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Add sanitizer rules per renderer (#16110)

* Added sanitizer rules per renderer.

* Updated documentation.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
master
KN4CK3R 1 year ago
committed by GitHub
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c9c7afda1a
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  1. 4
      docs/content/doc/advanced/config-cheat-sheet.en-us.md
  2. 41
      docs/content/doc/advanced/external-renderers.en-us.md
  3. 10
      modules/markup/csv/csv.go
  4. 7
      modules/markup/external/external.go
  5. 4
      modules/markup/html_test.go
  6. 9
      modules/markup/markdown/markdown.go
  7. 6
      modules/markup/orgmode/orgmode.go
  8. 56
      modules/markup/renderer.go
  9. 88
      modules/markup/sanitizer.go
  10. 103
      modules/setting/markup.go

4
docs/content/doc/advanced/config-cheat-sheet.en-us.md

@ -907,13 +907,17 @@ Gitea supports customizing the sanitization policy for rendered HTML. The exampl
ELEMENT = span
ALLOW_ATTR = class
REGEXP = ^\s*((math(\s+|$)|inline(\s+|$)|display(\s+|$)))+
ALLOW_DATA_URI_IMAGES = true
```
- `ELEMENT`: The element this policy applies to. Must be non-empty.
- `ALLOW_ATTR`: The attribute this policy allows. Must be non-empty.
- `REGEXP`: A regex to match the contents of the attribute against. Must be present but may be empty for unconditional whitelisting of this attribute.
- `ALLOW_DATA_URI_IMAGES`: **false** Allow data uri images (`<img src="data:image/png;base64,..."/>`).
Multiple sanitisation rules can be defined by adding unique subsections, e.g. `[markup.sanitizer.TeX-2]`.
To apply a sanitisation rules only for a specify external renderer they must use the renderer name, e.g. `[markup.sanitizer.asciidoc.rule-1]`.
If the rule is defined above the renderer ini section or the name does not match a renderer it is applied to every renderer.
## Time (`time`)

41
docs/content/doc/advanced/external-renderers.en-us.md

@ -64,8 +64,8 @@ IS_INPUT_FILE = false
[markup.jupyter]
ENABLED = true
FILE_EXTENSIONS = .ipynb
RENDER_COMMAND = "jupyter nbconvert --stdout --to html --template basic "
IS_INPUT_FILE = true
RENDER_COMMAND = "jupyter nbconvert --stdin --stdout --to html --template basic"
IS_INPUT_FILE = false
[markup.restructuredtext]
ENABLED = true
@ -90,15 +90,50 @@ FILE_EXTENSIONS = .md,.markdown
RENDER_COMMAND = pandoc -f markdown -t html --katex
```
You must define `ELEMENT`, `ALLOW_ATTR`, and `REGEXP` in each section.
You must define `ELEMENT` and `ALLOW_ATTR` in each section.
To define multiple entries, add a unique alphanumeric suffix (e.g., `[markup.sanitizer.1]` and `[markup.sanitizer.something]`).
To apply a sanitisation rules only for a specify external renderer they must use the renderer name, e.g. `[markup.sanitizer.asciidoc.rule-1]`, `[markup.sanitizer.<renderer>.rule-1]`.
**Note**: If the rule is defined above the renderer ini section or the name does not match a renderer it is applied to every renderer.
Once your configuration changes have been made, restart Gitea to have changes take effect.
**Note**: Prior to Gitea 1.12 there was a single `markup.sanitiser` section with keys that were redefined for multiple rules, however,
there were significant problems with this method of configuration necessitating configuration through multiple sections.
### Example: Office DOCX
Display Office DOCX files with [`pandoc`](https://pandoc.org/):
```ini
[markup.docx]
ENABLED = true
FILE_EXTENSIONS = .docx
RENDER_COMMAND = "pandoc --from docx --to html --self-contained --template /path/to/basic.html"
[markup.sanitizer.docx.img]
ALLOW_DATA_URI_IMAGES = true
```
The template file has the following content:
```
$body$
```
### Example: Jupyter Notebook
Display Jupyter Notebook files with [`nbconvert`](https://github.com/jupyter/nbconvert):
```ini
[markup.jupyter]
ENABLED = true
FILE_EXTENSIONS = .ipynb
RENDER_COMMAND = "jupyter-nbconvert --stdin --stdout --to html --template basic"
[markup.sanitizer.jupyter.img]
ALLOW_DATA_URI_IMAGES = true
```
## Customizing CSS
The external renderer is specified in the .ini in the format `[markup.XXXXX]` and the HTML supplied by your external renderer will be wrapped in a `<div>` with classes `markup` and `XXXXX`. The `markup` class provides out of the box styling (as does `markdown` if `XXXXX` is `markdown`). Otherwise you can use these classes to specifically target the contents of your rendered HTML.

10
modules/markup/csv/csv.go

@ -10,6 +10,7 @@ import (
"html"
"io"
"io/ioutil"
"regexp"
"strconv"
"code.gitea.io/gitea/modules/csv"
@ -38,6 +39,15 @@ func (Renderer) Extensions() []string {
return []string{".csv", ".tsv"}
}
// SanitizerRules implements markup.Renderer
func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
return []setting.MarkupSanitizerRule{
{Element: "table", AllowAttr: "class", Regexp: regexp.MustCompile(`data-table`)},
{Element: "th", AllowAttr: "class", Regexp: regexp.MustCompile(`line-num`)},
{Element: "td", AllowAttr: "class", Regexp: regexp.MustCompile(`line-num`)},
}
}
func writeField(w io.Writer, element, class, field string) error {
if _, err := io.WriteString(w, "<"); err != nil {
return err

7
modules/markup/external/external.go

@ -30,7 +30,7 @@ func RegisterRenderers() {
// Renderer implements markup.Renderer for external tools
type Renderer struct {
setting.MarkupRenderer
*setting.MarkupRenderer
}
// Name returns the external tool name
@ -48,6 +48,11 @@ func (p *Renderer) Extensions() []string {
return p.FileExtensions
}
// SanitizerRules implements markup.Renderer
func (p *Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
return p.MarkupSanitizerRules
}
func envMark(envName string) string {
if runtime.GOOS == "windows" {
return "%" + envName + "%"

4
modules/markup/html_test.go

@ -112,7 +112,7 @@ func TestRender_links(t *testing.T) {
defaultCustom := setting.Markdown.CustomURLSchemes
setting.Markdown.CustomURLSchemes = []string{"ftp", "magnet"}
ReplaceSanitizer()
InitializeSanitizer()
CustomLinkURLSchemes(setting.Markdown.CustomURLSchemes)
test(
@ -192,7 +192,7 @@ func TestRender_links(t *testing.T) {
// Restore previous settings
setting.Markdown.CustomURLSchemes = defaultCustom
ReplaceSanitizer()
InitializeSanitizer()
CustomLinkURLSchemes(setting.Markdown.CustomURLSchemes)
}

9
modules/markup/markdown/markdown.go

@ -199,7 +199,7 @@ func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer)
}
_ = lw.Close()
}()
buf := markup.SanitizeReader(rd)
buf := markup.SanitizeReader(rd, "")
_, err := io.Copy(output, buf)
return err
}
@ -215,7 +215,7 @@ func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error
if log.IsDebug() {
log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2)))
}
ret := markup.SanitizeReader(input)
ret := markup.SanitizeReader(input, "")
_, err = io.Copy(output, ret)
if err != nil {
log.Error("SanitizeReader failed: %v", err)
@ -249,6 +249,11 @@ func (Renderer) Extensions() []string {
return setting.Markdown.FileExtensions
}
// SanitizerRules implements markup.Renderer
func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
return []setting.MarkupSanitizerRule{}
}
// Render implements markup.Renderer
func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
return render(ctx, input, output)

6
modules/markup/orgmode/orgmode.go

@ -13,6 +13,7 @@ import (
"code.gitea.io/gitea/modules/highlight"
"code.gitea.io/gitea/modules/markup"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
"github.com/alecthomas/chroma"
@ -41,6 +42,11 @@ func (Renderer) Extensions() []string {
return []string{".org"}
}
// SanitizerRules implements markup.Renderer
func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
return []setting.MarkupSanitizerRule{}
}
// Render renders orgmode rawbytes to HTML
func Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
htmlWriter := org.NewHTMLWriter()

56
modules/markup/renderer.go

@ -81,6 +81,7 @@ type Renderer interface {
Name() string // markup format name
Extensions() []string
NeedPostProcess() bool
SanitizerRules() []setting.MarkupSanitizerRule
Render(ctx *RenderContext, input io.Reader, output io.Writer) error
}
@ -136,37 +137,32 @@ func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Wr
_ = pw.Close()
}()
if renderer.NeedPostProcess() {
pr2, pw2 := io.Pipe()
defer func() {
_ = pr2.Close()
_ = pw2.Close()
}()
wg.Add(1)
go func() {
buf := SanitizeReader(pr2)
_, err = io.Copy(output, buf)
_ = pr2.Close()
wg.Done()
}()
wg.Add(1)
go func() {
pr2, pw2 := io.Pipe()
defer func() {
_ = pr2.Close()
_ = pw2.Close()
}()
wg.Add(1)
go func() {
buf := SanitizeReader(pr2, renderer.Name())
_, err = io.Copy(output, buf)
_ = pr2.Close()
wg.Done()
}()
wg.Add(1)
go func() {
if renderer.NeedPostProcess() {
err = PostProcess(ctx, pr, pw2)
_ = pr.Close()
_ = pw2.Close()
wg.Done()
}()
} else {
wg.Add(1)
go func() {
buf := SanitizeReader(pr)
_, err = io.Copy(output, buf)
_ = pr.Close()
wg.Done()
}()
}
} else {
_, err = io.Copy(pw2, pr)
}
_ = pr.Close()
_ = pw2.Close()
wg.Done()
}()
if err1 := renderer.Render(ctx, input, pw); err1 != nil {
return err1
}

88
modules/markup/sanitizer.go

@ -19,8 +19,9 @@ import (
// Sanitizer is a protection wrapper of *bluemonday.Policy which does not allow
// any modification to the underlying policies once it's been created.
type Sanitizer struct {
policy *bluemonday.Policy
init sync.Once
defaultPolicy *bluemonday.Policy
rendererPolicies map[string]*bluemonday.Policy
init sync.Once
}
var sanitizer = &Sanitizer{}
@ -30,47 +31,57 @@ var sanitizer = &Sanitizer{}
// entire application lifecycle.
func NewSanitizer() {
sanitizer.init.Do(func() {
ReplaceSanitizer()
InitializeSanitizer()
})
}
// ReplaceSanitizer replaces the current sanitizer to account for changes in settings
func ReplaceSanitizer() {
sanitizer.policy = bluemonday.UGCPolicy()
// InitializeSanitizer (re)initializes the current sanitizer to account for changes in settings
func InitializeSanitizer() {
sanitizer.rendererPolicies = map[string]*bluemonday.Policy{}
sanitizer.defaultPolicy = createDefaultPolicy()
for name, renderer := range renderers {
sanitizerRules := renderer.SanitizerRules()
if len(sanitizerRules) > 0 {
policy := createDefaultPolicy()
addSanitizerRules(policy, sanitizerRules)
sanitizer.rendererPolicies[name] = policy
}
}
}
func createDefaultPolicy() *bluemonday.Policy {
policy := bluemonday.UGCPolicy()
// For Chroma markdown plugin
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`^is-loading$`)).OnElements("pre")
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(chroma )?language-[\w-]+$`)).OnElements("code")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^is-loading$`)).OnElements("pre")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(chroma )?language-[\w-]+$`)).OnElements("code")
// Checkboxes
sanitizer.policy.AllowAttrs("type").Matching(regexp.MustCompile(`^checkbox$`)).OnElements("input")
sanitizer.policy.AllowAttrs("checked", "disabled", "data-source-position").OnElements("input")
policy.AllowAttrs("type").Matching(regexp.MustCompile(`^checkbox$`)).OnElements("input")
policy.AllowAttrs("checked", "disabled", "data-source-position").OnElements("input")
// Custom URL-Schemes
if len(setting.Markdown.CustomURLSchemes) > 0 {
sanitizer.policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
}
// Allow classes for anchors
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`ref-issue`)).OnElements("a")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`ref-issue`)).OnElements("a")
// Allow classes for task lists
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`task-list-item`)).OnElements("li")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`task-list-item`)).OnElements("li")
// Allow icons
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`^icon(\s+[\p{L}\p{N}_-]+)+$`)).OnElements("i")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^icon(\s+[\p{L}\p{N}_-]+)+$`)).OnElements("i")
// Allow unlabelled labels
sanitizer.policy.AllowNoAttrs().OnElements("label")
policy.AllowNoAttrs().OnElements("label")
// Allow classes for emojis
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`emoji`)).OnElements("img")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`emoji`)).OnElements("img")
// Allow icons, emojis, chroma syntax and keyword markup on span
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`^((icon(\s+[\p{L}\p{N}_-]+)+)|(emoji))$|^([a-z][a-z0-9]{0,2})$|^` + keywordClass + `$`)).OnElements("span")
// Allow data tables
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`data-table`)).OnElements("table")
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`line-num`)).OnElements("th", "td")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^((icon(\s+[\p{L}\p{N}_-]+)+)|(emoji))$|^([a-z][a-z0-9]{0,2})$|^` + keywordClass + `$`)).OnElements("span")
// Allow generally safe attributes
generalSafeAttrs := []string{"abbr", "accept", "accept-charset",
@ -101,18 +112,29 @@ func ReplaceSanitizer() {
"abbr", "bdo", "cite", "dfn", "mark", "small", "span", "time", "wbr",
}
sanitizer.policy.AllowAttrs(generalSafeAttrs...).OnElements(generalSafeElements...)
policy.AllowAttrs(generalSafeAttrs...).OnElements(generalSafeElements...)
sanitizer.policy.AllowAttrs("itemscope", "itemtype").OnElements("div")
policy.AllowAttrs("itemscope", "itemtype").OnElements("div")
// FIXME: Need to handle longdesc in img but there is no easy way to do it
// Custom keyword markup
for _, rule := range setting.ExternalSanitizerRules {
if rule.Regexp != nil {
sanitizer.policy.AllowAttrs(rule.AllowAttr).Matching(rule.Regexp).OnElements(rule.Element)
} else {
sanitizer.policy.AllowAttrs(rule.AllowAttr).OnElements(rule.Element)
addSanitizerRules(policy, setting.ExternalSanitizerRules)
return policy
}
func addSanitizerRules(policy *bluemonday.Policy, rules []setting.MarkupSanitizerRule) {
for _, rule := range rules {
if rule.AllowDataURIImages {
policy.AllowDataURIImages()
}
if rule.Element != "" {
if rule.Regexp != nil {
policy.AllowAttrs(rule.AllowAttr).Matching(rule.Regexp).OnElements(rule.Element)
} else {
policy.AllowAttrs(rule.AllowAttr).OnElements(rule.Element)
}
}
}
}
@ -120,11 +142,15 @@ func ReplaceSanitizer() {
// Sanitize takes a string that contains a HTML fragment or document and applies policy whitelist.
func Sanitize(s string) string {
NewSanitizer()
return sanitizer.policy.Sanitize(s)
return sanitizer.defaultPolicy.Sanitize(s)
}
// SanitizeReader sanitizes a Reader
func SanitizeReader(r io.Reader) *bytes.Buffer {
func SanitizeReader(r io.Reader, renderer string) *bytes.Buffer {
NewSanitizer()
return sanitizer.policy.SanitizeReader(r)
policy, exist := sanitizer.rendererPolicies[renderer]
if !exist {
policy = sanitizer.defaultPolicy
}
return policy.SanitizeReader(r)
}

103
modules/setting/markup.go

@ -15,31 +15,34 @@ import (
// ExternalMarkupRenderers represents the external markup renderers
var (
ExternalMarkupRenderers []MarkupRenderer
ExternalMarkupRenderers []*MarkupRenderer
ExternalSanitizerRules []MarkupSanitizerRule
)
// MarkupRenderer defines the external parser configured in ini
type MarkupRenderer struct {
Enabled bool
MarkupName string
Command string
FileExtensions []string
IsInputFile bool
NeedPostProcess bool
Enabled bool
MarkupName string
Command string
FileExtensions []string
IsInputFile bool
NeedPostProcess bool
MarkupSanitizerRules []MarkupSanitizerRule
}
// MarkupSanitizerRule defines the policy for whitelisting attributes on
// certain elements.
type MarkupSanitizerRule struct {
Element string
AllowAttr string
Regexp *regexp.Regexp
Element string
AllowAttr string
Regexp *regexp.Regexp
AllowDataURIImages bool
}
func newMarkup() {
ExternalMarkupRenderers = make([]MarkupRenderer, 0, 10)
ExternalMarkupRenderers = make([]*MarkupRenderer, 0, 10)
ExternalSanitizerRules = make([]MarkupSanitizerRule, 0, 10)
for _, sec := range Cfg.Section("markup").ChildSections() {
name := strings.TrimPrefix(sec.Name(), "markup.")
if name == "" {
@ -56,50 +59,62 @@ func newMarkup() {
}
func newMarkupSanitizer(name string, sec *ini.Section) {
haveElement := sec.HasKey("ELEMENT")
haveAttr := sec.HasKey("ALLOW_ATTR")
haveRegexp := sec.HasKey("REGEXP")
if !haveElement && !haveAttr && !haveRegexp {
log.Warn("Skipping empty section: markup.%s.", name)
return
rule, ok := createMarkupSanitizerRule(name, sec)
if ok {
if strings.HasPrefix(name, "sanitizer.") {
names := strings.SplitN(strings.TrimPrefix(name, "sanitizer."), ".", 2)
name = names[0]
}
for _, renderer := range ExternalMarkupRenderers {
if name == renderer.MarkupName {
renderer.MarkupSanitizerRules = append(renderer.MarkupSanitizerRules, rule)
return
}
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
}
}
if !haveElement || !haveAttr || !haveRegexp {
log.Error("Missing required keys from markup.%s. Must have all three of ELEMENT, ALLOW_ATTR, and REGEXP defined!", name)
return
func createMarkupSanitizerRule(name string, sec *ini.Section) (MarkupSanitizerRule, bool) {
var rule MarkupSanitizerRule
ok := false
if sec.HasKey("ALLOW_DATA_URI_IMAGES") {
rule.AllowDataURIImages = sec.Key("ALLOW_DATA_URI_IMAGES").MustBool(false)
ok = true
}
elements := sec.Key("ELEMENT").Value()
allowAttrs := sec.Key("ALLOW_ATTR").Value()
regexpStr := sec.Key("REGEXP").Value()
if sec.HasKey("ELEMENT") || sec.HasKey("ALLOW_ATTR") {
rule.Element = sec.Key("ELEMENT").Value()
rule.AllowAttr = sec.Key("ALLOW_ATTR").Value()
if regexpStr == "" {
rule := MarkupSanitizerRule{
Element: elements,
AllowAttr: allowAttrs,
Regexp: nil,
if rule.Element == "" || rule.AllowAttr == "" {
log.Error("Missing required values from markup.%s. Must have ELEMENT and ALLOW_ATTR defined!", name)
return rule, false
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
return
}
regexpStr := sec.Key("REGEXP").Value()
if regexpStr != "" {
// Validate when parsing the config that this is a valid regular
// expression. Then we can use regexp.MustCompile(...) later.
compiled, err := regexp.Compile(regexpStr)
if err != nil {
log.Error("In markup.%s: REGEXP (%s) failed to compile: %v", name, regexpStr, err)
return rule, false
}
rule.Regexp = compiled
}
// Validate when parsing the config that this is a valid regular
// expression. Then we can use regexp.MustCompile(...) later.
compiled, err := regexp.Compile(regexpStr)
if err != nil {
log.Error("In module.%s: REGEXP (%s) at definition %d failed to compile: %v", regexpStr, name, err)
return
ok = true
}
rule := MarkupSanitizerRule{
Element: elements,
AllowAttr: allowAttrs,
Regexp: compiled,
if !ok {
log.Error("Missing required keys from markup.%s. Must have ELEMENT and ALLOW_ATTR or ALLOW_DATA_URI_IMAGES defined!", name)
return rule, false
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
return rule, true
}
func newMarkupRenderer(name string, sec *ini.Section) {
@ -126,7 +141,7 @@ func newMarkupRenderer(name string, sec *ini.Section) {
return
}
ExternalMarkupRenderers = append(ExternalMarkupRenderers, MarkupRenderer{
ExternalMarkupRenderers = append(ExternalMarkupRenderers, &MarkupRenderer{
Enabled: sec.Key("ENABLED").MustBool(false),
MarkupName: name,
FileExtensions: exts,

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