ovl: do not cleanup unsupported index entries (fa0096e3) · Commits · 戴 / test

With index=on, ovl_indexdir_cleanup() tries to cleanup invalid index entries (e.g. bad index name). This behavior could result in cleaning of entries created by newer kernels and is therefore undesirable. Instead, abort mount if such entries are encountered. We still cleanup 'stale' entries and 'orphan' entries, both those cases can be a result of offline changes to lower and upper dirs. When encoutering an index entry of type directory or whiteout, kernel was supposed to fallback to read-only mount, but the fill_super() operation returns EROFS in this case instead of returning success with read-only mount flag, so mount fails when encoutering directory or whiteout index entries. Bless this behavior by returning -EINVAL on directory and whiteout index entries as we do for all unsupported index entries. Fixes: ("ovl: do not cleanup directory and whiteout index..") Cc: <stable@vger.kernel.org> # v4.13 Signed-off-by:

Amir Goldstein <amir73il@gmail.com>

fs/overlayfs/namei.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -405,14 +405,13 @@ int ovl_verify_index(struct dentry index, struct path lowerstack,
		* be treated as stale (i.e. after unlink of the overlay inode).
		* We don't know the verification rules for directory and whiteout
		* index entries, because they have not been implemented yet, so return
		* EROFS if those entries are found to avoid corrupting an index that
		* was created by a newer kernel.
		* EINVAL if those entries are found to abort the mount to avoid
		* corrupting an index that was created by a newer kernel.
		*/
		err = -EROFS;
		err = -EINVAL;
		if (d_is_dir(index) \|\| ovl_is_whiteout(index))
		goto fail;

		err = -EINVAL;
		if (index->d_name.len < sizeof(struct ovl_fh)*2)
		goto fail;

fs/overlayfs/readdir.c

+5 −6

Original line number	Diff line number	Diff line
		@@ -1021,13 +1021,12 @@ int ovl_indexdir_cleanup(struct dentry dentry, struct vfsmount mnt,
		break;
		}
		err = ovl_verify_index(index, lowerstack, numlower);
		if (err) {
		if (err == -EROFS)
		break;
		/* Cleanup stale and orphan index entries */
		if (err && (err == -ESTALE \|\| err == -ENOENT))
		err = ovl_cleanup(dir, index);
		if (err)
		break;
		}

		dput(index);
		index = NULL;
		}

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