Isolate crypto implementation details.

am: 495f9ee739

Change-Id: Ib218e4d5fcf4a2b0e0e4dfcc1c24c8795a63afe6

7 files changed, 125 insertions, 27 deletions

diff --git a/core/Android.mk b/core/Android.mk
index 7eefb48..4da770c 100644
--- a/core/Android.mk
+++ b/core/Android.mk
@@ -19,27 +19,27 @@ LOCAL_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 LOCAL_MODULE := libnvram-core
 LOCAL_SRC_FILES := \
+	crypto_boringssl.cpp \
 	nvram_manager.cpp \
 	persistence.cpp
 LOCAL_CFLAGS := -Wall -Werror -Wextra
 LOCAL_CLANG := true
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES := libconstrainedcrypto
-LOCAL_SHARED_LIBRARIES := libnvram-messages
+LOCAL_SHARED_LIBRARIES := libnvram-messages libcrypto
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := libnvram-core-host
 LOCAL_SRC_FILES := \
+	crypto_boringssl.cpp \
 	nvram_manager.cpp \
 	persistence.cpp
 LOCAL_CFLAGS := -Wall -Werror -Wextra
 LOCAL_CLANG := true
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
-LOCAL_STATIC_LIBRARIES := libconstrainedcrypto
-LOCAL_SHARED_LIBRARIES := libnvram-messages-host
+LOCAL_SHARED_LIBRARIES := libnvram-messages-host libcrypto-host
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 include $(call all-makefiles-under,$(LOCAL_PATH))
diff --git a/core/crypto.h b/core/crypto.h
new file mode 100644
index 0000000..b97fb17
--- /dev/null
+++ b/core/crypto.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef NVRAM_CORE_CRYPTO_H_
+#define NVRAM_CORE_CRYPTO_H_
+
+extern "C" {
+#include <stddef.h>
+#include <stdint.h>
+}  // extern "C"
+
+namespace nvram {
+namespace crypto {
+
+// Size of a SHA-256 digest in bytes.
+constexpr size_t kSHA256DigestSize = 32;
+
+// Computes the SHA-256 digest of the |data_size| input bytes stored at |data|.
+// The digest is written to |digest|, which is a buffer of size |digest_size|.
+// Note that |digest_size| doesn't have to match SHA-256's output size of 32
+// bytes. If it doesn't the digest is truncated or zero-padded as necessary.
+//
+// Returns true if the digest was computed successfully, false otherwise.
+void SHA256(const uint8_t* data,
+            size_t data_size,
+            uint8_t* digest,
+            size_t digest_size);
+
+}  // namespace crypto
+}  // namespave nvram
+
+#endif  // NVRAM_CORE_CRYPTO_H_
diff --git a/core/crypto_boringssl.cpp b/core/crypto_boringssl.cpp
new file mode 100644
index 0000000..23897b5
--- /dev/null
+++ b/core/crypto_boringssl.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "crypto.h"
+
+extern "C" {
+#include <string.h>
+
+#include <openssl/mem.h>
+#include <openssl/sha.h>
+}  // extern "C"
+
+namespace nvram {
+namespace crypto {
+
+void SHA256(const uint8_t* data,
+            size_t data_size,
+            uint8_t* digest,
+            size_t digest_size) {
+  // SHA256 requires an output buffer of at least SHA256_DIGEST_LENGTH.
+  // |digest_size| might be less, so store the digest in a local buffer.
+  uint8_t buffer[SHA256_DIGEST_LENGTH];
+  ::SHA256(data, data_size, buffer);
+
+  // Copy the result to |digest|.
+  if (digest_size < sizeof(buffer)) {
+    memcpy(digest, buffer, digest_size);
+  } else {
+    memcpy(digest, buffer, sizeof(buffer));
+    memset(digest + sizeof(buffer), 0, digest_size - sizeof(buffer));
+  }
+}
+
+}  // namespace crypto
+}  // namespace nvram
diff --git a/core/nvram_manager.cpp b/core/nvram_manager.cpp
index d5aee05..a1eb9c1 100644
--- a/core/nvram_manager.cpp
+++ b/core/nvram_manager.cpp
@@ -21,9 +21,10 @@ extern "C" {
 #include <string.h>
 }  // extern "C"
 
-#include <constrainedcrypto/sha256.h>
 #include <nvram/core/logger.h>
 
+#include "crypto.h"
+
 using namespace nvram::storage;
 
 namespace nvram {
@@ -211,8 +212,9 @@ nvram_result_t NvramManager::CreateSpace(const CreateSpaceRequest& request,
     return NV_RESULT_INVALID_PARAMETER;
   }
   if ((controls & (1 << NV_CONTROL_WRITE_EXTEND)) != 0 &&
-      request.size != SHA256_DIGEST_SIZE) {
-    NVRAM_LOG_INFO("Write-extended space size must be %d.", SHA256_DIGEST_SIZE);
+      request.size != crypto::kSHA256DigestSize) {
+    NVRAM_LOG_INFO("Write-extended space size must be %zu.",
+                   crypto::kSHA256DigestSize);
     return NV_RESULT_INVALID_PARAMETER;
   }
 
@@ -385,22 +387,18 @@ nvram_result_t NvramManager::WriteSpace(const WriteSpaceRequest& request,
 
   Blob& contents = space_record.persistent.contents;
   if (space_record.persistent.HasControl(NV_CONTROL_WRITE_EXTEND)) {
-    // Compute the hash of existing contents concatenated with input.
-    SHA256_CTX sha256_context;
-    SHA256_init(&sha256_context);
-    SHA256_update(&sha256_context, contents.data(), contents.size());
-    SHA256_update(&sha256_context, request.buffer.data(),
-                  request.buffer.size());
-
-    // Make sure to handle both short and long space sizes gracefully,
-    // truncating or extending with 0 bytes as necessary. Even though
-    // |CreateSpace()| rejects |NV_CONTROL_WRITE_EXTEND| spaces that are not of
-    // size |SHA256_DIGEST_SIZE|, it's better to avoid any assumptions about
-    // data read from storage.
-    size_t hash_size =
-        min(contents.size(), static_cast<size_t>(SHA256_DIGEST_SIZE));
-    memcpy(contents.data(), SHA256_final(&sha256_context), hash_size);
-    memset(contents.data() + hash_size, 0x0, contents.size() - hash_size);
+    // Concatenate the current space |contents| with the input data.
+    Blob sha256_input;
+    if (!sha256_input.Resize(contents.size() + request.buffer.size())) {
+      return NV_RESULT_INTERNAL_ERROR;
+    }
+    memcpy(sha256_input.data(), contents.data(), contents.size());
+    memcpy(sha256_input.data() + contents.size(), request.buffer.data(),
+           request.buffer.size());
+
+    // Compute the SHA-256 digest and write it back to |contents|.
+    crypto::SHA256(sha256_input.data(), sha256_input.size(), contents.data(),
+                   contents.size());
   } else {
     if (contents.size() < request.buffer.size()) {
       return NV_RESULT_INVALID_PARAMETER;
diff --git a/core/rules.mk b/core/rules.mk
index c53a2e6..ed2f0a4 100644
--- a/core/rules.mk
+++ b/core/rules.mk
@@ -22,12 +22,14 @@ LOCAL_DIR := $(GET_LOCAL_DIR)
 MODULE := $(LOCAL_DIR)
 
 MODULE_SRCS += \
+	$(LOCAL_DIR)/crypto_boringssl.cpp \
 	$(LOCAL_DIR)/nvram_manager.cpp \
 	$(LOCAL_DIR)/persistence.cpp
 
 MODULE_CPPFLAGS := -Wall -Werror -Wextra -std=c++11
 
 MODULE_DEPS += \
+	external/openssl \
 	lib/libc-trusty \
 	lib/libstdc++-trusty \
 	system/nvram/messages
diff --git a/core/tests/Android.mk b/core/tests/Android.mk
index ed956ba..003bfdf 100644
--- a/core/tests/Android.mk
+++ b/core/tests/Android.mk
@@ -24,6 +24,6 @@ LOCAL_SRC_FILES := \
 	nvram_manager_test.cpp
 LOCAL_CFLAGS := -Wall -Werror -Wextra -DHAS_GTEST
 LOCAL_CLANG := true
-LOCAL_STATIC_LIBRARIES := libnvram-core-host libconstrainedcrypto
-LOCAL_SHARED_LIBRARIES := libnvram-messages-host
+LOCAL_STATIC_LIBRARIES := libnvram-core-host
+LOCAL_SHARED_LIBRARIES := libnvram-messages-host libcrypto-host
 include $(BUILD_HOST_NATIVE_TEST)
diff --git a/hal/Android.mk b/hal/Android.mk
index b23c9a9..6f8a753 100644
--- a/hal/Android.mk
+++ b/hal/Android.mk
@@ -55,8 +55,13 @@ LOCAL_SRC_FILES := \
 	fake_nvram_storage.cpp
 LOCAL_CLANG := true
 LOCAL_CFLAGS := -Wall -Werror -Wextra
-LOCAL_STATIC_LIBRARIES := libnvram-core libconstrainedcrypto
-LOCAL_SHARED_LIBRARIES := libnvram-messages libminijail libcutils libbase
+LOCAL_STATIC_LIBRARIES := libnvram-core
+LOCAL_SHARED_LIBRARIES := \
+	libnvram-messages \
+	libcrypto \
+	libminijail \
+	libcutils \
+	libbase
 LOCAL_INIT_RC := fake-nvram.rc
 LOCAL_REQUIRED_MODULES := fake-nvram-seccomp.policy
 LOCAL_MODULE_TAGS := optional