No, that's not the same.
There is no capability security on the OS level.
Otherwise Android wouldn't have a malware issue and iPhones wouldn't need to be locked up against third party apps.
There is no capability security on the OS level.
Otherwise Android wouldn't have a malware issue and iPhones wouldn't need to be locked up against third party apps.
>Otherwise Android wouldn't have a malware issue and iPhones wouldn't need to be locked up against third party apps.
Android malware is not as bad as what is possible with Windows malware. Over the years Google has been cracking down and working to remove permissions that apps can use without the user knowing. Unless the app has an exploit for the operating system it can't do much harm to you. iPhones have allowed for third party apps since the very first iphone a decade and a half ago.
Generally speaking, capabilities are not asked for; that would be a permission.
Capabilities can be used to implement permissions, but that's not what is usually meant by 'capability-based security'. Capabilities are essentially just inputs; a GPS-reading capability would be anything we can read GPS data from (e.g. a callback; or a pseudo-file handle; etc.).
Security is enforced by choosing who is given a capability (like a URL); we can get extra security by minting new capabilities, and revoking those which should no longer have access.
Permissions are not required to "do" things; they are enforced elsewhere, to determine whether that thing should succeed or fail. For example, giving out URLs to search engines, then trying to have the server reject requests that we don't want (AKA 'closing the barn door after the horse has bolted')
The operating system uses both capabilities and permissions.
Regardless, this is all implementation details and for the user it is equivalent. There is the same principle of least privilege where apps are limited in what they can do.
No, that's still wrong.
The Android framework uses something that goes a little bit in the direction of capabilities.
But the Android framework / runtime runs (by now) on an OS (Linux) that is not capability safe.
> Regardless, this is all implementation details and for the user it is equivalent.
No, of course not.
On a capability secure OS your mouse driver can't read the disk or do network request. Even if you would find an exploit in the driver.
That's a completely different level of security!
It's a fact that there is still no capability secure OS out there in broad use. (Fuchsia could be the first that brings this concept into mainstream. But this will take time. Also Fuchsia isn't as strict as it could be, for different reasons).
No, that are two fundamentally different concepts.
A capability is something that needs to be hold and passed to every call. If you can't show the needed capability (because you don't own it, in the sense that you're holding a special kind of object in your hands) you can't preform an action. On the very basic level: You just can't call a function because it needs a parameter of capability type.
This is fundamental different to permissions. Permissions are checked by the called code. You don't need to "pass a permission" alongside the actual action you try to perform.
Please read up at least the Wikipedia page as you seem to have some severe misconception about this topic: https://en.wikipedia.org/wiki/Capability-based_security
Capability based security means that applications are very limited in what they can do by default and need to be given capabilities in order to do something. Yes, one way to give an application a capability is by representing that capability by a token, but another way to give an application a capability is by giving it a permission.
If you want the term to refer to a specific implementation ignoring that it is identical from the end user's perspective then I'm fine in conceding.
> A capability (known in some systems as a key) is a communicable, unforgeable token of authority.
That's verbatim the second sentence on Wikipedia!
That's not "an implementation detail", it's core of the whole concept.
> Capability-based security is to be contrasted with an approach that uses traditional UNIX permissions and Access Control Lists.
> Although most operating systems implement a facility which resembles capabilities, they typically do not provide enough support to allow for the exchange of capabilities among possibly mutually untrusting entities to be the primary means of granting and distributing access rights throughout the system. A capability-based system, in contrast, is designed with that goal in mind.
That's not capability-based security: you have to do that whichever model is in use. The ocaps come in when you use dependency injection (aka "function call") everywhere to pass in rights to make use of resources. Neither Android nor iOS are meaningfully object-capability based.
No, that would be mandatory access control. Completely different concept.
Please remember from the first commented:
>Alas, we're in the timeline without capability based security. where users can't just give a file to a program at runtime using a (powerbox) dialog.
This is literally how Android already works today. An app can not read a random file from the system. It has to open a file selector and you have to select a file before an app is able to read it.
That's not implemented on the OS level.
Yes, it is. The Storage Access Framework is a part of the operating system.
That's completely wrong.
The whole point of capabilities is that they're unforgeable.
You can't mint a capability! You need to get it passed "form above". Nobody can create capabilities from thin air (not even the OS kernel).
But I'm coming to the conclusion that you're only trolling. You refuse to look at the facts and definitions, and just repeat the same nonsense over and over. I'm done here as I obviously can't help you understand this topic.
seL4 is just the core of a micro kernel. The hard part would be to build an OS around that.
You know, the same way that you ask for code review before merging to prod.
I've liked Wikipedia on that topic already in this thread. Please take a look.
And for bystanders, here's the Wikipedia link: https://en.wikipedia.org/wiki/Capability-based_security
My reasoning was that it would be rude to link to myself, to a comment that showed up at this time just on the same screen as this one.
But I guess you're right. A link would not hurt, but make it more easy to discover the mentioned content.