,loff_t * ppos)47 static int proc_do_uts_string(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
66 static DEFINE_CTL_TABLE_POLL(hostname_poll);
67 static DEFINE_CTL_TABLE_POLL(domainname_poll);
68
69 static 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
110 static 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 */
uts_proc_notify(enum uts_proc proc)124 void 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
utsname_sysctl_init(void)132 static int __init utsname_sysctl_init(void)
133 {
134 register_sysctl_table(uts_root_table);
135 return 0;
136 }
137
138 __initcall(utsname_sysctl_init);
139