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Propagate vfs.MkdirOptions.ForSyntheticMountpoint to overlay copy-up. 

PiperOrigin-RevId: 394296687
This commit is contained in:
Jamie Liu 2021-09-01 13:05:27 -07:00 committed by gVisor bot
parent 927ea16dd3
commit 5da4270a88
2 changed files with 27 additions and 10 deletions
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9
pkg/sentry/fsimpl/overlay/copy_up.go
View File

@ -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
}

28
pkg/sentry/fsimpl/overlay/filesystem.go
View File

@ -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,