source: src/linux/universal/linux-4.4/kernel/ptrace.c @ 31859

Last change on this file since 31859 was 31859, checked in by brainslayer, 6 weeks ago

kernel update

File size: 31.4 KB
Line 
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        rcu_read_lock();
43        child->ptracer_cred = get_cred(__task_cred(new_parent));
44        rcu_read_unlock();
45}
46
47/**
48 * __ptrace_unlink - unlink ptracee and restore its execution state
49 * @child: ptracee to be unlinked
50 *
51 * Remove @child from the ptrace list, move it back to the original parent,
52 * and restore the execution state so that it conforms to the group stop
53 * state.
54 *
55 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
56 * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
57 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
58 * If the ptracer is exiting, the ptracee can be in any state.
59 *
60 * After detach, the ptracee should be in a state which conforms to the
61 * group stop.  If the group is stopped or in the process of stopping, the
62 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
63 * up from TASK_TRACED.
64 *
65 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
66 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
67 * to but in the opposite direction of what happens while attaching to a
68 * stopped task.  However, in this direction, the intermediate RUNNING
69 * state is not hidden even from the current ptracer and if it immediately
70 * re-attaches and performs a WNOHANG wait(2), it may fail.
71 *
72 * CONTEXT:
73 * write_lock_irq(tasklist_lock)
74 */
75void __ptrace_unlink(struct task_struct *child)
76{
77        const struct cred *old_cred;
78        BUG_ON(!child->ptrace);
79
80        child->ptrace = 0;
81        child->parent = child->real_parent;
82        list_del_init(&child->ptrace_entry);
83        old_cred = child->ptracer_cred;
84        child->ptracer_cred = NULL;
85        put_cred(old_cred);
86
87        spin_lock(&child->sighand->siglock);
88
89        /*
90         * Clear all pending traps and TRAPPING.  TRAPPING should be
91         * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
92         */
93        task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
94        task_clear_jobctl_trapping(child);
95
96        /*
97         * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
98         * @child isn't dead.
99         */
100        if (!(child->flags & PF_EXITING) &&
101            (child->signal->flags & SIGNAL_STOP_STOPPED ||
102             child->signal->group_stop_count)) {
103                child->jobctl |= JOBCTL_STOP_PENDING;
104
105                /*
106                 * This is only possible if this thread was cloned by the
107                 * traced task running in the stopped group, set the signal
108                 * for the future reports.
109                 * FIXME: we should change ptrace_init_task() to handle this
110                 * case.
111                 */
112                if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
113                        child->jobctl |= SIGSTOP;
114        }
115
116        /*
117         * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
118         * @child in the butt.  Note that @resume should be used iff @child
119         * is in TASK_TRACED; otherwise, we might unduly disrupt
120         * TASK_KILLABLE sleeps.
121         */
122        if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
123                ptrace_signal_wake_up(child, true);
124
125        spin_unlock(&child->sighand->siglock);
126}
127
128/* Ensure that nothing can wake it up, even SIGKILL */
129static bool ptrace_freeze_traced(struct task_struct *task)
130{
131        bool ret = false;
132
133        /* Lockless, nobody but us can set this flag */
134        if (task->jobctl & JOBCTL_LISTENING)
135                return ret;
136
137        spin_lock_irq(&task->sighand->siglock);
138        if (task_is_traced(task) && !__fatal_signal_pending(task)) {
139                task->state = __TASK_TRACED;
140                ret = true;
141        }
142        spin_unlock_irq(&task->sighand->siglock);
143
144        return ret;
145}
146
147static void ptrace_unfreeze_traced(struct task_struct *task)
148{
149        if (task->state != __TASK_TRACED)
150                return;
151
152        WARN_ON(!task->ptrace || task->parent != current);
153
154        /*
155         * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
156         * Recheck state under the lock to close this race.
157         */
158        spin_lock_irq(&task->sighand->siglock);
159        if (task->state == __TASK_TRACED) {
160                if (__fatal_signal_pending(task))
161                        wake_up_state(task, __TASK_TRACED);
162                else
163                        task->state = TASK_TRACED;
164        }
165        spin_unlock_irq(&task->sighand->siglock);
166}
167
168/**
169 * ptrace_check_attach - check whether ptracee is ready for ptrace operation
170 * @child: ptracee to check for
171 * @ignore_state: don't check whether @child is currently %TASK_TRACED
172 *
173 * Check whether @child is being ptraced by %current and ready for further
174 * ptrace operations.  If @ignore_state is %false, @child also should be in
175 * %TASK_TRACED state and on return the child is guaranteed to be traced
176 * and not executing.  If @ignore_state is %true, @child can be in any
177 * state.
178 *
179 * CONTEXT:
180 * Grabs and releases tasklist_lock and @child->sighand->siglock.
181 *
182 * RETURNS:
183 * 0 on success, -ESRCH if %child is not ready.
184 */
185static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
186{
187        int ret = -ESRCH;
188
189        /*
190         * We take the read lock around doing both checks to close a
191         * possible race where someone else was tracing our child and
192         * detached between these two checks.  After this locked check,
193         * we are sure that this is our traced child and that can only
194         * be changed by us so it's not changing right after this.
195         */
196        read_lock(&tasklist_lock);
197        if (child->ptrace && child->parent == current) {
198                WARN_ON(child->state == __TASK_TRACED);
199                /*
200                 * child->sighand can't be NULL, release_task()
201                 * does ptrace_unlink() before __exit_signal().
202                 */
203                if (ignore_state || ptrace_freeze_traced(child))
204                        ret = 0;
205        }
206        read_unlock(&tasklist_lock);
207
208        if (!ret && !ignore_state) {
209                if (!wait_task_inactive(child, __TASK_TRACED)) {
210                        /*
211                         * This can only happen if may_ptrace_stop() fails and
212                         * ptrace_stop() changes ->state back to TASK_RUNNING,
213                         * so we should not worry about leaking __TASK_TRACED.
214                         */
215                        WARN_ON(child->state == __TASK_TRACED);
216                        ret = -ESRCH;
217                }
218        }
219
220        return ret;
221}
222
223static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
224{
225        if (mode & PTRACE_MODE_NOAUDIT)
226                return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
227        else
228                return has_ns_capability(current, ns, CAP_SYS_PTRACE);
229}
230
231/* Returns 0 on success, -errno on denial. */
232static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
233{
234        const struct cred *cred = current_cred(), *tcred;
235        struct mm_struct *mm;
236        kuid_t caller_uid;
237        kgid_t caller_gid;
238
239        if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
240                WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
241                return -EPERM;
242        }
243
244        /* May we inspect the given task?
245         * This check is used both for attaching with ptrace
246         * and for allowing access to sensitive information in /proc.
247         *
248         * ptrace_attach denies several cases that /proc allows
249         * because setting up the necessary parent/child relationship
250         * or halting the specified task is impossible.
251         */
252
253        /* Don't let security modules deny introspection */
254        if (same_thread_group(task, current))
255                return 0;
256        rcu_read_lock();
257        if (mode & PTRACE_MODE_FSCREDS) {
258                caller_uid = cred->fsuid;
259                caller_gid = cred->fsgid;
260        } else {
261                /*
262                 * Using the euid would make more sense here, but something
263                 * in userland might rely on the old behavior, and this
264                 * shouldn't be a security problem since
265                 * PTRACE_MODE_REALCREDS implies that the caller explicitly
266                 * used a syscall that requests access to another process
267                 * (and not a filesystem syscall to procfs).
268                 */
269                caller_uid = cred->uid;
270                caller_gid = cred->gid;
271        }
272        tcred = __task_cred(task);
273        if (uid_eq(caller_uid, tcred->euid) &&
274            uid_eq(caller_uid, tcred->suid) &&
275            uid_eq(caller_uid, tcred->uid)  &&
276            gid_eq(caller_gid, tcred->egid) &&
277            gid_eq(caller_gid, tcred->sgid) &&
278            gid_eq(caller_gid, tcred->gid))
279                goto ok;
280        if (ptrace_has_cap(tcred->user_ns, mode))
281                goto ok;
282        rcu_read_unlock();
283        return -EPERM;
284ok:
285        rcu_read_unlock();
286        mm = task->mm;
287        if (mm &&
288            ((get_dumpable(mm) != SUID_DUMP_USER) &&
289             !ptrace_has_cap(mm->user_ns, mode)))
290            return -EPERM;
291
292        return security_ptrace_access_check(task, mode);
293}
294
295bool ptrace_may_access(struct task_struct *task, unsigned int mode)
296{
297        int err;
298        task_lock(task);
299        err = __ptrace_may_access(task, mode);
300        task_unlock(task);
301        return !err;
302}
303
304static int ptrace_attach(struct task_struct *task, long request,
305                         unsigned long addr,
306                         unsigned long flags)
307{
308        bool seize = (request == PTRACE_SEIZE);
309        int retval;
310
311        retval = -EIO;
312        if (seize) {
313                if (addr != 0)
314                        goto out;
315                if (flags & ~(unsigned long)PTRACE_O_MASK)
316                        goto out;
317                flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
318        } else {
319                flags = PT_PTRACED;
320        }
321
322        audit_ptrace(task);
323
324        retval = -EPERM;
325        if (unlikely(task->flags & PF_KTHREAD))
326                goto out;
327        if (same_thread_group(task, current))
328                goto out;
329
330        /*
331         * Protect exec's credential calculations against our interference;
332         * SUID, SGID and LSM creds get determined differently
333         * under ptrace.
334         */
335        retval = -ERESTARTNOINTR;
336        if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
337                goto out;
338
339        task_lock(task);
340        retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
341        task_unlock(task);
342        if (retval)
343                goto unlock_creds;
344
345        write_lock_irq(&tasklist_lock);
346        retval = -EPERM;
347        if (unlikely(task->exit_state))
348                goto unlock_tasklist;
349        if (task->ptrace)
350                goto unlock_tasklist;
351
352        if (seize)
353                flags |= PT_SEIZED;
354        task->ptrace = flags;
355
356        __ptrace_link(task, current);
357
358        /* SEIZE doesn't trap tracee on attach */
359        if (!seize)
360                send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
361
362        spin_lock(&task->sighand->siglock);
363
364        /*
365         * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
366         * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
367         * will be cleared if the child completes the transition or any
368         * event which clears the group stop states happens.  We'll wait
369         * for the transition to complete before returning from this
370         * function.
371         *
372         * This hides STOPPED -> RUNNING -> TRACED transition from the
373         * attaching thread but a different thread in the same group can
374         * still observe the transient RUNNING state.  IOW, if another
375         * thread's WNOHANG wait(2) on the stopped tracee races against
376         * ATTACH, the wait(2) may fail due to the transient RUNNING.
377         *
378         * The following task_is_stopped() test is safe as both transitions
379         * in and out of STOPPED are protected by siglock.
380         */
381        if (task_is_stopped(task) &&
382            task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
383                signal_wake_up_state(task, __TASK_STOPPED);
384
385        spin_unlock(&task->sighand->siglock);
386
387        retval = 0;
388unlock_tasklist:
389        write_unlock_irq(&tasklist_lock);
390unlock_creds:
391        mutex_unlock(&task->signal->cred_guard_mutex);
392out:
393        if (!retval) {
394                wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
395                            TASK_UNINTERRUPTIBLE);
396                proc_ptrace_connector(task, PTRACE_ATTACH);
397        }
398
399        return retval;
400}
401
402/**
403 * ptrace_traceme  --  helper for PTRACE_TRACEME
404 *
405 * Performs checks and sets PT_PTRACED.
406 * Should be used by all ptrace implementations for PTRACE_TRACEME.
407 */
408static int ptrace_traceme(void)
409{
410        int ret = -EPERM;
411
412        write_lock_irq(&tasklist_lock);
413        /* Are we already being traced? */
414        if (!current->ptrace) {
415                ret = security_ptrace_traceme(current->parent);
416                /*
417                 * Check PF_EXITING to ensure ->real_parent has not passed
418                 * exit_ptrace(). Otherwise we don't report the error but
419                 * pretend ->real_parent untraces us right after return.
420                 */
421                if (!ret && !(current->real_parent->flags & PF_EXITING)) {
422                        current->ptrace = PT_PTRACED;
423                        __ptrace_link(current, current->real_parent);
424                }
425        }
426        write_unlock_irq(&tasklist_lock);
427
428        return ret;
429}
430
431/*
432 * Called with irqs disabled, returns true if childs should reap themselves.
433 */
434static int ignoring_children(struct sighand_struct *sigh)
435{
436        int ret;
437        spin_lock(&sigh->siglock);
438        ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
439              (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
440        spin_unlock(&sigh->siglock);
441        return ret;
442}
443
444/*
445 * Called with tasklist_lock held for writing.
446 * Unlink a traced task, and clean it up if it was a traced zombie.
447 * Return true if it needs to be reaped with release_task().
448 * (We can't call release_task() here because we already hold tasklist_lock.)
449 *
450 * If it's a zombie, our attachedness prevented normal parent notification
451 * or self-reaping.  Do notification now if it would have happened earlier.
452 * If it should reap itself, return true.
453 *
454 * If it's our own child, there is no notification to do. But if our normal
455 * children self-reap, then this child was prevented by ptrace and we must
456 * reap it now, in that case we must also wake up sub-threads sleeping in
457 * do_wait().
458 */
459static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
460{
461        bool dead;
462
463        __ptrace_unlink(p);
464
465        if (p->exit_state != EXIT_ZOMBIE)
466                return false;
467
468        dead = !thread_group_leader(p);
469
470        if (!dead && thread_group_empty(p)) {
471                if (!same_thread_group(p->real_parent, tracer))
472                        dead = do_notify_parent(p, p->exit_signal);
473                else if (ignoring_children(tracer->sighand)) {
474                        __wake_up_parent(p, tracer);
475                        dead = true;
476                }
477        }
478        /* Mark it as in the process of being reaped. */
479        if (dead)
480                p->exit_state = EXIT_DEAD;
481        return dead;
482}
483
484static int ptrace_detach(struct task_struct *child, unsigned int data)
485{
486        if (!valid_signal(data))
487                return -EIO;
488
489        /* Architecture-specific hardware disable .. */
490        ptrace_disable(child);
491        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
492
493        write_lock_irq(&tasklist_lock);
494        /*
495         * We rely on ptrace_freeze_traced(). It can't be killed and
496         * untraced by another thread, it can't be a zombie.
497         */
498        WARN_ON(!child->ptrace || child->exit_state);
499        /*
500         * tasklist_lock avoids the race with wait_task_stopped(), see
501         * the comment in ptrace_resume().
502         */
503        child->exit_code = data;
504        __ptrace_detach(current, child);
505        write_unlock_irq(&tasklist_lock);
506
507        proc_ptrace_connector(child, PTRACE_DETACH);
508
509        return 0;
510}
511
512/*
513 * Detach all tasks we were using ptrace on. Called with tasklist held
514 * for writing.
515 */
516void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
517{
518        struct task_struct *p, *n;
519
520        list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
521                if (unlikely(p->ptrace & PT_EXITKILL))
522                        send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
523
524                if (__ptrace_detach(tracer, p))
525                        list_add(&p->ptrace_entry, dead);
526        }
527}
528
529int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
530{
531        int copied = 0;
532
533        while (len > 0) {
534                char buf[128];
535                int this_len, retval;
536
537                this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
538                retval = access_process_vm(tsk, src, buf, this_len, 0);
539                if (!retval) {
540                        if (copied)
541                                break;
542                        return -EIO;
543                }
544                if (copy_to_user(dst, buf, retval))
545                        return -EFAULT;
546                copied += retval;
547                src += retval;
548                dst += retval;
549                len -= retval;
550        }
551        return copied;
552}
553
554int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
555{
556        int copied = 0;
557
558        while (len > 0) {
559                char buf[128];
560                int this_len, retval;
561
562                this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
563                if (copy_from_user(buf, src, this_len))
564                        return -EFAULT;
565                retval = access_process_vm(tsk, dst, buf, this_len, 1);
566                if (!retval) {
567                        if (copied)
568                                break;
569                        return -EIO;
570                }
571                copied += retval;
572                src += retval;
573                dst += retval;
574                len -= retval;
575        }
576        return copied;
577}
578
579static int ptrace_setoptions(struct task_struct *child, unsigned long data)
580{
581        unsigned flags;
582
583        if (data & ~(unsigned long)PTRACE_O_MASK)
584                return -EINVAL;
585
586        if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
587                if (!config_enabled(CONFIG_CHECKPOINT_RESTORE) ||
588                    !config_enabled(CONFIG_SECCOMP))
589                        return -EINVAL;
590
591                if (!capable(CAP_SYS_ADMIN))
592                        return -EPERM;
593
594                if (seccomp_mode(&current->seccomp) != SECCOMP_MODE_DISABLED ||
595                    current->ptrace & PT_SUSPEND_SECCOMP)
596                        return -EPERM;
597        }
598
599        /* Avoid intermediate state when all opts are cleared */
600        flags = child->ptrace;
601        flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
602        flags |= (data << PT_OPT_FLAG_SHIFT);
603        child->ptrace = flags;
604
605        return 0;
606}
607
608static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
609{
610        unsigned long flags;
611        int error = -ESRCH;
612
613        if (lock_task_sighand(child, &flags)) {
614                error = -EINVAL;
615                if (likely(child->last_siginfo != NULL)) {
616                        *info = *child->last_siginfo;
617                        error = 0;
618                }
619                unlock_task_sighand(child, &flags);
620        }
621        return error;
622}
623
624static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
625{
626        unsigned long flags;
627        int error = -ESRCH;
628
629        if (lock_task_sighand(child, &flags)) {
630                error = -EINVAL;
631                if (likely(child->last_siginfo != NULL)) {
632                        *child->last_siginfo = *info;
633                        error = 0;
634                }
635                unlock_task_sighand(child, &flags);
636        }
637        return error;
638}
639
640static int ptrace_peek_siginfo(struct task_struct *child,
641                                unsigned long addr,
642                                unsigned long data)
643{
644        struct ptrace_peeksiginfo_args arg;
645        struct sigpending *pending;
646        struct sigqueue *q;
647        int ret, i;
648
649        ret = copy_from_user(&arg, (void __user *) addr,
650                                sizeof(struct ptrace_peeksiginfo_args));
651        if (ret)
652                return -EFAULT;
653
654        if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
655                return -EINVAL; /* unknown flags */
656
657        if (arg.nr < 0)
658                return -EINVAL;
659
660        if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
661                pending = &child->signal->shared_pending;
662        else
663                pending = &child->pending;
664
665        for (i = 0; i < arg.nr; ) {
666                siginfo_t info;
667                s32 off = arg.off + i;
668
669                spin_lock_irq(&child->sighand->siglock);
670                list_for_each_entry(q, &pending->list, list) {
671                        if (!off--) {
672                                copy_siginfo(&info, &q->info);
673                                break;
674                        }
675                }
676                spin_unlock_irq(&child->sighand->siglock);
677
678                if (off >= 0) /* beyond the end of the list */
679                        break;
680
681#ifdef CONFIG_COMPAT
682                if (unlikely(is_compat_task())) {
683                        compat_siginfo_t __user *uinfo = compat_ptr(data);
684
685                        if (copy_siginfo_to_user32(uinfo, &info) ||
686                            __put_user(info.si_code, &uinfo->si_code)) {
687                                ret = -EFAULT;
688                                break;
689                        }
690
691                } else
692#endif
693                {
694                        siginfo_t __user *uinfo = (siginfo_t __user *) data;
695
696                        if (copy_siginfo_to_user(uinfo, &info) ||
697                            __put_user(info.si_code, &uinfo->si_code)) {
698                                ret = -EFAULT;
699                                break;
700                        }
701                }
702
703                data += sizeof(siginfo_t);
704                i++;
705
706                if (signal_pending(current))
707                        break;
708
709                cond_resched();
710        }
711
712        if (i > 0)
713                return i;
714
715        return ret;
716}
717
718#ifdef PTRACE_SINGLESTEP
719#define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
720#else
721#define is_singlestep(request)          0
722#endif
723
724#ifdef PTRACE_SINGLEBLOCK
725#define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
726#else
727#define is_singleblock(request)         0
728#endif
729
730#ifdef PTRACE_SYSEMU
731#define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
732#else
733#define is_sysemu_singlestep(request)   0
734#endif
735
736static int ptrace_resume(struct task_struct *child, long request,
737                         unsigned long data)
738{
739        bool need_siglock;
740
741        if (!valid_signal(data))
742                return -EIO;
743
744        if (request == PTRACE_SYSCALL)
745                set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
746        else
747                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
748
749#ifdef TIF_SYSCALL_EMU
750        if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
751                set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
752        else
753                clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
754#endif
755
756        if (is_singleblock(request)) {
757                if (unlikely(!arch_has_block_step()))
758                        return -EIO;
759                user_enable_block_step(child);
760        } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
761                if (unlikely(!arch_has_single_step()))
762                        return -EIO;
763                user_enable_single_step(child);
764        } else {
765                user_disable_single_step(child);
766        }
767
768        /*
769         * Change ->exit_code and ->state under siglock to avoid the race
770         * with wait_task_stopped() in between; a non-zero ->exit_code will
771         * wrongly look like another report from tracee.
772         *
773         * Note that we need siglock even if ->exit_code == data and/or this
774         * status was not reported yet, the new status must not be cleared by
775         * wait_task_stopped() after resume.
776         *
777         * If data == 0 we do not care if wait_task_stopped() reports the old
778         * status and clears the code too; this can't race with the tracee, it
779         * takes siglock after resume.
780         */
781        need_siglock = data && !thread_group_empty(current);
782        if (need_siglock)
783                spin_lock_irq(&child->sighand->siglock);
784        child->exit_code = data;
785        wake_up_state(child, __TASK_TRACED);
786        if (need_siglock)
787                spin_unlock_irq(&child->sighand->siglock);
788
789        return 0;
790}
791
792#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
793
794static const struct user_regset *
795find_regset(const struct user_regset_view *view, unsigned int type)
796{
797        const struct user_regset *regset;
798        int n;
799
800        for (n = 0; n < view->n; ++n) {
801                regset = view->regsets + n;
802                if (regset->core_note_type == type)
803                        return regset;
804        }
805
806        return NULL;
807}
808
809static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
810                         struct iovec *kiov)
811{
812        const struct user_regset_view *view = task_user_regset_view(task);
813        const struct user_regset *regset = find_regset(view, type);
814        int regset_no;
815
816        if (!regset || (kiov->iov_len % regset->size) != 0)
817                return -EINVAL;
818
819        regset_no = regset - view->regsets;
820        kiov->iov_len = min(kiov->iov_len,
821                            (__kernel_size_t) (regset->n * regset->size));
822
823        if (req == PTRACE_GETREGSET)
824                return copy_regset_to_user(task, view, regset_no, 0,
825                                           kiov->iov_len, kiov->iov_base);
826        else
827                return copy_regset_from_user(task, view, regset_no, 0,
828                                             kiov->iov_len, kiov->iov_base);
829}
830
831/*
832 * This is declared in linux/regset.h and defined in machine-dependent
833 * code.  We put the export here, near the primary machine-neutral use,
834 * to ensure no machine forgets it.
835 */
836EXPORT_SYMBOL_GPL(task_user_regset_view);
837#endif
838
839int ptrace_request(struct task_struct *child, long request,
840                   unsigned long addr, unsigned long data)
841{
842        bool seized = child->ptrace & PT_SEIZED;
843        int ret = -EIO;
844        siginfo_t siginfo, *si;
845        void __user *datavp = (void __user *) data;
846        unsigned long __user *datalp = datavp;
847        unsigned long flags;
848
849        switch (request) {
850        case PTRACE_PEEKTEXT:
851        case PTRACE_PEEKDATA:
852                return generic_ptrace_peekdata(child, addr, data);
853        case PTRACE_POKETEXT:
854        case PTRACE_POKEDATA:
855                return generic_ptrace_pokedata(child, addr, data);
856
857#ifdef PTRACE_OLDSETOPTIONS
858        case PTRACE_OLDSETOPTIONS:
859#endif
860        case PTRACE_SETOPTIONS:
861                ret = ptrace_setoptions(child, data);
862                break;
863        case PTRACE_GETEVENTMSG:
864                ret = put_user(child->ptrace_message, datalp);
865                break;
866
867        case PTRACE_PEEKSIGINFO:
868                ret = ptrace_peek_siginfo(child, addr, data);
869                break;
870
871        case PTRACE_GETSIGINFO:
872                ret = ptrace_getsiginfo(child, &siginfo);
873                if (!ret)
874                        ret = copy_siginfo_to_user(datavp, &siginfo);
875                break;
876
877        case PTRACE_SETSIGINFO:
878                if (copy_from_user(&siginfo, datavp, sizeof siginfo))
879                        ret = -EFAULT;
880                else
881                        ret = ptrace_setsiginfo(child, &siginfo);
882                break;
883
884        case PTRACE_GETSIGMASK:
885                if (addr != sizeof(sigset_t)) {
886                        ret = -EINVAL;
887                        break;
888                }
889
890                if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
891                        ret = -EFAULT;
892                else
893                        ret = 0;
894
895                break;
896
897        case PTRACE_SETSIGMASK: {
898                sigset_t new_set;
899
900                if (addr != sizeof(sigset_t)) {
901                        ret = -EINVAL;
902                        break;
903                }
904
905                if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
906                        ret = -EFAULT;
907                        break;
908                }
909
910                sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
911
912                /*
913                 * Every thread does recalc_sigpending() after resume, so
914                 * retarget_shared_pending() and recalc_sigpending() are not
915                 * called here.
916                 */
917                spin_lock_irq(&child->sighand->siglock);
918                child->blocked = new_set;
919                spin_unlock_irq(&child->sighand->siglock);
920
921                ret = 0;
922                break;
923        }
924
925        case PTRACE_INTERRUPT:
926                /*
927                 * Stop tracee without any side-effect on signal or job
928                 * control.  At least one trap is guaranteed to happen
929                 * after this request.  If @child is already trapped, the
930                 * current trap is not disturbed and another trap will
931                 * happen after the current trap is ended with PTRACE_CONT.
932                 *
933                 * The actual trap might not be PTRACE_EVENT_STOP trap but
934                 * the pending condition is cleared regardless.
935                 */
936                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
937                        break;
938
939                /*
940                 * INTERRUPT doesn't disturb existing trap sans one
941                 * exception.  If ptracer issued LISTEN for the current
942                 * STOP, this INTERRUPT should clear LISTEN and re-trap
943                 * tracee into STOP.
944                 */
945                if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
946                        ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
947
948                unlock_task_sighand(child, &flags);
949                ret = 0;
950                break;
951
952        case PTRACE_LISTEN:
953                /*
954                 * Listen for events.  Tracee must be in STOP.  It's not
955                 * resumed per-se but is not considered to be in TRACED by
956                 * wait(2) or ptrace(2).  If an async event (e.g. group
957                 * stop state change) happens, tracee will enter STOP trap
958                 * again.  Alternatively, ptracer can issue INTERRUPT to
959                 * finish listening and re-trap tracee into STOP.
960                 */
961                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
962                        break;
963
964                si = child->last_siginfo;
965                if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
966                        child->jobctl |= JOBCTL_LISTENING;
967                        /*
968                         * If NOTIFY is set, it means event happened between
969                         * start of this trap and now.  Trigger re-trap.
970                         */
971                        if (child->jobctl & JOBCTL_TRAP_NOTIFY)
972                                ptrace_signal_wake_up(child, true);
973                        ret = 0;
974                }
975                unlock_task_sighand(child, &flags);
976                break;
977
978        case PTRACE_DETACH:      /* detach a process that was attached. */
979                ret = ptrace_detach(child, data);
980                break;
981
982#ifdef CONFIG_BINFMT_ELF_FDPIC
983        case PTRACE_GETFDPIC: {
984                struct mm_struct *mm = get_task_mm(child);
985                unsigned long tmp = 0;
986
987                ret = -ESRCH;
988                if (!mm)
989                        break;
990
991                switch (addr) {
992                case PTRACE_GETFDPIC_EXEC:
993                        tmp = mm->context.exec_fdpic_loadmap;
994                        break;
995                case PTRACE_GETFDPIC_INTERP:
996                        tmp = mm->context.interp_fdpic_loadmap;
997                        break;
998                default:
999                        break;
1000                }
1001                mmput(mm);
1002
1003                ret = put_user(tmp, datalp);
1004                break;
1005        }
1006#endif
1007
1008#ifdef PTRACE_SINGLESTEP
1009        case PTRACE_SINGLESTEP:
1010#endif
1011#ifdef PTRACE_SINGLEBLOCK
1012        case PTRACE_SINGLEBLOCK:
1013#endif
1014#ifdef PTRACE_SYSEMU
1015        case PTRACE_SYSEMU:
1016        case PTRACE_SYSEMU_SINGLESTEP:
1017#endif
1018        case PTRACE_SYSCALL:
1019        case PTRACE_CONT:
1020                return ptrace_resume(child, request, data);
1021
1022        case PTRACE_KILL:
1023                if (child->exit_state)  /* already dead */
1024                        return 0;
1025                return ptrace_resume(child, request, SIGKILL);
1026
1027#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1028        case PTRACE_GETREGSET:
1029        case PTRACE_SETREGSET: {
1030                struct iovec kiov;
1031                struct iovec __user *uiov = datavp;
1032
1033                if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1034                        return -EFAULT;
1035
1036                if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1037                    __get_user(kiov.iov_len, &uiov->iov_len))
1038                        return -EFAULT;
1039
1040                ret = ptrace_regset(child, request, addr, &kiov);
1041                if (!ret)
1042                        ret = __put_user(kiov.iov_len, &uiov->iov_len);
1043                break;
1044        }
1045#endif
1046
1047        case PTRACE_SECCOMP_GET_FILTER:
1048                ret = seccomp_get_filter(child, addr, datavp);
1049                break;
1050
1051        default:
1052                break;
1053        }
1054
1055        return ret;
1056}
1057
1058static struct task_struct *ptrace_get_task_struct(pid_t pid)
1059{
1060        struct task_struct *child;
1061
1062        rcu_read_lock();
1063        child = find_task_by_vpid(pid);
1064        if (child)
1065                get_task_struct(child);
1066        rcu_read_unlock();
1067
1068        if (!child)
1069                return ERR_PTR(-ESRCH);
1070        return child;
1071}
1072
1073#ifndef arch_ptrace_attach
1074#define arch_ptrace_attach(child)       do { } while (0)
1075#endif
1076
1077SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1078                unsigned long, data)
1079{
1080        struct task_struct *child;
1081        long ret;
1082
1083        if (request == PTRACE_TRACEME) {
1084                ret = ptrace_traceme();
1085                if (!ret)
1086                        arch_ptrace_attach(current);
1087                goto out;
1088        }
1089
1090        child = ptrace_get_task_struct(pid);
1091        if (IS_ERR(child)) {
1092                ret = PTR_ERR(child);
1093                goto out;
1094        }
1095
1096        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1097                ret = ptrace_attach(child, request, addr, data);
1098                /*
1099                 * Some architectures need to do book-keeping after
1100                 * a ptrace attach.
1101                 */
1102                if (!ret)
1103                        arch_ptrace_attach(child);
1104                goto out_put_task_struct;
1105        }
1106
1107        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1108                                  request == PTRACE_INTERRUPT);
1109        if (ret < 0)
1110                goto out_put_task_struct;
1111
1112        ret = arch_ptrace(child, request, addr, data);
1113        if (ret || request != PTRACE_DETACH)
1114                ptrace_unfreeze_traced(child);
1115
1116 out_put_task_struct:
1117        put_task_struct(child);
1118 out:
1119        return ret;
1120}
1121
1122int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1123                            unsigned long data)
1124{
1125        unsigned long tmp;
1126        int copied;
1127
1128        copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
1129        if (copied != sizeof(tmp))
1130                return -EIO;
1131        return put_user(tmp, (unsigned long __user *)data);
1132}
1133
1134int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1135                            unsigned long data)
1136{
1137        int copied;
1138
1139        copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
1140        return (copied == sizeof(data)) ? 0 : -EIO;
1141}
1142
1143#if defined CONFIG_COMPAT
1144
1145int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1146                          compat_ulong_t addr, compat_ulong_t data)
1147{
1148        compat_ulong_t __user *datap = compat_ptr(data);
1149        compat_ulong_t word;
1150        siginfo_t siginfo;
1151        int ret;
1152
1153        switch (request) {
1154        case PTRACE_PEEKTEXT:
1155        case PTRACE_PEEKDATA:
1156                ret = access_process_vm(child, addr, &word, sizeof(word), 0);
1157                if (ret != sizeof(word))
1158                        ret = -EIO;
1159                else
1160                        ret = put_user(word, datap);
1161                break;
1162
1163        case PTRACE_POKETEXT:
1164        case PTRACE_POKEDATA:
1165                ret = access_process_vm(child, addr, &data, sizeof(data), 1);
1166                ret = (ret != sizeof(data) ? -EIO : 0);
1167                break;
1168
1169        case PTRACE_GETEVENTMSG:
1170                ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1171                break;
1172
1173        case PTRACE_GETSIGINFO:
1174                ret = ptrace_getsiginfo(child, &siginfo);
1175                if (!ret)
1176                        ret = copy_siginfo_to_user32(
1177                                (struct compat_siginfo __user *) datap,
1178                                &siginfo);
1179                break;
1180
1181        case PTRACE_SETSIGINFO:
1182                memset(&siginfo, 0, sizeof siginfo);
1183                if (copy_siginfo_from_user32(
1184                            &siginfo, (struct compat_siginfo __user *) datap))
1185                        ret = -EFAULT;
1186                else
1187                        ret = ptrace_setsiginfo(child, &siginfo);
1188                break;
1189#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1190        case PTRACE_GETREGSET:
1191        case PTRACE_SETREGSET:
1192        {
1193                struct iovec kiov;
1194                struct compat_iovec __user *uiov =
1195                        (struct compat_iovec __user *) datap;
1196                compat_uptr_t ptr;
1197                compat_size_t len;
1198
1199                if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1200                        return -EFAULT;
1201
1202                if (__get_user(ptr, &uiov->iov_base) ||
1203                    __get_user(len, &uiov->iov_len))
1204                        return -EFAULT;
1205
1206                kiov.iov_base = compat_ptr(ptr);
1207                kiov.iov_len = len;
1208
1209                ret = ptrace_regset(child, request, addr, &kiov);
1210                if (!ret)
1211                        ret = __put_user(kiov.iov_len, &uiov->iov_len);
1212                break;
1213        }
1214#endif
1215
1216        default:
1217                ret = ptrace_request(child, request, addr, data);
1218        }
1219
1220        return ret;
1221}
1222
1223COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1224                       compat_long_t, addr, compat_long_t, data)
1225{
1226        struct task_struct *child;
1227        long ret;
1228
1229        if (request == PTRACE_TRACEME) {
1230                ret = ptrace_traceme();
1231                goto out;
1232        }
1233
1234        child = ptrace_get_task_struct(pid);
1235        if (IS_ERR(child)) {
1236                ret = PTR_ERR(child);
1237                goto out;
1238        }
1239
1240        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1241                ret = ptrace_attach(child, request, addr, data);
1242                /*
1243                 * Some architectures need to do book-keeping after
1244                 * a ptrace attach.
1245                 */
1246                if (!ret)
1247                        arch_ptrace_attach(child);
1248                goto out_put_task_struct;
1249        }
1250
1251        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1252                                  request == PTRACE_INTERRUPT);
1253        if (!ret) {
1254                ret = compat_arch_ptrace(child, request, addr, data);
1255                if (ret || request != PTRACE_DETACH)
1256                        ptrace_unfreeze_traced(child);
1257        }
1258
1259 out_put_task_struct:
1260        put_task_struct(child);
1261 out:
1262        return ret;
1263}
1264#endif  /* CONFIG_COMPAT */
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