xref: /openbmc/linux/kernel/ptrace.c (revision e190bfe5)
1 /*
2  * linux/kernel/ptrace.c
3  *
4  * (C) Copyright 1999 Linus Torvalds
5  *
6  * Common interfaces for "ptrace()" which we do not want
7  * to continually duplicate across every architecture.
8  */
9 
10 #include <linux/capability.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/errno.h>
14 #include <linux/mm.h>
15 #include <linux/highmem.h>
16 #include <linux/pagemap.h>
17 #include <linux/ptrace.h>
18 #include <linux/security.h>
19 #include <linux/signal.h>
20 #include <linux/audit.h>
21 #include <linux/pid_namespace.h>
22 #include <linux/syscalls.h>
23 #include <linux/uaccess.h>
24 #include <linux/regset.h>
25 
26 
27 /*
28  * ptrace a task: make the debugger its new parent and
29  * move it to the ptrace list.
30  *
31  * Must be called with the tasklist lock write-held.
32  */
33 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
34 {
35 	BUG_ON(!list_empty(&child->ptrace_entry));
36 	list_add(&child->ptrace_entry, &new_parent->ptraced);
37 	child->parent = new_parent;
38 }
39 
40 /*
41  * Turn a tracing stop into a normal stop now, since with no tracer there
42  * would be no way to wake it up with SIGCONT or SIGKILL.  If there was a
43  * signal sent that would resume the child, but didn't because it was in
44  * TASK_TRACED, resume it now.
45  * Requires that irqs be disabled.
46  */
47 static void ptrace_untrace(struct task_struct *child)
48 {
49 	spin_lock(&child->sighand->siglock);
50 	if (task_is_traced(child)) {
51 		/*
52 		 * If the group stop is completed or in progress,
53 		 * this thread was already counted as stopped.
54 		 */
55 		if (child->signal->flags & SIGNAL_STOP_STOPPED ||
56 		    child->signal->group_stop_count)
57 			__set_task_state(child, TASK_STOPPED);
58 		else
59 			signal_wake_up(child, 1);
60 	}
61 	spin_unlock(&child->sighand->siglock);
62 }
63 
64 /*
65  * unptrace a task: move it back to its original parent and
66  * remove it from the ptrace list.
67  *
68  * Must be called with the tasklist lock write-held.
69  */
70 void __ptrace_unlink(struct task_struct *child)
71 {
72 	BUG_ON(!child->ptrace);
73 
74 	child->ptrace = 0;
75 	child->parent = child->real_parent;
76 	list_del_init(&child->ptrace_entry);
77 
78 	if (task_is_traced(child))
79 		ptrace_untrace(child);
80 }
81 
82 /*
83  * Check that we have indeed attached to the thing..
84  */
85 int ptrace_check_attach(struct task_struct *child, int kill)
86 {
87 	int ret = -ESRCH;
88 
89 	/*
90 	 * We take the read lock around doing both checks to close a
91 	 * possible race where someone else was tracing our child and
92 	 * detached between these two checks.  After this locked check,
93 	 * we are sure that this is our traced child and that can only
94 	 * be changed by us so it's not changing right after this.
95 	 */
96 	read_lock(&tasklist_lock);
97 	if ((child->ptrace & PT_PTRACED) && child->parent == current) {
98 		ret = 0;
99 		/*
100 		 * child->sighand can't be NULL, release_task()
101 		 * does ptrace_unlink() before __exit_signal().
102 		 */
103 		spin_lock_irq(&child->sighand->siglock);
104 		if (task_is_stopped(child))
105 			child->state = TASK_TRACED;
106 		else if (!task_is_traced(child) && !kill)
107 			ret = -ESRCH;
108 		spin_unlock_irq(&child->sighand->siglock);
109 	}
110 	read_unlock(&tasklist_lock);
111 
112 	if (!ret && !kill)
113 		ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
114 
115 	/* All systems go.. */
116 	return ret;
117 }
118 
119 int __ptrace_may_access(struct task_struct *task, unsigned int mode)
120 {
121 	const struct cred *cred = current_cred(), *tcred;
122 
123 	/* May we inspect the given task?
124 	 * This check is used both for attaching with ptrace
125 	 * and for allowing access to sensitive information in /proc.
126 	 *
127 	 * ptrace_attach denies several cases that /proc allows
128 	 * because setting up the necessary parent/child relationship
129 	 * or halting the specified task is impossible.
130 	 */
131 	int dumpable = 0;
132 	/* Don't let security modules deny introspection */
133 	if (task == current)
134 		return 0;
135 	rcu_read_lock();
136 	tcred = __task_cred(task);
137 	if ((cred->uid != tcred->euid ||
138 	     cred->uid != tcred->suid ||
139 	     cred->uid != tcred->uid  ||
140 	     cred->gid != tcred->egid ||
141 	     cred->gid != tcred->sgid ||
142 	     cred->gid != tcred->gid) &&
143 	    !capable(CAP_SYS_PTRACE)) {
144 		rcu_read_unlock();
145 		return -EPERM;
146 	}
147 	rcu_read_unlock();
148 	smp_rmb();
149 	if (task->mm)
150 		dumpable = get_dumpable(task->mm);
151 	if (!dumpable && !capable(CAP_SYS_PTRACE))
152 		return -EPERM;
153 
154 	return security_ptrace_access_check(task, mode);
155 }
156 
157 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
158 {
159 	int err;
160 	task_lock(task);
161 	err = __ptrace_may_access(task, mode);
162 	task_unlock(task);
163 	return !err;
164 }
165 
166 int ptrace_attach(struct task_struct *task)
167 {
168 	int retval;
169 
170 	audit_ptrace(task);
171 
172 	retval = -EPERM;
173 	if (unlikely(task->flags & PF_KTHREAD))
174 		goto out;
175 	if (same_thread_group(task, current))
176 		goto out;
177 
178 	/*
179 	 * Protect exec's credential calculations against our interference;
180 	 * interference; SUID, SGID and LSM creds get determined differently
181 	 * under ptrace.
182 	 */
183 	retval = -ERESTARTNOINTR;
184 	if (mutex_lock_interruptible(&task->cred_guard_mutex))
185 		goto out;
186 
187 	task_lock(task);
188 	retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
189 	task_unlock(task);
190 	if (retval)
191 		goto unlock_creds;
192 
193 	write_lock_irq(&tasklist_lock);
194 	retval = -EPERM;
195 	if (unlikely(task->exit_state))
196 		goto unlock_tasklist;
197 	if (task->ptrace)
198 		goto unlock_tasklist;
199 
200 	task->ptrace = PT_PTRACED;
201 	if (capable(CAP_SYS_PTRACE))
202 		task->ptrace |= PT_PTRACE_CAP;
203 
204 	__ptrace_link(task, current);
205 	send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
206 
207 	retval = 0;
208 unlock_tasklist:
209 	write_unlock_irq(&tasklist_lock);
210 unlock_creds:
211 	mutex_unlock(&task->cred_guard_mutex);
212 out:
213 	return retval;
214 }
215 
216 /**
217  * ptrace_traceme  --  helper for PTRACE_TRACEME
218  *
219  * Performs checks and sets PT_PTRACED.
220  * Should be used by all ptrace implementations for PTRACE_TRACEME.
221  */
222 int ptrace_traceme(void)
223 {
224 	int ret = -EPERM;
225 
226 	write_lock_irq(&tasklist_lock);
227 	/* Are we already being traced? */
228 	if (!current->ptrace) {
229 		ret = security_ptrace_traceme(current->parent);
230 		/*
231 		 * Check PF_EXITING to ensure ->real_parent has not passed
232 		 * exit_ptrace(). Otherwise we don't report the error but
233 		 * pretend ->real_parent untraces us right after return.
234 		 */
235 		if (!ret && !(current->real_parent->flags & PF_EXITING)) {
236 			current->ptrace = PT_PTRACED;
237 			__ptrace_link(current, current->real_parent);
238 		}
239 	}
240 	write_unlock_irq(&tasklist_lock);
241 
242 	return ret;
243 }
244 
245 /*
246  * Called with irqs disabled, returns true if childs should reap themselves.
247  */
248 static int ignoring_children(struct sighand_struct *sigh)
249 {
250 	int ret;
251 	spin_lock(&sigh->siglock);
252 	ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
253 	      (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
254 	spin_unlock(&sigh->siglock);
255 	return ret;
256 }
257 
258 /*
259  * Called with tasklist_lock held for writing.
260  * Unlink a traced task, and clean it up if it was a traced zombie.
261  * Return true if it needs to be reaped with release_task().
262  * (We can't call release_task() here because we already hold tasklist_lock.)
263  *
264  * If it's a zombie, our attachedness prevented normal parent notification
265  * or self-reaping.  Do notification now if it would have happened earlier.
266  * If it should reap itself, return true.
267  *
268  * If it's our own child, there is no notification to do. But if our normal
269  * children self-reap, then this child was prevented by ptrace and we must
270  * reap it now, in that case we must also wake up sub-threads sleeping in
271  * do_wait().
272  */
273 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
274 {
275 	__ptrace_unlink(p);
276 
277 	if (p->exit_state == EXIT_ZOMBIE) {
278 		if (!task_detached(p) && thread_group_empty(p)) {
279 			if (!same_thread_group(p->real_parent, tracer))
280 				do_notify_parent(p, p->exit_signal);
281 			else if (ignoring_children(tracer->sighand)) {
282 				__wake_up_parent(p, tracer);
283 				p->exit_signal = -1;
284 			}
285 		}
286 		if (task_detached(p)) {
287 			/* Mark it as in the process of being reaped. */
288 			p->exit_state = EXIT_DEAD;
289 			return true;
290 		}
291 	}
292 
293 	return false;
294 }
295 
296 int ptrace_detach(struct task_struct *child, unsigned int data)
297 {
298 	bool dead = false;
299 
300 	if (!valid_signal(data))
301 		return -EIO;
302 
303 	/* Architecture-specific hardware disable .. */
304 	ptrace_disable(child);
305 	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
306 
307 	write_lock_irq(&tasklist_lock);
308 	/*
309 	 * This child can be already killed. Make sure de_thread() or
310 	 * our sub-thread doing do_wait() didn't do release_task() yet.
311 	 */
312 	if (child->ptrace) {
313 		child->exit_code = data;
314 		dead = __ptrace_detach(current, child);
315 		if (!child->exit_state)
316 			wake_up_process(child);
317 	}
318 	write_unlock_irq(&tasklist_lock);
319 
320 	if (unlikely(dead))
321 		release_task(child);
322 
323 	return 0;
324 }
325 
326 /*
327  * Detach all tasks we were using ptrace on.
328  */
329 void exit_ptrace(struct task_struct *tracer)
330 {
331 	struct task_struct *p, *n;
332 	LIST_HEAD(ptrace_dead);
333 
334 	write_lock_irq(&tasklist_lock);
335 	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
336 		if (__ptrace_detach(tracer, p))
337 			list_add(&p->ptrace_entry, &ptrace_dead);
338 	}
339 	write_unlock_irq(&tasklist_lock);
340 
341 	BUG_ON(!list_empty(&tracer->ptraced));
342 
343 	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
344 		list_del_init(&p->ptrace_entry);
345 		release_task(p);
346 	}
347 }
348 
349 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
350 {
351 	int copied = 0;
352 
353 	while (len > 0) {
354 		char buf[128];
355 		int this_len, retval;
356 
357 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
358 		retval = access_process_vm(tsk, src, buf, this_len, 0);
359 		if (!retval) {
360 			if (copied)
361 				break;
362 			return -EIO;
363 		}
364 		if (copy_to_user(dst, buf, retval))
365 			return -EFAULT;
366 		copied += retval;
367 		src += retval;
368 		dst += retval;
369 		len -= retval;
370 	}
371 	return copied;
372 }
373 
374 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
375 {
376 	int copied = 0;
377 
378 	while (len > 0) {
379 		char buf[128];
380 		int this_len, retval;
381 
382 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
383 		if (copy_from_user(buf, src, this_len))
384 			return -EFAULT;
385 		retval = access_process_vm(tsk, dst, buf, this_len, 1);
386 		if (!retval) {
387 			if (copied)
388 				break;
389 			return -EIO;
390 		}
391 		copied += retval;
392 		src += retval;
393 		dst += retval;
394 		len -= retval;
395 	}
396 	return copied;
397 }
398 
399 static int ptrace_setoptions(struct task_struct *child, long data)
400 {
401 	child->ptrace &= ~PT_TRACE_MASK;
402 
403 	if (data & PTRACE_O_TRACESYSGOOD)
404 		child->ptrace |= PT_TRACESYSGOOD;
405 
406 	if (data & PTRACE_O_TRACEFORK)
407 		child->ptrace |= PT_TRACE_FORK;
408 
409 	if (data & PTRACE_O_TRACEVFORK)
410 		child->ptrace |= PT_TRACE_VFORK;
411 
412 	if (data & PTRACE_O_TRACECLONE)
413 		child->ptrace |= PT_TRACE_CLONE;
414 
415 	if (data & PTRACE_O_TRACEEXEC)
416 		child->ptrace |= PT_TRACE_EXEC;
417 
418 	if (data & PTRACE_O_TRACEVFORKDONE)
419 		child->ptrace |= PT_TRACE_VFORK_DONE;
420 
421 	if (data & PTRACE_O_TRACEEXIT)
422 		child->ptrace |= PT_TRACE_EXIT;
423 
424 	return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
425 }
426 
427 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
428 {
429 	unsigned long flags;
430 	int error = -ESRCH;
431 
432 	if (lock_task_sighand(child, &flags)) {
433 		error = -EINVAL;
434 		if (likely(child->last_siginfo != NULL)) {
435 			*info = *child->last_siginfo;
436 			error = 0;
437 		}
438 		unlock_task_sighand(child, &flags);
439 	}
440 	return error;
441 }
442 
443 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
444 {
445 	unsigned long flags;
446 	int error = -ESRCH;
447 
448 	if (lock_task_sighand(child, &flags)) {
449 		error = -EINVAL;
450 		if (likely(child->last_siginfo != NULL)) {
451 			*child->last_siginfo = *info;
452 			error = 0;
453 		}
454 		unlock_task_sighand(child, &flags);
455 	}
456 	return error;
457 }
458 
459 
460 #ifdef PTRACE_SINGLESTEP
461 #define is_singlestep(request)		((request) == PTRACE_SINGLESTEP)
462 #else
463 #define is_singlestep(request)		0
464 #endif
465 
466 #ifdef PTRACE_SINGLEBLOCK
467 #define is_singleblock(request)		((request) == PTRACE_SINGLEBLOCK)
468 #else
469 #define is_singleblock(request)		0
470 #endif
471 
472 #ifdef PTRACE_SYSEMU
473 #define is_sysemu_singlestep(request)	((request) == PTRACE_SYSEMU_SINGLESTEP)
474 #else
475 #define is_sysemu_singlestep(request)	0
476 #endif
477 
478 static int ptrace_resume(struct task_struct *child, long request, long data)
479 {
480 	if (!valid_signal(data))
481 		return -EIO;
482 
483 	if (request == PTRACE_SYSCALL)
484 		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
485 	else
486 		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
487 
488 #ifdef TIF_SYSCALL_EMU
489 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
490 		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
491 	else
492 		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
493 #endif
494 
495 	if (is_singleblock(request)) {
496 		if (unlikely(!arch_has_block_step()))
497 			return -EIO;
498 		user_enable_block_step(child);
499 	} else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
500 		if (unlikely(!arch_has_single_step()))
501 			return -EIO;
502 		user_enable_single_step(child);
503 	} else {
504 		user_disable_single_step(child);
505 	}
506 
507 	child->exit_code = data;
508 	wake_up_process(child);
509 
510 	return 0;
511 }
512 
513 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
514 
515 static const struct user_regset *
516 find_regset(const struct user_regset_view *view, unsigned int type)
517 {
518 	const struct user_regset *regset;
519 	int n;
520 
521 	for (n = 0; n < view->n; ++n) {
522 		regset = view->regsets + n;
523 		if (regset->core_note_type == type)
524 			return regset;
525 	}
526 
527 	return NULL;
528 }
529 
530 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
531 			 struct iovec *kiov)
532 {
533 	const struct user_regset_view *view = task_user_regset_view(task);
534 	const struct user_regset *regset = find_regset(view, type);
535 	int regset_no;
536 
537 	if (!regset || (kiov->iov_len % regset->size) != 0)
538 		return -EINVAL;
539 
540 	regset_no = regset - view->regsets;
541 	kiov->iov_len = min(kiov->iov_len,
542 			    (__kernel_size_t) (regset->n * regset->size));
543 
544 	if (req == PTRACE_GETREGSET)
545 		return copy_regset_to_user(task, view, regset_no, 0,
546 					   kiov->iov_len, kiov->iov_base);
547 	else
548 		return copy_regset_from_user(task, view, regset_no, 0,
549 					     kiov->iov_len, kiov->iov_base);
550 }
551 
552 #endif
553 
554 int ptrace_request(struct task_struct *child, long request,
555 		   long addr, long data)
556 {
557 	int ret = -EIO;
558 	siginfo_t siginfo;
559 
560 	switch (request) {
561 	case PTRACE_PEEKTEXT:
562 	case PTRACE_PEEKDATA:
563 		return generic_ptrace_peekdata(child, addr, data);
564 	case PTRACE_POKETEXT:
565 	case PTRACE_POKEDATA:
566 		return generic_ptrace_pokedata(child, addr, data);
567 
568 #ifdef PTRACE_OLDSETOPTIONS
569 	case PTRACE_OLDSETOPTIONS:
570 #endif
571 	case PTRACE_SETOPTIONS:
572 		ret = ptrace_setoptions(child, data);
573 		break;
574 	case PTRACE_GETEVENTMSG:
575 		ret = put_user(child->ptrace_message, (unsigned long __user *) data);
576 		break;
577 
578 	case PTRACE_GETSIGINFO:
579 		ret = ptrace_getsiginfo(child, &siginfo);
580 		if (!ret)
581 			ret = copy_siginfo_to_user((siginfo_t __user *) data,
582 						   &siginfo);
583 		break;
584 
585 	case PTRACE_SETSIGINFO:
586 		if (copy_from_user(&siginfo, (siginfo_t __user *) data,
587 				   sizeof siginfo))
588 			ret = -EFAULT;
589 		else
590 			ret = ptrace_setsiginfo(child, &siginfo);
591 		break;
592 
593 	case PTRACE_DETACH:	 /* detach a process that was attached. */
594 		ret = ptrace_detach(child, data);
595 		break;
596 
597 #ifdef CONFIG_BINFMT_ELF_FDPIC
598 	case PTRACE_GETFDPIC: {
599 		struct mm_struct *mm = get_task_mm(child);
600 		unsigned long tmp = 0;
601 
602 		ret = -ESRCH;
603 		if (!mm)
604 			break;
605 
606 		switch (addr) {
607 		case PTRACE_GETFDPIC_EXEC:
608 			tmp = mm->context.exec_fdpic_loadmap;
609 			break;
610 		case PTRACE_GETFDPIC_INTERP:
611 			tmp = mm->context.interp_fdpic_loadmap;
612 			break;
613 		default:
614 			break;
615 		}
616 		mmput(mm);
617 
618 		ret = put_user(tmp, (unsigned long __user *) data);
619 		break;
620 	}
621 #endif
622 
623 #ifdef PTRACE_SINGLESTEP
624 	case PTRACE_SINGLESTEP:
625 #endif
626 #ifdef PTRACE_SINGLEBLOCK
627 	case PTRACE_SINGLEBLOCK:
628 #endif
629 #ifdef PTRACE_SYSEMU
630 	case PTRACE_SYSEMU:
631 	case PTRACE_SYSEMU_SINGLESTEP:
632 #endif
633 	case PTRACE_SYSCALL:
634 	case PTRACE_CONT:
635 		return ptrace_resume(child, request, data);
636 
637 	case PTRACE_KILL:
638 		if (child->exit_state)	/* already dead */
639 			return 0;
640 		return ptrace_resume(child, request, SIGKILL);
641 
642 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
643 	case PTRACE_GETREGSET:
644 	case PTRACE_SETREGSET:
645 	{
646 		struct iovec kiov;
647 		struct iovec __user *uiov = (struct iovec __user *) data;
648 
649 		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
650 			return -EFAULT;
651 
652 		if (__get_user(kiov.iov_base, &uiov->iov_base) ||
653 		    __get_user(kiov.iov_len, &uiov->iov_len))
654 			return -EFAULT;
655 
656 		ret = ptrace_regset(child, request, addr, &kiov);
657 		if (!ret)
658 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
659 		break;
660 	}
661 #endif
662 	default:
663 		break;
664 	}
665 
666 	return ret;
667 }
668 
669 static struct task_struct *ptrace_get_task_struct(pid_t pid)
670 {
671 	struct task_struct *child;
672 
673 	rcu_read_lock();
674 	child = find_task_by_vpid(pid);
675 	if (child)
676 		get_task_struct(child);
677 	rcu_read_unlock();
678 
679 	if (!child)
680 		return ERR_PTR(-ESRCH);
681 	return child;
682 }
683 
684 #ifndef arch_ptrace_attach
685 #define arch_ptrace_attach(child)	do { } while (0)
686 #endif
687 
688 SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
689 {
690 	struct task_struct *child;
691 	long ret;
692 
693 	if (request == PTRACE_TRACEME) {
694 		ret = ptrace_traceme();
695 		if (!ret)
696 			arch_ptrace_attach(current);
697 		goto out;
698 	}
699 
700 	child = ptrace_get_task_struct(pid);
701 	if (IS_ERR(child)) {
702 		ret = PTR_ERR(child);
703 		goto out;
704 	}
705 
706 	if (request == PTRACE_ATTACH) {
707 		ret = ptrace_attach(child);
708 		/*
709 		 * Some architectures need to do book-keeping after
710 		 * a ptrace attach.
711 		 */
712 		if (!ret)
713 			arch_ptrace_attach(child);
714 		goto out_put_task_struct;
715 	}
716 
717 	ret = ptrace_check_attach(child, request == PTRACE_KILL);
718 	if (ret < 0)
719 		goto out_put_task_struct;
720 
721 	ret = arch_ptrace(child, request, addr, data);
722 
723  out_put_task_struct:
724 	put_task_struct(child);
725  out:
726 	return ret;
727 }
728 
729 int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
730 {
731 	unsigned long tmp;
732 	int copied;
733 
734 	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
735 	if (copied != sizeof(tmp))
736 		return -EIO;
737 	return put_user(tmp, (unsigned long __user *)data);
738 }
739 
740 int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
741 {
742 	int copied;
743 
744 	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
745 	return (copied == sizeof(data)) ? 0 : -EIO;
746 }
747 
748 #if defined CONFIG_COMPAT
749 #include <linux/compat.h>
750 
751 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
752 			  compat_ulong_t addr, compat_ulong_t data)
753 {
754 	compat_ulong_t __user *datap = compat_ptr(data);
755 	compat_ulong_t word;
756 	siginfo_t siginfo;
757 	int ret;
758 
759 	switch (request) {
760 	case PTRACE_PEEKTEXT:
761 	case PTRACE_PEEKDATA:
762 		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
763 		if (ret != sizeof(word))
764 			ret = -EIO;
765 		else
766 			ret = put_user(word, datap);
767 		break;
768 
769 	case PTRACE_POKETEXT:
770 	case PTRACE_POKEDATA:
771 		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
772 		ret = (ret != sizeof(data) ? -EIO : 0);
773 		break;
774 
775 	case PTRACE_GETEVENTMSG:
776 		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
777 		break;
778 
779 	case PTRACE_GETSIGINFO:
780 		ret = ptrace_getsiginfo(child, &siginfo);
781 		if (!ret)
782 			ret = copy_siginfo_to_user32(
783 				(struct compat_siginfo __user *) datap,
784 				&siginfo);
785 		break;
786 
787 	case PTRACE_SETSIGINFO:
788 		memset(&siginfo, 0, sizeof siginfo);
789 		if (copy_siginfo_from_user32(
790 			    &siginfo, (struct compat_siginfo __user *) datap))
791 			ret = -EFAULT;
792 		else
793 			ret = ptrace_setsiginfo(child, &siginfo);
794 		break;
795 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
796 	case PTRACE_GETREGSET:
797 	case PTRACE_SETREGSET:
798 	{
799 		struct iovec kiov;
800 		struct compat_iovec __user *uiov =
801 			(struct compat_iovec __user *) datap;
802 		compat_uptr_t ptr;
803 		compat_size_t len;
804 
805 		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
806 			return -EFAULT;
807 
808 		if (__get_user(ptr, &uiov->iov_base) ||
809 		    __get_user(len, &uiov->iov_len))
810 			return -EFAULT;
811 
812 		kiov.iov_base = compat_ptr(ptr);
813 		kiov.iov_len = len;
814 
815 		ret = ptrace_regset(child, request, addr, &kiov);
816 		if (!ret)
817 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
818 		break;
819 	}
820 #endif
821 
822 	default:
823 		ret = ptrace_request(child, request, addr, data);
824 	}
825 
826 	return ret;
827 }
828 
829 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
830 				  compat_long_t addr, compat_long_t data)
831 {
832 	struct task_struct *child;
833 	long ret;
834 
835 	if (request == PTRACE_TRACEME) {
836 		ret = ptrace_traceme();
837 		goto out;
838 	}
839 
840 	child = ptrace_get_task_struct(pid);
841 	if (IS_ERR(child)) {
842 		ret = PTR_ERR(child);
843 		goto out;
844 	}
845 
846 	if (request == PTRACE_ATTACH) {
847 		ret = ptrace_attach(child);
848 		/*
849 		 * Some architectures need to do book-keeping after
850 		 * a ptrace attach.
851 		 */
852 		if (!ret)
853 			arch_ptrace_attach(child);
854 		goto out_put_task_struct;
855 	}
856 
857 	ret = ptrace_check_attach(child, request == PTRACE_KILL);
858 	if (!ret)
859 		ret = compat_arch_ptrace(child, request, addr, data);
860 
861  out_put_task_struct:
862 	put_task_struct(child);
863  out:
864 	return ret;
865 }
866 #endif	/* CONFIG_COMPAT */
867