Commit baa45c3e authored by Matt Caswell's avatar Matt Caswell
Browse files

As a server don't select TLSv1.3 if we're not capable of it 



Check that we are either configured for PSK, or that we have a TLSv1.3
capable certificate type. DSA certs can't be used in TLSv1.3 and we
don't (currently) allow GOST ones either (owing to the lack of standard
sig algs).

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6650)
parent 4fd12788

ssl/statem/statem_lib.c

+35 −3
Original line number Diff line number Diff line
@@ -1485,6 +1485,35 @@ static int ssl_method_error(const SSL *s, const SSL_METHOD *method) 
    return 0;

}



/*

 * Only called by servers. Returns 1 if the server has a TLSv1.3 capable

 * certificate type, or has PSK configured. Otherwise returns 0.

 */

static int is_tls13_capable(const SSL *s)

{

    int i;



    if (s->psk_server_callback != NULL || s->psk_find_session_cb != NULL)

        return 1;



    for (i = 0; i < SSL_PKEY_NUM; i++) {

        /* Skip over certs disallowed for TLSv1.3 */

        switch (i) {

        case SSL_PKEY_DSA_SIGN:

        case SSL_PKEY_GOST01:

        case SSL_PKEY_GOST12_256:

        case SSL_PKEY_GOST12_512:

            continue;

        default:

            break;

        }

        if (ssl_has_cert(s, i))

            return 1;

    }



    return 0;

}



/*

 * ssl_version_supported - Check that the specified `version` is supported by

 * `SSL *` instance
@@ -1514,9 +1543,12 @@ int ssl_version_supported(const SSL *s, int version, const SSL_METHOD **meth) 
    for (vent = table;

         vent->version != 0 && version_cmp(s, version, vent->version) <= 0;

         ++vent) {

        if (vent->cmeth != NULL &&

            version_cmp(s, version, vent->version) == 0 &&

            ssl_method_error(s, vent->cmeth()) == 0) {

        if (vent->cmeth != NULL

                && version_cmp(s, version, vent->version) == 0

                && ssl_method_error(s, vent->cmeth()) == 0

                && (!s->server

                    || version != TLS1_3_VERSION

                    || is_tls13_capable(s))) {

            if (meth != NULL)

                *meth = vent->cmeth();

            return 1;