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 52303C433FE for ; Thu, 21 Apr 2022 07:46:08 +0000 (UTC) Received: from localhost ([::1]:44014 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nhRVu-0000tm-2m for qemu-devel@archiver.kernel.org; Thu, 21 Apr 2022 03:46:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33186) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nhRHQ-0001jr-1r for qemu-devel@nongnu.org; Thu, 21 Apr 2022 03:31:09 -0400 Received: from us-smtp-delivery-44.mimecast.com ([207.211.30.44]:42487) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nhRHN-00070u-MA for qemu-devel@nongnu.org; Thu, 21 Apr 2022 03:31:07 -0400 Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-447-Ez8d8KZ5OyaqbZXonerkAQ-1; Thu, 21 Apr 2022 03:30:59 -0400 X-MC-Unique: Ez8d8KZ5OyaqbZXonerkAQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7D967802803; Thu, 21 Apr 2022 07:30:58 +0000 (UTC) Received: from bahia (unknown [10.39.192.169]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4B646111E3E9; Thu, 21 Apr 2022 07:30:57 +0000 (UTC) Date: Thu, 21 Apr 2022 09:30:56 +0200 From: Greg Kurz To: Christian Schoenebeck Subject: Re: [PATCH 3/5] 9pfs: fix wrong encoding of rdev field in Rgetattr on macOS Message-ID: <20220421093056.5ab1e7ed@bahia> In-Reply-To: <9db9268aac4eb87e1471ab8240109c7c29be3bef.1650370027.git.qemu_oss@crudebyte.com> References: <9db9268aac4eb87e1471ab8240109c7c29be3bef.1650370027.git.qemu_oss@crudebyte.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 Received-SPF: softfail client-ip=207.211.30.44; envelope-from=groug@kaod.org; helo=us-smtp-delivery-44.mimecast.com 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_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_SOFTFAIL=0.665, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: , Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org, Keno Fischer , Michael Roitzsch , Will Cohen , Akihiko Odaki Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 19 Apr 2022 13:41:15 +0200 Christian Schoenebeck wrote: > The 'rdev' field in 9p reponse 'Rgetattr' is of type dev_t, > which is actually a system dependant type and therefore both the > size and encoding of dev_t differ between macOS and Linux. > > So far we have sent 'rdev' to guest in host's dev_t format as-is, > which caused devices to appear with wrong device numbers on > guests running on macOS hosts, eventually leading to various > misbehaviours on guest in conjunction with device files. > > This patch fixes this issue by converting the device number from > host's dev_t format to Linux dev_t format. As 9p request > 'Tgettattr' is exclusive to protocol version 9p2000.L, it should > be fair to assume that 'rdev' field is assumed to be in Linux dev_t > format by client as well. > For the sake of accuracy : this is converting the host's dev_t to glibc's format (MMMM_Mmmm_mmmM_MMmm, 64 bits) actually, which is compatible with linux's format (mmmM_MMmm, 32 bits), as described in . > Signed-off-by: Christian Schoenebeck > --- > hw/9pfs/9p.c | 37 ++++++++++++++++++++++++++++++++++++- > 1 file changed, 36 insertions(+), 1 deletion(-) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index 225f31fc31..d953035e1c 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -1318,6 +1318,41 @@ static int32_t stat_to_iounit(const V9fsPDU *pdu, const struct stat *stbuf) > return blksize_to_iounit(pdu, stbuf->st_blksize); > } > > +#if !defined(CONFIG_LINUX) > + > +/* > + * Generates a Linux device number (a.k.a. dev_t) for given device major > + * and minor numbers. > + */ > +static uint64_t makedev_dotl(uint32_t dev_major, uint32_t dev_minor) > +{ > + uint64_t dev; > + > + // from glibc sysmacros.h: > + dev = (((uint64_t) (dev_major & 0x00000fffu)) << 8); > + dev |= (((uint64_t) (dev_major & 0xfffff000u)) << 32); > + dev |= (((uint64_t) (dev_minor & 0x000000ffu)) << 0); > + dev |= (((uint64_t) (dev_minor & 0xffffff00u)) << 12); > + return dev; > +} > + > +#endif > + > +/* > + * Converts given device number from host's device number format to Linux > + * device number format. As both the size of type dev_t and encoding of > + * dev_t is system dependant, we have to convert them for Linux guests if > + * host is not running Linux. > + */ > +static uint64_t host_dev_to_dotl_dev(dev_t dev) > +{ > +#ifdef CONFIG_LINUX > + return dev; > +#else > + return makedev_dotl(major(dev), minor(dev)); > +#endif > +} > + It is a bit unfortunate to inflate 9p.c, which is large enough, with glue code. Even if they are only used here, I'd personally put them in 9p-util.h. No big deal. Reviewed-by: Greg Kurz > static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, > V9fsStatDotl *v9lstat) > { > @@ -1327,7 +1362,7 @@ static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf, > v9lstat->st_nlink = stbuf->st_nlink; > v9lstat->st_uid = stbuf->st_uid; > v9lstat->st_gid = stbuf->st_gid; > - v9lstat->st_rdev = stbuf->st_rdev; > + v9lstat->st_rdev = host_dev_to_dotl_dev(stbuf->st_rdev); > v9lstat->st_size = stbuf->st_size; > v9lstat->st_blksize = stat_to_iounit(pdu, stbuf); > v9lstat->st_blocks = stbuf->st_blocks;