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: */
49 extern char **environ;
50 extern int optind;
51 extern char *optarg;
52
53 #ifdef USE_LIBUNWIND
54 /* if this is true do the stack trace for every system call */
55 bool 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
77 const unsigned int syscall_trap_sig = SIGTRAP | 0x80;
78
79 cflag_t cflag = CFLAG_NONE;
80 unsigned int followfork = 0;
81 unsigned int ptrace_setoptions = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC;
82 unsigned int xflag = 0;
83 bool debug_flag = 0;
84 bool Tflag = 0;
85 bool iflag = 0;
86 bool count_wallclock = 0;
87 unsigned int qflag = 0;
88 static unsigned int tflag = 0;
89 static bool rflag = 0;
90 static bool print_pid_pfx = 0;
91
92 /* -I n */
93 enum {
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 };
101 static 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 */
117 static bool daemonized_tracer = 0;
118
119 #if USE_SEIZE
120 static 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. */
128 bool not_failing_only = 0;
129
130 /* Show path associated with fd arguments */
131 unsigned int show_fd_path = 0;
132
133 static bool detach_on_execve = 0;
134 /* Are we "strace PROG" and need to skip detach on first execve? */
135 static bool skip_one_b_execve = 0;
136 /* Are we "strace PROG" and need to hide everything until execve? */
137 bool hide_log_until_execve = 0;
138
139 static int exit_code = 0;
140 static int strace_child = 0;
141 static int strace_tracer_pid = 0;
142
143 static char *username = NULL;
144 static uid_t run_uid;
145 static gid_t run_gid;
146
147 unsigned int max_strlen = DEFAULT_STRLEN;
148 static int acolumn = DEFAULT_ACOLUMN;
149 static char *acolumn_spaces;
150
151 static char *outfname = NULL;
152 /* If -ff, points to stderr. Else, it's our common output log */
153 static FILE *shared_log;
154
155 struct tcb *printing_tcp = NULL;
156 static struct tcb *current_tcp;
157
158 static struct tcb **tcbtab;
159 static unsigned int nprocs, tcbtabsize;
160 static const char *progname;
161
162 unsigned os_release; /* generated from uname()'s u.release */
163
164 static void detach(struct tcb *tcp);
165 static void cleanup(void);
166 static void interrupt(int sig);
167 static sigset_t empty_set, blocked_set;
168
169 #ifdef HAVE_SIG_ATOMIC_T
170 static volatile sig_atomic_t interrupted;
171 #else
172 static volatile int interrupted;
173 #endif
174
175 #ifndef HAVE_STRERROR
176
177 #if !HAVE_DECL_SYS_ERRLIST
178 extern int sys_nerr;
179 extern char *sys_errlist[];
180 #endif
181
182 const char *
strerror(int err_no)183 strerror(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
196 static void
usage(FILE * ofp,int exitval)197 usage(FILE *ofp, int exitval)
198 {
199 fprintf(ofp, "\
200 usage: 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
254 static void ATTRIBUTE_NORETURN
die(void)255 die(void)
256 {
257 if (strace_tracer_pid == getpid()) {
258 cflag = 0;
259 cleanup();
260 }
261 exit(1);
262 }
263
verror_msg(int err_no,const char * fmt,va_list p)264 static 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
error_msg(const char * fmt,...)295 void 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
error_msg_and_die(const char * fmt,...)303 void 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
perror_msg(const char * fmt,...)311 void 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
perror_msg_and_die(const char * fmt,...)319 void 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
die_out_of_memory(void)327 void 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
336 static void
error_opt_arg(int opt,const char * arg)337 error_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
343 static int
ptrace_attach_or_seize(int pid)344 ptrace_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 */
366 static int
ptrace_restart(int op,struct tcb * tcp,int sig)367 ptrace_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
407 static void
set_cloexec_flag(int fd)408 set_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
kill_save_errno(pid_t pid,int sig)429 static 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 */
441 static void
swap_uid(void)442 swap_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
473 static FILE *
strace_fopen(const char * path)474 strace_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
487 static 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 */
498 static FILE *
strace_popen(const char * command)499 strace_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
537 void
tprintf(const char * fmt,...)538 tprintf(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
558 void
tprints(const char * str)559 tprints(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
572 void
line_ended(void)573 line_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
585 void
printleader(struct tcb * tcp)586 printleader(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
648 void
tabto(void)649 tabto(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 */
659 static void
newoutf(struct tcb * tcp)660 newoutf(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
670 static void
expand_tcbtab(void)671 expand_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
689 static struct tcb *
alloctcb(int pid)690 alloctcb(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
721 static void
droptcb(struct tcb * tcp)722 droptcb(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 */
762 static void
detach(struct tcb * tcp)763 detach(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
923 static void
process_opt_p_list(char * opt)924 process_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
951 static void
startup_attach(void)952 startup_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 */
1092 struct exec_params {
1093 int fd_to_close;
1094 uid_t run_euid;
1095 gid_t run_egid;
1096 char **argv;
1097 char *pathname;
1098 };
1099 static struct exec_params params_for_tracee;
1100
1101 static void ATTRIBUTE_NOINLINE ATTRIBUTE_NORETURN
exec_or_die(void)1102 exec_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
1156 static void
startup_child(char ** argv)1157 startup_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
1329 static void
test_ptrace_seize(void)1330 test_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
1383 static unsigned
get_os_release(void)1384 get_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 */
1424 static void ATTRIBUTE_NOINLINE
init(int argc,char * argv[])1425 init(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
1769 static struct tcb *
pid2tcb(int pid)1770 pid2tcb(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
1786 static void
cleanup(void)1787 cleanup(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
1815 static void
interrupt(int sig)1816 interrupt(int sig)
1817 {
1818 interrupted = sig;
1819 }
1820
1821 static void
print_debug_info(const int pid,int status)1822 print_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
1868 static struct tcb *
maybe_allocate_tcb(const int pid,int status)1869 maybe_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
1902 static struct tcb *
maybe_switch_tcbs(struct tcb * tcp,const int pid)1903 maybe_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
1951 static void
print_signalled(struct tcb * tcp,const int pid,int status)1952 print_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
1975 static void
print_exited(struct tcb * tcp,const int pid,int status)1976 print_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
1991 static void
print_stopped(struct tcb * tcp,const siginfo_t * si,const unsigned int sig)1992 print_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
2009 static void
startup_tcb(struct tcb * tcp)2010 startup_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. */
2032 static bool
trace(void)2033 trace(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
2224 show_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
2273 restart_tracee_with_sig_0:
2274 sig = 0;
2275
2276 restart_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
2286 int
main(int argc,char * argv[])2287 main(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