Code review request, JDK-8052406, SSLv2Hello protocol may be filter out unexpectedly

[Xuelei Fan]

On 7/31/2014 9:11 AM, Wang Weijun wrote:
> 
> On Jul 31, 2014, at 8:54, Xuelei Fan <xuelei.fan at oracle.com> wrote:
> 
>> On 7/31/2014 8:14 AM, Wang Weijun wrote:
>>> The fix looks harmless, but I don't understand the test. What happens if SSLv2Hello is filtered out?
>>>
>> If SSLv2Hello is filtered out, this side would not support SSLv2Hello
>> any more.
> 
> The server side now only enables TLS_RSA_WITH_AES_128_CBC_SHA256. If other protocols are enabled, what will be the difference? You mean TLS 1.0 and 1.1 has built-in support for SSLv2Hello but TLS 1.2 does not?
> 
Protocols other then TLS v1.2 and SSLv2Hello would be filtered out,
i.e., cannot be negotiated as there is no suitable cipher suite for
those protocols ("TLS_RSA_WITH_AES_128_CBC_SHA256" only applies to TLS 1.2).

SSLv2Hello is a symbol to accept ClientHello message in SSLv2 format.
It is not a actual protocol, just a CLientHello message format.  The
actual negotiated protocol should be one of SSL 3.0/TLS 1.0/1.1/1.2.
Therefore, if there is one suitable protocol of SSL 3.0/TLS 1.0/1.1/1.2,
SSLv2Hello ClientHello message should be accepted.

If SSLv2Hello is not enabled, it means that ClientHello message in SSLv2
format should not be accepted during handshaking.  In this case, as will
result in that the server side would reject client request, as the
requested ClientHello message is in SSLv2 format.

Thanks,
Xuelei

> --Max
> 
>>  If SSLv2Hello format client hello requested, the server would
>> reject the connection.  In the test case, before the fix, the connection
>> cannot be established as server side filters out SSLv2Hello protocol.
>>
>> Thanks,
>> Xuelei
>>
>>> --Max
>>>
>>> On Jul 30, 2014, at 20:56, Xuelei Fan <xuelei.fan at oracle.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> Please review this fix for JDK-8052406:
>>>>
>>>> Webrev: http://cr.openjdk.java.net/~xuelei/8052406/webrev.00/
>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8049321
>>>>
>>>> For TLS connections, if no suitable cipher suite available for a
>>>> particular TLS protocol, such protocol should not be negotiated. For
>>>> example, if only "TLS_RSA_WITH_AES_128_CBC_SHA256" enabled, as it is
>>>> only supported by TLS version 1.2, the connection should be negotiated
>>>> TLS version 1 and 1.1.
>>>>
>>>> In SunJSSE implementation, we check the binding of enabled protocols and
>>>> enabled cipher suites.  SSLv2Hello may be improperly filter out when
>>>> making the checking above.  Actually, SSLv2Hello is not a real SSL/TLS
>>>> protocol, it is only used as the format of ClientHello message.  If
>>>> SSLv2Hello is enabled, it should not be filter out.
>>>>
>>>> This fix address the SunJSSE problem implementation above.
>>>>
>>>> Thanks,
>>>> Xuelei
>>>
>>
>