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Move ServerHello extension parsing into the new extension framework

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Perl changes reviewed by Richard Levitte. Non-perl changes reviewed by Rich
Salz

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
This commit is contained in:
Matt Caswell 2016-11-28 16:15:51 +00:00
parent 70af3d8ed7
commit 332eb39088
7 changed files with 163 additions and 196 deletions
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3
include/openssl/ssl.h
View File

@ -2308,6 +2308,9 @@ int ERR_load_SSL_strings(void);
# define SSL_F_TLS_CONSTRUCT_SERVER_SESSION_TICKET 460
# define SSL_F_TLS_CONSTRUCT_SERVER_STATUS_REQUEST 461
# define SSL_F_TLS_CONSTRUCT_SERVER_USE_SRTP 462
# define SSL_F_TLS_EXT_FINAL_ 484
# define SSL_F_TLS_EXT_FINAL_EC_PT_FORMATS 485
# define SSL_F_TLS_EXT_FINAL_EMS 486
# define SSL_F_TLS_EXT_FINAL_RENEGOTIATE 483
# define SSL_F_TLS_GET_MESSAGE_BODY 351
# define SSL_F_TLS_GET_MESSAGE_HEADER 387

4
ssl/ssl_err.c
View File

@ -338,6 +338,10 @@ static ERR_STRING_DATA SSL_str_functs[] = {
"tls_construct_server_status_request"},
{ERR_FUNC(SSL_F_TLS_CONSTRUCT_SERVER_USE_SRTP),
"tls_construct_server_use_srtp"},
{ERR_FUNC(SSL_F_TLS_EXT_FINAL_), "tls_ext_final_ems"},
{ERR_FUNC(SSL_F_TLS_EXT_FINAL_EC_PT_FORMATS),
"tls_ext_final_ec_pt_formats"},
{ERR_FUNC(SSL_F_TLS_EXT_FINAL_EMS), "tls_ext_final_ems"},
{ERR_FUNC(SSL_F_TLS_EXT_FINAL_RENEGOTIATE), "tls_ext_final_renegotiate"},
{ERR_FUNC(SSL_F_TLS_GET_MESSAGE_BODY), "tls_get_message_body"},
{ERR_FUNC(SSL_F_TLS_GET_MESSAGE_HEADER), "tls_get_message_header"},

1
ssl/ssl_locl.h
View File

@ -2103,7 +2103,6 @@ __owur int tls1_get_curvelist(SSL *s, int sess, const unsigned char **pcurves,
void ssl_set_default_md(SSL *s);
__owur int tls1_set_server_sigalgs(SSL *s);
__owur int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt);
__owur RAW_EXTENSION *tls_get_extension_by_type(RAW_EXTENSION *exts,
size_t numexts,
unsigned int type);

145
ssl/statem/extensions.c
View File

@ -15,7 +15,14 @@ static int tls_ext_final_renegotiate(SSL *s, unsigned int context, int sent,
static int tls_ext_init_server_name(SSL *s, unsigned int context);
static int tls_ext_final_server_name(SSL *s, unsigned int context, int sent,
int *al);
#ifndef OPENSSL_NO_EC
static int tls_ext_final_ec_pt_formats(SSL *s, unsigned int context, int sent,
int *al);
#endif
static int tls_ext_init_session_ticket(SSL *s, unsigned int context);
static int tls_ext_init_status_request(SSL *s, unsigned int context);
static int tls_ext_final_status_request(SSL *s, unsigned int context, int sent,
int *al);
#ifndef OPENSSL_NO_NEXTPROTONEG
static int tls_ext_init_npn(SSL *s, unsigned int context);
#endif
@ -26,6 +33,8 @@ static int tls_ext_init_sig_algs(SSL *s, unsigned int context);
static int tls_ext_init_srp(SSL *s, unsigned int context);
#endif
static int tls_ext_init_etm(SSL *s, unsigned int context);
static int tls_ext_init_ems(SSL *s, unsigned int context);
static int tls_ext_final_ems(SSL *s, unsigned int context, int sent, int *al);
#ifndef OPENSSL_NO_SRTP
static int tls_ext_init_srtp(SSL *s, unsigned int context);
#endif
@ -122,7 +131,7 @@ static const EXTENSION_DEFINITION ext_defs[] = {
tls_parse_server_ec_pt_formats,
tls_construct_server_ec_pt_formats,
tls_construct_client_ec_pt_formats,
NULL,
tls_ext_final_ec_pt_formats,
EXT_CLIENT_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
},
{
@ -138,7 +147,7 @@ static const EXTENSION_DEFINITION ext_defs[] = {
#endif
{
TLSEXT_TYPE_session_ticket,
NULL,
tls_ext_init_session_ticket,
tls_parse_client_session_ticket,
tls_parse_server_session_ticket,
tls_construct_server_session_ticket,
@ -164,7 +173,7 @@ static const EXTENSION_DEFINITION ext_defs[] = {
tls_parse_server_status_request,
tls_construct_server_status_request,
tls_construct_client_status_request,
NULL,
tls_ext_final_status_request,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_CERTIFICATE
},
@ -239,12 +248,12 @@ static const EXTENSION_DEFINITION ext_defs[] = {
#endif
{
TLSEXT_TYPE_extended_master_secret,
NULL,
tls_ext_init_ems,
tls_parse_client_ems,
tls_parse_server_ems,
tls_construct_server_ems,
tls_construct_client_ems,
NULL,
tls_ext_final_ems,
EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY
},
{
@ -697,8 +706,22 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
static int tls_ext_final_renegotiate(SSL *s, unsigned int context, int sent,
int *al)
{
if (!s->server)
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_TLS_EXT_FINAL_RENEGOTIATE,
SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
return 0;
}
return 1;
}
/* Need RI if renegotiating */
if (s->renegotiate
@ -710,6 +733,7 @@ static int tls_ext_final_renegotiate(SSL *s, unsigned int context, int sent,
return 0;
}
return 1;
}
@ -727,9 +751,6 @@ static int tls_ext_final_server_name(SSL *s, unsigned int context, int sent,
int ret = SSL_TLSEXT_ERR_NOACK;
int altmp = SSL_AD_UNRECOGNIZED_NAME;
if (!s->server)
return 1;
if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
ret = s->ctx->tlsext_servername_callback(s, &altmp,
s->ctx->tlsext_servername_arg);
@ -756,6 +777,58 @@ static int tls_ext_final_server_name(SSL *s, unsigned int context, int sent,
}
}
#ifndef OPENSSL_NO_EC
static int tls_ext_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->tlsext_ecpointformatlist != NULL)
&& (s->tlsext_ecpointformatlist_length > 0)
&& (s->session->tlsext_ecpointformatlist != NULL)
&& (s->session->tlsext_ecpointformatlist_length > 0)
&& ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))) {
/* we are using an ECC cipher */
size_t i;
unsigned char *list;
int found_uncompressed = 0;
list = s->session->tlsext_ecpointformatlist;
for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++) {
if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
found_uncompressed = 1;
break;
}
}
if (!found_uncompressed) {
SSLerr(SSL_F_TLS_EXT_FINAL_EC_PT_FORMATS,
SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
return 0;
}
}
return 1;
}
#endif
static int tls_ext_init_session_ticket(SSL *s, unsigned int context)
{
if (!s->server)
s->tlsext_ticket_expected = 0;
return 1;
}
static int tls_ext_init_status_request(SSL *s, unsigned int context)
{
if (s->server)
@ -764,11 +837,27 @@ static int tls_ext_init_status_request(SSL *s, unsigned int context)
return 1;
}
static int tls_ext_final_status_request(SSL *s, unsigned int context, int sent,
int *al)
{
if (s->server)
return 1;
/*
* Ensure we get sensible values passed to tlsext_status_cb in the event
* that we don't receive a status message
*/
OPENSSL_free(s->tlsext_ocsp_resp);
s->tlsext_ocsp_resp = NULL;
s->tlsext_ocsp_resplen = 0;
return 1;
}
#ifndef OPENSSL_NO_NEXTPROTONEG
static int tls_ext_init_npn(SSL *s, unsigned int context)
{
if (s->server)
s->s3->next_proto_neg_seen = 0;
s->s3->next_proto_neg_seen = 0;
return 1;
}
@ -776,15 +865,14 @@ static int tls_ext_init_npn(SSL *s, unsigned int context)
static int tls_ext_init_alpn(SSL *s, unsigned int context)
{
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = NULL;
if (s->server) {
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = NULL;
s->s3->alpn_selected_len = 0;
OPENSSL_free(s->s3->alpn_proposed);
s->s3->alpn_proposed = NULL;
s->s3->alpn_proposed_len = 0;
}
return 1;
}
@ -844,8 +932,33 @@ static int tls_ext_init_srp(SSL *s, unsigned int context)
static int tls_ext_init_etm(SSL *s, unsigned int context)
{
if (s->server)
s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
return 1;
}
static int tls_ext_init_ems(SSL *s, unsigned int context)
{
if (!s->server)
s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
return 1;
}
static int tls_ext_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_TLS_EXT_FINAL_EMS, SSL_R_INCONSISTENT_EXTMS);
return 0;
}
}
return 1;
}

168
ssl/statem/extensions_clnt.c
View File

@ -1033,171 +1033,3 @@ int tls_parse_server_key_share(SSL *s, PACKET *pkt, int *al)
return 1;
}
static int ssl_scan_serverhello_tlsext(SSL *s, PACKET *pkt, int *al)
{
RAW_EXTENSION *extensions = NULL;
PACKET extpkt;
#ifndef OPENSSL_NO_NEXTPROTONEG
s->s3->next_proto_neg_seen = 0;
#endif
s->tlsext_ticket_expected = 0;
OPENSSL_free(s->s3->alpn_selected);
s->s3->alpn_selected = NULL;
s->s3->flags &= ~TLS1_FLAGS_ENCRYPT_THEN_MAC;
s->s3->flags &= ~TLS1_FLAGS_RECEIVED_EXTMS;
if (!PACKET_as_length_prefixed_2(pkt, &extpkt)) {
/* Extensions block may be completely absent in SSLv3 */
if (s->version != SSL3_VERSION || PACKET_remaining(pkt) != 0) {
*al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_BAD_LENGTH);
return 0;
}
PACKET_null_init(&extpkt);
}
/*
* TODO(TLS1.3): We give multiple contexts for now until we're ready to
* give something more specific
*/
if (!tls_collect_extensions(s, &extpkt, EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| EXT_TLS1_3_CERTIFICATE,
&extensions, al))
return 0;
/*
* Determine if we need to see RI. Strictly speaking if we want to avoid
* an attack we should *always* see RI even on initial server hello
* because the client doesn't see any renegotiation during an attack.
* However this would mean we could not connect to any server which
* doesn't support RI so for the immediate future tolerate RI absence
*/
if (!(s->options & SSL_OP_LEGACY_SERVER_CONNECT)
&& !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)
&& !extensions[TLSEXT_IDX_renegotiate].present) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT,
SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
return 0;
}
if (!tls_parse_all_extensions(s, EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| EXT_TLS1_3_CERTIFICATE,
extensions,al))
return 0;
if (s->hit) {
/*
* Check extended master secret extension is consistent with
* original session.
*/
if (!(s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) !=
!(s->session->flags & SSL_SESS_FLAG_EXTMS)) {
*al = SSL_AD_HANDSHAKE_FAILURE;
SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT, SSL_R_INCONSISTENT_EXTMS);
return 0;
}
}
return 1;
}
static int ssl_check_serverhello_tlsext(SSL *s)
{
int ret = SSL_TLSEXT_ERR_NOACK;
int al = SSL_AD_UNRECOGNIZED_NAME;
#ifndef OPENSSL_NO_EC
/*
* If we are client and using an elliptic curve cryptography cipher
* suite, then if server returns an EC point formats lists extension it
* must contain uncompressed.
*/
unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
if ((s->tlsext_ecpointformatlist != NULL)
&& (s->tlsext_ecpointformatlist_length > 0)
&& (s->session->tlsext_ecpointformatlist != NULL)
&& (s->session->tlsext_ecpointformatlist_length > 0)
&& ((alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA))) {
/* we are using an ECC cipher */
size_t i;
unsigned char *list;
int found_uncompressed = 0;
list = s->session->tlsext_ecpointformatlist;
for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++) {
if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
found_uncompressed = 1;
break;
}
}
if (!found_uncompressed) {
SSLerr(SSL_F_SSL_CHECK_SERVERHELLO_TLSEXT,
SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
return -1;
}
}
ret = SSL_TLSEXT_ERR_OK;
#endif /* OPENSSL_NO_EC */
if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
ret =
s->ctx->tlsext_servername_callback(s, &al,
s->ctx->tlsext_servername_arg);
else if (s->initial_ctx != NULL
&& s->initial_ctx->tlsext_servername_callback != 0)
ret =
s->initial_ctx->tlsext_servername_callback(s, &al,
s->
initial_ctx->tlsext_servername_arg);
/*
* Ensure we get sensible values passed to tlsext_status_cb in the event
* that we don't receive a status message
*/
OPENSSL_free(s->tlsext_ocsp_resp);
s->tlsext_ocsp_resp = NULL;
s->tlsext_ocsp_resplen = 0;
switch (ret) {
case SSL_TLSEXT_ERR_ALERT_FATAL:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
return -1;
case SSL_TLSEXT_ERR_ALERT_WARNING:
ssl3_send_alert(s, SSL3_AL_WARNING, al);
return 1;
case SSL_TLSEXT_ERR_NOACK:
s->servername_done = 0;
default:
return 1;
}
}
int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt)
{
int al = -1;
if (s->version < SSL3_VERSION)
return 1;
if (ssl_scan_serverhello_tlsext(s, pkt, &al) <= 0) {
ssl3_send_alert(s, SSL3_AL_FATAL, al);
return 0;
}
if (ssl_check_serverhello_tlsext(s) <= 0) {
SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT, SSL_R_SERVERHELLO_TLSEXT);
return 0;
}
return 1;
}

37
ssl/statem/statem_clnt.c
View File

@ -1058,13 +1058,14 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL *s, PACKET *pkt)
{
STACK_OF(SSL_CIPHER) *sk;
const SSL_CIPHER *c;
PACKET session_id;
PACKET session_id, extpkt;
size_t session_id_len;
const unsigned char *cipherchars;
int i, al = SSL_AD_INTERNAL_ERROR;
unsigned int compression;
unsigned int sversion;
int protverr;
RAW_EXTENSION *extensions = NULL;
#ifndef OPENSSL_NO_COMP
SSL_COMP *comp;
#endif
@ -1297,17 +1298,34 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL *s, PACKET *pkt)
#endif
/* TLS extensions */
if (!ssl_parse_serverhello_tlsext(s, pkt)) {
SSLerr(SSL_F_TLS_PROCESS_SERVER_HELLO, SSL_R_PARSE_TLSEXT);
goto err;
}
if (PACKET_remaining(pkt) != 0) {
/* wrong packet length */
if (PACKET_remaining(pkt) == 0) {
PACKET_null_init(&extpkt);
} else if (!PACKET_as_length_prefixed_2(pkt, &extpkt)) {
al = SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_TLS_PROCESS_SERVER_HELLO, SSL_R_BAD_PACKET_LENGTH);
SSLerr(SSL_F_TLS_PROCESS_SERVER_HELLO, SSL_R_BAD_LENGTH);
goto f_err;
}
/*
* TODO(TLS1.3): We give multiple contexts for now until we're ready to
* give something more specific
*/
if (!tls_collect_extensions(s, &extpkt, EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| EXT_TLS1_3_CERTIFICATE,
&extensions, &al))
goto f_err;
if (!tls_parse_all_extensions(s, EXT_TLS1_2_SERVER_HELLO
| EXT_TLS1_3_SERVER_HELLO
| EXT_TLS1_3_ENCRYPTED_EXTENSIONS
| EXT_TLS1_3_CERTIFICATE,
extensions, &al))
goto f_err;
#ifndef OPENSSL_NO_SCTP
if (SSL_IS_DTLS(s) && s->hit) {
unsigned char sctpauthkey[64];
@ -1350,7 +1368,6 @@ MSG_PROCESS_RETURN tls_process_server_hello(SSL *s, PACKET *pkt)
return MSG_PROCESS_CONTINUE_READING;
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
err:
ossl_statem_set_error(s);
return MSG_PROCESS_ERROR;
}

1
ssl/statem/statem_locl.h
View File

@ -266,4 +266,3 @@ int tls_parse_server_use_srtp(SSL *s, PACKET *pkt, int *al);
int tls_parse_server_etm(SSL *s, PACKET *pkt, int *al);
int tls_parse_server_ems(SSL *s, PACKET *pkt, int *al);
int tls_parse_server_key_share(SSL *s, PACKET *pkt, int *al);
int ssl_parse_serverhello_tlsext(SSL *s, PACKET *pkt);