server: use a whitelist for non-admin APIs

[knz]

This issue is to address the cleanup and strengthening of the solutions implemented for #42567

• the server code that accepts incoming RPCs and HTTP requests should consider that the request requires admin privileges by default, and only allow non-admins to use the endpoint if the endpoint is in a whitelist. This will prevent mistakenly introducing new privileged APIs without the appropriate privilege checks in the future. Action plan:

  • [ ] share the code that requires admin privileges to the top level incoming request code
  • [ ] introduce a whitelist

• the auth info should be determined very early (during the TLS handshake) and populated in the context for use everywhere, see these two comments:

https://github.com/cockroachdb/cockroach/issues/42567#issuecomment-555568850

and

https://github.com/cockroachdb/cockroach/issues/42567#issuecomment-555641888

Epic: CRDB-1473

Jira issue: CRDB-5247

[knz]

@dhartunian this is one of the issues we discussed earlier today, if you want to keep an eye on it or add it to some to-do list.

[github-actions[bot]]

We have marked this issue as stale because it has been inactive for 18 months. If this issue is still relevant, removing the stale label or adding a comment will keep it active. Otherwise, we'll close it in 10 days to keep the issue queue tidy. Thank you for your contribution to CockroachDB!