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boringssl/ssl/custom_extensions.c
David Benjamin f5d2cd0808 Move extensions bitmasks into SSL_HANDSHAKE. 
Change-Id: I3ab30a44b7f90ef1159e022cd17b7f50ffe27a93
Reviewed-on: https://boringssl-review.googlesource.com/11522
Reviewed-by: Adam Langley <agl@google.com>
2016-10-09 16:48:52 +00:00

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/* Copyright (c) 2014, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <openssl/ssl.h>
#include <assert.h>
#include <string.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/stack.h>
#include "internal.h"
void SSL_CUSTOM_EXTENSION_free(SSL_CUSTOM_EXTENSION *custom_extension) {
OPENSSL_free(custom_extension);
}
static const SSL_CUSTOM_EXTENSION *custom_ext_find(
STACK_OF(SSL_CUSTOM_EXTENSION) *stack,
unsigned *out_index, uint16_t value) {
for (size_t i = 0; i < sk_SSL_CUSTOM_EXTENSION_num(stack); i++) {
const SSL_CUSTOM_EXTENSION *ext = sk_SSL_CUSTOM_EXTENSION_value(stack, i);
if (ext->value == value) {
if (out_index != NULL) {
*out_index = i;
}
return ext;
}
}
return NULL;
}
/* default_add_callback is used as the |add_callback| when the user doesn't
* provide one. For servers, it does nothing while, for clients, it causes an
* empty extension to be included. */
static int default_add_callback(SSL *ssl, unsigned extension_value,
const uint8_t **out, size_t *out_len,
int *out_alert_value, void *add_arg) {
if (ssl->server) {
return 0;
}
*out_len = 0;
return 1;
}
static int custom_ext_add_hello(SSL *ssl, CBB *extensions) {
STACK_OF(SSL_CUSTOM_EXTENSION) *stack = ssl->ctx->client_custom_extensions;
if (ssl->server) {
stack = ssl->ctx->server_custom_extensions;
}
if (stack == NULL) {
return 1;
}
for (size_t i = 0; i < sk_SSL_CUSTOM_EXTENSION_num(stack); i++) {
const SSL_CUSTOM_EXTENSION *ext = sk_SSL_CUSTOM_EXTENSION_value(stack, i);
if (ssl->server &&
!(ssl->s3->hs->custom_extensions.received & (1u << i))) {
/* Servers cannot echo extensions that the client didn't send. */
continue;
}
const uint8_t *contents;
size_t contents_len;
int alert = SSL_AD_DECODE_ERROR;
CBB contents_cbb;
switch (ext->add_callback(ssl, ext->value, &contents, &contents_len, &alert,
ext->add_arg)) {
case 1:
if (!CBB_add_u16(extensions, ext->value) ||
!CBB_add_u16_length_prefixed(extensions, &contents_cbb) ||
!CBB_add_bytes(&contents_cbb, contents, contents_len) ||
!CBB_flush(extensions)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
ERR_add_error_dataf("extension: %u", (unsigned) ext->value);
if (ext->free_callback && 0 < contents_len) {
ext->free_callback(ssl, ext->value, contents, ext->add_arg);
}
return 0;
}
if (ext->free_callback && 0 < contents_len) {
ext->free_callback(ssl, ext->value, contents, ext->add_arg);
}
if (!ssl->server) {
assert((ssl->s3->hs->custom_extensions.sent & (1u << i)) == 0);
ssl->s3->hs->custom_extensions.sent |= (1u << i);
}
break;
case 0:
break;
default:
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
OPENSSL_PUT_ERROR(SSL, SSL_R_CUSTOM_EXTENSION_ERROR);
ERR_add_error_dataf("extension: %u", (unsigned) ext->value);
return 0;
}
}
return 1;
}
int custom_ext_add_clienthello(SSL *ssl, CBB *extensions) {
return custom_ext_add_hello(ssl, extensions);
}
int custom_ext_parse_serverhello(SSL *ssl, int *out_alert, uint16_t value,
const CBS *extension) {
unsigned index;
const SSL_CUSTOM_EXTENSION *ext =
custom_ext_find(ssl->ctx->client_custom_extensions, &index, value);
if (/* Unknown extensions are not allowed in a ServerHello. */
ext == NULL ||
/* Also, if we didn't send the extension, that's also unacceptable. */
!(ssl->s3->hs->custom_extensions.sent & (1u << index))) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
ERR_add_error_dataf("extension: %u", (unsigned)value);
*out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
return 0;
}
if (ext->parse_callback != NULL &&
!ext->parse_callback(ssl, value, CBS_data(extension), CBS_len(extension),
out_alert, ext->parse_arg)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CUSTOM_EXTENSION_ERROR);
ERR_add_error_dataf("extension: %u", (unsigned)ext->value);
return 0;
}
return 1;
}
int custom_ext_parse_clienthello(SSL *ssl, int *out_alert, uint16_t value,
const CBS *extension) {
unsigned index;
const SSL_CUSTOM_EXTENSION *ext =
custom_ext_find(ssl->ctx->server_custom_extensions, &index, value);
if (ext == NULL) {
return 1;
}
assert((ssl->s3->hs->custom_extensions.received & (1u << index)) == 0);
ssl->s3->hs->custom_extensions.received |= (1u << index);
if (ext->parse_callback &&
!ext->parse_callback(ssl, value, CBS_data(extension), CBS_len(extension),
out_alert, ext->parse_arg)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CUSTOM_EXTENSION_ERROR);
ERR_add_error_dataf("extension: %u", (unsigned)ext->value);
return 0;
}
return 1;
}
int custom_ext_add_serverhello(SSL *ssl, CBB *extensions) {
return custom_ext_add_hello(ssl, extensions);
}
/* MAX_NUM_CUSTOM_EXTENSIONS is the maximum number of custom extensions that
* can be set on an |SSL_CTX|. It's determined by the size of the bitset used
* to track when an extension has been sent. */
#define MAX_NUM_CUSTOM_EXTENSIONS \
(sizeof(((SSL_HANDSHAKE *)NULL)->custom_extensions.sent) * 8)
static int custom_ext_append(STACK_OF(SSL_CUSTOM_EXTENSION) **stack,
unsigned extension_value,
SSL_custom_ext_add_cb add_cb,
SSL_custom_ext_free_cb free_cb, void *add_arg,
SSL_custom_ext_parse_cb parse_cb,
void *parse_arg) {
if (add_cb == NULL ||
0xffff < extension_value ||
SSL_extension_supported(extension_value) ||
/* Specifying a free callback without an add callback is nonsensical
* and an error. */
(*stack != NULL &&
(MAX_NUM_CUSTOM_EXTENSIONS <= sk_SSL_CUSTOM_EXTENSION_num(*stack) ||
custom_ext_find(*stack, NULL, extension_value) != NULL))) {
return 0;
}
SSL_CUSTOM_EXTENSION *ext = OPENSSL_malloc(sizeof(SSL_CUSTOM_EXTENSION));
if (ext == NULL) {
return 0;
}
ext->add_callback = add_cb;
ext->add_arg = add_arg;
ext->free_callback = free_cb;
ext->parse_callback = parse_cb;
ext->parse_arg = parse_arg;
ext->value = extension_value;
if (*stack == NULL) {
*stack = sk_SSL_CUSTOM_EXTENSION_new_null();
if (*stack == NULL) {
SSL_CUSTOM_EXTENSION_free(ext);
return 0;
}
}
if (!sk_SSL_CUSTOM_EXTENSION_push(*stack, ext)) {
SSL_CUSTOM_EXTENSION_free(ext);
if (sk_SSL_CUSTOM_EXTENSION_num(*stack) == 0) {
sk_SSL_CUSTOM_EXTENSION_free(*stack);
*stack = NULL;
}
return 0;
}
return 1;
}
int SSL_CTX_add_client_custom_ext(SSL_CTX *ctx, unsigned extension_value,
SSL_custom_ext_add_cb add_cb,
SSL_custom_ext_free_cb free_cb, void *add_arg,
SSL_custom_ext_parse_cb parse_cb,
void *parse_arg) {
return custom_ext_append(&ctx->client_custom_extensions, extension_value,
add_cb ? add_cb : default_add_callback, free_cb,
add_arg, parse_cb, parse_arg);
}
int SSL_CTX_add_server_custom_ext(SSL_CTX *ctx, unsigned extension_value,
SSL_custom_ext_add_cb add_cb,
SSL_custom_ext_free_cb free_cb, void *add_arg,
SSL_custom_ext_parse_cb parse_cb,
void *parse_arg) {
return custom_ext_append(&ctx->server_custom_extensions, extension_value,
add_cb ? add_cb : default_add_callback, free_cb,
add_arg, parse_cb, parse_arg);
}
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