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=-5.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 4E89DC433DF for ; Wed, 13 May 2020 18:53:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F265F2065C for ; Wed, 13 May 2020 18:53:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="IbEVDf1P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390325AbgEMSxd (ORCPT ); Wed, 13 May 2020 14:53:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S2387516AbgEMSxc (ORCPT ); Wed, 13 May 2020 14:53:32 -0400 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45BA9C061A0F for ; Wed, 13 May 2020 11:53:32 -0700 (PDT) Received: by mail-wr1-x442.google.com with SMTP id h17so744785wrc.8 for ; Wed, 13 May 2020 11:53:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=pXu37DD6iE65dDGCF4WvK7cyvgiimEWOvvgpryvd52U=; b=IbEVDf1PZkcsC9qKSfRpq/TZXfimI98pReSCcaQgTPNl9HmndoODpa4MDeOulOvRz4 yCi4Y0M//sK1fidl4u5Podrn0hGfzM9JzccG27h3Bum61GNrk5w9Z1sOClL7Gns6+5GF NnqDrlIux2oiU+oQESCrAfiMljk+vnBzT/ypM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=pXu37DD6iE65dDGCF4WvK7cyvgiimEWOvvgpryvd52U=; b=brvl9EsR5ATQXRlwWEtClj+2881SBAidLn+mMZ5wlQydFjckfmNUHz2f+KHD602nBv s/T2Xa7kuc41/sxxVJhqbkcMPb/mJEA9e9mH23WX5v6LcSOTRDM9e5vOdbc5aaxfpjUZ DaCM1q4Rs03TM67LWobhvdY3AZKCSPJw7UgvBiojgwIk0ynseyua0gxdIsZFy7QzXIl7 f0l8B87M5Th26NuNjMa1SJTbNxcgAS2Ze74mbSIXVKEUlaDw9ZnoNKK0IS4Hi2JLppuD WSWYHsuJJk13/1wIubR1W4lClIWbasjQBc69b3v67SF9ch/QhXZ1Ojpt14nRovqghPSz b74g== X-Gm-Message-State: AOAM532jUAd5fcHbIHyZYkZVPUV5JkesCLxHUBv2/ug4wMs6XQhy6BcW atHVgHVpMGMFs1haahk7BrR65Q== X-Google-Smtp-Source: ABdhPJyQTNm1BSKNK4nPH8PwhT168mr3Et0SlCcd67hBnuW+VdEO/ieVYFVuvkPPR1fp/Uk3isIZEg== X-Received: by 2002:adf:a151:: with SMTP id r17mr761655wrr.161.1589396010916; Wed, 13 May 2020 11:53:30 -0700 (PDT) Received: from [10.136.13.65] ([192.19.228.250]) by smtp.gmail.com with ESMTPSA id i17sm37309331wml.23.2020.05.13.11.53.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 May 2020 11:53:30 -0700 (PDT) Subject: Re: [PATCH v5 1/7] fs: introduce kernel_pread_file* support To: Mimi Zohar , Luis Chamberlain , Greg Kroah-Hartman , David Brown , Alexander Viro , Shuah Khan , bjorn.andersson@linaro.org, Shuah Khan , Arnd Bergmann Cc: "Rafael J . Wysocki" , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-fsdevel@vger.kernel.org, BCM Kernel Feedback , Olof Johansson , Andrew Morton , Dan Carpenter , Colin Ian King , Kees Cook , Takashi Iwai , linux-kselftest@vger.kernel.org, Andy Gross , linux-security-module , linux-integrity References: <20200508002739.19360-1-scott.branden@broadcom.com> <20200508002739.19360-2-scott.branden@broadcom.com> <1589395153.5098.158.camel@kernel.org> From: Scott Branden Message-ID: <0e6b5f65-8c61-b02e-7d35-b4ae52aebcf3@broadcom.com> Date: Wed, 13 May 2020 11:53:23 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <1589395153.5098.158.camel@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi Mimi, On 2020-05-13 11:39 a.m., Mimi Zohar wrote: > [Cc'ing linux-security-module, linux-integrity] > > On Thu, 2020-05-07 at 17:27 -0700, Scott Branden wrote: >> Add kernel_pread_file* support to kernel to allow for partial read >> of files with an offset into the file. Existing kernel_read_file >> functions call new kernel_pread_file functions with offset=0 and >> flags=KERNEL_PREAD_FLAG_WHOLE. >> >> Signed-off-by: Scott Branden >> --- > > >> @@ -941,14 +955,16 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size, The checkpatch shows this as kernel_read_file when it is actually the new function kernel_pread_file. Please see the call to kernel_pread_file from kernel_read_file in the complete patch rather this snippet. >> >> if (bytes == 0) >> break; >> + >> + buf_pos += bytes; >> } >> >> - if (pos != i_size) { >> + if (pos != read_end) { >> ret = -EIO; >> goto out_free; >> } >> >> - ret = security_kernel_post_read_file(file, *buf, i_size, id); >> + ret = security_kernel_post_read_file(file, *buf, alloc_size, id); >> if (!ret) >> *size = pos; > Prior to the patch set that introduced this security hook, firmware > would be read twice, once for measuring/appraising the firmware and > again reading the file contents into memory.  Partial reads will break > both IMA's measuring the file and appraising the file signatures. The partial file read support is needed for request_firmware_into_buf from drivers.  The EXPORT_SYMBOL_GPL is being removed so that there can be no abuse of the partial file read support.  Such file integrity checks are not needed for this use case.  The partial file (firmware image) is actually downloaded in portions and verified on the device it is loaded to. Regards,  Scott