[PATCH v10, RESEND 1/6] tpm: dynamically allocate the allocated_banks array

Roberto Sassu
2019-02-06T16:28:04Z

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>
---
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 | 31 +++++++++++++++++++++----------
5 files changed, 44 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 2019635d0f70..9865776ee2cd 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -265,6 +265,7 @@ 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 ce39fe043bcb..24f0eed531a0 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -309,8 +309,7 @@ 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);
@@ -318,16 +317,19 @@ 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;

- 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 183e2b93e0fe..cd330ace6248 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 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)
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 971d46efaca5..bd20b9a61fc0 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);
@@ -808,8 +808,10 @@ 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;
@@ -826,11 +828,14 @@ 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;
}

@@ -839,7 +844,7 @@ 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) {
@@ -848,17 +853,23 @@ 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);
+
+ pcr_select_offset = memchr_inv(pcr_selection.pcr_select, 0,
+ pcr_selection.size_of_select);
+ if (pcr_select_offset) {
+ chip->allocated_banks[nr_alloc_banks] = hash_alg;
+ nr_alloc_banks++;
+ }
+
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