# CONTRACT-FINDINGS-LEDGER-RLS-011: Row-Level Security & Partitioning

> **Status:** Published
> **Version:** 1.0.0
> **Published:** 2025-12-05
> **Owners:** Platform/DB Guild, Findings Ledger Guild
> **Unblocks:** LEDGER-TEN-48-001-DEV, DEVOPS-LEDGER-TEN-48-001-REL

## Overview

This contract specifies the Row-Level Security (RLS) and partitioning strategy for the Findings Ledger module. It is based on the proven Evidence Locker implementation pattern and adapted for Findings Ledger's schema.

## Current State (Already Implemented)

The Findings Ledger already has these foundational elements:

### 1. LIST Partitioning by Tenant

All tables are partitioned by `tenant_id`:

```sql
-- Example from ledger_events
CREATE TABLE ledger_events (
    tenant_id TEXT NOT NULL,
    ...
) PARTITION BY LIST (tenant_id);
```

**Tables with partitioning:**
- `ledger_events`
- `ledger_merkle_roots`
- `findings_projection`
- `finding_history`
- `triage_actions`
- `ledger_attestations`
- `orchestrator_exports`
- `airgap_imports`

### 2. Session Variable Configuration

Connection setup in `LedgerDataSource.cs`:

```csharp
await using var cmd = connection.CreateCommand();
cmd.CommandText = "SELECT set_config('app.current_tenant', @tenant, false);";
cmd.Parameters.AddWithValue("tenant", tenantId);
await cmd.ExecuteNonQueryAsync(ct);
```

### 3. HTTP Header Tenant Extraction

From `Program.cs`:
- Header: `X-Stella-Tenant`
- Validation: Non-empty required
- Error: 400 Bad Request if missing

### 4. Application-Level Query Filtering

All repository queries include `WHERE tenant_id = @tenant` (defense in depth).

---

## Required Implementation (The Missing 10%)

### 1. Tenant Validation Function

Create a schema function following the Evidence Locker pattern:

```sql
-- Schema for application-level functions
CREATE SCHEMA IF NOT EXISTS findings_ledger_app;

-- Tenant validation function (TEXT version for Ledger compatibility)
CREATE OR REPLACE FUNCTION findings_ledger_app.require_current_tenant()
RETURNS TEXT
LANGUAGE plpgsql
STABLE
AS $$
DECLARE
    tenant_text TEXT;
BEGIN
    tenant_text := current_setting('app.current_tenant', true);
    IF tenant_text IS NULL OR length(trim(tenant_text)) = 0 THEN
        RAISE EXCEPTION 'app.current_tenant is not set for the current session'
            USING ERRCODE = 'P0001';
    END IF;
    RETURN tenant_text;
END;
$$;

COMMENT ON FUNCTION findings_ledger_app.require_current_tenant() IS
    'Returns the current tenant ID from session variable, raises exception if not set';
```

### 2. RLS Policies for All Tables

Apply to each tenant-scoped table:

```sql
-- ============================================
-- ledger_events
-- ============================================
ALTER TABLE ledger_events ENABLE ROW LEVEL SECURITY;
ALTER TABLE ledger_events FORCE ROW LEVEL SECURITY;

CREATE POLICY ledger_events_tenant_isolation
    ON ledger_events
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- ledger_merkle_roots
-- ============================================
ALTER TABLE ledger_merkle_roots ENABLE ROW LEVEL SECURITY;
ALTER TABLE ledger_merkle_roots FORCE ROW LEVEL SECURITY;

CREATE POLICY ledger_merkle_roots_tenant_isolation
    ON ledger_merkle_roots
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- findings_projection
-- ============================================
ALTER TABLE findings_projection ENABLE ROW LEVEL SECURITY;
ALTER TABLE findings_projection FORCE ROW LEVEL SECURITY;

CREATE POLICY findings_projection_tenant_isolation
    ON findings_projection
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- finding_history
-- ============================================
ALTER TABLE finding_history ENABLE ROW LEVEL SECURITY;
ALTER TABLE finding_history FORCE ROW LEVEL SECURITY;

CREATE POLICY finding_history_tenant_isolation
    ON finding_history
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- triage_actions
-- ============================================
ALTER TABLE triage_actions ENABLE ROW LEVEL SECURITY;
ALTER TABLE triage_actions FORCE ROW LEVEL SECURITY;

CREATE POLICY triage_actions_tenant_isolation
    ON triage_actions
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- ledger_attestations
-- ============================================
ALTER TABLE ledger_attestations ENABLE ROW LEVEL SECURITY;
ALTER TABLE ledger_attestations FORCE ROW LEVEL SECURITY;

CREATE POLICY ledger_attestations_tenant_isolation
    ON ledger_attestations
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- orchestrator_exports
-- ============================================
ALTER TABLE orchestrator_exports ENABLE ROW LEVEL SECURITY;
ALTER TABLE orchestrator_exports FORCE ROW LEVEL SECURITY;

CREATE POLICY orchestrator_exports_tenant_isolation
    ON orchestrator_exports
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());

-- ============================================
-- airgap_imports
-- ============================================
ALTER TABLE airgap_imports ENABLE ROW LEVEL SECURITY;
ALTER TABLE airgap_imports FORCE ROW LEVEL SECURITY;

CREATE POLICY airgap_imports_tenant_isolation
    ON airgap_imports
    FOR ALL
    USING (tenant_id = findings_ledger_app.require_current_tenant())
    WITH CHECK (tenant_id = findings_ledger_app.require_current_tenant());
```

### 3. System/Admin Bypass Role

For migrations and cross-tenant admin operations:

```sql
-- Create admin role that bypasses RLS
CREATE ROLE findings_ledger_admin NOLOGIN;

-- Grant bypass to admin role
ALTER ROLE findings_ledger_admin BYPASSRLS;

-- Application service account for migrations
GRANT findings_ledger_admin TO stellaops_migration_user;
```

---

## Connection Patterns

### Regular Connections (Tenant-Scoped)

```csharp
public async Task<NpgsqlConnection> OpenTenantConnectionAsync(
    string tenantId,
    CancellationToken ct)
{
    var connection = await _dataSource.OpenConnectionAsync(ct);

    await using var cmd = connection.CreateCommand();
    cmd.CommandText = "SELECT set_config('app.current_tenant', @tenant, false)";
    cmd.Parameters.AddWithValue("tenant", tenantId);
    await cmd.ExecuteNonQueryAsync(ct);

    return connection;
}
```

### System Connections (No Tenant - Migrations Only)

```csharp
public async Task<NpgsqlConnection> OpenSystemConnectionAsync(CancellationToken ct)
{
    // Uses admin role, no tenant set
    // ONLY for: migrations, health checks, cross-tenant admin ops
    var connection = await _adminDataSource.OpenConnectionAsync(ct);
    return connection;
}
```

---

## Compliance Validation

### Pre-Deployment Checks

```sql
-- 1. Verify RLS enabled on all tables
SELECT schemaname, tablename, rowsecurity
FROM pg_tables
WHERE schemaname = 'public'
  AND tablename IN (
    'ledger_events', 'ledger_merkle_roots', 'findings_projection',
    'finding_history', 'triage_actions', 'ledger_attestations',
    'orchestrator_exports', 'airgap_imports'
  )
  AND rowsecurity = false;
-- Expected: 0 rows (all should have RLS enabled)

-- 2. Verify policies exist for all tables
SELECT tablename, policyname
FROM pg_policies
WHERE schemaname = 'public'
  AND tablename IN (
    'ledger_events', 'ledger_merkle_roots', 'findings_projection',
    'finding_history', 'triage_actions', 'ledger_attestations',
    'orchestrator_exports', 'airgap_imports'
  );
-- Expected: 8 rows (one policy per table)

-- 3. Verify tenant validation function exists
SELECT proname, prosrc
FROM pg_proc
WHERE proname = 'require_current_tenant'
  AND pronamespace = (SELECT oid FROM pg_namespace WHERE nspname = 'findings_ledger_app');
-- Expected: 1 row
```

### Runtime Regression Tests

```csharp
[Fact]
public async Task CrossTenantRead_ShouldFail_WithRlsError()
{
    // Arrange: Insert data as tenant A
    await using var connA = await OpenTenantConnectionAsync("tenant-a", ct);
    await InsertFinding(connA, "finding-1", ct);

    // Act: Try to read as tenant B
    await using var connB = await OpenTenantConnectionAsync("tenant-b", ct);
    var result = await QueryFindings(connB, ct);

    // Assert: No rows returned (RLS blocks cross-tenant access)
    Assert.Empty(result);
}

[Fact]
public async Task NoTenantContext_ShouldFail_WithException()
{
    // Arrange: Open connection without setting tenant
    await using var conn = await _dataSource.OpenConnectionAsync(ct);

    // Act & Assert: Query should fail
    await Assert.ThrowsAsync<PostgresException>(async () =>
    {
        await conn.ExecuteAsync("SELECT * FROM ledger_events LIMIT 1");
    });
}
```

---

## Migration Strategy

### Migration File: `007_enable_rls.sql`

```sql
-- Migration: Enable Row-Level Security for Findings Ledger
-- Date: 2025-12-XX
-- Task: LEDGER-TEN-48-001-DEV

BEGIN;

-- 1. Create app schema and tenant function
CREATE SCHEMA IF NOT EXISTS findings_ledger_app;

CREATE OR REPLACE FUNCTION findings_ledger_app.require_current_tenant()
RETURNS TEXT LANGUAGE plpgsql STABLE AS $$
DECLARE tenant_text TEXT;
BEGIN
    tenant_text := current_setting('app.current_tenant', true);
    IF tenant_text IS NULL OR length(trim(tenant_text)) = 0 THEN
        RAISE EXCEPTION 'app.current_tenant is not set' USING ERRCODE = 'P0001';
    END IF;
    RETURN tenant_text;
END;
$$;

-- 2. Enable RLS on all tables (see full SQL above)
-- ... (apply to all 8 tables)

-- 3. Create admin bypass role
CREATE ROLE IF NOT EXISTS findings_ledger_admin NOLOGIN BYPASSRLS;

COMMIT;
```

### Rollback: `007_enable_rls_rollback.sql`

```sql
BEGIN;

-- Disable RLS on all tables
ALTER TABLE ledger_events DISABLE ROW LEVEL SECURITY;
ALTER TABLE ledger_merkle_roots DISABLE ROW LEVEL SECURITY;
ALTER TABLE findings_projection DISABLE ROW LEVEL SECURITY;
ALTER TABLE finding_history DISABLE ROW LEVEL SECURITY;
ALTER TABLE triage_actions DISABLE ROW LEVEL SECURITY;
ALTER TABLE ledger_attestations DISABLE ROW LEVEL SECURITY;
ALTER TABLE orchestrator_exports DISABLE ROW LEVEL SECURITY;
ALTER TABLE airgap_imports DISABLE ROW LEVEL SECURITY;

-- Drop policies
DROP POLICY IF EXISTS ledger_events_tenant_isolation ON ledger_events;
DROP POLICY IF EXISTS ledger_merkle_roots_tenant_isolation ON ledger_merkle_roots;
DROP POLICY IF EXISTS findings_projection_tenant_isolation ON findings_projection;
DROP POLICY IF EXISTS finding_history_tenant_isolation ON finding_history;
DROP POLICY IF EXISTS triage_actions_tenant_isolation ON triage_actions;
DROP POLICY IF EXISTS ledger_attestations_tenant_isolation ON ledger_attestations;
DROP POLICY IF EXISTS orchestrator_exports_tenant_isolation ON orchestrator_exports;
DROP POLICY IF EXISTS airgap_imports_tenant_isolation ON airgap_imports;

-- Drop function and schema
DROP FUNCTION IF EXISTS findings_ledger_app.require_current_tenant();
DROP SCHEMA IF EXISTS findings_ledger_app;

COMMIT;
```

---

## Audit Requirements

1. **All write operations** must log `tenant_id` and `actor_id`
2. **System connections** must log reason and operator
3. **RLS bypass operations** must be audited separately
4. **Cross-tenant queries** (admin only) must require justification ticket

---

## Reference Implementation

Evidence Locker RLS implementation:
- `src/EvidenceLocker/StellaOps.EvidenceLocker/StellaOps.EvidenceLocker.Infrastructure/Db/Migrations/001_initial_schema.sql`

---

## Approval Checklist

- [ ] Platform/DB Guild: Schema and RLS patterns approved
- [ ] Security Guild: Tenant isolation verified
- [ ] Findings Ledger Guild: Implementation feasible
- [ ] DevOps Guild: Migration/rollback strategy approved

---

## Changelog

| Version | Date | Author | Changes |
|---------|------|--------|---------|
| 1.0.0 | 2025-12-05 | Platform Guild | Initial contract based on Evidence Locker pattern |