kernel/ptrace.c

   1 /*
   2  * linux/kernel/ptrace.c
   3  *
   4  * (C) Copyright 1999 Linus Torvalds
   5  *
   6  * Common interfaces for "ptrace()" which we do not want
   7  * to continually duplicate across every architecture.
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/errno.h>
  14 #include <linux/mm.h>
  15 #include <linux/highmem.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/security.h>
  19 #include <linux/signal.h>
  20 #include <linux/audit.h>
  21 #include <linux/pid_namespace.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/regset.h>
  25
  26
  27 /*
  28  * ptrace a task: make the debugger its new parent and
  29  * move it to the ptrace list.
  30  *
  31  * Must be called with the tasklist lock write-held.
  32  */
  33 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  34 {
  35         BUG_ON(!list_empty(&child->ptrace_entry));
  36         list_add(&child->ptrace_entry, &new_parent->ptraced);
  37         child->parent = new_parent;
  38 }
  39
  40 /**
  41  * __ptrace_unlink - unlink ptracee and restore its execution state
  42  * @child: ptracee to be unlinked
  43  *
  44  * Remove @child from the ptrace list, move it back to the original parent,
  45  * and restore the execution state so that it conforms to the group stop
  46  * state.
  47  *
  48  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  49  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  50  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  51  * If the ptracer is exiting, the ptracee can be in any state.
  52  *
  53  * After detach, the ptracee should be in a state which conforms to the
  54  * group stop.  If the group is stopped or in the process of stopping, the
  55  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  56  * up from TASK_TRACED.
  57  *
  58  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  59  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  60  * to but in the opposite direction of what happens while attaching to a
  61  * stopped task.  However, in this direction, the intermediate RUNNING
  62  * state is not hidden even from the current ptracer and if it immediately
  63  * re-attaches and performs a WNOHANG wait(2), it may fail.
  64  *
  65  * CONTEXT:
  66  * write_lock_irq(tasklist_lock)
  67  */
  68 void __ptrace_unlink(struct task_struct *child)
  69 {
  70         BUG_ON(!child->ptrace);
  71
  72         child->ptrace = 0;
  73         child->parent = child->real_parent;
  74         list_del_init(&child->ptrace_entry);
  75
  76         spin_lock(&child->sighand->siglock);
  77
  78         /*
  79          * Reinstate GROUP_STOP_PENDING if group stop is in effect and
  80          * @child isn't dead.
  81          */
  82         if (!(child->flags & PF_EXITING) &&
  83             (child->signal->flags & SIGNAL_STOP_STOPPED ||
  84              child->signal->group_stop_count))
  85                 child->group_stop |= GROUP_STOP_PENDING;
  86
  87         /*
  88          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
  89          * @child in the butt.  Note that @resume should be used iff @child
  90          * is in TASK_TRACED; otherwise, we might unduly disrupt
  91          * TASK_KILLABLE sleeps.
  92          */
  93         if (child->group_stop & GROUP_STOP_PENDING || task_is_traced(child))
  94                 signal_wake_up(child, task_is_traced(child));
  95
  96         spin_unlock(&child->sighand->siglock);
  97 }
  98
  99 /*
 100  * Check that we have indeed attached to the thing..
 101  */
 102 int ptrace_check_attach(struct task_struct *child, int kill)
 103 {
 104         int ret = -ESRCH;
 105
 106         /*
 107          * We take the read lock around doing both checks to close a
 108          * possible race where someone else was tracing our child and
 109          * detached between these two checks.  After this locked check,
 110          * we are sure that this is our traced child and that can only
 111          * be changed by us so it's not changing right after this.
 112          */
 113         read_lock(&tasklist_lock);
 114         if ((child->ptrace & PT_PTRACED) && child->parent == current) {
 115                 /*
 116                  * child->sighand can't be NULL, release_task()
 117                  * does ptrace_unlink() before __exit_signal().
 118                  */
 119                 spin_lock_irq(&child->sighand->siglock);
 120                 WARN_ON_ONCE(task_is_stopped(child));
 121                 if (task_is_traced(child) || kill)
 122                         ret = 0;
 123                 spin_unlock_irq(&child->sighand->siglock);
 124         }
 125         read_unlock(&tasklist_lock);
 126
 127         if (!ret && !kill)
 128                 ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 129
 130         /* All systems go.. */
 131         return ret;
 132 }
 133
 134 int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 135 {
 136         const struct cred *cred = current_cred(), *tcred;
 137
 138         /* May we inspect the given task?
 139          * This check is used both for attaching with ptrace
 140          * and for allowing access to sensitive information in /proc.
 141          *
 142          * ptrace_attach denies several cases that /proc allows
 143          * because setting up the necessary parent/child relationship
 144          * or halting the specified task is impossible.
 145          */
 146         int dumpable = 0;
 147         /* Don't let security modules deny introspection */
 148         if (task == current)
 149                 return 0;
 150         rcu_read_lock();
 151         tcred = __task_cred(task);
 152         if (cred->user->user_ns == tcred->user->user_ns &&
 153             (cred->uid == tcred->euid &&
 154              cred->uid == tcred->suid &&
 155              cred->uid == tcred->uid  &&
 156              cred->gid == tcred->egid &&
 157              cred->gid == tcred->sgid &&
 158              cred->gid == tcred->gid))
 159                 goto ok;
 160         if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
 161                 goto ok;
 162         rcu_read_unlock();
 163         return -EPERM;
 164 ok:
 165         rcu_read_unlock();
 166         smp_rmb();
 167         if (task->mm)
 168                 dumpable = get_dumpable(task->mm);
 169         if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
 170                 return -EPERM;
 171
 172         return security_ptrace_access_check(task, mode);
 173 }
 174
 175 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 176 {
 177         int err;
 178         task_lock(task);
 179         err = __ptrace_may_access(task, mode);
 180         task_unlock(task);
 181         return !err;
 182 }
 183
 184 static int ptrace_attach(struct task_struct *task)
 185 {
 186         bool wait_trap = false;
 187         int retval;
 188
 189         audit_ptrace(task);
 190
 191         retval = -EPERM;
 192         if (unlikely(task->flags & PF_KTHREAD))
 193                 goto out;
 194         if (same_thread_group(task, current))
 195                 goto out;
 196
 197         /*
 198          * Protect exec's credential calculations against our interference;
 199          * interference; SUID, SGID and LSM creds get determined differently
 200          * under ptrace.
 201          */
 202         retval = -ERESTARTNOINTR;
 203         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 204                 goto out;
 205
 206         task_lock(task);
 207         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 208         task_unlock(task);
 209         if (retval)
 210                 goto unlock_creds;
 211
 212         write_lock_irq(&tasklist_lock);
 213         retval = -EPERM;
 214         if (unlikely(task->exit_state))
 215                 goto unlock_tasklist;
 216         if (task->ptrace)
 217                 goto unlock_tasklist;
 218
 219         task->ptrace = PT_PTRACED;
 220         if (task_ns_capable(task, CAP_SYS_PTRACE))
 221                 task->ptrace |= PT_PTRACE_CAP;
 222
 223         __ptrace_link(task, current);
 224         send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 225
 226         spin_lock(&task->sighand->siglock);
 227
 228         /*
 229          * If the task is already STOPPED, set GROUP_STOP_PENDING and
 230          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 231          * will be cleared if the child completes the transition or any
 232          * event which clears the group stop states happens.  We'll wait
 233          * for the transition to complete before returning from this
 234          * function.
 235          *
 236          * This hides STOPPED -> RUNNING -> TRACED transition from the
 237          * attaching thread but a different thread in the same group can
 238          * still observe the transient RUNNING state.  IOW, if another
 239          * thread's WNOHANG wait(2) on the stopped tracee races against
 240          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 241          *
 242          * The following task_is_stopped() test is safe as both transitions
 243          * in and out of STOPPED are protected by siglock.
 244          */
 245         if (task_is_stopped(task)) {
 246                 task->group_stop |= GROUP_STOP_PENDING | GROUP_STOP_TRAPPING;
 247                 signal_wake_up(task, 1);
 248                 wait_trap = true;
 249         }
 250
 251         spin_unlock(&task->sighand->siglock);
 252
 253         retval = 0;
 254 unlock_tasklist:
 255         write_unlock_irq(&tasklist_lock);
 256 unlock_creds:
 257         mutex_unlock(&task->signal->cred_guard_mutex);
 258 out:
 259         if (wait_trap)
 260                 wait_event(current->signal->wait_chldexit,
 261                            !(task->group_stop & GROUP_STOP_TRAPPING));
 262         return retval;
 263 }
 264
 265 /**
 266  * ptrace_traceme  --  helper for PTRACE_TRACEME
 267  *
 268  * Performs checks and sets PT_PTRACED.
 269  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 270  */
 271 static int ptrace_traceme(void)
 272 {
 273         int ret = -EPERM;
 274
 275         write_lock_irq(&tasklist_lock);
 276         /* Are we already being traced? */
 277         if (!current->ptrace) {
 278                 ret = security_ptrace_traceme(current->parent);
 279                 /*
 280                  * Check PF_EXITING to ensure ->real_parent has not passed
 281                  * exit_ptrace(). Otherwise we don't report the error but
 282                  * pretend ->real_parent untraces us right after return.
 283                  */
 284                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 285                         current->ptrace = PT_PTRACED;
 286                         __ptrace_link(current, current->real_parent);
 287                 }
 288         }
 289         write_unlock_irq(&tasklist_lock);
 290
 291         return ret;
 292 }
 293
 294 /*
 295  * Called with irqs disabled, returns true if childs should reap themselves.
 296  */
 297 static int ignoring_children(struct sighand_struct *sigh)
 298 {
 299         int ret;
 300         spin_lock(&sigh->siglock);
 301         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 302               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 303         spin_unlock(&sigh->siglock);
 304         return ret;
 305 }
 306
 307 /*
 308  * Called with tasklist_lock held for writing.
 309  * Unlink a traced task, and clean it up if it was a traced zombie.
 310  * Return true if it needs to be reaped with release_task().
 311  * (We can't call release_task() here because we already hold tasklist_lock.)
 312  *
 313  * If it's a zombie, our attachedness prevented normal parent notification
 314  * or self-reaping.  Do notification now if it would have happened earlier.
 315  * If it should reap itself, return true.
 316  *
 317  * If it's our own child, there is no notification to do. But if our normal
 318  * children self-reap, then this child was prevented by ptrace and we must
 319  * reap it now, in that case we must also wake up sub-threads sleeping in
 320  * do_wait().
 321  */
 322 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 323 {
 324         __ptrace_unlink(p);
 325
 326         if (p->exit_state == EXIT_ZOMBIE) {
 327                 if (!task_detached(p) && thread_group_empty(p)) {
 328                         if (!same_thread_group(p->real_parent, tracer))
 329                                 do_notify_parent(p, p->exit_signal);
 330                         else if (ignoring_children(tracer->sighand)) {
 331                                 __wake_up_parent(p, tracer);
 332                                 p->exit_signal = -1;
 333                         }
 334                 }
 335                 if (task_detached(p)) {
 336                         /* Mark it as in the process of being reaped. */
 337                         p->exit_state = EXIT_DEAD;
 338                         return true;
 339                 }
 340         }
 341
 342         return false;
 343 }
 344
 345 static int ptrace_detach(struct task_struct *child, unsigned int data)
 346 {
 347         bool dead = false;
 348
 349         if (!valid_signal(data))
 350                 return -EIO;
 351
 352         /* Architecture-specific hardware disable .. */
 353         ptrace_disable(child);
 354         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 355
 356         write_lock_irq(&tasklist_lock);
 357         /*
 358          * This child can be already killed. Make sure de_thread() or
 359          * our sub-thread doing do_wait() didn't do release_task() yet.
 360          */
 361         if (child->ptrace) {
 362                 child->exit_code = data;
 363                 dead = __ptrace_detach(current, child);
 364         }
 365         write_unlock_irq(&tasklist_lock);
 366
 367         if (unlikely(dead))
 368                 release_task(child);
 369
 370         return 0;
 371 }
 372
 373 /*
 374  * Detach all tasks we were using ptrace on. Called with tasklist held
 375  * for writing, and returns with it held too. But note it can release
 376  * and reacquire the lock.
 377  */
 378 void exit_ptrace(struct task_struct *tracer)
 379         __releases(&tasklist_lock)
 380         __acquires(&tasklist_lock)
 381 {
 382         struct task_struct *p, *n;
 383         LIST_HEAD(ptrace_dead);
 384
 385         if (likely(list_empty(&tracer->ptraced)))
 386                 return;
 387
 388         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 389                 if (__ptrace_detach(tracer, p))
 390                         list_add(&p->ptrace_entry, &ptrace_dead);
 391         }
 392
 393         write_unlock_irq(&tasklist_lock);
 394         BUG_ON(!list_empty(&tracer->ptraced));
 395
 396         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 397                 list_del_init(&p->ptrace_entry);
 398                 release_task(p);
 399         }
 400
 401         write_lock_irq(&tasklist_lock);
 402 }
 403
 404 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 405 {
 406         int copied = 0;
 407
 408         while (len > 0) {
 409                 char buf[128];
 410                 int this_len, retval;
 411
 412                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 413                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 414                 if (!retval) {
 415                         if (copied)
 416                                 break;
 417                         return -EIO;
 418                 }
 419                 if (copy_to_user(dst, buf, retval))
 420                         return -EFAULT;
 421                 copied += retval;
 422                 src += retval;
 423                 dst += retval;
 424                 len -= retval;
 425         }
 426         return copied;
 427 }
 428
 429 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 430 {
 431         int copied = 0;
 432
 433         while (len > 0) {
 434                 char buf[128];
 435                 int this_len, retval;
 436
 437                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 438                 if (copy_from_user(buf, src, this_len))
 439                         return -EFAULT;
 440                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 441                 if (!retval) {
 442                         if (copied)
 443                                 break;
 444                         return -EIO;
 445                 }
 446                 copied += retval;
 447                 src += retval;
 448                 dst += retval;
 449                 len -= retval;
 450         }
 451         return copied;
 452 }
 453
 454 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 455 {
 456         child->ptrace &= ~PT_TRACE_MASK;
 457
 458         if (data & PTRACE_O_TRACESYSGOOD)
 459                 child->ptrace |= PT_TRACESYSGOOD;
 460
 461         if (data & PTRACE_O_TRACEFORK)
 462                 child->ptrace |= PT_TRACE_FORK;
 463
 464         if (data & PTRACE_O_TRACEVFORK)
 465                 child->ptrace |= PT_TRACE_VFORK;
 466
 467         if (data & PTRACE_O_TRACECLONE)
 468                 child->ptrace |= PT_TRACE_CLONE;
 469
 470         if (data & PTRACE_O_TRACEEXEC)
 471                 child->ptrace |= PT_TRACE_EXEC;
 472
 473         if (data & PTRACE_O_TRACEVFORKDONE)
 474                 child->ptrace |= PT_TRACE_VFORK_DONE;
 475
 476         if (data & PTRACE_O_TRACEEXIT)
 477                 child->ptrace |= PT_TRACE_EXIT;
 478
 479         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 480 }
 481
 482 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 483 {
 484         unsigned long flags;
 485         int error = -ESRCH;
 486
 487         if (lock_task_sighand(child, &flags)) {
 488                 error = -EINVAL;
 489                 if (likely(child->last_siginfo != NULL)) {
 490                         *info = *child->last_siginfo;
 491                         error = 0;
 492                 }
 493                 unlock_task_sighand(child, &flags);
 494         }
 495         return error;
 496 }
 497
 498 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 499 {
 500         unsigned long flags;
 501         int error = -ESRCH;
 502
 503         if (lock_task_sighand(child, &flags)) {
 504                 error = -EINVAL;
 505                 if (likely(child->last_siginfo != NULL)) {
 506                         *child->last_siginfo = *info;
 507                         error = 0;
 508                 }
 509                 unlock_task_sighand(child, &flags);
 510         }
 511         return error;
 512 }
 513
 514
 515 #ifdef PTRACE_SINGLESTEP
 516 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 517 #else
 518 #define is_singlestep(request)          0
 519 #endif
 520
 521 #ifdef PTRACE_SINGLEBLOCK
 522 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 523 #else
 524 #define is_singleblock(request)         0
 525 #endif
 526
 527 #ifdef PTRACE_SYSEMU
 528 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 529 #else
 530 #define is_sysemu_singlestep(request)   0
 531 #endif
 532
 533 static int ptrace_resume(struct task_struct *child, long request,
 534                          unsigned long data)
 535 {
 536         if (!valid_signal(data))
 537                 return -EIO;
 538
 539         if (request == PTRACE_SYSCALL)
 540                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 541         else
 542                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 543
 544 #ifdef TIF_SYSCALL_EMU
 545         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 546                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 547         else
 548                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 549 #endif
 550
 551         if (is_singleblock(request)) {
 552                 if (unlikely(!arch_has_block_step()))
 553                         return -EIO;
 554                 user_enable_block_step(child);
 555         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 556                 if (unlikely(!arch_has_single_step()))
 557                         return -EIO;
 558                 user_enable_single_step(child);
 559         } else {
 560                 user_disable_single_step(child);
 561         }
 562
 563         child->exit_code = data;
 564         wake_up_process(child);
 565
 566         return 0;
 567 }
 568
 569 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 570
 571 static const struct user_regset *
 572 find_regset(const struct user_regset_view *view, unsigned int type)
 573 {
 574         const struct user_regset *regset;
 575         int n;
 576
 577         for (n = 0; n < view->n; ++n) {
 578                 regset = view->regsets + n;
 579                 if (regset->core_note_type == type)
 580                         return regset;
 581         }
 582
 583         return NULL;
 584 }
 585
 586 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 587                          struct iovec *kiov)
 588 {
 589         const struct user_regset_view *view = task_user_regset_view(task);
 590         const struct user_regset *regset = find_regset(view, type);
 591         int regset_no;
 592
 593         if (!regset || (kiov->iov_len % regset->size) != 0)
 594                 return -EINVAL;
 595
 596         regset_no = regset - view->regsets;
 597         kiov->iov_len = min(kiov->iov_len,
 598                             (__kernel_size_t) (regset->n * regset->size));
 599
 600         if (req == PTRACE_GETREGSET)
 601                 return copy_regset_to_user(task, view, regset_no, 0,
 602                                            kiov->iov_len, kiov->iov_base);
 603         else
 604                 return copy_regset_from_user(task, view, regset_no, 0,
 605                                              kiov->iov_len, kiov->iov_base);
 606 }
 607
 608 #endif
 609
 610 int ptrace_request(struct task_struct *child, long request,
 611                    unsigned long addr, unsigned long data)
 612 {
 613         int ret = -EIO;
 614         siginfo_t siginfo;
 615         void __user *datavp = (void __user *) data;
 616         unsigned long __user *datalp = datavp;
 617
 618         switch (request) {
 619         case PTRACE_PEEKTEXT:
 620         case PTRACE_PEEKDATA:
 621                 return generic_ptrace_peekdata(child, addr, data);
 622         case PTRACE_POKETEXT:
 623         case PTRACE_POKEDATA:
 624                 return generic_ptrace_pokedata(child, addr, data);
 625
 626 #ifdef PTRACE_OLDSETOPTIONS
 627         case PTRACE_OLDSETOPTIONS:
 628 #endif
 629         case PTRACE_SETOPTIONS:
 630                 ret = ptrace_setoptions(child, data);
 631                 break;
 632         case PTRACE_GETEVENTMSG:
 633                 ret = put_user(child->ptrace_message, datalp);
 634                 break;
 635
 636         case PTRACE_GETSIGINFO:
 637                 ret = ptrace_getsiginfo(child, &siginfo);
 638                 if (!ret)
 639                         ret = copy_siginfo_to_user(datavp, &siginfo);
 640                 break;
 641
 642         case PTRACE_SETSIGINFO:
 643                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 644                         ret = -EFAULT;
 645                 else
 646                         ret = ptrace_setsiginfo(child, &siginfo);
 647                 break;
 648
 649         case PTRACE_DETACH:      /* detach a process that was attached. */
 650                 ret = ptrace_detach(child, data);
 651                 break;
 652
 653 #ifdef CONFIG_BINFMT_ELF_FDPIC
 654         case PTRACE_GETFDPIC: {
 655                 struct mm_struct *mm = get_task_mm(child);
 656                 unsigned long tmp = 0;
 657
 658                 ret = -ESRCH;
 659                 if (!mm)
 660                         break;
 661
 662                 switch (addr) {
 663                 case PTRACE_GETFDPIC_EXEC:
 664                         tmp = mm->context.exec_fdpic_loadmap;
 665                         break;
 666                 case PTRACE_GETFDPIC_INTERP:
 667                         tmp = mm->context.interp_fdpic_loadmap;
 668                         break;
 669                 default:
 670                         break;
 671                 }
 672                 mmput(mm);
 673
 674                 ret = put_user(tmp, datalp);
 675                 break;
 676         }
 677 #endif
 678
 679 #ifdef PTRACE_SINGLESTEP
 680         case PTRACE_SINGLESTEP:
 681 #endif
 682 #ifdef PTRACE_SINGLEBLOCK
 683         case PTRACE_SINGLEBLOCK:
 684 #endif
 685 #ifdef PTRACE_SYSEMU
 686         case PTRACE_SYSEMU:
 687         case PTRACE_SYSEMU_SINGLESTEP:
 688 #endif
 689         case PTRACE_SYSCALL:
 690         case PTRACE_CONT:
 691                 return ptrace_resume(child, request, data);
 692
 693         case PTRACE_KILL:
 694                 if (child->exit_state)  /* already dead */
 695                         return 0;
 696                 return ptrace_resume(child, request, SIGKILL);
 697
 698 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 699         case PTRACE_GETREGSET:
 700         case PTRACE_SETREGSET:
 701         {
 702                 struct iovec kiov;
 703                 struct iovec __user *uiov = datavp;
 704
 705                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 706                         return -EFAULT;
 707
 708                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 709                     __get_user(kiov.iov_len, &uiov->iov_len))
 710                         return -EFAULT;
 711
 712                 ret = ptrace_regset(child, request, addr, &kiov);
 713                 if (!ret)
 714                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 715                 break;
 716         }
 717 #endif
 718         default:
 719                 break;
 720         }
 721
 722         return ret;
 723 }
 724
 725 static struct task_struct *ptrace_get_task_struct(pid_t pid)
 726 {
 727         struct task_struct *child;
 728
 729         rcu_read_lock();
 730         child = find_task_by_vpid(pid);
 731         if (child)
 732                 get_task_struct(child);
 733         rcu_read_unlock();
 734
 735         if (!child)
 736                 return ERR_PTR(-ESRCH);
 737         return child;
 738 }
 739
 740 #ifndef arch_ptrace_attach
 741 #define arch_ptrace_attach(child)       do { } while (0)
 742 #endif
 743
 744 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 745                 unsigned long, data)
 746 {
 747         struct task_struct *child;
 748         long ret;
 749
 750         if (request == PTRACE_TRACEME) {
 751                 ret = ptrace_traceme();
 752                 if (!ret)
 753                         arch_ptrace_attach(current);
 754                 goto out;
 755         }
 756
 757         child = ptrace_get_task_struct(pid);
 758         if (IS_ERR(child)) {
 759                 ret = PTR_ERR(child);
 760                 goto out;
 761         }
 762
 763         if (request == PTRACE_ATTACH) {
 764                 ret = ptrace_attach(child);
 765                 /*
 766                  * Some architectures need to do book-keeping after
 767                  * a ptrace attach.
 768                  */
 769                 if (!ret)
 770                         arch_ptrace_attach(child);
 771                 goto out_put_task_struct;
 772         }
 773
 774         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 775         if (ret < 0)
 776                 goto out_put_task_struct;
 777
 778         ret = arch_ptrace(child, request, addr, data);
 779
 780  out_put_task_struct:
 781         put_task_struct(child);
 782  out:
 783         return ret;
 784 }
 785
 786 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 787                             unsigned long data)
 788 {
 789         unsigned long tmp;
 790         int copied;
 791
 792         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 793         if (copied != sizeof(tmp))
 794                 return -EIO;
 795         return put_user(tmp, (unsigned long __user *)data);
 796 }
 797
 798 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 799                             unsigned long data)
 800 {
 801         int copied;
 802
 803         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 804         return (copied == sizeof(data)) ? 0 : -EIO;
 805 }
 806
 807 #if defined CONFIG_COMPAT
 808 #include <linux/compat.h>
 809
 810 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 811                           compat_ulong_t addr, compat_ulong_t data)
 812 {
 813         compat_ulong_t __user *datap = compat_ptr(data);
 814         compat_ulong_t word;
 815         siginfo_t siginfo;
 816         int ret;
 817
 818         switch (request) {
 819         case PTRACE_PEEKTEXT:
 820         case PTRACE_PEEKDATA:
 821                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 822                 if (ret != sizeof(word))
 823                         ret = -EIO;
 824                 else
 825                         ret = put_user(word, datap);
 826                 break;
 827
 828         case PTRACE_POKETEXT:
 829         case PTRACE_POKEDATA:
 830                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 831                 ret = (ret != sizeof(data) ? -EIO : 0);
 832                 break;
 833
 834         case PTRACE_GETEVENTMSG:
 835                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 836                 break;
 837
 838         case PTRACE_GETSIGINFO:
 839                 ret = ptrace_getsiginfo(child, &siginfo);
 840                 if (!ret)
 841                         ret = copy_siginfo_to_user32(
 842                                 (struct compat_siginfo __user *) datap,
 843                                 &siginfo);
 844                 break;
 845
 846         case PTRACE_SETSIGINFO:
 847                 memset(&siginfo, 0, sizeof siginfo);
 848                 if (copy_siginfo_from_user32(
 849                             &siginfo, (struct compat_siginfo __user *) datap))
 850                         ret = -EFAULT;
 851                 else
 852                         ret = ptrace_setsiginfo(child, &siginfo);
 853                 break;
 854 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 855         case PTRACE_GETREGSET:
 856         case PTRACE_SETREGSET:
 857         {
 858                 struct iovec kiov;
 859                 struct compat_iovec __user *uiov =
 860                         (struct compat_iovec __user *) datap;
 861                 compat_uptr_t ptr;
 862                 compat_size_t len;
 863
 864                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 865                         return -EFAULT;
 866
 867                 if (__get_user(ptr, &uiov->iov_base) ||
 868                     __get_user(len, &uiov->iov_len))
 869                         return -EFAULT;
 870
 871                 kiov.iov_base = compat_ptr(ptr);
 872                 kiov.iov_len = len;
 873
 874                 ret = ptrace_regset(child, request, addr, &kiov);
 875                 if (!ret)
 876                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 877                 break;
 878         }
 879 #endif
 880
 881         default:
 882                 ret = ptrace_request(child, request, addr, data);
 883         }
 884
 885         return ret;
 886 }
 887
 888 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 889                                   compat_long_t addr, compat_long_t data)
 890 {
 891         struct task_struct *child;
 892         long ret;
 893
 894         if (request == PTRACE_TRACEME) {
 895                 ret = ptrace_traceme();
 896                 goto out;
 897         }
 898
 899         child = ptrace_get_task_struct(pid);
 900         if (IS_ERR(child)) {
 901                 ret = PTR_ERR(child);
 902                 goto out;
 903         }
 904
 905         if (request == PTRACE_ATTACH) {
 906                 ret = ptrace_attach(child);
 907                 /*
 908                  * Some architectures need to do book-keeping after
 909                  * a ptrace attach.
 910                  */
 911                 if (!ret)
 912                         arch_ptrace_attach(child);
 913                 goto out_put_task_struct;
 914         }
 915
 916         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 917         if (!ret)
 918                 ret = compat_arch_ptrace(child, request, addr, data);
 919
 920  out_put_task_struct:
 921         put_task_struct(child);
 922  out:
 923         return ret;
 924 }
 925 #endif  /* CONFIG_COMPAT */