利用 JSqlParser 防止 SQL 注入

高手文章《jsqlparser:实现基于SQL语法分析的SQL注入攻击检查》介绍了利用 JSqlParser 防止 SQL 注入，写得很好，只不过有两个问题，代码比较复杂，我于是作了简化，只有两个类；其次检测比较严格，连子查询都禁止，我把它开放了。

最简单的 SQL 注入检测

其实，利用 JSqlParser 解析一个语句，是否成功，就能说明这个 SQL 语句有没有被注入了。

try {CCJSqlParserUtil.parse(sql).accept(injectionChecker);return true;
} catch (Exception e) {e.printStackTrace();return false;
}

如果有异常说明被注入了。这是测试例子。

SqlInjectionAnalyzer.check("SELECT * FROM mytable WHERE id = ;DROP TABLE mytable;");

高阶的 JSqlParser 检测

就是文章所介绍的方法，主要是判断表达是否为常量来分析是否注入。主要两个类ConstAnalyzer和SqlInjectionAnalyzer。

package com.ajaxjs.data.util;import net.sf.jsqlparser.expression.BinaryExpression;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.expression.Function;
import net.sf.jsqlparser.expression.operators.conditional.AndExpression;
import net.sf.jsqlparser.expression.operators.conditional.OrExpression;
import net.sf.jsqlparser.expression.operators.relational.ComparisonOperator;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.statement.select.*;
import net.sf.jsqlparser.util.TablesNamesFinder;import java.util.regex.Pattern;/*** 基于 SQL 语法对象的 SQL 注入攻击分析实现** @author guyadong*/
public class SqlInjectionAnalyzer extends TablesNamesFinder {/*** 危险函数名*/private static final String DANGEROUS_FUNCTIONS = "(sleep|benchmark|extractvalue|updatexml|ST_LatFromGeoHash|ST_LongFromGeoHash|GTID_SUBSET|GTID_SUBTRACT|floor|ST_Pointfromgeohash"+ "|geometrycollection|multipoint|polygon|multipolygon|linestring|multilinestring)";//    private static final ThreadLocal<Boolean> disableSubSelect = new ThreadLocal<Boolean>() {
//        @Override
//        protected Boolean initialValue() {
//            return true;
//        }
//    };private final ConstAnalyzer constAnalyzer = new ConstAnalyzer();public SqlInjectionAnalyzer() {super();init(true);}@Overridepublic void visitBinaryExpression(BinaryExpression binaryExpression) {if (binaryExpression instanceof ComparisonOperator) {if (isConst(binaryExpression.getLeftExpression()) && isConst(binaryExpression.getRightExpression()))/* 禁用恒等式 */throw new SecurityException("DISABLE IDENTICAL EQUATION " + binaryExpression);}super.visitBinaryExpression(binaryExpression);}@Overridepublic void visit(AndExpression andExpression) {super.visit(andExpression);checkConstExpress(andExpression.getLeftExpression());checkConstExpress(andExpression.getRightExpression());}@Overridepublic void visit(OrExpression orExpression) {super.visit(orExpression);checkConstExpress(orExpression.getLeftExpression());checkConstExpress(orExpression.getRightExpression());}@Overridepublic void visit(Function function) {if (function.getName().matches(DANGEROUS_FUNCTIONS))/* 禁用危险函数 */throw new SecurityException("DANGEROUS FUNCTION: " + function.getName());super.visit(function);}@Overridepublic void visit(WithItem withItem) {
//        try {
//            /* 允许 WITH 语句中的子查询 */
//            disableSubSelect.set(false);
//            super.visit(withItem);
//        } finally {
//            disableSubSelect.set(true);
//        }}@Overridepublic void visit(SubSelect subSelect) {
//        if (disableSubSelect.get()) // 禁用子查询
//            throw new SecurityException("DISABLE subSelect " + subSelect);}@Overridepublic void visit(Column tableColumn) {if (isBoolean(tableColumn))throw new SecurityException("DISABLE CONST BOOL " + tableColumn);super.visit(tableColumn);}@Overridepublic void visit(PlainSelect plainSelect) {if (plainSelect.getSelectItems() != null) {for (SelectItem item : plainSelect.getSelectItems())item.accept(this);}if (plainSelect.getFromItem() != null)plainSelect.getFromItem().accept(this);if (plainSelect.getJoins() != null) {for (Join join : plainSelect.getJoins()) {join.getRightItem().accept(this);for (Expression e : join.getOnExpressions())e.accept(this);}}if (plainSelect.getWhere() != null) {plainSelect.getWhere().accept(this);checkConstExpress(plainSelect.getWhere());}if (plainSelect.getHaving() != null)plainSelect.getHaving().accept(this);if (plainSelect.getOracleHierarchical() != null)plainSelect.getOracleHierarchical().accept(this);if (plainSelect.getOrderByElements() != null) {for (OrderByElement orderByElement : plainSelect.getOrderByElements())orderByElement.getExpression().accept(this);}if (plainSelect.getGroupBy() != null) {for (Expression expression : plainSelect.getGroupBy().getGroupByExpressionList().getExpressions())expression.accept(this);}}private boolean isConst(Expression expression) {return constAnalyzer.isConstExpression(expression);}private void checkConstExpress(Expression expression) {if (constAnalyzer.isConstExpression(expression))/* 禁用常量表达式 */throw new SecurityException("DISABLE CONST EXPRESSION " + expression);}private static final Pattern BOL = Pattern.compile("(true|false)", Pattern.CASE_INSENSITIVE);/*** 如果{@link Column}没有定义table,且字段名为true/false(不区分大小写)则视为布尔常量*/public static boolean isBoolean(Column column) {return null != column && null == column.getTable() && BOL.matcher(column.getColumnName()).matches();}private static final SqlInjectionAnalyzer injectionChecker = new SqlInjectionAnalyzer();/*** SQL 注入攻击分析器* 对解析后的SQL对象执行注入攻击分析，有注入攻击的危险则抛出异常，* 并通过{@code visitor}参数提供基于AST(抽象语法树)的遍历所有节点的能力。** @param sql SQL语句* @throws SecurityException 输入的SQL语句有语法错误*/public static boolean check(String sql) {boolean allowComplexParsing = CCJSqlParserUtil.getNestingDepth(sql) <= CCJSqlParserUtil.ALLOWED_NESTING_DEPTH;try {CCJSqlParserUtil.newParser(sql).withAllowComplexParsing(allowComplexParsing).Statement().accept(injectionChecker);return true;} catch (Exception e) {e.printStackTrace();return false;}}
}

package com.ajaxjs.data.util;import net.sf.jsqlparser.expression.BinaryExpression;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.expression.Function;
import net.sf.jsqlparser.expression.operators.conditional.AndExpression;
import net.sf.jsqlparser.expression.operators.conditional.OrExpression;
import net.sf.jsqlparser.expression.operators.relational.ComparisonOperator;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.statement.select.*;
import net.sf.jsqlparser.util.TablesNamesFinder;import java.util.regex.Pattern;/*** 基于 SQL 语法对象的 SQL 注入攻击分析实现** @author guyadong*/
public class SqlInjectionAnalyzer extends TablesNamesFinder {/*** 危险函数名*/private static final String DANGEROUS_FUNCTIONS = "(sleep|benchmark|extractvalue|updatexml|ST_LatFromGeoHash|ST_LongFromGeoHash|GTID_SUBSET|GTID_SUBTRACT|floor|ST_Pointfromgeohash"+ "|geometrycollection|multipoint|polygon|multipolygon|linestring|multilinestring)";//    private static final ThreadLocal<Boolean> disableSubSelect = new ThreadLocal<Boolean>() {
//        @Override
//        protected Boolean initialValue() {
//            return true;
//        }
//    };private final ConstAnalyzer constAnalyzer = new ConstAnalyzer();public SqlInjectionAnalyzer() {super();init(true);}@Overridepublic void visitBinaryExpression(BinaryExpression binaryExpression) {if (binaryExpression instanceof ComparisonOperator) {if (isConst(binaryExpression.getLeftExpression()) && isConst(binaryExpression.getRightExpression()))/* 禁用恒等式 */throw new SecurityException("DISABLE IDENTICAL EQUATION " + binaryExpression);}super.visitBinaryExpression(binaryExpression);}@Overridepublic void visit(AndExpression andExpression) {super.visit(andExpression);checkConstExpress(andExpression.getLeftExpression());checkConstExpress(andExpression.getRightExpression());}@Overridepublic void visit(OrExpression orExpression) {super.visit(orExpression);checkConstExpress(orExpression.getLeftExpression());checkConstExpress(orExpression.getRightExpression());}@Overridepublic void visit(Function function) {if (function.getName().matches(DANGEROUS_FUNCTIONS))/* 禁用危险函数 */throw new SecurityException("DANGEROUS FUNCTION: " + function.getName());super.visit(function);}@Overridepublic void visit(WithItem withItem) {
//        try {
//            /* 允许 WITH 语句中的子查询 */
//            disableSubSelect.set(false);
//            super.visit(withItem);
//        } finally {
//            disableSubSelect.set(true);
//        }}@Overridepublic void visit(SubSelect subSelect) {
//        if (disableSubSelect.get()) // 禁用子查询
//            throw new SecurityException("DISABLE subSelect " + subSelect);}@Overridepublic void visit(Column tableColumn) {if (isBoolean(tableColumn))throw new SecurityException("DISABLE CONST BOOL " + tableColumn);super.visit(tableColumn);}@Overridepublic void visit(PlainSelect plainSelect) {if (plainSelect.getSelectItems() != null) {for (SelectItem item : plainSelect.getSelectItems())item.accept(this);}if (plainSelect.getFromItem() != null)plainSelect.getFromItem().accept(this);if (plainSelect.getJoins() != null) {for (Join join : plainSelect.getJoins()) {join.getRightItem().accept(this);for (Expression e : join.getOnExpressions())e.accept(this);}}if (plainSelect.getWhere() != null) {plainSelect.getWhere().accept(this);checkConstExpress(plainSelect.getWhere());}if (plainSelect.getHaving() != null)plainSelect.getHaving().accept(this);if (plainSelect.getOracleHierarchical() != null)plainSelect.getOracleHierarchical().accept(this);if (plainSelect.getOrderByElements() != null) {for (OrderByElement orderByElement : plainSelect.getOrderByElements())orderByElement.getExpression().accept(this);}if (plainSelect.getGroupBy() != null) {for (Expression expression : plainSelect.getGroupBy().getGroupByExpressionList().getExpressions())expression.accept(this);}}private boolean isConst(Expression expression) {return constAnalyzer.isConstExpression(expression);}private void checkConstExpress(Expression expression) {if (constAnalyzer.isConstExpression(expression))/* 禁用常量表达式 */throw new SecurityException("DISABLE CONST EXPRESSION " + expression);}private static final Pattern BOL = Pattern.compile("(true|false)", Pattern.CASE_INSENSITIVE);/*** 如果{@link Column}没有定义table,且字段名为true/false(不区分大小写)则视为布尔常量*/public static boolean isBoolean(Column column) {return null != column && null == column.getTable() && BOL.matcher(column.getColumnName()).matches();}private static final SqlInjectionAnalyzer injectionChecker = new SqlInjectionAnalyzer();/*** SQL 注入攻击分析器* 对解析后的SQL对象执行注入攻击分析，有注入攻击的危险则抛出异常，* 并通过{@code visitor}参数提供基于AST(抽象语法树)的遍历所有节点的能力。** @param sql SQL语句* @throws SecurityException 输入的SQL语句有语法错误*/public static boolean check(String sql) {boolean allowComplexParsing = CCJSqlParserUtil.getNestingDepth(sql) <= CCJSqlParserUtil.ALLOWED_NESTING_DEPTH;try {CCJSqlParserUtil.newParser(sql).withAllowComplexParsing(allowComplexParsing).Statement().accept(injectionChecker);return true;} catch (Exception e) {e.printStackTrace();return false;}}
}

测试：

package com.ajaxjs.data;import com.ajaxjs.data.util.SqlInjectionAnalyzer;
import org.junit.Test;import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;public class TestSqlInject {@Testpublic void test() {assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where id in (select id from other)"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where 2=2.0 or 2 != 4"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where 1!=2.0"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where id=floor(2.0)"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where not true"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where 1 or id > 0"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where 'tom' or id > 0"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where '-2.3' "));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where 2 "));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where (3+2) "));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where  -1 IS TRUE"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where 'hello' is null "));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where '2022-10-31' and id > 0"));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where id > 0 or 1!=2.0 "));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device where id > 0 or 1 in (1,3,4) "));assertFalse(SqlInjectionAnalyzer.check("select * from dc_device UNION select name from other"));assertTrue(SqlInjectionAnalyzer.check("WITH SUB1 AS (SELECT user FROM t1) SELECT * FROM T2 WHERE id > 123 "));boolean check = SqlInjectionAnalyzer.check("SELECT * FROM mytable WHERE id = ;DROP TABLE mytable;");System.out.println(check);}}