Feat firewall controller interface (#740)

Add a standard interface for the client firewall to support ACL.

client/firewall/firewall.go

@@ -0,0 +1,57 @@
+package firewall
+
+import (
+	"net"
+)
+
+// Rule abstraction should be implemented by each firewall manager
+//
+// Each firewall type for different OS can use different type
+// of the properties to hold data of the created rule
+type Rule interface {
+	// GetRuleID returns the rule id
+	GetRuleID() string
+}
+
+// Direction is the direction of the traffic
+type Direction int
+
+const (
+	// DirectionSrc is the direction of the traffic from the source
+	DirectionSrc Direction = iota
+	// DirectionDst is the direction of the traffic from the destination
+	DirectionDst
+)
+
+// Action is the action to be taken on a rule
+type Action int
+
+const (
+	// ActionAccept is the action to accept a packet
+	ActionAccept Action = iota
+	// ActionDrop is the action to drop a packet
+	ActionDrop
+)
+
+// Manager is the high level abstraction of a firewall manager
+//
+// It declares methods which handle actions required by the
+// Netbird client for ACL and routing functionality
+type Manager interface {
+	// AddFiltering rule to the firewall
+	AddFiltering(
+		ip net.IP,
+		port *Port,
+		direction Direction,
+		action Action,
+		comment string,
+	) (Rule, error)
+
+	// DeleteRule from the firewall by rule definition
+	DeleteRule(rule Rule) error
+
+	// Reset firewall to the default state
+	Reset() error
+
+	// TODO: migrate routemanager firewal actions to this interface
+}

client/firewall/iptables/manager_linux.go

@@ -0,0 +1,160 @@
+package iptables
+
+import (
+	"fmt"
+	"net"
+	"strconv"
+	"sync"
+
+	"github.com/coreos/go-iptables/iptables"
+	"github.com/google/uuid"
+
+	fw "github.com/netbirdio/netbird/client/firewall"
+)
+
+const (
+	// ChainFilterName is the name of the chain that is used for filtering by the Netbird client
+	ChainFilterName = "NETBIRD-ACL"
+)
+
+// Manager of iptables firewall
+type Manager struct {
+	mutex sync.Mutex
+
+	ipv4Client *iptables.IPTables
+	ipv6Client *iptables.IPTables
+}
+
+// Create iptables firewall manager
+func Create() (*Manager, error) {
+	m := &Manager{}
+
+	// init clients for booth ipv4 and ipv6
+	ipv4Client, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
+	if err != nil {
+		return nil, fmt.Errorf("iptables is not installed in the system or not supported")
+	}
+	m.ipv4Client = ipv4Client
+
+	ipv6Client, err := iptables.NewWithProtocol(iptables.ProtocolIPv6)
+	if err != nil {
+		return nil, fmt.Errorf("ip6tables is not installed in the system or not supported")
+	}
+	m.ipv6Client = ipv6Client
+
+	if err := m.Reset(); err != nil {
+		return nil, fmt.Errorf("failed to reset firewall: %s", err)
+	}
+
+	return m, nil
+}
+
+// AddFiltering rule to the firewall
+func (m *Manager) AddFiltering(
+	ip net.IP,
+	port *fw.Port,
+	direction fw.Direction,
+	action fw.Action,
+	comment string,
+) (fw.Rule, error) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	client := m.client(ip)
+	ok, err := client.ChainExists("filter", ChainFilterName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to check if chain exists: %s", err)
+	}
+	if !ok {
+		if err := client.NewChain("filter", ChainFilterName); err != nil {
+			return nil, fmt.Errorf("failed to create chain: %s", err)
+		}
+	}
+	if port == nil || port.Values == nil || (port.IsRange && len(port.Values) != 2) {
+		return nil, fmt.Errorf("invalid port definition")
+	}
+	pv := strconv.Itoa(port.Values[0])
+	if port.IsRange {
+		pv += ":" + strconv.Itoa(port.Values[1])
+	}
+	specs := m.filterRuleSpecs("filter", ChainFilterName, ip, pv, direction, action, comment)
+	if err := client.AppendUnique("filter", ChainFilterName, specs...); err != nil {
+		return nil, err
+	}
+	rule := &Rule{
+		id:    uuid.New().String(),
+		specs: specs,
+		v6:    ip.To4() == nil,
+	}
+	return rule, nil
+}
+
+// DeleteRule from the firewall by rule definition
+func (m *Manager) DeleteRule(rule fw.Rule) error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	r, ok := rule.(*Rule)
+	if !ok {
+		return fmt.Errorf("invalid rule type")
+	}
+	client := m.ipv4Client
+	if r.v6 {
+		client = m.ipv6Client
+	}
+	return client.Delete("filter", ChainFilterName, r.specs...)
+}
+
+// Reset firewall to the default state
+func (m *Manager) Reset() error {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	if err := m.reset(m.ipv4Client, "filter", ChainFilterName); err != nil {
+		return fmt.Errorf("clean ipv4 firewall ACL chain: %w", err)
+	}
+	if err := m.reset(m.ipv6Client, "filter", ChainFilterName); err != nil {
+		return fmt.Errorf("clean ipv6 firewall ACL chain: %w", err)
+	}
+	return nil
+}
+
+// reset firewall chain, clear it and drop it
+func (m *Manager) reset(client *iptables.IPTables, table, chain string) error {
+	ok, err := client.ChainExists(table, chain)
+	if err != nil {
+		return fmt.Errorf("failed to check if chain exists: %w", err)
+	}
+	if !ok {
+		return nil
+	}
+	if err := client.ClearChain(table, ChainFilterName); err != nil {
+		return fmt.Errorf("failed to clear chain: %w", err)
+	}
+	return client.DeleteChain(table, ChainFilterName)
+}
+
+// filterRuleSpecs returns the specs of a filtering rule
+func (m *Manager) filterRuleSpecs(
+	table string, chain string, ip net.IP, port string,
+	direction fw.Direction, action fw.Action, comment string,
+) (specs []string) {
+	if direction == fw.DirectionSrc {
+		specs = append(specs, "-s", ip.String())
+	}
+	specs = append(specs, "-p", "tcp", "--dport", port)
+	specs = append(specs, "-j", m.actionToStr(action))
+	return append(specs, "-m", "comment", "--comment", comment)
+}
+
+// client returns corresponding iptables client for the given ip
+func (m *Manager) client(ip net.IP) *iptables.IPTables {
+	if ip.To4() != nil {
+		return m.ipv4Client
+	}
+	return m.ipv6Client
+}
+
+func (m *Manager) actionToStr(action fw.Action) string {
+	if action == fw.ActionAccept {
+		return "ACCEPT"
+	}
+	return "DROP"
+}

client/firewall/iptables/manager_linux_test.go

@@ -0,0 +1,105 @@
+package iptables
+
+import (
+	"net"
+	"testing"
+
+	"github.com/coreos/go-iptables/iptables"
+	fw "github.com/netbirdio/netbird/client/firewall"
+)
+
+func TestNewManager(t *testing.T) {
+	ipv4Client, err := iptables.NewWithProtocol(iptables.ProtocolIPv4)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	manager, err := Create()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var rule1 fw.Rule
+	t.Run("add first rule", func(t *testing.T) {
+		ip := net.ParseIP("10.20.0.2")
+		port := &fw.Port{Proto: fw.PortProtocolTCP, Values: []int{8080}}
+		rule1, err = manager.AddFiltering(ip, port, fw.DirectionDst, fw.ActionAccept, "accept HTTP traffic")
+		if err != nil {
+			t.Errorf("failed to add rule: %v", err)
+		}
+
+		checkRuleSpecs(t, ipv4Client, true, rule1.(*Rule).specs...)
+	})
+
+	var rule2 fw.Rule
+	t.Run("add second rule", func(t *testing.T) {
+		ip := net.ParseIP("10.20.0.3")
+		port := &fw.Port{
+			Proto:  fw.PortProtocolTCP,
+			Values: []int{8043: 8046},
+		}
+		rule2, err = manager.AddFiltering(
+			ip, port, fw.DirectionDst, fw.ActionAccept, "accept HTTPS traffic from ports range")
+		if err != nil {
+			t.Errorf("failed to add rule: %v", err)
+		}
+
+		checkRuleSpecs(t, ipv4Client, true, rule2.(*Rule).specs...)
+	})
+
+	t.Run("delete first rule", func(t *testing.T) {
+		if err := manager.DeleteRule(rule1); err != nil {
+			t.Errorf("failed to delete rule: %v", err)
+		}
+
+		checkRuleSpecs(t, ipv4Client, false, rule1.(*Rule).specs...)
+	})
+
+	t.Run("delete second rule", func(t *testing.T) {
+		if err := manager.DeleteRule(rule2); err != nil {
+			t.Errorf("failed to delete rule: %v", err)
+		}
+
+		checkRuleSpecs(t, ipv4Client, false, rule2.(*Rule).specs...)
+	})
+
+	t.Run("reset check", func(t *testing.T) {
+		// add second rule
+		ip := net.ParseIP("10.20.0.3")
+		port := &fw.Port{Proto: fw.PortProtocolUDP, Values: []int{5353}}
+		_, err = manager.AddFiltering(ip, port, fw.DirectionDst, fw.ActionAccept, "accept Fake DNS traffic")
+		if err != nil {
+			t.Errorf("failed to add rule: %v", err)
+		}
+
+		if err := manager.Reset(); err != nil {
+			t.Errorf("failed to reset: %v", err)
+		}
+
+		ok, err := ipv4Client.ChainExists("filter", ChainFilterName)
+		if err != nil {
+			t.Errorf("failed to drop chain: %v", err)
+		}
+
+		if ok {
+			t.Errorf("chain '%v' still exists after Reset", ChainFilterName)
+		}
+	})
+}
+
+func checkRuleSpecs(t *testing.T, ipv4Client *iptables.IPTables, mustExists bool, rulespec ...string) {
+	exists, err := ipv4Client.Exists("filter", ChainFilterName, rulespec...)
+	if err != nil {
+		t.Errorf("failed to check rule: %v", err)
+		return
+	}
+
+	if !exists && mustExists {
+		t.Errorf("rule '%v' does not exist", rulespec)
+		return
+	}
+	if exists && !mustExists {
+		t.Errorf("rule '%v' exist", rulespec)
+		return
+	}
+}

client/firewall/iptables/rule.go

@@ -0,0 +1,13 @@
+package iptables
+
+// Rule to handle management of rules
+type Rule struct {
+	id    string
+	specs []string
+	v6    bool
+}
+
+// GetRuleID returns the rule id
+func (r *Rule) GetRuleID() string {
+	return r.id
+}

client/firewall/port.go

@@ -0,0 +1,24 @@
+package firewall
+
+// PortProtocol is the protocol of the port
+type PortProtocol string
+
+const (
+	// PortProtocolTCP is the TCP protocol
+	PortProtocolTCP PortProtocol = "tcp"
+
+	// PortProtocolUDP is the UDP protocol
+	PortProtocolUDP PortProtocol = "udp"
+)
+
+// Port of the address for firewall rule
+type Port struct {
+	// IsRange is true Values contains two values, the first is the start port, the second is the end port
+	IsRange bool
+
+	// Values contains one value for single port, multiple values for the list of ports, or two values for the range of ports
+	Values []int
+
+	// Proto is the protocol of the port
+	Proto PortProtocol
+}