From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA9C7C43381 for ; Wed, 6 Mar 2019 23:59:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6F4A20663 for ; Wed, 6 Mar 2019 23:59:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="BRJHSCTT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726281AbfCFX7b (ORCPT ); Wed, 6 Mar 2019 18:59:31 -0500 Received: from mail-pf1-f202.google.com ([209.85.210.202]:33992 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726186AbfCFX72 (ORCPT ); Wed, 6 Mar 2019 18:59:28 -0500 Received: by mail-pf1-f202.google.com with SMTP id f18so15457953pfd.1 for ; Wed, 06 Mar 2019 15:59:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=on0K5RsXZCuQ1MSHm3bzRhjjZRQoobIGEx9Qfo8mw4g=; b=BRJHSCTT5HXLhMtX9ZhNlkKo0cDQm7AcgfOZcUu0aVzbksY2LE+NzHcIcivLi8bvmr QVIr11Kz9ZMgAarXVz8pGyLrX4PgOilfxs+OxOumql0mEeSGAhZTIitLv+vpyA9FsDxR PkXbU8I/n23+DS+uuWh190cNWlx2abMh6wXCuXn5ib5BLnreSIOVpRc6d6TEdFfLjXnd Mc3scLQdBEsEUyRSZMkV9pl3zGQtDXrZ84RTwmtCCwU9Vnm+wltQA/Plox9G5aTc4g7R 66+o6J0+C+fCe9Ez6FZ/Vk481nzH2qjQrrLzVyjGya50CvNhzziWyreF85q2LAMcEgby dowA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=on0K5RsXZCuQ1MSHm3bzRhjjZRQoobIGEx9Qfo8mw4g=; b=KaliZv8/DWngaHyI6hZ4SvqSmigkr7IdfTttvJ2vXE4lITWyFjv8RQwGaNrPVb5S1U s0eCOkOdVTGu9dJJzpv+evxZIC9PMY/ESas181wxhcTxSOgvUcqf9U+Z4IjVsKNESVV4 X85/HenA44cpewMHvJ2L7q1FlqhB3S25GHOByDDpRO+y4e/tgYjSd9+hCN4KDCR7nfkl FePgTyi0maktxqUMHrLMeIY0C14DljJwJC14m1LJCoDZ6ltBgdhUZG5RhQDslgfe/gtP LcLalA7Ee1AW43hOCvQEsHKtVAgaC5YWa6GDHreMd7UCE4yKwfl5892Pws8TbKiIdkNO vIKg== X-Gm-Message-State: APjAAAVf7bev/NocetRiagg3Y259hXzp7Mj3FOdiRiemU7qaRLGlUz79 07u1XM+G+Z+P8YBqccWrplp+BMA4e3/K0wfvVEvytw== X-Google-Smtp-Source: APXvYqxcWasyCCaYPhVYEfqiCvDF53otXQ/MyvgFH2qxeaaDZ8tzGek3/QhJs6plqMr+BqfthgxyQUs9xtWbIXvMXd0J2A== X-Received: by 2002:a62:5206:: with SMTP id g6mr3844743pfb.58.1551916767462; Wed, 06 Mar 2019 15:59:27 -0800 (PST) Date: Wed, 6 Mar 2019 15:58:49 -0800 In-Reply-To: <20190306235913.6631-1-matthewgarrett@google.com> Message-Id: <20190306235913.6631-4-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190306235913.6631-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.352.gf09ad66450-goog Subject: [PATCH 03/27] Enforce module signatures if the kernel is locked down From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells If the kernel is locked down, require that all modules have valid signatures that we can verify. I have adjusted the errors generated: (1) If there's no signature (ENODATA) or we can't check it (ENOPKG, ENOKEY), then: (a) If signatures are enforced then EKEYREJECTED is returned. (b) If there's no signature or we can't check it, but the kernel is locked down then EPERM is returned (this is then consistent with other lockdown cases). (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we return the error we got. Note that the X.509 code doesn't check for key expiry as the RTC might not be valid or might not have been transferred to the kernel's clock yet. [Modified by Matthew Garrett to remove the IMA integration. This will be replaced with integration with the IMA architecture policy patchset.] Signed-off-by: David Howells Reviewed-by: Jiri Bohac cc: "Lee, Chun-Yi" cc: James Morris Signed-off-by: Matthew Garrett --- kernel/module.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 2ad1b5239910..9a377c6ea200 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2767,8 +2767,9 @@ static inline void kmemleak_load_module(const struct module *mod, #ifdef CONFIG_MODULE_SIG static int module_sig_check(struct load_info *info, int flags) { - int err = -ENOKEY; + int err = -ENODATA; const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const char *reason; const void *mod = info->hdr; /* @@ -2783,16 +2784,40 @@ static int module_sig_check(struct load_info *info, int flags) err = mod_verify_sig(mod, info); } - if (!err) { + switch (err) { + case 0: info->sig_ok = true; return 0; - } - /* Not having a signature is only an error if we're strict. */ - if (err == -ENOKEY && !is_module_sig_enforced()) - err = 0; + /* We don't permit modules to be loaded into trusted kernels + * without a valid signature on them, but if we're not + * enforcing, certain errors are non-fatal. + */ + case -ENODATA: + reason = "Loading of unsigned module"; + goto decide; + case -ENOPKG: + reason = "Loading of module with unsupported crypto"; + goto decide; + case -ENOKEY: + reason = "Loading of module with unavailable key"; + decide: + if (is_module_sig_enforced()) { + pr_notice("%s is rejected\n", reason); + return -EKEYREJECTED; + } - return err; + if (kernel_is_locked_down(reason)) + return -EPERM; + return 0; + + /* All other errors are fatal, including nomem, unparseable + * signatures and signature check failures - even if signatures + * aren't required. + */ + default: + return err; + } } #else /* !CONFIG_MODULE_SIG */ static int module_sig_check(struct load_info *info, int flags) -- 2.21.0.352.gf09ad66450-goog