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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F04A2C4CECE for ; Fri, 13 Mar 2020 13:29:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C954F20746 for ; Fri, 13 Mar 2020 13:29:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ExgfqPLC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726837AbgCMN34 (ORCPT ); Fri, 13 Mar 2020 09:29:56 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:45481 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726832AbgCMN34 (ORCPT ); Fri, 13 Mar 2020 09:29:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584106195; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3+ksI+XSY2k8kxQCweElbOHXEbbN3FX9hGarbW0qLpE=; b=ExgfqPLCHFei3/BGbAitRC+ZfLQxDc1vIdgQBJY6bAad7v6hYR/0mT+vh8SRdM8MorYZNg R05HXuGLNEhhc+1Li+bjuy5DHpiLStrE2BYt2KlqC/szqE9Ts6/9FPTZrigTq2ImZNjFs2 yyTo3bXmoIbBXwWLrXP3lG5GYjEqROI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-285-SOYfMbpkNq6cmHdbDSn14g-1; Fri, 13 Mar 2020 09:29:52 -0400 X-MC-Unique: SOYfMbpkNq6cmHdbDSn14g-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D4302189F762; Fri, 13 Mar 2020 13:29:49 +0000 (UTC) Received: from llong.remote.csb (ovpn-125-21.rdu2.redhat.com [10.10.125.21]) by smtp.corp.redhat.com (Postfix) with ESMTP id E14A660CC0; Fri, 13 Mar 2020 13:29:47 +0000 (UTC) Subject: Re: [PATCH v2 1/2] KEYS: Don't write out to userspace while holding key semaphore To: Jarkko Sakkinen Cc: David Howells , James Morris , "Serge E. Hallyn" , Mimi Zohar , keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, Sumit Garg , Jerry Snitselaar , Roberto Sassu , Eric Biggers , Chris von Recklinghausen References: <20200308170410.14166-1-longman@redhat.com> <20200308170410.14166-2-longman@redhat.com> <20200313010425.GA11360@linux.intel.com> From: Waiman Long Organization: Red Hat Message-ID: Date: Fri, 13 Mar 2020 09:29:47 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20200313010425.GA11360@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On 3/12/20 9:04 PM, Jarkko Sakkinen wrote: > On Sun, Mar 08, 2020 at 01:04:09PM -0400, Waiman Long wrote: >> + /* >> + * Read methods will just return the required length >> + * without any copying if the provided length isn't big >> + * enough. >> + */ >> + if ((ret > 0) && (ret <= buflen) && buffer && >> + copy_to_user(buffer, tmpbuf, ret)) >> + ret = -EFAULT; > Please, reorg and remove redundant parentheses: > > /* > * Read methods will just return the required length > * without any copying if the provided length isn't big > * enough. > */ > if (ret > 0 && ret <= buflen) { > if (buffer && copy_to_user(buffer, tmpbuf, ret)) > ret = -EFAULT; > } > > Now the comment is attached to the exact right thing. The previous > organization is a pain to look at when backtracking commits for > whatever reason in the future. Yes, I can reorganize the code. > I'm also wondering, would it be possible to rework the code in a way > that you don't have check whether buffer is valid on a constant basis? One way to do that is to extract the down_read/up_read block into a helper function and then have 2 separate paths - one for length retrieval and another one for reading the key. I think that will make the code a bit easier easier to read. Thanks, Longman