Xen with grsec?

Xen with grsec?

[Pasi Kärkkäinen]

Has anyone tried running grsec with xen (2.4) ?

Are there any expected problems, or should it be ok "out-of-the-box"? 
I have not yet tried patching xen-patched kernel with grsec.. Just wanted to
ask if somebody has already tried this.

-- Pasi Kärkkäinen
       
                                   ^
                                .     .
                                 Linux
                              /    -    \
                             Choice.of.the
                           .Next.Generation.


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Re: Xen with grsec?

[Jacob Gorm Hansen]

Pasi Kärkkäinen wrote:
> Has anyone tried running grsec with xen (2.4) ?
> 
> Are there any expected problems, or should it be ok "out-of-the-box"? 
> I have not yet tried patching xen-patched kernel with grsec.. Just wanted to
> ask if somebody has already tried this.

I am fairly sure you will run into infinite page-fault loops if you are 
trying to use the PaX 'software NX' implementation, because the call to 
Xen to update the page tables will frequently exhaust the associativity 
of the data-TLB.

You could find a way of implementing this part inside Xen though, by 
using an AVL or reserved bit to signify 'no execute', but this may be 
too much hassle.

The rest of grsec looks (from the description on the website) like it 
can be applied without problems.

Jacob


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Re: Xen with grsec?

[Milan Holzäpfel]

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On Tue, 23 Nov 2004 11:42:46 +0100
Jacob Gorm Hansen <jacobg@diku.dk> wrote:

> Pasi Kärkkäinen wrote:
> > Has anyone tried running grsec with xen (2.4) ?
> > 
> > Are there any expected problems, or should it be ok "out-of-the-box"? 
> > I have not yet tried patching xen-patched kernel with grsec.. Just wanted to
> > ask if somebody has already tried this.
> 
> I am fairly sure you will run into infinite page-fault loops if you are 
> trying to use the PaX 'software NX' implementation, [...]

What about hardware implementations? IIRC, the Athlon64 processors
(amongst others) implement such feature in hardware?  While I know that
there's usable version of Xen for AMD64 so far, can this feature also be
used in 32-Bit-mode?  (On the other hand, I'm not aware whether PaX will
use this feature or not...) 
...just jumping in because I'm interested in this too...

Regards,
Milan

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Re: Re: Xen with grsec?

[Jacob Gorm Hansen]

Milan Holzäpfel wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1

> What about hardware implementations? IIRC, the Athlon64 processors
> (amongst others) implement such feature in hardware?  While I know that
> there's usable version of Xen for AMD64 so far, can this feature also be
> used in 32-Bit-mode?  (On the other hand, I'm not aware whether PaX will
> use this feature or not...) 
> ...just jumping in because I'm interested in this too...

I suppose that would just work, though I think it requires PAE mode (64 
bit page table entries), does Xen support PAE now, I guess it does?

There was another similar patch from Redhat using segments instead of 
playing with the TLB, that will probably work with few or no modifications.

Jacob


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