Merge 216da0b7 (automated)

1 files changed, 887 insertions, 0 deletions

diff --git a/pkg/sentry/socket/rpcinet/socket.go b/pkg/sentry/socket/rpcinet/socket.go
new file mode 100644
index 000000000..55e0b6665
--- /dev/null
+++ b/pkg/sentry/socket/rpcinet/socket.go
@@ -0,0 +1,887 @@
+// 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 rpcinet
+
+import (
+	"sync/atomic"
+	"syscall"
+	"time"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/binary"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/kdefs"
+	ktime "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/socket"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/conn"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/notifier"
+	pb "gvisor.googlesource.com/gvisor/pkg/sentry/socket/rpcinet/syscall_rpc_go_proto"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/socket/unix/transport"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/unimpl"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/syserr"
+	"gvisor.googlesource.com/gvisor/pkg/syserror"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// socketOperations implements fs.FileOperations and socket.Socket for a socket
+// implemented using a host socket.
+type socketOperations struct {
+	fsutil.FilePipeSeek             `state:"nosave"`
+	fsutil.FileNotDirReaddir        `state:"nosave"`
+	fsutil.FileNoFsync              `state:"nosave"`
+	fsutil.FileNoMMap               `state:"nosave"`
+	fsutil.FileNoSplice             `state:"nosave"`
+	fsutil.FileNoopFlush            `state:"nosave"`
+	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
+	socket.SendReceiveTimeout
+
+	family   int    // Read-only.
+	fd       uint32 // must be O_NONBLOCK
+	wq       *waiter.Queue
+	rpcConn  *conn.RPCConnection
+	notifier *notifier.Notifier
+
+	// shState is the state of the connection with respect to shutdown. Because
+	// we're mixing non-blocking semantics on the other side we have to adapt for
+	// some strange differences between blocking and non-blocking sockets.
+	shState int32
+}
+
+// Verify that we actually implement socket.Socket.
+var _ = socket.Socket(&socketOperations{})
+
+// New creates a new RPC socket.
+func newSocketFile(ctx context.Context, stack *Stack, family int, skType int, protocol int) (*fs.File, *syserr.Error) {
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Socket{&pb.SocketRequest{Family: int64(family), Type: int64(skType | syscall.SOCK_NONBLOCK), Protocol: int64(protocol)}}}, false /* ignoreResult */)
+	<-c
+
+	res := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_Socket).Socket.Result
+	if e, ok := res.(*pb.SocketResponse_ErrorNumber); ok {
+		return nil, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+	fd := res.(*pb.SocketResponse_Fd).Fd
+
+	var wq waiter.Queue
+	stack.notifier.AddFD(fd, &wq)
+
+	dirent := socket.NewDirent(ctx, socketDevice)
+	defer dirent.DecRef()
+	return fs.NewFile(ctx, dirent, fs.FileFlags{Read: true, Write: true}, &socketOperations{
+		family:   family,
+		wq:       &wq,
+		fd:       fd,
+		rpcConn:  stack.rpcConn,
+		notifier: stack.notifier,
+	}), nil
+}
+
+func isBlockingErrno(err error) bool {
+	return err == syscall.EAGAIN || err == syscall.EWOULDBLOCK
+}
+
+func translateIOSyscallError(err error) error {
+	if isBlockingErrno(err) {
+		return syserror.ErrWouldBlock
+	}
+	return err
+}
+
+// setShutdownFlags will set the shutdown flag so we can handle blocking reads
+// after a read shutdown.
+func (s *socketOperations) setShutdownFlags(how int) {
+	var f tcpip.ShutdownFlags
+	switch how {
+	case linux.SHUT_RD:
+		f = tcpip.ShutdownRead
+	case linux.SHUT_WR:
+		f = tcpip.ShutdownWrite
+	case linux.SHUT_RDWR:
+		f = tcpip.ShutdownWrite | tcpip.ShutdownRead
+	}
+
+	// Atomically update the flags.
+	for {
+		old := atomic.LoadInt32(&s.shState)
+		if atomic.CompareAndSwapInt32(&s.shState, old, old|int32(f)) {
+			break
+		}
+	}
+}
+
+func (s *socketOperations) resetShutdownFlags() {
+	atomic.StoreInt32(&s.shState, 0)
+}
+
+func (s *socketOperations) isShutRdSet() bool {
+	return atomic.LoadInt32(&s.shState)&int32(tcpip.ShutdownRead) != 0
+}
+
+func (s *socketOperations) isShutWrSet() bool {
+	return atomic.LoadInt32(&s.shState)&int32(tcpip.ShutdownWrite) != 0
+}
+
+// Release implements fs.FileOperations.Release.
+func (s *socketOperations) Release() {
+	s.notifier.RemoveFD(s.fd)
+
+	// We always need to close the FD.
+	_, _ = s.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Close{&pb.CloseRequest{Fd: s.fd}}}, true /* ignoreResult */)
+}
+
+// Readiness implements waiter.Waitable.Readiness.
+func (s *socketOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
+	return s.notifier.NonBlockingPoll(s.fd, mask)
+}
+
+// EventRegister implements waiter.Waitable.EventRegister.
+func (s *socketOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
+	s.wq.EventRegister(e, mask)
+	s.notifier.UpdateFD(s.fd)
+}
+
+// EventUnregister implements waiter.Waitable.EventUnregister.
+func (s *socketOperations) EventUnregister(e *waiter.Entry) {
+	s.wq.EventUnregister(e)
+	s.notifier.UpdateFD(s.fd)
+}
+
+func rpcRead(t *kernel.Task, req *pb.SyscallRequest_Read) (*pb.ReadResponse_Data, *syserr.Error) {
+	s := t.NetworkContext().(*Stack)
+	id, c := s.rpcConn.NewRequest(pb.SyscallRequest{Args: req}, false /* ignoreResult */)
+	<-c
+
+	res := s.rpcConn.Request(id).Result.(*pb.SyscallResponse_Read).Read.Result
+	if e, ok := res.(*pb.ReadResponse_ErrorNumber); ok {
+		return nil, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	return res.(*pb.ReadResponse_Data), nil
+}
+
+// Read implements fs.FileOperations.Read.
+func (s *socketOperations) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
+	req := &pb.SyscallRequest_Read{&pb.ReadRequest{
+		Fd:     s.fd,
+		Length: uint32(dst.NumBytes()),
+	}}
+
+	res, se := rpcRead(ctx.(*kernel.Task), req)
+	if se == nil {
+		n, e := dst.CopyOut(ctx, res.Data)
+		return int64(n), e
+	}
+
+	return 0, se.ToError()
+}
+
+func rpcWrite(t *kernel.Task, req *pb.SyscallRequest_Write) (uint32, *syserr.Error) {
+	s := t.NetworkContext().(*Stack)
+	id, c := s.rpcConn.NewRequest(pb.SyscallRequest{Args: req}, false /* ignoreResult */)
+	<-c
+
+	res := s.rpcConn.Request(id).Result.(*pb.SyscallResponse_Write).Write.Result
+	if e, ok := res.(*pb.WriteResponse_ErrorNumber); ok {
+		return 0, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	return res.(*pb.WriteResponse_Length).Length, nil
+}
+
+// Write implements fs.FileOperations.Write.
+func (s *socketOperations) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, _ int64) (int64, error) {
+	t := ctx.(*kernel.Task)
+	v := buffer.NewView(int(src.NumBytes()))
+
+	// Copy all the data into the buffer.
+	if _, err := src.CopyIn(t, v); err != nil {
+		return 0, err
+	}
+
+	n, err := rpcWrite(t, &pb.SyscallRequest_Write{&pb.WriteRequest{Fd: s.fd, Data: v}})
+	if n > 0 && n < uint32(src.NumBytes()) {
+		// The FileOperations.Write interface expects us to return ErrWouldBlock in
+		// the event of a partial write.
+		return int64(n), syserror.ErrWouldBlock
+	}
+	return int64(n), err.ToError()
+}
+
+func rpcConnect(t *kernel.Task, fd uint32, sockaddr []byte) *syserr.Error {
+	s := t.NetworkContext().(*Stack)
+	id, c := s.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Connect{&pb.ConnectRequest{Fd: uint32(fd), Address: sockaddr}}}, false /* ignoreResult */)
+	<-c
+
+	if e := s.rpcConn.Request(id).Result.(*pb.SyscallResponse_Connect).Connect.ErrorNumber; e != 0 {
+		return syserr.FromHost(syscall.Errno(e))
+	}
+	return nil
+}
+
+// Connect implements socket.Socket.Connect.
+func (s *socketOperations) Connect(t *kernel.Task, sockaddr []byte, blocking bool) *syserr.Error {
+	if !blocking {
+		e := rpcConnect(t, s.fd, sockaddr)
+		if e == nil {
+			// Reset the shutdown state on new connects.
+			s.resetShutdownFlags()
+		}
+		return e
+	}
+
+	// Register for notification when the endpoint becomes writable, then
+	// initiate the connection.
+	e, ch := waiter.NewChannelEntry(nil)
+	s.EventRegister(&e, waiter.EventOut|waiter.EventIn|waiter.EventHUp)
+	defer s.EventUnregister(&e)
+	for {
+		if err := rpcConnect(t, s.fd, sockaddr); err == nil || err != syserr.ErrInProgress && err != syserr.ErrAlreadyInProgress {
+			if err == nil {
+				// Reset the shutdown state on new connects.
+				s.resetShutdownFlags()
+			}
+			return err
+		}
+
+		// It's pending, so we have to wait for a notification, and fetch the
+		// result once the wait completes.
+		if err := t.Block(ch); err != nil {
+			return syserr.FromError(err)
+		}
+	}
+}
+
+func rpcAccept(t *kernel.Task, fd uint32, peer bool) (*pb.AcceptResponse_ResultPayload, *syserr.Error) {
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Accept{&pb.AcceptRequest{Fd: fd, Peer: peer, Flags: syscall.SOCK_NONBLOCK}}}, false /* ignoreResult */)
+	<-c
+
+	res := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_Accept).Accept.Result
+	if e, ok := res.(*pb.AcceptResponse_ErrorNumber); ok {
+		return nil, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+	return res.(*pb.AcceptResponse_Payload).Payload, nil
+}
+
+// Accept implements socket.Socket.Accept.
+func (s *socketOperations) Accept(t *kernel.Task, peerRequested bool, flags int, blocking bool) (kdefs.FD, interface{}, uint32, *syserr.Error) {
+	payload, se := rpcAccept(t, s.fd, peerRequested)
+
+	// Check if we need to block.
+	if blocking && se == syserr.ErrTryAgain {
+		// Register for notifications.
+		e, ch := waiter.NewChannelEntry(nil)
+		// FIXME(b/119878986): This waiter.EventHUp is a partial
+		// measure, need to figure out how to translate linux events to
+		// internal events.
+		s.EventRegister(&e, waiter.EventIn|waiter.EventHUp)
+		defer s.EventUnregister(&e)
+
+		// Try to accept the connection again; if it fails, then wait until we
+		// get a notification.
+		for {
+			if payload, se = rpcAccept(t, s.fd, peerRequested); se != syserr.ErrTryAgain {
+				break
+			}
+
+			if err := t.Block(ch); err != nil {
+				return 0, nil, 0, syserr.FromError(err)
+			}
+		}
+	}
+
+	// Handle any error from accept.
+	if se != nil {
+		return 0, nil, 0, se
+	}
+
+	var wq waiter.Queue
+	s.notifier.AddFD(payload.Fd, &wq)
+
+	dirent := socket.NewDirent(t, socketDevice)
+	defer dirent.DecRef()
+	file := fs.NewFile(t, dirent, fs.FileFlags{Read: true, Write: true, NonBlocking: flags&linux.SOCK_NONBLOCK != 0}, &socketOperations{
+		wq:       &wq,
+		fd:       payload.Fd,
+		rpcConn:  s.rpcConn,
+		notifier: s.notifier,
+	})
+	defer file.DecRef()
+
+	fdFlags := kernel.FDFlags{
+		CloseOnExec: flags&linux.SOCK_CLOEXEC != 0,
+	}
+	fd, err := t.FDMap().NewFDFrom(0, file, fdFlags, t.ThreadGroup().Limits())
+	if err != nil {
+		return 0, nil, 0, syserr.FromError(err)
+	}
+	t.Kernel().RecordSocket(file, s.family)
+
+	if peerRequested {
+		return fd, payload.Address.Address, payload.Address.Length, nil
+	}
+
+	return fd, nil, 0, nil
+}
+
+// Bind implements socket.Socket.Bind.
+func (s *socketOperations) Bind(t *kernel.Task, sockaddr []byte) *syserr.Error {
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Bind{&pb.BindRequest{Fd: s.fd, Address: sockaddr}}}, false /* ignoreResult */)
+	<-c
+
+	if e := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_Bind).Bind.ErrorNumber; e != 0 {
+		return syserr.FromHost(syscall.Errno(e))
+	}
+	return nil
+}
+
+// Listen implements socket.Socket.Listen.
+func (s *socketOperations) Listen(t *kernel.Task, backlog int) *syserr.Error {
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Listen{&pb.ListenRequest{Fd: s.fd, Backlog: int64(backlog)}}}, false /* ignoreResult */)
+	<-c
+
+	if e := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_Listen).Listen.ErrorNumber; e != 0 {
+		return syserr.FromHost(syscall.Errno(e))
+	}
+	return nil
+}
+
+// Shutdown implements socket.Socket.Shutdown.
+func (s *socketOperations) Shutdown(t *kernel.Task, how int) *syserr.Error {
+	// We save the shutdown state because of strange differences on linux
+	// related to recvs on blocking vs. non-blocking sockets after a SHUT_RD.
+	// We need to emulate that behavior on the blocking side.
+	// TODO(b/120096741): There is a possible race that can exist with loopback,
+	// where data could possibly be lost.
+	s.setShutdownFlags(how)
+
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Shutdown{&pb.ShutdownRequest{Fd: s.fd, How: int64(how)}}}, false /* ignoreResult */)
+	<-c
+
+	if e := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_Shutdown).Shutdown.ErrorNumber; e != 0 {
+		return syserr.FromHost(syscall.Errno(e))
+	}
+
+	return nil
+}
+
+// GetSockOpt implements socket.Socket.GetSockOpt.
+func (s *socketOperations) GetSockOpt(t *kernel.Task, level int, name int, outLen int) (interface{}, *syserr.Error) {
+	// SO_RCVTIMEO and SO_SNDTIMEO are special because blocking is performed
+	// within the sentry.
+	if level == linux.SOL_SOCKET && name == linux.SO_RCVTIMEO {
+		if outLen < linux.SizeOfTimeval {
+			return nil, syserr.ErrInvalidArgument
+		}
+
+		return linux.NsecToTimeval(s.RecvTimeout()), nil
+	}
+	if level == linux.SOL_SOCKET && name == linux.SO_SNDTIMEO {
+		if outLen < linux.SizeOfTimeval {
+			return nil, syserr.ErrInvalidArgument
+		}
+
+		return linux.NsecToTimeval(s.SendTimeout()), nil
+	}
+
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_GetSockOpt{&pb.GetSockOptRequest{Fd: s.fd, Level: int64(level), Name: int64(name), Length: uint32(outLen)}}}, false /* ignoreResult */)
+	<-c
+
+	res := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_GetSockOpt).GetSockOpt.Result
+	if e, ok := res.(*pb.GetSockOptResponse_ErrorNumber); ok {
+		return nil, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	return res.(*pb.GetSockOptResponse_Opt).Opt, nil
+}
+
+// SetSockOpt implements socket.Socket.SetSockOpt.
+func (s *socketOperations) SetSockOpt(t *kernel.Task, level int, name int, opt []byte) *syserr.Error {
+	// Because blocking actually happens within the sentry we need to inspect
+	// this socket option to determine if it's a SO_RCVTIMEO or SO_SNDTIMEO,
+	// and if so, we will save it and use it as the deadline for recv(2)
+	// or send(2) related syscalls.
+	if level == linux.SOL_SOCKET && name == linux.SO_RCVTIMEO {
+		if len(opt) < linux.SizeOfTimeval {
+			return syserr.ErrInvalidArgument
+		}
+
+		var v linux.Timeval
+		binary.Unmarshal(opt[:linux.SizeOfTimeval], usermem.ByteOrder, &v)
+		if v.Usec < 0 || v.Usec >= int64(time.Second/time.Microsecond) {
+			return syserr.ErrDomain
+		}
+		s.SetRecvTimeout(v.ToNsecCapped())
+		return nil
+	}
+	if level == linux.SOL_SOCKET && name == linux.SO_SNDTIMEO {
+		if len(opt) < linux.SizeOfTimeval {
+			return syserr.ErrInvalidArgument
+		}
+
+		var v linux.Timeval
+		binary.Unmarshal(opt[:linux.SizeOfTimeval], usermem.ByteOrder, &v)
+		if v.Usec < 0 || v.Usec >= int64(time.Second/time.Microsecond) {
+			return syserr.ErrDomain
+		}
+		s.SetSendTimeout(v.ToNsecCapped())
+		return nil
+	}
+
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_SetSockOpt{&pb.SetSockOptRequest{Fd: s.fd, Level: int64(level), Name: int64(name), Opt: opt}}}, false /* ignoreResult */)
+	<-c
+
+	if e := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_SetSockOpt).SetSockOpt.ErrorNumber; e != 0 {
+		return syserr.FromHost(syscall.Errno(e))
+	}
+	return nil
+}
+
+// GetPeerName implements socket.Socket.GetPeerName.
+func (s *socketOperations) GetPeerName(t *kernel.Task) (interface{}, uint32, *syserr.Error) {
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_GetPeerName{&pb.GetPeerNameRequest{Fd: s.fd}}}, false /* ignoreResult */)
+	<-c
+
+	res := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_GetPeerName).GetPeerName.Result
+	if e, ok := res.(*pb.GetPeerNameResponse_ErrorNumber); ok {
+		return nil, 0, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	addr := res.(*pb.GetPeerNameResponse_Address).Address
+	return addr.Address, addr.Length, nil
+}
+
+// GetSockName implements socket.Socket.GetSockName.
+func (s *socketOperations) GetSockName(t *kernel.Task) (interface{}, uint32, *syserr.Error) {
+	stack := t.NetworkContext().(*Stack)
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_GetSockName{&pb.GetSockNameRequest{Fd: s.fd}}}, false /* ignoreResult */)
+	<-c
+
+	res := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_GetSockName).GetSockName.Result
+	if e, ok := res.(*pb.GetSockNameResponse_ErrorNumber); ok {
+		return nil, 0, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	addr := res.(*pb.GetSockNameResponse_Address).Address
+	return addr.Address, addr.Length, nil
+}
+
+func rpcIoctl(t *kernel.Task, fd, cmd uint32, arg []byte) ([]byte, error) {
+	stack := t.NetworkContext().(*Stack)
+
+	id, c := stack.rpcConn.NewRequest(pb.SyscallRequest{Args: &pb.SyscallRequest_Ioctl{&pb.IOCtlRequest{Fd: fd, Cmd: cmd, Arg: arg}}}, false /* ignoreResult */)
+	<-c
+
+	res := stack.rpcConn.Request(id).Result.(*pb.SyscallResponse_Ioctl).Ioctl.Result
+	if e, ok := res.(*pb.IOCtlResponse_ErrorNumber); ok {
+		return nil, syscall.Errno(e.ErrorNumber)
+	}
+
+	return res.(*pb.IOCtlResponse_Value).Value, nil
+}
+
+// ifconfIoctlFromStack populates a struct ifconf for the SIOCGIFCONF ioctl.
+func ifconfIoctlFromStack(ctx context.Context, io usermem.IO, ifc *linux.IFConf) error {
+	// If Ptr is NULL, return the necessary buffer size via Len.
+	// Otherwise, write up to Len bytes starting at Ptr containing ifreq
+	// structs.
+	t := ctx.(*kernel.Task)
+	s := t.NetworkContext().(*Stack)
+	if s == nil {
+		return syserr.ErrNoDevice.ToError()
+	}
+
+	if ifc.Ptr == 0 {
+		ifc.Len = int32(len(s.Interfaces())) * int32(linux.SizeOfIFReq)
+		return nil
+	}
+
+	max := ifc.Len
+	ifc.Len = 0
+	for key, ifaceAddrs := range s.InterfaceAddrs() {
+		iface := s.Interfaces()[key]
+		for _, ifaceAddr := range ifaceAddrs {
+			// Don't write past the end of the buffer.
+			if ifc.Len+int32(linux.SizeOfIFReq) > max {
+				break
+			}
+			if ifaceAddr.Family != linux.AF_INET {
+				continue
+			}
+
+			// Populate ifr.ifr_addr.
+			ifr := linux.IFReq{}
+			ifr.SetName(iface.Name)
+			usermem.ByteOrder.PutUint16(ifr.Data[0:2], uint16(ifaceAddr.Family))
+			usermem.ByteOrder.PutUint16(ifr.Data[2:4], 0)
+			copy(ifr.Data[4:8], ifaceAddr.Addr[:4])
+
+			// Copy the ifr to userspace.
+			dst := uintptr(ifc.Ptr) + uintptr(ifc.Len)
+			ifc.Len += int32(linux.SizeOfIFReq)
+			if _, err := usermem.CopyObjectOut(ctx, io, usermem.Addr(dst), ifr, usermem.IOOpts{
+				AddressSpaceActive: true,
+			}); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// Ioctl implements fs.FileOperations.Ioctl.
+func (s *socketOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	t := ctx.(*kernel.Task)
+
+	cmd := uint32(args[1].Int())
+	arg := args[2].Pointer()
+
+	var buf []byte
+	switch cmd {
+	// The following ioctls take 4 byte argument parameters.
+	case syscall.TIOCINQ,
+		syscall.TIOCOUTQ:
+		buf = make([]byte, 4)
+	// The following ioctls have args which are sizeof(struct ifreq).
+	case syscall.SIOCGIFADDR,
+		syscall.SIOCGIFBRDADDR,
+		syscall.SIOCGIFDSTADDR,
+		syscall.SIOCGIFFLAGS,
+		syscall.SIOCGIFHWADDR,
+		syscall.SIOCGIFINDEX,
+		syscall.SIOCGIFMAP,
+		syscall.SIOCGIFMETRIC,
+		syscall.SIOCGIFMTU,
+		syscall.SIOCGIFNAME,
+		syscall.SIOCGIFNETMASK,
+		syscall.SIOCGIFTXQLEN:
+		buf = make([]byte, linux.SizeOfIFReq)
+	case syscall.SIOCGIFCONF:
+		// SIOCGIFCONF has slightly different behavior than the others, in that it
+		// will need to populate the array of ifreqs.
+		var ifc linux.IFConf
+		if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &ifc, usermem.IOOpts{
+			AddressSpaceActive: true,
+		}); err != nil {
+			return 0, err
+		}
+
+		if err := ifconfIoctlFromStack(ctx, io, &ifc); err != nil {
+			return 0, err
+		}
+		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), ifc, usermem.IOOpts{
+			AddressSpaceActive: true,
+		})
+
+		return 0, err
+
+	case linux.SIOCGIFMEM, linux.SIOCGIFPFLAGS, linux.SIOCGMIIPHY, linux.SIOCGMIIREG:
+		unimpl.EmitUnimplementedEvent(ctx)
+
+	default:
+		return 0, syserror.ENOTTY
+	}
+
+	_, err := io.CopyIn(ctx, arg, buf, usermem.IOOpts{
+		AddressSpaceActive: true,
+	})
+
+	if err != nil {
+		return 0, err
+	}
+
+	v, err := rpcIoctl(t, s.fd, cmd, buf)
+	if err != nil {
+		return 0, err
+	}
+
+	if len(v) != len(buf) {
+		return 0, syserror.EINVAL
+	}
+
+	_, err = io.CopyOut(ctx, arg, v, usermem.IOOpts{
+		AddressSpaceActive: true,
+	})
+	return 0, err
+}
+
+func rpcRecvMsg(t *kernel.Task, req *pb.SyscallRequest_Recvmsg) (*pb.RecvmsgResponse_ResultPayload, *syserr.Error) {
+	s := t.NetworkContext().(*Stack)
+	id, c := s.rpcConn.NewRequest(pb.SyscallRequest{Args: req}, false /* ignoreResult */)
+	<-c
+
+	res := s.rpcConn.Request(id).Result.(*pb.SyscallResponse_Recvmsg).Recvmsg.Result
+	if e, ok := res.(*pb.RecvmsgResponse_ErrorNumber); ok {
+		return nil, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	return res.(*pb.RecvmsgResponse_Payload).Payload, nil
+}
+
+// Because we only support SO_TIMESTAMP we will search control messages for
+// that value and set it if so, all other control messages will be ignored.
+func (s *socketOperations) extractControlMessages(payload *pb.RecvmsgResponse_ResultPayload) socket.ControlMessages {
+	c := socket.ControlMessages{}
+	if len(payload.GetCmsgData()) > 0 {
+		// Parse the control messages looking for SO_TIMESTAMP.
+		msgs, e := syscall.ParseSocketControlMessage(payload.GetCmsgData())
+		if e != nil {
+			return socket.ControlMessages{}
+		}
+		for _, m := range msgs {
+			if m.Header.Level != linux.SOL_SOCKET || m.Header.Type != linux.SO_TIMESTAMP {
+				continue
+			}
+
+			// Let's parse the time stamp and set it.
+			if len(m.Data) < linux.SizeOfTimeval {
+				// Give up on locating the SO_TIMESTAMP option.
+				return socket.ControlMessages{}
+			}
+
+			var v linux.Timeval
+			binary.Unmarshal(m.Data[:linux.SizeOfTimeval], usermem.ByteOrder, &v)
+			c.IP.HasTimestamp = true
+			c.IP.Timestamp = v.ToNsecCapped()
+			break
+		}
+	}
+	return c
+}
+
+// RecvMsg implements socket.Socket.RecvMsg.
+func (s *socketOperations) RecvMsg(t *kernel.Task, dst usermem.IOSequence, flags int, haveDeadline bool, deadline ktime.Time, senderRequested bool, controlDataLen uint64) (int, int, interface{}, uint32, socket.ControlMessages, *syserr.Error) {
+	req := &pb.SyscallRequest_Recvmsg{&pb.RecvmsgRequest{
+		Fd:         s.fd,
+		Length:     uint32(dst.NumBytes()),
+		Sender:     senderRequested,
+		Trunc:      flags&linux.MSG_TRUNC != 0,
+		Peek:       flags&linux.MSG_PEEK != 0,
+		CmsgLength: uint32(controlDataLen),
+	}}
+
+	res, err := rpcRecvMsg(t, req)
+	if err == nil {
+		var e error
+		var n int
+		if len(res.Data) > 0 {
+			n, e = dst.CopyOut(t, res.Data)
+			if e == nil && n != len(res.Data) {
+				panic("CopyOut failed to copy full buffer")
+			}
+		}
+		c := s.extractControlMessages(res)
+		return int(res.Length), 0, res.Address.GetAddress(), res.Address.GetLength(), c, syserr.FromError(e)
+	}
+	if err != syserr.ErrWouldBlock && err != syserr.ErrTryAgain || flags&linux.MSG_DONTWAIT != 0 {
+		return 0, 0, nil, 0, socket.ControlMessages{}, err
+	}
+
+	// We'll have to block. Register for notifications and keep trying to
+	// send all the data.
+	e, ch := waiter.NewChannelEntry(nil)
+	s.EventRegister(&e, waiter.EventIn)
+	defer s.EventUnregister(&e)
+
+	for {
+		res, err := rpcRecvMsg(t, req)
+		if err == nil {
+			var e error
+			var n int
+			if len(res.Data) > 0 {
+				n, e = dst.CopyOut(t, res.Data)
+				if e == nil && n != len(res.Data) {
+					panic("CopyOut failed to copy full buffer")
+				}
+			}
+			c := s.extractControlMessages(res)
+			return int(res.Length), 0, res.Address.GetAddress(), res.Address.GetLength(), c, syserr.FromError(e)
+		}
+		if err != syserr.ErrWouldBlock && err != syserr.ErrTryAgain {
+			return 0, 0, nil, 0, socket.ControlMessages{}, err
+		}
+
+		if s.isShutRdSet() {
+			// Blocking would have caused us to block indefinitely so we return 0,
+			// this is the same behavior as Linux.
+			return 0, 0, nil, 0, socket.ControlMessages{}, nil
+		}
+
+		if err := t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
+			if err == syserror.ETIMEDOUT {
+				return 0, 0, nil, 0, socket.ControlMessages{}, syserr.ErrTryAgain
+			}
+			return 0, 0, nil, 0, socket.ControlMessages{}, syserr.FromError(err)
+		}
+	}
+}
+
+func rpcSendMsg(t *kernel.Task, req *pb.SyscallRequest_Sendmsg) (uint32, *syserr.Error) {
+	s := t.NetworkContext().(*Stack)
+	id, c := s.rpcConn.NewRequest(pb.SyscallRequest{Args: req}, false /* ignoreResult */)
+	<-c
+
+	res := s.rpcConn.Request(id).Result.(*pb.SyscallResponse_Sendmsg).Sendmsg.Result
+	if e, ok := res.(*pb.SendmsgResponse_ErrorNumber); ok {
+		return 0, syserr.FromHost(syscall.Errno(e.ErrorNumber))
+	}
+
+	return res.(*pb.SendmsgResponse_Length).Length, nil
+}
+
+// SendMsg implements socket.Socket.SendMsg.
+func (s *socketOperations) SendMsg(t *kernel.Task, src usermem.IOSequence, to []byte, flags int, haveDeadline bool, deadline ktime.Time, controlMessages socket.ControlMessages) (int, *syserr.Error) {
+	// Whitelist flags.
+	if flags&^(syscall.MSG_DONTWAIT|syscall.MSG_EOR|syscall.MSG_FASTOPEN|syscall.MSG_MORE|syscall.MSG_NOSIGNAL) != 0 {
+		return 0, syserr.ErrInvalidArgument
+	}
+
+	// Reject Unix control messages.
+	if !controlMessages.Unix.Empty() {
+		return 0, syserr.ErrInvalidArgument
+	}
+
+	v := buffer.NewView(int(src.NumBytes()))
+
+	// Copy all the data into the buffer.
+	if _, err := src.CopyIn(t, v); err != nil {
+		return 0, syserr.FromError(err)
+	}
+
+	// TODO(bgeffon): this needs to change to map directly to a SendMsg syscall
+	// in the RPC.
+	totalWritten := 0
+	n, err := rpcSendMsg(t, &pb.SyscallRequest_Sendmsg{&pb.SendmsgRequest{
+		Fd:          uint32(s.fd),
+		Data:        v,
+		Address:     to,
+		More:        flags&linux.MSG_MORE != 0,
+		EndOfRecord: flags&linux.MSG_EOR != 0,
+	}})
+
+	if err != syserr.ErrWouldBlock && err != syserr.ErrTryAgain || flags&linux.MSG_DONTWAIT != 0 {
+		return int(n), err
+	}
+
+	if n > 0 {
+		totalWritten += int(n)
+		v.TrimFront(int(n))
+	}
+
+	// We'll have to block. Register for notification and keep trying to
+	// send all the data.
+	e, ch := waiter.NewChannelEntry(nil)
+	s.EventRegister(&e, waiter.EventOut)
+	defer s.EventUnregister(&e)
+
+	for {
+		n, err := rpcSendMsg(t, &pb.SyscallRequest_Sendmsg{&pb.SendmsgRequest{
+			Fd:          uint32(s.fd),
+			Data:        v,
+			Address:     to,
+			More:        flags&linux.MSG_MORE != 0,
+			EndOfRecord: flags&linux.MSG_EOR != 0,
+		}})
+
+		if n > 0 {
+			totalWritten += int(n)
+			v.TrimFront(int(n))
+
+			if err == nil && totalWritten < int(src.NumBytes()) {
+				continue
+			}
+		}
+
+		if err != syserr.ErrWouldBlock && err != syserr.ErrTryAgain {
+			// We eat the error in this situation.
+			return int(totalWritten), nil
+		}
+
+		if err := t.BlockWithDeadline(ch, haveDeadline, deadline); err != nil {
+			if err == syserror.ETIMEDOUT {
+				return int(totalWritten), syserr.ErrTryAgain
+			}
+			return int(totalWritten), syserr.FromError(err)
+		}
+	}
+}
+
+type socketProvider struct {
+	family int
+}
+
+// Socket implements socket.Provider.Socket.
+func (p *socketProvider) Socket(t *kernel.Task, stypeflags transport.SockType, protocol int) (*fs.File, *syserr.Error) {
+	// Check that we are using the RPC network stack.
+	stack := t.NetworkContext()
+	if stack == nil {
+		return nil, nil
+	}
+
+	s, ok := stack.(*Stack)
+	if !ok {
+		return nil, nil
+	}
+
+	// Only accept TCP and UDP.
+	//
+	// Try to restrict the flags we will accept to minimize backwards
+	// incompatibility with netstack.
+	stype := int(stypeflags) & linux.SOCK_TYPE_MASK
+	switch stype {
+	case syscall.SOCK_STREAM:
+		switch protocol {
+		case 0, syscall.IPPROTO_TCP:
+			// ok
+		default:
+			return nil, nil
+		}
+	case syscall.SOCK_DGRAM:
+		switch protocol {
+		case 0, syscall.IPPROTO_UDP:
+			// ok
+		default:
+			return nil, nil
+		}
+	default:
+		return nil, nil
+	}
+
+	return newSocketFile(t, s, p.family, stype, 0)
+}
+
+// Pair implements socket.Provider.Pair.
+func (p *socketProvider) Pair(t *kernel.Task, stype transport.SockType, protocol int) (*fs.File, *fs.File, *syserr.Error) {
+	// Not supported by AF_INET/AF_INET6.
+	return nil, nil, nil
+}
+
+func init() {
+	for _, family := range []int{syscall.AF_INET, syscall.AF_INET6} {
+		socket.RegisterProvider(family, &socketProvider{family})
+	}
+}