[openssl-dev] Extended master secret goober in s3_srvr.c

[Bill Cox]

Here's some code in master starting at line 594 in s3_srvr.c:

                if (!s->s3->handshake_buffer) {
                    SSLerr(SSL_F_SSL3_ACCEPT, ERR_R_INTERNAL_ERROR);
                    return -1;
                }
                /*
                 * For sigalgs freeze the handshake buffer. If we support
                 * extms we've done this already.
                 */
                if (!(s->s3->flags & SSL_SESS_FLAG_EXTMS)) {
                    s->s3->flags |= TLS1_FLAGS_KEEP_HANDSHAKE;
                    if (!ssl3_digest_cached_records(s))
                        return -1;
                }

The goober is that s->s3->flags does not have a flag for
SSL_SESS_FLAG_EXTMS.  This flag is defined for s->session->flags, not
s->s3->flags.  What happens is that s->s3->flags generally has bit 0 clear,
because this iis the flag for SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS.
Therefore, this generally runs, and we set TLS1_FLAGS_KEEP_HANDSHAKE even
if we have extended master secret support enabled.

I haven't figured out yet what this does in the code.  If it were really
bad, we would have heard about it already.  What was this code supposed to
do, and how should it get fixed?

Thanks,
Bill
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