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/uio.h>
  21 #include <linux/audit.h>
  22 #include <linux/pid_namespace.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/regset.h>
  26 #include <linux/hw_breakpoint.h>
  27 #include <linux/cn_proc.h>
  28 #include <linux/compat.h>
  29
  30
  31 /*
  32  * ptrace a task: make the debugger its new parent and
  33  * move it to the ptrace list.
  34  *
  35  * Must be called with the tasklist lock write-held.
  36  */
  37 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  38 {
  39         BUG_ON(!list_empty(&child->ptrace_entry));
  40         list_add(&child->ptrace_entry, &new_parent->ptraced);
  41         child->parent = new_parent;
  42 }
  43
  44 /**
  45  * __ptrace_unlink - unlink ptracee and restore its execution state
  46  * @child: ptracee to be unlinked
  47  *
  48  * Remove @child from the ptrace list, move it back to the original parent,
  49  * and restore the execution state so that it conforms to the group stop
  50  * state.
  51  *
  52  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  53  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  54  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  55  * If the ptracer is exiting, the ptracee can be in any state.
  56  *
  57  * After detach, the ptracee should be in a state which conforms to the
  58  * group stop.  If the group is stopped or in the process of stopping, the
  59  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  60  * up from TASK_TRACED.
  61  *
  62  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  63  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  64  * to but in the opposite direction of what happens while attaching to a
  65  * stopped task.  However, in this direction, the intermediate RUNNING
  66  * state is not hidden even from the current ptracer and if it immediately
  67  * re-attaches and performs a WNOHANG wait(2), it may fail.
  68  *
  69  * CONTEXT:
  70  * write_lock_irq(tasklist_lock)
  71  */
  72 void __ptrace_unlink(struct task_struct *child)
  73 {
  74         BUG_ON(!child->ptrace);
  75
  76         child->ptrace = 0;
  77         child->parent = child->real_parent;
  78         list_del_init(&child->ptrace_entry);
  79
  80         spin_lock(&child->sighand->siglock);
  81
  82         /*
  83          * Clear all pending traps and TRAPPING.  TRAPPING should be
  84          * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
  85          */
  86         task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
  87         task_clear_jobctl_trapping(child);
  88
  89         /*
  90          * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
  91          * @child isn't dead.
  92          */
  93         if (!(child->flags & PF_EXITING) &&
  94             (child->signal->flags & SIGNAL_STOP_STOPPED ||
  95              child->signal->group_stop_count)) {
  96                 child->jobctl |= JOBCTL_STOP_PENDING;
  97
  98                 /*
  99                  * This is only possible if this thread was cloned by the
 100                  * traced task running in the stopped group, set the signal
 101                  * for the future reports.
 102                  * FIXME: we should change ptrace_init_task() to handle this
 103                  * case.
 104                  */
 105                 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
 106                         child->jobctl |= SIGSTOP;
 107         }
 108
 109         /*
 110          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
 111          * @child in the butt.  Note that @resume should be used iff @child
 112          * is in TASK_TRACED; otherwise, we might unduly disrupt
 113          * TASK_KILLABLE sleeps.
 114          */
 115         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
 116                 ptrace_signal_wake_up(child, true);
 117
 118         spin_unlock(&child->sighand->siglock);
 119 }
 120
 121 /* Ensure that nothing can wake it up, even SIGKILL */
 122 static bool ptrace_freeze_traced(struct task_struct *task)
 123 {
 124         bool ret = false;
 125
 126         /* Lockless, nobody but us can set this flag */
 127         if (task->jobctl & JOBCTL_LISTENING)
 128                 return ret;
 129
 130         spin_lock_irq(&task->sighand->siglock);
 131         if (task_is_traced(task) && !__fatal_signal_pending(task)) {
 132                 task->state = __TASK_TRACED;
 133                 ret = true;
 134         }
 135         spin_unlock_irq(&task->sighand->siglock);
 136
 137         return ret;
 138 }
 139
 140 static void ptrace_unfreeze_traced(struct task_struct *task)
 141 {
 142         if (task->state != __TASK_TRACED)
 143                 return;
 144
 145         WARN_ON(!task->ptrace || task->parent != current);
 146
 147         spin_lock_irq(&task->sighand->siglock);
 148         if (__fatal_signal_pending(task))
 149                 wake_up_state(task, __TASK_TRACED);
 150         else
 151                 task->state = TASK_TRACED;
 152         spin_unlock_irq(&task->sighand->siglock);
 153 }
 154
 155 /**
 156  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
 157  * @child: ptracee to check for
 158  * @ignore_state: don't check whether @child is currently %TASK_TRACED
 159  *
 160  * Check whether @child is being ptraced by %current and ready for further
 161  * ptrace operations.  If @ignore_state is %false, @child also should be in
 162  * %TASK_TRACED state and on return the child is guaranteed to be traced
 163  * and not executing.  If @ignore_state is %true, @child can be in any
 164  * state.
 165  *
 166  * CONTEXT:
 167  * Grabs and releases tasklist_lock and @child->sighand->siglock.
 168  *
 169  * RETURNS:
 170  * 0 on success, -ESRCH if %child is not ready.
 171  */
 172 static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 173 {
 174         int ret = -ESRCH;
 175
 176         /*
 177          * We take the read lock around doing both checks to close a
 178          * possible race where someone else was tracing our child and
 179          * detached between these two checks.  After this locked check,
 180          * we are sure that this is our traced child and that can only
 181          * be changed by us so it's not changing right after this.
 182          */
 183         read_lock(&tasklist_lock);
 184         if (child->ptrace && child->parent == current) {
 185                 WARN_ON(child->state == __TASK_TRACED);
 186                 /*
 187                  * child->sighand can't be NULL, release_task()
 188                  * does ptrace_unlink() before __exit_signal().
 189                  */
 190                 if (ignore_state || ptrace_freeze_traced(child))
 191                         ret = 0;
 192         }
 193         read_unlock(&tasklist_lock);
 194
 195         if (!ret && !ignore_state) {
 196                 if (!wait_task_inactive(child, __TASK_TRACED)) {
 197                         /*
 198                          * This can only happen if may_ptrace_stop() fails and
 199                          * ptrace_stop() changes ->state back to TASK_RUNNING,
 200                          * so we should not worry about leaking __TASK_TRACED.
 201                          */
 202                         WARN_ON(child->state == __TASK_TRACED);
 203                         ret = -ESRCH;
 204                 }
 205         }
 206
 207         return ret;
 208 }
 209
 210 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 211 {
 212         if (mode & PTRACE_MODE_NOAUDIT)
 213                 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
 214         else
 215                 return has_ns_capability(current, ns, CAP_SYS_PTRACE);
 216 }
 217
 218 /* Returns 0 on success, -errno on denial. */
 219 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 220 {
 221         const struct cred *cred = current_cred(), *tcred;
 222
 223         /* May we inspect the given task?
 224          * This check is used both for attaching with ptrace
 225          * and for allowing access to sensitive information in /proc.
 226          *
 227          * ptrace_attach denies several cases that /proc allows
 228          * because setting up the necessary parent/child relationship
 229          * or halting the specified task is impossible.
 230          */
 231         int dumpable = 0;
 232         /* Don't let security modules deny introspection */
 233         if (same_thread_group(task, current))
 234                 return 0;
 235         rcu_read_lock();
 236         tcred = __task_cred(task);
 237         if (uid_eq(cred->uid, tcred->euid) &&
 238             uid_eq(cred->uid, tcred->suid) &&
 239             uid_eq(cred->uid, tcred->uid)  &&
 240             gid_eq(cred->gid, tcred->egid) &&
 241             gid_eq(cred->gid, tcred->sgid) &&
 242             gid_eq(cred->gid, tcred->gid))
 243                 goto ok;
 244         if (ptrace_has_cap(tcred->user_ns, mode))
 245                 goto ok;
 246         rcu_read_unlock();
 247         return -EPERM;
 248 ok:
 249         rcu_read_unlock();
 250         smp_rmb();
 251         if (task->mm)
 252                 dumpable = get_dumpable(task->mm);
 253         rcu_read_lock();
 254         if (dumpable != SUID_DUMP_USER &&
 255             !ptrace_has_cap(__task_cred(task)->user_ns, mode)) {
 256                 rcu_read_unlock();
 257                 return -EPERM;
 258         }
 259         rcu_read_unlock();
 260
 261         return security_ptrace_access_check(task, mode);
 262 }
 263
 264 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 265 {
 266         int err;
 267         task_lock(task);
 268         err = __ptrace_may_access(task, mode);
 269         task_unlock(task);
 270         return !err;
 271 }
 272
 273 static int ptrace_attach(struct task_struct *task, long request,
 274                          unsigned long addr,
 275                          unsigned long flags)
 276 {
 277         bool seize = (request == PTRACE_SEIZE);
 278         int retval;
 279
 280         retval = -EIO;
 281         if (seize) {
 282                 if (addr != 0)
 283                         goto out;
 284                 if (flags & ~(unsigned long)PTRACE_O_MASK)
 285                         goto out;
 286                 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
 287         } else {
 288                 flags = PT_PTRACED;
 289         }
 290
 291         audit_ptrace(task);
 292
 293         retval = -EPERM;
 294         if (unlikely(task->flags & PF_KTHREAD))
 295                 goto out;
 296         if (same_thread_group(task, current))
 297                 goto out;
 298
 299         /*
 300          * Protect exec's credential calculations against our interference;
 301          * SUID, SGID and LSM creds get determined differently
 302          * under ptrace.
 303          */
 304         retval = -ERESTARTNOINTR;
 305         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 306                 goto out;
 307
 308         task_lock(task);
 309         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 310         task_unlock(task);
 311         if (retval)
 312                 goto unlock_creds;
 313
 314         write_lock_irq(&tasklist_lock);
 315         retval = -EPERM;
 316         if (unlikely(task->exit_state))
 317                 goto unlock_tasklist;
 318         if (task->ptrace)
 319                 goto unlock_tasklist;
 320
 321         if (seize)
 322                 flags |= PT_SEIZED;
 323         rcu_read_lock();
 324         if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE))
 325                 flags |= PT_PTRACE_CAP;
 326         rcu_read_unlock();
 327         task->ptrace = flags;
 328
 329         __ptrace_link(task, current);
 330
 331         /* SEIZE doesn't trap tracee on attach */
 332         if (!seize)
 333                 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 334
 335         spin_lock(&task->sighand->siglock);
 336
 337         /*
 338          * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
 339          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 340          * will be cleared if the child completes the transition or any
 341          * event which clears the group stop states happens.  We'll wait
 342          * for the transition to complete before returning from this
 343          * function.
 344          *
 345          * This hides STOPPED -> RUNNING -> TRACED transition from the
 346          * attaching thread but a different thread in the same group can
 347          * still observe the transient RUNNING state.  IOW, if another
 348          * thread's WNOHANG wait(2) on the stopped tracee races against
 349          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 350          *
 351          * The following task_is_stopped() test is safe as both transitions
 352          * in and out of STOPPED are protected by siglock.
 353          */
 354         if (task_is_stopped(task) &&
 355             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
 356                 signal_wake_up_state(task, __TASK_STOPPED);
 357
 358         spin_unlock(&task->sighand->siglock);
 359
 360         retval = 0;
 361 unlock_tasklist:
 362         write_unlock_irq(&tasklist_lock);
 363 unlock_creds:
 364         mutex_unlock(&task->signal->cred_guard_mutex);
 365 out:
 366         if (!retval) {
 367                 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
 368                             TASK_UNINTERRUPTIBLE);
 369                 proc_ptrace_connector(task, PTRACE_ATTACH);
 370         }
 371
 372         return retval;
 373 }
 374
 375 /**
 376  * ptrace_traceme  --  helper for PTRACE_TRACEME
 377  *
 378  * Performs checks and sets PT_PTRACED.
 379  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 380  */
 381 static int ptrace_traceme(void)
 382 {
 383         int ret = -EPERM;
 384
 385         write_lock_irq(&tasklist_lock);
 386         /* Are we already being traced? */
 387         if (!current->ptrace) {
 388                 ret = security_ptrace_traceme(current->parent);
 389                 /*
 390                  * Check PF_EXITING to ensure ->real_parent has not passed
 391                  * exit_ptrace(). Otherwise we don't report the error but
 392                  * pretend ->real_parent untraces us right after return.
 393                  */
 394                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 395                         current->ptrace = PT_PTRACED;
 396                         __ptrace_link(current, current->real_parent);
 397                 }
 398         }
 399         write_unlock_irq(&tasklist_lock);
 400
 401         return ret;
 402 }
 403
 404 /*
 405  * Called with irqs disabled, returns true if childs should reap themselves.
 406  */
 407 static int ignoring_children(struct sighand_struct *sigh)
 408 {
 409         int ret;
 410         spin_lock(&sigh->siglock);
 411         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 412               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 413         spin_unlock(&sigh->siglock);
 414         return ret;
 415 }
 416
 417 /*
 418  * Called with tasklist_lock held for writing.
 419  * Unlink a traced task, and clean it up if it was a traced zombie.
 420  * Return true if it needs to be reaped with release_task().
 421  * (We can't call release_task() here because we already hold tasklist_lock.)
 422  *
 423  * If it's a zombie, our attachedness prevented normal parent notification
 424  * or self-reaping.  Do notification now if it would have happened earlier.
 425  * If it should reap itself, return true.
 426  *
 427  * If it's our own child, there is no notification to do. But if our normal
 428  * children self-reap, then this child was prevented by ptrace and we must
 429  * reap it now, in that case we must also wake up sub-threads sleeping in
 430  * do_wait().
 431  */
 432 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 433 {
 434         bool dead;
 435
 436         __ptrace_unlink(p);
 437
 438         if (p->exit_state != EXIT_ZOMBIE)
 439                 return false;
 440
 441         dead = !thread_group_leader(p);
 442
 443         if (!dead && thread_group_empty(p)) {
 444                 if (!same_thread_group(p->real_parent, tracer))
 445                         dead = do_notify_parent(p, p->exit_signal);
 446                 else if (ignoring_children(tracer->sighand)) {
 447                         __wake_up_parent(p, tracer);
 448                         dead = true;
 449                 }
 450         }
 451         /* Mark it as in the process of being reaped. */
 452         if (dead)
 453                 p->exit_state = EXIT_DEAD;
 454         return dead;
 455 }
 456
 457 static int ptrace_detach(struct task_struct *child, unsigned int data)
 458 {
 459         if (!valid_signal(data))
 460                 return -EIO;
 461
 462         /* Architecture-specific hardware disable .. */
 463         ptrace_disable(child);
 464         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 465
 466         write_lock_irq(&tasklist_lock);
 467         /*
 468          * We rely on ptrace_freeze_traced(). It can't be killed and
 469          * untraced by another thread, it can't be a zombie.
 470          */
 471         WARN_ON(!child->ptrace || child->exit_state);
 472         /*
 473          * tasklist_lock avoids the race with wait_task_stopped(), see
 474          * the comment in ptrace_resume().
 475          */
 476         child->exit_code = data;
 477         __ptrace_detach(current, child);
 478         write_unlock_irq(&tasklist_lock);
 479
 480         proc_ptrace_connector(child, PTRACE_DETACH);
 481
 482         return 0;
 483 }
 484
 485 /*
 486  * Detach all tasks we were using ptrace on. Called with tasklist held
 487  * for writing.
 488  */
 489 void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
 490 {
 491         struct task_struct *p, *n;
 492
 493         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 494                 if (unlikely(p->ptrace & PT_EXITKILL))
 495                         send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
 496
 497                 if (__ptrace_detach(tracer, p))
 498                         list_add(&p->ptrace_entry, dead);
 499         }
 500 }
 501
 502 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 503 {
 504         int copied = 0;
 505
 506         while (len > 0) {
 507                 char buf[128];
 508                 int this_len, retval;
 509
 510                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 511                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 512                 if (!retval) {
 513                         if (copied)
 514                                 break;
 515                         return -EIO;
 516                 }
 517                 if (copy_to_user(dst, buf, retval))
 518                         return -EFAULT;
 519                 copied += retval;
 520                 src += retval;
 521                 dst += retval;
 522                 len -= retval;
 523         }
 524         return copied;
 525 }
 526
 527 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 528 {
 529         int copied = 0;
 530
 531         while (len > 0) {
 532                 char buf[128];
 533                 int this_len, retval;
 534
 535                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 536                 if (copy_from_user(buf, src, this_len))
 537                         return -EFAULT;
 538                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 539                 if (!retval) {
 540                         if (copied)
 541                                 break;
 542                         return -EIO;
 543                 }
 544                 copied += retval;
 545                 src += retval;
 546                 dst += retval;
 547                 len -= retval;
 548         }
 549         return copied;
 550 }
 551
 552 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 553 {
 554         unsigned flags;
 555
 556         if (data & ~(unsigned long)PTRACE_O_MASK)
 557                 return -EINVAL;
 558
 559         /* Avoid intermediate state when all opts are cleared */
 560         flags = child->ptrace;
 561         flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
 562         flags |= (data << PT_OPT_FLAG_SHIFT);
 563         child->ptrace = flags;
 564
 565         return 0;
 566 }
 567
 568 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 569 {
 570         unsigned long flags;
 571         int error = -ESRCH;
 572
 573         if (lock_task_sighand(child, &flags)) {
 574                 error = -EINVAL;
 575                 if (likely(child->last_siginfo != NULL)) {
 576                         *info = *child->last_siginfo;
 577                         error = 0;
 578                 }
 579                 unlock_task_sighand(child, &flags);
 580         }
 581         return error;
 582 }
 583
 584 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 585 {
 586         unsigned long flags;
 587         int error = -ESRCH;
 588
 589         if (lock_task_sighand(child, &flags)) {
 590                 error = -EINVAL;
 591                 if (likely(child->last_siginfo != NULL)) {
 592                         *child->last_siginfo = *info;
 593                         error = 0;
 594                 }
 595                 unlock_task_sighand(child, &flags);
 596         }
 597         return error;
 598 }
 599
 600 static int ptrace_peek_siginfo(struct task_struct *child,
 601                                 unsigned long addr,
 602                                 unsigned long data)
 603 {
 604         struct ptrace_peeksiginfo_args arg;
 605         struct sigpending *pending;
 606         struct sigqueue *q;
 607         int ret, i;
 608
 609         ret = copy_from_user(&arg, (void __user *) addr,
 610                                 sizeof(struct ptrace_peeksiginfo_args));
 611         if (ret)
 612                 return -EFAULT;
 613
 614         if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
 615                 return -EINVAL; /* unknown flags */
 616
 617         if (arg.nr < 0)
 618                 return -EINVAL;
 619
 620         if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
 621                 pending = &child->signal->shared_pending;
 622         else
 623                 pending = &child->pending;
 624
 625         for (i = 0; i < arg.nr; ) {
 626                 siginfo_t info;
 627                 s32 off = arg.off + i;
 628
 629                 spin_lock_irq(&child->sighand->siglock);
 630                 list_for_each_entry(q, &pending->list, list) {
 631                         if (!off--) {
 632                                 copy_siginfo(&info, &q->info);
 633                                 break;
 634                         }
 635                 }
 636                 spin_unlock_irq(&child->sighand->siglock);
 637
 638                 if (off >= 0) /* beyond the end of the list */
 639                         break;
 640
 641 #ifdef CONFIG_COMPAT
 642                 if (unlikely(is_compat_task())) {
 643                         compat_siginfo_t __user *uinfo = compat_ptr(data);
 644
 645                         if (copy_siginfo_to_user32(uinfo, &info) ||
 646                             __put_user(info.si_code, &uinfo->si_code)) {
 647                                 ret = -EFAULT;
 648                                 break;
 649                         }
 650
 651                 } else
 652 #endif
 653                 {
 654                         siginfo_t __user *uinfo = (siginfo_t __user *) data;
 655
 656                         if (copy_siginfo_to_user(uinfo, &info) ||
 657                             __put_user(info.si_code, &uinfo->si_code)) {
 658                                 ret = -EFAULT;
 659                                 break;
 660                         }
 661                 }
 662
 663                 data += sizeof(siginfo_t);
 664                 i++;
 665
 666                 if (signal_pending(current))
 667                         break;
 668
 669                 cond_resched();
 670         }
 671
 672         if (i > 0)
 673                 return i;
 674
 675         return ret;
 676 }
 677
 678 #ifdef PTRACE_SINGLESTEP
 679 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 680 #else
 681 #define is_singlestep(request)          0
 682 #endif
 683
 684 #ifdef PTRACE_SINGLEBLOCK
 685 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 686 #else
 687 #define is_singleblock(request)         0
 688 #endif
 689
 690 #ifdef PTRACE_SYSEMU
 691 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 692 #else
 693 #define is_sysemu_singlestep(request)   0
 694 #endif
 695
 696 static int ptrace_resume(struct task_struct *child, long request,
 697                          unsigned long data)
 698 {
 699         bool need_siglock;
 700
 701         if (!valid_signal(data))
 702                 return -EIO;
 703
 704         if (request == PTRACE_SYSCALL)
 705                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 706         else
 707                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 708
 709 #ifdef TIF_SYSCALL_EMU
 710         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 711                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 712         else
 713                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 714 #endif
 715
 716         if (is_singleblock(request)) {
 717                 if (unlikely(!arch_has_block_step()))
 718                         return -EIO;
 719                 user_enable_block_step(child);
 720         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 721                 if (unlikely(!arch_has_single_step()))
 722                         return -EIO;
 723                 user_enable_single_step(child);
 724         } else {
 725                 user_disable_single_step(child);
 726         }
 727
 728         /*
 729          * Change ->exit_code and ->state under siglock to avoid the race
 730          * with wait_task_stopped() in between; a non-zero ->exit_code will
 731          * wrongly look like another report from tracee.
 732          *
 733          * Note that we need siglock even if ->exit_code == data and/or this
 734          * status was not reported yet, the new status must not be cleared by
 735          * wait_task_stopped() after resume.
 736          *
 737          * If data == 0 we do not care if wait_task_stopped() reports the old
 738          * status and clears the code too; this can't race with the tracee, it
 739          * takes siglock after resume.
 740          */
 741         need_siglock = data && !thread_group_empty(current);
 742         if (need_siglock)
 743                 spin_lock_irq(&child->sighand->siglock);
 744         child->exit_code = data;
 745         wake_up_state(child, __TASK_TRACED);
 746         if (need_siglock)
 747                 spin_unlock_irq(&child->sighand->siglock);
 748
 749         return 0;
 750 }
 751
 752 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 753
 754 static const struct user_regset *
 755 find_regset(const struct user_regset_view *view, unsigned int type)
 756 {
 757         const struct user_regset *regset;
 758         int n;
 759
 760         for (n = 0; n < view->n; ++n) {
 761                 regset = view->regsets + n;
 762                 if (regset->core_note_type == type)
 763                         return regset;
 764         }
 765
 766         return NULL;
 767 }
 768
 769 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 770                          struct iovec *kiov)
 771 {
 772         const struct user_regset_view *view = task_user_regset_view(task);
 773         const struct user_regset *regset = find_regset(view, type);
 774         int regset_no;
 775
 776         if (!regset || (kiov->iov_len % regset->size) != 0)
 777                 return -EINVAL;
 778
 779         regset_no = regset - view->regsets;
 780         kiov->iov_len = min(kiov->iov_len,
 781                             (__kernel_size_t) (regset->n * regset->size));
 782
 783         if (req == PTRACE_GETREGSET)
 784                 return copy_regset_to_user(task, view, regset_no, 0,
 785                                            kiov->iov_len, kiov->iov_base);
 786         else
 787                 return copy_regset_from_user(task, view, regset_no, 0,
 788                                              kiov->iov_len, kiov->iov_base);
 789 }
 790
 791 /*
 792  * This is declared in linux/regset.h and defined in machine-dependent
 793  * code.  We put the export here, near the primary machine-neutral use,
 794  * to ensure no machine forgets it.
 795  */
 796 EXPORT_SYMBOL_GPL(task_user_regset_view);
 797 #endif
 798
 799 int ptrace_request(struct task_struct *child, long request,
 800                    unsigned long addr, unsigned long data)
 801 {
 802         bool seized = child->ptrace & PT_SEIZED;
 803         int ret = -EIO;
 804         siginfo_t siginfo, *si;
 805         void __user *datavp = (void __user *) data;
 806         unsigned long __user *datalp = datavp;
 807         unsigned long flags;
 808
 809         switch (request) {
 810         case PTRACE_PEEKTEXT:
 811         case PTRACE_PEEKDATA:
 812                 return generic_ptrace_peekdata(child, addr, data);
 813         case PTRACE_POKETEXT:
 814         case PTRACE_POKEDATA:
 815                 return generic_ptrace_pokedata(child, addr, data);
 816
 817 #ifdef PTRACE_OLDSETOPTIONS
 818         case PTRACE_OLDSETOPTIONS:
 819 #endif
 820         case PTRACE_SETOPTIONS:
 821                 ret = ptrace_setoptions(child, data);
 822                 break;
 823         case PTRACE_GETEVENTMSG:
 824                 ret = put_user(child->ptrace_message, datalp);
 825                 break;
 826
 827         case PTRACE_PEEKSIGINFO:
 828                 ret = ptrace_peek_siginfo(child, addr, data);
 829                 break;
 830
 831         case PTRACE_GETSIGINFO:
 832                 ret = ptrace_getsiginfo(child, &siginfo);
 833                 if (!ret)
 834                         ret = copy_siginfo_to_user(datavp, &siginfo);
 835                 break;
 836
 837         case PTRACE_SETSIGINFO:
 838                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 839                         ret = -EFAULT;
 840                 else
 841                         ret = ptrace_setsiginfo(child, &siginfo);
 842                 break;
 843
 844         case PTRACE_GETSIGMASK:
 845                 if (addr != sizeof(sigset_t)) {
 846                         ret = -EINVAL;
 847                         break;
 848                 }
 849
 850                 if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t)))
 851                         ret = -EFAULT;
 852                 else
 853                         ret = 0;
 854
 855                 break;
 856
 857         case PTRACE_SETSIGMASK: {
 858                 sigset_t new_set;
 859
 860                 if (addr != sizeof(sigset_t)) {
 861                         ret = -EINVAL;
 862                         break;
 863                 }
 864
 865                 if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) {
 866                         ret = -EFAULT;
 867                         break;
 868                 }
 869
 870                 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
 871
 872                 /*
 873                  * Every thread does recalc_sigpending() after resume, so
 874                  * retarget_shared_pending() and recalc_sigpending() are not
 875                  * called here.
 876                  */
 877                 spin_lock_irq(&child->sighand->siglock);
 878                 child->blocked = new_set;
 879                 spin_unlock_irq(&child->sighand->siglock);
 880
 881                 ret = 0;
 882                 break;
 883         }
 884
 885         case PTRACE_INTERRUPT:
 886                 /*
 887                  * Stop tracee without any side-effect on signal or job
 888                  * control.  At least one trap is guaranteed to happen
 889                  * after this request.  If @child is already trapped, the
 890                  * current trap is not disturbed and another trap will
 891                  * happen after the current trap is ended with PTRACE_CONT.
 892                  *
 893                  * The actual trap might not be PTRACE_EVENT_STOP trap but
 894                  * the pending condition is cleared regardless.
 895                  */
 896                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 897                         break;
 898
 899                 /*
 900                  * INTERRUPT doesn't disturb existing trap sans one
 901                  * exception.  If ptracer issued LISTEN for the current
 902                  * STOP, this INTERRUPT should clear LISTEN and re-trap
 903                  * tracee into STOP.
 904                  */
 905                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
 906                         ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
 907
 908                 unlock_task_sighand(child, &flags);
 909                 ret = 0;
 910                 break;
 911
 912         case PTRACE_LISTEN:
 913                 /*
 914                  * Listen for events.  Tracee must be in STOP.  It's not
 915                  * resumed per-se but is not considered to be in TRACED by
 916                  * wait(2) or ptrace(2).  If an async event (e.g. group
 917                  * stop state change) happens, tracee will enter STOP trap
 918                  * again.  Alternatively, ptracer can issue INTERRUPT to
 919                  * finish listening and re-trap tracee into STOP.
 920                  */
 921                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 922                         break;
 923
 924                 si = child->last_siginfo;
 925                 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
 926                         child->jobctl |= JOBCTL_LISTENING;
 927                         /*
 928                          * If NOTIFY is set, it means event happened between
 929                          * start of this trap and now.  Trigger re-trap.
 930                          */
 931                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
 932                                 ptrace_signal_wake_up(child, true);
 933                         ret = 0;
 934                 }
 935                 unlock_task_sighand(child, &flags);
 936                 break;
 937
 938         case PTRACE_DETACH:      /* detach a process that was attached. */
 939                 ret = ptrace_detach(child, data);
 940                 break;
 941
 942 #ifdef CONFIG_BINFMT_ELF_FDPIC
 943         case PTRACE_GETFDPIC: {
 944                 struct mm_struct *mm = get_task_mm(child);
 945                 unsigned long tmp = 0;
 946
 947                 ret = -ESRCH;
 948                 if (!mm)
 949                         break;
 950
 951                 switch (addr) {
 952                 case PTRACE_GETFDPIC_EXEC:
 953                         tmp = mm->context.exec_fdpic_loadmap;
 954                         break;
 955                 case PTRACE_GETFDPIC_INTERP:
 956                         tmp = mm->context.interp_fdpic_loadmap;
 957                         break;
 958                 default:
 959                         break;
 960                 }
 961                 mmput(mm);
 962
 963                 ret = put_user(tmp, datalp);
 964                 break;
 965         }
 966 #endif
 967
 968 #ifdef PTRACE_SINGLESTEP
 969         case PTRACE_SINGLESTEP:
 970 #endif
 971 #ifdef PTRACE_SINGLEBLOCK
 972         case PTRACE_SINGLEBLOCK:
 973 #endif
 974 #ifdef PTRACE_SYSEMU
 975         case PTRACE_SYSEMU:
 976         case PTRACE_SYSEMU_SINGLESTEP:
 977 #endif
 978         case PTRACE_SYSCALL:
 979         case PTRACE_CONT:
 980                 return ptrace_resume(child, request, data);
 981
 982         case PTRACE_KILL:
 983                 if (child->exit_state)  /* already dead */
 984                         return 0;
 985                 return ptrace_resume(child, request, SIGKILL);
 986
 987 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 988         case PTRACE_GETREGSET:
 989         case PTRACE_SETREGSET: {
 990                 struct iovec kiov;
 991                 struct iovec __user *uiov = datavp;
 992
 993                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 994                         return -EFAULT;
 995
 996                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 997                     __get_user(kiov.iov_len, &uiov->iov_len))
 998                         return -EFAULT;
 999
1000                 ret = ptrace_regset(child, request, addr, &kiov);
1001                 if (!ret)
1002                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1003                 break;
1004         }
1005 #endif
1006         default:
1007                 break;
1008         }
1009
1010         return ret;
1011 }
1012
1013 static struct task_struct *ptrace_get_task_struct(pid_t pid)
1014 {
1015         struct task_struct *child;
1016
1017         rcu_read_lock();
1018         child = find_task_by_vpid(pid);
1019         if (child)
1020                 get_task_struct(child);
1021         rcu_read_unlock();
1022
1023         if (!child)
1024                 return ERR_PTR(-ESRCH);
1025         return child;
1026 }
1027
1028 #ifndef arch_ptrace_attach
1029 #define arch_ptrace_attach(child)       do { } while (0)
1030 #endif
1031
1032 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
1033                 unsigned long, data)
1034 {
1035         struct task_struct *child;
1036         long ret;
1037
1038         if (request == PTRACE_TRACEME) {
1039                 ret = ptrace_traceme();
1040                 if (!ret)
1041                         arch_ptrace_attach(current);
1042                 goto out;
1043         }
1044
1045         child = ptrace_get_task_struct(pid);
1046         if (IS_ERR(child)) {
1047                 ret = PTR_ERR(child);
1048                 goto out;
1049         }
1050
1051         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1052                 ret = ptrace_attach(child, request, addr, data);
1053                 /*
1054                  * Some architectures need to do book-keeping after
1055                  * a ptrace attach.
1056                  */
1057                 if (!ret)
1058                         arch_ptrace_attach(child);
1059                 goto out_put_task_struct;
1060         }
1061
1062         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1063                                   request == PTRACE_INTERRUPT);
1064         if (ret < 0)
1065                 goto out_put_task_struct;
1066
1067         ret = arch_ptrace(child, request, addr, data);
1068         if (ret || request != PTRACE_DETACH)
1069                 ptrace_unfreeze_traced(child);
1070
1071  out_put_task_struct:
1072         put_task_struct(child);
1073  out:
1074         return ret;
1075 }
1076
1077 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
1078                             unsigned long data)
1079 {
1080         unsigned long tmp;
1081         int copied;
1082
1083         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
1084         if (copied != sizeof(tmp))
1085                 return -EIO;
1086         return put_user(tmp, (unsigned long __user *)data);
1087 }
1088
1089 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
1090                             unsigned long data)
1091 {
1092         int copied;
1093
1094         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
1095         return (copied == sizeof(data)) ? 0 : -EIO;
1096 }
1097
1098 #if defined CONFIG_COMPAT
1099
1100 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
1101                           compat_ulong_t addr, compat_ulong_t data)
1102 {
1103         compat_ulong_t __user *datap = compat_ptr(data);
1104         compat_ulong_t word;
1105         siginfo_t siginfo;
1106         int ret;
1107
1108         switch (request) {
1109         case PTRACE_PEEKTEXT:
1110         case PTRACE_PEEKDATA:
1111                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
1112                 if (ret != sizeof(word))
1113                         ret = -EIO;
1114                 else
1115                         ret = put_user(word, datap);
1116                 break;
1117
1118         case PTRACE_POKETEXT:
1119         case PTRACE_POKEDATA:
1120                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
1121                 ret = (ret != sizeof(data) ? -EIO : 0);
1122                 break;
1123
1124         case PTRACE_GETEVENTMSG:
1125                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
1126                 break;
1127
1128         case PTRACE_GETSIGINFO:
1129                 ret = ptrace_getsiginfo(child, &siginfo);
1130                 if (!ret)
1131                         ret = copy_siginfo_to_user32(
1132                                 (struct compat_siginfo __user *) datap,
1133                                 &siginfo);
1134                 break;
1135
1136         case PTRACE_SETSIGINFO:
1137                 memset(&siginfo, 0, sizeof siginfo);
1138                 if (copy_siginfo_from_user32(
1139                             &siginfo, (struct compat_siginfo __user *) datap))
1140                         ret = -EFAULT;
1141                 else
1142                         ret = ptrace_setsiginfo(child, &siginfo);
1143                 break;
1144 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
1145         case PTRACE_GETREGSET:
1146         case PTRACE_SETREGSET:
1147         {
1148                 struct iovec kiov;
1149                 struct compat_iovec __user *uiov =
1150                         (struct compat_iovec __user *) datap;
1151                 compat_uptr_t ptr;
1152                 compat_size_t len;
1153
1154                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
1155                         return -EFAULT;
1156
1157                 if (__get_user(ptr, &uiov->iov_base) ||
1158                     __get_user(len, &uiov->iov_len))
1159                         return -EFAULT;
1160
1161                 kiov.iov_base = compat_ptr(ptr);
1162                 kiov.iov_len = len;
1163
1164                 ret = ptrace_regset(child, request, addr, &kiov);
1165                 if (!ret)
1166                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
1167                 break;
1168         }
1169 #endif
1170
1171         default:
1172                 ret = ptrace_request(child, request, addr, data);
1173         }
1174
1175         return ret;
1176 }
1177
1178 COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid,
1179                        compat_long_t, addr, compat_long_t, data)
1180 {
1181         struct task_struct *child;
1182         long ret;
1183
1184         if (request == PTRACE_TRACEME) {
1185                 ret = ptrace_traceme();
1186                 goto out;
1187         }
1188
1189         child = ptrace_get_task_struct(pid);
1190         if (IS_ERR(child)) {
1191                 ret = PTR_ERR(child);
1192                 goto out;
1193         }
1194
1195         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1196                 ret = ptrace_attach(child, request, addr, data);
1197                 /*
1198                  * Some architectures need to do book-keeping after
1199                  * a ptrace attach.
1200                  */
1201                 if (!ret)
1202                         arch_ptrace_attach(child);
1203                 goto out_put_task_struct;
1204         }
1205
1206         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1207                                   request == PTRACE_INTERRUPT);
1208         if (!ret) {
1209                 ret = compat_arch_ptrace(child, request, addr, data);
1210                 if (ret || request != PTRACE_DETACH)
1211                         ptrace_unfreeze_traced(child);
1212         }
1213
1214  out_put_task_struct:
1215         put_task_struct(child);
1216  out:
1217         return ret;
1218 }
1219 #endif  /* CONFIG_COMPAT */