strace.c revision f1669e7975cb8d67448d52d9ae7dde3301d27273
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#ifdef HAVE_PRCTL 43# include <sys/prctl.h> 44#endif 45#if defined(IA64) 46# include <asm/ptrace_offsets.h> 47#endif 48/* In some libc, these aren't declared. Do it ourself: */ 49extern char **environ; 50extern int optind; 51extern char *optarg; 52 53 54#if defined __NR_tkill 55# define my_tkill(tid, sig) syscall(__NR_tkill, (tid), (sig)) 56#else 57 /* kill() may choose arbitrarily the target task of the process group 58 while we later wait on a that specific TID. PID process waits become 59 TID task specific waits for a process under ptrace(2). */ 60# warning "tkill(2) not available, risk of strace hangs!" 61# define my_tkill(tid, sig) kill((tid), (sig)) 62#endif 63 64/* Glue for systems without a MMU that cannot provide fork() */ 65#if !defined(HAVE_FORK) 66# undef NOMMU_SYSTEM 67# define NOMMU_SYSTEM 1 68#endif 69#if NOMMU_SYSTEM 70# define fork() vfork() 71#endif 72 73cflag_t cflag = CFLAG_NONE; 74unsigned int followfork = 0; 75unsigned int ptrace_setoptions = 0; 76unsigned int xflag = 0; 77bool need_fork_exec_workarounds = 0; 78bool debug_flag = 0; 79bool Tflag = 0; 80unsigned int qflag = 0; 81/* Which WSTOPSIG(status) value marks syscall traps? */ 82static unsigned int syscall_trap_sig = SIGTRAP; 83static unsigned int tflag = 0; 84static bool iflag = 0; 85static bool rflag = 0; 86static bool print_pid_pfx = 0; 87 88/* -I n */ 89enum { 90 INTR_NOT_SET = 0, 91 INTR_ANYWHERE = 1, /* don't block/ignore any signals */ 92 INTR_WHILE_WAIT = 2, /* block fatal signals while decoding syscall. default */ 93 INTR_NEVER = 3, /* block fatal signals. default if '-o FILE PROG' */ 94 INTR_BLOCK_TSTP_TOO = 4, /* block fatal signals and SIGTSTP (^Z) */ 95 NUM_INTR_OPTS 96}; 97static int opt_intr; 98/* We play with signal mask only if this mode is active: */ 99#define interactive (opt_intr == INTR_WHILE_WAIT) 100 101/* 102 * daemonized_tracer supports -D option. 103 * With this option, strace forks twice. 104 * Unlike normal case, with -D *grandparent* process exec's, 105 * becoming a traced process. Child exits (this prevents traced process 106 * from having children it doesn't expect to have), and grandchild 107 * attaches to grandparent similarly to strace -p PID. 108 * This allows for more transparent interaction in cases 109 * when process and its parent are communicating via signals, 110 * wait() etc. Without -D, strace process gets lodged in between, 111 * disrupting parent<->child link. 112 */ 113static bool daemonized_tracer = 0; 114 115#if USE_SEIZE 116static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP; 117# define use_seize (post_attach_sigstop == 0) 118#else 119# define post_attach_sigstop TCB_IGNORE_ONE_SIGSTOP 120# define use_seize 0 121#endif 122 123/* Sometimes we want to print only succeeding syscalls. */ 124bool not_failing_only = 0; 125 126/* Show path associated with fd arguments */ 127bool show_fd_path = 0; 128 129static bool detach_on_execve = 0; 130/* Are we "strace PROG" and need to skip detach on first execve? */ 131static bool skip_one_b_execve = 0; 132/* Are we "strace PROG" and need to hide everything until execve? */ 133bool hide_log_until_execve = 0; 134 135static int exit_code = 0; 136static int strace_child = 0; 137static int strace_tracer_pid = 0; 138 139static char *username = NULL; 140static uid_t run_uid; 141static gid_t run_gid; 142 143unsigned int max_strlen = DEFAULT_STRLEN; 144static int acolumn = DEFAULT_ACOLUMN; 145static char *acolumn_spaces; 146 147static char *outfname = NULL; 148/* If -ff, points to stderr. Else, it's our common output log */ 149static FILE *shared_log; 150 151struct tcb *printing_tcp = NULL; 152static struct tcb *current_tcp; 153 154static struct tcb **tcbtab; 155static unsigned int nprocs, tcbtabsize; 156static const char *progname; 157 158unsigned os_release; /* generated from uname()'s u.release */ 159 160static int detach(struct tcb *tcp); 161static int trace(void); 162static void cleanup(void); 163static void interrupt(int sig); 164static sigset_t empty_set, blocked_set; 165 166#ifdef HAVE_SIG_ATOMIC_T 167static volatile sig_atomic_t interrupted; 168#else 169static volatile int interrupted; 170#endif 171 172#ifndef HAVE_STRERROR 173 174#if !HAVE_DECL_SYS_ERRLIST 175extern int sys_nerr; 176extern char *sys_errlist[]; 177#endif 178 179const char * 180strerror(int err_no) 181{ 182 static char buf[sizeof("Unknown error %d") + sizeof(int)*3]; 183 184 if (err_no < 1 || err_no >= sys_nerr) { 185 sprintf(buf, "Unknown error %d", err_no); 186 return buf; 187 } 188 return sys_errlist[err_no]; 189} 190 191#endif /* HAVE_STERRROR */ 192 193static void 194usage(FILE *ofp, int exitval) 195{ 196 fprintf(ofp, "\ 197usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\ 198 [-a column] [-o file] [-s strsize] [-P path]...\n\ 199 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 200 or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\ 201 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 202-c -- count time, calls, and errors for each syscall and report summary\n\ 203-C -- like -c but also print regular output\n\ 204-d -- enable debug output to stderr\n\ 205-D -- run tracer process as a detached grandchild, not as parent\n\ 206-f -- follow forks, -ff -- with output into separate files\n\ 207-i -- print instruction pointer at time of syscall\n\ 208-q -- suppress messages about attaching, detaching, etc.\n\ 209-r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs\n\ 210-T -- print time spent in each syscall\n\ 211-v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\ 212-x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\ 213-y -- print paths associated with file descriptor arguments\n\ 214-h -- print help message, -V -- print version\n\ 215-a column -- alignment COLUMN for printing syscall results (default %d)\n\ 216-b execve -- detach on this syscall\n\ 217-e expr -- a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\ 218 options: trace, abbrev, verbose, raw, signal, read, write\n\ 219-I interruptible --\n\ 220 1: no signals are blocked\n\ 221 2: fatal signals are blocked while decoding syscall (default)\n\ 222 3: fatal signals are always blocked (default if '-o FILE PROG')\n\ 223 4: fatal signals and SIGTSTP (^Z) are always blocked\n\ 224 (useful to make 'strace -o FILE PROG' not stop on ^Z)\n\ 225-o file -- send trace output to FILE instead of stderr\n\ 226-O overhead -- set overhead for tracing syscalls to OVERHEAD usecs\n\ 227-p pid -- trace process with process id PID, may be repeated\n\ 228-s strsize -- limit length of print strings to STRSIZE chars (default %d)\n\ 229-S sortby -- sort syscall counts by: time, calls, name, nothing (default %s)\n\ 230-u username -- run command as username handling setuid and/or setgid\n\ 231-E var=val -- put var=val in the environment for command\n\ 232-E var -- remove var from the environment for command\n\ 233-P path -- trace accesses to path\n\ 234" 235/* ancient, no one should use it 236-F -- attempt to follow vforks (deprecated, use -f)\n\ 237 */ 238/* this is broken, so don't document it 239-z -- print only succeeding syscalls\n\ 240 */ 241, DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY); 242 exit(exitval); 243} 244 245static void die(void) __attribute__ ((noreturn)); 246static void die(void) 247{ 248 if (strace_tracer_pid == getpid()) { 249 cflag = 0; 250 cleanup(); 251 } 252 exit(1); 253} 254 255static void verror_msg(int err_no, const char *fmt, va_list p) 256{ 257 char *msg; 258 259 fflush(NULL); 260 261 /* We want to print entire message with single fprintf to ensure 262 * message integrity if stderr is shared with other programs. 263 * Thus we use vasprintf + single fprintf. 264 */ 265 msg = NULL; 266 if (vasprintf(&msg, fmt, p) >= 0) { 267 if (err_no) 268 fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no)); 269 else 270 fprintf(stderr, "%s: %s\n", progname, msg); 271 free(msg); 272 } else { 273 /* malloc in vasprintf failed, try it without malloc */ 274 fprintf(stderr, "%s: ", progname); 275 vfprintf(stderr, fmt, p); 276 if (err_no) 277 fprintf(stderr, ": %s\n", strerror(err_no)); 278 else 279 putc('\n', stderr); 280 } 281 /* We don't switch stderr to buffered, thus fprintf(stderr) 282 * always flushes its output and this is not necessary: */ 283 /* fflush(stderr); */ 284} 285 286void error_msg(const char *fmt, ...) 287{ 288 va_list p; 289 va_start(p, fmt); 290 verror_msg(0, fmt, p); 291 va_end(p); 292} 293 294void error_msg_and_die(const char *fmt, ...) 295{ 296 va_list p; 297 va_start(p, fmt); 298 verror_msg(0, fmt, p); 299 die(); 300} 301 302void perror_msg(const char *fmt, ...) 303{ 304 va_list p; 305 va_start(p, fmt); 306 verror_msg(errno, fmt, p); 307 va_end(p); 308} 309 310void perror_msg_and_die(const char *fmt, ...) 311{ 312 va_list p; 313 va_start(p, fmt); 314 verror_msg(errno, fmt, p); 315 die(); 316} 317 318void die_out_of_memory(void) 319{ 320 static bool recursed = 0; 321 if (recursed) 322 exit(1); 323 recursed = 1; 324 error_msg_and_die("Out of memory"); 325} 326 327static void 328error_opt_arg(int opt, const char *arg) 329{ 330 error_msg_and_die("Invalid -%c argument: '%s'", opt, arg); 331} 332 333#if USE_SEIZE 334static int 335ptrace_attach_or_seize(int pid) 336{ 337 int r; 338 if (!use_seize) 339 return ptrace(PTRACE_ATTACH, pid, 0, 0); 340 r = ptrace(PTRACE_SEIZE, pid, 0, 0); 341 if (r) 342 return r; 343 r = ptrace(PTRACE_INTERRUPT, pid, 0, 0); 344 return r; 345} 346#else 347# define ptrace_attach_or_seize(pid) ptrace(PTRACE_ATTACH, (pid), 0, 0) 348#endif 349 350/* 351 * Used when we want to unblock stopped traced process. 352 * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL. 353 * Returns 0 on success or if error was ESRCH 354 * (presumably process was killed while we talk to it). 355 * Otherwise prints error message and returns -1. 356 */ 357static int 358ptrace_restart(int op, struct tcb *tcp, int sig) 359{ 360 int err; 361 const char *msg; 362 363 errno = 0; 364 ptrace(op, tcp->pid, (void *) 0, (long) sig); 365 err = errno; 366 if (!err) 367 return 0; 368 369 msg = "SYSCALL"; 370 if (op == PTRACE_CONT) 371 msg = "CONT"; 372 if (op == PTRACE_DETACH) 373 msg = "DETACH"; 374#ifdef PTRACE_LISTEN 375 if (op == PTRACE_LISTEN) 376 msg = "LISTEN"; 377#endif 378 /* 379 * Why curcol != 0? Otherwise sometimes we get this: 380 * 381 * 10252 kill(10253, SIGKILL) = 0 382 * <ptrace(SYSCALL,10252):No such process>10253 ...next decode... 383 * 384 * 10252 died after we retrieved syscall exit data, 385 * but before we tried to restart it. Log looks ugly. 386 */ 387 if (current_tcp && current_tcp->curcol != 0) { 388 tprintf(" <ptrace(%s):%s>\n", msg, strerror(err)); 389 line_ended(); 390 } 391 if (err == ESRCH) 392 return 0; 393 errno = err; 394 perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig); 395 return -1; 396} 397 398static void 399set_cloexec_flag(int fd) 400{ 401 int flags, newflags; 402 403 flags = fcntl(fd, F_GETFD); 404 if (flags < 0) { 405 /* Can happen only if fd is bad. 406 * Should never happen: if it does, we have a bug 407 * in the caller. Therefore we just abort 408 * instead of propagating the error. 409 */ 410 perror_msg_and_die("fcntl(%d, F_GETFD)", fd); 411 } 412 413 newflags = flags | FD_CLOEXEC; 414 if (flags == newflags) 415 return; 416 417 fcntl(fd, F_SETFD, newflags); /* never fails */ 418} 419 420static void kill_save_errno(pid_t pid, int sig) 421{ 422 int saved_errno = errno; 423 424 (void) kill(pid, sig); 425 errno = saved_errno; 426} 427 428/* 429 * When strace is setuid executable, we have to swap uids 430 * before and after filesystem and process management operations. 431 */ 432static void 433swap_uid(void) 434{ 435 int euid = geteuid(), uid = getuid(); 436 437 if (euid != uid && setreuid(euid, uid) < 0) { 438 perror_msg_and_die("setreuid"); 439 } 440} 441 442#if _LFS64_LARGEFILE 443# define fopen_for_output fopen64 444# define struct_stat struct stat64 445# define stat_file stat64 446# define struct_dirent struct dirent64 447# define read_dir readdir64 448# define struct_rlimit struct rlimit64 449# define set_rlimit setrlimit64 450#else 451# define fopen_for_output fopen 452# define struct_stat struct stat 453# define stat_file stat 454# define struct_dirent struct dirent 455# define read_dir readdir 456# define struct_rlimit struct rlimit 457# define set_rlimit setrlimit 458#endif 459 460static FILE * 461strace_fopen(const char *path) 462{ 463 FILE *fp; 464 465 swap_uid(); 466 fp = fopen_for_output(path, "w"); 467 if (!fp) 468 perror_msg_and_die("Can't fopen '%s'", path); 469 swap_uid(); 470 set_cloexec_flag(fileno(fp)); 471 return fp; 472} 473 474static int popen_pid = 0; 475 476#ifndef _PATH_BSHELL 477# define _PATH_BSHELL "/bin/sh" 478#endif 479 480/* 481 * We cannot use standard popen(3) here because we have to distinguish 482 * popen child process from other processes we trace, and standard popen(3) 483 * does not export its child's pid. 484 */ 485static FILE * 486strace_popen(const char *command) 487{ 488 FILE *fp; 489 int fds[2]; 490 491 swap_uid(); 492 if (pipe(fds) < 0) 493 perror_msg_and_die("pipe"); 494 495 set_cloexec_flag(fds[1]); /* never fails */ 496 497 popen_pid = vfork(); 498 if (popen_pid == -1) 499 perror_msg_and_die("vfork"); 500 501 if (popen_pid == 0) { 502 /* child */ 503 close(fds[1]); 504 if (fds[0] != 0) { 505 if (dup2(fds[0], 0)) 506 perror_msg_and_die("dup2"); 507 close(fds[0]); 508 } 509 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 510 perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL); 511 } 512 513 /* parent */ 514 close(fds[0]); 515 swap_uid(); 516 fp = fdopen(fds[1], "w"); 517 if (!fp) 518 die_out_of_memory(); 519 return fp; 520} 521 522void 523tprintf(const char *fmt, ...) 524{ 525 va_list args; 526 527 va_start(args, fmt); 528 if (current_tcp) { 529 int n = strace_vfprintf(current_tcp->outf, fmt, args); 530 if (n < 0) { 531 if (current_tcp->outf != stderr) 532 perror_msg("%s", outfname); 533 } else 534 current_tcp->curcol += n; 535 } 536 va_end(args); 537} 538 539void 540tprints(const char *str) 541{ 542 if (current_tcp) { 543 int n = fputs_unlocked(str, current_tcp->outf); 544 if (n >= 0) { 545 current_tcp->curcol += strlen(str); 546 return; 547 } 548 if (current_tcp->outf != stderr) 549 perror_msg("%s", outfname); 550 } 551} 552 553void 554line_ended(void) 555{ 556 if (current_tcp) { 557 current_tcp->curcol = 0; 558 fflush(current_tcp->outf); 559 } 560 if (printing_tcp) { 561 printing_tcp->curcol = 0; 562 printing_tcp = NULL; 563 } 564} 565 566void 567printleader(struct tcb *tcp) 568{ 569 /* If -ff, "previous tcb we printed" is always the same as current, 570 * because we have per-tcb output files. 571 */ 572 if (followfork >= 2) 573 printing_tcp = tcp; 574 575 if (printing_tcp) { 576 current_tcp = printing_tcp; 577 if (printing_tcp->curcol != 0 && (followfork < 2 || printing_tcp == tcp)) { 578 /* 579 * case 1: we have a shared log (i.e. not -ff), and last line 580 * wasn't finished (same or different tcb, doesn't matter). 581 * case 2: split log, we are the same tcb, but our last line 582 * didn't finish ("SIGKILL nuked us after syscall entry" etc). 583 */ 584 tprints(" <unfinished ...>\n"); 585 printing_tcp->curcol = 0; 586 } 587 } 588 589 printing_tcp = tcp; 590 current_tcp = tcp; 591 current_tcp->curcol = 0; 592 593 if (print_pid_pfx) 594 tprintf("%-5d ", tcp->pid); 595 else if (nprocs > 1 && !outfname) 596 tprintf("[pid %5u] ", tcp->pid); 597 598 if (tflag) { 599 char str[sizeof("HH:MM:SS")]; 600 struct timeval tv, dtv; 601 static struct timeval otv; 602 603 gettimeofday(&tv, NULL); 604 if (rflag) { 605 if (otv.tv_sec == 0) 606 otv = tv; 607 tv_sub(&dtv, &tv, &otv); 608 tprintf("%6ld.%06ld ", 609 (long) dtv.tv_sec, (long) dtv.tv_usec); 610 otv = tv; 611 } 612 else if (tflag > 2) { 613 tprintf("%ld.%06ld ", 614 (long) tv.tv_sec, (long) tv.tv_usec); 615 } 616 else { 617 time_t local = tv.tv_sec; 618 strftime(str, sizeof(str), "%T", localtime(&local)); 619 if (tflag > 1) 620 tprintf("%s.%06ld ", str, (long) tv.tv_usec); 621 else 622 tprintf("%s ", str); 623 } 624 } 625 if (iflag) 626 printcall(tcp); 627} 628 629void 630tabto(void) 631{ 632 if (current_tcp->curcol < acolumn) 633 tprints(acolumn_spaces + current_tcp->curcol); 634} 635 636/* Should be only called directly *after successful attach* to a tracee. 637 * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>" 638 * may create bogus empty FILE.<nonexistant_pid>, and then die. 639 */ 640static void 641newoutf(struct tcb *tcp) 642{ 643 tcp->outf = shared_log; /* if not -ff mode, the same file is for all */ 644 if (followfork >= 2) { 645 char name[520 + sizeof(int) * 3]; 646 sprintf(name, "%.512s.%u", outfname, tcp->pid); 647 tcp->outf = strace_fopen(name); 648 } 649} 650 651static void 652expand_tcbtab(void) 653{ 654 /* Allocate some more TCBs and expand the table. 655 We don't want to relocate the TCBs because our 656 callers have pointers and it would be a pain. 657 So tcbtab is a table of pointers. Since we never 658 free the TCBs, we allocate a single chunk of many. */ 659 int i = tcbtabsize; 660 struct tcb *newtcbs = calloc(tcbtabsize, sizeof(newtcbs[0])); 661 struct tcb **newtab = realloc(tcbtab, tcbtabsize * 2 * sizeof(tcbtab[0])); 662 if (!newtab || !newtcbs) 663 die_out_of_memory(); 664 tcbtabsize *= 2; 665 tcbtab = newtab; 666 while (i < tcbtabsize) 667 tcbtab[i++] = newtcbs++; 668} 669 670static struct tcb * 671alloctcb(int pid) 672{ 673 int i; 674 struct tcb *tcp; 675 676 if (nprocs == tcbtabsize) 677 expand_tcbtab(); 678 679 for (i = 0; i < tcbtabsize; i++) { 680 tcp = tcbtab[i]; 681 if ((tcp->flags & TCB_INUSE) == 0) { 682 memset(tcp, 0, sizeof(*tcp)); 683 tcp->pid = pid; 684 tcp->flags = TCB_INUSE; 685#if SUPPORTED_PERSONALITIES > 1 686 tcp->currpers = current_personality; 687#endif 688 nprocs++; 689 if (debug_flag) 690 fprintf(stderr, "new tcb for pid %d, active tcbs:%d\n", tcp->pid, nprocs); 691 return tcp; 692 } 693 } 694 error_msg_and_die("bug in alloctcb"); 695} 696 697static void 698droptcb(struct tcb *tcp) 699{ 700 if (tcp->pid == 0) 701 return; 702 703 nprocs--; 704 if (debug_flag) 705 fprintf(stderr, "dropped tcb for pid %d, %d remain\n", tcp->pid, nprocs); 706 707 if (tcp->outf) { 708 if (followfork >= 2) { 709 if (tcp->curcol != 0) 710 fprintf(tcp->outf, " <detached ...>\n"); 711 fclose(tcp->outf); 712 } else { 713 if (printing_tcp == tcp && tcp->curcol != 0) 714 fprintf(tcp->outf, " <detached ...>\n"); 715 fflush(tcp->outf); 716 } 717 } 718 719 if (current_tcp == tcp) 720 current_tcp = NULL; 721 if (printing_tcp == tcp) 722 printing_tcp = NULL; 723 724 memset(tcp, 0, sizeof(*tcp)); 725} 726 727/* Detach traced process. 728 * Never call DETACH twice on the same process as both unattached and 729 * attached-unstopped processes give the same ESRCH. For unattached process we 730 * would SIGSTOP it and wait for its SIGSTOP notification forever. 731 */ 732static int 733detach(struct tcb *tcp) 734{ 735 int error; 736 int status, sigstop_expected; 737 738 if (tcp->flags & TCB_BPTSET) 739 clearbpt(tcp); 740 741 /* 742 * Linux wrongly insists the child be stopped 743 * before detaching. Arghh. We go through hoops 744 * to make a clean break of things. 745 */ 746#if defined(SPARC) 747# undef PTRACE_DETACH 748# define PTRACE_DETACH PTRACE_SUNDETACH 749#endif 750 751 error = 0; 752 sigstop_expected = 0; 753 if (tcp->flags & TCB_ATTACHED) { 754 /* 755 * We attached but possibly didn't see the expected SIGSTOP. 756 * We must catch exactly one as otherwise the detached process 757 * would be left stopped (process state T). 758 */ 759 sigstop_expected = (tcp->flags & TCB_IGNORE_ONE_SIGSTOP); 760 error = ptrace(PTRACE_DETACH, tcp->pid, (char *) 1, 0); 761 if (error == 0) { 762 /* On a clear day, you can see forever. */ 763 } 764 else if (errno != ESRCH) { 765 /* Shouldn't happen. */ 766 perror_msg("detach: ptrace(PTRACE_DETACH, ...)"); 767 } 768 else if (my_tkill(tcp->pid, 0) < 0) { 769 if (errno != ESRCH) 770 perror_msg("detach: checking sanity"); 771 } 772 else if (!sigstop_expected && my_tkill(tcp->pid, SIGSTOP) < 0) { 773 if (errno != ESRCH) 774 perror_msg("detach: stopping child"); 775 } 776 else 777 sigstop_expected = 1; 778 } 779 780 if (sigstop_expected) { 781 for (;;) { 782#ifdef __WALL 783 if (waitpid(tcp->pid, &status, __WALL) < 0) { 784 if (errno == ECHILD) /* Already gone. */ 785 break; 786 if (errno != EINVAL) { 787 perror_msg("detach: waiting"); 788 break; 789 } 790#endif /* __WALL */ 791 /* No __WALL here. */ 792 if (waitpid(tcp->pid, &status, 0) < 0) { 793 if (errno != ECHILD) { 794 perror_msg("detach: waiting"); 795 break; 796 } 797#ifdef __WCLONE 798 /* If no processes, try clones. */ 799 if (waitpid(tcp->pid, &status, __WCLONE) < 0) { 800 if (errno != ECHILD) 801 perror_msg("detach: waiting"); 802 break; 803 } 804#endif /* __WCLONE */ 805 } 806#ifdef __WALL 807 } 808#endif 809 if (!WIFSTOPPED(status)) { 810 /* Au revoir, mon ami. */ 811 break; 812 } 813 if (WSTOPSIG(status) == SIGSTOP) { 814 ptrace_restart(PTRACE_DETACH, tcp, 0); 815 break; 816 } 817 error = ptrace_restart(PTRACE_CONT, tcp, 818 WSTOPSIG(status) == syscall_trap_sig ? 0 819 : WSTOPSIG(status)); 820 if (error < 0) 821 break; 822 } 823 } 824 825 if (!qflag && (tcp->flags & TCB_ATTACHED)) 826 fprintf(stderr, "Process %u detached\n", tcp->pid); 827 828 droptcb(tcp); 829 830 return error; 831} 832 833static void 834process_opt_p_list(char *opt) 835{ 836 while (*opt) { 837 /* 838 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`". 839 * pidof uses space as delim, pgrep uses newline. :( 840 */ 841 int pid; 842 char *delim = opt + strcspn(opt, ", \n\t"); 843 char c = *delim; 844 845 *delim = '\0'; 846 pid = string_to_uint(opt); 847 if (pid <= 0) { 848 error_msg_and_die("Invalid process id: '%s'", opt); 849 } 850 if (pid == strace_tracer_pid) { 851 error_msg_and_die("I'm sorry, I can't let you do that, Dave."); 852 } 853 *delim = c; 854 alloctcb(pid); 855 if (c == '\0') 856 break; 857 opt = delim + 1; 858 } 859} 860 861static void 862startup_attach(void) 863{ 864 int tcbi; 865 struct tcb *tcp; 866 867 /* 868 * Block user interruptions as we would leave the traced 869 * process stopped (process state T) if we would terminate in 870 * between PTRACE_ATTACH and wait4() on SIGSTOP. 871 * We rely on cleanup() from this point on. 872 */ 873 if (interactive) 874 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 875 876 if (daemonized_tracer) { 877 pid_t pid = fork(); 878 if (pid < 0) { 879 perror_msg_and_die("fork"); 880 } 881 if (pid) { /* parent */ 882 /* 883 * Wait for grandchild to attach to straced process 884 * (grandparent). Grandchild SIGKILLs us after it attached. 885 * Grandparent's wait() is unblocked by our death, 886 * it proceeds to exec the straced program. 887 */ 888 pause(); 889 _exit(0); /* paranoia */ 890 } 891 /* grandchild */ 892 /* We will be the tracer process. Remember our new pid: */ 893 strace_tracer_pid = getpid(); 894 } 895 896 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) { 897 tcp = tcbtab[tcbi]; 898 899 if (!(tcp->flags & TCB_INUSE)) 900 continue; 901 902 /* Is this a process we should attach to, but not yet attached? */ 903 if (tcp->flags & TCB_ATTACHED) 904 continue; /* no, we already attached it */ 905 906 if (followfork && !daemonized_tracer) { 907 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3]; 908 DIR *dir; 909 910 sprintf(procdir, "/proc/%d/task", tcp->pid); 911 dir = opendir(procdir); 912 if (dir != NULL) { 913 unsigned int ntid = 0, nerr = 0; 914 struct_dirent *de; 915 916 while ((de = read_dir(dir)) != NULL) { 917 struct tcb *cur_tcp; 918 int tid; 919 920 if (de->d_fileno == 0) 921 continue; 922 /* we trust /proc filesystem */ 923 tid = atoi(de->d_name); 924 if (tid <= 0) 925 continue; 926 ++ntid; 927 if (ptrace_attach_or_seize(tid) < 0) { 928 ++nerr; 929 if (debug_flag) 930 fprintf(stderr, "attach to pid %d failed\n", tid); 931 continue; 932 } 933 if (debug_flag) 934 fprintf(stderr, "attach to pid %d succeeded\n", tid); 935 cur_tcp = tcp; 936 if (tid != tcp->pid) 937 cur_tcp = alloctcb(tid); 938 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 939 newoutf(cur_tcp); 940 } 941 closedir(dir); 942 if (interactive) { 943 sigprocmask(SIG_SETMASK, &empty_set, NULL); 944 if (interrupted) 945 goto ret; 946 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 947 } 948 ntid -= nerr; 949 if (ntid == 0) { 950 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 951 droptcb(tcp); 952 continue; 953 } 954 if (!qflag) { 955 fprintf(stderr, ntid > 1 956? "Process %u attached with %u threads\n" 957: "Process %u attached\n", 958 tcp->pid, ntid); 959 } 960 if (!(tcp->flags & TCB_ATTACHED)) { 961 /* -p PID, we failed to attach to PID itself 962 * but did attach to some of its sibling threads. 963 * Drop PID's tcp. 964 */ 965 droptcb(tcp); 966 } 967 continue; 968 } /* if (opendir worked) */ 969 } /* if (-f) */ 970 if (ptrace_attach_or_seize(tcp->pid) < 0) { 971 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 972 droptcb(tcp); 973 continue; 974 } 975 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 976 newoutf(tcp); 977 if (debug_flag) 978 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid); 979 980 if (daemonized_tracer) { 981 /* 982 * Make parent go away. 983 * Also makes grandparent's wait() unblock. 984 */ 985 kill(getppid(), SIGKILL); 986 } 987 988 if (!qflag) 989 fprintf(stderr, 990 "Process %u attached\n", 991 tcp->pid); 992 } /* for each tcbtab[] */ 993 994 ret: 995 if (interactive) 996 sigprocmask(SIG_SETMASK, &empty_set, NULL); 997} 998 999/* Stack-o-phobic exec helper, in the hope to work around 1000 * NOMMU + "daemonized tracer" difficulty. 1001 */ 1002struct exec_params { 1003 int fd_to_close; 1004 uid_t run_euid; 1005 gid_t run_egid; 1006 char **argv; 1007 char *pathname; 1008}; 1009static struct exec_params params_for_tracee; 1010static void __attribute__ ((noinline, noreturn)) 1011exec_or_die(void) 1012{ 1013 struct exec_params *params = ¶ms_for_tracee; 1014 1015 if (params->fd_to_close >= 0) 1016 close(params->fd_to_close); 1017 if (!daemonized_tracer && !use_seize) { 1018 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) { 1019 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)"); 1020 } 1021 } 1022 1023 if (username != NULL) { 1024 /* 1025 * It is important to set groups before we 1026 * lose privileges on setuid. 1027 */ 1028 if (initgroups(username, run_gid) < 0) { 1029 perror_msg_and_die("initgroups"); 1030 } 1031 if (setregid(run_gid, params->run_egid) < 0) { 1032 perror_msg_and_die("setregid"); 1033 } 1034 if (setreuid(run_uid, params->run_euid) < 0) { 1035 perror_msg_and_die("setreuid"); 1036 } 1037 } 1038 else if (geteuid() != 0) 1039 if (setreuid(run_uid, run_uid) < 0) { 1040 perror_msg_and_die("setreuid"); 1041 } 1042 1043 if (!daemonized_tracer) { 1044 /* 1045 * Induce a ptrace stop. Tracer (our parent) 1046 * will resume us with PTRACE_SYSCALL and display 1047 * the immediately following execve syscall. 1048 * Can't do this on NOMMU systems, we are after 1049 * vfork: parent is blocked, stopping would deadlock. 1050 */ 1051 if (!NOMMU_SYSTEM) 1052 kill(getpid(), SIGSTOP); 1053 } else { 1054 alarm(3); 1055 /* we depend on SIGCHLD set to SIG_DFL by init code */ 1056 /* if it happens to be SIG_IGN'ed, wait won't block */ 1057 wait(NULL); 1058 alarm(0); 1059 } 1060 1061 execv(params->pathname, params->argv); 1062 perror_msg_and_die("exec"); 1063} 1064 1065static void 1066startup_child(char **argv) 1067{ 1068 struct_stat statbuf; 1069 const char *filename; 1070 char pathname[MAXPATHLEN]; 1071 int pid; 1072 struct tcb *tcp; 1073 1074 filename = argv[0]; 1075 if (strchr(filename, '/')) { 1076 if (strlen(filename) > sizeof pathname - 1) { 1077 errno = ENAMETOOLONG; 1078 perror_msg_and_die("exec"); 1079 } 1080 strcpy(pathname, filename); 1081 } 1082#ifdef USE_DEBUGGING_EXEC 1083 /* 1084 * Debuggers customarily check the current directory 1085 * first regardless of the path but doing that gives 1086 * security geeks a panic attack. 1087 */ 1088 else if (stat_file(filename, &statbuf) == 0) 1089 strcpy(pathname, filename); 1090#endif /* USE_DEBUGGING_EXEC */ 1091 else { 1092 const char *path; 1093 int m, n, len; 1094 1095 for (path = getenv("PATH"); path && *path; path += m) { 1096 const char *colon = strchr(path, ':'); 1097 if (colon) { 1098 n = colon - path; 1099 m = n + 1; 1100 } 1101 else 1102 m = n = strlen(path); 1103 if (n == 0) { 1104 if (!getcwd(pathname, MAXPATHLEN)) 1105 continue; 1106 len = strlen(pathname); 1107 } 1108 else if (n > sizeof pathname - 1) 1109 continue; 1110 else { 1111 strncpy(pathname, path, n); 1112 len = n; 1113 } 1114 if (len && pathname[len - 1] != '/') 1115 pathname[len++] = '/'; 1116 strcpy(pathname + len, filename); 1117 if (stat_file(pathname, &statbuf) == 0 && 1118 /* Accept only regular files 1119 with some execute bits set. 1120 XXX not perfect, might still fail */ 1121 S_ISREG(statbuf.st_mode) && 1122 (statbuf.st_mode & 0111)) 1123 break; 1124 } 1125 } 1126 if (stat_file(pathname, &statbuf) < 0) { 1127 perror_msg_and_die("Can't stat '%s'", filename); 1128 } 1129 1130 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1; 1131 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid; 1132 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid; 1133 params_for_tracee.argv = argv; 1134 /* 1135 * On NOMMU, can be safely freed only after execve in tracee. 1136 * It's hard to know when that happens, so we just leak it. 1137 */ 1138 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname; 1139 1140#if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY 1141 if (daemonized_tracer) 1142 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY); 1143#endif 1144 1145 strace_child = pid = fork(); 1146 if (pid < 0) { 1147 perror_msg_and_die("fork"); 1148 } 1149 if ((pid != 0 && daemonized_tracer) 1150 || (pid == 0 && !daemonized_tracer) 1151 ) { 1152 /* We are to become the tracee. Two cases: 1153 * -D: we are parent 1154 * not -D: we are child 1155 */ 1156 exec_or_die(); 1157 } 1158 1159 /* We are the tracer */ 1160 1161 if (!daemonized_tracer) { 1162 if (!use_seize) { 1163 /* child did PTRACE_TRACEME, nothing to do in parent */ 1164 } else { 1165 if (!NOMMU_SYSTEM) { 1166 /* Wait until child stopped itself */ 1167 int status; 1168 while (waitpid(pid, &status, WSTOPPED) < 0) { 1169 if (errno == EINTR) 1170 continue; 1171 perror_msg_and_die("waitpid"); 1172 } 1173 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) { 1174 kill_save_errno(pid, SIGKILL); 1175 perror_msg_and_die("Unexpected wait status %x", status); 1176 } 1177 } 1178 /* Else: NOMMU case, we have no way to sync. 1179 * Just attach to it as soon as possible. 1180 * This means that we may miss a few first syscalls... 1181 */ 1182 1183 if (ptrace_attach_or_seize(pid)) { 1184 kill_save_errno(pid, SIGKILL); 1185 perror_msg_and_die("Can't attach to %d", pid); 1186 } 1187 if (!NOMMU_SYSTEM) 1188 kill(pid, SIGCONT); 1189 } 1190 tcp = alloctcb(pid); 1191 if (!NOMMU_SYSTEM) 1192 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP | post_attach_sigstop; 1193 else 1194 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP; 1195 newoutf(tcp); 1196 } 1197 else { 1198 /* With -D, we are *child* here, IOW: different pid. Fetch it: */ 1199 strace_tracer_pid = getpid(); 1200 /* The tracee is our parent: */ 1201 pid = getppid(); 1202 alloctcb(pid); 1203 /* attaching will be done later, by startup_attach */ 1204 /* note: we don't do newoutf(tcp) here either! */ 1205 1206 /* NOMMU BUG! -D mode is active, we (child) return, 1207 * and we will scribble over parent's stack! 1208 * When parent later unpauses, it segfaults. 1209 * 1210 * We work around it 1211 * (1) by declaring exec_or_die() NORETURN, 1212 * hopefully compiler will just jump to it 1213 * instead of call (won't push anything to stack), 1214 * (2) by trying very hard in exec_or_die() 1215 * to not use any stack, 1216 * (3) having a really big (MAXPATHLEN) stack object 1217 * in this function, which creates a "buffer" between 1218 * child's and parent's stack pointers. 1219 * This may save us if (1) and (2) failed 1220 * and compiler decided to use stack in exec_or_die() anyway 1221 * (happens on i386 because of stack parameter passing). 1222 * 1223 * A cleaner solution is to use makecontext + setcontext 1224 * to create a genuine separate stack and execute on it. 1225 */ 1226 } 1227} 1228 1229/* 1230 * Test whether the kernel support PTRACE_O_TRACECLONE et al options. 1231 * First fork a new child, call ptrace with PTRACE_SETOPTIONS on it, 1232 * and then see which options are supported by the kernel. 1233 */ 1234static int 1235test_ptrace_setoptions_followfork(void) 1236{ 1237 int pid, expected_grandchild = 0, found_grandchild = 0; 1238 const unsigned int test_options = PTRACE_O_TRACECLONE | 1239 PTRACE_O_TRACEFORK | 1240 PTRACE_O_TRACEVFORK; 1241 1242 /* Need fork for test. NOMMU has no forks */ 1243 if (NOMMU_SYSTEM) 1244 goto worked; /* be bold, and pretend that test succeeded */ 1245 1246 pid = fork(); 1247 if (pid < 0) 1248 perror_msg_and_die("fork"); 1249 if (pid == 0) { 1250 pid = getpid(); 1251 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1252 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1253 __func__); 1254 kill_save_errno(pid, SIGSTOP); 1255 if (fork() < 0) 1256 perror_msg_and_die("fork"); 1257 _exit(0); 1258 } 1259 1260 while (1) { 1261 int status, tracee_pid; 1262 1263 errno = 0; 1264 tracee_pid = wait(&status); 1265 if (tracee_pid <= 0) { 1266 if (errno == EINTR) 1267 continue; 1268 if (errno == ECHILD) 1269 break; 1270 kill_save_errno(pid, SIGKILL); 1271 perror_msg_and_die("%s: unexpected wait result %d", 1272 __func__, tracee_pid); 1273 } 1274 if (WIFEXITED(status)) { 1275 if (WEXITSTATUS(status)) { 1276 if (tracee_pid != pid) 1277 kill_save_errno(pid, SIGKILL); 1278 error_msg_and_die("%s: unexpected exit status %u", 1279 __func__, WEXITSTATUS(status)); 1280 } 1281 continue; 1282 } 1283 if (WIFSIGNALED(status)) { 1284 if (tracee_pid != pid) 1285 kill_save_errno(pid, SIGKILL); 1286 error_msg_and_die("%s: unexpected signal %u", 1287 __func__, WTERMSIG(status)); 1288 } 1289 if (!WIFSTOPPED(status)) { 1290 if (tracee_pid != pid) 1291 kill_save_errno(tracee_pid, SIGKILL); 1292 kill_save_errno(pid, SIGKILL); 1293 error_msg_and_die("%s: unexpected wait status %x", 1294 __func__, status); 1295 } 1296 if (tracee_pid != pid) { 1297 found_grandchild = tracee_pid; 1298 if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0) { 1299 kill_save_errno(tracee_pid, SIGKILL); 1300 kill_save_errno(pid, SIGKILL); 1301 perror_msg_and_die("PTRACE_CONT doesn't work"); 1302 } 1303 continue; 1304 } 1305 switch (WSTOPSIG(status)) { 1306 case SIGSTOP: 1307 if (ptrace(PTRACE_SETOPTIONS, pid, 0, test_options) < 0 1308 && errno != EINVAL && errno != EIO) 1309 perror_msg("PTRACE_SETOPTIONS"); 1310 break; 1311 case SIGTRAP: 1312 if (status >> 16 == PTRACE_EVENT_FORK) { 1313 long msg = 0; 1314 1315 if (ptrace(PTRACE_GETEVENTMSG, pid, 1316 NULL, (long) &msg) == 0) 1317 expected_grandchild = msg; 1318 } 1319 break; 1320 } 1321 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) { 1322 kill_save_errno(pid, SIGKILL); 1323 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1324 } 1325 } 1326 if (expected_grandchild && expected_grandchild == found_grandchild) { 1327 worked: 1328 ptrace_setoptions |= test_options; 1329 if (debug_flag) 1330 fprintf(stderr, "ptrace_setoptions = %#x\n", 1331 ptrace_setoptions); 1332 return 0; 1333 } 1334 error_msg("Test for PTRACE_O_TRACECLONE failed, " 1335 "giving up using this feature."); 1336 return 1; 1337} 1338 1339/* 1340 * Test whether the kernel support PTRACE_O_TRACESYSGOOD. 1341 * First fork a new child, call ptrace(PTRACE_SETOPTIONS) on it, 1342 * and then see whether it will stop with (SIGTRAP | 0x80). 1343 * 1344 * Use of this option enables correct handling of user-generated SIGTRAPs, 1345 * and SIGTRAPs generated by special instructions such as int3 on x86: 1346 * _start: .globl _start 1347 * int3 1348 * movl $42, %ebx 1349 * movl $1, %eax 1350 * int $0x80 1351 * (compile with: "gcc -nostartfiles -nostdlib -o int3 int3.S") 1352 */ 1353static int 1354test_ptrace_setoptions_for_all(void) 1355{ 1356 const unsigned int test_options = PTRACE_O_TRACESYSGOOD | 1357 PTRACE_O_TRACEEXEC; 1358 int pid; 1359 int it_worked = 0; 1360 1361 /* Need fork for test. NOMMU has no forks */ 1362 if (NOMMU_SYSTEM) 1363 goto worked; /* be bold, and pretend that test succeeded */ 1364 1365 pid = fork(); 1366 if (pid < 0) 1367 perror_msg_and_die("fork"); 1368 1369 if (pid == 0) { 1370 pid = getpid(); 1371 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1372 /* Note: exits with exitcode 1 */ 1373 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1374 __func__); 1375 kill(pid, SIGSTOP); 1376 _exit(0); /* parent should see entry into this syscall */ 1377 } 1378 1379 while (1) { 1380 int status, tracee_pid; 1381 1382 errno = 0; 1383 tracee_pid = wait(&status); 1384 if (tracee_pid <= 0) { 1385 if (errno == EINTR) 1386 continue; 1387 kill_save_errno(pid, SIGKILL); 1388 perror_msg_and_die("%s: unexpected wait result %d", 1389 __func__, tracee_pid); 1390 } 1391 if (WIFEXITED(status)) { 1392 if (WEXITSTATUS(status) == 0) 1393 break; 1394 error_msg_and_die("%s: unexpected exit status %u", 1395 __func__, WEXITSTATUS(status)); 1396 } 1397 if (WIFSIGNALED(status)) { 1398 error_msg_and_die("%s: unexpected signal %u", 1399 __func__, WTERMSIG(status)); 1400 } 1401 if (!WIFSTOPPED(status)) { 1402 kill(pid, SIGKILL); 1403 error_msg_and_die("%s: unexpected wait status %x", 1404 __func__, status); 1405 } 1406 if (WSTOPSIG(status) == SIGSTOP) { 1407 /* 1408 * We don't check "options aren't accepted" error. 1409 * If it happens, we'll never get (SIGTRAP | 0x80), 1410 * and thus will decide to not use the option. 1411 * IOW: the outcome of the test will be correct. 1412 */ 1413 if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0 1414 && errno != EINVAL && errno != EIO) 1415 perror_msg("PTRACE_SETOPTIONS"); 1416 } 1417 if (WSTOPSIG(status) == (SIGTRAP | 0x80)) { 1418 it_worked = 1; 1419 } 1420 if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) { 1421 kill_save_errno(pid, SIGKILL); 1422 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1423 } 1424 } 1425 1426 if (it_worked) { 1427 worked: 1428 syscall_trap_sig = (SIGTRAP | 0x80); 1429 ptrace_setoptions |= test_options; 1430 if (debug_flag) 1431 fprintf(stderr, "ptrace_setoptions = %#x\n", 1432 ptrace_setoptions); 1433 return 0; 1434 } 1435 1436 error_msg("Test for PTRACE_O_TRACESYSGOOD failed, " 1437 "giving up using this feature."); 1438 return 1; 1439} 1440 1441#if USE_SEIZE 1442static void 1443test_ptrace_seize(void) 1444{ 1445 int pid; 1446 1447 /* Need fork for test. NOMMU has no forks */ 1448 if (NOMMU_SYSTEM) { 1449 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1450 return; 1451 } 1452 1453 pid = fork(); 1454 if (pid < 0) 1455 perror_msg_and_die("fork"); 1456 1457 if (pid == 0) { 1458 pause(); 1459 _exit(0); 1460 } 1461 1462 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After 1463 * attaching tracee continues to run unless a trap condition occurs. 1464 * PTRACE_SEIZE doesn't affect signal or group stop state. 1465 */ 1466 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) { 1467 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1468 } else if (debug_flag) { 1469 fprintf(stderr, "PTRACE_SEIZE doesn't work\n"); 1470 } 1471 1472 kill(pid, SIGKILL); 1473 1474 while (1) { 1475 int status, tracee_pid; 1476 1477 errno = 0; 1478 tracee_pid = waitpid(pid, &status, 0); 1479 if (tracee_pid <= 0) { 1480 if (errno == EINTR) 1481 continue; 1482 perror_msg_and_die("%s: unexpected wait result %d", 1483 __func__, tracee_pid); 1484 } 1485 if (WIFSIGNALED(status)) { 1486 return; 1487 } 1488 error_msg_and_die("%s: unexpected wait status %x", 1489 __func__, status); 1490 } 1491} 1492#else /* !USE_SEIZE */ 1493# define test_ptrace_seize() ((void)0) 1494#endif 1495 1496static unsigned 1497get_os_release(void) 1498{ 1499 unsigned rel; 1500 const char *p; 1501 struct utsname u; 1502 if (uname(&u) < 0) 1503 perror_msg_and_die("uname"); 1504 /* u.release has this form: "3.2.9[-some-garbage]" */ 1505 rel = 0; 1506 p = u.release; 1507 for (;;) { 1508 if (!(*p >= '0' && *p <= '9')) 1509 error_msg_and_die("Bad OS release string: '%s'", u.release); 1510 /* Note: this open-codes KERNEL_VERSION(): */ 1511 rel = (rel << 8) | atoi(p); 1512 if (rel >= KERNEL_VERSION(1,0,0)) 1513 break; 1514 while (*p >= '0' && *p <= '9') 1515 p++; 1516 if (*p != '.') { 1517 if (rel >= KERNEL_VERSION(0,1,0)) { 1518 /* "X.Y-something" means "X.Y.0" */ 1519 rel <<= 8; 1520 break; 1521 } 1522 error_msg_and_die("Bad OS release string: '%s'", u.release); 1523 } 1524 p++; 1525 } 1526 return rel; 1527} 1528 1529/* 1530 * Initialization part of main() was eating much stack (~0.5k), 1531 * which was unused after init. 1532 * We can reuse it if we move init code into a separate function. 1533 * 1534 * Don't want main() to inline us and defeat the reason 1535 * we have a separate function. 1536 */ 1537static void __attribute__ ((noinline)) 1538init(int argc, char *argv[]) 1539{ 1540 struct tcb *tcp; 1541 int c, i; 1542 int optF = 0; 1543 struct sigaction sa; 1544 1545 progname = argv[0] ? argv[0] : "strace"; 1546 1547 /* Make sure SIGCHLD has the default action so that waitpid 1548 definitely works without losing track of children. The user 1549 should not have given us a bogus state to inherit, but he might 1550 have. Arguably we should detect SIG_IGN here and pass it on 1551 to children, but probably noone really needs that. */ 1552 signal(SIGCHLD, SIG_DFL); 1553 1554 strace_tracer_pid = getpid(); 1555 1556 os_release = get_os_release(); 1557 1558 /* Allocate the initial tcbtab. */ 1559 tcbtabsize = argc; /* Surely enough for all -p args. */ 1560 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0])); 1561 if (!tcbtab) 1562 die_out_of_memory(); 1563 tcp = calloc(tcbtabsize, sizeof(*tcp)); 1564 if (!tcp) 1565 die_out_of_memory(); 1566 for (c = 0; c < tcbtabsize; c++) 1567 tcbtab[c] = tcp++; 1568 1569 shared_log = stderr; 1570 set_sortby(DEFAULT_SORTBY); 1571 set_personality(DEFAULT_PERSONALITY); 1572 qualify("trace=all"); 1573 qualify("abbrev=all"); 1574 qualify("verbose=all"); 1575#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE) 1576# error Bug in DEFAULT_QUAL_FLAGS 1577#endif 1578 qualify("signal=all"); 1579 while ((c = getopt(argc, argv, 1580 "+b:cCdfFhiqrtTvVxyz" 1581 "D" 1582 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) { 1583 switch (c) { 1584 case 'b': 1585 if (strcmp(optarg, "execve") != 0) 1586 error_msg_and_die("Syscall '%s' for -b isn't supported", 1587 optarg); 1588 detach_on_execve = 1; 1589 break; 1590 case 'c': 1591 if (cflag == CFLAG_BOTH) { 1592 error_msg_and_die("-c and -C are mutually exclusive"); 1593 } 1594 cflag = CFLAG_ONLY_STATS; 1595 break; 1596 case 'C': 1597 if (cflag == CFLAG_ONLY_STATS) { 1598 error_msg_and_die("-c and -C are mutually exclusive"); 1599 } 1600 cflag = CFLAG_BOTH; 1601 break; 1602 case 'd': 1603 debug_flag = 1; 1604 break; 1605 case 'D': 1606 daemonized_tracer = 1; 1607 break; 1608 case 'F': 1609 optF = 1; 1610 break; 1611 case 'f': 1612 followfork++; 1613 break; 1614 case 'h': 1615 usage(stdout, 0); 1616 break; 1617 case 'i': 1618 iflag = 1; 1619 break; 1620 case 'q': 1621 qflag++; 1622 break; 1623 case 'r': 1624 rflag = 1; 1625 /* fall through to tflag++ */ 1626 case 't': 1627 tflag++; 1628 break; 1629 case 'T': 1630 Tflag = 1; 1631 break; 1632 case 'x': 1633 xflag++; 1634 break; 1635 case 'y': 1636 show_fd_path = 1; 1637 break; 1638 case 'v': 1639 qualify("abbrev=none"); 1640 break; 1641 case 'V': 1642 printf("%s -- version %s\n", PACKAGE_NAME, VERSION); 1643 exit(0); 1644 break; 1645 case 'z': 1646 not_failing_only = 1; 1647 break; 1648 case 'a': 1649 acolumn = string_to_uint(optarg); 1650 if (acolumn < 0) 1651 error_opt_arg(c, optarg); 1652 break; 1653 case 'e': 1654 qualify(optarg); 1655 break; 1656 case 'o': 1657 outfname = strdup(optarg); 1658 break; 1659 case 'O': 1660 i = string_to_uint(optarg); 1661 if (i < 0) 1662 error_opt_arg(c, optarg); 1663 set_overhead(i); 1664 break; 1665 case 'p': 1666 process_opt_p_list(optarg); 1667 break; 1668 case 'P': 1669 pathtrace_select(optarg); 1670 break; 1671 case 's': 1672 i = string_to_uint(optarg); 1673 if (i < 0) 1674 error_opt_arg(c, optarg); 1675 max_strlen = i; 1676 break; 1677 case 'S': 1678 set_sortby(optarg); 1679 break; 1680 case 'u': 1681 username = strdup(optarg); 1682 break; 1683 case 'E': 1684 if (putenv(optarg) < 0) 1685 die_out_of_memory(); 1686 break; 1687 case 'I': 1688 opt_intr = string_to_uint(optarg); 1689 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS) 1690 error_opt_arg(c, optarg); 1691 break; 1692 default: 1693 usage(stderr, 1); 1694 break; 1695 } 1696 } 1697 argv += optind; 1698 /* argc -= optind; - no need, argc is not used below */ 1699 1700 acolumn_spaces = malloc(acolumn + 1); 1701 if (!acolumn_spaces) 1702 die_out_of_memory(); 1703 memset(acolumn_spaces, ' ', acolumn); 1704 acolumn_spaces[acolumn] = '\0'; 1705 1706 /* Must have PROG [ARGS], or -p PID. Not both. */ 1707 if (!argv[0] == !nprocs) 1708 usage(stderr, 1); 1709 1710 if (nprocs != 0 && daemonized_tracer) { 1711 error_msg_and_die("-D and -p are mutually exclusive"); 1712 } 1713 1714 if (!followfork) 1715 followfork = optF; 1716 1717 if (followfork >= 2 && cflag) { 1718 error_msg_and_die("(-c or -C) and -ff are mutually exclusive"); 1719 } 1720 1721 /* See if they want to run as another user. */ 1722 if (username != NULL) { 1723 struct passwd *pent; 1724 1725 if (getuid() != 0 || geteuid() != 0) { 1726 error_msg_and_die("You must be root to use the -u option"); 1727 } 1728 pent = getpwnam(username); 1729 if (pent == NULL) { 1730 error_msg_and_die("Cannot find user '%s'", username); 1731 } 1732 run_uid = pent->pw_uid; 1733 run_gid = pent->pw_gid; 1734 } 1735 else { 1736 run_uid = getuid(); 1737 run_gid = getgid(); 1738 } 1739 1740 /* 1741 * On any reasonably recent Linux kernel (circa about 2.5.46) 1742 * need_fork_exec_workarounds should stay 0 after these tests: 1743 */ 1744 /*need_fork_exec_workarounds = 0; - already is */ 1745 if (followfork) 1746 need_fork_exec_workarounds = test_ptrace_setoptions_followfork(); 1747 need_fork_exec_workarounds |= test_ptrace_setoptions_for_all(); 1748 test_ptrace_seize(); 1749 1750 /* Check if they want to redirect the output. */ 1751 if (outfname) { 1752 /* See if they want to pipe the output. */ 1753 if (outfname[0] == '|' || outfname[0] == '!') { 1754 /* 1755 * We can't do the <outfname>.PID funny business 1756 * when using popen, so prohibit it. 1757 */ 1758 if (followfork >= 2) 1759 error_msg_and_die("Piping the output and -ff are mutually exclusive"); 1760 shared_log = strace_popen(outfname + 1); 1761 } 1762 else if (followfork < 2) 1763 shared_log = strace_fopen(outfname); 1764 } else { 1765 /* -ff without -o FILE is the same as single -f */ 1766 if (followfork >= 2) 1767 followfork = 1; 1768 } 1769 1770 if (!outfname || outfname[0] == '|' || outfname[0] == '!') { 1771 char *buf = malloc(BUFSIZ); 1772 if (!buf) 1773 die_out_of_memory(); 1774 setvbuf(shared_log, buf, _IOLBF, BUFSIZ); 1775 } 1776 if (outfname && argv[0]) { 1777 if (!opt_intr) 1778 opt_intr = INTR_NEVER; 1779 qflag = 1; 1780 } 1781 if (!opt_intr) 1782 opt_intr = INTR_WHILE_WAIT; 1783 1784 /* argv[0] -pPID -oFILE Default interactive setting 1785 * yes 0 0 INTR_WHILE_WAIT 1786 * no 1 0 INTR_WHILE_WAIT 1787 * yes 0 1 INTR_NEVER 1788 * no 1 1 INTR_WHILE_WAIT 1789 */ 1790 1791 sigemptyset(&empty_set); 1792 sigemptyset(&blocked_set); 1793 1794 /* startup_child() must be called before the signal handlers get 1795 * installed below as they are inherited into the spawned process. 1796 * Also we do not need to be protected by them as during interruption 1797 * in the startup_child() mode we kill the spawned process anyway. 1798 */ 1799 if (argv[0]) { 1800 if (!NOMMU_SYSTEM || daemonized_tracer) 1801 hide_log_until_execve = 1; 1802 skip_one_b_execve = 1; 1803 startup_child(argv); 1804 } 1805 1806 sa.sa_handler = SIG_IGN; 1807 sigemptyset(&sa.sa_mask); 1808 sa.sa_flags = 0; 1809 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */ 1810 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */ 1811 if (opt_intr != INTR_ANYWHERE) { 1812 if (opt_intr == INTR_BLOCK_TSTP_TOO) 1813 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */ 1814 /* 1815 * In interactive mode (if no -o OUTFILE, or -p PID is used), 1816 * fatal signals are blocked while syscall stop is processed, 1817 * and acted on in between, when waiting for new syscall stops. 1818 * In non-interactive mode, signals are ignored. 1819 */ 1820 if (opt_intr == INTR_WHILE_WAIT) { 1821 sigaddset(&blocked_set, SIGHUP); 1822 sigaddset(&blocked_set, SIGINT); 1823 sigaddset(&blocked_set, SIGQUIT); 1824 sigaddset(&blocked_set, SIGPIPE); 1825 sigaddset(&blocked_set, SIGTERM); 1826 sa.sa_handler = interrupt; 1827 } 1828 /* SIG_IGN, or set handler for these */ 1829 sigaction(SIGHUP, &sa, NULL); 1830 sigaction(SIGINT, &sa, NULL); 1831 sigaction(SIGQUIT, &sa, NULL); 1832 sigaction(SIGPIPE, &sa, NULL); 1833 sigaction(SIGTERM, &sa, NULL); 1834 } 1835 if (nprocs != 0 || daemonized_tracer) 1836 startup_attach(); 1837 1838 /* Do we want pids printed in our -o OUTFILE? 1839 * -ff: no (every pid has its own file); or 1840 * -f: yes (there can be more pids in the future); or 1841 * -p PID1,PID2: yes (there are already more than one pid) 1842 */ 1843 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1)); 1844} 1845 1846static struct tcb * 1847pid2tcb(int pid) 1848{ 1849 int i; 1850 1851 if (pid <= 0) 1852 return NULL; 1853 1854 for (i = 0; i < tcbtabsize; i++) { 1855 struct tcb *tcp = tcbtab[i]; 1856 if (tcp->pid == pid && (tcp->flags & TCB_INUSE)) 1857 return tcp; 1858 } 1859 1860 return NULL; 1861} 1862 1863static void 1864cleanup(void) 1865{ 1866 int i; 1867 struct tcb *tcp; 1868 int fatal_sig; 1869 1870 /* 'interrupted' is a volatile object, fetch it only once */ 1871 fatal_sig = interrupted; 1872 if (!fatal_sig) 1873 fatal_sig = SIGTERM; 1874 1875 for (i = 0; i < tcbtabsize; i++) { 1876 tcp = tcbtab[i]; 1877 if (!(tcp->flags & TCB_INUSE)) 1878 continue; 1879 if (debug_flag) 1880 fprintf(stderr, 1881 "cleanup: looking at pid %u\n", tcp->pid); 1882 if (tcp->flags & TCB_STRACE_CHILD) { 1883 kill(tcp->pid, SIGCONT); 1884 kill(tcp->pid, fatal_sig); 1885 } 1886 detach(tcp); 1887 } 1888 if (cflag) 1889 call_summary(shared_log); 1890} 1891 1892static void 1893interrupt(int sig) 1894{ 1895 interrupted = sig; 1896} 1897 1898static int 1899trace(void) 1900{ 1901 struct rusage ru; 1902 struct rusage *rup = cflag ? &ru : NULL; 1903#ifdef __WALL 1904 static int wait4_options = __WALL; 1905#endif 1906 1907 while (nprocs != 0) { 1908 int pid; 1909 int wait_errno; 1910 int status, sig; 1911 int stopped; 1912 struct tcb *tcp; 1913 unsigned event; 1914 1915 if (interrupted) 1916 return 0; 1917 if (interactive) 1918 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1919#ifdef __WALL 1920 pid = wait4(-1, &status, wait4_options, rup); 1921 if (pid < 0 && (wait4_options & __WALL) && errno == EINVAL) { 1922 /* this kernel does not support __WALL */ 1923 wait4_options &= ~__WALL; 1924 pid = wait4(-1, &status, wait4_options, rup); 1925 } 1926 if (pid < 0 && !(wait4_options & __WALL) && errno == ECHILD) { 1927 /* most likely a "cloned" process */ 1928 pid = wait4(-1, &status, __WCLONE, rup); 1929 if (pid < 0) { 1930 perror_msg("wait4(__WCLONE) failed"); 1931 } 1932 } 1933#else 1934 pid = wait4(-1, &status, 0, rup); 1935#endif /* __WALL */ 1936 wait_errno = errno; 1937 if (interactive) 1938 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1939 1940 if (pid < 0) { 1941 switch (wait_errno) { 1942 case EINTR: 1943 continue; 1944 case ECHILD: 1945 /* 1946 * We would like to verify this case 1947 * but sometimes a race in Solbourne's 1948 * version of SunOS sometimes reports 1949 * ECHILD before sending us SIGCHILD. 1950 */ 1951 return 0; 1952 default: 1953 errno = wait_errno; 1954 perror_msg("wait"); 1955 return -1; 1956 } 1957 } 1958 if (pid == popen_pid) { 1959 if (WIFEXITED(status) || WIFSIGNALED(status)) 1960 popen_pid = 0; 1961 continue; 1962 } 1963 1964 event = ((unsigned)status >> 16); 1965 if (debug_flag) { 1966 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16]; 1967 char evbuf[sizeof(",PTRACE_EVENT_?? (%u)") + sizeof(int)*3 /*paranoia:*/ + 16]; 1968 strcpy(buf, "???"); 1969 if (WIFSIGNALED(status)) 1970#ifdef WCOREDUMP 1971 sprintf(buf, "WIFSIGNALED,%ssig=%s", 1972 WCOREDUMP(status) ? "core," : "", 1973 signame(WTERMSIG(status))); 1974#else 1975 sprintf(buf, "WIFSIGNALED,sig=%s", 1976 signame(WTERMSIG(status))); 1977#endif 1978 if (WIFEXITED(status)) 1979 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status)); 1980 if (WIFSTOPPED(status)) 1981 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status))); 1982#ifdef WIFCONTINUED 1983 if (WIFCONTINUED(status)) 1984 strcpy(buf, "WIFCONTINUED"); 1985#endif 1986 evbuf[0] = '\0'; 1987 if (event != 0) { 1988 static const char *const event_names[] = { 1989 [PTRACE_EVENT_CLONE] = "CLONE", 1990 [PTRACE_EVENT_FORK] = "FORK", 1991 [PTRACE_EVENT_VFORK] = "VFORK", 1992 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE", 1993 [PTRACE_EVENT_EXEC] = "EXEC", 1994 [PTRACE_EVENT_EXIT] = "EXIT", 1995 }; 1996 const char *e; 1997 if (event < ARRAY_SIZE(event_names)) 1998 e = event_names[event]; 1999 else { 2000 sprintf(buf, "?? (%u)", event); 2001 e = buf; 2002 } 2003 sprintf(evbuf, ",PTRACE_EVENT_%s", e); 2004 } 2005 fprintf(stderr, " [wait(0x%04x) = %u] %s%s\n", status, pid, buf, evbuf); 2006 } 2007 2008 /* Look up 'pid' in our table. */ 2009 tcp = pid2tcb(pid); 2010 2011 if (!tcp) { 2012 if (followfork) { 2013 tcp = alloctcb(pid); 2014 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 2015 newoutf(tcp); 2016 if (!qflag) 2017 fprintf(stderr, "Process %d attached\n", 2018 pid); 2019 } else { 2020 /* This can happen if a clone call used 2021 CLONE_PTRACE itself. */ 2022 if (WIFSTOPPED(status)) 2023 ptrace(PTRACE_CONT, pid, (char *) 0, 0); 2024 error_msg_and_die("Unknown pid: %u", pid); 2025 } 2026 } 2027 2028 clear_regs(); 2029 if (WIFSTOPPED(status)) 2030 get_regs(pid); 2031 2032 /* Under Linux, execve changes pid to thread leader's pid, 2033 * and we see this changed pid on EVENT_EXEC and later, 2034 * execve sysexit. Leader "disappears" without exit 2035 * notification. Let user know that, drop leader's tcb, 2036 * and fix up pid in execve thread's tcb. 2037 * Effectively, execve thread's tcb replaces leader's tcb. 2038 * 2039 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED 2040 * on exit syscall) in multithreaded programs exactly 2041 * in order to handle this case. 2042 * 2043 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0. 2044 * On 2.6 and earlier, it can return garbage. 2045 */ 2046 if (event == PTRACE_EVENT_EXEC && os_release >= KERNEL_VERSION(3,0,0)) { 2047 FILE *fp; 2048 struct tcb *execve_thread; 2049 long old_pid = 0; 2050 2051 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0) 2052 goto dont_switch_tcbs; 2053 if (old_pid <= 0 || old_pid == pid) 2054 goto dont_switch_tcbs; 2055 execve_thread = pid2tcb(old_pid); 2056 /* It should be !NULL, but I feel paranoid */ 2057 if (!execve_thread) 2058 goto dont_switch_tcbs; 2059 2060 if (execve_thread->curcol != 0) { 2061 /* 2062 * One case we are here is -ff: 2063 * try "strace -oLOG -ff test/threaded_execve" 2064 */ 2065 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid); 2066 /*execve_thread->curcol = 0; - no need, see code below */ 2067 } 2068 /* Swap output FILEs (needed for -ff) */ 2069 fp = execve_thread->outf; 2070 execve_thread->outf = tcp->outf; 2071 tcp->outf = fp; 2072 /* And their column positions */ 2073 execve_thread->curcol = tcp->curcol; 2074 tcp->curcol = 0; 2075 /* Drop leader, but close execve'd thread outfile (if -ff) */ 2076 droptcb(tcp); 2077 /* Switch to the thread, reusing leader's outfile and pid */ 2078 tcp = execve_thread; 2079 tcp->pid = pid; 2080 if (cflag != CFLAG_ONLY_STATS) { 2081 printleader(tcp); 2082 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid); 2083 line_ended(); 2084 tcp->flags |= TCB_REPRINT; 2085 } 2086 } 2087 dont_switch_tcbs: 2088 2089 if (event == PTRACE_EVENT_EXEC) { 2090 if (detach_on_execve && !skip_one_b_execve) 2091 detach(tcp); /* do "-b execve" thingy */ 2092 skip_one_b_execve = 0; 2093 } 2094 2095 /* Set current output file */ 2096 current_tcp = tcp; 2097 2098 if (cflag) { 2099 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime); 2100 tcp->stime = ru.ru_stime; 2101 } 2102 2103 if (WIFSIGNALED(status)) { 2104 if (pid == strace_child) 2105 exit_code = 0x100 | WTERMSIG(status); 2106 if (cflag != CFLAG_ONLY_STATS 2107 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL) 2108 ) { 2109 printleader(tcp); 2110#ifdef WCOREDUMP 2111 tprintf("+++ killed by %s %s+++\n", 2112 signame(WTERMSIG(status)), 2113 WCOREDUMP(status) ? "(core dumped) " : ""); 2114#else 2115 tprintf("+++ killed by %s +++\n", 2116 signame(WTERMSIG(status))); 2117#endif 2118 line_ended(); 2119 } 2120 droptcb(tcp); 2121 continue; 2122 } 2123 if (WIFEXITED(status)) { 2124 if (pid == strace_child) 2125 exit_code = WEXITSTATUS(status); 2126 if (cflag != CFLAG_ONLY_STATS && 2127 qflag < 2) { 2128 printleader(tcp); 2129 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status)); 2130 line_ended(); 2131 } 2132 droptcb(tcp); 2133 continue; 2134 } 2135 if (!WIFSTOPPED(status)) { 2136 fprintf(stderr, "PANIC: pid %u not stopped\n", pid); 2137 droptcb(tcp); 2138 continue; 2139 } 2140 2141 /* Is this the very first time we see this tracee stopped? */ 2142 if (tcp->flags & TCB_STARTUP) { 2143 if (debug_flag) 2144 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n", tcp->pid); 2145 tcp->flags &= ~TCB_STARTUP; 2146 if (tcp->flags & TCB_BPTSET) { 2147 /* 2148 * One example is a breakpoint inherited from 2149 * parent through fork(). 2150 */ 2151 if (clearbpt(tcp) < 0) { 2152 /* Pretty fatal */ 2153 droptcb(tcp); 2154 cleanup(); 2155 return -1; 2156 } 2157 } 2158 if (ptrace_setoptions) { 2159 if (debug_flag) 2160 fprintf(stderr, "setting opts %x on pid %d\n", ptrace_setoptions, tcp->pid); 2161 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) { 2162 if (errno != ESRCH) { 2163 /* Should never happen, really */ 2164 perror_msg_and_die("PTRACE_SETOPTIONS"); 2165 } 2166 } 2167 } 2168 } 2169 2170 sig = WSTOPSIG(status); 2171 2172 if (event != 0) { 2173 /* Ptrace event */ 2174#if USE_SEIZE 2175 if (event == PTRACE_EVENT_STOP) { 2176 /* 2177 * PTRACE_INTERRUPT-stop or group-stop. 2178 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here. 2179 */ 2180 if (sig == SIGSTOP 2181 || sig == SIGTSTP 2182 || sig == SIGTTIN 2183 || sig == SIGTTOU 2184 ) { 2185 stopped = 1; 2186 goto show_stopsig; 2187 } 2188 } 2189#endif 2190 goto restart_tracee_with_sig_0; 2191 } 2192 2193 /* Is this post-attach SIGSTOP? 2194 * Interestingly, the process may stop 2195 * with STOPSIG equal to some other signal 2196 * than SIGSTOP if we happend to attach 2197 * just before the process takes a signal. 2198 */ 2199 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) { 2200 if (debug_flag) 2201 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid); 2202 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP; 2203 goto restart_tracee_with_sig_0; 2204 } 2205 2206 if (sig != syscall_trap_sig) { 2207 siginfo_t si; 2208 2209 /* Nonzero (true) if tracee is stopped by signal 2210 * (as opposed to "tracee received signal"). 2211 * TODO: shouldn't we check for errno == EINVAL too? 2212 * We can get ESRCH instead, you know... 2213 */ 2214 stopped = (ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0); 2215#if USE_SEIZE 2216 show_stopsig: 2217#endif 2218 if (cflag != CFLAG_ONLY_STATS 2219 && !hide_log_until_execve 2220 && (qual_flags[sig] & QUAL_SIGNAL) 2221 ) { 2222#if defined(PT_CR_IPSR) && defined(PT_CR_IIP) 2223 long pc = 0; 2224 long psr = 0; 2225 2226 upeek(tcp, PT_CR_IPSR, &psr); 2227 upeek(tcp, PT_CR_IIP, &pc); 2228 2229# define PSR_RI 41 2230 pc += (psr >> PSR_RI) & 0x3; 2231# define PC_FORMAT_STR " @ %lx" 2232# define PC_FORMAT_ARG , pc 2233#else 2234# define PC_FORMAT_STR "" 2235# define PC_FORMAT_ARG /* nothing */ 2236#endif 2237 printleader(tcp); 2238 if (!stopped) { 2239 tprintf("--- %s ", signame(sig)); 2240 printsiginfo(&si, verbose(tcp)); 2241 tprintf(PC_FORMAT_STR " ---\n" 2242 PC_FORMAT_ARG); 2243 } else 2244 tprintf("--- stopped by %s" PC_FORMAT_STR " ---\n", 2245 signame(sig) 2246 PC_FORMAT_ARG); 2247 line_ended(); 2248 } 2249 2250 if (!stopped) 2251 /* It's signal-delivery-stop. Inject the signal */ 2252 goto restart_tracee; 2253 2254 /* It's group-stop */ 2255 if (use_seize) { 2256 /* 2257 * This ends ptrace-stop, but does *not* end group-stop. 2258 * This makes stopping signals work properly on straced process 2259 * (that is, process really stops. It used to continue to run). 2260 */ 2261 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) { 2262 cleanup(); 2263 return -1; 2264 } 2265 continue; 2266 } 2267 /* We don't have PTRACE_LISTEN support... */ 2268 goto restart_tracee; 2269 } 2270 2271 /* We handled quick cases, we are permitted to interrupt now. */ 2272 if (interrupted) 2273 return 0; 2274 2275 /* This should be syscall entry or exit. 2276 * (Or it still can be that pesky post-execve SIGTRAP!) 2277 * Handle it. 2278 */ 2279 if (trace_syscall(tcp) < 0) { 2280 /* ptrace() failed in trace_syscall(). 2281 * Likely a result of process disappearing mid-flight. 2282 * Observed case: exit_group() or SIGKILL terminating 2283 * all processes in thread group. 2284 * We assume that ptrace error was caused by process death. 2285 * We used to detach(tcp) here, but since we no longer 2286 * implement "detach before death" policy/hack, 2287 * we can let this process to report its death to us 2288 * normally, via WIFEXITED or WIFSIGNALED wait status. 2289 */ 2290 continue; 2291 } 2292 restart_tracee_with_sig_0: 2293 sig = 0; 2294 restart_tracee: 2295 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) { 2296 cleanup(); 2297 return -1; 2298 } 2299 } 2300 return 0; 2301} 2302 2303int 2304main(int argc, char *argv[]) 2305{ 2306 init(argc, argv); 2307 2308 /* Run main tracing loop */ 2309 if (trace() < 0) 2310 return 1; 2311 2312 cleanup(); 2313 fflush(NULL); 2314 if (shared_log != stderr) 2315 fclose(shared_log); 2316 if (popen_pid) { 2317 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR) 2318 ; 2319 } 2320 if (exit_code > 0xff) { 2321 /* Avoid potential core file clobbering. */ 2322 struct_rlimit rlim = {0, 0}; 2323 set_rlimit(RLIMIT_CORE, &rlim); 2324 2325 /* Child was killed by a signal, mimic that. */ 2326 exit_code &= 0xff; 2327 signal(exit_code, SIG_DFL); 2328 raise(exit_code); 2329 /* Paranoia - what if this signal is not fatal? 2330 Exit with 128 + signo then. */ 2331 exit_code += 128; 2332 } 2333 2334 return exit_code; 2335} 2336