From patchwork Tue Nov 6 15:01:59 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 10670705 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 DE4AC17D4 for ; Tue, 6 Nov 2018 15:07:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D02E12A4B3 for ; Tue, 6 Nov 2018 15:07:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C44BA2A4F9; Tue, 6 Nov 2018 15:07:53 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI 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 664402A4B3 for ; Tue, 6 Nov 2018 15:07:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729728AbeKGAdb (ORCPT ); Tue, 6 Nov 2018 19:33:31 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:32720 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729574AbeKGAda (ORCPT ); Tue, 6 Nov 2018 19:33:30 -0500 Received: from LHREML712-CAH.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id 5C5F51837C5A4; Tue, 6 Nov 2018 15:07:49 +0000 (GMT) Received: from roberto-HP-EliteDesk-800-G2-DM-65W.huawei.com (10.204.65.153) by smtpsuk.huawei.com (10.201.108.35) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 6 Nov 2018 15:07:40 +0000 From: Roberto Sassu To: , CC: , , , , Roberto Sassu Subject: [PATCH v4 6/6] tpm: ensure that the output of PCR read contains the correct digest size Date: Tue, 6 Nov 2018 16:01:59 +0100 Message-ID: <20181106150159.1136-7-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181106150159.1136-1-roberto.sassu@huawei.com> References: <20181106150159.1136-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.65.153] X-CFilter-Loop: Reflected Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP This patch protects against data corruption that could happen in the bus, by checking that that the digest size returned by the TPM during a PCR read matches the size of the algorithm passed as argument to tpm2_pcr_read(). This check is performed after information about the PCR banks has been retrieved. Signed-off-by: Roberto Sassu Reviewed-by: Jarkko Sakkinen --- drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index e2d5b84286a7..3b0b5b032901 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out { int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, struct tpm_digest *digest_struct, u16 *digest_size_ptr) { + int i; int rc; struct tpm_buf buf; struct tpm2_pcr_read_out *out; u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0}; u16 digest_size; + u16 expected_digest_size = 0; if (pcr_idx >= TPM2_PLATFORM_PCR) return -EINVAL; + if (!digest_size_ptr) { + for (i = 0; i < chip->nr_active_banks && + chip->active_banks[i].alg_id != digest_struct->alg_id; i++) + ; + + if (i == chip->nr_active_banks) + return -EINVAL; + + expected_digest_size = chip->active_banks[i].digest_size; + } + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ); if (rc) return rc; @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE]; digest_size = be16_to_cpu(out->digest_size); - if (digest_size > sizeof(digest_struct->digest)) { + if (digest_size > sizeof(digest_struct->digest) || + (!digest_size_ptr && digest_size != expected_digest_size)) { rc = -EINVAL; goto out; }