> Without that practical reason, I think the only two sane sealing operations are: > > - SEAL_MUNMAP: "don't allow this mapping address to go away" > > IOW no unmap, no shrinking, no moving mremap > > - SEAL_MPROTECT: "don't allow any mapping permission changes" > > Again, that permission case might end up being "don't allow > _additional_ permissions" and "don't allow taking permissions away". > Or it could be split by operation (ie "don't allow permission changes > to writability / readability / executability respectively"). > > I suspect there isn't a real-life example of splitting the > SEAL_MPROTECT (the same way I doubt there's a real-life example for > splitting the UNMAP into "unmap vs move"), so unless there is some > real reason, I'd keep the sealing minimal and to just those two flags. These two flags are exactly what we would use in Chrome. I can't think of a use case for a more fine grained split either.
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