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2a53855110
openssl/ssl/statem/extensions.c
Benjamin Kaduk 2a53855110 Fix a race condition in SNI handling 
As was done for ciphers, supported groups, and EC point formats in
https://github.com/openssl/openssl/pull/9162, only write the negotiated
SNI hostname value to the session object when not resuming, even for
TLS 1.3 resumptions.  Otherwise, when using a stateful session cache
(as is done by default when 0-RTT data is enabled), we can have multiple
SSLs active using the same in-memory session object, which leads to
double-frees and similar race conditions in the SNI handler prior
to this commit.

Fortunately, since draft-ietf-tls-tls13-22, there is no requirement
that the SNI hostname be preserved across TLS 1.3 resumption, and thus
not a need to continually update the session object with the "current"
value (to be used when producing session tickets, so that the subsequent
resumption can be checked against the current value).  So we can just
relax the logic and only write to the session object for initial handshakes.
This still leaves us in a somewhat inconsistent state, since if the SNI value
does change across handshakes, the session object will continue to record
the initial handshake's value, even if that bears no relation to the
current handshake.  The current SSL_get_servername() implementation
prefers the value from the session if s->hit, but a more complete fix
for that and related issues is underway in
https://github.com/openssl/openssl/pull/10018; there is no need to wait
for the complete fix for SNI name handling in order to close the
race condition and avoid runtime crashes.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10441)
2019-11-21 18:09:59 -08:00

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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;
}
}
}
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
SSLfatal(s, altmp, SSL_F_FINAL_SERVER_NAME, SSL_R_CALLBACK_FAILED);
return 0;
case SSL_TLSEXT_ERR_ALERT_WARNING:
/* TLSv1.3 doesn't have warning alerts so we suppress this */
if (!SSL_IS_TLS13(s))
ssl3_send_alert(s, SSL3_AL_WARNING, 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)
{
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->ext.peer_ecpointformats != NULL
&& s->ext.peer_ecpointformats_len > 0
&& ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))) {
/* we are using an ECC cipher */
size_t i;
unsigned char *list = s->ext.peer_ecpointformats;
for (i = 0; i < s->ext.peer_ecpointformats_len; i++) {
if (*list++ == TLSEXT_ECPOINTFORMAT_uncompressed)
break;
}
if (i == s->ext.peer_ecpointformats_len) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, 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)
{
if (!s->server && !sent && s->session->ext.alpn_selected != NULL)
s->ext.early_data_ok = 0;
if (!s->server || !SSL_IS_TLS13(s))
return 1;
/*
* Call alpn_select callback if needed. Has to be done after SNI and
* cipher negotiation (HTTP/2 restricts permitted ciphers). In TLSv1.3
* we also have to do this before we decide whether to accept early_data.
* In TLSv1.3 we've already negotiated our cipher so we do this call now.
* For < TLSv1.3 we defer it until after cipher negotiation.
*
* On failure SSLfatal() already called.
*/
return tls_handle_alpn(s);
}
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;
}
static int init_sig_algs_cert(SSL *s, unsigned int context)
{
/* Clear any signature algorithms extension received */
OPENSSL_free(s->s3.tmp.peer_cert_sigalgs);
s->s3.tmp.peer_cert_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)
{
s->s3.flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
return 1;
}
static int final_ems(SSL *s, unsigned int context, int sent)
{
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)) {
SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_F_FINAL_EMS,
SSL_R_INCONSISTENT_EXTMS);
return 0;
}
}
return 1;
}
static int init_certificate_authorities(SSL *s, unsigned int context)
{
sk_X509_NAME_pop_free(s->s3.tmp.peer_ca_names, X509_NAME_free);
s->s3.tmp.peer_ca_names = NULL;
return 1;
}
static EXT_RETURN tls_construct_certificate_authorities(SSL *s, WPACKET *pkt,
unsigned int context,
X509 *x,
size_t chainidx)
{
const STACK_OF(X509_NAME) *ca_sk = get_ca_names(s);
if (ca_sk == NULL || sk_X509_NAME_num(ca_sk) == 0)
return EXT_RETURN_NOT_SENT;
if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_certificate_authorities)
|| !WPACKET_start_sub_packet_u16(pkt)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR,
SSL_F_TLS_CONSTRUCT_CERTIFICATE_AUTHORITIES,
ERR_R_INTERNAL_ERROR);
return EXT_RETURN_FAIL;
}
if (!construct_ca_names(s, ca_sk, pkt)) {
/* SSLfatal() already called */
return EXT_RETURN_FAIL;
}
if (!WPACKET_close(pkt)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR,
SSL_F_TLS_CONSTRUCT_CERTIFICATE_AUTHORITIES,
ERR_R_INTERNAL_ERROR);
return EXT_RETURN_FAIL;
}
return EXT_RETURN_SENT;
}
static int tls_parse_certificate_authorities(SSL *s, PACKET *pkt,
unsigned int context, X509 *x,
size_t chainidx)
{
if (!parse_ca_names(s, pkt))
return 0;
if (PACKET_remaining(pkt) != 0) {
SSLfatal(s, SSL_AD_DECODE_ERROR,
SSL_F_TLS_PARSE_CERTIFICATE_AUTHORITIES, SSL_R_BAD_EXTENSION);
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)
{
if (!sent && SSL_IS_TLS13(s) && !s->hit) {
SSLfatal(s, TLS13_AD_MISSING_EXTENSION, SSL_F_FINAL_SIG_ALGS,
SSL_R_MISSING_SIGALGS_EXTENSION);
return 0;
}
return 1;
}
static int final_key_share(SSL *s, unsigned int context, int sent)
{
#if !defined(OPENSSL_NO_TLS1_3)
if (!SSL_IS_TLS13(s))
return 1;
/* Nothing to do for key_share in an HRR */
if ((context & SSL_EXT_TLS1_3_HELLO_RETRY_REQUEST) != 0)
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 */
SSLfatal(s, SSL_AD_MISSING_EXTENSION, SSL_F_FINAL_KEY_SHARE,
SSL_R_NO_SUITABLE_KEY_SHARE);
return 0;
}
/*
* IF
* we are a server
* THEN
* IF
* we have a suitable key_share
* THEN
* IF
* we are stateless AND we have no cookie
* THEN
* send a HelloRetryRequest
* ELSE
* 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
* ELSE IF
* we are stateless AND we have no cookie
* THEN
* send a HelloRetryRequest
*/
if (s->server) {
if (s->s3.peer_tmp != NULL) {
/* We have a suitable key_share */
if ((s->s3.flags & TLS1_FLAGS_STATELESS) != 0
&& !s->ext.cookieok) {
if (!ossl_assert(s->hello_retry_request == SSL_HRR_NONE)) {
/*
* If we are stateless then we wouldn't know about any
* previously sent HRR - so how can this be anything other
* than 0?
*/
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_KEY_SHARE,
ERR_R_INTERNAL_ERROR);
return 0;
}
s->hello_retry_request = SSL_HRR_PENDING;
return 1;
}
} else {
/* No suitable key_share */
if (s->hello_retry_request == SSL_HRR_NONE && sent
&& (!s->hit
|| (s->ext.psk_kex_mode & TLSEXT_KEX_MODE_FLAG_KE_DHE)
!= 0)) {
const uint16_t *pgroups, *clntgroups;
size_t num_groups, clnt_num_groups, i;
unsigned int group_id = 0;
/* Check if a shared group exists */
/* Get the clients list of supported groups. */
tls1_get_peer_groups(s, &clntgroups, &clnt_num_groups);
tls1_get_supported_groups(s, &pgroups, &num_groups);
/*
* Find the first group we allow that is also in client's list
*/
for (i = 0; i < num_groups; i++) {
group_id = pgroups[i];
if (check_in_list(s, group_id, clntgroups, clnt_num_groups,
1))
break;
}
if (i < num_groups) {
/* A shared group exists so send a HelloRetryRequest */
s->s3.group_id = group_id;
s->hello_retry_request = SSL_HRR_PENDING;
return 1;
}
}
if (!s->hit
|| (s->ext.psk_kex_mode & TLSEXT_KEX_MODE_FLAG_KE) == 0) {
/* Nothing left we can do - just fail */
SSLfatal(s, sent ? SSL_AD_HANDSHAKE_FAILURE
: SSL_AD_MISSING_EXTENSION,
SSL_F_FINAL_KEY_SHARE, SSL_R_NO_SUITABLE_KEY_SHARE);
return 0;
}
if ((s->s3.flags & TLS1_FLAGS_STATELESS) != 0
&& !s->ext.cookieok) {
if (!ossl_assert(s->hello_retry_request == SSL_HRR_NONE)) {
/*
* If we are stateless then we wouldn't know about any
* previously sent HRR - so how can this be anything other
* than 0?
*/
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_KEY_SHARE,
ERR_R_INTERNAL_ERROR);
return 0;
}
s->hello_retry_request = SSL_HRR_PENDING;
return 1;
}
}
/*
* We have a key_share so don't send any more HelloRetryRequest
* messages
*/
if (s->hello_retry_request == SSL_HRR_PENDING)
s->hello_retry_request = SSL_HRR_COMPLETE;
} else {
/*
* 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 && !tls13_generate_handshake_secret(s, NULL, 0)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_FINAL_KEY_SHARE,
ERR_R_INTERNAL_ERROR);
return 0;
}
}
#endif /* !defined(OPENSSL_NO_TLS1_3) */
return 1;
}
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,
int external)
{
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];
unsigned char *early_secret;
#ifdef CHARSET_EBCDIC
static const unsigned char resumption_label[] = { 0x72, 0x65, 0x73, 0x20, 0x62, 0x69, 0x6E, 0x64, 0x65, 0x72, 0x00 };
static const unsigned char external_label[] = { 0x65, 0x78, 0x74, 0x20, 0x62, 0x69, 0x6E, 0x64, 0x65, 0x72, 0x00 };
#else
static const unsigned char resumption_label[] = "res binder";
static const unsigned char external_label[] = "ext binder";
#endif
const unsigned char *label;
size_t bindersize, labelsize, hashsize;
int hashsizei = EVP_MD_size(md);
int ret = -1;
int usepskfored = 0;
/* Ensure cast to size_t is safe */
if (!ossl_assert(hashsizei >= 0)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PSK_DO_BINDER,
ERR_R_INTERNAL_ERROR);
goto err;
}
hashsize = (size_t)hashsizei;
if (external
&& s->early_data_state == SSL_EARLY_DATA_CONNECTING
&& s->session->ext.max_early_data == 0
&& sess->ext.max_early_data > 0)
usepskfored = 1;
if (external) {
label = external_label;
labelsize = sizeof(external_label) - 1;
} else {
label = resumption_label;
labelsize = sizeof(resumption_label) - 1;
}
/*
* Generate the early_secret. On the server side we've selected a PSK to
* resume with (internal or external) so we always do this. On the client
* side we do this for a non-external (i.e. resumption) PSK or external PSK
* that will be used for early_data so that it is in place for sending early
* data. For client side external PSK not being used for early_data we
* generate it but store it away for later use.
*/
if (s->server || !external || usepskfored)
early_secret = (unsigned char *)s->early_secret;
else
early_secret = (unsigned char *)sess->early_secret;
if (!tls13_generate_secret(s, md, NULL, sess->master_key,
sess->master_key_length, early_secret)) {
/* SSLfatal() already called */
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) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PSK_DO_BINDER,
ERR_R_INTERNAL_ERROR);
goto err;
}
/* Generate the binder key */
if (!tls13_hkdf_expand(s, md, early_secret, label, labelsize, hash,
hashsize, binderkey, hashsize, 1)) {
/* SSLfatal() already called */
goto err;
}
/* Generate the finished key */
if (!tls13_derive_finishedkey(s, md, binderkey, finishedkey, hashsize)) {
/* SSLfatal() already called */
goto err;
}
if (EVP_DigestInit_ex(mctx, md, NULL) <= 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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 == SSL_HRR_PENDING) {
size_t hdatalen;
long hdatalen_l;
void *hdata;
hdatalen = hdatalen_l =
BIO_get_mem_data(s->s3.handshake_buffer, &hdata);
if (hdatalen_l <= 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PSK_DO_BINDER,
ERR_R_INTERNAL_ERROR);
goto err;
}
hdatalen -= PACKET_remaining(&hashprefix);
}
if (EVP_DigestUpdate(mctx, hdata, hdatalen) <= 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS_PSK_DO_BINDER,
ERR_R_INTERNAL_ERROR);
goto err;
}
mackey = EVP_PKEY_new_raw_private_key(EVP_PKEY_HMAC, NULL, finishedkey,
hashsize);
if (mackey == NULL) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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);
if (!ret)
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_TLS_PSK_DO_BINDER,
SSL_R_BINDER_DOES_NOT_VERIFY);
}
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)
{
if (!sent)
return 1;
if (!s->server) {
if (context == SSL_EXT_TLS1_3_ENCRYPTED_EXTENSIONS
&& sent
&& !s->ext.early_data_ok) {
/*
* If we get here then the server accepted our early_data but we
* later realised that it shouldn't have done (e.g. inconsistent
* ALPN)
*/
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_FINAL_EARLY_DATA,
SSL_R_BAD_EARLY_DATA);
return 0;
}
return 1;
}
if (s->max_early_data == 0
|| !s->hit
|| s->early_data_state != SSL_EARLY_DATA_ACCEPTING
|| !s->ext.early_data_ok
|| s->hello_retry_request != SSL_HRR_NONE
|| (s->allow_early_data_cb != NULL
&& !s->allow_early_data_cb(s,
s->allow_early_data_cb_data))) {
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)) {
/* SSLfatal() already called */
return 0;
}
}
return 1;
}
static int final_maxfragmentlen(SSL *s, unsigned int context, int sent)
{
/*
* Session resumption on server-side with MFL extension active
* BUT MFL extension packet was not resent (i.e. sent == 0)
*/
if (s->server && s->hit && USE_MAX_FRAGMENT_LENGTH_EXT(s->session)
&& !sent ) {
SSLfatal(s, SSL_AD_MISSING_EXTENSION, SSL_F_FINAL_MAXFRAGMENTLEN,
SSL_R_BAD_EXTENSION);
return 0;
}
/* Current SSL buffer is lower than requested MFL */
if (s->session && USE_MAX_FRAGMENT_LENGTH_EXT(s->session)
&& s->max_send_fragment < GET_MAX_FRAGMENT_LENGTH(s->session))
/* trigger a larger buffer reallocation */
if (!ssl3_setup_buffers(s)) {
/* SSLfatal() already called */
return 0;
}
return 1;
}
static int init_post_handshake_auth(SSL *s, unsigned int context)
{
s->post_handshake_auth = SSL_PHA_NONE;
return 1;
}
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