Make UDP traceroute work.

Adds support to generate Port Unreachable messages for UDP
datagrams received on a port for which there is no valid
endpoint.

Fixes #703

PiperOrigin-RevId: 267034418

7 files changed, 142 insertions, 3 deletions

diff --git a/pkg/tcpip/stack/BUILD b/pkg/tcpip/stack/BUILD
index b692c60ce..788de3dfe 100644
--- a/pkg/tcpip/stack/BUILD
+++ b/pkg/tcpip/stack/BUILD
@@ -18,6 +18,7 @@ go_template_instance(
 go_library(
     name = "stack",
     srcs = [
+        "icmp_rate_limit.go",
         "linkaddrcache.go",
         "linkaddrentry_list.go",
         "nic.go",
@@ -42,6 +43,7 @@ go_library(
         "//pkg/tcpip/ports",
         "//pkg/tcpip/seqnum",
         "//pkg/waiter",
+        "@org_golang_x_time//rate:go_default_library",
     ],
 )
 
diff --git a/pkg/tcpip/stack/icmp_rate_limit.go b/pkg/tcpip/stack/icmp_rate_limit.go
new file mode 100644
index 000000000..f8156be47
--- /dev/null
+++ b/pkg/tcpip/stack/icmp_rate_limit.go
@@ -0,0 +1,86 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stack
+
+import (
+	"sync"
+
+	"golang.org/x/time/rate"
+)
+
+const (
+	// icmpLimit is the default maximum number of ICMP messages permitted by this
+	// rate limiter.
+	icmpLimit = 1000
+
+	// icmpBurst is the default number of ICMP messages that can be sent in a single
+	// burst.
+	icmpBurst = 50
+)
+
+// ICMPRateLimiter is a global rate limiter that controls the generation of
+// ICMP messages generated by the stack.
+type ICMPRateLimiter struct {
+	mu sync.RWMutex
+	l  *rate.Limiter
+}
+
+// NewICMPRateLimiter returns a global rate limiter for controlling the rate
+// at which ICMP messages are generated by the stack.
+func NewICMPRateLimiter() *ICMPRateLimiter {
+	return &ICMPRateLimiter{l: rate.NewLimiter(icmpLimit, icmpBurst)}
+}
+
+// Allow returns true if we are allowed to send at least 1 message at the
+// moment.
+func (i *ICMPRateLimiter) Allow() bool {
+	i.mu.RLock()
+	allow := i.l.Allow()
+	i.mu.RUnlock()
+	return allow
+}
+
+// Limit returns the maximum number of ICMP messages that can be sent in one
+// second.
+func (i *ICMPRateLimiter) Limit() rate.Limit {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+	return i.l.Limit()
+}
+
+// SetLimit sets the maximum number of ICMP messages that can be sent in one
+// second.
+func (i *ICMPRateLimiter) SetLimit(newLimit rate.Limit) {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+	i.l.SetLimit(newLimit)
+}
+
+// Burst returns how many ICMP messages can be sent at any single instant.
+func (i *ICMPRateLimiter) Burst() int {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+	return i.l.Burst()
+}
+
+// SetBurst sets the maximum number of ICMP messages allowed at any single
+// instant.
+//
+// NOTE: Changing Burst causes the underlying rate limiter to be recreated.
+func (i *ICMPRateLimiter) SetBurst(burst int) {
+	i.mu.Lock()
+	i.l = rate.NewLimiter(i.l.Limit(), burst)
+	i.mu.Unlock()
+}
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index f947b55db..ae56e0ffd 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -679,7 +679,7 @@ func (n *NIC) DeliverTransportPacket(r *Route, protocol tcpip.TransportProtocolN
 
 	// We could not find an appropriate destination for this packet, so
 	// deliver it to the global handler.
-	if !transProto.HandleUnknownDestinationPacket(r, id, vv) {
+	if !transProto.HandleUnknownDestinationPacket(r, id, netHeader, vv) {
 		n.stack.stats.MalformedRcvdPackets.Increment()
 	}
 }
@@ -720,6 +720,11 @@ func (n *NIC) ID() tcpip.NICID {
 	return n.id
 }
 
+// Stack returns the instance of the Stack that owns this NIC.
+func (n *NIC) Stack() *Stack {
+	return n.stack
+}
+
 type networkEndpointKind int32
 
 const (
@@ -823,3 +828,8 @@ func (r *referencedNetworkEndpoint) tryIncRef() bool {
 		}
 	}
 }
+
+// stack returns the Stack instance that owns the underlying endpoint.
+func (r *referencedNetworkEndpoint) stack() *Stack {
+	return r.nic.stack
+}
diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go
index 2037eef9f..67b70b2ee 100644
--- a/pkg/tcpip/stack/registration.go
+++ b/pkg/tcpip/stack/registration.go
@@ -109,7 +109,7 @@ type TransportProtocol interface {
 	//
 	// The return value indicates whether the packet was well-formed (for
 	// stats purposes only).
-	HandleUnknownDestinationPacket(r *Route, id TransportEndpointID, vv buffer.VectorisedView) bool
+	HandleUnknownDestinationPacket(r *Route, id TransportEndpointID, netHeader buffer.View, vv buffer.VectorisedView) bool
 
 	// SetOption allows enabling/disabling protocol specific features.
 	// SetOption returns an error if the option is not supported or the
diff --git a/pkg/tcpip/stack/route.go b/pkg/tcpip/stack/route.go
index e52cdd674..5c8b7977a 100644
--- a/pkg/tcpip/stack/route.go
+++ b/pkg/tcpip/stack/route.go
@@ -217,3 +217,8 @@ func (r *Route) MakeLoopedRoute() Route {
 	}
 	return l
 }
+
+// Stack returns the instance of the Stack that owns this route.
+func (r *Route) Stack() *Stack {
+	return r.ref.stack()
+}
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index d69162ba1..1d5e84a8b 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -28,6 +28,7 @@ import (
 	"sync"
 	"time"
 
+	"golang.org/x/time/rate"
 	"gvisor.dev/gvisor/pkg/sleep"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -389,6 +390,10 @@ type Stack struct {
 	// resumableEndpoints is a list of endpoints that need to be resumed if the
 	// stack is being restored.
 	resumableEndpoints []ResumableEndpoint
+
+	// icmpRateLimiter is a global rate limiter for all ICMP messages generated
+	// by the stack.
+	icmpRateLimiter *ICMPRateLimiter
 }
 
 // Options contains optional Stack configuration.
@@ -434,6 +439,7 @@ func New(network []string, transport []string, opts Options) *Stack {
 		stats:              opts.Stats.FillIn(),
 		handleLocal:        opts.HandleLocal,
 		raw:                opts.Raw,
+		icmpRateLimiter:    NewICMPRateLimiter(),
 	}
 
 	// Add specified network protocols.
@@ -1215,3 +1221,33 @@ func (s *Stack) IPTables() iptables.IPTables {
 func (s *Stack) SetIPTables(ipt iptables.IPTables) {
 	s.tables = ipt
 }
+
+// ICMPLimit returns the maximum number of ICMP messages that can be sent
+// in one second.
+func (s *Stack) ICMPLimit() rate.Limit {
+	return s.icmpRateLimiter.Limit()
+}
+
+// SetICMPLimit sets the maximum number of ICMP messages that be sent
+// in one second.
+func (s *Stack) SetICMPLimit(newLimit rate.Limit) {
+	s.icmpRateLimiter.SetLimit(newLimit)
+}
+
+// ICMPBurst returns the maximum number of ICMP messages that can be sent
+// in a single burst.
+func (s *Stack) ICMPBurst() int {
+	return s.icmpRateLimiter.Burst()
+}
+
+// SetICMPBurst sets the maximum number of ICMP messages that can be sent
+// in a single burst.
+func (s *Stack) SetICMPBurst(burst int) {
+	s.icmpRateLimiter.SetBurst(burst)
+}
+
+// AllowICMPMessage returns true if we the rate limiter allows at least one
+// ICMP message to be sent at this instant.
+func (s *Stack) AllowICMPMessage() bool {
+	return s.icmpRateLimiter.Allow()
+}
diff --git a/pkg/tcpip/stack/transport_test.go b/pkg/tcpip/stack/transport_test.go
index 5335897f5..ca185279e 100644
--- a/pkg/tcpip/stack/transport_test.go
+++ b/pkg/tcpip/stack/transport_test.go
@@ -251,7 +251,7 @@ func (*fakeTransportProtocol) ParsePorts(buffer.View) (src, dst uint16, err *tcp
 	return 0, 0, nil
 }
 
-func (*fakeTransportProtocol) HandleUnknownDestinationPacket(*stack.Route, stack.TransportEndpointID, buffer.VectorisedView) bool {
+func (*fakeTransportProtocol) HandleUnknownDestinationPacket(*stack.Route, stack.TransportEndpointID, buffer.View, buffer.VectorisedView) bool {
 	return true
 }