Re: [PATCH 2/3] binfmt_elf: Verify signature of signed elf binary

[Mimi Zohar]

On Wed, 2013-01-16 at 11:34 -0500, Vivek Goyal wrote:

> I read the comment in ima_bprm_check() being called from security_bprm_check(). 
> It says that files already open for write can't executed and files already
> open for exec can't be open for writes. That's fine. 
> 
> I was worried about anonymous pages being modified on swap and then
> faulted back in. It is not necessarily signature verification but making
> sure signed processes memory is not modified later by any unsigned process
> in anyway. And that includes disabling ptrace too.
> 
> So IMA stuff does not do anything to protect against process memory being
> modified using ptrace or by playing tricks with swap.

> I am not sure what will happen if I can bypass the file system and directly
> write on a disk block and modify executable. (Assuming one can get block
> information somehow). Does anything protect such modification? Will IMA
> detect it?

Sorry, this is out of scope for IMA.  Dmitry has looked into this, but
I'm not sure where it stands at the moment.

thanks,

Mimi

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