From patchwork Thu Sep 29 15:30:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12994278 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 829D1C43217 for ; Thu, 29 Sep 2022 15:33:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235899AbiI2PdE (ORCPT ); Thu, 29 Sep 2022 11:33:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235924AbiI2PcN (ORCPT ); Thu, 29 Sep 2022 11:32:13 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1596E130BE1; Thu, 29 Sep 2022 08:31:34 -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 A0BF461484; Thu, 29 Sep 2022 15:31:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 101FFC433D7; Thu, 29 Sep 2022 15:31:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664465493; bh=ZZT+Vg8ZsA7Z3GsTwgF1uh9F8lsQaxUMZKUhdw3BKSU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TTGiN8lwQxCAwh+wERPddzdTGt/6Pa13CpJ8Qjvk37O3Pbg/CMYKdwW6T7KF7i8kZ paL8cFcPwq6k8TFYhyb/allIWZRvgl54VnHzn3yHeVI7k5RaQ6h9v6K9EaxUHDDonK IBVU0ZgaMjrIGQz0qg/9xIEJljdYU2C0T5BiTasea5CrRzziAM50zWf+dIDy/mSJQc 0nH6T+UI2qpwL1/Qb+VCLN1+q5K9CFQLFeM6rkEE7lGwvAnFBf5HfkrOqMBk1/sav+ v/h0obXcXJWiACZsKTyPYIlvbtdqS0ksa/vM510ivkTy1WpmuBUDrfKp9aKIwHy4Z0 4jXIG5edvAiRQ== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Christian Brauner , Seth Forshee , Christoph Hellwig , Al Viro , Mimi Zohar , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v4 15/30] acl: add vfs_set_acl() Date: Thu, 29 Sep 2022 17:30:25 +0200 Message-Id: <20220929153041.500115-16-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220929153041.500115-1-brauner@kernel.org> References: <20220929153041.500115-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6007; i=brauner@kernel.org; h=from:subject; bh=ZZT+Vg8ZsA7Z3GsTwgF1uh9F8lsQaxUMZKUhdw3BKSU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSSb7hK5Fc+xcL/az4zv3EZmS2VbNvSa79/2Y9bdSvuaD7UG f+SVOkpZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACZydwrDP9Nbos8n/s68q6zg1jmV1b spLjpZbdOJWS49DowPQ91KmRgZprIxzf3CF134f91DxpyG4BPxDdfn/37KHrWRKUeX98AKdgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org 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_set_acl() api that can be used to set 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 /* v3 */ unchanged /* v4 */ Christoph Hellwig : - s/EXPORT_SYMBOL/EXPORT_SYMBOL_GPL/ - return -EOPNOTSUPP from vfs_set_acl() if !CONFIG_FS_POSIX_ACL Christian Brauner (Microsoft) : - use newly introduced may_write_xattr() helper fs/posix_acl.c | 117 ++++++++++++++++++++++++++++++++++++++ include/linux/posix_acl.h | 10 ++++ 2 files changed, 127 insertions(+) diff --git a/fs/posix_acl.c b/fs/posix_acl.c index 3749d07881cc..c920fb98e29b 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -24,6 +24,11 @@ #include #include #include +#include +#include +#include + +#include "internal.h" static struct posix_acl **acl_by_type(struct inode *inode, int type) { @@ -1254,3 +1259,115 @@ int simple_acl_create(struct inode *dir, struct inode *inode) posix_acl_release(acl); return 0; } + +static inline int posix_acl_type(const char *name) +{ + if (strcmp(name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) + return ACL_TYPE_ACCESS; + else if (strcmp(name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0) + return ACL_TYPE_DEFAULT; + + return -1; +} + +static int vfs_set_acl_idmapped_mnt(struct user_namespace *mnt_userns, + struct user_namespace *fs_userns, + struct posix_acl *acl) +{ + for (int n = 0; n < acl->a_count; n++) { + struct posix_acl_entry *acl_e = &acl->a_entries[n]; + + switch (acl_e->e_tag) { + case ACL_USER: + acl_e->e_uid = from_vfsuid(mnt_userns, fs_userns, + VFSUIDT_INIT(acl_e->e_uid)); + break; + case ACL_GROUP: + acl_e->e_gid = from_vfsgid(mnt_userns, fs_userns, + VFSGIDT_INIT(acl_e->e_gid)); + break; + } + } + + return 0; +} + +/** + * vfs_set_acl - set posix acls + * @mnt_userns: user namespace of the mount + * @dentry: the dentry based on which to set the posix acls + * @acl_name: the name of the posix acl + * @kacl: the posix acls in the appropriate VFS format + * + * This function sets @kacl. The caller must all posix_acl_release() on @kacl + * afterwards. + * + * Return: On success 0, on error negative errno. + */ +int vfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, + const char *acl_name, struct posix_acl *kacl) +{ + int acl_type; + int error; + struct inode *inode = d_inode(dentry); + struct inode *delegated_inode = NULL; + + acl_type = posix_acl_type(acl_name); + if (acl_type < 0) + return -EINVAL; + + if (kacl) { + /* + * If we're on an idmapped mount translate from mount specific + * vfs{g,u}id_t into global filesystem k{g,u}id_t. + * Afterwards we can cache the POSIX ACLs filesystem wide and - + * if this is a filesystem with a backing store - ultimately + * translate them to backing store values. + */ + error = vfs_set_acl_idmapped_mnt(mnt_userns, i_user_ns(inode), kacl); + if (error) + return error; + } + +retry_deleg: + inode_lock(inode); + + /* + * We only care about restrictions the inode struct itself places upon + * us otherwise POSIX ACLs aren't subject to any VFS restrictions. + */ + error = may_write_xattr(mnt_userns, inode); + if (error) + goto out_inode_unlock; + + error = security_inode_set_acl(mnt_userns, dentry, acl_name, kacl); + if (error) + goto out_inode_unlock; + + error = try_break_deleg(inode, &delegated_inode); + if (error) + goto out_inode_unlock; + + if (inode->i_opflags & IOP_XATTR) + error = set_posix_acl(mnt_userns, dentry, acl_type, kacl); + else if (unlikely(is_bad_inode(inode))) + error = -EIO; + else + error = -EOPNOTSUPP; + if (!error) { + fsnotify_xattr(dentry); + evm_inode_post_set_acl(dentry, acl_name, kacl); + } + +out_inode_unlock: + inode_unlock(inode); + + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + + return error; +} +EXPORT_SYMBOL_GPL(vfs_set_acl); diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h index 07e171b4428a..316b05c1dc97 100644 --- a/include/linux/posix_acl.h +++ b/include/linux/posix_acl.h @@ -99,6 +99,9 @@ static inline void cache_no_acl(struct inode *inode) inode->i_acl = NULL; inode->i_default_acl = NULL; } + +int vfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, + const char *acl_name, struct posix_acl *kacl); #else static inline int posix_acl_chmod(struct user_namespace *mnt_userns, struct dentry *dentry, umode_t mode) @@ -126,6 +129,13 @@ static inline int posix_acl_create(struct inode *inode, umode_t *mode, static inline void forget_all_cached_acls(struct inode *inode) { } + +static inline int vfs_set_acl(struct user_namespace *mnt_userns, + struct dentry *dentry, const char *name, + struct posix_acl *acl) +{ + return -EOPNOTSUPP; +} #endif /* CONFIG_FS_POSIX_ACL */ struct posix_acl *get_inode_acl(struct inode *inode, int type);