From patchwork Tue Jul 7 18:45:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 278262 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08047C433DF for ; Tue, 7 Jul 2020 18:47:35 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CE392206E2 for ; Tue, 7 Jul 2020 18:47:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="AtudMlL2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CE392206E2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54736 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jsscw-0007rI-42 for qemu-devel@archiver.kernel.org; Tue, 07 Jul 2020 14:47:34 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41868) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jssb8-00058x-EU for qemu-devel@nongnu.org; Tue, 07 Jul 2020 14:45:42 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:29680 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jssb6-0007F7-5q for qemu-devel@nongnu.org; Tue, 07 Jul 2020 14:45:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594147539; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gR59wA1IW8js6Hw+yLL7CoKyJyCyFu9O9hAYxwg3x/g=; b=AtudMlL2idEYCZyB0XmO9431jxX06UeYQhYDnq/aOPXEPc/tLO1AxPj0xpPWlIdfJ1JRfh 0C/L+3DWZULPEsSxI6KnUw/s3h3IVaPTw+WaIkPHRyJqPA+t8CE6M30wHxRTwWX9AvwKp1 DsmN0CSw05Z0fKjwsQrdEEDP1rLU+PQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-148-PmzJJ0vkMFCZwxRWW8bRDg-1; Tue, 07 Jul 2020 14:45:36 -0400 X-MC-Unique: PmzJJ0vkMFCZwxRWW8bRDg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E73A68015CE; Tue, 7 Jul 2020 18:45:35 +0000 (UTC) Received: from thinkpad.redhat.com (ovpn-112-252.ams2.redhat.com [10.36.112.252]) by smtp.corp.redhat.com (Postfix) with ESMTP id 121DB61981; Tue, 7 Jul 2020 18:45:23 +0000 (UTC) From: Laurent Vivier To: qemu-devel@nongnu.org Subject: [PATCH v4 1/2] net: check if the file descriptor is valid before using it Date: Tue, 7 Jul 2020 20:45:14 +0200 Message-Id: <20200707184515.371476-2-lvivier@redhat.com> In-Reply-To: <20200707184515.371476-1-lvivier@redhat.com> References: <20200707184515.371476-1-lvivier@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lvivier@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.120; envelope-from=lvivier@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/07 06:04:49 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , =?utf-8?q?Daniel_P=2E_Berrang?= =?utf-8?b?w6k=?= , Stefan Weil , Jason Wang , Markus Armbruster , Gerd Hoffmann , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?b?w6k=?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" qemu_set_nonblock() checks that the file descriptor can be used and, if not, crashes QEMU. An assert() is used for that. The use of assert() is used to detect programming error and the coredump will allow to debug the problem. But in the case of the tap device, this assert() can be triggered by a misconfiguration by the user. At startup, it's not a real problem, but it can also happen during the hot-plug of a new device, and here it's a problem because we can crash a perfectly healthy system. For instance: # ip link add link virbr0 name macvtap0 type macvtap mode bridge # ip link set macvtap0 up # TAP=/dev/tap$(ip -o link show macvtap0 | cut -d: -f1) # qemu-system-x86_64 -machine q35 -device pcie-root-port,id=pcie-root-port-0 -monitor stdio 9<> $TAP (qemu) netdev_add type=tap,id=hostnet0,vhost=on,fd=9 (qemu) device_add driver=virtio-net-pci,netdev=hostnet0,id=net0,bus=pcie-root-port-0 (qemu) device_del net0 (qemu) netdev_del hostnet0 (qemu) netdev_add type=tap,id=hostnet1,vhost=on,fd=9 qemu-system-x86_64: .../util/oslib-posix.c:247: qemu_set_nonblock: Assertion `f != -1' failed. Aborted (core dumped) To avoid that, add a function, qemu_try_set_nonblock(), that allows to report the problem without crashing. In the same way, we also update the function for vhostfd in net_init_tap_one() and for fd in net_init_socket() (both descriptors are provided by the user and can be wrong). Signed-off-by: Laurent Vivier Reviewed-by: Philippe Mathieu-Daudé --- include/qemu/sockets.h | 1 + net/socket.c | 9 +++++-- net/tap.c | 25 +++++++++++++++--- util/oslib-posix.c | 26 +++++++++++++------ util/oslib-win32.c | 57 ++++++++++++++++++++++++------------------ 5 files changed, 79 insertions(+), 39 deletions(-) diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h index 57cd049d6edd..7d1f8135767d 100644 --- a/include/qemu/sockets.h +++ b/include/qemu/sockets.h @@ -18,6 +18,7 @@ int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen); int socket_set_cork(int fd, int v); int socket_set_nodelay(int fd); void qemu_set_block(int fd); +int qemu_try_set_nonblock(int fd); void qemu_set_nonblock(int fd); int socket_set_fast_reuse(int fd); diff --git a/net/socket.c b/net/socket.c index c92354049bca..2d21fddd9cd6 100644 --- a/net/socket.c +++ b/net/socket.c @@ -725,13 +725,18 @@ int net_init_socket(const Netdev *netdev, const char *name, } if (sock->has_fd) { - int fd; + int fd, ret; fd = monitor_fd_param(cur_mon, sock->fd, errp); if (fd == -1) { return -1; } - qemu_set_nonblock(fd); + ret = qemu_try_set_nonblock(fd); + if (ret < 0) { + error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d", + name, fd); + return -1; + } if (!net_socket_fd_init(peer, "socket", name, fd, 1, sock->mcast, errp)) { return -1; diff --git a/net/tap.c b/net/tap.c index 6207f61f84ab..41a20102fd0b 100644 --- a/net/tap.c +++ b/net/tap.c @@ -689,6 +689,8 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer, } if (vhostfdname) { + int ret; + vhostfd = monitor_fd_param(cur_mon, vhostfdname, &err); if (vhostfd == -1) { if (tap->has_vhostforce && tap->vhostforce) { @@ -698,7 +700,12 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer, } return; } - qemu_set_nonblock(vhostfd); + ret = qemu_try_set_nonblock(vhostfd); + if (ret < 0) { + error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d", + name, fd); + return; + } } else { vhostfd = open("/dev/vhost-net", O_RDWR); if (vhostfd < 0) { @@ -766,6 +773,7 @@ int net_init_tap(const Netdev *netdev, const char *name, Error *err = NULL; const char *vhostfdname; char ifname[128]; + int ret = 0; assert(netdev->type == NET_CLIENT_DRIVER_TAP); tap = &netdev->u.tap; @@ -795,7 +803,12 @@ int net_init_tap(const Netdev *netdev, const char *name, return -1; } - qemu_set_nonblock(fd); + ret = qemu_try_set_nonblock(fd); + if (ret < 0) { + error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d", + name, fd); + return -1; + } vnet_hdr = tap_probe_vnet_hdr(fd); @@ -810,7 +823,6 @@ int net_init_tap(const Netdev *netdev, const char *name, char **fds; char **vhost_fds; int nfds = 0, nvhosts = 0; - int ret = 0; if (tap->has_ifname || tap->has_script || tap->has_downscript || tap->has_vnet_hdr || tap->has_helper || tap->has_queues || @@ -843,7 +855,12 @@ int net_init_tap(const Netdev *netdev, const char *name, goto free_fail; } - qemu_set_nonblock(fd); + ret = qemu_try_set_nonblock(fd); + if (ret < 0) { + error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d", + name, fd); + goto free_fail; + } if (i == 0) { vnet_hdr = tap_probe_vnet_hdr(fd); diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 916f1be2243a..149254cd691f 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -253,25 +253,35 @@ void qemu_set_block(int fd) assert(f != -1); } -void qemu_set_nonblock(int fd) +int qemu_try_set_nonblock(int fd) { int f; f = fcntl(fd, F_GETFL); - assert(f != -1); - f = fcntl(fd, F_SETFL, f | O_NONBLOCK); -#ifdef __OpenBSD__ if (f == -1) { + return -errno; + } + if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) { +#ifdef __OpenBSD__ /* * Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on * memory devices and sets errno to ENODEV. * It's OK if we fail to set O_NONBLOCK on devices like /dev/null, * because they will never block anyway. */ - assert(errno == ENODEV); - } -#else - assert(f != -1); + if (errno == ENODEV) { + return 0; + } #endif + return -errno; + } + return 0; +} + +void qemu_set_nonblock(int fd) +{ + int f; + f = qemu_try_set_nonblock(fd); + assert(f == 0); } int socket_set_fast_reuse(int fd) diff --git a/util/oslib-win32.c b/util/oslib-win32.c index e9b14ab17847..5548ce6038f3 100644 --- a/util/oslib-win32.c +++ b/util/oslib-win32.c @@ -132,31 +132,6 @@ struct tm *localtime_r(const time_t *timep, struct tm *result) } #endif /* CONFIG_LOCALTIME_R */ -void qemu_set_block(int fd) -{ - unsigned long opt = 0; - WSAEventSelect(fd, NULL, 0); - ioctlsocket(fd, FIONBIO, &opt); -} - -void qemu_set_nonblock(int fd) -{ - unsigned long opt = 1; - ioctlsocket(fd, FIONBIO, &opt); - qemu_fd_register(fd); -} - -int socket_set_fast_reuse(int fd) -{ - /* Enabling the reuse of an endpoint that was used by a socket still in - * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows - * fast reuse is the default and SO_REUSEADDR does strange things. So we - * don't have to do anything here. More info can be found at: - * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */ - return 0; -} - - static int socket_error(void) { switch (WSAGetLastError()) { @@ -233,6 +208,38 @@ static int socket_error(void) } } +void qemu_set_block(int fd) +{ + unsigned long opt = 0; + WSAEventSelect(fd, NULL, 0); + ioctlsocket(fd, FIONBIO, &opt); +} + +int qemu_try_set_nonblock(int fd) +{ + unsigned long opt = 1; + if (ioctlsocket(fd, FIONBIO, &opt) != NO_ERROR) { + return -socket_error(); + } + qemu_fd_register(fd); + return 0; +} + +void qemu_set_nonblock(int fd) +{ + (void)qemu_try_set_nonblock(fd); +} + +int socket_set_fast_reuse(int fd) +{ + /* Enabling the reuse of an endpoint that was used by a socket still in + * TIME_WAIT state is usually performed by setting SO_REUSEADDR. On Windows + * fast reuse is the default and SO_REUSEADDR does strange things. So we + * don't have to do anything here. More info can be found at: + * http://msdn.microsoft.com/en-us/library/windows/desktop/ms740621.aspx */ + return 0; +} + int inet_aton(const char *cp, struct in_addr *ia) { uint32_t addr = inet_addr(cp); From patchwork Tue Jul 7 18:45:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 278263 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2D15C433E0 for ; Tue, 7 Jul 2020 18:46:38 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 90598206E2 for ; Tue, 7 Jul 2020 18:46:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ivCN/d47" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90598206E2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:50650 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jssc1-0006Bd-RL for qemu-devel@archiver.kernel.org; Tue, 07 Jul 2020 14:46:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41908) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jssbD-0005Et-Hy for qemu-devel@nongnu.org; Tue, 07 Jul 2020 14:45:47 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:42523 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jssbB-0007HR-AH for qemu-devel@nongnu.org; Tue, 07 Jul 2020 14:45:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594147544; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+nzwBgn8WZJCUar8t/jicCXKYmZx0jwwgVx0UYtsLgI=; b=ivCN/d47IBrDWlr8aR5mHaAe27wpjY+YBGLkilHzCfGRGWFftKUI0Qr+GlNvynnrhK8fkR J+62FbtCj4GaHscGxfcvDbrZpAuPCHQXGyOVMgvTF4lGWlq3mwTdi9MuX4jn6HrveviY8a f9Qxk7rVFJgdQWLqxd33ny9cBqBSKbk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-250-8a8CP9daNtmp5jX0_nxIpg-1; Tue, 07 Jul 2020 14:45:42 -0400 X-MC-Unique: 8a8CP9daNtmp5jX0_nxIpg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A8398100A61E; Tue, 7 Jul 2020 18:45:41 +0000 (UTC) Received: from thinkpad.redhat.com (ovpn-112-252.ams2.redhat.com [10.36.112.252]) by smtp.corp.redhat.com (Postfix) with ESMTP id 47A9260CC0; Tue, 7 Jul 2020 18:45:36 +0000 (UTC) From: Laurent Vivier To: qemu-devel@nongnu.org Subject: [PATCH v4 2/2] net: detect errors from probing vnet hdr flag for TAP devices Date: Tue, 7 Jul 2020 20:45:15 +0200 Message-Id: <20200707184515.371476-3-lvivier@redhat.com> In-Reply-To: <20200707184515.371476-1-lvivier@redhat.com> References: <20200707184515.371476-1-lvivier@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lvivier@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.61; envelope-from=lvivier@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/07 00:31:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , =?utf-8?q?Daniel_P=2E_Berrang?= =?utf-8?b?w6k=?= , Stefan Weil , Jason Wang , Markus Armbruster , "Dr . David Alan Gilbert" , Gerd Hoffmann , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?b?w6k=?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: "Daniel P. Berrange" When QEMU sets up a tap based network device backend, it mostly ignores errors reported from various ioctl() calls it makes, assuming the TAP file descriptor is valid. This assumption can easily be violated when the user is passing in a pre-opened file descriptor. At best, the ioctls may fail with a -EBADF, but if the user passes in a bogus FD number that happens to clash with a FD number that QEMU has opened internally for another reason, a wide variety of errnos may result, as the TUNGETIFF ioctl number may map to a completely different command on a different type of file. By ignoring all these errors, QEMU sets up a zombie network backend that will never pass any data. Even worse, when QEMU shuts down, or that network backend is hot-removed, it will close this bogus file descriptor, which could belong to another QEMU device backend. There's no obvious guaranteed reliable way to detect that a FD genuinely is a TAP device, as opposed to a UNIX socket, or pipe, or something else. Checking the errno from probing vnet hdr flag though, does catch the big common cases. ie calling TUNGETIFF will return EBADF for an invalid FD, and ENOTTY when FD is a UNIX socket, or pipe which catches accidental collisions with FDs used for stdio, or monitor socket. Previously the example below where bogus fd 9 collides with the FD used for the chardev saw: $ ./x86_64-softmmu/qemu-system-x86_64 -netdev tap,id=hostnet0,fd=9 \ -chardev socket,id=charchannel0,path=/tmp/qga,server,nowait \ -monitor stdio -vnc :0 qemu-system-x86_64: -netdev tap,id=hostnet0,fd=9: TUNGETIFF ioctl() failed: Inappropriate ioctl for device TUNSETOFFLOAD ioctl() failed: Bad address QEMU 2.9.1 monitor - type 'help' for more information (qemu) Warning: netdev hostnet0 has no peer which gives a running QEMU with a zombie network backend. With this change applied we get an error message and QEMU immediately exits before carrying on and making a bigger disaster: $ ./x86_64-softmmu/qemu-system-x86_64 -netdev tap,id=hostnet0,fd=9 \ -chardev socket,id=charchannel0,path=/tmp/qga,server,nowait \ -monitor stdio -vnc :0 qemu-system-x86_64: -netdev tap,id=hostnet0,vhost=on,fd=9: Unable to query TUNGETIFF on FD 9: Inappropriate ioctl for device Reported-by: Dr. David Alan Gilbert Signed-off-by: Daniel P. Berrange Tested-by: Dr. David Alan Gilbert Message-id: 20171027085548.3472-1-berrange@redhat.com [lv: to simplify, don't check on EINVAL with TUNGETIFF as it exists since v2.6.27] Signed-off-by: Laurent Vivier --- net/tap-bsd.c | 2 +- net/tap-linux.c | 8 +++++--- net/tap-solaris.c | 2 +- net/tap-stub.c | 2 +- net/tap.c | 25 ++++++++++++++++++++----- net/tap_int.h | 2 +- 6 files changed, 29 insertions(+), 12 deletions(-) diff --git a/net/tap-bsd.c b/net/tap-bsd.c index a5c3707f806d..77aaf674b19d 100644 --- a/net/tap-bsd.c +++ b/net/tap-bsd.c @@ -211,7 +211,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) { } -int tap_probe_vnet_hdr(int fd) +int tap_probe_vnet_hdr(int fd, Error **errp) { return 0; } diff --git a/net/tap-linux.c b/net/tap-linux.c index e0dd442ee34f..b0635e9e32ce 100644 --- a/net/tap-linux.c +++ b/net/tap-linux.c @@ -147,13 +147,15 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) } } -int tap_probe_vnet_hdr(int fd) +int tap_probe_vnet_hdr(int fd, Error **errp) { struct ifreq ifr; if (ioctl(fd, TUNGETIFF, &ifr) != 0) { - error_report("TUNGETIFF ioctl() failed: %s", strerror(errno)); - return 0; + /* TUNGETIFF is available since kernel v2.6.27 */ + error_setg_errno(errp, errno, + "Unable to query TUNGETIFF on FD %d", fd); + return -1; } return ifr.ifr_flags & IFF_VNET_HDR; diff --git a/net/tap-solaris.c b/net/tap-solaris.c index 4725d2314eef..ae2ba6828415 100644 --- a/net/tap-solaris.c +++ b/net/tap-solaris.c @@ -206,7 +206,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) { } -int tap_probe_vnet_hdr(int fd) +int tap_probe_vnet_hdr(int fd, Error **errp) { return 0; } diff --git a/net/tap-stub.c b/net/tap-stub.c index a9ab8f829362..de525a2e69d4 100644 --- a/net/tap-stub.c +++ b/net/tap-stub.c @@ -37,7 +37,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp) { } -int tap_probe_vnet_hdr(int fd) +int tap_probe_vnet_hdr(int fd, Error **errp) { return 0; } diff --git a/net/tap.c b/net/tap.c index 41a20102fd0b..b37ccae00cd3 100644 --- a/net/tap.c +++ b/net/tap.c @@ -597,7 +597,11 @@ int net_init_bridge(const Netdev *netdev, const char *name, } qemu_set_nonblock(fd); - vnet_hdr = tap_probe_vnet_hdr(fd); + vnet_hdr = tap_probe_vnet_hdr(fd, errp); + if (vnet_hdr < 0) { + close(fd); + return -1; + } s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr); snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper, @@ -810,7 +814,11 @@ int net_init_tap(const Netdev *netdev, const char *name, return -1; } - vnet_hdr = tap_probe_vnet_hdr(fd); + vnet_hdr = tap_probe_vnet_hdr(fd, errp); + if (vnet_hdr < 0) { + close(fd); + return -1; + } net_init_tap_one(tap, peer, "tap", name, NULL, script, downscript, @@ -863,8 +871,11 @@ int net_init_tap(const Netdev *netdev, const char *name, } if (i == 0) { - vnet_hdr = tap_probe_vnet_hdr(fd); - } else if (vnet_hdr != tap_probe_vnet_hdr(fd)) { + vnet_hdr = tap_probe_vnet_hdr(fd, errp); + if (vnet_hdr < 0) { + goto free_fail; + } + } else if (vnet_hdr != tap_probe_vnet_hdr(fd, NULL)) { error_setg(errp, "vnet_hdr not consistent across given tap fds"); ret = -1; @@ -909,7 +920,11 @@ free_fail: } qemu_set_nonblock(fd); - vnet_hdr = tap_probe_vnet_hdr(fd); + vnet_hdr = tap_probe_vnet_hdr(fd, errp); + if (vnet_hdr < 0) { + close(fd); + return -1; + } net_init_tap_one(tap, peer, "bridge", name, ifname, script, downscript, vhostfdname, diff --git a/net/tap_int.h b/net/tap_int.h index e3194b23f47d..225a49ea4843 100644 --- a/net/tap_int.h +++ b/net/tap_int.h @@ -34,7 +34,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen); void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp); -int tap_probe_vnet_hdr(int fd); +int tap_probe_vnet_hdr(int fd, Error **errp); int tap_probe_vnet_hdr_len(int fd, int len); int tap_probe_has_ufo(int fd); void tap_fd_set_offload(int fd, int csum, int tso4, int tso6, int ecn, int ufo);