JS: provide command execution sinks for execa package

javascript/ql/lib/javascript.qll

@@ -123,6 +123,7 @@ import semmle.javascript.frameworks.Request
 import semmle.javascript.frameworks.RxJS
 import semmle.javascript.frameworks.ServerLess
 import semmle.javascript.frameworks.ShellJS
+import semmle.javascript.frameworks.Execa
 import semmle.javascript.frameworks.Snapdragon
 import semmle.javascript.frameworks.SystemCommandExecutors
 import semmle.javascript.frameworks.SQL

javascript/ql/lib/semmle/javascript/frameworks/Execa.qll

@@ -0,0 +1,206 @@
+/**
+ * Models the `execa` library in terms of `FileSystemAccess` and `SystemCommandExecution`.
+ */
+
+import javascript
+import semmle.javascript.security.dataflow.RequestForgeryCustomizations
+
+/**
+ * Provide model for [Execa](https://github.com/sindresorhus/execa) package
+ */
+module Execa {
+  /**
+   * The Execa input file read and output file write
+   */
+  class ExecaFileSystemAccess extends FileSystemReadAccess, DataFlow::Node {
+    API::Node execaArg;
+    boolean isPipedToFile;
+
+    ExecaFileSystemAccess() {
+      (
+        execaArg = API::moduleImport("execa").getMember("$").getParameter(0) and
+        isPipedToFile = false
+        or
+        execaArg =
+          API::moduleImport("execa")
+              .getMember(["execa", "execaCommand", "execaCommandSync", "execaSync"])
+              .getParameter([0, 1, 2]) and
+        isPipedToFile = false
+        or
+        execaArg =
+          API::moduleImport("execa")
+              .getMember(["execa", "execaCommand", "execaCommandSync", "execaSync"])
+              .getReturn()
+              .getMember(["pipeStdout", "pipeAll", "pipeStderr"])
+              .getParameter(0) and
+        isPipedToFile = true
+      ) and
+      this = execaArg.asSink()
+    }
+
+    override DataFlow::Node getADataNode() { none() }
+
+    override DataFlow::Node getAPathArgument() {
+      result = execaArg.getMember("inputFile").asSink() and isPipedToFile = false
+      or
+      result = execaArg.asSink() and isPipedToFile = true
+    }
+  }
+
+  /**
+   * A call to `execa.execa` or `execa.execaSync`
+   */
+  class ExecaCall extends API::CallNode {
+    boolean isSync;
+
+    ExecaCall() {
+      this = API::moduleImport("execa").getMember("execa").getACall() and
+      isSync = false
+      or
+      this = API::moduleImport("execa").getMember("execaSync").getACall() and
+      isSync = true
+    }
+  }
+
+  /**
+   * The system command execution nodes for `execa.execa` or `execa.execaSync` functions
+   */
+  class ExecaExec extends SystemCommandExecution, ExecaCall {
+    ExecaExec() { isSync = [false, true] }
+
+    override DataFlow::Node getACommandArgument() { result = this.getArgument(0) }
+
+    override predicate isShellInterpreted(DataFlow::Node arg) {
+      // if shell: true then first and second args are sinks
+      // options can be third argument
+      arg = [this.getArgument(0), this.getParameter(1).getUnknownMember().asSink()] and
+      isExecaShellEnable(this.getParameter(2))
+      or
+      // options can be second argument
+      arg = this.getArgument(0) and
+      isExecaShellEnable(this.getParameter(1))
+    }
+
+    override DataFlow::Node getArgumentList() {
+      // execa(cmd, [arg]);
+      exists(DataFlow::Node arg | arg = this.getArgument(1) |
+        // if it is a object then it is a option argument not command argument
+        result = arg and not arg.asExpr() instanceof ObjectExpr
+      )
+    }
+
+    override predicate isSync() { isSync = true }
+
+    override DataFlow::Node getOptionsArg() {
+      result = this.getLastArgument() and result.asExpr() instanceof ObjectExpr
+    }
+  }
+
+  /**
+   * A call to `execa.$` or `execa.$.sync` or `execa.$({})` or `execa.$.sync({})` tag functions
+   */
+  private class ExecaScriptCall extends API::CallNode {
+    boolean isSync;
+
+    ExecaScriptCall() {
+      exists(API::Node script |
+        script =
+          [
+            API::moduleImport("execa").getMember("$"),
+            API::moduleImport("execa").getMember("$").getReturn()
+          ]
+      |
+        this = script.getACall() and
+        isSync = false
+        or
+        this = script.getMember("sync").getACall() and
+        isSync = true
+      )
+    }
+  }
+
+  /**
+   * The system command execution nodes for `execa.$` or `execa.$.sync` tag functions
+   */
+  class ExecaScript extends SystemCommandExecution, ExecaScriptCall {
+    ExecaScript() { isSync = [false, true] }
+
+    override DataFlow::Node getACommandArgument() { result = this.getParameter(1).asSink() }
+
+    override predicate isShellInterpreted(DataFlow::Node arg) {
+      isExecaShellEnable(this.getParameter(0)) and
+      arg = this.getAParameter().asSink()
+    }
+
+    override DataFlow::Node getArgumentList() {
+      result = this.getParameter(any(int i | i > 2)).asSink() and
+      // here I should check if the first parameter of Template literal is the rightmost string of this Template literal then the arguments of this command execution will be the second and third and .. parameters
+      not exists(string s | this.getACall().getArgument(0).mayHaveStringValue(s) | s.matches(""))
+      or
+      result = this.getParameter(any(int i | i > 1)).asSink() and
+      // here I should check if the first parameter of Template literal is a constant which is the command, then the arguments of this command execution will be the first, second and third and .. parameters
+      not exists(string s | this.getACall().getArgument(0).mayHaveStringValue(s) | s.matches(""))
+    }
+
+    override DataFlow::Node getOptionsArg() { result = this.getParameter(0).asSink() }
+
+    override predicate isSync() { isSync = true }
+  }
+
+  /**
+   * A call to `execa.execaCommandSync` or `execa.execaCommand`
+   */
+  private class ExecaCommandCall extends API::CallNode {
+    boolean isSync;
+
+    ExecaCommandCall() {
+      this = API::moduleImport("execa").getMember("execaCommandSync").getACall() and
+      isSync = true
+      or
+      this = API::moduleImport("execa").getMember("execaCommand").getACall() and
+      isSync = false
+    }
+  }
+
+  /**
+   * The system command execution nodes for `execa.execaCommand` or `execa.execaCommandSync` functions
+   */
+  class ExecaCommandExec extends SystemCommandExecution, ExecaCommandCall {
+    ExecaCommandExec() { isSync = [false, true] }
+
+    override DataFlow::Node getACommandArgument() {
+      result = this.(DataFlow::CallNode).getArgument(0)
+    }
+
+    override DataFlow::Node getArgumentList() {
+      // execaCommand(`${cmd} ${arg}`);
+      result.asExpr() = this.getParameter(0).asSink().asExpr().getAChildExpr() and
+      not result.asExpr() = this.getArgument(0).asExpr().getChildExpr(0)
+    }
+
+    override predicate isShellInterpreted(DataFlow::Node arg) {
+      // execaCommandSync(`${cmd} ${arg}`, {shell: true})
+      arg.asExpr() = this.getArgument(0).asExpr().getAChildExpr+() and
+      isExecaShellEnable(this.getParameter(1))
+      or
+      // there is only one argument that is constructed in previous nodes,
+      // it makes sanitizing really hard to select whether it is vulnerable to argument injection or not
+      arg = this.getParameter(0).asSink() and
+      not exists(this.getArgument(0).asExpr().getChildExpr(1))
+    }
+
+    override predicate isSync() { isSync = true }
+
+    override DataFlow::Node getOptionsArg() {
+      result = this.getLastArgument() and result.asExpr() instanceof ObjectExpr
+    }
+  }
+
+  /**
+   * Holds whether Execa has shell enabled options or not, get Parameter responsible for options
+   */
+  pragma[inline]
+  private predicate isExecaShellEnable(API::Node n) {
+    n.getMember("shell").asSink().asExpr().(BooleanLiteral).getValue() = "true"
+  }
+}