linux-kernel - Re: [PATCH 2/2] Version 9 (2.6.24-rc1) Smack: Simplified Mandatory Access Control Kernel

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Message-ID: <1865922a0710280546n40de6e4exe8b43ce2e444366d@mail.gmail.com>
Date:	Sun, 28 Oct 2007 14:46:36 +0200
From:	"Ahmed S. Darwish" <darwish.07@...il.com>
To:	"Al Viro" <viro@....linux.org.uk>
Cc:	casey@...aufler-ca.com, akpm@...l.org, torvalds@...l.org,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] Version 9 (2.6.24-rc1) Smack: Simplified Mandatory Access Control Kernel

On 10/28/07, Al Viro <viro@....linux.org.uk> wrote:
> On Sat, Oct 27, 2007 at 11:01:12AM +0200, Ahmed S. Darwish wrote:
> > The problem here (As discussed in private mails) is that the for loop
> > assumes that the beginning of given user-space buffer is the beginning
> > of a rule. This leads to situations where the rule becomes "ecret 20",
> > or "cret 20" instead of "Secret 20". Big input buffers/files leads
> > smack to recieve a rule like "Secret 20" in fragmented chunks like:
> >
> > write("<lots of rules before ours>\nSec", ..)
> > write("r", 1, ..)
> > write("et 20\n<remaing rules after ours>", ..)
> >
> > Parsing a rule in such tough conditions in _kernel space_ is very
> > hard. I began to feel that it will be much easier if we do the parsing
> > in a userspace utility and let smack accept only small buffers (80 char).
>
> For crying out louf, all it takes is a finite state machine...  BTW, folks,
> your parser *and* input language suck.  Really.  Silently allowing noise
> is Dumb(tm).
>

Ehem .., I really thought about the FSM thing but I thought it won't
be possible with concurrent writes (forgetting that several related
writes is done in one open(),release() session and we can lock writes
in open()).

<Getting back to coding>

-- 
Ahmed S. Darwish
Homepage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com
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