Re: Providing qemu-guest-agent in our images
21.02.2019 0:08, Marco d'Itri wrote:
On Feb 20, Michael Tokarev <mjt@tls.msk.ru> wrote:
...
Looks like I was looking at an old version then: now I have installed
the buster version and it's there.
Blacklist functionality has been in qga for a very long time,
Debian includes it since long time too. But okay.
Speaking of a qemu-ga blacklist, -- well, from the host side of view
such a blacklist is more or less pointless, since host can even trace
every cpu instruction a guest does, if host wants to see files on the
guest it's not a problem at all, it have full access to everything.
Sure, as long it does not use a modern AMD CPU with encrypted memory,
but still I think that there is a big difference between peeking at RAM
and accessing everything with an handy API.
In order to setup encrypted memory you have to do some steps, I guess
it's done on both host and guest, and still it is very difficult to
do it in a way so that host can't see it.
Besides peeking at RAM you can see hdd images (can also be encrypted
but this is still one extra layer, also hackable from host).
From my PoV, speaking of hosting (virtual or not), you either have to
trust your provider or run your own physical machine.
What blacklist is "sensible" from your PoV?
By default it should prevent information leak from the guest.
guest-file-open
guest-file-close
guest-file-read
guest-file-write
guest-file-seek
guest-file-flush
guest-get-memory-blocks
guest-set-memory-blocks
guest-get-memory-block-info
guest-exec-status
guest-exec
I disagree completely. It is a usability vs security issue really.
For a typical "home/office" use the easier the better, and there's
no need to protect guest from host since both are run by the same
people, or "host" people can be "more trusted" than "guest" people.
When you actually have ability to protect guest from host (encrypted
memory has already been mentioned), which is actually really rare,
you can provide whatever blacklist you think is safe for you.
If we're to provide some default blacklist, I think we can at least
try to discuss it upstream or between several distributions, which
is better. To me it makes very very little real sense.
Thanks,
/mjt
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