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

[Roberto Sassu]

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.sa...@huawei.com>
Tested-by: Jarkko Sakkinen <jarkko.sakki...@linux.intel.com>
---
  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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