trace.c revision 6dfc544b6aa6703d2292be34470aebf874d78452
1/* 2 * This file is part of ltrace. 3 * Copyright (C) 2007,2011,2012 Petr Machata, Red Hat Inc. 4 * Copyright (C) 2010 Joe Damato 5 * Copyright (C) 1998,2002,2003,2004,2008,2009 Juan Cespedes 6 * Copyright (C) 2006 Ian Wienand 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License as 10 * published by the Free Software Foundation; either version 2 of the 11 * License, or (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, but 14 * WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 21 * 02110-1301 USA 22 */ 23 24#include "config.h" 25 26#include <asm/unistd.h> 27#include <sys/types.h> 28#include <sys/wait.h> 29#include <assert.h> 30#include <errno.h> 31#include <stdio.h> 32#include <stdlib.h> 33#include <string.h> 34#include <unistd.h> 35 36#ifdef HAVE_LIBSELINUX 37# include <selinux/selinux.h> 38#endif 39 40#include "linux-gnu/trace.h" 41#include "linux-gnu/trace-defs.h" 42#include "backend.h" 43#include "breakpoint.h" 44#include "debug.h" 45#include "events.h" 46#include "options.h" 47#include "proc.h" 48#include "ptrace.h" 49#include "type.h" 50 51void 52trace_fail_warning(pid_t pid) 53{ 54 /* This was adapted from GDB. */ 55#ifdef HAVE_LIBSELINUX 56 static int checked = 0; 57 if (checked) 58 return; 59 checked = 1; 60 61 /* -1 is returned for errors, 0 if it has no effect, 1 if 62 * PTRACE_ATTACH is forbidden. */ 63 if (security_get_boolean_active("deny_ptrace") == 1) 64 fprintf(stderr, 65"The SELinux boolean 'deny_ptrace' is enabled, which may prevent ltrace from\n" 66"tracing other processes. You can disable this process attach protection by\n" 67"issuing 'setsebool deny_ptrace=0' in the superuser context.\n"); 68#endif /* HAVE_LIBSELINUX */ 69} 70 71void 72trace_me(void) 73{ 74 debug(DEBUG_PROCESS, "trace_me: pid=%d", getpid()); 75 if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) { 76 perror("PTRACE_TRACEME"); 77 trace_fail_warning(getpid()); 78 exit(1); 79 } 80} 81 82/* There's a (hopefully) brief period of time after the child process 83 * forks when we can't trace it yet. Here we wait for kernel to 84 * prepare the process. */ 85int 86wait_for_proc(pid_t pid) 87{ 88 /* man ptrace: PTRACE_ATTACH attaches to the process specified 89 in pid. The child is sent a SIGSTOP, but will not 90 necessarily have stopped by the completion of this call; 91 use wait() to wait for the child to stop. */ 92 if (waitpid(pid, NULL, __WALL) != pid) { 93 perror ("trace_pid: waitpid"); 94 return -1; 95 } 96 97 return 0; 98} 99 100int 101trace_pid(pid_t pid) 102{ 103 debug(DEBUG_PROCESS, "trace_pid: pid=%d", pid); 104 /* This shouldn't emit error messages, as there are legitimate 105 * reasons that the PID can't be attached: like it may have 106 * already ended. */ 107 if (ptrace(PTRACE_ATTACH, pid, 0, 0) < 0) 108 return -1; 109 110 return wait_for_proc(pid); 111} 112 113void 114trace_set_options(struct process *proc) 115{ 116 if (proc->tracesysgood & 0x80) 117 return; 118 119 pid_t pid = proc->pid; 120 debug(DEBUG_PROCESS, "trace_set_options: pid=%d", pid); 121 122 long options = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEFORK | 123 PTRACE_O_TRACEVFORK | PTRACE_O_TRACECLONE | 124 PTRACE_O_TRACEEXEC; 125 if (ptrace(PTRACE_SETOPTIONS, pid, 0, (void *)options) < 0 && 126 ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)options) < 0) { 127 perror("PTRACE_SETOPTIONS"); 128 return; 129 } 130 proc->tracesysgood |= 0x80; 131} 132 133void 134untrace_pid(pid_t pid) { 135 debug(DEBUG_PROCESS, "untrace_pid: pid=%d", pid); 136 ptrace(PTRACE_DETACH, pid, 0, 0); 137} 138 139void 140continue_after_signal(pid_t pid, int signum) 141{ 142 debug(DEBUG_PROCESS, "continue_after_signal: pid=%d, signum=%d", 143 pid, signum); 144 ptrace(PTRACE_SYSCALL, pid, 0, (void *)(uintptr_t)signum); 145} 146 147static enum ecb_status 148event_for_pid(Event *event, void *data) 149{ 150 if (event->proc != NULL && event->proc->pid == (pid_t)(uintptr_t)data) 151 return ecb_yield; 152 return ecb_cont; 153} 154 155static int 156have_events_for(pid_t pid) 157{ 158 return each_qd_event(event_for_pid, (void *)(uintptr_t)pid) != NULL; 159} 160 161void 162continue_process(pid_t pid) 163{ 164 debug(DEBUG_PROCESS, "continue_process: pid=%d", pid); 165 166 /* Only really continue the process if there are no events in 167 the queue for this process. Otherwise just wait for the 168 other events to arrive. */ 169 if (!have_events_for(pid)) 170 /* We always trace syscalls to control fork(), 171 * clone(), execve()... */ 172 ptrace(PTRACE_SYSCALL, pid, 0, 0); 173 else 174 debug(DEBUG_PROCESS, 175 "putting off the continue, events in que."); 176} 177 178static struct pid_task * 179get_task_info(struct pid_set *pids, pid_t pid) 180{ 181 assert(pid != 0); 182 size_t i; 183 for (i = 0; i < pids->count; ++i) 184 if (pids->tasks[i].pid == pid) 185 return &pids->tasks[i]; 186 187 return NULL; 188} 189 190static struct pid_task * 191add_task_info(struct pid_set *pids, pid_t pid) 192{ 193 if (pids->count == pids->alloc) { 194 size_t ns = (2 * pids->alloc) ?: 4; 195 struct pid_task *n = realloc(pids->tasks, 196 sizeof(*pids->tasks) * ns); 197 if (n == NULL) 198 return NULL; 199 pids->tasks = n; 200 pids->alloc = ns; 201 } 202 struct pid_task * task_info = &pids->tasks[pids->count++]; 203 memset(task_info, 0, sizeof(*task_info)); 204 task_info->pid = pid; 205 return task_info; 206} 207 208static enum callback_status 209task_stopped(struct process *task, void *data) 210{ 211 enum process_status st = process_status(task->pid); 212 if (data != NULL) 213 *(enum process_status *)data = st; 214 215 /* If the task is already stopped, don't worry about it. 216 * Likewise if it managed to become a zombie or terminate in 217 * the meantime. This can happen when the whole thread group 218 * is terminating. */ 219 switch (st) { 220 case PS_INVALID: 221 case PS_TRACING_STOP: 222 case PS_ZOMBIE: 223 return CBS_CONT; 224 case PS_SLEEPING: 225 case PS_STOP: 226 case PS_OTHER: 227 return CBS_STOP; 228 } 229 230 abort (); 231} 232 233/* Task is blocked if it's stopped, or if it's a vfork parent. */ 234static enum callback_status 235task_blocked(struct process *task, void *data) 236{ 237 struct pid_set *pids = data; 238 struct pid_task *task_info = get_task_info(pids, task->pid); 239 if (task_info != NULL 240 && task_info->vforked) 241 return CBS_CONT; 242 243 return task_stopped(task, NULL); 244} 245 246static Event *process_vfork_on_event(struct event_handler *super, Event *event); 247 248static enum callback_status 249task_vforked(struct process *task, void *data) 250{ 251 if (task->event_handler != NULL 252 && task->event_handler->on_event == &process_vfork_on_event) 253 return CBS_STOP; 254 return CBS_CONT; 255} 256 257static int 258is_vfork_parent(struct process *task) 259{ 260 return each_task(task->leader, NULL, &task_vforked, NULL) != NULL; 261} 262 263static enum callback_status 264send_sigstop(struct process *task, void *data) 265{ 266 struct process *leader = task->leader; 267 struct pid_set *pids = data; 268 269 /* Look for pre-existing task record, or add new. */ 270 struct pid_task *task_info = get_task_info(pids, task->pid); 271 if (task_info == NULL) 272 task_info = add_task_info(pids, task->pid); 273 if (task_info == NULL) { 274 perror("send_sigstop: add_task_info"); 275 destroy_event_handler(leader); 276 /* Signal failure upwards. */ 277 return CBS_STOP; 278 } 279 280 /* This task still has not been attached to. It should be 281 stopped by the kernel. */ 282 if (task->state == STATE_BEING_CREATED) 283 return CBS_CONT; 284 285 /* Don't bother sending SIGSTOP if we are already stopped, or 286 * if we sent the SIGSTOP already, which happens when we are 287 * handling "onexit" and inherited the handler from breakpoint 288 * re-enablement. */ 289 enum process_status st; 290 if (task_stopped(task, &st) == CBS_CONT) 291 return CBS_CONT; 292 if (task_info->sigstopped) { 293 if (!task_info->delivered) 294 return CBS_CONT; 295 task_info->delivered = 0; 296 } 297 298 /* Also don't attempt to stop the process if it's a parent of 299 * vforked process. We set up event handler specially to hint 300 * us. In that case parent is in D state, which we use to 301 * weed out unnecessary looping. */ 302 if (st == PS_SLEEPING 303 && is_vfork_parent(task)) { 304 task_info->vforked = 1; 305 return CBS_CONT; 306 } 307 308 if (task_kill(task->pid, SIGSTOP) >= 0) { 309 debug(DEBUG_PROCESS, "send SIGSTOP to %d", task->pid); 310 task_info->sigstopped = 1; 311 } else 312 fprintf(stderr, 313 "Warning: couldn't send SIGSTOP to %d\n", task->pid); 314 315 return CBS_CONT; 316} 317 318/* On certain kernels, detaching right after a singlestep causes the 319 tracee to be killed with a SIGTRAP (that even though the singlestep 320 was properly caught by waitpid. The ugly workaround is to put a 321 breakpoint where IP points and let the process continue. After 322 this the breakpoint can be retracted and the process detached. */ 323static void 324ugly_workaround(struct process *proc) 325{ 326 void *ip = get_instruction_pointer(proc); 327 struct breakpoint *sbp = dict_find_entry(proc->leader->breakpoints, ip); 328 if (sbp != NULL) 329 enable_breakpoint(proc, sbp); 330 else 331 insert_breakpoint(proc, ip, NULL); 332 ptrace(PTRACE_CONT, proc->pid, 0, 0); 333} 334 335static void 336process_stopping_done(struct process_stopping_handler *self, 337 struct process *leader) 338{ 339 debug(DEBUG_PROCESS, "process stopping done %d", 340 self->task_enabling_breakpoint->pid); 341 342 if (!self->exiting) { 343 size_t i; 344 for (i = 0; i < self->pids.count; ++i) 345 if (self->pids.tasks[i].pid != 0 346 && (self->pids.tasks[i].delivered 347 || self->pids.tasks[i].sysret)) 348 continue_process(self->pids.tasks[i].pid); 349 continue_process(self->task_enabling_breakpoint->pid); 350 } 351 352 if (self->exiting) { 353 ugly_workaround: 354 self->state = psh_ugly_workaround; 355 ugly_workaround(self->task_enabling_breakpoint); 356 } else { 357 switch ((self->ugly_workaround_p)(self)) { 358 case CBS_FAIL: 359 /* xxx handle me */ 360 case CBS_STOP: 361 break; 362 case CBS_CONT: 363 goto ugly_workaround; 364 } 365 destroy_event_handler(leader); 366 } 367} 368 369/* Before we detach, we need to make sure that task's IP is on the 370 * edge of an instruction. So for tasks that have a breakpoint event 371 * in the queue, we adjust the instruction pointer, just like 372 * continue_after_breakpoint does. */ 373static enum ecb_status 374undo_breakpoint(Event *event, void *data) 375{ 376 if (event != NULL 377 && event->proc->leader == data 378 && event->type == EVENT_BREAKPOINT) 379 set_instruction_pointer(event->proc, event->e_un.brk_addr); 380 return ecb_cont; 381} 382 383static enum callback_status 384untrace_task(struct process *task, void *data) 385{ 386 if (task != data) 387 untrace_pid(task->pid); 388 return CBS_CONT; 389} 390 391static enum callback_status 392remove_task(struct process *task, void *data) 393{ 394 /* Don't untrace leader just yet. */ 395 if (task != data) 396 remove_process(task); 397 return CBS_CONT; 398} 399 400static enum callback_status 401retract_breakpoint_cb(struct process *proc, struct breakpoint *bp, void *data) 402{ 403 breakpoint_on_retract(bp, proc); 404 return CBS_CONT; 405} 406 407static void 408detach_process(struct process *leader) 409{ 410 each_qd_event(&undo_breakpoint, leader); 411 disable_all_breakpoints(leader); 412 proc_each_breakpoint(leader, NULL, retract_breakpoint_cb, NULL); 413 414 /* Now untrace the process, if it was attached to by -p. */ 415 struct opt_p_t *it; 416 for (it = opt_p; it != NULL; it = it->next) { 417 struct process *proc = pid2proc(it->pid); 418 if (proc == NULL) 419 continue; 420 if (proc->leader == leader) { 421 each_task(leader, NULL, &untrace_task, NULL); 422 break; 423 } 424 } 425 each_task(leader, NULL, &remove_task, leader); 426 destroy_event_handler(leader); 427 remove_task(leader, NULL); 428} 429 430static void 431handle_stopping_event(struct pid_task *task_info, Event **eventp) 432{ 433 /* Mark all events, so that we know whom to SIGCONT later. */ 434 if (task_info != NULL) 435 task_info->got_event = 1; 436 437 Event *event = *eventp; 438 439 /* In every state, sink SIGSTOP events for tasks that it was 440 * sent to. */ 441 if (task_info != NULL 442 && event->type == EVENT_SIGNAL 443 && event->e_un.signum == SIGSTOP) { 444 debug(DEBUG_PROCESS, "SIGSTOP delivered to %d", task_info->pid); 445 if (task_info->sigstopped 446 && !task_info->delivered) { 447 task_info->delivered = 1; 448 *eventp = NULL; // sink the event 449 } else 450 fprintf(stderr, "suspicious: %d got SIGSTOP, but " 451 "sigstopped=%d and delivered=%d\n", 452 task_info->pid, task_info->sigstopped, 453 task_info->delivered); 454 } 455} 456 457/* Some SIGSTOPs may have not been delivered to their respective tasks 458 * yet. They are still in the queue. If we have seen an event for 459 * that process, continue it, so that the SIGSTOP can be delivered and 460 * caught by ltrace. We don't mind that the process is after 461 * breakpoint (and therefore potentially doesn't have aligned IP), 462 * because the signal will be delivered without the process actually 463 * starting. */ 464static void 465continue_for_sigstop_delivery(struct pid_set *pids) 466{ 467 size_t i; 468 for (i = 0; i < pids->count; ++i) { 469 if (pids->tasks[i].pid != 0 470 && pids->tasks[i].sigstopped 471 && !pids->tasks[i].delivered 472 && pids->tasks[i].got_event) { 473 debug(DEBUG_PROCESS, "continue %d for SIGSTOP delivery", 474 pids->tasks[i].pid); 475 ptrace(PTRACE_SYSCALL, pids->tasks[i].pid, 0, 0); 476 } 477 } 478} 479 480static int 481event_exit_p(Event *event) 482{ 483 return event != NULL && (event->type == EVENT_EXIT 484 || event->type == EVENT_EXIT_SIGNAL); 485} 486 487static int 488event_exit_or_none_p(Event *event) 489{ 490 return event == NULL || event_exit_p(event) 491 || event->type == EVENT_NONE; 492} 493 494static int 495await_sigstop_delivery(struct pid_set *pids, struct pid_task *task_info, 496 Event *event) 497{ 498 /* If we still didn't get our SIGSTOP, continue the process 499 * and carry on. */ 500 if (event != NULL && !event_exit_or_none_p(event) 501 && task_info != NULL && task_info->sigstopped) { 502 debug(DEBUG_PROCESS, "continue %d for SIGSTOP delivery", 503 task_info->pid); 504 /* We should get the signal the first thing 505 * after this, so it should be OK to continue 506 * even if we are over a breakpoint. */ 507 ptrace(PTRACE_SYSCALL, task_info->pid, 0, 0); 508 509 } else { 510 /* If all SIGSTOPs were delivered, uninstall the 511 * handler and continue everyone. */ 512 /* XXX I suspect that we should check tasks that are 513 * still around. Is things are now, there should be a 514 * race between waiting for everyone to stop and one 515 * of the tasks exiting. */ 516 int all_clear = 1; 517 size_t i; 518 for (i = 0; i < pids->count; ++i) 519 if (pids->tasks[i].pid != 0 520 && pids->tasks[i].sigstopped 521 && !pids->tasks[i].delivered) { 522 all_clear = 0; 523 break; 524 } 525 return all_clear; 526 } 527 528 return 0; 529} 530 531static int 532all_stops_accountable(struct pid_set *pids) 533{ 534 size_t i; 535 for (i = 0; i < pids->count; ++i) 536 if (pids->tasks[i].pid != 0 537 && !pids->tasks[i].got_event 538 && !have_events_for(pids->tasks[i].pid)) 539 return 0; 540 return 1; 541} 542 543/* The protocol is: 0 for success, negative for failure, positive if 544 * default singlestep is to be used. */ 545int arch_atomic_singlestep(struct process *proc, struct breakpoint *sbp, 546 int (*add_cb)(void *addr, void *data), 547 void *add_cb_data); 548 549#ifndef ARCH_HAVE_ATOMIC_SINGLESTEP 550int 551arch_atomic_singlestep(struct process *proc, struct breakpoint *sbp, 552 int (*add_cb)(void *addr, void *data), 553 void *add_cb_data) 554{ 555 return 1; 556} 557#endif 558 559static Event *process_stopping_on_event(struct event_handler *super, 560 Event *event); 561 562static void 563remove_atomic_breakpoints(struct process *proc) 564{ 565 struct process_stopping_handler *self 566 = (void *)proc->leader->event_handler; 567 assert(self != NULL); 568 assert(self->super.on_event == process_stopping_on_event); 569 570 int ct = sizeof(self->atomic_skip_bp_addrs) 571 / sizeof(*self->atomic_skip_bp_addrs); 572 int i; 573 for (i = 0; i < ct; ++i) 574 if (self->atomic_skip_bp_addrs[i] != 0) { 575 delete_breakpoint(proc, self->atomic_skip_bp_addrs[i]); 576 self->atomic_skip_bp_addrs[i] = 0; 577 } 578} 579 580static void 581atomic_singlestep_bp_on_hit(struct breakpoint *bp, struct process *proc) 582{ 583 remove_atomic_breakpoints(proc); 584} 585 586static int 587atomic_singlestep_add_bp(void *addr, void *data) 588{ 589 struct process_stopping_handler *self = data; 590 struct process *proc = self->task_enabling_breakpoint; 591 592 int ct = sizeof(self->atomic_skip_bp_addrs) 593 / sizeof(*self->atomic_skip_bp_addrs); 594 int i; 595 for (i = 0; i < ct; ++i) 596 if (self->atomic_skip_bp_addrs[i] == 0) { 597 self->atomic_skip_bp_addrs[i] = addr; 598 static struct bp_callbacks cbs = { 599 .on_hit = atomic_singlestep_bp_on_hit, 600 }; 601 struct breakpoint *bp 602 = insert_breakpoint(proc, addr, NULL); 603 breakpoint_set_callbacks(bp, &cbs); 604 return 0; 605 } 606 607 assert(!"Too many atomic singlestep breakpoints!"); 608 abort(); 609} 610 611static int 612singlestep(struct process_stopping_handler *self) 613{ 614 struct process *proc = self->task_enabling_breakpoint; 615 616 int status = arch_atomic_singlestep(self->task_enabling_breakpoint, 617 self->breakpoint_being_enabled, 618 &atomic_singlestep_add_bp, self); 619 620 /* Propagate failure and success. */ 621 if (status <= 0) 622 return status; 623 624 /* Otherwise do the default action: singlestep. */ 625 debug(1, "PTRACE_SINGLESTEP"); 626 if (ptrace(PTRACE_SINGLESTEP, proc->pid, 0, 0)) { 627 perror("PTRACE_SINGLESTEP"); 628 return -1; 629 } 630 return 0; 631} 632 633static void 634post_singlestep(struct process_stopping_handler *self, 635 struct Event **eventp) 636{ 637 continue_for_sigstop_delivery(&self->pids); 638 639 if (*eventp != NULL && (*eventp)->type == EVENT_BREAKPOINT) 640 *eventp = NULL; // handled 641 642 struct process *proc = self->task_enabling_breakpoint; 643 644 remove_atomic_breakpoints(proc); 645 self->breakpoint_being_enabled = NULL; 646} 647 648static void 649singlestep_error(struct process_stopping_handler *self) 650{ 651 struct process *teb = self->task_enabling_breakpoint; 652 struct breakpoint *sbp = self->breakpoint_being_enabled; 653 fprintf(stderr, "%d couldn't continue when handling %s (%p) at %p\n", 654 teb->pid, breakpoint_name(sbp), sbp->addr, 655 get_instruction_pointer(teb)); 656 delete_breakpoint(teb->leader, sbp->addr); 657} 658 659static void 660pt_continue(struct process_stopping_handler *self) 661{ 662 struct process *teb = self->task_enabling_breakpoint; 663 debug(1, "PTRACE_CONT"); 664 ptrace(PTRACE_CONT, teb->pid, 0, 0); 665} 666 667static void 668pt_singlestep(struct process_stopping_handler *self) 669{ 670 if (singlestep(self) < 0) 671 singlestep_error(self); 672} 673 674static void 675disable_and(struct process_stopping_handler *self, 676 void (*do_this)(struct process_stopping_handler *self)) 677{ 678 struct process *teb = self->task_enabling_breakpoint; 679 debug(DEBUG_PROCESS, "all stopped, now singlestep/cont %d", teb->pid); 680 if (self->breakpoint_being_enabled->enabled) 681 disable_breakpoint(teb, self->breakpoint_being_enabled); 682 (do_this)(self); 683 self->state = psh_singlestep; 684} 685 686void 687linux_ptrace_disable_and_singlestep(struct process_stopping_handler *self) 688{ 689 disable_and(self, &pt_singlestep); 690} 691 692void 693linux_ptrace_disable_and_continue(struct process_stopping_handler *self) 694{ 695 disable_and(self, &pt_continue); 696} 697 698/* This event handler is installed when we are in the process of 699 * stopping the whole thread group to do the pointer re-enablement for 700 * one of the threads. We pump all events to the queue for later 701 * processing while we wait for all the threads to stop. When this 702 * happens, we let the re-enablement thread to PTRACE_SINGLESTEP, 703 * re-enable, and continue everyone. */ 704static Event * 705process_stopping_on_event(struct event_handler *super, Event *event) 706{ 707 struct process_stopping_handler *self = (void *)super; 708 struct process *task = event->proc; 709 struct process *leader = task->leader; 710 struct process *teb = self->task_enabling_breakpoint; 711 712 debug(DEBUG_PROCESS, 713 "process_stopping_on_event: pid %d; event type %d; state %d", 714 task->pid, event->type, self->state); 715 716 struct pid_task *task_info = get_task_info(&self->pids, task->pid); 717 if (task_info == NULL) 718 fprintf(stderr, "new task??? %d\n", task->pid); 719 handle_stopping_event(task_info, &event); 720 721 int state = self->state; 722 int event_to_queue = !event_exit_or_none_p(event); 723 724 /* Deactivate the entry if the task exits. */ 725 if (event_exit_p(event) && task_info != NULL) 726 task_info->pid = 0; 727 728 /* Always handle sysrets. Whether sysret occurred and what 729 * sys it rets from may need to be determined based on process 730 * stack, so we need to keep that in sync with reality. Note 731 * that we don't continue the process after the sysret is 732 * handled. See continue_after_syscall. */ 733 if (event != NULL && event->type == EVENT_SYSRET) { 734 debug(1, "%d LT_EV_SYSRET", event->proc->pid); 735 event_to_queue = 0; 736 task_info->sysret = 1; 737 } 738 739 switch (state) { 740 case psh_stopping: 741 /* If everyone is stopped, singlestep. */ 742 if (each_task(leader, NULL, &task_blocked, 743 &self->pids) == NULL) { 744 (self->on_all_stopped)(self); 745 state = self->state; 746 } 747 break; 748 749 case psh_singlestep: 750 /* In singlestep state, breakpoint signifies that we 751 * have now stepped, and can re-enable the breakpoint. */ 752 if (event != NULL && task == teb) { 753 754 /* If this was caused by a real breakpoint, as 755 * opposed to a singlestep, assume that it's 756 * an artificial breakpoint installed for some 757 * reason for the re-enablement. In that case 758 * handle it. */ 759 if (event->type == EVENT_BREAKPOINT) { 760 arch_addr_t ip 761 = get_instruction_pointer(task); 762 struct breakpoint *other 763 = address2bpstruct(leader, ip); 764 if (other != NULL) 765 breakpoint_on_hit(other, task); 766 } 767 768 /* If we got SIGNAL instead of BREAKPOINT, 769 * then this is not singlestep at all. */ 770 if (event->type == EVENT_SIGNAL) { 771 do_singlestep: 772 if (singlestep(self) < 0) { 773 singlestep_error(self); 774 post_singlestep(self, &event); 775 goto psh_sinking; 776 } 777 break; 778 } else { 779 switch ((self->keep_stepping_p)(self)) { 780 case CBS_FAIL: 781 /* XXX handle me */ 782 case CBS_STOP: 783 break; 784 case CBS_CONT: 785 /* Sink singlestep event. */ 786 if (event->type == EVENT_BREAKPOINT) 787 event = NULL; 788 goto do_singlestep; 789 } 790 } 791 792 /* Re-enable the breakpoint that we are 793 * stepping over. */ 794 struct breakpoint *sbp = self->breakpoint_being_enabled; 795 if (sbp->enabled) 796 enable_breakpoint(teb, sbp); 797 798 post_singlestep(self, &event); 799 goto psh_sinking; 800 } 801 break; 802 803 psh_sinking: 804 state = self->state = psh_sinking; 805 case psh_sinking: 806 if (await_sigstop_delivery(&self->pids, task_info, event)) 807 process_stopping_done(self, leader); 808 break; 809 810 case psh_ugly_workaround: 811 if (event == NULL) 812 break; 813 if (event->type == EVENT_BREAKPOINT) { 814 undo_breakpoint(event, leader); 815 if (task == teb) 816 self->task_enabling_breakpoint = NULL; 817 } 818 if (self->task_enabling_breakpoint == NULL 819 && all_stops_accountable(&self->pids)) { 820 undo_breakpoint(event, leader); 821 detach_process(leader); 822 event = NULL; // handled 823 } 824 } 825 826 if (event != NULL && event_to_queue) { 827 enque_event(event); 828 event = NULL; // sink the event 829 } 830 831 return event; 832} 833 834static void 835process_stopping_destroy(struct event_handler *super) 836{ 837 struct process_stopping_handler *self = (void *)super; 838 free(self->pids.tasks); 839} 840 841static enum callback_status 842no(struct process_stopping_handler *self) 843{ 844 return CBS_STOP; 845} 846 847int 848process_install_stopping_handler(struct process *proc, struct breakpoint *sbp, 849 void (*as)(struct process_stopping_handler *), 850 enum callback_status (*ks) 851 (struct process_stopping_handler *), 852 enum callback_status (*uw) 853 (struct process_stopping_handler *)) 854{ 855 debug(DEBUG_FUNCTION, 856 "process_install_stopping_handler: pid=%d", proc->pid); 857 858 struct process_stopping_handler *handler = calloc(sizeof(*handler), 1); 859 if (handler == NULL) 860 return -1; 861 862 if (as == NULL) 863 as = &linux_ptrace_disable_and_singlestep; 864 if (ks == NULL) 865 ks = &no; 866 if (uw == NULL) 867 uw = &no; 868 869 handler->super.on_event = process_stopping_on_event; 870 handler->super.destroy = process_stopping_destroy; 871 handler->task_enabling_breakpoint = proc; 872 handler->breakpoint_being_enabled = sbp; 873 handler->on_all_stopped = as; 874 handler->keep_stepping_p = ks; 875 handler->ugly_workaround_p = uw; 876 877 install_event_handler(proc->leader, &handler->super); 878 879 if (each_task(proc->leader, NULL, &send_sigstop, 880 &handler->pids) != NULL) { 881 destroy_event_handler(proc); 882 return -1; 883 } 884 885 /* And deliver the first fake event, in case all the 886 * conditions are already fulfilled. */ 887 Event ev = { 888 .type = EVENT_NONE, 889 .proc = proc, 890 }; 891 process_stopping_on_event(&handler->super, &ev); 892 893 return 0; 894} 895 896void 897continue_after_breakpoint(struct process *proc, struct breakpoint *sbp) 898{ 899 debug(DEBUG_PROCESS, 900 "continue_after_breakpoint: pid=%d, addr=%p", 901 proc->pid, sbp->addr); 902 903 set_instruction_pointer(proc, sbp->addr); 904 905 if (sbp->enabled == 0) { 906 continue_process(proc->pid); 907 } else { 908#if defined __sparc__ || defined __ia64___ 909 /* we don't want to singlestep here */ 910 continue_process(proc->pid); 911#else 912 if (process_install_stopping_handler 913 (proc, sbp, NULL, NULL, NULL) < 0) { 914 perror("process_stopping_handler_create"); 915 /* Carry on not bothering to re-enable. */ 916 continue_process(proc->pid); 917 } 918#endif 919 } 920} 921 922/** 923 * Ltrace exit. When we are about to exit, we have to go through all 924 * the processes, stop them all, remove all the breakpoints, and then 925 * detach the processes that we attached to using -p. If we left the 926 * other tasks running, they might hit stray return breakpoints and 927 * produce artifacts, so we better stop everyone, even if it's a bit 928 * of extra work. 929 */ 930struct ltrace_exiting_handler 931{ 932 struct event_handler super; 933 struct pid_set pids; 934}; 935 936static Event * 937ltrace_exiting_on_event(struct event_handler *super, Event *event) 938{ 939 struct ltrace_exiting_handler *self = (void *)super; 940 struct process *task = event->proc; 941 struct process *leader = task->leader; 942 943 debug(DEBUG_PROCESS, 944 "ltrace_exiting_on_event: pid %d; event type %d", 945 task->pid, event->type); 946 947 struct pid_task *task_info = get_task_info(&self->pids, task->pid); 948 handle_stopping_event(task_info, &event); 949 950 if (event != NULL && event->type == EVENT_BREAKPOINT) 951 undo_breakpoint(event, leader); 952 953 if (await_sigstop_delivery(&self->pids, task_info, event) 954 && all_stops_accountable(&self->pids)) 955 detach_process(leader); 956 957 /* Sink all non-exit events. We are about to exit, so we 958 * don't bother with queuing them. */ 959 if (event_exit_or_none_p(event)) 960 return event; 961 962 return NULL; 963} 964 965static void 966ltrace_exiting_destroy(struct event_handler *super) 967{ 968 struct ltrace_exiting_handler *self = (void *)super; 969 free(self->pids.tasks); 970} 971 972static int 973ltrace_exiting_install_handler(struct process *proc) 974{ 975 /* Only install to leader. */ 976 if (proc->leader != proc) 977 return 0; 978 979 /* Perhaps we are already installed, if the user passed 980 * several -p options that are tasks of one process. */ 981 if (proc->event_handler != NULL 982 && proc->event_handler->on_event == <race_exiting_on_event) 983 return 0; 984 985 /* If stopping handler is already present, let it do the 986 * work. */ 987 if (proc->event_handler != NULL) { 988 assert(proc->event_handler->on_event 989 == &process_stopping_on_event); 990 struct process_stopping_handler *other 991 = (void *)proc->event_handler; 992 other->exiting = 1; 993 return 0; 994 } 995 996 struct ltrace_exiting_handler *handler 997 = calloc(sizeof(*handler), 1); 998 if (handler == NULL) { 999 perror("malloc exiting handler"); 1000 fatal: 1001 /* XXXXXXXXXXXXXXXXXXX fixme */ 1002 return -1; 1003 } 1004 1005 handler->super.on_event = ltrace_exiting_on_event; 1006 handler->super.destroy = ltrace_exiting_destroy; 1007 install_event_handler(proc->leader, &handler->super); 1008 1009 if (each_task(proc->leader, NULL, &send_sigstop, 1010 &handler->pids) != NULL) 1011 goto fatal; 1012 1013 return 0; 1014} 1015 1016/* 1017 * When the traced process vforks, it's suspended until the child 1018 * process calls _exit or exec*. In the meantime, the two share the 1019 * address space. 1020 * 1021 * The child process should only ever call _exit or exec*, but we 1022 * can't count on that (it's not the role of ltrace to policy, but to 1023 * observe). In any case, we will _at least_ have to deal with 1024 * removal of vfork return breakpoint (which we have to smuggle back 1025 * in, so that the parent can see it, too), and introduction of exec* 1026 * return breakpoint. Since we already have both breakpoint actions 1027 * to deal with, we might as well support it all. 1028 * 1029 * The gist is that we pretend that the child is in a thread group 1030 * with its parent, and handle it as a multi-threaded case, with the 1031 * exception that we know that the parent is blocked, and don't 1032 * attempt to stop it. When the child execs, we undo the setup. 1033 */ 1034 1035struct process_vfork_handler 1036{ 1037 struct event_handler super; 1038 void *bp_addr; 1039}; 1040 1041static Event * 1042process_vfork_on_event(struct event_handler *super, Event *event) 1043{ 1044 debug(DEBUG_PROCESS, 1045 "process_vfork_on_event: pid %d; event type %d", 1046 event->proc->pid, event->type); 1047 1048 struct process_vfork_handler *self = (void *)super; 1049 struct breakpoint *sbp; 1050 assert(self != NULL); 1051 1052 switch (event->type) { 1053 case EVENT_BREAKPOINT: 1054 /* Remember the vfork return breakpoint. */ 1055 if (self->bp_addr == 0) 1056 self->bp_addr = event->e_un.brk_addr; 1057 break; 1058 1059 case EVENT_EXIT: 1060 case EVENT_EXIT_SIGNAL: 1061 case EVENT_EXEC: 1062 /* Smuggle back in the vfork return breakpoint, so 1063 * that our parent can trip over it once again. */ 1064 if (self->bp_addr != 0) { 1065 sbp = dict_find_entry(event->proc->leader->breakpoints, 1066 self->bp_addr); 1067 if (sbp != NULL) 1068 assert(sbp->libsym == NULL); 1069 /* We don't mind failing that, it's not a big 1070 * deal to not display one extra vfork return. */ 1071 insert_breakpoint(event->proc->parent, 1072 self->bp_addr, NULL); 1073 } 1074 1075 continue_process(event->proc->parent->pid); 1076 1077 /* Remove the leader that we artificially set up 1078 * earlier. */ 1079 change_process_leader(event->proc, event->proc); 1080 destroy_event_handler(event->proc); 1081 1082 default: 1083 ; 1084 } 1085 1086 return event; 1087} 1088 1089void 1090continue_after_vfork(struct process *proc) 1091{ 1092 debug(DEBUG_PROCESS, "continue_after_vfork: pid=%d", proc->pid); 1093 struct process_vfork_handler *handler = calloc(sizeof(*handler), 1); 1094 if (handler == NULL) { 1095 perror("malloc vfork handler"); 1096 /* Carry on not bothering to treat the process as 1097 * necessary. */ 1098 continue_process(proc->parent->pid); 1099 return; 1100 } 1101 1102 /* We must set up custom event handler, so that we see 1103 * exec/exit events for the task itself. */ 1104 handler->super.on_event = process_vfork_on_event; 1105 install_event_handler(proc, &handler->super); 1106 1107 /* Make sure that the child is sole thread. */ 1108 assert(proc->leader == proc); 1109 assert(proc->next == NULL || proc->next->leader != proc); 1110 1111 /* Make sure that the child's parent is properly set up. */ 1112 assert(proc->parent != NULL); 1113 assert(proc->parent->leader != NULL); 1114 1115 change_process_leader(proc, proc->parent->leader); 1116} 1117 1118static int 1119is_mid_stopping(struct process *proc) 1120{ 1121 return proc != NULL 1122 && proc->event_handler != NULL 1123 && proc->event_handler->on_event == &process_stopping_on_event; 1124} 1125 1126void 1127continue_after_syscall(struct process *proc, int sysnum, int ret_p) 1128{ 1129 /* Don't continue if we are mid-stopping. */ 1130 if (ret_p && (is_mid_stopping(proc) || is_mid_stopping(proc->leader))) { 1131 debug(DEBUG_PROCESS, 1132 "continue_after_syscall: don't continue %d", 1133 proc->pid); 1134 return; 1135 } 1136 continue_process(proc->pid); 1137} 1138 1139/* If ltrace gets SIGINT, the processes directly or indirectly run by 1140 * ltrace get it too. We just have to wait long enough for the signal 1141 * to be delivered and the process terminated, which we notice and 1142 * exit ltrace, too. So there's not much we need to do there. We 1143 * want to keep tracing those processes as usual, in case they just 1144 * SIG_IGN the SIGINT to do their shutdown etc. 1145 * 1146 * For processes ran on the background, we want to install an exit 1147 * handler that stops all the threads, removes all breakpoints, and 1148 * detaches. 1149 */ 1150void 1151os_ltrace_exiting(void) 1152{ 1153 struct opt_p_t *it; 1154 for (it = opt_p; it != NULL; it = it->next) { 1155 struct process *proc = pid2proc(it->pid); 1156 if (proc == NULL || proc->leader == NULL) 1157 continue; 1158 if (ltrace_exiting_install_handler(proc->leader) < 0) 1159 fprintf(stderr, 1160 "Couldn't install exiting handler for %d.\n", 1161 proc->pid); 1162 } 1163} 1164 1165int 1166os_ltrace_exiting_sighandler(void) 1167{ 1168 extern int linux_in_waitpid; 1169 if (linux_in_waitpid) { 1170 os_ltrace_exiting(); 1171 return 1; 1172 } 1173 return 0; 1174} 1175 1176size_t 1177umovebytes(struct process *proc, void *addr, void *laddr, size_t len) 1178{ 1179 1180 union { 1181 long a; 1182 char c[sizeof(long)]; 1183 } a; 1184 int started = 0; 1185 size_t offset = 0, bytes_read = 0; 1186 1187 while (offset < len) { 1188 a.a = ptrace(PTRACE_PEEKTEXT, proc->pid, addr + offset, 0); 1189 if (a.a == -1 && errno) { 1190 if (started && errno == EIO) 1191 return bytes_read; 1192 else 1193 return -1; 1194 } 1195 started = 1; 1196 1197 if (len - offset >= sizeof(long)) { 1198 memcpy(laddr + offset, &a.c[0], sizeof(long)); 1199 bytes_read += sizeof(long); 1200 } 1201 else { 1202 memcpy(laddr + offset, &a.c[0], len - offset); 1203 bytes_read += (len - offset); 1204 } 1205 offset += sizeof(long); 1206 } 1207 1208 return bytes_read; 1209} 1210