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SubjectRe: [PATCH v9 6/6] tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()
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On 2/1/2019 8:15 PM, Mimi Zohar wrote:
> Hi Roberto,
>
> Sorry for the delayed review.  A few comments inline below, minor
> suggestions.
>
>> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
>> index cc12f3449a72..e6b2dcb0846a 100644
>> --- a/security/integrity/ima/ima.h
>> +++ b/security/integrity/ima/ima.h
>> @@ -56,6 +56,7 @@ extern int ima_policy_flag;
>> extern int ima_hash_algo;
>> extern int ima_appraise;
>> extern struct tpm_chip *ima_tpm_chip;
>> +extern struct tpm_digest *digests;
>>
>> /* IMA event related data */
>> struct ima_event_data {
>> diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
>> index 6bb42a9c5e47..296a965b11ef 100644
>> --- a/security/integrity/ima/ima_init.c
>> +++ b/security/integrity/ima/ima_init.c
>> @@ -27,6 +27,7 @@
>> /* name for boot aggregate entry */
>> static const char boot_aggregate_name[] = "boot_aggregate";
>> struct tpm_chip *ima_tpm_chip;
>> +struct tpm_digest *digests;
>
> "digests" is used in the new ima_init_digests() and in
> ima_pcr_extend().  It's nice that the initialization routines are
> grouped together here in ima_init.c, but wouldn't it better to define
> "digests" in ima_queued.c, where it is currently being used?
>  "digests" could then be defined as static.
>
>>
>> /* Add the boot aggregate to the IMA measurement list and extend
>> * the PCR register.
>> @@ -104,6 +105,24 @@ void __init ima_load_x509(void)
>> }
>> #endif
>>
>> +int __init ima_init_digests(void)
>> +{
>> + int i;
>> +
>> + if (!ima_tpm_chip)
>> + return 0;
>> +
>> + digests = kcalloc(ima_tpm_chip->nr_allocated_banks, sizeof(*digests),
>> + GFP_NOFS);
>> + if (!digests)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++)
>> + digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
>> +
>> + return 0;
>> +}
>> +
>> int __init ima_init(void)
>> {
>> int rc;
>> @@ -125,6 +144,9 @@ int __init ima_init(void)
>>
>> ima_load_kexec_buffer();
>>
>> + rc = ima_init_digests();
>
> Ok. Getting the tpm chip is at the beginning of this function.
>  Deferring allocating "digests" to here, avoids having to free memory
> on failure.

If I understood the code correctly, ima_init() does not undo the actions
of previous functions. For example, if ima_init_template() fails,
ima_shash_tfm is not freed.

Probably, this can be improved later.

Roberto


> ima_load_kexec_buffer() restores prior measurements, but doesn't
> extend the TPM.  For anyone reading the code, a short comment above
> ima_load_kexec_buffer() would make sense.
>
> Mimi
>
>> + if (rc != 0)
>> + return rc;
>> rc = ima_add_boot_aggregate(); /* boot aggregate must be first entry */
>> if (rc != 0)
>> return rc;
>> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
>> index 0e41dc1df1d4..719e88ca58f6 100644
>> --- a/security/integrity/ima/ima_queue.c
>> +++ b/security/integrity/ima/ima_queue.c
>> @@ -140,11 +140,15 @@ unsigned long ima_get_binary_runtime_size(void)
>> static int ima_pcr_extend(const u8 *hash, int pcr)
>> {
>> int result = 0;
>> + int i;
>>
>> if (!ima_tpm_chip)
>> return result;
>>
>> - result = tpm_pcr_extend(ima_tpm_chip, pcr, hash);
>> + for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++)
>> + memcpy(digests[i].digest, hash, TPM_DIGEST_SIZE);
>> +
>> + result = tpm_pcr_extend(ima_tpm_chip, pcr, digests);
>> if (result != 0)
>> pr_err("Error Communicating to TPM chip, result: %d\n", result);
>> return result;
>>
>

--
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Managing Director: Bo PENG, Jian LI, Yanli SHI

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