Re: [PATCH v4 2/2] tpm: vtpm_proxy: Implement request_locality function.

[Stefan Berger]

On 05/15/2017 08:41 AM, Jarkko Sakkinen wrote:
On Wed, May 10, 2017 at 07:54:22PM -0400, Stefan Berger wrote:
Implement the request_locality function. To set the locality on the
backend we define vendor-specific TPM 1.2 and TPM 2 ordinals and send
a command to the backend to set the locality for the next commands.
Signed-off-by: Stefan Berger <stef...@linux.vnet.ibm.com>
---
  drivers/char/tpm/tpm.h            |  1 +
  drivers/char/tpm/tpm_vtpm_proxy.c | 34 ++++++++++++++++++++++++++++++++++
  include/uapi/linux/vtpm_proxy.h   |  5 +++++
  3 files changed, 40 insertions(+)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 4b4c8de..10f0467 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -527,6 +527,7 @@ enum tpm_transmit_flags {
        TPM_TRANSMIT_UNLOCKED   = BIT(0),
  };
  
+ssize_t tpm_transfer(struct tpm_chip *chip, u8 *buf, u32 count, size_t bufsiz);
  ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
                     u8 *buf, size_t bufsiz, unsigned int flags);
  ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c 
b/drivers/char/tpm/tpm_vtpm_proxy.c
index 751059d..374c4ff 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -371,6 +371,39 @@ static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  
*chip, u8 status)
        return ret;
  }
  
+static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
+{
+       struct tpm_buf buf;
+       int rc;
+       const struct tpm_output_header *header;
+
+       if (chip->flags & TPM_CHIP_FLAG_TPM2)
+               rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
+                                 TPM2_CC_SET_LOCALITY);
+       else
+               rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND,
+                                 TPM_ORD_SET_LOCALITY);
+       if (rc)
+               return rc;
+       tpm_buf_append_u8(&buf, locality);
+
+       rc = tpm_transfer(chip, buf.data, tpm_buf_length(&buf), PAGE_SIZE);
+       if (rc < 0) {
+               locality = rc;
+               goto out;
+       }
+
+       header = (const struct tpm_output_header *)buf.data;
+       rc = be32_to_cpu(header->return_code);
+       if (rc)
+               locality = -1;
+
+out:
+       tpm_buf_destroy(&buf);
+
+       return locality;
+}
+
  static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
        .flags = TPM_OPS_AUTO_STARTUP,
        .recv = vtpm_proxy_tpm_op_recv,
@@ -380,6 +413,7 @@ static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
        .req_complete_mask = VTPM_PROXY_REQ_COMPLETE_FLAG,
        .req_complete_val = VTPM_PROXY_REQ_COMPLETE_FLAG,
        .req_canceled = vtpm_proxy_tpm_req_canceled,
+       .request_locality = vtpm_proxy_request_locality,
  };
  
  /*
diff --git a/include/uapi/linux/vtpm_proxy.h b/include/uapi/linux/vtpm_proxy.h
index a69e991..6b91c2c 100644
--- a/include/uapi/linux/vtpm_proxy.h
+++ b/include/uapi/linux/vtpm_proxy.h
@@ -46,4 +46,9 @@ struct vtpm_proxy_new_dev {
  
  #define VTPM_PROXY_IOC_NEW_DEV	_IOWR(0xa1, 0x00, struct vtpm_proxy_new_dev)
  
+/* vendor specific commands to set locality */
+#define TPM2_CC_SET_LOCALITY   0x20001000
+#define TPM_ORD_SET_LOCALITY   0x20001000
+
+
  #endif /* _UAPI_LINUX_VTPM_PROXY_H */
--
2.4.3
This is a question.

Did you have some kind of big idea with 0x20? I was just thinking
that one way to do this would to allocate starting from 0xFFFFFFFF.

Not quite. Per TPM 1.2 and TPM 2 specs we should operate here with 
Vendor specific commands and they are identified by bit 29.

Check section 17 'Ordinals': 
https://trustedcomputinggroup.org/wp-content/uploads/TPM-Main-Part-2-TPM-Structures_v1.2_rev116_01032011.pdf

Check section 8.9 TPMA_CC: 
https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-2-Structures-01.38.pdf

If anything was the 'big idea' then it was the offset '0x1000' :-)

   Stefan