Re: [tpmdd-devel] [PATCH RFC 2/2] tpm: refactor tpm2_get_tpm_pt to tpm2_getcap_cmd

From: Jarkko Sakkinen
Date: Fri Nov 11 2016 - 19:03:12 EST


On Fri, Nov 11, 2016 at 09:51:45AM +0530, Nayna wrote:
>
>
> On 10/09/2016 03:44 PM, Jarkko Sakkinen wrote:
> > Refactored tpm2_get_tpm_pt to tpm2_getcap_cmd, which means that it also
> > takes capability ID as input. This is required to access
> > TPM_CAP_HANDLES, which contains metadata needed for swapping transient
> > data.
> >
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> > ---
> > drivers/char/tpm/tpm.h | 6 +++-
> > drivers/char/tpm/tpm2-cmd.c | 64 ++++++++++++++++++++---------------------
> > drivers/char/tpm/tpm_tis_core.c | 3 +-
> > 3 files changed, 38 insertions(+), 35 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> > index 0fab6d5..8176f42 100644
> > --- a/drivers/char/tpm/tpm.h
> > +++ b/drivers/char/tpm/tpm.h
> > @@ -85,6 +85,10 @@ enum tpm2_capabilities {
> > TPM2_CAP_TPM_PROPERTIES = 6,
> > };
> >
> > +enum tpm2_properties {
> > + TPM2_PT_FAMILY_INDICATOR = 0x100,
> > +};
> > +
> > enum tpm2_startup_types {
> > TPM2_SU_CLEAR = 0x0000,
> > TPM2_SU_STATE = 0x0001,
> > @@ -485,7 +489,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
> > int tpm2_unseal_trusted(struct tpm_chip *chip,
> > struct trusted_key_payload *payload,
> > struct trusted_key_options *options);
> > -ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,
> > +ssize_t tpm2_getcap_cmd(struct tpm_chip *chip, u32 cap_id, u32 property_id,
> > u32 *value, const char *desc);
> >
> > int tpm2_auto_startup(struct tpm_chip *chip);
> > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> > index 2900e18..fcf3d86 100644
> > --- a/drivers/char/tpm/tpm2-cmd.c
> > +++ b/drivers/char/tpm/tpm2-cmd.c
> > @@ -111,13 +111,13 @@ struct tpm2_pcr_extend_in {
> > u8 digest[TPM_DIGEST_SIZE];
> > } __packed;
> >
> > -struct tpm2_get_tpm_pt_in {
> > +struct tpm2_getcap_in {
> > __be32 cap_id;
> > __be32 property_id;
> > __be32 property_cnt;
> > } __packed;
> >
> > -struct tpm2_get_tpm_pt_out {
> > +struct tpm2_getcap_out {
> > u8 more_data;
> > __be32 subcap_id;
> > __be32 property_cnt;
> > @@ -140,8 +140,8 @@ union tpm2_cmd_params {
> > struct tpm2_pcr_read_in pcrread_in;
> > struct tpm2_pcr_read_out pcrread_out;
> > struct tpm2_pcr_extend_in pcrextend_in;
> > - struct tpm2_get_tpm_pt_in get_tpm_pt_in;
> > - struct tpm2_get_tpm_pt_out get_tpm_pt_out;
> > + struct tpm2_getcap_in getcap_in;
> > + struct tpm2_getcap_out getcap_out;
> > struct tpm2_get_random_in getrandom_in;
> > struct tpm2_get_random_out getrandom_out;
> > };
> > @@ -435,16 +435,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
> > return total ? total : -EIO;
> > }
> >
> > -#define TPM2_GET_TPM_PT_IN_SIZE \
> > - (sizeof(struct tpm_input_header) + \
> > - sizeof(struct tpm2_get_tpm_pt_in))
> > -
> > -static const struct tpm_input_header tpm2_get_tpm_pt_header = {
> > - .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> > - .length = cpu_to_be32(TPM2_GET_TPM_PT_IN_SIZE),
> > - .ordinal = cpu_to_be32(TPM2_CC_GET_CAPABILITY)
> > -};
> > -
> > /**
> > * Append TPMS_AUTH_COMMAND to the buffer. The buffer must be allocated with
> > * tpm_buf_alloc().
> > @@ -750,35 +740,43 @@ out:
> > return rc;
> > }
> >
> > +#define TPM2_GETCAP_IN_SIZE \
> > + (sizeof(struct tpm_input_header) + sizeof(struct tpm2_getcap_in))
> > +
> > +static const struct tpm_input_header tpm2_getcap_header = {
> > + .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> > + .length = cpu_to_be32(TPM2_GETCAP_IN_SIZE),
> > + .ordinal = cpu_to_be32(TPM2_CC_GET_CAPABILITY)
> > +};
> > +
> > /**
> > - * tpm2_get_tpm_pt() - get value of a TPM_CAP_TPM_PROPERTIES type property
> > - * @chip: TPM chip to use.
> > - * @property_id: property ID.
> > - * @value: output variable.
> > + * tpm2_getcap_cmd() - execute a TPM2_GetCapability command
> > + * @chip: TPM chip to use
> > + * @cap_id: capability ID
> > + * @property_id: property ID
> > + * @value: value of the property
> > * @desc: passed to tpm_transmit_cmd()
> > *
> > - * 0 is returned when the operation is successful. If a negative number is
> > - * returned it remarks a POSIX error code. If a positive number is returned
> > - * it remarks a TPM error.
> > + * Return: same as with tpm_transmit_cmd
> > */
> > -ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id, u32 *value,
> > - const char *desc)
> > +ssize_t tpm2_getcap_cmd(struct tpm_chip *chip, u32 cap_id, u32 property_id,
> > + u32 *value, const char *desc)
>
> This function currently returns single value "u32 *value" as output data.
>
> Some calling function expect list of values from capabilities output.
> For eg., get_active_banks() use TPM_CAP_PCRS capability to retrieve list of
> active banks. And this capability returns array of pcr selections(which is a
> struct representing each active PCR bank)
>
> I was thinking, can we define output parameter as struct of cap_id and union
> of expected cap_data ?

Unless you have major concerns about performance, which I think are not
relevant here, calling this in a loop is perfectly adequate and a lot of
simpler than having a generic version (with moreData handling and
everything).

I would rather see uses of struct cap_t to shrink than to expand. The
same goes for other horrific unions that exist today in the driver.

/Jarkko