extensions.c
/*
* 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 <string.h>
#include "../ssl_locl.h"
#include "statem_locl.h"
static int final_renegotiate(SSL *s, unsigned int context, int sent,
int *al);
static int init_server_name(SSL *s, unsigned int context);
static int final_server_name(SSL *s, unsigned int context, int sent,
int *al);
#ifndef OPENSSL_NO_EC
static int final_ec_pt_formats(SSL *s, unsigned int context, int sent,
int *al);
#endif
static int init_session_ticket(SSL *s, unsigned int context);
#ifndef OPENSSL_NO_OCSP
static int init_status_request(SSL *s, unsigned int context);
#endif
#ifndef OPENSSL_NO_NEXTPROTONEG
static int init_npn(SSL *s, unsigned int context);
#endif
static int init_alpn(SSL *s, unsigned int context);
static int final_alpn(SSL *s, unsigned int context, int sent, int *al);
static int init_sig_algs(SSL *s, unsigned int context);
#ifndef OPENSSL_NO_SRP
static int init_srp(SSL *s, unsigned int context);
#endif
static int init_etm(SSL *s, unsigned int context);
static int init_ems(SSL *s, unsigned int context);
static int final_ems(SSL *s, unsigned int context, int sent, int *al);
static int init_psk_kex_modes(SSL *s, unsigned int context);
#ifndef OPENSSL_NO_EC
static int final_key_share(SSL *s, unsigned int context, int sent, int *al);
#endif
#ifndef OPENSSL_NO_SRTP
static int init_srtp(SSL *s, unsigned int context);
#endif
static int final_sig_algs(SSL *s, unsigned int context, int sent, int *al);
static int final_early_data(SSL *s, unsigned int context, int sent, int *al);
/* Structure to define a built-in extension */
typedef struct extensions_definition_st {
/* The defined type for the extension */
unsigned int type;
/*
* The context that this extension applies to, e.g. what messages and
* protocol versions
*/
unsigned int context;
/*
* Initialise extension before parsing. Always called for relevant contexts
* even if extension not present
*/
int (*init)(SSL *s, unsigned int context);
/* Parse extension sent from client to server */
int (*parse_ctos)(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al);
/* Parse extension send from server to client */
int (*parse_stoc)(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al);
/* Construct extension sent from server to client */
int (*construct_stoc)(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al);
/* Construct extension sent from client to server */
int (*construct_ctos)(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al);
/*
* Finalise extension after parsing. Always called where an extensions was
* initialised even if the extension was not present. |sent| is set to 1 if
* the extension was seen, or 0 otherwise.
*/
int (*final)(SSL *s, unsigned int context, int sent, int *al);
} EXTENSION_DEFINITION;
/*
* Definitions of all built-in extensions. NOTE: Changes in the number or order
* of these extensions should be mirrored with equivalent changes to the
* indexes ( TLSEXT_IDX_* ) defined in ssl_locl.h.
* Each extension has an initialiser, a client and
* server side parser and a finaliser. The initialiser is called (if the
* extension is relevant to the given context) even if we did not see the
* extension in the message that we received. The parser functions are only
* called if we see the extension in the message. The finalisers are always
* called if the initialiser was called.
* There are also server and client side constructor functions which are always
* called during message construction if the extension is relevant for the
* given context.
* The initialisation, parsing, finalisation and construction functions are
* always called in the order defined in this list. Some extensions may depend
* on others having been processed first, so the order of this list is
* significant.
* The extension context is defined by a series of flags which specify which
* messages the extension is relevant to. These flags also specify whether the
* extension is relevant to a particular protocol or protocol version.
*
* TODO(TLS1.3): Make sure we have a test to check the consistency of these
*/
#define INVALID_EXTENSION { 0x10000, 0, NULL, NULL, NULL, NULL, NULL, NULL }
static const EXTENSION_DEFINITION ext_defs[] = {
{
TLSEXT_TYPE_renegotiate,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_SSL3_ALLOWED
| EXT_TLS1_2_AND_BELOW_ONLY,
NULL, tls_parse_ctos_renegotiate, tls_parse_stoc_renegotiate,
tls_construct_stoc_renegotiate, tls_construct_ctos_renegotiate,
final_renegotiate
},
{
TLSEXT_TYPE_server_name,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS,
init_server_name,
tls_parse_ctos_server_name, tls_parse_stoc_server_name,
tls_construct_stoc_server_name, tls_construct_ctos_server_name,
final_server_name
},
#ifndef OPENSSL_NO_SRP
{
TLSEXT_TYPE_srp,
EXT_CLIENT_HELLO | EXT_TLS1_2_AND_BELOW_ONLY,
init_srp, tls_parse_ctos_srp, NULL, NULL, tls_construct_ctos_srp, NULL
},
#else
INVALID_EXTENSION,
#endif
{
TLSEXT_TYPE_early_data_info,
EXT_TLS1_3_NEW_SESSION_TICKET,
NULL, NULL, tls_parse_stoc_early_data_info,
tls_construct_stoc_early_data_info, NULL, NULL
},
#ifndef OPENSSL_NO_EC
{
TLSEXT_TYPE_ec_point_formats,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY,
NULL, tls_parse_ctos_ec_pt_formats, tls_parse_stoc_ec_pt_formats,
tls_construct_stoc_ec_pt_formats, tls_construct_ctos_ec_pt_formats,
final_ec_pt_formats
},
{
TLSEXT_TYPE_supported_groups,
EXT_CLIENT_HELLO | EXT_TLS1_3_ENCRYPTED_EXTENSIONS,
NULL, tls_parse_ctos_supported_groups, NULL,
NULL /* TODO(TLS1.3): Need to add this */,
tls_construct_ctos_supported_groups, NULL
},
#else
INVALID_EXTENSION,
INVALID_EXTENSION,
#endif
{
TLSEXT_TYPE_session_ticket,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY,
init_session_ticket, tls_parse_ctos_session_ticket,
tls_parse_stoc_session_ticket, tls_construct_stoc_session_ticket,
tls_construct_ctos_session_ticket, NULL
},
{
TLSEXT_TYPE_signature_algorithms,
EXT_CLIENT_HELLO,
init_sig_algs, tls_parse_ctos_sig_algs, NULL, NULL,
tls_construct_ctos_sig_algs, final_sig_algs
},
#ifndef OPENSSL_NO_OCSP
{
TLSEXT_TYPE_status_request,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_CERTIFICATE,
init_status_request, tls_parse_ctos_status_request,
tls_parse_stoc_status_request, tls_construct_stoc_status_request,
tls_construct_ctos_status_request, NULL
},
#else
INVALID_EXTENSION,
#endif
#ifndef OPENSSL_NO_NEXTPROTONEG
{
TLSEXT_TYPE_next_proto_neg,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY,
init_npn, tls_parse_ctos_npn, tls_parse_stoc_npn,
tls_construct_stoc_next_proto_neg, tls_construct_ctos_npn, NULL
},
#else
INVALID_EXTENSION,
#endif
{
/*
* Must appear in this list after server_name so that finalisation
* happens after server_name callbacks
*/
TLSEXT_TYPE_application_layer_protocol_negotiation,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS,
init_alpn, tls_parse_ctos_alpn, tls_parse_stoc_alpn,
tls_construct_stoc_alpn, tls_construct_ctos_alpn, final_alpn
},
#ifndef OPENSSL_NO_SRTP
{
TLSEXT_TYPE_use_srtp,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS | EXT_DTLS_ONLY,
init_srtp, tls_parse_ctos_use_srtp, tls_parse_stoc_use_srtp,
tls_construct_stoc_use_srtp, tls_construct_ctos_use_srtp, NULL
},
#else
INVALID_EXTENSION,
#endif
{
TLSEXT_TYPE_encrypt_then_mac,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY | EXT_SSL3_ALLOWED,
init_etm, tls_parse_ctos_etm, tls_parse_stoc_etm,
tls_construct_stoc_etm, tls_construct_ctos_etm, NULL
},
#ifndef OPENSSL_NO_CT
{
TLSEXT_TYPE_signed_certificate_timestamp,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_CERTIFICATE,
NULL,
/*
* No server side support for this, but can be provided by a custom
* extension. This is an exception to the rule that custom extensions
* cannot override built in ones.
*/
NULL, tls_parse_stoc_sct, NULL, tls_construct_ctos_sct, NULL
},
#else
INVALID_EXTENSION,
#endif
{
TLSEXT_TYPE_extended_master_secret,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY,
init_ems, tls_parse_ctos_ems, tls_parse_stoc_ems,
tls_construct_stoc_ems, tls_construct_ctos_ems, final_ems
},
{
TLSEXT_TYPE_supported_versions,
EXT_CLIENT_HELLO | EXT_TLS_IMPLEMENTATION_ONLY | EXT_TLS1_3_ONLY,
NULL,
/* Processed inline as part of version selection */
NULL, NULL, NULL, tls_construct_ctos_supported_versions, NULL
},
{
TLSEXT_TYPE_psk_kex_modes,
EXT_CLIENT_HELLO | EXT_TLS_IMPLEMENTATION_ONLY | EXT_TLS1_3_ONLY,
init_psk_kex_modes, tls_parse_ctos_psk_kex_modes, NULL, NULL,
tls_construct_ctos_psk_kex_modes, NULL
},
#ifndef OPENSSL_NO_EC
{
/*
* Must be in this list after supported_groups. We need that to have
* been parsed before we do this one.
*/
TLSEXT_TYPE_key_share,
EXT_CLIENT_HELLO | EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_HELLO_RETRY_REQUEST | EXT_TLS_IMPLEMENTATION_ONLY
| EXT_TLS1_3_ONLY,
NULL, tls_parse_ctos_key_share, tls_parse_stoc_key_share,
tls_construct_stoc_key_share, tls_construct_ctos_key_share,
final_key_share
},
#endif
{
TLSEXT_TYPE_cookie,
EXT_CLIENT_HELLO | EXT_TLS1_3_HELLO_RETRY_REQUEST
| EXT_TLS_IMPLEMENTATION_ONLY | EXT_TLS1_3_ONLY,
NULL, NULL, tls_parse_stoc_cookie, NULL, tls_construct_ctos_cookie,
NULL
},
{
/*
* Special unsolicited ServerHello extension only used when
* SSL_OP_CRYPTOPRO_TLSEXT_BUG is set
*/
TLSEXT_TYPE_cryptopro_bug,
EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY,
NULL, NULL, NULL, tls_construct_stoc_cryptopro_bug, NULL, NULL
},
{
TLSEXT_TYPE_early_data,
EXT_CLIENT_HELLO | EXT_TLS1_3_ENCRYPTED_EXTENSIONS,
NULL, tls_parse_ctos_early_data, tls_parse_stoc_early_data,
tls_construct_stoc_early_data, tls_construct_ctos_early_data,
final_early_data
},
{
/* Must be immediately before pre_shared_key */
/* TODO(TLS1.3): Fix me */
TLSEXT_TYPE_padding,
EXT_CLIENT_HELLO,
NULL,
/* We send this, but don't read it */
NULL, NULL, NULL, tls_construct_ctos_padding, NULL
},
{
/* Required by the TLSv1.3 spec to always be the last extension */
TLSEXT_TYPE_psk,
EXT_CLIENT_HELLO | EXT_TLS1_3_SERVER_HELLO | EXT_TLS_IMPLEMENTATION_ONLY
| EXT_TLS1_3_ONLY,
NULL, tls_parse_ctos_psk, tls_parse_stoc_psk, tls_construct_stoc_psk,
tls_construct_ctos_psk, NULL
}
};
/*
* Verify whether we are allowed to use the extension |type| in the current
* |context|. Returns 1 to indicate the extension is allowed or unknown or 0 to
* indicate the extension is not allowed. If returning 1 then |*found| is set to
* 1 if we found a definition for the extension, and |*idx| is set to its index
*/
static int verify_extension(SSL *s, unsigned int context, unsigned int type,
custom_ext_methods *meths, RAW_EXTENSION *rawexlist,
RAW_EXTENSION **found)
{
size_t i;
size_t builtin_num = OSSL_NELEM(ext_defs);
const EXTENSION_DEFINITION *thisext;
for (i = 0, thisext = ext_defs; i < builtin_num; i++, thisext++) {
if (type == thisext->type) {
/* Check we're allowed to use this extension in this context */
if ((context & thisext->context) == 0)
return 0;
if (SSL_IS_DTLS(s)) {
if ((thisext->context & EXT_TLS_ONLY) != 0)
return 0;
} else if ((thisext->context & EXT_DTLS_ONLY) != 0) {
return 0;
}
*found = &rawexlist[i];
return 1;
}
}
if ((context & (EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO)) == 0) {
/*
* Custom extensions only apply to <=TLS1.2. This extension is unknown
* in this context - we allow it
*/
*found = NULL;
return 1;
}
/* Check the custom extensions */
if (meths != NULL) {
for (i = builtin_num; i < builtin_num + meths->meths_count; i++) {
if (meths->meths[i - builtin_num].ext_type == type) {
*found = &rawexlist[i];
return 1;
}
}
}
/* Unknown extension. We allow it */
*found = NULL;
return 1;
}
/*
* Check whether the context defined for an extension |extctx| means whether
* the extension is relevant for the current context |thisctx| or not. Returns
* 1 if the extension is relevant for this context, and 0 otherwise
*/
static int extension_is_relevant(SSL *s, unsigned int extctx,
unsigned int thisctx)
{
if ((SSL_IS_DTLS(s)
&& (extctx & EXT_TLS_IMPLEMENTATION_ONLY) != 0)
|| (s->version == SSL3_VERSION
&& (extctx & EXT_SSL3_ALLOWED) == 0)
|| (SSL_IS_TLS13(s)
&& (extctx & EXT_TLS1_2_AND_BELOW_ONLY) != 0)
|| (!SSL_IS_TLS13(s) && (extctx & EXT_TLS1_3_ONLY) != 0))
return 0;
return 1;
}
/*
* Gather a list of all the extensions from the data in |packet]. |context|
* tells us which message this extension is for. The raw extension data is
* stored in |*res| on success. In the event of an error the alert type to use
* is stored in |*al|. We don't actually process the content of the extensions
* yet, except to check their types. This function also runs the initialiser
* functions for all known extensions (whether we have collected them or not).
* If successful the caller is responsible for freeing the contents of |*res|.
*
* 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 returns 1 if all extensions are unique and we have parsed their
* types, and 0 if the extensions contain duplicates, could not be successfully
* found, or an internal error occurred. We only check duplicates for
* extensions that we know about. We ignore others.
*/
int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
RAW_EXTENSION **res, int *al, size_t *len)
{
PACKET extensions = *packet;
size_t i = 0;
size_t num_exts;
custom_ext_methods *exts = NULL;
RAW_EXTENSION *raw_extensions = NULL;
const EXTENSION_DEFINITION *thisexd;
*res = NULL;
/*
* Initialise server side custom extensions. Client side is done during
* construction of extensions for the ClientHello.
*/
if ((context & EXT_CLIENT_HELLO) != 0) {
exts = &s->cert->srv_ext;
custom_ext_init(&s->cert->srv_ext);
} else if ((context & EXT_TLS1_2_SERVER_HELLO) != 0) {
exts = &s->cert->cli_ext;
}
num_exts = OSSL_NELEM(ext_defs) + (exts != NULL ? exts->meths_count : 0);
raw_extensions = OPENSSL_zalloc(num_exts * sizeof(*raw_extensions));
if (raw_extensions == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, ERR_R_MALLOC_FAILURE);
return 0;
}
while (PACKET_remaining(&extensions) > 0) {
unsigned int type;
PACKET extension;
RAW_EXTENSION *thisex;
if (!PACKET_get_net_2(&extensions, &type) ||
!PACKET_get_length_prefixed_2(&extensions, &extension)) {
SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_BAD_EXTENSION);
*al = SSL_AD_DECODE_ERROR;
goto err;
}
/*
* Verify this extension is allowed. We only check duplicates for
* extensions that we recognise. We also have a special case for the
* PSK extension, which must be the last one in the ClientHello.
*/
if (!verify_extension(s, context, type, exts, raw_extensions, &thisex)
|| (thisex != NULL && thisex->present == 1)
|| (type == TLSEXT_TYPE_psk
&& (context & EXT_CLIENT_HELLO) != 0
&& PACKET_remaining(&extensions) != 0)) {
SSLerr(SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_BAD_EXTENSION);
*al = SSL_AD_ILLEGAL_PARAMETER;
goto err;
}
if (thisex != NULL) {
thisex->data = extension;
thisex->present = 1;
thisex->type = type;
}
}
/*
* Initialise all known extensions relevant to this context, whether we have
* found them or not
*/
for (thisexd = ext_defs, i = 0; i < OSSL_NELEM(ext_defs); i++, thisexd++) {
if(thisexd->init != NULL && (thisexd->context & context) != 0
&& extension_is_relevant(s, thisexd->context, context)
&& !thisexd->init(s, context)) {
*al = SSL_AD_INTERNAL_ERROR;
goto err;
}
}
*res = raw_extensions;
if (len != NULL)
*len = num_exts;
return 1;
err:
OPENSSL_free(raw_extensions);
return 0;
}
/*
* Runs the parser for a given extension with index |idx|. |exts| contains the
* list of all parsed extensions previously collected by
* tls_collect_extensions(). The parser is only run if it is applicable for the
* given |context| and the parser has not already been run. If this is for a
* Certificate message, then we also provide the parser with the relevant
* Certificate |x| and its position in the |chainidx| with 0 being the first
* Certificate. Returns 1 on success or 0 on failure. In the event of a failure
* |*al| is populated with a suitable alert code. If an extension is not present
* this counted as success.
*/
int tls_parse_extension(SSL *s, TLSEXT_INDEX idx, int context,
RAW_EXTENSION *exts, X509 *x, size_t chainidx, int *al)
{
RAW_EXTENSION *currext = &exts[idx];
int (*parser)(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al) = NULL;
/* Skip if the extension is not present */
if (!currext->present)
return 1;
if (s->ext.debug_cb)
s->ext.debug_cb(s, !s->server, currext->type,
PACKET_data(&currext->data),
PACKET_remaining(&currext->data),
s->ext.debug_arg);
/* Skip if we've already parsed this extension */
if (currext->parsed)
return 1;
currext->parsed = 1;
if (idx < OSSL_NELEM(ext_defs)) {
/* We are handling a built-in extension */
const EXTENSION_DEFINITION *extdef = &ext_defs[idx];
/* Check if extension is defined for our protocol. If not, skip */
if (!extension_is_relevant(s, extdef->context, context))
return 1;
parser = s->server ? extdef->parse_ctos : extdef->parse_stoc;
if (parser != NULL)
return parser(s, &currext->data, context, x, chainidx, al);
/*
* If the parser is NULL we fall through to the custom extension
* processing
*/
}
/*
* This is a custom extension. We only allow this if it is a non
* resumed session on the server side.
*chain
* TODO(TLS1.3): We only allow old style <=TLS1.2 custom extensions.
* We're going to need a new mechanism for TLS1.3 to specify which
* messages to add the custom extensions to.
*/
if ((!s->hit || !s->server)
&& (context
& (EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO)) != 0
&& custom_ext_parse(s, s->server, currext->type,
PACKET_data(&currext->data),
PACKET_remaining(&currext->data),
al) <= 0)
return 0;
return 1;
}
/*
* Parse all remaining extensions that have not yet been parsed. Also calls the
* finalisation for all extensions at the end, whether we collected them or not.
* Returns 1 for success or 0 for failure. If we are working on a Certificate
* message then we also pass the Certificate |x| and its position in the
* |chainidx|, with 0 being the first certificate. On failure, |*al| is
* populated with a suitable alert code.
*/
int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts, X509 *x,
size_t chainidx, int *al)
{
size_t i, numexts = OSSL_NELEM(ext_defs);
const EXTENSION_DEFINITION *thisexd;
/* Calculate the number of extensions in the extensions list */
if ((context & EXT_CLIENT_HELLO) != 0) {
numexts += s->cert->srv_ext.meths_count;
} else if ((context & EXT_TLS1_2_SERVER_HELLO) != 0) {
numexts += s->cert->cli_ext.meths_count;
}
/* Parse each extension in turn */
for (i = 0; i < numexts; i++) {
if (!tls_parse_extension(s, i, context, exts, x, chainidx, al))
return 0;
}
/*
* Finalise all known extensions relevant to this context, whether we have
* found them or not
*/
for (i = 0, thisexd = ext_defs; i < OSSL_NELEM(ext_defs); i++, thisexd++) {
if(thisexd->final != NULL
&& (thisexd->context & context) != 0
&& !thisexd->final(s, context, exts[i].present, al))
return 0;
}
return 1;
}
/*
* Construct all the extensions relevant to the current |context| and write
* them to |pkt|. If this is an extension for a Certificate in a Certificate
* message, then |x| will be set to the Certificate we are handling, and
* |chainidx| will indicate the position in the chainidx we are processing (with
* 0 being the first in the chain). Returns 1 on success or 0 on failure. If a
* failure occurs then |al| is populated with a suitable alert code. On a
* failure construction stops at the first extension to fail to construct.
*/
int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
X509 *x, size_t chainidx, int *al)
{
size_t i;
int addcustom = 0, min_version, max_version = 0, reason, tmpal;
const EXTENSION_DEFINITION *thisexd;
/*
* Normally if something goes wrong during construction it's an internal
* error. We can always override this later.
*/
tmpal = SSL_AD_INTERNAL_ERROR;
if (!WPACKET_start_sub_packet_u16(pkt)
/*
* If extensions are of zero length then we don't even add the
* extensions length bytes to a ClientHello/ServerHello in SSLv3
*/
|| ((context & (EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO)) != 0
&& s->version == SSL3_VERSION
&& !WPACKET_set_flags(pkt,
WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH))) {
SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
goto err;
}
if ((context & EXT_CLIENT_HELLO) != 0) {
reason = ssl_get_min_max_version(s, &min_version, &max_version);
if (reason != 0) {
SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, reason);
goto err;
}
}
/* Add custom extensions first */
if ((context & EXT_CLIENT_HELLO) != 0) {
custom_ext_init(&s->cert->cli_ext);
addcustom = 1;
} else if ((context & EXT_TLS1_2_SERVER_HELLO) != 0) {
/*
* We already initialised the custom extensions during ClientHello
* parsing.
*
* TODO(TLS1.3): We're going to need a new custom extension mechanism
* for TLS1.3, so that custom extensions can specify which of the
* multiple message they wish to add themselves to.
*/
addcustom = 1;
}
if (addcustom && !custom_ext_add(s, s->server, pkt, &tmpal)) {
SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
goto err;
}
for (i = 0, thisexd = ext_defs; i < OSSL_NELEM(ext_defs); i++, thisexd++) {
int (*construct)(SSL *s, WPACKET *pkt, unsigned int context, X509 *x,
size_t chainidx, int *al);
/* Skip if not relevant for our context */
if ((thisexd->context & context) == 0)
continue;
construct = s->server ? thisexd->construct_stoc
: thisexd->construct_ctos;
/* Check if this extension is defined for our protocol. If not, skip */
if ((SSL_IS_DTLS(s)
&& (thisexd->context & EXT_TLS_IMPLEMENTATION_ONLY)
!= 0)
|| (s->version == SSL3_VERSION
&& (thisexd->context & EXT_SSL3_ALLOWED) == 0)
|| (SSL_IS_TLS13(s)
&& (thisexd->context & EXT_TLS1_2_AND_BELOW_ONLY)
!= 0)
|| (!SSL_IS_TLS13(s)
&& (thisexd->context & EXT_TLS1_3_ONLY) != 0
&& (context & EXT_CLIENT_HELLO) == 0)
|| ((thisexd->context & EXT_TLS1_3_ONLY) != 0
&& (context & EXT_CLIENT_HELLO) != 0
&& (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION))
|| construct == NULL)
continue;
if (!construct(s, pkt, context, x, chainidx, &tmpal))
goto err;
}
if (!WPACKET_close(pkt)) {
SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
goto err;
}
return 1;
err:
*al = tmpal;
return 0;
}
/*
* Built in extension finalisation and initialisation functions. All initialise
* or finalise the associated extension type for the given |context|. For
* finalisers |sent| is set to 1 if we saw the extension during parsing, and 0
* otherwise. These functions return 1 on success or 0 on failure. In the event
* of a failure then |*al| is populated with a suitable error code.
*/
static int final_renegotiate(SSL *s, unsigned int context, int sent,
int *al)
{
if (!s->server) {
/*
* Check if we can connect to a server that doesn't support safe
* renegotiation
*/
if (!(s->options & SSL_OP_LEGACY_SERVER_CONNECT)
&& !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)
&& !sent) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_FINAL_RENEGOTIATE,
SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
return 0;
}
return 1;
}
/* Need RI if renegotiating */
if (s->renegotiate
&& !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)
&& !sent) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_FINAL_RENEGOTIATE,
SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
return 0;
}
return 1;
}
static int init_server_name(SSL *s, unsigned int context)
{
if (s->server)
s->servername_done = 0;
return 1;
}
static int final_server_name(SSL *s, unsigned int context, int sent,
int *al)
{
int ret = SSL_TLSEXT_ERR_NOACK;
int altmp = SSL_AD_UNRECOGNIZED_NAME;
if (s->ctx != NULL && s->ctx->ext.servername_cb != 0)
ret = s->ctx->ext.servername_cb(s, &altmp,
s->ctx->ext.servername_arg);
else if (s->session_ctx != NULL
&& s->session_ctx->ext.servername_cb != 0)
ret = s->session_ctx->ext.servername_cb(s, &altmp,
s->session_ctx->ext.servername_arg);
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
*al = altmp;
return 0;
case SSL_TLSEXT_ERR_ALERT_WARNING:
*al = altmp;
return 1;
case SSL_TLSEXT_ERR_NOACK:
s->servername_done = 0;
return 1;
default:
return 1;
}
}
#ifndef OPENSSL_NO_EC
static int final_ec_pt_formats(SSL *s, unsigned int context, int sent,
int *al)
{
unsigned long alg_k, alg_a;
if (s->server)
return 1;
alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
alg_a = s->s3->tmp.new_cipher->algorithm_auth;
/*
* 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.
*/
if (s->ext.ecpointformats != NULL
&& s->ext.ecpointformats_len > 0
&& s->session->ext.ecpointformats != NULL
&& s->session->ext.ecpointformats_len > 0
&& ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))) {
/* we are using an ECC cipher */
size_t i;
unsigned char *list = s->session->ext.ecpointformats;
for (i = 0; i < s->session->ext.ecpointformats_len; i++) {
if (*list++ == TLSEXT_ECPOINTFORMAT_uncompressed)
break;
}
if (i == s->session->ext.ecpointformats_len) {
SSLerr(SSL_F_FINAL_EC_PT_FORMATS,
SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
return 0;
}
}
return 1;
}
#endif
static int init_session_ticket(SSL *s, unsigned int context)
{
if (!s->server)
s->ext.ticket_expected = 0;
return 1;
}
#ifndef OPENSSL_NO_OCSP
static int init_status_request(SSL *s, unsigned int context)
{
if (s->server) {
s->ext.status_type = TLSEXT_STATUSTYPE_nothing;
} else {
/*
* Ensure we get sensible values passed to tlsext_status_cb in the event
* that we don't receive a status message
*/
OPENSSL_free(s->ext.ocsp.resp);
s->ext.ocsp.resp = NULL;
s->ext.ocsp.resp_len = 0;
}
return 1;
}
#endif
#ifndef OPENSSL_NO_NEXTPROTONEG
static int init_npn(SSL *s, unsigned int context)
{
s->s3->npn_seen = 0;
return 1;
}
#endif
static int init_alpn(SSL *s, unsigned int context)
{
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = NULL;
s->s3->alpn_selected_len = 0;
if (s->server) {
OPENSSL_free(s->s3->alpn_proposed);
s->s3->alpn_proposed = NULL;
s->s3->alpn_proposed_len = 0;
}
return 1;
}
static int final_alpn(SSL *s, unsigned int context, int sent, int *al)
{
const unsigned char *selected = NULL;
unsigned char selected_len = 0;
if (!s->server)
return 1;
if (s->ctx->ext.alpn_select_cb != NULL && s->s3->alpn_proposed != NULL) {
int r = s->ctx->ext.alpn_select_cb(s, &selected, &selected_len,
s->s3->alpn_proposed,
(unsigned int)s->s3->alpn_proposed_len,
s->ctx->ext.alpn_select_cb_arg);
if (r == SSL_TLSEXT_ERR_OK) {
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = OPENSSL_memdup(selected, selected_len);
if (s->s3->alpn_selected == NULL) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
s->s3->alpn_selected_len = selected_len;
#ifndef OPENSSL_NO_NEXTPROTONEG
/* ALPN takes precedence over NPN. */
s->s3->npn_seen = 0;
#endif
} else {
*al = SSL_AD_NO_APPLICATION_PROTOCOL;
return 0;
}
}
return 1;
}
static int init_sig_algs(SSL *s, unsigned int context)
{
/* Clear any signature algorithms extension received */
OPENSSL_free(s->s3->tmp.peer_sigalgs);
s->s3->tmp.peer_sigalgs = NULL;
return 1;
}
#ifndef OPENSSL_NO_SRP
static int init_srp(SSL *s, unsigned int context)
{
OPENSSL_free(s->srp_ctx.login);
s->srp_ctx.login = NULL;
return 1;
}
#endif
static int init_etm(SSL *s, unsigned int context)
{
s->ext.use_etm = 0;
return 1;
}
static int init_ems(SSL *s, unsigned int context)
{
if (!s->server)
s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
return 1;
}
static int final_ems(SSL *s, unsigned int context, int sent, int *al)
{
if (!s->server && 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_FINAL_EMS, SSL_R_INCONSISTENT_EXTMS);
return 0;
}
}
return 1;
}
#ifndef OPENSSL_NO_SRTP
static int init_srtp(SSL *s, unsigned int context)
{
if (s->server)
s->srtp_profile = NULL;
return 1;
}
#endif
static int final_sig_algs(SSL *s, unsigned int context, int sent, int *al)
{
if (!sent && SSL_IS_TLS13(s)) {
*al = TLS13_AD_MISSING_EXTENSION;
SSLerr(SSL_F_FINAL_SIG_ALGS, SSL_R_MISSING_SIGALGS_EXTENSION);
return 0;
}
return 1;
}
#ifndef OPENSSL_NO_EC
static int final_key_share(SSL *s, unsigned int context, int sent, int *al)
{
if (!SSL_IS_TLS13(s))
return 1;
/*
* If
* we are a client
* AND
* we have no key_share
* AND
* (we are not resuming
* OR the kex_mode doesn't allow non key_share resumes)
* THEN
* fail;
*/
if (!s->server
&& !sent
&& (!s->hit
|| (s->ext.psk_kex_mode & TLSEXT_KEX_MODE_FLAG_KE) == 0)) {
/* Nothing left we can do - just fail */
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_FINAL_KEY_SHARE, SSL_R_NO_SUITABLE_KEY_SHARE);
return 0;
}
/*
* If
* we are a server
* AND
* we have no key_share
* THEN
* If
* we didn't already send a HelloRetryRequest
* AND
* the client sent a key_share extension
* AND
* (we are not resuming
* OR the kex_mode allows key_share resumes)
* AND
* a shared group exists
* THEN
* send a HelloRetryRequest
* ELSE If
* we are not resuming
* OR
* the kex_mode doesn't allow non key_share resumes
* THEN
* fail;
*/
if (s->server && s->s3->peer_tmp == NULL) {
/* No suitable share */
if (s->hello_retry_request == 0 && sent
&& (!s->hit
|| (s->ext.psk_kex_mode & TLSEXT_KEX_MODE_FLAG_KE_DHE)
!= 0)) {
const unsigned char *pcurves, *pcurvestmp, *clntcurves;
size_t num_curves, clnt_num_curves, i;
unsigned int group_id = 0;
/* Check if a shared group exists */
/* Get the clients list of supported groups. */
if (!tls1_get_curvelist(s, 1, &clntcurves, &clnt_num_curves)) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_FINAL_KEY_SHARE, ERR_R_INTERNAL_ERROR);
return 0;
}
/* Get our list of available groups */
if (!tls1_get_curvelist(s, 0, &pcurves, &num_curves)) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_FINAL_KEY_SHARE, ERR_R_INTERNAL_ERROR);
return 0;
}
/* Find the first group we allow that is also in client's list */
for (i = 0, pcurvestmp = pcurves; i < num_curves;
i++, pcurvestmp += 2) {
group_id = bytestogroup(pcurvestmp);
if (check_in_list(s, group_id, clntcurves, clnt_num_curves, 1))
break;
}
if (i < num_curves) {
/* A shared group exists so send a HelloRetryRequest */
s->s3->group_id = group_id;
s->hello_retry_request = 1;
return 1;
}
}
if (!s->hit
|| (s->ext.psk_kex_mode & TLSEXT_KEX_MODE_FLAG_KE) == 0) {
/* Nothing left we can do - just fail */
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_FINAL_KEY_SHARE, SSL_R_NO_SUITABLE_KEY_SHARE);
return 0;
}
}
/* We have a key_share so don't send any more HelloRetryRequest messages */
if (s->server)
s->hello_retry_request = 0;
/*
* For a client side resumption with no key_share we need to generate
* the handshake secret (otherwise this is done during key_share
* processing).
*/
if (!sent && !s->server && !tls13_generate_handshake_secret(s, NULL, 0)) {
*al = SSL_AD_INTERNAL_ERROR;
SSLerr(SSL_F_FINAL_KEY_SHARE, ERR_R_INTERNAL_ERROR);
return 0;
}
return 1;
}
#endif
static int init_psk_kex_modes(SSL *s, unsigned int context)
{
s->ext.psk_kex_mode = TLSEXT_KEX_MODE_FLAG_NONE;
return 1;
}
int tls_psk_do_binder(SSL *s, const EVP_MD *md, const unsigned char *msgstart,
size_t binderoffset, const unsigned char *binderin,
unsigned char *binderout,
SSL_SESSION *sess, int sign)
{
EVP_PKEY *mackey = NULL;
EVP_MD_CTX *mctx = NULL;
unsigned char hash[EVP_MAX_MD_SIZE], binderkey[EVP_MAX_MD_SIZE];
unsigned char finishedkey[EVP_MAX_MD_SIZE], tmpbinder[EVP_MAX_MD_SIZE];
const char resumption_label[] = "resumption psk binder key";
size_t bindersize, hashsize = EVP_MD_size(md);
int ret = -1;
/* Generate the early_secret */
if (!tls13_generate_secret(s, md, NULL, sess->master_key,
sess->master_key_length,
(unsigned char *)&s->early_secret)) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
/*
* Create the handshake hash for the binder key...the messages so far are
* empty!
*/
mctx = EVP_MD_CTX_new();
if (mctx == NULL
|| EVP_DigestInit_ex(mctx, md, NULL) <= 0
|| EVP_DigestFinal_ex(mctx, hash, NULL) <= 0) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
/* Generate the binder key */
if (!tls13_hkdf_expand(s, md, s->early_secret,
(unsigned char *)resumption_label,
sizeof(resumption_label) - 1, hash, binderkey,
hashsize)) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
/* Generate the finished key */
if (!tls13_derive_finishedkey(s, md, binderkey, finishedkey, hashsize)) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
if (EVP_DigestInit_ex(mctx, md, NULL) <= 0) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
/*
* Get a hash of the ClientHello up to the start of the binders. If we are
* following a HelloRetryRequest then this includes the hash of the first
* ClientHello and the HelloRetryRequest itself.
*/
if (s->hello_retry_request) {
size_t hdatalen;
void *hdata;
hdatalen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
if (hdatalen <= 0) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, SSL_R_BAD_HANDSHAKE_LENGTH);
goto err;
}
/*
* For servers the handshake buffer data will include the second
* ClientHello - which we don't want - so we need to take that bit off.
*/
if (s->server) {
PACKET hashprefix, msg;
/* Find how many bytes are left after the first two messages */
if (!PACKET_buf_init(&hashprefix, hdata, hdatalen)
|| !PACKET_forward(&hashprefix, 1)
|| !PACKET_get_length_prefixed_3(&hashprefix, &msg)
|| !PACKET_forward(&hashprefix, 1)
|| !PACKET_get_length_prefixed_3(&hashprefix, &msg)) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
hdatalen -= PACKET_remaining(&hashprefix);
}
if (EVP_DigestUpdate(mctx, hdata, hdatalen) <= 0) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
}
if (EVP_DigestUpdate(mctx, msgstart, binderoffset) <= 0
|| EVP_DigestFinal_ex(mctx, hash, NULL) <= 0) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
mackey = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL, finishedkey, hashsize);
if (mackey == NULL) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
if (!sign)
binderout = tmpbinder;
bindersize = hashsize;
if (EVP_DigestSignInit(mctx, NULL, md, NULL, mackey) <= 0
|| EVP_DigestSignUpdate(mctx, hash, hashsize) <= 0
|| EVP_DigestSignFinal(mctx, binderout, &bindersize) <= 0
|| bindersize != hashsize) {
SSLerr(SSL_F_TLS_PSK_DO_BINDER, ERR_R_INTERNAL_ERROR);
goto err;
}
if (sign) {
ret = 1;
} else {
/* HMAC keys can't do EVP_DigestVerify* - use CRYPTO_memcmp instead */
ret = (CRYPTO_memcmp(binderin, binderout, hashsize) == 0);
}
err:
OPENSSL_cleanse(binderkey, sizeof(binderkey));
OPENSSL_cleanse(finishedkey, sizeof(finishedkey));
EVP_PKEY_free(mackey);
EVP_MD_CTX_free(mctx);
return ret;
}
static int final_early_data(SSL *s, unsigned int context, int sent, int *al)
{
if (!s->server || !sent)
return 1;
if (s->max_early_data == 0
|| !s->hit
|| s->session->ext.tick_identity != 0
|| s->early_data_state != SSL_EARLY_DATA_ACCEPTING
|| !s->ext.early_data_ok
|| s->hello_retry_request
|| s->s3->alpn_selected_len != s->session->ext.alpn_selected_len
|| (s->s3->alpn_selected_len > 0
&& memcmp(s->s3->alpn_selected, s->session->ext.alpn_selected,
s->s3->alpn_selected_len) != 0)) {
s->ext.early_data = SSL_EARLY_DATA_REJECTED;
} else {
s->ext.early_data = SSL_EARLY_DATA_ACCEPTED;
if (!tls13_change_cipher_state(s,
SSL3_CC_EARLY | SSL3_CHANGE_CIPHER_SERVER_READ)) {
*al = SSL_AD_INTERNAL_ERROR;
return 0;
}
}
return 1;
}
