Messages in this thread | | | Subject | Re: [RFC] /dev/ioasid uAPI proposal | From | Paolo Bonzini <> | Date | Wed, 9 Jun 2021 11:11:17 +0200 |
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On 09/06/21 10:51, Enrico Weigelt, metux IT consult wrote: > On 08.06.21 21:00, Jason Gunthorpe wrote: > >> Eg I can do open() on a file and I get to keep that FD. I get to keep >> that FD even if someone later does chmod() on that file so I can't >> open it again. >> >> There are lots of examples where a one time access control check >> provides continuing access to a resource. I feel the ongoing proof is >> the rarity in Unix.. 'revoke' is an uncommon concept in Unix.. > > Yes, it's even possible that somebody w/ privileges opens an fd and > hands it over to somebody unprivileged (eg. via unix socket). This is > a very basic unix concept. If some (already opened) fd now suddenly > behaves differently based on the current caller, that would be a break > with traditional unix semantics.
That's already more or less meaningless for both KVM and VFIO, since they are tied to an mm.
Paolo
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