tpm: setup "get pcr" callback on policy execution

It's a calculation callback, but not yet calculated policy is automatically calculated before execution. Signed-off-by: Sergii Dmytruk <[email protected]>
tpm2-software · Apr 3, 2023 · bccb707 · bccb707
1 parent 03e9dd3
commit bccb707
Showing 1 changed file with 59 additions and 0 deletions.
diff --git a/src/lib/tpm.c b/src/lib/tpm.c
@@ -4012,6 +4012,55 @@ CK_RV tpm2_getmechanisms(tpm_ctx *ctx, CK_MECHANISM_TYPE *mechanism_list, CK_ULO
 }
 
 #ifdef HAVE_POLICY
+static TSS2_RC tpm2_policy_get_pcr(TSS2_POLICY_PCR_SELECTION *selection,
+        TPML_PCR_SELECTION *out_selection,
+        TPML_DIGEST *out_digest,
+        void *userdata)
+{
+
+    TPML_PCR_SELECTION in_pcr_selection = {0};
+    if (selection->type == TSS2_POLICY_PCR_SELECTOR_PCR_SELECTION) {
+        in_pcr_selection = selection->selections.pcr_selection;
+    } else {
+        in_pcr_selection.count = 1;
+
+        TPMS_PCR_SELECTION *pcr_bank = &in_pcr_selection.pcrSelections[0];
+        TPMS_PCR_SELECT *pcr_select = &selection->selections.pcr_select;
+
+        pcr_bank->hash = TPM2_ALG_SHA256;
+        pcr_bank->sizeofSelect = pcr_select->sizeofSelect;
+        memcpy(pcr_bank->pcrSelect, pcr_select->pcrSelect, pcr_bank->sizeofSelect);
+    }
+
+    ESYS_CONTEXT *esys_ctx = userdata;
+
+    UINT32 pcr_update_counter;
+    TPML_PCR_SELECTION *pcr_selection = NULL;
+    TPML_DIGEST *pcr_values = NULL;
+
+    TSS2_RC rc = Esys_PCR_Read(esys_ctx,
+                 ESYS_TR_NONE,
+                 ESYS_TR_NONE,
+                 ESYS_TR_NONE,
+                 &in_pcr_selection,
+                 &pcr_update_counter,
+                 &pcr_selection,
+                 &pcr_values);
+    if (rc != TSS2_RC_SUCCESS) {
+        LOGE("Esys_PCR_Read: %s:", Tss2_RC_Decode(rc));
+        free(pcr_selection);
+        free(pcr_values);
+        return rc;
+    }
+
+    *out_selection = *pcr_selection;
+    *out_digest = *pcr_values;
+
+    free(pcr_selection);
+    free(pcr_values);
+    return TSS2_RC_SUCCESS;
+}
+
 CK_RV tpm2_execute_policy(tpm_ctx *ctx, TSS2_POLICY_CTX *policy_ctx, uint32_t handle)
 {
 
@@ -4025,8 +4074,18 @@ CK_RV tpm2_execute_policy(tpm_ctx *ctx, TSS2_POLICY_CTX *policy_ctx, uint32_t ha
         .mode = { .aes = TPM2_ALG_CFB }
     };
 
+    TSS2_POLICY_CALC_CALLBACKS calc_callbacks = {0};
+    calc_callbacks.cbpcr = &tpm2_policy_get_pcr;
+    calc_callbacks.cbpcr_userdata = ctx->esys_ctx;
+
     TSS2_RC rc;
 
+    rc = Tss2_PolicySetCalcCallbacks(policy_ctx, &calc_callbacks);
+    if (rc != TSS2_RC_SUCCESS) {
+        LOGE("Tss2_PolicySetCalcCallbacks: %s:", Tss2_RC_Decode(rc));
+        return CKR_GENERAL_ERROR;
+    }
+
     /* XXX should we cache the session or running multiple policies is unlikely? */
     ESYS_TR policy_session = ESYS_TR_NONE;
     rc = Esys_StartAuthSession(ctx->esys_ctx,