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 /* Ensure that nothing can wake it up, even SIGKILL */
  42 static bool ptrace_freeze_traced(struct task_struct *task)
  43 {
  44         bool ret = false;
  45
  46         spin_lock_irq(&task->sighand->siglock);
  47         if (task_is_traced(task) && !__fatal_signal_pending(task)) {
  48                 task->state = __TASK_TRACED;
  49                 ret = true;
  50         }
  51         spin_unlock_irq(&task->sighand->siglock);
  52
  53         return ret;
  54 }
  55
  56 static void ptrace_unfreeze_traced(struct task_struct *task)
  57 {
  58         if (task->state != __TASK_TRACED)
  59                 return;
  60
  61         WARN_ON(!task->ptrace || task->parent != current);
  62
  63         spin_lock_irq(&task->sighand->siglock);
  64         if (__fatal_signal_pending(task))
  65                 wake_up_state(task, __TASK_TRACED);
  66         else
  67                 task->state = TASK_TRACED;
  68         spin_unlock_irq(&task->sighand->siglock);
  69 }
  70
  71 /**
  72  * __ptrace_unlink - unlink ptracee and restore its execution state
  73  * @child: ptracee to be unlinked
  74  *
  75  * Remove @child from the ptrace list, move it back to the original parent,
  76  * and restore the execution state so that it conforms to the group stop
  77  * state.
  78  *
  79  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  80  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  81  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  82  * If the ptracer is exiting, the ptracee can be in any state.
  83  *
  84  * After detach, the ptracee should be in a state which conforms to the
  85  * group stop.  If the group is stopped or in the process of stopping, the
  86  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  87  * up from TASK_TRACED.
  88  *
  89  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  90  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  91  * to but in the opposite direction of what happens while attaching to a
  92  * stopped task.  However, in this direction, the intermediate RUNNING
  93  * state is not hidden even from the current ptracer and if it immediately
  94  * re-attaches and performs a WNOHANG wait(2), it may fail.
  95  *
  96  * CONTEXT:
  97  * write_lock_irq(tasklist_lock)
  98  */
  99 void __ptrace_unlink(struct task_struct *child)
 100 {
 101         BUG_ON(!child->ptrace);
 102
 103         child->ptrace = 0;
 104         child->parent = child->real_parent;
 105         list_del_init(&child->ptrace_entry);
 106
 107         spin_lock(&child->sighand->siglock);
 108
 109         /*
 110          * Reinstate GROUP_STOP_PENDING if group stop is in effect and
 111          * @child isn't dead.
 112          */
 113         if (!(child->flags & PF_EXITING) &&
 114             (child->signal->flags & SIGNAL_STOP_STOPPED ||
 115              child->signal->group_stop_count))
 116                 child->group_stop |= GROUP_STOP_PENDING;
 117
 118         /*
 119          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
 120          * @child in the butt.  Note that @resume should be used iff @child
 121          * is in TASK_TRACED; otherwise, we might unduly disrupt
 122          * TASK_KILLABLE sleeps.
 123          */
 124         if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
 125                 ptrace_signal_wake_up(child, true);
 126
 127         spin_unlock(&child->sighand->siglock);
 128 }
 129
 130 /*
 131  * Check that we have indeed attached to the thing..
 132  */
 133 int ptrace_check_attach(struct task_struct *child, int kill)
 134 {
 135         int ret = -ESRCH;
 136
 137         /*
 138          * We take the read lock around doing both checks to close a
 139          * possible race where someone else was tracing our child and
 140          * detached between these two checks.  After this locked check,
 141          * we are sure that this is our traced child and that can only
 142          * be changed by us so it's not changing right after this.
 143          */
 144         read_lock(&tasklist_lock);
 145         if (child->ptrace && child->parent == current) {
 146                 WARN_ON(child->state == __TASK_TRACED);
 147                 /*
 148                  * child->sighand can't be NULL, release_task()
 149                  * does ptrace_unlink() before __exit_signal().
 150                  */
 151                 if (kill || ptrace_freeze_traced(child))
 152                         ret = 0;
 153         }
 154         read_unlock(&tasklist_lock);
 155
 156         if (!ret && !kill) {
 157                 if (!wait_task_inactive(child, __TASK_TRACED)) {
 158                         /*
 159                          * This can only happen if may_ptrace_stop() fails and
 160                          * ptrace_stop() changes ->state back to TASK_RUNNING,
 161                          * so we should not worry about leaking __TASK_TRACED.
 162                          */
 163                         WARN_ON(child->state == __TASK_TRACED);
 164                         ret = -ESRCH;
 165                 }
 166         }
 167
 168         return ret;
 169 }
 170
 171 int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 172 {
 173         const struct cred *cred = current_cred(), *tcred;
 174
 175         /* May we inspect the given task?
 176          * This check is used both for attaching with ptrace
 177          * and for allowing access to sensitive information in /proc.
 178          *
 179          * ptrace_attach denies several cases that /proc allows
 180          * because setting up the necessary parent/child relationship
 181          * or halting the specified task is impossible.
 182          */
 183         int dumpable = 0;
 184         /* Don't let security modules deny introspection */
 185         if (task == current)
 186                 return 0;
 187         rcu_read_lock();
 188         tcred = __task_cred(task);
 189         if (cred->user->user_ns == tcred->user->user_ns &&
 190             (cred->uid == tcred->euid &&
 191              cred->uid == tcred->suid &&
 192              cred->uid == tcred->uid  &&
 193              cred->gid == tcred->egid &&
 194              cred->gid == tcred->sgid &&
 195              cred->gid == tcred->gid))
 196                 goto ok;
 197         if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
 198                 goto ok;
 199         rcu_read_unlock();
 200         return -EPERM;
 201 ok:
 202         rcu_read_unlock();
 203         smp_rmb();
 204         if (task->mm)
 205                 dumpable = get_dumpable(task->mm);
 206         if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
 207                 return -EPERM;
 208
 209         return security_ptrace_access_check(task, mode);
 210 }
 211
 212 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 213 {
 214         int err;
 215         task_lock(task);
 216         err = __ptrace_may_access(task, mode);
 217         task_unlock(task);
 218         return !err;
 219 }
 220
 221 static int ptrace_attach(struct task_struct *task)
 222 {
 223         bool wait_trap = false;
 224         int retval;
 225
 226         audit_ptrace(task);
 227
 228         retval = -EPERM;
 229         if (unlikely(task->flags & PF_KTHREAD))
 230                 goto out;
 231         if (same_thread_group(task, current))
 232                 goto out;
 233
 234         /*
 235          * Protect exec's credential calculations against our interference;
 236          * interference; SUID, SGID and LSM creds get determined differently
 237          * under ptrace.
 238          */
 239         retval = -ERESTARTNOINTR;
 240         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 241                 goto out;
 242
 243         task_lock(task);
 244         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 245         task_unlock(task);
 246         if (retval)
 247                 goto unlock_creds;
 248
 249         write_lock_irq(&tasklist_lock);
 250         retval = -EPERM;
 251         if (unlikely(task->exit_state))
 252                 goto unlock_tasklist;
 253         if (task->ptrace)
 254                 goto unlock_tasklist;
 255
 256         task->ptrace = PT_PTRACED;
 257         if (task_ns_capable(task, CAP_SYS_PTRACE))
 258                 task->ptrace |= PT_PTRACE_CAP;
 259
 260         __ptrace_link(task, current);
 261         send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 262
 263         spin_lock(&task->sighand->siglock);
 264
 265         /*
 266          * If the task is already STOPPED, set GROUP_STOP_PENDING and
 267          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 268          * will be cleared if the child completes the transition or any
 269          * event which clears the group stop states happens.  We'll wait
 270          * for the transition to complete before returning from this
 271          * function.
 272          *
 273          * This hides STOPPED -> RUNNING -> TRACED transition from the
 274          * attaching thread but a different thread in the same group can
 275          * still observe the transient RUNNING state.  IOW, if another
 276          * thread's WNOHANG wait(2) on the stopped tracee races against
 277          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 278          *
 279          * The following task_is_stopped() test is safe as both transitions
 280          * in and out of STOPPED are protected by siglock.
 281          */
 282         if (task_is_stopped(task)) {
 283                 task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
 284                 signal_wake_up_state(task, __TASK_STOPPED);
 285                 wait_trap = true;
 286         }
 287
 288         spin_unlock(&task->sighand->siglock);
 289
 290         retval = 0;
 291 unlock_tasklist:
 292         write_unlock_irq(&tasklist_lock);
 293 unlock_creds:
 294         mutex_unlock(&task->signal->cred_guard_mutex);
 295 out:
 296         if (wait_trap)
 297                 wait_event(current->signal->wait_chldexit,
 298                            !(task->group_stop & GROUP_STOP_TRAPPING));
 299         return retval;
 300 }
 301
 302 /**
 303  * ptrace_traceme  --  helper for PTRACE_TRACEME
 304  *
 305  * Performs checks and sets PT_PTRACED.
 306  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 307  */
 308 static int ptrace_traceme(void)
 309 {
 310         int ret = -EPERM;
 311
 312         write_lock_irq(&tasklist_lock);
 313         /* Are we already being traced? */
 314         if (!current->ptrace) {
 315                 ret = security_ptrace_traceme(current->parent);
 316                 /*
 317                  * Check PF_EXITING to ensure ->real_parent has not passed
 318                  * exit_ptrace(). Otherwise we don't report the error but
 319                  * pretend ->real_parent untraces us right after return.
 320                  */
 321                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 322                         current->ptrace = PT_PTRACED;
 323                         __ptrace_link(current, current->real_parent);
 324                 }
 325         }
 326         write_unlock_irq(&tasklist_lock);
 327
 328         return ret;
 329 }
 330
 331 /*
 332  * Called with irqs disabled, returns true if childs should reap themselves.
 333  */
 334 static int ignoring_children(struct sighand_struct *sigh)
 335 {
 336         int ret;
 337         spin_lock(&sigh->siglock);
 338         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 339               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 340         spin_unlock(&sigh->siglock);
 341         return ret;
 342 }
 343
 344 /*
 345  * Called with tasklist_lock held for writing.
 346  * Unlink a traced task, and clean it up if it was a traced zombie.
 347  * Return true if it needs to be reaped with release_task().
 348  * (We can't call release_task() here because we already hold tasklist_lock.)
 349  *
 350  * If it's a zombie, our attachedness prevented normal parent notification
 351  * or self-reaping.  Do notification now if it would have happened earlier.
 352  * If it should reap itself, return true.
 353  *
 354  * If it's our own child, there is no notification to do. But if our normal
 355  * children self-reap, then this child was prevented by ptrace and we must
 356  * reap it now, in that case we must also wake up sub-threads sleeping in
 357  * do_wait().
 358  */
 359 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 360 {
 361         __ptrace_unlink(p);
 362
 363         if (p->exit_state == EXIT_ZOMBIE) {
 364                 if (!task_detached(p) && thread_group_empty(p)) {
 365                         if (!same_thread_group(p->real_parent, tracer))
 366                                 do_notify_parent(p, p->exit_signal);
 367                         else if (ignoring_children(tracer->sighand)) {
 368                                 __wake_up_parent(p, tracer);
 369                                 p->exit_signal = -1;
 370                         }
 371                 }
 372                 if (task_detached(p)) {
 373                         /* Mark it as in the process of being reaped. */
 374                         p->exit_state = EXIT_DEAD;
 375                         return true;
 376                 }
 377         }
 378
 379         return false;
 380 }
 381
 382 static int ptrace_detach(struct task_struct *child, unsigned int data)
 383 {
 384         bool dead = false;
 385
 386         if (!valid_signal(data))
 387                 return -EIO;
 388
 389         /* Architecture-specific hardware disable .. */
 390         ptrace_disable(child);
 391         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 392
 393         write_lock_irq(&tasklist_lock);
 394         /*
 395          * This child can be already killed. Make sure de_thread() or
 396          * our sub-thread doing do_wait() didn't do release_task() yet.
 397          */
 398         if (child->ptrace) {
 399                 child->exit_code = data;
 400                 dead = __ptrace_detach(current, child);
 401         }
 402         write_unlock_irq(&tasklist_lock);
 403
 404         if (unlikely(dead))
 405                 release_task(child);
 406
 407         return 0;
 408 }
 409
 410 /*
 411  * Detach all tasks we were using ptrace on. Called with tasklist held
 412  * for writing, and returns with it held too. But note it can release
 413  * and reacquire the lock.
 414  */
 415 void exit_ptrace(struct task_struct *tracer)
 416         __releases(&tasklist_lock)
 417         __acquires(&tasklist_lock)
 418 {
 419         struct task_struct *p, *n;
 420         LIST_HEAD(ptrace_dead);
 421
 422         if (likely(list_empty(&tracer->ptraced)))
 423                 return;
 424
 425         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 426                 if (__ptrace_detach(tracer, p))
 427                         list_add(&p->ptrace_entry, &ptrace_dead);
 428         }
 429
 430         write_unlock_irq(&tasklist_lock);
 431         BUG_ON(!list_empty(&tracer->ptraced));
 432
 433         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 434                 list_del_init(&p->ptrace_entry);
 435                 release_task(p);
 436         }
 437
 438         write_lock_irq(&tasklist_lock);
 439 }
 440
 441 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 442 {
 443         int copied = 0;
 444
 445         while (len > 0) {
 446                 char buf[128];
 447                 int this_len, retval;
 448
 449                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 450                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 451                 if (!retval) {
 452                         if (copied)
 453                                 break;
 454                         return -EIO;
 455                 }
 456                 if (copy_to_user(dst, buf, retval))
 457                         return -EFAULT;
 458                 copied += retval;
 459                 src += retval;
 460                 dst += retval;
 461                 len -= retval;
 462         }
 463         return copied;
 464 }
 465
 466 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 467 {
 468         int copied = 0;
 469
 470         while (len > 0) {
 471                 char buf[128];
 472                 int this_len, retval;
 473
 474                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 475                 if (copy_from_user(buf, src, this_len))
 476                         return -EFAULT;
 477                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 478                 if (!retval) {
 479                         if (copied)
 480                                 break;
 481                         return -EIO;
 482                 }
 483                 copied += retval;
 484                 src += retval;
 485                 dst += retval;
 486                 len -= retval;
 487         }
 488         return copied;
 489 }
 490
 491 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 492 {
 493         child->ptrace &= ~PT_TRACE_MASK;
 494
 495         if (data & PTRACE_O_TRACESYSGOOD)
 496                 child->ptrace |= PT_TRACESYSGOOD;
 497
 498         if (data & PTRACE_O_TRACEFORK)
 499                 child->ptrace |= PT_TRACE_FORK;
 500
 501         if (data & PTRACE_O_TRACEVFORK)
 502                 child->ptrace |= PT_TRACE_VFORK;
 503
 504         if (data & PTRACE_O_TRACECLONE)
 505                 child->ptrace |= PT_TRACE_CLONE;
 506
 507         if (data & PTRACE_O_TRACEEXEC)
 508                 child->ptrace |= PT_TRACE_EXEC;
 509
 510         if (data & PTRACE_O_TRACEVFORKDONE)
 511                 child->ptrace |= PT_TRACE_VFORK_DONE;
 512
 513         if (data & PTRACE_O_TRACEEXIT)
 514                 child->ptrace |= PT_TRACE_EXIT;
 515
 516         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 517 }
 518
 519 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 520 {
 521         unsigned long flags;
 522         int error = -ESRCH;
 523
 524         if (lock_task_sighand(child, &flags)) {
 525                 error = -EINVAL;
 526                 if (likely(child->last_siginfo != NULL)) {
 527                         *info = *child->last_siginfo;
 528                         error = 0;
 529                 }
 530                 unlock_task_sighand(child, &flags);
 531         }
 532         return error;
 533 }
 534
 535 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 536 {
 537         unsigned long flags;
 538         int error = -ESRCH;
 539
 540         if (lock_task_sighand(child, &flags)) {
 541                 error = -EINVAL;
 542                 if (likely(child->last_siginfo != NULL)) {
 543                         *child->last_siginfo = *info;
 544                         error = 0;
 545                 }
 546                 unlock_task_sighand(child, &flags);
 547         }
 548         return error;
 549 }
 550
 551
 552 #ifdef PTRACE_SINGLESTEP
 553 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 554 #else
 555 #define is_singlestep(request)          0
 556 #endif
 557
 558 #ifdef PTRACE_SINGLEBLOCK
 559 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 560 #else
 561 #define is_singleblock(request)         0
 562 #endif
 563
 564 #ifdef PTRACE_SYSEMU
 565 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 566 #else
 567 #define is_sysemu_singlestep(request)   0
 568 #endif
 569
 570 static int ptrace_resume(struct task_struct *child, long request,
 571                          unsigned long data)
 572 {
 573         if (!valid_signal(data))
 574                 return -EIO;
 575
 576         if (request == PTRACE_SYSCALL)
 577                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 578         else
 579                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 580
 581 #ifdef TIF_SYSCALL_EMU
 582         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 583                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 584         else
 585                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 586 #endif
 587
 588         if (is_singleblock(request)) {
 589                 if (unlikely(!arch_has_block_step()))
 590                         return -EIO;
 591                 user_enable_block_step(child);
 592         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 593                 if (unlikely(!arch_has_single_step()))
 594                         return -EIO;
 595                 user_enable_single_step(child);
 596         } else {
 597                 user_disable_single_step(child);
 598         }
 599
 600         child->exit_code = data;
 601         wake_up_state(child, __TASK_TRACED);
 602
 603         return 0;
 604 }
 605
 606 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 607
 608 static const struct user_regset *
 609 find_regset(const struct user_regset_view *view, unsigned int type)
 610 {
 611         const struct user_regset *regset;
 612         int n;
 613
 614         for (n = 0; n < view->n; ++n) {
 615                 regset = view->regsets + n;
 616                 if (regset->core_note_type == type)
 617                         return regset;
 618         }
 619
 620         return NULL;
 621 }
 622
 623 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 624                          struct iovec *kiov)
 625 {
 626         const struct user_regset_view *view = task_user_regset_view(task);
 627         const struct user_regset *regset = find_regset(view, type);
 628         int regset_no;
 629
 630         if (!regset || (kiov->iov_len % regset->size) != 0)
 631                 return -EINVAL;
 632
 633         regset_no = regset - view->regsets;
 634         kiov->iov_len = min(kiov->iov_len,
 635                             (__kernel_size_t) (regset->n * regset->size));
 636
 637         if (req == PTRACE_GETREGSET)
 638                 return copy_regset_to_user(task, view, regset_no, 0,
 639                                            kiov->iov_len, kiov->iov_base);
 640         else
 641                 return copy_regset_from_user(task, view, regset_no, 0,
 642                                              kiov->iov_len, kiov->iov_base);
 643 }
 644
 645 #endif
 646
 647 int ptrace_request(struct task_struct *child, long request,
 648                    unsigned long addr, unsigned long data)
 649 {
 650         int ret = -EIO;
 651         siginfo_t siginfo;
 652         void __user *datavp = (void __user *) data;
 653         unsigned long __user *datalp = datavp;
 654
 655         switch (request) {
 656         case PTRACE_PEEKTEXT:
 657         case PTRACE_PEEKDATA:
 658                 return generic_ptrace_peekdata(child, addr, data);
 659         case PTRACE_POKETEXT:
 660         case PTRACE_POKEDATA:
 661                 return generic_ptrace_pokedata(child, addr, data);
 662
 663 #ifdef PTRACE_OLDSETOPTIONS
 664         case PTRACE_OLDSETOPTIONS:
 665 #endif
 666         case PTRACE_SETOPTIONS:
 667                 ret = ptrace_setoptions(child, data);
 668                 break;
 669         case PTRACE_GETEVENTMSG:
 670                 ret = put_user(child->ptrace_message, datalp);
 671                 break;
 672
 673         case PTRACE_GETSIGINFO:
 674                 ret = ptrace_getsiginfo(child, &siginfo);
 675                 if (!ret)
 676                         ret = copy_siginfo_to_user(datavp, &siginfo);
 677                 break;
 678
 679         case PTRACE_SETSIGINFO:
 680                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 681                         ret = -EFAULT;
 682                 else
 683                         ret = ptrace_setsiginfo(child, &siginfo);
 684                 break;
 685
 686         case PTRACE_DETACH:      /* detach a process that was attached. */
 687                 ret = ptrace_detach(child, data);
 688                 break;
 689
 690 #ifdef CONFIG_BINFMT_ELF_FDPIC
 691         case PTRACE_GETFDPIC: {
 692                 struct mm_struct *mm = get_task_mm(child);
 693                 unsigned long tmp = 0;
 694
 695                 ret = -ESRCH;
 696                 if (!mm)
 697                         break;
 698
 699                 switch (addr) {
 700                 case PTRACE_GETFDPIC_EXEC:
 701                         tmp = mm->context.exec_fdpic_loadmap;
 702                         break;
 703                 case PTRACE_GETFDPIC_INTERP:
 704                         tmp = mm->context.interp_fdpic_loadmap;
 705                         break;
 706                 default:
 707                         break;
 708                 }
 709                 mmput(mm);
 710
 711                 ret = put_user(tmp, datalp);
 712                 break;
 713         }
 714 #endif
 715
 716 #ifdef PTRACE_SINGLESTEP
 717         case PTRACE_SINGLESTEP:
 718 #endif
 719 #ifdef PTRACE_SINGLEBLOCK
 720         case PTRACE_SINGLEBLOCK:
 721 #endif
 722 #ifdef PTRACE_SYSEMU
 723         case PTRACE_SYSEMU:
 724         case PTRACE_SYSEMU_SINGLESTEP:
 725 #endif
 726         case PTRACE_SYSCALL:
 727         case PTRACE_CONT:
 728                 return ptrace_resume(child, request, data);
 729
 730         case PTRACE_KILL:
 731                 if (child->exit_state)  /* already dead */
 732                         return 0;
 733                 return ptrace_resume(child, request, SIGKILL);
 734
 735 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 736         case PTRACE_GETREGSET:
 737         case PTRACE_SETREGSET:
 738         {
 739                 struct iovec kiov;
 740                 struct iovec __user *uiov = datavp;
 741
 742                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 743                         return -EFAULT;
 744
 745                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 746                     __get_user(kiov.iov_len, &uiov->iov_len))
 747                         return -EFAULT;
 748
 749                 ret = ptrace_regset(child, request, addr, &kiov);
 750                 if (!ret)
 751                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 752                 break;
 753         }
 754 #endif
 755         default:
 756                 break;
 757         }
 758
 759         return ret;
 760 }
 761
 762 static struct task_struct *ptrace_get_task_struct(pid_t pid)
 763 {
 764         struct task_struct *child;
 765
 766         rcu_read_lock();
 767         child = find_task_by_vpid(pid);
 768         if (child)
 769                 get_task_struct(child);
 770         rcu_read_unlock();
 771
 772         if (!child)
 773                 return ERR_PTR(-ESRCH);
 774         return child;
 775 }
 776
 777 #ifndef arch_ptrace_attach
 778 #define arch_ptrace_attach(child)       do { } while (0)
 779 #endif
 780
 781 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 782                 unsigned long, data)
 783 {
 784         struct task_struct *child;
 785         long ret;
 786
 787         if (request == PTRACE_TRACEME) {
 788                 ret = ptrace_traceme();
 789                 if (!ret)
 790                         arch_ptrace_attach(current);
 791                 goto out;
 792         }
 793
 794         child = ptrace_get_task_struct(pid);
 795         if (IS_ERR(child)) {
 796                 ret = PTR_ERR(child);
 797                 goto out;
 798         }
 799
 800         if (request == PTRACE_ATTACH) {
 801                 ret = ptrace_attach(child);
 802                 /*
 803                  * Some architectures need to do book-keeping after
 804                  * a ptrace attach.
 805                  */
 806                 if (!ret)
 807                         arch_ptrace_attach(child);
 808                 goto out_put_task_struct;
 809         }
 810
 811         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 812         if (ret < 0)
 813                 goto out_put_task_struct;
 814
 815         ret = arch_ptrace(child, request, addr, data);
 816         if (ret || request != PTRACE_DETACH)
 817                 ptrace_unfreeze_traced(child);
 818
 819  out_put_task_struct:
 820         put_task_struct(child);
 821  out:
 822         return ret;
 823 }
 824
 825 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 826                             unsigned long data)
 827 {
 828         unsigned long tmp;
 829         int copied;
 830
 831         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 832         if (copied != sizeof(tmp))
 833                 return -EIO;
 834         return put_user(tmp, (unsigned long __user *)data);
 835 }
 836
 837 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 838                             unsigned long data)
 839 {
 840         int copied;
 841
 842         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 843         return (copied == sizeof(data)) ? 0 : -EIO;
 844 }
 845
 846 #if defined CONFIG_COMPAT
 847 #include <linux/compat.h>
 848
 849 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 850                           compat_ulong_t addr, compat_ulong_t data)
 851 {
 852         compat_ulong_t __user *datap = compat_ptr(data);
 853         compat_ulong_t word;
 854         siginfo_t siginfo;
 855         int ret;
 856
 857         switch (request) {
 858         case PTRACE_PEEKTEXT:
 859         case PTRACE_PEEKDATA:
 860                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 861                 if (ret != sizeof(word))
 862                         ret = -EIO;
 863                 else
 864                         ret = put_user(word, datap);
 865                 break;
 866
 867         case PTRACE_POKETEXT:
 868         case PTRACE_POKEDATA:
 869                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 870                 ret = (ret != sizeof(data) ? -EIO : 0);
 871                 break;
 872
 873         case PTRACE_GETEVENTMSG:
 874                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 875                 break;
 876
 877         case PTRACE_GETSIGINFO:
 878                 ret = ptrace_getsiginfo(child, &siginfo);
 879                 if (!ret)
 880                         ret = copy_siginfo_to_user32(
 881                                 (struct compat_siginfo __user *) datap,
 882                                 &siginfo);
 883                 break;
 884
 885         case PTRACE_SETSIGINFO:
 886                 memset(&siginfo, 0, sizeof siginfo);
 887                 if (copy_siginfo_from_user32(
 888                             &siginfo, (struct compat_siginfo __user *) datap))
 889                         ret = -EFAULT;
 890                 else
 891                         ret = ptrace_setsiginfo(child, &siginfo);
 892                 break;
 893 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 894         case PTRACE_GETREGSET:
 895         case PTRACE_SETREGSET:
 896         {
 897                 struct iovec kiov;
 898                 struct compat_iovec __user *uiov =
 899                         (struct compat_iovec __user *) datap;
 900                 compat_uptr_t ptr;
 901                 compat_size_t len;
 902
 903                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 904                         return -EFAULT;
 905
 906                 if (__get_user(ptr, &uiov->iov_base) ||
 907                     __get_user(len, &uiov->iov_len))
 908                         return -EFAULT;
 909
 910                 kiov.iov_base = compat_ptr(ptr);
 911                 kiov.iov_len = len;
 912
 913                 ret = ptrace_regset(child, request, addr, &kiov);
 914                 if (!ret)
 915                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 916                 break;
 917         }
 918 #endif
 919
 920         default:
 921                 ret = ptrace_request(child, request, addr, data);
 922         }
 923
 924         return ret;
 925 }
 926
 927 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 928                                   compat_long_t addr, compat_long_t data)
 929 {
 930         struct task_struct *child;
 931         long ret;
 932
 933         if (request == PTRACE_TRACEME) {
 934                 ret = ptrace_traceme();
 935                 goto out;
 936         }
 937
 938         child = ptrace_get_task_struct(pid);
 939         if (IS_ERR(child)) {
 940                 ret = PTR_ERR(child);
 941                 goto out;
 942         }
 943
 944         if (request == PTRACE_ATTACH) {
 945                 ret = ptrace_attach(child);
 946                 /*
 947                  * Some architectures need to do book-keeping after
 948                  * a ptrace attach.
 949                  */
 950                 if (!ret)
 951                         arch_ptrace_attach(child);
 952                 goto out_put_task_struct;
 953         }
 954
 955         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 956         if (!ret) {
 957                 ret = compat_arch_ptrace(child, request, addr, data);
 958                 if (ret || request != PTRACE_DETACH)
 959                         ptrace_unfreeze_traced(child);
 960         }
 961
 962  out_put_task_struct:
 963         put_task_struct(child);
 964  out:
 965         return ret;
 966 }
 967 #endif  /* CONFIG_COMPAT */
 968
 969 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 970 int ptrace_get_breakpoints(struct task_struct *tsk)
 971 {
 972         if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
 973                 return 0;
 974
 975         return -1;
 976 }
 977
 978 void ptrace_put_breakpoints(struct task_struct *tsk)
 979 {
 980         if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
 981                 flush_ptrace_hw_breakpoint(tsk);
 982 }
 983 #endif /* CONFIG_HAVE_HW_BREAKPOINT */