libfscrypt: Options parser now fills missing defaults

Bug: 143307095
Test: use parser for fstab
Change-Id: Ia103a2e7947d03fb50a378472203363477d865e5

4 files changed, 176 insertions, 4 deletions

diff --git a/libfscrypt/fscrypt.cpp b/libfscrypt/fscrypt.cpp
index 8c578679..c29cf1e8 100644
--- a/libfscrypt/fscrypt.cpp
+++ b/libfscrypt/fscrypt.cpp
@@ -193,13 +193,35 @@ bool OptionsToString(const EncryptionOptions& options, std::string* options_stri
         return false;
     }
     *options_string = contents_mode + ":" + filenames_mode + ":v" + std::to_string(options.version);
+    EncryptionOptions options_check;
+    if (!ParseOptions(*options_string, &options_check)) {
+        LOG(ERROR) << "Internal error serializing options as string: " << *options_string;
+        return false;
+    }
+    if (memcmp(&options, &options_check, sizeof(options_check)) != 0) {
+        LOG(ERROR) << "Internal error serializing options as string, round trip failed: "
+                   << *options_string;
+        return false;
+    }
     return true;
 }
 
 bool ParseOptions(const std::string& options_string, EncryptionOptions* options) {
+    memset(options, '\0', sizeof(*options));
     auto parts = android::base::Split(options_string, ":");
-
-    if (parts.size() != 3) return false;
+    if (parts.size() < 1 || parts.size() > 3) {
+        return false;
+    }
+    if (parts.size() < 2) {
+        if (parts[0] == "adiantum") {
+            parts.emplace_back("adiantum");
+        } else {
+            parts.emplace_back("aes-256-cts");
+        }
+    }
+    if (parts.size() < 3) {
+        parts.emplace_back("v1");
+    }
 
     return ParseOptionsParts(parts[0], parts[1], parts[2], options);
 }
diff --git a/libfscrypt/include/fscrypt/fscrypt.h b/libfscrypt/include/fscrypt/fscrypt.h
index 29617ad5..ccd716f2 100644
--- a/libfscrypt/include/fscrypt/fscrypt.h
+++ b/libfscrypt/include/fscrypt/fscrypt.h
@@ -46,8 +46,6 @@ void BytesToHex(const std::string& bytes, std::string* hex);
 
 bool OptionsToString(const EncryptionOptions& options, std::string* options_string);
 
-// Note that right now this parses only the output from OptionsToString, not the
-// more general format that appears in fstabs.
 bool ParseOptions(const std::string& options_string, EncryptionOptions* options);
 
 bool ParseOptionsParts(const std::string& contents_mode, const std::string& filenames_mode,
diff --git a/libfscrypt/tests/Android.bp b/libfscrypt/tests/Android.bp
new file mode 100644
index 00000000..985b425f
--- /dev/null
+++ b/libfscrypt/tests/Android.bp
@@ -0,0 +1,33 @@
+// Copyright (C) 2019 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.
+
+cc_test {
+    name: "libfscrypt_unit_test",
+
+    shared_libs: [
+        "libbase",
+    ],
+    static_libs: [
+        "libfscrypt",
+    ],
+    srcs: [
+        "fscrypt_test.cpp",
+    ],
+
+    cflags: [
+        "-Wall",
+        "-Wextra",
+        "-Werror",
+    ],
+}
diff --git a/libfscrypt/tests/fscrypt_test.cpp b/libfscrypt/tests/fscrypt_test.cpp
new file mode 100644
index 00000000..13a37b76
--- /dev/null
+++ b/libfscrypt/tests/fscrypt_test.cpp
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2019 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 <linux/fs.h>
+
+#include <fscrypt/fscrypt.h>
+
+#include <gtest/gtest.h>
+
+using namespace android::fscrypt;
+
+/* modes not supported by upstream kernel, so not in <linux/fs.h> */
+#define FS_ENCRYPTION_MODE_AES_256_HEH 126
+#define FS_ENCRYPTION_MODE_PRIVATE 127
+
+TEST(fscrypt, ParseOptions) {
+    EncryptionOptions options;
+    std::string options_string;
+
+    EXPECT_FALSE(ParseOptions("", &options));
+    EXPECT_FALSE(ParseOptions("blah", &options));
+
+    EXPECT_TRUE(ParseOptions("software", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_XTS, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("aes-256-xts:aes-256-cts:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("aes-256-xts", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_XTS, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("aes-256-xts:aes-256-cts:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("adiantum", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_ADIANTUM, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_ADIANTUM, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("adiantum:adiantum:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("adiantum:aes-256-heh", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_ADIANTUM, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_HEH, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("adiantum:aes-256-heh:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("ice", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_PRIVATE, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("ice:aes-256-cts:v1", options_string);
+
+    EXPECT_FALSE(ParseOptions("ice:blah", &options));
+
+    EXPECT_TRUE(ParseOptions("ice:aes-256-cts", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_PRIVATE, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("ice:aes-256-cts:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("ice:aes-256-heh", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_PRIVATE, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_HEH, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("ice:aes-256-heh:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("ice:adiantum", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_PRIVATE, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_ADIANTUM, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("ice:adiantum:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("aes-256-xts:aes-256-cts", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_XTS, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("aes-256-xts:aes-256-cts:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("aes-256-xts:aes-256-cts:v1", &options));
+    EXPECT_EQ(1, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_XTS, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("aes-256-xts:aes-256-cts:v1", options_string);
+
+    EXPECT_TRUE(ParseOptions("aes-256-xts:aes-256-cts:v2", &options));
+    EXPECT_EQ(2, options.version);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_XTS, options.contents_mode);
+    EXPECT_EQ(FS_ENCRYPTION_MODE_AES_256_CTS, options.filenames_mode);
+    EXPECT_TRUE(OptionsToString(options, &options_string));
+    EXPECT_EQ("aes-256-xts:aes-256-cts:v2", options_string);
+
+    EXPECT_FALSE(ParseOptions("aes-256-xts:aes-256-cts:v2:", &options));
+    EXPECT_FALSE(ParseOptions("aes-256-xts:aes-256-cts:v2:foo", &options));
+    EXPECT_FALSE(ParseOptions("aes-256-xts:aes-256-cts:blah", &options));
+    EXPECT_FALSE(ParseOptions("aes-256-xts:aes-256-cts:vblah", &options));
+}