On Mon, Jun 08, 2015 at 10:39:32PM +0200, Peter Hüwe wrote:
> Hi,
>
>
> Am Mittwoch, 3. Juni 2015, 18:39:14 schrieb Jarkko Sakkinen:
> > This patch introduces struct tpm_buf that provides a string buffer for
> > constructing TPM commands. This allows to construct variable sized TPM
> > commands. This feature is needed for TPM 2.0 commands in order to allow
> > policy authentication and algorithmic agility.
> >
> > The commands in the tpm2-cmd.c have been updated to use struct tpm_buf.
> > Lots of awkward length calculations could be dropped because the buffer
> > knows its length.
> >
> > The code is is along the lines of the string buffer code in
> > security/trusted/trusted.h.
> >
> > Changes since v1:
> >
> > - Fixed potential alignment issues in tpm_buf_tag().
> >
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
>
> > +static inline void tpm_buf_append(struct tpm_buf *buf,
> > + const unsigned char *data,
> > + unsigned int len)
> > +{
> > + struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
> > +
> > + BUG_ON((len + tpm_buf_length(buf)) > TPM_BUF_SIZE);
> > +
> > + memcpy(&buf->data[tpm_buf_length(buf)], data, len);
> > + head->length = cpu_to_be32(tpm_buf_length(buf) + len);
> > +}
> > +
> > +static inline void tpm_buf_store(struct tpm_buf *buf,
> > + unsigned int pos,
> > + const unsigned char *data,
> > + unsigned int len)
> > +{
> > + BUG_ON((pos + len) > TPM_BUF_SIZE);
> > +
> > + memcpy(&buf->data[pos], data, len);
> > +}
>
> Don't you have to update the ->length here?
No. Store is for placing value in position, not appending to the end.
> Thanks,
> Peter
/Jarkko
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