ptrace: use safer wake up on ptrace_detach()
[linux-2.6.git] / kernel / ptrace.c
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->signal->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->signal->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_state(child, TASK_TRACED | TASK_STOPPED);
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. Called with tasklist held
328  * for writing, and returns with it held too. But note it can release
329  * and reacquire the lock.
330  */
331 void exit_ptrace(struct task_struct *tracer)
332         __releases(&tasklist_lock)
333         __acquires(&tasklist_lock)
334 {
335         struct task_struct *p, *n;
336         LIST_HEAD(ptrace_dead);
337
338         if (likely(list_empty(&tracer->ptraced)))
339                 return;
340
341         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
342                 if (__ptrace_detach(tracer, p))
343                         list_add(&p->ptrace_entry, &ptrace_dead);
344         }
345
346         write_unlock_irq(&tasklist_lock);
347         BUG_ON(!list_empty(&tracer->ptraced));
348
349         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
350                 list_del_init(&p->ptrace_entry);
351                 release_task(p);
352         }
353
354         write_lock_irq(&tasklist_lock);
355 }
356
357 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
358 {
359         int copied = 0;
360
361         while (len > 0) {
362                 char buf[128];
363                 int this_len, retval;
364
365                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
366                 retval = access_process_vm(tsk, src, buf, this_len, 0);
367                 if (!retval) {
368                         if (copied)
369                                 break;
370                         return -EIO;
371                 }
372                 if (copy_to_user(dst, buf, retval))
373                         return -EFAULT;
374                 copied += retval;
375                 src += retval;
376                 dst += retval;
377                 len -= retval;
378         }
379         return copied;
380 }
381
382 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
383 {
384         int copied = 0;
385
386         while (len > 0) {
387                 char buf[128];
388                 int this_len, retval;
389
390                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
391                 if (copy_from_user(buf, src, this_len))
392                         return -EFAULT;
393                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
394                 if (!retval) {
395                         if (copied)
396                                 break;
397                         return -EIO;
398                 }
399                 copied += retval;
400                 src += retval;
401                 dst += retval;
402                 len -= retval;
403         }
404         return copied;
405 }
406
407 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
408 {
409         child->ptrace &= ~PT_TRACE_MASK;
410
411         if (data & PTRACE_O_TRACESYSGOOD)
412                 child->ptrace |= PT_TRACESYSGOOD;
413
414         if (data & PTRACE_O_TRACEFORK)
415                 child->ptrace |= PT_TRACE_FORK;
416
417         if (data & PTRACE_O_TRACEVFORK)
418                 child->ptrace |= PT_TRACE_VFORK;
419
420         if (data & PTRACE_O_TRACECLONE)
421                 child->ptrace |= PT_TRACE_CLONE;
422
423         if (data & PTRACE_O_TRACEEXEC)
424                 child->ptrace |= PT_TRACE_EXEC;
425
426         if (data & PTRACE_O_TRACEVFORKDONE)
427                 child->ptrace |= PT_TRACE_VFORK_DONE;
428
429         if (data & PTRACE_O_TRACEEXIT)
430                 child->ptrace |= PT_TRACE_EXIT;
431
432         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
433 }
434
435 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
436 {
437         unsigned long flags;
438         int error = -ESRCH;
439
440         if (lock_task_sighand(child, &flags)) {
441                 error = -EINVAL;
442                 if (likely(child->last_siginfo != NULL)) {
443                         *info = *child->last_siginfo;
444                         error = 0;
445                 }
446                 unlock_task_sighand(child, &flags);
447         }
448         return error;
449 }
450
451 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
452 {
453         unsigned long flags;
454         int error = -ESRCH;
455
456         if (lock_task_sighand(child, &flags)) {
457                 error = -EINVAL;
458                 if (likely(child->last_siginfo != NULL)) {
459                         *child->last_siginfo = *info;
460                         error = 0;
461                 }
462                 unlock_task_sighand(child, &flags);
463         }
464         return error;
465 }
466
467
468 #ifdef PTRACE_SINGLESTEP
469 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
470 #else
471 #define is_singlestep(request)          0
472 #endif
473
474 #ifdef PTRACE_SINGLEBLOCK
475 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
476 #else
477 #define is_singleblock(request)         0
478 #endif
479
480 #ifdef PTRACE_SYSEMU
481 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
482 #else
483 #define is_sysemu_singlestep(request)   0
484 #endif
485
486 static int ptrace_resume(struct task_struct *child, long request,
487                          unsigned long data)
488 {
489         if (!valid_signal(data))
490                 return -EIO;
491
492         if (request == PTRACE_SYSCALL)
493                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
494         else
495                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
496
497 #ifdef TIF_SYSCALL_EMU
498         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
499                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
500         else
501                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
502 #endif
503
504         if (is_singleblock(request)) {
505                 if (unlikely(!arch_has_block_step()))
506                         return -EIO;
507                 user_enable_block_step(child);
508         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
509                 if (unlikely(!arch_has_single_step()))
510                         return -EIO;
511                 user_enable_single_step(child);
512         } else {
513                 user_disable_single_step(child);
514         }
515
516         child->exit_code = data;
517         wake_up_process(child);
518
519         return 0;
520 }
521
522 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
523
524 static const struct user_regset *
525 find_regset(const struct user_regset_view *view, unsigned int type)
526 {
527         const struct user_regset *regset;
528         int n;
529
530         for (n = 0; n < view->n; ++n) {
531                 regset = view->regsets + n;
532                 if (regset->core_note_type == type)
533                         return regset;
534         }
535
536         return NULL;
537 }
538
539 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
540                          struct iovec *kiov)
541 {
542         const struct user_regset_view *view = task_user_regset_view(task);
543         const struct user_regset *regset = find_regset(view, type);
544         int regset_no;
545
546         if (!regset || (kiov->iov_len % regset->size) != 0)
547                 return -EINVAL;
548
549         regset_no = regset - view->regsets;
550         kiov->iov_len = min(kiov->iov_len,
551                             (__kernel_size_t) (regset->n * regset->size));
552
553         if (req == PTRACE_GETREGSET)
554                 return copy_regset_to_user(task, view, regset_no, 0,
555                                            kiov->iov_len, kiov->iov_base);
556         else
557                 return copy_regset_from_user(task, view, regset_no, 0,
558                                              kiov->iov_len, kiov->iov_base);
559 }
560
561 #endif
562
563 int ptrace_request(struct task_struct *child, long request,
564                    unsigned long addr, unsigned long data)
565 {
566         int ret = -EIO;
567         siginfo_t siginfo;
568         void __user *datavp = (void __user *) data;
569         unsigned long __user *datalp = datavp;
570
571         switch (request) {
572         case PTRACE_PEEKTEXT:
573         case PTRACE_PEEKDATA:
574                 return generic_ptrace_peekdata(child, addr, data);
575         case PTRACE_POKETEXT:
576         case PTRACE_POKEDATA:
577                 return generic_ptrace_pokedata(child, addr, data);
578
579 #ifdef PTRACE_OLDSETOPTIONS
580         case PTRACE_OLDSETOPTIONS:
581 #endif
582         case PTRACE_SETOPTIONS:
583                 ret = ptrace_setoptions(child, data);
584                 break;
585         case PTRACE_GETEVENTMSG:
586                 ret = put_user(child->ptrace_message, datalp);
587                 break;
588
589         case PTRACE_GETSIGINFO:
590                 ret = ptrace_getsiginfo(child, &siginfo);
591                 if (!ret)
592                         ret = copy_siginfo_to_user(datavp, &siginfo);
593                 break;
594
595         case PTRACE_SETSIGINFO:
596                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
597                         ret = -EFAULT;
598                 else
599                         ret = ptrace_setsiginfo(child, &siginfo);
600                 break;
601
602         case PTRACE_DETACH:      /* detach a process that was attached. */
603                 ret = ptrace_detach(child, data);
604                 break;
605
606 #ifdef CONFIG_BINFMT_ELF_FDPIC
607         case PTRACE_GETFDPIC: {
608                 struct mm_struct *mm = get_task_mm(child);
609                 unsigned long tmp = 0;
610
611                 ret = -ESRCH;
612                 if (!mm)
613                         break;
614
615                 switch (addr) {
616                 case PTRACE_GETFDPIC_EXEC:
617                         tmp = mm->context.exec_fdpic_loadmap;
618                         break;
619                 case PTRACE_GETFDPIC_INTERP:
620                         tmp = mm->context.interp_fdpic_loadmap;
621                         break;
622                 default:
623                         break;
624                 }
625                 mmput(mm);
626
627                 ret = put_user(tmp, datalp);
628                 break;
629         }
630 #endif
631
632 #ifdef PTRACE_SINGLESTEP
633         case PTRACE_SINGLESTEP:
634 #endif
635 #ifdef PTRACE_SINGLEBLOCK
636         case PTRACE_SINGLEBLOCK:
637 #endif
638 #ifdef PTRACE_SYSEMU
639         case PTRACE_SYSEMU:
640         case PTRACE_SYSEMU_SINGLESTEP:
641 #endif
642         case PTRACE_SYSCALL:
643         case PTRACE_CONT:
644                 return ptrace_resume(child, request, data);
645
646         case PTRACE_KILL:
647                 if (child->exit_state)  /* already dead */
648                         return 0;
649                 return ptrace_resume(child, request, SIGKILL);
650
651 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
652         case PTRACE_GETREGSET:
653         case PTRACE_SETREGSET:
654         {
655                 struct iovec kiov;
656                 struct iovec __user *uiov = datavp;
657
658                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
659                         return -EFAULT;
660
661                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
662                     __get_user(kiov.iov_len, &uiov->iov_len))
663                         return -EFAULT;
664
665                 ret = ptrace_regset(child, request, addr, &kiov);
666                 if (!ret)
667                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
668                 break;
669         }
670 #endif
671         default:
672                 break;
673         }
674
675         return ret;
676 }
677
678 static struct task_struct *ptrace_get_task_struct(pid_t pid)
679 {
680         struct task_struct *child;
681
682         rcu_read_lock();
683         child = find_task_by_vpid(pid);
684         if (child)
685                 get_task_struct(child);
686         rcu_read_unlock();
687
688         if (!child)
689                 return ERR_PTR(-ESRCH);
690         return child;
691 }
692
693 #ifndef arch_ptrace_attach
694 #define arch_ptrace_attach(child)       do { } while (0)
695 #endif
696
697 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
698                 unsigned long, data)
699 {
700         struct task_struct *child;
701         long ret;
702
703         if (request == PTRACE_TRACEME) {
704                 ret = ptrace_traceme();
705                 if (!ret)
706                         arch_ptrace_attach(current);
707                 goto out;
708         }
709
710         child = ptrace_get_task_struct(pid);
711         if (IS_ERR(child)) {
712                 ret = PTR_ERR(child);
713                 goto out;
714         }
715
716         if (request == PTRACE_ATTACH) {
717                 ret = ptrace_attach(child);
718                 /*
719                  * Some architectures need to do book-keeping after
720                  * a ptrace attach.
721                  */
722                 if (!ret)
723                         arch_ptrace_attach(child);
724                 goto out_put_task_struct;
725         }
726
727         ret = ptrace_check_attach(child, request == PTRACE_KILL);
728         if (ret < 0)
729                 goto out_put_task_struct;
730
731         ret = arch_ptrace(child, request, addr, data);
732
733  out_put_task_struct:
734         put_task_struct(child);
735  out:
736         return ret;
737 }
738
739 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
740                             unsigned long data)
741 {
742         unsigned long tmp;
743         int copied;
744
745         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
746         if (copied != sizeof(tmp))
747                 return -EIO;
748         return put_user(tmp, (unsigned long __user *)data);
749 }
750
751 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
752                             unsigned long data)
753 {
754         int copied;
755
756         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
757         return (copied == sizeof(data)) ? 0 : -EIO;
758 }
759
760 #if defined CONFIG_COMPAT
761 #include <linux/compat.h>
762
763 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
764                           compat_ulong_t addr, compat_ulong_t data)
765 {
766         compat_ulong_t __user *datap = compat_ptr(data);
767         compat_ulong_t word;
768         siginfo_t siginfo;
769         int ret;
770
771         switch (request) {
772         case PTRACE_PEEKTEXT:
773         case PTRACE_PEEKDATA:
774                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
775                 if (ret != sizeof(word))
776                         ret = -EIO;
777                 else
778                         ret = put_user(word, datap);
779                 break;
780
781         case PTRACE_POKETEXT:
782         case PTRACE_POKEDATA:
783                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
784                 ret = (ret != sizeof(data) ? -EIO : 0);
785                 break;
786
787         case PTRACE_GETEVENTMSG:
788                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
789                 break;
790
791         case PTRACE_GETSIGINFO:
792                 ret = ptrace_getsiginfo(child, &siginfo);
793                 if (!ret)
794                         ret = copy_siginfo_to_user32(
795                                 (struct compat_siginfo __user *) datap,
796                                 &siginfo);
797                 break;
798
799         case PTRACE_SETSIGINFO:
800                 memset(&siginfo, 0, sizeof siginfo);
801                 if (copy_siginfo_from_user32(
802                             &siginfo, (struct compat_siginfo __user *) datap))
803                         ret = -EFAULT;
804                 else
805                         ret = ptrace_setsiginfo(child, &siginfo);
806                 break;
807 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
808         case PTRACE_GETREGSET:
809         case PTRACE_SETREGSET:
810         {
811                 struct iovec kiov;
812                 struct compat_iovec __user *uiov =
813                         (struct compat_iovec __user *) datap;
814                 compat_uptr_t ptr;
815                 compat_size_t len;
816
817                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
818                         return -EFAULT;
819
820                 if (__get_user(ptr, &uiov->iov_base) ||
821                     __get_user(len, &uiov->iov_len))
822                         return -EFAULT;
823
824                 kiov.iov_base = compat_ptr(ptr);
825                 kiov.iov_len = len;
826
827                 ret = ptrace_regset(child, request, addr, &kiov);
828                 if (!ret)
829                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
830                 break;
831         }
832 #endif
833
834         default:
835                 ret = ptrace_request(child, request, addr, data);
836         }
837
838         return ret;
839 }
840
841 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
842                                   compat_long_t addr, compat_long_t data)
843 {
844         struct task_struct *child;
845         long ret;
846
847         if (request == PTRACE_TRACEME) {
848                 ret = ptrace_traceme();
849                 goto out;
850         }
851
852         child = ptrace_get_task_struct(pid);
853         if (IS_ERR(child)) {
854                 ret = PTR_ERR(child);
855                 goto out;
856         }
857
858         if (request == PTRACE_ATTACH) {
859                 ret = ptrace_attach(child);
860                 /*
861                  * Some architectures need to do book-keeping after
862                  * a ptrace attach.
863                  */
864                 if (!ret)
865                         arch_ptrace_attach(child);
866                 goto out_put_task_struct;
867         }
868
869         ret = ptrace_check_attach(child, request == PTRACE_KILL);
870         if (!ret)
871                 ret = compat_arch_ptrace(child, request, addr, data);
872
873  out_put_task_struct:
874         put_task_struct(child);
875  out:
876         return ret;
877 }
878 #endif  /* CONFIG_COMPAT */