xref: /openbmc/linux/kernel/sys.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
1 /*
2  *  linux/kernel/sys.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6 
7 #include <linux/module.h>
8 #include <linux/mm.h>
9 #include <linux/utsname.h>
10 #include <linux/mman.h>
11 #include <linux/notifier.h>
12 #include <linux/reboot.h>
13 #include <linux/prctl.h>
14 #include <linux/highuid.h>
15 #include <linux/fs.h>
16 #include <linux/perf_event.h>
17 #include <linux/resource.h>
18 #include <linux/kernel.h>
19 #include <linux/kexec.h>
20 #include <linux/workqueue.h>
21 #include <linux/capability.h>
22 #include <linux/device.h>
23 #include <linux/key.h>
24 #include <linux/times.h>
25 #include <linux/posix-timers.h>
26 #include <linux/security.h>
27 #include <linux/dcookies.h>
28 #include <linux/suspend.h>
29 #include <linux/tty.h>
30 #include <linux/signal.h>
31 #include <linux/cn_proc.h>
32 #include <linux/getcpu.h>
33 #include <linux/task_io_accounting_ops.h>
34 #include <linux/seccomp.h>
35 #include <linux/cpu.h>
36 #include <linux/ptrace.h>
37 #include <linux/fs_struct.h>
38 
39 #include <linux/compat.h>
40 #include <linux/syscalls.h>
41 #include <linux/kprobes.h>
42 #include <linux/user_namespace.h>
43 
44 #include <asm/uaccess.h>
45 #include <asm/io.h>
46 #include <asm/unistd.h>
47 
48 #ifndef SET_UNALIGN_CTL
49 # define SET_UNALIGN_CTL(a,b)	(-EINVAL)
50 #endif
51 #ifndef GET_UNALIGN_CTL
52 # define GET_UNALIGN_CTL(a,b)	(-EINVAL)
53 #endif
54 #ifndef SET_FPEMU_CTL
55 # define SET_FPEMU_CTL(a,b)	(-EINVAL)
56 #endif
57 #ifndef GET_FPEMU_CTL
58 # define GET_FPEMU_CTL(a,b)	(-EINVAL)
59 #endif
60 #ifndef SET_FPEXC_CTL
61 # define SET_FPEXC_CTL(a,b)	(-EINVAL)
62 #endif
63 #ifndef GET_FPEXC_CTL
64 # define GET_FPEXC_CTL(a,b)	(-EINVAL)
65 #endif
66 #ifndef GET_ENDIAN
67 # define GET_ENDIAN(a,b)	(-EINVAL)
68 #endif
69 #ifndef SET_ENDIAN
70 # define SET_ENDIAN(a,b)	(-EINVAL)
71 #endif
72 #ifndef GET_TSC_CTL
73 # define GET_TSC_CTL(a)		(-EINVAL)
74 #endif
75 #ifndef SET_TSC_CTL
76 # define SET_TSC_CTL(a)		(-EINVAL)
77 #endif
78 
79 /*
80  * this is where the system-wide overflow UID and GID are defined, for
81  * architectures that now have 32-bit UID/GID but didn't in the past
82  */
83 
84 int overflowuid = DEFAULT_OVERFLOWUID;
85 int overflowgid = DEFAULT_OVERFLOWGID;
86 
87 #ifdef CONFIG_UID16
88 EXPORT_SYMBOL(overflowuid);
89 EXPORT_SYMBOL(overflowgid);
90 #endif
91 
92 /*
93  * the same as above, but for filesystems which can only store a 16-bit
94  * UID and GID. as such, this is needed on all architectures
95  */
96 
97 int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
98 int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
99 
100 EXPORT_SYMBOL(fs_overflowuid);
101 EXPORT_SYMBOL(fs_overflowgid);
102 
103 /*
104  * this indicates whether you can reboot with ctrl-alt-del: the default is yes
105  */
106 
107 int C_A_D = 1;
108 struct pid *cad_pid;
109 EXPORT_SYMBOL(cad_pid);
110 
111 /*
112  * If set, this is used for preparing the system to power off.
113  */
114 
115 void (*pm_power_off_prepare)(void);
116 
117 /*
118  * set the priority of a task
119  * - the caller must hold the RCU read lock
120  */
121 static int set_one_prio(struct task_struct *p, int niceval, int error)
122 {
123 	const struct cred *cred = current_cred(), *pcred = __task_cred(p);
124 	int no_nice;
125 
126 	if (pcred->uid  != cred->euid &&
127 	    pcred->euid != cred->euid && !capable(CAP_SYS_NICE)) {
128 		error = -EPERM;
129 		goto out;
130 	}
131 	if (niceval < task_nice(p) && !can_nice(p, niceval)) {
132 		error = -EACCES;
133 		goto out;
134 	}
135 	no_nice = security_task_setnice(p, niceval);
136 	if (no_nice) {
137 		error = no_nice;
138 		goto out;
139 	}
140 	if (error == -ESRCH)
141 		error = 0;
142 	set_user_nice(p, niceval);
143 out:
144 	return error;
145 }
146 
147 SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
148 {
149 	struct task_struct *g, *p;
150 	struct user_struct *user;
151 	const struct cred *cred = current_cred();
152 	int error = -EINVAL;
153 	struct pid *pgrp;
154 
155 	if (which > PRIO_USER || which < PRIO_PROCESS)
156 		goto out;
157 
158 	/* normalize: avoid signed division (rounding problems) */
159 	error = -ESRCH;
160 	if (niceval < -20)
161 		niceval = -20;
162 	if (niceval > 19)
163 		niceval = 19;
164 
165 	rcu_read_lock();
166 	read_lock(&tasklist_lock);
167 	switch (which) {
168 		case PRIO_PROCESS:
169 			if (who)
170 				p = find_task_by_vpid(who);
171 			else
172 				p = current;
173 			if (p)
174 				error = set_one_prio(p, niceval, error);
175 			break;
176 		case PRIO_PGRP:
177 			if (who)
178 				pgrp = find_vpid(who);
179 			else
180 				pgrp = task_pgrp(current);
181 			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
182 				error = set_one_prio(p, niceval, error);
183 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
184 			break;
185 		case PRIO_USER:
186 			user = (struct user_struct *) cred->user;
187 			if (!who)
188 				who = cred->uid;
189 			else if ((who != cred->uid) &&
190 				 !(user = find_user(who)))
191 				goto out_unlock;	/* No processes for this user */
192 
193 			do_each_thread(g, p) {
194 				if (__task_cred(p)->uid == who)
195 					error = set_one_prio(p, niceval, error);
196 			} while_each_thread(g, p);
197 			if (who != cred->uid)
198 				free_uid(user);		/* For find_user() */
199 			break;
200 	}
201 out_unlock:
202 	read_unlock(&tasklist_lock);
203 	rcu_read_unlock();
204 out:
205 	return error;
206 }
207 
208 /*
209  * Ugh. To avoid negative return values, "getpriority()" will
210  * not return the normal nice-value, but a negated value that
211  * has been offset by 20 (ie it returns 40..1 instead of -20..19)
212  * to stay compatible.
213  */
214 SYSCALL_DEFINE2(getpriority, int, which, int, who)
215 {
216 	struct task_struct *g, *p;
217 	struct user_struct *user;
218 	const struct cred *cred = current_cred();
219 	long niceval, retval = -ESRCH;
220 	struct pid *pgrp;
221 
222 	if (which > PRIO_USER || which < PRIO_PROCESS)
223 		return -EINVAL;
224 
225 	read_lock(&tasklist_lock);
226 	switch (which) {
227 		case PRIO_PROCESS:
228 			if (who)
229 				p = find_task_by_vpid(who);
230 			else
231 				p = current;
232 			if (p) {
233 				niceval = 20 - task_nice(p);
234 				if (niceval > retval)
235 					retval = niceval;
236 			}
237 			break;
238 		case PRIO_PGRP:
239 			if (who)
240 				pgrp = find_vpid(who);
241 			else
242 				pgrp = task_pgrp(current);
243 			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
244 				niceval = 20 - task_nice(p);
245 				if (niceval > retval)
246 					retval = niceval;
247 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
248 			break;
249 		case PRIO_USER:
250 			user = (struct user_struct *) cred->user;
251 			if (!who)
252 				who = cred->uid;
253 			else if ((who != cred->uid) &&
254 				 !(user = find_user(who)))
255 				goto out_unlock;	/* No processes for this user */
256 
257 			do_each_thread(g, p) {
258 				if (__task_cred(p)->uid == who) {
259 					niceval = 20 - task_nice(p);
260 					if (niceval > retval)
261 						retval = niceval;
262 				}
263 			} while_each_thread(g, p);
264 			if (who != cred->uid)
265 				free_uid(user);		/* for find_user() */
266 			break;
267 	}
268 out_unlock:
269 	read_unlock(&tasklist_lock);
270 
271 	return retval;
272 }
273 
274 /**
275  *	emergency_restart - reboot the system
276  *
277  *	Without shutting down any hardware or taking any locks
278  *	reboot the system.  This is called when we know we are in
279  *	trouble so this is our best effort to reboot.  This is
280  *	safe to call in interrupt context.
281  */
282 void emergency_restart(void)
283 {
284 	machine_emergency_restart();
285 }
286 EXPORT_SYMBOL_GPL(emergency_restart);
287 
288 void kernel_restart_prepare(char *cmd)
289 {
290 	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
291 	system_state = SYSTEM_RESTART;
292 	device_shutdown();
293 	sysdev_shutdown();
294 }
295 
296 /**
297  *	kernel_restart - reboot the system
298  *	@cmd: pointer to buffer containing command to execute for restart
299  *		or %NULL
300  *
301  *	Shutdown everything and perform a clean reboot.
302  *	This is not safe to call in interrupt context.
303  */
304 void kernel_restart(char *cmd)
305 {
306 	kernel_restart_prepare(cmd);
307 	if (!cmd)
308 		printk(KERN_EMERG "Restarting system.\n");
309 	else
310 		printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
311 	machine_restart(cmd);
312 }
313 EXPORT_SYMBOL_GPL(kernel_restart);
314 
315 static void kernel_shutdown_prepare(enum system_states state)
316 {
317 	blocking_notifier_call_chain(&reboot_notifier_list,
318 		(state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
319 	system_state = state;
320 	device_shutdown();
321 }
322 /**
323  *	kernel_halt - halt the system
324  *
325  *	Shutdown everything and perform a clean system halt.
326  */
327 void kernel_halt(void)
328 {
329 	kernel_shutdown_prepare(SYSTEM_HALT);
330 	sysdev_shutdown();
331 	printk(KERN_EMERG "System halted.\n");
332 	machine_halt();
333 }
334 
335 EXPORT_SYMBOL_GPL(kernel_halt);
336 
337 /**
338  *	kernel_power_off - power_off the system
339  *
340  *	Shutdown everything and perform a clean system power_off.
341  */
342 void kernel_power_off(void)
343 {
344 	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
345 	if (pm_power_off_prepare)
346 		pm_power_off_prepare();
347 	disable_nonboot_cpus();
348 	sysdev_shutdown();
349 	printk(KERN_EMERG "Power down.\n");
350 	machine_power_off();
351 }
352 EXPORT_SYMBOL_GPL(kernel_power_off);
353 
354 static DEFINE_MUTEX(reboot_mutex);
355 
356 /*
357  * Reboot system call: for obvious reasons only root may call it,
358  * and even root needs to set up some magic numbers in the registers
359  * so that some mistake won't make this reboot the whole machine.
360  * You can also set the meaning of the ctrl-alt-del-key here.
361  *
362  * reboot doesn't sync: do that yourself before calling this.
363  */
364 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
365 		void __user *, arg)
366 {
367 	char buffer[256];
368 	int ret = 0;
369 
370 	/* We only trust the superuser with rebooting the system. */
371 	if (!capable(CAP_SYS_BOOT))
372 		return -EPERM;
373 
374 	/* For safety, we require "magic" arguments. */
375 	if (magic1 != LINUX_REBOOT_MAGIC1 ||
376 	    (magic2 != LINUX_REBOOT_MAGIC2 &&
377 	                magic2 != LINUX_REBOOT_MAGIC2A &&
378 			magic2 != LINUX_REBOOT_MAGIC2B &&
379 	                magic2 != LINUX_REBOOT_MAGIC2C))
380 		return -EINVAL;
381 
382 	/* Instead of trying to make the power_off code look like
383 	 * halt when pm_power_off is not set do it the easy way.
384 	 */
385 	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
386 		cmd = LINUX_REBOOT_CMD_HALT;
387 
388 	mutex_lock(&reboot_mutex);
389 	switch (cmd) {
390 	case LINUX_REBOOT_CMD_RESTART:
391 		kernel_restart(NULL);
392 		break;
393 
394 	case LINUX_REBOOT_CMD_CAD_ON:
395 		C_A_D = 1;
396 		break;
397 
398 	case LINUX_REBOOT_CMD_CAD_OFF:
399 		C_A_D = 0;
400 		break;
401 
402 	case LINUX_REBOOT_CMD_HALT:
403 		kernel_halt();
404 		do_exit(0);
405 		panic("cannot halt");
406 
407 	case LINUX_REBOOT_CMD_POWER_OFF:
408 		kernel_power_off();
409 		do_exit(0);
410 		break;
411 
412 	case LINUX_REBOOT_CMD_RESTART2:
413 		if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
414 			ret = -EFAULT;
415 			break;
416 		}
417 		buffer[sizeof(buffer) - 1] = '\0';
418 
419 		kernel_restart(buffer);
420 		break;
421 
422 #ifdef CONFIG_KEXEC
423 	case LINUX_REBOOT_CMD_KEXEC:
424 		ret = kernel_kexec();
425 		break;
426 #endif
427 
428 #ifdef CONFIG_HIBERNATION
429 	case LINUX_REBOOT_CMD_SW_SUSPEND:
430 		ret = hibernate();
431 		break;
432 #endif
433 
434 	default:
435 		ret = -EINVAL;
436 		break;
437 	}
438 	mutex_unlock(&reboot_mutex);
439 	return ret;
440 }
441 
442 static void deferred_cad(struct work_struct *dummy)
443 {
444 	kernel_restart(NULL);
445 }
446 
447 /*
448  * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
449  * As it's called within an interrupt, it may NOT sync: the only choice
450  * is whether to reboot at once, or just ignore the ctrl-alt-del.
451  */
452 void ctrl_alt_del(void)
453 {
454 	static DECLARE_WORK(cad_work, deferred_cad);
455 
456 	if (C_A_D)
457 		schedule_work(&cad_work);
458 	else
459 		kill_cad_pid(SIGINT, 1);
460 }
461 
462 /*
463  * Unprivileged users may change the real gid to the effective gid
464  * or vice versa.  (BSD-style)
465  *
466  * If you set the real gid at all, or set the effective gid to a value not
467  * equal to the real gid, then the saved gid is set to the new effective gid.
468  *
469  * This makes it possible for a setgid program to completely drop its
470  * privileges, which is often a useful assertion to make when you are doing
471  * a security audit over a program.
472  *
473  * The general idea is that a program which uses just setregid() will be
474  * 100% compatible with BSD.  A program which uses just setgid() will be
475  * 100% compatible with POSIX with saved IDs.
476  *
477  * SMP: There are not races, the GIDs are checked only by filesystem
478  *      operations (as far as semantic preservation is concerned).
479  */
480 SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
481 {
482 	const struct cred *old;
483 	struct cred *new;
484 	int retval;
485 
486 	new = prepare_creds();
487 	if (!new)
488 		return -ENOMEM;
489 	old = current_cred();
490 
491 	retval = security_task_setgid(rgid, egid, (gid_t)-1, LSM_SETID_RE);
492 	if (retval)
493 		goto error;
494 
495 	retval = -EPERM;
496 	if (rgid != (gid_t) -1) {
497 		if (old->gid == rgid ||
498 		    old->egid == rgid ||
499 		    capable(CAP_SETGID))
500 			new->gid = rgid;
501 		else
502 			goto error;
503 	}
504 	if (egid != (gid_t) -1) {
505 		if (old->gid == egid ||
506 		    old->egid == egid ||
507 		    old->sgid == egid ||
508 		    capable(CAP_SETGID))
509 			new->egid = egid;
510 		else
511 			goto error;
512 	}
513 
514 	if (rgid != (gid_t) -1 ||
515 	    (egid != (gid_t) -1 && egid != old->gid))
516 		new->sgid = new->egid;
517 	new->fsgid = new->egid;
518 
519 	return commit_creds(new);
520 
521 error:
522 	abort_creds(new);
523 	return retval;
524 }
525 
526 /*
527  * setgid() is implemented like SysV w/ SAVED_IDS
528  *
529  * SMP: Same implicit races as above.
530  */
531 SYSCALL_DEFINE1(setgid, gid_t, gid)
532 {
533 	const struct cred *old;
534 	struct cred *new;
535 	int retval;
536 
537 	new = prepare_creds();
538 	if (!new)
539 		return -ENOMEM;
540 	old = current_cred();
541 
542 	retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_ID);
543 	if (retval)
544 		goto error;
545 
546 	retval = -EPERM;
547 	if (capable(CAP_SETGID))
548 		new->gid = new->egid = new->sgid = new->fsgid = gid;
549 	else if (gid == old->gid || gid == old->sgid)
550 		new->egid = new->fsgid = gid;
551 	else
552 		goto error;
553 
554 	return commit_creds(new);
555 
556 error:
557 	abort_creds(new);
558 	return retval;
559 }
560 
561 /*
562  * change the user struct in a credentials set to match the new UID
563  */
564 static int set_user(struct cred *new)
565 {
566 	struct user_struct *new_user;
567 
568 	new_user = alloc_uid(current_user_ns(), new->uid);
569 	if (!new_user)
570 		return -EAGAIN;
571 
572 	if (!task_can_switch_user(new_user, current)) {
573 		free_uid(new_user);
574 		return -EINVAL;
575 	}
576 
577 	if (atomic_read(&new_user->processes) >=
578 				current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
579 			new_user != INIT_USER) {
580 		free_uid(new_user);
581 		return -EAGAIN;
582 	}
583 
584 	free_uid(new->user);
585 	new->user = new_user;
586 	return 0;
587 }
588 
589 /*
590  * Unprivileged users may change the real uid to the effective uid
591  * or vice versa.  (BSD-style)
592  *
593  * If you set the real uid at all, or set the effective uid to a value not
594  * equal to the real uid, then the saved uid is set to the new effective uid.
595  *
596  * This makes it possible for a setuid program to completely drop its
597  * privileges, which is often a useful assertion to make when you are doing
598  * a security audit over a program.
599  *
600  * The general idea is that a program which uses just setreuid() will be
601  * 100% compatible with BSD.  A program which uses just setuid() will be
602  * 100% compatible with POSIX with saved IDs.
603  */
604 SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
605 {
606 	const struct cred *old;
607 	struct cred *new;
608 	int retval;
609 
610 	new = prepare_creds();
611 	if (!new)
612 		return -ENOMEM;
613 	old = current_cred();
614 
615 	retval = security_task_setuid(ruid, euid, (uid_t)-1, LSM_SETID_RE);
616 	if (retval)
617 		goto error;
618 
619 	retval = -EPERM;
620 	if (ruid != (uid_t) -1) {
621 		new->uid = ruid;
622 		if (old->uid != ruid &&
623 		    old->euid != ruid &&
624 		    !capable(CAP_SETUID))
625 			goto error;
626 	}
627 
628 	if (euid != (uid_t) -1) {
629 		new->euid = euid;
630 		if (old->uid != euid &&
631 		    old->euid != euid &&
632 		    old->suid != euid &&
633 		    !capable(CAP_SETUID))
634 			goto error;
635 	}
636 
637 	if (new->uid != old->uid) {
638 		retval = set_user(new);
639 		if (retval < 0)
640 			goto error;
641 	}
642 	if (ruid != (uid_t) -1 ||
643 	    (euid != (uid_t) -1 && euid != old->uid))
644 		new->suid = new->euid;
645 	new->fsuid = new->euid;
646 
647 	retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
648 	if (retval < 0)
649 		goto error;
650 
651 	return commit_creds(new);
652 
653 error:
654 	abort_creds(new);
655 	return retval;
656 }
657 
658 /*
659  * setuid() is implemented like SysV with SAVED_IDS
660  *
661  * Note that SAVED_ID's is deficient in that a setuid root program
662  * like sendmail, for example, cannot set its uid to be a normal
663  * user and then switch back, because if you're root, setuid() sets
664  * the saved uid too.  If you don't like this, blame the bright people
665  * in the POSIX committee and/or USG.  Note that the BSD-style setreuid()
666  * will allow a root program to temporarily drop privileges and be able to
667  * regain them by swapping the real and effective uid.
668  */
669 SYSCALL_DEFINE1(setuid, uid_t, uid)
670 {
671 	const struct cred *old;
672 	struct cred *new;
673 	int retval;
674 
675 	new = prepare_creds();
676 	if (!new)
677 		return -ENOMEM;
678 	old = current_cred();
679 
680 	retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_ID);
681 	if (retval)
682 		goto error;
683 
684 	retval = -EPERM;
685 	if (capable(CAP_SETUID)) {
686 		new->suid = new->uid = uid;
687 		if (uid != old->uid) {
688 			retval = set_user(new);
689 			if (retval < 0)
690 				goto error;
691 		}
692 	} else if (uid != old->uid && uid != new->suid) {
693 		goto error;
694 	}
695 
696 	new->fsuid = new->euid = uid;
697 
698 	retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
699 	if (retval < 0)
700 		goto error;
701 
702 	return commit_creds(new);
703 
704 error:
705 	abort_creds(new);
706 	return retval;
707 }
708 
709 
710 /*
711  * This function implements a generic ability to update ruid, euid,
712  * and suid.  This allows you to implement the 4.4 compatible seteuid().
713  */
714 SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
715 {
716 	const struct cred *old;
717 	struct cred *new;
718 	int retval;
719 
720 	new = prepare_creds();
721 	if (!new)
722 		return -ENOMEM;
723 
724 	retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES);
725 	if (retval)
726 		goto error;
727 	old = current_cred();
728 
729 	retval = -EPERM;
730 	if (!capable(CAP_SETUID)) {
731 		if (ruid != (uid_t) -1 && ruid != old->uid &&
732 		    ruid != old->euid  && ruid != old->suid)
733 			goto error;
734 		if (euid != (uid_t) -1 && euid != old->uid &&
735 		    euid != old->euid  && euid != old->suid)
736 			goto error;
737 		if (suid != (uid_t) -1 && suid != old->uid &&
738 		    suid != old->euid  && suid != old->suid)
739 			goto error;
740 	}
741 
742 	if (ruid != (uid_t) -1) {
743 		new->uid = ruid;
744 		if (ruid != old->uid) {
745 			retval = set_user(new);
746 			if (retval < 0)
747 				goto error;
748 		}
749 	}
750 	if (euid != (uid_t) -1)
751 		new->euid = euid;
752 	if (suid != (uid_t) -1)
753 		new->suid = suid;
754 	new->fsuid = new->euid;
755 
756 	retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
757 	if (retval < 0)
758 		goto error;
759 
760 	return commit_creds(new);
761 
762 error:
763 	abort_creds(new);
764 	return retval;
765 }
766 
767 SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __user *, suid)
768 {
769 	const struct cred *cred = current_cred();
770 	int retval;
771 
772 	if (!(retval   = put_user(cred->uid,  ruid)) &&
773 	    !(retval   = put_user(cred->euid, euid)))
774 		retval = put_user(cred->suid, suid);
775 
776 	return retval;
777 }
778 
779 /*
780  * Same as above, but for rgid, egid, sgid.
781  */
782 SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
783 {
784 	const struct cred *old;
785 	struct cred *new;
786 	int retval;
787 
788 	new = prepare_creds();
789 	if (!new)
790 		return -ENOMEM;
791 	old = current_cred();
792 
793 	retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES);
794 	if (retval)
795 		goto error;
796 
797 	retval = -EPERM;
798 	if (!capable(CAP_SETGID)) {
799 		if (rgid != (gid_t) -1 && rgid != old->gid &&
800 		    rgid != old->egid  && rgid != old->sgid)
801 			goto error;
802 		if (egid != (gid_t) -1 && egid != old->gid &&
803 		    egid != old->egid  && egid != old->sgid)
804 			goto error;
805 		if (sgid != (gid_t) -1 && sgid != old->gid &&
806 		    sgid != old->egid  && sgid != old->sgid)
807 			goto error;
808 	}
809 
810 	if (rgid != (gid_t) -1)
811 		new->gid = rgid;
812 	if (egid != (gid_t) -1)
813 		new->egid = egid;
814 	if (sgid != (gid_t) -1)
815 		new->sgid = sgid;
816 	new->fsgid = new->egid;
817 
818 	return commit_creds(new);
819 
820 error:
821 	abort_creds(new);
822 	return retval;
823 }
824 
825 SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __user *, sgid)
826 {
827 	const struct cred *cred = current_cred();
828 	int retval;
829 
830 	if (!(retval   = put_user(cred->gid,  rgid)) &&
831 	    !(retval   = put_user(cred->egid, egid)))
832 		retval = put_user(cred->sgid, sgid);
833 
834 	return retval;
835 }
836 
837 
838 /*
839  * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
840  * is used for "access()" and for the NFS daemon (letting nfsd stay at
841  * whatever uid it wants to). It normally shadows "euid", except when
842  * explicitly set by setfsuid() or for access..
843  */
844 SYSCALL_DEFINE1(setfsuid, uid_t, uid)
845 {
846 	const struct cred *old;
847 	struct cred *new;
848 	uid_t old_fsuid;
849 
850 	new = prepare_creds();
851 	if (!new)
852 		return current_fsuid();
853 	old = current_cred();
854 	old_fsuid = old->fsuid;
855 
856 	if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS) < 0)
857 		goto error;
858 
859 	if (uid == old->uid  || uid == old->euid  ||
860 	    uid == old->suid || uid == old->fsuid ||
861 	    capable(CAP_SETUID)) {
862 		if (uid != old_fsuid) {
863 			new->fsuid = uid;
864 			if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
865 				goto change_okay;
866 		}
867 	}
868 
869 error:
870 	abort_creds(new);
871 	return old_fsuid;
872 
873 change_okay:
874 	commit_creds(new);
875 	return old_fsuid;
876 }
877 
878 /*
879  * Samma pÃ¥ svenska..
880  */
881 SYSCALL_DEFINE1(setfsgid, gid_t, gid)
882 {
883 	const struct cred *old;
884 	struct cred *new;
885 	gid_t old_fsgid;
886 
887 	new = prepare_creds();
888 	if (!new)
889 		return current_fsgid();
890 	old = current_cred();
891 	old_fsgid = old->fsgid;
892 
893 	if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS))
894 		goto error;
895 
896 	if (gid == old->gid  || gid == old->egid  ||
897 	    gid == old->sgid || gid == old->fsgid ||
898 	    capable(CAP_SETGID)) {
899 		if (gid != old_fsgid) {
900 			new->fsgid = gid;
901 			goto change_okay;
902 		}
903 	}
904 
905 error:
906 	abort_creds(new);
907 	return old_fsgid;
908 
909 change_okay:
910 	commit_creds(new);
911 	return old_fsgid;
912 }
913 
914 void do_sys_times(struct tms *tms)
915 {
916 	cputime_t tgutime, tgstime, cutime, cstime;
917 
918 	spin_lock_irq(&current->sighand->siglock);
919 	thread_group_times(current, &tgutime, &tgstime);
920 	cutime = current->signal->cutime;
921 	cstime = current->signal->cstime;
922 	spin_unlock_irq(&current->sighand->siglock);
923 	tms->tms_utime = cputime_to_clock_t(tgutime);
924 	tms->tms_stime = cputime_to_clock_t(tgstime);
925 	tms->tms_cutime = cputime_to_clock_t(cutime);
926 	tms->tms_cstime = cputime_to_clock_t(cstime);
927 }
928 
929 SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
930 {
931 	if (tbuf) {
932 		struct tms tmp;
933 
934 		do_sys_times(&tmp);
935 		if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
936 			return -EFAULT;
937 	}
938 	force_successful_syscall_return();
939 	return (long) jiffies_64_to_clock_t(get_jiffies_64());
940 }
941 
942 /*
943  * This needs some heavy checking ...
944  * I just haven't the stomach for it. I also don't fully
945  * understand sessions/pgrp etc. Let somebody who does explain it.
946  *
947  * OK, I think I have the protection semantics right.... this is really
948  * only important on a multi-user system anyway, to make sure one user
949  * can't send a signal to a process owned by another.  -TYT, 12/12/91
950  *
951  * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
952  * LBT 04.03.94
953  */
954 SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
955 {
956 	struct task_struct *p;
957 	struct task_struct *group_leader = current->group_leader;
958 	struct pid *pgrp;
959 	int err;
960 
961 	if (!pid)
962 		pid = task_pid_vnr(group_leader);
963 	if (!pgid)
964 		pgid = pid;
965 	if (pgid < 0)
966 		return -EINVAL;
967 
968 	/* From this point forward we keep holding onto the tasklist lock
969 	 * so that our parent does not change from under us. -DaveM
970 	 */
971 	write_lock_irq(&tasklist_lock);
972 
973 	err = -ESRCH;
974 	p = find_task_by_vpid(pid);
975 	if (!p)
976 		goto out;
977 
978 	err = -EINVAL;
979 	if (!thread_group_leader(p))
980 		goto out;
981 
982 	if (same_thread_group(p->real_parent, group_leader)) {
983 		err = -EPERM;
984 		if (task_session(p) != task_session(group_leader))
985 			goto out;
986 		err = -EACCES;
987 		if (p->did_exec)
988 			goto out;
989 	} else {
990 		err = -ESRCH;
991 		if (p != group_leader)
992 			goto out;
993 	}
994 
995 	err = -EPERM;
996 	if (p->signal->leader)
997 		goto out;
998 
999 	pgrp = task_pid(p);
1000 	if (pgid != pid) {
1001 		struct task_struct *g;
1002 
1003 		pgrp = find_vpid(pgid);
1004 		g = pid_task(pgrp, PIDTYPE_PGID);
1005 		if (!g || task_session(g) != task_session(group_leader))
1006 			goto out;
1007 	}
1008 
1009 	err = security_task_setpgid(p, pgid);
1010 	if (err)
1011 		goto out;
1012 
1013 	if (task_pgrp(p) != pgrp)
1014 		change_pid(p, PIDTYPE_PGID, pgrp);
1015 
1016 	err = 0;
1017 out:
1018 	/* All paths lead to here, thus we are safe. -DaveM */
1019 	write_unlock_irq(&tasklist_lock);
1020 	return err;
1021 }
1022 
1023 SYSCALL_DEFINE1(getpgid, pid_t, pid)
1024 {
1025 	struct task_struct *p;
1026 	struct pid *grp;
1027 	int retval;
1028 
1029 	rcu_read_lock();
1030 	if (!pid)
1031 		grp = task_pgrp(current);
1032 	else {
1033 		retval = -ESRCH;
1034 		p = find_task_by_vpid(pid);
1035 		if (!p)
1036 			goto out;
1037 		grp = task_pgrp(p);
1038 		if (!grp)
1039 			goto out;
1040 
1041 		retval = security_task_getpgid(p);
1042 		if (retval)
1043 			goto out;
1044 	}
1045 	retval = pid_vnr(grp);
1046 out:
1047 	rcu_read_unlock();
1048 	return retval;
1049 }
1050 
1051 #ifdef __ARCH_WANT_SYS_GETPGRP
1052 
1053 SYSCALL_DEFINE0(getpgrp)
1054 {
1055 	return sys_getpgid(0);
1056 }
1057 
1058 #endif
1059 
1060 SYSCALL_DEFINE1(getsid, pid_t, pid)
1061 {
1062 	struct task_struct *p;
1063 	struct pid *sid;
1064 	int retval;
1065 
1066 	rcu_read_lock();
1067 	if (!pid)
1068 		sid = task_session(current);
1069 	else {
1070 		retval = -ESRCH;
1071 		p = find_task_by_vpid(pid);
1072 		if (!p)
1073 			goto out;
1074 		sid = task_session(p);
1075 		if (!sid)
1076 			goto out;
1077 
1078 		retval = security_task_getsid(p);
1079 		if (retval)
1080 			goto out;
1081 	}
1082 	retval = pid_vnr(sid);
1083 out:
1084 	rcu_read_unlock();
1085 	return retval;
1086 }
1087 
1088 SYSCALL_DEFINE0(setsid)
1089 {
1090 	struct task_struct *group_leader = current->group_leader;
1091 	struct pid *sid = task_pid(group_leader);
1092 	pid_t session = pid_vnr(sid);
1093 	int err = -EPERM;
1094 
1095 	write_lock_irq(&tasklist_lock);
1096 	/* Fail if I am already a session leader */
1097 	if (group_leader->signal->leader)
1098 		goto out;
1099 
1100 	/* Fail if a process group id already exists that equals the
1101 	 * proposed session id.
1102 	 */
1103 	if (pid_task(sid, PIDTYPE_PGID))
1104 		goto out;
1105 
1106 	group_leader->signal->leader = 1;
1107 	__set_special_pids(sid);
1108 
1109 	proc_clear_tty(group_leader);
1110 
1111 	err = session;
1112 out:
1113 	write_unlock_irq(&tasklist_lock);
1114 	if (err > 0)
1115 		proc_sid_connector(group_leader);
1116 	return err;
1117 }
1118 
1119 DECLARE_RWSEM(uts_sem);
1120 
1121 SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
1122 {
1123 	int errno = 0;
1124 
1125 	down_read(&uts_sem);
1126 	if (copy_to_user(name, utsname(), sizeof *name))
1127 		errno = -EFAULT;
1128 	up_read(&uts_sem);
1129 	return errno;
1130 }
1131 
1132 SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
1133 {
1134 	int errno;
1135 	char tmp[__NEW_UTS_LEN];
1136 
1137 	if (!capable(CAP_SYS_ADMIN))
1138 		return -EPERM;
1139 	if (len < 0 || len > __NEW_UTS_LEN)
1140 		return -EINVAL;
1141 	down_write(&uts_sem);
1142 	errno = -EFAULT;
1143 	if (!copy_from_user(tmp, name, len)) {
1144 		struct new_utsname *u = utsname();
1145 
1146 		memcpy(u->nodename, tmp, len);
1147 		memset(u->nodename + len, 0, sizeof(u->nodename) - len);
1148 		errno = 0;
1149 	}
1150 	up_write(&uts_sem);
1151 	return errno;
1152 }
1153 
1154 #ifdef __ARCH_WANT_SYS_GETHOSTNAME
1155 
1156 SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
1157 {
1158 	int i, errno;
1159 	struct new_utsname *u;
1160 
1161 	if (len < 0)
1162 		return -EINVAL;
1163 	down_read(&uts_sem);
1164 	u = utsname();
1165 	i = 1 + strlen(u->nodename);
1166 	if (i > len)
1167 		i = len;
1168 	errno = 0;
1169 	if (copy_to_user(name, u->nodename, i))
1170 		errno = -EFAULT;
1171 	up_read(&uts_sem);
1172 	return errno;
1173 }
1174 
1175 #endif
1176 
1177 /*
1178  * Only setdomainname; getdomainname can be implemented by calling
1179  * uname()
1180  */
1181 SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
1182 {
1183 	int errno;
1184 	char tmp[__NEW_UTS_LEN];
1185 
1186 	if (!capable(CAP_SYS_ADMIN))
1187 		return -EPERM;
1188 	if (len < 0 || len > __NEW_UTS_LEN)
1189 		return -EINVAL;
1190 
1191 	down_write(&uts_sem);
1192 	errno = -EFAULT;
1193 	if (!copy_from_user(tmp, name, len)) {
1194 		struct new_utsname *u = utsname();
1195 
1196 		memcpy(u->domainname, tmp, len);
1197 		memset(u->domainname + len, 0, sizeof(u->domainname) - len);
1198 		errno = 0;
1199 	}
1200 	up_write(&uts_sem);
1201 	return errno;
1202 }
1203 
1204 SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1205 {
1206 	if (resource >= RLIM_NLIMITS)
1207 		return -EINVAL;
1208 	else {
1209 		struct rlimit value;
1210 		task_lock(current->group_leader);
1211 		value = current->signal->rlim[resource];
1212 		task_unlock(current->group_leader);
1213 		return copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
1214 	}
1215 }
1216 
1217 #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
1218 
1219 /*
1220  *	Back compatibility for getrlimit. Needed for some apps.
1221  */
1222 
1223 SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
1224 		struct rlimit __user *, rlim)
1225 {
1226 	struct rlimit x;
1227 	if (resource >= RLIM_NLIMITS)
1228 		return -EINVAL;
1229 
1230 	task_lock(current->group_leader);
1231 	x = current->signal->rlim[resource];
1232 	task_unlock(current->group_leader);
1233 	if (x.rlim_cur > 0x7FFFFFFF)
1234 		x.rlim_cur = 0x7FFFFFFF;
1235 	if (x.rlim_max > 0x7FFFFFFF)
1236 		x.rlim_max = 0x7FFFFFFF;
1237 	return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
1238 }
1239 
1240 #endif
1241 
1242 SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1243 {
1244 	struct rlimit new_rlim, *old_rlim;
1245 	int retval;
1246 
1247 	if (resource >= RLIM_NLIMITS)
1248 		return -EINVAL;
1249 	if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
1250 		return -EFAULT;
1251 	if (new_rlim.rlim_cur > new_rlim.rlim_max)
1252 		return -EINVAL;
1253 	old_rlim = current->signal->rlim + resource;
1254 	if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
1255 	    !capable(CAP_SYS_RESOURCE))
1256 		return -EPERM;
1257 	if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open)
1258 		return -EPERM;
1259 
1260 	retval = security_task_setrlimit(resource, &new_rlim);
1261 	if (retval)
1262 		return retval;
1263 
1264 	if (resource == RLIMIT_CPU && new_rlim.rlim_cur == 0) {
1265 		/*
1266 		 * The caller is asking for an immediate RLIMIT_CPU
1267 		 * expiry.  But we use the zero value to mean "it was
1268 		 * never set".  So let's cheat and make it one second
1269 		 * instead
1270 		 */
1271 		new_rlim.rlim_cur = 1;
1272 	}
1273 
1274 	task_lock(current->group_leader);
1275 	*old_rlim = new_rlim;
1276 	task_unlock(current->group_leader);
1277 
1278 	if (resource != RLIMIT_CPU)
1279 		goto out;
1280 
1281 	/*
1282 	 * RLIMIT_CPU handling.   Note that the kernel fails to return an error
1283 	 * code if it rejected the user's attempt to set RLIMIT_CPU.  This is a
1284 	 * very long-standing error, and fixing it now risks breakage of
1285 	 * applications, so we live with it
1286 	 */
1287 	if (new_rlim.rlim_cur == RLIM_INFINITY)
1288 		goto out;
1289 
1290 	update_rlimit_cpu(new_rlim.rlim_cur);
1291 out:
1292 	return 0;
1293 }
1294 
1295 /*
1296  * It would make sense to put struct rusage in the task_struct,
1297  * except that would make the task_struct be *really big*.  After
1298  * task_struct gets moved into malloc'ed memory, it would
1299  * make sense to do this.  It will make moving the rest of the information
1300  * a lot simpler!  (Which we're not doing right now because we're not
1301  * measuring them yet).
1302  *
1303  * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
1304  * races with threads incrementing their own counters.  But since word
1305  * reads are atomic, we either get new values or old values and we don't
1306  * care which for the sums.  We always take the siglock to protect reading
1307  * the c* fields from p->signal from races with exit.c updating those
1308  * fields when reaping, so a sample either gets all the additions of a
1309  * given child after it's reaped, or none so this sample is before reaping.
1310  *
1311  * Locking:
1312  * We need to take the siglock for CHILDEREN, SELF and BOTH
1313  * for  the cases current multithreaded, non-current single threaded
1314  * non-current multithreaded.  Thread traversal is now safe with
1315  * the siglock held.
1316  * Strictly speaking, we donot need to take the siglock if we are current and
1317  * single threaded,  as no one else can take our signal_struct away, no one
1318  * else can  reap the  children to update signal->c* counters, and no one else
1319  * can race with the signal-> fields. If we do not take any lock, the
1320  * signal-> fields could be read out of order while another thread was just
1321  * exiting. So we should  place a read memory barrier when we avoid the lock.
1322  * On the writer side,  write memory barrier is implied in  __exit_signal
1323  * as __exit_signal releases  the siglock spinlock after updating the signal->
1324  * fields. But we don't do this yet to keep things simple.
1325  *
1326  */
1327 
1328 static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
1329 {
1330 	r->ru_nvcsw += t->nvcsw;
1331 	r->ru_nivcsw += t->nivcsw;
1332 	r->ru_minflt += t->min_flt;
1333 	r->ru_majflt += t->maj_flt;
1334 	r->ru_inblock += task_io_get_inblock(t);
1335 	r->ru_oublock += task_io_get_oublock(t);
1336 }
1337 
1338 static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
1339 {
1340 	struct task_struct *t;
1341 	unsigned long flags;
1342 	cputime_t tgutime, tgstime, utime, stime;
1343 	unsigned long maxrss = 0;
1344 
1345 	memset((char *) r, 0, sizeof *r);
1346 	utime = stime = cputime_zero;
1347 
1348 	if (who == RUSAGE_THREAD) {
1349 		task_times(current, &utime, &stime);
1350 		accumulate_thread_rusage(p, r);
1351 		maxrss = p->signal->maxrss;
1352 		goto out;
1353 	}
1354 
1355 	if (!lock_task_sighand(p, &flags))
1356 		return;
1357 
1358 	switch (who) {
1359 		case RUSAGE_BOTH:
1360 		case RUSAGE_CHILDREN:
1361 			utime = p->signal->cutime;
1362 			stime = p->signal->cstime;
1363 			r->ru_nvcsw = p->signal->cnvcsw;
1364 			r->ru_nivcsw = p->signal->cnivcsw;
1365 			r->ru_minflt = p->signal->cmin_flt;
1366 			r->ru_majflt = p->signal->cmaj_flt;
1367 			r->ru_inblock = p->signal->cinblock;
1368 			r->ru_oublock = p->signal->coublock;
1369 			maxrss = p->signal->cmaxrss;
1370 
1371 			if (who == RUSAGE_CHILDREN)
1372 				break;
1373 
1374 		case RUSAGE_SELF:
1375 			thread_group_times(p, &tgutime, &tgstime);
1376 			utime = cputime_add(utime, tgutime);
1377 			stime = cputime_add(stime, tgstime);
1378 			r->ru_nvcsw += p->signal->nvcsw;
1379 			r->ru_nivcsw += p->signal->nivcsw;
1380 			r->ru_minflt += p->signal->min_flt;
1381 			r->ru_majflt += p->signal->maj_flt;
1382 			r->ru_inblock += p->signal->inblock;
1383 			r->ru_oublock += p->signal->oublock;
1384 			if (maxrss < p->signal->maxrss)
1385 				maxrss = p->signal->maxrss;
1386 			t = p;
1387 			do {
1388 				accumulate_thread_rusage(t, r);
1389 				t = next_thread(t);
1390 			} while (t != p);
1391 			break;
1392 
1393 		default:
1394 			BUG();
1395 	}
1396 	unlock_task_sighand(p, &flags);
1397 
1398 out:
1399 	cputime_to_timeval(utime, &r->ru_utime);
1400 	cputime_to_timeval(stime, &r->ru_stime);
1401 
1402 	if (who != RUSAGE_CHILDREN) {
1403 		struct mm_struct *mm = get_task_mm(p);
1404 		if (mm) {
1405 			setmax_mm_hiwater_rss(&maxrss, mm);
1406 			mmput(mm);
1407 		}
1408 	}
1409 	r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
1410 }
1411 
1412 int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
1413 {
1414 	struct rusage r;
1415 	k_getrusage(p, who, &r);
1416 	return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
1417 }
1418 
1419 SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
1420 {
1421 	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
1422 	    who != RUSAGE_THREAD)
1423 		return -EINVAL;
1424 	return getrusage(current, who, ru);
1425 }
1426 
1427 SYSCALL_DEFINE1(umask, int, mask)
1428 {
1429 	mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
1430 	return mask;
1431 }
1432 
1433 SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
1434 		unsigned long, arg4, unsigned long, arg5)
1435 {
1436 	struct task_struct *me = current;
1437 	unsigned char comm[sizeof(me->comm)];
1438 	long error;
1439 
1440 	error = security_task_prctl(option, arg2, arg3, arg4, arg5);
1441 	if (error != -ENOSYS)
1442 		return error;
1443 
1444 	error = 0;
1445 	switch (option) {
1446 		case PR_SET_PDEATHSIG:
1447 			if (!valid_signal(arg2)) {
1448 				error = -EINVAL;
1449 				break;
1450 			}
1451 			me->pdeath_signal = arg2;
1452 			error = 0;
1453 			break;
1454 		case PR_GET_PDEATHSIG:
1455 			error = put_user(me->pdeath_signal, (int __user *)arg2);
1456 			break;
1457 		case PR_GET_DUMPABLE:
1458 			error = get_dumpable(me->mm);
1459 			break;
1460 		case PR_SET_DUMPABLE:
1461 			if (arg2 < 0 || arg2 > 1) {
1462 				error = -EINVAL;
1463 				break;
1464 			}
1465 			set_dumpable(me->mm, arg2);
1466 			error = 0;
1467 			break;
1468 
1469 		case PR_SET_UNALIGN:
1470 			error = SET_UNALIGN_CTL(me, arg2);
1471 			break;
1472 		case PR_GET_UNALIGN:
1473 			error = GET_UNALIGN_CTL(me, arg2);
1474 			break;
1475 		case PR_SET_FPEMU:
1476 			error = SET_FPEMU_CTL(me, arg2);
1477 			break;
1478 		case PR_GET_FPEMU:
1479 			error = GET_FPEMU_CTL(me, arg2);
1480 			break;
1481 		case PR_SET_FPEXC:
1482 			error = SET_FPEXC_CTL(me, arg2);
1483 			break;
1484 		case PR_GET_FPEXC:
1485 			error = GET_FPEXC_CTL(me, arg2);
1486 			break;
1487 		case PR_GET_TIMING:
1488 			error = PR_TIMING_STATISTICAL;
1489 			break;
1490 		case PR_SET_TIMING:
1491 			if (arg2 != PR_TIMING_STATISTICAL)
1492 				error = -EINVAL;
1493 			else
1494 				error = 0;
1495 			break;
1496 
1497 		case PR_SET_NAME:
1498 			comm[sizeof(me->comm)-1] = 0;
1499 			if (strncpy_from_user(comm, (char __user *)arg2,
1500 					      sizeof(me->comm) - 1) < 0)
1501 				return -EFAULT;
1502 			set_task_comm(me, comm);
1503 			return 0;
1504 		case PR_GET_NAME:
1505 			get_task_comm(comm, me);
1506 			if (copy_to_user((char __user *)arg2, comm,
1507 					 sizeof(comm)))
1508 				return -EFAULT;
1509 			return 0;
1510 		case PR_GET_ENDIAN:
1511 			error = GET_ENDIAN(me, arg2);
1512 			break;
1513 		case PR_SET_ENDIAN:
1514 			error = SET_ENDIAN(me, arg2);
1515 			break;
1516 
1517 		case PR_GET_SECCOMP:
1518 			error = prctl_get_seccomp();
1519 			break;
1520 		case PR_SET_SECCOMP:
1521 			error = prctl_set_seccomp(arg2);
1522 			break;
1523 		case PR_GET_TSC:
1524 			error = GET_TSC_CTL(arg2);
1525 			break;
1526 		case PR_SET_TSC:
1527 			error = SET_TSC_CTL(arg2);
1528 			break;
1529 		case PR_TASK_PERF_EVENTS_DISABLE:
1530 			error = perf_event_task_disable();
1531 			break;
1532 		case PR_TASK_PERF_EVENTS_ENABLE:
1533 			error = perf_event_task_enable();
1534 			break;
1535 		case PR_GET_TIMERSLACK:
1536 			error = current->timer_slack_ns;
1537 			break;
1538 		case PR_SET_TIMERSLACK:
1539 			if (arg2 <= 0)
1540 				current->timer_slack_ns =
1541 					current->default_timer_slack_ns;
1542 			else
1543 				current->timer_slack_ns = arg2;
1544 			error = 0;
1545 			break;
1546 		case PR_MCE_KILL:
1547 			if (arg4 | arg5)
1548 				return -EINVAL;
1549 			switch (arg2) {
1550 			case PR_MCE_KILL_CLEAR:
1551 				if (arg3 != 0)
1552 					return -EINVAL;
1553 				current->flags &= ~PF_MCE_PROCESS;
1554 				break;
1555 			case PR_MCE_KILL_SET:
1556 				current->flags |= PF_MCE_PROCESS;
1557 				if (arg3 == PR_MCE_KILL_EARLY)
1558 					current->flags |= PF_MCE_EARLY;
1559 				else if (arg3 == PR_MCE_KILL_LATE)
1560 					current->flags &= ~PF_MCE_EARLY;
1561 				else if (arg3 == PR_MCE_KILL_DEFAULT)
1562 					current->flags &=
1563 						~(PF_MCE_EARLY|PF_MCE_PROCESS);
1564 				else
1565 					return -EINVAL;
1566 				break;
1567 			default:
1568 				return -EINVAL;
1569 			}
1570 			error = 0;
1571 			break;
1572 		case PR_MCE_KILL_GET:
1573 			if (arg2 | arg3 | arg4 | arg5)
1574 				return -EINVAL;
1575 			if (current->flags & PF_MCE_PROCESS)
1576 				error = (current->flags & PF_MCE_EARLY) ?
1577 					PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE;
1578 			else
1579 				error = PR_MCE_KILL_DEFAULT;
1580 			break;
1581 		default:
1582 			error = -EINVAL;
1583 			break;
1584 	}
1585 	return error;
1586 }
1587 
1588 SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
1589 		struct getcpu_cache __user *, unused)
1590 {
1591 	int err = 0;
1592 	int cpu = raw_smp_processor_id();
1593 	if (cpup)
1594 		err |= put_user(cpu, cpup);
1595 	if (nodep)
1596 		err |= put_user(cpu_to_node(cpu), nodep);
1597 	return err ? -EFAULT : 0;
1598 }
1599 
1600 char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
1601 
1602 static void argv_cleanup(char **argv, char **envp)
1603 {
1604 	argv_free(argv);
1605 }
1606 
1607 /**
1608  * orderly_poweroff - Trigger an orderly system poweroff
1609  * @force: force poweroff if command execution fails
1610  *
1611  * This may be called from any context to trigger a system shutdown.
1612  * If the orderly shutdown fails, it will force an immediate shutdown.
1613  */
1614 int orderly_poweroff(bool force)
1615 {
1616 	int argc;
1617 	char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
1618 	static char *envp[] = {
1619 		"HOME=/",
1620 		"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
1621 		NULL
1622 	};
1623 	int ret = -ENOMEM;
1624 	struct subprocess_info *info;
1625 
1626 	if (argv == NULL) {
1627 		printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
1628 		       __func__, poweroff_cmd);
1629 		goto out;
1630 	}
1631 
1632 	info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
1633 	if (info == NULL) {
1634 		argv_free(argv);
1635 		goto out;
1636 	}
1637 
1638 	call_usermodehelper_setcleanup(info, argv_cleanup);
1639 
1640 	ret = call_usermodehelper_exec(info, UMH_NO_WAIT);
1641 
1642   out:
1643 	if (ret && force) {
1644 		printk(KERN_WARNING "Failed to start orderly shutdown: "
1645 		       "forcing the issue\n");
1646 
1647 		/* I guess this should try to kick off some daemon to
1648 		   sync and poweroff asap.  Or not even bother syncing
1649 		   if we're doing an emergency shutdown? */
1650 		emergency_sync();
1651 		kernel_power_off();
1652 	}
1653 
1654 	return ret;
1655 }
1656 EXPORT_SYMBOL_GPL(orderly_poweroff);
1657