From: gezelter@rlgsc.com
Newsgroups: comp.os.vms
Subject: Re: Q: Homegrown COPY? FAQ?
Date: 6 Nov 92 14:43:53 GMT
Organization: Robert Gezelter Software Consultant, Flushing, NY

In article <68931@cup.portal.com>, Chris_F_Chiesa@cup.portal.com writes:
Chris,
 
An interesting problem! I have a couple of suggestions and observations 
on some of your questions. 
> ...
> 
>   Basically, I want to allow non-privileged users to copy files to which the
> existing baseline VMS protections/ACLs don't allow them access, subject to
> "permissions" "granted" by the owners of the files.  VMS protections/ACLs could
> probably do the job IF they could be made to take effect, and expire (and the
> corresponding ACL disappear from the file), at predetermined dates-and-times.) 
>  
Instead of re-writing COPY, how about using a daemon process 
(there is at least one in the DECUS library) to grant/revoke 
identifiers at the requested 'dates-and-times'. The daemon 
process need have no communications with the actual user 
processes. User processes will be able to use COPY, or any other 
program that they wish, to access the file. All of the sensitive 
security related code can be isolated to the daemon, which, in 
any event, will only be granting/revoking identifiers. 
 
While it would be rather CPU inefficient, you could even write 
the daemon in DCL and use AUTHORIZE to manage the grant/revoke 
operations. No privileged images need be written/installed. 
Additionally, the daemon will run from protected files in a 
protected account, so it will not be a hazard.
> 
>   * Implementing my project as a client which communicates with a detached
>     server process running a DCL command procedure which verifies the client
>     commands and then issues actual VMS COPY commands.  Has the advantage
>     that it uses "real VMS COPY," and can therefore support the full normal
>     behavior of same.  Has the disadvantage that now I have to deal with 
>     security-of-interprocess-communication issues.  What's the most secure
>     way to have these things talk to each other?  Mailboxes?  Shared global
>     sections?  Lock manager?
> 
All of the mechanisms for implementing interprocess 
communications are, for most intents and purposes, at the same 
security level. If you have sufficient privileges to snoop on a 
global section, you can probably snoop (or at least disrupt) a 
mailbox. My personal preference for interprocess communications 
is through DECnet, which makes the case of LAVc and other 
clustered systems easier.
 
> ... deleted ...
>
>   Thanks in advance,
> 
>     Chris Chiesa
>     Chris_F_Chiesa@cup.portal.com
-- 
 
I hope that the above is of assistance. If you have any 
questions, or if I can be of assistance, please feel free to 
contact me via Email or phone.
 
- Bob
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