lkml.org 
[lkml]   [2017]   [Aug]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCHv3 2/2] extract early boot entropy from the passed cmdline
On Wed 2017-08-16 23:31:48, Theodore Ts'o wrote:
> On Wed, Aug 16, 2017 at 04:14:58PM -0700, Laura Abbott wrote:
> > From: Daniel Micay <danielmicay@gmail.com>
> >
> > Existing Android bootloaders usually pass data useful as early entropy
> > on the kernel command-line. It may also be the case on other embedded
> > systems.....
>
> May I suggest a slight adjustment to the beginning commit description?
>
> Feed the boot command-line as to the /dev/random entropy pool
>
> Existing Android bootloaders usually pass data which may not be
> known by an external attacker on the kernel command-line. It may
> also be the case on other embedded systems. Sample command-line
> from a Google Pixel running CopperheadOS....
>
> The idea here is to if anything, err on the side of under-promising
> the amount of security we can guarantee that this technique will
> provide. For example, how hard is it really for an attacker who has
> an APK installed locally to get the device serial number? Or the OS
> version? And how much variability is there in the bootloader stages
> in milliseconds?
>
> I think we should definitely do this. So this is more of a request to
> be very careful what we promise in the commit description, not an
> objection to the change itself.

The command line is visible to unpriviledged userspace (/proc/cmdline,
dmesg). Is that a problem?

U-boot already does some crypto stuff, so it may have some
randomness. Should we create parameter random=xxxxxxxxxxx that is
"censored" during kernel boot?

Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2017-08-30 11:58    [W:0.118 / U:0.832 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site