linux-kernel - RE: [PATCH v9 07/17] platform/x86: dell-smbios: only run if proper oem string is detected

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Message-ID: <811c84e436424acaba9a02186db00cf8@ausx13mpc120.AMER.DELL.COM>
Date:   Tue, 17 Oct 2017 19:19:02 +0000
From:   <Mario.Limonciello@...l.com>
To:     <pali.rohar@...il.com>
CC:     <dvhart@...radead.org>, <andy.shevchenko@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>, <luto@...nel.org>,
        <quasisec@...gle.com>, <rjw@...ysocki.net>, <mjg59@...gle.com>,
        <hch@....de>, <greg@...ah.com>, <gnomes@...rguk.ukuu.org.uk>
Subject: RE: [PATCH v9 07/17] platform/x86: dell-smbios: only run if proper
 oem string is detected

> -----Original Message-----
> From: Limonciello, Mario
> Sent: Tuesday, October 17, 2017 2:11 PM
> To: 'Pali Rohár' <pali.rohar@...il.com>
> Cc: dvhart@...radead.org; Andy Shevchenko <andy.shevchenko@...il.com>;
> LKML <linux-kernel@...r.kernel.org>; platform-driver-x86@...r.kernel.org; Andy
> Lutomirski <luto@...nel.org>; quasisec@...gle.com; rjw@...ysocki.net;
> mjg59@...gle.com; hch@....de; Greg KH <greg@...ah.com>; Alan Cox
> <gnomes@...rguk.ukuu.org.uk>
> Subject: RE: [PATCH v9 07/17] platform/x86: dell-smbios: only run if proper oem
> string is detected
> 
> > -----Original Message-----
> > From: Pali Rohár [mailto:pali.rohar@...il.com]
> > Sent: Tuesday, October 17, 2017 2:04 PM
> > To: Limonciello, Mario <Mario_Limonciello@...l.com>
> > Cc: dvhart@...radead.org; Andy Shevchenko <andy.shevchenko@...il.com>;
> > LKML <linux-kernel@...r.kernel.org>; platform-driver-x86@...r.kernel.org;
> Andy
> > Lutomirski <luto@...nel.org>; quasisec@...gle.com; rjw@...ysocki.net;
> > mjg59@...gle.com; hch@....de; Greg KH <greg@...ah.com>; Alan Cox
> > <gnomes@...rguk.ukuu.org.uk>
> > Subject: Re: [PATCH v9 07/17] platform/x86: dell-smbios: only run if proper oem
> > string is detected
> >
> > On Tuesday 17 October 2017 13:21:51 Mario Limonciello wrote:
> > > The proper way to indicate that a system is a 'supported' Dell System
> > > is by the presence of this string in OEM strings.
> > >
> > > Allowing the driver to load on non-Dell systems will have undefined
> > > results.
> > >
> > > Signed-off-by: Mario Limonciello <mario.limonciello@...l.com>
> > > Reviewed-by: Edward O'Callaghan <quasisec@...gle.com>
> > > ---
> > >  drivers/platform/x86/dell-smbios.c | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > >
> > > diff --git a/drivers/platform/x86/dell-smbios.c b/drivers/platform/x86/dell-
> > smbios.c
> > > index e9b1ca07c872..7e779278d054 100644
> > > --- a/drivers/platform/x86/dell-smbios.c
> > > +++ b/drivers/platform/x86/dell-smbios.c
> > > @@ -172,8 +172,15 @@ static void __init find_tokens(const struct dmi_header
> > *dm, void *dummy)
> > >
> > >  static int __init dell_smbios_init(void)
> > >  {
> > > +	const struct dmi_device *valid;
> > >  	int ret;
> > >
> > > +	valid = dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "Dell System",
> > NULL);
> >
> > Are you sure that all Dell machines have exactly this string? IIRC this
> > smbios interface via SMM is supported by machines back to 2005... Also
> > in other DMI tables in dell-latop there is e.g. "Dell Inc." or "Dell
> > Computer Corporation".
> >
> I checked the spec and it's been there since systems 1999 onward.
> 

Oh and it's case it's not apparent, this is from OEM strings section.  It's not
the same as standard SMBIOS strings for system manufacturer, bios vendor
etc.  I'm checking this one specifically because a system can be rebranded.  
When rebranded the drivers won't load automatically, but this interface 
should still work on a if manually loaded.