go-gitea · wxiaoguang · Oct 23, 2025 · Oct 22, 2025 · Oct 23, 2025 · Oct 23, 2025
diff --git a/custom/conf/app.example.ini b/custom/conf/app.example.ini
@@ -2541,6 +2541,12 @@ LEVEL = Info
 ;; * no-sanitizer: Disable the sanitizer and render the content inside current page. It's **insecure** and may lead to XSS attack if the content contains malicious code.
 ;; * iframe: Render the content in a separate standalone page and embed it into current page by iframe. The iframe is in sandbox mode with same-origin disabled, and the JS code are safely isolated from parent page.
 ;RENDER_CONTENT_MODE=sanitized
+;;
+;; Whether post-process the rendered HTML content, including:
+;; resolve relative links and image sources, recognizing issue/commit references, escaping invisible characters,
+;; mentioning users, rendering permlink code blocks, replacing emoji shorthands, etc.
+;; By default, this is true when RENDER_CONTENT_MODE is `sanitized`, otherwise false.
+;NEED_POST_PROCESS=false
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

diff --git a/modules/markup/external/external.go b/modules/markup/external/external.go
@@ -15,6 +15,8 @@ import (
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/process"
 	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/kballard/go-shellquote"
 )
 
 // RegisterRenderers registers all supported third part renderers according settings
@@ -81,7 +83,10 @@ func (p *Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.
 		envMark("GITEA_PREFIX_SRC"), baseLinkSrc,
 		envMark("GITEA_PREFIX_RAW"), baseLinkRaw,
 	).Replace(p.Command)
-	commands := strings.Fields(command)
+	commands, err := shellquote.Split(command)
+	if err != nil || len(commands) == 0 {
+		return fmt.Errorf("%s invalid command %q: %w", p.Name(), p.Command, err)
+	}
 	args := commands[1:]
 
 	if p.IsInputFile {

diff --git a/modules/markup/internal/finalprocessor.go b/modules/markup/internal/finalprocessor.go
@@ -5,11 +5,13 @@ package internal
 
 import (
 	"bytes"
+	"html/template"
 	"io"
 )
 
 type finalProcessor struct {
 	renderInternal *RenderInternal
+	extraHeadHTML  template.HTML
 
 	output io.Writer
 	buf    bytes.Buffer
@@ -25,6 +27,32 @@ func (p *finalProcessor) Close() error {
 	// because "postProcess" already does so. In the future we could optimize the code to process data on the fly.
 	buf := p.buf.Bytes()
 	buf = bytes.ReplaceAll(buf, []byte(` data-attr-class="`+p.renderInternal.secureIDPrefix), []byte(` class="`))
-	_, err := p.output.Write(buf)
+
+	tmp := bytes.TrimSpace(buf)
+	isLikelyHTML := len(tmp) != 0 && tmp[0] == '<' && tmp[len(tmp)-1] == '>' && bytes.Index(tmp, []byte(`</`)) > 0
+	if !isLikelyHTML {
+		// not HTML, write back directly
+		_, err := p.output.Write(buf)
+		return err
+	}
+
+	// add our extra head HTML into output
+	headBytes := []byte("<head>")
+	posHead := bytes.Index(buf, headBytes)
+	var part1, part2 []byte
+	if posHead >= 0 {
+		part1, part2 = buf[:posHead+len(headBytes)], buf[posHead+len(headBytes):]
+	} else {
+		part1, part2 = nil, buf
+	}
+	if len(part1) > 0 {
+		if _, err := p.output.Write(part1); err != nil {
+			return err
+		}
+	}
+	if _, err := io.WriteString(p.output, string(p.extraHeadHTML)); err != nil {
+		return err
+	}
+	_, err := p.output.Write(part2)
 	return err
 }
diff --git a/modules/markup/internal/internal_test.go b/modules/markup/internal/internal_test.go
@@ -12,7 +12,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestRenderInternal(t *testing.T) {
+func TestRenderInternalAttrs(t *testing.T) {
 	cases := []struct {
 		input, protected, recovered string
 	}{
@@ -30,7 +30,7 @@ func TestRenderInternal(t *testing.T) {
 	for _, c := range cases {
 		var r RenderInternal
 		out := &bytes.Buffer{}
-		in := r.init("sec", out)
+		in := r.init("sec", out, "")
 		protected := r.ProtectSafeAttrs(template.HTML(c.input))
 		assert.EqualValues(t, c.protected, protected)
 		_, _ = io.WriteString(in, string(protected))
@@ -41,7 +41,7 @@ func TestRenderInternal(t *testing.T) {
 	var r1, r2 RenderInternal
 	protected := r1.ProtectSafeAttrs(`<div class="test"></div>`)
 	assert.EqualValues(t, `<div class="test"></div>`, protected, "non-initialized RenderInternal should not protect any attributes")
-	_ = r1.init("sec", nil)
+	_ = r1.init("sec", nil, "")
 	protected = r1.ProtectSafeAttrs(`<div class="test"></div>`)
 	assert.EqualValues(t, `<div data-attr-class="sec:test"></div>`, protected)
 	assert.Equal(t, "data-attr-class", r1.SafeAttr("class"))
@@ -54,8 +54,37 @@ func TestRenderInternal(t *testing.T) {
 	assert.Empty(t, recovered)
 
 	out2 := &bytes.Buffer{}
-	in2 := r2.init("sec-other", out2)
+	in2 := r2.init("sec-other", out2, "")
 	_, _ = io.WriteString(in2, string(protected))
 	_ = in2.Close()
 	assert.Equal(t, `<div data-attr-class="sec:test"></div>`, out2.String(), "different secureID should not recover the value")
 }
+
+func TestRenderInternalExtraHead(t *testing.T) {
+	t.Run("HeadExists", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		var r RenderInternal
+		in := r.init("sec", out, `<MY-TAG>`)
+		_, _ = io.WriteString(in, `<head>any</head>`)
+		_ = in.Close()
+		assert.Equal(t, `<head><MY-TAG>any</head>`, out.String())
+	})
+
+	t.Run("HeadNotExists", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		var r RenderInternal
+		in := r.init("sec", out, `<MY-TAG>`)
+		_, _ = io.WriteString(in, `<div></div>`)
+		_ = in.Close()
+		assert.Equal(t, `<MY-TAG><div></div>`, out.String())
+	})
+
+	t.Run("NotHTML", func(t *testing.T) {
+		out := &bytes.Buffer{}
+		var r RenderInternal
+		in := r.init("sec", out, `<MY-TAG>`)
+		_, _ = io.WriteString(in, `<any>`)
+		_ = in.Close()
+		assert.Equal(t, `<any>`, out.String())
+	})
+}
diff --git a/modules/markup/internal/renderinternal.go b/modules/markup/internal/renderinternal.go
@@ -29,19 +29,19 @@ type RenderInternal struct {
 	secureIDPrefix string
 }
 
-func (r *RenderInternal) Init(output io.Writer) io.WriteCloser {
+func (r *RenderInternal) Init(output io.Writer, extraHeadHTML template.HTML) io.WriteCloser {
 	buf := make([]byte, 12)
 	_, err := rand.Read(buf)
 	if err != nil {
 		panic("unable to generate secure id")
 	}
-	return r.init(base64.URLEncoding.EncodeToString(buf), output)
+	return r.init(base64.URLEncoding.EncodeToString(buf), output, extraHeadHTML)
 }
 
-func (r *RenderInternal) init(secID string, output io.Writer) io.WriteCloser {
+func (r *RenderInternal) init(secID string, output io.Writer, extraHeadHTML template.HTML) io.WriteCloser {
 	r.secureID = secID
 	r.secureIDPrefix = r.secureID + ":"
-	return &finalProcessor{renderInternal: r, output: output}
+	return &finalProcessor{renderInternal: r, output: output, extraHeadHTML: extraHeadHTML}
 }
 
 func (r *RenderInternal) RecoverProtectedValue(v string) (string, bool) {

diff --git a/modules/markup/render.go b/modules/markup/render.go
@@ -6,12 +6,14 @@ package markup
 import (
 	"context"
 	"fmt"
+	"html/template"
 	"io"
 	"net/url"
 	"strconv"
 	"strings"
 	"time"
 
+	"code.gitea.io/gitea/modules/htmlutil"
 	"code.gitea.io/gitea/modules/markup/internal"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
@@ -120,31 +122,38 @@ func (ctx *RenderContext) WithHelper(helper RenderHelper) *RenderContext {
 	return ctx
 }
 
-// Render renders markup file to HTML with all specific handling stuff.
-func Render(ctx *RenderContext, input io.Reader, output io.Writer) error {
+// FindRendererByContext finds renderer by RenderContext
+// TODO: it should be merged with other similar functions like GetRendererByFileName, DetectMarkupTypeByFileName, etc
+func FindRendererByContext(ctx *RenderContext) (Renderer, error) {
 	if ctx.RenderOptions.MarkupType == "" && ctx.RenderOptions.RelativePath != "" {
 		ctx.RenderOptions.MarkupType = DetectMarkupTypeByFileName(ctx.RenderOptions.RelativePath)
 		if ctx.RenderOptions.MarkupType == "" {
-			return util.NewInvalidArgumentErrorf("unsupported file to render: %q", ctx.RenderOptions.RelativePath)
+			return nil, util.NewInvalidArgumentErrorf("unsupported file to render: %q", ctx.RenderOptions.RelativePath)
 		}
 	}
 
 	renderer := renderers[ctx.RenderOptions.MarkupType]
 	if renderer == nil {
-		return util.NewInvalidArgumentErrorf("unsupported markup type: %q", ctx.RenderOptions.MarkupType)
+		return nil, util.NewNotExistErrorf("unsupported markup type: %q", ctx.RenderOptions.MarkupType)
 	}
 
-	if ctx.RenderOptions.RelativePath != "" {
-		if externalRender, ok := renderer.(ExternalRenderer); ok && externalRender.DisplayInIFrame() {
-			if !ctx.RenderOptions.InStandalonePage {
-				// for an external "DisplayInIFrame" 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 renderer, nil
+}
+
+func RendererNeedPostProcess(renderer Renderer) bool {
+	if r, ok := renderer.(PostProcessRenderer); ok && r.NeedPostProcess() {
+		return true
 	}
+	return false
+}
 
-	return render(ctx, renderer, input, output)
+// Render renders markup file to HTML with all specific handling stuff.
+func Render(ctx *RenderContext, input io.Reader, output io.Writer) error {
+	renderer, err := FindRendererByContext(ctx)
+	if err != nil {
+		return err
+	}
+	return RenderWithRenderer(ctx, renderer, input, output)
 }
 
 // RenderString renders Markup string to HTML with all specific handling stuff and return string
@@ -157,23 +166,28 @@ func RenderString(ctx *RenderContext, content string) (string, error) {
 }
 
 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,
+	src := fmt.Sprintf("%s/%s/%s/render/%s/%s", setting.AppSubURL,
 		url.PathEscape(ctx.RenderOptions.Metas["user"]),
 		url.PathEscape(ctx.RenderOptions.Metas["repo"]),
-		ctx.RenderOptions.Metas["RefTypeNameSubURL"],
-		url.PathEscape(ctx.RenderOptions.RelativePath),
-	))
+		util.PathEscapeSegments(ctx.RenderOptions.Metas["RefTypeNameSubURL"]),
+		util.PathEscapeSegments(ctx.RenderOptions.RelativePath),
+	)
+
+	defaultWidth := "100%"
+	defaultHeight := "300"
+
+	// ATTENTION! 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
+	iframe := htmlutil.HTMLFormat(`
+<iframe data-src="%s"
+	class="external-render-iframe"
+	sandbox="allow-scripts allow-popups"
+	width="%s" height="%s"
+></iframe>
+`,
+		src, defaultWidth, defaultHeight)
+
+	_, err := io.WriteString(output, string(iframe))
 	return err
 }
 
@@ -185,13 +199,27 @@ func pipes() (io.ReadCloser, io.WriteCloser, func()) {
 	}
 }
 
-func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Writer) error {
+func RenderWithRenderer(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Writer) error {
+	var extraHeadHTML template.HTML
+	if externalRender, ok := renderer.(ExternalRenderer); ok && externalRender.DisplayInIFrame() {
+		if !ctx.RenderOptions.InStandalonePage {
+			// for an external "DisplayInIFrame" 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)
+		}
+		// else: this is a standalone page, fallthrough to the real rendering, and add extra JS/CSS
+		extraStyleHref := setting.AppSubURL + "/assets/css/external-render-iframe.css"
+		extraScriptSrc := setting.AppSubURL + "/assets/js/external-render-iframe.js"
+		// "<script>" must go before "<link>", to make Golang's http.DetectContentType() can still recognize the content as "text/html"
+		extraHeadHTML = htmlutil.HTMLFormat(`<script src="%s"></script><link rel="stylesheet" href="%s">`, extraScriptSrc, extraStyleHref)
+	}
+
 	ctx.usedByRender = true
 	if ctx.RenderHelper != nil {
 		defer ctx.RenderHelper.CleanUp()
 	}
 
-	finalProcessor := ctx.RenderInternal.Init(output)
+	finalProcessor := ctx.RenderInternal.Init(output, extraHeadHTML)
 	defer finalProcessor.Close()
 
 	// input -> (pw1=pr1) -> renderer -> (pw2=pr2) -> SanitizeReader -> finalProcessor -> output
@@ -214,7 +242,7 @@ func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Wr
 	}
 
 	eg.Go(func() (err error) {
-		if r, ok := renderer.(PostProcessRenderer); ok && r.NeedPostProcess() {
+		if RendererNeedPostProcess(renderer) {
 			err = PostProcessDefault(ctx, pr1, pw2)
 		} else {
 			_, err = io.Copy(pw2, pr1)

diff --git a/modules/setting/markup.go b/modules/setting/markup.go
@@ -259,7 +259,9 @@ func newMarkupRenderer(name string, sec ConfigSection) {
 		FileExtensions:    exts,
 		Command:           command,
 		IsInputFile:       sec.Key("IS_INPUT_FILE").MustBool(false),
-		NeedPostProcess:   sec.Key("NEED_POSTPROCESS").MustBool(true),
 		RenderContentMode: renderContentMode,
+
+		// if no sanitizer is needed, no post process is needed
+		NeedPostProcess: sec.Key("NEED_POST_PROCESS").MustBool(renderContentMode == RenderContentModeSanitized),
 	})
 }
diff --git a/routers/web/repo/render.go b/routers/web/repo/render.go
@@ -52,7 +52,7 @@ func RenderFile(ctx *context.Context) {
 	isTextFile := st.IsText()
 
 	rd := charset.ToUTF8WithFallbackReader(io.MultiReader(bytes.NewReader(buf), dataRc), charset.ConvertOpts{})
-	ctx.Resp.Header().Add("Content-Security-Policy", "frame-src 'self'; sandbox allow-scripts")
+	ctx.Resp.Header().Add("Content-Security-Policy", "frame-src 'self'; sandbox allow-scripts allow-popups")
 
 	if markupType := markup.DetectMarkupTypeByFileName(blob.Name()); markupType == "" {
 		if isTextFile {

diff --git a/routers/web/repo/view.go b/routers/web/repo/view.go
@@ -151,17 +151,28 @@ func loadLatestCommitData(ctx *context.Context, latestCommit *git.Commit) bool {
 }
 
 func markupRender(ctx *context.Context, renderCtx *markup.RenderContext, input io.Reader) (escaped *charset.EscapeStatus, output template.HTML, err error) {
+	renderer, err := markup.FindRendererByContext(renderCtx)
+	if err != nil {
+		return nil, "", err
+	}
+
 	markupRd, markupWr := io.Pipe()
 	defer markupWr.Close()
+
 	done := make(chan struct{})
 	go func() {
 		sb := &strings.Builder{}
-		// We allow NBSP here this is rendered
-		escaped, _ = charset.EscapeControlReader(markupRd, sb, ctx.Locale, charset.RuneNBSP)
+		if markup.RendererNeedPostProcess(renderer) {
+			escaped, _ = charset.EscapeControlReader(markupRd, sb, ctx.Locale, charset.RuneNBSP) // We allow NBSP here this is rendered
+		} else {
+			escaped = &charset.EscapeStatus{}
+			_, _ = io.Copy(sb, markupRd)
+		}
 		output = template.HTML(sb.String())
 		close(done)
 	}()
-	err = markup.Render(renderCtx, input, markupWr)
+
+	err = markup.RenderWithRenderer(renderCtx, renderer, input, markupWr)
 	_ = markupWr.CloseWithError(err)
 	<-done
 	return escaped, output, err