From patchwork Tue Feb 13 17:13:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 13555419 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AED015FDC7; Tue, 13 Feb 2024 17:21:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=96.44.175.130 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707844875; cv=none; b=qOu817BezdwCak4TLfdos2zRAjKFf8N662omcSCSSrB9zVJQvnYN1w1ZSEAJa/sa8Xs06F/D9/3BNtX+6XIYxujE/M9ohXLg8b9ldTWl74BoOYomiNfsvvVKNA5uDUuTlGNsVcnnujqZohAJOTZCL6N1RGH7mkHDlhljXLyKg/w= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707844875; c=relaxed/simple; bh=BkLyBAyuRrKe9xAril8jS648H4kvAAKXrIJmeVCqvzA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=US4SQ5294QS49IwQpoGbsZnCqiMdKkMk061hQx59wwyJlJPNweUqkvkOfeyDxWk+Z/2EU7N3Q8235Ycndt6yeyGNybxea19Ag7tIwKuQDbzT2rHT0cz3AWqhxtt1xEoQmal6Ywb/PcuBfar0OmZqRHMvN5CiYejOW+uFkktH/aI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=KujFkC23; arc=none smtp.client-ip=96.44.175.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="KujFkC23" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1707844872; bh=BkLyBAyuRrKe9xAril8jS648H4kvAAKXrIJmeVCqvzA=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References:From; b=KujFkC2339FSGH5rIznqGD2dTrmXguIyvkfj0oGd4i4GuVkM8kB/CBWw/nEwjeGgM C4o5aQlP4VzVvangXQFVeghrhUXXvjT+HwtVLeyCwVe2Aqr0OnLtzV/3HiqEPqdznC e3/PgA+CJ7qQ2h6uy/qB89sk1aEBQW9m+1JdBCmU= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id EBC991280D89; Tue, 13 Feb 2024 12:21:12 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavis, port 10024) with ESMTP id wybY5_HqMma7; Tue, 13 Feb 2024 12:21:12 -0500 (EST) Received: from lingrow.int.hansenpartnership.com (unknown [153.66.160.227]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 14C631280CB7; Tue, 13 Feb 2024 12:21:12 -0500 (EST) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , keyrings@vger.kernel.org, Ard Biesheuvel Subject: [PATCH v7 16/21] tpm: add hmac checks to tpm2_pcr_extend() Date: Tue, 13 Feb 2024 12:13:29 -0500 Message-Id: <20240213171334.30479-17-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20240213171334.30479-1-James.Bottomley@HansenPartnership.com> References: <20240213171334.30479-1-James.Bottomley@HansenPartnership.com> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 tpm2_pcr_extend() is used by trusted keys to extend a PCR to prevent a key from being re-loaded until the next reboot. To use this functionality securely, that extend must be protected by a session hmac. This patch adds HMAC protection so tampering with the tpm2_pcr_extend() command in flight is detected. Signed-off-by: James Bottomley Reviewed-by: Jarkko Sakkinen --- v7: add review --- drivers/char/tpm/tpm2-cmd.c | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index b0e72fb563d9..a53a843294ed 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -216,13 +216,6 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx, return rc; } -struct tpm2_null_auth_area { - __be32 handle; - __be16 nonce_size; - u8 attributes; - __be16 auth_size; -} __packed; - /** * tpm2_pcr_extend() - extend a PCR value * @@ -236,24 +229,22 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, struct tpm_digest *digests) { struct tpm_buf buf; - struct tpm2_null_auth_area auth_area; int rc; int i; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + rc = tpm2_start_auth_session(chip); if (rc) return rc; - tpm_buf_append_u32(&buf, pcr_idx); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + if (rc) { + tpm2_end_auth_session(chip); + return rc; + } - auth_area.handle = cpu_to_be32(TPM2_RS_PW); - auth_area.nonce_size = 0; - auth_area.attributes = 0; - auth_area.auth_size = 0; + tpm_buf_append_name(chip, &buf, pcr_idx, NULL); + tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0); - tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area)); - tpm_buf_append(&buf, (const unsigned char *)&auth_area, - sizeof(auth_area)); tpm_buf_append_u32(&buf, chip->nr_allocated_banks); for (i = 0; i < chip->nr_allocated_banks; i++) { @@ -262,7 +253,9 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, chip->allocated_banks[i].digest_size); } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); tpm_buf_destroy(&buf);