Re: [PATCH v7 1/5] tpm: dynamically allocate the allocated_banks array

Roberto Sassu <roberto.sassu@xxxxxxxxxx> · Fri, 21 Dec 2018 10:40:09 +0100

On 12/20/2018 3:55 PM, Jarkko Sakkinen wrote:
On Thu, Dec 13, 2018 at 11:29:41AM +0100, Roberto Sassu wrote:
This patch renames active_banks (member of tpm_chip) to allocated_banks,
stores the number of allocated PCR banks in nr_allocated_banks (new member
of tpm_chip), and replaces the static array with a pointer to a dynamically
allocated array.

tpm2_get_pcr_allocation() determines if a PCR bank is allocated by checking
the mask in the TPML_PCR_SELECTION structure returned by the TPM for
TPM2_Get_Capability(). If a bank is not allocated, the TPM returns that
bank in TPML_PCR_SELECTION, with all bits in the mask set to zero. In this
case, the bank is not included in chip->allocated_banks, to avoid that TPM
driver users unnecessarily calculate a digest for that bank.

One PCR bank with algorithm set to SHA1 is always allocated for TPM 1.x.

As a consequence of the introduction of nr_allocated_banks,
tpm_pcr_extend() does not check anymore if the algorithm stored in tpm_chip
is equal to zero.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
  drivers/char/tpm/tpm-chip.c      |  1 +
  drivers/char/tpm/tpm-interface.c | 18 +++++++++--------
  drivers/char/tpm/tpm.h           |  3 ++-
  drivers/char/tpm/tpm1-cmd.c      | 10 ++++++++++
  drivers/char/tpm/tpm2-cmd.c      | 34 ++++++++++++++++++++++----------
  5 files changed, 47 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 32db84683c40..ce851c62bb68 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -160,6 +160,7 @@ static void tpm_dev_release(struct device *dev)
  	kfree(chip->log.bios_event_log);
  	kfree(chip->work_space.context_buf);
  	kfree(chip->work_space.session_buf);
+	kfree(chip->allocated_banks);
  	kfree(chip);
  }
  
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index d9439f9abe78..7b80919228be 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -488,8 +488,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
  int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
  {
  	int rc;
-	struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)];
-	u32 count = 0;
+	struct tpm2_digest *digest_list;
  	int i;
  
  	chip = tpm_find_get_ops(chip);
@@ -497,16 +496,19 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
  		return -ENODEV;
  
  	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-		memset(digest_list, 0, sizeof(digest_list));
+		digest_list = kcalloc(chip->nr_allocated_banks,
+				      sizeof(*digest_list), GFP_KERNEL);
+		if (!digest_list)
+			return -ENOMEM;

You could preallocate digest list and place it to struct tpm_chip
instead of doing it everytime tpm_pcr_extend() called.

This part will be removed with patch 5/5.


-		for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
-			    chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
-			digest_list[i].alg_id = chip->active_banks[i];
+		for (i = 0; i < chip->nr_allocated_banks; i++) {
+			digest_list[i].alg_id = chip->allocated_banks[i];
  			memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
-			count++;
  		}
  
-		rc = tpm2_pcr_extend(chip, pcr_idx, count, digest_list);
+		rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_allocated_banks,
+				     digest_list);
+		kfree(digest_list);
  		tpm_put_ops(chip);
  		return rc;
  	}
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f27d1f38a93d..6b94306ab7c5 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -257,7 +257,8 @@ struct tpm_chip {
  	const struct attribute_group *groups[3];
  	unsigned int groups_cnt;
  
-	u16 active_banks[7];
+	u32 nr_allocated_banks;
+	u16 *allocated_banks;
  #ifdef CONFIG_ACPI
  	acpi_handle acpi_dev_handle;
  	char ppi_version[TPM_PPI_VERSION_LEN + 1];
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 6f306338953b..0874743ca96d 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -709,6 +709,16 @@ int tpm1_auto_startup(struct tpm_chip *chip)
  		goto out;
  	}
  
+	chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
+					GFP_KERNEL);
+	if (!chip->allocated_banks) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	chip->allocated_banks[0] = TPM2_ALG_SHA1;
+	chip->nr_allocated_banks = 1;
+
  	return rc;
  out:
  	if (rc > 0)
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index a6bec13afa69..245669a7aba5 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -234,7 +234,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
  	int i;
  	int j;
  
-	if (count > ARRAY_SIZE(chip->active_banks))
+	if (count > chip->nr_allocated_banks)
  		return -EINVAL;
  
  	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
@@ -825,11 +825,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
  	void *marker;
  	void *end;
  	void *pcr_select_offset;
-	unsigned int count;
  	u32 sizeof_pcr_selection;
+	u32 nr_possible_banks;
+	u32 nr_alloc_banks = 0;
+	u16 hash_alg;
  	u32 rsp_len;
  	int rc;
  	int i = 0;
+	int j;
  
  	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
  	if (rc)
@@ -844,11 +847,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
  	if (rc)
  		goto out;
  
-	count = be32_to_cpup(
+	nr_possible_banks = be32_to_cpup(
  		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
  
-	if (count > ARRAY_SIZE(chip->active_banks)) {
-		rc = -ENODEV;
+	chip->allocated_banks = kcalloc(nr_possible_banks,
+					sizeof(*chip->allocated_banks),
+					GFP_KERNEL);
+	if (!chip->allocated_banks) {
+		rc = -ENOMEM;
  		goto out;
  	}
  
@@ -857,7 +863,7 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
  	rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
  	end = &buf.data[rsp_len];
  
-	for (i = 0; i < count; i++) {
+	for (i = 0; i < nr_possible_banks; i++) {
  		pcr_select_offset = marker +
  			offsetof(struct tpm2_pcr_selection, size_of_select);
  		if (pcr_select_offset >= end) {
@@ -866,17 +872,25 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
  		}
  
  		memcpy(&pcr_selection, marker, sizeof(pcr_selection));
-		chip->active_banks[i] = be16_to_cpu(pcr_selection.hash_alg);
+		hash_alg = be16_to_cpu(pcr_selection.hash_alg);
+
+		for (j = 0; j < pcr_selection.size_of_select; j++)
+			if (pcr_selection.pcr_select[j])
+				break;
+
+		if (j < pcr_selection.size_of_select) {
+			chip->allocated_banks[nr_alloc_banks] = hash_alg;
+			nr_alloc_banks++;
+		}

The same comment as before: you should use memchr_inv() here.

Ok.

Roberto


+
  		sizeof_pcr_selection = sizeof(pcr_selection.hash_alg) +
  			sizeof(pcr_selection.size_of_select) +
  			pcr_selection.size_of_select;
  		marker = marker + sizeof_pcr_selection;
  	}
  
+	chip->nr_allocated_banks = nr_alloc_banks;
  out:
-	if (i < ARRAY_SIZE(chip->active_banks))
-		chip->active_banks[i] = TPM2_ALG_ERROR;
-
  	tpm_buf_destroy(&buf);
  
  	return rc;
--
2.17.1


/Jarkko


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