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Subject[PATCH v3 17/20] tpm1: implement tpm1_pcr_read_dev() using tpm_buf structure
Date
Implement tpm1_pcr_read_dev() using tpm_buf and remove
now unneeded structures from tpm.h

Signed-off-by: Tomas Winkler <tomas.winkler@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
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