Rust: Add example queries

docs/codeql/reusables/rust-further-reading.rst

@@ -1,2 +1,3 @@
 - `CodeQL queries for Rust <https://github.com/github/codeql/tree/main/rust/ql/src>`__
+- `Example queries for Rust <https://github.com/github/codeql/tree/main/rust/ql/examples>`__
 - `CodeQL library reference for Rust <https://codeql.github.com/codeql-standard-libraries/rust/>`__

rust/ql/examples/qlpack.lock.yml

@@ -0,0 +1,4 @@
+---
+dependencies: {}
+compiled: false
+lockVersion: 1.0.0

rust/ql/examples/qlpack.yml

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+name: codeql/rust-examples
+groups:
+  - rust
+  - examples
+dependencies:
+  codeql/rust-all: ${workspace}
+warnOnImplicitThis: true

rust/ql/examples/snippets/empty_if.ql

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+/**
+ * @name Empty 'if' statement
+ * @description Finds 'if' statements where the "then" branch is empty and no
+ *              "else" branch exists.
+ * @id rust/examples/empty-if
+ * @tags example
+ */
+
+import rust
+
+// find 'if' statements...
+from IfExpr ifExpr
+where
+  // where the 'then' branch is empty
+  ifExpr.getThen().(BlockExpr).getStmtList().getNumberOfStmtOrExpr() = 0 and
+  // and no 'else' branch exists
+  not exists(ifExpr.getElse())
+select ifExpr, "This 'if' expression is redundant."

rust/ql/examples/snippets/simple_constant_password.ql

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+/**
+ * @name Constant password
+ * @description Finds places where a string literal is used in a function call
+ *              argument that looks like a password.
+ * @id rust/examples/simple-constant-password
+ * @tags example
+ */
+
+import rust
+import codeql.rust.dataflow.DataFlow
+import codeql.rust.dataflow.TaintTracking
+
+/**
+ * A data flow configuration for tracking flow from a string literal to a function
+ * call argument that looks like a password. For example:
+ * ```
+ * fn set_password(password: &str) { ... }
+ *
+ * ...
+ *
+ * let pwd = "123456"; // source
+ * set_password(pwd); // sink (argument 0)
+ * ```
+ */
+module ConstantPasswordConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node node) {
+    // `node` is a string literal
+    node.asExpr().getExpr() instanceof StringLiteralExpr
+  }
+
+  predicate isSink(DataFlow::Node node) {
+    // `node` is an argument whose corresponding parameter name matches the pattern "pass%"
+    exists(CallExpr call, Function target, int argIndex |
+      call.getStaticTarget() = target and
+      target.getParam(argIndex).getPat().(IdentPat).getName().getText().matches("pass%") and
+      call.getArg(argIndex) = node.asExpr().getExpr()
+    )
+  }
+}
+
+// instantiate the data flow configuration as a global taint tracking module
+module ConstantPasswordFlow = TaintTracking::Global<ConstantPasswordConfig>;
+
+// report flows from sources to sinks
+from DataFlow::Node sourceNode, DataFlow::Node sinkNode
+where ConstantPasswordFlow::flow(sourceNode, sinkNode)
+select sinkNode, "The value $@ is used as a constant password.", sourceNode, sourceNode.toString()

rust/ql/examples/snippets/simple_sql_injection.ql

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+/**
+ * @name Database query built from user-controlled sources
+ * @description Finds places where a value from a remote or local user input
+ *              is used as the first argument of a call to `sqlx_core::query::query`.
+ * @id rust/examples/simple-sql-injection
+ * @tags example
+ */
+
+import rust
+import codeql.rust.dataflow.DataFlow
+import codeql.rust.dataflow.TaintTracking
+import codeql.rust.Concepts
+
+/**
+ * A data flow configuration for tracking flow from a user input (threat model
+ * source) to the first argument of a call to `sqlx_core::query::query`.
+ */
+module SqlInjectionConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node node) {
+    // `node` is a user input (threat model source)
+    node instanceof ActiveThreatModelSource
+  }
+
+  predicate isSink(DataFlow::Node node) {
+    // `node` is the first argument of a call to `sqlx_core::query::query`
+    exists(CallExpr call |
+      call.getStaticTarget().getCanonicalPath() = "sqlx_core::query::query" and
+      call.getArg(0) = node.asExpr().getExpr()
+    )
+  }
+}
+
+// instantiate the data flow configuration as a global taint tracking module
+module SqlInjectionFlow = TaintTracking::Global<SqlInjectionConfig>;
+
+// report flows from sources to sinks
+from DataFlow::Node sourceNode, DataFlow::Node sinkNode
+where SqlInjectionFlow::flow(sourceNode, sinkNode)
+select sinkNode, "This query depends on a $@.", sourceNode, "user-provided value"

rust/ql/src/change-notes/2025-11-07-example-queries.md

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+---
+category: newQuery
+---
+* Added three example queries (`rust/examples/empty-if`, `rust/examples/simple-sql-injection` and `rust/examples/simple-constant-password`) to help developers learn to write CodeQL queries for Rust.