From: Miklos Szeredi Date: Tue, 10 May 2016 23:16:37 +0000 (+0200) Subject: ovl: ignore permissions on underlying lookup X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=38b78a5f18584db6fa7441e0f4531b283b0e6725;p=openwrt%2Fstaging%2Fblogic.git ovl: ignore permissions on underlying lookup 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 5d972e6cd3fe..791235e03d17 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)