kernel/printk/sysctl.c

   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
  14 static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
  15                                 void __user *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 };
  81
  82 void __init printk_sysctl_init(void)
  83 {
  84         register_sysctl_init("kernel", printk_sysctls);
  85 }