RE: [PATCH v5] Documentation/checkpatch: Prefer strscpy/strscpy_pad over strcpy/strlcpy/strncpy

["Gote, Nitin R" <nitin.r.gote@intel.com>]

Hi,

> -----Original Message-----
> From: Gote, Nitin R [mailto:nitin.r.gote@intel.com]
> Sent: Tuesday, July 23, 2019 2:56 PM
> To: Joe Perches <joe@perches.com>; Kees Cook <keescook@chromium.org>
> Cc: corbet@lwn.net; akpm@linux-foundation.org; apw@canonical.com;
> linux-doc@vger.kernel.org; kernel-hardening@lists.openwall.com
> Subject: RE: [PATCH v5] Documentation/checkpatch: Prefer
> strscpy/strscpy_pad over strcpy/strlcpy/strncpy
> 
> 
> > -----Original Message-----
> > From: Joe Perches [mailto:joe@perches.com]
> > Sent: Monday, July 22, 2019 11:11 PM
> > To: Kees Cook <keescook@chromium.org>; Gote, Nitin R
> > <nitin.r.gote@intel.com>
> > Cc: corbet@lwn.net; akpm@linux-foundation.org; apw@canonical.com;
> > linux-doc@vger.kernel.org; kernel-hardening@lists.openwall.com
> > Subject: Re: [PATCH v5] Documentation/checkpatch: Prefer
> > strscpy/strscpy_pad over strcpy/strlcpy/strncpy
> >
> > On Mon, 2019-07-22 at 10:30 -0700, Kees Cook wrote:
> > > On Wed, Jul 17, 2019 at 10:00:05AM +0530, NitinGote wrote:
> > > > From: Nitin Gote <nitin.r.gote@intel.com>
> > > >
> > > > Added check in checkpatch.pl to
> > > > 1. Deprecate strcpy() in favor of strscpy().
> > > > 2. Deprecate strlcpy() in favor of strscpy().
> > > > 3. Deprecate strncpy() in favor of strscpy() or strscpy_pad().
> > > >
> > > > Updated strncpy() section in Documentation/process/deprecated.rst
> > > > to cover strscpy_pad() case.
> > > >
> > > > Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
> > >
> > > Reviewed-by: Kees Cook <keescook@chromium.org>
> > >
> > > Joe, does this address your checkpatch concerns?
> >
> > Well, kinda.
> >
> > strscpy_pad isn't used anywhere in the kernel.
> >
> > And
> >
> > +        "strncpy"				=> "strscpy, strscpy_pad or
> for non-
> > NUL-terminated strings, strncpy() can still be used, but destinations
> > should be marked with __nonstring",
> >
> > is a bit verbose.  This could be simply:
> >
> > +        "strncpy" => "strscpy - for non-NUL-terminated uses,
> > + strncpy() dst
> > should be __nonstring",
> >
>

Could you please give your opinion on below comment.
 
> But, if the destination buffer needs extra NUL-padding for remaining size of
> destination, then safe replacement is strscpy_pad().  Right?  If yes, then what
> is your opinion on below change :
> 
>         "strncpy" => "strscpy, strcpy_pad - for non-NUL-terminated uses,
> strncpy() dst should be __nonstring",
> 
> 

If you agree on this, then I will include this change in next patch version.
 
 > -Nitin