Add OIDC claim names options

CHANGELOG.md

@@ -35,6 +35,7 @@ Use error group handling to ensure tests actually pass [#1535](https://github.co
 Fix hang on SIGTERM [#1492](https://github.com/juanfont/headscale/pull/1492) taken from [#1480](https://github.com/juanfont/headscale/pull/1480)
 Send logs to stderr by default [#1524](https://github.com/juanfont/headscale/pull/1524)
 Fix [TS-2023-006](https://tailscale.com/security-bulletins/#ts-2023-006) security UPnP issue [#1563](https://github.com/juanfont/headscale/pull/1563)
+Add `oidc.groups_claim` and `oidc.email_claim` to allow setting those claim names [#1594](https://github.com/juanfont/headscale/pull/1594)
 
 ## 0.22.3 (2023-05-12)
 

docs/oidc.md

@@ -24,6 +24,11 @@ oidc:
   # It resolves environment variables, making integration to systemd's
   # `LoadCredential` straightforward:
   #client_secret_path: "${CREDENTIALS_DIRECTORY}/oidc_client_secret"
+  # If provided, the name of a custom OIDC claim for specifying user groups. 
+  # The claim value is expected to be a string or array of strings.
+  groups_claim: groups
+  # The OIDC claim to use as the email.
+  email_claim: email
 
   # Customize the scopes used in the OIDC flow, defaults to "openid", "profile" and "email" and add custom query
   # parameters to the Authorize Endpoint request. Scopes default to "openid", "profile" and "email".

hscontrol/oidc.go

@@ -6,6 +6,7 @@ import (
 	"crypto/rand"
 	_ "embed"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"html/template"
@@ -40,14 +41,45 @@ var (
 	errOIDCInvalidNodeState = errors.New(
 		"requested node state key expired before authorisation completed",
 	)
-	errOIDCNodeKeyMissing = errors.New("could not get node key from cache")
+	errOIDCNodeKeyMissing    = errors.New("could not get node key from cache")
+	errOIDCEmailClaimMissing = errors.New("email claim missing from ID Token")
 )
 
 type IDTokenClaims struct {
-	Name     string   `json:"name,omitempty"`
-	Groups   []string `json:"groups,omitempty"`
-	Email    string   `json:"email"`
-	Username string   `json:"preferred_username,omitempty"`
+	// in some cases the groups might be a single value and not a list
+	Groups stringOrArray
+	Email  string
+}
+
+type stringOrArray []string
+
+func (s *stringOrArray) UnmarshalJSON(b []byte) error {
+	var a []string
+	if err := json.Unmarshal(b, &a); err == nil {
+		*s = a
+		return nil
+	}
+	var str string
+	if err := json.Unmarshal(b, &str); err != nil {
+		return err
+	}
+	*s = []string{str}
+	return nil
+}
+
+type rawClaims map[string]json.RawMessage
+
+func (c rawClaims) unmarshalClaim(name string, v interface{}) error {
+	val, ok := c[name]
+	if !ok {
+		return fmt.Errorf("claim not present")
+	}
+	return json.Unmarshal([]byte(val), v)
+}
+
+func (c rawClaims) hasClaim(name string) bool {
+	_, ok := c[name]
+	return ok
 }
 
 func (h *Headscale) initOIDC() error {
@@ -215,7 +247,7 @@ func (h *Headscale) OIDCCallback(
 	// 	return
 	// }
 
-	claims, err := extractIDTokenClaims(writer, idToken)
+	claims, err := extractIDTokenClaims(writer, h.cfg.OIDC, idToken)
 	if err != nil {
 		return
 	}
@@ -355,25 +387,51 @@ func (h *Headscale) verifyIDTokenForOIDCCallback(
 
 func extractIDTokenClaims(
 	writer http.ResponseWriter,
+	cfg types.OIDCConfig,
 	idToken *oidc.IDToken,
 ) (*IDTokenClaims, error) {
 	var claims IDTokenClaims
-	if err := idToken.Claims(&claims); err != nil {
-		util.LogErr(err, "Failed to decode id token claims")
+	var rawClaims rawClaims
+	if err := idToken.Claims(&rawClaims); err != nil {
+		handleClaimError(writer, err)
 
-		writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
-		writer.WriteHeader(http.StatusBadRequest)
-		_, werr := writer.Write([]byte("Failed to decode id token claims"))
-		if werr != nil {
-			util.LogErr(err, "Failed to write response")
-		}
+		return nil, err
+	}
+
+	if !rawClaims.hasClaim(cfg.EmailClaim) {
+		handleClaimError(writer, errOIDCEmailClaimMissing)
+
+		return nil, errOIDCEmailClaimMissing
+	}
+
+	if err := rawClaims.unmarshalClaim(cfg.EmailClaim, &claims.Email); err != nil {
+		handleClaimError(writer, err)
 
 		return nil, err
 	}
 
+	if rawClaims.hasClaim(cfg.GroupsClaim) {
+		if err := rawClaims.unmarshalClaim(cfg.GroupsClaim, &claims.Groups); err != nil {
+			handleClaimError(writer, err)
+
+			return nil, err
+		}
+	}
+
 	return &claims, nil
 }
 
+func handleClaimError(writer http.ResponseWriter, err error) {
+	util.LogErr(err, "Failed to decode id token rawClaims")
+
+	writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	writer.WriteHeader(http.StatusBadRequest)
+	_, werr := writer.Write([]byte("Failed to decode id token rawClaims"))
+	if werr != nil {
+		util.LogErr(err, "Failed to write response")
+	}
+}
+
 // validateOIDCAllowedDomains checks that if AllowedDomains is provided,
 // that the authenticated principal ends with @<alloweddomain>.
 func validateOIDCAllowedDomains(

hscontrol/oidc_test.go

@@ -0,0 +1,164 @@
+package hscontrol
+
+import (
+	"context"
+	"crypto"
+	"crypto/rand"
+	"crypto/rsa"
+	"github.com/coreos/go-oidc/v3/oidc"
+	"github.com/go-jose/go-jose/v3"
+	"github.com/juanfont/headscale/hscontrol/types"
+	"github.com/stretchr/testify/assert"
+	"net/http/httptest"
+	"reflect"
+	"testing"
+)
+
+func Test_extractIDTokenClaims(t *testing.T) {
+	tests := []verificationTest{
+		{
+			name:    "default claim names",
+			idToken: `{"iss":"https://foo", "email": "foo@bar.baz", "groups": ["group1", "group2"]}`,
+			cfg: types.OIDCConfig{
+				EmailClaim:  "email",
+				GroupsClaim: "groups",
+			},
+			want: &IDTokenClaims{
+				Groups: []string{"group1", "group2"},
+				Email:  "foo@bar.baz",
+			},
+			wantErr: false,
+		},
+		{
+			name:    "custom claim names",
+			idToken: `{"iss":"https://foo", "my_custom_claim": "foo@bar.baz", "https://foo.baz/groups": ["group3", "group4"]}`,
+			cfg: types.OIDCConfig{
+				EmailClaim:  "my_custom_claim",
+				GroupsClaim: "https://foo.baz/groups",
+			},
+			want: &IDTokenClaims{
+				Groups: []string{"group3", "group4"},
+				Email:  "foo@bar.baz",
+			},
+			wantErr: false,
+		},
+		{
+			name:    "group claim not present",
+			idToken: `{"iss":"https://foo", "my_custom_claim": "foo@bar.baz"}`,
+			cfg: types.OIDCConfig{
+				EmailClaim:  "my_custom_claim",
+				GroupsClaim: "https://foo.baz/groups",
+			},
+			want: &IDTokenClaims{
+				Email: "foo@bar.baz",
+			},
+			wantErr: false,
+		},
+		{
+			name:    "email claim not present",
+			idToken: `{"iss":"https://foo", "groups": ["group1", "group2"]}`,
+			cfg: types.OIDCConfig{
+				EmailClaim:  "email",
+				GroupsClaim: "groups",
+			},
+			want:    nil,
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			recorder := httptest.NewRecorder()
+			token, err := tt.getToken(t)
+			if err != nil {
+				t.Errorf("could not parse the token: %v", err)
+
+				return
+			}
+
+			if !tt.wantErr {
+				assert.Equal(t, 200, recorder.Result().StatusCode)
+				assert.Empty(t, recorder.Result().Header)
+			}
+
+			got, err := extractIDTokenClaims(recorder, tt.cfg, token)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("extractIDTokenClaims() error = %v, wantErr %v", err, tt.wantErr)
+
+				return
+			}
+
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("extractIDTokenClaims() got = %v, want %v", got, tt.want)
+
+				return
+			}
+		})
+	}
+}
+
+type signingKey struct {
+	keyID string
+	key   interface{}
+	pub   interface{}
+	alg   jose.SignatureAlgorithm
+}
+
+// sign creates a JWS using the private key from the provided payload.
+func (s *signingKey) sign(t testing.TB, payload []byte) string {
+	privKey := &jose.JSONWebKey{Key: s.key, Algorithm: string(s.alg), KeyID: s.keyID}
+
+	signer, err := jose.NewSigner(jose.SigningKey{Algorithm: s.alg, Key: privKey}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	jws, err := signer.Sign(payload)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	data, err := jws.CompactSerialize()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return data
+}
+
+type verificationTest struct {
+	name    string
+	idToken string
+	cfg     types.OIDCConfig
+	want    *IDTokenClaims
+	wantErr bool
+}
+
+func newRSAKey(t testing.TB) *signingKey {
+	priv, err := rsa.GenerateKey(rand.Reader, 1028)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return &signingKey{"", priv, priv.Public(), jose.RS256}
+}
+
+func (v verificationTest) getToken(t *testing.T) (*oidc.IDToken, error) {
+	key := newRSAKey(t)
+	token := key.sign(t, []byte(v.idToken))
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	verifier := oidc.NewVerifier(
+		"https://foo",
+		&oidc.StaticKeySet{PublicKeys: []crypto.PublicKey{key.pub}},
+		&oidc.Config{
+			SkipClientIDCheck:          true,
+			SkipExpiryCheck:            true,
+			SkipIssuerCheck:            true,
+			InsecureSkipSignatureCheck: true,
+		},
+	)
+
+	return verifier.Verify(ctx, token)
+}

hscontrol/types/config.go

@@ -102,6 +102,8 @@ type OIDCConfig struct {
 	AllowedDomains             []string
 	AllowedUsers               []string
 	AllowedGroups              []string
+	GroupsClaim                string
+	EmailClaim                 string
 	StripEmaildomain           bool
 	Expiry                     time.Duration
 	UseExpiryFromToken         bool
@@ -185,6 +187,8 @@ func LoadConfig(path string, isFile bool) error {
 	viper.SetDefault("oidc.strip_email_domain", true)
 	viper.SetDefault("oidc.only_start_if_oidc_is_available", true)
 	viper.SetDefault("oidc.expiry", "180d")
+	viper.SetDefault("oidc.groups_claim", "groups")
+	viper.SetDefault("oidc.email_claim", "email")
 	viper.SetDefault("oidc.use_expiry_from_token", false)
 
 	viper.SetDefault("logtail.enabled", false)
@@ -631,6 +635,8 @@ func GetHeadscaleConfig() (*Config, error) {
 			AllowedDomains:   viper.GetStringSlice("oidc.allowed_domains"),
 			AllowedUsers:     viper.GetStringSlice("oidc.allowed_users"),
 			AllowedGroups:    viper.GetStringSlice("oidc.allowed_groups"),
+			GroupsClaim:      viper.GetString("oidc.groups_claim"),
+			EmailClaim:       viper.GetString("oidc.email_claim"),
 			StripEmaildomain: viper.GetBool("oidc.strip_email_domain"),
 			Expiry: func() time.Duration {
 				// if set to 0, we assume no expiry