cmd/tailscale,ipn: implement lock log command

This commit implements `tailscale lock log [--limit N]`, which displays an ordered list
of changes to network-lock state in a manner familiar to `git log`.

Signed-off-by: Tom DNetto <tom@tailscale.com>

client/tailscale/localclient.go

@@ -829,6 +829,17 @@ func (lc *LocalClient) NetworkLockSign(ctx context.Context, nodeKey key.NodePubl
 	return nil
 }
 
+// NetworkLockLog returns up to maxEntries number of changes to network-lock state.
+func (lc *LocalClient) NetworkLockLog(ctx context.Context, maxEntries int) ([]ipnstate.NetworkLockUpdate, error) {
+	v := url.Values{}
+	v.Set("limit", fmt.Sprint(maxEntries))
+	body, err := lc.send(ctx, "GET", "/localapi/v0/tka/log?"+v.Encode(), 200, nil)
+	if err != nil {
+		return nil, fmt.Errorf("error %w: %s", err, body)
+	}
+	return decodeJSON[[]ipnstate.NetworkLockUpdate](body)
+}
+
 // SetServeConfig sets or replaces the serving settings.
 // If config is nil, settings are cleared and serving is disabled.
 func (lc *LocalClient) SetServeConfig(ctx context.Context, config *ipn.ServeConfig) error {

cmd/tailscale/cli/network-lock.go

@@ -7,12 +7,18 @@ package cli
 import (
 	"context"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
+	"flag"
 	"fmt"
+	"os"
 	"strconv"
 	"strings"
 
+	"github.com/mattn/go-colorable"
+	"github.com/mattn/go-isatty"
 	"github.com/peterbourgon/ff/v3/ffcli"
+	"tailscale.com/ipn/ipnstate"
 	"tailscale.com/tka"
 	"tailscale.com/types/key"
 )
@@ -29,6 +35,7 @@ var netlockCmd = &ffcli.Command{
 		nlSignCmd,
 		nlDisableCmd,
 		nlDisablementKDFCmd,
+		nlLogCmd,
 	},
 	Exec: runNetworkLockStatus,
 }
@@ -282,3 +289,100 @@ func runNetworkLockDisablementKDF(ctx context.Context, args []string) error {
 	fmt.Printf("disablement:%x\n", tka.DisablementKDF(secret))
 	return nil
 }
+
+var nlLogArgs struct {
+	limit int
+}
+
+var nlLogCmd = &ffcli.Command{
+	Name:       "log",
+	ShortUsage: "log [--limit N]",
+	ShortHelp:  "List changes applied to network-lock",
+	Exec:       runNetworkLockLog,
+	FlagSet: (func() *flag.FlagSet {
+		fs := newFlagSet("lock log")
+		fs.IntVar(&nlLogArgs.limit, "limit", 50, "max number of updates to list")
+		return fs
+	})(),
+}
+
+func nlDescribeUpdate(update ipnstate.NetworkLockUpdate, color bool) (string, error) {
+	terminalYellow := ""
+	terminalClear := ""
+	if color {
+		terminalYellow = "\x1b[33m"
+		terminalClear = "\x1b[0m"
+	}
+
+	var stanza strings.Builder
+	printKey := func(key *tka.Key, prefix string) {
+		fmt.Fprintf(&stanza, "%sType: %s\n", prefix, key.Kind.String())
+		fmt.Fprintf(&stanza, "%sKeyID: %x\n", prefix, key.ID())
+		fmt.Fprintf(&stanza, "%sVotes: %d\n", prefix, key.Votes)
+		if key.Meta != nil {
+			fmt.Fprintf(&stanza, "%sMetadata: %+v\n", prefix, key.Meta)
+		}
+	}
+
+	var aum tka.AUM
+	if err := aum.Unserialize(update.Raw); err != nil {
+		return "", fmt.Errorf("decoding: %w", err)
+	}
+
+	fmt.Fprintf(&stanza, "%supdate %x (%s)%s\n", terminalYellow, update.Hash, update.Change, terminalClear)
+
+	switch update.Change {
+	case tka.AUMAddKey.String():
+		printKey(aum.Key, "")
+	case tka.AUMRemoveKey.String():
+		fmt.Fprintf(&stanza, "KeyID: %x\n", aum.KeyID)
+
+	case tka.AUMUpdateKey.String():
+		fmt.Fprintf(&stanza, "KeyID: %x\n", aum.KeyID)
+		if aum.Votes != nil {
+			fmt.Fprintf(&stanza, "Votes: %d\n", aum.Votes)
+		}
+		if aum.Meta != nil {
+			fmt.Fprintf(&stanza, "Metadata: %+v\n", aum.Meta)
+		}
+
+	case tka.AUMCheckpoint.String():
+		fmt.Fprintln(&stanza, "Disablement values:")
+		for _, v := range aum.State.DisablementSecrets {
+			fmt.Fprintf(&stanza, " - %x\n", v)
+		}
+		fmt.Fprintln(&stanza, "Keys:")
+		for _, k := range aum.State.Keys {
+			printKey(&k, "  ")
+		}
+
+	default:
+		// Print a JSON encoding of the AUM as a fallback.
+		e := json.NewEncoder(&stanza)
+		e.SetIndent("", "\t")
+		if err := e.Encode(aum); err != nil {
+			return "", err
+		}
+		stanza.WriteRune('\n')
+	}
+
+	return stanza.String(), nil
+}
+
+func runNetworkLockLog(ctx context.Context, args []string) error {
+	updates, err := localClient.NetworkLockLog(ctx, nlLogArgs.limit)
+	if err != nil {
+		return fixTailscaledConnectError(err)
+	}
+	useColor := isatty.IsTerminal(os.Stdout.Fd())
+
+	stdOut := colorable.NewColorableStdout()
+	for _, update := range updates {
+		stanza, err := nlDescribeUpdate(update, useColor)
+		if err != nil {
+			return err
+		}
+		fmt.Fprintln(stdOut, stanza)
+	}
+	return nil
+}

cmd/tailscale/depaware.txt

@@ -14,6 +14,8 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
    L    github.com/jsimonetti/rtnetlink/internal/unix                from github.com/jsimonetti/rtnetlink
         github.com/kballard/go-shellquote                            from tailscale.com/cmd/tailscale/cli
         github.com/klauspost/compress/flate                          from nhooyr.io/websocket
+     💣 github.com/mattn/go-colorable                                from tailscale.com/cmd/tailscale/cli
+     💣 github.com/mattn/go-isatty                                   from github.com/mattn/go-colorable+
    L 💣 github.com/mdlayher/netlink                                  from github.com/jsimonetti/rtnetlink+
    L 💣 github.com/mdlayher/netlink/nlenc                            from github.com/jsimonetti/rtnetlink+
    L 💣 github.com/mdlayher/socket                                   from github.com/mdlayher/netlink

go.mod

@@ -36,6 +36,8 @@ require (
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51
 	github.com/klauspost/compress v1.15.4
 	github.com/kortschak/wol v0.0.0-20200729010619-da482cc4850a
+	github.com/mattn/go-colorable v0.1.12
+	github.com/mattn/go-isatty v0.0.14
 	github.com/mdlayher/genetlink v1.2.0
 	github.com/mdlayher/netlink v1.6.0
 	github.com/mdlayher/sdnotify v1.0.0
@@ -199,8 +201,6 @@ require (
 	github.com/magiconair/properties v1.8.5 // indirect
 	github.com/maratori/testpackage v1.0.1 // indirect
 	github.com/matoous/godox v0.0.0-20210227103229-6504466cf951 // indirect
-	github.com/mattn/go-colorable v0.1.12 // indirect
-	github.com/mattn/go-isatty v0.0.14 // indirect
 	github.com/mattn/go-runewidth v0.0.13 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
 	github.com/mbilski/exhaustivestruct v1.2.0 // indirect

ipn/ipnlocal/network-lock.go

@@ -647,6 +647,43 @@ func (b *LocalBackend) NetworkLockDisable(secret []byte) error {
 	return err
 }
 
+// NetworkLockLog returns the changelog of TKA state up to maxEntries in size.
+func (b *LocalBackend) NetworkLockLog(maxEntries int) ([]ipnstate.NetworkLockUpdate, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.tka == nil {
+		return nil, errNetworkLockNotActive
+	}
+
+	var out []ipnstate.NetworkLockUpdate
+	cursor := b.tka.authority.Head()
+	for i := 0; i < maxEntries; i++ {
+		aum, err := b.tka.storage.AUM(cursor)
+		if err != nil {
+			if err == os.ErrNotExist {
+				break
+			}
+			return out, fmt.Errorf("reading AUM: %w", err)
+		}
+
+		update := ipnstate.NetworkLockUpdate{
+			Hash:   cursor,
+			Change: aum.MessageKind.String(),
+			Raw:    aum.Serialize(),
+		}
+		out = append(out, update)
+
+		parent, hasParent := aum.Parent()
+		if !hasParent {
+			break
+		}
+		cursor = parent
+	}
+
+	return out, nil
+}
+
 func signNodeKey(nodeInfo tailcfg.TKASignInfo, signer key.NLPrivate) (*tka.NodeKeySignature, error) {
 	p, err := nodeInfo.NodePublic.MarshalBinary()
 	if err != nil {

ipn/ipnstate/ipnstate.go

@@ -101,6 +101,16 @@ type NetworkLockStatus struct {
 	TrustedKeys []TKAKey
 }
 
+// NetworkLockUpdate describes a change to network-lock state.
+type NetworkLockUpdate struct {
+	Hash   [32]byte
+	Change string // values of tka.AUMKind.String()
+
+	// Raw contains the serialized AUM. The AUM is sent in serialized
+	// form to avoid transitive dependences bloating this package.
+	Raw []byte
+}
+
 // TailnetStatus is information about a Tailscale network ("tailnet").
 type TailnetStatus struct {
 	// Name is the name of the network that's currently in use.

ipn/localapi/localapi.go

@@ -82,6 +82,7 @@ var handler = map[string]localAPIHandler{
 	"set-expiry-sooner":       (*Handler).serveSetExpirySooner,
 	"status":                  (*Handler).serveStatus,
 	"tka/init":                (*Handler).serveTKAInit,
+	"tka/log":                 (*Handler).serveTKALog,
 	"tka/modify":              (*Handler).serveTKAModify,
 	"tka/sign":                (*Handler).serveTKASign,
 	"tka/status":              (*Handler).serveTKAStatus,
@@ -1164,6 +1165,37 @@ func (h *Handler) serveTKADisable(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(200)
 }
 
+func (h *Handler) serveTKALog(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "use GET", http.StatusMethodNotAllowed)
+		return
+	}
+
+	limit := 50
+	if limitStr := r.FormValue("limit"); limitStr != "" {
+		l, err := strconv.Atoi(limitStr)
+		if err != nil {
+			http.Error(w, "parsing 'limit' parameter: "+err.Error(), http.StatusBadRequest)
+			return
+		}
+		limit = int(l)
+	}
+
+	updates, err := h.b.NetworkLockLog(limit)
+	if err != nil {
+		http.Error(w, "reading log failed: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	j, err := json.MarshalIndent(updates, "", "\t")
+	if err != nil {
+		http.Error(w, "JSON encoding error", 500)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.Write(j)
+}
+
 // serveProfiles serves profile switching-related endpoints. Supported methods
 // and paths are:
 //   - GET /profiles/: list all profiles (JSON-encoded array of ipn.LoginProfiles)