From patchwork Mon Nov 27 17:18:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Djalal Harouni X-Patchwork-Id: 10077647 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id A2609602BC for ; Mon, 27 Nov 2017 17:19:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8448127FA8 for ; Mon, 27 Nov 2017 17:19:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 78E0B2895A; Mon, 27 Nov 2017 17:19:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,FREEMAIL_FROM,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 238B227FA8 for ; Mon, 27 Nov 2017 17:19:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753171AbdK0RTh (ORCPT ); Mon, 27 Nov 2017 12:19:37 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:45560 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932263AbdK0RTW (ORCPT ); Mon, 27 Nov 2017 12:19:22 -0500 Received: by mail-wm0-f65.google.com with SMTP id 9so35661517wme.4; Mon, 27 Nov 2017 09:19:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=XSL+L5EPWRMMfUP8YuGz7oFWd3tU0M0yPScTD8vqSH4=; b=AXw9X9I/6ShQI6uk49qKA8CVkFcEUntqGOv/p4ecIIxyCE6lk5PhIvsGtBGY6n8ld2 6jvwfR4a+W8xbNgsujQOwKQaRqjDtPjRmRBVVXRoy2lwBJjeAjcgVoWEqmv1r5e7KBWC 0OmiszJwB+dPvrsFTeu+ltDZKOTpzrJT8Eq7QNsNCQ+loyzi9x4yhJKxw+SbVoKYL04E P+yMI0NL14Eudh9Ve7w7k4vZ235lp06+/0FjriWcD5U/S3WbWnsbhpSiRSgqn73he+lx ig5mhXNkuWREBfeD4Zc4vJi3/Nu6OslA4wDvZ5zmGFT8KhqsD91kj8KlHlop12jmpIgw +j/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=XSL+L5EPWRMMfUP8YuGz7oFWd3tU0M0yPScTD8vqSH4=; b=eqigeM+Ct5EFVvHct38o5fer0YmHmf+uTW19sdcqtyT+dBIhswRxKtqLATW8A647M1 fm42dolpAxF/1HeGK9cfK0Oo7N4RJHLSSQqOKkMA28yvE7RCQVy/jzoaEJ/+yfrWzw0t h5vY9LVGObK+q8hI8ldTTNtAFsBXGK6K9gB0hJN9AUoa+vIdm6bym/s8xzPIMaPiDIAr 9kbN9pFNqULBrbQf8IXZiKTEPJMlwieP2TfVffbYAy4UhlQ4ilD4dZiCLndOTj/FY+e8 qiwpzbb7plYVYTs/FMgXPfAF0BrCrzE85VyhSQ33n+03k9YtbECuO3H78PXsX5Wqx2EM s6bw== X-Gm-Message-State: AJaThX7omn91svSQSJPjWFjdKoZbq6z8WXM6UDkTnCe/IpUinHWg6GZ7 awvmx/e0KcJpWkionVmD/JU= X-Google-Smtp-Source: AGs4zMaYFOXJssKxhw0ZIjojD5I8tfw6nIIjUxHIaKLZ0XN+3DdSdMiLWbgVyyWEiDkdDIG3BjTwrg== X-Received: by 10.80.174.143 with SMTP id e15mr55154850edd.10.1511803160689; Mon, 27 Nov 2017 09:19:20 -0800 (PST) Received: from localhost.localdomain (ip-109-45-1-111.web.vodafone.de. [109.45.1.111]) by smtp.gmail.com with ESMTPSA id z56sm19356496edb.72.2017.11.27.09.19.18 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 27 Nov 2017 09:19:19 -0800 (PST) From: Djalal Harouni To: Kees Cook , Andy Lutomirski , Andrew Morton , "Luis R. Rodriguez" , James Morris , Ben Hutchings , Solar Designer , Serge Hallyn , Jessica Yu , Rusty Russell , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-hardening@lists.openwall.com Cc: Jonathan Corbet , Ingo Molnar , "David S. Miller" , netdev@vger.kernel.org, Peter Zijlstra , Linus Torvalds , Djalal Harouni Subject: [PATCH v5 next 5/5] net: modules: use request_module_cap() to load 'netdev-%s' modules Date: Mon, 27 Nov 2017 18:18:38 +0100 Message-Id: <1511803118-2552-6-git-send-email-tixxdz@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1511803118-2552-1-git-send-email-tixxdz@gmail.com> References: <1511803118-2552-1-git-send-email-tixxdz@gmail.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP This uses the new request_module_cap() facility to directly propagate CAP_NET_ADMIN capability and the 'netdev' module prefix to the capability subsystem as it was suggested. We do not remove the explicit capable(CAP_NET_ADMIN) check here, but we may remove it in future versions since it is also performed by the capability subsystem. This allows to have a better interface where other subsystems will just use this call and let the capability subsystem handles the permission checks, if the modules should be loaded or not. This is also an infrastructure fix since historically Linux always allowed to auto-load modules without privileges, and later the net code started to check capabilities and prefixes, adapted the CAP_NET_ADMIN check with the 'netdev' prefix to prevent abusing the capability by loading non-netdev modules. However from a bigger picture we want to continue to support automatic module loading as non privileged but also implement easy policy solutions like: User=djalal DenyNewFeatures=no Which will translate to allow the interactive user djalal to load extra Linux features. Others, volatile accounts or guests can be easily blocked from doing so. We have introduced in previous patches the necessary infrastructure and now with this change we start to use the new request_module_cap() function to explicitly tell the capability subsystem that we want to auto-load modules with CAP_NET_ADMIN if they are prefixed. This is also based on suggestions from Rusty Russel and Kees Cook [1] [1] https://lkml.org/lkml/2017/4/26/735 Cc: Ben Hutchings Cc: James Morris Cc: Serge Hallyn Cc: Solar Designer Cc: Andy Lutomirski Suggested-by: Rusty Russell Suggested-by: Kees Cook Signed-off-by: Djalal Harouni --- net/core/dev_ioctl.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c index 7e690d0..fdd8560 100644 --- a/net/core/dev_ioctl.c +++ b/net/core/dev_ioctl.c @@ -382,8 +382,10 @@ void dev_load(struct net *net, const char *name) rcu_read_unlock(); no_module = !dev; + /* "netdev-%s" modules are allowed if CAP_NET_ADMIN is set */ if (no_module && capable(CAP_NET_ADMIN)) - no_module = request_module("netdev-%s", name); + no_module = request_module_cap(CAP_NET_ADMIN, "netdev", + "%s", name); if (no_module && capable(CAP_SYS_MODULE)) request_module("%s", name); }