This PR is almost a complete rewrite of the ACL system within Consul. It brings the features more in line with other HashiCorp products. Obviously there is quite a bit left to do here but most of it is related docs, testing and finishing the last few commands in the CLI. I will update the PR description and check off the todos as I finish them over the next few days/week.
Description
At a high level this PR is mainly to split ACL tokens from Policies and to split the concepts of Authorization from Identities. A lot of this PR is mostly just to support CRUD operations on ACLTokens and ACLPolicies. These in and of themselves are not particularly interesting. The bigger conceptual changes are in how tokens get resolved, how backwards compatibility is handled and the separation of policy from identity which could lead the way to allowing for alternative identity providers.
On the surface and with a new cluster the ACL system will look very similar to that of Nomads. Both have tokens and policies. Both have local tokens. The ACL management APIs for both are very similar. I even ripped off Nomad's ACL bootstrap resetting procedure. There are a few key differences though.
Nomad requires token and policy replication where Consul only requires policy replication with token replication being opt-in. In Consul local tokens only work with token replication being enabled though.
All policies in Nomad are globally applicable. In Consul all policies are stored and replicated globally but can be scoped to a subset of the datacenters. This allows for more granular access management.
Unlike Nomad, Consul has legacy baggage in the form of the original ACL system. The ramifications of this are:
A server running the new system must still support other clients using the legacy system.
A client running the new system must be able to use the legacy RPCs when the servers in its datacenter are running the legacy system.
The primary ACL DC's servers running in legacy mode needs to be a gate that keeps everything else in the entire multi-DC cluster running in legacy mode.
So not only does this PR implement the new ACL system but has a legacy mode built in for when the cluster isn't ready for new ACLs. Also detecting that new ACLs can be used is automatic and requires no configuration on the part of administrators. This process is detailed more in the "Transitioning from Legacy to New ACL Mode" section below.
This is now using table driven testing. In addition to conversion of old tests I also implemented several new tests for the acl fixes in my previous commit.
In particular the issues I saw with ACLs for prepared queries, keyring and operator all have tests for those and comments indicating that they would have previously failed.
This creates one function that takes a rule and the required permissions and returns whether it should be allowed and whether to leave the decision to the parent acl.
Then this function is used everywhere. This makes acl enforcement consistent.
There were several places where a default allow policy with explicit deny rules wasnt being handled and several others where it wasn’t using the parent acl appropriately but would lump no policy in with a deny policy. All of that has been fixed.
The error handling of the ACL code relies on the presence of certain
magic error messages. Since the error values are sent via RPC between
older and newer consul agents we cannot just replace the magic values
with typed errors and switch to type checks since this would break
compatibility with older clients.
Therefore, this patch moves all magic ACL error messages into the acl
package and provides default error values and helper functions which
determine the type of error.
* Updates Raft library to get new snapshot/restore API.
* Basic backup and restore working, but need some cleanup.
* Breaks out a snapshot module and adds a SHA256 integrity check.
* Adds snapshot ACL and fills in some missing comments.
* Require a consistent read for snapshots.
* Make sure snapshot works if ACLs aren't enabled.
* Adds a bit of package documentation.
* Returns an empty response from restore to avoid EOF errors.
* Adds API client support for snapshots.
* Makes internal file names match on-disk file snapshots.
* Adds DC and token coverage for snapshot API test.
* Adds missing documentation.
* Adds a unit test for the snapshot client endpoint.
* Moves the connection pool out of the client for easier testing.
* Fixes an incidental issue in the prepared query unit test.
I realized I had two servers in bootstrap mode so this wasn't a good setup.
* Adds a half close to the TCP stream and fixes panic on error.
* Adds client and endpoint tests for snapshots.
* Moves the pool back into the snapshot RPC client.
* Adds a TLS test and fixes half-closes for TLS connections.
* Tweaks some comments.
* Adds a low-level snapshot test.
This is independent of Consul so we can pull this out into a library
later if we want to.
* Cleans up snapshot and archive and completes archive tests.
* Sends a clear error for snapshot operations in dev mode.
Snapshots require the Raft snapshots to be readable, which isn't supported
in dev mode. Send a clear error instead of a deep-down Raft one.
* Adds docs for the snapshot endpoint.
* Adds a stale mode and index feedback for snapshot saves.
This gives folks a way to extract data even if the cluster has no
leader.
* Changes the internal format of a snapshot from zip to tgz.
* Pulls in Raft fix to cancel inflight before a restore.
* Pulls in new Raft restore interface.
* Adds metadata to snapshot saves and a verify function.
* Adds basic save and restore snapshot CLI commands.
* Gets rid of tarball extensions and adds restore message.
* Fixes an incidental bad link in the KV docs.
* Adds documentation for the snapshot CLI commands.
* Scuttle any request body when a snapshot is saved.
* Fixes archive unit test error message check.
* Allows for nil output writers in snapshot RPC handlers.
* Renames hash list Decode to DecodeAndVerify.
* Closes the client connection for snapshot ops.
* Lowers timeout for restore ops.
* Updates Raft vendor to get new Restore signature and integrates with Consul.
* Bounces the leader's internal state when we do a restore.
Prior to this change, prepared queries had the following behavior for
ACLs, which will need to change to support templates:
1. A management token, or a token with read access to the service being
queried needed to be provided in order to create a prepared query.
2. The token used to create the prepared query was stored with the query
in the state store and used to execute the query.
3. A management token, or the token used to create the query needed to be
supplied to perform and CRUD operations on an existing prepared query.
This was pretty subtle and complicated behavior, and won't work for
templates since the service name is computed at execution time. To solve
this, we introduce a new "prepared-query" ACL type, where the prefix
applies to the query name for static prepared query types and to the
prefix for template prepared query types.
With this change, the new behavior is:
1. A management token, or a token with "prepared-query" write access to
the query name or (soon) the given template prefix is required to do
any CRUD operations on a prepared query, or to list prepared queries
(the list is filtered by this ACL).
2. You will no longer need a management token to list prepared queries,
but you will only be able to see prepared queries that you have access
to (you get an empty list instead of permission denied).
3. When listing or getting a query, because it was easy to capture
management tokens given the past behavior, this will always blank out
the "Token" field (replacing the contents as <hidden>) for all tokens
unless a management token is supplied. Going forward, we should
discourage people from binding tokens for execution unless strictly
necessary.
4. No token will be captured by default when a prepared query is created.
If the user wishes to supply an execution token then can pass it in via
the "Token" field in the prepared query definition. Otherwise, this
field will default to empty.
5. At execution time, we will use the captured token if it exists with the
prepared query definition, otherwise we will use the token that's passed
in with the request, just like we do for other RPCs (or you can use the
agent's configured token for DNS).
6. Prepared queries with no name (accessible only by ID) will not require
ACLs to create or modify (execution time will depend on the service ACL
configuration). Our argument here is that these are designed to be
ephemeral and the IDs are as good as an ACL. Management tokens will be
able to list all of these.
These changes enable templates, but also enable delegation of authority to
manage the prepared query namespace.
Matt Keeler