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