umh: creds: convert call_usermodehelper_keys() to use subprocess_info->init()
[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->cred_guard_mutex))
185                 goto out;
186
187         task_lock(task);
188         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
189         task_unlock(task);
190         if (retval)
191                 goto unlock_creds;
192
193         write_lock_irq(&tasklist_lock);
194         retval = -EPERM;
195         if (unlikely(task->exit_state))
196                 goto unlock_tasklist;
197         if (task->ptrace)
198                 goto unlock_tasklist;
199
200         task->ptrace = PT_PTRACED;
201         if (capable(CAP_SYS_PTRACE))
202                 task->ptrace |= PT_PTRACE_CAP;
203
204         __ptrace_link(task, current);
205         send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
206
207         retval = 0;
208 unlock_tasklist:
209         write_unlock_irq(&tasklist_lock);
210 unlock_creds:
211         mutex_unlock(&task->cred_guard_mutex);
212 out:
213         return retval;
214 }
215
216 /**
217  * ptrace_traceme  --  helper for PTRACE_TRACEME
218  *
219  * Performs checks and sets PT_PTRACED.
220  * Should be used by all ptrace implementations for PTRACE_TRACEME.
221  */
222 int ptrace_traceme(void)
223 {
224         int ret = -EPERM;
225
226         write_lock_irq(&tasklist_lock);
227         /* Are we already being traced? */
228         if (!current->ptrace) {
229                 ret = security_ptrace_traceme(current->parent);
230                 /*
231                  * Check PF_EXITING to ensure ->real_parent has not passed
232                  * exit_ptrace(). Otherwise we don't report the error but
233                  * pretend ->real_parent untraces us right after return.
234                  */
235                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
236                         current->ptrace = PT_PTRACED;
237                         __ptrace_link(current, current->real_parent);
238                 }
239         }
240         write_unlock_irq(&tasklist_lock);
241
242         return ret;
243 }
244
245 /*
246  * Called with irqs disabled, returns true if childs should reap themselves.
247  */
248 static int ignoring_children(struct sighand_struct *sigh)
249 {
250         int ret;
251         spin_lock(&sigh->siglock);
252         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
253               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
254         spin_unlock(&sigh->siglock);
255         return ret;
256 }
257
258 /*
259  * Called with tasklist_lock held for writing.
260  * Unlink a traced task, and clean it up if it was a traced zombie.
261  * Return true if it needs to be reaped with release_task().
262  * (We can't call release_task() here because we already hold tasklist_lock.)
263  *
264  * If it's a zombie, our attachedness prevented normal parent notification
265  * or self-reaping.  Do notification now if it would have happened earlier.
266  * If it should reap itself, return true.
267  *
268  * If it's our own child, there is no notification to do. But if our normal
269  * children self-reap, then this child was prevented by ptrace and we must
270  * reap it now, in that case we must also wake up sub-threads sleeping in
271  * do_wait().
272  */
273 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
274 {
275         __ptrace_unlink(p);
276
277         if (p->exit_state == EXIT_ZOMBIE) {
278                 if (!task_detached(p) && thread_group_empty(p)) {
279                         if (!same_thread_group(p->real_parent, tracer))
280                                 do_notify_parent(p, p->exit_signal);
281                         else if (ignoring_children(tracer->sighand)) {
282                                 __wake_up_parent(p, tracer);
283                                 p->exit_signal = -1;
284                         }
285                 }
286                 if (task_detached(p)) {
287                         /* Mark it as in the process of being reaped. */
288                         p->exit_state = EXIT_DEAD;
289                         return true;
290                 }
291         }
292
293         return false;
294 }
295
296 int ptrace_detach(struct task_struct *child, unsigned int data)
297 {
298         bool dead = false;
299
300         if (!valid_signal(data))
301                 return -EIO;
302
303         /* Architecture-specific hardware disable .. */
304         ptrace_disable(child);
305         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
306
307         write_lock_irq(&tasklist_lock);
308         /*
309          * This child can be already killed. Make sure de_thread() or
310          * our sub-thread doing do_wait() didn't do release_task() yet.
311          */
312         if (child->ptrace) {
313                 child->exit_code = data;
314                 dead = __ptrace_detach(current, child);
315                 if (!child->exit_state)
316                         wake_up_process(child);
317         }
318         write_unlock_irq(&tasklist_lock);
319
320         if (unlikely(dead))
321                 release_task(child);
322
323         return 0;
324 }
325
326 /*
327  * Detach all tasks we were using ptrace on.
328  */
329 void exit_ptrace(struct task_struct *tracer)
330 {
331         struct task_struct *p, *n;
332         LIST_HEAD(ptrace_dead);
333
334         write_lock_irq(&tasklist_lock);
335         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
336                 if (__ptrace_detach(tracer, p))
337                         list_add(&p->ptrace_entry, &ptrace_dead);
338         }
339         write_unlock_irq(&tasklist_lock);
340
341         BUG_ON(!list_empty(&tracer->ptraced));
342
343         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
344                 list_del_init(&p->ptrace_entry);
345                 release_task(p);
346         }
347 }
348
349 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
350 {
351         int copied = 0;
352
353         while (len > 0) {
354                 char buf[128];
355                 int this_len, retval;
356
357                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
358                 retval = access_process_vm(tsk, src, buf, this_len, 0);
359                 if (!retval) {
360                         if (copied)
361                                 break;
362                         return -EIO;
363                 }
364                 if (copy_to_user(dst, buf, retval))
365                         return -EFAULT;
366                 copied += retval;
367                 src += retval;
368                 dst += retval;
369                 len -= retval;
370         }
371         return copied;
372 }
373
374 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
375 {
376         int copied = 0;
377
378         while (len > 0) {
379                 char buf[128];
380                 int this_len, retval;
381
382                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
383                 if (copy_from_user(buf, src, this_len))
384                         return -EFAULT;
385                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
386                 if (!retval) {
387                         if (copied)
388                                 break;
389                         return -EIO;
390                 }
391                 copied += retval;
392                 src += retval;
393                 dst += retval;
394                 len -= retval;
395         }
396         return copied;
397 }
398
399 static int ptrace_setoptions(struct task_struct *child, long data)
400 {
401         child->ptrace &= ~PT_TRACE_MASK;
402
403         if (data & PTRACE_O_TRACESYSGOOD)
404                 child->ptrace |= PT_TRACESYSGOOD;
405
406         if (data & PTRACE_O_TRACEFORK)
407                 child->ptrace |= PT_TRACE_FORK;
408
409         if (data & PTRACE_O_TRACEVFORK)
410                 child->ptrace |= PT_TRACE_VFORK;
411
412         if (data & PTRACE_O_TRACECLONE)
413                 child->ptrace |= PT_TRACE_CLONE;
414
415         if (data & PTRACE_O_TRACEEXEC)
416                 child->ptrace |= PT_TRACE_EXEC;
417
418         if (data & PTRACE_O_TRACEVFORKDONE)
419                 child->ptrace |= PT_TRACE_VFORK_DONE;
420
421         if (data & PTRACE_O_TRACEEXIT)
422                 child->ptrace |= PT_TRACE_EXIT;
423
424         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
425 }
426
427 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
428 {
429         unsigned long flags;
430         int error = -ESRCH;
431
432         if (lock_task_sighand(child, &flags)) {
433                 error = -EINVAL;
434                 if (likely(child->last_siginfo != NULL)) {
435                         *info = *child->last_siginfo;
436                         error = 0;
437                 }
438                 unlock_task_sighand(child, &flags);
439         }
440         return error;
441 }
442
443 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
444 {
445         unsigned long flags;
446         int error = -ESRCH;
447
448         if (lock_task_sighand(child, &flags)) {
449                 error = -EINVAL;
450                 if (likely(child->last_siginfo != NULL)) {
451                         *child->last_siginfo = *info;
452                         error = 0;
453                 }
454                 unlock_task_sighand(child, &flags);
455         }
456         return error;
457 }
458
459
460 #ifdef PTRACE_SINGLESTEP
461 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
462 #else
463 #define is_singlestep(request)          0
464 #endif
465
466 #ifdef PTRACE_SINGLEBLOCK
467 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
468 #else
469 #define is_singleblock(request)         0
470 #endif
471
472 #ifdef PTRACE_SYSEMU
473 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
474 #else
475 #define is_sysemu_singlestep(request)   0
476 #endif
477
478 static int ptrace_resume(struct task_struct *child, long request, long data)
479 {
480         if (!valid_signal(data))
481                 return -EIO;
482
483         if (request == PTRACE_SYSCALL)
484                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
485         else
486                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
487
488 #ifdef TIF_SYSCALL_EMU
489         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
490                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
491         else
492                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
493 #endif
494
495         if (is_singleblock(request)) {
496                 if (unlikely(!arch_has_block_step()))
497                         return -EIO;
498                 user_enable_block_step(child);
499         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
500                 if (unlikely(!arch_has_single_step()))
501                         return -EIO;
502                 user_enable_single_step(child);
503         } else {
504                 user_disable_single_step(child);
505         }
506
507         child->exit_code = data;
508         wake_up_process(child);
509
510         return 0;
511 }
512
513 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
514
515 static const struct user_regset *
516 find_regset(const struct user_regset_view *view, unsigned int type)
517 {
518         const struct user_regset *regset;
519         int n;
520
521         for (n = 0; n < view->n; ++n) {
522                 regset = view->regsets + n;
523                 if (regset->core_note_type == type)
524                         return regset;
525         }
526
527         return NULL;
528 }
529
530 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
531                          struct iovec *kiov)
532 {
533         const struct user_regset_view *view = task_user_regset_view(task);
534         const struct user_regset *regset = find_regset(view, type);
535         int regset_no;
536
537         if (!regset || (kiov->iov_len % regset->size) != 0)
538                 return -EINVAL;
539
540         regset_no = regset - view->regsets;
541         kiov->iov_len = min(kiov->iov_len,
542                             (__kernel_size_t) (regset->n * regset->size));
543
544         if (req == PTRACE_GETREGSET)
545                 return copy_regset_to_user(task, view, regset_no, 0,
546                                            kiov->iov_len, kiov->iov_base);
547         else
548                 return copy_regset_from_user(task, view, regset_no, 0,
549                                              kiov->iov_len, kiov->iov_base);
550 }
551
552 #endif
553
554 int ptrace_request(struct task_struct *child, long request,
555                    long addr, long data)
556 {
557         int ret = -EIO;
558         siginfo_t siginfo;
559
560         switch (request) {
561         case PTRACE_PEEKTEXT:
562         case PTRACE_PEEKDATA:
563                 return generic_ptrace_peekdata(child, addr, data);
564         case PTRACE_POKETEXT:
565         case PTRACE_POKEDATA:
566                 return generic_ptrace_pokedata(child, addr, data);
567
568 #ifdef PTRACE_OLDSETOPTIONS
569         case PTRACE_OLDSETOPTIONS:
570 #endif
571         case PTRACE_SETOPTIONS:
572                 ret = ptrace_setoptions(child, data);
573                 break;
574         case PTRACE_GETEVENTMSG:
575                 ret = put_user(child->ptrace_message, (unsigned long __user *) data);
576                 break;
577
578         case PTRACE_GETSIGINFO:
579                 ret = ptrace_getsiginfo(child, &siginfo);
580                 if (!ret)
581                         ret = copy_siginfo_to_user((siginfo_t __user *) data,
582                                                    &siginfo);
583                 break;
584
585         case PTRACE_SETSIGINFO:
586                 if (copy_from_user(&siginfo, (siginfo_t __user *) data,
587                                    sizeof siginfo))
588                         ret = -EFAULT;
589                 else
590                         ret = ptrace_setsiginfo(child, &siginfo);
591                 break;
592
593         case PTRACE_DETACH:      /* detach a process that was attached. */
594                 ret = ptrace_detach(child, data);
595                 break;
596
597 #ifdef CONFIG_BINFMT_ELF_FDPIC
598         case PTRACE_GETFDPIC: {
599                 struct mm_struct *mm = get_task_mm(child);
600                 unsigned long tmp = 0;
601
602                 ret = -ESRCH;
603                 if (!mm)
604                         break;
605
606                 switch (addr) {
607                 case PTRACE_GETFDPIC_EXEC:
608                         tmp = mm->context.exec_fdpic_loadmap;
609                         break;
610                 case PTRACE_GETFDPIC_INTERP:
611                         tmp = mm->context.interp_fdpic_loadmap;
612                         break;
613                 default:
614                         break;
615                 }
616                 mmput(mm);
617
618                 ret = put_user(tmp, (unsigned long __user *) data);
619                 break;
620         }
621 #endif
622
623 #ifdef PTRACE_SINGLESTEP
624         case PTRACE_SINGLESTEP:
625 #endif
626 #ifdef PTRACE_SINGLEBLOCK
627         case PTRACE_SINGLEBLOCK:
628 #endif
629 #ifdef PTRACE_SYSEMU
630         case PTRACE_SYSEMU:
631         case PTRACE_SYSEMU_SINGLESTEP:
632 #endif
633         case PTRACE_SYSCALL:
634         case PTRACE_CONT:
635                 return ptrace_resume(child, request, data);
636
637         case PTRACE_KILL:
638                 if (child->exit_state)  /* already dead */
639                         return 0;
640                 return ptrace_resume(child, request, SIGKILL);
641
642 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
643         case PTRACE_GETREGSET:
644         case PTRACE_SETREGSET:
645         {
646                 struct iovec kiov;
647                 struct iovec __user *uiov = (struct iovec __user *) data;
648
649                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
650                         return -EFAULT;
651
652                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
653                     __get_user(kiov.iov_len, &uiov->iov_len))
654                         return -EFAULT;
655
656                 ret = ptrace_regset(child, request, addr, &kiov);
657                 if (!ret)
658                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
659                 break;
660         }
661 #endif
662         default:
663                 break;
664         }
665
666         return ret;
667 }
668
669 static struct task_struct *ptrace_get_task_struct(pid_t pid)
670 {
671         struct task_struct *child;
672
673         rcu_read_lock();
674         child = find_task_by_vpid(pid);
675         if (child)
676                 get_task_struct(child);
677         rcu_read_unlock();
678
679         if (!child)
680                 return ERR_PTR(-ESRCH);
681         return child;
682 }
683
684 #ifndef arch_ptrace_attach
685 #define arch_ptrace_attach(child)       do { } while (0)
686 #endif
687
688 SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data)
689 {
690         struct task_struct *child;
691         long ret;
692
693         if (request == PTRACE_TRACEME) {
694                 ret = ptrace_traceme();
695                 if (!ret)
696                         arch_ptrace_attach(current);
697                 goto out;
698         }
699
700         child = ptrace_get_task_struct(pid);
701         if (IS_ERR(child)) {
702                 ret = PTR_ERR(child);
703                 goto out;
704         }
705
706         if (request == PTRACE_ATTACH) {
707                 ret = ptrace_attach(child);
708                 /*
709                  * Some architectures need to do book-keeping after
710                  * a ptrace attach.
711                  */
712                 if (!ret)
713                         arch_ptrace_attach(child);
714                 goto out_put_task_struct;
715         }
716
717         ret = ptrace_check_attach(child, request == PTRACE_KILL);
718         if (ret < 0)
719                 goto out_put_task_struct;
720
721         ret = arch_ptrace(child, request, addr, data);
722
723  out_put_task_struct:
724         put_task_struct(child);
725  out:
726         return ret;
727 }
728
729 int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data)
730 {
731         unsigned long tmp;
732         int copied;
733
734         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
735         if (copied != sizeof(tmp))
736                 return -EIO;
737         return put_user(tmp, (unsigned long __user *)data);
738 }
739
740 int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data)
741 {
742         int copied;
743
744         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
745         return (copied == sizeof(data)) ? 0 : -EIO;
746 }
747
748 #if defined CONFIG_COMPAT
749 #include <linux/compat.h>
750
751 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
752                           compat_ulong_t addr, compat_ulong_t data)
753 {
754         compat_ulong_t __user *datap = compat_ptr(data);
755         compat_ulong_t word;
756         siginfo_t siginfo;
757         int ret;
758
759         switch (request) {
760         case PTRACE_PEEKTEXT:
761         case PTRACE_PEEKDATA:
762                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
763                 if (ret != sizeof(word))
764                         ret = -EIO;
765                 else
766                         ret = put_user(word, datap);
767                 break;
768
769         case PTRACE_POKETEXT:
770         case PTRACE_POKEDATA:
771                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
772                 ret = (ret != sizeof(data) ? -EIO : 0);
773                 break;
774
775         case PTRACE_GETEVENTMSG:
776                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
777                 break;
778
779         case PTRACE_GETSIGINFO:
780                 ret = ptrace_getsiginfo(child, &siginfo);
781                 if (!ret)
782                         ret = copy_siginfo_to_user32(
783                                 (struct compat_siginfo __user *) datap,
784                                 &siginfo);
785                 break;
786
787         case PTRACE_SETSIGINFO:
788                 memset(&siginfo, 0, sizeof siginfo);
789                 if (copy_siginfo_from_user32(
790                             &siginfo, (struct compat_siginfo __user *) datap))
791                         ret = -EFAULT;
792                 else
793                         ret = ptrace_setsiginfo(child, &siginfo);
794                 break;
795 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
796         case PTRACE_GETREGSET:
797         case PTRACE_SETREGSET:
798         {
799                 struct iovec kiov;
800                 struct compat_iovec __user *uiov =
801                         (struct compat_iovec __user *) datap;
802                 compat_uptr_t ptr;
803                 compat_size_t len;
804
805                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
806                         return -EFAULT;
807
808                 if (__get_user(ptr, &uiov->iov_base) ||
809                     __get_user(len, &uiov->iov_len))
810                         return -EFAULT;
811
812                 kiov.iov_base = compat_ptr(ptr);
813                 kiov.iov_len = len;
814
815                 ret = ptrace_regset(child, request, addr, &kiov);
816                 if (!ret)
817                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
818                 break;
819         }
820 #endif
821
822         default:
823                 ret = ptrace_request(child, request, addr, data);
824         }
825
826         return ret;
827 }
828
829 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
830                                   compat_long_t addr, compat_long_t data)
831 {
832         struct task_struct *child;
833         long ret;
834
835         if (request == PTRACE_TRACEME) {
836                 ret = ptrace_traceme();
837                 goto out;
838         }
839
840         child = ptrace_get_task_struct(pid);
841         if (IS_ERR(child)) {
842                 ret = PTR_ERR(child);
843                 goto out;
844         }
845
846         if (request == PTRACE_ATTACH) {
847                 ret = ptrace_attach(child);
848                 /*
849                  * Some architectures need to do book-keeping after
850                  * a ptrace attach.
851                  */
852                 if (!ret)
853                         arch_ptrace_attach(child);
854                 goto out_put_task_struct;
855         }
856
857         ret = ptrace_check_attach(child, request == PTRACE_KILL);
858         if (!ret)
859                 ret = compat_arch_ptrace(child, request, addr, data);
860
861  out_put_task_struct:
862         put_task_struct(child);
863  out:
864         return ret;
865 }
866 #endif  /* CONFIG_COMPAT */