From patchwork Wed Mar 6 23:58:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 10842067 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4133A1515 for ; Thu, 7 Mar 2019 00:01:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2E64A2E9F5 for ; Thu, 7 Mar 2019 00:01:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 22FC22EA0E; Thu, 7 Mar 2019 00:01:52 +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=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=ham 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 AD94F2E9F5 for ; Thu, 7 Mar 2019 00:01:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726297AbfCFX73 (ORCPT ); Wed, 6 Mar 2019 18:59:29 -0500 Received: from mail-pf1-f201.google.com ([209.85.210.201]:36427 "EHLO mail-pf1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726134AbfCFX72 (ORCPT ); Wed, 6 Mar 2019 18:59:28 -0500 Received: by mail-pf1-f201.google.com with SMTP id w16so15441639pfn.3 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=fRb5C4vGQ+SxyGIKWKi4+3ez8FNPR2saztXu3Ea2kxJSdrs/KEmSGTtJoVE2xIicD4 d/+u0je3ddfG8aya87kDyOhdTwHVcVma7yjv5h0e/OO/quWeosBxfsT+pgDguNxSZqV5 5g9KZBwQlhj4OdhMtni3Y402t5m+IElwhHxC89J61ExlvDVdm+EIPFf0AicSudW9x4ln KewYsSern4/SoVtZ+dc2YNlKBkoHSNDZ4lVco/7Nl31RfyRcgSjLeiTqdxsHXP3PPI6l g15l0Llg9M7hHVilbbA0vV8RTfN2sZDTaDsOPYnRYJTOWKDp0ZHGduXjl15iVAswveT+ krAA== X-Gm-Message-State: APjAAAWXK7XaLHVh37szVgmdoX7U6BkH6D+2x/K5+xkTNUsXV2Lf5R94 BerS2dfc7v+apJ59lmj54ZO0ZcOcRhnGbyX3o6qBkw== 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 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP 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)