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openssl/ssl/statem/extensions_cust.c

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/*
* Copyright 2014-2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
/* Custom extension utility functions */
#include <openssl/ct.h>
#include "../ssl_local.h"
#include "internal/cryptlib.h"
#include "statem_local.h"
typedef struct {
void *add_arg;
custom_ext_add_cb add_cb;
custom_ext_free_cb free_cb;
} custom_ext_add_cb_wrap;
typedef struct {
void *parse_arg;
custom_ext_parse_cb parse_cb;
} custom_ext_parse_cb_wrap;
/*
* Provide thin wrapper callbacks which convert new style arguments to old style
*/
static int custom_ext_add_old_cb_wrap(SSL *s, unsigned int ext_type,
unsigned int context,
const unsigned char **out,
size_t *outlen, X509 *x, size_t chainidx,
int *al, void *add_arg)
{
custom_ext_add_cb_wrap *add_cb_wrap = (custom_ext_add_cb_wrap *)add_arg;
if (add_cb_wrap->add_cb == NULL)
return 1;
return add_cb_wrap->add_cb(s, ext_type, out, outlen, al,
add_cb_wrap->add_arg);
}
static void custom_ext_free_old_cb_wrap(SSL *s, unsigned int ext_type,
unsigned int context,
const unsigned char *out, void *add_arg)
{
custom_ext_add_cb_wrap *add_cb_wrap = (custom_ext_add_cb_wrap *)add_arg;
if (add_cb_wrap->free_cb == NULL)
return;
add_cb_wrap->free_cb(s, ext_type, out, add_cb_wrap->add_arg);
}
static int custom_ext_parse_old_cb_wrap(SSL *s, unsigned int ext_type,
unsigned int context,
const unsigned char *in,
size_t inlen, X509 *x, size_t chainidx,
int *al, void *parse_arg)
{
custom_ext_parse_cb_wrap *parse_cb_wrap =
(custom_ext_parse_cb_wrap *)parse_arg;
if (parse_cb_wrap->parse_cb == NULL)
return 1;
return parse_cb_wrap->parse_cb(s, ext_type, in, inlen, al,
parse_cb_wrap->parse_arg);
}
/*
* Find a custom extension from the list. The |role| param is there to
* support the legacy API where custom extensions for client and server could
* be set independently on the same SSL_CTX. It is set to ENDPOINT_SERVER if we
* are trying to find a method relevant to the server, ENDPOINT_CLIENT for the
* client, or ENDPOINT_BOTH for either
*/
custom_ext_method *custom_ext_find(const custom_ext_methods *exts,
ENDPOINT role, unsigned int ext_type,
size_t *idx)
{
size_t i;
custom_ext_method *meth = exts->meths;
for (i = 0; i < exts->meths_count; i++, meth++) {
if (ext_type == meth->ext_type
&& (role == ENDPOINT_BOTH || role == meth->role
|| meth->role == ENDPOINT_BOTH)) {
if (idx != NULL)
*idx = i;
return meth;
}
}
return NULL;
}
/*
* Initialise custom extensions flags to indicate neither sent nor received.
*/
void custom_ext_init(custom_ext_methods *exts)
{
size_t i;
custom_ext_method *meth = exts->meths;
for (i = 0; i < exts->meths_count; i++, meth++)
meth->ext_flags = 0;
}
/* Pass received custom extension data to the application for parsing. */
int custom_ext_parse(SSL *s, unsigned int context, unsigned int ext_type,
const unsigned char *ext_data, size_t ext_size, X509 *x,
size_t chainidx)
{
int al;
custom_ext_methods *exts = &s->cert->custext;
custom_ext_method *meth;
ENDPOINT role = ENDPOINT_BOTH;
if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0)
role = s->server ? ENDPOINT_SERVER : ENDPOINT_CLIENT;
meth = custom_ext_find(exts, role, ext_type, NULL);
/* If not found return success */
if (!meth)
return 1;
/* Check if extension is defined for our protocol. If not, skip */
if (!extension_is_relevant(s, meth->context, context))
return 1;
if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_3_SERVER_HELLO
| SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS)) != 0) {
/*
* If it's ServerHello or EncryptedExtensions we can't have any
* extensions not sent in ClientHello.
*/
if ((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0) {
SSLfatal(s, TLS1_AD_UNSUPPORTED_EXTENSION, SSL_F_CUSTOM_EXT_PARSE,
SSL_R_BAD_EXTENSION);
return 0;
}
}
/*
* Extensions received in the ClientHello or CertificateRequest are marked
* with the SSL_EXT_FLAG_RECEIVED. This is so we know to add the equivalent
* extensions in the response messages
*/
if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST))
!= 0)
meth->ext_flags |= SSL_EXT_FLAG_RECEIVED;
/* If no parse function set return success */
if (!meth->parse_cb)
return 1;
if (meth->parse_cb(s, ext_type, context, ext_data, ext_size, x, chainidx,
&al, meth->parse_arg) <= 0) {
SSLfatal(s, al, SSL_F_CUSTOM_EXT_PARSE, SSL_R_BAD_EXTENSION);
return 0;
}
return 1;
}
/*
* Request custom extension data from the application and add to the return
* buffer.
*/
int custom_ext_add(SSL *s, int context, WPACKET *pkt, X509 *x, size_t chainidx,
int maxversion)
{
custom_ext_methods *exts = &s->cert->custext;
custom_ext_method *meth;
size_t i;
int al;
for (i = 0; i < exts->meths_count; i++) {
const unsigned char *out = NULL;
size_t outlen = 0;
meth = exts->meths + i;
if (!should_add_extension(s, meth->context, context, maxversion))
continue;
if ((context & (SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_3_SERVER_HELLO
| SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| SSL_EXT_TLS1_3_CERTIFICATE
| SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST)) != 0) {
/* Only send extensions present in ClientHello/CertificateRequest */
if (!(meth->ext_flags & SSL_EXT_FLAG_RECEIVED))
continue;
}
/*
* We skip it if the callback is absent - except for a ClientHello where
* we add an empty extension.
*/
if ((context & SSL_EXT_CLIENT_HELLO) == 0 && meth->add_cb == NULL)
continue;
if (meth->add_cb != NULL) {
int cb_retval = meth->add_cb(s, meth->ext_type, context, &out,
&outlen, x, chainidx, &al,
meth->add_arg);
if (cb_retval < 0) {
SSLfatal(s, al, SSL_F_CUSTOM_EXT_ADD, SSL_R_CALLBACK_FAILED);
return 0; /* error */
}
if (cb_retval == 0)
continue; /* skip this extension */
}
if (!WPACKET_put_bytes_u16(pkt, meth->ext_type)
|| !WPACKET_start_sub_packet_u16(pkt)
|| (outlen > 0 && !WPACKET_memcpy(pkt, out, outlen))
|| !WPACKET_close(pkt)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_CUSTOM_EXT_ADD,
ERR_R_INTERNAL_ERROR);
return 0;
}
if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
/*
* We can't send duplicates: code logic should prevent this.
*/
if (!ossl_assert((meth->ext_flags & SSL_EXT_FLAG_SENT) == 0)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_CUSTOM_EXT_ADD,
ERR_R_INTERNAL_ERROR);
return 0;
}
/*
* Indicate extension has been sent: this is both a sanity check to
* ensure we don't send duplicate extensions and indicates that it
* is not an error if the extension is present in ServerHello.
*/
meth->ext_flags |= SSL_EXT_FLAG_SENT;
}
if (meth->free_cb != NULL)
meth->free_cb(s, meth->ext_type, context, out, meth->add_arg);
}
return 1;
}
/* Copy the flags from src to dst for any extensions that exist in both */
int custom_exts_copy_flags(custom_ext_methods *dst,
const custom_ext_methods *src)
{
size_t i;
custom_ext_method *methsrc = src->meths;
for (i = 0; i < src->meths_count; i++, methsrc++) {
custom_ext_method *methdst = custom_ext_find(dst, methsrc->role,
methsrc->ext_type, NULL);
if (methdst == NULL)
continue;
methdst->ext_flags = methsrc->ext_flags;
}
return 1;
}
/* Copy table of custom extensions */
int custom_exts_copy(custom_ext_methods *dst, const custom_ext_methods *src)
{
size_t i;
int err = 0;
if (src->meths_count > 0) {
dst->meths =
OPENSSL_memdup(src->meths,
sizeof(*src->meths) * src->meths_count);
if (dst->meths == NULL)
return 0;
dst->meths_count = src->meths_count;
for (i = 0; i < src->meths_count; i++) {
custom_ext_method *methsrc = src->meths + i;
custom_ext_method *methdst = dst->meths + i;
if (methsrc->add_cb != custom_ext_add_old_cb_wrap)
continue;
/*
* We have found an old style API wrapper. We need to copy the
* arguments too.
*/
if (err) {
methdst->add_arg = NULL;
methdst->parse_arg = NULL;
continue;
}
methdst->add_arg = OPENSSL_memdup(methsrc->add_arg,
sizeof(custom_ext_add_cb_wrap));
methdst->parse_arg = OPENSSL_memdup(methsrc->parse_arg,
sizeof(custom_ext_parse_cb_wrap));
if (methdst->add_arg == NULL || methdst->parse_arg == NULL)
err = 1;
}
}
if (err) {
custom_exts_free(dst);
return 0;
}
return 1;
}
void custom_exts_free(custom_ext_methods *exts)
{
size_t i;
custom_ext_method *meth;
for (i = 0, meth = exts->meths; i < exts->meths_count; i++, meth++) {
if (meth->add_cb != custom_ext_add_old_cb_wrap)
continue;
/* Old style API wrapper. Need to free the arguments too */
OPENSSL_free(meth->add_arg);
OPENSSL_free(meth->parse_arg);
}
OPENSSL_free(exts->meths);
}
/* Return true if a client custom extension exists, false otherwise */
int SSL_CTX_has_client_custom_ext(const SSL_CTX *ctx, unsigned int ext_type)
{
return custom_ext_find(&ctx->cert->custext, ENDPOINT_CLIENT, ext_type,
NULL) != NULL;
}
static int add_custom_ext_intern(SSL_CTX *ctx, ENDPOINT role,
unsigned int ext_type,
unsigned int context,
SSL_custom_ext_add_cb_ex add_cb,
SSL_custom_ext_free_cb_ex free_cb,
void *add_arg,
SSL_custom_ext_parse_cb_ex parse_cb,
void *parse_arg)
{
custom_ext_methods *exts = &ctx->cert->custext;
custom_ext_method *meth, *tmp;
/*
* Check application error: if add_cb is not set free_cb will never be
* called.
*/
if (add_cb == NULL && free_cb != NULL)
return 0;
#ifndef OPENSSL_NO_CT
/*
* We don't want applications registering callbacks for SCT extensions
* whilst simultaneously using the built-in SCT validation features, as
* these two things may not play well together.
*/
if (ext_type == TLSEXT_TYPE_signed_certificate_timestamp
&& (context & SSL_EXT_CLIENT_HELLO) != 0
&& SSL_CTX_ct_is_enabled(ctx))
return 0;
#endif
/*
* Don't add if extension supported internally, but make exception
* for extension types that previously were not supported, but now are.
*/
if (SSL_extension_supported(ext_type)
&& ext_type != TLSEXT_TYPE_signed_certificate_timestamp)
return 0;
/* Extension type must fit in 16 bits */
if (ext_type > 0xffff)
return 0;
/* Search for duplicate */
if (custom_ext_find(exts, role, ext_type, NULL))
return 0;
tmp = OPENSSL_realloc(exts->meths,
(exts->meths_count + 1) * sizeof(custom_ext_method));
if (tmp == NULL)
return 0;
exts->meths = tmp;
meth = exts->meths + exts->meths_count;
memset(meth, 0, sizeof(*meth));
meth->role = role;
meth->context = context;
meth->parse_cb = parse_cb;
meth->add_cb = add_cb;
meth->free_cb = free_cb;
meth->ext_type = ext_type;
meth->add_arg = add_arg;
meth->parse_arg = parse_arg;
exts->meths_count++;
return 1;
}
static int add_old_custom_ext(SSL_CTX *ctx, ENDPOINT role,
unsigned int ext_type,
unsigned int context,
custom_ext_add_cb add_cb,
custom_ext_free_cb free_cb,
void *add_arg,
custom_ext_parse_cb parse_cb, void *parse_arg)
{
custom_ext_add_cb_wrap *add_cb_wrap
= OPENSSL_malloc(sizeof(*add_cb_wrap));
custom_ext_parse_cb_wrap *parse_cb_wrap
= OPENSSL_malloc(sizeof(*parse_cb_wrap));
int ret;
if (add_cb_wrap == NULL || parse_cb_wrap == NULL) {
OPENSSL_free(add_cb_wrap);
OPENSSL_free(parse_cb_wrap);
return 0;
}
add_cb_wrap->add_arg = add_arg;
add_cb_wrap->add_cb = add_cb;
add_cb_wrap->free_cb = free_cb;
parse_cb_wrap->parse_arg = parse_arg;
parse_cb_wrap->parse_cb = parse_cb;
ret = add_custom_ext_intern(ctx, role, ext_type,
context,
custom_ext_add_old_cb_wrap,
custom_ext_free_old_cb_wrap,
add_cb_wrap,
custom_ext_parse_old_cb_wrap,
parse_cb_wrap);
if (!ret) {
OPENSSL_free(add_cb_wrap);
OPENSSL_free(parse_cb_wrap);
}
return ret;
}
/* Application level functions to add the old custom extension callbacks */
int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
custom_ext_add_cb add_cb,
custom_ext_free_cb free_cb,
void *add_arg,
custom_ext_parse_cb parse_cb, void *parse_arg)
{
return add_old_custom_ext(ctx, ENDPOINT_CLIENT, ext_type,
SSL_EXT_TLS1_2_AND_BELOW_ONLY
| SSL_EXT_CLIENT_HELLO
| SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_IGNORE_ON_RESUMPTION,
add_cb, free_cb, add_arg, parse_cb, parse_arg);
}
int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
custom_ext_add_cb add_cb,
custom_ext_free_cb free_cb,
void *add_arg,
custom_ext_parse_cb parse_cb, void *parse_arg)
{
return add_old_custom_ext(ctx, ENDPOINT_SERVER, ext_type,
SSL_EXT_TLS1_2_AND_BELOW_ONLY
| SSL_EXT_CLIENT_HELLO
| SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_IGNORE_ON_RESUMPTION,
add_cb, free_cb, add_arg, parse_cb, parse_arg);
}
int SSL_CTX_add_custom_ext(SSL_CTX *ctx, unsigned int ext_type,
unsigned int context,
SSL_custom_ext_add_cb_ex add_cb,
SSL_custom_ext_free_cb_ex free_cb,
void *add_arg,
SSL_custom_ext_parse_cb_ex parse_cb, void *parse_arg)
{
return add_custom_ext_intern(ctx, ENDPOINT_BOTH, ext_type, context, add_cb,
free_cb, add_arg, parse_cb, parse_arg);
}
int SSL_extension_supported(unsigned int ext_type)
{
switch (ext_type) {
/* Internally supported extensions. */
case TLSEXT_TYPE_application_layer_protocol_negotiation:
#ifndef OPENSSL_NO_EC
case TLSEXT_TYPE_ec_point_formats:
case TLSEXT_TYPE_supported_groups:
case TLSEXT_TYPE_key_share:
#endif
#ifndef OPENSSL_NO_NEXTPROTONEG
case TLSEXT_TYPE_next_proto_neg:
#endif
case TLSEXT_TYPE_padding:
case TLSEXT_TYPE_renegotiate:
case TLSEXT_TYPE_max_fragment_length:
case TLSEXT_TYPE_server_name:
case TLSEXT_TYPE_session_ticket:
case TLSEXT_TYPE_signature_algorithms:
#ifndef OPENSSL_NO_SRP
case TLSEXT_TYPE_srp:
#endif
#ifndef OPENSSL_NO_OCSP
case TLSEXT_TYPE_status_request:
#endif
#ifndef OPENSSL_NO_CT
case TLSEXT_TYPE_signed_certificate_timestamp:
#endif
#ifndef OPENSSL_NO_SRTP
case TLSEXT_TYPE_use_srtp:
#endif
case TLSEXT_TYPE_encrypt_then_mac:
case TLSEXT_TYPE_supported_versions:
case TLSEXT_TYPE_extended_master_secret:
case TLSEXT_TYPE_psk_kex_modes:
case TLSEXT_TYPE_cookie:
case TLSEXT_TYPE_early_data:
case TLSEXT_TYPE_certificate_authorities:
case TLSEXT_TYPE_psk:
case TLSEXT_TYPE_post_handshake_auth:
return 1;
default:
return 0;
}
}
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