From patchwork Thu Jul 21 17:28:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12925645 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 EEE17C43334 for ; Thu, 21 Jul 2022 17:29:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231383AbiGUR3F (ORCPT ); Thu, 21 Jul 2022 13:29:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231666AbiGUR2k (ORCPT ); Thu, 21 Jul 2022 13:28:40 -0400 Received: from mail-oa1-x30.google.com (mail-oa1-x30.google.com [IPv6:2001:4860:4864:20::30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 402E98AEC2 for ; Thu, 21 Jul 2022 10:28:22 -0700 (PDT) Received: by mail-oa1-x30.google.com with SMTP id 586e51a60fabf-10d83692d5aso3338663fac.1 for ; Thu, 21 Jul 2022 10:28:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=9XmM5ZEm+shFY9USkb0JIud5sKeKc0ztWjPwdUbLtVM=; b=VxN5mqJJldqCTmzCQx2+zgcmh2YQ/eQWRZOCH3SSk/wgcplWOs9zda4bzFvX0e/y3I w3O6v0xE9QlSb5O7mcwsd7nUKfGQMW+kAGmKMdQ3s/MptadnTYQWw5YHyzVxhn0Qdra7 /HkKK7hh0AG+o5x79m4ZlAOsEEJPLxCywqt50= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=9XmM5ZEm+shFY9USkb0JIud5sKeKc0ztWjPwdUbLtVM=; b=deX/P0p49QSPD7wyZziBQB4LeJ9ezntCXBrDSq9mQd6Y5cy04B5RFB0xT0+qAIeAJ7 8wrjm4R6Qqc97MiH/bNocpNHBTtGEXndIrAhHUrtNSE8karm14DOROolwZwcqm4FPCHw Q2ILMjvGGDMM2HzcZ/ojfNNnrPuHAiK5wwKFkrDBhPvPQCnP5RyWmUFr4Wrt7AN0RjAO wQC7cHlUliZb3fwcwmNwwEFZj6ifxugX6Eodi2hfjYIaC36l2n0wIvt3X/ox85I1QoXU reLWTdJG/oEjpHfN6/HMyz3h1Ul9pcgr98yenLcq5nVvhz+zEUoFJKf0nNeJYw7kGDRv p2Rg== X-Gm-Message-State: AJIora/WXJOuDOntlgtpisUcMkAExhxvfpLyEO+EprsKA2vRRExqSDV1 qawoun90DAxaq1zxLiYtztJ0Og== X-Google-Smtp-Source: AGRyM1szrijCIIxZinJ6E7J+5pSN+ES88nSt3CyPGl/JIMkRcNEV5/3s7Tb0OdikxMeqWkjS76rHQg== X-Received: by 2002:a05:6870:709e:b0:10d:752a:9ce7 with SMTP id v30-20020a056870709e00b0010d752a9ce7mr5876067oae.233.1658424501678; Thu, 21 Jul 2022 10:28:21 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id du24-20020a0568703a1800b00101c83352c6sm1106207oab.34.2022.07.21.10.28.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Jul 2022 10:28:21 -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 v3 4/4] selinux: Implement userns_create hook Date: Thu, 21 Jul 2022 12:28:08 -0500 Message-Id: <20220721172808.585539-5-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220721172808.585539-1-fred@cloudflare.com> References: <20220721172808.585539-1-fred@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@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 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 } };