On Fri, 2012-06-29 at 14:08 -0400, rmarwah@xxxxxxxxxxxxxxxxxx wrote:
> From: Richa Marwaha <rmarwah@xxxxxxxxxxxxxxxxxx>
>
> This patch provides AppArmor policy updates for the QEMU bridge helper.
> The QEMU bridge helper is a SUID executable exec'd by QEMU that drops
> capabilities to CAP_NET_ADMIN and adds a tap device to a network bridge.
>
> Signed-off-by: Richa Marwaha <rmarwah@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Corey Bryant<coreyb@xxxxxxxxxxxxxxxxxx>
> ---
> examples/apparmor/libvirt-qemu | 21 ++++++++++++++++++++-
> 1 files changed, 20 insertions(+), 1 deletions(-)
>
> diff --git a/examples/apparmor/libvirt-qemu b/examples/apparmor/libvirt-qemu
> index 10cdd36..766a334 100644
> --- a/examples/apparmor/libvirt-qemu
> +++ b/examples/apparmor/libvirt-qemu
> @@ -1,4 +1,4 @@
> -# Last Modified: Mon Apr 5 15:11:27 2010
> +# Last Modified: Fri Mar 9 14:43:22 2012
>
> #include <abstractions/base>
> #include <abstractions/consoles>
> @@ -108,3 +108,22 @@
> /bin/dash rmix,
> /bin/dd rmix,
> /bin/cat rmix,
> +
> + /usr/libexec/qemu-bridge-helper Cx,
> + # child profile for bridge helper process
> + profile /usr/libexec/qemu-bridge-helper {
> + #include <abstractions/base>
> +
> + capability setuid,
> + capability setgid,
> + capability setpcap,
> + capability net_admin,
> +
> + network inet stream,
> +
> + /dev/net/tun rw,
> + /etc/qemu/** r,
> + owner @{PROC}/*/status r,
> +
> + /usr/libexec/qemu-bridge-helper rmix,
> + }
Looking at the child profile itself, this seems fine.
However, the Cx transition makes it so that all libvirt-managed qemu
processes are allowed to execute this setuid helper and I wonder if that
is too much? Ie, a guest running under libvirt's NAT wouldn't need
access to this helper at all. I wonder if it would be better to adjust
virt-aa-helper to add this transition and child profile instead (the
child profile could theoretically still be in apparmor/libvirt-qemu, but
this is a bit messy)? Can we determine from the domain XML the
circumstances when /usr/libexec/qemu-bridge-helper will be used? If so,
virt-aa-helper could add the access only then. As a side-benefit,
handling this in virt-aa-helper allows us at compile-time to adjust the
path to qemu-bridge-helper to use the configured path to the binary (ie,
some distros may not use /usr/libexec).
--
Jamie Strandboge | http://www.canonical.com
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