Patch for default Kerbers realm in AIX

[miguel.sanders at arcelormittal.com]

Hi 

I'm currently observing a rather bizarre situation when using password based Kerberos authentication in OpenSSH on AIX.
Even though AIX can authenticate a user via Kerberos (using the KRB5A load module), OpenSSH cannot Kerberos authenticate this user.
This is caused by the fact that the user has two attributes which OpenSSH doesn't take into account when forming the principal name of the user (attributes auth_name and auth_domain). 
If AIX user, myuser, has the attributes auth_name=someone and auth_domain=SOMEWHERE, then the Kerberos principal name would be someone at SOMEWHERE instead of myuser at DEFAULTREALM. By using the auth_domain attribute, requests are sent to to the SOMEWHERE realm instead of the default realm DEFAULTREALM, which is listed in the libdefaults section of the krb5.conf configuration file. 

If I look at the code I can see the following in auth-krb5.c on line 88, which causes this behaviour:

problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,&authctxt->krb5_user);

Since authctxt->pw->pw_name contains only the user name (without a realm), the default realm will be automatically appended according to the documentation of the krb5_parse_name call. Since this isn't the correct realm name (the overwritten auth_domain is the correct one), Kerberos authentication fails. If the auth_domain attribute is not set, the default realm name will be used.

Since this is rather new for me, I don't know what the procedure is to supply a patch for this. Any pointers?

Thank you very much!

Met vriendelijke groet
Best regards
Bien à vous

Miguel SANDERS
ArcelorMittal Gent

UNIX Systems & Storage
IT Supply Western Europe | John Kennedylaan 51
B-9042 Gent

T +32 9 347 3538 | F +32 9 347 4901 | M +32478 805 023
E miguel.sanders at arcelormittal.com
www.arcelormittal.com/gent


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