Let custom stores report records that did not commit

README.md

@@ -128,6 +128,16 @@ Enables debugging printf's for store.
 Removes default implementation of storage functions.
 See wolfpkcs11/store.h for prototypes of functions to implement.
 
+#### Define WOLFPKCS11_CUSTOM_STORE_CLOSE_COMMIT
+
+With `WOLFPKCS11_CUSTOM_STORE`, records that were written are closed with
+`wolfPKCS11_Store_CloseCommit()` instead of `wolfPKCS11_Store_Close()`, so the
+custom store must implement it too (`wolfPKCS11_Store_Close()` still closes
+records that were read). It returns non-zero when the record did not commit,
+for example when a flash write failed. wolfPKCS11 then fails the operation and
+writes all records of the token on its next store. Without this define, the
+custom store cannot report a failed commit.
+
 #### Define WOLFPKCS11_KEYPAIR_GEN_COMMON_LABEL
 
 Sets the private key's label against the public key when generating key pairs.

configure.ac

@@ -664,6 +664,15 @@ AX_HARDEN_CC_COMPILER_FLAGS
 
 OPTION_FLAGS="$CFLAGS $CPPFLAGS $AM_CFLAGS"
 
+# The custom store tests build the library with WOLFPKCS11_CUSTOM_STORE. NSS
+# needs the file store, and a custom store cannot be built with the TPM store.
+AS_CASE([" $OPTION_FLAGS "],
+    [*" -DWOLFPKCS11_NSS "*|*" -DWOLFPKCS11_TPM_STORE "*],
+    [ENABLED_CUSTOM_STORE_TEST=no],
+    [ENABLED_CUSTOM_STORE_TEST=yes])
+AM_CONDITIONAL([BUILD_CUSTOM_STORE_TEST],
+    [test "x$ENABLED_CUSTOM_STORE_TEST" = "xyes"])
+
 AS_IF([test "x$WOLFPKCS11_STATIC_WOLFSSL" = "xyes"],
       [WOLFPKCS11_CONFIG_LIBS="$LIBS -lm"
        LIBS="$STATIC_WOLFSSL $LIBS -lm"],

src/internal.c

@@ -2999,7 +2999,7 @@ static int wolfPKCS11_Store_TpmCommit(WP11_TpmStore* tpmStore)
  * @return  0 on success.
  * @return  Other value when written data could not be committed.
  */
-static int wolfPKCS11_Store_CloseCommit(void* store, int commit)
+int wolfPKCS11_Store_CloseCommit(void* store, int commit)
 {
     int ret = 0;
 #ifdef WOLFPKCS11_TPM_STORE
@@ -3220,6 +3220,24 @@ int wolfPKCS11_Store_Write(void* store, unsigned char* buffer, int len)
 }
 #endif
 
+#ifdef WOLFPKCS11_CUSTOM_STORE
+/*
+ * Maps a custom store's failure to open to BUFFER_E.
+ * The store's own code could otherwise read as another status, such as
+ * PIN_INVALID_E. NOT_AVAILABLE_E is kept: the data is not stored.
+ *
+ * @param [in]  ret  Result of opening.
+ * @return  0 or NOT_AVAILABLE_E as passed in.
+ * @return  BUFFER_E for any other failure.
+ */
+static int wp11_storage_open_ret(int ret)
+{
+    if (ret != 0 && ret != NOT_AVAILABLE_E)
+        ret = BUFFER_E;
+    return ret;
+}
+#endif
+
 /*
  * Opens access to location to read token data.
  *
@@ -3236,7 +3254,12 @@ int wolfPKCS11_Store_Write(void* store, unsigned char* buffer, int len)
 static int wp11_storage_open_readonly(int type, CK_ULONG id1, CK_ULONG id2,
                               void** storage)
 {
-    return wolfPKCS11_Store_Open(type, id1, id2, 1, storage);
+    int ret = wolfPKCS11_Store_Open(type, id1, id2, 1, storage);
+
+#ifdef WOLFPKCS11_CUSTOM_STORE
+    ret = wp11_storage_open_ret(ret);
+#endif
+    return ret;
 }
 
 /*
@@ -3257,8 +3280,14 @@ static int wp11_storage_open(int type, CK_ULONG id1, CK_ULONG id2,
 #ifdef WOLFPKCS11_TPM_STORE
     return wolfPKCS11_Store_OpenSz(type, id1, id2, 0, variableSz, storage);
 #else
+    int ret;
+
     (void)variableSz; /* not used */
-    return wolfPKCS11_Store_Open(type, id1, id2, 0, storage);
+    ret = wolfPKCS11_Store_Open(type, id1, id2, 0, storage);
+#ifdef WOLFPKCS11_CUSTOM_STORE
+    ret = wp11_storage_open_ret(ret);
+#endif
+    return ret;
 #endif
 }
 
@@ -3289,11 +3318,19 @@ static void wp11_storage_close(void* storage)
  */
 static int wp11_storage_close_write(void* storage, int ret)
 {
-#ifdef WOLFPKCS11_CUSTOM_STORE
+#if defined(WOLFPKCS11_CUSTOM_STORE) && \
+    !defined(WOLFPKCS11_CUSTOM_STORE_CLOSE_COMMIT)
+    /* The store cannot report a failed commit. */
     wolfPKCS11_Store_Close(storage);
 #else
     int closeRet = wolfPKCS11_Store_CloseCommit(storage, ret == 0);
 
+#ifdef WOLFPKCS11_CUSTOM_STORE
+    /* Any failure means the data did not commit. A custom store's code could
+     * otherwise read as NOT_AVAILABLE_E, which means storage is turned off. */
+    if (closeRet != 0)
+        closeRet = BUFFER_E;
+#endif
     if (ret == 0)
         ret = closeRet;
 #endif
@@ -3351,6 +3388,13 @@ static int wp11_storage_read(void* storage, unsigned char* buffer, int len)
         /* Failed to read all data. */
         ret = BUFFER_E;
     }
+#ifdef WOLFPKCS11_CUSTOM_STORE
+    else {
+        /* A custom store's failure code could otherwise read as another
+         * status, such as PIN_INVALID_E. */
+        ret = BUFFER_E;
+    }
+#endif
 
     return ret;
 }
@@ -3425,8 +3469,9 @@ static int wp11_storage_write(void* storage, unsigned char* buffer, int len)
         /* All written successfully. */
         ret = 0;
     }
-    else if (ret == 0) {
-        /* Failed to write all data. */
+    else {
+        /* Failed to write all data. A custom store's failure code could
+         * otherwise read as another status, such as PIN_INVALID_E. */
         ret = BUFFER_E;
     }
 
@@ -5007,7 +5052,9 @@ static int wp11_Object_Load_Data(WP11_Object* object, int tokenId, int objId)
             object->data.genericData.objectIdLen = (word32)tempLen;
     }
 
-    wp11_storage_close(storage);
+    /* Nothing to close when the open failed. */
+    if (storage != NULL)
+        wp11_storage_close(storage);
 
     return ret;
 }
@@ -5577,7 +5624,9 @@ static int wp11_Object_Store_Data(WP11_Object* object, int tokenId, int objId)
             object->data.genericData.objectIdLen);
     }
 
-    ret = wp11_storage_close_write(storage, ret);
+    /* Nothing to close when the open failed. */
+    if (storage != NULL)
+        ret = wp11_storage_close_write(storage, ret);
 
     return ret;
 }

tests/README.md

@@ -5,3 +5,6 @@ The test files have the following purposes:
 * `pkcs11mtt.c`: is the multithreaded tests
 * `pkcs11str.c`: is a storage test
 * `debug_test.c`: is a debug functionality demonstration test
+* `custom_store_test.c`: is a custom store (`WOLFPKCS11_CUSTOM_STORE`) test. It
+  builds the library sources in, with and without
+  `WOLFPKCS11_CUSTOM_STORE_CLOSE_COMMIT`