Manish V Badarkhe | 8fbea62 | 2023-09-06 10:22:19 +0100 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2023, Arm Limited. All rights reserved. |
| 3 | * |
| 4 | * SPDX-License-Identifier: BSD-3-Clause |
| 5 | */ |
| 6 | |
| 7 | #include <assert.h> |
| 8 | #include <stddef.h> |
| 9 | #include <string.h> |
| 10 | |
| 11 | /* mbed TLS headers */ |
| 12 | #include <mbedtls/gcm.h> |
| 13 | #include <mbedtls/md.h> |
| 14 | #include <mbedtls/memory_buffer_alloc.h> |
| 15 | #include <mbedtls/oid.h> |
| 16 | #include <mbedtls/platform.h> |
| 17 | #include <mbedtls/version.h> |
| 18 | #include <mbedtls/x509.h> |
| 19 | |
| 20 | #include <common/debug.h> |
| 21 | #include <drivers/auth/crypto_mod.h> |
| 22 | #include <drivers/auth/mbedtls/mbedtls_common.h> |
| 23 | |
| 24 | #include <plat/common/platform.h> |
| 25 | |
| 26 | #define LIB_NAME "mbed TLS PSA" |
| 27 | |
| 28 | #if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| 29 | CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 30 | /* |
| 31 | * CRYPTO_MD_MAX_SIZE value is as per current stronger algorithm available |
| 32 | * so make sure that mbed TLS MD maximum size must be lesser than this. |
| 33 | */ |
| 34 | CASSERT(CRYPTO_MD_MAX_SIZE >= MBEDTLS_MD_MAX_SIZE, |
| 35 | assert_mbedtls_md_size_overflow); |
| 36 | |
| 37 | #endif /* |
| 38 | * CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| 39 | * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 40 | */ |
| 41 | |
| 42 | /* |
| 43 | * AlgorithmIdentifier ::= SEQUENCE { |
| 44 | * algorithm OBJECT IDENTIFIER, |
| 45 | * parameters ANY DEFINED BY algorithm OPTIONAL |
| 46 | * } |
| 47 | * |
| 48 | * SubjectPublicKeyInfo ::= SEQUENCE { |
| 49 | * algorithm AlgorithmIdentifier, |
| 50 | * subjectPublicKey BIT STRING |
| 51 | * } |
| 52 | * |
| 53 | * DigestInfo ::= SEQUENCE { |
| 54 | * digestAlgorithm AlgorithmIdentifier, |
| 55 | * digest OCTET STRING |
| 56 | * } |
| 57 | */ |
| 58 | |
| 59 | /* |
| 60 | * Initialize the library and export the descriptor |
| 61 | */ |
| 62 | static void init(void) |
| 63 | { |
| 64 | /* Initialize mbed TLS */ |
| 65 | mbedtls_init(); |
| 66 | } |
| 67 | |
| 68 | #if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ |
| 69 | CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 70 | /* |
| 71 | * Verify a signature. |
| 72 | * |
| 73 | * Parameters are passed using the DER encoding format following the ASN.1 |
| 74 | * structures detailed above. |
| 75 | */ |
| 76 | static int verify_signature(void *data_ptr, unsigned int data_len, |
| 77 | void *sig_ptr, unsigned int sig_len, |
| 78 | void *sig_alg, unsigned int sig_alg_len, |
| 79 | void *pk_ptr, unsigned int pk_len) |
| 80 | { |
| 81 | mbedtls_asn1_buf sig_oid, sig_params; |
| 82 | mbedtls_asn1_buf signature; |
| 83 | mbedtls_md_type_t md_alg; |
| 84 | mbedtls_pk_type_t pk_alg; |
| 85 | mbedtls_pk_context pk = {0}; |
| 86 | int rc; |
| 87 | void *sig_opts = NULL; |
| 88 | const mbedtls_md_info_t *md_info; |
| 89 | unsigned char *p, *end; |
| 90 | unsigned char hash[MBEDTLS_MD_MAX_SIZE]; |
| 91 | |
| 92 | /* Get pointers to signature OID and parameters */ |
| 93 | p = (unsigned char *)sig_alg; |
| 94 | end = (unsigned char *)(p + sig_alg_len); |
| 95 | rc = mbedtls_asn1_get_alg(&p, end, &sig_oid, &sig_params); |
| 96 | if (rc != 0) { |
| 97 | return CRYPTO_ERR_SIGNATURE; |
| 98 | } |
| 99 | |
| 100 | /* Get the actual signature algorithm (MD + PK) */ |
| 101 | rc = mbedtls_x509_get_sig_alg(&sig_oid, &sig_params, &md_alg, &pk_alg, &sig_opts); |
| 102 | if (rc != 0) { |
| 103 | return CRYPTO_ERR_SIGNATURE; |
| 104 | } |
| 105 | |
| 106 | /* Parse the public key */ |
| 107 | mbedtls_pk_init(&pk); |
| 108 | p = (unsigned char *)pk_ptr; |
| 109 | end = (unsigned char *)(p + pk_len); |
| 110 | rc = mbedtls_pk_parse_subpubkey(&p, end, &pk); |
| 111 | if (rc != 0) { |
| 112 | rc = CRYPTO_ERR_SIGNATURE; |
| 113 | goto end2; |
| 114 | } |
| 115 | |
| 116 | /* Get the signature (bitstring) */ |
| 117 | p = (unsigned char *)sig_ptr; |
| 118 | end = (unsigned char *)(p + sig_len); |
| 119 | signature.tag = *p; |
| 120 | rc = mbedtls_asn1_get_bitstring_null(&p, end, &signature.len); |
| 121 | if ((rc != 0) || ((size_t)(end - p) != signature.len)) { |
| 122 | rc = CRYPTO_ERR_SIGNATURE; |
| 123 | goto end1; |
| 124 | } |
| 125 | signature.p = p; |
| 126 | |
| 127 | /* Calculate the hash of the data */ |
| 128 | md_info = mbedtls_md_info_from_type(md_alg); |
| 129 | if (md_info == NULL) { |
| 130 | rc = CRYPTO_ERR_SIGNATURE; |
| 131 | goto end1; |
| 132 | } |
| 133 | p = (unsigned char *)data_ptr; |
| 134 | rc = mbedtls_md(md_info, p, data_len, hash); |
| 135 | if (rc != 0) { |
| 136 | rc = CRYPTO_ERR_SIGNATURE; |
| 137 | goto end1; |
| 138 | } |
| 139 | |
| 140 | /* Verify the signature */ |
| 141 | rc = mbedtls_pk_verify_ext(pk_alg, sig_opts, &pk, md_alg, hash, |
| 142 | mbedtls_md_get_size(md_info), |
| 143 | signature.p, signature.len); |
| 144 | if (rc != 0) { |
| 145 | rc = CRYPTO_ERR_SIGNATURE; |
| 146 | goto end1; |
| 147 | } |
| 148 | |
| 149 | /* Signature verification success */ |
| 150 | rc = CRYPTO_SUCCESS; |
| 151 | |
| 152 | end1: |
| 153 | mbedtls_pk_free(&pk); |
| 154 | end2: |
| 155 | mbedtls_free(sig_opts); |
| 156 | return rc; |
| 157 | } |
| 158 | |
| 159 | /* |
| 160 | * Match a hash |
| 161 | * |
| 162 | * Digest info is passed in DER format following the ASN.1 structure detailed |
| 163 | * above. |
| 164 | */ |
| 165 | static int verify_hash(void *data_ptr, unsigned int data_len, |
| 166 | void *digest_info_ptr, unsigned int digest_info_len) |
| 167 | { |
| 168 | mbedtls_asn1_buf hash_oid, params; |
| 169 | mbedtls_md_type_t md_alg; |
| 170 | const mbedtls_md_info_t *md_info; |
| 171 | unsigned char *p, *end, *hash; |
| 172 | unsigned char data_hash[MBEDTLS_MD_MAX_SIZE]; |
| 173 | size_t len; |
| 174 | int rc; |
| 175 | |
| 176 | /* |
| 177 | * Digest info should be an MBEDTLS_ASN1_SEQUENCE, but padding after |
| 178 | * it is allowed. This is necessary to support multiple hash |
| 179 | * algorithms. |
| 180 | */ |
| 181 | p = (unsigned char *)digest_info_ptr; |
| 182 | end = p + digest_info_len; |
| 183 | rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED | |
| 184 | MBEDTLS_ASN1_SEQUENCE); |
| 185 | if (rc != 0) { |
| 186 | return CRYPTO_ERR_HASH; |
| 187 | } |
| 188 | |
| 189 | end = p + len; |
| 190 | |
| 191 | /* Get the hash algorithm */ |
| 192 | rc = mbedtls_asn1_get_alg(&p, end, &hash_oid, ¶ms); |
| 193 | if (rc != 0) { |
| 194 | return CRYPTO_ERR_HASH; |
| 195 | } |
| 196 | |
| 197 | rc = mbedtls_oid_get_md_alg(&hash_oid, &md_alg); |
| 198 | if (rc != 0) { |
| 199 | return CRYPTO_ERR_HASH; |
| 200 | } |
| 201 | |
| 202 | md_info = mbedtls_md_info_from_type(md_alg); |
| 203 | if (md_info == NULL) { |
| 204 | return CRYPTO_ERR_HASH; |
| 205 | } |
| 206 | |
| 207 | /* Hash should be octet string type and consume all bytes */ |
| 208 | rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING); |
| 209 | if ((rc != 0) || ((size_t)(end - p) != len)) { |
| 210 | return CRYPTO_ERR_HASH; |
| 211 | } |
| 212 | |
| 213 | /* Length of hash must match the algorithm's size */ |
| 214 | if (len != mbedtls_md_get_size(md_info)) { |
| 215 | return CRYPTO_ERR_HASH; |
| 216 | } |
| 217 | hash = p; |
| 218 | |
| 219 | /* Calculate the hash of the data */ |
| 220 | p = (unsigned char *)data_ptr; |
| 221 | rc = mbedtls_md(md_info, p, data_len, data_hash); |
| 222 | if (rc != 0) { |
| 223 | return CRYPTO_ERR_HASH; |
| 224 | } |
| 225 | |
| 226 | /* Compare values */ |
| 227 | rc = memcmp(data_hash, hash, mbedtls_md_get_size(md_info)); |
| 228 | if (rc != 0) { |
| 229 | return CRYPTO_ERR_HASH; |
| 230 | } |
| 231 | |
| 232 | return CRYPTO_SUCCESS; |
| 233 | } |
| 234 | #endif /* |
| 235 | * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ |
| 236 | * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 237 | */ |
| 238 | |
| 239 | #if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| 240 | CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 241 | /* |
| 242 | * Map a generic crypto message digest algorithm to the corresponding macro used |
| 243 | * by Mbed TLS. |
| 244 | */ |
| 245 | static inline mbedtls_md_type_t md_type(enum crypto_md_algo algo) |
| 246 | { |
| 247 | switch (algo) { |
| 248 | case CRYPTO_MD_SHA512: |
| 249 | return MBEDTLS_MD_SHA512; |
| 250 | case CRYPTO_MD_SHA384: |
| 251 | return MBEDTLS_MD_SHA384; |
| 252 | case CRYPTO_MD_SHA256: |
| 253 | return MBEDTLS_MD_SHA256; |
| 254 | default: |
| 255 | /* Invalid hash algorithm. */ |
| 256 | return MBEDTLS_MD_NONE; |
| 257 | } |
| 258 | } |
| 259 | |
| 260 | /* |
| 261 | * Calculate a hash |
| 262 | * |
| 263 | * output points to the computed hash |
| 264 | */ |
| 265 | static int calc_hash(enum crypto_md_algo md_algo, void *data_ptr, |
| 266 | unsigned int data_len, |
| 267 | unsigned char output[CRYPTO_MD_MAX_SIZE]) |
| 268 | { |
| 269 | const mbedtls_md_info_t *md_info; |
| 270 | |
| 271 | md_info = mbedtls_md_info_from_type(md_type(md_algo)); |
| 272 | if (md_info == NULL) { |
| 273 | return CRYPTO_ERR_HASH; |
| 274 | } |
| 275 | |
| 276 | /* |
| 277 | * Calculate the hash of the data, it is safe to pass the |
| 278 | * 'output' hash buffer pointer considering its size is always |
| 279 | * bigger than or equal to MBEDTLS_MD_MAX_SIZE. |
| 280 | */ |
| 281 | return mbedtls_md(md_info, data_ptr, data_len, output); |
| 282 | } |
| 283 | #endif /* |
| 284 | * CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| 285 | * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 286 | */ |
| 287 | |
| 288 | #if TF_MBEDTLS_USE_AES_GCM |
| 289 | /* |
| 290 | * Stack based buffer allocation for decryption operation. It could |
| 291 | * be configured to balance stack usage vs execution speed. |
| 292 | */ |
| 293 | #define DEC_OP_BUF_SIZE 128 |
| 294 | |
| 295 | static int aes_gcm_decrypt(void *data_ptr, size_t len, const void *key, |
| 296 | unsigned int key_len, const void *iv, |
| 297 | unsigned int iv_len, const void *tag, |
| 298 | unsigned int tag_len) |
| 299 | { |
| 300 | mbedtls_gcm_context ctx; |
| 301 | mbedtls_cipher_id_t cipher = MBEDTLS_CIPHER_ID_AES; |
| 302 | unsigned char buf[DEC_OP_BUF_SIZE]; |
| 303 | unsigned char tag_buf[CRYPTO_MAX_TAG_SIZE]; |
| 304 | unsigned char *pt = data_ptr; |
| 305 | size_t dec_len; |
| 306 | int diff, i, rc; |
| 307 | size_t output_length __unused; |
| 308 | |
| 309 | mbedtls_gcm_init(&ctx); |
| 310 | |
| 311 | rc = mbedtls_gcm_setkey(&ctx, cipher, key, key_len * 8); |
| 312 | if (rc != 0) { |
| 313 | rc = CRYPTO_ERR_DECRYPTION; |
| 314 | goto exit_gcm; |
| 315 | } |
| 316 | |
| 317 | #if (MBEDTLS_VERSION_MAJOR < 3) |
| 318 | rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len, NULL, 0); |
| 319 | #else |
| 320 | rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len); |
| 321 | #endif |
| 322 | if (rc != 0) { |
| 323 | rc = CRYPTO_ERR_DECRYPTION; |
| 324 | goto exit_gcm; |
| 325 | } |
| 326 | |
| 327 | while (len > 0) { |
| 328 | dec_len = MIN(sizeof(buf), len); |
| 329 | |
| 330 | #if (MBEDTLS_VERSION_MAJOR < 3) |
| 331 | rc = mbedtls_gcm_update(&ctx, dec_len, pt, buf); |
| 332 | #else |
| 333 | rc = mbedtls_gcm_update(&ctx, pt, dec_len, buf, sizeof(buf), &output_length); |
| 334 | #endif |
| 335 | |
| 336 | if (rc != 0) { |
| 337 | rc = CRYPTO_ERR_DECRYPTION; |
| 338 | goto exit_gcm; |
| 339 | } |
| 340 | |
| 341 | memcpy(pt, buf, dec_len); |
| 342 | pt += dec_len; |
| 343 | len -= dec_len; |
| 344 | } |
| 345 | |
| 346 | #if (MBEDTLS_VERSION_MAJOR < 3) |
| 347 | rc = mbedtls_gcm_finish(&ctx, tag_buf, sizeof(tag_buf)); |
| 348 | #else |
| 349 | rc = mbedtls_gcm_finish(&ctx, NULL, 0, &output_length, tag_buf, sizeof(tag_buf)); |
| 350 | #endif |
| 351 | |
| 352 | if (rc != 0) { |
| 353 | rc = CRYPTO_ERR_DECRYPTION; |
| 354 | goto exit_gcm; |
| 355 | } |
| 356 | |
| 357 | /* Check tag in "constant-time" */ |
| 358 | for (diff = 0, i = 0; i < tag_len; i++) |
| 359 | diff |= ((const unsigned char *)tag)[i] ^ tag_buf[i]; |
| 360 | |
| 361 | if (diff != 0) { |
| 362 | rc = CRYPTO_ERR_DECRYPTION; |
| 363 | goto exit_gcm; |
| 364 | } |
| 365 | |
| 366 | /* GCM decryption success */ |
| 367 | rc = CRYPTO_SUCCESS; |
| 368 | |
| 369 | exit_gcm: |
| 370 | mbedtls_gcm_free(&ctx); |
| 371 | return rc; |
| 372 | } |
| 373 | |
| 374 | /* |
| 375 | * Authenticated decryption of an image |
| 376 | */ |
| 377 | static int auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr, |
| 378 | size_t len, const void *key, unsigned int key_len, |
| 379 | unsigned int key_flags, const void *iv, |
| 380 | unsigned int iv_len, const void *tag, |
| 381 | unsigned int tag_len) |
| 382 | { |
| 383 | int rc; |
| 384 | |
| 385 | assert((key_flags & ENC_KEY_IS_IDENTIFIER) == 0); |
| 386 | |
| 387 | switch (dec_algo) { |
| 388 | case CRYPTO_GCM_DECRYPT: |
| 389 | rc = aes_gcm_decrypt(data_ptr, len, key, key_len, iv, iv_len, |
| 390 | tag, tag_len); |
| 391 | if (rc != 0) |
| 392 | return rc; |
| 393 | break; |
| 394 | default: |
| 395 | return CRYPTO_ERR_DECRYPTION; |
| 396 | } |
| 397 | |
| 398 | return CRYPTO_SUCCESS; |
| 399 | } |
| 400 | #endif /* TF_MBEDTLS_USE_AES_GCM */ |
| 401 | |
| 402 | /* |
| 403 | * Register crypto library descriptor |
| 404 | */ |
| 405 | #if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| 406 | #if TF_MBEDTLS_USE_AES_GCM |
| 407 | REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, |
| 408 | auth_decrypt, NULL); |
| 409 | #else |
| 410 | REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, |
| 411 | NULL, NULL); |
| 412 | #endif |
| 413 | #elif CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY |
| 414 | #if TF_MBEDTLS_USE_AES_GCM |
| 415 | REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL, |
| 416 | auth_decrypt, NULL); |
| 417 | #else |
| 418 | REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL, |
| 419 | NULL, NULL); |
| 420 | #endif |
| 421 | #elif CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY |
| 422 | REGISTER_CRYPTO_LIB(LIB_NAME, init, NULL, NULL, calc_hash, NULL, NULL); |
| 423 | #endif /* CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ |