1 files changed, 326 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_test.go b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
new file mode 100644
index 000000000..a9f671bc8
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
@@ -0,0 +1,326 @@
+// Copyright 2019 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 kernfs_test
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/sentry/contexttest"
+	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
+	"gvisor.dev/gvisor/pkg/sentry/fsimpl/testutil"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
+)
+
+const defaultMode linux.FileMode = 01777
+const staticFileContent = "This is sample content for a static test file."
+
+// RootDentryFn is a generator function for creating the root dentry of a test
+// filesystem. See newTestSystem.
+type RootDentryFn func(*auth.Credentials, *filesystem) *kernfs.Dentry
+
+// newTestSystem sets up a minimal environment for running a test, including an
+// instance of a test filesystem. Tests can control the contents of the
+// filesystem by providing an appropriate rootFn, which should return a
+// pre-populated root dentry.
+func newTestSystem(t *testing.T, rootFn RootDentryFn) *testutil.System {
+	ctx := contexttest.Context(t)
+	creds := auth.CredentialsFromContext(ctx)
+	v := &vfs.VirtualFilesystem{}
+	if err := v.Init(); err != nil {
+		t.Fatalf("VFS init: %v", err)
+	}
+	v.MustRegisterFilesystemType("testfs", &fsType{rootFn: rootFn}, &vfs.RegisterFilesystemTypeOptions{
+		AllowUserMount: true,
+	})
+	mns, err := v.NewMountNamespace(ctx, creds, "", "testfs", &vfs.GetFilesystemOptions{})
+	if err != nil {
+		t.Fatalf("Failed to create testfs root mount: %v", err)
+	}
+	return testutil.NewSystem(ctx, t, v, mns)
+}
+
+type fsType struct {
+	rootFn RootDentryFn
+}
+
+type filesystem struct {
+	kernfs.Filesystem
+}
+
+type file struct {
+	kernfs.DynamicBytesFile
+	content string
+}
+
+func (fs *filesystem) newFile(creds *auth.Credentials, content string) *kernfs.Dentry {
+	f := &file{}
+	f.content = content
+	f.DynamicBytesFile.Init(creds, fs.NextIno(), f, 0777)
+
+	d := &kernfs.Dentry{}
+	d.Init(f)
+	return d
+}
+
+func (f *file) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	fmt.Fprintf(buf, "%s", f.content)
+	return nil
+}
+
+type attrs struct {
+	kernfs.InodeAttrs
+}
+
+func (*attrs) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.SetStatOptions) error {
+	return syserror.EPERM
+}
+
+type readonlyDir struct {
+	attrs
+	kernfs.InodeNotSymlink
+	kernfs.InodeNoDynamicLookup
+	kernfs.InodeDirectoryNoNewChildren
+
+	kernfs.OrderedChildren
+	dentry kernfs.Dentry
+}
+
+func (fs *filesystem) newReadonlyDir(creds *auth.Credentials, mode linux.FileMode, contents map[string]*kernfs.Dentry) *kernfs.Dentry {
+	dir := &readonlyDir{}
+	dir.attrs.Init(creds, fs.NextIno(), linux.ModeDirectory|mode)
+	dir.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
+	dir.dentry.Init(dir)
+
+	dir.IncLinks(dir.OrderedChildren.Populate(&dir.dentry, contents))
+
+	return &dir.dentry
+}
+
+func (d *readonlyDir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
+	fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts)
+	if err != nil {
+		return nil, err
+	}
+	return fd.VFSFileDescription(), nil
+}
+
+type dir struct {
+	attrs
+	kernfs.InodeNotSymlink
+	kernfs.InodeNoDynamicLookup
+
+	fs     *filesystem
+	dentry kernfs.Dentry
+	kernfs.OrderedChildren
+}
+
+func (fs *filesystem) newDir(creds *auth.Credentials, mode linux.FileMode, contents map[string]*kernfs.Dentry) *kernfs.Dentry {
+	dir := &dir{}
+	dir.fs = fs
+	dir.attrs.Init(creds, fs.NextIno(), linux.ModeDirectory|mode)
+	dir.OrderedChildren.Init(kernfs.OrderedChildrenOptions{Writable: true})
+	dir.dentry.Init(dir)
+
+	dir.IncLinks(dir.OrderedChildren.Populate(&dir.dentry, contents))
+
+	return &dir.dentry
+}
+
+func (d *dir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
+	fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts)
+	if err != nil {
+		return nil, err
+	}
+	return fd.VFSFileDescription(), nil
+}
+
+func (d *dir) NewDir(ctx context.Context, name string, opts vfs.MkdirOptions) (*vfs.Dentry, error) {
+	creds := auth.CredentialsFromContext(ctx)
+	dir := d.fs.newDir(creds, opts.Mode, nil)
+	dirVFSD := dir.VFSDentry()
+	if err := d.OrderedChildren.Insert(name, dirVFSD); err != nil {
+		dir.DecRef()
+		return nil, err
+	}
+	d.IncLinks(1)
+	return dirVFSD, nil
+}
+
+func (d *dir) NewFile(ctx context.Context, name string, opts vfs.OpenOptions) (*vfs.Dentry, error) {
+	creds := auth.CredentialsFromContext(ctx)
+	f := d.fs.newFile(creds, "")
+	fVFSD := f.VFSDentry()
+	if err := d.OrderedChildren.Insert(name, fVFSD); err != nil {
+		f.DecRef()
+		return nil, err
+	}
+	return fVFSD, nil
+}
+
+func (*dir) NewLink(context.Context, string, kernfs.Inode) (*vfs.Dentry, error) {
+	return nil, syserror.EPERM
+}
+
+func (*dir) NewSymlink(context.Context, string, string) (*vfs.Dentry, error) {
+	return nil, syserror.EPERM
+}
+
+func (*dir) NewNode(context.Context, string, vfs.MknodOptions) (*vfs.Dentry, error) {
+	return nil, syserror.EPERM
+}
+
+func (fsType) Name() string {
+	return "kernfs"
+}
+
+func (fst fsType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opt vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
+	fs := &filesystem{}
+	fs.Init(vfsObj, &fst)
+	root := fst.rootFn(creds, fs)
+	return fs.VFSFilesystem(), root.VFSDentry(), nil
+}
+
+// -------------------- Remainder of the file are test cases --------------------
+
+func TestBasic(t *testing.T) {
+	sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
+		return fs.newReadonlyDir(creds, 0755, map[string]*kernfs.Dentry{
+			"file1": fs.newFile(creds, staticFileContent),
+		})
+	})
+	defer sys.Destroy()
+	sys.GetDentryOrDie(sys.PathOpAtRoot("file1")).DecRef()
+}
+
+func TestMkdirGetDentry(t *testing.T) {
+	sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
+		return fs.newReadonlyDir(creds, 0755, map[string]*kernfs.Dentry{
+			"dir1": fs.newDir(creds, 0755, nil),
+		})
+	})
+	defer sys.Destroy()
+
+	pop := sys.PathOpAtRoot("dir1/a new directory")
+	if err := sys.VFS.MkdirAt(sys.Ctx, sys.Creds, pop, &vfs.MkdirOptions{Mode: 0755}); err != nil {
+		t.Fatalf("MkdirAt for PathOperation %+v failed: %v", pop, err)
+	}
+	sys.GetDentryOrDie(pop).DecRef()
+}
+
+func TestReadStaticFile(t *testing.T) {
+	sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
+		return fs.newReadonlyDir(creds, 0755, map[string]*kernfs.Dentry{
+			"file1": fs.newFile(creds, staticFileContent),
+		})
+	})
+	defer sys.Destroy()
+
+	pop := sys.PathOpAtRoot("file1")
+	fd, err := sys.VFS.OpenAt(sys.Ctx, sys.Creds, pop, &vfs.OpenOptions{
+		Flags: linux.O_RDONLY,
+	})
+	if err != nil {
+		t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
+	}
+	defer fd.DecRef()
+
+	content, err := sys.ReadToEnd(fd)
+	if err != nil {
+		t.Fatalf("Read failed: %v", err)
+	}
+	if diff := cmp.Diff(staticFileContent, content); diff != "" {
+		t.Fatalf("Read returned unexpected data:\n--- want\n+++ got\n%v", diff)
+	}
+}
+
+func TestCreateNewFileInStaticDir(t *testing.T) {
+	sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
+		return fs.newReadonlyDir(creds, 0755, map[string]*kernfs.Dentry{
+			"dir1": fs.newDir(creds, 0755, nil),
+		})
+	})
+	defer sys.Destroy()
+
+	pop := sys.PathOpAtRoot("dir1/newfile")
+	opts := &vfs.OpenOptions{Flags: linux.O_CREAT | linux.O_EXCL, Mode: defaultMode}
+	fd, err := sys.VFS.OpenAt(sys.Ctx, sys.Creds, pop, opts)
+	if err != nil {
+		t.Fatalf("OpenAt(pop:%+v, opts:%+v) failed: %v", pop, opts, err)
+	}
+
+	// Close the file. The file should persist.
+	fd.DecRef()
+
+	fd, err = sys.VFS.OpenAt(sys.Ctx, sys.Creds, pop, &vfs.OpenOptions{
+		Flags: linux.O_RDONLY,
+	})
+	if err != nil {
+		t.Fatalf("OpenAt(pop:%+v) = %+v failed: %v", pop, fd, err)
+	}
+	fd.DecRef()
+}
+
+func TestDirFDReadWrite(t *testing.T) {
+	sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
+		return fs.newReadonlyDir(creds, 0755, nil)
+	})
+	defer sys.Destroy()
+
+	pop := sys.PathOpAtRoot("/")
+	fd, err := sys.VFS.OpenAt(sys.Ctx, sys.Creds, pop, &vfs.OpenOptions{
+		Flags: linux.O_RDONLY,
+	})
+	if err != nil {
+		t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
+	}
+	defer fd.DecRef()
+
+	// Read/Write should fail for directory FDs.
+	if _, err := fd.Read(sys.Ctx, usermem.BytesIOSequence([]byte{}), vfs.ReadOptions{}); err != syserror.EISDIR {
+		t.Fatalf("Read for directory FD failed with unexpected error: %v", err)
+	}
+	if _, err := fd.Write(sys.Ctx, usermem.BytesIOSequence([]byte{}), vfs.WriteOptions{}); err != syserror.EBADF {
+		t.Fatalf("Write for directory FD failed with unexpected error: %v", err)
+	}
+}
+
+func TestDirFDIterDirents(t *testing.T) {
+	sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
+		return fs.newReadonlyDir(creds, 0755, map[string]*kernfs.Dentry{
+			// Fill root with nodes backed by various inode implementations.
+			"dir1": fs.newReadonlyDir(creds, 0755, nil),
+			"dir2": fs.newDir(creds, 0755, map[string]*kernfs.Dentry{
+				"dir3": fs.newDir(creds, 0755, nil),
+			}),
+			"file1": fs.newFile(creds, staticFileContent),
+		})
+	})
+	defer sys.Destroy()
+
+	pop := sys.PathOpAtRoot("/")
+	sys.AssertAllDirentTypes(sys.ListDirents(pop), map[string]testutil.DirentType{
+		"dir1":  linux.DT_DIR,
+		"dir2":  linux.DT_DIR,
+		"file1": linux.DT_REG,
+	})
+}