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->user->user_ns == tcred->user->user_ns &&
 139             (cred->uid == tcred->euid &&
 140              cred->uid == tcred->suid &&
 141              cred->uid == tcred->uid  &&
 142              cred->gid == tcred->egid &&
 143              cred->gid == tcred->sgid &&
 144              cred->gid == tcred->gid))
 145                 goto ok;
 146         if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
 147                 goto ok;
 148         rcu_read_unlock();
 149         return -EPERM;
 150 ok:
 151         rcu_read_unlock();
 152         smp_rmb();
 153         if (task->mm)
 154                 dumpable = get_dumpable(task->mm);
 155         if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
 156                 return -EPERM;
 157
 158         return security_ptrace_access_check(task, mode);
 159 }
 160
 161 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 162 {
 163         int err;
 164         task_lock(task);
 165         err = __ptrace_may_access(task, mode);
 166         task_unlock(task);
 167         return !err;
 168 }
 169
 170 static int ptrace_attach(struct task_struct *task)
 171 {
 172         int retval;
 173
 174         audit_ptrace(task);
 175
 176         retval = -EPERM;
 177         if (unlikely(task->flags & PF_KTHREAD))
 178                 goto out;
 179         if (same_thread_group(task, current))
 180                 goto out;
 181
 182         /*
 183          * Protect exec's credential calculations against our interference;
 184          * interference; SUID, SGID and LSM creds get determined differently
 185          * under ptrace.
 186          */
 187         retval = -ERESTARTNOINTR;
 188         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 189                 goto out;
 190
 191         task_lock(task);
 192         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 193         task_unlock(task);
 194         if (retval)
 195                 goto unlock_creds;
 196
 197         write_lock_irq(&tasklist_lock);
 198         retval = -EPERM;
 199         if (unlikely(task->exit_state))
 200                 goto unlock_tasklist;
 201         if (task->ptrace)
 202                 goto unlock_tasklist;
 203
 204         task->ptrace = PT_PTRACED;
 205         if (task_ns_capable(task, CAP_SYS_PTRACE))
 206                 task->ptrace |= PT_PTRACE_CAP;
 207
 208         __ptrace_link(task, current);
 209         send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 210
 211         retval = 0;
 212 unlock_tasklist:
 213         write_unlock_irq(&tasklist_lock);
 214 unlock_creds:
 215         mutex_unlock(&task->signal->cred_guard_mutex);
 216 out:
 217         return retval;
 218 }
 219
 220 /**
 221  * ptrace_traceme  --  helper for PTRACE_TRACEME
 222  *
 223  * Performs checks and sets PT_PTRACED.
 224  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 225  */
 226 static int ptrace_traceme(void)
 227 {
 228         int ret = -EPERM;
 229
 230         write_lock_irq(&tasklist_lock);
 231         /* Are we already being traced? */
 232         if (!current->ptrace) {
 233                 ret = security_ptrace_traceme(current->parent);
 234                 /*
 235                  * Check PF_EXITING to ensure ->real_parent has not passed
 236                  * exit_ptrace(). Otherwise we don't report the error but
 237                  * pretend ->real_parent untraces us right after return.
 238                  */
 239                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 240                         current->ptrace = PT_PTRACED;
 241                         __ptrace_link(current, current->real_parent);
 242                 }
 243         }
 244         write_unlock_irq(&tasklist_lock);
 245
 246         return ret;
 247 }
 248
 249 /*
 250  * Called with irqs disabled, returns true if childs should reap themselves.
 251  */
 252 static int ignoring_children(struct sighand_struct *sigh)
 253 {
 254         int ret;
 255         spin_lock(&sigh->siglock);
 256         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 257               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 258         spin_unlock(&sigh->siglock);
 259         return ret;
 260 }
 261
 262 /*
 263  * Called with tasklist_lock held for writing.
 264  * Unlink a traced task, and clean it up if it was a traced zombie.
 265  * Return true if it needs to be reaped with release_task().
 266  * (We can't call release_task() here because we already hold tasklist_lock.)
 267  *
 268  * If it's a zombie, our attachedness prevented normal parent notification
 269  * or self-reaping.  Do notification now if it would have happened earlier.
 270  * If it should reap itself, return true.
 271  *
 272  * If it's our own child, there is no notification to do. But if our normal
 273  * children self-reap, then this child was prevented by ptrace and we must
 274  * reap it now, in that case we must also wake up sub-threads sleeping in
 275  * do_wait().
 276  */
 277 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 278 {
 279         __ptrace_unlink(p);
 280
 281         if (p->exit_state == EXIT_ZOMBIE) {
 282                 if (!task_detached(p) && thread_group_empty(p)) {
 283                         if (!same_thread_group(p->real_parent, tracer))
 284                                 do_notify_parent(p, p->exit_signal);
 285                         else if (ignoring_children(tracer->sighand)) {
 286                                 __wake_up_parent(p, tracer);
 287                                 p->exit_signal = -1;
 288                         }
 289                 }
 290                 if (task_detached(p)) {
 291                         /* Mark it as in the process of being reaped. */
 292                         p->exit_state = EXIT_DEAD;
 293                         return true;
 294                 }
 295         }
 296
 297         return false;
 298 }
 299
 300 static int ptrace_detach(struct task_struct *child, unsigned int data)
 301 {
 302         bool dead = false;
 303
 304         if (!valid_signal(data))
 305                 return -EIO;
 306
 307         /* Architecture-specific hardware disable .. */
 308         ptrace_disable(child);
 309         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 310
 311         write_lock_irq(&tasklist_lock);
 312         /*
 313          * This child can be already killed. Make sure de_thread() or
 314          * our sub-thread doing do_wait() didn't do release_task() yet.
 315          */
 316         if (child->ptrace) {
 317                 child->exit_code = data;
 318                 dead = __ptrace_detach(current, child);
 319                 if (!child->exit_state)
 320                         wake_up_state(child, TASK_TRACED | TASK_STOPPED);
 321         }
 322         write_unlock_irq(&tasklist_lock);
 323
 324         if (unlikely(dead))
 325                 release_task(child);
 326
 327         return 0;
 328 }
 329
 330 /*
 331  * Detach all tasks we were using ptrace on. Called with tasklist held
 332  * for writing, and returns with it held too. But note it can release
 333  * and reacquire the lock.
 334  */
 335 void exit_ptrace(struct task_struct *tracer)
 336         __releases(&tasklist_lock)
 337         __acquires(&tasklist_lock)
 338 {
 339         struct task_struct *p, *n;
 340         LIST_HEAD(ptrace_dead);
 341
 342         if (likely(list_empty(&tracer->ptraced)))
 343                 return;
 344
 345         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 346                 if (__ptrace_detach(tracer, p))
 347                         list_add(&p->ptrace_entry, &ptrace_dead);
 348         }
 349
 350         write_unlock_irq(&tasklist_lock);
 351         BUG_ON(!list_empty(&tracer->ptraced));
 352
 353         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 354                 list_del_init(&p->ptrace_entry);
 355                 release_task(p);
 356         }
 357
 358         write_lock_irq(&tasklist_lock);
 359 }
 360
 361 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 362 {
 363         int copied = 0;
 364
 365         while (len > 0) {
 366                 char buf[128];
 367                 int this_len, retval;
 368
 369                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 370                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 371                 if (!retval) {
 372                         if (copied)
 373                                 break;
 374                         return -EIO;
 375                 }
 376                 if (copy_to_user(dst, buf, retval))
 377                         return -EFAULT;
 378                 copied += retval;
 379                 src += retval;
 380                 dst += retval;
 381                 len -= retval;
 382         }
 383         return copied;
 384 }
 385
 386 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 387 {
 388         int copied = 0;
 389
 390         while (len > 0) {
 391                 char buf[128];
 392                 int this_len, retval;
 393
 394                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 395                 if (copy_from_user(buf, src, this_len))
 396                         return -EFAULT;
 397                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 398                 if (!retval) {
 399                         if (copied)
 400                                 break;
 401                         return -EIO;
 402                 }
 403                 copied += retval;
 404                 src += retval;
 405                 dst += retval;
 406                 len -= retval;
 407         }
 408         return copied;
 409 }
 410
 411 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 412 {
 413         child->ptrace &= ~PT_TRACE_MASK;
 414
 415         if (data & PTRACE_O_TRACESYSGOOD)
 416                 child->ptrace |= PT_TRACESYSGOOD;
 417
 418         if (data & PTRACE_O_TRACEFORK)
 419                 child->ptrace |= PT_TRACE_FORK;
 420
 421         if (data & PTRACE_O_TRACEVFORK)
 422                 child->ptrace |= PT_TRACE_VFORK;
 423
 424         if (data & PTRACE_O_TRACECLONE)
 425                 child->ptrace |= PT_TRACE_CLONE;
 426
 427         if (data & PTRACE_O_TRACEEXEC)
 428                 child->ptrace |= PT_TRACE_EXEC;
 429
 430         if (data & PTRACE_O_TRACEVFORKDONE)
 431                 child->ptrace |= PT_TRACE_VFORK_DONE;
 432
 433         if (data & PTRACE_O_TRACEEXIT)
 434                 child->ptrace |= PT_TRACE_EXIT;
 435
 436         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 437 }
 438
 439 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 440 {
 441         unsigned long flags;
 442         int error = -ESRCH;
 443
 444         if (lock_task_sighand(child, &flags)) {
 445                 error = -EINVAL;
 446                 if (likely(child->last_siginfo != NULL)) {
 447                         *info = *child->last_siginfo;
 448                         error = 0;
 449                 }
 450                 unlock_task_sighand(child, &flags);
 451         }
 452         return error;
 453 }
 454
 455 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 456 {
 457         unsigned long flags;
 458         int error = -ESRCH;
 459
 460         if (lock_task_sighand(child, &flags)) {
 461                 error = -EINVAL;
 462                 if (likely(child->last_siginfo != NULL)) {
 463                         *child->last_siginfo = *info;
 464                         error = 0;
 465                 }
 466                 unlock_task_sighand(child, &flags);
 467         }
 468         return error;
 469 }
 470
 471
 472 #ifdef PTRACE_SINGLESTEP
 473 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 474 #else
 475 #define is_singlestep(request)          0
 476 #endif
 477
 478 #ifdef PTRACE_SINGLEBLOCK
 479 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 480 #else
 481 #define is_singleblock(request)         0
 482 #endif
 483
 484 #ifdef PTRACE_SYSEMU
 485 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 486 #else
 487 #define is_sysemu_singlestep(request)   0
 488 #endif
 489
 490 static int ptrace_resume(struct task_struct *child, long request,
 491                          unsigned long data)
 492 {
 493         if (!valid_signal(data))
 494                 return -EIO;
 495
 496         if (request == PTRACE_SYSCALL)
 497                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 498         else
 499                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 500
 501 #ifdef TIF_SYSCALL_EMU
 502         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 503                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 504         else
 505                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 506 #endif
 507
 508         if (is_singleblock(request)) {
 509                 if (unlikely(!arch_has_block_step()))
 510                         return -EIO;
 511                 user_enable_block_step(child);
 512         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 513                 if (unlikely(!arch_has_single_step()))
 514                         return -EIO;
 515                 user_enable_single_step(child);
 516         } else {
 517                 user_disable_single_step(child);
 518         }
 519
 520         child->exit_code = data;
 521         wake_up_process(child);
 522
 523         return 0;
 524 }
 525
 526 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 527
 528 static const struct user_regset *
 529 find_regset(const struct user_regset_view *view, unsigned int type)
 530 {
 531         const struct user_regset *regset;
 532         int n;
 533
 534         for (n = 0; n < view->n; ++n) {
 535                 regset = view->regsets + n;
 536                 if (regset->core_note_type == type)
 537                         return regset;
 538         }
 539
 540         return NULL;
 541 }
 542
 543 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 544                          struct iovec *kiov)
 545 {
 546         const struct user_regset_view *view = task_user_regset_view(task);
 547         const struct user_regset *regset = find_regset(view, type);
 548         int regset_no;
 549
 550         if (!regset || (kiov->iov_len % regset->size) != 0)
 551                 return -EINVAL;
 552
 553         regset_no = regset - view->regsets;
 554         kiov->iov_len = min(kiov->iov_len,
 555                             (__kernel_size_t) (regset->n * regset->size));
 556
 557         if (req == PTRACE_GETREGSET)
 558                 return copy_regset_to_user(task, view, regset_no, 0,
 559                                            kiov->iov_len, kiov->iov_base);
 560         else
 561                 return copy_regset_from_user(task, view, regset_no, 0,
 562                                              kiov->iov_len, kiov->iov_base);
 563 }
 564
 565 #endif
 566
 567 int ptrace_request(struct task_struct *child, long request,
 568                    unsigned long addr, unsigned long data)
 569 {
 570         int ret = -EIO;
 571         siginfo_t siginfo;
 572         void __user *datavp = (void __user *) data;
 573         unsigned long __user *datalp = datavp;
 574
 575         switch (request) {
 576         case PTRACE_PEEKTEXT:
 577         case PTRACE_PEEKDATA:
 578                 return generic_ptrace_peekdata(child, addr, data);
 579         case PTRACE_POKETEXT:
 580         case PTRACE_POKEDATA:
 581                 return generic_ptrace_pokedata(child, addr, data);
 582
 583 #ifdef PTRACE_OLDSETOPTIONS
 584         case PTRACE_OLDSETOPTIONS:
 585 #endif
 586         case PTRACE_SETOPTIONS:
 587                 ret = ptrace_setoptions(child, data);
 588                 break;
 589         case PTRACE_GETEVENTMSG:
 590                 ret = put_user(child->ptrace_message, datalp);
 591                 break;
 592
 593         case PTRACE_GETSIGINFO:
 594                 ret = ptrace_getsiginfo(child, &siginfo);
 595                 if (!ret)
 596                         ret = copy_siginfo_to_user(datavp, &siginfo);
 597                 break;
 598
 599         case PTRACE_SETSIGINFO:
 600                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 601                         ret = -EFAULT;
 602                 else
 603                         ret = ptrace_setsiginfo(child, &siginfo);
 604                 break;
 605
 606         case PTRACE_DETACH:      /* detach a process that was attached. */
 607                 ret = ptrace_detach(child, data);
 608                 break;
 609
 610 #ifdef CONFIG_BINFMT_ELF_FDPIC
 611         case PTRACE_GETFDPIC: {
 612                 struct mm_struct *mm = get_task_mm(child);
 613                 unsigned long tmp = 0;
 614
 615                 ret = -ESRCH;
 616                 if (!mm)
 617                         break;
 618
 619                 switch (addr) {
 620                 case PTRACE_GETFDPIC_EXEC:
 621                         tmp = mm->context.exec_fdpic_loadmap;
 622                         break;
 623                 case PTRACE_GETFDPIC_INTERP:
 624                         tmp = mm->context.interp_fdpic_loadmap;
 625                         break;
 626                 default:
 627                         break;
 628                 }
 629                 mmput(mm);
 630
 631                 ret = put_user(tmp, datalp);
 632                 break;
 633         }
 634 #endif
 635
 636 #ifdef PTRACE_SINGLESTEP
 637         case PTRACE_SINGLESTEP:
 638 #endif
 639 #ifdef PTRACE_SINGLEBLOCK
 640         case PTRACE_SINGLEBLOCK:
 641 #endif
 642 #ifdef PTRACE_SYSEMU
 643         case PTRACE_SYSEMU:
 644         case PTRACE_SYSEMU_SINGLESTEP:
 645 #endif
 646         case PTRACE_SYSCALL:
 647         case PTRACE_CONT:
 648                 return ptrace_resume(child, request, data);
 649
 650         case PTRACE_KILL:
 651                 if (child->exit_state)  /* already dead */
 652                         return 0;
 653                 return ptrace_resume(child, request, SIGKILL);
 654
 655 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 656         case PTRACE_GETREGSET:
 657         case PTRACE_SETREGSET:
 658         {
 659                 struct iovec kiov;
 660                 struct iovec __user *uiov = datavp;
 661
 662                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 663                         return -EFAULT;
 664
 665                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 666                     __get_user(kiov.iov_len, &uiov->iov_len))
 667                         return -EFAULT;
 668
 669                 ret = ptrace_regset(child, request, addr, &kiov);
 670                 if (!ret)
 671                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 672                 break;
 673         }
 674 #endif
 675         default:
 676                 break;
 677         }
 678
 679         return ret;
 680 }
 681
 682 static struct task_struct *ptrace_get_task_struct(pid_t pid)
 683 {
 684         struct task_struct *child;
 685
 686         rcu_read_lock();
 687         child = find_task_by_vpid(pid);
 688         if (child)
 689                 get_task_struct(child);
 690         rcu_read_unlock();
 691
 692         if (!child)
 693                 return ERR_PTR(-ESRCH);
 694         return child;
 695 }
 696
 697 #ifndef arch_ptrace_attach
 698 #define arch_ptrace_attach(child)       do { } while (0)
 699 #endif
 700
 701 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 702                 unsigned long, data)
 703 {
 704         struct task_struct *child;
 705         long ret;
 706
 707         if (request == PTRACE_TRACEME) {
 708                 ret = ptrace_traceme();
 709                 if (!ret)
 710                         arch_ptrace_attach(current);
 711                 goto out;
 712         }
 713
 714         child = ptrace_get_task_struct(pid);
 715         if (IS_ERR(child)) {
 716                 ret = PTR_ERR(child);
 717                 goto out;
 718         }
 719
 720         if (request == PTRACE_ATTACH) {
 721                 ret = ptrace_attach(child);
 722                 /*
 723                  * Some architectures need to do book-keeping after
 724                  * a ptrace attach.
 725                  */
 726                 if (!ret)
 727                         arch_ptrace_attach(child);
 728                 goto out_put_task_struct;
 729         }
 730
 731         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 732         if (ret < 0)
 733                 goto out_put_task_struct;
 734
 735         ret = arch_ptrace(child, request, addr, data);
 736
 737  out_put_task_struct:
 738         put_task_struct(child);
 739  out:
 740         return ret;
 741 }
 742
 743 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 744                             unsigned long data)
 745 {
 746         unsigned long tmp;
 747         int copied;
 748
 749         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 750         if (copied != sizeof(tmp))
 751                 return -EIO;
 752         return put_user(tmp, (unsigned long __user *)data);
 753 }
 754
 755 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 756                             unsigned long data)
 757 {
 758         int copied;
 759
 760         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 761         return (copied == sizeof(data)) ? 0 : -EIO;
 762 }
 763
 764 #if defined CONFIG_COMPAT
 765 #include <linux/compat.h>
 766
 767 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 768                           compat_ulong_t addr, compat_ulong_t data)
 769 {
 770         compat_ulong_t __user *datap = compat_ptr(data);
 771         compat_ulong_t word;
 772         siginfo_t siginfo;
 773         int ret;
 774
 775         switch (request) {
 776         case PTRACE_PEEKTEXT:
 777         case PTRACE_PEEKDATA:
 778                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 779                 if (ret != sizeof(word))
 780                         ret = -EIO;
 781                 else
 782                         ret = put_user(word, datap);
 783                 break;
 784
 785         case PTRACE_POKETEXT:
 786         case PTRACE_POKEDATA:
 787                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 788                 ret = (ret != sizeof(data) ? -EIO : 0);
 789                 break;
 790
 791         case PTRACE_GETEVENTMSG:
 792                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 793                 break;
 794
 795         case PTRACE_GETSIGINFO:
 796                 ret = ptrace_getsiginfo(child, &siginfo);
 797                 if (!ret)
 798                         ret = copy_siginfo_to_user32(
 799                                 (struct compat_siginfo __user *) datap,
 800                                 &siginfo);
 801                 break;
 802
 803         case PTRACE_SETSIGINFO:
 804                 memset(&siginfo, 0, sizeof siginfo);
 805                 if (copy_siginfo_from_user32(
 806                             &siginfo, (struct compat_siginfo __user *) datap))
 807                         ret = -EFAULT;
 808                 else
 809                         ret = ptrace_setsiginfo(child, &siginfo);
 810                 break;
 811 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 812         case PTRACE_GETREGSET:
 813         case PTRACE_SETREGSET:
 814         {
 815                 struct iovec kiov;
 816                 struct compat_iovec __user *uiov =
 817                         (struct compat_iovec __user *) datap;
 818                 compat_uptr_t ptr;
 819                 compat_size_t len;
 820
 821                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 822                         return -EFAULT;
 823
 824                 if (__get_user(ptr, &uiov->iov_base) ||
 825                     __get_user(len, &uiov->iov_len))
 826                         return -EFAULT;
 827
 828                 kiov.iov_base = compat_ptr(ptr);
 829                 kiov.iov_len = len;
 830
 831                 ret = ptrace_regset(child, request, addr, &kiov);
 832                 if (!ret)
 833                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 834                 break;
 835         }
 836 #endif
 837
 838         default:
 839                 ret = ptrace_request(child, request, addr, data);
 840         }
 841
 842         return ret;
 843 }
 844
 845 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 846                                   compat_long_t addr, compat_long_t data)
 847 {
 848         struct task_struct *child;
 849         long ret;
 850
 851         if (request == PTRACE_TRACEME) {
 852                 ret = ptrace_traceme();
 853                 goto out;
 854         }
 855
 856         child = ptrace_get_task_struct(pid);
 857         if (IS_ERR(child)) {
 858                 ret = PTR_ERR(child);
 859                 goto out;
 860         }
 861
 862         if (request == PTRACE_ATTACH) {
 863                 ret = ptrace_attach(child);
 864                 /*
 865                  * Some architectures need to do book-keeping after
 866                  * a ptrace attach.
 867                  */
 868                 if (!ret)
 869                         arch_ptrace_attach(child);
 870                 goto out_put_task_struct;
 871         }
 872
 873         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 874         if (!ret)
 875                 ret = compat_arch_ptrace(child, request, addr, data);
 876
 877  out_put_task_struct:
 878         put_task_struct(child);
 879  out:
 880         return ret;
 881 }
 882 #endif  /* CONFIG_COMPAT */
 883
 884 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 885 int ptrace_get_breakpoints(struct task_struct *tsk)
 886 {
 887         if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
 888                 return 0;
 889
 890         return -1;
 891 }
 892
 893 void ptrace_put_breakpoints(struct task_struct *tsk)
 894 {
 895         if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
 896                 flush_ptrace_hw_breakpoint(tsk);
 897 }
 898 #endif /* CONFIG_HAVE_HW_BREAKPOINT */