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 D4B1EC433F5 for ; Wed, 27 Apr 2022 20:37:39 +0000 (UTC) Received: from localhost ([::1]:34670 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1njoPq-0000WS-L1 for qemu-devel@archiver.kernel.org; Wed, 27 Apr 2022 16:37:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47192) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njoOq-000805-MF for qemu-devel@nongnu.org; Wed, 27 Apr 2022 16:36:37 -0400 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:46605) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njoOn-000423-Sd for qemu-devel@nongnu.org; Wed, 27 Apr 2022 16:36:35 -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-674-c52dqAGSMtKKvPxdn7VwRg-1; Wed, 27 Apr 2022 16:36:28 -0400 X-MC-Unique: c52dqAGSMtKKvPxdn7VwRg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0E33C85A5BE; Wed, 27 Apr 2022 20:36:28 +0000 (UTC) Received: from bahia (unknown [10.39.195.236]) by smtp.corp.redhat.com (Postfix) with ESMTP id B9E782024CB6; Wed, 27 Apr 2022 20:36:26 +0000 (UTC) Date: Wed, 27 Apr 2022 22:36:25 +0200 From: Greg Kurz To: Christian Schoenebeck Subject: Re: [PATCH v4 2/6] 9pfs: fix qemu_mknodat(S_IFSOCK) on macOS Message-ID: <20220427223625.52e0e23f@bahia> In-Reply-To: <489275615f29a2efc97cbd6130c98669ed28a24b.1651085922.git.qemu_oss@crudebyte.com> References: <489275615f29a2efc97cbd6130c98669ed28a24b.1651085922.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 10.11.54.4 Received-SPF: softfail client-ip=205.139.111.44; 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 Wed, 27 Apr 2022 20:54:17 +0200 Christian Schoenebeck wrote: > mknod() on macOS does not support creating sockets, so divert to > call sequence socket(), bind() and fchmodat() respectively if S_IFSOCK > was passed with mode argument. > > Link: https://lore.kernel.org/qemu-devel/17933734.zYzKuhC07K@silver/ > Signed-off-by: Christian Schoenebeck > --- > hw/9pfs/9p-util-darwin.c | 45 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 44 insertions(+), 1 deletion(-) > > diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c > index e24d09763a..7d00db47a9 100644 > --- a/hw/9pfs/9p-util-darwin.c > +++ b/hw/9pfs/9p-util-darwin.c > @@ -74,6 +74,45 @@ int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name, > */ > #if defined CONFIG_PTHREAD_FCHDIR_NP > > +static int create_socket_file_at_cwd(const char *filename, mode_t mode) { > + int fd, err; > + struct sockaddr_un addr = { > + .sun_family = AF_UNIX > + }; > + > + /* > + * sun_path is only 104 bytes, explicit filename length check required > + */ > + if (sizeof(addr.sun_path) - 1 < strlen(filename) + 2) { True but I was a bit puzzled by the math until I realized the '+ 2' was for the prepended "./" ;-) > + errno = ENAMETOOLONG; > + return -1; > + } > + fd = socket(PF_UNIX, SOCK_DGRAM, 0); > + if (fd == -1) { > + return fd; > + } > + snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", filename); What about the more generic approach of checking snprintf()'s return value ? If it is >= sizeof(addr.sun_path) then truncation occured. > + err = bind(fd, (struct sockaddr *) &addr, sizeof(addr)); > + if (err == -1) { > + goto out; > + } > + /* > + * FIXME: Should rather be using descriptor-based fchmod() on the > + * socket file descriptor above (preferably before bind() call), > + * instead of path-based fchmodat(), to prevent concurrent transient > + * state issues between creating the named FIFO file at bind() and > + * delayed adjustment of permissions at fchmodat(). However currently > + * macOS (12.x) does not support such operations on socket file > + * descriptors yet. > + * > + * Filed report with Apple: FB9997731 > + */ > + err = fchmodat(AT_FDCWD, filename, mode, AT_SYMLINK_NOFOLLOW_ANY); > +out: > + close_preserve_errno(fd); You could close(fd) earlier now, but you might want to keep the code as is in case FB9997731 gets proper attention. Anyway, this should do the job so: Reviewed-by: Greg Kurz > + return err; > +} > + > int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev) > { > int preserved_errno, err; > @@ -93,7 +132,11 @@ int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev) > if (pthread_fchdir_np(dirfd) < 0) { > return -1; > } > - err = mknod(filename, mode, dev); > + if (S_ISSOCK(mode)) { > + err = create_socket_file_at_cwd(filename, mode); > + } else { > + err = mknod(filename, mode, dev); > + } > preserved_errno = errno; > /* Stop using the thread-local cwd */ > pthread_fchdir_np(-1);