krb5 commit: Interop with Heimdal KDC for S4U2Self requests

https://github.com/krb5/krb5/commit/8e80ddbfdb479800c8e6ef7b287d400476578f8a
commit 8e80ddbfdb479800c8e6ef7b287d400476578f8a
Author: Isaac Boukris <[email protected]>
Date:   Wed Jun 10 01:32:56 2020 +0300

    Interop with Heimdal KDC for S4U2Self requests
    
    [MS-SFU] 3.1.5.1.1.1 says the KDC SHOULD send PA_S4U_X509_USER pa-data
    if the TGT session key is of a newer enctype.  Our S4U2Self client
    code has enforced this clause as if it were a MUST.  For consistency
    with Microsoft and interoperability with Heimdal (which does not
    implement PA_S4U_X509_USER), stop enforcing this constraint.
    
    [[email protected]: compressed code slightly; wrote commit message]
    
    ticket: 8919 (new)

 src/lib/krb5/krb/s4u_creds.c |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/src/lib/krb5/krb/s4u_creds.c b/src/lib/krb5/krb/s4u_creds.c
index 1f0ab85..5c2b6ff 100644
--- a/src/lib/krb5/krb/s4u_creds.c
+++ b/src/lib/krb5/krb/s4u_creds.c
@@ -302,16 +302,11 @@ verify_s4u2self_reply(krb5_context context,
                                           enc_padata,
                                           KRB5_PADATA_S4U_X509_USER);
 
-    /* XXX this will break newer enctypes with a MIT 1.7 KDC */
     rep_s4u_padata = krb5int_find_pa_data(context,
                                           rep_padata,
                                           KRB5_PADATA_S4U_X509_USER);
-    if (rep_s4u_padata == NULL) {
-        if (not_newer == FALSE || enc_s4u_padata != NULL)
-            return KRB5_KDCREP_MODIFIED;
-        else
-            return 0;
-    }
+    if (rep_s4u_padata == NULL)
+        return (enc_s4u_padata != NULL) ? KRB5_KDCREP_MODIFIED : 0;
 
     data.length = rep_s4u_padata->length;
     data.data = (char *)rep_s4u_padata->contents;