Re: [PATCH 5/5] tpm: migrate tpm2_get_random() to use struct tpm_buf

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On Wed, Feb 28, 2018 at 09:58:18PM +0200, Jarkko Sakkinen wrote:
> In order to make struct tpm_buf the first class object for constructing
> TPM commands, migrate tpm2_get_random() to use it. In addition, removed
> remaining references to struct tpm2_cmd. All of them use it to acquire
> the length of the response, which can be achieved by using
> tpm_buf_length().
> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> ---
>  drivers/char/tpm/tpm.h      |  2 +-
>  drivers/char/tpm/tpm2-cmd.c | 87 ++++++++++++++++-----------------------------
>  2 files changed, 31 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index cccd5994a0e1..cffb71ec0289 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -557,7 +557,7 @@ static inline u32 tpm2_rc_value(u32 rc)
>  int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
>  int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
>  		    struct tpm2_digest *digests);
> -int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max);
> +int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max);
>  void tpm2_flush_context_cmd(struct tpm_chip *chip, u32 handle,
>  			    unsigned int flags);
>  int tpm2_seal_trusted(struct tpm_chip *chip,
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 43791947b8e1..574caa33aab3 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -27,25 +27,6 @@ enum tpm2_session_attributes {
>  	TPM2_SA_CONTINUE_SESSION	= BIT(0),
>  };
>  
> -struct tpm2_get_random_in {
> -	__be16	size;
> -} __packed;
> -
> -struct tpm2_get_random_out {
> -	__be16	size;
> -	u8	buffer[TPM_MAX_RNG_DATA];
> -} __packed;
> -
> -union tpm2_cmd_params {
> -	struct	tpm2_get_random_in	getrandom_in;
> -	struct	tpm2_get_random_out	getrandom_out;
> -};
> -
> -struct tpm2_cmd {
> -	tpm_cmd_header		header;
> -	union tpm2_cmd_params	params;
> -} __packed;
> -
>  struct tpm2_hash {
>  	unsigned int crypto_id;
>  	unsigned int tpm_id;
> @@ -298,62 +279,58 @@ int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
>  }
>  
>  
> -#define TPM2_GETRANDOM_IN_SIZE \
> -	(sizeof(struct tpm_input_header) + \
> -	 sizeof(struct tpm2_get_random_in))
> -
> -static const struct tpm_input_header tpm2_getrandom_header = {
> -	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> -	.length = cpu_to_be32(TPM2_GETRANDOM_IN_SIZE),
> -	.ordinal = cpu_to_be32(TPM2_CC_GET_RANDOM)
> -};
> +struct tpm2_get_random_out {
> +	__be16 size;
> +	u8 buffer[TPM_MAX_RNG_DATA];
> +} __packed;
>  
>  /**
>   * tpm2_get_random() - get random bytes from the TPM RNG
>   *
>   * @chip: TPM chip to use
> - * @out: destination buffer for the random bytes
> + * @dest: destination buffer for the random bytes
>   * @max: the max number of bytes to write to @out
>   *
>   * Return:
> - *    Size of the output buffer, or -EIO on error.
> + * size of the output buffer when the operation is successful.
> + * A negative number for system errors (errno).
>   */
> -int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
> +int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
>  {
> -	struct tpm2_cmd cmd;
> -	u32 recd, rlength;
> -	u32 num_bytes;
> +	struct tpm2_get_random_out *out;
> +	struct tpm_buf buf;
> +	u32 recd;
> +	u32 num_bytes = max;
>  	int err;
>  	int total = 0;
>  	int retries = 5;
> -	u8 *dest = out;
> +	u8 *dest_ptr = dest;
>  
> -	num_bytes = min_t(u32, max, sizeof(cmd.params.getrandom_out.buffer));
> -
> -	if (!out || !num_bytes ||
> -	    max > sizeof(cmd.params.getrandom_out.buffer))
> +	if (!num_bytes || max > TPM_MAX_RNG_DATA)
>  		return -EINVAL;
>  
>  	do {
> -		cmd.header.in = tpm2_getrandom_header;
> -		cmd.params.getrandom_in.size = cpu_to_be16(num_bytes);
> -
> -		err = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd),
> +		err = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS,
> +				   TPM2_CC_GET_RANDOM);
> +		if (err)
> +			return err;
> +		tpm_buf_append_u16(&buf, num_bytes);
> +		err = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE,
>  				       offsetof(struct tpm2_get_random_out,
>  						buffer),
>  				       0, "attempting get random");
>  		if (err)
>  			break;
>  
> -		recd = min_t(u32, be16_to_cpu(cmd.params.getrandom_out.size),
> -			     num_bytes);
> -		rlength = be32_to_cpu(cmd.header.out.length);
> -		if (rlength < offsetof(struct tpm2_get_random_out, buffer) +
> -			      recd)
> +		out = (struct tpm2_get_random_out *)
> +			&buf.data[TPM_HEADER_SIZE];
> +		recd = min_t(u32, be16_to_cpu(out->size), num_bytes);
> +		if (tpm_buf_length(&buf) <
> +		    offsetof(struct tpm2_get_random_out, buffer) + recd)
>  			return -EFAULT;
> -		memcpy(dest, cmd.params.getrandom_out.buffer, recd);
> +		memcpy(dest_ptr, out->buffer, recd);
>  
> -		dest += recd;
> +		dest_ptr += recd;
>  		total += recd;
>  		num_bytes -= recd;
>  	} while (retries-- && total < max);
> @@ -435,7 +412,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
>  {
>  	unsigned int blob_len;
>  	struct tpm_buf buf;
> -	u32 hash, rlength;
> +	u32 hash;
>  	int i;
>  	int rc;
>  
> @@ -510,8 +487,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
>  		rc = -E2BIG;
>  		goto out;
>  	}
> -	rlength = be32_to_cpu(((struct tpm2_cmd *)&buf)->header.out.length);
> -	if (rlength < TPM_HEADER_SIZE + 4 + blob_len) {
> +	if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 4 + blob_len) {
>  		rc = -EFAULT;
>  		goto out;
>  	}
> @@ -621,7 +597,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
>  	u16 data_len;
>  	u8 *data;
>  	int rc;
> -	u32 rlength;
>  
>  	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
>  	if (rc)
> @@ -649,9 +624,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
>  			goto out;
>  		}
>  
> -		rlength = be32_to_cpu(((struct tpm2_cmd *)&buf)
> -					->header.out.length);
> -		if (rlength < TPM_HEADER_SIZE + 6 + data_len) {
> +		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
>  			rc = -EFAULT;
>  			goto out;
>  		}
> -- 
> 2.15.1
> 

tpm_buf_destroy() missing

/Jarkko



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