[VAULT-35716] Handle lists of values in policy parameters

[blueberry-pi]

Description

As reported in VAULT-35716, policies created with allowed_parameters or denied_parameters do not work as expected if the request assigns a list of values to the allowed/denied parameter instead of a single value.

eg. with a policy:

path "identity/group" {
  capabilities = ["create", "update", "list", "read"]
  denied_parameters = {
    "name" = ["admin_group_*", "ADMIN_GROUP_*", "admin_automation", "ADMIN_AUTOMATION"]
    "policies" = ["*admin-automation-policy*", "*admin-policy*"]    
    
  }
}

a request with parameters {"name":"test_policy_list","policies": ["admin-policy", "admin-automation-policy"], "type": "external"}' should be denied but is allowed because we do not expect policies could be a list of values and attempt to compare the entirety of it as a single value against *admin-automation-policy* and then against *admin-policy*.

AFAICT nothing in our documentation prohibits using a list of values, but we do not handle the case. This PR checks if the input is a slice type, and if so, iterates through it so each value in the slice is being checked against the allow/deny list.

TODO only if you're a HashiCorp employee

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• ENT Breakage: If this PR either 1) removes a public function OR 2) changes the signature
  of a public function, even if that change is in a CE file, double check that
  applying the patch for this PR to the ENT repo and running tests doesn't
  break any tests. Sometimes ENT only tests rely on public functions in CE
  files.
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[github-actions]

CI Results:
All Go tests succeeded! ✅

[github-actions]

Build Results:
All builds succeeded! ✅

[blueberry-pi]

I'm treating this as a bug though it's unclear if we intended for this to work. Let me know if it fits better as an improvement

[blueberry-pi]

Updated to change since it is a difference in behavior that could cause previously passing requests to now fail

[Copilot]

Pull Request Overview

This PR fixes the issue where policy parameter checks fail when a parameter value is provided as a list. Key changes include updating the test cases to use a map-based structure for parameters and refactoring the parameter matching logic to correctly handle slice types for both allowed and denied policy assertions.

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 2 comments.

File	Description
vault/acl_test.go	Updated test cases to support map-based parameters and additional slice test scenarios.
vault/acl.go	Refactored parameter matching functions to distinguish between allowed and denied lists and handle slice types appropriately.

Files not reviewed (1)

• changelog/30551.txt: Language not supported

[Copilot]

[nitpick] The recursive use of valueInParameterList inside valueInAllowedParameterList may cause confusion. Consider renaming or refactoring the helper functions to clearly separate slice handling from single value comparisons.

[Copilot]

[nitpick] The similar recursion pattern in valueInDeniedParameterList using valueInParameterList could be refactored for improved clarity. Clarifying the distinct handling for slices versus single values would enhance maintainability.

[blueberry-pi]

Closing for now as making changes to how policies behave will require more in-depth discussions with engineering and product