1 /* $NetBSD: rm.c,v 1.49 2009/02/14 08:05:04 lukem 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 1.49 2009/02/14 08:05:04 lukem 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 <stdio.h> 58 #include <stdlib.h> 59 #include <string.h> 60 #include <unistd.h> 61 62 int dflag, eval, fflag, iflag, Pflag, stdin_ok, vflag, Wflag; 63 64 int check(char *, char *, struct stat *); 65 void checkdot(char **); 66 void rm_file(char **); 67 int rm_overwrite(char *, struct stat *); 68 void rm_tree(char **); 69 void usage(void); 70 int main(int, char *[]); 71 72 /* 73 * For the sake of the `-f' flag, check whether an error number indicates the 74 * failure of an operation due to an non-existent file, either per se (ENOENT) 75 * or because its filename argument was illegal (ENAMETOOLONG, ENOTDIR). 76 */ 77 #define NONEXISTENT(x) \ 78 ((x) == ENOENT || (x) == ENAMETOOLONG || (x) == ENOTDIR) 79 80 /* 81 * rm -- 82 * This rm is different from historic rm's, but is expected to match 83 * POSIX 1003.2 behavior. The most visible difference is that -f 84 * has two specific effects now, ignore non-existent files and force 85 * file removal. 86 */ 87 int 88 main(int argc, char *argv[]) 89 { 90 int ch, rflag; 91 92 setprogname(argv[0]); 93 (void)setlocale(LC_ALL, ""); 94 95 Pflag = rflag = 0; 96 while ((ch = getopt(argc, argv, "dfiPRrvW")) != -1) 97 switch (ch) { 98 case 'd': 99 dflag = 1; 100 break; 101 case 'f': 102 fflag = 1; 103 iflag = 0; 104 break; 105 case 'i': 106 fflag = 0; 107 iflag = 1; 108 break; 109 case 'P': 110 Pflag = 1; 111 break; 112 case 'R': 113 case 'r': /* Compatibility. */ 114 rflag = 1; 115 break; 116 case 'v': 117 vflag = 1; 118 break; 119 case 'W': 120 Wflag = 1; 121 break; 122 case '?': 123 default: 124 usage(); 125 } 126 argc -= optind; 127 argv += optind; 128 129 if (argc < 1) { 130 if (fflag) 131 return 0; 132 usage(); 133 } 134 135 checkdot(argv); 136 137 if (*argv) { 138 stdin_ok = isatty(STDIN_FILENO); 139 140 if (rflag) 141 rm_tree(argv); 142 else 143 rm_file(argv); 144 } 145 146 exit(eval); 147 /* NOTREACHED */ 148 } 149 150 void 151 rm_tree(char **argv) 152 { 153 FTS *fts; 154 FTSENT *p; 155 int flags, needstat, rval; 156 157 /* 158 * Remove a file hierarchy. If forcing removal (-f), or interactive 159 * (-i) or can't ask anyway (stdin_ok), don't stat the file. 160 */ 161 needstat = !fflag && !iflag && stdin_ok; 162 163 /* 164 * If the -i option is specified, the user can skip on the pre-order 165 * visit. The fts_number field flags skipped directories. 166 */ 167 #define SKIPPED 1 168 169 flags = FTS_PHYSICAL; 170 if (!needstat) 171 flags |= FTS_NOSTAT; 172 if (Wflag) 173 flags |= FTS_WHITEOUT; 174 if ((fts = fts_open(argv, flags, NULL)) == NULL) 175 err(1, "fts_open failed"); 176 while ((p = fts_read(fts)) != NULL) { 177 178 switch (p->fts_info) { 179 case FTS_DNR: 180 if (!fflag || p->fts_errno != ENOENT) { 181 warnx("%s: %s", p->fts_path, 182 strerror(p->fts_errno)); 183 eval = 1; 184 } 185 continue; 186 case FTS_ERR: 187 errx(EXIT_FAILURE, "%s: %s", p->fts_path, 188 strerror(p->fts_errno)); 189 /* NOTREACHED */ 190 case FTS_NS: 191 /* 192 * FTS_NS: assume that if can't stat the file, it 193 * can't be unlinked. 194 */ 195 if (fflag && NONEXISTENT(p->fts_errno)) 196 continue; 197 if (needstat) { 198 warnx("%s: %s", p->fts_path, 199 strerror(p->fts_errno)); 200 eval = 1; 201 continue; 202 } 203 break; 204 case FTS_D: 205 /* Pre-order: give user chance to skip. */ 206 if (!fflag && !check(p->fts_path, p->fts_accpath, 207 p->fts_statp)) { 208 (void)fts_set(fts, p, FTS_SKIP); 209 p->fts_number = SKIPPED; 210 } 211 continue; 212 case FTS_DP: 213 /* Post-order: see if user skipped. */ 214 if (p->fts_number == SKIPPED) 215 continue; 216 break; 217 default: 218 if (!fflag && 219 !check(p->fts_path, p->fts_accpath, p->fts_statp)) 220 continue; 221 } 222 223 rval = 0; 224 /* 225 * If we can't read or search the directory, may still be 226 * able to remove it. Don't print out the un{read,search}able 227 * message unless the remove fails. 228 */ 229 switch (p->fts_info) { 230 case FTS_DP: 231 case FTS_DNR: 232 rval = rmdir(p->fts_accpath); 233 if (rval != 0 && fflag && errno == ENOENT) 234 continue; 235 break; 236 237 case FTS_W: 238 rval = undelete(p->fts_accpath); 239 if (rval != 0 && fflag && errno == ENOENT) 240 continue; 241 break; 242 243 default: 244 if (Pflag) { 245 if (rm_overwrite(p->fts_accpath, NULL)) 246 continue; 247 } 248 rval = unlink(p->fts_accpath); 249 if (rval != 0 && fflag && NONEXISTENT(errno)) 250 continue; 251 break; 252 } 253 if (rval != 0) { 254 warn("%s", p->fts_path); 255 eval = 1; 256 } else if (vflag) 257 (void)printf("%s\n", p->fts_path); 258 } 259 if (errno) 260 err(1, "fts_read"); 261 fts_close(fts); 262 } 263 264 void 265 rm_file(char **argv) 266 { 267 struct stat sb; 268 int rval; 269 char *f; 270 271 /* 272 * Remove a file. POSIX 1003.2 states that, by default, attempting 273 * to remove a directory is an error, so must always stat the file. 274 */ 275 while ((f = *argv++) != NULL) { 276 /* Assume if can't stat the file, can't unlink it. */ 277 if (lstat(f, &sb)) { 278 if (Wflag) { 279 sb.st_mode = S_IFWHT|S_IWUSR|S_IRUSR; 280 } else { 281 if (!fflag || !NONEXISTENT(errno)) { 282 warn("%s", f); 283 eval = 1; 284 } 285 continue; 286 } 287 } else if (Wflag) { 288 warnx("%s: %s", f, strerror(EEXIST)); 289 eval = 1; 290 continue; 291 } 292 293 if (S_ISDIR(sb.st_mode) && !dflag) { 294 warnx("%s: is a directory", f); 295 eval = 1; 296 continue; 297 } 298 if (!fflag && !S_ISWHT(sb.st_mode) && !check(f, f, &sb)) 299 continue; 300 if (S_ISWHT(sb.st_mode)) 301 rval = undelete(f); 302 else if (S_ISDIR(sb.st_mode)) 303 rval = rmdir(f); 304 else { 305 if (Pflag) { 306 if (rm_overwrite(f, &sb)) 307 continue; 308 } 309 rval = unlink(f); 310 } 311 if (rval && (!fflag || !NONEXISTENT(errno))) { 312 warn("%s", f); 313 eval = 1; 314 } 315 if (vflag && rval == 0) 316 (void)printf("%s\n", f); 317 } 318 } 319 320 /* 321 * rm_overwrite -- 322 * Overwrite the file 3 times with varying bit patterns. 323 * 324 * This is an expensive way to keep people from recovering files from your 325 * non-snapshotted FFS filesystems using fsdb(8). Really. No more. Only 326 * regular files are deleted, directories (and therefore names) will remain. 327 * Also, this assumes a fixed-block file system (like FFS, or a V7 or a 328 * System V file system). In a logging file system, you'll have to have 329 * kernel support. 330 * 331 * A note on standards: U.S. DoD 5220.22-M "National Industrial Security 332 * Program Operating Manual" ("NISPOM") is often cited as a reference 333 * for clearing and sanitizing magnetic media. In fact, a matrix of 334 * "clearing" and "sanitization" methods for various media was given in 335 * Chapter 8 of the original 1995 version of NISPOM. However, that 336 * matrix was *removed from the document* when Chapter 8 was rewritten 337 * in Change 2 to the document in 2001. Recently, the Defense Security 338 * Service has made a revised clearing and sanitization matrix available 339 * in Microsoft Word format on the DSS web site. The standardization 340 * status of this matrix is unclear. Furthermore, one must be very 341 * careful when referring to this matrix: it is intended for the "clearing" 342 * prior to reuse or "sanitization" prior to disposal of *entire media*, 343 * not individual files and the only non-physically-destructive method of 344 * "sanitization" that is permitted for magnetic disks of any kind is 345 * specifically noted to be prohibited for media that have contained 346 * Top Secret data. 347 * 348 * It is impossible to actually conform to the exact procedure given in 349 * the matrix if one is overwriting a file, not an entire disk, because 350 * the procedure requires examination and comparison of the disk's defect 351 * lists. Any program that claims to securely erase *files* while 352 * conforming to the standard, then, is not correct. We do as much of 353 * what the standard requires as can actually be done when erasing a 354 * file, rather than an entire disk; but that does not make us conformant. 355 * 356 * Furthermore, the presence of track caches, disk and controller write 357 * caches, and so forth make it extremely difficult to ensure that data 358 * have actually been written to the disk, particularly when one tries 359 * to repeatedly overwrite the same sectors in quick succession. We call 360 * fsync(), but controllers with nonvolatile cache, as well as IDE disks 361 * that just plain lie about the stable storage of data, will defeat this. 362 * 363 * Finally, widely respected research suggests that the given procedure 364 * is nowhere near sufficient to prevent the recovery of data using special 365 * forensic equipment and techniques that are well-known. This is 366 * presumably one reason that the matrix requires physical media destruction, 367 * rather than any technique of the sort attempted here, for secret data. 368 * 369 * Caveat Emptor. 370 * 371 * rm_overwrite will return 0 on success. 372 */ 373 374 int 375 rm_overwrite(char *file, struct stat *sbp) 376 { 377 struct stat sb; 378 int fd, randint; 379 char randchar; 380 381 fd = -1; 382 if (sbp == NULL) { 383 if (lstat(file, &sb)) 384 goto err; 385 sbp = &sb; 386 } 387 if (!S_ISREG(sbp->st_mode)) 388 return 0; 389 390 /* flags to try to defeat hidden caching by forcing seeks */ 391 if ((fd = open(file, O_RDWR|O_SYNC|O_RSYNC, 0)) == -1) 392 goto err; 393 394 #define RAND_BYTES 1 395 #define THIS_BYTE 0 396 397 #define WRITE_PASS(mode, byte) do { \ 398 off_t len; \ 399 size_t wlen, i; \ 400 char buf[8 * 1024]; \ 401 \ 402 if (fsync(fd) || lseek(fd, (off_t)0, SEEK_SET)) \ 403 goto err; \ 404 \ 405 if (mode == THIS_BYTE) \ 406 memset(buf, byte, sizeof(buf)); \ 407 for (len = sbp->st_size; len > 0; len -= wlen) { \ 408 if (mode == RAND_BYTES) { \ 409 for (i = 0; i < sizeof(buf); \ 410 i+= sizeof(u_int32_t)) \ 411 *(int *)(buf + i) = arc4random(); \ 412 } \ 413 wlen = len < (off_t)sizeof(buf) ? (size_t)len : sizeof(buf); \ 414 if ((size_t)write(fd, buf, wlen) != wlen) \ 415 goto err; \ 416 } \ 417 sync(); /* another poke at hidden caches */ \ 418 } while (/* CONSTCOND */ 0) 419 420 #define READ_PASS(byte) do { \ 421 off_t len; \ 422 size_t rlen; \ 423 char pattern[8 * 1024]; \ 424 char buf[8 * 1024]; \ 425 \ 426 if (fsync(fd) || lseek(fd, (off_t)0, SEEK_SET)) \ 427 goto err; \ 428 \ 429 memset(pattern, byte, sizeof(pattern)); \ 430 for(len = sbp->st_size; len > 0; len -= rlen) { \ 431 rlen = len < (off_t)sizeof(buf) ? (size_t)len : sizeof(buf); \ 432 if((size_t)read(fd, buf, rlen) != rlen) \ 433 goto err; \ 434 if(memcmp(buf, pattern, rlen)) \ 435 goto err; \ 436 } \ 437 sync(); /* another poke at hidden caches */ \ 438 } while (/* CONSTCOND */ 0) 439 440 /* 441 * DSS sanitization matrix "clear" for magnetic disks: 442 * option 'c' "Overwrite all addressable locations with a single 443 * character." 444 */ 445 randint = arc4random(); 446 randchar = *(char *)&randint; 447 WRITE_PASS(THIS_BYTE, randchar); 448 449 /* 450 * DSS sanitization matrix "sanitize" for magnetic disks: 451 * option 'd', sub 2 "Overwrite all addressable locations with a 452 * character, then its complement. Verify "complement" character 453 * was written successfully to all addressable locations, then 454 * overwrite all addressable locations with random characters; or 455 * verify third overwrite of random characters." The rest of the 456 * text in d-sub-2 specifies requirements for overwriting spared 457 * sectors; we cannot conform to it when erasing only a file, thus 458 * we do not conform to the standard. 459 */ 460 461 /* 1. "a character" */ 462 WRITE_PASS(THIS_BYTE, 0xff); 463 464 /* 2. "its complement" */ 465 WRITE_PASS(THIS_BYTE, 0x00); 466 467 /* 3. "Verify 'complement' character" */ 468 READ_PASS(0x00); 469 470 /* 4. "overwrite all addressable locations with random characters" */ 471 472 WRITE_PASS(RAND_BYTES, 0x00); 473 474 /* 475 * As the file might be huge, and we note that this revision of 476 * the matrix says "random characters", not "a random character" 477 * as the original did, we do not verify the random-character 478 * write; the "or" in the standard allows this. 479 */ 480 481 if (close(fd) == -1) { 482 fd = -1; 483 goto err; 484 } 485 486 return 0; 487 488 err: eval = 1; 489 warn("%s", file); 490 if (fd != -1) 491 close(fd); 492 return 1; 493 } 494 495 int 496 check(char *path, char *name, struct stat *sp) 497 { 498 int ch, first; 499 char modep[15]; 500 501 /* Check -i first. */ 502 if (iflag) 503 (void)fprintf(stderr, "remove '%s'? ", path); 504 else { 505 /* 506 * If it's not a symbolic link and it's unwritable and we're 507 * talking to a terminal, ask. Symbolic links are excluded 508 * because their permissions are meaningless. Check stdin_ok 509 * first because we may not have stat'ed the file. 510 */ 511 if (!stdin_ok || S_ISLNK(sp->st_mode) || 512 !(access(name, W_OK) && (errno != ETXTBSY))) 513 return (1); 514 strmode(sp->st_mode, modep); 515 if (Pflag) { 516 warnx( 517 "%s: -P was specified but file could not" 518 " be overwritten", path); 519 return 0; 520 } 521 (void)fprintf(stderr, "override %s%s%s:%s for '%s'? ", 522 modep + 1, modep[9] == ' ' ? "" : " ", 523 user_from_uid(sp->st_uid, 0), 524 group_from_gid(sp->st_gid, 0), path); 525 } 526 (void)fflush(stderr); 527 528 first = ch = getchar(); 529 while (ch != '\n' && ch != EOF) 530 ch = getchar(); 531 return (first == 'y' || first == 'Y'); 532 } 533 534 /* 535 * POSIX.2 requires that if "." or ".." are specified as the basename 536 * portion of an operand, a diagnostic message be written to standard 537 * error and nothing more be done with such operands. 538 * 539 * Since POSIX.2 defines basename as the final portion of a path after 540 * trailing slashes have been removed, we'll remove them here. 541 */ 542 #define ISDOT(a) ((a)[0] == '.' && (!(a)[1] || ((a)[1] == '.' && !(a)[2]))) 543 void 544 checkdot(char **argv) 545 { 546 char *p, **save, **t; 547 int complained; 548 549 complained = 0; 550 for (t = argv; *t;) { 551 /* strip trailing slashes */ 552 p = strrchr(*t, '\0'); 553 while (--p > *t && *p == '/') 554 *p = '\0'; 555 556 /* extract basename */ 557 if ((p = strrchr(*t, '/')) != NULL) 558 ++p; 559 else 560 p = *t; 561 562 if (ISDOT(p)) { 563 if (!complained++) 564 warnx("\".\" and \"..\" may not be removed"); 565 eval = 1; 566 for (save = t; (t[0] = t[1]) != NULL; ++t) 567 continue; 568 t = save; 569 } else 570 ++t; 571 } 572 } 573 574 void 575 usage(void) 576 { 577 578 (void)fprintf(stderr, "usage: %s [-f|-i] [-dPRrvW] file ...\n", 579 getprogname()); 580 exit(1); 581 /* NOTREACHED */ 582 } 583