Disable HTTP/2 for webhoook by updating Knative

This disables HTTP/2 for webhook by updating to PR knative/pkg#2875
It fixes CVE-2023-44487.

go.mod

@@ -33,7 +33,7 @@ require (
 	k8s.io/klog/v2 v2.100.1
 	k8s.io/kube-openapi v0.0.0-20230515203736-54b630e78af5
 	knative.dev/eventing v0.30.1-0.20220407170245-58865afba92c
-	knative.dev/pkg v0.0.0-20230418073056-dfad48eaa5d0
+	knative.dev/pkg v0.0.0-20231023160942-0c39ce4b3a7f
 	knative.dev/serving v0.30.1-0.20220402124840-21c05dc9d9a4
 	sigs.k8s.io/yaml v1.3.0
 )

go.sum

@@ -2383,8 +2383,8 @@ knative.dev/networking v0.0.0-20220404212543-dde40b019aff/go.mod h1:5mOmDZAOLZ4s
 knative.dev/pkg v0.0.0-20220318133418-7f16595277b2/go.mod h1:nKJ2L4o7or3j58eqMK843kbIM0SiYnAXXsisfEQECS8=
 knative.dev/pkg v0.0.0-20220318185521-e6e3cf03d765/go.mod h1:nKJ2L4o7or3j58eqMK843kbIM0SiYnAXXsisfEQECS8=
 knative.dev/pkg v0.0.0-20220325200448-1f7514acd0c2/go.mod h1:5xt0nzCwxvQ2N4w71smY7pYm5nVrQ8qnRsMinSLVpio=
-knative.dev/pkg v0.0.0-20230418073056-dfad48eaa5d0 h1:EFQcoUo8I4bc+U3y6tR1B3ONYZSHWUdAfI7Vh7dae8g=
-knative.dev/pkg v0.0.0-20230418073056-dfad48eaa5d0/go.mod h1:2qWPP9Gjh9Q7ETti+WRHnBnGCSCq+6q7m3p/nmUQviE=
+knative.dev/pkg v0.0.0-20231023160942-0c39ce4b3a7f h1:XCH1qZqW1riR8cjhMGjewxQXlWPrfgxeUorBjpC6lE4=
+knative.dev/pkg v0.0.0-20231023160942-0c39ce4b3a7f/go.mod h1:ZRgzFBFmdBsARm6+Pkr9WRG8bXys8rYq64ELfLG6+9w=
 knative.dev/reconciler-test v0.0.0-20220328072550-7d32310c9b3a/go.mod h1:wlz1lGyn5fjJYL5PTSL/SOI4xgVpU+q6D4eaa19NsDA=
 knative.dev/serving v0.30.1-0.20220402124840-21c05dc9d9a4 h1:iRFWsFKsA5ddhi+eKZVJdf8gPBomTfjIyRAKk9Uh7Ko=
 knative.dev/serving v0.30.1-0.20220402124840-21c05dc9d9a4/go.mod h1:TIKeQ1Dvn/wfmgth1fpBeYi1Qf0TPlulnwUDwOdZN50=

vendor/knative.dev/pkg/webhook/webhook.go

@@ -67,6 +67,17 @@ type Options struct {
 	// GracePeriod is how long to wait after failing readiness probes
 	// before shutting down.
 	GracePeriod time.Duration
+
+	// EnableHTTP2 enables HTTP2 for webhooks.
+	// Mitigate CVE-2023-44487 by disabling HTTP2 by default until the Go
+	// standard library and golang.org/x/net are fully fixed.
+	// Right now, it is possible for authenticated and unauthenticated users to
+	// hold open HTTP2 connections and consume huge amounts of memory.
+	// See:
+	// * https://github.com/kubernetes/kubernetes/pull/121120
+	// * https://github.com/kubernetes/kubernetes/issues/121197
+	// * https://github.com/golang/go/issues/63417#issuecomment-1758858612
+	EnableHTTP2 bool
 }
 
 // Operation is the verb being operated on
@@ -219,11 +230,18 @@ func (wh *Webhook) Run(stop <-chan struct{}) error {
 		QuietPeriod: wh.Options.GracePeriod,
 	}
 
+	// If TLSNextProto is not nil, HTTP/2 support is not enabled automatically.
+	nextProto := map[string]func(*http.Server, *tls.Conn, http.Handler){}
+	if wh.Options.EnableHTTP2 {
+		nextProto = nil
+	}
+
 	server := &http.Server{
 		Handler:           drainer,
 		Addr:              fmt.Sprint(":", wh.Options.Port),
 		TLSConfig:         wh.tlsConfig,
 		ReadHeaderTimeout: time.Minute, //https://medium.com/a-journey-with-go/go-understand-and-mitigate-slowloris-attack-711c1b1403f6
+		TLSNextProto:      nextProto,
 	}
 
 	eg, ctx := errgroup.WithContext(ctx)

vendor/modules.txt

@@ -1233,7 +1233,7 @@ knative.dev/eventing/pkg/reconciler/source
 ## explicit; go 1.16
 knative.dev/networking/pkg/apis/networking
 knative.dev/networking/pkg/apis/networking/v1alpha1
-# knative.dev/pkg v0.0.0-20230418073056-dfad48eaa5d0
+# knative.dev/pkg v0.0.0-20231023160942-0c39ce4b3a7f
 ## explicit; go 1.18
 knative.dev/pkg/apis
 knative.dev/pkg/apis/duck