From a09b40de8d1dae7107437cfba42cee201fcd6d42 Mon Sep 17 00:00:00 2001 From: KN4CK3R Date: Fri, 19 Nov 2021 11:46:47 +0100 Subject: [PATCH] Prevent double sanitize (#16386) * Prevent double sanitize. * Use SanitizeReaderToWriter. At the moment `actualRender` uses `SanitizeReader` to sanitize the output. But `SanitizeReader` gets called in `markup.render` too so the output gets sanitized twice. I moved the `SanitizeReader` call into `RenderRaw` because this method does not use `markup.render`. I would like to remove the `RenderRaw`/`RenderRawString` methods too because they are only called from tests, the fuzzer and the `/markup/raw` api endpoint. This endpoint is not in use so I think we could remove them. If we really in the future need a method to render markdown without PostProcessing we could achieve this with a more flexible `renderer.NeedPostProcess` method. --- modules/markup/markdown/markdown.go | 104 ++++++++++++---------------- modules/markup/renderer.go | 3 +- modules/markup/sanitizer.go | 5 +- 3 files changed, 48 insertions(+), 64 deletions(-) diff --git a/modules/markup/markdown/markdown.go b/modules/markup/markdown/markdown.go index 2574585573..5ce36a1d16 100644 --- a/modules/markup/markdown/markdown.go +++ b/modules/markup/markdown/markdown.go @@ -35,13 +35,8 @@ var urlPrefixKey = parser.NewContextKey() var isWikiKey = parser.NewContextKey() var renderMetasKey = parser.NewContextKey() -type closesWithError interface { - io.WriteCloser - CloseWithError(err error) error -} - type limitWriter struct { - w closesWithError + w io.Writer sum int64 limit int64 } @@ -55,7 +50,6 @@ func (l *limitWriter) Write(data []byte) (int, error) { if err != nil { return n, err } - _ = l.w.Close() return n, fmt.Errorf("Rendered content too large - truncating render") } n, err := l.w.Write(data) @@ -63,16 +57,6 @@ func (l *limitWriter) Write(data []byte) (int, error) { return n, err } -// Close closes the writer -func (l *limitWriter) Close() error { - return l.w.Close() -} - -// CloseWithError closes the writer -func (l *limitWriter) CloseWithError(err error) error { - return l.w.CloseWithError(err) -} - // newParserContext creates a parser.Context with the render context set func newParserContext(ctx *markup.RenderContext) parser.Context { pc := parser.NewContext(parser.WithIDs(newPrefixedIDs())) @@ -153,51 +137,40 @@ func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer) }) - rd, wr := io.Pipe() - defer func() { - _ = rd.Close() - _ = wr.Close() - }() - lw := &limitWriter{ - w: wr, + w: output, limit: setting.UI.MaxDisplayFileSize * 3, } - // FIXME: should we include a timeout that closes the pipe to abort the renderer and sanitizer if it takes too long? - go func() { - defer func() { - err := recover() - if err == nil { - return - } - - log.Warn("Unable to render markdown due to panic in goldmark: %v", err) - if log.IsDebug() { - log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2))) - } - _ = lw.CloseWithError(fmt.Errorf("%v", err)) - }() - - // FIXME: Don't read all to memory, but goldmark doesn't support - pc := newParserContext(ctx) - buf, err := io.ReadAll(input) - if err != nil { - log.Error("Unable to ReadAll: %v", err) + // FIXME: should we include a timeout to abort the renderer if it takes too long? + defer func() { + err := recover() + if err == nil { return } - if err := converter.Convert(giteautil.NormalizeEOL(buf), lw, parser.WithContext(pc)); err != nil { - log.Error("Unable to render: %v", err) - _ = lw.CloseWithError(err) - return + + log.Warn("Unable to render markdown due to panic in goldmark: %v", err) + if log.IsDebug() { + log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2))) } - _ = lw.Close() }() - buf := markup.SanitizeReader(rd, "") - _, err := io.Copy(output, buf) - return err + + // FIXME: Don't read all to memory, but goldmark doesn't support + pc := newParserContext(ctx) + buf, err := io.ReadAll(input) + if err != nil { + log.Error("Unable to ReadAll: %v", err) + return err + } + if err := converter.Convert(giteautil.NormalizeEOL(buf), lw, parser.WithContext(pc)); err != nil { + log.Error("Unable to render: %v", err) + return err + } + + return nil } +// Note: The output of this method must get sanitized. func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { defer func() { err := recover() @@ -205,14 +178,13 @@ func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error return } - log.Warn("Unable to render markdown due to panic in goldmark - will return sanitized raw bytes") + log.Warn("Unable to render markdown due to panic in goldmark - will return raw bytes") if log.IsDebug() { log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2))) } - ret := markup.SanitizeReader(input, "") - _, err = io.Copy(output, ret) + _, err = io.Copy(output, input) if err != nil { - log.Error("SanitizeReader failed: %v", err) + log.Error("io.Copy failed: %v", err) } }() return actualRender(ctx, input, output) @@ -255,8 +227,8 @@ func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Wri // Render renders Markdown to HTML with all specific handling stuff. func Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { - if ctx.Filename == "" { - ctx.Filename = "a.md" + if ctx.Type == "" { + ctx.Type = MarkupName } return markup.Render(ctx, input, output) } @@ -272,7 +244,21 @@ func RenderString(ctx *markup.RenderContext, content string) (string, error) { // RenderRaw renders Markdown to HTML without handling special links. func RenderRaw(ctx *markup.RenderContext, input io.Reader, output io.Writer) error { - return render(ctx, input, output) + rd, wr := io.Pipe() + defer func() { + _ = rd.Close() + _ = wr.Close() + }() + + go func() { + if err := render(ctx, input, wr); err != nil { + _ = wr.CloseWithError(err) + return + } + _ = wr.Close() + }() + + return markup.SanitizeReader(rd, "", output) } // RenderRawString renders Markdown to HTML without handling special links and return string diff --git a/modules/markup/renderer.go b/modules/markup/renderer.go index 3cd7cea700..0ac0daaea9 100644 --- a/modules/markup/renderer.go +++ b/modules/markup/renderer.go @@ -144,8 +144,7 @@ func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Wr wg.Add(1) go func() { - buf := SanitizeReader(pr2, renderer.Name()) - _, err = io.Copy(output, buf) + err = SanitizeReader(pr2, renderer.Name(), output) _ = pr2.Close() wg.Done() }() diff --git a/modules/markup/sanitizer.go b/modules/markup/sanitizer.go index 5ff26a3109..92dd19f0a1 100644 --- a/modules/markup/sanitizer.go +++ b/modules/markup/sanitizer.go @@ -6,7 +6,6 @@ package markup import ( - "bytes" "io" "regexp" "sync" @@ -149,11 +148,11 @@ func Sanitize(s string) string { } // SanitizeReader sanitizes a Reader -func SanitizeReader(r io.Reader, renderer string) *bytes.Buffer { +func SanitizeReader(r io.Reader, renderer string, w io.Writer) error { NewSanitizer() policy, exist := sanitizer.rendererPolicies[renderer] if !exist { policy = sanitizer.defaultPolicy } - return policy.SanitizeReader(r) + return policy.SanitizeReaderToWriter(r, w) }