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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 CE2E2C742D2 for ; Sun, 14 Jul 2019 14:37:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 A35912063F for ; Sun, 14 Jul 2019 14:37:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="F8CKt40+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A35912063F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5tVDknZM1PQTd/tAoueNiO8Put9qClnvbFOjuIE5jUU=; b=F8CKt40+4qjjd/ JLLXvBzasGheUfskCmCZRpiMK9knCHfkTJremjdKgB9Gdx7kwoT4/nV9kMWI/+EPFX51IfmgMEKmN 9IDnJcunMt3HOLk+MgmYs8px4kzV+n5yqBpuk3QeYrxkFkXS8bQC3AeS896F+atxi9991k0qR6L9y XMUvVJvDMhYJ5kBrjVzdXnw+40ejHGQ8LERndyGVCw9SxKPRl/Tzh5ZuLu7o9NYuhFrMNFwtFUbV9 A2sxQJTEych739Kpl52Vc03TAfc+t2jgCPg/sMlQ+n6YhqGmNUlSF8/f4qzlg/sHxtIrjJa2FHGYd NyAkpPwhsKSsQHPoRLyw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hmfcZ-0001KC-RY; Sun, 14 Jul 2019 14:36:59 +0000 Received: from zeniv.linux.org.uk ([195.92.253.2]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hmfcW-0001Jh-IW for linux-arm-kernel@lists.infradead.org; Sun, 14 Jul 2019 14:36:58 +0000 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hmfbz-00010j-Kc; Sun, 14 Jul 2019 14:36:23 +0000 Date: Sun, 14 Jul 2019 15:36:23 +0100 From: Al Viro To: Aleksa Sarai Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags Message-ID: <20190714143623.GR17978@ZenIV.linux.org.uk> References: <20190706145737.5299-1-cyphar@cyphar.com> <20190706145737.5299-6-cyphar@cyphar.com> <20190712043341.GI17978@ZenIV.linux.org.uk> <20190712105745.nruaftgeat6irhzr@yavin> <20190712123924.GK17978@ZenIV.linux.org.uk> <20190712125552.GL17978@ZenIV.linux.org.uk> <20190712132553.GN17978@ZenIV.linux.org.uk> <20190712150026.GO17978@ZenIV.linux.org.uk> <20190713024153.GA3817@ZenIV.linux.org.uk> <20190714070029.m53etvm3y4etidxt@yavin> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190714070029.m53etvm3y4etidxt@yavin> User-Agent: Mutt/1.11.3 (2019-02-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190714_073656_617738_DBC63AF9 X-CRM114-Status: UNSURE ( 8.82 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Alexei Starovoitov , linux-kernel@vger.kernel.org, David Howells , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Tycho Andersen , Aleksa Sarai , linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, Kees Cook , Arnd Bergmann , Jann Horn , linuxppc-dev@lists.ozlabs.org, linux-m68k@lists.linux-m68k.org, Andy Lutomirski , Shuah Khan , David Drysdale , Christian Brauner , "J. Bruce Fields" , linux-parisc@vger.kernel.org, linux-api@vger.kernel.org, Chanho Min , Jeff Layton , Oleg Nesterov , Eric Biederman , linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Jul 14, 2019 at 05:00:29PM +1000, Aleksa Sarai wrote: > The basic property being guaranteed by LOOKUP_IN_ROOT is that it will > not result in resolution of a path component which was not inside the > root of the dirfd tree at some point during resolution (and that all > absolute symlink and ".." resolution will be done relative to the > dirfd). This may smell slightly of chroot(2), because unfortunately it > is a similar concept -- the reason for this is to allow for a more > efficient way to safely resolve paths inside a rootfs than spawning a > separate process to then pass back the fd to the caller. IDGI... If attacker can modify your subtree, you have already lost - after all, they can make anything appear inside that tree just before your syscall is made and bring it back out immediately afterwards. And if they can't, what is the race you are trying to protect against? Confused... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel