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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EED6BC38142 for ; Tue, 23 Aug 2022 17:07:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343751AbiHWRHK (ORCPT ); Tue, 23 Aug 2022 13:07:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36450 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343929AbiHWREE (ORCPT ); Tue, 23 Aug 2022 13:04:04 -0400 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AFF75150156 for ; Tue, 23 Aug 2022 06:33:40 -0700 (PDT) Received: by mail-pf1-x42e.google.com with SMTP id x19so10704237pfq.1 for ; Tue, 23 Aug 2022 06:33:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=aCSXGk9NtNmglUVpbUQ1Rjs+YdBMM2XU3YePZpV6vnQ=; b=jLH60+HfG5U8ezVkTAuijLoLylLR3TAnYTCNGkRSYaXVEB1RrgRj4cZ2E0d22eIC3K 92/vTy/0T5iBMTrT7lsqB+KGysInPkNuKKnjHNVnN6+Fb/H7y0iRIdwHNfeeLz3Xl+rr vbJXmwYdB4hKN2MM558O7p4hjglh6k8FUBX/IvfdET1tE2p8/7Gjk6uk8p50aldySkK6 VKuhRIy4g+j6vcnnlPJekfl3u4zL2Ns0QVwlcmhJ/YILoBFCBwIF26bshgM72tRqOIqE hxUvNXESs3HU0UWTjccyx+qgYb6k8iV9J0k3MTBakGTgT2uM7UT35Jqrf6wxOv/WeqLV IZYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=aCSXGk9NtNmglUVpbUQ1Rjs+YdBMM2XU3YePZpV6vnQ=; b=wxAM3YZqLyOEJ6u92j+g8mIL+4LkgXvLfuJ347cHKJ/Pn254hjrHi1E5hBTpdRA7XM z5nf+03mvhRVt22lrFhKfyqbbJc7axNH6HMmbS+0OhAMErcdTKmpTrE/Yxhd+aL7Mg9h eeBCJJ4VQk2GW1lcFBxmyUyZ/TCTmaENWTgR4v1yHPRxPIXg5oETxpCRSzS0/ZqkK/Ps ewZmznOBDi2q/c8iu0LCYbYhrGe6AbDLYCzmJxgUkM/oHirJ8gZk1XUFbhVTdItUjpDL /xyekq9bDvBtcgo+lPyuwUxpwPkjpONx+4W57l6hTVur8CnEDaTt25OP0/QbL6yN7Hah eOdg== X-Gm-Message-State: ACgBeo3bcqS7Rqen5JmuPAn7wyO6vUv8wSg8xNHhPNK2RDDxkR0Fx2pJ hbMhgu913c/syiimw8IXNb0yTw== X-Google-Smtp-Source: AA6agR6S6rfRj/zc3mfjlga4zrGt9A0T25FwyEPhGMSVV9ZoGj3YuGzKeEzbZSewB8Y4MIpq+O8cqA== X-Received: by 2002:a63:b07:0:b0:429:411a:ff51 with SMTP id 7-20020a630b07000000b00429411aff51mr20162901pgl.207.1661261620081; Tue, 23 Aug 2022 06:33:40 -0700 (PDT) Received: from [192.168.1.136] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id ei23-20020a17090ae55700b001f7a76d6f28sm9963727pjb.18.2022.08.23.06.33.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Aug 2022 06:33:39 -0700 (PDT) Message-ID: Date: Tue, 23 Aug 2022 07:33:38 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.1.2 Subject: Re: [PATCH 3/3] /dev/null: add IORING_OP_URING_CMD support Content-Language: en-US To: Greg Kroah-Hartman , Paul Moore Cc: linux-security-module@vger.kernel.org, selinux@vger.kernel.org, io-uring@vger.kernel.org, Arnd Bergmann , Luis Chamberlain References: <166120321387.369593.7400426327771894334.stgit@olly> <166120327984.369593.8371751426301540450.stgit@olly> From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: On 8/23/22 12:51 AM, Greg Kroah-Hartman wrote: > On Mon, Aug 22, 2022 at 05:21:19PM -0400, Paul Moore wrote: >> This patch adds support for the io_uring command pass through, aka >> IORING_OP_URING_CMD, to the /dev/null driver. As with all of the >> /dev/null functionality, the implementation is just a simple sink >> where commands go to die, but it should be useful for developers who >> need a simple IORING_OP_URING_CMD test device that doesn't require >> any special hardware. >> >> Cc: Arnd Bergmann >> Cc: Greg Kroah-Hartman >> Signed-off-by: Paul Moore >> --- >> drivers/char/mem.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/drivers/char/mem.c b/drivers/char/mem.c >> index 84ca98ed1dad..32a932a065a6 100644 >> --- a/drivers/char/mem.c >> +++ b/drivers/char/mem.c >> @@ -480,6 +480,11 @@ static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, >> return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); >> } >> >> +static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags) >> +{ >> + return 0; > > If a callback just returns 0, that implies it is not needed at all and > can be removed and then you are back at the original file before your > commit :) In theory you are correct, but the empty hook is needed so that submitting an io_uring cmd to the file type is attempted. If not it's just errored upfront. Paul, is it strictly needed to test the selinux uring cmd policy? If the operation would've been attempted but null doesn't support it, you'd get -1/EOPNOTSUPP - and supposedly you'd get EACCES/EPERM or something if it's filtered? -- Jens Axboe