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boringssl / boringssl / 1252f8758ab1c4c4a14db25f9fa53e5950e4bcda / . / ssl / t1_lib.c
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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 <openssl/bytestring.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 <openssl/type_check.h>
#include "internal.h"
#include "../crypto/internal.h"
static int ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs);
static int 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 int tls1_check_duplicate_extensions(const CBS *cbs) {
CBS extensions = *cbs;
size_t num_extensions = 0, i = 0;
uint16_t *extension_types = NULL;
int ret = 0;
/* First pass: count the extensions. */
while (CBS_len(&extensions) > 0) {
uint16_t type;
CBS extension;
if (!CBS_get_u16(&extensions, &type) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
goto done;
}
num_extensions++;
}
if (num_extensions == 0) {
return 1;
}
extension_types = OPENSSL_malloc(sizeof(uint16_t) * num_extensions);
if (extension_types == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto done;
}
/* Second pass: gather the extension types. */
extensions = *cbs;
for (i = 0; i < num_extensions; i++) {
CBS extension;
if (!CBS_get_u16(&extensions, &extension_types[i]) ||
!CBS_get_u16_length_prefixed(&extensions, &extension)) {
/* This should not happen. */
goto done;
}
}
assert(CBS_len(&extensions) == 0);
/* Sort the extensions and make sure there are no duplicates. */
qsort(extension_types, num_extensions, sizeof(uint16_t), compare_uint16_t);
for (i = 1; i < num_extensions; i++) {
if (extension_types[i - 1] == extension_types[i]) {
goto done;
}
}
ret = 1;
done:
OPENSSL_free(extension_types);
return ret;
}
int ssl_client_hello_init(SSL *ssl, SSL_CLIENT_HELLO *out, const uint8_t *in,
size_t in_len) {
OPENSSL_memset(out, 0, sizeof(*out));
out->ssl = ssl;
out->client_hello = in;
out->client_hello_len = in_len;
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 0;
}
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 0;
}
}
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 0;
}
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. (E.g. SSLv3.) */
if (CBS_len(&client_hello) == 0) {
out->extensions = NULL;
out->extensions_len = 0;
return 1;
}
/* 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 0;
}
out->extensions = CBS_data(&extensions);
out->extensions_len = CBS_len(&extensions);
return 1;
}
int 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 0;
}
if (type == extension_type) {
*out = extension;
return 1;
}
}
return 0;
}
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;
}
static const uint16_t kDefaultGroups[] = {
SSL_CURVE_X25519,
SSL_CURVE_SECP256R1,
SSL_CURVE_SECP384R1,
};
void tls1_get_grouplist(SSL *ssl, const uint16_t **out_group_ids,
size_t *out_group_ids_len) {
*out_group_ids = ssl->supported_group_list;
*out_group_ids_len = ssl->supported_group_list_len;
if (!*out_group_ids) {
*out_group_ids = kDefaultGroups;
*out_group_ids_len = OPENSSL_ARRAY_SIZE(kDefaultGroups);
}
}
int tls1_get_shared_group(SSL_HANDSHAKE *hs, uint16_t *out_group_id) {
SSL *const ssl = hs->ssl;
assert(ssl->server);
const uint16_t *groups, *pref, *supp;
size_t groups_len, pref_len, supp_len;
tls1_get_grouplist(ssl, &groups, &groups_len);
/* 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|. */
if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) {
pref = groups;
pref_len = groups_len;
supp = hs->peer_supported_group_list;
supp_len = hs->peer_supported_group_list_len;
} else {
pref = hs->peer_supported_group_list;
pref_len = hs->peer_supported_group_list_len;
supp = groups;
supp_len = groups_len;
}
for (size_t i = 0; i < pref_len; i++) {
for (size_t j = 0; j < supp_len; j++) {
if (pref[i] == supp[j]) {
*out_group_id = pref[i];
return 1;
}
}
}
return 0;
}
int tls1_set_curves(uint16_t **out_group_ids, size_t *out_group_ids_len,
const int *curves, size_t ncurves) {
uint16_t *group_ids;
group_ids = OPENSSL_malloc(ncurves * sizeof(uint16_t));
if (group_ids == NULL) {
return 0;
}
for (size_t i = 0; i < ncurves; i++) {
if (!ssl_nid_to_group_id(&group_ids[i], curves[i])) {
OPENSSL_free(group_ids);
return 0;
}
}
OPENSSL_free(*out_group_ids);
*out_group_ids = group_ids;
*out_group_ids_len = ncurves;
return 1;
}
int tls1_set_curves_list(uint16_t **out_group_ids, size_t *out_group_ids_len,
const char *curves) {
uint16_t *group_ids = NULL;
size_t ncurves = 0;
const char *col;
const char *ptr = curves;
do {
col = strchr(ptr, ':');
uint16_t group_id;
if (!ssl_name_to_group_id(&group_id, ptr,
col ? (size_t)(col - ptr) : strlen(ptr))) {
goto err;
}
uint16_t *new_group_ids = OPENSSL_realloc(group_ids,
(ncurves + 1) * sizeof(uint16_t));
if (new_group_ids == NULL) {
goto err;
}
group_ids = new_group_ids;
group_ids[ncurves] = group_id;
ncurves++;
if (col) {
ptr = col + 1;
}
} while (col);
OPENSSL_free(*out_group_ids);
*out_group_ids = group_ids;
*out_group_ids_len = ncurves;
return 1;
err:
OPENSSL_free(group_ids);
return 0;
}
int tls1_check_group_id(SSL *ssl, uint16_t group_id) {
const uint16_t *groups;
size_t groups_len;
tls1_get_grouplist(ssl, &groups, &groups_len);
for (size_t i = 0; i < groups_len; i++) {
if (groups[i] == group_id) {
return 1;
}
}
return 0;
}
/* kVerifySignatureAlgorithms is the default list of accepted signature
* algorithms for verifying.
*
* For now, RSA-PSS signature algorithms are not enabled on Android's system
* BoringSSL. Once the change in Chrome has stuck and the values are finalized,
* restore them. */
static const uint16_t kVerifySignatureAlgorithms[] = {
/* Prefer SHA-256 algorithms. */
SSL_SIGN_ECDSA_SECP256R1_SHA256,
#if !defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_RSA_PSS_SHA256,
#endif
SSL_SIGN_RSA_PKCS1_SHA256,
/* Larger hashes are acceptable. */
SSL_SIGN_ECDSA_SECP384R1_SHA384,
#if !defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_RSA_PSS_SHA384,
#endif
SSL_SIGN_RSA_PKCS1_SHA384,
/* TODO(davidben): Remove this. */
#if defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_ECDSA_SECP521R1_SHA512,
#endif
#if !defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_RSA_PSS_SHA512,
#endif
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.
*
* For now, RSA-PSS signature algorithms are not enabled on Android's system
* BoringSSL. Once the change in Chrome has stuck and the values are finalized,
* restore them. */
static const uint16_t kSignSignatureAlgorithms[] = {
/* Prefer SHA-256 algorithms. */
SSL_SIGN_ECDSA_SECP256R1_SHA256,
#if !defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_RSA_PSS_SHA256,
#endif
SSL_SIGN_RSA_PKCS1_SHA256,
/* If needed, sign larger hashes.
*
* TODO(davidben): Determine which of these may be pruned. */
SSL_SIGN_ECDSA_SECP384R1_SHA384,
#if !defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_RSA_PSS_SHA384,
#endif
SSL_SIGN_RSA_PKCS1_SHA384,
SSL_SIGN_ECDSA_SECP521R1_SHA512,
#if !defined(BORINGSSL_ANDROID_SYSTEM)
SSL_SIGN_RSA_PSS_SHA512,
#endif
SSL_SIGN_RSA_PKCS1_SHA512,
/* If the peer supports nothing else, sign with SHA-1. */
SSL_SIGN_ECDSA_SHA1,
SSL_SIGN_RSA_PKCS1_SHA1,
};
size_t tls12_get_verify_sigalgs(const SSL *ssl, const uint16_t **out) {
*out = kVerifySignatureAlgorithms;
return OPENSSL_ARRAY_SIZE(kVerifySignatureAlgorithms);
}
int tls12_check_peer_sigalg(SSL *ssl, int *out_alert, uint16_t sigalg) {
const uint16_t *verify_sigalgs;
size_t num_verify_sigalgs = tls12_get_verify_sigalgs(ssl, &verify_sigalgs);
for (size_t i = 0; i < num_verify_sigalgs; i++) {
if (sigalg == verify_sigalgs[i]) {
return 1;
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
/* Get a mask of disabled algorithms: an algorithm is disabled if it isn't
* supported or doesn't appear in supported signature algorithms. Unlike
* ssl_cipher_get_disabled this applies to a specific session and not global
* settings. */
void ssl_set_client_disabled(SSL *ssl) {
CERT *c = ssl->cert;
int have_rsa = 0, have_ecdsa = 0;
c->mask_a = 0;
c->mask_k = 0;
/* Now go through all signature algorithms seeing if we support any for RSA or
* ECDSA. Do this for all versions not just TLS 1.2. */
const uint16_t *sigalgs;
size_t num_sigalgs = tls12_get_verify_sigalgs(ssl, &sigalgs);
for (size_t i = 0; i < num_sigalgs; i++) {
switch (sigalgs[i]) {
case SSL_SIGN_RSA_PSS_SHA512:
case SSL_SIGN_RSA_PSS_SHA384:
case SSL_SIGN_RSA_PSS_SHA256:
case SSL_SIGN_RSA_PKCS1_SHA512:
case SSL_SIGN_RSA_PKCS1_SHA384:
case SSL_SIGN_RSA_PKCS1_SHA256:
case SSL_SIGN_RSA_PKCS1_SHA1:
have_rsa = 1;
break;
case SSL_SIGN_ECDSA_SECP521R1_SHA512:
case SSL_SIGN_ECDSA_SECP384R1_SHA384:
case SSL_SIGN_ECDSA_SECP256R1_SHA256:
case SSL_SIGN_ECDSA_SHA1:
have_ecdsa = 1;
break;
}
}
/* Disable auth if we don't include any appropriate signature algorithms. */
if (!have_rsa) {
c->mask_a |= SSL_aRSA;
}
if (!have_ecdsa) {
c->mask_a |= SSL_aECDSA;
}
/* with PSK there must be client callback set */
if (!ssl->psk_client_callback) {
c->mask_a |= SSL_aPSK;
c->mask_k |= SSL_kPSK;
}
}
/* 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 one for success and zero 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);
int (*add_clienthello)(SSL_HANDSHAKE *hs, CBB *out);
int (*parse_serverhello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents);
int (*parse_clienthello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents);
int (*add_serverhello)(SSL_HANDSHAKE *hs, CBB *out);
};
static int 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 0;
}
return 1;
}
static int ignore_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
/* This extension from the client is handled elsewhere. */
return 1;
}
static int dont_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
return 1;
}
/* Server name indication (SNI).
*
* https://tools.ietf.org/html/rfc6066#section-3. */
static int ext_sni_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->tlsext_hostname == NULL) {
return 1;
}
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->tlsext_hostname,
strlen(ssl->tlsext_hostname)) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
static int ext_sni_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
if (CBS_len(contents) != 0) {
return 0;
}
assert(ssl->tlsext_hostname != NULL);
if (ssl->session == NULL) {
assert(ssl->s3->new_session->tlsext_hostname == NULL);
ssl->s3->new_session->tlsext_hostname = BUF_strdup(ssl->tlsext_hostname);
if (!ssl->s3->new_session->tlsext_hostname) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
}
return 1;
}
static int ext_sni_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return 1;
}
CBS server_name_list, host_name;
uint8_t name_type;
if (!CBS_get_u16_length_prefixed(contents, &server_name_list) ||
!CBS_get_u8(&server_name_list, &name_type) ||
/* Although the server_name extension was intended to be extensible to
* new name types and multiple names, OpenSSL 1.0.x had a bug which meant
* different name types will cause an error. Further, RFC 4366 originally
* defined syntax inextensibly. RFC 6066 corrected this mistake, but
* adding new name types is no longer feasible.
*
* Act as if the extensibility does not exist to simplify parsing. */
!CBS_get_u16_length_prefixed(&server_name_list, &host_name) ||
CBS_len(&server_name_list) != 0 ||
CBS_len(contents) != 0) {
return 0;
}
if (name_type != TLSEXT_NAMETYPE_host_name ||
CBS_len(&host_name) == 0 ||
CBS_len(&host_name) > TLSEXT_MAXLEN_host_name ||
CBS_contains_zero_byte(&host_name)) {
*out_alert = SSL_AD_UNRECOGNIZED_NAME;
return 0;
}
/* Copy the hostname as a string. */
if (!CBS_strdup(&host_name, &hs->hostname)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
hs->should_ack_sni = 1;
return 1;
}
static int ext_sni_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->ssl->s3->session_reused ||
!hs->should_ack_sni) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
/* Renegotiation indication.
*
* https://tools.ietf.org/html/rfc5746 */
static int ext_ri_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
/* Renegotiation indication is not necessary in TLS 1.3. */
if (min_version >= TLS1_3_VERSION) {
return 1;
}
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 0;
}
return 1;
}
static int ext_ri_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents != NULL && ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 0;
}
/* 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 0;
}
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 1;
}
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 0;
}
/* 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 0;
}
const uint8_t *d = CBS_data(&renegotiated_connection);
if (CRYPTO_memcmp(d, ssl->s3->previous_client_finished,
ssl->s3->previous_client_finished_len)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_HANDSHAKE_FAILURE;
return 0;
}
d += ssl->s3->previous_client_finished_len;
if (CRYPTO_memcmp(d, ssl->s3->previous_server_finished,
ssl->s3->previous_server_finished_len)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
ssl->s3->send_connection_binding = 1;
return 1;
}
static int 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 (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 1;
}
if (contents == NULL) {
return 1;
}
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 0;
}
/* 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 0;
}
ssl->s3->send_connection_binding = 1;
return 1;
}
static int 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 (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
!CBB_add_u16(out, 1 /* length */) ||
!CBB_add_u8(out, 0 /* empty renegotiation info */)) {
return 0;
}
return 1;
}
/* Extended Master Secret.
*
* https://tools.ietf.org/html/rfc7627 */
static int ext_ems_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
uint16_t min_version, max_version;
if (!ssl_get_version_range(hs->ssl, &min_version, &max_version)) {
return 0;
}
/* Extended master secret is not necessary in TLS 1.3. */
if (min_version >= TLS1_3_VERSION || max_version <= SSL3_VERSION) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
static int ext_ems_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
/* Whether EMS is negotiated may not change on renegotation. */
if (ssl->s3->initial_handshake_complete) {
if ((contents != NULL) != ssl->s3->tmp.extended_master_secret) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_EMS_MISMATCH);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
return 1;
}
if (contents == NULL) {
return 1;
}
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION ||
ssl->version == SSL3_VERSION) {
return 0;
}
if (CBS_len(contents) != 0) {
return 0;
}
ssl->s3->tmp.extended_master_secret = 1;
return 1;
}
static int ext_ems_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
uint16_t version = ssl3_protocol_version(ssl);
if (version >= TLS1_3_VERSION ||
version == SSL3_VERSION) {
return 1;
}
if (contents == NULL) {
return 1;
}
if (CBS_len(contents) != 0) {
return 0;
}
ssl->s3->tmp.extended_master_secret = 1;
return 1;
}
static int ext_ems_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ssl->s3->tmp.extended_master_secret) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
/* Session tickets.
*
* https://tools.ietf.org/html/rfc5077 */
static int ext_ticket_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
/* TLS 1.3 uses a different ticket extension. */
if (min_version >= TLS1_3_VERSION ||
SSL_get_options(ssl) & SSL_OP_NO_TICKET) {
return 1;
}
const uint8_t *ticket_data = NULL;
int ticket_len = 0;
/* 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. */
uint16_t session_version;
if (!ssl->s3->initial_handshake_complete &&
ssl->session != NULL &&
ssl->session->tlsext_tick != NULL &&
/* Don't send TLS 1.3 session tickets in the ticket extension. */
ssl->method->version_from_wire(&session_version,
ssl->session->ssl_version) &&
session_version < TLS1_3_VERSION) {
ticket_data = ssl->session->tlsext_tick;
ticket_len = ssl->session->tlsext_ticklen;
}
CBB ticket;
if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
!CBB_add_u16_length_prefixed(out, &ticket) ||
!CBB_add_bytes(&ticket, ticket_data, ticket_len) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
static int ext_ticket_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 0;
}
/* 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 0;
}
hs->ticket_expected = 1;
return 1;
}
static int ext_ticket_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ticket_expected) {
return 1;
}
/* 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 0;
}
return 1;
}
/* Signature Algorithms.
*
* https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1 */
static int ext_sigalgs_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
if (max_version < TLS1_2_VERSION) {
return 1;
}
const uint16_t *sigalgs;
const size_t num_sigalgs = tls12_get_verify_sigalgs(ssl, &sigalgs);
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)) {
return 0;
}
for (size_t i = 0; i < num_sigalgs; i++) {
if (!CBB_add_u16(&sigalgs_cbb, sigalgs[i])) {
return 0;
}
}
if (!CBB_flush(out)) {
return 0;
}
return 1;
}
static int ext_sigalgs_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
OPENSSL_free(hs->peer_sigalgs);
hs->peer_sigalgs = NULL;
hs->num_peer_sigalgs = 0;
if (contents == NULL) {
return 1;
}
CBS supported_signature_algorithms;
if (!CBS_get_u16_length_prefixed(contents, &supported_signature_algorithms) ||
CBS_len(contents) != 0 ||
CBS_len(&supported_signature_algorithms) == 0 ||
!tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) {
return 0;
}
return 1;
}
/* OCSP Stapling.
*
* https://tools.ietf.org/html/rfc6066#section-8 */
static int ext_ocsp_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!ssl->ocsp_stapling_enabled) {
return 1;
}
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 0;
}
return 1;
}
static int ext_ocsp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
/* TLS 1.3 OCSP responses are included in the Certificate extensions. */
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 0;
}
/* OCSP stapling is forbidden on non-certificate ciphers. */
if (CBS_len(contents) != 0 ||
!ssl_cipher_uses_certificate_auth(ssl->s3->tmp.new_cipher)) {
return 0;
}
/* 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 = 1;
return 1;
}
static int ext_ocsp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return 1;
}
uint8_t status_type;
if (!CBS_get_u8(contents, &status_type)) {
return 0;
}
/* 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 1;
}
static int ext_ocsp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION ||
!hs->ocsp_stapling_requested ||
ssl->ocsp_response == NULL ||
ssl->s3->session_reused ||
!ssl_cipher_uses_certificate_auth(ssl->s3->tmp.new_cipher)) {
return 1;
}
hs->certificate_status_expected = 1;
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 int 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 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
static int ext_npn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 0;
}
/* 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 != NULL) {
/* 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 0;
}
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 0;
}
}
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) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
OPENSSL_free(ssl->s3->next_proto_negotiated);
ssl->s3->next_proto_negotiated = BUF_memdup(selected, selected_len);
if (ssl->s3->next_proto_negotiated == NULL) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
ssl->s3->next_proto_negotiated_len = selected_len;
hs->next_proto_neg_seen = 1;
return 1;
}
static int ext_npn_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 1;
}
if (contents != NULL && CBS_len(contents) != 0) {
return 0;
}
if (contents == NULL ||
ssl->s3->initial_handshake_complete ||
ssl->ctx->next_protos_advertised_cb == NULL ||
SSL_is_dtls(ssl)) {
return 1;
}
hs->next_proto_neg_seen = 1;
return 1;
}
static int 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 1;
}
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 = 0;
return 1;
}
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 0;
}
return 1;
}
/* Signed certificate timestamps.
*
* https://tools.ietf.org/html/rfc6962#section-3.3.1 */
static int ext_sct_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!ssl->signed_cert_timestamps_enabled) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
static int ext_sct_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
/* TLS 1.3 SCTs are included in the Certificate extensions. */
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
/* 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(ssl->signed_cert_timestamps_enabled);
if (!ssl_is_sct_list_valid(contents)) {
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
/* 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 &&
!CBS_stow(
contents,
&ssl->s3->new_session->tlsext_signed_cert_timestamp_list,
&ssl->s3->new_session->tlsext_signed_cert_timestamp_list_length)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
return 1;
}
static int ext_sct_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return 1;
}
if (CBS_len(contents) != 0) {
return 0;
}
hs->scts_requested = 1;
return 1;
}
static int ext_sct_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
/* The extension shouldn't be sent when resuming sessions. */
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION ||
ssl->s3->session_reused ||
ssl->ctx->signed_cert_timestamp_list_length == 0) {
return 1;
}
CBB contents;
return CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) &&
CBB_add_u16_length_prefixed(out, &contents) &&
CBB_add_bytes(&contents, ssl->ctx->signed_cert_timestamp_list,
ssl->ctx->signed_cert_timestamp_list_length) &&
CBB_flush(out);
}
/* Application-level Protocol Negotiation.
*
* https://tools.ietf.org/html/rfc7301 */
static int ext_alpn_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->alpn_client_proto_list == NULL ||
ssl->s3->initial_handshake_complete) {
return 1;
}
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, ssl->alpn_client_proto_list,
ssl->alpn_client_proto_list_len) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
static int ext_alpn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
assert(!ssl->s3->initial_handshake_complete);
assert(ssl->alpn_client_proto_list != NULL);
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 0;
}
/* 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 0;
}
/* Check that the protcol name is one of the ones we advertised. */
int protocol_ok = 0;
CBS client_protocol_name_list, client_protocol_name;
CBS_init(&client_protocol_name_list, ssl->alpn_client_proto_list,
ssl->alpn_client_proto_list_len);
while (CBS_len(&client_protocol_name_list) > 0) {
if (!CBS_get_u8_length_prefixed(&client_protocol_name_list,
&client_protocol_name)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
if (CBS_len(&client_protocol_name) == CBS_len(&protocol_name) &&
OPENSSL_memcmp(CBS_data(&client_protocol_name),
CBS_data(&protocol_name),
CBS_len(&protocol_name)) == 0) {
protocol_ok = 1;
break;
}
}
if (!protocol_ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
if (!CBS_stow(&protocol_name, &ssl->s3->alpn_selected,
&ssl->s3->alpn_selected_len)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
return 1;
}
int 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)) {
/* Ignore ALPN if not configured or no extension was supplied. */
return 1;
}
/* ALPN takes precedence over NPN. */
hs->next_proto_neg_seen = 0;
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 0;
}
/* 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 0;
}
}
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) {
OPENSSL_free(ssl->s3->alpn_selected);
ssl->s3->alpn_selected = BUF_memdup(selected, selected_len);
if (ssl->s3->alpn_selected == NULL) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
ssl->s3->alpn_selected_len = selected_len;
}
return 1;
}
static int ext_alpn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->s3->alpn_selected == NULL) {
return 1;
}
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,
ssl->s3->alpn_selected_len) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
/* Channel ID.
*
* https://tools.ietf.org/html/draft-balfanz-tls-channelid-01 */
static void ext_channel_id_init(SSL_HANDSHAKE *hs) {
hs->ssl->s3->tlsext_channel_id_valid = 0;
}
static int ext_channel_id_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!ssl->tlsext_channel_id_enabled ||
SSL_is_dtls(ssl)) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
static int ext_channel_id_parse_serverhello(SSL_HANDSHAKE *hs,
uint8_t *out_alert, CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
assert(!SSL_is_dtls(ssl));
assert(ssl->tlsext_channel_id_enabled);
if (CBS_len(contents) != 0) {
return 0;
}
ssl->s3->tlsext_channel_id_valid = 1;
return 1;
}
static int ext_channel_id_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert, CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL ||
!ssl->tlsext_channel_id_enabled ||
SSL_is_dtls(ssl)) {
return 1;
}
if (CBS_len(contents) != 0) {
return 0;
}
ssl->s3->tlsext_channel_id_valid = 1;
return 1;
}
static int ext_channel_id_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (!ssl->s3->tlsext_channel_id_valid) {
return 1;
}
if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16(out, 0 /* length */)) {
return 0;
}
return 1;
}
/* Secure Real-time Transport Protocol (SRTP) extension.
*
* https://tools.ietf.org/html/rfc5764 */
static void ext_srtp_init(SSL_HANDSHAKE *hs) {
hs->ssl->srtp_profile = NULL;
}
static int 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) {
return 1;
}
const size_t num_profiles = sk_SRTP_PROTECTION_PROFILE_num(profiles);
if (num_profiles == 0) {
return 1;
}
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 0;
}
for (size_t i = 0; i < num_profiles; i++) {
if (!CBB_add_u16(&profile_ids,
sk_SRTP_PROTECTION_PROFILE_value(profiles, i)->id)) {
return 0;
}
}
if (!CBB_add_u8(&contents, 0 /* empty use_mki value */) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
static int ext_srtp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
/* 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 0;
}
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 0;
}
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 (size_t i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(profiles); i++) {
const SRTP_PROTECTION_PROFILE *profile =
sk_SRTP_PROTECTION_PROFILE_value(profiles, i);
if (profile->id == profile_id) {
ssl->srtp_profile = profile;
return 1;
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
static int ext_srtp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
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 0;
}
/* 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 (size_t i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(server_profiles); i++) {
const SRTP_PROTECTION_PROFILE *server_profile =
sk_SRTP_PROTECTION_PROFILE_value(server_profiles, i);
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 0;
}
if (server_profile->id == profile_id) {
ssl->srtp_profile = server_profile;
return 1;
}
}
}
return 1;
}
static int ext_srtp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl->srtp_profile == NULL) {
return 1;
}
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->srtp_profile->id) ||
!CBB_add_u8(&contents, 0 /* empty MKI */) ||
!CBB_flush(out)) {
return 0;
}
return 1;
}
/* EC point formats.
*
* https://tools.ietf.org/html/rfc4492#section-5.1.2 */
static int 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 0;
}
return 1;
}
static int ext_ec_point_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
uint16_t min_version, max_version;
if (!ssl_get_version_range(hs->ssl, &min_version, &max_version)) {
return 0;
}
/* The point format extension is unneccessary in TLS 1.3. */
if (min_version >= TLS1_3_VERSION) {
return 1;
}
return ext_ec_point_add_extension(hs, out);
}
static int ext_ec_point_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return 1;
}
if (ssl3_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return 0;
}
CBS ec_point_format_list;
if (!CBS_get_u8_length_prefixed(contents, &ec_point_format_list) ||
CBS_len(contents) != 0) {
return 0;
}
/* 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 0;
}
return 1;
}
static int ext_ec_point_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
CBS *contents) {
if (ssl3_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
return 1;
}
return ext_ec_point_parse_serverhello(hs, out_alert, contents);
}
static int ext_ec_point_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
return 1;
}
const uint32_t alg_k = ssl->s3->tmp.new_cipher->algorithm_mkey;
const uint32_t alg_a = ssl->s3->tmp.new_cipher->algorithm_auth;
const int using_ecc = (alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA);
if (!using_ecc) {
return 1;
}
return ext_ec_point_add_extension(hs, out);
}
/* Pre Shared Key
*
* https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.6 */
static size_t ext_pre_shared_key_clienthello_length(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
uint16_t session_version;
if (max_version < TLS1_3_VERSION || ssl->session == NULL ||
!ssl->method->version_from_wire(&session_version,
ssl->session->ssl_version) ||
session_version < TLS1_3_VERSION) {
return 0;
}
const EVP_MD *digest =
ssl_get_handshake_digest(ssl->session->cipher->algorithm_prf);
size_t binder_len = EVP_MD_size(digest);
return 15 + ssl->session->tlsext_ticklen + binder_len;
}
static int ext_pre_shared_key_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
uint16_t session_version;
if (max_version < TLS1_3_VERSION || ssl->session == NULL ||
!ssl->method->version_from_wire(&session_version,
ssl->session->ssl_version) ||
session_version < TLS1_3_VERSION) {
return 1;
}
struct 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};
const EVP_MD *digest =
ssl_get_handshake_digest(ssl->session->cipher->algorithm_prf);
size_t binder_len = EVP_MD_size(digest);
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->tlsext_tick,
ssl->session->tlsext_ticklen) ||
!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 0;
}
hs->needs_psk_binder = 1;
return CBB_flush(out);
}
int 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 0;
}
/* 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 0;
}
return 1;
}
int ssl_ext_pre_shared_key_parse_clienthello(SSL_HANDSHAKE *hs,
SSL_SESSION **out_session,
CBS *out_binders,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
/* We only process the first PSK identity since we don't support pure PSK. */
uint32_t obfuscated_ticket_age;
CBS identities, ticket, binders;
if (!CBS_get_u16_length_prefixed(contents, &identities) ||
!CBS_get_u16_length_prefixed(&identities, &ticket) ||
!CBS_get_u32(&identities, &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 0;
}
*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 0;
}
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 0;
}
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 0;
}
/* TODO(svaldez): Check that the ticket_age is valid when attempting to use
* the PSK for 0-RTT. http://crbug.com/boringssl/113 */
/* TLS 1.3 session tickets are renewed separately as part of the
* NewSessionTicket. */
int unused_renew;
if (!tls_process_ticket(ssl, out_session, &unused_renew, CBS_data(&ticket),
CBS_len(&ticket), NULL, 0)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
return 1;
}
int ssl_ext_pre_shared_key_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
if (!hs->ssl->s3->session_reused) {
return 1;
}
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 0;
}
return 1;
}
/* Pre-Shared Key Exchange Modes
*
* https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.7 */
static int ext_psk_key_exchange_modes_add_clienthello(SSL_HANDSHAKE *hs,
CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
if (max_version < TLS1_3_VERSION) {
return 1;
}
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 0;
}
return CBB_flush(out);
}
static int ext_psk_key_exchange_modes_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return 1;
}
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 0;
}
/* 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 1;
}
/* Early Data Indication
*
* https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.8 */
static int ext_early_data_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
/* TODO(svaldez): Support 0RTT. */
return 1;
}
static int ext_early_data_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert, CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL) {
return 1;
}
if (CBS_len(contents) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
/* Since we don't currently accept 0-RTT, we have to skip past any early data
* the client might have sent. */
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
ssl->s3->skip_early_data = 1;
}
return 1;
}
/* Key Share
*
* https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.5 */
static int ext_key_share_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
if (max_version < TLS1_3_VERSION) {
return 1;
}
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 0;
}
uint16_t group_id = hs->retry_group;
if (hs->received_hello_retry_request) {
/* We received a HelloRetryRequest without a new curve, so there is no new
* share to append. Leave |ecdh_ctx| as-is. */
if (group_id == 0 &&
!CBB_add_bytes(&kse_bytes, hs->key_share_bytes,
hs->key_share_bytes_len)) {
return 0;
}
OPENSSL_free(hs->key_share_bytes);
hs->key_share_bytes = NULL;
hs->key_share_bytes_len = 0;
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(ssl, ssl_grease_group)) ||
!CBB_add_u16(&kse_bytes, 1 /* length */) ||
!CBB_add_u8(&kse_bytes, 0 /* one byte key share */))) {
return 0;
}
/* Predict the most preferred group. */
const uint16_t *groups;
size_t groups_len;
tls1_get_grouplist(ssl, &groups, &groups_len);
if (groups_len == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_GROUPS_SPECIFIED);
return 0;
}
group_id = groups[0];
}
CBB key_exchange;
if (!CBB_add_u16(&kse_bytes, group_id) ||
!CBB_add_u16_length_prefixed(&kse_bytes, &key_exchange) ||
!SSL_ECDH_CTX_init(&hs->ecdh_ctx, group_id) ||
!SSL_ECDH_CTX_offer(&hs->ecdh_ctx, &key_exchange) ||
!CBB_flush(&kse_bytes)) {
return 0;
}
if (!hs->received_hello_retry_request) {
/* Save the contents of the extension to repeat it in the second
* ClientHello. */
hs->key_share_bytes_len = CBB_len(&kse_bytes);
hs->key_share_bytes = BUF_memdup(CBB_data(&kse_bytes), CBB_len(&kse_bytes));
if (hs->key_share_bytes == NULL) {
return 0;
}
}
return CBB_flush(out);
}
int ssl_ext_key_share_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t **out_secret,
size_t *out_secret_len,
uint8_t *out_alert, CBS *contents) {
SSL *const ssl = hs->ssl;
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) {
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
if (SSL_ECDH_CTX_get_id(&hs->ecdh_ctx) != group_id) {
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
return 0;
}
if (!SSL_ECDH_CTX_finish(&hs->ecdh_ctx, out_secret, out_secret_len, out_alert,
CBS_data(&peer_key), CBS_len(&peer_key))) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
ssl->s3->new_session->group_id = group_id;
SSL_ECDH_CTX_cleanup(&hs->ecdh_ctx);
return 1;
}
int ssl_ext_key_share_parse_clienthello(SSL_HANDSHAKE *hs, int *out_found,
uint8_t **out_secret,
size_t *out_secret_len,
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 0;
}
if (!CBS_get_u16_length_prefixed(contents, &key_shares) ||
CBS_len(contents) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return 0;
}
/* Find the corresponding key share. */
int found = 0;
CBS peer_key;
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)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return 0;
}
if (id == group_id) {
if (found) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_KEY_SHARE);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
found = 1;
peer_key = peer_key_tmp;
/* Continue parsing the structure to keep peers honest. */
}
}
if (!found) {
*out_found = 0;
*out_secret = NULL;
*out_secret_len = 0;
return 1;
}
/* Compute the DH secret. */
uint8_t *secret = NULL;
size_t secret_len;
SSL_ECDH_CTX group;
OPENSSL_memset(&group, 0, sizeof(SSL_ECDH_CTX));
CBB public_key;
if (!CBB_init(&public_key, 32) ||
!SSL_ECDH_CTX_init(&group, group_id) ||
!SSL_ECDH_CTX_accept(&group, &public_key, &secret, &secret_len, out_alert,
CBS_data(&peer_key), CBS_len(&peer_key)) ||
!CBB_finish(&public_key, &hs->public_key, &hs->public_key_len)) {
OPENSSL_free(secret);
SSL_ECDH_CTX_cleanup(&group);
CBB_cleanup(&public_key);
*out_alert = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
SSL_ECDH_CTX_cleanup(&group);
*out_secret = secret;
*out_secret_len = secret_len;
*out_found = 1;
return 1;
}
int ssl_ext_key_share_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
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->public_key, hs->public_key_len) ||
!CBB_flush(out)) {
return 0;
}
OPENSSL_free(hs->public_key);
hs->public_key = NULL;
hs->public_key_len = 0;
ssl->s3->new_session->group_id = group_id;
return 1;
}
/* Supported Versions
*
* https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.1 */
static int ext_supported_versions_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
if (max_version <= TLS1_2_VERSION) {
return 1;
}
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 0;
}
/* Add a fake version. See draft-davidben-tls-grease-01. */
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&versions, ssl_get_grease_value(ssl, ssl_grease_version))) {
return 0;
}
for (uint16_t version = max_version; version >= min_version; version--) {
if (!CBB_add_u16(&versions, ssl->method->version_to_wire(version))) {
return 0;
}
}
if (!CBB_flush(out)) {
return 0;
}
return 1;
}
/* Cookie
*
* https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.2 */
static int ext_cookie_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
if (hs->cookie == NULL) {
return 1;
}
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, hs->cookie_len) ||
!CBB_flush(out)) {
return 0;
}
/* The cookie is no longer needed in memory. */
OPENSSL_free(hs->cookie);
hs->cookie = NULL;
hs->cookie_len = 0;
return 1;
}
/* Short record headers
*
* This is a non-standard extension which negotiates
* https://github.com/tlswg/tls13-spec/pull/762 for experimenting. */
static int ext_short_header_add_clienthello(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint16_t min_version, max_version;
if (!ssl_get_version_range(ssl, &min_version, &max_version)) {
return 0;
}
if (max_version < TLS1_3_VERSION ||
!ssl->ctx->short_header_enabled) {
return 1;
}
return CBB_add_u16(out, TLSEXT_TYPE_short_header) &&
CBB_add_u16(out, 0 /* empty extension */);
}
static int ext_short_header_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
SSL *const ssl = hs->ssl;
if (contents == NULL ||
!ssl->ctx->short_header_enabled ||
ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
return 1;
}
if (CBS_len(contents) != 0) {
return 0;
}
ssl->s3->short_header = 1;
return 1;
}
/* Negotiated Groups
*
* https://tools.ietf.org/html/rfc4492#section-5.1.2
* https://tools.ietf.org/html/draft-ietf-tls-tls13-16#section-4.2.4 */
static int 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 0;
}
/* Add a fake group. See draft-davidben-tls-grease-01. */
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&groups_bytes,
ssl_get_grease_value(ssl, ssl_grease_group))) {
return 0;
}
const uint16_t *groups;
size_t groups_len;
tls1_get_grouplist(ssl, &groups, &groups_len);
for (size_t i = 0; i < groups_len; i++) {
if (!CBB_add_u16(&groups_bytes, groups[i])) {
return 0;
}
}
return CBB_flush(out);
}
static int 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 1;
}
static int ext_supported_groups_parse_clienthello(SSL_HANDSHAKE *hs,
uint8_t *out_alert,
CBS *contents) {
if (contents == NULL) {
return 1;
}
CBS supported_group_list;
if (!CBS_get_u16_length_prefixed(contents, &supported_group_list) ||
CBS_len(&supported_group_list) == 0 ||
(CBS_len(&supported_group_list) & 1) != 0 ||
CBS_len(contents) != 0) {
return 0;
}
hs->peer_supported_group_list =
OPENSSL_malloc(CBS_len(&supported_group_list));
if (hs->peer_supported_group_list == NULL) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
const size_t num_groups = CBS_len(&supported_group_list) / 2;
for (size_t i = 0; i < num_groups; i++) {
if (!CBS_get_u16(&supported_group_list,
&hs->peer_supported_group_list[i])) {
goto err;
}
}
assert(CBS_len(&supported_group_list) == 0);
hs->peer_supported_group_list_len = num_groups;
return 1;
err:
OPENSSL_free(hs->peer_supported_group_list);
hs->peer_supported_group_list = NULL;
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
static int ext_supported_groups_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
/* Servers don't echo this extension. */
return 1;
}
/* kExtensions contains all the supported extensions. */
static const struct tls_extension kExtensions[] = {
{
TLSEXT_TYPE_renegotiate,
NULL,
ext_ri_add_clienthello,
ext_ri_parse_serverhello,
ext_ri_parse_clienthello,
ext_ri_add_serverhello,
},
{
TLSEXT_TYPE_server_name,
NULL,
ext_sni_add_clienthello,
ext_sni_parse_serverhello,
ext_sni_parse_clienthello,
ext_sni_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_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_signature_algorithms,
NULL,
ext_sigalgs_add_clienthello,
forbid_parse_serverhello,
ext_sigalgs_parse_clienthello,
dont_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_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_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_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_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_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,
forbid_parse_serverhello,
ext_early_data_parse_clienthello,
dont_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_short_header,
NULL,
ext_short_header_add_clienthello,
forbid_parse_serverhello,
ext_short_header_parse_clienthello,
dont_add_serverhello,
},
/* 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. */
{
TLSEXT_TYPE_supported_groups,
NULL,
ext_supported_groups_add_clienthello,
ext_supported_groups_parse_serverhello,
ext_supported_groups_parse_clienthello,
ext_supported_groups_add_serverhello,
},
};
#define kNumExtensions (sizeof(kExtensions) / sizeof(struct tls_extension))
OPENSSL_COMPILE_ASSERT(kNumExtensions <=
sizeof(((SSL_HANDSHAKE *)NULL)->extensions.sent) * 8,
too_many_extensions_for_sent_bitset);
OPENSSL_COMPILE_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;
}
int SSL_extension_supported(unsigned extension_value) {
uint32_t index;
return extension_value == TLSEXT_TYPE_padding ||
tls_extension_find(&index, extension_value) != NULL;
}
int ssl_add_clienthello_tlsext(SSL_HANDSHAKE *hs, CBB *out, size_t header_len) {
SSL *const ssl = hs->ssl;
/* Don't add extensions for SSLv3 unless doing secure renegotiation. */
if (hs->client_version == SSL3_VERSION &&
!ssl->s3->send_connection_binding) {
return 1;
}
CBB extensions;
if (!CBB_add_u16_length_prefixed(out, &extensions)) {
goto err;
}
hs->extensions.sent = 0;
hs->custom_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(ssl, ssl_grease_extension1);
if (!CBB_add_u16(&extensions, grease_ext1) ||
!CBB_add_u16(&extensions, 0 /* zero length */)) {
goto err;
}
}
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);
goto err;
}
if (CBB_len(&extensions) != len_before) {
hs->extensions.sent |= (1u << i);
}
}
if (!custom_ext_add_clienthello(hs, &extensions)) {
goto err;
}
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(ssl, 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 */)) {
goto err;
}
}
if (!SSL_is_dtls(ssl)) {
size_t psk_extension_len = ext_pre_shared_key_clienthello_length(hs);
header_len += 2 + CBB_len(&extensions) + psk_extension_len;
if (header_len > 0xff && header_len < 0x200) {
/* 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. */
size_t 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;
}
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)) {
goto err;
}
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)) {
goto err;
}
/* Discard empty extensions blocks. */
if (CBB_len(&extensions) == 0) {
CBB_discard_child(out);
}
return CBB_flush(out);
err:
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return 0;
}
int 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;
}
}
if (!custom_ext_add_serverhello(hs, &extensions)) {
goto err;
}
/* Discard empty extensions blocks before TLS 1.3. */
if (ssl3_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 0;
}
static int ssl_scan_clienthello_tlsext(SSL_HANDSHAKE *hs,
const SSL_CLIENT_HELLO *client_hello,
int *out_alert) {
SSL *const ssl = hs->ssl;
for (size_t i = 0; i < kNumExtensions; i++) {
if (kExtensions[i].init != NULL) {
kExtensions[i].init(hs);
}
}
hs->extensions.received = 0;
hs->custom_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 0;
}
/* RFC 5746 made the existence of extensions in SSL 3.0 somewhat
* ambiguous. Ignore all but the renegotiation_info extension. */
if (ssl->version == SSL3_VERSION && type != TLSEXT_TYPE_renegotiate) {
continue;
}
unsigned ext_index;
const struct tls_extension *const ext =
tls_extension_find(&ext_index, type);
if (ext == NULL) {
if (!custom_ext_parse_clienthello(hs, out_alert, type, &extension)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
return 0;
}
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 0;
}
}
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 0;
}
}
return 1;
}
int ssl_parse_clienthello_tlsext(SSL_HANDSHAKE *hs,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
int alert = -1;
if (ssl_scan_clienthello_tlsext(hs, client_hello, &alert) <= 0) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return 0;
}
if (ssl_check_clienthello_tlsext(hs) <= 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_TLSEXT);
return 0;
}
return 1;
}
OPENSSL_COMPILE_ASSERT(kNumExtensions <= sizeof(uint32_t) * 8, too_many_bits);
static int 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 && ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
return 1;
}
/* 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 0;
}
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 0;
}
unsigned ext_index;
const struct tls_extension *const ext =
tls_extension_find(&ext_index, type);
if (ext == NULL) {
if (!custom_ext_parse_serverhello(hs, out_alert, type, &extension)) {
return 0;
}
continue;
}
if (!(hs->extensions.sent & (1u << ext_index)) &&
type != TLSEXT_TYPE_renegotiate) {
/* If the extension was never sent then it is illegal, except for the
* renegotiation extension which, in SSL 3.0, is signaled via SCSV. */
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
ERR_add_error_dataf("extension :%u", (unsigned)type);
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return 0;
}
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 0;
}
}
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 0;
}
}
}
return 1;
}
static int ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int ret = SSL_TLSEXT_ERR_NOACK;
int al = SSL_AD_UNRECOGNIZED_NAME;
if (ssl->ctx->tlsext_servername_callback != 0) {
ret = ssl->ctx->tlsext_servername_callback(ssl, &al,
ssl->ctx->tlsext_servername_arg);
} else if (ssl->initial_ctx->tlsext_servername_callback != 0) {
ret = ssl->initial_ctx->tlsext_servername_callback(
ssl, &al, ssl->initial_ctx->tlsext_servername_arg);
}
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
ssl3_send_alert(ssl, SSL3_AL_FATAL, al);
return -1;
case SSL_TLSEXT_ERR_ALERT_WARNING:
ssl3_send_alert(ssl, SSL3_AL_WARNING, al);
return 1;
case SSL_TLSEXT_ERR_NOACK:
hs->should_ack_sni = 0;
return 1;
default:
return 1;
}
}
static int ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int ret = SSL_TLSEXT_ERR_OK;
int al = SSL_AD_UNRECOGNIZED_NAME;
if (ssl->ctx->tlsext_servername_callback != 0) {
ret = ssl->ctx->tlsext_servername_callback(ssl, &al,
ssl->ctx->tlsext_servername_arg);
} else if (ssl->initial_ctx->tlsext_servername_callback != 0) {
ret = ssl->initial_ctx->tlsext_servername_callback(
ssl, &al, ssl->initial_ctx->tlsext_servername_arg);
}
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
ssl3_send_alert(ssl, SSL3_AL_FATAL, al);
return -1;
case SSL_TLSEXT_ERR_ALERT_WARNING:
ssl3_send_alert(ssl, SSL3_AL_WARNING, al);
return 1;
default:
return 1;
}
}
int ssl_parse_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs) {
SSL *const ssl = hs->ssl;
int alert = -1;
if (ssl_scan_serverhello_tlsext(hs, cbs, &alert) <= 0) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return 0;
}
if (ssl_check_serverhello_tlsext(hs) <= 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_SERVERHELLO_TLSEXT);
return 0;
}
return 1;
}
int tls_process_ticket(SSL *ssl, SSL_SESSION **out_session,
int *out_renew_ticket, const uint8_t *ticket,
size_t ticket_len, const uint8_t *session_id,
size_t session_id_len) {
int ret = 1; /* Most errors are non-fatal. */
SSL_CTX *ssl_ctx = ssl->initial_ctx;
uint8_t *plaintext = NULL;
HMAC_CTX hmac_ctx;
HMAC_CTX_init(&hmac_ctx);
EVP_CIPHER_CTX cipher_ctx;
EVP_CIPHER_CTX_init(&cipher_ctx);
*out_renew_ticket = 0;
*out_session = NULL;
if (SSL_get_options(ssl) & SSL_OP_NO_TICKET) {
goto done;
}
if (session_id_len > SSL_MAX_SSL_SESSION_ID_LENGTH) {
goto done;
}
/* Ensure there is room for the key name and the largest IV
* |tlsext_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_len < SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH) {
goto done;
}
const uint8_t *iv = ticket + SSL_TICKET_KEY_NAME_LEN;
if (ssl_ctx->tlsext_ticket_key_cb != NULL) {
int cb_ret = ssl_ctx->tlsext_ticket_key_cb(
ssl, (uint8_t *)ticket /* name */, (uint8_t *)iv, &cipher_ctx,
&hmac_ctx, 0 /* decrypt */);
if (cb_ret < 0) {
ret = 0;
goto done;
}
if (cb_ret == 0) {
goto done;
}
if (cb_ret == 2) {
*out_renew_ticket = 1;
}
} else {
/* Check the key name matches. */
if (OPENSSL_memcmp(ticket, ssl_ctx->tlsext_tick_key_name,
SSL_TICKET_KEY_NAME_LEN) != 0) {
goto done;
}
if (!HMAC_Init_ex(&hmac_ctx, ssl_ctx->tlsext_tick_hmac_key,
sizeof(ssl_ctx->tlsext_tick_hmac_key), tlsext_tick_md(),
NULL) ||
!EVP_DecryptInit_ex(&cipher_ctx, EVP_aes_128_cbc(), NULL,
ssl_ctx->tlsext_tick_aes_key, iv)) {
ret = 0;
goto done;
}
}
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_len < SSL_TICKET_KEY_NAME_LEN + iv_len + 1 + mac_len) {
/* The ticket must be large enough for key name, IV, data, and MAC. */
goto done;
}
HMAC_Update(&hmac_ctx, ticket, ticket_len - mac_len);
HMAC_Final(&hmac_ctx, mac, NULL);
int mac_ok =
CRYPTO_memcmp(mac, ticket + (ticket_len - mac_len), mac_len) == 0;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
mac_ok = 1;
#endif
if (!mac_ok) {
goto done;
}
/* Decrypt the session data. */
const uint8_t *ciphertext = ticket + SSL_TICKET_KEY_NAME_LEN + iv_len;
size_t ciphertext_len = ticket_len - SSL_TICKET_KEY_NAME_LEN - iv_len -
mac_len;
plaintext = OPENSSL_malloc(ciphertext_len);
if (plaintext == NULL) {
ret = 0;
goto done;
}
size_t plaintext_len;
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
OPENSSL_memcpy(plaintext, ciphertext, ciphertext_len);
plaintext_len = ciphertext_len;
#else
if (ciphertext_len >= INT_MAX) {
goto done;
}
int len1, len2;
if (!EVP_DecryptUpdate(&cipher_ctx, plaintext, &len1, ciphertext,
(int)ciphertext_len) ||
!EVP_DecryptFinal_ex(&cipher_ctx, plaintext + len1, &len2)) {
ERR_clear_error(); /* Don't leave an error on the queue. */
goto done;
}
plaintext_len = (size_t)(len1 + len2);
#endif
/* Decode the session. */
SSL_SESSION *session = SSL_SESSION_from_bytes(plaintext, plaintext_len);
if (session == NULL) {
ERR_clear_error(); /* Don't leave an error on the queue. */
goto done;
}
/* Copy the client's session ID into the new session, to denote the ticket has
* been accepted. */
OPENSSL_memcpy(session->session_id, session_id, session_id_len);
session->session_id_length = session_id_len;
*out_session = session;
done:
OPENSSL_free(plaintext);
HMAC_CTX_cleanup(&hmac_ctx);
EVP_CIPHER_CTX_cleanup(&cipher_ctx);
return ret;
}
int tls1_parse_peer_sigalgs(SSL_HANDSHAKE *hs, const CBS *in_sigalgs) {
/* Extension ignored for inappropriate versions */
if (ssl3_protocol_version(hs->ssl) < TLS1_2_VERSION) {
return 1;
}
OPENSSL_free(hs->peer_sigalgs);
hs->peer_sigalgs = NULL;
hs->num_peer_sigalgs = 0;
size_t num_sigalgs = CBS_len(in_sigalgs);
if (num_sigalgs % 2 != 0) {
return 0;
}
num_sigalgs /= 2;
/* supported_signature_algorithms in the certificate request is
* allowed to be empty. */
if (num_sigalgs == 0) {
return 1;
}
/* This multiplication doesn't overflow because sizeof(uint16_t) is two
* and we just divided |num_sigalgs| by two. */
hs->peer_sigalgs = OPENSSL_malloc(num_sigalgs * sizeof(uint16_t));
if (hs->peer_sigalgs == NULL) {
return 0;
}
hs->num_peer_sigalgs = num_sigalgs;
CBS sigalgs;
CBS_init(&sigalgs, CBS_data(in_sigalgs), CBS_len(in_sigalgs));
for (size_t i = 0; i < num_sigalgs; i++) {
if (!CBS_get_u16(&sigalgs, &hs->peer_sigalgs[i])) {
return 0;
}
}
return 1;
}
int tls1_choose_signature_algorithm(SSL_HANDSHAKE *hs, uint16_t *out) {
SSL *const ssl = hs->ssl;
CERT *cert = ssl->cert;
/* Before TLS 1.2, the signature algorithm isn't negotiated as part of the
* handshake. It is fixed at MD5-SHA1 for RSA and SHA1 for ECDSA. */
if (ssl3_protocol_version(ssl) < TLS1_2_VERSION) {
int type = ssl_private_key_type(ssl);
if (type == NID_rsaEncryption) {
*out = SSL_SIGN_RSA_PKCS1_MD5_SHA1;
return 1;
}
if (ssl_is_ecdsa_key_type(type)) {
*out = SSL_SIGN_ECDSA_SHA1;
return 1;
}
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
return 0;
}
const uint16_t *sigalgs = cert->sigalgs;
size_t num_sigalgs = cert->num_sigalgs;
if (sigalgs == NULL) {
sigalgs = kSignSignatureAlgorithms;
num_sigalgs = OPENSSL_ARRAY_SIZE(kSignSignatureAlgorithms);
}
const uint16_t *peer_sigalgs = hs->peer_sigalgs;
size_t num_peer_sigalgs = hs->num_peer_sigalgs;
if (num_peer_sigalgs == 0 && ssl3_protocol_version(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;
num_peer_sigalgs = OPENSSL_ARRAY_SIZE(kDefaultPeerAlgorithms);
}
for (size_t i = 0; i < num_sigalgs; i++) {
uint16_t sigalg = sigalgs[i];
/* 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(ssl, sigalgs[i])) {
continue;
}
for (size_t j = 0; j < num_peer_sigalgs; j++) {
if (sigalg == peer_sigalgs[j]) {
*out = sigalg;
return 1;
}
}
}
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
return 0;
}
int tls1_verify_channel_id(SSL *ssl) {
int ret = 0;
uint16_t extension_type;
CBS extension, channel_id;
/* A Channel ID handshake message is structured to contain multiple
* extensions, but the only one that can be present is Channel ID. */
CBS_init(&channel_id, ssl->init_msg, ssl->init_num);
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);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return 0;
}
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 0;
}
EC_KEY *key = NULL;
EC_POINT *point = NULL;
BIGNUM x, y;
ECDSA_SIG sig;
BN_init(&x);
BN_init(&y);
sig.r = BN_new();
sig.s = BN_new();
if (sig.r == NULL || sig.s == NULL) {
goto err;
}
const uint8_t *p = CBS_data(&extension);
if (BN_bin2bn(p + 0, 32, &x) == NULL ||
BN_bin2bn(p + 32, 32, &y) == NULL ||
BN_bin2bn(p + 64, 32, sig.r) == NULL ||
BN_bin2bn(p + 96, 32, sig.s) == NULL) {
goto err;
}
point = EC_POINT_new(p256);
if (point == NULL ||
!EC_POINT_set_affine_coordinates_GFp(p256, point, &x, &y, NULL)) {
goto err;
}
key = EC_KEY_new();
if (key == NULL ||
!EC_KEY_set_group(key, p256) ||
!EC_KEY_set_public_key(key, point)) {
goto err;
}
uint8_t digest[EVP_MAX_MD_SIZE];
size_t digest_len;
if (!tls1_channel_id_hash(ssl, digest, &digest_len)) {
goto err;
}
int sig_ok = ECDSA_do_verify(digest, digest_len, &sig, key);
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
sig_ok = 1;
#endif
if (!sig_ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_SIGNATURE_INVALID);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
ssl->s3->tlsext_channel_id_valid = 0;
goto err;
}
OPENSSL_memcpy(ssl->s3->tlsext_channel_id, p, 64);
ret = 1;
err:
BN_free(&x);
BN_free(&y);
BN_free(sig.r);
BN_free(sig.s);
EC_KEY_free(key);
EC_POINT_free(point);
EC_GROUP_free(p256);
return ret;
}
int tls1_write_channel_id(SSL *ssl, CBB *cbb) {
uint8_t digest[EVP_MAX_MD_SIZE];
size_t digest_len;
if (!tls1_channel_id_hash(ssl, digest, &digest_len)) {
return 0;
}
EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(ssl->tlsext_channel_id_private);
if (ec_key == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return 0;
}
int ret = 0;
BIGNUM *x = BN_new();
BIGNUM *y = BN_new();
ECDSA_SIG *sig = NULL;
if (x == NULL || y == NULL ||
!EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(ec_key),
EC_KEY_get0_public_key(ec_key),
x, y, NULL)) {
goto err;
}
sig = ECDSA_do_sign(digest, digest_len, ec_key);
if (sig == NULL) {
goto err;
}
CBB child;
if (!CBB_add_u16(cbb, TLSEXT_TYPE_channel_id) ||
!CBB_add_u16_length_prefixed(cbb, &child) ||
!BN_bn2cbb_padded(&child, 32, x) ||
!BN_bn2cbb_padded(&child, 32, y) ||
!BN_bn2cbb_padded(&child, 32, sig->r) ||
!BN_bn2cbb_padded(&child, 32, sig->s) ||
!CBB_flush(cbb)) {
goto err;
}
ret = 1;
err:
BN_free(x);
BN_free(y);
ECDSA_SIG_free(sig);
return ret;
}
int tls1_channel_id_hash(SSL *ssl, uint8_t *out, size_t *out_len) {
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
uint8_t *msg;
size_t msg_len;
if (!tls13_get_cert_verify_signature_input(ssl, &msg, &msg_len,
ssl_cert_verify_channel_id)) {
return 0;
}
SHA256(msg, msg_len, out);
*out_len = SHA256_DIGEST_LENGTH;
OPENSSL_free(msg);
return 1;
}
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 0;
}
SHA256_Update(&ctx, ssl->session->original_handshake_hash,
ssl->session->original_handshake_hash_len);
}
uint8_t handshake_hash[EVP_MAX_MD_SIZE];
int handshake_hash_len = tls1_handshake_digest(ssl, handshake_hash,
sizeof(handshake_hash));
if (handshake_hash_len < 0) {
return 0;
}
SHA256_Update(&ctx, handshake_hash, (size_t)handshake_hash_len);
SHA256_Final(out, &ctx);
*out_len = SHA256_DIGEST_LENGTH;
return 1;
}
/* tls1_record_handshake_hashes_for_channel_id records the current handshake
* hashes in |ssl->s3->new_session| so that Channel ID resumptions can sign that
* data. */
int tls1_record_handshake_hashes_for_channel_id(SSL *ssl) {
int digest_len;
/* 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 -1;
}
digest_len =
tls1_handshake_digest(
ssl, ssl->s3->new_session->original_handshake_hash,
sizeof(ssl->s3->new_session->original_handshake_hash));
if (digest_len < 0) {
return -1;
}
assert(sizeof(ssl->s3->new_session->original_handshake_hash) < 256);
ssl->s3->new_session->original_handshake_hash_len = (uint8_t)digest_len;
return 1;
}
int ssl_do_channel_id_callback(SSL *ssl) {
if (ssl->tlsext_channel_id_private != NULL ||
ssl->ctx->channel_id_cb == NULL) {
return 1;
}
EVP_PKEY *key = NULL;
ssl->ctx->channel_id_cb(ssl, &key);
if (key == NULL) {
/* The caller should try again later. */
return 1;
}
int ret = SSL_set1_tls_channel_id(ssl, key);
EVP_PKEY_free(key);
return ret;
}
int 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 0;
}
while (CBS_len(&sct_list) > 0) {
CBS sct;
if (!CBS_get_u16_length_prefixed(&sct_list, &sct) ||
CBS_len(&sct) == 0) {
return 0;
}
}
return 1;
}