python: Allow optional result=OK

Also add a further test case

python/ql/test/experimental/dataflow/TestUtil/DataflowQueryTest.qll

@@ -9,13 +9,27 @@ class DataFlowQueryTest extends InlineExpectationsTest {
   override string getARelevantTag() { result = "result" }
 
   override predicate hasActualResult(Location location, string element, string tag, string value) {
-    exists(DataFlow::Configuration cfg, DataFlow::Node fromNode, DataFlow::Node toNode |
-      cfg.hasFlow(fromNode, toNode)
-    |
-      location = toNode.getLocation() and
+    exists(DataFlow::Configuration cfg, DataFlow::Node sink | cfg.hasFlowTo(sink) |
+      location = sink.getLocation() and
       tag = "result" and
       value = "BAD" and
-      element = toNode.toString()
+      element = sink.toString()
+    )
+  }
+
+  // We allow annotating any sink with `result=OK` to signal
+  // safe sinks.
+  // Sometimes a line contains both an alert and a safe sink.
+  // In this situation, the annotation form `OK(safe sink)`
+  // can be useful.
+  override predicate hasOptionalResult(Location location, string element, string tag, string value) {
+    exists(DataFlow::Configuration cfg, DataFlow::Node sink |
+      cfg.isSink(sink) or cfg.isSink(sink, _)
+    |
+      location = sink.getLocation() and
+      tag = "result" and
+      value in ["OK", "OK(" + prettyNode(sink) + ")"] and
+      element = sink.toString()
     )
   }
 }
@@ -23,10 +37,11 @@ class DataFlowQueryTest extends InlineExpectationsTest {
 query predicate missingAnnotationOnSink(Location location, string error, string element) {
   error = "ERROR, you should add `# $ MISSING: result=BAD` or `result=OK` annotation" and
   exists(DataFlow::Node sink |
+    exists(sink.getLocation().getFile().getRelativePath()) and
     exists(DataFlow::Configuration cfg | cfg.isSink(sink) or cfg.isSink(sink, _)) and
     location = sink.getLocation() and
     element = prettyExpr(sink.asExpr()) and
-    not any(DataFlow::Configuration config).hasFlow(_, sink) and
+    not exists(DataFlow::Configuration cfg | cfg.hasFlowTo(sink)) and
     not exists(FalseNegativeExpectation missingResult |
       missingResult.getTag() = "result" and
       missingResult.getValue() = "BAD" and
@@ -35,7 +50,7 @@ query predicate missingAnnotationOnSink(Location location, string error, string
     ) and
     not exists(GoodExpectation okResult |
       okResult.getTag() = "result" and
-      okResult.getValue() = "OK" and
+      okResult.getValue() in ["OK", "OK(" + prettyNode(sink) + ")"] and
       okResult.getLocation().getFile() = location.getFile() and
       okResult.getLocation().getStartLine() = location.getStartLine()
     )

python/ql/test/query-tests/Security/CWE-022-PathInjection/DataflowQueryTest.expected

@@ -0,0 +1,2 @@
+missingAnnotationOnSink
+failures

python/ql/test/query-tests/Security/CWE-022-PathInjection/DataflowQueryTest.ql

@@ -0,0 +1,3 @@
+import python
+import experimental.dataflow.TestUtil.DataflowQueryTest
+import semmle.python.security.dataflow.PathInjectionQuery

python/ql/test/query-tests/Security/CWE-022-PathInjection/flask_path_injection.py

@@ -10,7 +10,7 @@ STATIC_DIR = "/server/static/"
 def download_file():
     filename = request.args.get('filename', '')
     # ok since `send_from_directory` ensure this stays within `STATIC_DIR`
-    return send_from_directory(STATIC_DIR, filename) # OK
+    return send_from_directory(STATIC_DIR, filename) # $result=OK
 
 
 # see https://flask.palletsprojects.com/en/1.1.x/api/#flask.send_from_directory
@@ -18,4 +18,4 @@ def download_file():
 def download_file():
     dirname = request.args.get('dirname', '')
     filename = request.args.get('filename', '')
-    return send_from_directory(dirname, filename) # NOT OK
+    return send_from_directory(dirname, filename) # $result=BAD result=OK(filename)

python/ql/test/query-tests/Security/CWE-022-PathInjection/path_injection.py

@@ -10,7 +10,7 @@ STATIC_DIR = "/server/static/"
 @app.route("/path1")
 def path_injection():
     filename = request.args.get('filename', '')
-    f = open(os.path.join(STATIC_DIR, filename)) # NOT OK
+    f = open(os.path.join(STATIC_DIR, filename)) # $result=BAD
 
 
 @app.route("/path2")
@@ -18,7 +18,7 @@ def path_injection():
     # Normalized, but not checked
     filename = request.args.get('filename', '')
     npath = os.path.normpath(os.path.join(STATIC_DIR, filename))
-    f = open(npath)  # NOT OK
+    f = open(npath)  # $result=BAD
 
 
 @app.route("/path3")
@@ -28,7 +28,7 @@ def unsafe_path_normpath():
     npath = os.path.normpath(os.path.join(STATIC_DIR, filename))
     if npath.startswith(STATIC_DIR):
         pass
-    f = open(npath)  # NOT OK
+    f = open(npath)  # $result=BAD
 
 
 @app.route("/path4")
@@ -37,7 +37,7 @@ def safe_path_normpath():
     filename = request.args.get('filename', '')
     npath = os.path.normpath(os.path.join(STATIC_DIR, filename))
     if npath.startswith(STATIC_DIR):
-        f = open(npath)  # OK
+        f = open(npath)  # $result=OK
 
 
 @app.route("/path5")
@@ -45,7 +45,7 @@ def unsafe_path_realpath():
     # Normalized (by `realpath` that also follows symlinks), but not checked properly
     filename = request.args.get('filename', '')
     npath = os.path.realpath(os.path.join(STATIC_DIR, filename))
-    f = open(npath)  # NOT OK
+    f = open(npath)  # $result=BAD
 
 
 @app.route("/path6")
@@ -54,7 +54,7 @@ def safe_path_realpath():
     filename = request.args.get('filename', '')
     npath = os.path.realpath(os.path.join(STATIC_DIR, filename))
     if npath.startswith(STATIC_DIR):
-        f = open(npath)  # OK
+        f = open(npath)  # $result=OK
 
 
 @app.route("/path6")
@@ -62,7 +62,7 @@ def unsafe_path_abspath():
     # Normalized (by `abspath`), but not checked properly
     filename = request.args.get('filename', '')
     npath = os.path.abspath(os.path.join(STATIC_DIR, filename))
-    f = open(npath)  # NOT OK
+    f = open(npath)  # $result=BAD
 
 
 @app.route("/path7")
@@ -71,7 +71,7 @@ def safe_path_abspath():
     filename = request.args.get('filename', '')
     npath = os.path.abspath(os.path.join(STATIC_DIR, filename))
     if npath.startswith(STATIC_DIR):
-        f = open(npath)  # OK
+        f = open(npath)  # $result=OK
 
 
 @app.route("/abspath_tricky")
@@ -84,14 +84,14 @@ def safe_path_abspath_tricky():
     filename = request.args.get('filename', '')
     possibly_unsafe_path = os.path.join(STATIC_DIR, filename)
     if os.path.abspath(possibly_unsafe_path).startswith(STATIC_DIR):
-        f = open(possibly_unsafe_path)  # OK
+        f = open(possibly_unsafe_path)  # $SPURIOUS: result=BAD
 
 
 @app.route("/int-only/<int:foo_id>")
 def flask_int_only(foo_id):
     # This is OK, since the flask routing ensures that `foo_id` MUST be an integer.
     path = os.path.join(STATIC_DIR, foo_id)
-    f = open(path)  # OK TODO: FP
+    f = open(path)  # $spurious: result=BAD
 
 
 @app.route("/not-path/<foo>")
@@ -99,7 +99,7 @@ def flask_not_path(foo):
     # On UNIX systems, this is OK, since without being marked as `<path:foo>`, flask
     # routing ensures that `foo` cannot contain forward slashes (not by using %2F either).
     path = os.path.join(STATIC_DIR, foo)
-    f = open(path)  # OK if only running on UNIX systems, NOT OK if could be running on windows
+    f = open(path)  # $result=BAD // OK if only running on UNIX systems, NOT OK if could be running on windows
 
 
 @app.route("/no-dot-dot")
@@ -110,7 +110,7 @@ def no_dot_dot():
     # handle if `filename` is an absolute path
     if '../' in path:
         return "not this time"
-    f = open(path)  # NOT OK
+    f = open(path)  # $result=BAD
 
 
 @app.route("/no-dot-dot-with-prefix")
@@ -121,7 +121,7 @@ def no_dot_dot_with_prefix():
     # Therefore, for UNIX-only programs, the `../` check is enough to stop path injections.
     if '../' in path:
         return "not this time"
-    f = open(path)  # OK if only running on UNIX systems, NOT OK if could be running on windows
+    f = open(path)  # $result=BAD // OK if only running on UNIX systems, NOT OK if could be running on windows
 
 
 @app.route("/replace-slash")
@@ -129,7 +129,7 @@ def replace_slash():
     filename = request.args.get('filename', '')
     path = os.path.join(STATIC_DIR, filename)
     sanitized = path.replace("/", "_")
-    f = open(sanitized)  # OK if only running on UNIX systems, NOT OK if could be running on windows
+    f = open(sanitized)  # $result=BAD // OK if only running on UNIX systems, NOT OK if could be running on windows
 
 
 @app.route("/stackoverflow-solution")
@@ -139,7 +139,7 @@ def stackoverflow_solution():
     path = os.path.join(STATIC_DIR, filename)
     if os.path.commonprefix((os.path.realpath(path), STATIC_DIR)) != STATIC_DIR:
         return "not this time"
-    f = open(path) # OK TODO: FP
+    f = open(path) # $SPURIOUS: result=BAD
 
 
 SAFE_FILES = ['foo', 'bar', 'baz']
@@ -149,4 +149,4 @@ def safe_set_of_files():
     filename = request.args.get('filename', '')
     if filename in SAFE_FILES:
         path = os.path.join(STATIC_DIR, filename)
-        f = open(path) # OK TODO: FP
+        f = open(path) # $SPURIOUS: result=BAD

python/ql/test/query-tests/Security/CWE-022-PathInjection/test.py

@@ -16,21 +16,21 @@ def normalize(x):
 @app.route("/path")
 def simple():
     x = source()
-    open(x)  # NOT OK
+    open(x)  # $result=BAD
 
 
 @app.route("/path")
 def normalization():
     x = source()
     y = normalize(x)
-    open(y)  # NOT OK
+    open(y)  # $result=BAD
 
 
 @app.route("/path")
 def check():
     x = source()
     if x.startswith("subfolder/"):
-        open(x)  # NOT OK
+        open(x)  # $result=BAD
 
 
 @app.route("/path")
@@ -38,7 +38,7 @@ def normalize_then_check():
     x = source()
     y = normalize(x)
     if y.startswith("subfolder/"):
-        open(y)  # OK
+        open(y)  # $result=OK
 
 
 @app.route("/path")
@@ -46,4 +46,4 @@ def check_then_normalize():
     x = source()
     if x.startswith("subfolder/"):
         y = normalize(x)
-        open(y)  # NOT OK
+        open(y)  # $result=BAD

python/ql/test/query-tests/Security/CWE-022-PathInjection/test_chaining.py

@@ -20,7 +20,7 @@ def normalize_then_check():
     x = source()
     y = normalize(x)  # <--- this call...
     if y.startswith("subfolder/"):
-        open(y)  # OK
+        open(y)  # $result=OK
 
 
 @app.route("/path")
@@ -29,7 +29,7 @@ def normalize_check_normalize():
     y = normalize(x)  # (...or this call...)
     if y.startswith("subfolder/"):
         z = normalize(y)  # <--- ...can jump to here, resulting in FP
-        open(z)  # OK
+        open(z)  # $result=OK
 
 
 # The problem does not manifest if we simply define an alias
@@ -42,4 +42,4 @@ def normalize_check_normalize_alias():
     y = normpath(x)
     if y.startswith("subfolder/"):
         z = normpath(y)
-        open(z)  # OK
+        open(z)  # $result=OK