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