tpm: Store the length of the tpm_buf data separately.

[linux-2.6-block.git] / drivers / char / tpm / tpm-buf.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Handling of TPM command and other buffers.
 */

#include <linux/tpm_command.h>
#include <linux/module.h>
#include <linux/tpm.h>

/**
 * tpm_buf_init() - Allocate and initialize a TPM command
 * @buf:	A &tpm_buf
 * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
 * @ordinal:	A command ordinal
 *
 * Return: 0 or -ENOMEM
 */
int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
{
	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
	if (!buf->data)
		return -ENOMEM;

	tpm_buf_reset(buf, tag, ordinal);
	return 0;
}
EXPORT_SYMBOL_GPL(tpm_buf_init);

/**
 * tpm_buf_reset() - Initialize a TPM command
 * @buf:	A &tpm_buf
 * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
 * @ordinal:	A command ordinal
 */
void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
{
	struct tpm_header *head = (struct tpm_header *)buf->data;

	WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS &&
		tag != TPM2_ST_SESSIONS && tag != 0);

	buf->flags = 0;
	buf->length = sizeof(*head);
	head->tag = cpu_to_be16(tag);
	head->length = cpu_to_be32(sizeof(*head));
	head->ordinal = cpu_to_be32(ordinal);
}
EXPORT_SYMBOL_GPL(tpm_buf_reset);

void tpm_buf_destroy(struct tpm_buf *buf)
{
	free_page((unsigned long)buf->data);
}
EXPORT_SYMBOL_GPL(tpm_buf_destroy);

/**
 * tpm_buf_length() - Return the number of bytes consumed by the data
 * @buf:	A &tpm_buf
 *
 * Return: The number of bytes consumed by the buffer
 */
u32 tpm_buf_length(struct tpm_buf *buf)
{
	return buf->length;
}
EXPORT_SYMBOL_GPL(tpm_buf_length);

/**
 * tpm_buf_append() - Append data to an initialized buffer
 * @buf:	A &tpm_buf
 * @new_data:	A data blob
 * @new_length:	Size of the appended data
 */
void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
{
	struct tpm_header *head = (struct tpm_header *)buf->data;

	/* Return silently if overflow has already happened. */
	if (buf->flags & TPM_BUF_OVERFLOW)
		return;

	if ((buf->length + new_length) > PAGE_SIZE) {
		WARN(1, "tpm_buf: overflow\n");
		buf->flags |= TPM_BUF_OVERFLOW;
		return;
	}

	memcpy(&buf->data[buf->length], new_data, new_length);
	buf->length += new_length;
	head->length = cpu_to_be32(buf->length);
}
EXPORT_SYMBOL_GPL(tpm_buf_append);

void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)
{
	tpm_buf_append(buf, &value, 1);
}
EXPORT_SYMBOL_GPL(tpm_buf_append_u8);

void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value)
{
	__be16 value2 = cpu_to_be16(value);

	tpm_buf_append(buf, (u8 *)&value2, 2);
}
EXPORT_SYMBOL_GPL(tpm_buf_append_u16);

void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
{
	__be32 value2 = cpu_to_be32(value);

	tpm_buf_append(buf, (u8 *)&value2, 4);
}
EXPORT_SYMBOL_GPL(tpm_buf_append_u32);