code review request: 7061379: [Kerberos] Cross-realm authentication fails, due to nameType problemThe

Weijun Wang weijun.wang at oracle.com
Thu Jul 14 00:24:51 PDT 2011


Ping again.

Thanks
Max

On 07/07/2011 09:10 AM, Weijun Wang wrote:
> Hi Valerie
>
> http://cr.openjdk.java.net/~weijun/7061379/webrev.00/
>
> The bug report says the TGS-REQ "asks for a KRB_NT_SRV_INST type whereas
> the kdc answers with a KRB_NT_PRINCIPAL type. Thus, equalsWithoutRealm
> function fails and authentication is refused". The KDC's behavior is a
> little abnormal but RFC 4120 6.2 [1] does point out:
>
> ... The name-type SHOULD be
> treated only as a hint to interpreting the meaning of a name. It is
> not significant when checking for equivalence.
>
> So I remove the name-type check in PrincipalName.equalsWithoutRealm().
> This also makes equals() transitive, which is good. The hashCode()
> method has never been dependent on the name-type, so there is no need to
> update it.
>
> The regression test introduced a new KDC option to set name-type for
> sname in a KDC-REP to be an arbitrary value, in order to prove it is now
> ignored in "checking for equivalence".
>
> Thanks
> Max
>
> [1] http://tools.ietf.org/html/rfc4120#section-6.2
>
> -------- Original Message --------
> *Change Request ID*: 7061379
> *Synopsis*: [Kerberos] Cross-realm authentication fails, due to nameType
> problem
>
>
> === *Description*
> ============================================================
> FULL PRODUCT VERSION :
> Java HotSpot(TM) 64-Bit Server VM (build 14.1-b02, mixed mode)
>
> /!\ same bug with open jdk 1.7
>
> ADDITIONAL OS VERSION INFORMATION :
> Linux x86_64 Intel(R) Xeon(R) CPU L5520 @ 2.27GHz GNU/Linux
>
> EXTRA RELEVANT SYSTEM CONFIGURATION :
> /!\ same bug with open jdk 1.7
>
> A DESCRIPTION OF THE PROBLEM :
> Authentication to remote server fails. Error doesn't appear in the logs
> but the debugger points out the following error:
>
> KRB_AP_ERR_MODIFIED (erreur 41) Message stream modified
> in sun.security.krb5.KrbKdcRep class, line 56
>
> Cross-realm authentication to one remote service is processed in
> sun.security.krb5.internal.CredentialsUtil class.
> It consists in the obtention of a token for the krbtgt/REALM1 at REALM2
> principal.
>
> Function acquireServiceCreds() negotiates with the kdc, by throwing
> requests and receiving responses. equalsWithoutRealm() function is called.
>
> The function equalsWithoutRealm() in sun.security.krb5.PrincipalName
> checks the conformity between principal asked in request and principal
> obtained in response.
> However, there is a type mismatch between the two krbtgt principals:
> request asks for a KRB_NT_SRV_INST type whereas the kdc answers with a
> KRB_NT_PRINCIPAL type. Thus, equalsWithoutRealm function fails and
> authentication is refused.
>
>
> STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
> Try to access from one realm to whatever remote 'kerberized' service.
> For example: GSSAPI and JNDI for remote LDAP server.
>
> EXPECTED VERSUS ACTUAL BEHAVIOR :
> EXPECTED -
> Expected result: successful authentication with remote service access.
> ACTUAL -
> Error is caught but not reported in system.out, and remote
> authentication fails.
>
> ERROR MESSAGES/STACK TRACES THAT OCCUR :
> KRB_AP_ERR_MODIFIED (erreur 41) Message stream modified
> in sun.security.krb5.KrbKdcRep class, line 56
>
> is reached but never thrown to the logs.
>
> REPRODUCIBILITY :
> This bug can be reproduced always.
>
> CUSTOMER SUBMITTED WORKAROUND :
> Modifying the acquireServiceCreds() function solves the problem. But
> maybe the best solution is to change the request for a cross-realm krbtgt.
>
> Line 134 in CredentialsUtil.java:
>
> for (cTgt = ccreds, i = 0; i < realms.length;)
> {
> // tempService = new ServiceName(PrincipalName.TGS_DEFAULT_SRV_NAME,
> // serviceRealm, realms[i]);
> if (!localRealm.equalsIgnoreCase(serviceRealm)) { //do cross-realm
> authentication
> if (DEBUG) {
> System.out.println(">>>DEBUG: Credentails request cross realm ticket for
> " + "krbtgt/" + serviceRealm + "@" + localRealm);
> }
> tempService = new ServiceName("krbtgt/" + serviceRealm + "@" + realms[i]);
> }else{
> tempService = new ServiceName(PrincipalName.TGS_DEFAULT_SRV_NAME,
> serviceRealm, realms[i]);
> }
>
> if (DEBUG)
> {
> System.out.println(">>> Credentials acquireServiceCreds: main loop: [" +
> i +"] tempService=" + tempService);
> }
> ...
> ...
> ...
>
> SUPPORT :
> YES
>



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