Re: [PATCH 04/13] overlay filesystem

Eric W. Biederman
2012-08-16T06:25:11Z

Miklos Szeredi <miklos@szeredi.hu> writes:

Minor nits below.

> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
> new file mode 100644
> index 0000000..6b50823
> --- /dev/null
> +++ b/fs/overlayfs/dir.c
> @@ -0,0 +1,598 @@
> +/*
> + *
> + * Copyright (C) 2011 Novell Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/fs.h>
> +#include <linux/namei.h>
> +#include <linux/xattr.h>
> +#include <linux/security.h>
> +#include <linux/cred.h>
> +#include "overlayfs.h"
> +
> +static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
> +
> +static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
> +{
> + int err;
> + struct dentry *newdentry;
> + const struct cred *old_cred;
> + struct cred *override_cred;
> +
> + /* FIXME: recheck lower dentry to see if whiteout is really
> needed */

Is that FIXME still valid?

> + err = -ENOMEM;
> + override_cred = prepare_creds();
> + if (!override_cred)
> + goto out;
> +
> + /*
> + * CAP_SYS_ADMIN for setxattr
> + * CAP_DAC_OVERRIDE for symlink creation
> + * CAP_FOWNER for unlink in sticky directory
> + */
> + cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
> + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
> + cap_raise(override_cred->cap_effective, CAP_FOWNER);
> + override_cred->fsuid = 0;
> + override_cred->fsgid = 0;

Could you please make these GLOBAL_ROOT_UID and GLOBAL_ROOT_GID
instead of 0? Otherwise this code won't compile with the usernamespace
bits enabled.

> + old_cred = override_creds(override_cred);

Eric