[rsbac] RC, ACL models questions

[Amon Ott]

On Mittwoch, 28. April 2004 12:03, sftf at yandex.ru wrote:
>   Could you answer on several questions?
>   1. How to do with ACL, so that it is impossible to delete DIR, but
>      FILEs and DIRs under it possible to delete ?

Remove DELETE from dir's mask and add a sufficient entry for group 0 to all 
files and dirs below.

Simple solution: Set FF flag no_rename_or_delete on this dir.

>   2. How to do with RC, so that it is impossible to delete DIR, but
>      FILEs and DIRs under it possible to delete, if this files/dirs MUST 
inherit parent FD type ?
>      (so parent DIR and all subDIRs and subFILEs all of one fd-type)

If they have the same type, there is no way to have different rights.

Same simple solution: Set FF flag no_rename_or_delete on this dir.

>   3. With RC model Default FD Create Type may set in ONE TYPE:
>      - Inherit_from_process
>      - Inherit_from_parent
>      - No_create_allowed
>      So can ONE USER with ONE ROLE within ONE process create two files
>      with different fd-types in the SAME directory ?
>
>      Of course without implicit setting type AFTER file creation.
>      So files in process of creation MUST have different types.

No, not yet. A special rc_create system call with a new RC special right 
SELECT is on my to-do list.

>      For example: useradd, userdel from shadow suit.
>      When you add or delete user useradd/userdel programm
>      CREATE NEW /etc/passwd, /etc/shadow, so this files inherit their 
fd-types from
>      parent dir or process. But I want that /etc had their own type 
(sys_etc),
>      /etc/passwd -  their own type (auth_userdb) and
>      /etc/shadow -  their own type(auth_shadowdb) ALWAYS.

I know this problem, and the whole passwd/shadow scheme sucks raw eggs. The 
way it works is a bad design mistake, if you want to make it a bit more 
secure. A stronger authentication system for RSBAC is on its way, but not 
yet done.

Until then, the OWL project has created something better, I am not sure 
about the tool name. Might be tcb.

Amon.
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