From patchwork Mon Sep 9 12:24:27 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 11137851 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A437676 for ; Mon, 9 Sep 2019 12:24:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7883D2081B for ; Mon, 9 Sep 2019 12:24:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="R6DfaewI"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="R6DfaewI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726540AbfIIMYa (ORCPT ); Mon, 9 Sep 2019 08:24:30 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:48406 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726282AbfIIMYa (ORCPT ); Mon, 9 Sep 2019 08:24:30 -0400 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 5D1688EE180; Mon, 9 Sep 2019 05:24:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1568031870; bh=AVrjyvgb3krMB/HHAo2SNQxEzajsFtqw/mMBv/svl58=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=R6DfaewIXfs6Dm5D2QWcGedUmfaxHjkTlJXUNgZ9OvV4wzV3FQtlp36osHsyX8+A3 3IaGS4yQaDlUC68vP+3jtoQ/kz2/EZrNo+z47EqALykUtbEldsDFXziJxHMKYlHfzM mByh8KVIp4NnQazjyhKagJUw++axfwSssiF9kWW8= Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id EM2wXG0MAh1B; Mon, 9 Sep 2019 05:24:30 -0700 (PDT) Received: from [192.168.6.117] (unknown [148.69.85.38]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 2586C8EE105; Mon, 9 Sep 2019 05:24:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1568031870; bh=AVrjyvgb3krMB/HHAo2SNQxEzajsFtqw/mMBv/svl58=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=R6DfaewIXfs6Dm5D2QWcGedUmfaxHjkTlJXUNgZ9OvV4wzV3FQtlp36osHsyX8+A3 3IaGS4yQaDlUC68vP+3jtoQ/kz2/EZrNo+z47EqALykUtbEldsDFXziJxHMKYlHfzM mByh8KVIp4NnQazjyhKagJUw++axfwSssiF9kWW8= Message-ID: <1568031867.6613.39.camel@HansenPartnership.com> Subject: [PATCH v6 10/12] tpm: add the null key name as a tpm2 sysfs variable From: James Bottomley To: linux-integrity@vger.kernel.org Cc: linux-crypto@vger.kernel.org, linux-security-module@vger.kernel.org, Jarkko Sakkinen Date: Mon, 09 Sep 2019 13:24:27 +0100 In-Reply-To: <1568031408.6613.29.camel@HansenPartnership.com> References: <1568031408.6613.29.camel@HansenPartnership.com> X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: This is the last component of encrypted tpm2 session handling that allows us to verify from userspace that the key derived from the NULL seed genuinely belongs to the TPM and has not been spoofed. The procedure for doing this involves creating an attestation identity key (which requires verification of the TPM EK certificate) and then using that AIK to sign a certification of the Elliptic Curve key over the NULL seed. Userspace must create this EC Key using the parameters prescribed in TCG TPM v2.0 Provisioning Guidance for the SRK ECC; if this is done correctly the names will match and the TPM can then run a TPM2_Certify operation on this derived primary key using the newly created AIK. Signed-off-by: James Bottomley --- drivers/char/tpm/tpm-sysfs.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c index d9caedda075b..07aa8f427b96 100644 --- a/drivers/char/tpm/tpm-sysfs.c +++ b/drivers/char/tpm/tpm-sysfs.c @@ -309,6 +309,19 @@ static ssize_t timeouts_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(timeouts); +static ssize_t null_name_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct tpm_chip *chip = to_tpm_chip(dev); + int size = TPM2_NAME_SIZE; + + bin2hex(buf, chip->tpmkeyname, size); + size *= 2; + buf[size++] = '\n'; + return size; +} +static DEVICE_ATTR_RO(null_name); + static struct attribute *tpm_dev_attrs[] = { &dev_attr_pubek.attr, &dev_attr_pcrs.attr, @@ -323,17 +336,29 @@ static struct attribute *tpm_dev_attrs[] = { NULL, }; +static struct attribute *tpm2_dev_attrs[] = { + &dev_attr_null_name.attr, + NULL, +}; + static const struct attribute_group tpm_dev_group = { .attrs = tpm_dev_attrs, }; +static const struct attribute_group tpm2_dev_group = { + .attrs = tpm2_dev_attrs, +}; + void tpm_sysfs_add_device(struct tpm_chip *chip) { /* XXX: If you wish to remove this restriction, you must first update * tpm_sysfs to explicitly lock chip->ops. */ - if (chip->flags & TPM_CHIP_FLAG_TPM2) + if (chip->flags & TPM_CHIP_FLAG_TPM2) { + WARN_ON(chip->groups_cnt != 0); + chip->groups[chip->groups_cnt++] = &tpm2_dev_group; return; + } /* The sysfs routines rely on an implicit tpm_try_get_ops, device_del * is called before ops is null'd and the sysfs core synchronizes this