SERVER-41277 Create FLE Data Framing Classes

1 files changed, 191 insertions, 0 deletions

diff --git a/src/mongo/crypto/fle_data_frames.h b/src/mongo/crypto/fle_data_frames.h
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index 00000000000..a72b31dceb1
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+++ b/src/mongo/crypto/fle_data_frames.h
@@ -0,0 +1,191 @@
+/**
+ *    Copyright (C) 2019-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include "mongo/base/data_range.h"
+#include "mongo/crypto/symmetric_crypto.h"
+#include "mongo/db/matcher/schema/encrypt_schema_gen.h"
+#include "mongo/shell/kms_gen.h"
+#include "mongo/util/uuid.h"
+
+namespace mongo {
+constexpr int kAssociatedDataLength = 18;
+constexpr size_t kHmacOutSize = 32;
+
+/**
+ * Returns the length of the plaintext output given the ciphertext length. Only for AEAD.
+ */
+inline StatusWith<size_t> aeadGetMaximumPlainTextLength(size_t cipherTextLen) {
+    if (cipherTextLen > (crypto::aesCBCIVSize + kHmacOutSize)) {
+        return cipherTextLen - crypto::aesCBCIVSize - kHmacOutSize;
+    }
+
+    return Status(ErrorCodes::BadValue, "Invalid cipher text length");
+}
+
+/**
+ * This class is a helper for encryption. It holds a ConstDataRange over the
+ * plaintext to be encrypted and owns a buffer where the BinData subtype 6 is
+ * written out to. The encrypt function can only be called after the constructor
+ * to initialize the plaintext, the associated data, and the key has been called.
+ */
+class FLEEncryptionFrame {
+
+public:
+    FLEEncryptionFrame(std::shared_ptr<SymmetricKey> key,
+                       FleAlgorithmInt algorithm,
+                       UUID uuid,
+                       BSONType type,
+                       ConstDataRange plaintext,
+                       size_t cipherLength)
+        : _key(std::move(key)), _plaintext(plaintext) {
+        // As per the description of the encryption algorithm for FLE, the
+        // associated data is constructed of the following -
+        // associatedData[0] = the FleAlgorithmEnum
+        //      - either a 1 or a 2 depending on whether the iv is provided.
+        // associatedData[1-16] = the uuid in bytes
+        // associatedData[17] = the bson type
+        _data.resize(kAssociatedDataLength + cipherLength);
+        _data[0] = FleAlgorithmInt_serializer(algorithm);
+        auto uuidCDR = uuid.toCDR();
+        invariant(uuidCDR.length() == 16);
+        std::copy(
+            uuidCDR.data<uint8_t>(), uuidCDR.data<uint8_t>() + uuidCDR.length(), _data.begin() + 1);
+        _data[17] = static_cast<uint8_t>(type);
+    }
+
+    FLEEncryptionFrame() : _plaintext(ConstDataRange(nullptr, 0)){};
+
+    const ConstDataRange get() const& {
+        return ConstDataRange(_data);
+    }
+
+    std::shared_ptr<SymmetricKey> getKey() const {
+        return _key;
+    }
+
+    const ConstDataRange getPlaintext() const {
+        return _plaintext;
+    }
+
+    const ConstDataRange getAssociatedData() const {
+        return ConstDataRange(_data.data(), kAssociatedDataLength);
+    }
+
+    uint8_t* getCiphertextMutable() & {
+        invariant(_data.size() > kAssociatedDataLength);
+        return _data.data() + kAssociatedDataLength;
+    }
+
+    uint8_t* getCiphertextMutable() && = delete;
+
+    FleAlgorithmInt getFLEAlgorithmType() {
+        return FleAlgorithmInt_parse(IDLParserErrorContext("root"), _data[0]);
+    }
+
+    size_t getDataLength() const {
+        return _data.size() - kAssociatedDataLength;
+    }
+
+private:
+    std::shared_ptr<SymmetricKey> _key;
+    std::vector<uint8_t> _data;
+    ConstDataRange _plaintext;
+};
+
+/**
+ * This is a helper class for decryption. It has a ConstDataRange over a
+ * vector owned by the instantiator of this class and allows
+ * containing the plaintext object after it has been decrypted.
+ */
+class FLEDecryptionFrame {
+public:
+    FLEDecryptionFrame(ConstDataRange data) : _data(data) {
+        uassert(ErrorCodes::BadValue,
+                "Ciphertext blob too small",
+                _data.length() > kAssociatedDataLength);
+        uassert(ErrorCodes::BadValue,
+                "Ciphertext blob algorithm unknown",
+                (getFLEAlgorithmType() == FleAlgorithmInt::kDeterministic ||
+                 getFLEAlgorithmType() == FleAlgorithmInt::kRandom));
+
+        _plaintext.resize(
+            uassertStatusOK(aeadGetMaximumPlainTextLength(data.length() - kAssociatedDataLength)));
+    }
+
+    void setKey(std::shared_ptr<SymmetricKey> key) {
+        _key = key;
+    }
+
+    std::shared_ptr<SymmetricKey> getKey() {
+        return _key;
+    }
+
+    const ConstDataRange getAssociatedData() const {
+        return ConstDataRange(_data.data(), kAssociatedDataLength);
+    }
+
+    UUID getUUID() const {
+        auto uuid = UUID::fromCDR(ConstDataRange(_data.data() + 1, UUID::kNumBytes));
+        return uuid;
+    }
+
+    ConstDataRange getCiphertext() const {
+        return ConstDataRange(_data.data() + kAssociatedDataLength, getDataLength());
+    }
+
+    ConstDataRange getPlaintext() const {
+        return ConstDataRange(_plaintext);
+    }
+
+    std::vector<uint8_t>& getPlaintextMutable() {
+        return _plaintext;
+    }
+
+    uint8_t getBSONType() {
+        return *(_data.data<uint8_t>() + 17);
+    }
+
+private:
+    FleAlgorithmInt getFLEAlgorithmType() const {
+        return FleAlgorithmInt_parse(IDLParserErrorContext("root"), *_data.data<uint8_t>());
+    }
+
+    size_t getDataLength() const {
+        return _data.length() - kAssociatedDataLength;
+    }
+
+
+    std::shared_ptr<SymmetricKey> _key;
+    ConstDataRange _data;
+    std::vector<uint8_t> _plaintext;
+};
+
+}  // namespace mongo