tpm: fix byte order related arithmetic inconsistency in tpm_getcap()

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>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 4ed08ab..be54159 100644 (file)
--- 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, 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 e81d8c7..dd11734 100644 (file)
--- 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;