sentry: Get "ip link" working.

In Linux, many UDS ioctls are passed through to the NIC driver. We do the same
here, passing ioctl calls to Unix sockets through to epsocket.

In Linux you can see this path at net/socket.c:sock_ioctl, which calls
sock_do_ioctl, which calls net/core/dev_ioctl.c:dev_ioctl.

SIOCGIFNAME is also added.

PiperOrigin-RevId: 197167508
Change-Id: I62c326a4792bd0a473e9c9108aafb6a6354f2b64

1 files changed, 119 insertions, 107 deletions

diff --git a/pkg/sentry/socket/epsocket/epsocket.go b/pkg/sentry/socket/epsocket/epsocket.go
index 18cb70c96..2495ba459 100644
--- a/pkg/sentry/socket/epsocket/epsocket.go
+++ b/pkg/sentry/socket/epsocket/epsocket.go
@@ -33,7 +33,6 @@ import (
 
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
 	"gvisor.googlesource.com/gvisor/pkg/binary"
-	"gvisor.googlesource.com/gvisor/pkg/log"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
@@ -703,18 +702,18 @@ func SetSockOpt(t *kernel.Task, s socket.Socket, ep commonEndpoint, level int, n
 			v := usermem.ByteOrder.Uint32(optVal)
 			return syserr.TranslateNetstackError(ep.SetSockOpt(tcpip.V6OnlyOption(v)))
 		}
-	}
-
-	// FIXME: Disallow IP-level multicast group options by
-	// default. These will need to be supported by appropriately plumbing
-	// the level through to the network stack (if at all). However, we
-	// still allow setting TTL, and multicast-enable/disable type options.
-	if level == 0 {
+	case syscall.SOL_IP:
 		const (
+			_IP_MULTICAST_IF   = 32
 			_IP_ADD_MEMBERSHIP = 35
 			_MCAST_JOIN_GROUP  = 42
 		)
-		if name == _IP_ADD_MEMBERSHIP || name == _MCAST_JOIN_GROUP {
+		switch name {
+		case _IP_ADD_MEMBERSHIP, _MCAST_JOIN_GROUP, _IP_MULTICAST_IF:
+			// FIXME: Disallow IP-level multicast group options by
+			// default. These will need to be supported by appropriately plumbing
+			// the level through to the network stack (if at all). However, we
+			// still allow setting TTL, and multicast-enable/disable type options.
 			return syserr.ErrInvalidArgument
 		}
 	}
@@ -1033,8 +1032,99 @@ func (s *SocketOperations) SendMsg(t *kernel.Task, src usermem.IOSequence, to []
 	}
 }
 
+// Ioctl implements fs.FileOperations.Ioctl.
+func (s *SocketOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	return Ioctl(ctx, s.Endpoint, io, args)
+}
+
+// Ioctl performs a socket ioctl.
+func Ioctl(ctx context.Context, ep commonEndpoint, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	switch arg := int(args[1].Int()); arg {
+	case syscall.SIOCGIFFLAGS,
+		syscall.SIOCGIFADDR,
+		syscall.SIOCGIFBRDADDR,
+		syscall.SIOCGIFDSTADDR,
+		syscall.SIOCGIFHWADDR,
+		syscall.SIOCGIFINDEX,
+		syscall.SIOCGIFMAP,
+		syscall.SIOCGIFMETRIC,
+		syscall.SIOCGIFMTU,
+		syscall.SIOCGIFNAME,
+		syscall.SIOCGIFNETMASK,
+		syscall.SIOCGIFTXQLEN:
+
+		var ifr linux.IFReq
+		if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &ifr, usermem.IOOpts{
+			AddressSpaceActive: true,
+		}); err != nil {
+			return 0, err
+		}
+		if err := interfaceIoctl(ctx, io, arg, &ifr); err != nil {
+			return 0, err.ToError()
+		}
+		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), &ifr, usermem.IOOpts{
+			AddressSpaceActive: true,
+		})
+		return 0, err
+
+	case syscall.SIOCGIFCONF:
+		// Return a list of interface addresses or the buffer size
+		// necessary to hold the list.
+		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 := ifconfIoctl(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.TIOCINQ:
+		var v tcpip.ReceiveQueueSizeOption
+		if err := ep.GetSockOpt(&v); err != nil {
+			return 0, syserr.TranslateNetstackError(err).ToError()
+		}
+
+		if v > math.MaxInt32 {
+			v = math.MaxInt32
+		}
+		// Copy result to user-space.
+		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(v), usermem.IOOpts{
+			AddressSpaceActive: true,
+		})
+		return 0, err
+
+	case linux.TIOCOUTQ:
+		var v tcpip.SendQueueSizeOption
+		if err := ep.GetSockOpt(&v); err != nil {
+			return 0, syserr.TranslateNetstackError(err).ToError()
+		}
+
+		if v > math.MaxInt32 {
+			v = math.MaxInt32
+		}
+
+		// Copy result to user-space.
+		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(v), usermem.IOOpts{
+			AddressSpaceActive: true,
+		})
+		return 0, err
+
+	}
+
+	return 0, syserror.ENOTTY
+}
+
 // interfaceIoctl implements interface requests.
-func (s *SocketOperations) interfaceIoctl(ctx context.Context, io usermem.IO, arg int, ifr *linux.IFReq) *syserr.Error {
+func interfaceIoctl(ctx context.Context, io usermem.IO, arg int, ifr *linux.IFReq) *syserr.Error {
 	var (
 		iface inet.Interface
 		index int32
@@ -1044,9 +1134,23 @@ func (s *SocketOperations) interfaceIoctl(ctx context.Context, io usermem.IO, ar
 	// Find the relevant device.
 	stack := inet.StackFromContext(ctx)
 	if stack == nil {
-		log.Warningf("Couldn't find a network stack.")
-		return syserr.ErrInvalidArgument
+		return syserr.ErrNoDevice
 	}
+
+	// SIOCGIFNAME uses ifr.ifr_ifindex rather than ifr.ifr_name to
+	// identify a device.
+	if arg == syscall.SIOCGIFNAME {
+		// Gets the name of the interface given the interface index
+		// stored in ifr_ifindex.
+		index = int32(usermem.ByteOrder.Uint32(ifr.Data[:4]))
+		if iface, ok := stack.Interfaces()[index]; ok {
+			ifr.SetName(iface.Name)
+			return nil
+		}
+		return syserr.ErrNoDevice
+	}
+
+	// Find the relevant device.
 	for index, iface = range stack.Interfaces() {
 		if iface.Name == ifr.Name() {
 			found = true
@@ -1137,68 +1241,16 @@ func (s *SocketOperations) interfaceIoctl(ctx context.Context, io usermem.IO, ar
 	return nil
 }
 
-// Ioctl implements fs.FileOperations.Ioctl.
-func (s *SocketOperations) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
-	switch arg := int(args[1].Int()); arg {
-	case syscall.SIOCGIFFLAGS,
-		syscall.SIOCGIFADDR,
-		syscall.SIOCGIFBRDADDR,
-		syscall.SIOCGIFDSTADDR,
-		syscall.SIOCGIFHWADDR,
-		syscall.SIOCGIFINDEX,
-		syscall.SIOCGIFMAP,
-		syscall.SIOCGIFMETRIC,
-		syscall.SIOCGIFMTU,
-		syscall.SIOCGIFNETMASK,
-		syscall.SIOCGIFTXQLEN:
-
-		var ifr linux.IFReq
-		if _, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &ifr, usermem.IOOpts{
-			AddressSpaceActive: true,
-		}); err != nil {
-			return 0, err
-		}
-		if err := s.interfaceIoctl(ctx, io, arg, &ifr); err != nil {
-			return 0, err.ToError()
-		}
-		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), &ifr, usermem.IOOpts{
-			AddressSpaceActive: true,
-		})
-		return 0, err
-	case syscall.SIOCGIFCONF:
-		// Return a list of interface addresses or the buffer size
-		// necessary to hold the list.
-		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 := s.ifconfIoctl(ctx, io, &ifc); err != nil {
-			return 0, err
-		}
-
-		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), ifc, usermem.IOOpts{
-			AddressSpaceActive: true,
-		})
-
-		return 0, err
-	}
-
-	return Ioctl(ctx, s.Endpoint, io, args)
-}
-
 // ifconfIoctl populates a struct ifconf for the SIOCGIFCONF ioctl.
-func (s *SocketOperations) ifconfIoctl(ctx context.Context, io usermem.IO, ifc *linux.IFConf) error {
+func ifconfIoctl(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.
 	stack := inet.StackFromContext(ctx)
 	if stack == nil {
-		log.Warningf("Couldn't find a network stack.")
-		return syserr.ErrInvalidArgument.ToError()
+		return syserr.ErrNoDevice.ToError()
 	}
+
 	if ifc.Ptr == 0 {
 		ifc.Len = int32(len(stack.Interfaces())) * int32(linux.SizeOfIFReq)
 		return nil
@@ -1236,43 +1288,3 @@ func (s *SocketOperations) ifconfIoctl(ctx context.Context, io usermem.IO, ifc *
 	}
 	return nil
 }
-
-// Ioctl implements fs.FileOperations.Ioctl for sockets backed by a
-// commonEndpoint.
-func Ioctl(ctx context.Context, ep commonEndpoint, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
-	// Switch on ioctl request.
-	switch int(args[1].Int()) {
-	case linux.TIOCINQ:
-		var v tcpip.ReceiveQueueSizeOption
-		if err := ep.GetSockOpt(&v); err != nil {
-			return 0, syserr.TranslateNetstackError(err).ToError()
-		}
-
-		if v > math.MaxInt32 {
-			v = math.MaxInt32
-		}
-		// Copy result to user-space.
-		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(v), usermem.IOOpts{
-			AddressSpaceActive: true,
-		})
-		return 0, err
-
-	case linux.TIOCOUTQ:
-		var v tcpip.SendQueueSizeOption
-		if err := ep.GetSockOpt(&v); err != nil {
-			return 0, syserr.TranslateNetstackError(err).ToError()
-		}
-
-		if v > math.MaxInt32 {
-			v = math.MaxInt32
-		}
-
-		// Copy result to user-space.
-		_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(v), usermem.IOOpts{
-			AddressSpaceActive: true,
-		})
-		return 0, err
-	}
-
-	return 0, syserror.ENOTTY
-}