OAuth connector

Dockerfile

@@ -29,8 +29,8 @@ ARG TARGETVARIANT
 ENV GOMPLATE_VERSION=v3.9.0
 
 RUN wget -O /usr/local/bin/gomplate \
-  "https://github.com/hairyhenderson/gomplate/releases/download/${GOMPLATE_VERSION}/gomplate_${TARGETOS:-linux}-${TARGETARCH:-amd64}${TARGETVARIANT}" \
-  && chmod +x /usr/local/bin/gomplate
+    "https://github.com/hairyhenderson/gomplate/releases/download/${GOMPLATE_VERSION}/gomplate_${TARGETOS:-linux}-${TARGETARCH:-amd64}${TARGETVARIANT}" \
+    && chmod +x /usr/local/bin/gomplate
 
 
 FROM alpine:3.14.3

README.md

@@ -71,6 +71,7 @@ Dex implements the following connectors:
 | [SAML 2.0](https://dexidp.io/docs/connectors/saml/) | no | yes | no | stable | WARNING: Unmaintained and likely vulnerable to auth bypasses ([#1884](https://github.com/dexidp/dex/discussions/1884)) |
 | [GitLab](https://dexidp.io/docs/connectors/gitlab/) | yes | yes | yes | beta | |
 | [OpenID Connect](https://dexidp.io/docs/connectors/oidc/) | yes | yes | yes | beta | Includes Salesforce, Azure, etc. |
+| [OAuth 2.0](https://dexidp.io/docs/connectors/oauth/) | no | yes | yes | alpha | |
 | [Google](https://dexidp.io/docs/connectors/google/) | yes | yes | yes | alpha | |
 | [LinkedIn](https://dexidp.io/docs/connectors/linkedin/) | yes | no | no | beta | |
 | [Microsoft](https://dexidp.io/docs/connectors/microsoft/) | yes | yes | no | beta | |

connector/oauth/oauth.go

@@ -0,0 +1,292 @@
+package oauth
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"golang.org/x/oauth2"
+
+	"github.com/dexidp/dex/connector"
+	"github.com/dexidp/dex/pkg/log"
+)
+
+type oauthConnector struct {
+	clientID             string
+	clientSecret         string
+	redirectURI          string
+	tokenURL             string
+	authorizationURL     string
+	userInfoURL          string
+	scopes               []string
+	userIDKey            string
+	userNameKey          string
+	preferredUsernameKey string
+	emailKey             string
+	emailVerifiedKey     string
+	groupsKey            string
+	httpClient           *http.Client
+	logger               log.Logger
+}
+
+type connectorData struct {
+	AccessToken string
+}
+
+type Config struct {
+	ClientID           string   `json:"clientID"`
+	ClientSecret       string   `json:"clientSecret"`
+	RedirectURI        string   `json:"redirectURI"`
+	TokenURL           string   `json:"tokenURL"`
+	AuthorizationURL   string   `json:"authorizationURL"`
+	UserInfoURL        string   `json:"userInfoURL"`
+	Scopes             []string `json:"scopes"`
+	RootCAs            []string `json:"rootCAs"`
+	InsecureSkipVerify bool     `json:"insecureSkipVerify"`
+	UserIDKey          string   `json:"userIDKey"` // defaults to "id"
+	ClaimMapping       struct {
+		UserNameKey          string `json:"userNameKey"`          // defaults to "user_name"
+		PreferredUsernameKey string `json:"preferredUsernameKey"` // defaults to "preferred_username"
+		GroupsKey            string `json:"groupsKey"`            // defaults to "groups"
+		EmailKey             string `json:"emailKey"`             // defaults to "email"
+		EmailVerifiedKey     string `json:"emailVerifiedKey"`     // defaults to "email_verified"
+	} `json:"claimMapping"`
+}
+
+func (c *Config) Open(id string, logger log.Logger) (connector.Connector, error) {
+	var err error
+
+	userIDKey := c.UserIDKey
+	if userIDKey == "" {
+		userIDKey = "id"
+	}
+
+	userNameKey := c.ClaimMapping.UserNameKey
+	if userNameKey == "" {
+		userNameKey = "user_name"
+	}
+
+	preferredUsernameKey := c.ClaimMapping.PreferredUsernameKey
+	if preferredUsernameKey == "" {
+		preferredUsernameKey = "preferred_username"
+	}
+
+	groupsKey := c.ClaimMapping.GroupsKey
+	if groupsKey == "" {
+		groupsKey = "groups"
+	}
+
+	emailKey := c.ClaimMapping.EmailKey
+	if emailKey == "" {
+		emailKey = "email"
+	}
+
+	emailVerifiedKey := c.ClaimMapping.EmailVerifiedKey
+	if emailVerifiedKey == "" {
+		emailVerifiedKey = "email_verified"
+	}
+
+	oauthConn := &oauthConnector{
+		clientID:             c.ClientID,
+		clientSecret:         c.ClientSecret,
+		tokenURL:             c.TokenURL,
+		authorizationURL:     c.AuthorizationURL,
+		userInfoURL:          c.UserInfoURL,
+		scopes:               c.Scopes,
+		redirectURI:          c.RedirectURI,
+		logger:               logger,
+		userIDKey:            userIDKey,
+		userNameKey:          userNameKey,
+		preferredUsernameKey: preferredUsernameKey,
+		groupsKey:            groupsKey,
+		emailKey:             emailKey,
+		emailVerifiedKey:     emailVerifiedKey,
+	}
+
+	oauthConn.httpClient, err = newHTTPClient(c.RootCAs, c.InsecureSkipVerify)
+	if err != nil {
+		return nil, err
+	}
+
+	return oauthConn, err
+}
+
+func newHTTPClient(rootCAs []string, insecureSkipVerify bool) (*http.Client, error) {
+	pool, err := x509.SystemCertPool()
+	if err != nil {
+		return nil, err
+	}
+
+	tlsConfig := tls.Config{RootCAs: pool, InsecureSkipVerify: insecureSkipVerify}
+	for _, rootCA := range rootCAs {
+		rootCABytes, err := os.ReadFile(rootCA)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read root-ca: %v", err)
+		}
+		if !tlsConfig.RootCAs.AppendCertsFromPEM(rootCABytes) {
+			return nil, fmt.Errorf("no certs found in root CA file %q", rootCA)
+		}
+	}
+
+	return &http.Client{
+		Transport: &http.Transport{
+			TLSClientConfig: &tlsConfig,
+			Proxy:           http.ProxyFromEnvironment,
+			DialContext: (&net.Dialer{
+				Timeout:   30 * time.Second,
+				KeepAlive: 30 * time.Second,
+				DualStack: true,
+			}).DialContext,
+			MaxIdleConns:          100,
+			IdleConnTimeout:       90 * time.Second,
+			TLSHandshakeTimeout:   10 * time.Second,
+			ExpectContinueTimeout: 1 * time.Second,
+		},
+	}, nil
+}
+
+func (c *oauthConnector) LoginURL(scopes connector.Scopes, callbackURL, state string) (string, error) {
+	if c.redirectURI != callbackURL {
+		return "", fmt.Errorf("expected callback URL %q did not match the URL in the config %q", callbackURL, c.redirectURI)
+	}
+
+	oauth2Config := &oauth2.Config{
+		ClientID:     c.clientID,
+		ClientSecret: c.clientSecret,
+		Endpoint:     oauth2.Endpoint{TokenURL: c.tokenURL, AuthURL: c.authorizationURL},
+		RedirectURL:  c.redirectURI,
+		Scopes:       c.scopes,
+	}
+
+	return oauth2Config.AuthCodeURL(state), nil
+}
+
+func (c *oauthConnector) HandleCallback(s connector.Scopes, r *http.Request) (identity connector.Identity, err error) {
+	q := r.URL.Query()
+	if errType := q.Get("error"); errType != "" {
+		return identity, errors.New(q.Get("error_description"))
+	}
+
+	oauth2Config := &oauth2.Config{
+		ClientID:     c.clientID,
+		ClientSecret: c.clientSecret,
+		Endpoint:     oauth2.Endpoint{TokenURL: c.tokenURL, AuthURL: c.authorizationURL},
+		RedirectURL:  c.redirectURI,
+		Scopes:       c.scopes,
+	}
+
+	ctx := context.WithValue(r.Context(), oauth2.HTTPClient, c.httpClient)
+
+	token, err := oauth2Config.Exchange(ctx, q.Get("code"))
+	if err != nil {
+		return identity, fmt.Errorf("OAuth connector: failed to get token: %v", err)
+	}
+
+	client := oauth2.NewClient(ctx, oauth2.StaticTokenSource(token))
+
+	userInfoResp, err := client.Get(c.userInfoURL)
+	if err != nil {
+		return identity, fmt.Errorf("OAuth Connector: failed to execute request to userinfo: %v", err)
+	}
+	defer userInfoResp.Body.Close()
+
+	if userInfoResp.StatusCode != http.StatusOK {
+		return identity, fmt.Errorf("OAuth Connector: failed to execute request to userinfo: status %d", userInfoResp.StatusCode)
+	}
+
+	var userInfoResult map[string]interface{}
+	err = json.NewDecoder(userInfoResp.Body).Decode(&userInfoResult)
+	if err != nil {
+		return identity, fmt.Errorf("OAuth Connector: failed to parse userinfo: %v", err)
+	}
+
+	userID, found := userInfoResult[c.userIDKey].(string)
+	if !found {
+		return identity, fmt.Errorf("OAuth Connector: not found %v claim", c.userIDKey)
+	}
+
+	identity.UserID = userID
+	identity.Username, _ = userInfoResult[c.userNameKey].(string)
+	identity.PreferredUsername, _ = userInfoResult[c.preferredUsernameKey].(string)
+	identity.Email, _ = userInfoResult[c.emailKey].(string)
+	identity.EmailVerified, _ = userInfoResult[c.emailVerifiedKey].(bool)
+
+	if s.Groups {
+		groups := map[string]struct{}{}
+
+		c.addGroupsFromMap(groups, userInfoResult)
+		c.addGroupsFromToken(groups, token.AccessToken)
+
+		for groupName := range groups {
+			identity.Groups = append(identity.Groups, groupName)
+		}
+	}
+
+	if s.OfflineAccess {
+		data := connectorData{AccessToken: token.AccessToken}
+		connData, err := json.Marshal(data)
+		if err != nil {
+			return identity, fmt.Errorf("OAuth Connector: failed to parse connector data for offline access: %v", err)
+		}
+		identity.ConnectorData = connData
+	}
+
+	return identity, nil
+}
+
+func (c *oauthConnector) addGroupsFromMap(groups map[string]struct{}, result map[string]interface{}) error {
+	groupsClaim, ok := result[c.groupsKey].([]interface{})
+	if !ok {
+		return errors.New("cannot convert to slice")
+	}
+
+	for _, group := range groupsClaim {
+		if groupString, ok := group.(string); ok {
+			groups[groupString] = struct{}{}
+		}
+		if groupMap, ok := group.(map[string]interface{}); ok {
+			if groupName, ok := groupMap["name"].(string); ok {
+				groups[groupName] = struct{}{}
+			}
+		}
+	}
+
+	return nil
+}
+
+func (c *oauthConnector) addGroupsFromToken(groups map[string]struct{}, token string) error {
+	parts := strings.Split(token, ".")
+	if len(parts) < 2 {
+		return errors.New("invalid token")
+	}
+
+	decoded, err := decode(parts[1])
+	if err != nil {
+		return err
+	}
+
+	var claimsMap map[string]interface{}
+	err = json.Unmarshal(decoded, &claimsMap)
+	if err != nil {
+		return err
+	}
+
+	return c.addGroupsFromMap(groups, claimsMap)
+}
+
+func decode(seg string) ([]byte, error) {
+	if l := len(seg) % 4; l > 0 {
+		seg += strings.Repeat("=", 4-l)
+	}
+
+	return base64.URLEncoding.DecodeString(seg)
+}