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-rw-r--r--pkg/sentry/fsimpl/overlay/copy_up.go2
-rw-r--r--pkg/sentry/fsimpl/overlay/filesystem.go126
-rw-r--r--pkg/sentry/fsimpl/overlay/overlay.go7
3 files changed, 70 insertions, 65 deletions
diff --git a/pkg/sentry/fsimpl/overlay/copy_up.go b/pkg/sentry/fsimpl/overlay/copy_up.go
index 4506642ca..469f3a33d 100644
--- a/pkg/sentry/fsimpl/overlay/copy_up.go
+++ b/pkg/sentry/fsimpl/overlay/copy_up.go
@@ -409,7 +409,7 @@ func (d *dentry) copyUpDescendantsLocked(ctx context.Context, ds **[]*dentry) er
if dirent.Name == "." || dirent.Name == ".." {
continue
}
- child, err := d.fs.getChildLocked(ctx, d, dirent.Name, ds)
+ child, _, err := d.fs.getChildLocked(ctx, d, dirent.Name, ds)
if err != nil {
return err
}
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index 04ca85f1a..30601e76d 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -22,6 +22,7 @@ import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/fspath"
+ "gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
"gvisor.dev/gvisor/pkg/sentry/vfs"
@@ -121,63 +122,63 @@ func (fs *filesystem) renameMuUnlockAndCheckDrop(ctx context.Context, ds **[]*de
// * fs.renameMu must be locked.
// * d.dirMu must be locked.
// * !rp.Done().
-func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, mayFollowSymlinks bool, ds **[]*dentry) (*dentry, error) {
+func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, mayFollowSymlinks bool, ds **[]*dentry) (*dentry, lookupLayer, error) {
if !d.isDir() {
- return nil, syserror.ENOTDIR
+ return nil, lookupLayerNone, syserror.ENOTDIR
}
if err := d.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
- return nil, err
+ return nil, lookupLayerNone, err
}
afterSymlink:
name := rp.Component()
if name == "." {
rp.Advance()
- return d, nil
+ return d, d.topLookupLayer(), nil
}
if name == ".." {
if isRoot, err := rp.CheckRoot(ctx, &d.vfsd); err != nil {
- return nil, err
+ return nil, lookupLayerNone, err
} else if isRoot || d.parent == nil {
rp.Advance()
- return d, nil
+ return d, d.topLookupLayer(), nil
}
if err := rp.CheckMount(ctx, &d.parent.vfsd); err != nil {
- return nil, err
+ return nil, lookupLayerNone, err
}
rp.Advance()
- return d.parent, nil
+ return d.parent, d.parent.topLookupLayer(), nil
}
- child, err := fs.getChildLocked(ctx, d, name, ds)
+ child, topLookupLayer, err := fs.getChildLocked(ctx, d, name, ds)
if err != nil {
- return nil, err
+ return nil, topLookupLayer, err
}
if err := rp.CheckMount(ctx, &child.vfsd); err != nil {
- return nil, err
+ return nil, lookupLayerNone, err
}
if child.isSymlink() && mayFollowSymlinks && rp.ShouldFollowSymlink() {
target, err := child.readlink(ctx)
if err != nil {
- return nil, err
+ return nil, lookupLayerNone, err
}
if err := rp.HandleSymlink(target); err != nil {
- return nil, err
+ return nil, topLookupLayer, err
}
goto afterSymlink // don't check the current directory again
}
rp.Advance()
- return child, nil
+ return child, topLookupLayer, nil
}
// Preconditions:
// * fs.renameMu must be locked.
// * d.dirMu must be locked.
-func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name string, ds **[]*dentry) (*dentry, error) {
+func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name string, ds **[]*dentry) (*dentry, lookupLayer, error) {
if child, ok := parent.children[name]; ok {
- return child, nil
+ return child, child.topLookupLayer(), nil
}
- child, err := fs.lookupLocked(ctx, parent, name)
+ child, topLookupLayer, err := fs.lookupLocked(ctx, parent, name)
if err != nil {
- return nil, err
+ return nil, topLookupLayer, err
}
if parent.children == nil {
parent.children = make(map[string]*dentry)
@@ -185,16 +186,16 @@ func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name s
parent.children[name] = child
// child's refcount is initially 0, so it may be dropped after traversal.
*ds = appendDentry(*ds, child)
- return child, nil
+ return child, topLookupLayer, nil
}
// Preconditions:
// * fs.renameMu must be locked.
// * parent.dirMu must be locked.
-func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name string) (*dentry, error) {
+func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name string) (*dentry, lookupLayer, error) {
childPath := fspath.Parse(name)
child := fs.newDentry()
- existsOnAnyLayer := false
+ topLookupLayer := lookupLayerNone
var lookupErr error
vfsObj := fs.vfsfs.VirtualFilesystem()
@@ -215,7 +216,7 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
defer childVD.DecRef(ctx)
mask := uint32(linux.STATX_TYPE)
- if !existsOnAnyLayer {
+ if topLookupLayer == lookupLayerNone {
// Mode, UID, GID, and (for non-directories) inode number come from
// the topmost layer on which the file exists.
mask |= linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO
@@ -238,10 +239,13 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
if isWhiteout(&stat) {
// This is a whiteout, so it "doesn't exist" on this layer, and
// layers below this one are ignored.
+ if isUpper {
+ topLookupLayer = lookupLayerUpperWhiteout
+ }
return false
}
isDir := stat.Mode&linux.S_IFMT == linux.S_IFDIR
- if existsOnAnyLayer && !isDir {
+ if topLookupLayer != lookupLayerNone && !isDir {
// Directories are not merged with non-directory files from lower
// layers; instead, layers including and below the first
// non-directory file are ignored. (This file must be a directory
@@ -258,8 +262,12 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
} else {
child.lowerVDs = append(child.lowerVDs, childVD)
}
- if !existsOnAnyLayer {
- existsOnAnyLayer = true
+ if topLookupLayer == lookupLayerNone {
+ if isUpper {
+ topLookupLayer = lookupLayerUpper
+ } else {
+ topLookupLayer = lookupLayerLower
+ }
child.mode = uint32(stat.Mode)
child.uid = stat.UID
child.gid = stat.GID
@@ -288,11 +296,11 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
if lookupErr != nil {
child.destroyLocked(ctx)
- return nil, lookupErr
+ return nil, topLookupLayer, lookupErr
}
- if !existsOnAnyLayer {
+ if !topLookupLayer.existsInOverlay() {
child.destroyLocked(ctx)
- return nil, syserror.ENOENT
+ return nil, topLookupLayer, syserror.ENOENT
}
// Device and inode numbers were copied from the topmost layer above;
@@ -306,7 +314,7 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
if err != nil {
ctx.Infof("overlay.filesystem.lookupLocked: failed to map lower layer device number (%d, %d) to an overlay-specific device number: %v", child.devMajor, child.devMinor, err)
child.destroyLocked(ctx)
- return nil, err
+ return nil, topLookupLayer, err
}
child.devMajor = linux.UNNAMED_MAJOR
child.devMinor = childDevMinor
@@ -315,7 +323,7 @@ func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name str
parent.IncRef()
child.parent = parent
child.name = name
- return child, nil
+ return child, topLookupLayer, nil
}
// lookupLayerLocked is similar to lookupLocked, but only returns information
@@ -414,7 +422,7 @@ func (ll lookupLayer) existsInOverlay() bool {
func (fs *filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) {
for !rp.Final() {
d.dirMu.Lock()
- next, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds)
+ next, _, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds)
d.dirMu.Unlock()
if err != nil {
return nil, err
@@ -434,7 +442,7 @@ func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath,
d := rp.Start().Impl().(*dentry)
for !rp.Done() {
d.dirMu.Lock()
- next, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds)
+ next, _, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds)
d.dirMu.Unlock()
if err != nil {
return nil, err
@@ -797,9 +805,9 @@ afterTrailingSymlink:
}
// Determine whether or not we need to create a file.
parent.dirMu.Lock()
- child, err := fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds)
+ child, topLookupLayer, err := fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds)
if err == syserror.ENOENT && mayCreate {
- fd, err := fs.createAndOpenLocked(ctx, rp, parent, &opts, &ds)
+ fd, err := fs.createAndOpenLocked(ctx, rp, parent, &opts, &ds, topLookupLayer == lookupLayerUpperWhiteout)
parent.dirMu.Unlock()
return fd, err
}
@@ -899,7 +907,7 @@ func (d *dentry) openCopiedUp(ctx context.Context, rp *vfs.ResolvingPath, opts *
// Preconditions:
// * parent.dirMu must be locked.
// * parent does not already contain a child named rp.Component().
-func (fs *filesystem) createAndOpenLocked(ctx context.Context, rp *vfs.ResolvingPath, parent *dentry, opts *vfs.OpenOptions, ds **[]*dentry) (*vfs.FileDescription, error) {
+func (fs *filesystem) createAndOpenLocked(ctx context.Context, rp *vfs.ResolvingPath, parent *dentry, opts *vfs.OpenOptions, ds **[]*dentry, haveUpperWhiteout bool) (*vfs.FileDescription, error) {
creds := rp.Credentials()
if err := parent.checkPermissions(creds, vfs.MayWrite); err != nil {
return nil, err
@@ -924,19 +932,12 @@ func (fs *filesystem) createAndOpenLocked(ctx context.Context, rp *vfs.Resolving
Start: parent.upperVD,
Path: fspath.Parse(childName),
}
- // We don't know if a whiteout exists on the upper layer; speculatively
- // unlink it.
- //
- // TODO(gvisor.dev/issue/1199): Modify OpenAt => stepLocked so that we do
- // know whether a whiteout exists.
- var haveUpperWhiteout bool
- switch err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err {
- case nil:
- haveUpperWhiteout = true
- case syserror.ENOENT:
- haveUpperWhiteout = false
- default:
- return nil, err
+ // Unlink the whiteout if it exists.
+ if haveUpperWhiteout {
+ if err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err != nil {
+ log.Warningf("overlay.filesystem.createAndOpenLocked: failed to unlink whiteout: %v", err)
+ return nil, err
+ }
}
// Create the file on the upper layer, and get an FD representing it.
upperFD, err := vfsObj.OpenAt(ctx, fs.creds, &pop, &vfs.OpenOptions{
@@ -967,7 +968,7 @@ func (fs *filesystem) createAndOpenLocked(ctx context.Context, rp *vfs.Resolving
}
// Re-lookup to get a dentry representing the new file, which is needed for
// the returned FD.
- child, err := fs.getChildLocked(ctx, parent, childName, ds)
+ child, _, err := fs.getChildLocked(ctx, parent, childName, ds)
if err != nil {
if cleanupErr := vfsObj.UnlinkAt(ctx, fs.creds, &pop); cleanupErr != nil {
panic(fmt.Sprintf("unrecoverable overlayfs inconsistency: failed to delete upper layer file after OpenAt(O_CREAT) dentry lookup failure: %v", cleanupErr))
@@ -1047,7 +1048,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
// directory, we need to check for write permission on it.
oldParent.dirMu.Lock()
defer oldParent.dirMu.Unlock()
- renamed, err := fs.getChildLocked(ctx, oldParent, oldName, &ds)
+ renamed, _, err := fs.getChildLocked(ctx, oldParent, oldName, &ds)
if err != nil {
return err
}
@@ -1079,20 +1080,17 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
if newParent.vfsd.IsDead() {
return syserror.ENOENT
}
- replacedLayer, err := fs.lookupLayerLocked(ctx, newParent, newName)
- if err != nil {
- return err
- }
var (
- replaced *dentry
- replacedVFSD *vfs.Dentry
- whiteouts map[string]bool
+ replaced *dentry
+ replacedVFSD *vfs.Dentry
+ replacedLayer lookupLayer
+ whiteouts map[string]bool
)
- if replacedLayer.existsInOverlay() {
- replaced, err = fs.getChildLocked(ctx, newParent, newName, &ds)
- if err != nil {
- return err
- }
+ replaced, replacedLayer, err = fs.getChildLocked(ctx, newParent, newName, &ds)
+ if err != nil && err != syserror.ENOENT {
+ return err
+ }
+ if replaced != nil {
replacedVFSD = &replaced.vfsd
if replaced.isDir() {
if !renamed.isDir() {
@@ -1296,7 +1294,7 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
// Unlike UnlinkAt, we need a dentry representing the child directory being
// removed in order to verify that it's empty.
- child, err := fs.getChildLocked(ctx, parent, name, &ds)
+ child, _, err := fs.getChildLocked(ctx, parent, name, &ds)
if err != nil {
return err
}
@@ -1548,7 +1546,7 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
if parentMode&linux.S_ISVTX != 0 {
// If the parent's sticky bit is set, we need a child dentry to get
// its owner.
- child, err = fs.getChildLocked(ctx, parent, name, &ds)
+ child, _, err = fs.getChildLocked(ctx, parent, name, &ds)
if err != nil {
return err
}
diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go
index f6c58f2e7..73130bc8d 100644
--- a/pkg/sentry/fsimpl/overlay/overlay.go
+++ b/pkg/sentry/fsimpl/overlay/overlay.go
@@ -696,6 +696,13 @@ func (d *dentry) topLayer() vfs.VirtualDentry {
return vd
}
+func (d *dentry) topLookupLayer() lookupLayer {
+ if d.upperVD.Ok() {
+ return lookupLayerUpper
+ }
+ return lookupLayerLower
+}
+
func (d *dentry) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes) error {
return vfs.GenericCheckPermissions(creds, ats, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid)))
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 16:40:33 +0000