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