Root/kernel/ptrace.c

1/*
2 * linux/kernel/ptrace.c
3 *
4 * (C) Copyright 1999 Linus Torvalds
5 *
6 * Common interfaces for "ptrace()" which we do not want
7 * to continually duplicate across every architecture.
8 */
9
10#include <linux/capability.h>
11#include <linux/export.h>
12#include <linux/sched.h>
13#include <linux/errno.h>
14#include <linux/mm.h>
15#include <linux/highmem.h>
16#include <linux/pagemap.h>
17#include <linux/ptrace.h>
18#include <linux/security.h>
19#include <linux/signal.h>
20#include <linux/uio.h>
21#include <linux/audit.h>
22#include <linux/pid_namespace.h>
23#include <linux/syscalls.h>
24#include <linux/uaccess.h>
25#include <linux/regset.h>
26#include <linux/hw_breakpoint.h>
27#include <linux/cn_proc.h>
28#include <linux/compat.h>
29
30
31static int ptrace_trapping_sleep_fn(void *flags)
32{
33    schedule();
34    return 0;
35}
36
37/*
38 * ptrace a task: make the debugger its new parent and
39 * move it to the ptrace list.
40 *
41 * Must be called with the tasklist lock write-held.
42 */
43void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
44{
45    BUG_ON(!list_empty(&child->ptrace_entry));
46    list_add(&child->ptrace_entry, &new_parent->ptraced);
47    child->parent = new_parent;
48}
49
50/**
51 * __ptrace_unlink - unlink ptracee and restore its execution state
52 * @child: ptracee to be unlinked
53 *
54 * Remove @child from the ptrace list, move it back to the original parent,
55 * and restore the execution state so that it conforms to the group stop
56 * state.
57 *
58 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
59 * exiting. For PTRACE_DETACH, unless the ptracee has been killed between
60 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
61 * If the ptracer is exiting, the ptracee can be in any state.
62 *
63 * After detach, the ptracee should be in a state which conforms to the
64 * group stop. If the group is stopped or in the process of stopping, the
65 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
66 * up from TASK_TRACED.
67 *
68 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
69 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
70 * to but in the opposite direction of what happens while attaching to a
71 * stopped task. However, in this direction, the intermediate RUNNING
72 * state is not hidden even from the current ptracer and if it immediately
73 * re-attaches and performs a WNOHANG wait(2), it may fail.
74 *
75 * CONTEXT:
76 * write_lock_irq(tasklist_lock)
77 */
78void __ptrace_unlink(struct task_struct *child)
79{
80    BUG_ON(!child->ptrace);
81
82    child->ptrace = 0;
83    child->parent = child->real_parent;
84    list_del_init(&child->ptrace_entry);
85
86    spin_lock(&child->sighand->siglock);
87
88    /*
89     * Clear all pending traps and TRAPPING. TRAPPING should be
90     * cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly.
91     */
92    task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
93    task_clear_jobctl_trapping(child);
94
95    /*
96     * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
97     * @child isn't dead.
98     */
99    if (!(child->flags & PF_EXITING) &&
100        (child->signal->flags & SIGNAL_STOP_STOPPED ||
101         child->signal->group_stop_count)) {
102        child->jobctl |= JOBCTL_STOP_PENDING;
103
104        /*
105         * This is only possible if this thread was cloned by the
106         * traced task running in the stopped group, set the signal
107         * for the future reports.
108         * FIXME: we should change ptrace_init_task() to handle this
109         * case.
110         */
111        if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
112            child->jobctl |= SIGSTOP;
113    }
114
115    /*
116     * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
117     * @child in the butt. Note that @resume should be used iff @child
118     * is in TASK_TRACED; otherwise, we might unduly disrupt
119     * TASK_KILLABLE sleeps.
120     */
121    if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
122        ptrace_signal_wake_up(child, true);
123
124    spin_unlock(&child->sighand->siglock);
125}
126
127/* Ensure that nothing can wake it up, even SIGKILL */
128static bool ptrace_freeze_traced(struct task_struct *task)
129{
130    bool ret = false;
131
132    /* Lockless, nobody but us can set this flag */
133    if (task->jobctl & JOBCTL_LISTENING)
134        return ret;
135
136    spin_lock_irq(&task->sighand->siglock);
137    if (task_is_traced(task) && !__fatal_signal_pending(task)) {
138        task->state = __TASK_TRACED;
139        ret = true;
140    }
141    spin_unlock_irq(&task->sighand->siglock);
142
143    return ret;
144}
145
146static void ptrace_unfreeze_traced(struct task_struct *task)
147{
148    if (task->state != __TASK_TRACED)
149        return;
150
151    WARN_ON(!task->ptrace || task->parent != current);
152
153    spin_lock_irq(&task->sighand->siglock);
154    if (__fatal_signal_pending(task))
155        wake_up_state(task, __TASK_TRACED);
156    else
157        task->state = TASK_TRACED;
158    spin_unlock_irq(&task->sighand->siglock);
159}
160
161/**
162 * ptrace_check_attach - check whether ptracee is ready for ptrace operation
163 * @child: ptracee to check for
164 * @ignore_state: don't check whether @child is currently %TASK_TRACED
165 *
166 * Check whether @child is being ptraced by %current and ready for further
167 * ptrace operations. If @ignore_state is %false, @child also should be in
168 * %TASK_TRACED state and on return the child is guaranteed to be traced
169 * and not executing. If @ignore_state is %true, @child can be in any
170 * state.
171 *
172 * CONTEXT:
173 * Grabs and releases tasklist_lock and @child->sighand->siglock.
174 *
175 * RETURNS:
176 * 0 on success, -ESRCH if %child is not ready.
177 */
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
229    /* May we inspect the given task?
230     * This check is used both for attaching with ptrace
231     * and for allowing access to sensitive information in /proc.
232     *
233     * ptrace_attach denies several cases that /proc allows
234     * because setting up the necessary parent/child relationship
235     * or halting the specified task is impossible.
236     */
237    int dumpable = 0;
238    /* Don't let security modules deny introspection */
239    if (same_thread_group(task, current))
240        return 0;
241    rcu_read_lock();
242    tcred = __task_cred(task);
243    if (uid_eq(cred->uid, tcred->euid) &&
244        uid_eq(cred->uid, tcred->suid) &&
245        uid_eq(cred->uid, tcred->uid) &&
246        gid_eq(cred->gid, tcred->egid) &&
247        gid_eq(cred->gid, tcred->sgid) &&
248        gid_eq(cred->gid, tcred->gid))
249        goto ok;
250    if (ptrace_has_cap(tcred->user_ns, mode))
251        goto ok;
252    rcu_read_unlock();
253    return -EPERM;
254ok:
255    rcu_read_unlock();
256    smp_rmb();
257    if (task->mm)
258        dumpable = get_dumpable(task->mm);
259    rcu_read_lock();
260    if (dumpable != SUID_DUMP_USER &&
261        !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {
262        rcu_read_unlock();
263        return -EPERM;
264    }
265    rcu_read_unlock();
266
267    return security_ptrace_access_check(task, mode);
268}
269
270bool ptrace_may_access(struct task_struct *task, unsigned int mode)
271{
272    int err;
273    task_lock(task);
274    err = __ptrace_may_access(task, mode);
275    task_unlock(task);
276    return !err;
277}
278
279static int ptrace_attach(struct task_struct *task, long request,
280             unsigned long addr,
281             unsigned long flags)
282{
283    bool seize = (request == PTRACE_SEIZE);
284    int retval;
285
286    retval = -EIO;
287    if (seize) {
288        if (addr != 0)
289            goto out;
290        if (flags & ~(unsigned long)PTRACE_O_MASK)
291            goto out;
292        flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
293    } else {
294        flags = PT_PTRACED;
295    }
296
297    audit_ptrace(task);
298
299    retval = -EPERM;
300    if (unlikely(task->flags & PF_KTHREAD))
301        goto out;
302    if (same_thread_group(task, current))
303        goto out;
304
305    /*
306     * Protect exec's credential calculations against our interference;
307     * SUID, SGID and LSM creds get determined differently
308     * under ptrace.
309     */
310    retval = -ERESTARTNOINTR;
311    if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
312        goto out;
313
314    task_lock(task);
315    retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
316    task_unlock(task);
317    if (retval)
318        goto unlock_creds;
319
320    write_lock_irq(&tasklist_lock);
321    retval = -EPERM;
322    if (unlikely(task->exit_state))
323        goto unlock_tasklist;
324    if (task->ptrace)
325        goto unlock_tasklist;
326
327    if (seize)
328        flags |= PT_SEIZED;
329    rcu_read_lock();
330    if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))
331        flags |= PT_PTRACE_CAP;
332    rcu_read_unlock();
333    task->ptrace = flags;
334
335    __ptrace_link(task, current);
336
337    /* SEIZE doesn't trap tracee on attach */
338    if (!seize)
339        send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
340
341    spin_lock(&task->sighand->siglock);
342
343    /*
344     * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
345     * TRAPPING, and kick it so that it transits to TRACED. TRAPPING
346     * will be cleared if the child completes the transition or any
347     * event which clears the group stop states happens. We'll wait
348     * for the transition to complete before returning from this
349     * function.
350     *
351     * This hides STOPPED -> RUNNING -> TRACED transition from the
352     * attaching thread but a different thread in the same group can
353     * still observe the transient RUNNING state. IOW, if another
354     * thread's WNOHANG wait(2) on the stopped tracee races against
355     * ATTACH, the wait(2) may fail due to the transient RUNNING.
356     *
357     * The following task_is_stopped() test is safe as both transitions
358     * in and out of STOPPED are protected by siglock.
359     */
360    if (task_is_stopped(task) &&
361        task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
362        signal_wake_up_state(task, __TASK_STOPPED);
363
364    spin_unlock(&task->sighand->siglock);
365
366    retval = 0;
367unlock_tasklist:
368    write_unlock_irq(&tasklist_lock);
369unlock_creds:
370    mutex_unlock(&task->signal->cred_guard_mutex);
371out:
372    if (!retval) {
373        wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
374                ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
375        proc_ptrace_connector(task, PTRACE_ATTACH);
376    }
377
378    return retval;
379}
380
381/**
382 * ptrace_traceme -- helper for PTRACE_TRACEME
383 *
384 * Performs checks and sets PT_PTRACED.
385 * Should be used by all ptrace implementations for PTRACE_TRACEME.
386 */
387static int ptrace_traceme(void)
388{
389    int ret = -EPERM;
390
391    write_lock_irq(&tasklist_lock);
392    /* Are we already being traced? */
393    if (!current->ptrace) {
394        ret = security_ptrace_traceme(current->parent);
395        /*
396         * Check PF_EXITING to ensure ->real_parent has not passed
397         * exit_ptrace(). Otherwise we don't report the error but
398         * pretend ->real_parent untraces us right after return.
399         */
400        if (!ret && !(current->real_parent->flags & PF_EXITING)) {
401            current->ptrace = PT_PTRACED;
402            __ptrace_link(current, current->real_parent);
403        }
404    }
405    write_unlock_irq(&tasklist_lock);
406
407    return ret;
408}
409
410/*
411 * Called with irqs disabled, returns true if childs should reap themselves.
412 */
413static int ignoring_children(struct sighand_struct *sigh)
414{
415    int ret;
416    spin_lock(&sigh->siglock);
417    ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
418          (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
419    spin_unlock(&sigh->siglock);
420    return ret;
421}
422
423/*
424 * Called with tasklist_lock held for writing.
425 * Unlink a traced task, and clean it up if it was a traced zombie.
426 * Return true if it needs to be reaped with release_task().
427 * (We can't call release_task() here because we already hold tasklist_lock.)
428 *
429 * If it's a zombie, our attachedness prevented normal parent notification
430 * or self-reaping. Do notification now if it would have happened earlier.
431 * If it should reap itself, return true.
432 *
433 * If it's our own child, there is no notification to do. But if our normal
434 * children self-reap, then this child was prevented by ptrace and we must
435 * reap it now, in that case we must also wake up sub-threads sleeping in
436 * do_wait().
437 */
438static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
439{
440    bool dead;
441
442    __ptrace_unlink(p);
443
444    if (p->exit_state != EXIT_ZOMBIE)
445        return false;
446
447    dead = !thread_group_leader(p);
448
449    if (!dead && thread_group_empty(p)) {
450        if (!same_thread_group(p->real_parent, tracer))
451            dead = do_notify_parent(p, p->exit_signal);
452        else if (ignoring_children(tracer->sighand)) {
453            __wake_up_parent(p, tracer);
454            dead = true;
455        }
456    }
457    /* Mark it as in the process of being reaped. */
458    if (dead)
459        p->exit_state = EXIT_DEAD;
460    return dead;
461}
462
463static int ptrace_detach(struct task_struct *child, unsigned int data)
464{
465    bool dead = false;
466
467    if (!valid_signal(data))
468        return -EIO;
469
470    /* Architecture-specific hardware disable .. */
471    ptrace_disable(child);
472    clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
473
474    write_lock_irq(&tasklist_lock);
475    /*
476     * This child can be already killed. Make sure de_thread() or
477     * our sub-thread doing do_wait() didn't do release_task() yet.
478     */
479    if (child->ptrace) {
480        child->exit_code = data;
481        dead = __ptrace_detach(current, child);
482    }
483    write_unlock_irq(&tasklist_lock);
484
485    proc_ptrace_connector(child, PTRACE_DETACH);
486    if (unlikely(dead))
487        release_task(child);
488
489    return 0;
490}
491
492/*
493 * Detach all tasks we were using ptrace on. Called with tasklist held
494 * for writing, and returns with it held too. But note it can release
495 * and reacquire the lock.
496 */
497void exit_ptrace(struct task_struct *tracer)
498    __releases(&tasklist_lock)
499    __acquires(&tasklist_lock)
500{
501    struct task_struct *p, *n;
502    LIST_HEAD(ptrace_dead);
503
504    if (likely(list_empty(&tracer->ptraced)))
505        return;
506
507    list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
508        if (unlikely(p->ptrace & PT_EXITKILL))
509            send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
510
511        if (__ptrace_detach(tracer, p))
512            list_add(&p->ptrace_entry, &ptrace_dead);
513    }
514
515    write_unlock_irq(&tasklist_lock);
516    BUG_ON(!list_empty(&tracer->ptraced));
517
518    list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
519        list_del_init(&p->ptrace_entry);
520        release_task(p);
521    }
522
523    write_lock_irq(&tasklist_lock);
524}
525
526int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
527{
528    int copied = 0;
529
530    while (len > 0) {
531        char buf[128];
532        int this_len, retval;
533
534        this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
535        retval = access_process_vm(tsk, src, buf, this_len, 0);
536        if (!retval) {
537            if (copied)
538                break;
539            return -EIO;
540        }
541        if (copy_to_user(dst, buf, retval))
542            return -EFAULT;
543        copied += retval;
544        src += retval;
545        dst += retval;
546        len -= retval;
547    }
548    return copied;
549}
550
551int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
552{
553    int copied = 0;
554
555    while (len > 0) {
556        char buf[128];
557        int this_len, retval;
558
559        this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
560        if (copy_from_user(buf, src, this_len))
561            return -EFAULT;
562        retval = access_process_vm(tsk, dst, buf, this_len, 1);
563        if (!retval) {
564            if (copied)
565                break;
566            return -EIO;
567        }
568        copied += retval;
569        src += retval;
570        dst += retval;
571        len -= retval;
572    }
573    return copied;
574}
575
576static int ptrace_setoptions(struct task_struct *child, unsigned long data)
577{
578    unsigned flags;
579
580    if (data & ~(unsigned long)PTRACE_O_MASK)
581        return -EINVAL;
582
583    /* Avoid intermediate state when all opts are cleared */
584    flags = child->ptrace;
585    flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
586    flags |= (data << PT_OPT_FLAG_SHIFT);
587    child->ptrace = flags;
588
589    return 0;
590}
591
592static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
593{
594    unsigned long flags;
595    int error = -ESRCH;
596
597    if (lock_task_sighand(child, &flags)) {
598        error = -EINVAL;
599        if (likely(child->last_siginfo != NULL)) {
600            *info = *child->last_siginfo;
601            error = 0;
602        }
603        unlock_task_sighand(child, &flags);
604    }
605    return error;
606}
607
608static int ptrace_setsiginfo(struct task_struct *child, const 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            *child->last_siginfo = *info;
617            error = 0;
618        }
619        unlock_task_sighand(child, &flags);
620    }
621    return error;
622}
623
624static int ptrace_peek_siginfo(struct task_struct *child,
625                unsigned long addr,
626                unsigned long data)
627{
628    struct ptrace_peeksiginfo_args arg;
629    struct sigpending *pending;
630    struct sigqueue *q;
631    int ret, i;
632
633    ret = copy_from_user(&arg, (void __user *) addr,
634                sizeof(struct ptrace_peeksiginfo_args));
635    if (ret)
636        return -EFAULT;
637
638    if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
639        return -EINVAL; /* unknown flags */
640
641    if (arg.nr < 0)
642        return -EINVAL;
643
644    if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
645        pending = &child->signal->shared_pending;
646    else
647        pending = &child->pending;
648
649    for (i = 0; i < arg.nr; ) {
650        siginfo_t info;
651        s32 off = arg.off + i;
652
653        spin_lock_irq(&child->sighand->siglock);
654        list_for_each_entry(q, &pending->list, list) {
655            if (!off--) {
656                copy_siginfo(&info, &q->info);
657                break;
658            }
659        }
660        spin_unlock_irq(&child->sighand->siglock);
661
662        if (off >= 0) /* beyond the end of the list */
663            break;
664
665#ifdef CONFIG_COMPAT
666        if (unlikely(is_compat_task())) {
667            compat_siginfo_t __user *uinfo = compat_ptr(data);
668
669            if (copy_siginfo_to_user32(uinfo, &info) ||
670                __put_user(info.si_code, &uinfo->si_code)) {
671                ret = -EFAULT;
672                break;
673            }
674
675        } else
676#endif
677        {
678            siginfo_t __user *uinfo = (siginfo_t __user *) data;
679
680            if (copy_siginfo_to_user(uinfo, &info) ||
681                __put_user(info.si_code, &uinfo->si_code)) {
682                ret = -EFAULT;
683                break;
684            }
685        }
686
687        data += sizeof(siginfo_t);
688        i++;
689
690        if (signal_pending(current))
691            break;
692
693        cond_resched();
694    }
695
696    if (i > 0)
697        return i;
698
699    return ret;
700}
701
702#ifdef PTRACE_SINGLESTEP
703#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
704#else
705#define is_singlestep(request) 0
706#endif
707
708#ifdef PTRACE_SINGLEBLOCK
709#define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
710#else
711#define is_singleblock(request) 0
712#endif
713
714#ifdef PTRACE_SYSEMU
715#define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
716#else
717#define is_sysemu_singlestep(request) 0
718#endif
719
720static int ptrace_resume(struct task_struct *child, long request,
721             unsigned long data)
722{
723    if (!valid_signal(data))
724        return -EIO;
725
726    if (request == PTRACE_SYSCALL)
727        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
728    else
729        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
730
731#ifdef TIF_SYSCALL_EMU
732    if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
733        set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
734    else
735        clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
736#endif
737
738    if (is_singleblock(request)) {
739        if (unlikely(!arch_has_block_step()))
740            return -EIO;
741        user_enable_block_step(child);
742    } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
743        if (unlikely(!arch_has_single_step()))
744            return -EIO;
745        user_enable_single_step(child);
746    } else {
747        user_disable_single_step(child);
748    }
749
750    child->exit_code = data;
751    wake_up_state(child, __TASK_TRACED);
752
753    return 0;
754}
755
756#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
757
758static const struct user_regset *
759find_regset(const struct user_regset_view *view, unsigned int type)
760{
761    const struct user_regset *regset;
762    int n;
763
764    for (n = 0; n < view->n; ++n) {
765        regset = view->regsets + n;
766        if (regset->core_note_type == type)
767            return regset;
768    }
769
770    return NULL;
771}
772
773static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
774             struct iovec *kiov)
775{
776    const struct user_regset_view *view = task_user_regset_view(task);
777    const struct user_regset *regset = find_regset(view, type);
778    int regset_no;
779
780    if (!regset || (kiov->iov_len % regset->size) != 0)
781        return -EINVAL;
782
783    regset_no = regset - view->regsets;
784    kiov->iov_len = min(kiov->iov_len,
785                (__kernel_size_t) (regset->n * regset->size));
786
787    if (req == PTRACE_GETREGSET)
788        return copy_regset_to_user(task, view, regset_no, 0,
789                       kiov->iov_len, kiov->iov_base);
790    else
791        return copy_regset_from_user(task, view, regset_no, 0,
792                         kiov->iov_len, kiov->iov_base);
793}
794
795/*
796 * This is declared in linux/regset.h and defined in machine-dependent
797 * code. We put the export here, near the primary machine-neutral use,
798 * to ensure no machine forgets it.
799 */
800EXPORT_SYMBOL_GPL(task_user_regset_view);
801#endif
802
803int ptrace_request(struct task_struct *child, long request,
804           unsigned long addr, unsigned long data)
805{
806    bool seized = child->ptrace & PT_SEIZED;
807    int ret = -EIO;
808    siginfo_t siginfo, *si;
809    void __user *datavp = (void __user *) data;
810    unsigned long __user *datalp = datavp;
811    unsigned long flags;
812
813    switch (request) {
814    case PTRACE_PEEKTEXT:
815    case PTRACE_PEEKDATA:
816        return generic_ptrace_peekdata(child, addr, data);
817    case PTRACE_POKETEXT:
818    case PTRACE_POKEDATA:
819        return generic_ptrace_pokedata(child, addr, data);
820
821#ifdef PTRACE_OLDSETOPTIONS
822    case PTRACE_OLDSETOPTIONS:
823#endif
824    case PTRACE_SETOPTIONS:
825        ret = ptrace_setoptions(child, data);
826        break;
827    case PTRACE_GETEVENTMSG:
828        ret = put_user(child->ptrace_message, datalp);
829        break;
830
831    case PTRACE_PEEKSIGINFO:
832        ret = ptrace_peek_siginfo(child, addr, data);
833        break;
834
835    case PTRACE_GETSIGINFO:
836        ret = ptrace_getsiginfo(child, &siginfo);
837        if (!ret)
838            ret = copy_siginfo_to_user(datavp, &siginfo);
839        break;
840
841    case PTRACE_SETSIGINFO:
842        if (copy_from_user(&siginfo, datavp, sizeof siginfo))
843            ret = -EFAULT;
844        else
845            ret = ptrace_setsiginfo(child, &siginfo);
846        break;
847
848    case PTRACE_GETSIGMASK:
849        if (addr != sizeof(sigset_t)) {
850            ret = -EINVAL;
851            break;
852        }
853
854        if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
855            ret = -EFAULT;
856        else
857            ret = 0;
858
859        break;
860
861    case PTRACE_SETSIGMASK: {
862        sigset_t new_set;
863
864        if (addr != sizeof(sigset_t)) {
865            ret = -EINVAL;
866            break;
867        }
868
869        if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
870            ret = -EFAULT;
871            break;
872        }
873
874        sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
875
876        /*
877         * Every thread does recalc_sigpending() after resume, so
878         * retarget_shared_pending() and recalc_sigpending() are not
879         * called here.
880         */
881        spin_lock_irq(&child->sighand->siglock);
882        child->blocked = new_set;
883        spin_unlock_irq(&child->sighand->siglock);
884
885        ret = 0;
886        break;
887    }
888
889    case PTRACE_INTERRUPT:
890        /*
891         * Stop tracee without any side-effect on signal or job
892         * control. At least one trap is guaranteed to happen
893         * after this request. If @child is already trapped, the
894         * current trap is not disturbed and another trap will
895         * happen after the current trap is ended with PTRACE_CONT.
896         *
897         * The actual trap might not be PTRACE_EVENT_STOP trap but
898         * the pending condition is cleared regardless.
899         */
900        if (unlikely(!seized || !lock_task_sighand(child, &flags)))
901            break;
902
903        /*
904         * INTERRUPT doesn't disturb existing trap sans one
905         * exception. If ptracer issued LISTEN for the current
906         * STOP, this INTERRUPT should clear LISTEN and re-trap
907         * tracee into STOP.
908         */
909        if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
910            ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
911
912        unlock_task_sighand(child, &flags);
913        ret = 0;
914        break;
915
916    case PTRACE_LISTEN:
917        /*
918         * Listen for events. Tracee must be in STOP. It's not
919         * resumed per-se but is not considered to be in TRACED by
920         * wait(2) or ptrace(2). If an async event (e.g. group
921         * stop state change) happens, tracee will enter STOP trap
922         * again. Alternatively, ptracer can issue INTERRUPT to
923         * finish listening and re-trap tracee into STOP.
924         */
925        if (unlikely(!seized || !lock_task_sighand(child, &flags)))
926            break;
927
928        si = child->last_siginfo;
929        if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
930            child->jobctl |= JOBCTL_LISTENING;
931            /*
932             * If NOTIFY is set, it means event happened between
933             * start of this trap and now. Trigger re-trap.
934             */
935            if (child->jobctl & JOBCTL_TRAP_NOTIFY)
936                ptrace_signal_wake_up(child, true);
937            ret = 0;
938        }
939        unlock_task_sighand(child, &flags);
940        break;
941
942    case PTRACE_DETACH: /* detach a process that was attached. */
943        ret = ptrace_detach(child, data);
944        break;
945
946#ifdef CONFIG_BINFMT_ELF_FDPIC
947    case PTRACE_GETFDPIC: {
948        struct mm_struct *mm = get_task_mm(child);
949        unsigned long tmp = 0;
950
951        ret = -ESRCH;
952        if (!mm)
953            break;
954
955        switch (addr) {
956        case PTRACE_GETFDPIC_EXEC:
957            tmp = mm->context.exec_fdpic_loadmap;
958            break;
959        case PTRACE_GETFDPIC_INTERP:
960            tmp = mm->context.interp_fdpic_loadmap;
961            break;
962        default:
963            break;
964        }
965        mmput(mm);
966
967        ret = put_user(tmp, datalp);
968        break;
969    }
970#endif
971
972#ifdef PTRACE_SINGLESTEP
973    case PTRACE_SINGLESTEP:
974#endif
975#ifdef PTRACE_SINGLEBLOCK
976    case PTRACE_SINGLEBLOCK:
977#endif
978#ifdef PTRACE_SYSEMU
979    case PTRACE_SYSEMU:
980    case PTRACE_SYSEMU_SINGLESTEP:
981#endif
982    case PTRACE_SYSCALL:
983    case PTRACE_CONT:
984        return ptrace_resume(child, request, data);
985
986    case PTRACE_KILL:
987        if (child->exit_state) /* already dead */
988            return 0;
989        return ptrace_resume(child, request, SIGKILL);
990
991#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
992    case PTRACE_GETREGSET:
993    case PTRACE_SETREGSET: {
994        struct iovec kiov;
995        struct iovec __user *uiov = datavp;
996
997        if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
998            return -EFAULT;
999
1000        if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1001            __get_user(kiov.iov_len, &uiov->iov_len))
1002            return -EFAULT;
1003
1004        ret = ptrace_regset(child, request, addr, &kiov);
1005        if (!ret)
1006            ret = __put_user(kiov.iov_len, &uiov->iov_len);
1007        break;
1008    }
1009#endif
1010    default:
1011        break;
1012    }
1013
1014    return ret;
1015}
1016
1017static struct task_struct *ptrace_get_task_struct(pid_t pid)
1018{
1019    struct task_struct *child;
1020
1021    rcu_read_lock();
1022    child = find_task_by_vpid(pid);
1023    if (child)
1024        get_task_struct(child);
1025    rcu_read_unlock();
1026
1027    if (!child)
1028        return ERR_PTR(-ESRCH);
1029    return child;
1030}
1031
1032#ifndef arch_ptrace_attach
1033#define arch_ptrace_attach(child) do { } while (0)
1034#endif
1035
1036SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1037        unsigned long, data)
1038{
1039    struct task_struct *child;
1040    long ret;
1041
1042    if (request == PTRACE_TRACEME) {
1043        ret = ptrace_traceme();
1044        if (!ret)
1045            arch_ptrace_attach(current);
1046        goto out;
1047    }
1048
1049    child = ptrace_get_task_struct(pid);
1050    if (IS_ERR(child)) {
1051        ret = PTR_ERR(child);
1052        goto out;
1053    }
1054
1055    if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1056        ret = ptrace_attach(child, request, addr, data);
1057        /*
1058         * Some architectures need to do book-keeping after
1059         * a ptrace attach.
1060         */
1061        if (!ret)
1062            arch_ptrace_attach(child);
1063        goto out_put_task_struct;
1064    }
1065
1066    ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1067                  request == PTRACE_INTERRUPT);
1068    if (ret < 0)
1069        goto out_put_task_struct;
1070
1071    ret = arch_ptrace(child, request, addr, data);
1072    if (ret || request != PTRACE_DETACH)
1073        ptrace_unfreeze_traced(child);
1074
1075 out_put_task_struct:
1076    put_task_struct(child);
1077 out:
1078    return ret;
1079}
1080
1081int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1082                unsigned long data)
1083{
1084    unsigned long tmp;
1085    int copied;
1086
1087    copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
1088    if (copied != sizeof(tmp))
1089        return -EIO;
1090    return put_user(tmp, (unsigned long __user *)data);
1091}
1092
1093int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1094                unsigned long data)
1095{
1096    int copied;
1097
1098    copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
1099    return (copied == sizeof(data)) ? 0 : -EIO;
1100}
1101
1102#if defined CONFIG_COMPAT
1103#include <linux/compat.h>
1104
1105int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1106              compat_ulong_t addr, compat_ulong_t data)
1107{
1108    compat_ulong_t __user *datap = compat_ptr(data);
1109    compat_ulong_t word;
1110    siginfo_t siginfo;
1111    int ret;
1112
1113    switch (request) {
1114    case PTRACE_PEEKTEXT:
1115    case PTRACE_PEEKDATA:
1116        ret = access_process_vm(child, addr, &word, sizeof(word), 0);
1117        if (ret != sizeof(word))
1118            ret = -EIO;
1119        else
1120            ret = put_user(word, datap);
1121        break;
1122
1123    case PTRACE_POKETEXT:
1124    case PTRACE_POKEDATA:
1125        ret = access_process_vm(child, addr, &data, sizeof(data), 1);
1126        ret = (ret != sizeof(data) ? -EIO : 0);
1127        break;
1128
1129    case PTRACE_GETEVENTMSG:
1130        ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1131        break;
1132
1133    case PTRACE_GETSIGINFO:
1134        ret = ptrace_getsiginfo(child, &siginfo);
1135        if (!ret)
1136            ret = copy_siginfo_to_user32(
1137                (struct compat_siginfo __user *) datap,
1138                &siginfo);
1139        break;
1140
1141    case PTRACE_SETSIGINFO:
1142        memset(&siginfo, 0, sizeof siginfo);
1143        if (copy_siginfo_from_user32(
1144                &siginfo, (struct compat_siginfo __user *) datap))
1145            ret = -EFAULT;
1146        else
1147            ret = ptrace_setsiginfo(child, &siginfo);
1148        break;
1149#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1150    case PTRACE_GETREGSET:
1151    case PTRACE_SETREGSET:
1152    {
1153        struct iovec kiov;
1154        struct compat_iovec __user *uiov =
1155            (struct compat_iovec __user *) datap;
1156        compat_uptr_t ptr;
1157        compat_size_t len;
1158
1159        if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1160            return -EFAULT;
1161
1162        if (__get_user(ptr, &uiov->iov_base) ||
1163            __get_user(len, &uiov->iov_len))
1164            return -EFAULT;
1165
1166        kiov.iov_base = compat_ptr(ptr);
1167        kiov.iov_len = len;
1168
1169        ret = ptrace_regset(child, request, addr, &kiov);
1170        if (!ret)
1171            ret = __put_user(kiov.iov_len, &uiov->iov_len);
1172        break;
1173    }
1174#endif
1175
1176    default:
1177        ret = ptrace_request(child, request, addr, data);
1178    }
1179
1180    return ret;
1181}
1182
1183COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1184               compat_long_t, addr, compat_long_t, data)
1185{
1186    struct task_struct *child;
1187    long ret;
1188
1189    if (request == PTRACE_TRACEME) {
1190        ret = ptrace_traceme();
1191        goto out;
1192    }
1193
1194    child = ptrace_get_task_struct(pid);
1195    if (IS_ERR(child)) {
1196        ret = PTR_ERR(child);
1197        goto out;
1198    }
1199
1200    if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1201        ret = ptrace_attach(child, request, addr, data);
1202        /*
1203         * Some architectures need to do book-keeping after
1204         * a ptrace attach.
1205         */
1206        if (!ret)
1207            arch_ptrace_attach(child);
1208        goto out_put_task_struct;
1209    }
1210
1211    ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1212                  request == PTRACE_INTERRUPT);
1213    if (!ret) {
1214        ret = compat_arch_ptrace(child, request, addr, data);
1215        if (ret || request != PTRACE_DETACH)
1216            ptrace_unfreeze_traced(child);
1217    }
1218
1219 out_put_task_struct:
1220    put_task_struct(child);
1221 out:
1222    return ret;
1223}
1224#endif /* CONFIG_COMPAT */
1225

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