1 files changed, 191 insertions, 173 deletions

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index d21f81a524f6..06b860b9ded6 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -105,7 +105,7 @@ static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
 			whiteout = dget(link);
 		end_creating(link);
 		if (!err)
-			return whiteout;;
+			return whiteout;
 
 		if (err != -EMLINK) {
 			pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%u)\n",
@@ -581,59 +581,69 @@ out_cleanup_unlocked:
 	goto out_dput;
 }
 
-static const struct cred *ovl_setup_cred_for_create(struct dentry *dentry,
-						    struct inode *inode,
-						    umode_t mode,
-						    const struct cred *old_cred)
+static const struct cred *ovl_override_creator_creds(struct dentry *dentry, struct inode *inode, umode_t mode)
 {
 	int err;
-	struct cred *override_cred;
 
-	override_cred = prepare_creds();
+	if (WARN_ON_ONCE(current->cred != ovl_creds(dentry->d_sb)))
+		return ERR_PTR(-EINVAL);
+
+	CLASS(prepare_creds, override_cred)();
 	if (!override_cred)
 		return ERR_PTR(-ENOMEM);
 
 	override_cred->fsuid = inode->i_uid;
 	override_cred->fsgid = inode->i_gid;
+
 	err = security_dentry_create_files_as(dentry, mode, &dentry->d_name,
-					      old_cred, override_cred);
-	if (err) {
-		put_cred(override_cred);
+					      current->cred, override_cred);
+	if (err)
 		return ERR_PTR(err);
-	}
 
-	/*
-	 * Caller is going to match this with revert_creds() and drop
-	 * referenec on the returned creds.
-	 * We must be called with creator creds already, otherwise we risk
-	 * leaking creds.
-	 */
-	old_cred = override_creds(override_cred);
-	WARN_ON_ONCE(old_cred != ovl_creds(dentry->d_sb));
+	return override_creds(no_free_ptr(override_cred));
+}
+
+static void ovl_revert_creator_creds(const struct cred *old_cred)
+{
+	const struct cred *override_cred;
 
-	return override_cred;
+	override_cred = revert_creds(old_cred);
+	put_cred(override_cred);
+}
+
+DEFINE_CLASS(ovl_override_creator_creds,
+	     const struct cred *,
+	     if (!IS_ERR_OR_NULL(_T)) ovl_revert_creator_creds(_T),
+	     ovl_override_creator_creds(dentry, inode, mode),
+	     struct dentry *dentry, struct inode *inode, umode_t mode)
+
+static int ovl_create_handle_whiteouts(struct dentry *dentry,
+				       struct inode *inode,
+				       struct ovl_cattr *attr)
+{
+	if (!ovl_dentry_is_whiteout(dentry))
+		return ovl_create_upper(dentry, inode, attr);
+
+	return ovl_create_over_whiteout(dentry, inode, attr);
 }
 
 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, *new_cred = NULL;
 	struct dentry *parent = dentry->d_parent;
 
-	old_cred = ovl_override_creds(dentry->d_sb);
-
-	/*
-	 * When linking a file with copy up origin into a new parent, mark the
-	 * new parent dir "impure".
-	 */
-	if (origin) {
-		err = ovl_set_impure(parent, ovl_dentry_upper(parent));
-		if (err)
-			goto out_revert_creds;
-	}
+	with_ovl_creds(dentry->d_sb) {
+		/*
+		 * When linking a file with copy up origin into a new parent, mark the
+		 * new parent dir "impure".
+		 */
+		if (origin) {
+			err = ovl_set_impure(parent, ovl_dentry_upper(parent));
+			if (err)
+				return err;
+		}
 
-	if (!attr->hardlink) {
 		/*
 		 * In the creation cases(create, mkdir, mknod, symlink),
 		 * ovl should transfer current's fs{u,g}id to underlying
@@ -647,23 +657,16 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
 		 * create a new inode, so just use the ovl mounter's
 		 * fs{u,g}id.
 		 */
-		new_cred = ovl_setup_cred_for_create(dentry, inode, attr->mode,
-						     old_cred);
-		err = PTR_ERR(new_cred);
-		if (IS_ERR(new_cred)) {
-			new_cred = NULL;
-			goto out_revert_creds;
-		}
-	}
 
-	if (!ovl_dentry_is_whiteout(dentry))
-		err = ovl_create_upper(dentry, inode, attr);
-	else
-		err = ovl_create_over_whiteout(dentry, inode, attr);
+		if (attr->hardlink)
+			return ovl_create_handle_whiteouts(dentry, inode, attr);
 
-out_revert_creds:
-	ovl_revert_creds(old_cred);
-	put_cred(new_cred);
+		scoped_class(ovl_override_creator_creds, cred, dentry, inode, attr->mode) {
+			if (IS_ERR(cred))
+				return PTR_ERR(cred);
+			return ovl_create_handle_whiteouts(dentry, inode, attr);
+		}
+	}
 	return err;
 }
 
@@ -739,14 +742,8 @@ static int ovl_symlink(struct mnt_idmap *idmap, struct inode *dir,
 
 static int ovl_set_link_redirect(struct dentry *dentry)
 {
-	const struct cred *old_cred;
-	int err;
-
-	old_cred = ovl_override_creds(dentry->d_sb);
-	err = ovl_set_redirect(dentry, false);
-	ovl_revert_creds(old_cred);
-
-	return err;
+	with_ovl_creds(dentry->d_sb)
+		return ovl_set_redirect(dentry, false);
 }
 
 static int ovl_link(struct dentry *old, struct inode *newdir,
@@ -921,7 +918,6 @@ static void ovl_drop_nlink(struct dentry *dentry)
 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 {
 	int err;
-	const struct cred *old_cred;
 	bool lower_positive = ovl_lower_positive(dentry);
 	LIST_HEAD(list);
 
@@ -940,12 +936,12 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 	if (err)
 		goto out;
 
-	old_cred = ovl_override_creds(dentry->d_sb);
-	if (!lower_positive)
-		err = ovl_remove_upper(dentry, is_dir, &list);
-	else
-		err = ovl_remove_and_whiteout(dentry, &list);
-	ovl_revert_creds(old_cred);
+	with_ovl_creds(dentry->d_sb) {
+		if (!lower_positive)
+			err = ovl_remove_upper(dentry, is_dir, &list);
+		else
+			err = ovl_remove_and_whiteout(dentry, &list);
+	}
 	if (!err) {
 		if (is_dir)
 			clear_nlink(dentry->d_inode);
@@ -1109,101 +1105,107 @@ static int ovl_set_redirect(struct dentry *dentry, bool samedir)
 	return err;
 }
 
-static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
-		      struct dentry *old, struct inode *newdir,
-		      struct dentry *new, unsigned int flags)
+struct ovl_renamedata {
+	struct renamedata;
+	struct dentry *opaquedir;
+	bool cleanup_whiteout;
+	bool update_nlink;
+	bool overwrite;
+};
+
+static int ovl_rename_start(struct ovl_renamedata *ovlrd, struct list_head *list)
 {
-	int err;
-	struct dentry *old_upperdir;
-	struct dentry *new_upperdir;
-	struct renamedata rd = {};
-	bool old_opaque;
-	bool new_opaque;
-	bool cleanup_whiteout = false;
-	bool update_nlink = false;
-	bool overwrite = !(flags & RENAME_EXCHANGE);
+	struct dentry *old = ovlrd->old_dentry;
+	struct dentry *new = ovlrd->new_dentry;
 	bool is_dir = d_is_dir(old);
 	bool new_is_dir = d_is_dir(new);
-	bool samedir = olddir == newdir;
-	struct dentry *opaquedir = NULL;
-	struct dentry *whiteout = NULL;
-	const struct cred *old_cred = NULL;
-	struct ovl_fs *ofs = OVL_FS(old->d_sb);
-	LIST_HEAD(list);
+	int err;
 
-	err = -EINVAL;
-	if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
-		goto out;
+	if (ovlrd->flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
+		return -EINVAL;
 
-	flags &= ~RENAME_NOREPLACE;
+	ovlrd->flags &= ~RENAME_NOREPLACE;
 
 	/* Don't copy up directory trees */
 	err = -EXDEV;
 	if (!ovl_can_move(old))
-		goto out;
-	if (!overwrite && !ovl_can_move(new))
-		goto out;
+		return err;
+	if (!ovlrd->overwrite && !ovl_can_move(new))
+		return err;
 
-	if (overwrite && new_is_dir && !ovl_pure_upper(new)) {
-		err = ovl_check_empty_dir(new, &list);
+	if (ovlrd->overwrite && new_is_dir && !ovl_pure_upper(new)) {
+		err = ovl_check_empty_dir(new, list);
 		if (err)
-			goto out;
+			return err;
 	}
 
-	if (overwrite) {
+	if (ovlrd->overwrite) {
 		if (ovl_lower_positive(old)) {
 			if (!ovl_dentry_is_whiteout(new)) {
 				/* Whiteout source */
-				flags |= RENAME_WHITEOUT;
+				ovlrd->flags |= RENAME_WHITEOUT;
 			} else {
 				/* Switch whiteouts */
-				flags |= RENAME_EXCHANGE;
+				ovlrd->flags |= RENAME_EXCHANGE;
 			}
 		} else if (is_dir && ovl_dentry_is_whiteout(new)) {
-			flags |= RENAME_EXCHANGE;
-			cleanup_whiteout = true;
+			ovlrd->flags |= RENAME_EXCHANGE;
+			ovlrd->cleanup_whiteout = true;
 		}
 	}
 
 	err = ovl_copy_up(old);
 	if (err)
-		goto out;
+		return err;
 
 	err = ovl_copy_up(new->d_parent);
 	if (err)
-		goto out;
-	if (!overwrite) {
+		return err;
+
+	if (!ovlrd->overwrite) {
 		err = ovl_copy_up(new);
 		if (err)
-			goto out;
+			return err;
 	} else if (d_inode(new)) {
 		err = ovl_nlink_start(new);
 		if (err)
-			goto out;
+			return err;
 
-		update_nlink = true;
+		ovlrd->update_nlink = true;
 	}
 
-	if (!update_nlink) {
+	if (!ovlrd->update_nlink) {
 		/* ovl_nlink_start() took ovl_want_write() */
 		err = ovl_want_write(old);
 		if (err)
-			goto out;
+			return err;
 	}
 
-	old_cred = ovl_override_creds(old->d_sb);
+	return 0;
+}
 
-	if (!list_empty(&list)) {
-		opaquedir = ovl_clear_empty(new, &list);
-		err = PTR_ERR(opaquedir);
-		if (IS_ERR(opaquedir)) {
-			opaquedir = NULL;
-			goto out_revert_creds;
-		}
-	}
+static int ovl_rename_upper(struct ovl_renamedata *ovlrd, struct list_head *list)
+{
+	struct dentry *old = ovlrd->old_dentry;
+	struct dentry *new = ovlrd->new_dentry;
+	struct ovl_fs *ofs = OVL_FS(old->d_sb);
+	struct dentry *old_upperdir = ovl_dentry_upper(old->d_parent);
+	struct dentry *new_upperdir = ovl_dentry_upper(new->d_parent);
+	bool is_dir = d_is_dir(old);
+	bool new_is_dir = d_is_dir(new);
+	bool samedir = old->d_parent == new->d_parent;
+	struct renamedata rd = {};
+	struct dentry *de;
+	struct dentry *whiteout = NULL;
+	bool old_opaque, new_opaque;
+	int err;
 
-	old_upperdir = ovl_dentry_upper(old->d_parent);
-	new_upperdir = ovl_dentry_upper(new->d_parent);
+	if (!list_empty(list)) {
+		de = ovl_clear_empty(new, list);
+		if (IS_ERR(de))
+			return PTR_ERR(de);
+		ovlrd->opaquedir = de;
+	}
 
 	if (!samedir) {
 		/*
@@ -1215,26 +1217,25 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 		if (ovl_type_origin(old)) {
 			err = ovl_set_impure(new->d_parent, new_upperdir);
 			if (err)
-				goto out_revert_creds;
+				return err;
 		}
-		if (!overwrite && ovl_type_origin(new)) {
+		if (!ovlrd->overwrite && ovl_type_origin(new)) {
 			err = ovl_set_impure(old->d_parent, old_upperdir);
 			if (err)
-				goto out_revert_creds;
+				return err;
 		}
 	}
 
 	rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
 	rd.old_parent = old_upperdir;
 	rd.new_parent = new_upperdir;
-	rd.flags = flags;
+	rd.flags = ovlrd->flags;
 
 	err = start_renaming(&rd, 0,
 			     &QSTR_LEN(old->d_name.name, old->d_name.len),
 			     &QSTR_LEN(new->d_name.name, new->d_name.len));
-
 	if (err)
-		goto out_revert_creds;
+		return err;
 
 	err = -ESTALE;
 	if (!ovl_matches_upper(old, rd.old_dentry))
@@ -1245,8 +1246,8 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 
 	err = -ESTALE;
 	if (d_inode(new) && ovl_dentry_upper(new)) {
-		if (opaquedir) {
-			if (rd.new_dentry != opaquedir)
+		if (ovlrd->opaquedir) {
+			if (rd.new_dentry != ovlrd->opaquedir)
 				goto out_unlock;
 		} else {
 			if (!ovl_matches_upper(new, rd.new_dentry))
@@ -1257,7 +1258,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 			if (!new_opaque || !ovl_upper_is_whiteout(ofs, rd.new_dentry))
 				goto out_unlock;
 		} else {
-			if (flags & RENAME_EXCHANGE)
+			if (ovlrd->flags & RENAME_EXCHANGE)
 				goto out_unlock;
 		}
 	}
@@ -1273,9 +1274,9 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 	if (err)
 		goto out_unlock;
 
-	if (!overwrite && ovl_type_merge_or_lower(new))
+	if (!ovlrd->overwrite && ovl_type_merge_or_lower(new))
 		err = ovl_set_redirect(new, samedir);
-	else if (!overwrite && new_is_dir && !new_opaque &&
+	else if (!ovlrd->overwrite && new_is_dir && !new_opaque &&
 		 ovl_type_merge(old->d_parent))
 		err = ovl_set_opaque_xerr(new, rd.new_dentry, -EXDEV);
 	if (err)
@@ -1283,20 +1284,21 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 
 	err = ovl_do_rename_rd(&rd);
 
-	if (!err && cleanup_whiteout)
+	if (!err && ovlrd->cleanup_whiteout)
 		whiteout = dget(rd.new_dentry);
 
+out_unlock:
 	end_renaming(&rd);
 
 	if (err)
-		goto out_revert_creds;
+		return err;
 
 	if (whiteout) {
 		ovl_cleanup(ofs, old_upperdir, whiteout);
 		dput(whiteout);
 	}
 
-	if (overwrite && d_inode(new)) {
+	if (ovlrd->overwrite && d_inode(new)) {
 		if (new_is_dir)
 			clear_nlink(d_inode(new));
 		else
@@ -1304,7 +1306,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 	}
 
 	ovl_dir_modified(old->d_parent, ovl_type_origin(old) ||
-			 (!overwrite && ovl_type_origin(new)));
+			 (!ovlrd->overwrite && ovl_type_origin(new)));
 	ovl_dir_modified(new->d_parent, ovl_type_origin(old) ||
 			 (d_inode(new) && ovl_type_origin(new)));
 
@@ -1313,26 +1315,47 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
 	if (d_inode(new) && ovl_dentry_upper(new))
 		ovl_copyattr(d_inode(new));
 
-out_revert_creds:
-	ovl_revert_creds(old_cred);
-	if (update_nlink)
-		ovl_nlink_end(new);
+	return err;
+}
+
+static void ovl_rename_end(struct ovl_renamedata *ovlrd)
+{
+	if (ovlrd->update_nlink)
+		ovl_nlink_end(ovlrd->new_dentry);
 	else
-		ovl_drop_write(old);
-out:
-	dput(opaquedir);
+		ovl_drop_write(ovlrd->old_dentry);
+}
+
+static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir,
+		      struct dentry *old, struct inode *newdir,
+		      struct dentry *new, unsigned int flags)
+{
+	struct ovl_renamedata ovlrd = {
+		.old_parent		= old->d_parent,
+		.old_dentry		= old,
+		.new_parent		= new->d_parent,
+		.new_dentry		= new,
+		.flags			= flags,
+		.overwrite		= !(flags & RENAME_EXCHANGE),
+	};
+	LIST_HEAD(list);
+	int err;
+
+	err = ovl_rename_start(&ovlrd, &list);
+	if (!err) {
+		with_ovl_creds(old->d_sb)
+			err = ovl_rename_upper(&ovlrd, &list);
+		ovl_rename_end(&ovlrd);
+	}
+
+	dput(ovlrd.opaquedir);
 	ovl_cache_free(&list);
 	return err;
-
-out_unlock:
-	end_renaming(&rd);
-	goto out_revert_creds;
 }
 
 static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
 			      struct inode *inode, umode_t mode)
 {
-	const struct cred *old_cred, *new_cred = NULL;
 	struct path realparentpath;
 	struct file *realfile;
 	struct ovl_file *of;
@@ -1341,41 +1364,36 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
 	int flags = file->f_flags | OVL_OPEN_FLAGS;
 	int err;
 
-	old_cred = ovl_override_creds(dentry->d_sb);
-	new_cred = ovl_setup_cred_for_create(dentry, inode, mode, old_cred);
-	err = PTR_ERR(new_cred);
-	if (IS_ERR(new_cred)) {
-		new_cred = NULL;
-		goto out_revert_creds;
-	}
+	with_ovl_creds(dentry->d_sb) {
+		scoped_class(ovl_override_creator_creds, cred, dentry, inode, mode) {
+			if (IS_ERR(cred))
+				return PTR_ERR(cred);
 
-	ovl_path_upper(dentry->d_parent, &realparentpath);
-	realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath,
-					mode, current_cred());
-	err = PTR_ERR_OR_ZERO(realfile);
-	pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err);
-	if (err)
-		goto out_revert_creds;
+			ovl_path_upper(dentry->d_parent, &realparentpath);
+			realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath,
+							mode, current_cred());
+			err = PTR_ERR_OR_ZERO(realfile);
+			pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err);
+			if (err)
+				return err;
 
-	of = ovl_file_alloc(realfile);
-	if (!of) {
-		fput(realfile);
-		err = -ENOMEM;
-		goto out_revert_creds;
-	}
+			of = ovl_file_alloc(realfile);
+			if (!of) {
+				fput(realfile);
+				return -ENOMEM;
+			}
 
-	/* ovl_instantiate() consumes the newdentry reference on success */
-	newdentry = dget(realfile->f_path.dentry);
-	err = ovl_instantiate(dentry, inode, newdentry, false, file);
-	if (!err) {
-		file->private_data = of;
-	} else {
-		dput(newdentry);
-		ovl_file_free(of);
+			/* ovl_instantiate() consumes the newdentry reference on success */
+			newdentry = dget(realfile->f_path.dentry);
+			err = ovl_instantiate(dentry, inode, newdentry, false, file);
+			if (!err) {
+				file->private_data = of;
+			} else {
+				dput(newdentry);
+				ovl_file_free(of);
+			}
+		}
 	}
-out_revert_creds:
-	ovl_revert_creds(old_cred);
-	put_cred(new_cred);
 	return err;
 }