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[209.132.180.67]) by mx.google.com with ESMTP id q1si11044897pgh.396.2019.04.03.17.33.53; Wed, 03 Apr 2019 17:34:07 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b="VagzsV/G"; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726580AbfDDAdB (ORCPT + 99 others); Wed, 3 Apr 2019 20:33:01 -0400 Received: from mail-vk1-f201.google.com ([209.85.221.201]:35219 "EHLO mail-vk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726539AbfDDAdA (ORCPT ); Wed, 3 Apr 2019 20:33:00 -0400 Received: by mail-vk1-f201.google.com with SMTP id z75so446336vkd.2 for ; Wed, 03 Apr 2019 17:33:00 -0700 (PDT) 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=fNnpo8lLzymZARu5UXrve26AL2A88YZO9HZRbBxOnPc=; b=VagzsV/GOtPglfcVAyOphZ6+bVVD4ZbfMzItuKqhvYZLgU1u3KPRVAvlOamt8YnoOJ +8QQ+xK45r5Mvlgk0BL4/GKJmr0qmySeg0i2eBUfDL7DwdH+urAgs6KVu+pEfJoTTPeu UXdF9MlekstBa4MgT33etfSkXxK7il3rlNJ9jyMix+gouqtxYP8gFTmzJG/WA/FBnSfR UhcZZlpWCJLlrRXbC8VoHW4Ne50W8CDKRFmJmmzDXQDXw7C6ZeQK6yOMsbTdkHTDf+TV NuWbl7zBb2C2yPMb5aBB9xEsq+SvqwqeFvT4IHTRujmmhYRMC4FkePtUdXu2HPwjqHcc aUbA== 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=fNnpo8lLzymZARu5UXrve26AL2A88YZO9HZRbBxOnPc=; b=YgV5r8GxjhhztnXCL51AEwnYk67Yb5zsEJNXe2SUdaUbtjyf38b3bNafIUSpeUh7hf jt9syriYLDQUDDiHywYNJ0DsfJw5PZVd1LOYdGkAm0Phrw75QVWAKI0Y1+3pHIiYtwt/ 5d78qU6q0+KWNn9kbC8FqolL+YdwY2lsiA/iZTuptmLdi52OAvBkr2vWjHfyheEpUCuA vTtz0qNCrQdyyvQvHlzs4iEkUszX9k8GsvoRAxdJb7VAjOeFR03EPzVTtziw/4ded+RX NSaBI3rhm6WB4zN/V3RjTRepjaxk86eqDt2y98G/j9df2k9VCFCYpoOVdo+ao6oBxn6l WyRw== X-Gm-Message-State: APjAAAXzNdJmo+uKx+SDBTo1thxWdIod7FNizaQjJU8I1H89VIlBu5Rb /oR/GQ2t7PIaHasaXM6ZUV8mH9ouiX09njaT29sAVg== X-Received: by 2002:ab0:694b:: with SMTP id c11mr415622uas.17.1554337979931; Wed, 03 Apr 2019 17:32:59 -0700 (PDT) Date: Wed, 3 Apr 2019 17:32:24 -0700 In-Reply-To: <20190404003249.14356-1-matthewgarrett@google.com> Message-Id: <20190404003249.14356-3-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190404003249.14356-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [PATCH V32 02/27] 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, linux-api@vger.kernel.org, luto@kernel.org, Matthew Garrett , Jessica Yu 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 Signed-off-by: Matthew Garrett Cc: Jessica Yu --- kernel/module.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 2ad1b5239910..deea9d2763f8 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, LOCKDOWN_INTEGRITY)) + 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) -- 2.21.0.392.gf8f6787159e-goog