ipn,cmd/tailscale: implement resigning nodes on tka key removal

Signed-off-by: Tom DNetto <tom@tailscale.com>
2023-03-01 12:47:29 -08:00
parent 3f8e8b04fd
commit e2d652ec4d
5 changed files with 332 additions and 4 deletions
@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"fmt"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -877,3 +878,135 @@ func TestTKAForceDisable(t *testing.T) {
 		t.Fatal("tka was re-initalized")
 	}
 }
+
+func TestTKAAffectedSigs(t *testing.T) {
+	nodePriv := key.NewNode()
+	// toSign := key.NewNode()
+	nlPriv := key.NewNLPrivate()
+
+	pm := must.Get(newProfileManager(new(mem.Store), t.Logf))
+	must.Do(pm.SetPrefs((&ipn.Prefs{
+		Persist: &persist.Persist{
+			PrivateNodeKey: nodePriv,
+			NetworkLockKey: nlPriv,
+		},
+	}).View()))
+
+	// Make a fake TKA authority, to seed local state.
+	disablementSecret := bytes.Repeat([]byte{0xa5}, 32)
+	tkaKey := tka.Key{Kind: tka.Key25519, Public: nlPriv.Public().Verifier(), Votes: 2}
+
+	temp := t.TempDir()
+	tkaPath := filepath.Join(temp, "tka-profile", string(pm.CurrentProfile().ID))
+	os.Mkdir(tkaPath, 0755)
+	chonk, err := tka.ChonkDir(tkaPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	authority, _, err := tka.Create(chonk, tka.State{
+		Keys:               []tka.Key{tkaKey},
+		DisablementSecrets: [][]byte{tka.DisablementKDF(disablementSecret)},
+	}, nlPriv)
+	if err != nil {
+		t.Fatalf("tka.Create() failed: %v", err)
+	}
+
+	untrustedKey := key.NewNLPrivate()
+	tcs := []struct {
+		name    string
+		makeSig func() *tka.NodeKeySignature
+		wantErr string
+	}{
+		{
+			"no error",
+			func() *tka.NodeKeySignature {
+				sig, _ := signNodeKey(tailcfg.TKASignInfo{NodePublic: nodePriv.Public()}, nlPriv)
+				return sig
+			},
+			"",
+		},
+		{
+			"signature for different keyID",
+			func() *tka.NodeKeySignature {
+				sig, _ := signNodeKey(tailcfg.TKASignInfo{NodePublic: nodePriv.Public()}, untrustedKey)
+				return sig
+			},
+			fmt.Sprintf("got signature with keyID %X from request for %X", untrustedKey.KeyID(), nlPriv.KeyID()),
+		},
+		{
+			"invalid signature",
+			func() *tka.NodeKeySignature {
+				sig, _ := signNodeKey(tailcfg.TKASignInfo{NodePublic: nodePriv.Public()}, nlPriv)
+				copy(sig.Signature, []byte{1, 2, 3, 4, 5, 6}) // overwrite with trash to invalid signature
+				return sig
+			},
+			"signature 0 is not valid: invalid signature",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			s := tc.makeSig()
+			ts, client := fakeNoiseServer(t, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				defer r.Body.Close()
+				switch r.URL.Path {
+				case "/machine/tka/affected-sigs":
+					body := new(tailcfg.TKASignaturesUsingKeyRequest)
+					if err := json.NewDecoder(r.Body).Decode(body); err != nil {
+						t.Fatal(err)
+					}
+					if body.Version != tailcfg.CurrentCapabilityVersion {
+						t.Errorf("sign CapVer = %v, want %v", body.Version, tailcfg.CurrentCapabilityVersion)
+					}
+					if body.NodeKey != nodePriv.Public() {
+						t.Errorf("nodeKey = %v, want %v", body.NodeKey, nodePriv.Public())
+					}
+
+					w.WriteHeader(200)
+					if err := json.NewEncoder(w).Encode(tailcfg.TKASignaturesUsingKeyResponse{
+						Signatures: []tkatype.MarshaledSignature{s.Serialize()},
+					}); err != nil {
+						t.Fatal(err)
+					}
+
+				default:
+					t.Errorf("unhandled endpoint path: %v", r.URL.Path)
+					w.WriteHeader(404)
+				}
+			}))
+			defer ts.Close()
+			cc := fakeControlClient(t, client)
+			b := LocalBackend{
+				varRoot: temp,
+				cc:      cc,
+				ccAuto:  cc,
+				logf:    t.Logf,
+				tka: &tkaState{
+					authority: authority,
+					storage:   chonk,
+				},
+				pm:    pm,
+				store: pm.Store(),
+			}
+
+			sigs, err := b.NetworkLockAffectedSigs(nlPriv.KeyID())
+			switch {
+			case tc.wantErr == "" && err != nil:
+				t.Errorf("NetworkLockAffectedSigs() failed: %v", err)
+			case tc.wantErr != "" && err == nil:
+				t.Errorf("NetworkLockAffectedSigs().err = nil, want %q", tc.wantErr)
+			case tc.wantErr != "" && err.Error() != tc.wantErr:
+				t.Errorf("NetworkLockAffectedSigs().err = %q, want %q", err.Error(), tc.wantErr)
+			}
+
+			if tc.wantErr == "" {
+				if len(sigs) != 1 {
+					t.Fatalf("len(sigs) = %d, want 1", len(sigs))
+				}
+				if !bytes.Equal(s.Serialize(), sigs[0]) {
+					t.Errorf("unexpected signature: got %v, want %v", sigs[0], s.Serialize())
+				}
+			}
+		})
+	}
+}