From 38b78a5f18584db6fa7441e0f4531b283b0e6725 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 11 May 2016 01:16:37 +0200 Subject: ovl: ignore permissions on underlying lookup MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Generally permission checking is not necessary when overlayfs looks up a dentry on one of the underlying layers, since search permission on base directory was already checked in ovl_permission(). More specifically using lookup_one_len() causes a problem when the lower directory lacks search permission for a specific user while the upper directory does have search permission. Since lookups are cached, this causes inconsistency in behavior: success depends on who did the first lookup. So instead use lookup_hash() which doesn't do the permission check. Reported-by: Ignacy Gawędzki Signed-off-by: Miklos Szeredi diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 5d972e6..791235e 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -411,9 +411,7 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir, { struct dentry *dentry; - inode_lock(dir->d_inode); - dentry = lookup_one_len(name->name, dir, name->len); - inode_unlock(dir->d_inode); + dentry = lookup_hash(name, dir); if (IS_ERR(dentry)) { if (PTR_ERR(dentry) == -ENOENT) -- cgit v0.10.2