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 B761EC433EF for ; Fri, 29 Apr 2022 12:58:39 +0000 (UTC) Received: from localhost ([::1]:52456 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nkQCk-0002VC-JW for qemu-devel@archiver.kernel.org; Fri, 29 Apr 2022 08:58:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38012) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nkQBA-00009c-5S for qemu-devel@nongnu.org; Fri, 29 Apr 2022 08:57:00 -0400 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:44890) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nkQB8-0007H6-4v for qemu-devel@nongnu.org; Fri, 29 Apr 2022 08:56:59 -0400 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-134-qFZ2G55uOPaYDCRQfkdHEg-1; Fri, 29 Apr 2022 08:56:53 -0400 X-MC-Unique: qFZ2G55uOPaYDCRQfkdHEg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 75E45281181B; Fri, 29 Apr 2022 12:56:52 +0000 (UTC) Received: from bahia (unknown [10.39.192.177]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C49940FF6C1; Fri, 29 Apr 2022 12:56:51 +0000 (UTC) Date: Fri, 29 Apr 2022 14:56:50 +0200 From: Greg Kurz To: Christian Schoenebeck Subject: Re: [PATCH v5 2/6] 9pfs: fix qemu_mknodat(S_IFSOCK) on macOS Message-ID: <20220429145650.7d3ba6e8@bahia> In-Reply-To: <2e7b5ecd7a6d83a538db4e8a22d8fb03e9e0f06e.1651228001.git.qemu_oss@crudebyte.com> References: <2e7b5ecd7a6d83a538db4e8a22d8fb03e9e0f06e.1651228001.git.qemu_oss@crudebyte.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 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 Fri, 29 Apr 2022 12:25:11 +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 | 42 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 41 insertions(+), 1 deletion(-) > > diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c > index e24d09763a..619c403ba7 100644 > --- a/hw/9pfs/9p-util-darwin.c > +++ b/hw/9pfs/9p-util-darwin.c > @@ -74,6 +74,42 @@ 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 > + }; > + > + err = snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", filename); > + if (err < 0 || err >= sizeof(addr.sun_path)) { According to POSIX [1]: The snprintf() function shall fail if: [EOVERFLOW] [CX] [Option Start] The value of n is greater than {INT_MAX}. [Option End] [1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html Since we're passing sizeof(addr.sun_path), I'm pretty sure snprintf() cannot fail. No big deal. Reviewed-by: Greg Kurz > + errno = ENAMETOOLONG; > + return -1; > + } > + fd = socket(PF_UNIX, SOCK_DGRAM, 0); > + if (fd == -1) { > + return fd; > + } > + 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); > + return err; > +} > + > int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev) > { > int preserved_errno, err; > @@ -93,7 +129,11 @@ 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);