Re: [PATCH v9 6/6] tpm: pass an array of tpm_extend_digest structures to tpm_pcr_extend()

[Roberto Sassu]

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.

'digests' and ima_init_digests() can be moved to ima_queue.c, but I have
to add the definition of ima_init_digests() to ima.h. Should I do it?

  /* 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.

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.

Ok. Should I resend the last patch again with the fixes you suggested?

Thanks

Roberto

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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