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Message-ID: <20200408183324.GB33486@linux.intel.com>
Date: Wed, 8 Apr 2020 21:33:24 +0300
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: amirmizi6@...il.com
Cc: 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,
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,
Christophe Ricard <christophe-h.ricard@...com>
Subject: Re: [PATCH v6 2/7] tpm: tpm_tis: Add check_data handle to
tpm_tis_phy_ops
On Tue, Apr 07, 2020 at 07:20:39PM +0300, amirmizi6@...il.com wrote:
> From: Amir Mizinski <amirmizi6@...il.com>
>
> In order to validate data integrity we need to compute the crc over the data
> sent in lower layer (I2C for instance).
s/crc/CRC/
> To do that tpm_tis_check_data() calls a "check_data" operation (if available).
"check_data" does not exist.
> If data integrity check fails, a retry to save the sent/received
> data is implemented in tpm_tis_send_main()/tpm_tis_recv() functions.
>
> Considering this commit, the following steps are done when sending a command:
> 1. Host writes to TPM_STS.commandReady.
> 2. Host writes command.
> 3. Host checks that TPM received data is valid.
> 4. If data is currupted go to step 1.
>
> When receiving data:
> 1. Host checks that TPM_STS.dataAvail is set.
> 2. Host saves received data.
> 3. Host checks that received data is correct.
> 4. If data is currupted Host writes to TPM_STS.responseRetry and go to
> step 1.
These sequences in the commit message look somewhat uselss. Maybe
just remove them.
>
> Co-developed-by: Christophe Ricard <christophe-h.ricard@...com>
> Signed-off-by: Christophe Ricard <christophe-h.ricard@...com>
> Signed-off-by: Amir Mizinski <amirmizi6@...il.com>
> ---
> drivers/char/tpm/tpm_tis_core.c | 102 +++++++++++++++++++++++++---------------
> drivers/char/tpm/tpm_tis_core.h | 3 ++
> 2 files changed, 67 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 27c6ca0..6c4f232 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -242,6 +242,15 @@ static u8 tpm_tis_status(struct tpm_chip *chip)
> return status;
> }
>
> +static bool tpm_tis_check_data(struct tpm_chip *chip, const u8 *buf, size_t len)
Not sure if this is the best possible function name, "check" can
mean almost anything.
> +{
> + struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> +
> + if (priv->phy_ops->check_data)
> + return priv->phy_ops->check_data(priv, buf, len);
New line here before the return statement.
> + return true;
> +}
> +
> static void tpm_tis_ready(struct tpm_chip *chip)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> @@ -308,47 +317,59 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> int size = 0;
> - int status;
> + int status, i;
> u32 expected;
> + bool check_data = false;
>
> - if (count < TPM_HEADER_SIZE) {
> - size = -EIO;
> - goto out;
> - }
> + for (i = 0; i < TPM_RETRY; i++) {
> + if (count < TPM_HEADER_SIZE) {
> + size = -EIO;
> + goto out;
> + }
>
> - size = recv_data(chip, buf, TPM_HEADER_SIZE);
> - /* read first 10 bytes, including tag, paramsize, and result */
> - if (size < TPM_HEADER_SIZE) {
> - dev_err(&chip->dev, "Unable to read header\n");
> - goto out;
> - }
> + size = recv_data(chip, buf, TPM_HEADER_SIZE);
> + /* read first 10 bytes, including tag, paramsize, and result */
> + if (size < TPM_HEADER_SIZE) {
> + dev_err(&chip->dev, "Unable to read header\n");
> + goto out;
> + }
>
> - expected = be32_to_cpu(*(__be32 *) (buf + 2));
> - if (expected > count || expected < TPM_HEADER_SIZE) {
> - size = -EIO;
> - goto out;
> - }
> + expected = be32_to_cpu(*(__be32 *) (buf + 2));
> + if (expected > count || expected < TPM_HEADER_SIZE) {
> + size = -EIO;
> + goto out;
> + }
>
> - size += recv_data(chip, &buf[TPM_HEADER_SIZE],
> - expected - TPM_HEADER_SIZE);
> - if (size < expected) {
> - dev_err(&chip->dev, "Unable to read remainder of result\n");
> - size = -ETIME;
> - goto out;
> - }
> + size += recv_data(chip, &buf[TPM_HEADER_SIZE],
> + expected - TPM_HEADER_SIZE);
> + if (size < expected) {
> + dev_err(&chip->dev, "Unable to read remainder of result\n");
> + size = -ETIME;
> + goto out;
> + }
>
> - if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> - &priv->int_queue, false) < 0) {
> - size = -ETIME;
> - goto out;
> + if (wait_for_tpm_stat(chip, TPM_STS_VALID, chip->timeout_c,
> + &priv->int_queue, false) < 0) {
> + size = -ETIME;
> + goto out;
> + }
> +
> + status = tpm_tis_status(chip);
> + if (status & TPM_STS_DATA_AVAIL) { /* retry? */
> + dev_err(&chip->dev, "Error left over data\n");
> + size = -EIO;
> + goto out;
> + }
> +
> + check_data = tpm_tis_check_data(chip, buf, size);
> + if (!check_data)
> + tpm_tis_write8(priv, TPM_STS(priv->locality),
> + TPM_STS_RESPONSE_RETRY);
> + else
> + break;
> }
> - status = tpm_tis_status(chip);
> - if (status & TPM_STS_DATA_AVAIL) { /* retry? */
> - dev_err(&chip->dev, "Error left over data\n");
> + if (!check_data)
> size = -EIO;
> - goto out;
> - }
> -
> out:
> tpm_tis_ready(chip);
> return size;
> @@ -453,14 +474,19 @@ static void disable_interrupts(struct tpm_chip *chip)
> static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> - int rc;
> + int rc, i;
> u32 ordinal;
> unsigned long dur;
> + bool data_valid = false;
>
> - rc = tpm_tis_send_data(chip, buf, len);
> - if (rc < 0)
> - return rc;
> -
> + for (i = 0; i < TPM_RETRY && !data_valid; i++) {
> + rc = tpm_tis_send_data(chip, buf, len);
> + if (rc < 0)
> + return rc;
> + data_valid = tpm_tis_check_data(chip, buf, len);
> + }
> + if (!data_valid)
> + return -EIO;
> /* go and do it */
> rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
> if (rc < 0)
> diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> index d06c65b..486c2e9 100644
> --- a/drivers/char/tpm/tpm_tis_core.h
> +++ b/drivers/char/tpm/tpm_tis_core.h
> @@ -34,6 +34,7 @@ enum tis_status {
> TPM_STS_GO = 0x20,
> TPM_STS_DATA_AVAIL = 0x10,
> TPM_STS_DATA_EXPECT = 0x08,
> + TPM_STS_RESPONSE_RETRY = 0x02,
> };
>
> enum tis_int_flags {
> @@ -106,6 +107,8 @@ struct tpm_tis_phy_ops {
> int (*read16)(struct tpm_tis_data *data, u32 addr, u16 *result);
> int (*read32)(struct tpm_tis_data *data, u32 addr, u32 *result);
> int (*write32)(struct tpm_tis_data *data, u32 addr, u32 src);
> + bool (*check_data)(struct tpm_tis_data *data, const u8 *buf,
> + size_t len);
Aren't you validating the contents of the buf?
/Jarkko
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