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: 12943803 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 6D949C00140 for ; Mon, 15 Aug 2022 16:21:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233196AbiHOQVi (ORCPT ); Mon, 15 Aug 2022 12:21:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232888AbiHOQUq (ORCPT ); Mon, 15 Aug 2022 12:20:46 -0400 Received: from mail-ot1-x329.google.com (mail-ot1-x329.google.com [IPv6:2607:f8b0:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD86313CE0 for ; Mon, 15 Aug 2022 09:20:42 -0700 (PDT) Received: by mail-ot1-x329.google.com with SMTP id o15-20020a9d718f000000b00638c1348012so748907otj.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=cgXy+fcYYgp2JGyQLoMLd6a9pxdFvqwpXf+ud5z7uaBLQRfBD13wRiqcxpSa2iA0WW cTDhu5QXz6tUZ0wehbfNmJb8M8kzzcMwcxwROodf1d5zwEQuKSHGrhtQJo7FEKSf4okH r/EAkjDFfH80hG7KCZU20QE5yTHy2gvgUOBxjbDOdUjHhOrhkGGLYLtjGFnZIZJnHPkz lh8q1myqr/VeSVXThY14ZwqylEZOpcsG0pb7npQosQQ+VLKQhi7lUpwU9L61kfM3me0s tbVzDtpnKMKS3lnOoljh+FXcsA/n+yOX0o1CnImz82ETePl7+Gebi7B7AR0z99z0EQTc DcrQ== X-Gm-Message-State: ACgBeo1R4C5de14kNzyUeDPmIXOcXfTwRzdv/OpNeiZoXFjHVmiL1eiw g/SQTkYTpwokT12xxOtPaiRkuQ== 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: 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 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 } };