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 35 #include "libsecureboot.h" 36 #include <verify_file.h> 37 #include <manifests.h> 38 39 #define VE_NOT_CHECKED -42 40 41 #ifdef UNIT_TEST 42 # include <err.h> 43 # define panic warn 44 /* 45 * define MANIFEST_SKIP to Skip - in tests/tvo.c so that 46 * tvo can control the value we use in find_manifest() 47 */ 48 extern char *Skip; 49 # undef MANIFEST_SKIP 50 # define MANIFEST_SKIP Skip 51 # undef VE_DEBUG_LEVEL 52 #endif 53 54 /* 55 * We sometimes need to know if input is verified or not. 56 * The extra slot is for tracking most recently opened. 57 */ 58 static int ve_status[SOPEN_MAX+1]; 59 static int ve_status_state; 60 struct verify_status; 61 struct verify_status *verified_files = NULL; 62 static int loaded_manifests = 0; /* have we loaded anything? */ 63 64 #define VE_STATUS_NONE 1 65 #define VE_STATUS_VALID 2 66 67 /** 68 * @brief set ve status for fd 69 */ 70 static void 71 ve_status_set(int fd, int ves) 72 { 73 if (fd >= 0 && fd < SOPEN_MAX) { 74 ve_status[fd] = ves; 75 ve_status_state = VE_STATUS_VALID; 76 } 77 ve_status[SOPEN_MAX] = ves; 78 } 79 80 /** 81 * @brief get ve status of fd 82 * 83 * What we return depends on ve_status_state. 84 * 85 * @return 86 * @li ve_status[fd] if ve_status_state is valid 87 * @li ve_status[SOPEN_MAX] if ve_status_state is none 88 * @li VE_NOT_CHECKED if ve_status_state uninitialized 89 */ 90 int 91 ve_status_get(int fd) 92 { 93 if (!ve_status_state) { 94 return (VE_NOT_CHECKED); 95 } 96 if (ve_status_state == VE_STATUS_VALID && 97 fd >= 0 && fd < SOPEN_MAX) 98 return (ve_status[fd]); 99 return (ve_status[SOPEN_MAX]); /* most recent */ 100 } 101 102 /** 103 * @brief track verify status 104 * 105 * occasionally loader will make multiple calls 106 * for the same file, we need only check it once. 107 */ 108 struct verify_status { 109 dev_t vs_dev; 110 ino_t vs_ino; 111 int vs_status; 112 struct verify_status *vs_next; 113 }; 114 115 static int 116 is_verified(struct stat *stp) 117 { 118 struct verify_status *vsp; 119 120 for (vsp = verified_files; vsp != NULL; vsp = vsp->vs_next) { 121 if (stp->st_dev == vsp->vs_dev && 122 stp->st_ino == vsp->vs_ino) 123 return (vsp->vs_status); 124 } 125 return (VE_NOT_CHECKED); 126 } 127 128 /* most recent first, since most likely to see repeated calls. */ 129 static void 130 add_verify_status(struct stat *stp, int status) 131 { 132 struct verify_status *vsp; 133 134 vsp = malloc(sizeof(struct verify_status)); 135 vsp->vs_next = verified_files; 136 vsp->vs_dev = stp->st_dev; 137 vsp->vs_ino = stp->st_ino; 138 vsp->vs_status = status; 139 verified_files = vsp; 140 } 141 142 143 /** 144 * @brief 145 * load specified manifest if verified 146 */ 147 int 148 load_manifest(const char *name, const char *prefix, 149 const char *skip, struct stat *stp) 150 { 151 struct stat st; 152 size_t n; 153 int rc; 154 char *content; 155 156 rc = VE_FINGERPRINT_NONE; 157 n = strlen(name); 158 if (n > 4) { 159 if (!stp) { 160 stp = &st; 161 if (stat(name, &st) < 0 || !S_ISREG(st.st_mode)) 162 return (rc); 163 } 164 rc = is_verified(stp); 165 if (rc != VE_NOT_CHECKED) { 166 return (rc); 167 } 168 /* loader has no sense of time */ 169 ve_utc_set(stp->st_mtime); 170 content = (char *)verify_signed(name, VEF_VERBOSE); 171 if (content) { 172 fingerprint_info_add(name, prefix, skip, content, stp); 173 add_verify_status(stp, VE_VERIFIED); 174 loaded_manifests = 1; /* we are verifying! */ 175 DEBUG_PRINTF(3, ("loaded: %s %s %s\n", 176 name, prefix, skip)); 177 rc = 0; 178 } else { 179 rc = VE_FINGERPRINT_WRONG; 180 add_verify_status(stp, rc); /* remember */ 181 } 182 } 183 return (rc); 184 } 185 186 static int 187 find_manifest(const char *name) 188 { 189 struct stat st; 190 char buf[MAXPATHLEN]; 191 char *prefix; 192 char *skip; 193 const char **tp; 194 int rc; 195 196 strncpy(buf, name, MAXPATHLEN - 1); 197 if (!(prefix = strrchr(buf, '/'))) 198 return (-1); 199 *prefix = '\0'; 200 prefix = strdup(buf); 201 rc = VE_FINGERPRINT_NONE; 202 for (tp = manifest_names; *tp; tp++) { 203 snprintf(buf, sizeof(buf), "%s/%s", prefix, *tp); 204 DEBUG_PRINTF(5, ("looking for %s\n", buf)); 205 if (stat(buf, &st) == 0 && st.st_size > 0) { 206 #ifdef MANIFEST_SKIP_ALWAYS /* very unlikely */ 207 skip = MANIFEST_SKIP_ALWAYS; 208 #else 209 #ifdef MANIFEST_SKIP /* rare */ 210 if (*tp[0] == '.') { 211 skip = MANIFEST_SKIP; 212 } else 213 #endif 214 skip = NULL; 215 #endif 216 rc = load_manifest(buf, skip ? prefix : NULL, 217 skip, &st); 218 break; 219 } 220 } 221 free(prefix); 222 return (rc); 223 } 224 225 226 #ifdef LOADER_VERIEXEC_TESTING 227 # define ACCEPT_NO_FP_DEFAULT VE_MUST + 1 228 #else 229 # define ACCEPT_NO_FP_DEFAULT VE_MUST 230 #endif 231 #ifndef VE_VERBOSE_DEFAULT 232 # define VE_VERBOSE_DEFAULT 0 233 #endif 234 235 static int 236 severity_guess(const char *filename) 237 { 238 const char *cp; 239 240 /* Some files like *.conf and *.hints may be unsigned */ 241 if ((cp = strrchr(filename, '.'))) { 242 if (strcmp(cp, ".conf") == 0 || 243 strcmp(cp, ".cookie") == 0 || 244 strcmp(cp, ".hints") == 0) 245 return (VE_TRY); 246 } 247 return (VE_WANT); 248 } 249 250 static void 251 verify_tweak(char *tweak, int *accept_no_fp, int *verbose, int *verifying) 252 { 253 if (strcmp(tweak, "off") == 0) { 254 *verifying = 0; 255 } else if (strcmp(tweak, "strict") == 0) { 256 /* anything caller wants verified must be */ 257 *accept_no_fp = VE_WANT; 258 *verbose = 1; /* warn of anything unverified */ 259 /* treat self test failure as fatal */ 260 if (!ve_self_tests()) { 261 panic("verify self tests failed"); 262 } 263 } else if (strcmp(tweak, "modules") == 0) { 264 /* modules/kernel must be verified */ 265 *accept_no_fp = VE_MUST; 266 } else if (strcmp(tweak, "try") == 0) { 267 /* best effort: always accept no fp */ 268 *accept_no_fp = VE_MUST + 1; 269 } else if (strcmp(tweak, "verbose") == 0) { 270 *verbose = 1; 271 } else if (strcmp(tweak, "quiet") == 0) { 272 *verbose = 0; 273 } 274 } 275 276 /** 277 * @brief verify an open file 278 * 279 * @param[in] fd 280 * open descriptor 281 * 282 * @param[in] filename 283 * path we opened and will use to lookup fingerprint 284 * 285 * @param[in] off 286 * current offset in fd, must be restored on return 287 * 288 * @param[in] severity 289 * indicator of how to handle case of missing fingerprint 290 * 291 * We look for a signed manifest relative to the filename 292 * just opened and verify/load it if needed. 293 * 294 * We then use verify_fd() in libve to actually verify that hash for 295 * open file. If it returns < 0 we look at the severity arg to decide 296 * what to do about it. 297 * 298 * If verify_fd() returns VE_FINGERPRINT_NONE we accept it if severity 299 * is < accept_no_fp. 300 * 301 * @return >= 0 on success < 0 on failure 302 */ 303 int 304 verify_file(int fd, const char *filename, off_t off, int severity) 305 { 306 static int verifying = -1; 307 static int accept_no_fp = ACCEPT_NO_FP_DEFAULT; 308 static int verbose = VE_VERBOSE_DEFAULT; 309 struct stat st; 310 char *cp; 311 int rc; 312 313 if (verifying < 0) { 314 verifying = ve_trust_init(); 315 #ifdef VE_DEBUG_LEVEL 316 ve_debug_set(VE_DEBUG_LEVEL); 317 #endif 318 /* initialize ve_status with default result */ 319 rc = verifying ? VE_NOT_CHECKED : VE_NOT_VERIFYING; 320 ve_status_set(0, rc); 321 ve_status_state = VE_STATUS_NONE; 322 if (verifying) 323 ve_self_tests(); 324 } 325 if (!verifying) 326 return (0); 327 328 if (fd < 0 || fstat(fd, &st) < 0 || !S_ISREG(st.st_mode)) 329 return (0); 330 331 DEBUG_PRINTF(3, ("fd=%d,name='%s',off=%lld,dev=%lld,ino=%lld\n", 332 fd, filename, (long long)off, (long long)st.st_dev, 333 (long long)st.st_ino)); 334 335 336 rc = is_verified(&st); 337 if (rc != VE_NOT_CHECKED) { 338 ve_status_set(fd, rc); 339 return (rc); 340 } 341 rc = find_manifest(filename); 342 if (rc != VE_FINGERPRINT_WRONG && loaded_manifests) { 343 if (severity <= VE_GUESS) 344 severity = severity_guess(filename); 345 if ((rc = verify_fd(fd, filename, off, &st)) >= 0) { 346 if (verbose || severity > VE_WANT) { 347 #if defined(VE_DEBUG_LEVEL) && VE_DEBUG_LEVEL > 0 348 printf("Verified %s %llu,%llu\n", filename, 349 st.st_dev, st.st_ino); 350 #else 351 printf("Verified %s\n", filename); 352 #endif 353 } 354 if (severity < VE_MUST) { /* not a kernel or module */ 355 356 if ((cp = strrchr(filename, '/'))) { 357 cp++; 358 if (strncmp(cp, "loader.ve.", 10) == 0) { 359 cp += 10; 360 verify_tweak(cp, 361 &accept_no_fp, &verbose, 362 &verifying); 363 } 364 } 365 } 366 add_verify_status(&st, rc); 367 ve_status_set(fd, rc); 368 return (rc); 369 } 370 371 if (severity || verbose) 372 printf("Unverified: %s\n", ve_error_get()); 373 if (rc == VE_FINGERPRINT_UNKNOWN && severity < VE_MUST) 374 rc = VE_UNVERIFIED_OK; 375 else if (rc == VE_FINGERPRINT_NONE && severity < accept_no_fp) 376 rc = VE_UNVERIFIED_OK; 377 378 add_verify_status(&st, rc); 379 } 380 #ifdef LOADER_VERIEXEC_TESTING 381 else if (rc != VE_FINGERPRINT_WRONG) { 382 /* 383 * We have not loaded any manifest and 384 * not because of verication failure. 385 * Most likely reason is we have none. 386 * Allow boot to proceed if we are just testing. 387 */ 388 return (VE_UNVERIFIED_OK); 389 } 390 #endif 391 if (rc == VE_FINGERPRINT_WRONG && severity > accept_no_fp) 392 panic("cannot continue"); 393 ve_status_set(fd, rc); 394 return (rc); 395 } 396 397 /** 398 * @brief get hex string for pcr value and export 399 * 400 * In case we are doing measured boot, provide 401 * value of the "pcr" data we have accumulated. 402 */ 403 void 404 verify_pcr_export(void) 405 { 406 #ifdef VE_PCR_SUPPORT 407 char hexbuf[br_sha256_SIZE * 2 + 2]; 408 unsigned char hbuf[br_sha256_SIZE]; 409 char *hex; 410 ssize_t hlen; 411 412 hlen = ve_pcr_get(hbuf, sizeof(hbuf)); 413 if (hlen > 0) { 414 hex = hexdigest(hexbuf, sizeof(hexbuf), hbuf, hlen); 415 if (hex) { 416 hex[hlen*2] = '\0'; /* clobber newline */ 417 setenv("loader.ve.pcr", hex, 1); 418 } 419 } 420 #endif 421 } 422