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

[Roberto Sassu]

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.sa...@huawei.com>
---
  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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