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tpm: Add tpm_buf_read_{u8,u16,u32}

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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: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This commit is contained in:
Jarkko Sakkinen 2024-04-29 16:27:56 -04:00
parent d926ee92e8
commit acd5eb4f50
2 changed files with 83 additions and 1 deletions
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79
drivers/char/tpm/tpm-buf.c
View file

@ -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);

5
include/linux/tpm.h
View file

@ -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.