Replaces #18812
Upgraded with:
```
find . -name '*.go' -exec sed -i s/"github.com\/hashicorp\/go-msgpack\/codec"/"github.com\/hashicorp\/go-msgpack\/v2\/codec/" '{}' ';'
find . -name '*.go' -exec sed -i s/"github.com\/hashicorp\/net-rpc-msgpackrpc"/"github.com\/hashicorp\/net-rpc-msgpackrpc\/v2/" '{}' ';'
go get
go get -v -u github.com/hashicorp/raft-boltdb/v2
go get -v github.com/hashicorp/serf@5d32001edfaa18d1c010af65db707cdb38141e80
```
see https://github.com/hashicorp/go-msgpack/releases/tag/v2.1.0
for details
The RPC handlers expect to see `nil` ACL objects whenever ACLs are disabled. By
using `nil` as a sentinel value, we have the risk of nil pointer exceptions and
improper handling of `nil` when returned from our various auth methods that can
lead to privilege escalation bugs. This is the final patch in a series to
eliminate the use of `nil` ACLs as a sentinel value for when ACLs are disabled.
This patch adds a new virtual ACL policy field for when ACLs are disabled and
updates our authentication logic to use it. Included:
* Extends auth package tests to demonstrate that nil ACLs are treated as failed
auth and disabled ACLs succeed auth.
* Adds a new `AllowDebug` ACL check for the weird special casing we have for
pprof debugging when ACLs are disabled.
* Removes the remaining unexported methods (and repeated tests) from the
`nomad/acl.go` file.
* Update the semgrep rules to detect improper nil ACL checking and remove the
old invalid ACL checks.
* Update the contributing guide for RPC authentication.
Ref: https://github.com/hashicorp/nomad-enterprise/pull/1218
Ref: https://github.com/hashicorp/nomad/pull/18703
Ref: https://github.com/hashicorp/nomad/pull/18715
Ref: https://github.com/hashicorp/nomad/pull/16799
Ref: https://github.com/hashicorp/nomad/pull/18730
Ref: https://github.com/hashicorp/nomad/pull/18744
* Upgrade from hashicorp/go-msgpack v1.1.5 to v2.1.0
Fixes#16808
* Update hashicorp/net-rpc-msgpackrpc to v2 to match go-msgpack
* deps: use go-msgpack v2.0.0
go-msgpack v2.1.0 includes some code changes that we will need to
investigate furthere to assess its impact on Nomad, so keeping this
dependency on v2.0.0 for now since it's no-op.
---------
Co-authored-by: Luiz Aoqui <luiz@hashicorp.com>
Before this change, Client had 2 copies of the config object: config and configCopy. There was no guidance around which to use where (other than configCopy's comment to pass it to alloc runners), both are shared among goroutines and mutated in data racy ways. At least at one point I think the idea was to have `config` be mutable and then grab a lock to overwrite `configCopy`'s pointer atomically. This would have allowed alloc runners to read their config copies in data race safe ways, but this isn't how the current implementation worked.
This change takes the following approach to safely handling configs in the client:
1. `Client.config` is the only copy of the config and all access must go through the `Client.configLock` mutex
2. Since the mutex *only protects the config pointer itself and not fields inside the Config struct:* all config mutation must be done on a *copy* of the config, and then Client's config pointer is overwritten while the mutex is acquired. Alloc runners and other goroutines with the old config pointer will not see config updates.
3. Deep copying is implemented on the Config struct to satisfy the previous approach. The TLS Keyloader is an exception because it has its own internal locking to support mutating in place. An unfortunate complication but one I couldn't find a way to untangle in a timely fashion.
4. To facilitate deep copying I made an *internally backward incompatible API change:* our `helper/funcs` used to turn containers (slices and maps) with 0 elements into nils. This probably saves a few memory allocations but makes it very easy to cause panics. Since my new config handling approach uses more copying, it became very difficult to ensure all code that used containers on configs could handle nils properly. Since this code has caused panics in the past, I fixed it: nil containers are copied as nil, but 0-element containers properly return a new 0-element container. No more "downgrading to nil!"
* command/agent/host: collect host data, multi platform
* nomad/structs/structs: new HostDataRequest/Response
* client/agent_endpoint: add RPC endpoint
* command/agent/agent_endpoint: add Host
* api/agent: add the Host endpoint
* nomad/client_agent_endpoint: add Agent Host with forwarding
* nomad/client_agent_endpoint: use findClientConn
This changes forwardMonitorClient and forwardProfileClient to use
findClientConn, which was cribbed from the common parts of those
funcs.
* command/debug: call agent hosts
* command/agent/host: eliminate calling external programs
Passes in agent enable_debug config to nomad server and client configs.
This allows for rpc endpoints to have more granular control if they
should be enabled or not in combination with ACLs.
enable debug on client test
