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https://github.com/angular/angular
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908a102a87
Summary: This adds basic security hooks to Angular 2. * `SecurityContext` is a private API between core, compiler, and platform-browser. `SecurityContext` communicates what context a value is used in across template parser, compiler, and sanitization at runtime. * `SanitizationService` is the bare bones interface to sanitize values for a particular context. * `SchemaElementRegistry.securityContext(tagName, attributeOrPropertyName)` determines the security context for an attribute or property (it turns out attributes and properties match for the purposes of sanitization). Based on these hooks: * `DomSchemaElementRegistry` decides what sanitization applies in a particular context. * `DomSanitizationService` implements `SanitizationService` and adds *Safe Value*s, i.e. the ability to mark a value as safe and not requiring further sanitization. * `url_sanitizer` and `style_sanitizer` sanitize URLs and Styles, respectively (surprise!). `DomSanitizationService` is the default implementation bound for browser applications, in the three contexts (browser rendering, web worker rendering, server side rendering). BREAKING CHANGES: *** SECURITY WARNING *** Angular 2 Release Candidates do not implement proper contextual escaping yet. Make sure to correctly escape all values that go into the DOM. *** SECURITY WARNING *** Reviewers: IgorMinar Differential Revision: https://reviews.angular.io/D103
43 lines
1.5 KiB
TypeScript
43 lines
1.5 KiB
TypeScript
/**
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* Regular expression for safe style values.
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*
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* Quotes (" and ') are allowed, but a check must be done elsewhere to ensure
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* they're balanced.
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*
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* ',' allows multiple values to be assigned to the same property
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* (e.g. background-attachment or font-family) and hence could allow
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* multiple values to get injected, but that should pose no risk of XSS.
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*
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* The rgb() and rgba() expression checks only for XSS safety, not for CSS
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* validity.
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*
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* This regular expression was taken from the Closure sanitization library.
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*/
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const SAFE_STYLE_VALUE = /^([-,."'%_!# a-zA-Z0-9]+|(?:rgb|hsl)a?\([0-9.%, ]+\))$/;
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/**
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* Checks that quotes (" and ') are properly balanced inside a string. Assumes
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* that neither escape (\) nor any other character that could result in
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* breaking out of a string parsing context are allowed;
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* see http://www.w3.org/TR/css3-syntax/#string-token-diagram.
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*
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* This code was taken from the Closure sanitization library.
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*/
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function hasBalancedQuotes(value: string) {
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let outsideSingle = true;
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let outsideDouble = true;
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for (let i = 0; i < value.length; i++) {
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let c = value.charAt(i);
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if (c === '\'' && outsideDouble) {
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outsideSingle = !outsideSingle;
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} else if (c === '"' && outsideSingle) {
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outsideDouble = !outsideDouble;
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}
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}
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return outsideSingle && outsideDouble;
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}
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export function sanitizeStyle(value: string): string {
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if (String(value).match(SAFE_STYLE_VALUE) && hasBalancedQuotes(value)) return value;
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return 'unsafe';
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}
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