Chris Laprise: > On 04/02/2017 03:42 AM, Vít Šesták wrote: >> Yes, disabling those features can prevent thise threats. But I wonder >> if Qubes does this by default or if I can disable it manually. > > We may want to open an issue for this, or at least a thread in > qubes-developer. > > >> >> I have also an idea how to disable it, but I am unsure if it will >> work properly: Connect laptop HDMI port -> HDMI to DVI -> DVI to >> HDMI -> TV HDMI port. But since no conversion is needed, you might >> end up with full HDMI connection. >> >> Related quotation: “HDMI implements the EIA/CEA-861 standards, which >> define video formats and waveforms, transport of *compressed*, >> uncompressed, and LPCM audio, auxiliary data, and implementations of >> the VESA EDID.[5][6](p. III) *CEA-861 signals carried by HDMI are >> electrically compatible with the CEA-861 signals used by the digital >> visual interface (DVI). No signal conversion is necessary*, nor is >> there a loss of video quality when a DVI-to-HDMI adapter is >> used.[6](§C)” (https://en.m.wikipedia.org/wiki/HDMI, emphasis is >> mine) > > I don't believe this means that HDMI features carry over to DVI outputs > on computers, just that HDMI ports can output to DVI displays. But it > would be good to know what an HDMI-capable monitor can do, for instance, > if a DVI-only card is plugged into one of its DVI ports. > >> >> My notes on this: >> >> 1. Compressed audio is not what I want for Audio return channel :(. >> 2. The [6](§C) links to Appendix C of HDMI spec (see >> http://www.microprocessor.org/HDMISpecification13a.pdf ), which >> defines *bidirectional* compatibility level between HDMI and DVI. >> >> Regards, Vít Šesták 'v6ak' >> > > If the compression is only in one direction (out to the display) then I > don't think it matters... or its a feature you want to keep. > > What we need is a breakdown of the supported protocols along with a > description of their interactivity and flow. >
It's a bit impractical, but how about an HDMI firewall? A Pynq-Z1 board can be had fairly cheap ($230 normally, $65 for students), and implementing a dumb framebuffer copy with simple open-source components is just a matter of ~10 lines of Python. Github: https://github.com/Xilinx/PYNQ Board shop: http://store.digilentinc.com/pynq-z1-python-productivity-for-zynq/ Documentation doing exactly this: https://pynq.readthedocs.io/en/latest/9_base_overlay_video.html (no affiliation with any of the above) Andrew -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to qubes-users+unsubscr...@googlegroups.com. To post to this group, send email to qubes-users@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/41bac81e-9d61-9bd0-16d2-4193cde71ca9%40riseup.net. For more options, visit https://groups.google.com/d/optout.
