Store endpoints inside multiPortEndpoint in a sorted order

It is required to guarantee the same order of endpoints after save/restore.

PiperOrigin-RevId: 277598665

pkg/tcpip/stack/registration.go

@@ -60,6 +60,9 @@ const (
 // TransportEndpoint is the interface that needs to be implemented by transport
 // protocol (e.g., tcp, udp) endpoints that can handle packets.
 type TransportEndpoint interface {
+	// UniqueID returns an unique ID for this transport endpoint.
+	UniqueID() uint64
+
 	// HandlePacket is called by the stack when new packets arrive to
 	// this transport endpoint.
 	HandlePacket(r *Route, id TransportEndpointID, vv buffer.VectorisedView)

pkg/tcpip/stack/stack.go

@@ -22,6 +22,7 @@ package stack
 import (
 	"encoding/binary"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"golang.org/x/time/rate"
@@ -344,6 +345,13 @@ type ResumableEndpoint interface {
 	Resume(*Stack)
 }
 
+// uniqueIDGenerator is a default unique ID generator.
+type uniqueIDGenerator uint64
+
+func (u *uniqueIDGenerator) UniqueID() uint64 {
+	return atomic.AddUint64((*uint64)(u), 1)
+}
+
 // Stack is a networking stack, with all supported protocols, NICs, and route
 // table.
 type Stack struct {
@@ -411,6 +419,14 @@ type Stack struct {
 	// ndpDisp is the NDP event dispatcher that is used to send the netstack
 	// integrator NDP related events.
 	ndpDisp NDPDispatcher
+
+	// uniqueIDGenerator is a generator of unique identifiers.
+	uniqueIDGenerator UniqueID
+}
+
+// UniqueID is an abstract generator of unique identifiers.
+type UniqueID interface {
+	UniqueID() uint64
 }
 
 // Options contains optional Stack configuration.
@@ -434,6 +450,9 @@ type Options struct {
 	// stack (false).
 	HandleLocal bool
 
+	// UniqueID is an optional generator of unique identifiers.
+	UniqueID UniqueID
+
 	// NDPConfigs is the default NDP configurations used by interfaces.
 	//
 	// By default, NDPConfigs will have a zero value for its
@@ -506,6 +525,10 @@ func New(opts Options) *Stack {
 		clock = &tcpip.StdClock{}
 	}
 
+	if opts.UniqueID == nil {
+		opts.UniqueID = new(uniqueIDGenerator)
+	}
+
 	// Make sure opts.NDPConfigs contains valid values only.
 	opts.NDPConfigs.validate()
 
@@ -524,6 +547,7 @@ func New(opts Options) *Stack {
 		portSeed:             generateRandUint32(),
 		ndpConfigs:           opts.NDPConfigs,
 		autoGenIPv6LinkLocal: opts.AutoGenIPv6LinkLocal,
+		uniqueIDGenerator:    opts.UniqueID,
 		ndpDisp:              opts.NDPDisp,
 	}
 
@@ -551,6 +575,11 @@ func New(opts Options) *Stack {
 	return s
 }
 
+// UniqueID returns a unique identifier.
+func (s *Stack) UniqueID() uint64 {
+	return s.uniqueIDGenerator.UniqueID()
+}
+
 // SetNetworkProtocolOption allows configuring individual protocol level
 // options. This method returns an error if the protocol is not supported or
 // option is not supported by the protocol implementation or the provided value

pkg/tcpip/stack/transport_demuxer.go

@@ -17,6 +17,7 @@ package stack
 import (
 	"fmt"
 	"math/rand"
+	"sort"
 	"sync"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
@@ -310,6 +311,15 @@ func (ep *multiPortEndpoint) singleRegisterEndpoint(t TransportEndpoint, reusePo
 	// endpointsMap. This will allow us to remove endpoint from the array fast.
 	ep.endpointsMap[t] = len(ep.endpointsArr)
 	ep.endpointsArr = append(ep.endpointsArr, t)
+
+	// ep.endpointsArr is sorted by endpoint unique IDs, so that endpoints
+	// can be restored in the same order.
+	sort.Slice(ep.endpointsArr, func(i, j int) bool {
+		return ep.endpointsArr[i].UniqueID() < ep.endpointsArr[j].UniqueID()
+	})
+	for i, e := range ep.endpointsArr {
+		ep.endpointsMap[e] = i
+	}
 	return nil
 }
 

pkg/tcpip/stack/transport_test.go

@@ -43,6 +43,7 @@ type fakeTransportEndpoint struct {
 	proto    *fakeTransportProtocol
 	peerAddr tcpip.Address
 	route    stack.Route
+	uniqueID uint64
 
 	// acceptQueue is non-nil iff bound.
 	acceptQueue []fakeTransportEndpoint
@@ -56,8 +57,8 @@ func (f *fakeTransportEndpoint) Stats() tcpip.EndpointStats {
 	return nil
 }
 
-func newFakeTransportEndpoint(s *stack.Stack, proto *fakeTransportProtocol, netProto tcpip.NetworkProtocolNumber) tcpip.Endpoint {
-	return &fakeTransportEndpoint{stack: s, TransportEndpointInfo: stack.TransportEndpointInfo{NetProto: netProto}, proto: proto}
+func newFakeTransportEndpoint(s *stack.Stack, proto *fakeTransportProtocol, netProto tcpip.NetworkProtocolNumber, uniqueID uint64) tcpip.Endpoint {
+	return &fakeTransportEndpoint{stack: s, TransportEndpointInfo: stack.TransportEndpointInfo{NetProto: netProto}, proto: proto, uniqueID: uniqueID}
 }
 
 func (f *fakeTransportEndpoint) Close() {
@@ -144,6 +145,10 @@ func (f *fakeTransportEndpoint) Connect(addr tcpip.FullAddress) *tcpip.Error {
 	return nil
 }
 
+func (f *fakeTransportEndpoint) UniqueID() uint64 {
+	return f.uniqueID
+}
+
 func (f *fakeTransportEndpoint) ConnectEndpoint(e tcpip.Endpoint) *tcpip.Error {
 	return nil
 }
@@ -251,7 +256,7 @@ func (*fakeTransportProtocol) Number() tcpip.TransportProtocolNumber {
 }
 
 func (f *fakeTransportProtocol) NewEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, _ *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
-	return newFakeTransportEndpoint(stack, f, netProto), nil
+	return newFakeTransportEndpoint(stack, f, netProto, stack.UniqueID()), nil
 }
 
 func (f *fakeTransportProtocol) NewRawEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, _ *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {

pkg/tcpip/transport/icmp/endpoint.go

@@ -58,6 +58,7 @@ type endpoint struct {
 	// immutable.
 	stack       *stack.Stack `state:"manual"`
 	waiterQueue *waiter.Queue
+	uniqueID    uint64
 
 	// The following fields are used to manage the receive queue, and are
 	// protected by rcvMu.
@@ -90,9 +91,15 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProt
 		rcvBufSizeMax: 32 * 1024,
 		sndBufSize:    32 * 1024,
 		state:         stateInitial,
+		uniqueID:      s.UniqueID(),
 	}, nil
 }
 
+// UniqueID implements stack.TransportEndpoint.UniqueID.
+func (e *endpoint) UniqueID() uint64 {
+	return e.uniqueID
+}
+
 // Close puts the endpoint in a closed state and frees all resources
 // associated with it.
 func (e *endpoint) Close() {

pkg/tcpip/transport/tcp/endpoint.go

@@ -287,6 +287,7 @@ type endpoint struct {
 	// change throughout the lifetime of the endpoint.
 	stack       *stack.Stack  `state:"manual"`
 	waiterQueue *waiter.Queue `state:"wait"`
+	uniqueID    uint64
 
 	// lastError represents the last error that the endpoint reported;
 	// access to it is protected by the following mutex.
@@ -504,6 +505,11 @@ type endpoint struct {
 	stats Stats `state:"nosave"`
 }
 
+// UniqueID implements stack.TransportEndpoint.UniqueID.
+func (e *endpoint) UniqueID() uint64 {
+	return e.uniqueID
+}
+
 // calculateAdvertisedMSS calculates the MSS to advertise.
 //
 // If userMSS is non-zero and is not greater than the maximum possible MSS for
@@ -565,6 +571,7 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 			interval: 75 * time.Second,
 			count:    9,
 		},
+		uniqueID: s.UniqueID(),
 	}
 
 	var ss SendBufferSizeOption

pkg/tcpip/transport/udp/endpoint.go

@@ -80,6 +80,7 @@ type endpoint struct {
 	// change throughout the lifetime of the endpoint.
 	stack       *stack.Stack `state:"manual"`
 	waiterQueue *waiter.Queue
+	uniqueID    uint64
 
 	// The following fields are used to manage the receive queue, and are
 	// protected by rcvMu.
@@ -160,9 +161,15 @@ func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, waiterQue
 		rcvBufSizeMax: 32 * 1024,
 		sndBufSize:    32 * 1024,
 		state:         StateInitial,
+		uniqueID:      s.UniqueID(),
 	}
 }
 
+// UniqueID implements stack.TransportEndpoint.UniqueID.
+func (e *endpoint) UniqueID() uint64 {
+	return e.uniqueID
+}
+
 // Close puts the endpoint in a closed state and frees all resources
 // associated with it.
 func (e *endpoint) Close() {

runsc/boot/loader.go

@@ -232,7 +232,7 @@ func New(args Args) (*Loader, error) {
 	// this point. Netns is configured before Run() is called. Netstack is
 	// configured using a control uRPC message. Host network is configured inside
 	// Run().
-	networkStack, err := newEmptyNetworkStack(args.Conf, k)
+	networkStack, err := newEmptyNetworkStack(args.Conf, k, k)
 	if err != nil {
 		return nil, fmt.Errorf("creating network: %v", err)
 	}
@@ -905,7 +905,7 @@ func (l *Loader) WaitExit() kernel.ExitStatus {
 	return l.k.GlobalInit().ExitStatus()
 }
 
-func newEmptyNetworkStack(conf *Config, clock tcpip.Clock) (inet.Stack, error) {
+func newEmptyNetworkStack(conf *Config, clock tcpip.Clock, uniqueID stack.UniqueID) (inet.Stack, error) {
 	switch conf.Network {
 	case NetworkHost:
 		return hostinet.NewStack(), nil
@@ -923,6 +923,7 @@ func newEmptyNetworkStack(conf *Config, clock tcpip.Clock) (inet.Stack, error) {
 			// Enable raw sockets for users with sufficient
 			// privileges.
 			RawFactory: raw.EndpointFactory{},
+			UniqueID:   uniqueID,
 		})}
 
 		// Enable SACK Recovery.

test/syscalls/linux/socket_inet_loopback.cc

@@ -16,6 +16,7 @@
 #include <netinet/in.h>
 #include <poll.h>
 #include <string.h>
+#include <sys/epoll.h>
 #include <sys/socket.h>
 
 #include <atomic>
@@ -516,6 +517,112 @@ TEST_P(SocketInetReusePortTest, UdpPortReuseMultiThread) {
                 EquivalentWithin((kConnectAttempts / kThreadCount), 0.10));
 }
 
+TEST_P(SocketInetReusePortTest, UdpPortReuseMultiThreadShort) {
+  auto const& param = GetParam();
+
+  TestAddress const& listener = param.listener;
+  TestAddress const& connector = param.connector;
+  sockaddr_storage listen_addr = listener.addr;
+  sockaddr_storage conn_addr = connector.addr;
+  constexpr int kThreadCount = 3;
+
+  // TODO(b/141211329): endpointsByNic.seed has to be saved/restored.
+  const DisableSave ds141211329;
+
+  // Create listening sockets.
+  FileDescriptor listener_fds[kThreadCount];
+  for (int i = 0; i < kThreadCount; i++) {
+    listener_fds[i] =
+        ASSERT_NO_ERRNO_AND_VALUE(Socket(listener.family(), SOCK_DGRAM, 0));
+    int fd = listener_fds[i].get();
+
+    ASSERT_THAT(setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &kSockOptOn,
+                           sizeof(kSockOptOn)),
+                SyscallSucceeds());
+    ASSERT_THAT(
+        bind(fd, reinterpret_cast<sockaddr*>(&listen_addr), listener.addr_len),
+        SyscallSucceeds());
+
+    // On the first bind we need to determine which port was bound.
+    if (i != 0) {
+      continue;
+    }
+
+    // Get the port bound by the listening socket.
+    socklen_t addrlen = listener.addr_len;
+    ASSERT_THAT(
+        getsockname(listener_fds[0].get(),
+                    reinterpret_cast<sockaddr*>(&listen_addr), &addrlen),
+        SyscallSucceeds());
+    uint16_t const port =
+        ASSERT_NO_ERRNO_AND_VALUE(AddrPort(listener.family(), listen_addr));
+    ASSERT_NO_ERRNO(SetAddrPort(listener.family(), &listen_addr, port));
+    ASSERT_NO_ERRNO(SetAddrPort(connector.family(), &conn_addr, port));
+  }
+
+  constexpr int kConnectAttempts = 10;
+  FileDescriptor client_fds[kConnectAttempts];
+
+  // Do the first run without save/restore.
+  DisableSave ds;
+  for (int i = 0; i < kConnectAttempts; i++) {
+    client_fds[i] =
+        ASSERT_NO_ERRNO_AND_VALUE(Socket(connector.family(), SOCK_DGRAM, 0));
+    EXPECT_THAT(RetryEINTR(sendto)(client_fds[i].get(), &i, sizeof(i), 0,
+                                   reinterpret_cast<sockaddr*>(&conn_addr),
+                                   connector.addr_len),
+                SyscallSucceedsWithValue(sizeof(i)));
+  }
+  ds.reset();
+
+  // Check that a mapping of client and server sockets has
+  // not been change after save/restore.
+  for (int i = 0; i < kConnectAttempts; i++) {
+    EXPECT_THAT(RetryEINTR(sendto)(client_fds[i].get(), &i, sizeof(i), 0,
+                                   reinterpret_cast<sockaddr*>(&conn_addr),
+                                   connector.addr_len),
+                SyscallSucceedsWithValue(sizeof(i)));
+  }
+
+  int epollfd;
+  ASSERT_THAT(epollfd = epoll_create1(0), SyscallSucceeds());
+
+  for (int i = 0; i < kThreadCount; i++) {
+    int fd = listener_fds[i].get();
+    struct epoll_event ev;
+    ev.data.fd = fd;
+    ev.events = EPOLLIN;
+    ASSERT_THAT(epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev), SyscallSucceeds());
+  }
+
+  std::map<uint16_t, int> portToFD;
+
+  for (int i = 0; i < kConnectAttempts * 2; i++) {
+    struct sockaddr_storage addr = {};
+    socklen_t addrlen = sizeof(addr);
+    struct epoll_event ev;
+    int data, fd;
+
+    ASSERT_THAT(epoll_wait(epollfd, &ev, 1, -1), SyscallSucceedsWithValue(1));
+
+    fd = ev.data.fd;
+    EXPECT_THAT(RetryEINTR(recvfrom)(fd, &data, sizeof(data), 0,
+                                     reinterpret_cast<struct sockaddr*>(&addr),
+                                     &addrlen),
+                SyscallSucceedsWithValue(sizeof(data)));
+    uint16_t const port =
+        ASSERT_NO_ERRNO_AND_VALUE(AddrPort(connector.family(), addr));
+    auto prev_port = portToFD.find(port);
+    // Check that all packets from one client have been delivered to the same
+    // server socket.
+    if (prev_port == portToFD.end()) {
+      portToFD[port] = ev.data.fd;
+    } else {
+      EXPECT_EQ(portToFD[port], ev.data.fd);
+    }
+  }
+}
+
 INSTANTIATE_TEST_SUITE_P(
     All, SocketInetReusePortTest,
     ::testing::Values(