// 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 descriptionPolicy *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() sanitizer.descriptionPolicy = createRepoDescriptionPolicy() 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(`^gt-py-3 attention attention-\w+$`)).OnElements("blockquote") policy.AllowAttrs("class").Matching(regexp.MustCompile(`^attention-\w+$`)).OnElements("strong") policy.AllowAttrs("class").Matching(regexp.MustCompile(`^gt-mr-2 gt-vm 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 + `$`)).OnElements("span") // Allow 'style' attribute on text elements. policy.AllowAttrs("style").OnElements("span", "p") // Allow 'color' and 'background-color' properties for the style attribute on text elements. policy.AllowStyles("color", "background-color").OnElements("span", "p") // Allow classes for file preview links... policy.AllowAttrs("class").Matching(regexp.MustCompile("^(lines-num|lines-code chroma)$")).OnElements("td") policy.AllowAttrs("class").Matching(regexp.MustCompile("^code-inner$")).OnElements("code") policy.AllowAttrs("class").Matching(regexp.MustCompile("^file-preview-box$")).OnElements("div") policy.AllowAttrs("class").Matching(regexp.MustCompile("^ui table$")).OnElements("div") policy.AllowAttrs("class").Matching(regexp.MustCompile("^header$")).OnElements("div") policy.AllowAttrs("data-line-number").Matching(regexp.MustCompile("^[0-9]+$")).OnElements("span") policy.AllowAttrs("class").Matching(regexp.MustCompile("^text small grey$")).OnElements("span") policy.AllowAttrs("rel").Matching(regexp.MustCompile("^L[0-9]+$")).OnElements("td") policy.AllowAttrs("class").Matching(regexp.MustCompile("^file-preview*")).OnElements("table") policy.AllowAttrs("class").Matching(regexp.MustCompile("^lines-escape$")).OnElements("td") policy.AllowAttrs("class").Matching(regexp.MustCompile("^toggle-escape-button btn interact-bg$")).OnElements("button") policy.AllowAttrs("title").OnElements("button") policy.AllowAttrs("class").Matching(regexp.MustCompile("^ambiguous-code-point$")).OnElements("span") policy.AllowAttrs("data-tooltip-content").OnElements("span") policy.AllowAttrs("class").Matching(regexp.MustCompile("muted|(text black)")).OnElements("a") // 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 } // createRepoDescriptionPolicy returns a minimal more strict policy that is used for // repository descriptions. func createRepoDescriptionPolicy() *bluemonday.Policy { policy := bluemonday.NewPolicy() // Allow italics and bold. policy.AllowElements("i", "b", "em", "strong") // Allow code. policy.AllowElements("code") // Allow links policy.AllowAttrs("href", "target", "rel").OnElements("a") // Allow classes for emojis policy.AllowAttrs("class").Matching(regexp.MustCompile(`^emoji$`)).OnElements("img", "span") policy.AllowAttrs("aria-label").OnElements("span") 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) } } } } // SanitizeDescription sanitizes the HTML generated for a repository description. func SanitizeDescription(s string) string { NewSanitizer() return sanitizer.descriptionPolicy.Sanitize(s) } // 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) }