linux-kernel - Re: [PATCH] tpm: move struct tpm_class

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160903062605.GB2061@intel.com>
Date:   Sat, 3 Sep 2016 09:26:05 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:     Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        "moderated list:TPM DEVICE DRIVER" 
        <tpmdd-devel@...ts.sourceforge.net>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tpm: move struct tpm_class_ops to drivers/char/tpm/tpm.h

On Sat, Sep 03, 2016 at 09:22:21AM +0300, Jarkko Sakkinen wrote:
> On Fri, Sep 02, 2016 at 04:45:31PM -0600, Jason Gunthorpe wrote:
> > On Sat, Sep 03, 2016 at 01:35:22AM +0300, Jarkko Sakkinen wrote:
> > > On Fri, Sep 02, 2016 at 04:11:22PM -0600, Jason Gunthorpe wrote:
> > > > On Sat, Sep 03, 2016 at 12:48:03AM +0300, Jarkko Sakkinen wrote:
> > > > > The struct tpm_class_ops is not used outside the TPM driver. Thus,
> > > > > it can be safely move to drivers/char/tpm/tpm.h.
> > > > 
> > > > No, this is the wrong direction.
> > > > 
> > > > The goal is to make things more like other subsystems, so we should be
> > > > moving struct tpm_chip into the public header, and that requires ops
> > > > to be in the public header.
> > > > 
> > > > This is why I put ops here in the first place.
> > > 
> > > I'm OK with it as long as you explain why this is necessary. I see no
> > > use for them outside the TPM subsystem.
> > 
> > That is because the users out side the subsystem are Doing it Wrong.
> > 
> > eg this:
> > 
> >  extern int tpm_is_tpm2(u32 chip_num);
> > 
> > Should be:
> > 
> >  extern int tpm_is_tpm2(struct tpm_chip *chip);
> > 
> > And same for all other examples.
> > 
> > The 'chip_num' thing is bonkers.
> 
> OK, how would one get the chip instance?

This still doesn't explain why moving the structures inside the driver
would be wrong. Even if outside callers would use a pointer the
structure could be opaque.

/Jarkko