xref: /linux/kernel/printk/sysctl.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * sysctl.c: General linux system control interface
4  */
5 
6 #include <linux/sysctl.h>
7 #include <linux/printk.h>
8 #include <linux/capability.h>
9 #include <linux/ratelimit.h>
10 #include "internal.h"
11 
12 static const int ten_thousand = 10000;
13 
proc_dointvec_minmax_sysadmin(const struct ctl_table * table,int write,void * buffer,size_t * lenp,loff_t * ppos)14 static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int write,
15 				void *buffer, size_t *lenp, loff_t *ppos)
16 {
17 	if (write && !capable(CAP_SYS_ADMIN))
18 		return -EPERM;
19 
20 	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
21 }
22 
23 static struct ctl_table printk_sysctls[] = {
24 	{
25 		.procname	= "printk",
26 		.data		= &console_loglevel,
27 		.maxlen		= 4*sizeof(int),
28 		.mode		= 0644,
29 		.proc_handler	= proc_dointvec,
30 	},
31 	{
32 		.procname	= "printk_ratelimit",
33 		.data		= &printk_ratelimit_state.interval,
34 		.maxlen		= sizeof(int),
35 		.mode		= 0644,
36 		.proc_handler	= proc_dointvec_jiffies,
37 	},
38 	{
39 		.procname	= "printk_ratelimit_burst",
40 		.data		= &printk_ratelimit_state.burst,
41 		.maxlen		= sizeof(int),
42 		.mode		= 0644,
43 		.proc_handler	= proc_dointvec,
44 	},
45 	{
46 		.procname	= "printk_delay",
47 		.data		= &printk_delay_msec,
48 		.maxlen		= sizeof(int),
49 		.mode		= 0644,
50 		.proc_handler	= proc_dointvec_minmax,
51 		.extra1		= SYSCTL_ZERO,
52 		.extra2		= (void *)&ten_thousand,
53 	},
54 	{
55 		.procname	= "printk_devkmsg",
56 		.data		= devkmsg_log_str,
57 		.maxlen		= DEVKMSG_STR_MAX_SIZE,
58 		.mode		= 0644,
59 		.proc_handler	= devkmsg_sysctl_set_loglvl,
60 	},
61 	{
62 		.procname	= "dmesg_restrict",
63 		.data		= &dmesg_restrict,
64 		.maxlen		= sizeof(int),
65 		.mode		= 0644,
66 		.proc_handler	= proc_dointvec_minmax_sysadmin,
67 		.extra1		= SYSCTL_ZERO,
68 		.extra2		= SYSCTL_ONE,
69 	},
70 	{
71 		.procname	= "kptr_restrict",
72 		.data		= &kptr_restrict,
73 		.maxlen		= sizeof(int),
74 		.mode		= 0644,
75 		.proc_handler	= proc_dointvec_minmax_sysadmin,
76 		.extra1		= SYSCTL_ZERO,
77 		.extra2		= SYSCTL_TWO,
78 	},
79 };
80 
printk_sysctl_init(void)81 void __init printk_sysctl_init(void)
82 {
83 	register_sysctl_init("kernel", printk_sysctls);
84 }
85