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 *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 void __init printk_sysctl_init(void) 82 { 83 register_sysctl_init("kernel", printk_sysctls); 84 } 85