linux-kernel - Re: [PATCH] Access control in Xen privcmd_ioctl

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Date:	Fri, 11 Jan 2013 12:39:54 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Tamas Lengyel <tamas.lengyel@...tific.com>
Cc:	jeremy@...p.org, Daniel De Graaf <dgdegra@...ho.nsa.gov>,
	xen-devel@...ts.xensource.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Access control in Xen privcmd_ioctl_mmap

On Mon, Dec 31, 2012 at 03:44:30PM -0500, Tamas Lengyel wrote:
> In the privcmd Linux driver two checks in the functions
> privcmd_ioctl_mmap and privcmd_ioctl_mmap_batch are not needed as they
> are trying to enforce hypervisor-level access control.  They should be
> removed as they break secondary control domains when performing dom0
> disaggregation. Xen itself provides adequate security controls around
> these hypercalls and these checks prevent those controls from
> functioning as intended.
> 
> The patch applies to the stable Linux 3.7.1 kernel.

Hm, I get this:

atching file drivers/xen/privcmd.c
Hunk #1 FAILED at 196.
patch: **** malformed patch at line 91: *udata, int version)

Anyhow I fixed it up.

Should this patch also be back-ported to the stable trees?

> 
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@...tific.com>
> Cc: Daniel De Graaf <dgdegra@...ho.nsa.gov>
> Cc: xen-devel@...ts.xensource.com
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/xen/privcmd.c |    6 ------
>  1 files changed, 0 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 71f5c45..adaa260 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -196,9 +196,6 @@ static long privcmd_ioctl_mmap(void __user *udata)
>         LIST_HEAD(pagelist);
>         struct mmap_mfn_state state;
> 
> -       if (!xen_initial_domain())
> -               return -EPERM;
> -
>         if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
>                 return -EFAULT;
> 
> @@ -316,9 +313,6 @@ static long privcmd_ioctl_mmap_batch(void __user
> *udata, int version)
>         int *err_array = NULL;
>         struct mmap_batch_state state;
> 
> -       if (!xen_initial_domain())
> -               return -EPERM;
> -
>         switch (version) {
>         case 1:
>                 if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
--
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