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

[Roberto Sassu <roberto.sassu@huawei.com>]

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.sassu@huawei.com>
>> Tested-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      | 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
> 

-- 
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Bo PENG, Jian LI, Yanli SHI