/*
 *  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;
}

/**
 *      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)
{
        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();
}

/**
 *      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);

/**
 *      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);
        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();
}
/**
 *      kernel_halt - halt the system
 *
 *      Shutdown everything and perform a clean system halt.
 */
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);

/**
 *      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);
        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;
}

/**
 * orderly_poweroff - Trigger an orderly system poweroff
 * @force: force poweroff if command execution fails
 *
 * This may be called from any context to trigger a system shutdown.
 * If the orderly shutdown fails, it will force an immediate shutdown.
 */
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);