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From: Roberto Sassu <roberto.sassu@huawei.com>
To: <jarkko.sakkinen@linux.intel.com>, <zohar@linux.ibm.com>,
	<david.safford@ge.com>, <monty.wiseman@ge.com>
Cc: <linux-integrity@vger.kernel.org>,
	<linux-security-module@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <silviu.vlasceanu@huawei.com>,
	Roberto Sassu <roberto.sassu@huawei.com>,
	<stable@vger.kernel.org>
Subject: [PATCH v5 6/7] tpm: ensure that the output of PCR read contains the correct digest size
Date: Wed, 14 Nov 2018 16:31:07 +0100	[thread overview]
Message-ID: <20181114153108.12907-7-roberto.sassu@huawei.com> (raw)
In-Reply-To: <20181114153108.12907-1-roberto.sassu@huawei.com>

This patch protects against data corruption that could happen in the bus,
by checking that that the digest size returned by the TPM during a PCR read
matches the size of the algorithm passed to tpm2_pcr_read().

This check is performed after information about the PCR banks has been
retrieved.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: stable@vger.kernel.org
---
 drivers/char/tpm/tpm2-cmd.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index acaaab72ef2e..974465f04b78 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -179,15 +179,29 @@ struct tpm2_pcr_read_out {
 int tpm2_pcr_read(struct tpm_chip *chip, u32 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 < chip->nr_allocated_banks &&
+		     chip->allocated_banks[i].alg_id != digest_struct->alg_id;
+		     i++)
+			;
+
+		if (i == chip->nr_allocated_banks)
+			return -EINVAL;
+
+		expected_digest_size = chip->allocated_banks[i].digest_size;
+	}
+
 	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 	if (rc)
 		return rc;
@@ -207,7 +221,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 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 > sizeof(digest_struct->digest) ||
+	    (!digest_size_ptr && digest_size != expected_digest_size)) {
 		rc = -EINVAL;
 		goto out;
 	}
-- 
2.17.1


  parent reply	other threads:[~2018-11-14 15:36 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-14 15:31 [PATCH v5 0/7] tpm: retrieve digest size of unknown algorithms from TPM Roberto Sassu
2018-11-14 15:31 ` [PATCH v5 1/7] tpm: dynamically allocate the allocated_banks array Roberto Sassu
2018-11-16 13:36   ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 2/7] tpm: remove definition of TPM2_ACTIVE_PCR_BANKS Roberto Sassu
2018-11-16 13:38   ` Jarkko Sakkinen
2018-11-28  7:50     ` Roberto Sassu
2018-11-28 12:17     ` Roberto Sassu
2018-11-29 12:04       ` Roberto Sassu
2018-11-30 19:41         ` Jarkko Sakkinen
2018-11-30 19:45           ` Jarkko Sakkinen
2018-11-30 22:18             ` Jarkko Sakkinen
2018-12-03  9:59             ` Roberto Sassu
2018-12-03 17:31               ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 3/7] tpm: rename and export tpm2_digest and tpm2_algorithms Roberto Sassu
2018-11-14 15:31 ` [PATCH v5 4/7] tpm: modify tpm_pcr_read() definition to pass a TPM hash algorithm Roberto Sassu
2018-11-16 13:41   ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 5/7] tpm: retrieve digest size of unknown algorithms with PCR read Roberto Sassu
2018-11-14 15:31 ` Roberto Sassu [this message]
2018-11-16 13:41   ` [PATCH v5 6/7] tpm: ensure that the output of PCR read contains the correct digest size Jarkko Sakkinen
2018-11-16 16:06     ` Roberto Sassu
2018-11-18  7:32       ` Jarkko Sakkinen
2018-11-19  8:14         ` Roberto Sassu
2018-11-19 14:33           ` Jarkko Sakkinen
2018-11-19 15:09             ` Roberto Sassu
2018-11-19 16:07               ` Jarkko Sakkinen
2018-11-28  8:40                 ` Roberto Sassu
2018-11-28 19:19                   ` Jarkko Sakkinen
2018-11-14 15:31 ` [PATCH v5 7/7] tpm: pass an array of tpm_bank_list structures to tpm_pcr_extend() Roberto Sassu
2018-11-16 15:03   ` Jarkko Sakkinen
2018-11-16 15:55     ` Roberto Sassu
2018-11-18  7:27       ` Jarkko Sakkinen
2018-11-19  4:57         ` Mimi Zohar
2018-11-19  8:16           ` Roberto Sassu
2018-11-19 14:33             ` Mimi Zohar
2018-11-19 14:39             ` Jarkko Sakkinen
2018-11-18  7:29       ` Jarkko Sakkinen
2018-11-19  8:22         ` Roberto Sassu
2018-11-19 14:42           ` Jarkko Sakkinen

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