From nobody Wed Dec 17 17:23:00 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E295C61D97 for ; Fri, 24 Nov 2023 02:03:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231375AbjKXCDe (ORCPT ); Thu, 23 Nov 2023 21:03:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232787AbjKXCDL (ORCPT ); Thu, 23 Nov 2023 21:03:11 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E53E19AC for ; Thu, 23 Nov 2023 18:03:03 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2814C433C9; Fri, 24 Nov 2023 02:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700791383; bh=QxqRnwnwf/AxgHt8+bTTK2G02f45I3yxIt0Ytvx6QdM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ASsI15mdzvCNaBq5rXvzB4Nd8ICJz7E0gaH/EKZ7qXU0hKbX9KxWNVfTyjj3iC4O4 qHgMbd8RubYG5DwMKrwY9kiYVH2AEKZDbOdxBQCNQHKV1fD44zIdRb3KvXVFz/iPYn B2vgDQDEpOABh7Nr48fy1cCXLW2foYinIXr0TlNzhHrtf9yGcLAITvXdyq8g2d7o6p INqwlQ0HmxqYZ/ejCwWiXjnD157iNb1tjazhGrjid1Fz7Hk6oywNYHhREWftqcu8Fa u+YglqCEaHbmU2uh6MwkJyd2A36J8WpgAO0cLdY+p27iAPDS0N4g+zDC+eJzpbbAiW nvvfZkmyLW9+g== From: Jarkko Sakkinen To: linux-integrity@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jarkko Sakkinen , James Bottomley , William Roberts , Stefan Berger , David Howells , Jason Gunthorpe , Mimi Zohar , Mario Limonciello , Jerry Snitselaar Subject: [PATCH v6 7/8] tpm: Add tpm_buf_read_{u8,u16,u32} Date: Fri, 24 Nov 2023 04:02:36 +0200 Message-ID: <20231124020237.27116-8-jarkko@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124020237.27116-1-jarkko@kernel.org> References: <20231124020237.27116-1-jarkko@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Declare reader functions for the instances of struct tpm_buf. If the read goes out of boundary, TPM_BUF_BOUNDARY_ERROR is set, and subsequent read will do nothing. Signed-off-by: Jarkko Sakkinen Reviewed-by: Stefan Berger --- v5 [2023-11-24]: Fixed off-by-one error in the boundary check. v4 [2023-11-21]: Address James Bottomley's feedback for v2 of this patch, i.e. offset pointer was not correctly dereferenced. v3 [2023-11-21]: Add possibility to check for boundary error to the as response to the feedback from Mario Limenciello: https://lore.kernel.org/linux-integrity/3f9086f6-935f-48a7-889b-c71398422fa= 1@amd.com/ --- drivers/char/tpm/tpm-buf.c | 79 +++++++++++++++++++++++++++++++++++++- include/linux/tpm.h | 5 +++ 2 files changed, 83 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index 099b4a56c5d5..32619e9ab4fa 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -107,7 +107,7 @@ void tpm_buf_append(struct tpm_buf *buf, const u8 *new_= data, u16 new_length) return; =20 if ((buf->length + new_length) > PAGE_SIZE) { - WARN(1, "tpm_buf: overflow\n"); + WARN(1, "tpm_buf: write overflow\n"); buf->flags |=3D TPM_BUF_OVERFLOW; return; } @@ -143,3 +143,80 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32= value) tpm_buf_append(buf, (u8 *)&value2, 4); } EXPORT_SYMBOL_GPL(tpm_buf_append_u32); + +/** + * tpm_buf_read() - Read from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * @count: the number of bytes to read + * @output: the output buffer + */ +static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count,= void *output) +{ + off_t next_offset; + + /* Return silently if overflow has already happened. */ + if (buf->flags & TPM_BUF_BOUNDARY_ERROR) + return; + + next_offset =3D *offset + count; + if (next_offset > buf->length) { + WARN(1, "tpm_buf: read out of boundary\n"); + buf->flags |=3D TPM_BUF_BOUNDARY_ERROR; + return; + } + + memcpy(output, &buf->data[*offset], count); + *offset =3D next_offset; +} + +/** + * tpm_buf_read_u8() - Read 8-bit word from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * + * Return: next 8-bit word + */ +u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset) +{ + u8 value; + + tpm_buf_read(buf, offset, sizeof(value), &value); + + return value; +} +EXPORT_SYMBOL_GPL(tpm_buf_read_u8); + +/** + * tpm_buf_read_u16() - Read 16-bit word from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * + * Return: next 16-bit word + */ +u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset) +{ + u16 value; + + tpm_buf_read(buf, offset, sizeof(value), &value); + + return be16_to_cpu(value); +} +EXPORT_SYMBOL_GPL(tpm_buf_read_u16); + +/** + * tpm_buf_read_u32() - Read 32-bit word from a TPM buffer + * @buf: &tpm_buf instance + * @offset: offset within the buffer + * + * Return: next 32-bit word + */ +u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset) +{ + u32 value; + + tpm_buf_read(buf, offset, sizeof(value), &value); + + return be32_to_cpu(value); +} +EXPORT_SYMBOL_GPL(tpm_buf_read_u32); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 715db4a91c1f..e8172f81c562 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -302,6 +302,8 @@ enum tpm_buf_flags { TPM_BUF_OVERFLOW =3D BIT(0), /* TPM2B format: */ TPM_BUF_TPM2B =3D BIT(1), + /* read out of boundary: */ + TPM_BUF_BOUNDARY_ERROR =3D BIT(2), }; =20 /* @@ -338,6 +340,9 @@ void tpm_buf_append(struct tpm_buf *buf, const u8 *new_= data, u16 new_length); void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value); void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value); void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value); +u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset); +u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset); +u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset); =20 /* * Check if TPM device is in the firmware upgrade mode. --=20 2.43.0