From patchwork Tue Nov 21 21:17:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13463604 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 3DBA154666 for ; Tue, 21 Nov 2023 21:17:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lKkdUPzG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC746C433C9; Tue, 21 Nov 2023 21:17:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700601466; bh=tjk9p4TlrYObLmQhm2Bz2gDnKhOQJKBounykc75pSc0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lKkdUPzGcA/FX4eFo4XJ2ND71Ux3fNopFK7OjOAiSVvDrNsMUkos0j/xde29hbHCw aeixhlrdHLlXricAz/WxMJ2ZXG3cLapgCvKj1xsjb71H2Ix82m7Je3mJkA09rkn0VZ BaFDcORFIm7Pd9UiNpwJX58/LRxuPh5+JTw7iZ3LJTGf5qmrecLYGbPceiMpMire9o RBSnV4Gfkxq6ia/+S2Lw9I5ic0tUWv3okfozOgURGmQZR5LZqj5XLHfpK7biYXw+SH EJhZ8MvtXnZ03tA2EiWU3sccvoVkp7OrMqzEolCXhNn9maRf4u07r9CV+85qk3excP Q47c2aCVZ4g7Q== 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 , Peter Huewe , James Bottomley , Paul Moore , James Morris , "Serge E. Hallyn" , Julien Gomes Subject: [PATCH v4 7/8] tpm: Add tpm_buf_read_{u8,u16,u32} Date: Tue, 21 Nov 2023 23:17:16 +0200 Message-ID: <20231121211717.31681-8-jarkko@kernel.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231121211717.31681-1-jarkko@kernel.org> References: <20231121211717.31681-1-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 --- 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 | 76 +++++++++++++++++++++++++++++++++++++- include/linux/tpm.h | 5 +++ 2 files changed, 80 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index 12bfade11372..f721e90757c4 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -108,7 +108,7 @@ 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; } @@ -144,3 +144,77 @@ 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) +{ + /* Return silently if overflow has already happened. */ + if (buf->flags & TPM_BUF_BOUNDARY_ERROR) + return; + + if (*(offset + count) >= 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 += count; +} + +/** + * 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.