[Replicant] [PATCH 5/9] freedom-privacy-security-issues: Free hardware do exist today.

[Paul Kocialkowski]

Le mercredi 02 mars 2016 à 20:28 +0100, Denis 'GNUtoo' Carikli a écrit :
> Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo at no-log.org>

Subject has a grammar mistake: hardware is singular so it should be "does
exist".

Free hardware means a fully free hardware design (both at pcb and chip levels).
I don't know of any mobile devices that fits the chip-level hardware freedom
requirement, so I think it's fair to say that free hardware doesn't exist in the
scope of mobile devices.

Perhaps the current version should contain this analysis, emphasis that it's
about mobile devices. Also it should contrast with the rest about hardware
freedom not being a practical possibility for most people.

> ---
>  freedom-privacy-security-issues.php | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/freedom-privacy-security-issues.php b/freedom-privacy-security-
> issues.php
> index 65fc54a..31d8310 100644
> --- a/freedom-privacy-security-issues.php
> +++ b/freedom-privacy-security-issues.php
> @@ -10,7 +10,7 @@
>  			<p>Regarding the software side of things on mobile
> devices, the main CPU (inside the SoC) starts by executing code located inside
> the silicon. If this is an ARM CPU, that code will be ARM instructions. This
> code is known as the botrom. It will look up various places such as NAND, eMMC
> or MMC (sd/micro sd card) storage, depending on the hardware configuration, to
> load a bootloader. The bootloader, which is in fact often split in different
> stages, is in charge of bringing up and configuring various aspects of the
> hardware and eventually starting the operating system by loading and running
> its kernel.<br /><a href="images/freedom-privacy-security-
> issues/software.png" 
> data-lightbox="overview" data-title="Software-side overview"><img
> src="images/freedom-privacy-security-issues/software.png" alt="Software-side
> overview" style="width: 250px; float: right;"/></a>The kernel itself, among
> other things, deals with the hardware directly and provides ways for other
> programs (running in user-s
>  pace) to access it. In user-space, hardware abstraction layers are programs
> specific to each device that know how to properly drive the hardware. They use
> the kernel to communicate back and forth with the hardware and implement the
> proper protocols for it.<br /><br />The actual knowledge of how to drive the
> hardware is split between the kernel and the hardware abstraction layer
> libraries: both are needed to make it work properly. Hardware abstraction
> layers provide a generic interface for the framework to use. The framework
> itself provides an interface for applications that is independent of the
> device and the hardware. That way, applications can access hardware features
> through the generic framework interface, which will call the hardware
> abstraction layer libraries, ending up with the kernel communicating with the
> hardware. For instance, when making a call, the dialer application will
> communicate with the framework, which in turn will communicate with the
> hardware abstraction laye
>  r. That hardware abstraction layer will implement the protocol to speak with
> the modem, and the Linux kernel will be responsible of permitting the
> communication between the hardware abstraction layer and the modem.</p>
>  			<p>Many other components of a mobile device also run
> software in different forms. The various integrated circuits run small pieces
> of dedicated software that are called firmwares. When the device is telephony-
> enabled, there is also software running on the modem. Modern modems are
> complex and run full operating systems.</p>
>  			<h3>The current situation of freedom and
> privacy/security on mobile devices</h3>
> -			<p>A mobile device respecting the users' freedom
> would have:<ul><li>Free hardware</li><li>Free firmwares</li><li>Free modem
> system</li><li>Free bootrom and bootloader</li><li>Free system and
> applications</li></ul>Regarding <a href="#free-hardware">free hardware</a>, it
> doesn't quite exist as of today, or barely. Modifying hardware is nearly
> impossible: new versions of the hardware have to be produced, and those are
> expensive. While producing printed circuit boards (PCBs) costs a lot of money,
> producing integrated circuits is out of reach. A few devices come with
> schematics for the PCB, but that's usually as far as it gets. Hence, totally-
> free hardware doesn't exist yet.</p>
> +			<p>A mobile device respecting the users' freedom
> would have:<ul><li>Free hardware</li><li>Free firmwares</li><li>Free modem
> system</li><li>Free bootrom and bootloader</li><li>Free system and
> applications</li></ul>Regarding <a href="#free-hardware">free hardware</a>, it
> barely exist as of today. Modifying hardware is nearly impossible: new
> versions of the hardware have to be produced, and those are expensive. While
> producing printed circuit boards (PCBs) costs a lot of money, producing
> integrated circuits is out of reach. A few devices come with schematics for
> the PCB, but that's usually as far as it gets. Hence, totally-free hardware
> doesn't exist yet.</p>
>  			<p>Firmwares running inside integrated circuits are
> most of the time proprietary. While free firmwares are hard to write, some
> exist for very specific hardware (e.g. <a href="//www.arduino.cc/">Arduino</a>
> ;
> ;, <a href="//dangerousprototypes.com/docs/Bus_Pirate">Bus Pirate</a>) and
> sometimes,  manufacturers can liberate firmwares running in their integrated
> circuits (e.g. <a href="//github.com/qca/open-ath9k-htc-
> firmware">ath9k_htc</a>). However, it is not always possible to even replace
> those firmwares: some are loaded to the integrated circuit by the main CPU but
> some others are pre-installed in the circuit (in that case, they almost seem
> to behave like hardware) and cannot be updated to a free replacement.</p>
>  			<p><a href="images/freedom-privacy-security-
> issues/bad-modem-isolation.png" data-lightbox="current-situation" data-
> title="Bad modem isolation"><img src="images/freedom-privacy-security-
> issues/bad-modem-isolation.png" alt="Bad modem isolation" style="width: 250px;
> float: left;"/></a>The modem system on telephony-enabled mobile devices is
> always proprietary. While <a href="//bb.osmocom.org/">OsmocomBB</a>, a free
> software GSM stack exists, it only runs on old feature phones, currently
> requires a host computer to operate and is not certified to run on public
> networks. Despite this situation, the modem remains a crucial part for
> privacy/security: it is nearly always connected to the GSM network, allowing
> for <a href="//www.gnu.org/philosophy/malware-mobiles.html">remote
> control</a>. The modem can be more or less damaging to privacy/security
> depending on what hardware it has access to and can control. That is to say,
> how isolated it is from the rest of the device.<br /><br />A device 
>  with bad modem isolation would allow the modem to access and control key
> parts of the hardware, such as the RAM, storage, GPS, camera, user I/O and
> microphone. This situation is terrible for privacy/security as it provides
> plenty of ways to efficiently spy on the user, triggered remotely over the
> mobile telephony network. Those are accessible to the mobile telephony
> operator, but also to attackers setting up fake base stations for that
> purpose. <a href="images/freedom-privacy-security-issues/good-modem-
> isolation.png" data-lightbox="current-situation" data-title="Good modem
> isolation"><img src="images/freedom-privacy-security-issues/good-modem-
> isolation.png" alt="Good modem isolation" style="width: 250px; float:
> right;"/></a>On the other hand, when the modem is well-isolated from the rest
> of the device, it is limited to communicating directly with the SoC and can
> only access the device's microphone when allowed by the SoC. It is then
> strictly limited to accessing what it really needs
>  , which considerably reduces its opportunities to spy on the user. While it
> doesn't solve any of the freedom issues, having an isolated modem is a big
> step forward for privacy/security. However, it is nearly impossible to be
> entirely sure that the modem is actually isolated, as any documentation about
> the device cannot be trusted, due to the lack of effective hardware freedom.
> On the other hand, it is possible to know that the modem is not isolated, when
> there is proof that it can access hardware that could be used to spy on the
> user.</p>
>  			<p>Looking at the software that runs early on the
> SoC, the first component is the bootrom. It is always proprietary and is
> stored in read-only memory, so it cannot be changed (in that case, it almost
> seems to behave like hardware). However, regarding the bootloader, the
> situation is different for each platform. There are actually multiple stages
> of bootloaders, some of which can be free. However, it also occurs that the
> bootloaders are cryptographically signed with a private key. In that case, the
> bootrom will check the signature against a public key that cannot be replaced
> and only run the bootloader if the signature matches. That sort of tivoization
> prevents replacing pre-installed bootloaders, even when their sources are
> released as free software. There are some good platforms that don't perform
> such signature checks and can run free bootloaders (e.g. Allwinner Ax, TI OMAP
> General-Purpose).</p>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: This is a digitally signed message part
URL: <http://lists.osuosl.org/pipermail/replicant/attachments/20160303/b3252cd7/attachment.asc>