Re: what's next for the linux kernel?

From: Nikita Danilov
Date: Wed Oct 05 2005 - 07:17:46 EST


Luke Kenneth Casson Leighton writes:

[...]

> > That's exactly the point: Unix file system model is more flexible than
> > alternatives.
>
> *grin*. sorry - i have to disagree with you (but see below).
>
> i was called in to help a friend of mine at EDS to do a bastion sftp
> server to write some selinux policy files because POSIX filepermissions
> could not fulfil the requirements.

First, I was talking about flexibility attained through the separation
of notions of file and index. You just claimed elsewhere that this is
the direction ntfs took (with the introduction of hard-links).

Then, every security model has its weakness and corner cases. Try to
express

rw-r-xrw- (0656)

POSIX bits with canonical NT ACLs (hint: in NT allow-ACEs are
accumulated).

[...]

>
> POSIX permissions were designed to fit into what... 16 bits,
> so they didn't have a lot to play with.

That very good property for a security model: simplicity is a virtue
here.

Nikita.
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