sysctl.c

linux 2.6.19 kernel source code before patching

/*
 * 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/capability.h>
#include <linux/smp_lock.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 <asm/uaccess.h>
#include <asm/processor.h>

extern int proc_nr_files(ctl_table *table, int write, struct file *filp,
                     void __user *buffer, size_t *lenp, loff_t *ppos);

#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 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;

/* 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_KMOD
extern char modprobe_path[];
#endif
#ifdef CONFIG_CHR_DEV_SG
extern 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_MATHEMU
extern int sysctl_ieee_emulation_warnings;
#endif
extern int sysctl_userprocess_debug;
extern int spin_retry;
#endif

extern int sysctl_hz_timer;

#ifdef CONFIG_BSD_PROCESS_ACCT
extern int acct_parm[];
#endif

#ifdef CONFIG_IA64
extern int no_unaligned_warning;
#endif

#ifdef CONFIG_RT_MUTEXES
extern int max_lock_depth;
#endif

#ifdef CONFIG_SYSCTL_SYSCALL
static int parse_table(int __user *, int, void __user *, size_t __user *,
		void __user *, size_t, ctl_table *);
#endif


#ifdef CONFIG_PROC_SYSCTL
static 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_PTYS
extern ctl_table pty_table[];
#endif
#ifdef CONFIG_INOTIFY_USER
extern ctl_table inotify_table[];
#endif

#ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
int sysctl_legacy_va_layout;
#endif


/* 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,
	},

	{ .ctl_name = 0 }
};

static ctl_table kern_table[] = {
	{
		.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,
	},
	{
		.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
#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,
		.procname	= "acct",
		.data		= &acct_parm,
		.maxlen		= 3*sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#ifdef CONFIG_MAGIC_SYSRQ
	{
		.ctl_name	= KERN_SYSRQ,
		.procname	= "sysrq",
		.data		= &__sysrq_enabled,
		.maxlen		= sizeof (int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#ifdef CONFIG_PROC_SYSCTL
	{
		.ctl_name	= KERN_CADPID,
		.procname	= "cad_pid",
		.data		= NULL,
		.maxlen		= sizeof (int),
		.mode		= 0600,
		.proc_handler	= &proc_do_cad_pid,
	},
#endif
	{
		.ctl_name	= KERN_MAX_THREADS,
		.procname	= "threads-max",
		.data		= &max_threads,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
	{
		.ctl_name	= KERN_RANDOM,
		.procname	= "random",
		.mode		= 0555,
		.child		= random_table,
	},
#ifdef CONFIG_UNIX98_PTYS
	{
		.ctl_name	= KERN_PTY,
		.procname	= "pty",
		.mode		= 0555,
		.child		= pty_table,
	},
#endif
	{
		.ctl_name	= KERN_OVERFLOWUID,
		.procname	= "overflowuid",
		.data		= &overflowuid,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &minolduid,
		.extra2		= &maxolduid,
	},
	{
		.ctl_name	= KERN_OVERFLOWGID,
		.procname	= "overflowgid",
		.data		= &overflowgid,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= &sysctl_intvec,
		.extra1		= &minolduid,
		.extra2		= &maxolduid,
	},
#ifdef CONFIG_S390
#ifdef CONFIG_MATHEMU
	{
		.ctl_name	= KERN_IEEE_EMULATION_WARNINGS,
		.procname	= "ieee_emulation_warnings",
		.data		= &sysctl_ieee_emulation_warnings,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#ifdef CONFIG_NO_IDLE_HZ
	{
		.ctl_name       = KERN_HZ_TIMER,
		.procname       = "hz_timer",
		.data           = &sysctl_hz_timer,
		.maxlen         = sizeof(int),
		.mode           = 0644,
		.proc_handler   = &proc_dointvec,
	},
#endif
	{
		.ctl_name	= KERN_S390_USER_DEBUG_LOGGING,
		.procname	= "userprocess_debug",
		.data		= &sysctl_userprocess_debug,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
	{
		.ctl_name	= KERN_PIDMAX,
		.procname	= "pid_max",
		.data		= &pid_max,
		.maxlen		= sizeof (int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_minmax,
		.strategy	= sysctl_intvec,
		.extra1		= &pid_max_min,
		.extra2		= &pid_max_max,
	},
	{
		.ctl_name	= KERN_PANIC_ON_OOPS,
		.procname	= "panic_on_oops",
		.data		= &panic_on_oops,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
	{
		.ctl_name	= KERN_PRINTK_RATELIMIT,
		.procname	= "printk_ratelimit",
		.data		= &printk_ratelimit_jiffies,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec_jiffies,
		.strategy	= &sysctl_jiffies,
	},
	{
		.ctl_name	= KERN_PRINTK_RATELIMIT_BURST,
		.procname	= "printk_ratelimit_burst",
		.data		= &printk_ratelimit_burst,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
	{
		.ctl_name	= KERN_NGROUPS_MAX,
		.procname	= "ngroups_max",
		.data		= &ngroups_max,
		.maxlen		= sizeof (int),
		.mode		= 0444,
		.proc_handler	= &proc_dointvec,
	},
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
	{
		.ctl_name       = KERN_UNKNOWN_NMI_PANIC,
		.procname       = "unknown_nmi_panic",
		.data           = &unknown_nmi_panic,
		.maxlen         = sizeof (int),
		.mode           = 0644,
		.proc_handler   = &proc_dointvec,
	},
	{
		.ctl_name       = KERN_NMI_WATCHDOG,
		.procname       = "nmi_watchdog",
		.data           = &nmi_watchdog_enabled,
		.maxlen         = sizeof (int),
		.mode           = 0644,
		.proc_handler   = &proc_nmi_enabled,
	},
#endif
#if defined(CONFIG_X86)
	{
		.ctl_name	= KERN_PANIC_ON_NMI,
		.procname	= "panic_on_unrecovered_nmi",
		.data		= &panic_on_unrecovered_nmi,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
	{
		.ctl_name	= KERN_BOOTLOADER_TYPE,
		.procname	= "bootloader_type",
		.data		= &bootloader_type,
		.maxlen		= sizeof (int),
		.mode		= 0444,
		.proc_handler	= &proc_dointvec,
	},
	{
		.ctl_name	= CTL_UNNUMBERED,
		.procname	= "kstack_depth_to_print",
		.data		= &kstack_depth_to_print,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#if defined(CONFIG_MMU)
	{
		.ctl_name	= KERN_RANDOMIZE,
		.procname	= "randomize_va_space",
		.data		= &randomize_va_space,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#if defined(CONFIG_S390) && defined(CONFIG_SMP)
	{
		.ctl_name	= KERN_SPIN_RETRY,
		.procname	= "spin_retry",
		.data		= &spin_retry,
		.maxlen		= sizeof (int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#ifdef CONFIG_ACPI_SLEEP
	{
		.ctl_name	= KERN_ACPI_VIDEO_FLAGS,
		.procname	= "acpi_video_flags",
		.data		= &acpi_video_flags,
		.maxlen		= sizeof (unsigned long),
		.mode		= 0644,
		.proc_handler	= &proc_doulongvec_minmax,
	},
#endif
#ifdef CONFIG_IA64
	{
		.ctl_name	= KERN_IA64_UNALIGNED,
		.procname	= "ignore-unaligned-usertrap",
		.data		= &no_unaligned_warning,
		.maxlen		= sizeof (int),
	 	.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#ifdef CONFIG_COMPAT
	{
		.ctl_name	= KERN_COMPAT_LOG,
		.procname	= "compat-log",
		.data		= &compat_log,
		.maxlen		= sizeof (int),
	 	.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
#endif
#ifdef CONFIG_RT_MUTEXES
	{