| Message ID | 20240102170408.21969-11-James.Bottomley@HansenPartnership.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | add integrity and security to TPM2 transactions | expand |
On Tue Jan 2, 2024 at 7:03 PM EET, James Bottomley wrote: > Replace all instances of &buf.data[TPM_HEADER_SIZE] with a new > function tpm_buf_parameters() because encryption sessions change > where the return parameters are located in the buffer since if a > return session is present they're 4 bytes beyond the header with those > 4 bytes giving the parameter length. If there is no return session, > then they're in the usual place immediately after the header. > > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > > --- > v4: add kdoc > v5: update kdoc add review > --- > drivers/char/tpm/tpm-buf.c | 28 ++++++++++++++++++++++++++++ > include/linux/tpm.h | 2 ++ > 2 files changed, 30 insertions(+) > > diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c > index 32619e9ab4fa..bb81180495d1 100644 > --- a/drivers/char/tpm/tpm-buf.c > +++ b/drivers/char/tpm/tpm-buf.c > @@ -220,3 +220,31 @@ u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset) > return be32_to_cpu(value); > } > EXPORT_SYMBOL_GPL(tpm_buf_read_u32); > + > +static u16 tpm_buf_tag(struct tpm_buf *buf) > +{ > + struct tpm_header *head = (struct tpm_header *)buf->data; > + > + return be16_to_cpu(head->tag); > +} > + > +/** > + * tpm_buf_parameters - return the TPM response parameters area of the tpm_buf > + * @buf: tpm_buf to use > + * > + * Where the parameters are located depends on the tag of a TPM > + * command (it's immediately after the header for TPM_ST_NO_SESSIONS > + * or 4 bytes after for TPM_ST_SESSIONS). Evaluate this and return a > + * pointer to the first byte of the parameters area. > + * > + * @return: pointer to parameters area > + */ > +u8 *tpm_buf_parameters(struct tpm_buf *buf) Not sure about the name but neither have any better suggestion. It will do. > +{ > + int offset = TPM_HEADER_SIZE; > + > + if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS) > + offset += 4; > + > + return &buf->data[offset]; > +} > diff --git a/include/linux/tpm.h b/include/linux/tpm.h > index e8172f81c562..6be263509e81 100644 > --- a/include/linux/tpm.h > +++ b/include/linux/tpm.h > @@ -344,6 +344,8 @@ 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); > > +u8 *tpm_buf_parameters(struct tpm_buf *buf); > + > /* > * Check if TPM device is in the firmware upgrade mode. > */ Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> BR, Jarkko
diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index 32619e9ab4fa..bb81180495d1 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -220,3 +220,31 @@ u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset) return be32_to_cpu(value); } EXPORT_SYMBOL_GPL(tpm_buf_read_u32); + +static u16 tpm_buf_tag(struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + + return be16_to_cpu(head->tag); +} + +/** + * tpm_buf_parameters - return the TPM response parameters area of the tpm_buf + * @buf: tpm_buf to use + * + * Where the parameters are located depends on the tag of a TPM + * command (it's immediately after the header for TPM_ST_NO_SESSIONS + * or 4 bytes after for TPM_ST_SESSIONS). Evaluate this and return a + * pointer to the first byte of the parameters area. + * + * @return: pointer to parameters area + */ +u8 *tpm_buf_parameters(struct tpm_buf *buf) +{ + int offset = TPM_HEADER_SIZE; + + if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS) + offset += 4; + + return &buf->data[offset]; +} diff --git a/include/linux/tpm.h b/include/linux/tpm.h index e8172f81c562..6be263509e81 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -344,6 +344,8 @@ 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); +u8 *tpm_buf_parameters(struct tpm_buf *buf); + /* * Check if TPM device is in the firmware upgrade mode. */