4 files changed, 157 insertions, 2 deletions
diff --git a/pkg/abi/linux/fuse.go b/pkg/abi/linux/fuse.go
index f0bef1e8e..fcc957bfe 100644
--- a/pkg/abi/linux/fuse.go
+++ b/pkg/abi/linux/fuse.go
@@ -749,3 +749,70 @@ func (r *FUSEDirent) UnmarshalBytes(src []byte) {
 	name.UnmarshalBytes(src[:r.Meta.NameLen])
 	r.Name = string(name)
 }
+
+// FATTR_* consts are the attribute flags defined in include/uapi/linux/fuse.h.
+// These should be or-ed together for setattr to know what has been changed.
+const (
+	FATTR_MODE      = (1 << 0)
+	FATTR_UID       = (1 << 1)
+	FATTR_GID       = (1 << 2)
+	FATTR_SIZE      = (1 << 3)
+	FATTR_ATIME     = (1 << 4)
+	FATTR_MTIME     = (1 << 5)
+	FATTR_FH        = (1 << 6)
+	FATTR_ATIME_NOW = (1 << 7)
+	FATTR_MTIME_NOW = (1 << 8)
+	FATTR_LOCKOWNER = (1 << 9)
+	FATTR_CTIME     = (1 << 10)
+)
+
+// FUSESetAttrIn is the request sent by the kernel to the daemon,
+// to set the attribute(s) of a file.
+//
+// +marshal
+type FUSESetAttrIn struct {
+	// Valid indicates which attributes are modified by this request.
+	Valid uint32
+
+	_ uint32
+
+	// Fh is used to identify the file if FATTR_FH is set in Valid.
+	Fh uint64
+
+	// Size is the size that the request wants to change to.
+	Size uint64
+
+	// LockOwner is the owner of the lock that the request wants to change to.
+	LockOwner uint64
+
+	// Atime is the access time that the request wants to change to.
+	Atime uint64
+
+	// Mtime is the modification time that the request wants to change to.
+	Mtime uint64
+
+	// Ctime is the status change time that the request wants to change to.
+	Ctime uint64
+
+	// AtimeNsec is the nano second part of Atime.
+	AtimeNsec uint32
+
+	// MtimeNsec is the nano second part of Mtime.
+	MtimeNsec uint32
+
+	// CtimeNsec is the nano second part of Ctime.
+	CtimeNsec uint32
+
+	// Mode is the file mode that the request wants to change to.
+	Mode uint32
+
+	_ uint32
+
+	// UID is the user ID of the owner that the request wants to change to.
+	UID uint32
+
+	// GID is the group ID of the owner that the request wants to change to.
+	GID uint32
+
+	_ uint32
+}
diff --git a/pkg/sentry/fsimpl/fuse/file.go b/pkg/sentry/fsimpl/fuse/file.go
index 186ec2362..15c0e3f41 100644
--- a/pkg/sentry/fsimpl/fuse/file.go
+++ b/pkg/sentry/fsimpl/fuse/file.go
@@ -123,5 +123,5 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu
 // SetStat implements FileDescriptionImpl.SetStat.
 func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
 	creds := auth.CredentialsFromContext(ctx)
-	return fd.inode().SetStat(ctx, fd.inode().fs.VFSFilesystem(), creds, opts)
+	return fd.inode().setAttr(ctx, fd.inode().fs.VFSFilesystem(), creds, opts, true, fd.Fh)
 }
diff --git a/pkg/sentry/fsimpl/fuse/fusefs.go b/pkg/sentry/fsimpl/fuse/fusefs.go
index 821048d87..572245303 100644
--- a/pkg/sentry/fsimpl/fuse/fusefs.go
+++ b/pkg/sentry/fsimpl/fuse/fusefs.go
@@ -660,7 +660,7 @@ func (i *inode) getAttr(ctx context.Context, fs *vfs.Filesystem, opts vfs.StatOp
 	}
 
 	// Set the metadata of kernfs.InodeAttrs.
-	if err := i.SetStat(ctx, fs, creds, vfs.SetStatOptions{
+	if err := i.SetInodeStat(ctx, fs, creds, vfs.SetStatOptions{
 		Stat: statFromFUSEAttr(out.Attr, linux.STATX_ALL, i.fs.devMinor),
 	}); err != nil {
 		return linux.FUSEAttr{}, err
@@ -703,3 +703,84 @@ func (i *inode) StatFS(ctx context.Context, fs *vfs.Filesystem) (linux.Statfs, e
 	// TODO(gvisor.dev/issues/3413): Complete the implementation of statfs.
 	return vfs.GenericStatFS(linux.FUSE_SUPER_MAGIC), nil
 }
+
+// fattrMaskFromStats converts vfs.SetStatOptions.Stat.Mask to linux stats mask
+// aligned with the attribute mask defined in include/linux/fs.h.
+func fattrMaskFromStats(mask uint32) uint32 {
+	var fuseAttrMask uint32
+	maskMap := map[uint32]uint32{
+		linux.STATX_MODE:  linux.FATTR_MODE,
+		linux.STATX_UID:   linux.FATTR_UID,
+		linux.STATX_GID:   linux.FATTR_GID,
+		linux.STATX_SIZE:  linux.FATTR_SIZE,
+		linux.STATX_ATIME: linux.FATTR_ATIME,
+		linux.STATX_MTIME: linux.FATTR_MTIME,
+		linux.STATX_CTIME: linux.FATTR_CTIME,
+	}
+	for statxMask, fattrMask := range maskMap {
+		if mask&statxMask != 0 {
+			fuseAttrMask |= fattrMask
+		}
+	}
+	return fuseAttrMask
+}
+
+// SetStat implements kernfs.Inode.SetStat.
+func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
+	return i.setAttr(ctx, fs, creds, opts, false, 0)
+}
+
+func (i *inode) setAttr(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions, useFh bool, fh uint64) error {
+	conn := i.fs.conn
+	task := kernel.TaskFromContext(ctx)
+	if task == nil {
+		log.Warningf("couldn't get kernel task from context")
+		return syserror.EINVAL
+	}
+
+	// We should retain the original file type when assigning new mode.
+	fileType := uint16(i.Mode()) & linux.S_IFMT
+	fattrMask := fattrMaskFromStats(opts.Stat.Mask)
+	if useFh {
+		fattrMask |= linux.FATTR_FH
+	}
+	in := linux.FUSESetAttrIn{
+		Valid:     fattrMask,
+		Fh:        fh,
+		Size:      opts.Stat.Size,
+		Atime:     uint64(opts.Stat.Atime.Sec),
+		Mtime:     uint64(opts.Stat.Mtime.Sec),
+		Ctime:     uint64(opts.Stat.Ctime.Sec),
+		AtimeNsec: opts.Stat.Atime.Nsec,
+		MtimeNsec: opts.Stat.Mtime.Nsec,
+		CtimeNsec: opts.Stat.Ctime.Nsec,
+		Mode:      uint32(fileType | opts.Stat.Mode),
+		UID:       opts.Stat.UID,
+		GID:       opts.Stat.GID,
+	}
+	req, err := conn.NewRequest(creds, uint32(task.ThreadID()), i.NodeID, linux.FUSE_SETATTR, &in)
+	if err != nil {
+		return err
+	}
+
+	res, err := conn.Call(task, req)
+	if err != nil {
+		return err
+	}
+	if err := res.Error(); err != nil {
+		return err
+	}
+	out := linux.FUSEGetAttrOut{}
+	if err := res.UnmarshalPayload(&out); err != nil {
+		return err
+	}
+
+	// Set the metadata of kernfs.InodeAttrs.
+	if err := i.SetInodeStat(ctx, fs, creds, vfs.SetStatOptions{
+		Stat: statFromFUSEAttr(out.Attr, linux.STATX_ALL, i.fs.devMinor),
+	}); err != nil {
+		return err
+	}
+
+	return nil
+}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index ef63a1947..ea4f679c2 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -256,6 +256,13 @@ func (a *InodeAttrs) Stat(context.Context, *vfs.Filesystem, vfs.StatOptions) (li
 
 // SetStat implements Inode.SetStat.
 func (a *InodeAttrs) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
+	return a.SetInodeStat(ctx, fs, creds, opts)
+}
+
+// SetInodeStat sets the corresponding attributes from opts to InodeAttrs.
+// This function can be used by other kernfs-based filesystem implementation to
+// sets the unexported attributes into kernfs.InodeAttrs.
+func (a *InodeAttrs) SetInodeStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
 	if opts.Stat.Mask == 0 {
 		return nil
 	}