What does the following mean? I assume chrome refers to Google's webbrowser Chrome, but does it have its own special protocol (like http:// and ftp://)?
<iframe src="chrome://extension/content/web/web.htm" />"
It has several meanings - Documentation
This is probably what you're looking for:
A chrome:// URL
An URL using the chrome:// protocol. Code loaded from a chrome URL has extended, or chrome,privileges. XUL-based applications load the code for their interface from chrome:// URLs.
Chrome privileges
The code running with chrome privileges is allowed to do everything, unlike the web content, which is restricted in several ways.
It doesn't; chrome:// is a cue to what's known as a protocol handler. Basically, protocol handlers register a protocol scheme, and the browser will then pass off URLs matching that scheme to the handler.
One example of this functionality that you're probably familiar with is mailto:, which is not a protocol, but merely informs the browser to hand off the subsequent URI to a mail program.
It's a special scheme used to refer to something inside the browser itself, or an add-on. There's probably no protocol per se, it just causes Chrome to access an internal resource in some way.
Also, "chrome" probably refers to "the stuff around the page" (i.e. the browser UI) rather than Google Chrome, although it is also what Google Chrome is named after. Firefox uses the same scheme for its internal things.
Related
When you're writing the manifest.json file, you have to specify matches for your content scripts. The http and https work fine, but if I try to include chrome://*/* or any variant of it, I get an error that I'm attempting to use an invalid scheme for my matches.
Is it not allowed?
By default you cannot run on a chrome:// url page.
However, there is an option in chrome://flags/#extensions-on-chrome-urls:
Extensions on chrome:// URLs (Mac, Windows, Linux, Chrome OS, Android)
Enables running extensions on chrome:// URLs, where extensions explicitly request this permission.
You still have to specify pages that your extension can run on and wildcards are not accepted - so you have to specify the full URL eg chrome://extensions/
The authorized schemes for matches are http, https, file, ftp.
Therefore, chrome is not a valid scheme.
Yes, it is not allowed. You can't link to them from hrefs on a webpage either.
I recently published a Chrome extension (Source Code) and now discover some broken incoming links on the extension's website which must be related to that extension:
/track_install/search/ext/free/mebkekakcnabgndiakbbefcgpedlaidp/mixcloud_downloader
/webstore/detail/ext/free/mebkekakcnabgndiakbbefcgpedlaidp/mixcloud_downloader
On the chrome extension webstore I don't find such links. Do you have any idea where those links come from and what's their purpose? Would users exepect anything else than a 404 on that URLs?
The website is referenced in the extension's manifest homepage_url field and on the webstore item in the "Websites" field.
Update: I just noticed again one such request where the referer comes from this question.
Normally, those URLs are relative to the Webstore and are used for Analytics tracking and this stat page (only available to you). See this mention, for example.
/track_install/... is, quite obviously, used as a beacon to track installs.
/webstore/detail/ext/free/... tracks opening your extension's listing in Web Store.
Here's documentation on homepage_url, which I believe influenced this, including this quote:
If you distribute your extension using the Chrome Web Store, the homepage URL defaults to the extension's own page.
I believe that it's either a bug that those are sent out to your server instead, or a feature I haven't seen documented anywhere to let you track those instead. Note that those are just beacons sent from analytics code; you don't need to serve content on them.
In any case, it's worth reporting, either on the bugtracker or via the exceptionally well-hidden developer support form.
I have a site which is completely on https: and works well, but, some of the images served are from other sources e.g. ebay, or Amazon.
This causes the browser to prompt a message: "this website does not supply identity information"
How can I avoid this? The images must be served from elsewhere sometimes.
"This website does not supply identity information." is not only about the encryption of the link to the website itself but also the identification of the operators/owners of the website - just like it actually says. For that warning (it's not really an error) to stop, I believe you have to apply for the Extended Validation Certificate https://en.wikipedia.org/wiki/Extended_Validation_Certificate. EVC rigorously validates the entity behind the website not just the website itself.
Firefox shows the message
"This website does not supply identity information."
while hovering or clicking the favicon (Site Identity Button) when
you requested a page over HTTP
you requested a page over HTTPS, but the page contains mixed passive content
HTTP
HTTP connections generally don't supply any reliable identity information to the browser. That's normal. HTTP was designed to simply transmit data, not to secure the data it transmits.
On server side you could only avoid that message, if the server would start using a SSL certificate and the code of the page would be changed to exclusively use HTTPS requests.
To avoid the message on client side you could enter about:config in the address bar, confirm you'll be careful and set browser.chrome.toolbar_tips = false.
HTTPS, mixed passive content
When you request a page over HTTPS from a site which is using a SSL certificate, the site does supply identity information to the browser and normally the message wouldn't appear.
But if the requested page embeds at least one <img>, <video>, <audio> or <object> element which includes content over HTTP (which won't supply identity information), than you'll get a so-called mixed passive content * situation.
Firefox won't block mixed passive content by default, but only show said message to warn the user.
To avoid this on server side, you'd first need to identify which requests are producing mixed content.
With Firefox on Windows you can use Ctrl+Shift+K (Control-Option-K on Mac) to open the web console, deactivate the css, js and security filters, and press F5 to reload the page, to show all the requests of the page.
Then fix your code for each line which is showing "mixed content", i.e. change the appropriate parts of your code to use https:// or, depending on your case, protocol-relative URLs.
If the external site an element is requested from doesn't use a SSL certificate, the only chance to avoid the message would be to copy the external content over to your site so your code can refer to it locally via HTTPS.
* Firefox also knows mixed active content, which is blocked by default, but that's another story.
Jürgen Thelen's answer is absolutely correct. If the images (quite often the case) displayed on the page are served over "http" the result will be exactly as described no matter what kind of cert you have, EV or not. This is very common on e-commerce sites due to the way they're constructed. I've encountered this before on my own site AND CORRECTED IT by simply making sure that no images have an "http" address - and this was on a site that did not have an EV cert. Use the ctrl +shift +K process that Jürgen describes and it will point you to the offending objects. If the path to an object is hard coded and the image resides on your server (not called from somewhere else) simply remove the "http://servername.com" and change it to a relative path instead. Correct that and the problem will go away. Note that the problem may be in one of the configuration files as well, such as one of the config.php files.
The real issue is that Firefox's error message is misleading and has nothing to do with whether the SSL is an EV cert or not. It really means there is mixed content on the page but doesn't say that. A couple of weeks ago I had a site with the same problem and Firefox displayed the no-identity message. Chrome, however, (which I normally don't use) displayed an exclamation mark instead of a lock. I clicked on it and it said the cert was valid (with a green dot), it was a secure connection (another green dot), AND had "Mixed Content. The site includes HTTP resources" which was entirely accurate and the source of the problem (with a red dot). Once the offending paths were changed to relative paths, the error messages in both Firefox and Chrome disappeared.
For me, it was a problem of mixed content. I forced everything to make HTTPS requests on the page and it fixed the problem.
For people who come here from Google search, you can use Cloudflare's (free) page rules to accomplish this without touching your source code. Use the "Always use HTTPS" setting for your domain.
You can also transfrom http links to https links using url shortener www.tr.im. That is the only URL-shortener I found that provides shorter links through https.
You just have to change it manually from http://tr.im/xxxxxx to https://tr.im/xxxxxx.
As a web developer, is there any way to prevent a user's Chrome extensions from being applied to my site? i.e. a header, meta tag, anything? Additionally, if there is, is there also a way to whitelist particular extensions?
It's not possible. At the web server end, you are only only able to control what the browser will allow you to control. In simple terms, this means you can control the data (HTML, javascript, headers etc) that you send back to it. That's about it.
Can't you create a Content Security Policy (CSP) and block inline javascript and only allow javascript from specific domains? You could even create a CSP in report-only mode and collect violation reports via something like https://report-uri.io/
In Firefox or Chrome I'd like to prevent a private web page from making outgoing connections, i.e. if the URL starts with http://myprivatewebpage/ or https://myprivatewebpage/ in a browser tab, then that browser tab must be restricted so that it is allowed to load images, CSS, fonts, JavaScript, XmlHttpRequest, Java applets, flash animations and all other resources only from http://myprivatewebpage/ or https://myprivatewebpage/, i.e. an <img src="http://www.google.com/images/logos/ps_logo.png"> (or the corresponding <script>new Image(...) must not be able to load that image, because it's not on myprivatewebpage. I need a 100% and foolproof solution: not even a single resource outside myprivatewebpage can be accessible, not even at low probability. There must be no resource loading restrictions on Web pages other than myprivatewebpage, e.g. http://otherwebpage/ must be able to load images from google.com.
Please note that I assume that the users of myprivatewebpage are willing to cooperate to keep the web page private unless it's too much work for them. For example, they would be happy to install a Chrome or Firefox extension once, and they wouldn't be offended if they see an error message stating that access is denied to myprivatewebpage until they install the extension in a supported browser.
The reason why I need this restriction is to keep myprivatewebpage really private, without exposing any information about its use to webmasters of other web pages. If http://www.google.com/images/logos/ps_logo.png was allowed, then the use of myprivatewebpage would be logged in the access.log of Google's ps_logo.png, so Google's webmasters would have some information how myprivatewebpage is used, and I don't want that. (In this question I'm not interested in whether the restriction is reasonable, but I'm only interested in the technical solutions and its strengths and weaknesses.)
My ideas how to implement the restriction:
Don't impose any restrictions, just rely on the same origin policy. (This doesn't provide the necessary protection, the same origin policy lets all images pass through.)
Change the web application on the server so it generates HTML, JavaScript, Java applets, flash animations etc. which never attempt to load anything outside myprivatewebpage. (This is almost impossibly hard to foolproof everywhere on a complicated web application, especially with user-generated content.)
Over-sanitize the web page using a HTML output filter on the server, i.e. remove all <script>, <embed> and <object> tags, restrict the target of <img src=, <link rel=, <form action= etc. and also restrict the links in the CSS files. (This can prevent all unwanted resources if I can remember all HTML tags properly, e.g. I mustn't forget about <video>. But this is too restrictive: it removes all dyntamic web page functionality like JavaScript, Java applets and flash animations; without these most web applications are useless.)
Sanitize the web page, i.e. add an HTML output filter into the webserver which removes all offending URLs from the generated HTML. (This is not foolproof, because there can be a tricky JavaScript which generates a disallowed URL. It also doesn't protect against URLs loaded by Java applets and flash animations.)
Install a HTTP proxy which blocks requests based on the URL and the HTTP Referer, and force all browser traffic (including myprivatewebpage, otherwebpage, google.com) through that HTTP proxy. (This would slow down traffic to other than myprivatewebpage, and maybe it doesn't protect properly if XmlHttpRequest()s, Java applets or flash animations can forge the HTTP Referer.)
Find or write a Firefox or Chrome extension which intercepts all outgoing connections, and blocks them based on the URL of the tab and the target URL of the connection. I've found https://developer.mozilla.org/en/Setting_HTTP_request_headers and thinkahead.js in https://addons.mozilla.org/en-US/firefox/addon/thinkahead/ and http://thinkahead.mozdev.org/ . Am I correct that it's possible to write a Firefox extension using that? Is there such a Firefox extension already?
Some links I've found for the Chrome extension:
http://www.chromium.org/developers/design-documents/extensions/notifications-of-web-request-and-navigation
https://groups.google.com/a/chromium.org/group/chromium-extensions/browse_thread/thread/90645ce11e1b3d86?pli=1
http://code.google.com/chrome/extensions/trunk/experimental.webRequest.html
As far as I can see, only the Firefox or Chrome extension is feasible from the list above. Do you have any other suggestions? Do you have some pointers how to write or where to find such an extension?
I've found https://developer.mozilla.org/en/Setting_HTTP_request_headers and thinkahead.js in https://addons.mozilla.org/en-US/firefox/addon/thinkahead/ and http://thinkahead.mozdev.org/ . Am I correct that it's possible to write a Firefox extension using that? Is there such a Firefox extension already?
I am the author of the latter extension, though I have yet to update it to support newer versions of Firefox. My initial guess is that, yes, it will do what you want:
User visits your web page without plugin. Web page contains ThinkAhead block that would send a simple version header to the server, but this is ignored as plugin is not installed.
Since the server does not see that header, it redirects the client to a page to install the plugin.
User installs plugin.
User visits web page with plugin. Page sends version header to server, so server allows access.
The ThinkAhead block matches all pages that are not myprivatewebpage, and does something like set the HTTP status to 403 Forbidden. Thus:
When the user visits any webpage that is in myprivatewebpage, there is normal behaviour.
When the user visits any webpage outside of myprivatewebpage, access is denied.
If you want to catch bad requests earlier, instead of modifying incoming headers, you could modify outgoing headers, perhaps screwing up "If-Match" or "Accept" so that the request is never honoured.
This solution is extremely lightweight, but might not be strong enough for your concerns. This depends on what you want to protect: given the above, the client would not be able to see blocked content, but external "blocked" hosts might still notice that a request has been sent, and might be able to gather information from the request URL.