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authorFrancis Rowe <info@gluglug.org.uk>2015-08-23 11:22:34 (EDT)
committer Francis Rowe <info@gluglug.org.uk>2015-08-23 11:22:34 (EDT)
commit619b04be938c0bd0fb040ddfd437abb72b6bce6a (patch)
treeada0d053a61448ad3587abc53835f3fab9f1fc01
parent730ba63e485a6755fb1dd85e5654ce2cfb1a4834 (diff)
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FAQ: mitigations for certain DMA-capable hardware
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@@ -478,7 +478,8 @@
unencrypted for future retrieval by an adversary.
</p>
<p>
- With proper IOMMU, it might be possible to mitigate the DMA-related issues.
+ With proper IOMMU, it might be possible to mitigate the DMA-related issues. USB drives (flash drive, HDD, etc) can be used,
+ to avoid DMA.
</p>
<p>
Some proof of concepts have been demonstrated. For HDDs:<br/>
@@ -500,6 +501,7 @@
</p>
<p>
With proper IOMMU, it might be possible to mitigate the DMA-related issues.
+ A USB NIC can also be used, which does not have DMA.
</p>
<p>
<a href="#pagetop">Back to top of page</a>
@@ -513,6 +515,11 @@
Microcode can be very powerful. No proof that it's malicious, but it could theoretically
</p>
<p>
+ There isn't really a way to solve this, unless you use a CPU which does not have microcode.
+ (ARM CPUs don't, but most ARM systems require blobs for the graphics hardware at present, and typically
+ have other things like soldered wifi which might require blobs)
+ </p>
+ <p>
CPUs often on modern systems have a processor inside it for things like power management.
ARM for example, has lots of these.
</p>
@@ -523,6 +530,7 @@
<h3 id="firmware-sound">Sound card <span class="ref">(<a href="#firmware-sound">#firmware-sound</a>)</h3>
<p>
Sound hardware (integrated or discrete) typically has firmware on it (DSP) for processing input/output.
+ Again, a USB DAC is a good workaround.
</p>
<p>
<a href="#pagetop">Back to top of page</a>
@@ -531,7 +539,8 @@
<h3 id="firmware-webcam">Web cam <span class="ref">(<a href="#firmware-webcam">#firmware-webcam</a></h3>
<p>
Webcams have firmware integrated into them that process the image input into the camera; adjusting focus,
- white balancing and so on.
+ white balancing and so on. Can use USB webcam hardware, to work around potential DMA issues; integrated webcams
+ (on laptops, for instance) are discouraged by the libreboot project.
</p>
<p>
<a href="#pagetop">Back to top of page</a>