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net/tstun: move TAP support out to separate package feature/tap

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Still behind the same ts_omit_tap build tag.

See #14738 for background on the pattern.

Updates #12614

Change-Id: I03fb3d2bf137111e727415bd8e713d8568156ecc
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2025-01-22 18:07:57 -08:00 committed by Brad Fitzpatrick
parent f1710f4a42
commit d6abbc2e61
7 changed files with 85 additions and 20 deletions
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7
cmd/k8s-operator/depaware.txt
View File

@ -140,7 +140,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
github.com/gorilla/securecookie from github.com/gorilla/csrf
github.com/hdevalence/ed25519consensus from tailscale.com/clientupdate/distsign+
L 💣 github.com/illarion/gonotify/v2 from tailscale.com/net/dns
L github.com/insomniacslk/dhcp/dhcpv4 from tailscale.com/net/tstun
L github.com/insomniacslk/dhcp/dhcpv4 from tailscale.com/feature/tap
L github.com/insomniacslk/dhcp/iana from github.com/insomniacslk/dhcp/dhcpv4
L github.com/insomniacslk/dhcp/interfaces from github.com/insomniacslk/dhcp/dhcpv4
L github.com/insomniacslk/dhcp/rfc1035label from github.com/insomniacslk/dhcp/dhcpv4
@ -302,7 +302,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
gvisor.dev/gvisor/pkg/tcpip/network/internal/fragmentation from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
gvisor.dev/gvisor/pkg/tcpip/network/internal/ip from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
gvisor.dev/gvisor/pkg/tcpip/network/internal/multicast from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
gvisor.dev/gvisor/pkg/tcpip/network/ipv4 from tailscale.com/net/tstun+
gvisor.dev/gvisor/pkg/tcpip/network/ipv4 from tailscale.com/feature/tap+
gvisor.dev/gvisor/pkg/tcpip/network/ipv6 from tailscale.com/wgengine/netstack+
gvisor.dev/gvisor/pkg/tcpip/ports from gvisor.dev/gvisor/pkg/tcpip/stack+
gvisor.dev/gvisor/pkg/tcpip/seqnum from gvisor.dev/gvisor/pkg/tcpip/header+
@ -801,8 +801,9 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
tailscale.com/drive from tailscale.com/client/tailscale+
tailscale.com/envknob from tailscale.com/client/tailscale+
tailscale.com/envknob/featureknob from tailscale.com/client/web+
tailscale.com/feature from tailscale.com/feature/wakeonlan
tailscale.com/feature from tailscale.com/feature/wakeonlan+
tailscale.com/feature/condregister from tailscale.com/tsnet
L tailscale.com/feature/tap from tailscale.com/feature/condregister
tailscale.com/feature/wakeonlan from tailscale.com/feature/condregister
tailscale.com/health from tailscale.com/control/controlclient+
tailscale.com/health/healthmsg from tailscale.com/ipn/ipnlocal

7
cmd/tailscaled/depaware.txt
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@ -112,7 +112,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
github.com/gorilla/securecookie from github.com/gorilla/csrf
github.com/hdevalence/ed25519consensus from tailscale.com/clientupdate/distsign+
L 💣 github.com/illarion/gonotify/v2 from tailscale.com/net/dns
L github.com/insomniacslk/dhcp/dhcpv4 from tailscale.com/net/tstun
L github.com/insomniacslk/dhcp/dhcpv4 from tailscale.com/feature/tap
L github.com/insomniacslk/dhcp/iana from github.com/insomniacslk/dhcp/dhcpv4
L github.com/insomniacslk/dhcp/interfaces from github.com/insomniacslk/dhcp/dhcpv4
L github.com/insomniacslk/dhcp/rfc1035label from github.com/insomniacslk/dhcp/dhcpv4
@ -214,7 +214,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
gvisor.dev/gvisor/pkg/tcpip/network/internal/fragmentation from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
gvisor.dev/gvisor/pkg/tcpip/network/internal/ip from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
gvisor.dev/gvisor/pkg/tcpip/network/internal/multicast from gvisor.dev/gvisor/pkg/tcpip/network/ipv4+
gvisor.dev/gvisor/pkg/tcpip/network/ipv4 from tailscale.com/net/tstun+
gvisor.dev/gvisor/pkg/tcpip/network/ipv4 from tailscale.com/feature/tap+
gvisor.dev/gvisor/pkg/tcpip/network/ipv6 from tailscale.com/wgengine/netstack+
gvisor.dev/gvisor/pkg/tcpip/ports from gvisor.dev/gvisor/pkg/tcpip/stack+
gvisor.dev/gvisor/pkg/tcpip/seqnum from gvisor.dev/gvisor/pkg/tcpip/header+
@ -259,8 +259,9 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
tailscale.com/drive/driveimpl/shared from tailscale.com/drive/driveimpl+
tailscale.com/envknob from tailscale.com/client/tailscale+
tailscale.com/envknob/featureknob from tailscale.com/client/web+
tailscale.com/feature from tailscale.com/feature/wakeonlan
tailscale.com/feature from tailscale.com/feature/wakeonlan+
tailscale.com/feature/condregister from tailscale.com/cmd/tailscaled
L tailscale.com/feature/tap from tailscale.com/feature/condregister
tailscale.com/feature/wakeonlan from tailscale.com/feature/condregister
tailscale.com/health from tailscale.com/control/controlclient+
tailscale.com/health/healthmsg from tailscale.com/ipn/ipnlocal

8
feature/condregister/maybe_tap.go Normal file
View File

@ -0,0 +1,8 @@
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build linux && !ts_omit_tap
package condregister
import _ "tailscale.com/feature/tap"

39
feature/feature.go
View File

@ -4,6 +4,8 @@
// Package feature tracks which features are linked into the binary.
package feature
import "reflect"
var in = map[string]bool{}
// Register notes that the named feature is linked into the binary.
@ -13,3 +15,40 @@ func Register(name string) {
}
in[name] = true
}
// Hook is a func that can only be set once.
//
// It is not safe for concurrent use.
type Hook[Func any] struct {
f Func
ok bool
}
// IsSet reports whether the hook has been set.
func (h *Hook[Func]) IsSet() bool {
return h.ok
}
// Set sets the hook function, panicking if it's already been set
// or f is the zero value.
//
// It's meant to be called in init.
func (h *Hook[Func]) Set(f Func) {
if h.ok {
panic("Set on already-set feature hook")
}
if reflect.ValueOf(f).IsZero() {
panic("Set with zero value")
}
h.f = f
h.ok = true
}
// Get returns the hook function, or panics if it hasn't been set.
// Use IsSet to check if it's been set.
func (h *Hook[Func]) Get() Func {
if !h.ok {
panic("Get on unset feature hook, without IsSet")
}
return h.f
}

24
net/tstun/tap_linux.go → feature/tap/tap_linux.go
View File

@ -1,9 +1,8 @@
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build !ts_omit_tap
package tstun
// Package tap registers Tailscale's experimental (demo) Linux TAP (Layer 2) support.
package tap
import (
"bytes"
@ -26,6 +25,7 @@ import (
"tailscale.com/net/netaddr"
"tailscale.com/net/packet"
"tailscale.com/net/tsaddr"
"tailscale.com/net/tstun"
"tailscale.com/syncs"
"tailscale.com/types/ipproto"
"tailscale.com/types/logger"
@ -38,7 +38,11 @@ import (
// For now just hard code it.
var ourMAC = net.HardwareAddr{0x30, 0x2D, 0x66, 0xEC, 0x7A, 0x93}
func init() { createTAP = createTAPLinux }
const tapDebug = tstun.TAPDebug
func init() {
tstun.CreateTAP.Set(createTAPLinux)
}
func createTAPLinux(logf logger.Logf, tapName, bridgeName string) (tun.Device, error) {
fd, err := unix.Open("/dev/net/tun", unix.O_RDWR, 0)
@ -87,7 +91,10 @@ var (
etherTypeIPv6 = etherType{0x86, 0xDD}
)
const ipv4HeaderLen = 20
const (
ipv4HeaderLen = 20
ethernetFrameSize = 14 // 2 six byte MACs, 2 bytes ethertype
)
const (
consumePacket = true
@ -186,6 +193,11 @@ var (
cgnatNetMask = net.IPMask(net.ParseIP("255.192.0.0").To4())
)
// parsedPacketPool holds a pool of Parsed structs for use in filtering.
// This is needed because escape analysis cannot see that parsed packets
// do not escape through {Pre,Post}Filter{In,Out}.
var parsedPacketPool = sync.Pool{New: func() any { return new(packet.Parsed) }}
// handleDHCPRequest handles receiving a raw TAP ethernet frame and reports whether
// it's been handled as a DHCP request. That is, it reports whether the frame should
// be ignored by the caller and not passed on.
@ -392,7 +404,7 @@ type tapDevice struct {
destMACAtomic syncs.AtomicValue[[6]byte]
}
var _ setIPer = (*tapDevice)(nil)
var _ tstun.SetIPer = (*tapDevice)(nil)
func (t *tapDevice) SetIP(ipV4, ipV6TODO netip.Addr) error {
t.clientIPv4.Store(ipV4.String())

9
net/tstun/tun.go
View File

@ -14,11 +14,12 @@ import (
"time"
"github.com/tailscale/wireguard-go/tun"
"tailscale.com/feature"
"tailscale.com/types/logger"
)
// createTAP is non-nil on Linux.
var createTAP func(logf logger.Logf, tapName, bridgeName string) (tun.Device, error)
// CrateTAP is the hook set by feature/tap.
var CreateTAP feature.Hook[func(logf logger.Logf, tapName, bridgeName string) (tun.Device, error)]
// New returns a tun.Device for the requested device name, along with
// the OS-dependent name that was allocated to the device.
@ -29,7 +30,7 @@ func New(logf logger.Logf, tunName string) (tun.Device, string, error) {
if runtime.GOOS != "linux" {
return nil, "", errors.New("tap only works on Linux")
}
if createTAP == nil { // if the ts_omit_tap tag is used
if !CreateTAP.IsSet() { // if the ts_omit_tap tag is used
return nil, "", errors.New("tap is not supported in this build")
}
f := strings.Split(tunName, ":")
@ -42,7 +43,7 @@ func New(logf logger.Logf, tunName string) (tun.Device, string, error) {
default:
return nil, "", errors.New("bogus tap argument")
}
dev, err = createTAP(logf, tapName, bridgeName)
dev, err = CreateTAP.Get()(logf, tapName, bridgeName)
} else {
dev, err = tun.CreateTUN(tunName, int(DefaultTUNMTU()))
}

11
net/tstun/wrap.go
View File

@ -53,7 +53,8 @@ const PacketStartOffset = device.MessageTransportHeaderSize
// of a packet that can be injected into a tstun.Wrapper.
const MaxPacketSize = device.MaxContentSize
const tapDebug = false // for super verbose TAP debugging
// TAPDebug is whether super verbose TAP debugging is enabled.
const TAPDebug = false
var (
// ErrClosed is returned when attempting an operation on a closed Wrapper.
@ -459,7 +460,7 @@ func (t *Wrapper) pollVector() {
return
}
n, err = reader(t.vectorBuffer[:], sizes, readOffset)
if t.isTAP && tapDebug {
if t.isTAP && TAPDebug {
s := fmt.Sprintf("% x", t.vectorBuffer[0][:])
for strings.HasSuffix(s, " 00") {
s = strings.TrimSuffix(s, " 00")
@ -792,7 +793,9 @@ func (pc *peerConfigTable) outboundPacketIsJailed(p *packet.Parsed) bool {
return c.jailed
}
type setIPer interface {
// SetIPer is the interface expected to be implemented by the TAP implementation
// of tun.Device.
type SetIPer interface {
// SetIP sets the IP addresses of the TAP device.
SetIP(ipV4, ipV6 netip.Addr) error
}
@ -800,7 +803,7 @@ type setIPer interface {
// SetWGConfig is called when a new NetworkMap is received.
func (t *Wrapper) SetWGConfig(wcfg *wgcfg.Config) {
if t.isTAP {
if sip, ok := t.tdev.(setIPer); ok {
if sip, ok := t.tdev.(SetIPer); ok {
sip.SetIP(findV4(wcfg.Addresses), findV6(wcfg.Addresses))
}
}