[feature] Add 'check grant' to see if (current user has been granted certain access rights elements && the elements exist).

src/Interpreters/Access/InterpreterCheckGrantQuery.cpp

@@ -0,0 +1,114 @@
+#include <Interpreters/InterpreterFactory.h>
+#include <Interpreters/Access/InterpreterCheckGrantQuery.h>
+#include <Interpreters/executeQuery.h>
+#include <Parsers/Access/ASTCheckGrantQuery.h>
+#include <Parsers/Access/ASTRolesOrUsersSet.h>
+#include <Access/AccessControl.h>
+#include <Access/ContextAccess.h>
+#include <Access/Role.h>
+#include <Access/RolesOrUsersSet.h>
+#include <Access/User.h>
+#include <Interpreters/Context.h>
+#include <Interpreters/removeOnClusterClauseIfNeeded.h>
+#include <Interpreters/QueryLog.h>
+#include <Interpreters/executeDDLQueryOnCluster.h>
+#include <boost/range/algorithm/copy.hpp>
+#include <boost/range/algorithm/set_algorithm.hpp>
+#include <boost/range/algorithm_ext/erase.hpp>
+#include <Interpreters/DatabaseCatalog.h>
+#include "Databases/IDatabase.h"
+#include "Storages/IStorage.h"
+
+namespace DB
+{
+
+namespace
+{
+    /// Extracts access rights elements which are going to check grant
+    void collectAccessRightsElementsToGrantOrRevoke(
+        const ASTCheckGrantQuery & query,
+        AccessRightsElements & elements_to_check_grant)
+    {
+        elements_to_check_grant.clear();
+        /// GRANT
+        elements_to_check_grant = query.access_rights_elements;
+    }
+}
+
+
+BlockIO InterpreterCheckGrantQuery::execute()
+{
+    auto & query = query_ptr->as<ASTCheckGrantQuery &>();
+    query.access_rights_elements.eraseNonGrantable();
+
+    auto current_user_access = getContext()->getAccess();
+
+    /// Collect access rights elements which will be checked.
+    AccessRightsElements elements_to_check_grant;
+    collectAccessRightsElementsToGrantOrRevoke(query, elements_to_check_grant);
+
+
+    /// Replacing empty database with the default. This step must be done before replication to avoid privilege escalation.
+    String current_database = getContext()->getCurrentDatabase();
+    elements_to_check_grant.replaceEmptyDatabase(current_database);
+    query.access_rights_elements.replaceEmptyDatabase(current_database);
+    auto *logger = &::Poco::Logger::get("CheckGrantQuery");
+
+    /// Check If Table/Columns exist.
+    for (const auto & elem : elements_to_check_grant)
+    {
+        try
+        {
+            DatabasePtr database;
+            database = DatabaseCatalog::instance().getDatabase(elem.database);
+            if (!database->isTableExist(elem.table, getContext()))
+            {
+                /// Table not found.
+                return executeQuery("SELECT 0 AS CHECK_GRANT", getContext(), QueryFlags{.internal = true}).second;
+            }
+            auto table = database->getTable(elem.table, getContext());
+
+            auto column_name_with_sizes = table->getColumnSizes();
+            for (const auto & elem_col : elem.columns)
+            {
+                bool founded = false;
+                for (const auto & col_in_table : column_name_with_sizes)
+                {
+                    if (col_in_table.first == elem_col)
+                    {
+                        founded = true;
+                        break;
+                    }
+                }
+                if (!founded)
+                {
+                    /// Column not found.
+                    return executeQuery("SELECT 0 AS CHECK_GRANT", getContext(), QueryFlags{.internal = true}).second;
+                }
+            }
+        }
+        catch (...)
+        {
+            tryLogCurrentException(logger);
+            return executeQuery("SELECT 0 AS CHECK_GRANT", getContext(), QueryFlags{.internal = true}).second;
+        }
+    }
+    bool user_is_granted = current_user_access->isGranted(elements_to_check_grant);
+    if (!user_is_granted)
+    {
+        return executeQuery("SELECT 0 AS CHECK_GRANT", getContext(), QueryFlags{.internal = true}).second;
+    }
+
+    return executeQuery("SELECT 1 AS CHECK_GRANT", getContext(), QueryFlags{.internal = true}).second;
+}
+
+void registerInterpreterCheckGrantQuery(InterpreterFactory & factory)
+{
+    auto create_fn = [] (const InterpreterFactory::Arguments & args)
+    {
+        return std::make_unique<InterpreterCheckGrantQuery>(args.query, args.context);
+    };
+    factory.registerInterpreter("InterpreterCheckGrantQuery", create_fn);
+}
+
+}

src/Interpreters/Access/InterpreterCheckGrantQuery.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <Core/UUID.h>
+#include <Interpreters/IInterpreter.h>
+#include <Parsers/IAST_fwd.h>
+
+
+namespace DB
+{
+
+class ASTCheckGrantQuery;
+struct User;
+struct Role;
+
+class InterpreterCheckGrantQuery : public IInterpreter, WithMutableContext
+{
+public:
+    InterpreterCheckGrantQuery(const ASTPtr & query_ptr_, ContextMutablePtr context_) : WithMutableContext(context_), query_ptr(query_ptr_) {}
+
+    BlockIO execute() override;
+
+private:
+    ASTPtr query_ptr;
+};
+
+}

src/Interpreters/InterpreterFactory.cpp

@@ -60,6 +60,7 @@
 #include <Parsers/ASTExternalDDLQuery.h>
 #include <Common/ProfileEvents.h>
 #include <Common/typeid_cast.h>
+#include "Parsers/Access/ASTCheckGrantQuery.h"
 #include <Core/Settings.h>
 
 
@@ -298,6 +299,10 @@ InterpreterFactory::InterpreterPtr InterpreterFactory::get(ASTPtr & query, Conte
     {
         interpreter_name = "InterpreterShowGrantsQuery";
     }
+    else if (query->as<ASTCheckGrantQuery>())
+    {
+        interpreter_name = "InterpreterCheckGrantQuery";
+    }
     else if (query->as<ASTShowAccessEntitiesQuery>())
     {
         interpreter_name = "InterpreterShowAccessEntitiesQuery";

src/Interpreters/registerInterpreters.cpp

@@ -45,6 +45,7 @@ void registerInterpreterDropNamedCollectionQuery(InterpreterFactory & factory);
 void registerInterpreterGrantQuery(InterpreterFactory & factory);
 void registerInterpreterShowCreateAccessEntityQuery(InterpreterFactory & factory);
 void registerInterpreterShowGrantsQuery(InterpreterFactory & factory);
+void registerInterpreterCheckGrantQuery(InterpreterFactory & factory);
 void registerInterpreterShowAccessEntitiesQuery(InterpreterFactory & factory);
 void registerInterpreterShowAccessQuery(InterpreterFactory & factory);
 void registerInterpreterShowPrivilegesQuery(InterpreterFactory & factory);
@@ -104,6 +105,7 @@ void registerInterpreters()
     registerInterpreterGrantQuery(factory);
     registerInterpreterShowCreateAccessEntityQuery(factory);
     registerInterpreterShowGrantsQuery(factory);
+    registerInterpreterCheckGrantQuery(factory);
     registerInterpreterShowAccessEntitiesQuery(factory);
     registerInterpreterShowAccessQuery(factory);
     registerInterpreterShowPrivilegesQuery(factory);

src/Parsers/Access/ASTCheckGrantQuery.cpp

@@ -0,0 +1,30 @@
+#include <Parsers/Access/ASTCheckGrantQuery.h>
+#include <Parsers/Access/ASTRolesOrUsersSet.h>
+#include "Common/logger_useful.h"
+#include <Common/quoteString.h>
+#include <IO/Operators.h>
+
+
+namespace DB
+{
+
+String ASTCheckGrantQuery::getID(char) const
+{
+    return "CheckGrantQuery";
+}
+
+
+ASTPtr ASTCheckGrantQuery::clone() const
+{
+    auto res = std::make_shared<ASTCheckGrantQuery>(*this);
+
+    return res;
+}
+
+
+void ASTCheckGrantQuery::replaceEmptyDatabase(const String & current_database)
+{
+    access_rights_elements.replaceEmptyDatabase(current_database);
+}
+
+}

src/Parsers/Access/ASTCheckGrantQuery.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <Parsers/IAST.h>
+#include <Access/Common/AccessRightsElement.h>
+#include <Parsers/ASTQueryWithOnCluster.h>
+#include "Parsers/ASTQueryParameter.h"
+
+
+namespace DB
+{
+class ASTRolesOrUsersSet;
+
+
+/** Parses queries like
+  * CHECK GRANT access_type[(column_name [,...])] [,...] ON {db.table|db.*|*.*|table|*}
+  */
+class ASTCheckGrantQuery : public IAST
+{
+public:
+    AccessRightsElements access_rights_elements;
+
+    String getID(char) const override;
+    ASTPtr clone() const override;
+    void replaceEmptyDatabase(const String & current_database);
+    QueryKind getQueryKind() const override { return QueryKind::Check; }
+};
+}

src/Parsers/Access/ParserCheckGrantQuery.cpp

@@ -0,0 +1,232 @@
+#include <Parsers/ASTIdentifier_fwd.h>
+#include <Parsers/ASTLiteral.h>
+#include <Parsers/Access/ASTCheckGrantQuery.h>
+#include <Parsers/Access/ASTRolesOrUsersSet.h>
+#include <Parsers/Access/ParserCheckGrantQuery.h>
+#include <Parsers/Access/ParserRolesOrUsersSet.h>
+#include <Parsers/ExpressionElementParsers.h>
+#include <Parsers/ExpressionListParsers.h>
+#include <Parsers/parseDatabaseAndTableName.h>
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/range/algorithm_ext/erase.hpp>
+
+
+namespace DB
+{
+namespace ErrorCodes
+{
+    extern const int INVALID_GRANT;
+    extern const int SYNTAX_ERROR;
+}
+
+namespace
+{
+    bool parseAccessFlags(IParser::Pos & pos, Expected & expected, AccessFlags & access_flags)
+    {
+        static constexpr auto is_one_of_access_type_words = [](IParser::Pos & pos_)
+        {
+            if (pos_->type != TokenType::BareWord)
+                return false;
+            std::string_view word{pos_->begin, pos_->size()};
+            return !(boost::iequals(word, toStringView(Keyword::ON)) || boost::iequals(word, toStringView(Keyword::TO)) || boost::iequals(word, toStringView(Keyword::FROM)));
+        };
+
+        expected.add(pos, "access type");
+
+        return IParserBase::wrapParseImpl(pos, [&]
+        {
+            if (!is_one_of_access_type_words(pos))
+                return false;
+
+            String str;
+            do
+            {
+                if (!str.empty())
+                    str += " ";
+                str += std::string_view(pos->begin, pos->size());
+                ++pos;
+            }
+            while (is_one_of_access_type_words(pos));
+
+            try
+            {
+                access_flags = AccessFlags{str};
+            }
+            catch (...)
+            {
+                return false;
+            }
+
+            return true;
+        });
+    }
+
+
+    bool parseColumnNames(IParser::Pos & pos, Expected & expected, Strings & columns)
+    {
+        return IParserBase::wrapParseImpl(pos, [&]
+        {
+            if (!ParserToken{TokenType::OpeningRoundBracket}.ignore(pos, expected))
+                return false;
+
+            ASTPtr ast;
+            if (!ParserList{std::make_unique<ParserIdentifier>(), std::make_unique<ParserToken>(TokenType::Comma), false}.parse(pos, ast, expected))
+                return false;
+
+            Strings res_columns;
+            for (const auto & child : ast->children)
+                res_columns.emplace_back(getIdentifierName(child));
+
+            if (!ParserToken{TokenType::ClosingRoundBracket}.ignore(pos, expected))
+                return false;
+
+            columns = std::move(res_columns);
+            return true;
+        });
+    }
+
+    bool parseAccessFlagsWithColumns(IParser::Pos & pos, Expected & expected,
+                                     std::vector<std::pair<AccessFlags, Strings>> & access_and_columns)
+    {
+        std::vector<std::pair<AccessFlags, Strings>> res;
+
+        auto parse_access_and_columns = [&]
+        {
+            AccessFlags access_flags;
+            if (!parseAccessFlags(pos, expected, access_flags))
+                return false;
+
+            Strings columns;
+            parseColumnNames(pos, expected, columns);
+            res.emplace_back(access_flags, std::move(columns));
+            return true;
+        };
+
+        if (!ParserList::parseUtil(pos, expected, parse_access_and_columns, false))
+            return false;
+
+        access_and_columns = std::move(res);
+        return true;
+    }
+
+
+    bool parseElementsWithoutOptions(IParser::Pos & pos, Expected & expected, AccessRightsElements & elements)
+    {
+        return IParserBase::wrapParseImpl(pos, [&]
+        {
+            AccessRightsElements res_elements;
+
+            auto parse_around_on = [&]
+            {
+                std::vector<std::pair<AccessFlags, Strings>> access_and_columns;
+                if (!parseAccessFlagsWithColumns(pos, expected, access_and_columns))
+                    return false;
+
+                String database_name, table_name, parameter;
+                bool any_database = false, any_table = false, any_parameter = false;
+
+                size_t is_global_with_parameter = 0;
+                for (const auto & elem : access_and_columns)
+                {
+                    if (elem.first.isGlobalWithParameter())
+                        ++is_global_with_parameter;
+                }
+
+                if (!ParserKeyword{Keyword::ON}.ignore(pos, expected))
+                    return false;
+
+                if (is_global_with_parameter && is_global_with_parameter == access_and_columns.size())
+                {
+                    ASTPtr parameter_ast;
+                    if (ParserToken{TokenType::Asterisk}.ignore(pos, expected))
+                    {
+                        any_parameter = true;
+                    }
+                    else if (ParserIdentifier{}.parse(pos, parameter_ast, expected))
+                    {
+                        any_parameter = false;
+                        parameter = getIdentifierName(parameter_ast);
+                    }
+                    else
+                        return false;
+
+                    any_database = any_table = true;
+                }
+                else if (!parseDatabaseAndTableNameOrAsterisks(pos, expected, database_name, any_database, table_name, any_table))
+                {
+                    return false;
+                }
+
+                for (auto & [access_flags, columns] : access_and_columns)
+                {
+                    AccessRightsElement element;
+                    element.access_flags = access_flags;
+                    element.any_column = columns.empty();
+                    element.columns = std::move(columns);
+                    element.any_database = any_database;
+                    element.database = database_name;
+                    element.any_table = any_table;
+                    element.any_parameter = any_parameter;
+                    element.table = table_name;
+                    element.parameter = parameter;
+                    res_elements.emplace_back(std::move(element));
+                }
+
+                return true;
+            };
+
+            if (!ParserList::parseUtil(pos, expected, parse_around_on, false))
+                return false;
+
+            elements = std::move(res_elements);
+            return true;
+        });
+    }
+
+    void throwIfNotGrantable(AccessRightsElements & elements)
+    {
+        std::erase_if(elements, [](AccessRightsElement & element)
+        {
+            if (element.empty())
+                return true;
+            auto old_flags = element.access_flags;
+            element.eraseNonGrantable();
+            if (!element.empty())
+                return false;
+
+            if (!element.any_column)
+                throw Exception(ErrorCodes::INVALID_GRANT, "{} cannot check grant on the column level", old_flags.toString());
+            else if (!element.any_table)
+                throw Exception(ErrorCodes::INVALID_GRANT, "{} cannot check grant on the table level", old_flags.toString());
+            else if (!element.any_database)
+                throw Exception(ErrorCodes::INVALID_GRANT, "{} cannot check grant on the database level", old_flags.toString());
+            else if (!element.any_parameter)
+                throw Exception(ErrorCodes::INVALID_GRANT, "{} cannot check grant on the global with parameter level", old_flags.toString());
+            else
+                throw Exception(ErrorCodes::INVALID_GRANT, "{} cannot check grant", old_flags.toString());
+        });
+    }
+}
+
+
+bool ParserCheckGrantQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
+{
+    if (!ParserKeyword{Keyword::CHECK_GRANT}.ignore(pos, expected))
+        return false;
+
+
+    AccessRightsElements elements;
+
+    if (!parseElementsWithoutOptions(pos, expected, elements) )
+        return false;
+
+    throwIfNotGrantable(elements);
+
+    auto query = std::make_shared<ASTCheckGrantQuery>();
+    node = query;
+
+    query->access_rights_elements = std::move(elements);
+
+    return true;
+}
+}

src/Parsers/Access/ParserCheckGrantQuery.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <Parsers/IParserBase.h>
+
+
+namespace DB
+{
+/** Parses queries like
+  * CHECK GRANT access_type[(column_name [,...])] [,...] ON {db.table|db.*|*.*|table|*}
+  */
+class ParserCheckGrantQuery : public IParserBase
+{
+protected:
+    const char * getName() const override { return "CHECK GRANT"; }
+    bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
+};
+}

src/Parsers/CommonParsers.h

@@ -78,6 +78,7 @@ namespace DB
     MR_MACROS(CHARACTER, "CHARACTER") \
     MR_MACROS(CHECK_ALL_TABLES, "CHECK ALL TABLES") \
     MR_MACROS(CHECK_TABLE, "CHECK TABLE") \
+    MR_MACROS(CHECK_GRANT, "CHECK GRANT")\
     MR_MACROS(CHECK, "CHECK") \
     MR_MACROS(CLEANUP, "CLEANUP") \
     MR_MACROS(CLEAR_COLUMN, "CLEAR COLUMN") \

src/Parsers/ParserQuery.cpp

@@ -28,6 +28,7 @@
 #include <Parsers/Access/ParserGrantQuery.h>
 #include <Parsers/Access/ParserMoveAccessEntityQuery.h>
 #include <Parsers/Access/ParserSetRoleQuery.h>
+#include "Parsers/Access/ParserCheckGrantQuery.h"
 
 
 namespace DB
@@ -56,6 +57,7 @@ bool ParserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
     ParserDropAccessEntityQuery drop_access_entity_p;
     ParserMoveAccessEntityQuery move_access_entity_p;
     ParserGrantQuery grant_p;
+    ParserCheckGrantQuery check_grant_p;
     ParserSetRoleQuery set_role_p;
     ParserExternalDDLQuery external_ddl_p;
     ParserTransactionControl transaction_control_p;
@@ -82,6 +84,7 @@ bool ParserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
         || drop_access_entity_p.parse(pos, node, expected)
         || move_access_entity_p.parse(pos, node, expected)
         || grant_p.parse(pos, node, expected)
+        || check_grant_p.parse(pos, node, expected)
         || external_ddl_p.parse(pos, node, expected)
         || transaction_control_p.parse(pos, node, expected)
         || delete_p.parse(pos, node, expected);