Supporting allowNoIndices means that the security plugin has a behaviour much more similar to vanilla es when dealing with wildcard expressions that match no indices, or empty clusters. The default for most request is to allow no indices, but security plugin could only disallow no indices all the time up until now.
The technical problem was that when anything gets resolved to an empty set of indices, we couldn't let that go through to es core, as that would become resolved to all indices by es core, which would be a security hole. We have now found a way though to replace an empty set of indices with something that es core will for sure resolve to no indices, so we can let the request through. We simply replace empty indices with '-*'.
Multi apis requests (e.g. _msearch) have yet to be fixed, as all their indices end up in the same bucket while they should each be authorized separately, so that every specific item can fail or be let through.
Original commit: elastic/x-pack-elasticsearch@0f67a0bfea
For all the requests that support multiple indices and wildcards, hence implementing IndicesRequest.Replaceable, we replace the wildcard expressions with the explicit names of the authorized indices they match. _all or empty indices is treated as a wildcard expression. We can also honour the ignore_unavailable option by going over all the explicit names and filter out the non authorized ones when ignore_unavailable is set to true. If ignore_unavailable is set to false, we leave everything as-is, which will cause an authorization exception to be thrown if only one of those explicit indices is not authorized for the current user.
This is the first step towards resolving elastic/elasticsearch#1250. The remaining issue is that in case we are left with no indices after stripping out the ones that the user is not authorized for, we throw an authorization exception rather than returning an empty response. That will require honouring the allow_no_indices option, which will also change the behaviour when a cluster is empty.
Relates to elastic/elasticsearch#1250
Original commit: elastic/x-pack-elasticsearch@e4ca940d05
Nik Everett
Ryan Ernst
javanna