linux-kernel - Re: [PATHC v2 5/9] ima: on soft reboot, save the measurement list

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Message-Id: <1472822579.3669.13.camel@linux.vnet.ibm.com>
Date:   Fri, 02 Sep 2016 09:22:59 -0400
From:   Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:     Dave Young <dyoung@...hat.com>
Cc:     linux-security-module <linux-security-module@...r.kernel.org>,
        Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>,
        linux-ima-devel@...ts.sourceforge.net, kexec@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATHC v2 5/9] ima: on soft reboot, save the measurement list

Hi Dave,

On Thu, 2016-09-01 at 09:57 +0800, Dave Young wrote:
> On 08/30/16 at 06:40pm, Mimi Zohar wrote:

> > + * Called during kexec_file_load so that IMA can add a segment to the kexec
> > + * image for the measurement list for the next kernel.
> > + */
> > +void ima_add_kexec_buffer(struct kimage *image)
> > +{
> > +	static int registered = 0;
> > +	struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE,
> > +				  .buf_min = 0, .buf_max = ULONG_MAX,
> > +				  .top_down = true, .skip_checksum = true };
> > +	int ret;
> > +
> > +	if (!kexec_can_hand_over_buffer())
> > +		return;
> > +
> > +	kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + PAGE_SIZE,
> > +				   PAGE_SIZE);
> > +
> > +	if (kexec_segment_size >= (ULONG_MAX - sizeof(long))) {
> > +		pr_err("Binary measurement list too large.\n");
> > +		return;
> > +	}
> 
> Now we added a limitation that total segment size can not be larger than
> half of totalram. see kernel/kexec_core.c sanity_check_segment_list()
> 
> So can it fail early here if kexec_segment_size is over half of total
> ram?

Sure, I'll include this change in the next post.

Mimi