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Add support for device special files to VFS2 tmpfs. 

PiperOrigin-RevId: 291471892
This commit is contained in:
Jamie Liu 2020-01-24 17:06:30 -08:00 committed by gVisor bot
parent 878bda6e19
commit 18a7e1309d
4 changed files with 88 additions and 25 deletions
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1
pkg/sentry/fsimpl/tmpfs/BUILD
View File

@ -20,6 +20,7 @@ go_library(
name = "tmpfs",
srcs = [
"dentry_list.go",
"device_file.go",
"directory.go",
"filesystem.go",
"named_pipe.go",

39
pkg/sentry/fsimpl/tmpfs/device_file.go Normal file
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@ -0,0 +1,39 @@
// 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 tmpfs
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/vfs"
)
type deviceFile struct {
inode inode
kind vfs.DeviceKind
major uint32
minor uint32
}
func (fs *filesystem) newDeviceFile(creds *auth.Credentials, mode linux.FileMode, kind vfs.DeviceKind, major, minor uint32) *inode {
file := &deviceFile{
kind: kind,
major: major,
minor: minor,
}
file.inode.init(file, fs, creds, mode)
file.inode.nlink = 1 // from parent directory
return &file.inode
}

43
pkg/sentry/fsimpl/tmpfs/filesystem.go
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@ -228,23 +228,26 @@ func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
// MknodAt implements vfs.FilesystemImpl.MknodAt.
func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error {
return fs.doCreateAt(rp, false /* dir */, func(parent *dentry, name string) error {
var childInode *inode
switch opts.Mode.FileType() {
case 0, linux.S_IFREG:
child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode))
parent.vfsd.InsertChild(&child.vfsd, name)
parent.inode.impl.(*directory).childList.PushBack(child)
return nil
childInode = fs.newRegularFile(rp.Credentials(), opts.Mode)
case linux.S_IFIFO:
child := fs.newDentry(fs.newNamedPipe(rp.Credentials(), opts.Mode))
parent.vfsd.InsertChild(&child.vfsd, name)
parent.inode.impl.(*directory).childList.PushBack(child)
return nil
case linux.S_IFBLK, linux.S_IFCHR, linux.S_IFSOCK:
childInode = fs.newNamedPipe(rp.Credentials(), opts.Mode)
case linux.S_IFBLK:
childInode = fs.newDeviceFile(rp.Credentials(), opts.Mode, vfs.BlockDevice, opts.DevMajor, opts.DevMinor)
case linux.S_IFCHR:
childInode = fs.newDeviceFile(rp.Credentials(), opts.Mode, vfs.CharDevice, opts.DevMajor, opts.DevMinor)
case linux.S_IFSOCK:
// Not yet supported.
return syserror.EPERM
default:
return syserror.EINVAL
}
child := fs.newDentry(childInode)
parent.vfsd.InsertChild(&child.vfsd, name)
parent.inode.impl.(*directory).childList.PushBack(child)
return nil
})
}
@ -264,7 +267,7 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
if err != nil {
return nil, err
}
return d.open(ctx, rp, opts.Flags, false /* afterCreate */)
return d.open(ctx, rp, &opts, false /* afterCreate */)
}
mustCreate := opts.Flags&linux.O_EXCL != 0
@ -279,7 +282,7 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
if mustCreate {
return nil, syserror.EEXIST
}
return start.open(ctx, rp, opts.Flags, false /* afterCreate */)
return start.open(ctx, rp, &opts, false /* afterCreate */)
}
afterTrailingSymlink:
parent, err := walkParentDirLocked(rp, start)
@ -313,7 +316,7 @@ afterTrailingSymlink:
child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode))
parent.vfsd.InsertChild(&child.vfsd, name)
parent.inode.impl.(*directory).childList.PushBack(child)
return child.open(ctx, rp, opts.Flags, true)
return child.open(ctx, rp, &opts, true)
}
if err != nil {
return nil, err
@ -327,11 +330,11 @@ afterTrailingSymlink:
if mustCreate {
return nil, syserror.EEXIST
}
return child.open(ctx, rp, opts.Flags, false)
return child.open(ctx, rp, &opts, false)
}
func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32, afterCreate bool) (*vfs.FileDescription, error) {
ats := vfs.AccessTypesForOpenFlags(flags)
func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions, afterCreate bool) (*vfs.FileDescription, error) {
ats := vfs.AccessTypesForOpenFlags(opts.Flags)
if !afterCreate {
if err := d.inode.checkPermissions(rp.Credentials(), ats, d.inode.isDir()); err != nil {
return nil, err
@ -340,10 +343,10 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32,
switch impl := d.inode.impl.(type) {
case *regularFile:
var fd regularFileFD
if err := fd.vfsfd.Init(&fd, flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
return nil, err
}
if flags&linux.O_TRUNC != 0 {
if opts.Flags&linux.O_TRUNC != 0 {
impl.mu.Lock()
impl.data.Truncate(0, impl.memFile)
atomic.StoreUint64(&impl.size, 0)
@ -356,7 +359,7 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32,
return nil, syserror.EISDIR
}
var fd directoryFD
if err := fd.vfsfd.Init(&fd, flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
return nil, err
}
return &fd.vfsfd, nil
@ -364,7 +367,9 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, flags uint32,
// Can't open symlinks without O_PATH (which is unimplemented).
return nil, syserror.ELOOP
case *namedPipe:
return newNamedPipeFD(ctx, impl, rp, &d.vfsd, flags)
return newNamedPipeFD(ctx, impl, rp, &d.vfsd, opts.Flags)
case *deviceFile:
return rp.VirtualFilesystem().OpenDeviceSpecialFile(ctx, rp.Mount(), &d.vfsd, impl.kind, impl.major, impl.minor, opts)
default:
panic(fmt.Sprintf("unknown inode type: %T", d.inode.impl))
}

30
pkg/sentry/fsimpl/tmpfs/tmpfs.go
View File

@ -149,6 +149,10 @@ type inode struct {
ctime int64 // nanoseconds
mtime int64 // nanoseconds
// Only meaningful for device special files.
rdevMajor uint32
rdevMinor uint32
impl interface{} // immutable
}
@ -269,6 +273,15 @@ func (i *inode) statTo(stat *linux.Statx) {
stat.Blocks = allocatedBlocksForSize(stat.Size)
case *namedPipe:
stat.Mode |= linux.S_IFIFO
case *deviceFile:
switch impl.kind {
case vfs.BlockDevice:
stat.Mode |= linux.S_IFBLK
case vfs.CharDevice:
stat.Mode |= linux.S_IFCHR
}
stat.RdevMajor = impl.major
stat.RdevMinor = impl.minor
default:
panic(fmt.Sprintf("unknown inode type: %T", i.impl))
}
@ -309,12 +322,8 @@ func (i *inode) setStat(stat linux.Statx) error {
}
case *directory:
return syserror.EISDIR
case *symlink:
return syserror.EINVAL
case *namedPipe:
// Nothing.
default:
panic(fmt.Sprintf("unknown inode type: %T", i.impl))
return syserror.EINVAL
}
}
if mask&linux.STATX_ATIME != 0 {
@ -353,13 +362,22 @@ func allocatedBlocksForSize(size uint64) uint64 {
}
func (i *inode) direntType() uint8 {
switch i.impl.(type) {
switch impl := i.impl.(type) {
case *regularFile:
return linux.DT_REG
case *directory:
return linux.DT_DIR
case *symlink:
return linux.DT_LNK
case *deviceFile:
switch impl.kind {
case vfs.BlockDevice:
return linux.DT_BLK
case vfs.CharDevice:
return linux.DT_CHR
default:
panic(fmt.Sprintf("unknown vfs.DeviceKind: %v", impl.kind))
}
default:
panic(fmt.Sprintf("unknown inode type: %T", i.impl))
}