Chromium Blog

Native Client Brings Sandboxed Native Code to Chrome Web Store Apps

Thursday, August 18, 2011

Native Clientbeta channelFile APIWebSocketsNative Client sandboxChrome sandboxFAQNative Client sitePortable Native ClientLLVMPosted by Christian Stefansen, Product Manager

Connecting Web Apps with Web Intents

Thursday, August 4, 2011

var intent = new Intent(Intent.EDIT, ‘image/png’, getImageDataURI());
window.navigator.startActivity(intent, loadEditedImage);

// This callback will be called when the service replies with the edited
// image data.
function loadEditedImage(data) {
var image = document.getElementById(‘image’);
setImageData(image, data);
}
<intent
action=”http://webintents.org/edit”
type=”image/*”
/>var intent = window.intent;
memeImg.src = intent.data;

memegenForm.onsubmit = function() {
// Transform the image - meme it.
addMemeTaglines(memeImg, memeTopText, memeBottomText);

// Send the generated meme back to the client.
intent.postResult(getImageData(memeImg));
};postResult()startActivity()exploringexamplesJavaScript shimPosted by James Hawkins, Software Engineer

New WebSocket Protocol: Secure and Extensible

Monday, August 1, 2011

The WebSocket protocol specification is now largely stable, having solved previous security concerns. As such, we’ve updated Chromium to support the latest version (draft-ietf-hybi-thewebsocketprotocol-10) on the dev channel (14.0.835.2). Given that the specification is now in “last-call” and and no further breaking changes are expected, it should now be safe to use WebSockets for production application development.
Please note that the new protocol is incompatible with one which Chromium previously supported (draft-ietf-hybi-thewebsocketprotocol-00), so existing WebSocket-based services may break. Please upgrade your servers to ones which support HyBi 10. Existing JavaScript code still works once the protocol version used by the browser and server match.
The new protocol introduces some exciting new features like binary message support and compression support, but these are not quite ready yet in Chrome and will come shortly - hang tight!
See the specs and discussion at W3C and WHATWG (spec, whatwg list) and IETF (spec, HyBi list) for more detail about the new protocol.
We’re more than happy to hear your feedback, and encourage you to file any bugs you find on our issue tracker.Posted by Takeshi Yoshino, Software Engineer

Chrome Web Store: Now with more international support and with In-App Payments

Monday, August 1, 2011

more users around the worldadditional monetization opportunitiesrecently launchedIn App Payments APIdocssample app complete with source codeour short videolocalize your app listingdeveloper discussion groupPosted by Elvin Lee, Software Engineer

Writing Extensions More Securely

Friday, July 22, 2011

built-in protectionsmanyarticlesMinimize your permissions (*/*) permissions for hosts if you only need to access a couple, and don’t copy and paste your manifest from example code blindly. Review your manifest to make sure you’re only declaring what you need. This applies to permissions like tabs, history, cookies, etc. in addition to host permissions. For example, if all you’re using is chrome.tabs.create, you don’t actually need the tabs permission.

Use content_security_policy in your manifest

Starting in Chrome 14, we will begin supporting Content Security Policy in extensions via the content_security_policy manifest field. This allows you to control where scripts can be executed, and it can be used to help reduce your exposure to cross-site scripting vulnerabilities. For example, to specify that your extension loads resources only from its own package, use the following policy:

"content_security_policy": "default-src 'self'"

If you need to include scripts from specific hosts, you can add those hosts to this property.

Don’t use <script src> with an HTTP URL

When you include javascript into your pages using an HTTP URL, you’re opening your extension up to man-in-the-middle (MITM) attacks. When you do so in a content script, you have a similar effect on the pages you’re injected into. An attacker on the same network as one of your users could replace the contents of the script with content that they control. If that happens, they could do anything that your page can do.

If you need to fetch a remote script, always use HTTPS from a trusted source.

Don’t use eval()

The eval() function is very powerful and you should refrain from using it unless absolutely necessary. Where did the code come from that you passed into eval()? If it came from an HTTP URL, you’re vulnerable to the same issue as the previously mentioned <script> tag. If any of the content that you passed into eval() is based on content from a random web page the user visits, you’re vulnerable to escaping bugs. For example, let’s say that you have some code that looks like this:

function displayAddress(address) { // address was detected and grabbed from the current page
eval("alert('" + address + "')");
}

If it turned out that you had a bug in your parsing code, the address might wind up looking something like this:

'); dosomethingevil();

There’s almost always a better alternative to using eval(). For example, you can use JSON.parse if you want to parse JSON (with the added benefit that it runs faster). It’s worth the extra effort to use alternatives like this.

Don’t use innerHTML or document.write()

It’s really tempting to use innerHTML because it’s much simpler to generate markup dynamically than to create DOM nodes one at a time. However, this again sets you up for bugs in escaping your content. For example:

function displayAddress(address) { // address was detected and grabbed from the current page
myDiv.innerHTML = "<b>" + address + "</b>");
}

This would allow an attacker to make an address like the following and once again run some script in your page:

<script>dosomethingevil();</script>

Instead of innerHTML, you can manually create DOM nodes and use innerText to insert dynamic content.

Beware external content

In general, if you’re generating dynamic content based on data from outside of your extension (such as something you fetched from the network, something you parsed from a page, or a message you received from another extension, etc.), you should be extremely careful about how you use it. If you use this data to generate content within your extension, you might be opening your users up to increased risk.

You can also read a few more examples of the issues discussed here in our extension docs. We hope these recommendations help you create better and safer extensions for everyone.

Posted by Erik Kay, Software Engineer

Chrome Extensions: Now with more powerful scripts and improved proxy management.

Wednesday, July 13, 2011

sample extensionbackground pagechrome.extension.onRequestrewrite the extensionGM_xmlhttpRequestBook Burromatch patternsmatchesexclude_matches@run-ata scriptProxy Extension APIProxyRulesProxy AnywhereProxy SwitchyPlusPosted by Tessa MacDuff and Mihai Parparita, Software Engineers

Using Cross-domain images in WebGL and Chrome 13

Wednesday, July 6, 2011

security issueshaders could be usedupdatedCORSCORS support.crossOriginvar img = document.createElement('img');
img.onload = function(e) { … };
img.crossOrigin = ''; // no credentials flag. Same as img.crossOrigin='anonymous'
img.src = 'http://other-domain.com/image.jpg';ctx.drawImage()origin-clean flagctx.toDataURL()ctx.getImageData().crossOriginvar img = document.createElement('img');
img.onload = function(e) {
ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
var url = canvas.toDataURL(); // Read succeeds, canvas won't be dirty.
};
img.crossOrigin = '';
img.src = 'http://other-domain.com/image.jpg';use of CORSChrome dev channelPosted by Eric Bidelman, Developer Advocate