3 files changed, 201 insertions, 3 deletions
diff --git a/pkg/sentry/fs/dev/dev.go b/pkg/sentry/fs/dev/dev.go
index 35bd23991..7e66c29b0 100644
--- a/pkg/sentry/fs/dev/dev.go
+++ b/pkg/sentry/fs/dev/dev.go
@@ -66,8 +66,8 @@ func newMemDevice(ctx context.Context, iops fs.InodeOperations, msrc *fs.MountSo
 	})
 }
 
-func newDirectory(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
-	iops := ramfs.NewDir(ctx, nil, fs.RootOwner, fs.FilePermsFromMode(0555))
+func newDirectory(ctx context.Context, contents map[string]*fs.Inode, msrc *fs.MountSource) *fs.Inode {
+	iops := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
 	return fs.NewInode(ctx, iops, msrc, fs.StableAttr{
 		DeviceID:  devDevice.DeviceID(),
 		InodeID:   devDevice.NextIno(),
@@ -111,7 +111,7 @@ func New(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
 		// A devpts is typically mounted at /dev/pts to provide
 		// pseudoterminal support. Place an empty directory there for
 		// the devpts to be mounted over.
-		"pts": newDirectory(ctx, msrc),
+		"pts": newDirectory(ctx, nil, msrc),
 		// Similarly, applications expect a ptmx device at /dev/ptmx
 		// connected to the terminals provided by /dev/pts/. Rather
 		// than creating a device directly (which requires a hairy
@@ -124,6 +124,10 @@ func New(ctx context.Context, msrc *fs.MountSource) *fs.Inode {
 		"ptmx": newSymlink(ctx, "pts/ptmx", msrc),
 
 		"tty": newCharacterDevice(ctx, newTTYDevice(ctx, fs.RootOwner, 0666), msrc, ttyDevMajor, ttyDevMinor),
+
+		"net": newDirectory(ctx, map[string]*fs.Inode{
+			"tun": newCharacterDevice(ctx, newNetTunDevice(ctx, fs.RootOwner, 0666), msrc, netTunDevMajor, netTunDevMinor),
+		}, msrc),
 	}
 
 	iops := ramfs.NewDir(ctx, contents, fs.RootOwner, fs.FilePermsFromMode(0555))
diff --git a/pkg/sentry/fs/dev/dev_state_autogen.go b/pkg/sentry/fs/dev/dev_state_autogen.go
index f381b2f80..272f02672 100755
--- a/pkg/sentry/fs/dev/dev_state_autogen.go
+++ b/pkg/sentry/fs/dev/dev_state_autogen.go
@@ -35,6 +35,28 @@ func (x *fullFileOperations) afterLoad() {}
 func (x *fullFileOperations) load(m state.Map) {
 }
 
+func (x *netTunInodeOperations) beforeSave() {}
+func (x *netTunInodeOperations) save(m state.Map) {
+	x.beforeSave()
+	m.Save("InodeSimpleAttributes", &x.InodeSimpleAttributes)
+}
+
+func (x *netTunInodeOperations) afterLoad() {}
+func (x *netTunInodeOperations) load(m state.Map) {
+	m.Load("InodeSimpleAttributes", &x.InodeSimpleAttributes)
+}
+
+func (x *netTunFileOperations) beforeSave() {}
+func (x *netTunFileOperations) save(m state.Map) {
+	x.beforeSave()
+	m.Save("device", &x.device)
+}
+
+func (x *netTunFileOperations) afterLoad() {}
+func (x *netTunFileOperations) load(m state.Map) {
+	m.Load("device", &x.device)
+}
+
 func (x *nullDevice) beforeSave() {}
 func (x *nullDevice) save(m state.Map) {
 	x.beforeSave()
@@ -119,6 +141,8 @@ func init() {
 	state.Register("pkg/sentry/fs/dev.filesystem", (*filesystem)(nil), state.Fns{Save: (*filesystem).save, Load: (*filesystem).load})
 	state.Register("pkg/sentry/fs/dev.fullDevice", (*fullDevice)(nil), state.Fns{Save: (*fullDevice).save, Load: (*fullDevice).load})
 	state.Register("pkg/sentry/fs/dev.fullFileOperations", (*fullFileOperations)(nil), state.Fns{Save: (*fullFileOperations).save, Load: (*fullFileOperations).load})
+	state.Register("pkg/sentry/fs/dev.netTunInodeOperations", (*netTunInodeOperations)(nil), state.Fns{Save: (*netTunInodeOperations).save, Load: (*netTunInodeOperations).load})
+	state.Register("pkg/sentry/fs/dev.netTunFileOperations", (*netTunFileOperations)(nil), state.Fns{Save: (*netTunFileOperations).save, Load: (*netTunFileOperations).load})
 	state.Register("pkg/sentry/fs/dev.nullDevice", (*nullDevice)(nil), state.Fns{Save: (*nullDevice).save, Load: (*nullDevice).load})
 	state.Register("pkg/sentry/fs/dev.nullFileOperations", (*nullFileOperations)(nil), state.Fns{Save: (*nullFileOperations).save, Load: (*nullFileOperations).load})
 	state.Register("pkg/sentry/fs/dev.zeroDevice", (*zeroDevice)(nil), state.Fns{Save: (*zeroDevice).save, Load: (*zeroDevice).load})
diff --git a/pkg/sentry/fs/dev/net_tun.go b/pkg/sentry/fs/dev/net_tun.go
new file mode 100755
index 000000000..755644488
--- /dev/null
+++ b/pkg/sentry/fs/dev/net_tun.go
@@ -0,0 +1,170 @@
+// Copyright 2020 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 dev
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/fs"
+	"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/socket/netstack"
+	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/tcpip/link/tun"
+	"gvisor.dev/gvisor/pkg/usermem"
+	"gvisor.dev/gvisor/pkg/waiter"
+)
+
+const (
+	netTunDevMajor = 10
+	netTunDevMinor = 200
+)
+
+// +stateify savable
+type netTunInodeOperations struct {
+	fsutil.InodeGenericChecker       `state:"nosave"`
+	fsutil.InodeNoExtendedAttributes `state:"nosave"`
+	fsutil.InodeNoopAllocate         `state:"nosave"`
+	fsutil.InodeNoopRelease          `state:"nosave"`
+	fsutil.InodeNoopTruncate         `state:"nosave"`
+	fsutil.InodeNoopWriteOut         `state:"nosave"`
+	fsutil.InodeNotDirectory         `state:"nosave"`
+	fsutil.InodeNotMappable          `state:"nosave"`
+	fsutil.InodeNotSocket            `state:"nosave"`
+	fsutil.InodeNotSymlink           `state:"nosave"`
+	fsutil.InodeVirtual              `state:"nosave"`
+
+	fsutil.InodeSimpleAttributes
+}
+
+var _ fs.InodeOperations = (*netTunInodeOperations)(nil)
+
+func newNetTunDevice(ctx context.Context, owner fs.FileOwner, mode linux.FileMode) *netTunInodeOperations {
+	return &netTunInodeOperations{
+		InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(mode), linux.TMPFS_MAGIC),
+	}
+}
+
+// GetFile implements fs.InodeOperations.GetFile.
+func (iops *netTunInodeOperations) GetFile(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
+	return fs.NewFile(ctx, d, flags, &netTunFileOperations{}), nil
+}
+
+// +stateify savable
+type netTunFileOperations struct {
+	fsutil.FileNoSeek               `state:"nosave"`
+	fsutil.FileNoMMap               `state:"nosave"`
+	fsutil.FileNoSplice             `state:"nosave"`
+	fsutil.FileNoopFlush            `state:"nosave"`
+	fsutil.FileNoopFsync            `state:"nosave"`
+	fsutil.FileNotDirReaddir        `state:"nosave"`
+	fsutil.FileUseInodeUnstableAttr `state:"nosave"`
+
+	device tun.Device
+}
+
+var _ fs.FileOperations = (*netTunFileOperations)(nil)
+
+// Release implements fs.FileOperations.Release.
+func (fops *netTunFileOperations) Release() {
+	fops.device.Release()
+}
+
+// Ioctl implements fs.FileOperations.Ioctl.
+func (fops *netTunFileOperations) Ioctl(ctx context.Context, file *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
+	request := args[1].Uint()
+	data := args[2].Pointer()
+
+	switch request {
+	case linux.TUNSETIFF:
+		t := kernel.TaskFromContext(ctx)
+		if t == nil {
+			panic("Ioctl should be called from a task context")
+		}
+		if !t.HasCapability(linux.CAP_NET_ADMIN) {
+			return 0, syserror.EPERM
+		}
+		stack, ok := t.NetworkContext().(*netstack.Stack)
+		if !ok {
+			return 0, syserror.EINVAL
+		}
+
+		var req linux.IFReq
+		if _, err := usermem.CopyObjectIn(ctx, io, data, &req, usermem.IOOpts{
+			AddressSpaceActive: true,
+		}); err != nil {
+			return 0, err
+		}
+		flags := usermem.ByteOrder.Uint16(req.Data[:])
+		return 0, fops.device.SetIff(stack.Stack, req.Name(), flags)
+
+	case linux.TUNGETIFF:
+		var req linux.IFReq
+
+		copy(req.IFName[:], fops.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
+		usermem.ByteOrder.PutUint16(req.Data[:], flags)
+
+		_, err := usermem.CopyObjectOut(ctx, io, data, &req, usermem.IOOpts{
+			AddressSpaceActive: true,
+		})
+		return 0, err
+
+	default:
+		return 0, syserror.ENOTTY
+	}
+}
+
+// Write implements fs.FileOperations.Write.
+func (fops *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)
+}
+
+// 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()
+	if err != nil {
+		return 0, err
+	}
+	n, err := dst.CopyOut(ctx, data)
+	if n > 0 && n < len(data) {
+		// Not an error for partial copying. Packet truncated.
+		err = nil
+	}
+	return int64(n), err
+}
+
+// Readiness implements watier.Waitable.Readiness.
+func (fops *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
+	return fops.device.Readiness(mask)
+}
+
+// EventRegister implements watier.Waitable.EventRegister.
+func (fops *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
+	fops.device.EventRegister(e, mask)
+}
+
+// EventUnregister implements watier.Waitable.EventUnregister.
+func (fops *netTunFileOperations) EventUnregister(e *waiter.Entry) {
+	fops.device.EventUnregister(e)
+}