From patchwork Mon Aug 15 16:20:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12943808 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 9BA75C00140 for ; Mon, 15 Aug 2022 16:21:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232884AbiHOQVe (ORCPT ); Mon, 15 Aug 2022 12:21:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232887AbiHOQUq (ORCPT ); Mon, 15 Aug 2022 12:20:46 -0400 Received: from mail-ot1-x32a.google.com (mail-ot1-x32a.google.com [IPv6:2607:f8b0:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD8B91EEE1 for ; Mon, 15 Aug 2022 09:20:42 -0700 (PDT) Received: by mail-ot1-x32a.google.com with SMTP id o15-20020a9d718f000000b00638c1348012so748908otj.2 for ; Mon, 15 Aug 2022 09:20:42 -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=U3OK8Oqnf2K0vdWXT1jn4LVlcHC3Qy4QXRttGxzPtuo=; b=XU3mICcICTtNu7uN8K5AA/UUF9eGokgmjP4mS51xOSo4TbR6mIgICfjf3JleWSCsnD 3bKxTlmLlhl3CdsgdqLQhB63ngHK/3WAjkc9apGYatsqocuIO2tLcXn8aGkf/AKiaTLs sTT1sq/iMyXBWFfe2c4PBoNmB/mESTtAqL4LQ= 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=U3OK8Oqnf2K0vdWXT1jn4LVlcHC3Qy4QXRttGxzPtuo=; b=T59BACSprFMr50UV/0uqJzwUZBM0UFlkFNw/XI8fYzHAro2ibXLCqXuE0U2Zk8Hfwl 783MgkTawSeu8NaqAkqL9DKeIx9JhT+VWNiHmbkRN8jxXbGkFQJscne+k4jAfFI6A5OK T7d1gJUD8fxEkJu4CWBlemWL9so5ZUWDyvxo0P5WSfPL1NbIHCfsdqxW0lP5ple8RWfW 3XyqkXZKoWhH9NHpPB/MoXMv7Q/SFLYQ1g/Joi1xKN4Qn696da7CTKOrfO1FtV6QU3xw Nnd/D1wpPzBKJwim3ZyXP2bADk1VyKt5tF/kSRnUW74Xl+DorauhTQgFpwdv6h5aGFv7 Jpxg== X-Gm-Message-State: ACgBeo2GVpgkz1AhGhctwjV2DUVx6n7x/I1FowSREYiWpb1t8y9xIsx/ phYNIfbL6FAJGGerBz+6fMLoGg== X-Google-Smtp-Source: AA6agR4zqUyCOz7UeYx3gb/1BVfk3brb7qMNS9yuuT17I/dl5o+tdGlomKfd9D9Qo+BAH1l8rlRK4A== X-Received: by 2002:a05:6830:10c9:b0:636:d88f:1299 with SMTP id z9-20020a05683010c900b00636d88f1299mr6217405oto.134.1660580441763; Mon, 15 Aug 2022 09:20:41 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id x91-20020a9d37e4000000b00636ee04e7aesm2163371otb.67.2022.08.15.09.20.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Aug 2022 09:20:41 -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, tixxdz@gmail.com, Frederick Lawler Subject: [PATCH v5 4/4] selinux: Implement userns_create hook Date: Mon, 15 Aug 2022 11:20:28 -0500 Message-Id: <20220815162028.926858-5-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220815162028.926858-1-fred@cloudflare.com> References: <20220815162028.926858-1-fred@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: 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 v4: - None 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 79573504783b..b9f1078450b3 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -4221,6 +4221,14 @@ 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) @@ -7111,6 +7119,7 @@ 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 } };