Add support for autoApprovers ACL

acls_types.go

@@ -11,11 +11,12 @@ import (
 
 // ACLPolicy represents a Tailscale ACL Policy.
 type ACLPolicy struct {
-	Groups    Groups    `json:"groups"    yaml:"groups"`
-	Hosts     Hosts     `json:"hosts"     yaml:"hosts"`
-	TagOwners TagOwners `json:"tagOwners" yaml:"tagOwners"`
-	ACLs      []ACL     `json:"acls"      yaml:"acls"`
-	Tests     []ACLTest `json:"tests"     yaml:"tests"`
+	Groups        Groups        `json:"groups"        yaml:"groups"`
+	Hosts         Hosts         `json:"hosts"         yaml:"hosts"`
+	TagOwners     TagOwners     `json:"tagOwners"     yaml:"tagOwners"`
+	ACLs          []ACL         `json:"acls"          yaml:"acls"`
+	Tests         []ACLTest     `json:"tests"         yaml:"tests"`
+	AutoApprovers AutoApprovers `json:"autoApprovers" yaml:"autoApprovers"`
 }
 
 // ACL is a basic rule for the ACL Policy.
@@ -42,6 +43,13 @@ type ACLTest struct {
 	Deny   []string `json:"deny,omitempty" yaml:"deny,omitempty"`
 }
 
+// AutoApprovers specify which users (namespaces?), groups or tags have their advertised routes
+// or exit node status automatically enabled.
+type AutoApprovers struct {
+	Routes   map[string][]string `json:"routes"   yaml:"routes"`
+	ExitNode []string            `json:"exitNode" yaml:"exitNode"`
+}
+
 // UnmarshalJSON allows to parse the Hosts directly into netip objects.
 func (hosts *Hosts) UnmarshalJSON(data []byte) error {
 	newHosts := Hosts{}
@@ -100,3 +108,28 @@ func (policy ACLPolicy) IsZero() bool {
 
 	return false
 }
+
+// Returns the list of autoApproving namespaces, groups or tags for a given IPPrefix.
+func (autoApprovers *AutoApprovers) GetRouteApprovers(
+	prefix netip.Prefix,
+) ([]string, error) {
+	if prefix.Bits() == 0 {
+		return autoApprovers.ExitNode, nil // 0.0.0.0/0, ::/0 or equivalent
+	}
+
+	approverAliases := []string{}
+
+	for autoApprovedPrefix, autoApproverAliases := range autoApprovers.Routes {
+		autoApprovedPrefix, err := netip.ParsePrefix(autoApprovedPrefix)
+		if err != nil {
+			return nil, err
+		}
+
+		if autoApprovedPrefix.Bits() >= prefix.Bits() &&
+			autoApprovedPrefix.Contains(prefix.Masked().Addr()) {
+			approverAliases = append(approverAliases, autoApproverAliases...)
+		}
+	}
+
+	return approverAliases, nil
+}

machine.go

@@ -949,6 +949,64 @@ func (h *Headscale) EnableRoutes(machine *Machine, routeStrs ...string) error {
 	return nil
 }
 
+// Enabled any routes advertised by a machine that match the ACL autoApprovers policy.
+func (h *Headscale) EnableAutoApprovedRoutes(machine *Machine) {
+	if len(machine.IPAddresses) == 0 {
+		return // This machine has no IPAddresses, so can't possibly match any autoApprovers ACLs
+	}
+
+	approvedRoutes := make([]netip.Prefix, 0, len(machine.HostInfo.RoutableIPs))
+	thisMachine := []Machine{*machine}
+
+	for _, advertisedRoute := range machine.HostInfo.RoutableIPs {
+		if contains(machine.EnabledRoutes, advertisedRoute) {
+			continue // Skip routes that are already enabled for the node
+		}
+
+		routeApprovers, err := h.aclPolicy.AutoApprovers.GetRouteApprovers(
+			advertisedRoute,
+		)
+		if err != nil {
+			log.Err(err).
+				Str("advertisedRoute", advertisedRoute.String()).
+				Uint64("machineId", machine.ID).
+				Msg("Failed to resolve autoApprovers for advertised route")
+
+			return
+		}
+
+		for _, approvedAlias := range routeApprovers {
+			if approvedAlias == machine.Namespace.Name {
+				approvedRoutes = append(approvedRoutes, advertisedRoute)
+			} else {
+				approvedIps, err := expandAlias(thisMachine, *h.aclPolicy, approvedAlias, h.cfg.OIDC.StripEmaildomain)
+				if err != nil {
+					log.Err(err).
+						Str("alias", approvedAlias).
+						Msg("Failed to expand alias when processing autoApprovers policy")
+
+					return
+				}
+
+				// approvedIPs should contain all of machine's IPs if it matches the rule, so check for first
+				if contains(approvedIps, machine.IPAddresses[0].String()) {
+					approvedRoutes = append(approvedRoutes, advertisedRoute)
+				}
+			}
+		}
+	}
+
+	for _, approvedRoute := range approvedRoutes {
+		if !contains(machine.EnabledRoutes, approvedRoute) {
+			log.Info().
+				Str("route", approvedRoute.String()).
+				Uint64("client", machine.ID).
+				Msg("Enabling autoApproved route for client")
+			machine.EnabledRoutes = append(machine.EnabledRoutes, approvedRoute)
+		}
+	}
+}
+
 func (machine *Machine) RoutesToProto() *v1.Routes {
 	availableRoutes := machine.GetAdvertisedRoutes()
 

machine_test.go

@@ -1050,3 +1050,44 @@ func TestHeadscale_GenerateGivenName(t *testing.T) {
 		})
 	}
 }
+
+func (s *Suite) TestAutoApproveRoutes(c *check.C) {
+	err := app.LoadACLPolicy("./tests/acls/acl_policy_autoapprovers.hujson")
+	c.Assert(err, check.IsNil)
+
+	namespace, err := app.CreateNamespace("test")
+	c.Assert(err, check.IsNil)
+
+	pak, err := app.CreatePreAuthKey(namespace.Name, false, false, nil)
+	c.Assert(err, check.IsNil)
+
+	nodeKey := key.NewNode()
+
+	defaultRoute := netip.MustParsePrefix("0.0.0.0/0")
+	route1 := netip.MustParsePrefix("10.10.0.0/16")
+	route2 := netip.MustParsePrefix("10.11.0.0/16")
+
+	machine := Machine{
+		ID:             0,
+		MachineKey:     "foo",
+		NodeKey:        NodePublicKeyStripPrefix(nodeKey.Public()),
+		DiscoKey:       "faa",
+		Hostname:       "test",
+		NamespaceID:    namespace.ID,
+		RegisterMethod: RegisterMethodAuthKey,
+		AuthKeyID:      uint(pak.ID),
+		HostInfo: HostInfo{
+			RequestTags: []string{"tag:exit"},
+			RoutableIPs: []netip.Prefix{defaultRoute, route1, route2},
+		},
+		IPAddresses: []netip.Addr{netip.MustParseAddr("100.64.0.1")},
+	}
+
+	app.db.Save(&machine)
+
+	machine0ByID, err := app.GetMachineByID(0)
+	c.Assert(err, check.IsNil)
+
+	app.EnableAutoApprovedRoutes(machine0ByID)
+	c.Assert(machine0ByID.GetEnabledRoutes(), check.HasLen, 3)
+}

protocol_common_poll.go

@@ -42,7 +42,11 @@ func (h *Headscale) handlePollCommon(
 				Str("machine", machine.Hostname).
 				Err(err)
 		}
+
+		// update routes with peer information
+		h.EnableAutoApprovedRoutes(machine)
 	}
+
 	// From Tailscale client:
 	//
 	// ReadOnly is whether the client just wants to fetch the MapResponse,

tests/acls/acl_policy_autoapprovers.hujson

@@ -0,0 +1,24 @@
+// This ACL validates autoApprovers support for
+// exit nodes and advertised routes
+
+{
+    "tagOwners": {
+        "tag:exit": ["test"],
+    },
+
+    "groups": {
+        "group:test": ["test"]
+    },
+
+    "acls": [
+        {"action": "accept", "users": ["*"], "ports": ["*:*"]},
+    ],
+
+    "autoApprovers": {
+        "exitNode": ["tag:exit"],
+        "routes": {
+            "10.10.0.0/16": ["group:test"],
+            "10.11.0.0/16": ["test"],
+        }
+    }
+}