From patchwork Thu Jul 7 22:32:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12910336 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 D919BCCA479 for ; Thu, 7 Jul 2022 22:33:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237076AbiGGWdT (ORCPT ); Thu, 7 Jul 2022 18:33:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237077AbiGGWcw (ORCPT ); Thu, 7 Jul 2022 18:32:52 -0400 Received: from mail-ot1-x335.google.com (mail-ot1-x335.google.com [IPv6:2607:f8b0:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E75E9675B5 for ; Thu, 7 Jul 2022 15:32:45 -0700 (PDT) Received: by mail-ot1-x335.google.com with SMTP id by10-20020a056830608a00b0061c1ac80e1dso1941202otb.13 for ; Thu, 07 Jul 2022 15:32:45 -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=gpnGP72y7AlRDZxLLIIKCxGjGB4QqIYx1EtuBERrAGY=; b=KfAsVex69jTCIdg5XmbRjXWWWy/S0Tca6CS8SwDAmazdBPIoDnrCREhbjrLFevHaGt 6ufFk77dMvGWeRIVQPkT2IDgHAiRo2457GzNSRpAj0LvK9u6HolMJoALdrhWiSJY3cDP lupYF3+zn3pi6FeorsgnBUBjJN6/6EstmhD80= 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=gpnGP72y7AlRDZxLLIIKCxGjGB4QqIYx1EtuBERrAGY=; b=2QcfHYdWhMuJ5rGWV1YTL7ht5JgZldvsrzO4owx3erK/z8Ftcocd6mE7dzIvyWTRiP AZigJCo+Cz7E+Qiljw6iLe0DFkvo4joU3KLRJiTbsyzuX4vOoQzCdkKqERZJDXM+xyLd zPswTfLuyb6VMljQBd6MCyQxsarcUQFvlqeLgwVWnLxlBNhf1kvuX+jkZA29ub3uTmkZ m3pBthD2fgoHnx48zzu/4fFZ+GxHxdj+1hQdwjPrmWqvVsDiJ07NdOb7CHtUpU101Vnz X9v5IPc+KkA27S9g42E/24+0WSaa4OtkyH1GE6aUcUmCry/G2i7AI1Fz5n3VvQWl6pYs l1GA== X-Gm-Message-State: AJIora+vAEYMyf3s+RwAUIbmThkzJ8mdvAlYnja0eidXmMCmmxmvsHH8 GS/XefOL5Z8F2mfoUJhtKvE4Ww== X-Google-Smtp-Source: AGRyM1sGIyzyI1rIE0sIpG00vgHQmsRFAehgN6hwD9szVgsHUkRW2ie4sEb+YtA6SNwdPP9ZDtc8qw== X-Received: by 2002:a9d:4c0e:0:b0:616:dd87:cb91 with SMTP id l14-20020a9d4c0e000000b00616dd87cb91mr182367otf.185.1657233164958; Thu, 07 Jul 2022 15:32:44 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id i16-20020a05683033f000b00616b835f5e7sm16246222otu.43.2022.07.07.15.32.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Jul 2022 15:32:43 -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, Frederick Lawler Subject: [PATCH v2 4/4] selinux: Implement create_user_ns hook Date: Thu, 7 Jul 2022 17:32:28 -0500 Message-Id: <20220707223228.1940249-5-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220707223228.1940249-1-fred@cloudflare.com> References: <20220707223228.1940249-1-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 namespace { userns_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 domB_t : namespace { userns_create }; Signed-off-by: Frederick Lawler --- 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..73fbcb434fe0 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_NAMESPACE, + NAMESPACE__USERNS_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(create_user_ns, 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..9943e85c6b3e 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 } }, + { "namespace", + { "userns_create", NULL } }, { NULL } };