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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9695C433F5 for ; Tue, 12 Oct 2021 08:46:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8126161056 for ; Tue, 12 Oct 2021 08:46:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235122AbhJLIsT (ORCPT ); Tue, 12 Oct 2021 04:48:19 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:55577 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234952AbhJLIsQ (ORCPT ); Tue, 12 Oct 2021 04:48:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634028374; 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=8jbtmrvdydVcbKtmwH0mVqKY5lC9q0zSEeq9Jm8aa9s=; b=CQGeS03gG8WfLs2sYm1FN/PySQTz4FweB34zFGMDzmkdoOS2AVmOtWRatdmoHTCKtlgQDz 3kHcGp6Q+F4XrAKDzQoyGU1fp9bN7bN6H12fpncsYzVI7d+dnkqzleEiYcaQHCO2n3VIMo tv+PKJdKos46+p2Hza3w9DtrtpmVWGA= Received: from mail-lf1-f72.google.com (mail-lf1-f72.google.com [209.85.167.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-340-slt68gxEMdGz-KqGsffoIw-1; Tue, 12 Oct 2021 04:46:13 -0400 X-MC-Unique: slt68gxEMdGz-KqGsffoIw-1 Received: by mail-lf1-f72.google.com with SMTP id br42-20020a056512402a00b003fd94a74905so3103568lfb.7 for ; Tue, 12 Oct 2021 01:46:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=8jbtmrvdydVcbKtmwH0mVqKY5lC9q0zSEeq9Jm8aa9s=; b=n/eBp6zbRl31Nowd896vx9wH8pVuTJUrHPk9M9SCEch65pNXgzM/brjmvVs1LWQxmx 7ptzb2f5P1bTzxeBldgbsHEznTDFDsQB1ZlMs7tNB53YCiQWc/EoZQ/ZY155n0obqRj2 pogXQUm6uTsUeqi6Wlxm5+Gb2l77/lGl9+bUPYQy/OQaLzpaww12+1lCtEvOKpcQZ7XU iCkIYLZm16W9GrnHj6ew8UyiYo8DSg6o7/qseORx4zXkPwztOO/qBKz/CH+dpePbcI4p KN3nmB1grjUBQN1snUPGzgjElKFR7yFd+n23WIQ2rc22fuZ3oy4LDpGUQHWjLEYrU5j9 ZUNA== X-Gm-Message-State: AOAM531tydxMDWJEWTiO9snvGH5KTIu3ilEaptsmWaYo2R48BIzbBTwV ep5+jOyxYabGYD8aaywnmx1ZfBp0luhZZKF3mSzSCfzaWqbx0y6poarTqvRQ3nLE/FXQ7wOZtcS tj1DTkxQSX3W2bPj/mlueafmIMFlzIYSJK2COrXkU X-Received: by 2002:ac2:43d1:: with SMTP id u17mr12793470lfl.348.1634028371625; Tue, 12 Oct 2021 01:46:11 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzbfo+wRlZQ4toG3xfT67w0misrN1XCgXks2u7IG1JuYC3sMCHZSrIKtMdp5Aamvp7Pxwzc53Wod5ofiphwDE8= X-Received: by 2002:ac2:43d1:: with SMTP id u17mr12793452lfl.348.1634028371392; Tue, 12 Oct 2021 01:46:11 -0700 (PDT) MIME-Version: 1.0 References: <20210913055353.35219-1-jasowang@redhat.com> <20211005032924-mutt-send-email-mst@kernel.org> <20211011082640-mutt-send-email-mst@kernel.org> <20211012012617-mutt-send-email-mst@kernel.org> <20211012022024-mutt-send-email-mst@kernel.org> <20211012030143-mutt-send-email-mst@kernel.org> In-Reply-To: <20211012030143-mutt-send-email-mst@kernel.org> From: Jason Wang Date: Tue, 12 Oct 2021 16:46:00 +0800 Message-ID: Subject: Re: [PATCH 0/9] More virtio hardening To: "Michael S. Tsirkin" Cc: virtualization , linux-kernel , "Hetzelt, Felicitas" , "kaplan, david" , Konrad Rzeszutek Wilk Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 12, 2021 at 3:03 PM Michael S. Tsirkin wrote: > > On Tue, Oct 12, 2021 at 02:43:13PM +0800, Jason Wang wrote: > > On Tue, Oct 12, 2021 at 2:35 PM Michael S. Tsirkin wrote: > > > > > > On Tue, Oct 12, 2021 at 02:11:10PM +0800, Jason Wang wrote: > > > > On Tue, Oct 12, 2021 at 1:44 PM Michael S. Tsirkin wrote: > > > > > > > > > > On Tue, Oct 12, 2021 at 10:43:57AM +0800, Jason Wang wrote: > > > > > > On Mon, Oct 11, 2021 at 8:36 PM Michael S. Tsirkin wrote: > > > > > > > > > > > > > > On Mon, Oct 11, 2021 at 03:36:51PM +0800, Jason Wang wrote: > > > > > > > > On Tue, Oct 5, 2021 at 3:42 PM Michael S. Tsirkin wrote: > > > > > > > > > > > > > > > > > > On Mon, Sep 13, 2021 at 01:53:44PM +0800, Jason Wang wrote: > > > > > > > > > > Hi All: > > > > > > > > > > > > > > > > > > > > This series treis to do more hardening for virito. > > > > > > > > > > > > > > > > > > > > patch 1 validates the num_queues for virio-blk device. > > > > > > > > > > patch 2-4 validates max_nr_ports for virito-console device. > > > > > > > > > > patch 5-7 harden virtio-pci interrupts to make sure no exepcted > > > > > > > > > > interrupt handler is tiggered. If this makes sense we can do similar > > > > > > > > > > things in other transport drivers. > > > > > > > > > > patch 8-9 validate used ring length. > > > > > > > > > > > > > > > > > > > > Smoking test on blk/net with packed=on/off and iommu_platform=on/off. > > > > > > > > > > > > > > > > > > > > Please review. > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > So I poked at console at least, and I think I see > > > > > > > > > an issue: if interrupt handler queues a work/bh, > > > > > > > > > then it can still run while reset is in progress. > > > > > > > > > > > > > > > > Looks like a bug which is unrelated to the hardening? > > > > > > > > > > > > > > Won't preventing use after free be relevant? > > > > > > > > > > > > Oh right. > > > > > > > > > > > > > I frankly don't know what does hardening means then. > > > > > > > > E.g the driver > > > > > > > > should sync with work/bh before reset. > > > > > > > > > > > > > > No, there's no way to fix it ATM without extra locks and state which I > > > > > > > think we should strive to avoid or make it generic, not per-driver, > > > > > > > since sync before reset is useless, new interrupts will just arrive and > > > > > > > queue more work. And a sync after reset is too late since driver will > > > > > > > try to add buffers. > > > > > > > > > > > > Can we do something like > > > > > > > > > > > > 1) disable interrupt > > > > > > 2) sync bh > > > > > > > > > > > > Or I guess this is somehow you meant in the following steps. > > > > > > > > > > So that would mean a new API to disable vq interrupts. > > > > > reset will re-enable. > > > > > E.g. virtqueue_cancel_cb_before_reset()? > > > > > > > > > > Then drivers can sync, then reset. > > > > > This means maintaining more state though, which I don't like. > > > > > > > > > > An alternative is something like this: > > > > > > > > > > static void (*virtio_flush_device)(struct virtio_device *dev); > > > > > > > > > > void virtio_reset_device(struct virtio_device *dev, virtio_flush_device flush) > > > > > { > > > > > might_sleep(); > > > > > if (flush) { > > > > > dev->config->disable_interrupts(dev); > > > > > flush(dev); > > > > > dev->config->reset(dev); > > > > > dev->config->enable_interrupts(dev); > > > > > > > > I wonder whether this is needed. As done in this series, > > > > enable_interrupt should be done in virtio_device_ready(). > > > > > > > > Others should work. > > > > > > > > > } else { > > > > > dev->config->reset(dev); > > > > > } > > > > > } > > > > > > > > > > I have patches wrapping all reset calls in virtio_reset_device > > > > > (without the flush parameter but that's easy to tweak). > > > > > > > > Does it work if I post V2 and you post those patches on top? > > > > > > The reset things? Sure. > > > > Ok. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Maybe we can break device. Two issues with that > > > > > > > - drivers might not be ready to handle add_buf failures > > > > > > > - restore needs to unbreak then and we don't have a way to do that yet > > > > > > > > > > > > > > So .. careful reading of all device drivers and hoping we don't mess > > > > > > > things up even more ... here we come. > > > > > > > > > > > > Yes. > > > > > > > > > > The biggest issue with this trick is drivers not handling add_buf > > > > > errors, adding a failure path here risks creating memory leaks. > > > > > OTOH with e.g. bounce buffers maybe it's possible for add buf to > > > > > fail anyway? > > > > > > > > I'm not sure I get this, a simple git grep told me at least the return > > > > value of add_inbuf() were all checked. > > > > > > > > Thanks > > > > > > Checked locally, but not always error is handled all the way > > > to the top. E.g. add_port in console returns an error code > > > but that is never checked. Well, console is a mess generally. > > > > I see. I can try to audit all virtio drivers for the add_inbuf() case. > > > > Thanks > > Why inbuf specifically? Typo :( > I mean, re-reading code often finds bugs, sure ;) Yes. > > But I don't think just to fix remove we need to audit them all > as such, as long as we are not modifying core, whatever > driver remove we are poking for, that driver needs to be > audited. Right. Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I sent a patch to fix it for console removal specifically, > > > > > > > > > but I suspect it's not enough e.g. freeze is still broken. > > > > > > > > > And note this has been reported without any TDX things - > > > > > > > > > it's not a malicious device issue, can be triggered just > > > > > > > > > by module unload. > > > > > > > > > > > > > > > > > > I am vaguely thinking about new APIs to disable/enable callbacks. > > > > > > > > > An alternative: > > > > > > > > > > > > > > > > > > 1. adding new remove_nocb/freeze_nocb calls > > > > > > > > > 2. disabling/enabling interrupts automatically around these > > > > > > > > > 3. gradually moving devices to using these > > > > > > > > > 4. once/if all device move, removing the old callbacks > > > > > > > > > > > > > > > > > > the advantage here is that we'll be sure calls are always > > > > > > > > > paired correctly. > > > > > > > > > > > > > > > > I'm not sure I get the idea, but my feeling is that it doesn't > > > > > > > > conflict with the interrupt hardening here (or at least the same > > > > > > > > method is required e.g NO_AUTO_EN). > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > Right. It's not that it conflicts, it's that I was hoping that > > > > > > > since you are working on hardening you can take up fixing that. > > > > > > > Let me know whether you have the time. Thanks! > > > > > > > > > > > > I can do that. > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Jason Wang (9): > > > > > > > > > > virtio-blk: validate num_queues during probe > > > > > > > > > > virtio: add doc for validate() method > > > > > > > > > > virtio-console: switch to use .validate() > > > > > > > > > > virtio_console: validate max_nr_ports before trying to use it > > > > > > > > > > virtio_config: introduce a new ready method > > > > > > > > > > virtio_pci: harden MSI-X interrupts > > > > > > > > > > virtio-pci: harden INTX interrupts > > > > > > > > > > virtio_ring: fix typos in vring_desc_extra > > > > > > > > > > virtio_ring: validate used buffer length > > > > > > > > > > > > > > > > > > > > drivers/block/virtio_blk.c | 3 +- > > > > > > > > > > drivers/char/virtio_console.c | 51 +++++++++++++++++++++--------- > > > > > > > > > > drivers/virtio/virtio_pci_common.c | 43 +++++++++++++++++++++---- > > > > > > > > > > drivers/virtio/virtio_pci_common.h | 7 ++-- > > > > > > > > > > drivers/virtio/virtio_pci_legacy.c | 5 +-- > > > > > > > > > > drivers/virtio/virtio_pci_modern.c | 6 ++-- > > > > > > > > > > drivers/virtio/virtio_ring.c | 27 ++++++++++++++-- > > > > > > > > > > include/linux/virtio.h | 1 + > > > > > > > > > > include/linux/virtio_config.h | 6 ++++ > > > > > > > > > > 9 files changed, 118 insertions(+), 31 deletions(-) > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > 2.25.1 > > > > > > > > > > > > > > > > > > > > > > > > >