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openssl/ssl/statem/extensions_clnt.c
Matt Caswell 6dd083fd68 Move client parsing of ServerHello extensions into new framework 
Perl changes reviewed by Richard Levitte. Non-perl changes reviewed by Rich
Salz

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
2016-12-08 17:18:25 +00:00

608 lines
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/*
* Copyright 2016 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
*/
#include <assert.h>
#include "../ssl_locl.h"
#include "statem_locl.h"
/*
* Parse the server's renegotiation binding and abort if it's not right
*/
int tls_parse_server_renegotiate(SSL *s, PACKET *pkt, int *al)
{
size_t expected_len = s->s3->previous_client_finished_len
+ s->s3->previous_server_finished_len;
size_t ilen;
const unsigned char *data;
/* Check for logic errors */
assert(expected_len == 0 || s->s3->previous_client_finished_len != 0);
assert(expected_len == 0 || s->s3->previous_server_finished_len != 0);
/* Parse the length byte */
if (!PACKET_get_1_len(pkt, &ilen)) {
SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
SSL_R_RENEGOTIATION_ENCODING_ERR);
*al = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
/* Consistency check */
if (PACKET_remaining(pkt) != ilen) {
SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
SSL_R_RENEGOTIATION_ENCODING_ERR);
*al = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
/* Check that the extension matches */
if (ilen != expected_len) {
SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
SSL_R_RENEGOTIATION_MISMATCH);
*al = SSL_AD_HANDSHAKE_FAILURE;
return 0;
}
if (!PACKET_get_bytes(pkt, &data, s->s3->previous_client_finished_len)
|| memcmp(data, s->s3->previous_client_finished,
s->s3->previous_client_finished_len) != 0) {
SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
SSL_R_RENEGOTIATION_MISMATCH);
*al = SSL_AD_HANDSHAKE_FAILURE;
return 0;
}
if (!PACKET_get_bytes(pkt, &data, s->s3->previous_server_finished_len)
|| memcmp(data, s->s3->previous_server_finished,
s->s3->previous_server_finished_len) != 0) {
SSLerr(SSL_F_TLS_PARSE_SERVER_RENEGOTIATE,
SSL_R_RENEGOTIATION_MISMATCH);
*al = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
s->s3->send_connection_binding = 1;
return 1;
}
int tls_parse_server_server_name(SSL *s, PACKET *pkt, int *al)
{
if (s->tlsext_hostname == NULL || PACKET_remaining(pkt) > 0) {
*al = SSL_AD_UNRECOGNIZED_NAME;
return 0;
}
if (!s->hit) {
if (s->session->tlsext_hostname != NULL) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
s->session->tlsext_hostname = OPENSSL_strdup(s->tlsext_hostname);
if (s->session->tlsext_hostname == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
}
return 1;
}
#ifndef OPENSSL_NO_EC
int tls_parse_server_ec_pt_formats(SSL *s, PACKET *pkt, int *al)
{
unsigned int ecpointformatlist_length;
PACKET ecptformatlist;
if (!PACKET_as_length_prefixed_1(pkt, &ecptformatlist)) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
if (!s->hit) {
ecpointformatlist_length = PACKET_remaining(&ecptformatlist);
s->session->tlsext_ecpointformatlist_length = 0;
OPENSSL_free(s->session->tlsext_ecpointformatlist);
s->session->tlsext_ecpointformatlist =
OPENSSL_malloc(ecpointformatlist_length);
if (s->session->tlsext_ecpointformatlist == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
s->session->tlsext_ecpointformatlist_length = ecpointformatlist_length;
if (!PACKET_copy_bytes(&ecptformatlist,
s->session->tlsext_ecpointformatlist,
ecpointformatlist_length)) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
}
return 1;
}
#endif
int tls_parse_server_session_ticket(SSL *s, PACKET *pkt, int *al)
{
if (s->tls_session_ticket_ext_cb &&
!s->tls_session_ticket_ext_cb(s, PACKET_data(pkt),
PACKET_remaining(pkt),
s->tls_session_ticket_ext_cb_arg)) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
if (!tls_use_ticket(s) || PACKET_remaining(pkt) > 0) {
*al = SSL_AD_UNSUPPORTED_EXTENSION;
return 0;
}
s->tlsext_ticket_expected = 1;
return 1;
}
int tls_parse_server_status_request(SSL *s, PACKET *pkt, int *al)
{
/*
* MUST be empty and only sent if we've requested a status
* request message.
*/
if (s->tlsext_status_type == -1 || PACKET_remaining(pkt) > 0) {
*al = SSL_AD_UNSUPPORTED_EXTENSION;
return 0;
}
/* Set flag to expect CertificateStatus message */
s->tlsext_status_expected = 1;
return 1;
}
#ifndef OPENSSL_NO_CT
int tls_parse_server_sct(SSL *s, PACKET *pkt, int *al)
{
/*
* Only take it if we asked for it - i.e if there is no CT validation
* callback set, then a custom extension MAY be processing it, so we
* need to let control continue to flow to that.
*/
if (s->ct_validation_callback != NULL) {
size_t size = PACKET_remaining(pkt);
/* Simply copy it off for later processing */
if (s->tlsext_scts != NULL) {
OPENSSL_free(s->tlsext_scts);
s->tlsext_scts = NULL;
}
s->tlsext_scts_len = size;
if (size > 0) {
s->tlsext_scts = OPENSSL_malloc(size);
if (s->tlsext_scts == NULL
|| !PACKET_copy_bytes(pkt, s->tlsext_scts, size)) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
}
} else {
if (custom_ext_parse(s, 0, TLSEXT_TYPE_signed_certificate_timestamp,
PACKET_data(pkt), PACKET_remaining(pkt), al) <= 0)
return 0;
}
return 1;
}
#endif
#ifndef OPENSSL_NO_NEXTPROTONEG
/*
* ssl_next_proto_validate validates a Next Protocol Negotiation block. No
* elements of zero length are allowed and the set of elements must exactly
* fill the length of the block. Returns 1 on success or 0 on failure.
*/
static int ssl_next_proto_validate(PACKET *pkt)
{
PACKET tmp_protocol;
while (PACKET_remaining(pkt)) {
if (!PACKET_get_length_prefixed_1(pkt, &tmp_protocol)
|| PACKET_remaining(&tmp_protocol) == 0)
return 0;
}
return 1;
}
int tls_parse_server_npn(SSL *s, PACKET *pkt, int *al)
{
unsigned char *selected;
unsigned char selected_len;
PACKET tmppkt;
if (s->s3->tmp.finish_md_len != 0)
return 1;
/* We must have requested it. */
if (s->ctx->next_proto_select_cb == NULL) {
*al = SSL_AD_UNSUPPORTED_EXTENSION;
return 0;
}
/* The data must be valid */
tmppkt = *pkt;
if (!ssl_next_proto_validate(&tmppkt)) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
if (s->ctx->next_proto_select_cb(s, &selected, &selected_len,
PACKET_data(pkt),
PACKET_remaining(pkt),
s->ctx->next_proto_select_cb_arg) !=
SSL_TLSEXT_ERR_OK) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
/*
* Could be non-NULL if server has sent multiple NPN extensions in
* a single Serverhello
*/
OPENSSL_free(s->next_proto_negotiated);
s->next_proto_negotiated = OPENSSL_malloc(selected_len);
if (s->next_proto_negotiated == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
memcpy(s->next_proto_negotiated, selected, selected_len);
s->next_proto_negotiated_len = selected_len;
s->s3->next_proto_neg_seen = 1;
return 1;
}
#endif
int tls_parse_server_alpn(SSL *s, PACKET *pkt, int *al)
{
size_t len;
/* We must have requested it. */
if (!s->s3->alpn_sent) {
*al = SSL_AD_UNSUPPORTED_EXTENSION;
return 0;
}
/*-
* The extension data consists of:
* uint16 list_length
* uint8 proto_length;
* uint8 proto[proto_length];
*/
if (!PACKET_get_net_2_len(pkt, &len)
|| PACKET_remaining(pkt) != len || !PACKET_get_1_len(pkt, &len)
|| PACKET_remaining(pkt) != len) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = OPENSSL_malloc(len);
if (s->s3->alpn_selected == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
if (!PACKET_copy_bytes(pkt, s->s3->alpn_selected, len)) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
s->s3->alpn_selected_len = len;
return 1;
}
#ifndef OPENSSL_NO_SRTP
int tls_parse_server_use_srtp(SSL *s, PACKET *pkt, int *al)
{
unsigned int id, ct, mki;
int i;
STACK_OF(SRTP_PROTECTION_PROFILE) *clnt;
SRTP_PROTECTION_PROFILE *prof;
if (!PACKET_get_net_2(pkt, &ct)
|| ct != 2 || !PACKET_get_net_2(pkt, &id)
|| !PACKET_get_1(pkt, &mki)
|| PACKET_remaining(pkt) != 0) {
SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP,
SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
*al = SSL_AD_DECODE_ERROR;
return 0;
}
if (mki != 0) {
/* Must be no MKI, since we never offer one */
SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP, SSL_R_BAD_SRTP_MKI_VALUE);
*al = SSL_AD_ILLEGAL_PARAMETER;
return 0;
}
clnt = SSL_get_srtp_profiles(s);
/* Throw an error if the server gave us an unsolicited extension */
if (clnt == NULL) {
SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP, SSL_R_NO_SRTP_PROFILES);
*al = SSL_AD_DECODE_ERROR;
return 0;
}
/*
* Check to see if the server gave us something we support (and
* presumably offered)
*/
for (i = 0; i < sk_SRTP_PROTECTION_PROFILE_num(clnt); i++) {
prof = sk_SRTP_PROTECTION_PROFILE_value(clnt, i);
if (prof->id == id) {
s->srtp_profile = prof;
*al = 0;
return 1;
}
}
SSLerr(SSL_F_TLS_PARSE_SERVER_USE_SRTP,
SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
*al = SSL_AD_DECODE_ERROR;
return 0;
}
#endif
int tls_parse_server_etm(SSL *s, PACKET *pkt, int *al)
{
/* Ignore if inappropriate ciphersuite */
if (!(s->options & SSL_OP_NO_ENCRYPT_THEN_MAC)
&& s->s3->tmp.new_cipher->algorithm_mac != SSL_AEAD
&& s->s3->tmp.new_cipher->algorithm_enc != SSL_RC4)
s->s3->flags |= TLS1_FLAGS_ENCRYPT_THEN_MAC;
return 1;
}
int tls_parse_server_ems(SSL *s, PACKET *pkt, int *al)
{
s->s3->flags |= TLS1_FLAGS_RECEIVED_EXTMS;
if (!s->hit)
s->session->flags |= SSL_SESS_FLAG_EXTMS;
return 1;
}
int tls_parse_server_key_share(SSL *s, PACKET *pkt, int *al)
{
unsigned int group_id;
PACKET encoded_pt;
EVP_PKEY *ckey = s->s3->tmp.pkey, *skey = NULL;
/* Sanity check */
if (ckey == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, ERR_R_INTERNAL_ERROR);
return 0;
}
if (!PACKET_get_net_2(pkt, &group_id)) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_LENGTH_MISMATCH);
return 0;
}
if (group_id != s->s3->group_id) {
/*
* This isn't for the group that we sent in the original
* key_share!
*/
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_BAD_KEY_SHARE);
return 0;
}
if (!PACKET_as_length_prefixed_2(pkt, &encoded_pt)
|| PACKET_remaining(&encoded_pt) == 0) {
*al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_LENGTH_MISMATCH);
return 0;
}
skey = ssl_generate_pkey(ckey);
if (skey == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!EVP_PKEY_set1_tls_encodedpoint(skey, PACKET_data(&encoded_pt),
PACKET_remaining(&encoded_pt))) {
*al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, SSL_R_BAD_ECPOINT);
return 0;
}
if (ssl_derive(s, ckey, skey, 1) == 0) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_TLS_PARSE_SERVER_KEY_SHARE, ERR_R_INTERNAL_ERROR);
EVP_PKEY_free(skey);
return 0;
}
EVP_PKEY_free(skey);
return 1;
}
static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
{
size_t num_extensions = 0;
RAW_EXTENSION *extensions = NULL;
PACKET extpkt;
#ifndef OPENSSL_NO_NEXTPROTONEG
s->s3->next_proto_neg_seen = 0;
#endif
s->tlsext_ticket_expected = 0;
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = NULL;
s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
if (!PACKET_as_length_prefixed_2(pkt, &extpkt)) {
/* Extensions block may be completely absent in SSLv3 */
if (s->version != SSL3_VERSION || PACKET_remaining(pkt) != 0) {
*al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_BAD_LENGTH);
return 0;
}
PACKET_null_init(&extpkt);
}
/*
* TODO(TLS1.3): We give multiple contexts for now until we're ready to
* give something more specific
*/
if (!tls_collect_extensions(s, &extpkt, EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| EXT_TLS1_3_CERTIFICATE,
&extensions, &num_extensions, al))
return 0;
/*
* Determine if we need to see RI. Strictly speaking if we want to avoid
* an attack we should *always* see RI even on initial server hello
* 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 so for the immediate future tolerate RI absence
*/
if (!(s->options & SSL_OP_LEGACY_SERVER_CONNECT)
&& !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)
&& tls_get_extension_by_type(extensions, num_extensions,
TLSEXT_TYPE_renegotiate) == NULL) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT,
SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
return 0;
}
if (!tls_parse_all_extensions(s, EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| EXT_TLS1_3_CERTIFICATE,
extensions, num_extensions, al))
return 0;
if (s->hit) {
/*
* Check extended master secret extension is consistent with
* original session.
*/
if (!(s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) !=
!(s->session->flags & SSL_SESS_FLAG_EXTMS)) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_INCONSISTENT_EXTMS);
return 0;
}
}
return 1;
}
static int ssl_check_serverhello_tlsext(SSL *s)
{
int ret = SSL_TLSEXT_ERR_NOACK;
int al = SSL_AD_UNRECOGNIZED_NAME;
#ifndef OPENSSL_NO_EC
/*
* If we are client and using an elliptic curve cryptography cipher
* suite, then if server returns an EC point formats lists extension it
* must contain uncompressed.
*/
unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
if ((s->tlsext_ecpointformatlist != NULL)
&& (s->tlsext_ecpointformatlist_length > 0)
&& (s->session->tlsext_ecpointformatlist != NULL)
&& (s->session->tlsext_ecpointformatlist_length > 0)
&& ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))) {
/* we are using an ECC cipher */
size_t i;
unsigned char *list;
int found_uncompressed = 0;
list = s->session->tlsext_ecpointformatlist;
for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++) {
if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
found_uncompressed = 1;
break;
}
}
if (!found_uncompressed) {
SSLerr(SSL_F_SSL_CHECK_SERVERHELLO_TLSEXT,
SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
return -1;
}
}
ret = SSL_TLSEXT_ERR_OK;
#endif /* OPENSSL_NO_EC */
if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
ret =
s->ctx->tlsext_servername_callback(s, &al,
s->ctx->tlsext_servername_arg);
else if (s->initial_ctx != NULL
&& s->initial_ctx->tlsext_servername_callback != 0)
ret =
s->initial_ctx->tlsext_servername_callback(s, &al,
s->
initial_ctx->tlsext_servername_arg);
/*
* Ensure we get sensible values passed to tlsext_status_cb in the event
* that we don't receive a status message
*/
OPENSSL_free(s->tlsext_ocsp_resp);
s->tlsext_ocsp_resp = NULL;
s->tlsext_ocsp_resplen = 0;
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
return -1;
case SSL_TLSEXT_ERR_ALERT_WARNING:
ssl3_send_alert(s, SSL3_AL_WARNING, al);
return 1;
case SSL_TLSEXT_ERR_NOACK:
s->servername_done = 0;
default:
return 1;
}
}
int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt)
{
int al = -1;
if (s->version < SSL3_VERSION)
return 1;
if (ssl_scan_serverhello_tlsext(s, pkt, &al) <= 0) {
ssl3_send_alert(s, SSL3_AL_FATAL, al);
return 0;
}
if (ssl_check_serverhello_tlsext(s) <= 0) {
SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT, SSL_R_SERVERHELLO_TLSEXT);
return 0;
}
return 1;
}
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