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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: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
This commit is contained in:
Jarkko Sakkinen 2015-10-11 12:26:58 +03:00 committed by Peter Huewe
parent b8e98dcdc5
commit a74f8b3635
1 changed files with 97 additions and 0 deletions
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97
drivers/char/tpm/tpm.h
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@ -1,5 +1,6 @@
/*
* 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;