Add taint-tracking for package os

Author: gagliardetto

ql/src/semmle/go/frameworks/Stdlib.qll

@@ -29,6 +29,7 @@ import semmle.go.frameworks.stdlib.EncodingPem
 import semmle.go.frameworks.stdlib.EncodingXml
 import semmle.go.frameworks.stdlib.Html
 import semmle.go.frameworks.stdlib.HtmlTemplate
+import semmle.go.frameworks.stdlib.Os
 import semmle.go.frameworks.stdlib.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 import semmle.go.frameworks.stdlib.Reflect

ql/src/semmle/go/frameworks/stdlib/Os.qll

@@ -0,0 +1,82 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `os` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `os` package. */
+module Os {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func Expand(s string, mapping func(string) string) string
+      hasQualifiedName("os", "Expand") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func ExpandEnv(s string) string
+      hasQualifiedName("os", "ExpandEnv") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func NewFile(fd uintptr, name string) *File
+      hasQualifiedName("os", "NewFile") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func Pipe() (r *File, w *File, err error)
+      hasQualifiedName("os", "Pipe") and
+      (inp.isResult(1) and outp.isResult(0))
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+
+  private class MethodModels extends TaintTracking::FunctionModel, Method {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    MethodModels() {
+      // signature: func (*File).Fd() uintptr
+      this.hasQualifiedName("os", "File", "Fd") and
+      (inp.isReceiver() and outp.isResult())
+      or
+      // signature: func (*File).Read(b []byte) (n int, err error)
+      this.hasQualifiedName("os", "File", "Read") and
+      (inp.isReceiver() and outp.isParameter(0))
+      or
+      // signature: func (*File).ReadAt(b []byte, off int64) (n int, err error)
+      this.hasQualifiedName("os", "File", "ReadAt") and
+      (inp.isReceiver() and outp.isParameter(0))
+      or
+      // signature: func (*File).ReadFrom(r io.Reader) (n int64, err error)
+      this.hasQualifiedName("os", "File", "ReadFrom") and
+      (inp.isParameter(0) and outp.isReceiver())
+      or
+      // signature: func (*File).SyscallConn() (syscall.RawConn, error)
+      this.hasQualifiedName("os", "File", "SyscallConn") and
+      (
+        inp.isReceiver() and outp.isResult(0)
+        or
+        inp.isResult(0) and outp.isReceiver()
+      )
+      or
+      // signature: func (*File).Write(b []byte) (n int, err error)
+      this.hasQualifiedName("os", "File", "Write") and
+      (inp.isParameter(0) and outp.isReceiver())
+      or
+      // signature: func (*File).WriteAt(b []byte, off int64) (n int, err error)
+      this.hasQualifiedName("os", "File", "WriteAt") and
+      (inp.isParameter(0) and outp.isReceiver())
+      or
+      // signature: func (*File).WriteString(s string) (n int, err error)
+      this.hasQualifiedName("os", "File", "WriteString") and
+      (inp.isParameter(0) and outp.isReceiver())
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}