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  * __ptrace_unlink - unlink ptracee and restore its execution state
  43  * @child: ptracee to be unlinked
  44  *
  45  * Remove @child from the ptrace list, move it back to the original parent,
  46  * and restore the execution state so that it conforms to the group stop
  47  * state.
  48  *
  49  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  50  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  51  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  52  * If the ptracer is exiting, the ptracee can be in any state.
  53  *
  54  * After detach, the ptracee should be in a state which conforms to the
  55  * group stop.  If the group is stopped or in the process of stopping, the
  56  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  57  * up from TASK_TRACED.
  58  *
  59  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  60  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  61  * to but in the opposite direction of what happens while attaching to a
  62  * stopped task.  However, in this direction, the intermediate RUNNING
  63  * state is not hidden even from the current ptracer and if it immediately
  64  * re-attaches and performs a WNOHANG wait(2), it may fail.
  65  *
  66  * CONTEXT:
  67  * write_lock_irq(tasklist_lock)
  68  */
  69 void __ptrace_unlink(struct task_struct *child)
  70 {
  71         BUG_ON(!child->ptrace);
  72
  73         child->ptrace = 0;
  74         child->parent = child->real_parent;
  75         list_del_init(&child->ptrace_entry);
  76
  77         spin_lock(&child->sighand->siglock);
  78
  79         /*
  80          * Reinstate GROUP_STOP_PENDING if group stop is in effect and
  81          * @child isn't dead.
  82          */
  83         if (!(child->flags & PF_EXITING) &&
  84             (child->signal->flags & SIGNAL_STOP_STOPPED ||
  85              child->signal->group_stop_count))
  86                 child->group_stop |= GROUP_STOP_PENDING;
  87
  88         /*
  89          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
  90          * @child in the butt.  Note that @resume should be used iff @child
  91          * is in TASK_TRACED; otherwise, we might unduly disrupt
  92          * TASK_KILLABLE sleeps.
  93          */
  94         if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
  95                 signal_wake_up(child, task_is_traced(child));
  96
  97         spin_unlock(&child->sighand->siglock);
  98 }
  99
 100 /*
 101  * Check that we have indeed attached to the thing..
 102  */
 103 int ptrace_check_attach(struct task_struct *child, int kill)
 104 {
 105         int ret = -ESRCH;
 106
 107         /*
 108          * We take the read lock around doing both checks to close a
 109          * possible race where someone else was tracing our child and
 110          * detached between these two checks.  After this locked check,
 111          * we are sure that this is our traced child and that can only
 112          * be changed by us so it's not changing right after this.
 113          */
 114         read_lock(&tasklist_lock);
 115         if ((child->ptrace & PT_PTRACED) && child->parent == current) {
 116                 /*
 117                  * child->sighand can't be NULL, release_task()
 118                  * does ptrace_unlink() before __exit_signal().
 119                  */
 120                 spin_lock_irq(&child->sighand->siglock);
 121                 WARN_ON_ONCE(task_is_stopped(child));
 122                 if (task_is_traced(child) || kill)
 123                         ret = 0;
 124                 spin_unlock_irq(&child->sighand->siglock);
 125         }
 126         read_unlock(&tasklist_lock);
 127
 128         if (!ret && !kill)
 129                 ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 130
 131         /* All systems go.. */
 132         return ret;
 133 }
 134
 135 int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 136 {
 137         const struct cred *cred = current_cred(), *tcred;
 138
 139         /* May we inspect the given task?
 140          * This check is used both for attaching with ptrace
 141          * and for allowing access to sensitive information in /proc.
 142          *
 143          * ptrace_attach denies several cases that /proc allows
 144          * because setting up the necessary parent/child relationship
 145          * or halting the specified task is impossible.
 146          */
 147         int dumpable = 0;
 148         /* Don't let security modules deny introspection */
 149         if (task == current)
 150                 return 0;
 151         rcu_read_lock();
 152         tcred = __task_cred(task);
 153         if (cred->user->user_ns == tcred->user->user_ns &&
 154             (cred->uid == tcred->euid &&
 155              cred->uid == tcred->suid &&
 156              cred->uid == tcred->uid  &&
 157              cred->gid == tcred->egid &&
 158              cred->gid == tcred->sgid &&
 159              cred->gid == tcred->gid))
 160                 goto ok;
 161         if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
 162                 goto ok;
 163         rcu_read_unlock();
 164         return -EPERM;
 165 ok:
 166         rcu_read_unlock();
 167         smp_rmb();
 168         if (task->mm)
 169                 dumpable = get_dumpable(task->mm);
 170         if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
 171                 return -EPERM;
 172
 173         return security_ptrace_access_check(task, mode);
 174 }
 175
 176 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 177 {
 178         int err;
 179         task_lock(task);
 180         err = __ptrace_may_access(task, mode);
 181         task_unlock(task);
 182         return !err;
 183 }
 184
 185 static int ptrace_attach(struct task_struct *task)
 186 {
 187         bool wait_trap = false;
 188         int retval;
 189
 190         audit_ptrace(task);
 191
 192         retval = -EPERM;
 193         if (unlikely(task->flags & PF_KTHREAD))
 194                 goto out;
 195         if (same_thread_group(task, current))
 196                 goto out;
 197
 198         /*
 199          * Protect exec's credential calculations against our interference;
 200          * interference; SUID, SGID and LSM creds get determined differently
 201          * under ptrace.
 202          */
 203         retval = -ERESTARTNOINTR;
 204         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 205                 goto out;
 206
 207         task_lock(task);
 208         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 209         task_unlock(task);
 210         if (retval)
 211                 goto unlock_creds;
 212
 213         write_lock_irq(&tasklist_lock);
 214         retval = -EPERM;
 215         if (unlikely(task->exit_state))
 216                 goto unlock_tasklist;
 217         if (task->ptrace)
 218                 goto unlock_tasklist;
 219
 220         task->ptrace = PT_PTRACED;
 221         if (task_ns_capable(task, CAP_SYS_PTRACE))
 222                 task->ptrace |= PT_PTRACE_CAP;
 223
 224         __ptrace_link(task, current);
 225         send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 226
 227         spin_lock(&task->sighand->siglock);
 228
 229         /*
 230          * If the task is already STOPPED, set GROUP_STOP_PENDING and
 231          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 232          * will be cleared if the child completes the transition or any
 233          * event which clears the group stop states happens.  We'll wait
 234          * for the transition to complete before returning from this
 235          * function.
 236          *
 237          * This hides STOPPED -> RUNNING -> TRACED transition from the
 238          * attaching thread but a different thread in the same group can
 239          * still observe the transient RUNNING state.  IOW, if another
 240          * thread's WNOHANG wait(2) on the stopped tracee races against
 241          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 242          *
 243          * The following task_is_stopped() test is safe as both transitions
 244          * in and out of STOPPED are protected by siglock.
 245          */
 246         if (task_is_stopped(task)) {
 247                 task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
 248                 signal_wake_up(task, 1);
 249                 wait_trap = true;
 250         }
 251
 252         spin_unlock(&task->sighand->siglock);
 253
 254         retval = 0;
 255 unlock_tasklist:
 256         write_unlock_irq(&tasklist_lock);
 257 unlock_creds:
 258         mutex_unlock(&task->signal->cred_guard_mutex);
 259 out:
 260         if (wait_trap)
 261                 wait_event(current->signal->wait_chldexit,
 262                            !(task->group_stop & GROUP_STOP_TRAPPING));
 263         return retval;
 264 }
 265
 266 /**
 267  * ptrace_traceme  --  helper for PTRACE_TRACEME
 268  *
 269  * Performs checks and sets PT_PTRACED.
 270  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 271  */
 272 static int ptrace_traceme(void)
 273 {
 274         int ret = -EPERM;
 275
 276         write_lock_irq(&tasklist_lock);
 277         /* Are we already being traced? */
 278         if (!current->ptrace) {
 279                 ret = security_ptrace_traceme(current->parent);
 280                 /*
 281                  * Check PF_EXITING to ensure ->real_parent has not passed
 282                  * exit_ptrace(). Otherwise we don't report the error but
 283                  * pretend ->real_parent untraces us right after return.
 284                  */
 285                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 286                         current->ptrace = PT_PTRACED;
 287                         __ptrace_link(current, current->real_parent);
 288                 }
 289         }
 290         write_unlock_irq(&tasklist_lock);
 291
 292         return ret;
 293 }
 294
 295 /*
 296  * Called with irqs disabled, returns true if childs should reap themselves.
 297  */
 298 static int ignoring_children(struct sighand_struct *sigh)
 299 {
 300         int ret;
 301         spin_lock(&sigh->siglock);
 302         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 303               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 304         spin_unlock(&sigh->siglock);
 305         return ret;
 306 }
 307
 308 /*
 309  * Called with tasklist_lock held for writing.
 310  * Unlink a traced task, and clean it up if it was a traced zombie.
 311  * Return true if it needs to be reaped with release_task().
 312  * (We can't call release_task() here because we already hold tasklist_lock.)
 313  *
 314  * If it's a zombie, our attachedness prevented normal parent notification
 315  * or self-reaping.  Do notification now if it would have happened earlier.
 316  * If it should reap itself, return true.
 317  *
 318  * If it's our own child, there is no notification to do. But if our normal
 319  * children self-reap, then this child was prevented by ptrace and we must
 320  * reap it now, in that case we must also wake up sub-threads sleeping in
 321  * do_wait().
 322  */
 323 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 324 {
 325         __ptrace_unlink(p);
 326
 327         if (p->exit_state == EXIT_ZOMBIE) {
 328                 if (!task_detached(p) && thread_group_empty(p)) {
 329                         if (!same_thread_group(p->real_parent, tracer))
 330                                 do_notify_parent(p, p->exit_signal);
 331                         else if (ignoring_children(tracer->sighand)) {
 332                                 __wake_up_parent(p, tracer);
 333                                 p->exit_signal = -1;
 334                         }
 335                 }
 336                 if (task_detached(p)) {
 337                         /* Mark it as in the process of being reaped. */
 338                         p->exit_state = EXIT_DEAD;
 339                         return true;
 340                 }
 341         }
 342
 343         return false;
 344 }
 345
 346 static int ptrace_detach(struct task_struct *child, unsigned int data)
 347 {
 348         bool dead = false;
 349
 350         if (!valid_signal(data))
 351                 return -EIO;
 352
 353         /* Architecture-specific hardware disable .. */
 354         ptrace_disable(child);
 355         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 356
 357         write_lock_irq(&tasklist_lock);
 358         /*
 359          * This child can be already killed. Make sure de_thread() or
 360          * our sub-thread doing do_wait() didn't do release_task() yet.
 361          */
 362         if (child->ptrace) {
 363                 child->exit_code = data;
 364                 dead = __ptrace_detach(current, child);
 365         }
 366         write_unlock_irq(&tasklist_lock);
 367
 368         if (unlikely(dead))
 369                 release_task(child);
 370
 371         return 0;
 372 }
 373
 374 /*
 375  * Detach all tasks we were using ptrace on. Called with tasklist held
 376  * for writing, and returns with it held too. But note it can release
 377  * and reacquire the lock.
 378  */
 379 void exit_ptrace(struct task_struct *tracer)
 380         __releases(&tasklist_lock)
 381         __acquires(&tasklist_lock)
 382 {
 383         struct task_struct *p, *n;
 384         LIST_HEAD(ptrace_dead);
 385
 386         if (likely(list_empty(&tracer->ptraced)))
 387                 return;
 388
 389         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 390                 if (__ptrace_detach(tracer, p))
 391                         list_add(&p->ptrace_entry, &ptrace_dead);
 392         }
 393
 394         write_unlock_irq(&tasklist_lock);
 395         BUG_ON(!list_empty(&tracer->ptraced));
 396
 397         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 398                 list_del_init(&p->ptrace_entry);
 399                 release_task(p);
 400         }
 401
 402         write_lock_irq(&tasklist_lock);
 403 }
 404
 405 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 406 {
 407         int copied = 0;
 408
 409         while (len > 0) {
 410                 char buf[128];
 411                 int this_len, retval;
 412
 413                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 414                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 415                 if (!retval) {
 416                         if (copied)
 417                                 break;
 418                         return -EIO;
 419                 }
 420                 if (copy_to_user(dst, buf, retval))
 421                         return -EFAULT;
 422                 copied += retval;
 423                 src += retval;
 424                 dst += retval;
 425                 len -= retval;
 426         }
 427         return copied;
 428 }
 429
 430 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 431 {
 432         int copied = 0;
 433
 434         while (len > 0) {
 435                 char buf[128];
 436                 int this_len, retval;
 437
 438                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 439                 if (copy_from_user(buf, src, this_len))
 440                         return -EFAULT;
 441                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 442                 if (!retval) {
 443                         if (copied)
 444                                 break;
 445                         return -EIO;
 446                 }
 447                 copied += retval;
 448                 src += retval;
 449                 dst += retval;
 450                 len -= retval;
 451         }
 452         return copied;
 453 }
 454
 455 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 456 {
 457         child->ptrace &= ~PT_TRACE_MASK;
 458
 459         if (data & PTRACE_O_TRACESYSGOOD)
 460                 child->ptrace |= PT_TRACESYSGOOD;
 461
 462         if (data & PTRACE_O_TRACEFORK)
 463                 child->ptrace |= PT_TRACE_FORK;
 464
 465         if (data & PTRACE_O_TRACEVFORK)
 466                 child->ptrace |= PT_TRACE_VFORK;
 467
 468         if (data & PTRACE_O_TRACECLONE)
 469                 child->ptrace |= PT_TRACE_CLONE;
 470
 471         if (data & PTRACE_O_TRACEEXEC)
 472                 child->ptrace |= PT_TRACE_EXEC;
 473
 474         if (data & PTRACE_O_TRACEVFORKDONE)
 475                 child->ptrace |= PT_TRACE_VFORK_DONE;
 476
 477         if (data & PTRACE_O_TRACEEXIT)
 478                 child->ptrace |= PT_TRACE_EXIT;
 479
 480         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 481 }
 482
 483 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 484 {
 485         unsigned long flags;
 486         int error = -ESRCH;
 487
 488         if (lock_task_sighand(child, &flags)) {
 489                 error = -EINVAL;
 490                 if (likely(child->last_siginfo != NULL)) {
 491                         *info = *child->last_siginfo;
 492                         error = 0;
 493                 }
 494                 unlock_task_sighand(child, &flags);
 495         }
 496         return error;
 497 }
 498
 499 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 500 {
 501         unsigned long flags;
 502         int error = -ESRCH;
 503
 504         if (lock_task_sighand(child, &flags)) {
 505                 error = -EINVAL;
 506                 if (likely(child->last_siginfo != NULL)) {
 507                         *child->last_siginfo = *info;
 508                         error = 0;
 509                 }
 510                 unlock_task_sighand(child, &flags);
 511         }
 512         return error;
 513 }
 514
 515
 516 #ifdef PTRACE_SINGLESTEP
 517 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 518 #else
 519 #define is_singlestep(request)          0
 520 #endif
 521
 522 #ifdef PTRACE_SINGLEBLOCK
 523 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 524 #else
 525 #define is_singleblock(request)         0
 526 #endif
 527
 528 #ifdef PTRACE_SYSEMU
 529 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 530 #else
 531 #define is_sysemu_singlestep(request)   0
 532 #endif
 533
 534 static int ptrace_resume(struct task_struct *child, long request,
 535                          unsigned long data)
 536 {
 537         if (!valid_signal(data))
 538                 return -EIO;
 539
 540         if (request == PTRACE_SYSCALL)
 541                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 542         else
 543                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 544
 545 #ifdef TIF_SYSCALL_EMU
 546         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 547                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 548         else
 549                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 550 #endif
 551
 552         if (is_singleblock(request)) {
 553                 if (unlikely(!arch_has_block_step()))
 554                         return -EIO;
 555                 user_enable_block_step(child);
 556         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 557                 if (unlikely(!arch_has_single_step()))
 558                         return -EIO;
 559                 user_enable_single_step(child);
 560         } else {
 561                 user_disable_single_step(child);
 562         }
 563
 564         child->exit_code = data;
 565         wake_up_state(child, __TASK_TRACED);
 566
 567         return 0;
 568 }
 569
 570 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 571
 572 static const struct user_regset *
 573 find_regset(const struct user_regset_view *view, unsigned int type)
 574 {
 575         const struct user_regset *regset;
 576         int n;
 577
 578         for (n = 0; n < view->n; ++n) {
 579                 regset = view->regsets + n;
 580                 if (regset->core_note_type == type)
 581                         return regset;
 582         }
 583
 584         return NULL;
 585 }
 586
 587 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 588                          struct iovec *kiov)
 589 {
 590         const struct user_regset_view *view = task_user_regset_view(task);
 591         const struct user_regset *regset = find_regset(view, type);
 592         int regset_no;
 593
 594         if (!regset || (kiov->iov_len % regset->size) != 0)
 595                 return -EINVAL;
 596
 597         regset_no = regset - view->regsets;
 598         kiov->iov_len = min(kiov->iov_len,
 599                             (__kernel_size_t) (regset->n * regset->size));
 600
 601         if (req == PTRACE_GETREGSET)
 602                 return copy_regset_to_user(task, view, regset_no, 0,
 603                                            kiov->iov_len, kiov->iov_base);
 604         else
 605                 return copy_regset_from_user(task, view, regset_no, 0,
 606                                              kiov->iov_len, kiov->iov_base);
 607 }
 608
 609 #endif
 610
 611 int ptrace_request(struct task_struct *child, long request,
 612                    unsigned long addr, unsigned long data)
 613 {
 614         int ret = -EIO;
 615         siginfo_t siginfo;
 616         void __user *datavp = (void __user *) data;
 617         unsigned long __user *datalp = datavp;
 618
 619         switch (request) {
 620         case PTRACE_PEEKTEXT:
 621         case PTRACE_PEEKDATA:
 622                 return generic_ptrace_peekdata(child, addr, data);
 623         case PTRACE_POKETEXT:
 624         case PTRACE_POKEDATA:
 625                 return generic_ptrace_pokedata(child, addr, data);
 626
 627 #ifdef PTRACE_OLDSETOPTIONS
 628         case PTRACE_OLDSETOPTIONS:
 629 #endif
 630         case PTRACE_SETOPTIONS:
 631                 ret = ptrace_setoptions(child, data);
 632                 break;
 633         case PTRACE_GETEVENTMSG:
 634                 ret = put_user(child->ptrace_message, datalp);
 635                 break;
 636
 637         case PTRACE_GETSIGINFO:
 638                 ret = ptrace_getsiginfo(child, &siginfo);
 639                 if (!ret)
 640                         ret = copy_siginfo_to_user(datavp, &siginfo);
 641                 break;
 642
 643         case PTRACE_SETSIGINFO:
 644                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 645                         ret = -EFAULT;
 646                 else
 647                         ret = ptrace_setsiginfo(child, &siginfo);
 648                 break;
 649
 650         case PTRACE_DETACH:      /* detach a process that was attached. */
 651                 ret = ptrace_detach(child, data);
 652                 break;
 653
 654 #ifdef CONFIG_BINFMT_ELF_FDPIC
 655         case PTRACE_GETFDPIC: {
 656                 struct mm_struct *mm = get_task_mm(child);
 657                 unsigned long tmp = 0;
 658
 659                 ret = -ESRCH;
 660                 if (!mm)
 661                         break;
 662
 663                 switch (addr) {
 664                 case PTRACE_GETFDPIC_EXEC:
 665                         tmp = mm->context.exec_fdpic_loadmap;
 666                         break;
 667                 case PTRACE_GETFDPIC_INTERP:
 668                         tmp = mm->context.interp_fdpic_loadmap;
 669                         break;
 670                 default:
 671                         break;
 672                 }
 673                 mmput(mm);
 674
 675                 ret = put_user(tmp, datalp);
 676                 break;
 677         }
 678 #endif
 679
 680 #ifdef PTRACE_SINGLESTEP
 681         case PTRACE_SINGLESTEP:
 682 #endif
 683 #ifdef PTRACE_SINGLEBLOCK
 684         case PTRACE_SINGLEBLOCK:
 685 #endif
 686 #ifdef PTRACE_SYSEMU
 687         case PTRACE_SYSEMU:
 688         case PTRACE_SYSEMU_SINGLESTEP:
 689 #endif
 690         case PTRACE_SYSCALL:
 691         case PTRACE_CONT:
 692                 return ptrace_resume(child, request, data);
 693
 694         case PTRACE_KILL:
 695                 if (child->exit_state)  /* already dead */
 696                         return 0;
 697                 return ptrace_resume(child, request, SIGKILL);
 698
 699 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 700         case PTRACE_GETREGSET:
 701         case PTRACE_SETREGSET:
 702         {
 703                 struct iovec kiov;
 704                 struct iovec __user *uiov = datavp;
 705
 706                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 707                         return -EFAULT;
 708
 709                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 710                     __get_user(kiov.iov_len, &uiov->iov_len))
 711                         return -EFAULT;
 712
 713                 ret = ptrace_regset(child, request, addr, &kiov);
 714                 if (!ret)
 715                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 716                 break;
 717         }
 718 #endif
 719         default:
 720                 break;
 721         }
 722
 723         return ret;
 724 }
 725
 726 static struct task_struct *ptrace_get_task_struct(pid_t pid)
 727 {
 728         struct task_struct *child;
 729
 730         rcu_read_lock();
 731         child = find_task_by_vpid(pid);
 732         if (child)
 733                 get_task_struct(child);
 734         rcu_read_unlock();
 735
 736         if (!child)
 737                 return ERR_PTR(-ESRCH);
 738         return child;
 739 }
 740
 741 #ifndef arch_ptrace_attach
 742 #define arch_ptrace_attach(child)       do { } while (0)
 743 #endif
 744
 745 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 746                 unsigned long, data)
 747 {
 748         struct task_struct *child;
 749         long ret;
 750
 751         if (request == PTRACE_TRACEME) {
 752                 ret = ptrace_traceme();
 753                 if (!ret)
 754                         arch_ptrace_attach(current);
 755                 goto out;
 756         }
 757
 758         child = ptrace_get_task_struct(pid);
 759         if (IS_ERR(child)) {
 760                 ret = PTR_ERR(child);
 761                 goto out;
 762         }
 763
 764         if (request == PTRACE_ATTACH) {
 765                 ret = ptrace_attach(child);
 766                 /*
 767                  * Some architectures need to do book-keeping after
 768                  * a ptrace attach.
 769                  */
 770                 if (!ret)
 771                         arch_ptrace_attach(child);
 772                 goto out_put_task_struct;
 773         }
 774
 775         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 776         if (ret < 0)
 777                 goto out_put_task_struct;
 778
 779         ret = arch_ptrace(child, request, addr, data);
 780
 781  out_put_task_struct:
 782         put_task_struct(child);
 783  out:
 784         return ret;
 785 }
 786
 787 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 788                             unsigned long data)
 789 {
 790         unsigned long tmp;
 791         int copied;
 792
 793         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 794         if (copied != sizeof(tmp))
 795                 return -EIO;
 796         return put_user(tmp, (unsigned long __user *)data);
 797 }
 798
 799 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 800                             unsigned long data)
 801 {
 802         int copied;
 803
 804         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 805         return (copied == sizeof(data)) ? 0 : -EIO;
 806 }
 807
 808 #if defined CONFIG_COMPAT
 809 #include <linux/compat.h>
 810
 811 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 812                           compat_ulong_t addr, compat_ulong_t data)
 813 {
 814         compat_ulong_t __user *datap = compat_ptr(data);
 815         compat_ulong_t word;
 816         siginfo_t siginfo;
 817         int ret;
 818
 819         switch (request) {
 820         case PTRACE_PEEKTEXT:
 821         case PTRACE_PEEKDATA:
 822                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 823                 if (ret != sizeof(word))
 824                         ret = -EIO;
 825                 else
 826                         ret = put_user(word, datap);
 827                 break;
 828
 829         case PTRACE_POKETEXT:
 830         case PTRACE_POKEDATA:
 831                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 832                 ret = (ret != sizeof(data) ? -EIO : 0);
 833                 break;
 834
 835         case PTRACE_GETEVENTMSG:
 836                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 837                 break;
 838
 839         case PTRACE_GETSIGINFO:
 840                 ret = ptrace_getsiginfo(child, &siginfo);
 841                 if (!ret)
 842                         ret = copy_siginfo_to_user32(
 843                                 (struct compat_siginfo __user *) datap,
 844                                 &siginfo);
 845                 break;
 846
 847         case PTRACE_SETSIGINFO:
 848                 memset(&siginfo, 0, sizeof siginfo);
 849                 if (copy_siginfo_from_user32(
 850                             &siginfo, (struct compat_siginfo __user *) datap))
 851                         ret = -EFAULT;
 852                 else
 853                         ret = ptrace_setsiginfo(child, &siginfo);
 854                 break;
 855 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 856         case PTRACE_GETREGSET:
 857         case PTRACE_SETREGSET:
 858         {
 859                 struct iovec kiov;
 860                 struct compat_iovec __user *uiov =
 861                         (struct compat_iovec __user *) datap;
 862                 compat_uptr_t ptr;
 863                 compat_size_t len;
 864
 865                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 866                         return -EFAULT;
 867
 868                 if (__get_user(ptr, &uiov->iov_base) ||
 869                     __get_user(len, &uiov->iov_len))
 870                         return -EFAULT;
 871
 872                 kiov.iov_base = compat_ptr(ptr);
 873                 kiov.iov_len = len;
 874
 875                 ret = ptrace_regset(child, request, addr, &kiov);
 876                 if (!ret)
 877                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 878                 break;
 879         }
 880 #endif
 881
 882         default:
 883                 ret = ptrace_request(child, request, addr, data);
 884         }
 885
 886         return ret;
 887 }
 888
 889 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 890                                   compat_long_t addr, compat_long_t data)
 891 {
 892         struct task_struct *child;
 893         long ret;
 894
 895         if (request == PTRACE_TRACEME) {
 896                 ret = ptrace_traceme();
 897                 goto out;
 898         }
 899
 900         child = ptrace_get_task_struct(pid);
 901         if (IS_ERR(child)) {
 902                 ret = PTR_ERR(child);
 903                 goto out;
 904         }
 905
 906         if (request == PTRACE_ATTACH) {
 907                 ret = ptrace_attach(child);
 908                 /*
 909                  * Some architectures need to do book-keeping after
 910                  * a ptrace attach.
 911                  */
 912                 if (!ret)
 913                         arch_ptrace_attach(child);
 914                 goto out_put_task_struct;
 915         }
 916
 917         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 918         if (!ret)
 919                 ret = compat_arch_ptrace(child, request, addr, data);
 920
 921  out_put_task_struct:
 922         put_task_struct(child);
 923  out:
 924         return ret;
 925 }
 926 #endif  /* CONFIG_COMPAT */
 927
 928 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 929 int ptrace_get_breakpoints(struct task_struct *tsk)
 930 {
 931         if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
 932                 return 0;
 933
 934         return -1;
 935 }
 936
 937 void ptrace_put_breakpoints(struct task_struct *tsk)
 938 {
 939         if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
 940                 flush_ptrace_hw_breakpoint(tsk);
 941 }
 942 #endif /* CONFIG_HAVE_HW_BREAKPOINT */