text: /*
   *  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/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/binfmts.h>
  
  #include <linux/sched.h>
  #include <linux/rcupdate.h>
  #include <linux/uidgid.h>
  #include <linux/cred.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);
  
  /*
   * 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 < MIN_NICE)
  		niceval = MIN_NICE;
  	if (niceval > MAX_NICE)
  		niceval = MAX_NICE;
  
  	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 = nice_to_rlimit(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 = nice_to_rlimit(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 = nice_to_rlimit(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;
  }
  
  /*
   * 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) ||
  		    ns_capable(old->user_ns, 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) ||
  		    ns_capable(old->user_ns, 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 (ns_capable(old->user_ns, 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) &&
  		    !ns_capable(old->user_ns, 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) &&
  		    !ns_capable(old->user_ns, 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 (ns_capable(old->user_ns, 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 (!ns_capable(old->user_ns, 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 (!ns_capable(old->user_ns, 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) ||
  	    ns_capable(old->user_ns, 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) ||
  	    ns_capable(old->user_ns, 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;
  }
  
  /**
   * sys_getpid - return the thread group id of the current process
   *
   * Note, despite the name, this returns the tgid not the pid.  The tgid and
   * the pid are identical unless CLONE_THREAD was specified on clone() in
   * which case the tgid is the same in all threads of the same group.
   *
   * This is SMP safe as current->tgid does not change.
   */
  SYSCALL_DEFINE0(getpid)
  {
  	return task_tgid_vnr(current);
  }
  
  /* Thread ID - the internal kernel "pid" */
  SYSCALL_DEFINE0(gettid)
  {
  	return task_pid_vnr(current);
  }
  
  /*
   * Accessing ->real_parent is not SMP-safe, it could
   * change from under us. However, we can use a stale
   * value of ->real_parent under rcu_read_lock(), see
   * release_task()->call_rcu(delayed_put_task_struct).
   */
  SYSCALL_DEFINE0(getppid)
  {
  	int pid;
  
  	rcu_read_lock();
  	pid = task_tgid_vnr(rcu_dereference(current->real_parent));
  	rcu_read_unlock();
  
  	return pid;
  }
  
  SYSCALL_DEFINE0(getuid)
  {
  	/* Only we change this so SMP safe */
  	return from_kuid_munged(current_user_ns(), current_uid());
  }
  
  SYSCALL_DEFINE0(geteuid)
  {
  	/* Only we change this so SMP safe */
  	return from_kuid_munged(current_user_ns(), current_euid());
  }
  
  SYSCALL_DEFINE0(getgid)
  {
  	/* Only we change this so SMP safe */
  	return from_kgid_munged(current_user_ns(), current_gid());
  }
  
  SYSCALL_DEFINE0(getegid)
  {
  	/* Only we change this so SMP safe */
  	return from_kgid_munged(current_user_ns(), current_egid());
  }
  
  void do_sys_times(struct tms *tms)
  {
  	cputime_t tgutime, tgstime, cutime, cstime;
  
  	spin_lock_irq(&current->sighand->siglock);
  	thread_group_cputime_adjusted(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
   *
   * !PF_FORKNOEXEC check to conform completely to POSIX.
   */
  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->flags & PF_FORKNOEXEC))
  			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;
  }
  
  static void set_special_pids(struct pid *pid)
  {
  	struct task_struct *curr = current->group_leader;
  
  	if (task_session(curr) != pid)
  		change_pid(curr, PIDTYPE_SID, pid);
  
  	if (task_pgrp(curr) != pid)
  		change_pid(curr, PIDTYPE_PGID, pid);
  }
  
  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_cputime_adjusted(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_cputime_adjusted(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);
  			} while_each_thread(p, t);
  			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);
  }
  
  #ifdef CONFIG_COMPAT
  COMPAT_SYSCALL_DEFINE2(getrusage, int, who, struct compat_rusage __user *, ru)
  {
  	struct rusage r;
  
  	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
  	    who != RUSAGE_THREAD)
  		return -EINVAL;
  
  	k_getrusage(current, who, &r);
  	return put_compat_rusage(&r, ru);
  }
  #endif
  
  SYSCALL_DEFINE1(umask, int, mask)
  {
  	mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
  	return mask;
  }
  
  static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
  {
  	struct fd exe;
  	struct inode *inode;
  	int err;
  
  	exe = fdget(fd);
  	if (!exe.file)
  		return -EBADF;
  
  	inode = file_inode(exe.file);
  
  	/*
  	 * 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(inode->i_mode)	||
  	    exe.file->f_path.mnt->mnt_flags & MNT_NOEXEC)
  		goto exit;
  
  	err = inode_permission(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;
  }
  
  #ifdef CONFIG_CHECKPOINT_RESTORE
  static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
  {
  	return put_user(me->clear_child_tid, tid_addr);
  }
  #else
  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 != SUID_DUMP_DISABLE && arg2 != SUID_DUMP_USER) {
  			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;
  	case PR_GET_THP_DISABLE:
  		if (arg2 || arg3 || arg4 || arg5)
  			return -EINVAL;
  		error = !!(me->mm->def_flags & VM_NOHUGEPAGE);
  		break;
  	case PR_SET_THP_DISABLE:
  		if (arg3 || arg4 || arg5)
  			return -EINVAL;
  		down_write(&me->mm->mmap_sem);
  		if (arg2)
  			me->mm->def_flags |= VM_NOHUGEPAGE;
  		else
  			me->mm->def_flags &= ~VM_NOHUGEPAGE;
  		up_write(&me->mm->mmap_sem);
  		break;
  	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;
  }
  
  /**
   * do_sysinfo - fill in sysinfo struct
   * @info: pointer to buffer to fill
   */
  static int do_sysinfo(struct sysinfo *info)
  {
  	unsigned long mem_total, sav_total;
  	unsigned int mem_unit, bitcount;
  	struct timespec tp;
  
  	memset(info, 0, sizeof(struct sysinfo));
  
  	get_monotonic_boottime(&tp);
  	info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
  
  	get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
  
  	info->procs = nr_threads;
  
  	si_meminfo(info);
  	si_swapinfo(info);
  
  	/*
  	 * If the sum of all the available memory (i.e. ram + swap)
  	 * is less than can be stored in a 32 bit unsigned long then
  	 * we can be binary compatible with 2.2.x kernels.  If not,
  	 * well, in that case 2.2.x was broken anyways...
  	 *
  	 *  -Erik Andersen <andersee@debian.org>
  	 */
  
  	mem_total = info->totalram + info->totalswap;
  	if (mem_total < info->totalram || mem_total < info->totalswap)
  		goto out;
  	bitcount = 0;
  	mem_unit = info->mem_unit;
  	while (mem_unit > 1) {
  		bitcount++;
  		mem_unit >>= 1;
  		sav_total = mem_total;
  		mem_total <<= 1;
  		if (mem_total < sav_total)
  			goto out;
  	}
  
  	/*
  	 * If mem_total did not overflow, multiply all memory values by
  	 * info->mem_unit and set it to 1.  This leaves things compatible
  	 * with 2.2.x, and also retains compatibility with earlier 2.4.x
  	 * kernels...
  	 */
  
  	info->mem_unit = 1;
  	info->totalram <<= bitcount;
  	info->freeram <<= bitcount;
  	info->sharedram <<= bitcount;
  	info->bufferram <<= bitcount;
  	info->totalswap <<= bitcount;
  	info->freeswap <<= bitcount;
  	info->totalhigh <<= bitcount;
  	info->freehigh <<= bitcount;
  
  out:
  	return 0;
  }
  
  SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
  {
  	struct sysinfo val;
  
  	do_sysinfo(&val);
  
  	if (copy_to_user(info, &val, sizeof(struct sysinfo)))
  		return -EFAULT;
  
  	return 0;
  }
  
  #ifdef CONFIG_COMPAT
  struct compat_sysinfo {
  	s32 uptime;
  	u32 loads[3];
  	u32 totalram;
  	u32 freeram;
  	u32 sharedram;
  	u32 bufferram;
  	u32 totalswap;
  	u32 freeswap;
  	u16 procs;
  	u16 pad;
  	u32 totalhigh;
  	u32 freehigh;
  	u32 mem_unit;
  	char _f[20-2*sizeof(u32)-sizeof(int)];
  };
  
  COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info)
  {
  	struct sysinfo s;
  
  	do_sysinfo(&s);
  
  	/* Check to see if any memory value is too large for 32-bit and scale
  	 *  down if needed
  	 */
  	if ((s.totalram >> 32) || (s.totalswap >> 32)) {
  		int bitcount = 0;
  
  		while (s.mem_unit < PAGE_SIZE) {
  			s.mem_unit <<= 1;
  			bitcount++;
  		}
  
  		s.totalram >>= bitcount;
  		s.freeram >>= bitcount;
  		s.sharedram >>= bitcount;
  		s.bufferram >>= bitcount;
  		s.totalswap >>= bitcount;
  		s.freeswap >>= bitcount;
  		s.totalhigh >>= bitcount;
  		s.freehigh >>= bitcount;
  	}
  
  	if (!access_ok(VERIFY_WRITE, info, sizeof(struct compat_sysinfo)) ||
  	    __put_user(s.uptime, &info->uptime) ||
  	    __put_user(s.loads[0], &info->loads[0]) ||
  	    __put_user(s.loads[1], &info->loads[1]) ||
  	    __put_user(s.loads[2], &info->loads[2]) ||
  	    __put_user(s.totalram, &info->totalram) ||
  	    __put_user(s.freeram, &info->freeram) ||
  	    __put_user(s.sharedram, &info->sharedram) ||
  	    __put_user(s.bufferram, &info->bufferram) ||
  	    __put_user(s.totalswap, &info->totalswap) ||
  	    __put_user(s.freeswap, &info->freeswap) ||
  	    __put_user(s.procs, &info->procs) ||
  	    __put_user(s.totalhigh, &info->totalhigh) ||
  	    __put_user(s.freehigh, &info->freehigh) ||
  	    __put_user(s.mem_unit, &info->mem_unit))
  		return -EFAULT;
  
  	return 0;
  }
  #endif /* CONFIG_COMPAT */
  