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tpm: tpm1: rewrite tpm1_get_random() using tpm_buf structure

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1. Use tpm_buf in tpm1_get_random()
2. Fix comment in tpm_get_random() so it is clear that
the function is expected to return number of random bytes.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Tomas Winkler 2018-10-19 21:23:02 +03:00 committed by Jarkko Sakkinen
parent c22780ff0c
commit 7aee9c52d7
3 changed files with 48 additions and 47 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
drivers/char/tpm/tpm-interface.c
View file

@ -600,7 +600,7 @@ EXPORT_SYMBOL_GPL(tpm_pm_resume);
* @out: destination buffer for the random bytes
* @max: the max number of bytes to write to @out
*
* Return: same as with tpm_transmit_cmd()
* Return: number of random bytes read or a negative error value.
*/
int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max)
{

11
drivers/char/tpm/tpm.h
View file

@ -396,20 +396,9 @@ struct tpm_pcrread_in {
* compiler warnings about stack frame size. */
#define TPM_MAX_RNG_DATA 128
struct tpm_getrandom_out {
__be32 rng_data_len;
u8 rng_data[TPM_MAX_RNG_DATA];
} __packed;
struct tpm_getrandom_in {
__be32 num_bytes;
} __packed;
typedef union {
struct tpm_pcrread_in pcrread_in;
struct tpm_pcrread_out pcrread_out;
struct tpm_getrandom_in getrandom_in;
struct tpm_getrandom_out getrandom_out;
} tpm_cmd_params;
struct tpm_cmd_t {

82
drivers/char/tpm/tpm1-cmd.c
View file

@ -505,58 +505,70 @@ ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
EXPORT_SYMBOL_GPL(tpm1_getcap);
#define TPM_ORD_GET_RANDOM 70
#define TPM_GETRANDOM_RESULT_SIZE 18
static const struct tpm_input_header tpm_getrandom_header = {
.tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
.length = cpu_to_be32(14),
.ordinal = cpu_to_be32(TPM_ORD_GET_RANDOM)
};
struct tpm1_get_random_out {
__be32 rng_data_len;
u8 rng_data[TPM_MAX_RNG_DATA];
} __packed;
int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max)
/**
* tpm1_get_random() - get random bytes from the TPM's RNG
* @chip: a &struct tpm_chip instance
* @dest: destination buffer for the random bytes
* @max: the maximum number of bytes to write to @dest
*
* Return:
* * number of bytes read
* * -errno or a TPM return code otherwise
*/
int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
{
struct tpm_cmd_t tpm_cmd;
u32 recd;
struct tpm1_get_random_out *out;
u32 num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA);
u32 rlength;
int err, total = 0, retries = 5;
u8 *dest = out;
struct tpm_buf buf;
u32 total = 0;
int retries = 5;
u32 recd;
int rc;
if (!out || !num_bytes || max > TPM_MAX_RNG_DATA)
return -EINVAL;
rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
if (rc)
return rc;
do {
tpm_cmd.header.in = tpm_getrandom_header;
tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
tpm_buf_append_u32(&buf, num_bytes);
err = tpm_transmit_cmd(chip, NULL, &tpm_cmd,
TPM_GETRANDOM_RESULT_SIZE + num_bytes,
offsetof(struct tpm_getrandom_out,
rng_data),
0, "attempting get random");
if (err)
break;
rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE,
sizeof(out->rng_data_len), 0,
"attempting get random");
if (rc)
goto out;
recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE];
recd = be32_to_cpu(out->rng_data_len);
if (recd > num_bytes) {
total = -EFAULT;
break;
rc = -EFAULT;
goto out;
}
rlength = be32_to_cpu(tpm_cmd.header.out.length);
if (rlength < TPM_HEADER_SIZE +
offsetof(struct tpm_getrandom_out, rng_data) +
recd) {
total = -EFAULT;
break;
if (tpm_buf_length(&buf) < TPM_HEADER_SIZE +
sizeof(out->rng_data_len) + recd) {
rc = -EFAULT;
goto out;
}
memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);
memcpy(dest, out->rng_data, recd);
dest += recd;
total += recd;
num_bytes -= recd;
} while (retries-- && (size_t)total < max);
return total ? total : -EIO;
tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
} while (retries-- && total < max);
rc = total ? (int)total : -EIO;
out:
tpm_buf_destroy(&buf);
return rc;
}
#define TPM_ORDINAL_PCRREAD 21