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/**
* Copyright (C) 2022-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 <memory>
#include "boost/smart_ptr/intrusive_ptr.hpp"
#include "mongo/bson/bsonobj.h"
#include "mongo/crypto/fle_crypto.h"
#include "mongo/db/fle_crud.h"
#include "mongo/db/matcher/expression_parser.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/transaction_api.h"
namespace mongo {
class FLEQueryInterface;
namespace fle {
/**
* Process a find command with encryptionInformation in-place, rewriting the filter condition so
* that any query on an encrypted field will properly query the underlying tags array.
*/
void processFindCommand(OperationContext* opCtx,
FindCommandRequest* findCommand,
GetTxnCallback txn);
/**
* Process a pipeline with encryptionInformation by rewriting the pipeline to query against the
* underlying tags array, where appropriate. After this rewriting is complete, there is no more FLE
* work to be done. The encryption info does not need to be kept around (e.g. on a command object).
*/
std::unique_ptr<Pipeline, PipelineDeleter> processPipeline(
OperationContext* opCtx,
NamespaceString nss,
const EncryptionInformation& encryptInfo,
std::unique_ptr<Pipeline, PipelineDeleter> toRewrite);
/**
* Rewrite a filter MatchExpression with FLE Find Payloads into a disjunction over the tag array
* from inside an existing transaction using a FLEQueryInterface constructed from a
* transaction client.
*/
BSONObj rewriteEncryptedFilterInsideTxn(FLEQueryInterface* queryImpl,
StringData db,
const EncryptedFieldConfig& efc,
boost::intrusive_ptr<ExpressionContext> expCtx,
BSONObj filter);
/**
* Class which handles rewriting filter MatchExpressions for FLE2. The functionality is encapsulated
* as a class rather than just a namespace so that the collection readers don't have to be passed
* around as extra arguments to every function.
*
* Exposed in the header file for unit testing purposes. External callers should use the
* rewriteEncryptedFilter() helper function defined below.
*/
class MatchExpressionRewrite {
public:
/**
* Takes in references to collection readers for the ESC and ECC that are used during tag
* computation, along with a BSONObj holding a MatchExpression to rewrite. The rewritten
* BSON is then retrieved by calling get() on the rewriter object.
*/
MatchExpressionRewrite(boost::intrusive_ptr<ExpressionContext> expCtx,
const FLEStateCollectionReader& escReader,
const FLEStateCollectionReader& eccReader,
BSONObj filter)
: _escReader(&escReader), _eccReader(&eccReader) {
// This isn't the "real" query so we don't want to increment Expression
// counters here.
expCtx->stopExpressionCounters();
auto expr = uassertStatusOK(MatchExpressionParser::parse(filter, expCtx));
_result = _rewriteMatchExpression(std::move(expr))->serialize();
}
/**
* Get the rewritten MatchExpression from the object.
*/
BSONObj get() {
return _result.getOwned();
}
/**
* Determine whether a given BSONElement is in fact a FLE find payload.
* Sub-type 6, sub-sub-type 0x05.
*/
virtual bool isFleFindPayload(const BSONElement& elt) {
if (!elt.isBinData(BinDataType::Encrypt)) {
return false;
}
int dataLen;
auto data = elt.binData(dataLen);
return dataLen >= 1 &&
data[0] == static_cast<uint8_t>(EncryptedBinDataType::kFLE2FindEqualityPayload);
}
protected:
/**
* Rewrites a match expression with FLE find payloads into a disjunction on the __safeContent__
* array of tags.
*
* Will rewrite top-level $eq and $in expressions, as well as recursing through $and, $or, $not
* and $nor. All other MatchExpressions, notably $elemMatch, are ignored. This function is only
* used directly during unit testing.
*/
std::unique_ptr<MatchExpression> _rewriteMatchExpression(std::unique_ptr<MatchExpression> expr);
// The default constructor should only be used for mocks in testing.
MatchExpressionRewrite() : _escReader(nullptr), _eccReader(nullptr) {}
private:
/**
* A single rewrite step, called recursively on child expressions.
*/
std::unique_ptr<MatchExpression> _rewrite(MatchExpression* me);
virtual BSONObj rewritePayloadAsTags(BSONElement fleFindPayload);
std::unique_ptr<InMatchExpression> rewriteEq(const EqualityMatchExpression* expr);
std::unique_ptr<InMatchExpression> rewriteIn(const InMatchExpression* expr);
// Holds a pointer so that these can be null for tests, even though the public constructor
// takes a const reference.
const FLEStateCollectionReader* _escReader;
const FLEStateCollectionReader* _eccReader;
BSONObj _result;
};
} // namespace fle
} // namespace mongo
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