1 /*
2  * proc sysctl test driver
3  *
4  * Copyright (C) 2017 Luis R. Rodriguez <mcgrof@kernel.org>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or at your option any
9  * later version; or, when distributed separately from the Linux kernel or
10  * when incorporated into other software packages, subject to the following
11  * license:
12  *
13  * This program is free software; you can redistribute it and/or modify it
14  * under the terms of copyleft-next (version 0.3.1 or later) as published
15  * at http://copyleft-next.org/.
16  */
17 
18 /*
19  * This module provides an interface to the proc sysctl interfaces.  This
20  * driver requires CONFIG_PROC_SYSCTL. It will not normally be loaded by the
21  * system unless explicitly requested by name. You can also build this driver
22  * into your kernel.
23  */
24 
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26 
27 #include <linux/init.h>
28 #include <linux/list.h>
29 #include <linux/module.h>
30 #include <linux/printk.h>
31 #include <linux/fs.h>
32 #include <linux/miscdevice.h>
33 #include <linux/slab.h>
34 #include <linux/uaccess.h>
35 #include <linux/async.h>
36 #include <linux/delay.h>
37 #include <linux/vmalloc.h>
38 
39 static int i_zero;
40 static int i_one_hundred = 100;
41 
42 struct test_sysctl_data {
43 	int int_0001;
44 	int int_0002;
45 	int int_0003[4];
46 
47 	int boot_int;
48 
49 	unsigned int uint_0001;
50 
51 	char string_0001[65];
52 
53 #define SYSCTL_TEST_BITMAP_SIZE	65536
54 	unsigned long *bitmap_0001;
55 };
56 
57 static struct test_sysctl_data test_data = {
58 	.int_0001 = 60,
59 	.int_0002 = 1,
60 
61 	.int_0003[0] = 0,
62 	.int_0003[1] = 1,
63 	.int_0003[2] = 2,
64 	.int_0003[3] = 3,
65 
66 	.boot_int = 0,
67 
68 	.uint_0001 = 314,
69 
70 	.string_0001 = "(none)",
71 };
72 
73 /* These are all under /proc/sys/debug/test_sysctl/ */
74 static struct ctl_table test_table[] = {
75 	{
76 		.procname	= "int_0001",
77 		.data		= &test_data.int_0001,
78 		.maxlen		= sizeof(int),
79 		.mode		= 0644,
80 		.proc_handler	= proc_dointvec_minmax,
81 		.extra1		= &i_zero,
82 		.extra2         = &i_one_hundred,
83 	},
84 	{
85 		.procname	= "int_0002",
86 		.data		= &test_data.int_0002,
87 		.maxlen		= sizeof(int),
88 		.mode		= 0644,
89 		.proc_handler	= proc_dointvec,
90 	},
91 	{
92 		.procname	= "int_0003",
93 		.data		= &test_data.int_0003,
94 		.maxlen		= sizeof(test_data.int_0003),
95 		.mode		= 0644,
96 		.proc_handler	= proc_dointvec,
97 	},
98 	{
99 		.procname	= "boot_int",
100 		.data		= &test_data.boot_int,
101 		.maxlen		= sizeof(test_data.boot_int),
102 		.mode		= 0644,
103 		.proc_handler	= proc_dointvec,
104 		.extra1		= SYSCTL_ZERO,
105 		.extra2         = SYSCTL_ONE,
106 	},
107 	{
108 		.procname	= "uint_0001",
109 		.data		= &test_data.uint_0001,
110 		.maxlen		= sizeof(unsigned int),
111 		.mode		= 0644,
112 		.proc_handler	= proc_douintvec,
113 	},
114 	{
115 		.procname	= "string_0001",
116 		.data		= &test_data.string_0001,
117 		.maxlen		= sizeof(test_data.string_0001),
118 		.mode		= 0644,
119 		.proc_handler	= proc_dostring,
120 	},
121 	{
122 		.procname	= "bitmap_0001",
123 		.data		= &test_data.bitmap_0001,
124 		.maxlen		= SYSCTL_TEST_BITMAP_SIZE,
125 		.mode		= 0644,
126 		.proc_handler	= proc_do_large_bitmap,
127 	},
128 	{ }
129 };
130 
131 static struct ctl_table test_sysctl_table[] = {
132 	{
133 		.procname	= "test_sysctl",
134 		.maxlen		= 0,
135 		.mode		= 0555,
136 		.child		= test_table,
137 	},
138 	{ }
139 };
140 
141 static struct ctl_table test_sysctl_root_table[] = {
142 	{
143 		.procname	= "debug",
144 		.maxlen		= 0,
145 		.mode		= 0555,
146 		.child		= test_sysctl_table,
147 	},
148 	{ }
149 };
150 
151 static struct ctl_table_header *test_sysctl_header;
152 
test_sysctl_init(void)153 static int __init test_sysctl_init(void)
154 {
155 	test_data.bitmap_0001 = kzalloc(SYSCTL_TEST_BITMAP_SIZE/8, GFP_KERNEL);
156 	if (!test_data.bitmap_0001)
157 		return -ENOMEM;
158 	test_sysctl_header = register_sysctl_table(test_sysctl_root_table);
159 	if (!test_sysctl_header) {
160 		kfree(test_data.bitmap_0001);
161 		return -ENOMEM;
162 	}
163 	return 0;
164 }
165 module_init(test_sysctl_init);
166 
test_sysctl_exit(void)167 static void __exit test_sysctl_exit(void)
168 {
169 	kfree(test_data.bitmap_0001);
170 	if (test_sysctl_header)
171 		unregister_sysctl_table(test_sysctl_header);
172 }
173 
174 module_exit(test_sysctl_exit);
175 
176 MODULE_AUTHOR("Luis R. Rodriguez <mcgrof@kernel.org>");
177 MODULE_LICENSE("GPL");
178