From patchwork Mon Aug 1 18:01:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12933969 X-Patchwork-Delegate: paul@paul-moore.com 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 AB091C00144 for ; Mon, 1 Aug 2022 18:03:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234377AbiHASC7 (ORCPT ); Mon, 1 Aug 2022 14:02:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234268AbiHASCp (ORCPT ); Mon, 1 Aug 2022 14:02:45 -0400 Received: from mail-oi1-x22f.google.com (mail-oi1-x22f.google.com [IPv6:2607:f8b0:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A6082A704 for ; Mon, 1 Aug 2022 11:02:25 -0700 (PDT) Received: by mail-oi1-x22f.google.com with SMTP id s204so13921397oif.5 for ; Mon, 01 Aug 2022 11:02:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=bttyVQI+o0yCdSSwfTGsmfJypexzzz/Ptc7wrcpVb94=; b=i4ToQg1x5/k2OuSwcs5fz8zHz6WBhwfxswzE6nWWdWaeEdPc6pv10CDx0N+HMBM9Yj apKtW+hsRPgAXYA0BTvzit4oSXA5q0fwJgMIOswGMI+7uQRvQtuNrIn2Q8ZTP+qQUF4U PXAMRMONfHRrue6t5Oi+zRbQrpqKUBZwty/Yw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=bttyVQI+o0yCdSSwfTGsmfJypexzzz/Ptc7wrcpVb94=; b=D0AzEwng0ohkAkiE/VMrrCwNKuXT/QW1fuIvqKpFKMN+85mTsI35QSmtllHZ3LuQHq ZoHG5BxoxdfJo61noTxSsMjix+lZibo6hGQVQrS0fWSf8sqGL9z0t18QArD/yzuRvFe1 AMnO7Vu564ZfE5+Ozl8odBNN0MUcdvaKWHEaO93A4fZV7Kp8cKEScDHOp4sw8b8NXlwj 7guYzSATRnMy00Sr/UGnUTpY9GiSdnWxE2+LZKoBIThVFkC4pbiHxWiTFh6llEibOrjD Zanjd8cePRkkmH7fyos2Aq1KNl+CaXH7JBFScRLFU1x2dO4CdxqufJ6ScnPsq761c1aW Ec+A== X-Gm-Message-State: AJIora9vGRzBj8STP+RAjvGLhX2fypgAjizKYWXRshpWlcR+MlRBuyw6 Uhw9LivcuE1fbmZvY6PFwLItiQ== X-Google-Smtp-Source: AGRyM1tirTjWfZIcvEpccIMwd00O49IfF8uA6bm3mVQLc9R6zclPg5zxqFpIZPvVpdHR1RhSA9mPug== X-Received: by 2002:a05:6808:302b:b0:2f9:eeef:f03 with SMTP id ay43-20020a056808302b00b002f9eeef0f03mr6998147oib.128.1659376942519; Mon, 01 Aug 2022 11:02:22 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id n14-20020a9d64ce000000b00618fa37308csm2881348otl.35.2022.08.01.11.02.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Aug 2022 11:02:22 -0700 (PDT) From: Frederick Lawler To: 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, paul@paul-moore.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 Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com, cgzones@googlemail.com, karl@bigbadwolfsecurity.com, Frederick Lawler Subject: [PATCH v4 4/4] selinux: Implement userns_create hook Date: Mon, 1 Aug 2022 13:01:46 -0500 Message-Id: <20220801180146.1157914-5-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220801180146.1157914-1-fred@cloudflare.com> References: <20220801180146.1157914-1-fred@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org 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 user_namespace { 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 domA_t : user_namespace { create }; Signed-off-by: Frederick Lawler --- Changes since v3: - None Changes since v2: - Rename create_user_ns hook to userns_create - Use user_namespace as an object opposed to a generic namespace object - s/domB_t/domA_t in commit message 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..afc9da0249e7 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_USER_NAMESPACE, + USER_NAMESPACE__CREATE, NULL); +} + /* Returns error only if unable to parse addresses */ static int selinux_parse_skb_ipv4(struct sk_buff *skb, struct common_audit_data *ad, u8 *proto) @@ -7117,6 +7125,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(task_movememory, selinux_task_movememory), LSM_HOOK_INIT(task_kill, selinux_task_kill), LSM_HOOK_INIT(task_to_inode, selinux_task_to_inode), + LSM_HOOK_INIT(userns_create, selinux_userns_create), LSM_HOOK_INIT(ipc_permission, selinux_ipc_permission), LSM_HOOK_INIT(ipc_getsecid, selinux_ipc_getsecid), diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index ff757ae5f253..0bff55bb9cde 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 } }, + { "user_namespace", + { "create", NULL } }, { NULL } };