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hscontrol/state: allow expired auth keys for node re-registration
Skip auth key validation for existing nodes re-registering with the same NodeKey. Pre-auth keys are only required for initial authentication. NodeKey rotation still requires a valid auth key as it is a security-sensitive operation that changes the node's cryptographic identity. Fixes #2830
This commit is contained in:
Kristoffer Dalby
committed by
Kristoffer Dalby
Kristoffer Dalby
parent
abed534628
commit
4728a2ba9e
@@ -3004,3 +3004,296 @@ func createTestApp(t *testing.T) *Headscale {
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return app
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}
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// TestGitHubIssue2830_NodeRestartWithUsedPreAuthKey tests the scenario reported in
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// https://github.com/juanfont/headscale/issues/2830
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//
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// Scenario:
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// 1. Node registers successfully with a single-use pre-auth key
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// 2. Node is running fine
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// 3. Node restarts (e.g., after headscale upgrade or tailscale container restart)
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// 4. Node sends RegisterRequest with the same pre-auth key
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// 5. BUG: Headscale rejects the request with "authkey expired" or "authkey already used"
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//
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// Expected behavior:
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// When an existing node (identified by matching NodeKey + MachineKey) re-registers
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// with a pre-auth key that it previously used, the registration should succeed.
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// The node is not creating a new registration - it's re-authenticating the same device.
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func TestGitHubIssue2830_NodeRestartWithUsedPreAuthKey(t *testing.T) {
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t.Parallel()
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app := createTestApp(t)
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// Create user and single-use pre-auth key
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user := app.state.CreateUserForTest("test-user")
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pak, err := app.state.CreatePreAuthKey(types.UserID(user.ID), false, false, nil, nil) // reusable=false
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require.NoError(t, err)
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require.False(t, pak.Reusable, "key should be single-use for this test")
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machineKey := key.NewMachine()
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nodeKey := key.NewNode()
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// STEP 1: Initial registration with pre-auth key (simulates fresh node joining)
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initialReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: pak.Key,
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},
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NodeKey: nodeKey.Public(),
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "test-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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t.Log("Step 1: Initial registration with pre-auth key")
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initialResp, err := app.handleRegister(context.Background(), initialReq, machineKey.Public())
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require.NoError(t, err, "initial registration should succeed")
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require.NotNil(t, initialResp)
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assert.True(t, initialResp.MachineAuthorized, "node should be authorized")
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assert.False(t, initialResp.NodeKeyExpired, "node key should not be expired")
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// Verify node was created in database
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node, found := app.state.GetNodeByNodeKey(nodeKey.Public())
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require.True(t, found, "node should exist after initial registration")
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assert.Equal(t, "test-node", node.Hostname())
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assert.Equal(t, nodeKey.Public(), node.NodeKey())
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assert.Equal(t, machineKey.Public(), node.MachineKey())
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// Verify pre-auth key is now marked as used
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usedPak, err := app.state.GetPreAuthKey(pak.Key)
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require.NoError(t, err)
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assert.True(t, usedPak.Used, "pre-auth key should be marked as used after initial registration")
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// STEP 2: Simulate node restart - node sends RegisterRequest again with same pre-auth key
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// This happens when:
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// - Tailscale container restarts
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// - Tailscaled service restarts
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// - System reboots
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// The Tailscale client persists the pre-auth key in its state and sends it on every registration
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t.Log("Step 2: Node restart - re-registration with same (now used) pre-auth key")
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restartReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: pak.Key, // Same key, now marked as Used=true
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},
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NodeKey: nodeKey.Public(), // Same node key
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "test-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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// BUG: This fails with "authkey already used" or "authkey expired"
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// EXPECTED: Should succeed because it's the same node re-registering
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restartResp, err := app.handleRegister(context.Background(), restartReq, machineKey.Public())
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// This is the assertion that currently FAILS in v0.27.0
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assert.NoError(t, err, "BUG: existing node re-registration with its own used pre-auth key should succeed")
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if err != nil {
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t.Logf("Error received (this is the bug): %v", err)
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t.Logf("Expected behavior: Node should be able to re-register with the same pre-auth key it used initially")
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return // Stop here to show the bug clearly
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}
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require.NotNil(t, restartResp)
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assert.True(t, restartResp.MachineAuthorized, "node should remain authorized after restart")
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assert.False(t, restartResp.NodeKeyExpired, "node key should not be expired after restart")
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// Verify it's the same node (not a duplicate)
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nodeAfterRestart, found := app.state.GetNodeByNodeKey(nodeKey.Public())
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require.True(t, found, "node should still exist after restart")
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assert.Equal(t, node.ID(), nodeAfterRestart.ID(), "should be the same node, not a new one")
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assert.Equal(t, "test-node", nodeAfterRestart.Hostname())
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}
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// TestNodeReregistrationWithReusablePreAuthKey tests that reusable keys work correctly
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// for node re-registration.
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func TestNodeReregistrationWithReusablePreAuthKey(t *testing.T) {
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t.Parallel()
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app := createTestApp(t)
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user := app.state.CreateUserForTest("test-user")
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pak, err := app.state.CreatePreAuthKey(types.UserID(user.ID), true, false, nil, nil) // reusable=true
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require.NoError(t, err)
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require.True(t, pak.Reusable)
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machineKey := key.NewMachine()
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nodeKey := key.NewNode()
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// Initial registration
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initialReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: pak.Key,
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},
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NodeKey: nodeKey.Public(),
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "reusable-test-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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initialResp, err := app.handleRegister(context.Background(), initialReq, machineKey.Public())
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require.NoError(t, err)
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require.NotNil(t, initialResp)
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assert.True(t, initialResp.MachineAuthorized)
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// Node restart - re-registration with reusable key
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restartReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: pak.Key, // Reusable key
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},
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NodeKey: nodeKey.Public(),
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "reusable-test-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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restartResp, err := app.handleRegister(context.Background(), restartReq, machineKey.Public())
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require.NoError(t, err, "reusable key should allow re-registration")
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require.NotNil(t, restartResp)
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assert.True(t, restartResp.MachineAuthorized)
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assert.False(t, restartResp.NodeKeyExpired)
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}
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// TestNodeReregistrationWithExpiredPreAuthKey tests that truly expired keys
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// are still rejected even for existing nodes.
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func TestNodeReregistrationWithExpiredPreAuthKey(t *testing.T) {
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t.Parallel()
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app := createTestApp(t)
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user := app.state.CreateUserForTest("test-user")
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expiry := time.Now().Add(-1 * time.Hour) // Already expired
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pak, err := app.state.CreatePreAuthKey(types.UserID(user.ID), true, false, &expiry, nil)
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require.NoError(t, err)
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machineKey := key.NewMachine()
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nodeKey := key.NewNode()
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// Try to register with expired key
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req := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: pak.Key,
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},
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NodeKey: nodeKey.Public(),
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "expired-key-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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_, err = app.handleRegister(context.Background(), req, machineKey.Public())
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assert.Error(t, err, "expired pre-auth key should be rejected")
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assert.Contains(t, err.Error(), "authkey expired", "error should mention key expiration")
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}
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// TestGitHubIssue2830_ExistingNodeCanReregisterWithUsedPreAuthKey tests that an existing node
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// can re-register using a pre-auth key that's already marked as Used=true, as long as:
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// 1. The node is re-registering with the same MachineKey it originally used
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// 2. The node is using the same pre-auth key it was originally registered with (AuthKeyID matches)
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//
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// This is the fix for GitHub issue #2830: https://github.com/juanfont/headscale/issues/2830
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//
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// Background: When Docker/Kubernetes containers restart, they keep their persistent state
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// (including the MachineKey), but container entrypoints unconditionally run:
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// tailscale up --authkey=$TS_AUTHKEY
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//
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// This caused nodes to be rejected after restart because the pre-auth key was already
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// marked as Used=true from the initial registration. The fix allows re-registration of
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// existing nodes with their own used keys.
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func TestGitHubIssue2830_ExistingNodeCanReregisterWithUsedPreAuthKey(t *testing.T) {
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app := createTestApp(t)
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// Create a user
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user := app.state.CreateUserForTest("testuser")
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// Create a SINGLE-USE pre-auth key (reusable=false)
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// This is the type of key that triggers the bug in issue #2830
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preAuthKey, err := app.state.CreatePreAuthKey(types.UserID(user.ID), false, false, nil, nil)
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require.NoError(t, err)
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require.False(t, preAuthKey.Reusable, "Pre-auth key must be single-use to test issue #2830")
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require.False(t, preAuthKey.Used, "Pre-auth key should not be used yet")
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// Generate node keys for the client
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machineKey := key.NewMachine()
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nodeKey := key.NewNode()
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// Step 1: Initial registration with the pre-auth key
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// This simulates the first time the container starts and runs 'tailscale up --authkey=...'
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initialReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: preAuthKey.Key,
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},
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NodeKey: nodeKey.Public(),
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "issue-2830-test-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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initialResp, err := app.handleRegisterWithAuthKey(initialReq, machineKey.Public())
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require.NoError(t, err, "Initial registration should succeed")
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require.True(t, initialResp.MachineAuthorized, "Node should be authorized after initial registration")
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require.NotNil(t, initialResp.User, "User should be set in response")
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require.Equal(t, "testuser", initialResp.User.DisplayName, "User should match the pre-auth key's user")
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// Verify the pre-auth key is now marked as Used
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updatedKey, err := app.state.GetPreAuthKey(preAuthKey.Key)
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require.NoError(t, err)
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require.True(t, updatedKey.Used, "Pre-auth key should be marked as Used after initial registration")
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// Step 2: Container restart scenario
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// The container keeps its MachineKey (persistent state), but the entrypoint script
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// unconditionally runs 'tailscale up --authkey=$TS_AUTHKEY' again
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//
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// WITHOUT THE FIX: This would fail with "authkey already used" error
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// WITH THE FIX: This succeeds because it's the same node re-registering with its own key
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// Simulate sending the same RegisterRequest again (same MachineKey, same AuthKey)
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// This is exactly what happens when a container restarts
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reregisterReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: preAuthKey.Key, // Same key, now marked as Used=true
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},
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NodeKey: nodeKey.Public(), // Same NodeKey
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "issue-2830-test-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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reregisterResp, err := app.handleRegisterWithAuthKey(reregisterReq, machineKey.Public()) // Same MachineKey
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require.NoError(t, err, "Re-registration with same MachineKey and used pre-auth key should succeed (fixes #2830)")
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require.True(t, reregisterResp.MachineAuthorized, "Node should remain authorized after re-registration")
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require.NotNil(t, reregisterResp.User, "User should be set in re-registration response")
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require.Equal(t, "testuser", reregisterResp.User.DisplayName, "User should remain the same")
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// Verify that only ONE node was created (not a duplicate)
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nodes := app.state.ListNodesByUser(types.UserID(user.ID))
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require.Equal(t, 1, nodes.Len(), "Should have exactly one node (no duplicates created)")
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require.Equal(t, "issue-2830-test-node", nodes.At(0).Hostname(), "Node hostname should match")
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// Step 3: Verify that a DIFFERENT machine cannot use the same used key
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// This ensures we didn't break the security model - only the original node can re-register
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differentMachineKey := key.NewMachine()
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differentNodeKey := key.NewNode()
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attackReq := tailcfg.RegisterRequest{
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Auth: &tailcfg.RegisterResponseAuth{
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AuthKey: preAuthKey.Key, // Try to use the same key
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},
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NodeKey: differentNodeKey.Public(),
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Hostinfo: &tailcfg.Hostinfo{
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Hostname: "attacker-node",
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},
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Expiry: time.Now().Add(24 * time.Hour),
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}
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_, err = app.handleRegisterWithAuthKey(attackReq, differentMachineKey.Public())
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require.Error(t, err, "Different machine should NOT be able to use the same used pre-auth key")
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require.Contains(t, err.Error(), "already used", "Error should indicate key is already used")
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// Verify still only one node (the original one)
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nodesAfterAttack := app.state.ListNodesByUser(types.UserID(user.ID))
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require.Equal(t, 1, nodesAfterAttack.Len(), "Should still have exactly one node (attack prevented)")
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}
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