feat(internal/wireguard): opportunistic kernelspace

- Auto detect if kernelspace implementation is available - Fallback to Go userspace implementation if kernel is not available
2025-12-10 00:09:53 -06:00 · 2021-12-14 11:03:36 +00:00 · 2021-12-14 11:03:36 +00:00 · cfa3bb3b64
commit cfa3bb3b64
parent b9a9319cb4
14 changed files with 229 additions and 79 deletions
--- a/README.md
+++ b/README.md
@ -64,7 +64,7 @@ using Go, OpenVPN or Wireguard, iptables, DNS over TLS, ShadowSocks and an HTTP
 - Based on Alpine 3.14 for a small Docker image of 33MB
 - Supports: **Cyberghost**, **ExpressVPN**, **FastestVPN**, **HideMyAss**, **IPVanish**, **IVPN**, **Mullvad**, **NordVPN**, **Perfect Privacy**, **Privado**, **Private Internet Access**, **PrivateVPN**, **ProtonVPN**, **PureVPN**,  **Surfshark**, **TorGuard**, **VPNUnlimited**, **Vyprvpn**, **WeVPN**, **Windscribe** servers
 - Supports OpenVPN for all providers listed
- Supports Wireguard
+- Supports Wireguard both kernelspace and userspace
  - For **Mullvad**, **Ivpn** and **Windscribe**
  - For **Torguard**, **VPN Unlimited** and **WeVPN** using [the custom provider](https://github.com/qdm12/gluetun/wiki/Custom-provider)
  - For custom Wireguard configurations using [the custom provider](https://github.com/qdm12/gluetun/wiki/Custom-provider)
--- a/go.mod
+++ b/go.mod
@ -14,7 +14,7 @@ require (
 	github.com/qdm12/ss-server v0.3.0
 	github.com/qdm12/updated v0.0.0-20210603204757-205acfe6937e
 	github.com/stretchr/testify v1.7.0
-	github.com/vishvananda/netlink v1.1.0
+	github.com/vishvananda/netlink v1.1.1-0.20211129163951-9ada19101fc5
 	golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c
 	golang.zx2c4.com/wireguard v0.0.0-20210805125648-3957e9b9dd19
 	golang.zx2c4.com/wireguard/wgctrl v0.0.0-20210803171230-4253848d036c
@ -34,7 +34,7 @@ require (
 	github.com/mr-tron/base58 v1.2.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/riobard/go-bloom v0.0.0-20200614022211-cdc8013cb5b3 // indirect
-	github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df // indirect
+	github.com/vishvananda/netns v0.0.0-20200728191858-db3c7e526aae // indirect
 	go4.org/intern v0.0.0-20210108033219-3eb7198706b2 // indirect
 	go4.org/unsafe/assume-no-moving-gc v0.0.0-20201222180813-1025295fd063 // indirect
 	golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97 // indirect
--- a/go.sum
+++ b/go.sum
@ -130,10 +130,10 @@ github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UV
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/vishvananda/netlink v1.1.0 h1:1iyaYNBLmP6L0220aDnYQpo1QEV4t4hJ+xEEhhJH8j0=
-github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYppBueQtXaqoE=
-github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df h1:OviZH7qLw/7ZovXvuNyL3XQl8UFofeikI1NW1Gypu7k=
-github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df/go.mod h1:JP3t17pCcGlemwknint6hfoeCVQrEMVwxRLRjXpq+BU=
+github.com/vishvananda/netlink v1.1.1-0.20211129163951-9ada19101fc5 h1:b/k/BVWzWRS5v6AB0gf2ckFSbFsHN5jR0HoNso1pN+w=
+github.com/vishvananda/netlink v1.1.1-0.20211129163951-9ada19101fc5/go.mod h1:twkDnbuQxJYemMlGd4JFIcuhgX83tXhKS2B/PRMpOho=
+github.com/vishvananda/netns v0.0.0-20200728191858-db3c7e526aae h1:4hwBBUfQCFe3Cym0ZtKyq7L16eZUtYKs+BaHDN6mAns=
+github.com/vishvananda/netns v0.0.0-20200728191858-db3c7e526aae/go.mod h1:DD4vA1DwXk04H54A1oHXtwZmA0grkVMdPxx/VGLCah0=
 github.com/xanzy/ssh-agent v0.2.1/go.mod h1:mLlQY/MoOhWBj+gOGMQkOeiEvkx+8pJSI+0Bx9h2kr4=
 github.com/yl2chen/cidranger v1.0.2/go.mod h1:9U1yz7WPYDwf0vpNWFaeRh0bjwz5RVgRy/9UEQfHl0g=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
@ -185,7 +185,6 @@ golang.org/x/sys v0.0.0-20190221075227-b4e8571b14e0/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190411185658-b44545bcd369/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190826190057-c7b8b68b1456/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190924154521-2837fb4f24fe/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@ -193,7 +192,9 @@ golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200217220822-9197077df867/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200728102440-3e129f6d46b1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201009025420-dfb3f7c4e634/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201118182958-a01c418693c7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
--- a/internal/netlink/family.go
+++ b/internal/netlink/family.go
@ -1,6 +1,10 @@
 package netlink

-import "github.com/vishvananda/netlink"
+import (
+	"fmt"
+
+	"github.com/vishvananda/netlink"
+)

 //nolint:revive
 const (
@ -8,3 +12,20 @@ const (
 	FAMILY_V4  = netlink.FAMILY_V4
 	FAMILY_V6  = netlink.FAMILY_V6
 )
+
+type WireguardChecker interface {
+	IsWireguardSupported() (ok bool, err error)
+}
+
+func (n *NetLink) IsWireguardSupported() (ok bool, err error) {
+	families, err := netlink.GenlFamilyList()
+	if err != nil {
+		return false, fmt.Errorf("cannot list gen 1 families: %w", err)
+	}
+	for _, family := range families {
+		if family.Name == "wireguard" {
+			return true, nil
+		}
+	}
+	return false, nil
+}
--- a/internal/netlink/family_test.go
+++ b/internal/netlink/family_test.go
@ -0,0 +1,21 @@
+package netlink
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_NetLink_IsWireguardSupported(t *testing.T) {
+	t.Skip() // TODO unskip once the data race problem with netlink.GenlFamilyList() is fixed
+
+	t.Parallel()
+	netLink := &NetLink{}
+	ok, err := netLink.IsWireguardSupported()
+	require.NoError(t, err)
+	if ok { // cannot assert since this depends on kernel
+		t.Log("wireguard is supported")
+	} else {
+		t.Log("wireguard is not supported")
+	}
+}
--- a/internal/netlink/interface.go
+++ b/internal/netlink/interface.go
@ -9,4 +9,5 @@ type NetLinker interface {
 	Linker
 	Router
 	Ruler
+	WireguardChecker
 }
--- a/internal/netlink/link.go
+++ b/internal/netlink/link.go
@ -3,8 +3,9 @@ package netlink
 import "github.com/vishvananda/netlink"

 type (
-	Link   = netlink.Link
-	Bridge = netlink.Bridge
+	Link      = netlink.Link
+	Bridge    = netlink.Bridge
+	Wireguard = netlink.Wireguard
 )

 var _ Linker = (*NetLink)(nil)
--- a/internal/netlink/mock_netlink/interface.go
+++ b/internal/netlink/mock_netlink/interface.go
@ -63,6 +63,21 @@ func (mr *MockNetLinkerMockRecorder) AddrList(arg0, arg1 interface{}) *gomock.Ca
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "AddrList", reflect.TypeOf((*MockNetLinker)(nil).AddrList), arg0, arg1)
 }

+// IsWireguardSupported mocks base method.
+func (m *MockNetLinker) IsWireguardSupported() (bool, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "IsWireguardSupported")
+	ret0, _ := ret[0].(bool)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// IsWireguardSupported indicates an expected call of IsWireguardSupported.
+func (mr *MockNetLinkerMockRecorder) IsWireguardSupported() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "IsWireguardSupported", reflect.TypeOf((*MockNetLinker)(nil).IsWireguardSupported))
+}
+
 // LinkAdd mocks base method.
 func (m *MockNetLinker) LinkAdd(arg0 netlink.Link) error {
 	m.ctrl.T.Helper()
--- a/internal/routing/rules_test.go
+++ b/internal/routing/rules_test.go
@ -88,7 +88,7 @@ func Test_Routing_addIPRule(t *testing.T) {
 				ruleToAdd: makeIPRule(t, makeIPNet(t, 1), makeIPNet(t, 2), 99, 99),
 				err:       errDummy,
 			},
-			err: errors.New("dummy error: for rule: ip rule 99: from 1.1.1.0/24 table 99"),
+			err: errors.New("dummy error: for rule: ip rule 99: from 1.1.1.0/24 to 2.2.2.0/24 table 99"),
 		},
 		"add rule success": {
 			src:      makeIPNet(t, 1),
@ -193,7 +193,7 @@ func Test_Routing_deleteIPRule(t *testing.T) {
 				ruleToDel: makeIPRule(t, makeIPNet(t, 1), makeIPNet(t, 2), 99, 99),
 				err:       errDummy,
 			},
-			err: errors.New("dummy error: for rule: ip rule 99: from 1.1.1.0/24 table 99"),
+			err: errors.New("dummy error: for rule: ip rule 99: from 1.1.1.0/24 to 2.2.2.0/24 table 99"),
 		},
 		"rule deleted": {
 			src:      makeIPNet(t, 1),
--- a/internal/wireguard/netlinker.go
+++ b/internal/wireguard/netlinker.go
@ -10,9 +10,11 @@ type NetLinker interface {
 	RouteAdd(route *netlink.Route) error
 	RuleAdd(rule *netlink.Rule) error
 	RuleDel(rule *netlink.Rule) error
+	LinkAdd(link netlink.Link) (err error)
 	LinkList() (links []netlink.Link, err error)
 	LinkByName(name string) (link netlink.Link, err error)
 	LinkSetUp(link netlink.Link) error
 	LinkSetDown(link netlink.Link) error
 	LinkDel(link netlink.Link) error
+	IsWireguardSupported() (ok bool, err error)
 }
--- a/internal/wireguard/netlinker_mock_test.go
+++ b/internal/wireguard/netlinker_mock_test.go
@ -48,6 +48,35 @@ func (mr *MockNetLinkerMockRecorder) AddrAdd(arg0, arg1 interface{}) *gomock.Cal
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "AddrAdd", reflect.TypeOf((*MockNetLinker)(nil).AddrAdd), arg0, arg1)
 }

+// IsWireguardSupported mocks base method.
+func (m *MockNetLinker) IsWireguardSupported() (bool, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "IsWireguardSupported")
+	ret0, _ := ret[0].(bool)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// IsWireguardSupported indicates an expected call of IsWireguardSupported.
+func (mr *MockNetLinkerMockRecorder) IsWireguardSupported() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "IsWireguardSupported", reflect.TypeOf((*MockNetLinker)(nil).IsWireguardSupported))
+}
+
+// LinkAdd mocks base method.
+func (m *MockNetLinker) LinkAdd(arg0 netlink.Link) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "LinkAdd", arg0)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// LinkAdd indicates an expected call of LinkAdd.
+func (mr *MockNetLinkerMockRecorder) LinkAdd(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "LinkAdd", reflect.TypeOf((*MockNetLinker)(nil).LinkAdd), arg0)
+}
+
 // LinkByName mocks base method.
 func (m *MockNetLinker) LinkByName(arg0 string) (netlink.Link, error) {
 	m.ctrl.T.Helper()
--- a/internal/wireguard/route_test.go
+++ b/internal/wireguard/route_test.go
@ -53,7 +53,7 @@ func Test_Wireguard_addRoute(t *testing.T) {
 				Table:     firewallMark,
 			},
 			routeAddErr: errDummy,
-			err:         errors.New("dummy: when adding route: {Ifindex: 88 Dst: 1.2.3.4/32 Src: <nil> Gw: <nil> Flags: [] Table: 51820}"), //nolint:lll
+			err:         errors.New("dummy: when adding route: {Ifindex: 88 Dst: 1.2.3.4/32 Src: <nil> Gw: <nil> Flags: [] Table: 51820 Realm: 0}"), //nolint:lll
 		},
 	}

--- a/internal/wireguard/rule_test.go
+++ b/internal/wireguard/rule_test.go
@ -51,7 +51,7 @@ func Test_Wireguard_addRule(t *testing.T) {
 				SuppressPrefixlen: -1,
 			},
 			ruleAddErr: errDummy,
-			err:        errors.New("dummy: when adding rule: ip rule 987: from <nil> table 456"),
+			err:        errors.New("dummy: when adding rule: ip rule 987: from all to all table 456"),
 		},
 		"rule delete error": {
 			expectedRule: &netlink.Rule{
@ -66,7 +66,7 @@ func Test_Wireguard_addRule(t *testing.T) {
 				SuppressPrefixlen: -1,
 			},
 			ruleDelErr: errDummy,
-			cleanupErr: errors.New("dummy: when deleting rule: ip rule 987: from <nil> table 456"),
+			cleanupErr: errors.New("dummy: when deleting rule: ip rule 987: from all to all table 456"),
 		},
 	}

--- a/internal/wireguard/run.go
+++ b/internal/wireguard/run.go
@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"

+	"github.com/qdm12/gluetun/internal/netlink"
 	"golang.zx2c4.com/wireguard/conn"
 	"golang.zx2c4.com/wireguard/device"
 	"golang.zx2c4.com/wireguard/ipc"
@ -15,7 +16,9 @@ import (

 var (
 	ErrDetectIPv6        = errors.New("cannot detect IPv6 support")
+	ErrDetectKernel      = errors.New("cannot detect Kernel support")
 	ErrCreateTun         = errors.New("cannot create TUN device")
+	ErrAddLink           = errors.New("cannot add Wireguard link")
 	ErrFindLink          = errors.New("cannot find link")
 	ErrFindDevice        = errors.New("cannot find Wireguard device")
 	ErrUAPISocketOpening = errors.New("cannot open UAPI socket")
@ -23,6 +26,7 @@ var (
 	ErrUAPIListen        = errors.New("cannot listen on UAPI socket")
 	ErrAddAddress        = errors.New("cannot add address to wireguard interface")
 	ErrConfigure         = errors.New("cannot configure wireguard interface")
+	ErrDeviceInfo        = errors.New("cannot get wireguard device information")
 	ErrIfaceUp           = errors.New("cannot set the interface to UP")
 	ErrRouteAdd          = errors.New("cannot add route for interface")
 	ErrRuleAdd           = errors.New("cannot add rule for interface")
@ -41,6 +45,12 @@ func (w *Wireguard) Run(ctx context.Context, waitError chan<- error, ready chan<
 		return
 	}

+	doKernel, err := w.netlink.IsWireguardSupported()
+	if err != nil {
+		waitError <- fmt.Errorf("%w: %s", ErrDetectKernel, err)
+		return
+	}
+
 	client, err := wgctrl.New()
 	if err != nil {
 		waitError <- fmt.Errorf("%w: %s", ErrWgctrlOpen, err)
@ -52,62 +62,21 @@ func (w *Wireguard) Run(ctx context.Context, waitError chan<- error, ready chan<

 	defer closers.cleanup(w.logger)

-	tun, err := tun.CreateTUN(w.settings.InterfaceName, device.DefaultMTU)
-	if err != nil {
-		waitError <- fmt.Errorf("%w: %s", ErrCreateTun, err)
-		return
+	setupFunction := setupUserSpace
+	if doKernel {
+		w.logger.Info("Using available kernelspace implementation")
+		setupFunction = setupKernelSpace
+	} else {
+		w.logger.Info("Using userspace implementation since Kernel support does not exist")
 	}

-	closers.add("closing TUN device", stepSeven, tun.Close)
-
-	tunName, err := tun.Name()
+	link, waitAndCleanup, err := setupFunction(ctx,
+		w.settings.InterfaceName, w.netlink, &closers, w.logger)
 	if err != nil {
-		waitError <- fmt.Errorf("%w: cannot get TUN name: %s", ErrCreateTun, err)
-		return
-	} else if tunName != w.settings.InterfaceName {
-		waitError <- fmt.Errorf("%w: names don't match: expected %q and got %q",
-			ErrCreateTun, w.settings.InterfaceName, tunName)
+		waitError <- err
 		return
 	}

-	link, err := w.netlink.LinkByName(w.settings.InterfaceName)
-	if err != nil {
-		waitError <- fmt.Errorf("%w: %s: %s", ErrFindLink, w.settings.InterfaceName, err)
-		return
-	}
-
-	bind := conn.NewDefaultBind()
-
-	closers.add("closing bind", stepSeven, bind.Close)
-
-	deviceLogger := makeDeviceLogger(w.logger)
-	device := device.NewDevice(tun, bind, deviceLogger)
-
-	closers.add("closing Wireguard device", stepSix, func() error {
-		device.Close()
-		return nil
-	})
-
-	uapiFile, err := ipc.UAPIOpen(w.settings.InterfaceName)
-	if err != nil {
-		waitError <- fmt.Errorf("%w: %s", ErrUAPISocketOpening, err)
-		return
-	}
-
-	closers.add("closing UAPI file", stepThree, uapiFile.Close)
-
-	uapiListener, err := ipc.UAPIListen(w.settings.InterfaceName, uapiFile)
-	if err != nil {
-		waitError <- fmt.Errorf("%w: %s", ErrUAPIListen, err)
-		return
-	}
-
-	closers.add("closing UAPI listener", stepTwo, uapiListener.Close)
-
-	// acceptAndHandle exits when uapiListener is closed
-	uapiAcceptErrorCh := make(chan error)
-	go acceptAndHandle(uapiListener, device, uapiAcceptErrorCh)
-
 	err = w.addAddresses(link, w.settings.Addresses)
 	if err != nil {
 		waitError <- fmt.Errorf("%w: %s", ErrAddAddress, err)
@ -128,9 +97,6 @@ func (w *Wireguard) Run(ctx context.Context, waitError chan<- error, ready chan<
 	closers.add("shutting down link", stepFour, func() error {
 		return w.netlink.LinkSetDown(link)
 	})
-	closers.add("deleting link", stepFive, func() error {
-		return w.netlink.LinkDel(link)
-	})

 	err = w.addRoute(link, allIPv4(), w.settings.FirewallMark)
 	if err != nil {
@ -158,20 +124,113 @@ func (w *Wireguard) Run(ctx context.Context, waitError chan<- error, ready chan<
 	w.logger.Info("Wireguard is up")
 	ready <- struct{}{}

-	select {
-	case <-ctx.Done():
-		err = ctx.Err()
-	case err = <-uapiAcceptErrorCh:
-		close(uapiAcceptErrorCh)
-	case <-device.Wait():
-		err = ErrDeviceWaited
+	waitError <- waitAndCleanup()
+}
+
+type waitAndCleanupFunc func() error
+
+func setupKernelSpace(ctx context.Context,
+	interfaceName string, netLinker NetLinker,
+	closers *closers, logger Logger) (
+	link netlink.Link, waitAndCleanup waitAndCleanupFunc, err error) {
+	linkAttrs := netlink.LinkAttrs{
+		Name: interfaceName,
+		MTU:  device.DefaultMTU, // TODO
+	}
+	link = &netlink.Wireguard{
+		LinkAttrs: linkAttrs,
+	}
+	err = netLinker.LinkAdd(link)
+	if err != nil {
+		return nil, nil, fmt.Errorf("%w: %s", ErrAddLink, err)
+	}
+	closers.add("deleting link", stepFive, func() error {
+		return netLinker.LinkDel(link)
+	})
+
+	waitAndCleanup = func() error {
+		<-ctx.Done()
+		closers.cleanup(logger)
+		return ctx.Err()
 	}

-	closers.cleanup(w.logger)
+	return link, waitAndCleanup, nil
+}

-	<-uapiAcceptErrorCh // wait for acceptAndHandle to exit
+func setupUserSpace(ctx context.Context,
+	interfaceName string, netLinker NetLinker,
+	closers *closers, logger Logger) (
+	link netlink.Link, waitAndCleanup waitAndCleanupFunc, err error) {
+	tun, err := tun.CreateTUN(interfaceName, device.DefaultMTU)
+	if err != nil {
+		return nil, nil, fmt.Errorf("%w: %s", ErrCreateTun, err)
+	}

-	waitError <- err
+	closers.add("closing TUN device", stepSeven, tun.Close)
+
+	tunName, err := tun.Name()
+	if err != nil {
+		return nil, nil, fmt.Errorf("%w: cannot get TUN name: %s", ErrCreateTun, err)
+	} else if tunName != interfaceName {
+		return nil, nil, fmt.Errorf("%w: names don't match: expected %q and got %q",
+			ErrCreateTun, interfaceName, tunName)
+	}
+
+	link, err = netLinker.LinkByName(interfaceName)
+	if err != nil {
+		return nil, nil, fmt.Errorf("%w: %s: %s", ErrFindLink, interfaceName, err)
+	}
+	closers.add("deleting link", stepFive, func() error {
+		return netLinker.LinkDel(link)
+	})
+
+	bind := conn.NewDefaultBind()
+
+	closers.add("closing bind", stepSeven, bind.Close)
+
+	deviceLogger := makeDeviceLogger(logger)
+	device := device.NewDevice(tun, bind, deviceLogger)
+
+	closers.add("closing Wireguard device", stepSix, func() error {
+		device.Close()
+		return nil
+	})
+
+	uapiFile, err := ipc.UAPIOpen(interfaceName)
+	if err != nil {
+		return nil, nil, fmt.Errorf("%w: %s", ErrUAPISocketOpening, err)
+	}
+
+	closers.add("closing UAPI file", stepThree, uapiFile.Close)
+
+	uapiListener, err := ipc.UAPIListen(interfaceName, uapiFile)
+	if err != nil {
+		return nil, nil, fmt.Errorf("%w: %s", ErrUAPIListen, err)
+	}
+
+	closers.add("closing UAPI listener", stepTwo, uapiListener.Close)
+
+	// acceptAndHandle exits when uapiListener is closed
+	uapiAcceptErrorCh := make(chan error)
+	go acceptAndHandle(uapiListener, device, uapiAcceptErrorCh)
+	waitAndCleanup = func() error {
+		select {
+		case <-ctx.Done():
+			err = ctx.Err()
+		case err = <-uapiAcceptErrorCh:
+			close(uapiAcceptErrorCh)
+		case <-device.Wait():
+			err = ErrDeviceWaited
+		}
+
+		closers.cleanup(logger)
+
+		<-uapiAcceptErrorCh // wait for acceptAndHandle to exit
+
+		return err
+	}
+
+	return link, waitAndCleanup, nil
 }

 func acceptAndHandle(uapi net.Listener, device *device.Device,