strace.c revision 725dd425a60af0cd0fa7bb764ae3a122269a70fc
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, interrupt_done; 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 interrupt_done = 0; 754 if (tcp->flags & TCB_ATTACHED) { 755 /* 756 * We attached but possibly didn't see the expected SIGSTOP. 757 * We must catch exactly one as otherwise the detached process 758 * would be left stopped (process state T). 759 */ 760 sigstop_expected = (tcp->flags & TCB_IGNORE_ONE_SIGSTOP); 761 error = ptrace(PTRACE_DETACH, tcp->pid, 0, 0); 762 if (error == 0) { 763 /* On a clear day, you can see forever. */ 764 } 765 else if (errno != ESRCH) { 766 /* Shouldn't happen. */ 767 perror_msg("detach: ptrace(PTRACE_DETACH, ...)"); 768 } 769 else 770 /* ESRCH: process is either not stopped or doesn't exist. */ 771 if (my_tkill(tcp->pid, 0) < 0) { 772 if (errno != ESRCH) 773 /* Shouldn't happen. */ 774 perror_msg("detach: checking sanity"); 775 /* else: process doesn't exist. */ 776 } 777 else 778 /* Process is not stopped. */ 779 if (!sigstop_expected) { 780 /* We need to stop it. */ 781 if (use_seize) { 782 /* 783 * With SEIZE, tracee can be in group-stop already. 784 * In this state sending it another SIGSTOP does nothing. 785 * Need to use INTERRUPT. 786 * Testcase: trying to ^C a "strace -p <stopped_process>". 787 */ 788 error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0); 789 if (!error) 790 interrupt_done = 1; 791 } 792 else { 793 error = my_tkill(tcp->pid, SIGSTOP); 794 if (!error) 795 sigstop_expected = 1; 796 } 797 if (error && errno != ESRCH) { 798 if (use_seize) 799 perror_msg("detach: ptrace(PTRACE_INTERRUPT, ...)"); 800 else 801 perror_msg("detach: stopping child"); 802 } 803 } 804 } 805 806 if (sigstop_expected || interrupt_done) { 807 for (;;) { 808 int sig; 809 if (waitpid(tcp->pid, &status, __WALL) < 0) { 810 if (errno == EINTR) 811 continue; 812 if (errno == ECHILD) /* Already gone. */ 813 break; 814 perror_msg("detach: waiting"); 815 break; 816 } 817 if (!WIFSTOPPED(status)) { 818 /* Au revoir, mon ami. */ 819 break; 820 } 821 sig = WSTOPSIG(status); 822 if (debug_flag) 823 fprintf(stderr, "detach wait: event:%d sig:%d\n", 824 (unsigned)status >> 16, sig); 825 if (sigstop_expected && sig == SIGSTOP) { 826 /* Detach, suppressing SIGSTOP */ 827 ptrace_restart(PTRACE_DETACH, tcp, 0); 828 break; 829 } 830 if (interrupt_done) { 831 unsigned event = (unsigned)status >> 16; 832 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) { 833 /* 834 * sig == SIGTRAP: PTRACE_INTERRUPT stop. 835 * sig == other: process was already stopped 836 * with this stopping sig (see tests/detach-stopped). 837 * Looks like re-injecting this sig is not necessary 838 * in DETACH for the tracee to remain stopped. 839 */ 840 sig = 0; 841 } 842 /* 843 * PTRACE_INTERRUPT is not guaranteed to produce 844 * the above event if other ptrace-stop is pending. 845 * See tests/detach-sleeping testcase: 846 * strace got SIGINT while tracee is sleeping. 847 * We sent PTRACE_INTERRUPT. 848 * We see syscall exit, not PTRACE_INTERRUPT stop. 849 * We won't get PTRACE_INTERRUPT stop 850 * if we would CONT now. Need to DETACH. 851 */ 852 if (sig == syscall_trap_sig) 853 sig = 0; 854 /* else: not sure in which case we can be here. 855 * Signal stop? Inject it while detaching. 856 */ 857 ptrace_restart(PTRACE_DETACH, tcp, sig); 858 break; 859 } 860 if (sig == syscall_trap_sig) 861 sig = 0; 862 /* Can't detach just yet, may need to wait for SIGSTOP */ 863 error = ptrace_restart(PTRACE_CONT, tcp, sig); 864 if (error < 0) 865 break; 866 } 867 } 868 869 if (!qflag && (tcp->flags & TCB_ATTACHED)) 870 fprintf(stderr, "Process %u detached\n", tcp->pid); 871 872 droptcb(tcp); 873 874 return error; 875} 876 877static void 878process_opt_p_list(char *opt) 879{ 880 while (*opt) { 881 /* 882 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`". 883 * pidof uses space as delim, pgrep uses newline. :( 884 */ 885 int pid; 886 char *delim = opt + strcspn(opt, ", \n\t"); 887 char c = *delim; 888 889 *delim = '\0'; 890 pid = string_to_uint(opt); 891 if (pid <= 0) { 892 error_msg_and_die("Invalid process id: '%s'", opt); 893 } 894 if (pid == strace_tracer_pid) { 895 error_msg_and_die("I'm sorry, I can't let you do that, Dave."); 896 } 897 *delim = c; 898 alloctcb(pid); 899 if (c == '\0') 900 break; 901 opt = delim + 1; 902 } 903} 904 905static void 906startup_attach(void) 907{ 908 int tcbi; 909 struct tcb *tcp; 910 911 /* 912 * Block user interruptions as we would leave the traced 913 * process stopped (process state T) if we would terminate in 914 * between PTRACE_ATTACH and wait4() on SIGSTOP. 915 * We rely on cleanup() from this point on. 916 */ 917 if (interactive) 918 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 919 920 if (daemonized_tracer) { 921 pid_t pid = fork(); 922 if (pid < 0) { 923 perror_msg_and_die("fork"); 924 } 925 if (pid) { /* parent */ 926 /* 927 * Wait for grandchild to attach to straced process 928 * (grandparent). Grandchild SIGKILLs us after it attached. 929 * Grandparent's wait() is unblocked by our death, 930 * it proceeds to exec the straced program. 931 */ 932 pause(); 933 _exit(0); /* paranoia */ 934 } 935 /* grandchild */ 936 /* We will be the tracer process. Remember our new pid: */ 937 strace_tracer_pid = getpid(); 938 } 939 940 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) { 941 tcp = tcbtab[tcbi]; 942 943 if (!(tcp->flags & TCB_INUSE)) 944 continue; 945 946 /* Is this a process we should attach to, but not yet attached? */ 947 if (tcp->flags & TCB_ATTACHED) 948 continue; /* no, we already attached it */ 949 950 if (followfork && !daemonized_tracer) { 951 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3]; 952 DIR *dir; 953 954 sprintf(procdir, "/proc/%d/task", tcp->pid); 955 dir = opendir(procdir); 956 if (dir != NULL) { 957 unsigned int ntid = 0, nerr = 0; 958 struct_dirent *de; 959 960 while ((de = read_dir(dir)) != NULL) { 961 struct tcb *cur_tcp; 962 int tid; 963 964 if (de->d_fileno == 0) 965 continue; 966 /* we trust /proc filesystem */ 967 tid = atoi(de->d_name); 968 if (tid <= 0) 969 continue; 970 ++ntid; 971 if (ptrace_attach_or_seize(tid) < 0) { 972 ++nerr; 973 if (debug_flag) 974 fprintf(stderr, "attach to pid %d failed\n", tid); 975 continue; 976 } 977 if (debug_flag) 978 fprintf(stderr, "attach to pid %d succeeded\n", tid); 979 cur_tcp = tcp; 980 if (tid != tcp->pid) 981 cur_tcp = alloctcb(tid); 982 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 983 newoutf(cur_tcp); 984 } 985 closedir(dir); 986 if (interactive) { 987 sigprocmask(SIG_SETMASK, &empty_set, NULL); 988 if (interrupted) 989 goto ret; 990 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 991 } 992 ntid -= nerr; 993 if (ntid == 0) { 994 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 995 droptcb(tcp); 996 continue; 997 } 998 if (!qflag) { 999 fprintf(stderr, ntid > 1 1000? "Process %u attached with %u threads\n" 1001: "Process %u attached\n", 1002 tcp->pid, ntid); 1003 } 1004 if (!(tcp->flags & TCB_ATTACHED)) { 1005 /* -p PID, we failed to attach to PID itself 1006 * but did attach to some of its sibling threads. 1007 * Drop PID's tcp. 1008 */ 1009 droptcb(tcp); 1010 } 1011 continue; 1012 } /* if (opendir worked) */ 1013 } /* if (-f) */ 1014 if (ptrace_attach_or_seize(tcp->pid) < 0) { 1015 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1016 droptcb(tcp); 1017 continue; 1018 } 1019 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1020 newoutf(tcp); 1021 if (debug_flag) 1022 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid); 1023 1024 if (daemonized_tracer) { 1025 /* 1026 * Make parent go away. 1027 * Also makes grandparent's wait() unblock. 1028 */ 1029 kill(getppid(), SIGKILL); 1030 } 1031 1032 if (!qflag) 1033 fprintf(stderr, 1034 "Process %u attached\n", 1035 tcp->pid); 1036 } /* for each tcbtab[] */ 1037 1038 ret: 1039 if (interactive) 1040 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1041} 1042 1043/* Stack-o-phobic exec helper, in the hope to work around 1044 * NOMMU + "daemonized tracer" difficulty. 1045 */ 1046struct exec_params { 1047 int fd_to_close; 1048 uid_t run_euid; 1049 gid_t run_egid; 1050 char **argv; 1051 char *pathname; 1052}; 1053static struct exec_params params_for_tracee; 1054static void __attribute__ ((noinline, noreturn)) 1055exec_or_die(void) 1056{ 1057 struct exec_params *params = ¶ms_for_tracee; 1058 1059 if (params->fd_to_close >= 0) 1060 close(params->fd_to_close); 1061 if (!daemonized_tracer && !use_seize) { 1062 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) { 1063 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)"); 1064 } 1065 } 1066 1067 if (username != NULL) { 1068 /* 1069 * It is important to set groups before we 1070 * lose privileges on setuid. 1071 */ 1072 if (initgroups(username, run_gid) < 0) { 1073 perror_msg_and_die("initgroups"); 1074 } 1075 if (setregid(run_gid, params->run_egid) < 0) { 1076 perror_msg_and_die("setregid"); 1077 } 1078 if (setreuid(run_uid, params->run_euid) < 0) { 1079 perror_msg_and_die("setreuid"); 1080 } 1081 } 1082 else if (geteuid() != 0) 1083 if (setreuid(run_uid, run_uid) < 0) { 1084 perror_msg_and_die("setreuid"); 1085 } 1086 1087 if (!daemonized_tracer) { 1088 /* 1089 * Induce a ptrace stop. Tracer (our parent) 1090 * will resume us with PTRACE_SYSCALL and display 1091 * the immediately following execve syscall. 1092 * Can't do this on NOMMU systems, we are after 1093 * vfork: parent is blocked, stopping would deadlock. 1094 */ 1095 if (!NOMMU_SYSTEM) 1096 kill(getpid(), SIGSTOP); 1097 } else { 1098 alarm(3); 1099 /* we depend on SIGCHLD set to SIG_DFL by init code */ 1100 /* if it happens to be SIG_IGN'ed, wait won't block */ 1101 wait(NULL); 1102 alarm(0); 1103 } 1104 1105 execv(params->pathname, params->argv); 1106 perror_msg_and_die("exec"); 1107} 1108 1109static void 1110startup_child(char **argv) 1111{ 1112 struct_stat statbuf; 1113 const char *filename; 1114 char pathname[MAXPATHLEN]; 1115 int pid; 1116 struct tcb *tcp; 1117 1118 filename = argv[0]; 1119 if (strchr(filename, '/')) { 1120 if (strlen(filename) > sizeof pathname - 1) { 1121 errno = ENAMETOOLONG; 1122 perror_msg_and_die("exec"); 1123 } 1124 strcpy(pathname, filename); 1125 } 1126#ifdef USE_DEBUGGING_EXEC 1127 /* 1128 * Debuggers customarily check the current directory 1129 * first regardless of the path but doing that gives 1130 * security geeks a panic attack. 1131 */ 1132 else if (stat_file(filename, &statbuf) == 0) 1133 strcpy(pathname, filename); 1134#endif /* USE_DEBUGGING_EXEC */ 1135 else { 1136 const char *path; 1137 int m, n, len; 1138 1139 for (path = getenv("PATH"); path && *path; path += m) { 1140 const char *colon = strchr(path, ':'); 1141 if (colon) { 1142 n = colon - path; 1143 m = n + 1; 1144 } 1145 else 1146 m = n = strlen(path); 1147 if (n == 0) { 1148 if (!getcwd(pathname, MAXPATHLEN)) 1149 continue; 1150 len = strlen(pathname); 1151 } 1152 else if (n > sizeof pathname - 1) 1153 continue; 1154 else { 1155 strncpy(pathname, path, n); 1156 len = n; 1157 } 1158 if (len && pathname[len - 1] != '/') 1159 pathname[len++] = '/'; 1160 strcpy(pathname + len, filename); 1161 if (stat_file(pathname, &statbuf) == 0 && 1162 /* Accept only regular files 1163 with some execute bits set. 1164 XXX not perfect, might still fail */ 1165 S_ISREG(statbuf.st_mode) && 1166 (statbuf.st_mode & 0111)) 1167 break; 1168 } 1169 } 1170 if (stat_file(pathname, &statbuf) < 0) { 1171 perror_msg_and_die("Can't stat '%s'", filename); 1172 } 1173 1174 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1; 1175 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid; 1176 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid; 1177 params_for_tracee.argv = argv; 1178 /* 1179 * On NOMMU, can be safely freed only after execve in tracee. 1180 * It's hard to know when that happens, so we just leak it. 1181 */ 1182 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname; 1183 1184#if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY 1185 if (daemonized_tracer) 1186 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY); 1187#endif 1188 1189 strace_child = pid = fork(); 1190 if (pid < 0) { 1191 perror_msg_and_die("fork"); 1192 } 1193 if ((pid != 0 && daemonized_tracer) 1194 || (pid == 0 && !daemonized_tracer) 1195 ) { 1196 /* We are to become the tracee. Two cases: 1197 * -D: we are parent 1198 * not -D: we are child 1199 */ 1200 exec_or_die(); 1201 } 1202 1203 /* We are the tracer */ 1204 1205 if (!daemonized_tracer) { 1206 if (!use_seize) { 1207 /* child did PTRACE_TRACEME, nothing to do in parent */ 1208 } else { 1209 if (!NOMMU_SYSTEM) { 1210 /* Wait until child stopped itself */ 1211 int status; 1212 while (waitpid(pid, &status, WSTOPPED) < 0) { 1213 if (errno == EINTR) 1214 continue; 1215 perror_msg_and_die("waitpid"); 1216 } 1217 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) { 1218 kill_save_errno(pid, SIGKILL); 1219 perror_msg_and_die("Unexpected wait status %x", status); 1220 } 1221 } 1222 /* Else: NOMMU case, we have no way to sync. 1223 * Just attach to it as soon as possible. 1224 * This means that we may miss a few first syscalls... 1225 */ 1226 1227 if (ptrace_attach_or_seize(pid)) { 1228 kill_save_errno(pid, SIGKILL); 1229 perror_msg_and_die("Can't attach to %d", pid); 1230 } 1231 if (!NOMMU_SYSTEM) 1232 kill(pid, SIGCONT); 1233 } 1234 tcp = alloctcb(pid); 1235 if (!NOMMU_SYSTEM) 1236 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP | post_attach_sigstop; 1237 else 1238 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP; 1239 newoutf(tcp); 1240 } 1241 else { 1242 /* With -D, we are *child* here, IOW: different pid. Fetch it: */ 1243 strace_tracer_pid = getpid(); 1244 /* The tracee is our parent: */ 1245 pid = getppid(); 1246 alloctcb(pid); 1247 /* attaching will be done later, by startup_attach */ 1248 /* note: we don't do newoutf(tcp) here either! */ 1249 1250 /* NOMMU BUG! -D mode is active, we (child) return, 1251 * and we will scribble over parent's stack! 1252 * When parent later unpauses, it segfaults. 1253 * 1254 * We work around it 1255 * (1) by declaring exec_or_die() NORETURN, 1256 * hopefully compiler will just jump to it 1257 * instead of call (won't push anything to stack), 1258 * (2) by trying very hard in exec_or_die() 1259 * to not use any stack, 1260 * (3) having a really big (MAXPATHLEN) stack object 1261 * in this function, which creates a "buffer" between 1262 * child's and parent's stack pointers. 1263 * This may save us if (1) and (2) failed 1264 * and compiler decided to use stack in exec_or_die() anyway 1265 * (happens on i386 because of stack parameter passing). 1266 * 1267 * A cleaner solution is to use makecontext + setcontext 1268 * to create a genuine separate stack and execute on it. 1269 */ 1270 } 1271} 1272 1273/* 1274 * Test whether the kernel support PTRACE_O_TRACECLONE et al options. 1275 * First fork a new child, call ptrace with PTRACE_SETOPTIONS on it, 1276 * and then see which options are supported by the kernel. 1277 */ 1278static int 1279test_ptrace_setoptions_followfork(void) 1280{ 1281 int pid, expected_grandchild = 0, found_grandchild = 0; 1282 const unsigned int test_options = PTRACE_O_TRACECLONE | 1283 PTRACE_O_TRACEFORK | 1284 PTRACE_O_TRACEVFORK; 1285 1286 /* Need fork for test. NOMMU has no forks */ 1287 if (NOMMU_SYSTEM) 1288 goto worked; /* be bold, and pretend that test succeeded */ 1289 1290 pid = fork(); 1291 if (pid < 0) 1292 perror_msg_and_die("fork"); 1293 if (pid == 0) { 1294 pid = getpid(); 1295 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1296 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1297 __func__); 1298 kill_save_errno(pid, SIGSTOP); 1299 if (fork() < 0) 1300 perror_msg_and_die("fork"); 1301 _exit(0); 1302 } 1303 1304 while (1) { 1305 int status, tracee_pid; 1306 1307 errno = 0; 1308 tracee_pid = wait(&status); 1309 if (tracee_pid <= 0) { 1310 if (errno == EINTR) 1311 continue; 1312 if (errno == ECHILD) 1313 break; 1314 kill_save_errno(pid, SIGKILL); 1315 perror_msg_and_die("%s: unexpected wait result %d", 1316 __func__, tracee_pid); 1317 } 1318 if (WIFEXITED(status)) { 1319 if (WEXITSTATUS(status)) { 1320 if (tracee_pid != pid) 1321 kill_save_errno(pid, SIGKILL); 1322 error_msg_and_die("%s: unexpected exit status %u", 1323 __func__, WEXITSTATUS(status)); 1324 } 1325 continue; 1326 } 1327 if (WIFSIGNALED(status)) { 1328 if (tracee_pid != pid) 1329 kill_save_errno(pid, SIGKILL); 1330 error_msg_and_die("%s: unexpected signal %u", 1331 __func__, WTERMSIG(status)); 1332 } 1333 if (!WIFSTOPPED(status)) { 1334 if (tracee_pid != pid) 1335 kill_save_errno(tracee_pid, SIGKILL); 1336 kill_save_errno(pid, SIGKILL); 1337 error_msg_and_die("%s: unexpected wait status %x", 1338 __func__, status); 1339 } 1340 if (tracee_pid != pid) { 1341 found_grandchild = tracee_pid; 1342 if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0) { 1343 kill_save_errno(tracee_pid, SIGKILL); 1344 kill_save_errno(pid, SIGKILL); 1345 perror_msg_and_die("PTRACE_CONT doesn't work"); 1346 } 1347 continue; 1348 } 1349 switch (WSTOPSIG(status)) { 1350 case SIGSTOP: 1351 if (ptrace(PTRACE_SETOPTIONS, pid, 0, test_options) < 0 1352 && errno != EINVAL && errno != EIO) 1353 perror_msg("PTRACE_SETOPTIONS"); 1354 break; 1355 case SIGTRAP: 1356 if (status >> 16 == PTRACE_EVENT_FORK) { 1357 long msg = 0; 1358 1359 if (ptrace(PTRACE_GETEVENTMSG, pid, 1360 NULL, (long) &msg) == 0) 1361 expected_grandchild = msg; 1362 } 1363 break; 1364 } 1365 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) { 1366 kill_save_errno(pid, SIGKILL); 1367 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1368 } 1369 } 1370 if (expected_grandchild && expected_grandchild == found_grandchild) { 1371 worked: 1372 ptrace_setoptions |= test_options; 1373 if (debug_flag) 1374 fprintf(stderr, "ptrace_setoptions = %#x\n", 1375 ptrace_setoptions); 1376 return 0; 1377 } 1378 error_msg("Test for PTRACE_O_TRACECLONE failed, " 1379 "giving up using this feature."); 1380 return 1; 1381} 1382 1383/* 1384 * Test whether the kernel support PTRACE_O_TRACESYSGOOD. 1385 * First fork a new child, call ptrace(PTRACE_SETOPTIONS) on it, 1386 * and then see whether it will stop with (SIGTRAP | 0x80). 1387 * 1388 * Use of this option enables correct handling of user-generated SIGTRAPs, 1389 * and SIGTRAPs generated by special instructions such as int3 on x86: 1390 * _start: .globl _start 1391 * int3 1392 * movl $42, %ebx 1393 * movl $1, %eax 1394 * int $0x80 1395 * (compile with: "gcc -nostartfiles -nostdlib -o int3 int3.S") 1396 */ 1397static int 1398test_ptrace_setoptions_for_all(void) 1399{ 1400 const unsigned int test_options = PTRACE_O_TRACESYSGOOD | 1401 PTRACE_O_TRACEEXEC; 1402 int pid; 1403 int it_worked = 0; 1404 1405 /* Need fork for test. NOMMU has no forks */ 1406 if (NOMMU_SYSTEM) 1407 goto worked; /* be bold, and pretend that test succeeded */ 1408 1409 pid = fork(); 1410 if (pid < 0) 1411 perror_msg_and_die("fork"); 1412 1413 if (pid == 0) { 1414 pid = getpid(); 1415 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1416 /* Note: exits with exitcode 1 */ 1417 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1418 __func__); 1419 kill(pid, SIGSTOP); 1420 _exit(0); /* parent should see entry into this syscall */ 1421 } 1422 1423 while (1) { 1424 int status, tracee_pid; 1425 1426 errno = 0; 1427 tracee_pid = wait(&status); 1428 if (tracee_pid <= 0) { 1429 if (errno == EINTR) 1430 continue; 1431 kill_save_errno(pid, SIGKILL); 1432 perror_msg_and_die("%s: unexpected wait result %d", 1433 __func__, tracee_pid); 1434 } 1435 if (WIFEXITED(status)) { 1436 if (WEXITSTATUS(status) == 0) 1437 break; 1438 error_msg_and_die("%s: unexpected exit status %u", 1439 __func__, WEXITSTATUS(status)); 1440 } 1441 if (WIFSIGNALED(status)) { 1442 error_msg_and_die("%s: unexpected signal %u", 1443 __func__, WTERMSIG(status)); 1444 } 1445 if (!WIFSTOPPED(status)) { 1446 kill(pid, SIGKILL); 1447 error_msg_and_die("%s: unexpected wait status %x", 1448 __func__, status); 1449 } 1450 if (WSTOPSIG(status) == SIGSTOP) { 1451 /* 1452 * We don't check "options aren't accepted" error. 1453 * If it happens, we'll never get (SIGTRAP | 0x80), 1454 * and thus will decide to not use the option. 1455 * IOW: the outcome of the test will be correct. 1456 */ 1457 if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0 1458 && errno != EINVAL && errno != EIO) 1459 perror_msg("PTRACE_SETOPTIONS"); 1460 } 1461 if (WSTOPSIG(status) == (SIGTRAP | 0x80)) { 1462 it_worked = 1; 1463 } 1464 if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) { 1465 kill_save_errno(pid, SIGKILL); 1466 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1467 } 1468 } 1469 1470 if (it_worked) { 1471 worked: 1472 syscall_trap_sig = (SIGTRAP | 0x80); 1473 ptrace_setoptions |= test_options; 1474 if (debug_flag) 1475 fprintf(stderr, "ptrace_setoptions = %#x\n", 1476 ptrace_setoptions); 1477 return 0; 1478 } 1479 1480 error_msg("Test for PTRACE_O_TRACESYSGOOD failed, " 1481 "giving up using this feature."); 1482 return 1; 1483} 1484 1485#if USE_SEIZE 1486static void 1487test_ptrace_seize(void) 1488{ 1489 int pid; 1490 1491 /* Need fork for test. NOMMU has no forks */ 1492 if (NOMMU_SYSTEM) { 1493 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1494 return; 1495 } 1496 1497 pid = fork(); 1498 if (pid < 0) 1499 perror_msg_and_die("fork"); 1500 1501 if (pid == 0) { 1502 pause(); 1503 _exit(0); 1504 } 1505 1506 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After 1507 * attaching tracee continues to run unless a trap condition occurs. 1508 * PTRACE_SEIZE doesn't affect signal or group stop state. 1509 */ 1510 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) { 1511 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1512 } else if (debug_flag) { 1513 fprintf(stderr, "PTRACE_SEIZE doesn't work\n"); 1514 } 1515 1516 kill(pid, SIGKILL); 1517 1518 while (1) { 1519 int status, tracee_pid; 1520 1521 errno = 0; 1522 tracee_pid = waitpid(pid, &status, 0); 1523 if (tracee_pid <= 0) { 1524 if (errno == EINTR) 1525 continue; 1526 perror_msg_and_die("%s: unexpected wait result %d", 1527 __func__, tracee_pid); 1528 } 1529 if (WIFSIGNALED(status)) { 1530 return; 1531 } 1532 error_msg_and_die("%s: unexpected wait status %x", 1533 __func__, status); 1534 } 1535} 1536#else /* !USE_SEIZE */ 1537# define test_ptrace_seize() ((void)0) 1538#endif 1539 1540static unsigned 1541get_os_release(void) 1542{ 1543 unsigned rel; 1544 const char *p; 1545 struct utsname u; 1546 if (uname(&u) < 0) 1547 perror_msg_and_die("uname"); 1548 /* u.release has this form: "3.2.9[-some-garbage]" */ 1549 rel = 0; 1550 p = u.release; 1551 for (;;) { 1552 if (!(*p >= '0' && *p <= '9')) 1553 error_msg_and_die("Bad OS release string: '%s'", u.release); 1554 /* Note: this open-codes KERNEL_VERSION(): */ 1555 rel = (rel << 8) | atoi(p); 1556 if (rel >= KERNEL_VERSION(1,0,0)) 1557 break; 1558 while (*p >= '0' && *p <= '9') 1559 p++; 1560 if (*p != '.') { 1561 if (rel >= KERNEL_VERSION(0,1,0)) { 1562 /* "X.Y-something" means "X.Y.0" */ 1563 rel <<= 8; 1564 break; 1565 } 1566 error_msg_and_die("Bad OS release string: '%s'", u.release); 1567 } 1568 p++; 1569 } 1570 return rel; 1571} 1572 1573/* 1574 * Initialization part of main() was eating much stack (~0.5k), 1575 * which was unused after init. 1576 * We can reuse it if we move init code into a separate function. 1577 * 1578 * Don't want main() to inline us and defeat the reason 1579 * we have a separate function. 1580 */ 1581static void __attribute__ ((noinline)) 1582init(int argc, char *argv[]) 1583{ 1584 struct tcb *tcp; 1585 int c, i; 1586 int optF = 0; 1587 struct sigaction sa; 1588 1589 progname = argv[0] ? argv[0] : "strace"; 1590 1591 /* Make sure SIGCHLD has the default action so that waitpid 1592 definitely works without losing track of children. The user 1593 should not have given us a bogus state to inherit, but he might 1594 have. Arguably we should detect SIG_IGN here and pass it on 1595 to children, but probably noone really needs that. */ 1596 signal(SIGCHLD, SIG_DFL); 1597 1598 strace_tracer_pid = getpid(); 1599 1600 os_release = get_os_release(); 1601 1602 /* Allocate the initial tcbtab. */ 1603 tcbtabsize = argc; /* Surely enough for all -p args. */ 1604 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0])); 1605 if (!tcbtab) 1606 die_out_of_memory(); 1607 tcp = calloc(tcbtabsize, sizeof(*tcp)); 1608 if (!tcp) 1609 die_out_of_memory(); 1610 for (c = 0; c < tcbtabsize; c++) 1611 tcbtab[c] = tcp++; 1612 1613 shared_log = stderr; 1614 set_sortby(DEFAULT_SORTBY); 1615 set_personality(DEFAULT_PERSONALITY); 1616 qualify("trace=all"); 1617 qualify("abbrev=all"); 1618 qualify("verbose=all"); 1619#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE) 1620# error Bug in DEFAULT_QUAL_FLAGS 1621#endif 1622 qualify("signal=all"); 1623 while ((c = getopt(argc, argv, 1624 "+b:cCdfFhiqrtTvVxyz" 1625 "D" 1626 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) { 1627 switch (c) { 1628 case 'b': 1629 if (strcmp(optarg, "execve") != 0) 1630 error_msg_and_die("Syscall '%s' for -b isn't supported", 1631 optarg); 1632 detach_on_execve = 1; 1633 break; 1634 case 'c': 1635 if (cflag == CFLAG_BOTH) { 1636 error_msg_and_die("-c and -C are mutually exclusive"); 1637 } 1638 cflag = CFLAG_ONLY_STATS; 1639 break; 1640 case 'C': 1641 if (cflag == CFLAG_ONLY_STATS) { 1642 error_msg_and_die("-c and -C are mutually exclusive"); 1643 } 1644 cflag = CFLAG_BOTH; 1645 break; 1646 case 'd': 1647 debug_flag = 1; 1648 break; 1649 case 'D': 1650 daemonized_tracer = 1; 1651 break; 1652 case 'F': 1653 optF = 1; 1654 break; 1655 case 'f': 1656 followfork++; 1657 break; 1658 case 'h': 1659 usage(stdout, 0); 1660 break; 1661 case 'i': 1662 iflag = 1; 1663 break; 1664 case 'q': 1665 qflag++; 1666 break; 1667 case 'r': 1668 rflag = 1; 1669 /* fall through to tflag++ */ 1670 case 't': 1671 tflag++; 1672 break; 1673 case 'T': 1674 Tflag = 1; 1675 break; 1676 case 'x': 1677 xflag++; 1678 break; 1679 case 'y': 1680 show_fd_path = 1; 1681 break; 1682 case 'v': 1683 qualify("abbrev=none"); 1684 break; 1685 case 'V': 1686 printf("%s -- version %s\n", PACKAGE_NAME, VERSION); 1687 exit(0); 1688 break; 1689 case 'z': 1690 not_failing_only = 1; 1691 break; 1692 case 'a': 1693 acolumn = string_to_uint(optarg); 1694 if (acolumn < 0) 1695 error_opt_arg(c, optarg); 1696 break; 1697 case 'e': 1698 qualify(optarg); 1699 break; 1700 case 'o': 1701 outfname = strdup(optarg); 1702 break; 1703 case 'O': 1704 i = string_to_uint(optarg); 1705 if (i < 0) 1706 error_opt_arg(c, optarg); 1707 set_overhead(i); 1708 break; 1709 case 'p': 1710 process_opt_p_list(optarg); 1711 break; 1712 case 'P': 1713 pathtrace_select(optarg); 1714 break; 1715 case 's': 1716 i = string_to_uint(optarg); 1717 if (i < 0) 1718 error_opt_arg(c, optarg); 1719 max_strlen = i; 1720 break; 1721 case 'S': 1722 set_sortby(optarg); 1723 break; 1724 case 'u': 1725 username = strdup(optarg); 1726 break; 1727 case 'E': 1728 if (putenv(optarg) < 0) 1729 die_out_of_memory(); 1730 break; 1731 case 'I': 1732 opt_intr = string_to_uint(optarg); 1733 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS) 1734 error_opt_arg(c, optarg); 1735 break; 1736 default: 1737 usage(stderr, 1); 1738 break; 1739 } 1740 } 1741 argv += optind; 1742 /* argc -= optind; - no need, argc is not used below */ 1743 1744 acolumn_spaces = malloc(acolumn + 1); 1745 if (!acolumn_spaces) 1746 die_out_of_memory(); 1747 memset(acolumn_spaces, ' ', acolumn); 1748 acolumn_spaces[acolumn] = '\0'; 1749 1750 /* Must have PROG [ARGS], or -p PID. Not both. */ 1751 if (!argv[0] == !nprocs) 1752 usage(stderr, 1); 1753 1754 if (nprocs != 0 && daemonized_tracer) { 1755 error_msg_and_die("-D and -p are mutually exclusive"); 1756 } 1757 1758 if (!followfork) 1759 followfork = optF; 1760 1761 if (followfork >= 2 && cflag) { 1762 error_msg_and_die("(-c or -C) and -ff are mutually exclusive"); 1763 } 1764 1765 /* See if they want to run as another user. */ 1766 if (username != NULL) { 1767 struct passwd *pent; 1768 1769 if (getuid() != 0 || geteuid() != 0) { 1770 error_msg_and_die("You must be root to use the -u option"); 1771 } 1772 pent = getpwnam(username); 1773 if (pent == NULL) { 1774 error_msg_and_die("Cannot find user '%s'", username); 1775 } 1776 run_uid = pent->pw_uid; 1777 run_gid = pent->pw_gid; 1778 } 1779 else { 1780 run_uid = getuid(); 1781 run_gid = getgid(); 1782 } 1783 1784 /* 1785 * On any reasonably recent Linux kernel (circa about 2.5.46) 1786 * need_fork_exec_workarounds should stay 0 after these tests: 1787 */ 1788 /*need_fork_exec_workarounds = 0; - already is */ 1789 if (followfork) 1790 need_fork_exec_workarounds = test_ptrace_setoptions_followfork(); 1791 need_fork_exec_workarounds |= test_ptrace_setoptions_for_all(); 1792 test_ptrace_seize(); 1793 1794 /* Check if they want to redirect the output. */ 1795 if (outfname) { 1796 /* See if they want to pipe the output. */ 1797 if (outfname[0] == '|' || outfname[0] == '!') { 1798 /* 1799 * We can't do the <outfname>.PID funny business 1800 * when using popen, so prohibit it. 1801 */ 1802 if (followfork >= 2) 1803 error_msg_and_die("Piping the output and -ff are mutually exclusive"); 1804 shared_log = strace_popen(outfname + 1); 1805 } 1806 else if (followfork < 2) 1807 shared_log = strace_fopen(outfname); 1808 } else { 1809 /* -ff without -o FILE is the same as single -f */ 1810 if (followfork >= 2) 1811 followfork = 1; 1812 } 1813 1814 if (!outfname || outfname[0] == '|' || outfname[0] == '!') { 1815 char *buf = malloc(BUFSIZ); 1816 if (!buf) 1817 die_out_of_memory(); 1818 setvbuf(shared_log, buf, _IOLBF, BUFSIZ); 1819 } 1820 if (outfname && argv[0]) { 1821 if (!opt_intr) 1822 opt_intr = INTR_NEVER; 1823 qflag = 1; 1824 } 1825 if (!opt_intr) 1826 opt_intr = INTR_WHILE_WAIT; 1827 1828 /* argv[0] -pPID -oFILE Default interactive setting 1829 * yes 0 0 INTR_WHILE_WAIT 1830 * no 1 0 INTR_WHILE_WAIT 1831 * yes 0 1 INTR_NEVER 1832 * no 1 1 INTR_WHILE_WAIT 1833 */ 1834 1835 sigemptyset(&empty_set); 1836 sigemptyset(&blocked_set); 1837 1838 /* startup_child() must be called before the signal handlers get 1839 * installed below as they are inherited into the spawned process. 1840 * Also we do not need to be protected by them as during interruption 1841 * in the startup_child() mode we kill the spawned process anyway. 1842 */ 1843 if (argv[0]) { 1844 if (!NOMMU_SYSTEM || daemonized_tracer) 1845 hide_log_until_execve = 1; 1846 skip_one_b_execve = 1; 1847 startup_child(argv); 1848 } 1849 1850 sa.sa_handler = SIG_IGN; 1851 sigemptyset(&sa.sa_mask); 1852 sa.sa_flags = 0; 1853 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */ 1854 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */ 1855 if (opt_intr != INTR_ANYWHERE) { 1856 if (opt_intr == INTR_BLOCK_TSTP_TOO) 1857 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */ 1858 /* 1859 * In interactive mode (if no -o OUTFILE, or -p PID is used), 1860 * fatal signals are blocked while syscall stop is processed, 1861 * and acted on in between, when waiting for new syscall stops. 1862 * In non-interactive mode, signals are ignored. 1863 */ 1864 if (opt_intr == INTR_WHILE_WAIT) { 1865 sigaddset(&blocked_set, SIGHUP); 1866 sigaddset(&blocked_set, SIGINT); 1867 sigaddset(&blocked_set, SIGQUIT); 1868 sigaddset(&blocked_set, SIGPIPE); 1869 sigaddset(&blocked_set, SIGTERM); 1870 sa.sa_handler = interrupt; 1871 } 1872 /* SIG_IGN, or set handler for these */ 1873 sigaction(SIGHUP, &sa, NULL); 1874 sigaction(SIGINT, &sa, NULL); 1875 sigaction(SIGQUIT, &sa, NULL); 1876 sigaction(SIGPIPE, &sa, NULL); 1877 sigaction(SIGTERM, &sa, NULL); 1878 } 1879 if (nprocs != 0 || daemonized_tracer) 1880 startup_attach(); 1881 1882 /* Do we want pids printed in our -o OUTFILE? 1883 * -ff: no (every pid has its own file); or 1884 * -f: yes (there can be more pids in the future); or 1885 * -p PID1,PID2: yes (there are already more than one pid) 1886 */ 1887 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1)); 1888} 1889 1890static struct tcb * 1891pid2tcb(int pid) 1892{ 1893 int i; 1894 1895 if (pid <= 0) 1896 return NULL; 1897 1898 for (i = 0; i < tcbtabsize; i++) { 1899 struct tcb *tcp = tcbtab[i]; 1900 if (tcp->pid == pid && (tcp->flags & TCB_INUSE)) 1901 return tcp; 1902 } 1903 1904 return NULL; 1905} 1906 1907static void 1908cleanup(void) 1909{ 1910 int i; 1911 struct tcb *tcp; 1912 int fatal_sig; 1913 1914 /* 'interrupted' is a volatile object, fetch it only once */ 1915 fatal_sig = interrupted; 1916 if (!fatal_sig) 1917 fatal_sig = SIGTERM; 1918 1919 for (i = 0; i < tcbtabsize; i++) { 1920 tcp = tcbtab[i]; 1921 if (!(tcp->flags & TCB_INUSE)) 1922 continue; 1923 if (debug_flag) 1924 fprintf(stderr, 1925 "cleanup: looking at pid %u\n", tcp->pid); 1926 if (tcp->flags & TCB_STRACE_CHILD) { 1927 kill(tcp->pid, SIGCONT); 1928 kill(tcp->pid, fatal_sig); 1929 } 1930 detach(tcp); 1931 } 1932 if (cflag) 1933 call_summary(shared_log); 1934} 1935 1936static void 1937interrupt(int sig) 1938{ 1939 interrupted = sig; 1940} 1941 1942static int 1943trace(void) 1944{ 1945 struct rusage ru; 1946 1947 while (nprocs != 0) { 1948 int pid; 1949 int wait_errno; 1950 int status, sig; 1951 int stopped; 1952 struct tcb *tcp; 1953 unsigned event; 1954 1955 if (interrupted) 1956 return 0; 1957 1958 if (interactive) 1959 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1960 pid = wait4(-1, &status, __WALL, (cflag ? &ru : NULL)); 1961 wait_errno = errno; 1962 if (interactive) 1963 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1964 1965 if (pid < 0) { 1966 if (wait_errno == EINTR) 1967 continue; 1968 if (wait_errno == ECHILD) 1969 /* Should not happen since nprocs > 0 */ 1970 return 0; 1971 errno = wait_errno; 1972 perror_msg("wait4(__WALL)"); 1973 return -1; 1974 } 1975 1976 if (pid == popen_pid) { 1977 if (WIFEXITED(status) || WIFSIGNALED(status)) 1978 popen_pid = 0; 1979 continue; 1980 } 1981 1982 event = ((unsigned)status >> 16); 1983 if (debug_flag) { 1984 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16]; 1985 char evbuf[sizeof(",PTRACE_EVENT_?? (%u)") + sizeof(int)*3 /*paranoia:*/ + 16]; 1986 strcpy(buf, "???"); 1987 if (WIFSIGNALED(status)) 1988#ifdef WCOREDUMP 1989 sprintf(buf, "WIFSIGNALED,%ssig=%s", 1990 WCOREDUMP(status) ? "core," : "", 1991 signame(WTERMSIG(status))); 1992#else 1993 sprintf(buf, "WIFSIGNALED,sig=%s", 1994 signame(WTERMSIG(status))); 1995#endif 1996 if (WIFEXITED(status)) 1997 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status)); 1998 if (WIFSTOPPED(status)) 1999 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status))); 2000#ifdef WIFCONTINUED 2001 if (WIFCONTINUED(status)) 2002 strcpy(buf, "WIFCONTINUED"); 2003#endif 2004 evbuf[0] = '\0'; 2005 if (event != 0) { 2006 static const char *const event_names[] = { 2007 [PTRACE_EVENT_CLONE] = "CLONE", 2008 [PTRACE_EVENT_FORK] = "FORK", 2009 [PTRACE_EVENT_VFORK] = "VFORK", 2010 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE", 2011 [PTRACE_EVENT_EXEC] = "EXEC", 2012 [PTRACE_EVENT_EXIT] = "EXIT", 2013 }; 2014 const char *e; 2015 if (event < ARRAY_SIZE(event_names)) 2016 e = event_names[event]; 2017 else { 2018 sprintf(buf, "?? (%u)", event); 2019 e = buf; 2020 } 2021 sprintf(evbuf, ",PTRACE_EVENT_%s", e); 2022 } 2023 fprintf(stderr, " [wait(0x%04x) = %u] %s%s\n", status, pid, buf, evbuf); 2024 } 2025 2026 /* Look up 'pid' in our table. */ 2027 tcp = pid2tcb(pid); 2028 2029 if (!tcp) { 2030 if (followfork) { 2031 tcp = alloctcb(pid); 2032 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 2033 newoutf(tcp); 2034 if (!qflag) 2035 fprintf(stderr, "Process %d attached\n", 2036 pid); 2037 } else { 2038 /* This can happen if a clone call used 2039 CLONE_PTRACE itself. */ 2040 if (WIFSTOPPED(status)) 2041 ptrace(PTRACE_CONT, pid, (char *) 0, 0); 2042 error_msg_and_die("Unknown pid: %u", pid); 2043 } 2044 } 2045 2046 clear_regs(); 2047 if (WIFSTOPPED(status)) 2048 get_regs(pid); 2049 2050 /* Under Linux, execve changes pid to thread leader's pid, 2051 * and we see this changed pid on EVENT_EXEC and later, 2052 * execve sysexit. Leader "disappears" without exit 2053 * notification. Let user know that, drop leader's tcb, 2054 * and fix up pid in execve thread's tcb. 2055 * Effectively, execve thread's tcb replaces leader's tcb. 2056 * 2057 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED 2058 * on exit syscall) in multithreaded programs exactly 2059 * in order to handle this case. 2060 * 2061 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0. 2062 * On 2.6 and earlier, it can return garbage. 2063 */ 2064 if (event == PTRACE_EVENT_EXEC && os_release >= KERNEL_VERSION(3,0,0)) { 2065 FILE *fp; 2066 struct tcb *execve_thread; 2067 long old_pid = 0; 2068 2069 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0) 2070 goto dont_switch_tcbs; 2071 if (old_pid <= 0 || old_pid == pid) 2072 goto dont_switch_tcbs; 2073 execve_thread = pid2tcb(old_pid); 2074 /* It should be !NULL, but I feel paranoid */ 2075 if (!execve_thread) 2076 goto dont_switch_tcbs; 2077 2078 if (execve_thread->curcol != 0) { 2079 /* 2080 * One case we are here is -ff: 2081 * try "strace -oLOG -ff test/threaded_execve" 2082 */ 2083 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid); 2084 /*execve_thread->curcol = 0; - no need, see code below */ 2085 } 2086 /* Swap output FILEs (needed for -ff) */ 2087 fp = execve_thread->outf; 2088 execve_thread->outf = tcp->outf; 2089 tcp->outf = fp; 2090 /* And their column positions */ 2091 execve_thread->curcol = tcp->curcol; 2092 tcp->curcol = 0; 2093 /* Drop leader, but close execve'd thread outfile (if -ff) */ 2094 droptcb(tcp); 2095 /* Switch to the thread, reusing leader's outfile and pid */ 2096 tcp = execve_thread; 2097 tcp->pid = pid; 2098 if (cflag != CFLAG_ONLY_STATS) { 2099 printleader(tcp); 2100 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid); 2101 line_ended(); 2102 tcp->flags |= TCB_REPRINT; 2103 } 2104 } 2105 dont_switch_tcbs: 2106 2107 if (event == PTRACE_EVENT_EXEC) { 2108 if (detach_on_execve && !skip_one_b_execve) 2109 detach(tcp); /* do "-b execve" thingy */ 2110 skip_one_b_execve = 0; 2111 } 2112 2113 /* Set current output file */ 2114 current_tcp = tcp; 2115 2116 if (cflag) { 2117 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime); 2118 tcp->stime = ru.ru_stime; 2119 } 2120 2121 if (WIFSIGNALED(status)) { 2122 if (pid == strace_child) 2123 exit_code = 0x100 | WTERMSIG(status); 2124 if (cflag != CFLAG_ONLY_STATS 2125 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL) 2126 ) { 2127 printleader(tcp); 2128#ifdef WCOREDUMP 2129 tprintf("+++ killed by %s %s+++\n", 2130 signame(WTERMSIG(status)), 2131 WCOREDUMP(status) ? "(core dumped) " : ""); 2132#else 2133 tprintf("+++ killed by %s +++\n", 2134 signame(WTERMSIG(status))); 2135#endif 2136 line_ended(); 2137 } 2138 droptcb(tcp); 2139 continue; 2140 } 2141 if (WIFEXITED(status)) { 2142 if (pid == strace_child) 2143 exit_code = WEXITSTATUS(status); 2144 if (cflag != CFLAG_ONLY_STATS && 2145 qflag < 2) { 2146 printleader(tcp); 2147 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status)); 2148 line_ended(); 2149 } 2150 droptcb(tcp); 2151 continue; 2152 } 2153 if (!WIFSTOPPED(status)) { 2154 fprintf(stderr, "PANIC: pid %u not stopped\n", pid); 2155 droptcb(tcp); 2156 continue; 2157 } 2158 2159 /* Is this the very first time we see this tracee stopped? */ 2160 if (tcp->flags & TCB_STARTUP) { 2161 if (debug_flag) 2162 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n", tcp->pid); 2163 tcp->flags &= ~TCB_STARTUP; 2164 if (tcp->flags & TCB_BPTSET) { 2165 /* 2166 * One example is a breakpoint inherited from 2167 * parent through fork(). 2168 */ 2169 if (clearbpt(tcp) < 0) { 2170 /* Pretty fatal */ 2171 droptcb(tcp); 2172 cleanup(); 2173 return -1; 2174 } 2175 } 2176 if (ptrace_setoptions) { 2177 if (debug_flag) 2178 fprintf(stderr, "setting opts %x on pid %d\n", ptrace_setoptions, tcp->pid); 2179 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) { 2180 if (errno != ESRCH) { 2181 /* Should never happen, really */ 2182 perror_msg_and_die("PTRACE_SETOPTIONS"); 2183 } 2184 } 2185 } 2186 } 2187 2188 sig = WSTOPSIG(status); 2189 2190 if (event != 0) { 2191 /* Ptrace event */ 2192#if USE_SEIZE 2193 if (event == PTRACE_EVENT_STOP) { 2194 /* 2195 * PTRACE_INTERRUPT-stop or group-stop. 2196 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here. 2197 */ 2198 if (sig == SIGSTOP 2199 || sig == SIGTSTP 2200 || sig == SIGTTIN 2201 || sig == SIGTTOU 2202 ) { 2203 stopped = 1; 2204 goto show_stopsig; 2205 } 2206 } 2207#endif 2208 goto restart_tracee_with_sig_0; 2209 } 2210 2211 /* Is this post-attach SIGSTOP? 2212 * Interestingly, the process may stop 2213 * with STOPSIG equal to some other signal 2214 * than SIGSTOP if we happend to attach 2215 * just before the process takes a signal. 2216 */ 2217 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) { 2218 if (debug_flag) 2219 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid); 2220 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP; 2221 goto restart_tracee_with_sig_0; 2222 } 2223 2224 if (sig != syscall_trap_sig) { 2225 siginfo_t si; 2226 2227 /* Nonzero (true) if tracee is stopped by signal 2228 * (as opposed to "tracee received signal"). 2229 * TODO: shouldn't we check for errno == EINVAL too? 2230 * We can get ESRCH instead, you know... 2231 */ 2232 stopped = (ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0); 2233#if USE_SEIZE 2234 show_stopsig: 2235#endif 2236 if (cflag != CFLAG_ONLY_STATS 2237 && !hide_log_until_execve 2238 && (qual_flags[sig] & QUAL_SIGNAL) 2239 ) { 2240#if defined(PT_CR_IPSR) && defined(PT_CR_IIP) 2241 long pc = 0; 2242 long psr = 0; 2243 2244 upeek(tcp, PT_CR_IPSR, &psr); 2245 upeek(tcp, PT_CR_IIP, &pc); 2246 2247# define PSR_RI 41 2248 pc += (psr >> PSR_RI) & 0x3; 2249# define PC_FORMAT_STR " @ %lx" 2250# define PC_FORMAT_ARG , pc 2251#else 2252# define PC_FORMAT_STR "" 2253# define PC_FORMAT_ARG /* nothing */ 2254#endif 2255 printleader(tcp); 2256 if (!stopped) { 2257 tprintf("--- %s ", signame(sig)); 2258 printsiginfo(&si, verbose(tcp)); 2259 tprintf(PC_FORMAT_STR " ---\n" 2260 PC_FORMAT_ARG); 2261 } else 2262 tprintf("--- stopped by %s" PC_FORMAT_STR " ---\n", 2263 signame(sig) 2264 PC_FORMAT_ARG); 2265 line_ended(); 2266 } 2267 2268 if (!stopped) 2269 /* It's signal-delivery-stop. Inject the signal */ 2270 goto restart_tracee; 2271 2272 /* It's group-stop */ 2273 if (use_seize) { 2274 /* 2275 * This ends ptrace-stop, but does *not* end group-stop. 2276 * This makes stopping signals work properly on straced process 2277 * (that is, process really stops. It used to continue to run). 2278 */ 2279 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) { 2280 cleanup(); 2281 return -1; 2282 } 2283 continue; 2284 } 2285 /* We don't have PTRACE_LISTEN support... */ 2286 goto restart_tracee; 2287 } 2288 2289 /* We handled quick cases, we are permitted to interrupt now. */ 2290 if (interrupted) 2291 return 0; 2292 2293 /* This should be syscall entry or exit. 2294 * (Or it still can be that pesky post-execve SIGTRAP!) 2295 * Handle it. 2296 */ 2297 if (trace_syscall(tcp) < 0) { 2298 /* ptrace() failed in trace_syscall(). 2299 * Likely a result of process disappearing mid-flight. 2300 * Observed case: exit_group() or SIGKILL terminating 2301 * all processes in thread group. 2302 * We assume that ptrace error was caused by process death. 2303 * We used to detach(tcp) here, but since we no longer 2304 * implement "detach before death" policy/hack, 2305 * we can let this process to report its death to us 2306 * normally, via WIFEXITED or WIFSIGNALED wait status. 2307 */ 2308 continue; 2309 } 2310 restart_tracee_with_sig_0: 2311 sig = 0; 2312 restart_tracee: 2313 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) { 2314 cleanup(); 2315 return -1; 2316 } 2317 } 2318 return 0; 2319} 2320 2321int 2322main(int argc, char *argv[]) 2323{ 2324 init(argc, argv); 2325 2326 /* Run main tracing loop */ 2327 if (trace() < 0) 2328 return 1; 2329 2330 cleanup(); 2331 fflush(NULL); 2332 if (shared_log != stderr) 2333 fclose(shared_log); 2334 if (popen_pid) { 2335 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR) 2336 ; 2337 } 2338 if (exit_code > 0xff) { 2339 /* Avoid potential core file clobbering. */ 2340 struct_rlimit rlim = {0, 0}; 2341 set_rlimit(RLIMIT_CORE, &rlim); 2342 2343 /* Child was killed by a signal, mimic that. */ 2344 exit_code &= 0xff; 2345 signal(exit_code, SIG_DFL); 2346 raise(exit_code); 2347 /* Paranoia - what if this signal is not fatal? 2348 Exit with 128 + signo then. */ 2349 exit_code += 128; 2350 } 2351 2352 return exit_code; 2353} 2354