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 DD1A6C6FA82 for ; Tue, 27 Sep 2022 22:55:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231761AbiI0Wzl (ORCPT ); Tue, 27 Sep 2022 18:55:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231312AbiI0Wzi (ORCPT ); Tue, 27 Sep 2022 18:55:38 -0400 Received: from mail-oi1-x22d.google.com (mail-oi1-x22d.google.com [IPv6:2607:f8b0:4864:20::22d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80D9E719AE for ; Tue, 27 Sep 2022 15:55:37 -0700 (PDT) Received: by mail-oi1-x22d.google.com with SMTP id m81so13585635oia.1 for ; Tue, 27 Sep 2022 15:55:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=paul-moore-com.20210112.gappssmtp.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date; bh=0dKIPiA3h3dTDTVddQ4V1TbvxqYxwlHOgxPm+H9dxCc=; b=CMb00Ya5CzSCl2dFciNJgV7Oh9fQw8TZmymZ9hTPy8WERwyinnnVNrhAHAXUPwUNYF ev5JKKpdsoQiMVyNTPUknJNtlSVjxBD6c7nOsJG5pHSmlzkiMwiC5UZfIUUWj1irEg2c GfTtaKe9z8N1WqZDcFXHmCrQthZhVgJhSvW+Osa0DypQiVooKF4ORPITEozr28DcJENW 4xn2jS4cafTFIyjBHBE0bqvbZtBkEF37HekCT4wprh9VqYlOjxd/Tkuae78/PuB/8YrT qsPtODagZTC6hnjA7M4rtnlqSQWSxj1+cleA+8be9p50ucsz3I42sfKXPqHblpBA7kBr uu8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date; bh=0dKIPiA3h3dTDTVddQ4V1TbvxqYxwlHOgxPm+H9dxCc=; b=vPCeuCo7CZmTLPiQRk3OksszFerMnXQ7mhf2fBLq4WjEcTmQjKIObXYdPjcRHLPTM7 NGJ2M2vUAKR8obzv8GHjNw1Br3eio/HcuI38UzunPGzLacbV9sgQjhMY/zYF+gpCxSeV uf0+MLtFZn5/yqwoSAVF4idp1rtx97h5bjPD8rzQvF+5yaT4s6D7gX4GgIGhnZGoyBw0 y16a8rwNFU3lP5w+BNsN5dhcHkfY7Q8yobJ5BeAZjaF8bgMyQoobi4kkLVK6dPeMcQgi nT2lltvXnBEnzzSOVC3u5AsdIFRDhmu8XTIiSA41uoJQilZXgVp9oyS6ufYISVPDoyEi fOVw== X-Gm-Message-State: ACrzQf0HZnfJp+f8YlfViIyHycbm/jhqc7Tj+COWCDCcyOlmjU+uifvY 3wMmiOXKh3JcTluxM/x+1HQVx1W41d9sDdfKfTW/ X-Google-Smtp-Source: AMsMyM5bFev165GgI3qrOmaDNBkcJclRJwSLZNBj6+RTRBjtHySeid26mTDZWPez3QJ2NvZxo6E9O8P4HAZohjTvyzU= X-Received: by 2002:aca:1c13:0:b0:350:ce21:a022 with SMTP id c19-20020aca1c13000000b00350ce21a022mr2944496oic.172.1664319336690; Tue, 27 Sep 2022 15:55:36 -0700 (PDT) MIME-Version: 1.0 References: <20220926140827.142806-1-brauner@kernel.org> <20220926140827.142806-17-brauner@kernel.org> In-Reply-To: <20220926140827.142806-17-brauner@kernel.org> From: Paul Moore Date: Tue, 27 Sep 2022 18:55:25 -0400 Message-ID: Subject: Re: [PATCH v2 16/30] acl: add vfs_get_acl() To: Christian Brauner Cc: linux-fsdevel@vger.kernel.org, Seth Forshee , Christoph Hellwig , Al Viro , linux-security-module@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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. > + if (!IS_POSIXACL(inode)) > + return ERR_PTR(-EOPNOTSUPP); > + if (S_ISLNK(inode->i_mode)) > + return ERR_PTR(-EOPNOTSUPP); > + > + acl = __get_acl(mnt_userns, dentry, inode, acl_type); > + if (IS_ERR(acl)) > + return acl; > + if (!acl) > + return ERR_PTR(-ENODATA); > + > + return acl; > +} > +EXPORT_SYMBOL(vfs_get_acl); -- paul-moore.com