ptrace: remove silly wait_trap variable from ptrace_attach()
[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         int retval;
188
189         audit_ptrace(task);
190
191         retval = -EPERM;
192         if (unlikely(task->flags & PF_KTHREAD))
193                 goto out;
194         if (same_thread_group(task, current))
195                 goto out;
196
197         /*
198          * Protect exec's credential calculations against our interference;
199          * interference; SUID, SGID and LSM creds get determined differently
200          * under ptrace.
201          */
202         retval = -ERESTARTNOINTR;
203         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
204                 goto out;
205
206         task_lock(task);
207         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
208         task_unlock(task);
209         if (retval)
210                 goto unlock_creds;
211
212         write_lock_irq(&tasklist_lock);
213         retval = -EPERM;
214         if (unlikely(task->exit_state))
215                 goto unlock_tasklist;
216         if (task->ptrace)
217                 goto unlock_tasklist;
218
219         task->ptrace = PT_PTRACED;
220         if (task_ns_capable(task, CAP_SYS_PTRACE))
221                 task->ptrace |= PT_PTRACE_CAP;
222
223         __ptrace_link(task, current);
224         send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
225
226         spin_lock(&task->sighand->siglock);
227
228         /*
229          * If the task is already STOPPED, set GROUP_STOP_PENDING and
230          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
231          * will be cleared if the child completes the transition or any
232          * event which clears the group stop states happens.  We'll wait
233          * for the transition to complete before returning from this
234          * function.
235          *
236          * This hides STOPPED -> RUNNING -> TRACED transition from the
237          * attaching thread but a different thread in the same group can
238          * still observe the transient RUNNING state.  IOW, if another
239          * thread's WNOHANG wait(2) on the stopped tracee races against
240          * ATTACH, the wait(2) may fail due to the transient RUNNING.
241          *
242          * The following task_is_stopped() test is safe as both transitions
243          * in and out of STOPPED are protected by siglock.
244          */
245         if (task_is_stopped(task)) {
246                 task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
247                 signal_wake_up(task, 1);
248         }
249
250         spin_unlock(&task->sighand->siglock);
251
252         retval = 0;
253 unlock_tasklist:
254         write_unlock_irq(&tasklist_lock);
255 unlock_creds:
256         mutex_unlock(&task->signal->cred_guard_mutex);
257 out:
258         if (!retval)
259                 wait_event(current->signal->wait_chldexit,
260                            !(task->group_stop & GROUP_STOP_TRAPPING));
261         return retval;
262 }
263
264 /**
265  * ptrace_traceme  --  helper for PTRACE_TRACEME
266  *
267  * Performs checks and sets PT_PTRACED.
268  * Should be used by all ptrace implementations for PTRACE_TRACEME.
269  */
270 static int ptrace_traceme(void)
271 {
272         int ret = -EPERM;
273
274         write_lock_irq(&tasklist_lock);
275         /* Are we already being traced? */
276         if (!current->ptrace) {
277                 ret = security_ptrace_traceme(current->parent);
278                 /*
279                  * Check PF_EXITING to ensure ->real_parent has not passed
280                  * exit_ptrace(). Otherwise we don't report the error but
281                  * pretend ->real_parent untraces us right after return.
282                  */
283                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
284                         current->ptrace = PT_PTRACED;
285                         __ptrace_link(current, current->real_parent);
286                 }
287         }
288         write_unlock_irq(&tasklist_lock);
289
290         return ret;
291 }
292
293 /*
294  * Called with irqs disabled, returns true if childs should reap themselves.
295  */
296 static int ignoring_children(struct sighand_struct *sigh)
297 {
298         int ret;
299         spin_lock(&sigh->siglock);
300         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
301               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
302         spin_unlock(&sigh->siglock);
303         return ret;
304 }
305
306 /*
307  * Called with tasklist_lock held for writing.
308  * Unlink a traced task, and clean it up if it was a traced zombie.
309  * Return true if it needs to be reaped with release_task().
310  * (We can't call release_task() here because we already hold tasklist_lock.)
311  *
312  * If it's a zombie, our attachedness prevented normal parent notification
313  * or self-reaping.  Do notification now if it would have happened earlier.
314  * If it should reap itself, return true.
315  *
316  * If it's our own child, there is no notification to do. But if our normal
317  * children self-reap, then this child was prevented by ptrace and we must
318  * reap it now, in that case we must also wake up sub-threads sleeping in
319  * do_wait().
320  */
321 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
322 {
323         __ptrace_unlink(p);
324
325         if (p->exit_state == EXIT_ZOMBIE) {
326                 if (!task_detached(p) && thread_group_empty(p)) {
327                         if (!same_thread_group(p->real_parent, tracer))
328                                 do_notify_parent(p, p->exit_signal);
329                         else if (ignoring_children(tracer->sighand)) {
330                                 __wake_up_parent(p, tracer);
331                                 p->exit_signal = -1;
332                         }
333                 }
334                 if (task_detached(p)) {
335                         /* Mark it as in the process of being reaped. */
336                         p->exit_state = EXIT_DEAD;
337                         return true;
338                 }
339         }
340
341         return false;
342 }
343
344 static int ptrace_detach(struct task_struct *child, unsigned int data)
345 {
346         bool dead = false;
347
348         if (!valid_signal(data))
349                 return -EIO;
350
351         /* Architecture-specific hardware disable .. */
352         ptrace_disable(child);
353         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
354
355         write_lock_irq(&tasklist_lock);
356         /*
357          * This child can be already killed. Make sure de_thread() or
358          * our sub-thread doing do_wait() didn't do release_task() yet.
359          */
360         if (child->ptrace) {
361                 child->exit_code = data;
362                 dead = __ptrace_detach(current, child);
363         }
364         write_unlock_irq(&tasklist_lock);
365
366         if (unlikely(dead))
367                 release_task(child);
368
369         return 0;
370 }
371
372 /*
373  * Detach all tasks we were using ptrace on. Called with tasklist held
374  * for writing, and returns with it held too. But note it can release
375  * and reacquire the lock.
376  */
377 void exit_ptrace(struct task_struct *tracer)
378         __releases(&tasklist_lock)
379         __acquires(&tasklist_lock)
380 {
381         struct task_struct *p, *n;
382         LIST_HEAD(ptrace_dead);
383
384         if (likely(list_empty(&tracer->ptraced)))
385                 return;
386
387         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
388                 if (__ptrace_detach(tracer, p))
389                         list_add(&p->ptrace_entry, &ptrace_dead);
390         }
391
392         write_unlock_irq(&tasklist_lock);
393         BUG_ON(!list_empty(&tracer->ptraced));
394
395         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
396                 list_del_init(&p->ptrace_entry);
397                 release_task(p);
398         }
399
400         write_lock_irq(&tasklist_lock);
401 }
402
403 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
404 {
405         int copied = 0;
406
407         while (len > 0) {
408                 char buf[128];
409                 int this_len, retval;
410
411                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
412                 retval = access_process_vm(tsk, src, buf, this_len, 0);
413                 if (!retval) {
414                         if (copied)
415                                 break;
416                         return -EIO;
417                 }
418                 if (copy_to_user(dst, buf, retval))
419                         return -EFAULT;
420                 copied += retval;
421                 src += retval;
422                 dst += retval;
423                 len -= retval;
424         }
425         return copied;
426 }
427
428 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
429 {
430         int copied = 0;
431
432         while (len > 0) {
433                 char buf[128];
434                 int this_len, retval;
435
436                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
437                 if (copy_from_user(buf, src, this_len))
438                         return -EFAULT;
439                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
440                 if (!retval) {
441                         if (copied)
442                                 break;
443                         return -EIO;
444                 }
445                 copied += retval;
446                 src += retval;
447                 dst += retval;
448                 len -= retval;
449         }
450         return copied;
451 }
452
453 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
454 {
455         child->ptrace &= ~PT_TRACE_MASK;
456
457         if (data & PTRACE_O_TRACESYSGOOD)
458                 child->ptrace |= PT_TRACESYSGOOD;
459
460         if (data & PTRACE_O_TRACEFORK)
461                 child->ptrace |= PT_TRACE_FORK;
462
463         if (data & PTRACE_O_TRACEVFORK)
464                 child->ptrace |= PT_TRACE_VFORK;
465
466         if (data & PTRACE_O_TRACECLONE)
467                 child->ptrace |= PT_TRACE_CLONE;
468
469         if (data & PTRACE_O_TRACEEXEC)
470                 child->ptrace |= PT_TRACE_EXEC;
471
472         if (data & PTRACE_O_TRACEVFORKDONE)
473                 child->ptrace |= PT_TRACE_VFORK_DONE;
474
475         if (data & PTRACE_O_TRACEEXIT)
476                 child->ptrace |= PT_TRACE_EXIT;
477
478         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
479 }
480
481 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
482 {
483         unsigned long flags;
484         int error = -ESRCH;
485
486         if (lock_task_sighand(child, &flags)) {
487                 error = -EINVAL;
488                 if (likely(child->last_siginfo != NULL)) {
489                         *info = *child->last_siginfo;
490                         error = 0;
491                 }
492                 unlock_task_sighand(child, &flags);
493         }
494         return error;
495 }
496
497 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
498 {
499         unsigned long flags;
500         int error = -ESRCH;
501
502         if (lock_task_sighand(child, &flags)) {
503                 error = -EINVAL;
504                 if (likely(child->last_siginfo != NULL)) {
505                         *child->last_siginfo = *info;
506                         error = 0;
507                 }
508                 unlock_task_sighand(child, &flags);
509         }
510         return error;
511 }
512
513
514 #ifdef PTRACE_SINGLESTEP
515 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
516 #else
517 #define is_singlestep(request)          0
518 #endif
519
520 #ifdef PTRACE_SINGLEBLOCK
521 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
522 #else
523 #define is_singleblock(request)         0
524 #endif
525
526 #ifdef PTRACE_SYSEMU
527 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
528 #else
529 #define is_sysemu_singlestep(request)   0
530 #endif
531
532 static int ptrace_resume(struct task_struct *child, long request,
533                          unsigned long data)
534 {
535         if (!valid_signal(data))
536                 return -EIO;
537
538         if (request == PTRACE_SYSCALL)
539                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
540         else
541                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
542
543 #ifdef TIF_SYSCALL_EMU
544         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
545                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
546         else
547                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
548 #endif
549
550         if (is_singleblock(request)) {
551                 if (unlikely(!arch_has_block_step()))
552                         return -EIO;
553                 user_enable_block_step(child);
554         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
555                 if (unlikely(!arch_has_single_step()))
556                         return -EIO;
557                 user_enable_single_step(child);
558         } else {
559                 user_disable_single_step(child);
560         }
561
562         child->exit_code = data;
563         wake_up_state(child, __TASK_TRACED);
564
565         return 0;
566 }
567
568 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
569
570 static const struct user_regset *
571 find_regset(const struct user_regset_view *view, unsigned int type)
572 {
573         const struct user_regset *regset;
574         int n;
575
576         for (n = 0; n < view->n; ++n) {
577                 regset = view->regsets + n;
578                 if (regset->core_note_type == type)
579                         return regset;
580         }
581
582         return NULL;
583 }
584
585 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
586                          struct iovec *kiov)
587 {
588         const struct user_regset_view *view = task_user_regset_view(task);
589         const struct user_regset *regset = find_regset(view, type);
590         int regset_no;
591
592         if (!regset || (kiov->iov_len % regset->size) != 0)
593                 return -EINVAL;
594
595         regset_no = regset - view->regsets;
596         kiov->iov_len = min(kiov->iov_len,
597                             (__kernel_size_t) (regset->n * regset->size));
598
599         if (req == PTRACE_GETREGSET)
600                 return copy_regset_to_user(task, view, regset_no, 0,
601                                            kiov->iov_len, kiov->iov_base);
602         else
603                 return copy_regset_from_user(task, view, regset_no, 0,
604                                              kiov->iov_len, kiov->iov_base);
605 }
606
607 #endif
608
609 int ptrace_request(struct task_struct *child, long request,
610                    unsigned long addr, unsigned long data)
611 {
612         int ret = -EIO;
613         siginfo_t siginfo;
614         void __user *datavp = (void __user *) data;
615         unsigned long __user *datalp = datavp;
616
617         switch (request) {
618         case PTRACE_PEEKTEXT:
619         case PTRACE_PEEKDATA:
620                 return generic_ptrace_peekdata(child, addr, data);
621         case PTRACE_POKETEXT:
622         case PTRACE_POKEDATA:
623                 return generic_ptrace_pokedata(child, addr, data);
624
625 #ifdef PTRACE_OLDSETOPTIONS
626         case PTRACE_OLDSETOPTIONS:
627 #endif
628         case PTRACE_SETOPTIONS:
629                 ret = ptrace_setoptions(child, data);
630                 break;
631         case PTRACE_GETEVENTMSG:
632                 ret = put_user(child->ptrace_message, datalp);
633                 break;
634
635         case PTRACE_GETSIGINFO:
636                 ret = ptrace_getsiginfo(child, &siginfo);
637                 if (!ret)
638                         ret = copy_siginfo_to_user(datavp, &siginfo);
639                 break;
640
641         case PTRACE_SETSIGINFO:
642                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
643                         ret = -EFAULT;
644                 else
645                         ret = ptrace_setsiginfo(child, &siginfo);
646                 break;
647
648         case PTRACE_DETACH:      /* detach a process that was attached. */
649                 ret = ptrace_detach(child, data);
650                 break;
651
652 #ifdef CONFIG_BINFMT_ELF_FDPIC
653         case PTRACE_GETFDPIC: {
654                 struct mm_struct *mm = get_task_mm(child);
655                 unsigned long tmp = 0;
656
657                 ret = -ESRCH;
658                 if (!mm)
659                         break;
660
661                 switch (addr) {
662                 case PTRACE_GETFDPIC_EXEC:
663                         tmp = mm->context.exec_fdpic_loadmap;
664                         break;
665                 case PTRACE_GETFDPIC_INTERP:
666                         tmp = mm->context.interp_fdpic_loadmap;
667                         break;
668                 default:
669                         break;
670                 }
671                 mmput(mm);
672
673                 ret = put_user(tmp, datalp);
674                 break;
675         }
676 #endif
677
678 #ifdef PTRACE_SINGLESTEP
679         case PTRACE_SINGLESTEP:
680 #endif
681 #ifdef PTRACE_SINGLEBLOCK
682         case PTRACE_SINGLEBLOCK:
683 #endif
684 #ifdef PTRACE_SYSEMU
685         case PTRACE_SYSEMU:
686         case PTRACE_SYSEMU_SINGLESTEP:
687 #endif
688         case PTRACE_SYSCALL:
689         case PTRACE_CONT:
690                 return ptrace_resume(child, request, data);
691
692         case PTRACE_KILL:
693                 if (child->exit_state)  /* already dead */
694                         return 0;
695                 return ptrace_resume(child, request, SIGKILL);
696
697 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
698         case PTRACE_GETREGSET:
699         case PTRACE_SETREGSET:
700         {
701                 struct iovec kiov;
702                 struct iovec __user *uiov = datavp;
703
704                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
705                         return -EFAULT;
706
707                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
708                     __get_user(kiov.iov_len, &uiov->iov_len))
709                         return -EFAULT;
710
711                 ret = ptrace_regset(child, request, addr, &kiov);
712                 if (!ret)
713                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
714                 break;
715         }
716 #endif
717         default:
718                 break;
719         }
720
721         return ret;
722 }
723
724 static struct task_struct *ptrace_get_task_struct(pid_t pid)
725 {
726         struct task_struct *child;
727
728         rcu_read_lock();
729         child = find_task_by_vpid(pid);
730         if (child)
731                 get_task_struct(child);
732         rcu_read_unlock();
733
734         if (!child)
735                 return ERR_PTR(-ESRCH);
736         return child;
737 }
738
739 #ifndef arch_ptrace_attach
740 #define arch_ptrace_attach(child)       do { } while (0)
741 #endif
742
743 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
744                 unsigned long, data)
745 {
746         struct task_struct *child;
747         long ret;
748
749         if (request == PTRACE_TRACEME) {
750                 ret = ptrace_traceme();
751                 if (!ret)
752                         arch_ptrace_attach(current);
753                 goto out;
754         }
755
756         child = ptrace_get_task_struct(pid);
757         if (IS_ERR(child)) {
758                 ret = PTR_ERR(child);
759                 goto out;
760         }
761
762         if (request == PTRACE_ATTACH) {
763                 ret = ptrace_attach(child);
764                 /*
765                  * Some architectures need to do book-keeping after
766                  * a ptrace attach.
767                  */
768                 if (!ret)
769                         arch_ptrace_attach(child);
770                 goto out_put_task_struct;
771         }
772
773         ret = ptrace_check_attach(child, request == PTRACE_KILL);
774         if (ret < 0)
775                 goto out_put_task_struct;
776
777         ret = arch_ptrace(child, request, addr, data);
778
779  out_put_task_struct:
780         put_task_struct(child);
781  out:
782         return ret;
783 }
784
785 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
786                             unsigned long data)
787 {
788         unsigned long tmp;
789         int copied;
790
791         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
792         if (copied != sizeof(tmp))
793                 return -EIO;
794         return put_user(tmp, (unsigned long __user *)data);
795 }
796
797 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
798                             unsigned long data)
799 {
800         int copied;
801
802         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
803         return (copied == sizeof(data)) ? 0 : -EIO;
804 }
805
806 #if defined CONFIG_COMPAT
807 #include <linux/compat.h>
808
809 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
810                           compat_ulong_t addr, compat_ulong_t data)
811 {
812         compat_ulong_t __user *datap = compat_ptr(data);
813         compat_ulong_t word;
814         siginfo_t siginfo;
815         int ret;
816
817         switch (request) {
818         case PTRACE_PEEKTEXT:
819         case PTRACE_PEEKDATA:
820                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
821                 if (ret != sizeof(word))
822                         ret = -EIO;
823                 else
824                         ret = put_user(word, datap);
825                 break;
826
827         case PTRACE_POKETEXT:
828         case PTRACE_POKEDATA:
829                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
830                 ret = (ret != sizeof(data) ? -EIO : 0);
831                 break;
832
833         case PTRACE_GETEVENTMSG:
834                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
835                 break;
836
837         case PTRACE_GETSIGINFO:
838                 ret = ptrace_getsiginfo(child, &siginfo);
839                 if (!ret)
840                         ret = copy_siginfo_to_user32(
841                                 (struct compat_siginfo __user *) datap,
842                                 &siginfo);
843                 break;
844
845         case PTRACE_SETSIGINFO:
846                 memset(&siginfo, 0, sizeof siginfo);
847                 if (copy_siginfo_from_user32(
848                             &siginfo, (struct compat_siginfo __user *) datap))
849                         ret = -EFAULT;
850                 else
851                         ret = ptrace_setsiginfo(child, &siginfo);
852                 break;
853 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
854         case PTRACE_GETREGSET:
855         case PTRACE_SETREGSET:
856         {
857                 struct iovec kiov;
858                 struct compat_iovec __user *uiov =
859                         (struct compat_iovec __user *) datap;
860                 compat_uptr_t ptr;
861                 compat_size_t len;
862
863                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
864                         return -EFAULT;
865
866                 if (__get_user(ptr, &uiov->iov_base) ||
867                     __get_user(len, &uiov->iov_len))
868                         return -EFAULT;
869
870                 kiov.iov_base = compat_ptr(ptr);
871                 kiov.iov_len = len;
872
873                 ret = ptrace_regset(child, request, addr, &kiov);
874                 if (!ret)
875                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
876                 break;
877         }
878 #endif
879
880         default:
881                 ret = ptrace_request(child, request, addr, data);
882         }
883
884         return ret;
885 }
886
887 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
888                                   compat_long_t addr, compat_long_t data)
889 {
890         struct task_struct *child;
891         long ret;
892
893         if (request == PTRACE_TRACEME) {
894                 ret = ptrace_traceme();
895                 goto out;
896         }
897
898         child = ptrace_get_task_struct(pid);
899         if (IS_ERR(child)) {
900                 ret = PTR_ERR(child);
901                 goto out;
902         }
903
904         if (request == PTRACE_ATTACH) {
905                 ret = ptrace_attach(child);
906                 /*
907                  * Some architectures need to do book-keeping after
908                  * a ptrace attach.
909                  */
910                 if (!ret)
911                         arch_ptrace_attach(child);
912                 goto out_put_task_struct;
913         }
914
915         ret = ptrace_check_attach(child, request == PTRACE_KILL);
916         if (!ret)
917                 ret = compat_arch_ptrace(child, request, addr, data);
918
919  out_put_task_struct:
920         put_task_struct(child);
921  out:
922         return ret;
923 }
924 #endif  /* CONFIG_COMPAT */
925
926 #ifdef CONFIG_HAVE_HW_BREAKPOINT
927 int ptrace_get_breakpoints(struct task_struct *tsk)
928 {
929         if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
930                 return 0;
931
932         return -1;
933 }
934
935 void ptrace_put_breakpoints(struct task_struct *tsk)
936 {
937         if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
938                 flush_ptrace_hw_breakpoint(tsk);
939 }
940 #endif /* CONFIG_HAVE_HW_BREAKPOINT */