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: 12933958 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 416F2C00144 for ; Mon, 1 Aug 2022 18:03:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234303AbiHASD0 (ORCPT ); Mon, 1 Aug 2022 14:03:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234285AbiHASCx (ORCPT ); Mon, 1 Aug 2022 14:02:53 -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 AC4D22613F for ; Mon, 1 Aug 2022 11:02:25 -0700 (PDT) Received: by mail-oi1-x233.google.com with SMTP id w72so9597580oiw.6 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=R9JZ96YUjkZ67TtrxyoNp9MIBIhn+rvR7a+FT57IcIptMNK6u4Mbwg1S7K3SupTKo1 lOXV5aj7djM4fN7yLUNcxaI1uKm8HcwAbX1lxhfd6oea/dOPkGJImI1G7yYPbCd6mdua 01V8Y60futSOUbu9n/37miSsH/decWTTXFfANrkReF+0aC+4g5/1sLFg+z3CMUz+1tWw 5wz+Ox97fhB40nqlKf3h74JwQuaIeCeDmoROt6o3WnNmYgDo2v3Tb8ffrKI+0JxFm/7+ X0vCBDv1hMtYVuFNORa+K5M0qI0PbnD3KlMCdmJI9GAXo47TunpMVoiA+ZhnRZPHGv2x hERQ== X-Gm-Message-State: AJIora/ZwPrg7u7Ru3xcLLv14L39soYuLiHo3GJEtMxFzkP9W2Alinbh yVdrbzH7X5MLtIXxhjJsAf3Clg== 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: 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 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 } };