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Date: Sun, 6 Oct 2019 17:49:24 +0100
From: Salvatore Mesoraca <>
To: Jann Horn <>
Cc: kernel list <>, 
	Kernel Hardening <>, Linux-MM <>, 
	linux-security-module <>, 
	Alexander Viro <>, Brad Spengler <>, 
	Casey Schaufler <>, Christoph Hellwig <>, 
	Kees Cook <>, PaX Team <>, 
	"Serge E. Hallyn" <>, Thomas Gleixner <>, James Morris <>, 
	John Johansen <>
Subject: Re: [PATCH v5 04/12] S.A.R.A.: generic DFA for string matching

Salvatore Mesoraca <> wrote:
> Jann Horn <> wrote:
> >
> > On Sat, Jul 6, 2019 at 12:55 PM Salvatore Mesoraca
> > <> wrote:
> > > Creation of a generic Discrete Finite Automata implementation
> > > for string matching. The transition tables have to be produced
> > > in user-space.
> > > This allows us to possibly support advanced string matching
> > > patterns like regular expressions, but they need to be supported
> > > by user-space tools.
> >
> > AppArmor already has a DFA implementation that takes a DFA machine
> > from userspace and runs it against file paths; see e.g.
> > aa_dfa_match(). Did you look into whether you could move their DFA to
> > some place like lib/ and reuse it instead of adding yet another
> > generic rule interface to the kernel?
> Yes, using AppArmor DFA cloud be a possibility.
> Though, I didn't know how AppArmor's maintainers feel about this.
> I thought that was easier to just implement my own.
> Anyway I understand that re-using that code would be the optimal solution.
> I'm adding in CC AppArmor's maintainers, let's see what they think about this.

I don't want this to prevent SARA from being up-streamed.
Do you think that having another DFA here could be acceptable anyway?
Would it be better if I just drop the DFA an go back to simple string
matching to speed up things?

Thank you,


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