add missing limitedReader

Signed-off-by: Tim Ramlot <42113979+inteon@users.noreply.github.com>

pkg/webhook/admission/http.go

@@ -34,6 +34,9 @@ import (
 var admissionScheme = runtime.NewScheme()
 var admissionCodecs = serializer.NewCodecFactory(admissionScheme)
 
+// based on https://github.com/kubernetes/kubernetes/blob/c28c2009181fcc44c5f6b47e10e62dacf53e4da0/staging/src/k8s.io/pod-security-admission/cmd/webhook/server/server.go
+var maxRequestSize = int64(3 * 1024 * 1024)
+
 func init() {
 	utilruntime.Must(v1.AddToScheme(admissionScheme))
 	utilruntime.Must(v1beta1.AddToScheme(admissionScheme))
@@ -55,12 +58,19 @@ func (wh *Webhook) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	defer r.Body.Close()
-	body, err := io.ReadAll(r.Body)
+	limitedReader := &io.LimitedReader{R: r.Body, N: maxRequestSize}
+	body, err := io.ReadAll(limitedReader)
 	if err != nil {
 		wh.getLogger(nil).Error(err, "unable to read the body from the incoming request")
 		wh.writeResponse(w, Errored(http.StatusBadRequest, err))
 		return
 	}
+	if limitedReader.N <= 0 {
+		err := fmt.Errorf("request entity is too large; limit is %d bytes", maxRequestSize)
+		wh.getLogger(nil).Error(err, "unable to read the body from the incoming request; limit reached")
+		wh.writeResponse(w, Errored(http.StatusBadRequest, err))
+		return
+	}
 
 	// verify the content type is accurate
 	if contentType := r.Header.Get("Content-Type"); contentType != "application/json" {

pkg/webhook/admission/http_test.go

@@ -19,6 +19,7 @@ package admission
 import (
 	"bytes"
 	"context"
+	"crypto/rand"
 	"fmt"
 	"io"
 	"net/http"
@@ -84,6 +85,19 @@ var _ = Describe("Admission Webhooks", func() {
 			Expect(respRecorder.Body.String()).To(Equal(expected))
 		})
 
+		It("should error when given an infinite body", func() {
+			req := &http.Request{
+				Header: http.Header{"Content-Type": []string{"application/json"}},
+				Method: http.MethodPost,
+				Body:   nopCloser{Reader: rand.Reader},
+			}
+
+			expected := `{"response":{"uid":"","allowed":false,"status":{"metadata":{},"message":"request entity is too large; limit is 3145728 bytes","code":400}}}
+`
+			webhook.ServeHTTP(respRecorder, req)
+			Expect(respRecorder.Body.String()).To(Equal(expected))
+		})
+
 		It("should return the response given by the handler with version defaulted to v1", func() {
 			req := &http.Request{
 				Header: http.Header{"Content-Type": []string{"application/json"}},

pkg/webhook/authentication/http.go

@@ -34,6 +34,9 @@ import (
 var authenticationScheme = runtime.NewScheme()
 var authenticationCodecs = serializer.NewCodecFactory(authenticationScheme)
 
+// based on https://github.com/kubernetes/kubernetes/blob/c28c2009181fcc44c5f6b47e10e62dacf53e4da0/staging/src/k8s.io/pod-security-admission/cmd/webhook/server/server.go
+var maxRequestSize = int64(3 * 1024 * 1024)
+
 func init() {
 	utilruntime.Must(authenticationv1.AddToScheme(authenticationScheme))
 	utilruntime.Must(authenticationv1beta1.AddToScheme(authenticationScheme))
@@ -55,12 +58,19 @@ func (wh *Webhook) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	defer r.Body.Close()
-	body, err := io.ReadAll(r.Body)
+	limitedReader := &io.LimitedReader{R: r.Body, N: maxRequestSize}
+	body, err := io.ReadAll(limitedReader)
 	if err != nil {
 		wh.getLogger(nil).Error(err, "unable to read the body from the incoming request")
 		wh.writeResponse(w, Errored(err))
 		return
 	}
+	if limitedReader.N <= 0 {
+		err := fmt.Errorf("request entity is too large; limit is %d bytes", maxRequestSize)
+		wh.getLogger(nil).Error(err, "unable to read the body from the incoming request; limit reached")
+		wh.writeResponse(w, Errored(err))
+		return
+	}
 
 	// verify the content type is accurate
 	if contentType := r.Header.Get("Content-Type"); contentType != "application/json" {

pkg/webhook/authentication/http_test.go

@@ -19,6 +19,7 @@ package authentication
 import (
 	"bytes"
 	"context"
+	"crypto/rand"
 	"fmt"
 	"io"
 	"net/http"
@@ -94,6 +95,19 @@ var _ = Describe("Authentication Webhooks", func() {
 			Expect(respRecorder.Body.String()).To(Equal(expected))
 		})
 
+		It("should error when given an infinite body", func() {
+			req := &http.Request{
+				Header: http.Header{"Content-Type": []string{"application/json"}},
+				Method: http.MethodPost,
+				Body:   nopCloser{Reader: rand.Reader},
+			}
+
+			expected := `{"metadata":{"creationTimestamp":null},"spec":{},"status":{"user":{},"error":"request entity is too large; limit is 3145728 bytes"}}
+`
+			webhook.ServeHTTP(respRecorder, req)
+			Expect(respRecorder.Body.String()).To(Equal(expected))
+		})
+
 		It("should return the response given by the handler with version defaulted to v1", func() {
 			req := &http.Request{
 				Header: http.Header{"Content-Type": []string{"application/json"}},