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admin: Disable host checking if wildcard interface is specified

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To clarify, listening on wildcard interfaces is NOT the default and
should only be done under certain circumstances and when you know
what you're doing. Emits a warning in the log.

Fixes https://github.com/caddyserver/caddy-docker/issues/71
This commit is contained in:
Matthew Holt 2020-04-16 11:41:32 -06:00
parent 829e36d535
commit f5ccb904a3
No known key found for this signature in database
GPG key ID: 2A349DD577D586A5
2 changed files with 31 additions and 13 deletions
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34
admin.go
View file

@ -60,10 +60,11 @@ type AdminConfig struct {
// default.
EnforceOrigin bool `json:"enforce_origin,omitempty"`
// The list of allowed origins for API requests. Only used if
// `enforce_origin` is true. If not set, the listener address
// will be the default value. If set but empty, no origins will
// be allowed.
// The list of allowed origins/hosts for API requests. Only needed
// if accessing the admin endpoint from a host different from the
// socket's network interface or if `enforce_origin` is true. If not
// set, the listener address will be the default value. If set but
// empty, no origins will be allowed.
Origins []string `json:"origins,omitempty"`
// Options related to configuration management.
@ -99,6 +100,7 @@ func (admin AdminConfig) listenAddr() (NetworkAddress, error) {
func (admin AdminConfig) newAdminHandler(addr NetworkAddress) adminHandler {
muxWrap := adminHandler{
enforceOrigin: admin.EnforceOrigin,
enforceHost: !addr.isWildcardInterface(),
allowedOrigins: admin.allowedOrigins(addr),
mux: http.NewServeMux(),
}
@ -234,12 +236,15 @@ func replaceAdmin(cfg *Config) error {
go adminServer.Serve(ln)
Log().Named("admin").Info(
"admin endpoint started",
Log().Named("admin").Info("admin endpoint started",
zap.String("address", addr.String()),
zap.Bool("enforce_origin", adminConfig.EnforceOrigin),
zap.Strings("origins", handler.allowedOrigins),
)
zap.Strings("origins", handler.allowedOrigins))
if !handler.enforceHost {
Log().Named("admin").Warn("admin endpoint on open interface; host checking disabled",
zap.String("address", addr.String()))
}
return nil
}
@ -271,6 +276,7 @@ type AdminRoute struct {
type adminHandler struct {
enforceOrigin bool
enforceHost bool
allowedOrigins []string
mux *http.ServeMux
}
@ -292,11 +298,13 @@ func (h adminHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// be called more than once per request, for example if a request
// is rewritten (i.e. internal redirect).
func (h adminHandler) serveHTTP(w http.ResponseWriter, r *http.Request) {
// DNS rebinding mitigation
err := h.checkHost(r)
if err != nil {
h.handleError(w, r, err)
return
if h.enforceHost {
// DNS rebinding mitigation
err := h.checkHost(r)
if err != nil {
h.handleError(w, r, err)
return
}
}
if h.enforceOrigin {

10
listeners.go
View file

@ -302,6 +302,16 @@ func (na NetworkAddress) isLoopback() bool {
return false
}
func (na NetworkAddress) isWildcardInterface() bool {
if na.Host == "" {
return true
}
if ip := net.ParseIP(na.Host); ip != nil {
return ip.IsUnspecified()
}
return false
}
func (na NetworkAddress) port() string {
if na.StartPort == na.EndPort {
return strconv.FormatUint(uint64(na.StartPort), 10)