[PATCH v3 17/20] tpm1: implement tpm1_pcr_read_dev() using tpm_buf structure

[Tomas Winkler]

Implement tpm1_pcr_read_dev() using tpm_buf and remove
now unneeded structures from tpm.h

Signed-off-by: Tomas Winkler <tomas.wink...@intel.com>
---
V3: new in the series
 drivers/char/tpm/tpm.h      | 18 ++----------------
 drivers/char/tpm/tpm1-cmd.c | 38 +++++++++++++++++++++-----------------
 2 files changed, 23 insertions(+), 33 deletions(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index d6eca81a011a..d0402aa122ec 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -382,13 +382,10 @@ typedef union {
        struct  tpm_output_header out;
 } tpm_cmd_header;
 
-struct tpm_pcrread_out {
-       u8      pcr_result[TPM_DIGEST_SIZE];
+struct tpm_cmd_t {
+       tpm_cmd_header  header;
 } __packed;
 
-struct tpm_pcrread_in {
-       __be32  pcr_idx;
-} __packed;
 
 /* 128 bytes is an arbitrary cap. This could be as large as TPM_BUFSIZE - 18
  * bytes, but 128 is still a relatively large number of random bytes and
@@ -396,17 +393,6 @@ struct tpm_pcrread_in {
  * compiler warnings about stack frame size. */
 #define TPM_MAX_RNG_DATA       128
 
-typedef union {
-       struct  tpm_pcrread_in  pcrread_in;
-       struct  tpm_pcrread_out pcrread_out;
-} tpm_cmd_params;
-
-struct tpm_cmd_t {
-       tpm_cmd_header  header;
-       tpm_cmd_params  params;
-} __packed;
-
-
 /* A string buffer type for constructing TPM commands. This is based on the
  * ideas of string buffer code in security/keys/trusted.h but is heap based
  * in order to keep the stack usage minimal.
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 5708d4bf908f..e81641f9d0e3 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -574,29 +574,33 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, 
size_t max)
        return rc;
 }
 
-#define TPM_ORDINAL_PCRREAD 21
-#define READ_PCR_RESULT_SIZE 30
-#define READ_PCR_RESULT_BODY_SIZE 20
-static const struct tpm_input_header pcrread_header = {
-       .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
-       .length = cpu_to_be32(14),
-       .ordinal = cpu_to_be32(TPM_ORDINAL_PCRREAD)
-};
-
+#define TPM_ORD_PCRREAD 21
 int tpm1_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
 {
+       struct tpm_buf buf;
        int rc;
-       struct tpm_cmd_t cmd;
 
-       cmd.header.in = pcrread_header;
-       cmd.params.pcrread_in.pcr_idx = cpu_to_be32(pcr_idx);
-       rc = tpm_transmit_cmd(chip, NULL, &cmd, READ_PCR_RESULT_SIZE,
-                             READ_PCR_RESULT_BODY_SIZE, 0,
+       rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
+       if (rc)
+               return rc;
+
+       tpm_buf_append_u32(&buf, pcr_idx);
+
+       rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE,
+                             TPM_DIGEST_SIZE, 0,
                              "attempting to read a pcr value");
+       if (rc)
+               goto out;
 
-       if (rc == 0)
-               memcpy(res_buf, cmd.params.pcrread_out.pcr_result,
-                      TPM_DIGEST_SIZE);
+       if (tpm_buf_length(&buf) < TPM_DIGEST_SIZE) {
+               rc = -EFAULT;
+               goto out;
+       }
+
+       memcpy(res_buf, &buf.data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
+
+out:
+       tpm_buf_destroy(&buf);
        return rc;
 }
 
-- 
2.14.4