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-rw-r--r--pkg/sentry/fs/ext/BUILD1
-rw-r--r--pkg/sentry/fs/ext/dentry.go9
-rw-r--r--pkg/sentry/fs/ext/disklayout/inode.go6
-rw-r--r--pkg/sentry/fs/ext/ext.go7
-rw-r--r--pkg/sentry/fs/ext/ext_test.go85
5 files changed, 107 insertions, 1 deletions
diff --git a/pkg/sentry/fs/ext/BUILD b/pkg/sentry/fs/ext/BUILD
index 7028b3f78..e660e545d 100644
--- a/pkg/sentry/fs/ext/BUILD
+++ b/pkg/sentry/fs/ext/BUILD
@@ -44,6 +44,7 @@ go_test(
"//pkg/sentry/context",
"//pkg/sentry/context/contexttest",
"//pkg/sentry/fs/ext/disklayout",
+ "//pkg/sentry/kernel/auth",
"//pkg/sentry/vfs",
"//runsc/test/testutil",
"@com_github_google_go-cmp//cmp:go_default_library",
diff --git a/pkg/sentry/fs/ext/dentry.go b/pkg/sentry/fs/ext/dentry.go
index 07be99a84..054fb42b6 100644
--- a/pkg/sentry/fs/ext/dentry.go
+++ b/pkg/sentry/fs/ext/dentry.go
@@ -31,6 +31,15 @@ type dentry struct {
// Compiles only if dentry implements vfs.DentryImpl.
var _ vfs.DentryImpl = (*dentry)(nil)
+// newDentry is the dentry constructor.
+func newDentry(in *inode) *dentry {
+ d := &dentry{
+ inode: in,
+ }
+ d.vfsd.Init(d)
+ return d
+}
+
// IncRef implements vfs.DentryImpl.IncRef.
func (d *dentry) IncRef(vfsfs *vfs.Filesystem) {
d.inode.incRef()
diff --git a/pkg/sentry/fs/ext/disklayout/inode.go b/pkg/sentry/fs/ext/disklayout/inode.go
index 9ab9a4988..88ae913f5 100644
--- a/pkg/sentry/fs/ext/disklayout/inode.go
+++ b/pkg/sentry/fs/ext/disklayout/inode.go
@@ -20,6 +20,12 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel/time"
)
+// Special inodes. See https://www.kernel.org/doc/html/latest/filesystems/ext4/overview.html#special-inodes.
+const (
+ // RootDirInode is the inode number of the root directory inode.
+ RootDirInode = 2
+)
+
// The Inode interface must be implemented by structs representing ext inodes.
// The inode stores all the metadata pertaining to the file (except for the
// file name which is held by the directory entry). It does NOT expose all
diff --git a/pkg/sentry/fs/ext/ext.go b/pkg/sentry/fs/ext/ext.go
index c8b554f4d..2604169de 100644
--- a/pkg/sentry/fs/ext/ext.go
+++ b/pkg/sentry/fs/ext/ext.go
@@ -131,7 +131,12 @@ func (fstype filesystemType) NewFilesystem(ctx context.Context, creds *auth.Cred
return nil, nil, err
}
- return &fs.vfsfs, nil, nil
+ rootInode, err := fs.getOrCreateInode(disklayout.RootDirInode)
+ if err != nil {
+ return nil, nil, err
+ }
+
+ return &fs.vfsfs, &newDentry(rootInode).vfsd, nil
}
// getOrCreateInode gets the inode corresponding to the inode number passed in.
diff --git a/pkg/sentry/fs/ext/ext_test.go b/pkg/sentry/fs/ext/ext_test.go
index f92e77450..ee7f7907c 100644
--- a/pkg/sentry/fs/ext/ext_test.go
+++ b/pkg/sentry/fs/ext/ext_test.go
@@ -25,6 +25,7 @@ import (
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
"gvisor.dev/gvisor/pkg/sentry/fs/ext/disklayout"
+ "gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/runsc/test/testutil"
@@ -82,6 +83,90 @@ func setUp(t *testing.T, imagePath string) (context.Context, *vfs.Filesystem, *v
return mockCtx, fs, d, tearDown, nil
}
+// TestRootDir tests that the root directory inode is correctly initialized and
+// returned from setUp.
+func TestRootDir(t *testing.T) {
+ type inodeProps struct {
+ Mode linux.FileMode
+ UID auth.KUID
+ GID auth.KGID
+ Size uint64
+ InodeSize uint16
+ Links uint16
+ Flags disklayout.InodeFlags
+ }
+
+ type rootDirTest struct {
+ name string
+ image string
+ wantInode inodeProps
+ }
+
+ tests := []rootDirTest{
+ {
+ name: "ext4 root dir",
+ image: ext4ImagePath,
+ wantInode: inodeProps{
+ Mode: linux.ModeDirectory | 0755,
+ Size: 0x400,
+ InodeSize: 0x80,
+ Links: 3,
+ Flags: disklayout.InodeFlags{Extents: true},
+ },
+ },
+ {
+ name: "ext3 root dir",
+ image: ext3ImagePath,
+ wantInode: inodeProps{
+ Mode: linux.ModeDirectory | 0755,
+ Size: 0x400,
+ InodeSize: 0x80,
+ Links: 3,
+ },
+ },
+ {
+ name: "ext2 root dir",
+ image: ext2ImagePath,
+ wantInode: inodeProps{
+ Mode: linux.ModeDirectory | 0755,
+ Size: 0x400,
+ InodeSize: 0x80,
+ Links: 3,
+ },
+ },
+ }
+
+ for _, test := range tests {
+ t.Run(test.name, func(t *testing.T) {
+ _, _, vfsd, tearDown, err := setUp(t, test.image)
+ if err != nil {
+ t.Fatalf("setUp failed: %v", err)
+ }
+ defer tearDown()
+
+ d, ok := vfsd.Impl().(*dentry)
+ if !ok {
+ t.Fatalf("ext dentry of incorrect type: %T", vfsd.Impl())
+ }
+
+ // Offload inode contents into local structs for comparison.
+ gotInode := inodeProps{
+ Mode: d.inode.diskInode.Mode(),
+ UID: d.inode.diskInode.UID(),
+ GID: d.inode.diskInode.GID(),
+ Size: d.inode.diskInode.Size(),
+ InodeSize: d.inode.diskInode.InodeSize(),
+ Links: d.inode.diskInode.LinksCount(),
+ Flags: d.inode.diskInode.Flags(),
+ }
+
+ if diff := cmp.Diff(gotInode, test.wantInode); diff != "" {
+ t.Errorf("inode mismatch (-want +got):\n%s", diff)
+ }
+ })
+ }
+}
+
// TestFilesystemInit tests that the filesystem superblock and block group
// descriptors are correctly read in and initialized.
func TestFilesystemInit(t *testing.T) {