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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B69BC32771 for ; Wed, 28 Sep 2022 07:44:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233445AbiI1Hoc (ORCPT ); Wed, 28 Sep 2022 03:44:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233818AbiI1Hni (ORCPT ); Wed, 28 Sep 2022 03:43:38 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 842BD10D645; Wed, 28 Sep 2022 00:40:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A41C4B81E8A; Wed, 28 Sep 2022 07:40:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3C00C433D7; Wed, 28 Sep 2022 07:40:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664350835; bh=gPbGDOSS/QTrrkYZ9vASwt0DO6D8M/g3laHN6g51Hdg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LrSyo4qKiVmMLXmefSO13P9tVI/vfi24MC/PegDBJ0WEtsz7C1PikekWH3JmaBmlM rNWAuwOBf9O4T9J+NLJ2j7qtiCbUIEH4W4JsVE+0DgFbO8B3LhgLCCyunNcU/zRPce YDX5IWG8eXY7wH4is1KSDjFhwE7dHaTiCSZZquSDWzRziIdygMDPel0jZt9+AEu5RA Mi83+RmfcQay9W2ChXku+O2lXQINLA7YP7vcGpc2p4b2ohNUwf/3Q82SAcyUG30N8d U9AcPzGJCRjJlvSdx6GERObUQA3iJizetBuAjOdl6OBqwuCLN+5PWhfhGemq9OTny9 qFktB6GfGWIXQ== Date: Wed, 28 Sep 2022 09:40:30 +0200 From: Christian Brauner To: Paul Moore Cc: linux-fsdevel@vger.kernel.org, Seth Forshee , Christoph Hellwig , Al Viro , linux-security-module@vger.kernel.org Subject: Re: [PATCH v2 16/30] acl: add vfs_get_acl() Message-ID: <20220928074030.3dnytkvt7fibytlu@wittgenstein> References: <20220926140827.142806-1-brauner@kernel.org> <20220926140827.142806-17-brauner@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: On Tue, Sep 27, 2022 at 06:55:25PM -0400, Paul Moore wrote: > On Mon, Sep 26, 2022 at 11:24 AM Christian Brauner wrote: > > > > In previous patches we implemented get and set inode operations for all > > non-stacking filesystems that support posix acls but didn't yet > > implement get and/or set acl inode operations. This specifically > > affected cifs and 9p. > > > > Now we can build a posix acl api based solely on get and set inode > > operations. We add a new vfs_get_acl() api that can be used to get posix > > acls. This finally removes all type unsafety and type conversion issues > > explained in detail in [1] that we aim to get rid of. > > > > After we finished building the vfs api we can switch stacking > > filesystems to rely on the new posix api and then finally switch the > > xattr system calls themselves to rely on the posix acl api. > > > > Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] > > Signed-off-by: Christian Brauner (Microsoft) > > --- > > > > Notes: > > /* v2 */ > > unchanged > > > > fs/posix_acl.c | 131 ++++++++++++++++++++++++++++++-- > > include/linux/posix_acl.h | 9 +++ > > include/linux/posix_acl_xattr.h | 10 +++ > > 3 files changed, 142 insertions(+), 8 deletions(-) > > ... > > > diff --git a/fs/posix_acl.c b/fs/posix_acl.c > > index ef0908a4bc46..18873be583a9 100644 > > --- a/fs/posix_acl.c > > +++ b/fs/posix_acl.c > > @@ -1369,3 +1439,48 @@ int vfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, > > return error; > > } > > EXPORT_SYMBOL(vfs_set_acl); > > + > > +/** > > + * vfs_get_acl - get posix acls > > + * @mnt_userns: user namespace of the mount > > + * @dentry: the dentry based on which to retrieve the posix acls > > + * @acl_name: the name of the posix acl > > + * > > + * This function retrieves @kacl from the filesystem. The caller must all > > + * posix_acl_release() on @kacl. > > + * > > + * Return: On success POSIX ACLs in VFS format, on error negative errno. > > + */ > > +struct posix_acl *vfs_get_acl(struct user_namespace *mnt_userns, > > + struct dentry *dentry, const char *acl_name) > > +{ > > + struct inode *inode = d_inode(dentry); > > + struct posix_acl *acl; > > + int acl_type, error; > > + > > + acl_type = posix_acl_type(acl_name); > > + if (acl_type < 0) > > + return ERR_PTR(-EINVAL); > > + > > + /* > > + * The VFS has no restrictions on reading POSIX ACLs so calling > > + * something like xattr_permission() isn't needed. Only LSMs get a say. > > + */ > > + error = security_inode_getxattr(dentry, acl_name); > > + if (error) > > + return ERR_PTR(error); > > I understand the desire to reuse the security_inode_getxattr() hook > here, it makes perfect sense, but given that this patchset introduces > an ACL specific setter hook I think it makes sense to have a matching > getter hook. It's arguably a little silly given the current crop of > LSMs and their approach to ACLs, but if we are going to differentiate > on the write side I think we might as well be consistent and > differentiate on the read side as well. Sure, I don't mind doing that. I'll add the infrastructure and then the individual LSMs can add their own hooks.