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authorJamie Liu <jamieliu@google.com>2021-09-01 13:05:27 -0700
committergVisor bot <gvisor-bot@google.com>2021-09-01 13:09:00 -0700
commit5da4270a884e9f0c88d583da34f757783f314645 (patch)
tree3b08497846c28217e560e45811a8d767cdefd320
parent927ea16dd384f675a2ce1456be457a371109c488 (diff)
Propagate vfs.MkdirOptions.ForSyntheticMountpoint to overlay copy-up.
PiperOrigin-RevId: 394296687
-rw-r--r--pkg/sentry/fsimpl/overlay/copy_up.go9
-rw-r--r--pkg/sentry/fsimpl/overlay/filesystem.go28
2 files changed, 27 insertions, 10 deletions
diff --git a/pkg/sentry/fsimpl/overlay/copy_up.go b/pkg/sentry/fsimpl/overlay/copy_up.go
index 618092ef1..520487066 100644
--- a/pkg/sentry/fsimpl/overlay/copy_up.go
+++ b/pkg/sentry/fsimpl/overlay/copy_up.go
@@ -36,6 +36,10 @@ func (d *dentry) isCopiedUp() bool {
//
// Preconditions: filesystem.renameMu must be locked.
func (d *dentry) copyUpLocked(ctx context.Context) error {
+ return d.copyUpMaybeSyntheticMountpointLocked(ctx, false /* forSyntheticMountpoint */)
+}
+
+func (d *dentry) copyUpMaybeSyntheticMountpointLocked(ctx context.Context, forSyntheticMountpoint bool) error {
// Fast path.
if d.isCopiedUp() {
return nil
@@ -59,7 +63,7 @@ func (d *dentry) copyUpLocked(ctx context.Context) error {
// d is a filesystem root with no upper layer.
return linuxerr.EROFS
}
- if err := d.parent.copyUpLocked(ctx); err != nil {
+ if err := d.parent.copyUpMaybeSyntheticMountpointLocked(ctx, forSyntheticMountpoint); err != nil {
return err
}
@@ -168,7 +172,8 @@ func (d *dentry) copyUpLocked(ctx context.Context) error {
case linux.S_IFDIR:
if err := vfsObj.MkdirAt(ctx, d.fs.creds, &newpop, &vfs.MkdirOptions{
- Mode: linux.FileMode(d.mode &^ linux.S_IFMT),
+ Mode: linux.FileMode(d.mode &^ linux.S_IFMT),
+ ForSyntheticMountpoint: forSyntheticMountpoint,
}); err != nil {
return err
}
diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go
index c04c80590..3b3dcf836 100644
--- a/pkg/sentry/fsimpl/overlay/filesystem.go
+++ b/pkg/sentry/fsimpl/overlay/filesystem.go
@@ -462,13 +462,21 @@ func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath,
return d, nil
}
+type createType int
+
+const (
+ createNonDirectory createType = iota
+ createDirectory
+ createSyntheticMountpoint
+)
+
// doCreateAt checks that creating a file at rp is permitted, then invokes
// create to do so.
//
// Preconditions:
// * !rp.Done().
// * For the final path component in rp, !rp.ShouldFollowSymlink().
-func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, create func(parent *dentry, name string, haveUpperWhiteout bool) error) error {
+func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, ct createType, create func(parent *dentry, name string, haveUpperWhiteout bool) error) error {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
@@ -504,7 +512,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
return linuxerr.EEXIST
}
- if !dir && rp.MustBeDir() {
+ if ct == createNonDirectory && rp.MustBeDir() {
return linuxerr.ENOENT
}
@@ -518,7 +526,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
}
// Ensure that the parent directory is copied-up so that we can create the
// new file in the upper layer.
- if err := parent.copyUpLocked(ctx); err != nil {
+ if err := parent.copyUpMaybeSyntheticMountpointLocked(ctx, ct == createSyntheticMountpoint); err != nil {
return err
}
@@ -529,7 +537,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
parent.dirents = nil
ev := linux.IN_CREATE
- if dir {
+ if ct != createNonDirectory {
ev |= linux.IN_ISDIR
}
parent.watches.Notify(ctx, name, uint32(ev), 0 /* cookie */, vfs.InodeEvent, false /* unlinked */)
@@ -618,7 +626,7 @@ func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPa
// LinkAt implements vfs.FilesystemImpl.LinkAt.
func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error {
- return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
+ return fs.doCreateAt(ctx, rp, createNonDirectory, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
if rp.Mount() != vd.Mount() {
return linuxerr.EXDEV
}
@@ -671,7 +679,11 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
// MkdirAt implements vfs.FilesystemImpl.MkdirAt.
func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error {
- return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
+ ct := createDirectory
+ if opts.ForSyntheticMountpoint {
+ ct = createSyntheticMountpoint
+ }
+ return fs.doCreateAt(ctx, rp, ct, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
vfsObj := fs.vfsfs.VirtualFilesystem()
pop := vfs.PathOperation{
Root: parent.upperVD,
@@ -722,7 +734,7 @@ func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
// MknodAt implements vfs.FilesystemImpl.MknodAt.
func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error {
- return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
+ return fs.doCreateAt(ctx, rp, createNonDirectory, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
// Disallow attempts to create whiteouts.
if opts.Mode&linux.S_IFMT == linux.S_IFCHR && opts.DevMajor == 0 && opts.DevMinor == 0 {
return linuxerr.EPERM
@@ -1476,7 +1488,7 @@ func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linu
// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt.
func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error {
- return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
+ return fs.doCreateAt(ctx, rp, createNonDirectory, func(parent *dentry, childName string, haveUpperWhiteout bool) error {
vfsObj := fs.vfsfs.VirtualFilesystem()
pop := vfs.PathOperation{
Root: parent.upperVD,