r12422: Some kerberos comments and clarifications.

Andrew Bartlett
(This used to be commit 31046cd22b45de6c62c9f122a81cfc898e818308)

source4/auth/kerberos/kerberos-notes.txt

@@ -99,6 +99,13 @@ Jean-Baptiste.Marchand@hsc.fr reminds me:
 
 We implement this in hdb-ldb.
 
+Implicit names for Win2000 Accounts
+-----------------------------------
+
+Despite not having a DNS name, nor a servicePrincipalName on accounts
+created by computers running win2000, it appears we are expected to
+have an implicit mapping from host/computer.full.name and
+host/computer to it's entry.
 
 Returned Salt for PreAuthentication
 -----------------------------------
@@ -276,12 +283,8 @@ DCE-RPC service) and when interacting on a kerberos basis, the
 password is salted by the client.  (That is, no salt infromation
 appears to be convayed from the KDC to the member).
 
-In dealing with this modal, the traditional file keytab seems
+In dealing with this modal, we leverage both the traditional file
-outmoded, because it is not the primary source of the keys, and as
+keytab and in-MEMORY keytabs.  
-such we have replaced it with an IN-MEMORY keytab.  This avoids Samba4
-needing to deal with system files for it's internal operation.  (We
-will however forward-port parts of Samba3's net ads keytab, for the
-benifit of other applications).
 
 When dealing with a windows KDC, the behaviour regarding case
 sensitivity and canonacolisation must be accomidated.  This means that
@@ -296,9 +299,14 @@ cifs/foo@realm (winxp clients, using netbios)
 
 as well as all case variations on the above.  
 
-Because that all got 'too hard' to put into a real keytab (and because we
+Because that all got 'too hard' to put into a keytab in the
-still wanted to supply a keytab to the GSSAPI code), we use in-memory
+traditional way (with the client to specify the name), we either
-keytabs, and specify the target name.
+pre-compute the keys into a traditional keytab or make an in-MEMORY
+keytab at run time.  In both cases we specifiy the principal name to
+GSSAPI, which avoids the need to store duplicate principals.
+
+We use a 'private' keytab in our private dir, referenced from the
+secrets.ldb by default.
 
 Extra Heimdal functions used
 ----------------------------

source4/auth/kerberos/kerberos_util.c

@@ -89,6 +89,8 @@ krb5_error_code salt_principal_from_credentials(TALLOC_CTX *parent_ctx,
 	} 
 
 	if (ret == 0) {
+		/* This song-and-dance effectivly puts the principal
+		 * into talloc, so we can't loose it. */
 		mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 		mem_ctx->principal = *salt_princ;
 		talloc_set_destructor(mem_ctx, free_principal);
@@ -115,7 +117,8 @@ krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 	
 	princ_string = cli_credentials_get_principal(credentials, mem_ctx);
 
-	/* A NULL here has meaning, as the gssapi server case will then use the principal from the client */
+	/* A NULL here has meaning, as the gssapi server case will
+	 * then use the principal from the client */
 	if (!princ_string) {
 		talloc_free(mem_ctx);
 		princ = NULL;
@@ -548,7 +551,7 @@ static krb5_error_code remove_old_entries(TALLOC_CTX *parent_ctx,
 			 * because deletes during enumeration may not
 			 * always be consistant.
 			 *
-			 * Also, the enumeration locks the keytab
+			 * Also, the enumeration locks a FILE: keytab
 			 */
 		
 			krb5_kt_end_seq_get(smb_krb5_context->krb5_context, keytab, &cursor);