fix: enable iframe use on http://localhost (#7152)

* fix: enable iframe use on http://localhost

* docs(iframe): add info about cookies

* improve comments

docs/docs/guides/solution-scenarios/configurations.mdx

@@ -105,7 +105,7 @@ Go to the "Advanced" section, per default login with phone number should be allo
 ## Embedding ZITADEL in an iFrame
 
 To maximise the security during login and in the Console UI, ZITADEL follows security best practices by setting a
-Content-Security-Policy (CSP) and X-Frame-Options:
+Content-Security-Policy (CSP), X-Frame-Options and cookies with SameSite Lax:
 
 ```
 Content-Security-Policy: frame-ancestors 'none'
@@ -136,7 +136,13 @@ This will change the CSP to the following:
 Content-Security-Policy: frame-ancestors https://custom-domain.com
 ```
 
-and remove the X-Frame-Options header.
+remove the X-Frame-Options header and change the SameSite to `None`.
+
+:::note
+Please note, that SameSite None requires the cookie to be flagged `secure`, which means it must be sent over TLS (HTTPS) or localhost.
+This also means that domains other than localhost must use TLS for this option to work.
+This is due to browser restrictions: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie#none
+:::
 
 ### Disable Multi-factor (MFA) Prompt
 

internal/api/http/cookie.go

@@ -10,10 +10,12 @@ import (
 )
 
 const (
-	prefixSecure = "__Secure-"
-	prefixHost   = "__Host-"
+	PrefixSecure cookiePrefix = "__Secure-"
+	PrefixHost   cookiePrefix = "__Host-"
 )
 
+type cookiePrefix string
+
 type CookieHandler struct {
 	securecookie *securecookie.SecureCookie
 	secureOnly   bool
@@ -21,6 +23,7 @@ type CookieHandler struct {
 	sameSite     http.SameSite
 	path         string
 	maxAge       int
+	prefix       cookiePrefix
 }
 
 func NewCookieHandler(opts ...CookieHandlerOpt) *CookieHandler {
@@ -78,14 +81,17 @@ func WithMaxAge(maxAge int) CookieHandlerOpt {
 	}
 }
 
-func SetCookiePrefix(name, domain, path string, secureOnly bool) string {
+func WithPrefix(prefix cookiePrefix) CookieHandlerOpt {
+	return func(c *CookieHandler) {
+		c.prefix = prefix
+	}
+}
+
+func SetCookiePrefix(name string, secureOnly bool, prefix cookiePrefix) string {
 	if !secureOnly {
 		return name
 	}
-	if domain != "" || path != "/" {
-		return prefixSecure + name
-	}
-	return prefixHost + name
+	return string(prefix) + name
 }
 
 func (c *CookieHandler) GetCookieValue(r *http.Request, name string) (string, error) {
@@ -97,7 +103,7 @@ func (c *CookieHandler) GetCookieValue(r *http.Request, name string) (string, er
 }
 
 func (c *CookieHandler) GetEncryptedCookieValue(r *http.Request, name string, value interface{}) error {
-	cookie, err := r.Cookie(SetCookiePrefix(name, r.Host, c.path, c.secureOnly))
+	cookie, err := r.Cookie(SetCookiePrefix(name, c.secureOnly, c.prefix))
 	if err != nil {
 		return err
 	}
@@ -131,19 +137,24 @@ func (c *CookieHandler) DeleteCookie(w http.ResponseWriter, name string) {
 	c.httpSet(w, name, "", "", -1)
 }
 
-func (c *CookieHandler) httpSet(w http.ResponseWriter, name, domain, value string, maxage int) {
-	c.httpSetWithSameSite(w, name, domain, value, maxage, c.sameSite)
+func (c *CookieHandler) httpSet(w http.ResponseWriter, name, domain, value string, maxAge int) {
+	c.httpSetWithSameSite(w, name, domain, value, maxAge, c.sameSite)
 }
 
-func (c *CookieHandler) httpSetWithSameSite(w http.ResponseWriter, name, domain, value string, maxage int, sameSite http.SameSite) {
+func (c *CookieHandler) httpSetWithSameSite(w http.ResponseWriter, name, host, value string, maxAge int, sameSite http.SameSite) {
+	domain := strings.Split(host, ":")[0]
+	// same site none requires the secure flag, so we'll set it even if the cookie is set on non-TLS for localhost
+	secure := c.secureOnly || (sameSite == http.SameSiteNoneMode && domain == "localhost")
+	// prefix the cookie for secure cookies (TLS only, therefore not for samesite none on http://localhost)
+	prefixedName := SetCookiePrefix(name, c.secureOnly, c.prefix)
 	http.SetCookie(w, &http.Cookie{
-		Name:     SetCookiePrefix(name, domain, c.path, c.secureOnly),
+		Name:     prefixedName,
 		Value:    value,
-		Domain:   strings.Split(domain, ":")[0],
+		Domain:   domain,
 		Path:     c.path,
-		MaxAge:   maxage,
+		MaxAge:   maxAge,
 		HttpOnly: c.httpOnly,
-		Secure:   c.secureOnly,
+		Secure:   secure,
 		SameSite: sameSite,
 	})
 	varyValues := w.Header().Values("vary")

internal/api/http/middleware/user_agent_cookie.go

@@ -46,6 +46,7 @@ func NewUserAgentHandler(config *UserAgentCookieConfig, cookieKey []byte, idGene
 	opts := []http_utils.CookieHandlerOpt{
 		http_utils.WithEncryption(cookieKey, cookieKey),
 		http_utils.WithMaxAge(int(config.MaxAge.Seconds())),
+		http_utils.WithPrefix(http_utils.PrefixSecure),
 	}
 	if !externalSecure {
 		opts = append(opts, http_utils.WithUnsecure())

internal/api/ui/login/login.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/gorilla/csrf"
 	"github.com/gorilla/mux"
+
 	"github.com/zitadel/zitadel/feature"
 	"github.com/zitadel/zitadel/internal/api/authz"
 	http_utils "github.com/zitadel/zitadel/internal/api/http"
@@ -122,13 +123,21 @@ func createCSRFInterceptor(cookieName string, csrfCookieKey []byte, externalSecu
 				handler.ServeHTTP(w, r)
 				return
 			}
+			// by default we use SameSite Lax and the externalSecure (TLS) for the secure flag
 			sameSiteMode := csrf.SameSiteLaxMode
-			if len(authz.GetInstance(r.Context()).SecurityPolicyAllowedOrigins()) > 0 {
+			secureOnly := externalSecure
+			instance := authz.GetInstance(r.Context())
+			// in case of `allow iframe`...
+			if len(instance.SecurityPolicyAllowedOrigins()) > 0 {
+				// ... we need to change to SameSite none ...
 				sameSiteMode = csrf.SameSiteNoneMode
+				// ... and since SameSite none requires the secure flag, we'll set it for TLS and for localhost
+				// (regardless of the TLS / externalSecure settings)
+				secureOnly = externalSecure || instance.RequestedDomain() == "localhost"
 			}
 			csrf.Protect(csrfCookieKey,
-				csrf.Secure(externalSecure),
-				csrf.CookieName(http_utils.SetCookiePrefix(cookieName, "", path, externalSecure)),
+				csrf.Secure(secureOnly),
+				csrf.CookieName(http_utils.SetCookiePrefix(cookieName, externalSecure, http_utils.PrefixHost)),
 				csrf.Path(path),
 				csrf.ErrorHandler(errorHandler),
 				csrf.SameSite(sameSiteMode),