Python: TarSlip sanitizer: handle not

Author: RasmusWL

python/ql/src/Security/CWE-022/TarSlip.ql

@@ -124,8 +124,16 @@ class TarFileInfoSanitizer extends Sanitizer {
     /** The test `if <path_sanitizing_test>:` clears taint on its `false` edge. */
     override predicate sanitizingEdge(TaintKind taint, PyEdgeRefinement test) {
         taint instanceof TarFileInfo and
-        path_sanitizing_test(test.getTest()) and
-        test.getSense() = false
+        clears_taint_on_false_edge(test.getTest(), test.getSense())
+    }
+
+    private predicate clears_taint_on_false_edge(ControlFlowNode test, boolean sense) {
+        path_sanitizing_test(test) and
+        sense = false
+        or
+        // handle `not` (also nested)
+        test.(UnaryExprNode).getNode().getOp() instanceof Not and
+        clears_taint_on_false_edge(test.(UnaryExprNode).getOperand(), sense.booleanNot())
     }
 }
 

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

@@ -21,16 +21,9 @@ edges
 | tarslip.py:57:1:57:17 | tarfile.entry | tarslip.py:59:21:59:25 | tarfile.entry |
 | tarslip.py:57:14:57:16 | tarfile.open | tarslip.py:57:1:57:17 | tarfile.entry |
 | tarslip.py:57:14:57:16 | tarfile.open | tarslip.py:57:1:57:17 | tarfile.entry |
-| tarslip.py:63:7:63:39 | tarfile.open | tarslip.py:64:14:64:16 | tarfile.open |
-| tarslip.py:63:7:63:39 | tarfile.open | tarslip.py:64:14:64:16 | tarfile.open |
-| tarslip.py:64:1:64:17 | tarfile.entry | tarslip.py:68:21:68:25 | tarfile.entry |
-| tarslip.py:64:1:64:17 | tarfile.entry | tarslip.py:68:21:68:25 | tarfile.entry |
-| tarslip.py:64:14:64:16 | tarfile.open | tarslip.py:64:1:64:17 | tarfile.entry |
-| tarslip.py:64:14:64:16 | tarfile.open | tarslip.py:64:1:64:17 | tarfile.entry |
 #select
 | tarslip.py:13:1:13:3 | tar | tarslip.py:12:7:12:39 | tarfile.open | tarslip.py:13:1:13:3 | tarfile.open | Extraction of tarfile from $@ | tarslip.py:12:7:12:39 | Attribute() | a potentially untrusted source |
 | tarslip.py:18:17:18:21 | entry | tarslip.py:16:7:16:39 | tarfile.open | tarslip.py:18:17:18:21 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:16:7:16:39 | Attribute() | a potentially untrusted source |
 | tarslip.py:37:17:37:21 | entry | tarslip.py:33:7:33:39 | tarfile.open | tarslip.py:37:17:37:21 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:33:7:33:39 | Attribute() | a potentially untrusted source |
 | tarslip.py:41:24:41:26 | tar | tarslip.py:40:7:40:39 | tarfile.open | tarslip.py:41:24:41:26 | tarfile.open | Extraction of tarfile from $@ | tarslip.py:40:7:40:39 | Attribute() | a potentially untrusted source |
 | tarslip.py:59:21:59:25 | entry | tarslip.py:56:7:56:39 | tarfile.open | tarslip.py:59:21:59:25 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:56:7:56:39 | Attribute() | a potentially untrusted source |
-| tarslip.py:68:21:68:25 | entry | tarslip.py:63:7:63:39 | tarfile.open | tarslip.py:68:21:68:25 | tarfile.entry | Extraction of tarfile from $@ | tarslip.py:63:7:63:39 | Attribute() | a potentially untrusted source |

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

@@ -65,4 +65,4 @@ def safemembers(members):
     # using `if not (os.path.isabs(entry.name) or ".." in entry.name):`
     # would make the sanitizer work, but for the wrong reasons since out library is a bit broken.
     if not os.path.isabs(entry.name):
-        tar.extract(entry, "/tmp/unpack/") # TODO: FP
+        tar.extract(entry, "/tmp/unpack/")