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 X-Spam-Level: X-Spam-Status: No, score=-17.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 2F19BC4338F for ; Wed, 18 Aug 2021 08:40:53 +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 CC8206108F for ; Wed, 18 Aug 2021 08:40:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org CC8206108F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:59890 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mGH80-00067N-01 for qemu-devel@archiver.kernel.org; Wed, 18 Aug 2021 04:40:52 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:46324) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mGH6W-0004wJ-5g for qemu-devel@nongnu.org; Wed, 18 Aug 2021 04:39:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:43934) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mGH6T-00026r-Pw for qemu-devel@nongnu.org; Wed, 18 Aug 2021 04:39:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629275956; h=from:from:reply-to: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=DegyRNp/URLsoZwr7RD3DXrKr4CCOJXz5usuQvongB0=; b=AequHLilLTIF+yiVNKJMucvie+fkGsl1viSBlo6xvJ1Jf9WedgX1EQQuNyGr2T6J1seM1v AWG2kT2qp12sRiadVa2+KwMj+BmwS8dxAsUFXLra7MOfxi15qtwaARJx4Pktj5Rnzk0DHm ryac4NQrJTprFe6zSiyx84WPv8Wf6vA= 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-65-FOw7qm9BMQe0PBEZckubhg-1; Wed, 18 Aug 2021 04:39:12 -0400 X-MC-Unique: FOw7qm9BMQe0PBEZckubhg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 75FDC871827 for ; Wed, 18 Aug 2021 08:39:11 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.93]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5CE8A1ACBB; Wed, 18 Aug 2021 08:39:06 +0000 (UTC) Date: Wed, 18 Aug 2021 09:39:03 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Subject: Re: [PATCH 2/2] monitor: Report EBADFD if fdset contains invalid FD Message-ID: References: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Michal Privoznik , qemu-devel Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Aug 17, 2021 at 01:59:22PM +0400, Marc-André Lureau wrote: > Hi > > On Tue, Aug 17, 2021 at 12:56 PM Michal Privoznik > wrote: > > > When opening a path that starts with "/dev/fdset/" the control > > jumps into qemu_parse_fdset() and then into > > monitor_fdset_dup_fd_add(). In here, corresponding fdset is found > > and then all FDs from the set are iterated over trying to find an > > FD that matches expected access mode. For instance, if caller > > wants O_WRONLY then the FD set has to contain an O_WRONLY FD. > > > > If no such FD is found then errno is set to EACCES which results > > in very misleading error messages, for instance: > > > > Could not dup FD for /dev/fdset/3 flags 441: Permission denied > > > > There is no permission issue, the problem is that there was no FD > > within given fdset that was in expected access mode. Therefore, > > let's set errno to EBADFD, which gives us somewhat better > > error messages: > > > > Could not dup FD for /dev/fdset/3 flags 441: File descriptor in bad state > > > > Signed-off-by: Michal Privoznik > > > > I am not sure this is any better. If you try to open a read-only file, the > system also reports EACCES (Permission denied). This is what the current > code models, I believe. If we want better error reporting quality for this method we ought to just stop using errno and wire up a Error **errp parameter. > > > > --- > > monitor/misc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/monitor/misc.c b/monitor/misc.c > > index ffe7966870..a0eda0d574 100644 > > --- a/monitor/misc.c > > +++ b/monitor/misc.c > > @@ -1347,7 +1347,7 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int > > flags) > > } > > > > if (fd == -1) { > > - errno = EACCES; > > + errno = EBADFD; > > return -1; > > } > > > > -- > > 2.31.1 > > > > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|