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