[PATCH v6 02/12] tpm-buf: add handling for TPM2B types

[Jarkko Sakkinen]

On Mon, Sep 09, 2019 at 01:18:35PM +0100, James Bottomley wrote:
> Most complex TPM commands require appending TPM2B buffers to the
> command body.  Since TPM2B types are essentially variable size arrays,
> it makes it impossible to represent these complex command arguments as
> structures and we simply have to build them up using append primitives
> like these.
> 
> Signed-off-by: James Bottomley <James.Bottomley at HansenPartnership.com>

I think a better idea would be to have headerless TPM buffers and also
it makes sense to have a separate length field in the struct to keep the
code sane given that sometimes the buffer does not store the length.

E.g.

enum tpm_buf_flags {
	TPM_BUF_OVERFLOW	= BIT(0),
	TPM_BUF_HEADERLESS	= BIT(1),
};

struct tpm_buf {
	unsigned int length;
	struct page *data_page;
	unsigned int flags;
	u8 *data;
};

/Jarkko