Angular has some features that can break certain CSP (Content Security Policy) rules.
If you intend to implement these rules then you must tell Angular not to use these features.
This is necessary when developing things like Google Chrome Extensions or Universal Windows Apps.
The following rules affect Angular:
unsafe-eval
: this rule forbids apps to use eval
or Function(string)
generated functions
(among other things). Angular makes use of this in the $parse
service to provide a 30%
increase in the speed of evaluating Angular expressions.
unsafe-inline
: this rule forbids apps from inject custom styles into the document. Angular
makes use of this to include some CSS rules (e.g. ngCloak
and ngHide
).
To make these directives work when a CSP rule is blocking inline styles, you must link to the
angular-csp.css
in your HTML manually.
If you do not provide ngCsp
then Angular tries to autodetect if CSP is blocking unsafe-eval
and automatically deactivates this feature in the $parse
service. This autodetection,
however, triggers a CSP error to be logged in the console:
Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of
script in the following Content Security Policy directive: "default-src 'self'". Note that
'script-src' was not explicitly set, so 'default-src' is used as a fallback.
This error is harmless but annoying. To prevent the error from showing up, put the ngCsp
directive on an element of the HTML document that appears before the <script>
tag that loads
the angular.js
file.
Note: This directive is only available in the ng-csp
and data-ng-csp
attribute form.
You can specify which of the CSP related Angular features should be deactivated by providing
a value for the ng-csp
attribute. The options are as follows:
no-inline-style: this stops Angular from injecting CSS styles into the DOM
no-unsafe-eval: this stops Angular from optimizing $parse with unsafe eval of strings
You can use these values in the following combinations:
No declaration means that Angular will assume that you can do inline styles, but it will do
a runtime check for unsafe-eval. E.g. <body>
. This is backwardly compatible with previous versions
of Angular.
A simple ng-csp
(or data-ng-csp
) attribute will tell Angular to deactivate both inline
styles and unsafe eval. E.g. <body ng-csp>
. This is backwardly compatible with previous versions
of Angular.
Specifying only no-unsafe-eval
tells Angular that we must not use eval, but that we can inject
inline styles. E.g. <body ng-csp="no-unsafe-eval">
.
Specifying only no-inline-style
tells Angular that we must not inject styles, but that we can
run eval - no automatic check for unsafe eval will occur. E.g. <body ng-csp="no-inline-style">
Specifying both no-unsafe-eval
and no-inline-style
tells Angular that we must not inject
styles nor use eval, which is the same as an empty: ng-csp.
E.g.<body ng-csp="no-inline-style;no-unsafe-eval">
<html>
...
</html>
This example shows how to apply the ngCsp
directive to the html
tag.
<!doctype html>
<html ng-app ng-csp>
...
...
</html>
// Note: the suffix .csp
in the example name triggers
// csp mode in our http server!
<div ng-controller="MainController as ctrl">
<div>
<button ng-click="ctrl.inc()" id="inc">Increment</button>
<span id="counter">
{{ctrl.counter}}
</span>
</div>
<div>
<button ng-click="ctrl.evil()" id="evil">Evil</button>
<span id="evilError">
{{ctrl.evilError}}
</span>
</div>
</div>
angular.module('cspExample', [])
.controller('MainController', function() {
this.counter = 0;
this.inc = function() {
this.counter++;
};
this.evil = function() {
// jshint evil:true
try {
eval('1+2');
} catch (e) {
this.evilError = e.message;
}
};
});
var util, webdriver;
var incBtn = element(by.id('inc'));
var counter = element(by.id('counter'));
var evilBtn = element(by.id('evil'));
var evilError = element(by.id('evilError'));
function getAndClearSevereErrors() {
return browser.manage().logs().get('browser').then(function(browserLog) {
return browserLog.filter(function(logEntry) {
return logEntry.level.value > webdriver.logging.Level.WARNING.value;
});
});
}
function clearErrors() {
getAndClearSevereErrors();
}
function expectNoErrors() {
getAndClearSevereErrors().then(function(filteredLog) {
expect(filteredLog.length).toEqual(0);
if (filteredLog.length) {
console.log('browser console errors: ' + util.inspect(filteredLog));
}
});
}
function expectError(regex) {
getAndClearSevereErrors().then(function(filteredLog) {
var found = false;
filteredLog.forEach(function(log) {
if (log.message.match(regex)) {
found = true;
}
});
if (!found) {
throw new Error('expected an error that matches ' + regex);
}
});
}
beforeEach(function() {
util = require('util');
webdriver = require('protractor/node_modules/selenium-webdriver');
});
// For now, we only test on Chrome,
// as Safari does not load the page with Protractor's injected scripts,
// and Firefox webdriver always disables content security policy (#6358)
if (browser.params.browser !== 'chrome') {
return;
}
it('should not report errors when the page is loaded', function() {
// clear errors so we are not dependent on previous tests
clearErrors();
// Need to reload the page as the page is already loaded when
// we come here
browser.driver.getCurrentUrl().then(function(url) {
browser.get(url);
});
expectNoErrors();
});
it('should evaluate expressions', function() {
expect(counter.getText()).toEqual('0');
incBtn.click();
expect(counter.getText()).toEqual('1');
expectNoErrors();
});
it('should throw and report an error when using "eval"', function() {
evilBtn.click();
expect(evilError.getText()).toMatch(/Content Security Policy/);
expectError(/Content Security Policy/);
});