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Date: Tue, 14 Sep 2021 19:58:12 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: amirmizi6@...il.com, Eyal.Cohen@...oton.com,
oshrialkoby85@...il.com, alexander.steffen@...ineon.com,
robh+dt@...nel.org, mark.rutland@....com, peterhuewe@....de,
jgg@...pe.ca, arnd@...db.de, gregkh@...uxfoundation.org,
benoit.houyere@...com, eajames@...ux.ibm.com, joel@....id.au
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-integrity@...r.kernel.org, oshri.alkoby@...oton.com,
tmaimon77@...il.com, gcwilson@...ibm.com, kgoldman@...ibm.com,
Dan.Morav@...oton.com, oren.tanami@...oton.com,
shmulik.hager@...oton.com, amir.mizinski@...oton.com
Subject: Re: [PATCH v15 1/6] tpm_tis: Fix expected bit handling and send all
bytes in one shot without last byte in exception
On Tue, 2021-09-14 at 18:10 +0300, amirmizi6@...il.com wrote:
> From: Amir Mizinski <amirmizi6@...il.com>
>
> Detected an incorrect implementation of the send command.
> Currently, the driver polls the TPM_STS.stsValid field until TRUE; then it
> reads TPM_STS register again to verify only that TPM_STS.expect field is
> FALSE (i.e., it ignores TPM_STS.stsValid).
> Since TPM_STS.stsValid represents the TPM_STS.expect validity, both fields
> fields should be checked in the same TPM_STS register read value.
This is missing description of what kind of error/consquence this caused.
Perhaps you got something to the klog, or how did you find out about the
issue? Since you have reproduced, please connect it to the reality.
> Modify the signature of 'wait_for_tpm_stat()', add an additional
> "mask_result" parameter to its call and rename it to
> 'tpm_tis_wait_for_stat()' for better alignment with other naming.
> 'tpm_tis_wait_for_stat()' is now polling the TPM_STS with a mask and waits
> for the value in mask_result. Add the ability to check if certain TPM_STS
> bits have been cleared.
The commit description is probably out of sync (not only rename, there is no
parameter called mask_result).
It's also lacking description, how this new parameter is taken advantage of.
E.g.
"Use the new parameter to check that status TPM_STS_VALID is set,
in addition that TPM_STS_EXPECT is zeroed. This prevents a racy
checkk
> In addition, the send command was changed to comply with
> TCG_DesignPrinciples_TPM2p0Driver_vp24_pubrev.pdf as follows:
> - send all command bytes in one loop
> - remove special handling of the last byte
>
> Suggested-by: Benoit Houyere <benoit.houyere@...com>
> Signed-off-by: Amir Mizinski <amirmizi6@...il.com>
> ---
> drivers/char/tpm/tpm_tis_core.c | 68 +++++++++++++++--------------------------
> 1 file changed, 25 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 69579ef..7d5854b 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -44,9 +44,9 @@ static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
> return false;
> }
>
> -static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> - unsigned long timeout, wait_queue_head_t *queue,
> - bool check_cancel)
> +static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, u8 stat,
> + unsigned long timeout,
> + wait_queue_head_t *queue, bool check_cancel)
This naming is not too great, considering that there is already local variable
called status.
> {
> unsigned long stop;
> long rc;
> @@ -55,7 +55,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
>
> /* check current status */
> status = chip->ops->status(chip);
> - if ((status & mask) == mask)
> + if ((status & mask) == stat)
> return 0;
>
> stop = jiffies + timeout;
> @@ -83,7 +83,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
> usleep_range(TPM_TIMEOUT_USECS_MIN,
> TPM_TIMEOUT_USECS_MAX);
> status = chip->ops->status(chip);
> - if ((status & mask) == mask)
> + if ((status & mask) == stat)
> return 0;
> } while (time_before(jiffies, stop));
> }
> @@ -260,9 +260,10 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
>
> while (size < count) {
> rc = wait_for_tpm_stat(chip,
> - TPM_STS_DATA_AVAIL | TPM_STS_VALID,
> - chip->timeout_c,
> - &priv->read_queue, true);
> + TPM_STS_DATA_AVAIL | TPM_STS_VALID,
> + TPM_STS_DATA_AVAIL | TPM_STS_VALID,
> + chip->timeout_c, &priv->read_queue,
> + true);
> if (rc < 0)
> return rc;
> burstcnt = get_burstcount(chip);
> @@ -315,8 +316,9 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> goto out;
> }
>
> - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> - &priv->int_queue, false) < 0) {
> + if (wait_for_tpm_stat(chip, TPM_STS_VALID, TPM_STS_VALID,
> + chip->timeout_c, &priv->int_queue,
> + false) < 0) {
> size = -ETIME;
> goto out;
> }
> @@ -342,61 +344,40 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> int rc, status, burstcnt;
> size_t count = 0;
> - bool itpm = priv->flags & TPM_TIS_ITPM_WORKAROUND;
>
> status = tpm_tis_status(chip);
> if ((status & TPM_STS_COMMAND_READY) == 0) {
> tpm_tis_ready(chip);
> - if (wait_for_tpm_stat
> - (chip, TPM_STS_COMMAND_READY, chip->timeout_b,
> - &priv->int_queue, false) < 0) {
> + if (wait_for_tpm_stat(chip, TPM_STS_COMMAND_READY,
> + TPM_STS_COMMAND_READY,
> + chip->timeout_b, &priv->int_queue,
> + false) < 0) {
> rc = -ETIME;
> goto out_err;
> }
> }
>
> - while (count < len - 1) {
> + while (count < len) {
This.
> burstcnt = get_burstcount(chip);
> if (burstcnt < 0) {
> dev_err(&chip->dev, "Unable to read burstcount\n");
> rc = burstcnt;
> goto out_err;
> }
> - burstcnt = min_t(int, burstcnt, len - count - 1);
> + burstcnt = min_t(int, burstcnt, len - count);
What are these two changes (loop condition and the right above change)?
> rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
> burstcnt, buf + count);
> if (rc < 0)
> goto out_err;
>
> count += burstcnt;
> -
> - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> - &priv->int_queue, false) < 0) {
> - rc = -ETIME;
> - goto out_err;
> - }
> - status = tpm_tis_status(chip);
> - if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) {
> - rc = -EIO;
> - goto out_err;
> - }
> }
> -
> - /* write last byte */
> - rc = tpm_tis_write8(priv, TPM_DATA_FIFO(priv->locality), buf[count]);
> - if (rc < 0)
> - goto out_err;
> -
> - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> - &priv->int_queue, false) < 0) {
> + if (wait_for_tpm_stat(chip, TPM_STS_VALID | TPM_STS_DATA_EXPECT,
> + TPM_STS_VALID, chip->timeout_a,
> + &priv->int_queue, false) < 0) {
> rc = -ETIME;
> goto out_err;
> }
> - status = tpm_tis_status(chip);
> - if (!itpm && (status & TPM_STS_DATA_EXPECT) != 0) {
> - rc = -EIO;
> - goto out_err;
> - }
>
> return 0;
>
> @@ -451,9 +432,10 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
> ordinal = be32_to_cpu(*((__be32 *) (buf + 6)));
>
> dur = tpm_calc_ordinal_duration(chip, ordinal);
> - if (wait_for_tpm_stat
> - (chip, TPM_STS_DATA_AVAIL | TPM_STS_VALID, dur,
> - &priv->read_queue, false) < 0) {
> + if (wait_for_tpm_stat(chip,
> + TPM_STS_DATA_AVAIL | TPM_STS_VALID,
> + TPM_STS_DATA_AVAIL | TPM_STS_VALID,
> + dur, &priv->read_queue, false) < 0) {
> rc = -ETIME;
> goto out_err;
> }
/Jarkko
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