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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 9F4EFEB64DC for ; Mon, 26 Jun 2023 07:28:40 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qDgdd-0001xq-Lb; Mon, 26 Jun 2023 03:27:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qDgda-0001xh-3D for qemu-devel@nongnu.org; Mon, 26 Jun 2023 03:27:50 -0400 Received: from 7.mo552.mail-out.ovh.net ([188.165.59.253]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qDgdX-00056b-Ad for qemu-devel@nongnu.org; Mon, 26 Jun 2023 03:27:49 -0400 Received: from mxplan5.mail.ovh.net (unknown [10.108.1.10]) by mo552.mail-out.ovh.net (Postfix) with ESMTPS id 2F0912A5EA; Mon, 26 Jun 2023 07:27:37 +0000 (UTC) Received: from kaod.org (37.59.142.97) by DAG6EX1.mxp5.local (172.16.2.51) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Mon, 26 Jun 2023 09:27:36 +0200 Authentication-Results: garm.ovh; auth=pass (GARM-97G0024af44f21-cb43-45ac-86ff-635e80a015eb, 5C4EAD3502E8E3551B4A3CEBFDB3E85F9E4F3318) smtp.auth=groug@kaod.org X-OVh-ClientIp: 78.197.208.248 Date: Mon, 26 Jun 2023 09:27:35 +0200 From: Greg Kurz To: Christian Schoenebeck CC: , "Daniel P. =?UTF-8?B?QmVycmFuZ8Op?=" Subject: Re: [SPAM] [PATCH v4] 9pfs: deprecate 'proxy' backend Message-ID: <20230626092735.2b27565e@bahia> In-Reply-To: References: X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [37.59.142.97] X-ClientProxiedBy: DAG9EX1.mxp5.local (172.16.2.81) To DAG6EX1.mxp5.local (172.16.2.51) X-Ovh-Tracer-GUID: cb9006d9-ef87-40c2-ad55-a78241fe5f5b X-Ovh-Tracer-Id: 4461096907599616477 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvhedrgeehvddgjeegucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecuhedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepfffhvfevuffkjghfofggtgfgihesthejredtredtvdenucfhrhhomhepifhrvghgucfmuhhriicuoehgrhhouhhgsehkrghougdrohhrgheqnecuggftrfgrthhtvghrnhepgfdufeeuieegveeiudejueeivefhueeivdekleekteekkeekgedvheehuedvhefgnecuffhomhgrihhnpehqvghmuhdrohhrghdpghhithhlrggsrdgtohhmpdhgihhthhhusgdrtghomhenucfkphepuddvjedrtddrtddruddpfeejrdehledrudegvddrleejpdejkedrudeljedrvddtkedrvdegkeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeduvdejrddtrddtrddupdhmrghilhhfrhhomhepoehgrhhouhhgsehkrghougdrohhrgheqpdhnsggprhgtphhtthhopedupdhrtghpthhtohepqhgvmhhupghoshhssegtrhhuuggvsgihthgvrdgtohhmpdhqvghmuhdquggvvhgvlhesnhhonhhgnhhurdhorhhgpdgsvghrrhgrnhhgvgesrhgvughhrghtrdgtohhmpdfovfetjfhoshhtpehmohehhedvpdhmohguvgepshhmthhpohhuth Received-SPF: pass client-ip=188.165.59.253; envelope-from=groug@kaod.org; helo=7.mo552.mail-out.ovh.net X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, 23 Jun 2023 14:41:15 +0200 Christian Schoenebeck wrote: > As recent CVE-2023-2861 once again showed, the 9p 'proxy' fs driver is in > bad shape. Using the 'proxy' backend was already discouraged for safety > reasons before and we recommended to use the 'local' backend (preferably > in conjunction with its 'mapped' security model) instead, but now it is > time to officially deprecate the 'proxy' backend. > > Signed-off-by: Christian Schoenebeck > --- > v3 -> v4: > - MAINTAINERS: also move virtfs-proxy-helper.rst to 'obsolete' section > - deprecated.rst: suggest virtiofsd as alternative. > - deprecated.rst: mention a considerable future reimplementation of > 'proxy' using 'vhost'. > - QEMU runtime warning: merge deprecation warnings of '-virtfs proxy' and > '-fsdev proxy' into a single deprecation warning and mention virtiofsd > as alternative. > - virtfs-proxy-helper daemon: print runtime deprecation warning here as > well. > - commit log: mention 'mapped' security model. > > MAINTAINERS | 9 ++++++++- > docs/about/deprecated.rst | 23 +++++++++++++++++++++++ > docs/tools/virtfs-proxy-helper.rst | 3 +++ > fsdev/qemu-fsdev.c | 8 ++++++++ > fsdev/virtfs-proxy-helper.c | 9 +++++++++ > hw/9pfs/9p-proxy.c | 5 +++++ > hw/9pfs/9p-proxy.h | 5 +++++ > meson.build | 2 +- > qemu-options.hx | 6 +++++- > 9 files changed, 67 insertions(+), 3 deletions(-) > > diff --git a/MAINTAINERS b/MAINTAINERS > index 436b3f0afe..3aa70b5c21 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -2118,13 +2118,20 @@ S: Odd Fixes > W: https://wiki.qemu.org/Documentation/9p > F: hw/9pfs/ > X: hw/9pfs/xen-9p* > +X: hw/9pfs/9p-proxy* > F: fsdev/ > -F: docs/tools/virtfs-proxy-helper.rst > +X: fsdev/virtfs-proxy-helper.c > F: tests/qtest/virtio-9p-test.c > F: tests/qtest/libqos/virtio-9p* > T: git https://gitlab.com/gkurz/qemu.git 9p-next > T: git https://github.com/cschoenebeck/qemu.git 9p.next > > +virtio-9p-proxy > +F: hw/9pfs/9p-proxy* > +F: fsdev/virtfs-proxy-helper.c > +F: docs/tools/virtfs-proxy-helper.rst > +S: Obsolete > + > virtio-blk > M: Stefan Hajnoczi > L: qemu-block@nongnu.org > diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst > index 0743459862..4ce75722f3 100644 > --- a/docs/about/deprecated.rst > +++ b/docs/about/deprecated.rst > @@ -343,6 +343,29 @@ the addition of volatile memory support, it is now necessary to distinguish > between persistent and volatile memory backends. As such, memdev is deprecated > in favor of persistent-memdev. > > +``-fsdev proxy`` and ``-virtfs proxy`` (since 8.1) > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +The 9p ``proxy`` filesystem backend driver has been deprecated and will be > +removed (along with its proxy helper daemon) in a future version of QEMU. Please > +use ``-fsdev local`` or ``-virtfs local`` for using the 9p ``local`` filesystem > +backend instead, or alternatively consider deploying virtiofsd instead. Maybe drop the first "instead" to avoid repetition ? > + > +The 9p ``proxy`` backend was originally developed as an alternative to the 9p > +``local`` backend. The idea was to enhance security by dispatching actual low > +level filesystem operations from 9p server (QEMU process) over to a separate > +process (the virtfs-proxy-helper binary). However this alternative never gained > +momentum. The proxy backend is much slower than the local backend, hasn't seen > +any development in years, and showed to be less secure, especially due to the > +fact that its helper daemon must be run as root, whereas with the local backend > +QEMU is typically run as unprivileged user and allows to tighten behaviour by > +mapping permissions et al by using its 'mapped' security model option. > + > +Nowadays it would make sense to reimplement the ``proxy`` backend by using > +QEMU's ``vhost`` feature, which would eliminate the high latency costs under > +which the 9p ``proxy`` backend currently suffers. However as of to date nobody > +has indicated plans for such kind of reimplemention unfortunately. > + > > Block device options > '''''''''''''''''''' > diff --git a/docs/tools/virtfs-proxy-helper.rst b/docs/tools/virtfs-proxy-helper.rst > index 6cdeedf8e9..bd310ebb07 100644 > --- a/docs/tools/virtfs-proxy-helper.rst > +++ b/docs/tools/virtfs-proxy-helper.rst > @@ -9,6 +9,9 @@ Synopsis > Description > ----------- > > +NOTE: The 9p 'proxy' backend is deprecated (since QEMU 8.1) and will be > +removed, along with this daemon, in a future version of QEMU! > + > Pass-through security model in QEMU 9p server needs root privilege to do > few file operations (like chown, chmod to any mode/uid:gid). There are two > issues in pass-through security model: > diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c > index 3da64e9f72..9a50ee370b 100644 > --- a/fsdev/qemu-fsdev.c > +++ b/fsdev/qemu-fsdev.c > @@ -133,6 +133,14 @@ int qemu_fsdev_add(QemuOpts *opts, Error **errp) > } > > if (fsdriver) { > + if (strncmp(fsdriver, "proxy", 5) == 0) { > + warn_report( > + "'-fsdev proxy' and '-virtfs proxy' are deprecated, use " > + "'local' instead of 'proxy, or consider deploying virtiofsd " > + "instead" Ditto. LGTM. Reviewed-by: Greg Kurz > + ); > + } > + > for (i = 0; i < ARRAY_SIZE(FsDrivers); i++) { > if (strcmp(FsDrivers[i].name, fsdriver) == 0) { > break; > diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c > index d9511f429c..144aaf585a 100644 > --- a/fsdev/virtfs-proxy-helper.c > +++ b/fsdev/virtfs-proxy-helper.c > @@ -9,6 +9,11 @@ > * the COPYING file in the top-level directory. > */ > > +/* > + * NOTE: The 9p 'proxy' backend is deprecated (since QEMU 8.1) and will be > + * removed in a future version of QEMU! > + */ > + > #include "qemu/osdep.h" > #include > #include > @@ -1057,6 +1062,10 @@ int main(int argc, char **argv) > struct statfs st_fs; > #endif > > + fprintf(stderr, "NOTE: The 9p 'proxy' backend is deprecated (since " > + "QEMU 8.1) and will be removed in a future version of " > + "QEMU!\n"); > + > prog_name = g_path_get_basename(argv[0]); > > is_daemon = true; > diff --git a/hw/9pfs/9p-proxy.c b/hw/9pfs/9p-proxy.c > index 99d115ff0d..905cae6992 100644 > --- a/hw/9pfs/9p-proxy.c > +++ b/hw/9pfs/9p-proxy.c > @@ -15,6 +15,11 @@ > * https://wiki.qemu.org/Documentation/9p > */ > > +/* > + * NOTE: The 9p 'proxy' backend is deprecated (since QEMU 8.1) and will be > + * removed in a future version of QEMU! > + */ > + > #include "qemu/osdep.h" > #include > #include > diff --git a/hw/9pfs/9p-proxy.h b/hw/9pfs/9p-proxy.h > index b84301d001..9be4718d3e 100644 > --- a/hw/9pfs/9p-proxy.h > +++ b/hw/9pfs/9p-proxy.h > @@ -10,6 +10,11 @@ > * the COPYING file in the top-level directory. > */ > > +/* > + * NOTE: The 9p 'proxy' backend is deprecated (since QEMU 8.1) and will be > + * removed in a future version of QEMU! > + */ > + > #ifndef QEMU_9P_PROXY_H > #define QEMU_9P_PROXY_H > > diff --git a/meson.build b/meson.build > index 34306a6205..05c01b72bb 100644 > --- a/meson.build > +++ b/meson.build > @@ -4170,7 +4170,7 @@ if have_block > summary_info += {'Block whitelist (ro)': get_option('block_drv_ro_whitelist')} > summary_info += {'Use block whitelist in tools': get_option('block_drv_whitelist_in_tools')} > summary_info += {'VirtFS (9P) support': have_virtfs} > - summary_info += {'VirtFS (9P) Proxy Helper support': have_virtfs_proxy_helper} > + summary_info += {'VirtFS (9P) Proxy Helper support (deprecated)': have_virtfs_proxy_helper} > summary_info += {'Live block migration': config_host_data.get('CONFIG_LIVE_BLOCK_MIGRATION')} > summary_info += {'replication support': config_host_data.get('CONFIG_REPLICATION')} > summary_info += {'bochs support': get_option('bochs').allowed()} > diff --git a/qemu-options.hx b/qemu-options.hx > index b57489d7ca..3a6c7d3ef9 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -1735,7 +1735,9 @@ SRST > Accesses to the filesystem are done by QEMU. > > ``proxy`` > - Accesses to the filesystem are done by virtfs-proxy-helper(1). > + Accesses to the filesystem are done by virtfs-proxy-helper(1). This > + option is deprecated (since QEMU 8.1) and will be removed in a future > + version of QEMU. Use ``local`` instead. > > ``synth`` > Synthetic filesystem, only used by QTests. > @@ -1867,6 +1869,8 @@ SRST > > ``proxy`` > Accesses to the filesystem are done by virtfs-proxy-helper(1). > + This option is deprecated (since QEMU 8.1) and will be removed in a > + future version of QEMU. Use ``local`` instead. > > ``synth`` > Synthetic filesystem, only used by QTests. -- Greg