smbspool vs smbspool_krb5_wrapper

[Michael Tokarev <mjt@tls.msk.ru>]

Hi!

For a very long time, apparently, we ship smbspool
backend for cups in samba package in a wrong way.

source3/client/smbspool_krb5_wrapper.c reads:

/*
 * This is a helper binary to execute smbspool.
 *
 * It needs to be installed or symlinked as:
 *      /usr/lib/cups/backend/smb
 *
 * The permissions of the binary need to be set to 0700 so that it is executed
 * as root. The binary switches to the user which is passed via the environment
 * variable AUTH_UID, so we can access the kerberos ticket.
 */

And we have:
 /usr/lib/cups/backend/smb => /usr/bin/smbspool

Is it okay for smbspool to be run as root to start
with ? Or does cups run things as different user
when it has wider than 0700 file permissions?

Should it be

 usr/lib/cups/backend/smb =>
   usr/libexec/samba/smbspool_krb5_wrapper

instead?

(This is how the move to libexec "affects" cups: it doesn't).

But overall, does it really matter?  What this wrapper is
supposed to do, what _is_ this $AUTH_UID thing, when we
are run from cups? Is it a local user who submitted a
print job, and the backend runs under this local user?
How about remote print jobs?

Just guessing here. Can cups people answer some of that?

Thanks!

/mjt