Re: [PATCH v5 04/17] tpm: call tpm2_flush_space() on error in tpm_try_transmit()

On 11/8/18 9:15 AM, Jarkko Sakkinen wrote:

Always call tpm2_flush_space() on failure in tpm_try_transmit() so that the volatile memory of the TPM gets cleared. If /dev/tpm0 does not have sufficient permissions (usually it has), this could lead to the leakage of TPM objects. Through /dev/tpmrm0 this issue does not raise any new security concerns.

Cc: stable@vger.kernel.org Fixes: 745b361e989a ("tpm:tpm: infrastructure for TPM spaces") Signed-off-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com

Reviewed-by: Stefan Berger stefanb@linux.ibm.com

---

drivers/char/tpm/tpm-interface.c | 33 +++++++++++++++----------------- drivers/char/tpm/tpm.h | 1 + drivers/char/tpm/tpm2-space.c | 2 +- 3 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 64510ed81b46..c9efd1b9fd2c 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -224,14 +224,14 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,

rc = tpm2_prepare_space(chip, space, ordinal, buf); if (rc)

• goto out;
  

• goto out_idle;
  
  

  rc = chip->ops->send(chip, buf, count); if (rc < 0) { if (rc != -EPIPE) dev_err(&chip->dev, "%s: tpm_send: error %d\n", __func__, rc);

• goto out;
  

• goto out_space;
  

  }

  if (chip->flags & TPM_CHIP_FLAG_IRQ)

@@ -247,7 +247,7 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, if (chip->ops->req_canceled(chip, status)) { dev_err(&chip->dev, "Operation Canceled\n"); rc = -ECANCELED;

• 	goto out;
  

• 	goto out_space;
  

  }

  tpm_msleep(TPM_TIMEOUT_POLL);

@@ -257,30 +257,27 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, chip->ops->cancel(chip); dev_err(&chip->dev, "Operation Timed out\n"); rc = -ETIME;

• goto out;

• goto out_space;

  out_recv: len = chip->ops->recv(chip, buf, bufsiz); if (len < 0) { rc = len;

• dev_err(&chip->dev,
  

• 	"tpm_transmit: tpm_recv: error %d\n", rc);
  

• goto out;
  

• } else if (len < TPM_HEADER_SIZE) {

• dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
  

• } else if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length)) rc = -EFAULT;

• goto out;
  

• }

• if (len != be32_to_cpu(header->length)) {

• rc = -EFAULT;
  

• goto out;
  

+out_space:

• if (rc) {

• tpm2_flush_space(chip);
  

• } else {

• rc = tpm2_commit_space(chip, space, ordinal, buf, &len);
  

• if (rc)
  

• 	dev_err(&chip->dev, "tpm2_commit_space: error %d\n",
  

• 		rc);
  

  }

• rc = tpm2_commit_space(chip, space, ordinal, buf, &len);
• if (rc)

• dev_err(&chip->dev, "tpm2_commit_space: error %d\n", rc);
  

-out: +out_idle: /* may fail but do not override previous error value in rc */ tpm_go_idle(chip, flags);

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 49bca4d1e786..229ac42b644e 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -579,6 +579,7 @@ int tpm2_probe(struct tpm_chip *chip); int tpm2_find_cc(struct tpm_chip *chip, u32 cc); int tpm2_init_space(struct tpm_space *space); void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space); +void tpm2_flush_space(struct tpm_chip *chip); int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u32 cc, u8 *cmd); int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index 1131a8e7b79b..d53c882268ff 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -162,7 +162,7 @@ static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf, return 0; }

-static void tpm2_flush_space(struct tpm_chip *chip) +void tpm2_flush_space(struct tpm_chip *chip) { struct tpm_space *space = &chip->work_space; int i;