kernel/ptrace.c

   1 /*
   2  * linux/kernel/ptrace.c
   3  *
   4  * (C) Copyright 1999 Linus Torvalds
   5  *
   6  * Common interfaces for "ptrace()" which we do not want
   7  * to continually duplicate across every architecture.
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/errno.h>
  14 #include <linux/mm.h>
  15 #include <linux/highmem.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/security.h>
  19 #include <linux/signal.h>
  20 #include <linux/audit.h>
  21 #include <linux/pid_namespace.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/regset.h>
  25 #include <linux/hw_breakpoint.h>
  26
  27
  28 /*
  29  * ptrace a task: make the debugger its new parent and
  30  * move it to the ptrace list.
  31  *
  32  * Must be called with the tasklist lock write-held.
  33  */
  34 void __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  */
  48 static 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  */
  71 void __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  */
  86 int 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
 120 int __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
 158 bool 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
 167 static 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;
 209 unlock_tasklist:
 210         write_unlock_irq(&tasklist_lock);
 211 unlock_creds:
 212         mutex_unlock(&task->signal->cred_guard_mutex);
 213 out:
 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  */
 223 static 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  */
 249 static 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  */
 274 static 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
 297 static 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  */
 332 void 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
 358 int 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
 383 int 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
 408 static 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
 436 static 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
 452 static 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
 487 static 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
 525 static const struct user_regset *
 526 find_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
 540 static 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
 564 int 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
 679 static 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
 698 SYSCALL_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
 740 int 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
 752 int 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
 764 int 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
 842 asmlinkage 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
 882 int 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
 890 void 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 */