Refactor the TPM2_GetNonce to support a non-locking version for internal use. This avoids all possible recursive mutex calls.

examples/run_examples.sh

@@ -378,7 +378,7 @@ run_tpm_tls_client() { # Usage: run_tpm_tls_client [ecc/rsa] [tpmargs] [tlsversi
     generate_port
     pushd $WOLFSSL_PATH >> $TPMPWD/run.out 2>&1
     echo -e "./examples/server/server -v $3 -p $port -w -g -A ./certs/tpm-ca-$1-cert.pem"
-    ./examples/server/server -p $port -w -g -A ./certs/tpm-ca-$1-cert.pem &> $TPMPWD/run.out &
+    ./examples/server/server -p $port -w -g -A ./certs/tpm-ca-$1-cert.pem >> $TPMPWD/run.out 2>&1 &
     RESULT=$?
     [ $RESULT -ne 0 ] && echo -e "tls server $1 $2 failed! $RESULT" && exit 1
     popd >> $TPMPWD/run.out 2>&1

src/tpm2.c

@@ -163,7 +163,7 @@ static int TPM2_CommandProcess(TPM2_CTX* ctx, TPM2_Packet* packet,
 
         if (session->sessionHandle != TPM_RS_PW) {
             /* Generate fresh nonce */
-            rc = TPM2_GetNonce(session->nonceCaller.buffer,
+            rc = TPM2_GetNonceNoLock(session->nonceCaller.buffer,
                 session->nonceCaller.size);
             if (rc != TPM_RC_SUCCESS) {
                 return rc;
@@ -5689,9 +5689,7 @@ int TPM2_GetHashType(TPMI_ALG_HASH hashAlg)
     return 0;
 }
 
-/* Can optionally define WOLFTPM2_USE_HW_RNG to force using TPM hardware for
+int TPM2_GetNonceNoLock(byte* nonceBuf, int nonceSz)
- * RNG source */
-int TPM2_GetNonce(byte* nonceBuf, int nonceSz)
 {
     int rc;
     TPM2_CTX* ctx = TPM2_GetActiveCtx();
@@ -5720,44 +5718,58 @@ int TPM2_GetNonce(byte* nonceBuf, int nonceSz)
 #else
     /* Call GetRandom directly, so a custom packet buffer can be used.
      * This won't conflict when being called from TPM2_CommandProcess. */
-    rc = TPM2_AcquireLock(ctx);
+    while (randSz < nonceSz) {
-    if (rc == TPM_RC_SUCCESS) {
+        UINT16 inSz = nonceSz - randSz, outSz = 0;
-        while (randSz < nonceSz) {
+        if (inSz > MAX_RNG_REQ_SIZE) {
-            UINT16 inSz = nonceSz - randSz, outSz = 0;
+            inSz = MAX_RNG_REQ_SIZE;
-            if (inSz > MAX_RNG_REQ_SIZE) {
-                inSz = MAX_RNG_REQ_SIZE;
-            }
-
-            TPM2_Packet_InitBuf(&packet, buffer, (int)sizeof(buffer));
-            TPM2_Packet_AppendU16(&packet, inSz);
-            TPM2_Packet_Finalize(&packet, TPM_ST_NO_SESSIONS, TPM_CC_GetRandom);
-            rc = TPM2_SendCommand(ctx, &packet);
-        #ifdef WOLFTPM_DEBUG_VERBOSE
-            printf("TPM2_GetNonce (%d bytes at %d): %d (%s)\n",
-                inSz, randSz, rc, TPM2_GetRCString(rc));
-        #endif
-            if (rc != TPM_RC_SUCCESS) {
-                break;
-            }
-
-            TPM2_Packet_ParseU16(&packet, &outSz);
-            if (outSz > MAX_RNG_REQ_SIZE) {
-            #ifdef DEBUG_WOLFTPM
-                printf("TPM2_GetNonce out size error\n");
-            #endif
-                rc = BAD_FUNC_ARG;
-                break;
-            }
-            TPM2_Packet_ParseBytes(&packet, &nonceBuf[randSz], outSz);
-            randSz += outSz;
         }
-        TPM2_ReleaseLock(ctx);
+
+        TPM2_Packet_InitBuf(&packet, buffer, (int)sizeof(buffer));
+        TPM2_Packet_AppendU16(&packet, inSz);
+        TPM2_Packet_Finalize(&packet, TPM_ST_NO_SESSIONS, TPM_CC_GetRandom);
+        rc = TPM2_SendCommand(ctx, &packet);
+    #ifdef WOLFTPM_DEBUG_VERBOSE
+        printf("TPM2_GetNonce (%d bytes at %d): %d (%s)\n",
+            inSz, randSz, rc, TPM2_GetRCString(rc));
+    #endif
+        if (rc != TPM_RC_SUCCESS) {
+            break;
+        }
+
+        TPM2_Packet_ParseU16(&packet, &outSz);
+        if (outSz > MAX_RNG_REQ_SIZE) {
+        #ifdef DEBUG_WOLFTPM
+            printf("TPM2_GetNonce out size error\n");
+        #endif
+            rc = BAD_FUNC_ARG;
+            break;
+        }
+        TPM2_Packet_ParseBytes(&packet, &nonceBuf[randSz], outSz);
+        randSz += outSz;
     }
 #endif
 
     return rc;
 }
 
+int TPM2_GetNonce(byte* nonceBuf, int nonceSz)
+{
+    int rc;
+    TPM2_CTX* ctx = TPM2_GetActiveCtx();
+
+    if (ctx == NULL) {
+        return BAD_FUNC_ARG;
+    }
+
+    rc = TPM2_AcquireLock(ctx);
+    if (rc == TPM_RC_SUCCESS) {
+        rc = TPM2_GetNonceNoLock(nonceBuf, nonceSz);
+        TPM2_ReleaseLock(ctx);
+    }
+
+    return rc;
+}
+
 /* Get name for object/handle */
 int TPM2_GetName(TPM2_CTX* ctx, UINT32 handleValue, int handleCnt, int idx, TPM2B_NAME* name)
 {

src/tpm2_wrap.c

@@ -1592,7 +1592,7 @@ int wolfTPM2_StartSession(WOLFTPM2_DEV* dev, WOLFTPM2_SESSION* session,
         authSesIn.symmetric.algorithm = TPM_ALG_NULL;
     }
     authSesIn.nonceCaller.size = hashDigestSz;
-    rc = TPM2_GetNonce(authSesIn.nonceCaller.buffer,
+    rc = TPM2_GetNonceNoLock(authSesIn.nonceCaller.buffer,
                        authSesIn.nonceCaller.size);
     if (rc < 0) {
     #ifdef DEBUG_WOLFTPM
@@ -1604,7 +1604,7 @@ int wolfTPM2_StartSession(WOLFTPM2_DEV* dev, WOLFTPM2_SESSION* session,
     if (authSesIn.tpmKey != TPM_RH_NULL) {
         /* Generate random salt */
         session->salt.size = hashDigestSz;
-        rc = TPM2_GetNonce(session->salt.buffer, session->salt.size);
+        rc = TPM2_GetNonceNoLock(session->salt.buffer, session->salt.size);
         if (rc != 0) {
             return rc;
         }
@@ -2481,6 +2481,7 @@ int wolfTPM2_ImportRsaPrivateKeySeed(WOLFTPM2_DEV* dev,
     TPMI_ALG_RSA_SCHEME scheme, TPMI_ALG_HASH hashAlg, TPMA_OBJECT attributes,
     byte* seed, word32 seedSz)
 {
+    int rc = 0;
     TPM2B_PUBLIC pub;
     TPM2B_SENSITIVE sens;
     word32 digestSz;
@@ -2544,11 +2545,13 @@ int wolfTPM2_ImportRsaPrivateKeySeed(WOLFTPM2_DEV* dev,
     else {
         /* assign random seed */
         sens.sensitiveArea.seedValue.size = digestSz;
-        TPM2_GetNonce(sens.sensitiveArea.seedValue.buffer,
+        rc = TPM2_GetNonceNoLock(sens.sensitiveArea.seedValue.buffer,
             sens.sensitiveArea.seedValue.size);
     }
-
+    if (rc == 0) {
-    return wolfTPM2_ImportPrivateKey(dev, parentKey, keyBlob, &pub, &sens);
+        rc = wolfTPM2_ImportPrivateKey(dev, parentKey, keyBlob, &pub, &sens);
+    }
+    return rc;
 }
 int wolfTPM2_ImportRsaPrivateKey(WOLFTPM2_DEV* dev,
     const WOLFTPM2_KEY* parentKey, WOLFTPM2_KEYBLOB* keyBlob, const byte* rsaPub,
@@ -2633,6 +2636,7 @@ int wolfTPM2_ImportEccPrivateKeySeed(WOLFTPM2_DEV* dev, const WOLFTPM2_KEY* pare
     const byte* eccPriv, word32 eccPrivSz,
     TPMA_OBJECT attributes, byte* seed, word32 seedSz)
 {
+    int rc = 0;
     TPM2B_PUBLIC pub;
     TPM2B_SENSITIVE sens;
     word32 digestSz;
@@ -2696,11 +2700,14 @@ int wolfTPM2_ImportEccPrivateKeySeed(WOLFTPM2_DEV* dev, const WOLFTPM2_KEY* pare
     else {
         /* assign random seed */
         sens.sensitiveArea.seedValue.size = digestSz;
-        TPM2_GetNonce(sens.sensitiveArea.seedValue.buffer,
+        rc = TPM2_GetNonceNoLock(sens.sensitiveArea.seedValue.buffer,
             sens.sensitiveArea.seedValue.size);
     }
 
-    return wolfTPM2_ImportPrivateKey(dev, parentKey, keyBlob, &pub, &sens);
+    if (rc == 0) {
+        rc = wolfTPM2_ImportPrivateKey(dev, parentKey, keyBlob, &pub, &sens);
+    }
+    return rc;
 }
 
 int wolfTPM2_ImportEccPrivateKey(WOLFTPM2_DEV* dev, const WOLFTPM2_KEY* parentKey,
@@ -3234,13 +3241,14 @@ int wolfTPM2_ImportPrivateKeyBuffer(WOLFTPM2_DEV* dev,
         else {
             /* assign random seed */
             sens.sensitiveArea.seedValue.size = digestSz;
-            TPM2_GetNonce(sens.sensitiveArea.seedValue.buffer,
+            rc = TPM2_GetNonceNoLock(sens.sensitiveArea.seedValue.buffer,
                 sens.sensitiveArea.seedValue.size);
         }
 
-
+        if (rc == 0) {
-        /* Import Private Key */
+            /* Import Private Key */
-        rc = wolfTPM2_ImportPrivateKey(dev, parentKey, keyBlob, pub, &sens);
+            rc = wolfTPM2_ImportPrivateKey(dev, parentKey, keyBlob, pub, &sens);
+        }
     }
 
 #ifdef WOLFTPM2_PEM_DECODE
@@ -5776,7 +5784,7 @@ int wolfTPM2_ChangeHierarchyAuth(WOLFTPM2_DEV* dev, WOLFTPM2_SESSION* session,
         }
     }
     if (rc == 0) {
-        rc = TPM2_GetNonce(in.newAuth.buffer, in.newAuth.size);
+        rc = TPM2_GetNonceNoLock(in.newAuth.buffer, in.newAuth.size);
     }
     if (rc == 0) {
         rc = TPM2_HierarchyChangeAuth(&in);

wolftpm/tpm2.h

@@ -3434,7 +3434,9 @@ WOLFTPM_API TPMI_ALG_HASH TPM2_GetTpmHashType(int hashType);
 /*!
     \ingroup TPM2_Proprietary
     \brief Generate a fresh nonce of random numbers
-    \note Can use the TPM random number generator if WOLFTPM2_USE_HW_RNG is defined
+    \note Can use the TPM random number generator if WOLFTPM2_USE_HW_RNG is defined.
+        To force use of the TPM's RNG use WOLFTPM2_USE_HW_RNG. Please make sure you
+        have parameter encryption enabled to protect the RNG data over the bus.
 
     \return TPM_RC_SUCCESS: successful
     \return TPM_RC_FAILURE: generic failure (TPM IO issue or wolfcrypt configuration)
@@ -3456,6 +3458,9 @@ WOLFTPM_API TPMI_ALG_HASH TPM2_GetTpmHashType(int hashType);
 */
 WOLFTPM_API int TPM2_GetNonce(byte* nonceBuf, int nonceSz);
 
+/* Internal API for getting nonce without taking lock */
+WOLFTPM_LOCAL int TPM2_GetNonceNoLock(byte* nonceBuf, int nonceSz);
+
 /*!
     \ingroup TPM2_Proprietary
     \brief Helper function to prepare a correct PCR selection