/* * 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/mm.h>#include <linux/swap.h>#include <linux/slab.h>#include <linux/sysctl.h>#include <linux/proc_fs.h>#include <linux/capability.h>#include <linux/ctype.h>#include <linux/utsname.h>#include <linux/smp_lock.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/hugetlb.h>#include <linux/security.h>#include <linux/initrd.h>#include <linux/times.h>#include <linux/limits.h>#include <linux/dcache.h>#include <linux/syscalls.h>#include <linux/nfs_fs.h>#include <linux/acpi.h>#include <linux/reboot.h> #include <asm/uaccess.h>#include <asm/processor.h> #ifdef CONFIG_X86#include <asm/nmi.h>#include <asm/stacktrace.h>#endif #if defined(CONFIG_SYSCTL) /* External variables not in a header file. */extern int C_A_D;extern int print_fatal_signals;extern int sysctl_overcommit_memory;extern int sysctl_overcommit_ratio;extern int sysctl_panic_on_oom;extern int max_threads;extern int core_uses_pid;extern int suid_dumpable;extern char core_pattern[];extern int pid_max;extern int min_free_kbytes;extern int printk_ratelimit_jiffies;extern int printk_ratelimit_burst;extern int pid_max_min, pid_max_max;extern int sysctl_drop_caches;extern int percpu_pagelist_fraction;extern int compat_log;extern int maps_protect;extern int sysctl_stat_interval;extern int audit_argv_kb; /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */static int maxolduid = 65535;static int minolduid;static int min_percpu_pagelist_fract = 8; static int ngroups_max = NGROUPS_MAX; #ifdef CONFIG_KMODextern char modprobe_path[];#endif#ifdef CONFIG_CHR_DEV_SGextern int sg_big_buff;#endif #ifdef __sparc__extern char reboot_command [];extern int stop_a_enabled;extern int scons_pwroff;#endif #ifdef __hppa__extern int pwrsw_enabled;extern int unaligned_enabled;#endif #ifdef CONFIG_S390#ifdef CONFIG_MATHEMUextern int sysctl_ieee_emulation_warnings;#endifextern int sysctl_userprocess_debug;extern int spin_retry;#endif extern int sysctl_hz_timer; #ifdef CONFIG_BSD_PROCESS_ACCTextern int acct_parm[];#endif #ifdef CONFIG_IA64extern int no_unaligned_warning;#endif #ifdef CONFIG_RT_MUTEXESextern int max_lock_depth;#endif #ifdef CONFIG_SYSCTL_SYSCALLstatic int parse_table(int __user *, int, void __user *, size_t __user *,		void __user *, size_t, ctl_table *);#endif  #ifdef CONFIG_PROC_SYSCTLstatic int proc_do_cad_pid(ctl_table *table, int write, struct file *filp,		  void __user *buffer, size_t *lenp, loff_t *ppos);static int proc_dointvec_taint(ctl_table *table, int write, struct file *filp,			       void __user *buffer, size_t *lenp, loff_t *ppos);#endif static ctl_table root_table[];static struct ctl_table_header root_table_header =	{ root_table, LIST_HEAD_INIT(root_table_header.ctl_entry) }; static ctl_table kern_table[];static ctl_table vm_table[];static ctl_table fs_table[];static ctl_table debug_table[];static ctl_table dev_table[];extern ctl_table random_table[];#ifdef CONFIG_UNIX98_PTYSextern ctl_table pty_table[];#endif#ifdef CONFIG_INOTIFY_USERextern ctl_table inotify_table[];#endif #ifdef HAVE_ARCH_PICK_MMAP_LAYOUTint sysctl_legacy_va_layout;#endif extern int prove_locking;extern int lock_stat; /* The default sysctl tables: */ static ctl_table root_table[] = {	{		.ctl_name	= CTL_KERN,		.procname	= "kernel",		.mode		= 0555,		.child		= kern_table,	},	{		.ctl_name	= CTL_VM,		.procname	= "vm",		.mode		= 0555,		.child		= vm_table,	},#ifdef CONFIG_NET	{		.ctl_name	= CTL_NET,		.procname	= "net",		.mode		= 0555,		.child		= net_table,	},#endif	{		.ctl_name	= CTL_FS,		.procname	= "fs",		.mode		= 0555,		.child		= fs_table,	},	{		.ctl_name	= CTL_DEBUG,		.procname	= "debug",		.mode		= 0555,		.child		= debug_table,	},	{		.ctl_name	= CTL_DEV,		.procname	= "dev",		.mode		= 0555,		.child		= dev_table,	},/* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt */	{ .ctl_name = 0 }}; #ifdef CONFIG_SCHED_DEBUGstatic unsigned long min_sched_granularity_ns = 100000;		/* 100 usecs */static unsigned long max_sched_granularity_ns = 1000000000;	/* 1 second */static unsigned long min_wakeup_granularity_ns;			/* 0 usecs */static unsigned long max_wakeup_granularity_ns = 1000000000;	/* 1 second */#endif static ctl_table kern_table[] = {#ifdef CONFIG_SCHED_DEBUG	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_min_granularity_ns",		.data		= &sysctl_sched_min_granularity,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_minmax,		.strategy	= &sysctl_intvec,		.extra1		= &min_sched_granularity_ns,		.extra2		= &max_sched_granularity_ns,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_latency_ns",		.data		= &sysctl_sched_latency,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_minmax,		.strategy	= &sysctl_intvec,		.extra1		= &min_sched_granularity_ns,		.extra2		= &max_sched_granularity_ns,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_wakeup_granularity_ns",		.data		= &sysctl_sched_wakeup_granularity,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_minmax,		.strategy	= &sysctl_intvec,		.extra1		= &min_wakeup_granularity_ns,		.extra2		= &max_wakeup_granularity_ns,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_batch_wakeup_granularity_ns",		.data		= &sysctl_sched_batch_wakeup_granularity,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_minmax,		.strategy	= &sysctl_intvec,		.extra1		= &min_wakeup_granularity_ns,		.extra2		= &max_wakeup_granularity_ns,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_stat_granularity_ns",		.data		= &sysctl_sched_stat_granularity,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_minmax,		.strategy	= &sysctl_intvec,		.extra1		= &min_wakeup_granularity_ns,		.extra2		= &max_wakeup_granularity_ns,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_runtime_limit_ns",		.data		= &sysctl_sched_runtime_limit,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_minmax,		.strategy	= &sysctl_intvec,		.extra1		= &min_sched_granularity_ns,		.extra2		= &max_sched_granularity_ns,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_child_runs_first",		.data		= &sysctl_sched_child_runs_first,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_features",		.data		= &sysctl_sched_features,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "sched_compat_yield",		.data		= &sysctl_sched_compat_yield,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#ifdef CONFIG_PROVE_LOCKING	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "prove_locking",		.data		= &prove_locking,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif#ifdef CONFIG_LOCK_STAT	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "lock_stat",		.data		= &lock_stat,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif	{		.ctl_name	= KERN_PANIC,		.procname	= "panic",		.data		= &panic_timeout,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},	{		.ctl_name	= KERN_CORE_USES_PID,		.procname	= "core_uses_pid",		.data		= &core_uses_pid,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#ifdef CONFIG_AUDITSYSCALL	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "audit_argv_kb",		.data		= &audit_argv_kb,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif	{		.ctl_name	= KERN_CORE_PATTERN,		.procname	= "core_pattern",		.data		= core_pattern,		.maxlen		= CORENAME_MAX_SIZE,		.mode		= 0644,		.proc_handler	= &proc_dostring,		.strategy	= &sysctl_string,	},#ifdef CONFIG_PROC_SYSCTL	{		.ctl_name	= KERN_TAINTED,		.procname	= "tainted",		.data		= &tainted,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec_taint,	},#endif	{		.ctl_name	= KERN_CAP_BSET,		.procname	= "cap-bound",		.data		= &cap_bset,		.maxlen		= sizeof(kernel_cap_t),		.mode		= 0600,		.proc_handler	= &proc_dointvec_bset,	},#ifdef CONFIG_BLK_DEV_INITRD	{		.ctl_name	= KERN_REALROOTDEV,		.procname	= "real-root-dev",		.data		= &real_root_dev,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif	{		.ctl_name	= CTL_UNNUMBERED,		.procname	= "print-fatal-signals",		.data		= &print_fatal_signals,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#ifdef __sparc__	{		.ctl_name	= KERN_SPARC_REBOOT,		.procname	= "reboot-cmd",		.data		= reboot_command,		.maxlen		= 256,		.mode		= 0644,		.proc_handler	= &proc_dostring,		.strategy	= &sysctl_string,	},	{		.ctl_name	= KERN_SPARC_STOP_A,		.procname	= "stop-a",		.data		= &stop_a_enabled,		.maxlen		= sizeof (int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},	{		.ctl_name	= KERN_SPARC_SCONS_PWROFF,		.procname	= "scons-poweroff",		.data		= &scons_pwroff,		.maxlen		= sizeof (int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif#ifdef __hppa__	{		.ctl_name	= KERN_HPPA_PWRSW,		.procname	= "soft-power",		.data		= &pwrsw_enabled,		.maxlen		= sizeof (int),	 	.mode		= 0644,		.proc_handler	= &proc_dointvec,	},	{		.ctl_name	= KERN_HPPA_UNALIGNED,		.procname	= "unaligned-trap",		.data		= &unaligned_enabled,		.maxlen		= sizeof (int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#endif	{		.ctl_name	= KERN_CTLALTDEL,		.procname	= "ctrl-alt-del",		.data		= &C_A_D,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},	{		.ctl_name	= KERN_PRINTK,		.procname	= "printk",		.data		= &console_loglevel,		.maxlen		= 4*sizeof(int),		.mode		= 0644,		.proc_handler	= &proc_dointvec,	},#ifdef CONFIG_KMOD	{		.ctl_name	= KERN_MODPROBE,		.procname	= "modprobe",		.data		= &modprobe_path,		.maxlen		= KMOD_PATH_LEN,		.mode		= 0644,		.proc_handler	= &proc_dostring,		.strategy	= &sysctl_string,	},#endif#if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)	{		.ctl_name	= KERN_HOTPLUG,		.procname	= "hotplug",		.data		= &uevent_helper,		.maxlen		= UEVENT_HELPER_PATH_LEN,		.mode		= 0644,		.proc_handler	= &proc_dostring,		.strategy	= &sysctl_string,	},#endif#ifdef CONFIG_CHR_DEV_SG	{		.ctl_name	= KERN_SG_BIG_BUFF,		.procname	= "sg-big-buff",		.data		= &sg_big_buff,		.maxlen		= sizeof (int),		.mode		= 0444,		.proc_handler	= &proc_dointvec,	},#endif#ifdef CONFIG_BSD_PROCESS_ACCT	{		.ctl_name	= KERN_ACCT,

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