Add option to enable groups for oidc connectors

There's been some discussion in dexidp#1065 regarding what to do about
refreshing groups. As it stands today dex doesn't update any of the
claims on refresh (groups would just be another one). The main concern
with enabling it is that group claims may change more frequently. While
we continue to wait on the upstream refresh flows, this adds an option
to enable the group claim. This is disabled by default (so no behavioral
change) but enables those that are willing to have the delay in group
claim change to use oidc IDPs.

Workaround to dexidp#1065

Documentation/connectors/oidc.md

@@ -61,6 +61,13 @@ connectors:
     # This can be overridden with the below option
     # insecureSkipEmailVerified: true 
 
+    # Groups claims (like the rest of oidc claims through dex) only refresh when the id token is refreshed
+    # meaning the regular refresh flow doesn't update the groups claim. As such by default the oidc connector
+    # doesn't allow groups claims. If you are okay with having potentially stale group claims you can use
+    # this option to enable groups claims through the oidc connector on a per-connector basis.
+    # This can be overridden with the below option
+    # insecureEnableGroups: true
+
     # When enabled, the OpenID Connector will query the UserInfo endpoint for additional claims. UserInfo claims
     # take priority over claims returned by the IDToken. This option should be used when the IDToken doesn't contain
     # all the claims requested.

connector/oidc/oidc.go

@@ -40,6 +40,9 @@ type Config struct {
 	// Override the value of email_verifed to true in the returned claims
 	InsecureSkipEmailVerified bool `json:"insecureSkipEmailVerified"`
 
+	// InsecureEnableGroups enables groups claims. This is disabled by default until https://github.com/dexidp/dex/issues/1065 is resolved
+	InsecureEnableGroups bool `json:"insecureEnableGroups"`
+
 	// GetUserInfo uses the userinfo endpoint to get additional claims for
 	// the token. This is especially useful where upstreams return "thin"
 	// id tokens
@@ -132,6 +135,7 @@ func (c *Config) Open(id string, logger log.Logger) (conn connector.Connector, e
 		cancel:                    cancel,
 		hostedDomains:             c.HostedDomains,
 		insecureSkipEmailVerified: c.InsecureSkipEmailVerified,
+		insecureEnableGroups:      c.InsecureEnableGroups,
 		getUserInfo:               c.GetUserInfo,
 		userIDKey:                 c.UserIDKey,
 		userNameKey:               c.UserNameKey,
@@ -152,6 +156,7 @@ type oidcConnector struct {
 	logger                    log.Logger
 	hostedDomains             []string
 	insecureSkipEmailVerified bool
+	insecureEnableGroups      bool
 	getUserInfo               bool
 	userIDKey                 string
 	userNameKey               string
@@ -274,6 +279,19 @@ func (c *oidcConnector) HandleCallback(s connector.Scopes, r *http.Request) (ide
 		identity.UserID = userID
 	}
 
+	if c.insecureEnableGroups {
+		vs, ok := claims["groups"].([]interface{})
+		if ok {
+			for _, v := range vs {
+				if s, ok := v.(string); ok {
+					identity.Groups = append(identity.Groups, s)
+				} else {
+					return identity, errors.New("malformed \"groups\" claim")
+				}
+			}
+		}
+	}
+
 	return identity, nil
 }