[PATCH] tpm: fix type issues in tpm_getcap()

From: Jarkko Sakkinen
Date: Wed Feb 01 2017 - 12:54:06 EST


There are two type issues associated with tpm_getcap().

You must not do arithmetic with __be32 or __le32 types because sometimes
it results incorrect results. Calculations must be done only with data
that is in CPU byte order. This commit migrates tpm_getcap() to struct
tpm_buf in order to sort out these issues.

The second issue is with struct cap_t as the size of the type bool is
assumed to be one byte. This commit sorts out the issue by changing the
type to u8.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
v2:
- Use struct tpm_buf.
- Merge the type change of 'owned' to this patch.
drivers/char/tpm/tpm-interface.c | 33 ++++++++++++++++++---------------
drivers/char/tpm/tpm.h | 15 +--------------
2 files changed, 19 insertions(+), 29 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 423938e..7af1e8c 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -480,31 +480,34 @@ 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, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
- min_cap_length, 0, desc);
+
+ rc = tpm_transmit_cmd(chip, buf.data, PAGE_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 bff37be..709e7d4 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -281,7 +281,7 @@ struct permanent_flags_t {
typedef union {
struct permanent_flags_t perm_flags;
struct stclear_flags_t stclear_flags;
- bool owned;
+ u8 owned;
__be32 num_pcrs;
struct tpm_version_t tpm_version;
struct tpm_version_1_2_t tpm_version_1_2;
@@ -307,17 +307,6 @@ 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];
@@ -367,10 +356,8 @@ 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;
--
2.9.3