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b886d83c | 1 | // SPDX-License-Identifier: GPL-2.0-only |
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2 | /* |
3 | * Copyright (C) 2007 | |
4 | * | |
5 | * Author: Eric Biederman <ebiederm@xmision.com> | |
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6 | */ |
7 | ||
9984de1a | 8 | #include <linux/export.h> |
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9 | #include <linux/uts.h> |
10 | #include <linux/utsname.h> | |
37608ba3 | 11 | #include <linux/random.h> |
39732acd | 12 | #include <linux/sysctl.h> |
f1ecf068 | 13 | #include <linux/wait.h> |
cd9c513b | 14 | #include <linux/rwsem.h> |
39732acd | 15 | |
cd89f46b YL |
16 | #ifdef CONFIG_PROC_SYSCTL |
17 | ||
42a0cc34 | 18 | static void *get_uts(struct ctl_table *table) |
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19 | { |
20 | char *which = table->data; | |
32df81cb PE |
21 | struct uts_namespace *uts_ns; |
22 | ||
23 | uts_ns = current->nsproxy->uts_ns; | |
24 | which = (which - (char *)&init_uts_ns) + (char *)uts_ns; | |
7d69a1f4 | 25 | |
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26 | return which; |
27 | } | |
28 | ||
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29 | /* |
30 | * Special case of dostring for the UTS structure. This has locks | |
31 | * to observe. Should this be in kernel/sys.c ???? | |
32 | */ | |
6f8fd1d7 | 33 | static int proc_do_uts_string(struct ctl_table *table, int write, |
32927393 | 34 | void *buffer, size_t *lenp, loff_t *ppos) |
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35 | { |
36 | struct ctl_table uts_table; | |
37 | int r; | |
42a0cc34 JH |
38 | char tmp_data[__NEW_UTS_LEN + 1]; |
39 | ||
39732acd | 40 | memcpy(&uts_table, table, sizeof(uts_table)); |
42a0cc34 JH |
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); | |
95583e4a | 52 | r = proc_dostring(&uts_table, write, buffer, lenp, ppos); |
f1ecf068 | 53 | |
42a0cc34 JH |
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 | */ | |
37608ba3 | 61 | add_device_randomness(tmp_data, sizeof(tmp_data)); |
42a0cc34 JH |
62 | down_write(&uts_sem); |
63 | memcpy(get_uts(table), tmp_data, sizeof(tmp_data)); | |
64 | up_write(&uts_sem); | |
f1ecf068 | 65 | proc_sys_poll_notify(table->poll); |
42a0cc34 | 66 | } |
f1ecf068 | 67 | |
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68 | return r; |
69 | } | |
70 | #else | |
71 | #define proc_do_uts_string NULL | |
72 | #endif | |
73 | ||
f1ecf068 LDM |
74 | static DEFINE_CTL_TABLE_POLL(hostname_poll); |
75 | static DEFINE_CTL_TABLE_POLL(domainname_poll); | |
76 | ||
39732acd | 77 | static struct ctl_table uts_kern_table[] = { |
bfca3dd3 PV |
78 | { |
79 | .procname = "arch", | |
80 | .data = init_uts_ns.name.machine, | |
81 | .maxlen = sizeof(init_uts_ns.name.machine), | |
82 | .mode = 0444, | |
83 | .proc_handler = proc_do_uts_string, | |
84 | }, | |
39732acd | 85 | { |
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86 | .procname = "ostype", |
87 | .data = init_uts_ns.name.sysname, | |
88 | .maxlen = sizeof(init_uts_ns.name.sysname), | |
89 | .mode = 0444, | |
90 | .proc_handler = proc_do_uts_string, | |
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91 | }, |
92 | { | |
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93 | .procname = "osrelease", |
94 | .data = init_uts_ns.name.release, | |
95 | .maxlen = sizeof(init_uts_ns.name.release), | |
96 | .mode = 0444, | |
97 | .proc_handler = proc_do_uts_string, | |
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98 | }, |
99 | { | |
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100 | .procname = "version", |
101 | .data = init_uts_ns.name.version, | |
102 | .maxlen = sizeof(init_uts_ns.name.version), | |
103 | .mode = 0444, | |
104 | .proc_handler = proc_do_uts_string, | |
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105 | }, |
106 | { | |
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107 | .procname = "hostname", |
108 | .data = init_uts_ns.name.nodename, | |
109 | .maxlen = sizeof(init_uts_ns.name.nodename), | |
110 | .mode = 0644, | |
111 | .proc_handler = proc_do_uts_string, | |
f1ecf068 | 112 | .poll = &hostname_poll, |
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113 | }, |
114 | { | |
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115 | .procname = "domainname", |
116 | .data = init_uts_ns.name.domainname, | |
117 | .maxlen = sizeof(init_uts_ns.name.domainname), | |
118 | .mode = 0644, | |
119 | .proc_handler = proc_do_uts_string, | |
f1ecf068 | 120 | .poll = &domainname_poll, |
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121 | }, |
122 | {} | |
123 | }; | |
124 | ||
125 | static struct ctl_table uts_root_table[] = { | |
126 | { | |
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127 | .procname = "kernel", |
128 | .mode = 0555, | |
129 | .child = uts_kern_table, | |
130 | }, | |
131 | {} | |
132 | }; | |
133 | ||
f1ecf068 LDM |
134 | #ifdef CONFIG_PROC_SYSCTL |
135 | /* | |
136 | * Notify userspace about a change in a certain entry of uts_kern_table, | |
137 | * identified by the parameter proc. | |
138 | */ | |
139 | void uts_proc_notify(enum uts_proc proc) | |
140 | { | |
141 | struct ctl_table *table = &uts_kern_table[proc]; | |
142 | ||
143 | proc_sys_poll_notify(table->poll); | |
144 | } | |
145 | #endif | |
146 | ||
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147 | static int __init utsname_sysctl_init(void) |
148 | { | |
0b4d4147 | 149 | register_sysctl_table(uts_root_table); |
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150 | return 0; |
151 | } | |
152 | ||
95583e4a | 153 | device_initcall(utsname_sysctl_init); |