1 /* $NetBSD: rm.c,v 1.54 2021/09/10 22:11:03 rillig Exp $ */
2
3 /*-
4 * Copyright (c) 1990, 1993, 1994, 2003
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #ifndef lint
34 __COPYRIGHT("@(#) Copyright (c) 1990, 1993, 1994\
35 The Regents of the University of California. All rights reserved.");
36 #endif /* not lint */
37
38 #ifndef lint
39 #if 0
40 static char sccsid[] = "@(#)rm.c 8.8 (Berkeley) 4/27/95";
41 #else
42 __RCSID("$NetBSD: rm.c,v 1.54 2021/09/10 22:11:03 rillig Exp $");
43 #endif
44 #endif /* not lint */
45
46 #include <sys/param.h>
47 #include <sys/stat.h>
48 #include <sys/types.h>
49
50 #include <err.h>
51 #include <errno.h>
52 #include <fcntl.h>
53 #include <fts.h>
54 #include <grp.h>
55 #include <locale.h>
56 #include <pwd.h>
57 #include <signal.h>
58 #include <stdio.h>
59 #include <stdlib.h>
60 #include <string.h>
61 #include <unistd.h>
62
63 static int dflag, eval, fflag, iflag, Pflag, stdin_ok, vflag, Wflag;
64 static int xflag;
65 static sig_atomic_t pinfo;
66
67 static int check(char *, char *, struct stat *);
68 static void checkdot(char **);
69 static void progress(int);
70 static void rm_file(char **);
71 static int rm_overwrite(char *, struct stat *);
72 static void rm_tree(char **);
73 __dead static void usage(void);
74
75 /*
76 * For the sake of the `-f' flag, check whether an error number indicates the
77 * failure of an operation due to an non-existent file, either per se (ENOENT)
78 * or because its filename argument was illegal (ENAMETOOLONG, ENOTDIR).
79 */
80 #define NONEXISTENT(x) \
81 ((x) == ENOENT || (x) == ENAMETOOLONG || (x) == ENOTDIR)
82
83 /*
84 * rm --
85 * This rm is different from historic rm's, but is expected to match
86 * POSIX 1003.2 behavior. The most visible difference is that -f
87 * has two specific effects now, ignore non-existent files and force
88 * file removal.
89 */
90 int
main(int argc,char * argv[])91 main(int argc, char *argv[])
92 {
93 int ch, rflag;
94
95 setprogname(argv[0]);
96 (void)setlocale(LC_ALL, "");
97
98 Pflag = rflag = xflag = 0;
99 while ((ch = getopt(argc, argv, "dfiPRrvWx")) != -1)
100 switch (ch) {
101 case 'd':
102 dflag = 1;
103 break;
104 case 'f':
105 fflag = 1;
106 iflag = 0;
107 break;
108 case 'i':
109 fflag = 0;
110 iflag = 1;
111 break;
112 case 'P':
113 Pflag = 1;
114 break;
115 case 'R':
116 case 'r': /* Compatibility. */
117 rflag = 1;
118 break;
119 case 'v':
120 vflag = 1;
121 break;
122 case 'x':
123 xflag = 1;
124 break;
125 case 'W':
126 Wflag = 1;
127 break;
128 case '?':
129 default:
130 usage();
131 }
132 argc -= optind;
133 argv += optind;
134
135 if (argc < 1) {
136 if (fflag)
137 return 0;
138 usage();
139 }
140
141 (void)signal(SIGINFO, progress);
142
143 checkdot(argv);
144
145 if (*argv) {
146 stdin_ok = isatty(STDIN_FILENO);
147
148 if (rflag)
149 rm_tree(argv);
150 else
151 rm_file(argv);
152 }
153
154 exit(eval);
155 /* NOTREACHED */
156 }
157
158 static void
rm_tree(char ** argv)159 rm_tree(char **argv)
160 {
161 FTS *fts;
162 FTSENT *p;
163 int flags, needstat, rval;
164
165 /*
166 * Remove a file hierarchy. If forcing removal (-f), or interactive
167 * (-i) or can't ask anyway (stdin_ok), don't stat the file.
168 */
169 needstat = !fflag && !iflag && stdin_ok;
170
171 /*
172 * If the -i option is specified, the user can skip on the pre-order
173 * visit. The fts_number field flags skipped directories.
174 */
175 #define SKIPPED 1
176
177 flags = FTS_PHYSICAL;
178 if (!needstat)
179 flags |= FTS_NOSTAT;
180 if (Wflag)
181 flags |= FTS_WHITEOUT;
182 if (xflag)
183 flags |= FTS_XDEV;
184 if ((fts = fts_open(argv, flags, NULL)) == NULL)
185 err(1, "fts_open failed");
186 while ((p = fts_read(fts)) != NULL) {
187
188 switch (p->fts_info) {
189 case FTS_DNR:
190 if (!fflag || p->fts_errno != ENOENT) {
191 warnx("%s: %s", p->fts_path,
192 strerror(p->fts_errno));
193 eval = 1;
194 }
195 continue;
196 case FTS_ERR:
197 errx(EXIT_FAILURE, "%s: %s", p->fts_path,
198 strerror(p->fts_errno));
199 /* NOTREACHED */
200 case FTS_NS:
201 /*
202 * FTS_NS: assume that if can't stat the file, it
203 * can't be unlinked.
204 */
205 if (fflag && NONEXISTENT(p->fts_errno))
206 continue;
207 if (needstat) {
208 warnx("%s: %s", p->fts_path,
209 strerror(p->fts_errno));
210 eval = 1;
211 continue;
212 }
213 break;
214 case FTS_D:
215 /* Pre-order: give user chance to skip. */
216 if (!fflag && !check(p->fts_path, p->fts_accpath,
217 p->fts_statp)) {
218 (void)fts_set(fts, p, FTS_SKIP);
219 p->fts_number = SKIPPED;
220 }
221 continue;
222 case FTS_DP:
223 /* Post-order: see if user skipped. */
224 if (p->fts_number == SKIPPED)
225 continue;
226 break;
227 default:
228 if (!fflag &&
229 !check(p->fts_path, p->fts_accpath, p->fts_statp))
230 continue;
231 }
232
233 rval = 0;
234 /*
235 * If we can't read or search the directory, may still be
236 * able to remove it. Don't print out the un{read,search}able
237 * message unless the remove fails.
238 */
239 switch (p->fts_info) {
240 case FTS_DP:
241 case FTS_DNR:
242 rval = rmdir(p->fts_accpath);
243 if (rval != 0 && fflag && errno == ENOENT)
244 continue;
245 break;
246
247 case FTS_W:
248 rval = undelete(p->fts_accpath);
249 if (rval != 0 && fflag && errno == ENOENT)
250 continue;
251 break;
252
253 default:
254 if (Pflag) {
255 if (rm_overwrite(p->fts_accpath, NULL))
256 continue;
257 }
258 rval = unlink(p->fts_accpath);
259 if (rval != 0 && fflag && NONEXISTENT(errno))
260 continue;
261 break;
262 }
263 if (rval != 0) {
264 warn("%s", p->fts_path);
265 eval = 1;
266 } else if (vflag || pinfo) {
267 pinfo = 0;
268 (void)printf("%s\n", p->fts_path);
269 }
270 }
271 if (errno)
272 err(1, "fts_read");
273 fts_close(fts);
274 }
275
276 static void
rm_file(char ** argv)277 rm_file(char **argv)
278 {
279 struct stat sb;
280 int rval;
281 char *f;
282
283 /*
284 * Remove a file. POSIX 1003.2 states that, by default, attempting
285 * to remove a directory is an error, so must always stat the file.
286 */
287 while ((f = *argv++) != NULL) {
288 /* Assume if can't stat the file, can't unlink it. */
289 if (lstat(f, &sb)) {
290 if (Wflag) {
291 sb.st_mode = S_IFWHT|S_IWUSR|S_IRUSR;
292 } else {
293 if (!fflag || !NONEXISTENT(errno)) {
294 warn("%s", f);
295 eval = 1;
296 }
297 continue;
298 }
299 } else if (Wflag) {
300 warnx("%s: %s", f, strerror(EEXIST));
301 eval = 1;
302 continue;
303 }
304
305 if (S_ISDIR(sb.st_mode) && !dflag) {
306 warnx("%s: is a directory", f);
307 eval = 1;
308 continue;
309 }
310 if (!fflag && !S_ISWHT(sb.st_mode) && !check(f, f, &sb))
311 continue;
312 if (S_ISWHT(sb.st_mode))
313 rval = undelete(f);
314 else if (S_ISDIR(sb.st_mode))
315 rval = rmdir(f);
316 else {
317 if (Pflag) {
318 if (rm_overwrite(f, &sb))
319 continue;
320 }
321 rval = unlink(f);
322 }
323 if (rval && (!fflag || !NONEXISTENT(errno))) {
324 warn("%s", f);
325 eval = 1;
326 }
327 if (vflag && rval == 0)
328 (void)printf("%s\n", f);
329 }
330 }
331
332 /*
333 * rm_overwrite --
334 * Overwrite the file 3 times with varying bit patterns.
335 *
336 * This is an expensive way to keep people from recovering files from your
337 * non-snapshotted FFS filesystems using fsdb(8). Really. No more. Only
338 * regular files are deleted, directories (and therefore names) will remain.
339 * Also, this assumes a fixed-block file system (like FFS, or a V7 or a
340 * System V file system). In a logging file system, you'll have to have
341 * kernel support.
342 *
343 * A note on standards: U.S. DoD 5220.22-M "National Industrial Security
344 * Program Operating Manual" ("NISPOM") is often cited as a reference
345 * for clearing and sanitizing magnetic media. In fact, a matrix of
346 * "clearing" and "sanitization" methods for various media was given in
347 * Chapter 8 of the original 1995 version of NISPOM. However, that
348 * matrix was *removed from the document* when Chapter 8 was rewritten
349 * in Change 2 to the document in 2001. Recently, the Defense Security
350 * Service has made a revised clearing and sanitization matrix available
351 * in Microsoft Word format on the DSS web site. The standardization
352 * status of this matrix is unclear. Furthermore, one must be very
353 * careful when referring to this matrix: it is intended for the "clearing"
354 * prior to reuse or "sanitization" prior to disposal of *entire media*,
355 * not individual files and the only non-physically-destructive method of
356 * "sanitization" that is permitted for magnetic disks of any kind is
357 * specifically noted to be prohibited for media that have contained
358 * Top Secret data.
359 *
360 * It is impossible to actually conform to the exact procedure given in
361 * the matrix if one is overwriting a file, not an entire disk, because
362 * the procedure requires examination and comparison of the disk's defect
363 * lists. Any program that claims to securely erase *files* while
364 * conforming to the standard, then, is not correct. We do as much of
365 * what the standard requires as can actually be done when erasing a
366 * file, rather than an entire disk; but that does not make us conformant.
367 *
368 * Furthermore, the presence of track caches, disk and controller write
369 * caches, and so forth make it extremely difficult to ensure that data
370 * have actually been written to the disk, particularly when one tries
371 * to repeatedly overwrite the same sectors in quick succession. We call
372 * fsync(), but controllers with nonvolatile cache, as well as IDE disks
373 * that just plain lie about the stable storage of data, will defeat this.
374 *
375 * Finally, widely respected research suggests that the given procedure
376 * is nowhere near sufficient to prevent the recovery of data using special
377 * forensic equipment and techniques that are well-known. This is
378 * presumably one reason that the matrix requires physical media destruction,
379 * rather than any technique of the sort attempted here, for secret data.
380 *
381 * Caveat Emptor.
382 *
383 * rm_overwrite will return 0 on success.
384 */
385
386 static int
rm_overwrite(char * file,struct stat * sbp)387 rm_overwrite(char *file, struct stat *sbp)
388 {
389 struct stat sb, sb2;
390 int fd, randint;
391 char randchar;
392
393 fd = -1;
394 if (sbp == NULL) {
395 if (lstat(file, &sb))
396 goto err;
397 sbp = &sb;
398 }
399 if (!S_ISREG(sbp->st_mode))
400 return 0;
401
402 /* flags to try to defeat hidden caching by forcing seeks */
403 if ((fd = open(file, O_RDWR|O_SYNC|O_RSYNC|O_NOFOLLOW, 0)) == -1)
404 goto err;
405
406 if (fstat(fd, &sb2)) {
407 goto err;
408 }
409
410 if (sb2.st_dev != sbp->st_dev || sb2.st_ino != sbp->st_ino ||
411 !S_ISREG(sb2.st_mode)) {
412 errno = EPERM;
413 goto err;
414 }
415
416 #define RAND_BYTES 1
417 #define THIS_BYTE 0
418
419 #define WRITE_PASS(mode, byte) do { \
420 off_t len; \
421 size_t wlen, i; \
422 char buf[8 * 1024]; \
423 \
424 if (fsync(fd) || lseek(fd, (off_t)0, SEEK_SET)) \
425 goto err; \
426 \
427 if (mode == THIS_BYTE) \
428 memset(buf, byte, sizeof(buf)); \
429 for (len = sbp->st_size; len > 0; len -= wlen) { \
430 if (mode == RAND_BYTES) { \
431 for (i = 0; i < sizeof(buf); \
432 i+= sizeof(u_int32_t)) \
433 *(int *)(buf + i) = arc4random(); \
434 } \
435 wlen = len < (off_t)sizeof(buf) ? (size_t)len : sizeof(buf); \
436 if ((size_t)write(fd, buf, wlen) != wlen) \
437 goto err; \
438 } \
439 sync(); /* another poke at hidden caches */ \
440 } while (0)
441
442 #define READ_PASS(byte) do { \
443 off_t len; \
444 size_t rlen; \
445 char pattern[8 * 1024]; \
446 char buf[8 * 1024]; \
447 \
448 if (fsync(fd) || lseek(fd, (off_t)0, SEEK_SET)) \
449 goto err; \
450 \
451 memset(pattern, byte, sizeof(pattern)); \
452 for(len = sbp->st_size; len > 0; len -= rlen) { \
453 rlen = len < (off_t)sizeof(buf) ? (size_t)len : sizeof(buf); \
454 if((size_t)read(fd, buf, rlen) != rlen) \
455 goto err; \
456 if(memcmp(buf, pattern, rlen)) \
457 goto err; \
458 } \
459 sync(); /* another poke at hidden caches */ \
460 } while (0)
461
462 /*
463 * DSS sanitization matrix "clear" for magnetic disks:
464 * option 'c' "Overwrite all addressable locations with a single
465 * character."
466 */
467 randint = arc4random();
468 randchar = *(char *)&randint;
469 WRITE_PASS(THIS_BYTE, randchar);
470
471 /*
472 * DSS sanitization matrix "sanitize" for magnetic disks:
473 * option 'd', sub 2 "Overwrite all addressable locations with a
474 * character, then its complement. Verify "complement" character
475 * was written successfully to all addressable locations, then
476 * overwrite all addressable locations with random characters; or
477 * verify third overwrite of random characters." The rest of the
478 * text in d-sub-2 specifies requirements for overwriting spared
479 * sectors; we cannot conform to it when erasing only a file, thus
480 * we do not conform to the standard.
481 */
482
483 /* 1. "a character" */
484 WRITE_PASS(THIS_BYTE, 0xff);
485
486 /* 2. "its complement" */
487 WRITE_PASS(THIS_BYTE, 0x00);
488
489 /* 3. "Verify 'complement' character" */
490 READ_PASS(0x00);
491
492 /* 4. "overwrite all addressable locations with random characters" */
493
494 WRITE_PASS(RAND_BYTES, 0x00);
495
496 /*
497 * As the file might be huge, and we note that this revision of
498 * the matrix says "random characters", not "a random character"
499 * as the original did, we do not verify the random-character
500 * write; the "or" in the standard allows this.
501 */
502
503 if (close(fd) == -1) {
504 fd = -1;
505 goto err;
506 }
507
508 return 0;
509
510 err: eval = 1;
511 warn("%s", file);
512 if (fd != -1)
513 close(fd);
514 return 1;
515 }
516
517 static int
check(char * path,char * name,struct stat * sp)518 check(char *path, char *name, struct stat *sp)
519 {
520 int ch, first;
521 char modep[15];
522
523 /* Check -i first. */
524 if (iflag)
525 (void)fprintf(stderr, "remove '%s'? ", path);
526 else {
527 /*
528 * If it's not a symbolic link and it's unwritable and we're
529 * talking to a terminal, ask. Symbolic links are excluded
530 * because their permissions are meaningless. Check stdin_ok
531 * first because we may not have stat'ed the file.
532 */
533 if (!stdin_ok || S_ISLNK(sp->st_mode) ||
534 !(access(name, W_OK) && (errno != ETXTBSY)))
535 return (1);
536 strmode(sp->st_mode, modep);
537 if (Pflag) {
538 warnx(
539 "%s: -P was specified but file could not"
540 " be overwritten", path);
541 return 0;
542 }
543 (void)fprintf(stderr, "override %s%s%s:%s for '%s'? ",
544 modep + 1, modep[9] == ' ' ? "" : " ",
545 user_from_uid(sp->st_uid, 0),
546 group_from_gid(sp->st_gid, 0), path);
547 }
548 (void)fflush(stderr);
549
550 first = ch = getchar();
551 while (ch != '\n' && ch != EOF)
552 ch = getchar();
553 return (first == 'y' || first == 'Y');
554 }
555
556 /*
557 * POSIX.2 requires that if "." or ".." are specified as the basename
558 * portion of an operand, a diagnostic message be written to standard
559 * error and nothing more be done with such operands.
560 *
561 * Since POSIX.2 defines basename as the final portion of a path after
562 * trailing slashes have been removed, we'll remove them here.
563 */
564 #define ISDOT(a) ((a)[0] == '.' && (!(a)[1] || ((a)[1] == '.' && !(a)[2])))
565 static void
checkdot(char ** argv)566 checkdot(char **argv)
567 {
568 char *p, **save, **t;
569 int complained;
570
571 complained = 0;
572 for (t = argv; *t;) {
573 /* strip trailing slashes */
574 p = strrchr(*t, '\0');
575 while (--p > *t && *p == '/')
576 *p = '\0';
577
578 /* extract basename */
579 if ((p = strrchr(*t, '/')) != NULL)
580 ++p;
581 else
582 p = *t;
583
584 if (ISDOT(p)) {
585 if (!complained++)
586 warnx("\".\" and \"..\" may not be removed");
587 eval = 1;
588 for (save = t; (t[0] = t[1]) != NULL; ++t)
589 continue;
590 t = save;
591 } else
592 ++t;
593 }
594 }
595
596 static void
usage(void)597 usage(void)
598 {
599
600 (void)fprintf(stderr, "usage: %s [-f|-i] [-dPRrvWx] file ...\n",
601 getprogname());
602 exit(1);
603 /* NOTREACHED */
604 }
605
606 static void
progress(int sig __unused)607 progress(int sig __unused)
608 {
609
610 pinfo++;
611 }
612