swtpm: Return TPM_FAIL if SWTPM_NVRAM_DecrytpData is called without key

[swtpm.git] / src / swtpm / swtpm_nvstore.c

diff --git a/src/swtpm/swtpm_nvstore.c b/src/swtpm/swtpm_nvstore.c
index 953d6bb09792c32bd0dea25c236f642f83154f0c..ff5cb80afa55e610f4a4e6278343770e1fab3e5d 100644 (file)
--- a/src/swtpm/swtpm_nvstore.c
+++ b/src/swtpm/swtpm_nvstore.c
@@ -886,7 +886,7 @@ SWTPM_NVRAM_DecryptData(const encryptionkey *key,
                         uint16_t tag_ivec, uint16_t hdrflags,
                         uint16_t flag_256bitkey)
 {
-    TPM_RESULT rc = 0;
+    TPM_RESULT rc = TPM_FAIL;
     unsigned char *tmp_data = NULL;
     uint32_t tmp_length = 0;
     tlv_data td[2];
@@ -894,63 +894,62 @@ SWTPM_NVRAM_DecryptData(const encryptionkey *key,
     uint32_t ivec_length = 0;
     size_t keylen;
 
-    if (key->symkey.userKeyLength > 0) {
-        switch (key->data_encmode) {
-        case ENCRYPTION_MODE_UNKNOWN:
-            rc = TPM_BAD_MODE;
-            break;
-        case ENCRYPTION_MODE_AES_CBC:
-            switch (hdrversion) {
-            case 1:
-                rc = SWTPM_SymmetricKeyData_Decrypt(&tmp_data,
-                                                    &tmp_length,
-                                                    data, length,
-                                                    &key->symkey,
-                                                    NULL, 0);
-                if (rc == 0) {
-                    rc = SWTPM_CheckHash(tmp_data, tmp_length,
-                                         decrypt_data, decrypt_length);
-                }
-            break;
-            case 2:
-                keylen = (hdrflags & flag_256bitkey)
-                          ? SWTPM_AES256_BLOCK_SIZE : SWTPM_AES128_BLOCK_SIZE;
-                if (keylen != key->symkey.userKeyLength) {
-                    logprintf(STDERR_FILENO,
-                              "Wrong decryption key. Need %zu bit key.\n",
-                              keylen * 8);
-                    rc = TPM_BAD_KEY_PROPERTY;
-                    break;
-                }
-
-                if (!tlv_data_find_tag(data, length, TAG_HMAC, &td[0]) ||
-                    !tlv_data_find_tag(data, length, tag_encrypted_data,
-                                       &td[1])) {
-                    logprintf(STDERR_FILENO,
-                              "Could not find HMAC or encrypted data (tag %u) "
-                              "in byte stream.\n", tag_encrypted_data);
-                    rc = TPM_FAIL;
-                    break;
-                }
-                /* get the IV, if there is one */
-                SWTPM_GetIvec(data, length, &ivec, &ivec_length, tag_ivec);
-
-                rc = SWTPM_CheckHMAC(&td[0], &td[1], &key->symkey,
-                                     ivec, ivec_length);
-                if (rc == 0) {
-                    rc = SWTPM_SymmetricKeyData_Decrypt(decrypt_data,
-                                                        decrypt_length,
-                                                        td[1].u.const_ptr,
-                                                        td[1].tlv.length,
-                                                        &key->symkey,
-                                                        ivec, ivec_length);
-                }
-            break;
-            default:
+    if (key->symkey.userKeyLength == 0)
+        return rc;
+
+    switch (key->data_encmode) {
+    case ENCRYPTION_MODE_UNKNOWN:
+        rc = TPM_BAD_MODE;
+        break;
+    case ENCRYPTION_MODE_AES_CBC:
+        switch (hdrversion) {
+        case 1:
+            rc = SWTPM_SymmetricKeyData_Decrypt(&tmp_data,
+                                                &tmp_length,
+                                                data, length,
+                                                &key->symkey,
+                                                NULL, 0);
+            if (rc == 0) {
+                rc = SWTPM_CheckHash(tmp_data, tmp_length,
+                                     decrypt_data, decrypt_length);
+            }
+        break;
+        case 2:
+            keylen = (hdrflags & flag_256bitkey)
+                      ? SWTPM_AES256_BLOCK_SIZE : SWTPM_AES128_BLOCK_SIZE;
+            if (keylen != key->symkey.userKeyLength) {
+                logprintf(STDERR_FILENO,
+                          "Wrong decryption key. Need %zu bit key.\n",
+                          keylen * 8);
+                rc = TPM_BAD_KEY_PROPERTY;
+                break;
+            }
+
+            if (!tlv_data_find_tag(data, length, TAG_HMAC, &td[0]) ||
+                !tlv_data_find_tag(data, length, tag_encrypted_data,
+                                   &td[1])) {
+                logprintf(STDERR_FILENO,
+                          "Could not find HMAC or encrypted data (tag %u) "
+                          "in byte stream.\n", tag_encrypted_data);
                 rc = TPM_FAIL;
+                break;
+            }
+            /* get the IV, if there is one */
+            SWTPM_GetIvec(data, length, &ivec, &ivec_length, tag_ivec);
+
+            rc = SWTPM_CheckHMAC(&td[0], &td[1], &key->symkey,
+                                 ivec, ivec_length);
+            if (rc == 0) {
+                rc = SWTPM_SymmetricKeyData_Decrypt(decrypt_data,
+                                                    decrypt_length,
+                                                    td[1].u.const_ptr,
+                                                    td[1].tlv.length,
+                                                    &key->symkey,
+                                                    ivec, ivec_length);
             }
-            free(tmp_data);
+        break;
         }
+        free(tmp_data);
     }
 
     return rc;