1 /* $OpenBSD: file.c,v 1.54 2015/11/13 08:30:18 nicm Exp $ */ 2 3 /* 4 * Copyright (c) 2015 Nicholas Marriott <nicm@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER 15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING 16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 #include <sys/ioctl.h> 21 #include <sys/mman.h> 22 #include <sys/socket.h> 23 #include <sys/queue.h> 24 #include <sys/uio.h> 25 #include <sys/wait.h> 26 27 #include <errno.h> 28 #include <imsg.h> 29 #include <libgen.h> 30 #include <getopt.h> 31 #include <fcntl.h> 32 #include <pwd.h> 33 #include <stdlib.h> 34 #include <time.h> 35 #include <unistd.h> 36 #include <limits.h> 37 38 #include "file.h" 39 #include "magic.h" 40 #include "xmalloc.h" 41 42 struct input_msg 43 { 44 int idx; 45 46 struct stat sb; 47 int error; 48 49 char link_path[PATH_MAX]; 50 int link_error; 51 int link_target; 52 }; 53 54 struct input_ack 55 { 56 int idx; 57 }; 58 59 struct input_file 60 { 61 struct magic *m; 62 struct input_msg *msg; 63 64 const char *path; 65 int fd; 66 67 void *base; 68 size_t size; 69 int mapped; 70 char *result; 71 }; 72 73 extern char *__progname; 74 75 __dead void usage(void); 76 77 static void send_message(struct imsgbuf *, void *, size_t, int); 78 static int read_message(struct imsgbuf *, struct imsg *, pid_t); 79 80 static void read_link(struct input_msg *, const char *); 81 82 static __dead void child(int, pid_t, int, char **); 83 84 static void test_file(struct input_file *, size_t); 85 86 static int try_stat(struct input_file *); 87 static int try_empty(struct input_file *); 88 static int try_access(struct input_file *); 89 static int try_text(struct input_file *); 90 static int try_magic(struct input_file *); 91 static int try_unknown(struct input_file *); 92 93 static int bflag; 94 static int cflag; 95 static int iflag; 96 static int Lflag; 97 static int sflag; 98 static int Wflag; 99 100 static char *magicpath; 101 static FILE *magicfp; 102 103 static struct option longopts[] = { 104 { "mime", no_argument, NULL, 'i' }, 105 { "mime-type", no_argument, NULL, 'i' }, 106 { NULL, 0, NULL, 0 } 107 }; 108 109 __dead void 110 usage(void) 111 { 112 fprintf(stderr, "usage: %s [-bchiLsW] file ...\n", __progname); 113 exit(1); 114 } 115 116 int 117 main(int argc, char **argv) 118 { 119 int opt, pair[2], fd, idx, mode, error; 120 char *home; 121 struct passwd *pw; 122 struct imsgbuf ibuf; 123 struct imsg imsg; 124 struct input_msg msg; 125 struct input_ack *ack; 126 pid_t pid, parent; 127 128 tzset(); 129 130 for (;;) { 131 opt = getopt_long(argc, argv, "bchiLsW", longopts, NULL); 132 if (opt == -1) 133 break; 134 switch (opt) { 135 case 'b': 136 bflag = 1; 137 break; 138 case 'c': 139 cflag = 1; 140 break; 141 case 'h': 142 Lflag = 0; 143 break; 144 case 'i': 145 iflag = 1; 146 break; 147 case 'L': 148 Lflag = 1; 149 break; 150 case 's': 151 sflag = 1; 152 break; 153 case 'W': 154 Wflag = 1; 155 break; 156 default: 157 usage(); 158 } 159 } 160 argc -= optind; 161 argv += optind; 162 if (cflag) { 163 if (argc != 0) 164 usage(); 165 } else if (argc == 0) 166 usage(); 167 168 magicfp = NULL; 169 if (geteuid() != 0 && !issetugid()) { 170 home = getenv("HOME"); 171 if (home == NULL || *home == '\0') { 172 pw = getpwuid(getuid()); 173 if (pw != NULL) 174 home = pw->pw_dir; 175 else 176 home = NULL; 177 } 178 if (home != NULL) { 179 xasprintf(&magicpath, "%s/.magic", home); 180 magicfp = fopen(magicpath, "r"); 181 if (magicfp == NULL) 182 free(magicpath); 183 } 184 } 185 if (magicfp == NULL) { 186 magicpath = xstrdup("/etc/magic"); 187 magicfp = fopen(magicpath, "r"); 188 } 189 if (magicfp == NULL) 190 err(1, "%s", magicpath); 191 192 parent = getpid(); 193 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0) 194 err(1, "socketpair"); 195 switch (pid = fork()) { 196 case -1: 197 err(1, "fork"); 198 case 0: 199 close(pair[0]); 200 child(pair[1], parent, argc, argv); 201 } 202 close(pair[1]); 203 204 fclose(magicfp); 205 magicfp = NULL; 206 207 if (cflag) 208 goto wait_for_child; 209 210 imsg_init(&ibuf, pair[0]); 211 for (idx = 0; idx < argc; idx++) { 212 memset(&msg, 0, sizeof msg); 213 msg.idx = idx; 214 215 if (strcmp(argv[idx], "-") == 0) { 216 if (fstat(STDIN_FILENO, &msg.sb) == -1) { 217 fd = -1; 218 msg.error = errno; 219 } else 220 fd = STDIN_FILENO; 221 } else { 222 if (Lflag) 223 error = stat(argv[idx], &msg.sb); 224 else 225 error = lstat(argv[idx], &msg.sb); 226 if (error == -1) { 227 fd = -1; 228 msg.error = errno; 229 } else { 230 /* 231 * pledge(2) doesn't let us pass directory file 232 * descriptors around - but in fact we don't 233 * need them, so just don't open directories or 234 * symlinks (which could be to directories). 235 */ 236 mode = msg.sb.st_mode; 237 if (!S_ISDIR(mode) && !S_ISLNK(mode)) { 238 fd = open(argv[idx], 239 O_RDONLY|O_NONBLOCK); 240 if (fd == -1 && (errno == ENFILE || 241 errno == EMFILE)) 242 err(1, "open"); 243 } else 244 fd = -1; 245 if (S_ISLNK(mode)) 246 read_link(&msg, argv[idx]); 247 } 248 } 249 send_message(&ibuf, &msg, sizeof msg, fd); 250 251 if (read_message(&ibuf, &imsg, pid) == 0) 252 break; 253 if (imsg.hdr.len != IMSG_HEADER_SIZE + sizeof *ack) 254 errx(1, "message too small"); 255 ack = imsg.data; 256 if (ack->idx != idx) 257 errx(1, "index not expected"); 258 imsg_free(&imsg); 259 } 260 261 wait_for_child: 262 close(pair[0]); 263 while (wait(NULL) == -1 && errno != ECHILD) { 264 if (errno != EINTR) 265 err(1, "wait"); 266 } 267 _exit(0); /* let the child flush */ 268 } 269 270 static void 271 send_message(struct imsgbuf *ibuf, void *msg, size_t msglen, int fd) 272 { 273 if (imsg_compose(ibuf, -1, -1, 0, fd, msg, msglen) != 1) 274 err(1, "imsg_compose"); 275 if (imsg_flush(ibuf) != 0) 276 err(1, "imsg_flush"); 277 } 278 279 static int 280 read_message(struct imsgbuf *ibuf, struct imsg *imsg, pid_t from) 281 { 282 int n; 283 284 if ((n = imsg_read(ibuf)) == -1) 285 err(1, "imsg_read"); 286 if (n == 0) 287 return (0); 288 289 if ((n = imsg_get(ibuf, imsg)) == -1) 290 err(1, "imsg_get"); 291 if (n == 0) 292 return (0); 293 294 if ((pid_t)imsg->hdr.pid != from) 295 errx(1, "PIDs don't match"); 296 297 return (n); 298 299 } 300 301 static void 302 read_link(struct input_msg *msg, const char *path) 303 { 304 struct stat sb; 305 char lpath[PATH_MAX]; 306 char *copy, *root; 307 int used; 308 ssize_t size; 309 310 size = readlink(path, lpath, sizeof lpath - 1); 311 if (size == -1) { 312 msg->link_error = errno; 313 return; 314 } 315 lpath[size] = '\0'; 316 317 if (*lpath == '/') 318 strlcpy(msg->link_path, lpath, sizeof msg->link_path); 319 else { 320 copy = xstrdup(path); 321 322 root = dirname(copy); 323 if (*root == '\0' || strcmp(root, ".") == 0 || 324 strcmp (root, "/") == 0) 325 strlcpy(msg->link_path, lpath, sizeof msg->link_path); 326 else { 327 used = snprintf(msg->link_path, sizeof msg->link_path, 328 "%s/%s", root, lpath); 329 if (used < 0 || (size_t)used >= sizeof msg->link_path) { 330 msg->link_error = ENAMETOOLONG; 331 free(copy); 332 return; 333 } 334 } 335 336 free(copy); 337 } 338 339 if (!Lflag && stat(path, &sb) == -1) 340 msg->link_target = errno; 341 } 342 343 static __dead void 344 child(int fd, pid_t parent, int argc, char **argv) 345 { 346 struct passwd *pw; 347 struct magic *m; 348 struct imsgbuf ibuf; 349 struct imsg imsg; 350 struct input_msg *msg; 351 struct input_ack ack; 352 struct input_file inf; 353 int i, idx; 354 size_t len, width = 0; 355 356 if (pledge("stdio getpw recvfd id", NULL) == -1) 357 err(1, "pledge"); 358 359 if (geteuid() == 0) { 360 pw = getpwnam(FILE_USER); 361 if (pw == NULL) 362 errx(1, "unknown user %s", FILE_USER); 363 if (setgroups(1, &pw->pw_gid) != 0) 364 err(1, "setgroups"); 365 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) 366 err(1, "setresgid"); 367 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) 368 err(1, "setresuid"); 369 } 370 371 if (pledge("stdio recvfd", NULL) == -1) 372 err(1, "pledge"); 373 374 m = magic_load(magicfp, magicpath, cflag || Wflag); 375 if (cflag) { 376 magic_dump(m); 377 exit(0); 378 } 379 380 for (i = 0; i < argc; i++) { 381 len = strlen(argv[i]) + 1; 382 if (len > width) 383 width = len; 384 } 385 386 imsg_init(&ibuf, fd); 387 for (;;) { 388 if (read_message(&ibuf, &imsg, parent) == 0) 389 break; 390 if (imsg.hdr.len != IMSG_HEADER_SIZE + sizeof *msg) 391 errx(1, "message too small"); 392 msg = imsg.data; 393 394 idx = msg->idx; 395 if (idx < 0 || idx >= argc) 396 errx(1, "index out of range"); 397 398 memset(&inf, 0, sizeof inf); 399 inf.m = m; 400 inf.msg = msg; 401 402 inf.path = argv[idx]; 403 inf.fd = imsg.fd; 404 405 test_file(&inf, width); 406 407 if (imsg.fd != -1) 408 close(imsg.fd); 409 imsg_free(&imsg); 410 411 ack.idx = idx; 412 send_message(&ibuf, &ack, sizeof ack, -1); 413 } 414 exit(0); 415 } 416 417 static void * 418 fill_buffer(int fd, size_t size, size_t *used) 419 { 420 static void *buffer; 421 ssize_t got; 422 size_t left; 423 void *next; 424 425 if (buffer == NULL) 426 buffer = xmalloc(FILE_READ_SIZE); 427 428 next = buffer; 429 left = size; 430 while (left != 0) { 431 got = read(fd, next, left); 432 if (got == -1) { 433 if (errno == EINTR) 434 continue; 435 return NULL; 436 } 437 if (got == 0) 438 break; 439 next = (char *)next + got; 440 left -= got; 441 } 442 *used = size - left; 443 return buffer; 444 } 445 446 static int 447 load_file(struct input_file *inf) 448 { 449 size_t used; 450 451 if (inf->msg->sb.st_size == 0 && S_ISREG(inf->msg->sb.st_mode)) 452 return (0); /* empty file */ 453 if (inf->msg->sb.st_size == 0 || inf->msg->sb.st_size > FILE_READ_SIZE) 454 inf->size = FILE_READ_SIZE; 455 else 456 inf->size = inf->msg->sb.st_size; 457 458 if (!S_ISREG(inf->msg->sb.st_mode)) 459 goto try_read; 460 461 inf->base = mmap(NULL, inf->size, PROT_READ, MAP_PRIVATE, inf->fd, 0); 462 if (inf->base == MAP_FAILED) 463 goto try_read; 464 inf->mapped = 1; 465 return (0); 466 467 try_read: 468 inf->base = fill_buffer(inf->fd, inf->size, &used); 469 if (inf->base == NULL) { 470 xasprintf(&inf->result, "cannot read '%s' (%s)", inf->path, 471 strerror(errno)); 472 return (1); 473 } 474 inf->size = used; 475 return (0); 476 } 477 478 static int 479 try_stat(struct input_file *inf) 480 { 481 if (inf->msg->error != 0) { 482 xasprintf(&inf->result, "cannot stat '%s' (%s)", inf->path, 483 strerror(inf->msg->error)); 484 return (1); 485 } 486 if (sflag || strcmp(inf->path, "-") == 0) { 487 switch (inf->msg->sb.st_mode & S_IFMT) { 488 case S_IFIFO: 489 if (strcmp(inf->path, "-") != 0) 490 break; 491 case S_IFBLK: 492 case S_IFCHR: 493 case S_IFREG: 494 return (0); 495 } 496 } 497 498 if (iflag && (inf->msg->sb.st_mode & S_IFMT) != S_IFREG) { 499 xasprintf(&inf->result, "application/x-not-regular-file"); 500 return (1); 501 } 502 503 switch (inf->msg->sb.st_mode & S_IFMT) { 504 case S_IFDIR: 505 xasprintf(&inf->result, "directory"); 506 return (1); 507 case S_IFLNK: 508 if (inf->msg->link_error != 0) { 509 xasprintf(&inf->result, "unreadable symlink '%s' (%s)", 510 inf->path, strerror(inf->msg->link_error)); 511 return (1); 512 } 513 if (inf->msg->link_target == ELOOP) 514 xasprintf(&inf->result, "symbolic link in a loop"); 515 else if (inf->msg->link_target != 0) { 516 xasprintf(&inf->result, "broken symbolic link to '%s'", 517 inf->msg->link_path); 518 } else { 519 xasprintf(&inf->result, "symbolic link to '%s'", 520 inf->msg->link_path); 521 } 522 return (1); 523 case S_IFSOCK: 524 xasprintf(&inf->result, "socket"); 525 return (1); 526 case S_IFBLK: 527 xasprintf(&inf->result, "block special (%ld/%ld)", 528 (long)major(inf->msg->sb.st_rdev), 529 (long)minor(inf->msg->sb.st_rdev)); 530 return (1); 531 case S_IFCHR: 532 xasprintf(&inf->result, "character special (%ld/%ld)", 533 (long)major(inf->msg->sb.st_rdev), 534 (long)minor(inf->msg->sb.st_rdev)); 535 return (1); 536 case S_IFIFO: 537 xasprintf(&inf->result, "fifo (named pipe)"); 538 return (1); 539 } 540 return (0); 541 } 542 543 static int 544 try_empty(struct input_file *inf) 545 { 546 if (inf->size != 0) 547 return (0); 548 549 if (iflag) 550 xasprintf(&inf->result, "application/x-empty"); 551 else 552 xasprintf(&inf->result, "empty"); 553 return (1); 554 } 555 556 static int 557 try_access(struct input_file *inf) 558 { 559 char tmp[256] = ""; 560 561 if (inf->msg->sb.st_size == 0 && S_ISREG(inf->msg->sb.st_mode)) 562 return (0); /* empty file */ 563 if (inf->fd != -1) 564 return (0); 565 566 if (inf->msg->sb.st_mode & (S_IWUSR|S_IWGRP|S_IWOTH)) 567 strlcat(tmp, "writable, ", sizeof tmp); 568 if (inf->msg->sb.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) 569 strlcat(tmp, "executable, ", sizeof tmp); 570 if (S_ISREG(inf->msg->sb.st_mode)) 571 strlcat(tmp, "regular file, ", sizeof tmp); 572 strlcat(tmp, "no read permission", sizeof tmp); 573 574 inf->result = xstrdup(tmp); 575 return (1); 576 } 577 578 static int 579 try_text(struct input_file *inf) 580 { 581 const char *type, *s; 582 int flags; 583 584 flags = MAGIC_TEST_TEXT; 585 if (iflag) 586 flags |= MAGIC_TEST_MIME; 587 588 type = text_get_type(inf->base, inf->size); 589 if (type == NULL) 590 return (0); 591 592 s = magic_test(inf->m, inf->base, inf->size, flags); 593 if (s != NULL) { 594 inf->result = xstrdup(s); 595 return (1); 596 } 597 598 s = text_try_words(inf->base, inf->size, flags); 599 if (s != NULL) { 600 if (iflag) 601 inf->result = xstrdup(s); 602 else 603 xasprintf(&inf->result, "%s %s text", type, s); 604 return (1); 605 } 606 607 if (iflag) 608 inf->result = xstrdup("text/plain"); 609 else 610 xasprintf(&inf->result, "%s text", type); 611 return (1); 612 } 613 614 static int 615 try_magic(struct input_file *inf) 616 { 617 const char *s; 618 int flags; 619 620 flags = 0; 621 if (iflag) 622 flags |= MAGIC_TEST_MIME; 623 624 s = magic_test(inf->m, inf->base, inf->size, flags); 625 if (s != NULL) { 626 inf->result = xstrdup(s); 627 return (1); 628 } 629 return (0); 630 } 631 632 static int 633 try_unknown(struct input_file *inf) 634 { 635 if (iflag) 636 xasprintf(&inf->result, "application/x-not-regular-file"); 637 else 638 xasprintf(&inf->result, "data"); 639 return (1); 640 } 641 642 static void 643 test_file(struct input_file *inf, size_t width) 644 { 645 char *label; 646 int stop; 647 648 stop = 0; 649 if (!stop) 650 stop = try_stat(inf); 651 if (!stop) 652 stop = try_access(inf); 653 if (!stop) 654 stop = load_file(inf); 655 if (!stop) 656 stop = try_empty(inf); 657 if (!stop) 658 stop = try_magic(inf); 659 if (!stop) 660 stop = try_text(inf); 661 if (!stop) 662 stop = try_unknown(inf); 663 664 if (bflag) 665 printf("%s\n", inf->result); 666 else { 667 if (strcmp(inf->path, "-") == 0) 668 xasprintf(&label, "/dev/stdin:"); 669 else 670 xasprintf(&label, "%s:", inf->path); 671 printf("%-*s %s\n", (int)width, label, inf->result); 672 free(label); 673 } 674 free(inf->result); 675 676 if (inf->mapped && inf->base != NULL) 677 munmap(inf->base, inf->size); 678 } 679