From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1FE8C34022 for ; Mon, 17 Feb 2020 16:29:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5FB522B48 for ; Mon, 17 Feb 2020 16:29:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581956956; bh=3RyDHdCvjIDVivxlLYCUY6FAPAIB2sXqUpmcgkCzhL0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=UppO4WYKcj0jVHrQPhTxzqgmdRhQEpFWZu+vjVcpiPmLSSNoTA8Qr2ePqHckAMuoF TZXmHR/4g6gtirQ8+zpD+LSDrxdQcQ4CdDmpSBh/4RPYq5KpLcrzJ0g5T5DVCCM6Nm EHBuKhNJ5YnqPU9FTxzXCsW3OQ66oamrvcxsIJG4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726891AbgBQQ3Q (ORCPT ); Mon, 17 Feb 2020 11:29:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:37220 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726873AbgBQQ3Q (ORCPT ); Mon, 17 Feb 2020 11:29:16 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 35B0A214D8; Mon, 17 Feb 2020 16:29:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581956954; bh=3RyDHdCvjIDVivxlLYCUY6FAPAIB2sXqUpmcgkCzhL0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RDAcdCoNIDDp07PhuKaqUFmG3j2kkYyX4AI8GwU+iW2xs9ifI+alAwc7jSsNjnWNC izXx4On2CO3plUbt+zfIs+pCQT1kvPFnPUUw8rglZ7wWKybI6Y0/BVULDe0zpjMXQ8 nmRLuzkDAjLOhPAHZuSzp7CyF1i7uzQHP4+XxcC8= Date: Mon, 17 Feb 2020 17:29:12 +0100 From: Greg Kroah-Hartman To: Christian Brauner Cc: "David S. Miller" , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "Rafael J. Wysocki" , Pavel Machek , Jakub Kicinski , Eric Dumazet , Stephen Hemminger , linux-pm@vger.kernel.org Subject: Re: [PATCH net-next v2 01/10] sysfs: add sysfs_file_change_owner{_by_name}() Message-ID: <20200217162912.GB1502885@kroah.com> References: <20200217161436.1748598-1-christian.brauner@ubuntu.com> <20200217161436.1748598-2-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200217161436.1748598-2-christian.brauner@ubuntu.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Mon, Feb 17, 2020 at 05:14:27PM +0100, Christian Brauner wrote: > Add helpers to change owner of a sysfs files. > The ownership of a sysfs object is determined based on the ownership of > the corresponding kobject, i.e. only if the ownership of a kobject is > changed will this function change the ownership of the corresponding > sysfs entry. > This function will be used to correctly account for kobject ownership > changes, e.g. when moving network devices between network namespaces. > > Signed-off-by: Christian Brauner > --- > /* v2 */ > - Greg Kroah-Hartman : > - Better naming for sysfs_file_change_owner() to reflect the fact that it > can be used to change the owner of the kobject itself by passing NULL as > argument. > - Christian Brauner : > - Split sysfs_file_change_owner() into two helpers sysfs_change_owner() and > sysfs_change_owner_by_name(). The former changes the owner of the kobject > itself, the latter the owner of the kobject looked up via the name > argument. > --- > fs/sysfs/file.c | 82 +++++++++++++++++++++++++++++++++++++++++++ > include/linux/sysfs.h | 14 ++++++++ > 2 files changed, 96 insertions(+) > > diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c > index 130fc6fbcc03..8f2607de2456 100644 > --- a/fs/sysfs/file.c > +++ b/fs/sysfs/file.c > @@ -558,3 +558,85 @@ void sysfs_remove_bin_file(struct kobject *kobj, > kernfs_remove_by_name(kobj->sd, attr->attr.name); > } > EXPORT_SYMBOL_GPL(sysfs_remove_bin_file); > + > +static int internal_change_owner(struct kernfs_node *kn, struct kobject *kobj) > +{ > + kuid_t uid; > + kgid_t gid; > + struct iattr newattrs = { > + .ia_valid = ATTR_UID | ATTR_GID, > + }; > + > + kobject_get_ownership(kobj, &uid, &gid); > + newattrs.ia_uid = uid; > + newattrs.ia_gid = gid; > + > + return kernfs_setattr(kn, &newattrs); > +} > + > +/** > + * sysfs_file_change_owner_by_name - change owner of a file. > + * @kobj: object. > + * @name: name of the file to change. > + * > + * To change the ownership of a sysfs object, the caller must first change the > + * uid/gid of the kobject and then call this function. Why have the caller do this? Why not pass the uid/gid as a parameter here? That would make it totally obvious as to what is happening here, right? Otherwise this function is depending on someone doing something before calling it, and that's going to be a very very hard thing to always ensure/audit. thanks, greg k-h