Re: [PATCH v4 1/6] tpm: dynamically allocate active_banks array

Roberto Sassu <roberto.sassu@xxxxxxxxxx> · Tue, 13 Nov 2018 14:34:39 +0100

On 11/8/2018 2:46 PM, Jarkko Sakkinen wrote:
Orrayn Tue, Nov 06, 2018 at 04:01:54PM +0100, Roberto Sassu wrote:
This patch removes the hard-coded limit of the active_banks array size.
It stores in the tpm_chip structure the number of active PCR banks,
determined in tpm2_get_pcr_allocation(), and replaces the static array
with a pointer to a dynamically allocated array.

As a consequence of the introduction of nr_active_banks, tpm_pcr_extend()
does not check anymore if the algorithm stored in tpm_chip is equal to
zero. The active_banks array always contains valid algorithms.

Fixes: 1db15344f874 ("tpm: implement TPM 2.0 capability to get active
PCR banks")

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
  drivers/char/tpm/tpm-chip.c      |  1 +
  drivers/char/tpm/tpm-interface.c | 19 ++++++++++++-------
  drivers/char/tpm/tpm.h           |  3 ++-
  drivers/char/tpm/tpm2-cmd.c      | 17 ++++++++---------
  4 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 46caadca916a..2a9e8b744436 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->active_banks);
  	kfree(chip);
  }
  
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1a803b0cf980..ba7ca6b3e664 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1039,8 +1039,7 @@ static int tpm1_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash,
  int tpm_pcr_extend(struct tpm_chip *chip, int 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);
@@ -1048,16 +1047,22 @@ int tpm_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
  		return -ENODEV;

Should take digest_list as input. Probably callers could re-use the
same digest_list array multiple times?

Move struct tpm_chip to include/linux/tpm.h so that the caller can query
nr_active_banks and active_banks and can create the digest array by
itself. Lets do this right at once now that this is being restructured.

I have to move also other structures and #define. Wouldn't be better to
introduce a new function to pass to the caller active_banks and
nr_active_banks?

Roberto


  
  	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-		memset(digest_list, 0, sizeof(digest_list));
+		digest_list = kmalloc_array(chip->nr_active_banks,
+					    sizeof(*digest_list), GFP_KERNEL);
+		if (!digest_list)
+			return -ENOMEM;
  
-		for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
-			    chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
+		memset(digest_list, 0,
+		       chip->nr_active_banks * sizeof(*digest_list));

You should use kcalloc() to allocate digest_list.

+
+		for (i = 0; i < chip->nr_active_banks; i++) {
  			digest_list[i].alg_id = chip->active_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_active_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 f3501d05264f..98368c3a6ff7 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -248,7 +248,8 @@ struct tpm_chip {
  	const struct attribute_group *groups[3];
  	unsigned int groups_cnt;
  
-	u16 active_banks[7];
+	u32 nr_active_banks;
+	u16 *active_banks;
  #ifdef CONFIG_ACPI
  	acpi_handle acpi_dev_handle;
  	char ppi_version[TPM_PPI_VERSION_LEN + 1];
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index c31b490bd41d..533089cede07 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -242,7 +242,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
  	int i;
  	int j;
  
-	if (count > ARRAY_SIZE(chip->active_banks))
+	if (count > chip->nr_active_banks)
  		return -EINVAL;
  
  	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
@@ -859,7 +859,6 @@ 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 rsp_len;
  	int rc;
@@ -878,11 +877,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
  	if (rc)
  		goto out;
  
-	count = be32_to_cpup(
+	chip->nr_active_banks = be32_to_cpup(
  		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
  
-	if (count > ARRAY_SIZE(chip->active_banks)) {
-		rc = -ENODEV;
+	chip->active_banks = kmalloc_array(chip->nr_active_banks,
+					   sizeof(*chip->active_banks),
+					   GFP_KERNEL);
+	if (!chip->active_banks) {
+		rc = -ENOMEM;
  		goto out;
  	}
  
@@ -891,7 +893,7 @@ 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 < chip->nr_active_banks; i++) {
  		pcr_select_offset = marker +
  			offsetof(struct tpm2_pcr_selection, size_of_select);
  		if (pcr_select_offset >= end) {
@@ -908,9 +910,6 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
  	}
  
  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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