mirror of
https://github.com/tailscale/tailscale.git
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401 lines
12 KiB
Go
401 lines
12 KiB
Go
// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package ipnlocal
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import (
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"bytes"
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"net/http"
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"os"
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"path/filepath"
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"time"
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"tailscale.com/envknob"
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"tailscale.com/ipn/ipnstate"
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"tailscale.com/logtail/backoff"
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"tailscale.com/tailcfg"
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"tailscale.com/tka"
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"tailscale.com/types/key"
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"tailscale.com/types/netmap"
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"tailscale.com/types/tkatype"
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)
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var networkLockAvailable = envknob.RegisterBool("TS_EXPERIMENTAL_NETWORK_LOCK")
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type tkaState struct {
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authority *tka.Authority
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storage *tka.FS
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}
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// tkaSyncIfNeededLocked examines TKA info reported from the control plane,
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// performing the steps necessary to synchronize local tka state.
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//
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// There are 4 scenarios handled here:
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// - Enablement: nm.TKAEnabled but b.tka == nil
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// ∴ reach out to /machine/tka/boostrap to get the genesis AUM, then
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// initialize TKA.
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// - Disablement: !nm.TKAEnabled but b.tka != nil
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// ∴ reach out to /machine/tka/boostrap to read the disablement secret,
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// then verify and clear tka local state.
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// - Sync needed: b.tka.Head != nm.TKAHead
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// ∴ complete multi-step synchronization flow.
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// - Everything up to date: All other cases.
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// ∴ no action necessary.
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//
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// b.mu must be held. b.mu will be stepped out of (and back in) during network
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// RPCs.
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func (b *LocalBackend) tkaSyncIfNeededLocked(nm *netmap.NetworkMap) error {
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if !networkLockAvailable() {
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// If the feature flag is not enabled, pretend we don't exist.
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return nil
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}
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if nm.SelfNode == nil {
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return errors.New("SelfNode missing")
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}
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isEnabled := b.tka != nil
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wantEnabled := nm.TKAEnabled
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if isEnabled != wantEnabled {
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var ourHead tka.AUMHash
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if b.tka != nil {
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ourHead = b.tka.authority.Head()
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}
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// Regardless of whether we are moving to disabled or enabled, we
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// need information from the tka bootstrap endpoint.
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b.mu.Unlock()
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bs, err := b.tkaFetchBootstrap(nm.SelfNode.ID, ourHead)
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b.mu.Lock()
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if err != nil {
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return fmt.Errorf("fetching bootstrap: %v", err)
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}
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if wantEnabled && !isEnabled {
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if err := b.tkaBootstrapFromGenesisLocked(bs.GenesisAUM); err != nil {
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return fmt.Errorf("bootstrap: %v", err)
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}
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isEnabled = true
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} else if !wantEnabled && isEnabled {
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if b.tka.authority.ValidDisablement(bs.DisablementSecret) {
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b.tka = nil
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isEnabled = false
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if err := os.RemoveAll(b.chonkPath()); err != nil {
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return fmt.Errorf("os.RemoveAll: %v", err)
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}
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} else {
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b.logf("Disablement secret did not verify, leaving TKA enabled.")
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}
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} else {
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return fmt.Errorf("[bug] unreachable invariant of wantEnabled /w isEnabled")
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}
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}
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if isEnabled && b.tka.authority.Head() != nm.TKAHead {
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// TODO(tom): Implement sync
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}
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return nil
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}
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// chonkPath returns the absolute path to the directory in which TKA
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// state (the 'tailchonk') is stored.
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func (b *LocalBackend) chonkPath() string {
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return filepath.Join(b.TailscaleVarRoot(), "tka")
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}
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// tkaBootstrapFromGenesisLocked initializes the local (on-disk) state of the
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// tailnet key authority, based on the given genesis AUM.
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//
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// b.mu must be held.
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func (b *LocalBackend) tkaBootstrapFromGenesisLocked(g tkatype.MarshaledAUM) error {
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if !b.CanSupportNetworkLock() {
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return errors.New("network lock not supported in this configuration")
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}
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var genesis tka.AUM
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if err := genesis.Unserialize(g); err != nil {
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return fmt.Errorf("reading genesis: %v", err)
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}
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chonkDir := b.chonkPath()
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if err := os.Mkdir(chonkDir, 0755); err != nil && !os.IsExist(err) {
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return fmt.Errorf("mkdir: %v", err)
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}
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chonk, err := tka.ChonkDir(chonkDir)
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if err != nil {
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return fmt.Errorf("chonk: %v", err)
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}
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authority, err := tka.Bootstrap(chonk, genesis)
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if err != nil {
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return fmt.Errorf("tka bootstrap: %v", err)
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}
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b.tka = &tkaState{
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authority: authority,
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storage: chonk,
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}
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return nil
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}
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// CanSupportNetworkLock returns true if tailscaled is able to operate
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// a local tailnet key authority (and hence enforce network lock).
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func (b *LocalBackend) CanSupportNetworkLock() bool {
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if b.tka != nil {
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// The TKA is being used, so yeah its supported.
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return true
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}
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if b.TailscaleVarRoot() != "" {
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// Theres a var root (aka --statedir), so if network lock gets
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// initialized we have somewhere to store our AUMs. Thats all
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// we need.
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return true
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}
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return false
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}
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// NetworkLockStatus returns a structure describing the state of the
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// tailnet key authority, if any.
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func (b *LocalBackend) NetworkLockStatus() *ipnstate.NetworkLockStatus {
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if b.tka == nil {
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return &ipnstate.NetworkLockStatus{
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Enabled: false,
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PublicKey: b.nlPrivKey.Public(),
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}
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}
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var head [32]byte
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h := b.tka.authority.Head()
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copy(head[:], h[:])
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return &ipnstate.NetworkLockStatus{
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Enabled: true,
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Head: &head,
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PublicKey: b.nlPrivKey.Public(),
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}
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}
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// NetworkLockInit enables network-lock for the tailnet, with the tailnets'
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// key authority initialized to trust the provided keys.
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//
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// Initialization involves two RPCs with control, termed 'begin' and 'finish'.
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// The Begin RPC transmits the genesis Authority Update Message, which
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// encodes the initial state of the authority, and the list of all nodes
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// needing signatures is returned as a response.
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// The Finish RPC submits signatures for all these nodes, at which point
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// Control has everything it needs to atomically enable network lock.
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func (b *LocalBackend) NetworkLockInit(keys []tka.Key) error {
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if b.tka != nil {
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return errors.New("network-lock is already initialized")
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}
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if !networkLockAvailable() {
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return errors.New("this is an experimental feature in your version of tailscale - Please upgrade to the latest to use this.")
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}
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if !b.CanSupportNetworkLock() {
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return errors.New("network-lock is not supported in this configuration. Did you supply a --statedir?")
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}
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nm := b.NetMap()
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if nm == nil {
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return errors.New("no netmap: are you logged into tailscale?")
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}
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// Generates a genesis AUM representing trust in the provided keys.
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// We use an in-memory tailchonk because we don't want to commit to
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// the filesystem until we've finished the initialization sequence,
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// just in case something goes wrong.
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_, genesisAUM, err := tka.Create(&tka.Mem{}, tka.State{
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Keys: keys,
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// TODO(tom): Actually plumb a real disablement value.
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DisablementSecrets: [][]byte{bytes.Repeat([]byte{1}, 32)},
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}, b.nlPrivKey)
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if err != nil {
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return fmt.Errorf("tka.Create: %v", err)
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}
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b.logf("Generated genesis AUM to initialize network lock, trusting the following keys:")
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for i, k := range genesisAUM.State.Keys {
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b.logf(" - key[%d] = nlpub:%x with %d votes", i, k.Public, k.Votes)
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}
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// Phase 1/2 of initialization: Transmit the genesis AUM to Control.
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initResp, err := b.tkaInitBegin(nm, genesisAUM)
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if err != nil {
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return fmt.Errorf("tka init-begin RPC: %w", err)
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}
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// Our genesis AUM was accepted but before Control turns on enforcement of
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// node-key signatures, we need to sign keys for all the existing nodes.
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// If we don't get these signatures ahead of time, everyone will loose
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// connectivity because control won't have any signatures to send which
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// satisfy network-lock checks.
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sigs := make(map[tailcfg.NodeID]tkatype.MarshaledSignature, len(initResp.NeedSignatures))
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for _, nodeInfo := range initResp.NeedSignatures {
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nks, err := signNodeKey(nodeInfo, b.nlPrivKey)
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if err != nil {
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return fmt.Errorf("generating signature: %v", err)
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}
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sigs[nodeInfo.NodeID] = nks.Serialize()
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}
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// Finalize enablement by transmitting signature for all nodes to Control.
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_, err = b.tkaInitFinish(nm, sigs)
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return err
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}
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func signNodeKey(nodeInfo tailcfg.TKASignInfo, signer key.NLPrivate) (*tka.NodeKeySignature, error) {
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p, err := nodeInfo.NodePublic.MarshalBinary()
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if err != nil {
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return nil, err
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}
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sig := tka.NodeKeySignature{
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SigKind: tka.SigDirect,
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KeyID: signer.KeyID(),
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Pubkey: p,
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WrappingPubkey: nodeInfo.RotationPubkey,
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}
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sig.Signature, err = signer.SignNKS(sig.SigHash())
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if err != nil {
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return nil, fmt.Errorf("signature failed: %w", err)
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}
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return &sig, nil
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}
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func (b *LocalBackend) tkaInitBegin(nm *netmap.NetworkMap, aum tka.AUM) (*tailcfg.TKAInitBeginResponse, error) {
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var req bytes.Buffer
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if err := json.NewEncoder(&req).Encode(tailcfg.TKAInitBeginRequest{
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NodeID: nm.SelfNode.ID,
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GenesisAUM: aum.Serialize(),
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}); err != nil {
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return nil, fmt.Errorf("encoding request: %v", err)
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}
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ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
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defer cancel()
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bo := backoff.NewBackoff("tka-init-begin", b.logf, 5*time.Second)
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for {
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if err := ctx.Err(); err != nil {
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return nil, fmt.Errorf("ctx: %w", err)
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}
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req, err := http.NewRequestWithContext(ctx, "GET", "https://unused/machine/tka/init/begin", &req)
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if err != nil {
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return nil, fmt.Errorf("req: %w", err)
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}
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res, err := b.DoNoiseRequest(req)
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if err != nil {
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bo.BackOff(ctx, err)
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continue
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}
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if res.StatusCode != 200 {
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body, _ := io.ReadAll(res.Body)
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res.Body.Close()
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return nil, fmt.Errorf("request returned (%d): %s", res.StatusCode, string(body))
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}
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a := new(tailcfg.TKAInitBeginResponse)
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err = json.NewDecoder(res.Body).Decode(a)
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res.Body.Close()
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if err != nil {
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return nil, fmt.Errorf("decoding JSON: %w", err)
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}
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return a, nil
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}
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}
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func (b *LocalBackend) tkaInitFinish(nm *netmap.NetworkMap, nks map[tailcfg.NodeID]tkatype.MarshaledSignature) (*tailcfg.TKAInitFinishResponse, error) {
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var req bytes.Buffer
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if err := json.NewEncoder(&req).Encode(tailcfg.TKAInitFinishRequest{
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NodeID: nm.SelfNode.ID,
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Signatures: nks,
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}); err != nil {
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return nil, fmt.Errorf("encoding request: %v", err)
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}
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ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
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defer cancel()
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bo := backoff.NewBackoff("tka-init-finish", b.logf, 5*time.Second)
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for {
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if err := ctx.Err(); err != nil {
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return nil, fmt.Errorf("ctx: %w", err)
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}
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req, err := http.NewRequestWithContext(ctx, "GET", "https://unused/machine/tka/init/finish", &req)
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if err != nil {
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return nil, fmt.Errorf("req: %w", err)
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}
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res, err := b.DoNoiseRequest(req)
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if err != nil {
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bo.BackOff(ctx, err)
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continue
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}
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if res.StatusCode != 200 {
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body, _ := io.ReadAll(res.Body)
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res.Body.Close()
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return nil, fmt.Errorf("request returned (%d): %s", res.StatusCode, string(body))
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}
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a := new(tailcfg.TKAInitFinishResponse)
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err = json.NewDecoder(res.Body).Decode(a)
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res.Body.Close()
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if err != nil {
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return nil, fmt.Errorf("decoding JSON: %w", err)
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}
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return a, nil
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}
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}
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// tkaFetchBootstrap sends a /machine/tka/bootstrap RPC to the control plane
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// over noise. This is used to get values necessary to enable or disable TKA.
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func (b *LocalBackend) tkaFetchBootstrap(nodeID tailcfg.NodeID, head tka.AUMHash) (*tailcfg.TKABootstrapResponse, error) {
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bootstrapReq := tailcfg.TKABootstrapRequest{
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NodeID: nodeID,
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}
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if !head.IsZero() {
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head, err := head.MarshalText()
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if err != nil {
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return nil, fmt.Errorf("head.MarshalText failed: %v", err)
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}
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bootstrapReq.Head = string(head)
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}
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var req bytes.Buffer
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if err := json.NewEncoder(&req).Encode(bootstrapReq); err != nil {
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return nil, fmt.Errorf("encoding request: %v", err)
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}
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ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
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defer cancel()
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if err := ctx.Err(); err != nil {
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return nil, fmt.Errorf("ctx: %w", err)
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}
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req2, err := http.NewRequestWithContext(ctx, "GET", "https://unused/machine/tka/bootstrap", &req)
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if err != nil {
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return nil, fmt.Errorf("req: %w", err)
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}
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res, err := b.DoNoiseRequest(req2)
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if err != nil {
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return nil, fmt.Errorf("resp: %w", err)
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}
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if res.StatusCode != 200 {
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body, _ := io.ReadAll(res.Body)
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res.Body.Close()
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return nil, fmt.Errorf("request returned (%d): %s", res.StatusCode, string(body))
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}
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a := new(tailcfg.TKABootstrapResponse)
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err = json.NewDecoder(res.Body).Decode(a)
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res.Body.Close()
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if err != nil {
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return nil, fmt.Errorf("decoding JSON: %w", err)
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}
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return a, nil
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}
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