[management] Deny reverse proxy access to pending and blocked users (#7105)

A user in the Pending Approval state could complete SSO and reach any SSO-protected reverse proxy service distributed to a group they belong to, including the All Users group. The reverse proxy authorization path checked the session token signature, that the user exists, that the user's account matches the service's account, and group membership — never the user's account status. The REST API (`permissions/manager.go`) and peer registration both gate on that state, but the proxy gRPC service does not go through the permissions manager, so neither gate applied. A pending user is persisted as blocked and pending approval, so blocked users reached those services the same way. `ValidateSession` now denies on account status, reporting `pending_approval` or `user_blocked` so the proxy access log and the denied page carry the cause rather than a generic refusal. `GenerateSessionToken` refuses to mint a token for such a user at all, so the browser never receives a session cookie and the OIDC callback can tell the user why instead of showing "Service configuration error". `ValidateUserGroupAccess` and `ValidateTunnelPeer` close the same gap; for the tunnel path this covers a user blocked after their peer was registered, since peer group membership alone kept mesh-origin access open. A single helper produces both the denied reason for the RPC responses and the sentinel error for the error-returning callers, so the four entry points cannot drift apart. A user the store cannot resolve is denied rather than passed through. One thing deliberately left out: session cookies are validated locally by the proxy against the service public key with no management round-trip, so a cookie issued before a user is blocked stays valid until it expires (24h by default). That is a revocation-propagation problem rather than this authorization gap, and every option for it (per-request validation with a cache, short-lived tokens with refresh, push-based revocation) changes the proxy hot path or the proxy/management protocol. Worth its own ticket.
2026-10-07 05:59:06 +02:00 · 2026-08-08 20:48:34 +09:00
parent 179e8f6e13
commit f65f7b347e
5 changed files with 735 additions and 99 deletions
@@ -119,11 +119,13 @@ func (m *mockReverseProxyManager) GetClusters(_ context.Context, _, _ string) ([
 }

 type mockUsersManager struct {
-	users map[string]*types.User
-	err   error
+	users        map[string]*types.User
+	err          error
+	getUserCalls int
 }

 func (m *mockUsersManager) GetUser(ctx context.Context, userID string) (*types.User, error) {
+	m.getUserCalls++
 	if m.err != nil {
 		return nil, m.err
 	}
@@ -350,6 +352,64 @@ func TestValidateUserGroupAccess(t *testing.T) {
 			},
 			expectErr: false,
 		},
+		{
+			name:   "user pending approval denied despite group membership",
+			domain: "app.example.com",
+			userID: "user1",
+			proxiesByAccount: map[string][]*service.Service{
+				"account1": {{
+					Domain:    "app.example.com",
+					AccountID: "account1",
+					Auth: service.AuthConfig{
+						BearerAuth: &service.BearerAuthConfig{
+							Enabled:            true,
+							DistributionGroups: []string{"group1"},
+						},
+					},
+				}},
+			},
+			users: map[string]*types.User{
+				// The approval flow stores a pending user as blocked as well.
+				"user1": {Id: "user1", AccountID: "account1", AutoGroups: []string{"group1"}, Blocked: true, PendingApproval: true},
+			},
+			expectErr:    true,
+			expectErrMsg: "user pending approval",
+		},
+		{
+			name:   "blocked user denied despite group membership",
+			domain: "app.example.com",
+			userID: "user1",
+			proxiesByAccount: map[string][]*service.Service{
+				"account1": {{
+					Domain:    "app.example.com",
+					AccountID: "account1",
+					Auth: service.AuthConfig{
+						BearerAuth: &service.BearerAuthConfig{
+							Enabled:            true,
+							DistributionGroups: []string{"group1"},
+						},
+					},
+				}},
+			},
+			users: map[string]*types.User{
+				"user1": {Id: "user1", AccountID: "account1", AutoGroups: []string{"group1"}, Blocked: true},
+			},
+			expectErr:    true,
+			expectErrMsg: "user blocked",
+		},
+		{
+			name:   "blocked user denied on a service with no auth configured",
+			domain: "app.example.com",
+			userID: "user1",
+			proxiesByAccount: map[string][]*service.Service{
+				"account1": {{Domain: "app.example.com", AccountID: "account1", Auth: service.AuthConfig{}}},
+			},
+			users: map[string]*types.User{
+				"user1": {Id: "user1", AccountID: "account1", Blocked: true},
+			},
+			expectErr:    true,
+			expectErrMsg: "user blocked",
+		},
 		{
 			name:             "proxy manager error",
 			domain:           "app.example.com",
@@ -421,17 +481,18 @@ func TestValidateTunnelPeerUserEmailEnrichment(t *testing.T) {
 	storedUserNoEmail := map[string]*types.User{userID: {Id: userID, AccountID: accountID, Email: ""}}

 	tests := []struct {
-		name         string
-		peerUserID   string
-		storedUsers  map[string]*types.User
-		storedErr    error
-		noIdP        bool
-		idpEmail     string
-		idpHasData   bool
-		idpErr       error
-		expectEmail  string
-		expectUserID string
-		expectIdPHit bool
+		name               string
+		peerUserID         string
+		storedUsers        map[string]*types.User
+		storedErr          error
+		noIdP              bool
+		idpEmail           string
+		idpHasData         bool
+		idpErr             error
+		expectEmail        string
+		expectUserID       string
+		expectIdPHit       bool
+		expectDeniedReason string
 	}{
 		{
 			name:         "idp email wins over stored email",
@@ -490,14 +551,17 @@ func TestValidateTunnelPeerUserEmailEnrichment(t *testing.T) {
 			expectIdPHit: true,
 		},
 		{
-			name:         "idp email when stored user missing keeps peer.UserID as principal",
-			peerUserID:   userID,
-			storedUsers:  map[string]*types.User{},
-			idpEmail:     "idp@example.com",
-			idpHasData:   true,
-			expectEmail:  "idp@example.com",
-			expectUserID: userID,
-			expectIdPHit: true,
+			// The identity still resolves from the IdP, but an owner the store
+			// cannot resolve denies the fast-path rather than granting it.
+			name:               "idp email when stored user missing keeps peer.UserID as principal",
+			peerUserID:         userID,
+			storedUsers:        map[string]*types.User{},
+			idpEmail:           "idp@example.com",
+			idpHasData:         true,
+			expectEmail:        "idp@example.com",
+			expectUserID:       userID,
+			expectIdPHit:       true,
+			expectDeniedReason: deniedReasonUserNotFound,
 		},
 		{
 			name:         "unlinked peer uses peer name and never consults idp",
@@ -545,9 +609,13 @@ func TestValidateTunnelPeerUserEmailEnrichment(t *testing.T) {

 			require.NoError(t, err)
 			require.NotNil(t, resp)
-			assert.True(t, resp.GetValid(), "expected access granted")
+			assert.Equal(t, tt.expectDeniedReason == "", resp.GetValid(), "unexpected access decision")
+			assert.Equal(t, tt.expectDeniedReason, resp.GetDeniedReason(), "unexpected denied reason")
 			assert.Equal(t, tt.expectEmail, resp.GetUserEmail())
 			assert.Equal(t, tt.expectUserID, resp.GetUserId())
+			if tt.expectDeniedReason != "" {
+				assert.Empty(t, resp.GetSessionToken(), "a denied peer must not receive a session token")
+			}

 			if idpMock != nil {
 				if tt.expectIdPHit {
@@ -562,6 +630,121 @@ func TestValidateTunnelPeerUserEmailEnrichment(t *testing.T) {
 	}
 }

+// TestDeniedReasonValues pins the wire values of the account status denied
+// reasons. The proxy logs them and operators filter access logs on them, so a
+// rename is a breaking change rather than an internal detail.
+// TestSameAccount pins the fail-closed behaviour of the account binding: an
+// unset account on either side must never compare equal into a grant.
+func TestSameAccount(t *testing.T) {
+	assert.True(t, sameAccount("account1", "account1"), "matching accounts should bind")
+	assert.False(t, sameAccount("account1", "account2"), "different accounts must not bind")
+	assert.False(t, sameAccount("", ""), "two unset accounts must not bind")
+	assert.False(t, sameAccount("account1", ""), "an unset service account must not bind")
+	assert.False(t, sameAccount("", "account1"), "an unset user account must not bind")
+}
+
+func TestDeniedReasonValues(t *testing.T) {
+	assert.Equal(t, "pending_approval", deniedReasonPendingApproval, "pending approval denied reason wire value")
+	assert.Equal(t, "user_blocked", deniedReasonUserBlocked, "blocked user denied reason wire value")
+	assert.Equal(t, "user_not_found", deniedReasonUserNotFound, "unresolved user denied reason wire value")
+}
+
+// TestValidateTunnelPeerOwnerStatus verifies that the mesh fast-path gates on
+// the account status of the peer's owning user. A peer whose owner was blocked
+// after the peer registered must lose access, while an unlinked machine peer
+// keeps it.
+func TestValidateTunnelPeerOwnerStatus(t *testing.T) {
+	const (
+		domain    = "app.example.com"
+		accountID = "account1"
+		peerID    = "peer1"
+		peerName  = "peer-display-name"
+		userID    = "user1"
+	)
+
+	tests := []struct {
+		name               string
+		peerUserID         string
+		owner              *types.User
+		expectDeniedReason string
+		expectEmail        string
+	}{
+		{
+			name:       "active owner allowed",
+			peerUserID: userID,
+			owner:      &types.User{Id: userID, AccountID: accountID, Email: "user@example.com"},
+		},
+		{
+			name:               "owner pending approval denied",
+			peerUserID:         userID,
+			owner:              &types.User{Id: userID, AccountID: accountID, Email: "user@example.com", Blocked: true, PendingApproval: true},
+			expectDeniedReason: deniedReasonPendingApproval,
+		},
+		{
+			name:               "owner blocked after registering the peer denied",
+			peerUserID:         userID,
+			owner:              &types.User{Id: userID, AccountID: accountID, Email: "user@example.com", Blocked: true},
+			expectDeniedReason: deniedReasonUserBlocked,
+		},
+		{
+			name:       "unlinked machine peer stays allowed",
+			peerUserID: "",
+			owner:      &types.User{Id: userID, AccountID: accountID, Blocked: true},
+		},
+		{
+			// The user lookup is not account-scoped, so a peer row pointing at
+			// another account's user must not resolve into an owner: the peer is
+			// denied and the foreign email never reaches the response.
+			name:               "owner in another account denied and not disclosed",
+			peerUserID:         userID,
+			owner:              &types.User{Id: userID, AccountID: "otherAccount", Email: "foreign@example.com"},
+			expectDeniedReason: deniedReasonUserNotFound,
+			expectEmail:        peerName,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			svc := &service.Service{Domain: domain, AccountID: accountID}
+			usersManager := &mockUsersManager{users: map[string]*types.User{userID: tt.owner}}
+			server := &ProxyServiceServer{
+				serviceManager: &mockReverseProxyManager{
+					proxiesByAccount: map[string][]*service.Service{accountID: {svc}},
+				},
+				peersManager: &mockTunnelPeersManager{
+					peer: &peer.Peer{ID: peerID, Name: peerName, UserID: tt.peerUserID},
+				},
+				usersManager: usersManager,
+			}
+
+			resp, err := server.ValidateTunnelPeer(context.Background(), &proto.ValidateTunnelPeerRequest{
+				Domain:   domain,
+				TunnelIp: "100.64.0.1",
+			})
+
+			require.NoError(t, err)
+			require.NotNil(t, resp)
+			assert.Equal(t, tt.expectDeniedReason, resp.GetDeniedReason(), "unexpected denied reason")
+			assert.Equal(t, tt.expectDeniedReason == "", resp.GetValid(), "unexpected access decision")
+			if tt.expectDeniedReason != "" {
+				assert.Empty(t, resp.GetSessionToken(), "a denied peer must not receive a session token")
+			}
+
+			if tt.expectEmail != "" {
+				assert.Equal(t, tt.expectEmail, resp.GetUserEmail(), "unexpected identity on the response")
+			}
+
+			// The status gate and the identity resolution share one lookup;
+			// an unlinked peer has no owner to look up at all.
+			wantLookups := 1
+			if tt.peerUserID == "" {
+				wantLookups = 0
+			}
+			assert.Equal(t, wantLookups, usersManager.getUserCalls, "owner must be resolved exactly once per request")
+		})
+	}
+}
+
 func TestGetAccountProxyByDomain(t *testing.T) {
 	tests := []struct {
 		name             string