| /* Copyright (c) 2021, Google Inc. |
| * |
| * Permission to use, copy, modify, and/or distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |
| * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
| * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ |
| |
| #include <openssl/bytestring.h> |
| #include <openssl/curve25519.h> |
| #include <openssl/err.h> |
| #include <openssl/hkdf.h> |
| #include <openssl/ssl.h> |
| |
| #include "internal.h" |
| |
| |
| #if defined(OPENSSL_MSAN) |
| #define NO_SANITIZE_MEMORY __attribute__((no_sanitize("memory"))) |
| #else |
| #define NO_SANITIZE_MEMORY |
| #endif |
| |
| BSSL_NAMESPACE_BEGIN |
| |
| // ssl_client_hello_write_without_extensions serializes |client_hello| into |
| // |out|, omitting the length-prefixed extensions. It serializes individual |
| // fields, starting with |client_hello->version|, and ignores the |
| // |client_hello->client_hello| field. It returns true on success and false on |
| // failure. |
| static bool ssl_client_hello_write_without_extensions( |
| const SSL_CLIENT_HELLO *client_hello, CBB *out) { |
| CBB cbb; |
| if (!CBB_add_u16(out, client_hello->version) || |
| !CBB_add_bytes(out, client_hello->random, client_hello->random_len) || |
| !CBB_add_u8_length_prefixed(out, &cbb) || |
| !CBB_add_bytes(&cbb, client_hello->session_id, |
| client_hello->session_id_len) || |
| !CBB_add_u16_length_prefixed(out, &cbb) || |
| !CBB_add_bytes(&cbb, client_hello->cipher_suites, |
| client_hello->cipher_suites_len) || |
| !CBB_add_u8_length_prefixed(out, &cbb) || |
| !CBB_add_bytes(&cbb, client_hello->compression_methods, |
| client_hello->compression_methods_len) || |
| !CBB_flush(out)) { |
| return false; |
| } |
| return true; |
| } |
| |
| bool ssl_decode_client_hello_inner( |
| SSL *ssl, uint8_t *out_alert, Array<uint8_t> *out_client_hello_inner, |
| Span<const uint8_t> encoded_client_hello_inner, |
| const SSL_CLIENT_HELLO *client_hello_outer) { |
| SSL_CLIENT_HELLO client_hello_inner; |
| if (!ssl_client_hello_init(ssl, &client_hello_inner, |
| encoded_client_hello_inner)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| // TLS 1.3 ClientHellos must have extensions, and EncodedClientHelloInners use |
| // ClientHelloOuter's session_id. |
| if (client_hello_inner.extensions_len == 0 || |
| client_hello_inner.session_id_len != 0) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| client_hello_inner.session_id = client_hello_outer->session_id; |
| client_hello_inner.session_id_len = client_hello_outer->session_id_len; |
| |
| // Begin serializing a message containing the ClientHelloInner in |cbb|. |
| ScopedCBB cbb; |
| CBB body, extensions; |
| if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CLIENT_HELLO) || |
| !ssl_client_hello_write_without_extensions(&client_hello_inner, &body) || |
| !CBB_add_u16_length_prefixed(&body, &extensions)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return false; |
| } |
| |
| // Sort the extensions in ClientHelloOuter, so ech_outer_extensions may be |
| // processed in O(n*log(n)) time, rather than O(n^2). |
| struct Extension { |
| uint16_t extension = 0; |
| Span<const uint8_t> body; |
| bool copied = false; |
| }; |
| |
| // MSan's libc interceptors do not handle |bsearch|. See b/182583130. |
| auto compare_extension = [](const void *a, const void *b) |
| NO_SANITIZE_MEMORY -> int { |
| const Extension *extension_a = reinterpret_cast<const Extension *>(a); |
| const Extension *extension_b = reinterpret_cast<const Extension *>(b); |
| if (extension_a->extension < extension_b->extension) { |
| return -1; |
| } else if (extension_a->extension > extension_b->extension) { |
| return 1; |
| } |
| return 0; |
| }; |
| GrowableArray<Extension> sorted_extensions; |
| CBS unsorted_extensions(MakeConstSpan(client_hello_outer->extensions, |
| client_hello_outer->extensions_len)); |
| while (CBS_len(&unsorted_extensions) > 0) { |
| Extension extension; |
| CBS extension_body; |
| if (!CBS_get_u16(&unsorted_extensions, &extension.extension) || |
| !CBS_get_u16_length_prefixed(&unsorted_extensions, &extension_body)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return false; |
| } |
| extension.body = extension_body; |
| if (!sorted_extensions.Push(extension)) { |
| return false; |
| } |
| } |
| qsort(sorted_extensions.data(), sorted_extensions.size(), sizeof(Extension), |
| compare_extension); |
| |
| // Copy extensions from |client_hello_inner|, expanding ech_outer_extensions. |
| CBS inner_extensions(MakeConstSpan(client_hello_inner.extensions, |
| client_hello_inner.extensions_len)); |
| while (CBS_len(&inner_extensions) > 0) { |
| uint16_t extension_id; |
| CBS extension_body; |
| if (!CBS_get_u16(&inner_extensions, &extension_id) || |
| !CBS_get_u16_length_prefixed(&inner_extensions, &extension_body)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| if (extension_id != TLSEXT_TYPE_ech_outer_extensions) { |
| if (!CBB_add_u16(&extensions, extension_id) || |
| !CBB_add_u16(&extensions, CBS_len(&extension_body)) || |
| !CBB_add_bytes(&extensions, CBS_data(&extension_body), |
| CBS_len(&extension_body))) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return false; |
| } |
| continue; |
| } |
| |
| // Replace ech_outer_extensions with the corresponding outer extensions. |
| CBS outer_extensions; |
| if (!CBS_get_u8_length_prefixed(&extension_body, &outer_extensions) || |
| CBS_len(&extension_body) != 0) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| while (CBS_len(&outer_extensions) > 0) { |
| uint16_t extension_needed; |
| if (!CBS_get_u16(&outer_extensions, &extension_needed)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| if (extension_needed == TLSEXT_TYPE_encrypted_client_hello) { |
| *out_alert = SSL_AD_ILLEGAL_PARAMETER; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| // Find the referenced extension. |
| Extension key; |
| key.extension = extension_needed; |
| Extension *result = reinterpret_cast<Extension *>( |
| bsearch(&key, sorted_extensions.data(), sorted_extensions.size(), |
| sizeof(Extension), compare_extension)); |
| if (result == nullptr) { |
| *out_alert = SSL_AD_ILLEGAL_PARAMETER; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| |
| // Extensions may be referenced at most once, to bound the result size. |
| if (result->copied) { |
| *out_alert = SSL_AD_ILLEGAL_PARAMETER; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_EXTENSION); |
| return false; |
| } |
| result->copied = true; |
| |
| if (!CBB_add_u16(&extensions, extension_needed) || |
| !CBB_add_u16(&extensions, result->body.size()) || |
| !CBB_add_bytes(&extensions, result->body.data(), |
| result->body.size())) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); |
| return false; |
| } |
| } |
| } |
| if (!CBB_flush(&body)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return false; |
| } |
| |
| // See https://github.com/tlswg/draft-ietf-tls-esni/pull/411 |
| CBS extension; |
| if (!ssl_client_hello_init(ssl, &client_hello_inner, |
| MakeConstSpan(CBB_data(&body), CBB_len(&body))) || |
| !ssl_client_hello_get_extension(&client_hello_inner, &extension, |
| TLSEXT_TYPE_ech_is_inner) || |
| CBS_len(&extension) != 0 || |
| ssl_client_hello_get_extension(&client_hello_inner, &extension, |
| TLSEXT_TYPE_encrypted_client_hello) || |
| !ssl_client_hello_get_extension(&client_hello_inner, &extension, |
| TLSEXT_TYPE_supported_versions)) { |
| *out_alert = SSL_AD_ILLEGAL_PARAMETER; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_CLIENT_HELLO_INNER); |
| return false; |
| } |
| // Parse supported_versions and reject TLS versions prior to TLS 1.3. Older |
| // versions are incompatible with ECH. |
| CBS versions; |
| if (!CBS_get_u8_length_prefixed(&extension, &versions) || |
| CBS_len(&extension) != 0 || // |
| CBS_len(&versions) == 0) { |
| *out_alert = SSL_AD_DECODE_ERROR; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| while (CBS_len(&versions) != 0) { |
| uint16_t version; |
| if (!CBS_get_u16(&versions, &version)) { |
| *out_alert = SSL_AD_DECODE_ERROR; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| if (version == SSL3_VERSION || version == TLS1_VERSION || |
| version == TLS1_1_VERSION || version == TLS1_2_VERSION || |
| version == DTLS1_VERSION || version == DTLS1_2_VERSION) { |
| *out_alert = SSL_AD_ILLEGAL_PARAMETER; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_CLIENT_HELLO_INNER); |
| return false; |
| } |
| } |
| |
| if (!ssl->method->finish_message(ssl, cbb.get(), out_client_hello_inner)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return false; |
| } |
| return true; |
| } |
| |
| bool ssl_client_hello_decrypt( |
| EVP_HPKE_CTX *hpke_ctx, Array<uint8_t> *out_encoded_client_hello_inner, |
| bool *out_is_decrypt_error, const SSL_CLIENT_HELLO *client_hello_outer, |
| uint16_t kdf_id, uint16_t aead_id, Span<const uint8_t> config_id, |
| Span<const uint8_t> enc, Span<const uint8_t> payload) { |
| *out_is_decrypt_error = false; |
| |
| // Compute the ClientHello portion of the ClientHelloOuterAAD value. See |
| // draft-ietf-tls-esni-09, section 5.2. |
| ScopedCBB ch_outer_aad_cbb; |
| CBB config_id_cbb, enc_cbb, outer_hello_cbb, extensions_cbb; |
| if (!CBB_init(ch_outer_aad_cbb.get(), 0) || |
| !CBB_add_u16(ch_outer_aad_cbb.get(), kdf_id) || |
| !CBB_add_u16(ch_outer_aad_cbb.get(), aead_id) || |
| !CBB_add_u8_length_prefixed(ch_outer_aad_cbb.get(), &config_id_cbb) || |
| !CBB_add_bytes(&config_id_cbb, config_id.data(), config_id.size()) || |
| !CBB_add_u16_length_prefixed(ch_outer_aad_cbb.get(), &enc_cbb) || |
| !CBB_add_bytes(&enc_cbb, enc.data(), enc.size()) || |
| !CBB_add_u24_length_prefixed(ch_outer_aad_cbb.get(), &outer_hello_cbb) || |
| !ssl_client_hello_write_without_extensions(client_hello_outer, |
| &outer_hello_cbb) || |
| !CBB_add_u16_length_prefixed(&outer_hello_cbb, &extensions_cbb)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); |
| return false; |
| } |
| |
| CBS extensions(MakeConstSpan(client_hello_outer->extensions, |
| client_hello_outer->extensions_len)); |
| while (CBS_len(&extensions) > 0) { |
| uint16_t extension_id; |
| CBS extension_body; |
| if (!CBS_get_u16(&extensions, &extension_id) || |
| !CBS_get_u16_length_prefixed(&extensions, &extension_body)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| if (extension_id == TLSEXT_TYPE_encrypted_client_hello) { |
| continue; |
| } |
| if (!CBB_add_u16(&extensions_cbb, extension_id) || |
| !CBB_add_u16(&extensions_cbb, CBS_len(&extension_body)) || |
| !CBB_add_bytes(&extensions_cbb, CBS_data(&extension_body), |
| CBS_len(&extension_body))) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); |
| return false; |
| } |
| } |
| if (!CBB_flush(ch_outer_aad_cbb.get())) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); |
| return false; |
| } |
| |
| // Attempt to decrypt into |out_encoded_client_hello_inner|. |
| if (!out_encoded_client_hello_inner->Init(payload.size())) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); |
| return false; |
| } |
| size_t encoded_client_hello_inner_len; |
| if (!EVP_HPKE_CTX_open(hpke_ctx, out_encoded_client_hello_inner->data(), |
| &encoded_client_hello_inner_len, |
| out_encoded_client_hello_inner->size(), payload.data(), |
| payload.size(), CBB_data(ch_outer_aad_cbb.get()), |
| CBB_len(ch_outer_aad_cbb.get()))) { |
| *out_is_decrypt_error = true; |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED); |
| return false; |
| } |
| out_encoded_client_hello_inner->Shrink(encoded_client_hello_inner_len); |
| return true; |
| } |
| |
| |
| bool ECHServerConfig::Init(Span<const uint8_t> raw, |
| Span<const uint8_t> private_key, |
| bool is_retry_config) { |
| assert(!initialized_); |
| is_retry_config_ = is_retry_config; |
| |
| if (!raw_.CopyFrom(raw)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); |
| return false; |
| } |
| // Read from |raw_| so we can save Spans with the same lifetime as |this|. |
| CBS reader(raw_); |
| |
| uint16_t version; |
| if (!CBS_get_u16(&reader, &version)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| // Parse the ECHConfig, rejecting all unsupported parameters and extensions. |
| // Unlike most server options, ECH's server configuration is serialized and |
| // configured in both the server and DNS. If the caller configures an |
| // unsupported parameter, this is a deployment error. To catch these errors, |
| // we fail early. |
| if (version != TLSEXT_TYPE_encrypted_client_hello) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_ECH_SERVER_CONFIG); |
| return false; |
| } |
| |
| CBS ech_config_contents, public_name, public_key, cipher_suites, extensions; |
| uint16_t kem_id, max_name_len; |
| if (!CBS_get_u16_length_prefixed(&reader, &ech_config_contents) || |
| !CBS_get_u16_length_prefixed(&ech_config_contents, &public_name) || |
| CBS_len(&public_name) == 0 || |
| !CBS_get_u16_length_prefixed(&ech_config_contents, &public_key) || |
| CBS_len(&public_key) == 0 || |
| !CBS_get_u16(&ech_config_contents, &kem_id) || |
| !CBS_get_u16_length_prefixed(&ech_config_contents, &cipher_suites) || |
| CBS_len(&cipher_suites) == 0 || |
| !CBS_get_u16(&ech_config_contents, &max_name_len) || |
| !CBS_get_u16_length_prefixed(&ech_config_contents, &extensions) || |
| CBS_len(&ech_config_contents) != 0 || // |
| CBS_len(&reader) != 0) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| // We only support one KEM, and the KEM decides the length of |public_key|. |
| if (CBS_len(&public_key) != X25519_PUBLIC_VALUE_LEN || |
| kem_id != EVP_HPKE_DHKEM_X25519_HKDF_SHA256) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_ECH_SERVER_CONFIG); |
| return false; |
| } |
| public_key_ = public_key; |
| |
| // We do not support any ECHConfig extensions, so |extensions| must be empty. |
| if (CBS_len(&extensions) != 0) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_ECH_SERVER_CONFIG_UNSUPPORTED_EXTENSION); |
| return false; |
| } |
| |
| cipher_suites_ = cipher_suites; |
| while (CBS_len(&cipher_suites) > 0) { |
| uint16_t kdf_id, aead_id; |
| if (!CBS_get_u16(&cipher_suites, &kdf_id) || |
| !CBS_get_u16(&cipher_suites, &aead_id)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| // This parser fails when it encounters any bytes it does not understand. If |
| // the config lists any unsupported cipher suites, that is a parse error. |
| if (kdf_id != EVP_HPKE_HKDF_SHA256 || |
| (aead_id != EVP_HPKE_AEAD_AES_128_GCM && |
| aead_id != EVP_HPKE_AEAD_AES_256_GCM && |
| aead_id != EVP_HPKE_AEAD_CHACHA20POLY1305)) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_ECH_SERVER_CONFIG); |
| return false; |
| } |
| } |
| |
| // Precompute the config_id. |
| uint8_t key[EVP_MAX_KEY_LENGTH]; |
| size_t key_len; |
| static const uint8_t kInfo[] = "tls ech config id"; |
| if (!HKDF_extract(key, &key_len, EVP_sha256(), raw_.data(), raw_.size(), |
| nullptr, 0) || |
| !HKDF_expand(config_id_sha256_, sizeof(config_id_sha256_), EVP_sha256(), |
| key, key_len, kInfo, OPENSSL_ARRAY_SIZE(kInfo) - 1)) { |
| OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); |
| return false; |
| } |
| |
| if (private_key.size() != X25519_PRIVATE_KEY_LEN) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); |
| return false; |
| } |
| uint8_t expected_public_key[X25519_PUBLIC_VALUE_LEN]; |
| X25519_public_from_private(expected_public_key, private_key.data()); |
| if (public_key_ != expected_public_key) { |
| OPENSSL_PUT_ERROR(SSL, SSL_R_ECH_SERVER_CONFIG_AND_PRIVATE_KEY_MISMATCH); |
| return false; |
| } |
| assert(sizeof(private_key_) == private_key.size()); |
| OPENSSL_memcpy(private_key_, private_key.data(), private_key.size()); |
| |
| initialized_ = true; |
| return true; |
| } |
| |
| bool ECHServerConfig::SupportsCipherSuite(uint16_t kdf_id, |
| uint16_t aead_id) const { |
| assert(initialized_); |
| CBS cbs(cipher_suites_); |
| while (CBS_len(&cbs) != 0) { |
| uint16_t supported_kdf_id, supported_aead_id; |
| if (!CBS_get_u16(&cbs, &supported_kdf_id) || |
| !CBS_get_u16(&cbs, &supported_aead_id)) { |
| return false; |
| } |
| if (kdf_id == supported_kdf_id && aead_id == supported_aead_id) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| BSSL_NAMESPACE_END |
