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That is not the argument that Gruber is making. That is his factual summary of the current situation.

The argument that is being made is that Apple currently considers it a security risk to enable the new Nitro Javascript engine for all applications, preferring instead to enable it only for Safari Mobile, and leave other applications using the older javascript engine.

Possibly forever, destroying web apps on the iPhone completely, or possibly just until Apple is able to sort out the security implications of having to mark in memory pages as executable.

You get to chose which scenario you think is most plausible.

Well, he's making multiple arguments, and that first one was an argument. My position is that it is a ridiculous one.

I am also not entering the discussion of native apps running UIWebView. I have zero comment on that (mainly because I'm disinterested in the subject).

My only comment is on home-screen web apps, which are 100% equivalent to opening the page on your browser. They deserve more privileges because the user had to make a decision to install them. It makes no sense to me whatsoever that a random advertisement loaded from some insecure URL on a web page is allowed to access Nitro and web cache, but a web app that I trust enough to install on my home screen is not.

Ironically, I'm actually pretty happy with this decision, because I believe all apps should be in the browser. I'm just telling it like it is when people make nonsensical arguments.

You are entering the discussion of native apps running UIWebView because (according to Gruber) that is exactly how home-screen web apps are implemented.

"My only comment is on home-screen web apps, which are 100% equivalent to opening the page on your browser."

From Gruber:

"Web apps that are saved to the home screen do not run within Mobile Safari. They’re effectively saved as discrete apps — thin wrappers around the UIWebView control."

"I'm just telling it like it is when people make nonsensical arguments."

Your failure to read and understand his arguments have made them sound nonsensical to you. This is not his fault.

I initially thought you were just splitting hairs, but seeing as you've used this argument somewhere else in this thread I think this might be a genuine thought you have so I will take the time to explain why home-screen web apps are absolutely nothing like other native apps on the system, and actually essentially the same as loading a web page in MobileSafari. So for starters, let us observe that there are three instances where JS can run on iOS that we care about:

1. MobileSafari, from a web page loaded from a URL.

2. Home-Screen Web Apps, web pages loaded from a URL that the user then 'saves to the homes screen' which are loaded in some mysterious, but APPLE WRITTEN, "wrapper" process X.

3. UIWebViews within native apps that you buy on the App Store.

Now, my position is that (1) and (2) are for all intents and purposes the same, and (3) is possibly different. So, the whole argument about turning it off for UIWebView is that the interaction between native code and Nitro might offer an additional vector of security concern. Well, in both (1) and (2), there is no user native code. It literally just either downloads the JS off the web, or reloads it straight from the web. All the native code is written PURELY by Apple. So in a world where the only user modifiable code comes from the web, then clearly this is the same as where we started with MobileSafari. The additional thing to realize, is that unlike native apps (3), home-screen web apps (2) are NOT code signed, just like web pages (1). So that also nullifies the argument that allowing Nitro on home-screen web apps would go against Apple's code signing policies.

Hopefully that explains my thinking a little bit clearer.

Once again, I am very willing to believe that they had a deadline to meet, and turning it on for home-screen web apps got punted. That makes perfect sense. The security argument however falls flat on its face.

You seem to be missing a key point.

The way Apple implemented Home-Screen Web Apps was by placing a thin wrapper around a UIWebView.

Hence, Home-Screen Web Apps are not like Mobile Safari at all in actual implementation.

They are, instead, exactly like an iOS application developed by a third party developer who put a thin wrapper around a UIWebView.

Hence, they do not get the same special privileges as Safari Mobile.

That is a fact of their implementation.

You seem to confusing facts with claims on a blog written by a third party. It's not hard to believe Web.app (the process which runs home screen apps) uses UIWebView or a close cousin, but neither you nor Gruber (or anyone on this site) has offered any evidence of that fact.

I find the fact that Web.app behaves exactly like every other application that uses a UIWebView to be very compelling evidence that Web.app is an application uses UIWebView.

The alternative appears to be that to create Web.app they went to all the trouble of reusing the Mobile Safari code, and then methodically went through and broke things such that it behaves exactly like every other application that uses UIWebView.

This would seem like an unreasonable way to get an application that behaves exactly like an application that uses UIWebView.

I think Tolmasky's point was that, even though Web.app embeds the same UIWebView as non-Apple native apps, Web.app was written by Apple. Apple could enable Nitro JIT for Web.app because its native code was written (and audited) by Apple. The only third-party code executed by Web.app is JavaScript that is already assumed to be safe enough to use the Nitro JIT in Mobile Safari.

yes, I think it was.

It makes a heap of assumptions though, and feels kind of like a non-techie person saying "why dont you just whip up a GUI app to trace my IP". Enabling Nitro JIT for UIWebView for some applications without enabling it for every app in the app store is probably more difficult than toggling a switch.

They deserve more privileges because the user had to make a decision to install them

I think it is technically different, but on other systems, the HTML pages I put on my desktop have fewer privileges than the ones I load from web sites. (https://bugzilla.mozilla.org/show_bug.cgi?id=230606)

As to the subject at hand: one line of reasoning says that not allowing JIT-ting for home-screen apps is an oversight; home-screen apps apparently do not run in the Safari process. I guess there is no way to find out whether that is true. If Apple fixes it in the next firmware update, one could argue either that they fixed the problem, or that they stalled fixing it for as long as they could get away with, and I am sure the internet will be filled with such arguments, even if that next update appears tomorrow.

Finally, for UIWebView, a secure solution could exist: provide a system call that does "javascript source code in, executable code block out". I do not know whether that could be made performant enough, though, given that the JIT-ter must be very fine-grained, must update existing code blocks, etc. It definitely would be quite a bit of work.

Edit: yay! you changed your post while I wrote mine.

Would you concede that there could be a security diff between JIT and not JIT?

All Gruber is arguing is:

1) that there is a significant difference in security

2) that Apple didn't release any JIT for webkit all this time [edit: since 2008] because of security concerns

3) that Apple did not go out of its way to remove JIT from those instances of webkit that occurr outside of Mobile Safari

4) that perhaps Apple is simply rolling it out gradually

I don't see how any of this is ridiculous or could be called "bending over backwards" unless you are pre-loaded with a bias against Gruber.

There goes what little karma I earned since 2008.

2) They didn't release it, one imagines, because it is hardware specific, and originally written for x86 not ARM.

Are you saying you are not able to concede my original statement: that JIT vs NOT JIT does [edit: meant to say "could" instead of "does"] constitute a significant security difference?

You should read my other comments on this thread. All of them basically start with "yes JIT may be less secure". That is not the argument I am making: http://news.ycombinator.com/item?id=2338724

Elsewhere in the comments I'm reading HN folks who agree that there are security implications with having writeable code pages available to native apps, and that it's reasonable for some of the JIT stuff to appear in Mobile Safari and not in native apps (although there are other approaches Apple may pursue in the future).

Have you read these arguments? Do you disagree with them? Or are you saying something else?

Just trying to understand...

For starters, my argument is only about MobileSafari (MS) and home-screen web apps.

If you read my other posts I think you'll see I have no issue with the idea that there may be a security issue with JIT. That is fine and acceptable.

What I have an issue with is the idea that MobileSafari is somehow the safest place to put it. If there is a security issue, then MobileSafari is clearly the absolute least safe place to put it (vs homescreen web apps), since any malicious web page has access to it. That includes random ads loaded on otherwise safe web pages. The user is not prompted when entering a web page if they want to use Nitro or not, so basically anything goes on the open web. If a security flaw is discovered in Nitro, I have only to place it on an ad that gets deployed to popular sites to take advantage of it. And Apple's only recourse is to issue an entire system upgrade and hope people update.

Home-screen web apps are thus at least as safe as MobileSafari, since they are literally just bookmarks that load web pages (in a different process and without chrome, but fundamentally the same, no access to any other native code or anything). They are in fact arguably more safe, because the user has to first grant it "home-screen" status. This is a sensible time to ask the user if this ONE app should deserve more privileges than the rest of the wild-west web. In other words, had apple done the opposite, ONLY allowing home-screen web apps access to Nitro, it would make a lot of security sense, especially because Apple could warn the user before they download the app saying "downloading this app gives it access to the special Nitro engine, which may be less secure...".

I am not arguing with you, I was only trying to distinguish between saying "Gruber could possibly be right, but I think he is wrong" and saying "Gruber can't possibly be right, and he ought to know better."

The situation is complicated by the fact that he is reporting what Apple is doing and what he has been told is the motivation for doing so. So he could be right that Apple is doing this, but you assert that Apple is wrong. Or that Apple is doing this, but not for the reasons they give.

You assert that there is no vulnerability in home screen apps wrapping UIWebView that isn't in Mobile Safari, and thus there is no downside to granting writeable code page permission to home screen apps. Ok, I think I understand what you are saying, why you are saying it, and what you would do in Apple's shoes.

His point is that HomeScreen web apps (for lack of a better term) are fundamentally exactly as secure as MobileSafari.

Even a technical argument is somewhat hard to fathom, since it should be a trivially simple thing to enable, but given that none of us can see the code it's at least possible.

As far as native apps with embedded UIWebViews, this is a believable technical argument, though it isn't obviously true either. In other words, the political argument isn't significantly less likely than the technical one.

From Gruber:

"Web apps that are saved to the home screen do not run within Mobile Safari. They’re effectively saved as discrete apps — thin wrappers around the UIWebView control."

What the GP is arguing is that web apps pinned to the home screen are no different from those same web apps viewed in a browser and therefore, there doesn't seem like there should be any security issue involved in it.

Someone (who I think works on Cydia - the Jailbreak App Store) commented about this further down:

Of course, this means that there is no real good reason why Apple has disabled Nitro for full-screen web applications (that I at least yet understand), and so I'd expect that this was frankly just a silly oversight

The "home screen bookmark" app is based on MobileSafari, but clearly isn't the same code base. I understand that your company would benefit from improved offline app performance, but it's likely that developer time and patience will fix the problem.

If you read my later reply, you'll see that I actually prefer the way things are, I just don't like misinformation. I am perfectly capable of accepting that its a matter of engineering time to get this to work. What I am not OK with is the notion that Safari is somehow a "trusted" app where this is not a security concern, whereas a home-screen web app is a security concern. There is no such thing as a trusted browser, any random malicious ad loaded in an iframe can have access to Nitro. Home screen web apps are necessarily just as safe or more safe than web pages.

From Gruber:

"Web apps that are saved to the home screen do not run within Mobile Safari. They’re effectively saved as discrete apps — thin wrappers around the UIWebView control."

Apple clearly believes that there are important security risks associated with their Nitro Javascript Engine.

I have no trouble at all believing that they have been able to mitigate those concerns for Safari Mobile by using a solution that is not appropriate when applied to any arbitary App that may choose to include a UIWebView.

"Web apps that are saved to the home screen", despite being "thin wrappers around the UIWebView control", are not "any arbitary App that may choose to include a UIWebView".

If they can make it work for Mobile Safari, they can make it work for a "thin wrapper" without working for all UIWebViews.

really? It seems to me that there are clear technical differences.

Im interested in your thoughts though, how would you allow one arbitarily large set of applications with arbitary names to use the Nitro Javascript engine via UIWebView, and still ensure that no third party developer could enable the ability on their own applications?

The way I would do it for a single application is enable a special case for it in the underlying OS....

Make the template app static, sign it with whatever special permissions MobileSafari has. (I'm assuming that some special permission is needed, signed by apple.)

Instantiate the app by copying it and placing the files related to the specific instance (manifest, html, cached files) in the standard mutable data directories (Documents, Cache, ...), which wouldn't affect the signature. (The name of the app and icon would have to excluded from the signature.)

If this is how things work now, I wouldn't be surprised if the lack of Nitro was just an oversight on Apple's part (i.e. they forgot to give the template app the right permissions). If home page web apps are granted a special exception to the usual app-signing, I could imagine that they can't give them these permissions without leaking them to everyone.