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

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Message-ID: <20160810154849.GE4087@localhost>
Date:	Wed, 10 Aug 2016 18:48:49 +0300
From:	Petko Manolov <petkan@...-labs.com>
To:	David Laight <David.Laight@...LAB.COM>
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>,
	"linux-security-module@...r.kernel.org" 
	<linux-security-module@...r.kernel.org>,
	"linux-ima-devel@...ts.sourceforge.net" 
	<linux-ima-devel@...ts.sourceforge.net>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [Linux-ima-devel] [PATCH 1/7] ima: on soft reboot, restore the
 measurement list

On 16-08-10 14:40:13, David Laight wrote:
> From: Linuxppc-dev [mailto:linuxppc-dev-bounces+david.laight=aculab.com@...ts.ozlabs.org] On Behalf Of
> > > > So given what you have above, you'd use something like:
> > > >
> > > > struct ima_kexec_hdr {
> > > > 	u16 version;
> > > > 	u16 _reserved0;
> > > > 	u32 _reserved1;
> > > > 	u64 buffer_size;
> > > > 	u64 count;
> > > > };
> > > >
> > > > cheers
> > >
> > > Thanks, I'll make this change.
> > 
> > I would suggest:
> > 
> > struct ima_kexec_hdr {
> > 	u64 buffer_size;
> > 	u64 count;
> > 	u16 version;
> > };
> > 
> > and let the compiler add the proper padding, depending on the architecture.  On
> > 32bit machine we'll have 4 bytes smaller allocations (compared to 64bit) while
> > retaining the same functionality.
> 
> AAAArrrrgggg.....
> 
> That doesn't work for 32bit applications on 64bit hosts.

Which part won't work?

> The extra bytes will make 0 difference to the allocation cost and lots to the 
> processing.

An example?


		Petko