1 /* 2 * linux/kernel/ptrace.c 3 * 4 * (C) Copyright 1999 Linus Torvalds 5 * 6 * Common interfaces for "ptrace()" which we do not want 7 * to continually duplicate across every architecture. 8 */ 9 10 #include <linux/capability.h> 11 #include <linux/export.h> 12 #include <linux/sched.h> 13 #include <linux/errno.h> 14 #include <linux/mm.h> 15 #include <linux/highmem.h> 16 #include <linux/pagemap.h> 17 #include <linux/ptrace.h> 18 #include <linux/security.h> 19 #include <linux/signal.h> 20 #include <linux/uio.h> 21 #include <linux/audit.h> 22 #include <linux/pid_namespace.h> 23 #include <linux/syscalls.h> 24 #include <linux/uaccess.h> 25 #include <linux/regset.h> 26 #include <linux/hw_breakpoint.h> 27 #include <linux/cn_proc.h> 28 #include <linux/compat.h> 29 30 31 /* 32 * ptrace a task: make the debugger its new parent and 33 * move it to the ptrace list. 34 * 35 * Must be called with the tasklist lock write-held. 36 */ 37 void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) 38 { 39 BUG_ON(!list_empty(&child->ptrace_entry)); 40 list_add(&child->ptrace_entry, &new_parent->ptraced); 41 child->parent = new_parent; 42 } 43 44 /** 45 * __ptrace_unlink - unlink ptracee and restore its execution state 46 * @child: ptracee to be unlinked 47 * 48 * Remove @child from the ptrace list, move it back to the original parent, 49 * and restore the execution state so that it conforms to the group stop 50 * state. 51 * 52 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer 53 * exiting. For PTRACE_DETACH, unless the ptracee has been killed between 54 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED. 55 * If the ptracer is exiting, the ptracee can be in any state. 56 * 57 * After detach, the ptracee should be in a state which conforms to the 58 * group stop. If the group is stopped or in the process of stopping, the 59 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken 60 * up from TASK_TRACED. 61 * 62 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED, 63 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar 64 * to but in the opposite direction of what happens while attaching to a 65 * stopped task. However, in this direction, the intermediate RUNNING 66 * state is not hidden even from the current ptracer and if it immediately 67 * re-attaches and performs a WNOHANG wait(2), it may fail. 68 * 69 * CONTEXT: 70 * write_lock_irq(tasklist_lock) 71 */ 72 void __ptrace_unlink(struct task_struct *child) 73 { 74 BUG_ON(!child->ptrace); 75 76 child->ptrace = 0; 77 child->parent = child->real_parent; 78 list_del_init(&child->ptrace_entry); 79 80 spin_lock(&child->sighand->siglock); 81 82 /* 83 * Clear all pending traps and TRAPPING. TRAPPING should be 84 * cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly. 85 */ 86 task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK); 87 task_clear_jobctl_trapping(child); 88 89 /* 90 * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and 91 * @child isn't dead. 92 */ 93 if (!(child->flags & PF_EXITING) && 94 (child->signal->flags & SIGNAL_STOP_STOPPED || 95 child->signal->group_stop_count)) { 96 child->jobctl |= JOBCTL_STOP_PENDING; 97 98 /* 99 * This is only possible if this thread was cloned by the 100 * traced task running in the stopped group, set the signal 101 * for the future reports. 102 * FIXME: we should change ptrace_init_task() to handle this 103 * case. 104 */ 105 if (!(child->jobctl & JOBCTL_STOP_SIGMASK)) 106 child->jobctl |= SIGSTOP; 107 } 108 109 /* 110 * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick 111 * @child in the butt. Note that @resume should be used iff @child 112 * is in TASK_TRACED; otherwise, we might unduly disrupt 113 * TASK_KILLABLE sleeps. 114 */ 115 if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child)) 116 ptrace_signal_wake_up(child, true); 117 118 spin_unlock(&child->sighand->siglock); 119 } 120 121 /* Ensure that nothing can wake it up, even SIGKILL */ 122 static bool ptrace_freeze_traced(struct task_struct *task) 123 { 124 bool ret = false; 125 126 /* Lockless, nobody but us can set this flag */ 127 if (task->jobctl & JOBCTL_LISTENING) 128 return ret; 129 130 spin_lock_irq(&task->sighand->siglock); 131 if (task_is_traced(task) && !__fatal_signal_pending(task)) { 132 task->state = __TASK_TRACED; 133 ret = true; 134 } 135 spin_unlock_irq(&task->sighand->siglock); 136 137 return ret; 138 } 139 140 static void ptrace_unfreeze_traced(struct task_struct *task) 141 { 142 if (task->state != __TASK_TRACED) 143 return; 144 145 WARN_ON(!task->ptrace || task->parent != current); 146 147 spin_lock_irq(&task->sighand->siglock); 148 if (__fatal_signal_pending(task)) 149 wake_up_state(task, __TASK_TRACED); 150 else 151 task->state = TASK_TRACED; 152 spin_unlock_irq(&task->sighand->siglock); 153 } 154 155 /** 156 * ptrace_check_attach - check whether ptracee is ready for ptrace operation 157 * @child: ptracee to check for 158 * @ignore_state: don't check whether @child is currently %TASK_TRACED 159 * 160 * Check whether @child is being ptraced by %current and ready for further 161 * ptrace operations. If @ignore_state is %false, @child also should be in 162 * %TASK_TRACED state and on return the child is guaranteed to be traced 163 * and not executing. If @ignore_state is %true, @child can be in any 164 * state. 165 * 166 * CONTEXT: 167 * Grabs and releases tasklist_lock and @child->sighand->siglock. 168 * 169 * RETURNS: 170 * 0 on success, -ESRCH if %child is not ready. 171 */ 172 static int ptrace_check_attach(struct task_struct *child, bool ignore_state) 173 { 174 int ret = -ESRCH; 175 176 /* 177 * We take the read lock around doing both checks to close a 178 * possible race where someone else was tracing our child and 179 * detached between these two checks. After this locked check, 180 * we are sure that this is our traced child and that can only 181 * be changed by us so it's not changing right after this. 182 */ 183 read_lock(&tasklist_lock); 184 if (child->ptrace && child->parent == current) { 185 WARN_ON(child->state == __TASK_TRACED); 186 /* 187 * child->sighand can't be NULL, release_task() 188 * does ptrace_unlink() before __exit_signal(). 189 */ 190 if (ignore_state || ptrace_freeze_traced(child)) 191 ret = 0; 192 } 193 read_unlock(&tasklist_lock); 194 195 if (!ret && !ignore_state) { 196 if (!wait_task_inactive(child, __TASK_TRACED)) { 197 /* 198 * This can only happen if may_ptrace_stop() fails and 199 * ptrace_stop() changes ->state back to TASK_RUNNING, 200 * so we should not worry about leaking __TASK_TRACED. 201 */ 202 WARN_ON(child->state == __TASK_TRACED); 203 ret = -ESRCH; 204 } 205 } 206 207 return ret; 208 } 209 210 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode) 211 { 212 if (mode & PTRACE_MODE_NOAUDIT) 213 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE); 214 else 215 return has_ns_capability(current, ns, CAP_SYS_PTRACE); 216 } 217 218 /* Returns 0 on success, -errno on denial. */ 219 static int __ptrace_may_access(struct task_struct *task, unsigned int mode) 220 { 221 const struct cred *cred = current_cred(), *tcred; 222 223 /* May we inspect the given task? 224 * This check is used both for attaching with ptrace 225 * and for allowing access to sensitive information in /proc. 226 * 227 * ptrace_attach denies several cases that /proc allows 228 * because setting up the necessary parent/child relationship 229 * or halting the specified task is impossible. 230 */ 231 int dumpable = 0; 232 /* Don't let security modules deny introspection */ 233 if (same_thread_group(task, current)) 234 return 0; 235 rcu_read_lock(); 236 tcred = __task_cred(task); 237 if (uid_eq(cred->uid, tcred->euid) && 238 uid_eq(cred->uid, tcred->suid) && 239 uid_eq(cred->uid, tcred->uid) && 240 gid_eq(cred->gid, tcred->egid) && 241 gid_eq(cred->gid, tcred->sgid) && 242 gid_eq(cred->gid, tcred->gid)) 243 goto ok; 244 if (ptrace_has_cap(tcred->user_ns, mode)) 245 goto ok; 246 rcu_read_unlock(); 247 return -EPERM; 248 ok: 249 rcu_read_unlock(); 250 smp_rmb(); 251 if (task->mm) 252 dumpable = get_dumpable(task->mm); 253 rcu_read_lock(); 254 if (dumpable != SUID_DUMP_USER && 255 !ptrace_has_cap(__task_cred(task)->user_ns, mode)) { 256 rcu_read_unlock(); 257 return -EPERM; 258 } 259 rcu_read_unlock(); 260 261 return security_ptrace_access_check(task, mode); 262 } 263 264 bool ptrace_may_access(struct task_struct *task, unsigned int mode) 265 { 266 int err; 267 task_lock(task); 268 err = __ptrace_may_access(task, mode); 269 task_unlock(task); 270 return !err; 271 } 272 273 static int ptrace_attach(struct task_struct *task, long request, 274 unsigned long addr, 275 unsigned long flags) 276 { 277 bool seize = (request == PTRACE_SEIZE); 278 int retval; 279 280 retval = -EIO; 281 if (seize) { 282 if (addr != 0) 283 goto out; 284 if (flags & ~(unsigned long)PTRACE_O_MASK) 285 goto out; 286 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT); 287 } else { 288 flags = PT_PTRACED; 289 } 290 291 audit_ptrace(task); 292 293 retval = -EPERM; 294 if (unlikely(task->flags & PF_KTHREAD)) 295 goto out; 296 if (same_thread_group(task, current)) 297 goto out; 298 299 /* 300 * Protect exec's credential calculations against our interference; 301 * SUID, SGID and LSM creds get determined differently 302 * under ptrace. 303 */ 304 retval = -ERESTARTNOINTR; 305 if (mutex_lock_interruptible(&task->signal->cred_guard_mutex)) 306 goto out; 307 308 task_lock(task); 309 retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH); 310 task_unlock(task); 311 if (retval) 312 goto unlock_creds; 313 314 write_lock_irq(&tasklist_lock); 315 retval = -EPERM; 316 if (unlikely(task->exit_state)) 317 goto unlock_tasklist; 318 if (task->ptrace) 319 goto unlock_tasklist; 320 321 if (seize) 322 flags |= PT_SEIZED; 323 rcu_read_lock(); 324 if (ns_capable(__task_cred(task)->user_ns, CAP_SYS_PTRACE)) 325 flags |= PT_PTRACE_CAP; 326 rcu_read_unlock(); 327 task->ptrace = flags; 328 329 __ptrace_link(task, current); 330 331 /* SEIZE doesn't trap tracee on attach */ 332 if (!seize) 333 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task); 334 335 spin_lock(&task->sighand->siglock); 336 337 /* 338 * If the task is already STOPPED, set JOBCTL_TRAP_STOP and 339 * TRAPPING, and kick it so that it transits to TRACED. TRAPPING 340 * will be cleared if the child completes the transition or any 341 * event which clears the group stop states happens. We'll wait 342 * for the transition to complete before returning from this 343 * function. 344 * 345 * This hides STOPPED -> RUNNING -> TRACED transition from the 346 * attaching thread but a different thread in the same group can 347 * still observe the transient RUNNING state. IOW, if another 348 * thread's WNOHANG wait(2) on the stopped tracee races against 349 * ATTACH, the wait(2) may fail due to the transient RUNNING. 350 * 351 * The following task_is_stopped() test is safe as both transitions 352 * in and out of STOPPED are protected by siglock. 353 */ 354 if (task_is_stopped(task) && 355 task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) 356 signal_wake_up_state(task, __TASK_STOPPED); 357 358 spin_unlock(&task->sighand->siglock); 359 360 retval = 0; 361 unlock_tasklist: 362 write_unlock_irq(&tasklist_lock); 363 unlock_creds: 364 mutex_unlock(&task->signal->cred_guard_mutex); 365 out: 366 if (!retval) { 367 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, 368 TASK_UNINTERRUPTIBLE); 369 proc_ptrace_connector(task, PTRACE_ATTACH); 370 } 371 372 return retval; 373 } 374 375 /** 376 * ptrace_traceme -- helper for PTRACE_TRACEME 377 * 378 * Performs checks and sets PT_PTRACED. 379 * Should be used by all ptrace implementations for PTRACE_TRACEME. 380 */ 381 static int ptrace_traceme(void) 382 { 383 int ret = -EPERM; 384 385 write_lock_irq(&tasklist_lock); 386 /* Are we already being traced? */ 387 if (!current->ptrace) { 388 ret = security_ptrace_traceme(current->parent); 389 /* 390 * Check PF_EXITING to ensure ->real_parent has not passed 391 * exit_ptrace(). Otherwise we don't report the error but 392 * pretend ->real_parent untraces us right after return. 393 */ 394 if (!ret && !(current->real_parent->flags & PF_EXITING)) { 395 current->ptrace = PT_PTRACED; 396 __ptrace_link(current, current->real_parent); 397 } 398 } 399 write_unlock_irq(&tasklist_lock); 400 401 return ret; 402 } 403 404 /* 405 * Called with irqs disabled, returns true if childs should reap themselves. 406 */ 407 static int ignoring_children(struct sighand_struct *sigh) 408 { 409 int ret; 410 spin_lock(&sigh->siglock); 411 ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) || 412 (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT); 413 spin_unlock(&sigh->siglock); 414 return ret; 415 } 416 417 /* 418 * Called with tasklist_lock held for writing. 419 * Unlink a traced task, and clean it up if it was a traced zombie. 420 * Return true if it needs to be reaped with release_task(). 421 * (We can't call release_task() here because we already hold tasklist_lock.) 422 * 423 * If it's a zombie, our attachedness prevented normal parent notification 424 * or self-reaping. Do notification now if it would have happened earlier. 425 * If it should reap itself, return true. 426 * 427 * If it's our own child, there is no notification to do. But if our normal 428 * children self-reap, then this child was prevented by ptrace and we must 429 * reap it now, in that case we must also wake up sub-threads sleeping in 430 * do_wait(). 431 */ 432 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) 433 { 434 bool dead; 435 436 __ptrace_unlink(p); 437 438 if (p->exit_state != EXIT_ZOMBIE) 439 return false; 440 441 dead = !thread_group_leader(p); 442 443 if (!dead && thread_group_empty(p)) { 444 if (!same_thread_group(p->real_parent, tracer)) 445 dead = do_notify_parent(p, p->exit_signal); 446 else if (ignoring_children(tracer->sighand)) { 447 __wake_up_parent(p, tracer); 448 dead = true; 449 } 450 } 451 /* Mark it as in the process of being reaped. */ 452 if (dead) 453 p->exit_state = EXIT_DEAD; 454 return dead; 455 } 456 457 static int ptrace_detach(struct task_struct *child, unsigned int data) 458 { 459 if (!valid_signal(data)) 460 return -EIO; 461 462 /* Architecture-specific hardware disable .. */ 463 ptrace_disable(child); 464 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 465 466 write_lock_irq(&tasklist_lock); 467 /* 468 * We rely on ptrace_freeze_traced(). It can't be killed and 469 * untraced by another thread, it can't be a zombie. 470 */ 471 WARN_ON(!child->ptrace || child->exit_state); 472 /* 473 * tasklist_lock avoids the race with wait_task_stopped(), see 474 * the comment in ptrace_resume(). 475 */ 476 child->exit_code = data; 477 __ptrace_detach(current, child); 478 write_unlock_irq(&tasklist_lock); 479 480 proc_ptrace_connector(child, PTRACE_DETACH); 481 482 return 0; 483 } 484 485 /* 486 * Detach all tasks we were using ptrace on. Called with tasklist held 487 * for writing. 488 */ 489 void exit_ptrace(struct task_struct *tracer, struct list_head *dead) 490 { 491 struct task_struct *p, *n; 492 493 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) { 494 if (unlikely(p->ptrace & PT_EXITKILL)) 495 send_sig_info(SIGKILL, SEND_SIG_FORCED, p); 496 497 if (__ptrace_detach(tracer, p)) 498 list_add(&p->ptrace_entry, dead); 499 } 500 } 501 502 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) 503 { 504 int copied = 0; 505 506 while (len > 0) { 507 char buf[128]; 508 int this_len, retval; 509 510 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 511 retval = access_process_vm(tsk, src, buf, this_len, 0); 512 if (!retval) { 513 if (copied) 514 break; 515 return -EIO; 516 } 517 if (copy_to_user(dst, buf, retval)) 518 return -EFAULT; 519 copied += retval; 520 src += retval; 521 dst += retval; 522 len -= retval; 523 } 524 return copied; 525 } 526 527 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) 528 { 529 int copied = 0; 530 531 while (len > 0) { 532 char buf[128]; 533 int this_len, retval; 534 535 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 536 if (copy_from_user(buf, src, this_len)) 537 return -EFAULT; 538 retval = access_process_vm(tsk, dst, buf, this_len, 1); 539 if (!retval) { 540 if (copied) 541 break; 542 return -EIO; 543 } 544 copied += retval; 545 src += retval; 546 dst += retval; 547 len -= retval; 548 } 549 return copied; 550 } 551 552 static int ptrace_setoptions(struct task_struct *child, unsigned long data) 553 { 554 unsigned flags; 555 556 if (data & ~(unsigned long)PTRACE_O_MASK) 557 return -EINVAL; 558 559 if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) { 560 if (!config_enabled(CONFIG_CHECKPOINT_RESTORE) || 561 !config_enabled(CONFIG_SECCOMP)) 562 return -EINVAL; 563 564 if (!capable(CAP_SYS_ADMIN)) 565 return -EPERM; 566 567 if (seccomp_mode(¤t->seccomp) != SECCOMP_MODE_DISABLED || 568 current->ptrace & PT_SUSPEND_SECCOMP) 569 return -EPERM; 570 } 571 572 /* Avoid intermediate state when all opts are cleared */ 573 flags = child->ptrace; 574 flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT); 575 flags |= (data << PT_OPT_FLAG_SHIFT); 576 child->ptrace = flags; 577 578 return 0; 579 } 580 581 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info) 582 { 583 unsigned long flags; 584 int error = -ESRCH; 585 586 if (lock_task_sighand(child, &flags)) { 587 error = -EINVAL; 588 if (likely(child->last_siginfo != NULL)) { 589 *info = *child->last_siginfo; 590 error = 0; 591 } 592 unlock_task_sighand(child, &flags); 593 } 594 return error; 595 } 596 597 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info) 598 { 599 unsigned long flags; 600 int error = -ESRCH; 601 602 if (lock_task_sighand(child, &flags)) { 603 error = -EINVAL; 604 if (likely(child->last_siginfo != NULL)) { 605 *child->last_siginfo = *info; 606 error = 0; 607 } 608 unlock_task_sighand(child, &flags); 609 } 610 return error; 611 } 612 613 static int ptrace_peek_siginfo(struct task_struct *child, 614 unsigned long addr, 615 unsigned long data) 616 { 617 struct ptrace_peeksiginfo_args arg; 618 struct sigpending *pending; 619 struct sigqueue *q; 620 int ret, i; 621 622 ret = copy_from_user(&arg, (void __user *) addr, 623 sizeof(struct ptrace_peeksiginfo_args)); 624 if (ret) 625 return -EFAULT; 626 627 if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED) 628 return -EINVAL; /* unknown flags */ 629 630 if (arg.nr < 0) 631 return -EINVAL; 632 633 if (arg.flags & PTRACE_PEEKSIGINFO_SHARED) 634 pending = &child->signal->shared_pending; 635 else 636 pending = &child->pending; 637 638 for (i = 0; i < arg.nr; ) { 639 siginfo_t info; 640 s32 off = arg.off + i; 641 642 spin_lock_irq(&child->sighand->siglock); 643 list_for_each_entry(q, &pending->list, list) { 644 if (!off--) { 645 copy_siginfo(&info, &q->info); 646 break; 647 } 648 } 649 spin_unlock_irq(&child->sighand->siglock); 650 651 if (off >= 0) /* beyond the end of the list */ 652 break; 653 654 #ifdef CONFIG_COMPAT 655 if (unlikely(is_compat_task())) { 656 compat_siginfo_t __user *uinfo = compat_ptr(data); 657 658 if (copy_siginfo_to_user32(uinfo, &info) || 659 __put_user(info.si_code, &uinfo->si_code)) { 660 ret = -EFAULT; 661 break; 662 } 663 664 } else 665 #endif 666 { 667 siginfo_t __user *uinfo = (siginfo_t __user *) data; 668 669 if (copy_siginfo_to_user(uinfo, &info) || 670 __put_user(info.si_code, &uinfo->si_code)) { 671 ret = -EFAULT; 672 break; 673 } 674 } 675 676 data += sizeof(siginfo_t); 677 i++; 678 679 if (signal_pending(current)) 680 break; 681 682 cond_resched(); 683 } 684 685 if (i > 0) 686 return i; 687 688 return ret; 689 } 690 691 #ifdef PTRACE_SINGLESTEP 692 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP) 693 #else 694 #define is_singlestep(request) 0 695 #endif 696 697 #ifdef PTRACE_SINGLEBLOCK 698 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK) 699 #else 700 #define is_singleblock(request) 0 701 #endif 702 703 #ifdef PTRACE_SYSEMU 704 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP) 705 #else 706 #define is_sysemu_singlestep(request) 0 707 #endif 708 709 static int ptrace_resume(struct task_struct *child, long request, 710 unsigned long data) 711 { 712 bool need_siglock; 713 714 if (!valid_signal(data)) 715 return -EIO; 716 717 if (request == PTRACE_SYSCALL) 718 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 719 else 720 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 721 722 #ifdef TIF_SYSCALL_EMU 723 if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP) 724 set_tsk_thread_flag(child, TIF_SYSCALL_EMU); 725 else 726 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); 727 #endif 728 729 if (is_singleblock(request)) { 730 if (unlikely(!arch_has_block_step())) 731 return -EIO; 732 user_enable_block_step(child); 733 } else if (is_singlestep(request) || is_sysemu_singlestep(request)) { 734 if (unlikely(!arch_has_single_step())) 735 return -EIO; 736 user_enable_single_step(child); 737 } else { 738 user_disable_single_step(child); 739 } 740 741 /* 742 * Change ->exit_code and ->state under siglock to avoid the race 743 * with wait_task_stopped() in between; a non-zero ->exit_code will 744 * wrongly look like another report from tracee. 745 * 746 * Note that we need siglock even if ->exit_code == data and/or this 747 * status was not reported yet, the new status must not be cleared by 748 * wait_task_stopped() after resume. 749 * 750 * If data == 0 we do not care if wait_task_stopped() reports the old 751 * status and clears the code too; this can't race with the tracee, it 752 * takes siglock after resume. 753 */ 754 need_siglock = data && !thread_group_empty(current); 755 if (need_siglock) 756 spin_lock_irq(&child->sighand->siglock); 757 child->exit_code = data; 758 wake_up_state(child, __TASK_TRACED); 759 if (need_siglock) 760 spin_unlock_irq(&child->sighand->siglock); 761 762 return 0; 763 } 764 765 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 766 767 static const struct user_regset * 768 find_regset(const struct user_regset_view *view, unsigned int type) 769 { 770 const struct user_regset *regset; 771 int n; 772 773 for (n = 0; n < view->n; ++n) { 774 regset = view->regsets + n; 775 if (regset->core_note_type == type) 776 return regset; 777 } 778 779 return NULL; 780 } 781 782 static int ptrace_regset(struct task_struct *task, int req, unsigned int type, 783 struct iovec *kiov) 784 { 785 const struct user_regset_view *view = task_user_regset_view(task); 786 const struct user_regset *regset = find_regset(view, type); 787 int regset_no; 788 789 if (!regset || (kiov->iov_len % regset->size) != 0) 790 return -EINVAL; 791 792 regset_no = regset - view->regsets; 793 kiov->iov_len = min(kiov->iov_len, 794 (__kernel_size_t) (regset->n * regset->size)); 795 796 if (req == PTRACE_GETREGSET) 797 return copy_regset_to_user(task, view, regset_no, 0, 798 kiov->iov_len, kiov->iov_base); 799 else 800 return copy_regset_from_user(task, view, regset_no, 0, 801 kiov->iov_len, kiov->iov_base); 802 } 803 804 /* 805 * This is declared in linux/regset.h and defined in machine-dependent 806 * code. We put the export here, near the primary machine-neutral use, 807 * to ensure no machine forgets it. 808 */ 809 EXPORT_SYMBOL_GPL(task_user_regset_view); 810 #endif 811 812 int ptrace_request(struct task_struct *child, long request, 813 unsigned long addr, unsigned long data) 814 { 815 bool seized = child->ptrace & PT_SEIZED; 816 int ret = -EIO; 817 siginfo_t siginfo, *si; 818 void __user *datavp = (void __user *) data; 819 unsigned long __user *datalp = datavp; 820 unsigned long flags; 821 822 switch (request) { 823 case PTRACE_PEEKTEXT: 824 case PTRACE_PEEKDATA: 825 return generic_ptrace_peekdata(child, addr, data); 826 case PTRACE_POKETEXT: 827 case PTRACE_POKEDATA: 828 return generic_ptrace_pokedata(child, addr, data); 829 830 #ifdef PTRACE_OLDSETOPTIONS 831 case PTRACE_OLDSETOPTIONS: 832 #endif 833 case PTRACE_SETOPTIONS: 834 ret = ptrace_setoptions(child, data); 835 break; 836 case PTRACE_GETEVENTMSG: 837 ret = put_user(child->ptrace_message, datalp); 838 break; 839 840 case PTRACE_PEEKSIGINFO: 841 ret = ptrace_peek_siginfo(child, addr, data); 842 break; 843 844 case PTRACE_GETSIGINFO: 845 ret = ptrace_getsiginfo(child, &siginfo); 846 if (!ret) 847 ret = copy_siginfo_to_user(datavp, &siginfo); 848 break; 849 850 case PTRACE_SETSIGINFO: 851 if (copy_from_user(&siginfo, datavp, sizeof siginfo)) 852 ret = -EFAULT; 853 else 854 ret = ptrace_setsiginfo(child, &siginfo); 855 break; 856 857 case PTRACE_GETSIGMASK: 858 if (addr != sizeof(sigset_t)) { 859 ret = -EINVAL; 860 break; 861 } 862 863 if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t))) 864 ret = -EFAULT; 865 else 866 ret = 0; 867 868 break; 869 870 case PTRACE_SETSIGMASK: { 871 sigset_t new_set; 872 873 if (addr != sizeof(sigset_t)) { 874 ret = -EINVAL; 875 break; 876 } 877 878 if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) { 879 ret = -EFAULT; 880 break; 881 } 882 883 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 884 885 /* 886 * Every thread does recalc_sigpending() after resume, so 887 * retarget_shared_pending() and recalc_sigpending() are not 888 * called here. 889 */ 890 spin_lock_irq(&child->sighand->siglock); 891 child->blocked = new_set; 892 spin_unlock_irq(&child->sighand->siglock); 893 894 ret = 0; 895 break; 896 } 897 898 case PTRACE_INTERRUPT: 899 /* 900 * Stop tracee without any side-effect on signal or job 901 * control. At least one trap is guaranteed to happen 902 * after this request. If @child is already trapped, the 903 * current trap is not disturbed and another trap will 904 * happen after the current trap is ended with PTRACE_CONT. 905 * 906 * The actual trap might not be PTRACE_EVENT_STOP trap but 907 * the pending condition is cleared regardless. 908 */ 909 if (unlikely(!seized || !lock_task_sighand(child, &flags))) 910 break; 911 912 /* 913 * INTERRUPT doesn't disturb existing trap sans one 914 * exception. If ptracer issued LISTEN for the current 915 * STOP, this INTERRUPT should clear LISTEN and re-trap 916 * tracee into STOP. 917 */ 918 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP))) 919 ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING); 920 921 unlock_task_sighand(child, &flags); 922 ret = 0; 923 break; 924 925 case PTRACE_LISTEN: 926 /* 927 * Listen for events. Tracee must be in STOP. It's not 928 * resumed per-se but is not considered to be in TRACED by 929 * wait(2) or ptrace(2). If an async event (e.g. group 930 * stop state change) happens, tracee will enter STOP trap 931 * again. Alternatively, ptracer can issue INTERRUPT to 932 * finish listening and re-trap tracee into STOP. 933 */ 934 if (unlikely(!seized || !lock_task_sighand(child, &flags))) 935 break; 936 937 si = child->last_siginfo; 938 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) { 939 child->jobctl |= JOBCTL_LISTENING; 940 /* 941 * If NOTIFY is set, it means event happened between 942 * start of this trap and now. Trigger re-trap. 943 */ 944 if (child->jobctl & JOBCTL_TRAP_NOTIFY) 945 ptrace_signal_wake_up(child, true); 946 ret = 0; 947 } 948 unlock_task_sighand(child, &flags); 949 break; 950 951 case PTRACE_DETACH: /* detach a process that was attached. */ 952 ret = ptrace_detach(child, data); 953 break; 954 955 #ifdef CONFIG_BINFMT_ELF_FDPIC 956 case PTRACE_GETFDPIC: { 957 struct mm_struct *mm = get_task_mm(child); 958 unsigned long tmp = 0; 959 960 ret = -ESRCH; 961 if (!mm) 962 break; 963 964 switch (addr) { 965 case PTRACE_GETFDPIC_EXEC: 966 tmp = mm->context.exec_fdpic_loadmap; 967 break; 968 case PTRACE_GETFDPIC_INTERP: 969 tmp = mm->context.interp_fdpic_loadmap; 970 break; 971 default: 972 break; 973 } 974 mmput(mm); 975 976 ret = put_user(tmp, datalp); 977 break; 978 } 979 #endif 980 981 #ifdef PTRACE_SINGLESTEP 982 case PTRACE_SINGLESTEP: 983 #endif 984 #ifdef PTRACE_SINGLEBLOCK 985 case PTRACE_SINGLEBLOCK: 986 #endif 987 #ifdef PTRACE_SYSEMU 988 case PTRACE_SYSEMU: 989 case PTRACE_SYSEMU_SINGLESTEP: 990 #endif 991 case PTRACE_SYSCALL: 992 case PTRACE_CONT: 993 return ptrace_resume(child, request, data); 994 995 case PTRACE_KILL: 996 if (child->exit_state) /* already dead */ 997 return 0; 998 return ptrace_resume(child, request, SIGKILL); 999 1000 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 1001 case PTRACE_GETREGSET: 1002 case PTRACE_SETREGSET: { 1003 struct iovec kiov; 1004 struct iovec __user *uiov = datavp; 1005 1006 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) 1007 return -EFAULT; 1008 1009 if (__get_user(kiov.iov_base, &uiov->iov_base) || 1010 __get_user(kiov.iov_len, &uiov->iov_len)) 1011 return -EFAULT; 1012 1013 ret = ptrace_regset(child, request, addr, &kiov); 1014 if (!ret) 1015 ret = __put_user(kiov.iov_len, &uiov->iov_len); 1016 break; 1017 } 1018 #endif 1019 default: 1020 break; 1021 } 1022 1023 return ret; 1024 } 1025 1026 static struct task_struct *ptrace_get_task_struct(pid_t pid) 1027 { 1028 struct task_struct *child; 1029 1030 rcu_read_lock(); 1031 child = find_task_by_vpid(pid); 1032 if (child) 1033 get_task_struct(child); 1034 rcu_read_unlock(); 1035 1036 if (!child) 1037 return ERR_PTR(-ESRCH); 1038 return child; 1039 } 1040 1041 #ifndef arch_ptrace_attach 1042 #define arch_ptrace_attach(child) do { } while (0) 1043 #endif 1044 1045 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, 1046 unsigned long, data) 1047 { 1048 struct task_struct *child; 1049 long ret; 1050 1051 if (request == PTRACE_TRACEME) { 1052 ret = ptrace_traceme(); 1053 if (!ret) 1054 arch_ptrace_attach(current); 1055 goto out; 1056 } 1057 1058 child = ptrace_get_task_struct(pid); 1059 if (IS_ERR(child)) { 1060 ret = PTR_ERR(child); 1061 goto out; 1062 } 1063 1064 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { 1065 ret = ptrace_attach(child, request, addr, data); 1066 /* 1067 * Some architectures need to do book-keeping after 1068 * a ptrace attach. 1069 */ 1070 if (!ret) 1071 arch_ptrace_attach(child); 1072 goto out_put_task_struct; 1073 } 1074 1075 ret = ptrace_check_attach(child, request == PTRACE_KILL || 1076 request == PTRACE_INTERRUPT); 1077 if (ret < 0) 1078 goto out_put_task_struct; 1079 1080 ret = arch_ptrace(child, request, addr, data); 1081 if (ret || request != PTRACE_DETACH) 1082 ptrace_unfreeze_traced(child); 1083 1084 out_put_task_struct: 1085 put_task_struct(child); 1086 out: 1087 return ret; 1088 } 1089 1090 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, 1091 unsigned long data) 1092 { 1093 unsigned long tmp; 1094 int copied; 1095 1096 copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); 1097 if (copied != sizeof(tmp)) 1098 return -EIO; 1099 return put_user(tmp, (unsigned long __user *)data); 1100 } 1101 1102 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, 1103 unsigned long data) 1104 { 1105 int copied; 1106 1107 copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); 1108 return (copied == sizeof(data)) ? 0 : -EIO; 1109 } 1110 1111 #if defined CONFIG_COMPAT 1112 1113 int compat_ptrace_request(struct task_struct *child, compat_long_t request, 1114 compat_ulong_t addr, compat_ulong_t data) 1115 { 1116 compat_ulong_t __user *datap = compat_ptr(data); 1117 compat_ulong_t word; 1118 siginfo_t siginfo; 1119 int ret; 1120 1121 switch (request) { 1122 case PTRACE_PEEKTEXT: 1123 case PTRACE_PEEKDATA: 1124 ret = access_process_vm(child, addr, &word, sizeof(word), 0); 1125 if (ret != sizeof(word)) 1126 ret = -EIO; 1127 else 1128 ret = put_user(word, datap); 1129 break; 1130 1131 case PTRACE_POKETEXT: 1132 case PTRACE_POKEDATA: 1133 ret = access_process_vm(child, addr, &data, sizeof(data), 1); 1134 ret = (ret != sizeof(data) ? -EIO : 0); 1135 break; 1136 1137 case PTRACE_GETEVENTMSG: 1138 ret = put_user((compat_ulong_t) child->ptrace_message, datap); 1139 break; 1140 1141 case PTRACE_GETSIGINFO: 1142 ret = ptrace_getsiginfo(child, &siginfo); 1143 if (!ret) 1144 ret = copy_siginfo_to_user32( 1145 (struct compat_siginfo __user *) datap, 1146 &siginfo); 1147 break; 1148 1149 case PTRACE_SETSIGINFO: 1150 memset(&siginfo, 0, sizeof siginfo); 1151 if (copy_siginfo_from_user32( 1152 &siginfo, (struct compat_siginfo __user *) datap)) 1153 ret = -EFAULT; 1154 else 1155 ret = ptrace_setsiginfo(child, &siginfo); 1156 break; 1157 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 1158 case PTRACE_GETREGSET: 1159 case PTRACE_SETREGSET: 1160 { 1161 struct iovec kiov; 1162 struct compat_iovec __user *uiov = 1163 (struct compat_iovec __user *) datap; 1164 compat_uptr_t ptr; 1165 compat_size_t len; 1166 1167 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) 1168 return -EFAULT; 1169 1170 if (__get_user(ptr, &uiov->iov_base) || 1171 __get_user(len, &uiov->iov_len)) 1172 return -EFAULT; 1173 1174 kiov.iov_base = compat_ptr(ptr); 1175 kiov.iov_len = len; 1176 1177 ret = ptrace_regset(child, request, addr, &kiov); 1178 if (!ret) 1179 ret = __put_user(kiov.iov_len, &uiov->iov_len); 1180 break; 1181 } 1182 #endif 1183 1184 default: 1185 ret = ptrace_request(child, request, addr, data); 1186 } 1187 1188 return ret; 1189 } 1190 1191 COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid, 1192 compat_long_t, addr, compat_long_t, data) 1193 { 1194 struct task_struct *child; 1195 long ret; 1196 1197 if (request == PTRACE_TRACEME) { 1198 ret = ptrace_traceme(); 1199 goto out; 1200 } 1201 1202 child = ptrace_get_task_struct(pid); 1203 if (IS_ERR(child)) { 1204 ret = PTR_ERR(child); 1205 goto out; 1206 } 1207 1208 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { 1209 ret = ptrace_attach(child, request, addr, data); 1210 /* 1211 * Some architectures need to do book-keeping after 1212 * a ptrace attach. 1213 */ 1214 if (!ret) 1215 arch_ptrace_attach(child); 1216 goto out_put_task_struct; 1217 } 1218 1219 ret = ptrace_check_attach(child, request == PTRACE_KILL || 1220 request == PTRACE_INTERRUPT); 1221 if (!ret) { 1222 ret = compat_arch_ptrace(child, request, addr, data); 1223 if (ret || request != PTRACE_DETACH) 1224 ptrace_unfreeze_traced(child); 1225 } 1226 1227 out_put_task_struct: 1228 put_task_struct(child); 1229 out: 1230 return ret; 1231 } 1232 #endif /* CONFIG_COMPAT */ 1233