Optionally enforce strict TLS SNI + HTTP Host matching, & misc. cleanup

We should look into a way to enable this by default when TLS client auth
is configured for a server
This commit is contained in:
Matthew Holt 2019-06-26 16:03:29 -06:00
parent a524bcfe78
commit 2b22d2e6ea
4 changed files with 49 additions and 14 deletions

View File

@ -13,8 +13,8 @@ import (
// Context is a type which defines the lifetime of modules that
// are loaded and provides access to the parent configuration
// that spawned the modules which are loaded. It should be used
// with care and only wrapped with derivation functions from
// the standard context package if you don't need the Caddy
// with care and wrapped with derivation functions from the
// standard context package only if you don't need the Caddy
// specific features. These contexts are cancelled when the
// lifetime of the modules loaded from it are over.
//

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@ -162,11 +162,11 @@ func (routes RouteList) BuildCompositeRoute(rw http.ResponseWriter, req *http.Re
}
// wrapMiddleware wraps m such that it can be correctly
// appended to a list of middleware. This is necessary
// so that only the last middleware in a loop does not
// become the only middleware of the stack, repeatedly
// executed (i.e. it is necessary to keep a reference
// to this m outside of the scope of a loop)!
// appended to a list of middleware. This separate closure
// is necessary so that only the last middleware in a loop
// does not become the only middleware of the stack,
// repeatedly executed (i.e. it is necessary to keep a
// reference to this m outside of the scope of a loop)!
func wrapMiddleware(m MiddlewareHandler) Middleware {
return func(next HandlerFunc) HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) error {

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@ -7,6 +7,7 @@ import (
"net"
"net/http"
"strconv"
"strings"
"github.com/caddyserver/caddy"
"github.com/caddyserver/caddy/modules/caddytls"
@ -25,6 +26,7 @@ type Server struct {
TLSConnPolicies caddytls.ConnectionPolicies `json:"tls_connection_policies,omitempty"`
AutoHTTPS *AutoHTTPSConfig `json:"automatic_https,omitempty"`
MaxRehandles int `json:"max_rehandles,omitempty"`
StrictSNIHost bool `json:"strict_sni_host,omitempty"` // TODO: see if we can turn this on by default when clientauth is configured
tlsApp *caddytls.TLS
}
@ -47,8 +49,9 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
addHTTPVarsToReplacer(repl, r, w)
// build and execute the main handler chain
stack, w := s.Routes.BuildCompositeRoute(w, r)
err := s.executeCompositeRoute(w, r, stack)
stack, wrappedWriter := s.Routes.BuildCompositeRoute(w, r)
stack = s.wrapPrimaryRoute(stack)
err := s.executeCompositeRoute(wrappedWriter, r, stack)
if err != nil {
// add the raw error value to the request context
// so it can be accessed by error handlers
@ -66,8 +69,8 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
}
if s.Errors != nil && len(s.Errors.Routes) > 0 {
errStack, w := s.Errors.Routes.BuildCompositeRoute(w, r)
err := s.executeCompositeRoute(w, r, errStack)
errStack, wrappedWriter := s.Errors.Routes.BuildCompositeRoute(w, r)
err := s.executeCompositeRoute(wrappedWriter, r, errStack)
if err != nil {
// TODO: what should we do if the error handler has an error?
log.Printf("[ERROR] [%s %s] handling error: %v", r.Method, r.RequestURI, err)
@ -104,6 +107,37 @@ func (s *Server) executeCompositeRoute(w http.ResponseWriter, r *http.Request, s
return err
}
// wrapPrimaryRoute wraps stack (a compiled middleware handler chain)
// in s.enforcementHandler which performs crucial security checks, etc.
func (s *Server) wrapPrimaryRoute(stack Handler) Handler {
return HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
return s.enforcementHandler(w, r, stack)
})
}
// enforcementHandler is an implicit middleware which performs
// standard checks before executing the HTTP middleware chain.
func (s *Server) enforcementHandler(w http.ResponseWriter, r *http.Request, next Handler) error {
// enforce strict host matching, which ensures that the SNI
// value (if any), matches the Host header; essential for
// servers that rely on TLS ClientAuth sharing a listener
// with servers that do not; if not enforced, client could
// bypass by sending benign SNI then restricted Host header
if s.StrictSNIHost && r.TLS != nil {
hostname, _, err := net.SplitHostPort(r.Host)
if err != nil {
hostname = r.Host // OK; probably lacked port
}
if strings.ToLower(r.TLS.ServerName) != strings.ToLower(hostname) {
err := fmt.Errorf("strict host matching: TLS ServerName (%s) and HTTP Host (%s) values differ",
r.TLS.ServerName, hostname)
r.Close = true
return Error(http.StatusForbidden, err)
}
}
return next.ServeHTTP(w, r)
}
func (s *Server) listenersUseAnyPortOtherThan(otherPort int) bool {
for _, lnAddr := range s.Listen {
_, addrs, err := parseListenAddr(lnAddr)

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@ -88,15 +88,16 @@ func (t *TLS) Provision(ctx caddy.Context) error {
// Start activates the TLS module.
func (t *TLS) Start() error {
magic := certmagic.New(t.certCache, certmagic.Config{
Storage: t.ctx.Storage(),
})
// load manual/static (unmanaged) certificates
for _, loader := range t.certificateLoaders {
certs, err := loader.LoadCertificates()
if err != nil {
return fmt.Errorf("loading certificates: %v", err)
}
magic := certmagic.New(t.certCache, certmagic.Config{
Storage: t.ctx.Storage(),
})
for _, cert := range certs {
err := magic.CacheUnmanagedTLSCertificate(cert.Certificate, cert.Tags)
if err != nil {