Re: [libvirt] [Patch v2 3/3] apparmor: QEMU bridge helper policy updates

Quoting Jamie Strandboge <jamie(a)canonical.com&gt;: > On Fri, 2012-06-29 at 14:08 -0400, rmarwah(a)linux.vnet.ibm.com wrote: >> From: Richa Marwaha <rmarwah(a)linux.vnet.ibm.com&gt; >> >> 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(a)linux.vnet.ibm.com&gt; >> Signed-off-by: Corey Bryant&lt;coreyb(a)linux.vnet.ibm.com&gt; >> --- >> 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). Thanks a lot reviewing the apparmor patch. We cannot detemine from the domain XML whether /usr/libexec/qemu-bridge-helper will be used or not because we cannot determine whether we are running as privileged user or not.

Is there a way we can specify the configured path to the binary in the current policy we have?