mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-11-01 13:01:15 +00:00
bb448f3dc2
- Fixes an XSS that was introduced in https://codeberg.org/forgejo/forgejo/pulls/1433 - This XSS allows for `href`s in anchor elements to be set to a `javascript:` uri in the repository description, which would upon clicking (and not upon loading) the anchor element execute the specified javascript in that uri. - [`AllowStandardURLs`](https://pkg.go.dev/github.com/microcosm-cc/bluemonday#Policy.AllowStandardURLs) is now called for the repository description policy, which ensures that URIs in anchor elements are `mailto:`, `http://` or `https://` and thereby disallowing the `javascript:` URI. It also now allows non-relative links and sets `rel="nofollow"` on anchor elements. - Unit test added.
236 lines
9.2 KiB
Go
236 lines
9.2 KiB
Go
// Copyright 2017 The Gitea Authors. All rights reserved.
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// Copyright 2017 The Gogs Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package markup
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import (
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"io"
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"net/url"
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"regexp"
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"sync"
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"code.gitea.io/gitea/modules/setting"
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"github.com/microcosm-cc/bluemonday"
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)
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// Sanitizer is a protection wrapper of *bluemonday.Policy which does not allow
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// any modification to the underlying policies once it's been created.
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type Sanitizer struct {
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defaultPolicy *bluemonday.Policy
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descriptionPolicy *bluemonday.Policy
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rendererPolicies map[string]*bluemonday.Policy
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init sync.Once
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}
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var (
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sanitizer = &Sanitizer{}
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allowAllRegex = regexp.MustCompile(".+")
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)
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// NewSanitizer initializes sanitizer with allowed attributes based on settings.
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// Multiple calls to this function will only create one instance of Sanitizer during
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// entire application lifecycle.
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func NewSanitizer() {
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sanitizer.init.Do(func() {
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InitializeSanitizer()
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})
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}
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// InitializeSanitizer (re)initializes the current sanitizer to account for changes in settings
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func InitializeSanitizer() {
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sanitizer.rendererPolicies = map[string]*bluemonday.Policy{}
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sanitizer.defaultPolicy = createDefaultPolicy()
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sanitizer.descriptionPolicy = createRepoDescriptionPolicy()
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for name, renderer := range renderers {
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sanitizerRules := renderer.SanitizerRules()
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if len(sanitizerRules) > 0 {
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policy := createDefaultPolicy()
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addSanitizerRules(policy, sanitizerRules)
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sanitizer.rendererPolicies[name] = policy
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}
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}
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}
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func createDefaultPolicy() *bluemonday.Policy {
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policy := bluemonday.UGCPolicy()
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// For JS code copy and Mermaid loading state
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^code-block( is-loading)?$`)).OnElements("pre")
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// For color preview
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^color-preview$`)).OnElements("span")
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// For attention
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-title$`)).OnElements("p")
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-header attention-\w+$`)).OnElements("blockquote")
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-\w+$`)).OnElements("strong")
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-icon attention-\w+ svg octicon-[\w-]+$`)).OnElements("svg")
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policy.AllowAttrs("viewBox", "width", "height", "aria-hidden").OnElements("svg")
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policy.AllowAttrs("fill-rule", "d").OnElements("path")
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// For Chroma markdown plugin
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(chroma )?language-[\w-]+( display)?( is-loading)?$`)).OnElements("code")
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// Checkboxes
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policy.AllowAttrs("type").Matching(regexp.MustCompile(`^checkbox$`)).OnElements("input")
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policy.AllowAttrs("checked", "disabled", "data-source-position").OnElements("input")
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// Custom URL-Schemes
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if len(setting.Markdown.CustomURLSchemes) > 0 {
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policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
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} else {
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policy.AllowURLSchemesMatching(allowAllRegex)
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// Even if every scheme is allowed, these three are blocked for security reasons
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disallowScheme := func(*url.URL) bool {
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return false
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}
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policy.AllowURLSchemeWithCustomPolicy("javascript", disallowScheme)
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policy.AllowURLSchemeWithCustomPolicy("vbscript", disallowScheme)
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policy.AllowURLSchemeWithCustomPolicy("data", disallowScheme)
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}
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// Allow classes for anchors
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`ref-issue( ref-external-issue)?`)).OnElements("a")
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// Allow classes for task lists
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`task-list-item`)).OnElements("li")
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// Allow classes for org mode list item status.
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(unchecked|checked|indeterminate)$`)).OnElements("li")
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// Allow icons
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^icon(\s+[\p{L}\p{N}_-]+)+$`)).OnElements("i")
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// Allow classes for emojis
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`emoji`)).OnElements("img")
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// Allow icons, emojis, chroma syntax and keyword markup on span
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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 + `$`)).OnElements("span")
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// Allow 'color' and 'background-color' properties for the style attribute on text elements and table cells.
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policy.AllowStyles("color", "background-color").OnElements("span", "p", "th", "td")
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// Allow classes for file preview links...
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^(lines-num|lines-code chroma)$")).OnElements("td")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^code-inner$")).OnElements("code")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^file-preview-box$")).OnElements("div")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^ui table$")).OnElements("div")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^header$")).OnElements("div")
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policy.AllowAttrs("data-line-number").Matching(regexp.MustCompile("^[0-9]+$")).OnElements("span")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^text small grey$")).OnElements("span")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^file-preview*")).OnElements("table")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^lines-escape$")).OnElements("td")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^toggle-escape-button btn interact-bg$")).OnElements("button")
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policy.AllowAttrs("title").OnElements("button")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^ambiguous-code-point$")).OnElements("span")
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policy.AllowAttrs("data-tooltip-content").OnElements("span")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("muted|(text black)")).OnElements("a")
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policy.AllowAttrs("class").Matching(regexp.MustCompile("^ui warning message tw-text-left$")).OnElements("div")
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// Allow generally safe attributes
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generalSafeAttrs := []string{
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"abbr", "accept", "accept-charset",
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"accesskey", "action", "align", "alt",
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"aria-describedby", "aria-hidden", "aria-label", "aria-labelledby",
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"axis", "border", "cellpadding", "cellspacing", "char",
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"charoff", "charset", "checked",
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"clear", "cols", "colspan", "color",
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"compact", "coords", "datetime", "dir",
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"disabled", "enctype", "for", "frame",
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"headers", "height", "hreflang",
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"hspace", "ismap", "label", "lang",
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"maxlength", "media", "method",
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"multiple", "name", "nohref", "noshade",
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"nowrap", "open", "prompt", "readonly", "rel", "rev",
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"rows", "rowspan", "rules", "scope",
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"selected", "shape", "size", "span",
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"start", "summary", "tabindex", "target",
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"title", "type", "usemap", "valign", "value",
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"vspace", "width", "itemprop",
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}
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generalSafeElements := []string{
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"h1", "h2", "h3", "h4", "h5", "h6", "h7", "h8", "br", "b", "i", "strong", "em", "a", "pre", "code", "img", "tt",
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"div", "ins", "del", "sup", "sub", "p", "ol", "ul", "table", "thead", "tbody", "tfoot", "blockquote", "label",
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"dl", "dt", "dd", "kbd", "q", "samp", "var", "hr", "ruby", "rt", "rp", "li", "tr", "td", "th", "s", "strike", "summary",
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"details", "caption", "figure", "figcaption",
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"abbr", "bdo", "cite", "dfn", "mark", "small", "span", "time", "video", "wbr",
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}
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policy.AllowAttrs(generalSafeAttrs...).OnElements(generalSafeElements...)
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policy.AllowAttrs("src", "autoplay", "controls").OnElements("video")
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policy.AllowAttrs("itemscope", "itemtype").OnElements("div")
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// FIXME: Need to handle longdesc in img but there is no easy way to do it
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// Custom keyword markup
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addSanitizerRules(policy, setting.ExternalSanitizerRules)
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return policy
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}
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// createRepoDescriptionPolicy returns a minimal more strict policy that is used for
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// repository descriptions.
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func createRepoDescriptionPolicy() *bluemonday.Policy {
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policy := bluemonday.NewPolicy()
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policy.AllowStandardURLs()
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// Allow italics and bold.
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policy.AllowElements("i", "b", "em", "strong")
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// Allow code.
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policy.AllowElements("code")
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// Allow links
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policy.AllowAttrs("href", "target", "rel").OnElements("a")
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// Allow classes for emojis
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policy.AllowAttrs("class").Matching(regexp.MustCompile(`^emoji$`)).OnElements("img", "span")
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policy.AllowAttrs("aria-label").OnElements("span")
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return policy
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}
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func addSanitizerRules(policy *bluemonday.Policy, rules []setting.MarkupSanitizerRule) {
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for _, rule := range rules {
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if rule.AllowDataURIImages {
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policy.AllowDataURIImages()
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}
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if rule.Element != "" {
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if rule.Regexp != nil {
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policy.AllowAttrs(rule.AllowAttr).Matching(rule.Regexp).OnElements(rule.Element)
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} else {
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policy.AllowAttrs(rule.AllowAttr).OnElements(rule.Element)
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}
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}
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}
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}
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// SanitizeDescription sanitizes the HTML generated for a repository description.
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func SanitizeDescription(s string) string {
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NewSanitizer()
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return sanitizer.descriptionPolicy.Sanitize(s)
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}
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// Sanitize takes a string that contains a HTML fragment or document and applies policy whitelist.
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func Sanitize(s string) string {
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NewSanitizer()
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return sanitizer.defaultPolicy.Sanitize(s)
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}
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// SanitizeReader sanitizes a Reader
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func SanitizeReader(r io.Reader, renderer string, w io.Writer) error {
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NewSanitizer()
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policy, exist := sanitizer.rendererPolicies[renderer]
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if !exist {
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policy = sanitizer.defaultPolicy
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}
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return policy.SanitizeReaderToWriter(r, w)
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}
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