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 AA247C2BA15 for ; Mon, 17 Jun 2024 13:15:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sJCC5-0005JU-DZ; Mon, 17 Jun 2024 09:14:46 -0400 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 1sJCC2-0005JG-8x for qemu-devel@nongnu.org; Mon, 17 Jun 2024 09:14:43 -0400 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 1sJCC0-0006cr-BO for qemu-devel@nongnu.org; Mon, 17 Jun 2024 09:14:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1718630078; 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:in-reply-to:in-reply-to: references:references; bh=MRYCUGewdtJETCsAHD7caB1J0V7Rg1cDwaAL6tfgqzU=; b=Slka7zHDM5+gf4wuFh2CnDP5YQY0w2t4e3yhpZmLzcgHtyANLDKcuRBLkmtvmGLSGF8rvd 6S/CYjyPr7ce03oyjSg2Ugvj4soPIZuBmQHhrRPHLwiI4OxtXVRyChcCi5M6ORcWICyyG9 XRcO9Hclwx7j79Xwj93cJrPPa2+VbK4= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-317-qfEfo0hIPQW3nHDyGvPAeg-1; Mon, 17 Jun 2024 09:14:33 -0400 X-MC-Unique: qfEfo0hIPQW3nHDyGvPAeg-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 43AA8195608C; Mon, 17 Jun 2024 13:14:32 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.46]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A36ED1955F2D; Mon, 17 Jun 2024 13:14:26 +0000 (UTC) Date: Mon, 17 Jun 2024 14:14:22 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Konstantin Kostiuk Cc: QEMU , Dehan Meng , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Michael Roth , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Yan Vugenfirer Subject: Re: Guest agent guest-exec memory usage Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 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: 11 X-Spam_score: 1.1 X-Spam_bar: + X-Spam_report: (1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.148, 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, RCVD_IN_SBL_CSS=3.335, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, 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: , 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, Jun 17, 2024 at 04:05:07PM +0300, Konstantin Kostiuk wrote: > Hi All, > > During the investigation of a possible memory leak in the `guest-exec` > command of guest-agent, I found unexpected behavior for me. When we execute > the `guest-exec` command with `capture-output = true`, guest-agent stores > stdout/stderr until someone calls `guest-exec-status`. > > Just for testing, I executed the `man man` command 1000 times with > `capture-output = true` and guest-agent allocated 36Mb to store the results > and it fully depends on output size. > > I want to ask your opinion about this behavior. Is this behavior expected > or not? Should we store all output forever or should we limit it by memory > size/execution time/execution count? If 'guest-exec' is enabled in the agent, this says that the host OS users of the guest-agent are inherently trusted. If they're issuing many guest-exec commands with capture-output = true, and then batching up the calls to guest-exec-status for a later time, that's their perogative and not any worse than other things they can already do with 'guest-exec', such as requesting a fork-bomb. Or to put it another way, if the guest OS admin is worried about malicious usage of 'guest-exec' they should block this command entirely. One of the patches I have in this series: https://lists.nongnu.org/archive/html/qemu-devel/2024-06/threads.html proposes blocking guest-exec by default in the agent, as it is an inherantly risky command to expose. 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 :|