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-rw-r--r--pkg/sentry/fsimpl/kernfs/BUILD127
-rw-r--r--pkg/sentry/fsimpl/kernfs/dentry_refs.go118
-rw-r--r--pkg/sentry/fsimpl/kernfs/fstree.go46
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go232
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs_test.go346
-rw-r--r--pkg/sentry/fsimpl/kernfs/slot_list.go193
-rw-r--r--pkg/sentry/fsimpl/kernfs/static_directory_refs.go118
7 files changed, 707 insertions, 473 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/BUILD b/pkg/sentry/fsimpl/kernfs/BUILD
deleted file mode 100644
index 637dca70c..000000000
--- a/pkg/sentry/fsimpl/kernfs/BUILD
+++ /dev/null
@@ -1,127 +0,0 @@
-load("//tools:defs.bzl", "go_library", "go_test")
-load("//tools/go_generics:defs.bzl", "go_template_instance")
-
-licenses(["notice"])
-
-go_template_instance(
- name = "fstree",
- out = "fstree.go",
- package = "kernfs",
- prefix = "generic",
- template = "//pkg/sentry/vfs/genericfstree:generic_fstree",
- types = {
- "Dentry": "Dentry",
- },
-)
-
-go_template_instance(
- name = "slot_list",
- out = "slot_list.go",
- package = "kernfs",
- prefix = "slot",
- template = "//pkg/ilist:generic_list",
- types = {
- "Element": "*slot",
- "Linker": "*slot",
- },
-)
-
-go_template_instance(
- name = "dentry_refs",
- out = "dentry_refs.go",
- package = "kernfs",
- prefix = "Dentry",
- template = "//pkg/refs_vfs2:refs_template",
- types = {
- "T": "Dentry",
- },
-)
-
-go_template_instance(
- name = "static_directory_refs",
- out = "static_directory_refs.go",
- package = "kernfs",
- prefix = "StaticDirectory",
- template = "//pkg/refs_vfs2:refs_template",
- types = {
- "T": "StaticDirectory",
- },
-)
-
-go_template_instance(
- name = "dir_refs",
- out = "dir_refs.go",
- package = "kernfs_test",
- prefix = "dir",
- template = "//pkg/refs_vfs2:refs_template",
- types = {
- "T": "dir",
- },
-)
-
-go_template_instance(
- name = "readonly_dir_refs",
- out = "readonly_dir_refs.go",
- package = "kernfs_test",
- prefix = "readonlyDir",
- template = "//pkg/refs_vfs2:refs_template",
- types = {
- "T": "readonlyDir",
- },
-)
-
-go_library(
- name = "kernfs",
- srcs = [
- "dentry_refs.go",
- "dynamic_bytes_file.go",
- "fd_impl_util.go",
- "filesystem.go",
- "fstree.go",
- "inode_impl_util.go",
- "kernfs.go",
- "slot_list.go",
- "static_directory_refs.go",
- "symlink.go",
- ],
- visibility = ["//pkg/sentry:internal"],
- deps = [
- "//pkg/abi/linux",
- "//pkg/context",
- "//pkg/fspath",
- "//pkg/log",
- "//pkg/refs",
- "//pkg/sentry/fs/lock",
- "//pkg/sentry/kernel/auth",
- "//pkg/sentry/memmap",
- "//pkg/sentry/socket/unix/transport",
- "//pkg/sentry/vfs",
- "//pkg/sync",
- "//pkg/syserror",
- "//pkg/usermem",
- ],
-)
-
-go_test(
- name = "kernfs_test",
- size = "small",
- srcs = [
- "dir_refs.go",
- "kernfs_test.go",
- "readonly_dir_refs.go",
- ],
- deps = [
- ":kernfs",
- "//pkg/abi/linux",
- "//pkg/context",
- "//pkg/log",
- "//pkg/refs",
- "//pkg/sentry/contexttest",
- "//pkg/sentry/fsimpl/testutil",
- "//pkg/sentry/kernel/auth",
- "//pkg/sentry/vfs",
- "//pkg/syserror",
- "//pkg/usermem",
- "@com_github_google_go_cmp//cmp:go_default_library",
- ],
-)
diff --git a/pkg/sentry/fsimpl/kernfs/dentry_refs.go b/pkg/sentry/fsimpl/kernfs/dentry_refs.go
new file mode 100644
index 000000000..b7125caee
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/dentry_refs.go
@@ -0,0 +1,118 @@
+package kernfs
+
+import (
+ "runtime"
+ "sync/atomic"
+
+ "fmt"
+ "gvisor.dev/gvisor/pkg/log"
+ refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+)
+
+// ownerType is used to customize logging. Note that we use a pointer to T so
+// that we do not copy the entire object when passed as a format parameter.
+var DentryownerType *Dentry
+
+// Refs implements refs.RefCounter. It keeps a reference count using atomic
+// operations and calls the destructor when the count reaches zero.
+//
+// Note that the number of references is actually refCount + 1 so that a default
+// zero-value Refs object contains one reference.
+//
+// TODO(gvisor.dev/issue/1486): Store stack traces when leak check is enabled in
+// a map with 16-bit hashes, and store the hash in the top 16 bits of refCount.
+// This will allow us to add stack trace information to the leak messages
+// without growing the size of Refs.
+//
+// +stateify savable
+type DentryRefs struct {
+ // refCount is composed of two fields:
+ //
+ // [32-bit speculative references]:[32-bit real references]
+ //
+ // Speculative references are used for TryIncRef, to avoid a CompareAndSwap
+ // loop. See IncRef, DecRef and TryIncRef for details of how these fields are
+ // used.
+ refCount int64
+}
+
+func (r *DentryRefs) finalize() {
+ var note string
+ switch refs_vfs1.GetLeakMode() {
+ case refs_vfs1.NoLeakChecking:
+ return
+ case refs_vfs1.UninitializedLeakChecking:
+ note = "(Leak checker uninitialized): "
+ }
+ if n := r.ReadRefs(); n != 0 {
+ log.Warningf("%sRefs %p owned by %T garbage collected with ref count of %d (want 0)", note, r, DentryownerType, n)
+ }
+}
+
+// EnableLeakCheck checks for reference leaks when Refs gets garbage collected.
+func (r *DentryRefs) EnableLeakCheck() {
+ if refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking {
+ runtime.SetFinalizer(r, (*DentryRefs).finalize)
+ }
+}
+
+// ReadRefs returns the current number of references. The returned count is
+// inherently racy and is unsafe to use without external synchronization.
+func (r *DentryRefs) ReadRefs() int64 {
+
+ return atomic.LoadInt64(&r.refCount) + 1
+}
+
+// IncRef implements refs.RefCounter.IncRef.
+//
+//go:nosplit
+func (r *DentryRefs) IncRef() {
+ if v := atomic.AddInt64(&r.refCount, 1); v <= 0 {
+ panic(fmt.Sprintf("Incrementing non-positive ref count %p owned by %T", r, DentryownerType))
+ }
+}
+
+// TryIncRef implements refs.RefCounter.TryIncRef.
+//
+// To do this safely without a loop, a speculative reference is first acquired
+// on the object. This allows multiple concurrent TryIncRef calls to distinguish
+// other TryIncRef calls from genuine references held.
+//
+//go:nosplit
+func (r *DentryRefs) TryIncRef() bool {
+ const speculativeRef = 1 << 32
+ v := atomic.AddInt64(&r.refCount, speculativeRef)
+ if int32(v) < 0 {
+
+ atomic.AddInt64(&r.refCount, -speculativeRef)
+ return false
+ }
+
+ atomic.AddInt64(&r.refCount, -speculativeRef+1)
+ return true
+}
+
+// DecRef implements refs.RefCounter.DecRef.
+//
+// Note that speculative references are counted here. Since they were added
+// prior to real references reaching zero, they will successfully convert to
+// real references. In other words, we see speculative references only in the
+// following case:
+//
+// A: TryIncRef [speculative increase => sees non-negative references]
+// B: DecRef [real decrease]
+// A: TryIncRef [transform speculative to real]
+//
+//go:nosplit
+func (r *DentryRefs) DecRef(destroy func()) {
+ switch v := atomic.AddInt64(&r.refCount, -1); {
+ case v < -1:
+ panic(fmt.Sprintf("Decrementing non-positive ref count %p, owned by %T", r, DentryownerType))
+
+ case v == -1:
+
+ if destroy != nil {
+ destroy()
+ }
+ }
+}
diff --git a/pkg/sentry/fsimpl/kernfs/fstree.go b/pkg/sentry/fsimpl/kernfs/fstree.go
new file mode 100644
index 000000000..ce86d7919
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/fstree.go
@@ -0,0 +1,46 @@
+package kernfs
+
+import (
+ "gvisor.dev/gvisor/pkg/fspath"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
+// either d2's parent or an ancestor of d2's parent.
+func genericIsAncestorDentry(d, d2 *Dentry) bool {
+ for d2 != nil {
+ if d2.parent == d {
+ return true
+ }
+ if d2.parent == d2 {
+ return false
+ }
+ d2 = d2.parent
+ }
+ return false
+}
+
+// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
+func genericParentOrSelf(d *Dentry) *Dentry {
+ if d.parent != nil {
+ return d.parent
+ }
+ return d
+}
+
+// PrependPath is a generic implementation of FilesystemImpl.PrependPath().
+func genericPrependPath(vfsroot vfs.VirtualDentry, mnt *vfs.Mount, d *Dentry, b *fspath.Builder) error {
+ for {
+ if mnt == vfsroot.Mount() && &d.vfsd == vfsroot.Dentry() {
+ return vfs.PrependPathAtVFSRootError{}
+ }
+ if &d.vfsd == mnt.Root() {
+ return nil
+ }
+ if d.parent == nil {
+ return vfs.PrependPathAtNonMountRootError{}
+ }
+ b.PrependComponent(d.name)
+ d = d.parent
+ }
+}
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go b/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go
new file mode 100644
index 000000000..12aaf797f
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go
@@ -0,0 +1,232 @@
+// automatically generated by stateify.
+
+package kernfs
+
+import (
+ "gvisor.dev/gvisor/pkg/state"
+)
+
+func (x *DentryRefs) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.DentryRefs"
+}
+
+func (x *DentryRefs) StateFields() []string {
+ return []string{
+ "refCount",
+ }
+}
+
+func (x *DentryRefs) beforeSave() {}
+
+func (x *DentryRefs) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.refCount)
+}
+
+func (x *DentryRefs) afterLoad() {}
+
+func (x *DentryRefs) StateLoad(m state.Source) {
+ m.Load(0, &x.refCount)
+}
+
+func (x *DynamicBytesFile) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.DynamicBytesFile"
+}
+
+func (x *DynamicBytesFile) StateFields() []string {
+ return []string{
+ "InodeAttrs",
+ "InodeNoopRefCount",
+ "InodeNotDirectory",
+ "InodeNotSymlink",
+ "locks",
+ "data",
+ }
+}
+
+func (x *DynamicBytesFile) beforeSave() {}
+
+func (x *DynamicBytesFile) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.InodeAttrs)
+ m.Save(1, &x.InodeNoopRefCount)
+ m.Save(2, &x.InodeNotDirectory)
+ m.Save(3, &x.InodeNotSymlink)
+ m.Save(4, &x.locks)
+ m.Save(5, &x.data)
+}
+
+func (x *DynamicBytesFile) afterLoad() {}
+
+func (x *DynamicBytesFile) StateLoad(m state.Source) {
+ m.Load(0, &x.InodeAttrs)
+ m.Load(1, &x.InodeNoopRefCount)
+ m.Load(2, &x.InodeNotDirectory)
+ m.Load(3, &x.InodeNotSymlink)
+ m.Load(4, &x.locks)
+ m.Load(5, &x.data)
+}
+
+func (x *DynamicBytesFD) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.DynamicBytesFD"
+}
+
+func (x *DynamicBytesFD) StateFields() []string {
+ return []string{
+ "FileDescriptionDefaultImpl",
+ "DynamicBytesFileDescriptionImpl",
+ "LockFD",
+ "vfsfd",
+ "inode",
+ }
+}
+
+func (x *DynamicBytesFD) beforeSave() {}
+
+func (x *DynamicBytesFD) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.FileDescriptionDefaultImpl)
+ m.Save(1, &x.DynamicBytesFileDescriptionImpl)
+ m.Save(2, &x.LockFD)
+ m.Save(3, &x.vfsfd)
+ m.Save(4, &x.inode)
+}
+
+func (x *DynamicBytesFD) afterLoad() {}
+
+func (x *DynamicBytesFD) StateLoad(m state.Source) {
+ m.Load(0, &x.FileDescriptionDefaultImpl)
+ m.Load(1, &x.DynamicBytesFileDescriptionImpl)
+ m.Load(2, &x.LockFD)
+ m.Load(3, &x.vfsfd)
+ m.Load(4, &x.inode)
+}
+
+func (x *StaticDirectory) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.StaticDirectory"
+}
+
+func (x *StaticDirectory) StateFields() []string {
+ return []string{
+ "StaticDirectoryRefs",
+ "InodeNotSymlink",
+ "InodeDirectoryNoNewChildren",
+ "InodeAttrs",
+ "InodeNoDynamicLookup",
+ "OrderedChildren",
+ "locks",
+ "fdOpts",
+ }
+}
+
+func (x *StaticDirectory) beforeSave() {}
+
+func (x *StaticDirectory) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.StaticDirectoryRefs)
+ m.Save(1, &x.InodeNotSymlink)
+ m.Save(2, &x.InodeDirectoryNoNewChildren)
+ m.Save(3, &x.InodeAttrs)
+ m.Save(4, &x.InodeNoDynamicLookup)
+ m.Save(5, &x.OrderedChildren)
+ m.Save(6, &x.locks)
+ m.Save(7, &x.fdOpts)
+}
+
+func (x *StaticDirectory) afterLoad() {}
+
+func (x *StaticDirectory) StateLoad(m state.Source) {
+ m.Load(0, &x.StaticDirectoryRefs)
+ m.Load(1, &x.InodeNotSymlink)
+ m.Load(2, &x.InodeDirectoryNoNewChildren)
+ m.Load(3, &x.InodeAttrs)
+ m.Load(4, &x.InodeNoDynamicLookup)
+ m.Load(5, &x.OrderedChildren)
+ m.Load(6, &x.locks)
+ m.Load(7, &x.fdOpts)
+}
+
+func (x *slotList) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.slotList"
+}
+
+func (x *slotList) StateFields() []string {
+ return []string{
+ "head",
+ "tail",
+ }
+}
+
+func (x *slotList) beforeSave() {}
+
+func (x *slotList) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.head)
+ m.Save(1, &x.tail)
+}
+
+func (x *slotList) afterLoad() {}
+
+func (x *slotList) StateLoad(m state.Source) {
+ m.Load(0, &x.head)
+ m.Load(1, &x.tail)
+}
+
+func (x *slotEntry) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.slotEntry"
+}
+
+func (x *slotEntry) StateFields() []string {
+ return []string{
+ "next",
+ "prev",
+ }
+}
+
+func (x *slotEntry) beforeSave() {}
+
+func (x *slotEntry) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.next)
+ m.Save(1, &x.prev)
+}
+
+func (x *slotEntry) afterLoad() {}
+
+func (x *slotEntry) StateLoad(m state.Source) {
+ m.Load(0, &x.next)
+ m.Load(1, &x.prev)
+}
+
+func (x *StaticDirectoryRefs) StateTypeName() string {
+ return "pkg/sentry/fsimpl/kernfs.StaticDirectoryRefs"
+}
+
+func (x *StaticDirectoryRefs) StateFields() []string {
+ return []string{
+ "refCount",
+ }
+}
+
+func (x *StaticDirectoryRefs) beforeSave() {}
+
+func (x *StaticDirectoryRefs) StateSave(m state.Sink) {
+ x.beforeSave()
+ m.Save(0, &x.refCount)
+}
+
+func (x *StaticDirectoryRefs) afterLoad() {}
+
+func (x *StaticDirectoryRefs) StateLoad(m state.Source) {
+ m.Load(0, &x.refCount)
+}
+
+func init() {
+ state.Register((*DentryRefs)(nil))
+ state.Register((*DynamicBytesFile)(nil))
+ state.Register((*DynamicBytesFD)(nil))
+ state.Register((*StaticDirectory)(nil))
+ state.Register((*slotList)(nil))
+ state.Register((*slotEntry)(nil))
+ state.Register((*StaticDirectoryRefs)(nil))
+}
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_test.go b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
deleted file mode 100644
index e376d1736..000000000
--- a/pkg/sentry/fsimpl/kernfs/kernfs_test.go
+++ /dev/null
@@ -1,346 +0,0 @@
-// 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(ctx); 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, 0 /* devMajor */, 0 /* devMinor */, 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 {
- readonlyDirRefs
- attrs
- kernfs.InodeNotSymlink
- kernfs.InodeNoDynamicLookup
- kernfs.InodeDirectoryNoNewChildren
- kernfs.OrderedChildren
-
- locks vfs.FileLocks
-
- 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, 0 /* devMajor */, 0 /* devMinor */, fs.NextIno(), linux.ModeDirectory|mode)
- dir.OrderedChildren.Init(kernfs.OrderedChildrenOptions{})
- dir.EnableLeakCheck()
- 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, &d.locks, &opts, kernfs.GenericDirectoryFDOptions{
- SeekEnd: kernfs.SeekEndStaticEntries,
- })
- if err != nil {
- return nil, err
- }
- return fd.VFSFileDescription(), nil
-}
-
-func (d *readonlyDir) DecRef(context.Context) {
- d.readonlyDirRefs.DecRef(d.Destroy)
-}
-
-type dir struct {
- dirRefs
- attrs
- kernfs.InodeNotSymlink
- kernfs.InodeNoDynamicLookup
- kernfs.OrderedChildren
-
- locks vfs.FileLocks
-
- fs *filesystem
- dentry kernfs.Dentry
-}
-
-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, 0 /* devMajor */, 0 /* devMinor */, fs.NextIno(), linux.ModeDirectory|mode)
- dir.OrderedChildren.Init(kernfs.OrderedChildrenOptions{Writable: true})
- dir.EnableLeakCheck()
- 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, &d.locks, &opts, kernfs.GenericDirectoryFDOptions{
- SeekEnd: kernfs.SeekEndStaticEntries,
- })
- if err != nil {
- return nil, err
- }
- return fd.VFSFileDescription(), nil
-}
-
-func (d *dir) DecRef(context.Context) {
- d.dirRefs.DecRef(d.Destroy)
-}
-
-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(ctx)
- 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(ctx)
- 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.VFSFilesystem().Init(vfsObj, &fst, fs)
- 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(sys.Ctx)
-}
-
-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(sys.Ctx)
-}
-
-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(sys.Ctx)
-
- 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(sys.Ctx)
-
- 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(sys.Ctx)
-}
-
-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(sys.Ctx)
-
- // 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,
- })
-}
diff --git a/pkg/sentry/fsimpl/kernfs/slot_list.go b/pkg/sentry/fsimpl/kernfs/slot_list.go
new file mode 100644
index 000000000..c6cd74660
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/slot_list.go
@@ -0,0 +1,193 @@
+package kernfs
+
+// ElementMapper provides an identity mapping by default.
+//
+// This can be replaced to provide a struct that maps elements to linker
+// objects, if they are not the same. An ElementMapper is not typically
+// required if: Linker is left as is, Element is left as is, or Linker and
+// Element are the same type.
+type slotElementMapper struct{}
+
+// linkerFor maps an Element to a Linker.
+//
+// This default implementation should be inlined.
+//
+//go:nosplit
+func (slotElementMapper) linkerFor(elem *slot) *slot { return elem }
+
+// List is an intrusive list. Entries can be added to or removed from the list
+// in O(1) time and with no additional memory allocations.
+//
+// The zero value for List is an empty list ready to use.
+//
+// To iterate over a list (where l is a List):
+// for e := l.Front(); e != nil; e = e.Next() {
+// // do something with e.
+// }
+//
+// +stateify savable
+type slotList struct {
+ head *slot
+ tail *slot
+}
+
+// Reset resets list l to the empty state.
+func (l *slotList) Reset() {
+ l.head = nil
+ l.tail = nil
+}
+
+// Empty returns true iff the list is empty.
+func (l *slotList) Empty() bool {
+ return l.head == nil
+}
+
+// Front returns the first element of list l or nil.
+func (l *slotList) Front() *slot {
+ return l.head
+}
+
+// Back returns the last element of list l or nil.
+func (l *slotList) Back() *slot {
+ return l.tail
+}
+
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+func (l *slotList) Len() (count int) {
+ for e := l.Front(); e != nil; e = (slotElementMapper{}.linkerFor(e)).Next() {
+ count++
+ }
+ return count
+}
+
+// PushFront inserts the element e at the front of list l.
+func (l *slotList) PushFront(e *slot) {
+ linker := slotElementMapper{}.linkerFor(e)
+ linker.SetNext(l.head)
+ linker.SetPrev(nil)
+ if l.head != nil {
+ slotElementMapper{}.linkerFor(l.head).SetPrev(e)
+ } else {
+ l.tail = e
+ }
+
+ l.head = e
+}
+
+// PushBack inserts the element e at the back of list l.
+func (l *slotList) PushBack(e *slot) {
+ linker := slotElementMapper{}.linkerFor(e)
+ linker.SetNext(nil)
+ linker.SetPrev(l.tail)
+ if l.tail != nil {
+ slotElementMapper{}.linkerFor(l.tail).SetNext(e)
+ } else {
+ l.head = e
+ }
+
+ l.tail = e
+}
+
+// PushBackList inserts list m at the end of list l, emptying m.
+func (l *slotList) PushBackList(m *slotList) {
+ if l.head == nil {
+ l.head = m.head
+ l.tail = m.tail
+ } else if m.head != nil {
+ slotElementMapper{}.linkerFor(l.tail).SetNext(m.head)
+ slotElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
+
+ l.tail = m.tail
+ }
+ m.head = nil
+ m.tail = nil
+}
+
+// InsertAfter inserts e after b.
+func (l *slotList) InsertAfter(b, e *slot) {
+ bLinker := slotElementMapper{}.linkerFor(b)
+ eLinker := slotElementMapper{}.linkerFor(e)
+
+ a := bLinker.Next()
+
+ eLinker.SetNext(a)
+ eLinker.SetPrev(b)
+ bLinker.SetNext(e)
+
+ if a != nil {
+ slotElementMapper{}.linkerFor(a).SetPrev(e)
+ } else {
+ l.tail = e
+ }
+}
+
+// InsertBefore inserts e before a.
+func (l *slotList) InsertBefore(a, e *slot) {
+ aLinker := slotElementMapper{}.linkerFor(a)
+ eLinker := slotElementMapper{}.linkerFor(e)
+
+ b := aLinker.Prev()
+ eLinker.SetNext(a)
+ eLinker.SetPrev(b)
+ aLinker.SetPrev(e)
+
+ if b != nil {
+ slotElementMapper{}.linkerFor(b).SetNext(e)
+ } else {
+ l.head = e
+ }
+}
+
+// Remove removes e from l.
+func (l *slotList) Remove(e *slot) {
+ linker := slotElementMapper{}.linkerFor(e)
+ prev := linker.Prev()
+ next := linker.Next()
+
+ if prev != nil {
+ slotElementMapper{}.linkerFor(prev).SetNext(next)
+ } else if l.head == e {
+ l.head = next
+ }
+
+ if next != nil {
+ slotElementMapper{}.linkerFor(next).SetPrev(prev)
+ } else if l.tail == e {
+ l.tail = prev
+ }
+
+ linker.SetNext(nil)
+ linker.SetPrev(nil)
+}
+
+// Entry is a default implementation of Linker. Users can add anonymous fields
+// of this type to their structs to make them automatically implement the
+// methods needed by List.
+//
+// +stateify savable
+type slotEntry struct {
+ next *slot
+ prev *slot
+}
+
+// Next returns the entry that follows e in the list.
+func (e *slotEntry) Next() *slot {
+ return e.next
+}
+
+// Prev returns the entry that precedes e in the list.
+func (e *slotEntry) Prev() *slot {
+ return e.prev
+}
+
+// SetNext assigns 'entry' as the entry that follows e in the list.
+func (e *slotEntry) SetNext(elem *slot) {
+ e.next = elem
+}
+
+// SetPrev assigns 'entry' as the entry that precedes e in the list.
+func (e *slotEntry) SetPrev(elem *slot) {
+ e.prev = elem
+}
diff --git a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
new file mode 100644
index 000000000..0ff013c97
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
@@ -0,0 +1,118 @@
+package kernfs
+
+import (
+ "runtime"
+ "sync/atomic"
+
+ "fmt"
+ "gvisor.dev/gvisor/pkg/log"
+ refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+)
+
+// ownerType is used to customize logging. Note that we use a pointer to T so
+// that we do not copy the entire object when passed as a format parameter.
+var StaticDirectoryownerType *StaticDirectory
+
+// Refs implements refs.RefCounter. It keeps a reference count using atomic
+// operations and calls the destructor when the count reaches zero.
+//
+// Note that the number of references is actually refCount + 1 so that a default
+// zero-value Refs object contains one reference.
+//
+// TODO(gvisor.dev/issue/1486): Store stack traces when leak check is enabled in
+// a map with 16-bit hashes, and store the hash in the top 16 bits of refCount.
+// This will allow us to add stack trace information to the leak messages
+// without growing the size of Refs.
+//
+// +stateify savable
+type StaticDirectoryRefs struct {
+ // refCount is composed of two fields:
+ //
+ // [32-bit speculative references]:[32-bit real references]
+ //
+ // Speculative references are used for TryIncRef, to avoid a CompareAndSwap
+ // loop. See IncRef, DecRef and TryIncRef for details of how these fields are
+ // used.
+ refCount int64
+}
+
+func (r *StaticDirectoryRefs) finalize() {
+ var note string
+ switch refs_vfs1.GetLeakMode() {
+ case refs_vfs1.NoLeakChecking:
+ return
+ case refs_vfs1.UninitializedLeakChecking:
+ note = "(Leak checker uninitialized): "
+ }
+ if n := r.ReadRefs(); n != 0 {
+ log.Warningf("%sRefs %p owned by %T garbage collected with ref count of %d (want 0)", note, r, StaticDirectoryownerType, n)
+ }
+}
+
+// EnableLeakCheck checks for reference leaks when Refs gets garbage collected.
+func (r *StaticDirectoryRefs) EnableLeakCheck() {
+ if refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking {
+ runtime.SetFinalizer(r, (*StaticDirectoryRefs).finalize)
+ }
+}
+
+// ReadRefs returns the current number of references. The returned count is
+// inherently racy and is unsafe to use without external synchronization.
+func (r *StaticDirectoryRefs) ReadRefs() int64 {
+
+ return atomic.LoadInt64(&r.refCount) + 1
+}
+
+// IncRef implements refs.RefCounter.IncRef.
+//
+//go:nosplit
+func (r *StaticDirectoryRefs) IncRef() {
+ if v := atomic.AddInt64(&r.refCount, 1); v <= 0 {
+ panic(fmt.Sprintf("Incrementing non-positive ref count %p owned by %T", r, StaticDirectoryownerType))
+ }
+}
+
+// TryIncRef implements refs.RefCounter.TryIncRef.
+//
+// To do this safely without a loop, a speculative reference is first acquired
+// on the object. This allows multiple concurrent TryIncRef calls to distinguish
+// other TryIncRef calls from genuine references held.
+//
+//go:nosplit
+func (r *StaticDirectoryRefs) TryIncRef() bool {
+ const speculativeRef = 1 << 32
+ v := atomic.AddInt64(&r.refCount, speculativeRef)
+ if int32(v) < 0 {
+
+ atomic.AddInt64(&r.refCount, -speculativeRef)
+ return false
+ }
+
+ atomic.AddInt64(&r.refCount, -speculativeRef+1)
+ return true
+}
+
+// DecRef implements refs.RefCounter.DecRef.
+//
+// Note that speculative references are counted here. Since they were added
+// prior to real references reaching zero, they will successfully convert to
+// real references. In other words, we see speculative references only in the
+// following case:
+//
+// A: TryIncRef [speculative increase => sees non-negative references]
+// B: DecRef [real decrease]
+// A: TryIncRef [transform speculative to real]
+//
+//go:nosplit
+func (r *StaticDirectoryRefs) DecRef(destroy func()) {
+ switch v := atomic.AddInt64(&r.refCount, -1); {
+ case v < -1:
+ panic(fmt.Sprintf("Decrementing non-positive ref count %p, owned by %T", r, StaticDirectoryownerType))
+
+ case v == -1:
+
+ if destroy != nil {
+ destroy()
+ }
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 13:00:42 +0000