From patchwork Wed Sep 28 16:08:22 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12992482 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 013A5C04A95 for ; Wed, 28 Sep 2022 16:13:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234192AbiI1QNZ (ORCPT ); Wed, 28 Sep 2022 12:13:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234532AbiI1QNR (ORCPT ); Wed, 28 Sep 2022 12:13:17 -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 4FC0FB24AD; Wed, 28 Sep 2022 09:13:12 -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 8FBA161F22; Wed, 28 Sep 2022 16:13:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 896DEC43470; Wed, 28 Sep 2022 16:13:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664381591; bh=c1QIwhRZNd/jfB4EhdC3FTlJLDrSM4ar3Pa6BBxWBz0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cHmiVf0BUUckU/BKUtlCGv8sMLpugXhSmcQfTSrkA3QBq9PGHnn7vbHj5SCYojZtY KcQDOC1s7IdCo1apdWYX5XLZYj4gZCA3T7CGwFf7rhDCEs9dTdlm8MTj/U2XUFVmig mFBFh0tZvV8JuIjvXxi48ihFEgg5fbwd531tqF1vRalW1FKrbsyemkuP3G0fpoKEVj 7VmKjqCDblijMM6jjeVk00YGyf5C8aPK/ql3voLTIU92zYv/IGPIeko/uwEsqKqb/P ooXlBbhEpjEi++OvmR6HOJQbiAsrTv8Y80PaRxynYOhBXT/Mcphzu9gauiwYRgcyLX otB/nfZ/RyslQ== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Christian Brauner , Seth Forshee , Christoph Hellwig , Al Viro , Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , Christian Schoenebeck , v9fs-developer@lists.sourceforge.net, linux-security-module@vger.kernel.org Subject: [PATCH v3 08/29] 9p: implement set acl method Date: Wed, 28 Sep 2022 18:08:22 +0200 Message-Id: <20220928160843.382601-9-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220928160843.382601-1-brauner@kernel.org> References: <20220928160843.382601-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6400; i=brauner@kernel.org; h=from:subject; bh=c1QIwhRZNd/jfB4EhdC3FTlJLDrSM4ar3Pa6BBxWBz0=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSSbFFZXXfc5s+Q9z1Lts5c+z9wuXcl8ISbvi/f6RafFM+ef n7G2qqOUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAizG6MDLN06lxfWazZFGR2mO/ozL qz5kaat/9aCoYW55QcT2LvU2BkuNW6ydsznPfr3LZ56xxuzHvyZoPmLWn+V8d+mDbZrHO9zgMA 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]. In order to build a type safe posix api around get and set acl we need all filesystem to implement get and set acl. So far 9p implemented a ->get_inode_acl() operation that didn't require access to the dentry in order to allow (limited) permission checking via posix acls in the vfs. Now that we have get and set acl inode operations that take a dentry argument we can give 9p get and set acl inode operations. This is mostly a light refactoring of the codepaths currently used in 9p posix acl xattr handler. After we have fully implemented the posix acl api and switched the vfs over to it, the 9p specific posix acl xattr handler and associated code will be removed. Note, until the vfs has been switched to the new posix acl api this patch is a non-functional change. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Signed-off-by: Christian Brauner (Microsoft) --- Notes: /* v2 */ Al Viro : - Fix leak due to early return instead of goto. Christian Brauner (Microsoft) : - Fix leak and call kfree() when we skip setting posix acls because acl can be represented by mode bits. /* v3 */ unchanged fs/9p/acl.c | 94 ++++++++++++++++++++++++++++++++++++++++++ fs/9p/acl.h | 3 ++ fs/9p/vfs_inode_dotl.c | 2 + 3 files changed, 99 insertions(+) diff --git a/fs/9p/acl.c b/fs/9p/acl.c index 67f8b57c67e0..135b26cee63a 100644 --- a/fs/9p/acl.c +++ b/fs/9p/acl.c @@ -151,6 +151,100 @@ struct posix_acl *v9fs_iop_get_acl(struct user_namespace *mnt_userns, return v9fs_get_cached_acl(d_inode(dentry), type); } +int v9fs_iop_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, + struct posix_acl *acl, int type) +{ + int retval; + size_t size = 0; + void *value = NULL; + const char *acl_name; + struct v9fs_session_info *v9ses; + struct inode *inode = d_inode(dentry); + + if (acl) { + retval = posix_acl_valid(inode->i_sb->s_user_ns, acl); + if (retval) + goto err_out; + + size = posix_acl_xattr_size(acl->a_count); + + value = kzalloc(size, GFP_NOFS); + if (!value) { + retval = -ENOMEM; + goto err_out; + } + + retval = posix_acl_to_xattr(&init_user_ns, acl, value, size); + if (retval < 0) + goto err_out; + } + + /* + * set the attribute on the remote. Without even looking at the + * xattr value. We leave it to the server to validate + */ + acl_name = posix_acl_xattr_name(type); + v9ses = v9fs_dentry2v9ses(dentry); + if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) { + retval = v9fs_xattr_set(dentry, acl_name, value, size, 0); + goto err_out; + } + + if (S_ISLNK(inode->i_mode)) { + retval = -EOPNOTSUPP; + goto err_out; + } + + if (!inode_owner_or_capable(&init_user_ns, inode)) { + retval = -EPERM; + goto err_out; + } + + switch (type) { + case ACL_TYPE_ACCESS: + if (acl) { + struct iattr iattr = {}; + struct posix_acl *acl_mode = acl; + + retval = posix_acl_update_mode(&init_user_ns, inode, + &iattr.ia_mode, + &acl_mode); + if (retval) + goto err_out; + if (!acl_mode) { + /* + * ACL can be represented by the mode bits. + * So don't update ACL below. + */ + kfree(value); + value = NULL; + size = 0; + } + iattr.ia_valid = ATTR_MODE; + /* + * FIXME should we update ctime ? + * What is the following setxattr update the mode ? + */ + v9fs_vfs_setattr_dotl(&init_user_ns, dentry, &iattr); + } + break; + case ACL_TYPE_DEFAULT: + if (!S_ISDIR(inode->i_mode)) { + retval = acl ? -EINVAL : 0; + goto err_out; + } + break; + } + + retval = v9fs_xattr_set(dentry, acl_name, value, size, 0); + if (!retval) + set_cached_acl(inode, type, acl); + +err_out: + kfree(value); + return retval; +} + static int v9fs_set_acl(struct p9_fid *fid, int type, struct posix_acl *acl) { int retval; diff --git a/fs/9p/acl.h b/fs/9p/acl.h index 359dab4da900..4c60a2bce5de 100644 --- a/fs/9p/acl.h +++ b/fs/9p/acl.h @@ -12,6 +12,8 @@ struct posix_acl *v9fs_iop_get_inode_acl(struct inode *inode, int type, bool rcu); struct posix_acl *v9fs_iop_get_acl(struct user_namespace *mnt_userns, struct dentry *dentry, int type); +int v9fs_iop_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, + struct posix_acl *acl, int type); int v9fs_acl_chmod(struct inode *inode, struct p9_fid *fid); int v9fs_set_create_acl(struct inode *inode, struct p9_fid *fid, struct posix_acl *dacl, struct posix_acl *acl); @@ -21,6 +23,7 @@ void v9fs_put_acl(struct posix_acl *dacl, struct posix_acl *acl); #else #define v9fs_iop_get_inode_acl NULL #define v9fs_iop_get_acl NULL +#define v9fs_iop_set_acl NULL static inline int v9fs_get_acl(struct inode *inode, struct p9_fid *fid) { return 0; diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c index a4211fcb9168..03c1743c4aff 100644 --- a/fs/9p/vfs_inode_dotl.c +++ b/fs/9p/vfs_inode_dotl.c @@ -985,6 +985,7 @@ const struct inode_operations v9fs_dir_inode_operations_dotl = { .listxattr = v9fs_listxattr, .get_inode_acl = v9fs_iop_get_inode_acl, .get_acl = v9fs_iop_get_acl, + .set_acl = v9fs_iop_set_acl, }; const struct inode_operations v9fs_file_inode_operations_dotl = { @@ -993,6 +994,7 @@ const struct inode_operations v9fs_file_inode_operations_dotl = { .listxattr = v9fs_listxattr, .get_inode_acl = v9fs_iop_get_inode_acl, .get_acl = v9fs_iop_get_acl, + .set_acl = v9fs_iop_set_acl, }; const struct inode_operations v9fs_symlink_inode_operations_dotl = {