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Not really "working"
Posted Jul 16, 2009 16:33 UTC (Thu) by pr1268 (subscriber, #24648)
From Dave's blog:
...granted it oopses soon afterwards...
Doesn't sound like "working" to me. Just my skeptical $0.02.
(Not meant to impugn the work of the Moblin devs and Dave A.)
Posted Jul 16, 2009 17:14 UTC (Thu) by jsbarnes (guest, #4096)
Anyway Dave definitely deserves a lot of credit here; not only did he do some of this last year, he also wrote most of the kernel mode setting code which made it possible.
Posted Jul 17, 2009 16:32 UTC (Fri) by i3839 (guest, #31386)
Avoiding informationa leakage, especially keyboard input, seems like a difficult problem. Easiest seems for the kernel to stop sending data to already open file descriptors when permissions or ownership change. It's unclear how userspace could handle this without help.
Posted Jul 17, 2009 17:29 UTC (Fri) by jsbarnes (guest, #4096)
I think we still need to work on the DRM master/auth scheme though, maybe allowing set/drop master to be an unprivileged call (only allowing one master of course).
Posted Jul 18, 2009 9:59 UTC (Sat) by i3839 (guest, #31386)
That doesn't seem safe because it is very racy. E.g. two malicious processes ping-pong the fd via unix domain sockets. With some bad luck you either kill the wrong one or don't see the fd at all. Alternative race is dup2'ing the fd around, or simply doing a fork() at the right time.
This also needs root access, which is needed to do ownership changes anyway, but unlike changing ownership chasing processes and killing them is tricky and dangerous. Interesting exploit: Somehow letting a root process open an input device (e.g. via a symlink) and let it get killed.
Please don't go that way, it will cause problems.
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