Re: [PATCH v5 14/17] tpm: remove TPM_TRANSMIT_UNLOCKED flag

[Stefan Berger <stefanb@linux.ibm.com>]

On 11/8/18 9:15 AM, Jarkko Sakkinen wrote:
> Added locking as part of tpm_try_get_ops() and tpm_put_ops() as they are
> anyway used in most of the call sites except in tpmrm_release() where we
> take the locks manually.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>   drivers/char/tpm/tpm-chip.c       |  2 ++
>   drivers/char/tpm/tpm-dev-common.c |  4 +---
>   drivers/char/tpm/tpm-interface.c  |  8 --------
>   drivers/char/tpm/tpm.h            |  8 ++------
>   drivers/char/tpm/tpm2-cmd.c       | 13 ++++---------
>   drivers/char/tpm/tpm2-space.c     | 15 ++++++---------
>   6 files changed, 15 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 32db84683c40..157505b0f755 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -58,6 +58,7 @@ int tpm_try_get_ops(struct tpm_chip *chip)
>   	if (!chip->ops)
>   		goto out_lock;
>
> +	mutex_lock(&chip->tpm_mutex);
>   	return 0;
>   out_lock:
>   	up_read(&chip->ops_sem);
> @@ -75,6 +76,7 @@ EXPORT_SYMBOL_GPL(tpm_try_get_ops);
>    */
>   void tpm_put_ops(struct tpm_chip *chip)
>   {
> +	mutex_unlock(&chip->tpm_mutex);
>   	up_read(&chip->ops_sem);
>   	put_device(&chip->dev);
>   }
> diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
> index c7dc54930576..582caefcf19b 100644
> --- a/drivers/char/tpm/tpm-dev-common.c
> +++ b/drivers/char/tpm/tpm-dev-common.c
> @@ -33,7 +33,6 @@ static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   	struct tpm_header *header = (void *)buf;
>   	ssize_t ret, len;
>
> -	mutex_lock(&chip->tpm_mutex);
>   	ret = tpm2_prepare_space(chip, space, buf, bufsiz);
>   	/* If the command is not implemented by the TPM, synthesize a
>   	 * response with a TPM2_RC_COMMAND_CODE return for user-space.
> @@ -48,7 +47,7 @@ static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   	if (ret)
>   		goto out_lock;
>
> -	len = tpm_transmit(chip, buf, bufsiz, TPM_TRANSMIT_UNLOCKED);
> +	len = tpm_transmit(chip, buf, bufsiz, 0);
>   	if (len < 0)
>   		ret = len;
>
> @@ -57,7 +56,6 @@ static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
>   	else
>   		ret = tpm2_commit_space(chip, space, buf, &len);
>   out_lock:
> -	mutex_unlock(&chip->tpm_mutex);
>   	return ret ? ret : len;
>   }
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 8d75c103f280..5865b9671d20 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -227,10 +227,6 @@ ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz,
>   	memcpy(save, buf, save_size);
>
>   	for (;;) {
> -		if (!(flags & TPM_TRANSMIT_UNLOCKED) &&
> -		    !(flags & TPM_TRANSMIT_NESTED))
> -			mutex_lock(&chip->tpm_mutex);
> -
>   		if (chip->ops->clk_enable != NULL)
>   			chip->ops->clk_enable(chip, true);
>
> @@ -257,10 +253,6 @@ ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz,
>   		if (chip->ops->clk_enable != NULL)
>   			chip->ops->clk_enable(chip, false);
>
> -		if (!(flags & TPM_TRANSMIT_UNLOCKED) &&
> -		    !(flags & TPM_TRANSMIT_NESTED))
> -			mutex_unlock(&chip->tpm_mutex);
> -
>   		if (ret < 0)
>   			break;
>   		rc = be32_to_cpu(header->return_code);
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 10a5bcf806aa..c7c06de651a0 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -488,14 +488,10 @@ extern struct idr dev_nums_idr;
>   /**
>    * enum tpm_transmit_flags - flags for tpm_transmit()
>    *
> - * @TPM_TRANSMIT_UNLOCKED:	do not lock the chip
> - * @TPM_TRANSMIT_NESTED:	discard setup steps (power management,
> - *				locality) including locking (i.e. implicit
> - *				UNLOCKED)
> + * %TPM_TRANSMIT_NESTED:	discard setup steps (power management, locality)
>    */
>   enum tpm_transmit_flags {
> -	TPM_TRANSMIT_UNLOCKED	= BIT(0),
> -	TPM_TRANSMIT_NESTED      = BIT(1),
> +	TPM_TRANSMIT_NESTED      = BIT(0),
>   };
>
>   ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz,
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index f2b0e5c52a57..d6abc964ef66 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -652,17 +652,12 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
>   	u32 blob_handle;
>   	int rc;
>
> -	mutex_lock(&chip->tpm_mutex);
> -	rc = tpm2_load_cmd(chip, payload, options, &blob_handle,
> -			   TPM_TRANSMIT_UNLOCKED);
> +	rc = tpm2_load_cmd(chip, payload, options, &blob_handle, 0);
>   	if (rc)
> -		goto out;
> +		return rc;
>
> -	rc = tpm2_unseal_cmd(chip, payload, options, blob_handle,
> -			     TPM_TRANSMIT_UNLOCKED);
> -	tpm2_flush_context_cmd(chip, blob_handle, TPM_TRANSMIT_UNLOCKED);
> -out:
> -	mutex_unlock(&chip->tpm_mutex);
> +	rc = tpm2_unseal_cmd(chip, payload, options, blob_handle, 0);
> +	tpm2_flush_context_cmd(chip, blob_handle, 0);


This lock was covering quite a few commands from being interfered by 
others. Is this still guaranteed to work after or can different 
subsystems like trusted keys and IMA and /dev/tpm0 users interfere with 
this previous atomic sequence ?


>   	return rc;
>   }
>
> diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
> index d1c371db1ab7..341d4b90ba2f 100644
> --- a/drivers/char/tpm/tpm2-space.c
> +++ b/drivers/char/tpm/tpm2-space.c
> @@ -38,8 +38,7 @@ static void tpm2_flush_sessions(struct tpm_chip *chip, struct tpm_space *space)
>
>   	for (i = 0; i < ARRAY_SIZE(space->session_tbl); i++) {
>   		if (space->session_tbl[i])
> -			tpm2_flush_context_cmd(chip, space->session_tbl[i],
> -					       TPM_TRANSMIT_UNLOCKED);
> +			tpm2_flush_context_cmd(chip, space->session_tbl[i], 0);
>   	}
>   }
>
> @@ -83,7 +82,7 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
>   	body_size = sizeof(*ctx) + be16_to_cpu(ctx->blob_size);
>   	tpm_buf_append(&tbuf, &buf[*offset], body_size);
>
> -	rc = tpm_transmit_cmd(chip, &tbuf, 4, TPM_TRANSMIT_UNLOCKED, NULL);
> +	rc = tpm_transmit_cmd(chip, &tbuf, 4, 0, NULL);
>   	if (rc < 0) {
>   		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
>   			 __func__, rc);
> @@ -131,7 +130,7 @@ static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
>
>   	tpm_buf_append_u32(&tbuf, handle);
>
> -	rc = tpm_transmit_cmd(chip, &tbuf, 0, TPM_TRANSMIT_UNLOCKED, NULL);
> +	rc = tpm_transmit_cmd(chip, &tbuf, 0, 0, NULL);
>   	if (rc < 0) {
>   		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
>   			 __func__, rc);
> @@ -167,8 +166,7 @@ void tpm2_flush_space(struct tpm_chip *chip)
>
>   	for (i = 0; i < ARRAY_SIZE(space->context_tbl); i++)
>   		if (space->context_tbl[i] && ~space->context_tbl[i])
> -			tpm2_flush_context_cmd(chip, space->context_tbl[i],
> -					       TPM_TRANSMIT_UNLOCKED);
> +			tpm2_flush_context_cmd(chip, space->context_tbl[i], 0);
>
>   	tpm2_flush_sessions(chip, space);
>   }
> @@ -417,7 +415,7 @@ static int tpm2_map_response_header(struct tpm_chip *chip, u32 cc, u8 *rsp,
>
>   	return 0;
>   out_no_slots:
> -	tpm2_flush_context_cmd(chip, phandle, TPM_TRANSMIT_UNLOCKED);
> +	tpm2_flush_context_cmd(chip, phandle, 0);
>   	dev_warn(&chip->dev, "%s: out of slots for 0x%08X\n", __func__,
>   		 phandle);
>   	return -ENOMEM;
> @@ -504,8 +502,7 @@ static int tpm2_save_space(struct tpm_chip *chip)
>   		} else if (rc)
>   			return rc;
>
> -		tpm2_flush_context_cmd(chip, space->context_tbl[i],
> -				       TPM_TRANSMIT_UNLOCKED);
> +		tpm2_flush_context_cmd(chip, space->context_tbl[i], 0);
>   		space->context_tbl[i] = ~0;
>   	}
>