Commit acd5eb4f authored by Jarkko Sakkinen's avatar Jarkko Sakkinen
Browse files

tpm: Add tpm_buf_read_{u8,u16,u32} 



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: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Reviewed-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Tested-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
parent d926ee92

drivers/char/tpm/tpm-buf.c

+78 −1
Original line number Diff line number Diff line
@@ -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 +144,80 @@ 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);

include/linux/tpm.h

+5 −0
Original line number Diff line number Diff line
@@ -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.