From 20374d1d759bc4e17486bde1cb9dca5be37d9e52 Mon Sep 17 00:00:00 2001 From: Roland Shoemaker Date: Mon, 20 Mar 2023 11:01:13 -0700 Subject: [PATCH] [release-branch.go1.20] html/template: disallow actions in JS template literals ECMAScript 6 introduced template literals[0][1] which are delimited with backticks. These need to be escaped in a similar fashion to the delimiters for other string literals. Additionally template literals can contain special syntax for string interpolation. There is no clear way to allow safe insertion of actions within JS template literals, as handling (JS) string interpolation inside of these literals is rather complex. As such we've chosen to simply disallow template actions within these template literals. A new error code is added for this parsing failure case, errJsTmplLit, but it is unexported as it is not backwards compatible with other minor release versions to introduce an API change in a minor release. We will export this code in the next major release. The previous behavior (with the cavet that backticks are now escaped properly) can be re-enabled with GODEBUG=jstmpllitinterp=1. This change subsumes CL471455. Thanks to Sohom Datta, Manipal Institute of Technology, for reporting this issue. Fixes CVE-2023-24538 For #59234 Fixes #59272 [0] https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-template-literals [1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals Change-Id: Idff74ec386e9b73d6e9a3c9f71990eabc0ce7506 Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1802457 Reviewed-by: Damien Neil Run-TryBot: Damien Neil Reviewed-by: Julie Qiu Reviewed-by: Roland Shoemaker Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1802688 Run-TryBot: Roland Shoemaker Reviewed-on: https://go-review.googlesource.com/c/go/+/481993 Run-TryBot: Michael Knyszek Auto-Submit: Michael Knyszek TryBot-Bypass: Michael Knyszek Reviewed-by: Matthew Dempsky --- src/html/template/context.go | 2 + src/html/template/error.go | 13 ++++++ src/html/template/escape.go | 12 ++++++ src/html/template/escape_test.go | 66 +++++++++++++++++-------------- src/html/template/js.go | 2 + src/html/template/js_test.go | 2 +- src/html/template/jsctx_string.go | 9 +++++ src/html/template/state_string.go | 37 ++++++++++++++++- src/html/template/transition.go | 7 +++- 9 files changed, 117 insertions(+), 33 deletions(-) diff --git a/src/html/template/context.go b/src/html/template/context.go index a97c8be56f..c28fb0c5ea 100644 --- a/src/html/template/context.go +++ b/src/html/template/context.go @@ -120,6 +120,8 @@ const ( stateJSDqStr // stateJSSqStr occurs inside a JavaScript single quoted string. stateJSSqStr + // stateJSBqStr occurs inside a JavaScript back quoted string. + stateJSBqStr // stateJSRegexp occurs inside a JavaScript regexp literal. stateJSRegexp // stateJSBlockCmt occurs inside a JavaScript /* block comment */. diff --git a/src/html/template/error.go b/src/html/template/error.go index 5c51f772cb..d7d6f5b3ab 100644 --- a/src/html/template/error.go +++ b/src/html/template/error.go @@ -214,6 +214,19 @@ const ( // pipeline occurs in an unquoted attribute value context, "html" is // disallowed. Avoid using "html" and "urlquery" entirely in new templates. ErrPredefinedEscaper + + // errJSTmplLit: "... appears in a JS template literal" + // Example: + // + // Discussion: + // Package html/template does not support actions inside of JS template + // literals. + // + // TODO(rolandshoemaker): we cannot add this as an exported error in a minor + // release, since it is backwards incompatible with the other minor + // releases. As such we need to leave it unexported, and then we'll add it + // in the next major release. + errJSTmplLit ) func (e *Error) Error() string { diff --git a/src/html/template/escape.go b/src/html/template/escape.go index 54fbcdca33..23ece7a72f 100644 --- a/src/html/template/escape.go +++ b/src/html/template/escape.go @@ -8,6 +8,7 @@ import ( "bytes" "fmt" "html" + "internal/godebug" "io" "text/template" "text/template/parse" @@ -160,6 +161,8 @@ func (e *escaper) escape(c context, n parse.Node) context { panic("escaping " + n.String() + " is unimplemented") } +var debugAllowActionJSTmpl = godebug.New("jstmpllitinterp") + // escapeAction escapes an action template node. func (e *escaper) escapeAction(c context, n *parse.ActionNode) context { if len(n.Pipe.Decl) != 0 { @@ -223,6 +226,15 @@ func (e *escaper) escapeAction(c context, n *parse.ActionNode) context { c.jsCtx = jsCtxDivOp case stateJSDqStr, stateJSSqStr: s = append(s, "_html_template_jsstrescaper") + case stateJSBqStr: + if debugAllowActionJSTmpl.Value() == "1" { + s = append(s, "_html_template_jsstrescaper") + } else { + return context{ + state: stateError, + err: errorf(errJSTmplLit, n, n.Line, "%s appears in a JS template literal", n), + } + } case stateJSRegexp: s = append(s, "_html_template_jsregexpescaper") case stateCSS: diff --git a/src/html/template/escape_test.go b/src/html/template/escape_test.go index 12add077c3..3dd212bac9 100644 --- a/src/html/template/escape_test.go +++ b/src/html/template/escape_test.go @@ -681,35 +681,31 @@ func TestEscape(t *testing.T) { } for _, test := range tests { - tmpl := New(test.name) - tmpl = Must(tmpl.Parse(test.input)) - // Check for bug 6459: Tree field was not set in Parse. - if tmpl.Tree != tmpl.text.Tree { - t.Errorf("%s: tree not set properly", test.name) - continue - } - b := new(strings.Builder) - if err := tmpl.Execute(b, data); err != nil { - t.Errorf("%s: template execution failed: %s", test.name, err) - continue - } - if w, g := test.output, b.String(); w != g { - t.Errorf("%s: escaped output: want\n\t%q\ngot\n\t%q", test.name, w, g) - continue - } - b.Reset() - if err := tmpl.Execute(b, pdata); err != nil { - t.Errorf("%s: template execution failed for pointer: %s", test.name, err) - continue - } - if w, g := test.output, b.String(); w != g { - t.Errorf("%s: escaped output for pointer: want\n\t%q\ngot\n\t%q", test.name, w, g) - continue - } - if tmpl.Tree != tmpl.text.Tree { - t.Errorf("%s: tree mismatch", test.name) - continue - } + t.Run(test.name, func(t *testing.T) { + tmpl := New(test.name) + tmpl = Must(tmpl.Parse(test.input)) + // Check for bug 6459: Tree field was not set in Parse. + if tmpl.Tree != tmpl.text.Tree { + t.Fatalf("%s: tree not set properly", test.name) + } + b := new(strings.Builder) + if err := tmpl.Execute(b, data); err != nil { + t.Fatalf("%s: template execution failed: %s", test.name, err) + } + if w, g := test.output, b.String(); w != g { + t.Fatalf("%s: escaped output: want\n\t%q\ngot\n\t%q", test.name, w, g) + } + b.Reset() + if err := tmpl.Execute(b, pdata); err != nil { + t.Fatalf("%s: template execution failed for pointer: %s", test.name, err) + } + if w, g := test.output, b.String(); w != g { + t.Fatalf("%s: escaped output for pointer: want\n\t%q\ngot\n\t%q", test.name, w, g) + } + if tmpl.Tree != tmpl.text.Tree { + t.Fatalf("%s: tree mismatch", test.name) + } + }) } } @@ -936,6 +932,10 @@ func TestErrors(t *testing.T) { "{{range .Items}}{{if .X}}{{break}}{{end}}{{end}}", "", }, + { + "`", + "", + }, // Error cases. { "{{if .Cond}}var tmpl = `asd {{.}}`;", + `{{.}} appears in a JS template literal`, + }, } for _, test := range tests { buf := new(bytes.Buffer) @@ -1303,6 +1307,10 @@ func TestEscapeText(t *testing.T) { `= state(len(_state_index)-1) { diff --git a/src/html/template/transition.go b/src/html/template/transition.go index 06df679330..92eb351906 100644 --- a/src/html/template/transition.go +++ b/src/html/template/transition.go @@ -27,6 +27,7 @@ var transitionFunc = [...]func(context, []byte) (context, int){ stateJS: tJS, stateJSDqStr: tJSDelimited, stateJSSqStr: tJSDelimited, + stateJSBqStr: tJSDelimited, stateJSRegexp: tJSDelimited, stateJSBlockCmt: tBlockCmt, stateJSLineCmt: tLineCmt, @@ -262,7 +263,7 @@ func tURL(c context, s []byte) (context, int) { // tJS is the context transition function for the JS state. func tJS(c context, s []byte) (context, int) { - i := bytes.IndexAny(s, `"'/`) + i := bytes.IndexAny(s, "\"`'/") if i == -1 { // Entire input is non string, comment, regexp tokens. c.jsCtx = nextJSCtx(s, c.jsCtx) @@ -274,6 +275,8 @@ func tJS(c context, s []byte) (context, int) { c.state, c.jsCtx = stateJSDqStr, jsCtxRegexp case '\'': c.state, c.jsCtx = stateJSSqStr, jsCtxRegexp + case '`': + c.state, c.jsCtx = stateJSBqStr, jsCtxRegexp case '/': switch { case i+1 < len(s) && s[i+1] == '/': @@ -303,6 +306,8 @@ func tJSDelimited(c context, s []byte) (context, int) { switch c.state { case stateJSSqStr: specials = `\'` + case stateJSBqStr: + specials = "`\\" case stateJSRegexp: specials = `\/[]` } -- 2.48.1