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/export.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 #include <linux/cn_proc.h>
  27
  28
  29 static int ptrace_trapping_sleep_fn(void *flags)
  30 {
  31         schedule();
  32         return 0;
  33 }
  34
  35 /*
  36  * ptrace a task: make the debugger its new parent and
  37  * move it to the ptrace list.
  38  *
  39  * Must be called with the tasklist lock write-held.
  40  */
  41 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  42 {
  43         BUG_ON(!list_empty(&child->ptrace_entry));
  44         list_add(&child->ptrace_entry, &new_parent->ptraced);
  45         child->parent = new_parent;
  46 }
  47
  48 /**
  49  * __ptrace_unlink - unlink ptracee and restore its execution state
  50  * @child: ptracee to be unlinked
  51  *
  52  * Remove @child from the ptrace list, move it back to the original parent,
  53  * and restore the execution state so that it conforms to the group stop
  54  * state.
  55  *
  56  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  57  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  58  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  59  * If the ptracer is exiting, the ptracee can be in any state.
  60  *
  61  * After detach, the ptracee should be in a state which conforms to the
  62  * group stop.  If the group is stopped or in the process of stopping, the
  63  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  64  * up from TASK_TRACED.
  65  *
  66  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  67  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  68  * to but in the opposite direction of what happens while attaching to a
  69  * stopped task.  However, in this direction, the intermediate RUNNING
  70  * state is not hidden even from the current ptracer and if it immediately
  71  * re-attaches and performs a WNOHANG wait(2), it may fail.
  72  *
  73  * CONTEXT:
  74  * write_lock_irq(tasklist_lock)
  75  */
  76 void __ptrace_unlink(struct task_struct *child)
  77 {
  78         BUG_ON(!child->ptrace);
  79
  80         child->ptrace = 0;
  81         child->parent = child->real_parent;
  82         list_del_init(&child->ptrace_entry);
  83
  84         spin_lock(&child->sighand->siglock);
  85
  86         /*
  87          * Clear all pending traps and TRAPPING.  TRAPPING should be
  88          * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
  89          */
  90         task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
  91         task_clear_jobctl_trapping(child);
  92
  93         /*
  94          * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
  95          * @child isn't dead.
  96          */
  97         if (!(child->flags & PF_EXITING) &&
  98             (child->signal->flags & SIGNAL_STOP_STOPPED ||
  99              child->signal->group_stop_count)) {
 100                 child->jobctl |= JOBCTL_STOP_PENDING;
 101
 102                 /*
 103                  * This is only possible if this thread was cloned by the
 104                  * traced task running in the stopped group, set the signal
 105                  * for the future reports.
 106                  * FIXME: we should change ptrace_init_task() to handle this
 107                  * case.
 108                  */
 109                 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
 110                         child->jobctl |= SIGSTOP;
 111         }
 112
 113         /*
 114          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
 115          * @child in the butt.  Note that @resume should be used iff @child
 116          * is in TASK_TRACED; otherwise, we might unduly disrupt
 117          * TASK_KILLABLE sleeps.
 118          */
 119         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
 120                 signal_wake_up(child, task_is_traced(child));
 121
 122         spin_unlock(&child->sighand->siglock);
 123 }
 124
 125 /**
 126  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
 127  * @child: ptracee to check for
 128  * @ignore_state: don't check whether @child is currently %TASK_TRACED
 129  *
 130  * Check whether @child is being ptraced by %current and ready for further
 131  * ptrace operations.  If @ignore_state is %false, @child also should be in
 132  * %TASK_TRACED state and on return the child is guaranteed to be traced
 133  * and not executing.  If @ignore_state is %true, @child can be in any
 134  * state.
 135  *
 136  * CONTEXT:
 137  * Grabs and releases tasklist_lock and @child->sighand->siglock.
 138  *
 139  * RETURNS:
 140  * 0 on success, -ESRCH if %child is not ready.
 141  */
 142 int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 143 {
 144         int ret = -ESRCH;
 145
 146         /*
 147          * We take the read lock around doing both checks to close a
 148          * possible race where someone else was tracing our child and
 149          * detached between these two checks.  After this locked check,
 150          * we are sure that this is our traced child and that can only
 151          * be changed by us so it's not changing right after this.
 152          */
 153         read_lock(&tasklist_lock);
 154         if ((child->ptrace & PT_PTRACED) && child->parent == current) {
 155                 /*
 156                  * child->sighand can't be NULL, release_task()
 157                  * does ptrace_unlink() before __exit_signal().
 158                  */
 159                 spin_lock_irq(&child->sighand->siglock);
 160                 WARN_ON_ONCE(task_is_stopped(child));
 161                 if (ignore_state || (task_is_traced(child) &&
 162                                      !(child->jobctl & JOBCTL_LISTENING)))
 163                         ret = 0;
 164                 spin_unlock_irq(&child->sighand->siglock);
 165         }
 166         read_unlock(&tasklist_lock);
 167
 168         if (!ret && !ignore_state)
 169                 ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 170
 171         /* All systems go.. */
 172         return ret;
 173 }
 174
 175 int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 176 {
 177         const struct cred *cred = current_cred(), *tcred;
 178
 179         /* May we inspect the given task?
 180          * This check is used both for attaching with ptrace
 181          * and for allowing access to sensitive information in /proc.
 182          *
 183          * ptrace_attach denies several cases that /proc allows
 184          * because setting up the necessary parent/child relationship
 185          * or halting the specified task is impossible.
 186          */
 187         int dumpable = 0;
 188         /* Don't let security modules deny introspection */
 189         if (task == current)
 190                 return 0;
 191         rcu_read_lock();
 192         tcred = __task_cred(task);
 193         if (cred->user->user_ns == tcred->user->user_ns &&
 194             (cred->uid == tcred->euid &&
 195              cred->uid == tcred->suid &&
 196              cred->uid == tcred->uid  &&
 197              cred->gid == tcred->egid &&
 198              cred->gid == tcred->sgid &&
 199              cred->gid == tcred->gid))
 200                 goto ok;
 201         if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE))
 202                 goto ok;
 203         rcu_read_unlock();
 204         return -EPERM;
 205 ok:
 206         rcu_read_unlock();
 207         smp_rmb();
 208         if (task->mm)
 209                 dumpable = get_dumpable(task->mm);
 210         if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE))
 211                 return -EPERM;
 212
 213         return security_ptrace_access_check(task, mode);
 214 }
 215
 216 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 217 {
 218         int err;
 219         task_lock(task);
 220         err = __ptrace_may_access(task, mode);
 221         task_unlock(task);
 222         return !err;
 223 }
 224
 225 static int ptrace_attach(struct task_struct *task, long request,
 226                          unsigned long flags)
 227 {
 228         bool seize = (request == PTRACE_SEIZE);
 229         int retval;
 230
 231         /*
 232          * SEIZE will enable new ptrace behaviors which will be implemented
 233          * gradually.  SEIZE_DEVEL is used to prevent applications
 234          * expecting full SEIZE behaviors trapping on kernel commits which
 235          * are still in the process of implementing them.
 236          *
 237          * Only test programs for new ptrace behaviors being implemented
 238          * should set SEIZE_DEVEL.  If unset, SEIZE will fail with -EIO.
 239          *
 240          * Once SEIZE behaviors are completely implemented, this flag and
 241          * the following test will be removed.
 242          */
 243         retval = -EIO;
 244         if (seize && !(flags & PTRACE_SEIZE_DEVEL))
 245                 goto out;
 246
 247         audit_ptrace(task);
 248
 249         retval = -EPERM;
 250         if (unlikely(task->flags & PF_KTHREAD))
 251                 goto out;
 252         if (same_thread_group(task, current))
 253                 goto out;
 254
 255         /*
 256          * Protect exec's credential calculations against our interference;
 257          * interference; SUID, SGID and LSM creds get determined differently
 258          * under ptrace.
 259          */
 260         retval = -ERESTARTNOINTR;
 261         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 262                 goto out;
 263
 264         task_lock(task);
 265         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 266         task_unlock(task);
 267         if (retval)
 268                 goto unlock_creds;
 269
 270         write_lock_irq(&tasklist_lock);
 271         retval = -EPERM;
 272         if (unlikely(task->exit_state))
 273                 goto unlock_tasklist;
 274         if (task->ptrace)
 275                 goto unlock_tasklist;
 276
 277         task->ptrace = PT_PTRACED;
 278         if (seize)
 279                 task->ptrace |= PT_SEIZED;
 280         if (task_ns_capable(task, CAP_SYS_PTRACE))
 281                 task->ptrace |= PT_PTRACE_CAP;
 282
 283         __ptrace_link(task, current);
 284
 285         /* SEIZE doesn't trap tracee on attach */
 286         if (!seize)
 287                 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 288
 289         spin_lock(&task->sighand->siglock);
 290
 291         /*
 292          * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
 293          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 294          * will be cleared if the child completes the transition or any
 295          * event which clears the group stop states happens.  We'll wait
 296          * for the transition to complete before returning from this
 297          * function.
 298          *
 299          * This hides STOPPED -> RUNNING -> TRACED transition from the
 300          * attaching thread but a different thread in the same group can
 301          * still observe the transient RUNNING state.  IOW, if another
 302          * thread's WNOHANG wait(2) on the stopped tracee races against
 303          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 304          *
 305          * The following task_is_stopped() test is safe as both transitions
 306          * in and out of STOPPED are protected by siglock.
 307          */
 308         if (task_is_stopped(task) &&
 309             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
 310                 signal_wake_up(task, 1);
 311
 312         spin_unlock(&task->sighand->siglock);
 313
 314         retval = 0;
 315 unlock_tasklist:
 316         write_unlock_irq(&tasklist_lock);
 317 unlock_creds:
 318         mutex_unlock(&task->signal->cred_guard_mutex);
 319 out:
 320         if (!retval) {
 321                 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
 322                             ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
 323                 proc_ptrace_connector(task, PTRACE_ATTACH);
 324         }
 325
 326         return retval;
 327 }
 328
 329 /**
 330  * ptrace_traceme  --  helper for PTRACE_TRACEME
 331  *
 332  * Performs checks and sets PT_PTRACED.
 333  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 334  */
 335 static int ptrace_traceme(void)
 336 {
 337         int ret = -EPERM;
 338
 339         write_lock_irq(&tasklist_lock);
 340         /* Are we already being traced? */
 341         if (!current->ptrace) {
 342                 ret = security_ptrace_traceme(current->parent);
 343                 /*
 344                  * Check PF_EXITING to ensure ->real_parent has not passed
 345                  * exit_ptrace(). Otherwise we don't report the error but
 346                  * pretend ->real_parent untraces us right after return.
 347                  */
 348                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 349                         current->ptrace = PT_PTRACED;
 350                         __ptrace_link(current, current->real_parent);
 351                 }
 352         }
 353         write_unlock_irq(&tasklist_lock);
 354
 355         return ret;
 356 }
 357
 358 /*
 359  * Called with irqs disabled, returns true if childs should reap themselves.
 360  */
 361 static int ignoring_children(struct sighand_struct *sigh)
 362 {
 363         int ret;
 364         spin_lock(&sigh->siglock);
 365         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 366               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 367         spin_unlock(&sigh->siglock);
 368         return ret;
 369 }
 370
 371 /*
 372  * Called with tasklist_lock held for writing.
 373  * Unlink a traced task, and clean it up if it was a traced zombie.
 374  * Return true if it needs to be reaped with release_task().
 375  * (We can't call release_task() here because we already hold tasklist_lock.)
 376  *
 377  * If it's a zombie, our attachedness prevented normal parent notification
 378  * or self-reaping.  Do notification now if it would have happened earlier.
 379  * If it should reap itself, return true.
 380  *
 381  * If it's our own child, there is no notification to do. But if our normal
 382  * children self-reap, then this child was prevented by ptrace and we must
 383  * reap it now, in that case we must also wake up sub-threads sleeping in
 384  * do_wait().
 385  */
 386 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 387 {
 388         bool dead;
 389
 390         __ptrace_unlink(p);
 391
 392         if (p->exit_state != EXIT_ZOMBIE)
 393                 return false;
 394
 395         dead = !thread_group_leader(p);
 396
 397         if (!dead && thread_group_empty(p)) {
 398                 if (!same_thread_group(p->real_parent, tracer))
 399                         dead = do_notify_parent(p, p->exit_signal);
 400                 else if (ignoring_children(tracer->sighand)) {
 401                         __wake_up_parent(p, tracer);
 402                         dead = true;
 403                 }
 404         }
 405         /* Mark it as in the process of being reaped. */
 406         if (dead)
 407                 p->exit_state = EXIT_DEAD;
 408         return dead;
 409 }
 410
 411 static int ptrace_detach(struct task_struct *child, unsigned int data)
 412 {
 413         bool dead = false;
 414
 415         if (!valid_signal(data))
 416                 return -EIO;
 417
 418         /* Architecture-specific hardware disable .. */
 419         ptrace_disable(child);
 420         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 421
 422         write_lock_irq(&tasklist_lock);
 423         /*
 424          * This child can be already killed. Make sure de_thread() or
 425          * our sub-thread doing do_wait() didn't do release_task() yet.
 426          */
 427         if (child->ptrace) {
 428                 child->exit_code = data;
 429                 dead = __ptrace_detach(current, child);
 430         }
 431         write_unlock_irq(&tasklist_lock);
 432
 433         proc_ptrace_connector(child, PTRACE_DETACH);
 434         if (unlikely(dead))
 435                 release_task(child);
 436
 437         return 0;
 438 }
 439
 440 /*
 441  * Detach all tasks we were using ptrace on. Called with tasklist held
 442  * for writing, and returns with it held too. But note it can release
 443  * and reacquire the lock.
 444  */
 445 void exit_ptrace(struct task_struct *tracer)
 446         __releases(&tasklist_lock)
 447         __acquires(&tasklist_lock)
 448 {
 449         struct task_struct *p, *n;
 450         LIST_HEAD(ptrace_dead);
 451
 452         if (likely(list_empty(&tracer->ptraced)))
 453                 return;
 454
 455         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 456                 if (__ptrace_detach(tracer, p))
 457                         list_add(&p->ptrace_entry, &ptrace_dead);
 458         }
 459
 460         write_unlock_irq(&tasklist_lock);
 461         BUG_ON(!list_empty(&tracer->ptraced));
 462
 463         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 464                 list_del_init(&p->ptrace_entry);
 465                 release_task(p);
 466         }
 467
 468         write_lock_irq(&tasklist_lock);
 469 }
 470
 471 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 472 {
 473         int copied = 0;
 474
 475         while (len > 0) {
 476                 char buf[128];
 477                 int this_len, retval;
 478
 479                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 480                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 481                 if (!retval) {
 482                         if (copied)
 483                                 break;
 484                         return -EIO;
 485                 }
 486                 if (copy_to_user(dst, buf, retval))
 487                         return -EFAULT;
 488                 copied += retval;
 489                 src += retval;
 490                 dst += retval;
 491                 len -= retval;
 492         }
 493         return copied;
 494 }
 495
 496 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 497 {
 498         int copied = 0;
 499
 500         while (len > 0) {
 501                 char buf[128];
 502                 int this_len, retval;
 503
 504                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 505                 if (copy_from_user(buf, src, this_len))
 506                         return -EFAULT;
 507                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 508                 if (!retval) {
 509                         if (copied)
 510                                 break;
 511                         return -EIO;
 512                 }
 513                 copied += retval;
 514                 src += retval;
 515                 dst += retval;
 516                 len -= retval;
 517         }
 518         return copied;
 519 }
 520
 521 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 522 {
 523         child->ptrace &= ~PT_TRACE_MASK;
 524
 525         if (data & PTRACE_O_TRACESYSGOOD)
 526                 child->ptrace |= PT_TRACESYSGOOD;
 527
 528         if (data & PTRACE_O_TRACEFORK)
 529                 child->ptrace |= PT_TRACE_FORK;
 530
 531         if (data & PTRACE_O_TRACEVFORK)
 532                 child->ptrace |= PT_TRACE_VFORK;
 533
 534         if (data & PTRACE_O_TRACECLONE)
 535                 child->ptrace |= PT_TRACE_CLONE;
 536
 537         if (data & PTRACE_O_TRACEEXEC)
 538                 child->ptrace |= PT_TRACE_EXEC;
 539
 540         if (data & PTRACE_O_TRACEVFORKDONE)
 541                 child->ptrace |= PT_TRACE_VFORK_DONE;
 542
 543         if (data & PTRACE_O_TRACEEXIT)
 544                 child->ptrace |= PT_TRACE_EXIT;
 545
 546         return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
 547 }
 548
 549 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 550 {
 551         unsigned long flags;
 552         int error = -ESRCH;
 553
 554         if (lock_task_sighand(child, &flags)) {
 555                 error = -EINVAL;
 556                 if (likely(child->last_siginfo != NULL)) {
 557                         *info = *child->last_siginfo;
 558                         error = 0;
 559                 }
 560                 unlock_task_sighand(child, &flags);
 561         }
 562         return error;
 563 }
 564
 565 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 566 {
 567         unsigned long flags;
 568         int error = -ESRCH;
 569
 570         if (lock_task_sighand(child, &flags)) {
 571                 error = -EINVAL;
 572                 if (likely(child->last_siginfo != NULL)) {
 573                         *child->last_siginfo = *info;
 574                         error = 0;
 575                 }
 576                 unlock_task_sighand(child, &flags);
 577         }
 578         return error;
 579 }
 580
 581
 582 #ifdef PTRACE_SINGLESTEP
 583 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 584 #else
 585 #define is_singlestep(request)          0
 586 #endif
 587
 588 #ifdef PTRACE_SINGLEBLOCK
 589 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 590 #else
 591 #define is_singleblock(request)         0
 592 #endif
 593
 594 #ifdef PTRACE_SYSEMU
 595 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 596 #else
 597 #define is_sysemu_singlestep(request)   0
 598 #endif
 599
 600 static int ptrace_resume(struct task_struct *child, long request,
 601                          unsigned long data)
 602 {
 603         if (!valid_signal(data))
 604                 return -EIO;
 605
 606         if (request == PTRACE_SYSCALL)
 607                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 608         else
 609                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 610
 611 #ifdef TIF_SYSCALL_EMU
 612         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 613                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 614         else
 615                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 616 #endif
 617
 618         if (is_singleblock(request)) {
 619                 if (unlikely(!arch_has_block_step()))
 620                         return -EIO;
 621                 user_enable_block_step(child);
 622         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 623                 if (unlikely(!arch_has_single_step()))
 624                         return -EIO;
 625                 user_enable_single_step(child);
 626         } else {
 627                 user_disable_single_step(child);
 628         }
 629
 630         child->exit_code = data;
 631         wake_up_state(child, __TASK_TRACED);
 632
 633         return 0;
 634 }
 635
 636 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 637
 638 static const struct user_regset *
 639 find_regset(const struct user_regset_view *view, unsigned int type)
 640 {
 641         const struct user_regset *regset;
 642         int n;
 643
 644         for (n = 0; n < view->n; ++n) {
 645                 regset = view->regsets + n;
 646                 if (regset->core_note_type == type)
 647                         return regset;
 648         }
 649
 650         return NULL;
 651 }
 652
 653 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 654                          struct iovec *kiov)
 655 {
 656         const struct user_regset_view *view = task_user_regset_view(task);
 657         const struct user_regset *regset = find_regset(view, type);
 658         int regset_no;
 659
 660         if (!regset || (kiov->iov_len % regset->size) != 0)
 661                 return -EINVAL;
 662
 663         regset_no = regset - view->regsets;
 664         kiov->iov_len = min(kiov->iov_len,
 665                             (__kernel_size_t) (regset->n * regset->size));
 666
 667         if (req == PTRACE_GETREGSET)
 668                 return copy_regset_to_user(task, view, regset_no, 0,
 669                                            kiov->iov_len, kiov->iov_base);
 670         else
 671                 return copy_regset_from_user(task, view, regset_no, 0,
 672                                              kiov->iov_len, kiov->iov_base);
 673 }
 674
 675 #endif
 676
 677 int ptrace_request(struct task_struct *child, long request,
 678                    unsigned long addr, unsigned long data)
 679 {
 680         bool seized = child->ptrace & PT_SEIZED;
 681         int ret = -EIO;
 682         siginfo_t siginfo, *si;
 683         void __user *datavp = (void __user *) data;
 684         unsigned long __user *datalp = datavp;
 685         unsigned long flags;
 686
 687         switch (request) {
 688         case PTRACE_PEEKTEXT:
 689         case PTRACE_PEEKDATA:
 690                 return generic_ptrace_peekdata(child, addr, data);
 691         case PTRACE_POKETEXT:
 692         case PTRACE_POKEDATA:
 693                 return generic_ptrace_pokedata(child, addr, data);
 694
 695 #ifdef PTRACE_OLDSETOPTIONS
 696         case PTRACE_OLDSETOPTIONS:
 697 #endif
 698         case PTRACE_SETOPTIONS:
 699                 ret = ptrace_setoptions(child, data);
 700                 break;
 701         case PTRACE_GETEVENTMSG:
 702                 ret = put_user(child->ptrace_message, datalp);
 703                 break;
 704
 705         case PTRACE_GETSIGINFO:
 706                 ret = ptrace_getsiginfo(child, &siginfo);
 707                 if (!ret)
 708                         ret = copy_siginfo_to_user(datavp, &siginfo);
 709                 break;
 710
 711         case PTRACE_SETSIGINFO:
 712                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 713                         ret = -EFAULT;
 714                 else
 715                         ret = ptrace_setsiginfo(child, &siginfo);
 716                 break;
 717
 718         case PTRACE_INTERRUPT:
 719                 /*
 720                  * Stop tracee without any side-effect on signal or job
 721                  * control.  At least one trap is guaranteed to happen
 722                  * after this request.  If @child is already trapped, the
 723                  * current trap is not disturbed and another trap will
 724                  * happen after the current trap is ended with PTRACE_CONT.
 725                  *
 726                  * The actual trap might not be PTRACE_EVENT_STOP trap but
 727                  * the pending condition is cleared regardless.
 728                  */
 729                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 730                         break;
 731
 732                 /*
 733                  * INTERRUPT doesn't disturb existing trap sans one
 734                  * exception.  If ptracer issued LISTEN for the current
 735                  * STOP, this INTERRUPT should clear LISTEN and re-trap
 736                  * tracee into STOP.
 737                  */
 738                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
 739                         signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
 740
 741                 unlock_task_sighand(child, &flags);
 742                 ret = 0;
 743                 break;
 744
 745         case PTRACE_LISTEN:
 746                 /*
 747                  * Listen for events.  Tracee must be in STOP.  It's not
 748                  * resumed per-se but is not considered to be in TRACED by
 749                  * wait(2) or ptrace(2).  If an async event (e.g. group
 750                  * stop state change) happens, tracee will enter STOP trap
 751                  * again.  Alternatively, ptracer can issue INTERRUPT to
 752                  * finish listening and re-trap tracee into STOP.
 753                  */
 754                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 755                         break;
 756
 757                 si = child->last_siginfo;
 758                 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
 759                         child->jobctl |= JOBCTL_LISTENING;
 760                         /*
 761                          * If NOTIFY is set, it means event happened between
 762                          * start of this trap and now.  Trigger re-trap.
 763                          */
 764                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
 765                                 signal_wake_up(child, true);
 766                         ret = 0;
 767                 }
 768                 unlock_task_sighand(child, &flags);
 769                 break;
 770
 771         case PTRACE_DETACH:      /* detach a process that was attached. */
 772                 ret = ptrace_detach(child, data);
 773                 break;
 774
 775 #ifdef CONFIG_BINFMT_ELF_FDPIC
 776         case PTRACE_GETFDPIC: {
 777                 struct mm_struct *mm = get_task_mm(child);
 778                 unsigned long tmp = 0;
 779
 780                 ret = -ESRCH;
 781                 if (!mm)
 782                         break;
 783
 784                 switch (addr) {
 785                 case PTRACE_GETFDPIC_EXEC:
 786                         tmp = mm->context.exec_fdpic_loadmap;
 787                         break;
 788                 case PTRACE_GETFDPIC_INTERP:
 789                         tmp = mm->context.interp_fdpic_loadmap;
 790                         break;
 791                 default:
 792                         break;
 793                 }
 794                 mmput(mm);
 795
 796                 ret = put_user(tmp, datalp);
 797                 break;
 798         }
 799 #endif
 800
 801 #ifdef PTRACE_SINGLESTEP
 802         case PTRACE_SINGLESTEP:
 803 #endif
 804 #ifdef PTRACE_SINGLEBLOCK
 805         case PTRACE_SINGLEBLOCK:
 806 #endif
 807 #ifdef PTRACE_SYSEMU
 808         case PTRACE_SYSEMU:
 809         case PTRACE_SYSEMU_SINGLESTEP:
 810 #endif
 811         case PTRACE_SYSCALL:
 812         case PTRACE_CONT:
 813                 return ptrace_resume(child, request, data);
 814
 815         case PTRACE_KILL:
 816                 if (child->exit_state)  /* already dead */
 817                         return 0;
 818                 return ptrace_resume(child, request, SIGKILL);
 819
 820 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 821         case PTRACE_GETREGSET:
 822         case PTRACE_SETREGSET:
 823         {
 824                 struct iovec kiov;
 825                 struct iovec __user *uiov = datavp;
 826
 827                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 828                         return -EFAULT;
 829
 830                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 831                     __get_user(kiov.iov_len, &uiov->iov_len))
 832                         return -EFAULT;
 833
 834                 ret = ptrace_regset(child, request, addr, &kiov);
 835                 if (!ret)
 836                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 837                 break;
 838         }
 839 #endif
 840         default:
 841                 break;
 842         }
 843
 844         return ret;
 845 }
 846
 847 static struct task_struct *ptrace_get_task_struct(pid_t pid)
 848 {
 849         struct task_struct *child;
 850
 851         rcu_read_lock();
 852         child = find_task_by_vpid(pid);
 853         if (child)
 854                 get_task_struct(child);
 855         rcu_read_unlock();
 856
 857         if (!child)
 858                 return ERR_PTR(-ESRCH);
 859         return child;
 860 }
 861
 862 #ifndef arch_ptrace_attach
 863 #define arch_ptrace_attach(child)       do { } while (0)
 864 #endif
 865
 866 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 867                 unsigned long, data)
 868 {
 869         struct task_struct *child;
 870         long ret;
 871
 872         if (request == PTRACE_TRACEME) {
 873                 ret = ptrace_traceme();
 874                 if (!ret)
 875                         arch_ptrace_attach(current);
 876                 goto out;
 877         }
 878
 879         child = ptrace_get_task_struct(pid);
 880         if (IS_ERR(child)) {
 881                 ret = PTR_ERR(child);
 882                 goto out;
 883         }
 884
 885         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 886                 ret = ptrace_attach(child, request, data);
 887                 /*
 888                  * Some architectures need to do book-keeping after
 889                  * a ptrace attach.
 890                  */
 891                 if (!ret)
 892                         arch_ptrace_attach(child);
 893                 goto out_put_task_struct;
 894         }
 895
 896         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
 897                                   request == PTRACE_INTERRUPT);
 898         if (ret < 0)
 899                 goto out_put_task_struct;
 900
 901         ret = arch_ptrace(child, request, addr, data);
 902
 903  out_put_task_struct:
 904         put_task_struct(child);
 905  out:
 906         return ret;
 907 }
 908
 909 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 910                             unsigned long data)
 911 {
 912         unsigned long tmp;
 913         int copied;
 914
 915         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 916         if (copied != sizeof(tmp))
 917                 return -EIO;
 918         return put_user(tmp, (unsigned long __user *)data);
 919 }
 920
 921 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 922                             unsigned long data)
 923 {
 924         int copied;
 925
 926         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 927         return (copied == sizeof(data)) ? 0 : -EIO;
 928 }
 929
 930 #if defined CONFIG_COMPAT
 931 #include <linux/compat.h>
 932
 933 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 934                           compat_ulong_t addr, compat_ulong_t data)
 935 {
 936         compat_ulong_t __user *datap = compat_ptr(data);
 937         compat_ulong_t word;
 938         siginfo_t siginfo;
 939         int ret;
 940
 941         switch (request) {
 942         case PTRACE_PEEKTEXT:
 943         case PTRACE_PEEKDATA:
 944                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 945                 if (ret != sizeof(word))
 946                         ret = -EIO;
 947                 else
 948                         ret = put_user(word, datap);
 949                 break;
 950
 951         case PTRACE_POKETEXT:
 952         case PTRACE_POKEDATA:
 953                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 954                 ret = (ret != sizeof(data) ? -EIO : 0);
 955                 break;
 956
 957         case PTRACE_GETEVENTMSG:
 958                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 959                 break;
 960
 961         case PTRACE_GETSIGINFO:
 962                 ret = ptrace_getsiginfo(child, &siginfo);
 963                 if (!ret)
 964                         ret = copy_siginfo_to_user32(
 965                                 (struct compat_siginfo __user *) datap,
 966                                 &siginfo);
 967                 break;
 968
 969         case PTRACE_SETSIGINFO:
 970                 memset(&siginfo, 0, sizeof siginfo);
 971                 if (copy_siginfo_from_user32(
 972                             &siginfo, (struct compat_siginfo __user *) datap))
 973                         ret = -EFAULT;
 974                 else
 975                         ret = ptrace_setsiginfo(child, &siginfo);
 976                 break;
 977 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 978         case PTRACE_GETREGSET:
 979         case PTRACE_SETREGSET:
 980         {
 981                 struct iovec kiov;
 982                 struct compat_iovec __user *uiov =
 983                         (struct compat_iovec __user *) datap;
 984                 compat_uptr_t ptr;
 985                 compat_size_t len;
 986
 987                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 988                         return -EFAULT;
 989
 990                 if (__get_user(ptr, &uiov->iov_base) ||
 991                     __get_user(len, &uiov->iov_len))
 992                         return -EFAULT;
 993
 994                 kiov.iov_base = compat_ptr(ptr);
 995                 kiov.iov_len = len;
 996
 997                 ret = ptrace_regset(child, request, addr, &kiov);
 998                 if (!ret)
 999                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1000                 break;
1001         }
1002 #endif
1003
1004         default:
1005                 ret = ptrace_request(child, request, addr, data);
1006         }
1007
1008         return ret;
1009 }
1010
1011 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
1012                                   compat_long_t addr, compat_long_t data)
1013 {
1014         struct task_struct *child;
1015         long ret;
1016
1017         if (request == PTRACE_TRACEME) {
1018                 ret = ptrace_traceme();
1019                 goto out;
1020         }
1021
1022         child = ptrace_get_task_struct(pid);
1023         if (IS_ERR(child)) {
1024                 ret = PTR_ERR(child);
1025                 goto out;
1026         }
1027
1028         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1029                 ret = ptrace_attach(child, request, data);
1030                 /*
1031                  * Some architectures need to do book-keeping after
1032                  * a ptrace attach.
1033                  */
1034                 if (!ret)
1035                         arch_ptrace_attach(child);
1036                 goto out_put_task_struct;
1037         }
1038
1039         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1040                                   request == PTRACE_INTERRUPT);
1041         if (!ret)
1042                 ret = compat_arch_ptrace(child, request, addr, data);
1043
1044  out_put_task_struct:
1045         put_task_struct(child);
1046  out:
1047         return ret;
1048 }
1049 #endif  /* CONFIG_COMPAT */
1050
1051 #ifdef CONFIG_HAVE_HW_BREAKPOINT
1052 int ptrace_get_breakpoints(struct task_struct *tsk)
1053 {
1054         if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
1055                 return 0;
1056
1057         return -1;
1058 }
1059
1060 void ptrace_put_breakpoints(struct task_struct *tsk)
1061 {
1062         if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
1063                 flush_ptrace_hw_breakpoint(tsk);
1064 }
1065 #endif /* CONFIG_HAVE_HW_BREAKPOINT */