Re: [PATCH 06/10] security: fix documentation for the path_chmod hook

[Stephen Smalley]

On 2/7/19 9:09 AM, Edwin Zimmerman wrote:
> On Thursday, February 07, 2019 8:50 AM Al Viro wrote:
> > On Thu, Feb 07, 2019 at 03:44:54PM +0300, Denis Efremov wrote:
> > > The path_chmod hook was changed in the commit
> > > "switch security_path_chmod() to struct path *" (cdcf116d44e7).
> > > The argument @mnt was removed from the hook, @dentry was changed
> > > to @path. This patch updates the documentation accordingly.
> > >
> > > Signed-off-by: Denis Efremov <efremov@xxxxxxxxx>
> > > ---
> > >   include/linux/lsm_hooks.h | 3 +--
> > >   1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> > > index cb93972257be..5d6428d0027b 100644
> > > --- a/include/linux/lsm_hooks.h
> > > +++ b/include/linux/lsm_hooks.h
> > > @@ -304,8 +304,7 @@
> > >    *	Return 0 if permission is granted.
> > >    * @path_chmod:
> > >    *	Check for permission to change DAC's permission of a file or directory.
> > > - *	@dentry contains the dentry structure.
> > > - *	@mnt contains the vfsmnt structure.
> > > + *	@path contains the path structure.
> >
> > May I politely inquire about the value of these comments?  How much information
> > is provided by refering to an argument as "the dentry structure" or "the path
> > structure", especially when there's nothing immediately above that would introduce
> > either.  "Type of 'dentry' argument is somehow related to struct dentry,
> > try and guess what the value might be - we don't care, we just need every
> > argument commented"?
> >
> > Who needs that crap in the first place?
>
> The comments fill a valuable place to folks like me who are new to the linux security modules.
> In my spare time, I'm writing a new LSM specifically geared for parental controls uses, and the
> comments in lsm_hooks.h have helped me out more than once.  Perhaps the comments could
> be inproved by changing them to something like this:
> "@[arg] contains the [type] structure, defined in linux/[?].h"

I don't think so.  The point is not what type of structure but what 
object is being passed and why is it relevant to the hook, e.g.

+ @path contains the path structure for the file whose permissions are 
being modified

or similar.