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 46#include "ptrace.h" 47 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 77const unsigned int syscall_trap_sig = SIGTRAP | 0x80; 78 79cflag_t cflag = CFLAG_NONE; 80unsigned int followfork = 0; 81unsigned int ptrace_setoptions = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC; 82unsigned int xflag = 0; 83bool debug_flag = 0; 84bool Tflag = 0; 85bool iflag = 0; 86bool count_wallclock = 0; 87unsigned int qflag = 0; 88static unsigned int tflag = 0; 89static bool rflag = 0; 90static bool print_pid_pfx = 0; 91 92/* -I n */ 93enum { 94 INTR_NOT_SET = 0, 95 INTR_ANYWHERE = 1, /* don't block/ignore any signals */ 96 INTR_WHILE_WAIT = 2, /* block fatal signals while decoding syscall. default */ 97 INTR_NEVER = 3, /* block fatal signals. default if '-o FILE PROG' */ 98 INTR_BLOCK_TSTP_TOO = 4, /* block fatal signals and SIGTSTP (^Z) */ 99 NUM_INTR_OPTS 100}; 101static int opt_intr; 102/* We play with signal mask only if this mode is active: */ 103#define interactive (opt_intr == INTR_WHILE_WAIT) 104 105/* 106 * daemonized_tracer supports -D option. 107 * With this option, strace forks twice. 108 * Unlike normal case, with -D *grandparent* process exec's, 109 * becoming a traced process. Child exits (this prevents traced process 110 * from having children it doesn't expect to have), and grandchild 111 * attaches to grandparent similarly to strace -p PID. 112 * This allows for more transparent interaction in cases 113 * when process and its parent are communicating via signals, 114 * wait() etc. Without -D, strace process gets lodged in between, 115 * disrupting parent<->child link. 116 */ 117static bool daemonized_tracer = 0; 118 119#if USE_SEIZE 120static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP; 121# define use_seize (post_attach_sigstop == 0) 122#else 123# define post_attach_sigstop TCB_IGNORE_ONE_SIGSTOP 124# define use_seize 0 125#endif 126 127/* Sometimes we want to print only succeeding syscalls. */ 128bool not_failing_only = 0; 129 130/* Show path associated with fd arguments */ 131unsigned int show_fd_path = 0; 132 133static bool detach_on_execve = 0; 134/* Are we "strace PROG" and need to skip detach on first execve? */ 135static bool skip_one_b_execve = 0; 136/* Are we "strace PROG" and need to hide everything until execve? */ 137bool hide_log_until_execve = 0; 138 139static int exit_code = 0; 140static int strace_child = 0; 141static int strace_tracer_pid = 0; 142 143static char *username = NULL; 144static uid_t run_uid; 145static gid_t run_gid; 146 147unsigned int max_strlen = DEFAULT_STRLEN; 148static int acolumn = DEFAULT_ACOLUMN; 149static char *acolumn_spaces; 150 151static char *outfname = NULL; 152/* If -ff, points to stderr. Else, it's our common output log */ 153static FILE *shared_log; 154 155struct tcb *printing_tcp = NULL; 156static struct tcb *current_tcp; 157 158static struct tcb **tcbtab; 159static unsigned int nprocs, tcbtabsize; 160static const char *progname; 161 162unsigned os_release; /* generated from uname()'s u.release */ 163 164static void detach(struct tcb *tcp); 165static void cleanup(void); 166static void interrupt(int sig); 167static sigset_t empty_set, blocked_set; 168 169#ifdef HAVE_SIG_ATOMIC_T 170static volatile sig_atomic_t interrupted; 171#else 172static volatile int interrupted; 173#endif 174 175#ifndef HAVE_STRERROR 176 177#if !HAVE_DECL_SYS_ERRLIST 178extern int sys_nerr; 179extern char *sys_errlist[]; 180#endif 181 182const char * 183strerror(int err_no) 184{ 185 static char buf[sizeof("Unknown error %d") + sizeof(int)*3]; 186 187 if (err_no < 1 || err_no >= sys_nerr) { 188 sprintf(buf, "Unknown error %d", err_no); 189 return buf; 190 } 191 return sys_errlist[err_no]; 192} 193 194#endif /* HAVE_STERRROR */ 195 196static void 197usage(FILE *ofp, int exitval) 198{ 199 fprintf(ofp, "\ 200usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\ 201 [-a column] [-o file] [-s strsize] [-P path]...\n\ 202 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 203 or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\ 204 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\ 205-c -- count time, calls, and errors for each syscall and report summary\n\ 206-C -- like -c but also print regular output\n\ 207-w -- summarise syscall latency (default is system time)\n\ 208-d -- enable debug output to stderr\n\ 209-D -- run tracer process as a detached grandchild, not as parent\n\ 210-f -- follow forks, -ff -- with output into separate files\n\ 211-i -- print instruction pointer at time of syscall\n\ 212-q -- suppress messages about attaching, detaching, etc.\n\ 213-r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs\n\ 214-T -- print time spent in each syscall\n\ 215-v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\ 216-x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\ 217-y -- print paths associated with file descriptor arguments\n\ 218-yy -- print ip:port pairs associated with socket file descriptors\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 ATTRIBUTE_NORETURN 255die(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 unsigned 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 unsigned 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 /* 769 * Linux wrongly insists the child be stopped 770 * before detaching. Arghh. We go through hoops 771 * to make a clean break of things. 772 */ 773#if defined(SPARC) 774# undef PTRACE_DETACH 775# define PTRACE_DETACH PTRACE_SUNDETACH 776#endif 777 778 if (!(tcp->flags & TCB_ATTACHED)) 779 goto drop; 780 781 /* We attached but possibly didn't see the expected SIGSTOP. 782 * We must catch exactly one as otherwise the detached process 783 * would be left stopped (process state T). 784 */ 785 if (tcp->flags & TCB_IGNORE_ONE_SIGSTOP) 786 goto wait_loop; 787 788 error = ptrace(PTRACE_DETACH, tcp->pid, 0, 0); 789 if (!error) { 790 /* On a clear day, you can see forever. */ 791 goto drop; 792 } 793 if (errno != ESRCH) { 794 /* Shouldn't happen. */ 795 perror_msg("detach: ptrace(PTRACE_DETACH,%u)", tcp->pid); 796 goto drop; 797 } 798 /* ESRCH: process is either not stopped or doesn't exist. */ 799 if (my_tkill(tcp->pid, 0) < 0) { 800 if (errno != ESRCH) 801 /* Shouldn't happen. */ 802 perror_msg("detach: tkill(%u,0)", tcp->pid); 803 /* else: process doesn't exist. */ 804 goto drop; 805 } 806 /* Process is not stopped, need to stop it. */ 807 if (use_seize) { 808 /* 809 * With SEIZE, tracee can be in group-stop already. 810 * In this state sending it another SIGSTOP does nothing. 811 * Need to use INTERRUPT. 812 * Testcase: trying to ^C a "strace -p <stopped_process>". 813 */ 814 error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0); 815 if (!error) 816 goto wait_loop; 817 if (errno != ESRCH) 818 perror_msg("detach: ptrace(PTRACE_INTERRUPT,%u)", tcp->pid); 819 } 820 else { 821 error = my_tkill(tcp->pid, SIGSTOP); 822 if (!error) 823 goto wait_loop; 824 if (errno != ESRCH) 825 perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid); 826 } 827 /* Either process doesn't exist, or some weird error. */ 828 goto drop; 829 830 wait_loop: 831 /* We end up here in three cases: 832 * 1. We sent PTRACE_INTERRUPT (use_seize case) 833 * 2. We sent SIGSTOP (!use_seize) 834 * 3. Attach SIGSTOP was already pending (TCB_IGNORE_ONE_SIGSTOP set) 835 */ 836 for (;;) { 837 unsigned int sig; 838 if (waitpid(tcp->pid, &status, __WALL) < 0) { 839 if (errno == EINTR) 840 continue; 841 /* 842 * if (errno == ECHILD) break; 843 * ^^^ WRONG! We expect this PID to exist, 844 * and want to emit a message otherwise: 845 */ 846 perror_msg("detach: waitpid(%u)", tcp->pid); 847 break; 848 } 849 if (!WIFSTOPPED(status)) { 850 /* 851 * Tracee exited or was killed by signal. 852 * We shouldn't normally reach this place: 853 * we don't want to consume exit status. 854 * Consider "strace -p PID" being ^C-ed: 855 * we want merely to detach from PID. 856 * 857 * However, we _can_ end up here if tracee 858 * was SIGKILLed. 859 */ 860 break; 861 } 862 sig = WSTOPSIG(status); 863 if (debug_flag) 864 fprintf(stderr, "detach wait: event:%d sig:%d\n", 865 (unsigned)status >> 16, sig); 866 if (use_seize) { 867 unsigned event = (unsigned)status >> 16; 868 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) { 869 /* 870 * sig == SIGTRAP: PTRACE_INTERRUPT stop. 871 * sig == other: process was already stopped 872 * with this stopping sig (see tests/detach-stopped). 873 * Looks like re-injecting this sig is not necessary 874 * in DETACH for the tracee to remain stopped. 875 */ 876 sig = 0; 877 } 878 /* 879 * PTRACE_INTERRUPT is not guaranteed to produce 880 * the above event if other ptrace-stop is pending. 881 * See tests/detach-sleeping testcase: 882 * strace got SIGINT while tracee is sleeping. 883 * We sent PTRACE_INTERRUPT. 884 * We see syscall exit, not PTRACE_INTERRUPT stop. 885 * We won't get PTRACE_INTERRUPT stop 886 * if we would CONT now. Need to DETACH. 887 */ 888 if (sig == syscall_trap_sig) 889 sig = 0; 890 /* else: not sure in which case we can be here. 891 * Signal stop? Inject it while detaching. 892 */ 893 ptrace_restart(PTRACE_DETACH, tcp, sig); 894 break; 895 } 896 /* Note: this check has to be after use_seize check */ 897 /* (else, in use_seize case SIGSTOP will be mistreated) */ 898 if (sig == SIGSTOP) { 899 /* Detach, suppressing SIGSTOP */ 900 ptrace_restart(PTRACE_DETACH, tcp, 0); 901 break; 902 } 903 if (sig == syscall_trap_sig) 904 sig = 0; 905 /* Can't detach just yet, may need to wait for SIGSTOP */ 906 error = ptrace_restart(PTRACE_CONT, tcp, sig); 907 if (error < 0) { 908 /* Should not happen. 909 * Note: ptrace_restart returns 0 on ESRCH, so it's not it. 910 * ptrace_restart already emitted error message. 911 */ 912 break; 913 } 914 } 915 916 drop: 917 if (!qflag && (tcp->flags & TCB_ATTACHED)) 918 fprintf(stderr, "Process %u detached\n", tcp->pid); 919 920 droptcb(tcp); 921} 922 923static void 924process_opt_p_list(char *opt) 925{ 926 while (*opt) { 927 /* 928 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`". 929 * pidof uses space as delim, pgrep uses newline. :( 930 */ 931 int pid; 932 char *delim = opt + strcspn(opt, ", \n\t"); 933 char c = *delim; 934 935 *delim = '\0'; 936 pid = string_to_uint(opt); 937 if (pid <= 0) { 938 error_msg_and_die("Invalid process id: '%s'", opt); 939 } 940 if (pid == strace_tracer_pid) { 941 error_msg_and_die("I'm sorry, I can't let you do that, Dave."); 942 } 943 *delim = c; 944 alloctcb(pid); 945 if (c == '\0') 946 break; 947 opt = delim + 1; 948 } 949} 950 951static void 952startup_attach(void) 953{ 954 unsigned int tcbi; 955 struct tcb *tcp; 956 957 /* 958 * Block user interruptions as we would leave the traced 959 * process stopped (process state T) if we would terminate in 960 * between PTRACE_ATTACH and wait4() on SIGSTOP. 961 * We rely on cleanup() from this point on. 962 */ 963 if (interactive) 964 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 965 966 if (daemonized_tracer) { 967 pid_t pid = fork(); 968 if (pid < 0) { 969 perror_msg_and_die("fork"); 970 } 971 if (pid) { /* parent */ 972 /* 973 * Wait for grandchild to attach to straced process 974 * (grandparent). Grandchild SIGKILLs us after it attached. 975 * Grandparent's wait() is unblocked by our death, 976 * it proceeds to exec the straced program. 977 */ 978 pause(); 979 _exit(0); /* paranoia */ 980 } 981 /* grandchild */ 982 /* We will be the tracer process. Remember our new pid: */ 983 strace_tracer_pid = getpid(); 984 } 985 986 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) { 987 tcp = tcbtab[tcbi]; 988 989 if (!tcp->pid) 990 continue; 991 992 /* Is this a process we should attach to, but not yet attached? */ 993 if (tcp->flags & TCB_ATTACHED) 994 continue; /* no, we already attached it */ 995 996 if (followfork && !daemonized_tracer) { 997 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3]; 998 DIR *dir; 999 1000 sprintf(procdir, "/proc/%d/task", tcp->pid); 1001 dir = opendir(procdir); 1002 if (dir != NULL) { 1003 unsigned int ntid = 0, nerr = 0; 1004 struct_dirent *de; 1005 1006 while ((de = read_dir(dir)) != NULL) { 1007 struct tcb *cur_tcp; 1008 int tid; 1009 1010 if (de->d_fileno == 0) 1011 continue; 1012 /* we trust /proc filesystem */ 1013 tid = atoi(de->d_name); 1014 if (tid <= 0) 1015 continue; 1016 ++ntid; 1017 if (ptrace_attach_or_seize(tid) < 0) { 1018 ++nerr; 1019 if (debug_flag) 1020 fprintf(stderr, "attach to pid %d failed\n", tid); 1021 continue; 1022 } 1023 if (debug_flag) 1024 fprintf(stderr, "attach to pid %d succeeded\n", tid); 1025 cur_tcp = tcp; 1026 if (tid != tcp->pid) 1027 cur_tcp = alloctcb(tid); 1028 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1029 newoutf(cur_tcp); 1030 } 1031 closedir(dir); 1032 if (interactive) { 1033 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1034 if (interrupted) 1035 goto ret; 1036 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 1037 } 1038 ntid -= nerr; 1039 if (ntid == 0) { 1040 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1041 droptcb(tcp); 1042 continue; 1043 } 1044 if (!qflag) { 1045 fprintf(stderr, ntid > 1 1046? "Process %u attached with %u threads\n" 1047: "Process %u attached\n", 1048 tcp->pid, ntid); 1049 } 1050 if (!(tcp->flags & TCB_ATTACHED)) { 1051 /* -p PID, we failed to attach to PID itself 1052 * but did attach to some of its sibling threads. 1053 * Drop PID's tcp. 1054 */ 1055 droptcb(tcp); 1056 } 1057 continue; 1058 } /* if (opendir worked) */ 1059 } /* if (-f) */ 1060 if (ptrace_attach_or_seize(tcp->pid) < 0) { 1061 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)"); 1062 droptcb(tcp); 1063 continue; 1064 } 1065 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1066 newoutf(tcp); 1067 if (debug_flag) 1068 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid); 1069 1070 if (daemonized_tracer) { 1071 /* 1072 * Make parent go away. 1073 * Also makes grandparent's wait() unblock. 1074 */ 1075 kill(getppid(), SIGKILL); 1076 } 1077 1078 if (!qflag) 1079 fprintf(stderr, 1080 "Process %u attached\n", 1081 tcp->pid); 1082 } /* for each tcbtab[] */ 1083 1084 ret: 1085 if (interactive) 1086 sigprocmask(SIG_SETMASK, &empty_set, NULL); 1087} 1088 1089/* Stack-o-phobic exec helper, in the hope to work around 1090 * NOMMU + "daemonized tracer" difficulty. 1091 */ 1092struct exec_params { 1093 int fd_to_close; 1094 uid_t run_euid; 1095 gid_t run_egid; 1096 char **argv; 1097 char *pathname; 1098}; 1099static struct exec_params params_for_tracee; 1100 1101static void ATTRIBUTE_NOINLINE ATTRIBUTE_NORETURN 1102exec_or_die(void) 1103{ 1104 struct exec_params *params = ¶ms_for_tracee; 1105 1106 if (params->fd_to_close >= 0) 1107 close(params->fd_to_close); 1108 if (!daemonized_tracer && !use_seize) { 1109 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) { 1110 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)"); 1111 } 1112 } 1113 1114 if (username != NULL) { 1115 /* 1116 * It is important to set groups before we 1117 * lose privileges on setuid. 1118 */ 1119 if (initgroups(username, run_gid) < 0) { 1120 perror_msg_and_die("initgroups"); 1121 } 1122 if (setregid(run_gid, params->run_egid) < 0) { 1123 perror_msg_and_die("setregid"); 1124 } 1125 if (setreuid(run_uid, params->run_euid) < 0) { 1126 perror_msg_and_die("setreuid"); 1127 } 1128 } 1129 else if (geteuid() != 0) 1130 if (setreuid(run_uid, run_uid) < 0) { 1131 perror_msg_and_die("setreuid"); 1132 } 1133 1134 if (!daemonized_tracer) { 1135 /* 1136 * Induce a ptrace stop. Tracer (our parent) 1137 * will resume us with PTRACE_SYSCALL and display 1138 * the immediately following execve syscall. 1139 * Can't do this on NOMMU systems, we are after 1140 * vfork: parent is blocked, stopping would deadlock. 1141 */ 1142 if (!NOMMU_SYSTEM) 1143 kill(getpid(), SIGSTOP); 1144 } else { 1145 alarm(3); 1146 /* we depend on SIGCHLD set to SIG_DFL by init code */ 1147 /* if it happens to be SIG_IGN'ed, wait won't block */ 1148 wait(NULL); 1149 alarm(0); 1150 } 1151 1152 execv(params->pathname, params->argv); 1153 perror_msg_and_die("exec"); 1154} 1155 1156static void 1157startup_child(char **argv) 1158{ 1159 struct_stat statbuf; 1160 const char *filename; 1161 size_t filename_len; 1162 char pathname[PATH_MAX]; 1163 int pid; 1164 struct tcb *tcp; 1165 1166 filename = argv[0]; 1167 filename_len = strlen(filename); 1168 1169 if (filename_len > sizeof(pathname) - 1) { 1170 errno = ENAMETOOLONG; 1171 perror_msg_and_die("exec"); 1172 } 1173 if (strchr(filename, '/')) { 1174 strcpy(pathname, filename); 1175 } 1176#ifdef USE_DEBUGGING_EXEC 1177 /* 1178 * Debuggers customarily check the current directory 1179 * first regardless of the path but doing that gives 1180 * security geeks a panic attack. 1181 */ 1182 else if (stat_file(filename, &statbuf) == 0) 1183 strcpy(pathname, filename); 1184#endif /* USE_DEBUGGING_EXEC */ 1185 else { 1186 const char *path; 1187 size_t m, n, len; 1188 1189 for (path = getenv("PATH"); path && *path; path += m) { 1190 const char *colon = strchr(path, ':'); 1191 if (colon) { 1192 n = colon - path; 1193 m = n + 1; 1194 } 1195 else 1196 m = n = strlen(path); 1197 if (n == 0) { 1198 if (!getcwd(pathname, PATH_MAX)) 1199 continue; 1200 len = strlen(pathname); 1201 } 1202 else if (n > sizeof pathname - 1) 1203 continue; 1204 else { 1205 strncpy(pathname, path, n); 1206 len = n; 1207 } 1208 if (len && pathname[len - 1] != '/') 1209 pathname[len++] = '/'; 1210 if (filename_len + len > sizeof(pathname) - 1) 1211 continue; 1212 strcpy(pathname + len, filename); 1213 if (stat_file(pathname, &statbuf) == 0 && 1214 /* Accept only regular files 1215 with some execute bits set. 1216 XXX not perfect, might still fail */ 1217 S_ISREG(statbuf.st_mode) && 1218 (statbuf.st_mode & 0111)) 1219 break; 1220 } 1221 if (!path || !*path) 1222 pathname[0] = '\0'; 1223 } 1224 if (stat_file(pathname, &statbuf) < 0) { 1225 perror_msg_and_die("Can't stat '%s'", filename); 1226 } 1227 1228 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1; 1229 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid; 1230 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid; 1231 params_for_tracee.argv = argv; 1232 /* 1233 * On NOMMU, can be safely freed only after execve in tracee. 1234 * It's hard to know when that happens, so we just leak it. 1235 */ 1236 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname; 1237 1238#if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY 1239 if (daemonized_tracer) 1240 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY); 1241#endif 1242 1243 pid = fork(); 1244 if (pid < 0) { 1245 perror_msg_and_die("fork"); 1246 } 1247 if ((pid != 0 && daemonized_tracer) 1248 || (pid == 0 && !daemonized_tracer) 1249 ) { 1250 /* We are to become the tracee. Two cases: 1251 * -D: we are parent 1252 * not -D: we are child 1253 */ 1254 exec_or_die(); 1255 } 1256 1257 /* We are the tracer */ 1258 1259 if (!daemonized_tracer) { 1260 strace_child = pid; 1261 if (!use_seize) { 1262 /* child did PTRACE_TRACEME, nothing to do in parent */ 1263 } else { 1264 if (!NOMMU_SYSTEM) { 1265 /* Wait until child stopped itself */ 1266 int status; 1267 while (waitpid(pid, &status, WSTOPPED) < 0) { 1268 if (errno == EINTR) 1269 continue; 1270 perror_msg_and_die("waitpid"); 1271 } 1272 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) { 1273 kill_save_errno(pid, SIGKILL); 1274 perror_msg_and_die("Unexpected wait status %x", status); 1275 } 1276 } 1277 /* Else: NOMMU case, we have no way to sync. 1278 * Just attach to it as soon as possible. 1279 * This means that we may miss a few first syscalls... 1280 */ 1281 1282 if (ptrace_attach_or_seize(pid)) { 1283 kill_save_errno(pid, SIGKILL); 1284 perror_msg_and_die("Can't attach to %d", pid); 1285 } 1286 if (!NOMMU_SYSTEM) 1287 kill(pid, SIGCONT); 1288 } 1289 tcp = alloctcb(pid); 1290 if (!NOMMU_SYSTEM) 1291 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1292 else 1293 tcp->flags |= TCB_ATTACHED | TCB_STARTUP; 1294 newoutf(tcp); 1295 } 1296 else { 1297 /* With -D, we are *child* here, IOW: different pid. Fetch it: */ 1298 strace_tracer_pid = getpid(); 1299 /* The tracee is our parent: */ 1300 pid = getppid(); 1301 alloctcb(pid); 1302 /* attaching will be done later, by startup_attach */ 1303 /* note: we don't do newoutf(tcp) here either! */ 1304 1305 /* NOMMU BUG! -D mode is active, we (child) return, 1306 * and we will scribble over parent's stack! 1307 * When parent later unpauses, it segfaults. 1308 * 1309 * We work around it 1310 * (1) by declaring exec_or_die() NORETURN, 1311 * hopefully compiler will just jump to it 1312 * instead of call (won't push anything to stack), 1313 * (2) by trying very hard in exec_or_die() 1314 * to not use any stack, 1315 * (3) having a really big (PATH_MAX) stack object 1316 * in this function, which creates a "buffer" between 1317 * child's and parent's stack pointers. 1318 * This may save us if (1) and (2) failed 1319 * and compiler decided to use stack in exec_or_die() anyway 1320 * (happens on i386 because of stack parameter passing). 1321 * 1322 * A cleaner solution is to use makecontext + setcontext 1323 * to create a genuine separate stack and execute on it. 1324 */ 1325 } 1326} 1327 1328#if USE_SEIZE 1329static void 1330test_ptrace_seize(void) 1331{ 1332 int pid; 1333 1334 /* Need fork for test. NOMMU has no forks */ 1335 if (NOMMU_SYSTEM) { 1336 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1337 return; 1338 } 1339 1340 pid = fork(); 1341 if (pid < 0) 1342 perror_msg_and_die("fork"); 1343 1344 if (pid == 0) { 1345 pause(); 1346 _exit(0); 1347 } 1348 1349 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After 1350 * attaching tracee continues to run unless a trap condition occurs. 1351 * PTRACE_SEIZE doesn't affect signal or group stop state. 1352 */ 1353 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) { 1354 post_attach_sigstop = 0; /* this sets use_seize to 1 */ 1355 } else if (debug_flag) { 1356 fprintf(stderr, "PTRACE_SEIZE doesn't work\n"); 1357 } 1358 1359 kill(pid, SIGKILL); 1360 1361 while (1) { 1362 int status, tracee_pid; 1363 1364 errno = 0; 1365 tracee_pid = waitpid(pid, &status, 0); 1366 if (tracee_pid <= 0) { 1367 if (errno == EINTR) 1368 continue; 1369 perror_msg_and_die("%s: unexpected wait result %d", 1370 __func__, tracee_pid); 1371 } 1372 if (WIFSIGNALED(status)) { 1373 return; 1374 } 1375 error_msg_and_die("%s: unexpected wait status %x", 1376 __func__, status); 1377 } 1378} 1379#else /* !USE_SEIZE */ 1380# define test_ptrace_seize() ((void)0) 1381#endif 1382 1383static unsigned 1384get_os_release(void) 1385{ 1386 unsigned rel; 1387 const char *p; 1388 struct utsname u; 1389 if (uname(&u) < 0) 1390 perror_msg_and_die("uname"); 1391 /* u.release has this form: "3.2.9[-some-garbage]" */ 1392 rel = 0; 1393 p = u.release; 1394 for (;;) { 1395 if (!(*p >= '0' && *p <= '9')) 1396 error_msg_and_die("Bad OS release string: '%s'", u.release); 1397 /* Note: this open-codes KERNEL_VERSION(): */ 1398 rel = (rel << 8) | atoi(p); 1399 if (rel >= KERNEL_VERSION(1,0,0)) 1400 break; 1401 while (*p >= '0' && *p <= '9') 1402 p++; 1403 if (*p != '.') { 1404 if (rel >= KERNEL_VERSION(0,1,0)) { 1405 /* "X.Y-something" means "X.Y.0" */ 1406 rel <<= 8; 1407 break; 1408 } 1409 error_msg_and_die("Bad OS release string: '%s'", u.release); 1410 } 1411 p++; 1412 } 1413 return rel; 1414} 1415 1416/* 1417 * Initialization part of main() was eating much stack (~0.5k), 1418 * which was unused after init. 1419 * We can reuse it if we move init code into a separate function. 1420 * 1421 * Don't want main() to inline us and defeat the reason 1422 * we have a separate function. 1423 */ 1424static void ATTRIBUTE_NOINLINE 1425init(int argc, char *argv[]) 1426{ 1427 struct tcb *tcp; 1428 int c, i; 1429 int optF = 0; 1430 unsigned int tcbi; 1431 struct sigaction sa; 1432 1433 progname = argv[0] ? argv[0] : "strace"; 1434 1435 /* Make sure SIGCHLD has the default action so that waitpid 1436 definitely works without losing track of children. The user 1437 should not have given us a bogus state to inherit, but he might 1438 have. Arguably we should detect SIG_IGN here and pass it on 1439 to children, but probably noone really needs that. */ 1440 signal(SIGCHLD, SIG_DFL); 1441 1442 strace_tracer_pid = getpid(); 1443 1444 os_release = get_os_release(); 1445 1446 /* Allocate the initial tcbtab. */ 1447 tcbtabsize = argc; /* Surely enough for all -p args. */ 1448 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0])); 1449 if (!tcbtab) 1450 die_out_of_memory(); 1451 tcp = calloc(tcbtabsize, sizeof(*tcp)); 1452 if (!tcp) 1453 die_out_of_memory(); 1454 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) 1455 tcbtab[tcbi] = tcp++; 1456 1457 shared_log = stderr; 1458 set_sortby(DEFAULT_SORTBY); 1459 set_personality(DEFAULT_PERSONALITY); 1460 qualify("trace=all"); 1461 qualify("abbrev=all"); 1462 qualify("verbose=all"); 1463#if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE) 1464# error Bug in DEFAULT_QUAL_FLAGS 1465#endif 1466 qualify("signal=all"); 1467 while ((c = getopt(argc, argv, 1468 "+b:cCdfFhiqrtTvVwxyz" 1469#ifdef USE_LIBUNWIND 1470 "k" 1471#endif 1472 "D" 1473 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) { 1474 switch (c) { 1475 case 'b': 1476 if (strcmp(optarg, "execve") != 0) 1477 error_msg_and_die("Syscall '%s' for -b isn't supported", 1478 optarg); 1479 detach_on_execve = 1; 1480 break; 1481 case 'c': 1482 if (cflag == CFLAG_BOTH) { 1483 error_msg_and_die("-c and -C are mutually exclusive"); 1484 } 1485 cflag = CFLAG_ONLY_STATS; 1486 break; 1487 case 'C': 1488 if (cflag == CFLAG_ONLY_STATS) { 1489 error_msg_and_die("-c and -C are mutually exclusive"); 1490 } 1491 cflag = CFLAG_BOTH; 1492 break; 1493 case 'd': 1494 debug_flag = 1; 1495 break; 1496 case 'D': 1497 daemonized_tracer = 1; 1498 break; 1499 case 'F': 1500 optF = 1; 1501 break; 1502 case 'f': 1503 followfork++; 1504 break; 1505 case 'h': 1506 usage(stdout, 0); 1507 break; 1508 case 'i': 1509 iflag = 1; 1510 break; 1511 case 'q': 1512 qflag++; 1513 break; 1514 case 'r': 1515 rflag = 1; 1516 /* fall through to tflag++ */ 1517 case 't': 1518 tflag++; 1519 break; 1520 case 'T': 1521 Tflag = 1; 1522 break; 1523 case 'w': 1524 count_wallclock = 1; 1525 break; 1526 case 'x': 1527 xflag++; 1528 break; 1529 case 'y': 1530 show_fd_path++; 1531 break; 1532 case 'v': 1533 qualify("abbrev=none"); 1534 break; 1535 case 'V': 1536 printf("%s -- version %s\n", PACKAGE_NAME, VERSION); 1537 exit(0); 1538 break; 1539 case 'z': 1540 not_failing_only = 1; 1541 break; 1542 case 'a': 1543 acolumn = string_to_uint(optarg); 1544 if (acolumn < 0) 1545 error_opt_arg(c, optarg); 1546 break; 1547 case 'e': 1548 qualify(optarg); 1549 break; 1550 case 'o': 1551 outfname = strdup(optarg); 1552 break; 1553 case 'O': 1554 i = string_to_uint(optarg); 1555 if (i < 0) 1556 error_opt_arg(c, optarg); 1557 set_overhead(i); 1558 break; 1559 case 'p': 1560 process_opt_p_list(optarg); 1561 break; 1562 case 'P': 1563 pathtrace_select(optarg); 1564 break; 1565 case 's': 1566 i = string_to_uint(optarg); 1567 if (i < 0) 1568 error_opt_arg(c, optarg); 1569 max_strlen = i; 1570 break; 1571 case 'S': 1572 set_sortby(optarg); 1573 break; 1574 case 'u': 1575 username = strdup(optarg); 1576 break; 1577#ifdef USE_LIBUNWIND 1578 case 'k': 1579 stack_trace_enabled = true; 1580 break; 1581#endif 1582 case 'E': 1583 if (putenv(optarg) < 0) 1584 die_out_of_memory(); 1585 break; 1586 case 'I': 1587 opt_intr = string_to_uint(optarg); 1588 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS) 1589 error_opt_arg(c, optarg); 1590 break; 1591 default: 1592 usage(stderr, 1); 1593 break; 1594 } 1595 } 1596 argv += optind; 1597 /* argc -= optind; - no need, argc is not used below */ 1598 1599 acolumn_spaces = malloc(acolumn + 1); 1600 if (!acolumn_spaces) 1601 die_out_of_memory(); 1602 memset(acolumn_spaces, ' ', acolumn); 1603 acolumn_spaces[acolumn] = '\0'; 1604 1605 /* Must have PROG [ARGS], or -p PID. Not both. */ 1606 if (!argv[0] == !nprocs) 1607 usage(stderr, 1); 1608 1609 if (nprocs != 0 && daemonized_tracer) { 1610 error_msg_and_die("-D and -p are mutually exclusive"); 1611 } 1612 1613 if (!followfork) 1614 followfork = optF; 1615 1616 if (followfork >= 2 && cflag) { 1617 error_msg_and_die("(-c or -C) and -ff are mutually exclusive"); 1618 } 1619 1620 if (count_wallclock && !cflag) { 1621 error_msg_and_die("-w must be given with (-c or -C)"); 1622 } 1623 1624 if (cflag == CFLAG_ONLY_STATS) { 1625 if (iflag) 1626 error_msg("-%c has no effect with -c", 'i'); 1627#ifdef USE_LIBUNWIND 1628 if (stack_trace_enabled) 1629 error_msg("-%c has no effect with -c", 'k'); 1630#endif 1631 if (rflag) 1632 error_msg("-%c has no effect with -c", 'r'); 1633 if (tflag) 1634 error_msg("-%c has no effect with -c", 't'); 1635 if (Tflag) 1636 error_msg("-%c has no effect with -c", 'T'); 1637 if (show_fd_path) 1638 error_msg("-%c has no effect with -c", 'y'); 1639 } 1640 1641#ifdef USE_LIBUNWIND 1642 if (stack_trace_enabled) 1643 unwind_init(); 1644#endif 1645 1646 /* See if they want to run as another user. */ 1647 if (username != NULL) { 1648 struct passwd *pent; 1649 1650 if (getuid() != 0 || geteuid() != 0) { 1651 error_msg_and_die("You must be root to use the -u option"); 1652 } 1653 pent = getpwnam(username); 1654 if (pent == NULL) { 1655 error_msg_and_die("Cannot find user '%s'", username); 1656 } 1657 run_uid = pent->pw_uid; 1658 run_gid = pent->pw_gid; 1659 } 1660 else { 1661 run_uid = getuid(); 1662 run_gid = getgid(); 1663 } 1664 1665 if (followfork) 1666 ptrace_setoptions |= PTRACE_O_TRACECLONE | 1667 PTRACE_O_TRACEFORK | 1668 PTRACE_O_TRACEVFORK; 1669 if (debug_flag) 1670 fprintf(stderr, "ptrace_setoptions = %#x\n", ptrace_setoptions); 1671 test_ptrace_seize(); 1672 1673 /* Check if they want to redirect the output. */ 1674 if (outfname) { 1675 /* See if they want to pipe the output. */ 1676 if (outfname[0] == '|' || outfname[0] == '!') { 1677 /* 1678 * We can't do the <outfname>.PID funny business 1679 * when using popen, so prohibit it. 1680 */ 1681 if (followfork >= 2) 1682 error_msg_and_die("Piping the output and -ff are mutually exclusive"); 1683 shared_log = strace_popen(outfname + 1); 1684 } 1685 else if (followfork < 2) 1686 shared_log = strace_fopen(outfname); 1687 } else { 1688 /* -ff without -o FILE is the same as single -f */ 1689 if (followfork >= 2) 1690 followfork = 1; 1691 } 1692 1693 if (!outfname || outfname[0] == '|' || outfname[0] == '!') { 1694 char *buf = malloc(BUFSIZ); 1695 if (!buf) 1696 die_out_of_memory(); 1697 setvbuf(shared_log, buf, _IOLBF, BUFSIZ); 1698 } 1699 if (outfname && argv[0]) { 1700 if (!opt_intr) 1701 opt_intr = INTR_NEVER; 1702 qflag = 1; 1703 } 1704 if (!opt_intr) 1705 opt_intr = INTR_WHILE_WAIT; 1706 1707 /* argv[0] -pPID -oFILE Default interactive setting 1708 * yes 0 0 INTR_WHILE_WAIT 1709 * no 1 0 INTR_WHILE_WAIT 1710 * yes 0 1 INTR_NEVER 1711 * no 1 1 INTR_WHILE_WAIT 1712 */ 1713 1714 sigemptyset(&empty_set); 1715 sigemptyset(&blocked_set); 1716 1717 /* startup_child() must be called before the signal handlers get 1718 * installed below as they are inherited into the spawned process. 1719 * Also we do not need to be protected by them as during interruption 1720 * in the startup_child() mode we kill the spawned process anyway. 1721 */ 1722 if (argv[0]) { 1723 if (!NOMMU_SYSTEM || daemonized_tracer) 1724 hide_log_until_execve = 1; 1725 skip_one_b_execve = 1; 1726 startup_child(argv); 1727 } 1728 1729 sa.sa_handler = SIG_IGN; 1730 sigemptyset(&sa.sa_mask); 1731 sa.sa_flags = 0; 1732 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */ 1733 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */ 1734 if (opt_intr != INTR_ANYWHERE) { 1735 if (opt_intr == INTR_BLOCK_TSTP_TOO) 1736 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */ 1737 /* 1738 * In interactive mode (if no -o OUTFILE, or -p PID is used), 1739 * fatal signals are blocked while syscall stop is processed, 1740 * and acted on in between, when waiting for new syscall stops. 1741 * In non-interactive mode, signals are ignored. 1742 */ 1743 if (opt_intr == INTR_WHILE_WAIT) { 1744 sigaddset(&blocked_set, SIGHUP); 1745 sigaddset(&blocked_set, SIGINT); 1746 sigaddset(&blocked_set, SIGQUIT); 1747 sigaddset(&blocked_set, SIGPIPE); 1748 sigaddset(&blocked_set, SIGTERM); 1749 sa.sa_handler = interrupt; 1750 } 1751 /* SIG_IGN, or set handler for these */ 1752 sigaction(SIGHUP, &sa, NULL); 1753 sigaction(SIGINT, &sa, NULL); 1754 sigaction(SIGQUIT, &sa, NULL); 1755 sigaction(SIGPIPE, &sa, NULL); 1756 sigaction(SIGTERM, &sa, NULL); 1757 } 1758 if (nprocs != 0 || daemonized_tracer) 1759 startup_attach(); 1760 1761 /* Do we want pids printed in our -o OUTFILE? 1762 * -ff: no (every pid has its own file); or 1763 * -f: yes (there can be more pids in the future); or 1764 * -p PID1,PID2: yes (there are already more than one pid) 1765 */ 1766 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1)); 1767} 1768 1769static struct tcb * 1770pid2tcb(int pid) 1771{ 1772 unsigned int i; 1773 1774 if (pid <= 0) 1775 return NULL; 1776 1777 for (i = 0; i < tcbtabsize; i++) { 1778 struct tcb *tcp = tcbtab[i]; 1779 if (tcp->pid == pid) 1780 return tcp; 1781 } 1782 1783 return NULL; 1784} 1785 1786static void 1787cleanup(void) 1788{ 1789 unsigned int i; 1790 struct tcb *tcp; 1791 int fatal_sig; 1792 1793 /* 'interrupted' is a volatile object, fetch it only once */ 1794 fatal_sig = interrupted; 1795 if (!fatal_sig) 1796 fatal_sig = SIGTERM; 1797 1798 for (i = 0; i < tcbtabsize; i++) { 1799 tcp = tcbtab[i]; 1800 if (!tcp->pid) 1801 continue; 1802 if (debug_flag) 1803 fprintf(stderr, 1804 "cleanup: looking at pid %u\n", tcp->pid); 1805 if (tcp->pid == strace_child) { 1806 kill(tcp->pid, SIGCONT); 1807 kill(tcp->pid, fatal_sig); 1808 } 1809 detach(tcp); 1810 } 1811 if (cflag) 1812 call_summary(shared_log); 1813} 1814 1815static void 1816interrupt(int sig) 1817{ 1818 interrupted = sig; 1819} 1820 1821static void 1822print_debug_info(const int pid, int status) 1823{ 1824 const unsigned int event = (unsigned int) status >> 16; 1825 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16]; 1826 char evbuf[sizeof(",EVENT_VFORK_DONE (%u)") + sizeof(int)*3 /*paranoia:*/ + 16]; 1827 1828 strcpy(buf, "???"); 1829 if (WIFSIGNALED(status)) 1830#ifdef WCOREDUMP 1831 sprintf(buf, "WIFSIGNALED,%ssig=%s", 1832 WCOREDUMP(status) ? "core," : "", 1833 signame(WTERMSIG(status))); 1834#else 1835 sprintf(buf, "WIFSIGNALED,sig=%s", 1836 signame(WTERMSIG(status))); 1837#endif 1838 if (WIFEXITED(status)) 1839 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status)); 1840 if (WIFSTOPPED(status)) 1841 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status))); 1842#ifdef WIFCONTINUED 1843 /* Should never be seen */ 1844 if (WIFCONTINUED(status)) 1845 strcpy(buf, "WIFCONTINUED"); 1846#endif 1847 evbuf[0] = '\0'; 1848 if (event != 0) { 1849 static const char *const event_names[] = { 1850 [PTRACE_EVENT_CLONE] = "CLONE", 1851 [PTRACE_EVENT_FORK] = "FORK", 1852 [PTRACE_EVENT_VFORK] = "VFORK", 1853 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE", 1854 [PTRACE_EVENT_EXEC] = "EXEC", 1855 [PTRACE_EVENT_EXIT] = "EXIT", 1856 /* [PTRACE_EVENT_STOP (=128)] would make biggish array */ 1857 }; 1858 const char *e = "??"; 1859 if (event < ARRAY_SIZE(event_names)) 1860 e = event_names[event]; 1861 else if (event == PTRACE_EVENT_STOP) 1862 e = "STOP"; 1863 sprintf(evbuf, ",EVENT_%s (%u)", e, event); 1864 } 1865 fprintf(stderr, " [wait(0x%06x) = %u] %s%s\n", status, pid, buf, evbuf); 1866} 1867 1868static struct tcb * 1869maybe_allocate_tcb(const int pid, int status) 1870{ 1871 if (!WIFSTOPPED(status)) { 1872 if (detach_on_execve && pid == strace_child) { 1873 /* example: strace -bexecve sh -c 'exec true' */ 1874 strace_child = 0; 1875 return NULL; 1876 } 1877 /* 1878 * This can happen if we inherited an unknown child. 1879 * Example: (sleep 1 & exec strace true) 1880 */ 1881 error_msg("Exit of unknown pid %u ignored", pid); 1882 return NULL; 1883 } 1884 if (followfork) { 1885 /* We assume it's a fork/vfork/clone child */ 1886 struct tcb *tcp = alloctcb(pid); 1887 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop; 1888 newoutf(tcp); 1889 if (!qflag) 1890 fprintf(stderr, "Process %d attached\n", pid); 1891 return tcp; 1892 } else { 1893 /* This can happen if a clone call used 1894 * CLONE_PTRACE itself. 1895 */ 1896 ptrace(PTRACE_CONT, pid, (char *) 0, 0); 1897 error_msg("Stop of unknown pid %u seen, PTRACE_CONTed it", pid); 1898 return NULL; 1899 } 1900} 1901 1902static struct tcb * 1903maybe_switch_tcbs(struct tcb *tcp, const int pid) 1904{ 1905 FILE *fp; 1906 struct tcb *execve_thread; 1907 long old_pid = 0; 1908 1909 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0) 1910 return tcp; 1911 /* Avoid truncation in pid2tcb() param passing */ 1912 if (old_pid <= 0 || old_pid == pid) 1913 return tcp; 1914 if ((unsigned long) old_pid > UINT_MAX) 1915 return tcp; 1916 execve_thread = pid2tcb(old_pid); 1917 /* It should be !NULL, but I feel paranoid */ 1918 if (!execve_thread) 1919 return tcp; 1920 1921 if (execve_thread->curcol != 0) { 1922 /* 1923 * One case we are here is -ff: 1924 * try "strace -oLOG -ff test/threaded_execve" 1925 */ 1926 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid); 1927 /*execve_thread->curcol = 0; - no need, see code below */ 1928 } 1929 /* Swap output FILEs (needed for -ff) */ 1930 fp = execve_thread->outf; 1931 execve_thread->outf = tcp->outf; 1932 tcp->outf = fp; 1933 /* And their column positions */ 1934 execve_thread->curcol = tcp->curcol; 1935 tcp->curcol = 0; 1936 /* Drop leader, but close execve'd thread outfile (if -ff) */ 1937 droptcb(tcp); 1938 /* Switch to the thread, reusing leader's outfile and pid */ 1939 tcp = execve_thread; 1940 tcp->pid = pid; 1941 if (cflag != CFLAG_ONLY_STATS) { 1942 printleader(tcp); 1943 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid); 1944 line_ended(); 1945 tcp->flags |= TCB_REPRINT; 1946 } 1947 1948 return tcp; 1949} 1950 1951static void 1952print_signalled(struct tcb *tcp, const int pid, int status) 1953{ 1954 if (pid == strace_child) { 1955 exit_code = 0x100 | WTERMSIG(status); 1956 strace_child = 0; 1957 } 1958 1959 if (cflag != CFLAG_ONLY_STATS 1960 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL) 1961 ) { 1962 printleader(tcp); 1963#ifdef WCOREDUMP 1964 tprintf("+++ killed by %s %s+++\n", 1965 signame(WTERMSIG(status)), 1966 WCOREDUMP(status) ? "(core dumped) " : ""); 1967#else 1968 tprintf("+++ killed by %s +++\n", 1969 signame(WTERMSIG(status))); 1970#endif 1971 line_ended(); 1972 } 1973} 1974 1975static void 1976print_exited(struct tcb *tcp, const int pid, int status) 1977{ 1978 if (pid == strace_child) { 1979 exit_code = WEXITSTATUS(status); 1980 strace_child = 0; 1981 } 1982 1983 if (cflag != CFLAG_ONLY_STATS && 1984 qflag < 2) { 1985 printleader(tcp); 1986 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status)); 1987 line_ended(); 1988 } 1989} 1990 1991static void 1992print_stopped(struct tcb *tcp, const siginfo_t *si, const unsigned int sig) 1993{ 1994 if (cflag != CFLAG_ONLY_STATS 1995 && !hide_log_until_execve 1996 && (qual_flags[sig] & QUAL_SIGNAL) 1997 ) { 1998 printleader(tcp); 1999 if (si) { 2000 tprintf("--- %s ", signame(sig)); 2001 printsiginfo(si, verbose(tcp)); 2002 tprints(" ---\n"); 2003 } else 2004 tprintf("--- stopped by %s ---\n", signame(sig)); 2005 line_ended(); 2006 } 2007} 2008 2009static void 2010startup_tcb(struct tcb *tcp) 2011{ 2012 if (debug_flag) 2013 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n", 2014 tcp->pid); 2015 2016 tcp->flags &= ~TCB_STARTUP; 2017 2018 if (!use_seize) { 2019 if (debug_flag) 2020 fprintf(stderr, "setting opts 0x%x on pid %d\n", 2021 ptrace_setoptions, tcp->pid); 2022 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) { 2023 if (errno != ESRCH) { 2024 /* Should never happen, really */ 2025 perror_msg_and_die("PTRACE_SETOPTIONS"); 2026 } 2027 } 2028 } 2029} 2030 2031/* Returns true iff the main trace loop has to continue. */ 2032static bool 2033trace(void) 2034{ 2035 int pid; 2036 int wait_errno; 2037 int status; 2038 bool stopped; 2039 unsigned int sig; 2040 unsigned int event; 2041 struct tcb *tcp; 2042 struct rusage ru; 2043 2044 if (interrupted) 2045 return false; 2046 2047 /* 2048 * Used to exit simply when nprocs hits zero, but in this testcase: 2049 * int main() { _exit(!!fork()); } 2050 * under strace -f, parent sometimes (rarely) manages 2051 * to exit before we see the first stop of the child, 2052 * and we are losing track of it: 2053 * 19923 clone(...) = 19924 2054 * 19923 exit_group(1) = ? 2055 * 19923 +++ exited with 1 +++ 2056 * Exiting only when wait() returns ECHILD works better. 2057 */ 2058 if (popen_pid != 0) { 2059 /* However, if -o|logger is in use, we can't do that. 2060 * Can work around that by double-forking the logger, 2061 * but that loses the ability to wait for its completion 2062 * on exit. Oh well... 2063 */ 2064 if (nprocs == 0) 2065 return false; 2066 } 2067 2068 if (interactive) 2069 sigprocmask(SIG_SETMASK, &empty_set, NULL); 2070 pid = wait4(-1, &status, __WALL, (cflag ? &ru : NULL)); 2071 wait_errno = errno; 2072 if (interactive) 2073 sigprocmask(SIG_BLOCK, &blocked_set, NULL); 2074 2075 if (pid < 0) { 2076 if (wait_errno == EINTR) 2077 return true; 2078 if (nprocs == 0 && wait_errno == ECHILD) 2079 return false; 2080 /* 2081 * If nprocs > 0, ECHILD is not expected, 2082 * treat it as any other error here: 2083 */ 2084 errno = wait_errno; 2085 perror_msg_and_die("wait4(__WALL)"); 2086 } 2087 2088 if (pid == popen_pid) { 2089 if (!WIFSTOPPED(status)) 2090 popen_pid = 0; 2091 return true; 2092 } 2093 2094 if (debug_flag) 2095 print_debug_info(pid, status); 2096 2097 /* Look up 'pid' in our table. */ 2098 tcp = pid2tcb(pid); 2099 2100 if (!tcp) { 2101 tcp = maybe_allocate_tcb(pid, status); 2102 if (!tcp) 2103 return true; 2104 } 2105 2106 if (WIFSTOPPED(status)) 2107 get_regs(pid); 2108 else 2109 clear_regs(); 2110 2111 event = (unsigned int) status >> 16; 2112 2113 if (event == PTRACE_EVENT_EXEC) { 2114 /* 2115 * Under Linux, execve changes pid to thread leader's pid, 2116 * and we see this changed pid on EVENT_EXEC and later, 2117 * execve sysexit. Leader "disappears" without exit 2118 * notification. Let user know that, drop leader's tcb, 2119 * and fix up pid in execve thread's tcb. 2120 * Effectively, execve thread's tcb replaces leader's tcb. 2121 * 2122 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED 2123 * on exit syscall) in multithreaded programs exactly 2124 * in order to handle this case. 2125 * 2126 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0. 2127 * On 2.6 and earlier, it can return garbage. 2128 */ 2129 if (os_release >= KERNEL_VERSION(3,0,0)) 2130 tcp = maybe_switch_tcbs(tcp, pid); 2131 2132 if (detach_on_execve && !skip_one_b_execve) { 2133 detach(tcp); /* do "-b execve" thingy */ 2134 return true; 2135 } 2136 skip_one_b_execve = 0; 2137 } 2138 2139 /* Set current output file */ 2140 current_tcp = tcp; 2141 2142 if (cflag) { 2143 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime); 2144 tcp->stime = ru.ru_stime; 2145 } 2146 2147 if (WIFSIGNALED(status)) { 2148 print_signalled(tcp, pid, status); 2149 droptcb(tcp); 2150 return true; 2151 } 2152 2153 if (WIFEXITED(status)) { 2154 print_exited(tcp, pid, status); 2155 droptcb(tcp); 2156 return true; 2157 } 2158 2159 if (!WIFSTOPPED(status)) { 2160 /* 2161 * Neither signalled, exited or stopped. 2162 * How could that be? 2163 */ 2164 error_msg("pid %u not stopped!", pid); 2165 droptcb(tcp); 2166 return true; 2167 } 2168 2169 /* Is this the very first time we see this tracee stopped? */ 2170 if (tcp->flags & TCB_STARTUP) { 2171 startup_tcb(tcp); 2172 if (get_scno(tcp) == 1) 2173 tcp->s_prev_ent = tcp->s_ent; 2174 } 2175 2176 sig = WSTOPSIG(status); 2177 2178 if (event != 0) { 2179 /* Ptrace event */ 2180#if USE_SEIZE 2181 if (event == PTRACE_EVENT_STOP) { 2182 /* 2183 * PTRACE_INTERRUPT-stop or group-stop. 2184 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here. 2185 */ 2186 switch (sig) { 2187 case SIGSTOP: 2188 case SIGTSTP: 2189 case SIGTTIN: 2190 case SIGTTOU: 2191 stopped = true; 2192 goto show_stopsig; 2193 } 2194 } 2195#endif 2196 goto restart_tracee_with_sig_0; 2197 } 2198 2199 /* 2200 * Is this post-attach SIGSTOP? 2201 * Interestingly, the process may stop 2202 * with STOPSIG equal to some other signal 2203 * than SIGSTOP if we happend to attach 2204 * just before the process takes a signal. 2205 */ 2206 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) { 2207 if (debug_flag) 2208 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid); 2209 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP; 2210 goto restart_tracee_with_sig_0; 2211 } 2212 2213 if (sig != syscall_trap_sig) { 2214 siginfo_t si; 2215 2216 /* 2217 * True if tracee is stopped by signal 2218 * (as opposed to "tracee received signal"). 2219 * TODO: shouldn't we check for errno == EINVAL too? 2220 * We can get ESRCH instead, you know... 2221 */ 2222 stopped = ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0; 2223#if USE_SEIZE 2224show_stopsig: 2225#endif 2226 print_stopped(tcp, stopped ? NULL : &si, sig); 2227 2228 if (!stopped) 2229 /* It's signal-delivery-stop. Inject the signal */ 2230 goto restart_tracee; 2231 2232 /* It's group-stop */ 2233 if (use_seize) { 2234 /* 2235 * This ends ptrace-stop, but does *not* end group-stop. 2236 * This makes stopping signals work properly on straced process 2237 * (that is, process really stops. It used to continue to run). 2238 */ 2239 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) { 2240 /* Note: ptrace_restart emitted error message */ 2241 exit_code = 1; 2242 return false; 2243 } 2244 return true; 2245 } 2246 /* We don't have PTRACE_LISTEN support... */ 2247 goto restart_tracee; 2248 } 2249 2250 /* We handled quick cases, we are permitted to interrupt now. */ 2251 if (interrupted) 2252 return false; 2253 2254 /* 2255 * This should be syscall entry or exit. 2256 * Handle it. 2257 */ 2258 if (trace_syscall(tcp) < 0) { 2259 /* 2260 * ptrace() failed in trace_syscall(). 2261 * Likely a result of process disappearing mid-flight. 2262 * Observed case: exit_group() or SIGKILL terminating 2263 * all processes in thread group. 2264 * We assume that ptrace error was caused by process death. 2265 * We used to detach(tcp) here, but since we no longer 2266 * implement "detach before death" policy/hack, 2267 * we can let this process to report its death to us 2268 * normally, via WIFEXITED or WIFSIGNALED wait status. 2269 */ 2270 return true; 2271 } 2272 2273restart_tracee_with_sig_0: 2274 sig = 0; 2275 2276restart_tracee: 2277 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) { 2278 /* Note: ptrace_restart emitted error message */ 2279 exit_code = 1; 2280 return false; 2281 } 2282 2283 return true; 2284} 2285 2286int 2287main(int argc, char *argv[]) 2288{ 2289 init(argc, argv); 2290 2291 while (trace()) 2292 ; 2293 2294 cleanup(); 2295 fflush(NULL); 2296 if (shared_log != stderr) 2297 fclose(shared_log); 2298 if (popen_pid) { 2299 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR) 2300 ; 2301 } 2302 if (exit_code > 0xff) { 2303 /* Avoid potential core file clobbering. */ 2304 struct_rlimit rlim = {0, 0}; 2305 set_rlimit(RLIMIT_CORE, &rlim); 2306 2307 /* Child was killed by a signal, mimic that. */ 2308 exit_code &= 0xff; 2309 signal(exit_code, SIG_DFL); 2310 raise(exit_code); 2311 /* Paranoia - what if this signal is not fatal? 2312 Exit with 128 + signo then. */ 2313 exit_code += 128; 2314 } 2315 2316 return exit_code; 2317} 2318