Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 1 | /* |
Nicolas Toromanoff | 2d817a3 | 2020-12-23 16:01:25 +0100 | [diff] [blame] | 2 | * Copyright (c) 2015-2022, ARM Limited and Contributors. All rights reserved. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 3 | * |
dp-arm | fa3cf0b | 2017-05-03 09:38:09 +0100 | [diff] [blame] | 4 | * SPDX-License-Identifier: BSD-3-Clause |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 5 | */ |
| 6 | |
| 7 | /* |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 8 | * X509 parser based on mbed TLS |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 9 | * |
| 10 | * This module implements functions to check the integrity of a X509v3 |
| 11 | * certificate ASN.1 structure and extract authentication parameters from the |
| 12 | * extensions field, such as an image hash or a public key. |
| 13 | */ |
| 14 | |
| 15 | #include <assert.h> |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 16 | #include <stddef.h> |
| 17 | #include <stdint.h> |
| 18 | #include <string.h> |
| 19 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 20 | /* mbed TLS headers */ |
| 21 | #include <mbedtls/asn1.h> |
| 22 | #include <mbedtls/oid.h> |
| 23 | #include <mbedtls/platform.h> |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 24 | |
Antonio Nino Diaz | e0f9063 | 2018-12-14 00:18:21 +0000 | [diff] [blame] | 25 | #include <arch_helpers.h> |
| 26 | #include <drivers/auth/img_parser_mod.h> |
| 27 | #include <drivers/auth/mbedtls/mbedtls_common.h> |
| 28 | #include <lib/utils.h> |
| 29 | |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 30 | /* Maximum OID string length ("a.b.c.d.e.f ...") */ |
| 31 | #define MAX_OID_STR_LEN 64 |
| 32 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 33 | #define LIB_NAME "mbed TLS X509v3" |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 34 | |
| 35 | /* Temporary variables to speed up the authentication parameters search. These |
| 36 | * variables are assigned once during the integrity check and used any time an |
| 37 | * authentication parameter is requested, so we do not have to parse the image |
| 38 | * again */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 39 | static mbedtls_asn1_buf tbs; |
| 40 | static mbedtls_asn1_buf v3_ext; |
| 41 | static mbedtls_asn1_buf pk; |
| 42 | static mbedtls_asn1_buf sig_alg; |
| 43 | static mbedtls_asn1_buf signature; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 44 | |
| 45 | /* |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 46 | * Clear all static temporary variables. |
| 47 | */ |
| 48 | static void clear_temp_vars(void) |
| 49 | { |
| 50 | #define ZERO_AND_CLEAN(x) \ |
| 51 | do { \ |
Douglas Raillard | a8954fc | 2017-01-26 15:54:44 +0000 | [diff] [blame] | 52 | zeromem(&x, sizeof(x)); \ |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 53 | clean_dcache_range((uintptr_t)&x, sizeof(x)); \ |
| 54 | } while (0); |
| 55 | |
| 56 | ZERO_AND_CLEAN(tbs) |
| 57 | ZERO_AND_CLEAN(v3_ext); |
| 58 | ZERO_AND_CLEAN(pk); |
| 59 | ZERO_AND_CLEAN(sig_alg); |
| 60 | ZERO_AND_CLEAN(signature); |
| 61 | |
| 62 | #undef ZERO_AND_CLEAN |
| 63 | } |
| 64 | |
| 65 | /* |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 66 | * Get X509v3 extension |
| 67 | * |
| 68 | * Global variable 'v3_ext' must point to the extensions region |
| 69 | * in the certificate. No need to check for errors since the image has passed |
| 70 | * the integrity check. |
| 71 | */ |
| 72 | static int get_ext(const char *oid, void **ext, unsigned int *ext_len) |
| 73 | { |
| 74 | int oid_len; |
| 75 | size_t len; |
| 76 | unsigned char *end_ext_data, *end_ext_octet; |
| 77 | unsigned char *p; |
| 78 | const unsigned char *end; |
| 79 | char oid_str[MAX_OID_STR_LEN]; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 80 | mbedtls_asn1_buf extn_oid; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 81 | int is_critical; |
| 82 | |
| 83 | assert(oid != NULL); |
| 84 | |
| 85 | p = v3_ext.p; |
| 86 | end = v3_ext.p + v3_ext.len; |
| 87 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 88 | mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 89 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 90 | |
| 91 | while (p < end) { |
Douglas Raillard | a8954fc | 2017-01-26 15:54:44 +0000 | [diff] [blame] | 92 | zeromem(&extn_oid, sizeof(extn_oid)); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 93 | is_critical = 0; /* DEFAULT FALSE */ |
| 94 | |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 95 | mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 96 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 97 | end_ext_data = p + len; |
| 98 | |
| 99 | /* Get extension ID */ |
| 100 | extn_oid.tag = *p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 101 | mbedtls_asn1_get_tag(&p, end, &extn_oid.len, MBEDTLS_ASN1_OID); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 102 | extn_oid.p = p; |
| 103 | p += extn_oid.len; |
| 104 | |
| 105 | /* Get optional critical */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 106 | mbedtls_asn1_get_bool(&p, end_ext_data, &is_critical); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 107 | |
| 108 | /* Extension data */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 109 | mbedtls_asn1_get_tag(&p, end_ext_data, &len, |
| 110 | MBEDTLS_ASN1_OCTET_STRING); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 111 | end_ext_octet = p + len; |
| 112 | |
| 113 | /* Detect requested extension */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 114 | oid_len = mbedtls_oid_get_numeric_string(oid_str, |
| 115 | MAX_OID_STR_LEN, |
| 116 | &extn_oid); |
Nicolas Toromanoff | 2d817a3 | 2020-12-23 16:01:25 +0100 | [diff] [blame] | 117 | if ((oid_len == MBEDTLS_ERR_OID_BUF_TOO_SMALL) || (oid_len < 0)) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 118 | return IMG_PARSER_ERR; |
| 119 | } |
Nicolas Toromanoff | 2d817a3 | 2020-12-23 16:01:25 +0100 | [diff] [blame] | 120 | if (((size_t)oid_len == strlen(oid_str)) && !strcmp(oid, oid_str)) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 121 | *ext = (void *)p; |
| 122 | *ext_len = (unsigned int)len; |
| 123 | return IMG_PARSER_OK; |
| 124 | } |
| 125 | |
| 126 | /* Next */ |
| 127 | p = end_ext_octet; |
| 128 | } |
| 129 | |
| 130 | return IMG_PARSER_ERR_NOT_FOUND; |
| 131 | } |
| 132 | |
| 133 | |
| 134 | /* |
| 135 | * Check the integrity of the certificate ASN.1 structure. |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 136 | * |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 137 | * Extract the relevant data that will be used later during authentication. |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 138 | * |
| 139 | * This function doesn't clear the static variables located on the top of this |
| 140 | * file in case of an error. It is only called from check_integrity(), which |
| 141 | * performs the cleanup if necessary. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 142 | */ |
| 143 | static int cert_parse(void *img, unsigned int img_len) |
| 144 | { |
| 145 | int ret, is_critical; |
| 146 | size_t len; |
Demi Marie Obenour | b1342a2 | 2022-12-08 15:24:18 -0500 | [diff] [blame] | 147 | unsigned char *p, *end, *crt_end, *pk_end; |
Demi Marie Obenour | 139b84c | 2022-12-08 15:24:23 -0500 | [diff] [blame^] | 148 | mbedtls_asn1_buf sig_alg1; |
Demi Marie Obenour | 83737b7 | 2022-12-08 15:23:50 -0500 | [diff] [blame] | 149 | /* |
| 150 | * The unique ASN.1 DER encoding of [0] EXPLICIT INTEGER { v3(2} }. |
| 151 | */ |
| 152 | static const char v3[] = { |
| 153 | /* The outer CONTEXT SPECIFIC 0 tag */ |
| 154 | MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC | 0, |
| 155 | /* The number bytes used to encode the inner INTEGER */ |
| 156 | 3, |
| 157 | /* The tag of the inner INTEGER */ |
| 158 | MBEDTLS_ASN1_INTEGER, |
| 159 | /* The number of bytes needed to represent 2 */ |
| 160 | 1, |
| 161 | /* The actual value 2 */ |
| 162 | 2, |
| 163 | }; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 164 | |
| 165 | p = (unsigned char *)img; |
| 166 | len = img_len; |
| 167 | end = p + len; |
| 168 | |
| 169 | /* |
| 170 | * Certificate ::= SEQUENCE { |
| 171 | * tbsCertificate TBSCertificate, |
| 172 | * signatureAlgorithm AlgorithmIdentifier, |
| 173 | * signatureValue BIT STRING } |
| 174 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 175 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 176 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 177 | if (ret != 0) { |
| 178 | return IMG_PARSER_ERR_FORMAT; |
| 179 | } |
| 180 | |
| 181 | if (len > (size_t)(end - p)) { |
| 182 | return IMG_PARSER_ERR_FORMAT; |
| 183 | } |
| 184 | crt_end = p + len; |
| 185 | |
| 186 | /* |
| 187 | * TBSCertificate ::= SEQUENCE { |
| 188 | */ |
| 189 | tbs.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 190 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 191 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 192 | if (ret != 0) { |
| 193 | return IMG_PARSER_ERR_FORMAT; |
| 194 | } |
| 195 | end = p + len; |
| 196 | tbs.len = end - tbs.p; |
| 197 | |
| 198 | /* |
Demi Marie Obenour | 83737b7 | 2022-12-08 15:23:50 -0500 | [diff] [blame] | 199 | * Version ::= [0] EXPLICIT INTEGER { v1(0), v2(1), v3(2) } |
| 200 | * -- only v3 accepted |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 201 | */ |
Demi Marie Obenour | 83737b7 | 2022-12-08 15:23:50 -0500 | [diff] [blame] | 202 | if (((end - p) <= (ptrdiff_t)sizeof(v3)) || |
| 203 | (memcmp(p, v3, sizeof(v3)) != 0)) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 204 | return IMG_PARSER_ERR_FORMAT; |
| 205 | } |
Demi Marie Obenour | 83737b7 | 2022-12-08 15:23:50 -0500 | [diff] [blame] | 206 | p += sizeof(v3); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 207 | |
| 208 | /* |
| 209 | * CertificateSerialNumber ::= INTEGER |
| 210 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 211 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 212 | if (ret != 0) { |
| 213 | return IMG_PARSER_ERR_FORMAT; |
| 214 | } |
| 215 | p += len; |
| 216 | |
| 217 | /* |
| 218 | * signature AlgorithmIdentifier |
| 219 | */ |
| 220 | sig_alg1.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 221 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 222 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 223 | if (ret != 0) { |
| 224 | return IMG_PARSER_ERR_FORMAT; |
| 225 | } |
| 226 | if ((end - p) < 1) { |
| 227 | return IMG_PARSER_ERR_FORMAT; |
| 228 | } |
| 229 | sig_alg1.len = (p + len) - sig_alg1.p; |
| 230 | p += len; |
| 231 | |
| 232 | /* |
| 233 | * issuer Name |
| 234 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 235 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 236 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 237 | if (ret != 0) { |
| 238 | return IMG_PARSER_ERR_FORMAT; |
| 239 | } |
| 240 | p += len; |
| 241 | |
| 242 | /* |
| 243 | * Validity ::= SEQUENCE { |
| 244 | * notBefore Time, |
| 245 | * notAfter Time } |
| 246 | * |
| 247 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 248 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 249 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 250 | if (ret != 0) { |
| 251 | return IMG_PARSER_ERR_FORMAT; |
| 252 | } |
| 253 | p += len; |
| 254 | |
| 255 | /* |
| 256 | * subject Name |
| 257 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 258 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 259 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 260 | if (ret != 0) { |
| 261 | return IMG_PARSER_ERR_FORMAT; |
| 262 | } |
| 263 | p += len; |
| 264 | |
| 265 | /* |
| 266 | * SubjectPublicKeyInfo |
| 267 | */ |
| 268 | pk.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 269 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 270 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 271 | if (ret != 0) { |
| 272 | return IMG_PARSER_ERR_FORMAT; |
| 273 | } |
Demi Marie Obenour | b1342a2 | 2022-12-08 15:24:18 -0500 | [diff] [blame] | 274 | pk_end = p + len; |
| 275 | pk.len = pk_end - pk.p; |
| 276 | |
| 277 | ret = mbedtls_asn1_get_tag(&p, pk_end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 278 | MBEDTLS_ASN1_SEQUENCE); |
| 279 | if (ret != 0) { |
| 280 | return IMG_PARSER_ERR_FORMAT; |
| 281 | } |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 282 | p += len; |
| 283 | |
Demi Marie Obenour | b1342a2 | 2022-12-08 15:24:18 -0500 | [diff] [blame] | 284 | ret = mbedtls_asn1_get_tag(&p, pk_end, &len, MBEDTLS_ASN1_BIT_STRING); |
| 285 | if ((ret != 0) || (p + len != pk_end)) { |
| 286 | return IMG_PARSER_ERR_FORMAT; |
| 287 | } |
| 288 | p = pk_end; |
| 289 | |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 290 | /* |
| 291 | * issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL, |
| 292 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 293 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 294 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 295 | MBEDTLS_ASN1_CONSTRUCTED | 1); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 296 | if (ret != 0) { |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 297 | if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 298 | return IMG_PARSER_ERR_FORMAT; |
| 299 | } |
| 300 | } else { |
| 301 | p += len; |
| 302 | } |
| 303 | |
| 304 | /* |
| 305 | * subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL, |
| 306 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 307 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 308 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 309 | MBEDTLS_ASN1_CONSTRUCTED | 2); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 310 | if (ret != 0) { |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 311 | if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 312 | return IMG_PARSER_ERR_FORMAT; |
| 313 | } |
| 314 | } else { |
| 315 | p += len; |
| 316 | } |
| 317 | |
| 318 | /* |
| 319 | * extensions [3] EXPLICIT Extensions OPTIONAL |
Demi Marie Obenour | 47a8055 | 2022-12-08 15:23:58 -0500 | [diff] [blame] | 320 | * } |
| 321 | * |
| 322 | * X.509 and RFC5280 allow omitting the extensions entirely. |
| 323 | * However, in TF-A, a certificate with no extensions would |
| 324 | * always fail later on, as the extensions contain the |
| 325 | * information needed to authenticate the next stage in the |
| 326 | * boot chain. Furthermore, get_ext() assumes that the |
| 327 | * extensions have been parsed into v3_ext, and allowing |
| 328 | * there to be no extensions would pointlessly complicate |
| 329 | * the code. Therefore, just reject certificates without |
| 330 | * extensions. This is also why version 1 and 2 certificates |
| 331 | * are rejected above. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 332 | */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 333 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 334 | MBEDTLS_ASN1_CONTEXT_SPECIFIC | |
| 335 | MBEDTLS_ASN1_CONSTRUCTED | 3); |
Demi Marie Obenour | fa07d04 | 2022-12-08 15:23:56 -0500 | [diff] [blame] | 336 | if ((ret != 0) || (len != (size_t)(end - p))) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 337 | return IMG_PARSER_ERR_FORMAT; |
| 338 | } |
| 339 | |
| 340 | /* |
| 341 | * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension |
Demi Marie Obenour | fa07d04 | 2022-12-08 15:23:56 -0500 | [diff] [blame] | 342 | * -- must use all remaining bytes in TBSCertificate |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 343 | */ |
| 344 | v3_ext.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 345 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 346 | MBEDTLS_ASN1_SEQUENCE); |
Demi Marie Obenour | fa07d04 | 2022-12-08 15:23:56 -0500 | [diff] [blame] | 347 | if ((ret != 0) || (len != (size_t)(end - p))) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 348 | return IMG_PARSER_ERR_FORMAT; |
| 349 | } |
Demi Marie Obenour | fa07d04 | 2022-12-08 15:23:56 -0500 | [diff] [blame] | 350 | v3_ext.len = end - v3_ext.p; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 351 | |
| 352 | /* |
Demi Marie Obenour | 47a8055 | 2022-12-08 15:23:58 -0500 | [diff] [blame] | 353 | * Check extensions integrity. At least one extension is |
| 354 | * required: the ASN.1 specifies a minimum size of 1, and at |
| 355 | * least one extension is needed to authenticate the next stage |
| 356 | * in the boot chain. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 357 | */ |
Demi Marie Obenour | 47a8055 | 2022-12-08 15:23:58 -0500 | [diff] [blame] | 358 | do { |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 359 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 360 | MBEDTLS_ASN1_CONSTRUCTED | |
| 361 | MBEDTLS_ASN1_SEQUENCE); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 362 | if (ret != 0) { |
| 363 | return IMG_PARSER_ERR_FORMAT; |
| 364 | } |
| 365 | |
| 366 | /* Get extension ID */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 367 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OID); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 368 | if (ret != 0) { |
| 369 | return IMG_PARSER_ERR_FORMAT; |
| 370 | } |
| 371 | p += len; |
| 372 | |
| 373 | /* Get optional critical */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 374 | ret = mbedtls_asn1_get_bool(&p, end, &is_critical); |
| 375 | if ((ret != 0) && (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG)) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 376 | return IMG_PARSER_ERR_FORMAT; |
| 377 | } |
| 378 | |
| 379 | /* Data should be octet string type */ |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 380 | ret = mbedtls_asn1_get_tag(&p, end, &len, |
| 381 | MBEDTLS_ASN1_OCTET_STRING); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 382 | if (ret != 0) { |
| 383 | return IMG_PARSER_ERR_FORMAT; |
| 384 | } |
| 385 | p += len; |
Demi Marie Obenour | 47a8055 | 2022-12-08 15:23:58 -0500 | [diff] [blame] | 386 | } while (p < end); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 387 | |
| 388 | if (p != end) { |
| 389 | return IMG_PARSER_ERR_FORMAT; |
| 390 | } |
| 391 | |
| 392 | end = crt_end; |
| 393 | |
| 394 | /* |
| 395 | * } |
| 396 | * -- end of TBSCertificate |
| 397 | * |
| 398 | * signatureAlgorithm AlgorithmIdentifier |
Demi Marie Obenour | 139b84c | 2022-12-08 15:24:23 -0500 | [diff] [blame^] | 399 | * -- Does not need to be parsed. Ensuring it is bitwise |
| 400 | * -- identical (including the tag!) with the first signature |
| 401 | * -- algorithm is sufficient. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 402 | */ |
Demi Marie Obenour | 139b84c | 2022-12-08 15:24:23 -0500 | [diff] [blame^] | 403 | if ((sig_alg1.len >= (size_t)(end - p)) || |
| 404 | (0 != memcmp(sig_alg1.p, p, sig_alg1.len))) { |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 405 | return IMG_PARSER_ERR_FORMAT; |
| 406 | } |
Demi Marie Obenour | 139b84c | 2022-12-08 15:24:23 -0500 | [diff] [blame^] | 407 | p += sig_alg1.len; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 408 | memcpy(&sig_alg, &sig_alg1, sizeof(sig_alg)); |
| 409 | |
| 410 | /* |
| 411 | * signatureValue BIT STRING |
| 412 | */ |
| 413 | signature.p = p; |
Juan Castillo | bae6b2a | 2015-11-05 09:24:53 +0000 | [diff] [blame] | 414 | ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_BIT_STRING); |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 415 | if (ret != 0) { |
| 416 | return IMG_PARSER_ERR_FORMAT; |
| 417 | } |
| 418 | signature.len = (p + len) - signature.p; |
| 419 | p += len; |
| 420 | |
| 421 | /* Check certificate length */ |
| 422 | if (p != end) { |
| 423 | return IMG_PARSER_ERR_FORMAT; |
| 424 | } |
| 425 | |
| 426 | return IMG_PARSER_OK; |
| 427 | } |
| 428 | |
| 429 | |
| 430 | /* Exported functions */ |
| 431 | |
| 432 | static void init(void) |
| 433 | { |
| 434 | mbedtls_init(); |
| 435 | } |
| 436 | |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 437 | /* |
| 438 | * Wrapper for cert_parse() that clears the static variables used by it in case |
| 439 | * of an error. |
| 440 | */ |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 441 | static int check_integrity(void *img, unsigned int img_len) |
| 442 | { |
Antonio Nino Diaz | 30eb967 | 2017-01-13 15:03:19 +0000 | [diff] [blame] | 443 | int rc = cert_parse(img, img_len); |
| 444 | |
| 445 | if (rc != IMG_PARSER_OK) |
| 446 | clear_temp_vars(); |
| 447 | |
| 448 | return rc; |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 449 | } |
| 450 | |
| 451 | /* |
| 452 | * Extract an authentication parameter from an X509v3 certificate |
Juan Castillo | bfb7fa6 | 2016-01-22 11:05:57 +0000 | [diff] [blame] | 453 | * |
| 454 | * This function returns a pointer to the extracted data and its length. |
| 455 | * Depending on the type of parameter, a pointer to the data stored in the |
| 456 | * certificate may be returned (i.e. an octet string containing a hash). Other |
| 457 | * data may need to be copied and formatted (i.e. integers). In the later case, |
| 458 | * a buffer of the correct type needs to be statically allocated, filled and |
| 459 | * returned. |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 460 | */ |
| 461 | static int get_auth_param(const auth_param_type_desc_t *type_desc, |
| 462 | void *img, unsigned int img_len, |
| 463 | void **param, unsigned int *param_len) |
| 464 | { |
| 465 | int rc = IMG_PARSER_OK; |
| 466 | |
| 467 | /* We do not use img because the check_integrity function has already |
| 468 | * extracted the relevant data (v3_ext, pk, sig_alg, etc) */ |
| 469 | |
| 470 | switch (type_desc->type) { |
| 471 | case AUTH_PARAM_RAW_DATA: |
| 472 | /* Data to be signed */ |
| 473 | *param = (void *)tbs.p; |
| 474 | *param_len = (unsigned int)tbs.len; |
| 475 | break; |
| 476 | case AUTH_PARAM_HASH: |
Juan Castillo | bfb7fa6 | 2016-01-22 11:05:57 +0000 | [diff] [blame] | 477 | case AUTH_PARAM_NV_CTR: |
Juan Castillo | a57a4d5 | 2015-04-02 15:44:20 +0100 | [diff] [blame] | 478 | /* All these parameters are included as X509v3 extensions */ |
| 479 | rc = get_ext(type_desc->cookie, param, param_len); |
| 480 | break; |
| 481 | case AUTH_PARAM_PUB_KEY: |
| 482 | if (type_desc->cookie != 0) { |
| 483 | /* Get public key from extension */ |
| 484 | rc = get_ext(type_desc->cookie, param, param_len); |
| 485 | } else { |
| 486 | /* Get the subject public key */ |
| 487 | *param = (void *)pk.p; |
| 488 | *param_len = (unsigned int)pk.len; |
| 489 | } |
| 490 | break; |
| 491 | case AUTH_PARAM_SIG_ALG: |
| 492 | /* Get the certificate signature algorithm */ |
| 493 | *param = (void *)sig_alg.p; |
| 494 | *param_len = (unsigned int)sig_alg.len; |
| 495 | break; |
| 496 | case AUTH_PARAM_SIG: |
| 497 | /* Get the certificate signature */ |
| 498 | *param = (void *)signature.p; |
| 499 | *param_len = (unsigned int)signature.len; |
| 500 | break; |
| 501 | default: |
| 502 | rc = IMG_PARSER_ERR_NOT_FOUND; |
| 503 | break; |
| 504 | } |
| 505 | |
| 506 | return rc; |
| 507 | } |
| 508 | |
| 509 | REGISTER_IMG_PARSER_LIB(IMG_CERT, LIB_NAME, init, \ |
| 510 | check_integrity, get_auth_param); |