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 rcu_read_lock(); 43 child->ptracer_cred = get_cred(__task_cred(new_parent)); 44 rcu_read_unlock(); 45 } 46 47 /** 48 * __ptrace_unlink - unlink ptracee and restore its execution state 49 * @child: ptracee to be unlinked 50 * 51 * Remove @child from the ptrace list, move it back to the original parent, 52 * and restore the execution state so that it conforms to the group stop 53 * state. 54 * 55 * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer 56 * exiting. For PTRACE_DETACH, unless the ptracee has been killed between 57 * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED. 58 * If the ptracer is exiting, the ptracee can be in any state. 59 * 60 * After detach, the ptracee should be in a state which conforms to the 61 * group stop. If the group is stopped or in the process of stopping, the 62 * ptracee should be put into TASK_STOPPED; otherwise, it should be woken 63 * up from TASK_TRACED. 64 * 65 * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED, 66 * it goes through TRACED -> RUNNING -> STOPPED transition which is similar 67 * to but in the opposite direction of what happens while attaching to a 68 * stopped task. However, in this direction, the intermediate RUNNING 69 * state is not hidden even from the current ptracer and if it immediately 70 * re-attaches and performs a WNOHANG wait(2), it may fail. 71 * 72 * CONTEXT: 73 * write_lock_irq(tasklist_lock) 74 */ 75 void __ptrace_unlink(struct task_struct *child) 76 { 77 const struct cred *old_cred; 78 BUG_ON(!child->ptrace); 79 80 child->parent = child->real_parent; 81 list_del_init(&child->ptrace_entry); 82 old_cred = child->ptracer_cred; 83 child->ptracer_cred = NULL; 84 put_cred(old_cred); 85 86 spin_lock(&child->sighand->siglock); 87 child->ptrace = 0; 88 /* 89 * Clear all pending traps and TRAPPING. TRAPPING should be 90 * cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly. 91 */ 92 task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK); 93 task_clear_jobctl_trapping(child); 94 95 /* 96 * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and 97 * @child isn't dead. 98 */ 99 if (!(child->flags & PF_EXITING) && 100 (child->signal->flags & SIGNAL_STOP_STOPPED || 101 child->signal->group_stop_count)) { 102 child->jobctl |= JOBCTL_STOP_PENDING; 103 104 /* 105 * This is only possible if this thread was cloned by the 106 * traced task running in the stopped group, set the signal 107 * for the future reports. 108 * FIXME: we should change ptrace_init_task() to handle this 109 * case. 110 */ 111 if (!(child->jobctl & JOBCTL_STOP_SIGMASK)) 112 child->jobctl |= SIGSTOP; 113 } 114 115 /* 116 * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick 117 * @child in the butt. Note that @resume should be used iff @child 118 * is in TASK_TRACED; otherwise, we might unduly disrupt 119 * TASK_KILLABLE sleeps. 120 */ 121 if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child)) 122 ptrace_signal_wake_up(child, true); 123 124 spin_unlock(&child->sighand->siglock); 125 } 126 127 /* Ensure that nothing can wake it up, even SIGKILL */ 128 static bool ptrace_freeze_traced(struct task_struct *task) 129 { 130 bool ret = false; 131 132 /* Lockless, nobody but us can set this flag */ 133 if (task->jobctl & JOBCTL_LISTENING) 134 return ret; 135 136 spin_lock_irq(&task->sighand->siglock); 137 if (task_is_traced(task) && !__fatal_signal_pending(task)) { 138 task->state = __TASK_TRACED; 139 ret = true; 140 } 141 spin_unlock_irq(&task->sighand->siglock); 142 143 return ret; 144 } 145 146 static void ptrace_unfreeze_traced(struct task_struct *task) 147 { 148 if (task->state != __TASK_TRACED) 149 return; 150 151 WARN_ON(!task->ptrace || task->parent != current); 152 153 spin_lock_irq(&task->sighand->siglock); 154 if (__fatal_signal_pending(task)) 155 wake_up_state(task, __TASK_TRACED); 156 else 157 task->state = TASK_TRACED; 158 spin_unlock_irq(&task->sighand->siglock); 159 } 160 161 /** 162 * ptrace_check_attach - check whether ptracee is ready for ptrace operation 163 * @child: ptracee to check for 164 * @ignore_state: don't check whether @child is currently %TASK_TRACED 165 * 166 * Check whether @child is being ptraced by %current and ready for further 167 * ptrace operations. If @ignore_state is %false, @child also should be in 168 * %TASK_TRACED state and on return the child is guaranteed to be traced 169 * and not executing. If @ignore_state is %true, @child can be in any 170 * state. 171 * 172 * CONTEXT: 173 * Grabs and releases tasklist_lock and @child->sighand->siglock. 174 * 175 * RETURNS: 176 * 0 on success, -ESRCH if %child is not ready. 177 */ 178 static int ptrace_check_attach(struct task_struct *child, bool ignore_state) 179 { 180 int ret = -ESRCH; 181 182 /* 183 * We take the read lock around doing both checks to close a 184 * possible race where someone else was tracing our child and 185 * detached between these two checks. After this locked check, 186 * we are sure that this is our traced child and that can only 187 * be changed by us so it's not changing right after this. 188 */ 189 read_lock(&tasklist_lock); 190 if (child->ptrace && child->parent == current) { 191 WARN_ON(child->state == __TASK_TRACED); 192 /* 193 * child->sighand can't be NULL, release_task() 194 * does ptrace_unlink() before __exit_signal(). 195 */ 196 if (ignore_state || ptrace_freeze_traced(child)) 197 ret = 0; 198 } 199 read_unlock(&tasklist_lock); 200 201 if (!ret && !ignore_state) { 202 if (!wait_task_inactive(child, __TASK_TRACED)) { 203 /* 204 * This can only happen if may_ptrace_stop() fails and 205 * ptrace_stop() changes ->state back to TASK_RUNNING, 206 * so we should not worry about leaking __TASK_TRACED. 207 */ 208 WARN_ON(child->state == __TASK_TRACED); 209 ret = -ESRCH; 210 } 211 } 212 213 return ret; 214 } 215 216 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode) 217 { 218 if (mode & PTRACE_MODE_NOAUDIT) 219 return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE); 220 else 221 return has_ns_capability(current, ns, CAP_SYS_PTRACE); 222 } 223 224 /* Returns 0 on success, -errno on denial. */ 225 static int __ptrace_may_access(struct task_struct *task, unsigned int mode) 226 { 227 const struct cred *cred = current_cred(), *tcred; 228 struct mm_struct *mm; 229 kuid_t caller_uid; 230 kgid_t caller_gid; 231 232 if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) { 233 WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n"); 234 return -EPERM; 235 } 236 237 /* May we inspect the given task? 238 * This check is used both for attaching with ptrace 239 * and for allowing access to sensitive information in /proc. 240 * 241 * ptrace_attach denies several cases that /proc allows 242 * because setting up the necessary parent/child relationship 243 * or halting the specified task is impossible. 244 */ 245 246 /* Don't let security modules deny introspection */ 247 if (same_thread_group(task, current)) 248 return 0; 249 rcu_read_lock(); 250 if (mode & PTRACE_MODE_FSCREDS) { 251 caller_uid = cred->fsuid; 252 caller_gid = cred->fsgid; 253 } else { 254 /* 255 * Using the euid would make more sense here, but something 256 * in userland might rely on the old behavior, and this 257 * shouldn't be a security problem since 258 * PTRACE_MODE_REALCREDS implies that the caller explicitly 259 * used a syscall that requests access to another process 260 * (and not a filesystem syscall to procfs). 261 */ 262 caller_uid = cred->uid; 263 caller_gid = cred->gid; 264 } 265 tcred = __task_cred(task); 266 if (uid_eq(caller_uid, tcred->euid) && 267 uid_eq(caller_uid, tcred->suid) && 268 uid_eq(caller_uid, tcred->uid) && 269 gid_eq(caller_gid, tcred->egid) && 270 gid_eq(caller_gid, tcred->sgid) && 271 gid_eq(caller_gid, tcred->gid)) 272 goto ok; 273 if (ptrace_has_cap(tcred->user_ns, mode)) 274 goto ok; 275 rcu_read_unlock(); 276 return -EPERM; 277 ok: 278 rcu_read_unlock(); 279 mm = task->mm; 280 if (mm && 281 ((get_dumpable(mm) != SUID_DUMP_USER) && 282 !ptrace_has_cap(mm->user_ns, mode))) 283 return -EPERM; 284 285 return security_ptrace_access_check(task, mode); 286 } 287 288 bool ptrace_may_access(struct task_struct *task, unsigned int mode) 289 { 290 int err; 291 task_lock(task); 292 err = __ptrace_may_access(task, mode); 293 task_unlock(task); 294 return !err; 295 } 296 297 static int ptrace_attach(struct task_struct *task, long request, 298 unsigned long addr, 299 unsigned long flags) 300 { 301 bool seize = (request == PTRACE_SEIZE); 302 int retval; 303 304 retval = -EIO; 305 if (seize) { 306 if (addr != 0) 307 goto out; 308 if (flags & ~(unsigned long)PTRACE_O_MASK) 309 goto out; 310 flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT); 311 } else { 312 flags = PT_PTRACED; 313 } 314 315 audit_ptrace(task); 316 317 retval = -EPERM; 318 if (unlikely(task->flags & PF_KTHREAD)) 319 goto out; 320 if (same_thread_group(task, current)) 321 goto out; 322 323 /* 324 * Protect exec's credential calculations against our interference; 325 * SUID, SGID and LSM creds get determined differently 326 * under ptrace. 327 */ 328 retval = -ERESTARTNOINTR; 329 if (mutex_lock_interruptible(&task->signal->cred_guard_mutex)) 330 goto out; 331 332 task_lock(task); 333 retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); 334 task_unlock(task); 335 if (retval) 336 goto unlock_creds; 337 338 write_lock_irq(&tasklist_lock); 339 retval = -EPERM; 340 if (unlikely(task->exit_state)) 341 goto unlock_tasklist; 342 if (task->ptrace) 343 goto unlock_tasklist; 344 345 if (seize) 346 flags |= PT_SEIZED; 347 task->ptrace = flags; 348 349 __ptrace_link(task, current); 350 351 /* SEIZE doesn't trap tracee on attach */ 352 if (!seize) 353 send_sig_info(SIGSTOP, SEND_SIG_FORCED, task); 354 355 spin_lock(&task->sighand->siglock); 356 357 /* 358 * If the task is already STOPPED, set JOBCTL_TRAP_STOP and 359 * TRAPPING, and kick it so that it transits to TRACED. TRAPPING 360 * will be cleared if the child completes the transition or any 361 * event which clears the group stop states happens. We'll wait 362 * for the transition to complete before returning from this 363 * function. 364 * 365 * This hides STOPPED -> RUNNING -> TRACED transition from the 366 * attaching thread but a different thread in the same group can 367 * still observe the transient RUNNING state. IOW, if another 368 * thread's WNOHANG wait(2) on the stopped tracee races against 369 * ATTACH, the wait(2) may fail due to the transient RUNNING. 370 * 371 * The following task_is_stopped() test is safe as both transitions 372 * in and out of STOPPED are protected by siglock. 373 */ 374 if (task_is_stopped(task) && 375 task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) 376 signal_wake_up_state(task, __TASK_STOPPED); 377 378 spin_unlock(&task->sighand->siglock); 379 380 retval = 0; 381 unlock_tasklist: 382 write_unlock_irq(&tasklist_lock); 383 unlock_creds: 384 mutex_unlock(&task->signal->cred_guard_mutex); 385 out: 386 if (!retval) { 387 /* 388 * We do not bother to change retval or clear JOBCTL_TRAPPING 389 * if wait_on_bit() was interrupted by SIGKILL. The tracer will 390 * not return to user-mode, it will exit and clear this bit in 391 * __ptrace_unlink() if it wasn't already cleared by the tracee; 392 * and until then nobody can ptrace this task. 393 */ 394 wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE); 395 proc_ptrace_connector(task, PTRACE_ATTACH); 396 } 397 398 return retval; 399 } 400 401 /** 402 * ptrace_traceme -- helper for PTRACE_TRACEME 403 * 404 * Performs checks and sets PT_PTRACED. 405 * Should be used by all ptrace implementations for PTRACE_TRACEME. 406 */ 407 static int ptrace_traceme(void) 408 { 409 int ret = -EPERM; 410 411 write_lock_irq(&tasklist_lock); 412 /* Are we already being traced? */ 413 if (!current->ptrace) { 414 ret = security_ptrace_traceme(current->parent); 415 /* 416 * Check PF_EXITING to ensure ->real_parent has not passed 417 * exit_ptrace(). Otherwise we don't report the error but 418 * pretend ->real_parent untraces us right after return. 419 */ 420 if (!ret && !(current->real_parent->flags & PF_EXITING)) { 421 current->ptrace = PT_PTRACED; 422 __ptrace_link(current, current->real_parent); 423 } 424 } 425 write_unlock_irq(&tasklist_lock); 426 427 return ret; 428 } 429 430 /* 431 * Called with irqs disabled, returns true if childs should reap themselves. 432 */ 433 static int ignoring_children(struct sighand_struct *sigh) 434 { 435 int ret; 436 spin_lock(&sigh->siglock); 437 ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) || 438 (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT); 439 spin_unlock(&sigh->siglock); 440 return ret; 441 } 442 443 /* 444 * Called with tasklist_lock held for writing. 445 * Unlink a traced task, and clean it up if it was a traced zombie. 446 * Return true if it needs to be reaped with release_task(). 447 * (We can't call release_task() here because we already hold tasklist_lock.) 448 * 449 * If it's a zombie, our attachedness prevented normal parent notification 450 * or self-reaping. Do notification now if it would have happened earlier. 451 * If it should reap itself, return true. 452 * 453 * If it's our own child, there is no notification to do. But if our normal 454 * children self-reap, then this child was prevented by ptrace and we must 455 * reap it now, in that case we must also wake up sub-threads sleeping in 456 * do_wait(). 457 */ 458 static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) 459 { 460 bool dead; 461 462 __ptrace_unlink(p); 463 464 if (p->exit_state != EXIT_ZOMBIE) 465 return false; 466 467 dead = !thread_group_leader(p); 468 469 if (!dead && thread_group_empty(p)) { 470 if (!same_thread_group(p->real_parent, tracer)) 471 dead = do_notify_parent(p, p->exit_signal); 472 else if (ignoring_children(tracer->sighand)) { 473 __wake_up_parent(p, tracer); 474 dead = true; 475 } 476 } 477 /* Mark it as in the process of being reaped. */ 478 if (dead) 479 p->exit_state = EXIT_DEAD; 480 return dead; 481 } 482 483 static int ptrace_detach(struct task_struct *child, unsigned int data) 484 { 485 if (!valid_signal(data)) 486 return -EIO; 487 488 /* Architecture-specific hardware disable .. */ 489 ptrace_disable(child); 490 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 491 492 write_lock_irq(&tasklist_lock); 493 /* 494 * We rely on ptrace_freeze_traced(). It can't be killed and 495 * untraced by another thread, it can't be a zombie. 496 */ 497 WARN_ON(!child->ptrace || child->exit_state); 498 /* 499 * tasklist_lock avoids the race with wait_task_stopped(), see 500 * the comment in ptrace_resume(). 501 */ 502 child->exit_code = data; 503 __ptrace_detach(current, child); 504 write_unlock_irq(&tasklist_lock); 505 506 proc_ptrace_connector(child, PTRACE_DETACH); 507 508 return 0; 509 } 510 511 /* 512 * Detach all tasks we were using ptrace on. Called with tasklist held 513 * for writing. 514 */ 515 void exit_ptrace(struct task_struct *tracer, struct list_head *dead) 516 { 517 struct task_struct *p, *n; 518 519 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) { 520 if (unlikely(p->ptrace & PT_EXITKILL)) 521 send_sig_info(SIGKILL, SEND_SIG_FORCED, p); 522 523 if (__ptrace_detach(tracer, p)) 524 list_add(&p->ptrace_entry, dead); 525 } 526 } 527 528 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) 529 { 530 int copied = 0; 531 532 while (len > 0) { 533 char buf[128]; 534 int this_len, retval; 535 536 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 537 retval = access_process_vm(tsk, src, buf, this_len, 0); 538 if (!retval) { 539 if (copied) 540 break; 541 return -EIO; 542 } 543 if (copy_to_user(dst, buf, retval)) 544 return -EFAULT; 545 copied += retval; 546 src += retval; 547 dst += retval; 548 len -= retval; 549 } 550 return copied; 551 } 552 553 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) 554 { 555 int copied = 0; 556 557 while (len > 0) { 558 char buf[128]; 559 int this_len, retval; 560 561 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 562 if (copy_from_user(buf, src, this_len)) 563 return -EFAULT; 564 retval = access_process_vm(tsk, dst, buf, this_len, 1); 565 if (!retval) { 566 if (copied) 567 break; 568 return -EIO; 569 } 570 copied += retval; 571 src += retval; 572 dst += retval; 573 len -= retval; 574 } 575 return copied; 576 } 577 578 static int ptrace_setoptions(struct task_struct *child, unsigned long data) 579 { 580 unsigned flags; 581 582 if (data & ~(unsigned long)PTRACE_O_MASK) 583 return -EINVAL; 584 585 if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) { 586 if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) || 587 !IS_ENABLED(CONFIG_SECCOMP)) 588 return -EINVAL; 589 590 if (!capable(CAP_SYS_ADMIN)) 591 return -EPERM; 592 593 if (seccomp_mode(¤t->seccomp) != SECCOMP_MODE_DISABLED || 594 current->ptrace & PT_SUSPEND_SECCOMP) 595 return -EPERM; 596 } 597 598 /* Avoid intermediate state when all opts are cleared */ 599 flags = child->ptrace; 600 flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT); 601 flags |= (data << PT_OPT_FLAG_SHIFT); 602 child->ptrace = flags; 603 604 return 0; 605 } 606 607 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info) 608 { 609 unsigned long flags; 610 int error = -ESRCH; 611 612 if (lock_task_sighand(child, &flags)) { 613 error = -EINVAL; 614 if (likely(child->last_siginfo != NULL)) { 615 *info = *child->last_siginfo; 616 error = 0; 617 } 618 unlock_task_sighand(child, &flags); 619 } 620 return error; 621 } 622 623 static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info) 624 { 625 unsigned long flags; 626 int error = -ESRCH; 627 628 if (lock_task_sighand(child, &flags)) { 629 error = -EINVAL; 630 if (likely(child->last_siginfo != NULL)) { 631 *child->last_siginfo = *info; 632 error = 0; 633 } 634 unlock_task_sighand(child, &flags); 635 } 636 return error; 637 } 638 639 static int ptrace_peek_siginfo(struct task_struct *child, 640 unsigned long addr, 641 unsigned long data) 642 { 643 struct ptrace_peeksiginfo_args arg; 644 struct sigpending *pending; 645 struct sigqueue *q; 646 int ret, i; 647 648 ret = copy_from_user(&arg, (void __user *) addr, 649 sizeof(struct ptrace_peeksiginfo_args)); 650 if (ret) 651 return -EFAULT; 652 653 if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED) 654 return -EINVAL; /* unknown flags */ 655 656 if (arg.nr < 0) 657 return -EINVAL; 658 659 if (arg.flags & PTRACE_PEEKSIGINFO_SHARED) 660 pending = &child->signal->shared_pending; 661 else 662 pending = &child->pending; 663 664 for (i = 0; i < arg.nr; ) { 665 siginfo_t info; 666 s32 off = arg.off + i; 667 668 spin_lock_irq(&child->sighand->siglock); 669 list_for_each_entry(q, &pending->list, list) { 670 if (!off--) { 671 copy_siginfo(&info, &q->info); 672 break; 673 } 674 } 675 spin_unlock_irq(&child->sighand->siglock); 676 677 if (off >= 0) /* beyond the end of the list */ 678 break; 679 680 #ifdef CONFIG_COMPAT 681 if (unlikely(in_compat_syscall())) { 682 compat_siginfo_t __user *uinfo = compat_ptr(data); 683 684 if (copy_siginfo_to_user32(uinfo, &info) || 685 __put_user(info.si_code, &uinfo->si_code)) { 686 ret = -EFAULT; 687 break; 688 } 689 690 } else 691 #endif 692 { 693 siginfo_t __user *uinfo = (siginfo_t __user *) data; 694 695 if (copy_siginfo_to_user(uinfo, &info) || 696 __put_user(info.si_code, &uinfo->si_code)) { 697 ret = -EFAULT; 698 break; 699 } 700 } 701 702 data += sizeof(siginfo_t); 703 i++; 704 705 if (signal_pending(current)) 706 break; 707 708 cond_resched(); 709 } 710 711 if (i > 0) 712 return i; 713 714 return ret; 715 } 716 717 #ifdef PTRACE_SINGLESTEP 718 #define is_singlestep(request) ((request) == PTRACE_SINGLESTEP) 719 #else 720 #define is_singlestep(request) 0 721 #endif 722 723 #ifdef PTRACE_SINGLEBLOCK 724 #define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK) 725 #else 726 #define is_singleblock(request) 0 727 #endif 728 729 #ifdef PTRACE_SYSEMU 730 #define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP) 731 #else 732 #define is_sysemu_singlestep(request) 0 733 #endif 734 735 static int ptrace_resume(struct task_struct *child, long request, 736 unsigned long data) 737 { 738 bool need_siglock; 739 740 if (!valid_signal(data)) 741 return -EIO; 742 743 if (request == PTRACE_SYSCALL) 744 set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 745 else 746 clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); 747 748 #ifdef TIF_SYSCALL_EMU 749 if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP) 750 set_tsk_thread_flag(child, TIF_SYSCALL_EMU); 751 else 752 clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); 753 #endif 754 755 if (is_singleblock(request)) { 756 if (unlikely(!arch_has_block_step())) 757 return -EIO; 758 user_enable_block_step(child); 759 } else if (is_singlestep(request) || is_sysemu_singlestep(request)) { 760 if (unlikely(!arch_has_single_step())) 761 return -EIO; 762 user_enable_single_step(child); 763 } else { 764 user_disable_single_step(child); 765 } 766 767 /* 768 * Change ->exit_code and ->state under siglock to avoid the race 769 * with wait_task_stopped() in between; a non-zero ->exit_code will 770 * wrongly look like another report from tracee. 771 * 772 * Note that we need siglock even if ->exit_code == data and/or this 773 * status was not reported yet, the new status must not be cleared by 774 * wait_task_stopped() after resume. 775 * 776 * If data == 0 we do not care if wait_task_stopped() reports the old 777 * status and clears the code too; this can't race with the tracee, it 778 * takes siglock after resume. 779 */ 780 need_siglock = data && !thread_group_empty(current); 781 if (need_siglock) 782 spin_lock_irq(&child->sighand->siglock); 783 child->exit_code = data; 784 wake_up_state(child, __TASK_TRACED); 785 if (need_siglock) 786 spin_unlock_irq(&child->sighand->siglock); 787 788 return 0; 789 } 790 791 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 792 793 static const struct user_regset * 794 find_regset(const struct user_regset_view *view, unsigned int type) 795 { 796 const struct user_regset *regset; 797 int n; 798 799 for (n = 0; n < view->n; ++n) { 800 regset = view->regsets + n; 801 if (regset->core_note_type == type) 802 return regset; 803 } 804 805 return NULL; 806 } 807 808 static int ptrace_regset(struct task_struct *task, int req, unsigned int type, 809 struct iovec *kiov) 810 { 811 const struct user_regset_view *view = task_user_regset_view(task); 812 const struct user_regset *regset = find_regset(view, type); 813 int regset_no; 814 815 if (!regset || (kiov->iov_len % regset->size) != 0) 816 return -EINVAL; 817 818 regset_no = regset - view->regsets; 819 kiov->iov_len = min(kiov->iov_len, 820 (__kernel_size_t) (regset->n * regset->size)); 821 822 if (req == PTRACE_GETREGSET) 823 return copy_regset_to_user(task, view, regset_no, 0, 824 kiov->iov_len, kiov->iov_base); 825 else 826 return copy_regset_from_user(task, view, regset_no, 0, 827 kiov->iov_len, kiov->iov_base); 828 } 829 830 /* 831 * This is declared in linux/regset.h and defined in machine-dependent 832 * code. We put the export here, near the primary machine-neutral use, 833 * to ensure no machine forgets it. 834 */ 835 EXPORT_SYMBOL_GPL(task_user_regset_view); 836 #endif 837 838 int ptrace_request(struct task_struct *child, long request, 839 unsigned long addr, unsigned long data) 840 { 841 bool seized = child->ptrace & PT_SEIZED; 842 int ret = -EIO; 843 siginfo_t siginfo, *si; 844 void __user *datavp = (void __user *) data; 845 unsigned long __user *datalp = datavp; 846 unsigned long flags; 847 848 switch (request) { 849 case PTRACE_PEEKTEXT: 850 case PTRACE_PEEKDATA: 851 return generic_ptrace_peekdata(child, addr, data); 852 case PTRACE_POKETEXT: 853 case PTRACE_POKEDATA: 854 return generic_ptrace_pokedata(child, addr, data); 855 856 #ifdef PTRACE_OLDSETOPTIONS 857 case PTRACE_OLDSETOPTIONS: 858 #endif 859 case PTRACE_SETOPTIONS: 860 ret = ptrace_setoptions(child, data); 861 break; 862 case PTRACE_GETEVENTMSG: 863 ret = put_user(child->ptrace_message, datalp); 864 break; 865 866 case PTRACE_PEEKSIGINFO: 867 ret = ptrace_peek_siginfo(child, addr, data); 868 break; 869 870 case PTRACE_GETSIGINFO: 871 ret = ptrace_getsiginfo(child, &siginfo); 872 if (!ret) 873 ret = copy_siginfo_to_user(datavp, &siginfo); 874 break; 875 876 case PTRACE_SETSIGINFO: 877 if (copy_from_user(&siginfo, datavp, sizeof siginfo)) 878 ret = -EFAULT; 879 else 880 ret = ptrace_setsiginfo(child, &siginfo); 881 break; 882 883 case PTRACE_GETSIGMASK: 884 if (addr != sizeof(sigset_t)) { 885 ret = -EINVAL; 886 break; 887 } 888 889 if (copy_to_user(datavp, &child->blocked, sizeof(sigset_t))) 890 ret = -EFAULT; 891 else 892 ret = 0; 893 894 break; 895 896 case PTRACE_SETSIGMASK: { 897 sigset_t new_set; 898 899 if (addr != sizeof(sigset_t)) { 900 ret = -EINVAL; 901 break; 902 } 903 904 if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) { 905 ret = -EFAULT; 906 break; 907 } 908 909 sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); 910 911 /* 912 * Every thread does recalc_sigpending() after resume, so 913 * retarget_shared_pending() and recalc_sigpending() are not 914 * called here. 915 */ 916 spin_lock_irq(&child->sighand->siglock); 917 child->blocked = new_set; 918 spin_unlock_irq(&child->sighand->siglock); 919 920 ret = 0; 921 break; 922 } 923 924 case PTRACE_INTERRUPT: 925 /* 926 * Stop tracee without any side-effect on signal or job 927 * control. At least one trap is guaranteed to happen 928 * after this request. If @child is already trapped, the 929 * current trap is not disturbed and another trap will 930 * happen after the current trap is ended with PTRACE_CONT. 931 * 932 * The actual trap might not be PTRACE_EVENT_STOP trap but 933 * the pending condition is cleared regardless. 934 */ 935 if (unlikely(!seized || !lock_task_sighand(child, &flags))) 936 break; 937 938 /* 939 * INTERRUPT doesn't disturb existing trap sans one 940 * exception. If ptracer issued LISTEN for the current 941 * STOP, this INTERRUPT should clear LISTEN and re-trap 942 * tracee into STOP. 943 */ 944 if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP))) 945 ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING); 946 947 unlock_task_sighand(child, &flags); 948 ret = 0; 949 break; 950 951 case PTRACE_LISTEN: 952 /* 953 * Listen for events. Tracee must be in STOP. It's not 954 * resumed per-se but is not considered to be in TRACED by 955 * wait(2) or ptrace(2). If an async event (e.g. group 956 * stop state change) happens, tracee will enter STOP trap 957 * again. Alternatively, ptracer can issue INTERRUPT to 958 * finish listening and re-trap tracee into STOP. 959 */ 960 if (unlikely(!seized || !lock_task_sighand(child, &flags))) 961 break; 962 963 si = child->last_siginfo; 964 if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) { 965 child->jobctl |= JOBCTL_LISTENING; 966 /* 967 * If NOTIFY is set, it means event happened between 968 * start of this trap and now. Trigger re-trap. 969 */ 970 if (child->jobctl & JOBCTL_TRAP_NOTIFY) 971 ptrace_signal_wake_up(child, true); 972 ret = 0; 973 } 974 unlock_task_sighand(child, &flags); 975 break; 976 977 case PTRACE_DETACH: /* detach a process that was attached. */ 978 ret = ptrace_detach(child, data); 979 break; 980 981 #ifdef CONFIG_BINFMT_ELF_FDPIC 982 case PTRACE_GETFDPIC: { 983 struct mm_struct *mm = get_task_mm(child); 984 unsigned long tmp = 0; 985 986 ret = -ESRCH; 987 if (!mm) 988 break; 989 990 switch (addr) { 991 case PTRACE_GETFDPIC_EXEC: 992 tmp = mm->context.exec_fdpic_loadmap; 993 break; 994 case PTRACE_GETFDPIC_INTERP: 995 tmp = mm->context.interp_fdpic_loadmap; 996 break; 997 default: 998 break; 999 } 1000 mmput(mm); 1001 1002 ret = put_user(tmp, datalp); 1003 break; 1004 } 1005 #endif 1006 1007 #ifdef PTRACE_SINGLESTEP 1008 case PTRACE_SINGLESTEP: 1009 #endif 1010 #ifdef PTRACE_SINGLEBLOCK 1011 case PTRACE_SINGLEBLOCK: 1012 #endif 1013 #ifdef PTRACE_SYSEMU 1014 case PTRACE_SYSEMU: 1015 case PTRACE_SYSEMU_SINGLESTEP: 1016 #endif 1017 case PTRACE_SYSCALL: 1018 case PTRACE_CONT: 1019 return ptrace_resume(child, request, data); 1020 1021 case PTRACE_KILL: 1022 if (child->exit_state) /* already dead */ 1023 return 0; 1024 return ptrace_resume(child, request, SIGKILL); 1025 1026 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 1027 case PTRACE_GETREGSET: 1028 case PTRACE_SETREGSET: { 1029 struct iovec kiov; 1030 struct iovec __user *uiov = datavp; 1031 1032 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) 1033 return -EFAULT; 1034 1035 if (__get_user(kiov.iov_base, &uiov->iov_base) || 1036 __get_user(kiov.iov_len, &uiov->iov_len)) 1037 return -EFAULT; 1038 1039 ret = ptrace_regset(child, request, addr, &kiov); 1040 if (!ret) 1041 ret = __put_user(kiov.iov_len, &uiov->iov_len); 1042 break; 1043 } 1044 #endif 1045 1046 case PTRACE_SECCOMP_GET_FILTER: 1047 ret = seccomp_get_filter(child, addr, datavp); 1048 break; 1049 1050 default: 1051 break; 1052 } 1053 1054 return ret; 1055 } 1056 1057 static struct task_struct *ptrace_get_task_struct(pid_t pid) 1058 { 1059 struct task_struct *child; 1060 1061 rcu_read_lock(); 1062 child = find_task_by_vpid(pid); 1063 if (child) 1064 get_task_struct(child); 1065 rcu_read_unlock(); 1066 1067 if (!child) 1068 return ERR_PTR(-ESRCH); 1069 return child; 1070 } 1071 1072 #ifndef arch_ptrace_attach 1073 #define arch_ptrace_attach(child) do { } while (0) 1074 #endif 1075 1076 SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, 1077 unsigned long, data) 1078 { 1079 struct task_struct *child; 1080 long ret; 1081 { 1082 const int rc = ccs_ptrace_permission(request, pid); 1083 if (rc) 1084 return rc; 1085 } 1086 1087 if (request == PTRACE_TRACEME) { 1088 ret = ptrace_traceme(); 1089 if (!ret) 1090 arch_ptrace_attach(current); 1091 goto out; 1092 } 1093 1094 child = ptrace_get_task_struct(pid); 1095 if (IS_ERR(child)) { 1096 ret = PTR_ERR(child); 1097 goto out; 1098 } 1099 1100 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { 1101 ret = ptrace_attach(child, request, addr, data); 1102 /* 1103 * Some architectures need to do book-keeping after 1104 * a ptrace attach. 1105 */ 1106 if (!ret) 1107 arch_ptrace_attach(child); 1108 goto out_put_task_struct; 1109 } 1110 1111 ret = ptrace_check_attach(child, request == PTRACE_KILL || 1112 request == PTRACE_INTERRUPT); 1113 if (ret < 0) 1114 goto out_put_task_struct; 1115 1116 ret = arch_ptrace(child, request, addr, data); 1117 if (ret || request != PTRACE_DETACH) 1118 ptrace_unfreeze_traced(child); 1119 1120 out_put_task_struct: 1121 put_task_struct(child); 1122 out: 1123 return ret; 1124 } 1125 1126 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, 1127 unsigned long data) 1128 { 1129 unsigned long tmp; 1130 int copied; 1131 1132 copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); 1133 if (copied != sizeof(tmp)) 1134 return -EIO; 1135 return put_user(tmp, (unsigned long __user *)data); 1136 } 1137 1138 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, 1139 unsigned long data) 1140 { 1141 int copied; 1142 1143 copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); 1144 return (copied == sizeof(data)) ? 0 : -EIO; 1145 } 1146 1147 #if defined CONFIG_COMPAT 1148 1149 int compat_ptrace_request(struct task_struct *child, compat_long_t request, 1150 compat_ulong_t addr, compat_ulong_t data) 1151 { 1152 compat_ulong_t __user *datap = compat_ptr(data); 1153 compat_ulong_t word; 1154 siginfo_t siginfo; 1155 int ret; 1156 1157 switch (request) { 1158 case PTRACE_PEEKTEXT: 1159 case PTRACE_PEEKDATA: 1160 ret = access_process_vm(child, addr, &word, sizeof(word), 0); 1161 if (ret != sizeof(word)) 1162 ret = -EIO; 1163 else 1164 ret = put_user(word, datap); 1165 break; 1166 1167 case PTRACE_POKETEXT: 1168 case PTRACE_POKEDATA: 1169 ret = access_process_vm(child, addr, &data, sizeof(data), 1); 1170 ret = (ret != sizeof(data) ? -EIO : 0); 1171 break; 1172 1173 case PTRACE_GETEVENTMSG: 1174 ret = put_user((compat_ulong_t) child->ptrace_message, datap); 1175 break; 1176 1177 case PTRACE_GETSIGINFO: 1178 ret = ptrace_getsiginfo(child, &siginfo); 1179 if (!ret) 1180 ret = copy_siginfo_to_user32( 1181 (struct compat_siginfo __user *) datap, 1182 &siginfo); 1183 break; 1184 1185 case PTRACE_SETSIGINFO: 1186 memset(&siginfo, 0, sizeof siginfo); 1187 if (copy_siginfo_from_user32( 1188 &siginfo, (struct compat_siginfo __user *) datap)) 1189 ret = -EFAULT; 1190 else 1191 ret = ptrace_setsiginfo(child, &siginfo); 1192 break; 1193 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK 1194 case PTRACE_GETREGSET: 1195 case PTRACE_SETREGSET: 1196 { 1197 struct iovec kiov; 1198 struct compat_iovec __user *uiov = 1199 (struct compat_iovec __user *) datap; 1200 compat_uptr_t ptr; 1201 compat_size_t len; 1202 1203 if (!access_ok(VERIFY_WRITE, uiov, sizeof(*uiov))) 1204 return -EFAULT; 1205 1206 if (__get_user(ptr, &uiov->iov_base) || 1207 __get_user(len, &uiov->iov_len)) 1208 return -EFAULT; 1209 1210 kiov.iov_base = compat_ptr(ptr); 1211 kiov.iov_len = len; 1212 1213 ret = ptrace_regset(child, request, addr, &kiov); 1214 if (!ret) 1215 ret = __put_user(kiov.iov_len, &uiov->iov_len); 1216 break; 1217 } 1218 #endif 1219 1220 default: 1221 ret = ptrace_request(child, request, addr, data); 1222 } 1223 1224 return ret; 1225 } 1226 1227 COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid, 1228 compat_long_t, addr, compat_long_t, data) 1229 { 1230 struct task_struct *child; 1231 long ret; 1232 { 1233 const int rc = ccs_ptrace_permission(request, pid); 1234 if (rc) 1235 return rc; 1236 } 1237 1238 if (request == PTRACE_TRACEME) { 1239 ret = ptrace_traceme(); 1240 goto out; 1241 } 1242 1243 child = ptrace_get_task_struct(pid); 1244 if (IS_ERR(child)) { 1245 ret = PTR_ERR(child); 1246 goto out; 1247 } 1248 1249 if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { 1250 ret = ptrace_attach(child, request, addr, data); 1251 /* 1252 * Some architectures need to do book-keeping after 1253 * a ptrace attach. 1254 */ 1255 if (!ret) 1256 arch_ptrace_attach(child); 1257 goto out_put_task_struct; 1258 } 1259 1260 ret = ptrace_check_attach(child, request == PTRACE_KILL || 1261 request == PTRACE_INTERRUPT); 1262 if (!ret) { 1263 ret = compat_arch_ptrace(child, request, addr, data); 1264 if (ret || request != PTRACE_DETACH) 1265 ptrace_unfreeze_traced(child); 1266 } 1267 1268 out_put_task_struct: 1269 put_task_struct(child); 1270 out: 1271 return ret; 1272 } 1273 #endif /* CONFIG_COMPAT */ 1274
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