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 554D1C47DA9 for ; Mon, 29 Jan 2024 19:46:28 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rUXZw-0005ld-SQ; Mon, 29 Jan 2024 14:46:00 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rUXZv-0005ky-2R for qemu-devel@nongnu.org; Mon, 29 Jan 2024 14:45:59 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rUXZt-0006yX-4T for qemu-devel@nongnu.org; Mon, 29 Jan 2024 14:45:58 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706557556; 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=2g8qtBVARU0Z78HWQdQNwhHpfTbN5J/ff6aNY2D8M+w=; b=iX9CnGEyanyyor0YtEIBnOGpe/VNs+mCoMHLMnDEMsviMJ3dMyJgB8lsQSHVFsiA8sl5Ig jwYZC3+vBNZOTr/nAQPuGMQ2yAUwVQeg/u0NijcxVyEIiV2MsEO1Xt3r9Ca6RXzayserak CQ7ZT/MPKfF6dSkOnHh7bNaC+HS9Ilw= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-315-A5PFZ2S5P4CNtc5EH8yj4A-1; Mon, 29 Jan 2024 14:45:54 -0500 X-MC-Unique: A5PFZ2S5P4CNtc5EH8yj4A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 63E181C05EAC for ; Mon, 29 Jan 2024 19:45:54 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.51]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A583C1121313; Mon, 29 Jan 2024 19:45:53 +0000 (UTC) Date: Mon, 29 Jan 2024 19:45:51 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Cc: Anthony Harivel , mtosatti@redhat.com, qemu-devel@nongnu.org, vchundur@redhat.com Subject: Re: [PATCH v3 2/3] tools: build qemu-vmsr-helper Message-ID: References: <20240125072214.318382-1-aharivel@redhat.com> <20240125072214.318382-3-aharivel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.3 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.29, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Jan 29, 2024 at 08:33:21PM +0100, Paolo Bonzini wrote: > On Mon, Jan 29, 2024 at 7:53 PM Daniel P. Berrangé wrote: > > > diff --git a/meson.build b/meson.build > > > index d0329966f1b4..93fc233b0891 100644 > > > --- a/meson.build > > > +++ b/meson.build > > > @@ -4015,6 +4015,11 @@ if have_tools > > > dependencies: [authz, crypto, io, qom, qemuutil, > > > libcap_ng, mpathpersist], > > > install: true) > > > + > > > + executable('qemu-vmsr-helper', files('tools/i386/qemu-vmsr-helper.c'), > > > > I'd suggest 'tools/x86/' since this works fine on 64-bit too > > QEMU tends to use i386 in the source to mean both 32- and 64-bit. One day we should rename that to x86 too :-) > > You never answered my question from the previous posting of this > > > > This check is merely validating the the thread ID in the message > > is a child of the process ID connected to the socket. Any process > > on the entire host can satisfy this requirement. > > > > I don't see what is limiting this to only QEMU as claimed by the > > commit message, unless you're expecting the UNIX socket permissions > > to be such that only processes under the qemu:qemu user:group pair > > can access to the socket ? That would be a libvirt based permissions > > assumption though. > > Yes, this is why the systemd socket uses 600, like > contrib/systemd/qemu-pr-helper.socket. The socket can be passed via > SCM_RIGHTS by libvirt, or its permissions can be changed (e.g. 660 and > root:kvm would make sense on a Debian system), or a separate helper > can be started by libvirt. > > Either way, the policy is left to the user rather than embedding it in > the provided systemd unit. Ok, this code needs a comment to explain that we're relying on socket permissions to control who/what can access the daemon, combined with this PID+TID check to validate it is not spoofing its identity, as without context the TID check looks pointless. With 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 :|