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forgejo/modules/markup/sanitizer.go
Giteabot f8a40dafb9
Allow <video> in MarkDown () ()
Backport 

As you can imagine, for the Blender development process it is rather
nice to be able to include videos in issues, pull requests, etc.

This PR allows the `<video>` HTML tag to be used in MarkDown, with the
`src`, `autoplay`, and `controls` attributes.

## Help Needed

To have this fully functional, personally I feel the following things
are still missing, and would appreciate some help from the Gitea team.

### Styling

Some CSS is needed, but I couldn't figure out which of the LESS files
would work. I tried `web_src/less/markup/content.less` and
`web_src/less/_base.less`, but after running `make` the changes weren't
seen in the frontend.

This I would consider a minimal set of CSS rules to be applied:

```css
video {
  max-width: 100%;
  max-height: 100vh;
}
```

### Default Attributes

It would be fantastic if Gitea could add some default attributes to the
`<video>` tag. Basically `controls` should always be there, as there is
no point in disallowing scrolling through videos, looping them, etc.

### Integration with the attachments system

Another thing that could be added, but probably should be done in a
separate PR, is the integration with the attachments system. Dragging in
a video should attach it, then generate the appropriate MarkDown/HTML.

Co-authored-by: Sybren <122987084+drsybren@users.noreply.github.com>
2023-03-02 11:49:05 -05:00

176 lines
6.3 KiB
Go

// Copyright 2017 The Gitea Authors. All rights reserved.
// Copyright 2017 The Gogs Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package markup
import (
"io"
"regexp"
"sync"
"code.gitea.io/gitea/modules/setting"
"github.com/microcosm-cc/bluemonday"
)
// 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 {
defaultPolicy *bluemonday.Policy
rendererPolicies map[string]*bluemonday.Policy
init sync.Once
}
var sanitizer = &Sanitizer{}
// NewSanitizer initializes sanitizer with allowed attributes based on settings.
// Multiple calls to this function will only create one instance of Sanitizer during
// entire application lifecycle.
func NewSanitizer() {
sanitizer.init.Do(func() {
InitializeSanitizer()
})
}
// 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 JS code copy and Mermaid loading state
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^code-block( is-loading)?$`)).OnElements("pre")
// For color preview
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^color-preview$`)).OnElements("span")
// For attention
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-\w+$`)).OnElements("strong")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-icon attention-\w+$`)).OnElements("span", "strong")
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^svg octicon-\w+$`)).OnElements("svg")
policy.AllowAttrs("viewBox", "width", "height", "aria-hidden").OnElements("svg")
policy.AllowAttrs("fill-rule", "d").OnElements("path")
// For Chroma markdown plugin
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(chroma )?language-[\w-]+( display)?( is-loading)?$`)).OnElements("code")
// Checkboxes
policy.AllowAttrs("type").Matching(regexp.MustCompile(`^checkbox$`)).OnElements("input")
policy.AllowAttrs("checked", "disabled", "data-source-position").OnElements("input")
// Custom URL-Schemes
if len(setting.Markdown.CustomURLSchemes) > 0 {
policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
}
// Allow classes for anchors
policy.AllowAttrs("class").Matching(regexp.MustCompile(`ref-issue( ref-external-issue)?`)).OnElements("a")
// Allow classes for task lists
policy.AllowAttrs("class").Matching(regexp.MustCompile(`task-list-item`)).OnElements("li")
// Allow icons
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^icon(\s+[\p{L}\p{N}_-]+)+$`)).OnElements("i")
// Allow unlabelled labels
policy.AllowNoAttrs().OnElements("label")
// Allow classes for emojis
policy.AllowAttrs("class").Matching(regexp.MustCompile(`emoji`)).OnElements("img")
// Allow icons, emojis, chroma syntax and keyword markup on span
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^((icon(\s+[\p{L}\p{N}_-]+)+)|(emoji)|(language-math display)|(language-math inline))$|^([a-z][a-z0-9]{0,2})$|^` + keywordClass + `$`)).OnElements("span")
// Allow 'style' attribute on text elements.
policy.AllowAttrs("style").OnElements("span", "p")
// Allow 'color' and 'background-color' properties for the style attribute on text elements.
policy.AllowStyles("color", "background-color").OnElements("span", "p")
// Allow generally safe attributes
generalSafeAttrs := []string{
"abbr", "accept", "accept-charset",
"accesskey", "action", "align", "alt",
"aria-describedby", "aria-hidden", "aria-label", "aria-labelledby",
"axis", "border", "cellpadding", "cellspacing", "char",
"charoff", "charset", "checked",
"clear", "cols", "colspan", "color",
"compact", "coords", "datetime", "dir",
"disabled", "enctype", "for", "frame",
"headers", "height", "hreflang",
"hspace", "ismap", "label", "lang",
"maxlength", "media", "method",
"multiple", "name", "nohref", "noshade",
"nowrap", "open", "prompt", "readonly", "rel", "rev",
"rows", "rowspan", "rules", "scope",
"selected", "shape", "size", "span",
"start", "summary", "tabindex", "target",
"title", "type", "usemap", "valign", "value",
"vspace", "width", "itemprop",
}
generalSafeElements := []string{
"h1", "h2", "h3", "h4", "h5", "h6", "h7", "h8", "br", "b", "i", "strong", "em", "a", "pre", "code", "img", "tt",
"div", "ins", "del", "sup", "sub", "p", "ol", "ul", "table", "thead", "tbody", "tfoot", "blockquote",
"dl", "dt", "dd", "kbd", "q", "samp", "var", "hr", "ruby", "rt", "rp", "li", "tr", "td", "th", "s", "strike", "summary",
"details", "caption", "figure", "figcaption",
"abbr", "bdo", "cite", "dfn", "mark", "small", "span", "time", "wbr",
}
policy.AllowAttrs(generalSafeAttrs...).OnElements(generalSafeElements...)
policy.AllowAttrs("src", "autoplay", "controls").OnElements("video")
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
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)
}
}
}
}
// Sanitize takes a string that contains a HTML fragment or document and applies policy whitelist.
func Sanitize(s string) string {
NewSanitizer()
return sanitizer.defaultPolicy.Sanitize(s)
}
// SanitizeReader sanitizes a Reader
func SanitizeReader(r io.Reader, renderer string, w io.Writer) error {
NewSanitizer()
policy, exist := sanitizer.rendererPolicies[renderer]
if !exist {
policy = sanitizer.defaultPolicy
}
return policy.SanitizeReaderToWriter(r, w)
}