ptrace: Remove the extra wake_up_state() from 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 static 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 static 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 static 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         }
316         write_unlock_irq(&tasklist_lock);
317
318         if (unlikely(dead))
319                 release_task(child);
320
321         return 0;
322 }
323
324 /*
325  * Detach all tasks we were using ptrace on. Called with tasklist held
326  * for writing, and returns with it held too. But note it can release
327  * and reacquire the lock.
328  */
329 void exit_ptrace(struct task_struct *tracer)
330         __releases(&tasklist_lock)
331         __acquires(&tasklist_lock)
332 {
333         struct task_struct *p, *n;
334         LIST_HEAD(ptrace_dead);
335
336         if (likely(list_empty(&tracer->ptraced)))
337                 return;
338
339         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
340                 if (__ptrace_detach(tracer, p))
341                         list_add(&p->ptrace_entry, &ptrace_dead);
342         }
343
344         write_unlock_irq(&tasklist_lock);
345         BUG_ON(!list_empty(&tracer->ptraced));
346
347         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
348                 list_del_init(&p->ptrace_entry);
349                 release_task(p);
350         }
351
352         write_lock_irq(&tasklist_lock);
353 }
354
355 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
356 {
357         int copied = 0;
358
359         while (len > 0) {
360                 char buf[128];
361                 int this_len, retval;
362
363                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
364                 retval = access_process_vm(tsk, src, buf, this_len, 0);
365                 if (!retval) {
366                         if (copied)
367                                 break;
368                         return -EIO;
369                 }
370                 if (copy_to_user(dst, buf, retval))
371                         return -EFAULT;
372                 copied += retval;
373                 src += retval;
374                 dst += retval;
375                 len -= retval;
376         }
377         return copied;
378 }
379
380 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
381 {
382         int copied = 0;
383
384         while (len > 0) {
385                 char buf[128];
386                 int this_len, retval;
387
388                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
389                 if (copy_from_user(buf, src, this_len))
390                         return -EFAULT;
391                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
392                 if (!retval) {
393                         if (copied)
394                                 break;
395                         return -EIO;
396                 }
397                 copied += retval;
398                 src += retval;
399                 dst += retval;
400                 len -= retval;
401         }
402         return copied;
403 }
404
405 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
406 {
407         child->ptrace &= ~PT_TRACE_MASK;
408
409         if (data & PTRACE_O_TRACESYSGOOD)
410                 child->ptrace |= PT_TRACESYSGOOD;
411
412         if (data & PTRACE_O_TRACEFORK)
413                 child->ptrace |= PT_TRACE_FORK;
414
415         if (data & PTRACE_O_TRACEVFORK)
416                 child->ptrace |= PT_TRACE_VFORK;
417
418         if (data & PTRACE_O_TRACECLONE)
419                 child->ptrace |= PT_TRACE_CLONE;
420
421         if (data & PTRACE_O_TRACEEXEC)
422                 child->ptrace |= PT_TRACE_EXEC;
423
424         if (data & PTRACE_O_TRACEVFORKDONE)
425                 child->ptrace |= PT_TRACE_VFORK_DONE;
426
427         if (data & PTRACE_O_TRACEEXIT)
428                 child->ptrace |= PT_TRACE_EXIT;
429
430         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
431 }
432
433 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
434 {
435         unsigned long flags;
436         int error = -ESRCH;
437
438         if (lock_task_sighand(child, &flags)) {
439                 error = -EINVAL;
440                 if (likely(child->last_siginfo != NULL)) {
441                         *info = *child->last_siginfo;
442                         error = 0;
443                 }
444                 unlock_task_sighand(child, &flags);
445         }
446         return error;
447 }
448
449 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
450 {
451         unsigned long flags;
452         int error = -ESRCH;
453
454         if (lock_task_sighand(child, &flags)) {
455                 error = -EINVAL;
456                 if (likely(child->last_siginfo != NULL)) {
457                         *child->last_siginfo = *info;
458                         error = 0;
459                 }
460                 unlock_task_sighand(child, &flags);
461         }
462         return error;
463 }
464
465
466 #ifdef PTRACE_SINGLESTEP
467 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
468 #else
469 #define is_singlestep(request)          0
470 #endif
471
472 #ifdef PTRACE_SINGLEBLOCK
473 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
474 #else
475 #define is_singleblock(request)         0
476 #endif
477
478 #ifdef PTRACE_SYSEMU
479 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
480 #else
481 #define is_sysemu_singlestep(request)   0
482 #endif
483
484 static int ptrace_resume(struct task_struct *child, long request,
485                          unsigned long data)
486 {
487         if (!valid_signal(data))
488                 return -EIO;
489
490         if (request == PTRACE_SYSCALL)
491                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
492         else
493                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
494
495 #ifdef TIF_SYSCALL_EMU
496         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
497                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
498         else
499                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
500 #endif
501
502         if (is_singleblock(request)) {
503                 if (unlikely(!arch_has_block_step()))
504                         return -EIO;
505                 user_enable_block_step(child);
506         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
507                 if (unlikely(!arch_has_single_step()))
508                         return -EIO;
509                 user_enable_single_step(child);
510         } else {
511                 user_disable_single_step(child);
512         }
513
514         child->exit_code = data;
515         wake_up_process(child);
516
517         return 0;
518 }
519
520 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
521
522 static const struct user_regset *
523 find_regset(const struct user_regset_view *view, unsigned int type)
524 {
525         const struct user_regset *regset;
526         int n;
527
528         for (n = 0; n < view->n; ++n) {
529                 regset = view->regsets + n;
530                 if (regset->core_note_type == type)
531                         return regset;
532         }
533
534         return NULL;
535 }
536
537 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
538                          struct iovec *kiov)
539 {
540         const struct user_regset_view *view = task_user_regset_view(task);
541         const struct user_regset *regset = find_regset(view, type);
542         int regset_no;
543
544         if (!regset || (kiov->iov_len % regset->size) != 0)
545                 return -EINVAL;
546
547         regset_no = regset - view->regsets;
548         kiov->iov_len = min(kiov->iov_len,
549                             (__kernel_size_t) (regset->n * regset->size));
550
551         if (req == PTRACE_GETREGSET)
552                 return copy_regset_to_user(task, view, regset_no, 0,
553                                            kiov->iov_len, kiov->iov_base);
554         else
555                 return copy_regset_from_user(task, view, regset_no, 0,
556                                              kiov->iov_len, kiov->iov_base);
557 }
558
559 #endif
560
561 int ptrace_request(struct task_struct *child, long request,
562                    unsigned long addr, unsigned long data)
563 {
564         int ret = -EIO;
565         siginfo_t siginfo;
566         void __user *datavp = (void __user *) data;
567         unsigned long __user *datalp = datavp;
568
569         switch (request) {
570         case PTRACE_PEEKTEXT:
571         case PTRACE_PEEKDATA:
572                 return generic_ptrace_peekdata(child, addr, data);
573         case PTRACE_POKETEXT:
574         case PTRACE_POKEDATA:
575                 return generic_ptrace_pokedata(child, addr, data);
576
577 #ifdef PTRACE_OLDSETOPTIONS
578         case PTRACE_OLDSETOPTIONS:
579 #endif
580         case PTRACE_SETOPTIONS:
581                 ret = ptrace_setoptions(child, data);
582                 break;
583         case PTRACE_GETEVENTMSG:
584                 ret = put_user(child->ptrace_message, datalp);
585                 break;
586
587         case PTRACE_GETSIGINFO:
588                 ret = ptrace_getsiginfo(child, &siginfo);
589                 if (!ret)
590                         ret = copy_siginfo_to_user(datavp, &siginfo);
591                 break;
592
593         case PTRACE_SETSIGINFO:
594                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
595                         ret = -EFAULT;
596                 else
597                         ret = ptrace_setsiginfo(child, &siginfo);
598                 break;
599
600         case PTRACE_DETACH:      /* detach a process that was attached. */
601                 ret = ptrace_detach(child, data);
602                 break;
603
604 #ifdef CONFIG_BINFMT_ELF_FDPIC
605         case PTRACE_GETFDPIC: {
606                 struct mm_struct *mm = get_task_mm(child);
607                 unsigned long tmp = 0;
608
609                 ret = -ESRCH;
610                 if (!mm)
611                         break;
612
613                 switch (addr) {
614                 case PTRACE_GETFDPIC_EXEC:
615                         tmp = mm->context.exec_fdpic_loadmap;
616                         break;
617                 case PTRACE_GETFDPIC_INTERP:
618                         tmp = mm->context.interp_fdpic_loadmap;
619                         break;
620                 default:
621                         break;
622                 }
623                 mmput(mm);
624
625                 ret = put_user(tmp, datalp);
626                 break;
627         }
628 #endif
629
630 #ifdef PTRACE_SINGLESTEP
631         case PTRACE_SINGLESTEP:
632 #endif
633 #ifdef PTRACE_SINGLEBLOCK
634         case PTRACE_SINGLEBLOCK:
635 #endif
636 #ifdef PTRACE_SYSEMU
637         case PTRACE_SYSEMU:
638         case PTRACE_SYSEMU_SINGLESTEP:
639 #endif
640         case PTRACE_SYSCALL:
641         case PTRACE_CONT:
642                 return ptrace_resume(child, request, data);
643
644         case PTRACE_KILL:
645                 if (child->exit_state)  /* already dead */
646                         return 0;
647                 return ptrace_resume(child, request, SIGKILL);
648
649 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
650         case PTRACE_GETREGSET:
651         case PTRACE_SETREGSET:
652         {
653                 struct iovec kiov;
654                 struct iovec __user *uiov = datavp;
655
656                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
657                         return -EFAULT;
658
659                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
660                     __get_user(kiov.iov_len, &uiov->iov_len))
661                         return -EFAULT;
662
663                 ret = ptrace_regset(child, request, addr, &kiov);
664                 if (!ret)
665                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
666                 break;
667         }
668 #endif
669         default:
670                 break;
671         }
672
673         return ret;
674 }
675
676 static struct task_struct *ptrace_get_task_struct(pid_t pid)
677 {
678         struct task_struct *child;
679
680         rcu_read_lock();
681         child = find_task_by_vpid(pid);
682         if (child)
683                 get_task_struct(child);
684         rcu_read_unlock();
685
686         if (!child)
687                 return ERR_PTR(-ESRCH);
688         return child;
689 }
690
691 #ifndef arch_ptrace_attach
692 #define arch_ptrace_attach(child)       do { } while (0)
693 #endif
694
695 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
696                 unsigned long, data)
697 {
698         struct task_struct *child;
699         long ret;
700
701         if (request == PTRACE_TRACEME) {
702                 ret = ptrace_traceme();
703                 if (!ret)
704                         arch_ptrace_attach(current);
705                 goto out;
706         }
707
708         child = ptrace_get_task_struct(pid);
709         if (IS_ERR(child)) {
710                 ret = PTR_ERR(child);
711                 goto out;
712         }
713
714         if (request == PTRACE_ATTACH) {
715                 ret = ptrace_attach(child);
716                 /*
717                  * Some architectures need to do book-keeping after
718                  * a ptrace attach.
719                  */
720                 if (!ret)
721                         arch_ptrace_attach(child);
722                 goto out_put_task_struct;
723         }
724
725         ret = ptrace_check_attach(child, request == PTRACE_KILL);
726         if (ret < 0)
727                 goto out_put_task_struct;
728
729         ret = arch_ptrace(child, request, addr, data);
730
731  out_put_task_struct:
732         put_task_struct(child);
733  out:
734         return ret;
735 }
736
737 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
738                             unsigned long data)
739 {
740         unsigned long tmp;
741         int copied;
742
743         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
744         if (copied != sizeof(tmp))
745                 return -EIO;
746         return put_user(tmp, (unsigned long __user *)data);
747 }
748
749 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
750                             unsigned long data)
751 {
752         int copied;
753
754         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
755         return (copied == sizeof(data)) ? 0 : -EIO;
756 }
757
758 #if defined CONFIG_COMPAT
759 #include <linux/compat.h>
760
761 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
762                           compat_ulong_t addr, compat_ulong_t data)
763 {
764         compat_ulong_t __user *datap = compat_ptr(data);
765         compat_ulong_t word;
766         siginfo_t siginfo;
767         int ret;
768
769         switch (request) {
770         case PTRACE_PEEKTEXT:
771         case PTRACE_PEEKDATA:
772                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
773                 if (ret != sizeof(word))
774                         ret = -EIO;
775                 else
776                         ret = put_user(word, datap);
777                 break;
778
779         case PTRACE_POKETEXT:
780         case PTRACE_POKEDATA:
781                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
782                 ret = (ret != sizeof(data) ? -EIO : 0);
783                 break;
784
785         case PTRACE_GETEVENTMSG:
786                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
787                 break;
788
789         case PTRACE_GETSIGINFO:
790                 ret = ptrace_getsiginfo(child, &siginfo);
791                 if (!ret)
792                         ret = copy_siginfo_to_user32(
793                                 (struct compat_siginfo __user *) datap,
794                                 &siginfo);
795                 break;
796
797         case PTRACE_SETSIGINFO:
798                 memset(&siginfo, 0, sizeof siginfo);
799                 if (copy_siginfo_from_user32(
800                             &siginfo, (struct compat_siginfo __user *) datap))
801                         ret = -EFAULT;
802                 else
803                         ret = ptrace_setsiginfo(child, &siginfo);
804                 break;
805 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
806         case PTRACE_GETREGSET:
807         case PTRACE_SETREGSET:
808         {
809                 struct iovec kiov;
810                 struct compat_iovec __user *uiov =
811                         (struct compat_iovec __user *) datap;
812                 compat_uptr_t ptr;
813                 compat_size_t len;
814
815                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
816                         return -EFAULT;
817
818                 if (__get_user(ptr, &uiov->iov_base) ||
819                     __get_user(len, &uiov->iov_len))
820                         return -EFAULT;
821
822                 kiov.iov_base = compat_ptr(ptr);
823                 kiov.iov_len = len;
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
832         default:
833                 ret = ptrace_request(child, request, addr, data);
834         }
835
836         return ret;
837 }
838
839 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
840                                   compat_long_t addr, compat_long_t data)
841 {
842         struct task_struct *child;
843         long ret;
844
845         if (request == PTRACE_TRACEME) {
846                 ret = ptrace_traceme();
847                 goto out;
848         }
849
850         child = ptrace_get_task_struct(pid);
851         if (IS_ERR(child)) {
852                 ret = PTR_ERR(child);
853                 goto out;
854         }
855
856         if (request == PTRACE_ATTACH) {
857                 ret = ptrace_attach(child);
858                 /*
859                  * Some architectures need to do book-keeping after
860                  * a ptrace attach.
861                  */
862                 if (!ret)
863                         arch_ptrace_attach(child);
864                 goto out_put_task_struct;
865         }
866
867         ret = ptrace_check_attach(child, request == PTRACE_KILL);
868         if (!ret)
869                 ret = compat_arch_ptrace(child, request, addr, data);
870
871  out_put_task_struct:
872         put_task_struct(child);
873  out:
874         return ret;
875 }
876 #endif  /* CONFIG_COMPAT */