Commit 224135e9 authored by Matt Caswell's avatar Matt Caswell
Browse files

Continue the extensions refactor 



Add support for construction of extensions

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

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
parent 6b473aca

ssl/statem/extensions.c

+128 −15
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ typedef struct { 
    unsigned int type;

    int (*server_parse)(SSL *s, PACKET *pkt, int *al);

    int (*client_parse)(SSL *s, PACKET *pkt, int *al);

    int (*server_construct)(SSL *s, WPACKET *pkt, int *al);

    int (*client_construct)(SSL *s, WPACKET *pkt, int *al);

    unsigned int context;

} EXTENSION_DEFINITION;
@@ -48,6 +50,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_renegotiate,

        tls_parse_clienthello_renegotiate,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_SSL3_ALLOWED

        | EXT_TLS1_2_AND_BELOW_ONLY

    },
@@ -55,6 +59,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_server_name,

        tls_parse_clienthello_server_name,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO

        | EXT_TLS1_3_ENCRYPTED_EXTENSIONS

    },
@@ -63,6 +69,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_srp,

        tls_parse_clienthello_srp,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY

    },

#endif
@@ -71,12 +79,16 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_ec_point_formats,

        tls_parse_clienthello_ec_pt_formats,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_AND_BELOW_ONLY

    },

    {

        TLSEXT_TYPE_supported_groups,

        tls_parse_clienthello_supported_groups,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_3_ENCRYPTED_EXTENSIONS

    },

#endif
@@ -84,18 +96,24 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_session_ticket,

        tls_parse_clienthello_session_ticket,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY

    },

    {

        TLSEXT_TYPE_signature_algorithms,

        tls_parse_clienthello_sig_algs,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO

    },

    {

        TLSEXT_TYPE_status_request,

        tls_parse_clienthello_status_request,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_3_CERTIFICATE

    },

#ifndef OPENSSL_NO_NEXTPROTONEG
@@ -103,6 +121,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_next_proto_neg,

        tls_parse_clienthello_npn,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY

    },

#endif
@@ -110,6 +130,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_application_layer_protocol_negotiation,

        tls_parse_clienthello_alpn,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO

        | EXT_TLS1_3_ENCRYPTED_EXTENSIONS

    },
@@ -117,6 +139,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_use_srtp,

        tls_parse_clienthello_use_srtp,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO

        | EXT_TLS1_3_ENCRYPTED_EXTENSIONS | EXT_DTLS_ONLY

    },
@@ -124,6 +148,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        TLSEXT_TYPE_encrypt_then_mac,

        tls_parse_clienthello_etm,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_2_AND_BELOW_ONLY

    },

    {
@@ -135,6 +161,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
         */

        NULL,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO | EXT_TLS1_3_CERTIFICATE

    },

    {
@@ -148,6 +176,8 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        /* Processed inline as part of version selection */

        NULL,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS_IMPLEMENTATION_ONLY

    },

    {
@@ -155,12 +185,16 @@ static const EXTENSION_DEFINITION ext_defs[] = { 
        /* We send this, but don't read it */

        NULL,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO

    },

    {

        TLSEXT_TYPE_key_share,

        tls_parse_clienthello_key_share,

        NULL,

        NULL,

        NULL,

        EXT_CLIENT_HELLO | EXT_TLS1_3_SERVER_HELLO

        | EXT_TLS1_3_HELLO_RETRY_REQUEST | EXT_TLS_IMPLEMENTATION_ONLY

        | EXT_TLS1_3_ONLY
@@ -354,15 +388,33 @@ int tls_parse_all_extensions(SSL *s, RAW_EXTENSION *exts, size_t numexts, 
        currext->parsed = 1;



        parser = NULL;

        if (find_extension_definition(s, currext->type, &extdef))

        if (find_extension_definition(s, currext->type, &extdef)) {

            parser = s->server ? extdef->server_parse : extdef->client_parse;



            /* Check if extension is defined for our protocol. If not, skip */

            if ((SSL_IS_DTLS(s)

                        && (extdef->context & EXT_TLS_IMPLEMENTATION_ONLY) != 0)

                    || (s->version == SSL3_VERSION

                            && (extdef->context & EXT_SSL3_ALLOWED) == 0)

                    || (SSL_IS_TLS13(s)

                        && (extdef->context & EXT_TLS1_2_AND_BELOW_ONLY) != 0)

                    || (!SSL_IS_TLS13(s)

                        && (extdef->context & EXT_TLS1_3_ONLY) != 0))

                continue;

        }



        if (parser == NULL) {

            /*

             * Could be a custom extension. We only allow this if it is a non

             * resumed session on the server side

             * resumed session on the server side.

             * 

             * TODO(TLS1.3): We only allow old style <=TLS1.2 custom extensions.

             * We're going to need a new mechanism for TLS1.3 to specify which

             * messages to add the custom extensions to.

             */

            if ((!s->hit || !s->server)

                    && (context

                        & (EXT_CLIENT_HELLO | EXT_TLS1_2_SERVER_HELLO)) != 0

                    && custom_ext_parse(s, s->server, currext->type,

                                        PACKET_data(&currext->data),

                                        PACKET_remaining(&currext->data),
@@ -372,19 +424,6 @@ int tls_parse_all_extensions(SSL *s, RAW_EXTENSION *exts, size_t numexts, 
            continue;

        }



        /* Check if this extension is defined for our protocol. If not, skip */

        if ((SSL_IS_DTLS(s)

                    && (extdef->context & EXT_TLS_IMPLEMENTATION_ONLY) != 0)

                || (s->version == SSL3_VERSION

                        && (extdef->context & EXT_SSL3_ALLOWED) == 0)

                || (SSL_IS_TLS13(s)

                    && (extdef->context & EXT_TLS1_2_AND_BELOW_ONLY) != 0)

                || (!SSL_IS_TLS13(s)

                    && (extdef->context & EXT_TLS1_3_ONLY) != 0)

                || (s->server && extdef->server_parse == NULL)

                || (!s->server && extdef->client_parse == NULL))

            continue;



        if (!parser(s, &currext->data, al))

            return 0;

    }
@@ -409,6 +448,80 @@ int tls_parse_extension(SSL *s, int type, RAW_EXTENSION *exts, size_t numexts, 
    return tls_parse_all_extensions(s, ext, 1, al);

}



int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,

                             int *al)

{

    size_t loop;

    int addcustom = 0;



    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

                */

            || ((context & EXT_CLIENT_HELLO) != 0

               && !WPACKET_set_flags(pkt,

                                     WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH))) {

        *al = SSL_AD_INTERNAL_ERROR;

        SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);

        return 0;

    }



    for (loop = 0; loop < OSSL_NELEM(ext_defs); loop++) {

        /* Skip if not relevant for our context */

        if ((ext_defs[loop].context & context) == 0)

            continue;



        construct = s->server ? extdef->server_construct

                              : extdef->client_construct;



        /* Check if this extension is defined for our protocol. If not, skip */

        if ((SSL_IS_DTLS(s)

                    && (extdef->context & EXT_TLS_IMPLEMENTATION_ONLY) != 0)

                || (s->version == SSL3_VERSION

                        && (extdef->context & EXT_SSL3_ALLOWED) == 0)

                || (SSL_IS_TLS13(s)

                    && (extdef->context & EXT_TLS1_2_AND_BELOW_ONLY) != 0)

                || (!SSL_IS_TLS13(s)

                    && ((extdef->context & EXT_TLS1_3_ONLY) != 0

                        || (context & EXT_CLIENT_HELLO) != 0))

                || construct == NULL)

            continue;



        if (!construct(s, pkt, al))

            return 0;

    }





    /* Add custom extensions */

    if ((context & EXT_CLIENT_HELLO) != 0) {

        custom_ext_init(&s->cert->cli_ext);

        addcustom = 1;

    } else if (context & (EXT_TLS1_2_SERVER_HELLO) {

        /*

         * We already initialised the custom extensions during ClientHello

         * parsing.

         * 

         * TODO(TLS1.3): We're going to need a new custom extension mechanism

         * for TLS1.3, so that custom extensions can specify which of the

         * multiple message they wish to add themselves to.

         */

        addcustom = 1;

    }

    if (addcustom && !custom_ext_add(s, s->server, pkt, al)) {

        SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);

        return 0;

    }



    if (!WPACKET_close(pkt)) {

        *sl = SSL_AD_INTERNAL_ERROR;

        SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);

        return 0;

    }



    return 1;

}





/*

 * Parse the client's renegotiation binding and abort if it's not right