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TOMOYO Linux Cross Reference
Linux/kernel/ptrace.c

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  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/export.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/uio.h>
 21 #include <linux/audit.h>
 22 #include <linux/pid_namespace.h>
 23 #include <linux/syscalls.h>
 24 #include <linux/uaccess.h>
 25 #include <linux/regset.h>
 26 #include <linux/hw_breakpoint.h>
 27 #include <linux/cn_proc.h>
 28 #include <linux/compat.h>
 29 
 30 
 31 /*
 32  * ptrace a task: make the debugger its new parent and
 33  * move it to the ptrace list.
 34  *
 35  * Must be called with the tasklist lock write-held.
 36  */
 37 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 38 {
 39         BUG_ON(!list_empty(&child->ptrace_entry));
 40         list_add(&child->ptrace_entry, &new_parent->ptraced);
 41         child->parent = new_parent;
 42         rcu_read_lock();
 43         child->ptracer_cred = get_cred(__task_cred(new_parent));
 44         rcu_read_unlock();
 45 }
 46 
 47 /**
 48  * __ptrace_unlink - unlink ptracee and restore its execution state
 49  * @child: ptracee to be unlinked
 50  *
 51  * Remove @child from the ptrace list, move it back to the original parent,
 52  * and restore the execution state so that it conforms to the group stop
 53  * state.
 54  *
 55  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
 56  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
 57  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
 58  * If the ptracer is exiting, the ptracee can be in any state.
 59  *
 60  * After detach, the ptracee should be in a state which conforms to the
 61  * group stop.  If the group is stopped or in the process of stopping, the
 62  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
 63  * up from TASK_TRACED.
 64  *
 65  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
 66  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
 67  * to but in the opposite direction of what happens while attaching to a
 68  * stopped task.  However, in this direction, the intermediate RUNNING
 69  * state is not hidden even from the current ptracer and if it immediately
 70  * re-attaches and performs a WNOHANG wait(2), it may fail.
 71  *
 72  * CONTEXT:
 73  * write_lock_irq(tasklist_lock)
 74  */
 75 void __ptrace_unlink(struct task_struct *child)
 76 {
 77         const struct cred *old_cred;
 78         BUG_ON(!child->ptrace);
 79 
 80         child->parent = child->real_parent;
 81         list_del_init(&child->ptrace_entry);
 82         old_cred = child->ptracer_cred;
 83         child->ptracer_cred = NULL;
 84         put_cred(old_cred);
 85 
 86         spin_lock(&child->sighand->siglock);
 87         child->ptrace = 0;
 88         /*
 89          * Clear all pending traps and TRAPPING.  TRAPPING should be
 90          * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
 91          */
 92         task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
 93         task_clear_jobctl_trapping(child);
 94 
 95         /*
 96          * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
 97          * @child isn't dead.
 98          */
 99         if (!(child->flags & PF_EXITING) &&
100             (child->signal->flags & SIGNAL_STOP_STOPPED ||
101              child->signal->group_stop_count)) {
102                 child->jobctl |= JOBCTL_STOP_PENDING;
103 
104                 /*
105                  * This is only possible if this thread was cloned by the
106                  * traced task running in the stopped group, set the signal
107                  * for the future reports.
108                  * FIXME: we should change ptrace_init_task() to handle this
109                  * case.
110                  */
111                 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
112                         child->jobctl |= SIGSTOP;
113         }
114 
115         /*
116          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
117          * @child in the butt.  Note that @resume should be used iff @child
118          * is in TASK_TRACED; otherwise, we might unduly disrupt
119          * TASK_KILLABLE sleeps.
120          */
121         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
122                 ptrace_signal_wake_up(child, true);
123 
124         spin_unlock(&child->sighand->siglock);
125 }
126 
127 /* Ensure that nothing can wake it up, even SIGKILL */
128 static bool ptrace_freeze_traced(struct task_struct *task)
129 {
130         bool ret = false;
131 
132         /* Lockless, nobody but us can set this flag */
133         if (task->jobctl & JOBCTL_LISTENING)
134                 return ret;
135 
136         spin_lock_irq(&task->sighand->siglock);
137         if (task_is_traced(task) && !__fatal_signal_pending(task)) {
138                 task->state = __TASK_TRACED;
139                 ret = true;
140         }
141         spin_unlock_irq(&task->sighand->siglock);
142 
143         return ret;
144 }
145 
146 static void ptrace_unfreeze_traced(struct task_struct *task)
147 {
148         if (task->state != __TASK_TRACED)
149                 return;
150 
151         WARN_ON(!task->ptrace || task->parent != current);
152 
153         spin_lock_irq(&task->sighand->siglock);
154         if (__fatal_signal_pending(task))
155                 wake_up_state(task, __TASK_TRACED);
156         else
157                 task->state = TASK_TRACED;
158         spin_unlock_irq(&task->sighand->siglock);
159 }
160 
161 /**
162  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
163  * @child: ptracee to check for
164  * @ignore_state: don't check whether @child is currently %TASK_TRACED
165  *
166  * Check whether @child is being ptraced by %current and ready for further
167  * ptrace operations.  If @ignore_state is %false, @child also should be in
168  * %TASK_TRACED state and on return the child is guaranteed to be traced
169  * and not executing.  If @ignore_state is %true, @child can be in any
170  * state.
171  *
172  * CONTEXT:
173  * Grabs and releases tasklist_lock and @child->sighand->siglock.
174  *
175  * RETURNS:
176  * 0 on success, -ESRCH if %child is not ready.
177  */
178 static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
179 {
180         int ret = -ESRCH;
181 
182         /*
183          * We take the read lock around doing both checks to close a
184          * possible race where someone else was tracing our child and
185          * detached between these two checks.  After this locked check,
186          * we are sure that this is our traced child and that can only
187          * be changed by us so it's not changing right after this.
188          */
189         read_lock(&tasklist_lock);
190         if (child->ptrace && child->parent == current) {
191                 WARN_ON(child->state == __TASK_TRACED);
192                 /*
193                  * child->sighand can't be NULL, release_task()
194                  * does ptrace_unlink() before __exit_signal().
195                  */
196                 if (ignore_state || ptrace_freeze_traced(child))
197                         ret = 0;
198         }
199         read_unlock(&tasklist_lock);
200 
201         if (!ret && !ignore_state) {
202                 if (!wait_task_inactive(child, __TASK_TRACED)) {
203                         /*
204                          * This can only happen if may_ptrace_stop() fails and
205                          * ptrace_stop() changes ->state back to TASK_RUNNING,
206                          * so we should not worry about leaking __TASK_TRACED.
207                          */
208                         WARN_ON(child->state == __TASK_TRACED);
209                         ret = -ESRCH;
210                 }
211         }
212 
213         return ret;
214 }
215 
216 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
217 {
218         if (mode & PTRACE_MODE_NOAUDIT)
219                 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
220         else
221                 return has_ns_capability(current, ns, CAP_SYS_PTRACE);
222 }
223 
224 /* Returns 0 on success, -errno on denial. */
225 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
226 {
227         const struct cred *cred = current_cred(), *tcred;
228         struct mm_struct *mm;
229         kuid_t caller_uid;
230         kgid_t caller_gid;
231 
232         if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
233                 WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
234                 return -EPERM;
235         }
236 
237         /* May we inspect the given task?
238          * This check is used both for attaching with ptrace
239          * and for allowing access to sensitive information in /proc.
240          *
241          * ptrace_attach denies several cases that /proc allows
242          * because setting up the necessary parent/child relationship
243          * or halting the specified task is impossible.
244          */
245 
246         /* Don't let security modules deny introspection */
247         if (same_thread_group(task, current))
248                 return 0;
249         rcu_read_lock();
250         if (mode & PTRACE_MODE_FSCREDS) {
251                 caller_uid = cred->fsuid;
252                 caller_gid = cred->fsgid;
253         } else {
254                 /*
255                  * Using the euid would make more sense here, but something
256                  * in userland might rely on the old behavior, and this
257                  * shouldn't be a security problem since
258                  * PTRACE_MODE_REALCREDS implies that the caller explicitly
259                  * used a syscall that requests access to another process
260                  * (and not a filesystem syscall to procfs).
261                  */
262                 caller_uid = cred->uid;
263                 caller_gid = cred->gid;
264         }
265         tcred = __task_cred(task);
266         if (uid_eq(caller_uid, tcred->euid) &&
267             uid_eq(caller_uid, tcred->suid) &&
268             uid_eq(caller_uid, tcred->uid)  &&
269             gid_eq(caller_gid, tcred->egid) &&
270             gid_eq(caller_gid, tcred->sgid) &&
271             gid_eq(caller_gid, tcred->gid))
272                 goto ok;
273         if (ptrace_has_cap(tcred->user_ns, mode))
274                 goto ok;
275         rcu_read_unlock();
276         return -EPERM;
277 ok:
278         rcu_read_unlock();
279         mm = task->mm;
280         if (mm &&
281             ((get_dumpable(mm) != SUID_DUMP_USER) &&
282              !ptrace_has_cap(mm->user_ns, mode)))
283             return -EPERM;
284 
285         return security_ptrace_access_check(task, mode);
286 }
287 
288 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
289 {
290         int err;
291         task_lock(task);
292         err = __ptrace_may_access(task, mode);
293         task_unlock(task);
294         return !err;
295 }
296 
297 static int ptrace_attach(struct task_struct *task, long request,
298                          unsigned long addr,
299                          unsigned long flags)
300 {
301         bool seize = (request == PTRACE_SEIZE);
302         int retval;
303 
304         retval = -EIO;
305         if (seize) {
306                 if (addr != 0)
307                         goto out;
308                 if (flags & ~(unsigned long)PTRACE_O_MASK)
309                         goto out;
310                 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
311         } else {
312                 flags = PT_PTRACED;
313         }
314 
315         audit_ptrace(task);
316 
317         retval = -EPERM;
318         if (unlikely(task->flags & PF_KTHREAD))
319                 goto out;
320         if (same_thread_group(task, current))
321                 goto out;
322 
323         /*
324          * Protect exec's credential calculations against our interference;
325          * SUID, SGID and LSM creds get determined differently
326          * under ptrace.
327          */
328         retval = -ERESTARTNOINTR;
329         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
330                 goto out;
331 
332         task_lock(task);
333         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
334         task_unlock(task);
335         if (retval)
336                 goto unlock_creds;
337 
338         write_lock_irq(&tasklist_lock);
339         retval = -EPERM;
340         if (unlikely(task->exit_state))
341                 goto unlock_tasklist;
342         if (task->ptrace)
343                 goto unlock_tasklist;
344 
345         if (seize)
346                 flags |= PT_SEIZED;
347         task->ptrace = flags;
348 
349         __ptrace_link(task, current);
350 
351         /* SEIZE doesn't trap tracee on attach */
352         if (!seize)
353                 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
354 
355         spin_lock(&task->sighand->siglock);
356 
357         /*
358          * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
359          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
360          * will be cleared if the child completes the transition or any
361          * event which clears the group stop states happens.  We'll wait
362          * for the transition to complete before returning from this
363          * function.
364          *
365          * This hides STOPPED -> RUNNING -> TRACED transition from the
366          * attaching thread but a different thread in the same group can
367          * still observe the transient RUNNING state.  IOW, if another
368          * thread's WNOHANG wait(2) on the stopped tracee races against
369          * ATTACH, the wait(2) may fail due to the transient RUNNING.
370          *
371          * The following task_is_stopped() test is safe as both transitions
372          * in and out of STOPPED are protected by siglock.
373          */
374         if (task_is_stopped(task) &&
375             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
376                 signal_wake_up_state(task, __TASK_STOPPED);
377 
378         spin_unlock(&task->sighand->siglock);
379 
380         retval = 0;
381 unlock_tasklist:
382         write_unlock_irq(&tasklist_lock);
383 unlock_creds:
384         mutex_unlock(&task->signal->cred_guard_mutex);
385 out:
386         if (!retval) {
387                 /*
388                  * We do not bother to change retval or clear JOBCTL_TRAPPING
389                  * if wait_on_bit() was interrupted by SIGKILL. The tracer will
390                  * not return to user-mode, it will exit and clear this bit in
391                  * __ptrace_unlink() if it wasn't already cleared by the tracee;
392                  * and until then nobody can ptrace this task.
393                  */
394                 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE);
395                 proc_ptrace_connector(task, PTRACE_ATTACH);
396         }
397 
398         return retval;
399 }
400 
401 /**
402  * ptrace_traceme  --  helper for PTRACE_TRACEME
403  *
404  * Performs checks and sets PT_PTRACED.
405  * Should be used by all ptrace implementations for PTRACE_TRACEME.
406  */
407 static int ptrace_traceme(void)
408 {
409         int ret = -EPERM;
410 
411         write_lock_irq(&tasklist_lock);
412         /* Are we already being traced? */
413         if (!current->ptrace) {
414                 ret = security_ptrace_traceme(current->parent);
415                 /*
416                  * Check PF_EXITING to ensure ->real_parent has not passed
417                  * exit_ptrace(). Otherwise we don't report the error but
418                  * pretend ->real_parent untraces us right after return.
419                  */
420                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
421                         current->ptrace = PT_PTRACED;
422                         __ptrace_link(current, current->real_parent);
423                 }
424         }
425         write_unlock_irq(&tasklist_lock);
426 
427         return ret;
428 }
429 
430 /*
431  * Called with irqs disabled, returns true if childs should reap themselves.
432  */
433 static int ignoring_children(struct sighand_struct *sigh)
434 {
435         int ret;
436         spin_lock(&sigh->siglock);
437         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
438               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
439         spin_unlock(&sigh->siglock);
440         return ret;
441 }
442 
443 /*
444  * Called with tasklist_lock held for writing.
445  * Unlink a traced task, and clean it up if it was a traced zombie.
446  * Return true if it needs to be reaped with release_task().
447  * (We can't call release_task() here because we already hold tasklist_lock.)
448  *
449  * If it's a zombie, our attachedness prevented normal parent notification
450  * or self-reaping.  Do notification now if it would have happened earlier.
451  * If it should reap itself, return true.
452  *
453  * If it's our own child, there is no notification to do. But if our normal
454  * children self-reap, then this child was prevented by ptrace and we must
455  * reap it now, in that case we must also wake up sub-threads sleeping in
456  * do_wait().
457  */
458 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
459 {
460         bool dead;
461 
462         __ptrace_unlink(p);
463 
464         if (p->exit_state != EXIT_ZOMBIE)
465                 return false;
466 
467         dead = !thread_group_leader(p);
468 
469         if (!dead && thread_group_empty(p)) {
470                 if (!same_thread_group(p->real_parent, tracer))
471                         dead = do_notify_parent(p, p->exit_signal);
472                 else if (ignoring_children(tracer->sighand)) {
473                         __wake_up_parent(p, tracer);
474                         dead = true;
475                 }
476         }
477         /* Mark it as in the process of being reaped. */
478         if (dead)
479                 p->exit_state = EXIT_DEAD;
480         return dead;
481 }
482 
483 static int ptrace_detach(struct task_struct *child, unsigned int data)
484 {
485         if (!valid_signal(data))
486                 return -EIO;
487 
488         /* Architecture-specific hardware disable .. */
489         ptrace_disable(child);
490         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
491 
492         write_lock_irq(&tasklist_lock);
493         /*
494          * We rely on ptrace_freeze_traced(). It can't be killed and
495          * untraced by another thread, it can't be a zombie.
496          */
497         WARN_ON(!child->ptrace || child->exit_state);
498         /*
499          * tasklist_lock avoids the race with wait_task_stopped(), see
500          * the comment in ptrace_resume().
501          */
502         child->exit_code = data;
503         __ptrace_detach(current, child);
504         write_unlock_irq(&tasklist_lock);
505 
506         proc_ptrace_connector(child, PTRACE_DETACH);
507 
508         return 0;
509 }
510 
511 /*
512  * Detach all tasks we were using ptrace on. Called with tasklist held
513  * for writing.
514  */
515 void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
516 {
517         struct task_struct *p, *n;
518 
519         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
520                 if (unlikely(p->ptrace & PT_EXITKILL))
521                         send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
522 
523                 if (__ptrace_detach(tracer, p))
524                         list_add(&p->ptrace_entry, dead);
525         }
526 }
527 
528 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
529 {
530         int copied = 0;
531 
532         while (len > 0) {
533                 char buf[128];
534                 int this_len, retval;
535 
536                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
537                 retval = access_process_vm(tsk, src, buf, this_len, 0);
538                 if (!retval) {
539                         if (copied)
540                                 break;
541                         return -EIO;
542                 }
543                 if (copy_to_user(dst, buf, retval))
544                         return -EFAULT;
545                 copied += retval;
546                 src += retval;
547                 dst += retval;
548                 len -= retval;
549         }
550         return copied;
551 }
552 
553 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
554 {
555         int copied = 0;
556 
557         while (len > 0) {
558                 char buf[128];
559                 int this_len, retval;
560 
561                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
562                 if (copy_from_user(buf, src, this_len))
563                         return -EFAULT;
564                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
565                 if (!retval) {
566                         if (copied)
567                                 break;
568                         return -EIO;
569                 }
570                 copied += retval;
571                 src += retval;
572                 dst += retval;
573                 len -= retval;
574         }
575         return copied;
576 }
577 
578 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
579 {
580         unsigned flags;
581 
582         if (data & ~(unsigned long)PTRACE_O_MASK)
583                 return -EINVAL;
584 
585         if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
586                 if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
587                     !IS_ENABLED(CONFIG_SECCOMP))
588                         return -EINVAL;
589 
590                 if (!capable(CAP_SYS_ADMIN))
591                         return -EPERM;
592 
593                 if (seccomp_mode(&current->seccomp) != SECCOMP_MODE_DISABLED ||
594                     current->ptrace & PT_SUSPEND_SECCOMP)
595                         return -EPERM;
596         }
597 
598         /* Avoid intermediate state when all opts are cleared */
599         flags = child->ptrace;
600         flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
601         flags |= (data << PT_OPT_FLAG_SHIFT);
602         child->ptrace = flags;
603 
604         return 0;
605 }
606 
607 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
608 {
609         unsigned long flags;
610         int error = -ESRCH;
611 
612         if (lock_task_sighand(child, &flags)) {
613                 error = -EINVAL;
614                 if (likely(child->last_siginfo != NULL)) {
615                         *info = *child->last_siginfo;
616                         error = 0;
617                 }
618                 unlock_task_sighand(child, &flags);
619         }
620         return error;
621 }
622 
623 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
624 {
625         unsigned long flags;
626         int error = -ESRCH;
627 
628         if (lock_task_sighand(child, &flags)) {
629                 error = -EINVAL;
630                 if (likely(child->last_siginfo != NULL)) {
631                         *child->last_siginfo = *info;
632                         error = 0;
633                 }
634                 unlock_task_sighand(child, &flags);
635         }
636         return error;
637 }
638 
639 static int ptrace_peek_siginfo(struct task_struct *child,
640                                 unsigned long addr,
641                                 unsigned long data)
642 {
643         struct ptrace_peeksiginfo_args arg;
644         struct sigpending *pending;
645         struct sigqueue *q;
646         int ret, i;
647 
648         ret = copy_from_user(&arg, (void __user *) addr,
649                                 sizeof(struct ptrace_peeksiginfo_args));
650         if (ret)
651                 return -EFAULT;
652 
653         if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
654                 return -EINVAL; /* unknown flags */
655 
656         if (arg.nr < 0)
657                 return -EINVAL;
658 
659         if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
660                 pending = &child->signal->shared_pending;
661         else
662                 pending = &child->pending;
663 
664         for (i = 0; i < arg.nr; ) {
665                 siginfo_t info;
666                 s32 off = arg.off + i;
667 
668                 spin_lock_irq(&child->sighand->siglock);
669                 list_for_each_entry(q, &pending->list, list) {
670                         if (!off--) {
671                                 copy_siginfo(&info, &q->info);
672                                 break;
673                         }
674                 }
675                 spin_unlock_irq(&child->sighand->siglock);
676 
677                 if (off >= 0) /* beyond the end of the list */
678                         break;
679 
680 #ifdef CONFIG_COMPAT
681                 if (unlikely(in_compat_syscall())) {
682                         compat_siginfo_t __user *uinfo = compat_ptr(data);
683 
684                         if (copy_siginfo_to_user32(uinfo, &info) ||
685                             __put_user(info.si_code, &uinfo->si_code)) {
686                                 ret = -EFAULT;
687                                 break;
688                         }
689 
690                 } else
691 #endif
692                 {
693                         siginfo_t __user *uinfo = (siginfo_t __user *) data;
694 
695                         if (copy_siginfo_to_user(uinfo, &info) ||
696                             __put_user(info.si_code, &uinfo->si_code)) {
697                                 ret = -EFAULT;
698                                 break;
699                         }
700                 }
701 
702                 data += sizeof(siginfo_t);
703                 i++;
704 
705                 if (signal_pending(current))
706                         break;
707 
708                 cond_resched();
709         }
710 
711         if (i > 0)
712                 return i;
713 
714         return ret;
715 }
716 
717 #ifdef PTRACE_SINGLESTEP
718 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
719 #else
720 #define is_singlestep(request)          0
721 #endif
722 
723 #ifdef PTRACE_SINGLEBLOCK
724 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
725 #else
726 #define is_singleblock(request)         0
727 #endif
728 
729 #ifdef PTRACE_SYSEMU
730 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
731 #else
732 #define is_sysemu_singlestep(request)   0
733 #endif
734 
735 static int ptrace_resume(struct task_struct *child, long request,
736                          unsigned long data)
737 {
738         bool need_siglock;
739 
740         if (!valid_signal(data))
741                 return -EIO;
742 
743         if (request == PTRACE_SYSCALL)
744                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
745         else
746                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
747 
748 #ifdef TIF_SYSCALL_EMU
749         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
750                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
751         else
752                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
753 #endif
754 
755         if (is_singleblock(request)) {
756                 if (unlikely(!arch_has_block_step()))
757                         return -EIO;
758                 user_enable_block_step(child);
759         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
760                 if (unlikely(!arch_has_single_step()))
761                         return -EIO;
762                 user_enable_single_step(child);
763         } else {
764                 user_disable_single_step(child);
765         }
766 
767         /*
768          * Change ->exit_code and ->state under siglock to avoid the race
769          * with wait_task_stopped() in between; a non-zero ->exit_code will
770          * wrongly look like another report from tracee.
771          *
772          * Note that we need siglock even if ->exit_code == data and/or this
773          * status was not reported yet, the new status must not be cleared by
774          * wait_task_stopped() after resume.
775          *
776          * If data == 0 we do not care if wait_task_stopped() reports the old
777          * status and clears the code too; this can't race with the tracee, it
778          * takes siglock after resume.
779          */
780         need_siglock = data && !thread_group_empty(current);
781         if (need_siglock)
782                 spin_lock_irq(&child->sighand->siglock);
783         child->exit_code = data;
784         wake_up_state(child, __TASK_TRACED);
785         if (need_siglock)
786                 spin_unlock_irq(&child->sighand->siglock);
787 
788         return 0;
789 }
790 
791 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
792 
793 static const struct user_regset *
794 find_regset(const struct user_regset_view *view, unsigned int type)
795 {
796         const struct user_regset *regset;
797         int n;
798 
799         for (n = 0; n < view->n; ++n) {
800                 regset = view->regsets + n;
801                 if (regset->core_note_type == type)
802                         return regset;
803         }
804 
805         return NULL;
806 }
807 
808 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
809                          struct iovec *kiov)
810 {
811         const struct user_regset_view *view = task_user_regset_view(task);
812         const struct user_regset *regset = find_regset(view, type);
813         int regset_no;
814 
815         if (!regset || (kiov->iov_len % regset->size) != 0)
816                 return -EINVAL;
817 
818         regset_no = regset - view->regsets;
819         kiov->iov_len = min(kiov->iov_len,
820                             (__kernel_size_t) (regset->n * regset->size));
821 
822         if (req == PTRACE_GETREGSET)
823                 return copy_regset_to_user(task, view, regset_no, 0,
824                                            kiov->iov_len, kiov->iov_base);
825         else
826                 return copy_regset_from_user(task, view, regset_no, 0,
827                                              kiov->iov_len, kiov->iov_base);
828 }
829 
830 /*
831  * This is declared in linux/regset.h and defined in machine-dependent
832  * code.  We put the export here, near the primary machine-neutral use,
833  * to ensure no machine forgets it.
834  */
835 EXPORT_SYMBOL_GPL(task_user_regset_view);
836 #endif
837 
838 int ptrace_request(struct task_struct *child, long request,
839                    unsigned long addr, unsigned long data)
840 {
841         bool seized = child->ptrace & PT_SEIZED;
842         int ret = -EIO;
843         siginfo_t siginfo, *si;
844         void __user *datavp = (void __user *) data;
845         unsigned long __user *datalp = datavp;
846         unsigned long flags;
847 
848         switch (request) {
849         case PTRACE_PEEKTEXT:
850         case PTRACE_PEEKDATA:
851                 return generic_ptrace_peekdata(child, addr, data);
852         case PTRACE_POKETEXT:
853         case PTRACE_POKEDATA:
854                 return generic_ptrace_pokedata(child, addr, data);
855 
856 #ifdef PTRACE_OLDSETOPTIONS
857         case PTRACE_OLDSETOPTIONS:
858 #endif
859         case PTRACE_SETOPTIONS:
860                 ret = ptrace_setoptions(child, data);
861                 break;
862         case PTRACE_GETEVENTMSG:
863                 ret = put_user(child->ptrace_message, datalp);
864                 break;
865 
866         case PTRACE_PEEKSIGINFO:
867                 ret = ptrace_peek_siginfo(child, addr, data);
868                 break;
869 
870         case PTRACE_GETSIGINFO:
871                 ret = ptrace_getsiginfo(child, &siginfo);
872                 if (!ret)
873                         ret = copy_siginfo_to_user(datavp, &siginfo);
874                 break;
875 
876         case PTRACE_SETSIGINFO:
877                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
878                         ret = -EFAULT;
879                 else
880                         ret = ptrace_setsiginfo(child, &siginfo);
881                 break;
882 
883         case PTRACE_GETSIGMASK:
884                 if (addr != sizeof(sigset_t)) {
885                         ret = -EINVAL;
886                         break;
887                 }
888 
889                 if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
890                         ret = -EFAULT;
891                 else
892                         ret = 0;
893 
894                 break;
895 
896         case PTRACE_SETSIGMASK: {
897                 sigset_t new_set;
898 
899                 if (addr != sizeof(sigset_t)) {
900                         ret = -EINVAL;
901                         break;
902                 }
903 
904                 if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
905                         ret = -EFAULT;
906                         break;
907                 }
908 
909                 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
910 
911                 /*
912                  * Every thread does recalc_sigpending() after resume, so
913                  * retarget_shared_pending() and recalc_sigpending() are not
914                  * called here.
915                  */
916                 spin_lock_irq(&child->sighand->siglock);
917                 child->blocked = new_set;
918                 spin_unlock_irq(&child->sighand->siglock);
919 
920                 ret = 0;
921                 break;
922         }
923 
924         case PTRACE_INTERRUPT:
925                 /*
926                  * Stop tracee without any side-effect on signal or job
927                  * control.  At least one trap is guaranteed to happen
928                  * after this request.  If @child is already trapped, the
929                  * current trap is not disturbed and another trap will
930                  * happen after the current trap is ended with PTRACE_CONT.
931                  *
932                  * The actual trap might not be PTRACE_EVENT_STOP trap but
933                  * the pending condition is cleared regardless.
934                  */
935                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
936                         break;
937 
938                 /*
939                  * INTERRUPT doesn't disturb existing trap sans one
940                  * exception.  If ptracer issued LISTEN for the current
941                  * STOP, this INTERRUPT should clear LISTEN and re-trap
942                  * tracee into STOP.
943                  */
944                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
945                         ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
946 
947                 unlock_task_sighand(child, &flags);
948                 ret = 0;
949                 break;
950 
951         case PTRACE_LISTEN:
952                 /*
953                  * Listen for events.  Tracee must be in STOP.  It's not
954                  * resumed per-se but is not considered to be in TRACED by
955                  * wait(2) or ptrace(2).  If an async event (e.g. group
956                  * stop state change) happens, tracee will enter STOP trap
957                  * again.  Alternatively, ptracer can issue INTERRUPT to
958                  * finish listening and re-trap tracee into STOP.
959                  */
960                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
961                         break;
962 
963                 si = child->last_siginfo;
964                 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
965                         child->jobctl |= JOBCTL_LISTENING;
966                         /*
967                          * If NOTIFY is set, it means event happened between
968                          * start of this trap and now.  Trigger re-trap.
969                          */
970                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
971                                 ptrace_signal_wake_up(child, true);
972                         ret = 0;
973                 }
974                 unlock_task_sighand(child, &flags);
975                 break;
976 
977         case PTRACE_DETACH:      /* detach a process that was attached. */
978                 ret = ptrace_detach(child, data);
979                 break;
980 
981 #ifdef CONFIG_BINFMT_ELF_FDPIC
982         case PTRACE_GETFDPIC: {
983                 struct mm_struct *mm = get_task_mm(child);
984                 unsigned long tmp = 0;
985 
986                 ret = -ESRCH;
987                 if (!mm)
988                         break;
989 
990                 switch (addr) {
991                 case PTRACE_GETFDPIC_EXEC:
992                         tmp = mm->context.exec_fdpic_loadmap;
993                         break;
994                 case PTRACE_GETFDPIC_INTERP:
995                         tmp = mm->context.interp_fdpic_loadmap;
996                         break;
997                 default:
998                         break;
999                 }
1000                 mmput(mm);
1001 
1002                 ret = put_user(tmp, datalp);
1003                 break;
1004         }
1005 #endif
1006 
1007 #ifdef PTRACE_SINGLESTEP
1008         case PTRACE_SINGLESTEP:
1009 #endif
1010 #ifdef PTRACE_SINGLEBLOCK
1011         case PTRACE_SINGLEBLOCK:
1012 #endif
1013 #ifdef PTRACE_SYSEMU
1014         case PTRACE_SYSEMU:
1015         case PTRACE_SYSEMU_SINGLESTEP:
1016 #endif
1017         case PTRACE_SYSCALL:
1018         case PTRACE_CONT:
1019                 return ptrace_resume(child, request, data);
1020 
1021         case PTRACE_KILL:
1022                 if (child->exit_state)  /* already dead */
1023                         return 0;
1024                 return ptrace_resume(child, request, SIGKILL);
1025 
1026 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1027         case PTRACE_GETREGSET:
1028         case PTRACE_SETREGSET: {
1029                 struct iovec kiov;
1030                 struct iovec __user *uiov = datavp;
1031 
1032                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1033                         return -EFAULT;
1034 
1035                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1036                     __get_user(kiov.iov_len, &uiov->iov_len))
1037                         return -EFAULT;
1038 
1039                 ret = ptrace_regset(child, request, addr, &kiov);
1040                 if (!ret)
1041                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1042                 break;
1043         }
1044 #endif
1045 
1046         case PTRACE_SECCOMP_GET_FILTER:
1047                 ret = seccomp_get_filter(child, addr, datavp);
1048                 break;
1049 
1050         default:
1051                 break;
1052         }
1053 
1054         return ret;
1055 }
1056 
1057 static struct task_struct *ptrace_get_task_struct(pid_t pid)
1058 {
1059         struct task_struct *child;
1060 
1061         rcu_read_lock();
1062         child = find_task_by_vpid(pid);
1063         if (child)
1064                 get_task_struct(child);
1065         rcu_read_unlock();
1066 
1067         if (!child)
1068                 return ERR_PTR(-ESRCH);
1069         return child;
1070 }
1071 
1072 #ifndef arch_ptrace_attach
1073 #define arch_ptrace_attach(child)       do { } while (0)
1074 #endif
1075 
1076 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1077                 unsigned long, data)
1078 {
1079         struct task_struct *child;
1080         long ret;
1081         {
1082                 const int rc = ccs_ptrace_permission(request, pid);
1083                 if (rc)
1084                         return rc;
1085         }
1086 
1087         if (request == PTRACE_TRACEME) {
1088                 ret = ptrace_traceme();
1089                 if (!ret)
1090                         arch_ptrace_attach(current);
1091                 goto out;
1092         }
1093 
1094         child = ptrace_get_task_struct(pid);
1095         if (IS_ERR(child)) {
1096                 ret = PTR_ERR(child);
1097                 goto out;
1098         }
1099 
1100         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1101                 ret = ptrace_attach(child, request, addr, data);
1102                 /*
1103                  * Some architectures need to do book-keeping after
1104                  * a ptrace attach.
1105                  */
1106                 if (!ret)
1107                         arch_ptrace_attach(child);
1108                 goto out_put_task_struct;
1109         }
1110 
1111         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1112                                   request == PTRACE_INTERRUPT);
1113         if (ret < 0)
1114                 goto out_put_task_struct;
1115 
1116         ret = arch_ptrace(child, request, addr, data);
1117         if (ret || request != PTRACE_DETACH)
1118                 ptrace_unfreeze_traced(child);
1119 
1120  out_put_task_struct:
1121         put_task_struct(child);
1122  out:
1123         return ret;
1124 }
1125 
1126 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1127                             unsigned long data)
1128 {
1129         unsigned long tmp;
1130         int copied;
1131 
1132         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
1133         if (copied != sizeof(tmp))
1134                 return -EIO;
1135         return put_user(tmp, (unsigned long __user *)data);
1136 }
1137 
1138 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1139                             unsigned long data)
1140 {
1141         int copied;
1142 
1143         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
1144         return (copied == sizeof(data)) ? 0 : -EIO;
1145 }
1146 
1147 #if defined CONFIG_COMPAT
1148 
1149 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1150                           compat_ulong_t addr, compat_ulong_t data)
1151 {
1152         compat_ulong_t __user *datap = compat_ptr(data);
1153         compat_ulong_t word;
1154         siginfo_t siginfo;
1155         int ret;
1156 
1157         switch (request) {
1158         case PTRACE_PEEKTEXT:
1159         case PTRACE_PEEKDATA:
1160                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
1161                 if (ret != sizeof(word))
1162                         ret = -EIO;
1163                 else
1164                         ret = put_user(word, datap);
1165                 break;
1166 
1167         case PTRACE_POKETEXT:
1168         case PTRACE_POKEDATA:
1169                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
1170                 ret = (ret != sizeof(data) ? -EIO : 0);
1171                 break;
1172 
1173         case PTRACE_GETEVENTMSG:
1174                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1175                 break;
1176 
1177         case PTRACE_GETSIGINFO:
1178                 ret = ptrace_getsiginfo(child, &siginfo);
1179                 if (!ret)
1180                         ret = copy_siginfo_to_user32(
1181                                 (struct compat_siginfo __user *) datap,
1182                                 &siginfo);
1183                 break;
1184 
1185         case PTRACE_SETSIGINFO:
1186                 memset(&siginfo, 0, sizeof siginfo);
1187                 if (copy_siginfo_from_user32(
1188                             &siginfo, (struct compat_siginfo __user *) datap))
1189                         ret = -EFAULT;
1190                 else
1191                         ret = ptrace_setsiginfo(child, &siginfo);
1192                 break;
1193 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1194         case PTRACE_GETREGSET:
1195         case PTRACE_SETREGSET:
1196         {
1197                 struct iovec kiov;
1198                 struct compat_iovec __user *uiov =
1199                         (struct compat_iovec __user *) datap;
1200                 compat_uptr_t ptr;
1201                 compat_size_t len;
1202 
1203                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1204                         return -EFAULT;
1205 
1206                 if (__get_user(ptr, &uiov->iov_base) ||
1207                     __get_user(len, &uiov->iov_len))
1208                         return -EFAULT;
1209 
1210                 kiov.iov_base = compat_ptr(ptr);
1211                 kiov.iov_len = len;
1212 
1213                 ret = ptrace_regset(child, request, addr, &kiov);
1214                 if (!ret)
1215                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1216                 break;
1217         }
1218 #endif
1219 
1220         default:
1221                 ret = ptrace_request(child, request, addr, data);
1222         }
1223 
1224         return ret;
1225 }
1226 
1227 COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1228                        compat_long_t, addr, compat_long_t, data)
1229 {
1230         struct task_struct *child;
1231         long ret;
1232         {
1233                 const int rc = ccs_ptrace_permission(request, pid);
1234                 if (rc)
1235                         return rc;
1236         }
1237 
1238         if (request == PTRACE_TRACEME) {
1239                 ret = ptrace_traceme();
1240                 goto out;
1241         }
1242 
1243         child = ptrace_get_task_struct(pid);
1244         if (IS_ERR(child)) {
1245                 ret = PTR_ERR(child);
1246                 goto out;
1247         }
1248 
1249         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1250                 ret = ptrace_attach(child, request, addr, data);
1251                 /*
1252                  * Some architectures need to do book-keeping after
1253                  * a ptrace attach.
1254                  */
1255                 if (!ret)
1256                         arch_ptrace_attach(child);
1257                 goto out_put_task_struct;
1258         }
1259 
1260         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1261                                   request == PTRACE_INTERRUPT);
1262         if (!ret) {
1263                 ret = compat_arch_ptrace(child, request, addr, data);
1264                 if (ret || request != PTRACE_DETACH)
1265                         ptrace_unfreeze_traced(child);
1266         }
1267 
1268  out_put_task_struct:
1269         put_task_struct(child);
1270  out:
1271         return ret;
1272 }
1273 #endif  /* CONFIG_COMPAT */
1274 

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