Implement /proc/sys/net/ipv4/ip_local_port_range

Speeds up the socket stress tests by a couple orders of magnitude.

PiperOrigin-RevId: 361721050

2 files changed, 81 insertions, 30 deletions

diff --git a/pkg/tcpip/ports/ports.go b/pkg/tcpip/ports/ports.go
index 11dbdbbcf..101872b47 100644
--- a/pkg/tcpip/ports/ports.go
+++ b/pkg/tcpip/ports/ports.go
@@ -16,7 +16,6 @@
 package ports
 
 import (
-	"math"
 	"math/rand"
 	"sync/atomic"
 
@@ -24,16 +23,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip"
 )
 
-const (
-	// FirstEphemeral is the first ephemeral port.
-	FirstEphemeral = 16000
-
-	// numEphemeralPorts it the mnumber of available ephemeral ports to
-	// Netstack.
-	numEphemeralPorts = math.MaxUint16 - FirstEphemeral + 1
-
-	anyIPAddress tcpip.Address = ""
-)
+const anyIPAddress tcpip.Address = ""
 
 type portDescriptor struct {
 	network   tcpip.NetworkProtocolNumber
@@ -83,9 +73,16 @@ func (f Flags) Effective() Flags {
 
 // PortManager manages allocating, reserving and releasing ports.
 type PortManager struct {
+	// mu protects allocatedPorts.
+	// LOCK ORDERING: mu > ephemeralMu.
 	mu             sync.RWMutex
 	allocatedPorts map[portDescriptor]bindAddresses
 
+	// ephemeralMu protects firstEphemeral and numEphemeral.
+	ephemeralMu    sync.RWMutex
+	firstEphemeral uint16
+	numEphemeral   uint16
+
 	// hint is used to pick ports ephemeral ports in a stable order for
 	// a given port offset.
 	//
@@ -322,7 +319,13 @@ func (b bindAddresses) isAvailable(addr tcpip.Address, flags Flags, bindToDevice
 
 // NewPortManager creates new PortManager.
 func NewPortManager() *PortManager {
-	return &PortManager{allocatedPorts: make(map[portDescriptor]bindAddresses)}
+	return &PortManager{
+		allocatedPorts: make(map[portDescriptor]bindAddresses),
+		// Match Linux's default ephemeral range. See:
+		// https://github.com/torvalds/linux/blob/e54937963fa249595824439dc839c948188dea83/net/ipv4/af_inet.c#L1842
+		firstEphemeral: 32768,
+		numEphemeral:   28232,
+	}
 }
 
 // PickEphemeralPort randomly chooses a starting point and iterates over all
@@ -330,13 +333,18 @@ func NewPortManager() *PortManager {
 // is suitable for its needs, and stopping when a port is found or an error
 // occurs.
 func (s *PortManager) PickEphemeralPort(testPort func(p uint16) (bool, tcpip.Error)) (port uint16, err tcpip.Error) {
-	offset := uint32(rand.Int31n(numEphemeralPorts))
-	return s.pickEphemeralPort(offset, numEphemeralPorts, testPort)
+	s.ephemeralMu.RLock()
+	firstEphemeral := s.firstEphemeral
+	numEphemeral := s.numEphemeral
+	s.ephemeralMu.RUnlock()
+
+	offset := uint16(rand.Int31n(int32(numEphemeral)))
+	return pickEphemeralPort(offset, firstEphemeral, numEphemeral, testPort)
 }
 
 // portHint atomically reads and returns the s.hint value.
-func (s *PortManager) portHint() uint32 {
-	return atomic.LoadUint32(&s.hint)
+func (s *PortManager) portHint() uint16 {
+	return uint16(atomic.LoadUint32(&s.hint))
 }
 
 // incPortHint atomically increments s.hint by 1.
@@ -348,8 +356,13 @@ func (s *PortManager) incPortHint() {
 // iterates over all ephemeral ports, allowing the caller to decide whether a
 // given port is suitable for its needs and stopping when a port is found or an
 // error occurs.
-func (s *PortManager) PickEphemeralPortStable(offset uint32, testPort func(p uint16) (bool, tcpip.Error)) (port uint16, err tcpip.Error) {
-	p, err := s.pickEphemeralPort(s.portHint()+offset, numEphemeralPorts, testPort)
+func (s *PortManager) PickEphemeralPortStable(offset uint16, testPort func(p uint16) (bool, tcpip.Error)) (port uint16, err tcpip.Error) {
+	s.ephemeralMu.RLock()
+	firstEphemeral := s.firstEphemeral
+	numEphemeral := s.numEphemeral
+	s.ephemeralMu.RUnlock()
+
+	p, err := pickEphemeralPort(s.portHint()+offset, firstEphemeral, numEphemeral, testPort)
 	if err == nil {
 		s.incPortHint()
 	}
@@ -361,9 +374,9 @@ func (s *PortManager) PickEphemeralPortStable(offset uint32, testPort func(p uin
 // and iterates over the number of ports specified by count and allows the
 // caller to decide whether a given port is suitable for its needs, and stopping
 // when a port is found or an error occurs.
-func (s *PortManager) pickEphemeralPort(offset, count uint32, testPort func(p uint16) (bool, tcpip.Error)) (port uint16, err tcpip.Error) {
-	for i := uint32(0); i < count; i++ {
-		port = uint16(FirstEphemeral + (offset+i)%count)
+func pickEphemeralPort(offset, first, count uint16, testPort func(p uint16) (bool, tcpip.Error)) (port uint16, err tcpip.Error) {
+	for i := uint16(0); i < count; i++ {
+		port = first + (offset+i)%count
 		ok, err := testPort(port)
 		if err != nil {
 			return 0, err
@@ -567,3 +580,24 @@ func (s *PortManager) releasePortLocked(networks []tcpip.NetworkProtocolNumber,
 		}
 	}
 }
+
+// PortRange returns the UDP and TCP inclusive range of ephemeral ports used in
+// both IPv4 and IPv6.
+func (s *PortManager) PortRange() (uint16, uint16) {
+	s.ephemeralMu.RLock()
+	defer s.ephemeralMu.RUnlock()
+	return s.firstEphemeral, s.firstEphemeral + s.numEphemeral - 1
+}
+
+// SetPortRange sets the UDP and TCP IPv4 and IPv6 ephemeral port range
+// (inclusive).
+func (s *PortManager) SetPortRange(start uint16, end uint16) tcpip.Error {
+	if start > end {
+		return &tcpip.ErrInvalidPortRange{}
+	}
+	s.ephemeralMu.Lock()
+	defer s.ephemeralMu.Unlock()
+	s.firstEphemeral = start
+	s.numEphemeral = end - start + 1
+	return nil
+}
diff --git a/pkg/tcpip/ports/ports_test.go b/pkg/tcpip/ports/ports_test.go
index e70fbb72b..6cfac04b1 100644
--- a/pkg/tcpip/ports/ports_test.go
+++ b/pkg/tcpip/ports/ports_test.go
@@ -329,6 +329,7 @@ func TestPortReservation(t *testing.T) {
 			net := []tcpip.NetworkProtocolNumber{fakeNetworkNumber}
 
 			for _, test := range test.actions {
+				first, _ := pm.PortRange()
 				if test.release {
 					pm.ReleasePort(net, fakeTransNumber, test.ip, test.port, test.flags, test.device, test.dest)
 					continue
@@ -337,8 +338,8 @@ func TestPortReservation(t *testing.T) {
 				if diff := cmp.Diff(test.want, err); diff != "" {
 					t.Fatalf("unexpected error from ReservePort(.., .., %s, %d, %+v, %d, %v), (-want, +got):\n%s", test.ip, test.port, test.flags, test.device, test.dest, diff)
 				}
-				if test.port == 0 && (gotPort == 0 || gotPort < FirstEphemeral) {
-					t.Fatalf("ReservePort(.., .., .., 0, ..) = %d, want port number >= %d to be picked", gotPort, FirstEphemeral)
+				if test.port == 0 && (gotPort == 0 || gotPort < first) {
+					t.Fatalf("ReservePort(.., .., .., 0, ..) = %d, want port number >= %d to be picked", gotPort, first)
 				}
 			}
 		})
@@ -346,6 +347,11 @@ func TestPortReservation(t *testing.T) {
 }
 
 func TestPickEphemeralPort(t *testing.T) {
+	const (
+		firstEphemeral    = 32000
+		numEphemeralPorts = 1000
+	)
+
 	for _, test := range []struct {
 		name     string
 		f        func(port uint16) (bool, tcpip.Error)
@@ -369,17 +375,17 @@ func TestPickEphemeralPort(t *testing.T) {
 		{
 			name: "only-port-16042-available",
 			f: func(port uint16) (bool, tcpip.Error) {
-				if port == FirstEphemeral+42 {
+				if port == firstEphemeral+42 {
 					return true, nil
 				}
 				return false, nil
 			},
-			wantPort: FirstEphemeral + 42,
+			wantPort: firstEphemeral + 42,
 		},
 		{
 			name: "only-port-under-16000-available",
 			f: func(port uint16) (bool, tcpip.Error) {
-				if port < FirstEphemeral {
+				if port < firstEphemeral {
 					return true, nil
 				}
 				return false, nil
@@ -389,6 +395,9 @@ func TestPickEphemeralPort(t *testing.T) {
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			pm := NewPortManager()
+			if err := pm.SetPortRange(firstEphemeral, firstEphemeral+numEphemeralPorts); err != nil {
+				t.Fatalf("failed to set ephemeral port range: %s", err)
+			}
 			port, err := pm.PickEphemeralPort(test.f)
 			if diff := cmp.Diff(test.wantErr, err); diff != "" {
 				t.Fatalf("unexpected error from PickEphemeralPort(..), (-want, +got):\n%s", diff)
@@ -401,6 +410,11 @@ func TestPickEphemeralPort(t *testing.T) {
 }
 
 func TestPickEphemeralPortStable(t *testing.T) {
+	const (
+		firstEphemeral    = 32000
+		numEphemeralPorts = 1000
+	)
+
 	for _, test := range []struct {
 		name     string
 		f        func(port uint16) (bool, tcpip.Error)
@@ -424,17 +438,17 @@ func TestPickEphemeralPortStable(t *testing.T) {
 		{
 			name: "only-port-16042-available",
 			f: func(port uint16) (bool, tcpip.Error) {
-				if port == FirstEphemeral+42 {
+				if port == firstEphemeral+42 {
 					return true, nil
 				}
 				return false, nil
 			},
-			wantPort: FirstEphemeral + 42,
+			wantPort: firstEphemeral + 42,
 		},
 		{
 			name: "only-port-under-16000-available",
 			f: func(port uint16) (bool, tcpip.Error) {
-				if port < FirstEphemeral {
+				if port < firstEphemeral {
 					return true, nil
 				}
 				return false, nil
@@ -444,7 +458,10 @@ func TestPickEphemeralPortStable(t *testing.T) {
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			pm := NewPortManager()
-			portOffset := uint32(rand.Int31n(int32(numEphemeralPorts)))
+			if err := pm.SetPortRange(firstEphemeral, firstEphemeral+numEphemeralPorts); err != nil {
+				t.Fatalf("failed to set ephemeral port range: %s", err)
+			}
+			portOffset := uint16(rand.Int31n(int32(numEphemeralPorts)))
 			port, err := pm.PickEphemeralPortStable(portOffset, test.f)
 			if diff := cmp.Diff(test.wantErr, err); diff != "" {
 				t.Fatalf("unexpected error from PickEphemeralPort(..), (-want, +got):\n%s", diff)