Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a74f8b36 authored by Jarkko Sakkinen's avatar Jarkko Sakkinen Committed by Peter Huewe
Browse files

tpm: introduce tpm_buf 



This patch introduces struct tpm_buf that provides a string buffer for
constructing TPM commands. This allows to construct variable sized TPM
commands. For the buffer a page is allocated and mapped, which limits
maximum size to PAGE_SIZE.

Variable sized TPM commands are needed in order to add algorithmic
agility.

Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: default avatarPeter Huewe <peterhuewe@gmx.de>
Signed-off-by: default avatarPeter Huewe <peterhuewe@gmx.de>
parent b8e98dcd

drivers/char/tpm/tpm.h

+97 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2004 IBM Corporation

 * Copyright (C) 2015 Intel Corporation

 *

 * Authors:

 * Leendert van Doorn <leendert@watson.ibm.com>
@@ -28,6 +29,7 @@ 
#include <linux/tpm.h>

#include <linux/acpi.h>

#include <linux/cdev.h>

#include <linux/highmem.h>



enum tpm_const {

	TPM_MINOR = 224,	/* officially assigned */
@@ -390,6 +392,101 @@ struct tpm_cmd_t { 
	tpm_cmd_params	params;

} __packed;



/* A string buffer type for constructing TPM commands. This is based on the

 * ideas of string buffer code in security/keys/trusted.h but is heap based

 * in order to keep the stack usage minimal.

 */



enum tpm_buf_flags {

	TPM_BUF_OVERFLOW	= BIT(0),

};



struct tpm_buf {

	struct page *data_page;

	unsigned int flags;

	u8 *data;

};



static inline void tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)

{

	struct tpm_input_header *head;



	buf->data_page = alloc_page(GFP_HIGHUSER);

	if (!buf->data_page)

		return -ENOMEM;



	buf->flags = 0;

	buf->data = kmap(buf->data_page);



	head = (struct tpm_input_header *) buf->data;



	head->tag = cpu_to_be16(tag);

	head->length = cpu_to_be32(sizeof(*head));

	head->ordinal = cpu_to_be32(ordinal);



	return 0;

}



static inline void tpm_buf_destroy(struct tpm_buf *buf)

{

	kunmap(buf->data_page);

	__free_page(buf->data_page);

}



static inline u32 tpm_buf_length(struct tpm_buf *buf)

{

	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;



	return be32_to_cpu(head->length);

}



static inline u16 tpm_buf_tag(struct tpm_buf *buf)

{

	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;



	return be16_to_cpu(head->tag);

}



static inline void tpm_buf_append(struct tpm_buf *buf,

				  const unsigned char *new_data,

				  unsigned int new_len)

{

	struct tpm_input_header *head = (struct tpm_input_header *) buf->data;

	u32 len = tpm_buf_length(buf);



	/* Return silently if overflow has already happened. */

	if (buf->flags & TPM_BUF_OVERFLOW)

		return;



	if ((len + new_len) > PAGE_SIZE) {

		WARN(1, "tpm_buf: overflow\n");

		buf->flags |= TPM_BUF_OVERFLOW;

		return;

	}



	memcpy(&buf->data[len], new_data, new_len);

	head->length = cpu_to_be32(len + new_len);

}



static inline void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)

{

	tpm_buf_append(buf, &value, 1);

}



static inline 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);

}



static inline 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);

}



extern struct class *tpm_class;

extern dev_t tpm_devt;

extern const struct file_operations tpm_fops;