From e692af21ac168b94c34758c6b6efd9904c60c00a Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 24 Jun 2020 07:09:09 +0100
Subject: [PATCH 01/10] Extend model of `glog` to also cover two API-compatible
 forks.

---
 ql/src/go.qll                        |  1 +
 ql/src/semmle/go/frameworks/Glog.qll | 28 ++++++++++++++--------------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/ql/src/go.qll b/ql/src/go.qll
index 4438f9be89b..512fd06d05c 100644
--- a/ql/src/go.qll
+++ b/ql/src/go.qll
@@ -26,6 +26,7 @@ import semmle.go.dataflow.GlobalValueNumbering
 import semmle.go.dataflow.SSA
 import semmle.go.dataflow.TaintTracking
 import semmle.go.frameworks.Email
+import semmle.go.frameworks.Glog
 import semmle.go.frameworks.HTTP
 import semmle.go.frameworks.Macaron
 import semmle.go.frameworks.Mux
diff --git a/ql/src/semmle/go/frameworks/Glog.qll b/ql/src/semmle/go/frameworks/Glog.qll
index bb800911751..a48670a135b 100644
--- a/ql/src/semmle/go/frameworks/Glog.qll
+++ b/ql/src/semmle/go/frameworks/Glog.qll
@@ -1,25 +1,25 @@
-/** Provides models of commonly used functions in the `github.com/golang/glog` package. */
+/**
+ * Provides models of commonly used functions in the `github.com/golang/glog` and `k8s.io/klog`
+ * packages.
+ */
 
 import go
 
-/** Provides models of commonly used functions in the `github.com/golang/glog` package. */
+/**
+ * Provides models of commonly used functions in the `github.com/golang/glog` packages and its
+ * forks.
+ */
 module Glog {
   private class GlogCall extends LoggerCall::Range, DataFlow::CallNode {
     GlogCall() {
-      exists(string fn |
-        fn.regexpMatch("Error(|f|ln)")
-        or
-        fn.regexpMatch("Exit(|f|ln)")
-        or
-        fn.regexpMatch("Fatal(|f|ln)")
-        or
-        fn.regexpMatch("Info(|f|ln)")
-        or
-        fn.regexpMatch("Warning(|f|ln)")
+      exists(string pkg, Function f, string fn |
+        pkg = package(["github.com/golang/glog", "gopkg.in/glog", "k8s.io/klog"], "") and
+        fn.regexpMatch("(Error|Exit|Fatal|Info|Warning)(|f|ln)") and
+        this = f.getACall()
       |
-        this.getTarget().hasQualifiedName("github.com/golang/glog", fn)
+        f.hasQualifiedName(pkg, fn)
         or
-        this.getTarget().(Method).hasQualifiedName("github.com/golang/glog", "Verbose", fn)
+        f.(Method).hasQualifiedName(pkg, "Verbose", fn)
       )
     }
 

From e6a44d45783cd943bd64d2922266e065c7e411f0 Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 24 Jun 2020 07:09:32 +0100
Subject: [PATCH 02/10] Add HTTP-request headers as a source for clear-text
 logging.

---
 .../go/security/CleartextLoggingCustomizations.qll   | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
index fbd35bfbe28..31a2a99b36e 100644
--- a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
+++ b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
@@ -148,4 +148,16 @@ module CleartextLogging {
 
     override string describe() { result = "a call to " + name }
   }
+
+  /** The headers of an HTTP request, considered as a source of sensitive information. */
+  private class RequestHeaderSource extends Source {
+    RequestHeaderSource() {
+      exists(Field hdr |
+        hdr.hasQualifiedName("net/http", "Request", "Header") and
+        this = hdr.getARead()
+      )
+    }
+
+    override string describe() { result = "HTTP request headers" }
+  }
 }

From ef340954e42204a3a3d5bd58785812e2e402d144 Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 24 Jun 2020 07:10:03 +0100
Subject: [PATCH 03/10] Add `mask*` as a heuristic name for an obfuscating
 function.

---
 ql/src/semmle/go/security/SensitiveActions.qll | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ql/src/semmle/go/security/SensitiveActions.qll b/ql/src/semmle/go/security/SensitiveActions.qll
index caeb62f35a7..36922e4416f 100644
--- a/ql/src/semmle/go/security/SensitiveActions.qll
+++ b/ql/src/semmle/go/security/SensitiveActions.qll
@@ -55,7 +55,8 @@ module HeuristicNames {
    * that is hashed, encrypted, or a test value, and hence non-sensitive.
    */
   string notSensitive() {
-    result = "(?is).*(test|redact|censor|obfuscate|hash|md5|sha|((?<!un)(en))?(crypt|code)).*"
+    result =
+      "(?is).*(test|redact|censor|obfuscate|hash|md5|(?<!un)mask|sha|((?<!un)(en))?(crypt|code)).*"
   }
 }
 

From df4265e31bbd56b17b7a89c78434c24360fe922d Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 24 Jun 2020 07:33:17 +0100
Subject: [PATCH 04/10] Add more tests for clear-text logging.

---
 .../CWE-312/CleartextLogging.expected         |   6 +
 ql/test/query-tests/Security/CWE-312/go.mod   |   1 +
 ql/test/query-tests/Security/CWE-312/klog.go  |  28 +++
 .../vendor/github.com/golang/glog/stub.go     |   1 +
 .../vendor/github.com/sirupsen/logrus/stub.go |  37 +---
 .../CWE-312/vendor/k8s.io/klog/LICENSE        | 191 ++++++++++++++++++
 .../CWE-312/vendor/k8s.io/klog/stub.go        |  12 ++
 .../Security/CWE-312/vendor/modules.txt       |   3 +
 8 files changed, 252 insertions(+), 27 deletions(-)
 create mode 100644 ql/test/query-tests/Security/CWE-312/klog.go
 create mode 100644 ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/LICENSE
 create mode 100644 ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/stub.go

diff --git a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
index 4fca314327d..4d797f8be5d 100644
--- a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
+++ b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
@@ -1,4 +1,5 @@
 edges
+| klog.go:20:30:20:37 | selection of Header : Header | klog.go:22:15:22:20 | header |
 | passwords.go:8:12:8:12 | definition of x : string | passwords.go:9:14:9:14 | x |
 | passwords.go:30:8:30:15 | password : string | passwords.go:8:12:8:12 | definition of x : string |
 | passwords.go:34:28:34:35 | password : string | passwords.go:34:14:34:35 | ...+... |
@@ -22,7 +23,10 @@ edges
 | passwords.go:127:14:127:19 | config [y] : string | passwords.go:127:14:127:21 | selection of y |
 | util.go:16:9:16:18 | selection of password : string | passwords.go:28:14:28:28 | call to getPassword |
 nodes
+| klog.go:20:30:20:37 | selection of Header : Header | semmle.label | selection of Header : Header |
+| klog.go:22:15:22:20 | header | semmle.label | header |
 | main.go:15:14:15:21 | password | semmle.label | password |
+| main.go:17:12:17:19 | password | semmle.label | password |
 | passwords.go:8:12:8:12 | definition of x : string | semmle.label | definition of x : string |
 | passwords.go:9:14:9:14 | x | semmle.label | x |
 | passwords.go:25:14:25:21 | password | semmle.label | password |
@@ -64,7 +68,9 @@ nodes
 | passwords.go:127:14:127:21 | selection of y | semmle.label | selection of y |
 | util.go:16:9:16:18 | selection of password : string | semmle.label | selection of password : string |
 #select
+| klog.go:22:15:22:20 | header | klog.go:20:30:20:37 | selection of Header : Header | klog.go:22:15:22:20 | header | Sensitive data returned by $@ is logged here. | klog.go:20:30:20:37 | selection of Header | HTTP request headers |
 | main.go:15:14:15:21 | password | main.go:15:14:15:21 | password | main.go:15:14:15:21 | password | Sensitive data returned by $@ is logged here. | main.go:15:14:15:21 | password | an access to password |
+| main.go:17:12:17:19 | password | main.go:17:12:17:19 | password | main.go:17:12:17:19 | password | Sensitive data returned by $@ is logged here. | main.go:17:12:17:19 | password | an access to password |
 | passwords.go:9:14:9:14 | x | passwords.go:30:8:30:15 | password : string | passwords.go:9:14:9:14 | x | Sensitive data returned by $@ is logged here. | passwords.go:30:8:30:15 | password | an access to password |
 | passwords.go:25:14:25:21 | password | passwords.go:25:14:25:21 | password | passwords.go:25:14:25:21 | password | Sensitive data returned by $@ is logged here. | passwords.go:25:14:25:21 | password | an access to password |
 | passwords.go:26:14:26:23 | selection of password | passwords.go:26:14:26:23 | selection of password | passwords.go:26:14:26:23 | selection of password | Sensitive data returned by $@ is logged here. | passwords.go:26:14:26:23 | selection of password | an access to password |
diff --git a/ql/test/query-tests/Security/CWE-312/go.mod b/ql/test/query-tests/Security/CWE-312/go.mod
index d56c33ffc85..7dbd14e13e0 100644
--- a/ql/test/query-tests/Security/CWE-312/go.mod
+++ b/ql/test/query-tests/Security/CWE-312/go.mod
@@ -5,4 +5,5 @@ go 1.14
 require (
 	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b
 	github.com/sirupsen/logrus v1.5.0
+	k8s.io/klog v1.0.0
 )
diff --git a/ql/test/query-tests/Security/CWE-312/klog.go b/ql/test/query-tests/Security/CWE-312/klog.go
new file mode 100644
index 00000000000..ee0cf9df549
--- /dev/null
+++ b/ql/test/query-tests/Security/CWE-312/klog.go
@@ -0,0 +1,28 @@
+package main
+
+//go:generate depstubber -vendor k8s.io/klog "" Info
+
+import (
+	"k8s.io/klog"
+	"net/http"
+	"strings"
+)
+
+func mask(key, value string) string {
+	if strings.EqualFold(key, "Authorization") {
+		return "<masked>"
+	}
+	return value
+}
+
+func klogTest() {
+	http.HandleFunc("/klog", func(w http.ResponseWriter, r *http.Request) {
+		for name, headers := range r.Header {
+			for _, header := range headers {
+				klog.Info(header)             // NOT OK
+				klog.Info(mask(name, header)) // OK
+			}
+		}
+	})
+	http.ListenAndServe(":80", nil)
+}
diff --git a/ql/test/query-tests/Security/CWE-312/vendor/github.com/golang/glog/stub.go b/ql/test/query-tests/Security/CWE-312/vendor/github.com/golang/glog/stub.go
index 9e1c7e69fed..cdd12b34901 100644
--- a/ql/test/query-tests/Security/CWE-312/vendor/github.com/golang/glog/stub.go
+++ b/ql/test/query-tests/Security/CWE-312/vendor/github.com/golang/glog/stub.go
@@ -1,6 +1,7 @@
 // Code generated by depstubber. DO NOT EDIT.
 // This is a simple stub for github.com/golang/glog, strictly for use in testing.
 
+// See the LICENSE file for information about the licensing of the original library.
 // Source: github.com/golang/glog (exports: ; functions: Info)
 
 // Package glog is a stub of github.com/golang/glog, generated by depstubber.
diff --git a/ql/test/query-tests/Security/CWE-312/vendor/github.com/sirupsen/logrus/stub.go b/ql/test/query-tests/Security/CWE-312/vendor/github.com/sirupsen/logrus/stub.go
index fc5e9fd6736..84859e578f2 100644
--- a/ql/test/query-tests/Security/CWE-312/vendor/github.com/sirupsen/logrus/stub.go
+++ b/ql/test/query-tests/Security/CWE-312/vendor/github.com/sirupsen/logrus/stub.go
@@ -1,6 +1,7 @@
 // Code generated by depstubber. DO NOT EDIT.
 // This is a simple stub for github.com/sirupsen/logrus, strictly for use in testing.
 
+// See the LICENSE file for information about the licensing of the original library.
 // Source: github.com/sirupsen/logrus (exports: Fields,Entry; functions: Warning,WithFields,WithField)
 
 // Package logrus is a stub of github.com/sirupsen/logrus, generated by depstubber.
@@ -29,9 +30,7 @@ func (_ Entry) HasCaller() bool {
 	return false
 }
 
-func (_ *Entry) Bytes() ([]uint8, interface {
-	Error() string
-}) {
+func (_ *Entry) Bytes() ([]byte, error) {
 	return nil, nil
 }
 
@@ -77,9 +76,7 @@ func (_ *Entry) Printf(_ string, _ ...interface{}) {}
 
 func (_ *Entry) Println(_ ...interface{}) {}
 
-func (_ *Entry) String() (string, interface {
-	Error() string
-}) {
+func (_ *Entry) String() (string, error) {
 	return "", nil
 }
 
@@ -105,9 +102,7 @@ func (_ *Entry) WithContext(_ context.Context) *Entry {
 	return nil
 }
 
-func (_ *Entry) WithError(_ interface {
-	Error() string
-}) *Entry {
+func (_ *Entry) WithError(_ error) *Entry {
 	return nil
 }
 
@@ -134,23 +129,17 @@ func (_ *Entry) WriterLevel(_ Level) *io.PipeWriter {
 type Fields map[string]interface{}
 
 type Formatter interface {
-	Format(_ *Entry) ([]uint8, interface {
-		Error() string
-	})
+	Format(_ *Entry) ([]byte, error)
 }
 
 type Hook interface {
-	Fire(_ *Entry) interface {
-		Error() string
-	}
+	Fire(_ *Entry) error
 	Levels() []Level
 }
 
 type Level uint32
 
-func (_ Level) MarshalText() ([]uint8, interface {
-	Error() string
-}) {
+func (_ Level) MarshalText() ([]byte, error) {
 	return nil, nil
 }
 
@@ -158,9 +147,7 @@ func (_ Level) String() string {
 	return ""
 }
 
-func (_ *Level) UnmarshalText(_ []uint8) interface {
-	Error() string
-} {
+func (_ *Level) UnmarshalText(_ []byte) error {
 	return nil
 }
 
@@ -168,9 +155,7 @@ type LevelHooks map[Level][]Hook
 
 func (_ LevelHooks) Add(_ Hook) {}
 
-func (_ LevelHooks) Fire(_ Level, _ *Entry) interface {
-	Error() string
-} {
+func (_ LevelHooks) Fire(_ Level, _ *Entry) error {
 	return nil
 }
 
@@ -273,9 +258,7 @@ func (_ *Logger) WithContext(_ context.Context) *Entry {
 	return nil
 }
 
-func (_ *Logger) WithError(_ interface {
-	Error() string
-}) *Entry {
+func (_ *Logger) WithError(_ error) *Entry {
 	return nil
 }
 
diff --git a/ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/LICENSE b/ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/LICENSE
new file mode 100644
index 00000000000..37ec93a14fd
--- /dev/null
+++ b/ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/LICENSE
@@ -0,0 +1,191 @@
+Apache License
+Version 2.0, January 2004
+http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
+"License" shall mean the terms and conditions for use, reproduction, and
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diff --git a/ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/stub.go b/ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/stub.go
new file mode 100644
index 00000000000..7dbaa5001fc
--- /dev/null
+++ b/ql/test/query-tests/Security/CWE-312/vendor/k8s.io/klog/stub.go
@@ -0,0 +1,12 @@
+// Code generated by depstubber. DO NOT EDIT.
+// This is a simple stub for k8s.io/klog, strictly for use in testing.
+
+// See the LICENSE file for information about the licensing of the original library.
+// Source: k8s.io/klog (exports: ; functions: Info)
+
+// Package klog is a stub of k8s.io/klog, generated by depstubber.
+package klog
+
+import ()
+
+func Info(_ ...interface{}) {}
diff --git a/ql/test/query-tests/Security/CWE-312/vendor/modules.txt b/ql/test/query-tests/Security/CWE-312/vendor/modules.txt
index b0149947f41..911000aac9e 100644
--- a/ql/test/query-tests/Security/CWE-312/vendor/modules.txt
+++ b/ql/test/query-tests/Security/CWE-312/vendor/modules.txt
@@ -4,3 +4,6 @@ github.com/golang/glog
 # github.com/sirupsen/logrus v1.5.0
 ## explicit
 github.com/sirupsen/logrus
+# k8s.io/klog v1.0.0
+## explicit
+k8s.io/klog

From c80314a3fb95428652e953887513409b3683841e Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Tue, 30 Jun 2020 09:27:48 +0100
Subject: [PATCH 05/10] Treat non-sensitive header retrieval as a barrier.

---
 .../CleartextLoggingCustomizations.qll        | 21 +++++++++++++++++++
 .../CWE-312/CleartextLogging.expected         |  4 ++++
 ql/test/query-tests/Security/CWE-312/klog.go  |  3 +++
 3 files changed, 28 insertions(+)

diff --git a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
index 31a2a99b36e..d5137dd4116 100644
--- a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
+++ b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
@@ -84,6 +84,27 @@ module CleartextLogging {
     ObfuscatorCall() { this.getCalleeName().regexpMatch(notSensitive()) }
   }
 
+  /**
+   * Read of a non-sensitive header, considered as a barrier for clear-text logging.
+   */
+  private class NonSensitiveHeaderGet extends Barrier {
+    NonSensitiveHeaderGet() {
+      exists(string headerName |
+        exists(DataFlow::MethodCallNode c | c = this |
+          c.getTarget().hasQualifiedName("net/http", "Header", "Get") and
+          headerName = c.getArgument(0).getStringValue()
+        )
+        or
+        exists(DataFlow::ElementReadNode e | e = this |
+          e.getBase().getType().hasQualifiedName("net/http", "Header") and
+          headerName = e.getIndex().getStringValue()
+        )
+      |
+        not headerName.toLowerCase() in ["authorization", "cookie"]
+      )
+    }
+  }
+
   /**
    * A data-flow node that does not contain a clear-text password.
    */
diff --git a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
index 4d797f8be5d..8196110a435 100644
--- a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
+++ b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
@@ -1,5 +1,6 @@
 edges
 | klog.go:20:30:20:37 | selection of Header : Header | klog.go:22:15:22:20 | header |
+| klog.go:28:13:28:20 | selection of Header : Header | klog.go:28:13:28:41 | call to Get |
 | passwords.go:8:12:8:12 | definition of x : string | passwords.go:9:14:9:14 | x |
 | passwords.go:30:8:30:15 | password : string | passwords.go:8:12:8:12 | definition of x : string |
 | passwords.go:34:28:34:35 | password : string | passwords.go:34:14:34:35 | ...+... |
@@ -25,6 +26,8 @@ edges
 nodes
 | klog.go:20:30:20:37 | selection of Header : Header | semmle.label | selection of Header : Header |
 | klog.go:22:15:22:20 | header | semmle.label | header |
+| klog.go:28:13:28:20 | selection of Header : Header | semmle.label | selection of Header : Header |
+| klog.go:28:13:28:41 | call to Get | semmle.label | call to Get |
 | main.go:15:14:15:21 | password | semmle.label | password |
 | main.go:17:12:17:19 | password | semmle.label | password |
 | passwords.go:8:12:8:12 | definition of x : string | semmle.label | definition of x : string |
@@ -69,6 +72,7 @@ nodes
 | util.go:16:9:16:18 | selection of password : string | semmle.label | selection of password : string |
 #select
 | klog.go:22:15:22:20 | header | klog.go:20:30:20:37 | selection of Header : Header | klog.go:22:15:22:20 | header | Sensitive data returned by $@ is logged here. | klog.go:20:30:20:37 | selection of Header | HTTP request headers |
+| klog.go:28:13:28:41 | call to Get | klog.go:28:13:28:20 | selection of Header : Header | klog.go:28:13:28:41 | call to Get | Sensitive data returned by $@ is logged here. | klog.go:28:13:28:20 | selection of Header | HTTP request headers |
 | main.go:15:14:15:21 | password | main.go:15:14:15:21 | password | main.go:15:14:15:21 | password | Sensitive data returned by $@ is logged here. | main.go:15:14:15:21 | password | an access to password |
 | main.go:17:12:17:19 | password | main.go:17:12:17:19 | password | main.go:17:12:17:19 | password | Sensitive data returned by $@ is logged here. | main.go:17:12:17:19 | password | an access to password |
 | passwords.go:9:14:9:14 | x | passwords.go:30:8:30:15 | password : string | passwords.go:9:14:9:14 | x | Sensitive data returned by $@ is logged here. | passwords.go:30:8:30:15 | password | an access to password |
diff --git a/ql/test/query-tests/Security/CWE-312/klog.go b/ql/test/query-tests/Security/CWE-312/klog.go
index ee0cf9df549..43203ecdd76 100644
--- a/ql/test/query-tests/Security/CWE-312/klog.go
+++ b/ql/test/query-tests/Security/CWE-312/klog.go
@@ -23,6 +23,9 @@ func klogTest() {
 				klog.Info(mask(name, header)) // OK
 			}
 		}
+		klog.Info(r.Header.Get("Accept")) // OK
+		klog.Info(r.Header["Content-Type"]) // OK
+		klog.Info(r.Header.Get("Authorization")) // NOT OK
 	})
 	http.ListenAndServe(":80", nil)
 }

From 25c969d14c18ede87b628a73e88b082eeff054ae Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Tue, 30 Jun 2020 09:28:06 +0100
Subject: [PATCH 06/10] Model message components for `Fprintf` and friends more
 precisely.

---
 ql/src/semmle/go/frameworks/Stdlib.qll | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/ql/src/semmle/go/frameworks/Stdlib.qll b/ql/src/semmle/go/frameworks/Stdlib.qll
index f14b0fbb45e..7952be8019a 100644
--- a/ql/src/semmle/go/frameworks/Stdlib.qll
+++ b/ql/src/semmle/go/frameworks/Stdlib.qll
@@ -96,9 +96,17 @@ module Fmt {
 
   /** A call to `Print`, `Fprint`, or similar. */
   private class PrintCall extends LoggerCall::Range, DataFlow::CallNode {
-    PrintCall() { this.getTarget() instanceof Printer or this.getTarget() instanceof Fprinter }
+    int firstPrintedArg;
 
-    override DataFlow::Node getAMessageComponent() { result = this.getAnArgument() }
+    PrintCall() {
+      this.getTarget() instanceof Printer and firstPrintedArg = 0
+      or
+      this.getTarget() instanceof Fprinter and firstPrintedArg = 1
+    }
+
+    override DataFlow::Node getAMessageComponent() {
+      result = this.getArgument(any(int i | i >= firstPrintedArg))
+    }
   }
 
   /** The `Fprint` function or one of its variants. */

From 7b903dd0625c53172357b55cdaf3c352cfe7cd2d Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 1 Jul 2020 17:32:51 +0100
Subject: [PATCH 07/10] Teach `CleartextLogging` not to track through
 `error.Error()` and `fmt.Stringer.String()`.

These two are very heavily overloaded and cause all sorts of false positives.
---
 ql/src/semmle/go/security/CleartextLogging.qll         | 10 +++++++++-
 .../Security/CWE-312/CleartextLogging.expected         |  4 ++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/ql/src/semmle/go/security/CleartextLogging.qll b/ql/src/semmle/go/security/CleartextLogging.qll
index 21e2f4bd1ce..1d864705149 100644
--- a/ql/src/semmle/go/security/CleartextLogging.qll
+++ b/ql/src/semmle/go/security/CleartextLogging.qll
@@ -32,7 +32,15 @@ module CleartextLogging {
 
     override predicate isSink(DataFlow::Node sink) { sink instanceof Sink }
 
-    override predicate isBarrier(DataFlow::Node node) { node instanceof Barrier }
+    override predicate isBarrier(DataFlow::Node node) {
+      node instanceof Barrier
+      or
+      exists(DataFlow::CallNode call | node = call.getResult() |
+        call.getTarget() = Builtin::error().getType().getMethod("Error")
+        or
+        call.getTarget().(Method).hasQualifiedName("fmt", "Stringer", "String")
+      )
+    }
 
     override predicate isAdditionalFlowStep(DataFlow::Node src, DataFlow::Node trg) {
       // A taint propagating data-flow edge through structs: a tainted write taints the entire struct.
diff --git a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
index 8196110a435..39d590dec64 100644
--- a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
+++ b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
@@ -1,6 +1,7 @@
 edges
 | klog.go:20:30:20:37 | selection of Header : Header | klog.go:22:15:22:20 | header |
 | klog.go:28:13:28:20 | selection of Header : Header | klog.go:28:13:28:41 | call to Get |
+| overrides.go:9:9:9:16 | password : string | overrides.go:13:14:13:23 | call to String |
 | passwords.go:8:12:8:12 | definition of x : string | passwords.go:9:14:9:14 | x |
 | passwords.go:30:8:30:15 | password : string | passwords.go:8:12:8:12 | definition of x : string |
 | passwords.go:34:28:34:35 | password : string | passwords.go:34:14:34:35 | ...+... |
@@ -30,6 +31,8 @@ nodes
 | klog.go:28:13:28:41 | call to Get | semmle.label | call to Get |
 | main.go:15:14:15:21 | password | semmle.label | password |
 | main.go:17:12:17:19 | password | semmle.label | password |
+| overrides.go:9:9:9:16 | password : string | semmle.label | password : string |
+| overrides.go:13:14:13:23 | call to String | semmle.label | call to String |
 | passwords.go:8:12:8:12 | definition of x : string | semmle.label | definition of x : string |
 | passwords.go:9:14:9:14 | x | semmle.label | x |
 | passwords.go:25:14:25:21 | password | semmle.label | password |
@@ -75,6 +78,7 @@ nodes
 | klog.go:28:13:28:41 | call to Get | klog.go:28:13:28:20 | selection of Header : Header | klog.go:28:13:28:41 | call to Get | Sensitive data returned by $@ is logged here. | klog.go:28:13:28:20 | selection of Header | HTTP request headers |
 | main.go:15:14:15:21 | password | main.go:15:14:15:21 | password | main.go:15:14:15:21 | password | Sensitive data returned by $@ is logged here. | main.go:15:14:15:21 | password | an access to password |
 | main.go:17:12:17:19 | password | main.go:17:12:17:19 | password | main.go:17:12:17:19 | password | Sensitive data returned by $@ is logged here. | main.go:17:12:17:19 | password | an access to password |
+| overrides.go:13:14:13:23 | call to String | overrides.go:9:9:9:16 | password : string | overrides.go:13:14:13:23 | call to String | Sensitive data returned by $@ is logged here. | overrides.go:9:9:9:16 | password | an access to password |
 | passwords.go:9:14:9:14 | x | passwords.go:30:8:30:15 | password : string | passwords.go:9:14:9:14 | x | Sensitive data returned by $@ is logged here. | passwords.go:30:8:30:15 | password | an access to password |
 | passwords.go:25:14:25:21 | password | passwords.go:25:14:25:21 | password | passwords.go:25:14:25:21 | password | Sensitive data returned by $@ is logged here. | passwords.go:25:14:25:21 | password | an access to password |
 | passwords.go:26:14:26:23 | selection of password | passwords.go:26:14:26:23 | selection of password | passwords.go:26:14:26:23 | selection of password | Sensitive data returned by $@ is logged here. | passwords.go:26:14:26:23 | selection of password | an access to password |

From 63187a0889e3c7a1b79373ab7dad5e7e91b7f480 Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 1 Jul 2020 18:27:05 +0100
Subject: [PATCH 08/10] Make clear-text logging sources more precise.

---
 ql/src/semmle/go/security/CleartextLogging.qll |  4 +++-
 .../CleartextLoggingCustomizations.qll         |  8 +++-----
 .../Security/CWE-312/CleartextLogging.expected | 18 +++++++++---------
 .../query-tests/Security/CWE-312/overrides.go  | 15 +++++++++++++++
 4 files changed, 30 insertions(+), 15 deletions(-)
 create mode 100644 ql/test/query-tests/Security/CWE-312/overrides.go

diff --git a/ql/src/semmle/go/security/CleartextLogging.qll b/ql/src/semmle/go/security/CleartextLogging.qll
index 1d864705149..d3e0793afac 100644
--- a/ql/src/semmle/go/security/CleartextLogging.qll
+++ b/ql/src/semmle/go/security/CleartextLogging.qll
@@ -44,7 +44,9 @@ module CleartextLogging {
 
     override predicate isAdditionalFlowStep(DataFlow::Node src, DataFlow::Node trg) {
       // A taint propagating data-flow edge through structs: a tainted write taints the entire struct.
-      exists(Write write | write.writesField(trg.getASuccessor*(), _, src))
+      exists(Write write |
+        write.writesField(trg.(DataFlow::PostUpdateNode).getPreUpdateNode(), _, src)
+      )
       or
       // taint steps that do not include flow through fields
       TaintTracking::localTaintStep(src, trg) and not TaintTracking::fieldReadStep(src, trg)
diff --git a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
index d5137dd4116..62d9438af41 100644
--- a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
+++ b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
@@ -111,7 +111,7 @@ module CleartextLogging {
   abstract private class NonCleartextPassword extends DataFlow::Node { }
 
   /**
-   * An struct with a field that may contain password information.
+   * A value assigned to a struct field that may contain password information.
    *
    * This is a source since `log.Print(obj)` will often show the fields of `obj`.
    */
@@ -119,14 +119,12 @@ module CleartextLogging {
     string name;
 
     StructPasswordFieldSource() {
-      exists(Write write, Field f, DataFlow::Node rhs |
-        write.writesField(this.getASuccessor*(), f, rhs)
-      |
+      exists(Write write, Field f | write.writesField(_, f, this) |
         name = f.getName() and
         name.regexpMatch(maybePassword()) and
         not name.regexpMatch(notSensitive()) and
         // avoid safe values assigned to presumably unsafe names
-        not rhs instanceof NonCleartextPassword
+        not this instanceof NonCleartextPassword
       )
     }
 
diff --git a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
index 39d590dec64..1778719b87d 100644
--- a/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
+++ b/ql/test/query-tests/Security/CWE-312/CleartextLogging.expected
@@ -5,18 +5,18 @@ edges
 | passwords.go:8:12:8:12 | definition of x : string | passwords.go:9:14:9:14 | x |
 | passwords.go:30:8:30:15 | password : string | passwords.go:8:12:8:12 | definition of x : string |
 | passwords.go:34:28:34:35 | password : string | passwords.go:34:14:34:35 | ...+... |
-| passwords.go:36:10:38:2 | struct literal : passStruct | passwords.go:39:14:39:17 | obj1 |
+| passwords.go:37:13:37:13 | x : string | passwords.go:39:14:39:17 | obj1 |
 | passwords.go:42:6:42:13 | password : string | passwords.go:44:14:44:17 | obj2 |
 | passwords.go:48:11:48:18 | password : string | passwords.go:47:14:47:17 | obj3 |
-| passwords.go:85:19:87:2 | struct literal : passSetStruct | passwords.go:88:14:88:26 | utilityObject |
+| passwords.go:86:16:86:36 | call to make : map type | passwords.go:88:14:88:26 | utilityObject |
 | passwords.go:90:12:90:19 | password : string | passwords.go:91:23:91:28 | secret |
 | passwords.go:101:33:101:40 | password : string | passwords.go:101:15:101:40 | ...+... |
 | passwords.go:107:34:107:41 | password : string | passwords.go:107:16:107:41 | ...+... |
 | passwords.go:112:33:112:40 | password : string | passwords.go:112:15:112:40 | ...+... |
 | passwords.go:116:28:116:36 | password1 : stringable | passwords.go:116:14:116:45 | ...+... |
-| passwords.go:118:12:123:2 | struct literal : Config | passwords.go:125:14:125:19 | config |
 | passwords.go:118:12:123:2 | struct literal [x] : string | passwords.go:126:14:126:19 | config [x] : string |
 | passwords.go:118:12:123:2 | struct literal [y] : string | passwords.go:127:14:127:19 | config [y] : string |
+| passwords.go:119:13:119:13 | x : string | passwords.go:125:14:125:19 | config |
 | passwords.go:121:13:121:20 | password : string | passwords.go:118:12:123:2 | struct literal [x] : string |
 | passwords.go:121:13:121:20 | password : string | passwords.go:125:14:125:19 | config |
 | passwords.go:122:13:122:25 | call to getPassword : string | passwords.go:118:12:123:2 | struct literal [y] : string |
@@ -43,14 +43,14 @@ nodes
 | passwords.go:32:12:32:19 | password | semmle.label | password |
 | passwords.go:34:14:34:35 | ...+... | semmle.label | ...+... |
 | passwords.go:34:28:34:35 | password : string | semmle.label | password : string |
-| passwords.go:36:10:38:2 | struct literal : passStruct | semmle.label | struct literal : passStruct |
+| passwords.go:37:13:37:13 | x : string | semmle.label | x : string |
 | passwords.go:39:14:39:17 | obj1 | semmle.label | obj1 |
 | passwords.go:42:6:42:13 | password : string | semmle.label | password : string |
 | passwords.go:44:14:44:17 | obj2 | semmle.label | obj2 |
 | passwords.go:47:14:47:17 | obj3 | semmle.label | obj3 |
 | passwords.go:48:11:48:18 | password : string | semmle.label | password : string |
 | passwords.go:51:14:51:27 | fixed_password | semmle.label | fixed_password |
-| passwords.go:85:19:87:2 | struct literal : passSetStruct | semmle.label | struct literal : passSetStruct |
+| passwords.go:86:16:86:36 | call to make : map type | semmle.label | call to make : map type |
 | passwords.go:88:14:88:26 | utilityObject | semmle.label | utilityObject |
 | passwords.go:90:12:90:19 | password : string | semmle.label | password : string |
 | passwords.go:91:23:91:28 | secret | semmle.label | secret |
@@ -62,9 +62,9 @@ nodes
 | passwords.go:112:33:112:40 | password : string | semmle.label | password : string |
 | passwords.go:116:14:116:45 | ...+... | semmle.label | ...+... |
 | passwords.go:116:28:116:36 | password1 : stringable | semmle.label | password1 : stringable |
-| passwords.go:118:12:123:2 | struct literal : Config | semmle.label | struct literal : Config |
 | passwords.go:118:12:123:2 | struct literal [x] : string | semmle.label | struct literal [x] : string |
 | passwords.go:118:12:123:2 | struct literal [y] : string | semmle.label | struct literal [y] : string |
+| passwords.go:119:13:119:13 | x : string | semmle.label | x : string |
 | passwords.go:121:13:121:20 | password : string | semmle.label | password : string |
 | passwords.go:122:13:122:25 | call to getPassword : string | semmle.label | call to getPassword : string |
 | passwords.go:125:14:125:19 | config | semmle.label | config |
@@ -87,17 +87,17 @@ nodes
 | passwords.go:28:14:28:28 | call to getPassword | util.go:16:9:16:18 | selection of password : string | passwords.go:28:14:28:28 | call to getPassword | Sensitive data returned by $@ is logged here. | util.go:16:9:16:18 | selection of password | an access to password |
 | passwords.go:32:12:32:19 | password | passwords.go:32:12:32:19 | password | passwords.go:32:12:32:19 | password | Sensitive data returned by $@ is logged here. | passwords.go:32:12:32:19 | password | an access to password |
 | passwords.go:34:14:34:35 | ...+... | passwords.go:34:28:34:35 | password : string | passwords.go:34:14:34:35 | ...+... | Sensitive data returned by $@ is logged here. | passwords.go:34:28:34:35 | password | an access to password |
-| passwords.go:39:14:39:17 | obj1 | passwords.go:36:10:38:2 | struct literal : passStruct | passwords.go:39:14:39:17 | obj1 | Sensitive data returned by $@ is logged here. | passwords.go:36:10:38:2 | struct literal | an access to password |
+| passwords.go:39:14:39:17 | obj1 | passwords.go:37:13:37:13 | x : string | passwords.go:39:14:39:17 | obj1 | Sensitive data returned by $@ is logged here. | passwords.go:37:13:37:13 | x | an access to password |
 | passwords.go:44:14:44:17 | obj2 | passwords.go:42:6:42:13 | password : string | passwords.go:44:14:44:17 | obj2 | Sensitive data returned by $@ is logged here. | passwords.go:42:6:42:13 | password | an access to password |
 | passwords.go:47:14:47:17 | obj3 | passwords.go:48:11:48:18 | password : string | passwords.go:47:14:47:17 | obj3 | Sensitive data returned by $@ is logged here. | passwords.go:48:11:48:18 | password | an access to password |
 | passwords.go:51:14:51:27 | fixed_password | passwords.go:51:14:51:27 | fixed_password | passwords.go:51:14:51:27 | fixed_password | Sensitive data returned by $@ is logged here. | passwords.go:51:14:51:27 | fixed_password | an access to fixed_password |
-| passwords.go:88:14:88:26 | utilityObject | passwords.go:85:19:87:2 | struct literal : passSetStruct | passwords.go:88:14:88:26 | utilityObject | Sensitive data returned by $@ is logged here. | passwords.go:85:19:87:2 | struct literal | an access to passwordSet |
+| passwords.go:88:14:88:26 | utilityObject | passwords.go:86:16:86:36 | call to make : map type | passwords.go:88:14:88:26 | utilityObject | Sensitive data returned by $@ is logged here. | passwords.go:86:16:86:36 | call to make | an access to passwordSet |
 | passwords.go:91:23:91:28 | secret | passwords.go:90:12:90:19 | password : string | passwords.go:91:23:91:28 | secret | Sensitive data returned by $@ is logged here. | passwords.go:90:12:90:19 | password | an access to password |
 | passwords.go:101:15:101:40 | ...+... | passwords.go:101:33:101:40 | password : string | passwords.go:101:15:101:40 | ...+... | Sensitive data returned by $@ is logged here. | passwords.go:101:33:101:40 | password | an access to password |
 | passwords.go:107:16:107:41 | ...+... | passwords.go:107:34:107:41 | password : string | passwords.go:107:16:107:41 | ...+... | Sensitive data returned by $@ is logged here. | passwords.go:107:34:107:41 | password | an access to password |
 | passwords.go:112:15:112:40 | ...+... | passwords.go:112:33:112:40 | password : string | passwords.go:112:15:112:40 | ...+... | Sensitive data returned by $@ is logged here. | passwords.go:112:33:112:40 | password | an access to password |
 | passwords.go:116:14:116:45 | ...+... | passwords.go:116:28:116:36 | password1 : stringable | passwords.go:116:14:116:45 | ...+... | Sensitive data returned by $@ is logged here. | passwords.go:116:28:116:36 | password1 | an access to password1 |
-| passwords.go:125:14:125:19 | config | passwords.go:118:12:123:2 | struct literal : Config | passwords.go:125:14:125:19 | config | Sensitive data returned by $@ is logged here. | passwords.go:118:12:123:2 | struct literal | an access to password |
+| passwords.go:125:14:125:19 | config | passwords.go:119:13:119:13 | x : string | passwords.go:125:14:125:19 | config | Sensitive data returned by $@ is logged here. | passwords.go:119:13:119:13 | x | an access to password |
 | passwords.go:125:14:125:19 | config | passwords.go:121:13:121:20 | password : string | passwords.go:125:14:125:19 | config | Sensitive data returned by $@ is logged here. | passwords.go:121:13:121:20 | password | an access to password |
 | passwords.go:125:14:125:19 | config | passwords.go:122:13:122:25 | call to getPassword : string | passwords.go:125:14:125:19 | config | Sensitive data returned by $@ is logged here. | passwords.go:122:13:122:25 | call to getPassword | a call to getPassword |
 | passwords.go:126:14:126:21 | selection of x | passwords.go:121:13:121:20 | password : string | passwords.go:126:14:126:21 | selection of x | Sensitive data returned by $@ is logged here. | passwords.go:121:13:121:20 | password | an access to password |
diff --git a/ql/test/query-tests/Security/CWE-312/overrides.go b/ql/test/query-tests/Security/CWE-312/overrides.go
new file mode 100644
index 00000000000..7828898f312
--- /dev/null
+++ b/ql/test/query-tests/Security/CWE-312/overrides.go
@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+type s struct {}
+
+func (_ s) String() string {
+	password := "horsebatterystaplecorrect"
+	return password
+}
+
+func overrideTest(x s, y fmt.Stringer) {
+	fmt.Println(x.String()) // NOT OK
+	fmt.Println(y.String()) // OK
+}
\ No newline at end of file

From 89e9c6c2da769bfda3676c6608b9dd87f3b29cf3 Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 1 Jul 2020 18:27:44 +0100
Subject: [PATCH 09/10] Teach clear-text logging query to ignore dummy
 passwords.

---
 .../go/security/CleartextLoggingCustomizations.qll       | 4 ++++
 ql/test/query-tests/Security/CWE-312/passwords.go        | 9 +++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
index 62d9438af41..329b4e67854 100644
--- a/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
+++ b/ql/src/semmle/go/security/CleartextLoggingCustomizations.qll
@@ -6,6 +6,7 @@
 
 import go
 private import semmle.go.security.SensitiveActions::HeuristicNames
+private import semmle.go.security.SensitiveActions::PasswordHeuristics
 
 /**
  * Provides extension points for customizing the data-flow tracking configuration for reasoning
@@ -67,6 +68,9 @@ module CleartextLogging {
           .(Ident)
           .getName()
           .regexpMatch("(?is).*(messages|strings).*")
+      or
+      // avoid dummy passwords
+      isDummyPassword(this.getStringValue())
     }
   }
 
diff --git a/ql/test/query-tests/Security/CWE-312/passwords.go b/ql/test/query-tests/Security/CWE-312/passwords.go
index 777fceb9374..5f0b291016d 100644
--- a/ql/test/query-tests/Security/CWE-312/passwords.go
+++ b/ql/test/query-tests/Security/CWE-312/passwords.go
@@ -19,7 +19,7 @@ func redact(kind, value string) string {
 func test() {
 	name := "user"
 	password := "P@ssw0rd"
-	x := "aaaaa"
+	x := "horsebatterystapleincorrect"
 	var o passStruct
 
 	log.Println(password)        // NOT OK
@@ -47,7 +47,7 @@ func test() {
 	log.Println(obj3) // caught because of the below line
 	obj3.x = password // NOT OK
 
-	fixed_password := "123"
+	fixed_password := "cowbatterystaplecorrect"
 	log.Println(fixed_password) // Probably OK, but caught
 
 	log.Println(IncorrectPasswordError) // OK
@@ -125,6 +125,11 @@ func test() {
 	log.Println(config)          // NOT OK
 	log.Println(config.x)        // NOT OK
 	log.Println(config.y)        // NOT OK
+
+	obj4 := xStruct{
+		x: "aaaaa",
+	}
+	log.Println(obj4) // OK
 }
 
 const password = "horsebatterystaplecorrect"

From b83076853f183d982a037d860671c51d3c93dafa Mon Sep 17 00:00:00 2001
From: Max Schaefer <max-schaefer@github.com>
Date: Wed, 24 Jun 2020 07:45:33 +0100
Subject: [PATCH 10/10] Add change note.

---
 change-notes/2020-06-24-clear-text-logging.md | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 change-notes/2020-06-24-clear-text-logging.md

diff --git a/change-notes/2020-06-24-clear-text-logging.md b/change-notes/2020-06-24-clear-text-logging.md
new file mode 100644
index 00000000000..6dd26dbb1ee
--- /dev/null
+++ b/change-notes/2020-06-24-clear-text-logging.md
@@ -0,0 +1,2 @@
+lgtm,codescanning
+* The query "Clear-text logging of sensitive information" has been improved to recognize more sources of sensitive data, which may lead to more alerts. The query is now also more precise, which may reduce the number of false positives.