From patchwork Tue Nov 21 22:31:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13463715 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C18B35B20A for ; Tue, 21 Nov 2023 22:32:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pPa6/htb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E93FC433C7; Tue, 21 Nov 2023 22:32:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700605928; bh=7Pxyt/ojqGnO8r8ulwYL+5aIat96EW0XQ6GmCI/E80I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pPa6/htb4/rLBsJ6Rp45h/Hbaup9UGgWxCyHmai5sAi2SbxnYPNVo+oZ2pO1MfHeI N87V278AiSMf4ULfCirRV0e5uuPzLLcUTkW/umfUlweQolYUsHccsNLSP8gHtnUv+u rpqhHxrb/idIUJbKv76O0PpkEitZaTOFeix9X7b5M7ZzVhcq5hXxrahLiM1/4Dsuyc bIx0v0sJzgdn5rhrsxp68ICAhwThP3HYb6or4QHcrpze6UU2HqaLdfHShMB55AwPaN oA9mt2b5qYQcX8GRvgU5OHD2gxgiujHvlEk0xX5LhOGZZp78QzO8daLRulOz6Wn824 FnDqO6cDIvOpA== From: Jarkko Sakkinen To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , Peter Huewe , Jason Gunthorpe , James Bottomley , Julien Gomes , Jerry Snitselaar , Mario Limonciello Subject: [PATCH v5 7/8] tpm: Add tpm_buf_read_{u8,u16,u32} Date: Wed, 22 Nov 2023 00:31:19 +0200 Message-ID: <20231121223130.30824-8-jarkko@kernel.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231121223130.30824-1-jarkko@kernel.org> References: <20231121223130.30824-1-jarkko@kernel.org> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 --- 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-c71398422fa1@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..f0b122a1c2d9 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; if ((buf->length + new_length) > PAGE_SIZE) { - WARN(1, "tpm_buf: overflow\n"); + WARN(1, "tpm_buf: write overflow\n"); buf->flags |= 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 = *offset + count; + if (next_offset >= buf->length) { + WARN(1, "tpm_buf: read out of boundary\n"); + buf->flags |= TPM_BUF_BOUNDARY_ERROR; + return; + } + + memcpy(output, &buf->data[*offset], count); + *offset = 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 = BIT(0), /* TPM2B format: */ TPM_BUF_TPM2B = BIT(1), + /* read out of boundary: */ + TPM_BUF_BOUNDARY_ERROR = BIT(2), }; /* @@ -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); /* * Check if TPM device is in the firmware upgrade mode.