1 files changed, 204 insertions, 0 deletions
diff --git a/pkg/sentry/fs/tmpfs/tmpfs.go b/pkg/sentry/fs/tmpfs/tmpfs.go
new file mode 100644
index 000000000..1cc7ae491
--- /dev/null
+++ b/pkg/sentry/fs/tmpfs/tmpfs.go
@@ -0,0 +1,204 @@
+// Copyright 2018 Google Inc.
+//
+// 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 is a filesystem implementation backed by memory.
+package tmpfs
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/context"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/pipe"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usage"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/unix"
+)
+
+var fsInfo = fs.Info{
+	Type: linux.TMPFS_MAGIC,
+
+	// TODO: allow configuring a tmpfs size and enforce it.
+	TotalBlocks: 0,
+	FreeBlocks:  0,
+}
+
+// rename implements fs.InodeOperations.Rename for tmpfs nodes.
+func rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
+	op, ok := oldParent.InodeOperations.(*Dir)
+	if !ok {
+		return ramfs.ErrCrossDevice
+	}
+	np, ok := newParent.InodeOperations.(*Dir)
+	if !ok {
+		return ramfs.ErrCrossDevice
+	}
+	return ramfs.Rename(ctx, &op.Dir, oldName, &np.Dir, newName)
+}
+
+// Dir is a directory.
+type Dir struct {
+	ramfs.Dir
+
+	// platform is used to allocate storage for tmpfs Files.
+	platform platform.Platform
+}
+
+// NewDir returns a new directory.
+func NewDir(ctx context.Context, contents map[string]*fs.Inode, owner fs.FileOwner, perms fs.FilePermissions, msrc *fs.MountSource, platform platform.Platform) *fs.Inode {
+	d := &Dir{platform: platform}
+	d.InitDir(ctx, contents, owner, perms)
+
+	// Manually set the CreateOps.
+	d.CreateOps = d.newCreateOps()
+
+	return fs.NewInode(d, msrc, fs.StableAttr{
+		DeviceID:  tmpfsDevice.DeviceID(),
+		InodeID:   tmpfsDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+		Type:      fs.Directory,
+	})
+}
+
+// afterLoad is invoked by stateify.
+func (d *Dir) afterLoad() {
+	// Per NewDir, manually set the CreateOps.
+	d.Dir.CreateOps = d.newCreateOps()
+}
+
+// newCreateOps builds the custom CreateOps for this Dir.
+func (d *Dir) newCreateOps() *ramfs.CreateOps {
+	return &ramfs.CreateOps{
+		NewDir: func(ctx context.Context, dir *fs.Inode, perms fs.FilePermissions) (*fs.Inode, error) {
+			return NewDir(ctx, nil, fs.FileOwnerFromContext(ctx), perms, dir.MountSource, d.platform), nil
+		},
+		NewFile: func(ctx context.Context, dir *fs.Inode, perms fs.FilePermissions) (*fs.Inode, error) {
+			uattr := fs.WithCurrentTime(ctx, fs.UnstableAttr{
+				Owner: fs.FileOwnerFromContext(ctx),
+				Perms: perms,
+				// Always start unlinked.
+				Links: 0,
+			})
+			iops := NewInMemoryFile(ctx, usage.Tmpfs, uattr, d.platform)
+			return fs.NewInode(iops, dir.MountSource, fs.StableAttr{
+				DeviceID:  tmpfsDevice.DeviceID(),
+				InodeID:   tmpfsDevice.NextIno(),
+				BlockSize: usermem.PageSize,
+				Type:      fs.RegularFile,
+			}), nil
+		},
+		NewSymlink: func(ctx context.Context, dir *fs.Inode, target string) (*fs.Inode, error) {
+			return NewSymlink(ctx, target, fs.FileOwnerFromContext(ctx), dir.MountSource), nil
+		},
+		NewBoundEndpoint: func(ctx context.Context, dir *fs.Inode, socket unix.BoundEndpoint, perms fs.FilePermissions) (*fs.Inode, error) {
+			return NewSocket(ctx, socket, fs.FileOwnerFromContext(ctx), perms, dir.MountSource), nil
+		},
+		NewFifo: func(ctx context.Context, dir *fs.Inode, perms fs.FilePermissions) (*fs.Inode, error) {
+			return NewFifo(ctx, fs.FileOwnerFromContext(ctx), perms, dir.MountSource), nil
+		},
+	}
+}
+
+// Rename implements fs.InodeOperations.Rename.
+func (d *Dir) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
+	return rename(ctx, oldParent, oldName, newParent, newName)
+}
+
+// StatFS implments fs.InodeOperations.StatFS.
+func (*Dir) StatFS(context.Context) (fs.Info, error) {
+	return fsInfo, nil
+}
+
+// Symlink is a symlink.
+type Symlink struct {
+	ramfs.Symlink
+}
+
+// NewSymlink returns a new symlink with the provided permissions.
+func NewSymlink(ctx context.Context, target string, owner fs.FileOwner, msrc *fs.MountSource) *fs.Inode {
+	s := &Symlink{}
+	s.InitSymlink(ctx, owner, target)
+	return fs.NewInode(s, msrc, fs.StableAttr{
+		DeviceID:  tmpfsDevice.DeviceID(),
+		InodeID:   tmpfsDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+		Type:      fs.Symlink,
+	})
+}
+
+// Rename implements fs.InodeOperations.Rename.
+func (s *Symlink) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
+	return rename(ctx, oldParent, oldName, newParent, newName)
+}
+
+// StatFS returns the tmpfs info.
+func (s *Symlink) StatFS(context.Context) (fs.Info, error) {
+	return fsInfo, nil
+}
+
+// Socket is a socket.
+type Socket struct {
+	ramfs.Socket
+}
+
+// NewSocket returns a new socket with the provided permissions.
+func NewSocket(ctx context.Context, socket unix.BoundEndpoint, owner fs.FileOwner, perms fs.FilePermissions, msrc *fs.MountSource) *fs.Inode {
+	s := &Socket{}
+	s.InitSocket(ctx, socket, owner, perms)
+	return fs.NewInode(s, msrc, fs.StableAttr{
+		DeviceID:  tmpfsDevice.DeviceID(),
+		InodeID:   tmpfsDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+		Type:      fs.Socket,
+	})
+}
+
+// Rename implements fs.InodeOperations.Rename.
+func (s *Socket) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
+	return rename(ctx, oldParent, oldName, newParent, newName)
+}
+
+// StatFS returns the tmpfs info.
+func (s *Socket) StatFS(context.Context) (fs.Info, error) {
+	return fsInfo, nil
+}
+
+// Fifo is a tmpfs named pipe.
+type Fifo struct {
+	ramfs.Entry
+}
+
+// NewFifo creates a new named pipe.
+func NewFifo(ctx context.Context, owner fs.FileOwner, perms fs.FilePermissions, msrc *fs.MountSource) *fs.Inode {
+	f := &Fifo{}
+	f.InitEntry(ctx, owner, perms)
+	iops := pipe.NewInodeOperations(f, pipe.NewPipe(ctx, true /* isNamed */, pipe.DefaultPipeSize, usermem.PageSize))
+	return fs.NewInode(iops, msrc, fs.StableAttr{
+		DeviceID:  tmpfsDevice.DeviceID(),
+		InodeID:   tmpfsDevice.NextIno(),
+		BlockSize: usermem.PageSize,
+		Type:      fs.Pipe,
+	})
+}
+
+// Rename implements fs.InodeOperations.Rename.
+func (f *Fifo) Rename(ctx context.Context, oldParent *fs.Inode, oldName string, newParent *fs.Inode, newName string) error {
+	return rename(ctx, oldParent, oldName, newParent, newName)
+}
+
+// StatFS returns the tmpfs info.
+func (*Fifo) StatFS(context.Context) (fs.Info, error) {
+	return fsInfo, nil
+}