Do not include secrets in the config hash

server/config.go

@@ -130,9 +130,9 @@ type Config struct {
 	AuthFile                             string
 	AuthStartupQueries                   string
 	AuthDefault                          user.Permission
-	AuthUsers                            []*user.User
+	AuthUsers                            []*user.User `hash:"-"`
 	AuthAccess                           map[string][]*user.Grant
-	AuthTokens                           map[string][]*user.Token
+	AuthTokens                           map[string][]*user.Token `hash:"-"`
 	AuthBcryptCost                       int
 	AuthStatsQueueWriterInterval         time.Duration
 	AuthAccessCacheEnabled               bool          // Enables the in-memory ACL cache (high volume servers only)
@@ -153,17 +153,17 @@ type Config struct {
 	FirebasePollInterval                 time.Duration
 	FirebaseQuotaExceededPenaltyDuration time.Duration
 	UpstreamBaseURL                      string
-	UpstreamAccessToken                  string
+	UpstreamAccessToken                  string `hash:"-"`
 	SMTPSenderAddr                       string
 	SMTPSenderUser                       string
-	SMTPSenderPass                       string
+	SMTPSenderPass                       string `hash:"-"`
 	SMTPSenderFrom                       string
 	SMTPSenderVerify                     bool
 	SMTPServerListen                     string
 	SMTPServerDomain                     string
 	SMTPServerAddrPrefix                 string
 	TwilioAccount                        string
-	TwilioAuthToken                      string
+	TwilioAuthToken                      string `hash:"-"`
 	TwilioPhoneNumber                    string
 	TwilioCallsBaseURL                   string
 	TwilioVerifyBaseURL                  string
@@ -198,8 +198,8 @@ type Config struct {
 	BehindProxy                          bool           // If true, the server will trust the proxy client IP header to determine the client IP address (IPv4 and IPv6 supported)
 	ProxyForwardedHeader                 string         // The header field to read the real/client IP address from, if BehindProxy is true, defaults to "X-Forwarded-For" (IPv4 and IPv6 supported)
 	ProxyTrustedPrefixes                 []netip.Prefix // List of trusted proxy networks (IPv4 or IPv6) that will be stripped from the Forwarded header if BehindProxy is true
-	StripeSecretKey                      string
-	StripeWebhookKey                     string
+	StripeSecretKey                      string         `hash:"-"`
+	StripeWebhookKey                     string         `hash:"-"`
 	StripePriceCacheDuration             time.Duration
 	BillingContact                       string
 	EnableSignup                         bool // Enable creation of accounts via API and UI
@@ -208,7 +208,7 @@ type Config struct {
 	EnableReservations                   bool // Allow users with role "user" to own/reserve topics
 	EnableMetrics                        bool
 	AccessControlAllowOrigin             string // CORS header field to restrict access from web clients
-	WebPushPrivateKey                    string
+	WebPushPrivateKey                    string `hash:"-"`
 	WebPushPublicKey                     string
 	WebPushFile                          string
 	WebPushEmailAddress                  string
@@ -342,6 +342,10 @@ func (c *Config) Hash() string {
 	for i := 0; i < v.NumField(); i++ {
 		field := v.Field(i)
 		fieldName := t.Field(i).Name
+		// Secrets must not feed the hash
+		if t.Field(i).Tag.Get("hash") == "-" {
+			continue
+		}
 		// Try to marshal the field and skip if it fails (e.g. *template.Template, netip.Prefix)
 		if b, err := json.Marshal(field.Interface()); err == nil {
 			result += fmt.Sprintf("%s:%s|", fieldName, string(b))

server/config_test.go

@@ -3,6 +3,7 @@ package server_test
 import (
 	"github.com/stretchr/testify/assert"
 	"heckel.io/ntfy/v2/server"
+	"heckel.io/ntfy/v2/user"
 	"testing"
 )
 
@@ -11,3 +12,24 @@ func TestConfig_New(t *testing.T) {
 	assert.Equal(t, ":80", c.ListenHTTP)
 	assert.Equal(t, server.DefaultKeepaliveInterval, c.KeepaliveInterval)
 }
+
+func TestConfig_HashExcludesSecrets(t *testing.T) {
+	// The config hash is served to browsers (ConfigHash, for webapp change detection), so
+	// secret material must not feed it: a weak secret would otherwise be offline-brute-forceable
+	// against a publicly visible hash.
+	conf1 := server.NewConfig()
+	conf2 := server.NewConfig()
+	conf2.StripeSecretKey = "sk_live_topsecret"
+	conf2.StripeWebhookKey = "whsec_topsecret"
+	conf2.TwilioAuthToken = "twilio-auth-token"
+	conf2.UpstreamAccessToken = "tk_upstream"
+	conf2.WebPushPrivateKey = "web-push-private-key"
+	conf2.SMTPSenderPass = "hunter2"
+	conf2.AuthUsers = []*user.User{{Name: "phil", Hash: "$2a$10$somebcrypthash"}}
+	conf2.AuthTokens = map[string][]*user.Token{"phil": {{Value: "tk_secrettoken"}}}
+	assert.Equal(t, conf1.Hash(), conf2.Hash())
+	// Non-secret fields must still change the hash
+	conf3 := server.NewConfig()
+	conf3.BaseURL = "https://ntfy.example.com"
+	assert.NotEqual(t, conf1.Hash(), conf3.Hash())
+}