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forgejo/modules/markup/sanitizer.go
Earl Warren eaea530d6b
Render plaintext task list items for markdown files (#26186)
- The library that's being used for org-mode, [doesn't render the status
of list items](https://github.com/niklasfasching/go-org/issues/63).
- Add a modified version of the proposed CSS snippet to still display
the status for the list items. The alternative was parsing HTML and
transforming it, which is too complicated for this small task.
- Resolves https://codeberg.org/Codeberg/Community/issues/1099

(cherry picked from commit 9753c7e4b8)

Refs: https://codeberg.org/forgejo/forgejo/pulls/1071

Co-authored-by: Gusted <postmaster@gusted.xyz>
2023-07-27 14:15:31 +00:00

193 lines
6.9 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"
"net/url"
"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{}
allowAllRegex = regexp.MustCompile(".+")
)
// 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$`)).OnElements("input")
policy.AllowAttrs("checked", "disabled", "data-source-position").OnElements("input")
// Custom URL-Schemes
if len(setting.Markdown.CustomURLSchemes) > 0 {
policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
} else {
policy.AllowURLSchemesMatching(allowAllRegex)
// Even if every scheme is allowed, these three are blocked for security reasons
disallowScheme := func(*url.URL) bool {
return false
}
policy.AllowURLSchemeWithCustomPolicy("javascript", disallowScheme)
policy.AllowURLSchemeWithCustomPolicy("vbscript", disallowScheme)
policy.AllowURLSchemeWithCustomPolicy("data", disallowScheme)
}
// Allow classes for anchors
policy.AllowAttrs("class").Matching(regexp.MustCompile(`ref-issue( ref-external-issue)?`)).OnElements("a")
// Allow classes for task lists
policy.AllowAttrs("class").Matching(regexp.MustCompile(`task-list-item`)).OnElements("li")
// Allow classes for org mode list item status.
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(unchecked|checked|indeterminate)$`)).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", "video", "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)
}