From patchwork Mon Sep 26 14:08:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12988903 X-Patchwork-Delegate: paul@paul-moore.com 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 ECC70C6FA83 for ; Mon, 26 Sep 2022 15:23:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236024AbiIZPXT (ORCPT ); Mon, 26 Sep 2022 11:23:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236349AbiIZPWb (ORCPT ); Mon, 26 Sep 2022 11:22:31 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CAF7385FA6; Mon, 26 Sep 2022 07:08:54 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 8021760E09; Mon, 26 Sep 2022 14:08:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56B80C433B5; Mon, 26 Sep 2022 14:08:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664201332; bh=Y7LLuAm58rbroIxKugjEdBdx7BJB6UX6BjlBapvOkcI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AJ8dhBsgeqJwnRg5so3uNxZ3Z7/OC1qfZ/QJycxsFULagw7GVn09gBOOcEL5Vgv7L +i6SxPSH+I+Xme9hQOYnuTiPrm85IlULCdpTr6SO1SBC9+l3T01WyM5WeGqszPXGAM qEzTxoPkXfOnvCaQgWCl2HlAWmYsWSmOeJkR3r2RpfH5IMhJU68L9jvJbqqeuYNmRx e809EEzsah6mH7ln8PQuhgb1c+zEGcB1crgBCKwkTWaWevV2mcHCo75DOU93haC0E7 tnmhV8jzSsvAD7tOFZgsTZlxJN+NmFejcECRkmp9IEvLuWF9iQr+zN2B3frah9BCNy q/DaTk6ke4DMw== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Christian Brauner , Seth Forshee , Christoph Hellwig , Al Viro , linux-security-module@vger.kernel.org Subject: [PATCH v2 04/30] fs: add new get acl method Date: Mon, 26 Sep 2022 16:08:01 +0200 Message-Id: <20220926140827.142806-5-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220926140827.142806-1-brauner@kernel.org> References: <20220926140827.142806-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3959; i=brauner@kernel.org; h=from:subject; bh=Y7LLuAm58rbroIxKugjEdBdx7BJB6UX6BjlBapvOkcI=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSQbbrLj+yn55bNFYNPsybN7mYLXzeg6kLlIXbxVv2byAZu6 mcelO0pZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACbSb8fwVyRH8rapOdsjp1yHB18eLF FLTb81l//bh1mHnu8QCtY6lcHwh2sf2wEPrQfi5Vts1d3k/k/J8F9W5PQj6OvxyoQ7xus3cgEA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. Since some filesystem rely on the dentry being available to them when setting posix acls (e.g., 9p and cifs) they cannot rely on the old get acl inode operation to retrieve posix acl and need to implement their own custom handlers because of that. In a previous patch we renamed the old get acl inode operation to ->get_inode_acl(). We decided to rename it and implement a new one since ->get_inode_acl() is called generic_permission() and inode_permission() both of which can be called during an filesystem's ->permission() handler. So simply passing a dentry argument to ->get_acl() would have amounted to also having to pass a dentry argument to ->permission(). We avoided that change. This adds a new ->get_acl() inode operations which takes a dentry argument which filesystems such as 9p, cifs, and overlayfs can implement to get posix acls. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Signed-off-by: Christian Brauner (Microsoft) --- Notes: /* v2 */ unchanged Documentation/filesystems/locking.rst | 2 ++ Documentation/filesystems/vfs.rst | 1 + include/linux/fs.h | 2 ++ 3 files changed, 5 insertions(+) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index 1cd2930e54ee..4a0fcaeec58c 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -83,6 +83,7 @@ prototypes:: int (*fileattr_set)(struct user_namespace *mnt_userns, struct dentry *dentry, struct fileattr *fa); int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa); + struct posix_acl * (*get_acl)(struct user_namespace *, struct dentry *, int); locking rules: all may block @@ -104,6 +105,7 @@ get_link: no setattr: exclusive permission: no (may not block if called in rcu-walk mode) get_inode_acl: no +get_acl: no getattr: no listxattr: no fiemap: no diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index 4fc6f1e23012..344f5f421c64 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -440,6 +440,7 @@ As of kernel 2.6.22, the following members are defined: int (*atomic_open)(struct inode *, struct dentry *, struct file *, unsigned open_flag, umode_t create_mode); int (*tmpfile) (struct user_namespace *, struct inode *, struct dentry *, umode_t); + struct posix_acl * (*get_acl)(struct user_namespace *, struct dentry *, int); int (*set_acl)(struct user_namespace *, struct inode *, struct posix_acl *, int); int (*fileattr_set)(struct user_namespace *mnt_userns, struct dentry *dentry, struct fileattr *fa); diff --git a/include/linux/fs.h b/include/linux/fs.h index 11cddd040578..badff81b9dde 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2168,6 +2168,8 @@ struct inode_operations { umode_t create_mode); int (*tmpfile) (struct user_namespace *, struct inode *, struct dentry *, umode_t); + struct posix_acl *(*get_acl)(struct user_namespace *, struct dentry *, + int); int (*set_acl)(struct user_namespace *, struct dentry *, struct posix_acl *, int); int (*fileattr_set)(struct user_namespace *mnt_userns,