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[Xen-devel] Is exposing shared_info to user-land secure?

  • To: "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
  • Date: Fri, 1 Aug 2008 10:13:39 -0600
  • Delivery-date: Fri, 01 Aug 2008 09:15:13 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: Acjz8Y15ey1z2oZsTGWTFL6iUZbGKg==

Is it "safe" in a paravirtualized guest to expose shared_info
(at least read-only) to user-land?  That is, is there data
in shared_info that could be used by a malicious program to
compromise a guest OS (ignoring very complex side-channel
attacks anyway)?

We have apps that constantly do various time syscalls (e.g.
to gettimeofday()) and I'm thinking if vcpu_info(cpu)->time_info
was directly readable by an enterprise app, it could do
the time calculations itself and save the syscall overhead.



Thanks... for the memory
I really could use more / My throughput's on the floor
The balloon is flat / My swap disk's fat / I've OOM's in store
Overcommitted so much
(with apologies to the late great Bob Hope)
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