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/module.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/audit.h>
21#include <linux/pid_namespace.h>
22#include <linux/syscalls.h>
23#include <linux/uaccess.h>
24#include <linux/regset.h>
25#include <linux/hw_breakpoint.h>
26
27
28/*
29 * ptrace a task: make the debugger its new parent and
30 * move it to the ptrace list.
31 *
32 * Must be called with the tasklist lock write-held.
33 */
34void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
35{
36    BUG_ON(!list_empty(&child->ptrace_entry));
37    list_add(&child->ptrace_entry, &new_parent->ptraced);
38    child->parent = new_parent;
39}
40
41/**
42 * __ptrace_unlink - unlink ptracee and restore its execution state
43 * @child: ptracee to be unlinked
44 *
45 * Remove @child from the ptrace list, move it back to the original parent,
46 * and restore the execution state so that it conforms to the group stop
47 * state.
48 *
49 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
50 * exiting. For PTRACE_DETACH, unless the ptracee has been killed between
51 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
52 * If the ptracer is exiting, the ptracee can be in any state.
53 *
54 * After detach, the ptracee should be in a state which conforms to the
55 * group stop. If the group is stopped or in the process of stopping, the
56 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
57 * up from TASK_TRACED.
58 *
59 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
60 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
61 * to but in the opposite direction of what happens while attaching to a
62 * stopped task. However, in this direction, the intermediate RUNNING
63 * state is not hidden even from the current ptracer and if it immediately
64 * re-attaches and performs a WNOHANG wait(2), it may fail.
65 *
66 * CONTEXT:
67 * write_lock_irq(tasklist_lock)
68 */
69void __ptrace_unlink(struct task_struct *child)
70{
71    BUG_ON(!child->ptrace);
72
73    child->ptrace = 0;
74    child->parent = child->real_parent;
75    list_del_init(&child->ptrace_entry);
76
77    spin_lock(&child->sighand->siglock);
78
79    /*
80     * Reinstate GROUP_STOP_PENDING if group stop is in effect and
81     * @child isn't dead.
82     */
83    if (!(child->flags & PF_EXITING) &&
84        (child->signal->flags & SIGNAL_STOP_STOPPED ||
85         child->signal->group_stop_count))
86        child->group_stop |= GROUP_STOP_PENDING;
87
88    /*
89     * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
90     * @child in the butt. Note that @resume should be used iff @child
91     * is in TASK_TRACED; otherwise, we might unduly disrupt
92     * TASK_KILLABLE sleeps.
93     */
94    if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
95        signal_wake_up(child, task_is_traced(child));
96
97    spin_unlock(&child->sighand->siglock);
98}
99
100/*
101 * Check that we have indeed attached to the thing..
102 */
103int ptrace_check_attach(struct task_struct *child, int kill)
104{
105    int ret = -ESRCH;
106
107    /*
108     * We take the read lock around doing both checks to close a
109     * possible race where someone else was tracing our child and
110     * detached between these two checks. After this locked check,
111     * we are sure that this is our traced child and that can only
112     * be changed by us so it's not changing right after this.
113     */
114    read_lock(&tasklist_lock);
115    if ((child->ptrace & PT_PTRACED) && child->parent == current) {
116        /*
117         * child->sighand can't be NULL, release_task()
118         * does ptrace_unlink() before __exit_signal().
119         */
120        spin_lock_irq(&child->sighand->siglock);
121        WARN_ON_ONCE(task_is_stopped(child));
122        if (task_is_traced(child) || kill)
123            ret = 0;
124        spin_unlock_irq(&child->sighand->siglock);
125    }
126    read_unlock(&tasklist_lock);
127
128    if (!ret && !kill)
129        ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
130
131    /* All systems go.. */
132    return ret;
133}
134
135int __ptrace_may_access(struct task_struct *task, unsigned int mode)
136{
137    const struct cred *cred = current_cred(), *tcred;
138
139    /* May we inspect the given task?
140     * This check is used both for attaching with ptrace
141     * and for allowing access to sensitive information in /proc.
142     *
143     * ptrace_attach denies several cases that /proc allows
144     * because setting up the necessary parent/child relationship
145     * or halting the specified task is impossible.
146     */
147    int dumpable = 0;
148    /* Don't let security modules deny introspection */
149    if (task == current)
150        return 0;
151    rcu_read_lock();
152    tcred = __task_cred(task);
153    if (cred->user->user_ns == tcred->user->user_ns &&
154        (cred->uid == tcred->euid &&
155         cred->uid == tcred->suid &&
156         cred->uid == tcred->uid &&
157         cred->gid == tcred->egid &&
158         cred->gid == tcred->sgid &&
159         cred->gid == tcred->gid))
160        goto ok;
161    if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
162        goto ok;
163    rcu_read_unlock();
164    return -EPERM;
165ok:
166    rcu_read_unlock();
167    smp_rmb();
168    if (task->mm)
169        dumpable = get_dumpable(task->mm);
170    if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
171        return -EPERM;
172
173    return security_ptrace_access_check(task, mode);
174}
175
176bool ptrace_may_access(struct task_struct *task, unsigned int mode)
177{
178    int err;
179    task_lock(task);
180    err = __ptrace_may_access(task, mode);
181    task_unlock(task);
182    return !err;
183}
184
185static int ptrace_attach(struct task_struct *task)
186{
187    bool wait_trap = false;
188    int retval;
189
190    audit_ptrace(task);
191
192    retval = -EPERM;
193    if (unlikely(task->flags & PF_KTHREAD))
194        goto out;
195    if (same_thread_group(task, current))
196        goto out;
197
198    /*
199     * Protect exec's credential calculations against our interference;
200     * interference; SUID, SGID and LSM creds get determined differently
201     * under ptrace.
202     */
203    retval = -ERESTARTNOINTR;
204    if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
205        goto out;
206
207    task_lock(task);
208    retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
209    task_unlock(task);
210    if (retval)
211        goto unlock_creds;
212
213    write_lock_irq(&tasklist_lock);
214    retval = -EPERM;
215    if (unlikely(task->exit_state))
216        goto unlock_tasklist;
217    if (task->ptrace)
218        goto unlock_tasklist;
219
220    task->ptrace = PT_PTRACED;
221    if (task_ns_capable(task, CAP_SYS_PTRACE))
222        task->ptrace |= PT_PTRACE_CAP;
223
224    __ptrace_link(task, current);
225    send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
226
227    spin_lock(&task->sighand->siglock);
228
229    /*
230     * If the task is already STOPPED, set GROUP_STOP_PENDING and
231     * TRAPPING, and kick it so that it transits to TRACED. TRAPPING
232     * will be cleared if the child completes the transition or any
233     * event which clears the group stop states happens. We'll wait
234     * for the transition to complete before returning from this
235     * function.
236     *
237     * This hides STOPPED -> RUNNING -> TRACED transition from the
238     * attaching thread but a different thread in the same group can
239     * still observe the transient RUNNING state. IOW, if another
240     * thread's WNOHANG wait(2) on the stopped tracee races against
241     * ATTACH, the wait(2) may fail due to the transient RUNNING.
242     *
243     * The following task_is_stopped() test is safe as both transitions
244     * in and out of STOPPED are protected by siglock.
245     */
246    if (task_is_stopped(task)) {
247        task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
248        signal_wake_up(task, 1);
249        wait_trap = true;
250    }
251
252    spin_unlock(&task->sighand->siglock);
253
254    retval = 0;
255unlock_tasklist:
256    write_unlock_irq(&tasklist_lock);
257unlock_creds:
258    mutex_unlock(&task->signal->cred_guard_mutex);
259out:
260    if (wait_trap)
261        wait_event(current->signal->wait_chldexit,
262               !(task->group_stop & GROUP_STOP_TRAPPING));
263    return retval;
264}
265
266/**
267 * ptrace_traceme -- helper for PTRACE_TRACEME
268 *
269 * Performs checks and sets PT_PTRACED.
270 * Should be used by all ptrace implementations for PTRACE_TRACEME.
271 */
272static int ptrace_traceme(void)
273{
274    int ret = -EPERM;
275
276    write_lock_irq(&tasklist_lock);
277    /* Are we already being traced? */
278    if (!current->ptrace) {
279        ret = security_ptrace_traceme(current->parent);
280        /*
281         * Check PF_EXITING to ensure ->real_parent has not passed
282         * exit_ptrace(). Otherwise we don't report the error but
283         * pretend ->real_parent untraces us right after return.
284         */
285        if (!ret && !(current->real_parent->flags & PF_EXITING)) {
286            current->ptrace = PT_PTRACED;
287            __ptrace_link(current, current->real_parent);
288        }
289    }
290    write_unlock_irq(&tasklist_lock);
291
292    return ret;
293}
294
295/*
296 * Called with irqs disabled, returns true if childs should reap themselves.
297 */
298static int ignoring_children(struct sighand_struct *sigh)
299{
300    int ret;
301    spin_lock(&sigh->siglock);
302    ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
303          (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
304    spin_unlock(&sigh->siglock);
305    return ret;
306}
307
308/*
309 * Called with tasklist_lock held for writing.
310 * Unlink a traced task, and clean it up if it was a traced zombie.
311 * Return true if it needs to be reaped with release_task().
312 * (We can't call release_task() here because we already hold tasklist_lock.)
313 *
314 * If it's a zombie, our attachedness prevented normal parent notification
315 * or self-reaping. Do notification now if it would have happened earlier.
316 * If it should reap itself, return true.
317 *
318 * If it's our own child, there is no notification to do. But if our normal
319 * children self-reap, then this child was prevented by ptrace and we must
320 * reap it now, in that case we must also wake up sub-threads sleeping in
321 * do_wait().
322 */
323static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
324{
325    __ptrace_unlink(p);
326
327    if (p->exit_state == EXIT_ZOMBIE) {
328        if (!task_detached(p) && thread_group_empty(p)) {
329            if (!same_thread_group(p->real_parent, tracer))
330                do_notify_parent(p, p->exit_signal);
331            else if (ignoring_children(tracer->sighand)) {
332                __wake_up_parent(p, tracer);
333                p->exit_signal = -1;
334            }
335        }
336        if (task_detached(p)) {
337            /* Mark it as in the process of being reaped. */
338            p->exit_state = EXIT_DEAD;
339            return true;
340        }
341    }
342
343    return false;
344}
345
346static int ptrace_detach(struct task_struct *child, unsigned int data)
347{
348    bool dead = false;
349
350    if (!valid_signal(data))
351        return -EIO;
352
353    /* Architecture-specific hardware disable .. */
354    ptrace_disable(child);
355    clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
356
357    write_lock_irq(&tasklist_lock);
358    /*
359     * This child can be already killed. Make sure de_thread() or
360     * our sub-thread doing do_wait() didn't do release_task() yet.
361     */
362    if (child->ptrace) {
363        child->exit_code = data;
364        dead = __ptrace_detach(current, child);
365    }
366    write_unlock_irq(&tasklist_lock);
367
368    if (unlikely(dead))
369        release_task(child);
370
371    return 0;
372}
373
374/*
375 * Detach all tasks we were using ptrace on. Called with tasklist held
376 * for writing, and returns with it held too. But note it can release
377 * and reacquire the lock.
378 */
379void exit_ptrace(struct task_struct *tracer)
380    __releases(&tasklist_lock)
381    __acquires(&tasklist_lock)
382{
383    struct task_struct *p, *n;
384    LIST_HEAD(ptrace_dead);
385
386    if (likely(list_empty(&tracer->ptraced)))
387        return;
388
389    list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
390        if (__ptrace_detach(tracer, p))
391            list_add(&p->ptrace_entry, &ptrace_dead);
392    }
393
394    write_unlock_irq(&tasklist_lock);
395    BUG_ON(!list_empty(&tracer->ptraced));
396
397    list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
398        list_del_init(&p->ptrace_entry);
399        release_task(p);
400    }
401
402    write_lock_irq(&tasklist_lock);
403}
404
405int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
406{
407    int copied = 0;
408
409    while (len > 0) {
410        char buf[128];
411        int this_len, retval;
412
413        this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
414        retval = access_process_vm(tsk, src, buf, this_len, 0);
415        if (!retval) {
416            if (copied)
417                break;
418            return -EIO;
419        }
420        if (copy_to_user(dst, buf, retval))
421            return -EFAULT;
422        copied += retval;
423        src += retval;
424        dst += retval;
425        len -= retval;
426    }
427    return copied;
428}
429
430int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
431{
432    int copied = 0;
433
434    while (len > 0) {
435        char buf[128];
436        int this_len, retval;
437
438        this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
439        if (copy_from_user(buf, src, this_len))
440            return -EFAULT;
441        retval = access_process_vm(tsk, dst, buf, this_len, 1);
442        if (!retval) {
443            if (copied)
444                break;
445            return -EIO;
446        }
447        copied += retval;
448        src += retval;
449        dst += retval;
450        len -= retval;
451    }
452    return copied;
453}
454
455static int ptrace_setoptions(struct task_struct *child, unsigned long data)
456{
457    child->ptrace &= ~PT_TRACE_MASK;
458
459    if (data & PTRACE_O_TRACESYSGOOD)
460        child->ptrace |= PT_TRACESYSGOOD;
461
462    if (data & PTRACE_O_TRACEFORK)
463        child->ptrace |= PT_TRACE_FORK;
464
465    if (data & PTRACE_O_TRACEVFORK)
466        child->ptrace |= PT_TRACE_VFORK;
467
468    if (data & PTRACE_O_TRACECLONE)
469        child->ptrace |= PT_TRACE_CLONE;
470
471    if (data & PTRACE_O_TRACEEXEC)
472        child->ptrace |= PT_TRACE_EXEC;
473
474    if (data & PTRACE_O_TRACEVFORKDONE)
475        child->ptrace |= PT_TRACE_VFORK_DONE;
476
477    if (data & PTRACE_O_TRACEEXIT)
478        child->ptrace |= PT_TRACE_EXIT;
479
480    return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
481}
482
483static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
484{
485    unsigned long flags;
486    int error = -ESRCH;
487
488    if (lock_task_sighand(child, &flags)) {
489        error = -EINVAL;
490        if (likely(child->last_siginfo != NULL)) {
491            *info = *child->last_siginfo;
492            error = 0;
493        }
494        unlock_task_sighand(child, &flags);
495    }
496    return error;
497}
498
499static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
500{
501    unsigned long flags;
502    int error = -ESRCH;
503
504    if (lock_task_sighand(child, &flags)) {
505        error = -EINVAL;
506        if (likely(child->last_siginfo != NULL)) {
507            *child->last_siginfo = *info;
508            error = 0;
509        }
510        unlock_task_sighand(child, &flags);
511    }
512    return error;
513}
514
515
516#ifdef PTRACE_SINGLESTEP
517#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
518#else
519#define is_singlestep(request) 0
520#endif
521
522#ifdef PTRACE_SINGLEBLOCK
523#define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK)
524#else
525#define is_singleblock(request) 0
526#endif
527
528#ifdef PTRACE_SYSEMU
529#define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP)
530#else
531#define is_sysemu_singlestep(request) 0
532#endif
533
534static int ptrace_resume(struct task_struct *child, long request,
535             unsigned long data)
536{
537    if (!valid_signal(data))
538        return -EIO;
539
540    if (request == PTRACE_SYSCALL)
541        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
542    else
543        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
544
545#ifdef TIF_SYSCALL_EMU
546    if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
547        set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
548    else
549        clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
550#endif
551
552    if (is_singleblock(request)) {
553        if (unlikely(!arch_has_block_step()))
554            return -EIO;
555        user_enable_block_step(child);
556    } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
557        if (unlikely(!arch_has_single_step()))
558            return -EIO;
559        user_enable_single_step(child);
560    } else {
561        user_disable_single_step(child);
562    }
563
564    child->exit_code = data;
565    wake_up_state(child, __TASK_TRACED);
566
567    return 0;
568}
569
570#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
571
572static const struct user_regset *
573find_regset(const struct user_regset_view *view, unsigned int type)
574{
575    const struct user_regset *regset;
576    int n;
577
578    for (n = 0; n < view->n; ++n) {
579        regset = view->regsets + n;
580        if (regset->core_note_type == type)
581            return regset;
582    }
583
584    return NULL;
585}
586
587static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
588             struct iovec *kiov)
589{
590    const struct user_regset_view *view = task_user_regset_view(task);
591    const struct user_regset *regset = find_regset(view, type);
592    int regset_no;
593
594    if (!regset || (kiov->iov_len % regset->size) != 0)
595        return -EINVAL;
596
597    regset_no = regset - view->regsets;
598    kiov->iov_len = min(kiov->iov_len,
599                (__kernel_size_t) (regset->n * regset->size));
600
601    if (req == PTRACE_GETREGSET)
602        return copy_regset_to_user(task, view, regset_no, 0,
603                       kiov->iov_len, kiov->iov_base);
604    else
605        return copy_regset_from_user(task, view, regset_no, 0,
606                         kiov->iov_len, kiov->iov_base);
607}
608
609#endif
610
611int ptrace_request(struct task_struct *child, long request,
612           unsigned long addr, unsigned long data)
613{
614    int ret = -EIO;
615    siginfo_t siginfo;
616    void __user *datavp = (void __user *) data;
617    unsigned long __user *datalp = datavp;
618
619    switch (request) {
620    case PTRACE_PEEKTEXT:
621    case PTRACE_PEEKDATA:
622        return generic_ptrace_peekdata(child, addr, data);
623    case PTRACE_POKETEXT:
624    case PTRACE_POKEDATA:
625        return generic_ptrace_pokedata(child, addr, data);
626
627#ifdef PTRACE_OLDSETOPTIONS
628    case PTRACE_OLDSETOPTIONS:
629#endif
630    case PTRACE_SETOPTIONS:
631        ret = ptrace_setoptions(child, data);
632        break;
633    case PTRACE_GETEVENTMSG:
634        ret = put_user(child->ptrace_message, datalp);
635        break;
636
637    case PTRACE_GETSIGINFO:
638        ret = ptrace_getsiginfo(child, &siginfo);
639        if (!ret)
640            ret = copy_siginfo_to_user(datavp, &siginfo);
641        break;
642
643    case PTRACE_SETSIGINFO:
644        if (copy_from_user(&siginfo, datavp, sizeof siginfo))
645            ret = -EFAULT;
646        else
647            ret = ptrace_setsiginfo(child, &siginfo);
648        break;
649
650    case PTRACE_DETACH: /* detach a process that was attached. */
651        ret = ptrace_detach(child, data);
652        break;
653
654#ifdef CONFIG_BINFMT_ELF_FDPIC
655    case PTRACE_GETFDPIC: {
656        struct mm_struct *mm = get_task_mm(child);
657        unsigned long tmp = 0;
658
659        ret = -ESRCH;
660        if (!mm)
661            break;
662
663        switch (addr) {
664        case PTRACE_GETFDPIC_EXEC:
665            tmp = mm->context.exec_fdpic_loadmap;
666            break;
667        case PTRACE_GETFDPIC_INTERP:
668            tmp = mm->context.interp_fdpic_loadmap;
669            break;
670        default:
671            break;
672        }
673        mmput(mm);
674
675        ret = put_user(tmp, datalp);
676        break;
677    }
678#endif
679
680#ifdef PTRACE_SINGLESTEP
681    case PTRACE_SINGLESTEP:
682#endif
683#ifdef PTRACE_SINGLEBLOCK
684    case PTRACE_SINGLEBLOCK:
685#endif
686#ifdef PTRACE_SYSEMU
687    case PTRACE_SYSEMU:
688    case PTRACE_SYSEMU_SINGLESTEP:
689#endif
690    case PTRACE_SYSCALL:
691    case PTRACE_CONT:
692        return ptrace_resume(child, request, data);
693
694    case PTRACE_KILL:
695        if (child->exit_state) /* already dead */
696            return 0;
697        return ptrace_resume(child, request, SIGKILL);
698
699#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
700    case PTRACE_GETREGSET:
701    case PTRACE_SETREGSET:
702    {
703        struct iovec kiov;
704        struct iovec __user *uiov = datavp;
705
706        if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
707            return -EFAULT;
708
709        if (__get_user(kiov.iov_base, &uiov->iov_base) ||
710            __get_user(kiov.iov_len, &uiov->iov_len))
711            return -EFAULT;
712
713        ret = ptrace_regset(child, request, addr, &kiov);
714        if (!ret)
715            ret = __put_user(kiov.iov_len, &uiov->iov_len);
716        break;
717    }
718#endif
719    default:
720        break;
721    }
722
723    return ret;
724}
725
726static struct task_struct *ptrace_get_task_struct(pid_t pid)
727{
728    struct task_struct *child;
729
730    rcu_read_lock();
731    child = find_task_by_vpid(pid);
732    if (child)
733        get_task_struct(child);
734    rcu_read_unlock();
735
736    if (!child)
737        return ERR_PTR(-ESRCH);
738    return child;
739}
740
741#ifndef arch_ptrace_attach
742#define arch_ptrace_attach(child) do { } while (0)
743#endif
744
745SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
746        unsigned long, data)
747{
748    struct task_struct *child;
749    long ret;
750
751    if (request == PTRACE_TRACEME) {
752        ret = ptrace_traceme();
753        if (!ret)
754            arch_ptrace_attach(current);
755        goto out;
756    }
757
758    child = ptrace_get_task_struct(pid);
759    if (IS_ERR(child)) {
760        ret = PTR_ERR(child);
761        goto out;
762    }
763
764    if (request == PTRACE_ATTACH) {
765        ret = ptrace_attach(child);
766        /*
767         * Some architectures need to do book-keeping after
768         * a ptrace attach.
769         */
770        if (!ret)
771            arch_ptrace_attach(child);
772        goto out_put_task_struct;
773    }
774
775    ret = ptrace_check_attach(child, request == PTRACE_KILL);
776    if (ret < 0)
777        goto out_put_task_struct;
778
779    ret = arch_ptrace(child, request, addr, data);
780
781 out_put_task_struct:
782    put_task_struct(child);
783 out:
784    return ret;
785}
786
787int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
788                unsigned long data)
789{
790    unsigned long tmp;
791    int copied;
792
793    copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
794    if (copied != sizeof(tmp))
795        return -EIO;
796    return put_user(tmp, (unsigned long __user *)data);
797}
798
799int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
800                unsigned long data)
801{
802    int copied;
803
804    copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
805    return (copied == sizeof(data)) ? 0 : -EIO;
806}
807
808#if defined CONFIG_COMPAT
809#include <linux/compat.h>
810
811int compat_ptrace_request(struct task_struct *child, compat_long_t request,
812              compat_ulong_t addr, compat_ulong_t data)
813{
814    compat_ulong_t __user *datap = compat_ptr(data);
815    compat_ulong_t word;
816    siginfo_t siginfo;
817    int ret;
818
819    switch (request) {
820    case PTRACE_PEEKTEXT:
821    case PTRACE_PEEKDATA:
822        ret = access_process_vm(child, addr, &word, sizeof(word), 0);
823        if (ret != sizeof(word))
824            ret = -EIO;
825        else
826            ret = put_user(word, datap);
827        break;
828
829    case PTRACE_POKETEXT:
830    case PTRACE_POKEDATA:
831        ret = access_process_vm(child, addr, &data, sizeof(data), 1);
832        ret = (ret != sizeof(data) ? -EIO : 0);
833        break;
834
835    case PTRACE_GETEVENTMSG:
836        ret = put_user((compat_ulong_t) child->ptrace_message, datap);
837        break;
838
839    case PTRACE_GETSIGINFO:
840        ret = ptrace_getsiginfo(child, &siginfo);
841        if (!ret)
842            ret = copy_siginfo_to_user32(
843                (struct compat_siginfo __user *) datap,
844                &siginfo);
845        break;
846
847    case PTRACE_SETSIGINFO:
848        memset(&siginfo, 0, sizeof siginfo);
849        if (copy_siginfo_from_user32(
850                &siginfo, (struct compat_siginfo __user *) datap))
851            ret = -EFAULT;
852        else
853            ret = ptrace_setsiginfo(child, &siginfo);
854        break;
855#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
856    case PTRACE_GETREGSET:
857    case PTRACE_SETREGSET:
858    {
859        struct iovec kiov;
860        struct compat_iovec __user *uiov =
861            (struct compat_iovec __user *) datap;
862        compat_uptr_t ptr;
863        compat_size_t len;
864
865        if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
866            return -EFAULT;
867
868        if (__get_user(ptr, &uiov->iov_base) ||
869            __get_user(len, &uiov->iov_len))
870            return -EFAULT;
871
872        kiov.iov_base = compat_ptr(ptr);
873        kiov.iov_len = len;
874
875        ret = ptrace_regset(child, request, addr, &kiov);
876        if (!ret)
877            ret = __put_user(kiov.iov_len, &uiov->iov_len);
878        break;
879    }
880#endif
881
882    default:
883        ret = ptrace_request(child, request, addr, data);
884    }
885
886    return ret;
887}
888
889asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
890                  compat_long_t addr, compat_long_t data)
891{
892    struct task_struct *child;
893    long ret;
894
895    if (request == PTRACE_TRACEME) {
896        ret = ptrace_traceme();
897        goto out;
898    }
899
900    child = ptrace_get_task_struct(pid);
901    if (IS_ERR(child)) {
902        ret = PTR_ERR(child);
903        goto out;
904    }
905
906    if (request == PTRACE_ATTACH) {
907        ret = ptrace_attach(child);
908        /*
909         * Some architectures need to do book-keeping after
910         * a ptrace attach.
911         */
912        if (!ret)
913            arch_ptrace_attach(child);
914        goto out_put_task_struct;
915    }
916
917    ret = ptrace_check_attach(child, request == PTRACE_KILL);
918    if (!ret)
919        ret = compat_arch_ptrace(child, request, addr, data);
920
921 out_put_task_struct:
922    put_task_struct(child);
923 out:
924    return ret;
925}
926#endif /* CONFIG_COMPAT */
927
928#ifdef CONFIG_HAVE_HW_BREAKPOINT
929int ptrace_get_breakpoints(struct task_struct *tsk)
930{
931    if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
932        return 0;
933
934    return -1;
935}
936
937void ptrace_put_breakpoints(struct task_struct *tsk)
938{
939    if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
940        flush_ptrace_hw_breakpoint(tsk);
941}
942#endif /* CONFIG_HAVE_HW_BREAKPOINT */
943

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