Rust: Improve rust/ctor-initialization

rust/ql/src/queries/security/CWE-696/BadCtorInitialization.ql

@@ -14,7 +14,7 @@
 import rust
 
 /**
- * A `#[ctor]` or `#[dtor]` attribute.
+ * A `#[ctor]` or `#[dtor]` attribute, that is, a source for this query.
  */
 class CtorAttr extends Attr {
   string whichAttr;
@@ -28,7 +28,7 @@ class CtorAttr extends Attr {
 }
 
 /**
- * A call into the Rust standard library.
+ * A call into the Rust standard library, that is, a sink for this query.
  */
 class StdCall extends Expr {
   StdCall() {
@@ -39,20 +39,38 @@ class StdCall extends Expr {
 
 class PathElement = AstNode;
 
+/**
+ * Holds if (`pred`, `succ`) represents a candidate edge for the query that is
+ * reachable from a source.
+ */
+predicate edgesFwd(PathElement pred, PathElement succ) {
+  // attribute (source) -> callable
+  pred.(CtorAttr) = succ.(Callable).getAnAttr()
+  or
+  // [forwards reachable] callable -> enclosed call
+  edgesFwd(_, pred) and
+  pred = succ.(CallExprBase).getEnclosingCallable()
+  or
+  // [forwards reachable] call -> target callable
+  edgesFwd(_, pred) and
+  pred.(CallExprBase).getStaticTarget() = succ
+}
+
+/**
+ * Holds if (`pred`, `succ`) represents an edge for the query that is reachable
+ * from a source and backwards reachable from a sink (adding the backwards
+ * reachability constraint reduces the amount of output data produced).
+ */
 query predicate edges(PathElement pred, PathElement succ) {
-  // starting edge
-  exists(CtorAttr ctor, Function f, StdCall call |
-    f.getAnAttr() = ctor and
-    call.getEnclosingCallable() = f and
-    pred = ctor and // source
-    succ = call // sink
+  edgesFwd(pred, succ) and
+  (
+    succ instanceof StdCall // sink
+    or
+    edges(succ, _) // backwards reachable from a sink
   )
-  // or
-  // transitive edge
-  // TODO
 }
 
-from CtorAttr ctor, StdCall call
-where edges*(ctor, call)
-select call, ctor, call,
-  "Call to " + call.toString() + " in a function with the " + ctor.getWhichAttr() + " attribute."
+from CtorAttr source, StdCall sink
+where edges+(source, sink)
+select sink, source, sink,
+  "Call to " + sink.toString() + " in a function with the " + source.getWhichAttr() + " attribute."

rust/ql/test/query-tests/security/CWE-696/BadCTorInitialization.expected

@@ -8,15 +8,37 @@
 | test.rs:69:9:69:24 | ...::stdin(...) | test.rs:66:1:66:7 | Attr | test.rs:69:9:69:24 | ...::stdin(...) | Call to ...::stdin(...) in a function with the ctor attribute. |
 | test.rs:90:5:90:35 | ...::sleep(...) | test.rs:88:1:88:7 | Attr | test.rs:90:5:90:35 | ...::sleep(...) | Call to ...::sleep(...) in a function with the ctor attribute. |
 | test.rs:97:5:97:23 | ...::exit(...) | test.rs:95:1:95:7 | Attr | test.rs:97:5:97:23 | ...::exit(...) | Call to ...::exit(...) in a function with the ctor attribute. |
-| test.rs:166:5:166:15 | ...::stdout(...) | test.rs:164:1:164:7 | Attr | test.rs:166:5:166:15 | ...::stdout(...) | Call to ...::stdout(...) in a function with the ctor attribute. |
+| test.rs:126:9:126:16 | stderr(...) | test.rs:129:1:129:7 | Attr | test.rs:126:9:126:16 | stderr(...) | Call to stderr(...) in a function with the ctor attribute. |
+| test.rs:126:9:126:16 | stderr(...) | test.rs:145:1:145:7 | Attr | test.rs:126:9:126:16 | stderr(...) | Call to stderr(...) in a function with the ctor attribute. |
+| test.rs:126:9:126:44 | ... .write_all(...) | test.rs:129:1:129:7 | Attr | test.rs:126:9:126:44 | ... .write_all(...) | Call to ... .write_all(...) in a function with the ctor attribute. |
+| test.rs:126:9:126:44 | ... .write_all(...) | test.rs:145:1:145:7 | Attr | test.rs:126:9:126:44 | ... .write_all(...) | Call to ... .write_all(...) in a function with the ctor attribute. |
+| test.rs:171:5:171:15 | ...::stdout(...) | test.rs:169:1:169:7 | Attr | test.rs:171:5:171:15 | ...::stdout(...) | Call to ...::stdout(...) in a function with the ctor attribute. |
 edges
-| test.rs:29:1:29:13 | Attr | test.rs:31:9:31:25 | ...::stdout(...) |
-| test.rs:34:1:34:13 | Attr | test.rs:36:9:36:25 | ...::stdout(...) |
-| test.rs:40:1:40:13 | Attr | test.rs:43:9:43:25 | ...::stdout(...) |
-| test.rs:51:1:51:7 | Attr | test.rs:53:9:53:16 | stdout(...) |
-| test.rs:56:1:56:7 | Attr | test.rs:58:9:58:16 | stderr(...) |
-| test.rs:61:1:61:7 | Attr | test.rs:63:14:63:28 | ...::_print(...) |
-| test.rs:66:1:66:7 | Attr | test.rs:69:9:69:24 | ...::stdin(...) |
-| test.rs:88:1:88:7 | Attr | test.rs:90:5:90:35 | ...::sleep(...) |
-| test.rs:95:1:95:7 | Attr | test.rs:97:5:97:23 | ...::exit(...) |
-| test.rs:164:1:164:7 | Attr | test.rs:166:5:166:15 | ...::stdout(...) |
+| test.rs:29:1:29:13 | Attr | test.rs:29:1:32:1 | fn bad1_1 |
+| test.rs:29:1:32:1 | fn bad1_1 | test.rs:31:9:31:25 | ...::stdout(...) |
+| test.rs:34:1:34:13 | Attr | test.rs:34:1:37:1 | fn bad1_2 |
+| test.rs:34:1:37:1 | fn bad1_2 | test.rs:36:9:36:25 | ...::stdout(...) |
+| test.rs:39:1:44:1 | fn bad1_3 | test.rs:43:9:43:25 | ...::stdout(...) |
+| test.rs:40:1:40:13 | Attr | test.rs:39:1:44:1 | fn bad1_3 |
+| test.rs:51:1:51:7 | Attr | test.rs:51:1:54:1 | fn bad2_1 |
+| test.rs:51:1:54:1 | fn bad2_1 | test.rs:53:9:53:16 | stdout(...) |
+| test.rs:56:1:56:7 | Attr | test.rs:56:1:59:1 | fn bad2_2 |
+| test.rs:56:1:59:1 | fn bad2_2 | test.rs:58:9:58:16 | stderr(...) |
+| test.rs:61:1:61:7 | Attr | test.rs:61:1:64:1 | fn bad2_3 |
+| test.rs:61:1:64:1 | fn bad2_3 | test.rs:63:14:63:28 | ...::_print(...) |
+| test.rs:66:1:66:7 | Attr | test.rs:66:1:70:1 | fn bad2_4 |
+| test.rs:66:1:70:1 | fn bad2_4 | test.rs:69:9:69:24 | ...::stdin(...) |
+| test.rs:88:1:88:7 | Attr | test.rs:88:1:91:1 | fn bad2_7 |
+| test.rs:88:1:91:1 | fn bad2_7 | test.rs:90:5:90:35 | ...::sleep(...) |
+| test.rs:95:1:95:7 | Attr | test.rs:95:1:98:1 | fn bad2_8 |
+| test.rs:95:1:98:1 | fn bad2_8 | test.rs:97:5:97:23 | ...::exit(...) |
+| test.rs:125:1:127:1 | fn call_target3_1 | test.rs:126:9:126:16 | stderr(...) |
+| test.rs:125:1:127:1 | fn call_target3_1 | test.rs:126:9:126:44 | ... .write_all(...) |
+| test.rs:129:1:129:7 | Attr | test.rs:129:1:132:1 | fn bad3_1 |
+| test.rs:129:1:132:1 | fn bad3_1 | test.rs:131:5:131:20 | call_target3_1(...) |
+| test.rs:131:5:131:20 | call_target3_1(...) | test.rs:125:1:127:1 | fn call_target3_1 |
+| test.rs:145:1:145:7 | Attr | test.rs:145:1:149:1 | fn bad3_3 |
+| test.rs:145:1:149:1 | fn bad3_3 | test.rs:147:5:147:20 | call_target3_1(...) |
+| test.rs:147:5:147:20 | call_target3_1(...) | test.rs:125:1:127:1 | fn call_target3_1 |
+| test.rs:169:1:169:7 | Attr | test.rs:169:1:172:1 | fn bad4_1 |
+| test.rs:169:1:172:1 | fn bad4_1 | test.rs:171:5:171:15 | ...::stdout(...) |

rust/ql/test/query-tests/security/CWE-696/test.rs

@@ -123,10 +123,10 @@ unsafe fn harmless2_11() {
 // --- transitive cases ---
 
 fn call_target3_1() {
-    _ = stderr().write_all(b"Hello, world!"); // $ MISSING: Alert=source3_1 Alert=source3_3 Alert=source3_4
+    _ = stderr().write_all(b"Hello, world!"); // $ Alert=source3_1 Alert=source3_3 MISSING: Alert=source3_4
 }
 
-#[ctor] // $ MISSING: Source=source3_1
+#[ctor] // $ Source=source3_1
 fn bad3_1() {
     call_target3_1();
 }
@@ -137,12 +137,12 @@ fn call_target3_2() {
     }
 }
 
-#[ctor] // $ MISSING: Source=source3_2
+#[ctor]
 fn harmless3_2() {
     call_target3_2();
 }
 
-#[ctor]
+#[ctor] // $ Source=source3_3
 fn bad3_3() {
     call_target3_1();
     call_target3_2();
@@ -153,6 +153,11 @@ fn bad3_4() {
     bad3_3();
 }
 
+fn harmless3_5() {
+    call_target3_1();
+    call_target3_2();
+}
+
 // --- macros ---
 
 macro_rules! macro4_1 {