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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 | #include <linux/rwsem.h> | |
18 | ||
19 | #ifdef CONFIG_PROC_SYSCTL | |
20 | ||
21 | static void *get_uts(struct ctl_table *table, int write) | |
22 | { | |
23 | char *which = table->data; | |
24 | struct uts_namespace *uts_ns; | |
25 | ||
26 | uts_ns = current->nsproxy->uts_ns; | |
27 | which = (which - (char *)&init_uts_ns) + (char *)uts_ns; | |
28 | ||
29 | if (!write) | |
30 | down_read(&uts_sem); | |
31 | else | |
32 | down_write(&uts_sem); | |
33 | return which; | |
34 | } | |
35 | ||
36 | static void put_uts(struct ctl_table *table, int write, void *which) | |
37 | { | |
38 | if (!write) | |
39 | up_read(&uts_sem); | |
40 | else | |
41 | up_write(&uts_sem); | |
42 | } | |
43 | ||
44 | /* | |
45 | * Special case of dostring for the UTS structure. This has locks | |
46 | * to observe. Should this be in kernel/sys.c ???? | |
47 | */ | |
48 | static int proc_do_uts_string(struct ctl_table *table, int write, | |
49 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
50 | { | |
51 | struct ctl_table uts_table; | |
52 | int r; | |
53 | memcpy(&uts_table, table, sizeof(uts_table)); | |
54 | uts_table.data = get_uts(table, write); | |
55 | r = proc_dostring(&uts_table, write, buffer, lenp, ppos); | |
56 | put_uts(table, write, uts_table.data); | |
57 | ||
58 | if (write) | |
59 | proc_sys_poll_notify(table->poll); | |
60 | ||
61 | return r; | |
62 | } | |
63 | #else | |
64 | #define proc_do_uts_string NULL | |
65 | #endif | |
66 | ||
67 | static DEFINE_CTL_TABLE_POLL(hostname_poll); | |
68 | static DEFINE_CTL_TABLE_POLL(domainname_poll); | |
69 | ||
70 | static struct ctl_table uts_kern_table[] = { | |
71 | { | |
72 | .procname = "ostype", | |
73 | .data = init_uts_ns.name.sysname, | |
74 | .maxlen = sizeof(init_uts_ns.name.sysname), | |
75 | .mode = 0444, | |
76 | .proc_handler = proc_do_uts_string, | |
77 | }, | |
78 | { | |
79 | .procname = "osrelease", | |
80 | .data = init_uts_ns.name.release, | |
81 | .maxlen = sizeof(init_uts_ns.name.release), | |
82 | .mode = 0444, | |
83 | .proc_handler = proc_do_uts_string, | |
84 | }, | |
85 | { | |
86 | .procname = "version", | |
87 | .data = init_uts_ns.name.version, | |
88 | .maxlen = sizeof(init_uts_ns.name.version), | |
89 | .mode = 0444, | |
90 | .proc_handler = proc_do_uts_string, | |
91 | }, | |
92 | { | |
93 | .procname = "hostname", | |
94 | .data = init_uts_ns.name.nodename, | |
95 | .maxlen = sizeof(init_uts_ns.name.nodename), | |
96 | .mode = 0644, | |
97 | .proc_handler = proc_do_uts_string, | |
98 | .poll = &hostname_poll, | |
99 | }, | |
100 | { | |
101 | .procname = "domainname", | |
102 | .data = init_uts_ns.name.domainname, | |
103 | .maxlen = sizeof(init_uts_ns.name.domainname), | |
104 | .mode = 0644, | |
105 | .proc_handler = proc_do_uts_string, | |
106 | .poll = &domainname_poll, | |
107 | }, | |
108 | {} | |
109 | }; | |
110 | ||
111 | static struct ctl_table uts_root_table[] = { | |
112 | { | |
113 | .procname = "kernel", | |
114 | .mode = 0555, | |
115 | .child = uts_kern_table, | |
116 | }, | |
117 | {} | |
118 | }; | |
119 | ||
120 | #ifdef CONFIG_PROC_SYSCTL | |
121 | /* | |
122 | * Notify userspace about a change in a certain entry of uts_kern_table, | |
123 | * identified by the parameter proc. | |
124 | */ | |
125 | void uts_proc_notify(enum uts_proc proc) | |
126 | { | |
127 | struct ctl_table *table = &uts_kern_table[proc]; | |
128 | ||
129 | proc_sys_poll_notify(table->poll); | |
130 | } | |
131 | #endif | |
132 | ||
133 | static int __init utsname_sysctl_init(void) | |
134 | { | |
135 | register_sysctl_table(uts_root_table); | |
136 | return 0; | |
137 | } | |
138 | ||
139 | device_initcall(utsname_sysctl_init); |