xref: /linux/kernel/ptrace.c (revision 26b0d14106954ae46d2f4f7eec3481828a210f7d)
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/export.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 #include <linux/hw_breakpoint.h>
26 #include <linux/cn_proc.h>
27 
28 
29 static int ptrace_trapping_sleep_fn(void *flags)
30 {
31 	schedule();
32 	return 0;
33 }
34 
35 /*
36  * ptrace a task: make the debugger its new parent and
37  * move it to the ptrace list.
38  *
39  * Must be called with the tasklist lock write-held.
40  */
41 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
42 {
43 	BUG_ON(!list_empty(&child->ptrace_entry));
44 	list_add(&child->ptrace_entry, &new_parent->ptraced);
45 	child->parent = new_parent;
46 }
47 
48 /**
49  * __ptrace_unlink - unlink ptracee and restore its execution state
50  * @child: ptracee to be unlinked
51  *
52  * Remove @child from the ptrace list, move it back to the original parent,
53  * and restore the execution state so that it conforms to the group stop
54  * state.
55  *
56  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
57  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
58  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
59  * If the ptracer is exiting, the ptracee can be in any state.
60  *
61  * After detach, the ptracee should be in a state which conforms to the
62  * group stop.  If the group is stopped or in the process of stopping, the
63  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
64  * up from TASK_TRACED.
65  *
66  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
67  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
68  * to but in the opposite direction of what happens while attaching to a
69  * stopped task.  However, in this direction, the intermediate RUNNING
70  * state is not hidden even from the current ptracer and if it immediately
71  * re-attaches and performs a WNOHANG wait(2), it may fail.
72  *
73  * CONTEXT:
74  * write_lock_irq(tasklist_lock)
75  */
76 void __ptrace_unlink(struct task_struct *child)
77 {
78 	BUG_ON(!child->ptrace);
79 
80 	child->ptrace = 0;
81 	child->parent = child->real_parent;
82 	list_del_init(&child->ptrace_entry);
83 
84 	spin_lock(&child->sighand->siglock);
85 
86 	/*
87 	 * Clear all pending traps and TRAPPING.  TRAPPING should be
88 	 * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
89 	 */
90 	task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
91 	task_clear_jobctl_trapping(child);
92 
93 	/*
94 	 * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
95 	 * @child isn't dead.
96 	 */
97 	if (!(child->flags & PF_EXITING) &&
98 	    (child->signal->flags & SIGNAL_STOP_STOPPED ||
99 	     child->signal->group_stop_count)) {
100 		child->jobctl |= JOBCTL_STOP_PENDING;
101 
102 		/*
103 		 * This is only possible if this thread was cloned by the
104 		 * traced task running in the stopped group, set the signal
105 		 * for the future reports.
106 		 * FIXME: we should change ptrace_init_task() to handle this
107 		 * case.
108 		 */
109 		if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
110 			child->jobctl |= SIGSTOP;
111 	}
112 
113 	/*
114 	 * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
115 	 * @child in the butt.  Note that @resume should be used iff @child
116 	 * is in TASK_TRACED; otherwise, we might unduly disrupt
117 	 * TASK_KILLABLE sleeps.
118 	 */
119 	if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
120 		signal_wake_up(child, task_is_traced(child));
121 
122 	spin_unlock(&child->sighand->siglock);
123 }
124 
125 /**
126  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
127  * @child: ptracee to check for
128  * @ignore_state: don't check whether @child is currently %TASK_TRACED
129  *
130  * Check whether @child is being ptraced by %current and ready for further
131  * ptrace operations.  If @ignore_state is %false, @child also should be in
132  * %TASK_TRACED state and on return the child is guaranteed to be traced
133  * and not executing.  If @ignore_state is %true, @child can be in any
134  * state.
135  *
136  * CONTEXT:
137  * Grabs and releases tasklist_lock and @child->sighand->siglock.
138  *
139  * RETURNS:
140  * 0 on success, -ESRCH if %child is not ready.
141  */
142 int ptrace_check_attach(struct task_struct *child, bool ignore_state)
143 {
144 	int ret = -ESRCH;
145 
146 	/*
147 	 * We take the read lock around doing both checks to close a
148 	 * possible race where someone else was tracing our child and
149 	 * detached between these two checks.  After this locked check,
150 	 * we are sure that this is our traced child and that can only
151 	 * be changed by us so it's not changing right after this.
152 	 */
153 	read_lock(&tasklist_lock);
154 	if ((child->ptrace & PT_PTRACED) && child->parent == current) {
155 		/*
156 		 * child->sighand can't be NULL, release_task()
157 		 * does ptrace_unlink() before __exit_signal().
158 		 */
159 		spin_lock_irq(&child->sighand->siglock);
160 		WARN_ON_ONCE(task_is_stopped(child));
161 		if (ignore_state || (task_is_traced(child) &&
162 				     !(child->jobctl & JOBCTL_LISTENING)))
163 			ret = 0;
164 		spin_unlock_irq(&child->sighand->siglock);
165 	}
166 	read_unlock(&tasklist_lock);
167 
168 	if (!ret && !ignore_state)
169 		ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
170 
171 	/* All systems go.. */
172 	return ret;
173 }
174 
175 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
176 {
177 	if (mode & PTRACE_MODE_NOAUDIT)
178 		return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
179 	else
180 		return has_ns_capability(current, ns, CAP_SYS_PTRACE);
181 }
182 
183 int __ptrace_may_access(struct task_struct *task, unsigned int mode)
184 {
185 	const struct cred *cred = current_cred(), *tcred;
186 
187 	/* May we inspect the given task?
188 	 * This check is used both for attaching with ptrace
189 	 * and for allowing access to sensitive information in /proc.
190 	 *
191 	 * ptrace_attach denies several cases that /proc allows
192 	 * because setting up the necessary parent/child relationship
193 	 * or halting the specified task is impossible.
194 	 */
195 	int dumpable = 0;
196 	/* Don't let security modules deny introspection */
197 	if (task == current)
198 		return 0;
199 	rcu_read_lock();
200 	tcred = __task_cred(task);
201 	if (uid_eq(cred->uid, tcred->euid) &&
202 	    uid_eq(cred->uid, tcred->suid) &&
203 	    uid_eq(cred->uid, tcred->uid)  &&
204 	    gid_eq(cred->gid, tcred->egid) &&
205 	    gid_eq(cred->gid, tcred->sgid) &&
206 	    gid_eq(cred->gid, tcred->gid))
207 		goto ok;
208 	if (ptrace_has_cap(tcred->user_ns, mode))
209 		goto ok;
210 	rcu_read_unlock();
211 	return -EPERM;
212 ok:
213 	rcu_read_unlock();
214 	smp_rmb();
215 	if (task->mm)
216 		dumpable = get_dumpable(task->mm);
217 	if (!dumpable  && !ptrace_has_cap(task_user_ns(task), mode))
218 		return -EPERM;
219 
220 	return security_ptrace_access_check(task, mode);
221 }
222 
223 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
224 {
225 	int err;
226 	task_lock(task);
227 	err = __ptrace_may_access(task, mode);
228 	task_unlock(task);
229 	return !err;
230 }
231 
232 static int ptrace_attach(struct task_struct *task, long request,
233 			 unsigned long addr,
234 			 unsigned long flags)
235 {
236 	bool seize = (request == PTRACE_SEIZE);
237 	int retval;
238 
239 	retval = -EIO;
240 	if (seize) {
241 		if (addr != 0)
242 			goto out;
243 		if (flags & ~(unsigned long)PTRACE_O_MASK)
244 			goto out;
245 		flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
246 	} else {
247 		flags = PT_PTRACED;
248 	}
249 
250 	audit_ptrace(task);
251 
252 	retval = -EPERM;
253 	if (unlikely(task->flags & PF_KTHREAD))
254 		goto out;
255 	if (same_thread_group(task, current))
256 		goto out;
257 
258 	/*
259 	 * Protect exec's credential calculations against our interference;
260 	 * SUID, SGID and LSM creds get determined differently
261 	 * under ptrace.
262 	 */
263 	retval = -ERESTARTNOINTR;
264 	if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
265 		goto out;
266 
267 	task_lock(task);
268 	retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
269 	task_unlock(task);
270 	if (retval)
271 		goto unlock_creds;
272 
273 	write_lock_irq(&tasklist_lock);
274 	retval = -EPERM;
275 	if (unlikely(task->exit_state))
276 		goto unlock_tasklist;
277 	if (task->ptrace)
278 		goto unlock_tasklist;
279 
280 	if (seize)
281 		flags |= PT_SEIZED;
282 	if (ns_capable(task_user_ns(task), CAP_SYS_PTRACE))
283 		flags |= PT_PTRACE_CAP;
284 	task->ptrace = flags;
285 
286 	__ptrace_link(task, current);
287 
288 	/* SEIZE doesn't trap tracee on attach */
289 	if (!seize)
290 		send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
291 
292 	spin_lock(&task->sighand->siglock);
293 
294 	/*
295 	 * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
296 	 * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
297 	 * will be cleared if the child completes the transition or any
298 	 * event which clears the group stop states happens.  We'll wait
299 	 * for the transition to complete before returning from this
300 	 * function.
301 	 *
302 	 * This hides STOPPED -> RUNNING -> TRACED transition from the
303 	 * attaching thread but a different thread in the same group can
304 	 * still observe the transient RUNNING state.  IOW, if another
305 	 * thread's WNOHANG wait(2) on the stopped tracee races against
306 	 * ATTACH, the wait(2) may fail due to the transient RUNNING.
307 	 *
308 	 * The following task_is_stopped() test is safe as both transitions
309 	 * in and out of STOPPED are protected by siglock.
310 	 */
311 	if (task_is_stopped(task) &&
312 	    task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
313 		signal_wake_up(task, 1);
314 
315 	spin_unlock(&task->sighand->siglock);
316 
317 	retval = 0;
318 unlock_tasklist:
319 	write_unlock_irq(&tasklist_lock);
320 unlock_creds:
321 	mutex_unlock(&task->signal->cred_guard_mutex);
322 out:
323 	if (!retval) {
324 		wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
325 			    ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
326 		proc_ptrace_connector(task, PTRACE_ATTACH);
327 	}
328 
329 	return retval;
330 }
331 
332 /**
333  * ptrace_traceme  --  helper for PTRACE_TRACEME
334  *
335  * Performs checks and sets PT_PTRACED.
336  * Should be used by all ptrace implementations for PTRACE_TRACEME.
337  */
338 static int ptrace_traceme(void)
339 {
340 	int ret = -EPERM;
341 
342 	write_lock_irq(&tasklist_lock);
343 	/* Are we already being traced? */
344 	if (!current->ptrace) {
345 		ret = security_ptrace_traceme(current->parent);
346 		/*
347 		 * Check PF_EXITING to ensure ->real_parent has not passed
348 		 * exit_ptrace(). Otherwise we don't report the error but
349 		 * pretend ->real_parent untraces us right after return.
350 		 */
351 		if (!ret && !(current->real_parent->flags & PF_EXITING)) {
352 			current->ptrace = PT_PTRACED;
353 			__ptrace_link(current, current->real_parent);
354 		}
355 	}
356 	write_unlock_irq(&tasklist_lock);
357 
358 	return ret;
359 }
360 
361 /*
362  * Called with irqs disabled, returns true if childs should reap themselves.
363  */
364 static int ignoring_children(struct sighand_struct *sigh)
365 {
366 	int ret;
367 	spin_lock(&sigh->siglock);
368 	ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
369 	      (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
370 	spin_unlock(&sigh->siglock);
371 	return ret;
372 }
373 
374 /*
375  * Called with tasklist_lock held for writing.
376  * Unlink a traced task, and clean it up if it was a traced zombie.
377  * Return true if it needs to be reaped with release_task().
378  * (We can't call release_task() here because we already hold tasklist_lock.)
379  *
380  * If it's a zombie, our attachedness prevented normal parent notification
381  * or self-reaping.  Do notification now if it would have happened earlier.
382  * If it should reap itself, return true.
383  *
384  * If it's our own child, there is no notification to do. But if our normal
385  * children self-reap, then this child was prevented by ptrace and we must
386  * reap it now, in that case we must also wake up sub-threads sleeping in
387  * do_wait().
388  */
389 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
390 {
391 	bool dead;
392 
393 	__ptrace_unlink(p);
394 
395 	if (p->exit_state != EXIT_ZOMBIE)
396 		return false;
397 
398 	dead = !thread_group_leader(p);
399 
400 	if (!dead && thread_group_empty(p)) {
401 		if (!same_thread_group(p->real_parent, tracer))
402 			dead = do_notify_parent(p, p->exit_signal);
403 		else if (ignoring_children(tracer->sighand)) {
404 			__wake_up_parent(p, tracer);
405 			dead = true;
406 		}
407 	}
408 	/* Mark it as in the process of being reaped. */
409 	if (dead)
410 		p->exit_state = EXIT_DEAD;
411 	return dead;
412 }
413 
414 static int ptrace_detach(struct task_struct *child, unsigned int data)
415 {
416 	bool dead = false;
417 
418 	if (!valid_signal(data))
419 		return -EIO;
420 
421 	/* Architecture-specific hardware disable .. */
422 	ptrace_disable(child);
423 	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
424 
425 	write_lock_irq(&tasklist_lock);
426 	/*
427 	 * This child can be already killed. Make sure de_thread() or
428 	 * our sub-thread doing do_wait() didn't do release_task() yet.
429 	 */
430 	if (child->ptrace) {
431 		child->exit_code = data;
432 		dead = __ptrace_detach(current, child);
433 	}
434 	write_unlock_irq(&tasklist_lock);
435 
436 	proc_ptrace_connector(child, PTRACE_DETACH);
437 	if (unlikely(dead))
438 		release_task(child);
439 
440 	return 0;
441 }
442 
443 /*
444  * Detach all tasks we were using ptrace on. Called with tasklist held
445  * for writing, and returns with it held too. But note it can release
446  * and reacquire the lock.
447  */
448 void exit_ptrace(struct task_struct *tracer)
449 	__releases(&tasklist_lock)
450 	__acquires(&tasklist_lock)
451 {
452 	struct task_struct *p, *n;
453 	LIST_HEAD(ptrace_dead);
454 
455 	if (likely(list_empty(&tracer->ptraced)))
456 		return;
457 
458 	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
459 		if (__ptrace_detach(tracer, p))
460 			list_add(&p->ptrace_entry, &ptrace_dead);
461 	}
462 
463 	write_unlock_irq(&tasklist_lock);
464 	BUG_ON(!list_empty(&tracer->ptraced));
465 
466 	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
467 		list_del_init(&p->ptrace_entry);
468 		release_task(p);
469 	}
470 
471 	write_lock_irq(&tasklist_lock);
472 }
473 
474 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
475 {
476 	int copied = 0;
477 
478 	while (len > 0) {
479 		char buf[128];
480 		int this_len, retval;
481 
482 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
483 		retval = access_process_vm(tsk, src, buf, this_len, 0);
484 		if (!retval) {
485 			if (copied)
486 				break;
487 			return -EIO;
488 		}
489 		if (copy_to_user(dst, buf, retval))
490 			return -EFAULT;
491 		copied += retval;
492 		src += retval;
493 		dst += retval;
494 		len -= retval;
495 	}
496 	return copied;
497 }
498 
499 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
500 {
501 	int copied = 0;
502 
503 	while (len > 0) {
504 		char buf[128];
505 		int this_len, retval;
506 
507 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
508 		if (copy_from_user(buf, src, this_len))
509 			return -EFAULT;
510 		retval = access_process_vm(tsk, dst, buf, this_len, 1);
511 		if (!retval) {
512 			if (copied)
513 				break;
514 			return -EIO;
515 		}
516 		copied += retval;
517 		src += retval;
518 		dst += retval;
519 		len -= retval;
520 	}
521 	return copied;
522 }
523 
524 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
525 {
526 	unsigned flags;
527 
528 	if (data & ~(unsigned long)PTRACE_O_MASK)
529 		return -EINVAL;
530 
531 	/* Avoid intermediate state when all opts are cleared */
532 	flags = child->ptrace;
533 	flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
534 	flags |= (data << PT_OPT_FLAG_SHIFT);
535 	child->ptrace = flags;
536 
537 	return 0;
538 }
539 
540 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
541 {
542 	unsigned long flags;
543 	int error = -ESRCH;
544 
545 	if (lock_task_sighand(child, &flags)) {
546 		error = -EINVAL;
547 		if (likely(child->last_siginfo != NULL)) {
548 			*info = *child->last_siginfo;
549 			error = 0;
550 		}
551 		unlock_task_sighand(child, &flags);
552 	}
553 	return error;
554 }
555 
556 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
557 {
558 	unsigned long flags;
559 	int error = -ESRCH;
560 
561 	if (lock_task_sighand(child, &flags)) {
562 		error = -EINVAL;
563 		if (likely(child->last_siginfo != NULL)) {
564 			*child->last_siginfo = *info;
565 			error = 0;
566 		}
567 		unlock_task_sighand(child, &flags);
568 	}
569 	return error;
570 }
571 
572 
573 #ifdef PTRACE_SINGLESTEP
574 #define is_singlestep(request)		((request) == PTRACE_SINGLESTEP)
575 #else
576 #define is_singlestep(request)		0
577 #endif
578 
579 #ifdef PTRACE_SINGLEBLOCK
580 #define is_singleblock(request)		((request) == PTRACE_SINGLEBLOCK)
581 #else
582 #define is_singleblock(request)		0
583 #endif
584 
585 #ifdef PTRACE_SYSEMU
586 #define is_sysemu_singlestep(request)	((request) == PTRACE_SYSEMU_SINGLESTEP)
587 #else
588 #define is_sysemu_singlestep(request)	0
589 #endif
590 
591 static int ptrace_resume(struct task_struct *child, long request,
592 			 unsigned long data)
593 {
594 	if (!valid_signal(data))
595 		return -EIO;
596 
597 	if (request == PTRACE_SYSCALL)
598 		set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
599 	else
600 		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
601 
602 #ifdef TIF_SYSCALL_EMU
603 	if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
604 		set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
605 	else
606 		clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
607 #endif
608 
609 	if (is_singleblock(request)) {
610 		if (unlikely(!arch_has_block_step()))
611 			return -EIO;
612 		user_enable_block_step(child);
613 	} else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
614 		if (unlikely(!arch_has_single_step()))
615 			return -EIO;
616 		user_enable_single_step(child);
617 	} else {
618 		user_disable_single_step(child);
619 	}
620 
621 	child->exit_code = data;
622 	wake_up_state(child, __TASK_TRACED);
623 
624 	return 0;
625 }
626 
627 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
628 
629 static const struct user_regset *
630 find_regset(const struct user_regset_view *view, unsigned int type)
631 {
632 	const struct user_regset *regset;
633 	int n;
634 
635 	for (n = 0; n < view->n; ++n) {
636 		regset = view->regsets + n;
637 		if (regset->core_note_type == type)
638 			return regset;
639 	}
640 
641 	return NULL;
642 }
643 
644 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
645 			 struct iovec *kiov)
646 {
647 	const struct user_regset_view *view = task_user_regset_view(task);
648 	const struct user_regset *regset = find_regset(view, type);
649 	int regset_no;
650 
651 	if (!regset || (kiov->iov_len % regset->size) != 0)
652 		return -EINVAL;
653 
654 	regset_no = regset - view->regsets;
655 	kiov->iov_len = min(kiov->iov_len,
656 			    (__kernel_size_t) (regset->n * regset->size));
657 
658 	if (req == PTRACE_GETREGSET)
659 		return copy_regset_to_user(task, view, regset_no, 0,
660 					   kiov->iov_len, kiov->iov_base);
661 	else
662 		return copy_regset_from_user(task, view, regset_no, 0,
663 					     kiov->iov_len, kiov->iov_base);
664 }
665 
666 #endif
667 
668 int ptrace_request(struct task_struct *child, long request,
669 		   unsigned long addr, unsigned long data)
670 {
671 	bool seized = child->ptrace & PT_SEIZED;
672 	int ret = -EIO;
673 	siginfo_t siginfo, *si;
674 	void __user *datavp = (void __user *) data;
675 	unsigned long __user *datalp = datavp;
676 	unsigned long flags;
677 
678 	switch (request) {
679 	case PTRACE_PEEKTEXT:
680 	case PTRACE_PEEKDATA:
681 		return generic_ptrace_peekdata(child, addr, data);
682 	case PTRACE_POKETEXT:
683 	case PTRACE_POKEDATA:
684 		return generic_ptrace_pokedata(child, addr, data);
685 
686 #ifdef PTRACE_OLDSETOPTIONS
687 	case PTRACE_OLDSETOPTIONS:
688 #endif
689 	case PTRACE_SETOPTIONS:
690 		ret = ptrace_setoptions(child, data);
691 		break;
692 	case PTRACE_GETEVENTMSG:
693 		ret = put_user(child->ptrace_message, datalp);
694 		break;
695 
696 	case PTRACE_GETSIGINFO:
697 		ret = ptrace_getsiginfo(child, &siginfo);
698 		if (!ret)
699 			ret = copy_siginfo_to_user(datavp, &siginfo);
700 		break;
701 
702 	case PTRACE_SETSIGINFO:
703 		if (copy_from_user(&siginfo, datavp, sizeof siginfo))
704 			ret = -EFAULT;
705 		else
706 			ret = ptrace_setsiginfo(child, &siginfo);
707 		break;
708 
709 	case PTRACE_INTERRUPT:
710 		/*
711 		 * Stop tracee without any side-effect on signal or job
712 		 * control.  At least one trap is guaranteed to happen
713 		 * after this request.  If @child is already trapped, the
714 		 * current trap is not disturbed and another trap will
715 		 * happen after the current trap is ended with PTRACE_CONT.
716 		 *
717 		 * The actual trap might not be PTRACE_EVENT_STOP trap but
718 		 * the pending condition is cleared regardless.
719 		 */
720 		if (unlikely(!seized || !lock_task_sighand(child, &flags)))
721 			break;
722 
723 		/*
724 		 * INTERRUPT doesn't disturb existing trap sans one
725 		 * exception.  If ptracer issued LISTEN for the current
726 		 * STOP, this INTERRUPT should clear LISTEN and re-trap
727 		 * tracee into STOP.
728 		 */
729 		if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
730 			signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
731 
732 		unlock_task_sighand(child, &flags);
733 		ret = 0;
734 		break;
735 
736 	case PTRACE_LISTEN:
737 		/*
738 		 * Listen for events.  Tracee must be in STOP.  It's not
739 		 * resumed per-se but is not considered to be in TRACED by
740 		 * wait(2) or ptrace(2).  If an async event (e.g. group
741 		 * stop state change) happens, tracee will enter STOP trap
742 		 * again.  Alternatively, ptracer can issue INTERRUPT to
743 		 * finish listening and re-trap tracee into STOP.
744 		 */
745 		if (unlikely(!seized || !lock_task_sighand(child, &flags)))
746 			break;
747 
748 		si = child->last_siginfo;
749 		if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
750 			child->jobctl |= JOBCTL_LISTENING;
751 			/*
752 			 * If NOTIFY is set, it means event happened between
753 			 * start of this trap and now.  Trigger re-trap.
754 			 */
755 			if (child->jobctl & JOBCTL_TRAP_NOTIFY)
756 				signal_wake_up(child, true);
757 			ret = 0;
758 		}
759 		unlock_task_sighand(child, &flags);
760 		break;
761 
762 	case PTRACE_DETACH:	 /* detach a process that was attached. */
763 		ret = ptrace_detach(child, data);
764 		break;
765 
766 #ifdef CONFIG_BINFMT_ELF_FDPIC
767 	case PTRACE_GETFDPIC: {
768 		struct mm_struct *mm = get_task_mm(child);
769 		unsigned long tmp = 0;
770 
771 		ret = -ESRCH;
772 		if (!mm)
773 			break;
774 
775 		switch (addr) {
776 		case PTRACE_GETFDPIC_EXEC:
777 			tmp = mm->context.exec_fdpic_loadmap;
778 			break;
779 		case PTRACE_GETFDPIC_INTERP:
780 			tmp = mm->context.interp_fdpic_loadmap;
781 			break;
782 		default:
783 			break;
784 		}
785 		mmput(mm);
786 
787 		ret = put_user(tmp, datalp);
788 		break;
789 	}
790 #endif
791 
792 #ifdef PTRACE_SINGLESTEP
793 	case PTRACE_SINGLESTEP:
794 #endif
795 #ifdef PTRACE_SINGLEBLOCK
796 	case PTRACE_SINGLEBLOCK:
797 #endif
798 #ifdef PTRACE_SYSEMU
799 	case PTRACE_SYSEMU:
800 	case PTRACE_SYSEMU_SINGLESTEP:
801 #endif
802 	case PTRACE_SYSCALL:
803 	case PTRACE_CONT:
804 		return ptrace_resume(child, request, data);
805 
806 	case PTRACE_KILL:
807 		if (child->exit_state)	/* already dead */
808 			return 0;
809 		return ptrace_resume(child, request, SIGKILL);
810 
811 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
812 	case PTRACE_GETREGSET:
813 	case PTRACE_SETREGSET:
814 	{
815 		struct iovec kiov;
816 		struct iovec __user *uiov = datavp;
817 
818 		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
819 			return -EFAULT;
820 
821 		if (__get_user(kiov.iov_base, &uiov->iov_base) ||
822 		    __get_user(kiov.iov_len, &uiov->iov_len))
823 			return -EFAULT;
824 
825 		ret = ptrace_regset(child, request, addr, &kiov);
826 		if (!ret)
827 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
828 		break;
829 	}
830 #endif
831 	default:
832 		break;
833 	}
834 
835 	return ret;
836 }
837 
838 static struct task_struct *ptrace_get_task_struct(pid_t pid)
839 {
840 	struct task_struct *child;
841 
842 	rcu_read_lock();
843 	child = find_task_by_vpid(pid);
844 	if (child)
845 		get_task_struct(child);
846 	rcu_read_unlock();
847 
848 	if (!child)
849 		return ERR_PTR(-ESRCH);
850 	return child;
851 }
852 
853 #ifndef arch_ptrace_attach
854 #define arch_ptrace_attach(child)	do { } while (0)
855 #endif
856 
857 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
858 		unsigned long, data)
859 {
860 	struct task_struct *child;
861 	long ret;
862 
863 	if (request == PTRACE_TRACEME) {
864 		ret = ptrace_traceme();
865 		if (!ret)
866 			arch_ptrace_attach(current);
867 		goto out;
868 	}
869 
870 	child = ptrace_get_task_struct(pid);
871 	if (IS_ERR(child)) {
872 		ret = PTR_ERR(child);
873 		goto out;
874 	}
875 
876 	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
877 		ret = ptrace_attach(child, request, addr, data);
878 		/*
879 		 * Some architectures need to do book-keeping after
880 		 * a ptrace attach.
881 		 */
882 		if (!ret)
883 			arch_ptrace_attach(child);
884 		goto out_put_task_struct;
885 	}
886 
887 	ret = ptrace_check_attach(child, request == PTRACE_KILL ||
888 				  request == PTRACE_INTERRUPT);
889 	if (ret < 0)
890 		goto out_put_task_struct;
891 
892 	ret = arch_ptrace(child, request, addr, data);
893 
894  out_put_task_struct:
895 	put_task_struct(child);
896  out:
897 	return ret;
898 }
899 
900 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
901 			    unsigned long data)
902 {
903 	unsigned long tmp;
904 	int copied;
905 
906 	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
907 	if (copied != sizeof(tmp))
908 		return -EIO;
909 	return put_user(tmp, (unsigned long __user *)data);
910 }
911 
912 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
913 			    unsigned long data)
914 {
915 	int copied;
916 
917 	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
918 	return (copied == sizeof(data)) ? 0 : -EIO;
919 }
920 
921 #if defined CONFIG_COMPAT
922 #include <linux/compat.h>
923 
924 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
925 			  compat_ulong_t addr, compat_ulong_t data)
926 {
927 	compat_ulong_t __user *datap = compat_ptr(data);
928 	compat_ulong_t word;
929 	siginfo_t siginfo;
930 	int ret;
931 
932 	switch (request) {
933 	case PTRACE_PEEKTEXT:
934 	case PTRACE_PEEKDATA:
935 		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
936 		if (ret != sizeof(word))
937 			ret = -EIO;
938 		else
939 			ret = put_user(word, datap);
940 		break;
941 
942 	case PTRACE_POKETEXT:
943 	case PTRACE_POKEDATA:
944 		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
945 		ret = (ret != sizeof(data) ? -EIO : 0);
946 		break;
947 
948 	case PTRACE_GETEVENTMSG:
949 		ret = put_user((compat_ulong_t) child->ptrace_message, datap);
950 		break;
951 
952 	case PTRACE_GETSIGINFO:
953 		ret = ptrace_getsiginfo(child, &siginfo);
954 		if (!ret)
955 			ret = copy_siginfo_to_user32(
956 				(struct compat_siginfo __user *) datap,
957 				&siginfo);
958 		break;
959 
960 	case PTRACE_SETSIGINFO:
961 		memset(&siginfo, 0, sizeof siginfo);
962 		if (copy_siginfo_from_user32(
963 			    &siginfo, (struct compat_siginfo __user *) datap))
964 			ret = -EFAULT;
965 		else
966 			ret = ptrace_setsiginfo(child, &siginfo);
967 		break;
968 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
969 	case PTRACE_GETREGSET:
970 	case PTRACE_SETREGSET:
971 	{
972 		struct iovec kiov;
973 		struct compat_iovec __user *uiov =
974 			(struct compat_iovec __user *) datap;
975 		compat_uptr_t ptr;
976 		compat_size_t len;
977 
978 		if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
979 			return -EFAULT;
980 
981 		if (__get_user(ptr, &uiov->iov_base) ||
982 		    __get_user(len, &uiov->iov_len))
983 			return -EFAULT;
984 
985 		kiov.iov_base = compat_ptr(ptr);
986 		kiov.iov_len = len;
987 
988 		ret = ptrace_regset(child, request, addr, &kiov);
989 		if (!ret)
990 			ret = __put_user(kiov.iov_len, &uiov->iov_len);
991 		break;
992 	}
993 #endif
994 
995 	default:
996 		ret = ptrace_request(child, request, addr, data);
997 	}
998 
999 	return ret;
1000 }
1001 
1002 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
1003 				  compat_long_t addr, compat_long_t data)
1004 {
1005 	struct task_struct *child;
1006 	long ret;
1007 
1008 	if (request == PTRACE_TRACEME) {
1009 		ret = ptrace_traceme();
1010 		goto out;
1011 	}
1012 
1013 	child = ptrace_get_task_struct(pid);
1014 	if (IS_ERR(child)) {
1015 		ret = PTR_ERR(child);
1016 		goto out;
1017 	}
1018 
1019 	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1020 		ret = ptrace_attach(child, request, addr, data);
1021 		/*
1022 		 * Some architectures need to do book-keeping after
1023 		 * a ptrace attach.
1024 		 */
1025 		if (!ret)
1026 			arch_ptrace_attach(child);
1027 		goto out_put_task_struct;
1028 	}
1029 
1030 	ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1031 				  request == PTRACE_INTERRUPT);
1032 	if (!ret)
1033 		ret = compat_arch_ptrace(child, request, addr, data);
1034 
1035  out_put_task_struct:
1036 	put_task_struct(child);
1037  out:
1038 	return ret;
1039 }
1040 #endif	/* CONFIG_COMPAT */
1041 
1042 #ifdef CONFIG_HAVE_HW_BREAKPOINT
1043 int ptrace_get_breakpoints(struct task_struct *tsk)
1044 {
1045 	if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
1046 		return 0;
1047 
1048 	return -1;
1049 }
1050 
1051 void ptrace_put_breakpoints(struct task_struct *tsk)
1052 {
1053 	if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
1054 		flush_ptrace_hw_breakpoint(tsk);
1055 }
1056 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
1057