CSRF Token Implementation for Plugins (#9192)

deleted test config

fix test config

Dont wipe the session token for plugins

Simplified Tokens; Generate CSRF for other sessions

Remove CSRF from Access Token; Remove Getter/Setter from Context

fix removed setter

remove getcsrf helper from plugin api

enforce csrf only for cookie auth

app/login.go

@@ -126,7 +126,7 @@ func (a *App) GetUserForLogin(id, loginId string) (*model.User, *model.AppError)
 
 func (a *App) DoLogin(w http.ResponseWriter, r *http.Request, user *model.User, deviceId string) (*model.Session, *model.AppError) {
 	session := &model.Session{UserId: user.Id, Roles: user.GetRawRoles(), DeviceId: deviceId, IsOAuth: false}
-
+	session.GenerateCSRF()
 	maxAge := *a.Config().ServiceSettings.SessionLengthWebInDays * 60 * 60 * 24
 
 	if len(deviceId) > 0 {

app/oauth.go

@@ -334,6 +334,7 @@ func (a *App) GetOAuthAccessTokenForCodeFlow(clientId, grantType, redirectUri, c
 func (a *App) newSession(appName string, user *model.User) (*model.Session, *model.AppError) {
 	// set new token an session
 	session := &model.Session{UserId: user.Id, Roles: user.Roles, IsOAuth: true}
+	session.GenerateCSRF()
 	session.SetExpireInDays(*a.Config().ServiceSettings.SessionLengthSSOInDays)
 	session.AddProp(model.SESSION_PROP_PLATFORM, appName)
 	session.AddProp(model.SESSION_PROP_OS, "OAuth2")

app/plugin_api.go

@@ -65,6 +65,16 @@ func (api *PluginAPI) UnregisterCommand(teamId, trigger string) error {
 	return nil
 }
 
+func (api *PluginAPI) GetSession(sessionId string) (*model.Session, *model.AppError) {
+	session, err := api.app.GetSessionById(sessionId)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return session, nil
+}
+
 func (api *PluginAPI) GetConfig() *model.Config {
 	return api.app.GetConfig()
 }

app/plugin_requests.go

@@ -8,11 +8,13 @@ import (
 	"path"
 	"strings"
 
+	"bytes"
 	"github.com/gorilla/mux"
 	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/plugin"
 	"github.com/mattermost/mattermost-server/utils"
+	"io/ioutil"
 )
 
 func (a *App) ServePluginRequest(w http.ResponseWriter, r *http.Request) {
@@ -38,22 +40,44 @@ func (a *App) ServePluginRequest(w http.ResponseWriter, r *http.Request) {
 
 func (a *App) servePluginRequest(w http.ResponseWriter, r *http.Request, handler func(*plugin.Context, http.ResponseWriter, *http.Request)) {
 	token := ""
+	context := &plugin.Context{}
+	cookieAuth := false
 
 	authHeader := r.Header.Get(model.HEADER_AUTH)
 	if strings.HasPrefix(strings.ToUpper(authHeader), model.HEADER_BEARER+" ") {
 		token = authHeader[len(model.HEADER_BEARER)+1:]
 	} else if strings.HasPrefix(strings.ToLower(authHeader), model.HEADER_TOKEN+" ") {
 		token = authHeader[len(model.HEADER_TOKEN)+1:]
-	} else if cookie, _ := r.Cookie(model.SESSION_COOKIE_TOKEN); cookie != nil && (r.Method == "GET" || r.Header.Get(model.HEADER_REQUESTED_WITH) == model.HEADER_REQUESTED_WITH_XML) {
+	} else if cookie, _ := r.Cookie(model.SESSION_COOKIE_TOKEN); cookie != nil {
 		token = cookie.Value
+		cookieAuth = true
 	} else {
 		token = r.URL.Query().Get("access_token")
 	}
 
 	r.Header.Del("Mattermost-User-Id")
 	if token != "" {
-		if session, err := a.GetSession(token); session != nil && err == nil {
+		session, err := a.GetSession(token)
+		csrfCheckPassed := true
+
+		if err == nil && cookieAuth && r.Method != "GET" && r.Header.Get(model.HEADER_REQUESTED_WITH) != model.HEADER_REQUESTED_WITH_XML {
+			bodyBytes, _ := ioutil.ReadAll(r.Body)
+			r.Body = ioutil.NopCloser(bytes.NewBuffer(bodyBytes))
+			r.ParseForm()
+			sentToken := r.FormValue("csrf")
+			expectedToken := session.GetCSRF()
+
+			if sentToken != expectedToken {
+				csrfCheckPassed = false
+			}
+
+			// Set Request Body again, since otherwise form values aren't accessible in plugin handler
+			r.Body = ioutil.NopCloser(bytes.NewBuffer(bodyBytes))
+		}
+
+		if session != nil && err == nil && csrfCheckPassed {
 			r.Header.Set("Mattermost-User-Id", session.UserId)
+			context.SessionId = session.Id
 		}
 	}
 
@@ -76,5 +100,5 @@ func (a *App) servePluginRequest(w http.ResponseWriter, r *http.Request, handler
 	r.URL.RawQuery = newQuery.Encode()
 	r.URL.Path = strings.TrimPrefix(r.URL.Path, path.Join(subpath, "plugins", params["plugin_id"]))
 
-	handler(&plugin.Context{}, w, r)
+	handler(context, w, r)
 }