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Allow render HTML with css/js external links (#19017)

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* Allow render HTML with css/js external links

* Fix bug because of filename escape chars

* Fix lint

* Update docs about new configuration item

* Fix bug of render HTML in sub directory

* Add CSP head for displaying iframe in rendering file

* Fix test

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* Some improvements

* some improvement

* revert change in SanitizerDisabled of external renderer

* Add sandbox for iframe and support allow-scripts and allow-same-origin

* refactor

* fix

* fix lint

* fine tune

* use single option RENDER_CONTENT_MODE, use sandbox=allow-scripts

* fine tune CSP

* Apply suggestions from code review

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
This commit is contained in:
Lunny Xiao 2022-06-16 11:33:23 +08:00 • committed by GitHub
parent 7d1770cd71
commit b01dce2a6e
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GPG key ID: 4AEE18F83AFDEB23
17 changed files with 248 additions and 93 deletions
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81
modules/markup/renderer.go
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@ -10,6 +10,7 @@ import (
"errors"
"fmt"
"io"
"net/url"
"path/filepath"
"strings"
"sync"
@ -43,17 +44,18 @@ type Header struct {
// RenderContext represents a render context
type RenderContext struct {
Ctx context.Context
Filename string
Type string
IsWiki bool
URLPrefix string
Metas map[string]string
DefaultLink string
GitRepo *git.Repository
ShaExistCache map[string]bool
cancelFn func()
TableOfContents []Header
Ctx context.Context
RelativePath string // relative path from tree root of the branch
Type string
IsWiki bool
URLPrefix string
Metas map[string]string
DefaultLink string
GitRepo *git.Repository
ShaExistCache map[string]bool
cancelFn func()
TableOfContents []Header
InStandalonePage bool // used by external render. the router "/org/repo/render/..." will output the rendered content in a standalone page
}
// Cancel runs any cleanup functions that have been registered for this Ctx
@ -88,12 +90,24 @@ func (ctx *RenderContext) AddCancel(fn func()) {
type Renderer interface {
Name() string // markup format name
Extensions() []string
NeedPostProcess() bool
SanitizerRules() []setting.MarkupSanitizerRule
SanitizerDisabled() bool
Render(ctx *RenderContext, input io.Reader, output io.Writer) error
}
// PostProcessRenderer defines an interface for renderers who need post process
type PostProcessRenderer interface {
NeedPostProcess() bool
}
// PostProcessRenderer defines an interface for external renderers
type ExternalRenderer interface {
// SanitizerDisabled disabled sanitize if return true
SanitizerDisabled() bool
// DisplayInIFrame represents whether render the content with an iframe
DisplayInIFrame() bool
}
// RendererContentDetector detects if the content can be rendered
// by specified renderer
type RendererContentDetector interface {
@ -142,7 +156,7 @@ func DetectRendererType(filename string, input io.Reader) string {
func Render(ctx *RenderContext, input io.Reader, output io.Writer) error {
if ctx.Type != "" {
return renderByType(ctx, input, output)
} else if ctx.Filename != "" {
} else if ctx.RelativePath != "" {
return renderFile(ctx, input, output)
}
return errors.New("Render options both filename and type missing")
@ -163,6 +177,27 @@ type nopCloser struct {
func (nopCloser) Close() error { return nil }
func renderIFrame(ctx *RenderContext, output io.Writer) error {
// set height="0" ahead, otherwise the scrollHeight would be max(150, realHeight)
// at the moment, only "allow-scripts" is allowed for sandbox mode.
// "allow-same-origin" should never be used, it leads to XSS attack, and it makes the JS in iframe can access parent window's config and CSRF token
// TODO: when using dark theme, if the rendered content doesn't have proper style, the default text color is black, which is not easy to read
_, err := io.WriteString(output, fmt.Sprintf(`
<iframe src="%s/%s/%s/render/%s/%s"
name="giteaExternalRender"
onload="this.height=giteaExternalRender.document.documentElement.scrollHeight"
width="100%%" height="0" scrolling="no" frameborder="0" style="overflow: hidden"
sandbox="allow-scripts"
></iframe>`,
setting.AppSubURL,
url.PathEscape(ctx.Metas["user"]),
url.PathEscape(ctx.Metas["repo"]),
ctx.Metas["BranchNameSubURL"],
url.PathEscape(ctx.RelativePath),
))
return err
}
func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Writer) error {
var wg sync.WaitGroup
var err error
@ -175,7 +210,12 @@ func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Wr
var pr2 io.ReadCloser
var pw2 io.WriteCloser
if !renderer.SanitizerDisabled() {
var sanitizerDisabled bool
if r, ok := renderer.(ExternalRenderer); ok {
sanitizerDisabled = r.SanitizerDisabled()
}
if !sanitizerDisabled {
pr2, pw2 = io.Pipe()
defer func() {
_ = pr2.Close()
@ -194,7 +234,7 @@ func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Wr
wg.Add(1)
go func() {
if renderer.NeedPostProcess() {
if r, ok := renderer.(PostProcessRenderer); ok && r.NeedPostProcess() {
err = PostProcess(ctx, pr, pw2)
} else {
_, err = io.Copy(pw2, pr)
@ -239,8 +279,15 @@ func (err ErrUnsupportedRenderExtension) Error() string {
}
func renderFile(ctx *RenderContext, input io.Reader, output io.Writer) error {
extension := strings.ToLower(filepath.Ext(ctx.Filename))
extension := strings.ToLower(filepath.Ext(ctx.RelativePath))
if renderer, ok := extRenderers[extension]; ok {
if r, ok := renderer.(ExternalRenderer); ok && r.DisplayInIFrame() {
if !ctx.InStandalonePage {
// for an external render, it could only output its content in a standalone page
// otherwise, a <iframe> should be outputted to embed the external rendered page
return renderIFrame(ctx, output)
}
}
return render(ctx, renderer, input, output)
}
return ErrUnsupportedRenderExtension{extension}