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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.
*/
#include <memory>
#include "query_rewriter.h"
#include "mongo/bson/bsonelement.h"
#include "mongo/bson/bsonmisc.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/bson/bsontypes.h"
#include "mongo/db/matcher/expression_leaf.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/expression_context_for_test.h"
#include "mongo/db/query/fle/encrypted_predicate.h"
#include "mongo/db/query/fle/encrypted_predicate_test_fixtures.h"
#include "mongo/db/query/fle/query_rewriter_interface.h"
#include "mongo/idl/server_parameter_test_util.h"
#include "mongo/unittest/unittest.h"
#include "mongo/util/overloaded_visitor.h"
namespace mongo {
namespace {
/*
* The server rewrite itself is only responsible for traversing agg and MatchExpressions and
* executing whatever rewrites are registered. For unit testing, we will only verify that this
* traversal and rewrite is happening properly using a mock predicate rewriter that rewrites any
* equality with an object with the key `encrypt` to a $gt operator. Unit tests for the actual
* rewrites while mocking out tag generation are located in the test file for each encrypted
* predicate type. Full end-to-end testing happens in jstests. This organization ensures that we
* don't write redundant tests that each index type is properly rewritten under different
* circumstances, when the same exact code is called for each index type.
*/
class MockPredicateRewriter : public fle::EncryptedPredicate {
public:
MockPredicateRewriter(const fle::QueryRewriterInterface* rewriter)
: EncryptedPredicate(rewriter) {}
protected:
bool isPayload(const BSONElement& elt) const override {
if (!elt.isABSONObj()) {
return false;
}
return elt.Obj().firstElementFieldNameStringData() == "encrypt"_sd;
}
bool isPayload(const Value& v) const override {
if (!v.isObject()) {
return false;
}
return !v.getDocument().getField("encrypt").missing();
}
std::vector<PrfBlock> generateTags(fle::BSONValue payload) const override {
return {};
};
// Encrypted values will be rewritten from $eq to $gt. This is an arbitrary decision just to
// make sure that the rewrite works properly.
std::unique_ptr<MatchExpression> rewriteToTagDisjunction(MatchExpression* expr) const override {
invariant(expr->matchType() == MatchExpression::EQ);
auto eqMatch = static_cast<EqualityMatchExpression*>(expr);
if (!isPayload(eqMatch->getData())) {
return nullptr;
}
return std::make_unique<GTMatchExpression>(eqMatch->path(),
eqMatch->getData().Obj().firstElement());
};
std::unique_ptr<Expression> rewriteToTagDisjunction(Expression* expr) const override {
return nullptr;
}
std::unique_ptr<MatchExpression> rewriteToRuntimeComparison(
MatchExpression* expr) const override {
return nullptr;
}
std::unique_ptr<Expression> rewriteToRuntimeComparison(Expression* expr) const override {
return nullptr;
}
private:
EncryptedBinDataType encryptedBinDataType() const override {
return EncryptedBinDataType::kPlaceholder; // return the 0 type. this isn't used anywhere.
}
};
void setMockRewriteMaps(fle::MatchTypeToRewriteMap& match,
fle::ExpressionToRewriteMap& agg,
fle::TagMap& tags,
std::set<StringData>& encryptedFields) {
match[MatchExpression::EQ] = [&](auto* rewriter, auto* expr) {
return MockPredicateRewriter{rewriter}.rewrite(expr);
};
}
class MockQueryRewriter : public fle::QueryRewriter {
public:
MockQueryRewriter(fle::ExpressionToRewriteMap* exprRewrites,
fle::MatchTypeToRewriteMap* matchRewrites)
: fle::QueryRewriter(new ExpressionContextForTest(), *exprRewrites, *matchRewrites) {
setMockRewriteMaps(*matchRewrites, *exprRewrites, _tags, _encryptedFields);
}
BSONObj rewriteMatchExpressionForTest(const BSONObj& obj) {
auto res = rewriteMatchExpression(obj);
return res ? res.value() : obj;
}
private:
fle::TagMap _tags;
std::set<StringData> _encryptedFields;
};
class FLEServerRewriteTest : public unittest::Test {
public:
FLEServerRewriteTest() : _mock(nullptr) {}
void setUp() override {
_mock = std::make_unique<MockQueryRewriter>(&_agg, &_match);
}
void tearDown() override {}
protected:
std::unique_ptr<MockQueryRewriter> _mock;
fle::ExpressionToRewriteMap _agg;
fle::MatchTypeToRewriteMap _match;
};
#define ASSERT_MATCH_EXPRESSION_REWRITE(input, expected) \
auto actual = _mock->rewriteMatchExpressionForTest(fromjson(input)); \
ASSERT_BSONOBJ_EQ(actual, fromjson(expected));
#define TEST_FLE_REWRITE_MATCH(name, input, expected) \
TEST_F(FLEServerRewriteTest, name##_MatchExpression) { \
ASSERT_MATCH_EXPRESSION_REWRITE(input, expected); \
}
TEST_FLE_REWRITE_MATCH(TopLevel_DottedPath,
"{'user.ssn': {$eq: {encrypt: 2}}}",
"{'user.ssn': {$gt: 2}}");
TEST_FLE_REWRITE_MATCH(TopLevel_Conjunction_BothEncrypted,
"{$and: [{ssn: {encrypt: 2}}, {age: {encrypt: 4}}]}",
"{$and: [{ssn: {$gt: 2}}, {age: {$gt: 4}}]}");
TEST_FLE_REWRITE_MATCH(TopLevel_Conjunction_PartlyEncrypted,
"{$and: [{ssn: {encrypt: 2}}, {age: {plain: 4}}]}",
"{$and: [{ssn: {$gt: 2}}, {age: {$eq: {plain: 4}}}]}");
TEST_FLE_REWRITE_MATCH(TopLevel_Conjunction_PartlyEncryptedWithUnregisteredOperator,
"{$and: [{ssn: {encrypt: 2}}, {age: {$lt: {encrypt: 4}}}]}",
"{$and: [{ssn: {$gt: 2}}, {age: {$lt: {encrypt: 4}}}]}");
TEST_FLE_REWRITE_MATCH(TopLevel_Encrypted_Nested_Unecrypted,
"{$and: [{ssn: {encrypt: 2}}, {user: {region: 'US'}}]}",
"{$and: [{ssn: {$gt: 2}}, {user: {$eq: {region: 'US'}}}]}");
TEST_FLE_REWRITE_MATCH(TopLevel_Not,
"{ssn: {$not: {$eq: {encrypt: 5}}}}",
"{ssn: {$not: {$gt: 5}}}");
TEST_FLE_REWRITE_MATCH(TopLevel_Neq, "{ssn: {$ne: {encrypt: 5}}}", "{ssn: {$not: {$gt: 5}}}}");
TEST_FLE_REWRITE_MATCH(
NestedConjunction,
"{$and: [{$and: [{ssn: {encrypt: 2}}, {other: 'field'}]}, {otherSsn: {encrypt: 3}}]}",
"{$and: [{$and: [{ssn: {$gt: 2}}, {other: {$eq: 'field'}}]}, {otherSsn: {$gt: 3}}]}");
TEST_FLE_REWRITE_MATCH(TopLevel_Nor,
"{$nor: [{ssn: {encrypt: 5}}, {other: {$eq: 'field'}}]}",
"{$nor: [{ssn: {$gt: 5}}, {other: {$eq: 'field'}}]}");
TEST_FLE_REWRITE_MATCH(TopLevel_Or,
"{$or: [{ssn: {encrypt: 5}}, {other: {$eq: 'field'}}]}",
"{$or: [{ssn: {$gt: 5}}, {other: {$eq: 'field'}}]}");
} // namespace
} // namespace mongo
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