Commit 4771f23e authored by Matt Caswell's avatar Matt Caswell
Browse files

Don't fail on an out-of-order CCS in DTLS 



Fixes #4929

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6196)
parent 2ddfe60b

ssl/statem/statem.c

+1 −3
Original line number Diff line number Diff line
@@ -556,10 +556,8 @@ static SUB_STATE_RETURN read_state_machine(SSL *s) 
             * Validate that we are allowed to move to the new state and move

             * to that state if so

             */

            if (!transition(s, mt)) {

                ossl_statem_set_error(s);

            if (!transition(s, mt))

                return SUB_STATE_ERROR;

            }



            if (s->s3->tmp.message_size > max_message_size(s)) {

                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);

ssl/statem/statem_clnt.c

+15 −0
Original line number Diff line number Diff line
@@ -265,6 +265,21 @@ int ossl_statem_client_read_transition(SSL *s, int mt) 


 err:

    /* No valid transition found */

    if (SSL_IS_DTLS(s) && mt == SSL3_MT_CHANGE_CIPHER_SPEC) {

        BIO *rbio;



        /*

         * CCS messages don't have a message sequence number so this is probably

         * because of an out-of-order CCS. We'll just drop it.

         */

        s->init_num = 0;

        s->rwstate = SSL_READING;

        rbio = SSL_get_rbio(s);

        BIO_clear_retry_flags(rbio);

        BIO_set_retry_read(rbio);

        return 0;

    }

    ossl_statem_set_error(s);

    ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);

    SSLerr(SSL_F_OSSL_STATEM_CLIENT_READ_TRANSITION, SSL_R_UNEXPECTED_MESSAGE);

    return 0;

ssl/statem/statem_srvr.c

+15 −0
Original line number Diff line number Diff line
@@ -213,6 +213,21 @@ int ossl_statem_server_read_transition(SSL *s, int mt) 
    }



    /* No valid transition found */

    if (SSL_IS_DTLS(s) && mt == SSL3_MT_CHANGE_CIPHER_SPEC) {

        BIO *rbio;



        /*

         * CCS messages don't have a message sequence number so this is probably

         * because of an out-of-order CCS. We'll just drop it.

         */

        s->init_num = 0;

        s->rwstate = SSL_READING;

        rbio = SSL_get_rbio(s);

        BIO_clear_retry_flags(rbio);

        BIO_set_retry_read(rbio);

        return 0;

    }

    ossl_statem_set_error(s);

    ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);

    SSLerr(SSL_F_OSSL_STATEM_SERVER_READ_TRANSITION, SSL_R_UNEXPECTED_MESSAGE);

    return 0;