On Thu, 2017-06-15 at 14:22 +0200, Andrew 👽 Yourtchenko wrote: > After a bit more thinking - there is a way that should take care of both: > > 1) What Chris wrote: have consistent behaviour with non-existent ACL > as if the ACL matching fell off the end of the ACL: if an empty ACL is > referenced, treat it as if it had entries but none of them had > matched. Then we still hit the "default deny" if none of the applied > ACLs match, and drop the packets - so it will be logical. > > 2) What Marco wrote: when deleting an already referenced ACL, unapply > it from all the places where it is applied. > > It's a change in the behaviour in that the current behaviour is to > have the empty ACL act as if it was "deny any any", and block the > matching even if there is another ACL after it - but on the other hand > this would take both viewpoints in mind... I think this approach would still leave the system in an inconsistent state: an interface is basically assigned an ACL which does not exist in the system. Also, the risk I see is if I later on create an ACL with the previously used index then an interface would see that ACL being applied automatically (since it's referenced). However, I may not want to have that ACL assigned to that particular interface. Correct?
I think that the "deletion" of an ACL could see one of the two behaviours below: 1) the deletion of an ACL should be DENIED if that ACL is assigned to any interface (probably the easier and safer approach); 2) the deletion of an ACL should see a CASCADING effect onto the interfaces which would be "cleaned up" of any references to that ACL; I think (1) is a very good way of solving the initial problem since it works nicely if you manage VPP directly (e.g. via command-line) and if you use a controller. In the latter, the controller can react on the "error" returned by the acl_del API because that ACL is assigned somewhere. Cheers, Marco > > What do you think ? > > --a > > On 6/9/17, Andrew 👽  Yourtchenko <ayour...@gmail.com> wrote: > > > > Assuming the only change is to effectively have > > "unbind_acl_from_everywhere; delete_acl" instead of "delete_acl", > > maybe it would be best to tackle that post-17.07 with a separate API > > message acl_del_and_unbind or similar ? > > > > I feel a beet wary of adding more hidden state (even though the > > reflected sessions table does provide already plenty of it :) > > > > --a > > > > On 6/9/17, Luke, Chris <chris_l...@comcast.com> wrote: > > > > > > Would it make sense to have a flag on the interface (or globally), set > > > when > > > applying the ACL, that indicates the desired behavior when the ACL is > > > empty > > > or non-existent? At the moment to me it seems logical that this is the > > > same > > > behavior as when matching falls off the end of the ACL. > > > > > > Chris. > > > > > > > > > > > -----Original Message----- > > > > From: vpp-dev-boun...@lists.fd.io [mailto:vpp-dev-boun...@lists.fd.io] > > > > On > > > > Behalf Of Andrew ?? Yourtchenko > > > > Sent: Friday, June 9, 2017 7:53 > > > > To: Marco Varlese <marco.varl...@suse.com> > > > > Cc: vpp-dev@lists.fd.io > > > > Subject: Re: [vpp-dev] Bind / Unbind of ACL > > > > > > > > Hi Marco, > > > > > > > > Yes, this works as expected, assuming after deletion *all* the traffic > > > > is > > > > denied, rather than just the SSH traffic. > > > > > > > > If you apply to an interface the ACL# that does not exist, that is the > > > > same as if > > > > there was an ACL with just the "deny all" semantics, to avoid the > > > > perception > > > > that a given policy is enforced when it isn't - so I erred on the side > > > > of > > > > caution. > > > > > > > > The way to remove the ACL: you would ensure the ACL is not applied to > > > > the > > > > interface(s) first, then remove the ACL (or replace it with a different > > > > policy in- > > > > place). > > > > > > > > Alternatively, you can just replace the existing ACL in-place with > > > > "permit > > > > any" > > > > for IPv4 and IPv6 - this way you explicitly state that there is a policy > > > > to permit > > > > all the traffic. > > > > > > > > I've been bitten myself and seen several times in my career when an > > > > applied > > > > but non-existent ACL caused problems later on, in the worst possible > > > > moment. The current behaviour IMHO makes the config discrepancy clear - > > > > what do you think ? > > > > > > > > --a > > > > > > > > On 6/9/17, Marco Varlese <marco.varl...@suse.com> wrote: > > > > > > > > > > Hi, > > > > > > > > > > I am trying the ACL functionality and I found a "strange" behaviour. > > > > > > > > > > The steps I follow to use an ACL are: > > > > > * I create an ACL to deny SSH traffic between VMs (via the > > > > 'acl_add_replace' > > > > > > > > > > function) > > > > > * Set that ACL to the interfaces involved (via the > > > > > 'acl_interface_set_acl_list' > > > > > function) > > > > > > > > > > After performing the above steps the traffic was correctly being > > > > > blocked. > > > > > > > > > > However, when I decided to enable the SSH traffic again, I simply > > > > > deleted the ACL (via the 'acl_del' function) with the consequence > > > > > though that the traffic was still being denied. > > > > > > > > > > Is this behaviour correct? > > > > > If so what would be the right way to unset hence disable a given ACL > > > > > from an interface (or multiple)? > > > > > > > > > > > > > > > Thanks, > > > > > Marco > > > > > > > > > > _______________________________________________ > > > > > vpp-dev mailing list > > > > > vpp-dev@lists.fd.io > > > > > https://lists.fd.io/mailman/listinfo/vpp-dev > > > > _______________________________________________ > > > > vpp-dev mailing list > > > > vpp-dev@lists.fd.io > > > > https://lists.fd.io/mailman/listinfo/vpp-dev > > > > > > > > > _______________________________________________ vpp-dev mailing list vpp-dev@lists.fd.io https://lists.fd.io/mailman/listinfo/vpp-dev
