RFR: 8245527: LDAP Cnannel Binding support for Java GSS/Kerberos
Alexey Bakhtin
alexey at azul.com
Mon May 25 15:33:33 UTC 2020
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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