On 09/20/2017 12:51 AM, Guido Günther wrote:
Hi Jim,
On Mon, Sep 18, 2017 at 02:06:13PM -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
When Apparmor is enabled and libvirtd is confined, attempting to start
a domain fails
virsh start test
error: Failed to start domain test
error: internal error: child reported: Kernel does not provide mount
namespace: Permission denied
The audit log contains
type=AVC msg=audit(1505466699.828:534): apparmor="DENIED"
operation="ptrace" profile="/usr/sbin/libvirtd" pid=6621
comm="libvirtd" requested_mask="trace" denied_mask="trace"
peer="/usr/sbin/libvirtd"
It seems access to /proc/<pid>/tasks already requires trace permissions.
It was also noticed that simply connecting to libvirtd (e.g. virsh list)
resulted in the following entries in the audit log
type=AVC msg=audit(1505755799.975:65): apparmor="DENIED"
operation="ptrace" profile="/usr/sbin/libvirtd" pid=1418
comm="libvirtd" requested_mask="trace" denied_mask="trace"
peer="unconfined"
type=AVC msg=audit(1505755799.976:66): apparmor="DENIED"
operation="ptrace" profile="/usr/sbin/libvirtd" pid=1418
comm="libvirtd" requested_mask="trace" denied_mask="trace"
peer="unconfined"
Both Apparmor denials can be fixed by adding ptrace rules to the
libvirtd profile. The new rules only grant trace permission.
I'm seeing the same denials with 4.13 (4.13.1-1~exp1 (2017-09-11) in
Debian) but the proposed profile change does not fix the vm start issue
for me. I can't tell why atm, will have to look into this in more detail
at the WE.
I have other problems when running with 'security_default_confined = 1' in
qemu.conf, but the changes allow starting unconfined domains.
Cedric remembered this old thread
https://www.redhat.com/archives/libvir-list/2014-October/msg00011.html
Some of those changes have been merged, but the ptrace, dbus, signal, etc. have
not. I used Stefan's changes to the libvirtd profile but still see the same
issue with confined domains
type=AVC msg=audit(1505858407.661:123): apparmor="DENIED"
operation="change_profile" info="label not found" error=-2
profile="/usr/sbin/libvirtd" name="libvirt-66154842-e926-4f92-92f0-1c1bf61dd1ff"
pid=3149 comm="libvirtd"
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