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 int __ptrace_may_access(struct task_struct *task, unsigned int mode) 184 { 185 const struct cred *cred = current_cred(), *tcred; 186 187 /* May we inspect the given task? 188 * This check is used both for attaching with ptrace 189 * and for allowing access to sensitive information in /proc. 190 * 191 * ptrace_attach denies several cases that /proc allows 192 * because setting up the necessary parent/child relationship 193 * or halting the specified task is impossible. 194 */ 195 int dumpable = 0; 196 /* Don't let security modules deny introspection */ 197 if (task == current) 198 return 0; 199 rcu_read_lock(); 200 tcred = __task_cred(task); 201 if (cred->user->user_ns == tcred->user->user_ns && 202 (cred->uid == tcred->euid && 203 cred->uid == tcred->suid && 204 cred->uid == tcred->uid && 205 cred->gid == tcred->egid && 206 cred->gid == tcred->sgid && 207 cred->gid == tcred->gid)) 208 goto ok; 209 if (ptrace_has_cap(tcred->user->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 (__ptrace_detach(tracer, p)) 461 list_add(&p->ptrace_entry, &ptrace_dead); 462 } 463 464 write_unlock_irq(&tasklist_lock); 465 BUG_ON(!list_empty(&tracer->ptraced)); 466 467 list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) { 468 list_del_init(&p->ptrace_entry); 469 release_task(p); 470 } 471 472 write_lock_irq(&tasklist_lock); 473 } 474 475 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) 476 { 477 int copied = 0; 478 479 while (len > 0) { 480 char buf[128]; 481 int this_len, retval; 482 483 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 484 retval = access_process_vm(tsk, src, buf, this_len, 0); 485 if (!retval) { 486 if (copied) 487 break; 488 return -EIO; 489 } 490 if (copy_to_user(dst, buf, retval)) 491 return -EFAULT; 492 copied += retval; 493 src += retval; 494 dst += retval; 495 len -= retval; 496 } 497 return copied; 498 } 499 500 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) 501 { 502 int copied = 0; 503 504 while (len > 0) { 505 char buf[128]; 506 int this_len, retval; 507 508 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 509 if (copy_from_user(buf, src, this_len)) 510 return -EFAULT; 511 retval = access_process_vm(tsk, dst, buf, this_len, 1); 512 if (!retval) { 513 if (copied) 514 break; 515 return -EIO; 516 } 517 copied += retval; 518 src += retval; 519 dst += retval; 520 len -= retval; 521 } 522 return copied; 523 } 524 525 static int ptrace_setoptions(struct task_struct *child, unsigned long data) 526 { 527 unsigned flags; 528 529 if (data & ~(unsigned long)PTRACE_O_MASK) 530 return -EINVAL; 531 532 /* Avoid intermediate state when all opts are cleared */ 533 flags = child->ptrace; 534 flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT); 535 flags |= (data << PT_OPT_FLAG_SHIFT); 536 child->ptrace = flags; 537 538 return 0; 539 } 540 541 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info) 542 { 543 unsigned long flags; 544 int error = -ESRCH; 545 546 if (lock_task_sighand(child, &flags)) { 547 error = -EINVAL; 548 if (likely(child->last_siginfo != NULL)) { 549 *info = *child->last_siginfo; 550 error = 0; 551 } 552 unlock_task_sighand(child, &flags); 553 } 554 return error; 555 } 556 557 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info) 558 { 559 unsigned long flags; 560 int error = -ESRCH; 561 562 if (lock_task_sighand(child, &flags)) { 563 error = -EINVAL; 564 if (likely(child->last_siginfo != NULL)) { 565 *child->last_siginfo = *info; 566 error = 0; 567 } 568 unlock_task_sighand(child, &flags); 569 } 570 return error; 571 } 572 573 574 #ifdef PTRACE_SINGLESTEP 575 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP) 576 #else 577 #define is_singlestep(request) 0 578 #endif 579 580 #ifdef PTRACE_SINGLEBLOCK 581 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK) 582 #else 583 #define is_singleblock(request) 0 584 #endif 585 586 #ifdef PTRACE_SYSEMU 587 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP) 588 #else 589 #define is_sysemu_singlestep(request) 0 590 #endif 591 592 static int ptrace_resume(struct task_struct *child, long request, 593 unsigned long data) 594 { 595 if (!valid_signal(data)) 596 return -EIO; 597 598 if (request == PTRACE_SYSCALL) 599 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 600 else 601 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 602 603 #ifdef TIF_SYSCALL_EMU 604 if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP) 605 set_tsk_thread_flag(child, TIF_SYSCALL_EMU); 606 else 607 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); 608 #endif 609 610 if (is_singleblock(request)) { 611 if (unlikely(!arch_has_block_step())) 612 return -EIO; 613 user_enable_block_step(child); 614 } else if (is_singlestep(request) || is_sysemu_singlestep(request)) { 615 if (unlikely(!arch_has_single_step())) 616 return -EIO; 617 user_enable_single_step(child); 618 } else { 619 user_disable_single_step(child); 620 } 621 622 child->exit_code = data; 623 wake_up_state(child, __TASK_TRACED); 624 625 return 0; 626 } 627 628 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 629 630 static const struct user_regset * 631 find_regset(const struct user_regset_view *view, unsigned int type) 632 { 633 const struct user_regset *regset; 634 int n; 635 636 for (n = 0; n < view->n; ++n) { 637 regset = view->regsets + n; 638 if (regset->core_note_type == type) 639 return regset; 640 } 641 642 return NULL; 643 } 644 645 static int ptrace_regset(struct task_struct *task, int req, unsigned int type, 646 struct iovec *kiov) 647 { 648 const struct user_regset_view *view = task_user_regset_view(task); 649 const struct user_regset *regset = find_regset(view, type); 650 int regset_no; 651 652 if (!regset || (kiov->iov_len % regset->size) != 0) 653 return -EINVAL; 654 655 regset_no = regset - view->regsets; 656 kiov->iov_len = min(kiov->iov_len, 657 (__kernel_size_t) (regset->n * regset->size)); 658 659 if (req == PTRACE_GETREGSET) 660 return copy_regset_to_user(task, view, regset_no, 0, 661 kiov->iov_len, kiov->iov_base); 662 else 663 return copy_regset_from_user(task, view, regset_no, 0, 664 kiov->iov_len, kiov->iov_base); 665 } 666 667 #endif 668 669 int ptrace_request(struct task_struct *child, long request, 670 unsigned long addr, unsigned long data) 671 { 672 bool seized = child->ptrace & PT_SEIZED; 673 int ret = -EIO; 674 siginfo_t siginfo, *si; 675 void __user *datavp = (void __user *) data; 676 unsigned long __user *datalp = datavp; 677 unsigned long flags; 678 679 switch (request) { 680 case PTRACE_PEEKTEXT: 681 case PTRACE_PEEKDATA: 682 return generic_ptrace_peekdata(child, addr, data); 683 case PTRACE_POKETEXT: 684 case PTRACE_POKEDATA: 685 return generic_ptrace_pokedata(child, addr, data); 686 687 #ifdef PTRACE_OLDSETOPTIONS 688 case PTRACE_OLDSETOPTIONS: 689 #endif 690 case PTRACE_SETOPTIONS: 691 ret = ptrace_setoptions(child, data); 692 break; 693 case PTRACE_GETEVENTMSG: 694 ret = put_user(child->ptrace_message, datalp); 695 break; 696 697 case PTRACE_GETSIGINFO: 698 ret = ptrace_getsiginfo(child, &siginfo); 699 if (!ret) 700 ret = copy_siginfo_to_user(datavp, &siginfo); 701 break; 702 703 case PTRACE_SETSIGINFO: 704 if (copy_from_user(&siginfo, datavp, sizeof siginfo)) 705 ret = -EFAULT; 706 else 707 ret = ptrace_setsiginfo(child, &siginfo); 708 break; 709 710 case PTRACE_INTERRUPT: 711 /* 712 * Stop tracee without any side-effect on signal or job 713 * control. At least one trap is guaranteed to happen 714 * after this request. If @child is already trapped, the 715 * current trap is not disturbed and another trap will 716 * happen after the current trap is ended with PTRACE_CONT. 717 * 718 * The actual trap might not be PTRACE_EVENT_STOP trap but 719 * the pending condition is cleared regardless. 720 */ 721 if (unlikely(!seized || !lock_task_sighand(child, &flags))) 722 break; 723 724 /* 725 * INTERRUPT doesn't disturb existing trap sans one 726 * exception. If ptracer issued LISTEN for the current 727 * STOP, this INTERRUPT should clear LISTEN and re-trap 728 * tracee into STOP. 729 */ 730 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP))) 731 signal_wake_up(child, child->jobctl & JOBCTL_LISTENING); 732 733 unlock_task_sighand(child, &flags); 734 ret = 0; 735 break; 736 737 case PTRACE_LISTEN: 738 /* 739 * Listen for events. Tracee must be in STOP. It's not 740 * resumed per-se but is not considered to be in TRACED by 741 * wait(2) or ptrace(2). If an async event (e.g. group 742 * stop state change) happens, tracee will enter STOP trap 743 * again. Alternatively, ptracer can issue INTERRUPT to 744 * finish listening and re-trap tracee into STOP. 745 */ 746 if (unlikely(!seized || !lock_task_sighand(child, &flags))) 747 break; 748 749 si = child->last_siginfo; 750 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) { 751 child->jobctl |= JOBCTL_LISTENING; 752 /* 753 * If NOTIFY is set, it means event happened between 754 * start of this trap and now. Trigger re-trap. 755 */ 756 if (child->jobctl & JOBCTL_TRAP_NOTIFY) 757 signal_wake_up(child, true); 758 ret = 0; 759 } 760 unlock_task_sighand(child, &flags); 761 break; 762 763 case PTRACE_DETACH: /* detach a process that was attached. */ 764 ret = ptrace_detach(child, data); 765 break; 766 767 #ifdef CONFIG_BINFMT_ELF_FDPIC 768 case PTRACE_GETFDPIC: { 769 struct mm_struct *mm = get_task_mm(child); 770 unsigned long tmp = 0; 771 772 ret = -ESRCH; 773 if (!mm) 774 break; 775 776 switch (addr) { 777 case PTRACE_GETFDPIC_EXEC: 778 tmp = mm->context.exec_fdpic_loadmap; 779 break; 780 case PTRACE_GETFDPIC_INTERP: 781 tmp = mm->context.interp_fdpic_loadmap; 782 break; 783 default: 784 break; 785 } 786 mmput(mm); 787 788 ret = put_user(tmp, datalp); 789 break; 790 } 791 #endif 792 793 #ifdef PTRACE_SINGLESTEP 794 case PTRACE_SINGLESTEP: 795 #endif 796 #ifdef PTRACE_SINGLEBLOCK 797 case PTRACE_SINGLEBLOCK: 798 #endif 799 #ifdef PTRACE_SYSEMU 800 case PTRACE_SYSEMU: 801 case PTRACE_SYSEMU_SINGLESTEP: 802 #endif 803 case PTRACE_SYSCALL: 804 case PTRACE_CONT: 805 return ptrace_resume(child, request, data); 806 807 case PTRACE_KILL: 808 if (child->exit_state) /* already dead */ 809 return 0; 810 return ptrace_resume(child, request, SIGKILL); 811 812 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 813 case PTRACE_GETREGSET: 814 case PTRACE_SETREGSET: 815 { 816 struct iovec kiov; 817 struct iovec __user *uiov = datavp; 818 819 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) 820 return -EFAULT; 821 822 if (__get_user(kiov.iov_base, &uiov->iov_base) || 823 __get_user(kiov.iov_len, &uiov->iov_len)) 824 return -EFAULT; 825 826 ret = ptrace_regset(child, request, addr, &kiov); 827 if (!ret) 828 ret = __put_user(kiov.iov_len, &uiov->iov_len); 829 break; 830 } 831 #endif 832 default: 833 break; 834 } 835 836 return ret; 837 } 838 839 static struct task_struct *ptrace_get_task_struct(pid_t pid) 840 { 841 struct task_struct *child; 842 843 rcu_read_lock(); 844 child = find_task_by_vpid(pid); 845 if (child) 846 get_task_struct(child); 847 rcu_read_unlock(); 848 849 if (!child) 850 return ERR_PTR(-ESRCH); 851 return child; 852 } 853 854 #ifndef arch_ptrace_attach 855 #define arch_ptrace_attach(child) do { } while (0) 856 #endif 857 858 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, 859 unsigned long, data) 860 { 861 struct task_struct *child; 862 long ret; 863 864 if (request == PTRACE_TRACEME) { 865 ret = ptrace_traceme(); 866 if (!ret) 867 arch_ptrace_attach(current); 868 goto out; 869 } 870 871 child = ptrace_get_task_struct(pid); 872 if (IS_ERR(child)) { 873 ret = PTR_ERR(child); 874 goto out; 875 } 876 877 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { 878 ret = ptrace_attach(child, request, addr, data); 879 /* 880 * Some architectures need to do book-keeping after 881 * a ptrace attach. 882 */ 883 if (!ret) 884 arch_ptrace_attach(child); 885 goto out_put_task_struct; 886 } 887 888 ret = ptrace_check_attach(child, request == PTRACE_KILL || 889 request == PTRACE_INTERRUPT); 890 if (ret < 0) 891 goto out_put_task_struct; 892 893 ret = arch_ptrace(child, request, addr, data); 894 895 out_put_task_struct: 896 put_task_struct(child); 897 out: 898 return ret; 899 } 900 901 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, 902 unsigned long data) 903 { 904 unsigned long tmp; 905 int copied; 906 907 copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); 908 if (copied != sizeof(tmp)) 909 return -EIO; 910 return put_user(tmp, (unsigned long __user *)data); 911 } 912 913 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, 914 unsigned long data) 915 { 916 int copied; 917 918 copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); 919 return (copied == sizeof(data)) ? 0 : -EIO; 920 } 921 922 #if defined CONFIG_COMPAT 923 #include <linux/compat.h> 924 925 int compat_ptrace_request(struct task_struct *child, compat_long_t request, 926 compat_ulong_t addr, compat_ulong_t data) 927 { 928 compat_ulong_t __user *datap = compat_ptr(data); 929 compat_ulong_t word; 930 siginfo_t siginfo; 931 int ret; 932 933 switch (request) { 934 case PTRACE_PEEKTEXT: 935 case PTRACE_PEEKDATA: 936 ret = access_process_vm(child, addr, &word, sizeof(word), 0); 937 if (ret != sizeof(word)) 938 ret = -EIO; 939 else 940 ret = put_user(word, datap); 941 break; 942 943 case PTRACE_POKETEXT: 944 case PTRACE_POKEDATA: 945 ret = access_process_vm(child, addr, &data, sizeof(data), 1); 946 ret = (ret != sizeof(data) ? -EIO : 0); 947 break; 948 949 case PTRACE_GETEVENTMSG: 950 ret = put_user((compat_ulong_t) child->ptrace_message, datap); 951 break; 952 953 case PTRACE_GETSIGINFO: 954 ret = ptrace_getsiginfo(child, &siginfo); 955 if (!ret) 956 ret = copy_siginfo_to_user32( 957 (struct compat_siginfo __user *) datap, 958 &siginfo); 959 break; 960 961 case PTRACE_SETSIGINFO: 962 memset(&siginfo, 0, sizeof siginfo); 963 if (copy_siginfo_from_user32( 964 &siginfo, (struct compat_siginfo __user *) datap)) 965 ret = -EFAULT; 966 else 967 ret = ptrace_setsiginfo(child, &siginfo); 968 break; 969 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 970 case PTRACE_GETREGSET: 971 case PTRACE_SETREGSET: 972 { 973 struct iovec kiov; 974 struct compat_iovec __user *uiov = 975 (struct compat_iovec __user *) datap; 976 compat_uptr_t ptr; 977 compat_size_t len; 978 979 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) 980 return -EFAULT; 981 982 if (__get_user(ptr, &uiov->iov_base) || 983 __get_user(len, &uiov->iov_len)) 984 return -EFAULT; 985 986 kiov.iov_base = compat_ptr(ptr); 987 kiov.iov_len = len; 988 989 ret = ptrace_regset(child, request, addr, &kiov); 990 if (!ret) 991 ret = __put_user(kiov.iov_len, &uiov->iov_len); 992 break; 993 } 994 #endif 995 996 default: 997 ret = ptrace_request(child, request, addr, data); 998 } 999 1000 return ret; 1001 } 1002 1003 asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, 1004 compat_long_t addr, compat_long_t data) 1005 { 1006 struct task_struct *child; 1007 long ret; 1008 1009 if (request == PTRACE_TRACEME) { 1010 ret = ptrace_traceme(); 1011 goto out; 1012 } 1013 1014 child = ptrace_get_task_struct(pid); 1015 if (IS_ERR(child)) { 1016 ret = PTR_ERR(child); 1017 goto out; 1018 } 1019 1020 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { 1021 ret = ptrace_attach(child, request, addr, data); 1022 /* 1023 * Some architectures need to do book-keeping after 1024 * a ptrace attach. 1025 */ 1026 if (!ret) 1027 arch_ptrace_attach(child); 1028 goto out_put_task_struct; 1029 } 1030 1031 ret = ptrace_check_attach(child, request == PTRACE_KILL || 1032 request == PTRACE_INTERRUPT); 1033 if (!ret) 1034 ret = compat_arch_ptrace(child, request, addr, data); 1035 1036 out_put_task_struct: 1037 put_task_struct(child); 1038 out: 1039 return ret; 1040 } 1041 #endif /* CONFIG_COMPAT */ 1042 1043 #ifdef CONFIG_HAVE_HW_BREAKPOINT 1044 int ptrace_get_breakpoints(struct task_struct *tsk) 1045 { 1046 if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt)) 1047 return 0; 1048 1049 return -1; 1050 } 1051 1052 void ptrace_put_breakpoints(struct task_struct *tsk) 1053 { 1054 if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt)) 1055 flush_ptrace_hw_breakpoint(tsk); 1056 } 1057 #endif /* CONFIG_HAVE_HW_BREAKPOINT */ 1058