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admin: Disable host checking if wildcard interface is specified 

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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24
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
}
@ -292,12 +298,14 @@ 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) {
if h.enforceHost {
// DNS rebinding mitigation
err := h.checkHost(r)
if err != nil {
h.handleError(w, r, err)
return
}
}
if h.enforceOrigin {
// cross-site mitigation

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)