cregit-Linux how code gets into the kernel

Release 4.17 kernel/sysctl.c

Directory: kernel
/*
 * 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
static int proc_dopipe_max_size(struct ctl_table *table, int write,
		void __user *buffer, size_t *lenp, loff_t *ppos);

#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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Dmitry Torokhov6398.44%150.00%
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Total64100.00%2100.00%

#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 CONFIG_FW_LOADER_USER_HELPER extern struct ctl_table firmware_config_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