strace.c revision fdfa47af7e05b320cc1c62fc5854ded781679917
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 void 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 void 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,%u)", tcp->pid); 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: tkill(%u,0)", tcp->pid); 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 else if (errno != ESRCH) 792 perror_msg("detach: ptrace(PTRACE_INTERRUPT,%u)", tcp->pid); 793 } 794 else { 795 error = my_tkill(tcp->pid, SIGSTOP); 796 if (!error) 797 sigstop_expected = 1; 798 else if (errno != ESRCH) 799 perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid); 800 } 801 } 802 } 803 804 if (sigstop_expected || interrupt_done) { 805 for (;;) { 806 int sig; 807 if (waitpid(tcp->pid, &status, __WALL) < 0) { 808 if (errno == EINTR) 809 continue; 810 /* 811 * if (errno == ECHILD) break; 812 * ^^^ WRONG! We expect this PID to exist, 813 * and want to emit a message otherwise: 814 */ 815 perror_msg("detach: waitpid(%u)", tcp->pid); 816 break; 817 } 818 if (!WIFSTOPPED(status)) { 819 /* 820 * Tracee exited or was killed by signal. 821 * We shouldn't normally reach this place: 822 * we don't want to consume exit status. 823 * Consider "strace -p PID" being ^C-ed: 824 * we want merely to detach from PID. 825 * 826 * However, we _can_ end up here if tracee 827 * was SIGKILLed. 828 */ 829 break; 830 } 831 sig = WSTOPSIG(status); 832 if (debug_flag) 833 fprintf(stderr, "detach wait: event:%d sig:%d\n", 834 (unsigned)status >> 16, sig); 835 if (sigstop_expected && sig == SIGSTOP) { 836 /* Detach, suppressing SIGSTOP */ 837 ptrace_restart(PTRACE_DETACH, tcp, 0); 838 break; 839 } 840 if (interrupt_done) { 841 unsigned event = (unsigned)status >> 16; 842 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) { 843 /* 844 * sig == SIGTRAP: PTRACE_INTERRUPT stop. 845 * sig == other: process was already stopped 846 * with this stopping sig (see tests/detach-stopped). 847 * Looks like re-injecting this sig is not necessary 848 * in DETACH for the tracee to remain stopped. 849 */ 850 sig = 0; 851 } 852 /* 853 * PTRACE_INTERRUPT is not guaranteed to produce 854 * the above event if other ptrace-stop is pending. 855 * See tests/detach-sleeping testcase: 856 * strace got SIGINT while tracee is sleeping. 857 * We sent PTRACE_INTERRUPT. 858 * We see syscall exit, not PTRACE_INTERRUPT stop. 859 * We won't get PTRACE_INTERRUPT stop 860 * if we would CONT now. Need to DETACH. 861 */ 862 if (sig == syscall_trap_sig) 863 sig = 0; 864 /* else: not sure in which case we can be here. 865 * Signal stop? Inject it while detaching. 866 */ 867 ptrace_restart(PTRACE_DETACH, tcp, sig); 868 break; 869 } 870 if (sig == syscall_trap_sig) 871 sig = 0; 872 /* Can't detach just yet, may need to wait for SIGSTOP */ 873 error = ptrace_restart(PTRACE_CONT, tcp, sig); 874 if (error < 0) { 875 /* Should not happen. 876 * Note: ptrace_restart returns 0 on ESRCH, so it's not it. 877 * ptrace_restart already emitted error message. 878 */ 879 break; 880 } 881 } 882 } 883 884 if (!qflag && (tcp->flags & TCB_ATTACHED)) 885 fprintf(stderr, "Process %u detached\n", tcp->pid); 886 887 droptcb(tcp); 888} 889 890static void 891process_opt_p_list(char *opt) 892{ 893 while (*opt) { 894 /* 895 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`". 896 * pidof uses space as delim, pgrep uses newline. :( 897 */ 898 int pid; 899 char *delim = opt + strcspn(opt, ", \n\t"); 900 char c = *delim; 901 902 *delim = '\0'; 903 pid = string_to_uint(opt); 904 if (pid <= 0) { 905 error_msg_and_die("Invalid process id: '%s'", opt); 906 } 907 if (pid == strace_tracer_pid) { 908 error_msg_and_die("I'm sorry, I can't let you do that, Dave."); 909 } 910 *delim = c; 911 alloctcb(pid); 912 if (c == '\0') 913 break; 914 opt = delim + 1; 915 } 916} 917 918static void 919startup_attach(void) 920{ 921 int tcbi; 922 struct tcb *tcp; 923 924 /* 925 * Block user interruptions as we would leave the traced 926 * process stopped (process state T) if we would terminate in 927 * between PTRACE_ATTACH and wait4() on SIGSTOP. 928 * We rely on cleanup() from this point on. 929 */ 930 if (interactive) 931 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 932 933 if (daemonized_tracer) { 934 pid_t pid = fork(); 935 if (pid < 0) { 936 perror_msg_and_die("fork"); 937 } 938 if (pid) { /* parent */ 939 /* 940 * Wait for grandchild to attach to straced process 941 * (grandparent). Grandchild SIGKILLs us after it attached. 942 * Grandparent's wait() is unblocked by our death, 943 * it proceeds to exec the straced program. 944 */ 945 pause(); 946 _exit(0); /* paranoia */ 947 } 948 /* grandchild */ 949 /* We will be the tracer process. Remember our new pid: */ 950 strace_tracer_pid = getpid(); 951 } 952 953 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) { 954 tcp = tcbtab[tcbi]; 955 956 if (!(tcp->flags & TCB_INUSE)) 957 continue; 958 959 /* Is this a process we should attach to, but not yet attached? */ 960 if (tcp->flags & TCB_ATTACHED) 961 continue; /* no, we already attached it */ 962 963 if (followfork && !daemonized_tracer) { 964 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3]; 965 DIR *dir; 966 967 sprintf(procdir, "/proc/%d/task", tcp->pid); 968 dir = opendir(procdir); 969 if (dir != NULL) { 970 unsigned int ntid = 0, nerr = 0; 971 struct_dirent *de; 972 973 while ((de = read_dir(dir)) != NULL) { 974 struct tcb *cur_tcp; 975 int tid; 976 977 if (de->d_fileno == 0) 978 continue; 979 /* we trust /proc filesystem */ 980 tid = atoi(de->d_name); 981 if (tid <= 0) 982 continue; 983 ++ntid; 984 if (ptrace_attach_or_seize(tid) < 0) { 985 ++nerr; 986 if (debug_flag) 987 fprintf(stderr, "attach to pid %d failed\n", tid); 988 continue; 989 } 990 if (debug_flag) 991 fprintf(stderr, "attach to pid %d succeeded\n", tid); 992 cur_tcp = tcp; 993 if (tid != tcp->pid) 994 cur_tcp = alloctcb(tid); 995 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 996 newoutf(cur_tcp); 997 } 998 closedir(dir); 999 if (interactive) { 1000 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1001 if (interrupted) 1002 goto ret; 1003 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1004 } 1005 ntid -= nerr; 1006 if (ntid == 0) { 1007 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1008 droptcb(tcp); 1009 continue; 1010 } 1011 if (!qflag) { 1012 fprintf(stderr, ntid > 1 1013? "Process %u attached with %u threads\n" 1014: "Process %u attached\n", 1015 tcp->pid, ntid); 1016 } 1017 if (!(tcp->flags & TCB_ATTACHED)) { 1018 /* -p PID, we failed to attach to PID itself 1019 * but did attach to some of its sibling threads. 1020 * Drop PID's tcp. 1021 */ 1022 droptcb(tcp); 1023 } 1024 continue; 1025 } /* if (opendir worked) */ 1026 } /* if (-f) */ 1027 if (ptrace_attach_or_seize(tcp->pid) < 0) { 1028 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1029 droptcb(tcp); 1030 continue; 1031 } 1032 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1033 newoutf(tcp); 1034 if (debug_flag) 1035 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid); 1036 1037 if (daemonized_tracer) { 1038 /* 1039 * Make parent go away. 1040 * Also makes grandparent's wait() unblock. 1041 */ 1042 kill(getppid(), SIGKILL); 1043 } 1044 1045 if (!qflag) 1046 fprintf(stderr, 1047 "Process %u attached\n", 1048 tcp->pid); 1049 } /* for each tcbtab[] */ 1050 1051 ret: 1052 if (interactive) 1053 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1054} 1055 1056/* Stack-o-phobic exec helper, in the hope to work around 1057 * NOMMU + "daemonized tracer" difficulty. 1058 */ 1059struct exec_params { 1060 int fd_to_close; 1061 uid_t run_euid; 1062 gid_t run_egid; 1063 char **argv; 1064 char *pathname; 1065}; 1066static struct exec_params params_for_tracee; 1067static void __attribute__ ((noinline, noreturn)) 1068exec_or_die(void) 1069{ 1070 struct exec_params *params = ¶ms_for_tracee; 1071 1072 if (params->fd_to_close >= 0) 1073 close(params->fd_to_close); 1074 if (!daemonized_tracer && !use_seize) { 1075 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) { 1076 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)"); 1077 } 1078 } 1079 1080 if (username != NULL) { 1081 /* 1082 * It is important to set groups before we 1083 * lose privileges on setuid. 1084 */ 1085 if (initgroups(username, run_gid) < 0) { 1086 perror_msg_and_die("initgroups"); 1087 } 1088 if (setregid(run_gid, params->run_egid) < 0) { 1089 perror_msg_and_die("setregid"); 1090 } 1091 if (setreuid(run_uid, params->run_euid) < 0) { 1092 perror_msg_and_die("setreuid"); 1093 } 1094 } 1095 else if (geteuid() != 0) 1096 if (setreuid(run_uid, run_uid) < 0) { 1097 perror_msg_and_die("setreuid"); 1098 } 1099 1100 if (!daemonized_tracer) { 1101 /* 1102 * Induce a ptrace stop. Tracer (our parent) 1103 * will resume us with PTRACE_SYSCALL and display 1104 * the immediately following execve syscall. 1105 * Can't do this on NOMMU systems, we are after 1106 * vfork: parent is blocked, stopping would deadlock. 1107 */ 1108 if (!NOMMU_SYSTEM) 1109 kill(getpid(), SIGSTOP); 1110 } else { 1111 alarm(3); 1112 /* we depend on SIGCHLD set to SIG_DFL by init code */ 1113 /* if it happens to be SIG_IGN'ed, wait won't block */ 1114 wait(NULL); 1115 alarm(0); 1116 } 1117 1118 execv(params->pathname, params->argv); 1119 perror_msg_and_die("exec"); 1120} 1121 1122static void 1123startup_child(char **argv) 1124{ 1125 struct_stat statbuf; 1126 const char *filename; 1127 char pathname[MAXPATHLEN]; 1128 int pid; 1129 struct tcb *tcp; 1130 1131 filename = argv[0]; 1132 if (strchr(filename, '/')) { 1133 if (strlen(filename) > sizeof pathname - 1) { 1134 errno = ENAMETOOLONG; 1135 perror_msg_and_die("exec"); 1136 } 1137 strcpy(pathname, filename); 1138 } 1139#ifdef USE_DEBUGGING_EXEC 1140 /* 1141 * Debuggers customarily check the current directory 1142 * first regardless of the path but doing that gives 1143 * security geeks a panic attack. 1144 */ 1145 else if (stat_file(filename, &statbuf) == 0) 1146 strcpy(pathname, filename); 1147#endif /* USE_DEBUGGING_EXEC */ 1148 else { 1149 const char *path; 1150 int m, n, len; 1151 1152 for (path = getenv("PATH"); path && *path; path += m) { 1153 const char *colon = strchr(path, ':'); 1154 if (colon) { 1155 n = colon - path; 1156 m = n + 1; 1157 } 1158 else 1159 m = n = strlen(path); 1160 if (n == 0) { 1161 if (!getcwd(pathname, MAXPATHLEN)) 1162 continue; 1163 len = strlen(pathname); 1164 } 1165 else if (n > sizeof pathname - 1) 1166 continue; 1167 else { 1168 strncpy(pathname, path, n); 1169 len = n; 1170 } 1171 if (len && pathname[len - 1] != '/') 1172 pathname[len++] = '/'; 1173 strcpy(pathname + len, filename); 1174 if (stat_file(pathname, &statbuf) == 0 && 1175 /* Accept only regular files 1176 with some execute bits set. 1177 XXX not perfect, might still fail */ 1178 S_ISREG(statbuf.st_mode) && 1179 (statbuf.st_mode & 0111)) 1180 break; 1181 } 1182 } 1183 if (stat_file(pathname, &statbuf) < 0) { 1184 perror_msg_and_die("Can't stat '%s'", filename); 1185 } 1186 1187 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1; 1188 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid; 1189 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid; 1190 params_for_tracee.argv = argv; 1191 /* 1192 * On NOMMU, can be safely freed only after execve in tracee. 1193 * It's hard to know when that happens, so we just leak it. 1194 */ 1195 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname; 1196 1197#if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY 1198 if (daemonized_tracer) 1199 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY); 1200#endif 1201 1202 strace_child = pid = fork(); 1203 if (pid < 0) { 1204 perror_msg_and_die("fork"); 1205 } 1206 if ((pid != 0 && daemonized_tracer) 1207 || (pid == 0 && !daemonized_tracer) 1208 ) { 1209 /* We are to become the tracee. Two cases: 1210 * -D: we are parent 1211 * not -D: we are child 1212 */ 1213 exec_or_die(); 1214 } 1215 1216 /* We are the tracer */ 1217 1218 if (!daemonized_tracer) { 1219 if (!use_seize) { 1220 /* child did PTRACE_TRACEME, nothing to do in parent */ 1221 } else { 1222 if (!NOMMU_SYSTEM) { 1223 /* Wait until child stopped itself */ 1224 int status; 1225 while (waitpid(pid, &status, WSTOPPED) < 0) { 1226 if (errno == EINTR) 1227 continue; 1228 perror_msg_and_die("waitpid"); 1229 } 1230 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) { 1231 kill_save_errno(pid, SIGKILL); 1232 perror_msg_and_die("Unexpected wait status %x", status); 1233 } 1234 } 1235 /* Else: NOMMU case, we have no way to sync. 1236 * Just attach to it as soon as possible. 1237 * This means that we may miss a few first syscalls... 1238 */ 1239 1240 if (ptrace_attach_or_seize(pid)) { 1241 kill_save_errno(pid, SIGKILL); 1242 perror_msg_and_die("Can't attach to %d", pid); 1243 } 1244 if (!NOMMU_SYSTEM) 1245 kill(pid, SIGCONT); 1246 } 1247 tcp = alloctcb(pid); 1248 if (!NOMMU_SYSTEM) 1249 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP | post_attach_sigstop; 1250 else 1251 tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP; 1252 newoutf(tcp); 1253 } 1254 else { 1255 /* With -D, we are *child* here, IOW: different pid. Fetch it: */ 1256 strace_tracer_pid = getpid(); 1257 /* The tracee is our parent: */ 1258 pid = getppid(); 1259 alloctcb(pid); 1260 /* attaching will be done later, by startup_attach */ 1261 /* note: we don't do newoutf(tcp) here either! */ 1262 1263 /* NOMMU BUG! -D mode is active, we (child) return, 1264 * and we will scribble over parent's stack! 1265 * When parent later unpauses, it segfaults. 1266 * 1267 * We work around it 1268 * (1) by declaring exec_or_die() NORETURN, 1269 * hopefully compiler will just jump to it 1270 * instead of call (won't push anything to stack), 1271 * (2) by trying very hard in exec_or_die() 1272 * to not use any stack, 1273 * (3) having a really big (MAXPATHLEN) stack object 1274 * in this function, which creates a "buffer" between 1275 * child's and parent's stack pointers. 1276 * This may save us if (1) and (2) failed 1277 * and compiler decided to use stack in exec_or_die() anyway 1278 * (happens on i386 because of stack parameter passing). 1279 * 1280 * A cleaner solution is to use makecontext + setcontext 1281 * to create a genuine separate stack and execute on it. 1282 */ 1283 } 1284} 1285 1286/* 1287 * Test whether the kernel support PTRACE_O_TRACECLONE et al options. 1288 * First fork a new child, call ptrace with PTRACE_SETOPTIONS on it, 1289 * and then see which options are supported by the kernel. 1290 */ 1291static int 1292test_ptrace_setoptions_followfork(void) 1293{ 1294 int pid, expected_grandchild = 0, found_grandchild = 0; 1295 const unsigned int test_options = PTRACE_O_TRACECLONE | 1296 PTRACE_O_TRACEFORK | 1297 PTRACE_O_TRACEVFORK; 1298 1299 /* Need fork for test. NOMMU has no forks */ 1300 if (NOMMU_SYSTEM) 1301 goto worked; /* be bold, and pretend that test succeeded */ 1302 1303 pid = fork(); 1304 if (pid < 0) 1305 perror_msg_and_die("fork"); 1306 if (pid == 0) { 1307 pid = getpid(); 1308 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1309 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1310 __func__); 1311 kill_save_errno(pid, SIGSTOP); 1312 if (fork() < 0) 1313 perror_msg_and_die("fork"); 1314 _exit(0); 1315 } 1316 1317 while (1) { 1318 int status, tracee_pid; 1319 1320 errno = 0; 1321 tracee_pid = wait(&status); 1322 if (tracee_pid <= 0) { 1323 if (errno == EINTR) 1324 continue; 1325 if (errno == ECHILD) 1326 break; 1327 kill_save_errno(pid, SIGKILL); 1328 perror_msg_and_die("%s: unexpected wait result %d", 1329 __func__, tracee_pid); 1330 } 1331 if (WIFEXITED(status)) { 1332 if (WEXITSTATUS(status)) { 1333 if (tracee_pid != pid) 1334 kill_save_errno(pid, SIGKILL); 1335 error_msg_and_die("%s: unexpected exit status %u", 1336 __func__, WEXITSTATUS(status)); 1337 } 1338 continue; 1339 } 1340 if (WIFSIGNALED(status)) { 1341 if (tracee_pid != pid) 1342 kill_save_errno(pid, SIGKILL); 1343 error_msg_and_die("%s: unexpected signal %u", 1344 __func__, WTERMSIG(status)); 1345 } 1346 if (!WIFSTOPPED(status)) { 1347 if (tracee_pid != pid) 1348 kill_save_errno(tracee_pid, SIGKILL); 1349 kill_save_errno(pid, SIGKILL); 1350 error_msg_and_die("%s: unexpected wait status %x", 1351 __func__, status); 1352 } 1353 if (tracee_pid != pid) { 1354 found_grandchild = tracee_pid; 1355 if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0) { 1356 kill_save_errno(tracee_pid, SIGKILL); 1357 kill_save_errno(pid, SIGKILL); 1358 perror_msg_and_die("PTRACE_CONT doesn't work"); 1359 } 1360 continue; 1361 } 1362 switch (WSTOPSIG(status)) { 1363 case SIGSTOP: 1364 if (ptrace(PTRACE_SETOPTIONS, pid, 0, test_options) < 0 1365 && errno != EINVAL && errno != EIO) 1366 perror_msg("PTRACE_SETOPTIONS"); 1367 break; 1368 case SIGTRAP: 1369 if (status >> 16 == PTRACE_EVENT_FORK) { 1370 long msg = 0; 1371 1372 if (ptrace(PTRACE_GETEVENTMSG, pid, 1373 NULL, (long) &msg) == 0) 1374 expected_grandchild = msg; 1375 } 1376 break; 1377 } 1378 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) { 1379 kill_save_errno(pid, SIGKILL); 1380 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1381 } 1382 } 1383 if (expected_grandchild && expected_grandchild == found_grandchild) { 1384 worked: 1385 ptrace_setoptions |= test_options; 1386 if (debug_flag) 1387 fprintf(stderr, "ptrace_setoptions = %#x\n", 1388 ptrace_setoptions); 1389 return 0; 1390 } 1391 error_msg("Test for PTRACE_O_TRACECLONE failed, " 1392 "giving up using this feature."); 1393 return 1; 1394} 1395 1396/* 1397 * Test whether the kernel support PTRACE_O_TRACESYSGOOD. 1398 * First fork a new child, call ptrace(PTRACE_SETOPTIONS) on it, 1399 * and then see whether it will stop with (SIGTRAP | 0x80). 1400 * 1401 * Use of this option enables correct handling of user-generated SIGTRAPs, 1402 * and SIGTRAPs generated by special instructions such as int3 on x86: 1403 * _start: .globl _start 1404 * int3 1405 * movl $42, %ebx 1406 * movl $1, %eax 1407 * int $0x80 1408 * (compile with: "gcc -nostartfiles -nostdlib -o int3 int3.S") 1409 */ 1410static int 1411test_ptrace_setoptions_for_all(void) 1412{ 1413 const unsigned int test_options = PTRACE_O_TRACESYSGOOD | 1414 PTRACE_O_TRACEEXEC; 1415 int pid; 1416 int it_worked = 0; 1417 1418 /* Need fork for test. NOMMU has no forks */ 1419 if (NOMMU_SYSTEM) 1420 goto worked; /* be bold, and pretend that test succeeded */ 1421 1422 pid = fork(); 1423 if (pid < 0) 1424 perror_msg_and_die("fork"); 1425 1426 if (pid == 0) { 1427 pid = getpid(); 1428 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1429 /* Note: exits with exitcode 1 */ 1430 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1431 __func__); 1432 kill(pid, SIGSTOP); 1433 _exit(0); /* parent should see entry into this syscall */ 1434 } 1435 1436 while (1) { 1437 int status, tracee_pid; 1438 1439 errno = 0; 1440 tracee_pid = wait(&status); 1441 if (tracee_pid <= 0) { 1442 if (errno == EINTR) 1443 continue; 1444 kill_save_errno(pid, SIGKILL); 1445 perror_msg_and_die("%s: unexpected wait result %d", 1446 __func__, tracee_pid); 1447 } 1448 if (WIFEXITED(status)) { 1449 if (WEXITSTATUS(status) == 0) 1450 break; 1451 error_msg_and_die("%s: unexpected exit status %u", 1452 __func__, WEXITSTATUS(status)); 1453 } 1454 if (WIFSIGNALED(status)) { 1455 error_msg_and_die("%s: unexpected signal %u", 1456 __func__, WTERMSIG(status)); 1457 } 1458 if (!WIFSTOPPED(status)) { 1459 kill(pid, SIGKILL); 1460 error_msg_and_die("%s: unexpected wait status %x", 1461 __func__, status); 1462 } 1463 if (WSTOPSIG(status) == SIGSTOP) { 1464 /* 1465 * We don't check "options aren't accepted" error. 1466 * If it happens, we'll never get (SIGTRAP | 0x80), 1467 * and thus will decide to not use the option. 1468 * IOW: the outcome of the test will be correct. 1469 */ 1470 if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0 1471 && errno != EINVAL && errno != EIO) 1472 perror_msg("PTRACE_SETOPTIONS"); 1473 } 1474 if (WSTOPSIG(status) == (SIGTRAP | 0x80)) { 1475 it_worked = 1; 1476 } 1477 if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) { 1478 kill_save_errno(pid, SIGKILL); 1479 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1480 } 1481 } 1482 1483 if (it_worked) { 1484 worked: 1485 syscall_trap_sig = (SIGTRAP | 0x80); 1486 ptrace_setoptions |= test_options; 1487 if (debug_flag) 1488 fprintf(stderr, "ptrace_setoptions = %#x\n", 1489 ptrace_setoptions); 1490 return 0; 1491 } 1492 1493 error_msg("Test for PTRACE_O_TRACESYSGOOD failed, " 1494 "giving up using this feature."); 1495 return 1; 1496} 1497 1498#if USE_SEIZE 1499static void 1500test_ptrace_seize(void) 1501{ 1502 int pid; 1503 1504 /* Need fork for test. NOMMU has no forks */ 1505 if (NOMMU_SYSTEM) { 1506 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1507 return; 1508 } 1509 1510 pid = fork(); 1511 if (pid < 0) 1512 perror_msg_and_die("fork"); 1513 1514 if (pid == 0) { 1515 pause(); 1516 _exit(0); 1517 } 1518 1519 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After 1520 * attaching tracee continues to run unless a trap condition occurs. 1521 * PTRACE_SEIZE doesn't affect signal or group stop state. 1522 */ 1523 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) { 1524 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1525 } else if (debug_flag) { 1526 fprintf(stderr, "PTRACE_SEIZE doesn't work\n"); 1527 } 1528 1529 kill(pid, SIGKILL); 1530 1531 while (1) { 1532 int status, tracee_pid; 1533 1534 errno = 0; 1535 tracee_pid = waitpid(pid, &status, 0); 1536 if (tracee_pid <= 0) { 1537 if (errno == EINTR) 1538 continue; 1539 perror_msg_and_die("%s: unexpected wait result %d", 1540 __func__, tracee_pid); 1541 } 1542 if (WIFSIGNALED(status)) { 1543 return; 1544 } 1545 error_msg_and_die("%s: unexpected wait status %x", 1546 __func__, status); 1547 } 1548} 1549#else /* !USE_SEIZE */ 1550# define test_ptrace_seize() ((void)0) 1551#endif 1552 1553static unsigned 1554get_os_release(void) 1555{ 1556 unsigned rel; 1557 const char *p; 1558 struct utsname u; 1559 if (uname(&u) < 0) 1560 perror_msg_and_die("uname"); 1561 /* u.release has this form: "3.2.9[-some-garbage]" */ 1562 rel = 0; 1563 p = u.release; 1564 for (;;) { 1565 if (!(*p >= '0' && *p <= '9')) 1566 error_msg_and_die("Bad OS release string: '%s'", u.release); 1567 /* Note: this open-codes KERNEL_VERSION(): */ 1568 rel = (rel << 8) | atoi(p); 1569 if (rel >= KERNEL_VERSION(1,0,0)) 1570 break; 1571 while (*p >= '0' && *p <= '9') 1572 p++; 1573 if (*p != '.') { 1574 if (rel >= KERNEL_VERSION(0,1,0)) { 1575 /* "X.Y-something" means "X.Y.0" */ 1576 rel <<= 8; 1577 break; 1578 } 1579 error_msg_and_die("Bad OS release string: '%s'", u.release); 1580 } 1581 p++; 1582 } 1583 return rel; 1584} 1585 1586/* 1587 * Initialization part of main() was eating much stack (~0.5k), 1588 * which was unused after init. 1589 * We can reuse it if we move init code into a separate function. 1590 * 1591 * Don't want main() to inline us and defeat the reason 1592 * we have a separate function. 1593 */ 1594static void __attribute__ ((noinline)) 1595init(int argc, char *argv[]) 1596{ 1597 struct tcb *tcp; 1598 int c, i; 1599 int optF = 0; 1600 struct sigaction sa; 1601 1602 progname = argv[0] ? argv[0] : "strace"; 1603 1604 /* Make sure SIGCHLD has the default action so that waitpid 1605 definitely works without losing track of children. The user 1606 should not have given us a bogus state to inherit, but he might 1607 have. Arguably we should detect SIG_IGN here and pass it on 1608 to children, but probably noone really needs that. */ 1609 signal(SIGCHLD, SIG_DFL); 1610 1611 strace_tracer_pid = getpid(); 1612 1613 os_release = get_os_release(); 1614 1615 /* Allocate the initial tcbtab. */ 1616 tcbtabsize = argc; /* Surely enough for all -p args. */ 1617 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0])); 1618 if (!tcbtab) 1619 die_out_of_memory(); 1620 tcp = calloc(tcbtabsize, sizeof(*tcp)); 1621 if (!tcp) 1622 die_out_of_memory(); 1623 for (c = 0; c < tcbtabsize; c++) 1624 tcbtab[c] = tcp++; 1625 1626 shared_log = stderr; 1627 set_sortby(DEFAULT_SORTBY); 1628 set_personality(DEFAULT_PERSONALITY); 1629 qualify("trace=all"); 1630 qualify("abbrev=all"); 1631 qualify("verbose=all"); 1632#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE) 1633# error Bug in DEFAULT_QUAL_FLAGS 1634#endif 1635 qualify("signal=all"); 1636 while ((c = getopt(argc, argv, 1637 "+b:cCdfFhiqrtTvVxyz" 1638 "D" 1639 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) { 1640 switch (c) { 1641 case 'b': 1642 if (strcmp(optarg, "execve") != 0) 1643 error_msg_and_die("Syscall '%s' for -b isn't supported", 1644 optarg); 1645 detach_on_execve = 1; 1646 break; 1647 case 'c': 1648 if (cflag == CFLAG_BOTH) { 1649 error_msg_and_die("-c and -C are mutually exclusive"); 1650 } 1651 cflag = CFLAG_ONLY_STATS; 1652 break; 1653 case 'C': 1654 if (cflag == CFLAG_ONLY_STATS) { 1655 error_msg_and_die("-c and -C are mutually exclusive"); 1656 } 1657 cflag = CFLAG_BOTH; 1658 break; 1659 case 'd': 1660 debug_flag = 1; 1661 break; 1662 case 'D': 1663 daemonized_tracer = 1; 1664 break; 1665 case 'F': 1666 optF = 1; 1667 break; 1668 case 'f': 1669 followfork++; 1670 break; 1671 case 'h': 1672 usage(stdout, 0); 1673 break; 1674 case 'i': 1675 iflag = 1; 1676 break; 1677 case 'q': 1678 qflag++; 1679 break; 1680 case 'r': 1681 rflag = 1; 1682 /* fall through to tflag++ */ 1683 case 't': 1684 tflag++; 1685 break; 1686 case 'T': 1687 Tflag = 1; 1688 break; 1689 case 'x': 1690 xflag++; 1691 break; 1692 case 'y': 1693 show_fd_path = 1; 1694 break; 1695 case 'v': 1696 qualify("abbrev=none"); 1697 break; 1698 case 'V': 1699 printf("%s -- version %s\n", PACKAGE_NAME, VERSION); 1700 exit(0); 1701 break; 1702 case 'z': 1703 not_failing_only = 1; 1704 break; 1705 case 'a': 1706 acolumn = string_to_uint(optarg); 1707 if (acolumn < 0) 1708 error_opt_arg(c, optarg); 1709 break; 1710 case 'e': 1711 qualify(optarg); 1712 break; 1713 case 'o': 1714 outfname = strdup(optarg); 1715 break; 1716 case 'O': 1717 i = string_to_uint(optarg); 1718 if (i < 0) 1719 error_opt_arg(c, optarg); 1720 set_overhead(i); 1721 break; 1722 case 'p': 1723 process_opt_p_list(optarg); 1724 break; 1725 case 'P': 1726 pathtrace_select(optarg); 1727 break; 1728 case 's': 1729 i = string_to_uint(optarg); 1730 if (i < 0) 1731 error_opt_arg(c, optarg); 1732 max_strlen = i; 1733 break; 1734 case 'S': 1735 set_sortby(optarg); 1736 break; 1737 case 'u': 1738 username = strdup(optarg); 1739 break; 1740 case 'E': 1741 if (putenv(optarg) < 0) 1742 die_out_of_memory(); 1743 break; 1744 case 'I': 1745 opt_intr = string_to_uint(optarg); 1746 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS) 1747 error_opt_arg(c, optarg); 1748 break; 1749 default: 1750 usage(stderr, 1); 1751 break; 1752 } 1753 } 1754 argv += optind; 1755 /* argc -= optind; - no need, argc is not used below */ 1756 1757 acolumn_spaces = malloc(acolumn + 1); 1758 if (!acolumn_spaces) 1759 die_out_of_memory(); 1760 memset(acolumn_spaces, ' ', acolumn); 1761 acolumn_spaces[acolumn] = '\0'; 1762 1763 /* Must have PROG [ARGS], or -p PID. Not both. */ 1764 if (!argv[0] == !nprocs) 1765 usage(stderr, 1); 1766 1767 if (nprocs != 0 && daemonized_tracer) { 1768 error_msg_and_die("-D and -p are mutually exclusive"); 1769 } 1770 1771 if (!followfork) 1772 followfork = optF; 1773 1774 if (followfork >= 2 && cflag) { 1775 error_msg_and_die("(-c or -C) and -ff are mutually exclusive"); 1776 } 1777 1778 /* See if they want to run as another user. */ 1779 if (username != NULL) { 1780 struct passwd *pent; 1781 1782 if (getuid() != 0 || geteuid() != 0) { 1783 error_msg_and_die("You must be root to use the -u option"); 1784 } 1785 pent = getpwnam(username); 1786 if (pent == NULL) { 1787 error_msg_and_die("Cannot find user '%s'", username); 1788 } 1789 run_uid = pent->pw_uid; 1790 run_gid = pent->pw_gid; 1791 } 1792 else { 1793 run_uid = getuid(); 1794 run_gid = getgid(); 1795 } 1796 1797 /* 1798 * On any reasonably recent Linux kernel (circa about 2.5.46) 1799 * need_fork_exec_workarounds should stay 0 after these tests: 1800 */ 1801 /*need_fork_exec_workarounds = 0; - already is */ 1802 if (followfork) 1803 need_fork_exec_workarounds = test_ptrace_setoptions_followfork(); 1804 need_fork_exec_workarounds |= test_ptrace_setoptions_for_all(); 1805 test_ptrace_seize(); 1806 1807 /* Check if they want to redirect the output. */ 1808 if (outfname) { 1809 /* See if they want to pipe the output. */ 1810 if (outfname[0] == '|' || outfname[0] == '!') { 1811 /* 1812 * We can't do the <outfname>.PID funny business 1813 * when using popen, so prohibit it. 1814 */ 1815 if (followfork >= 2) 1816 error_msg_and_die("Piping the output and -ff are mutually exclusive"); 1817 shared_log = strace_popen(outfname + 1); 1818 } 1819 else if (followfork < 2) 1820 shared_log = strace_fopen(outfname); 1821 } else { 1822 /* -ff without -o FILE is the same as single -f */ 1823 if (followfork >= 2) 1824 followfork = 1; 1825 } 1826 1827 if (!outfname || outfname[0] == '|' || outfname[0] == '!') { 1828 char *buf = malloc(BUFSIZ); 1829 if (!buf) 1830 die_out_of_memory(); 1831 setvbuf(shared_log, buf, _IOLBF, BUFSIZ); 1832 } 1833 if (outfname && argv[0]) { 1834 if (!opt_intr) 1835 opt_intr = INTR_NEVER; 1836 qflag = 1; 1837 } 1838 if (!opt_intr) 1839 opt_intr = INTR_WHILE_WAIT; 1840 1841 /* argv[0] -pPID -oFILE Default interactive setting 1842 * yes 0 0 INTR_WHILE_WAIT 1843 * no 1 0 INTR_WHILE_WAIT 1844 * yes 0 1 INTR_NEVER 1845 * no 1 1 INTR_WHILE_WAIT 1846 */ 1847 1848 sigemptyset(&empty_set); 1849 sigemptyset(&blocked_set); 1850 1851 /* startup_child() must be called before the signal handlers get 1852 * installed below as they are inherited into the spawned process. 1853 * Also we do not need to be protected by them as during interruption 1854 * in the startup_child() mode we kill the spawned process anyway. 1855 */ 1856 if (argv[0]) { 1857 if (!NOMMU_SYSTEM || daemonized_tracer) 1858 hide_log_until_execve = 1; 1859 skip_one_b_execve = 1; 1860 startup_child(argv); 1861 } 1862 1863 sa.sa_handler = SIG_IGN; 1864 sigemptyset(&sa.sa_mask); 1865 sa.sa_flags = 0; 1866 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */ 1867 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */ 1868 if (opt_intr != INTR_ANYWHERE) { 1869 if (opt_intr == INTR_BLOCK_TSTP_TOO) 1870 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */ 1871 /* 1872 * In interactive mode (if no -o OUTFILE, or -p PID is used), 1873 * fatal signals are blocked while syscall stop is processed, 1874 * and acted on in between, when waiting for new syscall stops. 1875 * In non-interactive mode, signals are ignored. 1876 */ 1877 if (opt_intr == INTR_WHILE_WAIT) { 1878 sigaddset(&blocked_set, SIGHUP); 1879 sigaddset(&blocked_set, SIGINT); 1880 sigaddset(&blocked_set, SIGQUIT); 1881 sigaddset(&blocked_set, SIGPIPE); 1882 sigaddset(&blocked_set, SIGTERM); 1883 sa.sa_handler = interrupt; 1884 } 1885 /* SIG_IGN, or set handler for these */ 1886 sigaction(SIGHUP, &sa, NULL); 1887 sigaction(SIGINT, &sa, NULL); 1888 sigaction(SIGQUIT, &sa, NULL); 1889 sigaction(SIGPIPE, &sa, NULL); 1890 sigaction(SIGTERM, &sa, NULL); 1891 } 1892 if (nprocs != 0 || daemonized_tracer) 1893 startup_attach(); 1894 1895 /* Do we want pids printed in our -o OUTFILE? 1896 * -ff: no (every pid has its own file); or 1897 * -f: yes (there can be more pids in the future); or 1898 * -p PID1,PID2: yes (there are already more than one pid) 1899 */ 1900 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1)); 1901} 1902 1903static struct tcb * 1904pid2tcb(int pid) 1905{ 1906 int i; 1907 1908 if (pid <= 0) 1909 return NULL; 1910 1911 for (i = 0; i < tcbtabsize; i++) { 1912 struct tcb *tcp = tcbtab[i]; 1913 if (tcp->pid == pid && (tcp->flags & TCB_INUSE)) 1914 return tcp; 1915 } 1916 1917 return NULL; 1918} 1919 1920static void 1921cleanup(void) 1922{ 1923 int i; 1924 struct tcb *tcp; 1925 int fatal_sig; 1926 1927 /* 'interrupted' is a volatile object, fetch it only once */ 1928 fatal_sig = interrupted; 1929 if (!fatal_sig) 1930 fatal_sig = SIGTERM; 1931 1932 for (i = 0; i < tcbtabsize; i++) { 1933 tcp = tcbtab[i]; 1934 if (!(tcp->flags & TCB_INUSE)) 1935 continue; 1936 if (debug_flag) 1937 fprintf(stderr, 1938 "cleanup: looking at pid %u\n", tcp->pid); 1939 if (tcp->flags & TCB_STRACE_CHILD) { 1940 kill(tcp->pid, SIGCONT); 1941 kill(tcp->pid, fatal_sig); 1942 } 1943 detach(tcp); 1944 } 1945 if (cflag) 1946 call_summary(shared_log); 1947} 1948 1949static void 1950interrupt(int sig) 1951{ 1952 interrupted = sig; 1953} 1954 1955static int 1956trace(void) 1957{ 1958 struct rusage ru; 1959 1960 while (nprocs != 0) { 1961 int pid; 1962 int wait_errno; 1963 int status, sig; 1964 int stopped; 1965 struct tcb *tcp; 1966 unsigned event; 1967 1968 if (interrupted) 1969 return 0; 1970 1971 if (interactive) 1972 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1973 pid = wait4(-1, &status, __WALL, (cflag ? &ru : NULL)); 1974 wait_errno = errno; 1975 if (interactive) 1976 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1977 1978 if (pid < 0) { 1979 if (wait_errno == EINTR) 1980 continue; 1981 if (wait_errno == ECHILD) 1982 /* Should not happen since nprocs > 0 */ 1983 return 0; 1984 errno = wait_errno; 1985 perror_msg("wait4(__WALL)"); 1986 return -1; 1987 } 1988 1989 if (pid == popen_pid) { 1990 if (WIFEXITED(status) || WIFSIGNALED(status)) 1991 popen_pid = 0; 1992 continue; 1993 } 1994 1995 event = ((unsigned)status >> 16); 1996 if (debug_flag) { 1997 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16]; 1998 char evbuf[sizeof(",PTRACE_EVENT_?? (%u)") + sizeof(int)*3 /*paranoia:*/ + 16]; 1999 strcpy(buf, "???"); 2000 if (WIFSIGNALED(status)) 2001#ifdef WCOREDUMP 2002 sprintf(buf, "WIFSIGNALED,%ssig=%s", 2003 WCOREDUMP(status) ? "core," : "", 2004 signame(WTERMSIG(status))); 2005#else 2006 sprintf(buf, "WIFSIGNALED,sig=%s", 2007 signame(WTERMSIG(status))); 2008#endif 2009 if (WIFEXITED(status)) 2010 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status)); 2011 if (WIFSTOPPED(status)) 2012 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status))); 2013#ifdef WIFCONTINUED 2014 if (WIFCONTINUED(status)) 2015 strcpy(buf, "WIFCONTINUED"); 2016#endif 2017 evbuf[0] = '\0'; 2018 if (event != 0) { 2019 static const char *const event_names[] = { 2020 [PTRACE_EVENT_CLONE] = "CLONE", 2021 [PTRACE_EVENT_FORK] = "FORK", 2022 [PTRACE_EVENT_VFORK] = "VFORK", 2023 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE", 2024 [PTRACE_EVENT_EXEC] = "EXEC", 2025 [PTRACE_EVENT_EXIT] = "EXIT", 2026 }; 2027 const char *e; 2028 if (event < ARRAY_SIZE(event_names)) 2029 e = event_names[event]; 2030 else { 2031 sprintf(buf, "?? (%u)", event); 2032 e = buf; 2033 } 2034 sprintf(evbuf, ",PTRACE_EVENT_%s", e); 2035 } 2036 fprintf(stderr, " [wait(0x%04x) = %u] %s%s\n", status, pid, buf, evbuf); 2037 } 2038 2039 /* Look up 'pid' in our table. */ 2040 tcp = pid2tcb(pid); 2041 2042 if (!tcp) { 2043 if (followfork) { 2044 tcp = alloctcb(pid); 2045 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 2046 newoutf(tcp); 2047 if (!qflag) 2048 fprintf(stderr, "Process %d attached\n", 2049 pid); 2050 } else { 2051 /* This can happen if a clone call used 2052 CLONE_PTRACE itself. */ 2053 if (WIFSTOPPED(status)) 2054 ptrace(PTRACE_CONT, pid, (char *) 0, 0); 2055 error_msg_and_die("Unknown pid: %u", pid); 2056 } 2057 } 2058 2059 clear_regs(); 2060 if (WIFSTOPPED(status)) 2061 get_regs(pid); 2062 2063 /* Under Linux, execve changes pid to thread leader's pid, 2064 * and we see this changed pid on EVENT_EXEC and later, 2065 * execve sysexit. Leader "disappears" without exit 2066 * notification. Let user know that, drop leader's tcb, 2067 * and fix up pid in execve thread's tcb. 2068 * Effectively, execve thread's tcb replaces leader's tcb. 2069 * 2070 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED 2071 * on exit syscall) in multithreaded programs exactly 2072 * in order to handle this case. 2073 * 2074 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0. 2075 * On 2.6 and earlier, it can return garbage. 2076 */ 2077 if (event == PTRACE_EVENT_EXEC && os_release >= KERNEL_VERSION(3,0,0)) { 2078 FILE *fp; 2079 struct tcb *execve_thread; 2080 long old_pid = 0; 2081 2082 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0) 2083 goto dont_switch_tcbs; 2084 if (old_pid <= 0 || old_pid == pid) 2085 goto dont_switch_tcbs; 2086 execve_thread = pid2tcb(old_pid); 2087 /* It should be !NULL, but I feel paranoid */ 2088 if (!execve_thread) 2089 goto dont_switch_tcbs; 2090 2091 if (execve_thread->curcol != 0) { 2092 /* 2093 * One case we are here is -ff: 2094 * try "strace -oLOG -ff test/threaded_execve" 2095 */ 2096 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid); 2097 /*execve_thread->curcol = 0; - no need, see code below */ 2098 } 2099 /* Swap output FILEs (needed for -ff) */ 2100 fp = execve_thread->outf; 2101 execve_thread->outf = tcp->outf; 2102 tcp->outf = fp; 2103 /* And their column positions */ 2104 execve_thread->curcol = tcp->curcol; 2105 tcp->curcol = 0; 2106 /* Drop leader, but close execve'd thread outfile (if -ff) */ 2107 droptcb(tcp); 2108 /* Switch to the thread, reusing leader's outfile and pid */ 2109 tcp = execve_thread; 2110 tcp->pid = pid; 2111 if (cflag != CFLAG_ONLY_STATS) { 2112 printleader(tcp); 2113 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid); 2114 line_ended(); 2115 tcp->flags |= TCB_REPRINT; 2116 } 2117 } 2118 dont_switch_tcbs: 2119 2120 if (event == PTRACE_EVENT_EXEC) { 2121 if (detach_on_execve && !skip_one_b_execve) 2122 detach(tcp); /* do "-b execve" thingy */ 2123 skip_one_b_execve = 0; 2124 } 2125 2126 /* Set current output file */ 2127 current_tcp = tcp; 2128 2129 if (cflag) { 2130 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime); 2131 tcp->stime = ru.ru_stime; 2132 } 2133 2134 if (WIFSIGNALED(status)) { 2135 if (pid == strace_child) 2136 exit_code = 0x100 | WTERMSIG(status); 2137 if (cflag != CFLAG_ONLY_STATS 2138 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL) 2139 ) { 2140 printleader(tcp); 2141#ifdef WCOREDUMP 2142 tprintf("+++ killed by %s %s+++\n", 2143 signame(WTERMSIG(status)), 2144 WCOREDUMP(status) ? "(core dumped) " : ""); 2145#else 2146 tprintf("+++ killed by %s +++\n", 2147 signame(WTERMSIG(status))); 2148#endif 2149 line_ended(); 2150 } 2151 droptcb(tcp); 2152 continue; 2153 } 2154 if (WIFEXITED(status)) { 2155 if (pid == strace_child) 2156 exit_code = WEXITSTATUS(status); 2157 if (cflag != CFLAG_ONLY_STATS && 2158 qflag < 2) { 2159 printleader(tcp); 2160 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status)); 2161 line_ended(); 2162 } 2163 droptcb(tcp); 2164 continue; 2165 } 2166 if (!WIFSTOPPED(status)) { 2167 fprintf(stderr, "PANIC: pid %u not stopped\n", pid); 2168 droptcb(tcp); 2169 continue; 2170 } 2171 2172 /* Is this the very first time we see this tracee stopped? */ 2173 if (tcp->flags & TCB_STARTUP) { 2174 if (debug_flag) 2175 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n", tcp->pid); 2176 tcp->flags &= ~TCB_STARTUP; 2177 if (tcp->flags & TCB_BPTSET) { 2178 /* 2179 * One example is a breakpoint inherited from 2180 * parent through fork(). 2181 */ 2182 if (clearbpt(tcp) < 0) { 2183 /* Pretty fatal */ 2184 droptcb(tcp); 2185 cleanup(); 2186 return -1; 2187 } 2188 } 2189 if (ptrace_setoptions) { 2190 if (debug_flag) 2191 fprintf(stderr, "setting opts %x on pid %d\n", ptrace_setoptions, tcp->pid); 2192 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) { 2193 if (errno != ESRCH) { 2194 /* Should never happen, really */ 2195 perror_msg_and_die("PTRACE_SETOPTIONS"); 2196 } 2197 } 2198 } 2199 } 2200 2201 sig = WSTOPSIG(status); 2202 2203 if (event != 0) { 2204 /* Ptrace event */ 2205#if USE_SEIZE 2206 if (event == PTRACE_EVENT_STOP) { 2207 /* 2208 * PTRACE_INTERRUPT-stop or group-stop. 2209 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here. 2210 */ 2211 if (sig == SIGSTOP 2212 || sig == SIGTSTP 2213 || sig == SIGTTIN 2214 || sig == SIGTTOU 2215 ) { 2216 stopped = 1; 2217 goto show_stopsig; 2218 } 2219 } 2220#endif 2221 goto restart_tracee_with_sig_0; 2222 } 2223 2224 /* Is this post-attach SIGSTOP? 2225 * Interestingly, the process may stop 2226 * with STOPSIG equal to some other signal 2227 * than SIGSTOP if we happend to attach 2228 * just before the process takes a signal. 2229 */ 2230 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) { 2231 if (debug_flag) 2232 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid); 2233 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP; 2234 goto restart_tracee_with_sig_0; 2235 } 2236 2237 if (sig != syscall_trap_sig) { 2238 siginfo_t si; 2239 2240 /* Nonzero (true) if tracee is stopped by signal 2241 * (as opposed to "tracee received signal"). 2242 * TODO: shouldn't we check for errno == EINVAL too? 2243 * We can get ESRCH instead, you know... 2244 */ 2245 stopped = (ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0); 2246#if USE_SEIZE 2247 show_stopsig: 2248#endif 2249 if (cflag != CFLAG_ONLY_STATS 2250 && !hide_log_until_execve 2251 && (qual_flags[sig] & QUAL_SIGNAL) 2252 ) { 2253#if defined(PT_CR_IPSR) && defined(PT_CR_IIP) 2254 long pc = 0; 2255 long psr = 0; 2256 2257 upeek(tcp, PT_CR_IPSR, &psr); 2258 upeek(tcp, PT_CR_IIP, &pc); 2259 2260# define PSR_RI 41 2261 pc += (psr >> PSR_RI) & 0x3; 2262# define PC_FORMAT_STR " @ %lx" 2263# define PC_FORMAT_ARG , pc 2264#else 2265# define PC_FORMAT_STR "" 2266# define PC_FORMAT_ARG /* nothing */ 2267#endif 2268 printleader(tcp); 2269 if (!stopped) { 2270 tprintf("--- %s ", signame(sig)); 2271 printsiginfo(&si, verbose(tcp)); 2272 tprintf(PC_FORMAT_STR " ---\n" 2273 PC_FORMAT_ARG); 2274 } else 2275 tprintf("--- stopped by %s" PC_FORMAT_STR " ---\n", 2276 signame(sig) 2277 PC_FORMAT_ARG); 2278 line_ended(); 2279 } 2280 2281 if (!stopped) 2282 /* It's signal-delivery-stop. Inject the signal */ 2283 goto restart_tracee; 2284 2285 /* It's group-stop */ 2286 if (use_seize) { 2287 /* 2288 * This ends ptrace-stop, but does *not* end group-stop. 2289 * This makes stopping signals work properly on straced process 2290 * (that is, process really stops. It used to continue to run). 2291 */ 2292 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) { 2293 cleanup(); 2294 return -1; 2295 } 2296 continue; 2297 } 2298 /* We don't have PTRACE_LISTEN support... */ 2299 goto restart_tracee; 2300 } 2301 2302 /* We handled quick cases, we are permitted to interrupt now. */ 2303 if (interrupted) 2304 return 0; 2305 2306 /* This should be syscall entry or exit. 2307 * (Or it still can be that pesky post-execve SIGTRAP!) 2308 * Handle it. 2309 */ 2310 if (trace_syscall(tcp) < 0) { 2311 /* ptrace() failed in trace_syscall(). 2312 * Likely a result of process disappearing mid-flight. 2313 * Observed case: exit_group() or SIGKILL terminating 2314 * all processes in thread group. 2315 * We assume that ptrace error was caused by process death. 2316 * We used to detach(tcp) here, but since we no longer 2317 * implement "detach before death" policy/hack, 2318 * we can let this process to report its death to us 2319 * normally, via WIFEXITED or WIFSIGNALED wait status. 2320 */ 2321 continue; 2322 } 2323 restart_tracee_with_sig_0: 2324 sig = 0; 2325 restart_tracee: 2326 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) { 2327 cleanup(); 2328 return -1; 2329 } 2330 } 2331 return 0; 2332} 2333 2334int 2335main(int argc, char *argv[]) 2336{ 2337 init(argc, argv); 2338 2339 /* Run main tracing loop */ 2340 if (trace() < 0) 2341 return 1; 2342 2343 cleanup(); 2344 fflush(NULL); 2345 if (shared_log != stderr) 2346 fclose(shared_log); 2347 if (popen_pid) { 2348 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR) 2349 ; 2350 } 2351 if (exit_code > 0xff) { 2352 /* Avoid potential core file clobbering. */ 2353 struct_rlimit rlim = {0, 0}; 2354 set_rlimit(RLIMIT_CORE, &rlim); 2355 2356 /* Child was killed by a signal, mimic that. */ 2357 exit_code &= 0xff; 2358 signal(exit_code, SIG_DFL); 2359 raise(exit_code); 2360 /* Paranoia - what if this signal is not fatal? 2361 Exit with 128 + signo then. */ 2362 exit_code += 128; 2363 } 2364 2365 return exit_code; 2366} 2367