mesh-controller/internal/inventory/secrets_test.go

package inventory

import (
	"context"
	"crypto/ecdh"
	"crypto/rand"
	"encoding/base64"
	"strings"
	"testing"

	"golang.org/x/crypto/nacl/box"
)

// aSealingKey is a node's key, keeping the private half so a test can open what was sealed — the
// only assertion that actually distinguishes "the right blob" from "a blob".
func aSealingKey(t *testing.T) (string, func(string) ([]byte, bool)) {
	t.Helper()
	k, err := ecdh.X25519().GenerateKey(rand.Reader)
	if err != nil {
		t.Fatal(err)
	}
	var pub, priv [32]byte
	copy(pub[:], k.PublicKey().Bytes())
	copy(priv[:], k.Bytes())
	return base64.StdEncoding.EncodeToString(k.PublicKey().Bytes()),
		func(sealed string) ([]byte, bool) {
			blob, err := base64.StdEncoding.DecodeString(sealed)
			if err != nil {
				return nil, false
			}
			return box.OpenAnonymous(nil, blob, &pub, &priv)
		}
}

func twoNodesWithKeys(t *testing.T) (*Inventory, context.Context) {
	t.Helper()
	inv := fresh(t)
	ctx := context.Background()
	for _, n := range []string{"consumer", "provider"} {
		node, err := inv.AddNode(ctx, n)
		if err != nil {
			t.Fatal(err)
		}
		key, _ := aSealingKey(t)
		if err := inv.RecordSealingKey(ctx, node.ID, key); err != nil {
			t.Fatal(err)
		}
	}
	return inv, ctx
}

func TestASecretIsMadeOnceAndKept(t *testing.T) {
	// Regenerating on every declaration would restart both ends on every push, and — worse — the
	// password a provider was told to create would never be the one its consumer was given.
	inv, ctx := twoNodesWithKeys(t)
	first, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	second, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	if first.ForConsumer != second.ForConsumer || first.ForProvider != second.ForProvider {
		t.Fatal("asking twice produced two different credentials")
	}
}

func TestTheStoredSecretIsNotTheSecret(t *testing.T) {
	// The whole point. A copy of this database is not a copy of the mesh's credentials — which is
	// what an encrypted column does not achieve, because whoever runs the control plane can read
	// through it.
	inv, ctx := twoNodesWithKeys(t)
	got, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	var columns []string
	rows, err := inv.store.Pool().Query(ctx,
		`select column_name from information_schema.columns where table_name = 'secret'`)
	if err != nil {
		t.Fatal(err)
	}
	defer rows.Close()
	for rows.Next() {
		var c string
		if err := rows.Scan(&c); err != nil {
			t.Fatal(err)
		}
		columns = append(columns, c)
	}
	for _, c := range columns {
		if strings.Contains(c, "password") || strings.Contains(c, "value") ||
			strings.Contains(c, "plain") {
			t.Fatalf("the table has a column called %q, which suggests it holds the thing", c)
		}
	}
	if got.ForConsumer == got.ForProvider {
		t.Fatal("both ends were given the identical blob, so the storage reveals they match")
	}
}

func TestANewSealingKeyMeansANewSecret(t *testing.T) {
	// A node that rejoined generated a new key and can no longer open what was sealed to the old
	// one. Keeping the blob would deliver something unreadable for ever, reported as configured.
	inv, ctx := twoNodesWithKeys(t)
	before, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	node, err := inv.NodeByName(ctx, "consumer")
	if err != nil {
		t.Fatal(err)
	}
	fresh, _ := aSealingKey(t)
	if err := inv.RecordSealingKey(ctx, node.ID, fresh); err != nil {
		t.Fatal(err)
	}
	after, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	if after.ForConsumer == before.ForConsumer {
		t.Fatal("the node was handed a credential sealed to a key it no longer has")
	}
	// And the provider's copy changed too, in the same breath. Otherwise the two ends hold
	// different passwords — which is the fanout window that makes rotation dangerous elsewhere.
	if after.ForProvider == before.ForProvider {
		t.Fatal("only one end was rotated, so the two now disagree")
	}
}

func TestRotatingReachesBothEnds(t *testing.T) {
	inv, ctx := twoNodesWithKeys(t)
	before, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	if err := inv.RotateSecret(ctx, "database", "consumer", "provider"); err != nil {
		t.Fatal(err)
	}
	after, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err != nil {
		t.Fatal(err)
	}
	if after.ForConsumer == before.ForConsumer || after.ForProvider == before.ForProvider {
		t.Fatal("rotation left one of the ends holding what it had")
	}
}

func TestAProviderIsToldEveryCredentialItMustCreate(t *testing.T) {
	// The half that makes a credential real. A password nothing was told to create authenticates
	// nowhere, and the mesh cannot tell the provider what it is in any other way — it cannot read
	// it either.
	inv, ctx := twoNodesWithKeys(t)
	// The provider's own key, kept, so this asserts it can *open* what it was handed rather than
	// that the field is non-empty. Without that, selecting the wrong column reads the same both
	// ways and the test proves nothing — which it did, until the check was removed and it passed.
	providerKey, openProvider := aSealingKey(t)
	provider, err := inv.NodeByName(ctx, "provider")
	if err != nil {
		t.Fatal(err)
	}
	if err := inv.RecordSealingKey(ctx, provider.ID, providerKey); err != nil {
		t.Fatal(err)
	}

	other, err := inv.AddNode(ctx, "second-consumer")
	if err != nil {
		t.Fatal(err)
	}
	secondKey, _ := aSealingKey(t)
	if err := inv.RecordSealingKey(ctx, other.ID, secondKey); err != nil {
		t.Fatal(err)
	}
	for _, who := range []string{"consumer", "second-consumer"} {
		if _, err := inv.SecretFor(ctx, "database", who, "provider"); err != nil {
			t.Fatal(err)
		}
	}
	issued, err := inv.SecretsFrom(ctx, "provider")
	if err != nil {
		t.Fatal(err)
	}
	if len(issued) != 2 {
		t.Fatalf("the provider was told about %d of 2", len(issued))
	}
	for _, s := range issued {
		if _, ok := openProvider(s.ForProvider); !ok {
			t.Fatalf("the provider cannot open the credential it was given for %s", s.Consumer)
		}
		if s.ForConsumer != "" {
			// It has no business holding the other end's copy, and handing it out would put a
			// second readable-by-someone-else copy into circulation.
			t.Fatalf("the provider was handed the consumer's own copy of %s", s.Name)
		}
	}
}

func TestANodeWithNoSealingKeyCannotBeGivenASecret(t *testing.T) {
	inv := fresh(t)
	ctx := context.Background()
	for _, n := range []string{"consumer", "provider"} {
		if _, err := inv.AddNode(ctx, n); err != nil {
			t.Fatal(err)
		}
	}
	_, err := inv.SecretFor(ctx, "database", "consumer", "provider")
	if err == nil {
		t.Fatal("a credential was made for nodes that cannot open one")
	}
	if !strings.Contains(err.Error(), "sealing key") {
		t.Fatalf("the refusal does not say what is missing: %v", err)
	}
}

func TestSecretsGoWhenANodeLeaves(t *testing.T) {
	inv, ctx := twoNodesWithKeys(t)
	if _, err := inv.SecretFor(ctx, "database", "consumer", "provider"); err != nil {
		t.Fatal(err)
	}
	if _, err := inv.store.Pool().Exec(ctx, `delete from node where name = 'consumer'`); err != nil {
		t.Fatal(err)
	}
	var left int
	if err := inv.store.Pool().QueryRow(ctx, `select count(*) from secret`).Scan(&left); err != nil {
		t.Fatal(err)
	}
	if left != 0 {
		t.Fatalf("%d credential(s) outlived the machine they were for", left)
	}
}