Code Review Request: JDK-6491070 (Support for RFC 5929-Channel Bindings)
David Lloyd
david.lloyd at redhat.com
Fri Sep 1 14:08:26 UTC 2017
I can say that from the perspective of SASL that we don't need any
special indication about handshake, and it would be much easier to
just read the material off of the engine, socket, or session as
appropriate.
On Thu, Aug 31, 2017 at 8:32 PM, Xuelei Fan <xuelei.fan at oracle.com> wrote:
> The failure-and-retry mechanism could a nightmare for some applications.
> Please think more how could we avoid it. If need more APIs, what the update
> may looks like and how complicated it could be?
>
> If required, Bernd's proposal can be extended a little bit to support
> operations other than listening.
>
> APIs maintain is very complicated, a good design may need more time
> currently, but could save much more in the future.
>
> Thanks,
> Xuelei
>
> On 8/31/2017 11:41 AM, Martin Balao wrote:
>>
>> Hi,
>>
>> The material is already cached in the handshaker if secure renegotiation
>> is enabled. However, I agree with you that we are going to cache the value
>> even when secure renegotiation is not enabled, thus, wasting roughly 12
>> bytes (as bytes for an empty array are already consumed). In fact, the exact
>> case -adding a few conditionals to webrev.02- is the one in which secure
>> renegotiation is disabled and extended master secret is enabled. GnuTls and
>> OpenSSL -including its derivatives like Boring SSL and Python (through
>> OpenSSL)- always cache this information.
>>
>> As for the empty / null cases, the API consumer was expected to ask for
>> the binding information after the TLS connection is established. It's on the
>> API consumer knowledge that asking for the information before (i.e.: just
>> after creating a disconnected socket) or while the handshake is taking
>> place, makes no sense and no valid value will be obtained (either we define
>> this as null or empty). For those providers that do not support this
>> feature, the information wouldn't have been available after the handshake.
>> However, I agree with you that before the handshake is completed there is no
>> means of knowing if the provider does support this API. My first webrev
>> (webrev.01) was throwing an UnsupportedOperationException to make this case
>> explicit but I had doubts regarding the real value it provides for the API
>> consumer. The proposed API was similar to Python, SSLBoring and GnuTLs.
>> However, handshake listener callbacks -as Bernd suggests- and the idea of
>> just exposing the handshake material (as a lower level API) sounds good to
>> me. I can give it a try. I propose then to bring the handshake information
>> as part of a HandshakeCompletedEvent instance, even though the callback
>> registrant may not consume it. Would that work for you?
>>
>> In regard to the handshake material update -which I assumed unlikely-, the
>> point in which a renegotiation may take place (from the server side) is when
>> reading data, not when writing. That cannot be controlled by the application
>> because it's JSSE internal and not exposed. Thus, an application may read
>> from the socket, get the handshake material and write a message using the
>> binding value -which we can make sure that is the valid one at that point-.
>> However, as soon as the application reads again from the socket, a
>> renegotiation -if requested by the client- may be processed and the binding
>> value gets updated. The higher level protocol may fail -because the binding
>> value was already sent but not processed on the other side- and a re-try
>> needed. This looks independent of whether we use the originally proposed API
>> or the handshake listener callback interface (or even a sync callback),
>> because the underlying problem is that the application cannot really control
>> the renegotiation flow in the lower layer (as RFC 5929 suggest). The options
>> I see are adding more complexity to the API and let the application control
>> the renegotiation flow or live with that and expect the application to
>> retry.
>>
>> Thanks,
>> Martin.-
>>
>> On Tue, Aug 29, 2017 at 4:34 PM, Xuelei Fan <xuelei.fan at oracle.com
>> <mailto:xuelei.fan at oracle.com>> wrote:
>>
>> On 8/26/2017 2:56 PM, Bernd Eckenfels wrote:
>> > How about only passing it to an extended handshake listener. The
>> > material does not have to be cached (the app can do it if needed)
>> and
>> > renegotiation works the same way. This can also be helpful for
>> things
>> > like logging the master secret (for wireshark decryption). It can
>> even
>> > handle auditing of session resumptions
>> Martin, what do you think about Bernd's proposal above and similar
>> callback mechanism?
>>
>> More comment inlines.
>>
>> On 8/29/2017 11:50 AM, Martin Balao wrote:
>>
>> Hi Xuelei,
>>
>> >There are a few protocols that can benefits from exporting
>> SSL/TLS handshake materials, including RFC 5929, RFC 5056, token
>> binding and TLS 1.3 itself. Can we define a general API so as
>> to exposing the handshake materials, so as to mitigate the
>> inflating of JSSE APIs? I may suggest make further evaluation
>> before move on to following design and code.
>>
>> Do you prefer an API like "public byte[]
>> getTlsHandshakeMaterial(String materialType)" (in SSLSocket and
>> SSLEngine) where "materialType" can eventually be
>> "clientFinishedMessage"/"finishedMessage" or
>> "serverFinishedMessage"/"peerFinishedMessage"?
>>
>> The problem of the APIs like that is, when applications call the
>> method, it is not always return the expected result, and the
>> implementation may have to cache the message even if an application
>> never use it. See more in the following example.
>>
>> I cannot think of "serverCertificate" or "masterKey" as this is
>> more related to a Session and not neccessarily to a handshake.
>> getTlsHandshakeMaterial would be a lower level API and would
>> move the burden of knowing which information is required for
>> "tls-unique" TLS channel binding to the API consumer. Looks more
>> like the OpenSSL approach (instead of the Python, SSLBoring or
>> GnuTls approaches). However, OpenSSL have specific methods for
>> each piece of information instead of a generic and parametrized
>> one. I.e.: SSL_get_finished or SSL_get_peer_finished. What other
>> information do you expect the Handshaker to provide?
>>
>> >The SunJSSE provider happens to cache the finished messages
>> in its implementation so you can use it for tls-unique, but it
>> may not be true for other provider or other channel bindings.
>> Need to define a more reliable approach to get the handshake
>> materials.
>>
>> I focused on SunJSSE provider. I'm not sure about how other
>> providers may implement this API and where they can get the
>> required information from, without knowing their internals. In
>> regard to SunJSSE and "tls-unique" binding type, I leveraged on
>> existing data. If data weren't already there, I would have to
>> figure out how to get it from the handshake -doing the same that
>> was already done would have been an option-. Do you prefer the
>> Handshaker to provide a function to get different information
>> and not just the finished hash? (as for the public
>> SSLSocket/SSLEngine "getTlsHandshakeMaterial" API). Which other
>> information may be useful to get from the Handshaker? What do
>> you mean by reliable? (given that this is all SunJSSE internal
>> and we have no external dependencies).
>>
>> Let consider the use of the API.
>> byte[] getTlsChannelBinding("tls_unique");
>>
>> I'm confusing when I try to use it by myself:
>> 1. provider does not implement this method
>> return null or empty?
>>
>> It happens because an old provider should still work in new JDK, but
>> old provider does not implement new APIs, or a new provider does not
>> support this feature.
>>
>> 2. the method is called before handshaking
>> return null or empty?
>>
>> 3. the method is called during handshaking
>> return null, empty or the channel binding value?
>>
>> 4. the method is called at the same time the handshaking completed?
>> return the channel binding value?
>>
>> 5. the method is called after the handshaking
>> return the channel binding value?
>>
>> 6. the method is called during renegoitation
>> return null, empty, the old binding value, or the new binding
>> value?
>>
>> 7. the method is called after handshaking
>> return old binding value, or the new binding value?
>>
>> 8. the method is called after the initial handshaking, but the
>> binding value is changed shortly after because of renegotiation.
>> how could application use the binding value?
>>
>> We need a clear define of the behavior of the method. It could be
>> complicated if the method is designed as
>> getTlsChannelBinding("tls_unique").
>>
>> I feel that handshake material should be captured when
>> 1. it is requested to capture the handshake material, and
>> 2. the handshake material get produced.
>>
>> For the getTlsChannelBinding("tls_unique") API, it is unknown:
>> 1. Is it required to capture the handshake material?
>> 2. Is the handshake material produced?
>>
>> The two points could result in a few unexpected problems, as the
>> above 8 items that we may want to consider.
>>
>> In regard to other channel bindings, it'll depend on the binding
>> type the way in which the information is obtained. I.e.:
>> "tls-unique" SunJSSE implementation leverages on cached finished
>> messages. However, "tls-server-end-point" leverages on stored
>> certificates that are obtained from the Session (not from the
>> handshaker). Is there any specific channel binding you are
>> concerned with?
>>
>> >If the channel binding is not required, it may be not
>> necessary to expose the handshake materials. Need to define a
>> solution to indicate the need of the exporting.
>>
>> Do you mean a lower layer knowing if the upper layer is going to
>> require that information and decide to provide it or not based
>> on that knowledge? I think I didn't get your point here.
>>
>> I mean, if an application want to support channel binding, the
>> provider can provider the channel binding service; If the an
>> application does not want channel binding, the provider should be
>> perform the channel binding service. The getTlsChannelBinding()
>> make the provider MUST perform channel binding cache or calculation
>> no matter application want it or not.
>>
>> >2. No way to know the update of the underlying handshake
>> materials.
>> >If renegotiation can takes place, need to define a interface
>> to indicate that so that application can response accordingly.
>> See section 3 and 7 of RFC 5929.
>>
>> I intentionally skipped this -at the cost of a spurious
>> authentication- to avoid adding complexity to the API. An
>> spurious authentication -which does not appear likely to me- can
>> easily be retried by the application. The RFC 5929 suggests APIs
>> through which the application can *control* the flow (i.e.: hold
>> a renegotitation). This would expose JSSE internals. This is
>> more than notifying. Notification, in my opinion, adds no value:
>> what if the application already used the binding token before
>> receiving the notification? The spurious authentication will
>> happen anyways and has to be handled -i.e. retried-. It's just a
>> timing issue. The real value is controlling the flow as the RFC
>> suggests, but at the cost of exposing JSSE internals.
>>
>> My understanding, the block of the protocol is to make sure
>> application is performing the channel binding with the right value,
>> or updating the value accordingly if necessary. If you skip this
>> and when renegotiation happen, the channel binding could be limited,
>> or may not work as expected.
>>
>> Thanks,
>> Xuelei
>>
>> Kind regards,
>> Martin.-
>>
>>
>> On Sat, Aug 26, 2017 at 5:25 PM, Xuelei Fan
>> <xuelei.fan at oracle.com <mailto:xuelei.fan at oracle.com>
>> <mailto:xuelei.fan at oracle.com <mailto:xuelei.fan at oracle.com>>>
>>
>> wrote:
>>
>> Hi Marin,
>>
>> Sorry for the delay.
>>
>> There are a few protocols that can benefits from exporting
>> SSL/TLS
>> handshake materials, including RFC 5929, RFC 5056, token
>> binding and
>> TLS 1.3 itself. Can we define a general API so as to
>> exposing the
>> handshake materials, so as to mitigate the inflating of
>> JSSE APIs? I may suggest make further evaluation before move
>> on to following
>> design and code.
>>
>> >
>>
>> http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/>>
>> I have two concerns about the design:
>>
>> 1. Channel binding may be not always required.
>> SSLSocket/SSLEngine.getTlsChannelBinding(String bindingType);
>>
>> The SunJSSE provider happens to cache the finished messages
>> in its
>> implementation so you can use it for tls-unique, but it may
>> not be
>> true for other provider or other channel bindings. Need to
>> define a
>> more reliable approach to get the handshake materials.
>>
>> If the channel binding is not required, it may be not
>> necessary to
>> expose the handshake materials. Need to define a solution to
>> indicate the need of the exporting.
>>
>> 2. No way to know the update of the underlying handshake
>> materials.
>> If renegotiation can takes place, need to define a interface
>> to
>> indicate that so that application can response
>> accordingly. See
>> section 3 and 7 of RFC 5929.
>>
>> Thanks,
>> Xuelei
>>
>> On 7/31/2017 8:53 AM, Martin Balao wrote:
>>
>> Hi,
>>
>> Here it is an update for the proposed TLS Channel
>> Bindings
>> support in OpenJDK:
>>
>> *
>>
>> http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/>>
>> (browse online)
>> *
>>
>> http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/6491070.webrev.02.zip
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/6491070.webrev.02.zip>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/6491070.webrev.02.zip
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.02/6491070.webrev.02.zip>>
>> (download)
>>
>> Changes since v01:
>>
>> * getTlsChannelBinding API changed to return null by
>> default
>> (if not implemented), instead of throwing an
>> UnsupportedOperationException.
>>
>> * "tls-server-end-point" TLS channel binding now
>> supported.
>>
>> Kind regards,
>> Martin.-
>>
>> On Wed, Jul 26, 2017 at 4:12 PM, Martin Balao
>> <mbalao at redhat.com <mailto:mbalao at redhat.com>
>> <mailto:mbalao at redhat.com <mailto:mbalao at redhat.com>>
>> <mailto:mbalao at redhat.com <mailto:mbalao at redhat.com>
>>
>> <mailto:mbalao at redhat.com <mailto:mbalao at redhat.com>>>>
>>
>> wrote:
>>
>> Hi,
>>
>> Here it is my proposal for JDK-6491070 (Support
>> for RFC
>> 5929-Channel
>> Bindings: e.g. public API to obtain TLS finished
>> message) [1]:
>>
>> *
>>
>> http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/>>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/>>>
>> *
>>
>> http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip>>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip>
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip
>>
>> <http://cr.openjdk.java.net/~sgehwolf/webrevs/mbalaoal/JDK-6491070/webrev.01/6491070.webrev.01.zip>>>
>>
>> Notes:
>> * Implementation based on Channel Bindings for
>> TLS (RFC
>> 5929) [2]
>>
>> * Only "tls-unique" currently supported
>>
>> Look forward to your comments.
>>
>> Kind regards,
>> Martin.-
>>
>> --
>> [1] -
>> https://bugs.openjdk.java.net/browse/JDK-6491070
>> <https://bugs.openjdk.java.net/browse/JDK-6491070>
>> <https://bugs.openjdk.java.net/browse/JDK-6491070
>> <https://bugs.openjdk.java.net/browse/JDK-6491070>>
>> <https://bugs.openjdk.java.net/browse/JDK-6491070
>> <https://bugs.openjdk.java.net/browse/JDK-6491070>
>> <https://bugs.openjdk.java.net/browse/JDK-6491070
>> <https://bugs.openjdk.java.net/browse/JDK-6491070>>>
>> [2] - https://tools.ietf.org/html/rfc5929
>> <https://tools.ietf.org/html/rfc5929>
>> <https://tools.ietf.org/html/rfc5929
>> <https://tools.ietf.org/html/rfc5929>>
>> <https://tools.ietf.org/html/rfc5929
>> <https://tools.ietf.org/html/rfc5929>
>> <https://tools.ietf.org/html/rfc5929
>> <https://tools.ietf.org/html/rfc5929>>>
>>
>>
>>
>>
>
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- DML
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