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

[Nayna]

On 11/15/2016 05:18 AM, Jarkko Sakkinen wrote:

On Fri, Nov 11, 2016 at 04:02:43PM -0800, Jarkko Sakkinen wrote:

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.sakki...@linux.intel.com>
---
   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.

If you are fine with this patch (give Reviewed-by) I can apply this
and add to my 4.10 pull request so that we have common baseline to
develop both event log and the resource manager.

This is a very low risk commit to take to 4.10 because it is only used
for interrupt generation in the TIS driver at the moment.

Works for capabilities with more_data(yes) and single value properties.

Reviewed-by: Nayna Jain <na...@linux.vnet.ibm.com>

Thanks & Regards,
  - Nayna

/Jarkko