From 6768e6c59ec252854a1633e184b69dc5723ac3f3 Mon Sep 17 00:00:00 2001 From: Ghanan Gowripalan Date: Thu, 8 Oct 2020 16:14:01 -0700 Subject: Do not resolve routes immediately When a response needs to be sent to an incoming packet, the stack should consult its neighbour table to determine the remote address's link address. When an entry does not exist in the stack's neighbor table, the stack should queue the packet while link resolution completes. See comments. PiperOrigin-RevId: 336185457 --- pkg/sentry/fs/dev/BUILD | 1 + pkg/sentry/fs/dev/net_tun.go | 52 +++++++++++++++++++++++++++----------------- 2 files changed, 33 insertions(+), 20 deletions(-) (limited to 'pkg/sentry/fs/dev') diff --git a/pkg/sentry/fs/dev/BUILD b/pkg/sentry/fs/dev/BUILD index 9379a4d7b..6b7b451b8 100644 --- a/pkg/sentry/fs/dev/BUILD +++ b/pkg/sentry/fs/dev/BUILD @@ -34,6 +34,7 @@ go_library( "//pkg/sentry/socket/netstack", "//pkg/syserror", "//pkg/tcpip/link/tun", + "//pkg/tcpip/network/arp", "//pkg/usermem", "//pkg/waiter", ], diff --git a/pkg/sentry/fs/dev/net_tun.go b/pkg/sentry/fs/dev/net_tun.go index 5f8c9b5a2..19ffdec47 100644 --- a/pkg/sentry/fs/dev/net_tun.go +++ b/pkg/sentry/fs/dev/net_tun.go @@ -15,6 +15,8 @@ package dev import ( + "fmt" + "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" @@ -25,6 +27,7 @@ import ( "gvisor.dev/gvisor/pkg/sentry/socket/netstack" "gvisor.dev/gvisor/pkg/syserror" "gvisor.dev/gvisor/pkg/tcpip/link/tun" + "gvisor.dev/gvisor/pkg/tcpip/network/arp" "gvisor.dev/gvisor/pkg/usermem" "gvisor.dev/gvisor/pkg/waiter" ) @@ -60,7 +63,7 @@ func newNetTunDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMod } // GetFile implements fs.InodeOperations.GetFile. -func (iops *netTunInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) { +func (*netTunInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) { return fs.NewFile(ctx, d, flags, &netTunFileOperations{}), nil } @@ -80,12 +83,12 @@ type netTunFileOperations struct { var _ fs.FileOperations = (*netTunFileOperations)(nil) // Release implements fs.FileOperations.Release. -func (fops *netTunFileOperations) Release(ctx context.Context) { - fops.device.Release(ctx) +func (n *netTunFileOperations) Release(ctx context.Context) { + n.device.Release(ctx) } // Ioctl implements fs.FileOperations.Ioctl. -func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { +func (n *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { request := args[1].Uint() data := args[2].Pointer() @@ -109,16 +112,25 @@ func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io u return 0, err } flags := usermem.ByteOrder.Uint16(req.Data[:]) - return 0, fops.device.SetIff(stack.Stack, req.Name(), flags) + created, err := n.device.SetIff(stack.Stack, req.Name(), flags) + if err == nil && created { + // Always start with an ARP address for interfaces so they can handle ARP + // packets. + nicID := n.device.NICID() + if err := stack.Stack.AddAddress(nicID, arp.ProtocolNumber, arp.ProtocolAddress); err != nil { + panic(fmt.Sprintf("failed to add ARP address after creating new TUN/TAP interface with ID = %d", nicID)) + } + } + return 0, err case linux.TUNGETIFF: var req linux.IFReq - copy(req.IFName[:], fops.device.Name()) + copy(req.IFName[:], n.device.Name()) // Linux adds IFF_NOFILTER (the same value as IFF_NO_PI unfortunately) when // there is no sk_filter. See __tun_chr_ioctl() in net/drivers/tun.c. - flags := fops.device.Flags() | linux.IFF_NOFILTER + flags := n.device.Flags() | linux.IFF_NOFILTER usermem.ByteOrder.PutUint16(req.Data[:], flags) _, err := req.CopyOut(t, data) @@ -130,41 +142,41 @@ func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io u } // Write implements fs.FileOperations.Write. -func (fops *netTunFileOperations) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) { +func (n *netTunFileOperations) Write(ctx context.Context, file *fs.File, src usermem.IOSequence, offset int64) (int64, error) { data := make([]byte, src.NumBytes()) if _, err := src.CopyIn(ctx, data); err != nil { return 0, err } - return fops.device.Write(data) + return n.device.Write(data) } // Read implements fs.FileOperations.Read. -func (fops *netTunFileOperations) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) { - data, err := fops.device.Read() +func (n *netTunFileOperations) Read(ctx context.Context, file *fs.File, dst usermem.IOSequence, offset int64) (int64, error) { + data, err := n.device.Read() if err != nil { return 0, err } - n, err := dst.CopyOut(ctx, data) - if n > 0 && n < len(data) { + bytesCopied, err := dst.CopyOut(ctx, data) + if bytesCopied > 0 && bytesCopied < len(data) { // Not an error for partial copying. Packet truncated. err = nil } - return int64(n), err + return int64(bytesCopied), err } // Readiness implements watier.Waitable.Readiness. -func (fops *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask { - return fops.device.Readiness(mask) +func (n *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask { + return n.device.Readiness(mask) } // EventRegister implements watier.Waitable.EventRegister. -func (fops *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) { - fops.device.EventRegister(e, mask) +func (n *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + n.device.EventRegister(e, mask) } // EventUnregister implements watier.Waitable.EventUnregister. -func (fops *netTunFileOperations) EventUnregister(e *waiter.Entry) { - fops.device.EventUnregister(e) +func (n *netTunFileOperations) EventUnregister(e *waiter.Entry) { + n.device.EventUnregister(e) } // isNetTunSupported returns whether /dev/net/tun device is supported for s. -- cgit v1.2.3