Implement FUSE_MKDIR

Fixes #3392

4 files changed, 114 insertions, 3 deletions

diff --git a/pkg/abi/linux/fuse.go b/pkg/abi/linux/fuse.go
index 5de1433d7..4ef0ab9a7 100644
--- a/pkg/abi/linux/fuse.go
+++ b/pkg/abi/linux/fuse.go
@@ -494,3 +494,41 @@ func (r *FUSEEmptyIn) MarshalUnsafe(buf []byte) {}
 func (r *FUSEEmptyIn) SizeBytes() int {
 	return 0
 }
+
+// FUSEMkdirMeta contains all the static fields of FUSEMkdirIn,
+// which is used for FUSE_MKDIR.
+//
+// +marshal
+type FUSEMkdirMeta struct {
+	// Mode of the directory of create.
+	Mode uint32
+
+	// Umask is the user file creation mask.
+	Umask uint32
+}
+
+// FUSEMkdirIn contains all the arguments sent by the kernel
+// to the daemon, to create a new directory.
+//
+// Dynamically-sized objects cannot be marshalled.
+type FUSEMkdirIn struct {
+	marshal.StubMarshallable
+
+	// MkdirMeta contains Mode and Umask of the directory to create.
+	MkdirMeta FUSEMkdirMeta
+
+	// Name of the directory to create.
+	Name string
+}
+
+// MarshalUnsafe serializes r.MkdirMeta and r.Name to the dst buffer.
+func (r *FUSEMkdirIn) MarshalUnsafe(buf []byte) {
+	r.MkdirMeta.MarshalUnsafe(buf[:r.MkdirMeta.SizeBytes()])
+	copy(buf[r.MkdirMeta.SizeBytes():], r.Name)
+}
+
+// SizeBytes is the size of the memory representation of FUSEMkdirIn.
+// 1 extra byte for null-terminated Name string.
+func (r *FUSEMkdirIn) SizeBytes() int {
+	return r.MkdirMeta.SizeBytes() + len(r.Name) + 1
+}
diff --git a/pkg/sentry/fsimpl/fuse/BUILD b/pkg/sentry/fsimpl/fuse/BUILD
index d1671e576..2d9350d57 100644
--- a/pkg/sentry/fsimpl/fuse/BUILD
+++ b/pkg/sentry/fsimpl/fuse/BUILD
@@ -31,6 +31,7 @@ go_library(
     srcs = [
         "connection.go",
         "dev.go",
+        "directory.go",
         "file.go",
         "fusefs.go",
         "init.go",
diff --git a/pkg/sentry/fsimpl/fuse/directory.go b/pkg/sentry/fsimpl/fuse/directory.go
new file mode 100644
index 000000000..44d41712a
--- /dev/null
+++ b/pkg/sentry/fsimpl/fuse/directory.go
@@ -0,0 +1,51 @@
+// 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/context"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
+)
+
+type directoryFD struct {
+	fileDescription
+}
+
+// Allocate implements directoryFD.Allocate.
+func (directoryFD) Allocate(ctx context.Context, mode, offset, length uint64) error {
+	return syserror.EISDIR
+}
+
+// PRead implements FileDescriptionImpl.PRead.
+func (directoryFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
+	return 0, syserror.EISDIR
+}
+
+// Read implements FileDescriptionImpl.Read.
+func (directoryFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
+	return 0, syserror.EISDIR
+}
+
+// PWrite implements FileDescriptionImpl.PWrite.
+func (directoryFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
+	return 0, syserror.EISDIR
+}
+
+// Write implements FileDescriptionImpl.Write.
+func (directoryFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
+	return 0, syserror.EISDIR
+}
diff --git a/pkg/sentry/fsimpl/fuse/fusefs.go b/pkg/sentry/fsimpl/fuse/fusefs.go
index 8db337a2e..4dc8ef993 100644
--- a/pkg/sentry/fsimpl/fuse/fusefs.go
+++ b/pkg/sentry/fsimpl/fuse/fusefs.go
@@ -262,8 +262,17 @@ func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentr
 		return nil, syserror.EOVERFLOW
 	}
 
-	// FOPEN_KEEP_CACHE is the defualt flag for noOpen.
-	fd := fileDescription{OpenFlag: linux.FOPEN_KEEP_CACHE}
+	var fd *fileDescription
+	var fdImpl vfs.FileDescriptionImpl
+	if isDir {
+		directoryFD := &directoryFD{}
+		fd = &(directoryFD.fileDescription)
+		fdImpl = directoryFD
+	} else {
+		// FOPEN_KEEP_CACHE is the defualt flag for noOpen.
+		fd = &fileDescription{OpenFlag: linux.FOPEN_KEEP_CACHE}
+		fdImpl = fd
+	}
 	// Only send open request when FUSE server support open or is opening a directory.
 	if !i.fs.conn.noOpen || isDir {
 		kernelTask := kernel.TaskFromContext(ctx)
@@ -330,7 +339,7 @@ func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentr
 		i.attributeTime = 0
 	}
 
-	if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), vfsd, fdOptions); err != nil {
+	if err := fd.vfsfd.Init(fdImpl, opts.Flags, rp.Mount(), vfsd, fdOptions); err != nil {
 		return nil, err
 	}
 	return &fd.vfsfd, nil
@@ -374,6 +383,18 @@ func (i *inode) NewSymlink(ctx context.Context, name, target string) (*vfs.Dentr
 	return i.newEntry(ctx, name, linux.S_IFLNK, linux.FUSE_SYMLINK, &in)
 }
 
+// NewDir implements kernfs.Inode.NewDir.
+func (i *inode) NewDir(ctx context.Context, name string, opts vfs.MkdirOptions) (*vfs.Dentry, error) {
+	in := linux.FUSEMkdirIn{
+		MkdirMeta: linux.FUSEMkdirMeta{
+			Mode:  uint32(opts.Mode),
+			Umask: uint32(kernel.TaskFromContext(ctx).FSContext().Umask()),
+		},
+		Name: name,
+	}
+	return i.newEntry(ctx, name, linux.S_IFDIR, linux.FUSE_MKDIR, &in)
+}
+
 // newEntry calls FUSE server for entry creation and allocates corresponding entry according to response.
 // Shared by FUSE_MKNOD, FUSE_MKDIR, FUSE_SYMLINK, FUSE_LINK and FUSE_LOOKUP.
 func (i *inode) newEntry(ctx context.Context, name string, fileType linux.FileMode, opcode linux.FUSEOpcode, payload marshal.Marshallable) (*vfs.Dentry, error) {