1 /*- 2 * Copyright (c) 2017-2018, Juniper Networks, Inc. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 14 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 15 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 16 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 17 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 18 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 19 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 /* 26 * Routines to verify files loaded. 27 */ 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 #include <sys/param.h> 32 #include <string.h> 33 #include <sys/queue.h> 34 #include <sys/kenv.h> 35 36 #include "libsecureboot.h" 37 #include <verify_file.h> 38 #include <manifests.h> 39 40 #ifdef UNIT_TEST 41 # include <err.h> 42 # define panic warn 43 /* 44 * define MANIFEST_SKIP to Skip - in tests/tvo.c so that 45 * tvo can control the value we use in find_manifest() 46 */ 47 extern char *Destdir; 48 extern size_t DestdirLen; 49 extern char *Skip; 50 # undef MANIFEST_SKIP 51 # define MANIFEST_SKIP Skip 52 # undef VE_DEBUG_LEVEL 53 #endif 54 55 /* 56 * We sometimes need to know if input is verified or not. 57 * The extra slot is for tracking most recently opened. 58 */ 59 static int ve_status[SOPEN_MAX+1]; 60 static int ve_status_state; 61 struct verify_status; 62 struct verify_status *verified_files = NULL; 63 static int loaded_manifests = 0; /* have we loaded anything? */ 64 65 #define VE_STATUS_NONE 1 66 #define VE_STATUS_VALID 2 67 68 /** 69 * @brief set ve status for fd 70 */ 71 static void 72 ve_status_set(int fd, int ves) 73 { 74 if (fd >= 0 && fd < SOPEN_MAX) { 75 ve_status[fd] = ves; 76 ve_status_state = VE_STATUS_VALID; 77 } 78 ve_status[SOPEN_MAX] = ves; 79 } 80 81 /** 82 * @brief get ve status of fd 83 * 84 * What we return depends on ve_status_state. 85 * 86 * @return 87 * @li ve_status[fd] if ve_status_state is valid 88 * @li ve_status[SOPEN_MAX] if ve_status_state is none 89 * @li VE_NOT_CHECKED if ve_status_state uninitialized 90 */ 91 int 92 ve_status_get(int fd) 93 { 94 if (!ve_status_state) { 95 return (VE_NOT_CHECKED); 96 } 97 if (ve_status_state == VE_STATUS_VALID && 98 fd >= 0 && fd < SOPEN_MAX) 99 return (ve_status[fd]); 100 return (ve_status[SOPEN_MAX]); /* most recent */ 101 } 102 103 /** 104 * @brief track verify status 105 * 106 * occasionally loader will make multiple calls 107 * for the same file, we need only check it once. 108 */ 109 struct verify_status { 110 dev_t vs_dev; 111 ino_t vs_ino; 112 int vs_status; 113 struct verify_status *vs_next; 114 }; 115 116 int 117 is_verified(struct stat *stp) 118 { 119 struct verify_status *vsp; 120 121 if (stp->st_ino > 0) { 122 for (vsp = verified_files; vsp != NULL; vsp = vsp->vs_next) { 123 if (stp->st_dev == vsp->vs_dev && 124 stp->st_ino == vsp->vs_ino) 125 return (vsp->vs_status); 126 } 127 } 128 return (VE_NOT_CHECKED); 129 } 130 131 /* most recent first, since most likely to see repeated calls. */ 132 void 133 add_verify_status(struct stat *stp, int status) 134 { 135 struct verify_status *vsp; 136 137 vsp = malloc(sizeof(struct verify_status)); 138 vsp->vs_next = verified_files; 139 vsp->vs_dev = stp->st_dev; 140 vsp->vs_ino = stp->st_ino; 141 vsp->vs_status = status; 142 verified_files = vsp; 143 } 144 145 146 /** 147 * @brief 148 * load specified manifest if verified 149 */ 150 int 151 load_manifest(const char *name, const char *prefix, 152 const char *skip, struct stat *stp) 153 { 154 struct stat st; 155 size_t n; 156 int rc; 157 char *content; 158 159 rc = VE_FINGERPRINT_NONE; 160 n = strlen(name); 161 if (n > 4) { 162 if (!stp) { 163 stp = &st; 164 if (stat(name, &st) < 0 || !S_ISREG(st.st_mode)) 165 return (rc); 166 } 167 rc = is_verified(stp); 168 if (rc != VE_NOT_CHECKED) { 169 return (rc); 170 } 171 /* loader has no sense of time */ 172 ve_utc_set(stp->st_mtime); 173 content = (char *)verify_signed(name, VEF_VERBOSE); 174 if (content) { 175 #ifdef UNIT_TEST 176 if (DestdirLen > 0 && 177 strncmp(name, Destdir, DestdirLen) == 0) { 178 name += DestdirLen; 179 if (prefix && 180 strncmp(prefix, Destdir, DestdirLen) == 0) 181 prefix += DestdirLen; 182 } 183 #endif 184 fingerprint_info_add(name, prefix, skip, content, stp); 185 add_verify_status(stp, VE_VERIFIED); 186 loaded_manifests = 1; /* we are verifying! */ 187 DEBUG_PRINTF(3, ("loaded: %s %s %s\n", 188 name, prefix, skip)); 189 rc = VE_VERIFIED; 190 } else { 191 rc = VE_FINGERPRINT_WRONG; 192 add_verify_status(stp, rc); /* remember */ 193 } 194 } 195 return (rc); 196 } 197 198 static int 199 find_manifest(const char *name) 200 { 201 struct stat st; 202 char buf[MAXPATHLEN]; 203 char *prefix; 204 char *skip; 205 const char **tp; 206 int rc; 207 208 strncpy(buf, name, MAXPATHLEN - 1); 209 if (!(prefix = strrchr(buf, '/'))) 210 return (-1); 211 *prefix = '\0'; 212 prefix = strdup(buf); 213 rc = VE_FINGERPRINT_NONE; 214 for (tp = manifest_names; *tp; tp++) { 215 snprintf(buf, sizeof(buf), "%s/%s", prefix, *tp); 216 DEBUG_PRINTF(5, ("looking for %s\n", buf)); 217 if (stat(buf, &st) == 0 && st.st_size > 0) { 218 #ifdef MANIFEST_SKIP_ALWAYS /* very unlikely */ 219 skip = MANIFEST_SKIP_ALWAYS; 220 #else 221 #ifdef MANIFEST_SKIP /* rare */ 222 if (*tp[0] == '.') { 223 skip = MANIFEST_SKIP; 224 } else 225 #endif 226 skip = NULL; 227 #endif 228 rc = load_manifest(buf, skip ? prefix : NULL, 229 skip, &st); 230 break; 231 } 232 } 233 free(prefix); 234 return (rc); 235 } 236 237 238 #ifdef LOADER_VERIEXEC_TESTING 239 # define ACCEPT_NO_FP_DEFAULT VE_MUST + 1 240 #else 241 # define ACCEPT_NO_FP_DEFAULT VE_MUST 242 #endif 243 #ifndef VE_VERBOSE_DEFAULT 244 # define VE_VERBOSE_DEFAULT 0 245 #endif 246 247 static int 248 severity_guess(const char *filename) 249 { 250 const char *cp; 251 252 /* Some files like *.conf and *.hints may be unsigned */ 253 if ((cp = strrchr(filename, '.'))) { 254 if (strcmp(cp, ".conf") == 0 || 255 strcmp(cp, ".cookie") == 0 || 256 strcmp(cp, ".hints") == 0) 257 return (VE_TRY); 258 } 259 return (VE_WANT); 260 } 261 262 static int Verifying = -1; /* 0 if not verifying */ 263 264 static void 265 verify_tweak(int fd, off_t off, struct stat *stp, 266 char *tweak, int *accept_no_fp, 267 int *verbose) 268 { 269 if (strcmp(tweak, "off") == 0) { 270 Verifying = 0; 271 } else if (strcmp(tweak, "strict") == 0) { 272 /* anything caller wants verified must be */ 273 *accept_no_fp = VE_WANT; 274 *verbose = 1; /* warn of anything unverified */ 275 /* treat self test failure as fatal */ 276 if (!ve_self_tests()) { 277 panic("verify self tests failed"); 278 } 279 } else if (strcmp(tweak, "modules") == 0) { 280 /* modules/kernel must be verified */ 281 *accept_no_fp = VE_MUST; 282 } else if (strcmp(tweak, "try") == 0) { 283 /* best effort: always accept no fp */ 284 *accept_no_fp = VE_MUST + 1; 285 } else if (strcmp(tweak, "verbose") == 0) { 286 *verbose = 1; 287 } else if (strcmp(tweak, "quiet") == 0) { 288 *verbose = 0; 289 } else if (strncmp(tweak, "trust", 5) == 0) { 290 /* content is trust anchor to add or revoke */ 291 unsigned char *ucp; 292 size_t num; 293 294 if (off > 0) 295 lseek(fd, 0, SEEK_SET); 296 ucp = read_fd(fd, stp->st_size); 297 if (ucp == NULL) 298 return; 299 if (strstr(tweak, "revoke")) { 300 num = ve_trust_anchors_revoke(ucp, stp->st_size); 301 DEBUG_PRINTF(3, ("revoked %d trust anchors\n", 302 (int) num)); 303 } else { 304 num = ve_trust_anchors_add_buf(ucp, stp->st_size); 305 DEBUG_PRINTF(3, ("added %d trust anchors\n", 306 (int) num)); 307 } 308 } 309 } 310 311 #ifndef VE_DEBUG_LEVEL 312 # define VE_DEBUG_LEVEL 0 313 #endif 314 315 static int 316 getenv_int(const char *var, int def) 317 { 318 const char *cp; 319 char *ep; 320 long val; 321 322 val = def; 323 cp = getenv(var); 324 if (cp && *cp) { 325 val = strtol(cp, &ep, 0); 326 if ((ep && *ep) || val != (int)val) { 327 val = def; 328 } 329 } 330 return (int)val; 331 } 332 333 334 /** 335 * @brief prepare to verify an open file 336 * 337 * @param[in] fd 338 * open descriptor 339 * 340 * @param[in] filename 341 * path we opened and will use to lookup fingerprint 342 * 343 * @param[in] stp 344 * stat pointer so we can check file type 345 */ 346 int 347 verify_prep(int fd, const char *filename, off_t off, struct stat *stp, 348 const char *caller) 349 { 350 int rc; 351 352 if (Verifying < 0) { 353 Verifying = ve_trust_init(); 354 #ifndef UNIT_TEST 355 ve_debug_set(getenv_int("VE_DEBUG_LEVEL", VE_DEBUG_LEVEL)); 356 #endif 357 /* initialize ve_status with default result */ 358 rc = Verifying ? VE_NOT_CHECKED : VE_NOT_VERIFYING; 359 ve_status_set(0, rc); 360 ve_status_state = VE_STATUS_NONE; 361 if (Verifying) { 362 ve_self_tests(); 363 ve_anchor_verbose_set(1); 364 } 365 } 366 if (!Verifying || fd < 0) 367 return (0); 368 if (stp) { 369 if (fstat(fd, stp) < 0 || !S_ISREG(stp->st_mode)) 370 return (0); 371 } 372 DEBUG_PRINTF(2, 373 ("verify_prep: caller=%s,fd=%d,name='%s',off=%lld,dev=%lld,ino=%lld\n", 374 caller, fd, filename, (long long)off, (long long)stp->st_dev, 375 (long long)stp->st_ino)); 376 rc = is_verified(stp); 377 DEBUG_PRINTF(4,("verify_prep: is_verified()->%d\n", rc)); 378 if (rc == VE_NOT_CHECKED) { 379 rc = find_manifest(filename); 380 } else { 381 ve_status_set(fd, rc); 382 } 383 return (rc); 384 } 385 386 /** 387 * @brief verify an open file 388 * 389 * @param[in] fd 390 * open descriptor 391 * 392 * @param[in] filename 393 * path we opened and will use to lookup fingerprint 394 * 395 * @param[in] off 396 * current offset in fd, must be restored on return 397 * 398 * @param[in] severity 399 * indicator of how to handle case of missing fingerprint 400 * 401 * We look for a signed manifest relative to the filename 402 * just opened and verify/load it if needed. 403 * 404 * We then use verify_fd() in libve to actually verify that hash for 405 * open file. If it returns < 0 we look at the severity arg to decide 406 * what to do about it. 407 * 408 * If verify_fd() returns VE_FINGERPRINT_NONE we accept it if severity 409 * is < accept_no_fp. 410 * 411 * @return >= 0 on success < 0 on failure 412 */ 413 int 414 verify_file(int fd, const char *filename, off_t off, int severity, 415 const char *caller) 416 { 417 static int once; 418 static int accept_no_fp = ACCEPT_NO_FP_DEFAULT; 419 static int verbose = VE_VERBOSE_DEFAULT; 420 struct stat st; 421 char *cp; 422 int rc; 423 424 rc = verify_prep(fd, filename, off, &st, caller); 425 426 if (!rc) 427 return (0); 428 429 if (!once) { 430 once++; 431 verbose = getenv_int("VE_VERBOSE", VE_VERBOSE_DEFAULT); 432 } 433 434 if (rc != VE_FINGERPRINT_WRONG && loaded_manifests) { 435 if (severity <= VE_GUESS) 436 severity = severity_guess(filename); 437 #ifdef VE_PCR_SUPPORT 438 /* 439 * Only update pcr with things that must verify 440 * these tend to be processed in a more deterministic 441 * order, which makes our pseudo pcr more useful. 442 */ 443 ve_pcr_updating_set((severity == VE_MUST)); 444 #endif 445 #ifdef UNIT_TEST 446 if (DestdirLen > 0 && 447 strncmp(filename, Destdir, DestdirLen) == 0) { 448 filename += DestdirLen; 449 } 450 #endif 451 if ((rc = verify_fd(fd, filename, off, &st)) >= 0) { 452 if (verbose || severity > VE_WANT) { 453 #if defined(VE_DEBUG_LEVEL) && VE_DEBUG_LEVEL > 0 454 printf("%serified %s %llu,%llu\n", 455 (rc == VE_FINGERPRINT_IGNORE) ? "Unv" : "V", 456 filename, 457 (long long)st.st_dev, (long long)st.st_ino); 458 #else 459 printf("%serified %s\n", 460 (rc == VE_FINGERPRINT_IGNORE) ? "Unv" : "V", 461 filename); 462 #endif 463 } 464 if (severity < VE_MUST) { /* not a kernel or module */ 465 if ((cp = strrchr(filename, '/'))) { 466 cp++; 467 if (strncmp(cp, "loader.ve.", 10) == 0) { 468 cp += 10; 469 verify_tweak(fd, off, &st, cp, 470 &accept_no_fp, &verbose); 471 } 472 } 473 } 474 add_verify_status(&st, rc); 475 ve_status_set(fd, rc); 476 return (rc); 477 } 478 479 if (severity || verbose || rc == VE_FINGERPRINT_WRONG) 480 printf("Unverified: %s\n", ve_error_get()); 481 if (rc == VE_FINGERPRINT_UNKNOWN && severity < VE_MUST) 482 rc = VE_UNVERIFIED_OK; 483 else if (rc == VE_FINGERPRINT_NONE && severity < accept_no_fp) 484 rc = VE_UNVERIFIED_OK; 485 486 add_verify_status(&st, rc); 487 } 488 #ifdef LOADER_VERIEXEC_TESTING 489 else if (rc != VE_FINGERPRINT_WRONG) { 490 /* 491 * We have not loaded any manifest and 492 * not because of verication failure. 493 * Most likely reason is we have none. 494 * Allow boot to proceed if we are just testing. 495 */ 496 return (VE_UNVERIFIED_OK); 497 } 498 #endif 499 if (rc == VE_FINGERPRINT_WRONG && severity > accept_no_fp) 500 panic("cannot continue"); 501 ve_status_set(fd, rc); 502 return (rc); 503 } 504 505 /** 506 * @brief get hex string for pcr value and export 507 * 508 * In case we are doing measured boot, provide 509 * value of the "pcr" data we have accumulated. 510 */ 511 void 512 verify_pcr_export(void) 513 { 514 #ifdef VE_PCR_SUPPORT 515 char hexbuf[br_sha256_SIZE * 2 + 2]; 516 unsigned char hbuf[br_sha256_SIZE]; 517 char *hinfo; 518 char *hex; 519 ssize_t hlen; 520 521 hlen = ve_pcr_get(hbuf, sizeof(hbuf)); 522 if (hlen > 0) { 523 hex = hexdigest(hexbuf, sizeof(hexbuf), hbuf, hlen); 524 if (hex) { 525 hex[hlen*2] = '\0'; /* clobber newline */ 526 setenv("loader.ve.pcr", hex, 1); 527 DEBUG_PRINTF(1, 528 ("%s: setenv(loader.ve.pcr, %s\n", __func__, 529 hex)); 530 hinfo = ve_pcr_hashed_get(1); 531 if (hinfo) { 532 setenv("loader.ve.hashed", hinfo, 1); 533 DEBUG_PRINTF(1, 534 ("%s: setenv(loader.ve.hashed, %s\n", 535 __func__, hinfo)); 536 if ((hlen = strlen(hinfo)) > KENV_MVALLEN) { 537 /* 538 * bump kenv_mvallen 539 * roundup to multiple of KENV_MVALLEN 540 */ 541 char mvallen[16]; 542 543 hlen += KENV_MVALLEN - 544 (hlen % KENV_MVALLEN); 545 if (snprintf(mvallen, sizeof(mvallen), 546 "%d", (int) hlen) < sizeof(mvallen)) 547 setenv("kenv_mvallen", mvallen, 1); 548 } 549 free(hinfo); 550 } 551 } 552 } 553 #endif 554 } 555