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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
/* ====================================================================
* Copyright (c) 1998-2007 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/ssl.h>
#include <assert.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include <utility>
#include <openssl/aead.h>
#include <openssl/bytestring.h>
#include <openssl/chacha.h>
#include <openssl/curve25519.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/mem.h>
#include <openssl/nid.h>
#include <openssl/rand.h>
#include "../crypto/hpke/internal.h"
#include "../crypto/internal.h"
#include "internal.h"
BSSL_NAMESPACE_BEGIN
static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs);
static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs);
static int compare_uint16_t(const void *p1, const void *p2) {
uint16_t u1 = *((const uint16_t *)p1);
uint16_t u2 = *((const uint16_t *)p2);
if (u1 < u2) {
return -1;
} else if (u1 > u2) {
return 1;
} else {
return 0;
}
}
// Per http://tools.ietf.org/html/rfc5246#section-7.4.1.4, there may not be
// more than one extension of the same type in a ClientHello or ServerHello.
// This function does an initial scan over the extensions block to filter those
// out.
static bool tls1_check_duplicate_extensions(const CBS *cbs) {
// First pass: count the extensions.
size_t num_extensions = 0;
CBS extensions = *cbs;
while (CBS_len(&extensions) > 0) {
uint16_t type;
CBS extension;
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
return false;
}
num_extensions++;
}
if (num_extensions == 0) {
return true;
}
Array<uint16_t> extension_types;
if (!extension_types.Init(num_extensions)) {
return false;
}
// Second pass: gather the extension types.
extensions = *cbs;
for (size_t i = 0; i < extension_types.size(); i++) {
CBS extension;
if (!CBS_get_u16(&extensions, &extension_types[i]) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
// This should not happen.
return false;
}
}
assert(CBS_len(&extensions) == 0);
// Sort the extensions and make sure there are no duplicates.
qsort(extension_types.data(), extension_types.size(), sizeof(uint16_t),
compare_uint16_t);
for (size_t i = 1; i < num_extensions; i++) {
if (extension_types[i - 1] == extension_types[i]) {
return false;
}
}
return true;
}
static bool is_post_quantum_group(uint16_t id) {
return id == SSL_CURVE_CECPQ2;
}
bool ssl_client_hello_init(const SSL *ssl, SSL_CLIENT_HELLO *out,
const SSLMessage &msg) {
OPENSSL_memset(out, 0, sizeof(*out));
out->ssl = const_cast<SSL *>(ssl);
out->client_hello = CBS_data(&msg.body);
out->client_hello_len = CBS_len(&msg.body);
CBS client_hello, random, session_id;
CBS_init(&client_hello, out->client_hello, out->client_hello_len);
if (!CBS_get_u16(&client_hello, &out->version) ||
!CBS_get_bytes(&client_hello, &random, SSL3_RANDOM_SIZE) ||
!CBS_get_u8_length_prefixed(&client_hello, &session_id) ||
CBS_len(&session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH) {
return false;
}
out->random = CBS_data(&random);
out->random_len = CBS_len(&random);
out->session_id = CBS_data(&session_id);
out->session_id_len = CBS_len(&session_id);
// Skip past DTLS cookie
if (SSL_is_dtls(out->ssl)) {
CBS cookie;
if (!CBS_get_u8_length_prefixed(&client_hello, &cookie) ||
CBS_len(&cookie) > DTLS1_COOKIE_LENGTH) {
return false;
}
}
CBS cipher_suites, compression_methods;
if (!CBS_get_u16_length_prefixed(&client_hello, &cipher_suites) ||
CBS_len(&cipher_suites) < 2 || (CBS_len(&cipher_suites) & 1) != 0 ||
!CBS_get_u8_length_prefixed(&client_hello, &compression_methods) ||
CBS_len(&compression_methods) < 1) {
return false;
}
out->cipher_suites = CBS_data(&cipher_suites);
out->cipher_suites_len = CBS_len(&cipher_suites);
out->compression_methods = CBS_data(&compression_methods);
out->compression_methods_len = CBS_len(&compression_methods);
// If the ClientHello ends here then it's valid, but doesn't have any
// extensions.
if (CBS_len(&client_hello) == 0) {
out->extensions = NULL;
out->extensions_len = 0;
return true;
}
// Extract extensions and check it is valid.
CBS extensions;
if (!CBS_get_u16_length_prefixed(&client_hello, &extensions) ||
!tls1_check_duplicate_extensions(&extensions) ||
CBS_len(&client_hello) != 0) {
return false;
}
out->extensions = CBS_data(&extensions);
out->extensions_len = CBS_len(&extensions);
return true;
}
bool ssl_client_hello_get_extension(const SSL_CLIENT_HELLO *client_hello,
CBS *out, uint16_t extension_type) {
CBS extensions;
CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len);
while (CBS_len(&extensions) != 0) {
// Decode the next extension.
uint16_t type;
CBS extension;
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
return false;
}
if (type == extension_type) {
*out = extension;
return true;
}
}
return false;
}
static const uint16_t kDefaultGroups[] = {
SSL_CURVE_X25519,
SSL_CURVE_SECP256R1,
SSL_CURVE_SECP384R1,
};
Span<const uint16_t> tls1_get_grouplist(const SSL_HANDSHAKE *hs) {
if (!hs->config->supported_group_list.empty()) {
return hs->config->supported_group_list;
}
return Span<const uint16_t>(kDefaultGroups);
}
bool tls1_get_shared_group(SSL_HANDSHAKE *hs, uint16_t *out_group_id) {
SSL *const ssl = hs->ssl;
assert(ssl->server);
// Clients are not required to send a supported_groups extension. In this
// case, the server is free to pick any group it likes. See RFC 4492,
// section 4, paragraph 3.
//
// However, in the interests of compatibility, we will skip ECDH if the
// client didn't send an extension because we can't be sure that they'll
// support our favoured group. Thus we do not special-case an emtpy
// |peer_supported_group_list|.
Span<const uint16_t> groups = tls1_get_grouplist(hs);
Span<const uint16_t> pref, supp;
if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) {
pref = groups;
supp = hs->peer_supported_group_list;
} else {
pref = hs->peer_supported_group_list;
supp = groups;
}
for (uint16_t pref_group : pref) {
for (uint16_t supp_group : supp) {
if (pref_group == supp_group &&
// CECPQ2(b) doesn't fit in the u8-length-prefixed ECPoint field in
// TLS 1.2 and below.
(ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
!is_post_quantum_group(pref_group))) {
*out_group_id = pref_group;
return true;
}
}
}
return false;
}
bool tls1_set_curves(Array<uint16_t> *out_group_ids, Span<const int> curves) {
Array<uint16_t> group_ids;
if (!group_ids.Init(curves.size())) {
return false;
}
for (size_t i = 0; i < curves.size(); i++) {
if (!ssl_nid_to_group_id(&group_ids[i], curves[i])) {
return false;
}
}
*out_group_ids = std::move(group_ids);
return true;
}
bool tls1_set_curves_list(Array<uint16_t> *out_group_ids, const char *curves) {
// Count the number of curves in the list.
size_t count = 0;
const char *ptr = curves, *col;
do {
col = strchr(ptr, ':');
count++;
if (col) {
ptr = col + 1;
}
} while (col);
Array<uint16_t> group_ids;
if (!group_ids.Init(count)) {
return false;
}
size_t i = 0;
ptr = curves;
do {
col = strchr(ptr, ':');
if (!ssl_name_to_group_id(&group_ids[i++], ptr,
col ? (size_t)(col - ptr) : strlen(ptr))) {
return false;
}
if (col) {
ptr = col + 1;
}
} while (col);
assert(i == count);
*out_group_ids = std::move(group_ids);
return true;
}
bool tls1_check_group_id(const SSL_HANDSHAKE *hs, uint16_t group_id) {
if (is_post_quantum_group(group_id) &&
ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
// CECPQ2(b) requires TLS 1.3.
return false;
}
for (uint16_t supported : tls1_get_grouplist(hs)) {
if (supported == group_id) {
return true;
}
}
return false;
}
// kVerifySignatureAlgorithms is the default list of accepted signature
// algorithms for verifying.
static const uint16_t kVerifySignatureAlgorithms[] = {
// List our preferred algorithms first.
SSL_SIGN_ECDSA_SECP256R1_SHA256,
SSL_SIGN_RSA_PSS_RSAE_SHA256,
SSL_SIGN_RSA_PKCS1_SHA256,
// Larger hashes are acceptable.
SSL_SIGN_ECDSA_SECP384R1_SHA384,
SSL_SIGN_RSA_PSS_RSAE_SHA384,
SSL_SIGN_RSA_PKCS1_SHA384,
SSL_SIGN_RSA_PSS_RSAE_SHA512,
SSL_SIGN_RSA_PKCS1_SHA512,
// For now, SHA-1 is still accepted but least preferable.
SSL_SIGN_RSA_PKCS1_SHA1,
};
// kSignSignatureAlgorithms is the default list of supported signature
// algorithms for signing.
static const uint16_t kSignSignatureAlgorithms[] = {
// List our preferred algorithms first.
SSL_SIGN_ED25519,
SSL_SIGN_ECDSA_SECP256R1_SHA256,
SSL_SIGN_RSA_PSS_RSAE_SHA256,
SSL_SIGN_RSA_PKCS1_SHA256,
// If needed, sign larger hashes.
//
// TODO(davidben): Determine which of these may be pruned.
SSL_SIGN_ECDSA_SECP384R1_SHA384,
SSL_SIGN_RSA_PSS_RSAE_SHA384,
SSL_SIGN_RSA_PKCS1_SHA384,
SSL_SIGN_ECDSA_SECP521R1_SHA512,
SSL_SIGN_RSA_PSS_RSAE_SHA512,
SSL_SIGN_RSA_PKCS1_SHA512,
// If the peer supports nothing else, sign with SHA-1.
SSL_SIGN_ECDSA_SHA1,
SSL_SIGN_RSA_PKCS1_SHA1,
};
static Span<const uint16_t> tls12_get_verify_sigalgs(const SSL_HANDSHAKE *hs) {
if (hs->config->verify_sigalgs.empty()) {
return Span<const uint16_t>(kVerifySignatureAlgorithms);
}
return hs->config->verify_sigalgs;
}
bool tls12_add_verify_sigalgs(const SSL_HANDSHAKE *hs, CBB *out) {
for (uint16_t sigalg : tls12_get_verify_sigalgs(hs)) {
if (!CBB_add_u16(out, sigalg)) {
return false;
}
}
return true;
}
bool tls12_check_peer_sigalg(const SSL_HANDSHAKE *hs, uint8_t *out_alert,
uint16_t sigalg) {
for (uint16_t verify_sigalg : tls12_get_verify_sigalgs(hs)) {
if (verify_sigalg == sigalg) {
return true;
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// tls_extension represents a TLS extension that is handled internally. The
// |init| function is called for each handshake, before any other functions of
// the extension. Then the add and parse callbacks are called as needed.
//
// The parse callbacks receive a |CBS| that contains the contents of the
// extension (i.e. not including the type and length bytes). If an extension is
// not received then the parse callbacks will be called with a NULL CBS so that
// they can do any processing needed to handle the absence of an extension.
//
// The add callbacks receive a |CBB| to which the extension can be appended but
// the function is responsible for appending the type and length bytes too.
//
// All callbacks return true for success and false for error. If a parse
// function returns zero then a fatal alert with value |*out_alert| will be
// sent. If |*out_alert| isn't set, then a |decode_error| alert will be sent.
struct tls_extension {
uint16_t value;
void (*init)(SSL_HANDSHAKE *hs);
bool (*add_clienthello)(SSL_HANDSHAKE *hs, CBB *out);
bool (*parse_serverhello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents);
bool (*parse_clienthello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents);
bool (*add_serverhello)(SSL_HANDSHAKE *hs, CBB *out);
};
static bool forbid_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents != NULL) {
// Servers MUST NOT send this extension.
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
return false;
}
return true;
}
static bool ignore_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
// This extension from the client is handled elsewhere.
return true;
}
static bool dont_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
return true;
}
// Server name indication (SNI).
//
// https://tools.ietf.org/html/rfc6066#section-3.
static bool ext_sni_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->hostname == nullptr) {
return true;
}
CBB contents, server_name_list, name;
if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &server_name_list) ||
!CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name) ||
!CBB_add_u16_length_prefixed(&server_name_list, &name) ||
!CBB_add_bytes(&name, (const uint8_t *)ssl->hostname.get(),
strlen(ssl->hostname.get())) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_sni_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
// The server may acknowledge SNI with an empty extension. We check the syntax
// but otherwise ignore this signal.
return contents == NULL || CBS_len(contents) == 0;
}
static bool ext_sni_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
// SNI has already been parsed earlier in the handshake. See |extract_sni|.
return true;
}
static bool ext_sni_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->ssl->s3->session_reused ||
!hs->should_ack_sni) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Encrypted Client Hello (ECH)
//
// https://tools.ietf.org/html/draft-ietf-tls-esni-08
// random_size returns a random value between |min| and |max|, inclusive.
static size_t random_size(size_t min, size_t max) {
assert(min < max);
size_t value;
RAND_bytes(reinterpret_cast<uint8_t *>(&value), sizeof(value));
return value % (max - min + 1) + min;
}
static bool ext_ech_add_clienthello_grease(SSL_HANDSHAKE *hs, CBB *out) {
// If we are responding to the server's HelloRetryRequest, we repeat the bytes
// of the first ECH GREASE extension.
if (hs->ssl->s3->used_hello_retry_request) {
CBB ech_body;
if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
!CBB_add_u16_length_prefixed(out, &ech_body) ||
!CBB_add_bytes(&ech_body, hs->ech_grease.data(),
hs->ech_grease.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
constexpr uint16_t kdf_id = EVP_HPKE_HKDF_SHA256;
const EVP_MD *kdf = EVP_HPKE_get_hkdf_md(kdf_id);
assert(kdf != nullptr);
const uint16_t aead_id = EVP_has_aes_hardware()
? EVP_HPKE_AEAD_AES_GCM_128
: EVP_HPKE_AEAD_CHACHA20POLY1305;
const EVP_AEAD *aead = EVP_HPKE_get_aead(aead_id);
assert(aead != nullptr);
uint8_t ech_config_id_buf[EVP_MAX_MD_SIZE];
Span<uint8_t> ech_config_id(ech_config_id_buf, EVP_MD_size(kdf));
RAND_bytes(ech_config_id.data(), ech_config_id.size());
uint8_t ech_enc[X25519_PUBLIC_VALUE_LEN];
uint8_t private_key_unused[X25519_PRIVATE_KEY_LEN];
X25519_keypair(ech_enc, private_key_unused);
// To determine a plausible length for the payload, we first estimate the size
// of a typical EncodedClientHelloInner, with an expected use of
// outer_extensions. To limit the size, we only consider initial ClientHellos
// that do not offer resumption.
//
// Field/Extension Size
// ---------------------------------------------------------------------
// version 2
// random 32
// legacy_session_id 1
// - Has a U8 length prefix, but body is
// always empty string in inner CH.
// cipher_suites 2 (length prefix)
// - Only includes TLS 1.3 ciphers (3). 6
// - Maybe also include a GREASE suite. 2
// legacy_compression_methods 2 (length prefix)
// - Always has "null" compression method. 1
// extensions: 2 (length prefix)
// - encrypted_client_hello (empty). 4 (id + length prefix)
// - supported_versions. 4 (id + length prefix)
// - U8 length prefix 1
// - U16 protocol version (TLS 1.3) 2
// - outer_extensions. 4 (id + length prefix)
// - U8 length prefix 1
// - N extension IDs (2 bytes each):
// - key_share 2
// - sigalgs 2
// - sct 2
// - alpn 2
// - supported_groups. 2
// - status_request. 2
// - psk_key_exchange_modes. 2
// - compress_certificate. 2
//
// The server_name extension has an overhead of 9 bytes, plus up to an
// estimated 100 bytes of hostname. Rounding up to a multiple of 32 yields a
// range of 96 to 192. Note that this estimate does not fully capture
// optional extensions like GREASE, but the rounding gives some leeway.
uint8_t payload[EVP_AEAD_MAX_OVERHEAD + 192];
const size_t payload_len =
EVP_AEAD_max_overhead(aead) + 32 * random_size(96 / 32, 192 / 32);
assert(payload_len <= sizeof(payload));
RAND_bytes(payload, payload_len);
// Inside the TLS extension contents, write a serialized ClientEncryptedCH.
CBB ech_body, config_id_cbb, enc_cbb, payload_cbb;
if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
!CBB_add_u16_length_prefixed(out, &ech_body) ||
!CBB_add_u16(&ech_body, kdf_id) || //
!CBB_add_u16(&ech_body, aead_id) ||
!CBB_add_u8_length_prefixed(&ech_body, &config_id_cbb) ||
!CBB_add_bytes(&config_id_cbb, ech_config_id.data(),
ech_config_id.size()) ||
!CBB_add_u16_length_prefixed(&ech_body, &enc_cbb) ||
!CBB_add_bytes(&enc_cbb, ech_enc, OPENSSL_ARRAY_SIZE(ech_enc)) ||
!CBB_add_u16_length_prefixed(&ech_body, &payload_cbb) ||
!CBB_add_bytes(&payload_cbb, payload, payload_len) || //
!CBB_flush(&ech_body)) {
return false;
}
// Save the bytes of the newly-generated extension in case the server sends
// a HelloRetryRequest.
if (!hs->ech_grease.CopyFrom(
MakeConstSpan(CBB_data(&ech_body), CBB_len(&ech_body)))) {
return false;
}
return CBB_flush(out);
}
static bool ext_ech_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->max_version < TLS1_3_VERSION) {
return true;
}
if (hs->config->ech_grease_enabled) {
return ext_ech_add_clienthello_grease(hs, out);
}
// Nothing to do, since we don't yet implement the non-GREASE parts of ECH.
return true;
}
static bool ext_ech_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
// If the client only sent GREASE, we must check the extension syntactically.
CBS ech_configs;
if (!CBS_get_u16_length_prefixed(contents, &ech_configs) ||
CBS_len(&ech_configs) == 0 || //
CBS_len(contents) > 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
while (CBS_len(&ech_configs) > 0) {
// Do a top-level parse of the ECHConfig, stopping before ECHConfigContents.
uint16_t version;
CBS ech_config_contents;
if (!CBS_get_u16(&ech_configs, &version) ||
!CBS_get_u16_length_prefixed(&ech_configs, &ech_config_contents)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
}
return true;
}
// Renegotiation indication.
//
// https://tools.ietf.org/html/rfc5746
static bool ext_ri_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// Renegotiation indication is not necessary in TLS 1.3.
if (hs->min_version >= TLS1_3_VERSION) {
return true;
}
assert(ssl->s3->initial_handshake_complete ==
(ssl->s3->previous_client_finished_len != 0));
CBB contents, prev_finished;
if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &prev_finished) ||
!CBB_add_bytes(&prev_finished, ssl->s3->previous_client_finished,
ssl->s3->previous_client_finished_len) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ri_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents != NULL && ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// Servers may not switch between omitting the extension and supporting it.
// See RFC 5746, sections 3.5 and 4.2.
if (ssl->s3->initial_handshake_complete &&
(contents != NULL) != ssl->s3->send_connection_binding) {
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
return false;
}
if (contents == NULL) {
// Strictly speaking, if we want to avoid an attack we should *always* see
// RI even on initial ServerHello because the client doesn't see any
// renegotiation during an attack. However this would mean we could not
// connect to any server which doesn't support RI.
//
// OpenSSL has |SSL_OP_LEGACY_SERVER_CONNECT| to control this, but in
// practical terms every client sets it so it's just assumed here.
return true;
}
const size_t expected_len = ssl->s3->previous_client_finished_len +
ssl->s3->previous_server_finished_len;
// Check for logic errors
assert(!expected_len || ssl->s3->previous_client_finished_len);
assert(!expected_len || ssl->s3->previous_server_finished_len);
assert(ssl->s3->initial_handshake_complete ==
(ssl->s3->previous_client_finished_len != 0));
assert(ssl->s3->initial_handshake_complete ==
(ssl->s3->previous_server_finished_len != 0));
// Parse out the extension contents.
CBS renegotiated_connection;
if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// Check that the extension matches.
if (CBS_len(&renegotiated_connection) != expected_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
const uint8_t *d = CBS_data(&renegotiated_connection);
bool ok = CRYPTO_memcmp(d, ssl->s3->previous_client_finished,
ssl->s3->previous_client_finished_len) == 0;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
ok = true;
#endif
if (!ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
d += ssl->s3->previous_client_finished_len;
ok = CRYPTO_memcmp(d, ssl->s3->previous_server_finished,
ssl->s3->previous_server_finished_len) == 0;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
ok = true;
#endif
if (!ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
ssl->s3->send_connection_binding = true;
return true;
}
static bool ext_ri_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
// Renegotiation isn't supported as a server so this function should never be
// called after the initial handshake.
assert(!ssl->s3->initial_handshake_complete);
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
if (contents == NULL) {
return true;
}
CBS renegotiated_connection;
if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR);
return false;
}
// Check that the extension matches. We do not support renegotiation as a
// server, so this must be empty.
if (CBS_len(&renegotiated_connection) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
ssl->s3->send_connection_binding = true;
return true;
}
static bool ext_ri_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// Renegotiation isn't supported as a server so this function should never be
// called after the initial handshake.
assert(!ssl->s3->initial_handshake_complete);
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
!CBB_add_u16(out, 1 /* length */) ||
!CBB_add_u8(out, 0 /* empty renegotiation info */)) {
return false;
}
return true;
}
// Extended Master Secret.
//
// https://tools.ietf.org/html/rfc7627
static bool ext_ems_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
// Extended master secret is not necessary in TLS 1.3.
if (hs->min_version >= TLS1_3_VERSION) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_ems_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents != NULL) {
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
CBS_len(contents) != 0) {
return false;
}
hs->extended_master_secret = true;
}
// Whether EMS is negotiated may not change on renegotiation.
if (ssl->s3->established_session != nullptr &&
hs->extended_master_secret !=
!!ssl->s3->established_session->extended_master_secret) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_EMS_MISMATCH);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
return true;
}
static bool ext_ems_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return true;
}
if (contents == NULL) {
return true;
}
if (CBS_len(contents) != 0) {
return false;
}
hs->extended_master_secret = true;
return true;
}
static bool ext_ems_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->extended_master_secret) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Session tickets.
//
// https://tools.ietf.org/html/rfc5077
static bool ext_ticket_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// TLS 1.3 uses a different ticket extension.
if (hs->min_version >= TLS1_3_VERSION ||
SSL_get_options(ssl) & SSL_OP_NO_TICKET) {
return true;
}
Span<const uint8_t> ticket;
// Renegotiation does not participate in session resumption. However, still
// advertise the extension to avoid potentially breaking servers which carry
// over the state from the previous handshake, such as OpenSSL servers
// without upstream's 3c3f0259238594d77264a78944d409f2127642c4.
if (!ssl->s3->initial_handshake_complete &&
ssl->session != nullptr &&
!ssl->session->ticket.empty() &&
// Don't send TLS 1.3 session tickets in the ticket extension.
ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) {
ticket = ssl->session->ticket;
}
CBB ticket_cbb;
if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
!CBB_add_u16_length_prefixed(out, &ticket_cbb) ||
!CBB_add_bytes(&ticket_cbb, ticket.data(), ticket.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ticket_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return false;
}
// If |SSL_OP_NO_TICKET| is set then no extension will have been sent and
// this function should never be called, even if the server tries to send the
// extension.
assert((SSL_get_options(ssl) & SSL_OP_NO_TICKET) == 0);
if (CBS_len(contents) != 0) {
return false;
}
hs->ticket_expected = true;
return true;
}
static bool ext_ticket_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ticket_expected) {
return true;
}
// If |SSL_OP_NO_TICKET| is set, |ticket_expected| should never be true.
assert((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) == 0);
if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Signature Algorithms.
//
// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
static bool ext_sigalgs_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->max_version < TLS1_2_VERSION) {
return true;
}
CBB contents, sigalgs_cbb;
if (!CBB_add_u16(out, TLSEXT_TYPE_signature_algorithms) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &sigalgs_cbb) ||
!tls12_add_verify_sigalgs(hs, &sigalgs_cbb) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_sigalgs_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
hs->peer_sigalgs.Reset();
if (contents == NULL) {
return true;
}
CBS supported_signature_algorithms;
if (!CBS_get_u16_length_prefixed(contents, &supported_signature_algorithms) ||
CBS_len(contents) != 0 ||
!tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) {
return false;
}
return true;
}
// OCSP Stapling.
//
// https://tools.ietf.org/html/rfc6066#section-8
static bool ext_ocsp_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->config->ocsp_stapling_enabled) {
return true;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_status_request) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) ||
!CBB_add_u16(&contents, 0 /* empty responder ID list */) ||
!CBB_add_u16(&contents, 0 /* empty request extensions */) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ocsp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// TLS 1.3 OCSP responses are included in the Certificate extensions.
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return false;
}
// OCSP stapling is forbidden on non-certificate ciphers.
if (CBS_len(contents) != 0 ||
!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
return false;
}
// Note this does not check for resumption in TLS 1.2. Sending
// status_request here does not make sense, but OpenSSL does so and the
// specification does not say anything. Tolerate it but ignore it.
hs->certificate_status_expected = true;
return true;
}
static bool ext_ocsp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
uint8_t status_type;
if (!CBS_get_u8(contents, &status_type)) {
return false;
}
// We cannot decide whether OCSP stapling will occur yet because the correct
// SSL_CTX might not have been selected.
hs->ocsp_stapling_requested = status_type == TLSEXT_STATUSTYPE_ocsp;
return true;
}
static bool ext_ocsp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
!hs->ocsp_stapling_requested || hs->config->cert->ocsp_response == NULL ||
ssl->s3->session_reused ||
!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
return true;
}
hs->certificate_status_expected = true;
return CBB_add_u16(out, TLSEXT_TYPE_status_request) &&
CBB_add_u16(out, 0 /* length */);
}
// Next protocol negotiation.
//
// https://htmlpreview.github.io/?https://github.com/agl/technotes/blob/master/nextprotoneg.html
static bool ext_npn_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->s3->initial_handshake_complete ||
ssl->ctx->next_proto_select_cb == NULL ||
SSL_is_dtls(ssl)) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_npn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return false;
}
// If any of these are false then we should never have sent the NPN
// extension in the ClientHello and thus this function should never have been
// called.
assert(!ssl->s3->initial_handshake_complete);
assert(!SSL_is_dtls(ssl));
assert(ssl->ctx->next_proto_select_cb != NULL);
if (!ssl->s3->alpn_selected.empty()) {
// NPN and ALPN may not be negotiated in the same connection.
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN);
return false;
}
const uint8_t *const orig_contents = CBS_data(contents);
const size_t orig_len = CBS_len(contents);
while (CBS_len(contents) != 0) {
CBS proto;
if (!CBS_get_u8_length_prefixed(contents, &proto) ||
CBS_len(&proto) == 0) {
return false;
}
}
uint8_t *selected;
uint8_t selected_len;
if (ssl->ctx->next_proto_select_cb(
ssl, &selected, &selected_len, orig_contents, orig_len,
ssl->ctx->next_proto_select_cb_arg) != SSL_TLSEXT_ERR_OK ||
!ssl->s3->next_proto_negotiated.CopyFrom(
MakeConstSpan(selected, selected_len))) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
hs->next_proto_neg_seen = true;
return true;
}
static bool ext_npn_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
if (contents != NULL && CBS_len(contents) != 0) {
return false;
}
if (contents == NULL ||
ssl->s3->initial_handshake_complete ||
ssl->ctx->next_protos_advertised_cb == NULL ||
SSL_is_dtls(ssl)) {
return true;
}
hs->next_proto_neg_seen = true;
return true;
}
static bool ext_npn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// |next_proto_neg_seen| might have been cleared when an ALPN extension was
// parsed.
if (!hs->next_proto_neg_seen) {
return true;
}
const uint8_t *npa;
unsigned npa_len;
if (ssl->ctx->next_protos_advertised_cb(
ssl, &npa, &npa_len, ssl->ctx->next_protos_advertised_cb_arg) !=
SSL_TLSEXT_ERR_OK) {
hs->next_proto_neg_seen = false;
return true;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents, npa, npa_len) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Signed certificate timestamps.
//
// https://tools.ietf.org/html/rfc6962#section-3.3.1
static bool ext_sct_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->config->signed_cert_timestamps_enabled) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_sct_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// TLS 1.3 SCTs are included in the Certificate extensions.
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// If this is false then we should never have sent the SCT extension in the
// ClientHello and thus this function should never have been called.
assert(hs->config->signed_cert_timestamps_enabled);
if (!ssl_is_sct_list_valid(contents)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// Session resumption uses the original session information. The extension
// should not be sent on resumption, but RFC 6962 did not make it a
// requirement, so tolerate this.
//
// TODO(davidben): Enforce this anyway.
if (!ssl->s3->session_reused) {
hs->new_session->signed_cert_timestamp_list.reset(
CRYPTO_BUFFER_new_from_CBS(contents, ssl->ctx->pool));
if (hs->new_session->signed_cert_timestamp_list == nullptr) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
}
return true;
}
static bool ext_sct_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
if (CBS_len(contents) != 0) {
return false;
}
hs->scts_requested = true;
return true;
}
static bool ext_sct_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// The extension shouldn't be sent when resuming sessions.
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION || ssl->s3->session_reused ||
hs->config->cert->signed_cert_timestamp_list == NULL) {
return true;
}
CBB contents;
return CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) &&
CBB_add_u16_length_prefixed(out, &contents) &&
CBB_add_bytes(
&contents,
CRYPTO_BUFFER_data(
hs->config->cert->signed_cert_timestamp_list.get()),
CRYPTO_BUFFER_len(
hs->config->cert->signed_cert_timestamp_list.get())) &&
CBB_flush(out);
}
// Application-level Protocol Negotiation.
//
// https://tools.ietf.org/html/rfc7301
static bool ext_alpn_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (hs->config->alpn_client_proto_list.empty() && ssl->quic_method) {
// ALPN MUST be used with QUIC.
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_ALPN);
return false;
}
if (hs->config->alpn_client_proto_list.empty() ||
ssl->s3->initial_handshake_complete) {
return true;
}
CBB contents, proto_list;
if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &proto_list) ||
!CBB_add_bytes(&proto_list, hs->config->alpn_client_proto_list.data(),
hs->config->alpn_client_proto_list.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_alpn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
if (ssl->quic_method) {
// ALPN is required when QUIC is used.
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_ALPN);
*out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
return false;
}
return true;
}
assert(!ssl->s3->initial_handshake_complete);
assert(!hs->config->alpn_client_proto_list.empty());
if (hs->next_proto_neg_seen) {
// NPN and ALPN may not be negotiated in the same connection.
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN);
return false;
}
// The extension data consists of a ProtocolNameList which must have
// exactly one ProtocolName. Each of these is length-prefixed.
CBS protocol_name_list, protocol_name;
if (!CBS_get_u16_length_prefixed(contents, &protocol_name_list) ||
CBS_len(contents) != 0 ||
!CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) ||
// Empty protocol names are forbidden.
CBS_len(&protocol_name) == 0 ||
CBS_len(&protocol_name_list) != 0) {
return false;
}
if (!ssl_is_alpn_protocol_allowed(hs, protocol_name)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
if (!ssl->s3->alpn_selected.CopyFrom(protocol_name)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
return true;
}
bool ssl_is_alpn_protocol_allowed(const SSL_HANDSHAKE *hs,
Span<const uint8_t> protocol) {
if (hs->config->alpn_client_proto_list.empty()) {
return false;
}
if (hs->ssl->ctx->allow_unknown_alpn_protos) {
return true;
}
// Check that the protocol name is one of the ones we advertised.
CBS client_protocol_name_list =
MakeConstSpan(hs->config->alpn_client_proto_list),
client_protocol_name;
while (CBS_len(&client_protocol_name_list) > 0) {
if (!CBS_get_u8_length_prefixed(&client_protocol_name_list,
&client_protocol_name)) {
return false;
}
if (client_protocol_name == protocol) {
return true;
}
}
return false;
}
bool ssl_negotiate_alpn(SSL_HANDSHAKE *hs, uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
CBS contents;
if (ssl->ctx->alpn_select_cb == NULL ||
!ssl_client_hello_get_extension(
client_hello, &contents,
TLSEXT_TYPE_application_layer_protocol_negotiation)) {
if (ssl->quic_method) {
// ALPN is required when QUIC is used.
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_ALPN);
*out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
return false;
}
// Ignore ALPN if not configured or no extension was supplied.
return true;
}
// ALPN takes precedence over NPN.
hs->next_proto_neg_seen = false;
CBS protocol_name_list;
if (!CBS_get_u16_length_prefixed(&contents, &protocol_name_list) ||
CBS_len(&contents) != 0 ||
CBS_len(&protocol_name_list) < 2) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// Validate the protocol list.
CBS protocol_name_list_copy = protocol_name_list;
while (CBS_len(&protocol_name_list_copy) > 0) {
CBS protocol_name;
if (!CBS_get_u8_length_prefixed(&protocol_name_list_copy, &protocol_name) ||
// Empty protocol names are forbidden.
CBS_len(&protocol_name) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
}
const uint8_t *selected;
uint8_t selected_len;
if (ssl->ctx->alpn_select_cb(
ssl, &selected, &selected_len, CBS_data(&protocol_name_list),
CBS_len(&protocol_name_list),
ssl->ctx->alpn_select_cb_arg) == SSL_TLSEXT_ERR_OK) {
if (selected_len == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
if (!ssl->s3->alpn_selected.CopyFrom(
MakeConstSpan(selected, selected_len))) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
} else if (ssl->quic_method) {
// ALPN is required when QUIC is used.
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_ALPN);
*out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
return false;
}
return true;
}
static bool ext_alpn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->s3->alpn_selected.empty()) {
return true;
}
CBB contents, proto_list, proto;
if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &proto_list) ||
!CBB_add_u8_length_prefixed(&proto_list, &proto) ||
!CBB_add_bytes(&proto, ssl->s3->alpn_selected.data(),
ssl->s3->alpn_selected.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Channel ID.
//
// https://tools.ietf.org/html/draft-balfanz-tls-channelid-01
static void ext_channel_id_init(SSL_HANDSHAKE *hs) {
hs->ssl->s3->channel_id_valid = false;
}
static bool ext_channel_id_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!hs->config->channel_id_enabled || SSL_is_dtls(ssl)) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
static bool ext_channel_id_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
assert(!SSL_is_dtls(ssl));
assert(hs->config->channel_id_enabled);
if (CBS_len(contents) != 0) {
return false;
}
ssl->s3->channel_id_valid = true;
return true;
}
static bool ext_channel_id_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL || !hs->config->channel_id_enabled || SSL_is_dtls(ssl)) {
return true;
}
if (CBS_len(contents) != 0) {
return false;
}
ssl->s3->channel_id_valid = true;
return true;
}
static bool ext_channel_id_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!ssl->s3->channel_id_valid) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16(out, 0 /* length */)) {
return false;
}
return true;
}
// Secure Real-time Transport Protocol (SRTP) extension.
//
// https://tools.ietf.org/html/rfc5764
static void ext_srtp_init(SSL_HANDSHAKE *hs) {
hs->ssl->s3->srtp_profile = NULL;
}
static bool ext_srtp_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
STACK_OF(SRTP_PROTECTION_PROFILE) *profiles = SSL_get_srtp_profiles(ssl);
if (profiles == NULL ||
sk_SRTP_PROTECTION_PROFILE_num(profiles) == 0) {
return true;
}
CBB contents, profile_ids;
if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &profile_ids)) {
return false;
}
for (const SRTP_PROTECTION_PROFILE *profile : profiles) {
if (!CBB_add_u16(&profile_ids, profile->id)) {
return false;
}
}
if (!CBB_add_u8(&contents, 0 /* empty use_mki value */) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_srtp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
// The extension consists of a u16-prefixed profile ID list containing a
// single uint16_t profile ID, then followed by a u8-prefixed srtp_mki field.
//
// See https://tools.ietf.org/html/rfc5764#section-4.1.1
CBS profile_ids, srtp_mki;
uint16_t profile_id;
if (!CBS_get_u16_length_prefixed(contents, &profile_ids) ||
!CBS_get_u16(&profile_ids, &profile_id) ||
CBS_len(&profile_ids) != 0 ||
!CBS_get_u8_length_prefixed(contents, &srtp_mki) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
return false;
}
if (CBS_len(&srtp_mki) != 0) {
// Must be no MKI, since we never offer one.
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_MKI_VALUE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
STACK_OF(SRTP_PROTECTION_PROFILE) *profiles = SSL_get_srtp_profiles(ssl);
// Check to see if the server gave us something we support (and presumably
// offered).
for (const SRTP_PROTECTION_PROFILE *profile : profiles) {
if (profile->id == profile_id) {
ssl->s3->srtp_profile = profile;
return true;
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
static bool ext_srtp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return true;
}
CBS profile_ids, srtp_mki;
if (!CBS_get_u16_length_prefixed(contents, &profile_ids) ||
CBS_len(&profile_ids) < 2 ||
!CBS_get_u8_length_prefixed(contents, &srtp_mki) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
return false;
}
// Discard the MKI value for now.
const STACK_OF(SRTP_PROTECTION_PROFILE) *server_profiles =
SSL_get_srtp_profiles(ssl);
// Pick the server's most preferred profile.
for (const SRTP_PROTECTION_PROFILE *server_profile : server_profiles) {
CBS profile_ids_tmp;
CBS_init(&profile_ids_tmp, CBS_data(&profile_ids), CBS_len(&profile_ids));
while (CBS_len(&profile_ids_tmp) > 0) {
uint16_t profile_id;
if (!CBS_get_u16(&profile_ids_tmp, &profile_id)) {
return false;
}
if (server_profile->id == profile_id) {
ssl->s3->srtp_profile = server_profile;
return true;
}
}
}
return true;
}
static bool ext_srtp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->s3->srtp_profile == NULL) {
return true;
}
CBB contents, profile_ids;
if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &profile_ids) ||
!CBB_add_u16(&profile_ids, ssl->s3->srtp_profile->id) ||
!CBB_add_u8(&contents, 0 /* empty MKI */) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// EC point formats.
//
// https://tools.ietf.org/html/rfc4492#section-5.1.2
static bool ext_ec_point_add_extension(SSL_HANDSHAKE *hs, CBB *out) {
CBB contents, formats;
if (!CBB_add_u16(out, TLSEXT_TYPE_ec_point_formats) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &formats) ||
!CBB_add_u8(&formats, TLSEXT_ECPOINTFORMAT_uncompressed) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_ec_point_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
// The point format extension is unnecessary in TLS 1.3.
if (hs->min_version >= TLS1_3_VERSION) {
return true;
}
return ext_ec_point_add_extension(hs, out);
}
static bool ext_ec_point_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return false;
}
CBS ec_point_format_list;
if (!CBS_get_u8_length_prefixed(contents, &ec_point_format_list) ||
CBS_len(contents) != 0) {
return false;
}
// Per RFC 4492, section 5.1.2, implementations MUST support the uncompressed
// point format.
if (OPENSSL_memchr(CBS_data(&ec_point_format_list),
TLSEXT_ECPOINTFORMAT_uncompressed,
CBS_len(&ec_point_format_list)) == NULL) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
return true;
}
static bool ext_ec_point_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return true;
}
return ext_ec_point_parse_serverhello(hs, out_alert, contents);
}
static bool ext_ec_point_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
return true;
}
const uint32_t alg_k = hs->new_cipher->algorithm_mkey;
const uint32_t alg_a = hs->new_cipher->algorithm_auth;
const bool using_ecc = (alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA);
if (!using_ecc) {
return true;
}
return ext_ec_point_add_extension(hs, out);
}
// Pre Shared Key
//
// https://tools.ietf.org/html/rfc8446#section-4.2.11
static size_t ext_pre_shared_key_clienthello_length(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (hs->max_version < TLS1_3_VERSION || ssl->session == nullptr ||
ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) {
return 0;
}
size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get()));
return 15 + ssl->session->ticket.size() + binder_len;
}
static bool ext_pre_shared_key_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
hs->needs_psk_binder = false;
if (hs->max_version < TLS1_3_VERSION || ssl->session == nullptr ||
ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) {
return true;
}
// Per RFC 8446 section 4.1.4, skip offering the session if the selected
// cipher in HelloRetryRequest does not match. This avoids performing the
// transcript hash transformation for multiple hashes.
if (ssl->s3 && ssl->s3->used_hello_retry_request &&
ssl->session->cipher->algorithm_prf != hs->new_cipher->algorithm_prf) {
return true;
}
struct OPENSSL_timeval now;
ssl_get_current_time(ssl, &now);
uint32_t ticket_age = 1000 * (now.tv_sec - ssl->session->time);
uint32_t obfuscated_ticket_age = ticket_age + ssl->session->ticket_age_add;
// Fill in a placeholder zero binder of the appropriate length. It will be
// computed and filled in later after length prefixes are computed.
uint8_t zero_binder[EVP_MAX_MD_SIZE] = {0};
size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get()));
CBB contents, identity, ticket, binders, binder;
if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &identity) ||
!CBB_add_u16_length_prefixed(&identity, &ticket) ||
!CBB_add_bytes(&ticket, ssl->session->ticket.data(),
ssl->session->ticket.size()) ||
!CBB_add_u32(&identity, obfuscated_ticket_age) ||
!CBB_add_u16_length_prefixed(&contents, &binders) ||
!CBB_add_u8_length_prefixed(&binders, &binder) ||
!CBB_add_bytes(&binder, zero_binder, binder_len)) {
return false;
}
hs->needs_psk_binder = true;
return CBB_flush(out);
}
bool ssl_ext_pre_shared_key_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
uint16_t psk_id;
if (!CBS_get_u16(contents, &psk_id) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// We only advertise one PSK identity, so the only legal index is zero.
if (psk_id != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND);
*out_alert = SSL_AD_UNKNOWN_PSK_IDENTITY;
return false;
}
return true;
}
bool ssl_ext_pre_shared_key_parse_clienthello(
SSL_HANDSHAKE *hs, CBS *out_ticket, CBS *out_binders,
uint32_t *out_obfuscated_ticket_age, uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello, CBS *contents) {
// Verify that the pre_shared_key extension is the last extension in
// ClientHello.
if (CBS_data(contents) + CBS_len(contents) !=
client_hello->extensions + client_hello->extensions_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PRE_SHARED_KEY_MUST_BE_LAST);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// We only process the first PSK identity since we don't support pure PSK.
CBS identities, binders;
if (!CBS_get_u16_length_prefixed(contents, &identities) ||
!CBS_get_u16_length_prefixed(&identities, out_ticket) ||
!CBS_get_u32(&identities, out_obfuscated_ticket_age) ||
!CBS_get_u16_length_prefixed(contents, &binders) ||
CBS_len(&binders) == 0 ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
*out_binders = binders;
// Check the syntax of the remaining identities, but do not process them.
size_t num_identities = 1;
while (CBS_len(&identities) != 0) {
CBS unused_ticket;
uint32_t unused_obfuscated_ticket_age;
if (!CBS_get_u16_length_prefixed(&identities, &unused_ticket) ||
!CBS_get_u32(&identities, &unused_obfuscated_ticket_age)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
num_identities++;
}
// Check the syntax of the binders. The value will be checked later if
// resuming.
size_t num_binders = 0;
while (CBS_len(&binders) != 0) {
CBS binder;
if (!CBS_get_u8_length_prefixed(&binders, &binder)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
num_binders++;
}
if (num_identities != num_binders) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_BINDER_COUNT_MISMATCH);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
return true;
}
bool ssl_ext_pre_shared_key_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ssl->s3->session_reused) {
return true;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
// We only consider the first identity for resumption
!CBB_add_u16(&contents, 0) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Pre-Shared Key Exchange Modes
//
// https://tools.ietf.org/html/rfc8446#section-4.2.9
static bool ext_psk_key_exchange_modes_add_clienthello(SSL_HANDSHAKE *hs,
CBB *out) {
if (hs->max_version < TLS1_3_VERSION) {
return true;
}
CBB contents, ke_modes;
if (!CBB_add_u16(out, TLSEXT_TYPE_psk_key_exchange_modes) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &ke_modes) ||
!CBB_add_u8(&ke_modes, SSL_PSK_DHE_KE)) {
return false;
}
return CBB_flush(out);
}
static bool ext_psk_key_exchange_modes_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
CBS ke_modes;
if (!CBS_get_u8_length_prefixed(contents, &ke_modes) ||
CBS_len(&ke_modes) == 0 ||
CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// We only support tickets with PSK_DHE_KE.
hs->accept_psk_mode = OPENSSL_memchr(CBS_data(&ke_modes), SSL_PSK_DHE_KE,
CBS_len(&ke_modes)) != NULL;
return true;
}
// Early Data Indication
//
// https://tools.ietf.org/html/rfc8446#section-4.2.10
// ssl_get_local_application_settings looks up the configured ALPS value for
// |protocol|. If found, it sets |*out_settings| to the value and returns true.
// Otherwise, it returns false.
static bool ssl_get_local_application_settings(
const SSL_HANDSHAKE *hs, Span<const uint8_t> *out_settings,
Span<const uint8_t> protocol) {
for (const ALPSConfig &config : hs->config->alps_configs) {
if (protocol == config.protocol) {
*out_settings = config.settings;
return true;
}
}
return false;
}
static bool ext_early_data_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// The second ClientHello never offers early data, and we must have already
// filled in |early_data_reason| by this point.
if (ssl->s3->used_hello_retry_request) {
assert(ssl->s3->early_data_reason != ssl_early_data_unknown);
return true;
}
if (!ssl->enable_early_data) {
ssl->s3->early_data_reason = ssl_early_data_disabled;
return true;
}
if (hs->max_version < TLS1_3_VERSION) {
// We discard inapplicable sessions, so this is redundant with the session
// checks below, but we check give a more useful reason.
ssl->s3->early_data_reason = ssl_early_data_protocol_version;
return true;
}
if (ssl->session == nullptr) {
ssl->s3->early_data_reason = ssl_early_data_no_session_offered;
return true;
}
if (ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION ||
ssl->session->ticket_max_early_data == 0) {
ssl->s3->early_data_reason = ssl_early_data_unsupported_for_session;
return true;
}
if (!ssl->session->early_alpn.empty()) {
if (!ssl_is_alpn_protocol_allowed(hs, ssl->session->early_alpn)) {
// Avoid reporting a confusing value in |SSL_get0_alpn_selected|.
ssl->s3->early_data_reason = ssl_early_data_alpn_mismatch;
return true;
}
Span<const uint8_t> settings;
bool has_alps = ssl_get_local_application_settings(
hs, &settings, ssl->session->early_alpn);
if (has_alps != ssl->session->has_application_settings ||
settings != ssl->session->local_application_settings) {
// 0-RTT carries ALPS over, so we only offer it when the value matches.
ssl->s3->early_data_reason = ssl_early_data_alps_mismatch;
return true;
}
}
// |early_data_reason| will be filled in later when the server responds.
hs->early_data_offered = true;
if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) ||
!CBB_add_u16(out, 0) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_early_data_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
if (hs->early_data_offered && !ssl->s3->used_hello_retry_request) {
ssl->s3->early_data_reason = ssl->s3->session_reused
? ssl_early_data_peer_declined
: ssl_early_data_session_not_resumed;
} else {
// We already filled in |early_data_reason| when declining to offer 0-RTT
// or handling the implicit HelloRetryRequest reject.
assert(ssl->s3->early_data_reason != ssl_early_data_unknown);
}
return true;
}
// If we received an HRR, the second ClientHello never offers early data, so
// the extensions logic will automatically reject early data extensions as
// unsolicited. This covered by the ServerAcceptsEarlyDataOnHRR test.
assert(!ssl->s3->used_hello_retry_request);
if (CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
if (!ssl->s3->session_reused) {
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
return false;
}
ssl->s3->early_data_reason = ssl_early_data_accepted;
ssl->s3->early_data_accepted = true;
return true;
}
static bool ext_early_data_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert, CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL ||
ssl_protocol_version(ssl) < TLS1_3_VERSION) {
return true;
}
if (CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
hs->early_data_offered = true;
return true;
}
static bool ext_early_data_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ssl->s3->early_data_accepted) {
return true;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) ||
!CBB_add_u16(out, 0) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Key Share
//
// https://tools.ietf.org/html/rfc8446#section-4.2.8
static bool ext_key_share_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (hs->max_version < TLS1_3_VERSION) {
return true;
}
CBB contents, kse_bytes;
if (!CBB_add_u16(out, TLSEXT_TYPE_key_share) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &kse_bytes)) {
return false;
}
uint16_t group_id = hs->retry_group;
uint16_t second_group_id = 0;
if (ssl->s3 && ssl->s3->used_hello_retry_request) {
// We received a HelloRetryRequest without a new curve, so there is no new
// share to append. Leave |hs->key_share| as-is.
if (group_id == 0 &&
!CBB_add_bytes(&kse_bytes, hs->key_share_bytes.data(),
hs->key_share_bytes.size())) {
return false;
}
hs->key_share_bytes.Reset();
if (group_id == 0) {
return CBB_flush(out);
}
} else {
// Add a fake group. See draft-davidben-tls-grease-01.
if (ssl->ctx->grease_enabled &&
(!CBB_add_u16(&kse_bytes,
ssl_get_grease_value(hs, ssl_grease_group)) ||
!CBB_add_u16(&kse_bytes, 1 /* length */) ||
!CBB_add_u8(&kse_bytes, 0 /* one byte key share */))) {
return false;
}
// Predict the most preferred group.
Span<const uint16_t> groups = tls1_get_grouplist(hs);
if (groups.empty()) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_GROUPS_SPECIFIED);
return false;
}
group_id = groups[0];
if (is_post_quantum_group(group_id) && groups.size() >= 2) {
// CECPQ2(b) is not sent as the only initial key share. We'll include the
// 2nd preference group too to avoid round-trips.
second_group_id = groups[1];
assert(second_group_id != group_id);
}
}
CBB key_exchange;
hs->key_shares[0] = SSLKeyShare::Create(group_id);
if (!hs->key_shares[0] ||
!CBB_add_u16(&kse_bytes, group_id) ||
!CBB_add_u16_length_prefixed(&kse_bytes, &key_exchange) ||
!hs->key_shares[0]->Offer(&key_exchange) ||
!CBB_flush(&kse_bytes)) {
return false;
}
if (second_group_id != 0) {
hs->key_shares[1] = SSLKeyShare::Create(second_group_id);
if (!hs->key_shares[1] ||
!CBB_add_u16(&kse_bytes, second_group_id) ||
!CBB_add_u16_length_prefixed(&kse_bytes, &key_exchange) ||
!hs->key_shares[1]->Offer(&key_exchange) ||
!CBB_flush(&kse_bytes)) {
return false;
}
}
// Save the contents of the extension to repeat it in the second
// ClientHello.
if (ssl->s3 && !ssl->s3->used_hello_retry_request &&
!hs->key_share_bytes.CopyFrom(
MakeConstSpan(CBB_data(&kse_bytes), CBB_len(&kse_bytes)))) {
return false;
}
return CBB_flush(out);
}
bool ssl_ext_key_share_parse_serverhello(SSL_HANDSHAKE *hs,
Array<uint8_t> *out_secret,
uint8_t *out_alert, CBS *contents) {
CBS peer_key;
uint16_t group_id;
if (!CBS_get_u16(contents, &group_id) ||
!CBS_get_u16_length_prefixed(contents, &peer_key) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
SSLKeyShare *key_share = hs->key_shares[0].get();
if (key_share->GroupID() != group_id) {
if (!hs->key_shares[1] || hs->key_shares[1]->GroupID() != group_id) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
return false;
}
key_share = hs->key_shares[1].get();
}
if (!key_share->Finish(out_secret, out_alert, peer_key)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
hs->new_session->group_id = group_id;
hs->key_shares[0].reset();
hs->key_shares[1].reset();
return true;
}
bool ssl_ext_key_share_parse_clienthello(SSL_HANDSHAKE *hs, bool *out_found,
Array<uint8_t> *out_secret,
uint8_t *out_alert, CBS *contents) {
uint16_t group_id;
CBS key_shares;
if (!tls1_get_shared_group(hs, &group_id)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_GROUP);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return false;
}
if (!CBS_get_u16_length_prefixed(contents, &key_shares) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return false;
}
// Find the corresponding key share.
CBS peer_key;
CBS_init(&peer_key, NULL, 0);
while (CBS_len(&key_shares) > 0) {
uint16_t id;
CBS peer_key_tmp;
if (!CBS_get_u16(&key_shares, &id) ||
!CBS_get_u16_length_prefixed(&key_shares, &peer_key_tmp) ||
CBS_len(&peer_key_tmp) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return false;
}
if (id == group_id) {
if (CBS_len(&peer_key) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_KEY_SHARE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
peer_key = peer_key_tmp;
// Continue parsing the structure to keep peers honest.
}
}
if (CBS_len(&peer_key) == 0) {
*out_found = false;
out_secret->Reset();
return true;
}
// Compute the DH secret.
Array<uint8_t> secret;
ScopedCBB public_key;
UniquePtr<SSLKeyShare> key_share = SSLKeyShare::Create(group_id);
if (!key_share ||
!CBB_init(public_key.get(), 32) ||
!key_share->Accept(public_key.get(), &secret, out_alert, peer_key) ||
!CBBFinishArray(public_key.get(), &hs->ecdh_public_key)) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
*out_secret = std::move(secret);
*out_found = true;
return true;
}
bool ssl_ext_key_share_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
uint16_t group_id;
CBB kse_bytes, public_key;
if (!tls1_get_shared_group(hs, &group_id) ||
!CBB_add_u16(out, TLSEXT_TYPE_key_share) ||
!CBB_add_u16_length_prefixed(out, &kse_bytes) ||
!CBB_add_u16(&kse_bytes, group_id) ||
!CBB_add_u16_length_prefixed(&kse_bytes, &public_key) ||
!CBB_add_bytes(&public_key, hs->ecdh_public_key.data(),
hs->ecdh_public_key.size()) ||
!CBB_flush(out)) {
return false;
}
hs->ecdh_public_key.Reset();
hs->new_session->group_id = group_id;
return true;
}
// Supported Versions
//
// https://tools.ietf.org/html/rfc8446#section-4.2.1
static bool ext_supported_versions_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (hs->max_version <= TLS1_2_VERSION) {
return true;
}
CBB contents, versions;
if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &versions)) {
return false;
}
// Add a fake version. See draft-davidben-tls-grease-01.
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&versions, ssl_get_grease_value(hs, ssl_grease_version))) {
return false;
}
if (!ssl_add_supported_versions(hs, &versions) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Cookie
//
// https://tools.ietf.org/html/rfc8446#section-4.2.2
static bool ext_cookie_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->cookie.empty()) {
return true;
}
CBB contents, cookie;
if (!CBB_add_u16(out, TLSEXT_TYPE_cookie) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &cookie) ||
!CBB_add_bytes(&cookie, hs->cookie.data(), hs->cookie.size()) ||
!CBB_flush(out)) {
return false;
}
// The cookie is no longer needed in memory.
hs->cookie.Reset();
return true;
}
// Supported Groups
//
// https://tools.ietf.org/html/rfc4492#section-5.1.1
// https://tools.ietf.org/html/rfc8446#section-4.2.7
static bool ext_supported_groups_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
CBB contents, groups_bytes;
if (!CBB_add_u16(out, TLSEXT_TYPE_supported_groups) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &groups_bytes)) {
return false;
}
// Add a fake group. See draft-davidben-tls-grease-01.
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&groups_bytes,
ssl_get_grease_value(hs, ssl_grease_group))) {
return false;
}
for (uint16_t group : tls1_get_grouplist(hs)) {
if (is_post_quantum_group(group) &&
hs->max_version < TLS1_3_VERSION) {
continue;
}
if (!CBB_add_u16(&groups_bytes, group)) {
return false;
}
}
return CBB_flush(out);
}
static bool ext_supported_groups_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
// This extension is not expected to be echoed by servers in TLS 1.2, but some
// BigIP servers send it nonetheless, so do not enforce this.
return true;
}
static bool parse_u16_array(const CBS *cbs, Array<uint16_t> *out) {
CBS copy = *cbs;
if ((CBS_len(&copy) & 1) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return false;
}
Array<uint16_t> ret;
if (!ret.Init(CBS_len(&copy) / 2)) {
return false;
}
for (size_t i = 0; i < ret.size(); i++) {
if (!CBS_get_u16(&copy, &ret[i])) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
}
assert(CBS_len(&copy) == 0);
*out = std::move(ret);
return 1;
}
static bool ext_supported_groups_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return true;
}
CBS supported_group_list;
if (!CBS_get_u16_length_prefixed(contents, &supported_group_list) ||
CBS_len(&supported_group_list) == 0 ||
CBS_len(contents) != 0 ||
!parse_u16_array(&supported_group_list, &hs->peer_supported_group_list)) {
return false;
}
return true;
}
// Token Binding
//
// https://tools.ietf.org/html/draft-ietf-tokbind-negotiation-10
// The Token Binding version number currently matches the draft number of
// draft-ietf-tokbind-protocol, and when published as an RFC it will be 0x0100.
// Since there are no wire changes to the protocol from draft 13 through the
// current draft (16), this implementation supports all versions in that range.
static uint16_t kTokenBindingMaxVersion = 16;
static uint16_t kTokenBindingMinVersion = 13;
static bool ext_token_binding_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (hs->config->token_binding_params.empty() || SSL_is_dtls(ssl)) {
return true;
}
CBB contents, params;
if (!CBB_add_u16(out, TLSEXT_TYPE_token_binding) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16(&contents, kTokenBindingMaxVersion) ||
!CBB_add_u8_length_prefixed(&contents, &params) ||
!CBB_add_bytes(&params, hs->config->token_binding_params.data(),
hs->config->token_binding_params.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_token_binding_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == nullptr) {
return true;
}
CBS params_list;
uint16_t version;
uint8_t param;
if (!CBS_get_u16(contents, &version) ||
!CBS_get_u8_length_prefixed(contents, &params_list) ||
!CBS_get_u8(&params_list, &param) ||
CBS_len(&params_list) > 0 ||
CBS_len(contents) > 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// The server-negotiated version must be less than or equal to our version.
if (version > kTokenBindingMaxVersion) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// If the server-selected version is less than what we support, then Token
// Binding wasn't negotiated (but the extension was parsed successfully).
if (version < kTokenBindingMinVersion) {
return true;
}
for (uint8_t config_param : hs->config->token_binding_params) {
if (param == config_param) {
ssl->s3->negotiated_token_binding_param = param;
ssl->s3->token_binding_negotiated = true;
return true;
}
}
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return false;
}
// select_tb_param looks for the first token binding param in
// |hs->ssl->token_binding_params| that is also in |params| and puts it in
// |hs->ssl->negotiated_token_binding_param|. It returns true if a token binding
// param is found, and false otherwise.
static bool select_tb_param(SSL_HANDSHAKE *hs,
Span<const uint8_t> peer_params) {
for (uint8_t tb_param : hs->config->token_binding_params) {
for (uint8_t peer_param : peer_params) {
if (tb_param == peer_param) {
hs->ssl->s3->negotiated_token_binding_param = tb_param;
return true;
}
}
}
return false;
}
static bool ext_token_binding_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == nullptr || hs->config->token_binding_params.empty()) {
return true;
}
CBS params;
uint16_t version;
if (!CBS_get_u16(contents, &version) ||
!CBS_get_u8_length_prefixed(contents, &params) ||
CBS_len(&params) == 0 ||
CBS_len(contents) > 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// If the client-selected version is less than what we support, then Token
// Binding wasn't negotiated (but the extension was parsed successfully).
if (version < kTokenBindingMinVersion) {
return true;
}
// If the client-selected version is higher than we support, use our max
// version. Otherwise, use the client's version.
hs->negotiated_token_binding_version =
std::min(version, kTokenBindingMaxVersion);
if (!select_tb_param(hs, params)) {
return true;
}
ssl->s3->token_binding_negotiated = true;
return true;
}
static bool ext_token_binding_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!ssl->s3->token_binding_negotiated) {
return true;
}
CBB contents, params;
if (!CBB_add_u16(out, TLSEXT_TYPE_token_binding) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16(&contents, hs->negotiated_token_binding_version) ||
!CBB_add_u8_length_prefixed(&contents, &params) ||
!CBB_add_u8(&params, ssl->s3->negotiated_token_binding_param) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// QUIC Transport Parameters
static bool ext_quic_transport_params_add_clienthello(SSL_HANDSHAKE *hs,
CBB *out) {
if (hs->config->quic_transport_params.empty() && !hs->ssl->quic_method) {
return true;
}
if (hs->config->quic_transport_params.empty() || !hs->ssl->quic_method) {
// QUIC Transport Parameters must be sent over QUIC, and they must not be
// sent over non-QUIC transports. If transport params are set, then
// SSL(_CTX)_set_quic_method must also be called.
OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
return false;
}
assert(hs->min_version > TLS1_2_VERSION);
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_quic_transport_parameters) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents, hs->config->quic_transport_params.data(),
hs->config->quic_transport_params.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
static bool ext_quic_transport_params_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == nullptr) {
if (!ssl->quic_method) {
return true;
}
assert(ssl->quic_method);
*out_alert = SSL_AD_MISSING_EXTENSION;
return false;
}
if (!ssl->quic_method) {
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return false;
}
// QUIC requires TLS 1.3.
assert(ssl_protocol_version(ssl) == TLS1_3_VERSION);
return ssl->s3->peer_quic_transport_params.CopyFrom(*contents);
}
static bool ext_quic_transport_params_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (!contents) {
if (!ssl->quic_method) {
if (hs->config->quic_transport_params.empty()) {
return true;
}
// QUIC transport parameters must not be set if |ssl| is not configured
// for QUIC.
OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
*out_alert = SSL_AD_INTERNAL_ERROR;
}
*out_alert = SSL_AD_MISSING_EXTENSION;
return false;
}
if (!ssl->quic_method) {
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return false;
}
assert(ssl_protocol_version(ssl) == TLS1_3_VERSION);
return ssl->s3->peer_quic_transport_params.CopyFrom(*contents);
}
static bool ext_quic_transport_params_add_serverhello(SSL_HANDSHAKE *hs,
CBB *out) {
assert(hs->ssl->quic_method != nullptr);
if (hs->config->quic_transport_params.empty()) {
// Transport parameters must be set when using QUIC.
OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
return false;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_quic_transport_parameters) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents, hs->config->quic_transport_params.data(),
hs->config->quic_transport_params.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
// Delegated credentials.
//
// https://tools.ietf.org/html/draft-ietf-tls-subcerts
static bool ext_delegated_credential_add_clienthello(SSL_HANDSHAKE *hs,
CBB *out) {
return true;
}
static bool ext_delegated_credential_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr || ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
// Don't use delegated credentials unless we're negotiating TLS 1.3 or
// higher.
return true;
}
// The contents of the extension are the signature algorithms the client will
// accept for a delegated credential.
CBS sigalg_list;
if (!CBS_get_u16_length_prefixed(contents, &sigalg_list) ||
CBS_len(&sigalg_list) == 0 ||
CBS_len(contents) != 0 ||
!parse_u16_array(&sigalg_list, &hs->peer_delegated_credential_sigalgs)) {
return false;
}
hs->delegated_credential_requested = true;
return true;
}
// Certificate compression
static bool cert_compression_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
bool first = true;
CBB contents, algs;
for (const auto &alg : hs->ssl->ctx->cert_compression_algs) {
if (alg.decompress == nullptr) {
continue;
}
if (first && (!CBB_add_u16(out, TLSEXT_TYPE_cert_compression) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u8_length_prefixed(&contents, &algs))) {
return false;
}
first = false;
if (!CBB_add_u16(&algs, alg.alg_id)) {
return false;
}
}
return first || CBB_flush(out);
}
static bool cert_compression_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr) {
return true;
}
// The server may not echo this extension. Any server to client negotiation is
// advertised in the CertificateRequest message.
return false;
}
static bool cert_compression_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == nullptr) {
return true;
}
const SSL_CTX *ctx = hs->ssl->ctx.get();
const size_t num_algs = ctx->cert_compression_algs.size();
CBS alg_ids;
if (!CBS_get_u8_length_prefixed(contents, &alg_ids) ||
CBS_len(contents) != 0 ||
CBS_len(&alg_ids) == 0 ||
CBS_len(&alg_ids) % 2 == 1) {
return false;
}
const size_t num_given_alg_ids = CBS_len(&alg_ids) / 2;
Array<uint16_t> given_alg_ids;
if (!given_alg_ids.Init(num_given_alg_ids)) {
return false;
}
size_t best_index = num_algs;
size_t given_alg_idx = 0;
while (CBS_len(&alg_ids) > 0) {
uint16_t alg_id;
if (!CBS_get_u16(&alg_ids, &alg_id)) {
return false;
}
given_alg_ids[given_alg_idx++] = alg_id;
for (size_t i = 0; i < num_algs; i++) {
const auto &alg = ctx->cert_compression_algs[i];
if (alg.alg_id == alg_id && alg.compress != nullptr) {
if (i < best_index) {
best_index = i;
}
break;
}
}
}
qsort(given_alg_ids.data(), given_alg_ids.size(), sizeof(uint16_t),
compare_uint16_t);
for (size_t i = 1; i < num_given_alg_ids; i++) {
if (given_alg_ids[i - 1] == given_alg_ids[i]) {
return false;
}
}
if (best_index < num_algs &&
ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
hs->cert_compression_negotiated = true;
hs->cert_compression_alg_id = ctx->cert_compression_algs[best_index].alg_id;
}
return true;
}
static bool cert_compression_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
return true;
}
// Application-level Protocol Settings
//
// https://tools.ietf.org/html/draft-vvv-tls-alps-01
static bool ext_alps_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (// ALPS requires TLS 1.3.
hs->max_version < TLS1_3_VERSION ||
// Do not offer ALPS without ALPN.
hs->config->alpn_client_proto_list.empty() ||
// Do not offer ALPS if not configured.
hs->config->alps_configs.empty() ||
// Do not offer ALPS on renegotiation handshakes.
ssl->s3->initial_handshake_complete) {
return true;
}
CBB contents, proto_list, proto;
if (!CBB_add_u16(out, TLSEXT_TYPE_application_settings) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_u16_length_prefixed(&contents, &proto_list)) {
return false;
}
for (const ALPSConfig &config : hs->config->alps_configs) {
if (!CBB_add_u8_length_prefixed(&proto_list, &proto) ||
!CBB_add_bytes(&proto, config.protocol.data(),
config.protocol.size())) {
return false;
}
}
return CBB_flush(out);
}
static bool ext_alps_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == nullptr) {
return true;
}
assert(!ssl->s3->initial_handshake_complete);
assert(!hs->config->alpn_client_proto_list.empty());
assert(!hs->config->alps_configs.empty());
// ALPS requires TLS 1.3.
if (ssl_protocol_version(ssl) < TLS1_3_VERSION) {
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
return false;
}
// Note extension callbacks may run in any order, so we defer checking
// consistency with ALPN to |ssl_check_serverhello_tlsext|.
if (!hs->new_session->peer_application_settings.CopyFrom(*contents)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
hs->new_session->has_application_settings = true;
return true;
}
static bool ext_alps_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
// If early data is accepted, we omit the ALPS extension. It is implicitly
// carried over from the previous connection.
if (hs->new_session == nullptr ||
!hs->new_session->has_application_settings ||
ssl->s3->early_data_accepted) {
return true;
}
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_application_settings) ||
!CBB_add_u16_length_prefixed(out, &contents) ||
!CBB_add_bytes(&contents,
hs->new_session->local_application_settings.data(),
hs->new_session->local_application_settings.size()) ||
!CBB_flush(out)) {
return false;
}
return true;
}
bool ssl_negotiate_alps(SSL_HANDSHAKE *hs, uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
if (ssl->s3->alpn_selected.empty()) {
return true;
}
// If we negotiate ALPN over TLS 1.3, try to negotiate ALPS.
CBS alps_contents;
Span<const uint8_t> settings;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION &&
ssl_get_local_application_settings(hs, &settings,
ssl->s3->alpn_selected) &&
ssl_client_hello_get_extension(client_hello, &alps_contents,
TLSEXT_TYPE_application_settings)) {
// Check if the client supports ALPS with the selected ALPN.
bool found = false;
CBS alps_list;
if (!CBS_get_u16_length_prefixed(&alps_contents, &alps_list) ||
CBS_len(&alps_contents) != 0 ||
CBS_len(&alps_list) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
while (CBS_len(&alps_list) > 0) {
CBS protocol_name;
if (!CBS_get_u8_length_prefixed(&alps_list, &protocol_name) ||
// Empty protocol names are forbidden.
CBS_len(&protocol_name) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
if (protocol_name == MakeConstSpan(ssl->s3->alpn_selected)) {
found = true;
}
}
// Negotiate ALPS if both client also supports ALPS for this protocol.
if (found) {
hs->new_session->has_application_settings = true;
if (!hs->new_session->local_application_settings.CopyFrom(settings)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
}
}
return true;
}
// kExtensions contains all the supported extensions.
static const struct tls_extension kExtensions[] = {
{
TLSEXT_TYPE_server_name,
NULL,
ext_sni_add_clienthello,
ext_sni_parse_serverhello,
ext_sni_parse_clienthello,
ext_sni_add_serverhello,
},
{
TLSEXT_TYPE_encrypted_client_hello,
NULL,
ext_ech_add_clienthello,
ext_ech_parse_serverhello,
ignore_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_extended_master_secret,
NULL,
ext_ems_add_clienthello,
ext_ems_parse_serverhello,
ext_ems_parse_clienthello,
ext_ems_add_serverhello,
},
{
TLSEXT_TYPE_renegotiate,
NULL,
ext_ri_add_clienthello,
ext_ri_parse_serverhello,
ext_ri_parse_clienthello,
ext_ri_add_serverhello,
},
{
TLSEXT_TYPE_supported_groups,
NULL,
ext_supported_groups_add_clienthello,
ext_supported_groups_parse_serverhello,
ext_supported_groups_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_ec_point_formats,
NULL,
ext_ec_point_add_clienthello,
ext_ec_point_parse_serverhello,
ext_ec_point_parse_clienthello,
ext_ec_point_add_serverhello,
},
{
TLSEXT_TYPE_session_ticket,
NULL,
ext_ticket_add_clienthello,
ext_ticket_parse_serverhello,
// Ticket extension client parsing is handled in ssl_session.c
ignore_parse_clienthello,
ext_ticket_add_serverhello,
},
{
TLSEXT_TYPE_application_layer_protocol_negotiation,
NULL,
ext_alpn_add_clienthello,
ext_alpn_parse_serverhello,
// ALPN is negotiated late in |ssl_negotiate_alpn|.
ignore_parse_clienthello,
ext_alpn_add_serverhello,
},
{
TLSEXT_TYPE_status_request,
NULL,
ext_ocsp_add_clienthello,
ext_ocsp_parse_serverhello,
ext_ocsp_parse_clienthello,
ext_ocsp_add_serverhello,
},
{
TLSEXT_TYPE_signature_algorithms,
NULL,
ext_sigalgs_add_clienthello,
forbid_parse_serverhello,
ext_sigalgs_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_next_proto_neg,
NULL,
ext_npn_add_clienthello,
ext_npn_parse_serverhello,
ext_npn_parse_clienthello,
ext_npn_add_serverhello,
},
{
TLSEXT_TYPE_certificate_timestamp,
NULL,
ext_sct_add_clienthello,
ext_sct_parse_serverhello,
ext_sct_parse_clienthello,
ext_sct_add_serverhello,
},
{
TLSEXT_TYPE_channel_id,
ext_channel_id_init,
ext_channel_id_add_clienthello,
ext_channel_id_parse_serverhello,
ext_channel_id_parse_clienthello,
ext_channel_id_add_serverhello,
},
{
TLSEXT_TYPE_srtp,
ext_srtp_init,
ext_srtp_add_clienthello,
ext_srtp_parse_serverhello,
ext_srtp_parse_clienthello,
ext_srtp_add_serverhello,
},
{
TLSEXT_TYPE_key_share,
NULL,
ext_key_share_add_clienthello,
forbid_parse_serverhello,
ignore_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_psk_key_exchange_modes,
NULL,
ext_psk_key_exchange_modes_add_clienthello,
forbid_parse_serverhello,
ext_psk_key_exchange_modes_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_early_data,
NULL,
ext_early_data_add_clienthello,
ext_early_data_parse_serverhello,
ext_early_data_parse_clienthello,
ext_early_data_add_serverhello,
},
{
TLSEXT_TYPE_supported_versions,
NULL,
ext_supported_versions_add_clienthello,
forbid_parse_serverhello,
ignore_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_cookie,
NULL,
ext_cookie_add_clienthello,
forbid_parse_serverhello,
ignore_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_quic_transport_parameters,
NULL,
ext_quic_transport_params_add_clienthello,
ext_quic_transport_params_parse_serverhello,
ext_quic_transport_params_parse_clienthello,
ext_quic_transport_params_add_serverhello,
},
{
TLSEXT_TYPE_token_binding,
NULL,
ext_token_binding_add_clienthello,
ext_token_binding_parse_serverhello,
ext_token_binding_parse_clienthello,
ext_token_binding_add_serverhello,
},
{
TLSEXT_TYPE_cert_compression,
NULL,
cert_compression_add_clienthello,
cert_compression_parse_serverhello,
cert_compression_parse_clienthello,
cert_compression_add_serverhello,
},
{
TLSEXT_TYPE_delegated_credential,
NULL,
ext_delegated_credential_add_clienthello,
forbid_parse_serverhello,
ext_delegated_credential_parse_clienthello,
dont_add_serverhello,
},
{
TLSEXT_TYPE_application_settings,
NULL,
ext_alps_add_clienthello,
ext_alps_parse_serverhello,
// ALPS is negotiated late in |ssl_negotiate_alpn|.
ignore_parse_clienthello,
ext_alps_add_serverhello,
},
};
#define kNumExtensions (sizeof(kExtensions) / sizeof(struct tls_extension))
static_assert(kNumExtensions <=
sizeof(((SSL_HANDSHAKE *)NULL)->extensions.sent) * 8,
"too many extensions for sent bitset");
static_assert(kNumExtensions <=
sizeof(((SSL_HANDSHAKE *)NULL)->extensions.received) * 8,
"too many extensions for received bitset");
static const struct tls_extension *tls_extension_find(uint32_t *out_index,
uint16_t value) {
unsigned i;
for (i = 0; i < kNumExtensions; i++) {
if (kExtensions[i].value == value) {
*out_index = i;
return &kExtensions[i];
}
}
return NULL;
}
bool ssl_add_clienthello_tlsext(SSL_HANDSHAKE *hs, CBB *out,
size_t header_len) {
SSL *const ssl = hs->ssl;
CBB extensions;
if (!CBB_add_u16_length_prefixed(out, &extensions)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
// Note we may send multiple ClientHellos for DTLS HelloVerifyRequest and TLS
// 1.3 HelloRetryRequest. For the latter, the extensions may change, so it is
// important to reset this value.
hs->extensions.sent = 0;
for (size_t i = 0; i < kNumExtensions; i++) {
if (kExtensions[i].init != NULL) {
kExtensions[i].init(hs);
}
}
uint16_t grease_ext1 = 0;
if (ssl->ctx->grease_enabled) {
// Add a fake empty extension. See draft-davidben-tls-grease-01.
grease_ext1 = ssl_get_grease_value(hs, ssl_grease_extension1);
if (!CBB_add_u16(&extensions, grease_ext1) ||
!CBB_add_u16(&extensions, 0 /* zero length */)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
}
bool last_was_empty = false;
for (size_t i = 0; i < kNumExtensions; i++) {
const size_t len_before = CBB_len(&extensions);
if (!kExtensions[i].add_clienthello(hs, &extensions)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
return false;
}
const size_t bytes_written = CBB_len(&extensions) - len_before;
if (bytes_written != 0) {
hs->extensions.sent |= (1u << i);
}
// If the difference in lengths is only four bytes then the extension had
// an empty body.
last_was_empty = (bytes_written == 4);
}
if (ssl->ctx->grease_enabled) {
// Add a fake non-empty extension. See draft-davidben-tls-grease-01.
uint16_t grease_ext2 = ssl_get_grease_value(hs, ssl_grease_extension2);
// The two fake extensions must not have the same value. GREASE values are
// of the form 0x1a1a, 0x2a2a, 0x3a3a, etc., so XOR to generate a different
// one.
if (grease_ext1 == grease_ext2) {
grease_ext2 ^= 0x1010;
}
if (!CBB_add_u16(&extensions, grease_ext2) ||
!CBB_add_u16(&extensions, 1 /* one byte length */) ||
!CBB_add_u8(&extensions, 0 /* single zero byte as contents */)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
last_was_empty = false;
}
if (!SSL_is_dtls(ssl) && !ssl->quic_method) {
size_t psk_extension_len = ext_pre_shared_key_clienthello_length(hs);
header_len += 2 + CBB_len(&extensions) + psk_extension_len;
size_t padding_len = 0;
// The final extension must be non-empty. WebSphere Application
// Server 7.0 is intolerant to the last extension being zero-length. See
// https://crbug.com/363583.
if (last_was_empty && psk_extension_len == 0) {
padding_len = 1;
// The addition of the padding extension may push us into the F5 bug.
header_len += 4 + padding_len;
}
// Add padding to workaround bugs in F5 terminators. See RFC 7685.
//
// NB: because this code works out the length of all existing extensions
// it MUST always appear last (save for any PSK extension).
if (header_len > 0xff && header_len < 0x200) {
// If our calculations already included a padding extension, remove that
// factor because we're about to change its length.
if (padding_len != 0) {
header_len -= 4 + padding_len;
}
padding_len = 0x200 - header_len;
// Extensions take at least four bytes to encode. Always include at least
// one byte of data if including the extension. WebSphere Application
// Server 7.0 is intolerant to the last extension being zero-length. See
// https://crbug.com/363583.
if (padding_len >= 4 + 1) {
padding_len -= 4;
} else {
padding_len = 1;
}
}
if (padding_len != 0) {
uint8_t *padding_bytes;
if (!CBB_add_u16(&extensions, TLSEXT_TYPE_padding) ||
!CBB_add_u16(&extensions, padding_len) ||
!CBB_add_space(&extensions, &padding_bytes, padding_len)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
OPENSSL_memset(padding_bytes, 0, padding_len);
}
}
// The PSK extension must be last, including after the padding.
if (!ext_pre_shared_key_add_clienthello(hs, &extensions)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
// Discard empty extensions blocks.
if (CBB_len(&extensions) == 0) {
CBB_discard_child(out);
}
return CBB_flush(out);
}
bool ssl_add_serverhello_tlsext(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
CBB extensions;
if (!CBB_add_u16_length_prefixed(out, &extensions)) {
goto err;
}
for (unsigned i = 0; i < kNumExtensions; i++) {
if (!(hs->extensions.received & (1u << i))) {
// Don't send extensions that were not received.
continue;
}
if (!kExtensions[i].add_serverhello(hs, &extensions)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
goto err;
}
}
// Discard empty extensions blocks before TLS 1.3.
if (ssl_protocol_version(ssl) < TLS1_3_VERSION &&
CBB_len(&extensions) == 0) {
CBB_discard_child(out);
}
return CBB_flush(out);
err:
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
static bool ssl_scan_clienthello_tlsext(SSL_HANDSHAKE *hs,
const SSL_CLIENT_HELLO *client_hello,
int *out_alert) {
for (size_t i = 0; i < kNumExtensions; i++) {
if (kExtensions[i].init != NULL) {
kExtensions[i].init(hs);
}
}
hs->extensions.received = 0;
CBS extensions;
CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len);
while (CBS_len(&extensions) != 0) {
uint16_t type;
CBS extension;
// Decode the next extension.
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
unsigned ext_index;
const struct tls_extension *const ext =
tls_extension_find(&ext_index, type);
if (ext == NULL) {
continue;
}
hs->extensions.received |= (1u << ext_index);
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ext->parse_clienthello(hs, &alert, &extension)) {
*out_alert = alert;
OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)type);
return false;
}
}
for (size_t i = 0; i < kNumExtensions; i++) {
if (hs->extensions.received & (1u << i)) {
continue;
}
CBS *contents = NULL, fake_contents;
static const uint8_t kFakeRenegotiateExtension[] = {0};
if (kExtensions[i].value == TLSEXT_TYPE_renegotiate &&
ssl_client_cipher_list_contains_cipher(client_hello,
SSL3_CK_SCSV & 0xffff)) {
// The renegotiation SCSV was received so pretend that we received a
// renegotiation extension.
CBS_init(&fake_contents, kFakeRenegotiateExtension,
sizeof(kFakeRenegotiateExtension));
contents = &fake_contents;
hs->extensions.received |= (1u << i);
}
// Extension wasn't observed so call the callback with a NULL
// parameter.
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!kExtensions[i].parse_clienthello(hs, &alert, contents)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
*out_alert = alert;
return false;
}
}
return true;
}
bool ssl_parse_clienthello_tlsext(SSL_HANDSHAKE *hs,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
int alert = SSL_AD_DECODE_ERROR;
if (!ssl_scan_clienthello_tlsext(hs, client_hello, &alert)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return false;
}
if (!ssl_check_clienthello_tlsext(hs)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_TLSEXT);
return false;
}
return true;
}
static bool ssl_scan_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs,
int *out_alert) {
SSL *const ssl = hs->ssl;
// Before TLS 1.3, ServerHello extensions blocks may be omitted if empty.
if (CBS_len(cbs) == 0 && ssl_protocol_version(ssl) < TLS1_3_VERSION) {
return true;
}
// Decode the extensions block and check it is valid.
CBS extensions;
if (!CBS_get_u16_length_prefixed(cbs, &extensions) ||
!tls1_check_duplicate_extensions(&extensions)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
uint32_t received = 0;
while (CBS_len(&extensions) != 0) {
uint16_t type;
CBS extension;
// Decode the next extension.
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
unsigned ext_index;
const struct tls_extension *const ext =
tls_extension_find(&ext_index, type);
if (ext == NULL) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)type);
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return false;
}
static_assert(kNumExtensions <= sizeof(hs->extensions.sent) * 8,
"too many bits");
if (!(hs->extensions.sent & (1u << ext_index))) {
// If the extension was never sent then it is illegal.
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
ERR_add_error_dataf("extension :%u", (unsigned)type);
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return false;
}
received |= (1u << ext_index);
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ext->parse_serverhello(hs, &alert, &extension)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)type);
*out_alert = alert;
return false;
}
}
for (size_t i = 0; i < kNumExtensions; i++) {
if (!(received & (1u << i))) {
// Extension wasn't observed so call the callback with a NULL
// parameter.
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!kExtensions[i].parse_serverhello(hs, &alert, NULL)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
*out_alert = alert;
return false;
}
}
}
return true;
}
static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (ssl->s3->token_binding_negotiated &&
!(SSL_get_secure_renegotiation_support(ssl) &&
SSL_get_extms_support(ssl))) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_TB_WITHOUT_EMS_OR_RI);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
return false;
}
int ret = SSL_TLSEXT_ERR_NOACK;
int al = SSL_AD_UNRECOGNIZED_NAME;
if (ssl->ctx->servername_callback != 0) {
ret = ssl->ctx->servername_callback(ssl, &al, ssl->ctx->servername_arg);
} else if (ssl->session_ctx->servername_callback != 0) {
ret = ssl->session_ctx->servername_callback(
ssl, &al, ssl->session_ctx->servername_arg);
}
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
ssl_send_alert(ssl, SSL3_AL_FATAL, al);
return false;
case SSL_TLSEXT_ERR_NOACK:
hs->should_ack_sni = false;
return true;
default:
return true;
}
}
static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// ALPS and ALPN have a dependency between each other, so we defer checking
// consistency to after the callbacks run.
if (hs->new_session != nullptr && hs->new_session->has_application_settings) {
// ALPN must be negotiated.
if (ssl->s3->alpn_selected.empty()) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_ALPS_WITHOUT_ALPN);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return false;
}
// The negotiated protocol must be one of the ones we advertised for ALPS.
Span<const uint8_t> settings;
if (!ssl_get_local_application_settings(hs, &settings,
ssl->s3->alpn_selected)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return false;
}
if (!hs->new_session->local_application_settings.CopyFrom(settings)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return false;
}
}
return true;
}
bool ssl_parse_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs) {
SSL *const ssl = hs->ssl;
int alert = SSL_AD_DECODE_ERROR;
if (!ssl_scan_serverhello_tlsext(hs, cbs, &alert)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return false;
}
if (!ssl_check_serverhello_tlsext(hs)) {
return false;
}
return true;
}
static enum ssl_ticket_aead_result_t decrypt_ticket_with_cipher_ctx(
Array<uint8_t> *out, EVP_CIPHER_CTX *cipher_ctx, HMAC_CTX *hmac_ctx,
Span<const uint8_t> ticket) {
size_t iv_len = EVP_CIPHER_CTX_iv_length(cipher_ctx);
// Check the MAC at the end of the ticket.
uint8_t mac[EVP_MAX_MD_SIZE];
size_t mac_len = HMAC_size(hmac_ctx);
if (ticket.size() < SSL_TICKET_KEY_NAME_LEN + iv_len + 1 + mac_len) {
// The ticket must be large enough for key name, IV, data, and MAC.
return ssl_ticket_aead_ignore_ticket;
}
// Split the ticket into the ticket and the MAC.
auto ticket_mac = ticket.subspan(ticket.size() - mac_len);
ticket = ticket.subspan(0, ticket.size() - mac_len);
HMAC_Update(hmac_ctx, ticket.data(), ticket.size());
HMAC_Final(hmac_ctx, mac, NULL);
assert(mac_len == ticket_mac.size());
bool mac_ok = CRYPTO_memcmp(mac, ticket_mac.data(), mac_len) == 0;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
mac_ok = true;
#endif
if (!mac_ok) {
return ssl_ticket_aead_ignore_ticket;
}
// Decrypt the session data.
auto ciphertext = ticket.subspan(SSL_TICKET_KEY_NAME_LEN + iv_len);
Array<uint8_t> plaintext;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
if (!plaintext.CopyFrom(ciphertext)) {
return ssl_ticket_aead_error;
}
#else
if (ciphertext.size() >= INT_MAX) {
return ssl_ticket_aead_ignore_ticket;
}
if (!plaintext.Init(ciphertext.size())) {
return ssl_ticket_aead_error;
}
int len1, len2;
if (!EVP_DecryptUpdate(cipher_ctx, plaintext.data(), &len1, ciphertext.data(),
(int)ciphertext.size()) ||
!EVP_DecryptFinal_ex(cipher_ctx, plaintext.data() + len1, &len2)) {
ERR_clear_error();
return ssl_ticket_aead_ignore_ticket;
}
plaintext.Shrink(static_cast<size_t>(len1) + len2);
#endif
*out = std::move(plaintext);
return ssl_ticket_aead_success;
}
static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_cb(
SSL_HANDSHAKE *hs, Array<uint8_t> *out, bool *out_renew_ticket,
Span<const uint8_t> ticket) {
assert(ticket.size() >= SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH);
ScopedEVP_CIPHER_CTX cipher_ctx;
ScopedHMAC_CTX hmac_ctx;
auto name = ticket.subspan(0, SSL_TICKET_KEY_NAME_LEN);
// The actual IV is shorter, but the length is determined by the callback's
// chosen cipher. Instead we pass in |EVP_MAX_IV_LENGTH| worth of IV to ensure
// the callback has enough.
auto iv = ticket.subspan(SSL_TICKET_KEY_NAME_LEN, EVP_MAX_IV_LENGTH);
int cb_ret = hs->ssl->session_ctx->ticket_key_cb(
hs->ssl, const_cast<uint8_t *>(name.data()),
const_cast<uint8_t *>(iv.data()), cipher_ctx.get(), hmac_ctx.get(),
0 /* decrypt */);
if (cb_ret < 0) {
return ssl_ticket_aead_error;
} else if (cb_ret == 0) {
return ssl_ticket_aead_ignore_ticket;
} else if (cb_ret == 2) {
*out_renew_ticket = true;
} else {
assert(cb_ret == 1);
}
return decrypt_ticket_with_cipher_ctx(out, cipher_ctx.get(), hmac_ctx.get(),
ticket);
}
static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_ticket_keys(
SSL_HANDSHAKE *hs, Array<uint8_t> *out, Span<const uint8_t> ticket) {
assert(ticket.size() >= SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH);
SSL_CTX *ctx = hs->ssl->session_ctx.get();
// Rotate the ticket key if necessary.
if (!ssl_ctx_rotate_ticket_encryption_key(ctx)) {
return ssl_ticket_aead_error;
}
const EVP_CIPHER *cipher = EVP_aes_128_cbc();
auto name = ticket.subspan(0, SSL_TICKET_KEY_NAME_LEN);
auto iv =
ticket.subspan(SSL_TICKET_KEY_NAME_LEN, EVP_CIPHER_iv_length(cipher));
// Pick the matching ticket key and decrypt.
ScopedEVP_CIPHER_CTX cipher_ctx;
ScopedHMAC_CTX hmac_ctx;
{
MutexReadLock lock(&ctx->lock);
const TicketKey *key;
if (ctx->ticket_key_current && name == ctx->ticket_key_current->name) {
key = ctx->ticket_key_current.get();
} else if (ctx->ticket_key_prev && name == ctx->ticket_key_prev->name) {
key = ctx->ticket_key_prev.get();
} else {
return ssl_ticket_aead_ignore_ticket;
}
if (!HMAC_Init_ex(hmac_ctx.get(), key->hmac_key, sizeof(key->hmac_key),
tlsext_tick_md(), NULL) ||
!EVP_DecryptInit_ex(cipher_ctx.get(), cipher, NULL,
key->aes_key, iv.data())) {
return ssl_ticket_aead_error;
}
}
return decrypt_ticket_with_cipher_ctx(out, cipher_ctx.get(), hmac_ctx.get(),
ticket);
}
static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_method(
SSL_HANDSHAKE *hs, Array<uint8_t> *out, bool *out_renew_ticket,
Span<const uint8_t> ticket) {
Array<uint8_t> plaintext;
if (!plaintext.Init(ticket.size())) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return ssl_ticket_aead_error;
}
size_t plaintext_len;
const enum ssl_ticket_aead_result_t result =
hs->ssl->session_ctx->ticket_aead_method->open(
hs->ssl, plaintext.data(), &plaintext_len, ticket.size(),
ticket.data(), ticket.size());
if (result != ssl_ticket_aead_success) {
return result;
}
plaintext.Shrink(plaintext_len);
*out = std::move(plaintext);
return ssl_ticket_aead_success;
}
enum ssl_ticket_aead_result_t ssl_process_ticket(
SSL_HANDSHAKE *hs, UniquePtr<SSL_SESSION> *out_session,
bool *out_renew_ticket, Span<const uint8_t> ticket,
Span<const uint8_t> session_id) {
*out_renew_ticket = false;
out_session->reset();
if ((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) ||
session_id.size() > SSL_MAX_SSL_SESSION_ID_LENGTH) {
return ssl_ticket_aead_ignore_ticket;
}
Array<uint8_t> plaintext;
enum ssl_ticket_aead_result_t result;
if (hs->ssl->session_ctx->ticket_aead_method != NULL) {
result = ssl_decrypt_ticket_with_method(hs, &plaintext, out_renew_ticket,
ticket);
} else {
// Ensure there is room for the key name and the largest IV |ticket_key_cb|
// may try to consume. The real limit may be lower, but the maximum IV
// length should be well under the minimum size for the session material and
// HMAC.
if (ticket.size() < SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH) {
return ssl_ticket_aead_ignore_ticket;
}
if (hs->ssl->session_ctx->ticket_key_cb != NULL) {
result =
ssl_decrypt_ticket_with_cb(hs, &plaintext, out_renew_ticket, ticket);
} else {
result = ssl_decrypt_ticket_with_ticket_keys(hs, &plaintext, ticket);
}
}
if (result != ssl_ticket_aead_success) {
return result;
}
// Decode the session.
UniquePtr<SSL_SESSION> session(SSL_SESSION_from_bytes(
plaintext.data(), plaintext.size(), hs->ssl->ctx.get()));
if (!session) {
ERR_clear_error(); // Don't leave an error on the queue.
return ssl_ticket_aead_ignore_ticket;
}
// Copy the client's session ID into the new session, to denote the ticket has
// been accepted.
OPENSSL_memcpy(session->session_id, session_id.data(), session_id.size());
session->session_id_length = session_id.size();
*out_session = std::move(session);
return ssl_ticket_aead_success;
}
bool tls1_parse_peer_sigalgs(SSL_HANDSHAKE *hs, const CBS *in_sigalgs) {
// Extension ignored for inappropriate versions
if (ssl_protocol_version(hs->ssl) < TLS1_2_VERSION) {
return true;
}
// In all contexts, the signature algorithms list may not be empty. (It may be
// omitted by clients in TLS 1.2, but then the entire extension is omitted.)
return CBS_len(in_sigalgs) != 0 &&
parse_u16_array(in_sigalgs, &hs->peer_sigalgs);
}
bool tls1_get_legacy_signature_algorithm(uint16_t *out, const EVP_PKEY *pkey) {
switch (EVP_PKEY_id(pkey)) {
case EVP_PKEY_RSA:
*out = SSL_SIGN_RSA_PKCS1_MD5_SHA1;
return true;
case EVP_PKEY_EC:
*out = SSL_SIGN_ECDSA_SHA1;
return true;
default:
return false;
}
}
bool tls1_choose_signature_algorithm(SSL_HANDSHAKE *hs, uint16_t *out) {
SSL *const ssl = hs->ssl;
CERT *cert = hs->config->cert.get();
DC *dc = cert->dc.get();
// Before TLS 1.2, the signature algorithm isn't negotiated as part of the
// handshake.
if (ssl_protocol_version(ssl) < TLS1_2_VERSION) {
if (!tls1_get_legacy_signature_algorithm(out, hs->local_pubkey.get())) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
return false;
}
return true;
}
Span<const uint16_t> sigalgs = kSignSignatureAlgorithms;
if (ssl_signing_with_dc(hs)) {
sigalgs = MakeConstSpan(&dc->expected_cert_verify_algorithm, 1);
} else if (!cert->sigalgs.empty()) {
sigalgs = cert->sigalgs;
}
Span<const uint16_t> peer_sigalgs = tls1_get_peer_verify_algorithms(hs);
for (uint16_t sigalg : sigalgs) {
// SSL_SIGN_RSA_PKCS1_MD5_SHA1 is an internal value and should never be
// negotiated.
if (sigalg == SSL_SIGN_RSA_PKCS1_MD5_SHA1 ||
!ssl_private_key_supports_signature_algorithm(hs, sigalg)) {
continue;
}
for (uint16_t peer_sigalg : peer_sigalgs) {
if (sigalg == peer_sigalg) {
*out = sigalg;
return true;
}
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
return false;
}
Span<const uint16_t> tls1_get_peer_verify_algorithms(const SSL_HANDSHAKE *hs) {
Span<const uint16_t> peer_sigalgs = hs->peer_sigalgs;
if (peer_sigalgs.empty() && ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
// If the client didn't specify any signature_algorithms extension then
// we can assume that it supports SHA1. See
// http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
static const uint16_t kDefaultPeerAlgorithms[] = {SSL_SIGN_RSA_PKCS1_SHA1,
SSL_SIGN_ECDSA_SHA1};
peer_sigalgs = kDefaultPeerAlgorithms;
}
return peer_sigalgs;
}
bool tls1_verify_channel_id(SSL_HANDSHAKE *hs, const SSLMessage &msg) {
SSL *const ssl = hs->ssl;
// A Channel ID handshake message is structured to contain multiple
// extensions, but the only one that can be present is Channel ID.
uint16_t extension_type;
CBS channel_id = msg.body, extension;
if (!CBS_get_u16(&channel_id, &extension_type) ||
!CBS_get_u16_length_prefixed(&channel_id, &extension) ||
CBS_len(&channel_id) != 0 ||
extension_type != TLSEXT_TYPE_channel_id ||
CBS_len(&extension) != TLSEXT_CHANNEL_ID_SIZE) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return false;
}
UniquePtr<EC_GROUP> p256(EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1));
if (!p256) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_P256_SUPPORT);
return false;
}
UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new());
UniquePtr<BIGNUM> x(BN_new()), y(BN_new());
if (!sig || !x || !y) {
return false;
}
const uint8_t *p = CBS_data(&extension);
if (BN_bin2bn(p + 0, 32, x.get()) == NULL ||
BN_bin2bn(p + 32, 32, y.get()) == NULL ||
BN_bin2bn(p + 64, 32, sig->r) == NULL ||
BN_bin2bn(p + 96, 32, sig->s) == NULL) {
return false;
}
UniquePtr<EC_KEY> key(EC_KEY_new());
UniquePtr<EC_POINT> point(EC_POINT_new(p256.get()));
if (!key || !point ||
!EC_POINT_set_affine_coordinates_GFp(p256.get(), point.get(), x.get(),
y.get(), nullptr) ||
!EC_KEY_set_group(key.get(), p256.get()) ||
!EC_KEY_set_public_key(key.get(), point.get())) {
return false;
}
uint8_t digest[EVP_MAX_MD_SIZE];
size_t digest_len;
if (!tls1_channel_id_hash(hs, digest, &digest_len)) {
return false;
}
bool sig_ok = ECDSA_do_verify(digest, digest_len, sig.get(), key.get());
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
sig_ok = true;
ERR_clear_error();
#endif
if (!sig_ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_SIGNATURE_INVALID);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
ssl->s3->channel_id_valid = false;
return false;
}
OPENSSL_memcpy(ssl->s3->channel_id, p, 64);
return true;
}
bool tls1_write_channel_id(SSL_HANDSHAKE *hs, CBB *cbb) {
uint8_t digest[EVP_MAX_MD_SIZE];
size_t digest_len;
if (!tls1_channel_id_hash(hs, digest, &digest_len)) {
return false;
}
EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(hs->config->channel_id_private.get());
if (ec_key == nullptr) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
UniquePtr<BIGNUM> x(BN_new()), y(BN_new());
if (!x || !y ||
!EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(ec_key),
EC_KEY_get0_public_key(ec_key),
x.get(), y.get(), nullptr)) {
return false;
}
UniquePtr<ECDSA_SIG> sig(ECDSA_do_sign(digest, digest_len, ec_key));
if (!sig) {
return false;
}
CBB child;
if (!CBB_add_u16(cbb, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16_length_prefixed(cbb, &child) ||
!BN_bn2cbb_padded(&child, 32, x.get()) ||
!BN_bn2cbb_padded(&child, 32, y.get()) ||
!BN_bn2cbb_padded(&child, 32, sig->r) ||
!BN_bn2cbb_padded(&child, 32, sig->s) ||
!CBB_flush(cbb)) {
return false;
}
return true;
}
bool tls1_channel_id_hash(SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len) {
SSL *const ssl = hs->ssl;
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
Array<uint8_t> msg;
if (!tls13_get_cert_verify_signature_input(hs, &msg,
ssl_cert_verify_channel_id)) {
return false;
}
SHA256(msg.data(), msg.size(), out);
*out_len = SHA256_DIGEST_LENGTH;
return true;
}
SHA256_CTX ctx;
SHA256_Init(&ctx);
static const char kClientIDMagic[] = "TLS Channel ID signature";
SHA256_Update(&ctx, kClientIDMagic, sizeof(kClientIDMagic));
if (ssl->session != NULL) {
static const char kResumptionMagic[] = "Resumption";
SHA256_Update(&ctx, kResumptionMagic, sizeof(kResumptionMagic));
if (ssl->session->original_handshake_hash_len == 0) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return false;
}
SHA256_Update(&ctx, ssl->session->original_handshake_hash,
ssl->session->original_handshake_hash_len);
}
uint8_t hs_hash[EVP_MAX_MD_SIZE];
size_t hs_hash_len;
if (!hs->transcript.GetHash(hs_hash, &hs_hash_len)) {
return false;
}
SHA256_Update(&ctx, hs_hash, (size_t)hs_hash_len);
SHA256_Final(out, &ctx);
*out_len = SHA256_DIGEST_LENGTH;
return true;
}
bool tls1_record_handshake_hashes_for_channel_id(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// This function should never be called for a resumed session because the
// handshake hashes that we wish to record are for the original, full
// handshake.
if (ssl->session != NULL) {
return false;
}
static_assert(
sizeof(hs->new_session->original_handshake_hash) == EVP_MAX_MD_SIZE,
"original_handshake_hash is too small");
size_t digest_len;
if (!hs->transcript.GetHash(hs->new_session->original_handshake_hash,
&digest_len)) {
return false;
}
static_assert(EVP_MAX_MD_SIZE <= 0xff,
"EVP_MAX_MD_SIZE does not fit in uint8_t");
hs->new_session->original_handshake_hash_len = (uint8_t)digest_len;
return true;
}
bool ssl_do_channel_id_callback(SSL_HANDSHAKE *hs) {
if (hs->config->channel_id_private != NULL ||
hs->ssl->ctx->channel_id_cb == NULL) {
return true;
}
EVP_PKEY *key = NULL;
hs->ssl->ctx->channel_id_cb(hs->ssl, &key);
if (key == NULL) {
// The caller should try again later.
return true;
}
UniquePtr<EVP_PKEY> free_key(key);
return SSL_set1_tls_channel_id(hs->ssl, key);
}
bool ssl_is_sct_list_valid(const CBS *contents) {
// Shallow parse the SCT list for sanity. By the RFC
// (https://tools.ietf.org/html/rfc6962#section-3.3) neither the list nor any
// of the SCTs may be empty.
CBS copy = *contents;
CBS sct_list;
if (!CBS_get_u16_length_prefixed(&copy, &sct_list) ||
CBS_len(&copy) != 0 ||
CBS_len(&sct_list) == 0) {
return false;
}
while (CBS_len(&sct_list) > 0) {
CBS sct;
if (!CBS_get_u16_length_prefixed(&sct_list, &sct) ||
CBS_len(&sct) == 0) {
return false;
}
}
return true;
}
BSSL_NAMESPACE_END
using namespace bssl;
int SSL_early_callback_ctx_extension_get(const SSL_CLIENT_HELLO *client_hello,
uint16_t extension_type,
const uint8_t **out_data,
size_t *out_len) {
CBS cbs;
if (!ssl_client_hello_get_extension(client_hello, &cbs, extension_type)) {
return 0;
}
*out_data = CBS_data(&cbs);
*out_len = CBS_len(&cbs);
return 1;
}