[PATCH] afs: proc cells and rootcell are writeable
Ingo Molnar
mingo at kernel.org
Sun Jan 26 15:19:28 EST 2014
* Linus Torvalds <torvalds at linux-foundation.org> wrote:
> On Sun, Jan 26, 2014 at 4:27 AM, David Howells <dhowells at redhat.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'?
That would also make security bugs in this area apparent at first
sight. The number of people who can recognize during review that
PERM_rw__w__w is probably unwise is probably two orders of magnitude
than those who can interpret octal 0622 at a glance.
Thanks,
Ingo
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