[PATCH] Add SRCU-based notifier chains

[deliverable/linux.git] / kernel / sys.c

/*
 *  linux/kernel/sys.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/module.h>
#include <linux/mm.h>
#include <linux/utsname.h>
#include <linux/mman.h>
#include <linux/smp_lock.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/prctl.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/workqueue.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/key.h>
#include <linux/times.h>
#include <linux/posix-timers.h>
#include <linux/security.h>
#include <linux/dcookies.h>
#include <linux/suspend.h>
#include <linux/tty.h>
#include <linux/signal.h>
#include <linux/cn_proc.h>
#include <linux/getcpu.h>

#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/kprobes.h>

#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/unistd.h>

#ifndef SET_UNALIGN_CTL
# define SET_UNALIGN_CTL(a,b)   (-EINVAL)
#endif
#ifndef GET_UNALIGN_CTL
# define GET_UNALIGN_CTL(a,b)   (-EINVAL)
#endif
#ifndef SET_FPEMU_CTL
# define SET_FPEMU_CTL(a,b)     (-EINVAL)
#endif
#ifndef GET_FPEMU_CTL
# define GET_FPEMU_CTL(a,b)     (-EINVAL)
#endif
#ifndef SET_FPEXC_CTL
# define SET_FPEXC_CTL(a,b)     (-EINVAL)
#endif
#ifndef GET_FPEXC_CTL
# define GET_FPEXC_CTL(a,b)     (-EINVAL)
#endif
#ifndef GET_ENDIAN
# define GET_ENDIAN(a,b)        (-EINVAL)
#endif
#ifndef SET_ENDIAN
# define SET_ENDIAN(a,b)        (-EINVAL)
#endif

/*
 * this is where the system-wide overflow UID and GID are defined, for
 * architectures that now have 32-bit UID/GID but didn't in the past
 */

int overflowuid = DEFAULT_OVERFLOWUID;
int overflowgid = DEFAULT_OVERFLOWGID;

#ifdef CONFIG_UID16
EXPORT_SYMBOL(overflowuid);
EXPORT_SYMBOL(overflowgid);
#endif

/*
 * the same as above, but for filesystems which can only store a 16-bit
 * UID and GID. as such, this is needed on all architectures
 */

int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;

EXPORT_SYMBOL(fs_overflowuid);
EXPORT_SYMBOL(fs_overflowgid);

/*
 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
 */

int C_A_D = 1;
struct pid *cad_pid;
EXPORT_SYMBOL(cad_pid);

/*
 *      Notifier list for kernel code which wants to be called
 *      at shutdown. This is used to stop any idling DMA operations
 *      and the like. 
 */

static BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);

/*
 *      Notifier chain core routines.  The exported routines below
 *      are layered on top of these, with appropriate locking added.
 */

static int notifier_chain_register(struct notifier_block **nl,
                struct notifier_block *n)
{
        while ((*nl) != NULL) {
                if (n->priority > (*nl)->priority)
                        break;
                nl = &((*nl)->next);
        }
        n->next = *nl;
        rcu_assign_pointer(*nl, n);
        return 0;
}

static int notifier_chain_unregister(struct notifier_block **nl,
                struct notifier_block *n)
{
        while ((*nl) != NULL) {
                if ((*nl) == n) {
                        rcu_assign_pointer(*nl, n->next);
                        return 0;
                }
                nl = &((*nl)->next);
        }
        return -ENOENT;
}

static int __kprobes notifier_call_chain(struct notifier_block **nl,
                unsigned long val, void *v)
{
        int ret = NOTIFY_DONE;
        struct notifier_block *nb, *next_nb;

        nb = rcu_dereference(*nl);
        while (nb) {
                next_nb = rcu_dereference(nb->next);
                ret = nb->notifier_call(nb, val, v);
                if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
                        break;
                nb = next_nb;
        }
        return ret;
}

/*
 *      Atomic notifier chain routines.  Registration and unregistration
 *      use a spinlock, and call_chain is synchronized by RCU (no locks).
 */

/**
 *      atomic_notifier_chain_register - Add notifier to an atomic notifier chain
 *      @nh: Pointer to head of the atomic notifier chain
 *      @n: New entry in notifier chain
 *
 *      Adds a notifier to an atomic notifier chain.
 *
 *      Currently always returns zero.
 */

int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
                struct notifier_block *n)
{
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&nh->lock, flags);
        ret = notifier_chain_register(&nh->head, n);
        spin_unlock_irqrestore(&nh->lock, flags);
        return ret;
}

EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);

/**
 *      atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
 *      @nh: Pointer to head of the atomic notifier chain
 *      @n: Entry to remove from notifier chain
 *
 *      Removes a notifier from an atomic notifier chain.
 *
 *      Returns zero on success or %-ENOENT on failure.
 */
int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
                struct notifier_block *n)
{
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&nh->lock, flags);
        ret = notifier_chain_unregister(&nh->head, n);
        spin_unlock_irqrestore(&nh->lock, flags);
        synchronize_rcu();
        return ret;
}

EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);

/**
 *      atomic_notifier_call_chain - Call functions in an atomic notifier chain
 *      @nh: Pointer to head of the atomic notifier chain
 *      @val: Value passed unmodified to notifier function
 *      @v: Pointer passed unmodified to notifier function
 *
 *      Calls each function in a notifier chain in turn.  The functions
 *      run in an atomic context, so they must not block.
 *      This routine uses RCU to synchronize with changes to the chain.
 *
 *      If the return value of the notifier can be and'ed
 *      with %NOTIFY_STOP_MASK then atomic_notifier_call_chain
 *      will return immediately, with the return value of
 *      the notifier function which halted execution.
 *      Otherwise the return value is the return value
 *      of the last notifier function called.
 */
 
int __kprobes atomic_notifier_call_chain(struct atomic_notifier_head *nh,
                unsigned long val, void *v)
{
        int ret;

        rcu_read_lock();
        ret = notifier_call_chain(&nh->head, val, v);
        rcu_read_unlock();
        return ret;
}

EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);

/*
 *      Blocking notifier chain routines.  All access to the chain is
 *      synchronized by an rwsem.
 */

/**
 *      blocking_notifier_chain_register - Add notifier to a blocking notifier chain
 *      @nh: Pointer to head of the blocking notifier chain
 *      @n: New entry in notifier chain
 *
 *      Adds a notifier to a blocking notifier chain.
 *      Must be called in process context.
 *
 *      Currently always returns zero.
 */
 
int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
                struct notifier_block *n)
{
        int ret;

        /*
         * This code gets used during boot-up, when task switching is
         * not yet working and interrupts must remain disabled.  At
         * such times we must not call down_write().
         */
        if (unlikely(system_state == SYSTEM_BOOTING))
                return notifier_chain_register(&nh->head, n);

        down_write(&nh->rwsem);
        ret = notifier_chain_register(&nh->head, n);
        up_write(&nh->rwsem);
        return ret;
}

EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);

/**
 *      blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
 *      @nh: Pointer to head of the blocking notifier chain
 *      @n: Entry to remove from notifier chain
 *
 *      Removes a notifier from a blocking notifier chain.
 *      Must be called from process context.
 *
 *      Returns zero on success or %-ENOENT on failure.
 */
int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
                struct notifier_block *n)
{
        int ret;

        /*
         * This code gets used during boot-up, when task switching is
         * not yet working and interrupts must remain disabled.  At
         * such times we must not call down_write().
         */
        if (unlikely(system_state == SYSTEM_BOOTING))
                return notifier_chain_unregister(&nh->head, n);

        down_write(&nh->rwsem);
        ret = notifier_chain_unregister(&nh->head, n);
        up_write(&nh->rwsem);
        return ret;
}

EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);

/**
 *      blocking_notifier_call_chain - Call functions in a blocking notifier chain
 *      @nh: Pointer to head of the blocking notifier chain
 *      @val: Value passed unmodified to notifier function
 *      @v: Pointer passed unmodified to notifier function
 *
 *      Calls each function in a notifier chain in turn.  The functions
 *      run in a process context, so they are allowed to block.
 *
 *      If the return value of the notifier can be and'ed
 *      with %NOTIFY_STOP_MASK then blocking_notifier_call_chain
 *      will return immediately, with the return value of
 *      the notifier function which halted execution.
 *      Otherwise the return value is the return value
 *      of the last notifier function called.
 */
 
int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
                unsigned long val, void *v)
{
        int ret;

        down_read(&nh->rwsem);
        ret = notifier_call_chain(&nh->head, val, v);
        up_read(&nh->rwsem);
        return ret;
}

EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);

/*
 *      Raw notifier chain routines.  There is no protection;
 *      the caller must provide it.  Use at your own risk!
 */

/**
 *      raw_notifier_chain_register - Add notifier to a raw notifier chain
 *      @nh: Pointer to head of the raw notifier chain
 *      @n: New entry in notifier chain
 *
 *      Adds a notifier to a raw notifier chain.
 *      All locking must be provided by the caller.
 *
 *      Currently always returns zero.
 */

int raw_notifier_chain_register(struct raw_notifier_head *nh,
                struct notifier_block *n)
{
        return notifier_chain_register(&nh->head, n);
}

EXPORT_SYMBOL_GPL(raw_notifier_chain_register);

/**
 *      raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
 *      @nh: Pointer to head of the raw notifier chain
 *      @n: Entry to remove from notifier chain
 *
 *      Removes a notifier from a raw notifier chain.
 *      All locking must be provided by the caller.
 *
 *      Returns zero on success or %-ENOENT on failure.
 */
int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
                struct notifier_block *n)
{
        return notifier_chain_unregister(&nh->head, n);
}

EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);

/**
 *      raw_notifier_call_chain - Call functions in a raw notifier chain
 *      @nh: Pointer to head of the raw notifier chain
 *      @val: Value passed unmodified to notifier function
 *      @v: Pointer passed unmodified to notifier function
 *
 *      Calls each function in a notifier chain in turn.  The functions
 *      run in an undefined context.
 *      All locking must be provided by the caller.
 *
 *      If the return value of the notifier can be and'ed
 *      with %NOTIFY_STOP_MASK then raw_notifier_call_chain
 *      will return immediately, with the return value of
 *      the notifier function which halted execution.
 *      Otherwise the return value is the return value
 *      of the last notifier function called.
 */

int raw_notifier_call_chain(struct raw_notifier_head *nh,
                unsigned long val, void *v)
{
        return notifier_call_chain(&nh->head, val, v);
}

EXPORT_SYMBOL_GPL(raw_notifier_call_chain);

/*
 *      SRCU notifier chain routines.    Registration and unregistration
 *      use a mutex, and call_chain is synchronized by SRCU (no locks).
 */

/**
 *      srcu_notifier_chain_register - Add notifier to an SRCU notifier chain
 *      @nh: Pointer to head of the SRCU notifier chain
 *      @n: New entry in notifier chain
 *
 *      Adds a notifier to an SRCU notifier chain.
 *      Must be called in process context.
 *
 *      Currently always returns zero.
 */

int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
                struct notifier_block *n)
{
        int ret;

        /*
         * This code gets used during boot-up, when task switching is
         * not yet working and interrupts must remain disabled.  At
         * such times we must not call mutex_lock().
         */
        if (unlikely(system_state == SYSTEM_BOOTING))
                return notifier_chain_register(&nh->head, n);

        mutex_lock(&nh->mutex);
        ret = notifier_chain_register(&nh->head, n);
        mutex_unlock(&nh->mutex);
        return ret;
}

EXPORT_SYMBOL_GPL(srcu_notifier_chain_register);

/**
 *      srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain
 *      @nh: Pointer to head of the SRCU notifier chain
 *      @n: Entry to remove from notifier chain
 *
 *      Removes a notifier from an SRCU notifier chain.
 *      Must be called from process context.
 *
 *      Returns zero on success or %-ENOENT on failure.
 */
int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
                struct notifier_block *n)
{
        int ret;

        /*
         * This code gets used during boot-up, when task switching is
         * not yet working and interrupts must remain disabled.  At
         * such times we must not call mutex_lock().
         */
        if (unlikely(system_state == SYSTEM_BOOTING))
                return notifier_chain_unregister(&nh->head, n);

        mutex_lock(&nh->mutex);
        ret = notifier_chain_unregister(&nh->head, n);
        mutex_unlock(&nh->mutex);
        synchronize_srcu(&nh->srcu);
        return ret;
}

EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister);

/**
 *      srcu_notifier_call_chain - Call functions in an SRCU notifier chain
 *      @nh: Pointer to head of the SRCU notifier chain
 *      @val: Value passed unmodified to notifier function
 *      @v: Pointer passed unmodified to notifier function
 *
 *      Calls each function in a notifier chain in turn.  The functions
 *      run in a process context, so they are allowed to block.
 *
 *      If the return value of the notifier can be and'ed
 *      with %NOTIFY_STOP_MASK then srcu_notifier_call_chain
 *      will return immediately, with the return value of
 *      the notifier function which halted execution.
 *      Otherwise the return value is the return value
 *      of the last notifier function called.
 */

int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
                unsigned long val, void *v)
{
        int ret;
        int idx;

        idx = srcu_read_lock(&nh->srcu);
        ret = notifier_call_chain(&nh->head, val, v);
        srcu_read_unlock(&nh->srcu, idx);
        return ret;
}

EXPORT_SYMBOL_GPL(srcu_notifier_call_chain);

/**
 *      srcu_init_notifier_head - Initialize an SRCU notifier head
 *      @nh: Pointer to head of the srcu notifier chain
 *
 *      Unlike other sorts of notifier heads, SRCU notifier heads require
 *      dynamic initialization.  Be sure to call this routine before
 *      calling any of the other SRCU notifier routines for this head.
 *
 *      If an SRCU notifier head is deallocated, it must first be cleaned
 *      up by calling srcu_cleanup_notifier_head().  Otherwise the head's
 *      per-cpu data (used by the SRCU mechanism) will leak.
 */

void srcu_init_notifier_head(struct srcu_notifier_head *nh)
{
        mutex_init(&nh->mutex);
        init_srcu_struct(&nh->srcu);
        nh->head = NULL;
}

EXPORT_SYMBOL_GPL(srcu_init_notifier_head);

/**
 *      register_reboot_notifier - Register function to be called at reboot time
 *      @nb: Info about notifier function to be called
 *
 *      Registers a function with the list of functions
 *      to be called at reboot time.
 *
 *      Currently always returns zero, as blocking_notifier_chain_register
 *      always returns zero.
 */
 
int register_reboot_notifier(struct notifier_block * nb)
{
        return blocking_notifier_chain_register(&reboot_notifier_list, nb);
}

EXPORT_SYMBOL(register_reboot_notifier);

/**
 *      unregister_reboot_notifier - Unregister previously registered reboot notifier
 *      @nb: Hook to be unregistered
 *
 *      Unregisters a previously registered reboot
 *      notifier function.
 *
 *      Returns zero on success, or %-ENOENT on failure.
 */
 
int unregister_reboot_notifier(struct notifier_block * nb)
{
        return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
}

EXPORT_SYMBOL(unregister_reboot_notifier);

static int set_one_prio(struct task_struct *p, int niceval, int error)
{
        int no_nice;

        if (p->uid != current->euid &&
                p->euid != current->euid && !capable(CAP_SYS_NICE)) {
                error = -EPERM;
                goto out;
        }
        if (niceval < task_nice(p) && !can_nice(p, niceval)) {
                error = -EACCES;
                goto out;
        }
        no_nice = security_task_setnice(p, niceval);
        if (no_nice) {
                error = no_nice;
                goto out;
        }
        if (error == -ESRCH)
                error = 0;
        set_user_nice(p, niceval);
out:
        return error;
}

asmlinkage long sys_setpriority(int which, int who, int niceval)
{
        struct task_struct *g, *p;
        struct user_struct *user;
        int error = -EINVAL;

        if (which > 2 || which < 0)
                goto out;

        /* normalize: avoid signed division (rounding problems) */
        error = -ESRCH;
        if (niceval < -20)
                niceval = -20;
        if (niceval > 19)
                niceval = 19;

        read_lock(&tasklist_lock);
        switch (which) {
                case PRIO_PROCESS:
                        if (!who)
                                who = current->pid;
                        p = find_task_by_pid(who);
                        if (p)
                                error = set_one_prio(p, niceval, error);
                        break;
                case PRIO_PGRP:
                        if (!who)
                                who = process_group(current);
                        do_each_task_pid(who, PIDTYPE_PGID, p) {
                                error = set_one_prio(p, niceval, error);
                        } while_each_task_pid(who, PIDTYPE_PGID, p);
                        break;
                case PRIO_USER:
                        user = current->user;
                        if (!who)
                                who = current->uid;
                        else
                                if ((who != current->uid) && !(user = find_user(who)))
                                        goto out_unlock;        /* No processes for this user */

                        do_each_thread(g, p)
                                if (p->uid == who)
                                        error = set_one_prio(p, niceval, error);
                        while_each_thread(g, p);
                        if (who != current->uid)
                                free_uid(user);         /* For find_user() */
                        break;
        }
out_unlock:
        read_unlock(&tasklist_lock);
out:
        return error;
}

/*
 * Ugh. To avoid negative return values, "getpriority()" will
 * not return the normal nice-value, but a negated value that
 * has been offset by 20 (ie it returns 40..1 instead of -20..19)
 * to stay compatible.
 */
asmlinkage long sys_getpriority(int which, int who)
{
        struct task_struct *g, *p;
        struct user_struct *user;
        long niceval, retval = -ESRCH;

        if (which > 2 || which < 0)
                return -EINVAL;

        read_lock(&tasklist_lock);
        switch (which) {
                case PRIO_PROCESS:
                        if (!who)
                                who = current->pid;
                        p = find_task_by_pid(who);
                        if (p) {
                                niceval = 20 - task_nice(p);
                                if (niceval > retval)
                                        retval = niceval;
                        }
                        break;
                case PRIO_PGRP:
                        if (!who)
                                who = process_group(current);
                        do_each_task_pid(who, PIDTYPE_PGID, p) {
                                niceval = 20 - task_nice(p);
                                if (niceval > retval)
                                        retval = niceval;
                        } while_each_task_pid(who, PIDTYPE_PGID, p);
                        break;
                case PRIO_USER:
                        user = current->user;
                        if (!who)
                                who = current->uid;
                        else
                                if ((who != current->uid) && !(user = find_user(who)))
                                        goto out_unlock;        /* No processes for this user */

                        do_each_thread(g, p)
                                if (p->uid == who) {
                                        niceval = 20 - task_nice(p);
                                        if (niceval > retval)
                                                retval = niceval;
                                }
                        while_each_thread(g, p);
                        if (who != current->uid)
                                free_uid(user);         /* for find_user() */
                        break;
        }
out_unlock:
        read_unlock(&tasklist_lock);

        return retval;
}

/**
 *      emergency_restart - reboot the system
 *
 *      Without shutting down any hardware or taking any locks
 *      reboot the system.  This is called when we know we are in
 *      trouble so this is our best effort to reboot.  This is
 *      safe to call in interrupt context.
 */
void emergency_restart(void)
{
        machine_emergency_restart();
}
EXPORT_SYMBOL_GPL(emergency_restart);

static void kernel_restart_prepare(char *cmd)
{
        blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
        system_state = SYSTEM_RESTART;
        device_shutdown();
}

/**
 *      kernel_restart - reboot the system
 *      @cmd: pointer to buffer containing command to execute for restart
 *              or %NULL
 *
 *      Shutdown everything and perform a clean reboot.
 *      This is not safe to call in interrupt context.
 */
void kernel_restart(char *cmd)
{
        kernel_restart_prepare(cmd);
        if (!cmd)
                printk(KERN_EMERG "Restarting system.\n");
        else
                printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
        machine_restart(cmd);
}
EXPORT_SYMBOL_GPL(kernel_restart);

/**
 *      kernel_kexec - reboot the system
 *
 *      Move into place and start executing a preloaded standalone
 *      executable.  If nothing was preloaded return an error.
 */
static void kernel_kexec(void)
{
#ifdef CONFIG_KEXEC
        struct kimage *image;
        image = xchg(&kexec_image, NULL);
        if (!image)
                return;
        kernel_restart_prepare(NULL);
        printk(KERN_EMERG "Starting new kernel\n");
        machine_shutdown();
        machine_kexec(image);
#endif
}

void kernel_shutdown_prepare(enum system_states state)
{
        blocking_notifier_call_chain(&reboot_notifier_list,
                (state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
        system_state = state;
        device_shutdown();
}
/**
 *      kernel_halt - halt the system
 *
 *      Shutdown everything and perform a clean system halt.
 */
void kernel_halt(void)
{
        kernel_shutdown_prepare(SYSTEM_HALT);
        printk(KERN_EMERG "System halted.\n");
        machine_halt();
}

EXPORT_SYMBOL_GPL(kernel_halt);

/**
 *      kernel_power_off - power_off the system
 *
 *      Shutdown everything and perform a clean system power_off.
 */
void kernel_power_off(void)
{
        kernel_shutdown_prepare(SYSTEM_POWER_OFF);
        printk(KERN_EMERG "Power down.\n");
        machine_power_off();
}
EXPORT_SYMBOL_GPL(kernel_power_off);
/*
 * Reboot system call: for obvious reasons only root may call it,
 * and even root needs to set up some magic numbers in the registers
 * so that some mistake won't make this reboot the whole machine.
 * You can also set the meaning of the ctrl-alt-del-key here.
 *
 * reboot doesn't sync: do that yourself before calling this.
 */
asmlinkage long sys_reboot(int magic1, int magic2, unsigned int cmd, void __user * arg)
{
        char buffer[256];

        /* We only trust the superuser with rebooting the system. */
        if (!capable(CAP_SYS_BOOT))
                return -EPERM;

        /* For safety, we require "magic" arguments. */
        if (magic1 != LINUX_REBOOT_MAGIC1 ||
            (magic2 != LINUX_REBOOT_MAGIC2 &&
                        magic2 != LINUX_REBOOT_MAGIC2A &&
                        magic2 != LINUX_REBOOT_MAGIC2B &&
                        magic2 != LINUX_REBOOT_MAGIC2C))
                return -EINVAL;

        /* Instead of trying to make the power_off code look like
         * halt when pm_power_off is not set do it the easy way.
         */
        if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
                cmd = LINUX_REBOOT_CMD_HALT;

        lock_kernel();
        switch (cmd) {
        case LINUX_REBOOT_CMD_RESTART:
                kernel_restart(NULL);
                break;

        case LINUX_REBOOT_CMD_CAD_ON:
                C_A_D = 1;
                break;

        case LINUX_REBOOT_CMD_CAD_OFF:
                C_A_D = 0;
                break;

        case LINUX_REBOOT_CMD_HALT:
                kernel_halt();
                unlock_kernel();
                do_exit(0);
                break;

        case LINUX_REBOOT_CMD_POWER_OFF:
                kernel_power_off();
                unlock_kernel();
                do_exit(0);
                break;

        case LINUX_REBOOT_CMD_RESTART2:
                if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
                        unlock_kernel();
                        return -EFAULT;
                }
                buffer[sizeof(buffer) - 1] = '\0';

                kernel_restart(buffer);
                break;

        case LINUX_REBOOT_CMD_KEXEC:
                kernel_kexec();
                unlock_kernel();
                return -EINVAL;

#ifdef CONFIG_SOFTWARE_SUSPEND
        case LINUX_REBOOT_CMD_SW_SUSPEND:
                {
                        int ret = software_suspend();
                        unlock_kernel();
                        return ret;
                }
#endif

        default:
                unlock_kernel();
                return -EINVAL;
        }
        unlock_kernel();
        return 0;
}

static void deferred_cad(void *dummy)
{
        kernel_restart(NULL);
}

/*
 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
 * As it's called within an interrupt, it may NOT sync: the only choice
 * is whether to reboot at once, or just ignore the ctrl-alt-del.
 */
void ctrl_alt_del(void)
{
        static DECLARE_WORK(cad_work, deferred_cad, NULL);

        if (C_A_D)
                schedule_work(&cad_work);
        else
                kill_cad_pid(SIGINT, 1);
}
        
/*
 * Unprivileged users may change the real gid to the effective gid
 * or vice versa.  (BSD-style)
 *
 * If you set the real gid at all, or set the effective gid to a value not
 * equal to the real gid, then the saved gid is set to the new effective gid.
 *
 * This makes it possible for a setgid program to completely drop its
 * privileges, which is often a useful assertion to make when you are doing
 * a security audit over a program.
 *
 * The general idea is that a program which uses just setregid() will be
 * 100% compatible with BSD.  A program which uses just setgid() will be
 * 100% compatible with POSIX with saved IDs. 
 *
 * SMP: There are not races, the GIDs are checked only by filesystem
 *      operations (as far as semantic preservation is concerned).
 */
asmlinkage long sys_setregid(gid_t rgid, gid_t egid)
{
        int old_rgid = current->gid;
        int old_egid = current->egid;
        int new_rgid = old_rgid;
        int new_egid = old_egid;
        int retval;

        retval = security_task_setgid(rgid, egid, (gid_t)-1, LSM_SETID_RE);
        if (retval)
                return retval;

        if (rgid != (gid_t) -1) {
                if ((old_rgid == rgid) ||
                    (current->egid==rgid) ||
                    capable(CAP_SETGID))
                        new_rgid = rgid;
                else
                        return -EPERM;
        }
        if (egid != (gid_t) -1) {
                if ((old_rgid == egid) ||
                    (current->egid == egid) ||
                    (current->sgid == egid) ||
                    capable(CAP_SETGID))
                        new_egid = egid;
                else
                        return -EPERM;
        }
        if (new_egid != old_egid) {
                current->mm->dumpable = suid_dumpable;
                smp_wmb();
        }
        if (rgid != (gid_t) -1 ||
            (egid != (gid_t) -1 && egid != old_rgid))
                current->sgid = new_egid;
        current->fsgid = new_egid;
        current->egid = new_egid;
        current->gid = new_rgid;
        key_fsgid_changed(current);
        proc_id_connector(current, PROC_EVENT_GID);
        return 0;
}

/*
 * setgid() is implemented like SysV w/ SAVED_IDS 
 *
 * SMP: Same implicit races as above.
 */
asmlinkage long sys_setgid(gid_t gid)
{
        int old_egid = current->egid;
        int retval;

        retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_ID);
        if (retval)
                return retval;

        if (capable(CAP_SETGID)) {
                if (old_egid != gid) {
                        current->mm->dumpable = suid_dumpable;
                        smp_wmb();
                }
                current->gid = current->egid = current->sgid = current->fsgid = gid;
        } else if ((gid == current->gid) || (gid == current->sgid)) {
                if (old_egid != gid) {
                        current->mm->dumpable = suid_dumpable;
                        smp_wmb();
                }
                current->egid = current->fsgid = gid;
        }
        else
                return -EPERM;

        key_fsgid_changed(current);
        proc_id_connector(current, PROC_EVENT_GID);
        return 0;
}
  
static int set_user(uid_t new_ruid, int dumpclear)
{
        struct user_struct *new_user;

        new_user = alloc_uid(new_ruid);
        if (!new_user)
                return -EAGAIN;

        if (atomic_read(&new_user->processes) >=
                                current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
                        new_user != &root_user) {
                free_uid(new_user);
                return -EAGAIN;
        }

        switch_uid(new_user);

        if (dumpclear) {
                current->mm->dumpable = suid_dumpable;
                smp_wmb();
        }
        current->uid = new_ruid;
        return 0;
}

/*
 * Unprivileged users may change the real uid to the effective uid
 * or vice versa.  (BSD-style)
 *
 * If you set the real uid at all, or set the effective uid to a value not
 * equal to the real uid, then the saved uid is set to the new effective uid.
 *
 * This makes it possible for a setuid program to completely drop its
 * privileges, which is often a useful assertion to make when you are doing
 * a security audit over a program.
 *
 * The general idea is that a program which uses just setreuid() will be
 * 100% compatible with BSD.  A program which uses just setuid() will be
 * 100% compatible with POSIX with saved IDs. 
 */
asmlinkage long sys_setreuid(uid_t ruid, uid_t euid)
{
        int old_ruid, old_euid, old_suid, new_ruid, new_euid;
        int retval;

        retval = security_task_setuid(ruid, euid, (uid_t)-1, LSM_SETID_RE);
        if (retval)
                return retval;

        new_ruid = old_ruid = current->uid;
        new_euid = old_euid = current->euid;
        old_suid = current->suid;

        if (ruid != (uid_t) -1) {
                new_ruid = ruid;
                if ((old_ruid != ruid) &&
                    (current->euid != ruid) &&
                    !capable(CAP_SETUID))
                        return -EPERM;
        }

        if (euid != (uid_t) -1) {
                new_euid = euid;
                if ((old_ruid != euid) &&
                    (current->euid != euid) &&
                    (current->suid != euid) &&
                    !capable(CAP_SETUID))
                        return -EPERM;
        }

        if (new_ruid != old_ruid && set_user(new_ruid, new_euid != old_euid) < 0)
                return -EAGAIN;

        if (new_euid != old_euid) {
                current->mm->dumpable = suid_dumpable;
                smp_wmb();
        }
        current->fsuid = current->euid = new_euid;
        if (ruid != (uid_t) -1 ||
            (euid != (uid_t) -1 && euid != old_ruid))
                current->suid = current->euid;
        current->fsuid = current->euid;

        key_fsuid_changed(current);
        proc_id_connector(current, PROC_EVENT_UID);

        return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RE);
}


                
/*
 * setuid() is implemented like SysV with SAVED_IDS 
 * 
 * Note that SAVED_ID's is deficient in that a setuid root program
 * like sendmail, for example, cannot set its uid to be a normal 
 * user and then switch back, because if you're root, setuid() sets
 * the saved uid too.  If you don't like this, blame the bright people
 * in the POSIX committee and/or USG.  Note that the BSD-style setreuid()
 * will allow a root program to temporarily drop privileges and be able to
 * regain them by swapping the real and effective uid.  
 */
asmlinkage long sys_setuid(uid_t uid)
{
        int old_euid = current->euid;
        int old_ruid, old_suid, new_ruid, new_suid;
        int retval;

        retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_ID);
        if (retval)
                return retval;

        old_ruid = new_ruid = current->uid;
        old_suid = current->suid;
        new_suid = old_suid;
        
        if (capable(CAP_SETUID)) {
                if (uid != old_ruid && set_user(uid, old_euid != uid) < 0)
                        return -EAGAIN;
                new_suid = uid;
        } else if ((uid != current->uid) && (uid != new_suid))
                return -EPERM;

        if (old_euid != uid) {
                current->mm->dumpable = suid_dumpable;
                smp_wmb();
        }
        current->fsuid = current->euid = uid;
        current->suid = new_suid;

        key_fsuid_changed(current);
        proc_id_connector(current, PROC_EVENT_UID);

        return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_ID);
}


/*
 * This function implements a generic ability to update ruid, euid,
 * and suid.  This allows you to implement the 4.4 compatible seteuid().
 */
asmlinkage long sys_setresuid(uid_t ruid, uid_t euid, uid_t suid)
{
        int old_ruid = current->uid;
        int old_euid = current->euid;
        int old_suid = current->suid;
        int retval;

        retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES);
        if (retval)
                return retval;

        if (!capable(CAP_SETUID)) {
                if ((ruid != (uid_t) -1) && (ruid != current->uid) &&
                    (ruid != current->euid) && (ruid != current->suid))
                        return -EPERM;
                if ((euid != (uid_t) -1) && (euid != current->uid) &&
                    (euid != current->euid) && (euid != current->suid))
                        return -EPERM;
                if ((suid != (uid_t) -1) && (suid != current->uid) &&
                    (suid != current->euid) && (suid != current->suid))
                        return -EPERM;
        }
        if (ruid != (uid_t) -1) {
                if (ruid != current->uid && set_user(ruid, euid != current->euid) < 0)
                        return -EAGAIN;
        }
        if (euid != (uid_t) -1) {
                if (euid != current->euid) {
                        current->mm->dumpable = suid_dumpable;
                        smp_wmb();
                }
                current->euid = euid;
        }
        current->fsuid = current->euid;
        if (suid != (uid_t) -1)
                current->suid = suid;

        key_fsuid_changed(current);
        proc_id_connector(current, PROC_EVENT_UID);

        return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RES);
}

asmlinkage long sys_getresuid(uid_t __user *ruid, uid_t __user *euid, uid_t __user *suid)
{
        int retval;

        if (!(retval = put_user(current->uid, ruid)) &&
            !(retval = put_user(current->euid, euid)))
                retval = put_user(current->suid, suid);

        return retval;
}

/*
 * Same as above, but for rgid, egid, sgid.
 */
asmlinkage long sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
{
        int retval;

        retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES);
        if (retval)
                return retval;

        if (!capable(CAP_SETGID)) {
                if ((rgid != (gid_t) -1) && (rgid != current->gid) &&
                    (rgid != current->egid) && (rgid != current->sgid))
                        return -EPERM;
                if ((egid != (gid_t) -1) && (egid != current->gid) &&
                    (egid != current->egid) && (egid != current->sgid))
                        return -EPERM;
                if ((sgid != (gid_t) -1) && (sgid != current->gid) &&
                    (sgid != current->egid) && (sgid != current->sgid))
                        return -EPERM;
        }
        if (egid != (gid_t) -1) {
                if (egid != current->egid) {
                        current->mm->dumpable = suid_dumpable;
                        smp_wmb();
                }
                current->egid = egid;
        }
        current->fsgid = current->egid;
        if (rgid != (gid_t) -1)
                current->gid = rgid;
        if (sgid != (gid_t) -1)
                current->sgid = sgid;

        key_fsgid_changed(current);
        proc_id_connector(current, PROC_EVENT_GID);
        return 0;
}

asmlinkage long sys_getresgid(gid_t __user *rgid, gid_t __user *egid, gid_t __user *sgid)
{
        int retval;

        if (!(retval = put_user(current->gid, rgid)) &&
            !(retval = put_user(current->egid, egid)))
                retval = put_user(current->sgid, sgid);

        return retval;
}


/*
 * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
 * is used for "access()" and for the NFS daemon (letting nfsd stay at
 * whatever uid it wants to). It normally shadows "euid", except when
 * explicitly set by setfsuid() or for access..
 */
asmlinkage long sys_setfsuid(uid_t uid)
{
        int old_fsuid;

        old_fsuid = current->fsuid;
        if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS))
                return old_fsuid;

        if (uid == current->uid || uid == current->euid ||
            uid == current->suid || uid == current->fsuid || 
            capable(CAP_SETUID)) {
                if (uid != old_fsuid) {
                        current->mm->dumpable = suid_dumpable;
                        smp_wmb();
                }
                current->fsuid = uid;
        }

        key_fsuid_changed(current);
        proc_id_connector(current, PROC_EVENT_UID);

        security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS);

        return old_fsuid;
}

/*
 * Samma på svenska..
 */
asmlinkage long sys_setfsgid(gid_t gid)
{
        int old_fsgid;

        old_fsgid = current->fsgid;
        if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS))
                return old_fsgid;

        if (gid == current->gid || gid == current->egid ||
            gid == current->sgid || gid == current->fsgid || 
            capable(CAP_SETGID)) {
                if (gid != old_fsgid) {
                        current->mm->dumpable = suid_dumpable;
                        smp_wmb();
                }
                current->fsgid = gid;
                key_fsgid_changed(current);
                proc_id_connector(current, PROC_EVENT_GID);
        }
        return old_fsgid;
}

asmlinkage long sys_times(struct tms __user * tbuf)
{
        /*
         *      In the SMP world we might just be unlucky and have one of
         *      the times increment as we use it. Since the value is an
         *      atomically safe type this is just fine. Conceptually its
         *      as if the syscall took an instant longer to occur.
         */
        if (tbuf) {
                struct tms tmp;
                struct task_struct *tsk = current;
                struct task_struct *t;
                cputime_t utime, stime, cutime, cstime;

                spin_lock_irq(&tsk->sighand->siglock);
                utime = tsk->signal->utime;
                stime = tsk->signal->stime;
                t = tsk;
                do {
                        utime = cputime_add(utime, t->utime);
                        stime = cputime_add(stime, t->stime);
                        t = next_thread(t);
                } while (t != tsk);

                cutime = tsk->signal->cutime;
                cstime = tsk->signal->cstime;
                spin_unlock_irq(&tsk->sighand->siglock);

                tmp.tms_utime = cputime_to_clock_t(utime);
                tmp.tms_stime = cputime_to_clock_t(stime);
                tmp.tms_cutime = cputime_to_clock_t(cutime);
                tmp.tms_cstime = cputime_to_clock_t(cstime);
                if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
                        return -EFAULT;
        }
        return (long) jiffies_64_to_clock_t(get_jiffies_64());
}

/*
 * This needs some heavy checking ...
 * I just haven't the stomach for it. I also don't fully
 * understand sessions/pgrp etc. Let somebody who does explain it.
 *
 * OK, I think I have the protection semantics right.... this is really
 * only important on a multi-user system anyway, to make sure one user
 * can't send a signal to a process owned by another.  -TYT, 12/12/91
 *
 * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
 * LBT 04.03.94
 */

asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
{
        struct task_struct *p;
        struct task_struct *group_leader = current->group_leader;
        int err = -EINVAL;

        if (!pid)
                pid = group_leader->pid;
        if (!pgid)
                pgid = pid;
        if (pgid < 0)
                return -EINVAL;

        /* From this point forward we keep holding onto the tasklist lock
         * so that our parent does not change from under us. -DaveM
         */
        write_lock_irq(&tasklist_lock);

        err = -ESRCH;
        p = find_task_by_pid(pid);
        if (!p)
                goto out;

        err = -EINVAL;
        if (!thread_group_leader(p))
                goto out;

        if (p->real_parent == group_leader) {
                err = -EPERM;
                if (p->signal->session != group_leader->signal->session)
                        goto out;
                err = -EACCES;
                if (p->did_exec)
                        goto out;
        } else {
                err = -ESRCH;
                if (p != group_leader)
                        goto out;
        }

        err = -EPERM;
        if (p->signal->leader)
                goto out;

        if (pgid != pid) {
                struct task_struct *p;

                do_each_task_pid(pgid, PIDTYPE_PGID, p) {
                        if (p->signal->session == group_leader->signal->session)
                                goto ok_pgid;
                } while_each_task_pid(pgid, PIDTYPE_PGID, p);
                goto out;
        }

ok_pgid:
        err = security_task_setpgid(p, pgid);
        if (err)
                goto out;

        if (process_group(p) != pgid) {
                detach_pid(p, PIDTYPE_PGID);
                p->signal->pgrp = pgid;
                attach_pid(p, PIDTYPE_PGID, pgid);
        }

        err = 0;
out:
        /* All paths lead to here, thus we are safe. -DaveM */
        write_unlock_irq(&tasklist_lock);
        return err;
}

asmlinkage long sys_getpgid(pid_t pid)
{
        if (!pid)
                return process_group(current);
        else {
                int retval;
                struct task_struct *p;

                read_lock(&tasklist_lock);
                p = find_task_by_pid(pid);

                retval = -ESRCH;
                if (p) {
                        retval = security_task_getpgid(p);
                        if (!retval)
                                retval = process_group(p);
                }
                read_unlock(&tasklist_lock);
                return retval;
        }
}

#ifdef __ARCH_WANT_SYS_GETPGRP

asmlinkage long sys_getpgrp(void)
{
        /* SMP - assuming writes are word atomic this is fine */
        return process_group(current);
}

#endif

asmlinkage long sys_getsid(pid_t pid)
{
        if (!pid)
                return current->signal->session;
        else {
                int retval;
                struct task_struct *p;

                read_lock(&tasklist_lock);
                p = find_task_by_pid(pid);

                retval = -ESRCH;
                if (p) {
                        retval = security_task_getsid(p);
                        if (!retval)
                                retval = p->signal->session;
                }
                read_unlock(&tasklist_lock);
                return retval;
        }
}

asmlinkage long sys_setsid(void)
{
        struct task_struct *group_leader = current->group_leader;
        pid_t session;
        int err = -EPERM;

        mutex_lock(&tty_mutex);
        write_lock_irq(&tasklist_lock);

        /* Fail if I am already a session leader */
        if (group_leader->signal->leader)
                goto out;

        session = group_leader->pid;
        /* Fail if a process group id already exists that equals the
         * proposed session id.
         *
         * Don't check if session id == 1 because kernel threads use this
         * session id and so the check will always fail and make it so
         * init cannot successfully call setsid.
         */
        if (session > 1 && find_task_by_pid_type(PIDTYPE_PGID, session))
                goto out;

        group_leader->signal->leader = 1;
        __set_special_pids(session, session);
        group_leader->signal->tty = NULL;
        group_leader->signal->tty_old_pgrp = 0;
        err = process_group(group_leader);
out:
        write_unlock_irq(&tasklist_lock);
        mutex_unlock(&tty_mutex);
        return err;
}

/*
 * Supplementary group IDs
 */

/* init to 2 - one for init_task, one to ensure it is never freed */
struct group_info init_groups = { .usage = ATOMIC_INIT(2) };

struct group_info *groups_alloc(int gidsetsize)
{
        struct group_info *group_info;
        int nblocks;
        int i;

        nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
        /* Make sure we always allocate at least one indirect block pointer */
        nblocks = nblocks ? : 1;
        group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
        if (!group_info)
                return NULL;
        group_info->ngroups = gidsetsize;
        group_info->nblocks = nblocks;
        atomic_set(&group_info->usage, 1);

        if (gidsetsize <= NGROUPS_SMALL)
                group_info->blocks[0] = group_info->small_block;
        else {
                for (i = 0; i < nblocks; i++) {
                        gid_t *b;
                        b = (void *)__get_free_page(GFP_USER);
                        if (!b)
                                goto out_undo_partial_alloc;
                        group_info->blocks[i] = b;
                }
        }
        return group_info;

out_undo_partial_alloc:
        while (--i >= 0) {
                free_page((unsigned long)group_info->blocks[i]);
        }
        kfree(group_info);
        return NULL;
}

EXPORT_SYMBOL(groups_alloc);

void groups_free(struct group_info *group_info)
{
        if (group_info->blocks[0] != group_info->small_block) {
                int i;
                for (i = 0; i < group_info->nblocks; i++)
                        free_page((unsigned long)group_info->blocks[i]);
        }
        kfree(group_info);
}

EXPORT_SYMBOL(groups_free);

/* export the group_info to a user-space array */
static int groups_to_user(gid_t __user *grouplist,
    struct group_info *group_info)
{
        int i;
        int count = group_info->ngroups;

        for (i = 0; i < group_info->nblocks; i++) {
                int cp_count = min(NGROUPS_PER_BLOCK, count);
                int off = i * NGROUPS_PER_BLOCK;
                int len = cp_count * sizeof(*grouplist);

                if (copy_to_user(grouplist+off, group_info->blocks[i], len))
                        return -EFAULT;

                count -= cp_count;
        }
        return 0;
}

/* fill a group_info from a user-space array - it must be allocated already */
static int groups_from_user(struct group_info *group_info,
    gid_t __user *grouplist)
{
        int i;
        int count = group_info->ngroups;

        for (i = 0; i < group_info->nblocks; i++) {
                int cp_count = min(NGROUPS_PER_BLOCK, count);
                int off = i * NGROUPS_PER_BLOCK;
                int len = cp_count * sizeof(*grouplist);

                if (copy_from_user(group_info->blocks[i], grouplist+off, len))
                        return -EFAULT;

                count -= cp_count;
        }
        return 0;
}

/* a simple Shell sort */
static void groups_sort(struct group_info *group_info)
{
        int base, max, stride;
        int gidsetsize = group_info->ngroups;

        for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
                ; /* nothing */
        stride /= 3;

        while (stride) {
                max = gidsetsize - stride;
                for (base = 0; base < max; base++) {
                        int left = base;
                        int right = left + stride;
                        gid_t tmp = GROUP_AT(group_info, right);

                        while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
                                GROUP_AT(group_info, right) =
                                    GROUP_AT(group_info, left);
                                right = left;
                                left -= stride;
                        }
                        GROUP_AT(group_info, right) = tmp;
                }
                stride /= 3;
        }
}

/* a simple bsearch */
int groups_search(struct group_info *group_info, gid_t grp)
{
        unsigned int left, right;

        if (!group_info)
                return 0;

        left = 0;
        right = group_info->ngroups;
        while (left < right) {
                unsigned int mid = (left+right)/2;
                int cmp = grp - GROUP_AT(group_info, mid);
                if (cmp > 0)
                        left = mid + 1;
                else if (cmp < 0)
                        right = mid;
                else
                        return 1;
        }
        return 0;
}

/* validate and set current->group_info */
int set_current_groups(struct group_info *group_info)
{
        int retval;
        struct group_info *old_info;

        retval = security_task_setgroups(group_info);
        if (retval)
                return retval;

        groups_sort(group_info);
        get_group_info(group_info);

        task_lock(current);
        old_info = current->group_info;
        current->group_info = group_info;
        task_unlock(current);

        put_group_info(old_info);

        return 0;
}

EXPORT_SYMBOL(set_current_groups);

asmlinkage long sys_getgroups(int gidsetsize, gid_t __user *grouplist)
{
        int i = 0;

        /*
         *      SMP: Nobody else can change our grouplist. Thus we are
         *      safe.
         */

        if (gidsetsize < 0)
                return -EINVAL;

        /* no need to grab task_lock here; it cannot change */
        i = current->group_info->ngroups;
        if (gidsetsize) {
                if (i > gidsetsize) {
                        i = -EINVAL;
                        goto out;
                }
                if (groups_to_user(grouplist, current->group_info)) {
                        i = -EFAULT;
                        goto out;
                }
        }
out:
        return i;
}

/*
 *      SMP: Our groups are copy-on-write. We can set them safely
 *      without another task interfering.
 */
 
asmlinkage long sys_setgroups(int gidsetsize, gid_t __user *grouplist)
{
        struct group_info *group_info;
        int retval;

        if (!capable(CAP_SETGID))
                return -EPERM;
        if ((unsigned)gidsetsize > NGROUPS_MAX)
                return -EINVAL;

        group_info = groups_alloc(gidsetsize);
        if (!group_info)
                return -ENOMEM;
        retval = groups_from_user(group_info, grouplist);
        if (retval) {
                put_group_info(group_info);
                return retval;
        }

        retval = set_current_groups(group_info);
        put_group_info(group_info);

        return retval;
}

/*
 * Check whether we're fsgid/egid or in the supplemental group..
 */
int in_group_p(gid_t grp)
{
        int retval = 1;
        if (grp != current->fsgid)
                retval = groups_search(current->group_info, grp);
        return retval;
}

EXPORT_SYMBOL(in_group_p);

int in_egroup_p(gid_t grp)
{
        int retval = 1;
        if (grp != current->egid)
                retval = groups_search(current->group_info, grp);
        return retval;
}

EXPORT_SYMBOL(in_egroup_p);

DECLARE_RWSEM(uts_sem);

EXPORT_SYMBOL(uts_sem);

asmlinkage long sys_newuname(struct new_utsname __user * name)
{
        int errno = 0;

        down_read(&uts_sem);
        if (copy_to_user(name, utsname(), sizeof *name))
                errno = -EFAULT;
        up_read(&uts_sem);
        return errno;
}

asmlinkage long sys_sethostname(char __user *name, int len)
{
        int errno;
        char tmp[__NEW_UTS_LEN];

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        if (len < 0 || len > __NEW_UTS_LEN)
                return -EINVAL;
        down_write(&uts_sem);
        errno = -EFAULT;
        if (!copy_from_user(tmp, name, len)) {
                memcpy(utsname()->nodename, tmp, len);
                utsname()->nodename[len] = 0;
                errno = 0;
        }
        up_write(&uts_sem);
        return errno;
}

#ifdef __ARCH_WANT_SYS_GETHOSTNAME

asmlinkage long sys_gethostname(char __user *name, int len)
{
        int i, errno;

        if (len < 0)
                return -EINVAL;
        down_read(&uts_sem);
        i = 1 + strlen(utsname()->nodename);
        if (i > len)
                i = len;
        errno = 0;
        if (copy_to_user(name, utsname()->nodename, i))
                errno = -EFAULT;
        up_read(&uts_sem);
        return errno;
}

#endif

/*
 * Only setdomainname; getdomainname can be implemented by calling
 * uname()
 */
asmlinkage long sys_setdomainname(char __user *name, int len)
{
        int errno;
        char tmp[__NEW_UTS_LEN];

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
        if (len < 0 || len > __NEW_UTS_LEN)
                return -EINVAL;

        down_write(&uts_sem);
        errno = -EFAULT;
        if (!copy_from_user(tmp, name, len)) {
                memcpy(utsname()->domainname, tmp, len);
                utsname()->domainname[len] = 0;
                errno = 0;
        }
        up_write(&uts_sem);
        return errno;
}

asmlinkage long sys_getrlimit(unsigned int resource, struct rlimit __user *rlim)
{
        if (resource >= RLIM_NLIMITS)
                return -EINVAL;
        else {
                struct rlimit value;
                task_lock(current->group_leader);
                value = current->signal->rlim[resource];
                task_unlock(current->group_leader);
                return copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
        }
}

#ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT

/*
 *      Back compatibility for getrlimit. Needed for some apps.
 */
 
asmlinkage long sys_old_getrlimit(unsigned int resource, struct rlimit __user *rlim)
{
        struct rlimit x;
        if (resource >= RLIM_NLIMITS)
                return -EINVAL;

        task_lock(current->group_leader);
        x = current->signal->rlim[resource];
        task_unlock(current->group_leader);
        if (x.rlim_cur > 0x7FFFFFFF)
                x.rlim_cur = 0x7FFFFFFF;
        if (x.rlim_max > 0x7FFFFFFF)
                x.rlim_max = 0x7FFFFFFF;
        return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
}

#endif

asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit __user *rlim)
{
        struct rlimit new_rlim, *old_rlim;
        unsigned long it_prof_secs;
        int retval;

        if (resource >= RLIM_NLIMITS)
                return -EINVAL;
        if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
                return -EFAULT;
        if (new_rlim.rlim_cur > new_rlim.rlim_max)
                return -EINVAL;
        old_rlim = current->signal->rlim + resource;
        if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
            !capable(CAP_SYS_RESOURCE))
                return -EPERM;
        if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > NR_OPEN)
                return -EPERM;

        retval = security_task_setrlimit(resource, &new_rlim);
        if (retval)
                return retval;

        task_lock(current->group_leader);
        *old_rlim = new_rlim;
        task_unlock(current->group_leader);

        if (resource != RLIMIT_CPU)
                goto out;

        /*
         * RLIMIT_CPU handling.   Note that the kernel fails to return an error
         * code if it rejected the user's attempt to set RLIMIT_CPU.  This is a
         * very long-standing error, and fixing it now risks breakage of
         * applications, so we live with it
         */
        if (new_rlim.rlim_cur == RLIM_INFINITY)
                goto out;

        it_prof_secs = cputime_to_secs(current->signal->it_prof_expires);
        if (it_prof_secs == 0 || new_rlim.rlim_cur <= it_prof_secs) {
                unsigned long rlim_cur = new_rlim.rlim_cur;
                cputime_t cputime;

                if (rlim_cur == 0) {
                        /*
                         * The caller is asking for an immediate RLIMIT_CPU
                         * expiry.  But we use the zero value to mean "it was
                         * never set".  So let's cheat and make it one second
                         * instead
                         */
                        rlim_cur = 1;
                }
                cputime = secs_to_cputime(rlim_cur);
                read_lock(&tasklist_lock);
                spin_lock_irq(&current->sighand->siglock);
                set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
                spin_unlock_irq(&current->sighand->siglock);
                read_unlock(&tasklist_lock);
        }
out:
        return 0;
}

/*
 * It would make sense to put struct rusage in the task_struct,
 * except that would make the task_struct be *really big*.  After
 * task_struct gets moved into malloc'ed memory, it would
 * make sense to do this.  It will make moving the rest of the information
 * a lot simpler!  (Which we're not doing right now because we're not
 * measuring them yet).
 *
 * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
 * races with threads incrementing their own counters.  But since word
 * reads are atomic, we either get new values or old values and we don't
 * care which for the sums.  We always take the siglock to protect reading
 * the c* fields from p->signal from races with exit.c updating those
 * fields when reaping, so a sample either gets all the additions of a
 * given child after it's reaped, or none so this sample is before reaping.
 *
 * Locking:
 * We need to take the siglock for CHILDEREN, SELF and BOTH
 * for  the cases current multithreaded, non-current single threaded
 * non-current multithreaded.  Thread traversal is now safe with
 * the siglock held.
 * Strictly speaking, we donot need to take the siglock if we are current and
 * single threaded,  as no one else can take our signal_struct away, no one
 * else can  reap the  children to update signal->c* counters, and no one else
 * can race with the signal-> fields. If we do not take any lock, the
 * signal-> fields could be read out of order while another thread was just
 * exiting. So we should  place a read memory barrier when we avoid the lock.
 * On the writer side,  write memory barrier is implied in  __exit_signal
 * as __exit_signal releases  the siglock spinlock after updating the signal->
 * fields. But we don't do this yet to keep things simple.
 *
 */

static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
{
        struct task_struct *t;
        unsigned long flags;
        cputime_t utime, stime;

        memset((char *) r, 0, sizeof *r);
        utime = stime = cputime_zero;

        rcu_read_lock();
        if (!lock_task_sighand(p, &flags)) {
                rcu_read_unlock();
                return;
        }

        switch (who) {
                case RUSAGE_BOTH:
                case RUSAGE_CHILDREN:
                        utime = p->signal->cutime;
                        stime = p->signal->cstime;
                        r->ru_nvcsw = p->signal->cnvcsw;
                        r->ru_nivcsw = p->signal->cnivcsw;
                        r->ru_minflt = p->signal->cmin_flt;
                        r->ru_majflt = p->signal->cmaj_flt;

                        if (who == RUSAGE_CHILDREN)
                                break;

                case RUSAGE_SELF:
                        utime = cputime_add(utime, p->signal->utime);
                        stime = cputime_add(stime, p->signal->stime);
                        r->ru_nvcsw += p->signal->nvcsw;
                        r->ru_nivcsw += p->signal->nivcsw;
                        r->ru_minflt += p->signal->min_flt;
                        r->ru_majflt += p->signal->maj_flt;
                        t = p;
                        do {
                                utime = cputime_add(utime, t->utime);
                                stime = cputime_add(stime, t->stime);
                                r->ru_nvcsw += t->nvcsw;
                                r->ru_nivcsw += t->nivcsw;
                                r->ru_minflt += t->min_flt;
                                r->ru_majflt += t->maj_flt;
                                t = next_thread(t);
                        } while (t != p);
                        break;

                default:
                        BUG();
        }

        unlock_task_sighand(p, &flags);
        rcu_read_unlock();

        cputime_to_timeval(utime, &r->ru_utime);
        cputime_to_timeval(stime, &r->ru_stime);
}

int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
{
        struct rusage r;
        k_getrusage(p, who, &r);
        return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
}

asmlinkage long sys_getrusage(int who, struct rusage __user *ru)
{
        if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN)
                return -EINVAL;
        return getrusage(current, who, ru);
}

asmlinkage long sys_umask(int mask)
{
        mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
        return mask;
}
    
asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
                          unsigned long arg4, unsigned long arg5)
{
        long error;

        error = security_task_prctl(option, arg2, arg3, arg4, arg5);
        if (error)
                return error;

        switch (option) {
                case PR_SET_PDEATHSIG:
                        if (!valid_signal(arg2)) {
                                error = -EINVAL;
                                break;
                        }
                        current->pdeath_signal = arg2;
                        break;
                case PR_GET_PDEATHSIG:
                        error = put_user(current->pdeath_signal, (int __user *)arg2);
                        break;
                case PR_GET_DUMPABLE:
                        error = current->mm->dumpable;
                        break;
                case PR_SET_DUMPABLE:
                        if (arg2 < 0 || arg2 > 1) {
                                error = -EINVAL;
                                break;
                        }
                        current->mm->dumpable = arg2;
                        break;

                case PR_SET_UNALIGN:
                        error = SET_UNALIGN_CTL(current, arg2);
                        break;
                case PR_GET_UNALIGN:
                        error = GET_UNALIGN_CTL(current, arg2);
                        break;
                case PR_SET_FPEMU:
                        error = SET_FPEMU_CTL(current, arg2);
                        break;
                case PR_GET_FPEMU:
                        error = GET_FPEMU_CTL(current, arg2);
                        break;
                case PR_SET_FPEXC:
                        error = SET_FPEXC_CTL(current, arg2);
                        break;
                case PR_GET_FPEXC:
                        error = GET_FPEXC_CTL(current, arg2);
                        break;
                case PR_GET_TIMING:
                        error = PR_TIMING_STATISTICAL;
                        break;
                case PR_SET_TIMING:
                        if (arg2 == PR_TIMING_STATISTICAL)
                                error = 0;
                        else
                                error = -EINVAL;
                        break;

                case PR_GET_KEEPCAPS:
                        if (current->keep_capabilities)
                                error = 1;
                        break;
                case PR_SET_KEEPCAPS:
                        if (arg2 != 0 && arg2 != 1) {
                                error = -EINVAL;
                                break;
                        }
                        current->keep_capabilities = arg2;
                        break;
                case PR_SET_NAME: {
                        struct task_struct *me = current;
                        unsigned char ncomm[sizeof(me->comm)];

                        ncomm[sizeof(me->comm)-1] = 0;
                        if (strncpy_from_user(ncomm, (char __user *)arg2,
                                                sizeof(me->comm)-1) < 0)
                                return -EFAULT;
                        set_task_comm(me, ncomm);
                        return 0;
                }
                case PR_GET_NAME: {
                        struct task_struct *me = current;
                        unsigned char tcomm[sizeof(me->comm)];

                        get_task_comm(tcomm, me);
                        if (copy_to_user((char __user *)arg2, tcomm, sizeof(tcomm)))
                                return -EFAULT;
                        return 0;
                }
                case PR_GET_ENDIAN:
                        error = GET_ENDIAN(current, arg2);
                        break;
                case PR_SET_ENDIAN:
                        error = SET_ENDIAN(current, arg2);
                        break;

                default:
                        error = -EINVAL;
                        break;
        }
        return error;
}

asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep,
                           struct getcpu_cache __user *cache)
{
        int err = 0;
        int cpu = raw_smp_processor_id();
        if (cpup)
                err |= put_user(cpu, cpup);
        if (nodep)
                err |= put_user(cpu_to_node(cpu), nodep);
        if (cache) {
                /*
                 * The cache is not needed for this implementation,
                 * but make sure user programs pass something
                 * valid. vsyscall implementations can instead make
                 * good use of the cache. Only use t0 and t1 because
                 * these are available in both 32bit and 64bit ABI (no
                 * need for a compat_getcpu). 32bit has enough
                 * padding
                 */
                unsigned long t0, t1;
                get_user(t0, &cache->blob[0]);
                get_user(t1, &cache->blob[1]);
                t0++;
                t1++;
                put_user(t0, &cache->blob[0]);
                put_user(t1, &cache->blob[1]);
        }
        return err ? -EFAULT : 0;
}