Re: [PATCH v16 09/12] namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2019-11-16 01:06:39
Also in:
linux-alpha, linux-arch, linuxppc-dev
On Sat, Nov 16, 2019 at 11:27:59AM +1100, Aleksa Sarai wrote:
+ if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
+ bool m_retry = read_seqretry(&mount_lock, nd->m_seq);
+ bool r_retry = read_seqretry(&rename_lock, nd->r_seq);
+
+ /*
+ * If there was a racing rename or mount along our
+ * path, then we can't be sure that ".." hasn't jumped
+ * above nd->root (and so userspace should retry or use
+ * some fallback).
+ */
+ if (unlikely(m_retry || r_retry))
+ return -EAGAIN;
+ }
}
return 0;Elaborate... Do these boolean variables make any sense now, really?