/* * 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/userfaultfd_k.h> #include "../lib/kstrtox.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_STACKLEAK_RUNTIME_DISABLE#include <linux/stackleak.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_COREDUMPextern int core_uses_pid;extern char core_pattern[];extern unsigned int core_pipe_limit;#endifextern 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_MMUextern int sysctl_nr_trim_pages;#endif /* Constants used for minimum and  maximum */#ifdef CONFIG_LOCKUP_DETECTORstatic 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 zero_ul;static unsigned long one_ul = 1;static unsigned long long_max = LONG_MAX;static int one_hundred = 100;static int one_thousand = 1000;#ifdef CONFIG_PRINTKstatic int ten_thousand = 10000;#endif#ifdef CONFIG_PERF_EVENTSstatic 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 * and hung_task_check_interval_secs */#ifdef CONFIG_DETECT_HUNG_TASKstatic 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_ALLOWextern int unaligned_enabled;#endif #ifdef CONFIG_IA64extern int unaligned_dump_stack;#endif #ifdef CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARNextern 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_PRINTKstatic 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_COREDUMPstatic int proc_dostring_coredump(struct ctl_table *table, int write,		void __user *buffer, size_t *lenp, loff_t *ppos);#endifstatic int proc_dopipe_max_size(struct ctl_table *table, int write,		void __user *buffer, size_t *lenp, loff_t *ppos);#ifdef CONFIG_BPF_SYSCALLstatic int proc_dointvec_minmax_bpf_stats(struct ctl_table *table, int write,					  void __user *buffer, size_t *lenp,					  loff_t *ppos);#endif #ifdef CONFIG_MAGIC_SYSRQ/* Note: sysrq code uses its 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;} #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_EPOLLextern struct ctl_table epoll_table[];#endif #ifdef CONFIG_FW_LOADER_USER_HELPERextern struct ctl_table firmware_config_table[];#endif #ifdef HAVE_ARCH_PICK_MMAP_LAYOUTint 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_DEBUGstatic 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_SMPstatic 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_COMPACTIONstatic 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,	},#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#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)	{		.procname	= "sched_energy_aware",		.data		= &sysctl_sched_energy_aware,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= sched_energy_aware_handler,		.extra1		= &zero,		.extra2		= &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

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