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// 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/errors/linuxerr"
"gvisor.dev/gvisor/pkg/hostarch"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
"gvisor.dev/gvisor/pkg/sentry/inet"
"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 (*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 (n *netTunFileOperations) Release(ctx context.Context) {
n.device.Release(ctx)
}
// Ioctl implements fs.FileOperations.Ioctl.
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()
t := kernel.TaskFromContext(ctx)
if t == nil {
panic("Ioctl should be called from a task context")
}
switch request {
case linux.TUNSETIFF:
if !t.HasCapability(linux.CAP_NET_ADMIN) {
return 0, syserror.EPERM
}
stack, ok := t.NetworkContext().(*netstack.Stack)
if !ok {
return 0, linuxerr.EINVAL
}
var req linux.IFReq
if _, err := req.CopyIn(t, data); err != nil {
return 0, err
}
// Validate flags.
flags, err := netstack.LinuxToTUNFlags(hostarch.ByteOrder.Uint16(req.Data[:]))
if err != nil {
return 0, err
}
return 0, n.device.SetIff(stack.Stack, req.Name(), flags)
case linux.TUNGETIFF:
var req linux.IFReq
copy(req.IFName[:], n.device.Name())
hostarch.ByteOrder.PutUint16(req.Data[:], netstack.TUNFlagsToLinux(n.device.Flags()))
_, err := req.CopyOut(t, data)
return 0, err
default:
return 0, syserror.ENOTTY
}
}
// Write implements fs.FileOperations.Write.
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 n.device.Write(data)
}
// Read implements fs.FileOperations.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
}
bytesCopied, err := dst.CopyOut(ctx, data)
if bytesCopied > 0 && bytesCopied < len(data) {
// Not an error for partial copying. Packet truncated.
err = nil
}
return int64(bytesCopied), err
}
// Readiness implements watier.Waitable.Readiness.
func (n *netTunFileOperations) Readiness(mask waiter.EventMask) waiter.EventMask {
return n.device.Readiness(mask)
}
// EventRegister implements watier.Waitable.EventRegister.
func (n *netTunFileOperations) EventRegister(e *waiter.Entry, mask waiter.EventMask) {
n.device.EventRegister(e, mask)
}
// EventUnregister implements watier.Waitable.EventUnregister.
func (n *netTunFileOperations) EventUnregister(e *waiter.Entry) {
n.device.EventUnregister(e)
}
// isNetTunSupported returns whether /dev/net/tun device is supported for s.
func isNetTunSupported(s inet.Stack) bool {
_, ok := s.(*netstack.Stack)
return ok
}
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