linux/kernel/ptrace.c
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   1/*
   2 * linux/kernel/ptrace.c
   3 *
   4 * (C) Copyright 1999 Linus Torvalds
   5 *
   6 * Common interfaces for "ptrace()" which we do not want
   7 * to continually duplicate across every architecture.
   8 */
   9
  10#include <linux/capability.h>
  11#include <linux/export.h>
  12#include <linux/sched.h>
  13#include <linux/errno.h>
  14#include <linux/mm.h>
  15#include <linux/highmem.h>
  16#include <linux/pagemap.h>
  17#include <linux/ptrace.h>
  18#include <linux/security.h>
  19#include <linux/signal.h>
  20#include <linux/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#include <linux/cn_proc.h>
  27
  28
  29static int ptrace_trapping_sleep_fn(void *flags)
  30{
  31        schedule();
  32        return 0;
  33}
  34
  35/*
  36 * ptrace a task: make the debugger its new parent and
  37 * move it to the ptrace list.
  38 *
  39 * Must be called with the tasklist lock write-held.
  40 */
  41void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  42{
  43        BUG_ON(!list_empty(&child->ptrace_entry));
  44        list_add(&child->ptrace_entry, &new_parent->ptraced);
  45        child->parent = new_parent;
  46}
  47
  48/**
  49 * __ptrace_unlink - unlink ptracee and restore its execution state
  50 * @child: ptracee to be unlinked
  51 *
  52 * Remove @child from the ptrace list, move it back to the original parent,
  53 * and restore the execution state so that it conforms to the group stop
  54 * state.
  55 *
  56 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  57 * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  58 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  59 * If the ptracer is exiting, the ptracee can be in any state.
  60 *
  61 * After detach, the ptracee should be in a state which conforms to the
  62 * group stop.  If the group is stopped or in the process of stopping, the
  63 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  64 * up from TASK_TRACED.
  65 *
  66 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  67 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  68 * to but in the opposite direction of what happens while attaching to a
  69 * stopped task.  However, in this direction, the intermediate RUNNING
  70 * state is not hidden even from the current ptracer and if it immediately
  71 * re-attaches and performs a WNOHANG wait(2), it may fail.
  72 *
  73 * CONTEXT:
  74 * write_lock_irq(tasklist_lock)
  75 */
  76void __ptrace_unlink(struct task_struct *child)
  77{
  78        BUG_ON(!child->ptrace);
  79
  80        child->ptrace = 0;
  81        child->parent = child->real_parent;
  82        list_del_init(&child->ptrace_entry);
  83
  84        spin_lock(&child->sighand->siglock);
  85
  86        /*
  87         * Clear all pending traps and TRAPPING.  TRAPPING should be
  88         * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
  89         */
  90        task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
  91        task_clear_jobctl_trapping(child);
  92
  93        /*
  94         * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
  95         * @child isn't dead.
  96         */
  97        if (!(child->flags & PF_EXITING) &&
  98            (child->signal->flags & SIGNAL_STOP_STOPPED ||
  99             child->signal->group_stop_count)) {
 100                child->jobctl |= JOBCTL_STOP_PENDING;
 101
 102                /*
 103                 * This is only possible if this thread was cloned by the
 104                 * traced task running in the stopped group, set the signal
 105                 * for the future reports.
 106                 * FIXME: we should change ptrace_init_task() to handle this
 107                 * case.
 108                 */
 109                if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
 110                        child->jobctl |= SIGSTOP;
 111        }
 112
 113        /*
 114         * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
 115         * @child in the butt.  Note that @resume should be used iff @child
 116         * is in TASK_TRACED; otherwise, we might unduly disrupt
 117         * TASK_KILLABLE sleeps.
 118         */
 119        if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
 120                signal_wake_up(child, task_is_traced(child));
 121
 122        spin_unlock(&child->sighand->siglock);
 123}
 124
 125/**
 126 * ptrace_check_attach - check whether ptracee is ready for ptrace operation
 127 * @child: ptracee to check for
 128 * @ignore_state: don't check whether @child is currently %TASK_TRACED
 129 *
 130 * Check whether @child is being ptraced by %current and ready for further
 131 * ptrace operations.  If @ignore_state is %false, @child also should be in
 132 * %TASK_TRACED state and on return the child is guaranteed to be traced
 133 * and not executing.  If @ignore_state is %true, @child can be in any
 134 * state.
 135 *
 136 * CONTEXT:
 137 * Grabs and releases tasklist_lock and @child->sighand->siglock.
 138 *
 139 * RETURNS:
 140 * 0 on success, -ESRCH if %child is not ready.
 141 */
 142int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 143{
 144        int ret = -ESRCH;
 145
 146        /*
 147         * We take the read lock around doing both checks to close a
 148         * possible race where someone else was tracing our child and
 149         * detached between these two checks.  After this locked check,
 150         * we are sure that this is our traced child and that can only
 151         * be changed by us so it's not changing right after this.
 152         */
 153        read_lock(&tasklist_lock);
 154        if ((child->ptrace & PT_PTRACED) && child->parent == current) {
 155                /*
 156                 * child->sighand can't be NULL, release_task()
 157                 * does ptrace_unlink() before __exit_signal().
 158                 */
 159                spin_lock_irq(&child->sighand->siglock);
 160                WARN_ON_ONCE(task_is_stopped(child));
 161                if (ignore_state || (task_is_traced(child) &&
 162                                     !(child->jobctl & JOBCTL_LISTENING)))
 163                        ret = 0;
 164                spin_unlock_irq(&child->sighand->siglock);
 165        }
 166        read_unlock(&tasklist_lock);
 167
 168        if (!ret && !ignore_state)
 169                ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 170
 171        /* All systems go.. */
 172        return ret;
 173}
 174
 175static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 176{
 177        if (mode & PTRACE_MODE_NOAUDIT)
 178                return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
 179        else
 180                return has_ns_capability(current, ns, CAP_SYS_PTRACE);
 181}
 182
 183int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 184{
 185        const struct cred *cred = current_cred(), *tcred;
 186
 187        /* May we inspect the given task?
 188         * This check is used both for attaching with ptrace
 189         * and for allowing access to sensitive information in /proc.
 190         *
 191         * ptrace_attach denies several cases that /proc allows
 192         * because setting up the necessary parent/child relationship
 193         * or halting the specified task is impossible.
 194         */
 195        int dumpable = 0;
 196        /* Don't let security modules deny introspection */
 197        if (task == current)
 198                return 0;
 199        rcu_read_lock();
 200        tcred = __task_cred(task);
 201        if (uid_eq(cred->uid, tcred->euid) &&
 202            uid_eq(cred->uid, tcred->suid) &&
 203            uid_eq(cred->uid, tcred->uid)  &&
 204            gid_eq(cred->gid, tcred->egid) &&
 205            gid_eq(cred->gid, tcred->sgid) &&
 206            gid_eq(cred->gid, tcred->gid))
 207                goto ok;
 208        if (ptrace_has_cap(tcred->user_ns, mode))
 209                goto ok;
 210        rcu_read_unlock();
 211        return -EPERM;
 212ok:
 213        rcu_read_unlock();
 214        smp_rmb();
 215        if (task->mm)
 216                dumpable = get_dumpable(task->mm);
 217        if (!dumpable  && !ptrace_has_cap(task_user_ns(task), mode))
 218                return -EPERM;
 219
 220        return security_ptrace_access_check(task, mode);
 221}
 222
 223bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 224{
 225        int err;
 226        task_lock(task);
 227        err = __ptrace_may_access(task, mode);
 228        task_unlock(task);
 229        return !err;
 230}
 231
 232static int ptrace_attach(struct task_struct *task, long request,
 233                         unsigned long addr,
 234                         unsigned long flags)
 235{
 236        bool seize = (request == PTRACE_SEIZE);
 237        int retval;
 238
 239        retval = -EIO;
 240        if (seize) {
 241                if (addr != 0)
 242                        goto out;
 243                if (flags & ~(unsigned long)PTRACE_O_MASK)
 244                        goto out;
 245                flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
 246        } else {
 247                flags = PT_PTRACED;
 248        }
 249
 250        audit_ptrace(task);
 251
 252        retval = -EPERM;
 253        if (unlikely(task->flags & PF_KTHREAD))
 254                goto out;
 255        if (same_thread_group(task, current))
 256                goto out;
 257
 258        /*
 259         * Protect exec's credential calculations against our interference;
 260         * SUID, SGID and LSM creds get determined differently
 261         * under ptrace.
 262         */
 263        retval = -ERESTARTNOINTR;
 264        if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 265                goto out;
 266
 267        task_lock(task);
 268        retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 269        task_unlock(task);
 270        if (retval)
 271                goto unlock_creds;
 272
 273        write_lock_irq(&tasklist_lock);
 274        retval = -EPERM;
 275        if (unlikely(task->exit_state))
 276                goto unlock_tasklist;
 277        if (task->ptrace)
 278                goto unlock_tasklist;
 279
 280        if (seize)
 281                flags |= PT_SEIZED;
 282        if (ns_capable(task_user_ns(task), CAP_SYS_PTRACE))
 283                flags |= PT_PTRACE_CAP;
 284        task->ptrace = flags;
 285
 286        __ptrace_link(task, current);
 287
 288        /* SEIZE doesn't trap tracee on attach */
 289        if (!seize)
 290                send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 291
 292        spin_lock(&task->sighand->siglock);
 293
 294        /*
 295         * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
 296         * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 297         * will be cleared if the child completes the transition or any
 298         * event which clears the group stop states happens.  We'll wait
 299         * for the transition to complete before returning from this
 300         * function.
 301         *
 302         * This hides STOPPED -> RUNNING -> TRACED transition from the
 303         * attaching thread but a different thread in the same group can
 304         * still observe the transient RUNNING state.  IOW, if another
 305         * thread's WNOHANG wait(2) on the stopped tracee races against
 306         * ATTACH, the wait(2) may fail due to the transient RUNNING.
 307         *
 308         * The following task_is_stopped() test is safe as both transitions
 309         * in and out of STOPPED are protected by siglock.
 310         */
 311        if (task_is_stopped(task) &&
 312            task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
 313                signal_wake_up(task, 1);
 314
 315        spin_unlock(&task->sighand->siglock);
 316
 317        retval = 0;
 318unlock_tasklist:
 319        write_unlock_irq(&tasklist_lock);
 320unlock_creds:
 321        mutex_unlock(&task->signal->cred_guard_mutex);
 322out:
 323        if (!retval) {
 324                wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
 325                            ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
 326                proc_ptrace_connector(task, PTRACE_ATTACH);
 327        }
 328
 329        return retval;
 330}
 331
 332/**
 333 * ptrace_traceme  --  helper for PTRACE_TRACEME
 334 *
 335 * Performs checks and sets PT_PTRACED.
 336 * Should be used by all ptrace implementations for PTRACE_TRACEME.
 337 */
 338static int ptrace_traceme(void)
 339{
 340        int ret = -EPERM;
 341
 342        write_lock_irq(&tasklist_lock);
 343        /* Are we already being traced? */
 344        if (!current->ptrace) {
 345                ret = security_ptrace_traceme(current->parent);
 346                /*
 347                 * Check PF_EXITING to ensure ->real_parent has not passed
 348                 * exit_ptrace(). Otherwise we don't report the error but
 349                 * pretend ->real_parent untraces us right after return.
 350                 */
 351                if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 352                        current->ptrace = PT_PTRACED;
 353                        __ptrace_link(current, current->real_parent);
 354                }
 355        }
 356        write_unlock_irq(&tasklist_lock);
 357
 358        return ret;
 359}
 360
 361/*
 362 * Called with irqs disabled, returns true if childs should reap themselves.
 363 */
 364static int ignoring_children(struct sighand_struct *sigh)
 365{
 366        int ret;
 367        spin_lock(&sigh->siglock);
 368        ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 369              (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 370        spin_unlock(&sigh->siglock);
 371        return ret;
 372}
 373
 374/*
 375 * Called with tasklist_lock held for writing.
 376 * Unlink a traced task, and clean it up if it was a traced zombie.
 377 * Return true if it needs to be reaped with release_task().
 378 * (We can't call release_task() here because we already hold tasklist_lock.)
 379 *
 380 * If it's a zombie, our attachedness prevented normal parent notification
 381 * or self-reaping.  Do notification now if it would have happened earlier.
 382 * If it should reap itself, return true.
 383 *
 384 * If it's our own child, there is no notification to do. But if our normal
 385 * children self-reap, then this child was prevented by ptrace and we must
 386 * reap it now, in that case we must also wake up sub-threads sleeping in
 387 * do_wait().
 388 */
 389static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 390{
 391        bool dead;
 392
 393        __ptrace_unlink(p);
 394
 395        if (p->exit_state != EXIT_ZOMBIE)
 396                return false;
 397
 398        dead = !thread_group_leader(p);
 399
 400        if (!dead && thread_group_empty(p)) {
 401                if (!same_thread_group(p->real_parent, tracer))
 402                        dead = do_notify_parent(p, p->exit_signal);
 403                else if (ignoring_children(tracer->sighand)) {
 404                        __wake_up_parent(p, tracer);
 405                        dead = true;
 406                }
 407        }
 408        /* Mark it as in the process of being reaped. */
 409        if (dead)
 410                p->exit_state = EXIT_DEAD;
 411        return dead;
 412}
 413
 414static int ptrace_detach(struct task_struct *child, unsigned int data)
 415{
 416        bool dead = false;
 417
 418        if (!valid_signal(data))
 419                return -EIO;
 420
 421        /* Architecture-specific hardware disable .. */
 422        ptrace_disable(child);
 423        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 424
 425        write_lock_irq(&tasklist_lock);
 426        /*
 427         * This child can be already killed. Make sure de_thread() or
 428         * our sub-thread doing do_wait() didn't do release_task() yet.
 429         */
 430        if (child->ptrace) {
 431                child->exit_code = data;
 432                dead = __ptrace_detach(current, child);
 433        }
 434        write_unlock_irq(&tasklist_lock);
 435
 436        proc_ptrace_connector(child, PTRACE_DETACH);
 437        if (unlikely(dead))
 438                release_task(child);
 439
 440        return 0;
 441}
 442
 443/*
 444 * Detach all tasks we were using ptrace on. Called with tasklist held
 445 * for writing, and returns with it held too. But note it can release
 446 * and reacquire the lock.
 447 */
 448void exit_ptrace(struct task_struct *tracer)
 449        __releases(&tasklist_lock)
 450        __acquires(&tasklist_lock)
 451{
 452        struct task_struct *p, *n;
 453        LIST_HEAD(ptrace_dead);
 454
 455        if (likely(list_empty(&tracer->ptraced)))
 456                return;
 457
 458        list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 459                if (__ptrace_detach(tracer, p))
 460                        list_add(&p->ptrace_entry, &ptrace_dead);
 461        }
 462
 463        write_unlock_irq(&tasklist_lock);
 464        BUG_ON(!list_empty(&tracer->ptraced));
 465
 466        list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 467                list_del_init(&p->ptrace_entry);
 468                release_task(p);
 469        }
 470
 471        write_lock_irq(&tasklist_lock);
 472}
 473
 474int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 475{
 476        int copied = 0;
 477
 478        while (len > 0) {
 479                char buf[128];
 480                int this_len, retval;
 481
 482                this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 483                retval = access_process_vm(tsk, src, buf, this_len, 0);
 484                if (!retval) {
 485                        if (copied)
 486                                break;
 487                        return -EIO;
 488                }
 489                if (copy_to_user(dst, buf, retval))
 490                        return -EFAULT;
 491                copied += retval;
 492                src += retval;
 493                dst += retval;
 494                len -= retval;
 495        }
 496        return copied;
 497}
 498
 499int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 500{
 501        int copied = 0;
 502
 503        while (len > 0) {
 504                char buf[128];
 505                int this_len, retval;
 506
 507                this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 508                if (copy_from_user(buf, src, this_len))
 509                        return -EFAULT;
 510                retval = access_process_vm(tsk, dst, buf, this_len, 1);
 511                if (!retval) {
 512                        if (copied)
 513                                break;
 514                        return -EIO;
 515                }
 516                copied += retval;
 517                src += retval;
 518                dst += retval;
 519                len -= retval;
 520        }
 521        return copied;
 522}
 523
 524static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 525{
 526        unsigned flags;
 527
 528        if (data & ~(unsigned long)PTRACE_O_MASK)
 529                return -EINVAL;
 530
 531        /* Avoid intermediate state when all opts are cleared */
 532        flags = child->ptrace;
 533        flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
 534        flags |= (data << PT_OPT_FLAG_SHIFT);
 535        child->ptrace = flags;
 536
 537        return 0;
 538}
 539
 540static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 541{
 542        unsigned long flags;
 543        int error = -ESRCH;
 544
 545        if (lock_task_sighand(child, &flags)) {
 546                error = -EINVAL;
 547                if (likely(child->last_siginfo != NULL)) {
 548                        *info = *child->last_siginfo;
 549                        error = 0;
 550                }
 551                unlock_task_sighand(child, &flags);
 552        }
 553        return error;
 554}
 555
 556static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 557{
 558        unsigned long flags;
 559        int error = -ESRCH;
 560
 561        if (lock_task_sighand(child, &flags)) {
 562                error = -EINVAL;
 563                if (likely(child->last_siginfo != NULL)) {
 564                        *child->last_siginfo = *info;
 565                        error = 0;
 566                }
 567                unlock_task_sighand(child, &flags);
 568        }
 569        return error;
 570}
 571
 572
 573#ifdef PTRACE_SINGLESTEP
 574#define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 575#else
 576#define is_singlestep(request)          0
 577#endif
 578
 579#ifdef PTRACE_SINGLEBLOCK
 580#define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 581#else
 582#define is_singleblock(request)         0
 583#endif
 584
 585#ifdef PTRACE_SYSEMU
 586#define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 587#else
 588#define is_sysemu_singlestep(request)   0
 589#endif
 590
 591static int ptrace_resume(struct task_struct *child, long request,
 592                         unsigned long data)
 593{
 594        if (!valid_signal(data))
 595                return -EIO;
 596
 597        if (request == PTRACE_SYSCALL)
 598                set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 599        else
 600                clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 601
 602#ifdef TIF_SYSCALL_EMU
 603        if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 604                set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 605        else
 606                clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 607#endif
 608
 609        if (is_singleblock(request)) {
 610                if (unlikely(!arch_has_block_step()))
 611                        return -EIO;
 612                user_enable_block_step(child);
 613        } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 614                if (unlikely(!arch_has_single_step()))
 615                        return -EIO;
 616                user_enable_single_step(child);
 617        } else {
 618                user_disable_single_step(child);
 619        }
 620
 621        child->exit_code = data;
 622        wake_up_state(child, __TASK_TRACED);
 623
 624        return 0;
 625}
 626
 627#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 628
 629static const struct user_regset *
 630find_regset(const struct user_regset_view *view, unsigned int type)
 631{
 632        const struct user_regset *regset;
 633        int n;
 634
 635        for (n = 0; n < view->n; ++n) {
 636                regset = view->regsets + n;
 637                if (regset->core_note_type == type)
 638                        return regset;
 639        }
 640
 641        return NULL;
 642}
 643
 644static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 645                         struct iovec *kiov)
 646{
 647        const struct user_regset_view *view = task_user_regset_view(task);
 648        const struct user_regset *regset = find_regset(view, type);
 649        int regset_no;
 650
 651        if (!regset || (kiov->iov_len % regset->size) != 0)
 652                return -EINVAL;
 653
 654        regset_no = regset - view->regsets;
 655        kiov->iov_len = min(kiov->iov_len,
 656                            (__kernel_size_t) (regset->n * regset->size));
 657
 658        if (req == PTRACE_GETREGSET)
 659                return copy_regset_to_user(task, view, regset_no, 0,
 660                                           kiov->iov_len, kiov->iov_base);
 661        else
 662                return copy_regset_from_user(task, view, regset_no, 0,
 663                                             kiov->iov_len, kiov->iov_base);
 664}
 665
 666#endif
 667
 668int ptrace_request(struct task_struct *child, long request,
 669                   unsigned long addr, unsigned long data)
 670{
 671        bool seized = child->ptrace & PT_SEIZED;
 672        int ret = -EIO;
 673        siginfo_t siginfo, *si;
 674        void __user *datavp = (void __user *) data;
 675        unsigned long __user *datalp = datavp;
 676        unsigned long flags;
 677
 678        switch (request) {
 679        case PTRACE_PEEKTEXT:
 680        case PTRACE_PEEKDATA:
 681                return generic_ptrace_peekdata(child, addr, data);
 682        case PTRACE_POKETEXT:
 683        case PTRACE_POKEDATA:
 684                return generic_ptrace_pokedata(child, addr, data);
 685
 686#ifdef PTRACE_OLDSETOPTIONS
 687        case PTRACE_OLDSETOPTIONS:
 688#endif
 689        case PTRACE_SETOPTIONS:
 690                ret = ptrace_setoptions(child, data);
 691                break;
 692        case PTRACE_GETEVENTMSG:
 693                ret = put_user(child->ptrace_message, datalp);
 694                break;
 695
 696        case PTRACE_GETSIGINFO:
 697                ret = ptrace_getsiginfo(child, &siginfo);
 698                if (!ret)
 699                        ret = copy_siginfo_to_user(datavp, &siginfo);
 700                break;
 701
 702        case PTRACE_SETSIGINFO:
 703                if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 704                        ret = -EFAULT;
 705                else
 706                        ret = ptrace_setsiginfo(child, &siginfo);
 707                break;
 708
 709        case PTRACE_INTERRUPT:
 710                /*
 711                 * Stop tracee without any side-effect on signal or job
 712                 * control.  At least one trap is guaranteed to happen
 713                 * after this request.  If @child is already trapped, the
 714                 * current trap is not disturbed and another trap will
 715                 * happen after the current trap is ended with PTRACE_CONT.
 716                 *
 717                 * The actual trap might not be PTRACE_EVENT_STOP trap but
 718                 * the pending condition is cleared regardless.
 719                 */
 720                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 721                        break;
 722
 723                /*
 724                 * INTERRUPT doesn't disturb existing trap sans one
 725                 * exception.  If ptracer issued LISTEN for the current
 726                 * STOP, this INTERRUPT should clear LISTEN and re-trap
 727                 * tracee into STOP.
 728                 */
 729                if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
 730                        signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
 731
 732                unlock_task_sighand(child, &flags);
 733                ret = 0;
 734                break;
 735
 736        case PTRACE_LISTEN:
 737                /*
 738                 * Listen for events.  Tracee must be in STOP.  It's not
 739                 * resumed per-se but is not considered to be in TRACED by
 740                 * wait(2) or ptrace(2).  If an async event (e.g. group
 741                 * stop state change) happens, tracee will enter STOP trap
 742                 * again.  Alternatively, ptracer can issue INTERRUPT to
 743                 * finish listening and re-trap tracee into STOP.
 744                 */
 745                if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 746                        break;
 747
 748                si = child->last_siginfo;
 749                if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
 750                        child->jobctl |= JOBCTL_LISTENING;
 751                        /*
 752                         * If NOTIFY is set, it means event happened between
 753                         * start of this trap and now.  Trigger re-trap.
 754                         */
 755                        if (child->jobctl & JOBCTL_TRAP_NOTIFY)
 756                                signal_wake_up(child, true);
 757                        ret = 0;
 758                }
 759                unlock_task_sighand(child, &flags);
 760                break;
 761
 762        case PTRACE_DETACH:      /* detach a process that was attached. */
 763                ret = ptrace_detach(child, data);
 764                break;
 765
 766#ifdef CONFIG_BINFMT_ELF_FDPIC
 767        case PTRACE_GETFDPIC: {
 768                struct mm_struct *mm = get_task_mm(child);
 769                unsigned long tmp = 0;
 770
 771                ret = -ESRCH;
 772                if (!mm)
 773                        break;
 774
 775                switch (addr) {
 776                case PTRACE_GETFDPIC_EXEC:
 777                        tmp = mm->context.exec_fdpic_loadmap;
 778                        break;
 779                case PTRACE_GETFDPIC_INTERP:
 780                        tmp = mm->context.interp_fdpic_loadmap;
 781                        break;
 782                default:
 783                        break;
 784                }
 785                mmput(mm);
 786
 787                ret = put_user(tmp, datalp);
 788                break;
 789        }
 790#endif
 791
 792#ifdef PTRACE_SINGLESTEP
 793        case PTRACE_SINGLESTEP:
 794#endif
 795#ifdef PTRACE_SINGLEBLOCK
 796        case PTRACE_SINGLEBLOCK:
 797#endif
 798#ifdef PTRACE_SYSEMU
 799        case PTRACE_SYSEMU:
 800        case PTRACE_SYSEMU_SINGLESTEP:
 801#endif
 802        case PTRACE_SYSCALL:
 803        case PTRACE_CONT:
 804                return ptrace_resume(child, request, data);
 805
 806        case PTRACE_KILL:
 807                if (child->exit_state)  /* already dead */
 808                        return 0;
 809                return ptrace_resume(child, request, SIGKILL);
 810
 811#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 812        case PTRACE_GETREGSET:
 813        case PTRACE_SETREGSET:
 814        {
 815                struct iovec kiov;
 816                struct iovec __user *uiov = datavp;
 817
 818                if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 819                        return -EFAULT;
 820
 821                if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 822                    __get_user(kiov.iov_len, &uiov->iov_len))
 823                        return -EFAULT;
 824
 825                ret = ptrace_regset(child, request, addr, &kiov);
 826                if (!ret)
 827                        ret = __put_user(kiov.iov_len, &uiov->iov_len);
 828                break;
 829        }
 830#endif
 831        default:
 832                break;
 833        }
 834
 835        return ret;
 836}
 837
 838static struct task_struct *ptrace_get_task_struct(pid_t pid)
 839{
 840        struct task_struct *child;
 841
 842        rcu_read_lock();
 843        child = find_task_by_vpid(pid);
 844        if (child)
 845                get_task_struct(child);
 846        rcu_read_unlock();
 847
 848        if (!child)
 849                return ERR_PTR(-ESRCH);
 850        return child;
 851}
 852
 853#ifndef arch_ptrace_attach
 854#define arch_ptrace_attach(child)       do { } while (0)
 855#endif
 856
 857SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 858                unsigned long, data)
 859{
 860        struct task_struct *child;
 861        long ret;
 862
 863        if (request == PTRACE_TRACEME) {
 864                ret = ptrace_traceme();
 865                if (!ret)
 866                        arch_ptrace_attach(current);
 867                goto out;
 868        }
 869
 870        child = ptrace_get_task_struct(pid);
 871        if (IS_ERR(child)) {
 872                ret = PTR_ERR(child);
 873                goto out;
 874        }
 875
 876        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 877                ret = ptrace_attach(child, request, addr, data);
 878                /*
 879                 * Some architectures need to do book-keeping after
 880                 * a ptrace attach.
 881                 */
 882                if (!ret)
 883                        arch_ptrace_attach(child);
 884                goto out_put_task_struct;
 885        }
 886
 887        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
 888                                  request == PTRACE_INTERRUPT);
 889        if (ret < 0)
 890                goto out_put_task_struct;
 891
 892        ret = arch_ptrace(child, request, addr, data);
 893
 894 out_put_task_struct:
 895        put_task_struct(child);
 896 out:
 897        return ret;
 898}
 899
 900int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 901                            unsigned long data)
 902{
 903        unsigned long tmp;
 904        int copied;
 905
 906        copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 907        if (copied != sizeof(tmp))
 908                return -EIO;
 909        return put_user(tmp, (unsigned long __user *)data);
 910}
 911
 912int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 913                            unsigned long data)
 914{
 915        int copied;
 916
 917        copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 918        return (copied == sizeof(data)) ? 0 : -EIO;
 919}
 920
 921#if defined CONFIG_COMPAT
 922#include <linux/compat.h>
 923
 924int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 925                          compat_ulong_t addr, compat_ulong_t data)
 926{
 927        compat_ulong_t __user *datap = compat_ptr(data);
 928        compat_ulong_t word;
 929        siginfo_t siginfo;
 930        int ret;
 931
 932        switch (request) {
 933        case PTRACE_PEEKTEXT:
 934        case PTRACE_PEEKDATA:
 935                ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 936                if (ret != sizeof(word))
 937                        ret = -EIO;
 938                else
 939                        ret = put_user(word, datap);
 940                break;
 941
 942        case PTRACE_POKETEXT:
 943        case PTRACE_POKEDATA:
 944                ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 945                ret = (ret != sizeof(data) ? -EIO : 0);
 946                break;
 947
 948        case PTRACE_GETEVENTMSG:
 949                ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 950                break;
 951
 952        case PTRACE_GETSIGINFO:
 953                ret = ptrace_getsiginfo(child, &siginfo);
 954                if (!ret)
 955                        ret = copy_siginfo_to_user32(
 956                                (struct compat_siginfo __user *) datap,
 957                                &siginfo);
 958                break;
 959
 960        case PTRACE_SETSIGINFO:
 961                memset(&siginfo, 0, sizeof siginfo);
 962                if (copy_siginfo_from_user32(
 963                            &siginfo, (struct compat_siginfo __user *) datap))
 964                        ret = -EFAULT;
 965                else
 966                        ret = ptrace_setsiginfo(child, &siginfo);
 967                break;
 968#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 969        case PTRACE_GETREGSET:
 970        case PTRACE_SETREGSET:
 971        {
 972                struct iovec kiov;
 973                struct compat_iovec __user *uiov =
 974                        (struct compat_iovec __user *) datap;
 975                compat_uptr_t ptr;
 976                compat_size_t len;
 977
 978                if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 979                        return -EFAULT;
 980
 981                if (__get_user(ptr, &uiov->iov_base) ||
 982                    __get_user(len, &uiov->iov_len))
 983                        return -EFAULT;
 984
 985                kiov.iov_base = compat_ptr(ptr);
 986                kiov.iov_len = len;
 987
 988                ret = ptrace_regset(child, request, addr, &kiov);
 989                if (!ret)
 990                        ret = __put_user(kiov.iov_len, &uiov->iov_len);
 991                break;
 992        }
 993#endif
 994
 995        default:
 996                ret = ptrace_request(child, request, addr, data);
 997        }
 998
 999        return ret;
1000}
1001
1002asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
1003                                  compat_long_t addr, compat_long_t data)
1004{
1005        struct task_struct *child;
1006        long ret;
1007
1008        if (request == PTRACE_TRACEME) {
1009                ret = ptrace_traceme();
1010                goto out;
1011        }
1012
1013        child = ptrace_get_task_struct(pid);
1014        if (IS_ERR(child)) {
1015                ret = PTR_ERR(child);
1016                goto out;
1017        }
1018
1019        if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1020                ret = ptrace_attach(child, request, addr, data);
1021                /*
1022                 * Some architectures need to do book-keeping after
1023                 * a ptrace attach.
1024                 */
1025                if (!ret)
1026                        arch_ptrace_attach(child);
1027                goto out_put_task_struct;
1028        }
1029
1030        ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1031                                  request == PTRACE_INTERRUPT);
1032        if (!ret)
1033                ret = compat_arch_ptrace(child, request, addr, data);
1034
1035 out_put_task_struct:
1036        put_task_struct(child);
1037 out:
1038        return ret;
1039}
1040#endif  /* CONFIG_COMPAT */
1041
1042#ifdef CONFIG_HAVE_HW_BREAKPOINT
1043int ptrace_get_breakpoints(struct task_struct *tsk)
1044{
1045        if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
1046                return 0;
1047
1048        return -1;
1049}
1050
1051void ptrace_put_breakpoints(struct task_struct *tsk)
1052{
1053        if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
1054                flush_ptrace_hw_breakpoint(tsk);
1055}
1056#endif /* CONFIG_HAVE_HW_BREAKPOINT */
1057
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