From patchwork Wed Apr 27 19:12:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 12829386 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 DA7B9C433EF for ; Wed, 27 Apr 2022 19:16:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233719AbiD0TTW (ORCPT ); Wed, 27 Apr 2022 15:19:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232853AbiD0TTN (ORCPT ); Wed, 27 Apr 2022 15:19:13 -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 27BF028E10 for ; Wed, 27 Apr 2022 12:13:25 -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 B4EB061A00 for ; Wed, 27 Apr 2022 19:13:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 972B1C385A7; Wed, 27 Apr 2022 19:13:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651086804; bh=AL8GiMWUOKq04yGI7r7aMJqU4jt3Jz8zt+t2KqAdU5U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UV6Qs3W/IwOVQRUzzgky5s8pQYYLT/oHqmhuPyMmq3t4DijC1u+Sa4+dJA0/MZ67h Re/i9puf9f254Hn5OgzOPWs0LRvoixao5bl0yIuSPtXZqCSS2ZGpxqrngP96asm/X7 pJ4cvgup2z2S1pvubzXpxt8rdw4J5zhVyt7XAf7zMe5o+Bf/B2lYSTdswJnMedIZ3b eS4OPsJU0RvaEb81jSyQH0GtFlZPnT1KBqYTWsHTqOA0lsONaoAoSWIlMQx4HtW1Ga E+9HcyYi3fspLzRWEYYfrQCWslufKuJaXogNxMJIJ2OfXh+lTpK8ZXeWZXuQZKAsKp LHNzFx15mS6zg== From: Jeff Layton To: ceph-devel@vger.kernel.org Cc: xiubli@redhat.com, lhenriques@suse.de, idryomov@gmail.com, Eric Biggers Subject: [PATCH v14 10/64] fscrypt: add fscrypt_context_for_new_inode Date: Wed, 27 Apr 2022 15:12:20 -0400 Message-Id: <20220427191314.222867-11-jlayton@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220427191314.222867-1-jlayton@kernel.org> References: <20220427191314.222867-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Most filesystems just call fscrypt_set_context on new inodes, which usually causes a setxattr. That's a bit late for ceph, which can send along a full set of attributes with the create request. Doing so allows it to avoid race windows that where the new inode could be seen by other clients without the crypto context attached. It also avoids the separate round trip to the server. Refactor the fscrypt code a bit to allow us to create a new crypto context, attach it to the inode, and write it to the buffer, but without calling set_context on it. ceph can later use this to marshal the context into the attributes we send along with the create request. Acked-by: Eric Biggers Signed-off-by: Jeff Layton --- fs/crypto/policy.c | 35 +++++++++++++++++++++++++++++------ include/linux/fscrypt.h | 1 + 2 files changed, 30 insertions(+), 6 deletions(-) diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index ed3d623724cd..ec861af96252 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -664,6 +664,32 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir) return fscrypt_get_dummy_policy(dir->i_sb); } +/** + * fscrypt_context_for_new_inode() - create an encryption context for a new inode + * @ctx: where context should be written + * @inode: inode from which to fetch policy and nonce + * + * Given an in-core "prepared" (via fscrypt_prepare_new_inode) inode, + * generate a new context and write it to ctx. ctx _must_ be at least + * FSCRYPT_SET_CONTEXT_MAX_SIZE bytes. + * + * Return: size of the resulting context or a negative error code. + */ +int fscrypt_context_for_new_inode(void *ctx, struct inode *inode) +{ + struct fscrypt_info *ci = inode->i_crypt_info; + + BUILD_BUG_ON(sizeof(union fscrypt_context) != + FSCRYPT_SET_CONTEXT_MAX_SIZE); + + /* fscrypt_prepare_new_inode() should have set up the key already. */ + if (WARN_ON_ONCE(!ci)) + return -ENOKEY; + + return fscrypt_new_context(ctx, &ci->ci_policy, ci->ci_nonce); +} +EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode); + /** * fscrypt_set_context() - Set the fscrypt context of a new inode * @inode: a new inode @@ -680,12 +706,9 @@ int fscrypt_set_context(struct inode *inode, void *fs_data) union fscrypt_context ctx; int ctxsize; - /* fscrypt_prepare_new_inode() should have set up the key already. */ - if (WARN_ON_ONCE(!ci)) - return -ENOKEY; - - BUILD_BUG_ON(sizeof(ctx) != FSCRYPT_SET_CONTEXT_MAX_SIZE); - ctxsize = fscrypt_new_context(&ctx, &ci->ci_policy, ci->ci_nonce); + ctxsize = fscrypt_context_for_new_inode(&ctx, inode); + if (ctxsize < 0) + return ctxsize; /* * This may be the first time the inode number is available, so do any diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index c79c4333f769..2b892376d325 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -273,6 +273,7 @@ int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg); int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg); int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg); int fscrypt_has_permitted_context(struct inode *parent, struct inode *child); +int fscrypt_context_for_new_inode(void *ctx, struct inode *inode); int fscrypt_set_context(struct inode *inode, void *fs_data); struct fscrypt_dummy_policy {