Newer kernels have added a new restriction: if /proc or /sys on the
host has files or non-empty directories which are over-mounted, and
there is no /proc which fully visible, then it assumes there is a
"security" reason for this. It prevents anyone in a non-initial user
namespace from creating a new proc or sysfs mount.
To work around this, this patch adds a new 'nesting.conf' which can be
lxc.include'd from a container configuration file. It adds a
non-overmounted mount of /proc and /sys under /dev/.lxc, so that the
kernel can see that we're not trying to *hide* things like /proc/uptime.
and /sys/devices/virtual/net. If the host adds this to the config file
for container w1, then container w1 will support unprivileged child
containers.
The nesting.conf file also sets the apparmor profile to the with-nesting
variant, since that is required anyway. This actually means that
supporting nesting isn't really more work than it used to be, just
different. Instead of adding
lxc.aa_profile = lxc-container-default-with-nesting
you now just need to
lxc.include = /usr/share/lxc/config/nesting.conf
(Look, fewer characters :)
Finally, in order to maintain the current apparmor protections on
proc and sys, we make /dev/.lxc/{proc,sys} non-read/writeable.
We don't need to be able to use them, we're just showing the
kernel what's what.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
# Uncomment the line below if you are not using cgmanager
# mount fstype=cgroup -> /sys/fs/cgroup/**,
+ deny /dev/.lxc/proc/** rw,
+ deny /dev/.lxc/sys/** rw,
mount fstype=proc -> /var/cache/lxc/**,
mount fstype=sysfs -> /var/cache/lxc/**,
mount options=(rw,bind),
gentoo.common.conf \
gentoo.moresecure.conf \
gentoo.userns.conf \
+ nesting.conf \
opensuse.common.conf \
opensuse.userns.conf \
oracle.common.conf \
--- /dev/null
+# Use a profile which allows nesting
+lxc.aa_profile = lxc-container-default-with-nesting
+
+# Add uncovered mounts of proc and sys, else unprivileged users
+# cannot remount those
+
+lxc.mount.entry = proc dev/.lxc/proc proc create=dir,optional 0 0
+lxc.mount.entry = sys dev/.lxc/sys sysfs create=dir,optional 0 0
config/templates/gentoo.common.conf
config/templates/gentoo.moresecure.conf
config/templates/gentoo.userns.conf
+ config/templates/nesting.conf
config/templates/opensuse.common.conf
config/templates/opensuse.userns.conf
config/templates/oracle.common.conf