path: root/android-mainline/ANDROID-overlayfs-override_creds-off-option-bypass-creator_cred.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: David Anderson <dvander@google.com>
Date: Mon, 15 Nov 2021 22:03:30 -0800
Subject: ANDROID: overlayfs: override_creds=off option bypass creator_cred

By default, all access to the upper, lower and work directories is the
recorded mounter's MAC and DAC credentials.  The incoming accesses are
checked against the caller's credentials.

If the principles of least privilege are applied, the mounter's
credentials might not overlap the credentials of the caller's when
accessing the overlayfs filesystem.  For example, a file that a lower
DAC privileged caller can execute, is MAC denied to the generally
higher DAC privileged mounter, to prevent an attack vector.

We add the option to turn off override_creds in the mount options; all
subsequent operations after mount on the filesystem will be only the
caller's credentials.  The module boolean parameter and mount option
override_creds is also added as a presence check for this "feature",
existence of /sys/module/overlay/parameters/override_creds.

It was not always this way.  Circa 4.6 there was no recorded mounter's
credentials, instead privileged access to upper or work directories
were temporarily increased to perform the operations.  The MAC
(selinux) policies were caller's in all cases.  override_creds=off
partially returns us to this older access model minus the insecure
temporary credential increases.  This is to permit use in a system
with non-overlapping security models for each executable including
the agent that mounts the overlayfs filesystem.  In Android
this is the case since init, which performs the mount operations,
has a minimal MAC set of privileges to reduce any attack surface,
and services that use the content have a different set of MAC
privileges (eg: read, for vendor labelled configuration, execute for
vendor libraries and modules).  The caveats are not a problem in
the Android usage model, however they should be fixed for
completeness and for general use in time.

Bug: 297913716
Link: https://lore.kernel.org/lkml/20211117015806.2192263-4-dvander@google.com
Change-Id: If17ba2d7de0b339cf4a79f63009322080f1d8645
Signed-off-by: David Anderson <dvander@google.com>
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Test: adb-remount-test.sh
---
 Documentation/filesystems/overlayfs.rst | 24 ++++++++++++++++++++++
 fs/overlayfs/copy_up.c                  |  2 +-
 fs/overlayfs/dir.c                      | 17 +++++++++-------
 fs/overlayfs/file.c                     | 27 +++++++++++++------------
 fs/overlayfs/inode.c                    | 20 +++++++++---------
 fs/overlayfs/namei.c                    |  8 ++++----
 fs/overlayfs/overlayfs.h                |  1 +
 fs/overlayfs/ovl_entry.h                |  1 +
 fs/overlayfs/params.c                   | 10 +++++++++
 fs/overlayfs/readdir.c                  |  8 ++++----
 fs/overlayfs/util.c                     | 13 ++++++++++--
 11 files changed, 90 insertions(+), 41 deletions(-)

diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -323,6 +323,30 @@ and
 The resulting access permissions should be the same.  The difference is in
 the time of copy (on-demand vs. up-front).
 
+### Non overlapping credentials
+
+As noted above, all access to the upper, lower and work directories is the
+recorded mounter's MAC and DAC credentials.  The incoming accesses are
+checked against the caller's credentials.
+
+In the case where caller MAC or DAC credentials do not overlap the mounter, a
+use case available in older versions of the driver, the override_creds mount
+flag can be turned off.  For when the use pattern has caller with legitimate
+credentials where the mounter does not.  For example init may have been the
+mounter, but the caller would have execute or read MAC permissions where
+init would not.  override_creds off means all access, incoming, upper, lower
+or working, will be tested against the caller.
+
+Several unintended side effects will occur though.  The caller without certain
+key capabilities or lower privilege will not always be able to delete files or
+directories, create nodes, or search some restricted directories.  The ability
+to search and read a directory entry is spotty as a result of the cache
+mechanism not re-testing the credentials because of the assumption, a
+privileged caller can fill cache, then a lower privilege can read the directory
+cache.  The uneven security model where cache, upperdir and workdir are opened
+at privilege, but accessed without creating a form of privilege escalation,
+should only be used with strict understanding of the side effects and of the
+security policies.
 
 Multiple lower layers
 ---------------------
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -1195,7 +1195,7 @@ static int ovl_copy_up_flags(struct dentry *dentry, int flags)
 		dput(parent);
 		dput(next);
 	}
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 
 	return err;
 }
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -555,7 +555,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 			      struct ovl_cattr *attr, bool origin)
 {
 	int err;
-	const struct cred *old_cred;
+	const struct cred *old_cred, *hold_cred = NULL;
 	struct cred *override_cred;
 	struct dentry *parent = dentry->d_parent;
 
@@ -592,13 +592,14 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 		override_cred->fsuid = inode->i_uid;
 		override_cred->fsgid = inode->i_gid;
 		err = security_dentry_create_files_as(dentry,
-				attr->mode, &dentry->d_name, old_cred,
+				attr->mode, &dentry->d_name,
+				old_cred ? old_cred : current_cred(),
 				override_cred);
 		if (err) {
 			put_cred(override_cred);
 			goto out_revert_creds;
 		}
-		put_cred(override_creds(override_cred));
+		hold_cred = override_creds(override_cred);
 		put_cred(override_cred);
 	}
 
@@ -608,7 +609,9 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 		err = ovl_create_over_whiteout(dentry, inode, attr);
 
 out_revert_creds:
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred ?: hold_cred);
+	if (old_cred && hold_cred)
+		put_cred(hold_cred);
 	return err;
 }
 
@@ -689,7 +692,7 @@ static int ovl_set_link_redirect(struct dentry *dentry)
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	err = ovl_set_redirect(dentry, false);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 
 	return err;
 }
@@ -899,7 +902,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 		err = ovl_remove_upper(dentry, is_dir, &list);
 	else
 		err = ovl_remove_and_whiteout(dentry, &list);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	if (!err) {
 		if (is_dir)
 			clear_nlink(dentry->d_inode);
@@ -1275,7 +1278,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 out_unlock:
 	unlock_rename(new_upperdir, old_upperdir);
 out_revert_creds:
-	revert_creds(old_cred);
+	ovl_revert_creds(old->d_sb, old_cred);
 	if (update_nlink)
 		ovl_nlink_end(new);
 	else
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -62,13 +62,14 @@ static struct file *ovl_open_realfile(const struct file *file,
 	if (err) {
 		realfile = ERR_PTR(err);
 	} else {
-		if (!inode_owner_or_capable(real_idmap, realinode))
+		if (old_cred && !inode_owner_or_capable(real_idmap,
+							realinode))
 			flags &= ~O_NOATIME;
 
 		realfile = backing_file_open(&file->f_path, flags, realpath,
 					     current_cred());
 	}
-	revert_creds(old_cred);
+	ovl_revert_creds(inode->i_sb, old_cred);
 
 	pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
 		 file, file, ovl_whatisit(inode, realinode), file->f_flags,
@@ -230,7 +231,7 @@ static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
 
 	old_cred = ovl_override_creds(inode->i_sb);
 	ret = vfs_llseek(real.file, offset, whence);
-	revert_creds(old_cred);
+	ovl_revert_creds(inode->i_sb, old_cred);
 
 	file->f_pos = real.file->f_pos;
 	ovl_inode_unlock(inode);
@@ -387,7 +388,7 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 			ovl_aio_cleanup_handler(aio_req);
 	}
 out:
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 	ovl_file_accessed(file);
 out_fdput:
 	fdput(real);
@@ -465,7 +466,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 			ovl_aio_cleanup_handler(aio_req);
 	}
 out:
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 out_fdput:
 	fdput(real);
 
@@ -489,7 +490,7 @@ static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,
 
 	old_cred = ovl_override_creds(file_inode(in)->i_sb);
 	ret = vfs_splice_read(real.file, ppos, pipe, len, flags);
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(in)->i_sb, old_cred);
 	ovl_file_accessed(in);
 
 	fdput(real);
@@ -531,7 +532,7 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
 	file_end_write(real.file);
 	/* Update size */
 	ovl_file_modified(out);
-	revert_creds(old_cred);
+	ovl_revert_creds(inode->i_sb, old_cred);
 	fdput(real);
 
 out_unlock:
@@ -558,7 +559,7 @@ static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 	if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
 		old_cred = ovl_override_creds(file_inode(file)->i_sb);
 		ret = vfs_fsync_range(real.file, start, end, datasync);
-		revert_creds(old_cred);
+		ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 	}
 
 	fdput(real);
@@ -582,7 +583,7 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 
 	old_cred = ovl_override_creds(file_inode(file)->i_sb);
 	ret = call_mmap(vma->vm_file, vma);
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 	ovl_file_accessed(file);
 
 	return ret;
@@ -608,7 +609,7 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
 
 	old_cred = ovl_override_creds(file_inode(file)->i_sb);
 	ret = vfs_fallocate(real.file, mode, offset, len);
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 
 	/* Update size */
 	ovl_file_modified(file);
@@ -633,7 +634,7 @@ static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
 
 	old_cred = ovl_override_creds(file_inode(file)->i_sb);
 	ret = vfs_fadvise(real.file, offset, len, advice);
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 
 	fdput(real);
 
@@ -692,7 +693,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
 						flags);
 		break;
 	}
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file_out)->i_sb, old_cred);
 
 	/* Update size */
 	ovl_file_modified(file_out);
@@ -754,7 +755,7 @@ static int ovl_flush(struct file *file, fl_owner_t id)
 	if (real.file->f_op->flush) {
 		old_cred = ovl_override_creds(file_inode(file)->i_sb);
 		err = real.file->f_op->flush(real.file, id);
-		revert_creds(old_cred);
+		ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 	}
 	fdput(real);
 
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -81,7 +81,7 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		inode_lock(upperdentry->d_inode);
 		old_cred = ovl_override_creds(dentry->d_sb);
 		err = ovl_do_notify_change(ofs, upperdentry, attr);
-		revert_creds(old_cred);
+		ovl_revert_creds(dentry->d_sb, old_cred);
 		if (!err)
 			ovl_copyattr(dentry->d_inode);
 		inode_unlock(upperdentry->d_inode);
@@ -281,7 +281,7 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
 		stat->nlink = dentry->d_inode->i_nlink;
 
 out:
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 
 	return err;
 }
@@ -318,7 +318,7 @@ int ovl_permission(struct mnt_idmap *idmap,
 		mask |= MAY_READ;
 	}
 	err = inode_permission(mnt_idmap(realpath.mnt), realinode, mask);
-	revert_creds(old_cred);
+	ovl_revert_creds(inode->i_sb, old_cred);
 
 	return err;
 }
@@ -335,7 +335,7 @@ static const char *ovl_get_link(struct dentry *dentry,
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	p = vfs_get_link(ovl_dentry_real(dentry), done);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	return p;
 }
 
@@ -470,7 +470,7 @@ struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
 
 		old_cred = ovl_override_creds(inode->i_sb);
 		acl = ovl_get_acl_path(&realpath, posix_acl_xattr_name(type), noperm);
-		revert_creds(old_cred);
+		ovl_revert_creds(inode->i_sb, old_cred);
 	}
 
 	return acl;
@@ -499,7 +499,7 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
 		old_cred = ovl_override_creds(dentry->d_sb);
 		real_acl = vfs_get_acl(mnt_idmap(realpath.mnt), realdentry,
 				       acl_name);
-		revert_creds(old_cred);
+		ovl_revert_creds(dentry->d_sb, old_cred);
 		if (IS_ERR(real_acl)) {
 			err = PTR_ERR(real_acl);
 			goto out;
@@ -524,7 +524,7 @@ static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
 		err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
 	else
 		err = ovl_do_remove_acl(ofs, realdentry, acl_name);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	ovl_drop_write(dentry);
 
 	/* copy c/mtime */
@@ -601,7 +601,7 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 
 	old_cred = ovl_override_creds(inode->i_sb);
 	err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
-	revert_creds(old_cred);
+	ovl_revert_creds(inode->i_sb, old_cred);
 
 	return err;
 }
@@ -672,7 +672,7 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
 		err = ovl_set_protattr(inode, upperpath.dentry, fa);
 		if (!err)
 			err = ovl_real_fileattr_set(&upperpath, fa);
-		revert_creds(old_cred);
+		ovl_revert_creds(inode->i_sb, old_cred);
 		ovl_drop_write(dentry);
 
 		/*
@@ -734,7 +734,7 @@ int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 	old_cred = ovl_override_creds(inode->i_sb);
 	err = ovl_real_fileattr_get(&realpath, fa);
 	ovl_fileattr_prot_flags(inode, fa);
-	revert_creds(old_cred);
+	ovl_revert_creds(inode->i_sb, old_cred);
 
 	return err;
 }
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -986,7 +986,7 @@ static int ovl_maybe_lookup_lowerdata(struct dentry *dentry)
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	err = ovl_lookup_data_layers(dentry, redirect, &datapath);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	if (err)
 		goto out_err;
 
@@ -1331,7 +1331,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 
 	ovl_dentry_init_reval(dentry, upperdentry, OVL_I_E(inode));
 
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	if (origin_path) {
 		dput(origin_path->dentry);
 		kfree(origin_path);
@@ -1355,7 +1355,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	kfree(upperredirect);
 out:
 	kfree(d.redirect);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	return ERR_PTR(err);
 }
 
@@ -1412,7 +1412,7 @@ bool ovl_lower_positive(struct dentry *dentry)
 			dput(this);
 		}
 	}
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 
 	return positive;
 }
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -417,6 +417,7 @@ int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
 struct dentry *ovl_workdir(struct dentry *dentry);
 const struct cred *ovl_override_creds(struct super_block *sb);
+void ovl_revert_creds(struct super_block *sb, const struct cred *oldcred);
 int ovl_can_decode_fh(struct super_block *sb);
 struct dentry *ovl_indexdir(struct super_block *sb);
 bool ovl_index_all(struct super_block *sb);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -19,6 +19,7 @@ struct ovl_config {
 	bool metacopy;
 	bool userxattr;
 	bool ovl_volatile;
+	bool override_creds;
 };
 
 struct ovl_sb {
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -43,6 +43,11 @@ module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
 MODULE_PARM_DESC(metacopy,
 		 "Default to on or off for the metadata only copy up feature");
 
+static bool __read_mostly ovl_override_creds_def = true;
+module_param_named(override_creds, ovl_override_creds_def, bool, 0644);
+MODULE_PARM_DESC(ovl_override_creds_def,
+		 "Use mounter's credentials for accesses");
+
 enum ovl_opt {
 	Opt_lowerdir,
 	Opt_lowerdir_add,
@@ -59,6 +64,7 @@ enum ovl_opt {
 	Opt_metacopy,
 	Opt_verity,
 	Opt_volatile,
+	Opt_override_creds,
 };
 
 static const struct constant_table ovl_parameter_bool[] = {
@@ -159,6 +165,7 @@ const struct fs_parameter_spec ovl_parameter_spec[] = {
 	fsparam_enum("metacopy",            Opt_metacopy, ovl_parameter_bool),
 	fsparam_enum("verity",              Opt_verity, ovl_parameter_verity),
 	fsparam_flag("volatile",            Opt_volatile),
+	fsparam_enum("override_creds",      Opt_override_creds, ovl_parameter_bool),
 	{}
 };
 
@@ -620,6 +627,9 @@ static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param)
 	case Opt_userxattr:
 		config->userxattr = true;
 		break;
+	case Opt_override_creds:
+		config->override_creds = result.uint_32;
+		break;
 	default:
 		pr_err("unrecognized mount option \"%s\" or missing value\n",
 		       param->key);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -290,7 +290,7 @@ static int ovl_check_whiteouts(const struct path *path, struct ovl_readdir_data
 		}
 		inode_unlock(dir->d_inode);
 	}
-	revert_creds(old_cred);
+	ovl_revert_creds(rdd->dentry->d_sb, old_cred);
 
 	return err;
 }
@@ -807,7 +807,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
 	}
 	err = 0;
 out:
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	return err;
 }
 
@@ -859,7 +859,7 @@ static struct file *ovl_dir_open_realfile(const struct file *file,
 
 	old_cred = ovl_override_creds(file_inode(file)->i_sb);
 	res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
-	revert_creds(old_cred);
+	ovl_revert_creds(file_inode(file)->i_sb, old_cred);
 
 	return res;
 }
@@ -986,7 +986,7 @@ int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
 
 	old_cred = ovl_override_creds(dentry->d_sb);
 	err = ovl_dir_read_merged(dentry, list, &root);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	if (err)
 		return err;
 
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -65,9 +65,18 @@ const struct cred *ovl_override_creds(struct super_block *sb)
 {
 	struct ovl_fs *ofs = OVL_FS(sb);
 
+	if (!ofs->config.override_creds)
+		return NULL;
 	return override_creds(ofs->creator_cred);
 }
 
+void ovl_revert_creds(struct super_block *sb, const struct cred *old_cred)
+{
+	if (old_cred)
+		revert_creds(old_cred);
+}
+
+
 /*
  * Check if underlying fs supports file handles and try to determine encoding
  * type, in order to deduce maximum inode number used by fs.
@@ -1165,7 +1174,7 @@ int ovl_nlink_start(struct dentry *dentry)
 	 * value relative to the upper inode nlink in an upper inode xattr.
 	 */
 	err = ovl_set_nlink_upper(dentry);
-	revert_creds(old_cred);
+	ovl_revert_creds(dentry->d_sb, old_cred);
 	if (err)
 		goto out_drop_write;
 
@@ -1190,7 +1199,7 @@ void ovl_nlink_end(struct dentry *dentry)
 
 		old_cred = ovl_override_creds(dentry->d_sb);
 		ovl_cleanup_index(dentry);
-		revert_creds(old_cred);
+		ovl_revert_creds(dentry->d_sb, old_cred);
 	}
 
 	ovl_inode_unlock(inode);