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Diffstat (limited to 'src/http/static/viz/2/goog/html/safestyle.js')
| -rw-r--r-- | src/http/static/viz/2/goog/html/safestyle.js | 560 |
1 files changed, 560 insertions, 0 deletions
diff --git a/src/http/static/viz/2/goog/html/safestyle.js b/src/http/static/viz/2/goog/html/safestyle.js new file mode 100644 index 0000000..506a475 --- /dev/null +++ b/src/http/static/viz/2/goog/html/safestyle.js @@ -0,0 +1,560 @@ +// Copyright 2014 The Closure Library Authors. All Rights Reserved. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS-IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +/** + * @fileoverview The SafeStyle type and its builders. + * + * TODO(xtof): Link to document stating type contract. + */ + +goog.provide('goog.html.SafeStyle'); + +goog.require('goog.array'); +goog.require('goog.asserts'); +goog.require('goog.html.SafeUrl'); +goog.require('goog.string'); +goog.require('goog.string.Const'); +goog.require('goog.string.TypedString'); + + + +/** + * A string-like object which represents a sequence of CSS declarations + * ({@code propertyName1: propertyvalue1; propertyName2: propertyValue2; ...}) + * and that carries the security type contract that its value, as a string, + * will not cause untrusted script execution (XSS) when evaluated as CSS in a + * browser. + * + * Instances of this type must be created via the factory methods + * ({@code goog.html.SafeStyle.create} or + * {@code goog.html.SafeStyle.fromConstant}) and not by invoking its + * constructor. The constructor intentionally takes no parameters and the type + * is immutable; hence only a default instance corresponding to the empty string + * can be obtained via constructor invocation. + * + * SafeStyle's string representation can safely be: + * <ul> + * <li>Interpolated as the content of a *quoted* HTML style attribute. + * However, the SafeStyle string *must be HTML-attribute-escaped* before + * interpolation. + * <li>Interpolated as the content of a {}-wrapped block within a stylesheet. + * '<' characters in the SafeStyle string *must be CSS-escaped* before + * interpolation. The SafeStyle string is also guaranteed not to be able + * to introduce new properties or elide existing ones. + * <li>Interpolated as the content of a {}-wrapped block within an HTML + * <style> element. '<' characters in the SafeStyle string + * *must be CSS-escaped* before interpolation. + * <li>Assigned to the style property of a DOM node. The SafeStyle string + * should not be escaped before being assigned to the property. + * </ul> + * + * A SafeStyle may never contain literal angle brackets. Otherwise, it could + * be unsafe to place a SafeStyle into a <style> tag (where it can't + * be HTML escaped). For example, if the SafeStyle containing + * "{@code font: 'foo <style/><script>evil</script>'}" were + * interpolated within a <style> tag, this would then break out of the + * style context into HTML. + * + * A SafeStyle may contain literal single or double quotes, and as such the + * entire style string must be escaped when used in a style attribute (if + * this were not the case, the string could contain a matching quote that + * would escape from the style attribute). + * + * Values of this type must be composable, i.e. for any two values + * {@code style1} and {@code style2} of this type, + * {@code goog.html.SafeStyle.unwrap(style1) + + * goog.html.SafeStyle.unwrap(style2)} must itself be a value that satisfies + * the SafeStyle type constraint. This requirement implies that for any value + * {@code style} of this type, {@code goog.html.SafeStyle.unwrap(style)} must + * not end in a "property value" or "property name" context. For example, + * a value of {@code background:url("} or {@code font-} would not satisfy the + * SafeStyle contract. This is because concatenating such strings with a + * second value that itself does not contain unsafe CSS can result in an + * overall string that does. For example, if {@code javascript:evil())"} is + * appended to {@code background:url("}, the resulting string may result in + * the execution of a malicious script. + * + * TODO(mlourenco): Consider whether we should implement UTF-8 interchange + * validity checks and blacklisting of newlines (including Unicode ones) and + * other whitespace characters (\t, \f). Document here if so and also update + * SafeStyle.fromConstant(). + * + * The following example values comply with this type's contract: + * <ul> + * <li><pre>width: 1em;</pre> + * <li><pre>height:1em;</pre> + * <li><pre>width: 1em;height: 1em;</pre> + * <li><pre>background:url('http://url');</pre> + * </ul> + * In addition, the empty string is safe for use in a CSS attribute. + * + * The following example values do NOT comply with this type's contract: + * <ul> + * <li><pre>background: red</pre> (missing a trailing semi-colon) + * <li><pre>background:</pre> (missing a value and a trailing semi-colon) + * <li><pre>1em</pre> (missing an attribute name, which provides context for + * the value) + * </ul> + * + * @see goog.html.SafeStyle#create + * @see goog.html.SafeStyle#fromConstant + * @see http://www.w3.org/TR/css3-syntax/ + * @constructor + * @final + * @struct + * @implements {goog.string.TypedString} + */ +goog.html.SafeStyle = function() { + /** + * The contained value of this SafeStyle. The field has a purposely + * ugly name to make (non-compiled) code that attempts to directly access this + * field stand out. + * @private {string} + */ + this.privateDoNotAccessOrElseSafeStyleWrappedValue_ = ''; + + /** + * A type marker used to implement additional run-time type checking. + * @see goog.html.SafeStyle#unwrap + * @const {!Object} + * @private + */ + this.SAFE_STYLE_TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ = + goog.html.SafeStyle.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_; +}; + + +/** + * @override + * @const + */ +goog.html.SafeStyle.prototype.implementsGoogStringTypedString = true; + + +/** + * Type marker for the SafeStyle type, used to implement additional + * run-time type checking. + * @const {!Object} + * @private + */ +goog.html.SafeStyle.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ = {}; + + +/** + * Creates a SafeStyle object from a compile-time constant string. + * + * {@code style} should be in the format + * {@code name: value; [name: value; ...]} and must not have any < or > + * characters in it. This is so that SafeStyle's contract is preserved, + * allowing the SafeStyle to correctly be interpreted as a sequence of CSS + * declarations and without affecting the syntactic structure of any + * surrounding CSS and HTML. + * + * This method performs basic sanity checks on the format of {@code style} + * but does not constrain the format of {@code name} and {@code value}, except + * for disallowing tag characters. + * + * @param {!goog.string.Const} style A compile-time-constant string from which + * to create a SafeStyle. + * @return {!goog.html.SafeStyle} A SafeStyle object initialized to + * {@code style}. + */ +goog.html.SafeStyle.fromConstant = function(style) { + var styleString = goog.string.Const.unwrap(style); + if (styleString.length === 0) { + return goog.html.SafeStyle.EMPTY; + } + goog.html.SafeStyle.checkStyle_(styleString); + goog.asserts.assert( + goog.string.endsWith(styleString, ';'), + 'Last character of style string is not \';\': ' + styleString); + goog.asserts.assert( + goog.string.contains(styleString, ':'), + 'Style string must contain at least one \':\', to ' + + 'specify a "name: value" pair: ' + styleString); + return goog.html.SafeStyle.createSafeStyleSecurityPrivateDoNotAccessOrElse( + styleString); +}; + + +/** + * Checks if the style definition is valid. + * @param {string} style + * @private + */ +goog.html.SafeStyle.checkStyle_ = function(style) { + goog.asserts.assert( + !/[<>]/.test(style), 'Forbidden characters in style string: ' + style); +}; + + +/** + * Returns this SafeStyle's value as a string. + * + * IMPORTANT: In code where it is security relevant that an object's type is + * indeed {@code SafeStyle}, use {@code goog.html.SafeStyle.unwrap} instead of + * this method. If in doubt, assume that it's security relevant. In particular, + * note that goog.html functions which return a goog.html type do not guarantee + * the returned instance is of the right type. For example: + * + * <pre> + * var fakeSafeHtml = new String('fake'); + * fakeSafeHtml.__proto__ = goog.html.SafeHtml.prototype; + * var newSafeHtml = goog.html.SafeHtml.htmlEscape(fakeSafeHtml); + * // newSafeHtml is just an alias for fakeSafeHtml, it's passed through by + * // goog.html.SafeHtml.htmlEscape() as fakeSafeHtml + * // instanceof goog.html.SafeHtml. + * </pre> + * + * @see goog.html.SafeStyle#unwrap + * @override + */ +goog.html.SafeStyle.prototype.getTypedStringValue = function() { + return this.privateDoNotAccessOrElseSafeStyleWrappedValue_; +}; + + +if (goog.DEBUG) { + /** + * Returns a debug string-representation of this value. + * + * To obtain the actual string value wrapped in a SafeStyle, use + * {@code goog.html.SafeStyle.unwrap}. + * + * @see goog.html.SafeStyle#unwrap + * @override + */ + goog.html.SafeStyle.prototype.toString = function() { + return 'SafeStyle{' + this.privateDoNotAccessOrElseSafeStyleWrappedValue_ + + '}'; + }; +} + + +/** + * Performs a runtime check that the provided object is indeed a + * SafeStyle object, and returns its value. + * + * @param {!goog.html.SafeStyle} safeStyle The object to extract from. + * @return {string} The safeStyle object's contained string, unless + * the run-time type check fails. In that case, {@code unwrap} returns an + * innocuous string, or, if assertions are enabled, throws + * {@code goog.asserts.AssertionError}. + */ +goog.html.SafeStyle.unwrap = function(safeStyle) { + // Perform additional Run-time type-checking to ensure that + // safeStyle is indeed an instance of the expected type. This + // provides some additional protection against security bugs due to + // application code that disables type checks. + // Specifically, the following checks are performed: + // 1. The object is an instance of the expected type. + // 2. The object is not an instance of a subclass. + // 3. The object carries a type marker for the expected type. "Faking" an + // object requires a reference to the type marker, which has names intended + // to stand out in code reviews. + if (safeStyle instanceof goog.html.SafeStyle && + safeStyle.constructor === goog.html.SafeStyle && + safeStyle.SAFE_STYLE_TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ === + goog.html.SafeStyle.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_) { + return safeStyle.privateDoNotAccessOrElseSafeStyleWrappedValue_; + } else { + goog.asserts.fail('expected object of type SafeStyle, got \'' + + safeStyle + '\' of type ' + goog.typeOf(safeStyle)); + return 'type_error:SafeStyle'; + } +}; + + +/** + * Package-internal utility method to create SafeStyle instances. + * + * @param {string} style The string to initialize the SafeStyle object with. + * @return {!goog.html.SafeStyle} The initialized SafeStyle object. + * @package + */ +goog.html.SafeStyle.createSafeStyleSecurityPrivateDoNotAccessOrElse = function( + style) { + return new goog.html.SafeStyle().initSecurityPrivateDoNotAccessOrElse_(style); +}; + + +/** + * Called from createSafeStyleSecurityPrivateDoNotAccessOrElse(). This + * method exists only so that the compiler can dead code eliminate static + * fields (like EMPTY) when they're not accessed. + * @param {string} style + * @return {!goog.html.SafeStyle} + * @private + */ +goog.html.SafeStyle.prototype.initSecurityPrivateDoNotAccessOrElse_ = function( + style) { + this.privateDoNotAccessOrElseSafeStyleWrappedValue_ = style; + return this; +}; + + +/** + * A SafeStyle instance corresponding to the empty string. + * @const {!goog.html.SafeStyle} + */ +goog.html.SafeStyle.EMPTY = + goog.html.SafeStyle.createSafeStyleSecurityPrivateDoNotAccessOrElse(''); + + +/** + * The innocuous string generated by goog.html.SafeStyle.create when passed + * an unsafe value. + * @const {string} + */ +goog.html.SafeStyle.INNOCUOUS_STRING = 'zClosurez'; + + +/** + * A single property value. + * @typedef {string|!goog.string.Const|!goog.html.SafeUrl} + */ +goog.html.SafeStyle.PropertyValue; + + +/** + * Mapping of property names to their values. + * We don't support numbers even though some values might be numbers (e.g. + * line-height or 0 for any length). The reason is that most numeric values need + * units (e.g. '1px') and allowing numbers could cause users forgetting about + * them. + * @typedef {!Object<string, ?goog.html.SafeStyle.PropertyValue| + * ?Array<!goog.html.SafeStyle.PropertyValue>>} + */ +goog.html.SafeStyle.PropertyMap; + + +/** + * Creates a new SafeStyle object from the properties specified in the map. + * @param {goog.html.SafeStyle.PropertyMap} map Mapping of property names to + * their values, for example {'margin': '1px'}. Names must consist of + * [-_a-zA-Z0-9]. Values might be strings consisting of + * [-,.'"%_!# a-zA-Z0-9], where " and ' must be properly balanced. We also + * allow simple functions like rgb() and url() which sanitizes its contents. + * Other values must be wrapped in goog.string.Const. URLs might be passed + * as goog.html.SafeUrl which will be wrapped into url(""). We also support + * array whose elements are joined with ' '. Null value causes skipping the + * property. + * @return {!goog.html.SafeStyle} + * @throws {Error} If invalid name is provided. + * @throws {goog.asserts.AssertionError} If invalid value is provided. With + * disabled assertions, invalid value is replaced by + * goog.html.SafeStyle.INNOCUOUS_STRING. + */ +goog.html.SafeStyle.create = function(map) { + var style = ''; + for (var name in map) { + if (!/^[-_a-zA-Z0-9]+$/.test(name)) { + throw Error('Name allows only [-_a-zA-Z0-9], got: ' + name); + } + var value = map[name]; + if (value == null) { + continue; + } + if (goog.isArray(value)) { + value = goog.array.map(value, goog.html.SafeStyle.sanitizePropertyValue_) + .join(' '); + } else { + value = goog.html.SafeStyle.sanitizePropertyValue_(value); + } + style += name + ':' + value + ';'; + } + if (!style) { + return goog.html.SafeStyle.EMPTY; + } + goog.html.SafeStyle.checkStyle_(style); + return goog.html.SafeStyle.createSafeStyleSecurityPrivateDoNotAccessOrElse( + style); +}; + + +/** + * Checks and converts value to string. + * @param {!goog.html.SafeStyle.PropertyValue} value + * @return {string} + * @private + */ +goog.html.SafeStyle.sanitizePropertyValue_ = function(value) { + if (value instanceof goog.html.SafeUrl) { + var url = goog.html.SafeUrl.unwrap(value); + return 'url("' + url.replace(/</g, '%3c').replace(/[\\"]/g, '\\$&') + '")'; + } + var result = value instanceof goog.string.Const ? + goog.string.Const.unwrap(value) : + goog.html.SafeStyle.sanitizePropertyValueString_(String(value)); + // These characters can be used to change context and we don't want that even + // with const values. + goog.asserts.assert(!/[{;}]/.test(result), 'Value does not allow [{;}].'); + return result; +}; + + +/** + * Checks string value. + * @param {string} value + * @return {string} + * @private + */ +goog.html.SafeStyle.sanitizePropertyValueString_ = function(value) { + var valueWithoutFunctions = + value.replace(goog.html.SafeUrl.FUNCTIONS_RE_, '$1') + .replace(goog.html.SafeUrl.URL_RE_, 'url'); + if (!goog.html.SafeStyle.VALUE_RE_.test(valueWithoutFunctions)) { + goog.asserts.fail( + 'String value allows only ' + goog.html.SafeStyle.VALUE_ALLOWED_CHARS_ + + ' and simple functions, got: ' + value); + return goog.html.SafeStyle.INNOCUOUS_STRING; + } else if (!goog.html.SafeStyle.hasBalancedQuotes_(value)) { + goog.asserts.fail('String value requires balanced quotes, got: ' + value); + return goog.html.SafeStyle.INNOCUOUS_STRING; + } + return goog.html.SafeStyle.sanitizeUrl_(value); +}; + + +/** + * Checks that quotes (" and ') are properly balanced inside a string. Assumes + * that neither escape (\) nor any other character that could result in + * breaking out of a string parsing context are allowed; + * see http://www.w3.org/TR/css3-syntax/#string-token-diagram. + * @param {string} value Untrusted CSS property value. + * @return {boolean} True if property value is safe with respect to quote + * balancedness. + * @private + */ +goog.html.SafeStyle.hasBalancedQuotes_ = function(value) { + var outsideSingle = true; + var outsideDouble = true; + for (var i = 0; i < value.length; i++) { + var c = value.charAt(i); + if (c == "'" && outsideDouble) { + outsideSingle = !outsideSingle; + } else if (c == '"' && outsideSingle) { + outsideDouble = !outsideDouble; + } + } + return outsideSingle && outsideDouble; +}; + + +/** + * Characters allowed in goog.html.SafeStyle.VALUE_RE_. + * @private {string} + */ +goog.html.SafeStyle.VALUE_ALLOWED_CHARS_ = '[-,."\'%_!# a-zA-Z0-9]'; + + +/** + * Regular expression for safe values. + * + * Quotes (" and ') are allowed, but a check must be done elsewhere to ensure + * they're balanced. + * + * ',' allows multiple values to be assigned to the same property + * (e.g. background-attachment or font-family) and hence could allow + * multiple values to get injected, but that should pose no risk of XSS. + * + * The expression checks only for XSS safety, not for CSS validity. + * @const {!RegExp} + * @private + */ +goog.html.SafeStyle.VALUE_RE_ = + new RegExp('^' + goog.html.SafeStyle.VALUE_ALLOWED_CHARS_ + '+$'); + + +/** + * Regular expression for url(). We support URLs allowed by + * https://www.w3.org/TR/css-syntax-3/#url-token-diagram without using escape + * sequences. Use percent-encoding if you need to use special characters like + * backslash. + * @private @const {!RegExp} + */ +goog.html.SafeUrl.URL_RE_ = new RegExp( + '\\b(url\\([ \t\n]*)(' + + '\'[ -&(-\\[\\]-~]*\'' + // Printable characters except ' and \. + '|"[ !#-\\[\\]-~]*"' + // Printable characters except " and \. + '|[!#-&*-\\[\\]-~]*' + // Printable characters except [ "'()\\]. + ')([ \t\n]*\\))', + 'g'); + + +/** + * Regular expression for simple functions. + * @private @const {!RegExp} + */ +goog.html.SafeUrl.FUNCTIONS_RE_ = new RegExp( + '\\b(hsl|hsla|rgb|rgba|(rotate|scale|translate)(X|Y|Z|3d)?)' + + '\\([-0-9a-z.%, ]+\\)', + 'g'); + + +/** + * Sanitize URLs inside url(). + * + * NOTE: We could also consider using CSS.escape once that's available in the + * browsers. However, loosely matching URL e.g. with url\(.*\) and then escaping + * the contents would result in a slightly different language than CSS leading + * to confusion of users. E.g. url(")") is valid in CSS but it would be invalid + * as seen by our parser. On the other hand, url(\) is invalid in CSS but our + * parser would be fine with it. + * + * @param {string} value Untrusted CSS property value. + * @return {string} + * @private + */ +goog.html.SafeStyle.sanitizeUrl_ = function(value) { + return value.replace( + goog.html.SafeUrl.URL_RE_, function(match, before, url, after) { + var quote = ''; + url = url.replace(/^(['"])(.*)\1$/, function(match, start, inside) { + quote = start; + return inside; + }); + var sanitized = goog.html.SafeUrl.sanitize(url).getTypedStringValue(); + return before + quote + sanitized + quote + after; + }); +}; + + +/** + * Creates a new SafeStyle object by concatenating the values. + * @param {...(!goog.html.SafeStyle|!Array<!goog.html.SafeStyle>)} var_args + * SafeStyles to concatenate. + * @return {!goog.html.SafeStyle} + */ +goog.html.SafeStyle.concat = function(var_args) { + var style = ''; + + /** + * @param {!goog.html.SafeStyle|!Array<!goog.html.SafeStyle>} argument + */ + var addArgument = function(argument) { + if (goog.isArray(argument)) { + goog.array.forEach(argument, addArgument); + } else { + style += goog.html.SafeStyle.unwrap(argument); + } + }; + + goog.array.forEach(arguments, addArgument); + if (!style) { + return goog.html.SafeStyle.EMPTY; + } + return goog.html.SafeStyle.createSafeStyleSecurityPrivateDoNotAccessOrElse( + style); +}; |