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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 fuse
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/devtmpfs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
)
const fuseDevMinor = 229
// fuseDevice implements vfs.Device for /dev/fuse.
type fuseDevice struct{}
// Open implements vfs.Device.Open.
func (fuseDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
if !kernel.FUSEEnabled {
return nil, syserror.ENOENT
}
var fd DeviceFD
if err := fd.vfsfd.Init(&fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{
UseDentryMetadata: true,
}); err != nil {
return nil, err
}
return &fd.vfsfd, nil
}
// DeviceFD implements vfs.FileDescriptionImpl for /dev/fuse.
type DeviceFD struct {
vfsfd vfs.FileDescription
vfs.FileDescriptionDefaultImpl
vfs.DentryMetadataFileDescriptionImpl
vfs.NoLockFD
// mounted specifies whether a FUSE filesystem was mounted using the DeviceFD.
mounted bool
// TODO(gvisor.dev/issue/2987): Add all the data structures needed to enqueue
// and deque requests, control synchronization and establish communication
// between the FUSE kernel module and the /dev/fuse character device.
}
// Release implements vfs.FileDescriptionImpl.Release.
func (fd *DeviceFD) Release() {}
// PRead implements vfs.FileDescriptionImpl.PRead.
func (fd *DeviceFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
// Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted.
if !fd.mounted {
return 0, syserror.EPERM
}
return 0, syserror.ENOSYS
}
// Read implements vfs.FileDescriptionImpl.Read.
func (fd *DeviceFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
// Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted.
if !fd.mounted {
return 0, syserror.EPERM
}
return 0, syserror.ENOSYS
}
// PWrite implements vfs.FileDescriptionImpl.PWrite.
func (fd *DeviceFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
// Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted.
if !fd.mounted {
return 0, syserror.EPERM
}
return 0, syserror.ENOSYS
}
// Write implements vfs.FileDescriptionImpl.Write.
func (fd *DeviceFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
// Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted.
if !fd.mounted {
return 0, syserror.EPERM
}
return 0, syserror.ENOSYS
}
// Seek implements vfs.FileDescriptionImpl.Seek.
func (fd *DeviceFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
// Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted.
if !fd.mounted {
return 0, syserror.EPERM
}
return 0, syserror.ENOSYS
}
// Register registers the FUSE device with vfsObj.
func Register(vfsObj *vfs.VirtualFilesystem) error {
if err := vfsObj.RegisterDevice(vfs.CharDevice, linux.MISC_MAJOR, fuseDevMinor, fuseDevice{}, &vfs.RegisterDeviceOptions{
GroupName: "misc",
}); err != nil {
return err
}
return nil
}
// CreateDevtmpfsFile creates a device special file in devtmpfs.
func CreateDevtmpfsFile(ctx context.Context, dev *devtmpfs.Accessor) error {
if err := dev.CreateDeviceFile(ctx, "fuse", vfs.CharDevice, linux.MISC_MAJOR, fuseDevMinor, 0666 /* mode */); err != nil {
return err
}
return nil
}
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