main.c

#include "multics_rings.h"

/**
 * Main program demonstrating Multics ring-based access control
 */
int main() {
    printf("╔════════════════════════════════════════════════════════════════╗\n");
    printf("║        MULTICS RING-BASED ACCESS CONTROL SIMULATION           ║\n");
    printf("╚════════════════════════════════════════════════════════════════╝\n\n");
    
    // 5.1.2: Create 4 users, each assigned to a different ring level
    User kernel_user = {
        .name = "root",
        .user_id = 1000,
        .ring_level = RING_0_KERNEL,
        .last_failed_attempt = 0,
        .failed_attempt_count = 0
    };
    
    User system_daemon = {
        .name = "systemd",
        .user_id = 2000,
        .ring_level = RING_1_SYSTEM,
        .last_failed_attempt = 0,
        .failed_attempt_count = 0
    };
    
    User regular_user = {
        .name = "alice",
        .user_id = 3000,
        .ring_level = RING_2_USER,
        .last_failed_attempt = 0,
        .failed_attempt_count = 0
    };
    
    User guest_user = {
        .name = "guest",
        .user_id = 4000,
        .ring_level = RING_3_GUEST,
        .last_failed_attempt = 0,
        .failed_attempt_count = 0
    };
    
    // Display user information
    printf("📋 SYSTEM USERS:\n\n");
    printf("%-15s | %-10s | %s\n", "Username", "User ID", "Ring Level");
    printf("────────────────────────────────────────────────────────────────\n");
    printf("%-15s | %-10d | %s\n", kernel_user.name, kernel_user.user_id, get_ring_name(kernel_user.ring_level));
    printf("%-15s | %-10d | %s\n", system_daemon.name, system_daemon.user_id, get_ring_name(system_daemon.ring_level));
    printf("%-15s | %-10d | %s\n", regular_user.name, regular_user.user_id, get_ring_name(regular_user.ring_level));
    printf("%-15s | %-10d | %s\n", guest_user.name, guest_user.user_id, get_ring_name(guest_user.ring_level));
    
    printf("\n\n");
    printf("╔════════════════════════════════════════════════════════════════╗\n");
    printf("║                    TEST CASE SCENARIOS                         ║\n");
    printf("╚════════════════════════════════════════════════════════════════╝\n");
    
    // 5.2.2: Test Case 1 - Ring 3 user trying to access Ring 0 (should fail)
    printf("\n\n📝 TEST 1: Guest user attempting to access Kernel functions\n");
    printf("Expected: DENIED (Ring 3 cannot access Ring 0)\n");
    execute_ring_operation(&guest_user, RING_0_KERNEL, "Modify kernel memory");
    
    // 5.2.2: Test Case 2 - Ring 3 user trying to access Ring 1 (should fail)
    printf("\n\n📝 TEST 2: Guest user attempting to access System Services\n");
    printf("Expected: DENIED (Ring 3 cannot access Ring 1)\n");
    execute_ring_operation(&guest_user, RING_1_SYSTEM, "Start system daemon");
    
    // Test Case 3 - Ring 3 user accessing their own ring (should succeed)
    printf("\n\n📝 TEST 3: Guest user accessing their own ring level\n");
    printf("Expected: GRANTED (Same ring access)\n");
    execute_ring_operation(&guest_user, RING_3_GUEST, "Run sandboxed application");
    
    // Test Case 4 - Ring 2 user accessing Ring 1 via gate (should succeed - adjacent)
    printf("\n\n📝 TEST 4: Regular user accessing System Services via gate\n");
    printf("Expected: GRANTED (Adjacent ring access)\n");
    execute_ring_operation(&regular_user, RING_1_SYSTEM, "Request system service");
    
    // Test Case 5 - Ring 2 user trying to access Ring 0 (should fail - non-adjacent)
    printf("\n\n📝 TEST 5: Regular user attempting direct kernel access\n");
    printf("Expected: DENIED (Non-adjacent ring)\n");
    execute_ring_operation(&regular_user, RING_0_KERNEL, "Execute privileged instruction");
    
    // Test Case 6 - Ring 0 user accessing any ring (should succeed)
    printf("\n\n📝 TEST 6: Kernel user accessing lower privilege rings\n");
    printf("Expected: GRANTED (Kernel has access to all rings)\n");
    execute_ring_operation(&kernel_user, RING_3_GUEST, "Inspect guest process");
    
    // Test Case 7 - Multiple failed attempts to demonstrate rate limiting
    printf("\n\n📝 TEST 7: Demonstrating rate limiting and covert channel protection\n");
    printf("Attempting multiple unauthorized accesses...\n");
    for (int i = 0; i < 7; i++) {
        printf("\n--- Attempt %d ---\n", i + 1);
        execute_ring_operation(&guest_user, RING_0_KERNEL, "Unauthorized kernel access");
    }
    
    // Test Case 8 - System daemon accessing kernel via gate
    printf("\n\n📝 TEST 8: System daemon accessing kernel via gate\n");
    printf("Expected: GRANTED (Adjacent ring access)\n");
    execute_ring_operation(&system_daemon, RING_0_KERNEL, "Request kernel service");
    
    // Test Case 9 - User accessing lower privilege ring
    printf("\n\n📝 TEST 9: Regular user accessing guest ring\n");
    printf("Expected: GRANTED (Access to lower privilege ring)\n");
    execute_ring_operation(&regular_user, RING_3_GUEST, "Monitor guest process");
    
    // Display final statistics
    display_statistics();
    
    printf("\n✓ All test cases completed!\n");
    printf("📄 Access logs saved to: %s\n\n", "access_log.txt");
    
    return 0;
}