Yihua Zhang | 04fb58e | 2018-03-08 06:49:24 -0800 | [diff] [blame] | 1 | /* |
| 2 | * |
| 3 | * Copyright 2018 gRPC authors. |
| 4 | * |
| 5 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | * you may not use this file except in compliance with the License. |
| 7 | * You may obtain a copy of the License at |
| 8 | * |
| 9 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | * |
| 11 | * Unless required by applicable law or agreed to in writing, software |
| 12 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | * See the License for the specific language governing permissions and |
| 15 | * limitations under the License. |
| 16 | * |
| 17 | */ |
| 18 | |
| 19 | #include <grpc/support/port_platform.h> |
| 20 | |
Muxi Yan | b24b212 | 2018-08-14 10:21:27 -0700 | [diff] [blame] | 21 | #include "src/core/tsi/grpc_shadow_boringssl.h" |
| 22 | |
Yihua Zhang | 04fb58e | 2018-03-08 06:49:24 -0800 | [diff] [blame] | 23 | #include "src/core/tsi/alts/crypt/gsec.h" |
| 24 | |
| 25 | #include <openssl/bio.h> |
| 26 | #include <openssl/buffer.h> |
| 27 | #include <openssl/err.h> |
| 28 | #include <openssl/evp.h> |
| 29 | #include <openssl/hmac.h> |
| 30 | #include <string.h> |
| 31 | |
| 32 | #include <grpc/support/alloc.h> |
| 33 | |
| 34 | constexpr size_t kKdfKeyLen = 32; |
| 35 | constexpr size_t kKdfCounterLen = 6; |
| 36 | constexpr size_t kKdfCounterOffset = 2; |
| 37 | constexpr size_t kRekeyAeadKeyLen = kAes128GcmKeyLength; |
| 38 | |
| 39 | /* Struct for additional data required if rekeying is enabled. */ |
| 40 | struct gsec_aes_gcm_aead_rekey_data { |
| 41 | uint8_t kdf_counter[kKdfCounterLen]; |
| 42 | uint8_t nonce_mask[kAesGcmNonceLength]; |
| 43 | }; |
| 44 | |
| 45 | /* Main struct for AES_GCM crypter interface. */ |
| 46 | struct gsec_aes_gcm_aead_crypter { |
| 47 | gsec_aead_crypter crypter; |
| 48 | size_t key_length; |
| 49 | size_t nonce_length; |
| 50 | size_t tag_length; |
| 51 | uint8_t* key; |
| 52 | gsec_aes_gcm_aead_rekey_data* rekey_data; |
| 53 | EVP_CIPHER_CTX* ctx; |
| 54 | }; |
| 55 | |
| 56 | static char* aes_gcm_get_openssl_errors() { |
| 57 | BIO* bio = BIO_new(BIO_s_mem()); |
| 58 | ERR_print_errors(bio); |
| 59 | BUF_MEM* mem = nullptr; |
| 60 | char* error_msg = nullptr; |
| 61 | BIO_get_mem_ptr(bio, &mem); |
| 62 | if (mem != nullptr) { |
| 63 | error_msg = static_cast<char*>(gpr_malloc(mem->length + 1)); |
| 64 | memcpy(error_msg, mem->data, mem->length); |
| 65 | error_msg[mem->length] = '\0'; |
| 66 | } |
| 67 | BIO_free_all(bio); |
| 68 | return error_msg; |
| 69 | } |
| 70 | |
| 71 | static void aes_gcm_format_errors(const char* error_msg, char** error_details) { |
| 72 | if (error_details == nullptr) { |
| 73 | return; |
| 74 | } |
| 75 | unsigned long error = ERR_get_error(); |
| 76 | if (error == 0 && error_msg != nullptr) { |
| 77 | *error_details = static_cast<char*>(gpr_malloc(strlen(error_msg) + 1)); |
| 78 | memcpy(*error_details, error_msg, strlen(error_msg) + 1); |
| 79 | return; |
| 80 | } |
| 81 | char* openssl_errors = aes_gcm_get_openssl_errors(); |
| 82 | if (openssl_errors != nullptr && error_msg != nullptr) { |
| 83 | size_t len = strlen(error_msg) + strlen(openssl_errors) + 2; /* ", " */ |
| 84 | *error_details = static_cast<char*>(gpr_malloc(len + 1)); |
| 85 | snprintf(*error_details, len + 1, "%s, %s", error_msg, openssl_errors); |
| 86 | gpr_free(openssl_errors); |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | static grpc_status_code gsec_aes_gcm_aead_crypter_max_ciphertext_and_tag_length( |
| 91 | const gsec_aead_crypter* crypter, size_t plaintext_length, |
| 92 | size_t* max_ciphertext_and_tag_length, char** error_details) { |
| 93 | if (max_ciphertext_and_tag_length == nullptr) { |
| 94 | aes_gcm_format_errors("max_ciphertext_and_tag_length is nullptr.", |
| 95 | error_details); |
| 96 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 97 | } |
| 98 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 99 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 100 | const_cast<gsec_aead_crypter*>(crypter)); |
| 101 | *max_ciphertext_and_tag_length = |
| 102 | plaintext_length + aes_gcm_crypter->tag_length; |
| 103 | return GRPC_STATUS_OK; |
| 104 | } |
| 105 | |
| 106 | static grpc_status_code gsec_aes_gcm_aead_crypter_max_plaintext_length( |
| 107 | const gsec_aead_crypter* crypter, size_t ciphertext_and_tag_length, |
| 108 | size_t* max_plaintext_length, char** error_details) { |
| 109 | if (max_plaintext_length == nullptr) { |
| 110 | aes_gcm_format_errors("max_plaintext_length is nullptr.", error_details); |
| 111 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 112 | } |
| 113 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 114 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 115 | const_cast<gsec_aead_crypter*>(crypter)); |
| 116 | if (ciphertext_and_tag_length < aes_gcm_crypter->tag_length) { |
| 117 | *max_plaintext_length = 0; |
| 118 | aes_gcm_format_errors( |
| 119 | "ciphertext_and_tag_length is smaller than tag_length.", error_details); |
| 120 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 121 | } |
| 122 | *max_plaintext_length = |
| 123 | ciphertext_and_tag_length - aes_gcm_crypter->tag_length; |
| 124 | return GRPC_STATUS_OK; |
| 125 | } |
| 126 | |
| 127 | static grpc_status_code gsec_aes_gcm_aead_crypter_nonce_length( |
| 128 | const gsec_aead_crypter* crypter, size_t* nonce_length, |
| 129 | char** error_details) { |
| 130 | if (nonce_length == nullptr) { |
| 131 | aes_gcm_format_errors("nonce_length is nullptr.", error_details); |
| 132 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 133 | } |
| 134 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 135 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 136 | const_cast<gsec_aead_crypter*>(crypter)); |
| 137 | *nonce_length = aes_gcm_crypter->nonce_length; |
| 138 | return GRPC_STATUS_OK; |
| 139 | } |
| 140 | |
| 141 | static grpc_status_code gsec_aes_gcm_aead_crypter_key_length( |
| 142 | const gsec_aead_crypter* crypter, size_t* key_length, |
| 143 | char** error_details) { |
| 144 | if (key_length == nullptr) { |
| 145 | aes_gcm_format_errors("key_length is nullptr.", error_details); |
| 146 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 147 | } |
| 148 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 149 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 150 | const_cast<gsec_aead_crypter*>(crypter)); |
| 151 | *key_length = aes_gcm_crypter->key_length; |
| 152 | return GRPC_STATUS_OK; |
| 153 | } |
| 154 | |
| 155 | static grpc_status_code gsec_aes_gcm_aead_crypter_tag_length( |
| 156 | const gsec_aead_crypter* crypter, size_t* tag_length, |
| 157 | char** error_details) { |
| 158 | if (tag_length == nullptr) { |
| 159 | aes_gcm_format_errors("tag_length is nullptr.", error_details); |
| 160 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 161 | } |
| 162 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 163 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 164 | const_cast<gsec_aead_crypter*>(crypter)); |
| 165 | *tag_length = aes_gcm_crypter->tag_length; |
| 166 | return GRPC_STATUS_OK; |
| 167 | } |
| 168 | |
| 169 | static void aes_gcm_mask_nonce(uint8_t* dst, const uint8_t* nonce, |
| 170 | const uint8_t* mask) { |
| 171 | uint64_t mask1; |
| 172 | uint32_t mask2; |
| 173 | memcpy(&mask1, mask, sizeof(mask1)); |
| 174 | memcpy(&mask2, mask + sizeof(mask1), sizeof(mask2)); |
| 175 | uint64_t nonce1; |
| 176 | uint32_t nonce2; |
| 177 | memcpy(&nonce1, nonce, sizeof(nonce1)); |
| 178 | memcpy(&nonce2, nonce + sizeof(nonce1), sizeof(nonce2)); |
| 179 | nonce1 ^= mask1; |
| 180 | nonce2 ^= mask2; |
| 181 | memcpy(dst, &nonce1, sizeof(nonce1)); |
| 182 | memcpy(dst + sizeof(nonce1), &nonce2, sizeof(nonce2)); |
| 183 | } |
| 184 | |
| 185 | static grpc_status_code aes_gcm_derive_aead_key(uint8_t* dst, |
| 186 | const uint8_t* kdf_key, |
| 187 | const uint8_t* kdf_counter) { |
| 188 | unsigned char buf[EVP_MAX_MD_SIZE]; |
| 189 | unsigned char ctr = 1; |
| 190 | #if OPENSSL_VERSION_NUMBER < 0x10100000L |
| 191 | HMAC_CTX hmac; |
| 192 | HMAC_CTX_init(&hmac); |
| 193 | if (!HMAC_Init_ex(&hmac, kdf_key, kKdfKeyLen, EVP_sha256(), nullptr) || |
| 194 | !HMAC_Update(&hmac, kdf_counter, kKdfCounterLen) || |
| 195 | !HMAC_Update(&hmac, &ctr, 1) || !HMAC_Final(&hmac, buf, nullptr)) { |
| 196 | HMAC_CTX_cleanup(&hmac); |
| 197 | return GRPC_STATUS_INTERNAL; |
| 198 | } |
| 199 | HMAC_CTX_cleanup(&hmac); |
| 200 | #else |
| 201 | HMAC_CTX* hmac = HMAC_CTX_new(); |
| 202 | if (hmac == nullptr) { |
| 203 | return GRPC_STATUS_INTERNAL; |
| 204 | } |
| 205 | if (!HMAC_Init_ex(hmac, kdf_key, kKdfKeyLen, EVP_sha256(), nullptr) || |
| 206 | !HMAC_Update(hmac, kdf_counter, kKdfCounterLen) || |
| 207 | !HMAC_Update(hmac, &ctr, 1) || !HMAC_Final(hmac, buf, nullptr)) { |
| 208 | HMAC_CTX_free(hmac); |
| 209 | return GRPC_STATUS_INTERNAL; |
| 210 | } |
| 211 | HMAC_CTX_free(hmac); |
| 212 | #endif |
| 213 | memcpy(dst, buf, kRekeyAeadKeyLen); |
| 214 | return GRPC_STATUS_OK; |
| 215 | } |
| 216 | |
| 217 | static grpc_status_code aes_gcm_rekey_if_required( |
| 218 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter, const uint8_t* nonce, |
| 219 | char** error_details) { |
| 220 | // If rekey_data is nullptr, then rekeying is not supported and not required. |
| 221 | // If bytes 2-7 of kdf_counter differ from the (per message) nonce, then the |
| 222 | // encryption key is recomputed from a new kdf_counter to ensure that we don't |
| 223 | // encrypt more than 2^16 messages per encryption key (in each direction). |
| 224 | if (aes_gcm_crypter->rekey_data == nullptr || |
| 225 | memcmp(aes_gcm_crypter->rekey_data->kdf_counter, |
| 226 | nonce + kKdfCounterOffset, kKdfCounterLen) == 0) { |
| 227 | return GRPC_STATUS_OK; |
| 228 | } |
| 229 | memcpy(aes_gcm_crypter->rekey_data->kdf_counter, nonce + kKdfCounterOffset, |
| 230 | kKdfCounterLen); |
| 231 | uint8_t aead_key[kRekeyAeadKeyLen]; |
| 232 | if (aes_gcm_derive_aead_key(aead_key, aes_gcm_crypter->key, |
| 233 | aes_gcm_crypter->rekey_data->kdf_counter) != |
| 234 | GRPC_STATUS_OK) { |
| 235 | aes_gcm_format_errors("Rekeying failed in key derivation.", error_details); |
| 236 | return GRPC_STATUS_INTERNAL; |
| 237 | } |
| 238 | if (!EVP_DecryptInit_ex(aes_gcm_crypter->ctx, nullptr, nullptr, aead_key, |
| 239 | nullptr)) { |
| 240 | aes_gcm_format_errors("Rekeying failed in context update.", error_details); |
| 241 | return GRPC_STATUS_INTERNAL; |
| 242 | } |
| 243 | return GRPC_STATUS_OK; |
| 244 | } |
| 245 | |
| 246 | static grpc_status_code gsec_aes_gcm_aead_crypter_encrypt_iovec( |
| 247 | gsec_aead_crypter* crypter, const uint8_t* nonce, size_t nonce_length, |
| 248 | const struct iovec* aad_vec, size_t aad_vec_length, |
| 249 | const struct iovec* plaintext_vec, size_t plaintext_vec_length, |
| 250 | struct iovec ciphertext_vec, size_t* ciphertext_bytes_written, |
| 251 | char** error_details) { |
| 252 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 253 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>(crypter); |
| 254 | // Input checks |
| 255 | if (nonce == nullptr) { |
| 256 | aes_gcm_format_errors("Nonce buffer is nullptr.", error_details); |
| 257 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 258 | } |
| 259 | if (kAesGcmNonceLength != nonce_length) { |
| 260 | aes_gcm_format_errors("Nonce buffer has the wrong length.", error_details); |
| 261 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 262 | } |
| 263 | if (aad_vec_length > 0 && aad_vec == nullptr) { |
| 264 | aes_gcm_format_errors("Non-zero aad_vec_length but aad_vec is nullptr.", |
| 265 | error_details); |
| 266 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 267 | } |
| 268 | if (plaintext_vec_length > 0 && plaintext_vec == nullptr) { |
| 269 | aes_gcm_format_errors( |
| 270 | "Non-zero plaintext_vec_length but plaintext_vec is nullptr.", |
| 271 | error_details); |
| 272 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 273 | } |
| 274 | if (ciphertext_bytes_written == nullptr) { |
| 275 | aes_gcm_format_errors("bytes_written is nullptr.", error_details); |
| 276 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 277 | } |
| 278 | *ciphertext_bytes_written = 0; |
| 279 | // rekey if required |
| 280 | if (aes_gcm_rekey_if_required(aes_gcm_crypter, nonce, error_details) != |
| 281 | GRPC_STATUS_OK) { |
| 282 | return GRPC_STATUS_INTERNAL; |
| 283 | } |
| 284 | // mask nonce if required |
| 285 | const uint8_t* nonce_aead = nonce; |
| 286 | uint8_t nonce_masked[kAesGcmNonceLength]; |
| 287 | if (aes_gcm_crypter->rekey_data != nullptr) { |
| 288 | aes_gcm_mask_nonce(nonce_masked, aes_gcm_crypter->rekey_data->nonce_mask, |
| 289 | nonce); |
| 290 | nonce_aead = nonce_masked; |
| 291 | } |
| 292 | // init openssl context |
| 293 | if (!EVP_EncryptInit_ex(aes_gcm_crypter->ctx, nullptr, nullptr, nullptr, |
| 294 | nonce_aead)) { |
| 295 | aes_gcm_format_errors("Initializing nonce failed", error_details); |
| 296 | return GRPC_STATUS_INTERNAL; |
| 297 | } |
| 298 | // process aad |
| 299 | size_t i; |
| 300 | for (i = 0; i < aad_vec_length; i++) { |
| 301 | const uint8_t* aad = static_cast<uint8_t*>(aad_vec[i].iov_base); |
| 302 | size_t aad_length = aad_vec[i].iov_len; |
| 303 | if (aad_length == 0) { |
| 304 | continue; |
| 305 | } |
| 306 | size_t aad_bytes_read = 0; |
| 307 | if (aad == nullptr) { |
| 308 | aes_gcm_format_errors("aad is nullptr.", error_details); |
| 309 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 310 | } |
| 311 | if (!EVP_EncryptUpdate(aes_gcm_crypter->ctx, nullptr, |
| 312 | reinterpret_cast<int*>(&aad_bytes_read), aad, |
| 313 | static_cast<int>(aad_length)) || |
| 314 | aad_bytes_read != aad_length) { |
| 315 | aes_gcm_format_errors("Setting authenticated associated data failed", |
| 316 | error_details); |
| 317 | return GRPC_STATUS_INTERNAL; |
| 318 | } |
| 319 | } |
| 320 | uint8_t* ciphertext = static_cast<uint8_t*>(ciphertext_vec.iov_base); |
| 321 | size_t ciphertext_length = ciphertext_vec.iov_len; |
| 322 | if (ciphertext == nullptr) { |
| 323 | aes_gcm_format_errors("ciphertext is nullptr.", error_details); |
| 324 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 325 | } |
| 326 | // process plaintext |
| 327 | for (i = 0; i < plaintext_vec_length; i++) { |
| 328 | const uint8_t* plaintext = static_cast<uint8_t*>(plaintext_vec[i].iov_base); |
| 329 | size_t plaintext_length = plaintext_vec[i].iov_len; |
| 330 | if (plaintext == nullptr) { |
| 331 | if (plaintext_length == 0) { |
| 332 | continue; |
| 333 | } |
| 334 | aes_gcm_format_errors("plaintext is nullptr.", error_details); |
| 335 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 336 | } |
| 337 | if (ciphertext_length < plaintext_length) { |
| 338 | aes_gcm_format_errors( |
| 339 | "ciphertext is not large enough to hold the result.", error_details); |
| 340 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 341 | } |
| 342 | int bytes_written = 0; |
| 343 | int bytes_to_write = static_cast<int>(plaintext_length); |
| 344 | if (!EVP_EncryptUpdate(aes_gcm_crypter->ctx, ciphertext, &bytes_written, |
| 345 | plaintext, bytes_to_write)) { |
| 346 | aes_gcm_format_errors("Encrypting plaintext failed.", error_details); |
| 347 | return GRPC_STATUS_INTERNAL; |
| 348 | } |
| 349 | if (bytes_written > bytes_to_write) { |
| 350 | aes_gcm_format_errors("More bytes written than expected.", error_details); |
| 351 | return GRPC_STATUS_INTERNAL; |
| 352 | } |
| 353 | ciphertext += bytes_written; |
| 354 | ciphertext_length -= bytes_written; |
| 355 | } |
| 356 | int bytes_written_temp = 0; |
| 357 | if (!EVP_EncryptFinal_ex(aes_gcm_crypter->ctx, nullptr, |
| 358 | &bytes_written_temp)) { |
| 359 | aes_gcm_format_errors("Finalizing encryption failed.", error_details); |
| 360 | return GRPC_STATUS_INTERNAL; |
| 361 | } |
| 362 | if (bytes_written_temp != 0) { |
| 363 | aes_gcm_format_errors("Openssl wrote some unexpected bytes.", |
| 364 | error_details); |
| 365 | return GRPC_STATUS_INTERNAL; |
| 366 | } |
| 367 | if (ciphertext_length < kAesGcmTagLength) { |
| 368 | aes_gcm_format_errors("ciphertext is too small to hold a tag.", |
| 369 | error_details); |
| 370 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 371 | } |
| 372 | |
| 373 | if (!EVP_CIPHER_CTX_ctrl(aes_gcm_crypter->ctx, EVP_CTRL_GCM_GET_TAG, |
| 374 | kAesGcmTagLength, ciphertext)) { |
| 375 | aes_gcm_format_errors("Writing tag failed.", error_details); |
| 376 | return GRPC_STATUS_INTERNAL; |
| 377 | } |
| 378 | ciphertext += kAesGcmTagLength; |
| 379 | ciphertext_length -= kAesGcmTagLength; |
| 380 | *ciphertext_bytes_written = ciphertext_vec.iov_len - ciphertext_length; |
| 381 | return GRPC_STATUS_OK; |
| 382 | } |
| 383 | |
| 384 | static grpc_status_code gsec_aes_gcm_aead_crypter_decrypt_iovec( |
| 385 | gsec_aead_crypter* crypter, const uint8_t* nonce, size_t nonce_length, |
| 386 | const struct iovec* aad_vec, size_t aad_vec_length, |
| 387 | const struct iovec* ciphertext_vec, size_t ciphertext_vec_length, |
| 388 | struct iovec plaintext_vec, size_t* plaintext_bytes_written, |
| 389 | char** error_details) { |
| 390 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 391 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 392 | const_cast<gsec_aead_crypter*>(crypter)); |
| 393 | if (nonce == nullptr) { |
| 394 | aes_gcm_format_errors("Nonce buffer is nullptr.", error_details); |
| 395 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 396 | } |
| 397 | if (kAesGcmNonceLength != nonce_length) { |
| 398 | aes_gcm_format_errors("Nonce buffer has the wrong length.", error_details); |
| 399 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 400 | } |
| 401 | if (aad_vec_length > 0 && aad_vec == nullptr) { |
| 402 | aes_gcm_format_errors("Non-zero aad_vec_length but aad_vec is nullptr.", |
| 403 | error_details); |
| 404 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 405 | } |
| 406 | if (ciphertext_vec_length > 0 && ciphertext_vec == nullptr) { |
| 407 | aes_gcm_format_errors( |
| 408 | "Non-zero plaintext_vec_length but plaintext_vec is nullptr.", |
| 409 | error_details); |
| 410 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 411 | } |
| 412 | // Compute the total length so we can ensure we don't pass the tag into |
| 413 | // EVP_decrypt. |
| 414 | size_t total_ciphertext_length = 0; |
| 415 | size_t i; |
| 416 | for (i = 0; i < ciphertext_vec_length; i++) { |
| 417 | total_ciphertext_length += ciphertext_vec[i].iov_len; |
| 418 | } |
| 419 | if (total_ciphertext_length < kAesGcmTagLength) { |
| 420 | aes_gcm_format_errors("ciphertext is too small to hold a tag.", |
| 421 | error_details); |
| 422 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 423 | } |
| 424 | if (plaintext_bytes_written == nullptr) { |
| 425 | aes_gcm_format_errors("bytes_written is nullptr.", error_details); |
| 426 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 427 | } |
| 428 | *plaintext_bytes_written = 0; |
| 429 | // rekey if required |
| 430 | if (aes_gcm_rekey_if_required(aes_gcm_crypter, nonce, error_details) != |
| 431 | GRPC_STATUS_OK) { |
| 432 | aes_gcm_format_errors("Rekeying failed.", error_details); |
| 433 | return GRPC_STATUS_INTERNAL; |
| 434 | } |
| 435 | // mask nonce if required |
| 436 | const uint8_t* nonce_aead = nonce; |
| 437 | uint8_t nonce_masked[kAesGcmNonceLength]; |
| 438 | if (aes_gcm_crypter->rekey_data != nullptr) { |
| 439 | aes_gcm_mask_nonce(nonce_masked, aes_gcm_crypter->rekey_data->nonce_mask, |
| 440 | nonce); |
| 441 | nonce_aead = nonce_masked; |
| 442 | } |
| 443 | // init openssl context |
| 444 | if (!EVP_DecryptInit_ex(aes_gcm_crypter->ctx, nullptr, nullptr, nullptr, |
| 445 | nonce_aead)) { |
| 446 | aes_gcm_format_errors("Initializing nonce failed.", error_details); |
| 447 | return GRPC_STATUS_INTERNAL; |
| 448 | } |
| 449 | // process aad |
| 450 | for (i = 0; i < aad_vec_length; i++) { |
| 451 | const uint8_t* aad = static_cast<uint8_t*>(aad_vec[i].iov_base); |
| 452 | size_t aad_length = aad_vec[i].iov_len; |
| 453 | if (aad_length == 0) { |
| 454 | continue; |
| 455 | } |
| 456 | size_t aad_bytes_read = 0; |
| 457 | if (aad == nullptr) { |
| 458 | aes_gcm_format_errors("aad is nullptr.", error_details); |
| 459 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 460 | } |
| 461 | if (!EVP_DecryptUpdate(aes_gcm_crypter->ctx, nullptr, |
| 462 | reinterpret_cast<int*>(&aad_bytes_read), aad, |
| 463 | static_cast<int>(aad_length)) || |
| 464 | aad_bytes_read != aad_length) { |
| 465 | aes_gcm_format_errors("Setting authenticated associated data failed.", |
| 466 | error_details); |
| 467 | return GRPC_STATUS_INTERNAL; |
| 468 | } |
| 469 | } |
| 470 | // process ciphertext |
| 471 | uint8_t* plaintext = static_cast<uint8_t*>(plaintext_vec.iov_base); |
| 472 | size_t plaintext_length = plaintext_vec.iov_len; |
| 473 | if (plaintext_length > 0 && plaintext == nullptr) { |
| 474 | aes_gcm_format_errors( |
| 475 | "plaintext is nullptr, but plaintext_length is positive.", |
| 476 | error_details); |
| 477 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 478 | } |
| 479 | const uint8_t* ciphertext = nullptr; |
| 480 | size_t ciphertext_length = 0; |
| 481 | for (i = 0; |
| 482 | i < ciphertext_vec_length && total_ciphertext_length > kAesGcmTagLength; |
| 483 | i++) { |
| 484 | ciphertext = static_cast<uint8_t*>(ciphertext_vec[i].iov_base); |
| 485 | ciphertext_length = ciphertext_vec[i].iov_len; |
| 486 | if (ciphertext == nullptr) { |
| 487 | if (ciphertext_length == 0) { |
| 488 | continue; |
| 489 | } |
| 490 | aes_gcm_format_errors("ciphertext is nullptr.", error_details); |
| 491 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 492 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 493 | } |
| 494 | size_t bytes_written = 0; |
| 495 | size_t bytes_to_write = ciphertext_length; |
| 496 | // Don't include the tag |
| 497 | if (bytes_to_write > total_ciphertext_length - kAesGcmTagLength) { |
| 498 | bytes_to_write = total_ciphertext_length - kAesGcmTagLength; |
| 499 | } |
| 500 | if (plaintext_length < bytes_to_write) { |
| 501 | aes_gcm_format_errors( |
| 502 | "Not enough plaintext buffer to hold encrypted ciphertext.", |
| 503 | error_details); |
| 504 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 505 | } |
| 506 | if (!EVP_DecryptUpdate(aes_gcm_crypter->ctx, plaintext, |
| 507 | reinterpret_cast<int*>(&bytes_written), ciphertext, |
| 508 | static_cast<int>(bytes_to_write))) { |
| 509 | aes_gcm_format_errors("Decrypting ciphertext failed.", error_details); |
| 510 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 511 | return GRPC_STATUS_INTERNAL; |
| 512 | } |
| 513 | if (bytes_written > ciphertext_length) { |
| 514 | aes_gcm_format_errors("More bytes written than expected.", error_details); |
| 515 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 516 | return GRPC_STATUS_INTERNAL; |
| 517 | } |
| 518 | ciphertext += bytes_written; |
| 519 | ciphertext_length -= bytes_written; |
| 520 | total_ciphertext_length -= bytes_written; |
| 521 | plaintext += bytes_written; |
| 522 | plaintext_length -= bytes_written; |
| 523 | } |
| 524 | if (total_ciphertext_length > kAesGcmTagLength) { |
| 525 | aes_gcm_format_errors( |
| 526 | "Not enough plaintext buffer to hold encrypted ciphertext.", |
| 527 | error_details); |
| 528 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 529 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 530 | } |
| 531 | uint8_t tag[kAesGcmTagLength]; |
| 532 | uint8_t* tag_tmp = tag; |
| 533 | if (ciphertext_length > 0) { |
| 534 | memcpy(tag_tmp, ciphertext, ciphertext_length); |
| 535 | tag_tmp += ciphertext_length; |
| 536 | total_ciphertext_length -= ciphertext_length; |
| 537 | } |
| 538 | for (; i < ciphertext_vec_length; i++) { |
| 539 | ciphertext = static_cast<uint8_t*>(ciphertext_vec[i].iov_base); |
| 540 | ciphertext_length = ciphertext_vec[i].iov_len; |
| 541 | if (ciphertext == nullptr) { |
| 542 | if (ciphertext_length == 0) { |
| 543 | continue; |
| 544 | } |
| 545 | aes_gcm_format_errors("ciphertext is nullptr.", error_details); |
| 546 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 547 | return GRPC_STATUS_INVALID_ARGUMENT; |
| 548 | } |
| 549 | memcpy(tag_tmp, ciphertext, ciphertext_length); |
| 550 | tag_tmp += ciphertext_length; |
| 551 | total_ciphertext_length -= ciphertext_length; |
| 552 | } |
| 553 | if (!EVP_CIPHER_CTX_ctrl(aes_gcm_crypter->ctx, EVP_CTRL_GCM_SET_TAG, |
| 554 | kAesGcmTagLength, reinterpret_cast<void*>(tag))) { |
| 555 | aes_gcm_format_errors("Setting tag failed.", error_details); |
| 556 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 557 | return GRPC_STATUS_INTERNAL; |
| 558 | } |
| 559 | int bytes_written_temp = 0; |
| 560 | if (!EVP_DecryptFinal_ex(aes_gcm_crypter->ctx, nullptr, |
| 561 | &bytes_written_temp)) { |
| 562 | aes_gcm_format_errors("Checking tag failed.", error_details); |
| 563 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 564 | return GRPC_STATUS_FAILED_PRECONDITION; |
| 565 | } |
| 566 | if (bytes_written_temp != 0) { |
| 567 | aes_gcm_format_errors("Openssl wrote some unexpected bytes.", |
| 568 | error_details); |
| 569 | memset(plaintext_vec.iov_base, 0x00, plaintext_vec.iov_len); |
| 570 | return GRPC_STATUS_INTERNAL; |
| 571 | } |
| 572 | *plaintext_bytes_written = plaintext_vec.iov_len - plaintext_length; |
| 573 | return GRPC_STATUS_OK; |
| 574 | } |
| 575 | |
| 576 | static void gsec_aes_gcm_aead_crypter_destroy(gsec_aead_crypter* crypter) { |
| 577 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 578 | reinterpret_cast<gsec_aes_gcm_aead_crypter*>( |
| 579 | const_cast<gsec_aead_crypter*>(crypter)); |
| 580 | gpr_free(aes_gcm_crypter->key); |
| 581 | gpr_free(aes_gcm_crypter->rekey_data); |
| 582 | EVP_CIPHER_CTX_free(aes_gcm_crypter->ctx); |
| 583 | } |
| 584 | |
| 585 | static const gsec_aead_crypter_vtable vtable = { |
| 586 | gsec_aes_gcm_aead_crypter_encrypt_iovec, |
| 587 | gsec_aes_gcm_aead_crypter_decrypt_iovec, |
| 588 | gsec_aes_gcm_aead_crypter_max_ciphertext_and_tag_length, |
| 589 | gsec_aes_gcm_aead_crypter_max_plaintext_length, |
| 590 | gsec_aes_gcm_aead_crypter_nonce_length, |
| 591 | gsec_aes_gcm_aead_crypter_key_length, |
| 592 | gsec_aes_gcm_aead_crypter_tag_length, |
| 593 | gsec_aes_gcm_aead_crypter_destroy}; |
| 594 | |
| 595 | static grpc_status_code aes_gcm_new_evp_cipher_ctx( |
| 596 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter, char** error_details) { |
| 597 | const EVP_CIPHER* cipher = nullptr; |
| 598 | bool is_rekey = aes_gcm_crypter->rekey_data != nullptr; |
| 599 | switch (is_rekey ? kRekeyAeadKeyLen : aes_gcm_crypter->key_length) { |
| 600 | case kAes128GcmKeyLength: |
| 601 | cipher = EVP_aes_128_gcm(); |
| 602 | break; |
| 603 | case kAes256GcmKeyLength: |
| 604 | cipher = EVP_aes_256_gcm(); |
| 605 | break; |
| 606 | } |
| 607 | const uint8_t* aead_key = aes_gcm_crypter->key; |
| 608 | uint8_t aead_key_rekey[kRekeyAeadKeyLen]; |
| 609 | if (is_rekey) { |
| 610 | if (aes_gcm_derive_aead_key(aead_key_rekey, aes_gcm_crypter->key, |
| 611 | aes_gcm_crypter->rekey_data->kdf_counter) != |
| 612 | GRPC_STATUS_OK) { |
| 613 | aes_gcm_format_errors("Deriving key failed.", error_details); |
| 614 | return GRPC_STATUS_INTERNAL; |
| 615 | } |
| 616 | aead_key = aead_key_rekey; |
| 617 | } |
| 618 | if (!EVP_DecryptInit_ex(aes_gcm_crypter->ctx, cipher, nullptr, aead_key, |
| 619 | nullptr)) { |
| 620 | aes_gcm_format_errors("Setting key failed.", error_details); |
| 621 | return GRPC_STATUS_INTERNAL; |
| 622 | } |
| 623 | if (!EVP_CIPHER_CTX_ctrl(aes_gcm_crypter->ctx, EVP_CTRL_GCM_SET_IVLEN, |
| 624 | static_cast<int>(aes_gcm_crypter->nonce_length), |
| 625 | nullptr)) { |
| 626 | aes_gcm_format_errors("Setting nonce length failed.", error_details); |
| 627 | return GRPC_STATUS_INTERNAL; |
| 628 | } |
| 629 | return GRPC_STATUS_OK; |
| 630 | } |
| 631 | |
| 632 | grpc_status_code gsec_aes_gcm_aead_crypter_create(const uint8_t* key, |
| 633 | size_t key_length, |
| 634 | size_t nonce_length, |
| 635 | size_t tag_length, bool rekey, |
| 636 | gsec_aead_crypter** crypter, |
| 637 | char** error_details) { |
| 638 | if (key == nullptr) { |
| 639 | aes_gcm_format_errors("key is nullptr.", error_details); |
| 640 | return GRPC_STATUS_FAILED_PRECONDITION; |
| 641 | } |
| 642 | if (crypter == nullptr) { |
| 643 | aes_gcm_format_errors("crypter is nullptr.", error_details); |
| 644 | return GRPC_STATUS_FAILED_PRECONDITION; |
| 645 | } |
| 646 | *crypter = nullptr; |
| 647 | if ((rekey && key_length != kAes128GcmRekeyKeyLength) || |
| 648 | (!rekey && key_length != kAes128GcmKeyLength && |
| 649 | key_length != kAes256GcmKeyLength) || |
| 650 | (tag_length != kAesGcmTagLength) || |
| 651 | (nonce_length != kAesGcmNonceLength)) { |
| 652 | aes_gcm_format_errors( |
| 653 | "Invalid key and/or nonce and/or tag length are provided at AEAD " |
| 654 | "crypter instance construction time.", |
| 655 | error_details); |
| 656 | return GRPC_STATUS_FAILED_PRECONDITION; |
| 657 | } |
| 658 | gsec_aes_gcm_aead_crypter* aes_gcm_crypter = |
| 659 | static_cast<gsec_aes_gcm_aead_crypter*>( |
| 660 | gpr_malloc(sizeof(gsec_aes_gcm_aead_crypter))); |
| 661 | aes_gcm_crypter->crypter.vtable = &vtable; |
| 662 | aes_gcm_crypter->nonce_length = nonce_length; |
| 663 | aes_gcm_crypter->tag_length = tag_length; |
| 664 | if (rekey) { |
| 665 | aes_gcm_crypter->key_length = kKdfKeyLen; |
| 666 | aes_gcm_crypter->rekey_data = static_cast<gsec_aes_gcm_aead_rekey_data*>( |
| 667 | gpr_malloc(sizeof(gsec_aes_gcm_aead_rekey_data))); |
| 668 | memcpy(aes_gcm_crypter->rekey_data->nonce_mask, key + kKdfKeyLen, |
| 669 | kAesGcmNonceLength); |
| 670 | // Set kdf_counter to all-zero for initial key derivation. |
| 671 | memset(aes_gcm_crypter->rekey_data->kdf_counter, 0, kKdfCounterLen); |
| 672 | } else { |
| 673 | aes_gcm_crypter->key_length = key_length; |
| 674 | aes_gcm_crypter->rekey_data = nullptr; |
| 675 | } |
| 676 | aes_gcm_crypter->key = |
| 677 | static_cast<uint8_t*>(gpr_malloc(aes_gcm_crypter->key_length)); |
| 678 | memcpy(aes_gcm_crypter->key, key, aes_gcm_crypter->key_length); |
| 679 | aes_gcm_crypter->ctx = EVP_CIPHER_CTX_new(); |
| 680 | grpc_status_code status = |
| 681 | aes_gcm_new_evp_cipher_ctx(aes_gcm_crypter, error_details); |
| 682 | if (status != GRPC_STATUS_OK) { |
| 683 | gsec_aes_gcm_aead_crypter_destroy(&aes_gcm_crypter->crypter); |
| 684 | gpr_free(aes_gcm_crypter); |
| 685 | return status; |
| 686 | } |
| 687 | *crypter = &aes_gcm_crypter->crypter; |
| 688 | return GRPC_STATUS_OK; |
| 689 | } |