[libvirt] [PATCH V3] apparmor: support ptrace checks

[Guido Günther]

Hi Jim,
On Fri, Sep 22, 2017 at 05:02:42PM -0600, Jim Fehlig wrote:
> Kernel 4.13 introduced finer-grained ptrace checks
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=v4.13.2&id=290f458a4f16f9cf6cb6562b249e69fe1c3c3a07
> 
> With kernel 4.13 and apparmor 2.11, simply starting libvirtd
> results in the following apparmor denial
> 
> type=AVC msg=audit(1506112085.645:954): apparmor="DENIED"
> operation="ptrace" profile="/usr/sbin/libvirtd" pid=6984
> comm="libvirtd" requested_mask="trace" denied_mask="trace"
> peer="unconfined"
> 
> Attempting to start an unconfined domain results in
> 
> type=AVC msg=audit(1506112301.227:1112): apparmor="DENIED"
> operation="ptrace" profile="/usr/sbin/libvirtd" pid=7498
> comm="libvirtd" requested_mask="trace" denied_mask="trace"
> peer="/usr/sbin/libvirtd"
> 
> And attempting to start a confined domain results in
> 
> type=AVC msg=audit(1506112631.408:1312): apparmor="DENIED"
> operation="open" profile="virt-aa-helper" name="/etc/libnl/classid"
> pid=8283 comm="virt-aa-helper" requested_mask="r" denied_mask="r"
> fsuid=0 ouid=0
> type=AVC msg=audit(1506112631.530:1319): apparmor="DENIED"
> operation="open" profile="virt-aa-helper" name="/etc/libnl/classid"
> pid=8289 comm="virt-aa-helper" requested_mask="r" denied_mask="r"
> fsuid=0 ouid=0
> type=AVC msg=audit(1506112632.186:1324): apparmor="DENIED"
> operation="ptrace" profile="/usr/sbin/libvirtd" pid=8342
> comm="libvirtd" requested_mask="trace" denied_mask="trace"
> peer="libvirt-66154842-e926-4f92-92f0-1c1bf61dd1ff"
> 
> Add ptrace rules to allow the trace operations.
> 
> Resolves: https://bugzilla.suse.com/show_bug.cgi?id=1058847
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
> ---
> 
> V3:
>  fix ptrace rule for per-domain profiles
> 
> V2:
>  restrict ptrace permissions
>  drop support for dbus, signal, and unix
>  
>  examples/apparmor/usr.sbin.libvirtd | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/examples/apparmor/usr.sbin.libvirtd b/examples/apparmor/usr.sbin.libvirtd
> index acb59e071..fa4ebb355 100644
> --- a/examples/apparmor/usr.sbin.libvirtd
> +++ b/examples/apparmor/usr.sbin.libvirtd
> @@ -37,6 +37,10 @@
>    network packet dgram,
>    network packet raw,
>  
> +  ptrace (trace) peer=unconfined,
> +  ptrace (trace) peer=/usr/sbin/libvirtd,
> +  ptrace (trace) peer=libvirt-*,
> +

This works here too! And I can even drop the first rule (ptrace (trace)
peer=unconfined) and things still work (and from reading the profile and
Jamies explanations it should work without it). Can you check if that
works for you too?  Otherwise:

Reviewed-By: Guido Günther <agx at sigxcpu.org>


>    # Very lenient profile for libvirtd since we want to first focus on confining
>    # the guests. Guests will have a very restricted profile.
>    / r,
> -- 
> 2.14.1
>