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#ifdef USE_LIBUNWIND 54/* if this is true do the stack trace for every system call */ 55bool stack_trace_enabled = false; 56#endif 57 58#if defined __NR_tkill 59# define my_tkill(tid, sig) syscall(__NR_tkill, (tid), (sig)) 60#else 61 /* kill() may choose arbitrarily the target task of the process group 62 while we later wait on a that specific TID. PID process waits become 63 TID task specific waits for a process under ptrace(2). */ 64# warning "tkill(2) not available, risk of strace hangs!" 65# define my_tkill(tid, sig) kill((tid), (sig)) 66#endif 67 68/* Glue for systems without a MMU that cannot provide fork() */ 69#if !defined(HAVE_FORK) 70# undef NOMMU_SYSTEM 71# define NOMMU_SYSTEM 1 72#endif 73#if NOMMU_SYSTEM 74# define fork() vfork() 75#endif 76 77cflag_t cflag = CFLAG_NONE; 78unsigned int followfork = 0; 79unsigned int ptrace_setoptions = 0; 80unsigned int xflag = 0; 81bool need_fork_exec_workarounds = 0; 82bool debug_flag = 0; 83bool Tflag = 0; 84bool iflag = 0; 85bool count_wallclock = 0; 86unsigned int qflag = 0; 87/* Which WSTOPSIG(status) value marks syscall traps? */ 88static unsigned int syscall_trap_sig = SIGTRAP; 89static unsigned int tflag = 0; 90static bool rflag = 0; 91static bool print_pid_pfx = 0; 92 93/* -I n */ 94enum { 95 INTR_NOT_SET = 0, 96 INTR_ANYWHERE = 1, /* don't block/ignore any signals */ 97 INTR_WHILE_WAIT = 2, /* block fatal signals while decoding syscall. default */ 98 INTR_NEVER = 3, /* block fatal signals. default if '-o FILE PROG' */ 99 INTR_BLOCK_TSTP_TOO = 4, /* block fatal signals and SIGTSTP (^Z) */ 100 NUM_INTR_OPTS 101}; 102static int opt_intr; 103/* We play with signal mask only if this mode is active: */ 104#define interactive (opt_intr == INTR_WHILE_WAIT) 105 106/* 107 * daemonized_tracer supports -D option. 108 * With this option, strace forks twice. 109 * Unlike normal case, with -D *grandparent* process exec's, 110 * becoming a traced process. Child exits (this prevents traced process 111 * from having children it doesn't expect to have), and grandchild 112 * attaches to grandparent similarly to strace -p PID. 113 * This allows for more transparent interaction in cases 114 * when process and its parent are communicating via signals, 115 * wait() etc. Without -D, strace process gets lodged in between, 116 * disrupting parent<->child link. 117 */ 118static bool daemonized_tracer = 0; 119 120#if USE_SEIZE 121static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP; 122# define use_seize (post_attach_sigstop == 0) 123#else 124# define post_attach_sigstop TCB_IGNORE_ONE_SIGSTOP 125# define use_seize 0 126#endif 127 128/* Sometimes we want to print only succeeding syscalls. */ 129bool not_failing_only = 0; 130 131/* Show path associated with fd arguments */ 132bool show_fd_path = 0; 133 134static bool detach_on_execve = 0; 135/* Are we "strace PROG" and need to skip detach on first execve? */ 136static bool skip_one_b_execve = 0; 137/* Are we "strace PROG" and need to hide everything until execve? */ 138bool hide_log_until_execve = 0; 139 140static int exit_code = 0; 141static int strace_child = 0; 142static int strace_tracer_pid = 0; 143 144static char *username = NULL; 145static uid_t run_uid; 146static gid_t run_gid; 147 148unsigned int max_strlen = DEFAULT_STRLEN; 149static int acolumn = DEFAULT_ACOLUMN; 150static char *acolumn_spaces; 151 152static char *outfname = NULL; 153/* If -ff, points to stderr. Else, it's our common output log */ 154static FILE *shared_log; 155 156struct tcb *printing_tcp = NULL; 157static struct tcb *current_tcp; 158 159static struct tcb **tcbtab; 160static unsigned int nprocs, tcbtabsize; 161static const char *progname; 162 163unsigned os_release; /* generated from uname()'s u.release */ 164 165static void detach(struct tcb *tcp); 166static void cleanup(void); 167static void interrupt(int sig); 168static sigset_t empty_set, blocked_set; 169 170#ifdef HAVE_SIG_ATOMIC_T 171static volatile sig_atomic_t interrupted; 172#else 173static volatile int interrupted; 174#endif 175 176#ifndef HAVE_STRERROR 177 178#if !HAVE_DECL_SYS_ERRLIST 179extern int sys_nerr; 180extern char *sys_errlist[]; 181#endif 182 183const char * 184strerror(int err_no) 185{ 186 static char buf[sizeof("Unknown error %d") + sizeof(int)*3]; 187 188 if (err_no < 1 || err_no >= sys_nerr) { 189 sprintf(buf, "Unknown error %d", err_no); 190 return buf; 191 } 192 return sys_errlist[err_no]; 193} 194 195#endif /* HAVE_STERRROR */ 196 197static void 198usage(FILE *ofp, int exitval) 199{ 200 fprintf(ofp, "\ 201usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\ 202 [-a column] [-o file] [-s strsize] [-P path]...\n\ 203 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 204 or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\ 205 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 206-c -- count time, calls, and errors for each syscall and report summary\n\ 207-C -- like -c but also print regular output\n\ 208-w -- summarise syscall latency (default is system time)\n\ 209-d -- enable debug output to stderr\n\ 210-D -- run tracer process as a detached grandchild, not as parent\n\ 211-f -- follow forks, -ff -- with output into separate files\n\ 212-i -- print instruction pointer at time of syscall\n\ 213-q -- suppress messages about attaching, detaching, etc.\n\ 214-r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs\n\ 215-T -- print time spent in each syscall\n\ 216-v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\ 217-x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\ 218-y -- print paths associated with file descriptor arguments\n\ 219-h -- print help message, -V -- print version\n\ 220-a column -- alignment COLUMN for printing syscall results (default %d)\n\ 221-b execve -- detach on this syscall\n\ 222-e expr -- a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\ 223 options: trace, abbrev, verbose, raw, signal, read, write\n\ 224-I interruptible --\n\ 225 1: no signals are blocked\n\ 226 2: fatal signals are blocked while decoding syscall (default)\n\ 227 3: fatal signals are always blocked (default if '-o FILE PROG')\n\ 228 4: fatal signals and SIGTSTP (^Z) are always blocked\n\ 229 (useful to make 'strace -o FILE PROG' not stop on ^Z)\n\ 230-o file -- send trace output to FILE instead of stderr\n\ 231-O overhead -- set overhead for tracing syscalls to OVERHEAD usecs\n\ 232-p pid -- trace process with process id PID, may be repeated\n\ 233-s strsize -- limit length of print strings to STRSIZE chars (default %d)\n\ 234-S sortby -- sort syscall counts by: time, calls, name, nothing (default %s)\n\ 235-u username -- run command as username handling setuid and/or setgid\n\ 236-E var=val -- put var=val in the environment for command\n\ 237-E var -- remove var from the environment for command\n\ 238-P path -- trace accesses to path\n\ 239" 240#ifdef USE_LIBUNWIND 241"-k obtain stack trace between each syscall (experimental)\n\ 242" 243#endif 244/* ancient, no one should use it 245-F -- attempt to follow vforks (deprecated, use -f)\n\ 246 */ 247/* this is broken, so don't document it 248-z -- print only succeeding syscalls\n\ 249 */ 250, DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY); 251 exit(exitval); 252} 253 254static void die(void) __attribute__ ((noreturn)); 255static void die(void) 256{ 257 if (strace_tracer_pid == getpid()) { 258 cflag = 0; 259 cleanup(); 260 } 261 exit(1); 262} 263 264static void verror_msg(int err_no, const char *fmt, va_list p) 265{ 266 char *msg; 267 268 fflush(NULL); 269 270 /* We want to print entire message with single fprintf to ensure 271 * message integrity if stderr is shared with other programs. 272 * Thus we use vasprintf + single fprintf. 273 */ 274 msg = NULL; 275 if (vasprintf(&msg, fmt, p) >= 0) { 276 if (err_no) 277 fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no)); 278 else 279 fprintf(stderr, "%s: %s\n", progname, msg); 280 free(msg); 281 } else { 282 /* malloc in vasprintf failed, try it without malloc */ 283 fprintf(stderr, "%s: ", progname); 284 vfprintf(stderr, fmt, p); 285 if (err_no) 286 fprintf(stderr, ": %s\n", strerror(err_no)); 287 else 288 putc('\n', stderr); 289 } 290 /* We don't switch stderr to buffered, thus fprintf(stderr) 291 * always flushes its output and this is not necessary: */ 292 /* fflush(stderr); */ 293} 294 295void error_msg(const char *fmt, ...) 296{ 297 va_list p; 298 va_start(p, fmt); 299 verror_msg(0, fmt, p); 300 va_end(p); 301} 302 303void error_msg_and_die(const char *fmt, ...) 304{ 305 va_list p; 306 va_start(p, fmt); 307 verror_msg(0, fmt, p); 308 die(); 309} 310 311void perror_msg(const char *fmt, ...) 312{ 313 va_list p; 314 va_start(p, fmt); 315 verror_msg(errno, fmt, p); 316 va_end(p); 317} 318 319void perror_msg_and_die(const char *fmt, ...) 320{ 321 va_list p; 322 va_start(p, fmt); 323 verror_msg(errno, fmt, p); 324 die(); 325} 326 327void die_out_of_memory(void) 328{ 329 static bool recursed = 0; 330 if (recursed) 331 exit(1); 332 recursed = 1; 333 error_msg_and_die("Out of memory"); 334} 335 336static void 337error_opt_arg(int opt, const char *arg) 338{ 339 error_msg_and_die("Invalid -%c argument: '%s'", opt, arg); 340} 341 342#if USE_SEIZE 343static int 344ptrace_attach_or_seize(int pid) 345{ 346 int r; 347 if (!use_seize) 348 return ptrace(PTRACE_ATTACH, pid, 0L, 0L); 349 r = ptrace(PTRACE_SEIZE, pid, 0L, (unsigned long)ptrace_setoptions); 350 if (r) 351 return r; 352 r = ptrace(PTRACE_INTERRUPT, pid, 0L, 0L); 353 return r; 354} 355#else 356# define ptrace_attach_or_seize(pid) ptrace(PTRACE_ATTACH, (pid), 0, 0) 357#endif 358 359/* 360 * Used when we want to unblock stopped traced process. 361 * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL. 362 * Returns 0 on success or if error was ESRCH 363 * (presumably process was killed while we talk to it). 364 * Otherwise prints error message and returns -1. 365 */ 366static int 367ptrace_restart(int op, struct tcb *tcp, int sig) 368{ 369 int err; 370 const char *msg; 371 372 errno = 0; 373 ptrace(op, tcp->pid, (void *) 0, (long) sig); 374 err = errno; 375 if (!err) 376 return 0; 377 378 msg = "SYSCALL"; 379 if (op == PTRACE_CONT) 380 msg = "CONT"; 381 if (op == PTRACE_DETACH) 382 msg = "DETACH"; 383#ifdef PTRACE_LISTEN 384 if (op == PTRACE_LISTEN) 385 msg = "LISTEN"; 386#endif 387 /* 388 * Why curcol != 0? Otherwise sometimes we get this: 389 * 390 * 10252 kill(10253, SIGKILL) = 0 391 * <ptrace(SYSCALL,10252):No such process>10253 ...next decode... 392 * 393 * 10252 died after we retrieved syscall exit data, 394 * but before we tried to restart it. Log looks ugly. 395 */ 396 if (current_tcp && current_tcp->curcol != 0) { 397 tprintf(" <ptrace(%s):%s>\n", msg, strerror(err)); 398 line_ended(); 399 } 400 if (err == ESRCH) 401 return 0; 402 errno = err; 403 perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig); 404 return -1; 405} 406 407static void 408set_cloexec_flag(int fd) 409{ 410 int flags, newflags; 411 412 flags = fcntl(fd, F_GETFD); 413 if (flags < 0) { 414 /* Can happen only if fd is bad. 415 * Should never happen: if it does, we have a bug 416 * in the caller. Therefore we just abort 417 * instead of propagating the error. 418 */ 419 perror_msg_and_die("fcntl(%d, F_GETFD)", fd); 420 } 421 422 newflags = flags | FD_CLOEXEC; 423 if (flags == newflags) 424 return; 425 426 fcntl(fd, F_SETFD, newflags); /* never fails */ 427} 428 429static void kill_save_errno(pid_t pid, int sig) 430{ 431 int saved_errno = errno; 432 433 (void) kill(pid, sig); 434 errno = saved_errno; 435} 436 437/* 438 * When strace is setuid executable, we have to swap uids 439 * before and after filesystem and process management operations. 440 */ 441static void 442swap_uid(void) 443{ 444 int euid = geteuid(), uid = getuid(); 445 446 if (euid != uid && setreuid(euid, uid) < 0) { 447 perror_msg_and_die("setreuid"); 448 } 449} 450 451#ifdef _LARGEFILE64_SOURCE 452# ifdef HAVE_FOPEN64 453# define fopen_for_output fopen64 454# else 455# define fopen_for_output fopen 456# endif 457# define struct_stat struct stat64 458# define stat_file stat64 459# define struct_dirent struct dirent64 460# define read_dir readdir64 461# define struct_rlimit struct rlimit64 462# define set_rlimit setrlimit64 463#else 464# define fopen_for_output fopen 465# define struct_stat struct stat 466# define stat_file stat 467# define struct_dirent struct dirent 468# define read_dir readdir 469# define struct_rlimit struct rlimit 470# define set_rlimit setrlimit 471#endif 472 473static FILE * 474strace_fopen(const char *path) 475{ 476 FILE *fp; 477 478 swap_uid(); 479 fp = fopen_for_output(path, "w"); 480 if (!fp) 481 perror_msg_and_die("Can't fopen '%s'", path); 482 swap_uid(); 483 set_cloexec_flag(fileno(fp)); 484 return fp; 485} 486 487static int popen_pid = 0; 488 489#ifndef _PATH_BSHELL 490# define _PATH_BSHELL "/bin/sh" 491#endif 492 493/* 494 * We cannot use standard popen(3) here because we have to distinguish 495 * popen child process from other processes we trace, and standard popen(3) 496 * does not export its child's pid. 497 */ 498static FILE * 499strace_popen(const char *command) 500{ 501 FILE *fp; 502 int pid; 503 int fds[2]; 504 505 swap_uid(); 506 if (pipe(fds) < 0) 507 perror_msg_and_die("pipe"); 508 509 set_cloexec_flag(fds[1]); /* never fails */ 510 511 pid = vfork(); 512 if (pid < 0) 513 perror_msg_and_die("vfork"); 514 515 if (pid == 0) { 516 /* child */ 517 close(fds[1]); 518 if (fds[0] != 0) { 519 if (dup2(fds[0], 0)) 520 perror_msg_and_die("dup2"); 521 close(fds[0]); 522 } 523 execl(_PATH_BSHELL, "sh", "-c", command, NULL); 524 perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL); 525 } 526 527 /* parent */ 528 popen_pid = pid; 529 close(fds[0]); 530 swap_uid(); 531 fp = fdopen(fds[1], "w"); 532 if (!fp) 533 die_out_of_memory(); 534 return fp; 535} 536 537void 538tprintf(const char *fmt, ...) 539{ 540 va_list args; 541 542 va_start(args, fmt); 543 if (current_tcp) { 544 int n = strace_vfprintf(current_tcp->outf, fmt, args); 545 if (n < 0) { 546 if (current_tcp->outf != stderr) 547 perror_msg("%s", outfname); 548 } else 549 current_tcp->curcol += n; 550 } 551 va_end(args); 552} 553 554#ifndef HAVE_FPUTS_UNLOCKED 555# define fputs_unlocked fputs 556#endif 557 558void 559tprints(const char *str) 560{ 561 if (current_tcp) { 562 int n = fputs_unlocked(str, current_tcp->outf); 563 if (n >= 0) { 564 current_tcp->curcol += strlen(str); 565 return; 566 } 567 if (current_tcp->outf != stderr) 568 perror_msg("%s", outfname); 569 } 570} 571 572void 573line_ended(void) 574{ 575 if (current_tcp) { 576 current_tcp->curcol = 0; 577 fflush(current_tcp->outf); 578 } 579 if (printing_tcp) { 580 printing_tcp->curcol = 0; 581 printing_tcp = NULL; 582 } 583} 584 585void 586printleader(struct tcb *tcp) 587{ 588 /* If -ff, "previous tcb we printed" is always the same as current, 589 * because we have per-tcb output files. 590 */ 591 if (followfork >= 2) 592 printing_tcp = tcp; 593 594 if (printing_tcp) { 595 current_tcp = printing_tcp; 596 if (printing_tcp->curcol != 0 && (followfork < 2 || printing_tcp == tcp)) { 597 /* 598 * case 1: we have a shared log (i.e. not -ff), and last line 599 * wasn't finished (same or different tcb, doesn't matter). 600 * case 2: split log, we are the same tcb, but our last line 601 * didn't finish ("SIGKILL nuked us after syscall entry" etc). 602 */ 603 tprints(" <unfinished ...>\n"); 604 printing_tcp->curcol = 0; 605 } 606 } 607 608 printing_tcp = tcp; 609 current_tcp = tcp; 610 current_tcp->curcol = 0; 611 612 if (print_pid_pfx) 613 tprintf("%-5d ", tcp->pid); 614 else if (nprocs > 1 && !outfname) 615 tprintf("[pid %5u] ", tcp->pid); 616 617 if (tflag) { 618 char str[sizeof("HH:MM:SS")]; 619 struct timeval tv, dtv; 620 static struct timeval otv; 621 622 gettimeofday(&tv, NULL); 623 if (rflag) { 624 if (otv.tv_sec == 0) 625 otv = tv; 626 tv_sub(&dtv, &tv, &otv); 627 tprintf("%6ld.%06ld ", 628 (long) dtv.tv_sec, (long) dtv.tv_usec); 629 otv = tv; 630 } 631 else if (tflag > 2) { 632 tprintf("%ld.%06ld ", 633 (long) tv.tv_sec, (long) tv.tv_usec); 634 } 635 else { 636 time_t local = tv.tv_sec; 637 strftime(str, sizeof(str), "%T", localtime(&local)); 638 if (tflag > 1) 639 tprintf("%s.%06ld ", str, (long) tv.tv_usec); 640 else 641 tprintf("%s ", str); 642 } 643 } 644 if (iflag) 645 print_pc(tcp); 646} 647 648void 649tabto(void) 650{ 651 if (current_tcp->curcol < acolumn) 652 tprints(acolumn_spaces + current_tcp->curcol); 653} 654 655/* Should be only called directly *after successful attach* to a tracee. 656 * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>" 657 * may create bogus empty FILE.<nonexistant_pid>, and then die. 658 */ 659static void 660newoutf(struct tcb *tcp) 661{ 662 tcp->outf = shared_log; /* if not -ff mode, the same file is for all */ 663 if (followfork >= 2) { 664 char name[520 + sizeof(int) * 3]; 665 sprintf(name, "%.512s.%u", outfname, tcp->pid); 666 tcp->outf = strace_fopen(name); 667 } 668} 669 670static void 671expand_tcbtab(void) 672{ 673 /* Allocate some more TCBs and expand the table. 674 We don't want to relocate the TCBs because our 675 callers have pointers and it would be a pain. 676 So tcbtab is a table of pointers. Since we never 677 free the TCBs, we allocate a single chunk of many. */ 678 int i = tcbtabsize; 679 struct tcb *newtcbs = calloc(tcbtabsize, sizeof(newtcbs[0])); 680 struct tcb **newtab = realloc(tcbtab, tcbtabsize * 2 * sizeof(tcbtab[0])); 681 if (!newtab || !newtcbs) 682 die_out_of_memory(); 683 tcbtabsize *= 2; 684 tcbtab = newtab; 685 while (i < tcbtabsize) 686 tcbtab[i++] = newtcbs++; 687} 688 689static struct tcb * 690alloctcb(int pid) 691{ 692 int i; 693 struct tcb *tcp; 694 695 if (nprocs == tcbtabsize) 696 expand_tcbtab(); 697 698 for (i = 0; i < tcbtabsize; i++) { 699 tcp = tcbtab[i]; 700 if (!tcp->pid) { 701 memset(tcp, 0, sizeof(*tcp)); 702 tcp->pid = pid; 703#if SUPPORTED_PERSONALITIES > 1 704 tcp->currpers = current_personality; 705#endif 706 707#ifdef USE_LIBUNWIND 708 if (stack_trace_enabled) 709 unwind_tcb_init(tcp); 710#endif 711 712 nprocs++; 713 if (debug_flag) 714 fprintf(stderr, "new tcb for pid %d, active tcbs:%d\n", tcp->pid, nprocs); 715 return tcp; 716 } 717 } 718 error_msg_and_die("bug in alloctcb"); 719} 720 721static void 722droptcb(struct tcb *tcp) 723{ 724 if (tcp->pid == 0) 725 return; 726 727#ifdef USE_LIBUNWIND 728 if (stack_trace_enabled) { 729 unwind_tcb_fin(tcp); 730 } 731#endif 732 733 nprocs--; 734 if (debug_flag) 735 fprintf(stderr, "dropped tcb for pid %d, %d remain\n", tcp->pid, nprocs); 736 737 if (tcp->outf) { 738 if (followfork >= 2) { 739 if (tcp->curcol != 0) 740 fprintf(tcp->outf, " <detached ...>\n"); 741 fclose(tcp->outf); 742 } else { 743 if (printing_tcp == tcp && tcp->curcol != 0) 744 fprintf(tcp->outf, " <detached ...>\n"); 745 fflush(tcp->outf); 746 } 747 } 748 749 if (current_tcp == tcp) 750 current_tcp = NULL; 751 if (printing_tcp == tcp) 752 printing_tcp = NULL; 753 754 memset(tcp, 0, sizeof(*tcp)); 755} 756 757/* Detach traced process. 758 * Never call DETACH twice on the same process as both unattached and 759 * attached-unstopped processes give the same ESRCH. For unattached process we 760 * would SIGSTOP it and wait for its SIGSTOP notification forever. 761 */ 762static void 763detach(struct tcb *tcp) 764{ 765 int error; 766 int status; 767 768 if (tcp->flags & TCB_BPTSET) 769 clearbpt(tcp); 770 771 /* 772 * Linux wrongly insists the child be stopped 773 * before detaching. Arghh. We go through hoops 774 * to make a clean break of things. 775 */ 776#if defined(SPARC) 777# undef PTRACE_DETACH 778# define PTRACE_DETACH PTRACE_SUNDETACH 779#endif 780 781 if (!(tcp->flags & TCB_ATTACHED)) 782 goto drop; 783 784 /* We attached but possibly didn't see the expected SIGSTOP. 785 * We must catch exactly one as otherwise the detached process 786 * would be left stopped (process state T). 787 */ 788 if (tcp->flags & TCB_IGNORE_ONE_SIGSTOP) 789 goto wait_loop; 790 791 error = ptrace(PTRACE_DETACH, tcp->pid, 0, 0); 792 if (!error) { 793 /* On a clear day, you can see forever. */ 794 goto drop; 795 } 796 if (errno != ESRCH) { 797 /* Shouldn't happen. */ 798 perror_msg("detach: ptrace(PTRACE_DETACH,%u)", tcp->pid); 799 goto drop; 800 } 801 /* ESRCH: process is either not stopped or doesn't exist. */ 802 if (my_tkill(tcp->pid, 0) < 0) { 803 if (errno != ESRCH) 804 /* Shouldn't happen. */ 805 perror_msg("detach: tkill(%u,0)", tcp->pid); 806 /* else: process doesn't exist. */ 807 goto drop; 808 } 809 /* Process is not stopped, need to stop it. */ 810 if (use_seize) { 811 /* 812 * With SEIZE, tracee can be in group-stop already. 813 * In this state sending it another SIGSTOP does nothing. 814 * Need to use INTERRUPT. 815 * Testcase: trying to ^C a "strace -p <stopped_process>". 816 */ 817 error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0); 818 if (!error) 819 goto wait_loop; 820 if (errno != ESRCH) 821 perror_msg("detach: ptrace(PTRACE_INTERRUPT,%u)", tcp->pid); 822 } 823 else { 824 error = my_tkill(tcp->pid, SIGSTOP); 825 if (!error) 826 goto wait_loop; 827 if (errno != ESRCH) 828 perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid); 829 } 830 /* Either process doesn't exist, or some weird error. */ 831 goto drop; 832 833 wait_loop: 834 /* We end up here in three cases: 835 * 1. We sent PTRACE_INTERRUPT (use_seize case) 836 * 2. We sent SIGSTOP (!use_seize) 837 * 3. Attach SIGSTOP was already pending (TCB_IGNORE_ONE_SIGSTOP set) 838 */ 839 for (;;) { 840 int sig; 841 if (waitpid(tcp->pid, &status, __WALL) < 0) { 842 if (errno == EINTR) 843 continue; 844 /* 845 * if (errno == ECHILD) break; 846 * ^^^ WRONG! We expect this PID to exist, 847 * and want to emit a message otherwise: 848 */ 849 perror_msg("detach: waitpid(%u)", tcp->pid); 850 break; 851 } 852 if (!WIFSTOPPED(status)) { 853 /* 854 * Tracee exited or was killed by signal. 855 * We shouldn't normally reach this place: 856 * we don't want to consume exit status. 857 * Consider "strace -p PID" being ^C-ed: 858 * we want merely to detach from PID. 859 * 860 * However, we _can_ end up here if tracee 861 * was SIGKILLed. 862 */ 863 break; 864 } 865 sig = WSTOPSIG(status); 866 if (debug_flag) 867 fprintf(stderr, "detach wait: event:%d sig:%d\n", 868 (unsigned)status >> 16, sig); 869 if (use_seize) { 870 unsigned event = (unsigned)status >> 16; 871 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) { 872 /* 873 * sig == SIGTRAP: PTRACE_INTERRUPT stop. 874 * sig == other: process was already stopped 875 * with this stopping sig (see tests/detach-stopped). 876 * Looks like re-injecting this sig is not necessary 877 * in DETACH for the tracee to remain stopped. 878 */ 879 sig = 0; 880 } 881 /* 882 * PTRACE_INTERRUPT is not guaranteed to produce 883 * the above event if other ptrace-stop is pending. 884 * See tests/detach-sleeping testcase: 885 * strace got SIGINT while tracee is sleeping. 886 * We sent PTRACE_INTERRUPT. 887 * We see syscall exit, not PTRACE_INTERRUPT stop. 888 * We won't get PTRACE_INTERRUPT stop 889 * if we would CONT now. Need to DETACH. 890 */ 891 if (sig == syscall_trap_sig) 892 sig = 0; 893 /* else: not sure in which case we can be here. 894 * Signal stop? Inject it while detaching. 895 */ 896 ptrace_restart(PTRACE_DETACH, tcp, sig); 897 break; 898 } 899 /* Note: this check has to be after use_seize check */ 900 /* (else, in use_seize case SIGSTOP will be mistreated) */ 901 if (sig == SIGSTOP) { 902 /* Detach, suppressing SIGSTOP */ 903 ptrace_restart(PTRACE_DETACH, tcp, 0); 904 break; 905 } 906 if (sig == syscall_trap_sig) 907 sig = 0; 908 /* Can't detach just yet, may need to wait for SIGSTOP */ 909 error = ptrace_restart(PTRACE_CONT, tcp, sig); 910 if (error < 0) { 911 /* Should not happen. 912 * Note: ptrace_restart returns 0 on ESRCH, so it's not it. 913 * ptrace_restart already emitted error message. 914 */ 915 break; 916 } 917 } 918 919 drop: 920 if (!qflag && (tcp->flags & TCB_ATTACHED)) 921 fprintf(stderr, "Process %u detached\n", tcp->pid); 922 923 droptcb(tcp); 924} 925 926static void 927process_opt_p_list(char *opt) 928{ 929 while (*opt) { 930 /* 931 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`". 932 * pidof uses space as delim, pgrep uses newline. :( 933 */ 934 int pid; 935 char *delim = opt + strcspn(opt, ", \n\t"); 936 char c = *delim; 937 938 *delim = '\0'; 939 pid = string_to_uint(opt); 940 if (pid <= 0) { 941 error_msg_and_die("Invalid process id: '%s'", opt); 942 } 943 if (pid == strace_tracer_pid) { 944 error_msg_and_die("I'm sorry, I can't let you do that, Dave."); 945 } 946 *delim = c; 947 alloctcb(pid); 948 if (c == '\0') 949 break; 950 opt = delim + 1; 951 } 952} 953 954static void 955startup_attach(void) 956{ 957 int tcbi; 958 struct tcb *tcp; 959 960 /* 961 * Block user interruptions as we would leave the traced 962 * process stopped (process state T) if we would terminate in 963 * between PTRACE_ATTACH and wait4() on SIGSTOP. 964 * We rely on cleanup() from this point on. 965 */ 966 if (interactive) 967 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 968 969 if (daemonized_tracer) { 970 pid_t pid = fork(); 971 if (pid < 0) { 972 perror_msg_and_die("fork"); 973 } 974 if (pid) { /* parent */ 975 /* 976 * Wait for grandchild to attach to straced process 977 * (grandparent). Grandchild SIGKILLs us after it attached. 978 * Grandparent's wait() is unblocked by our death, 979 * it proceeds to exec the straced program. 980 */ 981 pause(); 982 _exit(0); /* paranoia */ 983 } 984 /* grandchild */ 985 /* We will be the tracer process. Remember our new pid: */ 986 strace_tracer_pid = getpid(); 987 } 988 989 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) { 990 tcp = tcbtab[tcbi]; 991 992 if (!tcp->pid) 993 continue; 994 995 /* Is this a process we should attach to, but not yet attached? */ 996 if (tcp->flags & TCB_ATTACHED) 997 continue; /* no, we already attached it */ 998 999 if (followfork && !daemonized_tracer) { 1000 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3]; 1001 DIR *dir; 1002 1003 sprintf(procdir, "/proc/%d/task", tcp->pid); 1004 dir = opendir(procdir); 1005 if (dir != NULL) { 1006 unsigned int ntid = 0, nerr = 0; 1007 struct_dirent *de; 1008 1009 while ((de = read_dir(dir)) != NULL) { 1010 struct tcb *cur_tcp; 1011 int tid; 1012 1013 if (de->d_fileno == 0) 1014 continue; 1015 /* we trust /proc filesystem */ 1016 tid = atoi(de->d_name); 1017 if (tid <= 0) 1018 continue; 1019 ++ntid; 1020 if (ptrace_attach_or_seize(tid) < 0) { 1021 ++nerr; 1022 if (debug_flag) 1023 fprintf(stderr, "attach to pid %d failed\n", tid); 1024 continue; 1025 } 1026 if (debug_flag) 1027 fprintf(stderr, "attach to pid %d succeeded\n", tid); 1028 cur_tcp = tcp; 1029 if (tid != tcp->pid) 1030 cur_tcp = alloctcb(tid); 1031 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1032 newoutf(cur_tcp); 1033 } 1034 closedir(dir); 1035 if (interactive) { 1036 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1037 if (interrupted) 1038 goto ret; 1039 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1040 } 1041 ntid -= nerr; 1042 if (ntid == 0) { 1043 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1044 droptcb(tcp); 1045 continue; 1046 } 1047 if (!qflag) { 1048 fprintf(stderr, ntid > 1 1049? "Process %u attached with %u threads\n" 1050: "Process %u attached\n", 1051 tcp->pid, ntid); 1052 } 1053 if (!(tcp->flags & TCB_ATTACHED)) { 1054 /* -p PID, we failed to attach to PID itself 1055 * but did attach to some of its sibling threads. 1056 * Drop PID's tcp. 1057 */ 1058 droptcb(tcp); 1059 } 1060 continue; 1061 } /* if (opendir worked) */ 1062 } /* if (-f) */ 1063 if (ptrace_attach_or_seize(tcp->pid) < 0) { 1064 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1065 droptcb(tcp); 1066 continue; 1067 } 1068 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1069 newoutf(tcp); 1070 if (debug_flag) 1071 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid); 1072 1073 if (daemonized_tracer) { 1074 /* 1075 * Make parent go away. 1076 * Also makes grandparent's wait() unblock. 1077 */ 1078 kill(getppid(), SIGKILL); 1079 } 1080 1081 if (!qflag) 1082 fprintf(stderr, 1083 "Process %u attached\n", 1084 tcp->pid); 1085 } /* for each tcbtab[] */ 1086 1087 ret: 1088 if (interactive) 1089 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1090} 1091 1092/* Stack-o-phobic exec helper, in the hope to work around 1093 * NOMMU + "daemonized tracer" difficulty. 1094 */ 1095struct exec_params { 1096 int fd_to_close; 1097 uid_t run_euid; 1098 gid_t run_egid; 1099 char **argv; 1100 char *pathname; 1101}; 1102static struct exec_params params_for_tracee; 1103static void __attribute__ ((noinline, noreturn)) 1104exec_or_die(void) 1105{ 1106 struct exec_params *params = ¶ms_for_tracee; 1107 1108 if (params->fd_to_close >= 0) 1109 close(params->fd_to_close); 1110 if (!daemonized_tracer && !use_seize) { 1111 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) { 1112 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)"); 1113 } 1114 } 1115 1116 if (username != NULL) { 1117 /* 1118 * It is important to set groups before we 1119 * lose privileges on setuid. 1120 */ 1121 if (initgroups(username, run_gid) < 0) { 1122 perror_msg_and_die("initgroups"); 1123 } 1124 if (setregid(run_gid, params->run_egid) < 0) { 1125 perror_msg_and_die("setregid"); 1126 } 1127 if (setreuid(run_uid, params->run_euid) < 0) { 1128 perror_msg_and_die("setreuid"); 1129 } 1130 } 1131 else if (geteuid() != 0) 1132 if (setreuid(run_uid, run_uid) < 0) { 1133 perror_msg_and_die("setreuid"); 1134 } 1135 1136 if (!daemonized_tracer) { 1137 /* 1138 * Induce a ptrace stop. Tracer (our parent) 1139 * will resume us with PTRACE_SYSCALL and display 1140 * the immediately following execve syscall. 1141 * Can't do this on NOMMU systems, we are after 1142 * vfork: parent is blocked, stopping would deadlock. 1143 */ 1144 if (!NOMMU_SYSTEM) 1145 kill(getpid(), SIGSTOP); 1146 } else { 1147 alarm(3); 1148 /* we depend on SIGCHLD set to SIG_DFL by init code */ 1149 /* if it happens to be SIG_IGN'ed, wait won't block */ 1150 wait(NULL); 1151 alarm(0); 1152 } 1153 1154 execv(params->pathname, params->argv); 1155 perror_msg_and_die("exec"); 1156} 1157 1158static void 1159startup_child(char **argv) 1160{ 1161 struct_stat statbuf; 1162 const char *filename; 1163 char pathname[MAXPATHLEN]; 1164 int pid; 1165 struct tcb *tcp; 1166 1167 filename = argv[0]; 1168 if (strchr(filename, '/')) { 1169 if (strlen(filename) > sizeof pathname - 1) { 1170 errno = ENAMETOOLONG; 1171 perror_msg_and_die("exec"); 1172 } 1173 strcpy(pathname, filename); 1174 } 1175#ifdef USE_DEBUGGING_EXEC 1176 /* 1177 * Debuggers customarily check the current directory 1178 * first regardless of the path but doing that gives 1179 * security geeks a panic attack. 1180 */ 1181 else if (stat_file(filename, &statbuf) == 0) 1182 strcpy(pathname, filename); 1183#endif /* USE_DEBUGGING_EXEC */ 1184 else { 1185 const char *path; 1186 int m, n, len; 1187 1188 for (path = getenv("PATH"); path && *path; path += m) { 1189 const char *colon = strchr(path, ':'); 1190 if (colon) { 1191 n = colon - path; 1192 m = n + 1; 1193 } 1194 else 1195 m = n = strlen(path); 1196 if (n == 0) { 1197 if (!getcwd(pathname, MAXPATHLEN)) 1198 continue; 1199 len = strlen(pathname); 1200 } 1201 else if (n > sizeof pathname - 1) 1202 continue; 1203 else { 1204 strncpy(pathname, path, n); 1205 len = n; 1206 } 1207 if (len && pathname[len - 1] != '/') 1208 pathname[len++] = '/'; 1209 strcpy(pathname + len, filename); 1210 if (stat_file(pathname, &statbuf) == 0 && 1211 /* Accept only regular files 1212 with some execute bits set. 1213 XXX not perfect, might still fail */ 1214 S_ISREG(statbuf.st_mode) && 1215 (statbuf.st_mode & 0111)) 1216 break; 1217 } 1218 } 1219 if (stat_file(pathname, &statbuf) < 0) { 1220 perror_msg_and_die("Can't stat '%s'", filename); 1221 } 1222 1223 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1; 1224 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid; 1225 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid; 1226 params_for_tracee.argv = argv; 1227 /* 1228 * On NOMMU, can be safely freed only after execve in tracee. 1229 * It's hard to know when that happens, so we just leak it. 1230 */ 1231 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname; 1232 1233#if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY 1234 if (daemonized_tracer) 1235 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY); 1236#endif 1237 1238 pid = fork(); 1239 if (pid < 0) { 1240 perror_msg_and_die("fork"); 1241 } 1242 if ((pid != 0 && daemonized_tracer) 1243 || (pid == 0 && !daemonized_tracer) 1244 ) { 1245 /* We are to become the tracee. Two cases: 1246 * -D: we are parent 1247 * not -D: we are child 1248 */ 1249 exec_or_die(); 1250 } 1251 1252 /* We are the tracer */ 1253 1254 if (!daemonized_tracer) { 1255 strace_child = pid; 1256 if (!use_seize) { 1257 /* child did PTRACE_TRACEME, nothing to do in parent */ 1258 } else { 1259 if (!NOMMU_SYSTEM) { 1260 /* Wait until child stopped itself */ 1261 int status; 1262 while (waitpid(pid, &status, WSTOPPED) < 0) { 1263 if (errno == EINTR) 1264 continue; 1265 perror_msg_and_die("waitpid"); 1266 } 1267 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) { 1268 kill_save_errno(pid, SIGKILL); 1269 perror_msg_and_die("Unexpected wait status %x", status); 1270 } 1271 } 1272 /* Else: NOMMU case, we have no way to sync. 1273 * Just attach to it as soon as possible. 1274 * This means that we may miss a few first syscalls... 1275 */ 1276 1277 if (ptrace_attach_or_seize(pid)) { 1278 kill_save_errno(pid, SIGKILL); 1279 perror_msg_and_die("Can't attach to %d", pid); 1280 } 1281 if (!NOMMU_SYSTEM) 1282 kill(pid, SIGCONT); 1283 } 1284 tcp = alloctcb(pid); 1285 if (!NOMMU_SYSTEM) 1286 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1287 else 1288 tcp->flags |= TCB_ATTACHED | TCB_STARTUP; 1289 newoutf(tcp); 1290 } 1291 else { 1292 /* With -D, we are *child* here, IOW: different pid. Fetch it: */ 1293 strace_tracer_pid = getpid(); 1294 /* The tracee is our parent: */ 1295 pid = getppid(); 1296 alloctcb(pid); 1297 /* attaching will be done later, by startup_attach */ 1298 /* note: we don't do newoutf(tcp) here either! */ 1299 1300 /* NOMMU BUG! -D mode is active, we (child) return, 1301 * and we will scribble over parent's stack! 1302 * When parent later unpauses, it segfaults. 1303 * 1304 * We work around it 1305 * (1) by declaring exec_or_die() NORETURN, 1306 * hopefully compiler will just jump to it 1307 * instead of call (won't push anything to stack), 1308 * (2) by trying very hard in exec_or_die() 1309 * to not use any stack, 1310 * (3) having a really big (MAXPATHLEN) stack object 1311 * in this function, which creates a "buffer" between 1312 * child's and parent's stack pointers. 1313 * This may save us if (1) and (2) failed 1314 * and compiler decided to use stack in exec_or_die() anyway 1315 * (happens on i386 because of stack parameter passing). 1316 * 1317 * A cleaner solution is to use makecontext + setcontext 1318 * to create a genuine separate stack and execute on it. 1319 */ 1320 } 1321} 1322 1323/* 1324 * Test whether the kernel support PTRACE_O_TRACECLONE et al options. 1325 * First fork a new child, call ptrace with PTRACE_SETOPTIONS on it, 1326 * and then see which options are supported by the kernel. 1327 */ 1328static int 1329test_ptrace_setoptions_followfork(void) 1330{ 1331 int pid, expected_grandchild = 0, found_grandchild = 0; 1332 const unsigned int test_options = PTRACE_O_TRACECLONE | 1333 PTRACE_O_TRACEFORK | 1334 PTRACE_O_TRACEVFORK; 1335 1336 /* Need fork for test. NOMMU has no forks */ 1337 if (NOMMU_SYSTEM) 1338 goto worked; /* be bold, and pretend that test succeeded */ 1339 1340 pid = fork(); 1341 if (pid < 0) 1342 perror_msg_and_die("fork"); 1343 if (pid == 0) { 1344 pid = getpid(); 1345 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1346 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1347 __func__); 1348 kill_save_errno(pid, SIGSTOP); 1349 if (fork() < 0) 1350 perror_msg_and_die("fork"); 1351 _exit(0); 1352 } 1353 1354 while (1) { 1355 int status, tracee_pid; 1356 1357 errno = 0; 1358 tracee_pid = wait(&status); 1359 if (tracee_pid <= 0) { 1360 if (errno == EINTR) 1361 continue; 1362 if (errno == ECHILD) 1363 break; 1364 kill_save_errno(pid, SIGKILL); 1365 perror_msg_and_die("%s: unexpected wait result %d", 1366 __func__, tracee_pid); 1367 } 1368 if (WIFEXITED(status)) { 1369 if (WEXITSTATUS(status)) { 1370 if (tracee_pid != pid) 1371 kill_save_errno(pid, SIGKILL); 1372 error_msg_and_die("%s: unexpected exit status %u", 1373 __func__, WEXITSTATUS(status)); 1374 } 1375 continue; 1376 } 1377 if (WIFSIGNALED(status)) { 1378 if (tracee_pid != pid) 1379 kill_save_errno(pid, SIGKILL); 1380 error_msg_and_die("%s: unexpected signal %u", 1381 __func__, WTERMSIG(status)); 1382 } 1383 if (!WIFSTOPPED(status)) { 1384 if (tracee_pid != pid) 1385 kill_save_errno(tracee_pid, SIGKILL); 1386 kill_save_errno(pid, SIGKILL); 1387 error_msg_and_die("%s: unexpected wait status %x", 1388 __func__, status); 1389 } 1390 if (tracee_pid != pid) { 1391 found_grandchild = tracee_pid; 1392 if (ptrace(PTRACE_CONT, tracee_pid, 0, 0) < 0) { 1393 kill_save_errno(tracee_pid, SIGKILL); 1394 kill_save_errno(pid, SIGKILL); 1395 perror_msg_and_die("PTRACE_CONT doesn't work"); 1396 } 1397 continue; 1398 } 1399 switch (WSTOPSIG(status)) { 1400 case SIGSTOP: 1401 if (ptrace(PTRACE_SETOPTIONS, pid, 0, test_options) < 0 1402 && errno != EINVAL && errno != EIO) 1403 perror_msg("PTRACE_SETOPTIONS"); 1404 break; 1405 case SIGTRAP: 1406 if (status >> 16 == PTRACE_EVENT_FORK) { 1407 long msg = 0; 1408 1409 if (ptrace(PTRACE_GETEVENTMSG, pid, 1410 NULL, (long) &msg) == 0) 1411 expected_grandchild = msg; 1412 } 1413 break; 1414 } 1415 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) { 1416 kill_save_errno(pid, SIGKILL); 1417 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1418 } 1419 } 1420 if (expected_grandchild && expected_grandchild == found_grandchild) { 1421 worked: 1422 ptrace_setoptions |= test_options; 1423 if (debug_flag) 1424 fprintf(stderr, "ptrace_setoptions = %#x\n", 1425 ptrace_setoptions); 1426 return 0; 1427 } 1428 error_msg("Test for PTRACE_O_TRACECLONE failed, " 1429 "giving up using this feature."); 1430 return 1; 1431} 1432 1433/* 1434 * Test whether the kernel support PTRACE_O_TRACESYSGOOD. 1435 * First fork a new child, call ptrace(PTRACE_SETOPTIONS) on it, 1436 * and then see whether it will stop with (SIGTRAP | 0x80). 1437 * 1438 * Use of this option enables correct handling of user-generated SIGTRAPs, 1439 * and SIGTRAPs generated by special instructions such as int3 on x86: 1440 1441# compile with: gcc -nostartfiles -nostdlib -o int3 int3.S 1442_start: .globl _start 1443 int3 1444 movl $42, %ebx 1445 movl $1, %eax 1446 int $0x80 1447 */ 1448static int 1449test_ptrace_setoptions_for_all(void) 1450{ 1451 const unsigned int test_options = PTRACE_O_TRACESYSGOOD | 1452 PTRACE_O_TRACEEXEC; 1453 int pid; 1454 int it_worked = 0; 1455 1456 /* Need fork for test. NOMMU has no forks */ 1457 if (NOMMU_SYSTEM) 1458 goto worked; /* be bold, and pretend that test succeeded */ 1459 1460 pid = fork(); 1461 if (pid < 0) 1462 perror_msg_and_die("fork"); 1463 1464 if (pid == 0) { 1465 pid = getpid(); 1466 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) 1467 /* Note: exits with exitcode 1 */ 1468 perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", 1469 __func__); 1470 kill(pid, SIGSTOP); 1471 _exit(0); /* parent should see entry into this syscall */ 1472 } 1473 1474 while (1) { 1475 int status, tracee_pid; 1476 1477 errno = 0; 1478 tracee_pid = wait(&status); 1479 if (tracee_pid <= 0) { 1480 if (errno == EINTR) 1481 continue; 1482 kill_save_errno(pid, SIGKILL); 1483 perror_msg_and_die("%s: unexpected wait result %d", 1484 __func__, tracee_pid); 1485 } 1486 if (WIFEXITED(status)) { 1487 if (WEXITSTATUS(status) == 0) 1488 break; 1489 error_msg_and_die("%s: unexpected exit status %u", 1490 __func__, WEXITSTATUS(status)); 1491 } 1492 if (WIFSIGNALED(status)) { 1493 error_msg_and_die("%s: unexpected signal %u", 1494 __func__, WTERMSIG(status)); 1495 } 1496 if (!WIFSTOPPED(status)) { 1497 kill(pid, SIGKILL); 1498 error_msg_and_die("%s: unexpected wait status %x", 1499 __func__, status); 1500 } 1501 if (WSTOPSIG(status) == SIGSTOP) { 1502 /* 1503 * We don't check "options aren't accepted" error. 1504 * If it happens, we'll never get (SIGTRAP | 0x80), 1505 * and thus will decide to not use the option. 1506 * IOW: the outcome of the test will be correct. 1507 */ 1508 if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0 1509 && errno != EINVAL && errno != EIO) 1510 perror_msg("PTRACE_SETOPTIONS"); 1511 } 1512 if (WSTOPSIG(status) == (SIGTRAP | 0x80)) { 1513 it_worked = 1; 1514 } 1515 if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) { 1516 kill_save_errno(pid, SIGKILL); 1517 perror_msg_and_die("PTRACE_SYSCALL doesn't work"); 1518 } 1519 } 1520 1521 if (it_worked) { 1522 worked: 1523 syscall_trap_sig = (SIGTRAP | 0x80); 1524 ptrace_setoptions |= test_options; 1525 if (debug_flag) 1526 fprintf(stderr, "ptrace_setoptions = %#x\n", 1527 ptrace_setoptions); 1528 return 0; 1529 } 1530 1531 error_msg("Test for PTRACE_O_TRACESYSGOOD failed, " 1532 "giving up using this feature."); 1533 return 1; 1534} 1535 1536#if USE_SEIZE 1537static void 1538test_ptrace_seize(void) 1539{ 1540 int pid; 1541 1542 /* Need fork for test. NOMMU has no forks */ 1543 if (NOMMU_SYSTEM) { 1544 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1545 return; 1546 } 1547 1548 pid = fork(); 1549 if (pid < 0) 1550 perror_msg_and_die("fork"); 1551 1552 if (pid == 0) { 1553 pause(); 1554 _exit(0); 1555 } 1556 1557 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After 1558 * attaching tracee continues to run unless a trap condition occurs. 1559 * PTRACE_SEIZE doesn't affect signal or group stop state. 1560 */ 1561 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) { 1562 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1563 } else if (debug_flag) { 1564 fprintf(stderr, "PTRACE_SEIZE doesn't work\n"); 1565 } 1566 1567 kill(pid, SIGKILL); 1568 1569 while (1) { 1570 int status, tracee_pid; 1571 1572 errno = 0; 1573 tracee_pid = waitpid(pid, &status, 0); 1574 if (tracee_pid <= 0) { 1575 if (errno == EINTR) 1576 continue; 1577 perror_msg_and_die("%s: unexpected wait result %d", 1578 __func__, tracee_pid); 1579 } 1580 if (WIFSIGNALED(status)) { 1581 return; 1582 } 1583 error_msg_and_die("%s: unexpected wait status %x", 1584 __func__, status); 1585 } 1586} 1587#else /* !USE_SEIZE */ 1588# define test_ptrace_seize() ((void)0) 1589#endif 1590 1591static unsigned 1592get_os_release(void) 1593{ 1594 unsigned rel; 1595 const char *p; 1596 struct utsname u; 1597 if (uname(&u) < 0) 1598 perror_msg_and_die("uname"); 1599 /* u.release has this form: "3.2.9[-some-garbage]" */ 1600 rel = 0; 1601 p = u.release; 1602 for (;;) { 1603 if (!(*p >= '0' && *p <= '9')) 1604 error_msg_and_die("Bad OS release string: '%s'", u.release); 1605 /* Note: this open-codes KERNEL_VERSION(): */ 1606 rel = (rel << 8) | atoi(p); 1607 if (rel >= KERNEL_VERSION(1,0,0)) 1608 break; 1609 while (*p >= '0' && *p <= '9') 1610 p++; 1611 if (*p != '.') { 1612 if (rel >= KERNEL_VERSION(0,1,0)) { 1613 /* "X.Y-something" means "X.Y.0" */ 1614 rel <<= 8; 1615 break; 1616 } 1617 error_msg_and_die("Bad OS release string: '%s'", u.release); 1618 } 1619 p++; 1620 } 1621 return rel; 1622} 1623 1624/* 1625 * Initialization part of main() was eating much stack (~0.5k), 1626 * which was unused after init. 1627 * We can reuse it if we move init code into a separate function. 1628 * 1629 * Don't want main() to inline us and defeat the reason 1630 * we have a separate function. 1631 */ 1632static void __attribute__ ((noinline)) 1633init(int argc, char *argv[]) 1634{ 1635 struct tcb *tcp; 1636 int c, i; 1637 int optF = 0; 1638 struct sigaction sa; 1639 1640 progname = argv[0] ? argv[0] : "strace"; 1641 1642 /* Make sure SIGCHLD has the default action so that waitpid 1643 definitely works without losing track of children. The user 1644 should not have given us a bogus state to inherit, but he might 1645 have. Arguably we should detect SIG_IGN here and pass it on 1646 to children, but probably noone really needs that. */ 1647 signal(SIGCHLD, SIG_DFL); 1648 1649 strace_tracer_pid = getpid(); 1650 1651 os_release = get_os_release(); 1652 1653 /* Allocate the initial tcbtab. */ 1654 tcbtabsize = argc; /* Surely enough for all -p args. */ 1655 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0])); 1656 if (!tcbtab) 1657 die_out_of_memory(); 1658 tcp = calloc(tcbtabsize, sizeof(*tcp)); 1659 if (!tcp) 1660 die_out_of_memory(); 1661 for (c = 0; c < tcbtabsize; c++) 1662 tcbtab[c] = tcp++; 1663 1664 shared_log = stderr; 1665 set_sortby(DEFAULT_SORTBY); 1666 set_personality(DEFAULT_PERSONALITY); 1667 qualify("trace=all"); 1668 qualify("abbrev=all"); 1669 qualify("verbose=all"); 1670#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE) 1671# error Bug in DEFAULT_QUAL_FLAGS 1672#endif 1673 qualify("signal=all"); 1674 while ((c = getopt(argc, argv, 1675 "+b:cCdfFhiqrtTvVwxyz" 1676#ifdef USE_LIBUNWIND 1677 "k" 1678#endif 1679 "D" 1680 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) { 1681 switch (c) { 1682 case 'b': 1683 if (strcmp(optarg, "execve") != 0) 1684 error_msg_and_die("Syscall '%s' for -b isn't supported", 1685 optarg); 1686 detach_on_execve = 1; 1687 break; 1688 case 'c': 1689 if (cflag == CFLAG_BOTH) { 1690 error_msg_and_die("-c and -C are mutually exclusive"); 1691 } 1692 cflag = CFLAG_ONLY_STATS; 1693 break; 1694 case 'C': 1695 if (cflag == CFLAG_ONLY_STATS) { 1696 error_msg_and_die("-c and -C are mutually exclusive"); 1697 } 1698 cflag = CFLAG_BOTH; 1699 break; 1700 case 'd': 1701 debug_flag = 1; 1702 break; 1703 case 'D': 1704 daemonized_tracer = 1; 1705 break; 1706 case 'F': 1707 optF = 1; 1708 break; 1709 case 'f': 1710 followfork++; 1711 break; 1712 case 'h': 1713 usage(stdout, 0); 1714 break; 1715 case 'i': 1716 iflag = 1; 1717 break; 1718 case 'q': 1719 qflag++; 1720 break; 1721 case 'r': 1722 rflag = 1; 1723 /* fall through to tflag++ */ 1724 case 't': 1725 tflag++; 1726 break; 1727 case 'T': 1728 Tflag = 1; 1729 break; 1730 case 'w': 1731 count_wallclock = 1; 1732 break; 1733 case 'x': 1734 xflag++; 1735 break; 1736 case 'y': 1737 show_fd_path = 1; 1738 break; 1739 case 'v': 1740 qualify("abbrev=none"); 1741 break; 1742 case 'V': 1743 printf("%s -- version %s\n", PACKAGE_NAME, VERSION); 1744 exit(0); 1745 break; 1746 case 'z': 1747 not_failing_only = 1; 1748 break; 1749 case 'a': 1750 acolumn = string_to_uint(optarg); 1751 if (acolumn < 0) 1752 error_opt_arg(c, optarg); 1753 break; 1754 case 'e': 1755 qualify(optarg); 1756 break; 1757 case 'o': 1758 outfname = strdup(optarg); 1759 break; 1760 case 'O': 1761 i = string_to_uint(optarg); 1762 if (i < 0) 1763 error_opt_arg(c, optarg); 1764 set_overhead(i); 1765 break; 1766 case 'p': 1767 process_opt_p_list(optarg); 1768 break; 1769 case 'P': 1770 pathtrace_select(optarg); 1771 break; 1772 case 's': 1773 i = string_to_uint(optarg); 1774 if (i < 0) 1775 error_opt_arg(c, optarg); 1776 max_strlen = i; 1777 break; 1778 case 'S': 1779 set_sortby(optarg); 1780 break; 1781 case 'u': 1782 username = strdup(optarg); 1783 break; 1784#ifdef USE_LIBUNWIND 1785 case 'k': 1786 stack_trace_enabled = true; 1787 break; 1788#endif 1789 case 'E': 1790 if (putenv(optarg) < 0) 1791 die_out_of_memory(); 1792 break; 1793 case 'I': 1794 opt_intr = string_to_uint(optarg); 1795 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS) 1796 error_opt_arg(c, optarg); 1797 break; 1798 default: 1799 usage(stderr, 1); 1800 break; 1801 } 1802 } 1803 argv += optind; 1804 /* argc -= optind; - no need, argc is not used below */ 1805 1806 acolumn_spaces = malloc(acolumn + 1); 1807 if (!acolumn_spaces) 1808 die_out_of_memory(); 1809 memset(acolumn_spaces, ' ', acolumn); 1810 acolumn_spaces[acolumn] = '\0'; 1811 1812 /* Must have PROG [ARGS], or -p PID. Not both. */ 1813 if (!argv[0] == !nprocs) 1814 usage(stderr, 1); 1815 1816 if (nprocs != 0 && daemonized_tracer) { 1817 error_msg_and_die("-D and -p are mutually exclusive"); 1818 } 1819 1820 if (!followfork) 1821 followfork = optF; 1822 1823 if (followfork >= 2 && cflag) { 1824 error_msg_and_die("(-c or -C) and -ff are mutually exclusive"); 1825 } 1826 1827 if (count_wallclock && !cflag) { 1828 error_msg_and_die("-w must be given with (-c or -C)"); 1829 } 1830 1831 if (cflag == CFLAG_ONLY_STATS) { 1832 if (iflag) 1833 error_msg("-%c has no effect with -c", 'i'); 1834#ifdef USE_LIBUNWIND 1835 if (stack_trace_enabled) 1836 error_msg("-%c has no effect with -c", 'k'); 1837#endif 1838 if (rflag) 1839 error_msg("-%c has no effect with -c", 'r'); 1840 if (tflag) 1841 error_msg("-%c has no effect with -c", 't'); 1842 if (Tflag) 1843 error_msg("-%c has no effect with -c", 'T'); 1844 if (show_fd_path) 1845 error_msg("-%c has no effect with -c", 'y'); 1846 } 1847 1848#ifdef USE_LIBUNWIND 1849 if (stack_trace_enabled) 1850 unwind_init(); 1851#endif 1852 1853 /* See if they want to run as another user. */ 1854 if (username != NULL) { 1855 struct passwd *pent; 1856 1857 if (getuid() != 0 || geteuid() != 0) { 1858 error_msg_and_die("You must be root to use the -u option"); 1859 } 1860 pent = getpwnam(username); 1861 if (pent == NULL) { 1862 error_msg_and_die("Cannot find user '%s'", username); 1863 } 1864 run_uid = pent->pw_uid; 1865 run_gid = pent->pw_gid; 1866 } 1867 else { 1868 run_uid = getuid(); 1869 run_gid = getgid(); 1870 } 1871 1872 /* 1873 * On any reasonably recent Linux kernel (circa about 2.5.46) 1874 * need_fork_exec_workarounds should stay 0 after these tests: 1875 */ 1876 /*need_fork_exec_workarounds = 0; - already is */ 1877 if (followfork) 1878 need_fork_exec_workarounds = test_ptrace_setoptions_followfork(); 1879 need_fork_exec_workarounds |= test_ptrace_setoptions_for_all(); 1880 test_ptrace_seize(); 1881 1882 /* Check if they want to redirect the output. */ 1883 if (outfname) { 1884 /* See if they want to pipe the output. */ 1885 if (outfname[0] == '|' || outfname[0] == '!') { 1886 /* 1887 * We can't do the <outfname>.PID funny business 1888 * when using popen, so prohibit it. 1889 */ 1890 if (followfork >= 2) 1891 error_msg_and_die("Piping the output and -ff are mutually exclusive"); 1892 shared_log = strace_popen(outfname + 1); 1893 } 1894 else if (followfork < 2) 1895 shared_log = strace_fopen(outfname); 1896 } else { 1897 /* -ff without -o FILE is the same as single -f */ 1898 if (followfork >= 2) 1899 followfork = 1; 1900 } 1901 1902 if (!outfname || outfname[0] == '|' || outfname[0] == '!') { 1903 char *buf = malloc(BUFSIZ); 1904 if (!buf) 1905 die_out_of_memory(); 1906 setvbuf(shared_log, buf, _IOLBF, BUFSIZ); 1907 } 1908 if (outfname && argv[0]) { 1909 if (!opt_intr) 1910 opt_intr = INTR_NEVER; 1911 qflag = 1; 1912 } 1913 if (!opt_intr) 1914 opt_intr = INTR_WHILE_WAIT; 1915 1916 /* argv[0] -pPID -oFILE Default interactive setting 1917 * yes 0 0 INTR_WHILE_WAIT 1918 * no 1 0 INTR_WHILE_WAIT 1919 * yes 0 1 INTR_NEVER 1920 * no 1 1 INTR_WHILE_WAIT 1921 */ 1922 1923 sigemptyset(&empty_set); 1924 sigemptyset(&blocked_set); 1925 1926 /* startup_child() must be called before the signal handlers get 1927 * installed below as they are inherited into the spawned process. 1928 * Also we do not need to be protected by them as during interruption 1929 * in the startup_child() mode we kill the spawned process anyway. 1930 */ 1931 if (argv[0]) { 1932 if (!NOMMU_SYSTEM || daemonized_tracer) 1933 hide_log_until_execve = 1; 1934 skip_one_b_execve = 1; 1935 startup_child(argv); 1936 } 1937 1938 sa.sa_handler = SIG_IGN; 1939 sigemptyset(&sa.sa_mask); 1940 sa.sa_flags = 0; 1941 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */ 1942 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */ 1943 if (opt_intr != INTR_ANYWHERE) { 1944 if (opt_intr == INTR_BLOCK_TSTP_TOO) 1945 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */ 1946 /* 1947 * In interactive mode (if no -o OUTFILE, or -p PID is used), 1948 * fatal signals are blocked while syscall stop is processed, 1949 * and acted on in between, when waiting for new syscall stops. 1950 * In non-interactive mode, signals are ignored. 1951 */ 1952 if (opt_intr == INTR_WHILE_WAIT) { 1953 sigaddset(&blocked_set, SIGHUP); 1954 sigaddset(&blocked_set, SIGINT); 1955 sigaddset(&blocked_set, SIGQUIT); 1956 sigaddset(&blocked_set, SIGPIPE); 1957 sigaddset(&blocked_set, SIGTERM); 1958 sa.sa_handler = interrupt; 1959 } 1960 /* SIG_IGN, or set handler for these */ 1961 sigaction(SIGHUP, &sa, NULL); 1962 sigaction(SIGINT, &sa, NULL); 1963 sigaction(SIGQUIT, &sa, NULL); 1964 sigaction(SIGPIPE, &sa, NULL); 1965 sigaction(SIGTERM, &sa, NULL); 1966 } 1967 if (nprocs != 0 || daemonized_tracer) 1968 startup_attach(); 1969 1970 /* Do we want pids printed in our -o OUTFILE? 1971 * -ff: no (every pid has its own file); or 1972 * -f: yes (there can be more pids in the future); or 1973 * -p PID1,PID2: yes (there are already more than one pid) 1974 */ 1975 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1)); 1976} 1977 1978static struct tcb * 1979pid2tcb(int pid) 1980{ 1981 int i; 1982 1983 if (pid <= 0) 1984 return NULL; 1985 1986 for (i = 0; i < tcbtabsize; i++) { 1987 struct tcb *tcp = tcbtab[i]; 1988 if (tcp->pid == pid) 1989 return tcp; 1990 } 1991 1992 return NULL; 1993} 1994 1995static void 1996cleanup(void) 1997{ 1998 int i; 1999 struct tcb *tcp; 2000 int fatal_sig; 2001 2002 /* 'interrupted' is a volatile object, fetch it only once */ 2003 fatal_sig = interrupted; 2004 if (!fatal_sig) 2005 fatal_sig = SIGTERM; 2006 2007 for (i = 0; i < tcbtabsize; i++) { 2008 tcp = tcbtab[i]; 2009 if (!tcp->pid) 2010 continue; 2011 if (debug_flag) 2012 fprintf(stderr, 2013 "cleanup: looking at pid %u\n", tcp->pid); 2014 if (tcp->pid == strace_child) { 2015 kill(tcp->pid, SIGCONT); 2016 kill(tcp->pid, fatal_sig); 2017 } 2018 detach(tcp); 2019 } 2020 if (cflag) 2021 call_summary(shared_log); 2022} 2023 2024static void 2025interrupt(int sig) 2026{ 2027 interrupted = sig; 2028} 2029 2030static void 2031trace(void) 2032{ 2033 struct rusage ru; 2034 2035 /* Used to be "while (nprocs != 0)", but in this testcase: 2036 * int main() { _exit(!!fork()); } 2037 * under strace -f, parent sometimes (rarely) manages 2038 * to exit before we see the first stop of the child, 2039 * and we are losing track of it: 2040 * 19923 clone(...) = 19924 2041 * 19923 exit_group(1) = ? 2042 * 19923 +++ exited with 1 +++ 2043 * Waiting for ECHILD works better. 2044 * (However, if -o|logger is in use, we can't do that. 2045 * Can work around that by double-forking the logger, 2046 * but that loses the ability to wait for its completion on exit. 2047 * Oh well...) 2048 */ 2049 while (1) { 2050 int pid; 2051 int wait_errno; 2052 int status, sig; 2053 int stopped; 2054 struct tcb *tcp; 2055 unsigned event; 2056 2057 if (interrupted) 2058 return; 2059 2060 if (popen_pid != 0 && nprocs == 0) 2061 return; 2062 2063 if (interactive) 2064 sigprocmask(SIG_SETMASK, &empty_set, NULL); 2065 pid = wait4(-1, &status, __WALL, (cflag ? &ru : NULL)); 2066 wait_errno = errno; 2067 if (interactive) 2068 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 2069 2070 if (pid < 0) { 2071 if (wait_errno == EINTR) 2072 continue; 2073 if (nprocs == 0 && wait_errno == ECHILD) 2074 return; 2075 /* If nprocs > 0, ECHILD is not expected, 2076 * treat it as any other error here: 2077 */ 2078 errno = wait_errno; 2079 perror_msg_and_die("wait4(__WALL)"); 2080 } 2081 2082 if (pid == popen_pid) { 2083 if (!WIFSTOPPED(status)) 2084 popen_pid = 0; 2085 continue; 2086 } 2087 2088 event = ((unsigned)status >> 16); 2089 if (debug_flag) { 2090 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16]; 2091 char evbuf[sizeof(",EVENT_VFORK_DONE (%u)") + sizeof(int)*3 /*paranoia:*/ + 16]; 2092 strcpy(buf, "???"); 2093 if (WIFSIGNALED(status)) 2094#ifdef WCOREDUMP 2095 sprintf(buf, "WIFSIGNALED,%ssig=%s", 2096 WCOREDUMP(status) ? "core," : "", 2097 signame(WTERMSIG(status))); 2098#else 2099 sprintf(buf, "WIFSIGNALED,sig=%s", 2100 signame(WTERMSIG(status))); 2101#endif 2102 if (WIFEXITED(status)) 2103 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status)); 2104 if (WIFSTOPPED(status)) 2105 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status))); 2106#ifdef WIFCONTINUED 2107 /* Should never be seen */ 2108 if (WIFCONTINUED(status)) 2109 strcpy(buf, "WIFCONTINUED"); 2110#endif 2111 evbuf[0] = '\0'; 2112 if (event != 0) { 2113 static const char *const event_names[] = { 2114 [PTRACE_EVENT_CLONE] = "CLONE", 2115 [PTRACE_EVENT_FORK] = "FORK", 2116 [PTRACE_EVENT_VFORK] = "VFORK", 2117 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE", 2118 [PTRACE_EVENT_EXEC] = "EXEC", 2119 [PTRACE_EVENT_EXIT] = "EXIT", 2120 /* [PTRACE_EVENT_STOP (=128)] would make biggish array */ 2121 }; 2122 const char *e = "??"; 2123 if (event < ARRAY_SIZE(event_names)) 2124 e = event_names[event]; 2125 else if (event == PTRACE_EVENT_STOP) 2126 e = "STOP"; 2127 sprintf(evbuf, ",EVENT_%s (%u)", e, event); 2128 } 2129 fprintf(stderr, " [wait(0x%06x) = %u] %s%s\n", status, pid, buf, evbuf); 2130 } 2131 2132 /* Look up 'pid' in our table. */ 2133 tcp = pid2tcb(pid); 2134 2135 if (!tcp) { 2136 if (!WIFSTOPPED(status)) { 2137 /* This can happen if we inherited 2138 * an unknown child. Example: 2139 * (sleep 1 & exec strace sleep 2) 2140 */ 2141 error_msg("Exit of unknown pid %u seen", pid); 2142 continue; 2143 } 2144 if (followfork) { 2145 /* We assume it's a fork/vfork/clone child */ 2146 tcp = alloctcb(pid); 2147 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 2148 newoutf(tcp); 2149 if (!qflag) 2150 fprintf(stderr, "Process %d attached\n", 2151 pid); 2152 } else { 2153 /* This can happen if a clone call used 2154 * CLONE_PTRACE itself. 2155 */ 2156 ptrace(PTRACE_CONT, pid, (char *) 0, 0); 2157 error_msg("Stop of unknown pid %u seen, PTRACE_CONTed it", pid); 2158 continue; 2159 } 2160 } 2161 2162 clear_regs(); 2163 if (WIFSTOPPED(status)) 2164 get_regs(pid); 2165 2166 /* Under Linux, execve changes pid to thread leader's pid, 2167 * and we see this changed pid on EVENT_EXEC and later, 2168 * execve sysexit. Leader "disappears" without exit 2169 * notification. Let user know that, drop leader's tcb, 2170 * and fix up pid in execve thread's tcb. 2171 * Effectively, execve thread's tcb replaces leader's tcb. 2172 * 2173 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED 2174 * on exit syscall) in multithreaded programs exactly 2175 * in order to handle this case. 2176 * 2177 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0. 2178 * On 2.6 and earlier, it can return garbage. 2179 */ 2180 if (event == PTRACE_EVENT_EXEC && os_release >= KERNEL_VERSION(3,0,0)) { 2181 FILE *fp; 2182 struct tcb *execve_thread; 2183 long old_pid = 0; 2184 2185 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0) 2186 goto dont_switch_tcbs; 2187 /* Avoid truncation in pid2tcb() param passing */ 2188 if (old_pid > UINT_MAX) 2189 goto dont_switch_tcbs; 2190 if (old_pid <= 0 || old_pid == pid) 2191 goto dont_switch_tcbs; 2192 execve_thread = pid2tcb(old_pid); 2193 /* It should be !NULL, but I feel paranoid */ 2194 if (!execve_thread) 2195 goto dont_switch_tcbs; 2196 2197 if (execve_thread->curcol != 0) { 2198 /* 2199 * One case we are here is -ff: 2200 * try "strace -oLOG -ff test/threaded_execve" 2201 */ 2202 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid); 2203 /*execve_thread->curcol = 0; - no need, see code below */ 2204 } 2205 /* Swap output FILEs (needed for -ff) */ 2206 fp = execve_thread->outf; 2207 execve_thread->outf = tcp->outf; 2208 tcp->outf = fp; 2209 /* And their column positions */ 2210 execve_thread->curcol = tcp->curcol; 2211 tcp->curcol = 0; 2212 /* Drop leader, but close execve'd thread outfile (if -ff) */ 2213 droptcb(tcp); 2214 /* Switch to the thread, reusing leader's outfile and pid */ 2215 tcp = execve_thread; 2216 tcp->pid = pid; 2217 if (cflag != CFLAG_ONLY_STATS) { 2218 printleader(tcp); 2219 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid); 2220 line_ended(); 2221 tcp->flags |= TCB_REPRINT; 2222 } 2223 } 2224 dont_switch_tcbs: 2225 2226 if (event == PTRACE_EVENT_EXEC) { 2227 if (detach_on_execve && !skip_one_b_execve) 2228 detach(tcp); /* do "-b execve" thingy */ 2229 skip_one_b_execve = 0; 2230 } 2231 2232 /* Set current output file */ 2233 current_tcp = tcp; 2234 2235 if (cflag) { 2236 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime); 2237 tcp->stime = ru.ru_stime; 2238 } 2239 2240 if (WIFSIGNALED(status)) { 2241 if (pid == strace_child) 2242 exit_code = 0x100 | WTERMSIG(status); 2243 if (cflag != CFLAG_ONLY_STATS 2244 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL) 2245 ) { 2246 printleader(tcp); 2247#ifdef WCOREDUMP 2248 tprintf("+++ killed by %s %s+++\n", 2249 signame(WTERMSIG(status)), 2250 WCOREDUMP(status) ? "(core dumped) " : ""); 2251#else 2252 tprintf("+++ killed by %s +++\n", 2253 signame(WTERMSIG(status))); 2254#endif 2255 line_ended(); 2256 } 2257 droptcb(tcp); 2258 continue; 2259 } 2260 if (WIFEXITED(status)) { 2261 if (pid == strace_child) 2262 exit_code = WEXITSTATUS(status); 2263 if (cflag != CFLAG_ONLY_STATS && 2264 qflag < 2) { 2265 printleader(tcp); 2266 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status)); 2267 line_ended(); 2268 } 2269 droptcb(tcp); 2270 continue; 2271 } 2272 if (!WIFSTOPPED(status)) { 2273 fprintf(stderr, "PANIC: pid %u not stopped\n", pid); 2274 droptcb(tcp); 2275 continue; 2276 } 2277 2278 /* Is this the very first time we see this tracee stopped? */ 2279 if (tcp->flags & TCB_STARTUP) { 2280 if (debug_flag) 2281 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n", tcp->pid); 2282 tcp->flags &= ~TCB_STARTUP; 2283 if (tcp->flags & TCB_BPTSET) { 2284 /* 2285 * One example is a breakpoint inherited from 2286 * parent through fork(). 2287 */ 2288 if (clearbpt(tcp) < 0) { 2289 /* Pretty fatal */ 2290 droptcb(tcp); 2291 exit_code = 1; 2292 return; 2293 } 2294 } 2295 if (!use_seize && ptrace_setoptions) { 2296 if (debug_flag) 2297 fprintf(stderr, "setting opts 0x%x on pid %d\n", ptrace_setoptions, tcp->pid); 2298 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) { 2299 if (errno != ESRCH) { 2300 /* Should never happen, really */ 2301 perror_msg_and_die("PTRACE_SETOPTIONS"); 2302 } 2303 } 2304 } 2305 } 2306 2307 sig = WSTOPSIG(status); 2308 2309 if (event != 0) { 2310 /* Ptrace event */ 2311#if USE_SEIZE 2312 if (event == PTRACE_EVENT_STOP) { 2313 /* 2314 * PTRACE_INTERRUPT-stop or group-stop. 2315 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here. 2316 */ 2317 if (sig == SIGSTOP 2318 || sig == SIGTSTP 2319 || sig == SIGTTIN 2320 || sig == SIGTTOU 2321 ) { 2322 stopped = 1; 2323 goto show_stopsig; 2324 } 2325 } 2326#endif 2327 goto restart_tracee_with_sig_0; 2328 } 2329 2330 /* Is this post-attach SIGSTOP? 2331 * Interestingly, the process may stop 2332 * with STOPSIG equal to some other signal 2333 * than SIGSTOP if we happend to attach 2334 * just before the process takes a signal. 2335 */ 2336 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) { 2337 if (debug_flag) 2338 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid); 2339 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP; 2340 goto restart_tracee_with_sig_0; 2341 } 2342 2343 if (sig != syscall_trap_sig) { 2344 siginfo_t si; 2345 2346 /* Nonzero (true) if tracee is stopped by signal 2347 * (as opposed to "tracee received signal"). 2348 * TODO: shouldn't we check for errno == EINVAL too? 2349 * We can get ESRCH instead, you know... 2350 */ 2351 stopped = (ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0); 2352#if USE_SEIZE 2353 show_stopsig: 2354#endif 2355 if (cflag != CFLAG_ONLY_STATS 2356 && !hide_log_until_execve 2357 && (qual_flags[sig] & QUAL_SIGNAL) 2358 ) { 2359 printleader(tcp); 2360 if (!stopped) { 2361 tprintf("--- %s ", signame(sig)); 2362 printsiginfo(&si, verbose(tcp)); 2363 tprints(" ---\n"); 2364 } else 2365 tprintf("--- stopped by %s ---\n", 2366 signame(sig)); 2367 line_ended(); 2368 } 2369 2370 if (!stopped) 2371 /* It's signal-delivery-stop. Inject the signal */ 2372 goto restart_tracee; 2373 2374 /* It's group-stop */ 2375 if (use_seize) { 2376 /* 2377 * This ends ptrace-stop, but does *not* end group-stop. 2378 * This makes stopping signals work properly on straced process 2379 * (that is, process really stops. It used to continue to run). 2380 */ 2381 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) { 2382 /* Note: ptrace_restart emitted error message */ 2383 exit_code = 1; 2384 return; 2385 } 2386 continue; 2387 } 2388 /* We don't have PTRACE_LISTEN support... */ 2389 goto restart_tracee; 2390 } 2391 2392 /* We handled quick cases, we are permitted to interrupt now. */ 2393 if (interrupted) 2394 return; 2395 2396 /* This should be syscall entry or exit. 2397 * (Or it still can be that pesky post-execve SIGTRAP!) 2398 * Handle it. 2399 */ 2400 if (trace_syscall(tcp) < 0) { 2401 /* ptrace() failed in trace_syscall(). 2402 * Likely a result of process disappearing mid-flight. 2403 * Observed case: exit_group() or SIGKILL terminating 2404 * all processes in thread group. 2405 * We assume that ptrace error was caused by process death. 2406 * We used to detach(tcp) here, but since we no longer 2407 * implement "detach before death" policy/hack, 2408 * we can let this process to report its death to us 2409 * normally, via WIFEXITED or WIFSIGNALED wait status. 2410 */ 2411 continue; 2412 } 2413 restart_tracee_with_sig_0: 2414 sig = 0; 2415 restart_tracee: 2416 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) { 2417 /* Note: ptrace_restart emitted error message */ 2418 exit_code = 1; 2419 return; 2420 } 2421 } /* while (1) */ 2422} 2423 2424int 2425main(int argc, char *argv[]) 2426{ 2427 init(argc, argv); 2428 2429 /* Run main tracing loop */ 2430 trace(); 2431 2432 cleanup(); 2433 fflush(NULL); 2434 if (shared_log != stderr) 2435 fclose(shared_log); 2436 if (popen_pid) { 2437 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR) 2438 ; 2439 } 2440 if (exit_code > 0xff) { 2441 /* Avoid potential core file clobbering. */ 2442 struct_rlimit rlim = {0, 0}; 2443 set_rlimit(RLIMIT_CORE, &rlim); 2444 2445 /* Child was killed by a signal, mimic that. */ 2446 exit_code &= 0xff; 2447 signal(exit_code, SIG_DFL); 2448 raise(exit_code); 2449 /* Paranoia - what if this signal is not fatal? 2450 Exit with 128 + signo then. */ 2451 exit_code += 128; 2452 } 2453 2454 return exit_code; 2455} 2456