tpm: dynamically allocate the allocated_banks array

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@huawei.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index ec5f3693c096..e7d3228a0f37 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -696,6 +696,16 @@ 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)