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Subject[PATCH] tpm: fix byte order related arithmetic inconsistency in tpm_getcap()
Date
You should not do arithmetic with __be32 or __le32 types because
sometimes it results incorrect results. Calculations must be done only
with integers that are in in the CPU byte order. This commit migrates
tpm_getcap() to struct tpm_buf in order to sort out these issues.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
Now this should work as Robertos patches move byte order conversion
where it should be. Sadly I'm out of reach to my Dell E6400 laptop
that I use for TPM 1.2 testing.
drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
drivers/char/tpm/tpm.h | 13 -------------
2 files changed, 16 insertions(+), 27 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 4ed08ab4d2a8..7436422458c7 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -552,31 +552,33 @@ static const struct tpm_input_header tpm_getcap_header = {
ssize_t tpm_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
const char *desc, size_t min_cap_length)
{
- struct tpm_cmd_t tpm_cmd;
+ struct tpm_buf buf;
int rc;

- tpm_cmd.header.in = tpm_getcap_header;
+ rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
+ if (rc)
+ return rc;
+
if (subcap_id == TPM_CAP_VERSION_1_1 ||
subcap_id == TPM_CAP_VERSION_1_2) {
- tpm_cmd.params.getcap_in.cap = cpu_to_be32(subcap_id);
- /*subcap field not necessary */
- tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(0);
- tpm_cmd.header.in.length -= cpu_to_be32(sizeof(__be32));
+ tpm_buf_append_u32(&buf, subcap_id);
+ tpm_buf_append_u32(&buf, 0);
} else {
if (subcap_id == TPM_CAP_FLAG_PERM ||
subcap_id == TPM_CAP_FLAG_VOL)
- tpm_cmd.params.getcap_in.cap =
- cpu_to_be32(TPM_CAP_FLAG);
+ tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
else
- tpm_cmd.params.getcap_in.cap =
- cpu_to_be32(TPM_CAP_PROP);
- tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
- tpm_cmd.params.getcap_in.subcap = cpu_to_be32(subcap_id);
+ tpm_buf_append_u32(&buf, TPM_CAP_PROP);
+
+ tpm_buf_append_u32(&buf, 4);
+ tpm_buf_append_u32(&buf, subcap_id);
}
- rc = tpm_transmit_cmd(chip, NULL, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
+ rc = tpm_transmit_cmd(chip, NULL, buf.data, TPM_INTERNAL_RESULT_SIZE,
min_cap_length, 0, desc);
if (!rc)
- *cap = tpm_cmd.params.getcap_out.cap;
+ *cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
+
+ tpm_buf_destroy(&buf);
return rc;
}
EXPORT_SYMBOL_GPL(tpm_getcap);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index e81d8c7acb39..dd1173427fb2 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -339,17 +339,6 @@ enum tpm_sub_capabilities {
TPM_CAP_PROP_TIS_DURATION = 0x120,
};

-struct tpm_getcap_params_in {
- __be32 cap;
- __be32 subcap_size;
- __be32 subcap;
-} __packed;
-
-struct tpm_getcap_params_out {
- __be32 cap_size;
- cap_t cap;
-} __packed;
-
struct tpm_readpubek_params_out {
u8 algorithm[4];
u8 encscheme[2];
@@ -399,10 +388,8 @@ struct tpm_startup_in {
} __packed;

typedef union {
- struct tpm_getcap_params_out getcap_out;
struct tpm_readpubek_params_out readpubek_out;
u8 readpubek_out_buffer[sizeof(struct tpm_readpubek_params_out)];
- struct tpm_getcap_params_in getcap_in;
struct tpm_pcrread_in pcrread_in;
struct tpm_pcrread_out pcrread_out;
struct tpm_pcrextend_in pcrextend_in;
--
2.11.0
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