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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E69A9C4167B for ; Tue, 5 Dec 2023 04:14:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wCXWaTK2cT20XJ2gH5tKnNoHz1rvmd5jnRMvdwguqmM=; b=PxsY4TYND6rC6QCfOXHN1hDQXK tjuNMemxpvGhtXiDnk5bLvKadc0irf7wZ5hI7SRCytCdslj9ZgugWi8mIwnPkvzv6AbMEwAAOjJWC xOLoFC/G5/ZkCGcowJc0H1HrLqIFK+pRoN2jxVig0c0UZ4ElMB9IkFZSjWJBcLEtNeE2gCW8KLCEM v9mgyxMWwi5vQ6weBX63/2GKPlbelX0BzfC0Vb6ue3hBIGbnv+g/qKiJvGIEjzf17rQN8NmNbNmzV alR9El+Xpj00UQznnOCFwMs/nK2tk4m/GXJHfQjEAHUcmRN6TrN1HkSCjJWzi/OT7seEjDCz/ZaF+ M2E8+kMw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rAMpY-006CSP-34; Tue, 05 Dec 2023 04:14:45 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rAMpW-006CRr-0L for linux-nvme@lists.infradead.org; Tue, 05 Dec 2023 04:14:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701749677; 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: in-reply-to:in-reply-to:references:references; bh=wCXWaTK2cT20XJ2gH5tKnNoHz1rvmd5jnRMvdwguqmM=; b=g5NTyIbkCmRfGKTZAb6jboDO85HY0LiF3H/ay9JQX0b7erAAUCCpqRaAREFBud30bE57r3 CMguK2AI6Nnd6ASER4YGKWvEilGOenetAJlf5uRZfZJUX/2dyHFbKT7RhSJHqYkcSDscym 2l01mLiuS2/2J9Qd9d2m0BD1sdlCaCk= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-86-TNjQEJEQNHGBd5ntzJrjVA-1; Mon, 04 Dec 2023 23:14:33 -0500 X-MC-Unique: TNjQEJEQNHGBd5ntzJrjVA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E15F73C0BE2E; Tue, 5 Dec 2023 04:14:32 +0000 (UTC) Received: from fedora (unknown [10.72.120.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2104C2166B27; Tue, 5 Dec 2023 04:14:26 +0000 (UTC) Date: Tue, 5 Dec 2023 12:14:22 +0800 From: Ming Lei To: Keith Busch Cc: Jeff Moyer , Keith Busch , linux-nvme@lists.infradead.org, io-uring@vger.kernel.org, axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, asml.silence@gmail.com, linux-security-module@vger.kernel.org, Kanchan Joshi Subject: Re: [PATCH 1/2] iouring: one capable call per iouring instance Message-ID: References: <20231204175342.3418422-1-kbusch@meta.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231204_201442_241221_AD787096 X-CRM114-Status: GOOD ( 19.25 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Dec 04, 2023 at 11:57:55AM -0700, Keith Busch wrote: > On Mon, Dec 04, 2023 at 01:40:58PM -0500, Jeff Moyer wrote: > > I added a CC: linux-security-module@vger > > Keith Busch writes: > > > From: Keith Busch > > > > > > The uring_cmd operation is often used for privileged actions, so drivers > > > subscribing to this interface check capable() for each command. The > > > capable() function is not fast path friendly for many kernel configs, > > > and this can really harm performance. Stash the capable sys admin > > > attribute in the io_uring context and set a new issue_flag for the > > > uring_cmd interface. > > > > I have a few questions. What privileged actions are performance > > sensitive? I would hope that anything requiring privileges would not > > be in a fast path (but clearly that's not the case). > > Protocol specifics that don't have a generic equivalent. For example, > NVMe FDP is reachable only through the uring_cmd and ioctl interfaces, > but you use it like normal reads and writes so has to be as fast as the > generic interfaces. But normal read/write pt command doesn't require ADMIN any more since commit 855b7717f44b ("nvme: fine-granular CAP_SYS_ADMIN for nvme io commands"), why do you have to pay the cost of checking capable(CAP_SYS_ADMIN)? Thanks, Ming