1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * Copyright (C) 2007 3 * Copyright (C) 2007
4 * 4 *
5 * Author: Eric Biederman <ebiederm@xmision.c 5 * Author: Eric Biederman <ebiederm@xmision.com>
6 */ 6 */
7 7
8 #include <linux/export.h> 8 #include <linux/export.h>
9 #include <linux/uts.h> 9 #include <linux/uts.h>
10 #include <linux/utsname.h> 10 #include <linux/utsname.h>
11 #include <linux/random.h> 11 #include <linux/random.h>
12 #include <linux/sysctl.h> 12 #include <linux/sysctl.h>
13 #include <linux/wait.h> 13 #include <linux/wait.h>
14 #include <linux/rwsem.h> 14 #include <linux/rwsem.h>
15 15
16 #ifdef CONFIG_PROC_SYSCTL 16 #ifdef CONFIG_PROC_SYSCTL
17 17
18 static void *get_uts(const struct ctl_table *t !! 18 static void *get_uts(struct ctl_table *table)
19 { 19 {
20 char *which = table->data; 20 char *which = table->data;
21 struct uts_namespace *uts_ns; 21 struct uts_namespace *uts_ns;
22 22
23 uts_ns = current->nsproxy->uts_ns; 23 uts_ns = current->nsproxy->uts_ns;
24 which = (which - (char *)&init_uts_ns) 24 which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
25 25
26 return which; 26 return which;
27 } 27 }
28 28
29 /* 29 /*
30 * Special case of dostring for the UTS s 30 * Special case of dostring for the UTS structure. This has locks
31 * to observe. Should this be in kernel/s 31 * to observe. Should this be in kernel/sys.c ????
32 */ 32 */
33 static int proc_do_uts_string(const struct ctl !! 33 static int proc_do_uts_string(struct ctl_table *table, int write,
34 void *buffer, size_t *lenp, 34 void *buffer, size_t *lenp, loff_t *ppos)
35 { 35 {
36 struct ctl_table uts_table; 36 struct ctl_table uts_table;
37 int r; 37 int r;
38 char tmp_data[__NEW_UTS_LEN + 1]; 38 char tmp_data[__NEW_UTS_LEN + 1];
39 39
40 memcpy(&uts_table, table, sizeof(uts_t 40 memcpy(&uts_table, table, sizeof(uts_table));
41 uts_table.data = tmp_data; 41 uts_table.data = tmp_data;
42 42
43 /* 43 /*
44 * Buffer the value in tmp_data so tha 44 * Buffer the value in tmp_data so that proc_dostring() can be called
45 * without holding any locks. 45 * without holding any locks.
46 * We also need to read the original v 46 * We also need to read the original value in the write==1 case to
47 * support partial writes. 47 * support partial writes.
48 */ 48 */
49 down_read(&uts_sem); 49 down_read(&uts_sem);
50 memcpy(tmp_data, get_uts(table), sizeo 50 memcpy(tmp_data, get_uts(table), sizeof(tmp_data));
51 up_read(&uts_sem); 51 up_read(&uts_sem);
52 r = proc_dostring(&uts_table, write, b 52 r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
53 53
54 if (write) { 54 if (write) {
55 /* 55 /*
56 * Write back the new value. 56 * Write back the new value.
57 * Note that, since we dropped 57 * Note that, since we dropped uts_sem, the result can
58 * theoretically be incorrect 58 * theoretically be incorrect if there are two parallel writes
59 * at non-zero offsets to the 59 * at non-zero offsets to the same sysctl.
60 */ 60 */
61 add_device_randomness(tmp_data 61 add_device_randomness(tmp_data, sizeof(tmp_data));
62 down_write(&uts_sem); 62 down_write(&uts_sem);
63 memcpy(get_uts(table), tmp_dat 63 memcpy(get_uts(table), tmp_data, sizeof(tmp_data));
64 up_write(&uts_sem); 64 up_write(&uts_sem);
65 proc_sys_poll_notify(table->po 65 proc_sys_poll_notify(table->poll);
66 } 66 }
67 67
68 return r; 68 return r;
69 } 69 }
70 #else 70 #else
71 #define proc_do_uts_string NULL 71 #define proc_do_uts_string NULL
72 #endif 72 #endif
73 73
74 static DEFINE_CTL_TABLE_POLL(hostname_poll); 74 static DEFINE_CTL_TABLE_POLL(hostname_poll);
75 static DEFINE_CTL_TABLE_POLL(domainname_poll); 75 static DEFINE_CTL_TABLE_POLL(domainname_poll);
76 76
77 // Note: update 'enum uts_proc' to match any c 77 // Note: update 'enum uts_proc' to match any changes to this table
78 static struct ctl_table uts_kern_table[] = { 78 static struct ctl_table uts_kern_table[] = {
79 { 79 {
80 .procname = "arch", 80 .procname = "arch",
81 .data = init_uts_ns. 81 .data = init_uts_ns.name.machine,
82 .maxlen = sizeof(init_ 82 .maxlen = sizeof(init_uts_ns.name.machine),
83 .mode = 0444, 83 .mode = 0444,
84 .proc_handler = proc_do_uts_ 84 .proc_handler = proc_do_uts_string,
85 }, 85 },
86 { 86 {
87 .procname = "ostype", 87 .procname = "ostype",
88 .data = init_uts_ns. 88 .data = init_uts_ns.name.sysname,
89 .maxlen = sizeof(init_ 89 .maxlen = sizeof(init_uts_ns.name.sysname),
90 .mode = 0444, 90 .mode = 0444,
91 .proc_handler = proc_do_uts_ 91 .proc_handler = proc_do_uts_string,
92 }, 92 },
93 { 93 {
94 .procname = "osrelease", 94 .procname = "osrelease",
95 .data = init_uts_ns. 95 .data = init_uts_ns.name.release,
96 .maxlen = sizeof(init_ 96 .maxlen = sizeof(init_uts_ns.name.release),
97 .mode = 0444, 97 .mode = 0444,
98 .proc_handler = proc_do_uts_ 98 .proc_handler = proc_do_uts_string,
99 }, 99 },
100 { 100 {
101 .procname = "version", 101 .procname = "version",
102 .data = init_uts_ns. 102 .data = init_uts_ns.name.version,
103 .maxlen = sizeof(init_ 103 .maxlen = sizeof(init_uts_ns.name.version),
104 .mode = 0444, 104 .mode = 0444,
105 .proc_handler = proc_do_uts_ 105 .proc_handler = proc_do_uts_string,
106 }, 106 },
107 { 107 {
108 .procname = "hostname", 108 .procname = "hostname",
109 .data = init_uts_ns. 109 .data = init_uts_ns.name.nodename,
110 .maxlen = sizeof(init_ 110 .maxlen = sizeof(init_uts_ns.name.nodename),
111 .mode = 0644, 111 .mode = 0644,
112 .proc_handler = proc_do_uts_ 112 .proc_handler = proc_do_uts_string,
113 .poll = &hostname_po 113 .poll = &hostname_poll,
114 }, 114 },
115 { 115 {
116 .procname = "domainname" 116 .procname = "domainname",
117 .data = init_uts_ns. 117 .data = init_uts_ns.name.domainname,
118 .maxlen = sizeof(init_ 118 .maxlen = sizeof(init_uts_ns.name.domainname),
119 .mode = 0644, 119 .mode = 0644,
120 .proc_handler = proc_do_uts_ 120 .proc_handler = proc_do_uts_string,
121 .poll = &domainname_ 121 .poll = &domainname_poll,
122 }, 122 },
>> 123 {}
>> 124 };
>> 125
>> 126 static struct ctl_table uts_root_table[] = {
>> 127 {
>> 128 .procname = "kernel",
>> 129 .mode = 0555,
>> 130 .child = uts_kern_table,
>> 131 },
>> 132 {}
123 }; 133 };
124 134
125 #ifdef CONFIG_PROC_SYSCTL 135 #ifdef CONFIG_PROC_SYSCTL
126 /* 136 /*
127 * Notify userspace about a change in a certai 137 * Notify userspace about a change in a certain entry of uts_kern_table,
128 * identified by the parameter proc. 138 * identified by the parameter proc.
129 */ 139 */
130 void uts_proc_notify(enum uts_proc proc) 140 void uts_proc_notify(enum uts_proc proc)
131 { 141 {
132 struct ctl_table *table = &uts_kern_ta 142 struct ctl_table *table = &uts_kern_table[proc];
133 143
134 proc_sys_poll_notify(table->poll); 144 proc_sys_poll_notify(table->poll);
135 } 145 }
136 #endif 146 #endif
137 147
138 static int __init utsname_sysctl_init(void) 148 static int __init utsname_sysctl_init(void)
139 { 149 {
140 register_sysctl("kernel", uts_kern_tab !! 150 register_sysctl_table(uts_root_table);
141 return 0; 151 return 0;
142 } 152 }
143 153
144 device_initcall(utsname_sysctl_init); 154 device_initcall(utsname_sysctl_init);
145 155
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