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