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extensions.c
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extensions.c
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/*
* Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (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 "internal/nelem.h"
#include "internal/cryptlib.h"
#include "../ssl_local.h"
#include "statem_local.h"
#include "internal/cryptlib.h"
static int final_renegotiate(SSL *s, unsigned int context, int sent);
static int init_server_name(SSL *s, unsigned int context);
static int final_server_name(SSL *s, unsigned int context, int sent);
#ifndef OPENSSL_NO_EC
static int final_ec_pt_formats(SSL *s, unsigned int context, int sent);
#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);
static int init_sig_algs_cert(SSL *s, unsigned int context);
static int init_sig_algs(SSL *s, unsigned int context);
static int init_certificate_authorities(SSL *s, unsigned int context);
static EXT_RETURN tls_construct_certificate_authorities(SSL *s, WPACKET *pkt,
unsigned int context,
X509 *x,
size_t chainidx);
static int tls_parse_certificate_authorities(SSL *s, PACKET *pkt,
unsigned int context, X509 *x,
size_t chainidx);
#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);
static int init_psk_kex_modes(SSL *s, unsigned int context);
static int final_key_share(SSL *s, unsigned int context, int sent);
#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);
static int final_early_data(SSL *s, unsigned int context, int sent);
static int final_maxfragmentlen(SSL *s, unsigned int context, int sent);
static int init_post_handshake_auth(SSL *s, unsigned int context);
/* 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);
/* Parse extension send from server to client */
int (*parse_stoc)(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
size_t chainidx);
/* Construct extension sent from server to client */
EXT_RETURN (*construct_stoc)(SSL *s, WPACKET *pkt, unsigned int context,
X509 *x, size_t chainidx);
/* Construct extension sent from client to server */
EXT_RETURN (*construct_ctos)(SSL *s, WPACKET *pkt, unsigned int context,
X509 *x, size_t chainidx);
/*
* 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);
} 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_local.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
*
* NOTE: WebSphere Application Server 7+ cannot handle empty extensions at
* the end, keep these extensions before signature_algorithm.
*/
#define INVALID_EXTENSION { 0x10000, 0, NULL, NULL, NULL, NULL, NULL, NULL }
static const EXTENSION_DEFINITION ext_defs[] = {
{
TLSEXT_TYPE_renegotiate,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_SSL3_ALLOWED | SSL_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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_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
},
{
TLSEXT_TYPE_max_fragment_length,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS,
NULL, tls_parse_ctos_maxfragmentlen, tls_parse_stoc_maxfragmentlen,
tls_construct_stoc_maxfragmentlen, tls_construct_ctos_maxfragmentlen,
final_maxfragmentlen
},
#ifndef OPENSSL_NO_SRP
{
TLSEXT_TYPE_srp,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_AND_BELOW_ONLY,
init_srp, tls_parse_ctos_srp, NULL, NULL, tls_construct_ctos_srp, NULL
},
#else
INVALID_EXTENSION,
#endif
#ifndef OPENSSL_NO_EC
{
TLSEXT_TYPE_ec_point_formats,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_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
},
#else
INVALID_EXTENSION,
#endif
#if !defined(OPENSSL_NO_EC) || !defined(OPENSSL_NO_DH)
{
/*
* "supported_groups" is spread across several specifications.
* It was originally specified as "elliptic_curves" in RFC 4492,
* and broadened to include named FFDH groups by RFC 7919.
* Both RFCs 4492 and 7919 do not include a provision for the server
* to indicate to the client the complete list of groups supported
* by the server, with the server instead just indicating the
* selected group for this connection in the ServerKeyExchange
* message. TLS 1.3 adds a scheme for the server to indicate
* to the client its list of supported groups in the
* EncryptedExtensions message, but none of the relevant
* specifications permit sending supported_groups in the ServerHello.
* Nonetheless (possibly due to the close proximity to the
* "ec_point_formats" extension, which is allowed in the ServerHello),
* there are several servers that send this extension in the
* ServerHello anyway. Up to and including the 1.1.0 release,
* we did not check for the presence of nonpermitted extensions,
* so to avoid a regression, we must permit this extension in the
* TLS 1.2 ServerHello as well.
*
* Note that there is no tls_parse_stoc_supported_groups function,
* so we do not perform any additional parsing, validation, or
* processing on the server's group list -- this is just a minimal
* change to preserve compatibility with these misbehaving servers.
*/
TLSEXT_TYPE_supported_groups,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| SSL_EXT_TLS1_2_SERVER_HELLO,
NULL, tls_parse_ctos_supported_groups, NULL,
tls_construct_stoc_supported_groups,
tls_construct_ctos_supported_groups, NULL
},
#else
INVALID_EXTENSION,
#endif
{
TLSEXT_TYPE_session_ticket,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_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
},
#ifndef OPENSSL_NO_OCSP
{
TLSEXT_TYPE_status_request,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_3_CERTIFICATE | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST,
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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS | SSL_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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_2_AND_BELOW_ONLY,
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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_3_CERTIFICATE | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST,
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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_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_signature_algorithms_cert,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST,
init_sig_algs_cert, tls_parse_ctos_sig_algs_cert,
tls_parse_ctos_sig_algs_cert,
/* We do not generate signature_algorithms_cert at present. */
NULL, NULL, NULL
},
{
TLSEXT_TYPE_post_handshake_auth,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_ONLY,
init_post_handshake_auth,
tls_parse_ctos_post_handshake_auth, NULL,
NULL, tls_construct_ctos_post_handshake_auth,
NULL,
},
{
TLSEXT_TYPE_signature_algorithms,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST,
init_sig_algs, tls_parse_ctos_sig_algs,
tls_parse_ctos_sig_algs, tls_construct_ctos_sig_algs,
tls_construct_ctos_sig_algs, final_sig_algs
},
{
TLSEXT_TYPE_supported_versions,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_SERVER_HELLO
| SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST | SSL_EXT_TLS_IMPLEMENTATION_ONLY,
NULL,
/* Processed inline as part of version selection */
NULL, tls_parse_stoc_supported_versions,
tls_construct_stoc_supported_versions,
tls_construct_ctos_supported_versions, NULL
},
{
TLSEXT_TYPE_psk_kex_modes,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS_IMPLEMENTATION_ONLY
| SSL_EXT_TLS1_3_ONLY,
init_psk_kex_modes, tls_parse_ctos_psk_kex_modes, NULL, NULL,
tls_construct_ctos_psk_kex_modes, NULL
},
{
/*
* Must be in this list after supported_groups. We need that to have
* been parsed before we do this one.
*/
TLSEXT_TYPE_key_share,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_SERVER_HELLO
| SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST | SSL_EXT_TLS_IMPLEMENTATION_ONLY
| SSL_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
},
{
/* Must be after key_share */
TLSEXT_TYPE_cookie,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST
| SSL_EXT_TLS_IMPLEMENTATION_ONLY | SSL_EXT_TLS1_3_ONLY,
NULL, tls_parse_ctos_cookie, tls_parse_stoc_cookie,
tls_construct_stoc_cookie, tls_construct_ctos_cookie, NULL
},
{
/*
* Special unsolicited ServerHello extension only used when
* SSL_OP_CRYPTOPRO_TLSEXT_BUG is set. We allow it in a ClientHello but
* ignore it.
*/
TLSEXT_TYPE_cryptopro_bug,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO
| SSL_EXT_TLS1_2_AND_BELOW_ONLY,
NULL, NULL, NULL, tls_construct_stoc_cryptopro_bug, NULL, NULL
},
{
TLSEXT_TYPE_early_data,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| SSL_EXT_TLS1_3_NEW_SESSION_TICKET | SSL_EXT_TLS1_3_ONLY,
NULL, tls_parse_ctos_early_data, tls_parse_stoc_early_data,
tls_construct_stoc_early_data, tls_construct_ctos_early_data,
final_early_data
},
{
TLSEXT_TYPE_certificate_authorities,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_CERTIFICATE_REQUEST
| SSL_EXT_TLS1_3_ONLY,
init_certificate_authorities,
tls_parse_certificate_authorities, tls_parse_certificate_authorities,
tls_construct_certificate_authorities,
tls_construct_certificate_authorities, NULL,
},
{
/* Must be immediately before pre_shared_key */
TLSEXT_TYPE_padding,
SSL_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,
SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_3_SERVER_HELLO
| SSL_EXT_TLS_IMPLEMENTATION_ONLY | SSL_EXT_TLS1_3_ONLY,
NULL, tls_parse_ctos_psk, tls_parse_stoc_psk, tls_construct_stoc_psk,
tls_construct_ctos_psk, NULL
}
};
/* Check whether an extension's context matches the current context */
static int validate_context(SSL *s, unsigned int extctx, unsigned int thisctx)
{
/* Check we're allowed to use this extension in this context */
if ((thisctx & extctx) == 0)
return 0;
if (SSL_IS_DTLS(s)) {
if ((extctx & SSL_EXT_TLS_ONLY) != 0)
return 0;
} else if ((extctx & SSL_EXT_DTLS_ONLY) != 0) {
return 0;
}
return 1;
}
int tls_validate_all_contexts(SSL *s, unsigned int thisctx, RAW_EXTENSION *exts)
{
size_t i, num_exts, builtin_num = OSSL_NELEM(ext_defs), offset;
RAW_EXTENSION *thisext;
unsigned int context;
ENDPOINT role = ENDPOINT_BOTH;
if ((thisctx & SSL_EXT_CLIENT_HELLO) != 0)
role = ENDPOINT_SERVER;
else if ((thisctx & SSL_EXT_TLS1_2_SERVER_HELLO) != 0)
role = ENDPOINT_CLIENT;
/* Calculate the number of extensions in the extensions list */
num_exts = builtin_num + s->cert->custext.meths_count;
for (thisext = exts, i = 0; i < num_exts; i++, thisext++) {
if (!thisext->present)
continue;
if (i < builtin_num) {
context = ext_defs[i].context;
} else {
custom_ext_method *meth = NULL;
meth = custom_ext_find(&s->cert->custext, role, thisext->type,
&offset);
if (!ossl_assert(meth != NULL))
return 0;
context = meth->context;
}
if (!validate_context(s, context, thisctx))
return 0;
}
return 1;
}
/*
* 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
* the definition for the extension we found.
*/
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) {
if (!validate_context(s, thisext->context, context))
return 0;
*found = &rawexlist[i];
return 1;
}
}
/* Check the custom extensions */
if (meths != NULL) {
size_t offset = 0;
ENDPOINT role = ENDPOINT_BOTH;
custom_ext_method *meth = NULL;
if ((context & SSL_EXT_CLIENT_HELLO) != 0)
role = ENDPOINT_SERVER;
else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0)
role = ENDPOINT_CLIENT;
meth = custom_ext_find(meths, role, type, &offset);
if (meth != NULL) {
if (!validate_context(s, meth->context, context))
return 0;
*found = &rawexlist[offset + builtin_num];
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
*/
int extension_is_relevant(SSL *s, unsigned int extctx, unsigned int thisctx)
{
int is_tls13;
/*
* For HRR we haven't selected the version yet but we know it will be
* TLSv1.3
*/
if ((thisctx & SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST) != 0)
is_tls13 = 1;
else
is_tls13 = SSL_IS_TLS13(s);
if ((SSL_IS_DTLS(s)
&& (extctx & SSL_EXT_TLS_IMPLEMENTATION_ONLY) != 0)
|| (s->version == SSL3_VERSION
&& (extctx & SSL_EXT_SSL3_ALLOWED) == 0)
/*
* Note that SSL_IS_TLS13() means "TLS 1.3 has been negotiated",
* which is never true when generating the ClientHello.
* However, version negotiation *has* occurred by the time the
* ClientHello extensions are being parsed.
* Be careful to allow TLS 1.3-only extensions when generating
* the ClientHello.
*/
|| (is_tls13 && (extctx & SSL_EXT_TLS1_2_AND_BELOW_ONLY) != 0)
|| (!is_tls13 && (extctx & SSL_EXT_TLS1_3_ONLY) != 0
&& (thisctx & SSL_EXT_CLIENT_HELLO) == 0)
|| (s->server && !is_tls13 && (extctx & SSL_EXT_TLS1_3_ONLY) != 0)
|| (s->hit && (extctx & SSL_EXT_IGNORE_ON_RESUMPTION) != 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. 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 if |init| is nonzero (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, size_t *len, int init)
{
PACKET extensions = *packet;
size_t i = 0;
size_t num_exts;
custom_ext_methods *exts = &s->cert->custext;
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 & SSL_EXT_CLIENT_HELLO) != 0)
custom_ext_init(&s->cert->custext);
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) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_COLLECT_EXTENSIONS,
ERR_R_MALLOC_FAILURE);
return 0;
}
i = 0;
while (PACKET_remaining(&extensions) > 0) {
unsigned int type, idx;
PACKET extension;
RAW_EXTENSION *thisex;
if (!PACKET_get_net_2(&extensions, &type) ||
!PACKET_get_length_prefixed_2(&extensions, &extension)) {
SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_TLS_COLLECT_EXTENSIONS,
SSL_R_BAD_EXTENSION);
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 & SSL_EXT_CLIENT_HELLO) != 0
&& PACKET_remaining(&extensions) != 0)) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_COLLECT_EXTENSIONS,
SSL_R_BAD_EXTENSION);
goto err;
}
idx = thisex - raw_extensions;
/*-
* Check that we requested this extension (if appropriate). Requests can
* be sent in the ClientHello and CertificateRequest. Unsolicited
* extensions can be sent in the NewSessionTicket. We only do this for
* the built-in extensions. Custom extensions have a different but
* similar check elsewhere.
* Special cases:
* - The HRR cookie extension is unsolicited
* - The renegotiate extension is unsolicited (the client signals
* support via an SCSV)
* - The signed_certificate_timestamp extension can be provided by a
* custom extension or by the built-in version. We let the extension
* itself handle unsolicited response checks.
*/
if (idx < OSSL_NELEM(ext_defs)
&& (context & (SSL_EXT_CLIENT_HELLO
| SSL_EXT_TLS1_3_CERTIFICATE_REQUEST
| SSL_EXT_TLS1_3_NEW_SESSION_TICKET)) == 0
&& type != TLSEXT_TYPE_cookie
&& type != TLSEXT_TYPE_renegotiate
&& type != TLSEXT_TYPE_signed_certificate_timestamp
&& (s->ext.extflags[idx] & SSL_EXT_FLAG_SENT) == 0
#ifndef OPENSSL_NO_GOST
&& !((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0
&& type == TLSEXT_TYPE_cryptopro_bug)
#endif
) {
SSLfatal(s, SSL_AD_UNSUPPORTED_EXTENSION,
SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_UNSOLICITED_EXTENSION);
goto err;
}
if (thisex != NULL) {
thisex->data = extension;
thisex->present = 1;
thisex->type = type;
thisex->received_order = i++;
if (s->ext.debug_cb)
s->ext.debug_cb(s, !s->server, thisex->type,
PACKET_data(&thisex->data),
PACKET_remaining(&thisex->data),
s->ext.debug_arg);
}
}
if (init) {
/*
* 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)) {
/* SSLfatal() already called */
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. 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)
{
RAW_EXTENSION *currext = &exts[idx];
int (*parser)(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
size_t chainidx) = NULL;
/* Skip if the extension is not present */
if (!currext->present)
return 1;
/* 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);
/*
* If the parser is NULL we fall through to the custom extension
* processing
*/
}
/* Parse custom extensions */
return custom_ext_parse(s, context, currext->type,
PACKET_data(&currext->data),
PACKET_remaining(&currext->data),
x, chainidx);
}
/*
* Parse all remaining extensions that have not yet been parsed. Also calls the
* finalisation for all extensions at the end if |fin| is nonzero, 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.
*/
int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts, X509 *x,
size_t chainidx, int fin)
{
size_t i, numexts = OSSL_NELEM(ext_defs);
const EXTENSION_DEFINITION *thisexd;
/* Calculate the number of extensions in the extensions list */
numexts += s->cert->custext.meths_count;
/* Parse each extension in turn */
for (i = 0; i < numexts; i++) {
if (!tls_parse_extension(s, i, context, exts, x, chainidx)) {
/* SSLfatal() already called */
return 0;
}
}
if (fin) {
/*
* 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)) {
/* SSLfatal() already called */
return 0;
}
}
}
return 1;
}
int should_add_extension(SSL *s, unsigned int extctx, unsigned int thisctx,
int max_version)
{
/* Skip if not relevant for our context */
if ((extctx & thisctx) == 0)
return 0;
/* Check if this extension is defined for our protocol. If not, skip */
if (!extension_is_relevant(s, extctx, thisctx)
|| ((extctx & SSL_EXT_TLS1_3_ONLY) != 0
&& (thisctx & SSL_EXT_CLIENT_HELLO) != 0
&& (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION)))
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. 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)
{
size_t i;
int min_version, max_version = 0, reason;
const EXTENSION_DEFINITION *thisexd;
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
* (for non-TLSv1.3).
*/
|| ((context &
(SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0
&& !WPACKET_set_flags(pkt,
WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH))) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_EXTENSIONS,
ERR_R_INTERNAL_ERROR);
return 0;
}
if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
reason = ssl_get_min_max_version(s, &min_version, &max_version, NULL);
if (reason != 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_EXTENSIONS,
reason);
return 0;
}
}
/* Add custom extensions first */
if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
/* On the server side with initialise during ClientHello parsing */
custom_ext_init(&s->cert->custext);
}
if (!custom_ext_add(s, context, pkt, x, chainidx, max_version)) {
/* SSLfatal() already called */
return 0;
}
for (i = 0, thisexd = ext_defs; i < OSSL_NELEM(ext_defs); i++, thisexd++) {
EXT_RETURN (*construct)(SSL *s, WPACKET *pkt, unsigned int context,
X509 *x, size_t chainidx);
EXT_RETURN ret;
/* Skip if not relevant for our context */
if (!should_add_extension(s, thisexd->context, context, max_version))
continue;
construct = s->server ? thisexd->construct_stoc
: thisexd->construct_ctos;
if (construct == NULL)
continue;
ret = construct(s, pkt, context, x, chainidx);
if (ret == EXT_RETURN_FAIL) {
/* SSLfatal() already called */
return 0;
}
if (ret == EXT_RETURN_SENT
&& (context & (SSL_EXT_CLIENT_HELLO
| SSL_EXT_TLS1_3_CERTIFICATE_REQUEST
| SSL_EXT_TLS1_3_NEW_SESSION_TICKET)) != 0)
s->ext.extflags[i] |= SSL_EXT_FLAG_SENT;
}
if (!WPACKET_close(pkt)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_CONSTRUCT_EXTENSIONS,
ERR_R_INTERNAL_ERROR);
return 0;
}
return 1;
}
/*
* 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.
*/
static int final_renegotiate(SSL *s, unsigned int context, int sent)
{
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) {
SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, 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) {
SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, 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;
OPENSSL_free(s->ext.hostname);
s->ext.hostname = NULL;
}
return 1;
}
static int final_server_name(SSL *s, unsigned int context, int sent)
{
int ret = SSL_TLSEXT_ERR_NOACK;
int altmp = SSL_AD_UNRECOGNIZED_NAME;
int was_ticket = (SSL_get_options(s) & SSL_OP_NO_TICKET) == 0;
if (!ossl_assert(s->ctx != NULL) || !ossl_assert(s->session_ctx != NULL)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_SERVER_NAME,
ERR_R_INTERNAL_ERROR);
return 0;
}
if (s->ctx->ext.servername_cb != NULL)
ret = s->ctx->ext.servername_cb(s, &altmp,
s->ctx->ext.servername_arg);
else if (s->session_ctx->ext.servername_cb != NULL)
ret = s->session_ctx->ext.servername_cb(s, &altmp,
s->session_ctx->ext.servername_arg);
/*
* For servers, propagate the SNI hostname from the temporary
* storage in the SSL to the persistent SSL_SESSION, now that we
* know we accepted it.
* Clients make this copy when parsing the server's response to
* the extension, which is when they find out that the negotiation
* was successful.
*/
if (s->server) {
/* TODO(OpenSSL1.2) revisit !sent case */
if (sent && ret == SSL_TLSEXT_ERR_OK && !s->hit) {
/* Only store the hostname in the session if we accepted it. */
OPENSSL_free(s->session->ext.hostname);
s->session->ext.hostname = OPENSSL_strdup(s->ext.hostname);
if (s->session->ext.hostname == NULL && s->ext.hostname != NULL) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_SERVER_NAME,
ERR_R_INTERNAL_ERROR);
}
}
}
/*
* If we switched contexts (whether here or in the client_hello callback),
* move the sess_accept increment from the session_ctx to the new
* context, to avoid the confusing situation of having sess_accept_good
* exceed sess_accept (zero) for the new context.
*/
if (SSL_IS_FIRST_HANDSHAKE(s) && s->ctx != s->session_ctx) {
tsan_counter(&s->ctx->stats.sess_accept);
tsan_decr(&s->session_ctx->stats.sess_accept);
}
/*
* If we're expecting to send a ticket, and tickets were previously enabled,
* and now tickets are disabled, then turn off expected ticket.
* Also, if this is not a resumption, create a new session ID
*/
if (ret == SSL_TLSEXT_ERR_OK && s->ext.ticket_expected
&& was_ticket && (SSL_get_options(s) & SSL_OP_NO_TICKET) != 0) {
s->ext.ticket_expected = 0;
if (!s->hit) {
SSL_SESSION* ss = SSL_get_session(s);
if (ss != NULL) {
OPENSSL_free(ss->ext.tick);
ss->ext.tick = NULL;
ss->ext.ticklen = 0;
ss->ext.tick_lifetime_hint = 0;
ss->ext.tick_age_add = 0;
if (!ssl_generate_session_id(s, ss)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_SERVER_NAME,
ERR_R_INTERNAL_ERROR);
return 0;
}
} else {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_SERVER_NAME,
ERR_R_INTERNAL_ERROR);
return 0;
}