ovl: don't traverse automount points (a6f15d9a) · Commits · 戴 / test

NFS and other distributed filesystems may place automount points in the tree. Previoulsy overlayfs refused to mount such filesystems types (based on the existence of the .d_automount callback), even if the actual export didn't have any automount points. It cannot be determined in advance whether the filesystem has automount points or not. The solution is to allow fs with .d_automount but refuse to traverse any automount points encountered. Signed-off-by:

Miklos Szeredi <mszeredi@suse.cz>

fs/overlayfs/super.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -303,6 +303,10 @@ static inline struct dentry ovl_lookup_real(struct dentry dir,
		} else if (!dentry->d_inode) {
		dput(dentry);
		dentry = NULL;
		} else if (dentry->d_flags & DCACHE_MANAGED_DENTRY) {
		dput(dentry);
		/* Don't support traversing automounts */
		dentry = ERR_PTR(-EREMOTE);
		}
		return dentry;
		}
		@@ -700,12 +704,12 @@ static bool ovl_is_allowed_fs_type(struct dentry *root)

		/*
		* We don't support:
		* - automount filesystems
		* - autofs
		* - filesystems with revalidate (FIXME for lower layer)
		* - filesystems with case insensitive names
		*/
		if (dop &&
		(dop->d_manage \|\| dop->d_automount \|\|
		(dop->d_manage \|\|
		dop->d_revalidate \|\| dop->d_weak_revalidate \|\|
		dop->d_compare \|\| dop->d_hash)) {
		return false;

Admin message