kernel/ptrace.c

   1 /*
   2  * linux/kernel/ptrace.c
   3  *
   4  * (C) Copyright 1999 Linus Torvalds
   5  *
   6  * Common interfaces for "ptrace()" which we do not want
   7  * to continually duplicate across every architecture.
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/export.h>
  12 #include <linux/sched.h>
  13 #include <linux/errno.h>
  14 #include <linux/mm.h>
  15 #include <linux/highmem.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/security.h>
  19 #include <linux/signal.h>
  20 #include <linux/audit.h>
  21 #include <linux/pid_namespace.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/regset.h>
  25 #include <linux/hw_breakpoint.h>
  26 #include <linux/cn_proc.h>
  27
  28
  29 static int ptrace_trapping_sleep_fn(void *flags)
  30 {
  31         schedule();
  32         return 0;
  33 }
  34
  35 /*
  36  * ptrace a task: make the debugger its new parent and
  37  * move it to the ptrace list.
  38  *
  39  * Must be called with the tasklist lock write-held.
  40  */
  41 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
  42 {
  43         BUG_ON(!list_empty(&child->ptrace_entry));
  44         list_add(&child->ptrace_entry, &new_parent->ptraced);
  45         child->parent = new_parent;
  46 }
  47
  48 /**
  49  * __ptrace_unlink - unlink ptracee and restore its execution state
  50  * @child: ptracee to be unlinked
  51  *
  52  * Remove @child from the ptrace list, move it back to the original parent,
  53  * and restore the execution state so that it conforms to the group stop
  54  * state.
  55  *
  56  * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer
  57  * exiting.  For PTRACE_DETACH, unless the ptracee has been killed between
  58  * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED.
  59  * If the ptracer is exiting, the ptracee can be in any state.
  60  *
  61  * After detach, the ptracee should be in a state which conforms to the
  62  * group stop.  If the group is stopped or in the process of stopping, the
  63  * ptracee should be put into TASK_STOPPED; otherwise, it should be woken
  64  * up from TASK_TRACED.
  65  *
  66  * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED,
  67  * it goes through TRACED -> RUNNING -> STOPPED transition which is similar
  68  * to but in the opposite direction of what happens while attaching to a
  69  * stopped task.  However, in this direction, the intermediate RUNNING
  70  * state is not hidden even from the current ptracer and if it immediately
  71  * re-attaches and performs a WNOHANG wait(2), it may fail.
  72  *
  73  * CONTEXT:
  74  * write_lock_irq(tasklist_lock)
  75  */
  76 void __ptrace_unlink(struct task_struct *child)
  77 {
  78         BUG_ON(!child->ptrace);
  79
  80         child->ptrace = 0;
  81         child->parent = child->real_parent;
  82         list_del_init(&child->ptrace_entry);
  83
  84         spin_lock(&child->sighand->siglock);
  85
  86         /*
  87          * Clear all pending traps and TRAPPING.  TRAPPING should be
  88          * cleared regardless of JOBCTL_STOP_PENDING.  Do it explicitly.
  89          */
  90         task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK);
  91         task_clear_jobctl_trapping(child);
  92
  93         /*
  94          * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and
  95          * @child isn't dead.
  96          */
  97         if (!(child->flags & PF_EXITING) &&
  98             (child->signal->flags & SIGNAL_STOP_STOPPED ||
  99              child->signal->group_stop_count)) {
 100                 child->jobctl |= JOBCTL_STOP_PENDING;
 101
 102                 /*
 103                  * This is only possible if this thread was cloned by the
 104                  * traced task running in the stopped group, set the signal
 105                  * for the future reports.
 106                  * FIXME: we should change ptrace_init_task() to handle this
 107                  * case.
 108                  */
 109                 if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
 110                         child->jobctl |= SIGSTOP;
 111         }
 112
 113         /*
 114          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
 115          * @child in the butt.  Note that @resume should be used iff @child
 116          * is in TASK_TRACED; otherwise, we might unduly disrupt
 117          * TASK_KILLABLE sleeps.
 118          */
 119         if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child))
 120                 signal_wake_up(child, task_is_traced(child));
 121
 122         spin_unlock(&child->sighand->siglock);
 123 }
 124
 125 /**
 126  * ptrace_check_attach - check whether ptracee is ready for ptrace operation
 127  * @child: ptracee to check for
 128  * @ignore_state: don't check whether @child is currently %TASK_TRACED
 129  *
 130  * Check whether @child is being ptraced by %current and ready for further
 131  * ptrace operations.  If @ignore_state is %false, @child also should be in
 132  * %TASK_TRACED state and on return the child is guaranteed to be traced
 133  * and not executing.  If @ignore_state is %true, @child can be in any
 134  * state.
 135  *
 136  * CONTEXT:
 137  * Grabs and releases tasklist_lock and @child->sighand->siglock.
 138  *
 139  * RETURNS:
 140  * 0 on success, -ESRCH if %child is not ready.
 141  */
 142 int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 143 {
 144         int ret = -ESRCH;
 145
 146         /*
 147          * We take the read lock around doing both checks to close a
 148          * possible race where someone else was tracing our child and
 149          * detached between these two checks.  After this locked check,
 150          * we are sure that this is our traced child and that can only
 151          * be changed by us so it's not changing right after this.
 152          */
 153         read_lock(&tasklist_lock);
 154         if ((child->ptrace & PT_PTRACED) && child->parent == current) {
 155                 /*
 156                  * child->sighand can't be NULL, release_task()
 157                  * does ptrace_unlink() before __exit_signal().
 158                  */
 159                 spin_lock_irq(&child->sighand->siglock);
 160                 WARN_ON_ONCE(task_is_stopped(child));
 161                 if (ignore_state || (task_is_traced(child) &&
 162                                      !(child->jobctl & JOBCTL_LISTENING)))
 163                         ret = 0;
 164                 spin_unlock_irq(&child->sighand->siglock);
 165         }
 166         read_unlock(&tasklist_lock);
 167
 168         if (!ret && !ignore_state)
 169                 ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH;
 170
 171         /* All systems go.. */
 172         return ret;
 173 }
 174
 175 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 176 {
 177         if (mode & PTRACE_MODE_NOAUDIT)
 178                 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
 179         else
 180                 return has_ns_capability(current, ns, CAP_SYS_PTRACE);
 181 }
 182
 183 /* Returns 0 on success, -errno on denial. */
 184 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 185 {
 186         const struct cred *cred = current_cred(), *tcred;
 187
 188         /* May we inspect the given task?
 189          * This check is used both for attaching with ptrace
 190          * and for allowing access to sensitive information in /proc.
 191          *
 192          * ptrace_attach denies several cases that /proc allows
 193          * because setting up the necessary parent/child relationship
 194          * or halting the specified task is impossible.
 195          */
 196         int dumpable = 0;
 197         /* Don't let security modules deny introspection */
 198         if (task == current)
 199                 return 0;
 200         rcu_read_lock();
 201         tcred = __task_cred(task);
 202         if (uid_eq(cred->uid, tcred->euid) &&
 203             uid_eq(cred->uid, tcred->suid) &&
 204             uid_eq(cred->uid, tcred->uid)  &&
 205             gid_eq(cred->gid, tcred->egid) &&
 206             gid_eq(cred->gid, tcred->sgid) &&
 207             gid_eq(cred->gid, tcred->gid))
 208                 goto ok;
 209         if (ptrace_has_cap(tcred->user_ns, mode))
 210                 goto ok;
 211         rcu_read_unlock();
 212         return -EPERM;
 213 ok:
 214         rcu_read_unlock();
 215         smp_rmb();
 216         if (task->mm)
 217                 dumpable = get_dumpable(task->mm);
 218         if (!dumpable  && !ptrace_has_cap(task_user_ns(task), mode))
 219                 return -EPERM;
 220
 221         return security_ptrace_access_check(task, mode);
 222 }
 223
 224 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 225 {
 226         int err;
 227         task_lock(task);
 228         err = __ptrace_may_access(task, mode);
 229         task_unlock(task);
 230         return !err;
 231 }
 232
 233 static int ptrace_attach(struct task_struct *task, long request,
 234                          unsigned long addr,
 235                          unsigned long flags)
 236 {
 237         bool seize = (request == PTRACE_SEIZE);
 238         int retval;
 239
 240         retval = -EIO;
 241         if (seize) {
 242                 if (addr != 0)
 243                         goto out;
 244                 if (flags & ~(unsigned long)PTRACE_O_MASK)
 245                         goto out;
 246                 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT);
 247         } else {
 248                 flags = PT_PTRACED;
 249         }
 250
 251         audit_ptrace(task);
 252
 253         retval = -EPERM;
 254         if (unlikely(task->flags & PF_KTHREAD))
 255                 goto out;
 256         if (same_thread_group(task, current))
 257                 goto out;
 258
 259         /*
 260          * Protect exec's credential calculations against our interference;
 261          * SUID, SGID and LSM creds get determined differently
 262          * under ptrace.
 263          */
 264         retval = -ERESTARTNOINTR;
 265         if (mutex_lock_interruptible(&task->signal->cred_guard_mutex))
 266                 goto out;
 267
 268         task_lock(task);
 269         retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH);
 270         task_unlock(task);
 271         if (retval)
 272                 goto unlock_creds;
 273
 274         write_lock_irq(&tasklist_lock);
 275         retval = -EPERM;
 276         if (unlikely(task->exit_state))
 277                 goto unlock_tasklist;
 278         if (task->ptrace)
 279                 goto unlock_tasklist;
 280
 281         if (seize)
 282                 flags |= PT_SEIZED;
 283         if (ns_capable(task_user_ns(task), CAP_SYS_PTRACE))
 284                 flags |= PT_PTRACE_CAP;
 285         task->ptrace = flags;
 286
 287         __ptrace_link(task, current);
 288
 289         /* SEIZE doesn't trap tracee on attach */
 290         if (!seize)
 291                 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 292
 293         spin_lock(&task->sighand->siglock);
 294
 295         /*
 296          * If the task is already STOPPED, set JOBCTL_TRAP_STOP and
 297          * TRAPPING, and kick it so that it transits to TRACED.  TRAPPING
 298          * will be cleared if the child completes the transition or any
 299          * event which clears the group stop states happens.  We'll wait
 300          * for the transition to complete before returning from this
 301          * function.
 302          *
 303          * This hides STOPPED -> RUNNING -> TRACED transition from the
 304          * attaching thread but a different thread in the same group can
 305          * still observe the transient RUNNING state.  IOW, if another
 306          * thread's WNOHANG wait(2) on the stopped tracee races against
 307          * ATTACH, the wait(2) may fail due to the transient RUNNING.
 308          *
 309          * The following task_is_stopped() test is safe as both transitions
 310          * in and out of STOPPED are protected by siglock.
 311          */
 312         if (task_is_stopped(task) &&
 313             task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING))
 314                 signal_wake_up(task, 1);
 315
 316         spin_unlock(&task->sighand->siglock);
 317
 318         retval = 0;
 319 unlock_tasklist:
 320         write_unlock_irq(&tasklist_lock);
 321 unlock_creds:
 322         mutex_unlock(&task->signal->cred_guard_mutex);
 323 out:
 324         if (!retval) {
 325                 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT,
 326                             ptrace_trapping_sleep_fn, TASK_UNINTERRUPTIBLE);
 327                 proc_ptrace_connector(task, PTRACE_ATTACH);
 328         }
 329
 330         return retval;
 331 }
 332
 333 /**
 334  * ptrace_traceme  --  helper for PTRACE_TRACEME
 335  *
 336  * Performs checks and sets PT_PTRACED.
 337  * Should be used by all ptrace implementations for PTRACE_TRACEME.
 338  */
 339 static int ptrace_traceme(void)
 340 {
 341         int ret = -EPERM;
 342
 343         write_lock_irq(&tasklist_lock);
 344         /* Are we already being traced? */
 345         if (!current->ptrace) {
 346                 ret = security_ptrace_traceme(current->parent);
 347                 /*
 348                  * Check PF_EXITING to ensure ->real_parent has not passed
 349                  * exit_ptrace(). Otherwise we don't report the error but
 350                  * pretend ->real_parent untraces us right after return.
 351                  */
 352                 if (!ret && !(current->real_parent->flags & PF_EXITING)) {
 353                         current->ptrace = PT_PTRACED;
 354                         __ptrace_link(current, current->real_parent);
 355                 }
 356         }
 357         write_unlock_irq(&tasklist_lock);
 358
 359         return ret;
 360 }
 361
 362 /*
 363  * Called with irqs disabled, returns true if childs should reap themselves.
 364  */
 365 static int ignoring_children(struct sighand_struct *sigh)
 366 {
 367         int ret;
 368         spin_lock(&sigh->siglock);
 369         ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) ||
 370               (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
 371         spin_unlock(&sigh->siglock);
 372         return ret;
 373 }
 374
 375 /*
 376  * Called with tasklist_lock held for writing.
 377  * Unlink a traced task, and clean it up if it was a traced zombie.
 378  * Return true if it needs to be reaped with release_task().
 379  * (We can't call release_task() here because we already hold tasklist_lock.)
 380  *
 381  * If it's a zombie, our attachedness prevented normal parent notification
 382  * or self-reaping.  Do notification now if it would have happened earlier.
 383  * If it should reap itself, return true.
 384  *
 385  * If it's our own child, there is no notification to do. But if our normal
 386  * children self-reap, then this child was prevented by ptrace and we must
 387  * reap it now, in that case we must also wake up sub-threads sleeping in
 388  * do_wait().
 389  */
 390 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
 391 {
 392         bool dead;
 393
 394         __ptrace_unlink(p);
 395
 396         if (p->exit_state != EXIT_ZOMBIE)
 397                 return false;
 398
 399         dead = !thread_group_leader(p);
 400
 401         if (!dead && thread_group_empty(p)) {
 402                 if (!same_thread_group(p->real_parent, tracer))
 403                         dead = do_notify_parent(p, p->exit_signal);
 404                 else if (ignoring_children(tracer->sighand)) {
 405                         __wake_up_parent(p, tracer);
 406                         dead = true;
 407                 }
 408         }
 409         /* Mark it as in the process of being reaped. */
 410         if (dead)
 411                 p->exit_state = EXIT_DEAD;
 412         return dead;
 413 }
 414
 415 static int ptrace_detach(struct task_struct *child, unsigned int data)
 416 {
 417         bool dead = false;
 418
 419         if (!valid_signal(data))
 420                 return -EIO;
 421
 422         /* Architecture-specific hardware disable .. */
 423         ptrace_disable(child);
 424         clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 425
 426         write_lock_irq(&tasklist_lock);
 427         /*
 428          * This child can be already killed. Make sure de_thread() or
 429          * our sub-thread doing do_wait() didn't do release_task() yet.
 430          */
 431         if (child->ptrace) {
 432                 child->exit_code = data;
 433                 dead = __ptrace_detach(current, child);
 434         }
 435         write_unlock_irq(&tasklist_lock);
 436
 437         proc_ptrace_connector(child, PTRACE_DETACH);
 438         if (unlikely(dead))
 439                 release_task(child);
 440
 441         return 0;
 442 }
 443
 444 /*
 445  * Detach all tasks we were using ptrace on. Called with tasklist held
 446  * for writing, and returns with it held too. But note it can release
 447  * and reacquire the lock.
 448  */
 449 void exit_ptrace(struct task_struct *tracer)
 450         __releases(&tasklist_lock)
 451         __acquires(&tasklist_lock)
 452 {
 453         struct task_struct *p, *n;
 454         LIST_HEAD(ptrace_dead);
 455
 456         if (likely(list_empty(&tracer->ptraced)))
 457                 return;
 458
 459         list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 460                 if (unlikely(p->ptrace & PT_EXITKILL))
 461                         send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
 462
 463                 if (__ptrace_detach(tracer, p))
 464                         list_add(&p->ptrace_entry, &ptrace_dead);
 465         }
 466
 467         write_unlock_irq(&tasklist_lock);
 468         BUG_ON(!list_empty(&tracer->ptraced));
 469
 470         list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) {
 471                 list_del_init(&p->ptrace_entry);
 472                 release_task(p);
 473         }
 474
 475         write_lock_irq(&tasklist_lock);
 476 }
 477
 478 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len)
 479 {
 480         int copied = 0;
 481
 482         while (len > 0) {
 483                 char buf[128];
 484                 int this_len, retval;
 485
 486                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 487                 retval = access_process_vm(tsk, src, buf, this_len, 0);
 488                 if (!retval) {
 489                         if (copied)
 490                                 break;
 491                         return -EIO;
 492                 }
 493                 if (copy_to_user(dst, buf, retval))
 494                         return -EFAULT;
 495                 copied += retval;
 496                 src += retval;
 497                 dst += retval;
 498                 len -= retval;
 499         }
 500         return copied;
 501 }
 502
 503 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len)
 504 {
 505         int copied = 0;
 506
 507         while (len > 0) {
 508                 char buf[128];
 509                 int this_len, retval;
 510
 511                 this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 512                 if (copy_from_user(buf, src, this_len))
 513                         return -EFAULT;
 514                 retval = access_process_vm(tsk, dst, buf, this_len, 1);
 515                 if (!retval) {
 516                         if (copied)
 517                                 break;
 518                         return -EIO;
 519                 }
 520                 copied += retval;
 521                 src += retval;
 522                 dst += retval;
 523                 len -= retval;
 524         }
 525         return copied;
 526 }
 527
 528 static int ptrace_setoptions(struct task_struct *child, unsigned long data)
 529 {
 530         unsigned flags;
 531
 532         if (data & ~(unsigned long)PTRACE_O_MASK)
 533                 return -EINVAL;
 534
 535         /* Avoid intermediate state when all opts are cleared */
 536         flags = child->ptrace;
 537         flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT);
 538         flags |= (data << PT_OPT_FLAG_SHIFT);
 539         child->ptrace = flags;
 540
 541         return 0;
 542 }
 543
 544 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info)
 545 {
 546         unsigned long flags;
 547         int error = -ESRCH;
 548
 549         if (lock_task_sighand(child, &flags)) {
 550                 error = -EINVAL;
 551                 if (likely(child->last_siginfo != NULL)) {
 552                         *info = *child->last_siginfo;
 553                         error = 0;
 554                 }
 555                 unlock_task_sighand(child, &flags);
 556         }
 557         return error;
 558 }
 559
 560 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info)
 561 {
 562         unsigned long flags;
 563         int error = -ESRCH;
 564
 565         if (lock_task_sighand(child, &flags)) {
 566                 error = -EINVAL;
 567                 if (likely(child->last_siginfo != NULL)) {
 568                         *child->last_siginfo = *info;
 569                         error = 0;
 570                 }
 571                 unlock_task_sighand(child, &flags);
 572         }
 573         return error;
 574 }
 575
 576
 577 #ifdef PTRACE_SINGLESTEP
 578 #define is_singlestep(request)          ((request) == PTRACE_SINGLESTEP)
 579 #else
 580 #define is_singlestep(request)          0
 581 #endif
 582
 583 #ifdef PTRACE_SINGLEBLOCK
 584 #define is_singleblock(request)         ((request) == PTRACE_SINGLEBLOCK)
 585 #else
 586 #define is_singleblock(request)         0
 587 #endif
 588
 589 #ifdef PTRACE_SYSEMU
 590 #define is_sysemu_singlestep(request)   ((request) == PTRACE_SYSEMU_SINGLESTEP)
 591 #else
 592 #define is_sysemu_singlestep(request)   0
 593 #endif
 594
 595 static int ptrace_resume(struct task_struct *child, long request,
 596                          unsigned long data)
 597 {
 598         if (!valid_signal(data))
 599                 return -EIO;
 600
 601         if (request == PTRACE_SYSCALL)
 602                 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 603         else
 604                 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
 605
 606 #ifdef TIF_SYSCALL_EMU
 607         if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)
 608                 set_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 609         else
 610                 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
 611 #endif
 612
 613         if (is_singleblock(request)) {
 614                 if (unlikely(!arch_has_block_step()))
 615                         return -EIO;
 616                 user_enable_block_step(child);
 617         } else if (is_singlestep(request) || is_sysemu_singlestep(request)) {
 618                 if (unlikely(!arch_has_single_step()))
 619                         return -EIO;
 620                 user_enable_single_step(child);
 621         } else {
 622                 user_disable_single_step(child);
 623         }
 624
 625         child->exit_code = data;
 626         wake_up_state(child, __TASK_TRACED);
 627
 628         return 0;
 629 }
 630
 631 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 632
 633 static const struct user_regset *
 634 find_regset(const struct user_regset_view *view, unsigned int type)
 635 {
 636         const struct user_regset *regset;
 637         int n;
 638
 639         for (n = 0; n < view->n; ++n) {
 640                 regset = view->regsets + n;
 641                 if (regset->core_note_type == type)
 642                         return regset;
 643         }
 644
 645         return NULL;
 646 }
 647
 648 static int ptrace_regset(struct task_struct *task, int req, unsigned int type,
 649                          struct iovec *kiov)
 650 {
 651         const struct user_regset_view *view = task_user_regset_view(task);
 652         const struct user_regset *regset = find_regset(view, type);
 653         int regset_no;
 654
 655         if (!regset || (kiov->iov_len % regset->size) != 0)
 656                 return -EINVAL;
 657
 658         regset_no = regset - view->regsets;
 659         kiov->iov_len = min(kiov->iov_len,
 660                             (__kernel_size_t) (regset->n * regset->size));
 661
 662         if (req == PTRACE_GETREGSET)
 663                 return copy_regset_to_user(task, view, regset_no, 0,
 664                                            kiov->iov_len, kiov->iov_base);
 665         else
 666                 return copy_regset_from_user(task, view, regset_no, 0,
 667                                              kiov->iov_len, kiov->iov_base);
 668 }
 669
 670 #endif
 671
 672 int ptrace_request(struct task_struct *child, long request,
 673                    unsigned long addr, unsigned long data)
 674 {
 675         bool seized = child->ptrace & PT_SEIZED;
 676         int ret = -EIO;
 677         siginfo_t siginfo, *si;
 678         void __user *datavp = (void __user *) data;
 679         unsigned long __user *datalp = datavp;
 680         unsigned long flags;
 681
 682         switch (request) {
 683         case PTRACE_PEEKTEXT:
 684         case PTRACE_PEEKDATA:
 685                 return generic_ptrace_peekdata(child, addr, data);
 686         case PTRACE_POKETEXT:
 687         case PTRACE_POKEDATA:
 688                 return generic_ptrace_pokedata(child, addr, data);
 689
 690 #ifdef PTRACE_OLDSETOPTIONS
 691         case PTRACE_OLDSETOPTIONS:
 692 #endif
 693         case PTRACE_SETOPTIONS:
 694                 ret = ptrace_setoptions(child, data);
 695                 break;
 696         case PTRACE_GETEVENTMSG:
 697                 ret = put_user(child->ptrace_message, datalp);
 698                 break;
 699
 700         case PTRACE_GETSIGINFO:
 701                 ret = ptrace_getsiginfo(child, &siginfo);
 702                 if (!ret)
 703                         ret = copy_siginfo_to_user(datavp, &siginfo);
 704                 break;
 705
 706         case PTRACE_SETSIGINFO:
 707                 if (copy_from_user(&siginfo, datavp, sizeof siginfo))
 708                         ret = -EFAULT;
 709                 else
 710                         ret = ptrace_setsiginfo(child, &siginfo);
 711                 break;
 712
 713         case PTRACE_INTERRUPT:
 714                 /*
 715                  * Stop tracee without any side-effect on signal or job
 716                  * control.  At least one trap is guaranteed to happen
 717                  * after this request.  If @child is already trapped, the
 718                  * current trap is not disturbed and another trap will
 719                  * happen after the current trap is ended with PTRACE_CONT.
 720                  *
 721                  * The actual trap might not be PTRACE_EVENT_STOP trap but
 722                  * the pending condition is cleared regardless.
 723                  */
 724                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 725                         break;
 726
 727                 /*
 728                  * INTERRUPT doesn't disturb existing trap sans one
 729                  * exception.  If ptracer issued LISTEN for the current
 730                  * STOP, this INTERRUPT should clear LISTEN and re-trap
 731                  * tracee into STOP.
 732                  */
 733                 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP)))
 734                         signal_wake_up(child, child->jobctl & JOBCTL_LISTENING);
 735
 736                 unlock_task_sighand(child, &flags);
 737                 ret = 0;
 738                 break;
 739
 740         case PTRACE_LISTEN:
 741                 /*
 742                  * Listen for events.  Tracee must be in STOP.  It's not
 743                  * resumed per-se but is not considered to be in TRACED by
 744                  * wait(2) or ptrace(2).  If an async event (e.g. group
 745                  * stop state change) happens, tracee will enter STOP trap
 746                  * again.  Alternatively, ptracer can issue INTERRUPT to
 747                  * finish listening and re-trap tracee into STOP.
 748                  */
 749                 if (unlikely(!seized || !lock_task_sighand(child, &flags)))
 750                         break;
 751
 752                 si = child->last_siginfo;
 753                 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) {
 754                         child->jobctl |= JOBCTL_LISTENING;
 755                         /*
 756                          * If NOTIFY is set, it means event happened between
 757                          * start of this trap and now.  Trigger re-trap.
 758                          */
 759                         if (child->jobctl & JOBCTL_TRAP_NOTIFY)
 760                                 signal_wake_up(child, true);
 761                         ret = 0;
 762                 }
 763                 unlock_task_sighand(child, &flags);
 764                 break;
 765
 766         case PTRACE_DETACH:      /* detach a process that was attached. */
 767                 ret = ptrace_detach(child, data);
 768                 break;
 769
 770 #ifdef CONFIG_BINFMT_ELF_FDPIC
 771         case PTRACE_GETFDPIC: {
 772                 struct mm_struct *mm = get_task_mm(child);
 773                 unsigned long tmp = 0;
 774
 775                 ret = -ESRCH;
 776                 if (!mm)
 777                         break;
 778
 779                 switch (addr) {
 780                 case PTRACE_GETFDPIC_EXEC:
 781                         tmp = mm->context.exec_fdpic_loadmap;
 782                         break;
 783                 case PTRACE_GETFDPIC_INTERP:
 784                         tmp = mm->context.interp_fdpic_loadmap;
 785                         break;
 786                 default:
 787                         break;
 788                 }
 789                 mmput(mm);
 790
 791                 ret = put_user(tmp, datalp);
 792                 break;
 793         }
 794 #endif
 795
 796 #ifdef PTRACE_SINGLESTEP
 797         case PTRACE_SINGLESTEP:
 798 #endif
 799 #ifdef PTRACE_SINGLEBLOCK
 800         case PTRACE_SINGLEBLOCK:
 801 #endif
 802 #ifdef PTRACE_SYSEMU
 803         case PTRACE_SYSEMU:
 804         case PTRACE_SYSEMU_SINGLESTEP:
 805 #endif
 806         case PTRACE_SYSCALL:
 807         case PTRACE_CONT:
 808                 return ptrace_resume(child, request, data);
 809
 810         case PTRACE_KILL:
 811                 if (child->exit_state)  /* already dead */
 812                         return 0;
 813                 return ptrace_resume(child, request, SIGKILL);
 814
 815 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 816         case PTRACE_GETREGSET:
 817         case PTRACE_SETREGSET:
 818         {
 819                 struct iovec kiov;
 820                 struct iovec __user *uiov = datavp;
 821
 822                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 823                         return -EFAULT;
 824
 825                 if (__get_user(kiov.iov_base, &uiov->iov_base) ||
 826                     __get_user(kiov.iov_len, &uiov->iov_len))
 827                         return -EFAULT;
 828
 829                 ret = ptrace_regset(child, request, addr, &kiov);
 830                 if (!ret)
 831                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 832                 break;
 833         }
 834 #endif
 835         default:
 836                 break;
 837         }
 838
 839         return ret;
 840 }
 841
 842 static struct task_struct *ptrace_get_task_struct(pid_t pid)
 843 {
 844         struct task_struct *child;
 845
 846         rcu_read_lock();
 847         child = find_task_by_vpid(pid);
 848         if (child)
 849                 get_task_struct(child);
 850         rcu_read_unlock();
 851
 852         if (!child)
 853                 return ERR_PTR(-ESRCH);
 854         return child;
 855 }
 856
 857 #ifndef arch_ptrace_attach
 858 #define arch_ptrace_attach(child)       do { } while (0)
 859 #endif
 860
 861 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 862                 unsigned long, data)
 863 {
 864         struct task_struct *child;
 865         long ret;
 866
 867         if (request == PTRACE_TRACEME) {
 868                 ret = ptrace_traceme();
 869                 if (!ret)
 870                         arch_ptrace_attach(current);
 871                 goto out;
 872         }
 873
 874         child = ptrace_get_task_struct(pid);
 875         if (IS_ERR(child)) {
 876                 ret = PTR_ERR(child);
 877                 goto out;
 878         }
 879
 880         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
 881                 ret = ptrace_attach(child, request, addr, data);
 882                 /*
 883                  * Some architectures need to do book-keeping after
 884                  * a ptrace attach.
 885                  */
 886                 if (!ret)
 887                         arch_ptrace_attach(child);
 888                 goto out_put_task_struct;
 889         }
 890
 891         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
 892                                   request == PTRACE_INTERRUPT);
 893         if (ret < 0)
 894                 goto out_put_task_struct;
 895
 896         ret = arch_ptrace(child, request, addr, data);
 897
 898  out_put_task_struct:
 899         put_task_struct(child);
 900  out:
 901         return ret;
 902 }
 903
 904 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 905                             unsigned long data)
 906 {
 907         unsigned long tmp;
 908         int copied;
 909
 910         copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
 911         if (copied != sizeof(tmp))
 912                 return -EIO;
 913         return put_user(tmp, (unsigned long __user *)data);
 914 }
 915
 916 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 917                             unsigned long data)
 918 {
 919         int copied;
 920
 921         copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
 922         return (copied == sizeof(data)) ? 0 : -EIO;
 923 }
 924
 925 #if defined CONFIG_COMPAT
 926 #include <linux/compat.h>
 927
 928 int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 929                           compat_ulong_t addr, compat_ulong_t data)
 930 {
 931         compat_ulong_t __user *datap = compat_ptr(data);
 932         compat_ulong_t word;
 933         siginfo_t siginfo;
 934         int ret;
 935
 936         switch (request) {
 937         case PTRACE_PEEKTEXT:
 938         case PTRACE_PEEKDATA:
 939                 ret = access_process_vm(child, addr, &word, sizeof(word), 0);
 940                 if (ret != sizeof(word))
 941                         ret = -EIO;
 942                 else
 943                         ret = put_user(word, datap);
 944                 break;
 945
 946         case PTRACE_POKETEXT:
 947         case PTRACE_POKEDATA:
 948                 ret = access_process_vm(child, addr, &data, sizeof(data), 1);
 949                 ret = (ret != sizeof(data) ? -EIO : 0);
 950                 break;
 951
 952         case PTRACE_GETEVENTMSG:
 953                 ret = put_user((compat_ulong_t) child->ptrace_message, datap);
 954                 break;
 955
 956         case PTRACE_GETSIGINFO:
 957                 ret = ptrace_getsiginfo(child, &siginfo);
 958                 if (!ret)
 959                         ret = copy_siginfo_to_user32(
 960                                 (struct compat_siginfo __user *) datap,
 961                                 &siginfo);
 962                 break;
 963
 964         case PTRACE_SETSIGINFO:
 965                 memset(&siginfo, 0, sizeof siginfo);
 966                 if (copy_siginfo_from_user32(
 967                             &siginfo, (struct compat_siginfo __user *) datap))
 968                         ret = -EFAULT;
 969                 else
 970                         ret = ptrace_setsiginfo(child, &siginfo);
 971                 break;
 972 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 973         case PTRACE_GETREGSET:
 974         case PTRACE_SETREGSET:
 975         {
 976                 struct iovec kiov;
 977                 struct compat_iovec __user *uiov =
 978                         (struct compat_iovec __user *) datap;
 979                 compat_uptr_t ptr;
 980                 compat_size_t len;
 981
 982                 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov)))
 983                         return -EFAULT;
 984
 985                 if (__get_user(ptr, &uiov->iov_base) ||
 986                     __get_user(len, &uiov->iov_len))
 987                         return -EFAULT;
 988
 989                 kiov.iov_base = compat_ptr(ptr);
 990                 kiov.iov_len = len;
 991
 992                 ret = ptrace_regset(child, request, addr, &kiov);
 993                 if (!ret)
 994                         ret = __put_user(kiov.iov_len, &uiov->iov_len);
 995                 break;
 996         }
 997 #endif
 998
 999         default:
1000                 ret = ptrace_request(child, request, addr, data);
1001         }
1002
1003         return ret;
1004 }
1005
1006 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
1007                                   compat_long_t addr, compat_long_t data)
1008 {
1009         struct task_struct *child;
1010         long ret;
1011
1012         if (request == PTRACE_TRACEME) {
1013                 ret = ptrace_traceme();
1014                 goto out;
1015         }
1016
1017         child = ptrace_get_task_struct(pid);
1018         if (IS_ERR(child)) {
1019                 ret = PTR_ERR(child);
1020                 goto out;
1021         }
1022
1023         if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
1024                 ret = ptrace_attach(child, request, addr, data);
1025                 /*
1026                  * Some architectures need to do book-keeping after
1027                  * a ptrace attach.
1028                  */
1029                 if (!ret)
1030                         arch_ptrace_attach(child);
1031                 goto out_put_task_struct;
1032         }
1033
1034         ret = ptrace_check_attach(child, request == PTRACE_KILL ||
1035                                   request == PTRACE_INTERRUPT);
1036         if (!ret)
1037                 ret = compat_arch_ptrace(child, request, addr, data);
1038
1039  out_put_task_struct:
1040         put_task_struct(child);
1041  out:
1042         return ret;
1043 }
1044 #endif  /* CONFIG_COMPAT */
1045
1046 #ifdef CONFIG_HAVE_HW_BREAKPOINT
1047 int ptrace_get_breakpoints(struct task_struct *tsk)
1048 {
1049         if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt))
1050                 return 0;
1051
1052         return -1;
1053 }
1054
1055 void ptrace_put_breakpoints(struct task_struct *tsk)
1056 {
1057         if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt))
1058                 flush_ptrace_hw_breakpoint(tsk);
1059 }
1060 #endif /* CONFIG_HAVE_HW_BREAKPOINT */