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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 062FAC433EF for ; Wed, 20 Jul 2022 14:58:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241077AbiGTO6A (ORCPT ); Wed, 20 Jul 2022 10:58:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35746 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237462AbiGTO56 (ORCPT ); Wed, 20 Jul 2022 10:57:58 -0400 Received: from mail-oi1-x235.google.com (mail-oi1-x235.google.com [IPv6:2607:f8b0:4864:20::235]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C61314AD47 for ; Wed, 20 Jul 2022 07:57:56 -0700 (PDT) Received: by mail-oi1-x235.google.com with SMTP id p132so11143275oif.9 for ; Wed, 20 Jul 2022 07:57:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=XSU2WUPOvF0fUCTGSGRZkl8WCZhfSChGKTGTEOsuYNI=; b=iGIpbP2d3UEwVFWw5G9dZlMqJx4o8UCPvRj6piZLN7Qixwv38zIteUBoiwtf11TzoJ 8pcI1FzJmEI8s8Z8r4wNd/P56A7AMD40p0ifu6Z8wqaycmhnxl9M7kNdXzB8SXogNKD/ YVqd80JtH2cgsBKx3SUf9wdgi1qit4j7Py/II= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=XSU2WUPOvF0fUCTGSGRZkl8WCZhfSChGKTGTEOsuYNI=; b=j4/w5olrx4e7wFpPwaNW2D4g22R+YOj3gpuOa/chvDO2Xa1DzqzXq6gmOo9ndikAKj 0IPmhGcaaOH4SL+GM9UJGlyycTDTmi4J17bxU7GGtH50WVcFwHa8IRSVInH4CfyxHOQh YfbgmfzahsbLeQGJgiAZ4PZnEVFG8JomSJ8fzKxkPAzmRGTu2CTJTTHuAh4tYDiis6iC hrVczoPesbQjk4BvKGxrwRnON3D6K5j85cHcucvM6ntAQepE7VeObs7Qj0sLnN4A9+Xk KCgHO2ZBPTNWMgkCC6DA2r39V+YEz2+yce7H6OFvXEcbqgTEFkRTELvjWrnJMGOdAxAm g+nA== X-Gm-Message-State: AJIora9dTsFvO55J3MYlJaAqs54S6MUlEdfR1JoUXYUg3d2gfJgki877 AzxwGWtivE7Tre9tOjNPivS8+w== X-Google-Smtp-Source: AGRyM1v5UNxUPAVexBnv65PVVqbWvE8t6MWf9AqqczcauOBSa7XBiaehpgEh3k3h5n6IkYivB27NLA== X-Received: by 2002:a05:6808:170c:b0:335:1d14:f99d with SMTP id bc12-20020a056808170c00b003351d14f99dmr2435919oib.243.1658329076048; Wed, 20 Jul 2022 07:57:56 -0700 (PDT) Received: from [192.168.0.41] ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id z14-20020a9d62ce000000b0061c7a5691f2sm7425058otk.47.2022.07.20.07.57.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Jul 2022 07:57:55 -0700 (PDT) Message-ID: <42069251-3ea7-b0c7-4efb-e144c52ebf51@cloudflare.com> Date: Wed, 20 Jul 2022 09:57:53 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2 4/4] selinux: Implement create_user_ns hook Content-Language: en-US To: Paul Moore Cc: kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, shuah@kernel.org, brauner@kernel.org, casey@schaufler-ca.com, ebiederm@xmission.com, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com References: <20220707223228.1940249-1-fred@cloudflare.com> <20220707223228.1940249-5-fred@cloudflare.com> From: Frederick Lawler In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 7/19/22 8:32 PM, Paul Moore wrote: > On Thu, Jul 7, 2022 at 6:32 PM Frederick Lawler wrote: >> >> Unprivileged user namespace creation is an intended feature to enable >> sandboxing, however this feature is often used to as an initial step to >> perform a privilege escalation attack. >> >> This patch implements a new namespace { userns_create } access control >> permission to restrict which domains allow or deny user namespace >> creation. This is necessary for system administrators to quickly protect >> their systems while waiting for vulnerability patches to be applied. >> >> This permission can be used in the following way: >> >> allow domA_t domB_t : namespace { userns_create }; >> >> Signed-off-by: Frederick Lawler >> >> --- >> Changes since v1: >> - Introduce this patch >> --- >> security/selinux/hooks.c | 9 +++++++++ >> security/selinux/include/classmap.h | 2 ++ >> 2 files changed, 11 insertions(+) >> >> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >> index beceb89f68d9..73fbcb434fe0 100644 >> --- a/security/selinux/hooks.c >> +++ b/security/selinux/hooks.c >> @@ -4227,6 +4227,14 @@ static void selinux_task_to_inode(struct task_struct *p, >> spin_unlock(&isec->lock); >> } >> >> +static int selinux_userns_create(const struct cred *cred) >> +{ >> + u32 sid = current_sid(); >> + >> + return avc_has_perm(&selinux_state, sid, sid, SECCLASS_NAMESPACE, >> + NAMESPACE__USERNS_CREATE, NULL); >> +} > > As we continue to discuss this, I'm beginning to think that having a > dedicated object class for the userns might be a good idea. I believe > I was the one who gave you these code snippets, so feel free to blame > me for the respin ;) > No worries, I'll make this change for v3. > This is what I'm thinking: > > static int selinux_userns_create(const struct cred *cred) > { > u32 sid = current_sid(); > > return avc_has_perm(&selinux_state, sid, sid, > SECCLASS_USER_NAMESPACE, > USER_NAMESPACE__CREATE, NULL); > } > >> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h >> index ff757ae5f253..9943e85c6b3e 100644 >> --- a/security/selinux/include/classmap.h >> +++ b/security/selinux/include/classmap.h >> @@ -254,6 +254,8 @@ const struct security_class_mapping secclass_map[] = { >> { COMMON_FILE_PERMS, NULL } }, >> { "io_uring", >> { "override_creds", "sqpoll", NULL } }, >> + { "namespace", >> + { "userns_create", NULL } }, > > The above would need to change to: > > { "user_namespace", > { "create", NULL } } >