OAuth2 provider: support for granular scopes

- `CheckOAuthAccessToken` returns both user ID and additional scopes
- `grantAdditionalScopes` returns AccessTokenScope ready string (grantScopes)
   compiled from requested additional scopes by the client
- `userIDFromToken` sets returned grantScopes (if any) instead of default `all`

modules/setting/oauth2.go

@@ -100,6 +100,7 @@ var OAuth2 = struct {
 	JWTSigningPrivateKeyFile    string `ini:"JWT_SIGNING_PRIVATE_KEY_FILE"`
 	MaxTokenLength              int
 	DefaultApplications         []string
+	EnableAdditionalGrantScopes bool
 }{
 	Enabled:                     true,
 	AccessTokenExpirationTime:   3600,
@@ -109,6 +110,7 @@ var OAuth2 = struct {
 	JWTSigningPrivateKeyFile:    "jwt/private.pem",
 	MaxTokenLength:              math.MaxInt16,
 	DefaultApplications:         []string{"git-credential-oauth", "git-credential-manager", "tea"},
+	EnableAdditionalGrantScopes: false,
 }
 
 func loadOAuth2From(rootCfg ConfigProvider) {

routers/web/user/setting/applications.go

@@ -110,5 +110,6 @@ func loadApplicationsData(ctx *context.Context) {
 			ctx.ServerError("GetOAuth2GrantsByUserID", err)
 			return
 		}
+		ctx.Data["EnableAdditionalGrantScopes"] = setting.OAuth2.EnableAdditionalGrantScopes
 	}
 }

services/auth/basic.go

@@ -72,7 +72,7 @@ func (b *Basic) Verify(req *http.Request, w http.ResponseWriter, store DataStore
 	}
 
 	// check oauth2 token
-	uid := CheckOAuthAccessToken(req.Context(), authToken)
+	uid, _ := CheckOAuthAccessToken(req.Context(), authToken)
 	if uid != 0 {
 		log.Trace("Basic Authorization: Valid OAuthAccessToken for user[%d]", uid)
 

services/auth/oauth2.go

@@ -7,6 +7,7 @@ package auth
 import (
 	"context"
 	"net/http"
+	"slices"
 	"strings"
 	"time"
 
@@ -25,28 +26,69 @@ var (
 	_ Method = &OAuth2{}
 )
 
+// grantAdditionalScopes returns valid scopes coming from grant
+func grantAdditionalScopes(grantScopes string) string {
+	// scopes_supported from templates/user/auth/oidc_wellknown.tmpl
+	scopesSupported := []string{
+		"openid",
+		"profile",
+		"email",
+		"groups",
+	}
+
+	var apiTokenScopes []string
+	for _, apiTokenScope := range strings.Split(grantScopes, " ") {
+		if slices.Index(scopesSupported, apiTokenScope) == -1 {
+			apiTokenScopes = append(apiTokenScopes, apiTokenScope)
+		}
+	}
+
+	if len(apiTokenScopes) == 0 {
+		return ""
+	}
+
+	var additionalGrantScopes []string
+	allScopes := auth_model.AccessTokenScope("all")
+
+	for _, apiTokenScope := range apiTokenScopes {
+		grantScope := auth_model.AccessTokenScope(apiTokenScope)
+		if ok, _ := allScopes.HasScope(grantScope); ok {
+			additionalGrantScopes = append(additionalGrantScopes, apiTokenScope)
+		} else if apiTokenScope == "public-only" {
+			additionalGrantScopes = append(additionalGrantScopes, apiTokenScope)
+		}
+	}
+	if len(additionalGrantScopes) > 0 {
+		return strings.Join(additionalGrantScopes, ",")
+	}
+
+	return ""
+}
+
 // CheckOAuthAccessToken returns uid of user from oauth token
-func CheckOAuthAccessToken(ctx context.Context, accessToken string) int64 {
+// + non default openid scopes requested
+func CheckOAuthAccessToken(ctx context.Context, accessToken string) (int64, string) {
 	// JWT tokens require a "."
 	if !strings.Contains(accessToken, ".") {
-		return 0
+		return 0, ""
 	}
 	token, err := oauth2.ParseToken(accessToken, oauth2.DefaultSigningKey)
 	if err != nil {
 		log.Trace("oauth2.ParseToken: %v", err)
-		return 0
+		return 0, ""
 	}
 	var grant *auth_model.OAuth2Grant
 	if grant, err = auth_model.GetOAuth2GrantByID(ctx, token.GrantID); err != nil || grant == nil {
-		return 0
+		return 0, ""
 	}
 	if token.Type != oauth2.TypeAccessToken {
-		return 0
+		return 0, ""
 	}
 	if token.ExpiresAt.Before(time.Now()) || token.IssuedAt.After(time.Now()) {
-		return 0
+		return 0, ""
 	}
-	return grant.UserID
+	grantScopes := grantAdditionalScopes(grant.Scope)
+	return grant.UserID, grantScopes
 }
 
 // OAuth2 implements the Auth interface and authenticates requests
@@ -92,11 +134,16 @@ func parseToken(req *http.Request) (string, bool) {
 func (o *OAuth2) userIDFromToken(ctx context.Context, tokenSHA string, store DataStore) int64 {
 	// Let's see if token is valid.
 	if strings.Contains(tokenSHA, ".") {
-		uid := CheckOAuthAccessToken(ctx, tokenSHA)
+		uid, grantScopes := CheckOAuthAccessToken(ctx, tokenSHA)
+
 		if uid != 0 {
 			store.GetData()["IsApiToken"] = true
+			if grantScopes != "" {
+				store.GetData()["ApiTokenScope"] = auth_model.AccessTokenScope(grantScopes)
+			} else {
 				store.GetData()["ApiTokenScope"] = auth_model.AccessTokenScopeAll // fallback to all
 			}
+		}
 		return uid
 	}
 	t, err := auth_model.GetAccessTokenBySHA(ctx, tokenSHA)