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-rw-r--r--pkg/sentry/fsimpl/kernfs/BUILD12
-rw-r--r--pkg/sentry/fsimpl/kernfs/fd_impl_util.go2
-rw-r--r--pkg/sentry/fsimpl/kernfs/filesystem.go159
-rw-r--r--pkg/sentry/fsimpl/kernfs/inode_impl_util.go2
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs.go33
5 files changed, 122 insertions, 86 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/BUILD b/pkg/sentry/fsimpl/kernfs/BUILD
index b3d6299d0..ef34cb28a 100644
--- a/pkg/sentry/fsimpl/kernfs/BUILD
+++ b/pkg/sentry/fsimpl/kernfs/BUILD
@@ -4,6 +4,17 @@ 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",
@@ -21,6 +32,7 @@ go_library(
"dynamic_bytes_file.go",
"fd_impl_util.go",
"filesystem.go",
+ "fstree.go",
"inode_impl_util.go",
"kernfs.go",
"slot_list.go",
diff --git a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
index bfa786c88..e8a4670b8 100644
--- a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
@@ -129,7 +129,7 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent
// Handle "..".
if fd.off == 1 {
- parentInode := vfsd.ParentOrSelf().Impl().(*Dentry).inode
+ parentInode := genericParentOrSelf(vfsd.Impl().(*Dentry)).inode
stat, err := parentInode.Stat(vfsFS, opts)
if err != nil {
return err
diff --git a/pkg/sentry/fsimpl/kernfs/filesystem.go b/pkg/sentry/fsimpl/kernfs/filesystem.go
index baf81b4db..01c23d192 100644
--- a/pkg/sentry/fsimpl/kernfs/filesystem.go
+++ b/pkg/sentry/fsimpl/kernfs/filesystem.go
@@ -56,25 +56,28 @@ afterSymlink:
return vfsd, nil
}
if name == ".." {
- nextVFSD, err := rp.ResolveParent(vfsd)
- if err != nil {
+ if isRoot, err := rp.CheckRoot(vfsd); err != nil {
+ return nil, err
+ } else if isRoot || d.parent == nil {
+ rp.Advance()
+ return vfsd, nil
+ }
+ if err := rp.CheckMount(&d.parent.vfsd); err != nil {
return nil, err
}
rp.Advance()
- return nextVFSD, nil
+ return &d.parent.vfsd, nil
}
if len(name) > linux.NAME_MAX {
return nil, syserror.ENAMETOOLONG
}
d.dirMu.Lock()
- nextVFSD, err := rp.ResolveChild(vfsd, name)
+ next, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), d, name, d.children[name])
+ d.dirMu.Unlock()
if err != nil {
- d.dirMu.Unlock()
return nil, err
}
- next, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), d, name, nextVFSD)
- d.dirMu.Unlock()
- if err != nil {
+ if err := rp.CheckMount(&next.vfsd); err != nil {
return nil, err
}
// Resolve any symlink at current path component.
@@ -108,17 +111,17 @@ afterSymlink:
// parent.dirMu must be locked. parent.isDir(). name is not "." or "..".
//
// Postconditions: Caller must call fs.processDeferredDecRefs*.
-func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *Dentry, name string, childVFSD *vfs.Dentry) (*Dentry, error) {
- if childVFSD != nil {
+func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *Dentry, name string, child *Dentry) (*Dentry, error) {
+ if child != nil {
// Cached dentry exists, revalidate.
- child := childVFSD.Impl().(*Dentry)
if !child.inode.Valid(ctx) {
- vfsObj.ForceDeleteDentry(childVFSD)
- fs.deferDecRef(childVFSD) // Reference from Lookup.
- childVFSD = nil
+ delete(parent.children, name)
+ vfsObj.InvalidateDentry(&child.vfsd)
+ fs.deferDecRef(&child.vfsd) // Reference from Lookup.
+ child = nil
}
}
- if childVFSD == nil {
+ if child == nil {
// Dentry isn't cached; it either doesn't exist or failed
// revalidation. Attempt to resolve it via Lookup.
//
@@ -126,15 +129,15 @@ func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
// *(kernfs.)Dentry, not *vfs.Dentry, since (kernfs.)Filesystem assumes
// that all dentries in the filesystem are (kernfs.)Dentry and performs
// vfs.DentryImpl casts accordingly.
- var err error
- childVFSD, err = parent.inode.Lookup(ctx, name)
+ childVFSD, err := parent.inode.Lookup(ctx, name)
if err != nil {
return nil, err
}
// Reference on childVFSD dropped by a corresponding Valid.
- parent.insertChildLocked(name, childVFSD)
+ child = childVFSD.Impl().(*Dentry)
+ parent.insertChildLocked(name, child)
}
- return childVFSD.Impl().(*Dentry), nil
+ return child, nil
}
// walkExistingLocked resolves rp to an existing file.
@@ -203,14 +206,11 @@ func checkCreateLocked(ctx context.Context, rp *vfs.ResolvingPath, parentVFSD *v
if len(pc) > linux.NAME_MAX {
return "", syserror.ENAMETOOLONG
}
- childVFSD, err := rp.ResolveChild(parentVFSD, pc)
- if err != nil {
- return "", err
- }
- if childVFSD != nil {
+ // FIXME(gvisor.dev/issue/1193): Data race due to not holding dirMu.
+ if _, ok := parentVFSD.Impl().(*Dentry).children[pc]; ok {
return "", syserror.EEXIST
}
- if parentVFSD.IsDisowned() {
+ if parentVFSD.IsDead() {
return "", syserror.ENOENT
}
return pc, nil
@@ -220,14 +220,14 @@ func checkCreateLocked(ctx context.Context, rp *vfs.ResolvingPath, parentVFSD *v
//
// Preconditions: Filesystem.mu must be locked for at least reading.
func checkDeleteLocked(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry) error {
- parentVFSD := vfsd.Parent()
- if parentVFSD == nil {
+ parent := vfsd.Impl().(*Dentry).parent
+ if parent == nil {
return syserror.EBUSY
}
- if parentVFSD.IsDisowned() {
+ if parent.vfsd.IsDead() {
return syserror.ENOENT
}
- if err := parentVFSD.Impl().(*Dentry).inode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+ if err := parent.inode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
return err
}
return nil
@@ -321,11 +321,11 @@ func (fs *Filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
return syserror.EPERM
}
- child, err := parentInode.NewLink(ctx, pc, d.inode)
+ childVFSD, err := parentInode.NewLink(ctx, pc, d.inode)
if err != nil {
return err
}
- parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
+ parentVFSD.Impl().(*Dentry).InsertChild(pc, childVFSD.Impl().(*Dentry))
return nil
}
@@ -349,11 +349,11 @@ func (fs *Filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
return err
}
defer rp.Mount().EndWrite()
- child, err := parentInode.NewDir(ctx, pc, opts)
+ childVFSD, err := parentInode.NewDir(ctx, pc, opts)
if err != nil {
return err
}
- parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
+ parentVFSD.Impl().(*Dentry).InsertChild(pc, childVFSD.Impl().(*Dentry))
return nil
}
@@ -377,11 +377,11 @@ func (fs *Filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
return err
}
defer rp.Mount().EndWrite()
- new, err := parentInode.NewNode(ctx, pc, opts)
+ newVFSD, err := parentInode.NewNode(ctx, pc, opts)
if err != nil {
return err
}
- parentVFSD.Impl().(*Dentry).InsertChild(pc, new)
+ parentVFSD.Impl().(*Dentry).InsertChild(pc, newVFSD.Impl().(*Dentry))
return nil
}
@@ -449,11 +449,8 @@ afterTrailingSymlink:
return nil, syserror.ENAMETOOLONG
}
// Determine whether or not we need to create a file.
- childVFSD, err := rp.ResolveChild(parentVFSD, pc)
- if err != nil {
- return nil, err
- }
- if childVFSD == nil {
+ childVFSD, err := fs.stepExistingLocked(ctx, rp, parentVFSD)
+ if err == syserror.ENOENT {
// Already checked for searchability above; now check for writability.
if err := parentInode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite); err != nil {
return nil, err
@@ -463,21 +460,24 @@ afterTrailingSymlink:
}
defer rp.Mount().EndWrite()
// Create and open the child.
- child, err := parentInode.NewFile(ctx, pc, opts)
+ childVFSD, err = parentInode.NewFile(ctx, pc, opts)
if err != nil {
return nil, err
}
+ child := childVFSD.Impl().(*Dentry)
parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
- return child.Impl().(*Dentry).inode.Open(rp, child, opts)
+ return child.inode.Open(rp, childVFSD, opts)
+ }
+ if err != nil {
+ return nil, err
}
// Open existing file or follow symlink.
if mustCreate {
return nil, syserror.EEXIST
}
- childDentry := childVFSD.Impl().(*Dentry)
- childInode := childDentry.inode
- if rp.ShouldFollowSymlink() && childDentry.isSymlink() {
- targetVD, targetPathname, err := childInode.Getlink(ctx)
+ child := childVFSD.Impl().(*Dentry)
+ if rp.ShouldFollowSymlink() && child.isSymlink() {
+ targetVD, targetPathname, err := child.inode.Getlink(ctx)
if err != nil {
return nil, err
}
@@ -496,10 +496,10 @@ afterTrailingSymlink:
// symlink target.
goto afterTrailingSymlink
}
- if err := childInode.CheckPermissions(ctx, rp.Credentials(), ats); err != nil {
+ if err := child.inode.CheckPermissions(ctx, rp.Credentials(), ats); err != nil {
return nil, err
}
- return childInode.Open(rp, childVFSD, opts)
+ return child.inode.Open(rp, &child.vfsd, opts)
}
// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt.
@@ -526,15 +526,16 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
noReplace := opts.Flags&linux.RENAME_NOREPLACE != 0
fs.mu.Lock()
- defer fs.mu.Lock()
+ defer fs.processDeferredDecRefsLocked()
+ defer fs.mu.Unlock()
// Resolve the destination directory first to verify that it's on this
// Mount.
dstDirVFSD, dstDirInode, err := fs.walkParentDirLocked(ctx, rp)
- fs.processDeferredDecRefsLocked()
if err != nil {
return err
}
+ dstDir := dstDirVFSD.Impl().(*Dentry)
mnt := rp.Mount()
if mnt != oldParentVD.Mount() {
return syserror.EXDEV
@@ -547,9 +548,8 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
srcDirVFSD := oldParentVD.Dentry()
srcDir := srcDirVFSD.Impl().(*Dentry)
srcDir.dirMu.Lock()
- src, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), srcDir, oldName, srcDirVFSD.Child(oldName))
+ src, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), srcDir, oldName, srcDir.children[oldName])
srcDir.dirMu.Unlock()
- fs.processDeferredDecRefsLocked()
if err != nil {
return err
}
@@ -561,7 +561,7 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
}
// Can we create the dst dentry?
- var dstVFSD *vfs.Dentry
+ var dst *Dentry
pc, err := checkCreateLocked(ctx, rp, dstDirVFSD, dstDirInode)
switch err {
case nil:
@@ -571,38 +571,51 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
// Won't overwrite existing node since RENAME_NOREPLACE was requested.
return syserror.EEXIST
}
- dstVFSD, err = rp.ResolveChild(dstDirVFSD, pc)
- if err != nil {
+ dst = dstDir.children[pc]
+ if dst == nil {
panic(fmt.Sprintf("Child %q for parent Dentry %+v disappeared inside atomic section?", pc, dstDirVFSD))
}
default:
return err
}
+ var dstVFSD *vfs.Dentry
+ if dst != nil {
+ dstVFSD = &dst.vfsd
+ }
mntns := vfs.MountNamespaceFromContext(ctx)
defer mntns.DecRef()
virtfs := rp.VirtualFilesystem()
- srcDirDentry := srcDirVFSD.Impl().(*Dentry)
- dstDirDentry := dstDirVFSD.Impl().(*Dentry)
-
// We can't deadlock here due to lock ordering because we're protected from
// concurrent renames by fs.mu held for writing.
- srcDirDentry.dirMu.Lock()
- defer srcDirDentry.dirMu.Unlock()
- dstDirDentry.dirMu.Lock()
- defer dstDirDentry.dirMu.Unlock()
+ srcDir.dirMu.Lock()
+ defer srcDir.dirMu.Unlock()
+ if srcDir != dstDir {
+ dstDir.dirMu.Lock()
+ defer dstDir.dirMu.Unlock()
+ }
if err := virtfs.PrepareRenameDentry(mntns, srcVFSD, dstVFSD); err != nil {
return err
}
- srcDirInode := srcDirDentry.inode
- replaced, err := srcDirInode.Rename(ctx, srcVFSD.Name(), pc, srcVFSD, dstDirVFSD)
+ replaced, err := srcDir.inode.Rename(ctx, src.name, pc, srcVFSD, dstDirVFSD)
if err != nil {
virtfs.AbortRenameDentry(srcVFSD, dstVFSD)
return err
}
- virtfs.CommitRenameReplaceDentry(srcVFSD, dstDirVFSD, pc, replaced)
+ delete(srcDir.children, src.name)
+ if srcDir != dstDir {
+ fs.deferDecRef(srcDirVFSD)
+ dstDir.IncRef()
+ }
+ src.parent = dstDir
+ src.name = pc
+ if dstDir.children == nil {
+ dstDir.children = make(map[string]*Dentry)
+ }
+ dstDir.children[pc] = src
+ virtfs.CommitRenameReplaceDentry(srcVFSD, replaced)
return nil
}
@@ -622,14 +635,15 @@ func (fs *Filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
if err := checkDeleteLocked(ctx, rp, vfsd); err != nil {
return err
}
- if !vfsd.Impl().(*Dentry).isDir() {
+ d := vfsd.Impl().(*Dentry)
+ if !d.isDir() {
return syserror.ENOTDIR
}
if inode.HasChildren() {
return syserror.ENOTEMPTY
}
virtfs := rp.VirtualFilesystem()
- parentDentry := vfsd.Parent().Impl().(*Dentry)
+ parentDentry := d.parent
parentDentry.dirMu.Lock()
defer parentDentry.dirMu.Unlock()
@@ -706,11 +720,11 @@ func (fs *Filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, targ
return err
}
defer rp.Mount().EndWrite()
- child, err := parentInode.NewSymlink(ctx, pc, target)
+ childVFSD, err := parentInode.NewSymlink(ctx, pc, target)
if err != nil {
return err
}
- parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
+ parentVFSD.Impl().(*Dentry).InsertChild(pc, childVFSD.Impl().(*Dentry))
return nil
}
@@ -730,11 +744,12 @@ func (fs *Filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
if err := checkDeleteLocked(ctx, rp, vfsd); err != nil {
return err
}
- if vfsd.Impl().(*Dentry).isDir() {
+ d := vfsd.Impl().(*Dentry)
+ if d.isDir() {
return syserror.EISDIR
}
virtfs := rp.VirtualFilesystem()
- parentDentry := vfsd.Parent().Impl().(*Dentry)
+ parentDentry := d.parent
parentDentry.dirMu.Lock()
defer parentDentry.dirMu.Unlock()
mntns := vfs.MountNamespaceFromContext(ctx)
@@ -818,5 +833,5 @@ func (fs *Filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath,
func (fs *Filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
fs.mu.RLock()
defer fs.mu.RUnlock()
- return vfs.GenericPrependPath(vfsroot, vd, b)
+ return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*Dentry), b)
}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index 65f09af5d..9f526359e 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -370,7 +370,7 @@ func (o *OrderedChildren) Populate(d *Dentry, children map[string]*Dentry) uint3
if err := o.Insert(name, child.VFSDentry()); err != nil {
panic(fmt.Sprintf("Collision when attempting to insert child %q (%+v) into %+v", name, child, d))
}
- d.InsertChild(name, child.VFSDentry())
+ d.InsertChild(name, child)
}
return links
}
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index ad76b9f64..f5041824f 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -168,17 +168,22 @@ const (
//
// Must be initialized by Init prior to first use.
type Dentry struct {
- refs.AtomicRefCount
+ vfsd vfs.Dentry
- vfsd vfs.Dentry
- inode Inode
+ refs.AtomicRefCount
// flags caches useful information about the dentry from the inode. See the
// dflags* consts above. Must be accessed by atomic ops.
flags uint32
- // dirMu protects vfsd.children for directory dentries.
- dirMu sync.Mutex
+ parent *Dentry
+ name string
+
+ // dirMu protects children and the names of child Dentries.
+ dirMu sync.Mutex
+ children map[string]*Dentry
+
+ inode Inode
}
// Init initializes this dentry.
@@ -222,8 +227,8 @@ func (d *Dentry) DecRef() {
func (d *Dentry) destroy() {
d.inode.DecRef() // IncRef from Init.
d.inode = nil
- if parent := d.vfsd.Parent(); parent != nil {
- parent.DecRef() // IncRef from Dentry.InsertChild.
+ if d.parent != nil {
+ d.parent.DecRef() // IncRef from Dentry.InsertChild.
}
}
@@ -233,7 +238,7 @@ func (d *Dentry) destroy() {
// updates the link count on d if required.
//
// Precondition: d must represent a directory inode.
-func (d *Dentry) InsertChild(name string, child *vfs.Dentry) {
+func (d *Dentry) InsertChild(name string, child *Dentry) {
d.dirMu.Lock()
d.insertChildLocked(name, child)
d.dirMu.Unlock()
@@ -243,13 +248,17 @@ func (d *Dentry) InsertChild(name string, child *vfs.Dentry) {
// preconditions.
//
// Precondition: d.dirMu must be locked.
-func (d *Dentry) insertChildLocked(name string, child *vfs.Dentry) {
+func (d *Dentry) insertChildLocked(name string, child *Dentry) {
if !d.isDir() {
panic(fmt.Sprintf("InsertChild called on non-directory Dentry: %+v.", d))
}
- vfsDentry := d.VFSDentry()
- vfsDentry.IncRef() // DecRef in child's Dentry.destroy.
- vfsDentry.InsertChild(child, name)
+ d.IncRef() // DecRef in child's Dentry.destroy.
+ child.parent = d
+ child.name = name
+ if d.children == nil {
+ d.children = make(map[string]*Dentry)
+ }
+ d.children[name] = child
}
// The Inode interface maps filesystem-level operations that operate on paths to
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-01 09:29:39 +0000