Set a header read timeout on HTTP servers (#9181)

Newer versions of golangci-lint flag `http.Server` instances that do not
set a `ReadHeaderTimeout` as being vulnerable to "slowloris" attacks,
wherein clients initiate requests that hold connections open
indefinitely.

This change sets a `ReadHeaderTimeout` of 10s. This timeout is fairly
conservative so that clients can eagerly create connections, but is
still constrained enough that these connections won't remain open
indefinitely.

This change also updates kubert to v0.9.1, which instruments a header
read timeout on the policy admission server.

Signed-off-by: Oliver Gould <ver@buoyant.io>

Cargo.lock

@@ -915,9 +915,9 @@ dependencies = [
 
 [[package]]
 name = "kubert"
-version = "0.9.0"
+version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "950ff2a1ad61768b9fe9b3a1eded194feba83c5b4f94252dcff9fa6dae51ce4d"
+checksum = "6b8b65e116e2617ea081f5fcbd31d508243ab0c1c6da3fa2a7177680a61af855"
 dependencies = [
  "ahash",
  "clap",

controller/webhook/server.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/http"
 	"sync/atomic"
+	"time"
 
 	"github.com/linkerd/linkerd2/controller/k8s"
 	pkgk8s "github.com/linkerd/linkerd2/pkg/k8s"
@@ -61,7 +62,8 @@ func NewServer(
 	}()
 
 	server := &http.Server{
-		Addr: addr,
+		Addr:              addr,
+		ReadHeaderTimeout: 10 * time.Second,
 		TLSConfig: &tls.Config{
 			MinVersion: tls.VersionTLS12,
 		},

controller/webhook/server_test.go

@@ -15,7 +15,8 @@ import (
 )
 
 var mockHTTPServer = &http.Server{
-	Addr: ":0",
+	Addr:              ":0",
+	ReadHeaderTimeout: 10 * time.Second,
 	TLSConfig: &tls.Config{
 		MinVersion: tls.VersionTLS12,
 	},

pkg/admin/admin.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"net/http/pprof"
 	"strings"
+	"time"
 
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
@@ -22,8 +23,9 @@ func NewServer(addr string, enablePprof bool) *http.Server {
 	}
 
 	return &http.Server{
-		Addr:    addr,
+		Addr:              addr,
-		Handler: h,
+		Handler:           h,
+		ReadHeaderTimeout: 10 * time.Second,
 	}
 }
 

viz/tap/api/server.go

@@ -10,6 +10,7 @@ import (
 	"net"
 	"net/http"
 	"sync/atomic"
+	"time"
 
 	"github.com/julienschmidt/httprouter"
 	"github.com/linkerd/linkerd2/controller/k8s"
@@ -69,7 +70,8 @@ func NewServer(
 	clientCertPool.AppendCertsFromPEM([]byte(clientCAPem))
 
 	httpServer := &http.Server{
-		Addr: addr,
+		Addr:              addr,
+		ReadHeaderTimeout: 10 * time.Second,
 		TLSConfig: &tls.Config{
 			ClientAuth: tls.VerifyClientCertIfGiven,
 			ClientCAs:  clientCertPool,

web/srv/server.go

@@ -136,10 +136,11 @@ func NewServer(
 	}
 
 	httpServer := &http.Server{
-		Addr:         addr,
+		Addr:              addr,
-		ReadTimeout:  timeout,
+		ReadTimeout:       timeout,
-		WriteTimeout: timeout,
+		ReadHeaderTimeout: timeout,
-		Handler:      wrappedServer,
+		WriteTimeout:      timeout,
+		Handler:           wrappedServer,
 	}
 
 	// webapp routes