sys.c

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

#include <linux/export.h>
#include <linux/mm.h>
#include <linux/utsname.h>
#include <linux/mman.h>
#include <linux/reboot.h>
#include <linux/prctl.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/kmod.h>
#include <linux/perf_event.h>
#include <linux/resource.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/task_io_accounting_ops.h>
#include <linux/seccomp.h>
#include <linux/cpu.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/fs_struct.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/gfp.h>
#include <linux/syscore_ops.h>
#include <linux/version.h>
#include <linux/ctype.h>

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

#include <linux/kmsg_dump.h>
/* Move somewhere else to avoid recompiling? */
#include <generated/utsrelease.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
#ifndef GET_TSC_CTL
# define GET_TSC_CTL(a)     (-EINVAL)
#endif
#ifndef SET_TSC_CTL
# define SET_TSC_CTL(a)     (-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;

EXPORT_SYMBOL(overflowuid);
EXPORT_SYMBOL(overflowgid);

/*
 * 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);

/*
 * If set, this is used for preparing the system to power off.
 */

void (*pm_power_off_prepare)(void);

/*
 * Returns true if current's euid is same as p's uid or euid,
 * or has CAP_SYS_NICE to p's user_ns.
 *
 * Called with rcu_read_lock, creds are safe
 */
static bool set_one_prio_perm(struct task_struct *p)
{
    const struct cred *cred = current_cred(), *pcred = __task_cred(p);

    if (uid_eq(pcred->uid,  cred->euid) ||
        uid_eq(pcred->euid, cred->euid))
        return true;
    if (ns_capable(pcred->user_ns, CAP_SYS_NICE))
        return true;
    return false;
}

/*
 * set the priority of a task
 * - the caller must hold the RCU read lock
 */
static int set_one_prio(struct task_struct *p, int niceval, int error)
{
    int no_nice;

    if (!set_one_prio_perm(p)) {
        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;
}

SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
{
    struct task_struct *g, *p;
    struct user_struct *user;
    const struct cred *cred = current_cred();
    int error = -EINVAL;
    struct pid *pgrp;
    kuid_t uid;

    if (which > PRIO_USER || which < PRIO_PROCESS)
        goto out;

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

    rcu_read_lock();
    read_lock(&tasklist_lock);
    switch (which) {
        case PRIO_PROCESS:
            if (who)
                p = find_task_by_vpid(who);
            else
                p = current;
            if (p)
                error = set_one_prio(p, niceval, error);
            break;
        case PRIO_PGRP:
            if (who)
                pgrp = find_vpid(who);
            else
                pgrp = task_pgrp(current);
            do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                error = set_one_prio(p, niceval, error);
            } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
            break;
        case PRIO_USER:
            uid = make_kuid(cred->user_ns, who);
            user = cred->user;
            if (!who)
                uid = cred->uid;
            else if (!uid_eq(uid, cred->uid) &&
                 !(user = find_user(uid)))
                goto out_unlock;    /* No processes for this user */

            do_each_thread(g, p) {
                if (uid_eq(task_uid(p), uid))
                    error = set_one_prio(p, niceval, error);
            } while_each_thread(g, p);
            if (!uid_eq(uid, cred->uid))
                free_uid(user);     /* For find_user() */
            break;
    }
out_unlock:
    read_unlock(&tasklist_lock);
    rcu_read_unlock();
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.
 */
SYSCALL_DEFINE2(getpriority, int, which, int, who)
{
    struct task_struct *g, *p;
    struct user_struct *user;
    const struct cred *cred = current_cred();
    long niceval, retval = -ESRCH;
    struct pid *pgrp;
    kuid_t uid;

    if (which > PRIO_USER || which < PRIO_PROCESS)
        return -EINVAL;

    rcu_read_lock();
    read_lock(&tasklist_lock);
    switch (which) {
        case PRIO_PROCESS:
            if (who)
                p = find_task_by_vpid(who);
            else
                p = current;
            if (p) {
                niceval = 20 - task_nice(p);
                if (niceval > retval)
                    retval = niceval;
            }
            break;
        case PRIO_PGRP:
            if (who)
                pgrp = find_vpid(who);
            else
                pgrp = task_pgrp(current);
            do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                niceval = 20 - task_nice(p);
                if (niceval > retval)
                    retval = niceval;
            } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
            break;
        case PRIO_USER:
            uid = make_kuid(cred->user_ns, who);
            user = cred->user;
            if (!who)
                uid = cred->uid;
            else if (!uid_eq(uid, cred->uid) &&
                 !(user = find_user(uid)))
                goto out_unlock;    /* No processes for this user */

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

    return retval;
}

void emergency_restart(void)
{
    kmsg_dump(KMSG_DUMP_EMERG);
    machine_emergency_restart();
}
EXPORT_SYMBOL_GPL(emergency_restart);

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

int register_reboot_notifier(struct notifier_block *nb)
{
    return blocking_notifier_chain_register(&reboot_notifier_list, nb);
}
EXPORT_SYMBOL(register_reboot_notifier);

int unregister_reboot_notifier(struct notifier_block *nb)
{
    return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
}
EXPORT_SYMBOL(unregister_reboot_notifier);

void kernel_restart(char *cmd)
{
    kernel_restart_prepare(cmd);
    disable_nonboot_cpus();
    if (!cmd)
        printk(KERN_EMERG "Restarting system.\n");
    else
        printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
    kmsg_dump(KMSG_DUMP_RESTART);
    machine_restart(cmd);
}
EXPORT_SYMBOL_GPL(kernel_restart);

static 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;
    usermodehelper_disable();
    device_shutdown();
}
void kernel_halt(void)
{
    kernel_shutdown_prepare(SYSTEM_HALT);
    syscore_shutdown();
    printk(KERN_EMERG "System halted.\n");
    kmsg_dump(KMSG_DUMP_HALT);
    machine_halt();
}

EXPORT_SYMBOL_GPL(kernel_halt);

void kernel_power_off(void)
{
    kernel_shutdown_prepare(SYSTEM_POWER_OFF);
    if (pm_power_off_prepare)
        pm_power_off_prepare();
    disable_nonboot_cpus();
    syscore_shutdown();
    printk(KERN_EMERG "Power down.\n");
    kmsg_dump(KMSG_DUMP_POWEROFF);
    machine_power_off();
}
EXPORT_SYMBOL_GPL(kernel_power_off);

static DEFINE_MUTEX(reboot_mutex);

/*
 * 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.
 */
SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
        void __user *, arg)
{
    char buffer[256];
    int ret = 0;

    /* 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;

    /*
     * If pid namespaces are enabled and the current task is in a child
     * pid_namespace, the command is handled by reboot_pid_ns() which will
     * call do_exit().
     */
    ret = reboot_pid_ns(task_active_pid_ns(current), cmd);
    if (ret)
        return ret;

    /* 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;

    mutex_lock(&reboot_mutex);
    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();
        do_exit(0);
        panic("cannot halt");

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

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

        kernel_restart(buffer);
        break;

#ifdef CONFIG_KEXEC
    case LINUX_REBOOT_CMD_KEXEC:
        ret = kernel_kexec();
        break;
#endif

#ifdef CONFIG_HIBERNATION
    case LINUX_REBOOT_CMD_SW_SUSPEND:
        ret = hibernate();
        break;
#endif

    default:
        ret = -EINVAL;
        break;
    }
    mutex_unlock(&reboot_mutex);
    return ret;
}

static void deferred_cad(struct work_struct *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);

    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).
 */
SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
{
    struct user_namespace *ns = current_user_ns();
    const struct cred *old;
    struct cred *new;
    int retval;
    kgid_t krgid, kegid;

    krgid = make_kgid(ns, rgid);
    kegid = make_kgid(ns, egid);

    if ((rgid != (gid_t) -1) && !gid_valid(krgid))
        return -EINVAL;
    if ((egid != (gid_t) -1) && !gid_valid(kegid))
        return -EINVAL;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;
    old = current_cred();

    retval = -EPERM;
    if (rgid != (gid_t) -1) {
        if (gid_eq(old->gid, krgid) ||
            gid_eq(old->egid, krgid) ||
            nsown_capable(CAP_SETGID))
            new->gid = krgid;
        else
            goto error;
    }
    if (egid != (gid_t) -1) {
        if (gid_eq(old->gid, kegid) ||
            gid_eq(old->egid, kegid) ||
            gid_eq(old->sgid, kegid) ||
            nsown_capable(CAP_SETGID))
            new->egid = kegid;
        else
            goto error;
    }

    if (rgid != (gid_t) -1 ||
        (egid != (gid_t) -1 && !gid_eq(kegid, old->gid)))
        new->sgid = new->egid;
    new->fsgid = new->egid;

    return commit_creds(new);

error:
    abort_creds(new);
    return retval;
}

/*
 * setgid() is implemented like SysV w/ SAVED_IDS 
 *
 * SMP: Same implicit races as above.
 */
SYSCALL_DEFINE1(setgid, gid_t, gid)
{
    struct user_namespace *ns = current_user_ns();
    const struct cred *old;
    struct cred *new;
    int retval;
    kgid_t kgid;

    kgid = make_kgid(ns, gid);
    if (!gid_valid(kgid))
        return -EINVAL;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;
    old = current_cred();

    retval = -EPERM;
    if (nsown_capable(CAP_SETGID))
        new->gid = new->egid = new->sgid = new->fsgid = kgid;
    else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid))
        new->egid = new->fsgid = kgid;
    else
        goto error;

    return commit_creds(new);

error:
    abort_creds(new);
    return retval;
}

/*
 * change the user struct in a credentials set to match the new UID
 */
static int set_user(struct cred *new)
{
    struct user_struct *new_user;

    new_user = alloc_uid(new->uid);
    if (!new_user)
        return -EAGAIN;

    /*
     * We don't fail in case of NPROC limit excess here because too many
     * poorly written programs don't check set*uid() return code, assuming
     * it never fails if called by root.  We may still enforce NPROC limit
     * for programs doing set*uid()+execve() by harmlessly deferring the
     * failure to the execve() stage.
     */
    if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
            new_user != INIT_USER)
        current->flags |= PF_NPROC_EXCEEDED;
    else
        current->flags &= ~PF_NPROC_EXCEEDED;

    free_uid(new->user);
    new->user = new_user;
    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. 
 */
SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
{
    struct user_namespace *ns = current_user_ns();
    const struct cred *old;
    struct cred *new;
    int retval;
    kuid_t kruid, keuid;

    kruid = make_kuid(ns, ruid);
    keuid = make_kuid(ns, euid);

    if ((ruid != (uid_t) -1) && !uid_valid(kruid))
        return -EINVAL;
    if ((euid != (uid_t) -1) && !uid_valid(keuid))
        return -EINVAL;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;
    old = current_cred();

    retval = -EPERM;
    if (ruid != (uid_t) -1) {
        new->uid = kruid;
        if (!uid_eq(old->uid, kruid) &&
            !uid_eq(old->euid, kruid) &&
            !nsown_capable(CAP_SETUID))
            goto error;
    }

    if (euid != (uid_t) -1) {
        new->euid = keuid;
        if (!uid_eq(old->uid, keuid) &&
            !uid_eq(old->euid, keuid) &&
            !uid_eq(old->suid, keuid) &&
            !nsown_capable(CAP_SETUID))
            goto error;
    }

    if (!uid_eq(new->uid, old->uid)) {
        retval = set_user(new);
        if (retval < 0)
            goto error;
    }
    if (ruid != (uid_t) -1 ||
        (euid != (uid_t) -1 && !uid_eq(keuid, old->uid)))
        new->suid = new->euid;
    new->fsuid = new->euid;

    retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
    if (retval < 0)
        goto error;

    return commit_creds(new);

error:
    abort_creds(new);
    return retval;
}
        
/*
 * 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.  
 */
SYSCALL_DEFINE1(setuid, uid_t, uid)
{
    struct user_namespace *ns = current_user_ns();
    const struct cred *old;
    struct cred *new;
    int retval;
    kuid_t kuid;

    kuid = make_kuid(ns, uid);
    if (!uid_valid(kuid))
        return -EINVAL;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;
    old = current_cred();

    retval = -EPERM;
    if (nsown_capable(CAP_SETUID)) {
        new->suid = new->uid = kuid;
        if (!uid_eq(kuid, old->uid)) {
            retval = set_user(new);
            if (retval < 0)
                goto error;
        }
    } else if (!uid_eq(kuid, old->uid) && !uid_eq(kuid, new->suid)) {
        goto error;
    }

    new->fsuid = new->euid = kuid;

    retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
    if (retval < 0)
        goto error;

    return commit_creds(new);

error:
    abort_creds(new);
    return retval;
}


/*
 * This function implements a generic ability to update ruid, euid,
 * and suid.  This allows you to implement the 4.4 compatible seteuid().
 */
SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
{
    struct user_namespace *ns = current_user_ns();
    const struct cred *old;
    struct cred *new;
    int retval;
    kuid_t kruid, keuid, ksuid;

    kruid = make_kuid(ns, ruid);
    keuid = make_kuid(ns, euid);
    ksuid = make_kuid(ns, suid);

    if ((ruid != (uid_t) -1) && !uid_valid(kruid))
        return -EINVAL;

    if ((euid != (uid_t) -1) && !uid_valid(keuid))
        return -EINVAL;

    if ((suid != (uid_t) -1) && !uid_valid(ksuid))
        return -EINVAL;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;

    old = current_cred();

    retval = -EPERM;
    if (!nsown_capable(CAP_SETUID)) {
        if (ruid != (uid_t) -1        && !uid_eq(kruid, old->uid) &&
            !uid_eq(kruid, old->euid) && !uid_eq(kruid, old->suid))
            goto error;
        if (euid != (uid_t) -1        && !uid_eq(keuid, old->uid) &&
            !uid_eq(keuid, old->euid) && !uid_eq(keuid, old->suid))
            goto error;
        if (suid != (uid_t) -1        && !uid_eq(ksuid, old->uid) &&
            !uid_eq(ksuid, old->euid) && !uid_eq(ksuid, old->suid))
            goto error;
    }

    if (ruid != (uid_t) -1) {
        new->uid = kruid;
        if (!uid_eq(kruid, old->uid)) {
            retval = set_user(new);
            if (retval < 0)
                goto error;
        }
    }
    if (euid != (uid_t) -1)
        new->euid = keuid;
    if (suid != (uid_t) -1)
        new->suid = ksuid;
    new->fsuid = new->euid;

    retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
    if (retval < 0)
        goto error;

    return commit_creds(new);

error:
    abort_creds(new);
    return retval;
}

SYSCALL_DEFINE3(getresuid, uid_t __user *, ruidp, uid_t __user *, euidp, uid_t __user *, suidp)
{
    const struct cred *cred = current_cred();
    int retval;
    uid_t ruid, euid, suid;

    ruid = from_kuid_munged(cred->user_ns, cred->uid);
    euid = from_kuid_munged(cred->user_ns, cred->euid);
    suid = from_kuid_munged(cred->user_ns, cred->suid);

    if (!(retval   = put_user(ruid, ruidp)) &&
        !(retval   = put_user(euid, euidp)))
        retval = put_user(suid, suidp);

    return retval;
}

/*
 * Same as above, but for rgid, egid, sgid.
 */
SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
{
    struct user_namespace *ns = current_user_ns();
    const struct cred *old;
    struct cred *new;
    int retval;
    kgid_t krgid, kegid, ksgid;

    krgid = make_kgid(ns, rgid);
    kegid = make_kgid(ns, egid);
    ksgid = make_kgid(ns, sgid);

    if ((rgid != (gid_t) -1) && !gid_valid(krgid))
        return -EINVAL;
    if ((egid != (gid_t) -1) && !gid_valid(kegid))
        return -EINVAL;
    if ((sgid != (gid_t) -1) && !gid_valid(ksgid))
        return -EINVAL;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;
    old = current_cred();

    retval = -EPERM;
    if (!nsown_capable(CAP_SETGID)) {
        if (rgid != (gid_t) -1        && !gid_eq(krgid, old->gid) &&
            !gid_eq(krgid, old->egid) && !gid_eq(krgid, old->sgid))
            goto error;
        if (egid != (gid_t) -1        && !gid_eq(kegid, old->gid) &&
            !gid_eq(kegid, old->egid) && !gid_eq(kegid, old->sgid))
            goto error;
        if (sgid != (gid_t) -1        && !gid_eq(ksgid, old->gid) &&
            !gid_eq(ksgid, old->egid) && !gid_eq(ksgid, old->sgid))
            goto error;
    }

    if (rgid != (gid_t) -1)
        new->gid = krgid;
    if (egid != (gid_t) -1)
        new->egid = kegid;
    if (sgid != (gid_t) -1)
        new->sgid = ksgid;
    new->fsgid = new->egid;

    return commit_creds(new);

error:
    abort_creds(new);
    return retval;
}

SYSCALL_DEFINE3(getresgid, gid_t __user *, rgidp, gid_t __user *, egidp, gid_t __user *, sgidp)
{
    const struct cred *cred = current_cred();
    int retval;
    gid_t rgid, egid, sgid;

    rgid = from_kgid_munged(cred->user_ns, cred->gid);
    egid = from_kgid_munged(cred->user_ns, cred->egid);
    sgid = from_kgid_munged(cred->user_ns, cred->sgid);

    if (!(retval   = put_user(rgid, rgidp)) &&
        !(retval   = put_user(egid, egidp)))
        retval = put_user(sgid, sgidp);

    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..
 */
SYSCALL_DEFINE1(setfsuid, uid_t, uid)
{
    const struct cred *old;
    struct cred *new;
    uid_t old_fsuid;
    kuid_t kuid;

    old = current_cred();
    old_fsuid = from_kuid_munged(old->user_ns, old->fsuid);

    kuid = make_kuid(old->user_ns, uid);
    if (!uid_valid(kuid))
        return old_fsuid;

    new = prepare_creds();
    if (!new)
        return old_fsuid;

    if (uid_eq(kuid, old->uid)  || uid_eq(kuid, old->euid)  ||
        uid_eq(kuid, old->suid) || uid_eq(kuid, old->fsuid) ||
        nsown_capable(CAP_SETUID)) {
        if (!uid_eq(kuid, old->fsuid)) {
            new->fsuid = kuid;
            if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
                goto change_okay;
        }
    }

    abort_creds(new);
    return old_fsuid;

change_okay:
    commit_creds(new);
    return old_fsuid;
}

/*
 * Samma på svenska..
 */
SYSCALL_DEFINE1(setfsgid, gid_t, gid)
{
    const struct cred *old;
    struct cred *new;
    gid_t old_fsgid;
    kgid_t kgid;

    old = current_cred();
    old_fsgid = from_kgid_munged(old->user_ns, old->fsgid);

    kgid = make_kgid(old->user_ns, gid);
    if (!gid_valid(kgid))
        return old_fsgid;

    new = prepare_creds();
    if (!new)
        return old_fsgid;

    if (gid_eq(kgid, old->gid)  || gid_eq(kgid, old->egid)  ||
        gid_eq(kgid, old->sgid) || gid_eq(kgid, old->fsgid) ||
        nsown_capable(CAP_SETGID)) {
        if (!gid_eq(kgid, old->fsgid)) {
            new->fsgid = kgid;
            goto change_okay;
        }
    }

    abort_creds(new);
    return old_fsgid;

change_okay:
    commit_creds(new);
    return old_fsgid;
}

void do_sys_times(struct tms *tms)
{
    cputime_t tgutime, tgstime, cutime, cstime;

    spin_lock_irq(&current->sighand->siglock);
    thread_group_times(current, &tgutime, &tgstime);
    cutime = current->signal->cutime;
    cstime = current->signal->cstime;
    spin_unlock_irq(&current->sighand->siglock);
    tms->tms_utime = cputime_to_clock_t(tgutime);
    tms->tms_stime = cputime_to_clock_t(tgstime);
    tms->tms_cutime = cputime_to_clock_t(cutime);
    tms->tms_cstime = cputime_to_clock_t(cstime);
}

SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
{
    if (tbuf) {
        struct tms tmp;

        do_sys_times(&tmp);
        if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
            return -EFAULT;
    }
    force_successful_syscall_return();
    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
 */
SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
{
    struct task_struct *p;
    struct task_struct *group_leader = current->group_leader;
    struct pid *pgrp;
    int err;

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

    /* 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_vpid(pid);
    if (!p)
        goto out;

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

    if (same_thread_group(p->real_parent, group_leader)) {
        err = -EPERM;
        if (task_session(p) != task_session(group_leader))
            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;

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

        pgrp = find_vpid(pgid);
        g = pid_task(pgrp, PIDTYPE_PGID);
        if (!g || task_session(g) != task_session(group_leader))
            goto out;
    }

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

    if (task_pgrp(p) != pgrp)
        change_pid(p, PIDTYPE_PGID, pgrp);

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

SYSCALL_DEFINE1(getpgid, pid_t, pid)
{
    struct task_struct *p;
    struct pid *grp;
    int retval;

    rcu_read_lock();
    if (!pid)
        grp = task_pgrp(current);
    else {
        retval = -ESRCH;
        p = find_task_by_vpid(pid);
        if (!p)
            goto out;
        grp = task_pgrp(p);
        if (!grp)
            goto out;

        retval = security_task_getpgid(p);
        if (retval)
            goto out;
    }
    retval = pid_vnr(grp);
out:
    rcu_read_unlock();
    return retval;
}

#ifdef __ARCH_WANT_SYS_GETPGRP

SYSCALL_DEFINE0(getpgrp)
{
    return sys_getpgid(0);
}

#endif

SYSCALL_DEFINE1(getsid, pid_t, pid)
{
    struct task_struct *p;
    struct pid *sid;
    int retval;

    rcu_read_lock();
    if (!pid)
        sid = task_session(current);
    else {
        retval = -ESRCH;
        p = find_task_by_vpid(pid);
        if (!p)
            goto out;
        sid = task_session(p);
        if (!sid)
            goto out;

        retval = security_task_getsid(p);
        if (retval)
            goto out;
    }
    retval = pid_vnr(sid);
out:
    rcu_read_unlock();
    return retval;
}

SYSCALL_DEFINE0(setsid)
{
    struct task_struct *group_leader = current->group_leader;
    struct pid *sid = task_pid(group_leader);
    pid_t session = pid_vnr(sid);
    int err = -EPERM;

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

    /* Fail if a process group id already exists that equals the
     * proposed session id.
     */
    if (pid_task(sid, PIDTYPE_PGID))
        goto out;

    group_leader->signal->leader = 1;
    __set_special_pids(sid);

    proc_clear_tty(group_leader);

    err = session;
out:
    write_unlock_irq(&tasklist_lock);
    if (err > 0) {
        proc_sid_connector(group_leader);
        sched_autogroup_create_attach(group_leader);
    }
    return err;
}

DECLARE_RWSEM(uts_sem);

#ifdef COMPAT_UTS_MACHINE
#define override_architecture(name) \
    (personality(current->personality) == PER_LINUX32 && \
     copy_to_user(name->machine, COMPAT_UTS_MACHINE, \
              sizeof(COMPAT_UTS_MACHINE)))
#else
#define override_architecture(name) 0
#endif

/*
 * Work around broken programs that cannot handle "Linux 3.0".
 * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40
 */
static int override_release(char __user *release, size_t len)
{
    int ret = 0;

    if (current->personality & UNAME26) {
        const char *rest = UTS_RELEASE;
        char buf[65] = { 0 };
        int ndots = 0;
        unsigned v;
        size_t copy;

        while (*rest) {
            if (*rest == '.' && ++ndots >= 3)
                break;
            if (!isdigit(*rest) && *rest != '.')
                break;
            rest++;
        }
        v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
        copy = clamp_t(size_t, len, 1, sizeof(buf));
        copy = scnprintf(buf, copy, "2.6.%u%s", v, rest);
        ret = copy_to_user(release, buf, copy + 1);
    }
    return ret;
}

SYSCALL_DEFINE1(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);

    if (!errno && override_release(name->release, sizeof(name->release)))
        errno = -EFAULT;
    if (!errno && override_architecture(name))
        errno = -EFAULT;
    return errno;
}

#ifdef __ARCH_WANT_SYS_OLD_UNAME
/*
 * Old cruft
 */
SYSCALL_DEFINE1(uname, struct old_utsname __user *, name)
{
    int error = 0;

    if (!name)
        return -EFAULT;

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

    if (!error && override_release(name->release, sizeof(name->release)))
        error = -EFAULT;
    if (!error && override_architecture(name))
        error = -EFAULT;
    return error;
}

SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name)
{
    int error;

    if (!name)
        return -EFAULT;
    if (!access_ok(VERIFY_WRITE, name, sizeof(struct oldold_utsname)))
        return -EFAULT;

    down_read(&uts_sem);
    error = __copy_to_user(&name->sysname, &utsname()->sysname,
                   __OLD_UTS_LEN);
    error |= __put_user(0, name->sysname + __OLD_UTS_LEN);
    error |= __copy_to_user(&name->nodename, &utsname()->nodename,
                __OLD_UTS_LEN);
    error |= __put_user(0, name->nodename + __OLD_UTS_LEN);
    error |= __copy_to_user(&name->release, &utsname()->release,
                __OLD_UTS_LEN);
    error |= __put_user(0, name->release + __OLD_UTS_LEN);
    error |= __copy_to_user(&name->version, &utsname()->version,
                __OLD_UTS_LEN);
    error |= __put_user(0, name->version + __OLD_UTS_LEN);
    error |= __copy_to_user(&name->machine, &utsname()->machine,
                __OLD_UTS_LEN);
    error |= __put_user(0, name->machine + __OLD_UTS_LEN);
    up_read(&uts_sem);

    if (!error && override_architecture(name))
        error = -EFAULT;
    if (!error && override_release(name->release, sizeof(name->release)))
        error = -EFAULT;
    return error ? -EFAULT : 0;
}
#endif

SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
{
    int errno;
    char tmp[__NEW_UTS_LEN];

    if (!ns_capable(current->nsproxy->uts_ns->user_ns, 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)) {
        struct new_utsname *u = utsname();

        memcpy(u->nodename, tmp, len);
        memset(u->nodename + len, 0, sizeof(u->nodename) - len);
        errno = 0;
        uts_proc_notify(UTS_PROC_HOSTNAME);
    }
    up_write(&uts_sem);
    return errno;
}

#ifdef __ARCH_WANT_SYS_GETHOSTNAME

SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
{
    int i, errno;
    struct new_utsname *u;

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

#endif

/*
 * Only setdomainname; getdomainname can be implemented by calling
 * uname()
 */
SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
{
    int errno;
    char tmp[__NEW_UTS_LEN];

    if (!ns_capable(current->nsproxy->uts_ns->user_ns, 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)) {
        struct new_utsname *u = utsname();

        memcpy(u->domainname, tmp, len);
        memset(u->domainname + len, 0, sizeof(u->domainname) - len);
        errno = 0;
        uts_proc_notify(UTS_PROC_DOMAINNAME);
    }
    up_write(&uts_sem);
    return errno;
}

SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
{
    struct rlimit value;
    int ret;

    ret = do_prlimit(current, resource, NULL, &value);
    if (!ret)
        ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;

    return ret;
}

#ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT

/*
 *  Back compatibility for getrlimit. Needed for some apps.
 */
 
SYSCALL_DEFINE2(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

static inline bool rlim64_is_infinity(__u64 rlim64)
{
#if BITS_PER_LONG < 64
    return rlim64 >= ULONG_MAX;
#else
    return rlim64 == RLIM64_INFINITY;
#endif
}

static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64)
{
    if (rlim->rlim_cur == RLIM_INFINITY)
        rlim64->rlim_cur = RLIM64_INFINITY;
    else
        rlim64->rlim_cur = rlim->rlim_cur;
    if (rlim->rlim_max == RLIM_INFINITY)
        rlim64->rlim_max = RLIM64_INFINITY;
    else
        rlim64->rlim_max = rlim->rlim_max;
}

static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim)
{
    if (rlim64_is_infinity(rlim64->rlim_cur))
        rlim->rlim_cur = RLIM_INFINITY;
    else
        rlim->rlim_cur = (unsigned long)rlim64->rlim_cur;
    if (rlim64_is_infinity(rlim64->rlim_max))
        rlim->rlim_max = RLIM_INFINITY;
    else
        rlim->rlim_max = (unsigned long)rlim64->rlim_max;
}

/* make sure you are allowed to change @tsk limits before calling this */
int do_prlimit(struct task_struct *tsk, unsigned int resource,
        struct rlimit *new_rlim, struct rlimit *old_rlim)
{
    struct rlimit *rlim;
    int retval = 0;

    if (resource >= RLIM_NLIMITS)
        return -EINVAL;
    if (new_rlim) {
        if (new_rlim->rlim_cur > new_rlim->rlim_max)
            return -EINVAL;
        if (resource == RLIMIT_NOFILE &&
                new_rlim->rlim_max > sysctl_nr_open)
            return -EPERM;
    }

    /* protect tsk->signal and tsk->sighand from disappearing */
    read_lock(&tasklist_lock);
    if (!tsk->sighand) {
        retval = -ESRCH;
        goto out;
    }

    rlim = tsk->signal->rlim + resource;
    task_lock(tsk->group_leader);
    if (new_rlim) {
        /* Keep the capable check against init_user_ns until
           cgroups can contain all limits */
        if (new_rlim->rlim_max > rlim->rlim_max &&
                !capable(CAP_SYS_RESOURCE))
            retval = -EPERM;
        if (!retval)
            retval = security_task_setrlimit(tsk->group_leader,
                    resource, new_rlim);
        if (resource == RLIMIT_CPU && new_rlim->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
             */
            new_rlim->rlim_cur = 1;
        }
    }
    if (!retval) {
        if (old_rlim)
            *old_rlim = *rlim;
        if (new_rlim)
            *rlim = *new_rlim;
    }
    task_unlock(tsk->group_leader);

    /*
     * 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 (!retval && new_rlim && resource == RLIMIT_CPU &&
             new_rlim->rlim_cur != RLIM_INFINITY)
        update_rlimit_cpu(tsk, new_rlim->rlim_cur);
out:
    read_unlock(&tasklist_lock);
    return retval;
}

/* rcu lock must be held */
static int check_prlimit_permission(struct task_struct *task)
{
    const struct cred *cred = current_cred(), *tcred;

    if (current == task)
        return 0;

    tcred = __task_cred(task);
    if (uid_eq(cred->uid, tcred->euid) &&
        uid_eq(cred->uid, tcred->suid) &&
        uid_eq(cred->uid, tcred->uid)  &&
        gid_eq(cred->gid, tcred->egid) &&
        gid_eq(cred->gid, tcred->sgid) &&
        gid_eq(cred->gid, tcred->gid))
        return 0;
    if (ns_capable(tcred->user_ns, CAP_SYS_RESOURCE))
        return 0;

    return -EPERM;
}

SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
        const struct rlimit64 __user *, new_rlim,
        struct rlimit64 __user *, old_rlim)
{
    struct rlimit64 old64, new64;
    struct rlimit old, new;
    struct task_struct *tsk;
    int ret;

    if (new_rlim) {
        if (copy_from_user(&new64, new_rlim, sizeof(new64)))
            return -EFAULT;
        rlim64_to_rlim(&new64, &new);
    }

    rcu_read_lock();
    tsk = pid ? find_task_by_vpid(pid) : current;
    if (!tsk) {
        rcu_read_unlock();
        return -ESRCH;
    }
    ret = check_prlimit_permission(tsk);
    if (ret) {
        rcu_read_unlock();
        return ret;
    }
    get_task_struct(tsk);
    rcu_read_unlock();

    ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
            old_rlim ? &old : NULL);

    if (!ret && old_rlim) {
        rlim_to_rlim64(&old, &old64);
        if (copy_to_user(old_rlim, &old64, sizeof(old64)))
            ret = -EFAULT;
    }

    put_task_struct(tsk);
    return ret;
}

SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
{
    struct rlimit new_rlim;

    if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
        return -EFAULT;
    return do_prlimit(current, resource, &new_rlim, NULL);
}

/*
 * 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 accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
{
    r->ru_nvcsw += t->nvcsw;
    r->ru_nivcsw += t->nivcsw;
    r->ru_minflt += t->min_flt;
    r->ru_majflt += t->maj_flt;
    r->ru_inblock += task_io_get_inblock(t);
    r->ru_oublock += task_io_get_oublock(t);
}

static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
{
    struct task_struct *t;
    unsigned long flags;
    cputime_t tgutime, tgstime, utime, stime;
    unsigned long maxrss = 0;

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

    if (who == RUSAGE_THREAD) {
        task_times(current, &utime, &stime);
        accumulate_thread_rusage(p, r);
        maxrss = p->signal->maxrss;
        goto out;
    }

    if (!lock_task_sighand(p, &flags))
        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;
            r->ru_inblock = p->signal->cinblock;
            r->ru_oublock = p->signal->coublock;
            maxrss = p->signal->cmaxrss;

            if (who == RUSAGE_CHILDREN)
                break;

        case RUSAGE_SELF:
            thread_group_times(p, &tgutime, &tgstime);
            utime += tgutime;
            stime += tgstime;
            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;
            r->ru_inblock += p->signal->inblock;
            r->ru_oublock += p->signal->oublock;
            if (maxrss < p->signal->maxrss)
                maxrss = p->signal->maxrss;
            t = p;
            do {
                accumulate_thread_rusage(t, r);
                t = next_thread(t);
            } while (t != p);
            break;

        default:
            BUG();
    }
    unlock_task_sighand(p, &flags);

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

    if (who != RUSAGE_CHILDREN) {
        struct mm_struct *mm = get_task_mm(p);
        if (mm) {
            setmax_mm_hiwater_rss(&maxrss, mm);
            mmput(mm);
        }
    }
    r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
}

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;
}

SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
{
    if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
        who != RUSAGE_THREAD)
        return -EINVAL;
    return getrusage(current, who, ru);
}

SYSCALL_DEFINE1(umask, int, mask)
{
    mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
    return mask;
}

#ifdef CONFIG_CHECKPOINT_RESTORE
static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
{
    struct fd exe;
    struct dentry *dentry;
    int err;

    exe = fdget(fd);
    if (!exe.file)
        return -EBADF;

    dentry = exe.file->f_path.dentry;

    /*
     * Because the original mm->exe_file points to executable file, make
     * sure that this one is executable as well, to avoid breaking an
     * overall picture.
     */
    err = -EACCES;
    if (!S_ISREG(dentry->d_inode->i_mode)   ||
        exe.file->f_path.mnt->mnt_flags & MNT_NOEXEC)
        goto exit;

    err = inode_permission(dentry->d_inode, MAY_EXEC);
    if (err)
        goto exit;

    down_write(&mm->mmap_sem);

    /*
     * Forbid mm->exe_file change if old file still mapped.
     */
    err = -EBUSY;
    if (mm->exe_file) {
        struct vm_area_struct *vma;

        for (vma = mm->mmap; vma; vma = vma->vm_next)
            if (vma->vm_file &&
                path_equal(&vma->vm_file->f_path,
                       &mm->exe_file->f_path))
                goto exit_unlock;
    }

    /*
     * The symlink can be changed only once, just to disallow arbitrary
     * transitions malicious software might bring in. This means one
     * could make a snapshot over all processes running and monitor
     * /proc/pid/exe changes to notice unusual activity if needed.
     */
    err = -EPERM;
    if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
        goto exit_unlock;

    err = 0;
    set_mm_exe_file(mm, exe.file);  /* this grabs a reference to exe.file */
exit_unlock:
    up_write(&mm->mmap_sem);

exit:
    fdput(exe);
    return err;
}

static int prctl_set_mm(int opt, unsigned long addr,
            unsigned long arg4, unsigned long arg5)
{
    unsigned long rlim = rlimit(RLIMIT_DATA);
    struct mm_struct *mm = current->mm;
    struct vm_area_struct *vma;
    int error;

    if (arg5 || (arg4 && opt != PR_SET_MM_AUXV))
        return -EINVAL;

    if (!capable(CAP_SYS_RESOURCE))
        return -EPERM;

    if (opt == PR_SET_MM_EXE_FILE)
        return prctl_set_mm_exe_file(mm, (unsigned int)addr);

    if (addr >= TASK_SIZE || addr < mmap_min_addr)
        return -EINVAL;

    error = -EINVAL;

    down_read(&mm->mmap_sem);
    vma = find_vma(mm, addr);

    switch (opt) {
    case PR_SET_MM_START_CODE:
        mm->start_code = addr;
        break;
    case PR_SET_MM_END_CODE:
        mm->end_code = addr;
        break;
    case PR_SET_MM_START_DATA:
        mm->start_data = addr;
        break;
    case PR_SET_MM_END_DATA:
        mm->end_data = addr;
        break;

    case PR_SET_MM_START_BRK:
        if (addr <= mm->end_data)
            goto out;

        if (rlim < RLIM_INFINITY &&
            (mm->brk - addr) +
            (mm->end_data - mm->start_data) > rlim)
            goto out;

        mm->start_brk = addr;
        break;

    case PR_SET_MM_BRK:
        if (addr <= mm->end_data)
            goto out;

        if (rlim < RLIM_INFINITY &&
            (addr - mm->start_brk) +
            (mm->end_data - mm->start_data) > rlim)
            goto out;

        mm->brk = addr;
        break;

    /*
     * If command line arguments and environment
     * are placed somewhere else on stack, we can
     * set them up here, ARG_START/END to setup
     * command line argumets and ENV_START/END
     * for environment.
     */
    case PR_SET_MM_START_STACK:
    case PR_SET_MM_ARG_START:
    case PR_SET_MM_ARG_END:
    case PR_SET_MM_ENV_START:
    case PR_SET_MM_ENV_END:
        if (!vma) {
            error = -EFAULT;
            goto out;
        }
        if (opt == PR_SET_MM_START_STACK)
            mm->start_stack = addr;
        else if (opt == PR_SET_MM_ARG_START)
            mm->arg_start = addr;
        else if (opt == PR_SET_MM_ARG_END)
            mm->arg_end = addr;
        else if (opt == PR_SET_MM_ENV_START)
            mm->env_start = addr;
        else if (opt == PR_SET_MM_ENV_END)
            mm->env_end = addr;
        break;

    /*
     * This doesn't move auxiliary vector itself
     * since it's pinned to mm_struct, but allow
     * to fill vector with new values. It's up
     * to a caller to provide sane values here
     * otherwise user space tools which use this
     * vector might be unhappy.
     */
    case PR_SET_MM_AUXV: {
        unsigned long user_auxv[AT_VECTOR_SIZE];

        if (arg4 > sizeof(user_auxv))
            goto out;
        up_read(&mm->mmap_sem);

        if (copy_from_user(user_auxv, (const void __user *)addr, arg4))
            return -EFAULT;

        /* Make sure the last entry is always AT_NULL */
        user_auxv[AT_VECTOR_SIZE - 2] = 0;
        user_auxv[AT_VECTOR_SIZE - 1] = 0;

        BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv));

        task_lock(current);
        memcpy(mm->saved_auxv, user_auxv, arg4);
        task_unlock(current);

        return 0;
    }
    default:
        goto out;
    }

    error = 0;
out:
    up_read(&mm->mmap_sem);
    return error;
}

static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
{
    return put_user(me->clear_child_tid, tid_addr);
}

#else /* CONFIG_CHECKPOINT_RESTORE */
static int prctl_set_mm(int opt, unsigned long addr,
            unsigned long arg4, unsigned long arg5)
{
    return -EINVAL;
}
static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
{
    return -EINVAL;
}
#endif

SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
        unsigned long, arg4, unsigned long, arg5)
{
    struct task_struct *me = current;
    unsigned char comm[sizeof(me->comm)];
    long error;

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

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

        case PR_SET_UNALIGN:
            error = SET_UNALIGN_CTL(me, arg2);
            break;
        case PR_GET_UNALIGN:
            error = GET_UNALIGN_CTL(me, arg2);
            break;
        case PR_SET_FPEMU:
            error = SET_FPEMU_CTL(me, arg2);
            break;
        case PR_GET_FPEMU:
            error = GET_FPEMU_CTL(me, arg2);
            break;
        case PR_SET_FPEXC:
            error = SET_FPEXC_CTL(me, arg2);
            break;
        case PR_GET_FPEXC:
            error = GET_FPEXC_CTL(me, arg2);
            break;
        case PR_GET_TIMING:
            error = PR_TIMING_STATISTICAL;
            break;
        case PR_SET_TIMING:
            if (arg2 != PR_TIMING_STATISTICAL)
                error = -EINVAL;
            break;
        case PR_SET_NAME:
            comm[sizeof(me->comm)-1] = 0;
            if (strncpy_from_user(comm, (char __user *)arg2,
                          sizeof(me->comm) - 1) < 0)
                return -EFAULT;
            set_task_comm(me, comm);
            proc_comm_connector(me);
            break;
        case PR_GET_NAME:
            get_task_comm(comm, me);
            if (copy_to_user((char __user *)arg2, comm,
                     sizeof(comm)))
                return -EFAULT;
            break;
        case PR_GET_ENDIAN:
            error = GET_ENDIAN(me, arg2);
            break;
        case PR_SET_ENDIAN:
            error = SET_ENDIAN(me, arg2);
            break;
        case PR_GET_SECCOMP:
            error = prctl_get_seccomp();
            break;
        case PR_SET_SECCOMP:
            error = prctl_set_seccomp(arg2, (char __user *)arg3);
            break;
        case PR_GET_TSC:
            error = GET_TSC_CTL(arg2);
            break;
        case PR_SET_TSC:
            error = SET_TSC_CTL(arg2);
            break;
        case PR_TASK_PERF_EVENTS_DISABLE:
            error = perf_event_task_disable();
            break;
        case PR_TASK_PERF_EVENTS_ENABLE:
            error = perf_event_task_enable();
            break;
        case PR_GET_TIMERSLACK:
            error = current->timer_slack_ns;
            break;
        case PR_SET_TIMERSLACK:
            if (arg2 <= 0)
                current->timer_slack_ns =
                    current->default_timer_slack_ns;
            else
                current->timer_slack_ns = arg2;
            break;
        case PR_MCE_KILL:
            if (arg4 | arg5)
                return -EINVAL;
            switch (arg2) {
            case PR_MCE_KILL_CLEAR:
                if (arg3 != 0)
                    return -EINVAL;
                current->flags &= ~PF_MCE_PROCESS;
                break;
            case PR_MCE_KILL_SET:
                current->flags |= PF_MCE_PROCESS;
                if (arg3 == PR_MCE_KILL_EARLY)
                    current->flags |= PF_MCE_EARLY;
                else if (arg3 == PR_MCE_KILL_LATE)
                    current->flags &= ~PF_MCE_EARLY;
                else if (arg3 == PR_MCE_KILL_DEFAULT)
                    current->flags &=
                        ~(PF_MCE_EARLY|PF_MCE_PROCESS);
                else
                    return -EINVAL;
                break;
            default:
                return -EINVAL;
            }
            break;
        case PR_MCE_KILL_GET:
            if (arg2 | arg3 | arg4 | arg5)
                return -EINVAL;
            if (current->flags & PF_MCE_PROCESS)
                error = (current->flags & PF_MCE_EARLY) ?
                    PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE;
            else
                error = PR_MCE_KILL_DEFAULT;
            break;
        case PR_SET_MM:
            error = prctl_set_mm(arg2, arg3, arg4, arg5);
            break;
        case PR_GET_TID_ADDRESS:
            error = prctl_get_tid_address(me, (int __user **)arg2);
            break;
        case PR_SET_CHILD_SUBREAPER:
            me->signal->is_child_subreaper = !!arg2;
            break;
        case PR_GET_CHILD_SUBREAPER:
            error = put_user(me->signal->is_child_subreaper,
                     (int __user *) arg2);
            break;
        case PR_SET_NO_NEW_PRIVS:
            if (arg2 != 1 || arg3 || arg4 || arg5)
                return -EINVAL;

            current->no_new_privs = 1;
            break;
        case PR_GET_NO_NEW_PRIVS:
            if (arg2 || arg3 || arg4 || arg5)
                return -EINVAL;
            return current->no_new_privs ? 1 : 0;
        default:
            error = -EINVAL;
            break;
    }
    return error;
}

SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
        struct getcpu_cache __user *, unused)
{
    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);
    return err ? -EFAULT : 0;
}

char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";

static void argv_cleanup(struct subprocess_info *info)
{
    argv_free(info->argv);
}

static int __orderly_poweroff(void)
{
    int argc;
    char **argv;
    static char *envp[] = {
        "HOME=/",
        "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
        NULL
    };
    int ret;

    argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
    if (argv == NULL) {
        printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
               __func__, poweroff_cmd);
        return -ENOMEM;
    }

    ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_WAIT_EXEC,
                      NULL, argv_cleanup, NULL);
    if (ret == -ENOMEM)
        argv_free(argv);

    return ret;
}

int orderly_poweroff(bool force)
{
    int ret = __orderly_poweroff();

    if (ret && force) {
        printk(KERN_WARNING "Failed to start orderly shutdown: "
               "forcing the issue\n");

        /*
         * I guess this should try to kick off some daemon to sync and
         * poweroff asap.  Or not even bother syncing if we're doing an
         * emergency shutdown?
         */
        emergency_sync();
        kernel_power_off();
    }

    return ret;
}
EXPORT_SYMBOL_GPL(orderly_poweroff);