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From: Sam Vilain (sam_at_vilain.net)
Date: Mon 11 Aug 2003 - 16:47:31 BST

    Opinion Poll!

    let's assume each file and directory carry a tag which
    says "this is a file of context N", where N is the context
    number of a virtual server.

An idea I just had is to treat it like an extension to the user ID -
eg, if you are using 16 bit user IDs then the context + the uid is the
`system userid' of 32 bits, but with special behaviour (such as
setting a default, meaning `any context', etc) when the context part
is 0 or 1. That way, files are uniquely identifiable between

btw, where would you put those extra bits for each inode, is there
room in the ext2/reiser/etc reserved structures? Of course you could
use the top half of the nice shiny 32-bit UIDs in Linux 2.6 :-)

This would mean adding syntax to `chown' and/or `chgrp' to specify a
context name as well as a username (eg, chown root_at_vs1:other_at_vs1

It could also be a different command, chctx, as suggested elsewhere.
But personally, it looks like ownership to me.

     2) if a program of context N encounters a file of
        context M, where N != M ...

        a) on modify change the file to the new context?
        b) do not allow access to files from other contexts
           except context zero/one?
        c) allow modification while keeping the file
           in its 'original' context?

     3) consider a program creating a (hard)link to a file
        in another context (including zero/one), should ...

        a) the file change to the 'new' context?
        b) the file keep the old context?
        c) this operation be disallowed?

     4) consider a program removing a link to a file with
        more than one links, should the remaining links ...

        a) be still 'owned' by the removing context?
        b) be changed to context zero/one?

The behaviour should be exactly as if it were owned by a different

Sam Vilain, sam_at_vilain.net

C++, where only your friends can access your private parts.

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