linux-kernel - Re: [PATCH] afs: proc cells and rootcell are writeable

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Message-ID: <20140126202509.GA10275@gmail.com>
Date:	Sun, 26 Jan 2014 21:25:09 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	David Howells <dhowells@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-afs@...ts.infradead.org,
	Pali Rohár <pali.rohar@...il.com>
Subject: Re: [PATCH] afs: proc cells and rootcell are writeable


* Ingo Molnar <mingo@...nel.org> wrote:

> 
> * Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> 
> > On Sun, Jan 26, 2014 at 4:27 AM, David Howells <dhowells@...hat.com> wrote:
> > >
> > > -       p = proc_create("cells", 0, proc_afs, &afs_proc_cells_fops);
> > > +       p = proc_create("cells", S_IFREG | S_IRUGO | S_IWUSR, proc_afs, &afs_proc_cells_fops);
> > > -       p = proc_create("rootcell", 0, proc_afs, &afs_proc_rootcell_fops);
> > > +       p = proc_create("rootcell", S_IFREG | S_IRUGO | S_IWUSR, proc_afs, &afs_proc_rootcell_fops);
> > 
> > So the S_IFREG isn't necessary.
> > 
> > And quite frankly, I personally think S_IRUGO | S_IWUSR is _less_ 
> > readable than 0644. It's damn hard to parse those random letter 
> > combinations, and at least I have to really think about it, in a way 
> > that the octal representation does *not* make me go "I have to think 
> > about that".
> > 
> > So my personal preference would be to just see that simple 0644 in 
> > proc_create. Hmm?
> 
> Perhaps we could also generate the most common variants as:
> 
>  #define PERM__rw_r__r__		0644
>  #define PERM__r________		0400
>  #define PERM__r__r__r__		0444
>  #define PERM__r_xr_xr_x		0555
> 
> etc.
> 
> or something similar, more or less matching the output of 'ls -l'?

Another variant of this would be to do the following macro:

	PERM(R_X, R_X, R_X)
	PERM(R__, R__, R__)
	PERM(RW_, R__, R__)

With the advantage of separating the groups better and reducing the 
number of constants needed.

Thanks,

	Ingo
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