RFR: 8245527: LDAP Cnannel Binding support for Java GSS/Kerberos
Alexey Bakhtin
alexey at azul.com
Wed May 27 09:42:20 UTC 2020
Hello Valerie,
Unfortunately, Windows LDAP server with LdapEnforceChannelBinding=2 does not accept GSS_C_AF_NULLADDR address type.
This is exact reason of these changes.
I’ve tried to fix inconsistency of address type value in the latest webrev:
http://cr.openjdk.java.net/~abakhtin/8245527/webrev.v2/
This fix allows to set GSS_C_AF_UNSPEC address type for the tls-server-end-point channel binding only
Regards
Alexey
> On 26 May 2020, at 23:37, Valerie Peng <valerie.peng at oracle.com> wrote:
>
> I am also concerned about the changes in GSSLibStub.c about the default value being GSS_C_AF_UNSPEC instead of GSS_C_AF_NULLADDR (line 194-195).
>
> Can you try and see if Window works with GSS_C_AF_NULLADDR? If yes, I'd prefer to not changing the default value for addresstype for the same reason which Michael has already stated.
>
> Thanks,
> Valerie
>
>
> On 5/25/2020 8:33 AM, Alexey Bakhtin wrote:
>> 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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