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