Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved. |
| 3 | * |
| 4 | * Redistribution and use in source and binary forms, with or without |
| 5 | * modification, are permitted provided that the following conditions are met: |
| 6 | * |
| 7 | * Redistributions of source code must retain the above copyright notice, this |
| 8 | * list of conditions and the following disclaimer. |
| 9 | * |
| 10 | * Redistributions in binary form must reproduce the above copyright notice, |
| 11 | * this list of conditions and the following disclaimer in the documentation |
| 12 | * and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * Neither the name of ARM nor the names of its contributors may be used |
| 15 | * to endorse or promote products derived from this software without specific |
| 16 | * prior written permission. |
| 17 | * |
| 18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| 19 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 20 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 21 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| 22 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 23 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 24 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| 25 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| 26 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| 27 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 28 | * POSSIBILITY OF SUCH DAMAGE. |
| 29 | */ |
| 30 | |
| 31 | /* Authentication module based on PolarSSL */ |
| 32 | |
| 33 | #include <stddef.h> |
| 34 | |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 35 | #include <auth.h> |
| 36 | #include <debug.h> |
| 37 | #include <platform.h> |
| 38 | #include <platform_def.h> |
| 39 | #include <platform_oid.h> |
| 40 | |
| 41 | #include <polarssl/memory_buffer_alloc.h> |
| 42 | #include <polarssl/oid.h> |
| 43 | #include <polarssl/platform.h> |
| 44 | #include <polarssl/sha256.h> |
| 45 | #include <polarssl/x509_crt.h> |
| 46 | |
| 47 | /* |
| 48 | * At each authentication stage, the module is responsible for extracting and |
| 49 | * storing those elements (keys, hashes, etc.) that will be needed later on |
| 50 | * during the Trusted Boot process. |
| 51 | */ |
| 52 | |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 53 | /* Maximum OID string length ("a.b.c.d.e.f ...") */ |
| 54 | #define MAX_OID_STR_LEN 64 |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 55 | |
| 56 | /* |
| 57 | * An 8 KB stack has been proven to be enough for the current Trusted Boot |
| 58 | * process |
| 59 | */ |
| 60 | #define POLARSSL_HEAP_SIZE (8*1024) |
| 61 | static unsigned char heap[POLARSSL_HEAP_SIZE]; |
| 62 | |
| 63 | /* |
| 64 | * RSA public keys: |
| 65 | * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 3 |
| 66 | * algorithm AlgorithmIdentifier, 1 + 1 (sequence) |
| 67 | * + 1 + 1 + 9 (rsa oid) |
| 68 | * + 1 + 1 (params null) |
| 69 | * subjectPublicKey BIT STRING } 1 + 3 + (1 + below) |
| 70 | * RSAPublicKey ::= SEQUENCE { 1 + 3 |
| 71 | * modulus INTEGER, -- n 1 + 3 + MPI_MAX + 1 |
| 72 | * publicExponent INTEGER -- e 1 + 3 + MPI_MAX + 1 |
| 73 | * } |
| 74 | * |
| 75 | * POLARSSL_MPI_MAX_SIZE is set to 256 bytes (RSA-2048 bit keys) in the |
| 76 | * configuration file |
| 77 | */ |
| 78 | #define RSA_PUB_DER_MAX_BYTES 38 + 2 * POLARSSL_MPI_MAX_SIZE |
| 79 | |
| 80 | /* |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 81 | * SHA256: |
| 82 | * DigestInfo ::= SEQUENCE { 1 + 1 |
| 83 | * digestAlgorithm AlgorithmIdentifier, + 1 + 1 (sequence) |
| 84 | * + 1 + 1 + 9 (sha256 oid) |
| 85 | * + 1 + 1 (params null) |
| 86 | * digest OCTET STRING + 1 + 1 + 32 (sha256) |
| 87 | * } |
| 88 | */ |
| 89 | #define SHA256_BYTES 32 |
| 90 | #define SHA256_DER_BYTES (19 + SHA256_BYTES) |
| 91 | |
| 92 | /* |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 93 | * Buffer for storing public keys extracted from certificates while they are |
| 94 | * verified |
| 95 | */ |
| 96 | static unsigned char pk_buf[RSA_PUB_DER_MAX_BYTES]; |
| 97 | |
| 98 | /* We use this variable to parse and authenticate the certificates */ |
| 99 | static x509_crt cert; |
| 100 | |
| 101 | /* BL specific variables */ |
| 102 | #if IMAGE_BL1 |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 103 | static unsigned char sha_bl2[SHA256_DER_BYTES]; |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 104 | #elif IMAGE_BL2 |
| 105 | /* Buffers to store the hash of BL3-x images */ |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 106 | static unsigned char sha_bl30[SHA256_DER_BYTES]; |
| 107 | static unsigned char sha_bl31[SHA256_DER_BYTES]; |
| 108 | static unsigned char sha_bl32[SHA256_DER_BYTES]; |
| 109 | static unsigned char sha_bl33[SHA256_DER_BYTES]; |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 110 | /* Buffers to store the Trusted and Non-Trusted world public keys */ |
| 111 | static unsigned char tz_world_pk[RSA_PUB_DER_MAX_BYTES]; |
| 112 | static unsigned char ntz_world_pk[RSA_PUB_DER_MAX_BYTES]; |
| 113 | static size_t tz_world_pk_len, ntz_world_pk_len; |
| 114 | /* Buffer to store the BL3-x public keys */ |
| 115 | static unsigned char content_pk[RSA_PUB_DER_MAX_BYTES]; |
| 116 | static size_t content_pk_len; |
| 117 | #endif |
| 118 | |
| 119 | |
| 120 | static int x509_get_crt_ext_data(const unsigned char **ext_data, |
| 121 | size_t *ext_len, |
| 122 | x509_crt *crt, |
| 123 | const char *oid) |
| 124 | { |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 125 | int ret, oid_len; |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 126 | size_t len; |
| 127 | unsigned char *end_ext_data, *end_ext_octet; |
| 128 | unsigned char *p; |
| 129 | const unsigned char *end; |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 130 | char oid_str[MAX_OID_STR_LEN]; |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 131 | |
| 132 | p = crt->v3_ext.p; |
| 133 | end = crt->v3_ext.p + crt->v3_ext.len; |
| 134 | |
| 135 | ret = asn1_get_tag(&p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE); |
| 136 | if (ret != 0) |
| 137 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + ret; |
| 138 | |
| 139 | if (end != p + len) |
| 140 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + |
| 141 | POLARSSL_ERR_ASN1_LENGTH_MISMATCH; |
| 142 | |
| 143 | while (p < end) { |
| 144 | /* |
| 145 | * Extension ::= SEQUENCE { |
| 146 | * extnID OBJECT IDENTIFIER, |
| 147 | * critical BOOLEAN DEFAULT FALSE, |
| 148 | * extnValue OCTET STRING } |
| 149 | */ |
| 150 | x509_buf extn_oid = {0, 0, NULL}; |
| 151 | int is_critical = 0; /* DEFAULT FALSE */ |
| 152 | |
| 153 | ret = asn1_get_tag(&p, end, &len, |
| 154 | ASN1_CONSTRUCTED | ASN1_SEQUENCE); |
| 155 | if (ret != 0) |
| 156 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + ret; |
| 157 | |
| 158 | end_ext_data = p + len; |
| 159 | |
| 160 | /* Get extension ID */ |
| 161 | extn_oid.tag = *p; |
| 162 | |
| 163 | ret = asn1_get_tag(&p, end, &extn_oid.len, ASN1_OID); |
| 164 | if (ret != 0) |
| 165 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + ret; |
| 166 | |
| 167 | extn_oid.p = p; |
| 168 | p += extn_oid.len; |
| 169 | |
| 170 | if ((end - p) < 1) |
| 171 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + |
| 172 | POLARSSL_ERR_ASN1_OUT_OF_DATA; |
| 173 | |
| 174 | /* Get optional critical */ |
| 175 | ret = asn1_get_bool(&p, end_ext_data, &is_critical); |
| 176 | if (ret != 0 && (ret != POLARSSL_ERR_ASN1_UNEXPECTED_TAG)) |
| 177 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + ret; |
| 178 | |
| 179 | /* Data should be octet string type */ |
| 180 | ret = asn1_get_tag(&p, end_ext_data, &len, ASN1_OCTET_STRING); |
| 181 | if (ret != 0) |
| 182 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + ret; |
| 183 | |
| 184 | end_ext_octet = p + len; |
| 185 | |
| 186 | if (end_ext_octet != end_ext_data) |
| 187 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + |
| 188 | POLARSSL_ERR_ASN1_LENGTH_MISMATCH; |
| 189 | |
| 190 | /* Detect requested extension */ |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 191 | oid_len = oid_get_numeric_string(oid_str, |
| 192 | MAX_OID_STR_LEN, &extn_oid); |
| 193 | if (oid_len == POLARSSL_ERR_OID_BUF_TOO_SMALL) |
| 194 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + |
| 195 | POLARSSL_ERR_ASN1_BUF_TOO_SMALL; |
| 196 | if ((oid_len == strlen(oid_str)) && !strcmp(oid, oid_str)) { |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 197 | *ext_data = p; |
| 198 | *ext_len = len; |
| 199 | return 0; |
| 200 | } |
| 201 | |
| 202 | /* Next */ |
| 203 | p = end_ext_octet; |
| 204 | } |
| 205 | |
| 206 | if (p != end) |
| 207 | return POLARSSL_ERR_X509_INVALID_EXTENSIONS + |
| 208 | POLARSSL_ERR_ASN1_LENGTH_MISMATCH; |
| 209 | |
| 210 | return POLARSSL_ERR_X509_UNKNOWN_OID; |
| 211 | } |
| 212 | |
| 213 | #if IMAGE_BL1 |
| 214 | /* |
| 215 | * Parse and verify the BL2 certificate |
| 216 | * |
| 217 | * This function verifies the integrity of the BL2 certificate, checks that it |
| 218 | * has been signed with the ROT key and extracts the BL2 hash stored in the |
| 219 | * certificate so it can be matched later against the calculated hash. |
| 220 | * |
| 221 | * Return: 0 = success, Otherwise = error |
| 222 | */ |
| 223 | static int check_bl2_cert(unsigned char *buf, size_t len) |
| 224 | { |
| 225 | const unsigned char *p; |
| 226 | size_t sz; |
| 227 | int err, flags; |
| 228 | |
| 229 | x509_crt_init(&cert); |
| 230 | |
| 231 | /* Parse the BL2 certificate */ |
| 232 | err = x509_crt_parse(&cert, buf, len); |
| 233 | if (err) { |
| 234 | ERROR("BL2 certificate parse error %d.\n", err); |
| 235 | goto error; |
| 236 | } |
| 237 | |
| 238 | /* Check that it has been signed with the ROT key */ |
| 239 | err = pk_write_pubkey_der(&cert.pk, pk_buf, sizeof(pk_buf)); |
| 240 | if (err < 0) { |
| 241 | ERROR("Error loading ROT key in DER format %d.\n", err); |
| 242 | goto error; |
| 243 | } |
| 244 | |
| 245 | sz = (size_t)err; |
| 246 | p = pk_buf + sizeof(pk_buf) - sz; |
| 247 | |
| 248 | err = plat_match_rotpk(p, sz); |
| 249 | if (err) { |
| 250 | ERROR("ROT and BL2 certificate key mismatch\n"); |
| 251 | goto error; |
| 252 | } |
| 253 | |
| 254 | /* Verify certificate */ |
| 255 | err = x509_crt_verify(&cert, &cert, NULL, NULL, &flags, NULL, NULL); |
| 256 | if (err) { |
| 257 | ERROR("BL2 certificate verification error %d. Flags: 0x%x.\n", |
| 258 | err, flags); |
| 259 | goto error; |
| 260 | } |
| 261 | |
| 262 | /* Extract BL2 image hash from certificate */ |
| 263 | err = x509_get_crt_ext_data(&p, &sz, &cert, BL2_HASH_OID); |
| 264 | if (err) { |
| 265 | ERROR("Cannot read BL2 hash from certificate\n"); |
| 266 | goto error; |
| 267 | } |
| 268 | |
Juan Castillo | f18daf7 | 2015-03-10 15:18:55 +0000 | [diff] [blame] | 269 | if (sz != SHA256_DER_BYTES) { |
| 270 | ERROR("Wrong BL2 hash size: %lu\n", sz); |
| 271 | err = 1; |
| 272 | goto error; |
| 273 | } |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 274 | memcpy(sha_bl2, p, SHA256_DER_BYTES); |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 275 | |
| 276 | error: |
| 277 | x509_crt_free(&cert); |
| 278 | |
| 279 | return err; |
| 280 | } |
| 281 | #endif /* IMAGE_BL1 */ |
| 282 | |
| 283 | #if IMAGE_BL2 |
| 284 | static int check_trusted_key_cert(unsigned char *buf, size_t len) |
| 285 | { |
| 286 | const unsigned char *p; |
| 287 | size_t sz; |
| 288 | int err, flags; |
| 289 | |
| 290 | x509_crt_init(&cert); |
| 291 | |
| 292 | /* Parse the Trusted Key certificate */ |
| 293 | err = x509_crt_parse(&cert, buf, len); |
| 294 | if (err) { |
| 295 | ERROR("Trusted Key certificate parse error %d.\n", err); |
| 296 | goto error; |
| 297 | } |
| 298 | |
| 299 | /* Verify Trusted Key certificate */ |
| 300 | err = x509_crt_verify(&cert, &cert, NULL, NULL, &flags, NULL, NULL); |
| 301 | if (err) { |
| 302 | ERROR("Trusted Key certificate verification error %d. Flags: " |
| 303 | "0x%x.\n", err, flags); |
| 304 | goto error; |
| 305 | } |
| 306 | |
| 307 | /* Check that it has been signed with the ROT key */ |
| 308 | err = pk_write_pubkey_der(&cert.pk, pk_buf, sizeof(pk_buf)); |
| 309 | if (err < 0) { |
| 310 | ERROR("Error loading ROT key in DER format %d.\n", err); |
| 311 | goto error; |
| 312 | } |
| 313 | |
| 314 | sz = (size_t)err; |
| 315 | p = pk_buf + sizeof(pk_buf) - sz; |
| 316 | |
| 317 | if (plat_match_rotpk(p, sz)) { |
| 318 | ERROR("ROT and Trusted Key certificate key mismatch\n"); |
| 319 | goto error; |
| 320 | } |
| 321 | |
| 322 | /* Extract Trusted World key from extensions */ |
| 323 | err = x509_get_crt_ext_data(&p, &tz_world_pk_len, |
| 324 | &cert, TZ_WORLD_PK_OID); |
| 325 | if (err) { |
| 326 | ERROR("Cannot read Trusted World key\n"); |
| 327 | goto error; |
| 328 | } |
| 329 | |
Juan Castillo | f18daf7 | 2015-03-10 15:18:55 +0000 | [diff] [blame] | 330 | if (tz_world_pk_len > RSA_PUB_DER_MAX_BYTES) { |
| 331 | ERROR("Wrong RSA key size: %lu\n", tz_world_pk_len); |
| 332 | err = 1; |
| 333 | goto error; |
| 334 | } |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 335 | memcpy(tz_world_pk, p, tz_world_pk_len); |
| 336 | |
| 337 | /* Extract Non-Trusted World key from extensions */ |
| 338 | err = x509_get_crt_ext_data(&p, &ntz_world_pk_len, |
| 339 | &cert, NTZ_WORLD_PK_OID); |
| 340 | if (err) { |
| 341 | ERROR("Cannot read Non-Trusted World key\n"); |
| 342 | goto error; |
| 343 | } |
| 344 | |
Juan Castillo | f18daf7 | 2015-03-10 15:18:55 +0000 | [diff] [blame] | 345 | if (ntz_world_pk_len > RSA_PUB_DER_MAX_BYTES) { |
| 346 | ERROR("Wrong RSA key size: %lu\n", ntz_world_pk_len); |
| 347 | err = 1; |
| 348 | goto error; |
| 349 | } |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 350 | memcpy(ntz_world_pk, p, ntz_world_pk_len); |
| 351 | |
| 352 | error: |
| 353 | x509_crt_free(&cert); |
| 354 | |
| 355 | return err; |
| 356 | } |
| 357 | |
| 358 | static int check_bl3x_key_cert(const unsigned char *buf, size_t len, |
| 359 | const unsigned char *i_key, size_t i_key_len, |
| 360 | unsigned char *s_key, size_t *s_key_len, |
| 361 | const char *key_oid) |
| 362 | { |
| 363 | const unsigned char *p; |
| 364 | size_t sz; |
| 365 | int err, flags; |
| 366 | |
| 367 | x509_crt_init(&cert); |
| 368 | |
| 369 | /* Parse key certificate */ |
| 370 | err = x509_crt_parse(&cert, buf, len); |
| 371 | if (err) { |
| 372 | ERROR("Key certificate parse error %d.\n", err); |
| 373 | goto error; |
| 374 | } |
| 375 | |
| 376 | /* Verify certificate */ |
| 377 | err = x509_crt_verify(&cert, &cert, NULL, NULL, &flags, NULL, NULL); |
| 378 | if (err) { |
| 379 | ERROR("Key certificate verification error %d. Flags: " |
| 380 | "0x%x.\n", err, flags); |
| 381 | goto error; |
| 382 | } |
| 383 | |
| 384 | /* Check that the certificate has been signed by the issuer */ |
| 385 | err = pk_write_pubkey_der(&cert.pk, pk_buf, sizeof(pk_buf)); |
| 386 | if (err < 0) { |
| 387 | ERROR("Error loading key in DER format %d.\n", err); |
| 388 | goto error; |
| 389 | } |
| 390 | |
| 391 | sz = (size_t)err; |
| 392 | p = pk_buf + sizeof(pk_buf) - sz; |
| 393 | if ((sz != i_key_len) || memcmp(p, i_key, sz)) { |
| 394 | ERROR("Key certificate not signed with issuer key\n"); |
| 395 | err = 1; |
| 396 | goto error; |
| 397 | } |
| 398 | |
| 399 | /* Get the content certificate key */ |
| 400 | err = x509_get_crt_ext_data(&p, &sz, &cert, key_oid); |
| 401 | if (err) { |
| 402 | ERROR("Extension %s not found in Key certificate\n", key_oid); |
| 403 | goto error; |
| 404 | } |
| 405 | |
Juan Castillo | f18daf7 | 2015-03-10 15:18:55 +0000 | [diff] [blame] | 406 | if (sz > RSA_PUB_DER_MAX_BYTES) { |
| 407 | ERROR("Wrong RSA key size: %lu\n", sz); |
| 408 | err = 1; |
| 409 | goto error; |
| 410 | } |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 411 | memcpy(s_key, p, sz); |
| 412 | *s_key_len = sz; |
| 413 | |
| 414 | error: |
| 415 | x509_crt_free(&cert); |
| 416 | |
| 417 | return err; |
| 418 | } |
| 419 | |
| 420 | static int check_bl3x_cert(unsigned char *buf, size_t len, |
| 421 | const unsigned char *i_key, size_t i_key_len, |
| 422 | const char *hash_oid, unsigned char *sha) |
| 423 | { |
| 424 | const unsigned char *p; |
| 425 | size_t sz; |
| 426 | int err, flags; |
| 427 | |
| 428 | x509_crt_init(&cert); |
| 429 | |
| 430 | /* Parse BL31 content certificate */ |
| 431 | err = x509_crt_parse(&cert, buf, len); |
| 432 | if (err) { |
| 433 | ERROR("Content certificate parse error %d.\n", err); |
| 434 | goto error; |
| 435 | } |
| 436 | |
| 437 | /* Verify certificate */ |
| 438 | err = x509_crt_verify(&cert, &cert, NULL, NULL, &flags, NULL, NULL); |
| 439 | if (err) { |
| 440 | ERROR("Content certificate verification error %d. Flags: " |
| 441 | "0x%x.\n", err, flags); |
| 442 | goto error; |
| 443 | } |
| 444 | |
| 445 | /* Check that content certificate has been signed with the content |
| 446 | * certificate key corresponding to this image */ |
| 447 | sz = pk_write_pubkey_der(&cert.pk, pk_buf, sizeof(pk_buf)); |
| 448 | p = pk_buf + sizeof(pk_buf) - sz; |
| 449 | |
| 450 | if ((sz != i_key_len) || memcmp(p, i_key, sz)) { |
| 451 | ERROR("Content certificate not signed with content " |
| 452 | "certificate key\n"); |
| 453 | err = 1; |
| 454 | goto error; |
| 455 | } |
| 456 | |
| 457 | /* Extract image hash from certificate */ |
| 458 | err = x509_get_crt_ext_data(&p, &sz, &cert, hash_oid); |
| 459 | if (err) { |
| 460 | ERROR("Cannot read hash from certificate\n"); |
| 461 | goto error; |
| 462 | } |
| 463 | |
Juan Castillo | f18daf7 | 2015-03-10 15:18:55 +0000 | [diff] [blame] | 464 | if (sz != SHA256_DER_BYTES) { |
| 465 | ERROR("Wrong image hash length: %lu\n", sz); |
| 466 | err = 1; |
| 467 | goto error; |
| 468 | } |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 469 | memcpy(sha, p, SHA256_DER_BYTES); |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 470 | |
| 471 | error: |
| 472 | x509_crt_free(&cert); |
| 473 | |
| 474 | return err; |
| 475 | } |
| 476 | #endif /* IMAGE_BL2 */ |
| 477 | |
| 478 | /* |
| 479 | * Calculate the hash of the image and check it against the hash extracted |
| 480 | * previously from the certificate |
| 481 | * |
| 482 | * Parameters: |
| 483 | * buf: buffer where image is loaded |
| 484 | * len: size of the image |
| 485 | * sha: matching hash (extracted from the image certificate) |
| 486 | * |
| 487 | * Return: 0 = match, Otherwise = mismatch |
| 488 | */ |
| 489 | static int check_bl_img(unsigned char *buf, size_t len, |
| 490 | const unsigned char *sha) |
| 491 | { |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 492 | asn1_buf md_oid, params; |
| 493 | md_type_t md_alg; |
| 494 | int err; |
| 495 | unsigned char *p = NULL; |
| 496 | const unsigned char *end = NULL; |
| 497 | size_t sz; |
| 498 | unsigned char img_sha[SHA256_BYTES]; |
| 499 | |
| 500 | /* |
| 501 | * Extract the image hash from the ASN.1 structure: |
| 502 | * |
| 503 | * DigestInfo ::= SEQUENCE { |
| 504 | * digestAlgorithm AlgorithmIdentifier, |
| 505 | * digest OCTET STRING |
| 506 | * } |
| 507 | */ |
| 508 | |
| 509 | p = (unsigned char *)sha; |
| 510 | end = sha + SHA256_DER_BYTES; |
| 511 | err = asn1_get_tag(&p, end, &sz, ASN1_CONSTRUCTED | ASN1_SEQUENCE); |
| 512 | if (err != 0) { |
| 513 | ERROR("Malformed image hash extension\n"); |
| 514 | goto error; |
| 515 | } |
| 516 | |
| 517 | err = asn1_get_alg(&p, end, &md_oid, ¶ms); |
| 518 | if (err != 0) { |
| 519 | ERROR("Malformed image hash algorithm\n"); |
| 520 | goto error; |
| 521 | } |
| 522 | |
| 523 | err = oid_get_md_alg(&md_oid, &md_alg); |
| 524 | if (err != 0) { |
| 525 | ERROR("Unknown image hash algorithm\n"); |
| 526 | goto error; |
| 527 | } |
| 528 | |
| 529 | /* Only SHA256 is supported */ |
| 530 | if (md_alg != POLARSSL_MD_SHA256) { |
| 531 | ERROR("Only SHA256 is supported as image hash algorithm\n"); |
| 532 | err = 1; |
| 533 | goto error; |
| 534 | } |
| 535 | |
| 536 | /* Get the hash */ |
| 537 | err = asn1_get_tag(&p, end, &sz, ASN1_OCTET_STRING); |
| 538 | if (err != 0) { |
| 539 | ERROR("Image hash not found in extension\n"); |
| 540 | goto error; |
| 541 | } |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 542 | |
| 543 | /* Calculate the hash of the image */ |
| 544 | sha256(buf, len, img_sha, 0); |
| 545 | |
| 546 | /* Match the hash with the one extracted from the certificate */ |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 547 | if (memcmp(img_sha, p, SHA256_BYTES)) { |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 548 | ERROR("Image hash mismatch\n"); |
| 549 | return 1; |
| 550 | } |
| 551 | |
Juan Castillo | ac40293 | 2015-03-05 14:30:00 +0000 | [diff] [blame] | 552 | error: |
| 553 | return err; |
Juan Castillo | 9c25a40 | 2015-01-13 12:21:04 +0000 | [diff] [blame] | 554 | } |
| 555 | |
| 556 | /* |
| 557 | * Object verification function |
| 558 | * |
| 559 | * The id parameter will indicate the expected format of the object |
| 560 | * (certificate, image, etc). |
| 561 | * |
| 562 | * Return: 0 = success, Otherwise = error |
| 563 | */ |
| 564 | static int polarssl_mod_verify(unsigned int id, uintptr_t obj, size_t len) |
| 565 | { |
| 566 | int ret; |
| 567 | |
| 568 | switch (id) { |
| 569 | #if IMAGE_BL1 |
| 570 | case AUTH_BL2_IMG_CERT: |
| 571 | ret = check_bl2_cert((unsigned char *)obj, len); |
| 572 | break; |
| 573 | case AUTH_BL2_IMG: |
| 574 | ret = check_bl_img((unsigned char *)obj, len, sha_bl2); |
| 575 | break; |
| 576 | #endif /* IMAGE_BL1 */ |
| 577 | |
| 578 | #if IMAGE_BL2 |
| 579 | case AUTH_TRUSTED_KEY_CERT: |
| 580 | ret = check_trusted_key_cert((unsigned char *)obj, len); |
| 581 | break; |
| 582 | case AUTH_BL30_KEY_CERT: |
| 583 | ret = check_bl3x_key_cert((unsigned char *)obj, len, |
| 584 | tz_world_pk, tz_world_pk_len, |
| 585 | content_pk, &content_pk_len, |
| 586 | BL30_CONTENT_CERT_PK_OID); |
| 587 | break; |
| 588 | case AUTH_BL31_KEY_CERT: |
| 589 | ret = check_bl3x_key_cert((unsigned char *)obj, len, |
| 590 | tz_world_pk, tz_world_pk_len, |
| 591 | content_pk, &content_pk_len, |
| 592 | BL31_CONTENT_CERT_PK_OID); |
| 593 | break; |
| 594 | case AUTH_BL32_KEY_CERT: |
| 595 | ret = check_bl3x_key_cert((unsigned char *)obj, len, |
| 596 | tz_world_pk, tz_world_pk_len, |
| 597 | content_pk, &content_pk_len, |
| 598 | BL32_CONTENT_CERT_PK_OID); |
| 599 | break; |
| 600 | case AUTH_BL33_KEY_CERT: |
| 601 | ret = check_bl3x_key_cert((unsigned char *)obj, len, |
| 602 | ntz_world_pk, ntz_world_pk_len, |
| 603 | content_pk, &content_pk_len, |
| 604 | BL33_CONTENT_CERT_PK_OID); |
| 605 | break; |
| 606 | case AUTH_BL30_IMG_CERT: |
| 607 | ret = check_bl3x_cert((unsigned char *)obj, len, |
| 608 | content_pk, content_pk_len, |
| 609 | BL30_HASH_OID, sha_bl30); |
| 610 | break; |
| 611 | case AUTH_BL31_IMG_CERT: |
| 612 | ret = check_bl3x_cert((unsigned char *)obj, len, |
| 613 | content_pk, content_pk_len, |
| 614 | BL31_HASH_OID, sha_bl31); |
| 615 | break; |
| 616 | case AUTH_BL32_IMG_CERT: |
| 617 | ret = check_bl3x_cert((unsigned char *)obj, len, |
| 618 | content_pk, content_pk_len, |
| 619 | BL32_HASH_OID, sha_bl32); |
| 620 | break; |
| 621 | case AUTH_BL33_IMG_CERT: |
| 622 | ret = check_bl3x_cert((unsigned char *)obj, len, |
| 623 | content_pk, content_pk_len, |
| 624 | BL33_HASH_OID, sha_bl33); |
| 625 | break; |
| 626 | case AUTH_BL30_IMG: |
| 627 | ret = check_bl_img((unsigned char *)obj, len, sha_bl30); |
| 628 | break; |
| 629 | case AUTH_BL31_IMG: |
| 630 | ret = check_bl_img((unsigned char *)obj, len, sha_bl31); |
| 631 | break; |
| 632 | case AUTH_BL32_IMG: |
| 633 | ret = check_bl_img((unsigned char *)obj, len, sha_bl32); |
| 634 | break; |
| 635 | case AUTH_BL33_IMG: |
| 636 | ret = check_bl_img((unsigned char *)obj, len, sha_bl33); |
| 637 | break; |
| 638 | #endif /* IMAGE_BL2 */ |
| 639 | default: |
| 640 | ret = -1; |
| 641 | break; |
| 642 | } |
| 643 | |
| 644 | return ret; |
| 645 | } |
| 646 | |
| 647 | /* |
| 648 | * Module initialization function |
| 649 | * |
| 650 | * Return: 0 = success, Otherwise = error |
| 651 | */ |
| 652 | static int polarssl_mod_init(void) |
| 653 | { |
| 654 | /* Initialize the PolarSSL heap */ |
| 655 | return memory_buffer_alloc_init(heap, POLARSSL_HEAP_SIZE); |
| 656 | } |
| 657 | |
| 658 | const auth_mod_t auth_mod = { |
| 659 | .name = "PolarSSL", |
| 660 | .init = polarssl_mod_init, |
| 661 | .verify = polarssl_mod_verify |
| 662 | }; |