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-rw-r--r--pkg/sentry/vfs/dentry.go24
-rw-r--r--pkg/sentry/vfs/file_description.go33
-rw-r--r--pkg/sentry/vfs/file_description_impl_util_test.go2
-rw-r--r--pkg/sentry/vfs/filesystem.go20
-rw-r--r--pkg/sentry/vfs/filesystem_type.go10
-rw-r--r--pkg/sentry/vfs/mount.go56
-rw-r--r--pkg/sentry/vfs/resolving_path.go8
-rw-r--r--pkg/sentry/vfs/syscalls.go2
-rw-r--r--pkg/sentry/vfs/testutil.go12
-rw-r--r--pkg/sentry/vfs/vfs.go8
10 files changed, 110 insertions, 65 deletions
diff --git a/pkg/sentry/vfs/dentry.go b/pkg/sentry/vfs/dentry.go
index 09ed5a70e..40f4c1d09 100644
--- a/pkg/sentry/vfs/dentry.go
+++ b/pkg/sentry/vfs/dentry.go
@@ -118,7 +118,7 @@ func (d *Dentry) Impl() DentryImpl {
type DentryImpl interface {
// IncRef increments the Dentry's reference count. A Dentry with a non-zero
// reference count must remain coherent with the state of the filesystem.
- IncRef(fs *Filesystem)
+ IncRef()
// TryIncRef increments the Dentry's reference count and returns true. If
// the Dentry's reference count is zero, TryIncRef may do nothing and
@@ -126,10 +126,10 @@ type DentryImpl interface {
// guarantee that the Dentry is coherent with the state of the filesystem.)
//
// TryIncRef does not require that a reference is held on the Dentry.
- TryIncRef(fs *Filesystem) bool
+ TryIncRef() bool
// DecRef decrements the Dentry's reference count.
- DecRef(fs *Filesystem)
+ DecRef()
}
// IsDisowned returns true if d is disowned.
@@ -146,16 +146,20 @@ func (d *Dentry) isMounted() bool {
return atomic.LoadUint32(&d.mounts) != 0
}
-func (d *Dentry) incRef(fs *Filesystem) {
- d.impl.IncRef(fs)
+// IncRef increments d's reference count.
+func (d *Dentry) IncRef() {
+ d.impl.IncRef()
}
-func (d *Dentry) tryIncRef(fs *Filesystem) bool {
- return d.impl.TryIncRef(fs)
+// TryIncRef increments d's reference count and returns true. If d's reference
+// count is zero, TryIncRef may instead do nothing and return false.
+func (d *Dentry) TryIncRef() bool {
+ return d.impl.TryIncRef()
}
-func (d *Dentry) decRef(fs *Filesystem) {
- d.impl.DecRef(fs)
+// DecRef decrements d's reference count.
+func (d *Dentry) DecRef() {
+ d.impl.DecRef()
}
// These functions are exported so that filesystem implementations can use
@@ -420,6 +424,6 @@ func (vfs *VirtualFilesystem) forgetDisownedMountpoint(d *Dentry) {
vd.DecRef()
}
for _, mnt := range mountsToDecRef {
- mnt.decRef()
+ mnt.DecRef()
}
}
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 3a9665800..34007eb57 100644
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -47,15 +47,14 @@ type FileDescription struct {
impl FileDescriptionImpl
}
-// Init must be called before first use of fd. It takes references on mnt and
-// d.
+// Init must be called before first use of fd. It takes ownership of references
+// on mnt and d held by the caller.
func (fd *FileDescription) Init(impl FileDescriptionImpl, mnt *Mount, d *Dentry) {
fd.refs = 1
fd.vd = VirtualDentry{
mount: mnt,
dentry: d,
}
- fd.vd.IncRef()
fd.impl = impl
}
@@ -64,6 +63,18 @@ func (fd *FileDescription) Impl() FileDescriptionImpl {
return fd.impl
}
+// Mount returns the mount on which fd was opened. It does not take a reference
+// on the returned Mount.
+func (fd *FileDescription) Mount() *Mount {
+ return fd.vd.mount
+}
+
+// Dentry returns the dentry at which fd was opened. It does not take a
+// reference on the returned Dentry.
+func (fd *FileDescription) Dentry() *Dentry {
+ return fd.vd.dentry
+}
+
// VirtualDentry returns the location at which fd was opened. It does not take
// a reference on the returned VirtualDentry.
func (fd *FileDescription) VirtualDentry() VirtualDentry {
@@ -75,6 +86,22 @@ func (fd *FileDescription) IncRef() {
atomic.AddInt64(&fd.refs, 1)
}
+// TryIncRef increments fd's reference count and returns true. If fd's
+// reference count is already zero, TryIncRef does nothing and returns false.
+//
+// TryIncRef does not require that a reference is held on fd.
+func (fd *FileDescription) TryIncRef() bool {
+ for {
+ refs := atomic.LoadInt64(&fd.refs)
+ if refs <= 0 {
+ return false
+ }
+ if atomic.CompareAndSwapInt64(&fd.refs, refs, refs+1) {
+ return true
+ }
+ }
+}
+
// DecRef decrements fd's reference count.
func (fd *FileDescription) DecRef() {
if refs := atomic.AddInt64(&fd.refs, -1); refs == 0 {
diff --git a/pkg/sentry/vfs/file_description_impl_util_test.go b/pkg/sentry/vfs/file_description_impl_util_test.go
index 511b829fc..a5561dcbe 100644
--- a/pkg/sentry/vfs/file_description_impl_util_test.go
+++ b/pkg/sentry/vfs/file_description_impl_util_test.go
@@ -90,7 +90,7 @@ func TestGenCountFD(t *testing.T) {
vfsObj := New() // vfs.New()
vfsObj.MustRegisterFilesystemType("testfs", FDTestFilesystemType{})
- mntns, err := vfsObj.NewMountNamespace(ctx, creds, "", "testfs", &NewFilesystemOptions{})
+ mntns, err := vfsObj.NewMountNamespace(ctx, creds, "", "testfs", &GetFilesystemOptions{})
if err != nil {
t.Fatalf("failed to create testfs root mount: %v", err)
}
diff --git a/pkg/sentry/vfs/filesystem.go b/pkg/sentry/vfs/filesystem.go
index 7a074b718..76ff8cf51 100644
--- a/pkg/sentry/vfs/filesystem.go
+++ b/pkg/sentry/vfs/filesystem.go
@@ -33,29 +33,41 @@ type Filesystem struct {
// operations.
refs int64
+ // vfs is the VirtualFilesystem that uses this Filesystem. vfs is
+ // immutable.
+ vfs *VirtualFilesystem
+
// impl is the FilesystemImpl associated with this Filesystem. impl is
// immutable. This should be the last field in Dentry.
impl FilesystemImpl
}
// Init must be called before first use of fs.
-func (fs *Filesystem) Init(impl FilesystemImpl) {
+func (fs *Filesystem) Init(vfsObj *VirtualFilesystem, impl FilesystemImpl) {
fs.refs = 1
+ fs.vfs = vfsObj
fs.impl = impl
}
+// VirtualFilesystem returns the containing VirtualFilesystem.
+func (fs *Filesystem) VirtualFilesystem() *VirtualFilesystem {
+ return fs.vfs
+}
+
// Impl returns the FilesystemImpl associated with fs.
func (fs *Filesystem) Impl() FilesystemImpl {
return fs.impl
}
-func (fs *Filesystem) incRef() {
+// IncRef increments fs' reference count.
+func (fs *Filesystem) IncRef() {
if atomic.AddInt64(&fs.refs, 1) <= 1 {
- panic("Filesystem.incRef() called without holding a reference")
+ panic("Filesystem.IncRef() called without holding a reference")
}
}
-func (fs *Filesystem) decRef() {
+// DecRef decrements fs' reference count.
+func (fs *Filesystem) DecRef() {
if refs := atomic.AddInt64(&fs.refs, -1); refs == 0 {
fs.impl.Release()
} else if refs < 0 {
diff --git a/pkg/sentry/vfs/filesystem_type.go b/pkg/sentry/vfs/filesystem_type.go
index f401ad7f3..c335e206d 100644
--- a/pkg/sentry/vfs/filesystem_type.go
+++ b/pkg/sentry/vfs/filesystem_type.go
@@ -25,21 +25,21 @@ import (
//
// FilesystemType is analogous to Linux's struct file_system_type.
type FilesystemType interface {
- // NewFilesystem returns a Filesystem configured by the given options,
+ // GetFilesystem returns a Filesystem configured by the given options,
// along with its mount root. A reference is taken on the returned
// Filesystem and Dentry.
- NewFilesystem(ctx context.Context, creds *auth.Credentials, source string, opts NewFilesystemOptions) (*Filesystem, *Dentry, error)
+ GetFilesystem(ctx context.Context, vfsObj *VirtualFilesystem, creds *auth.Credentials, source string, opts GetFilesystemOptions) (*Filesystem, *Dentry, error)
}
-// NewFilesystemOptions contains options to FilesystemType.NewFilesystem.
-type NewFilesystemOptions struct {
+// GetFilesystemOptions contains options to FilesystemType.GetFilesystem.
+type GetFilesystemOptions struct {
// Data is the string passed as the 5th argument to mount(2), which is
// usually a comma-separated list of filesystem-specific mount options.
Data string
// InternalData holds opaque FilesystemType-specific data. There is
// intentionally no way for applications to specify InternalData; if it is
- // not nil, the call to NewFilesystem originates from within the sentry.
+ // not nil, the call to GetFilesystem originates from within the sentry.
InternalData interface{}
}
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index 198fb8067..1c3b2e987 100644
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -110,12 +110,12 @@ type MountNamespace struct {
// NewMountNamespace returns a new mount namespace with a root filesystem
// configured by the given arguments. A reference is taken on the returned
// MountNamespace.
-func (vfs *VirtualFilesystem) NewMountNamespace(ctx context.Context, creds *auth.Credentials, source, fsTypeName string, opts *NewFilesystemOptions) (*MountNamespace, error) {
+func (vfs *VirtualFilesystem) NewMountNamespace(ctx context.Context, creds *auth.Credentials, source, fsTypeName string, opts *GetFilesystemOptions) (*MountNamespace, error) {
fsType := vfs.getFilesystemType(fsTypeName)
if fsType == nil {
return nil, syserror.ENODEV
}
- fs, root, err := fsType.NewFilesystem(ctx, creds, source, *opts)
+ fs, root, err := fsType.GetFilesystem(ctx, vfs, creds, source, *opts)
if err != nil {
return nil, err
}
@@ -133,13 +133,13 @@ func (vfs *VirtualFilesystem) NewMountNamespace(ctx context.Context, creds *auth
return mntns, nil
}
-// NewMount creates and mounts a new Filesystem.
-func (vfs *VirtualFilesystem) NewMount(ctx context.Context, creds *auth.Credentials, source string, target *PathOperation, fsTypeName string, opts *NewFilesystemOptions) error {
+// NewMount creates and mounts a Filesystem configured by the given arguments.
+func (vfs *VirtualFilesystem) NewMount(ctx context.Context, creds *auth.Credentials, source string, target *PathOperation, fsTypeName string, opts *GetFilesystemOptions) error {
fsType := vfs.getFilesystemType(fsTypeName)
if fsType == nil {
return syserror.ENODEV
}
- fs, root, err := fsType.NewFilesystem(ctx, creds, source, *opts)
+ fs, root, err := fsType.GetFilesystem(ctx, vfs, creds, source, *opts)
if err != nil {
return err
}
@@ -147,8 +147,8 @@ func (vfs *VirtualFilesystem) NewMount(ctx context.Context, creds *auth.Credenti
// lock ordering.
vd, err := vfs.GetDentryAt(ctx, creds, target, &GetDentryOptions{})
if err != nil {
- root.decRef(fs)
- fs.decRef()
+ root.DecRef()
+ fs.DecRef()
return err
}
vfs.mountMu.Lock()
@@ -158,8 +158,8 @@ func (vfs *VirtualFilesystem) NewMount(ctx context.Context, creds *auth.Credenti
vd.dentry.mu.Unlock()
vfs.mountMu.Unlock()
vd.DecRef()
- root.decRef(fs)
- fs.decRef()
+ root.DecRef()
+ fs.DecRef()
return syserror.ENOENT
}
// vd might have been mounted over between vfs.GetDentryAt() and
@@ -179,7 +179,7 @@ func (vfs *VirtualFilesystem) NewMount(ctx context.Context, creds *auth.Credenti
break
}
// This can't fail since we're holding vfs.mountMu.
- nextmnt.root.incRef(nextmnt.fs)
+ nextmnt.root.IncRef()
vd.dentry.mu.Unlock()
vd.DecRef()
vd = VirtualDentry{
@@ -229,7 +229,7 @@ type umountRecursiveOptions struct {
// Mounts on which references must be dropped to vdsToDecRef and mountsToDecRef
// respectively, and returns updated slices. (This is necessary because
// filesystem locks possibly taken by DentryImpl.DecRef() may precede
-// vfs.mountMu in the lock order, and Mount.decRef() may lock vfs.mountMu.)
+// vfs.mountMu in the lock order, and Mount.DecRef() may lock vfs.mountMu.)
//
// umountRecursiveLocked is analogous to Linux's fs/namespace.c:umount_tree().
//
@@ -322,13 +322,15 @@ func (mnt *Mount) tryIncMountedRef() bool {
}
}
-func (mnt *Mount) incRef() {
+// IncRef increments mnt's reference count.
+func (mnt *Mount) IncRef() {
// In general, negative values for mnt.refs are valid because the MSB is
// the eager-unmount bit.
atomic.AddInt64(&mnt.refs, 1)
}
-func (mnt *Mount) decRef() {
+// DecRef decrements mnt's reference count.
+func (mnt *Mount) DecRef() {
refs := atomic.AddInt64(&mnt.refs, -1)
if refs&^math.MinInt64 == 0 { // mask out MSB
var vd VirtualDentry
@@ -339,8 +341,8 @@ func (mnt *Mount) decRef() {
mnt.vfs.mounts.seq.EndWrite()
mnt.vfs.mountMu.Unlock()
}
- mnt.root.decRef(mnt.fs)
- mnt.fs.decRef()
+ mnt.root.DecRef()
+ mnt.fs.DecRef()
if vd.Ok() {
vd.DecRef()
}
@@ -368,7 +370,7 @@ func (mntns *MountNamespace) DecRef(vfs *VirtualFilesystem) {
vd.DecRef()
}
for _, mnt := range mountsToDecRef {
- mnt.decRef()
+ mnt.DecRef()
}
} else if refs < 0 {
panic("MountNamespace.DecRef() called without holding a reference")
@@ -413,7 +415,7 @@ retryFirst:
// Raced with umount.
continue
}
- mnt.decRef()
+ mnt.DecRef()
mnt = next
d = next.root
}
@@ -447,15 +449,15 @@ retryFirst:
// Raced with umount.
goto retryFirst
}
- if !point.tryIncRef(parent.fs) {
+ if !point.TryIncRef() {
// Since Mount holds a reference on Mount.key.point, this can only
// happen due to a racing change to Mount.key.
- parent.decRef()
+ parent.DecRef()
goto retryFirst
}
if !vfs.mounts.seq.ReadOk(epoch) {
- point.decRef(parent.fs)
- parent.decRef()
+ point.DecRef()
+ parent.DecRef()
goto retryFirst
}
mnt = parent
@@ -480,19 +482,19 @@ retryFirst:
// Raced with umount.
goto retryNotFirst
}
- if !point.tryIncRef(parent.fs) {
+ if !point.TryIncRef() {
// Since Mount holds a reference on Mount.key.point, this can
// only happen due to a racing change to Mount.key.
- parent.decRef()
+ parent.DecRef()
goto retryNotFirst
}
if !vfs.mounts.seq.ReadOk(epoch) {
- point.decRef(parent.fs)
- parent.decRef()
+ point.DecRef()
+ parent.DecRef()
goto retryNotFirst
}
- d.decRef(mnt.fs)
- mnt.decRef()
+ d.DecRef()
+ mnt.DecRef()
mnt = parent
d = point
}
diff --git a/pkg/sentry/vfs/resolving_path.go b/pkg/sentry/vfs/resolving_path.go
index 61bce6426..621f5a6f8 100644
--- a/pkg/sentry/vfs/resolving_path.go
+++ b/pkg/sentry/vfs/resolving_path.go
@@ -149,20 +149,20 @@ func (vfs *VirtualFilesystem) putResolvingPath(rp *ResolvingPath) {
func (rp *ResolvingPath) decRefStartAndMount() {
if rp.flags&rpflagsHaveStartRef != 0 {
- rp.start.decRef(rp.mount.fs)
+ rp.start.DecRef()
}
if rp.flags&rpflagsHaveMountRef != 0 {
- rp.mount.decRef()
+ rp.mount.DecRef()
}
}
func (rp *ResolvingPath) releaseErrorState() {
if rp.nextStart != nil {
- rp.nextStart.decRef(rp.nextMount.fs)
+ rp.nextStart.DecRef()
rp.nextStart = nil
}
if rp.nextMount != nil {
- rp.nextMount.decRef()
+ rp.nextMount.DecRef()
rp.nextMount = nil
}
}
diff --git a/pkg/sentry/vfs/syscalls.go b/pkg/sentry/vfs/syscalls.go
index 49952b2cc..436151afa 100644
--- a/pkg/sentry/vfs/syscalls.go
+++ b/pkg/sentry/vfs/syscalls.go
@@ -63,7 +63,7 @@ func (vfs *VirtualFilesystem) GetDentryAt(ctx context.Context, creds *auth.Crede
mount: rp.mount,
dentry: d,
}
- rp.mount.incRef()
+ rp.mount.IncRef()
vfs.putResolvingPath(rp)
return vd, nil
}
diff --git a/pkg/sentry/vfs/testutil.go b/pkg/sentry/vfs/testutil.go
index 70b192ece..593144cb7 100644
--- a/pkg/sentry/vfs/testutil.go
+++ b/pkg/sentry/vfs/testutil.go
@@ -33,10 +33,10 @@ type FDTestFilesystem struct {
vfsfs Filesystem
}
-// NewFilesystem implements FilesystemType.NewFilesystem.
-func (fstype FDTestFilesystemType) NewFilesystem(ctx context.Context, creds *auth.Credentials, source string, opts NewFilesystemOptions) (*Filesystem, *Dentry, error) {
+// GetFilesystem implements FilesystemType.GetFilesystem.
+func (fstype FDTestFilesystemType) GetFilesystem(ctx context.Context, vfsObj *VirtualFilesystem, creds *auth.Credentials, source string, opts GetFilesystemOptions) (*Filesystem, *Dentry, error) {
var fs FDTestFilesystem
- fs.vfsfs.Init(&fs)
+ fs.vfsfs.Init(vfsObj, &fs)
return &fs.vfsfs, fs.NewDentry(), nil
}
@@ -126,14 +126,14 @@ func (fs *FDTestFilesystem) NewDentry() *Dentry {
}
// IncRef implements DentryImpl.IncRef.
-func (d *fdTestDentry) IncRef(vfsfs *Filesystem) {
+func (d *fdTestDentry) IncRef() {
}
// TryIncRef implements DentryImpl.TryIncRef.
-func (d *fdTestDentry) TryIncRef(vfsfs *Filesystem) bool {
+func (d *fdTestDentry) TryIncRef() bool {
return true
}
// DecRef implements DentryImpl.DecRef.
-func (d *fdTestDentry) DecRef(vfsfs *Filesystem) {
+func (d *fdTestDentry) DecRef() {
}
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 88e865d86..f0cd3ffe5 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -116,15 +116,15 @@ func (vd VirtualDentry) Ok() bool {
// IncRef increments the reference counts on the Mount and Dentry represented
// by vd.
func (vd VirtualDentry) IncRef() {
- vd.mount.incRef()
- vd.dentry.incRef(vd.mount.fs)
+ vd.mount.IncRef()
+ vd.dentry.IncRef()
}
// DecRef decrements the reference counts on the Mount and Dentry represented
// by vd.
func (vd VirtualDentry) DecRef() {
- vd.dentry.decRef(vd.mount.fs)
- vd.mount.decRef()
+ vd.dentry.DecRef()
+ vd.mount.DecRef()
}
// Mount returns the Mount associated with vd. It does not take a reference on
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-02 10:30:58 +0000