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html/template: support parsing complex JS template literals

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This change undoes the restrictions added in CL 482079, which added a
blanket ban on using actions within JS template literal strings, and
adds logic to support actions while properly applies contextual escaping
based on the correct context within the literal.

Since template literals can contain both normal strings, and nested JS
contexts, logic is required to properly track those context switches
during parsing.

ErrJsTmplLit is deprecated, and the GODEBUG flag jstmpllitinterp no
longer does anything.

Fixes #61619

Change-Id: I0338cc6f663723267b8f7aaacc55aa28f60906f2
Reviewed-on: https://go-review.googlesource.com/c/go/+/507995
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Roland Shoemaker <roland@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
This commit is contained in:
Roland Shoemaker 2023-07-05 11:56:03 -07:00 committed by Gopher Robot
parent deb8e29000
commit c9c885f92f
8 changed files with 253 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
api/next/61619.txt Normal file
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@ -0,0 +1 @@
pkg html/template, const ErrJSTemplate //deprecated #61619

24
src/html/template/context.go
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@ -17,14 +17,16 @@ import (
// https://www.w3.org/TR/html5/syntax.html#the-end
// where the context element is null.
type context struct {
state state
delim delim
urlPart urlPart
jsCtx jsCtx
attr attr
element element
n parse.Node // for range break/continue
err *Error
state state
delim delim
urlPart urlPart
jsCtx jsCtx
jsTmplExprDepth int
jsBraceDepth int
attr attr
element element
n parse.Node // for range break/continue
err *Error
}
func (c context) String() string {
@ -120,8 +122,8 @@ const (
stateJSDqStr
// stateJSSqStr occurs inside a JavaScript single quoted string.
stateJSSqStr
// stateJSBqStr occurs inside a JavaScript back quoted string.
stateJSBqStr
// stateJSTmplLit occurs inside a JavaScript back quoted string.
stateJSTmplLit
// stateJSRegexp occurs inside a JavaScript regexp literal.
stateJSRegexp
// stateJSBlockCmt occurs inside a JavaScript /* block comment */.
@ -182,7 +184,7 @@ func isInScriptLiteral(s state) bool {
// stateJSHTMLOpenCmt, stateJSHTMLCloseCmt) because their content is already
// omitted from the output.
switch s {
case stateJSDqStr, stateJSSqStr, stateJSBqStr, stateJSRegexp:
case stateJSDqStr, stateJSSqStr, stateJSTmplLit, stateJSRegexp:
return true
}
return false

4
src/html/template/error.go
View File

@ -221,6 +221,10 @@ const (
// Discussion:
// Package html/template does not support actions inside of JS template
// literals.
//
// Deprecated: ErrJSTemplate is no longer returned when an action is present
// in a JS template literal. Actions inside of JS template literals are now
// escaped as expected.
ErrJSTemplate
)

48
src/html/template/escape.go
View File

@ -62,22 +62,23 @@ func evalArgs(args ...any) string {
// funcMap maps command names to functions that render their inputs safe.
var funcMap = template.FuncMap{
"_html_template_attrescaper": attrEscaper,
"_html_template_commentescaper": commentEscaper,
"_html_template_cssescaper": cssEscaper,
"_html_template_cssvaluefilter": cssValueFilter,
"_html_template_htmlnamefilter": htmlNameFilter,
"_html_template_htmlescaper": htmlEscaper,
"_html_template_jsregexpescaper": jsRegexpEscaper,
"_html_template_jsstrescaper": jsStrEscaper,
"_html_template_jsvalescaper": jsValEscaper,
"_html_template_nospaceescaper": htmlNospaceEscaper,
"_html_template_rcdataescaper": rcdataEscaper,
"_html_template_srcsetescaper": srcsetFilterAndEscaper,
"_html_template_urlescaper": urlEscaper,
"_html_template_urlfilter": urlFilter,
"_html_template_urlnormalizer": urlNormalizer,
"_eval_args_": evalArgs,
"_html_template_attrescaper": attrEscaper,
"_html_template_commentescaper": commentEscaper,
"_html_template_cssescaper": cssEscaper,
"_html_template_cssvaluefilter": cssValueFilter,
"_html_template_htmlnamefilter": htmlNameFilter,
"_html_template_htmlescaper": htmlEscaper,
"_html_template_jsregexpescaper": jsRegexpEscaper,
"_html_template_jsstrescaper": jsStrEscaper,
"_html_template_jstmpllitescaper": jsTmplLitEscaper,
"_html_template_jsvalescaper": jsValEscaper,
"_html_template_nospaceescaper": htmlNospaceEscaper,
"_html_template_rcdataescaper": rcdataEscaper,
"_html_template_srcsetescaper": srcsetFilterAndEscaper,
"_html_template_urlescaper": urlEscaper,
"_html_template_urlfilter": urlFilter,
"_html_template_urlnormalizer": urlNormalizer,
"_eval_args_": evalArgs,
}
// escaper collects type inferences about templates and changes needed to make
@ -227,16 +228,8 @@ 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" {
debugAllowActionJSTmpl.IncNonDefault()
s = append(s, "_html_template_jsstrescaper")
} else {
return context{
state: stateError,
err: errorf(ErrJSTemplate, n, n.Line, "%s appears in a JS template literal", n),
}
}
case stateJSTmplLit:
s = append(s, "_html_template_jstmpllitescaper")
case stateJSRegexp:
s = append(s, "_html_template_jsregexpescaper")
case stateCSS:
@ -395,6 +388,9 @@ var redundantFuncs = map[string]map[string]bool{
"_html_template_jsstrescaper": {
"_html_template_attrescaper": true,
},
"_html_template_jstmpllitescaper": {
"_html_template_attrescaper": true,
},
"_html_template_urlescaper": {
"_html_template_urlnormalizer": true,
},

135
src/html/template/escape_test.go
View File

@ -30,14 +30,14 @@ func (x *goodMarshaler) MarshalJSON() ([]byte, error) {
func TestEscape(t *testing.T) {
data := struct {
F, T bool
C, G, H string
A, E []string
B, M json.Marshaler
N int
U any // untyped nil
Z *int // typed nil
W HTML
F, T bool
C, G, H, I string
A, E []string
B, M json.Marshaler
N int
U any // untyped nil
Z *int // typed nil
W HTML
}{
F: false,
T: true,
@ -52,6 +52,7 @@ func TestEscape(t *testing.T) {
U: nil,
Z: nil,
W: HTML(`&iexcl;<b class="foo">Hello</b>, <textarea>O'World</textarea>!`),
I: "${ asd `` }",
}
pdata := &data
@ -718,6 +719,21 @@ func TestEscape(t *testing.T) {
"<p name=\"{{.U}}\">",
"<p name=\"\">",
},
{
"JS template lit special characters",
"<script>var a = `{{.I}}`</script>",
"<script>var a = `\\u0024\\u007b asd \\u0060\\u0060 \\u007d`</script>",
},
{
"JS template lit special characters, nested lit",
"<script>var a = `${ `{{.I}}` }`</script>",
"<script>var a = `${ `\\u0024\\u007b asd \\u0060\\u0060 \\u007d` }`</script>",
},
{
"JS template lit, nested JS",
"<script>var a = `${ var a = \"{{\"a \\\" d\"}}\" }`</script>",
"<script>var a = `${ var a = \"a \\u0022 d\" }`</script>",
},
}
for _, test := range tests {
@ -976,6 +992,31 @@ func TestErrors(t *testing.T) {
"<script>var a = `${a+b}`</script>`",
"",
},
{
"<script>var tmpl = `asd`;</script>",
``,
},
{
"<script>var tmpl = `${1}`;</script>",
``,
},
{
"<script>var tmpl = `${return ``}`;</script>",
``,
},
{
"<script>var tmpl = `${return {{.}} }`;</script>",
``,
},
{
"<script>var tmpl = `${ let a = {1:1} {{.}} }`;</script>",
``,
},
{
"<script>var tmpl = `asd ${return \"{\"}`;</script>",
``,
},
// Error cases.
{
"{{if .Cond}}<a{{end}}",
@ -1122,10 +1163,26 @@ func TestErrors(t *testing.T) {
// html is allowed since it is the last command in the pipeline, but urlquery is not.
`predefined escaper "urlquery" disallowed in template`,
},
{
"<script>var tmpl = `asd {{.}}`;</script>",
`{{.}} appears in a JS template literal`,
},
// {
// "<script>var tmpl = `asd {{.}}`;</script>",
// `{{.}} appears in a JS template literal`,
// },
// {
// "<script>var v = `${function(){return `{{.V}}+1`}()}`;</script>",
// `{{.V}} appears in a JS template literal`,
// },
// {
// "<script>var a = `asd ${function(){b = {1:2}; return`{{.}}`}}`</script>",
// `{{.}} appears in a JS template literal`,
// },
// {
// "<script>var tmpl = `${return `{{.}}`}`;</script>",
// `{{.}} appears in a JS template literal`,
// },
// {
// "<script>var tmpl = `${return {`{{.}}`}`;</script>",
// `{{.}} appears in a JS template literal`,
// },
}
for _, test := range tests {
buf := new(bytes.Buffer)
@ -1349,7 +1406,7 @@ func TestEscapeText(t *testing.T) {
},
{
"<a onclick=\"`foo",
context{state: stateJSBqStr, delim: delimDoubleQuote, attr: attrScript},
context{state: stateJSTmplLit, delim: delimDoubleQuote, attr: attrScript},
},
{
`<A ONCLICK="'`,
@ -1691,6 +1748,58 @@ func TestEscapeText(t *testing.T) {
`<svg:a svg:onclick="x()">`,
context{},
},
{
"<script>var a = `",
context{state: stateJSTmplLit, element: elementScript},
},
{
"<script>var a = `${",
context{state: stateJS, element: elementScript},
},
{
"<script>var a = `${}",
context{state: stateJSTmplLit, element: elementScript},
},
{
"<script>var a = `${`",
context{state: stateJSTmplLit, element: elementScript},
},
{
"<script>var a = `${var a = \"",
context{state: stateJSDqStr, element: elementScript},
},
{
"<script>var a = `${var a = \"`",
context{state: stateJSDqStr, element: elementScript},
},
{
"<script>var a = `${var a = \"}",
context{state: stateJSDqStr, element: elementScript},
},
{
"<script>var a = `${``",
context{state: stateJS, element: elementScript},
},
{
"<script>var a = `${`}",
context{state: stateJSTmplLit, element: elementScript},
},
{
"<script>`${ {} } asd`</script><script>`${ {} }",
context{state: stateJSTmplLit, element: elementScript},
},
{
"<script>var foo = `${ (_ => { return \"x\" })() + \"${",
context{state: stateJSDqStr, element: elementScript},
},
{
"<script>var a = `${ {</script><script>var b = `${ x }",
context{state: stateJSTmplLit, element: elementScript, jsCtx: jsCtxDivOp},
},
{
"<script>var foo = `x` + \"${",
context{state: stateJSDqStr, element: elementScript},
},
}
for _, test := range tests {

30
src/html/template/js.go
View File

@ -238,6 +238,11 @@ func jsStrEscaper(args ...any) string {
return replace(s, jsStrReplacementTable)
}
func jsTmplLitEscaper(args ...any) string {
s, _ := stringify(args...)
return replace(s, jsBqStrReplacementTable)
}
// jsRegexpEscaper behaves like jsStrEscaper but escapes regular expression
// specials so the result is treated literally when included in a regular
// expression literal. /foo{{.X}}bar/ matches the string "foo" followed by
@ -324,6 +329,31 @@ var jsStrReplacementTable = []string{
'\\': `\\`,
}
// jsBqStrReplacementTable is like jsStrReplacementTable except it also contains
// the special characters for JS template literals: $, {, and }.
var jsBqStrReplacementTable = []string{
0: `\u0000`,
'\t': `\t`,
'\n': `\n`,
'\v': `\u000b`, // "\v" == "v" on IE 6.
'\f': `\f`,
'\r': `\r`,
// Encode HTML specials as hex so the output can be embedded
// in HTML attributes without further encoding.
'"': `\u0022`,
'`': `\u0060`,
'&': `\u0026`,
'\'': `\u0027`,
'+': `\u002b`,
'/': `\/`,
'<': `\u003c`,
'>': `\u003e`,
'\\': `\\`,
'$': `\u0024`,
'{': `\u007b`,
'}': `\u007d`,
}
// jsStrNormReplacementTable is like jsStrReplacementTable but does not
// overencode existing escapes since this table has no entry for `\`.
var jsStrNormReplacementTable = []string{

6
src/html/template/state_string.go
View File

@ -21,7 +21,7 @@ func _() {
_ = x[stateJS-10]
_ = x[stateJSDqStr-11]
_ = x[stateJSSqStr-12]
_ = x[stateJSBqStr-13]
_ = x[stateJSTmplLit-13]
_ = x[stateJSRegexp-14]
_ = x[stateJSBlockCmt-15]
_ = x[stateJSLineCmt-16]
@ -39,9 +39,9 @@ func _() {
_ = x[stateDead-28]
}
const _state_name = "stateTextstateTagstateAttrNamestateAfterNamestateBeforeValuestateHTMLCmtstateRCDATAstateAttrstateURLstateSrcsetstateJSstateJSDqStrstateJSSqStrstateJSBqStrstateJSRegexpstateJSBlockCmtstateJSLineCmtstateJSHTMLOpenCmtstateJSHTMLCloseCmtstateCSSstateCSSDqStrstateCSSSqStrstateCSSDqURLstateCSSSqURLstateCSSURLstateCSSBlockCmtstateCSSLineCmtstateErrorstateDead"
const _state_name = "stateTextstateTagstateAttrNamestateAfterNamestateBeforeValuestateHTMLCmtstateRCDATAstateAttrstateURLstateSrcsetstateJSstateJSDqStrstateJSSqStrstateJSTmplLitstateJSRegexpstateJSBlockCmtstateJSLineCmtstateJSHTMLOpenCmtstateJSHTMLCloseCmtstateCSSstateCSSDqStrstateCSSSqStrstateCSSDqURLstateCSSSqURLstateCSSURLstateCSSBlockCmtstateCSSLineCmtstateErrorstateDead"
var _state_index = [...]uint16{0, 9, 17, 30, 44, 60, 72, 83, 92, 100, 111, 118, 130, 142, 154, 167, 182, 196, 214, 233, 241, 254, 267, 280, 293, 304, 320, 335, 345, 354}
var _state_index = [...]uint16{0, 9, 17, 30, 44, 60, 72, 83, 92, 100, 111, 118, 130, 142, 156, 169, 184, 198, 216, 235, 243, 256, 269, 282, 295, 306, 322, 337, 347, 356}
func (i state) String() string {
if i >= state(len(_state_index)-1) {

63
src/html/template/transition.go
View File

@ -27,8 +27,8 @@ var transitionFunc = [...]func(context, []byte) (context, int){
stateJS: tJS,
stateJSDqStr: tJSDelimited,
stateJSSqStr: tJSDelimited,
stateJSBqStr: tJSDelimited,
stateJSRegexp: tJSDelimited,
stateJSTmplLit: tJSTmpl,
stateJSBlockCmt: tBlockCmt,
stateJSLineCmt: tLineCmt,
stateJSHTMLOpenCmt: tLineCmt,
@ -270,7 +270,7 @@ 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)
@ -283,7 +283,7 @@ func tJS(c context, s []byte) (context, int) {
case '\'':
c.state, c.jsCtx = stateJSSqStr, jsCtxRegexp
case '`':
c.state, c.jsCtx = stateJSBqStr, jsCtxRegexp
c.state, c.jsCtx = stateJSTmplLit, jsCtxRegexp
case '/':
switch {
case i+1 < len(s) && s[i+1] == '/':
@ -320,12 +320,67 @@ func tJS(c context, s []byte) (context, int) {
if i+1 < len(s) && s[i+1] == '!' {
c.state, i = stateJSLineCmt, i+1
}
case '{':
c.jsBraceDepth++
case '}':
if c.jsTmplExprDepth == 0 {
return c, i + 1
}
for j := 0; j <= i; j++ {
switch s[j] {
case '\\':
j++
case '{':
c.jsBraceDepth++
case '}':
c.jsBraceDepth--
}
}
if c.jsBraceDepth >= 0 {
return c, i + 1
}
c.jsTmplExprDepth--
c.jsBraceDepth = 0
c.state = stateJSTmplLit
default:
panic("unreachable")
}
return c, i + 1
}
func tJSTmpl(c context, s []byte) (context, int) {
var k int
for {
i := k + bytes.IndexAny(s[k:], "`\\$")
if i < k {
break
}
switch s[i] {
case '\\':
i++
if i == len(s) {
return context{
state: stateError,
err: errorf(ErrPartialEscape, nil, 0, "unfinished escape sequence in JS string: %q", s),
}, len(s)
}
case '$':
if len(s) >= i+2 && s[i+1] == '{' {
c.jsTmplExprDepth++
c.state = stateJS
return c, i + 2
}
case '`':
// end
c.state = stateJS
return c, i + 1
}
k = i + 1
}
return c, len(s)
}
// tJSDelimited is the context transition function for the JS string and regexp
// states.
func tJSDelimited(c context, s []byte) (context, int) {
@ -333,8 +388,6 @@ func tJSDelimited(c context, s []byte) (context, int) {
switch c.state {
case stateJSSqStr:
specials = `\'`
case stateJSBqStr:
specials = "`\\"
case stateJSRegexp:
specials = `\/[]`
}