Messages in this thread | | | Date | Mon, 2 Jul 2007 12:00:43 -0700 | From | Andy Isaacson <> | Subject | Re: [patch 0/4] MAP_NOZERO v2 - VM_NOZERO/MAP_NOZERO early summer madness |
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On Sat, Jun 30, 2007 at 08:21:52PM -0400, Kyle Moffett wrote: > That's why you'd need to call an LSM hook to get a unique identifier, > as the LSM would actually need to allocate identifiers for > equivalence classes. Secondly, processes may change labels as they > run, so you couldn't just call it once and cache the result, you > would need to call it for every freed page (or every re-use of a page).
Davide's patch adds a owner_uid field to mm_struct. Assuming that turns into a "mm security equivalence class identifier", the LSM can simply update it when a label-change-event occurs. No need to call out to (potentially heavyweight!) LSM code in page allocation critical paths.
I'm a bit concerned that tracking the equivalence classes will get expensive. I think you can end up with quadratic explosion in the worst case (every user using every permutation of LSM bits).
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