linux-kernel - Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list

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Date:	Wed, 10 Aug 2016 13:41:08 +1000
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	linux-security-module@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-ima-devel@...ts.sourceforge.net,
	Dave Young <dyoung@...hat.com>
Subject: Re: [PATCH 1/7] ima: on soft reboot, restore the measurement list

Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com> writes:

> Am Dienstag, 09 August 2016, 09:01:13 schrieb Mimi Zohar:
>> On Tue, 2016-08-09 at 20:59 +1000, Michael Ellerman wrote:
>> > Mimi Zohar <zohar@...ux.vnet.ibm.com> writes:
>> > > diff --git a/security/integrity/ima/ima.h
>> > > b/security/integrity/ima/ima.h
>> > > index b5728da..84e8d36 100644
>> > > --- a/security/integrity/ima/ima.h
>> > > +++ b/security/integrity/ima/ima.h
>> > > @@ -102,6 +102,13 @@ struct ima_queue_entry {
>> > > 
>> > >  };
>> > >  extern struct list_head ima_measurements;	/* list of all 
> measurements
>> > >  */
>> > > 
>> > > +/* Some details preceding the binary serialized measurement list */
>> > > +struct ima_kexec_hdr {
>> > > +	unsigned short version;
>> > > +	unsigned long buffer_size;
>> > > +	unsigned long count;
>> > > +} __packed;
>> > > +
>> > 
>> > Am I understanding it correctly that this structure is passed between
>> > kernels?
>> Yes, the header prefixes the measurement list, which is being passed on
>> the same computer to the next kernel.  Could the architecture (eg.
>> LE/BE) change between soft re-boots?
>
> Yes. I am able to boot a BE kernel from an LE kernel with my patches. 
> Whether we want to support that or not is another question...

Yes you must support that. BE -> LE and vice versa.

You should also consider the possibility that the next kernel is not
Linux.

cheers