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Linux/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/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  * Access another process' address space via ptrace.
 32  * Source/target buffer must be kernel space,
 33  * Do not walk the page table directly, use get_user_pages
 34  */
 35 int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
 36                      void *buf, int len, unsigned int gup_flags)
 37 {
 38         struct mm_struct *mm;
 39         int ret;
 40 
 41         mm = get_task_mm(tsk);
 42         if (!mm)
 43                 return 0;
 44 
 45         if (!tsk->ptrace ||
 46             (current != tsk->parent) ||
 47             ((get_dumpable(mm) != SUID_DUMP_USER) &&
 48              !ptracer_capable(tsk, mm->user_ns))) {
 49                 mmput(mm);
 50                 return 0;
 51         }
 52 
 53         ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
 54         mmput(mm);
 55 
 56         return ret;
 57 }
 58 
 59 
 60 /*
 61  * ptrace a task: make the debugger its new parent and
 62  * move it to the ptrace list.
 63  *
 64  * Must be called with the tasklist lock write-held.
 65  */
 66 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 67 {
 68         BUG_ON(!list_empty(&child->ptrace_entry));
 69         list_add(&child->ptrace_entry, &new_parent->ptraced);
 70         child->parent = new_parent;
 71         rcu_read_lock();
 72         child->ptracer_cred = get_cred(__task_cred(new_parent));
 73         rcu_read_unlock();
 74 }
 75 
 76 /**
 77  * __ptrace_unlink - unlink ptracee and restore its execution state
 78  * @child: ptracee to be unlinked
 79  *
 80  * Remove @child from the ptrace list, move it back to the original parent,
 81  * and restore the execution state so that it conforms to the group stop
 82  * state.
 83  *
 84  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
 85  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
 86  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
 87  * If the ptracer is exiting, the ptracee can be in any state.
 88  *
 89  * After detach, the ptracee should be in a state which conforms to the
 90  * group stop.  If the group is stopped or in the process of stopping, the
 91  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
 92  * up from TASK_TRACED.
 93  *
 94  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
 95  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
 96  * to but in the opposite direction of what happens while attaching to a
 97  * stopped task.  However, in this direction, the intermediate RUNNING
 98  * state is not hidden even from the current ptracer and if it immediately
 99  * re-attaches and performs a WNOHANG wait(2), it may fail.
100  *
101  * CONTEXT:
102  * write_lock_irq(tasklist_lock)
103  */
104 void __ptrace_unlink(struct task_struct *child)
105 {
106         const struct cred *old_cred;
107         BUG_ON(!child->ptrace);
108 
109         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
110 
111         child->parent = child->real_parent;
112         list_del_init(&child->ptrace_entry);
113         old_cred = child->ptracer_cred;
114         child->ptracer_cred = NULL;
115         put_cred(old_cred);
116 
117         spin_lock(&child->sighand->siglock);
118         child->ptrace = 0;
119         /*
120          * Clear all pending traps and TRAPPING.  TRAPPING should be
121          * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
122          */
123         task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
124         task_clear_jobctl_trapping(child);
125 
126         /*
127          * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
128          * @child isn't dead.
129          */
130         if (!(child->flags & PF_EXITING) &&
131             (child->signal->flags & SIGNAL_STOP_STOPPED ||
132              child->signal->group_stop_count)) {
133                 child->jobctl |= JOBCTL_STOP_PENDING;
134 
135                 /*
136                  * This is only possible if this thread was cloned by the
137                  * traced task running in the stopped group, set the signal
138                  * for the future reports.
139                  * FIXME: we should change ptrace_init_task() to handle this
140                  * case.
141                  */
142                 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
143                         child->jobctl |= SIGSTOP;
144         }
145 
146         /*
147          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
148          * @child in the butt.  Note that @resume should be used iff @child
149          * is in TASK_TRACED; otherwise, we might unduly disrupt
150          * TASK_KILLABLE sleeps.
151          */
152         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
153                 ptrace_signal_wake_up(child, true);
154 
155         spin_unlock(&child->sighand->siglock);
156 }
157 
158 /* Ensure that nothing can wake it up, even SIGKILL */
159 static bool ptrace_freeze_traced(struct task_struct *task)
160 {
161         bool ret = false;
162 
163         /* Lockless, nobody but us can set this flag */
164         if (task->jobctl & JOBCTL_LISTENING)
165                 return ret;
166 
167         spin_lock_irq(&task->sighand->siglock);
168         if (task_is_traced(task) && !__fatal_signal_pending(task)) {
169                 task->state = __TASK_TRACED;
170                 ret = true;
171         }
172         spin_unlock_irq(&task->sighand->siglock);
173 
174         return ret;
175 }
176 
177 static void ptrace_unfreeze_traced(struct task_struct *task)
178 {
179         if (task->state != __TASK_TRACED)
180                 return;
181 
182         WARN_ON(!task->ptrace || task->parent != current);
183 
184         spin_lock_irq(&task->sighand->siglock);
185         if (__fatal_signal_pending(task))
186                 wake_up_state(task, __TASK_TRACED);
187         else
188                 task->state = TASK_TRACED;
189         spin_unlock_irq(&task->sighand->siglock);
190 }
191 
192 /**
193  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
194  * @child: ptracee to check for
195  * @ignore_state: don't check whether @child is currently %TASK_TRACED
196  *
197  * Check whether @child is being ptraced by %current and ready for further
198  * ptrace operations.  If @ignore_state is %false, @child also should be in
199  * %TASK_TRACED state and on return the child is guaranteed to be traced
200  * and not executing.  If @ignore_state is %true, @child can be in any
201  * state.
202  *
203  * CONTEXT:
204  * Grabs and releases tasklist_lock and @child->sighand->siglock.
205  *
206  * RETURNS:
207  * 0 on success, -ESRCH if %child is not ready.
208  */
209 static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
210 {
211         int ret = -ESRCH;
212 
213         /*
214          * We take the read lock around doing both checks to close a
215          * possible race where someone else was tracing our child and
216          * detached between these two checks.  After this locked check,
217          * we are sure that this is our traced child and that can only
218          * be changed by us so it's not changing right after this.
219          */
220         read_lock(&tasklist_lock);
221         if (child->ptrace && child->parent == current) {
222                 WARN_ON(child->state == __TASK_TRACED);
223                 /*
224                  * child->sighand can't be NULL, release_task()
225                  * does ptrace_unlink() before __exit_signal().
226                  */
227                 if (ignore_state || ptrace_freeze_traced(child))
228                         ret = 0;
229         }
230         read_unlock(&tasklist_lock);
231 
232         if (!ret && !ignore_state) {
233                 if (!wait_task_inactive(child, __TASK_TRACED)) {
234                         /*
235                          * This can only happen if may_ptrace_stop() fails and
236                          * ptrace_stop() changes ->state back to TASK_RUNNING,
237                          * so we should not worry about leaking __TASK_TRACED.
238                          */
239                         WARN_ON(child->state == __TASK_TRACED);
240                         ret = -ESRCH;
241                 }
242         }
243 
244         return ret;
245 }
246 
247 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
248 {
249         if (mode & PTRACE_MODE_NOAUDIT)
250                 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
251         else
252                 return has_ns_capability(current, ns, CAP_SYS_PTRACE);
253 }
254 
255 /* Returns 0 on success, -errno on denial. */
256 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
257 {
258         const struct cred *cred = current_cred(), *tcred;
259         struct mm_struct *mm;
260         kuid_t caller_uid;
261         kgid_t caller_gid;
262 
263         if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
264                 WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
265                 return -EPERM;
266         }
267 
268         /* May we inspect the given task?
269          * This check is used both for attaching with ptrace
270          * and for allowing access to sensitive information in /proc.
271          *
272          * ptrace_attach denies several cases that /proc allows
273          * because setting up the necessary parent/child relationship
274          * or halting the specified task is impossible.
275          */
276 
277         /* Don't let security modules deny introspection */
278         if (same_thread_group(task, current))
279                 return 0;
280         rcu_read_lock();
281         if (mode & PTRACE_MODE_FSCREDS) {
282                 caller_uid = cred->fsuid;
283                 caller_gid = cred->fsgid;
284         } else {
285                 /*
286                  * Using the euid would make more sense here, but something
287                  * in userland might rely on the old behavior, and this
288                  * shouldn't be a security problem since
289                  * PTRACE_MODE_REALCREDS implies that the caller explicitly
290                  * used a syscall that requests access to another process
291                  * (and not a filesystem syscall to procfs).
292                  */
293                 caller_uid = cred->uid;
294                 caller_gid = cred->gid;
295         }
296         tcred = __task_cred(task);
297         if (uid_eq(caller_uid, tcred->euid) &&
298             uid_eq(caller_uid, tcred->suid) &&
299             uid_eq(caller_uid, tcred->uid)  &&
300             gid_eq(caller_gid, tcred->egid) &&
301             gid_eq(caller_gid, tcred->sgid) &&
302             gid_eq(caller_gid, tcred->gid))
303                 goto ok;
304         if (ptrace_has_cap(tcred->user_ns, mode))
305                 goto ok;
306         rcu_read_unlock();
307         return -EPERM;
308 ok:
309         rcu_read_unlock();
310         mm = task->mm;
311         if (mm &&
312             ((get_dumpable(mm) != SUID_DUMP_USER) &&
313              !ptrace_has_cap(mm->user_ns, mode)))
314             return -EPERM;
315 
316         return security_ptrace_access_check(task, mode);
317 }
318 
319 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
320 {
321         int err;
322         task_lock(task);
323         err = __ptrace_may_access(task, mode);
324         task_unlock(task);
325         return !err;
326 }
327 
328 static int ptrace_attach(struct task_struct *task, long request,
329                          unsigned long addr,
330                          unsigned long flags)
331 {
332         bool seize = (request == PTRACE_SEIZE);
333         int retval;
334 
335         retval = -EIO;
336         if (seize) {
337                 if (addr != 0)
338                         goto out;
339                 if (flags & ~(unsigned long)PTRACE_O_MASK)
340                         goto out;
341                 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
342         } else {
343                 flags = PT_PTRACED;
344         }
345 
346         audit_ptrace(task);
347 
348         retval = -EPERM;
349         if (unlikely(task->flags & PF_KTHREAD))
350                 goto out;
351         if (same_thread_group(task, current))
352                 goto out;
353 
354         /*
355          * Protect exec's credential calculations against our interference;
356          * SUID, SGID and LSM creds get determined differently
357          * under ptrace.
358          */
359         retval = -ERESTARTNOINTR;
360         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
361                 goto out;
362 
363         task_lock(task);
364         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
365         task_unlock(task);
366         if (retval)
367                 goto unlock_creds;
368 
369         write_lock_irq(&tasklist_lock);
370         retval = -EPERM;
371         if (unlikely(task->exit_state))
372                 goto unlock_tasklist;
373         if (task->ptrace)
374                 goto unlock_tasklist;
375 
376         if (seize)
377                 flags |= PT_SEIZED;
378         task->ptrace = flags;
379 
380         __ptrace_link(task, current);
381 
382         /* SEIZE doesn't trap tracee on attach */
383         if (!seize)
384                 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
385 
386         spin_lock(&task->sighand->siglock);
387 
388         /*
389          * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
390          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
391          * will be cleared if the child completes the transition or any
392          * event which clears the group stop states happens.  We'll wait
393          * for the transition to complete before returning from this
394          * function.
395          *
396          * This hides STOPPED -> RUNNING -> TRACED transition from the
397          * attaching thread but a different thread in the same group can
398          * still observe the transient RUNNING state.  IOW, if another
399          * thread's WNOHANG wait(2) on the stopped tracee races against
400          * ATTACH, the wait(2) may fail due to the transient RUNNING.
401          *
402          * The following task_is_stopped() test is safe as both transitions
403          * in and out of STOPPED are protected by siglock.
404          */
405         if (task_is_stopped(task) &&
406             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
407                 signal_wake_up_state(task, __TASK_STOPPED);
408 
409         spin_unlock(&task->sighand->siglock);
410 
411         retval = 0;
412 unlock_tasklist:
413         write_unlock_irq(&tasklist_lock);
414 unlock_creds:
415         mutex_unlock(&task->signal->cred_guard_mutex);
416 out:
417         if (!retval) {
418                 /*
419                  * We do not bother to change retval or clear JOBCTL_TRAPPING
420                  * if wait_on_bit() was interrupted by SIGKILL. The tracer will
421                  * not return to user-mode, it will exit and clear this bit in
422                  * __ptrace_unlink() if it wasn't already cleared by the tracee;
423                  * and until then nobody can ptrace this task.
424                  */
425                 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE);
426                 proc_ptrace_connector(task, PTRACE_ATTACH);
427         }
428 
429         return retval;
430 }
431 
432 /**
433  * ptrace_traceme  --  helper for PTRACE_TRACEME
434  *
435  * Performs checks and sets PT_PTRACED.
436  * Should be used by all ptrace implementations for PTRACE_TRACEME.
437  */
438 static int ptrace_traceme(void)
439 {
440         int ret = -EPERM;
441 
442         write_lock_irq(&tasklist_lock);
443         /* Are we already being traced? */
444         if (!current->ptrace) {
445                 ret = security_ptrace_traceme(current->parent);
446                 /*
447                  * Check PF_EXITING to ensure ->real_parent has not passed
448                  * exit_ptrace(). Otherwise we don't report the error but
449                  * pretend ->real_parent untraces us right after return.
450                  */
451                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
452                         current->ptrace = PT_PTRACED;
453                         __ptrace_link(current, current->real_parent);
454                 }
455         }
456         write_unlock_irq(&tasklist_lock);
457 
458         return ret;
459 }
460 
461 /*
462  * Called with irqs disabled, returns true if childs should reap themselves.
463  */
464 static int ignoring_children(struct sighand_struct *sigh)
465 {
466         int ret;
467         spin_lock(&sigh->siglock);
468         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
469               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
470         spin_unlock(&sigh->siglock);
471         return ret;
472 }
473 
474 /*
475  * Called with tasklist_lock held for writing.
476  * Unlink a traced task, and clean it up if it was a traced zombie.
477  * Return true if it needs to be reaped with release_task().
478  * (We can't call release_task() here because we already hold tasklist_lock.)
479  *
480  * If it's a zombie, our attachedness prevented normal parent notification
481  * or self-reaping.  Do notification now if it would have happened earlier.
482  * If it should reap itself, return true.
483  *
484  * If it's our own child, there is no notification to do. But if our normal
485  * children self-reap, then this child was prevented by ptrace and we must
486  * reap it now, in that case we must also wake up sub-threads sleeping in
487  * do_wait().
488  */
489 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
490 {
491         bool dead;
492 
493         __ptrace_unlink(p);
494 
495         if (p->exit_state != EXIT_ZOMBIE)
496                 return false;
497 
498         dead = !thread_group_leader(p);
499 
500         if (!dead && thread_group_empty(p)) {
501                 if (!same_thread_group(p->real_parent, tracer))
502                         dead = do_notify_parent(p, p->exit_signal);
503                 else if (ignoring_children(tracer->sighand)) {
504                         __wake_up_parent(p, tracer);
505                         dead = true;
506                 }
507         }
508         /* Mark it as in the process of being reaped. */
509         if (dead)
510                 p->exit_state = EXIT_DEAD;
511         return dead;
512 }
513 
514 static int ptrace_detach(struct task_struct *child, unsigned int data)
515 {
516         if (!valid_signal(data))
517                 return -EIO;
518 
519         /* Architecture-specific hardware disable .. */
520         ptrace_disable(child);
521 
522         write_lock_irq(&tasklist_lock);
523         /*
524          * We rely on ptrace_freeze_traced(). It can't be killed and
525          * untraced by another thread, it can't be a zombie.
526          */
527         WARN_ON(!child->ptrace || child->exit_state);
528         /*
529          * tasklist_lock avoids the race with wait_task_stopped(), see
530          * the comment in ptrace_resume().
531          */
532         child->exit_code = data;
533         __ptrace_detach(current, child);
534         write_unlock_irq(&tasklist_lock);
535 
536         proc_ptrace_connector(child, PTRACE_DETACH);
537 
538         return 0;
539 }
540 
541 /*
542  * Detach all tasks we were using ptrace on. Called with tasklist held
543  * for writing.
544  */
545 void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
546 {
547         struct task_struct *p, *n;
548 
549         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
550                 if (unlikely(p->ptrace & PT_EXITKILL))
551                         send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
552 
553                 if (__ptrace_detach(tracer, p))
554                         list_add(&p->ptrace_entry, dead);
555         }
556 }
557 
558 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
559 {
560         int copied = 0;
561 
562         while (len > 0) {
563                 char buf[128];
564                 int this_len, retval;
565 
566                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
567                 retval = ptrace_access_vm(tsk, src, buf, this_len, FOLL_FORCE);
568 
569                 if (!retval) {
570                         if (copied)
571                                 break;
572                         return -EIO;
573                 }
574                 if (copy_to_user(dst, buf, retval))
575                         return -EFAULT;
576                 copied += retval;
577                 src += retval;
578                 dst += retval;
579                 len -= retval;
580         }
581         return copied;
582 }
583 
584 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
585 {
586         int copied = 0;
587 
588         while (len > 0) {
589                 char buf[128];
590                 int this_len, retval;
591 
592                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
593                 if (copy_from_user(buf, src, this_len))
594                         return -EFAULT;
595                 retval = ptrace_access_vm(tsk, dst, buf, this_len,
596                                 FOLL_FORCE | FOLL_WRITE);
597                 if (!retval) {
598                         if (copied)
599                                 break;
600                         return -EIO;
601                 }
602                 copied += retval;
603                 src += retval;
604                 dst += retval;
605                 len -= retval;
606         }
607         return copied;
608 }
609 
610 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
611 {
612         unsigned flags;
613 
614         if (data & ~(unsigned long)PTRACE_O_MASK)
615                 return -EINVAL;
616 
617         if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
618                 if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
619                     !IS_ENABLED(CONFIG_SECCOMP))
620                         return -EINVAL;
621 
622                 if (!capable(CAP_SYS_ADMIN))
623                         return -EPERM;
624 
625                 if (seccomp_mode(&current->seccomp) != SECCOMP_MODE_DISABLED ||
626                     current->ptrace & PT_SUSPEND_SECCOMP)
627                         return -EPERM;
628         }
629 
630         /* Avoid intermediate state when all opts are cleared */
631         flags = child->ptrace;
632         flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
633         flags |= (data << PT_OPT_FLAG_SHIFT);
634         child->ptrace = flags;
635 
636         return 0;
637 }
638 
639 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
640 {
641         unsigned long flags;
642         int error = -ESRCH;
643 
644         if (lock_task_sighand(child, &flags)) {
645                 error = -EINVAL;
646                 if (likely(child->last_siginfo != NULL)) {
647                         *info = *child->last_siginfo;
648                         error = 0;
649                 }
650                 unlock_task_sighand(child, &flags);
651         }
652         return error;
653 }
654 
655 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
656 {
657         unsigned long flags;
658         int error = -ESRCH;
659 
660         if (lock_task_sighand(child, &flags)) {
661                 error = -EINVAL;
662                 if (likely(child->last_siginfo != NULL)) {
663                         *child->last_siginfo = *info;
664                         error = 0;
665                 }
666                 unlock_task_sighand(child, &flags);
667         }
668         return error;
669 }
670 
671 static int ptrace_peek_siginfo(struct task_struct *child,
672                                 unsigned long addr,
673                                 unsigned long data)
674 {
675         struct ptrace_peeksiginfo_args arg;
676         struct sigpending *pending;
677         struct sigqueue *q;
678         int ret, i;
679 
680         ret = copy_from_user(&arg, (void __user *) addr,
681                                 sizeof(struct ptrace_peeksiginfo_args));
682         if (ret)
683                 return -EFAULT;
684 
685         if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
686                 return -EINVAL; /* unknown flags */
687 
688         if (arg.nr < 0)
689                 return -EINVAL;
690 
691         if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
692                 pending = &child->signal->shared_pending;
693         else
694                 pending = &child->pending;
695 
696         for (i = 0; i < arg.nr; ) {
697                 siginfo_t info;
698                 s32 off = arg.off + i;
699 
700                 spin_lock_irq(&child->sighand->siglock);
701                 list_for_each_entry(q, &pending->list, list) {
702                         if (!off--) {
703                                 copy_siginfo(&info, &q->info);
704                                 break;
705                         }
706                 }
707                 spin_unlock_irq(&child->sighand->siglock);
708 
709                 if (off >= 0) /* beyond the end of the list */
710                         break;
711 
712 #ifdef CONFIG_COMPAT
713                 if (unlikely(in_compat_syscall())) {
714                         compat_siginfo_t __user *uinfo = compat_ptr(data);
715 
716                         if (copy_siginfo_to_user32(uinfo, &info) ||
717                             __put_user(info.si_code, &uinfo->si_code)) {
718                                 ret = -EFAULT;
719                                 break;
720                         }
721 
722                 } else
723 #endif
724                 {
725                         siginfo_t __user *uinfo = (siginfo_t __user *) data;
726 
727                         if (copy_siginfo_to_user(uinfo, &info) ||
728                             __put_user(info.si_code, &uinfo->si_code)) {
729                                 ret = -EFAULT;
730                                 break;
731                         }
732                 }
733 
734                 data += sizeof(siginfo_t);
735                 i++;
736 
737                 if (signal_pending(current))
738                         break;
739 
740                 cond_resched();
741         }
742 
743         if (i > 0)
744                 return i;
745 
746         return ret;
747 }
748 
749 #ifdef PTRACE_SINGLESTEP
750 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
751 #else
752 #define is_singlestep(request)          0
753 #endif
754 
755 #ifdef PTRACE_SINGLEBLOCK
756 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
757 #else
758 #define is_singleblock(request)         0
759 #endif
760 
761 #ifdef PTRACE_SYSEMU
762 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
763 #else
764 #define is_sysemu_singlestep(request)   0
765 #endif
766 
767 static int ptrace_resume(struct task_struct *child, long request,
768                          unsigned long data)
769 {
770         bool need_siglock;
771 
772         if (!valid_signal(data))
773                 return -EIO;
774 
775         if (request == PTRACE_SYSCALL)
776                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
777         else
778                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
779 
780 #ifdef TIF_SYSCALL_EMU
781         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
782                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
783         else
784                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
785 #endif
786 
787         if (is_singleblock(request)) {
788                 if (unlikely(!arch_has_block_step()))
789                         return -EIO;
790                 user_enable_block_step(child);
791         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
792                 if (unlikely(!arch_has_single_step()))
793                         return -EIO;
794                 user_enable_single_step(child);
795         } else {
796                 user_disable_single_step(child);
797         }
798 
799         /*
800          * Change ->exit_code and ->state under siglock to avoid the race
801          * with wait_task_stopped() in between; a non-zero ->exit_code will
802          * wrongly look like another report from tracee.
803          *
804          * Note that we need siglock even if ->exit_code == data and/or this
805          * status was not reported yet, the new status must not be cleared by
806          * wait_task_stopped() after resume.
807          *
808          * If data == 0 we do not care if wait_task_stopped() reports the old
809          * status and clears the code too; this can't race with the tracee, it
810          * takes siglock after resume.
811          */
812         need_siglock = data && !thread_group_empty(current);
813         if (need_siglock)
814                 spin_lock_irq(&child->sighand->siglock);
815         child->exit_code = data;
816         wake_up_state(child, __TASK_TRACED);
817         if (need_siglock)
818                 spin_unlock_irq(&child->sighand->siglock);
819 
820         return 0;
821 }
822 
823 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
824 
825 static const struct user_regset *
826 find_regset(const struct user_regset_view *view, unsigned int type)
827 {
828         const struct user_regset *regset;
829         int n;
830 
831         for (n = 0; n < view->n; ++n) {
832                 regset = view->regsets + n;
833                 if (regset->core_note_type == type)
834                         return regset;
835         }
836 
837         return NULL;
838 }
839 
840 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
841                          struct iovec *kiov)
842 {
843         const struct user_regset_view *view = task_user_regset_view(task);
844         const struct user_regset *regset = find_regset(view, type);
845         int regset_no;
846 
847         if (!regset || (kiov->iov_len % regset->size) != 0)
848                 return -EINVAL;
849 
850         regset_no = regset - view->regsets;
851         kiov->iov_len = min(kiov->iov_len,
852                             (__kernel_size_t) (regset->n * regset->size));
853 
854         if (req == PTRACE_GETREGSET)
855                 return copy_regset_to_user(task, view, regset_no, 0,
856                                            kiov->iov_len, kiov->iov_base);
857         else
858                 return copy_regset_from_user(task, view, regset_no, 0,
859                                              kiov->iov_len, kiov->iov_base);
860 }
861 
862 /*
863  * This is declared in linux/regset.h and defined in machine-dependent
864  * code.  We put the export here, near the primary machine-neutral use,
865  * to ensure no machine forgets it.
866  */
867 EXPORT_SYMBOL_GPL(task_user_regset_view);
868 #endif
869 
870 int ptrace_request(struct task_struct *child, long request,
871                    unsigned long addr, unsigned long data)
872 {
873         bool seized = child->ptrace & PT_SEIZED;
874         int ret = -EIO;
875         siginfo_t siginfo, *si;
876         void __user *datavp = (void __user *) data;
877         unsigned long __user *datalp = datavp;
878         unsigned long flags;
879 
880         switch (request) {
881         case PTRACE_PEEKTEXT:
882         case PTRACE_PEEKDATA:
883                 return generic_ptrace_peekdata(child, addr, data);
884         case PTRACE_POKETEXT:
885         case PTRACE_POKEDATA:
886                 return generic_ptrace_pokedata(child, addr, data);
887 
888 #ifdef PTRACE_OLDSETOPTIONS
889         case PTRACE_OLDSETOPTIONS:
890 #endif
891         case PTRACE_SETOPTIONS:
892                 ret = ptrace_setoptions(child, data);
893                 break;
894         case PTRACE_GETEVENTMSG:
895                 ret = put_user(child->ptrace_message, datalp);
896                 break;
897 
898         case PTRACE_PEEKSIGINFO:
899                 ret = ptrace_peek_siginfo(child, addr, data);
900                 break;
901 
902         case PTRACE_GETSIGINFO:
903                 ret = ptrace_getsiginfo(child, &siginfo);
904                 if (!ret)
905                         ret = copy_siginfo_to_user(datavp, &siginfo);
906                 break;
907 
908         case PTRACE_SETSIGINFO:
909                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
910                         ret = -EFAULT;
911                 else
912                         ret = ptrace_setsiginfo(child, &siginfo);
913                 break;
914 
915         case PTRACE_GETSIGMASK:
916                 if (addr != sizeof(sigset_t)) {
917                         ret = -EINVAL;
918                         break;
919                 }
920 
921                 if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
922                         ret = -EFAULT;
923                 else
924                         ret = 0;
925 
926                 break;
927 
928         case PTRACE_SETSIGMASK: {
929                 sigset_t new_set;
930 
931                 if (addr != sizeof(sigset_t)) {
932                         ret = -EINVAL;
933                         break;
934                 }
935 
936                 if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
937                         ret = -EFAULT;
938                         break;
939                 }
940 
941                 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
942 
943                 /*
944                  * Every thread does recalc_sigpending() after resume, so
945                  * retarget_shared_pending() and recalc_sigpending() are not
946                  * called here.
947                  */
948                 spin_lock_irq(&child->sighand->siglock);
949                 child->blocked = new_set;
950                 spin_unlock_irq(&child->sighand->siglock);
951 
952                 ret = 0;
953                 break;
954         }
955 
956         case PTRACE_INTERRUPT:
957                 /*
958                  * Stop tracee without any side-effect on signal or job
959                  * control.  At least one trap is guaranteed to happen
960                  * after this request.  If @child is already trapped, the
961                  * current trap is not disturbed and another trap will
962                  * happen after the current trap is ended with PTRACE_CONT.
963                  *
964                  * The actual trap might not be PTRACE_EVENT_STOP trap but
965                  * the pending condition is cleared regardless.
966                  */
967                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
968                         break;
969 
970                 /*
971                  * INTERRUPT doesn't disturb existing trap sans one
972                  * exception.  If ptracer issued LISTEN for the current
973                  * STOP, this INTERRUPT should clear LISTEN and re-trap
974                  * tracee into STOP.
975                  */
976                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
977                         ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
978 
979                 unlock_task_sighand(child, &flags);
980                 ret = 0;
981                 break;
982 
983         case PTRACE_LISTEN:
984                 /*
985                  * Listen for events.  Tracee must be in STOP.  It's not
986                  * resumed per-se but is not considered to be in TRACED by
987                  * wait(2) or ptrace(2).  If an async event (e.g. group
988                  * stop state change) happens, tracee will enter STOP trap
989                  * again.  Alternatively, ptracer can issue INTERRUPT to
990                  * finish listening and re-trap tracee into STOP.
991                  */
992                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
993                         break;
994 
995                 si = child->last_siginfo;
996                 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
997                         child->jobctl |= JOBCTL_LISTENING;
998                         /*
999                          * If NOTIFY is set, it means event happened between
1000                          * start of this trap and now.  Trigger re-trap.
1001                          */
1002                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
1003                                 ptrace_signal_wake_up(child, true);
1004                         ret = 0;
1005                 }
1006                 unlock_task_sighand(child, &flags);
1007                 break;
1008 
1009         case PTRACE_DETACH:      /* detach a process that was attached. */
1010                 ret = ptrace_detach(child, data);
1011                 break;
1012 
1013 #ifdef CONFIG_BINFMT_ELF_FDPIC
1014         case PTRACE_GETFDPIC: {
1015                 struct mm_struct *mm = get_task_mm(child);
1016                 unsigned long tmp = 0;
1017 
1018                 ret = -ESRCH;
1019                 if (!mm)
1020                         break;
1021 
1022                 switch (addr) {
1023                 case PTRACE_GETFDPIC_EXEC:
1024                         tmp = mm->context.exec_fdpic_loadmap;
1025                         break;
1026                 case PTRACE_GETFDPIC_INTERP:
1027                         tmp = mm->context.interp_fdpic_loadmap;
1028                         break;
1029                 default:
1030                         break;
1031                 }
1032                 mmput(mm);
1033 
1034                 ret = put_user(tmp, datalp);
1035                 break;
1036         }
1037 #endif
1038 
1039 #ifdef PTRACE_SINGLESTEP
1040         case PTRACE_SINGLESTEP:
1041 #endif
1042 #ifdef PTRACE_SINGLEBLOCK
1043         case PTRACE_SINGLEBLOCK:
1044 #endif
1045 #ifdef PTRACE_SYSEMU
1046         case PTRACE_SYSEMU:
1047         case PTRACE_SYSEMU_SINGLESTEP:
1048 #endif
1049         case PTRACE_SYSCALL:
1050         case PTRACE_CONT:
1051                 return ptrace_resume(child, request, data);
1052 
1053         case PTRACE_KILL:
1054                 if (child->exit_state)  /* already dead */
1055                         return 0;
1056                 return ptrace_resume(child, request, SIGKILL);
1057 
1058 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1059         case PTRACE_GETREGSET:
1060         case PTRACE_SETREGSET: {
1061                 struct iovec kiov;
1062                 struct iovec __user *uiov = datavp;
1063 
1064                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1065                         return -EFAULT;
1066 
1067                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1068                     __get_user(kiov.iov_len, &uiov->iov_len))
1069                         return -EFAULT;
1070 
1071                 ret = ptrace_regset(child, request, addr, &kiov);
1072                 if (!ret)
1073                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1074                 break;
1075         }
1076 #endif
1077 
1078         case PTRACE_SECCOMP_GET_FILTER:
1079                 ret = seccomp_get_filter(child, addr, datavp);
1080                 break;
1081 
1082         default:
1083                 break;
1084         }
1085 
1086         return ret;
1087 }
1088 
1089 static struct task_struct *ptrace_get_task_struct(pid_t pid)
1090 {
1091         struct task_struct *child;
1092 
1093         rcu_read_lock();
1094         child = find_task_by_vpid(pid);
1095         if (child)
1096                 get_task_struct(child);
1097         rcu_read_unlock();
1098 
1099         if (!child)
1100                 return ERR_PTR(-ESRCH);
1101         return child;
1102 }
1103 
1104 #ifndef arch_ptrace_attach
1105 #define arch_ptrace_attach(child)       do { } while (0)
1106 #endif
1107 
1108 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1109                 unsigned long, data)
1110 {
1111         struct task_struct *child;
1112         long ret;
1113 
1114         if (request == PTRACE_TRACEME) {
1115                 ret = ptrace_traceme();
1116                 if (!ret)
1117                         arch_ptrace_attach(current);
1118                 goto out;
1119         }
1120 
1121         child = ptrace_get_task_struct(pid);
1122         if (IS_ERR(child)) {
1123                 ret = PTR_ERR(child);
1124                 goto out;
1125         }
1126 
1127         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1128                 ret = ptrace_attach(child, request, addr, data);
1129                 /*
1130                  * Some architectures need to do book-keeping after
1131                  * a ptrace attach.
1132                  */
1133                 if (!ret)
1134                         arch_ptrace_attach(child);
1135                 goto out_put_task_struct;
1136         }
1137 
1138         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1139                                   request == PTRACE_INTERRUPT);
1140         if (ret < 0)
1141                 goto out_put_task_struct;
1142 
1143         ret = arch_ptrace(child, request, addr, data);
1144         if (ret || request != PTRACE_DETACH)
1145                 ptrace_unfreeze_traced(child);
1146 
1147  out_put_task_struct:
1148         put_task_struct(child);
1149  out:
1150         return ret;
1151 }
1152 
1153 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1154                             unsigned long data)
1155 {
1156         unsigned long tmp;
1157         int copied;
1158 
1159         copied = ptrace_access_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE);
1160         if (copied != sizeof(tmp))
1161                 return -EIO;
1162         return put_user(tmp, (unsigned long __user *)data);
1163 }
1164 
1165 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1166                             unsigned long data)
1167 {
1168         int copied;
1169 
1170         copied = ptrace_access_vm(tsk, addr, &data, sizeof(data),
1171                         FOLL_FORCE | FOLL_WRITE);
1172         return (copied == sizeof(data)) ? 0 : -EIO;
1173 }
1174 
1175 #if defined CONFIG_COMPAT
1176 
1177 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1178                           compat_ulong_t addr, compat_ulong_t data)
1179 {
1180         compat_ulong_t __user *datap = compat_ptr(data);
1181         compat_ulong_t word;
1182         siginfo_t siginfo;
1183         int ret;
1184 
1185         switch (request) {
1186         case PTRACE_PEEKTEXT:
1187         case PTRACE_PEEKDATA:
1188                 ret = ptrace_access_vm(child, addr, &word, sizeof(word),
1189                                 FOLL_FORCE);
1190                 if (ret != sizeof(word))
1191                         ret = -EIO;
1192                 else
1193                         ret = put_user(word, datap);
1194                 break;
1195 
1196         case PTRACE_POKETEXT:
1197         case PTRACE_POKEDATA:
1198                 ret = ptrace_access_vm(child, addr, &data, sizeof(data),
1199                                 FOLL_FORCE | FOLL_WRITE);
1200                 ret = (ret != sizeof(data) ? -EIO : 0);
1201                 break;
1202 
1203         case PTRACE_GETEVENTMSG:
1204                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1205                 break;
1206 
1207         case PTRACE_GETSIGINFO:
1208                 ret = ptrace_getsiginfo(child, &siginfo);
1209                 if (!ret)
1210                         ret = copy_siginfo_to_user32(
1211                                 (struct compat_siginfo __user *) datap,
1212                                 &siginfo);
1213                 break;
1214 
1215         case PTRACE_SETSIGINFO:
1216                 memset(&siginfo, 0, sizeof siginfo);
1217                 if (copy_siginfo_from_user32(
1218                             &siginfo, (struct compat_siginfo __user *) datap))
1219                         ret = -EFAULT;
1220                 else
1221                         ret = ptrace_setsiginfo(child, &siginfo);
1222                 break;
1223 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1224         case PTRACE_GETREGSET:
1225         case PTRACE_SETREGSET:
1226         {
1227                 struct iovec kiov;
1228                 struct compat_iovec __user *uiov =
1229                         (struct compat_iovec __user *) datap;
1230                 compat_uptr_t ptr;
1231                 compat_size_t len;
1232 
1233                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1234                         return -EFAULT;
1235 
1236                 if (__get_user(ptr, &uiov->iov_base) ||
1237                     __get_user(len, &uiov->iov_len))
1238                         return -EFAULT;
1239 
1240                 kiov.iov_base = compat_ptr(ptr);
1241                 kiov.iov_len = len;
1242 
1243                 ret = ptrace_regset(child, request, addr, &kiov);
1244                 if (!ret)
1245                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1246                 break;
1247         }
1248 #endif
1249 
1250         default:
1251                 ret = ptrace_request(child, request, addr, data);
1252         }
1253 
1254         return ret;
1255 }
1256 
1257 COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1258                        compat_long_t, addr, compat_long_t, data)
1259 {
1260         struct task_struct *child;
1261         long ret;
1262 
1263         if (request == PTRACE_TRACEME) {
1264                 ret = ptrace_traceme();
1265                 goto out;
1266         }
1267 
1268         child = ptrace_get_task_struct(pid);
1269         if (IS_ERR(child)) {
1270                 ret = PTR_ERR(child);
1271                 goto out;
1272         }
1273 
1274         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1275                 ret = ptrace_attach(child, request, addr, data);
1276                 /*
1277                  * Some architectures need to do book-keeping after
1278                  * a ptrace attach.
1279                  */
1280                 if (!ret)
1281                         arch_ptrace_attach(child);
1282                 goto out_put_task_struct;
1283         }
1284 
1285         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1286                                   request == PTRACE_INTERRUPT);
1287         if (!ret) {
1288                 ret = compat_arch_ptrace(child, request, addr, data);
1289                 if (ret || request != PTRACE_DETACH)
1290                         ptrace_unfreeze_traced(child);
1291         }
1292 
1293  out_put_task_struct:
1294         put_task_struct(child);
1295  out:
1296         return ret;
1297 }
1298 #endif  /* CONFIG_COMPAT */
1299 

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