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Database Security Audit Report

Repository: /mnt/ollama/git/agent-guardrails-template Focus: mcp-server/internal/database/ Audit Date: 2026-02-08 Auditor: Database Administrator Agent

Executive Summary

The database implementation shows good security practices with parameterized queries, transaction safety, and input validation. However, several medium and low severity issues were identified that should be addressed to improve security posture.

Overall Security Rating: B+ (Good with minor improvements needed)

Findings Summary

Severity	Count	Categories
Critical	0	-
High	0	-
Medium	3	Connection Security, Query Timeouts, Schema Permissions
Low	4	Audit Logging, Input Validation, Error Handling, TLS Defaults
Info	2	Documentation, Best Practices

Detailed Findings

1. Connection Security - Missing TLS Certificate Verification (Medium)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/config/config.go Line: 337-341 Severity: Medium

Issue: The database connection string construction does not explicitly configure SSL root certificate verification when using verify-ca or verify-full modes.

Current Code:

func (c *Config) DatabaseURL() string {
    return fmt.Sprintf("postgresql://%s:%s@%s:%d/%s?sslmode=%s&connect_timeout=%d",
        c.DBUser, c.DBPassword, c.DBHost, c.DBPort, c.DBName, c.DBSSLMode,
        int(c.DBConnectTimeout.Seconds()))
}

Risk: When using verify-ca or verify-full SSL modes, the connection will fail without proper root certificate configuration. The current implementation may silently downgrade to require mode in some driver configurations.

Fix:

func (c *Config) DatabaseURL() string {
    connStr := fmt.Sprintf("postgresql://%s:%s@%s:%d/%s?sslmode=%s&connect_timeout=%d",
        c.DBUser, c.DBPassword, c.DBHost, c.DBPort, c.DBName, c.DBSSLMode,
        int(c.DBConnectTimeout.Seconds()))

    // Add SSL root certificate for verify modes
    if c.DBSSLMode == "verify-ca" || c.DBSSLMode == "verify-full" {
        if c.DBSSLRootCert != "" {
            connStr += fmt.Sprintf("&sslrootcert=%s", c.DBSSLRootCert)
        }
        if c.DBSSLCert != "" && c.DBSSLKey != "" {
            connStr += fmt.Sprintf("&sslcert=%s&sslkey=%s", c.DBSSLCert, c.DBSSLKey)
        }
    }

    return connStr
}

2. Query Timeout Handling - Missing Statement Timeouts (Medium)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/postgres.go Line: 32-63 Severity: Medium

Issue: The database connection pool configuration does not set PostgreSQL statement timeouts, which could allow long-running queries to consume resources indefinitely.

Current Code:

func New(cfg *config.Config) (*DB, error) {
    db, err := sql.Open("pgx", cfg.DatabaseURL())
    // ... pool configuration without statement timeout
}

Risk: A malicious or buggy query could run indefinitely, causing denial of service through connection pool exhaustion.

Fix:

func New(cfg *config.Config) (*DB, error) {
    // Add statement_timeout to connection string or execute after connect
    db, err := sql.Open("pgx", cfg.DatabaseURL())
    if err != nil {
        return nil, fmt.Errorf("failed to open database: %w", err)
    }

    // Set statement timeout to prevent runaway queries
    _, err = db.Exec("SET statement_timeout = '30000'") // 30 seconds
    if err != nil {
        db.Close()
        return nil, fmt.Errorf("failed to set statement timeout: %w", err)
    }

    // ... rest of configuration
}

3. Schema Permissions - Missing Principle of Least Privilege (Medium)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/001_create_tables.up.sql Line: 1-85 Severity: Medium

Issue: Migration files do not define specific database roles or permissions. The application likely runs with a database user that has excessive privileges (possibly superuser).

Current State: No GRANT/REVOKE statements in migrations.

Risk: If the application database user is compromised, the attacker could:

Drop tables or entire schema
Modify other databases on the same server
Access sensitive data from other applications

Fix: Add migration for application-specific role with minimal privileges:

-- Create application role with minimal privileges
CREATE ROLE guardrail_app WITH LOGIN PASSWORD 'strong_random_password';

-- Grant only necessary privileges
GRANT CONNECT ON DATABASE guardrails TO guardrail_app;
GRANT USAGE ON SCHEMA public TO guardrail_app;
GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO guardrail_app;
GRANT USAGE ON ALL SEQUENCES IN SCHEMA public TO guardrail_app;

-- Explicitly deny dangerous operations
REVOKE CREATE ON SCHEMA public FROM guardrail_app;
REVOKE ALL ON TABLE schema_migrations FROM guardrail_app; -- Protect migrations

4. Audit Logging - Partial Implementation (Low)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/*.go Severity: Low

Issue: While an audit_log table is defined in migrations (001_create_tables.up.sql lines 62-77), no database operations are actually writing to it.

Current State: Audit log table exists but is not populated by the application.

Risk: Security events (unauthorized access attempts, data modifications) are not tracked at the database level.

Fix: Add audit logging wrapper for sensitive operations:

// In each store file, add audit logging
func (s *FailureStore) Create(ctx context.Context, f *models.FailureEntry) error {
    // ... existing transaction code ...

    // Log to audit table
    _, err = tx.ExecContext(ctx, `
        INSERT INTO audit_log (event_id, event_type, severity, actor, action, resource, status, details)
        VALUES ($1, 'failure_created', 'info', $2, 'CREATE', $3, 'success', $4)
    `, generateEventID(), getCurrentActor(ctx), f.FailureID, toJSON(f))

    // ... commit ...
}

5. Search Query Sanitization - Regex Limitations (Low)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/documents.go Line: 275-293 Severity: Low

Issue: The sanitizeSearchQuery function uses a regex that may not catch all FTS (Full Text Search) injection attempts.

Current Code:

func sanitizeSearchQuery(query string) (string, error) {
    safe := regexp.MustCompile(`[^a-zA-Z0-9\s\-\*"&\|]`)
    cleaned := safe.ReplaceAllString(query, "")
    // ...
}

Risk: Sophisticated attackers might bypass the regex using Unicode characters or other encoding tricks.

Fix: Use allow-list approach with strict validation:

func sanitizeSearchQuery(query string) (string, error) {
    if len(query) > maxSearchQueryLength {
        return "", fmt.Errorf("query too long (max %d chars)", maxSearchQueryLength)
    }

    // Use PostgreSQL's plainto_tsquery which safely handles user input
    // Instead of manual sanitization, rely on parameterized query
    // The current implementation using plainto_tsquery in SQL is actually correct
    // Just ensure the query length check happens before the SQL call

    // Additional check: block common SQL keywords
    lowerQuery := strings.ToLower(query)
    blocked := []string{";", "--", "/*", "*/", "drop", "delete", "insert", "update"}
    for _, b := range blocked {
        if strings.Contains(lowerQuery, b) {
            return "", fmt.Errorf("invalid characters in query")
        }
    }

    return query, nil
}

6. Error Message Information Disclosure (Low)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/*.go (multiple files) Severity: Low

Issue: Database error messages may leak sensitive information about the database structure.

Example from documents.go:

return nil, fmt.Errorf("failed to get document: %w", err)

Risk: Wrapped errors from the database driver could expose:

Table names
Column names
Database constraints
Internal file paths

Fix: Implement error classification:

func sanitizeDBError(err error, operation string) error {
    if err == nil {
        return nil
    }

    // Log full error internally
    slog.Error("database error",
        "operation", operation,
        "error", err,
    )

    // Return generic error to caller
    switch {
    case errors.Is(err, sql.ErrNoRows):
        return fmt.Errorf("resource not found")
    case IsUniqueViolation(err):
        return fmt.Errorf("resource already exists")
    case IsForeignKeyViolation(err):
        return fmt.Errorf("invalid reference")
    default:
        return fmt.Errorf("database operation failed")
    }
}

7. Connection String Password Exposure in Logs (Low)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/postgres.go Line: 56-60 Severity: Low

Issue: Connection info is logged including host and database name, which could be sensitive.

Current Code:

slog.Info("Database connected",
    "max_conns", maxConns,
    "host", cfg.DBHost,
    "database", cfg.DBName,
)

Risk: While password is not logged, exposing internal hostnames and database names aids reconnaissance.

Fix:

slog.Info("Database connected",
    "max_conns", maxConns,
    // Omit host and database names in production
)

8. Migration Down Scripts - Data Loss Risk (Info)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/001_create_tables.down.sql Severity: Info

Issue: Down migrations use CASCADE which could unintentionally drop dependent objects.

Current Code:

DROP TABLE IF EXISTS audit_log CASCADE;
DROP TABLE IF EXISTS failure_registry CASCADE;
-- etc.

Note: This is acceptable for development/testing but should be used with extreme caution in production.

Recommendation: Document that down migrations should be tested thoroughly and run only during maintenance windows with backups.

9. Array Parameter Handling (Info)

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/failures.go Line: 208-243 Severity: Info

Status: SECURE - The code properly uses parameterized queries with PostgreSQL array parameters.

Code:

rows, err := s.db.QueryContext(ctx, query, files)  // files is []string

The pgx driver handles array parameterization correctly, preventing SQL injection through array elements.

Positive Security Findings

1. SQL Injection Prevention - EXCELLENT

All database queries use parameterized statements with numbered placeholders ($1, $2, etc.). No string concatenation is used for query construction.

Files: All store files (documents.go, rules.go, failures.go, projects.go)

2. Transaction Safety - EXCELLENT

All write operations (CREATE, UPDATE, DELETE) use proper transactions with:

Explicit BEGIN
Deferred ROLLBACK for cleanup
Explicit COMMIT on success
Error handling for both operations

3. Input Validation - GOOD

Models have comprehensive Validate() methods:

/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/document.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/project.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/rule.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/failure.go

4. Dynamic Query Building - SECURE

The FailureStore.List() method uses a type-safe switch statement instead of string concatenation for optional filters.

File: /mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/failures.go lines 46-120

5. Connection Pool Security - GOOD

Connection pooling is properly configured with:

Max connection limits
Connection lifetime limits
Idle connection timeouts
Health checks with retry logic

Recommendations by Priority

Immediate (Address within 1 week)

Add statement_timeout configuration to prevent runaway queries
Implement production database role with minimal privileges
Add SSL certificate configuration options for verify modes

Short-term (Address within 1 month)

Implement audit logging for all CRUD operations
Sanitize error messages to prevent information disclosure
Review and harden search query sanitization

Long-term (Address within 3 months)

Implement database activity monitoring
Set up automated backup encryption verification
Add query performance monitoring and slow query alerts

Compliance Notes

Requirement	Status	Notes
SQL Injection Prevention	PASS	All queries parameterized
Transaction Safety	PASS	Proper commit/rollback handling
Input Validation	PASS	Model validation in place
Audit Logging	PARTIAL	Table exists but not populated
Least Privilege	FAIL	No role-based permissions defined
Connection Encryption	PARTIAL	SSL mode configurable but not enforced
Query Timeouts	FAIL	No statement timeout configured

Appendix: Files Reviewed

Go Source Files

/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/postgres.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/tx.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/failures.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/documents.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/rules.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/projects.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/metrics.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/config/config.go

Model Files

/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/document.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/project.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/rule.go
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/models/failure.go

SQL Migration Files

/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/001_create_tables.up.sql
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/001_create_tables.down.sql
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/002_add_indexes.up.sql
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/003_add_triggers.up.sql
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/004_fix_indexes.up.sql
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/005_schema_versioning.up.sql
/mnt/ollama/git/agent-guardrails-template/mcp-server/internal/database/migrations/006_partition_management.up.sql

Report generated by Database Administrator Agent Follow security best practices and regularly audit database implementations

15 KiB Raw Blame History

Database Security Audit Report

Executive Summary

Findings Summary

Detailed Findings

1. Connection Security - Missing TLS Certificate Verification (Medium)

2. Query Timeout Handling - Missing Statement Timeouts (Medium)

3. Schema Permissions - Missing Principle of Least Privilege (Medium)

4. Audit Logging - Partial Implementation (Low)

5. Search Query Sanitization - Regex Limitations (Low)

6. Error Message Information Disclosure (Low)

7. Connection String Password Exposure in Logs (Low)

8. Migration Down Scripts - Data Loss Risk (Info)

9. Array Parameter Handling (Info)

Positive Security Findings

1. SQL Injection Prevention - EXCELLENT

2. Transaction Safety - EXCELLENT

3. Input Validation - GOOD

4. Dynamic Query Building - SECURE

5. Connection Pool Security - GOOD

Recommendations by Priority

Immediate (Address within 1 week)

Short-term (Address within 1 month)

Long-term (Address within 3 months)

Compliance Notes

Appendix: Files Reviewed

Go Source Files

Model Files

SQL Migration Files

15 KiB

Raw Blame History