linux-kernel - Re: [PATCH 3/3] vTPM: support little endian guests

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: <1431126624.25419.11.camel@vtpm2014.ibm.com>
Date:	Fri, 08 May 2015 19:10:24 -0400
From:	"Hon Ching (Vicky) Lo" <honclo@...ux.vnet.ibm.com>
To:	Ashley Lai <ashley@...leylai.com>
Cc:	tpmdd-devel@...ts.sourceforge.net, Peter Huewe <PeterHuewe@....de>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Vicky Lo <honclo2014@...il.com>, linux-kernel@...r.kernel.org,
	Joy Latten <jmlatten@...ux.vnet.ibm.com>
Subject: Re: [PATCH 3/3] vTPM: support little endian guests

Thanks Ashley!

> > The event log in ppc64 arch is always in big endian format. PowerPC
> > supports both little endian and big endian guests. This patch converts
> > the event log entries to guest format.
> 
> I'm a little confused here.  If this patch is to convert the event log 
> entries why are we convert in the conditional statements?  One example 
> below:
> 
> +       if (((convert_to_host_format(event->event_type) == 0) &&
> +            (convert_to_host_format(event->event_size) == 0))
> +           ||
> +           ((v + sizeof(struct tcpa_event) +
> +             convert_to_host_format(event->event_size)) > limit))
> 
> >
> > We defined a macro to convert to guest format. In addition,
> > tpm_binary_bios_measurements_show() is modified to parse the event
> > and print each field individually.
> 

We do not convert the whole event entry.  Instead, we're converting only
what's necessary such as pcr_index, event_type and event_size. pcr_value
and event_data are of type u8.  They do not need LE conversion.


> It's nice to have human readable format but it may break existing tools 
> that parse or understand the machine readable format.  Any comments on 
> this anyone?

I got comments on the format, so I tried to make that conditional
statement all in one line, but the 'Lindent' tool puts the lines back to
the above format..   


Regards,
Vicky

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/