RFR: 8245527: LDAP Cnannel Binding support for Java GSS/Kerberos

[Alexey Bakhtin]

Hello Michael, Thomas,

Thank you a lot for review and suggestions.
I’ve fixed most of the issues except of fundamental one
I need more time to evaluate suggested usage of UnspecEmptyInetAddress subtype.

Updated webrev is available at: http://cr.openjdk.java.net/~abakhtin/8245527/webrev.v1/

Also, please see my comments below.

Regards
Alexey

> On 24 May 2020, at 02:38, Michael Osipov <1983-01-06 at gmx.net> wrote:
> 
> Am 2020-05-21 um 09:35 schrieb Alexey Bakhtin:
>> Hello,
>> 
>> Could you please review the following patch:
>> 
>> JBS: https://bugs.openjdk.java.net/browse/JDK-8245527
>> Webrev: http://cr.openjdk.java.net/~abakhtin/8245527/webrev.v0/
> 
> Let's go through your changes statically:
> 
> * The JIRA issue title has a typo
Thank you. Fixed in Jira
> * The word "cannot" is incorrectly spelled throughout all exception messages

Fixed from “can not” to “cannot"
> 
>> +            if (cbTypeProp.equals(TlsChannelBindingType.TLS_UNIQUE.getName())) {
>> +                throw new UnsupportedOperationException("LdapCtx: " +
>> +                        TlsChannelBindingType.TLS_UNIQUE.getName() + " type is not supported");
> 
> 
> "LdapCtx: " is redundant because the stacktrace will contain the class
> name already. A better message would be: "Channel binding type '%s' is
> not supported". Not just the plain value.

Exception message is corrected
> 
>> +            } else if (cbTypeProp.equals(TlsChannelBindingType.TLS_SERVER_END_POINT.getName())) {
>> +                if (connectTimeout == -1)
>> +                    throw new IllegalArgumentException(CHANNEL_BINDING_TYPE + " property requires " +
>> +                            CONNECT_TIMEOUT + " property is set.");
> 
> * Same here with the message
Not sure, What’s wrong with the message ?
> * The IAE is wrong because passed value is correct, but leads to an
> invalid state because connection timeout is -1. You need an
> IllegalStateException here.

Thank you. You are right again. Changed to IllegalStateException
> 
> Stupid question: how can one create a GSS security context when the TLS
> security context has not been established yet?

This logic already existed here. It could be a reason for it and I don’t want change it without strong purpose.
The only changes here is to prevent double setting of channel binding data.

> 
>> --- old/src/java.security.jgss/share/classes/sun/security/jgss/GSSContextImpl.java	2020-05-18 19:39:46.000000000 +0300
>> +++ new/src/java.security.jgss/share/classes/sun/security/jgss/GSSContextImpl.java	2020-05-18 19:39:46.000000000 +0300
>> @@ -531,9 +531,12 @@
>>     public void setChannelBinding(ChannelBinding channelBindings)
>>         throws GSSException {
>> 
>> -        if (mechCtxt == null)
>> +        if (mechCtxt == null) {
>> +            if (this.channelBindings  != null) {
>> +                throw new GSSException(GSSException.BAD_BINDINGS);
>> +            }
>>             this.channelBindings = channelBindings;
>> -
>> +        }
>>     }
> 
> I don't understand the purpose of this hunk. Is this safeguard to set
> bindings only once?
> 
>>     private static final int CHANNEL_BINDING_AF_INET = 2;
>>     private static final int CHANNEL_BINDING_AF_INET6 = 24;
>>     private static final int CHANNEL_BINDING_AF_NULL_ADDR = 255;
>> +    private static final int CHANNEL_BINDING_AF_UNSPEC = 0;
> 
> This should sort from 0 to 255 and not at the end.

OK. Moved to the top.

> 
>>     private int getAddrType(InetAddress addr) {
>> -        int addressType = CHANNEL_BINDING_AF_NULL_ADDR;
>> +        int addressType = CHANNEL_BINDING_AF_UNSPEC;
> 
>>   // initialize addrtype in CB first
>> -  cb->initiator_addrtype = GSS_C_AF_NULLADDR;
>> -  cb->acceptor_addrtype = GSS_C_AF_NULLADDR;
>> +  cb->initiator_addrtype = GSS_C_AF_UNSPEC;
>> +  cb->acceptor_addrtype = GSS_C_AF_UNSPEC;
> 
> This looks wrong to me -- as you already mentioned -- this violates RFC
> 2744, section 3.11, last sentence:
>> or omit addressing information, specifying
>>   GSS_C_AF_NULLADDR as the address-types.
> 
>>   /* release initiator address */
>> -  if (cb->initiator_addrtype != GSS_C_AF_NULLADDR) {
>> +  if (cb->initiator_addrtype != GSS_C_AF_NULLADDR &&
>> +      cb->initiator_addrtype != GSS_C_AF_UNSPEC) {
>>     resetGSSBuffer(&(cb->initiator_address));
>>   }
>>   /* release acceptor address */
>> -  if (cb->acceptor_addrtype != GSS_C_AF_NULLADDR) {
>> +  if (cb->acceptor_addrtype != GSS_C_AF_NULLADDR &&
>> +      cb->acceptor_addrtype != GSS_C_AF_UNSPEC) {
>>     resetGSSBuffer(&(cb->acceptor_address));
>>   }
> 
> Unspecified does not mean that it is null.
> 
>> +                                final byte[] prefix = (TlsChannelBindingType.TLS_SERVER_END_POINT.getName() + ":").getBytes();
>> +                                byte[] cbData =  Arrays.copyOf(prefix,
>> +                                        prefix.length + tlsCB.getData().length );
>> +                                System.arraycopy(tlsCB.getData(), 0, cbData,  prefix.length, tlsCB.getData().length);
> 
> Since you are calling "tlsCB.getData()" multiple times, this should go
> into a variable.

Temporary variable is added

> 
> 
>> +                                secCtx.setChannelBinding(new
> ChannelBinding(null, null, cbData));
> 
> Why not use new ChannelBinding(cbData)?

Right. updated

> 
>> +            String hashAlg = serverCertificate.getSigAlgName().
>> +                    replace("SHA", "SHA-").toUpperCase();
>> +            int ind = hashAlg.indexOf("WITH");
>> +            if (ind > 0) {
>> +                hashAlg = hashAlg.substring(0, ind);
>> +                if (hashAlg.equals("MD5") || hashAlg.equals("SHA-1")) {
>> +                    hashAlg = "SHA-256";
>> +                }
> 
> I have several problems with that, some might be hypothetical:
> 
> * toUpperCase() should be qualified with Locale.ROOT or Locate.ENGLISH

As you mentioned below AlgorithmId.getName() uses nameTable to return algorithm name.
Looking at implementation I do not think it is realistic to get name in the non-English locale.
I do not think it should be fixed

> * Looking at https://tools.ietf.org/html/rfc5280#section-4.1.1.2, then
> at sun.security.x509.AlgorithmId.getName() it uses nameTable to
> translate OIDs to readible names.
> 
> With indexOf("WITH") you are implying that the cert's sig alg may not
> use a cryptographic function, but this would mean that if the OID is
> 1.3.14.3.2.26 you'd turn "SHA-X" into "SHA--X" according to nameTable,
> wouldn't you?
> I also don't know how realistic "PBEWith..." is.
> 
> This likely needs more thought or I am missing something.
> 

I do not think it is realistic scenario to have certificate signature algorithm without crypto function.
indexOf(“WITH”) just used to find end out hash algorithm name.

> * Exception messages are inconsistent. Sometimes "TLS channel binding",
> sometimes just "channel binding". To avoid misunderstandings it should
> always read "TLS channel binding..".
> 

Messages are updated.

> Generally, I have two fundemental issues:
> * How do you know that address type must be UNSPEC and not NULLADDR?
> Trial and error?

I did not find any strict specification about TLS Channel Binding format in Windows server.
So, it was a lot of experiments, reading related forums and docs.
One of the doc, that turns me to try UNSPEC type is the following:
https://docs.microsoft.com/en-us/archive/blogs/openspecification/ntlm-and-channel-binding-hash-aka-extended-protection-for-authentication

> * Changing the default address type against the RFC will break every
> installation using channel bindings relying on it with cross GSS-API
> implementations.

I do not like this conflict between UNSPEC and NULLADDR types too, but I do not know How to better solve it.
The usage of UnspecEmptyInetAddress subtype is not quite clear to me yet. Who set this value and will it change org.ietf.jgss.ChannelBinding public api ? As I understand, Implementation cannot decide (without pplication request), What channel binding type is enabled on the server.

> 
> There must be another way to solve this. A system property would also be
> problematic because if you have a product which connects to MS and
> non-MS backends at the same time, channel bindings would be broken again.
> 
> What about introducing a UnspecEmptyInetAddress() which gives the proper
> AF type, but #getAddress() would return null? This should satisfy the
> requirements, InitialToken as well as the RFC. this of course needs to
> be properly passed to native providers too. GssKrb5Client would also
> need to know that this channel binding is explicitly for Active
> Directory and not some other, spec-compliant, SASL peer (property on
> LdapCtx?)
> 
> One could easily use this for custom code with a SSLServerSocket paired
> with Java SASL or in C, OpenSSL and Cyrus SASL.
> 
> Michael
> 
> PS: Yes, I am a nitpicker.

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