feat: unified PDP plugin — closes #2223 by yiannis2804 · Pull Request #2640 · IBM/mcp-context-forge

yiannis2804 · 2026-02-01T22:46:28Z

🔗 Related Issue

This feature was developed as part of the SWENG Group 5 project (Trinity College Dublin).

📝 Summary

Adds a unified Policy Decision Point plugin that orchestrates access-control decisions across multiple policy engines (Native RBAC, MAC, OPA, Cedar) through a single gateway hook interface. The plugin hooks into tool_pre_invoke and resource_pre_fetch, evaluates the request against enabled engines, and either passes through or blocks with a PluginViolation.

🏷️ Type of Change

🧪 Verification

Check	Command	Status
Lint suite	`make lint`	✅ 10/10
Unit tests	`make test`	✅ 46 passed
Coverage ≥ 90%	`make coverage`	⬜ 86% (OPA/Cedar require sidecars)

✅ Checklist

Code formatted (make black isort pre-commit)
Tests added/updated for changes
Documentation updated (if applicable)
No secrets or credentials committed

📓 Notes (optional)

Plugin ships as mode: disabled — safe default, no behaviour change until explicitly enabled.
Native RBAC and MAC engines work out of the box (pure Python, no sidecars).
OPA and Cedar engines require their respective sidecars to be running — see plugins/unified_pdp/README.md.
Combination modes supported: all_must_allow | any_allow | first_match.
Admin UI ([FEATURE][POLICY]: Policy testing and simulation sandbox #2226), REST API ([FEATURE][AUTH]: Just-in-time (JIT) access and temporary privilege elevation #2227), audit trail ([FEATURE][POLICY]: Policy audit trail and decision logging #2225), compliance reporting ([FEATURE][COMPLIANCE]: Compliance report generator - FedRAMP/HIPAA/SOC2 automation #2224), and GitOps ([FEATURE][POLICY]: Policy GitOps and version control #2238) are tracked as separate issues.

crivetimihai · 2026-02-01T23:35:34Z

Thanks @yiannis2804 - cool PR. Leave it with me for a bit, I will rebase this to the latest main (as a PR that just bumped unit test coverage from ~63 to 83 was just merged) - and I have a few things I'd like to change as well. Will push the PR back to this branch in a bit, along with the feedback and list of changes.

Cheers!

Adds a single plugin entry point that orchestrates access-control decisions across multiple policy engines (Native RBAC, MAC, OPA, Cedar). - plugins/unified_pdp/unified_pdp.py — Plugin class, hooks into tool_pre_invoke and resource_pre_fetch - plugins/unified_pdp/pdp.py — PolicyDecisionPoint orchestrator - plugins/unified_pdp/pdp_models.py — Pydantic models (Subject, Resource, Context, AccessDecision, config types) - plugins/unified_pdp/adapter.py — Abstract engine adapter base class - plugins/unified_pdp/cache.py — TTL-aware decision cache - plugins/unified_pdp/engines/ — Four engine adapters: native_engine, mac_engine, opa_engine, cedar_engine - plugins/unified_pdp/default_rules.json — Starter RBAC ruleset - tests/unit/plugins/test_unified_pdp.py — 46 unit tests - plugins/config.yaml — Plugin registration (mode: disabled) - MANIFEST.in — Added recursive-include plugins *.json Combination modes: all_must_allow | any_allow | first_match Native RBAC and MAC work out of the box. OPA and Cedar require their respective sidecars (see README). Closes IBM#2223 Signed-off-by: yiannis2804 <yiannis2804@gmail.com>

13 tests covering UnifiedPDPPlugin hook methods (tool_pre_invoke, resource_pre_fetch), subject extraction (dict/string/None user), action string formatting, resource type mapping, and _build_pdp. unified_pdp.py now at 100% coverage. Remaining gaps are in OPA and Cedar engine adapters which require external sidecars to test. Signed-off-by: yiannis2804 <yiannis2804@gmail.com>

Signed-off-by: yiannis2804 <yiannis2804@gmail.com>

- Fix undefined variable eng_type in pdp.py:get_effective_permissions() - Add shutdown() lifecycle method to UnifiedPDPPlugin to properly close HTTP clients for OPA/Cedar engines - Convert tests from respx to pytest-httpx (project standard) - Add test for shutdown() method Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

- Remove unused import List from mac_engine.py - Remove unused variable first_deny from pdp.py Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

…view - Cache key now includes user_agent and context.extra to prevent incorrect cached decisions when policies depend on these fields (MAC operation override, OPA/Cedar context-based rules) - Plugin now extracts IP and user_agent from HTTP headers and passes to PDP context for policy evaluation - Plugin passes tool args to context.extra and resource metadata to resource.annotations for fine-grained policy checks - Exception handling in _evaluate_parallel/_evaluate_sequential now catches all exceptions (not just TimeoutError/PolicyEvaluationError) to prevent crashing the whole request on unexpected errors - Native RBAC docstring corrected: only JSON files are supported (not YAML) Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

Extract classification_level from tool args and resource metadata so MAC engine can make proper Bell-LaPadula decisions instead of always denying due to missing classification. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

crivetimihai · 2026-02-02T00:36:27Z

@yiannis2804 — Thank you for this substantial contribution! The unified PDP architecture is well-designed with good separation of concerns between the plugin layer, orchestrator, engines, and cache.

I've rebased the branch onto the latest main and made the following fixes:

Fixes Applied

1. Bug: Undefined variable `eng_type` in `pdp.py`

The get_effective_permissions() method referenced eng_type but the loop discarded it. Fixed by changing for _, adapter to for eng_type, adapter.

2. Missing `shutdown()` lifecycle method

Added shutdown() to UnifiedPDPPlugin to properly close HTTP clients for OPA/Cedar engines.

3. Wrong test dependency (`respx` vs `pytest-httpx`)

Rewrote tests to use pytest-httpx (the project standard).

4. Linting issues

Removed unused import List from mac_engine.py
Removed unused variable first_deny from pdp.py

5. Cache key security issue

Cache key now includes user_agent and context.extra to prevent incorrect cached decisions when policies depend on these fields.

6. Plugin context enrichment

Extract IP and user_agent from HTTP headers
Pass tool args to context.extra
Pass metadata to resource.annotations

7. Exception handling

Broadened exception handling in _evaluate_parallel/_evaluate_sequential to catch all exceptions and return default_decision instead of crashing.

8. MAC engine classification_level

Extract classification_level from tool args and resource metadata so MAC engine can make proper Bell-LaPadula decisions.

9. Native RBAC docstring

Corrected docstring to say "JSON file" (removed incorrect YAML claim).

10. Full docstring coverage

Ensure full docstring coverage to pass ruff and interrogate checks

Commits Added

f397ff1d fix(unified-pdp): extract classification_level for MAC engine
e254571a fix(unified-pdp): address review findings from additional security review
dc444975 chore(unified-pdp): fix linting issues
e0e42046 fix(unified-pdp): fix bugs and improve tests

All 60 tests pass. Ready for final review!

Add missing docstrings to all public functions and methods in the unified_pdp plugin to satisfy the project's 100% docstring coverage requirement enforced by interrogate. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

Add complete Args, Returns, Raises, and Attributes documentation to all public functions and methods in the unified_pdp plugin, matching the project's docstring style with full parameter descriptions. Files updated: - adapter.py: PolicyEvaluationError, PolicyEngineAdapter methods - cache.py: _build_cache_key, _CacheEntry, DecisionCache methods - pdp.py: PolicyDecisionPoint and all evaluation/combination methods - engines/cedar_engine.py: CedarEngineAdapter and all methods - engines/mac_engine.py: MACEngineAdapter and all methods - engines/native_engine.py: NativeRBACAdapter and all methods - engines/opa_engine.py: OPAEngineAdapter and all methods - unified_pdp.py: shutdown lifecycle method Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

yiannis2804 · 2026-02-02T01:10:12Z

Thanks @crivetimihai — really appreciate the thorough review and improvements. Everything looks great from my side.

Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

crivetimihai · 2026-02-02T01:31:04Z

Great, looks like testing passes - merging!

yiannis2804 · 2026-02-02T01:35:20Z

Thanks @crivetimihai — really appreciate the thorough review and improvements. Glad to see this merged!
This was developed by SWENG Group 5, and it’s great to see it land in main.

* feat: unified PDP plugin for issue IBM#2223 Adds a single plugin entry point that orchestrates access-control decisions across multiple policy engines (Native RBAC, MAC, OPA, Cedar). - plugins/unified_pdp/unified_pdp.py — Plugin class, hooks into tool_pre_invoke and resource_pre_fetch - plugins/unified_pdp/pdp.py — PolicyDecisionPoint orchestrator - plugins/unified_pdp/pdp_models.py — Pydantic models (Subject, Resource, Context, AccessDecision, config types) - plugins/unified_pdp/adapter.py — Abstract engine adapter base class - plugins/unified_pdp/cache.py — TTL-aware decision cache - plugins/unified_pdp/engines/ — Four engine adapters: native_engine, mac_engine, opa_engine, cedar_engine - plugins/unified_pdp/default_rules.json — Starter RBAC ruleset - tests/unit/plugins/test_unified_pdp.py — 46 unit tests - plugins/config.yaml — Plugin registration (mode: disabled) - MANIFEST.in — Added recursive-include plugins *.json Combination modes: all_must_allow | any_allow | first_match Native RBAC and MAC work out of the box. OPA and Cedar require their respective sidecars (see README). Closes IBM#2223 Signed-off-by: yiannis2804 <yiannis2804@gmail.com> * test: add plugin class unit tests, coverage 86% 13 tests covering UnifiedPDPPlugin hook methods (tool_pre_invoke, resource_pre_fetch), subject extraction (dict/string/None user), action string formatting, resource type mapping, and _build_pdp. unified_pdp.py now at 100% coverage. Remaining gaps are in OPA and Cedar engine adapters which require external sidecars to test. Signed-off-by: yiannis2804 <yiannis2804@gmail.com> * docs: add detailed README for unified PDP plugin Signed-off-by: yiannis2804 <yiannis2804@gmail.com> * fix(unified-pdp): fix bugs and improve tests - Fix undefined variable eng_type in pdp.py:get_effective_permissions() - Add shutdown() lifecycle method to UnifiedPDPPlugin to properly close HTTP clients for OPA/Cedar engines - Convert tests from respx to pytest-httpx (project standard) - Add test for shutdown() method Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * chore(unified-pdp): fix linting issues - Remove unused import List from mac_engine.py - Remove unused variable first_deny from pdp.py Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * fix(unified-pdp): address review findings from additional security review - Cache key now includes user_agent and context.extra to prevent incorrect cached decisions when policies depend on these fields (MAC operation override, OPA/Cedar context-based rules) - Plugin now extracts IP and user_agent from HTTP headers and passes to PDP context for policy evaluation - Plugin passes tool args to context.extra and resource metadata to resource.annotations for fine-grained policy checks - Exception handling in _evaluate_parallel/_evaluate_sequential now catches all exceptions (not just TimeoutError/PolicyEvaluationError) to prevent crashing the whole request on unexpected errors - Native RBAC docstring corrected: only JSON files are supported (not YAML) Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * fix(unified-pdp): extract classification_level for MAC engine Extract classification_level from tool args and resource metadata so MAC engine can make proper Bell-LaPadula decisions instead of always denying due to missing classification. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * docs: add docstrings for 100% interrogate coverage Add missing docstrings to all public functions and methods in the unified_pdp plugin to satisfy the project's 100% docstring coverage requirement enforced by interrogate. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * docs: add comprehensive Google-style docstrings to unified_pdp Add complete Args, Returns, Raises, and Attributes documentation to all public functions and methods in the unified_pdp plugin, matching the project's docstring style with full parameter descriptions. Files updated: - adapter.py: PolicyEvaluationError, PolicyEngineAdapter methods - cache.py: _build_cache_key, _CacheEntry, DecisionCache methods - pdp.py: PolicyDecisionPoint and all evaluation/combination methods - engines/cedar_engine.py: CedarEngineAdapter and all methods - engines/mac_engine.py: MACEngineAdapter and all methods - engines/native_engine.py: NativeRBACAdapter and all methods - engines/opa_engine.py: OPAEngineAdapter and all methods - unified_pdp.py: shutdown lifecycle method Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * docs: add __init__ docstring to PolicyEvaluationError Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> --------- Signed-off-by: yiannis2804 <yiannis2804@gmail.com> Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> Co-authored-by: Mihai Criveti <crivetimihai@gmail.com> Signed-off-by: hughhennnelly <hughhennelly06@gmail.com>

* feat: unified PDP plugin for issue IBM#2223 Adds a single plugin entry point that orchestrates access-control decisions across multiple policy engines (Native RBAC, MAC, OPA, Cedar). - plugins/unified_pdp/unified_pdp.py — Plugin class, hooks into tool_pre_invoke and resource_pre_fetch - plugins/unified_pdp/pdp.py — PolicyDecisionPoint orchestrator - plugins/unified_pdp/pdp_models.py — Pydantic models (Subject, Resource, Context, AccessDecision, config types) - plugins/unified_pdp/adapter.py — Abstract engine adapter base class - plugins/unified_pdp/cache.py — TTL-aware decision cache - plugins/unified_pdp/engines/ — Four engine adapters: native_engine, mac_engine, opa_engine, cedar_engine - plugins/unified_pdp/default_rules.json — Starter RBAC ruleset - tests/unit/plugins/test_unified_pdp.py — 46 unit tests - plugins/config.yaml — Plugin registration (mode: disabled) - MANIFEST.in — Added recursive-include plugins *.json Combination modes: all_must_allow | any_allow | first_match Native RBAC and MAC work out of the box. OPA and Cedar require their respective sidecars (see README). Closes IBM#2223 Signed-off-by: yiannis2804 <yiannis2804@gmail.com> * test: add plugin class unit tests, coverage 86% 13 tests covering UnifiedPDPPlugin hook methods (tool_pre_invoke, resource_pre_fetch), subject extraction (dict/string/None user), action string formatting, resource type mapping, and _build_pdp. unified_pdp.py now at 100% coverage. Remaining gaps are in OPA and Cedar engine adapters which require external sidecars to test. Signed-off-by: yiannis2804 <yiannis2804@gmail.com> * docs: add detailed README for unified PDP plugin Signed-off-by: yiannis2804 <yiannis2804@gmail.com> * fix(unified-pdp): fix bugs and improve tests - Fix undefined variable eng_type in pdp.py:get_effective_permissions() - Add shutdown() lifecycle method to UnifiedPDPPlugin to properly close HTTP clients for OPA/Cedar engines - Convert tests from respx to pytest-httpx (project standard) - Add test for shutdown() method Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * chore(unified-pdp): fix linting issues - Remove unused import List from mac_engine.py - Remove unused variable first_deny from pdp.py Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * fix(unified-pdp): address review findings from additional security review - Cache key now includes user_agent and context.extra to prevent incorrect cached decisions when policies depend on these fields (MAC operation override, OPA/Cedar context-based rules) - Plugin now extracts IP and user_agent from HTTP headers and passes to PDP context for policy evaluation - Plugin passes tool args to context.extra and resource metadata to resource.annotations for fine-grained policy checks - Exception handling in _evaluate_parallel/_evaluate_sequential now catches all exceptions (not just TimeoutError/PolicyEvaluationError) to prevent crashing the whole request on unexpected errors - Native RBAC docstring corrected: only JSON files are supported (not YAML) Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * fix(unified-pdp): extract classification_level for MAC engine Extract classification_level from tool args and resource metadata so MAC engine can make proper Bell-LaPadula decisions instead of always denying due to missing classification. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * docs: add docstrings for 100% interrogate coverage Add missing docstrings to all public functions and methods in the unified_pdp plugin to satisfy the project's 100% docstring coverage requirement enforced by interrogate. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * docs: add comprehensive Google-style docstrings to unified_pdp Add complete Args, Returns, Raises, and Attributes documentation to all public functions and methods in the unified_pdp plugin, matching the project's docstring style with full parameter descriptions. Files updated: - adapter.py: PolicyEvaluationError, PolicyEngineAdapter methods - cache.py: _build_cache_key, _CacheEntry, DecisionCache methods - pdp.py: PolicyDecisionPoint and all evaluation/combination methods - engines/cedar_engine.py: CedarEngineAdapter and all methods - engines/mac_engine.py: MACEngineAdapter and all methods - engines/native_engine.py: NativeRBACAdapter and all methods - engines/opa_engine.py: OPAEngineAdapter and all methods - unified_pdp.py: shutdown lifecycle method Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> * docs: add __init__ docstring to PolicyEvaluationError Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> --------- Signed-off-by: yiannis2804 <yiannis2804@gmail.com> Signed-off-by: Mihai Criveti <crivetimihai@gmail.com> Co-authored-by: Mihai Criveti <crivetimihai@gmail.com>

yiannis2804 requested review from crivetimihai, kevalmahajan and madhav165 as code owners February 1, 2026 22:46

yiannis2804 force-pushed the feature/issue-2223-unified-pdp branch 4 times, most recently from 48bbb28 to 82e85e8 Compare February 1, 2026 23:08

crivetimihai self-assigned this Feb 1, 2026

crivetimihai added the plugins label Feb 1, 2026

crivetimihai requested review from araujof and terylt February 1, 2026 23:35

crivetimihai added this to the Release 1.0.0-RC1 milestone Feb 1, 2026

crivetimihai added the tcd SwEng Projects label Feb 1, 2026

yiannis2804 and others added 7 commits February 2, 2026 00:15

docs: add detailed README for unified PDP plugin

c075964

Signed-off-by: yiannis2804 <yiannis2804@gmail.com>

chore(unified-pdp): fix linting issues

dc44497

- Remove unused import List from mac_engine.py - Remove unused variable first_deny from pdp.py Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

crivetimihai force-pushed the feature/issue-2223-unified-pdp branch from 82e85e8 to f397ff1 Compare February 2, 2026 00:35

crivetimihai added 2 commits February 2, 2026 00:49

docs: add docstrings for 100% interrogate coverage

9719d6d

Add missing docstrings to all public functions and methods in the unified_pdp plugin to satisfy the project's 100% docstring coverage requirement enforced by interrogate. Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

crivetimihai approved these changes Feb 2, 2026

View reviewed changes

docs: add __init__ docstring to PolicyEvaluationError

3c0dbfb

Signed-off-by: Mihai Criveti <crivetimihai@gmail.com>

crivetimihai merged commit 6d65f45 into IBM:main Feb 2, 2026
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feat: unified PDP plugin — closes #2223#2640

feat: unified PDP plugin — closes #2223#2640
crivetimihai merged 10 commits intoIBM:mainfrom
yiannis2804:feature/issue-2223-unified-pdp

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🔗 Related Issue

This feature was developed as part of the SWENG Group 5 project (Trinity College Dublin).

📝 Summary

🏷️ Type of Change

🧪 Verification

✅ Checklist

📓 Notes (optional)

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crivetimihai commented Feb 1, 2026

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Fixes Applied

1. Bug: Undefined variable eng_type in pdp.py

2. Missing shutdown() lifecycle method

3. Wrong test dependency (respx vs pytest-httpx)

4. Linting issues

5. Cache key security issue

6. Plugin context enrichment

7. Exception handling

8. MAC engine classification_level

9. Native RBAC docstring

10. Full docstring coverage

Commits Added

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yiannis2804 commented Feb 1, 2026 •

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crivetimihai commented Feb 2, 2026 •

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1. Bug: Undefined variable `eng_type` in `pdp.py`

2. Missing `shutdown()` lifecycle method

3. Wrong test dependency (`respx` vs `pytest-httpx`)