strace.c revision 38cfe7c92328e940c71074c9b579b5bf9f2cb2f6
1/* 2 * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl> 3 * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl> 4 * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com> 5 * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#include "defs.h" 32#include <stdarg.h> 33#include <sys/param.h> 34#include <fcntl.h> 35#include <sys/resource.h> 36#include <sys/wait.h> 37#include <sys/stat.h> 38#include <pwd.h> 39#include <grp.h> 40#include <dirent.h> 41#include <sys/utsname.h> 42#if defined(IA64) 43# include <asm/ptrace_offsets.h> 44#endif 45/* In some libc, these aren't declared. Do it ourself: */ 46extern char **environ; 47extern int optind; 48extern char *optarg; 49 50 51#if defined __NR_tkill 52# define my_tkill(tid, sig) syscall(__NR_tkill, (tid), (sig)) 53#else 54 /* kill() may choose arbitrarily the target task of the process group 55 while we later wait on a that specific TID. PID process waits become 56 TID task specific waits for a process under ptrace(2). */ 57# warning "tkill(2) not available, risk of strace hangs!" 58# define my_tkill(tid, sig) kill((tid), (sig)) 59#endif 60 61/* Glue for systems without a MMU that cannot provide fork() */ 62#if !defined(HAVE_FORK) 63# undef NOMMU_SYSTEM 64# define NOMMU_SYSTEM 1 65#endif 66#if NOMMU_SYSTEM 67# define fork() vfork() 68#endif 69 70cflag_t cflag = CFLAG_NONE; 71unsigned int followfork = 0; 72unsigned int ptrace_setoptions = 0; 73unsigned int xflag = 0; 74bool need_fork_exec_workarounds = 0; 75bool debug_flag = 0; 76bool Tflag = 0; 77bool qflag = 0; 78/* Which WSTOPSIG(status) value marks syscall traps? */ 79static unsigned int syscall_trap_sig = SIGTRAP; 80static unsigned int tflag = 0; 81static bool iflag = 0; 82static bool rflag = 0; 83static bool print_pid_pfx = 0; 84 85/* -I n */ 86enum { 87 INTR_NOT_SET = 0, 88 INTR_ANYWHERE = 1, /* don't block/ignore any signals */ 89 INTR_WHILE_WAIT = 2, /* block fatal signals while decoding syscall. default */ 90 INTR_NEVER = 3, /* block fatal signals. default if '-o FILE PROG' */ 91 INTR_BLOCK_TSTP_TOO = 4, /* block fatal signals and SIGTSTP (^Z) */ 92 NUM_INTR_OPTS 93}; 94static int opt_intr; 95/* We play with signal mask only if this mode is active: */ 96#define interactive (opt_intr == INTR_WHILE_WAIT) 97 98/* 99 * daemonized_tracer supports -D option. 100 * With this option, strace forks twice. 101 * Unlike normal case, with -D *grandparent* process exec's, 102 * becoming a traced process. Child exits (this prevents traced process 103 * from having children it doesn't expect to have), and grandchild 104 * attaches to grandparent similarly to strace -p PID. 105 * This allows for more transparent interaction in cases 106 * when process and its parent are communicating via signals, 107 * wait() etc. Without -D, strace process gets lodged in between, 108 * disrupting parent<->child link. 109 */ 110static bool daemonized_tracer = 0; 111 112#if USE_SEIZE 113static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP; 114# define use_seize (post_attach_sigstop == 0) 115#else 116# define post_attach_sigstop TCB_IGNORE_ONE_SIGSTOP 117# define use_seize 0 118#endif 119 120/* Sometimes we want to print only succeeding syscalls. */ 121bool not_failing_only = 0; 122 123/* Show path associated with fd arguments */ 124bool show_fd_path = 0; 125 126static bool detach_on_execve = 0; 127static bool skip_startup_execve = 0; 128 129static int exit_code = 0; 130static int strace_child = 0; 131static int strace_tracer_pid = 0; 132 133static char *username = NULL; 134static uid_t run_uid; 135static gid_t run_gid; 136 137unsigned int max_strlen = DEFAULT_STRLEN; 138static int acolumn = DEFAULT_ACOLUMN; 139static char *acolumn_spaces; 140 141static char *outfname = NULL; 142/* If -ff, points to stderr. Else, it's our common output log */ 143static FILE *shared_log; 144 145struct tcb *printing_tcp = NULL; 146static struct tcb *current_tcp; 147 148static struct tcb **tcbtab; 149static unsigned int nprocs, tcbtabsize; 150static const char *progname; 151 152unsigned os_release; /* generated from uname()'s u.release */ 153 154static int detach(struct tcb *tcp); 155static int trace(void); 156static void cleanup(void); 157static void interrupt(int sig); 158static sigset_t empty_set, blocked_set; 159 160#ifdef HAVE_SIG_ATOMIC_T 161static volatile sig_atomic_t interrupted; 162#else 163static volatile int interrupted; 164#endif 165 166#ifndef HAVE_STRERROR 167 168#if !HAVE_DECL_SYS_ERRLIST 169extern int sys_nerr; 170extern char *sys_errlist[]; 171#endif 172 173const char * 174strerror(int err_no) 175{ 176 static char buf[sizeof("Unknown error %d") + sizeof(int)*3]; 177 178 if (err_no < 1 || err_no >= sys_nerr) { 179 sprintf(buf, "Unknown error %d", err_no); 180 return buf; 181 } 182 return sys_errlist[err_no]; 183} 184 185#endif /* HAVE_STERRROR */ 186 187static void 188usage(FILE *ofp, int exitval) 189{ 190 fprintf(ofp, "\ 191usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\ 192 [-a column] [-o file] [-s strsize] [-P path]...\n\ 193 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 194 or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\ 195 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 196-c -- count time, calls, and errors for each syscall and report summary\n\ 197-C -- like -c but also print regular output\n\ 198-d -- enable debug output to stderr\n\ 199-D -- run tracer process as a detached grandchild, not as parent\n\ 200-f -- follow forks, -ff -- with output into separate files\n\ 201-i -- print instruction pointer at time of syscall\n\ 202-q -- suppress messages about attaching, detaching, etc.\n\ 203-r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs\n\ 204-T -- print time spent in each syscall\n\ 205-v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\ 206-x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\ 207-y -- print paths associated with file descriptor arguments\n\ 208-h -- print help message, -V -- print version\n\ 209-a column -- alignment COLUMN for printing syscall results (default %d)\n\ 210-b execve -- detach on this syscall\n\ 211-e expr -- a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\ 212 options: trace, abbrev, verbose, raw, signal, read, write\n\ 213-I interruptible --\n\ 214 1: no signals are blocked\n\ 215 2: fatal signals are blocked while decoding syscall (default)\n\ 216 3: fatal signals are always blocked (default if '-o FILE PROG')\n\ 217 4: fatal signals and SIGTSTP (^Z) are always blocked\n\ 218 (useful to make 'strace -o FILE PROG' not stop on ^Z)\n\ 219-o file -- send trace output to FILE instead of stderr\n\ 220-O overhead -- set overhead for tracing syscalls to OVERHEAD usecs\n\ 221-p pid -- trace process with process id PID, may be repeated\n\ 222-s strsize -- limit length of print strings to STRSIZE chars (default %d)\n\ 223-S sortby -- sort syscall counts by: time, calls, name, nothing (default %s)\n\ 224-u username -- run command as username handling setuid and/or setgid\n\ 225-E var=val -- put var=val in the environment for command\n\ 226-E var -- remove var from the environment for command\n\ 227-P path -- trace accesses to path\n\ 228" 229/* ancient, no one should use it 230-F -- attempt to follow vforks (deprecated, use -f)\n\ 231 */ 232/* this is broken, so don't document it 233-z -- print only succeeding syscalls\n\ 234 */ 235, DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY); 236 exit(exitval); 237} 238 239static void die(void) __attribute__ ((noreturn)); 240static void die(void) 241{ 242 if (strace_tracer_pid == getpid()) { 243 cflag = 0; 244 cleanup(); 245 } 246 exit(1); 247} 248 249static void verror_msg(int err_no, const char *fmt, va_list p) 250{ 251 char *msg; 252 253 fflush(NULL); 254 255 /* We want to print entire message with single fprintf to ensure 256 * message integrity if stderr is shared with other programs. 257 * Thus we use vasprintf + single fprintf. 258 */ 259 msg = NULL; 260 if (vasprintf(&msg, fmt, p) >= 0) { 261 if (err_no) 262 fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no)); 263 else 264 fprintf(stderr, "%s: %s\n", progname, msg); 265 free(msg); 266 } else { 267 /* malloc in vasprintf failed, try it without malloc */ 268 fprintf(stderr, "%s: ", progname); 269 vfprintf(stderr, fmt, p); 270 if (err_no) 271 fprintf(stderr, ": %s\n", strerror(err_no)); 272 else 273 putc('\n', stderr); 274 } 275 /* We don't switch stderr to buffered, thus fprintf(stderr) 276 * always flushes its output and this is not necessary: */ 277 /* fflush(stderr); */ 278} 279 280void error_msg(const char *fmt, ...) 281{ 282 va_list p; 283 va_start(p, fmt); 284 verror_msg(0, fmt, p); 285 va_end(p); 286} 287 288void error_msg_and_die(const char *fmt, ...) 289{ 290 va_list p; 291 va_start(p, fmt); 292 verror_msg(0, fmt, p); 293 die(); 294} 295 296void perror_msg(const char *fmt, ...) 297{ 298 va_list p; 299 va_start(p, fmt); 300 verror_msg(errno, fmt, p); 301 va_end(p); 302} 303 304void perror_msg_and_die(const char *fmt, ...) 305{ 306 va_list p; 307 va_start(p, fmt); 308 verror_msg(errno, fmt, p); 309 die(); 310} 311 312void die_out_of_memory(void) 313{ 314 static bool recursed = 0; 315 if (recursed) 316 exit(1); 317 recursed = 1; 318 error_msg_and_die("Out of memory"); 319} 320 321static void 322error_opt_arg(int opt, const char *arg) 323{ 324 error_msg_and_die("Invalid -%c argument: '%s'", opt, arg); 325} 326 327#if USE_SEIZE 328static int 329ptrace_attach_or_seize(int pid) 330{ 331 int r; 332 if (!use_seize) 333 return ptrace(PTRACE_ATTACH, pid, 0, 0); 334 r = ptrace(PTRACE_SEIZE, pid, 0, 0); 335 if (r) 336 return r; 337 r = ptrace(PTRACE_INTERRUPT, pid, 0, 0); 338 return r; 339} 340#else 341# define ptrace_attach_or_seize(pid) ptrace(PTRACE_ATTACH, (pid), 0, 0) 342#endif 343 344/* 345 * Used when we want to unblock stopped traced process. 346 * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL. 347 * Returns 0 on success or if error was ESRCH 348 * (presumably process was killed while we talk to it). 349 * Otherwise prints error message and returns -1. 350 */ 351static int 352ptrace_restart(int op, struct tcb *tcp, int sig) 353{ 354 int err; 355 const char *msg; 356 357 errno = 0; 358 ptrace(op, tcp->pid, (void *) 0, (long) sig); 359 err = errno; 360 if (!err) 361 return 0; 362 363 msg = "SYSCALL"; 364 if (op == PTRACE_CONT) 365 msg = "CONT"; 366 if (op == PTRACE_DETACH) 367 msg = "DETACH"; 368#ifdef PTRACE_LISTEN 369 if (op == PTRACE_LISTEN) 370 msg = "LISTEN"; 371#endif 372 /* 373 * Why curcol != 0? Otherwise sometimes we get this: 374 * 375 * 10252 kill(10253, SIGKILL) = 0 376 * <ptrace(SYSCALL,10252):No such process>10253 ...next decode... 377 * 378 * 10252 died after we retrieved syscall exit data, 379 * but before we tried to restart it. Log looks ugly. 380 */ 381 if (current_tcp && current_tcp->curcol != 0) { 382 tprintf(" <ptrace(%s):%s>\n", msg, strerror(err)); 383 line_ended(); 384 } 385 if (err == ESRCH) 386 return 0; 387 errno = err; 388 perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig); 389 return -1; 390} 391 392static void 393set_cloexec_flag(int fd) 394{ 395 int flags, newflags; 396 397 flags = fcntl(fd, F_GETFD); 398 if (flags < 0) { 399 /* Can happen only if fd is bad. 400 * Should never happen: if it does, we have a bug 401 * in the caller. Therefore we just abort 402 * instead of propagating the error. 403 */ 404 perror_msg_and_die("fcntl(%d, F_GETFD)", fd); 405 } 406 407 newflags = flags | FD_CLOEXEC; 408 if (flags == newflags) 409 return; 410 411 fcntl(fd, F_SETFD, newflags); /* never fails */ 412} 413 414static void kill_save_errno(pid_t pid, int sig) 415{ 416 int saved_errno = errno; 417 418 (void) kill(pid, sig); 419 errno = saved_errno; 420} 421 422/* 423 * When strace is setuid executable, we have to swap uids 424 * before and after filesystem and process management operations. 425 */ 426static void 427swap_uid(void) 428{ 429 int euid = geteuid(), uid = getuid(); 430 431 if (euid != uid && setreuid(euid, uid) < 0) { 432 perror_msg_and_die("setreuid"); 433 } 434} 435 436#if _LFS64_LARGEFILE 437# define fopen_for_output fopen64 438#else 439# define fopen_for_output fopen 440#endif 441 442static FILE * 443strace_fopen(const char *path) 444{ 445 FILE *fp; 446 447 swap_uid(); 448 fp = fopen_for_output(path, "w"); 449 if (!fp) 450 perror_msg_and_die("Can't fopen '%s'", path); 451 swap_uid(); 452 set_cloexec_flag(fileno(fp)); 453 return fp; 454} 455 456static int popen_pid = 0; 457 458#ifndef _PATH_BSHELL 459# define _PATH_BSHELL "/bin/sh" 460#endif 461 462/* 463 * We cannot use standard popen(3) here because we have to distinguish 464 * popen child process from other processes we trace, and standard popen(3) 465 * does not export its child's pid. 466 */ 467static FILE * 468strace_popen(const char *command) 469{ 470 FILE *fp; 471 int fds[2]; 472 473 swap_uid(); 474 if (pipe(fds) < 0) 475 perror_msg_and_die("pipe"); 476 477 set_cloexec_flag(fds[1]); /* never fails */ 478 479 popen_pid = vfork(); 480 if (popen_pid == -1) 481 perror_msg_and_die("vfork"); 482 483 if (popen_pid == 0) { 484 /* child */ 485 close(fds[1]); 486 if (fds[0] != 0) { 487 if (dup2(fds[0], 0)) 488 perror_msg_and_die("dup2"); 489 close(fds[0]); 490 } 491 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 492 perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL); 493 } 494 495 /* parent */ 496 close(fds[0]); 497 swap_uid(); 498 fp = fdopen(fds[1], "w"); 499 if (!fp) 500 die_out_of_memory(); 501 return fp; 502} 503 504void 505tprintf(const char *fmt, ...) 506{ 507 va_list args; 508 509 va_start(args, fmt); 510 if (current_tcp) { 511 int n = strace_vfprintf(current_tcp->outf, fmt, args); 512 if (n < 0) { 513 if (current_tcp->outf != stderr) 514 perror_msg("%s", outfname); 515 } else 516 current_tcp->curcol += n; 517 } 518 va_end(args); 519} 520 521void 522tprints(const char *str) 523{ 524 if (current_tcp) { 525 int n = fputs_unlocked(str, current_tcp->outf); 526 if (n >= 0) { 527 current_tcp->curcol += strlen(str); 528 return; 529 } 530 if (current_tcp->outf != stderr) 531 perror_msg("%s", outfname); 532 } 533} 534 535void 536line_ended(void) 537{ 538 if (current_tcp) { 539 current_tcp->curcol = 0; 540 fflush(current_tcp->outf); 541 } 542 if (printing_tcp) { 543 printing_tcp->curcol = 0; 544 printing_tcp = NULL; 545 } 546} 547 548void 549printleader(struct tcb *tcp) 550{ 551 /* If -ff, "previous tcb we printed" is always the same as current, 552 * because we have per-tcb output files. 553 */ 554 if (followfork >= 2) 555 printing_tcp = tcp; 556 557 if (printing_tcp) { 558 current_tcp = printing_tcp; 559 if (printing_tcp->curcol != 0 && (followfork < 2 || printing_tcp == tcp)) { 560 /* 561 * case 1: we have a shared log (i.e. not -ff), and last line 562 * wasn't finished (same or different tcb, doesn't matter). 563 * case 2: split log, we are the same tcb, but our last line 564 * didn't finish ("SIGKILL nuked us after syscall entry" etc). 565 */ 566 tprints(" <unfinished ...>\n"); 567 printing_tcp->curcol = 0; 568 } 569 } 570 571 printing_tcp = tcp; 572 current_tcp = tcp; 573 current_tcp->curcol = 0; 574 575 if (print_pid_pfx) 576 tprintf("%-5d ", tcp->pid); 577 else if (nprocs > 1 && !outfname) 578 tprintf("[pid %5u] ", tcp->pid); 579 580 if (tflag) { 581 char str[sizeof("HH:MM:SS")]; 582 struct timeval tv, dtv; 583 static struct timeval otv; 584 585 gettimeofday(&tv, NULL); 586 if (rflag) { 587 if (otv.tv_sec == 0) 588 otv = tv; 589 tv_sub(&dtv, &tv, &otv); 590 tprintf("%6ld.%06ld ", 591 (long) dtv.tv_sec, (long) dtv.tv_usec); 592 otv = tv; 593 } 594 else if (tflag > 2) { 595 tprintf("%ld.%06ld ", 596 (long) tv.tv_sec, (long) tv.tv_usec); 597 } 598 else { 599 time_t local = tv.tv_sec; 600 strftime(str, sizeof(str), "%T", localtime(&local)); 601 if (tflag > 1) 602 tprintf("%s.%06ld ", str, (long) tv.tv_usec); 603 else 604 tprintf("%s ", str); 605 } 606 } 607 if (iflag) 608 printcall(tcp); 609} 610 611void 612tabto(void) 613{ 614 if (current_tcp->curcol < acolumn) 615 tprints(acolumn_spaces + current_tcp->curcol); 616} 617 618/* Should be only called directly *after successful attach* to a tracee. 619 * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>" 620 * may create bogus empty FILE.<nonexistant_pid>, and then die. 621 */ 622static void 623newoutf(struct tcb *tcp) 624{ 625 tcp->outf = shared_log; /* if not -ff mode, the same file is for all */ 626 if (followfork >= 2) { 627 char name[520 + sizeof(int) * 3]; 628 sprintf(name, "%.512s.%u", outfname, tcp->pid); 629 tcp->outf = strace_fopen(name); 630 } 631} 632 633static void 634expand_tcbtab(void) 635{ 636 /* Allocate some more TCBs and expand the table. 637 We don't want to relocate the TCBs because our 638 callers have pointers and it would be a pain. 639 So tcbtab is a table of pointers. Since we never 640 free the TCBs, we allocate a single chunk of many. */ 641 int i = tcbtabsize; 642 struct tcb *newtcbs = calloc(tcbtabsize, sizeof(newtcbs[0])); 643 struct tcb **newtab = realloc(tcbtab, tcbtabsize * 2 * sizeof(tcbtab[0])); 644 if (!newtab || !newtcbs) 645 die_out_of_memory(); 646 tcbtabsize *= 2; 647 tcbtab = newtab; 648 while (i < tcbtabsize) 649 tcbtab[i++] = newtcbs++; 650} 651 652static struct tcb * 653alloctcb(int pid) 654{ 655 int i; 656 struct tcb *tcp; 657 658 if (nprocs == tcbtabsize) 659 expand_tcbtab(); 660 661 for (i = 0; i < tcbtabsize; i++) { 662 tcp = tcbtab[i]; 663 if ((tcp->flags & TCB_INUSE) == 0) { 664 memset(tcp, 0, sizeof(*tcp)); 665 tcp->pid = pid; 666 tcp->flags = TCB_INUSE; 667#if SUPPORTED_PERSONALITIES > 1 668 tcp->currpers = current_personality; 669#endif 670 nprocs++; 671 if (debug_flag) 672 fprintf(stderr, "new tcb for pid %d, active tcbs:%d\n", tcp->pid, nprocs); 673 return tcp; 674 } 675 } 676 error_msg_and_die("bug in alloctcb"); 677} 678 679static void 680droptcb(struct tcb *tcp) 681{ 682 if (tcp->pid == 0) 683 return; 684 685 nprocs--; 686 if (debug_flag) 687 fprintf(stderr, "dropped tcb for pid %d, %d remain\n", tcp->pid, nprocs); 688 689 if (tcp->outf) { 690 if (followfork >= 2) { 691 if (tcp->curcol != 0) 692 fprintf(tcp->outf, " <detached ...>\n"); 693 fclose(tcp->outf); 694 } else { 695 if (printing_tcp == tcp && tcp->curcol != 0) 696 fprintf(tcp->outf, " <detached ...>\n"); 697 fflush(tcp->outf); 698 } 699 } 700 701 if (current_tcp == tcp) 702 current_tcp = NULL; 703 if (printing_tcp == tcp) 704 printing_tcp = NULL; 705 706 memset(tcp, 0, sizeof(*tcp)); 707} 708 709/* detach traced process; continue with sig 710 * Never call DETACH twice on the same process as both unattached and 711 * attached-unstopped processes give the same ESRCH. For unattached process we 712 * would SIGSTOP it and wait for its SIGSTOP notification forever. 713 */ 714static int 715detach(struct tcb *tcp) 716{ 717 int error; 718 int status, sigstop_expected; 719 720 if (tcp->flags & TCB_BPTSET) 721 clearbpt(tcp); 722 723 /* 724 * Linux wrongly insists the child be stopped 725 * before detaching. Arghh. We go through hoops 726 * to make a clean break of things. 727 */ 728#if defined(SPARC) 729# undef PTRACE_DETACH 730# define PTRACE_DETACH PTRACE_SUNDETACH 731#endif 732 733 error = 0; 734 sigstop_expected = 0; 735 if (tcp->flags & TCB_ATTACHED) { 736 /* 737 * We attached but possibly didn't see the expected SIGSTOP. 738 * We must catch exactly one as otherwise the detached process 739 * would be left stopped (process state T). 740 */ 741 sigstop_expected = (tcp->flags & TCB_IGNORE_ONE_SIGSTOP); 742 error = ptrace(PTRACE_DETACH, tcp->pid, (char *) 1, 0); 743 if (error == 0) { 744 /* On a clear day, you can see forever. */ 745 } 746 else if (errno != ESRCH) { 747 /* Shouldn't happen. */ 748 perror_msg("detach: ptrace(PTRACE_DETACH, ...)"); 749 } 750 else if (my_tkill(tcp->pid, 0) < 0) { 751 if (errno != ESRCH) 752 perror_msg("detach: checking sanity"); 753 } 754 else if (!sigstop_expected && my_tkill(tcp->pid, SIGSTOP) < 0) { 755 if (errno != ESRCH) 756 perror_msg("detach: stopping child"); 757 } 758 else 759 sigstop_expected = 1; 760 } 761 762 if (sigstop_expected) { 763 for (;;) { 764#ifdef __WALL 765 if (waitpid(tcp->pid, &status, __WALL) < 0) { 766 if (errno == ECHILD) /* Already gone. */ 767 break; 768 if (errno != EINVAL) { 769 perror_msg("detach: waiting"); 770 break; 771 } 772#endif /* __WALL */ 773 /* No __WALL here. */ 774 if (waitpid(tcp->pid, &status, 0) < 0) { 775 if (errno != ECHILD) { 776 perror_msg("detach: waiting"); 777 break; 778 } 779#ifdef __WCLONE 780 /* If no processes, try clones. */ 781 if (waitpid(tcp->pid, &status, __WCLONE) < 0) { 782 if (errno != ECHILD) 783 perror_msg("detach: waiting"); 784 break; 785 } 786#endif /* __WCLONE */ 787 } 788#ifdef __WALL 789 } 790#endif 791 if (!WIFSTOPPED(status)) { 792 /* Au revoir, mon ami. */ 793 break; 794 } 795 if (WSTOPSIG(status) == SIGSTOP) { 796 ptrace_restart(PTRACE_DETACH, tcp, 0); 797 break; 798 } 799 error = ptrace_restart(PTRACE_CONT, tcp, 800 WSTOPSIG(status) == syscall_trap_sig ? 0 801 : WSTOPSIG(status)); 802 if (error < 0) 803 break; 804 } 805 } 806 807 if (!qflag && (tcp->flags & TCB_ATTACHED)) 808 fprintf(stderr, "Process %u detached\n", tcp->pid); 809 810 droptcb(tcp); 811 812 return error; 813} 814 815static void 816process_opt_p_list(char *opt) 817{ 818 while (*opt) { 819 /* 820 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`". 821 * pidof uses space as delim, pgrep uses newline. :( 822 */ 823 int pid; 824 char *delim = opt + strcspn(opt, ", \n\t"); 825 char c = *delim; 826 827 *delim = '\0'; 828 pid = string_to_uint(opt); 829 if (pid <= 0) { 830 error_msg_and_die("Invalid process id: '%s'", opt); 831 } 832 if (pid == strace_tracer_pid) { 833 error_msg_and_die("I'm sorry, I can't let you do that, Dave."); 834 } 835 *delim = c; 836 alloctcb(pid); 837 if (c == '\0') 838 break; 839 opt = delim + 1; 840 } 841} 842 843static void 844startup_attach(void) 845{ 846 int tcbi; 847 struct tcb *tcp; 848 849 /* 850 * Block user interruptions as we would leave the traced 851 * process stopped (process state T) if we would terminate in 852 * between PTRACE_ATTACH and wait4() on SIGSTOP. 853 * We rely on cleanup() from this point on. 854 */ 855 if (interactive) 856 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 857 858 if (daemonized_tracer) { 859 pid_t pid = fork(); 860 if (pid < 0) { 861 perror_msg_and_die("fork"); 862 } 863 if (pid) { /* parent */ 864 /* 865 * Wait for grandchild to attach to straced process 866 * (grandparent). Grandchild SIGKILLs us after it attached. 867 * Grandparent's wait() is unblocked by our death, 868 * it proceeds to exec the straced program. 869 */ 870 pause(); 871 _exit(0); /* paranoia */ 872 } 873 /* grandchild */ 874 /* We will be the tracer process. Remember our new pid: */ 875 strace_tracer_pid = getpid(); 876 } 877 878 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) { 879 tcp = tcbtab[tcbi]; 880 881 if (!(tcp->flags & TCB_INUSE)) 882 continue; 883 884 /* Is this a process we should attach to, but not yet attached? */ 885 if (tcp->flags & TCB_ATTACHED) 886 continue; /* no, we already attached it */ 887 888 if (followfork && !daemonized_tracer) { 889 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3]; 890 DIR *dir; 891 892 sprintf(procdir, "/proc/%d/task", tcp->pid); 893 dir = opendir(procdir); 894 if (dir != NULL) { 895 unsigned int ntid = 0, nerr = 0; 896 struct dirent *de; 897 898 while ((de = readdir(dir)) != NULL) { 899 struct tcb *cur_tcp; 900 int tid; 901 902 if (de->d_fileno == 0) 903 continue; 904 /* we trust /proc filesystem */ 905 tid = atoi(de->d_name); 906 if (tid <= 0) 907 continue; 908 ++ntid; 909 if (ptrace_attach_or_seize(tid) < 0) { 910 ++nerr; 911 if (debug_flag) 912 fprintf(stderr, "attach to pid %d failed\n", tid); 913 continue; 914 } 915 if (debug_flag) 916 fprintf(stderr, "attach to pid %d succeeded\n", tid); 917 cur_tcp = tcp; 918 if (tid != tcp->pid) 919 cur_tcp = alloctcb(tid); 920 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 921 newoutf(cur_tcp); 922 } 923 closedir(dir); 924 if (interactive) { 925 sigprocmask(SIG_SETMASK, &empty_set, NULL); 926 if (interrupted) 927 goto ret; 928 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 929 } 930 ntid -= nerr; 931 if (ntid == 0) { 932 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 933 droptcb(tcp); 934 continue; 935 } 936 if (!qflag) { 937 fprintf(stderr, ntid > 1 938? "Process %u attached with %u threads\n" 939: "Process %u attached\n", 940 tcp->pid, ntid); 941 } 942 if (!(tcp->flags & TCB_ATTACHED)) { 943 /* -p PID, we failed to attach to PID itself 944 * but did attach to some of its sibling threads. 945 * Drop PID's tcp. 946 */ 947 droptcb(tcp); 948 } 949 continue; 950 } /* if (opendir worked) */ 951 } /* if (-f) */ 952 if (ptrace_attach_or_seize(tcp->pid) < 0) { 953 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 954 droptcb(tcp); 955 continue; 956 } 957 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 958 newoutf(tcp); 959 if (debug_flag) 960 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid); 961 962 if (daemonized_tracer) { 963 /* 964 * Make parent go away. 965 * Also makes grandparent's wait() unblock. 966 */ 967 kill(getppid(), SIGKILL); 968 } 969 970 if (!qflag) 971 fprintf(stderr, 972 "Process %u attached\n", 973 tcp->pid); 974 } /* for each tcbtab[] */ 975 976 ret: 977 if (interactive) 978 sigprocmask(SIG_SETMASK, &empty_set, NULL); 979} 980 981/* Stack-o-phobic exec helper, in the hope to work around 982 * NOMMU + "daemonized tracer" difficulty. 983 */ 984struct exec_params { 985 int fd_to_close; 986 uid_t run_euid; 987 gid_t run_egid; 988 char **argv; 989 char *pathname; 990}; 991static struct exec_params params_for_tracee; 992static void __attribute__ ((noinline, noreturn)) 993exec_or_die(void) 994{ 995 struct exec_params *params = ¶ms_for_tracee; 996 997 if (params->fd_to_close >= 0) 998 close(params->fd_to_close); 999 if (!daemonized_tracer && !use_seize) { 1000 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) { 1001 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)"); 1002 } 1003 } 1004 1005 if (username != NULL) { 1006 /* 1007 * It is important to set groups before we 1008 * lose privileges on setuid. 1009 */ 1010 if (initgroups(username, run_gid) < 0) { 1011 perror_msg_and_die("initgroups"); 1012 } 1013 if (setregid(run_gid, params->run_egid) < 0) { 1014 perror_msg_and_die("setregid"); 1015 } 1016 if (setreuid(run_uid, params->run_euid) < 0) { 1017 perror_msg_and_die("setreuid"); 1018 } 1019 } 1020 else if (geteuid() != 0) 1021 if (setreuid(run_uid, run_uid) < 0) { 1022 perror_msg_and_die("setreuid"); 1023 } 1024 1025 if (!daemonized_tracer) { 1026 /* 1027 * Induce a ptrace stop. Tracer (our parent) 1028 * will resume us with PTRACE_SYSCALL and display 1029 * the immediately following execve syscall. 1030 * Can't do this on NOMMU systems, we are after 1031 * vfork: parent is blocked, stopping would deadlock. 1032 */ 1033 if (!NOMMU_SYSTEM) 1034 kill(getpid(), SIGSTOP); 1035 } else { 1036 alarm(3); 1037 /* we depend on SIGCHLD set to SIG_DFL by init code */ 1038 /* if it happens to be SIG_IGN'ed, wait won't block */ 1039 wait(NULL); 1040 alarm(0); 1041 } 1042 1043 execv(params->pathname, params->argv); 1044 perror_msg_and_die("exec"); 1045} 1046 1047static void 1048startup_child(char **argv) 1049{ 1050 struct stat statbuf; 1051 const char *filename; 1052 char pathname[MAXPATHLEN]; 1053 int pid; 1054 struct tcb *tcp; 1055 1056 filename = argv[0]; 1057 if (strchr(filename, '/')) { 1058 if (strlen(filename) > sizeof pathname - 1) { 1059 errno = ENAMETOOLONG; 1060 perror_msg_and_die("exec"); 1061 } 1062 strcpy(pathname, filename); 1063 } 1064#ifdef USE_DEBUGGING_EXEC 1065 /* 1066 * Debuggers customarily check the current directory 1067 * first regardless of the path but doing that gives 1068 * security geeks a panic attack. 1069 */ 1070 else if (stat(filename, &statbuf) == 0) 1071 strcpy(pathname, filename); 1072#endif /* USE_DEBUGGING_EXEC */ 1073 else { 1074 const char *path; 1075 int m, n, len; 1076 1077 for (path = getenv("PATH"); path && *path; path += m) { 1078 const char *colon = strchr(path, ':'); 1079 if (colon) { 1080 n = colon - path; 1081 m = n + 1; 1082 } 1083 else 1084 m = n = strlen(path); 1085 if (n == 0) { 1086 if (!getcwd(pathname, MAXPATHLEN)) 1087 continue; 1088 len = strlen(pathname); 1089 } 1090 else if (n > sizeof pathname - 1) 1091 continue; 1092 else { 1093 strncpy(pathname, path, n); 1094 len = n; 1095 } 1096 if (len && pathname[len - 1] != '/') 1097 pathname[len++] = '/'; 1098 strcpy(pathname + len, filename); 1099 if (stat(pathname, &statbuf) == 0 && 1100 /* Accept only regular files 1101 with some execute bits set. 1102 XXX not perfect, might still fail */ 1103 S_ISREG(statbuf.st_mode) && 1104 (statbuf.st_mode & 0111)) 1105 break; 1106 } 1107 } 1108 if (stat(pathname, &statbuf) < 0) { 1109 perror_msg_and_die("Can't stat '%s'", filename); 1110 } 1111 1112 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1; 1113 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid; 1114 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid; 1115 params_for_tracee.argv = argv; 1116 /* 1117 * On NOMMU, can be safely freed only after execve in tracee. 1118 * It's hard to know when that happens, so we just leak it. 1119 */ 1120 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname; 1121 1122 strace_child = pid = fork(); 1123 if (pid < 0) { 1124 perror_msg_and_die("fork"); 1125 } 1126 if ((pid != 0 && daemonized_tracer) 1127 || (pid == 0 && !daemonized_tracer) 1128 ) { 1129 /* We are to become the tracee. Two cases: 1130 * -D: we are parent 1131 * not -D: we are child 1132 */ 1133 exec_or_die(); 1134 } 1135 1136 /* We are the tracer */ 1137 1138 if (!daemonized_tracer) { 1139 if (!use_seize) { 1140 /* child did PTRACE_TRACEME, nothing to do in parent */ 1141 } else { 1142 if (!NOMMU_SYSTEM) { 1143 /* Wait until child stopped itself */ 1144 int status; 1145 while (waitpid(pid, &status, WSTOPPED) < 0) { 1146 if (errno == EINTR) 1147 continue; 1148 perror_msg_and_die("waitpid"); 1149 } 1150 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) { 1151 kill_save_errno(pid, SIGKILL); 1152 perror_msg_and_die("Unexpected wait status %x", status); 1153 } 1154 skip_startup_execve = 1; 1155 } 1156 /* Else: NOMMU case, we have no way to sync. 1157 * Just attach to it as soon as possible. 1158 * This means that we may miss a few first syscalls... 1159 */ 1160 1161 if (ptrace_attach_or_seize(pid)) { 1162 kill_save_errno(pid, SIGKILL); 1163 perror_msg_and_die("Can't attach to %d", pid); 1164 } 1165 if (!NOMMU_SYSTEM) 1166 kill(pid, SIGCONT); 1167 } 1168 tcp = alloctcb(pid); 1169 if (!NOMMU_SYSTEM) 1170 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP | post_attach_sigstop; 1171 else 1172 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP; 1173 newoutf(tcp); 1174 } 1175 else { 1176 /* With -D, we are *child* here, IOW: different pid. Fetch it: */ 1177 strace_tracer_pid = getpid(); 1178 /* The tracee is our parent: */ 1179 pid = getppid(); 1180 alloctcb(pid); 1181 /* attaching will be done later, by startup_attach */ 1182 /* note: we don't do newoutf(tcp) here either! */ 1183 skip_startup_execve = 1; 1184 1185 /* NOMMU BUG! -D mode is active, we (child) return, 1186 * and we will scribble over parent's stack! 1187 * When parent later unpauses, it segfaults. 1188 * 1189 * We work around it 1190 * (1) by declaring exec_or_die() NORETURN, 1191 * hopefully compiler will just jump to it 1192 * instead of call (won't push anything to stack), 1193 * (2) by trying very hard in exec_or_die() 1194 * to not use any stack, 1195 * (3) having a really big (MAXPATHLEN) stack object 1196 * in this function, which creates a "buffer" between 1197 * child's and parent's stack pointers. 1198 * This may save us if (1) and (2) failed 1199 * and compiler decided to use stack in exec_or_die() anyway 1200 * (happens on i386 because of stack parameter passing). 1201 * 1202 * A cleaner solution is to use makecontext + setcontext 1203 * to create a genuine separate stack and execute on it. 1204 */ 1205 } 1206} 1207 1208/* 1209 * Test whether the kernel support PTRACE_O_TRACECLONE et al options. 1210 * First fork a new child, call ptrace with PTRACE_SETOPTIONS on it, 1211 * and then see which options are supported by the kernel. 1212 */ 1213static int 1214test_ptrace_setoptions_followfork(void) 1215{ 1216 int pid, expected_grandchild = 0, found_grandchild = 0; 1217 const unsigned int test_options = PTRACE_O_TRACECLONE | 1218 PTRACE_O_TRACEFORK | 1219 PTRACE_O_TRACEVFORK; 1220 1221 /* Need fork for test. NOMMU has no forks */ 1222 if (NOMMU_SYSTEM) 1223 goto worked; /* be bold, and pretend that test succeeded */ 1224 1225 pid = fork(); 1226 if (pid < 0) 1227 perror_msg_and_die("fork"); 1228 if (pid == 0) { 1229 pid = getpid(); 1230 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1231 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1232 __func__); 1233 kill_save_errno(pid, SIGSTOP); 1234 if (fork() < 0) 1235 perror_msg_and_die("fork"); 1236 _exit(0); 1237 } 1238 1239 while (1) { 1240 int status, tracee_pid; 1241 1242 errno = 0; 1243 tracee_pid = wait(&status); 1244 if (tracee_pid <= 0) { 1245 if (errno == EINTR) 1246 continue; 1247 if (errno == ECHILD) 1248 break; 1249 kill_save_errno(pid, SIGKILL); 1250 perror_msg_and_die("%s: unexpected wait result %d", 1251 __func__, tracee_pid); 1252 } 1253 if (WIFEXITED(status)) { 1254 if (WEXITSTATUS(status)) { 1255 if (tracee_pid != pid) 1256 kill_save_errno(pid, SIGKILL); 1257 error_msg_and_die("%s: unexpected exit status %u", 1258 __func__, WEXITSTATUS(status)); 1259 } 1260 continue; 1261 } 1262 if (WIFSIGNALED(status)) { 1263 if (tracee_pid != pid) 1264 kill_save_errno(pid, SIGKILL); 1265 error_msg_and_die("%s: unexpected signal %u", 1266 __func__, WTERMSIG(status)); 1267 } 1268 if (!WIFSTOPPED(status)) { 1269 if (tracee_pid != pid) 1270 kill_save_errno(tracee_pid, SIGKILL); 1271 kill_save_errno(pid, SIGKILL); 1272 error_msg_and_die("%s: unexpected wait status %x", 1273 __func__, status); 1274 } 1275 if (tracee_pid != pid) { 1276 found_grandchild = tracee_pid; 1277 if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0) { 1278 kill_save_errno(tracee_pid, SIGKILL); 1279 kill_save_errno(pid, SIGKILL); 1280 perror_msg_and_die("PTRACE_CONT doesn't work"); 1281 } 1282 continue; 1283 } 1284 switch (WSTOPSIG(status)) { 1285 case SIGSTOP: 1286 if (ptrace(PTRACE_SETOPTIONS, pid, 0, test_options) < 0 1287 && errno != EINVAL && errno != EIO) 1288 perror_msg("PTRACE_SETOPTIONS"); 1289 break; 1290 case SIGTRAP: 1291 if (status >> 16 == PTRACE_EVENT_FORK) { 1292 long msg = 0; 1293 1294 if (ptrace(PTRACE_GETEVENTMSG, pid, 1295 NULL, (long) &msg) == 0) 1296 expected_grandchild = msg; 1297 } 1298 break; 1299 } 1300 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) { 1301 kill_save_errno(pid, SIGKILL); 1302 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1303 } 1304 } 1305 if (expected_grandchild && expected_grandchild == found_grandchild) { 1306 worked: 1307 ptrace_setoptions |= test_options; 1308 if (debug_flag) 1309 fprintf(stderr, "ptrace_setoptions = %#x\n", 1310 ptrace_setoptions); 1311 return 0; 1312 } 1313 error_msg("Test for PTRACE_O_TRACECLONE failed, " 1314 "giving up using this feature."); 1315 return 1; 1316} 1317 1318/* 1319 * Test whether the kernel support PTRACE_O_TRACESYSGOOD. 1320 * First fork a new child, call ptrace(PTRACE_SETOPTIONS) on it, 1321 * and then see whether it will stop with (SIGTRAP | 0x80). 1322 * 1323 * Use of this option enables correct handling of user-generated SIGTRAPs, 1324 * and SIGTRAPs generated by special instructions such as int3 on x86: 1325 * _start: .globl _start 1326 * int3 1327 * movl $42, %ebx 1328 * movl $1, %eax 1329 * int $0x80 1330 * (compile with: "gcc -nostartfiles -nostdlib -o int3 int3.S") 1331 */ 1332static int 1333test_ptrace_setoptions_for_all(void) 1334{ 1335 const unsigned int test_options = PTRACE_O_TRACESYSGOOD | 1336 PTRACE_O_TRACEEXEC; 1337 int pid; 1338 int it_worked = 0; 1339 1340 /* Need fork for test. NOMMU has no forks */ 1341 if (NOMMU_SYSTEM) 1342 goto worked; /* be bold, and pretend that test succeeded */ 1343 1344 pid = fork(); 1345 if (pid < 0) 1346 perror_msg_and_die("fork"); 1347 1348 if (pid == 0) { 1349 pid = getpid(); 1350 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1351 /* Note: exits with exitcode 1 */ 1352 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1353 __func__); 1354 kill(pid, SIGSTOP); 1355 _exit(0); /* parent should see entry into this syscall */ 1356 } 1357 1358 while (1) { 1359 int status, tracee_pid; 1360 1361 errno = 0; 1362 tracee_pid = wait(&status); 1363 if (tracee_pid <= 0) { 1364 if (errno == EINTR) 1365 continue; 1366 kill_save_errno(pid, SIGKILL); 1367 perror_msg_and_die("%s: unexpected wait result %d", 1368 __func__, tracee_pid); 1369 } 1370 if (WIFEXITED(status)) { 1371 if (WEXITSTATUS(status) == 0) 1372 break; 1373 error_msg_and_die("%s: unexpected exit status %u", 1374 __func__, WEXITSTATUS(status)); 1375 } 1376 if (WIFSIGNALED(status)) { 1377 error_msg_and_die("%s: unexpected signal %u", 1378 __func__, WTERMSIG(status)); 1379 } 1380 if (!WIFSTOPPED(status)) { 1381 kill(pid, SIGKILL); 1382 error_msg_and_die("%s: unexpected wait status %x", 1383 __func__, status); 1384 } 1385 if (WSTOPSIG(status) == SIGSTOP) { 1386 /* 1387 * We don't check "options aren't accepted" error. 1388 * If it happens, we'll never get (SIGTRAP | 0x80), 1389 * and thus will decide to not use the option. 1390 * IOW: the outcome of the test will be correct. 1391 */ 1392 if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0 1393 && errno != EINVAL && errno != EIO) 1394 perror_msg("PTRACE_SETOPTIONS"); 1395 } 1396 if (WSTOPSIG(status) == (SIGTRAP | 0x80)) { 1397 it_worked = 1; 1398 } 1399 if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) { 1400 kill_save_errno(pid, SIGKILL); 1401 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1402 } 1403 } 1404 1405 if (it_worked) { 1406 worked: 1407 syscall_trap_sig = (SIGTRAP | 0x80); 1408 ptrace_setoptions |= test_options; 1409 if (debug_flag) 1410 fprintf(stderr, "ptrace_setoptions = %#x\n", 1411 ptrace_setoptions); 1412 return 0; 1413 } 1414 1415 error_msg("Test for PTRACE_O_TRACESYSGOOD failed, " 1416 "giving up using this feature."); 1417 return 1; 1418} 1419 1420#if USE_SEIZE 1421static void 1422test_ptrace_seize(void) 1423{ 1424 int pid; 1425 1426 /* Need fork for test. NOMMU has no forks */ 1427 if (NOMMU_SYSTEM) { 1428 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1429 return; 1430 } 1431 1432 pid = fork(); 1433 if (pid < 0) 1434 perror_msg_and_die("fork"); 1435 1436 if (pid == 0) { 1437 pause(); 1438 _exit(0); 1439 } 1440 1441 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After 1442 * attaching tracee continues to run unless a trap condition occurs. 1443 * PTRACE_SEIZE doesn't affect signal or group stop state. 1444 */ 1445 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) { 1446 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1447 } else if (debug_flag) { 1448 fprintf(stderr, "PTRACE_SEIZE doesn't work\n"); 1449 } 1450 1451 kill(pid, SIGKILL); 1452 1453 while (1) { 1454 int status, tracee_pid; 1455 1456 errno = 0; 1457 tracee_pid = waitpid(pid, &status, 0); 1458 if (tracee_pid <= 0) { 1459 if (errno == EINTR) 1460 continue; 1461 perror_msg_and_die("%s: unexpected wait result %d", 1462 __func__, tracee_pid); 1463 } 1464 if (WIFSIGNALED(status)) { 1465 return; 1466 } 1467 error_msg_and_die("%s: unexpected wait status %x", 1468 __func__, status); 1469 } 1470} 1471#else /* !USE_SEIZE */ 1472# define test_ptrace_seize() ((void)0) 1473#endif 1474 1475static unsigned 1476get_os_release(void) 1477{ 1478 unsigned rel; 1479 const char *p; 1480 struct utsname u; 1481 if (uname(&u) < 0) 1482 perror_msg_and_die("uname"); 1483 /* u.release has this form: "3.2.9[-some-garbage]" */ 1484 rel = 0; 1485 p = u.release; 1486 for (;;) { 1487 if (!(*p >= '0' && *p <= '9')) 1488 error_msg_and_die("Bad OS release string: '%s'", u.release); 1489 /* Note: this open-codes KERNEL_VERSION(): */ 1490 rel = (rel << 8) | atoi(p); 1491 if (rel >= KERNEL_VERSION(1,0,0)) 1492 break; 1493 while (*p >= '0' && *p <= '9') 1494 p++; 1495 if (*p != '.') { 1496 if (rel >= KERNEL_VERSION(0,1,0)) { 1497 /* "X.Y-something" means "X.Y.0" */ 1498 rel <<= 8; 1499 break; 1500 } 1501 error_msg_and_die("Bad OS release string: '%s'", u.release); 1502 } 1503 p++; 1504 } 1505 return rel; 1506} 1507 1508/* 1509 * Initialization part of main() was eating much stack (~0.5k), 1510 * which was unused after init. 1511 * We can reuse it if we move init code into a separate function. 1512 * 1513 * Don't want main() to inline us and defeat the reason 1514 * we have a separate function. 1515 */ 1516static void __attribute__ ((noinline)) 1517init(int argc, char *argv[]) 1518{ 1519 struct tcb *tcp; 1520 int c, i; 1521 int optF = 0; 1522 struct sigaction sa; 1523 1524 progname = argv[0] ? argv[0] : "strace"; 1525 1526 /* Make sure SIGCHLD has the default action so that waitpid 1527 definitely works without losing track of children. The user 1528 should not have given us a bogus state to inherit, but he might 1529 have. Arguably we should detect SIG_IGN here and pass it on 1530 to children, but probably noone really needs that. */ 1531 signal(SIGCHLD, SIG_DFL); 1532 1533 strace_tracer_pid = getpid(); 1534 1535 os_release = get_os_release(); 1536 1537 /* Allocate the initial tcbtab. */ 1538 tcbtabsize = argc; /* Surely enough for all -p args. */ 1539 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0])); 1540 if (!tcbtab) 1541 die_out_of_memory(); 1542 tcp = calloc(tcbtabsize, sizeof(*tcp)); 1543 if (!tcp) 1544 die_out_of_memory(); 1545 for (c = 0; c < tcbtabsize; c++) 1546 tcbtab[c] = tcp++; 1547 1548 shared_log = stderr; 1549 set_sortby(DEFAULT_SORTBY); 1550 set_personality(DEFAULT_PERSONALITY); 1551 qualify("trace=all"); 1552 qualify("abbrev=all"); 1553 qualify("verbose=all"); 1554#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE) 1555# error Bug in DEFAULT_QUAL_FLAGS 1556#endif 1557 qualify("signal=all"); 1558 while ((c = getopt(argc, argv, 1559 "+b:cCdfFhiqrtTvVxyz" 1560 "D" 1561 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) { 1562 switch (c) { 1563 case 'b': 1564 if (strcmp(optarg, "execve") != 0) 1565 error_msg_and_die("Syscall '%s' for -b isn't supported", 1566 optarg); 1567 detach_on_execve = 1; 1568 break; 1569 case 'c': 1570 if (cflag == CFLAG_BOTH) { 1571 error_msg_and_die("-c and -C are mutually exclusive"); 1572 } 1573 cflag = CFLAG_ONLY_STATS; 1574 break; 1575 case 'C': 1576 if (cflag == CFLAG_ONLY_STATS) { 1577 error_msg_and_die("-c and -C are mutually exclusive"); 1578 } 1579 cflag = CFLAG_BOTH; 1580 break; 1581 case 'd': 1582 debug_flag = 1; 1583 break; 1584 case 'D': 1585 daemonized_tracer = 1; 1586 break; 1587 case 'F': 1588 optF = 1; 1589 break; 1590 case 'f': 1591 followfork++; 1592 break; 1593 case 'h': 1594 usage(stdout, 0); 1595 break; 1596 case 'i': 1597 iflag = 1; 1598 break; 1599 case 'q': 1600 qflag = 1; 1601 break; 1602 case 'r': 1603 rflag = 1; 1604 /* fall through to tflag++ */ 1605 case 't': 1606 tflag++; 1607 break; 1608 case 'T': 1609 Tflag = 1; 1610 break; 1611 case 'x': 1612 xflag++; 1613 break; 1614 case 'y': 1615 show_fd_path = 1; 1616 break; 1617 case 'v': 1618 qualify("abbrev=none"); 1619 break; 1620 case 'V': 1621 printf("%s -- version %s\n", PACKAGE_NAME, VERSION); 1622 exit(0); 1623 break; 1624 case 'z': 1625 not_failing_only = 1; 1626 break; 1627 case 'a': 1628 acolumn = string_to_uint(optarg); 1629 if (acolumn < 0) 1630 error_opt_arg(c, optarg); 1631 break; 1632 case 'e': 1633 qualify(optarg); 1634 break; 1635 case 'o': 1636 outfname = strdup(optarg); 1637 break; 1638 case 'O': 1639 i = string_to_uint(optarg); 1640 if (i < 0) 1641 error_opt_arg(c, optarg); 1642 set_overhead(i); 1643 break; 1644 case 'p': 1645 process_opt_p_list(optarg); 1646 break; 1647 case 'P': 1648 pathtrace_select(optarg); 1649 break; 1650 case 's': 1651 i = string_to_uint(optarg); 1652 if (i < 0) 1653 error_opt_arg(c, optarg); 1654 max_strlen = i; 1655 break; 1656 case 'S': 1657 set_sortby(optarg); 1658 break; 1659 case 'u': 1660 username = strdup(optarg); 1661 break; 1662 case 'E': 1663 if (putenv(optarg) < 0) 1664 die_out_of_memory(); 1665 break; 1666 case 'I': 1667 opt_intr = string_to_uint(optarg); 1668 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS) 1669 error_opt_arg(c, optarg); 1670 break; 1671 default: 1672 usage(stderr, 1); 1673 break; 1674 } 1675 } 1676 argv += optind; 1677 /* argc -= optind; - no need, argc is not used below */ 1678 1679 acolumn_spaces = malloc(acolumn + 1); 1680 if (!acolumn_spaces) 1681 die_out_of_memory(); 1682 memset(acolumn_spaces, ' ', acolumn); 1683 acolumn_spaces[acolumn] = '\0'; 1684 1685 /* Must have PROG [ARGS], or -p PID. Not both. */ 1686 if (!argv[0] == !nprocs) 1687 usage(stderr, 1); 1688 1689 if (nprocs != 0 && daemonized_tracer) { 1690 error_msg_and_die("-D and -p are mutually exclusive"); 1691 } 1692 1693 if (!followfork) 1694 followfork = optF; 1695 1696 if (followfork >= 2 && cflag) { 1697 error_msg_and_die("(-c or -C) and -ff are mutually exclusive"); 1698 } 1699 1700 /* See if they want to run as another user. */ 1701 if (username != NULL) { 1702 struct passwd *pent; 1703 1704 if (getuid() != 0 || geteuid() != 0) { 1705 error_msg_and_die("You must be root to use the -u option"); 1706 } 1707 pent = getpwnam(username); 1708 if (pent == NULL) { 1709 error_msg_and_die("Cannot find user '%s'", username); 1710 } 1711 run_uid = pent->pw_uid; 1712 run_gid = pent->pw_gid; 1713 } 1714 else { 1715 run_uid = getuid(); 1716 run_gid = getgid(); 1717 } 1718 1719 /* 1720 * On any reasonably recent Linux kernel (circa about 2.5.46) 1721 * need_fork_exec_workarounds should stay 0 after these tests: 1722 */ 1723 /*need_fork_exec_workarounds = 0; - already is */ 1724 if (followfork) 1725 need_fork_exec_workarounds = test_ptrace_setoptions_followfork(); 1726 need_fork_exec_workarounds |= test_ptrace_setoptions_for_all(); 1727 test_ptrace_seize(); 1728 1729 /* Check if they want to redirect the output. */ 1730 if (outfname) { 1731 /* See if they want to pipe the output. */ 1732 if (outfname[0] == '|' || outfname[0] == '!') { 1733 /* 1734 * We can't do the <outfname>.PID funny business 1735 * when using popen, so prohibit it. 1736 */ 1737 if (followfork >= 2) 1738 error_msg_and_die("Piping the output and -ff are mutually exclusive"); 1739 shared_log = strace_popen(outfname + 1); 1740 } 1741 else if (followfork < 2) 1742 shared_log = strace_fopen(outfname); 1743 } else { 1744 /* -ff without -o FILE is the same as single -f */ 1745 if (followfork >= 2) 1746 followfork = 1; 1747 } 1748 1749 if (!outfname || outfname[0] == '|' || outfname[0] == '!') { 1750 char *buf = malloc(BUFSIZ); 1751 if (!buf) 1752 die_out_of_memory(); 1753 setvbuf(shared_log, buf, _IOLBF, BUFSIZ); 1754 } 1755 if (outfname && argv[0]) { 1756 if (!opt_intr) 1757 opt_intr = INTR_NEVER; 1758 qflag = 1; 1759 } 1760 if (!opt_intr) 1761 opt_intr = INTR_WHILE_WAIT; 1762 1763 /* argv[0] -pPID -oFILE Default interactive setting 1764 * yes 0 0 INTR_WHILE_WAIT 1765 * no 1 0 INTR_WHILE_WAIT 1766 * yes 0 1 INTR_NEVER 1767 * no 1 1 INTR_WHILE_WAIT 1768 */ 1769 1770 sigemptyset(&empty_set); 1771 sigemptyset(&blocked_set); 1772 1773 /* startup_child() must be called before the signal handlers get 1774 * installed below as they are inherited into the spawned process. 1775 * Also we do not need to be protected by them as during interruption 1776 * in the startup_child() mode we kill the spawned process anyway. 1777 */ 1778 if (argv[0]) { 1779 startup_child(argv); 1780 } 1781 1782 sa.sa_handler = SIG_IGN; 1783 sigemptyset(&sa.sa_mask); 1784 sa.sa_flags = 0; 1785 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */ 1786 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */ 1787 if (opt_intr != INTR_ANYWHERE) { 1788 if (opt_intr == INTR_BLOCK_TSTP_TOO) 1789 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */ 1790 /* 1791 * In interactive mode (if no -o OUTFILE, or -p PID is used), 1792 * fatal signals are blocked while syscall stop is processed, 1793 * and acted on in between, when waiting for new syscall stops. 1794 * In non-interactive mode, signals are ignored. 1795 */ 1796 if (opt_intr == INTR_WHILE_WAIT) { 1797 sigaddset(&blocked_set, SIGHUP); 1798 sigaddset(&blocked_set, SIGINT); 1799 sigaddset(&blocked_set, SIGQUIT); 1800 sigaddset(&blocked_set, SIGPIPE); 1801 sigaddset(&blocked_set, SIGTERM); 1802 sa.sa_handler = interrupt; 1803 } 1804 /* SIG_IGN, or set handler for these */ 1805 sigaction(SIGHUP, &sa, NULL); 1806 sigaction(SIGINT, &sa, NULL); 1807 sigaction(SIGQUIT, &sa, NULL); 1808 sigaction(SIGPIPE, &sa, NULL); 1809 sigaction(SIGTERM, &sa, NULL); 1810 } 1811 if (nprocs != 0 || daemonized_tracer) 1812 startup_attach(); 1813 1814 /* Do we want pids printed in our -o OUTFILE? 1815 * -ff: no (every pid has its own file); or 1816 * -f: yes (there can be more pids in the future); or 1817 * -p PID1,PID2: yes (there are already more than one pid) 1818 */ 1819 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1)); 1820} 1821 1822static struct tcb * 1823pid2tcb(int pid) 1824{ 1825 int i; 1826 1827 if (pid <= 0) 1828 return NULL; 1829 1830 for (i = 0; i < tcbtabsize; i++) { 1831 struct tcb *tcp = tcbtab[i]; 1832 if (tcp->pid == pid && (tcp->flags & TCB_INUSE)) 1833 return tcp; 1834 } 1835 1836 return NULL; 1837} 1838 1839static void 1840cleanup(void) 1841{ 1842 int i; 1843 struct tcb *tcp; 1844 int fatal_sig; 1845 1846 /* 'interrupted' is a volatile object, fetch it only once */ 1847 fatal_sig = interrupted; 1848 if (!fatal_sig) 1849 fatal_sig = SIGTERM; 1850 1851 for (i = 0; i < tcbtabsize; i++) { 1852 tcp = tcbtab[i]; 1853 if (!(tcp->flags & TCB_INUSE)) 1854 continue; 1855 if (debug_flag) 1856 fprintf(stderr, 1857 "cleanup: looking at pid %u\n", tcp->pid); 1858 if (tcp->flags & TCB_STRACE_CHILD) { 1859 kill(tcp->pid, SIGCONT); 1860 kill(tcp->pid, fatal_sig); 1861 } 1862 detach(tcp); 1863 } 1864 if (cflag) 1865 call_summary(shared_log); 1866} 1867 1868static void 1869interrupt(int sig) 1870{ 1871 interrupted = sig; 1872} 1873 1874static int 1875trace(void) 1876{ 1877 struct rusage ru; 1878 struct rusage *rup = cflag ? &ru : NULL; 1879#ifdef __WALL 1880 static int wait4_options = __WALL; 1881#endif 1882 1883 while (nprocs != 0) { 1884 int pid; 1885 int wait_errno; 1886 int status, sig; 1887 int stopped; 1888 struct tcb *tcp; 1889 unsigned event; 1890 1891 if (interrupted) 1892 return 0; 1893 if (interactive) 1894 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1895#ifdef __WALL 1896 pid = wait4(-1, &status, wait4_options, rup); 1897 if (pid < 0 && (wait4_options & __WALL) && errno == EINVAL) { 1898 /* this kernel does not support __WALL */ 1899 wait4_options &= ~__WALL; 1900 pid = wait4(-1, &status, wait4_options, rup); 1901 } 1902 if (pid < 0 && !(wait4_options & __WALL) && errno == ECHILD) { 1903 /* most likely a "cloned" process */ 1904 pid = wait4(-1, &status, __WCLONE, rup); 1905 if (pid < 0) { 1906 perror_msg("wait4(__WCLONE) failed"); 1907 } 1908 } 1909#else 1910 pid = wait4(-1, &status, 0, rup); 1911#endif /* __WALL */ 1912 wait_errno = errno; 1913 if (interactive) 1914 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1915 1916 if (pid < 0) { 1917 switch (wait_errno) { 1918 case EINTR: 1919 continue; 1920 case ECHILD: 1921 /* 1922 * We would like to verify this case 1923 * but sometimes a race in Solbourne's 1924 * version of SunOS sometimes reports 1925 * ECHILD before sending us SIGCHILD. 1926 */ 1927 return 0; 1928 default: 1929 errno = wait_errno; 1930 perror_msg("wait"); 1931 return -1; 1932 } 1933 } 1934 if (pid == popen_pid) { 1935 if (WIFEXITED(status) || WIFSIGNALED(status)) 1936 popen_pid = 0; 1937 continue; 1938 } 1939 1940 event = ((unsigned)status >> 16); 1941 if (debug_flag) { 1942 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16]; 1943 char evbuf[sizeof(",PTRACE_EVENT_?? (%u)") + sizeof(int)*3 /*paranoia:*/ + 16]; 1944 strcpy(buf, "???"); 1945 if (WIFSIGNALED(status)) 1946#ifdef WCOREDUMP 1947 sprintf(buf, "WIFSIGNALED,%ssig=%s", 1948 WCOREDUMP(status) ? "core," : "", 1949 signame(WTERMSIG(status))); 1950#else 1951 sprintf(buf, "WIFSIGNALED,sig=%s", 1952 signame(WTERMSIG(status))); 1953#endif 1954 if (WIFEXITED(status)) 1955 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status)); 1956 if (WIFSTOPPED(status)) 1957 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status))); 1958#ifdef WIFCONTINUED 1959 if (WIFCONTINUED(status)) 1960 strcpy(buf, "WIFCONTINUED"); 1961#endif 1962 evbuf[0] = '\0'; 1963 if (event != 0) { 1964 static const char *const event_names[] = { 1965 [PTRACE_EVENT_CLONE] = "CLONE", 1966 [PTRACE_EVENT_FORK] = "FORK", 1967 [PTRACE_EVENT_VFORK] = "VFORK", 1968 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE", 1969 [PTRACE_EVENT_EXEC] = "EXEC", 1970 [PTRACE_EVENT_EXIT] = "EXIT", 1971 }; 1972 const char *e; 1973 if (event < ARRAY_SIZE(event_names)) 1974 e = event_names[event]; 1975 else { 1976 sprintf(buf, "?? (%u)", event); 1977 e = buf; 1978 } 1979 sprintf(evbuf, ",PTRACE_EVENT_%s", e); 1980 } 1981 fprintf(stderr, " [wait(0x%04x) = %u] %s%s\n", status, pid, buf, evbuf); 1982 } 1983 1984 /* Look up 'pid' in our table. */ 1985 tcp = pid2tcb(pid); 1986 1987 if (!tcp) { 1988 if (followfork) { 1989 tcp = alloctcb(pid); 1990 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1991 newoutf(tcp); 1992 if (!qflag) 1993 fprintf(stderr, "Process %d attached\n", 1994 pid); 1995 } else { 1996 /* This can happen if a clone call used 1997 CLONE_PTRACE itself. */ 1998 if (WIFSTOPPED(status)) 1999 ptrace(PTRACE_CONT, pid, (char *) 0, 0); 2000 error_msg_and_die("Unknown pid: %u", pid); 2001 } 2002 } 2003 2004 clear_regs(); 2005 if (WIFSTOPPED(status)) 2006 get_regs(pid); 2007 2008 /* Under Linux, execve changes pid to thread leader's pid, 2009 * and we see this changed pid on EVENT_EXEC and later, 2010 * execve sysexit. Leader "disappears" without exit 2011 * notification. Let user know that, drop leader's tcb, 2012 * and fix up pid in execve thread's tcb. 2013 * Effectively, execve thread's tcb replaces leader's tcb. 2014 * 2015 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED 2016 * on exit syscall) in multithreaded programs exactly 2017 * in order to handle this case. 2018 * 2019 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0. 2020 * On 2.6 and earlier, it can return garbage. 2021 */ 2022 if (event == PTRACE_EVENT_EXEC && os_release >= KERNEL_VERSION(3,0,0)) { 2023 FILE *fp; 2024 struct tcb *execve_thread; 2025 long old_pid = 0; 2026 2027 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0) 2028 goto dont_switch_tcbs; 2029 if (old_pid <= 0 || old_pid == pid) 2030 goto dont_switch_tcbs; 2031 execve_thread = pid2tcb(old_pid); 2032 /* It should be !NULL, but I feel paranoid */ 2033 if (!execve_thread) 2034 goto dont_switch_tcbs; 2035 2036 if (execve_thread->curcol != 0) { 2037 /* 2038 * One case we are here is -ff: 2039 * try "strace -oLOG -ff test/threaded_execve" 2040 */ 2041 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid); 2042 /*execve_thread->curcol = 0; - no need, see code below */ 2043 } 2044 /* Swap output FILEs (needed for -ff) */ 2045 fp = execve_thread->outf; 2046 execve_thread->outf = tcp->outf; 2047 tcp->outf = fp; 2048 /* And their column positions */ 2049 execve_thread->curcol = tcp->curcol; 2050 tcp->curcol = 0; 2051 /* Drop leader, but close execve'd thread outfile (if -ff) */ 2052 droptcb(tcp); 2053 /* Switch to the thread, reusing leader's outfile and pid */ 2054 tcp = execve_thread; 2055 tcp->pid = pid; 2056 if (cflag != CFLAG_ONLY_STATS) { 2057 printleader(tcp); 2058 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid); 2059 line_ended(); 2060 tcp->flags |= TCB_REPRINT; 2061 } 2062 } 2063 dont_switch_tcbs: 2064 2065 if (event == PTRACE_EVENT_EXEC && detach_on_execve) { 2066 if (!skip_startup_execve) 2067 detach(tcp); 2068 /* This was initial execve for "strace PROG". Skip. */ 2069 skip_startup_execve = 0; 2070 } 2071 2072 /* Set current output file */ 2073 current_tcp = tcp; 2074 2075 if (cflag) { 2076 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime); 2077 tcp->stime = ru.ru_stime; 2078 } 2079 2080 if (WIFSIGNALED(status)) { 2081 if (pid == strace_child) 2082 exit_code = 0x100 | WTERMSIG(status); 2083 if (cflag != CFLAG_ONLY_STATS 2084 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL) 2085 ) { 2086 printleader(tcp); 2087#ifdef WCOREDUMP 2088 tprintf("+++ killed by %s %s+++\n", 2089 signame(WTERMSIG(status)), 2090 WCOREDUMP(status) ? "(core dumped) " : ""); 2091#else 2092 tprintf("+++ killed by %s +++\n", 2093 signame(WTERMSIG(status))); 2094#endif 2095 line_ended(); 2096 } 2097 droptcb(tcp); 2098 continue; 2099 } 2100 if (WIFEXITED(status)) { 2101 if (pid == strace_child) 2102 exit_code = WEXITSTATUS(status); 2103 if (cflag != CFLAG_ONLY_STATS) { 2104 printleader(tcp); 2105 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status)); 2106 line_ended(); 2107 } 2108 droptcb(tcp); 2109 continue; 2110 } 2111 if (!WIFSTOPPED(status)) { 2112 fprintf(stderr, "PANIC: pid %u not stopped\n", pid); 2113 droptcb(tcp); 2114 continue; 2115 } 2116 2117 /* Is this the very first time we see this tracee stopped? */ 2118 if (tcp->flags & TCB_STARTUP) { 2119 if (debug_flag) 2120 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n", tcp->pid); 2121 tcp->flags &= ~TCB_STARTUP; 2122 if (tcp->flags & TCB_BPTSET) { 2123 /* 2124 * One example is a breakpoint inherited from 2125 * parent through fork(). 2126 */ 2127 if (clearbpt(tcp) < 0) { 2128 /* Pretty fatal */ 2129 droptcb(tcp); 2130 cleanup(); 2131 return -1; 2132 } 2133 } 2134 if (ptrace_setoptions) { 2135 if (debug_flag) 2136 fprintf(stderr, "setting opts %x on pid %d\n", ptrace_setoptions, tcp->pid); 2137 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) { 2138 if (errno != ESRCH) { 2139 /* Should never happen, really */ 2140 perror_msg_and_die("PTRACE_SETOPTIONS"); 2141 } 2142 } 2143 } 2144 } 2145 2146 sig = WSTOPSIG(status); 2147 2148 if (event != 0) { 2149 /* Ptrace event */ 2150#if USE_SEIZE 2151 if (event == PTRACE_EVENT_STOP) { 2152 /* 2153 * PTRACE_INTERRUPT-stop or group-stop. 2154 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here. 2155 */ 2156 if (sig == SIGSTOP 2157 || sig == SIGTSTP 2158 || sig == SIGTTIN 2159 || sig == SIGTTOU 2160 ) { 2161 stopped = 1; 2162 goto show_stopsig; 2163 } 2164 } 2165#endif 2166 goto restart_tracee_with_sig_0; 2167 } 2168 2169 /* Is this post-attach SIGSTOP? 2170 * Interestingly, the process may stop 2171 * with STOPSIG equal to some other signal 2172 * than SIGSTOP if we happend to attach 2173 * just before the process takes a signal. 2174 */ 2175 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) { 2176 if (debug_flag) 2177 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid); 2178 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP; 2179 goto restart_tracee_with_sig_0; 2180 } 2181 2182 if (sig != syscall_trap_sig) { 2183 siginfo_t si; 2184 2185 /* Nonzero (true) if tracee is stopped by signal 2186 * (as opposed to "tracee received signal"). 2187 * TODO: shouldn't we check for errno == EINVAL too? 2188 * We can get ESRCH instead, you know... 2189 */ 2190 stopped = (ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0); 2191#if USE_SEIZE 2192 show_stopsig: 2193#endif 2194 if (cflag != CFLAG_ONLY_STATS 2195 && (qual_flags[sig] & QUAL_SIGNAL) 2196 ) { 2197#if defined(PT_CR_IPSR) && defined(PT_CR_IIP) 2198 long pc = 0; 2199 long psr = 0; 2200 2201 upeek(tcp, PT_CR_IPSR, &psr); 2202 upeek(tcp, PT_CR_IIP, &pc); 2203 2204# define PSR_RI 41 2205 pc += (psr >> PSR_RI) & 0x3; 2206# define PC_FORMAT_STR " @ %lx" 2207# define PC_FORMAT_ARG , pc 2208#else 2209# define PC_FORMAT_STR "" 2210# define PC_FORMAT_ARG /* nothing */ 2211#endif 2212 printleader(tcp); 2213 if (!stopped) { 2214 tprintf("--- %s ", signame(sig)); 2215 printsiginfo(&si, verbose(tcp)); 2216 tprintf(PC_FORMAT_STR " ---\n" 2217 PC_FORMAT_ARG); 2218 } else 2219 tprintf("--- stopped by %s" PC_FORMAT_STR " ---\n", 2220 signame(sig) 2221 PC_FORMAT_ARG); 2222 line_ended(); 2223 } 2224 2225 if (!stopped) 2226 /* It's signal-delivery-stop. Inject the signal */ 2227 goto restart_tracee; 2228 2229 /* It's group-stop */ 2230#if USE_SEIZE 2231 if (use_seize) { 2232 /* 2233 * This ends ptrace-stop, but does *not* end group-stop. 2234 * This makes stopping signals work properly on straced process 2235 * (that is, process really stops. It used to continue to run). 2236 */ 2237 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) { 2238 cleanup(); 2239 return -1; 2240 } 2241 continue; 2242 } 2243 /* We don't have PTRACE_LISTEN support... */ 2244#endif 2245 goto restart_tracee; 2246 } 2247 2248 /* We handled quick cases, we are permitted to interrupt now. */ 2249 if (interrupted) 2250 return 0; 2251 2252 /* This should be syscall entry or exit. 2253 * (Or it still can be that pesky post-execve SIGTRAP!) 2254 * Handle it. 2255 */ 2256 if (trace_syscall(tcp) < 0) { 2257 /* ptrace() failed in trace_syscall(). 2258 * Likely a result of process disappearing mid-flight. 2259 * Observed case: exit_group() or SIGKILL terminating 2260 * all processes in thread group. 2261 * We assume that ptrace error was caused by process death. 2262 * We used to detach(tcp) here, but since we no longer 2263 * implement "detach before death" policy/hack, 2264 * we can let this process to report its death to us 2265 * normally, via WIFEXITED or WIFSIGNALED wait status. 2266 */ 2267 continue; 2268 } 2269 restart_tracee_with_sig_0: 2270 sig = 0; 2271 restart_tracee: 2272 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) { 2273 cleanup(); 2274 return -1; 2275 } 2276 } 2277 return 0; 2278} 2279 2280int 2281main(int argc, char *argv[]) 2282{ 2283 init(argc, argv); 2284 2285 /* Run main tracing loop */ 2286 if (trace() < 0) 2287 return 1; 2288 2289 cleanup(); 2290 fflush(NULL); 2291 if (shared_log != stderr) 2292 fclose(shared_log); 2293 if (popen_pid) { 2294 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR) 2295 ; 2296 } 2297 if (exit_code > 0xff) { 2298 /* Avoid potential core file clobbering. */ 2299 struct rlimit rlim = {0, 0}; 2300 setrlimit(RLIMIT_CORE, &rlim); 2301 2302 /* Child was killed by a signal, mimic that. */ 2303 exit_code &= 0xff; 2304 signal(exit_code, SIG_DFL); 2305 raise(exit_code); 2306 /* Paranoia - what if this signal is not fatal? 2307 Exit with 128 + signo then. */ 2308 exit_code += 128; 2309 } 2310 2311 return exit_code; 2312} 2313