refactor into more classes; add more test cases; add LITERAL sanitizer

java/ql/lib/semmle/code/java/frameworks/Regex.qll

@@ -2,6 +2,11 @@
 
 private import semmle.code.java.dataflow.ExternalFlow
 
+/** The class `java.util.regex.Pattern`. */
+class TypeRegexPattern extends Class {
+  TypeRegexPattern() { this.hasQualifiedName("java.util.regex", "Pattern") }
+}
+
 private class RegexModel extends SummaryModelCsv {
   override predicate row(string s) {
     s =

java/ql/lib/semmle/code/java/frameworks/apache/Lang.qll

@@ -46,3 +46,8 @@ class TypeApacheSystemUtils extends Class {
     this.hasQualifiedName(["org.apache.commons.lang", "org.apache.commons.lang3"], "SystemUtils")
   }
 }
+
+/** The class `org.apache.commons.lang3.RegExUtils`. */
+class TypeApacheRegExUtils extends Class {
+  TypeApacheRegExUtils() { this.hasQualifiedName("org.apache.commons.lang3", "RegExUtils") }
+}

java/ql/lib/semmle/code/java/security/RegexInjection.qll

@@ -1,60 +1,37 @@
 /** Provides classes and predicates related to regex injection in Java. */
 
 import java
-import semmle.code.java.dataflow.FlowSources
-import semmle.code.java.dataflow.TaintTracking
-import semmle.code.java.regex.RegexFlowConfigs
+private import semmle.code.java.dataflow.DataFlow
+private import semmle.code.java.frameworks.Regex
+private import semmle.code.java.frameworks.apache.Lang
 
-/**
- * A data flow sink for untrusted user input used to construct regular expressions.
- */
+/** A data flow sink for untrusted user input used to construct regular expressions. */
 abstract class Sink extends DataFlow::ExprNode { }
 
-/**
- * A sanitizer for untrusted user input used to construct regular expressions.
- */
+/** A sanitizer for untrusted user input used to construct regular expressions. */
 abstract class Sanitizer extends DataFlow::ExprNode { }
 
-// TODO: look into further: Pattern.matcher, .pattern() and .toString() as taint steps, .split and .splitAsStream
-/**
- * A data flow sink for untrusted user input used to construct regular expressions.
- */
-private class RegexSink extends Sink {
-  RegexSink() {
+private class RegexInjectionSink extends Sink {
+  RegexInjectionSink() {
     exists(MethodAccess ma, Method m | m = ma.getMethod() |
       ma.getArgument(0) = this.asExpr() and
       (
-        m.getDeclaringType() instanceof TypeString and
-        m.hasName(["matches", "split", "replaceFirst", "replaceAll"])
-        or
-        m.getDeclaringType() instanceof RegexPattern and
-        m.hasName(["compile", "matches"])
+        m instanceof StringRegexMethod or
+        m instanceof PatternRegexMethod
       )
       or
-      m.getDeclaringType() instanceof ApacheRegExUtils and
-      (
-        ma.getArgument(1) = this.asExpr() and
-        // only handles String param here because the other param option, Pattern, is already handled by `java.util.regex.Pattern` above
-        m.getParameterType(1) instanceof TypeString and
-        m.hasName([
-            "removeAll", "removeFirst", "removePattern", "replaceAll", "replaceFirst",
-            "replacePattern"
-          ])
-      )
+      ma.getArgument(1) = this.asExpr() and
+      m instanceof ApacheRegExUtilsMethod
     )
   }
 }
 
-/**
- * A call to a function whose name suggests that it escapes regular
- * expression meta-characters.
- */
-class RegexInjectionSanitizer extends Sanitizer {
+/** A call to a function which escapes regular expression meta-characters. */
+private class RegexInjectionSanitizer extends Sanitizer {
   RegexInjectionSanitizer() {
+    // a function whose name suggests that it escapes regular expression meta-characters
     exists(string calleeName, string sanitize, string regexp |
       calleeName = this.asExpr().(Call).getCallee().getName() and
-      // TODO: add test case for sanitize? I think current tests only check escape
-      // TODO: should this be broader and only look for "escape|saniti[sz]e" and not "regexp?" as well? -- e.g. err on side of FNs?
       sanitize = "(?:escape|saniti[sz]e)" and
       regexp = "regexp?"
     |
@@ -63,31 +40,70 @@ class RegexInjectionSanitizer extends Sanitizer {
               ".*)")
     )
     or
-    // adds Pattern.quote() as a sanitizer
-    // https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html#quote-java.lang.String-: "Metacharacters or escape sequences in the input sequence will be given no special meaning."
-    // see https://rules.sonarsource.com/java/RSPEC-2631 and https://sensei.securecodewarrior.com/recipes/scw:java:regex-injection
+    // a call to the `Pattern.quote` method, which gives metacharacters or escape sequences no special meaning
     exists(MethodAccess ma, Method m | m = ma.getMethod() |
-      m.getDeclaringType() instanceof RegexPattern and
-      (
-        ma.getArgument(0) = this.asExpr() and
-        m.hasName("quote")
-      )
+      ma.getArgument(0) = this.asExpr() and
+      m instanceof PatternQuoteMethod
+    )
+    or
+    // use of Pattern.LITERAL flag with `Pattern.compile` which gives metacharacters or escape sequences no special meaning
+    exists(MethodAccess ma, Method m, Field field | m = ma.getMethod() |
+      ma.getArgument(0) = this.asExpr() and
+      m instanceof PatternRegexMethod and
+      m.hasName("compile") and
+      //ma.getArgument(1).toString() = "Pattern.LITERAL" and
+      field instanceof PatternLiteral and
+      ma.getArgument(1) = field.getAnAccess()
     )
   }
 }
 
-// ******** HELPER CLASSES/METHODS (MAYBE MOVE ELSEWHERE?) ********
-// TODO: move below to Regex.qll??
-/** The Java class `java.util.regex.Pattern`. */
-private class RegexPattern extends RefType {
-  RegexPattern() { this.hasQualifiedName("java.util.regex", "Pattern") }
+/**
+ * The methods of the class `java.lang.String` that take a regular expression
+ * as a parameter.
+ */
+private class StringRegexMethod extends Method {
+  StringRegexMethod() {
+    this.getDeclaringType() instanceof TypeString and
+    this.hasName(["matches", "split", "replaceFirst", "replaceAll"])
+  }
 }
 
-// /** The Java class `java.util.regex.Matcher`. */
-// private class RegexMatcher extends RefType {
-//   RegexMatcher() { this.hasQualifiedName("java.util.regex", "Matcher") }
-// }
-/** The Java class `org.apache.commons.lang3.RegExUtils`. */
-private class ApacheRegExUtils extends RefType {
-  ApacheRegExUtils() { this.hasQualifiedName("org.apache.commons.lang3", "RegExUtils") }
+/**
+ * The methods of the class `java.util.regex.Pattern` that take a regular
+ * expression as a parameter.
+ */
+private class PatternRegexMethod extends Method {
+  PatternRegexMethod() {
+    this.getDeclaringType() instanceof TypeRegexPattern and
+    this.hasName(["compile", "matches"])
+  }
+}
+
+/** The `quote` method of the `java.util.regex.Pattern` class. */
+private class PatternQuoteMethod extends Method {
+  PatternQuoteMethod() { this.hasName(["quote"]) }
+}
+
+/** The `LITERAL` field of the `java.util.regex.Pattern` class. */
+private class PatternLiteral extends Field {
+  PatternLiteral() {
+    this.getDeclaringType() instanceof TypeRegexPattern and
+    this.hasName("LITERAL")
+  }
+}
+
+/**
+ * The methods of the class `org.apache.commons.lang3.RegExUtils` that take
+ * a regular expression of type `String` as a parameter.
+ */
+private class ApacheRegExUtilsMethod extends Method {
+  ApacheRegExUtilsMethod() {
+    this.getDeclaringType() instanceof TypeApacheRegExUtils and
+    // only handles String param here because the other param option, Pattern, is already handled by `java.util.regex.Pattern`
+    this.getParameterType(1) instanceof TypeString and
+    this.hasName([
+        "removeAll", "removeFirst", "removePattern", "replaceAll", "replaceFirst", "replacePattern"
+      ])
+  }
 }

java/ql/lib/semmle/code/java/security/RegexInjectionQuery.qll

@@ -5,9 +5,7 @@ import semmle.code.java.dataflow.FlowSources
 import semmle.code.java.dataflow.TaintTracking
 import semmle.code.java.security.RegexInjection
 
-/**
- * A taint-tracking configuration for untrusted user input used to construct regular expressions.
- */
+/** A taint-tracking configuration for untrusted user input used to construct regular expressions. */
 class RegexInjectionConfiguration extends TaintTracking::Configuration {
   RegexInjectionConfiguration() { this = "RegexInjection" }
 

java/ql/test/query-tests/security/CWE-730/RegexInjectionTest.java

@@ -84,20 +84,55 @@ public class RegexInjectionTest extends HttpServlet {
     String pattern = request.getParameter("pattern");
     String input = request.getParameter("input");
 
-    // TODO: add a "Safe" test for situation when this return value is stored in a variable, then the variable is used in the regex
     escapeSpecialRegexChars(pattern);
 
     // BAD: the pattern is not really sanitized
     return input.matches("^" + pattern + "=.*$"); // $ hasRegexInjection
   }
 
+  public boolean pattern7(javax.servlet.http.HttpServletRequest request) {
+    String pattern = request.getParameter("pattern");
+    String input = request.getParameter("input");
+
+    String escapedPattern = escapeSpecialRegexChars(pattern);
+
+    // Safe: User input is sanitized before constructing the regex
+    return input.matches("^" + escapedPattern + "=.*$");
+  }
+
+  public boolean pattern8(javax.servlet.http.HttpServletRequest request) {
+    String pattern = request.getParameter("pattern");
+    String input = request.getParameter("input");
+
+    // Safe: User input is sanitized before constructing the regex
+    return input.matches("^" + sanitizeSpecialRegexChars(pattern) + "=.*$");
+  }
+
+  public boolean pattern9(javax.servlet.http.HttpServletRequest request) {
+    String pattern = request.getParameter("pattern");
+    String input = request.getParameter("input");
+
+    // Safe: User input is sanitized before constructing the regex
+    return input.matches("^" + sanitiseSpecialRegexChars(pattern) + "=.*$");
+  }
+
   Pattern SPECIAL_REGEX_CHARS = Pattern.compile("[{}()\\[\\]><-=!.+*?^$\\\\|]");
 
-  // TODO: check if any other inbuilt escape/sanitizers in Java APIs
+  // test `escape...regex`
   String escapeSpecialRegexChars(String str) {
     return SPECIAL_REGEX_CHARS.matcher(str).replaceAll("\\\\$0");
   }
 
+  // test `sanitize...regex`
+  String sanitizeSpecialRegexChars(String str) {
+    return SPECIAL_REGEX_CHARS.matcher(str).replaceAll("\\\\$0");
+  }
+
+  // test `sanitise...regex`
+  String sanitiseSpecialRegexChars(String str) {
+    return SPECIAL_REGEX_CHARS.matcher(str).replaceAll("\\\\$0");
+  }
+
   public boolean apache1(javax.servlet.http.HttpServletRequest request) {
     String pattern = request.getParameter("pattern");
     String input = request.getParameter("input");
@@ -148,12 +183,20 @@ public class RegexInjectionTest extends HttpServlet {
     return RegExUtils.replacePattern(input, pattern, "").length() > 0;  // $ hasRegexInjection
   }
 
-  // from https://rules.sonarsource.com/java/RSPEC-2631 to test for Pattern.quote as safe
-  public boolean validate(javax.servlet.http.HttpServletRequest request) {
+  // test `Pattern.quote` as safe
+  public boolean quoteTest(javax.servlet.http.HttpServletRequest request) {
     String regex = request.getParameter("regex");
     String input = request.getParameter("input");
 
-    return input.matches(Pattern.quote(regex));  // Safe: with Pattern.quote, metacharacters or escape sequences will be given no special meaning
+    return input.matches(Pattern.quote(regex));  // Safe
+  }
+
+  // test `Pattern.LITERAL` as safe
+  public boolean literalTest(javax.servlet.http.HttpServletRequest request) {
+    String pattern = request.getParameter("pattern");
+    String input = request.getParameter("input");
+
+    return Pattern.compile(pattern, Pattern.LITERAL).matcher(input).matches();  // Safe
   }
 }