Release 4.15 kernel/sysctl.c
/*
* sysctl.c: General linux system control interface
*
* Begun 24 March 1995, Stephen Tweedie
* Added /proc support, Dec 1995
* Added bdflush entry and intvec min/max checking, 2/23/96, Tom Dyas.
* Added hooks for /proc/sys/net (minor, minor patch), 96/4/1, Mike Shaver.
* Added kernel/java-{interpreter,appletviewer}, 96/5/10, Mike Shaver.
* Dynamic registration fixes, Stephen Tweedie.
* Added kswapd-interval, ctrl-alt-del, printk stuff, 1/8/97, Chris Horn.
* Made sysctl support optional via CONFIG_SYSCTL, 1/10/97, Chris
* Horn.
* Added proc_doulongvec_ms_jiffies_minmax, 09/08/99, Carlos H. Bauer.
* Added proc_doulongvec_minmax, 09/08/99, Carlos H. Bauer.
* Changed linked lists to use list.h instead of lists.h, 02/24/00, Bill
* Wendling.
* The list_for_each() macro wasn't appropriate for the sysctl loop.
* Removed it and replaced it with older style, 03/23/00, Bill Wendling
*/
#include <linux/module.h>
#include <linux/aio.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/bitmap.h>
#include <linux/signal.h>
#include <linux/printk.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/ctype.h>
#include <linux/kmemleak.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/net.h>
#include <linux/sysrq.h>
#include <linux/highuid.h>
#include <linux/writeback.h>
#include <linux/ratelimit.h>
#include <linux/compaction.h>
#include <linux/hugetlb.h>
#include <linux/initrd.h>
#include <linux/key.h>
#include <linux/times.h>
#include <linux/limits.h>
#include <linux/dcache.h>
#include <linux/dnotify.h>
#include <linux/syscalls.h>
#include <linux/vmstat.h>
#include <linux/nfs_fs.h>
#include <linux/acpi.h>
#include <linux/reboot.h>
#include <linux/ftrace.h>
#include <linux/perf_event.h>
#include <linux/kprobes.h>
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
#include <linux/kmod.h>
#include <linux/capability.h>
#include <linux/binfmts.h>
#include <linux/sched/sysctl.h>
#include <linux/sched/coredump.h>
#include <linux/kexec.h>
#include <linux/bpf.h>
#include <linux/mount.h>
#include <linux/pipe_fs_i.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#ifdef CONFIG_X86
#include <asm/nmi.h>
#include <asm/stacktrace.h>
#include <asm/io.h>
#endif
#ifdef CONFIG_SPARC
#include <asm/setup.h>
#endif
#ifdef CONFIG_BSD_PROCESS_ACCT
#include <linux/acct.h>
#endif
#ifdef CONFIG_RT_MUTEXES
#include <linux/rtmutex.h>
#endif
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_LOCK_STAT)
#include <linux/lockdep.h>
#endif
#ifdef CONFIG_CHR_DEV_SG
#include <scsi/sg.h>
#endif
#ifdef CONFIG_LOCKUP_DETECTOR
#include <linux/nmi.h>
#endif
#if defined(CONFIG_SYSCTL)
/* External variables not in a header file. */
extern int suid_dumpable;
#ifdef CONFIG_COREDUMP
extern int core_uses_pid;
extern char core_pattern[];
extern unsigned int core_pipe_limit;
#endif
extern int pid_max;
extern int pid_max_min, pid_max_max;
extern int percpu_pagelist_fraction;
extern int latencytop_enabled;
extern unsigned int sysctl_nr_open_min, sysctl_nr_open_max;
#ifndef CONFIG_MMU
extern int sysctl_nr_trim_pages;
#endif
/* Constants used for minimum and maximum */
#ifdef CONFIG_LOCKUP_DETECTOR
static int sixty = 60;
#endif
static int __maybe_unused neg_one = -1;
static int zero;
static int __maybe_unused one = 1;
static int __maybe_unused two = 2;
static int __maybe_unused four = 4;
static unsigned long one_ul = 1;
static int one_hundred = 100;
static int one_thousand = 1000;
#ifdef CONFIG_PRINTK
static int ten_thousand = 10000;
#endif
#ifdef CONFIG_PERF_EVENTS
static int six_hundred_forty_kb = 640 * 1024;
#endif
/* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */
static unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
static int maxolduid = 65535;
static int minolduid;
static int ngroups_max = NGROUPS_MAX;
static const int cap_last_cap = CAP_LAST_CAP;
/*this is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs */
#ifdef CONFIG_DETECT_HUNG_TASK
static unsigned long hung_task_timeout_max = (LONG_MAX/HZ);
#endif
#ifdef CONFIG_INOTIFY_USER
#include <linux/inotify.h>
#endif
#ifdef CONFIG_SPARC
#endif
#ifdef __hppa__
extern int pwrsw_enabled;
#endif
#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW
extern int unaligned_enabled;
#endif
#ifdef CONFIG_IA64
extern int unaligned_dump_stack;
#endif
#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN
extern int no_unaligned_warning;
#endif
#ifdef CONFIG_PROC_SYSCTL
/**
* enum sysctl_writes_mode - supported sysctl write modes
*
* @SYSCTL_WRITES_LEGACY: each write syscall must fully contain the sysctl value
* to be written, and multiple writes on the same sysctl file descriptor
* will rewrite the sysctl value, regardless of file position. No warning
* is issued when the initial position is not 0.
* @SYSCTL_WRITES_WARN: same as above but warn when the initial file position is
* not 0.
* @SYSCTL_WRITES_STRICT: writes to numeric sysctl entries must always be at
* file position 0 and the value must be fully contained in the buffer
* sent to the write syscall. If dealing with strings respect the file
* position, but restrict this to the max length of the buffer, anything
* passed the max lenght will be ignored. Multiple writes will append
* to the buffer.
*
* These write modes control how current file position affects the behavior of
* updating sysctl values through the proc interface on each write.
*/
enum sysctl_writes_mode {
SYSCTL_WRITES_LEGACY = -1,
SYSCTL_WRITES_WARN = 0,
SYSCTL_WRITES_STRICT = 1,
};
static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;
static int proc_do_cad_pid(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
static int proc_taint(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
#endif
#ifdef CONFIG_PRINTK
static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
#endif
static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
#ifdef CONFIG_COREDUMP
static int proc_dostring_coredump(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
/* Note: sysrq code uses it's own private copy */
static int __sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
static int sysrq_sysctl_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int error;
error = proc_dointvec(table, write, buffer, lenp, ppos);
if (error)
return error;
if (write)
sysrq_toggle_support(__sysrq_enabled);
return 0;
}
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#endif
static struct ctl_table kern_table[];
static struct ctl_table vm_table[];
static struct ctl_table fs_table[];
static struct ctl_table debug_table[];
static struct ctl_table dev_table[];
extern struct ctl_table random_table[];
#ifdef CONFIG_EPOLL
extern struct ctl_table epoll_table[];
#endif
#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
int sysctl_legacy_va_layout;
#endif
/* The default sysctl tables: */
static struct ctl_table sysctl_base_table[] = {
{
.procname = "kernel",
.mode = 0555,
.child = kern_table,
},
{
.procname = "vm",
.mode = 0555,
.child = vm_table,
},
{
.procname = "fs",
.mode = 0555,
.child = fs_table,
},
{
.procname = "debug",
.mode = 0555,
.child = debug_table,
},
{
.procname = "dev",
.mode = 0555,
.child = dev_table,
},
{ }
};
#ifdef CONFIG_SCHED_DEBUG
static int min_sched_granularity_ns = 100000;
/* 100 usecs */
static int max_sched_granularity_ns = NSEC_PER_SEC;
/* 1 second */
static int min_wakeup_granularity_ns;
/* 0 usecs */
static int max_wakeup_granularity_ns = NSEC_PER_SEC;
/* 1 second */
#ifdef CONFIG_SMP
static int min_sched_tunable_scaling = SCHED_TUNABLESCALING_NONE;
static int max_sched_tunable_scaling = SCHED_TUNABLESCALING_END-1;
#endif /* CONFIG_SMP */
#endif /* CONFIG_SCHED_DEBUG */
#ifdef CONFIG_COMPACTION
static int min_extfrag_threshold;
static int max_extfrag_threshold = 1000;
#endif
static struct ctl_table kern_table[] = {
{
.procname = "sched_child_runs_first",
.data = &sysctl_sched_child_runs_first,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#ifdef CONFIG_SCHED_DEBUG
{
.procname = "sched_min_granularity_ns",
.data = &sysctl_sched_min_granularity,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sched_proc_update_handler,
.extra1 = &min_sched_granularity_ns,
.extra2 = &max_sched_granularity_ns,
},
{
.procname = "sched_latency_ns",
.data = &sysctl_sched_latency,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sched_proc_update_handler,
.extra1 = &min_sched_granularity_ns,
.extra2 = &max_sched_granularity_ns,
},
{
.procname = "sched_wakeup_granularity_ns",
.data = &sysctl_sched_wakeup_granularity,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sched_proc_update_handler,
.extra1 = &min_wakeup_granularity_ns,
.extra2 = &max_wakeup_granularity_ns,
},
#ifdef CONFIG_SMP
{
.procname = "sched_tunable_scaling",
.data = &sysctl_sched_tunable_scaling,
.maxlen = sizeof(enum sched_tunable_scaling),
.mode = 0644,
.proc_handler = sched_proc_update_handler,
.extra1 = &min_sched_tunable_scaling,
.extra2 = &max_sched_tunable_scaling,
},
{
.procname = "sched_migration_cost_ns",
.data = &sysctl_sched_migration_cost,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "sched_nr_migrate",
.data = &sysctl_sched_nr_migrate,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "sched_time_avg_ms",
.data = &sysctl_sched_time_avg,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
},
#ifdef CONFIG_SCHEDSTATS
{
.procname = "sched_schedstats",
.data = NULL,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sysctl_schedstats,
.extra1 = &zero,
.extra2 = &one,
},
#endif /* CONFIG_SCHEDSTATS */
#endif /* CONFIG_SMP */
#ifdef CONFIG_NUMA_BALANCING
{
.procname = "numa_balancing_scan_delay_ms",
.data = &sysctl_numa_balancing_scan_delay,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "numa_balancing_scan_period_min_ms",
.data = &sysctl_numa_balancing_scan_period_min,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "numa_balancing_scan_period_max_ms",
.data = &sysctl_numa_balancing_scan_period_max,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "numa_balancing_scan_size_mb",
.data = &sysctl_numa_balancing_scan_size,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
},
{
.procname = "numa_balancing",
.data = NULL, /* filled in by handler */
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sysctl_numa_balancing,
.extra1 = &zero,
.extra2 = &one,
},
#endif /* CONFIG_NUMA_BALANCING */
#endif /* CONFIG_SCHED_DEBUG */
{
.procname = "sched_rt_period_us",
.data = &sysctl_sched_rt_period,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = sched_rt_handler,
},
{
.procname = "sched_rt_runtime_us",
.data = &sysctl_sched_rt_runtime,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rt_handler,
},
{
.procname = "sched_rr_timeslice_ms",
.data = &sysctl_sched_rr_timeslice,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sched_rr_handler,
},
#ifdef CONFIG_SCHED_AUTOGROUP
{
.procname = "sched_autogroup_enabled",
.data = &sysctl_sched_autogroup_enabled,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &one,
},
#endif
#ifdef CONFIG_CFS_BANDWIDTH
{
.procname = "sched_cfs_bandwidth_slice_us",
.data = &sysctl_sched_cfs_bandwidth_slice,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
},
#endif
#ifdef CONFIG_PROVE_LOCKING
{
.procname = "prove_locking",
.data = &prove_locking,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_LOCK_STAT
{
.procname = "lock_stat",
.data = &lock_stat,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
{
.procname = "panic",
.data = &panic_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#ifdef CONFIG_COREDUMP
{
.procname = "core_uses_pid",
.data = &core_uses_pid,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "core_pattern",
.data = core_pattern,
.maxlen = CORENAME_MAX_SIZE,
.mode = 0644,
.proc_handler = proc_dostring_coredump,
},
{
.procname = "core_pipe_limit",
.data = &core_pipe_limit,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_PROC_SYSCTL
{
.procname = "tainted",
.maxlen = sizeof(long),
.mode = 0644,
.proc_handler = proc_taint,
},
{
.procname = "sysctl_writes_strict",
.data = &sysctl_writes_strict,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &neg_one,
.extra2 = &one,
},
#endif
#ifdef CONFIG_LATENCYTOP
{
.procname = "latencytop",
.data = &latencytop_enabled,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sysctl_latencytop,
},
#endif
#ifdef CONFIG_BLK_DEV_INITRD
{
.procname = "real-root-dev",
.data = &real_root_dev,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
{
.procname = "print-fatal-signals",
.data = &print_fatal_signals,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#ifdef CONFIG_SPARC
{
.procname = "reboot-cmd",
.data = reboot_command,
.maxlen = 256,
.mode = 0644,
.proc_handler = proc_dostring,
},
{
.procname = "stop-a",
.data = &stop_a_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "scons-poweroff",
.data = &scons_pwroff,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_SPARC64
{
.procname = "tsb-ratio",
.data = &sysctl_tsb_ratio,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
#ifdef __hppa__
{
.procname = "soft-power",
.data = &pwrsw_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW
{
.procname = "unaligned-trap",
.data = &unaligned_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
{
.procname = "ctrl-alt-del",
.data = &C_A_D,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#ifdef CONFIG_FUNCTION_TRACER
{
.procname = "ftrace_enabled",
.data = &ftrace_enabled,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = ftrace_enable_sysctl,
},
#endif
#ifdef CONFIG_STACK_TRACER
{
.procname = "stack_tracer_enabled",
.data = &stack_tracer_enabled,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = stack_trace_sysctl,
},
#endif
#ifdef CONFIG_TRACING
{
.procname = "ftrace_dump_on_oops",
.data = &ftrace_dump_on_oops,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "traceoff_on_warning",
.data = &__disable_trace_on_warning,
.maxlen = sizeof(__disable_trace_on_warning),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "tracepoint_printk",
.data = &tracepoint_printk,
.maxlen = sizeof(tracepoint_printk),
.mode = 0644,
.proc_handler = tracepoint_printk_sysctl,
},
#endif
#ifdef CONFIG_KEXEC_CORE
{
.procname = "kexec_load_disabled",
.data = &kexec_load_disabled,
.maxlen = sizeof(int),
.mode = 0644,
/* only handle a transition from default "0" to "1" */
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
.extra2 = &one,
},
#endif
#ifdef CONFIG_MODULES
{
.procname = "modprobe",
.data = &modprobe_path,
.maxlen = KMOD_PATH_LEN,
.mode = 0644,
.proc_handler = proc_dostring,
},
{
.procname = "modules_disabled",
.data = &modules_disabled,
.maxlen = sizeof(int),
.mode = 0644,
/* only handle a transition from default "0" to "1" */
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
.extra2 = &one,
},
#endif
#ifdef CONFIG_UEVENT_HELPER
{
.procname = "hotplug",
.data = &uevent_helper,
.maxlen = UEVENT_HELPER_PATH_LEN,
.mode = 0644,
.proc_handler = proc_dostring,
},
#endif
#ifdef CONFIG_CHR_DEV_SG
{
.procname = "sg-big-buff",
.data = &sg_big_buff,
.maxlen = sizeof (int),
.mode = 0444,
.proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_BSD_PROCESS_ACCT
{
.procname = "acct",
.data = &acct_parm,
.maxlen = 3*sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_MAGIC_SYSRQ
{
.procname = "sysrq",
.data = &__sysrq_enabled,
.maxlen = sizeof (int),
.mode = 0644,
.proc_handler = sysrq_sysctl_handler,
},
#endif
#ifdef CONFIG_PROC_SYSCTL
{
.procname = "cad_pid",
.data = NULL,
.maxlen = sizeof (int),
.mode = 0600,
.proc_handler = proc_do_cad_pid,
},
#endif
{
.procname = "threads-max",
.data = NULL,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = sysctl_max_threads