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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 25572ECE58C for ; Mon, 7 Oct 2019 16:43:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F063B206BB for ; Mon, 7 Oct 2019 16:43:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="FpFHy4pe" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728925AbfJGQnG (ORCPT ); Mon, 7 Oct 2019 12:43:06 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:39583 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728081AbfJGQnG (ORCPT ); Mon, 7 Oct 2019 12:43:06 -0400 Received: by mail-pg1-f196.google.com with SMTP id e1so8544432pgj.6 for ; Mon, 07 Oct 2019 09:43:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=DqRaKKb4MIDZkPIzMIF26YB72N9deabH6QrKCDZ4VYg=; b=FpFHy4peK4L70f64OcM9wSee5GAAbdr7kct1DpldnL87yT1hCZqb7C0VCWf4+b4t1K m2Gt4RHACh7KJdMxbnHVgbHN1E4eyp46IJDFySJl5gKSaXFspgau0JGltITbFAd10qr5 k8+hb7KPJHZfyhXXVhSQ6D1YpEZc4SIh8jKU5f4BX6qF3jvaSKNSs4290NYCBD3FaEhF /KbgTDIx7dE2pzirfxZS+3aXejWSaw9I8blAqhnR4ud6KZxHgIy5UyX0KlgR9xucLRTo zmcEl/M5GRgA9u7h0aY5OIFpHjdeySpzLImv3Y8Kq2GizltfOww40DIfER4lL3+YQyXT MiZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=DqRaKKb4MIDZkPIzMIF26YB72N9deabH6QrKCDZ4VYg=; b=dzRnJg1BaWM41+d7AA3Fbt0LJ7tVRdDRhmkQm40q8WVVh8LR/Ya63TUff24aYVBWS3 v/xIJyA1xSstG3C5uAaeDS9mcF7LdpC2+tifjmRge30dXJgr49E49CuBSVEJ7Ls4YK0R 5qaPkX7lOxIURzBnOwQlVGqb8YgIRw7vLkLD7qgoPZgyYpR4N8HKFnsErpOpl0/7wWff ukIxnxUywUjg2SYdyjQQubl7D9k81XPUx3CXJbga7Gw22pUXFGa7szGsdsswmvH5IDwh Am2C7TdCRGXrwadmULxqg4Hwl/ao2EtgYccDRJ8ymAHHGMf2QYTCYmhx/oyZ711p4IL5 4usA== X-Gm-Message-State: APjAAAWnPxoOxHexTU0/c+5U7k8MDVU3pBzpMei3TgkKwOknWLyErVww QQKj6FBG35/jgJ2KWYBykIA9hQ== X-Google-Smtp-Source: APXvYqyIFfiIX8M8ZKiZ25hUlwGaFhNL6pVrJMMdwvYiiyg8No4RMZKuFIF8exLb9Ld1x7axYzWV+A== X-Received: by 2002:a63:e558:: with SMTP id z24mr6194458pgj.379.1570466585019; Mon, 07 Oct 2019 09:43:05 -0700 (PDT) Received: from nebulus.mtv.corp.google.com ([2620:15c:211:200:5404:91ba:59dc:9400]) by smtp.googlemail.com with ESMTPSA id k5sm14054281pgb.11.2019.10.07.09.43.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Oct 2019 09:43:04 -0700 (PDT) Subject: Re: [PATCH] ovl: filter of trusted xattr results in audit To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, linux-security-module@vger.kernel.org, stable@vger.kernel.org, Miklos Szeredi , linux-unionfs@vger.kernel.org References: <20191007160918.29504-1-salyzyn@android.com> <20191007161616.GA988623@kroah.com> <20191007161725.GB988623@kroah.com> <20191007164037.GA1012698@kroah.com> From: Mark Salyzyn Message-ID: <75330715-b83c-fa26-5dbd-745f71e9d592@android.com> Date: Mon, 7 Oct 2019 09:43:03 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191007164037.GA1012698@kroah.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/7/19 9:40 AM, Greg Kroah-Hartman wrote: > On Mon, Oct 07, 2019 at 06:17:25PM +0200, Greg Kroah-Hartman wrote: >> On Mon, Oct 07, 2019 at 06:16:16PM +0200, Greg Kroah-Hartman wrote: >>> On Mon, Oct 07, 2019 at 09:09:16AM -0700, Mark Salyzyn wrote: >>>> When filtering xattr list for reading, presence of trusted xattr >>>> results in a security audit log. However, if there is other content >>>> no errno will be set, and if there isn't, the errno will be -ENODATA >>>> and not -EPERM as is usually associated with a lack of capability. >>>> The check does not block the request to list the xattrs present. >>>> >>>> Switch to has_capability_noaudit to reflect a more appropriate check. >>>> >>>> Signed-off-by: Mark Salyzyn >>>> Cc: linux-security-module@vger.kernel.org >>>> Cc: kernel-team@android.com >>>> Cc: Greg Kroah-Hartman >>>> Cc: stable@vger.kernel.org # v3.18 >>>> Fixes: upstream a082c6f680da ("ovl: filter trusted xattr for non-admin") >>>> Fixes: 3.18 4bcc9b4b3a0a ("ovl: filter trusted xattr for non-admin") >>>> --- >>>> Replaced ns_capable_noaudit with 3.18.y tree specific >>>> has_capability_noaudit present in original submission to kernel.org >>>> commit 5c2e9f346b815841f9bed6029ebcb06415caf640 >>>> ("ovl: filter of trusted xattr results in audit") >>>> >>>> fs/overlayfs/inode.c | 3 ++- >>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c >>>> index a01ec1836a72..1175efa5e956 100644 >>>> --- a/fs/overlayfs/inode.c >>>> +++ b/fs/overlayfs/inode.c >>>> @@ -265,7 +265,8 @@ static bool ovl_can_list(const char *s) >>>> return true; >>>> >>>> /* Never list trusted.overlay, list other trusted for superuser only */ >>>> - return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); >>>> + return !ovl_is_private_xattr(s) && >>>> + has_capability_noaudit(current, CAP_SYS_ADMIN); >>>> } >>>> >>>> ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) >>>> -- >>>> 2.23.0.581.g78d2f28ef7-goog >>>> >>> Thanks for the backport, this one worked! >> I spoke too soon: >> >> ERROR: "has_capability_noaudit" [fs/overlayfs/overlay.ko] undefined! >> >> That function isn't exported for modules :( > But, if this really is needed, and it fixes the issue, I'll go export > that symbol with EXPORT_SYMBOL_GPL() to fix the problem. Any > objections? > > thanks, > > greg k-h Ok, you just answered my question in cross-emails. Yes, EXPORT_SYMBOL_GPL() (my option 2). Thanks -- Mark Salyzyn