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 27E50C19F2B for ; Mon, 1 Aug 2022 18:03:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234382AbiHASC7 (ORCPT ); Mon, 1 Aug 2022 14:02:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234269AbiHASCp (ORCPT ); Mon, 1 Aug 2022 14:02:45 -0400 Received: from mail-oi1-x233.google.com (mail-oi1-x233.google.com [IPv6:2607:f8b0:4864:20::233]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5AA8A2AE14 for ; Mon, 1 Aug 2022 11:02:25 -0700 (PDT) Received: by mail-oi1-x233.google.com with SMTP id h125so13892467oif.8 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=BaJU3Uzrs9AkZg0FzzfrIs1RamTpq6yhJL1OlkngceTWpV30TwQWeB/Poskzqoi/bY v7tg2BFzTweOKOXhlSuMeWVGDRIjwPuRbPtRkj2fWJKyUTCULHq9zqPzsGZLhuZ4XkQR FwF7+uc+ORZQR495L0eHVf7t2S8Fk6H7cTsteYB4Eio+whBMQk2a6QqfgEOn9/XsSM9V 7vNGI47cawgcYd5CnKRuTceKtehHlThByk/iNvbjxiqbgptiy9wXKu1bVazXPK3Toxp5 cZ50GWkbJ2/DcjnSLTUFW/MEi2+s5mSEXgOzbISss+oyuf66T9RZfzVkYBNfdWb6St3f FvIg== X-Gm-Message-State: AJIora8YDlNx+pJGZa06DLVMzqkCX37ELIcHVg9zRs4/bNJK+mUDBATu XAhxCFlAKyDAeHEKINJxAJ4cwg== 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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@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 } }; -- 2.30.2