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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9270DC43143 for ; Fri, 22 Jun 2018 07:47:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 423B423E5B for ; Fri, 22 Jun 2018 07:47:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 423B423E5B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751250AbeFVHr3 convert rfc822-to-8bit (ORCPT ); Fri, 22 Jun 2018 03:47:29 -0400 Received: from mail-ot0-f194.google.com ([74.125.82.194]:39884 "EHLO mail-ot0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbeFVHr2 (ORCPT ); Fri, 22 Jun 2018 03:47:28 -0400 Received: by mail-ot0-f194.google.com with SMTP id l15-v6so6511423oth.6 for ; Fri, 22 Jun 2018 00:47:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Iyn30l9fde7x/pZ4JHMEIRjg/CWn3zVgPaWp6ysGwM0=; b=gh3xwTl8aiemGI954KI7MpoHcrEJByUuHC8fHJmcuKKO6/tDIxZ42XrFz+1dkroHls QeqQfhsjGogJh8M9tNj3ucRrb3gZnNQxOsgNn8kLSNFWt1ifpJ193Dthi8RkWTLbYbBY WN6AUwrkqOU/Mgz5zUvgmuQCE1BjAvyUuKIqk729T2a4kqh1jJEyL6E1Em5A+MVO0wQD vnknvhnH+n6Wc/YbwyYRkW0Su/QZJ6jERRPEztgskiY8jWX3/QlupgkB5BPnjGJKBd3n uc0FBm0cloIwCgT7+PEe5MDNW6oXs1gvolyj+tb7oSVxwXHUbMxrMA13pWQNCalCsRf0 iGfg== X-Gm-Message-State: APt69E08z5W4VS8AopD/jO3ZRKwMTz6szuQSfIfqpmw4rPy9olI3nc0u Eme9C6cO8Zt9D8m7MgY/JFyZBrI3C1Tv52+DZCn5iQ== X-Google-Smtp-Source: ADUXVKItHq6FZo5qWBtWd2/71jrnd8NJK/LwjqEVZX718URoObyUVmKMPMc3TQCNXk713PMnHZlp88gJcICD+2OoX/c= X-Received: by 2002:a9d:17ce:: with SMTP id j72-v6mr322723otj.244.1529653647475; Fri, 22 Jun 2018 00:47:27 -0700 (PDT) MIME-Version: 1.0 References: <20180621083316.8765-1-omosnace@redhat.com> In-Reply-To: From: Ondrej Mosnacek Date: Fri, 22 Jun 2018 09:47:16 +0200 Message-ID: Subject: Re: [PATCH -next] cred: conditionally declare groups-related functions To: Paul Moore Cc: akpm@linux-foundation.org, rdunlap@infradead.org, sfr@canb.auug.org.au, Eric Paris , Linux kernel mailing list , linux-next@vger.kernel.org, Linux-Audit Mailing List Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org št 21. 6. 2018 o 23:17 Paul Moore napísal(a): > > On Thu, Jun 21, 2018 at 4:33 AM Ondrej Mosnacek wrote: > > > > The groups-related functions declared in include/linux/cred.h are > > defined in kernel/groups.c, which is compiled only when > > CONFIG_MULTIUSER=y. Move all these function declarations under #ifdef > > CONFIG_MULTIUSER to help avoid accidental usage in contexts where > > CONFIG_MULTIUSER might be disabled. > > > > This patch also adds a fallback for groups_search(). Currently this > > function is only called from kernel/groups.c itself and > > keys/permissions.c, which depends on CONFIG_MULTIUSER. However, the > > audit subsystem (which does not depend on CONFIG_MULTIUSER) calls this > > function in -next, so the fallback will be needed to avoid compilation > > errors or ugly workarounds. > > > > See also: > > https://lkml.org/lkml/2018/6/20/670 > > https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git/commit/?h=next&id=af85d1772e31fed34165a1b3decef340cf4080c0 > > > > Reported-by: Randy Dunlap > > Signed-off-by: Ondrej Mosnacek > > --- > > include/linux/cred.h | 16 +++++++++++----- > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/include/linux/cred.h b/include/linux/cred.h > > index 631286535d0f..8917768453cc 100644 > > --- a/include/linux/cred.h > > +++ b/include/linux/cred.h > > @@ -65,6 +65,12 @@ extern void groups_free(struct group_info *); > > > > extern int in_group_p(kgid_t); > > extern int in_egroup_p(kgid_t); > > + > > +extern int set_current_groups(struct group_info *); > > +extern void set_groups(struct cred *, struct group_info *); > > +extern int groups_search(const struct group_info *, kgid_t); > > +extern bool may_setgroups(void); > > +extern void groups_sort(struct group_info *); > > #else > > static inline void groups_free(struct group_info *group_info) > > { > > @@ -78,12 +84,12 @@ static inline int in_egroup_p(kgid_t grp) > > { > > return 1; > > } > > + > > +static inline int groups_search(const struct group_info *group_info, kgid_t grp) > > +{ > > + return 0; > > Is this the right fallback value? If CONFIG_MULTIUSER is disabled, > wouldn't we always want to indicate a group match? The in_group_p() > and in_egroup_p() dummy functions would seem to indicate that is the > correct behavior ... Hm, indeed this is a bit tricky and I'm guilty of not noticing this... The way I see it (now that I though about it a little), there are basically two possible semantics of groups_search(): 1. as an (auxiliary) permissions checking function (like in_[e]group_p()) -- in this case we would expect the same return value as in_group_p(), i.e. 1. 2. as a function that simply checks if a group is contained in a list of groups (taken from a cred struct) -- in this case we would expect it to return 0 in single-user mode, since there will be always no supplemental groups set for any task (if I understand it right). I guess no matter which semantic we pick, we might confuse someone expecting the other one, so I would suggest dropping this patch (or at least the fallbacks for groups_search) and explicitly handle the single-user case in audit. We should probably default to 1 in audit anyway, because the original code used in_[e]group_p(). Even though 0 would seem more logical to me, comparing GIDs doesn't really make sense in single-user mode anyway, so keeping the legacy behavior will be safer. (In fact now that I think of it, having audit enabled (or even compiled) in single-user mode does not make much sense either... maybe we should just make CONFIG_AUDIT depend on CONFIG_MULTIUSER...). > > > +} > > #endif > > -extern int set_current_groups(struct group_info *); > > -extern void set_groups(struct cred *, struct group_info *); > > -extern int groups_search(const struct group_info *, kgid_t); > > -extern bool may_setgroups(void); > > -extern void groups_sort(struct group_info *); > > > > /* > > * The security context of a task > > -- > > 2.17.1 > > > > > -- > paul moore > www.paul-moore.com -- Ondrej Mosnacek Associate Software Engineer, Security Technologies Red Hat, Inc.