Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 1 | /* |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 2 | * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 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 | /* |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 32 | * X509 parser based on mbed TLS |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 33 | * |
| 34 | * This module implements functions to check the integrity of a X509v3 |
| 35 | * certificate ASN.1 structure and extract authentication parameters from the |
| 36 | * extensions field, such as an image hash or a public key. |
| 37 | */ |
| 38 | |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 39 | #include <arch_helpers.h> |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 40 | #include <assert.h> |
| 41 | #include <img_parser_mod.h> |
| 42 | #include <mbedtls_common.h> |
| 43 | #include <stddef.h> |
| 44 | #include <stdint.h> |
| 45 | #include <string.h> |
| 46 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 47 | /* mbed TLS headers */ |
| 48 | #include <mbedtls/asn1.h> |
| 49 | #include <mbedtls/oid.h> |
| 50 | #include <mbedtls/platform.h> |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 51 | |
| 52 | /* Maximum OID string length ("a.b.c.d.e.f ...") */ |
| 53 | #define MAX_OID_STR_LEN 64 |
| 54 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 55 | #define LIB_NAME "mbed TLS X509v3" |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 56 | |
| 57 | /* Temporary variables to speed up the authentication parameters search. These |
| 58 | * variables are assigned once during the integrity check and used any time an |
| 59 | * authentication parameter is requested, so we do not have to parse the image |
| 60 | * again */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 61 | static mbedtls_asn1_buf tbs; |
| 62 | static mbedtls_asn1_buf v3_ext; |
| 63 | static mbedtls_asn1_buf pk; |
| 64 | static mbedtls_asn1_buf sig_alg; |
| 65 | static mbedtls_asn1_buf signature; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 66 | |
| 67 | /* |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 68 | * Clear all static temporary variables. |
| 69 | */ |
| 70 | static void clear_temp_vars(void) |
| 71 | { |
| 72 | #define ZERO_AND_CLEAN(x) \ |
| 73 | do { \ |
| 74 | memset(&x, 0, sizeof(x)); \ |
| 75 | clean_dcache_range((uintptr_t)&x, sizeof(x)); \ |
| 76 | } while (0); |
| 77 | |
| 78 | ZERO_AND_CLEAN(tbs) |
| 79 | ZERO_AND_CLEAN(v3_ext); |
| 80 | ZERO_AND_CLEAN(pk); |
| 81 | ZERO_AND_CLEAN(sig_alg); |
| 82 | ZERO_AND_CLEAN(signature); |
| 83 | |
| 84 | #undef ZERO_AND_CLEAN |
| 85 | } |
| 86 | |
| 87 | /* |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 88 | * Get X509v3 extension |
| 89 | * |
| 90 | * Global variable 'v3_ext' must point to the extensions region |
| 91 | * in the certificate. No need to check for errors since the image has passed |
| 92 | * the integrity check. |
| 93 | */ |
| 94 | static int get_ext(const char *oid, void **ext, unsigned int *ext_len) |
| 95 | { |
| 96 | int oid_len; |
| 97 | size_t len; |
| 98 | unsigned char *end_ext_data, *end_ext_octet; |
| 99 | unsigned char *p; |
| 100 | const unsigned char *end; |
| 101 | char oid_str[MAX_OID_STR_LEN]; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 102 | mbedtls_asn1_buf extn_oid; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 103 | int is_critical; |
| 104 | |
| 105 | assert(oid != NULL); |
| 106 | |
| 107 | p = v3_ext.p; |
| 108 | end = v3_ext.p + v3_ext.len; |
| 109 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 110 | mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 111 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 112 | |
| 113 | while (p < end) { |
| 114 | memset(&extn_oid, 0x0, sizeof(extn_oid)); |
| 115 | is_critical = 0; /* DEFAULT FALSE */ |
| 116 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 117 | mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 118 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 119 | end_ext_data = p + len; |
| 120 | |
| 121 | /* Get extension ID */ |
| 122 | extn_oid.tag = *p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 123 | mbedtls_asn1_get_tag(&p, end, &extn_oid.len, MBEDTLS_ASN1_OID); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 124 | extn_oid.p = p; |
| 125 | p += extn_oid.len; |
| 126 | |
| 127 | /* Get optional critical */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 128 | mbedtls_asn1_get_bool(&p, end_ext_data, &is_critical); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 129 | |
| 130 | /* Extension data */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 131 | mbedtls_asn1_get_tag(&p, end_ext_data, &len, |
| 132 | MBEDTLS_ASN1_OCTET_STRING); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 133 | end_ext_octet = p + len; |
| 134 | |
| 135 | /* Detect requested extension */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 136 | oid_len = mbedtls_oid_get_numeric_string(oid_str, |
| 137 | MAX_OID_STR_LEN, |
| 138 | &extn_oid); |
| 139 | if (oid_len == MBEDTLS_ERR_OID_BUF_TOO_SMALL) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 140 | return IMG_PARSER_ERR; |
| 141 | } |
| 142 | if ((oid_len == strlen(oid_str)) && !strcmp(oid, oid_str)) { |
| 143 | *ext = (void *)p; |
| 144 | *ext_len = (unsigned int)len; |
| 145 | return IMG_PARSER_OK; |
| 146 | } |
| 147 | |
| 148 | /* Next */ |
| 149 | p = end_ext_octet; |
| 150 | } |
| 151 | |
| 152 | return IMG_PARSER_ERR_NOT_FOUND; |
| 153 | } |
| 154 | |
| 155 | |
| 156 | /* |
| 157 | * Check the integrity of the certificate ASN.1 structure. |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 158 | * |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 159 | * Extract the relevant data that will be used later during authentication. |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 160 | * |
| 161 | * This function doesn't clear the static variables located on the top of this |
| 162 | * file in case of an error. It is only called from check_integrity(), which |
| 163 | * performs the cleanup if necessary. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 164 | */ |
| 165 | static int cert_parse(void *img, unsigned int img_len) |
| 166 | { |
| 167 | int ret, is_critical; |
| 168 | size_t len; |
| 169 | unsigned char *p, *end, *crt_end; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 170 | mbedtls_asn1_buf sig_alg1, sig_alg2; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 171 | |
| 172 | p = (unsigned char *)img; |
| 173 | len = img_len; |
| 174 | end = p + len; |
| 175 | |
| 176 | /* |
| 177 | * Certificate ::= SEQUENCE { |
| 178 | * tbsCertificate TBSCertificate, |
| 179 | * signatureAlgorithm AlgorithmIdentifier, |
| 180 | * signatureValue BIT STRING } |
| 181 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 182 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 183 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 184 | if (ret != 0) { |
| 185 | return IMG_PARSER_ERR_FORMAT; |
| 186 | } |
| 187 | |
| 188 | if (len > (size_t)(end - p)) { |
| 189 | return IMG_PARSER_ERR_FORMAT; |
| 190 | } |
| 191 | crt_end = p + len; |
| 192 | |
| 193 | /* |
| 194 | * TBSCertificate ::= SEQUENCE { |
| 195 | */ |
| 196 | tbs.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 197 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 198 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 199 | if (ret != 0) { |
| 200 | return IMG_PARSER_ERR_FORMAT; |
| 201 | } |
| 202 | end = p + len; |
| 203 | tbs.len = end - tbs.p; |
| 204 | |
| 205 | /* |
| 206 | * Version ::= INTEGER { v1(0), v2(1), v3(2) } |
| 207 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 208 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 209 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 210 | MBEDTLS_ASN1_CONSTRUCTED | 0); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 211 | if (ret != 0) { |
| 212 | return IMG_PARSER_ERR_FORMAT; |
| 213 | } |
| 214 | p += len; |
| 215 | |
| 216 | /* |
| 217 | * CertificateSerialNumber ::= INTEGER |
| 218 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 219 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 220 | if (ret != 0) { |
| 221 | return IMG_PARSER_ERR_FORMAT; |
| 222 | } |
| 223 | p += len; |
| 224 | |
| 225 | /* |
| 226 | * signature AlgorithmIdentifier |
| 227 | */ |
| 228 | sig_alg1.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 229 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 230 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 231 | if (ret != 0) { |
| 232 | return IMG_PARSER_ERR_FORMAT; |
| 233 | } |
| 234 | if ((end - p) < 1) { |
| 235 | return IMG_PARSER_ERR_FORMAT; |
| 236 | } |
| 237 | sig_alg1.len = (p + len) - sig_alg1.p; |
| 238 | p += len; |
| 239 | |
| 240 | /* |
| 241 | * issuer Name |
| 242 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 243 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 244 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 245 | if (ret != 0) { |
| 246 | return IMG_PARSER_ERR_FORMAT; |
| 247 | } |
| 248 | p += len; |
| 249 | |
| 250 | /* |
| 251 | * Validity ::= SEQUENCE { |
| 252 | * notBefore Time, |
| 253 | * notAfter Time } |
| 254 | * |
| 255 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 256 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 257 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 258 | if (ret != 0) { |
| 259 | return IMG_PARSER_ERR_FORMAT; |
| 260 | } |
| 261 | p += len; |
| 262 | |
| 263 | /* |
| 264 | * subject Name |
| 265 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 266 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 267 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 268 | if (ret != 0) { |
| 269 | return IMG_PARSER_ERR_FORMAT; |
| 270 | } |
| 271 | p += len; |
| 272 | |
| 273 | /* |
| 274 | * SubjectPublicKeyInfo |
| 275 | */ |
| 276 | pk.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 277 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 278 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 279 | if (ret != 0) { |
| 280 | return IMG_PARSER_ERR_FORMAT; |
| 281 | } |
| 282 | pk.len = (p + len) - pk.p; |
| 283 | p += len; |
| 284 | |
| 285 | /* |
| 286 | * issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL, |
| 287 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 288 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 289 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 290 | MBEDTLS_ASN1_CONSTRUCTED | 1); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 291 | if (ret != 0) { |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 292 | if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 293 | return IMG_PARSER_ERR_FORMAT; |
| 294 | } |
| 295 | } else { |
| 296 | p += len; |
| 297 | } |
| 298 | |
| 299 | /* |
| 300 | * subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL, |
| 301 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 302 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 303 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 304 | MBEDTLS_ASN1_CONSTRUCTED | 2); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 305 | if (ret != 0) { |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 306 | if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 307 | return IMG_PARSER_ERR_FORMAT; |
| 308 | } |
| 309 | } else { |
| 310 | p += len; |
| 311 | } |
| 312 | |
| 313 | /* |
| 314 | * extensions [3] EXPLICIT Extensions OPTIONAL |
| 315 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 316 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 317 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 318 | MBEDTLS_ASN1_CONSTRUCTED | 3); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 319 | if (ret != 0) { |
| 320 | return IMG_PARSER_ERR_FORMAT; |
| 321 | } |
| 322 | |
| 323 | /* |
| 324 | * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension |
| 325 | */ |
| 326 | v3_ext.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 327 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 328 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 329 | if (ret != 0) { |
| 330 | return IMG_PARSER_ERR_FORMAT; |
| 331 | } |
| 332 | v3_ext.len = (p + len) - v3_ext.p; |
| 333 | |
| 334 | /* |
| 335 | * Check extensions integrity |
| 336 | */ |
| 337 | while (p < end) { |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 338 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 339 | MBEDTLS_ASN1_CONSTRUCTED | |
| 340 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 341 | if (ret != 0) { |
| 342 | return IMG_PARSER_ERR_FORMAT; |
| 343 | } |
| 344 | |
| 345 | /* Get extension ID */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 346 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OID); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 347 | if (ret != 0) { |
| 348 | return IMG_PARSER_ERR_FORMAT; |
| 349 | } |
| 350 | p += len; |
| 351 | |
| 352 | /* Get optional critical */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 353 | ret = mbedtls_asn1_get_bool(&p, end, &is_critical); |
| 354 | if ((ret != 0) && (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG)) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 355 | return IMG_PARSER_ERR_FORMAT; |
| 356 | } |
| 357 | |
| 358 | /* Data should be octet string type */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 359 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 360 | MBEDTLS_ASN1_OCTET_STRING); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 361 | if (ret != 0) { |
| 362 | return IMG_PARSER_ERR_FORMAT; |
| 363 | } |
| 364 | p += len; |
| 365 | } |
| 366 | |
| 367 | if (p != end) { |
| 368 | return IMG_PARSER_ERR_FORMAT; |
| 369 | } |
| 370 | |
| 371 | end = crt_end; |
| 372 | |
| 373 | /* |
| 374 | * } |
| 375 | * -- end of TBSCertificate |
| 376 | * |
| 377 | * signatureAlgorithm AlgorithmIdentifier |
| 378 | */ |
| 379 | sig_alg2.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 380 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 381 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 382 | if (ret != 0) { |
| 383 | return IMG_PARSER_ERR_FORMAT; |
| 384 | } |
| 385 | if ((end - p) < 1) { |
| 386 | return IMG_PARSER_ERR_FORMAT; |
| 387 | } |
| 388 | sig_alg2.len = (p + len) - sig_alg2.p; |
| 389 | p += len; |
| 390 | |
| 391 | /* Compare both signature algorithms */ |
| 392 | if (sig_alg1.len != sig_alg2.len) { |
| 393 | return IMG_PARSER_ERR_FORMAT; |
| 394 | } |
Antonio Nino Diaz | 6adeeda | 2017-01-13 13:53:32 +0000 | [diff] [blame] | 395 | if (0 != timingsafe_bcmp(sig_alg1.p, sig_alg2.p, sig_alg1.len)) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 396 | return IMG_PARSER_ERR_FORMAT; |
| 397 | } |
| 398 | memcpy(&sig_alg, &sig_alg1, sizeof(sig_alg)); |
| 399 | |
| 400 | /* |
| 401 | * signatureValue BIT STRING |
| 402 | */ |
| 403 | signature.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 404 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_BIT_STRING); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 405 | if (ret != 0) { |
| 406 | return IMG_PARSER_ERR_FORMAT; |
| 407 | } |
| 408 | signature.len = (p + len) - signature.p; |
| 409 | p += len; |
| 410 | |
| 411 | /* Check certificate length */ |
| 412 | if (p != end) { |
| 413 | return IMG_PARSER_ERR_FORMAT; |
| 414 | } |
| 415 | |
| 416 | return IMG_PARSER_OK; |
| 417 | } |
| 418 | |
| 419 | |
| 420 | /* Exported functions */ |
| 421 | |
| 422 | static void init(void) |
| 423 | { |
| 424 | mbedtls_init(); |
| 425 | } |
| 426 | |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 427 | /* |
| 428 | * Wrapper for cert_parse() that clears the static variables used by it in case |
| 429 | * of an error. |
| 430 | */ |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 431 | static int check_integrity(void *img, unsigned int img_len) |
| 432 | { |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 433 | int rc = cert_parse(img, img_len); |
| 434 | |
| 435 | if (rc != IMG_PARSER_OK) |
| 436 | clear_temp_vars(); |
| 437 | |
| 438 | return rc; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 439 | } |
| 440 | |
| 441 | /* |
| 442 | * Extract an authentication parameter from an X509v3 certificate |
Juan Castillo | bfb7fa6 | 2016-01-22 11:05:57 +0000 | [diff] [blame] | 443 | * |
| 444 | * This function returns a pointer to the extracted data and its length. |
| 445 | * Depending on the type of parameter, a pointer to the data stored in the |
| 446 | * certificate may be returned (i.e. an octet string containing a hash). Other |
| 447 | * data may need to be copied and formatted (i.e. integers). In the later case, |
| 448 | * a buffer of the correct type needs to be statically allocated, filled and |
| 449 | * returned. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 450 | */ |
| 451 | static int get_auth_param(const auth_param_type_desc_t *type_desc, |
| 452 | void *img, unsigned int img_len, |
| 453 | void **param, unsigned int *param_len) |
| 454 | { |
| 455 | int rc = IMG_PARSER_OK; |
| 456 | |
| 457 | /* We do not use img because the check_integrity function has already |
| 458 | * extracted the relevant data (v3_ext, pk, sig_alg, etc) */ |
| 459 | |
| 460 | switch (type_desc->type) { |
| 461 | case AUTH_PARAM_RAW_DATA: |
| 462 | /* Data to be signed */ |
| 463 | *param = (void *)tbs.p; |
| 464 | *param_len = (unsigned int)tbs.len; |
| 465 | break; |
| 466 | case AUTH_PARAM_HASH: |
Juan Castillo | bfb7fa6 | 2016-01-22 11:05:57 +0000 | [diff] [blame] | 467 | case AUTH_PARAM_NV_CTR: |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 468 | /* All these parameters are included as X509v3 extensions */ |
| 469 | rc = get_ext(type_desc->cookie, param, param_len); |
| 470 | break; |
| 471 | case AUTH_PARAM_PUB_KEY: |
| 472 | if (type_desc->cookie != 0) { |
| 473 | /* Get public key from extension */ |
| 474 | rc = get_ext(type_desc->cookie, param, param_len); |
| 475 | } else { |
| 476 | /* Get the subject public key */ |
| 477 | *param = (void *)pk.p; |
| 478 | *param_len = (unsigned int)pk.len; |
| 479 | } |
| 480 | break; |
| 481 | case AUTH_PARAM_SIG_ALG: |
| 482 | /* Get the certificate signature algorithm */ |
| 483 | *param = (void *)sig_alg.p; |
| 484 | *param_len = (unsigned int)sig_alg.len; |
| 485 | break; |
| 486 | case AUTH_PARAM_SIG: |
| 487 | /* Get the certificate signature */ |
| 488 | *param = (void *)signature.p; |
| 489 | *param_len = (unsigned int)signature.len; |
| 490 | break; |
| 491 | default: |
| 492 | rc = IMG_PARSER_ERR_NOT_FOUND; |
| 493 | break; |
| 494 | } |
| 495 | |
| 496 | return rc; |
| 497 | } |
| 498 | |
| 499 | REGISTER_IMG_PARSER_LIB(IMG_CERT, LIB_NAME, init, \ |
| 500 | check_integrity, get_auth_param); |