source: src/linux/universal/linux-3.18/kernel/ptrace.c @ 31885

Last change on this file since 31885 was 31885, checked in by brainslayer, 3 months ago

update

File size: 31.4 KB
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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 */
37void __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}
43
44/**
45 * __ptrace_unlink - unlink ptracee and restore its execution state
46 * @child: ptracee to be unlinked
47 *
48 * Remove @child from the ptrace list, move it back to the original parent,
49 * and restore the execution state so that it conforms to the group stop
50 * state.
51 *
52 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
53 * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
54 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
55 * If the ptracer is exiting, the ptracee can be in any state.
56 *
57 * After detach, the ptracee should be in a state which conforms to the
58 * group stop.  If the group is stopped or in the process of stopping, the
59 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
60 * up from TASK_TRACED.
61 *
62 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
63 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
64 * to but in the opposite direction of what happens while attaching to a
65 * stopped task.  However, in this direction, the intermediate RUNNING
66 * state is not hidden even from the current ptracer and if it immediately
67 * re-attaches and performs a WNOHANG wait(2), it may fail.
68 *
69 * CONTEXT:
70 * write_lock_irq(tasklist_lock)
71 */
72void __ptrace_unlink(struct task_struct *child)
73{
74        BUG_ON(!child->ptrace);
75
76        child->ptrace = 0;
77        child->parent = child->real_parent;
78        list_del_init(&child->ptrace_entry);
79
80        spin_lock(&child->sighand->siglock);
81
82        /*
83         * Clear all pending traps and TRAPPING.  TRAPPING should be
84         * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
85         */
86        task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
87        task_clear_jobctl_trapping(child);
88
89        /*
90         * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
91         * @child isn't dead.
92         */
93        if (!(child->flags & PF_EXITING) &&
94            (child->signal->flags & SIGNAL_STOP_STOPPED ||
95             child->signal->group_stop_count)) {
96                child->jobctl |= JOBCTL_STOP_PENDING;
97
98                /*
99                 * This is only possible if this thread was cloned by the
100                 * traced task running in the stopped group, set the signal
101                 * for the future reports.
102                 * FIXME: we should change ptrace_init_task() to handle this
103                 * case.
104                 */
105                if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
106                        child->jobctl |= SIGSTOP;
107        }
108
109        /*
110         * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
111         * @child in the butt.  Note that @resume should be used iff @child
112         * is in TASK_TRACED; otherwise, we might unduly disrupt
113         * TASK_KILLABLE sleeps.
114         */
115        if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
116                ptrace_signal_wake_up(child, true);
117
118        spin_unlock(&child->sighand->siglock);
119}
120
121/* Ensure that nothing can wake it up, even SIGKILL */
122static bool ptrace_freeze_traced(struct task_struct *task)
123{
124        bool ret = false;
125
126        /* Lockless, nobody but us can set this flag */
127        if (task->jobctl & JOBCTL_LISTENING)
128                return ret;
129
130        spin_lock_irq(&task->sighand->siglock);
131        if (task_is_traced(task) && !__fatal_signal_pending(task)) {
132                task->state = __TASK_TRACED;
133                ret = true;
134        }
135        spin_unlock_irq(&task->sighand->siglock);
136
137        return ret;
138}
139
140static void ptrace_unfreeze_traced(struct task_struct *task)
141{
142        if (task->state != __TASK_TRACED)
143                return;
144
145        WARN_ON(!task->ptrace || task->parent != current);
146
147        /*
148         * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
149         * Recheck state under the lock to close this race.
150         */
151        spin_lock_irq(&task->sighand->siglock);
152        if (task->state == __TASK_TRACED) {
153                if (__fatal_signal_pending(task))
154                        wake_up_state(task, __TASK_TRACED);
155                else
156                        task->state = TASK_TRACED;
157        }
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 */
178static 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
216static 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. */
225static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
226{
227        const struct cred *cred = current_cred(), *tcred;
228        int dumpable = 0;
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;
277ok:
278        rcu_read_unlock();
279        smp_rmb();
280        if (task->mm)
281                dumpable = get_dumpable(task->mm);
282        rcu_read_lock();
283        if (dumpable != SUID_DUMP_USER &&
284            !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {
285                rcu_read_unlock();
286                return -EPERM;
287        }
288        rcu_read_unlock();
289
290        return security_ptrace_access_check(task, mode);
291}
292
293bool ptrace_may_access(struct task_struct *task, unsigned int mode)
294{
295        int err;
296        task_lock(task);
297        err = __ptrace_may_access(task, mode);
298        task_unlock(task);
299        return !err;
300}
301
302static int ptrace_attach(struct task_struct *task, long request,
303                         unsigned long addr,
304                         unsigned long flags)
305{
306        bool seize = (request == PTRACE_SEIZE);
307        int retval;
308
309        retval = -EIO;
310        if (seize) {
311                if (addr != 0)
312                        goto out;
313                if (flags & ~(unsigned long)PTRACE_O_MASK)
314                        goto out;
315                flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
316        } else {
317                flags = PT_PTRACED;
318        }
319
320        audit_ptrace(task);
321
322        retval = -EPERM;
323        if (unlikely(task->flags & PF_KTHREAD))
324                goto out;
325        if (same_thread_group(task, current))
326                goto out;
327
328        /*
329         * Protect exec's credential calculations against our interference;
330         * SUID, SGID and LSM creds get determined differently
331         * under ptrace.
332         */
333        retval = -ERESTARTNOINTR;
334        if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
335                goto out;
336
337        task_lock(task);
338        retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
339        task_unlock(task);
340        if (retval)
341                goto unlock_creds;
342
343        write_lock_irq(&tasklist_lock);
344        retval = -EPERM;
345        if (unlikely(task->exit_state))
346                goto unlock_tasklist;
347        if (task->ptrace)
348                goto unlock_tasklist;
349
350        if (seize)
351                flags |= PT_SEIZED;
352        rcu_read_lock();
353        if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))
354                flags |= PT_PTRACE_CAP;
355        rcu_read_unlock();
356        task->ptrace = flags;
357
358        __ptrace_link(task, current);
359
360        /* SEIZE doesn't trap tracee on attach */
361        if (!seize)
362                send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
363
364        spin_lock(&task->sighand->siglock);
365
366        /*
367         * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
368         * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
369         * will be cleared if the child completes the transition or any
370         * event which clears the group stop states happens.  We'll wait
371         * for the transition to complete before returning from this
372         * function.
373         *
374         * This hides STOPPED -> RUNNING -> TRACED transition from the
375         * attaching thread but a different thread in the same group can
376         * still observe the transient RUNNING state.  IOW, if another
377         * thread's WNOHANG wait(2) on the stopped tracee races against
378         * ATTACH, the wait(2) may fail due to the transient RUNNING.
379         *
380         * The following task_is_stopped() test is safe as both transitions
381         * in and out of STOPPED are protected by siglock.
382         */
383        if (task_is_stopped(task) &&
384            task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
385                signal_wake_up_state(task, __TASK_STOPPED);
386
387        spin_unlock(&task->sighand->siglock);
388
389        retval = 0;
390unlock_tasklist:
391        write_unlock_irq(&tasklist_lock);
392unlock_creds:
393        mutex_unlock(&task->signal->cred_guard_mutex);
394out:
395        if (!retval) {
396                wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
397                            TASK_UNINTERRUPTIBLE);
398                proc_ptrace_connector(task, PTRACE_ATTACH);
399        }
400
401        return retval;
402}
403
404/**
405 * ptrace_traceme  --  helper for PTRACE_TRACEME
406 *
407 * Performs checks and sets PT_PTRACED.
408 * Should be used by all ptrace implementations for PTRACE_TRACEME.
409 */
410static int ptrace_traceme(void)
411{
412        int ret = -EPERM;
413
414        write_lock_irq(&tasklist_lock);
415        /* Are we already being traced? */
416        if (!current->ptrace) {
417                ret = security_ptrace_traceme(current->parent);
418                /*
419                 * Check PF_EXITING to ensure ->real_parent has not passed
420                 * exit_ptrace(). Otherwise we don't report the error but
421                 * pretend ->real_parent untraces us right after return.
422                 */
423                if (!ret && !(current->real_parent->flags & PF_EXITING)) {
424                        current->ptrace = PT_PTRACED;
425                        __ptrace_link(current, current->real_parent);
426                }
427        }
428        write_unlock_irq(&tasklist_lock);
429
430        return ret;
431}
432
433/*
434 * Called with irqs disabled, returns true if childs should reap themselves.
435 */
436static int ignoring_children(struct sighand_struct *sigh)
437{
438        int ret;
439        spin_lock(&sigh->siglock);
440        ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
441              (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
442        spin_unlock(&sigh->siglock);
443        return ret;
444}
445
446/*
447 * Called with tasklist_lock held for writing.
448 * Unlink a traced task, and clean it up if it was a traced zombie.
449 * Return true if it needs to be reaped with release_task().
450 * (We can't call release_task() here because we already hold tasklist_lock.)
451 *
452 * If it's a zombie, our attachedness prevented normal parent notification
453 * or self-reaping.  Do notification now if it would have happened earlier.
454 * If it should reap itself, return true.
455 *
456 * If it's our own child, there is no notification to do. But if our normal
457 * children self-reap, then this child was prevented by ptrace and we must
458 * reap it now, in that case we must also wake up sub-threads sleeping in
459 * do_wait().
460 */
461static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
462{
463        bool dead;
464
465        __ptrace_unlink(p);
466
467        if (p->exit_state != EXIT_ZOMBIE)
468                return false;
469
470        dead = !thread_group_leader(p);
471
472        if (!dead && thread_group_empty(p)) {
473                if (!same_thread_group(p->real_parent, tracer))
474                        dead = do_notify_parent(p, p->exit_signal);
475                else if (ignoring_children(tracer->sighand)) {
476                        __wake_up_parent(p, tracer);
477                        dead = true;
478                }
479        }
480        /* Mark it as in the process of being reaped. */
481        if (dead)
482                p->exit_state = EXIT_DEAD;
483        return dead;
484}
485
486static int ptrace_detach(struct task_struct *child, unsigned int data)
487{
488        bool dead = false;
489
490        if (!valid_signal(data))
491                return -EIO;
492
493        /* Architecture-specific hardware disable .. */
494        ptrace_disable(child);
495        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
496
497        write_lock_irq(&tasklist_lock);
498        /*
499         * This child can be already killed. Make sure de_thread() or
500         * our sub-thread doing do_wait() didn't do release_task() yet.
501         */
502        if (child->ptrace) {
503                child->exit_code = data;
504                dead = __ptrace_detach(current, child);
505        }
506        write_unlock_irq(&tasklist_lock);
507
508        proc_ptrace_connector(child, PTRACE_DETACH);
509        if (unlikely(dead))
510                release_task(child);
511
512        return 0;
513}
514
515/*
516 * Detach all tasks we were using ptrace on. Called with tasklist held
517 * for writing, and returns with it held too. But note it can release
518 * and reacquire the lock.
519 */
520void exit_ptrace(struct task_struct *tracer)
521        __releases(&tasklist_lock)
522        __acquires(&tasklist_lock)
523{
524        struct task_struct *p, *n;
525        LIST_HEAD(ptrace_dead);
526
527        if (likely(list_empty(&tracer->ptraced)))
528                return;
529
530        list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
531                if (unlikely(p->ptrace & PT_EXITKILL))
532                        send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
533
534                if (__ptrace_detach(tracer, p))
535                        list_add(&p->ptrace_entry, &ptrace_dead);
536        }
537
538        write_unlock_irq(&tasklist_lock);
539        BUG_ON(!list_empty(&tracer->ptraced));
540
541        list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
542                list_del_init(&p->ptrace_entry);
543                release_task(p);
544        }
545
546        write_lock_irq(&tasklist_lock);
547}
548
549int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
550{
551        int copied = 0;
552
553        while (len > 0) {
554                char buf[128];
555                int this_len, retval;
556
557                this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
558                retval = access_process_vm(tsk, src, buf, this_len, 0);
559                if (!retval) {
560                        if (copied)
561                                break;
562                        return -EIO;
563                }
564                if (copy_to_user(dst, buf, retval))
565                        return -EFAULT;
566                copied += retval;
567                src += retval;
568                dst += retval;
569                len -= retval;
570        }
571        return copied;
572}
573
574int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
575{
576        int copied = 0;
577
578        while (len > 0) {
579                char buf[128];
580                int this_len, retval;
581
582                this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
583                if (copy_from_user(buf, src, this_len))
584                        return -EFAULT;
585                retval = access_process_vm(tsk, dst, buf, this_len, 1);
586                if (!retval) {
587                        if (copied)
588                                break;
589                        return -EIO;
590                }
591                copied += retval;
592                src += retval;
593                dst += retval;
594                len -= retval;
595        }
596        return copied;
597}
598
599static int ptrace_setoptions(struct task_struct *child, unsigned long data)
600{
601        unsigned flags;
602
603        if (data & ~(unsigned long)PTRACE_O_MASK)
604                return -EINVAL;
605
606        /* Avoid intermediate state when all opts are cleared */
607        flags = child->ptrace;
608        flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
609        flags |= (data << PT_OPT_FLAG_SHIFT);
610        child->ptrace = flags;
611
612        return 0;
613}
614
615static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
616{
617        unsigned long flags;
618        int error = -ESRCH;
619
620        if (lock_task_sighand(child, &flags)) {
621                error = -EINVAL;
622                if (likely(child->last_siginfo != NULL)) {
623                        *info = *child->last_siginfo;
624                        error = 0;
625                }
626                unlock_task_sighand(child, &flags);
627        }
628        return error;
629}
630
631static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
632{
633        unsigned long flags;
634        int error = -ESRCH;
635
636        if (lock_task_sighand(child, &flags)) {
637                error = -EINVAL;
638                if (likely(child->last_siginfo != NULL)) {
639                        *child->last_siginfo = *info;
640                        error = 0;
641                }
642                unlock_task_sighand(child, &flags);
643        }
644        return error;
645}
646
647static int ptrace_peek_siginfo(struct task_struct *child,
648                                unsigned long addr,
649                                unsigned long data)
650{
651        struct ptrace_peeksiginfo_args arg;
652        struct sigpending *pending;
653        struct sigqueue *q;
654        int ret, i;
655
656        ret = copy_from_user(&arg, (void __user *) addr,
657                                sizeof(struct ptrace_peeksiginfo_args));
658        if (ret)
659                return -EFAULT;
660
661        if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
662                return -EINVAL; /* unknown flags */
663
664        if (arg.nr < 0)
665                return -EINVAL;
666
667        if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
668                pending = &child->signal->shared_pending;
669        else
670                pending = &child->pending;
671
672        for (i = 0; i < arg.nr; ) {
673                siginfo_t info;
674                s32 off = arg.off + i;
675
676                spin_lock_irq(&child->sighand->siglock);
677                list_for_each_entry(q, &pending->list, list) {
678                        if (!off--) {
679                                copy_siginfo(&info, &q->info);
680                                break;
681                        }
682                }
683                spin_unlock_irq(&child->sighand->siglock);
684
685                if (off >= 0) /* beyond the end of the list */
686                        break;
687
688#ifdef CONFIG_COMPAT
689                if (unlikely(is_compat_task())) {
690                        compat_siginfo_t __user *uinfo = compat_ptr(data);
691
692                        if (copy_siginfo_to_user32(uinfo, &info) ||
693                            __put_user(info.si_code, &uinfo->si_code)) {
694                                ret = -EFAULT;
695                                break;
696                        }
697
698                } else
699#endif
700                {
701                        siginfo_t __user *uinfo = (siginfo_t __user *) data;
702
703                        if (copy_siginfo_to_user(uinfo, &info) ||
704                            __put_user(info.si_code, &uinfo->si_code)) {
705                                ret = -EFAULT;
706                                break;
707                        }
708                }
709
710                data += sizeof(siginfo_t);
711                i++;
712
713                if (signal_pending(current))
714                        break;
715
716                cond_resched();
717        }
718
719        if (i > 0)
720                return i;
721
722        return ret;
723}
724
725#ifdef PTRACE_SINGLESTEP
726#define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
727#else
728#define is_singlestep(request)          0
729#endif
730
731#ifdef PTRACE_SINGLEBLOCK
732#define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
733#else
734#define is_singleblock(request)         0
735#endif
736
737#ifdef PTRACE_SYSEMU
738#define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
739#else
740#define is_sysemu_singlestep(request)   0
741#endif
742
743static int ptrace_resume(struct task_struct *child, long request,
744                         unsigned long data)
745{
746        bool need_siglock;
747
748        if (!valid_signal(data))
749                return -EIO;
750
751        if (request == PTRACE_SYSCALL)
752                set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
753        else
754                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
755
756#ifdef TIF_SYSCALL_EMU
757        if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
758                set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
759        else
760                clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
761#endif
762
763        if (is_singleblock(request)) {
764                if (unlikely(!arch_has_block_step()))
765                        return -EIO;
766                user_enable_block_step(child);
767        } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
768                if (unlikely(!arch_has_single_step()))
769                        return -EIO;
770                user_enable_single_step(child);
771        } else {
772                user_disable_single_step(child);
773        }
774
775        /*
776         * Change ->exit_code and ->state under siglock to avoid the race
777         * with wait_task_stopped() in between; a non-zero ->exit_code will
778         * wrongly look like another report from tracee.
779         *
780         * Note that we need siglock even if ->exit_code == data and/or this
781         * status was not reported yet, the new status must not be cleared by
782         * wait_task_stopped() after resume.
783         *
784         * If data == 0 we do not care if wait_task_stopped() reports the old
785         * status and clears the code too; this can't race with the tracee, it
786         * takes siglock after resume.
787         */
788        need_siglock = data && !thread_group_empty(current);
789        if (need_siglock)
790                spin_lock_irq(&child->sighand->siglock);
791        child->exit_code = data;
792        wake_up_state(child, __TASK_TRACED);
793        if (need_siglock)
794                spin_unlock_irq(&child->sighand->siglock);
795
796        return 0;
797}
798
799#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
800
801static const struct user_regset *
802find_regset(const struct user_regset_view *view, unsigned int type)
803{
804        const struct user_regset *regset;
805        int n;
806
807        for (n = 0; n < view->n; ++n) {
808                regset = view->regsets + n;
809                if (regset->core_note_type == type)
810                        return regset;
811        }
812
813        return NULL;
814}
815
816static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
817                         struct iovec *kiov)
818{
819        const struct user_regset_view *view = task_user_regset_view(task);
820        const struct user_regset *regset = find_regset(view, type);
821        int regset_no;
822
823        if (!regset || (kiov->iov_len % regset->size) != 0)
824                return -EINVAL;
825
826        regset_no = regset - view->regsets;
827        kiov->iov_len = min(kiov->iov_len,
828                            (__kernel_size_t) (regset->n * regset->size));
829
830        if (req == PTRACE_GETREGSET)
831                return copy_regset_to_user(task, view, regset_no, 0,
832                                           kiov->iov_len, kiov->iov_base);
833        else
834                return copy_regset_from_user(task, view, regset_no, 0,
835                                             kiov->iov_len, kiov->iov_base);
836}
837
838/*
839 * This is declared in linux/regset.h and defined in machine-dependent
840 * code.  We put the export here, near the primary machine-neutral use,
841 * to ensure no machine forgets it.
842 */
843EXPORT_SYMBOL_GPL(task_user_regset_view);
844#endif
845
846int ptrace_request(struct task_struct *child, long request,
847                   unsigned long addr, unsigned long data)
848{
849        bool seized = child->ptrace & PT_SEIZED;
850        int ret = -EIO;
851        siginfo_t siginfo, *si;
852        void __user *datavp = (void __user *) data;
853        unsigned long __user *datalp = datavp;
854        unsigned long flags;
855
856        switch (request) {
857        case PTRACE_PEEKTEXT:
858        case PTRACE_PEEKDATA:
859                return generic_ptrace_peekdata(child, addr, data);
860        case PTRACE_POKETEXT:
861        case PTRACE_POKEDATA:
862                return generic_ptrace_pokedata(child, addr, data);
863
864#ifdef PTRACE_OLDSETOPTIONS
865        case PTRACE_OLDSETOPTIONS:
866#endif
867        case PTRACE_SETOPTIONS:
868                ret = ptrace_setoptions(child, data);
869                break;
870        case PTRACE_GETEVENTMSG:
871                ret = put_user(child->ptrace_message, datalp);
872                break;
873
874        case PTRACE_PEEKSIGINFO:
875                ret = ptrace_peek_siginfo(child, addr, data);
876                break;
877
878        case PTRACE_GETSIGINFO:
879                ret = ptrace_getsiginfo(child, &siginfo);
880                if (!ret)
881                        ret = copy_siginfo_to_user(datavp, &siginfo);
882                break;
883
884        case PTRACE_SETSIGINFO:
885                if (copy_from_user(&siginfo, datavp, sizeof siginfo))
886                        ret = -EFAULT;
887                else
888                        ret = ptrace_setsiginfo(child, &siginfo);
889                break;
890
891        case PTRACE_GETSIGMASK:
892                if (addr != sizeof(sigset_t)) {
893                        ret = -EINVAL;
894                        break;
895                }
896
897                if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
898                        ret = -EFAULT;
899                else
900                        ret = 0;
901
902                break;
903
904        case PTRACE_SETSIGMASK: {
905                sigset_t new_set;
906
907                if (addr != sizeof(sigset_t)) {
908                        ret = -EINVAL;
909                        break;
910                }
911
912                if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
913                        ret = -EFAULT;
914                        break;
915                }
916
917                sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
918
919                /*
920                 * Every thread does recalc_sigpending() after resume, so
921                 * retarget_shared_pending() and recalc_sigpending() are not
922                 * called here.
923                 */
924                spin_lock_irq(&child->sighand->siglock);
925                child->blocked = new_set;
926                spin_unlock_irq(&child->sighand->siglock);
927
928                ret = 0;
929                break;
930        }
931
932        case PTRACE_INTERRUPT:
933                /*
934                 * Stop tracee without any side-effect on signal or job
935                 * control.  At least one trap is guaranteed to happen
936                 * after this request.  If @child is already trapped, the
937                 * current trap is not disturbed and another trap will
938                 * happen after the current trap is ended with PTRACE_CONT.
939                 *
940                 * The actual trap might not be PTRACE_EVENT_STOP trap but
941                 * the pending condition is cleared regardless.
942                 */
943                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
944                        break;
945
946                /*
947                 * INTERRUPT doesn't disturb existing trap sans one
948                 * exception.  If ptracer issued LISTEN for the current
949                 * STOP, this INTERRUPT should clear LISTEN and re-trap
950                 * tracee into STOP.
951                 */
952                if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
953                        ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
954
955                unlock_task_sighand(child, &flags);
956                ret = 0;
957                break;
958
959        case PTRACE_LISTEN:
960                /*
961                 * Listen for events.  Tracee must be in STOP.  It's not
962                 * resumed per-se but is not considered to be in TRACED by
963                 * wait(2) or ptrace(2).  If an async event (e.g. group
964                 * stop state change) happens, tracee will enter STOP trap
965                 * again.  Alternatively, ptracer can issue INTERRUPT to
966                 * finish listening and re-trap tracee into STOP.
967                 */
968                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
969                        break;
970
971                si = child->last_siginfo;
972                if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
973                        child->jobctl |= JOBCTL_LISTENING;
974                        /*
975                         * If NOTIFY is set, it means event happened between
976                         * start of this trap and now.  Trigger re-trap.
977                         */
978                        if (child->jobctl & JOBCTL_TRAP_NOTIFY)
979                                ptrace_signal_wake_up(child, true);
980                        ret = 0;
981                }
982                unlock_task_sighand(child, &flags);
983                break;
984
985        case PTRACE_DETACH:      /* detach a process that was attached. */
986                ret = ptrace_detach(child, data);
987                break;
988
989#ifdef CONFIG_BINFMT_ELF_FDPIC
990        case PTRACE_GETFDPIC: {
991                struct mm_struct *mm = get_task_mm(child);
992                unsigned long tmp = 0;
993
994                ret = -ESRCH;
995                if (!mm)
996                        break;
997
998                switch (addr) {
999                case PTRACE_GETFDPIC_EXEC:
1000                        tmp = mm->context.exec_fdpic_loadmap;
1001                        break;
1002                case PTRACE_GETFDPIC_INTERP:
1003                        tmp = mm->context.interp_fdpic_loadmap;
1004                        break;
1005                default:
1006                        break;
1007                }
1008                mmput(mm);
1009
1010                ret = put_user(tmp, datalp);
1011                break;
1012        }
1013#endif
1014
1015#ifdef PTRACE_SINGLESTEP
1016        case PTRACE_SINGLESTEP:
1017#endif
1018#ifdef PTRACE_SINGLEBLOCK
1019        case PTRACE_SINGLEBLOCK:
1020#endif
1021#ifdef PTRACE_SYSEMU
1022        case PTRACE_SYSEMU:
1023        case PTRACE_SYSEMU_SINGLESTEP:
1024#endif
1025        case PTRACE_SYSCALL:
1026        case PTRACE_CONT:
1027                return ptrace_resume(child, request, data);
1028
1029        case PTRACE_KILL:
1030                if (child->exit_state)  /* already dead */
1031                        return 0;
1032                return ptrace_resume(child, request, SIGKILL);
1033
1034#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1035        case PTRACE_GETREGSET:
1036        case PTRACE_SETREGSET: {
1037                struct iovec kiov;
1038                struct iovec __user *uiov = datavp;
1039
1040                if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1041                        return -EFAULT;
1042
1043                if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1044                    __get_user(kiov.iov_len, &uiov->iov_len))
1045                        return -EFAULT;
1046
1047                ret = ptrace_regset(child, request, addr, &kiov);
1048                if (!ret)
1049                        ret = __put_user(kiov.iov_len, &uiov->iov_len);
1050                break;
1051        }
1052#endif
1053        default:
1054                break;
1055        }
1056
1057        return ret;
1058}
1059
1060static struct task_struct *ptrace_get_task_struct(pid_t pid)
1061{
1062        struct task_struct *child;
1063
1064        rcu_read_lock();
1065        child = find_task_by_vpid(pid);
1066        if (child)
1067                get_task_struct(child);
1068        rcu_read_unlock();
1069
1070        if (!child)
1071                return ERR_PTR(-ESRCH);
1072        return child;
1073}
1074
1075#ifndef arch_ptrace_attach
1076#define arch_ptrace_attach(child)       do { } while (0)
1077#endif
1078
1079SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1080                unsigned long, data)
1081{
1082        struct task_struct *child;
1083        long ret;
1084
1085        if (request == PTRACE_TRACEME) {
1086                ret = ptrace_traceme();
1087                if (!ret)
1088                        arch_ptrace_attach(current);
1089                goto out;
1090        }
1091
1092        child = ptrace_get_task_struct(pid);
1093        if (IS_ERR(child)) {
1094                ret = PTR_ERR(child);
1095                goto out;
1096        }
1097
1098        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1099                ret = ptrace_attach(child, request, addr, data);
1100                /*
1101                 * Some architectures need to do book-keeping after
1102                 * a ptrace attach.
1103                 */
1104                if (!ret)
1105                        arch_ptrace_attach(child);
1106                goto out_put_task_struct;
1107        }
1108
1109        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1110                                  request == PTRACE_INTERRUPT);
1111        if (ret < 0)
1112                goto out_put_task_struct;
1113
1114        ret = arch_ptrace(child, request, addr, data);
1115        if (ret || request != PTRACE_DETACH)
1116                ptrace_unfreeze_traced(child);
1117
1118 out_put_task_struct:
1119        put_task_struct(child);
1120 out:
1121        return ret;
1122}
1123
1124int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1125                            unsigned long data)
1126{
1127        unsigned long tmp;
1128        int copied;
1129
1130        copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
1131        if (copied != sizeof(tmp))
1132                return -EIO;
1133        return put_user(tmp, (unsigned long __user *)data);
1134}
1135
1136int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1137                            unsigned long data)
1138{
1139        int copied;
1140
1141        copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
1142        return (copied == sizeof(data)) ? 0 : -EIO;
1143}
1144
1145#if defined CONFIG_COMPAT
1146#include <linux/compat.h>
1147
1148int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1149                          compat_ulong_t addr, compat_ulong_t data)
1150{
1151        compat_ulong_t __user *datap = compat_ptr(data);
1152        compat_ulong_t word;
1153        siginfo_t siginfo;
1154        int ret;
1155
1156        switch (request) {
1157        case PTRACE_PEEKTEXT:
1158        case PTRACE_PEEKDATA:
1159                ret = access_process_vm(child, addr, &word, sizeof(word), 0);
1160                if (ret != sizeof(word))
1161                        ret = -EIO;
1162                else
1163                        ret = put_user(word, datap);
1164                break;
1165
1166        case PTRACE_POKETEXT:
1167        case PTRACE_POKEDATA:
1168                ret = access_process_vm(child, addr, &data, sizeof(data), 1);
1169                ret = (ret != sizeof(data) ? -EIO : 0);
1170                break;
1171
1172        case PTRACE_GETEVENTMSG:
1173                ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1174                break;
1175
1176        case PTRACE_GETSIGINFO:
1177                ret = ptrace_getsiginfo(child, &siginfo);
1178                if (!ret)
1179                        ret = copy_siginfo_to_user32(
1180                                (struct compat_siginfo __user *) datap,
1181                                &siginfo);
1182                break;
1183
1184        case PTRACE_SETSIGINFO:
1185                memset(&siginfo, 0, sizeof siginfo);
1186                if (copy_siginfo_from_user32(
1187                            &siginfo, (struct compat_siginfo __user *) datap))
1188                        ret = -EFAULT;
1189                else
1190                        ret = ptrace_setsiginfo(child, &siginfo);
1191                break;
1192#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1193        case PTRACE_GETREGSET:
1194        case PTRACE_SETREGSET:
1195        {
1196                struct iovec kiov;
1197                struct compat_iovec __user *uiov =
1198                        (struct compat_iovec __user *) datap;
1199                compat_uptr_t ptr;
1200                compat_size_t len;
1201
1202                if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1203                        return -EFAULT;
1204
1205                if (__get_user(ptr, &uiov->iov_base) ||
1206                    __get_user(len, &uiov->iov_len))
1207                        return -EFAULT;
1208
1209                kiov.iov_base = compat_ptr(ptr);
1210                kiov.iov_len = len;
1211
1212                ret = ptrace_regset(child, request, addr, &kiov);
1213                if (!ret)
1214                        ret = __put_user(kiov.iov_len, &uiov->iov_len);
1215                break;
1216        }
1217#endif
1218
1219        default:
1220                ret = ptrace_request(child, request, addr, data);
1221        }
1222
1223        return ret;
1224}
1225
1226COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1227                       compat_long_t, addr, compat_long_t, data)
1228{
1229        struct task_struct *child;
1230        long ret;
1231
1232        if (request == PTRACE_TRACEME) {
1233                ret = ptrace_traceme();
1234                goto out;
1235        }
1236
1237        child = ptrace_get_task_struct(pid);
1238        if (IS_ERR(child)) {
1239                ret = PTR_ERR(child);
1240                goto out;
1241        }
1242
1243        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1244                ret = ptrace_attach(child, request, addr, data);
1245                /*
1246                 * Some architectures need to do book-keeping after
1247                 * a ptrace attach.
1248                 */
1249                if (!ret)
1250                        arch_ptrace_attach(child);
1251                goto out_put_task_struct;
1252        }
1253
1254        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1255                                  request == PTRACE_INTERRUPT);
1256        if (!ret) {
1257                ret = compat_arch_ptrace(child, request, addr, data);
1258                if (ret || request != PTRACE_DETACH)
1259                        ptrace_unfreeze_traced(child);
1260        }
1261
1262 out_put_task_struct:
1263        put_task_struct(child);
1264 out:
1265        return ret;
1266}
1267#endif  /* CONFIG_COMPAT */
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