oidc driver: get user from user provider (#3288)

* fix oidc driver for non standard claims in user response

* fix username

* fix error

* fix client

* add changelog

changelog/unreleased/oidc-users.md

@@ -0,0 +1,6 @@
+Bugfix: Get user from user provider in oidc driver
+
+For oidc providers that only respond with standard claims,
+use the user provider to get the user.
+
+https://github.com/cs3org/reva/pull/3055

pkg/auth/manager/oidc/oidc.go

@@ -199,12 +199,6 @@ func (am *mgr) Authenticate(ctx context.Context, clientID, clientSecret string)
 		return nil, nil, fmt.Errorf("no \"email\" attribute found in userinfo: maybe the client did not request the oidc \"email\"-scope")
 	}
 
-	uid, _ := claims[am.c.UIDClaim].(float64)
-	claims[am.c.UIDClaim] = int64(uid) // in case the uid claim is missing and a mapping is to be performed, resolveUser() will populate it
-	// Note that if not, will silently carry a user with 0 uid, potentially problematic with storage providers
-	gid, _ := claims[am.c.GIDClaim].(float64)
-	claims[am.c.GIDClaim] = int64(gid)
-
 	err = am.resolveUser(ctx, claims)
 	if err != nil {
 		return nil, nil, errors.Wrapf(err, "oidc: error resolving username for external user '%v'", claims["email"])
@@ -261,6 +255,15 @@ func (am *mgr) Authenticate(ctx context.Context, clientID, clientSecret string)
 	return u, scopes, nil
 }
 
+func (am *mgr) getUserID(claims map[string]interface{}) (int64, int64) {
+	uidf, _ := claims[am.c.UIDClaim].(float64)
+	uid := int64(uidf)
+
+	gidf, _ := claims[am.c.GIDClaim].(float64)
+	gid := int64(gidf)
+	return uid, gid
+}
+
 func (am *mgr) getOAuthCtx(ctx context.Context) context.Context {
 	// Sometimes for testing we need to skip the TLS check, that's why we need a
 	// custom HTTP client.
@@ -300,9 +303,16 @@ func (am *mgr) getOIDCProvider(ctx context.Context) (*oidc.Provider, error) {
 }
 
 func (am *mgr) resolveUser(ctx context.Context, claims map[string]interface{}) error {
-	if len(am.oidcUsersMapping) > 0 {
-		var username string
+	var (
+		claim   string
+		value   string
+		resolve bool
+	)
 
+	uid, gid := am.getUserID(claims)
+
+	if len(am.oidcUsersMapping) > 0 {
+		claim = "username"
 		// map and discover the user's username when a mapping is defined
 		if claims[am.c.GroupClaim] == nil {
 			// we are required to perform a user mapping but the group claim is not available
@@ -324,32 +334,41 @@ func (am *mgr) resolveUser(ctx context.Context, claims map[string]interface{}) e
 			return errtypes.PermissionDenied("no user mapping found for the given group claim(s)")
 		}
 		for _, m := range intersection {
-			username = am.oidcUsersMapping[m.(string)].Username
+			value = am.oidcUsersMapping[m.(string)].Username
 		}
+		resolve = true
+	} else if uid == 0 || gid == 0 {
+		claim = "mail"
+		value = claims["email"].(string)
+		resolve = true
+	}
 
-		upsc, err := pool.GetUserProviderServiceClient(pool.Endpoint(am.c.GatewaySvc))
-		if err != nil {
-			return errors.Wrap(err, "error getting user provider grpc client")
-		}
-		getUserByClaimResp, err := upsc.GetUserByClaim(ctx, &user.GetUserByClaimRequest{
-			Claim: "username",
-			Value: username,
-		})
-		if err != nil {
-			return errors.Wrapf(err, "error getting user by username '%v'", username)
-		}
-		if getUserByClaimResp.Status.Code != rpc.Code_CODE_OK {
-			return status.NewErrorFromCode(getUserByClaimResp.Status.Code, "oidc")
-		}
+	if !resolve {
+		return nil
+	}
 
-		// take the properties of the mapped target user to override the claims
-		claims["preferred_username"] = username
-		claims[am.c.IDClaim] = getUserByClaimResp.GetUser().GetId().OpaqueId
-		claims["iss"] = getUserByClaimResp.GetUser().GetId().Idp
-		claims[am.c.UIDClaim] = getUserByClaimResp.GetUser().UidNumber
-		claims[am.c.GIDClaim] = getUserByClaimResp.GetUser().GidNumber
-		appctx.GetLogger(ctx).Debug().Str("username", username).Interface("claims", claims).Msg("resolveUser: claims overridden from mapped user")
+	upsc, err := pool.GetGatewayServiceClient(pool.Endpoint(am.c.GatewaySvc))
+	if err != nil {
+		return errors.Wrap(err, "error getting user provider grpc client")
 	}
+	getUserByClaimResp, err := upsc.GetUserByClaim(ctx, &user.GetUserByClaimRequest{
+		Claim: claim,
+		Value: value,
+	})
+	if err != nil {
+		return errors.Wrapf(err, "error getting user by %s '%v'", claim, value)
+	}
+	if getUserByClaimResp.Status.Code != rpc.Code_CODE_OK {
+		return status.NewErrorFromCode(getUserByClaimResp.Status.Code, "oidc")
+	}
+
+	// take the properties of the mapped target user to override the claims
+	claims["preferred_username"] = getUserByClaimResp.GetUser().Username
+	claims[am.c.IDClaim] = getUserByClaimResp.GetUser().GetId().OpaqueId
+	claims["iss"] = getUserByClaimResp.GetUser().GetId().Idp
+	claims[am.c.UIDClaim] = getUserByClaimResp.GetUser().UidNumber
+	claims[am.c.GIDClaim] = getUserByClaimResp.GetUser().GidNumber
+	appctx.GetLogger(ctx).Debug().Str("username", value).Interface("claims", claims).Msg("resolveUser: claims overridden from mapped user")
 	return nil
 }