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 Post subject: Userspace with DPL 0.
PostPosted: Mon Oct 05, 2015 3:46 am 
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Hi,

Could userspace still being considered userspace if it doesn't mess with the kernel virtual space but use DPL 0 permission (it can alter interrupt states and so on)?

Granted, that can be dangerous and let all sorts of bad things happen.

But, is it still considered userspace?

Bye


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 Post subject: Re: Userspace with DPL 0.
PostPosted: Mon Oct 05, 2015 4:02 am 
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Hi,

AlexHully wrote:
Could userspace still being considered userspace if it doesn't mess with the kernel virtual space but use DPL 0 permission (it can alter interrupt states and so on)?


Yes; it could still be considered user space (but couldn't be considered secure, unless the OS is doing something else to ensure isolation - e.g. managed code).

Don't forget that you could set IOPL=3 to allow CPL=3 tasks to use some things (HLT, CLI/STI, IO ports) without given them full access to things like CR0, CR3, MSRs, etc.


Cheers,

Brendan

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 Post subject: Re: Userspace with DPL 0.
PostPosted: Mon Oct 05, 2015 6:59 am 
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Perfect.

Thanks a lot Brendan :)


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