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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B57C3D6C285 for ; Tue, 19 Nov 2024 18:23:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 385BB6B0088; Tue, 19 Nov 2024 13:23:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 35B396B0089; Tue, 19 Nov 2024 13:23:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 24A566B008A; Tue, 19 Nov 2024 13:23:53 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 0A5776B0088 for ; Tue, 19 Nov 2024 13:23:53 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 72F4CA0738 for ; Tue, 19 Nov 2024 18:23:52 +0000 (UTC) X-FDA: 82803667842.14.C2E6D8D Received: from out-176.mta0.migadu.com (out-176.mta0.migadu.com [91.218.175.176]) by imf15.hostedemail.com (Postfix) with ESMTP id 972E2A0023 for ; Tue, 19 Nov 2024 18:22:58 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=BdCmwlTg; spf=pass (imf15.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.176 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1732040386; h=from:from:sender: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:dkim-signature; bh=rf6WSCMrJOkcRsvsaOzgX4yrr/etHfGHR+l3wYcnl34=; b=p5FYZ7ZBZEaLLyyWhJsXRN1oEPD4Ooc3agbSkkMGHyYgyyiSPhk83RKJIr64Sd/q6owK4L mIYIgSsVxICJC1Hh5MBJCHjuGU9+4jjpJjoUCbCAa9WFcDjj8Z+Qk2odfU574YiI9lWRF2 GwtXS1vW2osbSV/BUa7oyAU58IVmt14= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=BdCmwlTg; spf=pass (imf15.hostedemail.com: domain of roman.gushchin@linux.dev designates 91.218.175.176 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1732040386; a=rsa-sha256; cv=none; b=RNykklDuiOZgm1cTg+g1boBhR5DfvdcOgDU7PhZBWAjJWPzwRA3dM75La6wd9tYP2p4Ace q/i8rDDKxLjbj62dcUlhQF5RhUTyCVO78FUIoB8vsxhg5BIbWckXjfNC4j7P8L1WiCzG32 gwWjJopDXRKQelLoUVcoLlDinN12Ixc= Date: Tue, 19 Nov 2024 18:23:37 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1732040627; 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=rf6WSCMrJOkcRsvsaOzgX4yrr/etHfGHR+l3wYcnl34=; b=BdCmwlTgF/04N1MU0Eyq/59hgreDyKCtmNquOkUG176dQ3JEXimKSzLIShy4EXDl2adRio TNOAZVCy9vETfjieegFPUSeQGvhYVQlwfLBdUHmzOaeH8Se+X5c7jc5EWHafWwm42S7Z+V jwvsMB+WjyH1lymPDI/BB7b0/6dXDTs= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Roman Gushchin To: Pasha Tatashin Cc: Greg KH , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, akpm@linux-foundation.org, corbet@lwn.net, derek.kiernan@amd.com, dragan.cvetic@amd.com, arnd@arndb.de, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, tj@kernel.org, hannes@cmpxchg.org, mhocko@kernel.org, shakeel.butt@linux.dev, muchun.song@linux.dev, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, shuah@kernel.org, vegard.nossum@oracle.com, vattunuru@marvell.com, schalla@marvell.com, david@redhat.com, willy@infradead.org, osalvador@suse.de, usama.anjum@collabora.com, andrii@kernel.org, ryan.roberts@arm.com, peterx@redhat.com, oleg@redhat.com, tandersen@netflix.com, rientjes@google.com, gthelen@google.com Subject: Re: [RFCv1 0/6] Page Detective Message-ID: References: <20241116175922.3265872-1-pasha.tatashin@soleen.com> <2024111938-anointer-kooky-d4f9@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 972E2A0023 X-Stat-Signature: ikmnzukmfnow33rmzmnkjs6cacujtot1 X-Rspam-User: X-HE-Tag: 1732040578-795455 X-HE-Meta: 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 oSZ7V7Tj IVRKljpx4ou6akssT/+Wf0RFQTi8IQ6AoY9I0Wta4pR5Ru8xzDIKvBW2N1jWKaPfpwqMVi77Rm7L40YILbMUh5yGzqyaNgPcXghbAoHj5COHEJP8gWeE4JvrjdCZbSURXKr5rTkBJRhUbVde/69WzYEI6X2Ogd8H/7qgAbb11+hHniHAlIuVsLrPSJILa71YR+Bl9iAryVOjrnk9eoWgY+hMpf33+dNEXxoyZKqRpm00eLpL4fIvXJ7IJV3CrmeT0djKgXcb4WgO2HFM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Nov 19, 2024 at 10:08:36AM -0500, Pasha Tatashin wrote: > On Mon, Nov 18, 2024 at 8:09 PM Greg KH wrote: > > > > On Mon, Nov 18, 2024 at 05:08:42PM -0500, Pasha Tatashin wrote: > > > Additionally, using crash/drgn is not feasible for us at this time, it > > > requires keeping external tools on our hosts, also it requires > > > approval and a security review for each script before deployment in > > > our fleet. > > > > So it's ok to add a totally insecure kernel feature to your fleet > > instead? You might want to reconsider that policy decision :) > > Hi Greg, > > While some risk is inherent, we believe the potential for abuse here > is limited, especially given the existing CAP_SYS_ADMIN requirement. > But, even with root access compromised, this tool presents a smaller > attack surface than alternatives like crash/drgn. It exposes less > sensitive information, unlike crash/drgn, which could potentially > allow reading all of kernel memory. The problem here is with using dmesg for output. No security-sensitive information should go there. Even exposing raw kernel pointers is not considered safe. I'm also not sure about what presents a bigger attack surface. Yes, drgn allows to read more, but it's using /proc/kcore, so the in-kernel code is much simpler. But I don't think it's a relevant discussion, if a malicious user has a root access, there are better options than both drgn and page detective.