kernel/ptrace.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/kernel/ptrace.c
   4  *
   5  * (C) Copyright 1999 Linus Torvalds
   6  *
   7  * Common interfaces for "ptrace()" which we do not want
   8  * to continually duplicate across every architecture.
   9  */
  10
  11 #include <linux/capability.h>
  12 #include <linux/export.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/mm.h>
  15 #include <linux/sched/coredump.h>
  16 #include <linux/sched/task.h>
  17 #include <linux/errno.h>
  18 #include <linux/mm.h>
  19 #include <linux/highmem.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/security.h>
  23 #include <linux/signal.h>
  24 #include <linux/uio.h>
  25 #include <linux/audit.h>
  26 #include <linux/pid_namespace.h>
  27 #include <linux/syscalls.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/regset.h>
  30 #include <linux/hw_breakpoint.h>
  31 #include <linux/cn_proc.h>
  32 #include <linux/compat.h>
  33 #include <linux/sched/signal.h>
  34
  35 #include <asm/syscall.h>        /* for syscall_get_* */
  36
  37 /*
  38  * Access another process' address space via ptrace.
  39  * Source/target buffer must be kernel space,
  40  * Do not walk the page table directly, use get_user_pages
  41  */
  42 int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
  43                      void *buf, int len, unsigned int gup_flags)
  44 {
  45         struct mm_struct *mm;
  46         int ret;
  47
  48         mm = get_task_mm(tsk);
  49         if (!mm)
  50                 return 0;
  51
  52         if (!tsk->ptrace ||
  53             (current != tsk->parent) ||
  54             ((get_dumpable(mm) != SUID_DUMP_USER) &&
  55              !ptracer_capable(tsk, mm->user_ns))) {
  56                 mmput(mm);
  57                 return 0;
  58         }
  59
  60         ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
  61         mmput(mm);
  62
  63         return ret;
  64 }
  65
  66
  67 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent,
  68                    const struct cred *ptracer_cred)
  69 {
  70         BUG_ON(!list_empty(&child->ptrace_entry));
  71         list_add(&child->ptrace_entry, &new_parent->ptraced);
  72         child->parent = new_parent;
  73         child->ptracer_cred = get_cred(ptracer_cred);
  74 }
  75
  76 /*
  77  * ptrace a task: make the debugger its new parent and
  78  * move it to the ptrace list.
  79  *
  80  * Must be called with the tasklist lock write-held.
  81  */
  82 static void ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  83 {
  84         __ptrace_link(child, new_parent, current_cred());
  85 }
  86
  87 /**
  88  * __ptrace_unlink - unlink ptracee and restore its execution state
  89  * @child: ptracee to be unlinked
  90  *
  91  * Remove @child from the ptrace list, move it back to the original parent,
  92  * and restore the execution state so that it conforms to the group stop
  93  * state.
  94  *
  95  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  96  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  97  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  98  * If the ptracer is exiting, the ptracee can be in any state.
  99  *
 100  * After detach, the ptracee should be in a state which conforms to the
 101  * group stop.  If the group is stopped or in the process of stopping, the
 102  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
 103  * up from TASK_TRACED.
 104  *
 105  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
 106  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
 107  * to but in the opposite direction of what happens while attaching to a
 108  * stopped task.  However, in this direction, the intermediate RUNNING
 109  * state is not hidden even from the current ptracer and if it immediately
 110  * re-attaches and performs a WNOHANG wait(2), it may fail.
 111  *
 112  * CONTEXT:
 113  * write_lock_irq(tasklist_lock)
 114  */
 115 void __ptrace_unlink(struct task_struct *child)
 116 {
 117         const struct cred *old_cred;
 118         BUG_ON(!child->ptrace);
 119
 120         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 121 #ifdef TIF_SYSCALL_EMU
 122         clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 123 #endif
 124
 125         child->parent = child->real_parent;
 126         list_del_init(&child->ptrace_entry);
 127         old_cred = child->ptracer_cred;
 128         child->ptracer_cred = NULL;
 129         put_cred(old_cred);
 130
 131         spin_lock(&child->sighand->siglock);
 132         child->ptrace = 0;
 133         /*
 134          * Clear all pending traps and TRAPPING.  TRAPPING should be
 135          * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
 136          */
 137         task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
 138         task_clear_jobctl_trapping(child);
 139
 140         /*
 141          * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
 142          * @child isn't dead.
 143          */
 144         if (!(child->flags & PF_EXITING) &&
 145             (child->signal->flags & SIGNAL_STOP_STOPPED ||
 146              child->signal->group_stop_count)) {
 147                 child->jobctl |= JOBCTL_STOP_PENDING;
 148
 149                 /*
 150                  * This is only possible if this thread was cloned by the
 151                  * traced task running in the stopped group, set the signal
 152                  * for the future reports.
 153                  * FIXME: we should change ptrace_init_task() to handle this
 154                  * case.
 155                  */
 156                 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
 157                         child->jobctl |= SIGSTOP;
 158         }
 159
 160         /*
 161          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
 162          * @child in the butt.  Note that @resume should be used iff @child
 163          * is in TASK_TRACED; otherwise, we might unduly disrupt
 164          * TASK_KILLABLE sleeps.
 165          */
 166         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
 167                 ptrace_signal_wake_up(child, true);
 168
 169         spin_unlock(&child->sighand->siglock);
 170 }
 171
 172 /* Ensure that nothing can wake it up, even SIGKILL */
 173 static bool ptrace_freeze_traced(struct task_struct *task)
 174 {
 175         bool ret = false;
 176
 177         /* Lockless, nobody but us can set this flag */
 178         if (task->jobctl & JOBCTL_LISTENING)
 179                 return ret;
 180
 181         spin_lock_irq(&task->sighand->siglock);
 182         if (task_is_traced(task) && !__fatal_signal_pending(task)) {
 183                 task->state = __TASK_TRACED;
 184                 ret = true;
 185         }
 186         spin_unlock_irq(&task->sighand->siglock);
 187
 188         return ret;
 189 }
 190
 191 static void ptrace_unfreeze_traced(struct task_struct *task)
 192 {
 193         if (task->state != __TASK_TRACED)
 194                 return;
 195
 196         WARN_ON(!task->ptrace || task->parent != current);
 197
 198         /*
 199          * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
 200          * Recheck state under the lock to close this race.
 201          */
 202         spin_lock_irq(&task->sighand->siglock);
 203         if (task->state == __TASK_TRACED) {
 204                 if (__fatal_signal_pending(task))
 205                         wake_up_state(task, __TASK_TRACED);
 206                 else
 207                         task->state = TASK_TRACED;
 208         }
 209         spin_unlock_irq(&task->sighand->siglock);
 210 }
 211
 212 /**
 213  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
 214  * @child: ptracee to check for
 215  * @ignore_state: don't check whether @child is currently %TASK_TRACED
 216  *
 217  * Check whether @child is being ptraced by %current and ready for further
 218  * ptrace operations.  If @ignore_state is %false, @child also should be in
 219  * %TASK_TRACED state and on return the child is guaranteed to be traced
 220  * and not executing.  If @ignore_state is %true, @child can be in any
 221  * state.
 222  *
 223  * CONTEXT:
 224  * Grabs and releases tasklist_lock and @child->sighand->siglock.
 225  *
 226  * RETURNS:
 227  * 0 on success, -ESRCH if %child is not ready.
 228  */
 229 static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 230 {
 231         int ret = -ESRCH;
 232
 233         /*
 234          * We take the read lock around doing both checks to close a
 235          * possible race where someone else was tracing our child and
 236          * detached between these two checks.  After this locked check,
 237          * we are sure that this is our traced child and that can only
 238          * be changed by us so it's not changing right after this.
 239          */
 240         read_lock(&tasklist_lock);
 241         if (child->ptrace && child->parent == current) {
 242                 WARN_ON(child->state == __TASK_TRACED);
 243                 /*
 244                  * child->sighand can't be NULL, release_task()
 245                  * does ptrace_unlink() before __exit_signal().
 246                  */
 247                 if (ignore_state || ptrace_freeze_traced(child))
 248                         ret = 0;
 249         }
 250         read_unlock(&tasklist_lock);
 251
 252         if (!ret && !ignore_state) {
 253                 if (!wait_task_inactive(child, __TASK_TRACED)) {
 254                         /*
 255                          * This can only happen if may_ptrace_stop() fails and
 256                          * ptrace_stop() changes ->state back to TASK_RUNNING,
 257                          * so we should not worry about leaking __TASK_TRACED.
 258                          */
 259                         WARN_ON(child->state == __TASK_TRACED);
 260                         ret = -ESRCH;
 261                 }
 262         }
 263
 264         return ret;
 265 }
 266
 267 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 268 {
 269         if (mode & PTRACE_MODE_NOAUDIT)
 270                 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
 271         else
 272                 return has_ns_capability(current, ns, CAP_SYS_PTRACE);
 273 }
 274
 275 /* Returns 0 on success, -errno on denial. */
 276 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 277 {
 278         const struct cred *cred = current_cred(), *tcred;
 279         struct mm_struct *mm;
 280         kuid_t caller_uid;
 281         kgid_t caller_gid;
 282
 283         if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) {
 284                 WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n");
 285                 return -EPERM;
 286         }
 287
 288         /* May we inspect the given task?
 289          * This check is used both for attaching with ptrace
 290          * and for allowing access to sensitive information in /proc.
 291          *
 292          * ptrace_attach denies several cases that /proc allows
 293          * because setting up the necessary parent/child relationship
 294          * or halting the specified task is impossible.
 295          */
 296
 297         /* Don't let security modules deny introspection */
 298         if (same_thread_group(task, current))
 299                 return 0;
 300         rcu_read_lock();
 301         if (mode & PTRACE_MODE_FSCREDS) {
 302                 caller_uid = cred->fsuid;
 303                 caller_gid = cred->fsgid;
 304         } else {
 305                 /*
 306                  * Using the euid would make more sense here, but something
 307                  * in userland might rely on the old behavior, and this
 308                  * shouldn't be a security problem since
 309                  * PTRACE_MODE_REALCREDS implies that the caller explicitly
 310                  * used a syscall that requests access to another process
 311                  * (and not a filesystem syscall to procfs).
 312                  */
 313                 caller_uid = cred->uid;
 314                 caller_gid = cred->gid;
 315         }
 316         tcred = __task_cred(task);
 317         if (uid_eq(caller_uid, tcred->euid) &&
 318             uid_eq(caller_uid, tcred->suid) &&
 319             uid_eq(caller_uid, tcred->uid)  &&
 320             gid_eq(caller_gid, tcred->egid) &&
 321             gid_eq(caller_gid, tcred->sgid) &&
 322             gid_eq(caller_gid, tcred->gid))
 323                 goto ok;
 324         if (ptrace_has_cap(tcred->user_ns, mode))
 325                 goto ok;
 326         rcu_read_unlock();
 327         return -EPERM;
 328 ok:
 329         rcu_read_unlock();
 330         /*
 331          * If a task drops privileges and becomes nondumpable (through a syscall
 332          * like setresuid()) while we are trying to access it, we must ensure
 333          * that the dumpability is read after the credentials; otherwise,
 334          * we may be able to attach to a task that we shouldn't be able to
 335          * attach to (as if the task had dropped privileges without becoming
 336          * nondumpable).
 337          * Pairs with a write barrier in commit_creds().
 338          */
 339         smp_rmb();
 340         mm = task->mm;
 341         if (mm &&
 342             ((get_dumpable(mm) != SUID_DUMP_USER) &&
 343              !ptrace_has_cap(mm->user_ns, mode)))
 344             return -EPERM;
 345
 346         return security_ptrace_access_check(task, mode);
 347 }
 348
 349 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 350 {
 351         int err;
 352         task_lock(task);
 353         err = __ptrace_may_access(task, mode);
 354         task_unlock(task);
 355         return !err;
 356 }
 357
 358 static int ptrace_attach(struct task_struct *task, long request,
 359                          unsigned long addr,
 360                          unsigned long flags)
 361 {
 362         bool seize = (request == PTRACE_SEIZE);
 363         int retval;
 364
 365         retval = -EIO;
 366         if (seize) {
 367                 if (addr != 0)
 368                         goto out;
 369                 if (flags & ~(unsigned long)PTRACE_O_MASK)
 370                         goto out;
 371                 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
 372         } else {
 373                 flags = PT_PTRACED;
 374         }
 375
 376         audit_ptrace(task);
 377
 378         retval = -EPERM;
 379         if (unlikely(task->flags & PF_KTHREAD))
 380                 goto out;
 381         if (same_thread_group(task, current))
 382                 goto out;
 383
 384         /*
 385          * Protect exec's credential calculations against our interference;
 386          * SUID, SGID and LSM creds get determined differently
 387          * under ptrace.
 388          */
 389         retval = -ERESTARTNOINTR;
 390         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 391                 goto out;
 392
 393         task_lock(task);
 394         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS);
 395         task_unlock(task);
 396         if (retval)
 397                 goto unlock_creds;
 398
 399         write_lock_irq(&tasklist_lock);
 400         retval = -EPERM;
 401         if (unlikely(task->exit_state))
 402                 goto unlock_tasklist;
 403         if (task->ptrace)
 404                 goto unlock_tasklist;
 405
 406         if (seize)
 407                 flags |= PT_SEIZED;
 408         task->ptrace = flags;
 409
 410         ptrace_link(task, current);
 411
 412         /* SEIZE doesn't trap tracee on attach */
 413         if (!seize)
 414                 send_sig_info(SIGSTOP, SEND_SIG_PRIV, task);
 415
 416         spin_lock(&task->sighand->siglock);
 417
 418         /*
 419          * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
 420          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 421          * will be cleared if the child completes the transition or any
 422          * event which clears the group stop states happens.  We'll wait
 423          * for the transition to complete before returning from this
 424          * function.
 425          *
 426          * This hides STOPPED -> RUNNING -> TRACED transition from the
 427          * attaching thread but a different thread in the same group can
 428          * still observe the transient RUNNING state.  IOW, if another
 429          * thread's WNOHANG wait(2) on the stopped tracee races against
 430          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 431          *
 432          * The following task_is_stopped() test is safe as both transitions
 433          * in and out of STOPPED are protected by siglock.
 434          */
 435         if (task_is_stopped(task) &&
 436             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
 437                 signal_wake_up_state(task, __TASK_STOPPED);
 438
 439         spin_unlock(&task->sighand->siglock);
 440
 441         retval = 0;
 442 unlock_tasklist:
 443         write_unlock_irq(&tasklist_lock);
 444 unlock_creds:
 445         mutex_unlock(&task->signal->cred_guard_mutex);
 446 out:
 447         if (!retval) {
 448                 /*
 449                  * We do not bother to change retval or clear JOBCTL_TRAPPING
 450                  * if wait_on_bit() was interrupted by SIGKILL. The tracer will
 451                  * not return to user-mode, it will exit and clear this bit in
 452                  * __ptrace_unlink() if it wasn't already cleared by the tracee;
 453                  * and until then nobody can ptrace this task.
 454                  */
 455                 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE);
 456                 proc_ptrace_connector(task, PTRACE_ATTACH);
 457         }
 458
 459         return retval;
 460 }
 461
 462 /**
 463  * ptrace_traceme  --  helper for PTRACE_TRACEME
 464  *
 465  * Performs checks and sets PT_PTRACED.
 466  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 467  */
 468 static int ptrace_traceme(void)
 469 {
 470         int ret = -EPERM;
 471
 472         write_lock_irq(&tasklist_lock);
 473         /* Are we already being traced? */
 474         if (!current->ptrace) {
 475                 ret = security_ptrace_traceme(current->parent);
 476                 /*
 477                  * Check PF_EXITING to ensure ->real_parent has not passed
 478                  * exit_ptrace(). Otherwise we don't report the error but
 479                  * pretend ->real_parent untraces us right after return.
 480                  */
 481                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 482                         current->ptrace = PT_PTRACED;
 483                         ptrace_link(current, current->real_parent);
 484                 }
 485         }
 486         write_unlock_irq(&tasklist_lock);
 487
 488         return ret;
 489 }
 490
 491 /*
 492  * Called with irqs disabled, returns true if childs should reap themselves.
 493  */
 494 static int ignoring_children(struct sighand_struct *sigh)
 495 {
 496         int ret;
 497         spin_lock(&sigh->siglock);
 498         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 499               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 500         spin_unlock(&sigh->siglock);
 501         return ret;
 502 }
 503
 504 /*
 505  * Called with tasklist_lock held for writing.
 506  * Unlink a traced task, and clean it up if it was a traced zombie.
 507  * Return true if it needs to be reaped with release_task().
 508  * (We can't call release_task() here because we already hold tasklist_lock.)
 509  *
 510  * If it's a zombie, our attachedness prevented normal parent notification
 511  * or self-reaping.  Do notification now if it would have happened earlier.
 512  * If it should reap itself, return true.
 513  *
 514  * If it's our own child, there is no notification to do. But if our normal
 515  * children self-reap, then this child was prevented by ptrace and we must
 516  * reap it now, in that case we must also wake up sub-threads sleeping in
 517  * do_wait().
 518  */
 519 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 520 {
 521         bool dead;
 522
 523         __ptrace_unlink(p);
 524
 525         if (p->exit_state != EXIT_ZOMBIE)
 526                 return false;
 527
 528         dead = !thread_group_leader(p);
 529
 530         if (!dead && thread_group_empty(p)) {
 531                 if (!same_thread_group(p->real_parent, tracer))
 532                         dead = do_notify_parent(p, p->exit_signal);
 533                 else if (ignoring_children(tracer->sighand)) {
 534                         __wake_up_parent(p, tracer);
 535                         dead = true;
 536                 }
 537         }
 538         /* Mark it as in the process of being reaped. */
 539         if (dead)
 540                 p->exit_state = EXIT_DEAD;
 541         return dead;
 542 }
 543
 544 static int ptrace_detach(struct task_struct *child, unsigned int data)
 545 {
 546         if (!valid_signal(data))
 547                 return -EIO;
 548
 549         /* Architecture-specific hardware disable .. */
 550         ptrace_disable(child);
 551
 552         write_lock_irq(&tasklist_lock);
 553         /*
 554          * We rely on ptrace_freeze_traced(). It can't be killed and
 555          * untraced by another thread, it can't be a zombie.
 556          */
 557         WARN_ON(!child->ptrace || child->exit_state);
 558         /*
 559          * tasklist_lock avoids the race with wait_task_stopped(), see
 560          * the comment in ptrace_resume().
 561          */
 562         child->exit_code = data;
 563         __ptrace_detach(current, child);
 564         write_unlock_irq(&tasklist_lock);
 565
 566         proc_ptrace_connector(child, PTRACE_DETACH);
 567
 568         return 0;
 569 }
 570
 571 /*
 572  * Detach all tasks we were using ptrace on. Called with tasklist held
 573  * for writing.
 574  */
 575 void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
 576 {
 577         struct task_struct *p, *n;
 578
 579         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 580                 if (unlikely(p->ptrace & PT_EXITKILL))
 581                         send_sig_info(SIGKILL, SEND_SIG_PRIV, p);
 582
 583                 if (__ptrace_detach(tracer, p))
 584                         list_add(&p->ptrace_entry, dead);
 585         }
 586 }
 587
 588 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 589 {
 590         int copied = 0;
 591
 592         while (len > 0) {
 593                 char buf[128];
 594                 int this_len, retval;
 595
 596                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 597                 retval = ptrace_access_vm(tsk, src, buf, this_len, FOLL_FORCE);
 598
 599                 if (!retval) {
 600                         if (copied)
 601                                 break;
 602                         return -EIO;
 603                 }
 604                 if (copy_to_user(dst, buf, retval))
 605                         return -EFAULT;
 606                 copied += retval;
 607                 src += retval;
 608                 dst += retval;
 609                 len -= retval;
 610         }
 611         return copied;
 612 }
 613
 614 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 615 {
 616         int copied = 0;
 617
 618         while (len > 0) {
 619                 char buf[128];
 620                 int this_len, retval;
 621
 622                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 623                 if (copy_from_user(buf, src, this_len))
 624                         return -EFAULT;
 625                 retval = ptrace_access_vm(tsk, dst, buf, this_len,
 626                                 FOLL_FORCE | FOLL_WRITE);
 627                 if (!retval) {
 628                         if (copied)
 629                                 break;
 630                         return -EIO;
 631                 }
 632                 copied += retval;
 633                 src += retval;
 634                 dst += retval;
 635                 len -= retval;
 636         }
 637         return copied;
 638 }
 639
 640 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 641 {
 642         unsigned flags;
 643
 644         if (data & ~(unsigned long)PTRACE_O_MASK)
 645                 return -EINVAL;
 646
 647         if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
 648                 if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
 649                     !IS_ENABLED(CONFIG_SECCOMP))
 650                         return -EINVAL;
 651
 652                 if (!capable(CAP_SYS_ADMIN))
 653                         return -EPERM;
 654
 655                 if (seccomp_mode(&current->seccomp) != SECCOMP_MODE_DISABLED ||
 656                     current->ptrace & PT_SUSPEND_SECCOMP)
 657                         return -EPERM;
 658         }
 659
 660         /* Avoid intermediate state when all opts are cleared */
 661         flags = child->ptrace;
 662         flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
 663         flags |= (data << PT_OPT_FLAG_SHIFT);
 664         child->ptrace = flags;
 665
 666         return 0;
 667 }
 668
 669 static int ptrace_getsiginfo(struct task_struct *child, kernel_siginfo_t *info)
 670 {
 671         unsigned long flags;
 672         int error = -ESRCH;
 673
 674         if (lock_task_sighand(child, &flags)) {
 675                 error = -EINVAL;
 676                 if (likely(child->last_siginfo != NULL)) {
 677                         copy_siginfo(info, child->last_siginfo);
 678                         error = 0;
 679                 }
 680                 unlock_task_sighand(child, &flags);
 681         }
 682         return error;
 683 }
 684
 685 static int ptrace_setsiginfo(struct task_struct *child, const kernel_siginfo_t *info)
 686 {
 687         unsigned long flags;
 688         int error = -ESRCH;
 689
 690         if (lock_task_sighand(child, &flags)) {
 691                 error = -EINVAL;
 692                 if (likely(child->last_siginfo != NULL)) {
 693                         copy_siginfo(child->last_siginfo, info);
 694                         error = 0;
 695                 }
 696                 unlock_task_sighand(child, &flags);
 697         }
 698         return error;
 699 }
 700
 701 static int ptrace_peek_siginfo(struct task_struct *child,
 702                                 unsigned long addr,
 703                                 unsigned long data)
 704 {
 705         struct ptrace_peeksiginfo_args arg;
 706         struct sigpending *pending;
 707         struct sigqueue *q;
 708         int ret, i;
 709
 710         ret = copy_from_user(&arg, (void __user *) addr,
 711                                 sizeof(struct ptrace_peeksiginfo_args));
 712         if (ret)
 713                 return -EFAULT;
 714
 715         if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
 716                 return -EINVAL; /* unknown flags */
 717
 718         if (arg.nr < 0)
 719                 return -EINVAL;
 720
 721         /* Ensure arg.off fits in an unsigned long */
 722         if (arg.off > ULONG_MAX)
 723                 return 0;
 724
 725         if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
 726                 pending = &child->signal->shared_pending;
 727         else
 728                 pending = &child->pending;
 729
 730         for (i = 0; i < arg.nr; ) {
 731                 kernel_siginfo_t info;
 732                 unsigned long off = arg.off + i;
 733                 bool found = false;
 734
 735                 spin_lock_irq(&child->sighand->siglock);
 736                 list_for_each_entry(q, &pending->list, list) {
 737                         if (!off--) {
 738                                 found = true;
 739                                 copy_siginfo(&info, &q->info);
 740                                 break;
 741                         }
 742                 }
 743                 spin_unlock_irq(&child->sighand->siglock);
 744
 745                 if (!found) /* beyond the end of the list */
 746                         break;
 747
 748 #ifdef CONFIG_COMPAT
 749                 if (unlikely(in_compat_syscall())) {
 750                         compat_siginfo_t __user *uinfo = compat_ptr(data);
 751
 752                         if (copy_siginfo_to_user32(uinfo, &info)) {
 753                                 ret = -EFAULT;
 754                                 break;
 755                         }
 756
 757                 } else
 758 #endif
 759                 {
 760                         siginfo_t __user *uinfo = (siginfo_t __user *) data;
 761
 762                         if (copy_siginfo_to_user(uinfo, &info)) {
 763                                 ret = -EFAULT;
 764                                 break;
 765                         }
 766                 }
 767
 768                 data += sizeof(siginfo_t);
 769                 i++;
 770
 771                 if (signal_pending(current))
 772                         break;
 773
 774                 cond_resched();
 775         }
 776
 777         if (i > 0)
 778                 return i;
 779
 780         return ret;
 781 }
 782
 783 #ifdef PTRACE_SINGLESTEP
 784 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 785 #else
 786 #define is_singlestep(request)          0
 787 #endif
 788
 789 #ifdef PTRACE_SINGLEBLOCK
 790 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 791 #else
 792 #define is_singleblock(request)         0
 793 #endif
 794
 795 #ifdef PTRACE_SYSEMU
 796 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 797 #else
 798 #define is_sysemu_singlestep(request)   0
 799 #endif
 800
 801 static int ptrace_resume(struct task_struct *child, long request,
 802                          unsigned long data)
 803 {
 804         bool need_siglock;
 805
 806         if (!valid_signal(data))
 807                 return -EIO;
 808
 809         if (request == PTRACE_SYSCALL)
 810                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 811         else
 812                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 813
 814 #ifdef TIF_SYSCALL_EMU
 815         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 816                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 817         else
 818                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 819 #endif
 820
 821         if (is_singleblock(request)) {
 822                 if (unlikely(!arch_has_block_step()))
 823                         return -EIO;
 824                 user_enable_block_step(child);
 825         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 826                 if (unlikely(!arch_has_single_step()))
 827                         return -EIO;
 828                 user_enable_single_step(child);
 829         } else {
 830                 user_disable_single_step(child);
 831         }
 832
 833         /*
 834          * Change ->exit_code and ->state under siglock to avoid the race
 835          * with wait_task_stopped() in between; a non-zero ->exit_code will
 836          * wrongly look like another report from tracee.
 837          *
 838          * Note that we need siglock even if ->exit_code == data and/or this
 839          * status was not reported yet, the new status must not be cleared by
 840          * wait_task_stopped() after resume.
 841          *
 842          * If data == 0 we do not care if wait_task_stopped() reports the old
 843          * status and clears the code too; this can't race with the tracee, it
 844          * takes siglock after resume.
 845          */
 846         need_siglock = data && !thread_group_empty(current);
 847         if (need_siglock)
 848                 spin_lock_irq(&child->sighand->siglock);
 849         child->exit_code = data;
 850         wake_up_state(child, __TASK_TRACED);
 851         if (need_siglock)
 852                 spin_unlock_irq(&child->sighand->siglock);
 853
 854         return 0;
 855 }
 856
 857 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 858
 859 static const struct user_regset *
 860 find_regset(const struct user_regset_view *view, unsigned int type)
 861 {
 862         const struct user_regset *regset;
 863         int n;
 864
 865         for (n = 0; n < view->n; ++n) {
 866                 regset = view->regsets + n;
 867                 if (regset->core_note_type == type)
 868                         return regset;
 869         }
 870
 871         return NULL;
 872 }
 873
 874 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 875                          struct iovec *kiov)
 876 {
 877         const struct user_regset_view *view = task_user_regset_view(task);
 878         const struct user_regset *regset = find_regset(view, type);
 879         int regset_no;
 880
 881         if (!regset || (kiov->iov_len % regset->size) != 0)
 882                 return -EINVAL;
 883
 884         regset_no = regset - view->regsets;
 885         kiov->iov_len = min(kiov->iov_len,
 886                             (__kernel_size_t) (regset->n * regset->size));
 887
 888         if (req == PTRACE_GETREGSET)
 889                 return copy_regset_to_user(task, view, regset_no, 0,
 890                                            kiov->iov_len, kiov->iov_base);
 891         else
 892                 return copy_regset_from_user(task, view, regset_no, 0,
 893                                              kiov->iov_len, kiov->iov_base);
 894 }
 895
 896 /*
 897  * This is declared in linux/regset.h and defined in machine-dependent
 898  * code.  We put the export here, near the primary machine-neutral use,
 899  * to ensure no machine forgets it.
 900  */
 901 EXPORT_SYMBOL_GPL(task_user_regset_view);
 902
 903 static unsigned long
 904 ptrace_get_syscall_info_entry(struct task_struct *child, struct pt_regs *regs,
 905                               struct ptrace_syscall_info *info)
 906 {
 907         unsigned long args[ARRAY_SIZE(info->entry.args)];
 908         int i;
 909
 910         info->op = PTRACE_SYSCALL_INFO_ENTRY;
 911         info->entry.nr = syscall_get_nr(child, regs);
 912         syscall_get_arguments(child, regs, args);
 913         for (i = 0; i < ARRAY_SIZE(args); i++)
 914                 info->entry.args[i] = args[i];
 915
 916         /* args is the last field in struct ptrace_syscall_info.entry */
 917         return offsetofend(struct ptrace_syscall_info, entry.args);
 918 }
 919
 920 static unsigned long
 921 ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs,
 922                                 struct ptrace_syscall_info *info)
 923 {
 924         /*
 925          * As struct ptrace_syscall_info.entry is currently a subset
 926          * of struct ptrace_syscall_info.seccomp, it makes sense to
 927          * initialize that subset using ptrace_get_syscall_info_entry().
 928          * This can be reconsidered in the future if these structures
 929          * diverge significantly enough.
 930          */
 931         ptrace_get_syscall_info_entry(child, regs, info);
 932         info->op = PTRACE_SYSCALL_INFO_SECCOMP;
 933         info->seccomp.ret_data = child->ptrace_message;
 934
 935         /* ret_data is the last field in struct ptrace_syscall_info.seccomp */
 936         return offsetofend(struct ptrace_syscall_info, seccomp.ret_data);
 937 }
 938
 939 static unsigned long
 940 ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs,
 941                              struct ptrace_syscall_info *info)
 942 {
 943         info->op = PTRACE_SYSCALL_INFO_EXIT;
 944         info->exit.rval = syscall_get_error(child, regs);
 945         info->exit.is_error = !!info->exit.rval;
 946         if (!info->exit.is_error)
 947                 info->exit.rval = syscall_get_return_value(child, regs);
 948
 949         /* is_error is the last field in struct ptrace_syscall_info.exit */
 950         return offsetofend(struct ptrace_syscall_info, exit.is_error);
 951 }
 952
 953 static int
 954 ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
 955                         void __user *datavp)
 956 {
 957         struct pt_regs *regs = task_pt_regs(child);
 958         struct ptrace_syscall_info info = {
 959                 .op = PTRACE_SYSCALL_INFO_NONE,
 960                 .arch = syscall_get_arch(child),
 961                 .instruction_pointer = instruction_pointer(regs),
 962                 .stack_pointer = user_stack_pointer(regs),
 963         };
 964         unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
 965         unsigned long write_size;
 966
 967         /*
 968          * This does not need lock_task_sighand() to access
 969          * child->last_siginfo because ptrace_freeze_traced()
 970          * called earlier by ptrace_check_attach() ensures that
 971          * the tracee cannot go away and clear its last_siginfo.
 972          */
 973         switch (child->last_siginfo ? child->last_siginfo->si_code : 0) {
 974         case SIGTRAP | 0x80:
 975                 switch (child->ptrace_message) {
 976                 case PTRACE_EVENTMSG_SYSCALL_ENTRY:
 977                         actual_size = ptrace_get_syscall_info_entry(child, regs,
 978                                                                     &info);
 979                         break;
 980                 case PTRACE_EVENTMSG_SYSCALL_EXIT:
 981                         actual_size = ptrace_get_syscall_info_exit(child, regs,
 982                                                                    &info);
 983                         break;
 984                 }
 985                 break;
 986         case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8):
 987                 actual_size = ptrace_get_syscall_info_seccomp(child, regs,
 988                                                               &info);
 989                 break;
 990         }
 991
 992         write_size = min(actual_size, user_size);
 993         return copy_to_user(datavp, &info, write_size) ? -EFAULT : actual_size;
 994 }
 995 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
 996
 997 int ptrace_request(struct task_struct *child, long request,
 998                    unsigned long addr, unsigned long data)
 999 {
1000         bool seized = child->ptrace & PT_SEIZED;
1001         int ret = -EIO;
1002         kernel_siginfo_t siginfo, *si;
1003         void __user *datavp = (void __user *) data;
1004         unsigned long __user *datalp = datavp;
1005         unsigned long flags;
1006
1007         switch (request) {
1008         case PTRACE_PEEKTEXT:
1009         case PTRACE_PEEKDATA:
1010                 return generic_ptrace_peekdata(child, addr, data);
1011         case PTRACE_POKETEXT:
1012         case PTRACE_POKEDATA:
1013                 return generic_ptrace_pokedata(child, addr, data);
1014
1015 #ifdef PTRACE_OLDSETOPTIONS
1016         case PTRACE_OLDSETOPTIONS:
1017 #endif
1018         case PTRACE_SETOPTIONS:
1019                 ret = ptrace_setoptions(child, data);
1020                 break;
1021         case PTRACE_GETEVENTMSG:
1022                 ret = put_user(child->ptrace_message, datalp);
1023                 break;
1024
1025         case PTRACE_PEEKSIGINFO:
1026                 ret = ptrace_peek_siginfo(child, addr, data);
1027                 break;
1028
1029         case PTRACE_GETSIGINFO:
1030                 ret = ptrace_getsiginfo(child, &siginfo);
1031                 if (!ret)
1032                         ret = copy_siginfo_to_user(datavp, &siginfo);
1033                 break;
1034
1035         case PTRACE_SETSIGINFO:
1036                 ret = copy_siginfo_from_user(&siginfo, datavp);
1037                 if (!ret)
1038                         ret = ptrace_setsiginfo(child, &siginfo);
1039                 break;
1040
1041         case PTRACE_GETSIGMASK: {
1042                 sigset_t *mask;
1043
1044                 if (addr != sizeof(sigset_t)) {
1045                         ret = -EINVAL;
1046                         break;
1047                 }
1048
1049                 if (test_tsk_restore_sigmask(child))
1050                         mask = &child->saved_sigmask;
1051                 else
1052                         mask = &child->blocked;
1053
1054                 if (copy_to_user(datavp, mask, sizeof(sigset_t)))
1055                         ret = -EFAULT;
1056                 else
1057                         ret = 0;
1058
1059                 break;
1060         }
1061
1062         case PTRACE_SETSIGMASK: {
1063                 sigset_t new_set;
1064
1065                 if (addr != sizeof(sigset_t)) {
1066                         ret = -EINVAL;
1067                         break;
1068                 }
1069
1070                 if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
1071                         ret = -EFAULT;
1072                         break;
1073                 }
1074
1075                 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
1076
1077                 /*
1078                  * Every thread does recalc_sigpending() after resume, so
1079                  * retarget_shared_pending() and recalc_sigpending() are not
1080                  * called here.
1081                  */
1082                 spin_lock_irq(&child->sighand->siglock);
1083                 child->blocked = new_set;
1084                 spin_unlock_irq(&child->sighand->siglock);
1085
1086                 clear_tsk_restore_sigmask(child);
1087
1088                 ret = 0;
1089                 break;
1090         }
1091
1092         case PTRACE_INTERRUPT:
1093                 /*
1094                  * Stop tracee without any side-effect on signal or job
1095                  * control.  At least one trap is guaranteed to happen
1096                  * after this request.  If @child is already trapped, the
1097                  * current trap is not disturbed and another trap will
1098                  * happen after the current trap is ended with PTRACE_CONT.
1099                  *
1100                  * The actual trap might not be PTRACE_EVENT_STOP trap but
1101                  * the pending condition is cleared regardless.
1102                  */
1103                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
1104                         break;
1105
1106                 /*
1107                  * INTERRUPT doesn't disturb existing trap sans one
1108                  * exception.  If ptracer issued LISTEN for the current
1109                  * STOP, this INTERRUPT should clear LISTEN and re-trap
1110                  * tracee into STOP.
1111                  */
1112                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
1113                         ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
1114
1115                 unlock_task_sighand(child, &flags);
1116                 ret = 0;
1117                 break;
1118
1119         case PTRACE_LISTEN:
1120                 /*
1121                  * Listen for events.  Tracee must be in STOP.  It's not
1122                  * resumed per-se but is not considered to be in TRACED by
1123                  * wait(2) or ptrace(2).  If an async event (e.g. group
1124                  * stop state change) happens, tracee will enter STOP trap
1125                  * again.  Alternatively, ptracer can issue INTERRUPT to
1126                  * finish listening and re-trap tracee into STOP.
1127                  */
1128                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
1129                         break;
1130
1131                 si = child->last_siginfo;
1132                 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
1133                         child->jobctl |= JOBCTL_LISTENING;
1134                         /*
1135                          * If NOTIFY is set, it means event happened between
1136                          * start of this trap and now.  Trigger re-trap.
1137                          */
1138                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
1139                                 ptrace_signal_wake_up(child, true);
1140                         ret = 0;
1141                 }
1142                 unlock_task_sighand(child, &flags);
1143                 break;
1144
1145         case PTRACE_DETACH:      /* detach a process that was attached. */
1146                 ret = ptrace_detach(child, data);
1147                 break;
1148
1149 #ifdef CONFIG_BINFMT_ELF_FDPIC
1150         case PTRACE_GETFDPIC: {
1151                 struct mm_struct *mm = get_task_mm(child);
1152                 unsigned long tmp = 0;
1153
1154                 ret = -ESRCH;
1155                 if (!mm)
1156                         break;
1157
1158                 switch (addr) {
1159                 case PTRACE_GETFDPIC_EXEC:
1160                         tmp = mm->context.exec_fdpic_loadmap;
1161                         break;
1162                 case PTRACE_GETFDPIC_INTERP:
1163                         tmp = mm->context.interp_fdpic_loadmap;
1164                         break;
1165                 default:
1166                         break;
1167                 }
1168                 mmput(mm);
1169
1170                 ret = put_user(tmp, datalp);
1171                 break;
1172         }
1173 #endif
1174
1175 #ifdef PTRACE_SINGLESTEP
1176         case PTRACE_SINGLESTEP:
1177 #endif
1178 #ifdef PTRACE_SINGLEBLOCK
1179         case PTRACE_SINGLEBLOCK:
1180 #endif
1181 #ifdef PTRACE_SYSEMU
1182         case PTRACE_SYSEMU:
1183         case PTRACE_SYSEMU_SINGLESTEP:
1184 #endif
1185         case PTRACE_SYSCALL:
1186         case PTRACE_CONT:
1187                 return ptrace_resume(child, request, data);
1188
1189         case PTRACE_KILL:
1190                 if (child->exit_state)  /* already dead */
1191                         return 0;
1192                 return ptrace_resume(child, request, SIGKILL);
1193
1194 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1195         case PTRACE_GETREGSET:
1196         case PTRACE_SETREGSET: {
1197                 struct iovec kiov;
1198                 struct iovec __user *uiov = datavp;
1199
1200                 if (!access_ok(uiov, sizeof(*uiov)))
1201                         return -EFAULT;
1202
1203                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
1204                     __get_user(kiov.iov_len, &uiov->iov_len))
1205                         return -EFAULT;
1206
1207                 ret = ptrace_regset(child, request, addr, &kiov);
1208                 if (!ret)
1209                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1210                 break;
1211         }
1212
1213         case PTRACE_GET_SYSCALL_INFO:
1214                 ret = ptrace_get_syscall_info(child, addr, datavp);
1215                 break;
1216 #endif
1217
1218         case PTRACE_SECCOMP_GET_FILTER:
1219                 ret = seccomp_get_filter(child, addr, datavp);
1220                 break;
1221
1222         case PTRACE_SECCOMP_GET_METADATA:
1223                 ret = seccomp_get_metadata(child, addr, datavp);
1224                 break;
1225
1226         default:
1227                 break;
1228         }
1229
1230         return ret;
1231 }
1232
1233 #ifndef arch_ptrace_attach
1234 #define arch_ptrace_attach(child)       do { } while (0)
1235 #endif
1236
1237 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1238                 unsigned long, data)
1239 {
1240         struct task_struct *child;
1241         long ret;
1242
1243         if (request == PTRACE_TRACEME) {
1244                 ret = ptrace_traceme();
1245                 if (!ret)
1246                         arch_ptrace_attach(current);
1247                 goto out;
1248         }
1249
1250         child = find_get_task_by_vpid(pid);
1251         if (!child) {
1252                 ret = -ESRCH;
1253                 goto out;
1254         }
1255
1256         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1257                 ret = ptrace_attach(child, request, addr, data);
1258                 /*
1259                  * Some architectures need to do book-keeping after
1260                  * a ptrace attach.
1261                  */
1262                 if (!ret)
1263                         arch_ptrace_attach(child);
1264                 goto out_put_task_struct;
1265         }
1266
1267         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1268                                   request == PTRACE_INTERRUPT);
1269         if (ret < 0)
1270                 goto out_put_task_struct;
1271
1272         ret = arch_ptrace(child, request, addr, data);
1273         if (ret || request != PTRACE_DETACH)
1274                 ptrace_unfreeze_traced(child);
1275
1276  out_put_task_struct:
1277         put_task_struct(child);
1278  out:
1279         return ret;
1280 }
1281
1282 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1283                             unsigned long data)
1284 {
1285         unsigned long tmp;
1286         int copied;
1287
1288         copied = ptrace_access_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE);
1289         if (copied != sizeof(tmp))
1290                 return -EIO;
1291         return put_user(tmp, (unsigned long __user *)data);
1292 }
1293
1294 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1295                             unsigned long data)
1296 {
1297         int copied;
1298
1299         copied = ptrace_access_vm(tsk, addr, &data, sizeof(data),
1300                         FOLL_FORCE | FOLL_WRITE);
1301         return (copied == sizeof(data)) ? 0 : -EIO;
1302 }
1303
1304 #if defined CONFIG_COMPAT
1305
1306 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1307                           compat_ulong_t addr, compat_ulong_t data)
1308 {
1309         compat_ulong_t __user *datap = compat_ptr(data);
1310         compat_ulong_t word;
1311         kernel_siginfo_t siginfo;
1312         int ret;
1313
1314         switch (request) {
1315         case PTRACE_PEEKTEXT:
1316         case PTRACE_PEEKDATA:
1317                 ret = ptrace_access_vm(child, addr, &word, sizeof(word),
1318                                 FOLL_FORCE);
1319                 if (ret != sizeof(word))
1320                         ret = -EIO;
1321                 else
1322                         ret = put_user(word, datap);
1323                 break;
1324
1325         case PTRACE_POKETEXT:
1326         case PTRACE_POKEDATA:
1327                 ret = ptrace_access_vm(child, addr, &data, sizeof(data),
1328                                 FOLL_FORCE | FOLL_WRITE);
1329                 ret = (ret != sizeof(data) ? -EIO : 0);
1330                 break;
1331
1332         case PTRACE_GETEVENTMSG:
1333                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1334                 break;
1335
1336         case PTRACE_GETSIGINFO:
1337                 ret = ptrace_getsiginfo(child, &siginfo);
1338                 if (!ret)
1339                         ret = copy_siginfo_to_user32(
1340                                 (struct compat_siginfo __user *) datap,
1341                                 &siginfo);
1342                 break;
1343
1344         case PTRACE_SETSIGINFO:
1345                 ret = copy_siginfo_from_user32(
1346                         &siginfo, (struct compat_siginfo __user *) datap);
1347                 if (!ret)
1348                         ret = ptrace_setsiginfo(child, &siginfo);
1349                 break;
1350 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1351         case PTRACE_GETREGSET:
1352         case PTRACE_SETREGSET:
1353         {
1354                 struct iovec kiov;
1355                 struct compat_iovec __user *uiov =
1356                         (struct compat_iovec __user *) datap;
1357                 compat_uptr_t ptr;
1358                 compat_size_t len;
1359
1360                 if (!access_ok(uiov, sizeof(*uiov)))
1361                         return -EFAULT;
1362
1363                 if (__get_user(ptr, &uiov->iov_base) ||
1364                     __get_user(len, &uiov->iov_len))
1365                         return -EFAULT;
1366
1367                 kiov.iov_base = compat_ptr(ptr);
1368                 kiov.iov_len = len;
1369
1370                 ret = ptrace_regset(child, request, addr, &kiov);
1371                 if (!ret)
1372                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1373                 break;
1374         }
1375 #endif
1376
1377         default:
1378                 ret = ptrace_request(child, request, addr, data);
1379         }
1380
1381         return ret;
1382 }
1383
1384 COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1385                        compat_long_t, addr, compat_long_t, data)
1386 {
1387         struct task_struct *child;
1388         long ret;
1389
1390         if (request == PTRACE_TRACEME) {
1391                 ret = ptrace_traceme();
1392                 goto out;
1393         }
1394
1395         child = find_get_task_by_vpid(pid);
1396         if (!child) {
1397                 ret = -ESRCH;
1398                 goto out;
1399         }
1400
1401         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1402                 ret = ptrace_attach(child, request, addr, data);
1403                 /*
1404                  * Some architectures need to do book-keeping after
1405                  * a ptrace attach.
1406                  */
1407                 if (!ret)
1408                         arch_ptrace_attach(child);
1409                 goto out_put_task_struct;
1410         }
1411
1412         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1413                                   request == PTRACE_INTERRUPT);
1414         if (!ret) {
1415                 ret = compat_arch_ptrace(child, request, addr, data);
1416                 if (ret || request != PTRACE_DETACH)
1417                         ptrace_unfreeze_traced(child);
1418         }
1419
1420  out_put_task_struct:
1421         put_task_struct(child);
1422  out:
1423         return ret;
1424 }
1425 #endif  /* CONFIG_COMPAT */