From: Mimi Zohar <zohar@linux.ibm.com>
To: Roberto Sassu <roberto.sassu@huawei.com>,
jarkko.sakkinen@linux.intel.com
Cc: linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, silviu.vlasceanu@huawei.com
Subject: Re: [PATCH v3 5/5] tpm: ensure that output of PCR read contains the correct digest size
Date: Thu, 01 Nov 2018 12:52:10 -0400 [thread overview]
Message-ID: <1541091130.4035.41.camel@linux.ibm.com> (raw)
In-Reply-To: <20181030154711.2782-6-roberto.sassu@huawei.com>
On Tue, 2018-10-30 at 16:47 +0100, Roberto Sassu wrote:
> This patch ensures that the digest size returned by the TPM during a PCR
> read matches the size of the algorithm passed as argument to
> tpm2_pcr_read(). The check is performed after information about the PCR
> banks has been retrieved.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
> drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 8e821e7b4674..477dcc30fc53 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out {
> int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
> struct tpm_digest *digest_struct, u16 *digest_size_ptr)
> {
> + int i;
> int rc;
> struct tpm_buf buf;
> struct tpm2_pcr_read_out *out;
> u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
> u16 digest_size;
> + u16 expected_digest_size = 0;
>
> if (pcr_idx >= TPM2_PLATFORM_PCR)
> return -EINVAL;
>
> + if (!digest_size_ptr) {
> + for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
> + chip->active_banks[i].alg_id != digest_struct->alg_id; i++)
> + ;
> +
> + if (i == ARRAY_SIZE(chip->active_banks))
> + return -EINVAL;
> +
> + expected_digest_size = chip->active_banks[i].digest_size;
> + }
> +
> rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
> if (rc)
> return rc;
> @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx,
>
> out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
> digest_size = be16_to_cpu(out->digest_size);
> - if (digest_size > sizeof(digest_struct->digest)) {
> + if ((digest_size_ptr && digest_size > sizeof(digest_struct->digest)) ||
The returned digest size should never be larger than the structure
field. The digest_size_ptr test is unnecessary.
Mimi
> + (!digest_size_ptr && digest_size != expected_digest_size)) {
> rc = -EINVAL;
> goto out;
> }
prev parent reply other threads:[~2018-11-01 16:52 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-30 15:47 [PATCH v3 0/5] tpm: retrieve digest size of unknown algorithms from TPM Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 1/5] tpm: change the end marker of the active_banks array to zero Roberto Sassu
2018-10-30 19:45 ` Jarkko Sakkinen
2018-10-31 14:43 ` Mimi Zohar
2018-11-01 14:42 ` Mimi Zohar
2018-11-05 8:10 ` Roberto Sassu
2018-11-05 13:02 ` Mimi Zohar
2018-11-05 8:07 ` Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 2/5] tpm: rename and export tpm2_digest and tpm2_algorithms Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 3/5] tpm: modify tpm_pcr_read() definition to pass a TPM hash algorithm Roberto Sassu
2018-10-30 15:47 ` [PATCH v3 4/5] tpm: retrieve digest size of unknown algorithms with PCR read Roberto Sassu
2018-11-01 16:02 ` Mimi Zohar
2018-11-01 16:23 ` Mimi Zohar
2018-11-05 9:47 ` Roberto Sassu
2018-11-05 12:01 ` Jarkko Sakkinen
2018-11-05 13:09 ` Roberto Sassu
2018-11-05 14:48 ` Mimi Zohar
2018-11-05 17:13 ` Jarkko Sakkinen
2018-11-05 17:10 ` Jarkko Sakkinen
2018-10-30 15:47 ` [PATCH v3 5/5] tpm: ensure that output of PCR read contains the correct digest size Roberto Sassu
2018-10-30 19:52 ` Jarkko Sakkinen
2018-10-31 8:16 ` Roberto Sassu
2018-11-01 14:32 ` Jarkko Sakkinen
2018-11-01 16:52 ` Mimi Zohar [this message]
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