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Description of problem: MIT Kerberos 1.14 seems to have changed the format of their keytab files, as hinted at in the release notes about key version numbers. Current versions of Java, seemingly all flavors, but first noticed in IBM's and also tested in OpenJDK, cannot read this keytab format. Attempts to use MIT-generated keytabs fail with strange errors, usually along the lines of null keys or inability to read the file. Version-Release number of selected component (if applicable): Tried current latest: java-1.8.0-ibm-1.8.0.3.20-1jpp.1.el7_2.x86_64 How reproducible: Always Steps to Reproduce: 1. Create a keytab using MIT Kerberos: $ ktutil ktutil: addent -password -p testuser -k 1 -e aes256-cts-hmac-sha1-96 Password for testuser@EXAMPLE.COM: ktutil: wkt test.keytab ktutil: q 2. Attempt to use the keytab in Java. $ /usr/lib/jvm/jre-ibm/bin/klist -k -t test.keytab Key table: test.keytab Number of entries: 0 $ /usr/lib/jvm/jre-ibm/bin/ktab -l -k test.keytab The format of key table test.keytab is incorrect. $ /usr/lib/jvm/jre-ibm/bin/kinit -k -t test.keytab testuser # Assumes testuser is in the database com.ibm.security.krb5.KrbException, status code: 25 message: Additional pre-authentication required Actual results: Odd error messages Expected results: Parsing and use of the keytab file Additional info: For verification, I also used Java's ktab program to generate a keytab. It created a usable keytab file for both Java and MIT Kerberos.
Has anyone else verified this bug? Is there a target date when it might be fixed?
The bug is filed against the IBM JDK, which I believe is provided to Red Hat as a series of binaries. You would thus need to contact IBM to fix the bug there. We could look at this as an OpenJDK bug if requested.
Additional testing reveals the following: OpenJDK 1.8.0.121-0.b13: Reads the keytab file Oracle 1.8.0.121-1jpp.1: Does not read the keytab file IBM 1.8.0.3.20-1jpp.1: Does not read the keytab file. Example program: import java.io.File; import javax.security.auth.kerberos.KerberosKey; import javax.security.auth.kerberos.KerberosPrincipal; import javax.security.auth.kerberos.KeyTab; public class keytab { public static void main( String[] argv ) { File keytabFile = new File( argv[0] ); KerberosPrincipal princ = new KerberosPrincipal( argv[1] ); KeyTab keytab = KeyTab.getInstance( keytabFile ); for( KerberosKey k : keytab.getKeys( princ ) ) { System.out.println( k.toString() ); } } } To run: java keytab <keytab_file> <principal in file> On keytabs created in older Kerberos distros, this will output the keys in the keytab. With keytabs created by current Kerberos in RHEL7, this will output nothing.
Correction: I had freshly installed the Oracle version and forgot the unrestricted policy. After installing the policy, Oracle's Java also read the keytab. So it appears that IBM Java is the only version that fails to read the keytab (even with their unrestricted policy in place).
Thanks. I was able to read a keytab file generated on RHEL 7's mit-krb5 with the app provided on both java-1.7.0-openjdk and java-1.8.0-openjdk. Looks like an IBM-specific issue.
After evaluating this issue, there are no plans to address it further or fix it in an upcoming release. Therefore, it is being closed. If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.